JP2006305974A - Thermal head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the visibility of a positioning marker from being spoiled even when the surface of a protective layer is polished. <P>SOLUTION: This thermal head of a folded back structure comprises a plurality of contact conductors, a plurality of individual electrodes and common electrodes, a common line, and the protective layer. In this case, a plurality of the contact conductors conductively connect a pair of adjacent heating resistors. A plurality of the individual electrodes and the common electrodes turn on a pair of the heating resistors through the contact conductors. The common line extends in the arrangement direction, and commonly connects a plurality of the common electrodes, and to which power is fed from both ends of the arrangement direction. The protective layer covers the total region on a board. In the thermal head, the positioning marker is provided at a position which is in a region on the outside of a protruding shape section, is the central position in a direction being orthogonal to the arrangement direction of a plurality of the heating resistors, and is positioned away by a specified length from the apex point of the protruding shape in the direction being orthogonal to the arrangement direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a thermal head used in, for example, a thermal transfer printer, and more specifically to a thermal head having a positioning marker for setting a reference angle, a reference position, and the like for mounting.

  The thermal head has a heat storage layer made of a highly heat-insulating material such as glass, a plurality of heating resistors that generate heat when energized, and a common electrode that is conductively connected in common to all the heating resistors. And a plurality of individual electrodes individually connected to each heat generating resistor, and printing operation is performed by pressing the heat generating resistor heated through the common electrode and the individual electrodes to an ink ribbon or a print medium (thermal paper). To do. In conventional thermal heads, in order to improve printing quality, the substrate itself is made convex or a convex shape is formed with a heat storage layer on a flat substrate, so that contact stress is applied to the print medium during printing. Such a convex substrate type is often used. Further, the common electrode and the individual electrode are generally connected to both ends in the resistance length direction of the heating resistor and arranged in a straight line in the resistance length direction, but the substrate size is small and the heating resistor is mounted on the substrate. A structure in which the common electrode is folded back has also been proposed so that the common electrode can be disposed at the end.

  5A and 5B are a sectional view and a plan view (excluding a protective layer) showing a thermal head having a conventional folded structure. In the folded structure, one print dot portion D is constituted by two heating resistors 105a and 105b connected to each other by a U-shaped folded conductor 110, and is connected to the other end of one heating resistor 105a. The individual electrode 107 and the common electrode 108 are connected to the other end of the other heating resistor 105b. Each common electrode 108 is connected to a common line 109 extending long in a direction parallel to the arrangement direction (main scanning direction) of the print dot portions D, and power is supplied from both ends of the common line 109 in the longitudinal direction. The thermal head shown in FIG. 5 can be formed by the following steps, for example.

  First, a substrate 102 provided with a partially convex heat storage layer 103 is prepared. Next, after the resistor layer 104 and the Al conductor layer C are entirely formed on the heat storage layer 103, a part of the Al conductor layer C and the resistor layer 104 is removed, and a folded conductor to be formed, individual electrodes, The Al conductor layer C and the resistor layer 104 are left in the schematic shape of the common electrode and the common line. The Al conductor layer C is formed with a thickness of about 1 μm in order to reduce electrode resistance (in order to suppress increase in electrode resistance due to downsizing of the head). Subsequently, the Al conductor layer C located on the convex shape of the heat storage layer 103 is removed, and an open portion α that exposes a part of the surface of the resistor layer 104 is formed. The exposed regions of the surface of the resistor layer 104 become heating resistors 105, respectively. Through this open portion α, the Al conductor layer C includes a U-shaped folded conductor 110 that conductively connects one end side of a pair of adjacent heating resistors 105 (105a, 105b), and the same pair of heating resistors 105a, Separated into an individual electrode 107 and a common electrode 108 connected in the same direction to the other end side of 105b. The common electrode 108 and the common line 109 are integrally formed. After the opening α is formed, a wear-resistant protective layer 111 that covers the folded conductor 110, the individual electrode 107, the common electrode 108, and the common line 109 is formed.

