JP2011245683A - Thermal head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce electromagnetic interference in a thermal head with a printed wiring board.SOLUTION: The thermal head X includes: a head base body 3 having a substrate 7, a plurality of heating parts 9 arranged on the substrate 7, and a driving IC 11 provided on the substrate 7 and controlling the energization state of the heating parts 9; a printed wiring board 5 extended along the arrangement direction of the heating parts 9; and a conductive cover member 6 disposed on the printed wiring board 5 so as to cover the printed wiring board 5. The printed wiring board 5 includes a plurality of printed wiring lines 5b for supplying the electric current for heating the heating parts 9 or an electric signal for starting the driving IC 11. A facing region 6as of the cover member 6 facing a wiring region 5bs of the printed wiring line 5b extended along the arrangement direction of the heating parts 9 is divided by a through hole 6g formed on the cover member 6 over the whole width of the facing region 6as in the direction orthogonal to the arrangement direction of the heating parts 9.

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, in the thermal head described in Patent Document 1, a plurality of heat generating portions (heat generating resistors) are arranged on a substrate (insulating substrate). A drive IC is connected to the plurality of heat generating portions via individual electrodes. This drive IC controls the drive of the heat generating part based on an electric signal (recording data) supplied via a printed wiring board (flexible board).

JP-A-9-207367

  In the thermal head described in Patent Document 1, a cover member (head cover) is provided on a printed wiring board. The cover member and the printed wiring board are formed such that surfaces facing each other are parallel to each other. For this reason, an electric signal supplied via the printed wiring board flows parallel to the surface of the cover member facing the printed wiring board, so that a so-called parallel plate resonance occurs, and a high level of radiation noise at the resonance frequency. Will occur. As a result, there is a problem that electromagnetic interference occurs.

  The present invention has been made to solve the above problems, and an object of the present invention is to make it possible to reduce the occurrence of electromagnetic interference in a thermal head including a printed wiring board.

  A thermal head according to an embodiment of the present invention includes a substrate, a plurality of heat generating units arranged on the substrate, and a head base body provided on the substrate and having a drive IC that controls an energization state of the heat generating unit. The printed wiring board extending along the arrangement direction of the plurality of heat generating portions, and having conductivity, and is provided on the printed wiring board so as to cover at least a part of the upper surface of the printed wiring board. A cover member, and the printed wiring board has a plurality of printed wirings for supplying an electric current for operating the driving IC or an electric current for operating the driving IC. The wiring has a wiring region extending along an arrangement direction of the plurality of heat generating portions in a region of the printed wiring board facing the cover member, and is connected to the printed wiring board of the cover member. The surface to be extended extends along the wiring region of the printed wiring and has a facing region facing the wiring region, and the facing region of the cover member is orthogonal to the arrangement direction of the plurality of heat generating portions. It is divided by the through-hole formed in the said cover member over the whole width | variety of the said opposing area | region of a direction.

  In the thermal head according to an embodiment of the present invention, the cover member has a parallel region in which a surface facing the printed wiring board extends along the arrangement direction of the heat generating portions and extends parallel to the printed wiring board. The opposing region is located in the parallel region, and the parallel region has a width of the parallel region in a direction orthogonal to the arrangement direction of the plurality of heat generating portions by the through hole that divides the opposing region. It may be divided throughout.

  Further, in the thermal head according to an embodiment of the present invention, the cover member has a cross section in a direction perpendicular to the arrangement direction of the plurality of heat generating portions, the surface opposite to the surface facing the printed wiring board. The guide surface for guiding the recording medium to be printed may be formed by the inclined surface with respect to the printed wiring board.

  According to the present invention, it is possible to reduce the occurrence of electromagnetic interference in a thermal head including a printed wiring board.

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. 2 is a plan view of the thermal head of FIG. 1 with a cover member omitted. The plan view of the thermal head in FIG. 1 shows the position of the opposed region of the cover member. It is sectional drawing which shows the modification of the cover member shown in FIG. It is a top view which shows the modification of the cover member shown in FIG. It is sectional drawing which shows the modification of the cover member 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 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 FPC 5) and a cover member 6 disposed on the FPC 5. FIG. 4 is a plan view showing the thermal head X with the cover member 6 omitted.

