JP2011245762A - Thermal head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce density unevenness of print due to a thermal head by reducing a voltage drop in a wiring conductor of a printed wiring board.SOLUTION: The thermal head X includes: a head base body 3 having a substrate 9 and a plurality of heating parts 11 arranged on the substrate 9; and a multilayered printed wiring board 5 extending along an arranged direction of the heating parts 11 for supplying current to the heating parts 11. The heating parts 11 are electrically connected in common to a first layer low electrical potential wiring conductor 33 extending along the arranged direction of the heating parts 11. Second low electrical potential wiring conductors 39 arranged mutually separated along the arranged direction of the heating parts 11 are connected in common to one first low electrical potential wiring conductor 33 by a plurality of conductive connectors 43 piercing an electrically insulating layer 23.

Description

  The present invention relates to a thermal head.

  Conventionally, various thermal heads have been proposed as printing devices such as facsimiles and video printers. For example, the thermal head described in Patent Document 1 extends along the arrangement direction of a head base having a plurality of heat generating parts (heat generating elements) arranged on a substrate (ceramic substrate) and the heat generating parts. And a flexible printed wiring board for supplying a current to the heat generating portion. This flexible printed wiring board has a wiring conductor extending along the arrangement direction of the heat generating portions. The wiring conductor is connected to a connector, and is electrically connected to an external power supply device via the connector.

JP 9-48148 A

  In the thermal head described in Patent Document 1, a current is supplied to the plurality of heat generating parts via the wiring conductor extending along the arrangement direction of the heat generating parts as described above. For this reason, in this wiring conductor, the voltage drop increases as the distance from the connection portion with the connector increases, and the magnitude of the current supplied to each heat generating portion may vary. As a result, the heat generation temperature of each heat generating portion varies, and there is a problem that the print density by the thermal head may be uneven.

  The present invention has been made in order to solve the above-described problem, and an object of the present invention is to reduce a voltage drop in a wiring conductor of a printed wiring board and to reduce density unevenness of a print by a thermal head.

A thermal head according to an embodiment of the present invention includes a substrate, a head base having a plurality of heat generating parts arranged on the substrate, and extends in the arrangement direction of the heat generating parts. A multilayer printed wiring board for supplying the multilayer printed wiring board, the multilayer printed wiring board having a first printed wiring layer and a second printed wiring layer laminated via an electrical insulating layer, and in the arrangement direction of the heat generating portions A plurality of connection wirings arranged along one edge extending along the edge and electrically connected to the heat generating portion, wherein the first printed wiring layer extends in the arrangement direction of the heat generating portions. A first-layer low-potential wiring conductor, and a first-layer low-potential wiring conductor formed so as to surround the first-layer low-potential wiring conductor; Wiring conductor to external power supply A low-potential connection region for air connection, and the first-layer high-potential wiring conductor is disposed on both sides of the first-layer low-potential wiring conductor in a direction orthogonal to the arrangement direction of the heat generating portions. , Having a first connection region and a second connection region extending along the arrangement direction of the heat generating portions, and formed in the first connection region, and electrically connecting the first layer high potential wiring conductor to an external power supply device Having a high potential connection region for connection, the second printed wiring layer has a plurality of second layer low potential wiring conductors spaced apart from each other along the arrangement direction of the heat generating portions, The plurality of connection wirings include a plurality of first connection wirings connected to the second connection region of the first layer high potential wiring conductor and a plurality of second connection wirings connected to the second layer low potential wiring conductor. And via the first connection wiring Said serial plurality of heat generating portions first
The plurality of heat generating portions are electrically connected to the plurality of second layer low potential wiring conductors via the second connection wiring, and are electrically connected in common to the second connection regions of the layer high potential wiring conductors. The plurality of second-layer low-potential wiring conductors are commonly connected to one first-layer low-potential wiring conductor by a plurality of conductive connectors that penetrate the electrical insulating layer. Thermal head characterized by being.

