Position indicator

A position indicator includes: a core body disposed within a casing such that a tip thereof projects from one opening of the casing; a printed board on which a circuit element for detecting pressing force applied to the tip is disposed; and a pen pressure detecting module formed by arranging, in an axial direction, plural parts for detecting a displacement corresponding to the pressing force. The plural parts are arranged within a hollow portion of a cylindrical holder portion housed within the casing. The holder portion has an opening portion in a side circumferential surface thereof. The opening portion is opened in a direction perpendicular to the axial direction. At least one of the parts is/are housed into the hollow portion through the opening portion. The holder portion includes a locking portion configured to prevent the at least one of the parts from falling out through the opening portion.

BACKGROUND

1. Field of the Invention

The present invention relates to a position indicator in the shape of a pen, for example, which is used in conjunction with a position detecting device, and particularly to a position indicator having a function of detecting pressure (pen pressure) applied to a tip portion (pen point) of a core body.

2. Description of the Related Art

A position input device has recently been used as an input device for a tablet type PC (personal computer) or the like. The position input device includes, for example, a position indicator formed in the form of a pen, and a position detecting device having an input surface, on which pointing operation and input of characters, figures, and the like are performed based on the use of the position indicator.

Conventionally, as a pen type position indicator of this kind, a position indicator for a position detecting device of an electromagnetic induction system is well known. The position indicator of the electromagnetic induction system has a resonance circuit formed by connecting a resonance capacitor to a coil wound around a ferrite core. The position indicator indicates a position on the position detecting device by transmitting a resonance signal generated by the resonance circuit to the position detecting device.

The pen type position indicator of this kind is also configured conventionally to have a function of detecting pressure (pen pressure) applied to a tip portion (pen point) of a core body and transmitting the pressure (pen pressure) to the position detecting device. To detect the pen pressure, known methods use a mechanism that changes the inductance of the coil forming the resonance circuit according to the pen pressure or a mechanism that changes the capacitance of the capacitor forming the resonance circuit according to the pen pressure. When either of the methods is used, a pen pressure detecting section is formed into a pen pressure detecting module as one functional unit.

FIGS. 19A and 19Bshow a conventional example of construction of a variable capacitance capacitor type pen pressure detecting module that changes the capacitance of a capacitor forming a resonance circuit of a position indicator according to pen pressure. The conventional example is described in Patent Document 1 (Japanese Patent Laid-Open No. 2011-186803).

FIG. 19Ais a general perspective view of the variable capacitance capacitor forming the pen pressure detecting module.FIG. 19Bis a sectional view taken along line Z-Z ofFIG. 19A, and is a longitudinal sectional view of the variable capacitance capacitor.

The variable capacitance capacitor100in the example ofFIGS. 19A and 19Bchanges in capacitance according to pressure (pen pressure) applied to a core body101(see alternate long and short dashed lines inFIG. 19B) of the position indicator. The position indicator detects the pen pressure applied to the core body101on the basis of the change in the capacitance of the variable capacitance capacitor, and transmits the detected pen pressure to a position detecting device.

As shown inFIG. 19AandFIG. 19B, the variable capacitance capacitor100includes a dielectric103, a terminal member104, a retaining member105, a conductive member106, and an elastic member107within a cylindrical holder102made of a resin, for example.

The dielectric103for example has substantially a disk shape. The dielectric103has a substantially circular first surface portion103aand a substantially circular second surface portion103bopposed to the first surface portion103aso as to be substantially parallel to the first surface portion103a. In the present example, the first surface portion103aand the second surface portion103bare both formed in a planar shape.

As shown inFIG. 19B, the dielectric103is mounted on a flange portion102aof the holder102with the second surface portion103bfaced toward another end side in an axial direction of the holder102on which end side the core body101is present.

The terminal member104is formed of a conductive metal. The terminal member104has a flat portion104aas an example of a surface portion engaged with the first surface portion103aof the dielectric103, two locking portions104band104cformed so as to be continuous from the flat portion104a, and a lead piece104dsimilarly formed so as to be continuous from the flat portion104a.

The two locking portions104band104chave substantially the shape of a letter J, and are provided so as to sandwich the flat portion104atherebetween. The two locking portions104band104cprovide elasticity to the terminal member104so that the flat portion104aof the terminal member104is always biased elastically in directions toward end portions of the locking portions104band104c. The end portions of the locking portions104band104care provided with opening portions104eand104fhaving substantially a quadrangular shape, for example.

As shown inFIG. 19AandFIG. 19B, the terminal member104is fixed to the holder102, with the opening portions104eand104fof the two locking portions104band104clocked to locking tooth portions102band102cof the holder102.

At this time, because the terminal member104has the elasticity provided by the two locking portions104band104c, the flat portion104aabuts against the first surface portion103aof the dielectric103in a state of being pressed against the first surface portion103a. The flat portion104aof the terminal member104has a surface shape (flat surface in the present example) corresponding to the surface shape of the first surface portion103aof the dielectric103. Thus, the flat portion104aand the first surface portion103aof the dielectric103abut against each other without any gap therebetween, and are securely connected electrically to each other.

The lead piece104dof the terminal member104is connected to a contact portion of a printed board (not shown), disposed on an opposite side from the core body101, by resistance welding or ultrasonic welding, for example. The terminal member104is thereby connected electrically to electronic parts on the printed board. The lead piece104dof the terminal member104forms a first electrode of the variable capacitance capacitor100.

The retaining member105has a base portion105ahaving an outside diameter slightly smaller than the inside diameter of a hollow portion of the holder102and a substantially cylindrical fitting portion105b. An engaging recessed portion105c(seeFIG. 19B) recessed in substantially a cylindrical shape is provided in the base portion105a. An end portion in the axial direction of the core body101is press-fitted into the engaging recessed portion105c, whereby the core body101is coupled to the retaining member105.

In addition, the fitting portion105bas a recessed portion for attaching the conductive member106is formed in the retaining member105so as to project to an opposite side from the core body101side of the base portion105a. The conductive member106is fitted into the fitting portion105b.

As shown inFIG. 19B, the conductive member106is formed in the form of a shell, for example, and has a curved surface portion106aat one end in the axial direction of the conductive member106. A cylindrical portion106bon another end side in the axial direction of the conductive member106is fitted into the fitting portion105bof the retaining member105. The diameter of the cylindrical portion106bof the conductive member106is, for example, set somewhat larger than the inside diameter of the fitting portion105bof the retaining member105. The relation of a fit between the conductive member106and the fitting portion105bof the retaining member105is thereby set as the relation of a frictional fit. As a result, the conductive member106is prevented from falling off the fitting portion105bof the retaining member105.

The conductive member106has conductivity, and is formed of an elastic member capable of elastic deformation. Such an elastic member includes for example a silicon conductive rubber, a pressure conductive rubber (PCR: Pressure sensitive Conductive Rubber), and the like. When such an elastic member is used as the conductive member106, a contact area between the second surface portion103bof the dielectric103and the curved surface portion106aof the conductive member106is increased with an increase in pen pressure (pressure) applied to the core body101.

The elastic member107is for example a coil spring having conductivity. The elastic member107has a winding portion107ahaving elasticity, a terminal piece107bat one end portion of the winding portion107a, and a connecting portion107cat another end portion of the winding portion107a.

As shown inFIG. 19B, the winding portion107aof the elastic member107is disposed so as to cover the periphery of the conductive member106with the fitting portion105bof the retaining member105interposed therebetween. At this time, the connecting portion107cof the elastic member107is interposed between the retaining member105and the conductive member106, and comes into contact with the conductive member106. The elastic member107is thereby electrically connected to the conductive member106.

In addition, as shown inFIG. 19A, when the elastic member107is housed in the holder102, the terminal piece107bof the elastic member107projects to one end side in the axial direction of the holder102through a through hole (not shown) provided in the holder102. The terminal piece107bis connected to a contact portion (not shown) of the printed board by soldering, resistance welding, or ultrasonic welding, for example. The terminal piece107bof the elastic member107forms a second electrode of the variable capacitance capacitor100.

Two engaging projecting portions105dand105ehaving a substantially triangular sectional shape are provided on two flat surface portions opposed to each other in side surface portions of the base portion105aof the retaining member105. Engaging holes102dand102ewith which the engaging projecting portions105dand105eof the retaining member105are engaged are formed in the holder102.

In a state in which the conductive member106is fitted in the fitting portion105b, and the elastic member107is disposed around the periphery of the conductive member106and electrically coupled to the conductive member106, the retaining member105is press-fitted into the holder102so that the two engaging projecting portions105dand105eare engaged with the two engaging holes102dand102eprovided in the holder102. Then, the elastic member107is retained between the flange portion102aof the holder102and the base portion105a, and the retaining member105is retained in the holder102in a state of being movable along the axial direction of the holder102by the length of the engaging holes102dand102ein the axial direction of the holder102.

At this time, as shown inFIG. 19B, the curved surface portion106aformed on one end side in the axial direction of the conductive member106is disposed so as to be opposed to the second surface portion103bof the dielectric103, and the conductive member106forms the second electrode portion of the variable capacitance capacitor100.

In the variable capacitance capacitor100formed as described above, as shown inFIG. 19B, in a state in which no pressure (pen pressure) is applied to the core body101(initial state), the conductive member106is physically separated from the second surface portion103bof the dielectric103, and is not in contact with the second surface portion103b. When pressure is applied to the core body101, the thickness of an air layer between the conductive member106and the second surface portion103bof the dielectric103becomes smaller than in the initial state.

As the pressure applied to the core body101increases, the curved surface portion106aof the conductive member106comes into contact with the second surface portion103bof the dielectric103. The contact area between the second surface portion103bof the dielectric103and the curved surface portion106aof the conductive member106corresponds to the pressure applied to the core body101.

The state between the first electrode and the second electrode of the variable capacitance capacitor100changes as described above according to the pressing force applied to the core body101. Thus, the capacitance of a capacitor formed between the first electrode and the second electrode changes according to the pressing force applied to the core body101.

The above-described example is an example of a variable capacitance capacitor type pen pressure detecting module. Also in a case of an inductance detection type pen pressure detecting module, a plurality of parts are arranged in the axial direction of a core body of a position indicator (see Patent Document 2 (Japanese Patent Laid-Open No. 2002-244806), for example). In this case, the casing of the position indicator plays a role of a holder for housing the plurality of parts of the pen pressure detecting module.

BRIEF SUMMARY

As described above, the pen pressure detecting module has the plurality of parts arranged within the hollow holder in the axial direction of the core body of the position indicator. The portion of the pen pressure detecting module is conventionally manufactured by inserting and arranging all of the plurality of parts of the pen pressure detecting module into the hollow portion of the cylindrical holder from one opening and another opening in the axial direction of the holder.

It is thus necessary to insert and arrange all of the plurality of parts forming the pen pressure detecting module into the hollow portion of the holder while considering alignment of all of the plurality of parts forming the pen pressure detecting module in the axial direction and in a direction orthogonal to the axial direction. However, it is difficult to surely achieve the alignment in the axial direction and in the direction orthogonal to the axial direction. Therefore, in a process of manufacturing the portion of the pen pressure detecting module, the difficulty is involved in work, and the number of man-hours is increased, so that the pen pressure detecting module is not suitable for mass production.

In addition, when the pen pressure detecting module is formed as one module part by housing the plurality of parts in the holder separate from the casing of the position indicator as in the above-described example, the manufacturing of the module part takes much time, so that the module part is not suitable for mass production, as described above, and cost is increased.

According to one aspect of the present invention, a position indicator is provided that can solve the above problems.

According to a first aspect of the present invention, there is provided a position indicator including: a cylindrical casing; a core body disposed within the casing such that a tip of the core body projects from one opening end side of the casing; a printed board disposed within the casing, a circuit element being disposed on the printed board for detecting pressing force applied to the tip of the core body; and a pen pressure detecting module formed by arranging a plurality of parts for detecting a displacement of the core body in an axial direction of the casing, the displacement corresponding to the pressing force applied to the tip, in the axial direction within a hollow portion of a cylindrical holder portion housed within a hollow portion of the casing such that an axial direction of the cylindrical holder portion coincides with the axial direction of the casing; wherein the holder portion has an opening portion in a portion of a side circumferential surface of the holder portion, the opening portion being opened in a direction perpendicular to the axial direction of the holder portion, at least one of the plurality of parts is (are) housed into the hollow portion of the cylindrical holder portion in the direction perpendicular to the axial direction through the opening portion, and the holder portion includes a locking portion for preventing the at least one of the plurality of housed parts from falling out through the opening portion.

In the position indicator according to the first aspect of the present invention having the above-described construction, the at least one of the plurality of parts forming the pen pressure detecting module is (are) housed through the opening portion formed in a portion of the side circumferential surface of the cylindrical holder portion and opened in the direction perpendicular to the axial direction of the holder portion. In this case, the at least one of the plurality of parts housed in the holder portion may fall out through the opening portion. In the present invention, however, the holder portion has the locking portion for preventing the at least one of the plurality of housed parts from falling out through the opening portion, so that the plurality of housed parts will be retained in the holder portion.

In addition, according to a second aspect of the present invention, the plurality of parts forming the pen pressure detecting module include one or more first parts displaced in the axial direction of the casing according to the pressing force applied to the tip of the core body and a second part for always biasing at least one of the first parts toward a side of the tip of the core body. When the plurality of parts are housed into the cylindrical holder portion in the direction perpendicular to the axial direction through the opening portion, the at least one of the first parts is moved in the axial direction and engaged with the locking portion of the holder portion by a biasing force of the second part within the hollow portion of the holder portion, whereby the locking portion of the holder portion prevents the plurality of parts from falling out through the opening portion.

In the second aspect of the present invention, the plurality of parts forming the pen pressure detecting module include one or more first parts displaced in the axial direction of the casing according to the pressing force applied to the tip of the core body, and the second part for always biasing at least one of the first parts toward the side of the tip of the core body. When the plurality of parts forming the pen pressure detecting module are housed via the opening portion opened in the direction perpendicular to the axial direction of the holder portion, the second part moves the at least one of the first parts in the axial direction by the elastic biasing force of the second part. The locking portion is engaged with the at least one of the first parts moved in the axial direction.

Because the second part applies the elastic biasing force in the axial direction to the plurality of parts as a whole, when the at least one of the first parts is engaged with the locking portion and is prevented from falling out through the opening portion, the plurality of parts as a whole are prevented from falling out through the opening portion.

In addition, according to a third aspect of the present invention, the locking portion of the holder portion includes a pair of edge portions of the opening portion along the axial direction, which are opposed to each other. The pair of edge portions is elastically displaced such that at least one of the plurality of parts increases a distance between the pair of edge portions when the plurality of parts are housed (inserted) into the cylindrical holder portion in the direction perpendicular to the axial direction through the opening portion, and the distance between the pair of edge portions is elastically restored to an original state when the plurality of parts are housed within the cylindrical holder portion, whereby the locking portion of the holder portion prevents the plurality of parts from falling out through the opening portion.

In the third aspect of the present invention, the locking portion of the holder portion includes the pair of edge portions of the opening portion along the axial direction, which are opposed to each other. When the plurality of parts are put (inserted) through the opening portion in the direction perpendicular to the axial direction to be housed into the cylindrical holder, the pair of edge portions is elastically displaced such that at least a part of the plurality of parts increases the distance between the pair of edge portions. When the plurality of parts are housed within the cylindrical holder portion, the pair of edge portions forming the locking portion elastically restores the distance therebetween to an original state. The plurality of parts are thereby prevented from being displaced thorough the opening portion of the holder portion.

According to the present invention, at least one of the plurality of parts for pen pressure detection is/are housed into the hollow portion of the holder portion via the opening portion opened in the direction perpendicular to the axial direction of the holder portion in a portion of the side circumferential surface of the cylindrical holder portion. Thus, as compared with the case where the plurality of parts for pen pressure detection are sequentially housed in the axial direction into the hollow portion of the cylindrical holder portion, a process of manufacturing the pen pressure detecting module can be simplified, and mass productivity is improved.

In addition, even when the plurality of parts are housed into the hollow portion of the holder portion through the opening portion formed in the side circumferential surface of the cylindrical holder portion, the locking portion of the holder portion prevents the plurality of housed parts from falling out through the opening portion.

According to the present invention, the housed state of the plurality of parts within the cylindrical holder portion can be monitored and visually verified through the opening portion. Thus, the positional relation of the plurality of parts forming the pen pressure detecting module within the holder portion can be maintained to be a predetermined positional relation at all times.

DETAILED DESCRIPTION

A few embodiments of a position indicator according to the present invention will hereinafter be described with reference to the drawings.

First Embodiment

FIGS. 1A to 4Care diagrams of assistance in explaining an example of construction of a first embodiment of the position indicator according to the present invention.FIG. 2shows an example of an electronic device200using the position indicator1according to the first embodiment. In the present example, the electronic device200is a high-functionality portable telephone terminal having a display screen200D of a display device, such as an LCD (Liquid Crystal Display), and includes a position detecting device202of an electromagnetic induction system under (on the back side of) the display screen200D.

A casing of the electronic device200in the present example has a housing recessed hole201for housing the position indicator1in the shape of a pen. A user extracts the position indicator1housed in the housing recessed hole201from the electronic device200, and performs position indicating operation on the display screen200D, as required.

When position indicating operation is performed on the display screen200D of the electronic device200by the position indicator1in the shape of a pen, the position detecting device202provided on the back side of the display screen200D detects the position operated (acted on) by the position indicator1and pen pressure, and a microcomputer included in the position detecting device202of the electronic device200performs display processing corresponding to the operated position on the display screen200D and the pen pressure.

FIGS. 1A and 1Bschematically show the position indicator1as a whole according to the first embodiment.FIG. 1Ashows the inside of a case main body2aof a case2(casing) of the position indicator1with only the case main body2acut away for purposes of illustration.FIG. 1Bis a view of the position indicator1according to the first embodiment as viewed in an axial direction from the side of a core body4.