  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 radiates a part of the 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. The head base 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 7 in plan view, a plurality of (24 in the illustrated example) heating units 9 provided on the substrate 7 and arranged along the longitudinal direction of the substrate 7, and the heating unit 9. And a plurality (three in the illustrated example) of driving ICs 11 arranged side by side on the substrate 7 along the arrangement direction.

  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.

  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 top surface of the substrate 7, and a raised portion 13b extending in a strip shape along the arrangement direction of the plurality of heat generating portions 9 and having a substantially semi-elliptical cross section. Yes. 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 FIG. 2, 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, and IC-FPC connection wiring 21. As shown in FIGS. A region (hereinafter referred to as an intervening region) having the same shape as the common electrode wiring 17, the individual electrode wiring 19, and the IC-FPC connection wiring 21, and a plurality (exposed from the common electrode wiring 17 and the individual electrode wiring 19 ( In the illustrated example, it has 24 areas (hereinafter referred to as exposed areas). In FIGS. 1 and 4, the intervening region of the electric resistance layer 15 is hidden by the common electrode wiring 17, the individual electrode wiring 19, and the IC-FPC connection wiring 21.

  Each exposed region of the electrical resistance layer 15 forms the heat generating portion 9 described above. The plurality of exposed regions (heat generating portions 9) are arranged in a row on the raised portions 13b of the heat storage layer 13, as shown in FIGS. For convenience of explanation, the plurality of heat generating portions 9 are illustrated in a simplified manner in FIGS. 1 and 4, 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 4, a common electrode wiring 17, a plurality of individual electrode wirings 19, and a plurality of IC-FPC connections are provided on the upper surface of the electric resistance layer 15 (more specifically, the upper surface of the intervening region). A wiring 21 is provided. The common electrode wiring 17, the individual electrode wiring 19, and the IC-FPC connection wiring 21 are formed of a conductive material. For example, any one metal of aluminum, gold, silver, and copper, or these It is made of an alloy.

  The common electrode wiring 17 is for connecting the plurality of heat generating portions 9 and the FPC 5. As shown in FIG. 4, the common electrode wiring 17 includes a main wiring portion 17 a extending along one long side (the left long side in the illustrated example) of the substrate 7, and one and the other short sides of the substrate 7. Extending along each of the two sub-wiring portions 17b whose one end (the left-hand end in the illustrated example) is connected to the main wiring portion 17a, and individually extending from the main wiring portion 17a toward each heat generating portion 9, The front end portion (right end portion in the illustrated example) has a plurality of (24 in the illustrated example) lead portions 17 c connected to the heat generating portions 9. And this common electrode wiring 17 electrically connects between FPC5 and each heat-emitting part 9 by connecting the other end part (right side edge part in FIG. 1) of subwiring part 17b to FPC5. ing.

  The plurality of individual electrode wirings 19 are for connecting each heat generating part 9 and the drive IC 11. As shown in FIGS. 2 and 4, each individual electrode wiring 19 has one end (left end in the illustrated example) connected to the heat generating unit 9 and the other end (right end in the illustrated example) is driven. In order to be arranged in the arrangement area of the ICs 11, the heating parts 9 individually extend in a band shape toward the arrangement area of the driving ICs 11. Then, the other end portion of each individual electrode wiring 19 is connected to the drive IC 11, whereby the heat generating portions 9 and the drive IC 11 are electrically connected. 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.

The plurality of IC-FPC connection wirings 21 are for connecting the driving IC 11 and the FPC 5. As shown in FIGS. 2 to 4, each IC-FPC connection wiring 21 has one end portion (left end portion in the illustrated example) disposed in the region where the drive IC 11 is disposed, and the other end portion (right end in the illustrated example). Part) extends in a strip shape so as to be arranged in the vicinity of the other long side of the substrate 7 (the long side on the right side in the illustrated example). The plurality of IC-FPC connection wires 21 are electrically connected between the drive IC 11 and the FPC 5 by connecting one end to the drive IC 11 and the other end to the FPC 5. Yes.

