JPH07111558A - Head spring for facsimile - Google Patents

Abstract

PURPOSE:To evenly press a thermal head and to secure the even print density by pressing the thermal head at four points by means of two head springs having the asymmetrical elastic forces. CONSTITUTION:A head spring 1 consists of outer and inner elastic metallic pieces 4 and 5. The piece 5 has the elastic force smaller than that of the piece 4 owing to a cut part 7. The top plates 2 are screwed and fixed into an upper chassis 10 by the screw 8 with the projection parts 6 of the head springs 1 kept in the projection holes 12 respectively. Therefore both pieces 5 are set internally opposite to each other together with the pieces 4 re set externally opposite to each other. Under such conditions, these pieces are fixed. In such a constitution, the even pressing force is secured at each part of a thermal head since the elastic force of the piece 5 is set less than the piece 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head spring for a facsimile machine, and more particularly to a head spring for a thermal recording type facsimile machine.

[0002]

2. Description of the Related Art A heat-sensitive recording type facsimile apparatus having a structure in which heat is applied to a heat-sensitive recording paper by a thermal head for printing is widely used. In such a thermal recording type facsimile apparatus, the thermal head is pressed against the thermal recording paper arranged between the platen roller and the thermal head to execute printing, but in order to improve the printing efficiency and the printing quality, the spring is used. The thermal head is pressed against the recording paper by the action.

For example, like a conventional printing mechanism 50 shown in FIG. 5, two head springs 51 having eight-shaped and left-right symmetrical elastic pieces 52, 52 are attached side by side to an upper chassis 53, and these four elastic members are attached. Piece 52,52,52,5
When the two foot ends come into contact with the lower thermal head 54, the thermal head 54 is pressed downward by the elastic force generated by expanding the angle between the elastic pieces and elastically displacing them.

[0004]

However, in such a conventional configuration, the two elastic pieces on the inner side press the central portion of the thermal head 54, while the two end portions of the thermal head 54 are respectively provided with one elastic piece. Since the outer elastic piece presses, the pressing force concentrates at two points in the central part of the thermal head and becomes larger than the pressing force at both ends, and the pressing balance between the central part and both ends collapses and presses the recording paper against the platen. As a result of partial unevenness in the force applied, the printing on the recording paper becomes non-uniform, and the problem that the printing density is not stable occurs.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and a head spring for a facsimile machine which makes the pressing force on the thermal head uniform and enables a uniform and stable print density. The purpose is to provide.

[0006]

In order to achieve the above-mentioned object, a facsimile head spring according to the present invention comprises:
In a facsimile head spring having inner and outer elastic pieces that hang down on the left and right of a top plate in an eight-shape, the elastic force of the inner elastic piece is made weaker than that of the outer elastic piece, and the inner and outer elastic pieces of the spring top are formed. It is characterized in that a protruding portion facing upward is provided on either one side.

[0007]

[Function] Two head springs having an asymmetrical elastic force, which are composed of an inner elastic piece having a relatively weak elastic force and an outer elastic piece having a relatively strong elastic force, and the inner elastic pieces face each other inwardly. As described above, the thermal heads are assembled side by side so as to be pressed at four points, whereby the pressing force at the central portion of the thermal head and the pressing force at both end sides are averaged, so that the entire thermal head is made uniform. Press the recording paper with pressure to achieve uniform print density.
Furthermore, when the head spring is assembled, the protrusion provided on the top plate eliminates the occurrence of incorrect mounting.

[0008]

The FA according to the present invention will now be described with reference to the accompanying drawings.
The structure and operation of the X head spring will be described. Figure 1
(A) is a perspective view of a FAX head spring according to the present invention, and (b) is a front view thereof. Figure 2
FIG. 3 is a front sectional view showing a mounting state of a FAX head spring according to the present invention, and FIG. 3 is an exploded perspective view of a FAX machine incorporating two FAX head springs according to the present invention.

FIG. 4 shows a front sectional view of a FAX machine incorporating the FAX head spring according to the present invention, and FIG.
FIG. 8 is a front view for explaining the configuration of a conventional printing mechanism.

First, the structure of the head spring according to the present invention will be described with reference to FIG. As shown in FIGS. 1 (a) and 1 (b), the head spring 1 according to the present invention is made of a material such as metal having elasticity, and has a mounting hole 3 at the center thereof.
The outer elastic piece 4 and the inner elastic piece 5 that hang down in a left-right shape on the left and right of the top plate 2 (spring top portion) on which the holes are formed, the foot ends 4A and 5A connected to the tips of these elastic pieces 4, 5 It is composed of a notch portion 7 provided at the root portion of the top plate of one piece, and an upwardly projecting portion 6 provided on the inner elastic piece side of the top plate.

Due to the cutout portion 7, the elastic force associated with the elastic displacement of the inner elastic piece 5 is smaller than the elastic force associated with the elastic displacement of the outer elastic piece 4.

