JPH0626918B2 - Method for manufacturing thermal print head - Google Patents

Description

The present invention relates to a method for manufacturing a thermal print head.

(Prior Art) In this type of thermal print head, it is known that if the density of the heating dots is increased, the image quality is improved. Therefore, there is a strong demand for higher density.

FIG. 3 shows an example of a conventional pattern, which is a strip-shaped resistor R.
The common electrode C and the individual electrode S are alternately arranged so as to cross the line. According to this configuration, one heating dot is configured by the two partitioning resistor portions M adjacent to each other of the resistor body partitioned by the adjacent electrodes.

According to this configuration, each heating dot has a half of the partition resistance portion density. Therefore, in order to increase the density of the heating dots, it is necessary to increase the partition resistance portion density. With such a configuration, the dot density is limited to 8 dots per mm.

FIG. 4 shows another conventional example, in which a resistor R formed separately from each other has a common electrode C at one end and an individual electrode S at the other end. Each of them is formed by stacking them. According to this, each heating dot is constituted by the individual resistor R.

However, when each resistor R is formed of a thick film, each resistor R and the individual electrode S are formed so as to overlap each other.
The resistor R may flow from above, and adjacent resistors R may come into contact with each other. Therefore, the adjacent resistors R cannot be sufficiently brought close to each other, and therefore, it is not possible to expect much increase in the density of the heating dots. Specifically, the limit is 6 dots per mm.

(Problems to be Solved by the Invention) An object of the present invention is to make it possible to easily increase the density of heating dots without requiring the pattern to be too fine.

(Means for Solving the Problem) The present invention forms a plurality of electrodes on one side edge and the other side edge of a strip-shaped heating resistor made of a thick film so as to be paired with each other, and By applying a pulsed high voltage between the electrodes that become a pair of electrodes, the resistance portion for the heating dots existing between the pair of electrodes is made lower than the resistance portion between the adjacent electrodes. By doing so, the pair of electrodes are substantially opened or isolated from the adjacent electrodes.

It is generally known that when a pulsed high voltage having a sufficiently narrow width is applied to a thick film resistor, the resistor does not generate heat and the resistance value becomes low. This is because when the resistive particles forming the resistance paste are covered with some kind of insulating film such as an oxide film and are in contact with each other through this oxide film, the pulsed high voltage as described above is applied. Then, due to the high voltage, the oxide film causes discharge breakdown and the particles come into direct contact with each other.

Therefore, it is considered that the resistance value decreases. Specifically, for example, when a pulse of 1000 V / 0.1 mm, 3 ns is applied, the resistance value may be reduced to about half.

The decrease in the resistance value between the paired electrodes in this way means that the resistance value between the adjacent electrodes becomes a pair with respect to the adjacent electrodes even if the resistance value of the resistor portion does not change at all. Thus, the existing electrodes are equivalently opened or isolated.

Therefore, even if the space between adjacent electrodes is made sufficiently narrow,
The degree to which the current supplied between the pair of electrodes flows toward the adjacent electrode is sufficiently small that it is not affected by the application. Thus, even if the space between the adjacent electrodes is made sufficiently small, no trouble will occur. As a result, the heating dots can be manufactured with high density.

(Embodiment) An embodiment of the present invention will be described with reference to the drawings. Reference numeral 1 is a substrate made of an insulating material such as ceramics, and 2 is a resistor for heat generation, which is formed by a thick film on the surface of the substrate 1, and is formed in a long strip shape. Reference numeral 3 denotes a plurality of electrodes formed on one side edge of the resistor 2 and 4 denotes a plurality of electrodes formed on the other side edge. The electrodes 3 and 4 are paired with each other, and the resistor portion 2A between the electrodes 3 and 4 is used as a heating dot.

In this case, the electrodes 3 and 4 are simply overlapped with the resistor 2, and there is no case where resistors or the like are individually overlapped on the surface as shown in FIG. There is no problem in forming them so that they are sufficiently close to each other.

In the illustrated example, the resistor 2 is formed on the surface of each electrode in a superposed manner, but by reversing this, the resistor 2 is first formed on the surface of the substrate 1, and then each electrode is formed on the surface of the resistor 2. You may make it overlap and form.

Then, according to the present invention, a pair of electrodes 3, 4
In the meantime, a high voltage pulse is applied to reduce the resistance value of the resistor portion 2A between the electrodes 3 and 4. Even if the resistance value of the resistor portion 2B between the adjacent electrodes does not change due to the decrease in the resistance value, the resistor portions 2A adjacent to each other by the resistor portion 2B are equivalent to each other and are substantially open or isolated. It will be done.

Therefore, at the time of printing, even if electric power is supplied between the electrode and the electrode 4, it is less likely that a current will flow toward the other electrodes adjacent to the electrodes 3 and 4, and the space between the electrodes 3 and 4 is reduced. Only the resistor portion 2A will generate heat. It has been confirmed that the dot density formed by this method can be up to 16 dots per mm.

Although not shown in the figure, it goes without saying that the surfaces of the resistors and electrodes are actually coated with glass or the like. Further, after the treatment as described above, it is preferable that one electrode, for example, the end portion of the electrode 3 is collectively connected and used as a common electrode.

(Effects of the Invention) As described in detail above, according to the present invention, the resistance between the paired electrodes is reduced, so that the electrodes are equivalent to each other. In addition, since the electrodes are almost opened or isolated, the adjacent electrodes can be formed sufficiently close to each other, and therefore, it is possible to increase the density of the heating dots.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of the present invention, FIG. 2 is a sectional view of the same, and FIGS. 3 and 4 are plan views of a conventional example. 2 ... Resistor, 2A, 2B ... Resistor part, 3, 4 ...
electrode,

Claims (1)

[Claims] 1. A plurality of electrodes are formed on one side edge and the other side edge of a strip-shaped heat-generating resistor made of a thick film so as to be paired with each other, and pulse-shaped electrodes are formed between the paired electrodes. By applying a high voltage of, the resistance portion for the heating dot existing between the paired electrodes is made lower in resistance than the resistance portion between the adjacent electrodes. Method for manufacturing a thermal print head.