JP2014200954A - Thermal print head and thermal printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress temperature lowering of the more downstream side than a heating area in a thermal print head of a near edge structure.SOLUTION: A thermal print head includes an insulation plate 22, a heat insulation layer 25, a resistance body 23, an electrode 28, and a protection layer 29. The insulation plate 22 is rectangular and an inclination plane 72 is formed with contacting to the long side 73 of one side. The heat insulation layer 25 is formed as such a shape that has a protruding strip 21 extending so that one side superimposes on the long side 73 of the insulation plate 22 on the insulation plate. The resistance body 23 is aligned with a spacing in the direction of extending of the protrusion strip 21 in the inclination plane which is nearer to the long side 73 of the protrusion strip 21. The electrode 28 is provided with a spacing 71 positioning the inclination plane which is nearer to the long side 73 of the protrusion strip 21 on the surface of the resistance body 23 as facing to the resistance body 23. The protection layer 29 covers the heat insulation layer 25, the resistance body 23 and the electrode 28.

Description

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

  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 top of the glaze layer formed on the surface of the ceramic plate, and the heat generating region is provided very close to the end of the heat generating plate.

JP 2005-262828 A

  In a near-edge structure thermal print head 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, a glaze layer formed on the ridge is provided on the surface of the ceramic plate. The heat generation region is provided on the end side of the ridge, that is, on the downstream side of the ridge line at the top of the ridge in the conveyance direction of the print medium. For this reason, in the case of the near edge structure, if the glaze layer protrusion is provided on the surface of the ceramic plate having a flat surface, the thickness of the glaze layer, which is the heat retaining layer on the downstream side with respect to the heat generation region, is larger than that of the upstream side Become thinner. When the heat insulating layer becomes thin, the temperature of the surface of the heating element plate is lowered. As a result, the printing medium may be damaged or energy efficiency may be deteriorated.

  Accordingly, an object of the present invention is to suppress a decrease in temperature downstream of the heat generation region in the near-edge structure thermal print head.

  In order to solve the above-described problems, the present invention provides a thermal print head in which a rectangular insulating plate having a thin plate thickness in contact with one long side is overlapped with the one side on the long side. An insulating substrate having a heat insulating layer formed on the insulating plate and formed in a shape having a protruding ridge, and spaced in a direction in which the protruding ridge extends on a slope closer to the edge of the protruding ridge. A plurality of resistors arranged with a gap therebetween, electrodes provided facing the surface of the resistor across a gap located on the slope closer to the edge of the ridge, and the insulating substrate And a protective layer covering the resistor and the electrode.

  Further, the present invention provides a thermal printer having a rectangular shape with an insulating plate formed in contact with one long side and having a thin plate thickness, and a protrusion extending so that one side overlaps the long side. And a heat insulating layer formed on the insulating plate, and a plurality of the insulating substrates arranged at intervals in a direction in which the ridges extend on a slope closer to the edge of the ridges. A resistor, an electrode provided on the surface of the resistor so as to oppose the gap located on the slope closer to the edge of the ridge, the insulating substrate, the resistor, and the electrode A thermal printing head having a protective layer, and a platen roller having an axis parallel to the direction in which the heating resistors are arranged and located in a normal direction in the region in which the resistors are arranged. It is characterized by comprising.

  According to the present invention, in the thermal print head having a near edge structure, it is possible to suppress a temperature decrease downstream of the heat generation area.

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 cut-out top view of a thermal print head according to a first embodiment of 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 fragmentary sectional view of the heat generating body board in 2nd Embodiment of the thermal print head concerning this invention.

  Several embodiments 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.

[First Embodiment]
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 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 generation 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 generation 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 a rectangular plate formed of an insulator such as alumina (Al ₂ O ₃ ). The surface on the one long side 73 side of the insulating plate 22 is shaved to form a slope 72.

The heat insulating layer 25 is formed on the surface of the insulating plate 22 by, for example, silicon oxide (SiO ₂ ). Further, a protrusion 21 is formed on the heat retaining layer 25. The ridge 21 is provided in a region including the inclined surface 72 in contact with one long side 73 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 long side 73 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, aluminum. The electrodes 28 are provided to face each other with a gap 71 extending in the direction in which the resistor located on the slope closer to the long side 73 of the ridge 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. This heat generating portion is arranged at intervals in the direction in which the long side 73 of the insulating plate 22 extends, that is, in the main scanning direction, and forms a heat generating region 24 extending in the main scanning direction.

