JPH0371024B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a thermal print head and method of manufacturing the same.

In this type of thermal print head, it is advantageous to install the heating element for printing as close as possible to one edge of the board, since characters printed on thermal paper can be read immediately after printing. It is. However, in a configuration in which current-carrying electrodes are installed across the width of the heating element, it is necessary to secure an installation area for the electrodes between one side edge of the heating element and one end edge of the substrate. Therefore, it was considered impossible to bring the heating element close to one edge of the substrate due to this installation area.

To solve this problem, one electrode and the other electrode connected to both ends of the heating element are both extended toward the opposite edge of the substrate, one electrode is connected to the common electrode, and the other electrode is connected to the common electrode. extending to the surface of the insulating layer formed on the surface of the common electrode;
The inventor separately proposed a configuration in which one electrode connected to the common electrode also extends to the surface of the insulating layer. According to such a configuration, there is no need to install an electrode between one side edge of the heating element and the edge of the substrate, so the heating element can be installed sufficiently close to one edge of the substrate. This is extremely convenient.

Incidentally, this type of heating element is required to be installed on the surface of the glaze layer in order to prevent heat from being conducted to the substrate as much as possible. Therefore, in the previously proposed configuration, a glaze layer is formed on the entire surface of the substrate, and a heating element is formed on a portion of the glaze layer, that is, a portion of the surface near one edge of the substrate. Therefore, this glaze layer and the glaze layer for the above-mentioned insulating layer had to be formed in separate steps. Therefore, there is a drawback that not only the production but also the configuration is extremely complicated.

Furthermore, in forming each electrode, in the existing proposal, the common electrode and each electrode that crosses the heating element in the width direction are subjected to separate etching processes, which makes the manufacturing process complicated.

An object of the present invention is to simplify the configuration in order to bring the heating element sufficiently close to the edge of the substrate by not installing an electrode between the heating element and the edge of the substrate. Another object of the present invention is to facilitate the manufacture of the above structure.

Embodiments of the invention will be described with reference to the drawings. 1 is an insulating substrate such as alumina ceramic. In the present invention, a heating element for printing is installed close to one side of the insulation 1A of the substrate 1. 2 is a common electrode installed on the surface of the substrate 1, and one edge 2A and edge 1A are connected to the space 3.
are relative through. 2B is a lead-out portion of the common electrode 2. Reference numeral 4 denotes an insulating layer covering the surface of the common electrode 2, which is composed of, for example, a glaze layer as described later. This insulating layer 4 covers the edge 2 of the common electrode 2.
At every fixed pitch P on the A side, the edge 2A
The common electrode 2 is covered so that it is exposed. Specifically, a branch electrode 2C is formed at each pitch P on the edge 2A of the common electrode 2 (see the figures after FIG. 2), and the insulating layer 4 is formed by leaving this branch electrode 2C. It is made to cover the common electrode 2.

An insulating layer 5 is formed on the surface of the substrate 1 on the side of the edge 1A, also made of a glaze layer or the like. Then, electrodes 6 and 7 are formed so as to extend from this insulating layer 5 to the surface of the insulating layer 4 via the space 3. Electrode 6 serves as an individual electrode and is arranged between electrodes 7. The electrode 7 serves as a common electrode, and overlaps each branch electrode 2C exposed from the insulating layer 5 in the space 3. Reference numeral 8 denotes a heating element for printing, which is formed on the surface of the insulating layer 5 so as to cross each of the electrodes 6 and 7 in its width direction. Reference numeral 9 denotes a drive circuit made of an integrated circuit or the like, which is installed on the surface of the insulating layer 4 to selectively energize the heat generating region 8A of the heat generating element 8 divided by the electrodes 6 and 7 to generate heat. Reference numeral 10 denotes a terminal electrode that externally supplies a drive signal to the drive circuit 9, and 11 a wire such as a gold wire that connects the electrode 6, the terminal electrode 10, and the drive circuit 9. Although not shown, a protective film, a wear-resistant film, etc. are formed on these surfaces as necessary.

In the above configuration, if the lead-out portion 2B is connected to one terminal of the power source for heat generation, one end of all the heat-generating regions 8A is connected to one terminal of the power source via the lead-out portion 2B, the branch electrode 2C, and the electrode 7. It will be connected. Therefore, if the electrode 7 is then selectively made the other terminal of the power source in accordance with the output signal of the drive circuit 9, the heat generating area 8A will selectively generate heat. These operations are not particularly different from those of this type of thermal print head.

However, as can be understood from the above explanation, in this configuration, the glaze layer is not uniformly formed on the surface of the substrate 1 as in the previous proposal, but the glaze layer is formed on the surface of the previously formed common electrode and on the surface of the substrate 1. Insulating layers 4 and 5 are provided on the edge 1A side. Further, no glaze layer is provided between the common electrode 2 and the substrate 1. Therefore, the provision of glaze layers on the front and back surfaces of the common electrode as previously proposed is omitted, which simplifies the configuration for insulating the common electrode. In other words, in the previously proposed configuration, the surface of the substrate 1 has a three-layer structure consisting of the lowermost glaze layer, the common electrode, and the glaze layer on the surface, whereas in this invention, the lowermost glaze layer This means that a two-layer structure can be used without the . This two-layer structure was made possible by providing the insulating layer 5 of only the heating element 8. Then, as described later, both insulating layers 4,
If you execute Grace printing and firing at the same time in step 5,
It can be formed in a single process, which makes manufacturing easier.

