Optical fiber scanning device, optical scanning type endoscope and endoscope system

An optical fiber scanning device includes a housing, an optical fiber configured to emit light, a magnet disposed on the optical fiber, four drive coils configured to drive the optical fiber by applying to the magnet a magnetic field generated by a received drive power signal, and four detection coils configured to output an induced electromotive force signal corresponding to variation of a magnetic field, wherein the drive power signal is controlled based on the induced electromotive force signal, and four coil assemblies each including any one of the drive coils and any one of the detection coils are disposed at rotationally symmetrical positions so as to interpose the optical fiber among the four coil assemblies.

BACKGROUND OF INVENTION

1. Field of the Invention

The present invention relates to an optical fiber scanning device that includes a detection coil configured to output an induced electromotive force signal corresponding to variation of a magnetic field, and controls a drive power signal based on the induced electromotive force signal, an optical scanning type endoscope including the optical fiber scanning device at a rigid distal end portion of an insertion section of the optical scanning type endoscope, and an endoscope system including the optical scanning type endoscope.

2. Description of the Related Art

An image pickup apparatus using an image pickup device such as a CCD or a CMOS image sensor simultaneously receives reflected light from a subject by multiple light receiving elements arranged in a matrix form to acquire a subject image. In the case of an endoscope configured to photograph a dark inside of a body, an image in a range illuminated with light from a light source is acquired.

On the other hand, as for an image pickup apparatus including an optical fiber scanning device, a subject is irradiated and scanned with a light spot and reflected light from the subject is sequentially received by one light receiving element so as to create a subject image based on light reception data of the reflected light.

Japanese Patent Application Laid-Open Publication No. 2008-116922 discloses an optical fiber scanning device using magnetic force. In this optical fiber scanning device, an optical fiber having a magnet disposed on the optical fiber is arranged along a center axis of a magnetic field generating unit including a drive coil and a sensor coil arranged so as to face each other in a cylinder. Position information of the magnet, that is, a scanning state of the optical fiber is detected based on variation of a magnetic field detected by the sensor coil, and a drive signal to the drive coil is subjected to feedback control.

Note that Japanese Patent Application Laid-Open Publication No. 2014-81484 discloses an optical fiber scanning device equipped with a drive coil including a planar spiral coil formed on a board.

SUMMARY OF THE INVENTION

An optical fiber scanning device according to an embodiment includes: a housing having a cylindrical shape; an optical fiber that is arranged along a center axis of the housing and configured to emit light from a free end of the optical fiber; a magnet disposed on the optical fiber; four drive coils that are disposed in the housing and configured to drive the free end of the optical fiber by applying, to the magnet, a magnetic field generated by a received drive power signal; and four detection coils that are disposed in the housing and configured to output an induced electromotive force signal corresponding to variation of a magnetic field, wherein the drive power signal is controlled based on the induced electromotive force signal, and four coil assemblies each including any one of the drive coils and any one of the detection coils are disposed at rotationally symmetrical positions so as to interpose the optical fiber among the four coil assemblies.

An optical scanning type endoscope according to another embodiment includes an optical fiber scanning device at a rigid distal end portion of an insertion section, wherein the optical fiber scanning device includes: a housing having a cylindrical shape; an optical fiber that is arranged along a center axis of the housing and configured to emit light from a free end of the optical fiber; a magnet disposed on the optical fiber; four drive coils that are disposed in the housing and configured to drive the free end of the optical fiber by applying, to the magnet, a magnetic field generated by a received drive power signal; and four detection coils that are disposed in the housing and configured to output an induced electromotive force signal corresponding to variation of a magnetic field, the drive power signal is controlled based on the induced electromotive force signal, and four coil assemblies each including any one of the drive coils and any one of the detection coils are disposed at rotationally symmetrical positions so as to interpose the optical fiber among the four coil assemblies.