As shown inFIG. 1A, the position indicator1has the case2forming a bottomed cylindrical casing that is long and thin in the axial direction and which is closed on one side. The case2is formed of a resin, for example, and includes the case main body2aof a cylindrical shape having a hollow portion therewithin and a case cap2bcoupled to the case main body2a. The core body4and a magnetic core wound with a coil5, or a ferrite core6in the present example, are coupled to and housed in a board holder3within the hollow portion of the case main body2a. The ferrite core6in the present example has a cylindrical shape.

The board holder3is formed of a resin, for example, and is formed so as to have a pressure sensing part holder portion3aand a printed board mounting base portion3bcontinuous with each other in a longitudinal direction as the axial direction of the position indicator1when the board holder3is housed within the hollow portion of the case main body2a. Pressure sensing parts (a plurality of parts for pen pressure detection)7are housed in the pressure sensing part holder portion3a. A printed board8is mounted and retained on the printed board mounting base portion3b. The pressure sensing part holder portion3awill hereinafter be abbreviated to the holder portion3afor the simplicity of description. The holder portion3ais formed closest to the core body4in the board holder3. The core body4and the ferrite core6are coupled to the holder portion3a.

FIG. 3Ais a sectional view taken along line X-X ofFIG. 1B, and is a partial sectional view of the position indicator1sectioned in a direction passing through the axial position of the position indicator1and parallel with a board surface (surface on which a conductor pattern is printed and formed and circuit parts are mounted)8aof the printed board8.FIG. 3Bis a sectional view taken along line Y-Y ofFIG. 1B, and is a partial sectional view of the position indicator1sectioned in a direction passing through the axial position of the position indicator1and perpendicular to the board surface8aof the printed board8.FIG. 3Cis a perspective view directing attention to the holder portion3a, in particular, of the board holder3.

FIG. 4Bis a diagram showing a state in which the core body4and the ferrite core6are coupled to the board holder3.FIG. 4Ais an exploded perspective view of assistance in explaining the holder portion3aof the board holder3and the pressure sensing parts7.FIG. 4Cis a sectional view taken along line A-A ofFIG. 4A, and is a longitudinal sectional view of the holder portion3aof the board holder3.

As shown inFIG. 4B, the printed board8is mounted on the printed board mounting base portion3bof the board holder3. The printed board8is of a long and thin rectangular shape having a width smaller than the inside diameter of the case main body2aand having a predetermined length in the longitudinal direction. The length in the longitudinal direction of a board mounting flat surface of the printed board mounting base portion3bis substantially equal to or slightly larger than the length in the longitudinal direction of the printed board8. In addition, the length in a width direction of the board mounting flat surface of the printed board mounting base portion3bis selected to be slightly larger than the width of the printed board8.

Though not shown, one end and the other end of the coil5extend to the printed board8using a clearance between the board holder3and the case main body2a, and are for example soldered to a conductive pattern formed on the printed board8. In the example ofFIG. 4B, a notch portion31is formed in a portion in the longitudinal direction of the board holder3, and the one end and the other end of the coil5are soldered on a back surface side opposite from the board surface8aof the printed board8and are connected to the conductive pattern on the printed board8via a through hole.

The printed board8is provided with a push switch (side switch)11that is turned on when depressed and which returns to an off state when the depression is stopped, and is provided with capacitors12and13forming a resonance circuit together with the coil5. The capacitor12in the present example is a trimmer capacitor whose capacitance can be adjusted. Further, in the first embodiment, an IC14is provided on the printed board8, and other circuit parts and a conductor pattern not shown in the figures are formed on the printed board8.

In the present example, a through hole15(seeFIG. 2) is made at a position of a side circumferential surface of the case main body2aof the position indicator1which position corresponds to the side switch11. A depression operating element16of the side switch11is exposed such that the side switch11can be depressed through the through hole15. In this case, a predetermined function is assigned and set to the operation of depressing the side switch11by the depression operating element16on the side of the electronic device200including the position detecting device202. For example, the electronic device200in the present example can assign and set the operation of depressing the side switch11by the depression operating element16as an operation similar to a click operation on a pointing device such as a mouse or the like.

The capacitors12and13forming a portion of the resonance circuit and the IC14in the present example are disposed as chip parts on the printed board8. In the present embodiment, the resonance frequency of the resonance circuit is adjusted by adjusting the capacitance of the trimmer capacitor12.

In the present example, locking portions32and33for locking the printed board8to the printed board mounting base portion3bby sandwiching the printed board8in a direction of thickness thereof at both end portions in the longitudinal direction of the printed board8are formed at both end portions in the longitudinal direction of the printed board mounting base portion3bof the board holder3. As shown inFIG. 1A, the printed board8in a state of being mounted on the printed board mounting base portion3band locked by the locking portions32and33is not in contact with an inner wall surface of the case main body2abut is separated from the case main body2a.

Incidentally, most of the portions of the holder portion3aof the board holder3excluding an opening portion35to be described later, the back side portion of the printed board mounting base portion3b, and a coupling portion3cfor coupling the board holder3and the case cap2bto each other are in contact with the inner wall of the case main body2a, so that the board holder3does not rattle in a direction orthogonal to the axial direction within the hollow portion of the case main body2a.

The pressure sensing parts7formed by a plurality of parts as shown inFIG. 1A,FIGS. 3A to 3C, andFIG. 4Aare housed in the holder portion3aof the board holder3. A pen pressure detecting module is formed by thus housing the pressure sensing parts7in the holder portion3a. A core body main body42of the core body4is coupled to the pen pressure detecting module, whereby the pressure sensing parts7of the pen pressure detecting module detect pen pressure applied to a projecting member41of the core body4. Construction of the pressure sensing parts7of the pen pressure detecting module and the housing of the pressure sensing parts7in the holder portion3awill be described later in detail.

Incidentally, the board holder3has a flat surface3pn(seeFIG. 4A) formed along the axial direction on a side of a side circumferential surface of a cylindrical body34forming the holder portion3a, which side is opposed to the opening portion35with the axial position interposed therebetween and is opposite from the printed board mounting flat surface of the printed board mounting base portion3b. In this case, though not shown in detail, the flat surface3pnis a flush flat surface along the axial direction on the holder portion3aor from the holder portion3ato the printed board mounting base portion3b.

The board holder3is mounted on a predetermined flat surface of a workbench in a stable state without rolling because of the flat surface3pn. In a state of the board holder3being mounted on the flat surface of the workbench, the opening portion35of the holder portion3ais an opening in a direction orthogonal to the predetermined flat surface of the workbench, and the printed board mounting flat surface of the printed board mounting base portion3bis a surface parallel to the predetermined flat surface of the workbench. Therefore, the work of housing the pressure sensing parts7in the holder portion3aof the board holder3mounted on the flat surface of the workbench through the opening portion35can be surely performed, and the printed board8can be surely mounted and locked on the mounting flat surface of the printed board mounting base portion3b.

As shown inFIG. 4B, in the present example, the board holder3is coupled to the case cap2bat the coupling portion3cat an end portion of the printed board mounting base portion3b, which end portion is on the opposite side from the holder portion3ain the longitudinal direction, so that the case cap2band the board holder3can be handled as an integral object.

Hence, in the present example, as will be described later, an object formed by mounting and fixing the printed board8on the printed board mounting base portion3bof the board holder3, housing the pressure sensing parts7in the holder portion3a, and coupling the ferrite core6wound with the coil5and the core body4to the board holder3can be handled as one module part. The module part is housed within the hollow portion of the case main body2a, whereby the position indicator1is completed. At this time, the board holder3is coupled to the case cap2bso as to be locked to the inside of the case main body2ain such a state that the position of a center line in the axial direction of the holder portion3acoincides with the position of a center line in the axial direction of the cylindrical case main body2a.

As shown inFIG. 1AandFIG. 3A, one end side in the axial direction of the case main body2ais a pen point side of the position indicator1in the shape of a pen, and a through hole21(opening) is provided on the pen point side of the case main body2a.

The core body4in the present example is formed by the projecting member (pen point member)41projecting from the through hole21of the case main body2ato the outside and the core body main body42. The core body4is made of a synthetic resin such as a polyacetal resin (Duracon) or the like in consideration of resistance to friction when the projecting member41is used in a state of abutting against the operating surface.

The core body main body42is a cylindrical rod-shaped body having a smaller diameter than the diameter of the projecting member41. In the present example, a through hole6ahaving a larger inside diameter than the diameter of the core body main body42is formed in the ferrite core6in the axial direction of the ferrite core6. The core body main body42of the core body4is inserted through the through hole6aof the ferrite core6to be coupled to one of the plurality of parts forming the pressure sensing parts7, as will be described later.

In addition, one end side (side opposite from the side of the projecting member41of the core body4) in the axial direction of the ferrite core6is coupled to the holder portion3aof the board holder3via an anti-falling member9formed of an elastic material, for example a silicon rubber in the present example.

When the integrated module part formed by coupling the core body4and the ferrite core6wound with the coil5to the board holder3as shown inFIG. 4Bis inserted into the hollow portion of the case main body2a, and the case main body2ais coupled to the case cap2b, another end side in the axial direction of the ferrite core6abuts against a stepped portion22formed in the through hole21of the case main body2a, as shown inFIG. 1AandFIG. 3A. The ferrite core6wound with the coil5is thereby fixed between the holder portion3aof the board holder3and the stepped portion22of the case main body2a.

Example of Construction of Pen Pressure Detecting Module

Next, description will be made below of the holder portion3aof the board holder3and the pressure sensing parts7forming the pen pressure detecting module as well as the housing of the pressure sensing parts7in the holder portion3a. The pen pressure detecting module in the present example uses a variable capacitance capacitor whose capacitance varies according to pen pressure applied to the core body as with the pen pressure detecting module described at the beginning with reference to Patent Document 1.

As shown inFIG. 4A, the pressure sensing parts7in the present example are formed by a plurality of parts, that is, a dielectric71, a terminal member72, a retaining member73, a conductive member74, and an elastic member75. The terminal member72forms a first electrode of the variable capacitance capacitor formed by the pressure sensing parts7. In addition, the conductive member74and the elastic member75are electrically connected to each other to form a second electrode of the variable capacitance capacitor.

As shown inFIG. 3CandFIG. 4A, the holder portion3aof the board holder3is formed by the cylindrical body34having a hollow portion, and is formed so as to house the pressure sensing parts7arranged in the axial direction within the hollow portion of the cylindrical body34.

Of the pressure sensing parts7formed by the plurality of parts as described above, the dielectric71and the terminal member72, which are parts not moving in the axial direction within the holder portion3aformed by the cylindrical body34, are inserted in the direction orthogonal to the axial direction of the cylindrical body34and perpendicular to the board surface8aof the printed board8, through the opening portion35formed in a portion of the side circumferential surface of the cylindrical body34forming the holder portion3aand opened in the direction orthogonal to the axial direction, as shown inFIG. 4A, and are housed as shown inFIG. 3CandFIG. 4B.

As shown inFIGS. 4A to 4C, the opening portion35is formed in an end portion of the side circumferential surface of the cylindrical body34forming the holder portion3a, which end portion is on the side of the printed board mounting base portion3b. The opening portion35is opened in the direction orthogonal to the axial direction and opened in the direction perpendicular to the board surface8aof the printed board8mounted on the printed board mounting base portion3b. The opening portion35has a predetermined length d1(seeFIG. 4C) in the axial direction, and has a predetermined length d2(not shown) in the direction orthogonal to the axial direction.

The length d1is selected to be larger than the length (thickness) in the axial direction of the dielectric71and the terminal member72when the dielectric71and the terminal member72are superposed on each other in the axial direction. The length d2is selected to be slightly larger than the larger length of the lengths of the dielectric71and the terminal member72in the direction orthogonal to the axial direction. Thus selecting the dimensions of the lengths d1and d2enables the dielectric71and the terminal member72superposed on each other in the axial direction to be housed within the holder portion3athrough the opening portion35.

In addition, the cylindrical body34forming the holder portion3ahas an inside diameter d3(seeFIG. 4C), and has an opening36aon the side of the core body4in the axial direction of the cylindrical body34. A portion36having the opening36aon the side of the core body4in the axial direction does not have an opening in the side circumferential surface. In the present embodiment, the length d2in the direction orthogonal to the axial direction of the opening portion35in the side circumferential surface of the cylindrical body34is selected to be equal to the inside diameter d3of the cylindrical body34, but is selected to be larger by the depth of a recessed groove39, to be described later, in the portion of the recessed groove39.

The cylindrical body34forming the holder portion3ais closed by a wall portion37on the side of the printed board mounting base portion3b. The locking portion32described above is formed on the wall portion37so as to project on the side of the printed board mounting base portion3b. The opening portion35is formed so as to expose the wall portion37to the outside. That is, the opening portion35is made in the side circumferential surface of the cylindrical body34so as to form an opening of the length d1from the wall portion37in the axial direction.

Slits38aand38bhaving a predetermined width slightly larger than the thickness of the terminal member72in the axial direction are formed in a coupling portion of the side circumferential surface of the cylindrical body34, which coupling portion is coupled to the wall portion37. The recessed groove39(seeFIG. 3AandFIG. 4C) having a larger inside diameter than the inside diameter d2of the portion of the cylindrical body34, in which portion the opening portion35is formed, is formed at a position adjacent to the slits38aand38bin the axial direction in the inner wall of the cylindrical body34.

The dielectric71is formed as a plate-shaped object having an external shape to be fitted into the recessed groove39and having a thickness corresponding to the width in the axial direction of the recessed groove39. Therefore, the dielectric71can be inserted and fitted into the recessed groove39of the cylindrical body34through the opening portion35, and the recessed groove39prevents the dielectric71in the fitted state from moving in the axial direction within the cylindrical body34. Incidentally, in the first embodiment, as will be described later, the dielectric71is pressed and biased by the conductive member74, and is thus pressed to the side of the wall portion37. Therefore the recessed groove39need not be provided.

The terminal member72is formed by a disk-shaped conductive member, for example a plate-shaped object of a conductive metal, which has a thickness slightly smaller than the width in the axial direction of the slits38aand38bof the cylindrical body34and has an outside diameter corresponding to the inside diameter d3of the cylindrical body34. As shown inFIG. 4A, the terminal member72has bulging portions72aand72bto be fitted into the slits38aand38bof the cylindrical body34. Hence, the terminal member72can be inserted so as to be in contact with the wall portion37of the cylindrical body34through the opening portion35, and the bulging portions72aand72bare fitted into the slits38aand38bof the cylindrical body34by the insertion and locked to the cylindrical body34so as not to move in the axial direction.

In addition, a swelling portion72cswelling toward the side of the dielectric71is formed on a central portion of a plate surface of the terminal member72, which plate surface is on the side of the dielectric71. The swelling portion72cplays a role of surely bringing the dielectric71and the terminal member72into contact with each other when the dielectric71and the terminal member72are housed within the cylindrical body34.

The terminal member72plays the role of the first electrode of the variable capacitance capacitor. The terminal member72has a lead portion72dformed from an end surface as an upper end of the terminal member72, which upper end is on the side of the opening portion35. The lead portion72dstraddles the wall portion37of the cylindrical body34to be connected by soldering to a land portion8b(seeFIG. 3C) on the board surface8aof the printed board8mounted on the printed board mounting base portion3bwhen the terminal member72is housed within the holder portion3a.

Further, the terminal member72has an L-shaped projection72eformed in substantially the center of the end surface as the upper end of the terminal member72, which upper end is on the side of the opening portion35. The L-shaped projection72eprojects on an opposite side from the lead portion72dwhen the terminal member72is housed within the holder portion3a. The L-shaped projection72eof the terminal member72holds down the opening side end portion of the dielectric71when the dielectric71and the terminal member72are housed within the holder portion3a. When the lead portion72dof the terminal member72is connected by soldering and thus fixed to the land portion8b(seeFIG. 3C) on the board surface8aof the printed board8, the L-shaped projection72eprevents the dielectric71from falling out through the opening portion35.

The retaining member73has a cylindrical shape portion73ahaving a recessed hole73b, into which to press-fit the core body main body42of the core body4on the core body4side in the axial direction of the retaining member73. The retaining member73also has a ring-shaped projecting portion73chaving a recessed hole73d, into which to fit the conductive member74on an opposite side in the axial direction from the side of the recessed hole73b. In this case, the recessed hole73band the recessed hole73dare formed such that the center line (axial position) of the recessed hole73band the center line (axial position) of the recessed hole73dare located on one straight line.

The outside diameter (portion in a circumferential direction) of the cylindrical shape portion73aof the retaining member73is selected to be slightly smaller than the inside diameter d3of the cylindrical body34. The outside diameter of the ring-shaped projecting portion73cof the retaining member73is selected to be smaller than the outside diameter of the cylindrical shape portion73aand smaller than the inside diameter of a coil spring forming the elastic member75to be described later. In this case, a stepped portion is formed between the ring-shaped projecting portion73cand the cylindrical shape portion73a. The stepped portion is to lock an end portion of the spring as the elastic member75to be described later.

In the present embodiment, slits73eand73fare formed in the cylindrical shape portion73aand the ring-shaped projecting portion73cso as to traverse the recessed hole73band the recessed hole73d, respectively. The presence of the slits73eand73fallows the cylindrical shape portion73aand the ring-shaped projecting portion73cto be elastically displaced (deformed) in the direction orthogonal to the axial direction. Engaging projecting portions73gand73hare formed on the side circumferential surface of the cylindrical shape portion73aof the retaining member73at such positions as to be opposed to each other, while interposing the axial center position of the cylindrical shape portion73atherebetween.

Engaging holes34aand34b(seeFIG. 3BandFIG. 4C), into which to engage the engaging projecting portions73gand73hformed on the side circumferential surface of the cylindrical shape portion73aof the retaining member73, are formed in the side circumferential surface of the cylindrical body34forming the holder portion3a.