  In the thermal head according to an embodiment of the present invention, the second printed wiring layer is positioned along the arrangement direction of the heat generating portions at a position corresponding to the first connection region of the first layer high potential wiring conductor. A second-layer high-potential wiring conductor having a main wiring section extending and a sub-wiring section extending between the adjacent second-layer low-potential wiring conductors in a direction orthogonal to the arrangement direction of the heat generating sections; The main wiring portion is connected to the first connection region of the first-layer high-potential wiring conductor by a plurality of conductive connectors that penetrate the electrical insulating layer, and the sub-wiring portion has one end that is The other end may be connected to the second connection region of the first-layer high-potential wiring conductor via a conductive connection body that is connected to the main wiring portion and penetrates the electrical insulating layer.

  In the thermal head according to an embodiment of the present invention, the sub-wiring portion may be wider as the sub-wiring portion is located farther from the high potential connection region.

  In the thermal head according to an embodiment of the present invention, the arrangement density of the sub-wiring portions may increase as the distance from the high potential connection region increases.

  According to the present invention, it is possible to reduce the voltage drop in the wiring conductor of the printed wiring board and reduce the density unevenness of the print by the thermal head.

It is a top view which shows one Embodiment of the thermal head of this invention. It is the II-II sectional view taken on the line of the thermal head of FIG. It is a rear view of the multilayer printed wiring board of the thermal head of FIG. It is a rear view which shows the modification of the multilayer printed wiring board shown in FIG. It is a rear view which shows the modification of the multilayer printed wiring board shown in FIG.

  Hereinafter, an embodiment of a thermal head of the present invention will be described with reference to the drawings. As shown in FIGS. 1 and 2, the thermal head X of the present embodiment includes a radiator 1, a head substrate 3 disposed on the radiator 1, and a multilayer printed wiring board 5 ( (Hereinafter referred to as PWB5) and a connector 7 connected to the PWB5.

  The radiator 1 is formed in a plate shape and has a rectangular shape in plan view. The radiator 1 is made of, for example, a metal material such as copper or aluminum, and has a function of radiating a part of heat that does not contribute to printing out of heat generated in a heat generating portion 11 of the head base 3 to be described later. Have.

  A head substrate 3 is bonded to the upper surface of the radiator 1 by a double-sided tape, an adhesive, or the like (not shown). The head base 3 has a rectangular substrate 9 in plan view, a plurality of (in the illustrated example, 56) heat generating units 11 provided on the substrate 9 and arranged along the longitudinal direction of the substrate 9, and the heat generating unit 11. And a plurality (seven in the illustrated example) of driving ICs 15 arranged side by side on the substrate 9 along the arrangement direction of the heat generating portions 11.

  The substrate 9 is formed of an electrically insulating material such as alumina ceramic, a semiconductor material such as single crystal silicon, or the like.

  A heat storage layer 17 is formed on the upper surface of the substrate 9. The heat storage layer 17 includes a base portion 17a formed on the entire top surface of the substrate 9, and a raised portion 17b extending in a strip shape along the arrangement direction of the plurality of heat generating portions 11 and having a substantially semi-elliptical cross section. Yes. The raised portion 17b acts to favorably press the recording medium to be printed onto the heat generating portion 11.

  In addition, the heat storage layer 17 is formed of, for example, glass having low thermal conductivity, and temporarily accumulates a part of the heat generated in the heat generating part 11 to increase the temperature of the heat generating part 11. The time required is shortened and the thermal response characteristic of the thermal head X is enhanced. The heat storage layer 17 is formed by, for example, applying a predetermined glass paste obtained by mixing a glass powder with an appropriate organic solvent onto the upper surface of the substrate 9 by screen printing or the like, and baking it at a high temperature. Is done.

  As shown in FIG. 2, an electrical resistance layer 19 is provided on the upper surface of the heat storage layer 17. The electrical resistance layer 19 is interposed between the heat storage layer 17 and the electrode wiring 13 and an IC control wiring 21 described later. As shown in FIG. 1, the electrode wiring 13 and the IC control wiring 21 are seen in a plan view. And an area (hereinafter referred to as an intervening area) and a plurality of areas (hereinafter referred to as 56 exposed areas) exposed from between the electrode wirings 13. In FIG. 1, the intervening region of the electric resistance layer 19 is hidden by the electrode wiring 13 and the IC control wiring 21. Each exposed region of the electrical resistance layer 19 forms the heat generating portion 11 described above. The plurality of exposed regions (heat generating portions 11) are arranged in a row on the raised portions 17b of the heat storage layer 17, as shown in FIGS. The plurality of heat generating portions 11 are illustrated in a simplified manner in FIG. 1 for convenience of explanation, but are arranged at a density of, for example, 600 dpi (dot per inch).