An endoscope system according to another embodiment includes: an optical scanning type endoscope including an optical fiber scanning device; a power supply configured to output a drive power signal; a correcting circuit configured to output a correction signal in which influence on induced electromotive force by a magnetic field generated by a drive coil is cancelled from an induced electromotive force signal; and a controller configured to control the power supply based on the correction signal, wherein the optical fiber scanning device includes: a housing having a cylindrical shape; an optical fiber that is arranged along a center axis of the housing and configured to emit light from a free end of the optical fiber; a magnet disposed on the optical fiber; four drive coils that are disposed in the housing and configured to drive the free end of the optical fiber by applying, to the magnet, a magnetic field generated by a received drive power signal; and four detection coils that are disposed in the housing and configured to output an induced electromotive force signal corresponding to variation of a magnetic field, the drive power signal is controlled based on the induced electromotive force signal, and four coil assemblies each including any one of the drive coils and any one of the detection coils are disposed at rotationally symmetrical positions so as to interpose the optical fiber among the four coil assemblies.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

First Embodiment

An optical fiber scanning device10of a present embodiment will be described. Note that in the following description, drawings for each embodiment are schematic, and thus the relationship between thickness and width of each portion, the ratio in thickness of respective portions, etc. are different from the actual ones. In some cases, portions having different dimensional relationship and ratios among the drawings may be contained. In addition, illustrations and representations of some components by reference signs may be omitted.

As shown inFIGS. 1 and 2, the optical fiber scanning device10includes a housing11having a cylindrical shape, an optical fiber13, a magnet12disposed on the optical fiber13, coil assemblies41to44, and an illumination optical system14. The optical fiber13is arranged along a center axis O (Z-axis direction) of the housing11.

The housing11is formed of nonmagnetic metal such as aluminum or resin. The housing11having a cylindrical shape includes a hollow portion having a square cross-section (XY plane) orthogonal to the center axis O. For example, the housing11has an outer shape ranging from not less than 1 mm to not more than 10 mm, and a wall thickness, for example, ranging from not less than 10 μm to not more than 1000 μm. The housing may be a cube having an outer surface corner portions which are subjected to curved surface processing/chamfering, or may have a circular shape.

The optical fiber13guides light from a light source unit (not shown), and emits illumination light from a free end13T2. The illumination light is applied to a subject in the form of a spot through an illumination optical system14including plural lenses.

For example, the magnet12formed of SmCo alloy is a cylindrical type, and magnetized in a longitudinal axis direction (optical-axis direction: Z-axis direction). The optical fiber13is inserted through a through-hole H15of a holding member (ferrule)15and joined. A cantilevered free end13T2of the optical fiber13in which a joint portion (fixed end13T1) to the holding member15is fixed is movable in an up-and-down direction and a right-and-left direction within the XY plane with the fixed end13T1as a base point.

The four coil assemblies41to44are disposed at rotationally symmetrical positions inside the housing11so as to interpose the optical fiber13among the four coil assemblies41to44. Note that each of the coil assemblies41to44will be hereunder referred to as a coil assembly40.

As shown inFIGS. 3, 4A and 4B, the coil assembly40includes a laminated detection coil20and drive coil30. Each of the detection coil20and the drive coil30is a planar spiral coil formed of a thin film conductor which is wound in a planar shape.

As shown inFIG. 5, the drive coil30disposed on a first coil board31includes electrode pads32S at both end portions of a winding portion32.

The planar spiral coil is fabricated, for example, by patterning using a resist mask having high accuracy according to an additive method, a subtractive method or the like. The resist mask is fabricated according to a photolithography method using a photoresist and a photomask. In the additive method, for example, a thin film conductor is formed by patterning according to a copper plating method. In the subtractive method, a conductor film is patterned by etching.

For example, the winding portion32of the spiral-shaped drive coil30which is disposed on the first coil board31formed of silicon via an insulating layer (not shown) formed of silicon oxide or the like is covered by an insulating layer32R formed of resin such as polyimide and epoxy. The insulating layer32R on the electrode pad32S includes a contact hole.

Note that in the drive coil30, the electrode pad32S is also arranged at a center portion of the winding portion32. In order to provide the electrode pad32S around the winding portion32, the drive coil30may further include a single layer of an insulating layer/lead-out wire, or may be a multi-layer coil including plural planar coils laminated via insulating layers as described later.

The electrode pad32S of the drive coil30is bonded to a bump33B of a first wiring plate33by soldering.

As shown inFIG. 4B, when receiving a drive power signal via the first wiring plate33, the drive coil30generates a magnetic field M (seeFIG. 4B) in a direction perpendicular to the plane of the coil. The magnetic field M generated by the drive coil30which is a spiral coil becomes maximum at a center C30of the winding portion32.

The detection coil20has a configuration similar to the configuration of the drive coil30. That is, the detection coil20disposed on the second coil board21includes electrode pads22S at both end portions of the detection coil20. The electrode pad22S of the detection coil20is bonded to a bump23B of a second wiring plate23by soldering.