Next, the manufacturing method according to the present invention will be explained with reference to FIG.

First, the common electrode 2 and the conductor portion 2B are formed on the surface of the substrate 1 by screen printing as shown in A of FIG. At this time, branch electrodes 2C are also formed at the same time.
However, this branch electrode 2C is formed to have a width sufficiently wider than the electrode 7 as shown in the figure. This is to facilitate alignment of the mask when etching the electrode 7, as will be described later. 2C' is an electrode portion that becomes a branch electrode 2C by etching. The edge 2A of the common electrode 2 is the edge 1A of the substrate 1.
As mentioned above, they are further apart.

In the existing proposals, the common electrode 2 was formed by etching. This is because in order to maintain the accuracy of overlapping with the electrode 7, it was necessary to set the position of the overlapping portion with high accuracy. However, as described above, if the electrode portion 2C' which is wider than the electrode 7 is used, the positioning becomes easy, and therefore high positional accuracy is not required. Therefore, even if the common electrode 2 is formed not by etching but by screen printing with low positional accuracy, no particular trouble will occur.

Next, insulating layers 4 and 5 are formed as shown in FIG. 3B. This is preferably formed by glaze screen printing, and both insulating layers 4 and 5 can be formed simultaneously by one screen printing and firing.

Next, an etching process is performed for the electrodes 6, 7 and the terminal electrode 10. For this purpose, first, as shown in FIG. 3C, an electrode layer 12 is formed on the surface of the substrate 1 by, for example, screen printing. This is then etched according to the required pattern. At this time, since the electrode portion 2C' is wider than the electrode 7, there is a corresponding margin for positioning the mask for forming the electrode 7, so that the mask can be easily positioned. Further, the electrode portions 2C' protrude on both sides of the formation position of the electrode 7. By not applying resist to this protruding portion, the resist is simultaneously removed along with other portions by etching. As a result, the electrode 7 and the branch electrode 2C are formed to overlap each other with their side surfaces aligned.

Thereafter, a heating element 8 is formed on the surface of the insulating layer 5 so as to cross the electrodes 6 and 7, or a driving circuit 9 is installed on the surface of the insulating layer 4. After connection with the wire 11, it is covered with a protective film, a wear-resistant film, etc.

When manufactured using this method, compared to the previously proposed configuration, not only the insulating layer formation process is required only once, but also the electrode formation etching process is required once, so the manufacturing process is extremely simplified. It will become as follows.

As described in detail above, according to the present invention, when a heating element is installed close to one edge of a substrate, the configuration for this purpose can be simplified compared to the previously proposed one, and the manufacturing thereof can be simplified. Also in the process, by reducing both the etching process and the insulating layer forming process, the process can be simplified accordingly.

[Brief explanation of drawings]

Figure 1 is a plan view showing an embodiment of the invention, Figure 2 is a plan view showing an embodiment of the invention.
The figure is a partially enlarged perspective view, and FIG. 3 is a plan view for explaining the manufacturing process of the present invention. 1...Substrate, 1A...Edge, 2...Common electrode,
2A... Edge, 2C... Branch electrode, 4... Second insulating layer, 5... Second insulating layer, 6... Second electrode, 7... First electrode, 8... Heat generation Body, 12...
electrode layer.

Claims (1)

[Claims] 1. A first insulating layer made of glaze is provided on the surface of an insulating substrate along one edge thereof, and a common electrode is provided at a position spaced apart from the first insulating layer, The first layer of the common electrode is disposed on the surface of the common electrode.
A second insulating layer is provided along the edge of the insulating layer side at a predetermined interval so that a branch electrode that is a part of the common electrode is exposed, and further both the first and second insulating layers are A plurality of first and second electrodes are arranged alternately in parallel along one edge of the substrate, and the first electrode is overlapped with the branch electrode and connected to the common electrode, Further, the second electrode can be selectively energized as an individual electrode, and a heating element for printing is provided on the surface of the first insulating layer so as to cross the first and second electrodes. Thermal print. 2. A first step of forming a common electrode on the surface of an insulating substrate by screen printing so that one edge of the substrate is spaced apart from one edge of the substrate; a first insulating layer along the surface of the common electrode, and a second insulating layer on the surface of the common electrode such that a branch electrode wider than the current-carrying electrode is exposed at a predetermined interval on one edge side of the common electrode. a second step of simultaneously forming the layers by printing and baking a glaze; a third step of forming an electrode layer in a region including at least an electrode formation position for energizing the heating element; first and second electrodes spanning the surfaces of the first insulating layer and the second insulating layer are formed so as to be alternately located along one edge of the substrate, and the first electrode overlaps with the first electrode. a fourth step of etching the electrode layer so that the branch electrode has the same width as the first electrode; and a fourth step of etching the electrode layer so that the branch electrode has the same width as the first electrode; A method for manufacturing a thermal print head, comprising a fifth step of forming a heating element for printing.