JPH01150555A - Thermal head - Google Patents

Abstract

PURPOSE: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, as well as interposing thermal insulating materials between the respective independent electrodes and a ceramic substrate. CONSTITUTION:Independent electrodes 11 are constructed such that they are thinner than a common electrode 2, and thermal insulating materials 12 are interposed between the respective independent electrodes 11 and a ceramic substrate 4. The thermal resistance is made great by making the independent electrodes 11 thin, the occurrence of low temperature regions in the independent electrode section of a heating area being thus prevented. 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. However, since the thermal insulating materials 12 are disposed between the independent electrodes 11 and the ceramic substrate 4, little heat is permitted to be transferred from the independent electrodes 11 to the ceramic substrate 4, and the heat transfer between the respective independent electrodes 11 are also limited. Due to this, the temperature increases fast, and the uniform heating and temperature increase can be realized throughout the heating area. Thus, 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, thereby preventing the adjacent dots from being influenced by the temperature increase.

Description

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

[Conventional technology]

An example of a heating portion of a conventional edge-type thick film thermal head is shown in FIG.

In the figure, symbol (1) indicates the resistor provided at each electrode (21, (3)), (2) indicates the resistor provided at each electrode (2), (
3) is the common electrode connected to the power supply (5), and (3) is the other electrode connected to the switching circuit (
The common electrode (2) and the independent electrode (6) are provided on the ceramic substrate (4), with their ends alternately arranged in parallel.

Further, the common electrode (2) and the independent electrode (2) 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) is turned on as shown in Figure 2B. A current flows through the resistor (1) between the electrode (2) and the independent electrode (ri), and this current causes the resistor (1) to generate heat in the heat generating region shown in the figure, and printing is performed by this heat generation.

However, this heat generation is caused by the image electrodes (2), (3)
and escapes to the ceramic substrate (4) which is in contact with the resistor (1). In particular, the part where the electrode and the heating resistor are in contact with each other,
Since heat is conducted to the electrode and dissipated, the temperature rises slower than other parts, so the temperature distribution of the resistor (1) becomes a temperature distribution having valleys as shown in FIG. 2B.

- If the common electrode (2) and the independent electrode (6) are made thin as shown in Fig. 4, the heat dissipation effect of the electrodes will be eliminated, as shown in Fig. 2C, so that the resistor (1)
Heat also transfers to the non-current parts on the left and right sides of the
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, so if the electrodes are thick, the heat dissipation of the heating resistor portion in contact with the independent electrode will be at the edge of the hole, resulting in insufficient temperature rise in the heating area. Alternatively, if the electrode is thin, heat transfers to the adjacent resistor and the boundary between the heat generating area and non-heat generating area becomes narrow and unclear. This method has problems such as insufficient printing on the dots, or even affecting adjacent dots, making the print unclear.

This invention was made to solve the problem described in L. By preventing heat from escaping from the independent electrode, 1.
The object of the present invention is to obtain a thermal head in which the influence of heat transfer to adjacent dots is reduced by making the temperature within the dot uniform and ensuring sufficient heat radiation to the common electrode.

[Means for solving problems]

In the thermal head according to the present invention, the independent electrode is made thinner than the common electrode, and a heat insulating material is interposed between the independent electrode and the ceramic substrate.

[For production]

Since the independent electrode is made thinner than the common electrode and a heat insulating material is provided between the independent electrode and the ceramic substrate, heat transfer from this part to the ceramic substrate is suppressed, and as a result, the heat generation area The temperature rises faster, and
Since heat transfer to adjacent dots is suppressed, the temperature-increased region and the non-temperature-increased region in the boundary region become clear.

〔Example〕

The present invention will be explained below based on the drawings showing one embodiment thereof. In addition, codes (1), (2), (4) to (6)
Components indicated by are the same as or equivalent to those indicated by the same reference numerals 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.

Further, reference numeral (12) is a heat insulating material interposed between the independent electrode (11) and the ceramic substrate (4). ), and by making the independent electrodes thinner, the thermal resistance is increased and the generation of a low temperature region in the independent electrode portion within the heat generating region is prevented. In addition, by interposing this heat insulating material (12), the top surface height of the independent electrode (11) is made the same as that of the common electrode (2), so that the heating element (1)
The height of the top can be made equal to each dot and within the dot.

Since this invention is configured as described above, when the switching circuit (6) is closed, the current t is transferred to the common electrode (2).
) flows to the independent electrode (11) via the resistor (1). Therefore, the resistor (1) generates heat due to this flowing current, but since the heat insulating material (12) is provided between the independent electrode (11) and the ceramic substrate (4), the second A
As shown in the figure, the heat transfer from the independent electrode (11) to the ceramic substrate (4) is extremely small, and the heat transfer to the independent electrode is also small, so the temperature rises quickly and evenly over the entire heat generating area. As the temperature increases, the temperature distribution of the resistor shows no valleys, and the heat transfer from the resistor (1) to the adjacent dots is enhanced by the heat transfer from the common electrode (2) to the ceramic substrate (4). This reduces the temperature increase of adjacent dots, resulting in uniform printing, rapid temperature rise, and prevention of influence on adjacent dots.

〔Effect of the invention〕

As described below, according to this invention, the independent electrode is made thinner than the common electrode, and a heat insulating material is provided between the independent electrode and the ceramic substrate, so that the temperature of the resistor increases quickly and the independent electrode This has the effect of providing a thermal head in which the transfer of heat from the dot to the ceramic substrate is extremely reduced, the temperature rises quickly, the temperature rise between dots is even, and the influence of temperature on adjacent dots can be prevented. have.

[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 generation area of the figure, Figures 2B and 2C are temperature distribution diagrams of the resistor in the heat generation area of Figures 6 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, (12)...
Insulation. In each figure, the same reference numerals indicate the same or corresponding parts. 1, Nei Antibody 2 ゛ Fut''-Electron tower 4t! Fumyi board 11: Dokusei electric shell 12 Maejuku Makura 2A figure 2B figure Atsushi 2C figure

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 in that the independent electrodes are thinner than the common electrodes, and a heat insulating material is provided between the independent electrodes and the ceramic substrate.