When the magnetic field varies, the detection coil20outputs an induced electromotive force signal according to the variation of the magnetic field. The induced electromotive force signal is transmitted through the second wiring plate23.

Note that the detection coil20may have a configuration different from the configuration of the drive coil30. That is, the detection coil20does not receive large power as in the case of the drive coil30. Therefore, the detection coil20may be, for example, an aluminum thin film pattern which has larger electric resistance than the drive coil30formed of a copper plating film, and is disposed, for example, by a sputtering method. It is preferable for enhancement of the detection sensitivity that the winding number (the number of turns) of the detection coil20is larger than the winding number of the drive coil30.

In the optical fiber scanning device10, the first wiring plate33, the drive coil30, the first coil board31, the second coil board21, the detection coil20, and the second wiring plate23are laminated in this order to constitute the coil assembly40.

Note thatFIG. 4Bshows an example in which the configuration of the coil assembly40having the same configuration as the configuration ofFIG. 4Ais shown in a simplified manner. For example, the winding portion32and the like are simplified, and the center C30of the winding portion32is illustrated at the center of the drive coil30. Note that simplified illustrations are also shown inFIGS. 1 to 3which have been already used for description.

The drive coil30and the detection coil20are laminated so that the centers C30and C20of the drive coil30and the detection coil20substantially coincide with each other, and the coil board31and the coil board21are made to adhere to each other to constitute the coil assembly40. That is, the drive coil30and the detection coil20are laminated so as to be superimposed on each other.

In the optical fiber scanning device10, the coil assembly40is arranged so that the drive coil30is positioned on the center side (inside) of the housing11in order to reduce the intensity of the drive power signal. However, the coil assembly40may be arranged so that the detection coil20is positioned on the center side of the housing11.

As already described, when receiving the drive power signal, the drive coil30generates a magnetic field M in a direction perpendicular to the plane of the coil. The intensity of the magnetic field M is set by the current value of the drive power signal, the winding number (the number of turns) of the spiral coil, etc. When the direction of the drive power signal flowing in the coil is reversed, the direction of the generated magnetic field is reversed.

As shown inFIG. 2, in the optical fiber scanning device10, the four coil assemblies41to44are arranged at rotationally symmetrical positions. That is, the coil assembly41and the coil assembly42are arranged at positions facing each other, and the coil assembly43and the coil assembly44are arranged at positions facing each other.

Therefore, the drive coils30of the coil assemblies41and42generate magnetic fields in the Y-axis direction, and the drive coils30of the coil assemblies43and44generate magnetic fields in the X-axis direction.

The optical fiber13(magnet12) is arranged to be equidistant from the four drive coils30, that is, at the center of a hollow portion of the housing11.

Next, a method of driving the optical fiber scanning device10will be briefly described.

When the drive power signal is supplied to the coil assembly41(the drive coil30), for example, a magnetic field having an N-pole on the inner surface side of the coil assembly41is generated. At the same time, when the drive power signal is supplied to the coil assembly42, for example, a magnetic field having an S-pole on the inner surface side of the coil assembly42is generated. That is, the opposing coil assemblies41and42generate magnetic fields having different magnetic poles on the inner surface sides.

Therefore, for example, an N-pole end on the front side of the magnet12arranged in the magnetic field is pulled upwards in the Y-axis direction. Therefore, the free end13T2of the optical fiber13also moves upwards in the Y-axis direction.

On the other hand, when the drive power signal in the reverse direction is supplied to the coil assemblies41and42, magnetic fields having S-poles on the inner surface sides are generated. Then, the N-pole end of the magnet12is pulled downward in the Y-axis direction. Therefore, the free end of the optical fiber13also moves downwards in the Y-axis direction.

By controlling the direction of the drive power signal to be supplied to the coil assemblies41and42, that is, supplying the drive power signal which is a current-controlled AC signal, the free end of the optical fiber13scans in the Y-axis direction. Likewise, the free end of the optical fiber13scans in an X-axis direction orthogonal to the Y-axis direction by controlling the direction of the drive power signal to be supplied to the coil assemblies43and44.

The free end of the optical fiber13two-dimensionally scans within the XY plane by controlling the direction of the drive power signal to be supplied to the four coil assemblies41to44. As a result, a light spot emitted from the free end of the optical fiber13two-dimensionally scans. The scan width is controlled by the intensity of the drive power signal.

