JP2012006341A - Thermal head and thermal printer having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal head capable of suppressing fogging in printing due to a curvature of a heating section row while preventing increase of manufacturing cost, and to provide a thermal printer having the same.SOLUTION: The thermal head X includes a substrate 7 and the heating section row 9A consisting of a plurality of heating sections 9 arranged on the substrate 7. The heating section row 9A is curved so as to be convex in a direction perpendicular to a main-scanning direction in plan view. The plurality of heating sections 9 are arranged along a curve line which is curved so as to be convex at the side where the heating sections 9 are arranged as viewed from the substrate 7.

Description

  The present invention relates to a thermal head and a thermal printer including the same.

  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 includes a substrate (ceramic substrate) and a heat generating portion array (heat generating element array) including a plurality of heat generating portions (heat generating elements) arranged on the substrate. The substrate of this thermal head is formed by dividing a ceramic substrate body into a plurality of sections, and the divided substrate may be curved in a bow shape. Therefore, in the thermal head described in Patent Document 1, the heating part rows formed in the respective sections are divided at the stage of the ceramic substrate body before division so that the heating part rows are not bent as the substrate is bent. The substrate is bent in a direction opposite to the subsequent substrate bending direction. By doing so, since the heat generating portion row on the substrate after the division becomes linear, the pressing force of the platen against the heat generating portion row on the substrate becomes uniform, and blurring of printing is suppressed.

Japanese Patent Laid-Open No. 11-20215

  In the thermal head described in Patent Document 1, the heat generating portion row is curved using a photolithography technique. Therefore, when the amount of bending of the substrate after division changes, it is necessary to change the photomask accordingly. Since this photomask is expensive, there is a problem in that the manufacturing cost increases.

  The present invention has been made to solve the above-described problem, and a thermal head capable of suppressing blurring of a print caused by the curvature of a heat generating portion array while suppressing an increase in manufacturing cost, and a thermal head including the same. An object is to provide a printer.

  A thermal head according to an embodiment of the present invention includes a substrate and a heat generating portion row including a plurality of heat generating portions arranged on the substrate, and the heat generating portion row is orthogonal to the main scanning direction in plan view. And the plurality of heat generating portions are arranged along a curve curved in a convex shape on the side where the heat generating portions are arranged as viewed from the substrate. It is characterized by.

  In the thermal head according to an embodiment of the present invention, the substrate may have a rectangular shape in plan view, and may be formed such that the longitudinal direction of the substrate is along the main scanning direction. Or the said board | substrate may be formed so that it may extend in strip | belt shape along the curve curved convexly in the direction orthogonal to the main scanning direction by planar view.

  A printer according to an embodiment of the present invention includes the thermal head according to the above-described embodiment of the present invention, and a platen roller that extends in the main scanning direction and presses a recording medium onto the plurality of heat generating units. The platen roller is characterized in that both end portions are rotatably supported.

  ADVANTAGE OF THE INVENTION According to this invention, the thermal head which can suppress the blurring of the printing resulting from the curvature of a heat generating part row | line | column, suppressing a manufacturing cost increase, and a thermal printer provided with the same can be provided.

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. FIG. 3 is a sectional view taken along line III-III of the thermal head of FIG. 1. FIG. 4 is a cross-sectional view taken along line IV-IV of the thermal head in FIG. 1. FIG. 2 is a plan view of a head substrate in the thermal head of FIG. 1. FIG. 6 is a plan view of the head substrate of FIG. 5 with the first protective layer, the second protective layer, the drive IC, and the covering member omitted. It is a top view which shows the state which connected FPC to the head base | substrate which abbreviate | omitted illustration of the 1st protective layer, the 2nd protective layer, and the coating | coated member. It is a figure which shows schematic structure of one Embodiment of the thermal printer of this invention. It is a top view which shows typically the positional relationship of the platen roller at the time of stationary, and a heat generating part row | line | column. FIG. 5 is a cross-sectional view illustrating a state where a platen roller is pressed onto a heat generating portion of the thermal head in FIG. 4. It is a top view which shows typically the positional relationship of the platen roller at the time of rotation, and a heat generating part row | line | column.

