JP2014069377A - Thermal printer and thermal printhead for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a folded type thermal printhead which enhances uniformity of an overcoat while improving gradation expression power.SOLUTION: A thermal printhead is provided with heat-resistant elements 91, 92, 93 and 94 arrayed in a main scanning direction. The four heat-resistant elements 91, 92, 93 and 94 constitute one set, and the heat-resistant elements 92 and 93 on the inside are connected by a first folded electrode 81. The heat-resistant elements 91 and 94 on the outside are connected by a second folded electrode 82. The heat-resistant elements 91 and 94 on the outside are provided with intermediate electrodes 12 and 14 disposed in the middle and are divided into three portions.

Description

  The present invention relates to a thermal printer that prints on a print medium and overcoats a print screen, and a thermal print head used therefor.

  Thermal print heads are attracting attention as output devices such as video printers, imagers, and seal printers. The thermal print head records on thermal paper, plate-making film photographic paper, media, etc. by generating heat from a heating resistor disposed on a support substrate having a heat insulating layer. Since thermal print heads have advantages such as low noise and low running cost, various developments have been made.

  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. A plurality of heating resistors are linearly arranged at predetermined intervals in a heating region extending in a band shape on the surface opposite to the surface of the heating plate opposite to the heat sink. The circuit board is mounted with electrical components such as a drive IC that is a part of a drive circuit that drives the heating resistor.

  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 generating area on the support substrate with the main scanning direction in which the heat generating resistors are arranged as an axis, and is provided rotatably 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 resistance is changed with the movement of the medium, thereby forming a desired image on the medium.

  In a thermal printer, for example, a single type that is electrically connected to one end of all the heating resistors and each heating resistor draws one pixel, and two heating resistors that are connected by folded electrodes There is a folding type (see, for example, Patent Document 1) in which one pixel is drawn.

JP 2008-168485 A JP 2012-076417 A

  In the folded-type thermal print head, a gap is required between two heat generating resistors that draw one pixel, so that heat is diffused as compared with the single type, and the peak temperature in the heat generating portion is lowered. For this reason, a melt-type thermal printer may have poor efficiency and response.

  In order to improve the efficiency and response to the level of a single type, it is effective to bring the heating resistor that draws the same pixel toward the center of the pixel. However, this method increases the distance between adjacent pixels, and it is difficult to ensure uniformity during overcoating.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve the uniformity of an overcoat while improving the gradation expression power in a folded-type thermal print head.

  In order to solve the above-described problems, the present invention relates to an insulating substrate and a surface of the insulating substrate arranged at intervals in a thermal print head used in a thermal printer that prints on a printing medium and overcoats a printing screen. The plurality of heating resistors and the plurality of heating resistors are repeatedly arranged in the arrangement direction with the first heating resistor, the second heating resistor, the third heating resistor, and the fourth heating resistor. A first folded electrode that connects the second heating resistor and the third heating resistor, and one of the second heating resistor and the third heating resistor opposite to the first folded electrode. A first electrode connected on the side, a second folded electrode connecting the first heating resistor and the fourth heating resistor, and any one of the first heating resistor and the fourth heating resistor Second fold A second electrode connected on the opposite side of the first electrode, and connected to the first electrode and the second electrode to heat the second heating resistor and the third heating resistor during printing, And a driving element that generates heat from all of the heating resistors, wherein the first heating resistor and the fourth heating resistor are divided in the transport direction of the printing medium.

  The present invention also relates to a thermal printer that prints on a printing medium and overcoats a print screen, and includes an insulating substrate, a plurality of heating resistors arranged at intervals on a surface of the insulating substrate, and the plurality of heating resistors. The second heating resistor when the first heating resistor, the second heating resistor, the third heating resistor, and the fourth heating resistor are classified as being repeatedly arranged in the arrangement direction. A first folded electrode connecting the third heating resistor, a first electrode connected to one of the second heating resistor and the third heating resistor on the opposite side of the first folded electrode; A second folded electrode that extends along the first folded electrode and connects the first heating resistor and the fourth heating resistor; and one of the first heating resistor and the fourth heating resistor. The second folded electrode A second electrode connected on the side, a driving element connected to the first electrode and the second electrode and generating heat from the heating resistor, and a conveying means for conveying the printing medium, The first heating resistor and the fourth heating resistor are divided in the transport direction of the printing medium.

