JP2011056823A - Thermal print head and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate installation of a thermal print head having a heating area on a tilt surface of a protrusion near an end edge to a thermal printer. <P>SOLUTION: The thermal print head includes an insulation plate 22, a heat reserving layer 25 having a protrusion 21 abutted to an end edge of a main surface of the insulation plate 22 and extended like a band on the main surface and having the tilt surface on both sides of a top part, a plurality of resistors 23 arranged with intervals in a direction in which the protrusion is extended on the tilt surface nearer to the end edge of the protrusion 21, electrodes 28 opposed to have the heating area 24 positioned on the tilt surface nearer to the end edge of the protrusion 21 therebetween on the surfaces of the resistor 23, and a protecting layer 29 covering the heat reserving layer 25, the resistors 23 and the electrodes 28. A flat part 71 is formed in an area in the prescribed length of the front and the rear of the heating area 24 in the direction crossing the protrusion 21 on the surface of the protecting layer 29. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

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

  The thermal print head is an output device that heats a plurality of resistance heating elements arranged in the main scanning direction and forms images such as characters and figures on a printing medium such as a thermal recording paper by the heat. This thermal print head is widely used in recording devices such as barcode printers, digital plate-making machines, video printers, imagers, and seal printers.

  A general thermal print head includes a heat radiating plate, a heat generating plate attached to the heat radiating plate, and a circuit board attached to the heat radiating plate on the same side as the heat generating plate. Heat generating resistors are linearly arranged at predetermined intervals in a heat generating region extending in a band shape on the surface opposite to the surface of the heat generating plate opposite to the heat radiating plate. In addition, a driver IC that is a part of a drive circuit that drives the heating element is mounted on, for example, a heating element plate.

  A printer using such a thermal print head generally includes a platen roller formed in a cylindrical shape with a material having a predetermined elasticity. The platen roller is disposed so that its side surface is in contact with the heat generation area on the support substrate with the main scanning direction as an axis, and is provided to be rotatable about the axis. Due to the rotation of the platen roller, the medium inserted between the platen roller and the heat generating area moves in the sub-scanning direction perpendicular to the main scanning direction. While pressing the medium against the heat generation area by the platen roller, the medium is moved in the sub-scanning direction, and the heat generation pattern of the heat generation area is changed with the movement of the medium, thereby forming a desired image on the printing medium.

  When the printing medium is hard, the passage path of the printing medium at the time of printing needs to be a straight line. In order to increase the printing speed, it is preferable that the passage path of the print medium is as simple as possible as a straight line.

  When the surface in the vicinity of the heat generating portion of the thermal print head is flat, it is impossible to transport the print medium by such a straight path. Further, even when a protrusion is provided on the heat retaining layer of the thermal print head, it is difficult to ensure such a straight path due to interference with the resin protecting the driver IC and the like.

  On the other hand, in an end face type thermal print head in which a heat generating area is formed on the end face of the insulating substrate, and a corner edge type thermal print head in which a slope is formed near the end of the insulating substrate and a heat generating area is formed on the slope, It is relatively easy to secure a straight path. However, since the end face type or corner edge type thermal print head is relatively difficult to manufacture, the manufacturing cost tends to increase.

  Therefore, there is a case where a near-edge structure is employed as a structure of the thermal print head so that a hard print medium does not interfere with a resin protecting the driver IC or the like. In the near edge structure, a heat generating region is arranged on the opposite side of the driver IC across the apex of the glaze layer formed on the ridge, and the heat generating region is provided very close to the end of the heat generating plate (see, for example, Patent Document 1). ). In the near edge structure, since a heat generation region is formed on the main surface of the insulating substrate, it is not necessary to form a resistance film or the like on a narrow end surface. In addition, it is necessary to form a slope on the insulating substrate. For this reason, the thermal printing head having the near edge structure can be manufactured at a relatively low cost compared to the end face type or the corner edge type.