  Hereinafter, an embodiment of a thermal head of the present invention will be described with reference to the drawings. As shown in FIGS. 1 to 4, the thermal head X of the present embodiment includes a radiator 1, a head substrate 3 disposed on the radiator 1, and a flexible printed wiring board 5 ( Hereinafter referred to as FPC5).

  The radiator 1 includes a base plate portion 1a that is rectangular in plan view, and a protruding portion 1b that extends along one long side of the base plate portion 1a (the long side on the right side in FIG. 1). As shown in FIG. 2, the head substrate 3 is bonded to the upper surface of the base plate 1a by a double-sided tape, an adhesive, or the like (not shown). As shown in FIG. 4, the upper surface of the base plate portion 1a has a curved surface shape in which the central portion in the longitudinal direction of the base plate portion 1a is convex. The FPC 5 is bonded onto the protruding portion 1b by a double-sided tape, an adhesive, or the like (not shown). The radiator 1 is made of, for example, a metal material such as copper or aluminum, and dissipates a part of heat generated in the heat generating portion 9 of the head base 3 that does not contribute to printing as will be described later. It has a function to do.

  As shown in FIGS. 1 to 5, the head base 3 includes a heating unit row 9 </ b> A including a rectangular substrate 7 in plan view and a plurality (24 in the illustrated example) of heating units 9 arranged on the substrate 7. And a plurality (three in the illustrated example) of driving ICs 11 arranged side by side on the substrate 7 along the longitudinal direction of the substrate 7. FIG. 5 is a plan view of the head base 3. FIG. 6 is a plan view of the head base 3 in which the first protective layer 25, the second protective layer 27, the drive IC 11 and the covering member 29 which will be described later are omitted.

  The substrate 7 is made of an electrically insulating material such as alumina ceramic, a semiconductor material such as single crystal silicon, or the like. The board | substrate 7 is adhere | attached on the upper surface of the baseplate part 1a which has the curved-surface shape from which the center part of a longitudinal direction becomes convex as mentioned above. As a result, the substrate 7 is curved, and the upper surface of the substrate 7 has a curved shape in which the central portion in the longitudinal direction of the substrate 7 is convex like the upper surface of the base plate portion 1a.

  A heat storage layer 13 is formed on the upper surface of the substrate 7. The heat storage layer 13 includes a base portion 13a formed on the entire upper surface of the substrate 7, and a raised portion 13b extending in a strip shape along the heat generating portion row 9A and having a substantially semi-elliptical cross section. The raised portions 13b act so as to favorably press the recording medium to be printed against a first protective layer 25 described later formed on the heat generating portion 9.

  In addition, the heat storage layer 13 is made of, for example, glass having low thermal conductivity, and temporarily accumulates part of the heat generated in the heat generating part 9 to increase the temperature of the heat generating part 9. The time required is shortened and the thermal response characteristic of the thermal head X is enhanced. The heat storage layer 13 is formed, for example, by applying a predetermined glass paste obtained by mixing a glass powder with an appropriate organic solvent onto the upper surface of the substrate 7 by screen printing or the like, and baking it at a high temperature. Is done.

  As shown in FIGS. 2 and 3, an electrical resistance layer 15 is provided on the upper surface of the heat storage layer 13. The electrical resistance layer 15 is interposed between the heat storage layer 13 and a later-described common electrode wiring 17, individual electrode wiring 19, ground electrode wiring 21, and IC control wiring 23. As shown in FIG. These individual electrode wiring 19, common electrode wiring 17, ground electrode wiring 21 and IC control wiring 23 are exposed from the same shape area (hereinafter referred to as an intervening area) and between the individual electrode wiring 19 and the common electrode wiring 17. A plurality of regions (hereinafter referred to as exposed regions). In FIG. 6, the intervening region of the electric resistance layer 15 is hidden by the common electrode wiring 17, the individual electrode wiring 19, the ground electrode wiring 21, and the IC control wiring 23.