  According to the present invention, it is possible to improve the uniformity of the overcoat while improving the gradation expression with a folded thermal print head.

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 partially enlarged cross-sectional view of a first embodiment of a thermal print head according to the present invention. 1 is a perspective view of a first embodiment of a thermal print head according to the present invention. It is sectional drawing of the thermal printer using 1st Embodiment of the thermal print head concerning this invention. It is a partially cutaway top view in the second embodiment of the thermal print head according to the present 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. 1 is a partially cut-out top view of a first embodiment of a thermal print head according to the present invention. FIG. 2 is a partially enlarged sectional view of the thermal print head according to the present embodiment. FIG. 3 is a perspective view of the thermal print head according to the present embodiment.

  The thermal print head 10 according to the present embodiment includes a heat dissipation board 20, a heating element plate 30, a circuit board 41, and a drive element 42. The heat dissipation substrate 20 is a plate formed of a material having a high thermal conductivity such as aluminum.

  The heating element plate 30 has an insulating substrate 31. The insulating substrate 31 has a heat insulating layer 39 formed of glass on the surface of a ceramic plate 38 or the like.

  A resistor and electrodes are stacked on the surface of the insulating substrate 31. Of these resistors, portions where the electrodes are not stacked are heating resistors 91, 92, 93, 94.

  The heating resistors 91, 92, 93, 94 are arranged in the longitudinal direction (main scanning direction) of the insulating substrate 31 with an interval on the surface of the insulating substrate 31, and form a belt-like heating region 32 extending substantially linearly. doing. Each of the heating resistors 91, 92, 93, 94 extends in the sub-scanning direction perpendicular to the main scanning direction. A protrusion may be provided on the heat retaining layer 39, and the heating resistors 91, 92, 93, 94 may be formed on the protrusion.

  These heating resistors 91, 92, 93, 94 are arranged in the arrangement direction (main scanning direction) in the first heating resistor 91, the second heating resistor 92, the third heating resistor 93, and the fourth heating resistor 94. Are repeatedly arranged in order. The second heating resistor 92 and the third heating resistor 93 are connected by a first folded electrode 81. The first heating resistor 91 and the fourth heating resistor 94 are connected by a second folded electrode 82. The second folded electrode 82 extends along the first folded electrode 81.

  Two intermediate electrodes 12 and 14 are provided in the middle of the first heating resistor 91 and the fourth heating resistor 94 in the sub-scanning direction. The intermediate electrodes 12 and 14 are made of, for example, titanium (Ti) having high heat resistance. As a result, the first heat generating resistor 91 and the fourth heat generating resistor 94 are divided into three parts of an upstream part 11, an intermediate part 13, and a downstream part 15 in the sub-scanning direction.

  In the heating resistors 91, 92, 93, 94, electrodes 71, 72, 73, 74 extend from the opposite ends of the folded electrodes 81, 82, respectively. The first electrode 71 connected to the first heating resistor 91 and the third electrode 73 connected to the third heating resistor 93 extend to the bonding pad 33, respectively. The second electrode 72 connected to the second heating resistor 92 and the fourth electrode 74 connected to the fourth heating resistor 94 are connected to the reference potential electrode 75. A predetermined reference potential is applied to the reference potential electrode 75.

  A part of the surface of the heating plate 30 is covered with a protective layer 36. The region where the bonding pad 33 of the heating plate 30 is formed is not covered with the protective layer 36 and is exposed.

  The circuit board 41 is a printed board using, for example, glass epoxy resin as an insulator base material. A wiring pattern is formed on the surface of the circuit board 41, and the wiring pattern is covered with an insulating film except for a connection portion with the outside.