  As described above, the thermal print head 10 of 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 boundary between the inclined surface 72 and the flat portion of the insulating plate 22 is located in the normal direction 80 in the heat generating region 24. The angle formed between the normal direction 80 and the slope 72 is equal to the angle formed between the normal direction and the flat portion of the insulating plate 22.

  Next, a method for manufacturing a thermal print head will be described.

  First, an insulating plate is formed from ceramic. The insulating plate has such a size that a plurality of finally produced heating element plates 20 are cut out. Next, a groove corresponding to the inclined surface 72 is formed on the insulating plate with a dicer or the like.

  Thereafter, a glass paste is pattern-printed on the insulating plate. 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 fired. 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. 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 the resistor 23 and the electrode 28 are formed, a protective layer 29 that covers the heat insulating layer 25, the resistor 23, and the electrode 28 is formed.

  Next, the plate on which the protective layer 29 is formed is cut in the plate thickness direction at the bottom of the groove corresponding to the inclined surface 72 by dicing or the like, and divided into a plurality of heating element plates 20.

  The heating plate 20 thus formed is placed on the heat sink 30 together with the circuit board 40. In addition, the thermal print head 10 is manufactured by connecting the heating element plate 20 and the circuit board 40 with the bonding wires 44 and sealing the connecting portion with the bonding wires 44 with the resin 48.

  Although such a thermal print head 10 has a near edge structure, since the slope 72 is provided at the end of the insulating plate 22, the thickness of the heat insulating layer on the downstream side of the heat generating region 24 does not decrease so much. For this reason, the decrease in the surface temperature of the heat generating plate 20 on the downstream side of the heat generating region 24 is not so large as compared with the upstream side. Therefore, even if the thermal print head has a near edge structure, it is possible to suppress a temperature decrease downstream of the heat generating region 24.

  In the present embodiment, the boundary line between the inclined surface 72 and the flat portion of the insulating plate 22 is positioned in the normal direction of the heat generating region 24. The angle formed between the normal direction 80 and the slope 72 is equal to the angle formed between the normal direction and the flat portion of the insulating plate 22. For this reason, in a certain area, the thicknesses of the heat retaining layers on the upstream side and the downstream side are symmetric with respect to the heat generating region 24. For this reason, the temperature distribution on the surface of the heating element plate 20 on the upstream side and the downstream side with respect to the heating area 24 becomes nearly symmetrical.

  In this way, by cutting the end portion of the insulating plate 22 of the thermal print head, the thickness of the heat insulating layer can be changed, and an optimum temperature distribution can be obtained.

[Second Embodiment]
FIG. 4 is a partial sectional view of a heating plate in the second embodiment of the thermal print head according to the present invention.

  In the present embodiment, the surface on the one long side 73 side of the insulating plate 22 is scraped to form a flat portion 74 and a step 75 that are thin. Also in such a thermal print head, the thickness of the heat insulating layer on the downstream side of the heat generating region 24 is larger than in the case where an insulating plate having a flat surface as a whole is used. For this reason, the decrease in the surface temperature of the heat generating plate 20 on the downstream side of the heat generating region 24 is not so large as compared with the upstream side. Therefore, even if the thermal print head has a near edge structure, it is possible to suppress a temperature decrease downstream of the heat generating region 24.

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, 71 ... Gap, 72 ... Slope, 73 ... Long side, 74 ... Flat part, 75 ... step, 80 ... normal direction

Claims (5)

An insulating plate that is rectangular and has a thin part in contact with one long side, and a protrusion that extends so that one side overlaps the long side and is provided on the insulating plate An insulating substrate having a thermal insulation layer,
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 protective layer covering the insulating substrate, the resistor, and the electrode;
A thermal print head comprising:   The thermal print head according to claim 1, wherein the thin plate portion is a slope contacting the long side.   3. The thermal print head according to claim 2, wherein a boundary between the inclined surface and the flat portion is located in a normal direction of the insulating substrate in a region where the resistors are arranged.   The thermal print head according to claim 3, wherein an angle formed between the inclined surface and the normal line direction is substantially equal to an angle formed between the flat portion and the normal line direction. An insulating plate that is rectangular and has a thin part in contact with one long side, and a protrusion that extends so that one side overlaps the long side and is provided on the insulating plate A plurality of resistors arranged at intervals in the direction in which the ridges extend on the slope closer to the end edge of the ridges, and the surfaces of the resistors And a protective layer that covers the insulating substrate, the resistor, and the electrode, and an electrode provided opposite to the gap located on the slope closer to the edge of the ridge. Head,
A platen roller located in a normal direction in the region in which the resistors are arranged and having an axis parallel to the direction in which the heating resistors are arranged;
A thermal printer comprising:

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