JPH06166191A - Attaching tructure of thermal head - Google Patents

Abstract

PURPOSE:To prevent occurrence of warp and torsion with extension due to thermal expansion by attaching an end of a long thermal head in the longitudinal direction to a support member fixedly and attaching other end to the support member slidably along the longitudinal direction of the thermal head. CONSTITUTION:A line thermal head 1 is attached to a blanket 6 as a support member having almost the same length as the head 1. The blanket 6, which makes both ends of the head 1 in the longitudinal direction rock up and down, is attached to a liftable pressing frame through pins. One end of the head 1 in the longitudinal direction is fixed and attached to the blanket 6 with screws 3 passing through holes 6b at one end of the blanket 6 in the longitudinal direction. By stepped screws 10 passing through slotted holes 6c at other end of the blanket 6, other end of the head 1. is attached to the blanket 6 slidably in the direction of longitudinal axis. For engagement of the slotted holes 6c and axes 10a of the stepped screws 10, dimension without looseness is made, and the length of the axis 10a is made to be over the thickness of the blanket 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting structure for a long thermal head.

[0002]

2. Description of the Related Art A line thermal head, which is a long thermal head used in a line printer or the like, is usually used while being attached to a support member. The one shown in FIG. 7 is an example, and the line thermal head 1 is fixed to the bracket 2 serving as a supporting member at both ends and the central portion of the line thermal head 1 in the longitudinal direction by fixing with screws 3.

[0003]

When the line thermal head 1 is fixed to the bracket 2 with the screw 3 or the like and thus mounted, when the line thermal head 1 is overheated, the bracket 2 and the line thermal head 1 are connected to each other. Due to the difference in expansion and contraction due to thermal expansion, warping and twisting occur like bimetal. FIG. 8 shows the warpage of the combination of the iron bracket 2 and the aluminum line thermal head 1. Further, even if the line thermal head 1 and the bracket 2 are made of the same material, warping or twisting may be caused slightly due to the difference in shape.

As a result, the contact pressure of the platen roller (not shown) of the line thermal head 1 is not uniform and uneven printing occurs, and if an ink ribbon is used, wrinkles of the ink ribbon will occur. .

Further, in recent years, the line thermal head 1 cannot be sufficiently cooled due to the demand for downsizing, although the heat generation amount of the line thermal head 1 is increasing due to the speeding up of the printer. However, the amount of deformation such as warpage and bending described above cannot be ignored.

Further, the same problem occurs when used in an extremely low temperature or high temperature atmosphere. According to an experiment by the applicant, the contact pressure of the line thermal head 1 on the platen roller deviates from the design value by about 25% in the high temperature atmosphere of 50 degrees and the low temperature atmosphere of -5 degrees due to the above-mentioned warp and deflection. The part was confirmed.

[0007]

One end of a long thermal head in the longitudinal direction is fixedly attached to a support member, and the other end of the thermal head in the longitudinal direction is attached to the support member. It was attached so that it could slide along the direction.

[0008]

The difference in expansion and contraction between the long thermal head and the supporting member due to temperature change can be absorbed by the portion where the thermal head is slidably attached to the supporting member along the longitudinal direction of the thermal head.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. The same parts as those shown in the conventional example are designated by the same reference numerals. The print head unit 4 of the printer according to the present embodiment has a structure in which a line thermal head 1, which is a long thermal head, is pressed and held so as to be contactable and separable on a platen roller 5 rotatably attached to a fixed frame (not shown). Has become.

The line thermal head 1 is attached to a bracket 6 which is a support member having substantially the same length as the line thermal head 1. The both ends of the line thermal head 1 in the longitudinal direction are vertically swingable, and the bracket 6 is attached to a vertically movable pressing frame 7 via pins 8. Further, at both ends of the bracket 6 in the longitudinal direction, a guide portion which engages with the rotating shaft 5a of the platen roller 5 to perform relative positioning between the longitudinal direction of the line thermal head 1 and the axial direction of the platen roller 5. 6a is formed. The pressing frame 7 has both ends 7 at the swing ends 9a of a pair of left and right swing frames 9 attached to a fixed frame (not shown).
a is supported.