  More specifically, the plurality of IC-FPC connection wirings 21 connected to each driving IC 11 are configured by a plurality of wirings having different functions. Specifically, the plurality of IC-FPC connection wirings 21 include, for example, an IC power supply wiring for supplying a power supply current for operating the driving IC 11, a driving IC 11, and an individual electrode wiring connected to the driving IC 11. A ground electrode wiring for holding 19 at a ground potential (for example, 0 V to 1 V) and an electric signal for operating the driving IC 11 so as to control an on / off state of a switching element in the driving IC 11 to be described later are supplied. IC control wiring for this purpose.

  As shown in FIG. 4, the drive IC 11 is arranged corresponding to each group of the plurality of heat generating portions 9, and the other end portion (right end portion in the illustrated example) of the individual electrode wiring 19 and the IC-FPC. The connection wiring 21 is connected to one end (the left end in the illustrated example). This drive IC 11 is for controlling the energization state of each heat generating part 9, and has a plurality of switching elements inside, and is energized when each switching element is in an on state. A well-known thing which becomes a non-energized state in an OFF state can be used.

  Each drive IC 11 is provided with a plurality of switching elements (not shown) therein so as to correspond to each individual electrode wiring 19 connected to each drive IC 11. As shown in FIG. 2, each drive IC 11 has one connection terminal 11a (hereinafter referred to as the first connection terminal 11a) connected to each switching element (not shown) as an individual electrode wiring. 19 and the other connection terminal 11b (hereinafter, the second connection terminal 11b) connected to each switching element is connected to the ground electrode wiring of the IC-FPC connection wiring 21. It is connected. Thereby, when each switching element of the drive IC 11 is in the ON state, the individual electrode wiring 19 connected to each switching element and the ground electrode wiring of the IC-FPC connection wiring 21 are electrically connected.

  The electric resistance layer 15, the common electrode wiring 17, the individual electrode wiring 19 and the IC-FPC connection wiring 21 are formed by, for example, a conventionally well-known thin film forming method such as a sputtering method on the heat storage layer 13. After sequentially laminating by a technique, this laminate is formed by processing it into a predetermined pattern using a conventionally known photoetching or the like. The common electrode wiring 17, the individual electrode wiring 19, and the IC-FPC connection wiring 21 can be simultaneously formed by the same process.

  As shown in FIGS. 1 to 4, 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 example of illustration, this 1st protective layer 25 is provided so that the area | region on the left side of the upper surface of the thermal storage layer 13 may be covered. The first protective layer 25 is formed by corroding the area covered with the heat generating portion 9, the common electrode wiring 17 and the individual electrode wiring 19 due to adhesion of moisture or the like contained in the atmosphere, or contact with a recording medium to be printed. It is intended to protect against wear. 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. In FIGS. 1 and 4, for convenience of explanation, the formation region of the first protective layer 25 and the second protective layer 27 described later is indicated by a two-dot chain line, and illustration thereof is omitted.

  As shown in FIGS. 1 to 4, the common electrode wiring 17, the individual electrode wiring 19, and the IC-FPC connection wiring 21 are partially covered on the heat storage layer 13 formed on the upper surface of the substrate 7. Two protective layers 27 are provided. In the example of illustration, this 2nd protective layer 27 is provided so that the area | region on the right side rather than the 1st protective layer 25 of the upper surface of the thermal storage layer 13 may be covered. The second protective layer 27 corrodes the region covered with the common electrode wiring 17, the individual electrode wiring 19, and the IC-FPC connection wiring 21 due to oxidation by contact with the atmosphere or adhesion of moisture or the like contained in the atmosphere. It is for protecting from. The second protective layer 27 is formed so as to overlap the end portion of the first protective layer 25 as shown in FIG. 2 in order to more reliably protect the common electrode wiring 17 and the individual electrode wiring 19. . 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.

  As shown in FIGS. 3 and 4, the sub-wiring portion 17b of the common electrode wiring 17 connecting the FPC 5 described later and the end of the IC-FPC connecting wiring 21 are exposed from the second protective layer 27, As will be described later, the FPC 5 is connected.

  The second protective layer 27 is formed with openings 27a (see FIG. 2) for exposing the end portions of the individual electrode wiring 19 and the IC-FPC connection wiring 21 that connect the driving IC 11. These wirings are connected to the drive IC 11 via the part 27a. In addition, the drive IC 11 is connected to the individual electrode wiring 19 and the IC-FPC connection wiring 21 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.