  The electrical resistance layer 19 is made of a material having a relatively high electrical resistance, such as TaN, TaSiO, TaSiNO, TiSiO, TiSiCO, or NbSiO. Therefore, when a current is supplied to the heat generating portion 11 through the electrode wiring 13, the heat generating portion 11 generates heat due to Joule heat generation.

  As shown in FIGS. 1 and 2, the electrode wiring 13 and the IC control wiring 21 are provided on the upper surface of the electric resistance layer 19 (more specifically, the upper surface of the intervening region). The electrode wiring 13 and the IC control wiring 21 are made of a conductive material, and are made of, for example, any one of aluminum, gold, silver, and copper, or an alloy thereof.

  The electrode wiring 13 is for supplying a current to each heat generating portion 11. This electrode wiring 13 is connected to each heat generating portion 11 and is an electrode wiring pad portion 13a disposed on the edge opposite to the edge on the substrate 9 where the heat generating portions 11 are arranged. The PWB 5 is connected to the first connection wiring 29a and the second connection wiring 29b via solder or the like (not shown). Thereby, each heat generating part 11 is configured to be electrically connected to the first connection wiring 29 a and the second connection wiring 29 b of the PWB 5 described later via the electrode wiring 13.

The electrode wiring 13 divides a plurality of heat generating portions 11 into a plurality of groups (seven in the illustrated example) and connects the heat generating portions 11 of each group to a drive IC 15 provided corresponding to each group. . The driving IC 15 is connected to a region between the electrode wiring pad portion 13 a of the electrode wiring 13 and a connection portion between the electrode wiring 13 and the heat generating portion 11. The drive IC 15 is for controlling the energization state of each heat generating portion 11, and a known one having a plurality of switching elements (not shown) inside can be used. The drive IC 15 is energized when each switching element is on, and is de-energized when each switching element is off, so that the energization state of each heat generating portion 11 is controlled.

  As shown in FIG. 1, the IC control wiring 21 has one end portion (left end portion in the illustrated example) disposed in a region where the driving IC 15 is disposed on the substrate 9, and the other end portion (right end portion in the illustrated example). ) Extends in a strip shape so as to be disposed on the edge on the side opposite to the edge on the side where the heat generating portions 11 are arranged on the substrate 9. The IC control wiring 21 has one end connected to the driving IC 15 and the control wiring pad 21a at the other end connected to a third connection wiring 29c of the PWB 5 described later via solder or the like (not shown). Has been. The IC control wiring 21 supplies, for example, a power supply current for operating the driving IC 15 or an electric signal for operating the driving IC 15 so as to control the on / off state of the switching element in the driving IC 15. It is for doing.

  The electrical resistance layer 19, the electrode wiring 13 and the IC control wiring 21 are formed by sequentially laminating the material layers constituting each of them on the heat storage layer 17 by a conventionally well-known thin film forming technique such as a sputtering method, for example. It is formed by processing the laminated body into a predetermined pattern using a conventionally known photoetching or the like.

  As shown in FIGS. 1 to 3, the PWB 5 extends along the arrangement direction of the plurality of heat generating portions 11 of the head base 3 and is connected to the electrode wiring 13 and the IC control wiring 21 of the head base 3 as described above. Has been. The PWB 5 includes a first printed wiring layer 25 and a second printed wiring layer 27 that are stacked via the electrical insulating layer 23, and a plurality of connection wirings 29 that are arranged along the arrangement direction of the plurality of heat generating portions 11. is doing. FIG. 3 is a rear view of the PWB 5.

