JP2010253739A - Thermal print head and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress occurrence of scratch on print when using a thermal print head of a near edge structure. <P>SOLUTION: The heating element plate 20 of the thermal print head includes: an insulation substrate having an insulation plate 22 and a heat reserving layer 25 on the insulation plate 22; resistors 23, an electrode 28, and a protective layer 29. The temperature reserving layer 25 has a projection 21 extending so that its one edge overlaps the surface of the end edge 70 of the main surface of the insulation plate 22. The resistor 23 are disposed on a sloping surface near the end edge 70 of the projection 21 interspatially in a main scanning direction. The electrode 28 is disposed opposite the surface of the register 23 with a clearance 71 left between them, the clearance 71 being located in the inclining surface near the end edge 70 of the projection 21. The protective layer 29 covers the temperature reserving layer 25, register 23, and electrode 28. The protective layer 29 has a thick layer portion 73 and a thin layer portion 72. The thin layer portion 72 extends between a boundary line 74, located closer to the clearance 71 than to the end edge 70, and the end edge 70. The thick layer portion 73 extends toward the clearance 71 from the boundary line 74. <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.

  In some cases, a near-edge structure is employed so that the printing medium does not interfere with the resin that protects 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). ).

Japanese Patent Application No. 2005-262828

  When a heat generating plate is manufactured by cutting out from a large plate, scratches such as chipping may occur at the end of the heat generating plate during dicing of the heat generating plate. When such a scratch comes into contact with the printing medium, a print scratch may occur during printing.

  In a thermal printing head having a near-edge structure in which a heat generating area is arranged on the opposite side of the driver IC across the ridge line of the heat insulating layer formed on the ridge, the heat generating area is provided very close to the end of the heat generating plate. For this reason, particularly in the case of a thermal print head having a near-edge structure, the printing medium is likely to come into contact with the end portion of the heating plate, and print damage is likely to occur.

  SUMMARY An advantage of some aspects of the invention is that it suppresses the occurrence of print defects when a near-edge thermal printhead is used.

  In order to solve the above-described problems, the present invention provides a thermal printhead, wherein the insulating plate is formed in a shape having a protrusion extending so that one side overlaps an edge of a main surface of the insulating plate. A heat insulating layer provided on an insulating plate; and an insulating substrate, and a plurality of resistors arranged at intervals in a direction in which the ridge extends on a slope closer to the edge of the ridge, Covering the electrode provided opposite to the surface of the resistor across the gap located on the slope closer to the edge of the ridge, the insulating substrate, the resistor, and the electrode, the gap And a protective layer having a layer thickness part that extends to the boundary line on the edge side and a thin layer part that is thinner than the layer thickness part that covers between the edge and the boundary line. Features.

  According to the present invention, in the method for manufacturing a thermal print head, a first step of forming a heat insulating layer having a ridge on the surface of the insulating plate, and the ridge on the slope of the ridge after the first step. A second step of arranging the resistors at intervals in the extending direction of the resistor, and a third step of providing, on the surface of the resistor, electrodes opposed to each other with a gap positioned on the slope of the ridge after the second step. After the step and the third step, the layer thickness portion extending from the top line of the ridge to the boundary farther than the gap, and the layer thickness portion extending to the opposite side of the layer thickness portion with respect to the boundary line A fourth step of covering the insulating substrate, the resistor, and the electrode with a protective layer having a thin layer portion, and the insulating substrate, the heat retaining layer, and the protective layer in the thin layer portion. And a fifth step of cutting in the thickness direction.

  According to the present invention, it is possible to suppress the occurrence of print damage when a thermal print head having a near edge structure is used.

It is a fragmentary sectional view of the heat generating body board in one embodiment of the thermal print head concerning the present invention. FIG. 2 is a partially cut-out top view of an embodiment of a thermal print head according to the present invention. 1 is a cross-sectional view of a part of a thermal printer using an embodiment of a thermal print head according to the present invention. It is a flowchart of the manufacturing method in one Embodiment of the thermal print head which concerns on this invention.

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

  FIG. 1 is a partial cross-sectional view of a heating element plate in an embodiment of a thermal print head according to the present invention. FIG. 2 is a partially cutaway top view of the thermal print head in the present embodiment. FIG. 3 is a cross-sectional view of a part of a thermal printer using the thermal print head of the present embodiment.

  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. 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 platen roller 50 formed in a cylindrical shape with a material having a predetermined elasticity. The platen roller 50 has a shaft 52 on a straight line parallel to the main scanning direction. Further, the side surface of the platen roller 50 is disposed so as to be in contact with the heat generating region 24, and is provided so as to be rotatable about the shaft 52.

  Due to the rotation of the platen roller 50, the thermal recording 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 thermal recording medium 60 is, for example, thermal paper that develops color when heated to a color development temperature or higher. While the thermal recording medium 60 is pressed against the heat generating area 24 by the platen roller 50, the thermal recording medium 60 is moved in the sub-scanning direction, and the heat generation pattern of the heat generating area 24 is changed along with the movement of the thermal recording medium 60. An image is formed on the thermal recording medium 60.

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 the heat retaining layer 25. The protrusion 21 is provided in contact with the end edge 70 of the insulating plate 22.