  As shown in FIGS. 3 and 4, the FPC 5 extends along the arrangement direction of the plurality of heat generating portions 9 of the head base 3, and as described above, the sub wiring portion 17b of the common electrode wiring 17 and each IC-FPC. It is connected to the connection wiring 21. 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 electrically connected to an external power supply device and control device (not shown) via a connector 31. It has come to be. Such a printed wiring is generally formed of, for example, a metal foil such as a copper foil, a conductive thin film formed by a thin film forming technique, or a conductive thick film formed by a thick film printing technique. Moreover, the printed wiring formed by a metal foil, a conductive thin film, or the like is patterned by, for example, partially etching these by photoetching or the like.

  More specifically, as shown in FIGS. 3 and 4, the FPC 5 has a conductive bonding material in which each printed wiring 5 b formed inside the insulating resin layer 5 a is exposed at the end on the head base 3 side. For example, the sub-wiring portion of the common electrode wiring 17 is made of a bonding material 32 (see FIG. 3) made of, for example, a solder material or an anisotropic conductive material (ACF) in which conductive particles are mixed in an electrically insulating resin. It is connected to the end of 17b and the end of each IC-FPC connection wiring 21. In FIG. 4, several (seven in the illustrated example) of the plurality of printed wirings connected to the end of the sub-wiring portion 17 b of the common electrode wiring 17 and the end of each IC-FPC connection wiring 21 are shown. The printed wiring 5b is schematically shown by a broken line. The printed wiring 5b of the FPC 5 has a wiring region 5bs extending along the arrangement direction of the plurality of heat generating portions 9 (vertical direction in the illustrated example).

When each printed wiring 5b of the FPC 5 is electrically connected to an external power supply device and control device (not shown) via the connector 31, the common electrode wiring 17 is held at a positive potential (for example, 20V to 24V). The individual electrode wiring 19 is electrically connected to the positive terminal of the power supply apparatus, and the individual electrode wiring 19 is held at a ground potential (for example, 0 V to 1 V) via the ground electrode wiring of the driving IC 11 and the IC-FPC connection wiring 21. It is electrically connected to the negative terminal of the device. 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.

  Similarly, when each printed wiring 5b of the FPC 5 is electrically connected to an external power supply device and control device (not shown) via the connector 31, the IC power wiring of the IC-FPC connection wiring 21 is Similar to the common electrode wiring 17, it is electrically connected to the positive side terminal of the power supply device held at a positive potential. As a result, the power supply current for operating the drive IC 11 is supplied to the drive IC 11 by the potential difference between the IC power supply wiring and the ground electrode wiring of the IC-FPC connection wiring 21 to which the drive IC 11 is connected. Further, the IC control wiring of the IC-FPC connection wiring 21 is electrically connected to an external control device that controls the driving IC 11. As a result, the electrical signal transmitted from the control device is supplied to the drive IC 11. By operating the drive IC 11 so as to control the on / off state of each switching element in the drive IC 11 by this electric signal, each heat generating portion 9 can be selectively heated.

  A reinforcing plate 33 made of a resin such as polyimide resin or glass epoxy resin is provided between the FPC 5 and the radiator 1. The reinforcing plate 33 acts to reinforce the FPC 5 by being adhered to the lower surface of the FPC 5 with a double-sided tape, an adhesive, or the like (not shown). Further, the reinforcing plate 33 is bonded to the upper surface of the radiator 1 by a double-sided tape, an adhesive or the like (not shown), so that the FPC 5 is fixed on the radiator 1.

  The cover member 6 protects the connecting portion between the FPC 5 and the head base 3 or protrudes from the upper surface of the FPC 5 (for example, as shown in FIG. 3, for connecting the printed wiring 5b of the FPC 5 to the connector 31. This is for protecting the connection terminal 31a) and preventing the projections from coming into contact with the recording medium conveyed on the FPC 5. As shown in FIGS. 1 and 3, the cover member 6 is provided on the FPC 5 so as to cover the entire upper surface of the FPC 5. The cover member 6 includes a fixing portion 6a for fixing the cover member 6 on the FPC 5, a first protection portion 6b positioned on the head base 3 side from the fixing portion 6a, and a first protection portion with respect to the fixing portion 6a. It has the 2nd protection part 6c located in the opposite side to 6b.