  The electrical insulating layer 23 extends in a strip shape over substantially the entire area of the substrate 9 in the arrangement direction of the heat generating portions 11 along the arrangement direction of the heat generating portions 11. The electrical insulating layer 23 is made of an electrically insulating resin and is interposed between the first printed wiring layer 25 and the second printed wiring layer 27 to electrically insulate them. The electrical insulating layer 23 can be formed of, for example, a film made of a polyimide resin having flexibility or a hard glass epoxy resin.

  Further, as shown in FIG. 2, a protective layer 31 that covers the first printed wiring layer 25 and the second printed wiring layer 27 is formed on the upper and lower surfaces of the electrical insulating layer 23. The protective layer 31 can be formed of, for example, an electrically insulating resin made of polyimide resin, epoxy resin, or the like. In FIG. 1 and FIG. 3, the protective layer 31 is not shown for convenience of explanation.

  As shown in FIGS. 1 and 2, the first printed wiring layer 25 is formed on the upper surface of the electrical insulating layer 23, and the first layer low potential wiring conductor 33, the first layer high potential wiring conductor 35, and the IC control. A wiring conductor 37 is provided.

  The first layer low potential wiring conductor 33 extends along the arrangement direction of the heat generating portions 11. More specifically, the first-layer low-potential wiring conductor 33 includes a first region 33a extending in a band shape from the central portion of the electrical insulating layer 23 toward one end (the upper end in FIG. 1), and the other A second region 33b extending in a strip shape toward the end (the lower end in FIG. 1) and a third region disposed in the center of the electrical insulating layer 23 and connecting the first region 33a and the second region 33b. And a region 33c. The first-layer low-potential wiring conductor 33 has a low-potential connection region 33d connected to the connector 7 described later.

The first layer high potential wiring conductor 35 is formed so as to surround the first layer low potential wiring conductor 33. More specifically, the first-layer high-potential wiring conductor 35 is disposed on both sides of the first-layer low-potential wiring conductor 33 in the direction orthogonal to the arrangement direction of the heat generating portions 11 and extends along the arrangement direction of the heat generating portions 11. The first connection region 35a and the second connection region 35b are provided, and one end portions and the other end portions of the first connection region 35a and the second connection region 35b are connected by the end wiring conductor 35c. The first-layer high-potential wiring conductor 35 has a high-potential connection region 35d formed in the first connection region 35a and connected to the connector 7 described later.

  The IC control wiring conductor 37 extends in an L shape between the first layer low potential wiring conductor 33 and the first layer high potential wiring conductor 35 and extends in a direction orthogonal to the arrangement direction of the heat generating portions 11. The lead portion 37a and the control wiring connecting portion 37b extending in the arrangement direction of the heat generating portions 11 are provided. The lead portion 37a has a signal connection region 37c connected to the connector 7 described later.

  As shown in FIGS. 2 and 3, the second printed wiring layer 27 is formed on the lower surface of the electrical insulating layer 23, and includes a plurality (five in the illustrated example) of second layer low potential wiring conductors 39, and A two-layer high potential wiring conductor 41 is provided.

  The second layer low potential wiring conductors 39 are arranged apart from each other along the arrangement direction of the heat generating portions 11. The plurality of second-layer low-potential wiring conductors 39 are arranged at positions corresponding to the first-layer low-potential wiring conductors 33, and one first connector is formed by the plurality of conductive connectors 43 penetrating the electrical insulating layer 23. The layer low potential wiring conductor 33 is connected in common. Note that the conductive connection body 43 penetrating the electrical insulating layer 23 is formed of, for example, a metal material such as copper, and the formation position is indicated by “■” in FIGS. 1 and 3.

  The second layer high potential wiring conductor 41 is adjacent to the main wiring portion 41a extending along the arrangement direction of the heat generating portions 11 at a position corresponding to the first connection region 35a of the first layer high potential wiring conductor 35. Corresponding to the four sub wiring portions 41b extending along the direction orthogonal to the arrangement direction of the heat generating portions 11 and the end wiring conductor 35c of the first layer high potential wiring conductor 35 between the layer low potential wiring conductors 39. At the position, there are two end wiring portions 41c extending along a direction orthogonal to the arrangement direction of the heat generating portions.

