JP2011161730A - Thermal print head, and thermal printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a feeling of glossiness, or to smooth the tone of an output print and image. <P>SOLUTION: A heating element plate of thermal print head includes an insulating substrate 36, a plurality of heating resistor part 40, conductive parts 44, 46, the first protective layer, a thermal diffusion part 52, and the second protective layer. The heating resistor part 40 is laminated on the insulating substrates 34, 36 and extends in the sub-scanning direction 92 where a recording medium travels. The conductive parts 44, 46 are electrically connected with the end of each heating resistor part 40 and apply a voltage in the sub-scanning direction 92 of each heating resistor parts 40. The first protective layer consists of an insulation and is laminated on the heating resistor part 40 so as to cover the heating resistor part 40. The thermal diffusion part 52 is formed on the first protective layer in the shape of a strip and extends meanderingly in the main scanning direction 91 in a heating region 32 across the upper part of a plurality of sets of heating resistor part 40 which output a plurality of pixels. The second protective layer is laminated on the thermal diffusion part 52. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  The thermal print head is an output device that heats a plurality of heat generating resistors arranged in a heat generating area, and prints and prints characters, figures, and the like on a recording medium by the heat. This thermal print head is widely used in recording devices such as a barcode printer, a digital plate making machine, a photo printer, an imager, and a seal printer.

  A conventional thermal print head will be described with reference to FIGS. FIG. 7 is a view for explaining a conventional thermal print head, and is a partial top view of a heating plate in which the first protective layer and the second protective layer are omitted. 8 is a cross-sectional view taken along arrow VIII-VIII in FIG.

  The thermal print head includes a heat radiating plate, a heating element plate 130 disposed on the same surface of the heat radiating plate, and a circuit board. The heating element plate 130 includes a support substrate 134, a glaze layer 136, a plurality of heating resistance portions 140, conductive portions 144, 146, a first protection layer 150a, a plurality of heat diffusion portions 152, and a second protection layer 150b. ing.

  The plurality of heating resistor portions 140 are formed on the glaze layer 136, extend in the sub-scanning direction 92, and are arranged at intervals in the main scanning direction 91. Conductive portions (electrodes) 144 and 146 are formed at both ends of each heat generating resistor portion 140. When a voltage is applied between the conductive portions 144 and 146, each heat generating resistor portion 140 generates heat. Each heat generating resistor part 140 serves as a heat generating element. As shown in FIG. 7, a belt-like region in which a plurality of heat generating resistor parts 140 are arranged becomes a heat generating region 132.

  In FIG. 7, the conductive portion 146 is a folded electrode, and two adjacent heating resistor portions 140 are connected in series. For this reason, the pair of heating resistor portions 140 connected by the conductive portion 146 generate heat simultaneously by the voltage applied between the conductive portions 144, and output one pixel to the recording medium (one pixel two element type).

  The first protective layer 150a is laminated so as to cover the exposed surfaces of the heat generating resistor portion 140 and the conductive portions 144 and 146, and serves to insulate the heat generating resistor portion 140 and the conductive portions 144 and 146 from the heat diffusion portion 152. Fulfill. The thermal diffusion part 152 is formed on the first protective layer 150a and above the heating resistor part 140 of each set that outputs one pixel. Further, the second protective layer 150b is laminated so as to cover the exposed surfaces of the first protective layer 150a and the thermal diffusion unit 152, and from the friction with the recording medium when the thermal printer is used, the heating resistor unit 140 and the like. (For example, refer to Patent Document 1).

  On the other hand, an electrical component such as a driving IC serving as a driving circuit for supplying power to the heating resistor 140 is mounted on the circuit board.

  Here, a thermal printer using the above-described thermal print head will be described. The thermal printer generally includes a platen roller, and the platen roller is disposed so that the side surface thereof is in contact with the heat generating region 132 with the main scanning direction 91 as an axis, and is rotatable about the axis. Is provided.