  As shown in FIGS. 1 and 3, the first protection portion 6 b has a flat plate shape, extends along the arrangement direction of the plurality of heat generating portions 9, and from above the IC-FPC connection wiring 21 of the head base 3. It is formed over the FPC 5. Thereby, the connection part of FPC5 and the head base | substrate 3 is protected by the 1st protection part 6b. Further, as shown in FIG. 3, the first protective part 6 b has a height of the upper surface and the lower surface of the first protective part 6 b as it approaches the fixing part 6 a in the cross section in the direction orthogonal to the arrangement direction of the heat generating parts 9. Inclined to be higher. Thereby, in this embodiment, the guide surface for guiding the recording medium conveyed on the thermal head X is formed by the inclined surface formed by the upper surface of the first protection portion 6b. In addition, by inclining the lower surface of the first protective portion 6b with respect to the FPC 5 facing the lower surface in this way, the printed wiring 5b of the first protective portion 6b and the FPC 5 (more specifically, the heating portion 9). Parallel plate resonance is suppressed from occurring between the printed wiring 5b extending in a direction orthogonal to the arrangement direction. The inclination angle of the lower surface of the first protection part 6b with respect to the FPC 5 is preferably 2 degrees or more. If this inclination angle is smaller than 2 degrees, parallel plate resonance is likely to occur between the printed wiring 5b of the FPC 5 and the surface of the cover member 6 facing the FPC 5 as in the conventional example.

  The fixed portion 6a has a flat plate shape and extends along the arrangement direction of the plurality of heat generating portions 9 as shown in FIG. 1, and as shown in FIG. 3, the end of the first protective portion 6b on the fixed portion 6a side. The first protective part 6b is coupled by a first coupling part 6d which is positioned below the part and extends in the vertical direction.

  As shown in FIG. 3, the lower surface of the fixing portion 6a (the surface facing the FPC 5) extends in parallel to the FPC 5, and as shown in FIG. 5, along the wiring region 5bs of the printed wiring 5b of the FPC 5. It has a facing area 6as that extends and faces the wiring area 5bs. In FIG. 5, the position of the facing region 6as on the lower surface of the fixed portion 6a is indicated by a broken line. In the present embodiment, the lower surface of the fixed portion 6a corresponds to the parallel region in the present invention.

  As shown in FIGS. 1 and 3, the fixing portion 6a is formed with a plurality of through holes 6g that pass through the fixing portion 6a. The through hole 6g is formed across the entire width of the lower surface of the fixed portion 6a in a direction orthogonal to the arrangement direction of the plurality of heat generating portions 9, and the through hole 6g extends along the arrangement direction of the heat generating portions 9. The lower surface of the extending fixing portion 6a is divided. Further, as shown in FIGS. 3 and 5, the through hole 6 g is arranged at a position facing the wiring area 5 bs of the printed wiring 5 b of the FPC 5, and is a facing area in a direction orthogonal to the arrangement direction of the heat generating portions 9. By forming the through hole 6g over the entire width of 6as, the opposing region 6as on the lower surface of the fixed portion 6a is divided.

  The second protective part 6c has a flat plate shape, extends along the arrangement direction of the plurality of heat generating parts 9 as shown in FIG. 1, and is positioned above the fixed part 6a as shown in FIG. The second coupling portion 6e extends upward from the stationary portion 6a and is inclined toward the second protective portion 6c, and is coupled to the stationary portion 6a. The second protective portion 6c is inclined so that the height of the upper surface and the lower surface of the second protective portion 6c increases as it moves away from the fixed portion 6a, and up to the end of the FPC 5 on the side where the connector 31 is provided. It extends. Thereby, the protrusion (for example, connection terminal 31a) which protrudes from the upper surface of FPC5 is protected by the 2nd protection part 6c. In addition, by inclining the lower surface of the second protective portion 6c with respect to the FPC 5 facing the lower surface in this way, the second protective portion 6c and the printed wiring 5b of the FPC 5 are similar to the first protective portion 6b. More specifically, parallel plate resonance is prevented from occurring with (a region of the printed wiring 5b extending in a direction orthogonal to the arrangement direction of the heating portions 9). Further, as shown in FIG. 3, a third coupling portion 6f extending downward from this end portion is coupled to the end portion of the second protective portion 6c that is not coupled to the second coupling portion 6e. ing.