A spiral scanning method, a raster scanning method, or a lissajous method is preferable as the two-dimensional scanning method because image processing is easy, and the raster scanning method is particularly preferable because the raster scanning method can perform uniform illumination.

The magnet12and the coil assembly40may be arranged so that a driving magnetic field is applied to the rear side of the magnet12.

As shown inFIG. 6, the optical fiber scanning device10constitutes an optical fiber scanning system1X together with a power supply51, a control section (controller)52, and a correcting section (correcting circuit)53.

The drive power signal outputted from the power supply51is supplied to the drive coil30via a wire (not shown) and the first wiring plate33. On the other hand, the induced electromotive force signal outputted from the detection coil20is inputted to the correcting section53via the second wiring plate23and a wire (not shown).

The drive coil30generates a magnetic field M when receiving the drive power signal. The magnet12is driven (vibrated) by the magnetic field M. When the magnet12is driven, the optical fiber13on which the magnet12is disposed moves (scans).

The detection coil20generates an induced electromotive force signal corresponding to variation of a magnetic field. The variation of a magnetic field includes the convolution of variation of a magnetic field MM caused by movement of the magnet12disposed on the optical fiber13and variation of a magnetic field M generated by the drive coil30.

The correcting section53cancels the influence of the induced electromotive force caused by the magnetic field M generated by the drive coil30from the induced electromotive force signal outputted from the detection coil20, and outputs a correction signal which is an induced electromotive force signal based on the movement of the magnet12. The control section52controls the drive power signal outputted from the power supply51based on the output (correction signal) of the correcting section53.

For example, in the correcting section53including CPU, the output is adjusted so as to cancel the induced electromotive force signal outputted by the detection coil20under a state where the magnet12has no influence, a state where a drive power signal having a frequency at which the optical fiber13is not driven is supplied to the drive coil30. When a frequency at which the optical fiber is driven and a frequency at which this adjustment value is set are close to each other, it is little necessary to change this adjustment value even when a drive frequency changes.

For example, the control section52including CPU obtains information on a movement state of the magnet12, that is, a movement state (driving state) of the free end13T2of the optical fiber13, for example, amplitude, phase, etc. on a real-time basis from the induced electromotive force signal (correction signal) based on only the variation of the magnetic field MM caused by the movement of the magnet12disposed on the optical fiber13. The control section52controls the drive power signal outputted from the power supply51so that the optical fiber13is set to a predetermined drive state set in advance.

For example, when the amplitude of the movement (scanning) of the magnet12is smaller than a predetermined value, the control section52controls the power supply51so as to increase the absolute value of the drive power signal. Therefore, the optical fiber scanning device10can perform efficient and stable scanning irradiation.

Note that the drive coil of the coil assembly41and the drive coil of the coil assembly42which are arranged to face each other are connected in series to each other. Likewise, the drive coil of the coil assembly43and the drive coil of the coil assembly44which are arranged to face each other are connected in series to each other. Furthermore, the detection coil of the coil assembly41and the detection coil of the coil assembly42which are arranged to face each other are connected in series to each other, and the detection coil of the coil assembly43and the detection coil of the coil assembly44which are arranged to face each other are connected in series to each other.

For example, each of the detection coil20and the drive coil30shown inFIG. 6represents two coils connected in series. That is, the optical fiber scanning system10X including the four coil assemblies41to44includes two correcting sections53, two control sections52, and two power supplies51.

In the optical fiber scanning device10in which the detection coil20and the drive coil30are planar spiral coils, two detection coils20having the same configuration can be arranged in opposite positions. A detection signal outputted from the two detection coils20connected in series, that is, an induced electromotive force signal is twice as large as a detection signal outputted from one detection coil20. Furthermore, the detection signal outputted from one detection coil20increases or decreases according to the distance between the magnet12and the detection coil20even at the same moving speed of the magnet12. On the other hand, the detection signal outputted from the two detection coils20which are arranged to face each other and connected in series to each other are substantially proportional to the moving speed of the magnet12because the detection signals of the detection coils20are added to each other. Therefore, it is easy to perform the control by the control section52. Note that a method of measuring the relationship between the amplitude of the optical fiber and the detection signal in advance and performing feedback on the drive power signal by using the measurement or the like is available in order to perform more accurate control.

Needless to say, the four coil assemblies41to44may be controlled by the respective control sections52or the like. Conversely, one control section52may perform drive control in the X and Y directions, that is, control the four coil assemblies41to44. In addition, the correcting section53and the control section52may be constituted by one CPU.

