JP6010413B2 - Thermal print head and manufacturing method thereof - Google Patents

Description

  The present invention relates to a thermal print head and a manufacturing method thereof.

  Thermal print heads are used in mobile printers such as barcode label printers, POS printers, lightweight label printers, and handy terminals. The thermal print head performs recording on thermal paper, plate-making film photographic paper, media, and the like by causing the heating resistors arranged on the support base to generate heat.

  The support substrate of the thermal print head is obtained by forming a glaze layer as a heat retaining layer on a ceramic substrate such as alumina. The glaze layer is partially formed only in the vicinity of the heating resistor or formed on the entire surface of the ceramic substrate. Furthermore, a ridge part may be provided in a part of glaze layer. A resistor layer and an electrode layer are laminated on the surface of the support substrate by a thin film forming method such as sputtering, and a patterning process is performed to form a pair of heating resistors and individual electrodes on one line. Further, the head substrate of the thermal print head is formed by forming a protective coating layer on a necessary portion of the resistor layer and the electrode layer by a thin film forming method such as sputtering.

  The head substrate and a separately manufactured circuit board are combined with a heat sink. For bonding the head substrate to the heat sink, a method such as fixing with an adhesive or double-sided tape is generally used. After the combination of the head substrate, the circuit substrate and the heat sink, the electrode is connected to the circuit substrate via a driving IC (Integrated Circuit) with a bonding wire. A thermal print head is completed by resin-sealing the bonding wires.

JP 2003-165241 A

  When the resistor layer, the electrode layer, and the protective coating layer are laminated on the support substrate, a step corresponding to the thickness of the electrode layer is generated in the protective coating layer in a region where the electrode layer does not exist in the heat generating portion. If this step is present, an air gap may occur at a portion where the thermal print head contacts the printing medium. When such an air gap occurs, heat is not efficiently transferred to the printing medium, print quality is deteriorated, and energy efficiency is lowered.

  Furthermore, cracks are likely to occur in the protective coating layer at such stepped portions, and when cracks occur, corrosion progresses due to the solvent used at the time of cleaning, which may impair the soundness of the thermal print head. Further, damage may occur due to static electricity.

  Therefore, an object of the present invention is to improve the print quality of a thermal print head.

In order to solve the above-described problems, the present invention provides a thermal printhead in which the insulating substrate and the surface of the insulating substrate are arranged in the main scanning direction with a space therebetween, and are each in the sub-scanning direction perpendicular to the main scanning direction. A plurality of heating resistors extending; electrodes extending from both ends of each of the heating resistors in the sub-scanning direction; insulators covering the heating resistors; and each of the heating resistors An upper surface resistor layer disposed on the opposite side across the insulator and connected to the electrodes on the upstream side and the downstream side in the sub-scanning direction of the heating resistor, and an upper surface covering the upper surface resistor layer comprising a coating layer, wherein the insulator is characterized in that have a protrusion glaze projecting from the insulating substrate extends linearly in the main scanning direction are formed of glass.

According to the present invention, in the method for manufacturing a thermal print head, a plurality of heating resistors arranged in the main scanning direction at intervals on the surface of the insulating substrate and extending in the sub-scanning direction perpendicular to the main scanning direction, and A first step of forming electrodes extending in the sub-scanning direction from both ends of each of the heating resistors in the sub-scanning direction; a second step of covering the heating resistor with an insulator after the first step; After the second step, the upper surface resistors arranged on the opposite sides of the insulator with respect to each of the heating resistors and connected to the electrodes on the upstream side and the downstream side in the sub-scanning direction of the heating resistor A third step of forming a body layer, and a fourth step of coating the upper surface resistor layer with an upper surface coating layer after the third step , wherein the heating resistor is arranged in the second step. Glass page DOO is applied, protrusions glaze forming step of obtaining a projection glaze and firing the glass paste, characterized in that it comprises a.

  According to the present invention, the print quality of the thermal print head is improved.