  The cover member 6 has a fixing screw 35 penetrating the fixing portion 6a, the FPC 5 and the reinforcing plate 33 in a screw hole (not shown) formed in the radiator 1 in a state where the fixing portion 6a is in contact with the upper surface of the FPC 5. It is fixed on the FPC 5 by tightening. Further, the fixing screw 35 acts so as to release the static electricity generated in the cover member 6 to the radiator 1. Further, for example, when a thermal printer is configured using the thermal head X, this cover can be configured by grounding the radiator 1 by electrically connecting the radiator 1 to the housing of the thermal printer or the like. Static electricity generated in the member 6 can be discharged.

  Moreover, this cover member 6 is formed with the material which has electroconductivity, for example, can be formed with metal materials, such as stainless steel and aluminum. In the present embodiment, the cover member 6 is formed by bending a metal plate made of stainless steel or the like. When the cover member 6 is formed by bending the metal plate in this way, the upper surface of the cover member 6 can be inclined at the same time as the lower surface of the cover member 6 (the surface facing the FPC 5) is inclined with respect to the FPC 5. . Therefore, when the guide surface for guiding the recording medium conveyed on the thermal head X is formed by the upper surface of the first protection portion 6b of the cover member 6 as in the present embodiment, the first protection of the cover member 6 is performed. Simultaneously with inclining the lower surface of the portion 6b, a guide surface of the recording medium can be formed by the upper surface of the first protective portion 6b.

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 9 is orthogonal to the conveyance direction of the recording medium to be printed.
Place. Then, while pressing the recording medium onto the heat generating portion 9 of the thermal head X (more specifically, on the first protective layer 25 on the heat generating portion 9) by a platen roller or the like, the heat generating portion 9 is moved while conveying the recording medium. Selectively generate heat. 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, as shown in FIG. 5, the through holes 6 g formed in the fixing portion 6 a of the cover member 6 are opposed regions 6 as in a direction orthogonal to the arrangement direction of the plurality of heat generating portions 9. It is formed over the entire width. The through hole 6g divides the facing region 6as of the cover member 6 that faces the wiring region 5bs of the printed wiring 5b of the FPC 5 and extends along the wiring region 5bs. Therefore, the length of the facing region 6as of the cover member 6 facing the wiring region 5bs of the printed wiring 5b can be shortened by the through hole 6g. In general, it is known that the resonance frequency due to parallel plate resonance varies depending on the lengths of regions facing each other of two conductors arranged in parallel. Therefore, by setting the length of the facing region 6as of the cover member 6 facing the wiring region 5bs of the printed wiring 5b to a predetermined length by forming the through hole 6g, the resonance frequency due to the parallel plate resonance is set. The frequency can be set such that electromagnetic interference is unlikely to occur. Therefore, according to the thermal head X of the present embodiment, it is possible to reduce the occurrence of electromagnetic interference.

  The occurrence of electromagnetic interference due to such parallel plate resonance becomes more conspicuous when a high-frequency electrical signal flows through the printed wiring board as the printing speed of the thermal head increases. In the case where an electrical signal including a high frequency electrical signal of 50 MHz or more flows through the printed wiring board, the effect of reducing the occurrence of electromagnetic interference according to the present invention becomes more remarkable.

  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 cover member 6 is provided on the FPC 5 so as to cover the entire upper surface of the FPC 5, but the present invention is not limited to this. For example, even if the cover member 6 is provided on the FPC 5 so as to cover at least a part of the upper surface of the FPC 5 and the wiring region 5bs of the printed wiring 5b is arranged in the region of the FPC 5 facing the cover member 6. Good.