  A drive element 42 is mounted on the circuit board 41. The drive element 42 is a semiconductor integrated circuit (IC).

  The heating plate 30 and the circuit board 41 are placed on the surface of the heat dissipation board 20. The heat generating plate 30 and the circuit board 41 are bonded to the surface of the heat dissipation board 20 with, for example, a double-sided tape. The heating element plate 30 and the circuit board 41 are arranged so that the long side of the heating element plate 30 near the bonding pad 33 and the long side of the circuit board 41 on the side where the driving element 42 is arranged are closely opposed to each other. Has been.

  A bonding wire 51 formed of a metal such as gold, for example, is bridged between the driving element 42 mounted on the circuit board 41 and the bonding pad 33 of the heating plate 30 and is electrically connected.

  The bonding wire 51 is sealed with a sealing resin 52. The sealing resin 52 covers the region exposed without being covered with the protective layer 36 of the heating plate 30, the bonding wire 51, and the driving element 42. The sealing resin 52 is a thermosetting epoxy resin. This sealing is performed by applying an epoxy resin and curing it by heating at about 100 ° C. for several hours.

  FIG. 4 is a cross-sectional view of a thermal printer using the thermal print head of the present embodiment.

  The thermal printer using the thermal print head 10 according to the present embodiment has a conveying means for a printing medium 64 such as paper. The conveying means for the printing medium 64 is, for example, a platen roller 60. The platen roller 60 is an elastic cylinder having a shaft 61 as a straight line parallel to a linear heat generating region in which the heat generating resistors 91, 92, 93, 94 are arranged.

  The thermal printer also includes a thermal ribbon 63 that is a thermal recording medium. The thermal ribbon 63 is wound around a shaft 65 parallel to the shaft 61 of the platen roller 60 in a roll shape. The heat-sensitive ribbon 63 wound in a roll shape is wound around an axis 66 parallel to the axis 65. The winding-side shaft 66 is driven by a motor or the like.

  The thermal ribbon 63 is conveyed so as to pass between the side surface of the platen roller 60 and the thermal print head. The print medium 64 is conveyed so as to pass between the thermal ribbon 63 and the platen roller 60.

  The thermal ribbon 63 has a plurality of types of color areas and an overcoat area in the winding direction. Each color area of the thermal ribbon 63 is colored when a predetermined temperature or higher is reached, and the color is transferred to the printing medium 64 in contact therewith. The overcoat region of the thermal ribbon 63 is partially melted when heated, and an overcoat is formed on the surface of the printing medium 64 that is in contact therewith.

  The drive element 42 has the second heating resistor 92 and the third heating resistor at predetermined positions when printing, that is, when the respective color regions of the thermal ribbon 63 are positioned on the heating resistors 91, 92, 93, 94. A current is passed through the body 93 and the first heating resistor 91 and the fourth heating resistor 94 to generate heat. As a result, one line of a predetermined image is drawn on the print medium 64. One dot is printed by the four heating resistors 91, 92, 93, 94. For the printing of one dot, the case where only the second heating resistor 92 and the third heating resistor 93 are heated, the second heating resistor 92 and the third heating resistor 93, and the first heating resistor 91 and The fourth heating resistor 94 may generate heat.

  Further, the drive element 42 has all of the heating resistors 91, 92, 93, when overcoating, that is, when the overcoat region of the thermal ribbon is located on the heating resistors 91, 92, 93, 94. A current is passed through 94 to generate heat. As a result, an overcoat is formed over the entire printing area of the printing medium 64.

  In the present embodiment, for example, when printing at 300 dpi, the four heating resistors 91, 92, 93, 94 are taken as one group, and the distance (pitch) between the centers of adjacent groups is 84.5 μm. . At this time, the width of the heating resistors 91, 92, 93, 94 in the main scanning direction is, for example, 8 μm. In this case, when two heating resistors are considered as a set like a conventional folded thermal print head, the heating resistors are arranged at an equivalent of 600 dpi. The width may be changed between the one-dot inner heating resistors 92 and 93 and the outer heating resistors 91 and 94.

