Thermal head and thermal printer

A thermal head capable of reducing a possibility of separation of a connector is provided. A thermal head includes a substrate; a plurality of heat generating portions disposed on the substrate; a plurality of electrodes which are disposed on the substrate and are electrically connected to the plurality of heat generating portions, respectively; and a connector including a plurality of connector pins which pinch the substrate and are electrically connected to the plurality of electrodes, respectively, and a housing for containing the plurality of connector pins. The housing is disposed adjacent to the substrate in a sub-scanning direction, and the housing includes a support portion disposed under the substrate. This can reduce a possibility of separation of the connector.

TECHNICAL FIELD

The present invention relates to a thermal head and a thermal printer.

BACKGROUND ART

In the conventional art, various thermal heads are proposed as image printing devices such as a facsimile machine and a video printer. For example, there is known a thermal head including: a substrate; a plurality of heat generating portions disposed on the substrate; a plurality of electrodes which are disposed on the substrate and are electrically connected to the plurality of heat generating portions, respectively; and a connector including a plurality of connector pins which pinch the substrate and are electrically connected to the plurality of electrodes, respectively, and a housing for containing the plurality of connector pins (for example, see Patent Literature 1).

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

Nevertheless, in the thermal head described above, when an external force acts on the housing, a possibility arises that the connector pins separate from the electrodes so that electrical connection is cut off.

Solution to Problem

A thermal head according to one embodiment of the invention includes: a substrate; a plurality of heat generating portions disposed on the substrate; a plurality of electrodes which are disposed on the substrate and are electrically connected to the plurality of heat generating portions, respectively; and a connector including a plurality of connector pins which pinch the substrate and are electrically connected to the plurality of electrodes, respectively, and a housing for containing the plurality of connector pins. Further, the housing is disposed adjacent to the substrate in a sub-scanning direction. Furthermore, the housing includes a support portion disposed under the substrate.

A thermal head according to another embodiment of the invention includes: a substrate; a plurality of heat generating portions disposed on the substrate; a plurality of electrodes which are provided on the substrate and are electrically connected to the plurality of heat generating portions, respectively; a wiring board which is disposed adjacent to the substrate and includes a plurality of wirings electrically connected to the plurality of electrodes, respectively; and a connector including a plurality of connector pins which pinch the wiring board and are electrically connected to the plurality of wirings, respectively, and a housing for containing the plurality of connector pins. Further, the housing is disposed adjacent to the wiring board in a sub-scanning direction. Furthermore, the housing includes a support portion disposed under the wiring board.

Further, a thermal printer according to an embodiment of the invention includes: the above-mentioned thermal head; a conveying mechanism which conveys a recording medium onto the plurality of heat generating portions; and a platen roller which presses a recording medium against the plurality of heat generating portions.

Advantageous Effects of Invention

Even in a case where an external force acts on the housing, it is possible to reduce a possibility that the connector pins separate from the electrodes.

DESCRIPTION OF EMBODIMENTS

A thermal head X1is described below with reference toFIGS. 1 to 7. InFIG. 1, a protection layer25, a covering layer27, and a covering member12are shown in a simplified manner by dash-dotted lines. Further, inFIG. 3(b), the protection layer25, the covering layer27, and the covering member12are omitted. Furthermore, inFIGS. 5(a) and 5(b), the covering member12is shown in a simplified manner by a dash-dotted line.

The thermal head X1includes: a heat radiating plate1; a head base3disposed on the heat radiating plate1; and a connector31connected to the head base3.

The heat radiating plate1has a rectangular parallelepiped shape and includes a base portion1aon which a substrate7is placed. The substrate7and a housing10of the connector31are disposed on the heat radiating plate1.

For example, the heat radiating plate1is formed of a metallic material such as copper, iron, and aluminum, and has a function of radiating heat not contributing to image printing of heat generated by a heat generating portion9of the head base3. Further, the head base3is bonded to an upper face of the base portion1aby using a double-sided tape, an adhesive (not shown), or the like.

The head base3is formed in a rectangular shape in a plan view. Then, individual members constituting the thermal head X1are disposed on the substrate7of the head base3. The head base3has a function of performing printing onto a recording medium (not shown) in accordance with an electric signal supplied from the outside.

As shown inFIG. 2, the connector31includes: a plurality of connector pins8; and the housing10for containing the plurality of connector pins8. One side of the plurality of connector pins8are exposed to the outside of the housing10and the other side is contained in the inside of the housing10. The plurality of connector pins8have a function of ensuring electric conduction between various electrodes of the head base3and a power supply disposed in the outside. Then, the plurality of connector pins8are electrically independent of each other.

Each member constituting the head base3is described below.

The substrate7is disposed on the base portion1aof the heat radiating plate1, and has a rectangular shape in a plan view. Thus, the substrate7has one long side7a, the other long side7b, one short side7c, and the other short side7d. Further, a side surface7eis disposed on the other long side7bside. For example, the substrate7is formed of an electrically insulating material such as alumina ceramics or from a semiconductor material such as single crystal silicon.

A heat storage layer13is formed on an upper face of the substrate7. The heat storage layer13includes an underlayer portion13aand a ridge portion13b. The underlayer portion13ais formed over a left half of the upper face of the substrate7. Further, the underlayer portion13ais disposed in a vicinity of the heat generating portion9, and is disposed under the protection layer25described later. The ridge portion13bextends in a belt shape along the arrangement direction of a plurality of the heat generating portions9, and the cross section thereof has a substantially semi-elliptical shape. Further, the ridge portion13bhas a function of satisfactorily pressing a recording medium (not shown) onto which image printing is to be performed, against the protection layer25formed on the heat generating portion9.

