JPS6241053A - Thermal head - Google Patents

Abstract

PURPOSE:To provide a thermal head which enables sharp printing to be obtained through the improvement of abrasion resistance of a heating element by forming multiple annular heating elements on the external circumference of a columnar insulator held in freely rotating fashion. CONSTITUTION:Multiple annular heating elements 2 are arranged in parallel with the axial direction of a columnar insulator 1 on the external circumference of the insulator. The annular heating element 2 is composed of a conductive layer 3 and a heating resistive layer 4. Paper 22 is set on a platen 6 and a carrier 7 is moved to the right with the running of a ribbon 16 from the right to the left side of the carrier 7. During this process, printing is performed by outputting a printing signal to the base of a transistor from a control circuit. However, the calorific value of the closest part to the platen 6 of the annular heating element 2 reaches the maximum level and said part forms a single dot. At that time, the insulator 1 is rotated counter clockwise by the ribbon 16. The hottest part of the annular heating element 2 leaves the paper 22 and the ribbon 16 quickly to provide sharp print without ink run. In addition, the annular heating element 2 indicates an improved abrasion resistance because it is not abrased by the paper 22 or ribbon 16 on account of the rotation of the insulator 1.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a thermal head.

2. Description of the Related Art A conventional thermal head is generally formed by arranging a plurality of heating elements in a straight line on a flat insulating substrate.

Problems to be Solved by the Invention However, since the friction when the heating element slides on the paper or ribbon is sliding friction, the frictional resistance is large, and the heating element wears quickly and is easily soiled. Furthermore, since the contact time of the heating element with the ribbon is long for each character printed, the printing is unclear.

This invention was made in view of these points.

The purpose is to improve the wear resistance of the heating element and to print a thermal head that can print clearly.

Means for Solving the Problems In the present invention, a plurality of annular heating elements 2 are formed around the outer periphery of a cylindrical insulator 1 that is rotatably held.

The working insulator 1 is rotated and a desired annular heating element 2 is energized to form a dot on the paper 22. At this time, the insulator 1 rotates. Therefore, the frictional resistance of the annular heating element 2 against the ribbon 16 or the paper 22 is small due to rolling friction, and the wear resistance of the annular heating element 2 is improved, and the heating part of the annular heating element 2 is quickly separated from the ribbon 16 or the paper 22. As a result, clear printing with no smearing can be achieved.

Example An embodiment of the present invention will be described based on the drawings.

Reference numeral 1 denotes a cylindrical insulator, and a plurality of annular heating elements 2 are formed on the outer periphery of the insulator 1 and arranged in parallel to the axial direction of the insulator 1. The annular heating element 2 includes a conductive layer 3 and a heating resistance layer 4.
A brass bearing 5 is inserted into the inner periphery of the bearing.

Next, the structure of the printer will be explained. A carrier 7 that moves along the axis of the platen 6 has a support 1o having a ribbon guide 8 and a support shaft 9 that rotatably holds the bearing 5 of the insulator 1 in a direction in which it moves away from the platen 6 by a spring 11. It is held movably by being biased towards it. Further, the carrier 7 holds an electromagnet 13 having a plunger 12 that pushes the support 10 toward the platen 6 . Furthermore, the carrier 7 rotatably holds a common electrode 14 and also holds individual electrodes 15 that resiliently contact each of the annular heating elements 2. Furthermore, although not shown, the ribbon 16 is housed in a cassette case that is detachably attached to the carrier 7.

An ink layer 18 that dissolves when heated is formed on the surface of a long film 17, and a conductive layer 19 is formed on the back surface.

Each annular heating element 2 is connected to one pole of a power source via an individual electrode 15, and is also connected to the collector of an NPN transistor 2o. The emitter of the transistor 2o is connected to multiple poles of the power source via the conductive layer 19 of the ribbon 16 and the common electrode 14. The base of the transistor 20 is connected to a control circuit 21 that outputs a print signal.

In such a configuration, in the process of setting the paper 22 on the platen 6, moving the carrier 7 to the right, and running the ribbon 16 from the right side of the carrier 7 to the left side, the base of the transistor 2o corresponding to the desired annular heating element 2 is control circuit 2
Printing is performed by outputting a printing signal from 1, and the portion of the annular heating element 2 closest to the platen 6 generates the maximum amount of heat, and one dot is formed in this portion. At this time, the insulator 1 is rotated by the ribbon 16 in the direction of the half-hour hand.

Therefore, the highest heat generating portion of the annular heating element 2 quickly separates from the paper 22 and the ribbon 16, resulting in clear printing without smearing. Further, since the annular heating element 2 is not rubbed by the paper 22 or the ribbon 16 due to the rotation of the insulator 1, the wear resistance can be improved.

Note that the cylindrical insulator includes insulators other than those having a cylindrical shape provided with the support shaft 9. In this case, the bearing 5 may be provided on the support body 10.

Effects of the Invention Since the present invention is configured as described above, by rotating the insulator on which the annular gas generator is formed, the frictional resistance of the annular heating element against the ribbon or paper is reduced, thereby improving wear resistance. You can do it again.

Since the heat-generating portion of the annular heat-generating element quickly separates from the ribbon or paper, it is possible to obtain clear printing without smearing.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a longitudinal sectional front view of the main part, and FIG. 2 is a plan view of the main part. FIG. 3 is a plan view showing the overall structure on a reduced scale, and FIG. 4 is a circuit diagram.

Claims (1)

[Claims] A thermal head characterized in that a plurality of annular heating elements are formed on the outer periphery of a rotatably held cylindrical insulator and arranged in parallel to the axial direction of the insulator.