  Since the Al conductor layer C is as thick as about 1 μm, a step is formed at both ends of the open portion α, that is, at each boundary between the heating resistor 105 and the folded conductor 110, and this step is also formed on the surface of the wear-resistant protective layer 111. Appears as part 111a. If there is a step in the vicinity of the heating resistor 105, the contact efficiency between the print medium and the heating resistor 105 is deteriorated. Therefore, the step portion 111a of the wear-resistant protective layer 111 is polished (polished), and the printing medium The contact surface is smoothly formed. Through the above processing, the thermal head shown in FIG. 5A is obtained.

When such a thermal head is mounted on a thermal transfer printer or the like, it is necessary to set and adjust the position and angle of the heating resistor 105 with respect to the platen and the like. On the other hand, in the conventional thermal head, on the extension of the arrangement of the heating elements and the feeding electrodes, a horizontally long marker and a vertically long marker are formed on the same surface as the heating elements and the feeding electrodes (Patent Document 1), It is known that a concave alignment marker for improving the dimensional accuracy of a glaze layer is formed at both ends of a ceramic substrate (Patent Document 2).
JP 2002-225324 A JP 2004-114530 A

  However, when the positioning marker is formed on the extension connecting the center position of the heating resistor 105 of the thermal head, the abrasion-resistant protective layer surface on the positioning marker may be polished when polishing the stepped portion 111a. . In such a case, the positioning marker may not be visible through the wear-resistant protective layer.

  The present invention has been made in view of such conventional problems, and an object of the present invention is to obtain a thermal head in which the visibility of the positioning marker is not impaired even when the surface of the protective layer is polished.

  The present invention has been made paying attention to the point that polishing of the thermal head is limited to the convex portion. That is, the present invention provides a plurality of heating resistors that generate heat when energized, wherein the substrate itself has a convex shape or a flat heat storage layer formed on a flat substrate, and is arranged at a predetermined pitch on the convex shape of the heat storage layer. A thermal head having a convex shape of the heat storage layer and a wear-resistant protective layer covering a substrate including the heating resistor, the center position in the direction orthogonal to the arrangement direction of the plurality of heating resistors or the apex of the convex shape It is characterized in that a positioning marker is provided in a region outside the convex shape portion that is a predetermined length away from the position in a direction orthogonal to the arrangement direction.

  More practically, a plurality of contact conductors that conductively connect the pair of adjacent heating resistors, a plurality of individual electrodes and common electrodes that energize the pair of heating resistors via each contact conductor, and the arrangement direction A thermal head having a folded structure having a common line that is fed in common to the plurality of common electrodes and fed from both ends in the arrangement direction, and the positioning marker is more than the individual electrodes and the common electrodes. It is provided in one or both outer regions in the arrangement direction.

  Each of the heating resistors is formed closer to the contact conductor than the apex of the convex portion.

  The positioning marker includes a portion formed of the same material in the same process as the heating resistor, and a portion formed of the same material in the same process as the contact conductor, individual electrode, common electrode, and common line on the portion. It is preferable to form by one or both of these. Since the positioning marker is formed in the same process as the heating resistor or the electrode, the manufacturing process is not increased and the accuracy is high.

  A plurality of heating resistor groups arranged at a predetermined pitch, a common electrode group that applies a common potential to all the heating resistors of the heating resistor group, and individual connections individually connected to the heating resistors of the heating resistor group In a thermal head having a folded structure in which the common electrode group and the individual electrode group are arranged at intervals for each of a plurality of small group electrode groups, the positioning marker is used as the heating resistor group. It is provided in an empty area restricted by the small group electrode group.

  The positioning marker may be provided in an empty area sandwiched between the adjacent heating resistor group and the small group electrode group.

  The positioning marker includes a part formed of the same material in the same process as the heating resistor, and one of the part formed of the same material in the same process as the contact conductor, the individual electrode, and the common electrode on the part or It is preferable to form both.

  Even if the surface of the convex protective layer is polished, the surface of the protective layer above the positioning marker is not polished, so that the visibility of the positioning marker is not impaired.

  1 and 2 are a plan view showing an outline of an embodiment of the thermal head of the present invention and a cross-sectional view taken along a cutting line II-II in FIG. The thermal head 1 includes a plurality of printing dot portions D arranged in a line at predetermined intervals in the vertical direction in FIG. 1, and performs a printing operation by applying heat of each printing dot portion D to thermal paper or an ink ribbon.

