JP5595697B2 - Thermal head - Google Patents

Description

  The present invention relates to a thermal head used in a printing apparatus such as a thermal printer, and more particularly to a thermal head that facilitates noise reduction during operation.

  The thermal head is an output device that uses the heat generated by the heat generating portion to form an image made up of characters or the like by, for example, an ink ribbon thermal transfer method or a thermal recording method. In general, this thermal head includes a resistor substrate portion provided with a heat generating portion for image formation or overcoat processing, and a drive circuit substrate portion mounted with a drive IC for energizing the heat generating portion. The structure is arranged on one main surface of the heat dissipation board. In recent years, thermal heads that are attracting attention for use in video printers, imagers, seal printers, and the like have been developed in various ways because of their advantages such as low noise and low running cost.

  An example of a conventional thermal head will be described with reference to FIG. FIG. 4 is an enlarged cross-sectional view in the direction (sub-scanning direction) in which the recording medium is conveyed, with the vicinity of the heat generating portion of the thermal head extracted. The thermal head extends to a required length along a direction (main scanning direction) orthogonal to the sub-scanning direction.

  As shown in FIG. 4, a glaze layer 102 that functions as a heat storage layer or a smooth layer is provided on a support substrate 101 made of ceramic or the like. A heating resistor 103 is provided on the glaze layer 102, and a first electrode 104 a and a second electrode 104 b are formed on the heating resistor 103 so as to overlap with each other. Here, each of the pair of electrodes 104 has a gap G having a predetermined length at the lead edge portion, and the heating resistor exposed in the gap G becomes the heating portion 105. The pair of electrodes 104 serving as energization electrodes of the heat generating portion 105 and the heat generating portion 105 serve as heat generating elements, and an array is formed with a required dot density (dpi; dot per inch) in the main scanning direction of the thermal head in the resistor substrate portion. Are arranged in a shape. Further, a protective layer 106 made of an insulating material or the like for protecting the heating element array is formed by sputtering or the like. A thermal head having the above-described configuration is described in, for example, Patent Document 1.

  In image formation or overcoat processing on a recording medium using, for example, a thermal transfer ink ribbon by the operation of the thermal head, an ink ribbon and a recording medium (not shown) are stacked in that order on the protective layer 106 of the thermal head. It is sandwiched / slidably contacted with a platen roller (not shown). Then, it is conveyed at a predetermined speed in the sub-scanning direction. In the narrow pressure / sliding contact, the ink ribbon is heated by the heat generating portion 105 that generates heat by the energization pulse, and printing on the recording medium is performed by thermal transfer of the ink ribbon. In forming an image or the like using a thermal recording medium, the thermal recording medium is sandwiched / slided between the protective layer 106 of the thermal head and a platen roller (not shown) and heated in the same manner. Printing is performed.

  In the thermal head described above, since the heating resistor 103, the pair of electrodes 104, the protective layer 106, and the like are formed by using a thin film forming technique such as vapor deposition or sputtering, the heating element can be easily miniaturized and image formation can be performed. It is a structure suitable for high definition in. However, as shown in FIG. 4, the concave portion 107 and the stepped portions 108 (108 a and 108 b) are inevitably generated on the surface of the protective layer 106 corresponding to the steps of the lead edge portions of the pair of electrodes 104.

  The formation of the concave portion 107 and the step portion 108 will be described by taking as an example a thermal head having a structure in which one heating element prints two dots as shown in FIG. FIG. 5 is a perspective view in which a part of the resistor substrate portion of the thermal head is extracted, and is shown in a form seen through the protective layer 106 in FIG. As shown in FIG. 5, one heating element has a first electrode 104a as an individual electrode, a third electrode 104c as a common electrode, and a U-shaped folded electrode corresponding to the second electrode 104b therebetween. And has two heat generating portions 105 between the individual electrode and the common electrode. In this case, the two heat generating sections 105 perform two-dot printing by energization pulses applied to the first electrode 104a and the third electrode 104c.

  The above-described heating elements are arranged in the required number in the main scanning direction of the thermal head in an array. In addition, the first electrode 104a and the second electrode 104b to be the pair of electrodes 104, and the second electrode 104b and the third electrode 104c to be the pair of electrodes 104, and the lead edge portions thereof. Are arranged substantially linearly in the main scanning direction in the thermal head. For this purpose, on the surface of the protective layer 106 covering these energized electrodes and the heat generating portion, a concave portion 107 and a step portion 108 extending in a strip shape in the main scanning direction are formed along the lead edge portion of the electrode. Will be.