  Each exposed region of the electrical resistance layer 15 forms the heat generating portion 9 described above. Then, as shown in FIGS. 2 and 6, the plurality of exposed regions (heat generating portions 9) are arranged in a row on the raised portions 13 b of the heat storage layer 13. More specifically, a heating unit row 9A composed of a plurality of heating units 9 is viewed in a plan view as shown in FIG. 6, and the central portion of the heating unit row 9A is longer than one of the long sides of the substrate 7 (see FIG. 6). In the illustrated example, it is curved so as to approach the left long side). By doing so, the heating element row 9A is curved so as to be convex in a direction orthogonal to the main scanning direction of the thermal head X in plan view. The main scanning direction of the thermal head X is a direction orthogonal to the conveyance direction of the recording medium in a thermal printer to which the thermal head is applied.

  Further, the plurality of heat generating portions 9 constituting the heat generating portion row 9A has a curved surface shape in which the upper surface of the substrate 7 is convex in the central portion in the longitudinal direction of the substrate 7 as described above. As shown in FIG. 4, the substrate 7 is arranged along a curved curve that is convexly curved on the upper surface side (the side on which the heat generating portions 9 are arranged as viewed from the substrate 7). The upper surface of the substrate 7 has, for example, a central portion in the longitudinal direction that protrudes 30 to 80 μm from both ends.

  For convenience of explanation, the plurality of heat generating portions 9 are illustrated in a simplified manner in FIGS. 1, 5, and 6, but are arranged at a density of, for example, 600 dpi (dot per inch).

  The electric resistance layer 15 is made of a material having a relatively high electric resistance, such as TaN, TaSiO, TaSiNO, TiSiO, TiSiCO, or NbSiO. Therefore, when a voltage is applied between the common electrode wiring 17 and the individual electrode wiring 19 which will be described later and a current is supplied to the heat generating portion 9, the heat generating portion 9 generates heat due to Joule heat generation.

As shown in FIGS. 1 to 7, the common electrode wiring 17, the individual electrode wiring 19, the ground electrode wiring 21, and the IC control wiring are formed on the upper surface of the electric resistance layer 15 (more specifically, the upper surface of the intervening region). 23 is provided. The common electrode wiring 17, the individual electrode wiring 19, the ground electrode wiring 21, and the IC control wiring 23 are made of a conductive material. For example, any one of aluminum, gold, silver, and copper is used. It is formed of a metal or an alloy thereof. FIG. 7 is a plan view showing a state in which the FPC 5 is connected to the head base 3 in which the first protective layer 25, the second protective layer 27, and the covering member 29 described later are omitted.

  As shown in FIG. 6, the common electrode wiring 17 includes a main wiring portion 17 a extending along one long side (the left long side in FIG. 6) of the substrate 7, and one and other short sides (see FIG. 6). 5, two sub-wiring portions 17 b extending along each of the upper and lower short sides and having one end portion (left end portion in FIG. 6) connected to the main wiring portion 17 a, and the main wiring portion 17 a And a plurality (24 in the illustrated example) of lead portions 17c extending toward the respective heat generating portions 9. As shown in FIG. 7, the other end portion (right end portion in FIG. 7) of the sub wiring portion 17b is connected to the FPC 5 and the tip end portion (right end portion in FIG. 7) of the lead portion 17c. Is connected to the heat generating part 9. Thereby, the FPC 5 and the heat generating part 9 are electrically connected.

  As shown in FIGS. 2, 6, and 7, the individual electrode wiring 19 extends between each heat generating portion 9 and the drive IC 11, and connects between them. More specifically, the individual electrode wiring 19 divides a plurality of heat generating portions 9 into a plurality of groups (three in the illustrated example), and the heat generating portions 9 of each group are connected to a drive IC 11 provided corresponding to each group. Electrically connected.