  The thermal head 1 has a heat storage layer 3 made of a heat insulating material such as glass on a substrate 2 made of Si, a ceramic material, a metal material or the like and having excellent heat dissipation, and the heat storage layer 3 shown in FIG. A plurality of heating resistors 4 arranged in a line at a minute interval in the left-right direction are provided.

The heat storage layer 3 is formed of a heat insulating material such as glass, for example, and has a convex portion 3a that forms a convex shape on one end side of the substrate 2, and a uniform film that is continuous with the convex portion 3a and has a uniform film thickness. And a thick portion 3b. The plurality of heating resistors 4 are located in the middle of the inclined surface separated by a predetermined length from the apex position on the convex shape portion 3a of the heat storage layer 3 to generate heat when energized. Each heating resistor 4 is a part of a resistor layer formed entirely on the heat storage layer 3 using a cermet material such as Ta ₂ N or Ta—SiO ₂ , and the surface thereof is an insulating barrier layer 5. Covered by. The insulating barrier layer 5 is made of an insulating material such as SiO ₂ , SiON, or SiAlON, for example, and defines the planar size (length dimension, width dimension) of each heating resistor 4. In the present embodiment, one printing dot portion D is formed by a pair of adjacent heating resistors 4 (4a, 4b), and the plurality of printing dot portions D are connected to the energizing direction (sub-scanning direction) of the heating resistor 4. They are arranged in rows in the orthogonal direction (left-right direction in FIG. 1, main scanning direction). As the convex shape, the substrate 2 itself having a convex shape may be used.

  The individual electrode 7 is provided for each printing dot portion D and is formed to extend long in the energizing direction (vertical direction in FIG. 1, sub-scanning direction) of each heating resistor 4a. The individual electrode 7 includes a bonding pad formed at the end opposite to the heating resistor 4 a side and a corresponding bonding pad of the drive unit 21 mounted on the PCB 20 separate from the heat dissipation board 2. The wires 11 are connected by bonding.

  The drive unit 21 includes a plurality of switching elements (drive ICs) for switching between energization / non-energization of the corresponding individual electrodes 7 via a plurality of bonding pads wire-bonded to the individual electrodes 7, a plurality of external connection terminals, and the like. Have. FIG. 1 schematically shows the structure of the thermal head 1, and the wire 11 connecting the bonding pad of the individual electrode 7 and the bonding pad of the drive unit 21 is actually very small, about 50 μm. It is provided at intervals.

  The common electrode 8 is provided for every two adjacent print dot portions D, and is disposed between the individual electrodes 7 provided for the two print dot portions D, respectively. The common electrode 8 includes a U-shaped portion connected to two adjacent heating resistors 4b and a straight line extending from the U-shaped portion to a direction parallel to the resistance length direction of the heating resistor 4b (sub-scanning direction). And a substantially Y-shape having a portion. Each common electrode 8 is connected to the common line 9 at the end opposite to the heating resistor 4b side.

  The common line 9 extends in the arrangement direction of the plurality of print dot portions D (left and right direction in FIG. 1, main scanning direction) and is connected in common to the plurality of common electrodes 8, and extends in the longitudinal direction (left and right direction in FIG. 1). Both ends are respectively connected to a power source 22 mounted on the PCB 20 by wires 11 by wire bonding. Power is supplied from the power source 22 to all the printing dot portions D through the wire 11, the common line 9, and each common electrode 8.

  In this thermal head 1, the heating resistor 4, the individual electrode 7, the common electrode 8 and the common line 9 are formed as one of the Al conductor layers in the same process.

  Further, the thermal head 1 is provided with a positioning marker 12 on the uniform film thickness portion 3b outside the individual electrode 7 at one end portion (left end in FIG. 1). In the same process of forming the heating resistor layer 4 ', the positioning marker 12 is formed on the individual pedestal 12a formed of the same cermet material as the heating resistor layer 4' and extending in the main scanning direction. In the same process as the common electrode 8 and the common line 9, the dot portion 12b is formed by the same Al conductor. A plurality of dot portions 12b are provided in the main scanning direction, and the center of the dot portion 12b is a preset distance from a straight line passing through the center of each heating resistor 4 in the arrangement direction to a flat portion on the PCB 20 side. They are separated by d. A plurality of dot portions 12b are preferably provided in the main scanning direction.