  For example, the sublimation thermal printer rotates the platen roller to press the recording medium and the ink ribbon inserted between the platen roller and the heat generating area 132 against the heat generating area 132 while sub-scanning the recording medium and the ink ribbon. Move in direction 92. By changing the heat generation pattern of the heat generating area 132 as the recording medium moves, the sublimation dye ink applied to the ink ribbon is heated and sublimated, transferred onto the recording medium, and printed on the recording medium. Print.

  As described above, when a voltage is applied between the conductive portions 144 and 146, the heating resistor portion 140 generates heat. However, a part of the heat generated from the end of the heating resistor portion 140 in the sub-scanning direction 92 is thermally conductive. It escapes to the high conductive parts 144,146. For this reason, in a thermal print head in which the thermal diffusion unit 152 is not provided, the temperature at the end of the heat generating area 132 in the sub-scanning direction 92 is extremely lower than the temperature at the center, and the printing / printing quality is degraded. End up. In order to prevent this, if the applied voltage is increased to increase the amount of heat generation, the temperature of the central portion of the heat generating area 132 in the sub-scanning direction 92 becomes too high, and the ink ribbon is baked or the like. It will decline.

  On the other hand, in the thermal print head provided with the thermal diffusion part 152 as described above, the heat generated from the center part in the sub-scanning direction 92 of the heat generation area 132 is sub-scanned in the heat generation area 132 via the heat diffusion part 152. To the end of direction 92. Therefore, the temperature distribution in the sub-scanning direction of the heat generating region 132 is flattened.

JP 2006-205520 A

  The above-described thermal print head has a plurality of thermal diffusion portions 152 in order to flatten the temperature distribution in the sub-scanning direction 92 of the heat generating area 132. The plurality of thermal diffusion portions 152 are formed above each pair of heating resistor portions 140 that output one pixel, and are not formed above the gap 142 between each adjacent heating resistor portion 140. . Therefore, although the amount of heat generation is large above the heating resistor portions 140 of each group, the amount of heat generation is small above the gap 142 between the heating resistor portions 140 of each group.

  Here, in the thermal transfer type thermal printer (thermal melting type printer and sublimation type printer), in order to improve the durability of the recording medium, after the ink is transferred onto the recording medium, the heat generated by the heating resistor 140 is used. In some cases, an overcoat (protective layer) is transferred onto a recording medium. When the above-described thermal print head is used to transfer the overcoat, the overcoat is transferred onto the recording medium corresponding to the position of each heating resistor 140 that outputs one pixel. The overcoat is not transferred onto the recording medium corresponding to the position of the air gap 142 between the heat generation resistor portions 140, and the unevenness of the overcoat layer is formed on the surface of the recording medium. As a result, light was irregularly reflected by the unevenness of the overcoat layer, and glossiness was difficult to be obtained.

  Further, when the above-described thermal print head is employed in a thermal printer, the recording medium corresponding to the position of each heating resistor 140 that outputs one pixel is heated, but between each heating resistor 140 of each set. The recording medium corresponding to the position of the gap 142 is not heat sensitive. Therefore, when the output printing / printing is observed, the boundary between adjacent pixels can be visually recognized, that is, it is difficult to realize smooth gradation (gradation). Such a problem occurs even when the above-described thermal print head is employed in a sublimation thermal printer.

  SUMMARY An advantage of some aspects of the invention is to improve the glossiness or smooth the gradation of the output printing / printing.

  In order to achieve the above object, a thermal print head according to the present invention is formed on an insulating substrate and the insulating substrate, extends in the sub-scanning direction in which the recording medium travels, and is orthogonal to the sub-scanning direction. A plurality of heat generating resistor portions that are arranged side by side in the main scanning direction and output a plurality of pixels, and are electrically connected to both ends of the plurality of heat generating resistor portions, and sub-scanning the heat generating resistor portions. A conductive portion that applies a voltage in a direction, a first protective layer that is formed of an insulating material and covers the insulating substrate, the heating resistor portion, and an exposed surface of the conductive portion, and extends in a main scanning direction, And a thermal diffusion part formed on the first protective layer so as to straddle the plurality of heating resistor parts outputting a plurality of pixels.

