JPH0674338U - Thermal head - Google Patents

Abstract

(57) [Abstract] [Purpose] In a thermal head in which a plurality of head substrates are in contact with each other, the heat generation dots in the vicinity of the joint surface do not have a difference in heat generation temperature between left and right within one dot, and print quality is improved. Improve. [Structure] When the head substrates 2 are joined by an adhesive or the like, the heating dots 4 are formed on the head substrate 2 so that one dot of the heating dots 4 is divided into two.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a thermal head for a thermal printer or a thermal transfer printer used as a printer for a word processor, a facsimile receiver, or the like, and more particularly to an improvement of a large thermal head having a large recording area. .

[0002]

[Prior art]

 A thermal head installed in a thermal printer such as a conventional thermal printer or a thermal transfer printer has a plurality of heating resistors linearly arranged on a head substrate, and the heating resistors are printed according to print information. Is selectively energized and heated so that color recording is performed on the thermal recording paper, or the ink of the ink ribbon is melted and transferred and recorded on plain paper.

A general thermal head used for heat-sensitive recording paper, as shown in FIG. 5, a head substrate 2 made of alumina or the like is mounted on a heat dissipation plate 1 made of a material having good thermal conductivity such as aluminum. On the head substrate 2, a glaze layer 3 made of glass, which functions as a heat storage layer, is partially formed. This glaze layer 3 is a region where the heating resistor is to be formed. The cross section of the upper surface is formed in an arc shape. A heating resistor 4 made of Ta2N or the like is deposited on the glaze layer 3 by vapor deposition, sputtering, etc. By etching the heating resistor 4, a plurality of heating dots 4A are linearly formed. It is formed so that it may be arranged.

Conventionally, as shown in FIG. 6, for example, the heating dot has a slit 8 formed in the central portion of the heating resistor 4 by etching or the like by photolithography, and the heating dot is further divided into two elongated shapes. There were many things that formed the dots 4A and 4B. The heat-generating dots without the slits 8 have a problem that the heat generation distribution within the dots is concentrated in the central portion of the dots, making it difficult to clearly print a rectangular dot shape. As a countermeasure against this, by providing slits 8 as shown in FIG. 6 and dividing the heating dot into two more elongated shapes, the central heating portion can be dispersed in two positions within the heating resistor 4, and a rectangular dot shape can be obtained. There is an effect that can be printed clearly.

Electrodes 5 for supplying power to the heating dots 4A and 4B are laminated on the heating dots 4A and 4B. The electrode 5 is made of, for example, Ae, Cu, Au or the like, and is formed into a pattern of a desired shape by vapor deposition or sputtering. One of the electrodes 5 is a common electrode 5A on either side of the heating dots 4A, 4B and the other is Are led out as a plurality of individual electrodes 5B, 5B ... Which are arranged with a gap 7 therebetween.

The heating dots 4A and 4B are heated by applying a voltage between the pair of electrodes 5A and 5B. A protective layer 6 for protecting the heating resistor 4 and the electrode 5 is formed on the heating resistor 4 and the electrode 5. The protective layer 6 is an oxidation resistant layer 6A that protects the heating resistor 4 from deterioration caused by oxidation, and is laminated on the oxidation resistant layer 6A to protect the heating resistor 4 and the electrode 5 from abrasion caused by contact with printing paper or the like. And the abrasion resistant layer 6B.

In recent thermal printers using the thermal head having the above-mentioned configuration, there is a strong demand for high printing quality. Along with this, the thermal head heating resistors 4 having a density of 300 dots per inch or more (300 DPI) are becoming mainstream. Therefore, in the thermal head of 300 DPI, the number of dots of the heating resistor 4 when the printing width is set to A4 size is 2,560 dots.

It is very difficult and impossible to uniformly form such a huge number of heating resistors 4 under the same conditions. In a thermal head in which a long head substrate 2 is integrally formed, if only one of the enormous number of heat generating resistors 4 is defective, the other heat generating dots are good products, but the head substrate 2 The entire thermal head including will be defective. Therefore, there has been a problem that the yield of the thermal head becomes very poor.