  In the folded electrode type thermal print head, it is not necessary to provide a common electrode at a position away from the heating resistor downstream in the sub-scanning direction. Therefore, the size can be reduced as compared with the common electrode type thermal print head. In particular, the length on the downstream side in the sub-scanning direction with respect to the heating resistors 91, 92, 93, and 94, which tends to hinder the conveyance of the printing medium, can be shortened. On the other hand, in the folded electrode type thermal print head, since the heating resistor that draws the same pixel is divided into two, the surface temperature of the protective layer 36 increases due to the heat generation of the heating resistor, that is, a thermal ribbon or the like. The amount of heat transferred to the thermal recording medium tends to be small.

  However, in the present embodiment, the four heating resistors 91, 92, 93, 94 form a set. When printing is performed using the two heating resistors 92, 93 at the center of the four heating resistors 91, 92, 93, 94, the heating resistors 92, 93 for printing are printed at the center position of each pixel. Are placed close together. For this reason, the temperature peak by the heating resistors 92 and 93 that draw the same pixel can be increased.

  When printing using all four heating resistors 91, 92, 93, and 94, the width of the temperature distribution by the heating resistors 91, 92, 93, and 94 that draw the same pixel is widened in the main scanning direction. It can be flattened as a whole. Further, in the present embodiment, the first heat generating resistor 91 and the fourth heat generating resistor 94 are divided into three parts of an upstream part 11, an intermediate part 13, and a downstream part 15 in the sub scanning direction. The length of the upstream portion 11 and the downstream portion 15 in the sub-scanning direction is longer than that of the intermediate portion 13. That is, the amount of heat generated in the upstream portion 11 and the downstream portion 15 is larger than that in the intermediate portion 13.

  For this reason, in the first heating resistor 91 and the fourth heating resistor 94, the temperature peaks shift from the center in the sub-scanning direction to the upstream side and the downstream side. Therefore, the temperature distribution within one dot when printing is performed using all of the four heating resistors 91, 92, 93, 94 is also flattened in the sub-scanning direction.

  As described above, according to the present embodiment, the temperature distribution within one dot is increased by using the two heating resistors 92 and 93, or the four heating resistors 91, 92, 93, and 94 are By using it, it can be flattened. As a result, the dot size can be finely controlled, printing with more detailed gradation is possible, and the print quality can be improved.

  When the overcoat is formed on the printing medium 64, the overcoat becomes uneven if the temperature distribution in the main scanning direction is not uniform. Therefore, in the present embodiment, the four heating resistors 91, 92, 93, 94 are heated during overcoating. For this reason, the temperature distribution in the main scanning direction can be made uniform, and the possibility of unevenness in the overcoat is reduced. Further, the possibility of sticking of the thermal ribbon 63 that is a medium in contact with the thermal print head 10 is suppressed, and the running resistance is reduced.

As described above, in the present embodiment, it is possible to improve the uniformity of the overcoat while improving the gradation expression with the folded thermal print head.
[Second Embodiment]

  FIG. 5 is a partially cut-out top view of the thermal print head according to the second embodiment of the present invention.

  In the present embodiment, an after heat portion 88 is formed in the middle of the second folded electrode 82. In the afterheat part 88, the resistor is exposed without being covered with the electrode. The after heat portion 88 extends in the main scanning direction, and two intermediate electrodes 84 and 86 are provided in the middle thereof. The intermediate electrodes 84 and 86 are made of Ti having high heat resistance, for example. Thereby, the after heat part 88 is divided | segmented into the three parts 83, 85, 87 in the main scanning direction.

  Thus, by providing the after-heat part 88 in the middle of the second folded electrode, the temperature of the thermal ribbon 63 heated by the heating resistors 91, 92, 93, 94 is suppressed from rapidly decreasing. As a result, the possibility of sticking the thermal ribbon 63, which is a medium that contacts the thermal print head 10, is suppressed, and the running resistance is reduced.