  As shown in FIG. 6, the ground electrode wiring 21 extends in a strip shape along the other long side (the long side on the right side in the illustrated example) of the substrate 7. On the ground electrode wiring 21, as shown in FIGS. 3 and 7, the FPC 5 and the drive IC 11 are connected. More specifically, as shown in FIG. 7, the FPC 5 is connected to an end region 21E located at one end and the other end of the ground electrode wiring 21, and is also connected to a ground located between adjacent drive ICs 11. The electrode wiring 21 is connected to the first intermediate region 21M. The driving IC 11 is connected to the second intermediate region 21N between the end region 21E of the ground electrode wiring 21 and the first intermediate region 21M, and the third intermediate region 21L between the adjacent first intermediate regions 21M. It is connected to the. Thereby, the drive IC 11 and the FPC 5 are electrically connected.

  As shown in FIG. 7, the drive IC 11 is disposed corresponding to each group of the plurality of heat generating portions 9, and includes one end portion (right end portion in FIG. 7) of the individual electrode wiring 19, the ground electrode wiring 21, and the like. It is connected to the. This drive IC 11 is for controlling the energization state of each heat generating part 9, and has a plurality of switching elements inside, as will be described later, and is energized when each switching element is in the ON state. A known element that is in a non-energized state when each switching element is in an off state can be used. As shown in FIG. 2, each drive IC 11 is connected to an internal switching element (not shown), and one (left side in the illustrated example) connection terminal 11a (hereinafter referred to as the first connection terminal 11a) is an individual electrode wiring. The other connection terminal 11b (right side in the illustrated example) (hereinafter referred to as the second connection terminal 11b) connected to the switching element is connected to the ground electrode wiring 21. Thereby, when each switching element of the driving IC 11 is in the ON state, the individual electrode wiring 19 and the ground electrode wiring 21 connected to each switching element are electrically connected. As a result, the ground electrode wiring 21 is electrically connected in common to the plurality of heating portions 9 connected to the individual electrode wiring 19.

  Although not shown, a plurality of first connection terminals 11 a connected to the individual electrode wirings 19 and a plurality of second connection terminals 11 b connected to the ground electrode wirings 21 are provided corresponding to the individual electrode wirings 19. ing. The plurality of first connection terminals 11 a are individually connected to each individual electrode wiring 19. The plurality of second connection terminals 11 b are connected in common to the ground electrode wiring 21.

The IC control wiring 23 is for controlling the driving IC 11 and includes an IC power supply wiring 23a and an IC signal wiring 23b as shown in FIGS. IC power supply wiring 23
a has an end power wiring portion 23aE disposed in the vicinity of the long side on the right side of the substrate 7 at both ends in the longitudinal direction of the substrate 7, and an intermediate power wiring portion 23aM disposed between the adjacent driving ICs 11. is doing.

  As shown in FIG. 7, the end power supply wiring portion 23 a </ i> E has one end portion arranged in the arrangement region of the drive IC 11, so as to wrap around the ground electrode wiring 21, and the other end portion being the long side on the right side of the substrate 7 It is arranged in the vicinity. The end power wiring portion 23aE has one end connected to the drive IC 11 and the other end connected to the FPC 5.

  As shown in FIG. 7, the intermediate power supply wiring portion 23 a </ i> M extends along the ground electrode wiring 21, one end portion is arranged in one arrangement region of the adjacent drive IC 11, and the other end portion is the other of the adjacent drive IC 11. Arranged in the arrangement area. The intermediate power supply wiring portion 23aM has one end connected to one of the adjacent drive ICs 11, the other end connected to the other of the adjacent drive ICs 11, and the intermediate connected to the FPC 5 (see FIG. 3).

  The end power supply wiring portion 23aE and the intermediate power supply wiring portion 23aM are electrically connected inside the drive IC 11 to which both of them are connected. The adjacent intermediate power supply wiring portions 23aM are electrically connected inside the drive IC 11 to which both of them are connected.

