JPH04250073A - Thermal head - Google Patents

Abstract

PURPOSE:To save an electric power and effectively prevent sticking by partially forming a heat accumulation layer in a thermal head. CONSTITUTION:Grooves 32, 34 having a predetermined volume are formed on a substrate 16 under a resistor layer 128. Glaze layers 126, 127 are formed in the grooves 32, 34. In this manner, a partially-glazed type head is produced for saving an electric power, and the projected amount of a printing part is reduced for preventing sticking. In addition to the glaze layer 127 formed in said groove 34, a thin film 127a made of the same material as the glaze layer is also formed on the substrate 16, whereby simultaneously a fine pattern is allowed to be formed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the structure of a thermal head used in a print head of various devices such as a printer.

0002

[Prior Art] Conventionally, page printers, word processors,
Thermal heads are used as print heads in various devices such as facsimile machines. In Figure 3,
The state of the thin-film thermal head after wire bonding is shown, and the thermal head 10 has a one-dot row of printed portions 14 formed on the side opposite to the connecting portions 12 of the flexible substrate.

FIG. 4(a) shows a sectional view taken along the line AA of the thin film thermal head 10 shown in FIG. A certain glaze layer 18 is partially formed. A lead 20a of a predetermined width is placed on this glaze layer 18.
, 20b (common lead and individual leads) are printed for each dot (in the depth direction of the figure), and a resistor layer 22 is formed between the leads 20a and 20b. A protective film 24 is attached to the surfaces of the leads 20a and 20b.

FIG. 4(b) shows a cross section of a thick film type thermal head, in which an arcuate resistor layer 28 is formed on the glaze layer 26 and the leads 20a, 20b. A protective film 30 is deposited on the surfaces of the resistor layer 28 and the leads 20a, 20b.

In the conventional thin film type and thick film type thermal heads as described above, glaze layers 18 and 26, which are heat storage layers, are also formed on the entire surface between the substrate 16 and the resistor layers 22 and 28. However, this would increase power consumption, so the glaze layers 18 and 26 are partially formed near the bottom of the resistor layers 22 and 28 as shown in FIG. Reductions are being made. Figure 5 shows the change in power consumption to obtain a blackness with an optical density (OD) of 1.2, with the horizontal axis representing the printing cycle and the vertical axis representing the amount of power. Glaze type curve 101 and partial glaze type curve 1
02, it is clear that the partial glaze type achieves a blackness of OD=1.2 with significantly lower power.

[0006]

[Problems to be Solved by the Invention] However, in the conventional partial glaze type thermal head described above, the platen pressure is most concentrated in the area showing the peak temperature within the dot, which causes the fixation of the thermal ink, so-called sticking. There was a problem in that it was more likely to occur. That is, as shown in FIG. 4, in the partial glaze type, the resistor layer 22
, 28 portions (printed portion 14), and the temperature is highest at this apex portion. Therefore, the pressure applied from the platen through the printing paper is the highest at the vertex, causing the thermal ink to stick.

The present invention has been made in view of the above problems, and its object is to provide a thermal head that can partially form a heat storage layer to save power and effectively prevent sticking. It is about providing.

[0008]

Means for Solving the Problems In order to achieve the above object, the present invention provides a thermal head in which a partial glaze layer is formed between a substrate and a resistor layer. A groove with a predetermined volume is formed in the groove, and a glaze layer is formed in the groove.

[0009] Further, it is possible to form a glaze layer of a predetermined volume in a groove formed in the substrate below the antibody layer, and also to form a thin film of the glaze layer material on the substrate.

0010

[Operation] According to the above structure, since the glaze layer is embedded in the insulating substrate, the protrusion of the printed portion is reduced, and sticking is less likely to occur. Furthermore, if a thin film of the glaze layer material is also formed on the substrate, the surface of the insulating substrate made of ceramic material becomes smooth, making it possible to form a fine circuit pattern.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows cross sections of two types of thermal heads according to embodiments of the present invention, and these thermal heads are of a thick film type. In Figure (a), a groove 32 is formed in a substrate 16 made of alumina ceramic, which is an insulating material, using a diamond disk or the like, and this groove 32 has a size that allows the glaze layer 126 as a heat storage layer to secure the same heat capacity as the conventional one. It is designed to have a volume that can accommodate only For example, the size of this groove 32 can be 300μ in width and 50μ in height, and when the glaze layer 126 is formed in this groove 32, the upper part becomes slightly raised as shown in the figure. Of course, the glaze layer 126 is of a partial glaze type, which is different from the conventional full-surface glaze type, and can obtain a predetermined heat storage effect.