In the optical fiber scanning device10, the drive coil30and the detection coil20are planar spiral coils. Therefore, the optical fiber scanning device10is smaller in diameter than a conventional optical fiber scanning device having a bulk magnetic body and a bulk conductor. Furthermore, in the optical fiber scanning device10, the coil assemblies40each including the laminated drive coil30and detection coil20can be arranged at the positions facing each other. Since the optical fiber scanning device10can apply a magnetic field to the magnet12from the drive coils located on both sides of the magnet12, the optical fiber scanning device10has a higher driving efficiency than the conventional optical fiber scanning device in which a drive coil can be arranged only on one side of a magnet.

Modification

Next, optical fiber scanning devices according to modifications of the first embodiment will be described. Since the optical fiber scanning devices according to the modifications are similar to the optical fiber scanning device10and have the same effect, the components having the same functions are represented by same reference signs, and description of these components will be omitted.

As shown inFIGS. 7A and 7B, a coil assembly40A of an optical fiber scanning device10A according to modification 1 is arranged so that the center C20of the winding portion22of the detection coil20is eccentric from the center C30of the winding portion32of the drive coil30and overlaps the winding portion32in plan view. In other words, a center line L30which passes through the center C30of the drive coil30and is orthogonal to the coil plane does not coincide with a center line L20which passes through the center C20of the detection coil20and is orthogonal to the coil plane. A central region inside the winding portion22of the detection coil20overlaps the winding portion32of the drive coil30.

That is, a cross-sectional view (FIG. 7B) of the coil assembly40A orthogonal to the optical axis is substantially identical to a cross-sectional view (for example,FIG. 4B) of the optical fiber scanning device10of the first embodiment. However, in a cross-section view parallel to the optical axis (FIG. 7A), the center C30of the drive coil30and the center C20of the detection coil20do not overlap each other.

As compared with the optical fiber scanning device10, in the optical fiber scanning device10A, the drive coil30shifts rearward in parallel to the optical axis direction with respect to the detection coil20. Conversely, in the coil assembly40A, the detection coil20may shift rearward in parallel in the optical axis direction with respect to the drive coil30.

As described above, the magnetic field M generated by the drive coil30is maximum at the center C30of the drive coil30. Then, the magnetic field M becomes extremely small just above and just below the winding portion32of the drive coil30. This is because magnetic fields generated by adjacent conductors of the winding portion32cancel each other.

The detection coil20outputs an induced electromotive force signal corresponding to variation of a magnetic field penetrating through the central region inside the winding portion22.

Therefore, the coil assembly40A which is arranged so that the center C20of the detection coil20overlaps the winding portion32of the drive coil30has a little signal component (noise component) which is contained in the induced electromotive force signal and caused by the variation of the magnetic field M generated by the drive coil30, so that a signal component generated by the variation of the magnetic field MM following the movement of the magnet12can be acquired with a higher S/N (signal/noise) ratio.

The relative positional relationship between the detection coil20and the drive coil30described above can be realized because the detection coil20and the drive coil30are planar spiral coils.

As in the case of the coil assembly40A, a coil assembly40B of an optical fiber scanning device10B according to a modification 2 is arranged so that the center C20of the detection coil20is eccentric from the center C30of the drive coil30and overlaps the winding portion32of the drive coil30in plan view.

As shown inFIGS. 8A and 8B, in the optical fiber scanning device10B, one end portion (for example, S-pole side) of the magnet12B is arranged on a line connecting the centers C30of the drive coils30which are arranged so as to face each other, and the other end portion (for example, N-pole side) of the magnet12B is arranged on a line connecting the centers C20of the detection coils20which are arranged so as to face each other.

In other words, the length L of the magnet12B is substantially equal to the distance between the center C20of the detection coil20and the center C30of the drive coil30.

In the optical fiber scanning device10B, the magnetic field M generated by the drive coil30is most strongly applied to a rear end portion of the magnet12B. On the other hand, the magnetic field MM generated by a distal end portion of the magnet12B is efficiently applied to the detection coil20.

That is, in the optical fiber scanning device10B, a driving magnetic field M generated by the drive coil30is applied to one end portion (for example, S-pole side) of the magnet12B magnetized in a longitudinal axis direction, and the magnetic field MM generated by the other end portion (for example, N-pole side) of the magnet12B is detected by the detection coil20.