  The concave portion 107 and the stepped portion 108 are formed in a case where one heating element is composed of one heating element 105, a pair of electrodes 104 of a first electrode 104a and a second electrode 104b, and prints one dot. Even if it occurs, it occurs in the same way.

JP 2005-297343 A

  However, in the formation of an image or the like using the above-described conventional thermal head, the ink ribbon or the thermal recording medium hits the step 108 extending along the main scanning direction of the thermal head, and the ink ribbon or the thermal recording medium. Residues generated by volatilization due to overheating are easily formed in the step portion 108. And such a residue accumulates in this step part 108 area | region by operation | movement of a printing apparatus, The one part peels and a peeling sound is generated. Alternatively, an abnormal noise is generated in which the ink ribbon or the thermal recording medium that is in sliding contact with the protective layer 106 is rubbed against the residue of the step portion 108. For this reason, it has been difficult for conventional thermal heads to reduce noise during operation.

  In particular, in image formation or overcoat processing on a recording medium using an ink ribbon, as described above, the ink ribbon and the recording medium are overlapped in this order to form a narrow pressure / sliding contact between the protective layer 106 and the platen roller. receive. Moreover, the above-described recess 107 and step 108 on the surface of the protective layer 106 exist in the nip area with the platen roller. For this reason, the lubricant on the ink ribbon (mainly on the back surface side in sliding contact with the protective layer 106) heated excessively at the center of the heat generating portion 105 is likely to volatilize, and the volatilized lubricant is adjacent to the heat generating portion 105. It adheres to the part 108. And this deposit | attachment tends to accumulate as a residue in the step part 108b located in the downstream in which an ink ribbon and a recording medium are conveyed.

  The present invention has been made in view of the above-described circumstances, and it is easy to form a residue by an ink ribbon or a heat-sensitive recording medium at a step portion on the surface of the protective layer covering the heat generating portion of the thermal head. The purpose is to suppress. And it aims at making noise reduction of the thermal head easy in operation of a printing apparatus.

In order to achieve the above object, a thermal head according to the present invention comprises:
A heat-retaining layer on a support substrate; a heat-generating part formed of a thin-film heating resistor formed on the heat-retaining layer; an electrode for energizing the heat-generating part; and a protective layer covering the heat-generating part. A thermal head used in a printing apparatus for performing a printing process or an overcoat process after the printing process,
The electrodes are arranged to extend in a comb-tooth shape in the conveyance direction of the recording medium, and the electrodes are formed from a base portion extending in one direction of the support substrate and a comb-tooth portion extending from the base portion in a comb-tooth shape. Consisting of a common electrode and an individual electrode whose one end portion enters between the comb teeth portions,
The heating resistor of the heat generating part is disposed between the lead edges of the common electrode and the individual electrode, and has a pattern longer in the transport direction than the distance between the lead edges of the electrodes , leaving a space in the transport direction. is divided into three portions or more, and is configured central portion of its divided heating resistors has become shortest in the transport direction, and is energized in a direction intersecting the conveying direction Te .

  According to the configuration of the present invention, the formation of residue due to the ink ribbon or the heat-sensitive recording medium is easily suppressed at the step portion of the surface of the protective layer covering the heat generating portion of the thermal head. And it becomes easy to reduce the noise of the thermal head during operation of the printing apparatus.

The perspective view which extracted a part of resistor board | substrate part of the thermal head for describing embodiment of this invention. The perspective view which extracted a part of resistor board | substrate part of another thermal head for describing embodiment of this invention. The temperature distribution figure for demonstrating the heat_generation | fever characteristic of the heat generating part of the thermal head in embodiment of this invention. FIG. 6 is a partially enlarged cross-sectional view of the vicinity of a heat generating portion in a conventional thermal head. The perspective view which extracted a part of resistive substrate part of an example of the thermal head of a prior art.

  An embodiment of the present invention will be described with reference to FIGS. 1 and 2. Here, FIGS. 1 and 2 are perspective views in which a part of a resistor substrate portion of a thermal head having a different structure is extracted, and is shown in a perspective view of the protective layer as in the case of FIG. 5 described in the prior art. ing. Hereinafter, parts that are the same or similar to each other are denoted by common reference numerals, and redundant description is partially omitted. However, the drawings are schematic and ratios of dimensions and the like are different from actual ones.

