JPH0357674A - Thermal head - Google Patents

Abstract

PURPOSE:To obtain a recording image of good quality by making the relative position of a heat generating part and a platen roller constant by bringing the shaft of the platen roller into contact with the positioning means of a thermal head by an attached preload means. CONSTITUTION:A spring 10 provided between a frame 8b and a thermal head 1 presses the thermal head 1 in the direction shown by an arrow B. That is, the pressing force of the spring 10 allows the thermal head 1 to directly act on the shaft 4 of a platen roller 3 through a collar 5 to perform the positioning of a heat generating part 2 and the platen roller 3. When the platen roller 3 is rotated in the direction shown by an arrow A by a drive source, since the thermal head 1 is pressed in the direction shown by an arrow C by a spring 7, the recording paper inserted between the thermal head 1 and the platen roller 3 is driven in the direction shown by the arrow B. Since preload is applied to the thermal head 1 in the direction shown by the arrow B by the spring 10, the inside surface 6b of a positioning metal fitting 6 is evenly brought into contact with the shaft of the platen roller. Therefore, the transfer position of the heat generating part 2 and the platen roller 3 is kept constant and a recording image of good image quality is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a positioning device for a thermal head used in a facsimile machine, etc., and particularly to a positioning device thereof.

[Conventional technology]

Figure 3 (g) is a schematic sectional view of a conventional thermal head, and Figure 3 (c) is a partially enlarged view of (1) the thermal head, (2) the thermal head. (1
), (8) is the platen roller that comes into contact with the heat generating part (2), (4) is the shaft of the ti platen roller (8),
(5) is a collar that is assembled into the shaft (4), and (6) is an inner surface (6a) that is fixed to the thermal head (1).
(b) is a positioning metal fitting that aligns the heat generated by the thermal head (1) a (2) and the axis of the platen roller (8): r5 by bringing the collar (6) into contact with the collar (6); (8) is the spring that presses the frame, (9) is the platen roller (8).
), and the recording paper is printed by the thermal head (1).
) is the outer diameter s of the shaft (4) (dz) is the collar (5)
(d3) is the outer diameter of the collar (6). Note that the collar (5) is made of a softer material than the shaft (4) and does not rotate during operation.

Next, the operation will be explained. In the thermal head (1), the platen roller (8) and the recording paper (9) are evenly abutted in the longitudinal direction of the thermal head perpendicular to the plane of the paper by the pressure of a spring (7). Also, this spring (7) presses the thermal head (1) and the platen roller (8) in the direction of arrow C so that they do not pulsate due to the rotation of the platen roller by a drive source (not shown) and the scanning of the recording paper, so that the thermal head (1) and the platen roller (8) are pressed in the direction of arrow C to prevent them from pulsating. At the same time, printing performance is improved.

As shown in FIG. 3, when the platen roller (8) rotates in the eight directions of arrows, the recording paper (9) is driven in the direction of arrow B, and the heat generating section (2) generates heat according to a signal from a heat generating control section (not shown). It is printed and recorded by.

In the figures, the overturn prevention mechanism of the thermal head (1) is not shown. , [Problem to be solved by the invention] Conventional thermal head positioning is performed using positioning metal fittings (6
), the inner surfaces (6a) and (6b) of the platen roller (
8) by coming into contact with the force collar (6) built into the shaft (4), so the following gaps on the device assembly structure: Outer diameter (cH) and collar - (6) inner diameter (d2) (2) outer diameter (d3) of collar (6) and positioning metal fitting (6)
) and the difference from the interval (B) during operation due to misalignment of the axis in the direction of arrow B. In machines where recording operations such as facsimiles are performed intermittently, the heat generating part ( 2) There is a problem in that the axial misalignment of the platen roller (3) occurs in a pulsating manner, resulting in deterioration of the recorded image quality.

This invention was made to solve the above-mentioned problems, and an object thereof is to obtain a thermal head that can record images of good quality.

[Means to solve the problem]

The thermal head according to the present invention has a positioning means for aligning the axes of the heat generating part and the platen roller, and the positioning means is brought into contact with the platen roller shaft by the preload means, thereby eliminating backlash of the thermal head during operation. This is what I did.