  By connecting the IC power supply wiring 23a to each drive IC 11 in this way, the IC power supply wiring 23a electrically connects each drive IC 11 and the FPC 5. As a result, as will be described later, a power supply current is supplied from the FPC 5 to each drive IC 11 via the end power supply wiring portion 23aE and the intermediate power supply wiring portion 23aM.

  As shown in FIGS. 6 and 7, the IC signal wiring 23 b is connected to the end signal wiring portion 23 b E disposed in the vicinity of the long side on the right side of the substrate 7 at both ends in the longitudinal direction of the substrate 7 and the adjacent driving IC 11. And an intermediate signal wiring portion 23bM disposed therebetween.

  As shown in FIG. 7, the end signal wiring portion 23bE has one end portion disposed in the region where the drive IC 11 is disposed and the other end thereof so as to wrap around the ground electrode wiring 21 in the same manner as the end power supply wiring portion 23aE. The part is arranged in the vicinity of the long side on the right side of the substrate 7. The end signal wiring portion 23bE has one end connected to the drive IC 11 and the other end connected to the FPC 5.

  The intermediate signal wiring portion 23bM is arranged in one arrangement region of the adjacent driving IC 11 with one end portion thereof, and wraps around the periphery of the intermediate power supply wiring portion 23aM so that the other end portion is arranged in the other arrangement region of the driving IC 11 adjacent thereto. Has been placed. The intermediate signal wiring portion 23bM has one end connected to one of the adjacent drive ICs 11 and the other end connected to the other of the adjacent drive ICs 11.

  The end signal wiring portion 23bE and the intermediate signal wiring portion 23bM are electrically connected inside the driving IC 11 to which both of them are connected. Further, the adjacent intermediate signal wiring portions 23bM are electrically connected inside the drive IC to which both of them are connected.

  By connecting the IC signal wiring 23b to each driving IC 11 in this way, the IC signal wiring 23b electrically connects each driving IC 11 and the FPC 5. As a result, as described later, the control signal transmitted from the FPC 5 to the drive IC 11 via the end signal wiring portion 23bE is further transmitted to the adjacent drive IC 11 via the intermediate signal wiring portion 23b. .

  The electrical resistance layer 15, the common electrode wiring 17, the individual electrode wiring 19, the ground electrode wiring 21, and the IC control wiring 23 are conventionally well-known, for example, by forming a material layer constituting each on the heat storage layer 13, for example, sputtering. After sequentially laminating by the thin film forming technique, the laminated body is formed by processing into a predetermined pattern using a conventionally known photolithography technique, etching technique or the like. The common electrode wiring 17, the individual electrode wiring 19, the ground electrode wiring 21, and the IC control wiring 23 can be simultaneously formed by the same process.

  As shown in FIGS. 1 to 3, on the heat storage layer 13 formed on the upper surface of the substrate 7, the first protection covering the heat generating portion 9, a part of the common electrode wiring 17 and a part of the individual electrode wiring 19. Layer 25 is formed. In the illustrated example, the first protective layer 25 is provided so as to cover a substantially left half region of the upper surface of the heat storage layer 13. The first protective layer 25 protects the heat generating portion 9, the common electrode wiring 17 and the individual electrode wiring 19 from corrosion due to adhesion of moisture contained in the atmosphere and wear due to contact with the recording medium to be printed. Is for. The first protective layer 25 can be formed of a material such as SiC, SiN, SiO, and SiON, for example. The first protective layer 25 can be formed by using a conventionally well-known thin film forming technique such as a sputtering method or a vapor deposition method, or a thick film forming technique such as a screen printing method. The first protective layer 25 may be formed by laminating a plurality of material layers.