Japanese Patent Application No. 2005-262828

  In a thermal printer using a thermal print head, a printing medium is pressed against a heat generating area by a platen roller. Since the heat transfer from the heat generation area to the print medium increases as the print medium comes into close contact with the heat generation area, the rotation axis of the platen roller is positioned in the normal direction of the surface of the thermal print head in the heat generation area. Is preferred.

  In the end face type thermal print head, the normal direction of the surface of the thermal print head in the heat generation region is parallel to the main surface of the thermal print head, so that the positioning of the platen roller is relatively easy. Even in the case of a corner edge type thermal print head, the normal direction of the surface of the thermal print head in the heat generation area forms a predetermined angle with the main surface of the thermal print head, so that the positioning of the platen roller is relatively easy. is there.

  In a thermal print head having a near-edge structure in which a heat generation region is provided on the surface of the glaze layer formed on the ridge, the heat generation region is formed on the slope of the ridge having an arc in cross section. For this reason, the normal direction of the surface of the thermal print head in the heat generation region changes due to the shift of the heat generation region in the sub-scanning direction. Moreover, since the protrusion of the glaze layer smoothes the glass at a high temperature, it is difficult to control the cross-sectional shape. As a result, even in the case of thermal print heads manufactured under the same design conditions, the normal direction of the surface of the thermal print head in the heat generation region may change.

  If the normal direction of the surface of the thermal print head in the heat generating region changes, relative positioning becomes difficult when the thermal print head and the platen roller are attached to the thermal printer. If accurate positioning is not possible, printing accuracy is reduced, and manufacturing costs may increase if accurate positioning is attempted.

  In view of this, the present invention provides a thermal print head having a heat generating area on the opposite side of the driver IC across the apex of the glaze layer formed on the ridge, and the heat generating area provided in the immediate vicinity of the end of the heat generating plate. It is intended to facilitate installation to a printer.

  In order to solve the above-described problems, the present invention provides a thermal print head in which a slope is formed on both sides of a top portion of an insulating plate and a main surface of the insulating plate, extending in a strip shape in contact with an edge of the main surface. An insulating substrate having a heat insulating layer provided with a ridge, a plurality of resistors arranged at intervals in a direction in which the ridge extends on a slope closer to the end edge, and the end of the resistor on the surface of the resistor A wiring layer comprising electrodes provided facing each other across a heat generation region located on the slope closer to the edge, and a direction crossing the ridges covering the insulating substrate, the resistor, and the electrode And a protective layer in which a surface region having a predetermined length before and after the heat generating region is formed flat.

  Further, the present invention provides a method for manufacturing a thermal print head, comprising: an insulating plate; and a ridge that extends in a strip shape on the main surface of the insulating plate in contact with the edge of the main surface and has slopes formed on both sides of the top portion. A step of forming an insulating substrate having a heat retaining layer, a plurality of resistors arranged at intervals in a direction in which the ridges extend on a slope closer to the edge of the ridges, and the resistors Forming a wiring layer having an electrode provided opposite to the surface of the protrusion with a heat generation region located on the slope closer to the edge of the ridge, the insulating substrate and the resistor, A protective layer forming step of forming a protective layer covering the electrode; and a region having a predetermined length in a direction crossing the ridge of the slope closer to the end edge of the ridge of the protective layer. Protective layer polisher that forms a flat part by polishing at a predetermined angle with respect to the main surface of Characterized by comprising the, the.

  Further, the present invention provides a method for manufacturing a thermal print head, comprising: an insulating plate; and a ridge that extends in a strip shape on the main surface of the insulating plate in contact with the edge of the main surface and has slopes formed on both sides of the top. A step of forming an insulating substrate having a heat insulating layer, and a region having a predetermined length in a direction crossing the protrusion on the slope closer to the edge of the protrusion of the heat insulating layer. Polishing the main surface at a predetermined angle to form a flat portion; a plurality of resistors arranged at intervals in a direction in which the protrusions extend in the flat portion; and the surfaces of the resistors A step of forming a wiring layer provided with electrodes provided facing each other across a heat generation region located on a slope closer to the edge of the ridge, and the insulating substrate, the resistor, and the electrode Forming a covering protective layer.

