JPS62234950A - Thermal head supporting mechanism - Google Patents

Abstract

PURPOSE:To obtain high-quality printing by supporting a thermal head with a supporting shaft arranged on a plane containing the center line of a string of thermal elements and the center shaft of the thermal head, setting the thermal head with the supporting shaft in freely rotatable fashion and making the relative variable. CONSTITUTION:A thermal head 1 is supported on one end of a bracket 9 by a thermal head supporting shaft 3 contained in a plane including the center line C-C of a string of thermal elements 2 and the center shaft Y-Y of a platen roller 4. Further the thermal head is set in such a way that is rotates freely around a center shaft X-X as indicated by an arrow D-D. The lower end of the bracket 9 is connected to a carrier ASSY 6 in freely rotatable fashion by means of a rotary supporting shaft 7. At the bottom of the rotary supporting shaft 7 of the bracket 9, a spring 8 is provided, which is pulled in Z direction by means of a solenoid, thus generating the pressing force of the thermal head 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of a color development type or transfer type thermal printer, and particularly to a thermal head support mechanism.

[Prior Art] The structure of a conventional thermal printer is shown in FIG. In the figure, 10 is a thermal head, 12 is a thermal head 1
0 is a heating element row, 13 is a thermal head support shaft, 14 is a platen roller, 16 is a carrier ASSY, and 17 is a guide shaft for the carrier ASSY.

Here, the rotation center axis x-x of the thermal head l includes a center line C-C passing through the center of one heating element row 2 and perpendicular to one heating element row 2, and a central axis Y-Y of the platen roller 4. It is located at a distance from the plane. The thermal head support shaft 13 is fixed to the carrier ASSY 16, and the relative position of the platen roller 14 to the center axis Y-Y is also fixed.

[Problems to be Solved] In the conventional thermal head support mechanism described above, the rotation center axis x-x of the thermal head 1 is separated from the heating element row 2, and the relative position with respect to the platen center axis Y-Y is fixed. Therefore, as shown in FIG. 4(a), the mechanical conditions are set so that when recording paper S-t of thickness dl is set, the heating element row length B1 is located within the printable pressure range A1. Even if the thickness dz (d+
<dz) When the recording paper 5-2 is set, the contact angle 0 of the thermal head 1 changes from 01 to 02 (θ+<(7z)
This has the drawback that the heat generating element row length B1 protrudes outside the printable pressure range A1, and density unevenness and chipping are likely to occur in the printed image. In addition, if the pressure contact force of the thermal head 10 is increased to avoid this, the rigidity of the mechanism will be required, which will increase the size of the device and increase the cost. Thermal printers suffer from various serious drawbacks such as wrinkles in the ink ribbon.

[Means for Solving the Problems] The thermal head support mechanism of the present invention which solves the above-mentioned conventional problems has a thermal head in which a plurality of heating elements are arranged in a row, and a platen roller sandwiching and pressurizing a recording medium. In a thermal head support mechanism of a color development type or transfer type serial thermal printer that performs recording by moving the thermal head in the digit direction of the recording medium according to print information, the thermal head is arranged at a center line orthogonal to a row of heating elements. and the central axis of the platen roller, and the thermal head is rotatable with respect to the support shaft, and the thermal head is supported by a support shaft located on or near a plane including the central axis of the platen roller, and the thermal head is rotatable with respect to the support shaft, and The configuration is such that the relative position with respect to the main body is variable.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings showing a preferred example.

FIG. 1 is an external perspective view of a thermal head support mechanism according to an embodiment of the present invention. In fig.

1 is a thermal head, 2 is a heating element row of the thermal head L, 3 is a thermal head support shaft, 4 is a platen roller,
6 is a carrier ASSY, 7 is a rotation support shaft, 8 is a spring, and 9 is a bracket.

The thermal head l is connected to the center line C- of the heating element row 2.
It is supported at one end of the bracket 9 by a thermal head support shaft 3 included in a plane including C and the center axis Y-Y of the platen roller 4, and is rotatable around the center axis xx as shown by an arrow D-D. It has become. Further, the lower end of the bracket 9 is rotatably connected to the carrier ASSY 6 by a rotation support shaft 7. A spring 8 is provided further below the rotation support shaft 7 of the bracket 9.
This spring 8 is pulled in the Z direction by a solenoid or the like (not shown) to generate a pressing force for the thermal head 1.

According to the thermal head support mechanism of this embodiment, the recording paper 5-- has a thickness of dl as shown in FIG.
1, if the center of the heating element row B2 and the center of the printable pressure range A2 are set to match,
Even when the recording paper 5-2 with the thickness dz (d+<dz) is set in FIG. 2(b), the center deviation Δ2 between the printable pressure range A2 and the heating element row length B2 is extremely small, and the heating element row length B2 is extremely small. It becomes easy to keep the pressure within the printable pressure range A2. This is because even when the paper 5-2 with a thickness of dz is set, the thermal head l rotates around the central axis x-X of the thermal head support shaft 3, and the contact angle of the thermal head l hardly changes. There will be no.

[Effects of the Invention] As explained above, the present invention supports a thermal head on a support shaft disposed on or near a plane including the center line of the heating element array and the center axis of the platen, and that the thermal head supports this support shaft. In addition to being rotatable relative to the center axis of the platen, the relative position between the support shaft and the center axis of the platen can be changed to prevent uneven shading, chipped images, wrinkles in the ink ribbon, etc. even on recording paper of any thickness. It is possible to achieve good printing quality without causing any problems, and furthermore, the wear life of the thermal head can be further extended.

[Brief explanation of drawings]

FIG. 1 is an external perspective view of a thermal head support mechanism according to an embodiment of the present invention, and FIGS. 2(a) and (b) are side views for explaining the operation of the thermal head support mechanism shown in FIG. 1, respectively. 3 are external perspective views of a conventional thermal head support mechanism. FIGS. 4(a) and 4(b) are side views for explaining the operation of the conventional thermal head support mechanism. ■ = Thermal head 2: Heat generating element row 3: Thermal head support shaft 4 Nib platen roller 5: Recording paper 6: Carrier ASSY 7: Support shaft 8 Spring 9 Nib bracket

Claims (1)

[Claims] The recording medium is sandwiched and pressurized between a thermal head with multiple heating elements arranged in a row and a platen roller.
In a thermal head support mechanism of a color development type or transfer type serial thermal printer that performs recording by moving the thermal head in the digit direction of the recording medium according to print information, the thermal head is arranged at a center line orthogonal to a row of heating elements. and the central axis of the platen roller, and the thermal head is rotatable with respect to the support shaft, and the thermal head is supported by a support shaft located on or near a plane including the central axis of the platen roller, and the thermal head is rotatable with respect to the support shaft, and A thermal head support mechanism characterized in that its relative position with respect to the thermal head support mechanism is variable.