JPH0586755B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the structure of a thermal head, and particularly provides a highly reliable thermal head with excellent environmental resistance, and also improves the printing power efficiency of the thermal head. Related to reducing power consumption.

[Conventional technology]

FIG. 2A is a schematic plan view of a conventional thermal head, as shown in Japanese Patent Application No. 59-187623, and FIG. 2B is a P of FIG.
A cross-sectional view of the −P′ section is shown. In the figure, 21 is, for example, an alumina substrate, 22 is a glaze partially formed on the substrate, 23 is a conductor that is generally connected to a power source as a common electrode, and 24
is a conductor branched into a rectangular shape from the common electrode 23 and connected to the heating resistor 25, and 26 is an individual conductor formed extending from the other end of the heating resistor to the connection terminal to the IC. be. The area shown in the figure is covered by a protective layer (wear-resistant layer) of the heating resistor. The substrate material is generally alumina, enamel, silicon carbide, etc., and the conductor material is generally a base metal such as aluminum, copper, etc., and is also used in conjunction with a noble metal such as gold, platinum, etc.

In this conventional partially glazed substrate, a layer 25 for the heating resistor is formed in a direction perpendicular to the illustrated partial glaze 22, and is further connected to the rectangular conductor 24 and the individual conductors 26 to form the heating resistor 25.
Configure. The partial glaze is generally provided symmetrically with respect to the resistor in the lower layer of the heat generating resistor 25, and is used for the purpose of smoothing the alumina surface and accumulating heat. In the thermal head, the amount of heat generated by the heat generated by each heating resistor is conducted to and sinks into the alumina portions at both ends of the resistor. Therefore, the thermal head has excellent thermal response characteristics.

Further, the heat-sensitive recording paper on which printing is performed by the resistor 25 develops color and generates molten chemical substances. This chemical substance is peeled off from the recording paper by friction with the protective layer or wear-resistant layer intended to protect the resistor, and is recorded in the shape shown by the broken line in FIG. 2B in the feeding direction of the recording paper. It will be accumulated as waste. In addition, there are alumina regions with rough surfaces on both sides of the glaze in the direction of travel of the print recording paper, and the resistor protective layer formed on these regions has countless defects.

[Problem that the invention seeks to solve]

As mentioned above, the conventional thermal head described above has countless defects in the resistor protective layer, so halogen elements contained in the printed recording paper and recording waste can easily pass through the defects and penetrate into the lower layer. It diffuses and reaches the conductor, corroding the underlying conductor. Therefore, the reliability of manufactured thermal heads is inevitably low.

In addition, since strip-shaped conductors and individual conductors are separated from each other on alumina and formed over a long distance in narrow shapes of 200 microns or less, extremely small conductors with a diameter of 100 microns or less can be formed. Even if corrosion occurs, the thermal head will fail catastrophically. That is, since this corrosion progresses in the form of a thread along a narrow conductor, the conductor that begins to corrode will break within a short time.

Furthermore, since the amount of heat generated by the heat generated by each heating resistor is conducted to and sinks into the alumina portions at both ends of the resistor, the printing power efficiency of the thermal head is also reduced by applying glaze to the entire surface of the board. lower than that of the thermal head.

Accordingly, the present invention increases the reliability and printing power efficiency of a partially glazed thermal head without sacrificing the thermal response characteristics that characterize the thermal head.

[Means for solving problems]

The thermal head according to the present invention has a second glaze in which a 0.1 to 3 mm alumina part is exposed before and after the glaze formed on the heating resistor part in the running direction of the print recording paper, thereby preventing defects. The goal is to minimize the area of exposed alumina-rich regions.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a plan view schematically showing an embodiment of the present invention, and FIG. 1B is a schematic sectional view taken along the line Q--Q' in FIG. In the figure, reference numeral 11 is an alumina substrate, and a heating resistor array 15 is disposed on the substrate.
The first glaze 12 is applied to the width W in a symmetrical manner with . The width of W is generally 0.3~
It is 3 mm, preferably about 1 mm. Further, a second glaze 14 is provided with a width of W' on the side of the common electrode from the first glaze. The width of W′ is
It is 0.5 mm or more, preferably 1 mm or more. Similarly, a second glaze 18 is provided with a width of W'' from the first glaze to the individual conductor side. The width of W'' is determined as appropriate depending on the dimensions of the substrate and the like. In the gaps between the first glaze 12 and the second glazes 14 and 18, anglaze portions (alumina portions) having widths of "l" and "l'" are formed, respectively. A heating resistor film 15 and a conductor film are accumulated in a desired shape on this partially glazed substrate 11, and the conductor film includes a common electrode 13 and a conductor branched into strips from the common electrode. 14, or an individual conductor 16 formed at the other end of the heating resistor and extending to a connection terminal to the IC. Further, in the upper or lower layer of the common electrode 13, a conductor such as silver, copper, nickel, gold, etc., which is formed into a desired shape by a printing method, plating method, spinner method, etc., may be used as a low-area resistance conductor, if necessary. 1 to 80 materials
It is formed to a thickness of microns, preferably from 5 to 30 microns. The common electrode conductor 13 covers a wide area of the alumina portion on the strip-shaped conductor side.