The length d4(seeFIG. 4C) in the axial direction of the engaging holes34aand34bis larger than the length in the axial direction of the engaging projecting portions73gand73hformed on the side circumferential surface of the cylindrical shape portion73aof the retaining member73. Thereby, the retaining member73can be moved within the hollow portion of the cylindrical body34in the axial direction of the cylindrical body34even in a state in which the retaining member73is housed within the hollow portion of the cylindrical body34and the engaging projecting portions73gand73hare engaged with the engaging holes34aand34b. Incidentally, as will be described later, the length d4is selected to be a value such that the conductive member74can be moved in the axial direction and abut against the dielectric71and be further elastically deformed in a state in which all of the pressure sensing parts7are housed within the hollow portion of the cylindrical body34.

The conductive member74is made of a conductive and elastically deformable elastic member, and is for example formed by a silicon conductive rubber or a pressure conductive rubber. The conductive member74includes a large-diameter portion74aformed by a cylindrical portion having an outside diameter equal to the outside diameter of the ring-shaped projecting portion73cof the retaining member73and a small-diameter portion74bformed by a cylindrical portion having an outside diameter substantially equal to the diameter of the recessed hole73dof the ring-shaped projecting portion73c. The positions of center lines of the large-diameter portion74aand the small-diameter portion74bare the same. As shown inFIGS. 3A and 3B, an end surface of the large-diameter portion74a, which end surface is on an opposite side from the small-diameter portion74b, is formed so as to have a curved surface portion swelling in the form of a shell. Further, the height of the small-diameter portion74bof the conductive member74is selected to be substantially equal to the depth of the recessed hole73dformed in the ring-shaped projecting portion73cof the retaining member73.

The elastic member75is for example formed by a coil spring having conductivity. The elastic member75has a winding portion75ahaving elasticity, a terminal piece75bat one end portion of the winding portion75a, and a connecting portion75cat another end portion of the winding portion75a. The winding portion75aof the coil spring forming the elastic member75has a diameter that allows the conductive member74to be housed within the winding portion75awithout the winding portion75abeing in contact with the conductive member74, and which diameter is smaller than the diameter of the cylindrical shape portion73aof the retaining member73.

The connecting portion75cof the elastic member75is inserted from the slit portion of the ring-shaped projecting portion73cof the retaining member73into the bottom of the recessed hole73dformed in the ring-shaped projecting portion73c(seeFIG. 3AandFIG. 3B). Hence, when the small-diameter portion74bof the conductive member74is press-fitted into the ring-shaped projecting portion73cof the retaining member73, the end surface of the small-diameter portion74bof the conductive member74is brought into contact with the connecting portion75cof the elastic member75having conductivity, and is thus electrically connected to the connecting portion75c.

The terminal piece75bof the elastic member75straddles the dielectric71, the terminal member72, and the wall portion37, and is connected by soldering to the conductive pattern on the board surface8aof the printed board8mounted on the printed board mounting base portion3b.

Method of Housing Pressure Sensing Parts7in Holder Portion3a

First, the board holder3is mounted on the flat surface of the workbench such that the flat surface3pnfaces the flat surface of the workbench. In this state, the board holder3is positioned such that the opening of the opening portion35faces in an upward direction orthogonal to the flat surface of the workbench and the printed board mounting flat surface of the printed board mounting base portion3bis parallel to the flat surface of the workbench, and the board holder3is locked on the flat surface of the workbench.

Next, the dielectric71and the terminal member72of the pressure sensing parts7are housed within the hollow portion of the cylindrical body34forming the holder portion3athrough the opening portion35. At this time, the dielectric71and the terminal member72are housed within the hollow portion of the cylindrical body34in a state in which the L-shaped projection72eof the terminal member72holds down the opening side end portion of the dielectric71housed within the hollow portion of the cylindrical body34. In addition, at this time, the dielectric71is housed within the recessed groove39formed in the inner wall of the cylindrical body34, and the bulging portions72aand72bof the terminal member72are fitted into the slits38aand38bof the holder portion3a.

Next, in the present example, the small-diameter portion74bof the conductive member74is press-fitted into the recessed hole73dof the ring-shaped projecting portion73cof the retaining member73, and the winding portion75aof the elastic member75is arranged so as to be brought around the periphery of the ring-shaped projecting portion73cand the conductive member74. At this time, the connecting portion75cof the elastic member75is sandwiched between the upper end surface of the small-diameter portion74bof the conductive member74and the bottom of the recessed hole73dof the ring-shaped projecting portion73c, so that the connecting portion75cof the elastic member75and the conductive member74are electrically connected to each other.

Next, the combination of the retaining member73, the conductive member74, and the coil spring of the elastic member75is inserted in the axial direction into the hollow portion of the cylindrical body34from the side of the conductive member74through the opening36aof the cylindrical body34. Then, the combination of the retaining member73, the conductive member74, and the coil spring of the elastic member75is inserted in the axial direction until the engaging projecting portions73gand73hformed on the cylindrical shape portion73aof the retaining member73are fitted into the engaging holes34aand34bformed in the side circumferential surface of the cylindrical body34. At this time, the cylindrical shape portion73aof the retaining member73is elastically deformed in the direction orthogonal to the axial direction and inserted into the hollow portion of the cylindrical body34in spite of the presence of the engaging projecting portions73gand73hbecause the slit73eis formed.

When the engaging projecting portions73gand73hformed on the cylindrical shape portion73aof the retaining member73are fitted into the engaging holes34aand34bformed in the side circumferential surface of the cylindrical body34of the holder portion3a, the retaining member73is locked to the inside of the hollow portion of the cylindrical body34of the holder portion3a. Thus, the retaining member73will not fall out through the opening36aof the cylindrical body34of the holder portion3airrespective of a biasing force in the axial direction of the elastic member75. In addition, in this state, the dielectric71and the terminal member72are pressed to the side of the wall portion37by the biasing force in the axial direction of the elastic member75. This prevents the dielectric71and the terminal member72from falling out through the opening portion35of the cylindrical body34.

That is, locking mechanism for preventing the dielectric71and the terminal member72forming parts of the pressure sensing parts7from being displaced in the direction orthogonal to the axial direction is formed by the engagement between the engaging holes34aand34bformed in the cylindrical body34and the engaging projecting portions73gand73hof the cylindrical shape portion73aof the retaining member73and the biasing force of the elastic member75.

Next, in a state in which all of the plurality of parts forming the pressure sensing parts7are housed and locked within the hollow portion of the cylindrical body34of the holder portion3aas described above, the lead portion72dof the terminal member72is soldered to the land portion8bof the printed board8, and the terminal piece75bof the coil spring as the elastic member75is soldered to the printed board8.

The soldering and fixing of the lead portion72dof the terminal member72and the terminal piece75bof the elastic member75to the printed board8can more surely prevent the terminal member72from falling out through the opening portion35of the holder portion3a. In the present example, the L-shaped projection72eof the terminal member72holds down the opening side end portion of the dielectric71housed within the hollow portion of the cylindrical body34of the holder portion3a. Therefore the soldering and fixing of the terminal member72to the printed board8can more surely prevent the dielectric71from falling out through the opening portion35of the cylindrical body34of the holder portion3a.

The retaining member73fitted with the conductive member74is prevented from moving to the side of the core body4in the axial direction with the engaging projecting portions73gand73hengaged with the engaging holes34aand34bof the cylindrical body34, but is movable to the side of the dielectric71in the axial direction within the hollow portion of the cylindrical body34. When no pen pressure is applied, the biasing force of the elastic member75creates an air space between the conductive member74and the dielectric71.

After the pressure sensing parts7are housed within the cylindrical body34forming the holder portion3aas described above, the anti-falling member9is press-fitted into the opening36aof the cylindrical body34, as shown inFIGS. 3A and 3BandFIG. 4B. AsFIGS. 3A and 3B, the anti-falling member9has a through hole9ainto which to insert the core body main body42of the core body4in the axial direction, and has a cylindrical portion9bhaving an outside diameter substantially equal to or slightly smaller than the inside diameter of the portion36on the side of the opening36aof the cylindrical body34. The anti-falling member9is coupled to the holder portion3aby press-fitting the cylindrical portion9bof the anti-falling member9into the portion36on the side of the opening36aof the cylindrical body34.

In addition, the anti-falling member9has a recessed portion9chaving an inside diameter substantially equal to the outside diameter of the ferrite core6on an opposite side from the cylindrical portion9bin the axial direction. The ferrite core6is coupled to the holder portion3aof the board holder3via the anti-falling member9by press-fitting an end portion of the ferrite core6, which end portion is on an opposite side from the side of the projecting member41of the core body4, into the recessed portion9cof the anti-falling member9.

As described above, the anti-falling member9is formed of a material having elasticity, for example a silicon rubber. Thus, because the ferrite core6is coupled to the holder portion3aof the board holder3via the anti-falling member9, the ferrite core6can be prevented from being damaged even if the position indicator1is dropped and a high acceleration is applied to the coupling portion between the ferrite core6and the holder portion3a.

Next, in a state in which the ferrite core6is coupled to the board holder3as described above, the core body main body42of the core body4is inserted into the through hole6aof the ferrite core6. Then, an end portion of the core body main body42of the core body4is press-fitted into the recessed hole73bof the cylindrical shape portion73aof the retaining member73housed in the holder portion3a. In this case, even in a state in which the core body4is press-fitted in the recessed hole73bof the cylindrical shape portion73a, the core body main body42of the core body4is also exposed from the ferrite core6to the side of the projecting member41of the core body4, as shown inFIG. 3AandFIG. 4B. A pressure (pen pressure) applied to the projecting member41of the core body4can displace the core body4to the side of the case cap2bin the axial direction against the biasing force of the elastic member75.

As described above, the printed board8is mounted on the printed board mounting base portion3bof the board holder3coupled to the case cap2b, the pressure sensing parts7are housed in the holder portion3a, and the ferrite core6and the core body4are coupled to the holder portion3a, whereby a module part as shown inFIG. 4Bis formed.

Next, this module part is inserted into the hollow portion of the case main body2a, so that the projecting member41of the core body4projects from the through hole21of the case main body2ato the outside. Then, the case main body2aand the case cap2bare coupled to each other, whereby the position indicator1is completed.

In the position indicator1, when pressure is applied to the projecting member41of the core body4, the core body4is displaced in a direction of the inside of the case main body2ain the axial direction according to the pressure. Then, the displacement of the core body4displaces the retaining member73within the holder portion3a, which retaining member73is coupled with the core body main body42to the side of the dielectric71against the elastic biasing force of the elastic member75. As a result, the conductive member74fitted in the retaining member73is displaced to the side of the dielectric71, so that a distance between the conductive member74and the dielectric71and, further, a contact area between the conductive member74and the dielectric71change according to the pressure applied to the core body4.

The capacitance of the variable capacitance capacitor formed between the terminal member72forming the first electrode and the conductive member74forming the second electrode thereby changes according to the pressure applied to the core body4. The change in the capacitance of the variable capacitance capacitor is transmitted from the position indicator1to the position detecting device202, whereby the position detecting device202detects the pen pressure applied to the core body4of the position indicator1.

Circuit Configuration for Position Detection and Pen Pressure Detection in First Embodiment

FIG. 5is a diagram showing an equivalent circuit of the position indicator1according to the first embodiment and an example of circuit configuration of the position detecting device202performing position detection and pen pressure detection by electromagnetic induction coupling with the position indicator1.

The position detecting device202in the example ofFIG. 5has a position detecting coil210formed by stacking an X-axis direction loop coil group211and a Y-axis direction loop coil group212, and has a selecting circuit213for sequentially selecting one loop coil of the two loop coil groups211and212.

The position indicator1according to the first embodiment includes a signal control circuit formed by the IC14, and is configured to obtain a driving voltage for driving the IC14from an exciting signal transmitted from an exciting coil214provided to the position detecting device202. Incidentally, description will be made supposing that inFIG. 5, as an example, the loop coil groups211and212of the position detecting device202are used only for the reception of an electromagnetic coupling signal from the position indicator1. However, it is not excluded that the signal control circuit provided to the position indicator1is driven by the electromagnetic coupling between the loop coil groups211and212of the position detecting device202and the position indicator1in place of the exciting coil214. In addition, it is not excluded that a signal such as predetermined control data or the like is transmitted to the signal control circuit provided to the position indicator1.

In the position detecting device202in the example ofFIG. 5, the exciting coil214is disposed so as to surround the position detecting coil210. The exciting coil214inFIG. 5has two turns. In actuality, however, the exciting coil214has a larger number of turns, for example eight to ten turns. As shown in FIG.5, the exciting coil214is connected to a driving circuit222. The driving circuit222is connected to an oscillating circuit221oscillating at a frequency fo.

The driving circuit222is controlled by a processing control section220formed by a microcomputer. The processing control section220controls the driving circuit222to control the supply of an oscillating signal of the frequency fo from the oscillating circuit221to the exciting coil214and thus control signal transmission from the exciting coil214to the position indicator1.

The selecting circuit213selects one loop coil under selection control of the processing control section220. An induced voltage generated in the loop coil selected by the selecting circuit213is amplified in a receiving amplifier223, and supplied to a band-pass filter224, so that only a component of the frequency fo is extracted. The band-pass filter224supplies the extracted component to a detecting circuit225.

The detecting circuit225detects the component of the frequency fo, and supplies a direct-current signal corresponding to the detected component of the frequency fo to a sample and hold circuit226. The sample and hold circuit226holds a voltage value of the output signal of the detecting circuit225in predetermined timing, specifically predetermined timing during a receiving period, and sends out the voltage value to an ND (analog-to-digital) converter circuit227. The ND converter circuit227converts the analog output of the sample and hold circuit226into a digital signal, and outputs the digital signal to the processing control section220. The processing control section220supplies the signal in the predetermined timing to the sample and hold circuit226.

The processing control section220determines whether the digital signal from the ND converter circuit227is a value exceeding a predetermined threshold value, and thereby determines whether the loop coil selected by the selecting circuit213is a loop coil at a position indicated by the position indicator1.

As will be described later, aside from the detection of the position indicated by the position indicator1, the processing control section220also detects the intermittence of a signal from the position indicator1as a digital signal of a few bits, for example 8 bits, and thereby detects pen pressure.

The circuit configuration of the position indicator1is as shown enclosed by a dotted line inFIG. 5. Specifically, the capacitor12is connected in parallel with the coil5as an inductance element. The capacitor13and the side switch11are connected in series with each other. The series circuit of the capacitor13and the side switch11is connected in parallel with the coil5, whereby a resonance circuit301is formed. A switch302is connected in parallel with the resonance circuit301. This switch302is configured to be subjected to on-off control by the IC14.

The IC14is configured to operate on power Vcc obtained by rectifying an alternating-current signal received in the resonance circuit301by electromagnetic induction from the position detecting device202in a rectifying circuit (power supply circuit)305including a diode303and a capacitor304. The IC14is connected to the resonance circuit301via a capacitor306, and monitors conditions of operation of the resonance circuit301. By monitoring the conditions of operation of the resonance circuit301, the IC14can detect conditions of electromagnetic coupling to the exciting coil214of the position detecting device202or, though not described in the present example, a signal such as control data or the like transmitted from the position detecting device202using the two loop coil groups211and212, to perform desired operation control.

The IC14is further connected with the variable capacitance capacitor (capacitance Cv) formed by the pressure sensing parts7. The IC14is configured to be able to detect the capacitance Cv corresponding to pen pressure. The IC14detects the pen pressure in the position indicator1from the value of the capacitance Cv. The IC14then converts the detected pen pressure into a digital signal of 8 bits, for example, and controls the switch302by the digital signal corresponding to the pen pressure. In the above circuit configuration, the variable capacitance capacitor formed by the pressure sensing parts7does not need to form the resonance circuit301. The constituent elements other than the coil5and the variable capacitance capacitor formed by the pressure sensing parts7are all disposed on the printed board8.

Description will be made of position detecting operation and pen pressure detecting operation of the position indicator1and the position detecting device202configured as described above.

The processing control section220first drives the driving circuit222to transmit a signal to the position indicator1from the exciting coil214for a predetermined time. Next, the processing control section220makes the selecting circuit213sequentially select one loop coil of the X-axis direction loop coil group211, and obtains the X-coordinate value of a position indicated by the position indicator1.

The processing control section220next drives the driving circuit222to transmit a signal to the position indicator1from the exciting coil214for a predetermined time. Next, the processing control section220makes the selecting circuit213sequentially select one loop coil of the Y-axis direction loop coil group212, and obtains the Y-coordinate value of the position indicated by the position indicator1.

After detecting the position indicated by the position indicator1as described above, the processing control section220performs transmission that continues for a predetermined time or more from the exciting coil214, and thereafter performs transmission and reception eight consecutive times in similar timing to that of the coordinate detection, to detect 8-bit pen pressure information from the position indicator1. At this time, the selecting circuit213selects a loop coil (which may be either of an X-axis direction loop coil and a Y-axis direction loop coil) closest to the position indicator1according to the detected coordinate value, and receives a signal.

Meanwhile, the IC14of the position indicator1converts pen pressure obtained so as to correspond to the capacitance Cv of the variable capacitance capacitor formed by the pressure sensing parts7into an 8-bit digital signal, and performs on-off control of the switch302by the 8-bit digital signal in synchronism with the transmission and reception of a signal from the position detecting device202. When the switch302is off, the resonance circuit301can return the signal transmitted from the position detecting device202to the position detecting device202. Thus, the loop coil of the position detecting device202receives this signal. On the other hand, when the switch302is on, the resonance circuit301is prohibited from operating. Thus, the signal is not returned from the resonance circuit301to the position detecting device202, and the loop coil of the position detecting device202does not receive the signal.