Then, leads (common lead and individual leads) 120a and 120b are formed by printing and etching so as to face each other in the center of this glaze layer 126, and these leads 120a and 120b are formed by one dot in the depth direction of the figure. Arranged in multiple columns for each. After the above-mentioned leads 120 are formed, a resistor layer 128 having a width of, for example, 200μ is formed on the leads 120 and the above-mentioned glaze layer 126, and then a protective film 130 is attached to provide thermal protection. Head 10 is manufactured.
According to the above configuration, the glaze layer that was conventionally formed on the top of the substrate 16 is embedded inside the substrate 16, and the amount of protrusion of the apex of the printed portion (14) is reduced accordingly. It is possible to reduce the platen pressure caused by

In the case of FIG. 1(b), a glaze layer 127 capable of obtaining a predetermined heat capacity is formed in the groove 34 cut in the same manner as above in the alumina ceramic substrate 16,
Furthermore, a thin glaze layer 127a is formed over the entire area including this groove 34.
form. Generally, the ceramic used as the substrate 16 has a rough surface, so if a fine pattern is drawn, problems such as etching defects and short circuits occur. Therefore, in the embodiment, a thin glaze layer 127a is simultaneously formed on the substrate 16 to smooth the surface of the substrate so that a fine pattern can be formed. Note that the lead 120 in the post-process,
The formation of the resistor layer 128 and the protective film 130 is the same as in the case of FIG.

FIG. 2 shows the change in power consumption in the above embodiment in a graph in which the horizontal axis represents the printing cycle and the vertical axis represents the amount of power.
This is the change in power consumption to obtain a blackness of 1.2, and was measured with the glaze layer 126 having the size shown in FIG. 1 above. In the case of the example, the power consumption is shown by a curve 103, and as is clear from the figure, a blackness of OD = 1.2 can be obtained with lower power than the curve 101 for the entire glaze, and it is possible to obtain a blackness of OD = 1.2 for the partial glaze. When compared with curve 102, the power consumption is slightly higher. This is because the present invention forms the glaze layers 126, 127 within the grooves 32, 34 to reduce the amount of protrusion of the apex of the printed portion, making the contact efficiency with the paper smaller than before.

In the above embodiment, an example was shown in which the present invention was applied to a thick film type thermal head, but grooves can be similarly formed and a glaze layer can be formed in a thin film type thermal head.

Furthermore, in the embodiment, the entire amount of glaze (heat storage layer) for obtaining the necessary heat capacity was formed within the grooves 32 and 34, but in consideration of the final swelling of the printed area, The groove may have a volume that accommodates a predetermined amount of glaze, and the remaining glaze layer may be raised thereon.

[0017]

As described above, according to the first aspect of the invention, a groove of a predetermined volume is formed in the substrate below the resistor layer, and a glaze layer is partially formed in this groove. As a result, the protruding state of the apex of the dot printing area is alleviated,
In addition to being able to save power, it is possible to effectively prevent a phenomenon in which thermal ink sticks, that is, so-called sticking. In addition to forming a glaze layer within the groove, a thin film of glaze layer material was also formed on the substrate.
In addition to obtaining the above effects, the surface of a substrate made of ceramic or the like can be made smooth, and fine patterns can be formed without causing etching defects or short circuits.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the structure of a thermal head according to an embodiment of the present invention; FIG. 1(a) is a diagram in which a glaze layer is formed only in the groove portion, and FIG. It is a figure when a glaze layer is formed in.

FIG. 2 is a graph diagram showing changes in power consumption in the thermal head of the example.

FIG. 3 is an overall view of a conventional thermal head after wire bonding.

[Fig. 4] A- in Fig. 3 showing the structure of a conventional thermal head.
It is an A sectional view.

FIG. 5 is a graph diagram showing changes in power consumption in a conventional thermal head.

[Explanation of symbols]

10 Thermal head 16 Substrate 18, 26, 126, 127 Glaze layer 20a, 2
0b Leads 22, 28, 128 Resistor layer

Claims (2)

[Claims] 1. A thermal head in which a partial glaze layer is formed between a substrate and a resistor layer, wherein a groove of a predetermined volume is formed in the substrate below the resistor layer, and a glaze layer is formed in the groove. A thermal head characterized by a formed 2. A thermal head in which a partial glaze layer is formed between a substrate and a resistor layer, wherein a groove of a predetermined volume is formed in the substrate below the resistor layer, and the glaze layer is formed in the groove. A thermal head characterized in that a thin film of the above-mentioned glaze layer material is also formed on a substrate.