  The main wiring portion 41 a is connected to the first connection region 35 a of the first-layer high-potential wiring conductor 35 by a plurality of conductive connection bodies 43 that penetrate the electrical insulating layer 23.

  The sub-wiring part 41 b has one end connected to the main wiring part 41 a and the other end connected to the second connection region 35 b of the first-layer high-potential wiring conductor 35 through the conductive connection body 43 that penetrates the electrical insulating layer 23. It is connected. The four sub wiring portions 41b have substantially the same width.

  The end wiring portion 41 c is connected to the end wiring conductor 35 c of the first-layer high-potential wiring conductor 35 by a plurality of conductive connectors 43 that penetrate the electrical insulating layer 23.

  As shown in FIGS. 1 and 3, the plurality of connection wirings 29 are formed on the lower surface of the electrical insulating layer 23, and the edge portion (one side) of the PWB 5 extending along the arrangement direction of the heat generating portions 11 (on the one side). A plurality of first connection wirings 29a, a plurality of second connection wirings 29b, and a plurality of third connection wirings 29c.

  As shown in FIG. 3, the first connection wiring 29 a extends in a band shape in a direction perpendicular to the arrangement direction of the heat generating portions 11, and one end thereof is connected to the first connection wiring 43 a through the conductive connection body 43 penetrating the electrical insulating layer 23. The first layer high potential wiring conductor 35 is connected to the second connection region 35 b. The other end of the first connection wiring 29a is connected to an electrode wiring pad portion 13a of the electrode wiring 13 provided on the head base 3 via solder or the like (not shown).

  The second connection wiring 29 b extends in a band shape in a direction orthogonal to the arrangement direction of the heat generating portions 11, and one end is connected to the second layer low potential wiring conductor 39. The other end of the second connection wiring 29b is connected to the electrode wiring pad portion 13a of the electrode wiring 13 provided on the head base 3 via solder or the like (not shown).

  In the present embodiment, by connecting the first connection wiring 29a and the second connection wiring 29b to the electrode wiring 13 provided on the head base 3 in this way, the plurality of heat generating portions 11 are connected via the first connection wiring 29a. The first layer high potential wiring conductor 35 is electrically connected in common to the second connection region 35b, and the plurality of heat generating portions 11 are connected to the second layer low potential wiring conductor 39 via the second connection wiring 29b. They are electrically connected in common.

  The third connection wiring 29 c extends in a band shape in a direction orthogonal to the arrangement direction of the heat generating portions 11, and one end of the third connection wiring 29 c is connected to the control wiring of the IC control wiring conductor 37 via the conductive connection body 43 penetrating the electrical insulating layer 23. It is connected to the connection part 37b. The other end of the third connection wiring 29c is connected to the control wiring pad portion 21a of the IC control wiring 21 provided on the head base 3 via solder or the like (not shown).

  The first layer low potential wiring conductor 33, the first layer high potential wiring conductor 35 and the IC control wiring conductor 37 constituting the first printed wiring layer 25, and the second layer low potential wiring conductor 39 constituting the second printed wiring layer 27. The second-layer high-potential wiring conductor 41 and the connection wiring 29 are made of a conductive material. For example, a metal foil such as a copper foil, a conductive thin film formed by a thin film forming technique, or a thick film. It can be formed by a conductive thick film formed by a printing technique. Moreover, the wiring conductor and connection wiring formed of metal foil or a conductive thin film can be formed in a predetermined pattern by, for example, partially etching these by photoetching or the like.

  The connector 7 is for connecting the first layer low potential wiring conductor 33, the first layer high potential wiring conductor 35 and the IC control wiring conductor 37 to an external power supply device and control device (not shown). The low potential connection region 33 d of the potential wiring conductor 33, the high potential connection region 35 d of the first layer high potential wiring conductor 35, and the signal connection region 37 c of the IC control wiring conductor 37 are connected. In FIG. 1 and FIG. 2, for convenience of explanation, a region where the connector 7 is arranged is indicated by a broken line.