  According to the present invention, the heat generating area is arranged on the opposite side of the driver IC across the apex of the glaze layer formed on the ridge, and the heat generating area is provided in the vicinity of the end of the heat generating plate. Easy to attach to the printer.

It is a fragmentary sectional view of the heat generating body board in 1st Embodiment of the thermal print head concerning this invention. 1 is a partially cutaway top view of a first embodiment of a thermal print head according to the present invention. 1 is a partial sectional view of a thermal printer using a first embodiment of a thermal print head according to the present invention. It is a flowchart of the manufacturing method of the thermal print head in this Embodiment. It is a fragmentary sectional view of the heat generating body board after the protective layer formation process in 1st Embodiment of the thermal print head concerning this invention. It is a fragmentary sectional view of the heat generating body board at the time of the grinding | polishing process in 1st Embodiment of the thermal print head concerning this invention. It is a fragmentary sectional view of the heat generating body board in 2nd Embodiment of the thermal print head concerning this invention. It is a fragmentary sectional view of the heat generating body board in 3rd 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. In addition, the same code | symbol is attached | subjected to the same or similar structure, and the overlapping description is abbreviate | omitted.

[First Embodiment]
FIG. 3 is a partial sectional view of a thermal printer using the first embodiment of the thermal print head according to the present invention.

  The thermal print head 10 of the present embodiment includes, for example, a heating plate 20, a circuit board 40, and a heat sink 30. The heat generating plate 20 is formed with a heat generating region 24 extending in a strip shape in the main scanning direction. The heating plate 20 is placed on the heat sink 30. The heat sink 30 is a plate formed of a metal such as aluminum. 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 and further input to the heating element plate 20 electrically connected to the circuit board 40.

  The thermal printer using the thermal print head 10 has a fixed base 54 and a platen roller 50. The fixed base 54 has a reference surface 56. The thermal print head 10 is placed on the reference surface 56 of the fixed base 54 and fixed to the fixed base 54 with screws 55. The platen roller 50 is formed in a cylindrical shape from a material having a predetermined elasticity, and has an axis 52 parallel to the main scanning direction. The shaft 52 is located in the normal direction of the surface of the heat generating plate 20 in the heat generating region 24. The platen roller 50 is disposed such that its side surface is in contact with the heat generating region 24, and is provided to be rotatable about a shaft 52.

  Due to the rotation of the platen roller 50, the printing medium 60 inserted between the platen roller 50 and the heat generating area 24 moves in the sub-scanning direction perpendicular to the main scanning direction. The printing medium 60 is, for example, thermal paper that develops color when heated to a color development temperature or higher. While the printing medium 60 is pressed against the heat generation area 24 by the platen roller 50, the printing medium 60 is moved in the sub-scanning direction, and the heat generation pattern of the heat generation area 24 is changed along with the movement of the printing medium 60. An image is formed on the printing medium 60. The print medium 60 may be a combination of a hard card or the like and a heat sensitive film that moves with the card.

  FIG. 1 is a partial cross-sectional view of a heating plate in the present embodiment. FIG. 2 is a partially cutaway top view of the thermal print head of the present embodiment.

The heating element plate 20 includes an insulating plate 22, a heat insulating layer 25, a resistor 23, an electrode 28, and a protective layer 29. The insulating plate 22 is made of an insulator such as alumina (Al ₂ O ₃ ). The heat insulating layer 25 is formed in layers on the surface of the insulating plate 22, for example, with silicon oxide (SiO ₂ ). Further, a protrusion 21 is formed on a part of the heat insulating layer 25. The protrusion 21 has a shape obtained by cutting, for example, a cylinder or an elliptical column by a plane parallel to the axis.