  In order to achieve the above object, a thermal printer according to the present invention includes an insulating substrate and a sub-scanning direction formed on the insulating substrate and extending in a sub-scanning direction in which the recording medium travels, and orthogonal to each other. Are arranged side by side in the main scanning direction, and are electrically connected to both ends of the plurality of heating resistor units and the plurality of heating resistor units for outputting a plurality of pixels. A conductive portion that applies a voltage in the scanning direction; a first protective layer that is made of an insulating material and that covers the insulating substrate, the heating resistor portion, and an exposed surface of the conductive portion; and extends in the main scanning direction. And a thermal print head having a thermal diffusion part formed on the first protective layer so as to straddle the plurality of heating resistor parts for outputting a plurality of pixels.

  According to the present invention, it is possible to improve the glossiness or to smooth the gradation of the output printing / printing.

1 is a perspective view of a thermal print head according to a first embodiment of the present invention. 1 is a partial cross-sectional view of a thermal printer according to a first embodiment of the present invention. It is a figure for demonstrating the thermal print head which concerns on the 1st Embodiment of this invention, Comprising: It is a partial top view of the heat generating body board which abbreviate | omitted the 1st protective layer and the 2nd protective layer. FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 3. It is a figure for demonstrating the thermal print head concerning the 2nd Embodiment of this invention, Comprising: It is the partial top view of the heat generating body board which abbreviate | omitted the 1st protective layer and the 2nd protective layer. It is a figure for demonstrating the thermal print head which concerns on the 3rd Embodiment of this invention, Comprising: It is the partial top view of the heat generating body board which abbreviate | omitted the 1st protective layer and the 2nd protective layer. It is a figure for demonstrating the conventional thermal print head, Comprising: It is a partial top view of the heat generating body board which abbreviate | omitted the 1st protective layer and the 2nd protective layer. FIG. 8 is a sectional view taken along arrow VIII-VIII in FIG. 7.

[First Embodiment]
A thermal print head and a thermal printer according to a first embodiment of the present invention will be described.

  First, an outline of the thermal print head 10 and the thermal printer according to the first embodiment will be described with reference to FIGS. 1 and 2. FIG. 1 is a perspective view of a thermal print head. FIG. 2 is a partial cross-sectional view of the thermal printer.

  The thermal print head 10 includes a heat radiating plate 20, a heating element plate 30, and a circuit board 60. The heat generating plate 30 and the circuit board 60 are placed on the same surface of the heat radiating plate 20.

  The heat radiating plate 20 is made of a metal such as aluminum and extends in the main scanning direction 91 and plays a role of releasing heat from the heat generating plate 30 to the outside of the thermal print head 10.

  The heat generating plate 30 is placed on the heat radiating plate 20 and extends in the main scanning direction 91. A heat generating region 32 extending in the main scanning direction 91 is formed on the heat generating plate 30.

  The circuit board 60 is placed on the heat sink 20 and extends in the main scanning direction 91 in parallel with the heat generating plate 30. On the circuit board 60, a driving IC 62 and connectors 64a and 64b are mounted. The driving IC 62 serves as a driving circuit that generates heat in the heat generating region 32. Control signals and drive power for forming a predetermined heat generation pattern in the heat generation region 32 are input via the connectors 64a and 64b.

  The wiring pattern formed on the heating plate 30 and the driving IC 62 are electrically connected by, for example, bonding wires 66a. Further, the wiring pattern formed on the circuit board 60 and the driving IC 62 are electrically connected by, for example, bonding wires 66b. The driving IC 62 and the bonding wires 66a and 66b are sealed with a sealing material 68 made of resin.

  The thermal printer according to the present embodiment is, for example, a sublimation type thermal printer. The sublimation type thermal printer heats and sublimates the sublimation dye ink applied to the ink ribbon 74 in the heat generating area 32, transfers the ink to a predetermined recording medium 72 such as coated paper, and prints on the recording medium 72. Print.