The processing control section220of the position detecting device202receives the 8-bit digital signal corresponding to the pen pressure by determining whether the signal is received or not eight times, and is thus able to detect the pen pressure information from the position indicator1.

Effects of First Embodiment

Of the pressure sensing parts7, parts not moving in the axial direction even when pen pressure is applied from the core body4, in particular, are desirably arranged in a predetermined state in a predetermined position set in advance in the axial direction within the holder portion3a. According to the first embodiment described above, of the pressure sensing parts7, the dielectric71and the terminal member72, which are parts not moving in the axial direction, are housed into the holder portion3ain a direction orthogonal to the axial direction via the opening portion35having an opening in the direction orthogonal to the axial direction, which opening portion35is provided in the side circumferential surface of the cylindrical body34forming the holder portion3a.

Hence, the dielectric71and the terminal member72as parts not moving in the axial direction (fixed parts) can be surely housed and arranged in a predetermined state in a predetermined position in the axial direction within the hollow portion of the cylindrical body34. In addition, according to the first embodiment, the housed state of these parts can be visually checked easily through the opening portion35.

Since those “fixed parts” are housed and arranged in a predetermined state in a predetermined position within the holder portion3aas described above, in the first embodiment, it suffices to house only the retaining member73, the conductive member74, and the elastic member75, which are other parts (movable parts) moving in the axial direction according to the application of the pen pressure from the core body4among the pressure sensing parts7, into the hollow portion of the cylindrical body34of the holder portion3avia the opening36ain the axial direction of the cylindrical body34.

Therefore, work and the number of man-hours at the time of producing the pen pressure detecting module by housing the pressure sensing parts in the holder while considering alignments of the pressure sensing parts in the axial direction and the direction orthogonal to the axial direction can be simplified and reduced as compared with the conventional pen pressure detecting modules. Thus, the pen pressure detecting module can be manufactured more easily, and work efficiency in the manufacturing of the position indicator is improved, so that the position indicator is suitable for mass production.

According to the first embodiment described above, the dielectric71and the terminal member72in the state of being housed in the hollow portion of the cylindrical body34are pressed to the side of the wall portion37in the axial direction by the biasing force of the elastic member75. The dielectric71and the terminal member72are thereby locked so as not to move in the direction orthogonal to the axial direction. Therefore the dielectric71and the terminal member72are prevented from falling out (springing out) through the opening portion35.

Further, in the first embodiment, the lead portion72dof the terminal member72is soldered and fixed to the printed board8, and the L-shaped projection72eof the terminal member72holds down the opening side end portion of the dielectric71. Thus, the dielectric71and the terminal member72can be more surely prevented from falling out through the opening portion35of the cylindrical body34of the holder portion3a.

In addition, in the first embodiment described above, all of the pressure applied to the core body4is received by the holder portion3aof the board holder3. That is, even when the pressure applied to the core body4brings the conductive member74and the dielectric71in contact with each other, so that pressure is applied to the dielectric71, the pressure applied to the dielectric71in the axial direction is received by the wall portion37of the cylindrical body34forming the holder portion3avia the terminal member72.

Therefore, in the position indicator1according to the first embodiment, the pressure applied to the core body4is not at all applied to the printed board8mounted on the printed board mounting base portion3bof the board holder3. Hence, according to the first embodiment, there is no fear of deformation or the like of the printed board8due to the application of pressure caused by the pen pressure to the printed board8, and there occurs no defect such as a contact failure, variation in circuit characteristics, or the like in the printed board8.

In addition, all of the pressure applied to the core body4is received by the holder portion3aof the board holder3, and the board holder3is partly in contact with the inner wall of the case main body2abut is only housed within the case main body2awithout being fixed to the case main body2aas a whole. Therefore the pressure applied to the core body4is not directly applied to the case main body2a. Hence, even if the position indicator1is placed in harsh conditions such as high-temperature conditions and the like, and even after many years of use of the position indicator1, elastic biasing forces do not continue being applied to the case main body2athrough the board holder3. The case main body2ais thus prevented from being bent.

Further, in the first embodiment described above, the printed board8is mounted and locked on the printed board mounting base portion3bof the board holder3, and the printed board8is smaller than the mounting flat surface of the printed board mounting base portion3b. The printed board8is thus housed without being protruding from the board holder3. Hence, the printed board8is separated from the case main body2a, and is not in contact with the case main body2a.

Therefore, even when an impact is applied to the case main body2ain a case where the position indicator1is dropped, the impact is not directly applied to the printed board8. In addition, even when a force in the axial direction from the side of the case cap or a force in a direction intersecting the axial direction is applied to the case main body2a, the force applied to the case main body2ais not directly applied to the printed board8. That is, the printed board8is in a so-called free state of being free from forces applied to the case main body2a.

Therefore, because excessive forces are not applied to the printed board8, there occurs no defect such as a contact failure, variation in circuit characteristics, or the like in the printed board8. In addition, the parts on the printed board8housed in the board holder3do not need to be readjusted when housed within the case main body2aafter being adjusted before being housed within the case main body2a.

In addition, in the first embodiment described above, the pen pressure detecting module is embodied using the holder portion3aof the board holder3having the printed board mounting base portion3b. Then, the ferrite core6wound with the coil5and the core body4are coupled to the holder portion3aof the board holder3. Thus, all of the parts housed within the case main body2aof the position indicator1can be handled en bloc as a module part.

Therefore, according to the first embodiment, the position indicator1can be manufactured by merely housing the module part within the case main body2a. Thus, as compared with a case where a plurality of parts are arranged in order in the axial direction and housed within the case main body2a, a manufacturing process is simplified, and is suitable for the mass production of the position indicator. In addition, because the printed board8and the pressure sensing parts7are housed in the board holder3, even when a force is applied from the side of the coupling portion3cof the board holder3, the printed board8and the pressure sensing parts7are not affected by the force. Hence, the module part can be handled in a similar manner to a refill for a ballpoint pen or the like. Incidentally, the module part is thinned easily by reducing the size of the pressure sensing parts7.

In addition, in the first embodiment described above, the core body4is replaceable because the core body main body42of the core body4is fitted into the retaining member73of the pressure sensing parts7within the board holder3through the through-hole6aof the ferrite core6.

In addition, the first embodiment provides the following effects as compared with the case where the conventional variable capacitance capacitor described with reference toFIGS. 19A and 19Bis used as pressure sensing parts. In the conventional variable capacitance capacitor100in the example ofFIGS. 19A and 19B, the dielectric103is elastically held down and fixed to the holder102by the terminal member104configured to have elasticity. Thus, a strong impact from the core body101, which impact is caused by the falling of the position indicator1or the like, may break locking tooth portions102band102cof the holder102, causing the terminal member104to come off the holder102, and causing a contact failure of one of the two electrodes sandwiching the dielectric103.

On the other hand, according to the first embodiment described above, the terminal member72can be fitted into the slits38aand38bformed in the cylindrical body34by being inserted into the cylindrical body34forming the holder portion3athrough the opening portion35in the direction orthogonal to the axial direction in a state of being in contact with a surface of the dielectric71. The terminal member72is thereby locked to the holder portion3a. Therefore, even when the position indicator1falls, for example, the terminal member72does not come off the holder portion3a, and no contact failure occurs.

Modification of First Embodiment

In the foregoing first embodiment, the terminal member72housed through the opening portion35has the bulging portions72aand72b, and the cylindrical body34of the holder portion3ahas the slits38aand38b, into which to fit the bulging portions72aand72b. In addition, the recessed groove39into which to fit the dielectric71is formed in the cylindrical body34.

However, the slits38aand38band the recessed groove39of the cylindrical body34can be omitted by forming the construction of the terminal member72and the construction of the cylindrical body34of the holder portion3aas shown inFIG. 6.

FIG. 6is a diagram showing the portions of the pressure sensing parts7and the holder portion3aof the board holder3. In the example ofFIG. 6, the terminal member72in the example ofFIGS. 4A to 4Cis changed to a terminal member72′, and the cylindrical body34forming the holder portion3ain the example ofFIGS. 4A to 4Cis changed to a cylindrical body34′. The construction of other parts is the same as that shown inFIGS. 4A to 4C.

Specifically, in the example ofFIG. 6, the terminal member72′ has a substantially similar construction to that of the terminal member72in the example ofFIGS. 4A to 4C, but does not have the bulging portions72aand72b. An L-shaped projection72fprojecting on an opposite side from the lead portion72dis formed at a position of a lower end portion of the terminal member72′, which lower end portion is on an opposite side from the side of an opening portion35′, the position being such as to be opposed to the L-shaped projection72ewith the swelling portion72cinterposed between the L-shaped projection72fand the L-shaped projection72e. A distance between the L-shaped projection72eand the L-shaped projection72fis in accordance with the size of the dielectric71. The dielectric71can be sandwiched and locked between the L-shaped projection72eand the L-shaped projection72f.

The cylindrical body34′ of the holder portion3adoes not have the slits38aand38bnor have the recessed groove39. In addition, in the cylindrical body34in the example ofFIGS. 4A to 4C, the opening portion35is formed by cutting away the cylindrical body34by the wall thickness of the cylindrical body34, and the wall portion37and the cylindrical body34are lower by the same thickness of the cut-away portion. However, in the example ofFIG. 6, the opening portion35′ corresponding to the opening portion35is formed by making a gap in the side circumferential surface of the cylindrical body34′ in a direction orthogonal to the axial direction, and the height of a wall portion37′ corresponding to the wall portion37is greater than that of the wall portion37.

Therefore, the lead portion72dof the terminal member72cannot straddle the wall portion37′ as it is. In the example ofFIG. 6, however, a recessed groove37a, into which to fit the lead portion72dprecisely, is formed in the wall portion37′ in a vertical direction (direction orthogonal to the axial direction).

In the example ofFIG. 6, the dielectric71sandwiched and positioned between the L-shaped projection72eand the L-shaped projection72fof the terminal member72′ is inserted and housed into the hollow portion of the cylindrical body34′ in the direction orthogonal to the axial direction through the opening portion35′. At this time, the lead portion72dof the terminal member72′ is fitted into the recessed groove37aof the wall portion37′, and an end portion of the lead portion72dis positioned on the side of the printed board8.

The other construction is the same as that of the foregoing first embodiment. In the example ofFIG. 6, the dielectric71can be positioned by being sandwiched between the L-shaped projection72eand the L-shaped projection72fof the terminal member72′ and can be housed into the cylindrical body34′ through the opening portion35′ in the positioned state, which is convenient. In addition, the cylindrical body34′ is simplified in construction because the slits38aand38band the recessed groove39do not need to be formed in the cylindrical body34′.

Second Embodiment

In the foregoing first embodiment, when the plurality of parts forming the pen pressure detecting module are inserted into the cylindrical holder from the axial direction, the retaining member needs to press-fit parts into the holder portion. Therefore, contact portions of the engaging portions formed on the parts and the engaging portions of the holder and the casing may be worn away or chipped. In such a case, the position of the parts after the plurality of parts forming the pen pressure detecting module are incorporated into the holder and the casing of the position indicator may differ for each position indicator. Then, positional relation between the parts of the pen pressure detecting module in each position indicator is not constant, so that the characteristics of pen pressure detection may become different.

In this case, it is desirable if the positional relation between the parts of the pen pressure detecting module within the holder can be checked. Conventionally, however, the check is difficult because the parts are inserted into a cylindrical holder in the axial direction thereof. A second embodiment solves this problem.

FIGS. 7A to 9Dare diagrams of assistance in explaining an example of construction of the second embodiment of the position indicator according to the present invention. As in the first embodiment, a position indicator1A according to the second embodiment is an example of a position indicator used in conjunction with the position detecting device202provided in the electronic device200. Only the construction of parts of a plurality of parts forming pressure sensing parts and the construction of a portion corresponding to the holder portion3aof the board holder3in the position indicator1A according to the second embodiment are different from those of the first embodiment, and the construction of other portions in the position indicator1A according to the second embodiment is similar to that of the first embodiment. Accordingly, the same portions in the position indicator1A according to the second embodiment as in the position indicator1according to the first embodiment are identified by the same reference symbols, and detailed description thereof will be omitted.

FIGS. 7A and 7Bschematically show the position indicator1A as a whole according to the second embodiment. As withFIG. 1A,FIG. 7Ashows the inside of a case main body2aof a case2(casing) of the position indicator1A with only the case main body2acut away for purposes of illustration.FIG. 7Bis a view of the position indicator1A according to the second embodiment as viewed in an axial direction from the side of a core body4.

FIG. 8Ais a sectional view taken along line X′-X′ ofFIG. 7B, and is a partial sectional view of the position indicator1A sectioned in a direction passing through the axial position of the position indicator1A and parallel with a board surface (surface on which a conductor pattern is printed and formed and circuit parts are mounted)8aof a printed board8.FIG. 8Bis a sectional view taken along line Y′-Y′ ofFIG. 7B, and is a partial sectional view of the position indicator1A sectioned in a direction passing through the axial position of the position indicator1A and perpendicular to the board surface8aof the printed board8.FIG. 8Cis a perspective view directing attention to a holder portion3Aa, in particular, of a board holder3A according to the second embodiment.

As in the first embodiment, the board holder3A in the second embodiment has the holder portion3Aa and a printed board mounting base portion3Ab.FIG. 9Bis a diagram showing a state in which the core body4and a ferrite core6are coupled to the board holder3A.FIG. 9Ais an exploded perspective view of assistance in explaining the holder portion3Aa of the board holder3A and pressure sensing parts7A.

Incidentally, only the construction of the holder portion3Aa of the board holder3A is different from that of the holder portion3ain the first embodiment. The printed board mounting base portion3Ab is formed in a similar manner to the printed board mounting base portion3bof the board holder3in the first embodiment, as shown inFIG. 9B.

Also in the present example, the board holder3A has a flat surface3Apn formed along the axial direction on a side of a side circumferential surface of a cylindrical body34A forming the holder portion3Aa, which side is opposed to an opening portion35A to be described later with the axial position interposed therebetween and is opposite from the printed board mounting flat surface of the printed board mounting base portion3Ab. In this case, the flat surface3Apn is a flush flat surface along the axial direction on the holder portion3Aa or from the holder portion3Aa to the printed board mounting base portion3Ab.

Example of Construction of Pen Pressure Detecting Module

Next, description will be made below of the holder portion3Aa of the board holder3A and the pressure sensing parts7A forming the pen pressure detecting module as well as the housing of the pressure sensing parts7A in the holder portion3Aa. The pen pressure detecting module in the present example uses a variable capacitance capacitor whose capacitance varies according to pen pressure applied to the core body as in the first embodiment.

As shown inFIG. 9A, the pressure sensing parts7A in the present example are formed by a plurality of parts, that is, a dielectric71, a terminal member72, a retaining member73A, a conductive member74, and an elastic member75. That is, the pressure sensing parts7A have a similar construction to that of the first embodiment except that the retaining member73A has a different construction from that of the retaining member73in the first embodiment.

As shown inFIG. 8CandFIG. 9A, the holder portion3Aa of the board holder3A is formed by the cylindrical body34A having a hollow portion, and is formed so as to house the pressure sensing parts7A arranged in the axial direction within the hollow portion of the cylindrical body34A.

In the second embodiment, all of the pressure sensing parts7A are inserted in a direction orthogonal to the axial direction of the cylindrical body34A and perpendicular to the board surface8aof the printed board8, through the opening portion35A formed in a portion of the side circumferential surface of the cylindrical body34A forming the holder portion3Aa and opened in the direction orthogonal to the axial direction, as shown inFIG. 9A, and are housed as shown inFIGS. 8A to 8C.

FIG. 9Cis a sectional view taken along line B-B in the cylindrical body34A forming the holder portion3Aa ofFIG. 9A, and is a sectional view obtained by cutting away a portion of the opening portion35A in about the middle in the axial direction of the cylindrical body34A in the direction orthogonal to the axial direction.FIG. 9Dis a sectional view taken along line C-C in the cylindrical body34A forming the holder portion3Aa ofFIG. 9A, and is a sectional view obtained by cutting away the cylindrical body34A in the axial direction thereof.

As shown inFIG. 9A to 9D, the opening portion35A formed in a portion of the side circumferential surface of the cylindrical body34A is opened in the direction orthogonal to the axial direction and opened in the direction perpendicular to the board surface8aof the printed board8mounted on the printed board mounting base portion3Ab. The opening portion35A has a predetermined length d5(seeFIG. 9D) in the axial direction, and has a predetermined length d6(seeFIG. 9C) in a direction orthogonal to the axial direction.

The length d5is selected to be slightly larger than the entire length of the pressure sensing parts7A as a whole arranged in the axial direction, which length is obtained when the pressure sensing parts7A are compressed in the axial direction against the biasing force of the elastic member75. The length d6is selected to be slightly larger than the largest length of the lengths of the plurality of parts forming the pressure sensing parts7A in the direction orthogonal to the axial direction.

In addition, the cylindrical body34A forming the holder portion3Aa has an opening36Aa of an inside diameter d7(seeFIG. 9D) on the side of the core body4in the axial direction of the cylindrical body34A, and has the construction of a ring-shaped locking portion36A having no openings on the side circumferential surface. The inside diameter d7of the ring-shaped locking portion36A is selected to be smaller than the inside diameter d6of the portion in about the middle of the cylindrical body34A, in which portion the opening portion35A is formed (d7<d6). Hence, the hollow portion of the cylindrical body34A has a stepped portion34Ac formed between the ring-shaped locking portion36A and the portion of the inside diameter d6of the cylindrical body34A, in which portion the opening portion35A is formed.