  The ridges 21 are provided in a strip shape having a predetermined width in contact with the edge of the insulating plate 22. The protrusion 21 is a part of the heat insulating layer 25 that protrudes from the main surface of the insulating plate 22 to the top 74 that extends along the edge of the insulating plate 22. Slopes 75 and 76 are formed on both sides of the top portion 74 of the ridge 21, that is, from the linear top portion 74 toward the upstream side and the downstream side in the sub-scanning direction. Both the slopes 75 and 76 are formed to protrude outward. In the cross section cut perpendicularly to the main scanning direction, the surface of the ridge 21 forms an arc.

  The resistor 23 is formed in layers on the surface of the heat insulating layer 25, for example, with cermet. The resistors 23 are arranged at intervals in the direction in which the edge of the insulating plate 22 extends. Moreover, the resistor 23 is extended over the protrusion 21, respectively.

  The electrode 28 is formed on the surface of the resistor 23 in a layered manner, for example, with aluminum. The electrodes 28 are provided to face each other with a gap in the direction in which the resistor located on the slope closer to the edge of the protrusion 21 extends. Since the current flowing through the electrode 28 passes through the resistor 23 in the gap portion, the portion corresponding to the gap of the resistor 23 becomes the heat generating region 24. The heat generating portions are arranged at intervals in the direction in which the edge of the insulating plate 22 extends, that is, in the main scanning direction, to form a heat generating region 24 extending in the main scanning direction.

  As described above, the thermal print head 10 according to the present embodiment has a near edge structure in which the heat generating region 24 is provided on the opposite side of the driver IC 42 across the ridge line of the heat insulating layer 25 formed on the ridge 21. .

  The heat insulating layer 25, the resistor 23, and the electrode 28 are covered with a protective layer 29. The protective layer 29 is not provided on a part of the surface of the electrode 28, and a bonding wire 44 is connected to that part. The electrode 28 is connected to the driver IC 42 on the circuit board via the bonding wire 44. The driver IC 42 and the bonding wire 44 are sealed with a resin 48.

  The protective layer 29 is formed with a flat portion 71 having a flat surface. This flat portion occupies a region of a predetermined length before and after the heat generating region 24 in the direction crossing the protrusion 21, that is, in the sub-scanning direction. In other words, the normal line is parallel to the normal direction 70 in the heat generating region 24 at any location of the flat portion 71. Further, this flat portion extends over the entire surface of the protective layer 29 in the main scanning direction. The flat part 71 has, for example, an inclination of about 10 degrees with respect to the lower surface of the heat sink 30.

  FIG. 4 is a flowchart of the method for manufacturing the thermal print head in the present embodiment.

  In the method for manufacturing a thermal print head in the present embodiment, first, an insulating plate is formed (S1). The insulating plate has such a size that a plurality of finally produced heating element plates 20 are cut out.

  Next, a glass paste is pattern-printed on the insulating plate formed in step S1 (S2). The glass paste printed here is a pattern in which a band-like raised portion is formed at a position corresponding to each protrusion 21 of the plurality of heating element plates 20.

  Next, the insulating plate on which the glass paste is printed is baked (S3). Thereby, the glass on which the pattern is printed is melted and fixed to the insulating plate. As a result, the heat insulating layer 25 including the protrusions 21 is formed. This step (S3) is called a heat insulating layer forming step.

  Thereafter, the resistor 23 and the electrode 28 are formed on the surface of the heat insulating layer 25 (S4). More specifically, first, a resistance material such as cermet is fixed to the surface of the heat insulating layer 25 by sputtering or the like. Thereafter, the resistor 23 is patterned by etching so as to form resistors arranged at intervals in the extending direction of the ridge 21 on the slope of the ridge 21. Further, a conductive material such as aluminum is fixed to the plate on which the resistor 23 is formed by sputtering or the like. Thereafter, the electrode 28 is patterned by etching so as to extend along the resistor 23 with a gap positioned on the slope of the protrusion 21 interposed therebetween.