  As shown in FIGS. 1 to 3, the common electrode wiring 17, the individual electrode wiring 19, the IC control wiring 23, and the ground electrode wiring 21 are partially provided on the heat storage layer 13 formed on the upper surface of the substrate 7. A second protective layer 27 to be covered is provided. In the example of illustration, this 2nd protective layer 27 is provided so that the area | region of the substantially right half of the upper surface of the thermal storage layer 13 may be covered partially. The second protective layer 27 is used to oxidize a region covered with the common electrode wiring 17, the individual electrode wiring 19, the ground electrode wiring 21, and the IC control wiring 23 due to contact with the atmosphere, moisture contained in the atmosphere, or the like. It is intended to protect against corrosion due to adhesion. Note that the second protective layer 27 overlaps the end portion of the first protective layer 25 as shown in FIG. 2 in order to ensure the protection of the common electrode wiring 17, the individual electrode wiring 19 and the IC control wiring 23. Is formed. The 2nd protective layer 27 can be formed with resin materials, such as an epoxy resin and a polyimide resin, for example. The second protective layer 27 can be formed using a thick film forming technique such as a screen printing method.

  Note that the second protective layer 27 exposes the end portions of the individual electrode wiring 19 that connects the driving IC 11, the second intermediate region 21 N and the third intermediate region 21 L of the ground electrode wiring 21, and the end portion of the IC control wiring 23. For this purpose, an opening (see reference numeral 27a in FIG. 2) is formed, and these wirings are connected to the driving IC 11 through this opening. In addition, the drive IC 11 is connected to the individual electrode wiring 19, the ground electrode wiring 21, and the IC control wiring 23 to protect the drive IC 11 itself and to protect the connection portion between the drive IC 11 and these wirings. It is sealed by being covered with a covering member 29 made of resin such as resin or silicone resin.

  As shown in FIG. 7, the FPC 5 is connected to the common electrode wiring 17, the ground electrode wiring 21, and the IC control wiring 23 as described above. This FPC 5 is a well-known one in which a plurality of printed wirings are wired inside an insulating resin layer, and each printed wiring is connected to an external power supply device (not shown) via a connector 31 (see FIGS. 1 and 7). And it is electrically connected to a control device or the like.

More specifically, in the FPC 5, each printed wiring formed inside is connected to the end portion of the sub-wiring portion 17b of the common electrode wiring 17 and the end portion of the ground electrode wiring 21 by the conductive bonding material 33 (see FIG. 3). The IC control wirings 23 are connected to the end portions of the IC control wirings 23, respectively. The conductive bonding material 33 is, for example, a solder material,
Alternatively, an anisotropic conductive material (ACF) in which conductive particles are mixed in an electrically insulating resin can be used. When the connector 31 is electrically connected to an external power supply device and control device (not shown), the common electrode wiring 17 is connected to the positive terminal of the power supply device held at a positive potential (for example, 20V to 24V). The individual electrode wirings 19 are connected to the negative terminal of the power supply device held at a ground potential (for example, 0 V to 1 V). For this reason, when the switching element of the drive IC 11 is in the on state, a current is supplied to the heat generating portion 9 and the heat generating portion 9 generates heat.

  When the connector 31 is electrically connected to an external power supply device and control device (not shown), the IC power supply wiring 23a of the IC control wiring 23 is a power supply held at a positive potential, like the common electrode wiring 17. It is designed to be connected to the positive terminal of the device. As a result, a current for operating the drive IC 11 is supplied to the drive IC 11 by the potential difference between the IC power supply wiring 23 a to which the drive IC 11 is connected and the ground electrode wiring 21. Further, the IC signal wiring 23 b of the IC control wiring 23 is connected to a control device that controls the driving IC 11. Thereby, the control signal from the control device is transmitted to the drive IC 11 via the end signal wiring portion 23bE, and the control signal transmitted to the drive IC 11 is further transmitted to the adjacent drive IC via the intermediate signal wiring portion 23bM. Is transmitted. By controlling the on / off state of the switching element in the drive IC 11 by this control signal, the heat generating portion 9 can be selectively heated.

  Next, an embodiment of the thermal printer of the present invention will be described with reference to FIG. FIG. 8 is a schematic configuration diagram of the thermal printer Z of the present embodiment.