The optical fiber scanning device10B has the effect of the optical fiber scanning device10A, and further is excellent in the efficiency of applying the magnetic field M to the magnet12B by the drive coil30and the detection efficiency (S/N ratio) of the magnetic field MM from the magnet12B by the detection coil20.

The distance between the center C20of the detection coil20and the center C30of the drive coil30is not necessarily required to be perfectly equal to the length L of the magnet12B, and it is possible to perform highly efficient application and detection of a magnetic field, for example, in the case where the distance ranges from not less than 0.50 L to not more than 1.50 L. In other words, it is not necessary that the position of the end portion of the magnet12B is strictly located on the line connecting the centers of the coils.

As shown inFIGS. 9A and 9B, in a coil assembly40C of an optical fiber scanning device10C according to a modification 3, the drive coil30and the detection coil20are disposed on one coil board21C. The drive coil30is disposed on a first principal surface21CA of the coil board21C, and the detection coil20is disposed on a second principal surface21CB facing the first principal surface21CA.

For example, plural coil assemblies40C can be fabricated by fragmenting, into individual pieces, a silicon wafer in which plural drive coils30are disposed on the first principal surface21CA and plural detection coils20are arranged on the second principal surface21CB facing the first principal surface21CA.

The coil assembly40C of the optical fiber scanning device10C can be easily manufactured because the drive coil30and the detection coil20are not required to be laminated while positioned. The optical fiber scanning device10C has a smaller diameter because the thickness of the coil assembly40C is smaller than the thickness of the coil assembly40.

As shown inFIGS. 10A and 10B, a coil assembly40D of an optical fiber scanning device10D according to a modification 4 is a multi-layer coil in which a drive coil30and a detection coil20disposed on a coil board21D are provided on the same principal surface21DA of one coil board21D via an insulating layer25R.

The drive coil30and the detection coil20of the coil assembly40D are connected to the same wiring plate23D. The coil assembly40D of the optical fiber scanning device10D receives a drive power signal via a wiring plate23D and transmits an induced electromotive force signal.

Plural coil assemblies40D can be fabricated, for example, by arranging plural drive coils30and plural detection coils20on one surface of a silicon wafer via insulating layers25R in a multilayer configuration and fragmenting the resultant multilayer into individual pieces.

The optical fiber scanning device10D has the effect of the optical fiber scanning device10C and further has a smaller diameter because only one wiring plate is provided.

In order to more reduce the diameter in the optical fiber scanning device10D, for example, the coil board21D may be processed to be thinner by polishing processing, or the coil board21D may be perfectly removed by etching processing which leaves only a silicon oxide layer which is an insulating layer formed on the surface of the coil board21D.

As shown inFIGS. 11A, 11B, and 11C, in a coil assembly40E of an optical fiber scanning device10E according to a modification 5, a part30E2of a drive coil30E is constituted by a multilayer wiring plate23E configured to transmit a drive power signal and an induced electromotive force signal.

A multilayer wiring plate23E on which a drive coil30E2is configured is joined to a multilayer coil including a detection coil20E disposed on the coil board21E and a drive coil30E1disposed via an insulating layer25R. End portions of the drive coil30E1and the drive coil30E2are connected to each other to constitute a two-layer coil.

The optical fiber scanning device10E has small drive power because the drive coil30is the two-layer coil, and also can be easily manufactured because the drive coil30E2is constituted by the multilayer wiring plate23E.

The detection coil arranged inside the housing11may be the two-layer coil constituted by the first detection coil on the coil board and the second detection coil on the multilayer wiring plate. For example, the detection coil may be a two-layer coil on the coil board, and the drive coil may be constituted by a multilayer wiring plate.

An optical fiber scanning device in which at least a part of a drive coil or a detection coil is constituted by a multilayer wiring plate has an effect similar to the effect of the optical fiber scanning device10E.

As shown inFIGS. 12A and 12B, in a coil assembly40F of an optical fiber scanning device10F according a modification 6, a drive coil30F and a detection coil are constituted by a multilayer wiring plate23F. The coil assembly40F contains no coil board.

At least any one of the drive coil30F and the detection coil may be a multilayer coil of two or more layers.

The optical fiber scanning device10F can be easily manufactured because the coil assembly40F is constituted by the multilayer wiring plate23F, and also has a small diameter because the optical fiber scanning device10F contains no coil board. When a flexible board is used as the multilayer wiring plate23F, the degree of freedom of the shape of the optical fiber scanning device10F is enhanced because the multilayer wiring plate can be bent, for example, so as to be wound around the optical axis.