  The thermal printer has a platen roller 70 made of a material having a predetermined elasticity and formed in a cylindrical shape. The platen roller 70 is provided so as to be rotatable about the axis 70a with the main scanning direction 91 as an axis 70a. The platen roller 70 is disposed such that its side surface 70 b is in contact with the heat generating region 32.

  When the thermal printer is used, the recording medium 72 and the ink ribbon 74 are inserted between the platen roller 70 and the heat generating area 32. The thermal printer rotates the platen roller 72 to move the recording medium 72 and the ink ribbon 74 in the sub-scanning direction 92 perpendicular to the main scanning direction 91 while pressing the ink ribbon 74 against the heat generating area 32. The thermal printer changes the heat generation pattern of the heat generating area 32 as the recording medium 72 moves, thereby forming a desired character / image on the recording medium 72.

  Next, details of the heating element plate 30 of the thermal print head 10 according to the present embodiment will be described with reference to FIGS. 3 and 4. FIG. 3 is a partial top view of the heating element plate in which the first protective layer and the second protective layer are omitted. 4 is a cross-sectional view taken along the line IV-IV in FIG.

  The heating element plate 30 includes an insulating substrate, a resistor layer (heating resistor portion 40), a conductor layer (conductive portions 44 and 46), a first protective layer 50a, a heat diffusion portion 52, and a second protective layer 50b. is doing. The insulating substrate is formed by laminating a glaze layer 36 on the surface of a support substrate 34 made of an insulator such as alumina.

  A resistor layer is laminated on the glaze layer 36 of the insulating substrate, and the resistor layer forms a plurality of heating resistor portions 40.

  The plurality of heating resistor portions 40 each extend linearly with a constant width in the sub-scanning direction 92 and are arranged with an interval (gap 42) therebetween in the main scanning direction 91. The heat generating region 32 refers to a band-shaped region in which a plurality of heat generating resistor portions 40 are arranged.

  A conductor layer is laminated on the resistor layer, and the conductor layer forms a plurality of electrodes (conductive portions) 44 and 46.

  An individual electrode (conductive portion) 44 is formed and electrically connected to the end of each heating resistor 40 on the upstream side in the sub-scanning direction 92 (the supply side of the recording medium 72). Further, the end portions of the two adjacent heating resistor portions 40 on the downstream side in the sub-scanning direction 92 (the discharge side of the recording medium 72) are electrically connected in series by a folded electrode (conductive portion) 46.

  The individual electrode 44 and the folded electrode 46 are made of, for example, aluminum and are formed to have a thickness of 0.7 μm, for example. As described above, the individual electrode 44 is connected to the driving IC 62 via the bonding wire 66, for example.

  Each heating resistance portion 40 serves as a heating element, and a set of heating resistance portions 40 connected in series by the folded electrode 46 simultaneously generates heat due to a voltage applied between the individual electrodes 44, and the recording medium One pixel is output to 72 (one pixel two-element type).

The first protective layer 50 a is laminated so as to cover the exposed surfaces of the plurality of heating resistor portions 40, the conductive portions 44 and 46, and the glaze layer 36. The first protective layer 50 a is made of, for example, a material mainly composed of SiO ₂ , SiAlON, or SiON, and serves to insulate the heat generating resistor portion 40 and the conductive portions 44 and 46 from the heat diffusion portion 52. The first protective layer 50a is formed with a thickness of 3.0 μm, for example.

  The thermal diffusion portion 52 is formed in a strip shape on the first protective layer 50a so as to straddle the plurality of heating resistor portions 40 that output a plurality of pixels, and meanders the heating region 32 in the main scanning direction 91. It extends. The thermal diffusion part 52 is made of, for example, a high heat conductive material such as metal (Al, Cu, etc.) or an alloy, and is formed to a thickness of 1.0 μm. The thermal diffusion unit 52 plays a role of diffusing the heat generated from the heating resistor unit 40 in the plane direction.

