JPH01150556A - Thermal head - Google Patents

Abstract

PURPOSE:To reduce the amount of heat that is absorbed by independent electrodes, as well as to realize the uniform temperature increase in individual dots so as to prevent adjacent dots from being influenced by the temperature increase by constructing independent electrodes such that they become thinner than a common electrode. CONSTITUTION:Independent electrodes 11 are constructed such that they become thinner than a common electrode 2. When a switching circuit 6 is closed, current (i) is allowed to flow from the common electrode 2 to the independent electrodes 11 via a resistance unit 1, and the resistance unit 1 is heated. The temperature of the resistance unit 1 quickly increases. Little heat is permitted to be transferred from the independent electrodes 11 to the ceramic substrate 4, and the uniform heating and temperature increase can be realized throughout a whole heating area. The heat transfer from the resistance unit 1 to adjacent dots is reduced when heat is permitted to be transferred from the common electrode 2 to the ceramic substrate 4, and the temperature increase in adjacent dots is thereby prevented. In addition, the uniform quality of setting is accomplished, and the adjacent dots can be prevented from being influenced by the temperature increase.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a thermal head, and particularly to an edge-type thick film thermal head.

[Conventional technology]

An example of a heated portion of a conventional no-edge type thick film thermal head is shown in FIG.

In the figure, the symbol (ri) is a resistor provided on each electrode (2) (3), and (2) is one of the electrodes (2) (3), which is connected to the electrode (5). common electrode,
(3) is the other electrode, which is an independent electrode connected to the switching circuit (6), and the ends of the common electrode (2) and independent electrode (6) are arranged alternately in parallel to the ceramic substrate
4) Provided above.

Further, the common electrode (2) and the independent electrode (5) are both configured to have the same thickness.

Since the heating section of the thermal head is configured in this way, when printing, when the common electrode (2) is energized and the required switching circuit (6) is energized, the common electrode (2) and the independent electrode ( 5) Resistor (1) between
A current 1 flows through the resistor, and this current causes the resistor to generate heat in the heat generating area shown in FIG. 2B, and printing is performed by this heat generation.

However, this heat generation escapes to the ceramic substrate (4) where the two electrodes (2) [5] and the resistor (1) are in contact.

In particular, since the common electrode (2) and the independent electrode (3) are made of materials with better thermal conductivity than the ceramic substrate, such as gold or aluminum, they generate a large amount of heat as shown in Figure 2B. radiates heat through the common electrode (2) and the independent electrode (3).Therefore, the temperature distribution of the resistor (1) becomes a temperature distribution having valleys as shown in FIG. 2B.

On the other hand, if the common electrode (2) and the independent electrode (3) are made thin as shown in FIG. 4, then as shown in FIG. Since heat conduction is reduced, a large amount of the heat generated by energization is not absorbed into the electrode (2) <3>.
Heat transfer to the non-current parts on the left and right sides of the resistor increases,
Therefore, as shown in the distribution diagram in the figure, the temperature distribution gradually tapers toward the non-heated portion, which is the adjacent dot.

[Problem that the invention seeks to solve]

Conventional devices are configured and operate as described above, and therefore, there may be an area where the temperature rises in an unstable manner within one heat generating area, or the boundary between one heat generating area and a non-heat generating area may become sloppy and unclear, resulting in printing problems. However, there have been problems in that some parts of one dot may be insufficiently printed, or that adjacent dots may be affected, making the printing unclear.

This invention was made in order to solve the above-mentioned problems, and aims to make the temperature within one dot uniform and reduce the influence of heat transfer to adjacent dots, thereby obtaining an "l--maru head". do.

[Means for solving problems]

In the thermal head according to the present invention, the independent electrode is thinner than the common electrode.

[For production]

Because the independent electrodes are thinner than the common electrodes,
There is little heat absorption at the independent electrode section (and sufficient heat absorption at the common electrode section), so heat is generated uniformly over the entire heat generating area, and heat transfer to adjacent dots is also small, making it extremely difficult for the temperature of adjacent dots to rise. It is possible to make the boundary between the temperature-raising region and the non-temperature-raising region extremely clear.

〔Example〕

The present invention will be explained below based on the drawings showing one embodiment thereof. Note that the items indicated by the symbols (1), (2), (4) to (6) are the same as or equivalent to those indicated by the same symbols in the conventional device.

In FIG. 1, reference numeral (11) is an independent electrode that is thinner than the common electrode (2), for example, about 0.4 μm when the common electrode (2) has a thickness of about 4 μm. The connection to the switching circuit (6) is the same as in the conventional case.

This invention is configured as described above.

When the switching circuit (6) is closed, []i flows from the common electrode (2) to the independent electrode (11) via the resistor (1). Therefore, the resistor (1) generates heat due to this flowing current, but the current is as shown in FIG. 2A.

The temperature rises rapidly, and the heat transfer from the independent electrode (It) W to the ceramic substrate (4) is also small (1) The resistor temperature distribution heats evenly over the entire heat generating area, and the temperature rises without any valleys. In addition, heat transfer from the common electrode (2) to the ceramic substrate (4) reduces the heat transfer from the resistor (1) to the adjacent dots, suppressing the temperature rise of the adjacent dots, and these results , homogenizes the print and prevents it from affecting adjacent dots.

[Devising the invention]

As described above, according to the present invention, since the independent electrodes are made thinner than the common electrodes, it is possible to obtain a thermal head that can uniformly raise the temperature and prevent the influence of temperature on adjacent dots. are doing.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of one embodiment of the invention, and FIG. 2A is a perspective view of an embodiment of the invention.
Figures 2B and 2C are temperature distribution diagrams of the resistor in the heat generating area of the figure, Figures 2B and 2C are temperature distribution diagrams of the resistor in the heat generating area of Figures 3 and 4, respectively, showing the conventional device. The figures are perspective views of two examples of heating parts of conventional thermal heads. (1) Resistor, (2) Common electrode, (4) Ceramic substrate, (11) Independent electrode. In each figure, the same reference numerals indicate the same or corresponding parts. Figure 1 18: m-body 2 Romoshi? ,,li 4 tU,gu 77 sword qmo 11 raccoon 1 electric fall 2A figure 3 figure 4

Claims (1)

[Claims] In an edge type thick film thermal head in which common electrodes and independent electrodes are arranged alternately on a ceramic substrate,
A thermal head characterized by an independent electrode that is thinner than a common electrode.