As shown inFIG. 13, in a coil assembly40G of an optical fiber scanning device10G according to a modification 7, a drive coil30G and a detection coil20G are disposed on the same principal surface of a coil board21. The drive coil30G and the detection coil20G constitute a composite coil in which the centers of the windings of the drive coil30G and the detection coil20G are substantially coincident with each other.

The coil assembly40G of the optical fiber scanning device10G can be easily manufactured because the drive coil and the detection coil are not required to be positioned and laminated. The optical fiber scanning device10G has a small diameter because the thickness of the coil assembly40G is small.

As shown inFIG. 14, in a coil assembly40H of an optical fiber scanning device10H according to a modification 8, a drive coil30H and a detection coil20H are disposed on the same principal surface of the coil board21. The drive coil30H and the detection coil20H are disposed at different places.

The coil assembly40H of the optical fiber scanning device10H is easily manufactured because it is unnecessary to position and laminate the drive coil and the detection coil. The optical fiber scanning device10H has a small diameter because the thickness of the coil assembly40H is small.

Although not shown, when the length of the magnet is substantially equal to the distance between the center C20of the detection coil20H and the center C30of the drive coil30H, the optical fiber scanning device10H has also the same effect as the optical fiber scanning device10B which has already been described.

As shown inFIG. 15, in an optical fiber scanning device10I according to a modification 9, a yoke60formed of soft magnetic body is arranged on an outer surface side of the drive coil30and the detection coil20.

The yoke60is a magnetic field inducing section configured to induce a magnetic field generated by the drive coil30. It is preferable that the yoke60is formed of a soft magnetic material having a relative magnetic permeability of 100 or more at the frequency of the drive power signal, for example, iron, cobalt, nickel, permalloy, soft ferrite or amorphous alloy.

The optical fiber scanning device10I can drive the drive coil30with lower power because not only the magnetic field M generated by the drive coil30hardly leaks to the outside, but also the efficiency of applying the magnetic field M to the magnet12is high.

Needless to say, the housing11is formed of soft magnetic body and used as a yoke.

The optical fiber scanning devices10,10A to10I include the four coil assemblies41to44, drive the optical fiber13by using the coil assemblies41to44, and detect the driving state by the respective detection coils20of the coil assemblies41to44.

For example, even when only the two orthogonally arranged coil assemblies41and43are driven, two-dimensional scanning is possible. Furthermore, in the case of an optical fiber scanning device requiring only one-dimensional scanning, the scanning can be performed with only one coil assembly41.

Since an optical fiber scanning device10J according to a modification 10 shown inFIG. 16includes two coil assemblies41and43arranged orthogonally, the optical fiber scanning device10J can perform two-dimensional scanning. Since an optical fiber scanning device10K according to a modification 11 shown inFIG. 17includes one coil assembly41, the optical fiber scanning device10K can perform one-dimensional scanning.

The optical fiber scanning devices10C to10K would also have the same effect as the optical fiber scanning device10A when the center of the detection coil is eccentric from the center of the drive coil and arranged so as to overlap the winding of the drive coil in plan view of the coil assembly.

The optical fiber scanning devices10C to10K would also have the same effect as the optical fiber scanning device10B when one end portion of the magnet is arranged on a line connecting the centers of the detection coils which are arranged so as to face each other, and the other end portion of the magnet is arranged on a line connecting the centers of the drive coils which are arranged so as to face each other.

Second Embodiment

Next, endoscope systems1,1A to1J including optical scanning type endoscopes (endoscopes)2,2A to2J of a second embodiment will be described.

An endoscope2of the present embodiment shown inFIG. 18is an optical scanning type endoscope in which any of the optical fiber scanning devices10,10A to10K described above is equipped to a rigid distal end portion94of an insertion section91. The endoscope2having the optical fiber scanning device10will be described as an example.

An endoscope system1including the endoscope2includes the endoscope2, a main body3, and a monitor4. The endoscope2irradiates a subject with illumination light while scanning the illumination light two-dimensionally by the optical fiber scanning device10, detects reflected light (return light) from the subject, performs data processing in the main body3, and displays a generated subject image on the monitor4.