  The thermal diffusion unit 52 includes a plurality of main parts 52a and a connecting part 52b that connects adjacent main parts 52a. Each main portion 52a is formed in an S shape above each pair of heating resistor portions 40 connected by the folded electrode 46, and is above the center portion and end portions of the heating resistor portions 40 in the sub-scanning direction 92. It is formed so as to pass above.

  On the other hand, the connecting portion 52b extends in the main scanning direction 91 above the gap 42 between the heating resistor portions 40 of each set, and is formed with a constant width. The area of each connecting portion is preferably formed to be ¼ or less of the area of the gap 42 between the heating resistor portions 40 of each set.

  The second protective layer 50b is made of, for example, the same material as that of the first protective layer 50a, and is laminated so as to cover the heat diffusion portion 52 and the exposed surface of the first protective layer 50a. The second protective layer 50b serves to protect the heating resistor 40, the conductive parts 44 and 46, and the thermal diffusion part 52 from friction with the recording medium 72 when the thermal printer is used. The second protective layer 50b is formed with a thickness of 5.0 μm, for example.

  Next, an example of a method for forming the heating element plate 30 will be described.

  First, a support substrate 34 made of ceramic is formed, and a glaze layer 36 made of glass is fused to the surface thereof.

  Next, a resistor layer and a conductor layer are sequentially laminated on the entire surface of the glaze layer 36 by a thin film forming apparatus such as a sputtering apparatus. Then, after the conductor layer is formed in the shape of the conductive portions 44 and 46 by the photoengraving process, the resistor layer is formed in the shape of the heating resistor portion 40.

  Next, the first protective layer 50 a is formed so as to cover the exposed surfaces of the plurality of heating resistor portions 40, the conductive portions 44 and 46, and the glaze layer 36. And after laminating | stacking a thermal-diffusion layer with a thin film formation apparatus, after forming a thermal-diffusion layer in the shape of the thermal-diffusion part 52 by the photoengraving process, the exposed surface of the thermal-diffusion part 52 and the 1st protective layer 50a The second protective layer 50b is formed so as to cover the surface.

  Further, an opening is formed on the surface of the portion of the individual electrode 44 connected to the bonding wire 66a by a photo-engraving process.

  The effects of the thermal print head 10 and the thermal printer according to the present embodiment will be described.

  According to the present embodiment, the heat diffusing section 52 extends in the main scanning direction 91 across the heat generating area 32 across the plurality of sets of heat generating resistance sections 40 that output a plurality of pixels. Therefore, not only the temperature above the heating resistor portions 40 of each set that outputs one pixel, but also the temperature above the gap 42 between the heating resistor portions 40 of each set rises, and the second protection in the main scanning direction 91 is performed. The surface temperature distribution of the layer 50b is flattened.

  Here, when the thermal print head 10 according to the present embodiment is employed in a thermal transfer type thermal printer (a thermal melting type printer and a sublimation type printer) and the overcoat is transferred onto the recording medium 72, each set of the heating resistor units 40. The overcoat is transferred not only on the recording medium 72 corresponding to this position but also on the recording medium 72 corresponding to the position of the gap 42 between the heating resistor portions 40 of each set. Therefore, the unevenness of the overcoat layer formed on the surface of the recording medium 72 is reduced, and as a result, irregular reflection of light is reduced and glossiness is improved.

  Further, when the thermal print head 10 according to the present embodiment is employed in a thermal thermal printer, not only on the recording medium (thermal paper) 72 corresponding to the position of each set of the heating resistor units 40 outputting one pixel, Heat is also sensed on the recording medium 72 corresponding to the position of the gap 42 between the pair of heating resistor portions 40. As a result, the gradation of the output print / print becomes smooth. This effect can be obtained even if the thermal print head 10 according to the present embodiment is employed in a sublimation thermal printer.