  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 70 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. Further, the electrodes 28 are provided to face each other with a gap 71 extending in a direction in which the resistor located on the slope closer to the end edge 70 of the protrusion 21 extends. Since the current flowing through the electrode 28 passes through the resistor 23 in the gap 71, the portion corresponding to the gap 71 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 70 of the insulating plate 22 extends, that is, in the main scanning direction, and 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 protrusion 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 almost entirely formed with substantially the same thickness, but a thin layer portion 72 having a small thickness is formed in part. That is, the protective layer 29 has a layer thickness portion 73 and a layer thin portion 72 thinner than the layer thickness portion 73. A boundary line 74 between the layer thickness portion 73 and the layer thin portion 72 extends in a direction in which the protrusion 21 extends at a position closer to the edge 70 than the gap 71 provided between the electrodes 28, that is, the heat generation region 24. . The edge 70 side of the boundary line 74 is a thin layer portion 72, and the heat generation region 24 side of the boundary line 74 is a layer thickness portion 73. The thickness of the layer thickness portion 73 is approximately 5 μm, and the thickness of the layer thin portion 72 is approximately 3 μm.

  If the boundary line 74 between the layer thickness portion 73 and the layer thin portion 72 has a corner, a print defect may occur when the thermal recording medium 60 contacts the corner. Therefore, it is preferable that the thickness of the protective layer 29 is continuously changed at the boundary line 74 between the layer thickness portion 73 and the layer thin portion 72. That is, it is preferable that the surface of the protective layer 29 has a smooth curve at the boundary line 74 between the layer thickness portion 73 and the layer thin portion 72. In order to say that the boundary line 74 between the layer thickness part 73 and the layer thin part 72 is not substantially angular, the radius of curvature of the surface of the protective layer 29 at this boundary is required to be 1 μm or more.

  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 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. At this time, the raised portions corresponding to the ridges 21 of the two heating element plates 20 are arranged so that the portions corresponding to the thin layer portion 72 of the protective layer 29 face each other.

  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.

  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 71 positioned on the slope of the ridge 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). At this time, the thickness of the protective layer 29 is set to a thickness corresponding to the layer thickness portion 73 uniformly throughout. Thereafter, the thickness of the portion corresponding to the thin layer portion 72 is reduced by etching or the like (S6). Here, after covering the whole with the thickness corresponding to the layer thickness portion 73, the thickness of the portion corresponding to the layer thin portion 72 is decreased, but first, the entire thickness with the thickness corresponding to the layer thin portion 72 is reduced. After covering, the layer thin part 72 may be masked to increase the thickness of the layer thick part 73.

  Next, the plate on which the protective layer 29 is formed is cut in the thickness direction by dicing or the like, and divided into a plurality of heating element plates 20. Since the portions corresponding to the thin layer portions 72 of the two heating element plates 20 are arranged so as to face each other, the thin layer portions 72 are diced.

  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). .

  As described above, when the thermal print head 10 is manufactured, scratches such as chipping may occur at the end of the protective layer 29 due to dicing when the heating plate 20 is divided. However, in this embodiment, since the thin layer portion 72 of the protective layer 29 is provided downstream of the heat generating area 24 in the transport direction of the thermal recording medium 60, the downstream protection in the transport direction of the thermal recording medium 60 is provided. The end of the layer 29 is located below the tangent to the surface of the protective layer 29 in the heat generating region 24. For this reason, when the thermal recording medium 60 is conveyed linearly as in the case of printing on the hard thermal recording medium 60 or the like, the thermal recording medium 60 is unlikely to contact the end portion of the protective layer 29.

  Therefore, even if there is a scratch such as a chip at the end of the protective layer 29, the occurrence of a print defect can be suppressed. In addition, since some scratches are allowed at the end portion of the protective layer 29, an operation such as polishing of the end portion is unnecessary after dicing when the heating plate 20 is divided.

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, 60 ... thermal recording medium, 70 ... edge, 71 ... gap, 72 ... layer thin part, 73 ... layer thickness part, 74 ... boundary line

Claims (3)

An insulating substrate having an insulating plate and a heat insulating layer formed on the insulating plate and formed in a shape having a ridge extending so that one side of the insulating plate overlaps an edge of the main surface of the insulating plate;
A plurality of resistors arranged at intervals in the direction in which the ridges extend on the slope closer to the edge of the ridges;
An electrode provided facing the surface of the resistor across a gap located on the slope closer to the edge of the ridge,
A layer thickness portion that covers the insulating substrate, the resistor, and the electrode and extends to a boundary line on the edge side with respect to the gap, and a layer thickness portion that covers a space between the edge and the boundary line. A protective layer with a thin layer,
A thermal print head comprising:   The thermal print head according to claim 1, wherein the thickness of the protective layer continuously changes at the boundary line. A first step of forming a heat insulating layer having protrusions on the surface of the insulating plate;
After the first step, a second step of arranging the resistors with an interval in the direction in which the ridge extends on the slope of the ridge, and
A third step of providing, on the surface of the resistor, electrodes facing each other with a gap located on the slope of the ridge after the second step;
After the third step, the layer thickness portion that extends to the boundary line farther from the top line of the ridge than the gap, and the layer thickness portion that extends on the opposite side of the layer thickness portion with respect to the boundary line, is thicker than the layer thickness portion. A fourth step of covering the insulating substrate, the resistor and the electrode with a protective layer having a thin layer thin section;
A fifth step of cutting the insulating substrate, the heat retaining layer, and the protective layer in the thickness direction at the thin layer portion;
A method of manufacturing a thermal print head, comprising:

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