  After step S4, a protective layer 29 that covers the heat insulating layer 25, the resistor 23, and the electrode 28 is formed (S5). Step S5 is referred to as a protective layer forming step. At this time, the thickness of the protective layer 29 is substantially uniform throughout.

  FIG. 5 is a partial cross-sectional view of the heating element plate after the protective layer forming step in the present embodiment.

  The surface of the protrusion 21 portion of the heat insulating layer 25 substantially forms an arc in a cross section perpendicular to the main scanning direction. For this reason, after the protective layer forming step (S5), the surface of the protective layer 29 draws an arc 78 in the vicinity of the heat generating region 24 in a cross section perpendicular to the main scanning direction. That is, at this time, when the position in the sub-scanning direction is different in the vicinity of the heat generating region 24, the normal line on the surface of the protective layer 29 is in a different direction. In addition, since the electrode 28 existing before and after in the sub-scanning direction does not exist in the heat generation region 24, a recess 79 is formed on the surface of the protective layer 29 in a portion corresponding to the heat generation region 24. There is also.

  Therefore, next, the plate on which the protective layer 29 is formed is cut in the plate thickness direction by dicing or the like, and divided into a plurality of heating element plates 20 (S6), that is, the direction across the protrusion 21 of the protective layer 29, that is, A region having a predetermined length before and after the heat generating region 24 in the sub-scanning direction is polished flatly (S7). Step S5 is referred to as a polishing step. Thereby, the flat part 71 is formed in the protective layer 29. In the polishing step (S7), the size of the flat portion 71 is appropriately set with respect to the thickness of the protective layer 29 so that the electrode 28 and the resistor 23 are not polished and the protective layer 29 is not excessively thinned. Set.

  FIG. 6 is a partial cross-sectional view of the heating element plate during the polishing step in the present embodiment.

  In the polishing step (S 7), the lower surface of the heating plate 20, that is, the lower surface of the insulating plate 22 is placed on a flat work table 80, and the surface of the protective layer 29 is polished with a polishing tool 81. The polishing tool 81 includes a flat surface 82 and a polishing surface 83. The polishing surface 83 is a flat surface that forms a predetermined angle with the flat surface 82, and is formed of an abrasive material that is harder than the protective layer 29, for example, by attaching a silicon carbide (SiC) polishing film or the like.

  By pressing the flat surface 82 of the polishing tool 81 against the surface of the work table 80, the polishing surface 83 of the polishing tool 81 can be at a constant angle with the surface of the work table 80. In this state, the polishing tool 81 is moved in the longitudinal direction of the heat generating plate 20, that is, the direction in which the heat generating region 24 extends, and the protective layer 29 is polished. Accordingly, the surface of the protective layer 29 can be polished while the angle of the polishing surface 83 is set to a predetermined angle with respect to the lower surface of the insulating plate 22 serving as a reference surface.

  The heating plate 20 thus formed is placed on the heat sink 30 together with the circuit board 40 (S8). Further, the thermal print head 10 is manufactured by connecting the heating element plate 20 and the circuit board 40 with the bonding wire 44 (S9), and further sealing the connection portion with the bonding wire 44 with the resin 48 (S10). .

  The thermal print head 10 formed in this way has a flat portion 71 having a predetermined angle with respect to the lower surface of the insulating plate 22. The surface of the heat radiating plate 30 on which the heat generating plate 20 is placed is formed in parallel, and the lower surface of the heat generating plate 20 is parallel to the surface of the heat radiating plate 30 on which the heat generating plate 20 is placed. By fixing the heat generating plate 20 to the heat radiating plate 30, the flat portion 71 of the protective layer 29 forms a predetermined angle with the lower surface of the heat radiating plate 30.

  The thermal print head 10 is placed on the fixing surface 56 of the fixing base 54 of the thermal printer and fixed with screws 55. In this way, the position of the thermal print head 10 in the thermal printer is determined.