As shown in FIG. 1, an insulating glaze layer 12 that functions as a heat storage layer or a smooth layer is provided on a support substrate 11 made of ceramic or the like. The first heating resistor 13a, the second heating resistor 13b, and the third heating resistor 13c are divided on the glaze layer 12 in the sub-scanning direction of the head substrate in the thermal head, and are parallel to the main scanning direction. It is arranged. Here, the first heating resistor 13a and the second heating resistor 13b is separated by the first space S _1, Similarly, the second heating resistor 13b and the third heat generating resistor 13c is the second It is separated by a space S _2. The glaze layer 12 is exposed in these separation regions.

  A common electrode 14 is formed which includes a base portion 14a extending in one direction of the support substrate 11, for example, a main scanning direction, and a comb tooth portion 14b extending from the base portion 14a in a comb-tooth shape. Further, the individual electrodes 15 are arranged in a comb-like shape between the comb-tooth portions 14 b of the common electrode 14. These comb-tooth portions 14b and the individual electrodes 15 are electrically connected to the three heating resistors 13 (13a, 13b, 13c) arranged in parallel as described above. Here, the three heat generating resistors 13 are connected to each other at the lower portions of the comb-tooth portions 14b and the individual electrodes 15 and connected to these energizing electrodes. Alternatively, each of the three heating resistors 13 may have a structure extending separately in a strip shape along the main scanning direction of the head substrate.

  In addition, a part of the comb-tooth portion 14b and the individual electrode 15 may each have a wide base end portion and may constitute a terminal that is electrically connected to the drive IC by, for example, a bonding wire.

  More specifically, a pair of comb teeth 14b of the common electrode 14 and an individual electrode 15 disposed between the pair of comb teeth 14b are defined by lead edges 14c and 15a to form two heat generating portions 16a and 16b. In this way, a heating element having a pair of heating parts 16 composed of two heating parts 16a and 16b is formed, and this heating element is formed on the support substrate 11 at a required dot density dpi in the main scanning direction of the thermal head. They are arranged in an array. In this case, one heating element prints 2 dots. The individual electrodes 15 of the respective heating elements are electrically connected to the drive IC by wire bonding and controlled to be energized. Here, as will be described in detail later, the base portion 14a of the common electrode 14 is disposed in the main scanning direction with a predetermined distance D from the pair of heat generating portions 16 as shown in FIG. .

  Next, the case where one heating element is composed of one heating part and prints one dot will be described with reference to FIG. Hereinafter, differences from the case described with reference to FIG. 1 will be mainly described.

  As shown in FIG. 2, the heating resistor 13 (13a, 13b, 13c) divided into three is defined by one comb tooth portion 14b of the common electrode 14 and one individual electrode 15 described above. A single heat generating portion 17 is formed. Here, one heating element is formed by the one comb-tooth portion 14 b, one individual electrode 15, and the single heating portion 17. The heating elements are arranged in an array at a required dpi in the main scanning direction of the thermal head on the support substrate 11, and the heating resistors 13 of the adjacent heating elements are separated. Also in this case, the three heating resistors 13 are connected to or separated from each other at the lower portion of the comb-tooth portion 14b and the individual electrode 15 in the same manner as described with reference to FIG.

  In the thermal head described with reference to FIGS. 1 and 2, a protective layer (not shown) is formed so as to cover the pair of heat generating portions 16 and the single heat generating portion 17 or the common electrode 14 and the individual electrodes 15 described above. The Here, the protective layer is not formed on the base end portion of the above-mentioned widened wire bonded.

  The support substrate 11 of the thermal head is usually a support substrate made of an insulating material having heat resistance, and is made of silicon, quartz, silicon carbide or the like in addition to alumina ceramics.

The glaze layer 12 is an insulating thin film made of an insulating material having an appropriate heat storage and heat dissipation action of heat generated by the heat generating portions 16 and 17 and having a surface smoothness. Examples of the glaze layer 12 include a SiO ₂ film (silicon oxide film), a SiON film (silicon oxynitride film), a SiN film (silicon nitride film), and the like. The glaze layer 12 may contain a small amount of additives such as metal fine particles that increase the thermal conductivity.

  The heating resistor 13 is composed of a cermet layer of an electrical resistor material such as TaSiO, NbSiO, TaSiNO, or TiSiCO. The common electrode 14 and the individual electrode 15 that are electrically connected to the heating resistor 13 are preferably as low as possible. For example, the main material is Al (aluminum), Cu (copper), an AlCu alloy, or the like. .