The heat storage layer13is formed of glass having a low thermal conductivity, and temporarily accumulates a part of the heat generated by the heat generating portion9. Thus, the time necessary for raising the temperature of the heat generating portion9can be shortened and hence has a function of improving the heat response characteristics of the thermal head X1. For example, the heat storage layer13is formed by applying a predetermined glass paste obtained by mixing a suitable organic solvent into glass powder onto the upper face of the substrate7by screen printing or otherwise which is well known in the conventional art and then firing the glass paste.

An electric resistance layer15is disposed on an upper face of the heat storage layer13. Then, a connection terminal2, a ground electrode4, a common electrode17, an individual electrode19, a first connecting electrode21, and a second connecting electrode26are disposed on the electric resistance layer15. The electric resistance layer15is patterned in the same shape as the connection terminal2, the ground electrode4, the common electrode17, the individual electrode19, the first connecting electrode21, and the second connecting electrode26. Then, an exposed region where the electric resistance layer15is exposed is formed between the common electrode17and the individual electrode19. As shown inFIG. 1, the exposed regions of the electric resistance layer15are disposed in line on the ridge portion13bof the heat storage layer13and then each exposed region constitutes the heat generating portion9.

Although shown in a simplified manner inFIG. 1for simplicity of description, the plurality of heat generating portions9are disposed in a density of 100 to 2400 dpi (dot per inch) or the like. The electric resistance layer15is formed of a TaN-based material, TaSiO-based material, TaSiNO-based material, TiSiO-based material, TiSiCO-based material, or NbSiO-based material, or the like having a relatively high electric resistance. Thus, when a voltage is applied to the heat generating portion9, the heat generating portion9generates heat by Joule heating.

As shown inFIGS. 1 and 2, the connection terminal2, the ground electrode4, the common electrode17, the plurality of individual electrodes19, the first connecting electrode21, and the second connecting electrode26are provided on an upper face of the electric resistance layer15. The connection terminal2, the ground electrode4, the common electrode17, the individual electrodes19, the first connecting electrode21, and the second connecting electrode26are formed of a material having electrical conductivity and, for example, formed of any one kind selected from metals consisting of aluminum, gold, silver, copper, and an alloy of these.

The common electrode17includes main wiring portions17aand17d, a sub wiring portion17b, and a lead portion17c. The main wiring portion17aextends along the one long side7aof the substrate7. The sub wiring portion17bextends along each of the one short side7cand the other short side7dof the substrate7. Each lead portion17cextends individually from the main wiring portion17atoward each heat generating portion9. The main wiring portion17dextends along the other long side7bof the substrate7.

The common electrode17electrically connects the plurality of heat generating portions9to the connector31. Here, in order to reduce the electric resistance of the main wiring portion17a, the main wiring portion17amay be in the form of a thick electrode portion (not shown) thicker than the other part of the common electrode17. By virtue of this, the electric capacity of the main wiring portion17acan be increased.

The plurality of individual electrodes19electrically connect the heat generating portions9to drive ICs11. Further, the plurality of heat generating portions9are divided into a plurality of groups. Then, the individual electrodes19electrically connect each group of the heat generating portions9to each drive IC11disposed in correspondence to each group.

The plurality of first connecting electrodes21electrically connect the drive ICs11to the connector31. The plurality of first connecting electrodes21connected to each drive IC11are constructed from a plurality of wirings having different functions.

The ground electrode4is disposed so as to be surrounded by the individual electrodes19, the first connecting electrodes21, and the main wiring portion17dof the common electrode17, and has a large area. The ground electrode4is held at a ground potential of 0 to 1 V.

In order to connect the common electrode17, the individual electrodes19, the first connecting electrodes21, and the ground electrode4to the connector31, the connection terminals2are disposed on the other long side7bside of the substrate7. The connection terminals2are disposed in correspondence to the connector pins8. Then, at the time of connection to the connector31, the connection terminals2are connected to the connector pins8in a manner of being electrically independent of each other.

Each of the plurality of second connecting electrodes26electrically connects adjacent drive ICs11to each other. The plurality of second connecting electrodes26are disposed individually in correspondence to the first connecting electrodes21, and transmit various signals to adjacent drive ICs11.

The electric resistance layer15, the connection terminals2, the common electrode17, the individual electrodes19, the ground electrode4, the first connecting electrodes21, and the second connecting electrodes26described above are formed, for example, by successively laminating material layers for constituting the respective components on the heat storage layer13by a thin film forming technique such as sputtering which is well known in the conventional art and, after that, processing the laminate into a predetermined pattern by using photo-etching or the like which is well known in the conventional art. Here, the connection terminals2, the common electrode17, the individual electrodes19, the ground electrode4, the first connecting electrodes21, and the second connecting electrodes26can be formed simultaneously in the same process.

As shown inFIG. 1, each drive IC11is disposed in correspondence to each group of the plurality of heat generating portions9and connected to the other end portion of the individual electrodes19, and the one end portion of the first connecting electrodes21. The drive IC11has a function of controlling the energized state of each heat generating portion9. The drive IC11may be constructed from a switching member including a plurality of switching elements in the inside.

In a state where the drive IC11is connected to the individual electrodes19, the second connecting electrodes26, and the first connecting electrodes21, for the purpose of protection of the drive IC11and protection of the connection portion between the drive IC11and these wirings, the drive IC11is sealed with a coating resin29composed of a resin such as an epoxy resin or a silicone resin.

As shown inFIGS. 1 and 2, the protection layer25for covering the heat generating portions9, a part of the common electrode17, and a part of the individual electrodes19is formed on the heat storage layer13formed on the upper face of the substrate7.