  Since the heat insulating layer 25 is formed by baking glass, for example, the cross-sectional shape of the heat insulating layer 25 varies to some extent. In the thermal print head 10 according to the present embodiment, the heat generating region 24 is arranged on the opposite side of the driver IC across the apex of the heat insulating layer 25 formed on the protrusion 21, and the heat generating region 24 is arranged at the end of the heat generating plate 20. It is a near edge structure provided in the immediate vicinity. For this reason, even if the resistor 23 and the electrode are laminated at a predetermined position of the heat retaining layer 25 to form the heat generating region 24, there is some variation in the normal direction and tangential direction of the surface of the protective layer 29 in the heat generating region 24. Will occur.

  Further, even when the resistor 23 and the electrode 28 are formed on the surface of the heat insulating layer 25, a certain amount of positional deviation is unavoidable, and a certain degree of variation occurs in the position where the heat generating region 24 is formed. For this reason, even if the cross section of the surface of the protective layer 29 of the heating element plate 20 draws an arc having a predetermined shape, there is some variation in the normal direction / tangential direction of the surface of the protective layer 29 in the heat generating region 24. It will occur.

  In order to obtain a predetermined printing accuracy, the platen roller 50 needs to be positioned within a predetermined width from the tangential direction of the surface of the protective layer 29 in the heat generating region 24. When there are variations in the normal direction and tangential direction of the surface of the protective layer 29 in the heat generating region 24, the positioning of the platen roller 50 is very difficult. In such a case, for example, if the thermal print head 10 is movable only along the reference surface 56 of the fixed base 54, the platen roller 50 moves in at least two directions: a direction parallel to the reference surface 56 and a direction perpendicular thereto. Need to be positioned. Alternatively, if the platen roller 50 can move only in one direction, the thermal print head 10 cannot be positioned unless it is tilted with respect to the fixed base 54.

  However, in the present embodiment, it is ensured that the normal direction / tangential direction of the surface of the protective layer 29 in the heat generating region 24 is a constant angle with a predetermined accuracy with respect to the reference surface 56 of the fixed base 54. . Therefore, even if the thermal print head 10 can move only along the reference surface 56 of the fixed base 54, it can be positioned by moving the platen roller 50 only in one direction.

  As described above, in the present embodiment, the thermal print head 10 having the near edge structure can be easily attached to the thermal printer.

  Further, even when the depression 79 is formed on the surface of the protective layer 29 when the protective layer 29 is formed, the surface of the protective layer 29 can be planarized by polishing. For this reason, the to-be-printed medium 60 contacts the surface of the thermal print head 10 better, and heat transfer characteristics are improved.

  A harder wear-resistant layer may be provided on the surface of the protective layer 29. In this case, it is possible to form the flat portion by polishing after forming the wear-resistant layer, but it is easier to polish the protective layer 29 which is softer than the wear-resistant layer.

[Second Embodiment]
FIG. 7 is a partial cross-sectional view of a heat generating plate in the second embodiment of the thermal print head according to the present invention.

  In the heat generating plate 20 of the thermal print head of the present embodiment, the protrusion 21 of the heat insulating layer 25 is provided in a band shape with a predetermined width in contact with the edge of the insulating plate 22. The protrusion 21 is a part of the heat insulating layer 25 that protrudes from the main surface of the insulating plate 22 to the top 74 that extends along the edge of the insulating plate 22. Slopes 75 and 76 are formed on both sides of the top portion 74 of the ridge 21, that is, from the linear top portion 74 toward the upstream side and the downstream side in the sub-scanning direction. In the cross section cut perpendicularly to the main scanning direction, a part of the surface of the protrusion 21 forms an arc.

  A flat portion 72 is formed in a part of the slope 75 of the protrusion 21 of the heat retaining layer 25 and in the vicinity of the heat generating region 24. In the cross section cut perpendicular to the main scanning direction, the slope 75 forms an arc in a region other than the flat portion 72. The flat portion 72 occupies a region of a predetermined length before and after the heat generating region 24 in a direction crossing the ridge 21, that is, in the sub-scanning direction. The thickness of the protective layer 29 is substantially constant regardless of the position in the sub-scanning direction. Therefore, a flat portion 71 is also formed on the surface of the protective layer 29 in the vicinity of the heat generating region 24.