The protective layer is made of a hard and dense insulating material having thermal conductivity such as a SiO ₂ film, a SiN film, a SiON film, or a SiC film (silicon carbide film). Here, it is preferable that the outermost surface of the protective layer has a high wear resistance such as a TiN film (titanium nitride film). This protective layer covers the energizing electrodes and the heat generating portion of the heat generating element array, and has a function of protecting the recording medium from abrasion due to pressure contact or sliding contact, and corrosion due to contact with moisture contained in the atmosphere.

Next, an example of a method for manufacturing a thermal head having the structure of FIG. 1 will be described. First, an elongated support substrate 11 made of alumina and having a width of about several mm in the sub-scanning direction and a plate thickness of 0.5 mm to 1 mm is prepared. Then, a glass paste obtained by adding and mixing a suitable organic solvent and solvent to the glass powder of SiO ₂ is applied and formed by a known screen printing method. Then, by baking at a predetermined temperature, for example, a flat FG (Flat Glaze) structure glaze layer 12 having a film thickness of about 30 to 200 μm is formed.

A cermet layer such as a TaSiO ₂ film having a thickness of about 0.05 μm is formed by sputtering, for example, so as to cover the glaze layer 12. Subsequently, the heating resistor 13 is coated by sputtering to form an electrode film such as an Al film or an AlCu alloy film having a film thickness of about 0.5 μm to 1 μm. Then, the common electrode 14 and the individual electrode 15 that are to be energized electrodes of the heating element array are formed by patterning by manufacturing an etching mask by a photolithography technique and selective etching using the etching mask, that is, a photoengraving process. .

  Next, the cermet layer is etched by a photoengraving process using another etching mask, and the first heating resistor 13a, the second heating resistor 13b, and the third heating resistor 13c are formed by patterning. To do. In this way, the length of the pair of heat generating portions 16 in the sub-scanning direction is several tens to 300 μm, and the length in the main scanning direction (corresponding to the distance between the facing comb tooth portion 14b and the individual electrode 15) is 5. It is formed in a range of about 100 μm.

  In the formation of the pair of heating portions 16, first, a pattern of three heating resistors 13 each extending in a strip shape along the main scanning direction of the head substrate and separated by a cermet layer photoengraving process. To do. Thereafter, the common electrode 14 and the individual electrode 15 of the heating element array may be formed by patterning by a photoengraving process of the electrode film.

  Then, a protective layer covering the entire surface is formed by sputtering. Here, the protective layer is deposited to a thickness of about 2 μm to 5 μm, for example. In this way, the resistor substrate portion of the thermal head is formed.

  After that, the resistor substrate portion and the drive circuit substrate portion touched in the prior art in which, for example, a bare chip drive IC is incorporated in advance are placed on a heat dissipation substrate made of an aluminum plate or the like via an adhesive. Secure. Then, all the individual electrodes 15 of the heating element array are electrically connected to bonding pads on the output side of the driving IC with bonding wires made of, for example, Al wires or Au wires. Further, the bonding pad on the input side of the driving IC is electrically connected to the circuit pattern of the driving circuit board with a bonding wire. Finally, the driving IC and the bonding wire are hermetically sealed with a sealing material by a known mounting technique. In this way, a thermal head is completed.

  In the method of manufacturing the thermal head having the structure of FIG. 2, the heating resistor 13 is separated and patterned in the main scanning direction of the head substrate by etching the cermet layer in the photoengraving process described in the case of FIG. It is formed. And the single heat generating part 17 isolate | separated between adjacent heat generating elements is formed.

  In the image formation or overcoat process on the recording medium using the thermal head of the present embodiment, the thermal transfer ink ribbon or the like or the thermal recording medium (not shown) is used as the heating unit 16, as described in the prior art. 17 and a so-called platen roller (not shown) are nipped / slidably contacted and conveyed at a predetermined speed in the sub-scanning direction of the thermal head. In this clamping / sliding contact, the recording medium is heated by the heat generating portions 16 and 17 that generate heat by the energization pulse, and is printed or overcoated by the heat.

  The effects of the thermal head of this embodiment will be described.

  In the thermal head of this embodiment described in FIG. 1 or FIG. 2, the uneven shape on the surface of the protective layer reflects the wiring pattern of the common electrode 14 and the individual electrode 15 in the lower layer described in FIG. 1 or FIG. Will be. Short recesses and steps are formed along the wiring patterns of the comb teeth 14b and the individual electrodes 15 arranged in a comb-like shape in the sub-scanning direction, and the pattern in the main scanning direction on the base 14a of the common electrode 14 is formed. A stepped portion is formed. However, the step portion along the main scanning direction is interrupted by the comb tooth portion 14b extending from the base portion 14a in the sub-scanning direction, and unlike the case of the protective layer 106 in the prior art described with reference to FIG. It does not extend in the main scanning direction.