The protection layer25has a function of protecting the covered region of the heat generating portions9, the common electrode17, and the individual electrodes19from corrosion caused by adhesion of water contained in the atmosphere or from wear caused by contact with the recording medium for image printing. The protection layer25may be formed from SiN, SiO2, SiON, SiC, diamond-like carbon, or the like. Further, the protection layer25may be constructed from a laminate of these layers. Such a protection layer25may be fabricated by using a thin film forming technique such as sputtering or a thick film forming technique such as screen printing.

Further, as shown inFIGS. 1 and 2, the covering layer27for partly covering the common electrode17, the individual electrodes19, and the first connecting electrodes21is dispsoed on the substrate7. The covering layer27has a function of protecting the covered region of the common electrode17, the individual electrodes19, the second connecting electrodes26, and the first connecting electrodes21from oxidization caused by contact with the atmosphere or from corrosion caused by adhesion of water contained in the atmosphere.

Here, in order to make the protection of the common electrode17and the individual electrodes19more definite, it is preferable that the covering layer27is formed so as to overlap with an end portion of the protection layer25as shown inFIG. 2. For example, the covering layer27may be formed of a resin material such as an epoxy resin or a polyimide resin by using a thick film forming technique such as screen printing.

The covering layer27is provided with an opening portion27afor exposing the individual electrodes19, the second connecting electrodes26, and the first connecting electrodes21to be connected to the drive IC11. Then, these wirings exposed through the opening portion27aare connected to the drive IC11. Further, in the covering layer27, an opening portion27bfor exposing the connection terminals2is disposed on the other long side7bside of the substrate7. The connection terminals2exposed through the opening portion27bare electrically connected to the connector pins8.

Next, the connector31and joining between the connector31and the head base3are described below in detail.

The connector31includes the plurality of connector pins8and the housing10for containing the plurality of connector pins8. Parts of the connector pins8are buried in the housing10.

The connector pin8includes a first connector pin8a, a second connector pin8b, a third connector pin8c, and a fourth connector pin8d. In the connector pins8, at least the first connector pin8aand the second connector pin8bare linked together by the third connector pin8cso that the first connector pin8aand the second connector pin8bform a pinching portion8e. The plurality of connector pins8are disposed with intervals in the main scanning direction. Then, adjacent connector pins8are electrically insulated from each other.

The first connector pins8ais disposed on the connection terminal2(seeFIG. 1). The second connector pin8bis disposed under the substrate7of the head base3. Then, the pinching portion8eformed by the first connector pin8aand the second connector pin8bpinches the head base3. The third connector pin8cis linked by the first connector pin8aand the second connector pin8b, and is disposed so as to extend in the thickness direction. The fourth connector pin8dis drawn out in a direction of traveling away from the head base3and provided so as to be continuous to the second connector pin8b. The pinching portion8eis formed by the first connector pin8aand the second connector pin8band then pinches the head base3so as to electrically and mechanically link the connector31to the head base3. The connector31and the head base3are linked together when the head base3is inserted into the pinching portion8eof the connector pin8.

The connector pin8need have electrical conductivity and hence may be formed of metal or an alloy. The housing10may be formed of an electrically insulating member and, for example, may be formed of resin such as PA (polyamide), PBT (poly butylene terephthalate), LCP (liquid crystal polymer), nylon 66, and glass-containing nylon 66.

The housing10has a box shape and has a function of containing the individual connector pins8in a state of being electrically independent of each other. A socket is inserted from the outside into an opening portion of the housing10. Then, electricity is provided to the head base3in association with attaching and detaching of a socket (not shown) disposed in the outside.

The housing10includes an upper wall10a, a lower wall10b, side walls10c, a front wall10d, positioning portions10f, and support portions10g. In the housing10, an opening portion is formed on the fourth connector pin8dside of the connector pins8by the upper wall10a, the lower wall10b, the side walls10c, and the front wall10d. The positioning portions10fhave a function of positioning the head base3inserted. The housing10is provided with the positioning portions10fand hence has a configuration that the head base3cannot abut against the third connector pin8cof the connector pin8. This can reduce a possibility that the connector pin8is bent or the like and hence damaged.

The support portion10gis provided in a state of protruding from the side wall10cto the underside of the substrate7. Then, the support portion10gand the substrate7are disposed apart from each other. Thus, a space14is formed between the support portion10gand the substrate7. Further, the support portion10gprotrudes from the housing10beyond the connector pins8. This can reduce a possibility that the connector pins8come into contact with the outside and hence reduce a possibility of occurrence of damage in the connector pins8.

Here, in a case where the pinching portions8eof the connector pins8pinch the substrate7so that the connector31is fixed to the head base3, when an external force (especially, a force in the vertical direction) acts on the housing10, a possibility arises that the connector pins8separate from the connection terminals2so that electrical connection is cut off.

However, the thermal head X1has a configuration that the housing10is disposed adjacent to the substrate7in the sub-scanning direction and the housing10includes the support portions10gdisposed under the substrate7. Thus, when an external force acts downward on the housing10, the support portions10gabut against the substrate7so that a downward rotational moment generated in the housing10can be alleviated. This can reduce a possibility that the connector pins8separate from the connection terminals2.

More specifically, when an external force acts downward on the housing10, a downward rotational moment is caused on the housing10about the pinching portion8ewhich is a joining portion between the substrate7and the connector31. As a result, an upward rotational moment is caused on the support portions10gso that the support portions10grotate. Then, the support portions10gabut against the substrate7so that the rotational moment generated in the support portions10gis alleviated. By virtue of this, the downward rotational moment generated in the housing10is alleviated. This can reduce a possibility that the connector31rotates, and reduce a possibility that the connector pins8separate from the connection terminals2.

