JP2011073270A - Thermal print head and thermal printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make the temperature distribution of a heating region flat in a thermal print head. <P>SOLUTION: The thermal print head 10 is made by way of forming a heating resistance part 41 and electrodes (electric conduction part) 51, 54 on an insulating substrate. The heating resistance part 41 extends in the sub-scanning direction and is formed with constant width in the main scanning direction. The electrodes 51, 54 are connected to the ends 42, 43 of the heating resistance part 41 and applies a voltage. The ends 42, 43 of the heating resistance part 41 are branched into the first ends 42a, 43a and the second ends 42b, 43b by notches 46, 47. The connecting part of the electrodes 51, 54 is branched into the first connecting parts 52a, 55a connected to the first ends 42a, 43a and the second connecting parts 52b, 55b connected to the second ends 42b, 43b by slits 53, 56. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  A conventional thermal print head will be described with reference to FIG. FIG. 8 is a diagram for explaining a conventional thermal print head, and is a schematic diagram showing a temperature distribution in the sub-scanning direction on the surface of the protective film, together with a schematic top view of the heating element plate. The top view of the heating element plate shown in FIG. 8 is a diagram with the protective film disposed on the outermost surface removed.

  A thermal print head is an output device that heats a plurality of resistors arranged in a heat generating area and forms images such as characters and figures on a heat-sensitive recording medium such as heat-sensitive recording paper by the heat (for example, Patent Documents). 1). 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.

  The thermal print head includes a heat radiating plate, and a heat generating plate and a circuit board disposed on the same surface of the heat radiating plate.

  A resistor layer is formed on the surface of the glaze layer of the insulating substrate. The resistor layer has a plurality of heating resistor portions 141. The plurality of heating resistor portions 141 each linearly extend with a certain width in the sub-scanning direction 92 and are arranged side by side in the main scanning direction 91 at intervals. Each heating resistor 141 has a rectangular shape extending in the sub-scanning direction 92. The heat generating region 132 refers to a band-shaped region in which a plurality of heat generating resistance portions 141 are arranged.

  An individual electrode (conductive portion) 151 is formed at one end 142 of each heat generating resistor portion 141, and a common electrode (conductive portion) 154 is formed at the other end 143 of each heat generating resistor portion 141. The individual electrode 151 and the common electrode 154 are connected to the driving IC. Each heating resistor 141 plays a role as one heating element, and outputs one dot to the thermal recording medium (one pixel one element type). A protective film that covers the insulating substrate, the resistor layer 140, the electrodes 151, 154, and the like is formed on the heating element plate.

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

  A thermal printer using such a thermal print head generally includes a platen roller. The platen roller is arranged so that its side surface is in contact with the heat generating region 132 with the main scanning direction 91 as an axis, and is provided to be rotatable around the axis. The thermal printer rotates the platen roller to move the thermal recording medium in the sub-scanning direction 92 while pressing the thermal recording medium inserted between the platen roller and the heat generating area 132 against the heat generating area 132. In addition, a desired image is formed on the thermal recording medium by changing the heat generation pattern of the heat generating area 132 as the thermal recording medium moves.

JP 2006-205520 A

  When the shape of the heat generating resistor 141 of the conventional thermal print head is simply rectangular, the surface temperature of the protective film near the outer periphery of the heat generating resistor 141 is such that the surface temperature of the protective film near the center of the heat generating resistor 141 is It becomes lower than the surface temperature of (see FIG. 8). This is because the heat from the heating resistor 141 is diffused through the protective film. In particular, the surface temperature of the protective film in the vicinity of the end portion of the heating resistor 141 tends to decrease. This is because heat is radiated through the electrodes 151 and 154 having high thermal conductivity.

  As a result, the temperatures at the four corners of the rectangular heating resistor 141 are most likely to drop, and the shape of one dot is distorted, resulting in a reduction in image quality. In addition, when the amount of heat generation is increased as the printing speed increases, the recording medium may be damaged in the vicinity of the central portion of the heating resistor 141 by overheating the recording medium. Further, in the vicinity of the center of the heat generating resistor portion 141, heat is generated at a temperature 182 or higher necessary for printing, and energy efficiency is low.

  Therefore, the present invention has been made to solve the above-described problems, and an object thereof is to flatten the temperature distribution in the heat generation region.