The cylindrical body34A forming the holder portion3Aa is closed by a wall portion37A on the side of the printed board mounting base portion3Ab. A locking portion32is formed on the wall portion37A on the side of the printed board mounting base portion3Ab. Slits38Aa and38Ab having a predetermined width in the axial direction are formed in a coupling portion of the side circumferential surface of the cylindrical body34A, which coupling portion is coupled to the wall portion37A. A recessed groove39A having a larger inside diameter than the inside diameter d6of the portion of the cylindrical body34A, in which portion the opening portion35A is formed, is formed at a position adjacent to the slits38Aa and38Ab in the axial direction in the inner wall of the cylindrical body34A.

In the second embodiment, the dielectric71of the pressure sensing parts7A is formed as a plate-shaped object having an external shape to be fitted into the recessed groove39A and having a thickness corresponding to the width in the axial direction of the recessed groove39A. Therefore, the dielectric71can be inserted and fitted into the recessed groove39A of the cylindrical body34A through the opening portion35A, and the recessed groove39A prevents the dielectric71in the fitted state from moving in the axial direction within the cylindrical body34A.

The terminal member72in the second embodiment is formed by a disk-shaped conductive member, for example a plate-shaped object of a conductive metal, which has the same thickness as the width in the axial direction of the slits38Aa and38Ab of the cylindrical body34A and has an outside diameter corresponding to the inside diameter d6. As shown inFIG. 9A, the terminal member72has bulging portions72Aa and72Ab to be fitted into the slits38Aa and38Ab of the cylindrical body34A. Hence, the terminal member72can be inserted so as to be in contact with the wall portion37A of the cylindrical body34A through the opening portion35A, and the bulging portions72Aa and72Ab are fitted into the slits38Aa and38Ab of the cylindrical body34A by the insertion and locked to the cylindrical body34A. Further, a swelling portion72cswelling on the side of the dielectric71is formed on a central portion of a plate surface of the terminal member72, which plate surface is on the side of the dielectric71. The swelling portion72cplays a role of surely bringing the dielectric71and the terminal member72into contact with each other when the dielectric71and the terminal member72are housed within the cylindrical body34A.

The terminal member72has a lead portion72dstraddling the wall portion37A of the cylindrical body34A to be connected by soldering to a land portion8b(seeFIG. 8C) on the board surface8aof the printed board8mounted on the printed board mounting base portion3Ab.

The retaining member73A has a cylindrical shape including a ring-shaped swelling portion73Ai in a portion in a circumferential direction of a side circumferential surface of the retaining member73A. The retaining member73A has a cylindrical shape portion73Aa having a recessed hole73Ab, into which to press-fit the core body main body42of the core body4on the core body4side in the axial direction of the retaining member73A. The retaining member73A also has a ring-shaped projecting portion73Ac having a recessed hole73Ad, into which to fit the conductive member74on an opposite side in the axial direction from the side of the recessed hole73Ab. In this case, the center line positions of the ring-shaped swelling portion73Ai, the cylindrical shape portion73Aa, and the ring-shaped projecting portion73Ac are the same as the center line position of the retaining member73A of a cylindrical shape, and the recessed hole73Ab and the recessed hole73Ad are formed such that the center line (axial position) of the recessed hole73Ab and the center line (axial position) of the recessed hole73Ad are located on one straight line.

The outside diameter (portion in a circumferential direction) of the ring-shaped swelling portion73Ai of the retaining member73A is selected to be equal to the inside diameter d6of the inside portion of the opening portion35A of the cylindrical body34A. In addition, the outside diameter of the cylindrical shape portion73Aa of the retaining member73A is selected to be slightly smaller than the inside diameter of the ring-shaped locking portion36A of the cylindrical body34A. The diameter of the recessed hole73Ab of the cylindrical shape portion73Aa is selected to be slightly smaller than the diameter of the core body main body42of the core body4. The length (height) in the axial direction of the cylindrical shape portion73Aa is shorter than the length in the axial direction of the ring-shaped locking portion36A of the cylindrical body34A, and is about ½ of the length in the axial direction of the ring-shaped locking portion36A of the cylindrical body34A in the present example.

The outside diameter of the ring-shaped projecting portion73Ac of the retaining member73A is selected to be smaller than the diameter d6of the inside of the opening portion35A of the cylindrical body34A and smaller than the inside diameter of a coil spring forming the elastic member75. In addition, the inside diameter of the ring-shaped projecting portion73Ac is selected to be substantially equal to the outside diameter of a small-diameter portion74bof the conductive member74.

In the present embodiment, slits73Ae and73Af are formed in the cylindrical shape portion73Aa and the ring-shaped projecting portion73Ac so as to traverse the recessed hole73Ab and the recessed hole73Ad, respectively. The presence of the slits73Ae and73Af allows the cylindrical shape portion73Aa and the ring-shaped projecting portion73Ac to be elastically displaced in the direction orthogonal to the axial direction. Hence, the core body main body42and the conductive member74are easily press-fitted into the recessed hole73Ab and the recessed hole73Ad of the cylindrical shape portion73Aa and the ring-shaped projecting portion73Ac, respectively.

The retaining member73A has the construction as described above. Thus, when the retaining member73A is housed in the hollow portion of the cylindrical body34A through the opening portion35A, the cylindrical shape portion73Aa is housed within the ring-shaped locking portion36A of the cylindrical body34A, and an (axial) end surface of the ring-shaped swelling portion73Af abuts against an (axial) end surface of the ring-shaped locking portion36A of the cylindrical body34A, whereby the retaining member73A is prevented from moving to the side of the core body4. That is, the stepped portion34Ac of the cylindrical body34A prevents the retaining member73A from moving in the axial direction to the side of the core body4.

The conductive member74is similar to that of the first embodiment. In the second embodiment, the outside diameter of a large-diameter portion74ais selected to be equal to the outside diameter of the ring-shaped projecting portion73Ac of the retaining member73A, and the outside diameter of the small-diameter portion74bis selected to be substantially equal to the diameter of the recessed hole73Ad of the ring-shaped projecting portion73Ac of the retaining member73A.

A winding portion75aof the coil spring having conductivity, which coil spring forms the elastic member75, has such a diameter as to be able to house the conductive member74and the ring-shaped projecting portion73Ac of the retaining member73A within the winding portion75awithout being in contact with the conductive member74and the ring-shaped projecting portion73Ac of the retaining member73A and as to be smaller than the outside diameter of the cylindrical shape portion73Ac of the retaining member73A.

Also in the second embodiment, a connecting portion75cof the elastic member75is inserted from the notch portion of the ring-shaped projecting portion73Ac of the retaining member73A into the inside of the ring-shaped projecting portion73Ac (seeFIG. 8AandFIG. 8B). Hence, when the small-diameter portion74bof the conductive member74is press-fitted into the recessed hole73Ad of the ring-shaped projecting portion73Ac of the retaining member73A, an upper end surface of the small-diameter portion74bof the conductive member74is brought into contact with and electrically connected to the connecting portion75cof the elastic member75having conductivity.

A terminal piece75bof the elastic member75straddles the dielectric71, the terminal member72, and the wall portion37A, and is connected by soldering to the conductive pattern on the board surface8aof the printed board8mounted on the printed board mounting base portion3Ab.

Method of Housing Pressure Sensing Parts7A in Holder Portion3Aa

First, the board holder3A is mounted on the flat surface of the workbench such that the flat surface3Apn faces the flat surface of the workbench. In this state, the board holder3A is positioned such that the opening of the opening portion35A faces in an upward direction orthogonal to the flat surface of the workbench and the printed board mounting flat surface of the printed board mounting base portion3Ab is parallel to the flat surface of the workbench, and the board holder3A is locked on the flat surface of the workbench.

Next, before the pressure sensing parts7A are housed within the hollow portion of the cylindrical body34A forming the holder portion3Aa through the opening portion35A, the small-diameter portion74bof the conductive member74is first press-fitted into the ring-shaped projecting portion73Ac of the retaining member73A, and the winding portion75aof the elastic member75is arranged so as to be brought around the periphery of the ring-shaped projecting portion73Ac and the conductive member74. At this time, the connecting portion75cof the elastic member75is sandwiched between the upper end surface of the small-diameter portion74bof the conductive member74and the bottom of the retaining member73A, which bottom is surrounded by the ring-shaped projecting portion73Ac, so that the connecting portion75cof the elastic member75and the conductive member74are electrically connected to each other.

Next, the dielectric71is disposed so as to be opposed to a curved surface of the conductive member74, which curved surface is in the form of a shell, and further the terminal member72is disposed so as to be superposed on the dielectric71. Thus, the retaining member73A, the conductive member74and the elastic member75, the dielectric71, and the terminal member72are arranged in this order in the axial direction. Then, the pressure sensing parts7A as a whole are sandwiched between the end surface of the cylindrical shape portion73Ac of the retaining member73A and an end surface of the terminal member72, which end surface is on the opposite side from the dielectric71. At this time, the pressure sensing parts7A as a whole are sandwiched with the elastic member75biased so as to be compressed in the axial direction. A dedicated jig can be used for this sandwiching. Incidentally, the length in the axial direction of the pressure sensing parts7A as a whole, when the pressure sensing parts7A are thus sandwiched by the jig, is slightly shorter than the length d5in the axial direction of the opening portion35A of the cylindrical body34A forming the holder portion3Aa.

Then, the pressure sensing parts7A as a whole that are being sandwiched by the jig are housed into the cylindrical body34A in the direction orthogonal to the axial direction through the opening portion35A of the cylindrical body34A so as to fit the bulging portions72Aa and72Ab of the terminal member72into the slits38Aa and38Ab of the cylindrical body34A and so as to fit the dielectric71into the recessed groove39A. Only the jig is removed. Then, the elastic member75produces a bias by expanding in the axial direction. Because the dielectric71and the terminal member72are fitted so as not to move in the axial direction within the cylindrical body34A, the bias in the axial direction by the elastic member75is applied to only the retaining member73A, in which the conductive member74is press-fitted. As a result, the cylindrical shape portion73Aa of the retaining member73A is inserted and fitted into the ring-shaped locking portion36A of the cylindrical body34A, and the ring-shaped swelling portion73Ai of the retaining member73A is engaged with the stepped portion34Ac of the cylindrical body34A, thus preventing the retaining member73A from moving toward the core body4in the axial direction within the cylindrical body34A.

Then, because the cylindrical shape portion73Aa of the retaining member73A is fitted into the ring-shaped locking portion36A of the cylindrical body34A, the retaining member73A is also prevented from moving in the direction orthogonal to the axial direction. Further, in this state, the elastic member75applies the biasing force in the axial direction to the plurality of parts as a whole forming the pressure sensing parts7A. Therefore, the pressure sensing parts7A as a whole are prevented from being displaced in the axial direction or falling out through the opening portion35A. That is, a locking mechanism, which is configured to prevent the plurality of parts as a whole forming the pressure sensing parts7A from being displaced in the direction orthogonal to the axial direction, is provided by the engagement between the ring-shaped locking portion36A of the cylindrical body34A and the cylindrical shape portion73Aa of the retaining member73A and the biasing force of the elastic member75.

In a state in which all of the plurality of parts forming the pressure sensing parts7A are housed and locked within the holder portion3Aa formed by the cylindrical body34A as described above, the lead portion72dof the terminal member72is soldered to the land portion8bof the printed board8, and the terminal piece75bof the elastic member75is soldered to the printed board8.

Coupled with the locking mechanism, the soldering and fixing of the lead portion72dof the terminal member72and the terminal piece75bof the elastic member75to the printed board8can more surely prevent the pressure sensing parts7A from falling out through the opening portion35A.

In this case, the dielectric71and the terminal member72are housed in a state of being unable to move in the axial direction within the hollow portion of the cylindrical body34A. On the other hand, the retaining member73A fitted with the conductive member74is movable in the axial direction within the hollow portion of the cylindrical body34A. When no pen pressure is applied, the biasing force of the elastic member75biases the retaining member73A to the side of the ring-shaped locking portion36A of the cylindrical body34A, with an air space created between the conductive member74and the dielectric71.

After the pressure sensing parts7A are housed within the cylindrical body34A forming the holder portion3Aa as described above, an anti-falling member9is press-fitted into the ring-shaped locking portion36A of the cylindrical body34A, as shown inFIGS. 8A and 8BandFIG. 9B. The anti-falling member9is coupled to the holder portion3Aa by press-fitting a cylindrical portion9bof the anti-falling member9into the ring-shaped locking portion36A of the cylindrical body34A.

Then, the ferrite core6is coupled to the holder portion3Aa of the board holder3A via the anti-falling member9. Next, the core body main body42of the core body4is inserted into a through hole6aof the ferrite core6, and an end portion of the core body main body42of the core body4is press-fitted into the recessed hole73Ab of the cylindrical shape portion73Aa of the retaining member73A housed in the holder portion3Aa. In this case, even in a state in which the core body4is press-fitted in the recessed hole73Ab of the cylindrical shape portion73Aa, the core body main body42of the core body4is also exposed from the ferrite core6to the side of the projecting member41of the core body4, as shown inFIG. 8AandFIG. 9B. A pressure (pen pressure) applied to the projecting member41of the core body4can displace the core body4toward the side of a case cap2bin the axial direction against the biasing force of the elastic member75.

As described above, the printed board8is mounted on the printed board mounting base portion3Ab of the board holder3A coupled to the case cap2b, the pressure sensing parts7A are housed in the holder portion3Aa, and the ferrite core6and the core body4are coupled to the holder portion3Aa, whereby a module part as shown inFIG. 9Bis formed.

Next, the module part is inserted into the hollow portion of the case main body2a, so that the projecting member41of the core body4projects from a through hole21of the case main body2ato the outside. Then, the case main body2aand the case cap2bare coupled to each other, whereby the position indicator1A is completed.

Pen pressure detecting operation in the position indicator1A is the same as that of the foregoing first embodiment, and therefore description thereof will be omitted here.

Effects of Second Embodiment

According to the second embodiment described above, the pen pressure detecting module can be created by housing all of the plurality of parts forming the pressure sensing parts7A into the holder portion3Aa in the direction orthogonal to the axial direction through the opening portion35A having an opening in the direction orthogonal to the axial direction, the opening portion35A being provided in the side circumferential surface of the cylindrical body34A forming the holder portion3Aa. In this case, as described above, all of the plurality of parts forming the pressure sensing parts7A are arranged in the axial direction into a unit, and the unit of the parts can be housed into the holder portion3Aa in the direction orthogonal to the axial direction through the opening portion35A in a state of being sandwiched from both sides in the axial direction of the unit of the parts. The parts can be retained in a state in which the center line position of the case2and the center line position of the pressure sensing parts7A coincide with each other, by housing the parts within the holder portion3Aa such that the parts are merely arranged along the axial direction. Hence, work efficiency in the manufacturing of the position indicator is improved.

According to the second embodiment described above, the retaining member73A among the pressure sensing parts7A in the state of being housed in the hollow portion of the cylindrical body34A is moved by the elastic member75to the side of the core body4in the axial direction, to be engaged with the ring-shaped locking portion36A and locked so as not to move in the direction orthogonal to the axial direction. Therefore, when the pressure sensing parts7A are housed within the holder portion3Aa, the locking between the retaining member73A and the ring-shaped locking portion36A against the movement of the retaining member73A in the direction orthogonal to the axial direction, coupled with the biasing force in the axial direction by the elastic member75, which biasing force is applied to all of the pressure sensing parts7A, prevents the pressure sensing parts7A from falling out (springing out) via the opening portion35A.

Hence, according to the second embodiment, a need to assemble the pen pressure detecting module by coupling each of the pressure sensing parts in the axial direction as in the prior art is eliminated. Thus, the pen pressure detecting module can be manufactured more easily, and work efficiency in the manufacturing of the position indicator is improved, so that the position indicator is suitable for mass production.

In addition, the second embodiment also provides similar effects to those of the foregoing first embodiment. In addition, the second embodiment in particular provides the following effects as compared with the case where the conventional variable capacitance capacitor described with reference toFIGS. 19A and 19Bis used as pressure sensing parts.

In the conventional variable capacitance capacitor100, the retaining member105is press-fitted into the hollow portion of the holder102. At this time, portions of the engaging holes102dand102eof the holder102, which engaging holes are brought into contact with the engaging projecting portions105dand105eprovided to the retaining member105, may be worn away or chipped, so that the position in the axial direction of the retaining member105with respect to the holder102after assembly may be varied. When such a variation occurs, a distance before contact between the conductive member106and the dielectric103may be varied, and thus the characteristics of the variable capacitance capacitor may be varied in each position indicator.

On the other hand, in the second embodiment, the retaining member73A is engaged with the ring-shaped locking portion36A by the biasing force of the elastic member75by merely inserting the retaining member73A into the cylindrical body34A forming the holder portion3Aa in the direction orthogonal to the axial direction through the opening portion35A. Therefore, unlike the position in the axial direction of the retaining member105that varies relative to the holder102in the prior art example ofFIGS. 19A and 19B, the position of the retaining member73A with respect to the holder portion3Aa does not vary, and the characteristics of the variable capacitance capacitor are not varied in each position indicator.

In addition, in the conventional variable capacitance capacitor described with reference toFIGS. 19A and 19B, the terminal member104needs to elastically hold down the dielectric103and fix the dielectric103to the holder102. The terminal member104thus needs to have a shape larger than the diameter of the dielectric103. Therefore, the conventional variable capacitance capacitor has a large size, and is difficult to be made thinner.

On the other hand, in the variable capacitance capacitor formed by the pressure sensing parts7A used in the position indicator1A according to the second embodiment, the pressure sensing parts7A are merely housed into the holder portion3Aa in the direction orthogonal to the axial direction through the opening portion35A and arranged in the axial direction, and the terminal member72can be of substantially the same shape as the dielectric71. Therefore the position indicator can be thinned easily by miniaturizing each of the plurality of parts forming the pressure sensing parts7A so as to correspond to the thinning of the position indicator.