Furthermore, in the present embodiment, since the after heat part 88 is divided into a plurality of regions in the main scanning direction, the temperature distribution of the after heat part 88 is flattened in the main scanning direction, whereby the thermal ribbon 63 is attached. The possibility of attachment can be further suppressed, and the running resistance can be further reduced. Further, since the temperature drop of the overcoat becomes uniform in the main scanning direction, the finished quality of the printing medium 64 is 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, 11 ... Upstream part, 12 ... Intermediate electrode, 13 ... Intermediate part, 14 ... Intermediate electrode, 15 ... Downstream part, 20 ... Heat dissipation board, 30 ... Heat generating board, 31 ... Insulating board, 32 ... Heat generation Region 33, bonding pad 36, protective layer 38, ceramic plate, 39 thermal insulation layer 41 circuit substrate 42 drive element 51 bonding wire 52 sealing resin 60 platen roller 63 Thermal ribbon, 64 ... printed medium, 71, 72, 73, 74 ... electrode, 75 ... reference potential electrode, 81,82 ... folded electrode, 84,86 ... intermediate electrode, 88 ... after-heat part, 91,92,93 94 Heating resistor

Claims (7)

In a thermal print head used for a thermal printer that prints on a printing medium and overcoats a printing screen,
An insulating substrate;
A plurality of heating resistors arranged at intervals on the surface of the insulating substrate;
The plurality of heating resistors are the second heating resistors when the first heating resistor, the second heating resistor, the third heating resistor, and the fourth heating resistor are repeatedly arranged in the arrangement direction. And a first folded electrode connecting the third heating resistor,
A first electrode connected to one of the second heating resistor and the third heating resistor on the opposite side of the first folded electrode;
A second folded electrode connecting the first heating resistor and the fourth heating resistor;
A second electrode connected to one of the first heating resistor and the fourth heating resistor on the opposite side of the second folded electrode;
A driving element connected to the first electrode and the second electrode to cause the second heating resistor and the third heating resistor to generate heat during printing, and to generate heat to all of the heating resistors during overcoating;
Comprising
The first heating resistor and the fourth heating resistor are divided in the transport direction of the print medium,
A thermal print head characterized by that.   The first heat generating resistor and the fourth heat generating resistor are arranged in an upstream portion in the transport direction of the printing medium, an intermediate portion downstream from the upstream portion, and a downstream portion downstream from the intermediate portion. The thermal print head according to claim 1, wherein the thermal print head is divided, and the upstream portion and the downstream portion are longer than the intermediate portion.   The fifth heating resistor is provided at a position downstream from the second heating resistor and the third heating resistor in the middle of the second folded electrode in the transport direction. The thermal print head according to claim 2.   The thermal print head according to claim 3, wherein the fifth heating resistor is divided into a plurality of portions in the arrangement direction of the heating resistors.   5. The thermal print head according to claim 1, wherein the second folded electrode extends along the first folded electrode. 6.   6. The thermal print head according to claim 1, wherein the plurality of heating resistors are arranged at equal intervals. In a thermal printer that prints on a printing medium and overcoats the printing screen,
An insulating substrate;
A plurality of heating resistors arranged at intervals on the surface of the insulating substrate;
The second heating resistor when the plurality of heating resistors are classified as the first heating resistor, the second heating resistor, the third heating resistor, and the fourth heating resistor are repeatedly arranged in the arrangement direction. A first folded electrode connecting the body and the third heating resistor;
A first electrode connected to one of the second heating resistor and the third heating resistor on the opposite side of the first folded electrode;
A second folded electrode extending along the first folded electrode and connecting the first heating resistor and the fourth heating resistor;
A second electrode connected to one of the first heating resistor and the fourth heating resistor on the opposite side of the second folded electrode;
A driving element connected to the first electrode and the second electrode to cause the heating resistor to generate heat;
Conveying means for conveying the printing medium;
Comprising
The first heating resistor and the fourth heating resistor are divided in the transport direction of the print medium,
A thermal printer characterized by that.

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