  When the connector 7 is electrically connected to an external power supply device and control device (not shown), the first-layer low-potential wiring conductor 33 is negative of the power supply device held at the ground potential (for example, 0 V to 1 V). The first layer high potential wiring conductor 35 is electrically connected to the side terminal, and is electrically connected to the plus side terminal of the power supply device held at a positive potential (for example, 20V to 24V). As a result, when the switching element of the driving IC 15 is in the ON state, a current is supplied to the heat generating part 11 and the heat generating part 11 generates heat.

  Similarly, when the connector 7 is electrically connected to an external power supply device and control device (not shown), the power supply current for operating the drive IC 15 and the ON / OFF of each switching element in the drive IC 15 are also shown. An electric signal for operating the drive IC 15 so as to control the OFF state is supplied via the IC control wiring conductor 37. By operating the drive IC 15 so as to control the on / off state of each switching element in the drive IC 15 by this electric signal, each heat generating portion 11 can be selectively heated.

A reinforcing plate 45 made of a resin such as polyimide resin or glass epoxy resin is provided between the PWB 5 and the radiator 1. The reinforcing plate 45 acts to reinforce the PWB 5 by being bonded to the lower surface of the PWB 5 with a double-sided tape, an adhesive, or the like (not shown). The reinforcing plate 45 is bonded to the upper surface of the radiator 1 with a double-sided tape, an adhesive, or the like (not shown), so that the PWB 5 is fixed on the radiator 1.

  When a thermal printer is configured by applying the thermal head X, the thermal head X is arranged so that the arrangement direction of the plurality of heating portions 11 is orthogonal to the conveyance direction of the recording medium to be printed. Then, while the recording medium is pressed onto the heat generating portion 11 of the thermal head X by a platen roller or the like, the heat generating portion 11 is selectively heated while conveying the recording medium. In this way, a predetermined print is performed on the recording medium. Note that the direction perpendicular to the conveyance direction of the recording medium is the main scanning direction.

  According to the thermal head X of the present embodiment, a plurality of second layer low potentials arranged along the arrangement direction of the heat generating portions 11 on the first layer low potential wiring conductors 33 extending along the arrangement direction of the heat generating portions 11. The wiring conductor 39 is connected in common by a plurality of conductive connectors 43. Thus, the current flowing through the first layer low potential wiring conductor 33 can also flow through the second layer low potential wiring conductor 39, and thus flows through the first layer low potential wiring conductor 33 and the second layer low potential wiring conductor 39. The electric resistance against current can be reduced. Therefore, the voltage drop in the first-layer low-potential wiring conductor 33 can be reduced, and variations in the magnitude of the current supplied to each heat generating portion 11 can be suppressed. As a result, the density unevenness of the print by the thermal head X can be reduced.

  In addition, according to the thermal head X of the present embodiment, a plurality of second layer low potential wiring conductors 39 are laminated on the one first layer low potential wiring conductor 33 via the electrical insulating layer 23. Therefore, deformation due to internal stress is unlikely to occur in the PWB 5 and it is possible to suppress the PWB 5 from being peeled off from the connection portion with the head base 3. That is, one large second layer low potential wiring conductor formed by coupling a plurality of second layer low potential wiring conductors 39 to each other is connected to one first layer low potential wiring conductor 33 via the electrical insulating layer 23. In this case, the internal stress is generated in the PWB 5 due to the difference in thermal expansion coefficient between the one large second layer low potential wiring conductor, the electrical insulating layer 23 and the first layer low potential wiring conductor 33. Occurs and the PWB 5 is easily deformed. On the other hand, according to the thermal head X of the present embodiment, a plurality of small second layer low potential wiring conductors 39 are laminated on the one first layer low potential wiring conductor 33 via the electrical insulating layer 23. Therefore, even if internal stress is generated due to the difference in thermal expansion coefficient between the first layer low-potential wiring conductor 33 and the electrical insulation layer 23 and the electrical insulation layer 23 is bent, this deflection is applied to the adjacent second layer. It is possible to escape into the gap between the layer low potential wiring conductors 39. Therefore, the internal stress of the PWB 5 can be reduced, and the deformation of the PWB 5 due to the internal stress is less likely to occur, so that the PWB 5 can be prevented from peeling from the connection portion with the head base 3.