Here, a method of attaching the line thermal head 1 to the bracket 6 will be described in detail. First,
A hole 6b is formed at one end of the bracket 6 in the longitudinal direction, and an elongated hole 6c is formed at the other end along the longitudinal direction of the line thermal head 1. Then, one end of the line thermal head 1 in the longitudinal direction is fixedly attached to the bracket 6 by the screw 3 passing through the hole 6b, and the other end of the line thermal head 1 is fixed by the stepped screw 10 passing through the elongated hole 6c. Is attached to the bracket 6 slidably in the longitudinal direction of the line thermal head 1.
Further, the fitting between the elongated hole 6c and the shaft portion 10a of the stepped screw 10 is dimensioned so that there is no rattling. Further, the length of the shaft portion 10a is equal to or larger than the plate thickness of the bracket 6, and the line thermal head 1 and the bracket 6 are brought into close contact with each other by the spring force of the spring washer 11.

In such a structure, there is a difference in expansion and contraction due to thermal expansion between the bracket 2 and the line thermal head 1 when the temperature of the line thermal head 1 rises due to heat generation and when used in an extremely low temperature or high temperature atmosphere. Even so,
Since the difference is absorbed by the portion where the line thermal head 1 is slidably attached to the bracket 6 along the longitudinal direction of the line thermal head 1, the line thermal head is not warped or twisted.

Next, a second embodiment of the present invention will be described with reference to FIGS. The same parts as those shown in the above-mentioned embodiment are designated by the same reference numerals and the description thereof will be omitted. In the present embodiment, the adjustment plate 13 fixedly mounted on the bracket 6 with the screw 12 is attached to the adjustment plate 13 and the elongated hole 6c of the embodiment.
The long hole 13a is formed instead of the long hole 13a.
The lower bracket 6 is provided with a fool hole 6d.
The line thermal head 1 is slidably attached to the bracket 6 along the longitudinal direction of the line thermal head 1 via the adjusting plate 13 by the stepped screw 14 passing through the elongated hole 13a. Also, the long hole 1
The fitting of 3a and the shaft portion 14a of the stepped screw 14 is dimensioned so that there is no rattling. Further, the shaft portion 14a
Is longer than the thickness of the bracket 6 and the adjusting plate 13, and the line thermal head 1 and the bracket 6 are brought into close contact with each other by the spring force of the spring washer 11.

In such a structure, the longitudinal direction of the line thermal head 1 and the axial direction of the platen roller 5, which are relatively positioned by fitting the guide portion 6a of the bracket 6 to the shaft 5a of the platen roller 5, Fine adjustment can be performed by loosening the screw 12 and adjusting the attachment position of the adjusting plate 13 to the bracket 6.

[0015]

EFFECTS OF THE INVENTION One longitudinal end of a long thermal head is fixedly attached to a supporting member, and the other longitudinal end of the thermal head is fixed to the supporting member along the longitudinal direction of the thermal head. Since it is slidably attached, the difference in expansion and contraction between the thermal head and the support member due to temperature changes can be absorbed by the portion where the thermal head is slidably attached to the support member along the longitudinal direction of the line thermal head. Therefore, it is possible to prevent warping, twisting or the like of a bimetal from occurring due to a difference in expansion and contraction due to thermal expansion between the support member and the thermal head, and it is possible to stably obtain good print quality. It will be possible.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a first embodiment of the present invention.

FIG. 2 is an exploded perspective view showing a print head unit.

FIG. 3 is a vertical sectional side view.

FIG. 4 is a vertical cross-sectional view taken along the longitudinal direction of the line thermal head, showing a slidable mounting portion taken out.

FIG. 5 is an exploded perspective view showing a second embodiment of the present invention.

FIG. 6 is a vertical cross-sectional view taken along the longitudinal direction of the line thermal head, showing a slidable mounting portion taken out.

FIG. 7 is an exploded perspective view showing a conventional example.

FIG. 8 is an explanatory diagram showing warpage due to temperature change.

[Explanation of symbols]

 1 Thermal head 6 Support member

Claims (1)

[Claims] 1. A longitudinal thermal head having a longitudinal end fixedly attached to a support member, and the thermal head longitudinal other end fixed to the support member along the longitudinal direction of the thermal head. Thermal head mounting structure characterized by being slidably mounted.