The endoscope2includes an elongated insertion section91inserted into a living body, an operation section92, and a universal cable93in which an electric cable and the like are inserted. The insertion section91of the endoscope2includes a rigid distal end portion94, a bending portion95, and a flexible tube portion96. The endoscope2of the embodiment is a so-called flexible endoscope, but has an effect described later even when the insertion section91is a hard, so-called rigid endoscope.

A bending operation knob97configured to perform a bending operation on the bending portion95is disposed on the operation section92. A connecting portion between the insertion section91and the operation section92is a grasping portion98to be gripped by a user.

The universal cable93extending from the operation section92is connected to the main body3via a connector90. The main body3is connected to the monitor4configured to display an endoscope image.

Next, the configuration of the endoscope system1is shown inFIG. 19.

A detection fiber27which is inserted from a proximal end side to a distal end side along the inner circumference of the insertion section91and guides reflected light from the subject is provided inside the insertion section91of the endoscope2. A detection optical system27A is disposed at the distal end of the detection fiber27. When the connector90of the endoscope2is connected to the main body3, the detection fiber27is connected to a demultiplexer86.

The main body3includes a drive control unit59, a memory72, an integrated control section (integrated controller)73, a light source unit74, and a detection unit76. The light source unit74has three light sources81a,81b,81cand a multiplexer82.

As described with reference toFIG. 6, the drive control unit59includes a correcting section53to which an induced electromotive force signal outputted from the detection coil20is inputted, a power supply51configured to output a drive power signal to the drive coil30, and a control section52configured to control the power supply51based on a correction signal outputted by the correcting section53.

A control program, etc. to control the overall main body3are stored in the memory72.

The integrated control section73reads out a control program from the memory72, and controls the light source unit74and the drive control unit59. The integrated control section73performs control to execute data processing on a light intensity signal of the reflected light from the subject detected by the detection unit76and display an image on the monitor4.

The light sources81a,81b, and81cof the light source unit74respectively emit light in different wavelength bands, for example, light of a wavelength band of R (red), light of a wavelength band of G (green), and light of a wavelength band of B (blue) to the multiplexer82under the control of the integrated control section73. The multiplexer82multiplexes the lights in the wavelength bands of R, G, and B, and outputs the multiplexed light to the optical fiber13.

Under the control of the integrated control section73, the drive control unit59outputs, to the drive coil30, a drive power signal with which the distal end of the optical fiber13of the optical fiber scanning device10scans in a desired scanning manner That is, the drive control unit59outputs a preset drive power signal to the coil assemblies40of the optical fiber scanning device10so as to drive the distal end of the optical fiber13in the right-and-left direction (X-axis direction) and the up-and-down direction (Y-axis direction) with respect to the insertion axis (Z-axis) of the insertion section91.

The detection fiber27receives reflected light reflected from the surface of the subject and guides the received reflected light to the demultiplexer86. The demultiplexer86is, for example, a dichroic mirror or the like, and demultiplexes the reflected light for each predetermined wavelength band. Specifically, the demultiplexer86demultiplexes the reflected light guided by the detection fiber27into reflected light of the wavelength band of R, reflected light of the wavelength band of G, and reflected light of the wavelength band of B, and outputs the three types of reflected light to detectors87a,87b, and87c, respectively.

The detectors87a,87band87care PD elements or the like configured to detect light intensities of the reflection lights in the R, G, and B wavelength bands, respectively. Signals of light intensities detected by detectors87a,87b, and87care outputted to A/D converters88a,88b, and88c, respectively. The A/D converters88ato88cconvert the analog signals of light intensities outputted from the detectors87ato87cto digital signals, and output the converted digital signals to the integrated control section73.

The integrated control section73performs predetermined image processing on the digital signals from the A/D converters88ato88cto generate a subject image, and displays the subject image on the monitor4.

Monochromatic light or a laser beam may be used as the illumination light.

Since the light scanning type endoscope2is equipped with any one of the small-diameter optical fiber scanning devices10,10A to10K each performing efficient scanning irradiation at the rigid distal end portion94of the insertion section91, the rigid distal end portion94has a small diameter and little invasive. Furthermore, since the optical fiber scanning devices10and10A to10K perform high-precision scanning irradiation, the optical scanning type endoscope2can obtain a good image. Furthermore, the optical scanning type endoscope2has low power consumption because the optical fiber scanning devices10,10A to10K can be efficiently driven.

Needless to say, the present invention is not limited to the respective forgoing embodiments, and various modifications, combinations, and applications can be made without departing from the subject matter of the invention.