  As the area of the connecting portion 52b increases, the boundary between adjacent pixels is less likely to occur, and the gradation becomes smoother. However, the heat from the heating resistor portion 40 is excessively diffused in the plane direction, and printing / printing is performed. It does not contribute and color development efficiency is reduced. Further, the output print / print is blurred, and the print / print quality is deteriorated. Considering this point, it is desirable that the area of the connecting portion 52b is formed to be ¼ or less of the area of the gap 42 between the heating resistor portions 40 of each set.

  Further, since the heat diffusion part 52 is formed so as to pass above the center part of the heating resistor part 40 in the sub-scanning direction 92 and above the end part, the center part of the heating resistor part 40 in the sub-scanning direction 92 is formed. The heat from the heat is transmitted to the end, and the temperature distribution in the sub-scanning direction 92 of the heat generating region 32 is flattened. As a result, it is possible to suppress the printing of the recording medium 72 and improve the printing / printing quality.

  Furthermore, since the thermal diffusion part 52 is formed in a band shape, the adhesion area between the first protective layer 50a and the second protective layer 50b increases, and the second protective layer 50b is unlikely to peel off. In addition, when the 1st protective layer 50a and the 2nd protective layer 50b are comprised with the same material, the adhesive force of the 1st protective layer 50a and the 2nd protective layer 50b will improve, and it is more effective.

[Second Embodiment]
A thermal print head according to a second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a diagram for explaining the thermal print head according to the present embodiment, and is a partial top view of the heating element plate from which the first protective layer and the second protective layer are omitted. In addition, this embodiment is a modification of 1st Embodiment, Comprising: The same code | symbol is attached | subjected to the same part or similar part as 1st Embodiment, and duplication description is abbreviate | omitted.

  In the present embodiment, each main portion 52a of the thermal diffusion portion 52 is formed in an X shape above each set of heating resistor portions 40 that output one pixel, and the sub-scanning direction of the heating resistor portion 40 It is formed so as to pass above the center part of 92 and above the end part. Also according to this embodiment, the same effect as that of the first embodiment can be obtained.

[Third Embodiment]
A thermal print head according to a third embodiment of the present invention will be described with reference to FIG. FIG. 6 is a diagram for explaining the thermal print head according to the present embodiment, and is a partial top view of the heating element plate from which the first protective layer and the second protective layer are omitted. In addition, this embodiment is a modification of 1st Embodiment, Comprising: The same code | symbol is attached | subjected to the same part or similar part as 1st Embodiment, and duplication description is abbreviate | omitted.

  In the present embodiment, an individual electrode (conductive portion) 44 is formed at one end of each heating resistor section 40 in the sub-scanning direction 92, and the other end of each heating resistor section 40 in the sub-scanning direction 92 is A common electrode (conductive portion) 48 is formed. Each heating resistor section 40 generates heat by a voltage applied between the individual electrode 44 and the common electrode 48 and outputs one pixel to the recording medium 72 (one pixel one element type).

  In the present embodiment, each main portion 52a of the thermal diffusion portion 52 is formed in an S shape above each heating resistor portion 40, and above the central portion of each heating resistor portion 40 in the sub-scanning direction 92 and It is formed so as to pass over the end. Also according to this embodiment, the same effect as that of the first embodiment can be obtained.

[Other Embodiments]
In the first to third embodiments, the flat glaze layer 36 is employed, but a convex glaze layer that rises along the heat generating region 32 may be employed.

In the first embodiment, the same material is used for the first protective layer 50a and the second protective layer 50b. For example, the second protective layer 50b has wear resistance such as SiAlON or Ta ₂ O _5. A functional material may be used.

  Further, in the 1-pixel 1-element type thermal print head 10 by combining the second embodiment and the third embodiment, each main portion 52 a of the thermal diffusion portion 52 is placed above each heating resistor portion X. It may be formed in a letter shape.