Incidentally, also in the second embodiment described above, as in the first embodiment, the dielectric71can be more surely prevented from falling out through the opening portion35A of the holder portion3Aa by providing the terminal member72with an L-shaped projection for holding down an end portion of the dielectric71housed in the holder portion3Aa, the end portion of the dielectric71being on the side of the opening portion35A, in the direction orthogonal to the axial direction.

Third Embodiment

A third embodiment of the position indicator according to the present invention will next be described with reference toFIGS. 10 to 14. The position indicators1and1A according to the first embodiment and the second embodiment use a variable capacitance capacitor for pen pressure detection. A position indicator1B according to the third embodiment detects a change in inductance value of a coil forming a resonance circuit for pen pressure detection.

As in the first embodiment and the second embodiment, the position indicator1B according to the third embodiment is used in conjunction with a position detecting device202B included in the electronic device200shown inFIG. 2. However, in correspondence with the use of a change in inductance value of the coil of the resonance circuit for pen pressure detection by the position indicator1B according to the third embodiment, the position detecting device202B uses a pen pressure detecting method different from that of the position detecting device202. A circuit of the position indicator1B and a circuit configuration of the position detecting device202B will be described later. Incidentally, in the description of the third embodiment, the same parts as in the first embodiment and the second embodiment are identified by the same reference numerals, and detailed description thereof will be omitted. In addition, in the third embodiment, parts corresponding to the respective parts in the first embodiment and the second embodiment are identified by the same reference numerals to which a suffix B is added.

FIG. 10schematically shows the position indicator1B as a whole according to the third embodiment. As withFIG. 1AandFIG. 7Ain the first embodiment and the second embodiment described above,FIG. 10shows the inside of a case main body2Ba of a case2B of the position indicator1B with only the case main body2Ba cut away for purposes of illustration.

In the third embodiment, as in the first embodiment and the second embodiment, a board holder3B formed of a resin, for example, which board holder retains a core body4B, pressure sensing parts (pen pressure detecting parts)7B, and a printed board8B, is housed within the hollow portion of the case main body2Ba. As in the board holders3and3A according to the first embodiment and the second embodiment, an end portion in a longitudinal direction of the board holder3B is coupled to a case cap2Bb at a coupling portion3Bc of the board holder3B.

In the position indicator1B according to the third embodiment, the core body4B includes a projecting member (pen point member)41B and a ferrite core6B. The pressure sensing parts7B include a ferrite chip701, a coil spring702, and an elastic body, or a silicon rubber703in the present example. Incidentally, the ferrite core6B is an example of a first magnetic substance, and the ferrite chip701is an example of a second magnetic substance.

On a pen point side within the case main body2Ba of the position indicator1B, as shown inFIG. 10, the projecting member41B of the core body4B is housed with a portion of the projecting member41B projected through a through hole21B. The projecting member41B has a flange portion41Ba. The flange portion41Ba is engaged with a stepped portion22B formed in the portion of the through hole21B of the case main body2Ba, so that the projecting member41B is prevented from falling out through the through hole21B. Incidentally, the projecting member41B is made of a synthetic resin such as a polyacetal resin (Duracon) or the like in consideration of resistance to friction when the projecting member41B is used in a state of abutting against an operating surface.

The ferrite core6B as an example of a magnetic material, which ferrite core is wound with a coil5B as an example of an inductance element, is disposed on an opposite side from the projecting side of the projecting member41B within the case main body2Ba. The ferrite core6B in the present example has a cylindrical shape without a through hole.

The ferrite core6B forming a portion of the core body4B has a flange portion6Ba having a diameter larger than a winding portion of the coil5B on an opposite side from the side of the projecting member41B. The flange portion6Ba is locked by a pressure sensing part holder portion3Ba (which will be abbreviated to a holder portion3Ba) to be described later of the board holder3B. The ferrite core6B is thereby locked to and retained by the board holder3B.

As with the board holders3and3A in the first embodiment and the second embodiment, the board holder3B has the holder portion3Ba on the side of the core body4B and a printed board mounting base portion3Bb formed so as to be continuous with the holder portion3Ba on an opposite side from the side of the core body4B.

In the holder portion3Ba, the ferrite chip701, the coil spring702, and the silicon rubber703forming the pressure sensing parts7B are arranged in order and retained in an axial direction along a direction of going from the side of the printed board mounting base portion3Bb to the side of the core body4B. Further, a printed board8B is mounted on the printed board mounting base portion3Bb of the board holder3B.

In the position indicator1B according to the third embodiment, a side switch11, capacitors12and13, and other parts and a conductive pattern are provided on a board surface8Ba of the printed board8B as in the first embodiment and the second embodiment. However, in the third embodiment, unlike the first embodiment and the second embodiment, an IC14and a peripheral circuit thereof are not provided on the printed board8B. Incidentally, as shown inFIG. 10, also in the third embodiment, the printed board8B in a state of being mounted and locked on the printed board mounting base portion3Bb is separated from an inner wall of the case main body2Ba without being in contact with the inner wall of the case main body2Ba.

Construction of Board Holder3B and Pressure Sensing Parts7B

FIGS. 11A to 11Care diagrams of assistance in explaining the construction of portions housed within the case main body2Ba of the position indicator1B. Specifically,FIG. 11Bis a perspective view of the board holder3B. In addition,FIG. 11Ais a diagram of the parts retained by the board holder3B, the parts being shown arranged in the axial direction of the case main body2Ba. Further,FIG. 11Cis a diagram showing a state in which the ferrite core6B and the pressure sensing parts7B are housed and retained in the board holder3B and the printed board8B is disposed and locked on the board holder3B.

As shown inFIG. 11A, the parts retained by the holder portion3Ba of the board holder3B are the flange portion6Ba of the ferrite core6B (wound with the coil5B) of the core body4B and all of the plurality of parts forming the pressure sensing parts7B. The printed board8B is mounted on the printed board mounting base portion3Bb of the board holder3B.

As the pressure sensing parts7B, the silicon rubber703, the coil spring702, and the ferrite chip701are arranged in this order in the axial direction from the side of the projecting member41B of the core body4B. Incidentally, inFIG. 11A, as will be described later, a rod-shaped member704disposed next to the ferrite chip701in the axial direction is a locking member for locking the ferrite chip701of the pressure sensing parts7B to the holder portion3Ba in a state in which the center line position of the ferrite chip701and the center line position of the holder portion3Ba coincide with each other.

As shown inFIG. 11B, as with the holder portion3Aa in the second embodiment, the holder portion3Ba has a shape provided with an opening portion35B formed by cutting away, along the axial direction, an overall length of a side circumferential surface of a cylindrical body34B in a cylindrical shape corresponding to the hollow portion of the case main body2Ba. As in the second embodiment, the opening portion35B has an opening in a direction orthogonal to the axial direction of the cylindrical body34B and orthogonal to the mounting flat surface of the printed board mounting base portion3Bb of the board holder3B, on which mounting flat surface the printed board8B is mounted.

A core body locking portion36B is formed in an end portion of the cylindrical body34B forming the holder portion3Ba, which end portion is on the side of the core body4B. In addition, a part arranging portion320for arranging the pressure sensing parts7B is formed in the holder portion3Ba so as to be continuous with the core body locking portion36B.

As shown inFIG. 11B, in the third embodiment, the opening portion35B is formed over the core body locking portion36B and the part arranging portion320. In addition, an opening36Ba is made on the core body4B side of the cylindrical body34B forming the holder portion3Ba, and a wall portion37B that closes the hollow portion of the cylindrical body34B is formed at an end portion of the cylindrical body34B, which end portion is on the side of the printed board mounting base portion3Bb.

As will be described later, the flange portion6Ba of the ferrite core6B as well as the silicon rubber703, the coil spring702, and the ferrite chip701forming the pressure sensing parts7B are arranged in the axial direction, and housed in the core body locking portion36B and the part arranging portion320of the holder portion3Ba through the opening portion35B.

The printed board mounting base portion3Bb is formed between the coupling portion3Bc of the board holder3B, which coupling portion is an end portion of the board holder3B on the side of the case cap2Bb in the axial direction, and the wall portion37B of the holder portion3Ba. The printed board8B that is long and thin with a width smaller than the inside diameter of the case main body2Ba is mounted on the printed board mounting base portion3Bb. As in the first embodiment, a locking portion33B for locking the printed board8B to the printed board mounting base portion3Bb by sandwiching an end portion in a longitudinal direction of the printed board8B in a direction of thickness thereof is formed on the case cap2Bb side of the printed board mounting base portion3Bb.

Incidentally, in the third embodiment, no locking portion is formed on the wall portion37B of the cylindrical body34B forming the holder portion3Ba, which wall portion is on the side of the printed board mounting base portion3Bb. Instead, a portion of the above-described rod-shaped member704is located on the side of the printed board mounting base portion3Bb, and thereby serves also as a locking portion for sandwiching a thickness portion of an end portion of the printed board8B between the locking portion and the mounting flat surface of the printed board mounting base portion3Bb.

FIGS. 12A to 12Dare diagrams showing an example of construction of the board holder3B.FIG. 12Ais a top view of the board holder3B as viewed in a direction orthogonal to the mounting flat surface of the printed board mounting base portion3Bb.FIG. 12Bis a side view of the board holder3B as viewed in a direction parallel to the mounting flat surface of the printed board mounting base portion3Bb.FIG. 12Cis a sectional view taken along line D-D ofFIG. 12A.FIG. 12Dis a sectional view taken along line E-E ofFIG. 12C.

FIG. 13is a diagram of assistance in explaining a housed and retained state of the ferrite core6B and the pressure sensing parts7B in the core body locking portion36B and the part arranging portion320of the holder portion3Ba of the board holder3B.FIG. 13shows the holder portion3Ba in a state of the sectional view ofFIG. 12Cfor purposes of illustration.

Also in the board holder3B in the third embodiment, a flat surface3Bpn is formed along the axial direction on a side of a side circumferential surface of the cylindrical body34B forming the holder portion3Ba, which side is opposed to the opening portion35B with the axial core interposed therebetween and is opposite from the printed board mounting flat surface of the printed board mounting base portion3Bb. In this case, though not shown in detail, the flat surface3Bpn is a flush flat surface along the axial direction on the holder portion3Ba or from the holder portion3Ba to the printed board mounting base portion3Bb.

As shown inFIGS. 11A to 11C,FIGS. 12A to 12C, andFIG. 13, the inside diameter of the core body locking portion36B is selected to be slightly larger than the diameter of the portion of the ferrite core6B wound with the coil5B. The part arranging portion320is formed continuously with the core body locking portion36B. A coupling portion of the part arranging portion320, which coupling portion is coupled to the core body locking portion36B, is formed so as to have an inside diameter slightly larger than the outside diameter of the flange portion6Ba of the ferrite core6B. A stepped portion34Bc is formed at the coupling portion of the part arranging portion320, which coupling portion is coupled to the core body locking portion36B.

As shown inFIG. 13, the flange portion6Ba of the ferrite core6B is disposed on the part arranging portion320side of the core body locking portion36B. The stepped portion34Bc thereby locks the ferrite core6B so as to prevent the core body4B from falling off the holder portion3Ba in the axial direction. In addition, the part arranging portion320includes a notch for receiving the flange portion6Ba of the ferrite core6B. The ferrite core6B is formed such that an angular-range of at least 180 degrees of the flange portion6Ba of the ferrite core6B is retained in the core body locking portion36B. Therefore, the ferrite core6B is retained so as not to be detached from the core body locking portion36B and not to fall out in the direction orthogonal to the axial direction in a state in which the center line position of the ferrite core6B coincides with the center line position of the cylindrical body34B forming the holder portion3Ba.

As shown inFIG. 11A, the silicon rubber703of the pressure sensing parts7B has a projecting portion703a. As shown inFIG. 13, an end surface of the flange portion6Ba of the ferrite core6B has a recessed hole6Bb, into which to fit the projecting portion703aof the silicon rubber703. The silicon rubber703is mounted on the end surface of the flange portion6Ba of the ferrite core6B by press-fitting the projecting portion703aof the silicon rubber703into the recessed hole6Bb of the flange portion6Ba of the ferrite core6B. The outside diameter of the silicon rubber703is selected to be smaller than the diameter of the end surface of the flange portion6Ba of the ferrite core6B.

The pressure sensing parts7B are retained in the part arranging portion320such that the coil spring702forms a predetermined air space Ar between an end surface of the ferrite chip701and the silicon rubber703mounted on the end surface of the flange portion6Ba of the ferrite core6B.

For this purpose, as shown inFIGS. 11B and 11C,FIGS. 12A to 12D, andFIG. 13, the part arranging portion320has the wall portion37B that an end surface of a flange portion701aof the ferrite chip701abuts against, thus preventing the ferrite chip701from moving to the side of the printed board mounting base portion3Bb in the axial direction. A through hole320e, into which to insert the rod-shaped member704, is formed in a position of the wall portion37B, which position corresponds to the center position of the cylindrical body34B forming the holder portion3Ba.

In addition, a fitting recessed portion320ahaving an inside diameter equal to or slightly larger than the outside diameter of the flange portion701aof the ferrite chip701is formed in the part arranging portion320by a distance corresponding to the thickness of the flange portion701ain a direction of going from the wall portion37B to the side of the core body locking portion36B.

A step portion320bhaving an inside diameter equal to or slightly larger than the outside diameter of a small-diameter portion of the ferrite chip701excluding the flange portion701ais formed on the core body locking portion36B side of the fitting recessed portion320a. A portion located farther inside on the core body locking portion36B side of the step portion320bis a coil disposing portion320chaving an inside diameter equal to that of the portion whose inside diameter is made slightly larger than the flange portion6Ba of the ferrite core6B to form the stepped portion34Bc.

The length in the axial direction of the coil disposing portion320cis a length from the position of the stepped portion34Bc formed with the core body locking portion36B to the position of a stepped portion320dformed between the coil disposing portion320cand the step portion320b. The length in the axial direction of the coil disposing portion320cis such that the pressure sensing parts7B can be retained in a state in which the predetermined air space Ar is formed between the end surface of the ferrite chip701, which end surface is on the opposite side in the axial direction from the flange portion701a, and the silicon rubber703mounted on the end surface of the flange portion6Ba of the ferrite core6B, as described above.

As shown inFIG. 13, the ferrite core6B having the silicon rubber703mounted on the end surface of the flange portion6Ba is disposed on the core body locking portion36B side of the coil disposing portion320c. In addition, the flange portion701aof the ferrite chip701is fitted in the fitting recessed portion320aof the part arranging portion320in a state of abutting against the wall portion37B. The flange portion701ais made unable to move in the axial direction by a stepped portion formed by the fitting recessed portion320aand the step portion320b.

The coil spring702has a larger winding diameter than the outside diameter of the silicon rubber703. Therefore, as shown inFIG. 10andFIG. 13, one end side of the coil spring702in an elastic biasing direction abuts against the end surface of the flange portion6Ba of the ferrite core6B in a state of housing the silicon rubber703within the winding diameter of the coil spring702. Another end side of the coil spring702in the elastic biasing direction abuts against the stepped portion320dformed between the step portion320band the coil disposing portion320c. The coil spring702sets the ferrite core6B in a state of being elastically biased to the pen point side at all times and locked and retained by the core body locking portion36B.

Incidentally, in practice, the silicon rubber703is fitted and mounted on the ferrite core6B, the coil spring702is then mounted on the small-diameter portion of the ferrite chip701, and further the silicon rubber703is inserted into the winding diameter of the coil spring702, so that a unit is formed in a state in which the silicon rubber703mounted on the ferrite core6B and the end surface of the ferrite chip701are provisionally coupled to each other. The unit of the parts is sandwiched by a jig in the axial direction. In this case, the unit of the parts is sandwiched by the jig between a step portion between the flange portion6Ba of the ferrite core6B and the main body of the ferrite core6B and a head portion of the flange portion701aof the ferrite chip701.

The jig in the state of thus sandwiching the plurality of parts is inserted into the part arranging portion320of the holder portion3Ba in the direction orthogonal to the axial direction through the opening portion35B. The jig is removed, so that the above-described unit of the parts is left in the part arranging portion320. In this case, the flange portion701aof the ferrite chip701is fitted into the fitting recessed portion320a, and the coil spring702is inserted so as to abut against the end surface of the flange portion6Ba of the ferrite core6B and the stepped portion320dformed between the step portion320band the coil disposing portion320c.

Then, in the state in which the unit of the parts is inserted within the part arranging portion320, the coil spring702sets the ferrite core6B in a state of being elastically biased to the side of the core body locking portion36B at all times and retained with the air space Ar created between the silicon rubber703and the end portion of the small-diameter portion of the ferrite chip701, as shown inFIG. 10andFIG. 13.

As shown inFIG. 10andFIG. 13, a recessed hole701bis formed in the center position of the end surface of the flange portion701aof the ferrite chip701. The rod-shaped member704is fitted into the recessed hole701bthrough the through hole320eof the wall portion37B. The ferrite chip701is thereby retained such that the center line position of the ferrite chip701coincides with the center line position of the cylindrical body34B forming the holder portion3Ba.

The flange portion6Ba of the ferrite core6B is displaced to the side of the core body locking portion36B by the biasing force of the coil spring702, so that a portion of the flange portion6Ba is engaged with the inner wall surface of the core body locking portion36B. The ferrite core6B is thereby locked so as not to move in the direction orthogonal to the axial direction. The ferrite chip701is also locked so as not to move in the axial direction by the elastic biasing force of the coil spring702.

As described above, the ferrite core6B is retained by the core body locking portion36B such that the center line position of the ferrite core6B coincides with the center line position of the cylindrical body34B forming the holder portion3Ba. Thus, the parts arranged in the part arranging portion320are retained such that the center line positions of the respective parts arranged in the part arranging portion320all coincide with the center line position of the cylindrical body34B forming the holder portion3Ba.