As a countermeasure against this, in such a long thermal head, as shown in FIG. 6, a gap between the heating resistors 44 is sandwiched between the individual electrodes 5B and 5B. 7 was cut from the central portion, and the above-mentioned end faces of the head substrate 2 having the cut portion as the end face on the short side were brought into contact with each other, and the joining face 9 was joined by an adhesive or the like. By bonding the head substrates 2 as shown in FIG. 6, the yield of a long thermal head could be improved.

[0010]

[Problems to be solved by the device]

 However, a general adhesive used for the joint surface 9 has poor thermal conductivity, and the joint surface 9 in which a plurality of head substrates 2 are brought into contact with each other and joined with an adhesive or the like serves as a heat insulating layer. Therefore, when the head substrate 2 which is cut and divided so as to divide the gap 7 into equal parts is abutted and joined from the central portion of the gap 7 as in the conventional case described above, in the heating dots 4A and 4B near the joining surface 9, the joining surface is formed. The heat-generating dots 4A closer to 9 store more heat than the heat-generating dots 4B far from the joint surface 9, and the heat-generating dots 4A and 4B forming one dot have a difference in heat-generating temperature, which deteriorates the print quality. There's a problem.

For example, referring to FIG. 7, when the heating resistor 4 near the bonding surface 9 of the head substrate generates heat for printing, the heating dot 4 A near the bonding surface 9 is farther from the bonding surface 9. The amount of heat stored is larger than that of the heating dot 4B, and the relationship of the temperature of the heating dot within one dot is 4A> 4B. When printing is performed in this state, uneven printing density occurs within one dot, and the printing quality is remarkably high. There was a problem that it deteriorates and it becomes difficult to express gradation.

The present invention solves the above-mentioned problems of the prior art, and even if a heating dot near the bonding surface 9 of the head substrate 2 has no difference in the heat generation temperature on the left and right within one dot, the dot near the bonding surface 9 is not affected. It is an object of the present invention to provide a thermal head in which unevenness in printing density is less likely to occur even when printing is performed.

[0013]

Means for Solving the Problems In order to achieve the above object, the present invention forms heating dots in an array on a plurality of head substrates, and arranges the plurality of head substrates in an arrangement direction of the heating heads. In a thermal head which is abutted and joined and arranged linearly, one heating dot is divided into two at the abutting and joining end of the head substrate.

[0014]

[Action]

 According to the present invention having the above-mentioned configuration, one dot of the heating dot is divided into two equal parts at the abutting joint end of the head substrate. Therefore, when an adhesive or the like is used on the joint surface of the head substrate, the heat insulation effect is obtained. There is no difference in temperature between the left and right halves of the heat-generating dots, and uneven printing density within one dot does not occur, and good quality printing can be performed.

[0015]

【Example】

 Hereinafter, the present invention will be described with reference to the embodiments shown in the drawings. It should be noted that the same or corresponding configurations as those of the above-described conventional one will be described with the same reference numerals in the drawings. 1 to 3 show an embodiment of a thermal head according to the present invention, in which a head substrate 2 is mounted on a heat dissipation plate 1 made of a material having good thermal conductivity such as aluminum. The heating resistors 4 described in the prior art are formed on the head substrate 2 by etching or the like so that the heating dots are linearly arranged.

A common electrode 5 A is laminated on one side of the heating resistor 4, and a plurality of individual electrodes 5 B, 5 B ... Are laminated on the other side of the heating resistor 4 with a gap 7. . A plurality of heating dots 4A, 4B divided by a slit 8 are formed in an array in the central portion of the heating resistor whose upper portion is exposed between the common electrode 5A and the individual electrode 5B. In a general thermal head, a driving semiconductor for controlling energization of the heating resistors 4, 4, ... Is mounted on the head substrate 2 while being connected to the individual electrode 5B. However, illustration is omitted in this embodiment.