  As shown in FIG. 8, the thermal printer Z of the present embodiment includes the thermal head X, the transport mechanism 40, the power supply device 50, and the control device 60 described above. The thermal head X is attached on an installation surface 70a of an installation table 70 provided in a casing (not shown) of the thermal printer Z. The thermal head X is configured so that the longitudinal direction of the substrate 7 is along a direction (main scanning direction) (direction perpendicular to the paper surface of FIG. 8) perpendicular to the conveyance direction S of the recording medium P described later. The heat generating portion row 9A is arranged on the installation table 70 so as to be curved in a convex shape in the transport direction S (direction orthogonal to the main scanning direction) of the recording medium P.

  The transport mechanism 40 is in the direction of arrow S in FIG. 8 in a state in which the recording medium P such as thermal paper or ink film is in contact with the plurality of heat generating portions 9 of the thermal head X (more specifically, through the protective film 25). It has a platen roller 41 and conveying rollers 43, 45, 47, 49. The conveyance speed of the recording medium P of the conveyance mechanism 40 is, for example, 100 to 260 mm / second.

  The platen roller 41 is for pressing the recording medium P onto the heat generating portion 9 of the thermal head X, and is arranged so as to extend along a direction (main scanning direction) orthogonal to the conveyance direction S of the recording medium P. Both ends of the recording medium P are supported so that the recording medium P can be rotated while being pressed onto the heat generating portion 9. The platen roller 41 is configured by covering a cylindrical shaft body 41a made of metal such as stainless steel with an elastic member 41b made of butadiene rubber or the like. The roller diameter of the platen roller 41 is, for example, 12 to 20 mm. The elastic member 41b has a Shore hardness A of 40 to 60 degrees, for example. The diameter of the shaft body 41a is, for example, 5 to 8 mm.

  The conveyance rollers 43, 45, 47, and 49 are for conveying the recording medium P along a predetermined path and supplying the recording medium P between the heat generating portion 9 of the thermal head X and the platen roller 41. . The transport rollers 43, 45, 47 and 49 can be configured in the same manner as the platen roller 41.

  The power supply device 50 is for supplying a current for causing the heat generating portion 9 of the thermal head X to generate heat and a current for operating the drive IC 11 as described above. The control device 60 is for supplying a control signal for controlling the operation of the driving IC 11 to the driving IC 11 in order to selectively generate heat in the heat generating portion 9 of the thermal head X as described above.

  As shown in FIG. 8, the thermal printer Z of the present embodiment selects the heat generating portion 9 of the thermal head X by the power supply device 50 and the control device 60 while transporting the recording medium P onto the thermal head X by the transport mechanism 40. By generating heat automatically, a predetermined printing can be performed on the recording medium P.

  According to the thermal head X of the present embodiment, the heat generating portion row 9A is curved so as to be convex in a direction orthogonal to the main scanning direction (recording medium transport direction) in plan view as shown in FIG. ing. Therefore, when the platen roller 41 pressed on the heat generating portion 9 is stationary, the axis of the platen roller 41 and the heat generating portion row 9A are greatly displaced as shown in FIG. FIG. 9 is a plan view schematically showing the positional relationship between the platen roller 41 and the heat generating portion row 9A when stationary.

  On the other hand, in the thermal head X of the present embodiment, as shown in FIG. 4, the plurality of heat generating portions 9 are convex on the upper surface side of the substrate 7 (the side where the heat generating portions 9 are arranged when viewed from the substrate 7). It is arranged along a curved line. Therefore, as shown in FIG. 10, since the platen roller 41 pressed on the heat generating portion 9 is rotatably supported at both ends thereof, a plurality of heat generating portions 9 arranged along this curved curve. It curves so that. At this time, the platen roller 41 presses the heating portion 9 with a greater force at the center than at both ends in the length direction. Therefore, the conveyance rollers 43 and 45 located downstream of the platen roller 41 in the conveyance direction S of the recording medium P are rotated by a driving motor (not shown), whereby the recording medium P is pulled in the conveyance direction. When the platen roller 41 rotates, a larger frictional force is generated at the center than at both ends of the platen roller 41. At this time, since a large force is applied to the central portion of the platen roller 41 in the recording medium conveyance direction S rather than both ends, the platen roller 41 has a convex shape in the recording medium conveyance direction S as shown in FIG. To bend. As a result, the platen roller 41 is bent in a direction in which the axis of the platen roller 41 and the heat generating portion row 9A coincide. FIG. 11 is a plan view schematically showing the positional relationship between the platen roller 41 and the heat generating portion row 9A during rotation.