  Further, in the thermal head X of the above embodiment, the through hole 6g is formed only in the fixing portion 6a of the cover member 6. However, the present invention is not limited to this. For example, as shown in FIGS. The through hole 6g may be formed in the second protection portion 6c so as to divide the facing region 6cs of the second protection portion 6c facing the wiring region 5bs of the printed wiring 5b. Since the lower surface of the second protective portion 6c of the cover member 6 shown in FIGS. 6 and 7 is inclined with respect to the opposing FPC 5, the gap between the second protective portion 6c and the wiring region 5bs of the printed wiring 5b. Parallel plate resonance is less likely to occur. However, even in such a case, a low level parallel plate resonance may occur. On the other hand, by forming the through hole 6g also in the opposing region 6cs of the second protective part 6c in this way, the length of the opposing region 6cs of the second protective part 6c is set to a predetermined length, and by parallel plate resonance. The resonance frequency can be set to a frequency at which electromagnetic interference hardly occurs. As a result, the occurrence of electromagnetic interference can be more effectively reduced.

Further, in the thermal head X of the above embodiment, only the lower surface of the fixing portion 6a of the cover member 6 extends in parallel to the FPC 5. However, the present invention is not limited to this. For example, as shown in FIG. In addition to the lower surface of the fixing portion 6a, the lower surface of the second protection portion 6c may also extend in parallel to the FPC 5. In this case, a through-hole 6g that opposes the wiring region 5bs of the printed wiring 5b and divides the opposing region 6cs extending along the wiring region 5bs is also formed in the second protection portion 6c. In this case, the lower surface of the fixed portion 6a and the lower surface of the second protective portion 6c correspond to the parallel region in the present invention.

  Moreover, in the thermal head X of the said embodiment, although the cover member 6 is formed by the bending process of a metal plate, it is not limited to this, For example, it forms by extruding metal materials, such as aluminum. May be. In the above embodiment, the surface (lower surface) facing the FPC 5 of the cover member 6 and the surface (upper surface) opposite to this surface are inclined at the same angle, but by using extrusion molding in this way, These surfaces can be inclined at different angles.

  In the thermal head X of the above-described embodiment, the common electrode wiring 17 and the IC-FPC connection wiring 21 provided on the substrate 7 of the head base 3 are electrically connected to the external power supply device and the control device through the FPC 5. However, the present invention is not limited to this. For example, various wirings of the head substrate 3 are connected to the outside via a hard printed wiring board, not a flexible printed wiring board having flexibility like the FPC 5. It may be electrically connected to a power supply device or the like. In this case, for example, the common electrode wiring 17 and the IC-FPC connection wiring 21 of the head substrate 3 may be connected to the printed wiring of the printed wiring board by wire bonding or the like. Also in this case, the cover member 6 is provided on a hard printed wiring board as in the case of the FPC 5.

X Thermal head 1 Radiator 3 Head substrate 5 Flexible printed wiring board (printed wiring board)
5b Printed wiring 5bs Wiring area 6 Cover member 6as Opposing area 6g Through hole 7 Substrate 9 Heating part 11 Drive IC

Claims (3)

A head base having a substrate, a plurality of heat generating units arranged on the substrate, and a drive IC provided on the substrate for controlling the energization state of the heat generating unit;
A printed wiring board extending along the arrangement direction of the plurality of heat generating parts;
It has conductivity, and includes a cover member provided on the printed wiring board so as to cover at least a part of the upper surface of the printed wiring board,
The printed wiring board has a plurality of printed wirings for supplying a current for heating the plurality of heat generating portions or an electric signal for operating the driving IC,
The printed wiring has a wiring region extending along an arrangement direction of the plurality of heat generating portions in a region of the printed wiring board facing the cover member,
The surface of the cover member that faces the printed wiring board has a facing region that extends along the wiring region of the printed wiring and faces the wiring region.
The facing region of the cover member is divided by a through-hole formed in the cover member over the entire width of the facing region in a direction orthogonal to the arrangement direction of the plurality of heat generating portions. Thermal head. The cover member has a parallel region in which a surface facing the printed wiring board extends along the arrangement direction of the heat generating portions and extends in parallel to the printed wiring board, and the facing region is located in the parallel region. And
2. The parallel region is divided across the entire width of the parallel region in a direction orthogonal to the arrangement direction of the plurality of heat generating portions by the through hole that divides the opposing region. The thermal head described in 1. The surface of the cover member opposite to the surface facing the printed wiring board is inclined with respect to the printed wiring board in a cross section in a direction orthogonal to the arrangement direction of the plurality of heat generating portions. 3. The thermal head according to claim 1, wherein a guide surface for guiding a recording medium to be printed is formed by the side surface.

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