  In order to achieve the above object, a thermal print head according to the present invention includes an insulating substrate and a heating resistor that extends in the sub-scanning direction in which the recording medium travels and is formed on the insulating substrate with a constant width in the main scanning direction. And a conductive portion that is connected to an end portion of the heating resistor portion and applies a voltage in the sub-scanning direction of the heating resistor portion, and at least one end portion of the heating resistor portion is formed by a notch Branched in the main scanning direction into a first end and a second end, and a connecting portion of the conductive portion connected to at least one end of the heating resistor is connected to the first end by a slit It is branched into the 1st connection part made and the 2nd connection part connected to the 2nd end.

  In order to achieve the above object, the thermal printer according to the present invention includes an insulating substrate and heat generated by extending in the sub-scanning direction in which the recording medium travels and having a constant width in the main scanning direction on the insulating substrate. A resistance portion and a conductive portion that is connected to an end portion of the heating resistance portion and applies a voltage in the sub-scanning direction of the heating resistance portion, and at least one end portion of the heating resistance portion is notched Branching in the main scanning direction into a first end and a second end, and a connecting portion of the conductive portion to at least one end of the heat generating resistor is connected to the first end by a slit. A thermal print head that is branched into a connected first connecting portion and a second connecting portion connected to the second end portion is provided.

  According to the present invention, the temperature distribution in the heat generating region can be flattened.

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 concerning the 1st Embodiment of this invention, Comprising: It is the upper side figure which expanded a part of heat generating body board | substrate except the protective layer. (A) is AA arrow sectional drawing in FIG. 3, (b) is BB arrow sectional drawing in FIG. It is a figure for demonstrating the thermal print head which concerns on the 1st Embodiment of this invention, Comprising: It is the schematic diagram which showed the temperature distribution of the subscanning direction in the protective film surface with the schematic top view of a heat generating body board. It is a figure for demonstrating the thermal print head which concerns on the 2nd Embodiment of this invention, Comprising: It is the upper side figure which expanded a part of heat generating body board except the 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 top view to which a part of heat generating body board except the protective layer was expanded. It is a figure for demonstrating the conventional thermal print head, Comprising: It is the schematic diagram which showed the temperature distribution of the subscanning direction in the protective film surface with the schematic top view of a heat generating body board.

[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 according to the first embodiment of the present invention. FIG. 2 is a partial cross-sectional view of the thermal printer according to the first embodiment of the present invention.

  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 sink 20 is made of a metal such as aluminum and extends in the main scanning direction 91.

  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 radiating plate 20 and extends in the main scanning direction 91 in parallel with the heating element plate 30. A driving IC 62 and connectors 64 and 65 are mounted on the circuit board 60. The driving IC 62 serves as a driving circuit that generates heat in the heat generating region 32. Further, a control signal and driving power for forming a predetermined heat generation pattern in the heat generation region 32 are input via the connectors 64 and 65.

  The heating element plate 30 and the driving IC 62 are electrically connected by, for example, a bonding wire 66. Further, the driving IC 62 and the wiring pattern formed on the circuit board 60 are electrically connected by, for example, bonding wires 67. The driving IC 62 and the bonding wires 66 and 67 are sealed with a resin 68, for example.

  The thermal printer 1 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 shaft 72 with the main scanning direction 91 as a shaft 72. The platen roller 70 is disposed such that the side surface 74 is in contact with the heat generating region 32.

  When the thermal printer 1 is used, a thermal recording medium 76 is inserted between the platen roller 70 and the heat generating area 32. The thermal recording medium 76 is, for example, thermal paper, and develops color when heated to a temperature higher than the thermal printing temperature. The thermal printer 1 rotates the platen roller 70 to move the thermal recording medium 76 in the sub-scanning direction 92 perpendicular to the main scanning direction 91 while pressing the thermal recording medium 76 against the heat generating area 32. In addition, the thermal printer 1 forms a desired image on the thermal recording medium 76 by changing the heat generation pattern of the heat generation area 32 as the thermal recording medium 76 moves.

  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 view for explaining the thermal print head according to the first embodiment of the present invention, and is an enlarged top view of a part of the heating plate excluding the protective layer. 4A is a cross-sectional view taken along the line AA in FIG. 3, and FIG. 4B is a cross-sectional view taken along the line BB in FIG.

  The heating element plate 30 has an insulating substrate in which a glaze layer 36 is formed on one surface of a support substrate 34 made of an insulator such as alumina.

  A resistor layer 40 is formed on the surface of the glaze layer 36 of the insulating substrate. The resistor layer 40 has a plurality of heating resistor portions 41. The plurality of heating resistor portions 41 linearly extend with a certain width in the sub-scanning direction 92 and are arranged in order in the main scanning direction 91 with an interval therebetween. The heat generating region 32 refers to a band-shaped region in which a plurality of heat generating resistor portions 41 are arranged.