  In such a thermal print head, the polishing step (S7) in the first embodiment is performed after the heat insulating layer forming step (S3). In the present embodiment, the heat retaining layer 25 is polished to form the flat portion 72 in the polishing step. If the substrate is divided before the heat insulating layer 25 is polished, the polishing becomes easier.

  Also in this embodiment, after the protective layer 29 is formed, the surface of the protective layer 29 may be further polished. Thereby, the normal direction / tangential direction of the surface of the protective layer 29 in the heat generating region 24 can be more accurately formed. In some cases, the surface of the protective layer 29 has a depression formed in a portion corresponding to the heat generating region 24. However, by polishing the surface of the protective layer 29, even if a depression is formed on the surface of the protective layer 29 when the protective layer 29 is formed, the surface of the protective layer 29 can be planarized by polishing. For this reason, the to-be-printed medium 60 contacts the surface of the thermal print head 10 better, and heat transfer characteristics are improved.

  Also in the present embodiment, the normal direction and the tangential direction of the surface of the protective layer 29 in the heat generating region 24 are constant with a predetermined accuracy with respect to the reference surface 56 (see FIG. 3) of the fixing base 54 (see FIG. 3). Guaranteed to be an angle. Therefore, the near-edge structure thermal print head 10 (see FIG. 3) can be easily attached to the thermal printer.

  There is no need to polish the protective layer 29 for planarization, and there is no possibility of polishing the electrode 28 or the resistor 23. Further, the thickness of the protective layer 29 is constant, that is, the protective layer 29 is not thin in the vicinity of the heat generating region 24 that is in contact with the printing medium 60. For this reason, there is no possibility that the electrode 28 or the resistor 23 is shaved by polishing the protective layer 29. Abrasion resistance is improved.

[Third Embodiment]
FIG. 8 is a partial sectional view of a heating plate in the third embodiment of the thermal print head according to the present invention.

In the present embodiment, a small ridge 90 extending in the same direction as the ridge 21 is provided in a portion corresponding to the heat generating region 24 of the heat retaining layer 25. The small protrusions 90 are formed of silicon oxide (SiO ₂ ) in the same manner as the protrusions 21.

  In this embodiment, in the heat insulation layer forming step (S3) in the second embodiment, the small protrusions 90 are formed by pattern printing and baking a glass paste on the corresponding portions. Alternatively, after the large protrusions 21 are formed by firing, the glass protrusions may be further printed and then fired again to form the small protrusions 90. The surface of the small protrusion 90 after firing has a shape in which the cross section draws an arc. Therefore, in the polishing step, the flat portion 73 is formed on the surface of the small protrusion 90 by polishing the surface of the small protrusion 90 with the polishing tool 81 (see FIG. 6).

  Also in the present embodiment, the normal direction and the tangential direction of the surface of the protective layer 29 in the heat generating region 24 are constant with a predetermined accuracy with respect to the reference surface 56 (see FIG. 3) of the fixing base 54 (see FIG. 3). Guaranteed to be an angle. Therefore, the near-edge structure thermal print head 10 (see FIG. 3) can be easily attached to the thermal printer. Further, since the thickness of the protective layer 29 is constant, that is, the protective layer 29 is not thin in the vicinity of the heat generating region 24 in contact with the printing medium, the wear resistance performance is improved.

  Further, in this embodiment, since the polishing portion of the heat retaining layer 25 is limited to the portion of the small protrusion 90, the polishing area is smaller than that in the second embodiment, so the time required for polishing can be reduced. Cost can be reduced. Further, in the vicinity of the small protrusions 90, since it has a convex cross-sectional shape toward the platen roller 50 (see FIG. 3), the printing medium 60 is in close contact with the surface of the thermal print head 10 in the vicinity of the heat generating region 24. Thus, heat transfer characteristics are improved.