  Further, in the thermal head X of the present embodiment, the first layer high potential wiring conductor 35 is formed so as to surround the first layer low potential wiring conductor 33. Therefore, the high potential connection region 35d to which the connector 7 is connected. The voltage drop tends to be large in the second connection region 35b located away from the second connection region 35b. On the other hand, according to the thermal head X of the present embodiment, the main wiring portion 41a of the second layer high potential wiring conductor 41 is placed by the conductive connector 43 in the first connection region 35a of the first layer high potential wiring conductor 35. One end of the sub wiring portion 41b is connected to the main wiring portion 41a, and the other end of the sub wiring portion 41b is connected to the second connection region 35b of the first-layer high-potential wiring conductor 35 through the conductive connection body 43. Connected. Therefore, the current flowing from the high potential connection region 35d of the first layer high potential wiring conductor 35 passes through the sub wiring portion 41b of the second layer high potential wiring conductor 41 at a short distance, and thus the first layer high potential wiring conductor 35. Can flow into the second connection region 35b. Therefore, the voltage drop in the second connection region 35b of the first-layer high-potential wiring conductor 35 can be reduced, and variation in the magnitude of the current supplied to each heat generating portion 11 can be suppressed. . As a result, the density unevenness of the print by the thermal head X can be reduced.

As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible unless it deviates from the meaning.

  In the thermal head X of the above embodiment, the connector 7 is connected to the low potential connection region 33d of the first layer low potential wiring conductor 33 and the high potential connection region 35d of the first layer high potential wiring conductor 35. It is not limited to this. For example, in addition to the low potential connection region 33d of the first layer low potential wiring conductor 33, the connector 7 may be connected to the region of the second layer low potential wiring conductor 39 corresponding to the low potential connection region 33d. In addition to the high potential connection region 35d of the first layer high potential wiring conductor 35, the connector 7 may be connected to the region of the second layer high potential wiring conductor 41 corresponding to the high potential connection region 35d.

  In the thermal head X of the above embodiment, the low potential connection region 33 d of the first layer low potential wiring conductor 33, the high potential connection region 35 d of the first layer high potential wiring conductor 35, and the signal connection of the IC control wiring conductor 37. A connector is connected to the region 37c, and the PWB 5 is electrically connected to an external power supply device and a control device via the connector 7, but current can be supplied to the heat generating unit 11 via the PWB 5. As long as it is not limited to this. For example, the connector 7 is not provided in the thermal head C of the above embodiment, and the external power supply device and the control device are configured by using the low potential connection region 33d, the high potential connection region 35d, and the signal connection region 37c of the PWB 5 as card edge type connection terminals. You may make it electrically connect to.

  In the PWB 5 of the thermal head X of the above embodiment, the second layer low potential wiring conductor 39 is divided into five and connected to one first layer low potential wiring conductor 33 as shown in FIG. However, the number of divisions of the second layer low-potential wiring conductor 39 is not limited to this, and it may be divided into an arbitrary number and connected to the first layer low-potential wiring conductor 33.

  Further, in the PWB 5 of the thermal head X of the above embodiment, the number of the sub wiring portions 41b of the second-layer high-potential wiring conductor 41 is four as shown in FIG. An arbitrary number may be used according to the number of divisions of the second layer low potential wiring conductor 39.

  Further, in the PWB 5 of the thermal head X of the above embodiment, the four sub wiring portions 41b of the second-layer high-potential wiring conductor 41 have substantially the same width. The width of the wiring part 41b may be arbitrarily set. For example, as shown in FIG. 4, the width of the sub-wiring portion 41 b may be wider as the sub-wiring portion 41 b arranged at a position away from the high-potential connection region 35 d of the first layer high-potential wiring conductor 35. Good. By doing so, a larger amount of current is more likely to flow in a position away from the high potential connection region 35d of the second connection region 35b of the first layer high potential wiring conductor 35, so that a voltage drop in the second connection region 35b is further reduced. Can be reduced.