  In this embodiment, since the common electrode 14 and the individual electrode 15 in the thermal head are configured in the wiring pattern as described above, it is easy to form a residue generated from an ink ribbon, a thermal recording medium, or the like as described in the related art. To be suppressed. For example, in the case of image formation or overcoat processing on a recording medium using an ink ribbon, the lubricant of the ink ribbon heated by the heat generating portions 16 and 17 adheres to the step portions along the comb tooth portions 14b and the individual electrodes 15 described above. To do. However, these deposits are scraped off along the downstream side where the recording medium is conveyed by sliding contact in the sub-scanning direction with the platen roller. Further, the step portion of the common electrode 14 along the main scanning direction is separated from the heat generating portions 16 and 17 and is interrupted by the comb tooth portion 14b extending from the base portion 14a in the sub-scanning direction. Residue that accumulates in water is reduced.

  In the operation of the thermal head described with reference to FIGS. 1 and 2, the heat generating portion 16 or 17 is divided into three parts in the sub-scanning direction, so that compared with the conventional thermal head described with reference to FIG. Thus, the peak temperature is reduced, and the temperature distribution of the heat generating part is easily flattened. This will be described with reference to FIG. FIG. 3 is a temperature distribution diagram for explaining the heat generation characteristics of the heat generating portion in the present embodiment. For comparison, the temperature distribution in the prior art is also shown. Here, in the case of the present embodiment, the thermal head has the structure described with reference to FIG. 1, and the heating portions 16 are arranged at 300 dpi in the main scanning direction of the head substrate in the thermal head. In the case of the prior art, it has the structure described with reference to FIG. 5 and is similarly arranged at 300 dpi in the main scanning direction.

In the thermal head of the present embodiment, the length of each of the heat generating portions 16a and 16b in the main scanning direction (corresponding to the distance between the facing comb tooth portion 14b and the individual electrode 15) is set to 34 μm, and its sub-scanning direction The length of was set to 150 μm. Further, the pattern width of the comb-tooth portion 14b and the individual electrode 15 was set to a little over 8 μm so that the pitch of one heating element was about 84.7 μm. Here, the lengths of the first heating resistor 13a and the third heating resistor 13c in the sub-scanning direction are both 53.6 μm, that of the second heating resistor 13b in the center is the smallest 21.5 μm, and the first space _{S 1} and the second space _{S 2} were both set to 10.7.

  Thus, the space provided in the heating resistor becomes a non-heating portion. Therefore, in this structure, the width of the electrode lead edge can be made larger than that of the heating resistor, so that the heat generation distribution can be easily adjusted by selecting the width, number, and position of the space. In the present embodiment, the space is arranged such that the length of the second heat generating resistor 13b at the center is smaller than that of both sides with respect to the length of the heat generating resistor in the transport direction. In addition, this space can also be made into a diagonal pattern or a curvilinear pattern in the conveyance direction.

  In the conventional thermal head, the length of the heat generating portion 105 and its energizing electrode in the main scanning direction is set to 35 μm, and the space in the main scanning direction is set to a little over 7 μm. Further, the length of the heat generating portion 105 in the sub-scanning direction was 150 μm. The other components of the thermal head are designed to be the same in the case of the present embodiment and the case of the prior art.

  In FIG. 3, the horizontal axis represents the position in the length direction (sub-scanning direction) of the heat generating portion, and the vertical axis represents the temperature on the center line of the heat generating portion. And the temperature distribution of the heat generating part is shown as a simulation result. This temperature distribution is close to the actual measurement. As shown by the solid line in FIG. 3, the peak temperature is lowered and the temperature difference in the heat generating region is reduced and the temperature distribution is easily uniformed compared to the prior art shown by the dotted line in FIG. I understand.

  In this way, the temperature distribution of the heat generating portion of the present embodiment is flattened, so that overheating of the ink ribbon or the thermal recording medium can be suppressed. And generation | occurrence | production of the residue which consists of them, for example from a lubricant comes to reduce.