It is a partial expanded sectional view of one embodiment of a thermal print head concerning the present invention. 1 is a partially enlarged plan view of a part of an embodiment of a thermal print head according to the present invention. 1 is a cross-sectional view of a thermal printer using an embodiment of a thermal print head according to the present invention. It is sectional drawing in several steps of the manufacture process in one Embodiment of the thermal print head concerning this invention. It is surface temperature distribution by one Embodiment of the thermal print head concerning this invention.

  An embodiment of a thermal print head according to the present invention will be described with reference to the drawings. Each of the embodiments is merely an example, and the present invention is not limited to this.

  FIG. 1 is a partially enlarged sectional view of an embodiment of a thermal print head according to the present invention. FIG. 2 is a partially enlarged plan view of a part of the thermal print head according to the present embodiment. FIG. 3 is a cross-sectional view of a thermal printer using the thermal print head of the present embodiment.

  The thermal print head 10 according to the present embodiment includes a heat radiating plate 30, a heat generating plate 20, and a circuit board 40. The heat sink 30 is a rectangular flat plate made of a metal such as aluminum.

The heating element plate 20 has an insulating substrate including a ceramic substrate 22 and an entire glaze layer 25. The ceramic substrate 22 is a rectangular flat plate made of alumina (Al ₂ O ₃ ), for example. One surface of the ceramic substrate 22 faces the heat sink 30, and the entire glaze layer 25 is fused to the other surface. The entire glaze layer 25 is made of glass.

  A resistor layer 26 is formed on the entire surface of the glaze layer 25. An electrode layer 28 is formed on the surface of the resistor layer 26. A notch portion is formed in the electrode layer 28, and a portion of the resistor layer 26 that does not overlap the electrode layer 28 is a heating resistor. In this manner, a plurality of heating resistors are arranged on the entire surface of the glaze layer 25 at intervals, and a belt-like heating region 24 extending in the longitudinal direction (main scanning direction) of the ceramic substrate 22 is formed.

  A protective coating layer 29 is formed on the surfaces of the electrode layer 28 and the heating resistor. The protective coating layer 29 is made of, for example, SiON. Openings 73 are formed in a part of the protective coating layer 29 on the upstream side and the downstream side in the sub-scanning direction of the heat generating region 24.

  A ridge glaze 71 is formed in a region sandwiched between the openings 73. The ridge glaze 71 has a maximum thickness of about 40 μm and extends linearly in the main scanning direction. The ridge glaze 71 is made of glass. The surface of the ridge glaze 71 draws a smooth arc in the sub-scanning direction.

  An upper surface resistor layer 72 is formed on the surface of the ridge glaze 71. The upper surface resistor layers 72 are arranged at the same pitch as the heating resistors in the main scanning direction. Both end portions of the upper surface resistor layer 72 in the sub-scanning direction are connected to the electrode layer 28 through the openings 73 formed in the protective coating layer 29. The surface of the upper surface resistor layer 72 is covered with the upper surface film layer 70.

  The thermal print head 10 also has a drive circuit that generates heat in the heat generating region 24. The drive circuit is formed on a circuit board 40 mounted on the heat dissipation plate 30 on the same surface as the heating element plate 20, for example. A control signal and driving power for forming a predetermined heat generation pattern in the heat generation region 24 are input to the circuit board 40. The drive circuit has electrical components such as a drive element 42 provided on the circuit board 40, for example. The heat generating plate 20 and the drive circuit are electrically connected by, for example, a bonding wire 44 spanned between the heat generating plate 20 and the circuit board 40. Further, the wiring pattern formed on the surface of the circuit board 40 and the drive element 42 are also electrically connected by the bonding wire 44. The drive element 42 and the bonding wire 44 are sealed with a resin 48, for example.

  The printer using the thermal print head 10 has a cylindrical platen roller 50 centering on an axis 52 located on the normal line of the surface of the heat generating area 24. The printing medium 60 is pressed against the thermal print head 10 by the platen roller 50. In this state, the heat generating resistor in the heat generating region 24 generates heat, and the image is printed on the printing medium 60. While the printing medium 60 is conveyed in the sub-scanning direction, the heat generating area 24 extending in the main scanning direction generates heat in a predetermined pattern, so that a desired image is formed on the printing medium 60.

  Next, the manufacturing method of this Embodiment is demonstrated.