  Further, in the PWB 5 of the thermal head X of the above embodiment, as shown in FIG. 5, the arrangement density of the sub wiring portions 41b increases as the distance from the high potential connection region 35d of the second layer high potential wiring conductor 41 increases. You may comprise so that it may become. This also facilitates a large amount of current to flow in a position away from the high potential connection region 35d of the second connection region 35b of the first layer high potential wiring conductor 35. Therefore, the voltage drop in the second connection region 35b is reduced. It can be further reduced.

X Thermal Head 1 Heat Dissipator 3 Head Base 5 PWB (Multilayer Printed Wiring Board)
7 Connector 9 Substrate 11 Heating part 23 Electrical insulation layer 25 First printed wiring layer 27 Second printed wiring layer 29 Connection wiring 29a First connection wiring 29b Second connection wiring 29c Third connection wiring 33 First layer low potential wiring conductor 33d Low potential connection area 35 First layer high potential wiring conductor 35a First connection area 35b Second connection area 35c End wiring conductor 35d High potential connection area 39 Second layer low potential wiring conductor 41 Second high potential wiring conductor 41a Main wiring Part 41b Sub-wiring part 41c End wiring part 43 Conductive connector

Claims (4)

A head base having a substrate and a plurality of heat generating portions arranged on the substrate;
Extending along the arrangement direction of the heat generating parts, comprising a multilayer printed wiring board for supplying current to the heat generating parts,
The multilayer printed wiring board has a first printed wiring layer and a second printed wiring layer laminated via an electrical insulating layer, and is arranged along one edge extending along the arrangement direction of the heat generating parts. A plurality of connection wirings electrically connected to the heat generating portion;
The first printed wiring layer includes a first layer low-potential wiring conductor extending along the arrangement direction of the heat generating portions, and a first layer high-potential wiring conductor formed so as to surround the first layer low-potential wiring conductor. Have
The first layer low potential wiring conductor has a low potential connection region for electrically connecting the first layer low potential wiring conductor to an external power supply device,
The first-layer high-potential wiring conductor is disposed on both sides of the first-layer low-potential wiring conductor in a direction orthogonal to the arrangement direction of the heat generating parts, and extends along the arrangement direction of the heat generating parts. And a second connection region, and a high potential connection region formed in the first connection region for electrically connecting the first layer high potential wiring conductor to an external power supply device,
The second printed wiring layer has a plurality of second layer low potential wiring conductors arranged apart from each other along the arrangement direction of the heat generating parts,
The plurality of connection wires include a plurality of first connection wires connected to the second connection region of the first layer high potential wiring conductor and a plurality of second connections connected to the second layer low potential wiring conductor. A plurality of heat generating portions electrically connected in common to the second connection region of the first-layer high-potential wiring conductor via the first connection wiring; and The plurality of heat generating portions are electrically connected in common to the plurality of second-layer low-potential wiring conductors via two connection wires;
The thermal head, wherein the plurality of second layer low potential wiring conductors are connected in common to one first layer low potential wiring conductor by a plurality of conductive connectors penetrating the electrical insulating layer. . The second printed wiring layer includes a main wiring portion extending along the arrangement direction of the heat generating portions at a position corresponding to the first connection region of the first layer high potential wiring conductor, and the adjacent second layer low A second-layer high-potential wiring conductor having a sub-wiring portion extending along a direction orthogonal to the arrangement direction of the heat generating portions between the potential wiring conductors;
The main wiring portion is connected to the first connection region of the first-layer high-potential wiring conductor by a plurality of conductive connectors that penetrate the electrical insulating layer,
One end of the sub-wiring portion is connected to the main wiring portion, and the other end is connected to the second connection region of the first-layer high-potential wiring conductor via a conductive connector that penetrates the electrical insulating layer. The thermal head according to claim 1, wherein the thermal head is provided.   3. The thermal head according to claim 2, wherein the sub-wiring portion is wider as the sub-wiring portion is arranged at a position away from the high-potential connection region. 4. The thermal head according to claim 2, wherein an arrangement density of the sub-wiring portions increases as a distance from the high potential connection region increases. 5.

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