Next, the mounting state and operation of the head spring will be described with reference to FIGS. Upper chassis 10 for mounting two head springs 1 and 1 side by side
Two screw holes 11 and 11 and two protrusion fitting insertion holes 12 and 12 are formed in the.

Here, the two projection fitting holes 12 and 12 are
When the two inner spring pieces are arranged inward when the two head springs 1 and 1 are mounted side by side, the protrusions 6 and 6 are inserted into the protrusion fitting insertion holes 12 and 12 respectively. Shall be installed.

As a result of arranging the projection 6 of the head spring 1 and the projection fitting hole 12 of the upper chassis 10 as described above, even if the head spring 1 is accidentally mounted in the left-right inverted state, the projection 6 is formed. Position and projection fitting hole 1
Since the two positions are different from each other, they are not fitted to each other, so that erroneous mounting can be reliably and easily eliminated.

That is, the inner elastic piece of the head spring is automatically arranged in the correct direction only by mounting the head spring 1 in the direction in which the projection 6 is fitted and inserted in the projection fitting hole 12.

In this way, the projections 6 and 6 of the head springs 1 and 1 are inserted into the projection insertion holes 12 and 12, respectively, and then the top plates 2 and 2 are attached by the mounting screws 8 and 8. It is fixed by screwing to the upper chassis 10. As a result, the inner elastic pieces 5, 5 of the head springs 1, 1 arranged side by side face each other inward, and the outer elastic pieces are fixed in the opposite outward direction.

Next, a state in which the head spring according to the present invention is incorporated in the FAX machine will be described with reference to FIGS. 3 and 4. When the thermal head 20 is brought into contact with the platen roller 21 attached to the base 18 of the FAX machine 40, the upper chassis 10 attached with the head springs 1 and 1 is attached to the base 18 from above. The two inner elastic pieces 5 and 5 and the two outer elastic pieces 4 and 4 contact the thermal head 20 and elastically displace to generate an elastic force, and press the thermal head 20 toward the platen roller 21 at four points. .

Since the elastic force of the inner elastic piece is weaker than the elastic force of the outer elastic piece as described above, there is a pressing force applied to the central portion of the thermal head 20 by the two inner elastic pieces 5 and 5. The pressing force applied to both ends of the thermal head by the outer elastic pieces 4 and 4 can be made substantially equal, so that the pressing force at each portion of the thermal head can be made uniform.

As a result, when the recording paper 23 sent out by the motor 22 is inserted between the platen roller 21 and the thermal head 20 at the time of printing, the thermal head 20
Presses the recording paper 23 uniformly with a uniform pressing force, thereby realizing uniform printing density.

In the example shown in the above figure, the protrusion is provided on the inner elastic piece side. However, it is costly to form the protrusion by diverting the cut-out portion during cutting of the notch. Because it is advantageous. Of course, on the contrary,
The protrusion may be provided on the outer elastic piece side.

Further, the notch shown in the above embodiment is only an example for weakening the elastic force of the inner elastic piece, and other methods such as forming the plate thickness partially differently may be used. Initially, various methods can be adopted.

[0022]

According to the present invention, there are two head springs having an asymmetric elastic force, each of which is composed of an inner elastic piece having a relatively weak elastic force and an outer elastic piece having a relatively strong elastic force, each inner elastic piece being an inner part. Since the thermal heads are assembled side by side so as to face each other and pressed at four points, the pressing force at the central portion of the thermal head and the pressing force at both ends are averaged, thus making the entire thermal head uniform. A uniform printing density is achieved by pressing the recording paper with the pressing force. Further, when the head spring is assembled, the protrusion provided on the top plate can restrict the occurrence of wrong direction mounting, so that the work efficiency can be improved and the defective rate can be reduced.

[Brief description of drawings]

FIG. 1A is a perspective view of an embodiment of a FAX head spring according to the present invention, and FIG. 1B is a front view.

FIG. 2 is a front sectional view showing a mounted state of a FAX head spring according to the present invention.

FIG. 3 is an exploded perspective view of a FAX machine incorporating a FAX head spring according to the present invention.

FIG. 4 is a front cross-sectional view of a FAX machine incorporating a FAX head spring according to the present invention.

FIG. 5 is an explanatory diagram of a conventional printing mechanism.

[Explanation of symbols]

 1 Head Spring 2 Top Plate (Spring Top) 3 Mounting Hole 4 Outer Elastic Piece 4A Foot End 5A Foot End 5 Inner Elastic Piece 6 Projection 7 Cutout 8 Mounting Screw 10 Upper Chassis 11 Screw Hole 12 Projection Fitting Hole 18 Base 20 Thermal head 21 Platen roller 22 Motor 23 Recording paper 40 Fax machine

Claims (1)

[Claims] 1. A head spring for a facsimile machine, comprising inner and outer elastic pieces that hang down to the left and right of a top plate in an eight shape, wherein the elastic force of the inner elastic piece is weaker than that of the outer elastic piece. A head spring for a facsimile machine, characterized in that a projection portion directed upward is provided on either one of the inner and outer elastic pieces.