JPS58136462A - Thermal head - Google Patents

Abstract

PURPOSE:To enable the prevention of deterioration in a recording image with an even temperature distribution by providing a heat generating resistor with a temperature rise checking means attached and a lead electrode thereof at the center, in a heat-sensitive recording thermal head. CONSTITUTION:When a doughnut-shaped heat generating resistor 11 hollowed at the center thereof is energized through a lead electrode 2, heat is generated only in the peripheral part, none at the center being hollowed, making the temperature distribution of a body to be heated almost uniform. If a higher resistance is provided at the center, for example, by making the part thin, burying a material 3 of a large heat capacitance there or bringing a material 5 of a good heat conductivity in contact with the center of the heat generating resistor 11, the same effect can be obtained. This can extend the life of the heat generating resistor by preventing deterioration in the recording image.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal head κ using a heat-sensitive brass κ.
In particular, it relates to a nine-seater head κ that makes the heat generation temperature uniform.

The shape of the heating element of conventional thermal heads has generally been a square in a circle.

Figure 1 is a schematic plan view showing the inner cavity of a conventional energizing element, stripe 2.
The figure shows the heated object (
FIG. 2 is a diagram showing the temperature distribution of an ink donor sheet, a thermosensitive recording medium, etc.).

In FIG. 1, 1 is a heating element, and 2 is a lead electrode thereof.

However, in a nine-street head using such a conventional heating element 1, when heat is generated, the temperature at the center of the heating element 1 rises sufficiently to reach a high temperature.
In the peripheral area, it does not rise much (see Figure 2).

Ninth, an uneven temperature rise κ occurred between the center and the periphery, which made the temperature distribution of the thermal head uneven during recording and deteriorated the recorded image quality, shortening the life of the heating element. It had some drawbacks.

An object of the present invention is to eliminate such drawbacks and provide a thermal head with uniform temperature distribution during recording.
be.

In order to achieve the above object, the present invention suppresses the rise in temperature at the center of the heating resistor constituting the heating element of the thermal head, so that the temperature rise of the entire heating resistor is almost uniform. It is distinctive in that it has been made to become so.

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 3 is a schematic plan view of one embodiment of the present invention, and FIG.
The figure shows the temperature distribution of the heated object when recording is performed by energizing it, and the vertical axis of the figure shows the temperature.

In the KS diagram Kk, 11 is a donut-shaped heating resistor with a cutout in the center, and 2 is its lead electrode.

When the heating resistor 11 configured as described above is energized, since the central part of the heating resistor 11 is hollowed out, this part does not generate heat, but only the peripheral part generates heat.

Therefore, as shown in FIG. 4, the temperature distribution of the object to be heated becomes approximately #1 uniform.

In the above embodiment, the donut-shaped heat generating resistor with a hollowed-out central portion is used, but is not limited to this, as long as the central portion has a higher resistance than the peripheral portion. For example, it is possible to use a heating resistor with a thinner central portion.

FIG. 5 is a schematic sectional view of the II2 embodiment of the present invention.

In the figure, 11 is a heating resistor formed on a part of the upper surface of the insulating substrate 4, and S is a material provided at the center of the heating resistor 11, which has a larger heat capacity than the heating resistor 11. .

When the heating resistor 11 configured as described above is energized, as described above, since the central portion of the heating resistor 11 is provided with a substance having a larger heat capacity than the heating resistor 11, the central portion As shown in FIG. 4, the temperature distribution of the heated object becomes almost uniform.

IN, 4E is in FIG. 0 which is a schematic sectional view of the jI5I5 embodiment of the present invention, 11 is a heating resistor formed on a part of the upper surface of the insulating substrate 4, and 5 is a central part of the heating resistor 11. It is a material with excellent thermal conductivity that is placed so that the top surface is partially in contact with the bottom surface.

When the heating resistor 11 configured as described above is energized, as described above, a portion of the bottom surface of the central portion of the heating resistor 11 is
Since the upper surfaces of the material 5 having excellent thermal conductivity are provided in contact with each other, heat dissipation in the central portion is improved and temperature rise in that portion is suppressed. As a result, as shown in FIG. 4, the temperature distribution of the heated object becomes almost uniform.

As described above, the present invention suppresses the temperature rise in the central part of the heating resistor constituting the heating element of the thermal head, thereby making the temperature rise in the central part and the peripheral part almost equal. It is possible to make the temperature distribution uniform during recording with the i-mill head, which allows recording 1i
ii) There is an advantage that deterioration of the product can be prevented.

Furthermore, there is an advantage that the life of the heating resistor can be extended.

[Brief explanation of drawings]

Figure 1 is a schematic plan view showing an example of a conventional heating element;
The figure is a diagram showing the temperature distribution of the heated body during recording, the fan 3 figure is a schematic plan view of an embodiment of the present invention, and the @4 figure is a diagram showing the temperature distribution of the heated body during recording. Figure 5 is a schematic cross-sectional view of the second embodiment of the cocoon of the present invention. Figure Jl14 is a schematic cross-sectional view of the jI3 practical example of the present invention. DESCRIPTION OF SYMBOLS 1... Heating element, 2... Lead electrode, S... Substance with large heat capacity, 4... Insulating substrate, 5... Substance with excellent thermal conductivity, 11... Heating resistor Agent Benshio Michihito Hiraki 1 other person 11 Figure 1 O 5F21 Figure 3 1 Fang 4 Figure 16 Figure 1

Claims (4)

[Claims] (1) An insulating substrate, a pre-heating resistor provided on a part of the upper surface of the insulating substrate and provided with temperature rise suppressing means in the center, and lead electrodes of the heating resistor. A thermal head featuring (2) *The round head according to claim 8, item 1, wherein the central portion of the heating resistor has a higher resistance than the peripheral portion. (3) The above-mentioned claim 11 refers to the fact that the heat capacity of the central part of the heat-threatening resistor is larger than that of the peripheral part.
Sumal head described in J11m. (4) Patent claim 11j characterized in that heat dissipation in the central part of the heat resistor is improved compared to the peripheral part.
l Thermal head P6 described in item 1