JPS6112786B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal head in which a heating resistor is protected from static electricity.

As is well known, a thermal head records characters, symbols, figures, etc. by contacting a thermosensitive recording paper that develops color under heat, and is constructed as shown in FIG. That is, in the figure, 10 is an insulating substrate, 11 is a heating resistor, 12 is an individual electrode, and 13 is a common electrode. The individual electrodes 12 and the common electrode 13 are formed on the insulating substrate 10 by means such as printing, vapor deposition, adhesion, etc.
A heating resistor 11 is similarly formed between the common electrode 2 and the common electrode 13 by printing, vapor deposition, or other means. Then, when a voltage is selectively applied between the individual electrodes 12 and the common electrode 13 depending on the characters to be recorded, a current flows through the heating resistor 11, and this current causes the heating resistor 11 to generate heat. Thermal recording paper 1
4.

By the way, the groups A, B, and C, which are made up of the common electrode 13, the heating resistor 11, and the individual electrodes 12, are insulated from each other with a small gap S. When cleaning or the like is performed with such a single thermal head, the electrodes of groups A, B, and C are charged with static electricity due to friction and the like. For example, if the charges are significantly different between groups A and B, a discharge phenomenon occurs between the individual electrodes 12 or the common electrode 13 that constitutes the gap S between groups A and B, and a discharge occurs in the discharge circuit. There is a disadvantage that a large current suddenly flows through the heat generating resistors 11, which may damage the heat generating resistors 11 or change the resistance value of the heat generating resistors 11. Furthermore, even if the charges of groups A, B, and C are approximately the same, if you touch the electrode of group A with your hand, for example, the charge of group A decreases, so a discharge phenomenon occurs in the same way as above, and the heating resistor 11 There are drawbacks such as damage to the

This invention was made with the aim of eliminating the above-mentioned drawbacks of the conventional technology, and connects independent groups for each common electrode with a high-resistance element having a resistance value greater than that of the heat-generating resistor. The present invention provides a thermal head which prevents a difference in charge between groups and prevents a discharge phenomenon between groups.

The embodiments shown in the drawings will be described below. In FIGS. 3 and 4, reference numeral 20 denotes an insulating substrate, and a common electrode 21 is arranged in parallel on this insulating substrate 20, and individual electrodes 22 are arranged opposite to the common electrode 21.
are arranged side by side at the required pitch. A thin strip-shaped high resistance element 30 is provided between the common electrode 21 and the individual electrodes 22 along the direction in which the individual electrodes 22 are arranged side by side. Further, between the common electrode 21 and the individual electrodes 22, a heat generating resistor 23 is provided for each individual electrode 22. The heating resistor 23 is electrically connected to both the electrodes 21, 22 by overlapping its ends with the electrodes 21, 22, and is also connected to the high resistance element 30 at its center. However,
Adjacent heating resistors 23 are electrically connected through a high resistance element 30. The resistance value of this high-resistance element 30 is several times larger than the resistance value of the heating resistor 23. The reason for this is that when a voltage is applied to the heating resistor selected for recording, the voltage is applied to other heating resistors that are not selected via the high resistance element 30. This is to prevent other heating resistors from generating heat due to the applied voltage and coloring the thermal recording paper.

In this way, the common electrode 21, the heating resistor 23,
Each group A, B, and C consisting of individual electrodes 22 is connected to each other by a high resistance element 30 connected to a heating resistor 23, so even if these groups are charged, each group has the same potential. , the discharge phenomenon no longer occurs between groups as in the conventional case.

Further, in this embodiment, the high resistance element 30 is provided below the heating resistor 23. By the way, in the conventional type, since the heating resistor 11 is under the insulating substrate 10 as shown in FIG.
There is a disadvantage that a space D is created between the two, which impedes heat conduction and reduces the color density of the thermosensitive recording paper 14. In particular, in the case of a thick film method in which the heating resistor 11 is formed by printing and baking a paste-like material, there is a strong tendency for the heating resistor 11 to become concave. On the other hand, in this example,
Since the high-resistance element 30 is disposed under the heat-generating resistor 23 as described above, its surface is flattened, and the contact with the heat-sensitive recording paper is improved, which has the advantage of sufficiently improving the color density even with a small electric power. .

In the above embodiment, the high-resistance element 30 is provided below the heat-generating resistor 23, but the common electrode 21 may be connected to the high-resistance element 40 as shown by the two-dot chain line in FIG. The individual electrodes 22 may be connected by a high resistance element 50. In this case, it is easy to provide the high resistance elements 40 and 50.

As is clear from the above detailed description, according to the present invention, since the electrode groups are connected in the direction in which they are arranged in parallel using the strip-shaped high resistance material provided on the insulating substrate, the structure is simple and the groups can be easily connected even during manufacturing. Therefore, it is possible to prevent the discharge phenomenon caused by the heat generating resistor and prevent damage to the heating resistor. This has the effect of improving the yield and lowering the cost when manufacturing the thermal head.
Further, if a high resistance element is provided below the heating resistor, the surface of the heating resistor can be made flat, so that excellent effects such as sufficient color density can be obtained even with low electric power can be achieved.

[Brief explanation of the drawing]

1 and 2 show a conventional thermal head, FIG. 1 is a plan view thereof, and FIG. 2 is a line 2 in FIG. 1.
FIG. 3 and 4 show an embodiment of the thermal head of the present invention, FIG. 3 is a plan view thereof, and FIG. 4 is a line 4 shown in FIG. 3.
FIG. 20... Insulating substrate, 21... Common electrode, 22...
...Individual electrode, 23...Heating resistor, 30, 40,
50...High resistance body.

Claims (1)

[Scope of Claims] 1. A large number of heating resistors arranged in a straight line on an insulating substrate are divided into groups, and one end of all the heating resistors in the group is connected to a common electrode provided for each group. In the thermal head, a band-shaped high resistance having a resistance value greater than the resistance value of the heating resistor and provided on the insulating substrate is connected to the heating resistor, and an individual electrode is connected to the other end of the heating resistor. 1. A thermal head, wherein at least one of the heating resistor, the common electrode, and the individual electrodes are connected in the direction in which they are arranged side by side. 2. The thermal head according to claim 1, characterized in that a high-resistance element is provided between the insulating substrate and the heating resistor.