  An individual electrode (conductive portion) 51 is formed and electrically connected to one end 42 of each heating resistor portion 41. A common electrode (conductive portion) 54 is formed and electrically connected to the other end 43 of each heating resistor portion 41. The individual electrode 51 and the common electrode 54 are made of, for example, aluminum. The individual electrode 51 and the common electrode 54 are connected to the driving IC 62 via, for example, a bonding wire 66. Each heat generating resistor 41 plays a role as one heat generating element, and outputs one dot to the thermal recording medium 76 (one pixel one element type).

  Cutouts 46 and 47 are formed at the centers of the end portions 42 and 43 of the heating resistor 41 in the main scanning direction 91, respectively. The notches 46 and 47 extend from the end portions 42 and 43 of the heating resistor portion 41 toward the central portion 44 of the heating resistor portion 41 in the sub-scanning direction 92, respectively. The widths of the notches 46 and 47 become narrower from the end portions 42 and 43 of the heat generating resistor portion 41 toward the central portion 44 in the sub-scanning direction 92 of the heat generating resistor portion 41. In this embodiment, the shape of the notches 46 and 47 is a triangle. Note that a notch is not formed in the central portion 44 of the heating resistor portion 41 in the sub-scanning direction 92.

  Due to the notch 46, the end portion 42 of the heat generating resistor portion 41 is bifurcated into a first end portion 42a and a second end portion 42b. Further, by the notch 47, the end portion 43 of the heat generating resistor portion 41 is bifurcated into a first end portion 43a and a second end portion 43b.

  That is, since the thickness of the heating resistor portion 41 is constant, the sectional area of the heating resistor portion 41 in the sub-scanning direction 92 is directed from the central portion 44 of the heating resistor portion 41 in the sub-scanning direction 92 toward the end portions 42 and 43. With this, it becomes smaller. Therefore, the heat generation amount per unit area of the heat generating resistor portion 41 increases as it goes from the central portion 44 in the sub-scanning direction 92 of the heat generating resistor portion 41 toward the end portions 42 and 43.

  When the dot density of the thermal print head 10 is 300 dpi, for example, the length of the heating resistor portion 41 in the sub-scanning direction 92 is 150 μm, the width is 30 μm, and the thickness is 0.1 μm.

  Here, the length (triangular height) of each notch 46, 47 in the sub-scanning direction 92 is desirably 20 to 40% of the length of the heating resistor portion 41 in the sub-scanning direction 92, for example, 45 μm. Is formed. In addition, the widths of the cutouts 46 and 47 at the end portions 42 and 43 of the heating resistor portion 41 (triangle bases) are preferably 20 to 45% of the width of the heating resistor portion 41, respectively. The widths of the tips of the end portions 42a and 43a and the tips of the second end portions 42b and 43b are, for example, 10 μm.

  On the other hand, a slit 53 having a constant width is formed at the center in the main scanning direction 91 of the connection portion 52 of the individual electrode 51 with the heating resistor portion 41. The slit 53 is formed at the center of the connecting portion 52 of the individual electrode 51 in the main scanning direction 91. By the slit 53, the connection end 52 of the individual electrode 51 is bifurcated into a first connection 52a and a second connection 52b. The first connection part 52a and the second connection part 52b of the individual electrode 51 are electrically connected to the first end part 42a and the second end part 42b of the one end 42 of the heating resistor part 41, respectively.

  Similarly, a slit 56 having a constant width is formed at the center in the main scanning direction 91 of the connecting portion 55 of the common electrode 54 to the heating resistor portion 41. The slit 56 is formed in the center of the connecting portion 55 of the common electrode 54 in the main scanning direction 91. By the slit 56, the connection end portion 55 of the common electrode 53 is bifurcated into a first connection portion 55 a and a second connection portion 55 b. The first connection portion 55a and the second connection portion 55b of the common electrode 54 are electrically connected to the first end portion 43a and the second end portion 43b of the one end 43 of the heating resistor portion 41, respectively.

  Here, the heating element plate 30 is formed as follows, for example. 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 and a conductor are sequentially laminated on the entire surface of the glaze layer 36 by a thin film forming apparatus such as a sputtering apparatus.

  Thereafter, the electrodes 51 and 54 are formed in a predetermined shape by a photoengraving process, and then the resistor layer 40 is formed in a predetermined shape. Further, a protective film 58 that covers the resistor layer 40 and the electrodes 51 and 54 is formed, and openings are formed on the surfaces of the electrodes 51 and 54 that are connected to the bonding wires 66 by a photoengraving process.