In the present invention, as shown in FIG. 3, the cut surface formed on the central portion of the heating resistor 4 of the head substrate 2 and cut along the center line of the slit 8 is located on the short side of the head substrate. As the end faces, the end faces on the short side of the plurality of head substrates 2 are brought into contact with each other and fixed to the joint surface 9 with an adhesive or the like, and mounted on the heat dissipation plate 1 to form one thermal head. There is. The heat sink 1 and the head substrate 2 are fixed by an adhesive or the like.

For the purpose of improving the yield, which is the object of the present invention, the length of the long side of a single head substrate may be shortened and a large number of short head substrates may be bonded onto one heat sink 1. However, if many short head substrates are joined, conversely, the assemblability of the thermal head will deteriorate, and the joint accuracy of the joint surface 9 will also deteriorate, which will affect print quality. The length of the head substrate should be decided. In a thermal head for printing on A4 size recording paper, it is appropriate to divide the head substrate into 3 to 4 equal parts.

Next, the operation of this embodiment having the above-mentioned configuration will be described. The joint surface 9 in which the end surfaces on the short side of the head substrate 2 are contact-joined to each other is an insulating layer because it is an adhesive layer or an air layer. Therefore, since the common electrodes 5A1 and 5A2 and the individual electrodes 5B1 and 5B2 are insulated, by applying the same amount of voltage separately to each other, the heating dots 4A 'and 4B' generate heat at the same temperature as shown in FIG. To do. However, the heating dots 4A 'and 4B' adjacent to the bonding surface 9 have a higher heating temperature than the other heating dots 4A and 4B far from the bonding surface 9.

As described in the above-mentioned conventional technique, the reason is that the joint surface 9 serves as a heat insulating layer and the heat dissipation of the heat generating dots 4 A ′, 4 B ′ is reduced, so that the heat storage amount is higher than that of the other heat generating dots 4 A ′, 4 B ′. Because it becomes louder. However, if it is known in advance that the heat generation temperature of the heat generation dots 4A 'and 4B' is higher than that of the other heat generation dots in the normal thermal head, the energization control connected to each individual electrode (not shown) is controlled. By controlling the movement of the driving semiconductor, the heating temperature can be controlled to be the same as other heating dots. It should be noted that the present invention is not limited to the above-described embodiment, and various modifications can be made if necessary. For example, a normal type thermal head in which the slit 8 is not provided in the central portion of the heating resistor 4 may be used.

[0021]

[Effect of device]

 As described above, according to the thermal head of the present invention, the difference between the left and right heat-generating temperatures within one dot in the heat-generating resistor in the vicinity of the abutting joint surfaces of the end surfaces on the short side of the plurality of head substrates. Is eliminated, the heat generation temperature on the left and right within one dot of heat generation is the same, and there is no difference in the density of left and right printing within one dot of heat generation dots near the head substrate joint surface, and good quality printing is performed. It has an excellent effect of being able to.

[Brief description of drawings]

FIG. 1 is a front view of a thermal head showing an embodiment of the present invention.

FIG. 2 is a side view of a thermal head showing an embodiment of the present invention.

FIG. 3 is a partial detailed view of an embodiment of the present invention.

FIG. 4 is a graph showing a heat generation state of the thermal head of the present invention.

FIG. 5 is a partial detailed view of a conventional thermal head.

FIG. 6 is a vertical sectional view showing a general thermal head.

[Explanation of symbols]

 4 Heating resistor 4A 'Heating dot 4B Heating dot 5 Electrode 5A Common electrode 5B1 Individual electrode 5B2 Individual electrode 8 Slit 9 Bonding surface

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[Procedure amendment]

[Submission date] March 10, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Figure 7

[Correction method] Added

[Correction content]

[Figure 7] A graph showing the heat generation state of a conventional thermal head.
F

Claims (1)

[Scope of utility model registration request] 1. A thermal head in which heating dots are formed in an array on a plurality of head substrates, and the plurality of head substrates are abutted and joined in the direction of arrangement of the heating dots and arranged linearly. A thermal head in which one dot of a heating dot is divided into two at the abutting joint end of the head substrate.