  Further, in the vicinity of the positioning marker 12, a vertex marker 13 indicating a vertex at the vertex position of the convex portion 3 a is provided. This vertex marker 13 is also formed simultaneously in the same process as the positioning marker 12.

On the insulating barrier layer 5, the contact conductor 6, the individual electrode 7, the common electrode 8, the common line 9, the positioning marker 12, and the apex marker 13, for example, a wear resistant material such as SiAlON or Ta ₂ O ₅ is used. A wear protection layer 14 is formed. The wear-resistant protective layer 14 protects the insulating barrier layer 5 and the conductor layers such as the contact conductor 6, the individual electrode 7, the common electrode 8, and the common line 9 from friction generated during head operation. Since the thickness of the wear-resistant protective layer 14 is substantially constant, the surface of the wear-resistant protective layer 14 is transferred with the concavo-convex shape of the substrate surface, and the convex portion 14a is formed along the convex portion 3a. (Fig. 2). In particular, the convex portion 14 a is formed with a stepped portion 14 b having irregular irregularities on the surfaces of the heating resistor 4 and the insulating barrier layer 5. Therefore, the surface of the convex portion 14a of the wear-resistant protective layer 14 including the stepped portion 14b is polished (polished) to be smooth. This polishing is usually performed by using a roller-shaped or disk-shaped grindstone or brush whose diameter is much larger than the width of the stepped portion 14b (the length in the direction orthogonal to the arrangement direction of the heating resistors 4). Since the process is performed over the entire width in the arrangement direction of the bodies 4, polishing is performed up to the surface region of the convex portion 14 a where the heating resistor 4 and the insulating barrier layer 5 do not exist. However, in the thermal head 1 of this embodiment, since the positioning marker 12 is formed in a flat region that is not polished, outside the convex portion 14a, there is no possibility that the positioning marker 12 cannot be visually recognized.

  FIG. 3 shows an outline of another embodiment of a thermal head to which the present invention is applied, in which (A) is a side view and (B) is a plan view (excluding a protective layer). The thermal head of this embodiment is composed of a plurality of heating resistor groups with a plurality of heating resistors 4 as a group, individual electrodes 7 connecting the heating resistors 4a of each heating resistor group, and two adjacent two. The common electrode 8 connecting the two heating resistors 4b is a small group electrode group, converged in the opposite direction to the heating resistors 4a and 4b, and the ends are narrower than the pitch of the heating resistors 4a and 4b. The pitch is formed. Between the outermost heating resistor group and the small group electrode group, a substantially triangular vacant area is formed as a vacant area where no electrodes, heating elements, etc. exist. Further, although not shown, a substantially triangular empty area where no electrode exists is formed between each heating resistor group and each heating resistor group.

  In the embodiment of the present invention, the positioning marker 12 (the pedestal portion 12a) is formed in a flat area outside the convex shape portion within the substantially triangular open area regulated by the outermost heating resistor group and the small group electrode group. And a dot portion 12b). In the illustrated embodiment, the positioning marker 12 is provided in a substantially triangular region outside the outermost heating resistor group. It is preferable to provide a plurality of dot portions 12b in the main scanning direction. In the illustrated embodiment, a plurality of heating resistors 4 (4a, 4b) are provided at the same pitch. The positioning marker 12 may be provided in a substantially triangular area formed between the heating resistor group and the heating resistor group. The positioning marker 12 may be provided in at least one place, but may be provided in a plurality of places or all substantially triangular regions. If it is provided in a plurality of locations or all substantially triangular regions, it is convenient because the positioning marker 12 at the most convenient position can be used.

  In the above embodiment, the positioning marker 12 is composed of the rectangular pedestal portion 12a formed of the same material in the same process as the heating resistor layer and the dot portion 12b formed of the same material in the same process as the conductor layer. These shapes can be deformed, and both may be the same shape, or may be formed of only one of the heating resistor layer and the conductor layer. The pedestal 12a does not have to be rectangular, but in the case of a rectangle, the long side is set in parallel with the main scanning direction and the short side is set in parallel with the sub scanning direction, whereby the reference in the main scanning direction and the sub scanning direction is set. It is convenient. The dot part 12b may not be circular, but may be square, rectangular, or any other shape.