Further, the protrusion length of the support portion10gfrom the housing10is longer than the protrusion length of the second connector pin8bfrom the housing10. By virtue of this, even when an external force acts on the housing10so that a downward rotational moment is caused, the support portions10geasily abut against the substrate7. As a result, the downward rotational moment generated in the housing10is alleviated and hence a possibility of rotation of the connector31can be reduced.

The thermal head X1has a configuration that the housing10has a box shape and the support portions10gare disposed on the side walls10clocated in both end portions of the housing10in the main scanning direction. Thus, the support portions10gabut against the substrate7in both end portions of the housing10in the main scanning direction.

As a result, when one support portion10gabuts against the substrate7, upward rotation of the housing10about the one support portion10gis suppressed by a situation that the other support portion10gabuts against the substrate7. By virtue of this, a possibility of vertical inclination of the housing10can be reduced.

Further, the thermal head X1has a configuration that the substrate7and the support portion10gare apart from each other and the space14is provided between the substrate7and the support portion10g. Thus, in this configuration, even when thermal expansion occurs in the support portion10g, the substrate7is not affected. This can ensure flatness in the substrate7.

The connector31and the head base3are fixed together by the connector pins8, a jointing material23, and the covering member12. As shown inFIGS. 1 and 2, the connector pins8are disposed on the connection terminal2of the ground electrode4and the connection terminals2of the first connecting electrodes21. As shown inFIG. 2, the connection terminal2and the connector pin8are mechanically and electrically connected together by the jointing material23. Then, the covering member12is disposed so as to cover the first connector pin8aof the connector31and the head base3connected by the jointing material23.

Examples of the jointing material23include solder, and anisotropy electrically conductive adhesives wherein conductive particles are mixed into an electrically insulating resin. The present embodiment is described for a case where solder is employed. The connector pin8is covered by the jointing material23and thereby electrically connected to the connection terminal2. Instead, a plating layer (not shown) composed of Ni, Au, or Pd may be provided between the jointing material23and the connection terminal2.

For example, the covering member12may be formed from an epoxy-based thermosetting resin, an ultraviolet-curing resin, or a visible-light curing resin.

Next, description is given for joining between the connector31and the head base3in a case where the covering member12is formed of a thermosetting resin.

First, in the thermal head X1, the head base3is inserted between the first connector pin8aand the second connector pin8b. At that time, the support portion10gserves as a guide for guiding a path of the head base3. The head base3is inserted up to the positioning portion10fof the housing10. The first connector pin8ais disposed on the connection terminal (not shown).

Next, the jointing material23is applied on each first connector pin8aso that the connector pin8and the head base3are connected together by the jointing material23. Then, the head base3to which the connector31has been joined is placed on the heat radiating plate1on which a double-sided tape or the like has been provided. Then, the covering member12is printed or applied by using a dispenser such that the first connector pin8amay be covered. Then, the covering member12is cured so that the thermal head X1can be fabricated.

The covering member12is disposed on the upper faces of the first connector pin8a, the upper wall10aof the housing10, the support portion10g, and the head base3. By virtue of this, the first connector pin8acan be sealed. Further, even when an external force acts upward on the connector31, the covering member12has a function of alleviating the upward rotational moment generated in the connector31so as to reduce a possibility of rotation of the connector31.

Further, the covering member12is disposed between adjacent connector pins8. This can suppress displacement of the connector31in the main scanning direction. Further, the covering member12is disposed between the side wall10cand the connector pin8. This can suppress displacement of the connector31in the main scanning direction.

Further, the covering member12is disposed in the space14surrounded by the support portion10gand the substrate7. The covering member12disposed in the space14is formed on the lower face of the head base3. By virtue of this, the joining area between the substrate7and the housing10can be increased so that the joining strength between the head base3and the housing10can be improved.

Further, even when an external force acts on the housing10so that an upward rotational moment acts on the support portion10g, since the covering member12is disposed in the space14, the pressing force acting from the support portion10gcan be alleviated so that a possibility of damage of the head base3or the support portion10gcan be reduced. Even in this case, a reaction caused by the support portion10gpressing the covering member12acts on the support portion10gso that the upward moment generated in the support portion10gcan be alleviated.

Further, the covering member12is disposed in a space16between the connector pin8and the head base3. By virtue of this, the joining area between the head base3and the housing10can be increased so that the joining strength between the head base3and the housing10can be improved.

Further, the covering member12is arranged in a space18surrounded by the substrate7, the support portion10g, and the second connector pin8badjacent to the support portion10g. By virtue of this, the joining strength between the substrate7and the support portion10gcan be improved. Further, even when an external force acts on the housing10in the right or left direction, the rightward or leftward rotational moment generated in the housing10can be alleviated by virtue of the covering member12arranged in the space18.

Further, the covering member12disposed in the space18has a shape tapered from the tip of the second connector pin8btoward the housing10. In other words, the amount of the covering member12arranged in the surroundings of the second connector pin8bgradually increases as going from the protruding tip of the second connector pin8btoward the housing10.

Thus, even when an external force acts on the housing10in the main scanning direction, a possibility that the housing10is displaced in the main scanning direction can be reduced by virtue of the covering member12disposed in the space16.

Further, the support portion10gis disposed adjacent to the side surface1bof the heat radiating plate1aand then the support portion10gis apart from the side surface1b. Thus, even when thermal expansion occurs in the support portion10g, a possibility of coming into contact with the heat radiating plate1can be reduced. This can reduces a possibility of occurrence of substrate deviation that the substrate7joined to the connector31deviates from the heat radiating plate1.

Here, in the example given above, the support portion10ghas been provided in the side wall10c. However, the support portion10gneed not necessarily be provided in the side wall10c. The substrate7and the support portion10gmay be not apart from each other. The covering member12may be not disposed between the substrate7and the support portion10g.