  According to the thermal head X of the present embodiment, the platen roller 41 can be curved in the direction in which the axis of the platen roller 41 and the heat generating portion row 9A coincide with each other as described above. Therefore, it is possible to improve the uniformity of the force of pressing on the plurality of heat generating portions 9 and to suppress blurring of the print. Therefore, according to the thermal head X of the present embodiment, blurring of printing can be suppressed by a simple configuration in which a plurality of heat generating portions 9 are arranged along a curved curve convexly on the upper surface side of the substrate 7. Therefore, it is not necessary to change the photomask as in the conventional example, and an increase in manufacturing cost can be suppressed.

  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, as shown in FIG. 6, the central portion of the heat generating portion row 9 </ b> A is closer to one long side (the long left side in the illustrated example) of the substrate 7 than both end portions. The heating part row 9A is curved. However, as long as the heat generating portion row 9A is curved so as to be convex in a direction orthogonal to the main scanning direction of the thermal head X in plan view, the configuration is not limited thereto. Although not shown, for example, the substrate 7 may extend in a band shape along a curved line that is convex in a direction orthogonal to the main scanning direction in a plan view, similar to the heating unit row 9A.

  Further, in the thermal head X of the above embodiment, as shown in FIG. 4, a plurality of heat generations are performed along a curve curved convexly on the upper surface side of the substrate 7 (the side where the heat generating portions 9 are arranged as viewed from the substrate 7). In order to arrange the portion 9, the upper surface of the base plate portion 1a of the heat radiating body 1 is formed in a curved shape, but is not limited to this. For example, although not shown, the upper surface of the base plate portion 1a of the radiator 1 has a planar shape, and an adhesive layer (for example, adhesive, double-sided tape, etc.) between the upper surface of the base plate portion 1a and the lower surface of the substrate 7 is used. Spherical particles serving as spacers may be disposed therein, and the diameter of the particles disposed at the center portion may be larger than the diameter of the particles disposed at both ends in the longitudinal direction of the base plate portion 1a. By doing this as well, the upper surface of the substrate 7 has a curved surface shape, and the plurality of heat generating portions 9 are arranged along a curved curve convexly on the upper surface side of the substrate 7. Although not shown, for example, an adjusting means (for example, a feed screw) for pushing up the central portion in the longitudinal direction of the substrate 7 is provided on the base plate portion 1a of the radiator 1, and the upper surface of the substrate 7 is adjusted by the adjusting means. May be deformed so as to be convex.

X Thermal head 1 Radiator 3 Head substrate 5 Flexible printed wiring board (printed wiring board)
7 Substrate 9 Heating part 9A Heating part row

Claims (4)

A substrate,
A heat generating part array composed of a plurality of heat generating parts arranged on the substrate,
The heating element row is curved so as to be convex in a direction orthogonal to the main scanning direction in plan view,
The thermal head is characterized in that the plurality of heat generating portions are arranged along a curve curved in a convex shape on the side where the heat generating portions are arranged as viewed from the substrate.   The thermal head according to claim 1, wherein the substrate has a rectangular shape in plan view, and is formed such that a longitudinal direction of the substrate is along a main scanning direction.   3. The thermal head according to claim 1, wherein the substrate extends in a band shape along a curved line that is convex in a direction orthogonal to the main scanning direction in plan view. A thermal head according to any one of claims 1 to 3, and a platen roller that extends along a main scanning direction and presses a recording medium onto the plurality of heating portions,
A thermal printer characterized in that both ends of the platen roller are rotatably supported.

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