  FIG. 4 is a cross-sectional view at several stages of the manufacturing process of the thermal print head according to the present embodiment.

  First, a glass paste is printed on the main surface of the ceramic substrate 22. The thickness of the glass paste is, for example, 30 to 120 μm. Thereafter, the glass paste attached to the ceramic substrate 22 is fired. At this time, the temperature of the glass paste is set to a temperature equal to or higher than the softening point temperature of the glass, held for a predetermined time, and then cooled to room temperature. Thereby, the entire glaze layer 25 is formed.

  Next, a resistance film layer and a metal layer are formed on the entire surface of the glaze layer 25. The resistor layer 26 and the electrode layer 28 having a predetermined pattern are formed by etching the resistance film layer and the metal layer into a predetermined shape.

  Thereafter, a protective coating layer 29 that covers the resistor layer 26 and the electrode layer 28 is formed. The protective coating layer 29 is formed by sputtering, for example.

  A glass paste 75 is applied to the surface of the protective coating layer 29. As a result, the state shown in FIG. The glass paste 75 is applied in a strip shape extending in the main scanning direction so as to cover the heat generating region 24.

  Thereafter, the glass paste 75 is set to a temperature equal to or higher than the softening point temperature of the glass, held for a predetermined time, and then cooled to room temperature. By baking the glass paste 75 in this manner, the glass paste 75 becomes fluid at a temperature higher than the softening point, becomes fluid, and has a rounded shape due to the action of surface tension and gravity. Is formed. As a result, the state shown in FIG. The firing temperature at this time is lower than the firing temperature when the entire glaze layer 25 is formed.

  In order to prevent the entire glaze layer 25 from being softened when the glass paste 75 is fired, it is preferable to use a glass paste 75 that has a lower softening point than the entire glaze layer 25 as the glass glaze 71.

  Next, a part of the protective coating layer 29 is etched by photolithography or the like to form the opening 73. The openings 73 are formed on the surface of the electrode layer 28 arranged in the main scanning direction on both sides of the ridge glaze 71 in the sub scanning direction. As a result, the state shown in FIG.

  Thereafter, a resistor layer is formed on the surface of the protective coating layer 29 by sputtering or the like, and then patterned by photolithography or the like, whereby the upper surface resistor layer 72 having a predetermined pattern is formed. As a result, the state shown in FIG. Thereafter, the heating element plate 20 is obtained by forming the upper surface coating layer 70 on the surface of the upper surface resistor layer 72. The circuit board 40 on which the heating element plate 20 and the driving element 42 manufactured in this manner are mounted is placed on the heat dissipation plate 30, and the bonding wire 44 is bridged between the driving element 42 and the heating element plate 20 to drive the circuit board 40. The thermal print head 10 is completed by sealing the element 42 and the bonding wire 44.

  FIG. 5 shows the surface temperature distribution of the thermal print head of this embodiment.

  When the heating resistor of the thermal print head of the present embodiment is energized, the heating region 24 generates heat and the top resistor layer 72 also generates heat. In the region where the top resistor layer 72 is present (indicated by A in FIG. 5), the maximum value is obtained at the central portion in the sub-scanning direction, and the temperature gradually decreases on both sides. Only the heat generation of the upper surface resistor layer 72 is set so as not to reach the coloring temperature of the printing medium 60.

  In the heat generation region 24 (indicated by B in FIG. 5), the heat generation of the resistor layer 26 and the upper surface resistor layer 72 causes the heat generation amount to be larger than both sides in the sub-scanning direction, and a sharp temperature peak is obtained. This temperature peak is set to be equal to or higher than the color development temperature.

  As described above, the thermal print head of the present embodiment can realize a temperature distribution having a sharp temperature peak on the surface of the heat generating region 24. Therefore, it is possible to increase the surface temperature of the thermal print head 10 on the upstream side and the downstream side of the heat generating region 24 while miniaturizing the printing dots.