Next, a thermal printer Z1is described below with reference toFIG. 8.

As shown inFIG. 8, the thermal printer Z1of the present embodiment includes the above-mentioned thermal head X1, a conveying mechanism40, a platen roller50, a power supply device60, and a control device70. The thermal head X1is attached to an attaching surface80aof a mounting member80is provided in a housing (not shown) of the thermal printer Z1. Here, the thermal head X1is attached to the mounting member80along the main scanning direction defined as a direction perpendicular to the conveyance direction S of a recording medium P described later.

The conveying mechanism40includes a drive portion (not shown) and conveying rollers43,45,47, and49. The conveying mechanism40has a function of conveying in a direction of arrow S ofFIG. 8the recording medium P such as thermal paper and image receiving paper onto which ink is to be transferred and thereby conveying the recording medium P onto the protection layer25located on the plurality of heat generating portions9of the thermal head X1. The drive portion has a function of driving the conveying rollers43,45,47, and49and, for example, may be constructed from a motor. For example, the conveying rollers43,45,47, and49may be constructed such that shafts43a,45a,47a, and49aeach having a cylindrical shape and fabricated from metal such as stainless steel are covered by elastic members43b,45b,47b, and49bfabricated from butadiene rubber or the like. Here, although not shown in the figure, in a case where the recording medium P is constructed from image receiving paper onto which ink is to be transferred, an ink film, together with the recording medium P, is conveyed at a position between the recording medium P and heat generating portion9of the thermal head X1.

The platen roller50has a function of pressing the recording medium P onto a protective film25located on the heat generating portion9of the thermal head X1. The platen roller50is disposed such as to extend along a direction perpendicular to the conveyance direction S of the recording medium P. Further, both end portions of the platen roller50are rotatably supported and fixed in a state where the recording medium P is pressed onto the heat generating portion9. For example, the platen roller50may be constructed such that a shaft50ahaving a cylindrical shape and fabricated from metal such as stainless steel is covered by an elastic member50bfabricated from butadiene rubber or the like.

The power supply device60has a function of providing an electric current for causing the heat generating portion9of the thermal head X1to generate heat as described above and an electric current for causing the drive IC11to operate. The control device70has a function of supplying to the drive IC11a control signal for controlling the operation of the drive IC11for the purpose of selectively causing each heat generating portion9of the thermal head X1to generate heat as described above.

As shown inFIG. 8, in the thermal printer Z1, in a state where the platen roller50presses the recording medium P onto the heat generating portion9of the thermal head X1and in a state where the recording medium P is conveyed on the heat generating portion9by the conveying mechanism40, the power supply device60and the control device70selectively cause each heat generating portion9to generate heat so that predetermined image-printing is performed on the recording medium P. Here, in a case where the recording medium P is image receiving paper or the like, ink of an ink film (not shown) conveyed together with the recording medium P is thermal-printed to the recording medium P so that image printing is achieved in the recording medium P.

A thermal head X2is described below with reference toFIGS. 9 and 10. Here, like members to those of the thermal head X1are designated by like numerals. This convention is adopted throughout the following description.

A housing110includes an upper wall10a, a lower wall10b, side walls10c, a front wall (not shown), and support portions110g, and further includes a protruding portion110e, a cutout portion110i, and a damming portion110h. The protruding portion110eis disposed between adjacent connector pins8in a plan view. Further, the protruding portion110eis arranged also between the side wall10cand the connector pin8. The protruding portion110eextends from the front wall of the housing10to the head base3side.

The thermal head X2has a configuration that the housing110includes the protruding portion110eprotruding toward a space between adjacent first connector pins8ain a plan view. The protruding portion110emakes it possible to reduce a possibility that the covering member12flows out downward when the covering member12is applied from the upper wall10aside.

That is, the protruding portion110edams up the covering member12so that the covering member12can be stopped in the upper portion of the housing110. As a result, a possibility of shortage of the covering member12in the upper portion of the housing110can be reduced so that the connector pins8can be sealed.

Further, the protruding portion110eadjacent to the side wall10cis provided with the cutout portion110i. Thus, a space20is formed between the side wall10cand the adjacent protruding portion110ein a plan view. Thus, the thermal head X2has a configuration that the width Wa of the protruding portion110eadjacent to the side wall10cis narrower than the width Wb of the protruding portion110edisposed between adjacent first connector pins8a.

Thus, when the covering member12is applied, a part of the covering member12flows out downward though the space20. The covering member12having flowed downward spreads along the support portion110gand is then arranged in the surroundings of the support portion110g. As a result, the covering member12can be arranged in the surroundings of the support portion110gand hence the joining strength between the support portion110gand the head base3can be improved. This reduces a possibility that the connector pins8separate from the connection terminals2(seeFIG. 1).

It is preferable that the width (the length in the main scanning direction) of the cutout portion110iis 0.1 to 0.3 mm. Then, while the covering member12is restrained from flowing out downward, the first connector pins8acan be sealed by the covering member12.

It is preferable that the width Wa of the protruding portion110eis 50% to 100% of the width Wb of the protruding portion110e. Then, while a possibility that the covering member12flows out downward is reduced, the joining strength between the connector31and the substrate7in both end portions in the main scanning direction can be improved.

Further, the support portion110gincludes the damming portion110h. The damming portion110hprotrudes from the support portion110gtoward the center portion in the main scanning direction and is then connected to the lower end of the support portion110g. Thus, the support portion110gand the damming portion110hform an L-shape in sectional view as shown inFIG. 10(b).