  The effects of the thermal print head 10 and the thermal printer according to the present embodiment will be described with reference to FIG. FIG. 5 is a diagram for explaining the thermal print head according to the first embodiment of the present invention, and is a schematic diagram showing the temperature distribution in the sub-scanning direction on the surface of the protective film.

  As described above, when a rectangular heating resistor portion 141 is employed as in a conventional thermal print head (hereinafter referred to as “conventional example”), the outer peripheral portion of the heating resistor portion 141 (in particular, the heating resistor portion 141). The surface temperature of the protective film in the vicinity of the four corners) is lower than the surface temperature of the protective film in the vicinity of the central portion 145 of the heating resistor 141.

  On the other hand, in the present embodiment, notches 46 and 47 are formed at both ends 42 and 43 of the heating resistor portion 41, and the end portions 42 and 43 of the heating resistor portion 41 are respectively connected to the first end portions 42a and 43a. Bifurcated into second ends 42b and 43b. Therefore, the amount of heat generation per unit area of the heat generating resistor portion 41 increases as it goes from the central portion 44 of the heat generating resistor portion 41 in the sub-scanning direction 92 toward the end portions 42 and 43.

  It should be noted that most of the current flowing through the heating resistor portion 41 goes straight between the reference numerals 42a and 43a and between the reference symbols 42b and 43b. Only about 15 to 1/10 flows. Therefore, the amount of heat generated at the central portion 45 of the heating resistor 141 is small.

  Further, in the present embodiment, slits 53 and 56 are formed in the connection portions of the individual electrode 51 and the common electrode 54 with the heat generating resistor portion 41, respectively. Therefore, in the present embodiment, compared to the conventional example, the heat from the heating resistor portion 41 is less likely to be radiated through the electrodes 51 and 54, and the first ends 42a and 43a and the first end portions located at the four corners of the heating resistor portion 41 and The surface temperature of the protective film near the two end portions 42b and 43b is increased.

  As described above, the temperature distribution 81 in the vicinity of the heat generating region 32 of the thermal print head according to the present embodiment is flattened compared to the temperature distribution 181 in the vicinity of the heat generating region 32 of the conventional example. As a result, the shape of one dot is not distorted and the image quality is improved. Further, even when the amount of heat generation is increased as the printing speed is increased, damage to the thermal recording medium 76 is suppressed without overheating the thermal recording medium 76 in the vicinity of the central portion 45 of the heating resistor portion 41. it can. Furthermore, excessive heat generation near the center 44 of the heating resistor portion 41 can be suppressed, and energy efficiency can be improved.

[Second Embodiment]
A thermal print head according to a second embodiment of the present invention will be described with reference to FIG. FIG. 6 is a view for explaining a thermal print head according to the second embodiment of the present invention, and is an enlarged top view of a part of the heating plate excluding the protective layer. In addition, since this embodiment is a modification of 1st Embodiment, duplication description is abbreviate | omitted.

  In the present embodiment and the first embodiment, the shapes of the notches 46 and 47 are different. In the present embodiment, the notches 46 and 47 extend from the end portions 42 and 43 of the heating resistor portion 41 with a certain width toward the central portion 44 in the sub-scanning direction 92 of the heating resistor portion 41, respectively. Is rounded near the central portion 44.

  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. 7 is a view for explaining a thermal print head according to the third embodiment of the present invention, and is an enlarged top view of a part of the heating plate excluding the protective layer. In addition, since this embodiment is a modification of 1st Embodiment, duplication description is abbreviate | omitted.

  In the present embodiment, a plurality of resistor layers 40 are formed on the glaze layer 36. Each resistor layer 40 is formed in a substantially U-shaped pattern. The plurality of resistor layers 40 are arranged side by side in the main scanning direction 91 at intervals.

  The substantially U-shaped resistor layer 40 is constituted by a series of two heating resistor portions 41 and a folding resistor portion. The two heat generating resistance portions 41 are portions that extend in the sub-scanning direction 92 and are arranged at intervals in the main scanning direction 91. The folding resistance portion is a portion that connects the ends 43 of the two heating resistance portions 41. An individual electrode 51 is connected to one end of each of the two heating resistor portions 41.

  A conductive layer (conductive portion) 96 is laminated on the surface of the folded resistance portion, and the conductive layer 96 electrically connects the two heating resistance portions 41 to each other. When a voltage is applied between the individual electrodes 51, a current flows in the order of the heating resistor 41, the conductive layer 96, and the heating resistor 41, and the two heating resistors 41 generate heat simultaneously. That is, one dot is output to the thermal recording medium 76 from the two heating resistor portions 41 (one pixel two element type).