The printed board8B is mounted on the mounting flat surface of the printed board mounting base portion3Bb of the board holder3B. At the same time, an end edge of the printed board8B on the side of the case cap2Bb in the longitudinal direction of the printed board8B is locked in a state of being sandwiched between the locking portion33B and the mounting flat surface of the printed board mounting base portion3Bb, and an end edge of the printed board8B on the side of the part arranging portion320in the longitudinal direction of the printed board8B is locked in a state of being sandwiched between the rod-shaped member704and the mounting flat surface of the printed board mounting base portion3Bb.

Further, the projecting member41B is mounted on an end of the ferrite core6B in a state in which the ferrite core6B wound with the coil5B and the pressure sensing parts7B are retained by the holder portion3Ba of the board holder3B, and the printed board8B is mounted and locked on the printed board mounting base portion3Bb as described above.

Then, also in the third embodiment, an object formed by mounting and locking the printed board8B on the printed board mounting base portion3Bb of the board holder3B, housing the pressure sensing parts7B in the holder portion3Ba and housing a portion of the ferrite core6B wound with the coil5B in the holder portion3Ba, and coupling the projecting member41B to the ferrite core6B can be handled as one module part (unit).

The module part including the board holder3B as a center is inserted into the hollow portion of the case main body2Ba, and the case main body2Ba and the case cap2Bb are coupled to each other. As a result of the above, the position indicator1B according to the third embodiment is completed.

When a user of the position indicator1B applies a pressing force (pen pressure) to the projecting member41B forming the pen point, the end surface of the flange portion6Ba of the ferrite core6B, to which the projecting member41B is coupled, is displaced and brought closer toward the side of the ferrite chip701against the biasing force of the coil spring702according to the pressing force. Then, the inductance of the coil5B changes accordingly, and the phase (resonance frequency) of a radio wave transmitted from the coil5B of the resonance circuit changes accordingly.

Further, when the pressing force is increased, the end surface of the ferrite chip701abuts against the silicon rubber703, and elastically displaces the silicon rubber703. Thereby, the inductance of the coil5B changes, and the phase (resonance frequency) of the radio wave transmitted from the coil5B of the resonance circuit changes, with a changing characteristic corresponding to the elastic modulus of the silicon rubber703.

Incidentally, in the third embodiment, the coil spring702has a smaller elastic modulus than the silicon rubber703. Specifically, letting k1be the elastic modulus of the coil spring702, and letting k2be the elastic modulus of the silicon rubber703, a relation k1<k2holds. Hence, the coil spring702is elastically deformed by a small pressing force, while the silicon rubber703is not elastically deformed unless a larger pressing force than the pressing force which is necessary to elastically deform the coil spring702is applied to the silicon rubber703.

Circuit Configuration for Position Detection and Pen Pressure Detection by Position Detecting Device202B in Third Embodiment

Next, an example of a circuit configuration in the position detecting device202B of the electronic device200that detects an indicated position and detects pen pressure using the position indicator1B according to the third embodiment described above will be described with reference toFIG. 14.FIG. 14is a block diagram showing an example of a circuit configuration of the position indicator1B and the position detecting device202B included in the electronic device200.

The position indicator1B includes a resonance circuit formed by the coil5B and the capacitors12and13. As shown inFIG. 14, the resonance circuit is formed by connecting the coil5B as an inductance element and the trimmer capacitor12formed by a chip part in parallel with each other, and further connecting in parallel a series circuit of the side switch11and the capacitor13formed by a chip part.

In this case, according to the turning on and off of the side switch11, the connection of the capacitor13to the parallel resonance circuit is controlled, and the resonance frequency changes. In addition, the inductance of the coil5B changes according to a distance relation between the ferrite chip701and the ferrite core6B, which distance relation corresponds to applied pen pressure. The resonance frequency thus changes according to the pen pressure. As will be described later, the position detecting device202B detects frequency changes by detecting changes in phase of a signal from the position indicator1B, and thus detects whether or not the side switch11is pressed and detects the pen pressure applied to the core body4B of the position indicator1B.

As with the position detecting device202in the first embodiment, the position detecting device202B of the electronic device200has a position detecting coil210formed by stacking an X-axis direction loop coil group211and a Y-axis direction loop coil group212.

In addition, the position detecting device202B has a selecting circuit213connected with the X-axis direction loop coil group211and the Y-axis direction loop coil group212. The selecting circuit213sequentially selects one loop coil of the two loop coil groups211and212.

The position detecting device202B further includes an oscillator231, a current driver232, a switching connecting circuit233, a receiving amplifier234, a detector235, a low-pass filter236, a sample and hold circuit237, an ND converter circuit238, a synchronous detector239, a low-pass filter240, a sample and hold circuit241, an A/D converter circuit242, and a processing control section243. The processing control section243is formed by a microcomputer.

The oscillator231generates an alternating-current signal of a frequency f0. The oscillator231then supplies the generated alternating-current signal to the current driver232and the synchronous detector239. The current driver232converts the alternating-current signal supplied from the oscillator231into a current, and sends out the current to the switching connecting circuit233. The switching connecting circuit233selects a connection destination (a transmitting side terminal T or a receiving side terminal R) to which to connect the loop coil selected by the selecting circuit213, under control of the processing control section243. Of the connection destinations, the transmitting side terminal T is connected with the current driver232, and the receiving side terminal R is connected with the receiving amplifier234.

An induced voltage generated in the loop coil selected by the selecting circuit213is sent to the receiving amplifier234via the selecting circuit213and the switching connecting circuit233. The receiving amplifier234amplifies the induced voltage supplied from the loop coil, and sends out the amplified induced voltage to the detector235and the synchronous detector239.

The detector235detects the induced voltage generated in the loop coil, that is, a received signal, and sends out the received signal to the low-pass filter236. The low-pass filter236has a cutoff frequency sufficiently lower than the above-mentioned frequency f0. The low-pass filter236converts the output signal of the detector235into a direct-current signal, and sends out the direct-current signal to the sample and hold circuit237. The sample and hold circuit237holds a voltage value of the output signal of the low-pass filter236in predetermined timing, specifically predetermined timing during a receiving period, and sends out the voltage value to the ND (Analog to Digital) converter circuit238. The ND converter circuit238converts the analog output of the sample and hold circuit237into a digital signal, and outputs the digital signal to the processing control section243.

Meanwhile, the synchronous detector239performs synchronous detection of the output signal of the receiving amplifier234with the alternating-current signal from the oscillator231, and sends out a signal having a level corresponding to a phase difference between the output signal of the receiving amplifier234and the alternating-current signal from the oscillator231to the low-pass filter240. The low-pass filter240has a cutoff frequency sufficiently lower than the frequency f0. The low-pass filter240converts the output signal of the synchronous detector239into a direct-current signal, and sends out the direct-current signal to the sample and hold circuit241. The sample and hold circuit241holds a voltage value of the output signal of the low-pass filter240in predetermined timing, and sends out the voltage value to the ND (Analog to Digital) converter circuit242. The ND converter circuit242converts the analog output of the sample and hold circuit241into a digital signal, and outputs the digital signal to the processing control section243.

The processing control section243controls various parts of the position detecting device202B. Specifically, the processing control section243controls the selection of a loop coil in the selecting circuit213, the switching of the switching connecting circuit233, and the timing of the sample and hold circuits237and241. The processing control section243controls a radio wave to be transmitted from the X-axis direction loop coil group211and the Y-axis direction loop coil group212for a certain transmission duration on the basis of the input signals from the ND converter circuits238and242.

A radio wave transmitted from the position indicator1B generates an induced voltage in each of loop coils of the X-axis direction loop coil group211and the Y-axis direction loop coil group212. The processing control section243calculates the coordinate values of an indicated position in the X-axis direction and the Y-axis direction, which position is indicated by the position indicator1B, on the basis of the level of the voltage value of the induced voltage generated in each of the loop coils. In addition, the processing control section243detects whether or not the side switch11is depressed and pen pressure on the basis of the level of a signal corresponding to a phase difference between the transmitted radio wave and the received radio wave.

Thus, in the position detecting device202B, the processing control section243can detect the position of the position indicator1B that has approached the position detecting device202B. In addition, the processing control section243in the position detecting device202B can detect whether or not a depression operating element16of the side switch11is depressed in the position indicator1B, and detect the pen pressure applied to the core body4B of the position indicator1B, by detecting the phase (frequency shift) of the received signal.

Effects of Third Embodiment

The third embodiment also produces similar effects to those of the first embodiment and the second embodiment described above. The third embodiment further produces the following effects.

The position indicator1B according to the third embodiment has the coil spring702and the silicon rubber703interposed between the ferrite core6B and the ferrite chip701. The ferrite core6B is thereby separated from the ferrite chip701mainly by the action of the coil spring702. Thus, even when the pen point side of the position indicator1B is directed upward, the ferrite core6B and the ferrite chip701do not come close to each other. Hence, even when the position indicator1B is handled such that the projecting member41B is directed upward, erroneous detection of pressing force does not occur.

In addition, a range of detection of the pressing force (pen pressure) applied to the core body including the projecting member41B and the ferrite core6B can be widened by the action of the coil spring702and the silicon rubber703. Moreover, the radio wave properly changing in phase (frequency) according to the pressing force can be transmitted to the position detecting device202B, and the pressing force (pen pressure) can be detected properly.

Incidentally, in the above-described example of the third embodiment, the projecting member41B of the core body4B has the flange portion41Ba and is locked to the inside of the case main body2Ba, and is thus configured to be non-replaceable. However, for example, the projecting member41B can be configured to be replaceable by providing the end portion of the ferrite core6B with a recessed portion or a projecting portion to be fitted to a projecting portion or a recessed portion provided to the projecting member41B and fitting both portions to each other.

Fourth Embodiment

Principal portions of a fourth embodiment of the position indicator according to the present invention will next be described with reference toFIGS. 15A to 15C. The position indicator1C according to the fourth embodiment is an example of a position indicator that detects pen pressure on the basis of a change in capacitance, as in the first embodiment and the second embodiment. However, in particular, in the fourth embodiment, a pressure sensing part is formed by a semiconductor device of a so-called MEMS (Micro Electro Mechanical System). In the fourth embodiment, a variable capacitance device for pressure sensing using a MEMS will be referred to as a capacitance system pressure sensing semiconductor device (hereinafter referred to as a pressure sensing device).

Also in the fourth embodiment, as in the first embodiment and the second embodiment, the position indicator1C is constructed by housing a board holder3C coupled to a case cap2bwithin a case main body2a.

FIG. 15Ais a perspective view of portions of a pressure sensing part holder portion3Ca (hereinafter abbreviated to a holder portion3Ca), in particular, of the board holder3C in the fourth embodiment and an exploded perspective view of pressure sensing parts7C.FIG. 15Bis a partial sectional view of the position indicator1C according to the fourth embodiment, showing particularly the holder portion3Ca and the vicinity thereof.FIG. 15Cis a sectional view of assistance in explaining a construction of the pressure sensing device used in the fourth embodiment, and is a sectional view taken along line F-F ofFIG. 15A.

As shown inFIG. 15A, the pressure sensing parts7C in the fourth embodiment include the pressure sensing device711, an elastic member712formed by a coil spring, and a retaining member713.

The pressure sensing device711in the present example is for example formed by sealing a pressure sensing chip800formed as a semiconductor device manufactured by MEMS technology within a package810in the form of a box as a cube or a rectangular parallelepiped, for example (seeFIGS. 15A and 15C).

The pressure sensing chip800detects pressure applied thereto as a change in capacitance. The pressure sensing chip800in the present example has a construction as shown inFIG. 15C.

The pressure sensing chip800in the present example has the shape of a rectangular parallelepiped with a longitudinal length and a lateral length of 1.5 mm and a height of 0.5 mm, for example. The pressure sensing chip800in the present example includes a first electrode801, a second electrode802, and an insulating layer (dielectric layer)803between the first electrode801and the second electrode802. The first electrode801and the second electrode802in the present example are formed by a conductor made of single crystal silicon (Si). The insulating layer803in the present example is formed by an oxide film (SiO2). Incidentally, the insulating layer803does not need to be formed by an oxide film, but may be formed by another insulator.

On a surface side of the insulating layer803, which surface side is opposed to the first electrode801, a circular recessed portion804having a center position of the surface as a center is formed in the present example. The recessed portion804forms a space805between the insulating layer803and the first electrode801. In the present example, the bottom surface of the recessed portion804is a flat surface, and has a radius of 1 mm, for example. The depth of the recessed portion804in the present example is about a few tens of microns to a few hundreds of microns.

The pressure sensing chip800in the present example is produced by a semiconductor process as follows. First, the insulating layer803made of an oxide film is formed on single crystal silicon forming the second electrode802. Next, a circular mask having a radius R is provided on the insulating layer803of the oxide film, and etching is performed, whereby the recessed portion804is formed. Then, single crystal silicon forming the first electrode801is deposited on the insulating layer803. The pressure sensing chip800having the space805under the first electrode801is thereby formed.

The presence of the space805allows the first electrode801to be displaced so as to be bent in the direction of the space805when pressed from the side of a surface801aon an opposite side from a surface opposed to the second electrode802. The thickness t of single crystal silicon as an example of the first electrode801is such that the first electrode801can be bent by a pressure applied to the first electrode801, and the thickness t is smaller than that of the second electrode802. The thickness t of the first electrode801is selected such that a bending displacement characteristic of the first electrode801in relation to the applied pressure is a desired characteristic.

In the pressure sensing chip800having the construction as described above, a capacitance Cd is formed between the first electrode801and the second electrode802. When a pressure is applied to the first electrode801from the side of the upper surface801aof the first electrode801, which upper surface is on the opposite side from the surface opposed to the second electrode802, the first electrode801is bent to the side of the space805, and a distance between the first electrode801and the second electrode802is shortened, so that the value of the capacitance Cd is changed so as to increase. An amount of bending of the first electrode801changes according to the magnitude of the applied pressure. Hence, the capacitance Cd is a variable capacitance that varies according to the magnitude of the pressure applied to the pressure sensing chip800.

Incidentally, it has been confirmed that single crystal silicon as an example of the first electrode801is bent by a few microns by a pressure, and that the capacitance of the capacitor Cd is changed by 0 to 10 pF (picofarads) according to the bending by the pressing force to this extent.

In the pressure sensing device711according to the present embodiment, the pressure sensing chip800having the construction as described above is housed within the package810in a state in which the surface801aof the first electrode801subjected to pressure is parallel to an upper surface810aof the package810and opposed to the upper surface810ainFIGS. 15A and 15C.

The package810in the present example has a shape formed by coupling a thin-plate shape portion811and a cylindrical shape portion812to each other. The package810in the present example is formed of an electrically insulative material such as a ceramic material, a resin material, or the like. As shown inFIG. 15C, the pressure sensing chip800is housed within the thin-plate shape portion811. Within the cylindrical shape portion812, an elastic member813is provided on the side of the surface801aof the pressure sensing chip800, which surface is subjected to pressure. The elastic member813is an example of a pressure transmitting member.

In the present example, a recessed portion814, which covers the area of the portion subjected to pressure in the pressure sensing chip800, is provided on the side of the surface801aof the first electrode801subjected to pressure in the pressure sensing chip800within the cylindrical shape portion812of the package810. The elastic member813is filled into the recessed portion814. The elastic member813is formed so as to be a structure integral with the package810within the recessed portion814within the cylindrical shape portion812of the package810. The elastic member813in the present example is formed of a silicon resin, particularly a silicon rubber.

A communicating hole815communicating from the upper surface810ato a portion of the elastic member813is formed in the cylindrical shape portion812of the package810. Specifically, a recessed hole forming an end portion of the communicating hole815is provided in the elastic member813within the cylindrical shape portion812. In addition, a tapered portion816is formed on an opening portion side (side of the upper surface810a) of the communicating hole815in the cylindrical shape portion812, so that the opening portion of the communicating hole815has the shape of a trumpet.

As shown inFIGS. 15A and 15C, a first lead terminal821connected to the first electrode801of the pressure sensing chip800is led out from the thin-plate shape portion811of the pressure sensing chip800, and a second lead terminal822connected to the second electrode802of the pressure sensing chip800is led out from the thin-plate shape portion811of the pressure sensing chip800. The first lead terminal821is electrically connected to the first electrode801by a gold wire823, for example. The second lead terminal822is electrically connected to the second electrode802by being led out in a state of being in contact with the second electrode802. However, the second lead terminal822and the second electrode802may of course be electrically connected to each other by a gold wire or the like.

In the present example, the first and second lead terminals821and822are formed of a conductor metal, and have a large width as shown inFIG. 15A. In the present example, the first and second lead terminals821and822are led out from the side surface of the thin-plate shape portion811, and then bent so as to be soldered on the board surface of a printed board8C mounted on a printed board mounting base portion3Cb of the board holder3C.

In addition, as shown inFIG. 15B, as will be described later, a projecting portion817for positioning the pressure sensing device711in a direction orthogonal to the axial direction of the pressure sensing device711when the pressure sensing device711is housed within the holder portion3Ca is formed on the bottom surface of the thin-plate shape portion811.

The elastic member712is formed by a coil spring whose inside diameter is larger than the diameter of the cylindrical shape portion812of the package810of the pressure sensing device711, and whose length in an elastic biasing direction is larger than the length (height) in the axial direction of the cylindrical shape portion812. As shown in the sectional view ofFIG. 15B, the elastic member712is attached so as to include the cylindrical shape portion812within the winding portion of the coil spring.

The retaining member713has a shape approximate to that of the retaining member73in the second embodiment. The retaining member713has a cylindrical shape provided with a ring-shaped swelling portion713ain a side circumferential surface. The retaining member713is provided with a ring-shaped projecting portion713b, into which to press-fit a core body main body42of a core body4on the core body4side in the axial direction of the retaining member713, and is provided with a rod-shaped projecting portion713cto be inserted into the communicating hole815of the pressure sensing device711on an opposite side in the axial direction of the retaining member713. The center line positions of the ring-shaped swelling portion713a, the ring-shaped projecting portion713b, and the rod-shaped projecting portion713care the same as the center line position of the retaining member713of a cylindrical shape. The rod-shaped projecting portion713cis to transmit pen pressure applied to the core body4to the first electrode of the pressure sensing chip800via the elastic member813within the package810of the pressure sensing device711.