In the thermal head X2, the support portion110gincludes the damming portion110h. Thus, the covering member12having flowed out from above can be dammed up by the damming portion110hand hence a possibility that the covering member12flow out to the outside of the connector31can be reduced. This can reduce a possibility of shortage in the amount of the covering member12.

That is, as for the covering member12having flowed out from the upper face of the housing110, a part thereof is disposed in the space14and an another part thereof is disposed on the damming portion110h. As a result, the joining strength between the support portion110gand the substrate7can be improved, and the joining strength between the damming portion110hand the substrate7can also be improved.

Further, it is preferable that the width Wc of the damming portion110his wider than the width Wa of the protruding portion110e. By virtue of this, the covering member12having flowed out from the space20can be dammed up by the damming portion110hso that outflow of the covering member12can be suppressed.

Further, it is preferable that the width Wc of the damming portion110his wider than the width Wb of the protruding portion110e. That is, it is preferable that the width Wc of the damming portion110his wider than the interval between the side wall10cand the connector pin8. By virtue of this, the covering member12having flowed out from the space20can reliably be dammed up by the damming portion110hso that outflow of the covering member12can be suppressed.

Here, description has been given for an example that the width of the cutout portion110iis shortened. Instead, the protrusion length of the cutout portion110imay be shortened. Even in this case, the covering member12can be supplied downward though the space20.

A thermal head X3is described below with reference toFIG. 11. In the thermal head X3, the shape of a connector231is different from a connector131of the thermal head X2. The other points are similar to those of the connector131and hence their description is omitted.

In a housing210, all of protruding portions210eare provided with cutout portions210i. The cutout portions210iare provided on both sides of the protruding portion210ein the main scanning direction. The cutout portions210iare individually provided on the substrate7side. Thus, a space20is formed between the substrate7and the protruding portion210e.

Even in such a case, when the covering member12is applied, a part of the covering member12flows out downward though the space20. By virtue of this, the covering member12can be supplied between the substrate7and the protruding portion210eso that the connection strength between the substrate7and the housing210can be improved.

Further, the cutout portion210iis provided in a state of being inclined relative to the connector pin8in a plan view. By virtue of this, the covering member12can efficiently be supplied to the space16between the substrate7and the connector pin8so that the connection strength between the substrate7and the housing210can be improved.

Further, in the thermal head X3, the tip of the support portion210gabuts against the side surface1bof the heat radiating plate1. This can reduce a possibility that a frictional force caused by contact with the recording medium (not shown) acts on the substrate7so that the substrate7deviates from the heat radiating plate1.

That is, when the substrate7comes into contact with the recording medium, a frictional force generated in the substrate7acts rightward inFIG. 11(b). However, by virtue of a configuration that the support portion210gabuts against the side surface1b, rightward displacement of the substrate7can be suppressed and hence a possibility of deviation of the substrate7from the heat radiating plate1can be reduced.

A thermal head X4is described below with reference toFIGS. 12 to 16. Here,FIG. 12(a)schematically shows the configuration of a head base303, a wiring board305, and a connector331. Then, a coating resin329is not shown in the figure. InFIG. 15(b), the dash-dotted line indicates a second covering member320.

The thermal head X4includes a heat radiating plate301, a head base303, a wiring board305, and a connector331. Although not shown inFIG. 12(a), individual members for causing a heat generating portion9to generate heat are provided.

In the wiring board305, wirings (not shown) are provided and the wirings are electrically connected to various electrodes of the head base303. A plurality of drive ICs311are disposed on the wiring board305. Each drive IC311is electrically connected to various electrodes of the head base303through wires and electrically connected to wirings of the wiring board305through wires.

As shown inFIG. 12(b), the coating resin329is disposed so as to cover the drive IC311and covers a part of the head base303, the drive IC311, and a part of the wiring board305. Thus, the head base303and the wiring board305are joined together by the coating resin329.

Further, in the wiring board305, the connector331is provided in the center portion thereof in the main scanning direction. Connector pins308(seeFIG. 13) of the connector331are electrically connected to the wirings of the wiring board305. Then, each connector pin308is joined by a covering member312. Here, although not shown in the figure, the connector pin308and the wiring is joined by the jointing material23similarly to the configuration of the thermal head X1. Thus, the head base303, the wiring board305, and the connector331are integrated together by the jointing material23and the covering member312.

The connector331includes a plurality of the connector pins308and a housing310for containing the plurality of connector pins308. Then, the housing310is disposed adjacent to the wiring board305in the sub-scanning direction and has support portions310gdisposed under the wiring board305.

Thus, even when an external force acts downward on the housing310, the support portions310gabut against the wiring board305so that the upward rotational moment generated in the housing310can be alleviated. This can reduce a possibility that the connector pins308separate from the wirings.

The connector pin308includes a first connector pin308a, a second connector pin308b, a third connector pin308c, and a fourth connector pin308d. In the connector pin308, the first connector pin308ato the fourth connector pin308dare formed in an integrated manner.

The first connector pin308ais disposed on the wiring of the wiring board305. The second connector pin308bis disposed under the wiring board305. Then, the first connector pin308aand the second connector pin308bpinch the wiring board305. The third connector pin308clinks together the first connector pin308aand the second connector pin308b, and is disposed so as to extend in the thickness direction of the wiring board305. The fourth connector pin308dis drawn out in a direction of traveling away from the wiring board305and joined to the housing310.

The second connector pin308bincludes a first portion308b1and a second portion308b2. The first portion308b1extends in a direction of traveling away from the third connector pin308c. The second portion308b2is provided so as to be continuous to the first portion308b1and extends in a direction of approaching the third connector pin308c, in an inclined manner relative to the first portion308b1. Further, the second portion308b2includes a contact portion308b3, and the contact portion308b3is in contact with the substrate307.