  As described above, the base portion 14a of the common electrode 14 is disposed in the main scanning direction with a predetermined distance D from the heat generating portions 16 and 17 of the thermal head. That is, unlike the prior art, the step portion of the protective layer that is interrupted in the main scanning direction and formed corresponding to the base portion 14a as described above is located away from the heat generating portion. This also reduces the formation of residue on the step. Here, depending on the printing apparatus on which the thermal head is mounted, the required temperature of the heat generating part may be as high as about 500 ° C., for example. When the heat generation temperature becomes high in this way, the formation of residues on the stepped portion cannot be ignored. However, if the separation distance D is 20 μm or more, the influence of the heat generation is completely eliminated.

  In the present embodiment, electrodes for energizing the heat generating part of the thermal head are arranged extending in a comb shape in the recording medium conveyance direction. The heat generating resistor of each heat generating part is divided into, for example, three parts in the transport direction, and the current distribution in the direction intersecting the transport direction is energized to reduce the peak temperature of the heat generating part so that the temperature distribution is easily flattened. It has become. For this reason, in the operation of the thermal head, for example, a residue generated by heating an ink ribbon or a thermal recording medium on the surface of the protective layer covering the heating portion of the resistor substrate portion can be easily suppressed. Further, there is no separation peeling sound or sliding contact sound during operation of the printing apparatus as described in the prior art, and noise reduction during operation is facilitated.

  In addition, the pattern width of the comb-like common electrode and individual electrode for energizing the heat generating part can be made narrower than in the conventional case, so that the heat released from the heat generating part through the energizing electrode is reduced. become.

  And in the thermal head of this embodiment, the peak temperature of the center part of the heat generating part of the thermal head is lowered, the temperature distribution is flattened, and overheating is suppressed. For these reasons, the power consumption is reduced as compared with the conventional thermal head.

  Although the preferred embodiments of the present invention have been described above, the above-described embodiments do not limit the present invention. Those skilled in the art can make various modifications and changes in specific embodiments without departing from the technical idea and technical scope of the present invention.

  In the above-described thermal head, the case where the glaze layer 12 has the FG structure is described. The glaze layer 12 may have a so-called PEG structure in which a part thereof is formed by partial etching (PE) and has a raised portion. Or, conversely, there may be a PG structure formed without a flat portion and raised in a strip shape in the main scanning direction of the thermal head.

  Further, the heating resistor 13 may be divided into two in the sub-scanning direction, or may have a structure of a plurality of divisions exceeding three divisions.

  Further, the comb-tooth portion 14b and the individual electrode 15 of the common electrode 14 of the thermal head have a plurality of electrodes arranged side by side in a comb-teeth shape obliquely with respect to the extending direction of the heating resistor 13, thereby forming an array of heating elements. The structure may be arranged.

  In this embodiment, the comb teeth 14b and the individual electrodes 15 of the common electrode 14 are formed on the heating resistor 13, but conversely, the heating resistors 13 are formed above the comb teeth 14b and the individual electrodes 15. A thermal head having a formed structure may be used.

  In the present invention, the resistor substrate portion on which the heat generating portion of the thermal head is provided, and the drive circuit substrate portion on which the drive IC for driving the heat generating portion is mounted are integrally formed on one head substrate. The same applies to the case of a thermal head.

DESCRIPTION OF SYMBOLS 11 ... Support substrate, 12 ... Glaze layer, 13 ... Heat generating resistor, 13a ... 1st heat generating resistor, 13b ... 2nd heat generating resistor, 13c ... 3rd heat generating resistor, 14 ... Common electrode, 14a ... base, 14b ... comb-tooth portion, 15 ... individual electrode, 16 ... a pair of the heat generating portion, 17 ... single heat generating portion, the distance between the base and the heat generating portion of the D ... common electrode, S 1 _... first space, S ₂ ... 2nd space

Claims (1)

A heat-retaining layer on a support substrate; a heat-generating part formed of a thin-film heating resistor formed on the heat-retaining layer; an electrode for energizing the heat-generating part; and a protective layer covering the heat-generating part. A thermal head used in a printing apparatus for performing a printing process or an overcoat process after the printing process,
The electrodes are arranged to extend in a comb-tooth shape in the conveyance direction of the recording medium, and the electrodes are formed from a base portion extending in one direction of the support substrate and a comb-tooth portion extending from the base portion in a comb-tooth shape. Consisting of a common electrode and an individual electrode whose one end portion enters between the comb teeth portions,
The heating resistor of the heat generating part is disposed between the lead edges of the common electrode and the individual electrode, and has a pattern longer in the transport direction than the distance between the lead edges of the electrodes , leaving a space in the transport direction. 3 is divided split above, the center portion of the divided heating resistors has become shortest in the transport direction, and characterized in that it is energized in a direction intersecting the conveying direction Te Thermal head.

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