Now, when power is applied to the heating resistor of the thermal head to cause it to generate heat, and the power required to color the thermal recording paper to a constant density using the generated energy is determined as shown in FIG. 1C. In other words, the printing power efficiency of the conventional thermal head shown in Figure 2 has been reduced to 100%.
Assuming that, the printing efficiency increases as the widths l and l' of the alumina regions provided at both ends of the first glaze become narrower. For example, when l = l' = 0.4 mm, the printing power efficiency is 117 %. As is clear from this figure, in order to increase the printing power efficiency of the thermal head and reduce the power consumption of the thermal head, it is necessary to narrow the width of the alumina portion. Practically speaking, the appropriate width of l and l' is 0.1 to 1 mm.

〔Effect of the invention〕

In this way, the thermal head of the present invention has the second glaze applied on both sides of the first glaze.
The alumina area, which is the gap between the glaze and the second glaze, has a width of about 0.1 to 1.0 mm, and if desired, the alumina area on the rectangular conductor side is covered with a common electrode conductor. It is something to do. Therefore, the thermal head of the present invention has a small area of alumina region containing many defects. For these reasons, the number of defects existing in the resistor protective film is reduced, the frequency of occurrence of conductor corrosion phenomena is reduced, and the manufactured thermal head is highly reliable with excellent environmental resistance characteristics. Become something. Furthermore, since the alumina region on the strip-shaped conductor side is covered with a common electrode conductor having a wide area, even if a defect exists in the resistor protective film and the conductor is corroded through this defect, Since this corroded portion functions only as a minute pinhole in a wide conductor area, the manufactured thermal head will not fail catastrophically.

In addition, in the thermal head of the present invention, since alumina regions exist on both sides of the first glaze that includes the heating resistor, the thermal head using a partially glazed substrate has excellent thermal response characteristics. The width of the alumina region is 0.1 to 1.0.
Because the thermal head is narrow (mm), the printing power efficiency of the thermal head is high.

Since the thermal head of the present invention exhibits the above-mentioned effects, the thermal head of the present invention has various uses, shapes,
Resolution of heating resistor, number of image signal terminals to be input, number of heating resistors that can be driven by a single IC, IC
mounting and connection methods, materials and manufacturing methods used, film thickness and
Manufacturing conditions etc. are not particularly limited. Furthermore, as disclosed in Japanese Patent Application No. 60-72143, it is of course possible to cover the common electrode conductor portion and the individual electrode conductor portions on alumina with an insulating resin.

In addition, in the embodiment of the present invention, the lengths of the alumina regions existing on both sides of the first glaze were set to be the same length, but the lengths l and l' may be determined as appropriate without departing from the scope of the present invention. It can be defined as

[Brief explanation of the drawing]

FIG. 1A is a schematic plan view of the vicinity of a heating resistor according to an embodiment of the thermal head of the present invention, and FIG. 1B is a schematic diagram showing a cross-sectional structure taken along the line Q-Q' in FIG. FIG. 1C is a graph showing the printing power efficiency of the thermal head of the present invention as a function of the length of the alumina region. FIG. 2A is a schematic diagram of a conventional thermal head, and FIG. 2B is a schematic diagram of a conventional thermal head.
FIG. 3 is a schematic diagram showing the cross-sectional structure of portion P′. 11...Substrate, 12...First glaze, 13
... common electrode, 14, 18 ... second glaze,
15...Heating resistor, 16...Individual conductor, 17
...Rectangular conductor.

Claims (1)

[Claims] 1 A first plate having a predetermined width formed on an alumina substrate so as to extend in a direction perpendicular to the running direction of the recording paper.
a heating resistor formed on the first glaze and reaching the alumina substrate; and a heating resistor connected to the heating resistor and extending along the running direction of the recording paper. In the thermal head having a group of conductors, second glazes are formed on both sides of the first glaze in the running direction of the recording paper, and the gap width between the first glaze and the second glaze is set to 0.1. ~1.0
mm, and the conductor group is formed on the gap without a glaze.