Thus, in the second connector pin308b, the first portion308b1and the second portion308b2are formed so as to be continuous to each other and the connection region between the first portion308b1and the second portion308b2has a warped shape. By virtue of this, when the wiring board305is inserted, the second connector pin308bis elastically deformed so that the wiring board305is pinched by the first connector pin308aand the second connector pin308b.

The second connector pin308bprotrudes from the wiring board305beyond the first connector pin308a. Further, the contact portion308b3is disposed on the third connector pin308cside relative to the tip of the first connector pin308a.

Thus, when the wiring board305is inserted into the connector331, the wiring board305comes into contact with the second connector pin308bbefore coming into contact with the first connector pin308a. As a result, it is possible to reduce a possibility that, in the course of insertion of the wiring board305, the first connector pin308acomes into contact with the wiring board305so that the wiring is scraped by the first connector pin308a. By virtue of this, a possibility that the first connector pin308adamages the wiring provided on the wiring board305can be reduced and hence electrical connection of the thermal head X4to the outside can be ensured.

Further, the contact portion308b3is arranged on the third connector pin308cside relative to the tip of the first connector pin308a. Thus, the first connector pin308aand the contact portion308b3can pinch the wiring board305so that the mechanical connection between the wiring board305and the connector331can be made firmer.

Further, since the second portion308b2includes the contact portion308b3, the second connector pin308bis configured to be elastically deformable. By virtue of this, at the time of insertion of the wiring board305, the second connector pin308bis deformed downward, and hence the wiring board305can be inserted in a state where the first connector pin308aand the wiring board305are apart from each other. This can reduce a possibility that the wirings of the wiring board305are damaged.

Further, the second connector pin308bis configured to be elastically deformable. Thus, even when an external force in the vertical direction acts on the housing310, the second connector pin308bcan be deformed so as to absorb the external force. By virtue of this, the rotational moment generated in the housing310can be alleviated and hence it is possible to reduce a possibility that the first connector pin308aseparates from the wiring.

As shown inFIGS. 15(a) and 15(b), in the thermal head X4, the covering member312includes a first covering member312aand a second covering member312b. The first covering member312ais provided on the first connector pin308a. The second covering member312bis disposed on the second connector pin308b. The first covering member312ais disposed so as to cover the first connector pin308a. The second covering member312bis disposed so as to expose a part of the second connector pin308b. Then, the hardness of the second covering member312bis lower than the hardness of the first covering member312a.

For example, the first covering member312amay be formed of an epoxy-based thermosetting resin. Then, it is preferable that the epoxy-based thermosetting resin has a Shore D hardness of D80to D100. Further, it is preferable that the thermal expansion coefficient is 10 to 20 ppm at ordinary temperatures.

For example, the second covering member312bmay be formed of an epoxy-based thermosetting resin. Then, it is preferable that the epoxy-based thermosetting resin has a Shore D hardness of D60to D80. Further, it is preferable that the thermal expansion coefficient is 60 to 100 ppm at ordinary temperatures.

Here, for example, the hardnesses of the first covering member312aand the second covering member312bcan be measured by using a durometer (type D) of JIS K 6253. For example, measurement by using the durometer may be performed at three arbitrary points in the first covering member312a, and then the average thereof may be adopted as the hardness of the first covering member312a. Here, a similar method may be employed also for the hardness of the second covering member312b. Further, in place of the durometer, the measurement may be performed by using a Shore hardness meter or the like.

Here, in the thermal head X4, the first connector pin308ais electrically and mechanically connected to the wiring by the jointing material23. In contrast, the second connector pin308bis merely in contact with the substrate7through the contact portion308b3and hence has merely a lower joining strength with the wiring board305in comparison with the first connector pin308a.

Further, in the connector pin308, in some cases, heat generated at the time of drive of the thermal head X4causes thermal expansion in the housing310and hence deformation may be caused in the connector pin308. At that time, since the first connector pin308ais fixed to the wiring by the jointing material23, in this configuration, the second connector pin308bis easily deformed. Thus, in some cases, separation may occur in the second covering member312blocated in the surroundings of the second connector pin308b.

In contrast, the thermal head X4has such a configuration that the hardness of the second covering member312bis lower than the hardness of the first covering member312a. Thus, even when thermal expansion occurs in the connector pin308, since the hardness of the second covering member312blocated in the surroundings of the second connector pin308bis lower than the hardness of the first covering member312a, the second covering member312bcan follow the deformation of the second connector pin308b.

As a result, the stress generated in the inside of the second covering member312bcan be alleviated and hence a possibility that separation occurs in the second covering member312bcan be reduced. Accordingly, the joining strength of the connector331can be ensured. Thus, a possibility that the connector331separates from the wiring board305can be reduced.

Further, in the thermal head X4, the first covering member312acovers the first connector pin308a, and the second covering member312bis disposed on the second connector pin308bin a state where a part of the second connector pin308bis exposed. Thus, the deformation of the second connector pin308bis less likely to be blocked, and hence the stress generated in the second covering member312bcan be alleviated.

Here, electrical connection of the thermal head X4to the outside is achieved by attaching and detaching a socket to and from the opening portion of the housing310. At the time of attaching and detaching of the socket, an external force acts on the housing310in the thickness direction, the sub-scanning direction, or the main scanning direction. Thus, a possibility arises that the housing310is damaged. In particular, when the socket is extracted from the housing310, a strong external force easily acts on the housing310in the main scanning direction.

In contrast, in the thermal head X4, as shown inFIG. 15(a), the first covering member312aincludes: a first portion312a1disposed on the housing310; and a second portion312a2protruding from the first portion312a1in a direction of traveling away from the wiring board305in a plan view.

