JPS62286760A - Thermal head - Google Patents

Abstract

PURPOSE:To realize recording having uniform density, by providing slits to heat generating resistors so that the widths thereof change so as to become larger toward the center of the heat generating resistor row. CONSTITUTION:A large number of heat generating resistors 2A-2G are linearily arranged on a substrate 1 having heat resistance and an insulating property so as to be adjacent to each other at a definite interval and electrodes 3A-3G are formed on the same substrate 1 from the terminals of the heat generating resistors 2A-2G in order to connect said resistors to the outside at the left-hand peripheral part of said substrate 1. Slits are provided to the heat generating resistors at the central parts thereof so that the widths thereof change so as to become larger toward the center of the heat generating resistor row and respective one terminals of the heat generating resistors divided into two groups are connected in series by the connection electrodes 3A-3G and the other terminals thereof are each formed as one heat generating element by connection electrodes 4A-4G.

Description

Detailed Description of the Invention λ Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a thermal head used in a thermal printer or the like, and particularly to a shape of a heating resistor of a thermal head having a relatively small number of heating resistors. It is something.

[Conventional technology]

Thermal heads are generally linear as each other! Il!
i! Current is passed through a plurality of tiny heat-generating resistors arranged on top of each other, and dot-shaped recordings are repeatedly made in response to the heat generated by the . In recent years, with the development of integrated circuit technology,
A heating resistor and a conductor for connecting it to the outside are formed on a substrate such as a glazed ceramic.

FIG. 3 is a plan view showing a conventional example, in which a plurality of heating resistors 2A to 2G are arranged in a straight line and adjacent to each other with a certain gap provided on a substrate 1 having heat resistance and insulating properties. In addition, electrodes 38 to 3G are formed on the same substrate from the ends of the heating resistors 2A to 2G in order to connect them to the outside at the left peripheral portion in FIG. In addition, there is a slit of a constant width in the center of the heating resistor, which is divided into two parts, one end of which is connected in series to the N power supply and ground through connection electrodes 3A to 3GK, and the other end connected to the N power supply and ground through connection electrodes 4A to 4G. It is formed as one heating element.

[Problem that the invention seeks to solve]

Since the resistance values of the heating resistors of the conventional thermal head described above are all the same, the power consumption and the amount of heat generated are uniform when the same voltage is applied.

However, heat dissipation was poor at the center of the row of heating resistors, and in actual printing, the print density was high in the middle due to the heat circulating from each heating resistor, resulting in characters etc. being crushed.

Another drawback was that heat easily escaped from the outside of the row of heating resistors, and the top and bottom of the print became thin, leading to poor connections between the top and bottom dots at line breaks.

The above-mentioned problem becomes conspicuous in the case of a mechanism in which printing is performed by pressing a thermal head against a round plate, because the pressure at the center of the heating resistor row is high and the pressure at the outside is low.

As a countermeasure to this problem, there is a method of increasing the area of the heating resistors at the top and bottom rows of the heating resistor array, but this method cannot completely correct the above-mentioned drawbacks.

[Means for solving problems]

In the thermal head according to the present invention, a slit is provided above the heating resistor, the width of which increases as it approaches the center of the row of heating resistors.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a plan view showing an embodiment of the present invention, in which a plurality of heating resistors 2 are placed on a substrate 1 having heat resistance and insulation properties.
A to 2G are arranged in a straight line and adjacent to each other with a certain gap, and each heating resistor 2A is connected to the outside at the left peripheral part in FIG.
Electrodes 3A to 3G are formed on the same substrate from the end of 2G. In addition, a slit is provided at the center of the heating resistor, the width of which changes as it approaches the center of the heating resistor row, and one end of each of the two divided heating resistors is connected to a connecting electrode. 3A to 3G are connected in series, and the other end is formed as one heating element by connecting electrodes 48 to 4G.

The resistance value of the heating resistor of the thermal head mentioned above increases toward the center of the heating resistor row and decreases toward both ends, so when the same voltage is applied, the power consumption and heat generation amount are the same as those of the heating resistor row. It gets smaller towards the center and gets bigger towards the ends.

Based on these facts, by appropriately selecting the amount of change in the width of the slit in the heating resistor row, it is possible to effectively compensate for heat accumulation at the center of the heating resistor row and heat dissipation at both ends, thereby reducing the amount of heat at the center of printing. It can be seen that the characters are not crushed and the print density decreases at the top and bottom of the print.

Note that in the length-round head according to the present invention, the resistance value is adjusted by the width of the slit in the center of the heating element for printing one pixel, so the dot pitch does not differ.

In addition to the embodiment shown in FIG. 1, it can also be applied to a thermal head in which a common electrode 5 is formed on a substrate that connects a heating resistor to the outside of the common connection as shown in FIG. Not even.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, the heat generation state of the heating resistor is made uniform, recording of uniform density is realized, and remarkable effects can be obtained when applied to thermal heads for various uses.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing one embodiment of the present invention, FIG. 2 is a plan view showing another embodiment of the invention, and FIG. 3 is a plan view of a conventional example. 1...Substrate, 28-2G...Heating resistor, 3A-3G...Electrode, 4A-4G...
・・Connecting electrode, 5・・・・・1,・Representative patent attorney El Uchihara as well.

Claims (1)

[Claims] In a thermal head having a plurality of heating resistors arranged adjacent to each other on an insulating substrate, and an electrode formed on the insulating substrate for connecting an end of the heating resistor to the outside, the heating resistor A thermal head characterized by having a slit on the body that becomes wider as it gets closer to the center of the row of heating resistors.