[Other embodiments]
The above-described embodiments are merely examples, and the present invention is not limited to these. Moreover, it can also implement combining the characteristic of each embodiment.

DESCRIPTION OF SYMBOLS 10 ... Thermal print head, 20 ... Heat generating body board, 21 ... Projection, 22 ... Insulating board, 23 ... Resistor, 24 ... Heat generating area, 25 ... Heat insulation layer, 28 ... Electrode, 29 ... Protective layer, 30 ... Heat sink , 40 ... Circuit board, 42 ... Driver IC, 44 ... Bonding wire, 48 ... Resin, 50 ... Platen roller, 52 ... Shaft, 54 ... Fixing base, 55 ... Screw, 56 ... Reference plane, 60 ... Print medium, 70 ... normal direction, 71 ... flat part, 72 ... flat part, 73 ... flat part, 74 ... top part, 75, 76 ... slope, 78 ... arc, 79 ... depression, 80 ... work table, 81 ... polishing tool, 82 ... Flat surface, 83 ... polished surface, 90 ... small protrusion

Claims (5)

An insulating substrate having an insulating plate and a heat insulating layer provided on the main surface of the insulating plate in contact with the edge of the main surface and extending in a strip shape and having a ridge formed with slopes on both sides of the top portion;
A plurality of resistors arranged at intervals in the direction in which the protrusions extend on the slope closer to the edge, and a heat generation region located on the slope closer to the edge on the surface of the resistor A wiring layer provided with electrodes provided opposite to each other,
A protective layer that covers the insulating substrate, the resistor, and the electrode, and that has a surface region of a predetermined length before and after the heat generating region in a direction crossing the protrusion, and is formed flat;
A thermal print head comprising:   2. The thermal print head according to claim 1, wherein a surface region having a predetermined length before and after the heat generating portion is formed flat in a direction across the protrusions in the heat insulating layer.   The heat retaining layer includes a small protrusion that protrudes from the slope closer to the edge of the protrusion to the wiring layer side and extends in the same direction as the protrusion, and a part of the surface of the small protrusion is flat. 3. The thermal print head according to claim 2, wherein the heat generating area is formed in a flat portion of the small protrusion. Forming an insulating substrate having an insulating plate and a heat insulating layer provided on the main surface of the insulating plate with a protrusion extending in a belt shape and in contact with an edge of the main surface and having slopes formed on both sides of the top portion; ,
A slope closer to the edge of the ridge on the surface of the resistor and a plurality of resistors arranged at intervals in the direction in which the ridge extends in a slope closer to the edge of the ridge Forming a wiring layer provided with electrodes provided opposite to each other across the heat generation region located at
A protective layer forming step of forming a protective layer covering the insulating substrate, the resistor, and the electrode;
A flat portion is formed by polishing a region of a predetermined length in a direction crossing the ridge of the slope closer to the edge of the ridge of the protective layer at a predetermined angle with respect to the main surface of the insulating plate. A protective layer polishing step to be formed;
A method of manufacturing a thermal print head, comprising: Forming an insulating substrate having an insulating plate and a heat insulating layer provided on the main surface of the insulating plate with a protrusion extending in a belt shape and in contact with an edge of the main surface and having slopes formed on both sides of the top portion; ,
A flat portion is formed by polishing a region of a predetermined length in a direction crossing the protrusion on the slope closer to the edge of the protrusion of the heat retaining layer at a predetermined angle with respect to the main surface of the insulating plate. Forming, and
A plurality of resistors arranged at intervals in the direction in which the ridges extend in the flat portion, and a surface of the resistor across the heating region located on the slope closer to the edge of the ridges Forming a wiring layer including an electrode provided as
Forming a protective layer covering the insulating substrate, the resistor and the electrode;
A method of manufacturing a thermal print head, comprising:

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