  The thermal head 1 is mounted on a thermal transfer printer or the like so that the heating resistor 4 is closest to the surface of the platen roller 40 (FIG. 4). At that time, the angle and the position are adjusted so that the normal line standing at the center of the heating resistor 4 coincides with the normal line standing on the surface of the platen roller 40. In the thermal head 1 of this embodiment, if the angle formed between the normal line standing at the convex vertex T of the surface of the convex portion 14a and the normal line standing at the center of the heating resistor 4 is the inclination angle θ, the thermal head 1 Is designed to be optimal when it is tilted by the tilt angle θ. However, the tilt angle θ may cause an error due to a manufacturing error. Therefore, in this embodiment, the positioning marker 12 can be used when measuring the actual inclination angle θ.

  Although the embodiment in which the present invention is applied to a thermal head having a folded structure has been described above, the present invention can also be applied to a thermal head having no folded structure. In the thermal head 1 of this embodiment, the heating resistor 4 is defined by the insulating barrier layer 5, but the present invention can also be applied to a thermal head that does not have the insulating barrier layer 5.

It is a top view which shows the outline | summary of embodiment of the thermal head to which this invention is applied. It is sectional drawing which follows the cutting line II-II of FIG. The outline | summary of other embodiment of the thermal head to which this invention is applied is shown, (A) is a side view, (B) is a top view. It is a side view explaining a mode in the case of mounting the thermal head on a thermal transfer type printer. The thermal head of the conventional folding structure is shown, (A) is sectional drawing, (B) is a top view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermal head 2 Board | substrate 3 Thermal storage layer 3a Convex shape part 3b Uniform film thickness part 4 Heating resistor 4a 4b Heating resistor 5 Insulating barrier layer 6 Contact conductor 7 Individual electrode 8 Common electrode 9 Common line 11 Wire 12 Positioning marker 12a Base part 12b Dot portion 13 Vertex marker 14 Wear-resistant protective layer 14a Convex shape portion 14b Stepped portion 20 PCB
21 Drive unit

Claims (7)

A heat storage layer having a convex shape is formed on a substrate having a convex shape or a flat substrate, and a plurality of heating resistors that are arranged at a predetermined pitch on the convex shape of the heat storage layer, In a thermal head having a convex shape and a wear-resistant protective layer covering a substrate including a heating resistor,
A positioning marker is provided in a region outside the convex shape portion that is a predetermined distance away from a center position in a direction orthogonal to the arrangement direction of the plurality of heating resistors or a vertex position of the convex shape in a direction orthogonal to the arrangement direction. This is a thermal head. The thermal head according to claim 1, wherein a plurality of contact conductors that conductively connect the pair of adjacent heating resistors, a plurality of individual electrodes and a common electrode that energize the pair of heating resistors via each contact conductor, A thermal head having a folded structure that extends in the arrangement direction and is commonly connected to the plurality of common electrodes and having a common line fed from both ends of the arrangement direction, wherein the positioning marker includes the individual electrode and the common A thermal head provided in one or both outer regions in the arrangement direction with respect to the electrodes. 3. The thermal head according to claim 2, wherein each of the heating resistors is formed closer to the contact conductor than the apex of the convex portion. 3. The thermal head according to claim 2, wherein the positioning marker is a portion formed of the same material in the same process as the heating resistor, and on the portion, the contact conductor, the individual electrode, the common electrode, and the common line are the same. A thermal head formed by one or both of parts formed of the same material in the process. The thermal head according to claim 1 or 3, wherein a plurality of heating resistor groups arranged at a predetermined pitch, a common electrode group that applies a common potential to all the heating resistors of the heating resistor group, and the heating resistor groups A thermal head having a folded structure in which the common electrode group and the individual electrode group are arranged at intervals for each of a plurality of small group electrode groups. The positioning marker is a thermal head provided in an empty area regulated by the heating resistor group and the small group electrode group. 6. The thermal head according to claim 5, wherein the positioning marker is provided in an empty area sandwiched between the adjacent heating resistor group and the small group electrode group. 7. The thermal head according to claim 5, wherein the positioning marker includes a portion formed of the same material in the same step as the heating resistor, and the same step as the contact conductor, the individual electrode, and the common electrode on the portion. A thermal head formed by one or both of parts formed of the same material.

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