  As described above, in the thermal print head according to the present embodiment, the gap of the electrode layer 28 in the heat generating region 24 is covered with the ridge glaze 71, and a step is formed on the surface of the upper surface protective film 70 that is in contact with the printing medium 60. Is not formed. For this reason, malfunctions, such as generation | occurrence | production of the crack resulting from a level | step difference, can be suppressed. Further, since there is no air gap due to the step, heat is efficiently transferred to the printing medium 60, and energy efficiency is improved. As a result, the print quality of the thermal print head 10 is improved.

  Further, it has a sandwich structure in which an upper surface resistor layer 72 is provided with an insulator such as the ridge glaze 71 interposed therebetween. That is, it has a resistor electrically parallel to the thickness direction. These parallel resistors are isolated by an insulating layer called a ridge glaze 71. Heat is stored in the insulating layer between the electrically parallel resistors. Thereby, the base temperature of these resistors can be raised. As a result, when actually printing, it is possible to print with less energy. Further, by utilizing this stored heat, the print quality can be improved without preheating, which is particularly effective when the battery capacity of a low temperature environment or a mobile device is limited.

DESCRIPTION OF SYMBOLS 10 ... Thermal print head, 20 ... Heat generating board, 22 ... Ceramic substrate, 24 ... Heat generating area, 25 ... Full glaze layer, 26 ... Resistor layer, 28 ... Electrode layer, 29 ... Protective coating layer, 30 ... Heat sink, DESCRIPTION OF SYMBOLS 40 ... Circuit board, 42 ... Drive element, 44 ... Bonding wire, 48 ... Resin, 50 ... Platen roller, 52 ... Shaft, 60 ... Printed medium, 70 ... Upper surface coating layer, 71 ... Projection glaze, 72 ... Upper surface resistance Body layer, 73 ... opening, 75 ... glass paste

Claims (6)

An insulating substrate;
A plurality of heating resistors arranged in the main scanning direction at intervals on the surface of the insulating substrate and extending in the sub-scanning direction perpendicular to the main scanning direction;
Electrodes extending in the sub-scanning direction from both ends in the sub-scanning direction of each of the heating resistors;
An insulator covering the heating resistor;
An upper surface resistor layer disposed on the opposite side of the insulator with respect to each of the heating resistors and connected to the electrodes on the upstream side and the downstream side in the sub-scanning direction of the heating resistor;
An upper surface coating layer covering the upper surface resistor layer;
Equipped with,
The insulator thermal printhead characterized by have a ridge glaze projecting from the insulating substrate extends formed of glass the main scanning direction linearly.   The thermal print head according to claim 1, wherein a surface of the insulator has a smooth arc in the sub-scanning direction. The said insulating substrate has the whole surface glaze layer formed with glass on the outermost surface, The softening point of the said protrusion glaze is lower than the softening point of the said whole surface glaze layer, The Claim 1 or 2 characterized by the above-mentioned. Thermal print head. The insulator has a protective coating layer that covers the electrode layer and the heating resistor, and openings are formed on the surface of the protective coating layer on both sides in the sub-scanning direction with respect to the ridge glaze. The thermal print head according to any one of claims 1 to 3 . A plurality of heating resistors arranged in the main scanning direction at intervals on the surface of the insulating substrate and extending in the sub scanning direction perpendicular to the main scanning direction, and the heating resistors from both ends in the sub scanning direction, respectively. A first step of forming an electrode extending in the sub-scanning direction;
A second step of covering the heating resistor with an insulator after the first step;
After the second step, the upper surface is disposed on the opposite side of the heating resistor with respect to each of the heating resistors and is connected to the electrodes on the upstream side and the downstream side in the sub-scanning direction of the heating resistor. A third step of forming a resistor layer;
A fourth step of coating the upper resistor layer with an upper surface coating layer after the third step;
Equipped with,
The second step includes a step of forming a ridge glaze by applying a glass paste to a region where the heating resistors are arranged and firing the glass paste to obtain a ridge glaze. Manufacturing method. The first step, a glass paste is applied to the entire surface of the ceramic substrate, comprising the entire surface glaze forming process, to obtain the entire surface glaze layer by firing the glass paste, the firing temperature of the rib glaze forming step, the 6. The method of manufacturing a thermal print head according to claim 5 , wherein the temperature is lower than a firing temperature in the entire surface glaze forming step.

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