DESCRIPTION OF SYMBOLS 10 ... Thermal print head, 20 ... Heat sink, 30 ... Heat generating body plate, 32 ... Heat generating area, 34 ... Support substrate, 36 ... Glaze layer, 40 ... Heat generating resistor part, 42 ... Air gap between heat generating resistor parts, 44 ... Individual Electrode (conductive part), 46 ... folded electrode (conductive part), 48 ... common electrode (conductive part), 50a ... first protective layer, 50b ... second protective layer, 52 ... heat diffusion part, 52a ... heat diffusion part Main part, 52b ... Connection part of heat diffusion part, 60 ... Circuit board, 62 ... Driving IC, 64a, 64b ... Connector, 66a, 66b ... Bonding wire, 68 ... Sealing material, 70 ... Platen roller, 70a ... Platen Roller shaft, 70b ... side surface of platen roller, 72 ... recording medium, 74 ... ink ribbon, 91 ... main scanning direction, 92 ... sub-scanning direction

Claims (14)

An insulating substrate;
A plurality of heat generation elements that are formed on the insulating substrate, extend in the sub-scanning direction in which the recording medium travels, and are arranged side by side in the main scanning direction orthogonal to the sub-scanning direction to output a plurality of pixels. A resistance section;
A conductive portion that is electrically connected to both ends of the plurality of heating resistor portions and applies a voltage in a sub-scanning direction of the heating resistor portion;
A first protective layer made of an insulating material and formed so as to cover an exposed surface of the insulating substrate, the heating resistor portion and the conductive portion;
A thermal diffusion part formed on the first protection layer so as to extend in the main scanning direction and straddle over the plurality of heating resistor parts outputting a plurality of pixels;
A thermal print head comprising:   The heat diffusing section is formed so as to pass above a central portion in the sub-scanning direction of each of the heating resistor sections that output each pixel and above an end portion of each of the heating resistor sections in the sub-scanning direction. The thermal print head according to claim 1.   3. The thermal print head according to claim 1, wherein the thermal diffusion portion is formed in a belt shape and extends in a meandering manner in the main scanning direction.   4. The thermal print head according to claim 1, wherein the thermal diffusion portion is formed in an S shape above each of the heating resistor portions that output each pixel. 5.   3. The thermal print head according to claim 1, wherein the thermal diffusion portion is formed in an X shape above each of the heat generating resistor portions that output each pixel. 4.   The thermal print head according to claim 1, wherein the thermal diffusion portion is made of a metal material.   The thermal print head according to claim 1, further comprising a second protective layer made of an insulating material and formed to cover the first protective layer and the thermal diffusion portion.   The thermal print head according to claim 7, wherein the first protective layer and the second protective layer are made of the same insulating material.   An insulating substrate and an insulating substrate formed on the insulating substrate, extending in the sub-scanning direction in which the recording medium travels, arranged in a row in the main scanning direction perpendicular to the sub-scanning direction, and outputting a plurality of pixels A plurality of heat generating resistor portions, a conductive portion that is electrically connected to both ends of the plurality of heat generating resistor portions and applies a voltage in a sub-scanning direction of the heat generating resistor portions, and an insulating material. A first protective layer formed so as to cover the exposed surface of the heating resistor portion and the conductive portion, and extending in the main scanning direction so as to straddle over the plurality of heating resistor portions outputting a plurality of pixels. A thermal printer comprising a thermal print head having a thermal diffusion portion formed on a first protective layer.   The thermal printer according to claim 9, wherein the thermal printer is a thermal transfer thermal printer capable of transferring an overcoat onto the recording medium.   The thermal printer according to claim 9, wherein the thermal printer is a sublimation type thermal printer.   The thermal printer according to claim 9, wherein the thermal printer is a thermal printer.   The heat diffusing section is formed so as to pass above a central portion in the sub-scanning direction of each of the heating resistor sections that output each pixel and above an end portion of each of the heating resistor sections in the sub-scanning direction. The thermal printer according to any one of claims 9 to 12.   The thermal printer according to any one of claims 9 to 13, wherein the thermal diffusion unit is formed in a belt shape, meandering and extending in the main scanning direction.

Images