The holder portion3Ca of the board holder3C has a shape approximate to that of the holder portion3awith an only difference being that the holder portion3Ca does not have the slits for housing the terminal member72in the holder portion3aof the board holder3in the first embodiment. Specifically, the holder portion3Ca has an opening portion35C that is formed in a portion of the side circumferential surface of a cylindrical body34C forming the holder portion3Ca and which has an opening in the direction orthogonal to the axial direction. The cylindrical body34C forming the holder portion3Ca has the construction of a ring-shaped locking portion36C on the core body4side in the axial direction of the cylindrical body34C.

The inside diameter of the ring-shaped locking portion36C is selected to be slightly larger than the outside diameter of the ring-shaped projecting portion713bof the retaining member713, and is selected to be smaller than the outside diameter of the ring-shaped swelling portion713aof the retaining member713. As in the first embodiment, the retaining member713is thereby regulated so as to be prevented from moving to the side of the core body4in the axial direction by the ring-shaped locking portion36C when the retaining member713is housed within the holder portion3Ca, but the retaining member713is movable to an opposite side from the side of the core body4in the axial direction.

The inside diameter of a portion where the opening portion35C of the cylindrical body34C forming the holder portion3Ca is formed is selected to be slightly larger than the outside diameter of the ring-shaped swelling portion713aof the retaining member713. A wall portion37C is formed in an end portion of the cylindrical body34C forming the holder portion3Ca, which end portion is on the side of the printed board mounting base portion3Cb, and a recessed groove38C for housing the pressure sensing device711is provided on the inside of the wall portion37C. Further, though not shown, a positioning recessed portion to be engaged with the projecting portion817provided on the bottom surface of the thin-plate shape portion811of the package810of the pressure sensing device711is formed in a flat surface of the wall portion37C, which flat surface is on the side of the recessed groove38C.

Also in the board holder3C according to the fourth embodiment, a flat surface3Cpn is formed along the axial direction on the side of the side circumferential surface of the cylindrical body34C forming the holder portion3Ca, which side is opposed to the opening portion35C with an axial position interposed therebetween and is opposite from the printed board mounting flat surface of the printed board mounting base portion3Cb. In this case, though not shown in detail, the flat surface3Cpn is a flush flat surface along the axial direction from the holder portion3Ca to the printed board mounting base portion3Cb.

Method of Housing Pressure Sensing Parts7C in Holder Portion3Ca

First, the board holder3C is mounted on the flat surface of the workbench such that the flat surface3Cpn faces the flat surface of the workbench. In this state, the board holder3C is positioned such that the opening of the opening portion35C faces in an upward direction orthogonal to the flat surface of the workbench and the printed board mounting flat surface of the printed board mounting base portion3Cb is parallel to the flat surface of the workbench, and the board holder3C is locked on the flat surface of the workbench.

Next, before the pressure sensing parts7C are housed within the hollow portion of the cylindrical body34C forming the holder portion3Ca through the opening portion35C, the elastic member712formed by the coil spring is mounted such that the cylindrical shape portion812of the package810of the pressure sensing device711is housed within the winding portion of the elastic member712. Next, the rod-shaped projecting portion713cof the retaining member713is inserted into the communicating hole815in the cylindrical shape portion812of the package810of the pressure sensing device711. In this state, the elastic member712applies an elastic biasing force in such a manner as to attempt to separate the pressure sensing device711and the retaining member713from each other in the axial direction.

Next, the pressure sensing device711, the elastic member712, and the retaining member713are sandwiched in the axial direction by a jig between the bottom surface side of the thin-plate shape portion811of the pressure sensing device711and the ring-shaped projecting portion713bof the retaining member713in such a manner as to resist the elastic biasing force of the elastic member712, whereby the pressure sensing device711, the elastic member712, and the retaining member713can be handled as a unit of parts. In this state, the pressure sensing device711, the elastic member712, and the retaining member713that can be handled as the unit of the parts are housed into the cylindrical body34C forming the holder portion3Ca through the opening portion35C. The jig is removed. At this time, the pressure sensing device711is inserted through the opening portion35C so that the pressure sensing device711is housed within the recessed groove38C, and the projecting portion817on the bottom surface of the thin-plate shape portion811is fitted into the recessed portion of the wall portion37C.

When the pressure sensing parts7C are housed within the holder portion3Ca, the ring-shaped projecting portion713bof the retaining member713is housed within the ring-shaped locking portion36C of the holder portion3Ca and the ring-shaped swelling portion713aabuts against the ring-shaped locking portion36C due to the elastic biasing force in the axial direction of the elastic member712. The retaining member713is thus prevented from moving in the direction of the core body4in the axial direction.

In this state, the elastic member712applies the biasing force in the axial direction to the plurality of parts as a whole forming the pressure sensing parts7C, and the ring-shaped locking portion36C of the cylindrical body34C prevents the ring-shaped projecting portion713bof the retaining member713from being displaced in the direction orthogonal to the axial direction. Therefore, the pressure sensing parts7C as a whole are prevented from being displaced in the axial direction or from falling out through the opening portion35C. That is, a locking mechanism for preventing the plurality of parts as a whole forming the pressure sensing parts7C from being displaced in the direction orthogonal to the axial direction is formed by the engagement between the ring-shaped locking portion36C of the cylindrical body34C and the ring-shaped projecting portion713bof the retaining member713.

In a state in which the plurality of parts as a whole forming the pressure sensing parts7C are housed and locked within the holder portion3Ca formed by the cylindrical body34C as described above, the first lead terminal821and the second lead terminal822of the pressure sensing device711are soldered to the printed board8C. Then, in this state, with the elastic member712applying the biasing force in the axial direction to the plurality of parts as a whole forming the pressure sensing parts7C, one end side in the axial direction of the pressure sensing parts7C as a whole is locked by the locking mechanism formed by the ring-shaped projecting portion713bof the retaining member713and the ring-shaped locking portion36C of the cylindrical body34C, and the first lead terminal821and the second lead terminal822of the pressure sensing device711at another end in the axial direction of the pressure sensing parts7C as a whole are fixed by the soldering to the printed board8C. Hence, in this state, the pressure sensing parts7C as a whole will not fall out through the opening portion35C.

After the pressure sensing parts7C are housed within the cylindrical body34C forming the holder portion3Ca as described above, an anti-falling member9is press-fitted into the ring-shaped locking portion36C of the cylindrical body34C, as in the first embodiment and the second embodiment. Then, an end portion of a ferrite core6is press-fitted into the anti-falling member9.

Next, in the state in which the ferrite core6is coupled to the holder portion3Ca of the board holder3C as described above, the core body main body42of the core body4is inserted into a through hole6aof the ferrite core6. Then, an end portion of the core body main body42of the core body4is press-fitted into the ring-shaped projecting portion713bof the retaining member713housed in the holder portion3Ca.

As described above, also in the fourth embodiment, the printed board8C is mounted on the printed board mounting base portion3Cb of the board holder3C coupled to the case cap2b, the pressure sensing parts7C are housed in the holder portion3Ca, and the ferrite core6and the core body4are coupled to the holder portion3Ca, whereby a module part as shown inFIGS. 4B and 9Bis formed.

Next, this module part is inserted into the hollow portion of the case main body2a, so that a projecting member41of the core body4projects from a through hole21of the case main body2ato the outside. Then, the case main body2aand the case cap2bare coupled to each other, whereby the position indicator1C is completed.

In the position indicator1C, when pressure is applied to the projecting member41of the core body4, the core body4is displaced in a direction of the inside of the case main body2ain the axial direction according to the pressure. Then, the displacement of the core body4displaces the retaining member713within the holder portion3Ca, which retaining member713is coupled with the core body main body42, toward the side of the pressure sensing device711against the elastic biasing force of the elastic member712. Then, the rod-shaped projecting portion713cof the retaining member713depresses the first electrode801of the pressure sensing chip800within the pressure sensing device711. As a result, the capacitance between the first electrode801and the second electrode802of the pressure sensing chip800changes according to the pressure applied to the core body4.

In this case, the rod-shaped projecting portion713cas a pressing member does not directly depress the surface side of the pressure sensing chip800, which surface side is subjected to the pressure, but the elastic member813is interposed between the rod-shaped projecting portion713cand the surface side of the pressure sensing chip800, which surface side is subjected to the pressure. Thus, resistance to the pressure on the surface side of the pressure sensing chip800, which surface side is subjected to the pressure, is improved, and the surface side can be prevented from being damaged by the pressure.

In addition, the rod-shaped projecting portion713cis positioned by being inserted into the communicating hole815provided in the package810of the pressure sensing chip800, and the pressure applied by the rod-shaped projecting portion713cis surely applied to the pressure sensing chip800via the elastic member813.

The pressure sensing chip800in the present example is very small as described above, and thus facilitates the thinning of the position indicator. The fourth embodiment has another advantage of a very simple construction.

In addition, the fourth embodiment provides similar effects to those of the foregoing embodiments.

Incidentally, the circuit configurations shown inFIG. 5described in the first embodiment can be used as a circuit configuration of the position indicator1C according to the fourth embodiment and a circuit configuration of the position detecting device used in conjunction with the position indicator1C.

Other Embodiments

The foregoing first to fourth embodiments use the construction of a board holder combining a pressure sensing part holder portion and a printed board mounting base portion. However, a printed board may be coupled and combined with a pressure sensing part holder portion.

FIG. 16is a diagram showing an example of such a construction formed in the second embodiment. Specifically, in the example ofFIG. 16, only a pressure sensing part holder portion30of the board holder3A described above is formed as an independent constituent part. InFIG. 16, for convenience, the same parts as in the holder portion3Aa in the second embodiment are identified by the same reference numerals.

As shown inFIG. 16, the pressure sensing part holder portion30is formed in the same manner as the holder portion3Aa described above. As described in the second embodiment, all of the pressure sensing parts7A including the dielectric71, the terminal member72, the retaining member73A, the conductive member74, and the elastic member75are housed into the pressure sensing part holder portion30in the direction orthogonal to the axial direction through the opening portion35A.

Also in the present example, a flat surface30pnis formed along the axial direction in a portion of the side circumferential surface of the cylindrical body34A forming the pressure sensing part holder portion30, the portion of the side circumferential surface of the cylindrical body34A being opposed to the opening portion35A with the axial position interposed therebetween.

A fitting recessed groove37Ab for fitting the printed board8D is formed in the pressure sensing part holder portion30. This fitting recessed groove37Ab is formed in a direction along the board surface of the printed board8D, with a width corresponding to the board thickness of the printed board8D, so that one end portion in the longitudinal direction of the printed board8D is fitted into the surface of the wall portion37A, which surface is on an opposite side from the inner side of the cylindrical body34A.

In the example ofFIG. 16, the one end portion in the longitudinal direction of the printed board8D is fitted into the fitting recessed groove37Ab of the pressure sensing part holder portion30, and coupled by bonding to the fitting recessed groove37Ab as required. In the present example, the printed board mounting base portion in the foregoing examples is not used, and another end portion in the longitudinal direction of the printed board8D is coupled and fixed to the case cap2b, for example. Also in the present example, the width (length in a direction orthogonal to the longitudinal direction) of the printed board8D is selected to be smaller than the inside diameter of the case main body2a, so that the printed board8D is not in contact with the inner wall surface of the case main body2a.

In addition, in the foregoing first to fourth embodiments, as shown inFIG. 17A, the length dx in a direction orthogonal to the axial direction of the opening portions35,35A,35B, and35C of the pressure sensing part holder portions3a,3Aa,3Ba, and3Ca is such that the pressure sensing parts7,7A,7B, and7C can be housed, as they are, into the holder portions3a,3Aa,3Ba, and3Ca through the opening portions35,35A,35B, and35C. Therefore, in the foregoing first to fourth embodiments, a locking mechanism for preventing parts of the pressure sensing parts7,7A,7B, and7C from moving in a direction orthogonal to the axial direction is provided.

However, when a resin capable of elastic displacement is used as a member forming the holder portions3a,3Aa,3Ba, and3Ca, as shown inFIG. 17B, the length in the direction orthogonal to the axial direction of the opening portions35,35A,35B, and35C of the pressure sensing part holder portions3a,3Aa,3Ba, and3Ca may be dx′, which is smaller than the length dx. Specifically, as shown inFIG. 17B, a distance between upper edge portions of a pair of wall portions351and352opposed to each other with the opening portions35,35A,35B, and35C interposed between the wall portions351and352in the direction orthogonal to the axial direction is set to be the length dx′.

In such a case, when the pressure sensing parts7,7A,7B, and7C are housed into the pressure sensing part holder portions3a,3Aa,3Ba, and3Ca through the opening portions35,35A,35B, and35C, at least a part of the pressure sensing parts7,7A,7B, and7C elastically displaces the upper edge portions of the wall portions351and352, which upper edge portions are of the opening portions35,35A,35B, and35C, in the direction orthogonal to the axial direction, so that the length of the opening portions35,35A,35B, and35C in the direction orthogonal to the axial direction is increased. All of the pressure sensing parts7,7A,7B, and7C are thereby housed within the pressure sensing part holder portions3a,3Aa,3Ba, and3Ca.

After all of the pressure sensing parts7,7A,7B, and7C are housed within the pressure sensing part holder portions3a,3Aa,3Ba, and3Ca, the wall portions351and352are elastically restored, and the distance between the upper edge portions of the wall portions351and352of the opening portions35,35A,35B, and35C is restored to the original length dx′. The movement of at least a part of the pressure sensing parts7,7A,7B, and7C in the axial direction is thereby prevented. Thus, as in the foregoing embodiments, the pressure sensing parts7,7A,7B, and7C can be prevented from falling out through the opening portions35,35A,35B, and35C.

Modifications to Foregoing Embodiments

In the foregoing first to fourth embodiments, the pressure sensing parts in a state of being housed within the pressure sensing part holder portion are locked and prevented from falling out through the opening portion by the elastic biasing force in the axial direction of the elastic member forming a part of the pressure sensing parts and the locking portion of the holder portion (the ring-shaped locking portion or the core body locking portion). However, the locking mechanism for preventing the pressure sensing parts housed in the pressure sensing part holder portion from falling out through the opening portion is not only the combination of the elastic biasing force and the locking portion described above. The pressure sensing parts can also be locked within the pressure sensing part holder portion and prevented from falling out through the opening portion by covering the opening portion with a lid portion after the pressure sensing parts are housed in the pressure sensing part holder portion. Incidentally, it is needless to say that the lid portion alone may form the locking mechanism for preventing the pressure sensing parts from falling out through the opening portion.

FIG. 18is a diagram showing an example of a construction in a case where a lid portion401for the opening portion35A is provided to the holder portion3Aa in the second embodiment. In the present example, the lid portion401is formed on an upper edge side in a direction along the axial direction of the opening portion35A so as to be rotatable on a hinge portion401awith respect to the holder portion3Aa with the hinge portion401aat the position of an axis of rotation. The lid portion401has a locking projection402formed on a side opposed to the hinge portion401a.

In the side circumferential surface of the cylindrical body34A forming the holder portion3Aa, a locking hole403is formed at a position to be engaged with the locking projection402of the lid portion401when the lid portion401is rotated with the hinge portion401aat the position of the axis of rotation and the opening portion35A is covered by the lid portion401. The shape of the locking hole403corresponds to the shape of the locking projection402. The lid portion401is locked to the holder portion3Aa in a state of closing the opening portion35A by fitting the locking projection402into the locking hole403.

According to the present example, the pressure sensing parts7A housed within the holder portion3Aa are locked within the holder portion3Aa by the lid portion401in addition to the elastic biasing force in the axial direction of the elastic member75forming a part of the pressure sensing parts and the ring-shaped locking portion36A of the holder portion3Aa. Thus, the pressure sensing parts7A are more surely prevented from falling out through the opening portion35A.

Incidentally, it is needless to say that also in the example ofFIG. 16and the example ofFIGS. 17A and 17B, a lid portion for covering the opening portion of the pressure sensing part holder portion may be similarly provided. In addition, a lid portion may be provided as a locking mechanism for preventing the pressure sensing parts from falling out through the opening portion in place of the locking portions used in all of the foregoing embodiments.

Other Modifications

Incidentally, in the foregoing first embodiment and the foregoing second embodiment, the through hole is provided in the ferrite core, and the core body main body is inserted through the through hole and fitted into the retaining member of the pressure sensing parts. However, also in the first embodiment and the second embodiment, the projecting member of the core body may be coupled to one end portion of the ferrite core as in the third embodiment, and a pressing member to be fitted into the retaining member may be coupled to the other end portion of the ferrite core. In addition, the other end portion of the ferrite core may be shaped into the form of the pressing member. In that case, as in the third embodiment, the core body includes the projecting member, the ferrite core, and the pressing member.

In addition, the foregoing third embodiment has been described supposing that the silicon rubber703is provided to the end surface of the flange portion6Ba of the ferrite core6B, but is not limited to this. The silicon rubber703may be provided to the end surface of the ferrite chip701, which end surface is opposed to the end surface of the ferrite core6B.

In addition, the circuit of the position indicator and the circuit configuration of the position detecting device in the first embodiment are as shown inFIG. 5. However, the circuit configuration shown inFIG. 14used in the third embodiment can be formed by connecting the capacitance of the variable capacitance capacitor in parallel with the coil5and using the capacitance of the variable capacitance capacitor as a part of the resonance circuit. The fourth embodiment may also similarly adopt the circuit configuration shown inFIG. 5or the circuit configuration shown inFIG. 14.