Thus, the thickness of the upper face310aof the housing310can be reinforced by the thickness of the second portion312a2. As a result, the second portion312a2can reinforce the housing310. Thus, even when an external force acts on the housing310, a possibility that the housing310is damaged can be reduced. As a result, a possibility that the connector331is damaged can be reduced.

Further, the thermal head X4has such a configuration that each end portion of the housing310in the main scanning direction is provided with the second portion312a2. Thus, the second portion312a2can reinforce each end portion of the housing310in the main scanning direction. Thus, when the socket is extracted from the housing310, a possibility that the housing310is damaged can be reduced.

The second covering member312bis disposed on the second connector pin308band disposed so as to extend in the main scanning direction. The second covering member312bis disposed so as to cover the contact portion308b3of the second connector pin308band is disposed in a state where the first portion308b1of the second connector pin308bis exposed.

Further, the second covering member312bis disposed between the support portion310gand the wiring board305. By virtue of this, the joining strength between the wiring board305and the connector331can be improved.

Further, the second covering member312bis disposed between the support portion310gand the heat radiating plate301and the housing310abuts against the heat radiating plate301. That is, in the thermal head X4, the housing310is arranged adjacent to the side surface301eof the heat radiating plate310and the support portion310gand the side surface301eare connected together by the second covering member312b.

By virtue of this, even when a frictional force acts on the head base303in accordance with conveyance of the recording medium, since the housing310abuts against the heat radiating plate301, a possibility of occurrence of position deviation of the head base303can be reduced.

Further, the housing310is in contact with the side surface301bof the heat radiating plate301with the second covering member312bin between. Thus, in the main scanning direction, position deviation of the housing310from the heat radiating plate301is less likely to occur. Thus, even when an external force acts on the housing310, a possibility of position deviation of the housing310in the main scanning direction can be reduced.

Further, the second covering member312bjoins together the support portion310gand the side surface301b. This can reduce an internal stress in the housing310caused by a difference in the thermal expansion coefficients of the housing310and the heat radiating plate301. By virtue of this, the amount of deformation generated in the housing310can be reduced. As a result, a possibility that the housing310is damaged can be reduced.

Joining of the individual members of the thermal head X4is described below.

First, the connector331and the wiring board305are joined together by using the jointing material23. Then, in order to covering the first connector pin308aand wiring, the first covering member312ais applied by screen printing or by using a dispenser, and then dried. Then, in a state where the second covering member312bhas been applied to the end face of the support portion310gof the connector331, in a manner that the support portion310gmay come into contact with the side surface301bof the heat radiating plate301, the wiring board305is placed on the heat radiating plate301on which a double-sided tape or the like has been disposed.

After that, the head base303is placed on the heat radiating plate301so as to be adjacent to the wiring board305. Then, the wiring board305and the head base303are electrically connected together through wires by a wire bonding method.

After that, the coating resin329is applied so as to cover the drive IC311by printing or by using a dispenser, and then cured. Here, such a method may be employed that the head base303and the wiring board305are joined to the heat radiating plate301and, after that, the first covering member312aand the second covering member312bare applied and then cured.

Embodiments of the invention has been described above. However, the invention is not limited to the embodiments given above, and various changes are possible without departing from the scope of the invention. For example, description has been given for the thermal printer Z1employing the thermal head X1according to the first embodiment. However, employable configurations are not limited to this, and the thermal head X2to X4may be employed in the thermal printer Z1. Further, thermal heads X1to X4according to a plurality of the embodiments may be combined together.

In the thermal heads X1to X4, description has been given for an example that the connector31is disposed in the center portion in the arrangement direction. Instead, the connector31may be disposed in each end portion in the arrangement direction.

Further, description has been given for an example that the support portion10ghas a rectangular shape in a side view. However, the shape may be not rectangular. For example, the support portion10gmay have a semi-circular shape or a semi-elliptical shape in a side view. Further, a corner of the support portion10ghaving a rectangular shape may be chamfered in a C-shape or an R-shape. In these cases, at the time that the head base3is inserted into the connector31, a possibility of occurrence of a flaw in the head base3can be reduced.

Further, the ridge portion13bmay be not formed in the heat storage layer13, and then the heat generating portion9of the electric resistance layer15may be disposed on the underlayer portion13aof the heat storage layer13. Further, the heat storage layer13may be provided over the entirety of the upper face of the substrate7.

Further, the common electrode17and the individual electrode19may be formed on the heat storage layer13, and then the electric resistance layer15may be formed only in a region between the common electrode17and the individual electrode19so that the heat generating portion9may be constructed.

Further, description has been given for an example of a thin film head having a thin heat generating portion9in which the electric resistance layer15is fabricated by thin film formation. However, employable configurations are not limited to this. For example, the invention may be applied to a thick film head having a thick heat generating portion9in which after the patterning of the various electrodes, the electric resistance layer15is fabricated by thick film formation. Further, the present technology may be applied to an end face head in which the heat generating portion9is formed in an end face of the substrate.

Here, the coating resin29and the covering member12may be fabricated from the same material. In this case, at the time of printing of the coating resin29, the printing may be performed also in the region where the covering member12is to be formed, so that the coating resin29and the covering member12may simultaneously be formed.

REFERENCE SIGNS LIST

X1-X4: Thermal head

Z1: Thermal printer

1: Heat radiating plate

3: Head base

8a: First connector pin

8b: Second connector pin

8c: Third connector pin

8d: Fourth connector pin

9: Heat generating portion

10a: Upper wall

10b: Lower wall

10c: Side wall

10d: Front wall

10g: Support portion

11: Drive IC

12: Covering member

13: Heat storage layer

15: Electric resistance layer

21: First connecting electrode

25: Protection layer

26: Second connecting electrode

27: Covering member