  Also in the present embodiment, notches 46 and 47 are formed in the heating resistor 41 and slits 53 are formed in the individual electrodes 51 as in the first embodiment. A slit 98 is also formed in the connection portion of the conductive layer 96. By the slit 98, the connection end portion of the individual electrode 51 is bifurcated into a first connection portion 97a and a second connection portion 97b.

  Also according to this embodiment, the same effect as that of the first embodiment can be obtained. Further, in the present embodiment, unlike the first embodiment, the common electrode 54 is not adopted. Therefore, the image quality is not deteriorated by the common drop, and further, the space for arranging the common electrode 54 becomes unnecessary, and the thermal print head 10 can be downsized.

[Other Embodiments]
In the first to third embodiments, the two notches 46 and 47 formed in the heating resistor portion 41 have the same size and shape, but the notches are used so that the temperature distribution is further flattened. The size and shape of 46 and 47 may be changed.

  Further, 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.

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, 38 ... Resistor layer, 40 ... Resistor layer, 41 ... Heat generating resistor part, 42 ... an end of the heating resistor, 42a ... a first end, 42b ... a second end, 43 ... an end of the heating resistor, 43a ... a first end, 43b ... a second end, 44 ... a heating resistor 45... Central portion of the heating sub-scanning direction, 45... Central portion of the heating resistor 46, 47. Notch, 51. Individual electrode (conductive portion), 52. Individual electrode connection portion, 52 a. ... Second connection part, 53 ... Slit for individual electrode, 54 ... Common electrode (conductive part), 55 ... Connection part for common electrode, 55a ... First connection part, 55b ... Second connection part, 56 ... Slit for common electrode 58 ... Protective film, 60 ... Circuit board, 62 ... Driving IC, 64, 65 ... Connector , 66, 67 ... bonding wire, 68 ... resin, 70 ... platen roller, 72 ... platen roller shaft, 74 ... side surface of platen roller, 76 ... thermal recording medium, 81 ... temperature distribution in the sub-scanning direction on the surface of the protective film , 82 ... temperature required for printing, 83 ... center position in the sub-scanning direction of the heat generation area, 91 ... main scanning direction, 92 ... sub-scanning direction, 96 ... conductive layer (conductive part), 97a ... first connection part, 97b ... Second connection part, 98 ... Slit of conductive layer

Claims (6)

An insulating substrate;
A heating resistor extending in the sub-scanning direction in which the recording medium travels and having a constant width in the main scanning direction on the insulating substrate;
A conductive part that is connected to an end of the heating resistor and applies a voltage in the sub-scanning direction of the heating resistor;
In the thermal print head equipped with
At least one end portion of the heating resistor portion is branched into a first end portion and a second end portion in the main scanning direction by a notch,
The connecting portion of the conductive portion to at least one end of the heating resistor portion includes a first connecting portion connected to the first end by a slit and a second connecting portion connected to the second end. A thermal print head characterized by branching into two.   The notch extends from the end of the heating resistor to the center of the heating resistor in the sub-scanning direction, and the width of the notch extends from the end of the heating resistor to the heating resistor. The thermal print head according to claim 1, wherein the thermal print head becomes narrower toward a center portion in the sub-scanning direction.   Two notches are formed in one heating resistor portion, and the two notches are opposed to each other, respectively, from both ends of the heating resistor portion in the sub-scanning direction of the heating resistor portion. The thermal print head according to claim 1, wherein the thermal print head extends toward a central portion.   4. The length of the notch in the sub-scanning direction is 20% or more and 40% or less of the length of the heating resistor portion in the sub-scanning direction. 5. The thermal print head described.   5. The thermal according to claim 1, wherein a width of the notch at an end portion of the heat generating resistor portion is 20% or more and 45% or less of a width of the heat generating resistor portion. Print head.   An insulating substrate; a heating resistor extending in the sub-scanning direction in which the recording medium travels and formed on the insulating substrate with a constant width in the main scanning direction; and the heating resistor connected to an end of the heating resistor. A conductive portion for applying a voltage in the sub-scanning direction, and at least one end portion of the heating resistor portion is branched into a first end portion and a second end portion in the main scanning direction by a notch. The connecting portion of the conductive portion to the at least one end portion of the heating resistor portion is connected to the first end portion connected to the first end portion by the slit and the second end portion connected to the second end portion. A thermal printer comprising a thermal print head branched to a connection portion.

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