[Effect]

In the thermal head according to the present invention, the platen roller shaft and the positioning means of the thermal head are brought into contact with each other by the attached preload means, so that the relative position between the heat generating part and the platen roller is constant, and recording images of good image quality can be obtained. is obtained.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1(a) to (/1).

The parts whose explanations are omitted are the same as those of the conventional example.

(8b) is the frame, and the scream is the thermal head (11 arrow B
This is the spring of the preload means that provides a displacement in the direction.

7L/-mu (8b). 1! : The spring wire installed between the thermal head (1) and the thermal head (1) presses the thermal head (1) in the direction of arrow B. Also, there is a gap between the shaft (4) and the collar (6), and a gap between the collar (6) and the positioning metal fitting (6).
) and the gap (a) in the assembly configuration is the gap between this spring αQ
The thermal head (1) is pushed to the right in the figure by the pressing force, and the positioning bracket (6) disappears.
The inner surface (6b) of the collar (6) and the shaft (4), that is, the platen opening-ra axis, are in contact with each other without any gap.

In other words, the pressing force of the spring is applied to the thermal head (1) by the collar (5)'' on the shaft (4) of the platen roller (8).
lr: Acts directly through the heat generating part (2) and the platen a-
Positioning with La (8) is being performed.

Structured as above! ．． The following describes the operation of the thermal head.

When the platen roller (8) is rotated in the direction of arrow A by a drive source (not shown), the thermal head (1) is pressed in the direction of arrow 0 by the spring (γ), so that there is a gap between it and the platen roller (8). The inserted recording paper (9) is indicated by arrow B.
driven in the direction. At this time, since a preload is applied to the spring α■ in the direction of the arrow H on the thermal head (1), as mentioned above, the inner surface of the positioning metal fitting (6) (
6b) comes into contact with the platen roller shaft without any gap. Therefore, even if intermittent recording operations are performed, there will be no pulsating axis misalignment due to play between the heat generation IIs (2) of the thermal head (1) and the platen roller (8). (By keeping the relative position of 81 constant, sacred place recording images with good image quality can be obtained.

In the above embodiment, the thermal head (1
) was given a preload in the direction of arrow B, but using a spring (7a) as shown in Fig. 2, the thermal head (1) t-
Even if a preload is applied from an oblique direction (direction of arrow H), the preload is generated in the direction of arrow B by component force I, so the same effect as in the above embodiment is achieved.

Further, in the above embodiment, the spring (7) which is the preload means is used.
a) Although the explanation has been given using an example in which αO acts as a compression spring, it may also act as a tension spring, or the second
Although an example in which the spring is provided in the quadrant has been shown, the same effect as in the above embodiment can be obtained even if the spring is provided in the first quadrant and acts as a tension b spring or a compression spring.

〔Effect of the invention〕

As described above, since the thermal head according to the present invention is configured such that the positioning means is brought into contact with the platen roller shaft by the preload means, good recording image quality can be obtained.

[Brief explanation of drawings]

Fig. 1 {A} to (/8) is a schematic sectional view of a thermal head according to an embodiment of the present invention, Fig. 2 is a schematic sectional view of another embodiment according to the present invention, and Fig. 3 [A] to eN are schematic cross-sectional views of a thermal head according to an embodiment of the present invention. This is a schematic cross-sectional view. In the figure, (1) is the thermal head, (2) is the heat generating part, (8) is the platen roller, (6) is the positioning metal fitting, (
6a). (6b) is the inner surface, (7), (7a),
CLOI is a spring. In the figures, the same symbols indicate the same or corresponding parts. Agent Masuo Oiwa Figure 1 (A) 6; I fill and δξ Bi! ! A W: Sekikan 2nd figure 7Q: Bamine

Claims (1)

[Claims] a platen roller that comes into contact with the heat generating part and scans the recording paper;
A thermal head having the heat generating section and positioning means for aligning the axis of the platen roller, characterized in that the positioning means is brought into contact with the platen roller axis by a preload means attached to the thermal head. thermal head.