JPH05220989A - Support structure of thermal head - Google Patents

Abstract

PURPOSE:To provide the title support structure having a simple structure and requiring no high accuracy in the positioning of respective parts themselves and the mutual positioning between the parts. CONSTITUTION:A platen roller 1 is supported by mounting the bearings 14 provided to both ends of the platen roller on the bearing holders 13 positioned on the deep side of the slit 12 formed to a chasis 10. A thermal head 20 is integrally positioned along with the platen roller by connecting the positioning plates 21 provided to both ends of the thermal head to the bearings. The free end 22a of the leaf spring 22 fixed to the rear surface of the thermal head 20 is inserted in the stopper part 24 formed to the main body of a facsimile device at a predetermined position to be engaged therewith. By this constitution, respective parts are almost linearly arranged and a structure is simplified and the thermal head is energized toward the platen by the elastic force of the leaf spring and the movement of the thermal head is suppressed by the engagement of the leaf spring.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head support structure for a thermal recording printing apparatus.

[0002]

2. Description of the Related Art A heat-sensitive printing apparatus having a thermal head is used, for example, in a facsimile machine or various printers. An example of the configuration is shown in FIG. That is, a substantially L-shaped support plate 2 is fixed to both ends of an elongated rectangular thermal head 1 in which a heating element required for a print digit for one line is provided in a lateral example. The support plate 2 is swingably pivotally attached to a support shaft 3 fixed to the facsimile main body via a bearing 2a provided on the base end side below the support plate 2. Further, the forked portions 2b provided at the upper end of the support plate 2 are contacted and connected to both ends of the rotary shaft 5 of the platen roller 4 of the thermal head 1 which is disposed opposite to each other.

Further, the thermal head 1 is constantly urged toward the platen roller 4 side by a spring 6 arranged on the back side thereof. And the thermal head 1
The belt-shaped recording paper 8 continuously drawn from the roll recording paper 7 passes between the platen roller 4 and the platen roller 4. At the time of this passage, the recording paper 8 is printed by being heated by the thermal head 1 while receiving an appropriate holding pressure between the thermal head 1 and the platen roller 4 by the urging force of the spring 6.

Then, the forked portion 2b and the rotary shaft 5 described above.
The thermal head 1 and the platen roller 4 are positioned by coupling with the recording head 8 and the recording paper 8 is moved (rotation of the platen roller 4) by mounting the bearings 2a and the forked portions 2b on the shafts 3 and 5, respectively. Accordingly, the force applied to the thermal head 1 in the direction of arrow A is suppressed.

[0005]

However, in the above-mentioned conventional support structure, the bearing portions 2a and the forked portions provided at both ends of the support plate 2 for suppressing the rotation of the thermal head 1 (direction of arrow A). 2b are attached and fixed to the support shaft 3 and the rotary shaft 5 attached to the facsimile main body, respectively. Therefore, the size and shape of the support plate 2 and
High accuracy is required for positioning between the parts 2, 3 and 5,
In addition, the complicated structure not only hinders miniaturization, but also has various problems of increasing cost.

The present invention has been made in view of the above background, and its object is to have a simple structure, which does not require high precision in positioning each component itself and each other, and an assembling work. It is to provide a support structure for a thermal head that is easy and inexpensive.

[0007]

In order to achieve the above object, in a thermal head supporting structure according to the present invention, a platen roller directly or indirectly supported by an apparatus main body and a platen roller disposed opposite to the platen roller. The thermal head is connected to the platen roller by abutting positioning members formed at both ends of the thermal head. Then, one end of a leaf spring having a predetermined width is fixed to the back side of the thermal head, and the other end of the leaf spring is engaged with a stopper means provided in the apparatus body. Further, the stopper means has a portion that comes into contact with the side surface in the moving direction of the leaf spring, which follows the movement of the thermal head caused by the rotation of the platen roller.

[0008]

The platen roller and the thermal head are connected through the positioning member so that the positioning between them can be performed. Further, due to the elastic force of the leaf spring, the thermal head is brought into contact with the platen roller with an appropriate pressure. When the recording paper passes between the thermal head and the platen roller, the thermal head heats the recording paper at the time of the passage to perform a predetermined printing on the recording paper. At this time, the platen roller rotates and the recording paper moves, and along with this, the thermal head also tries to move and rotate by being urged in the moving direction of the recording paper. Then, the leaf spring integrated with the thermal head also follows the leaf spring and tries to move in a predetermined direction. However, since the stopper means is located in the moving direction, the movement of the leaf spring and thus the thermal head is restricted.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a thermal head support structure according to the present invention will be described in detail below with reference to the accompanying drawings. As shown in FIGS. 1 and 2, a platen roller 11 having an elongated cylindrical shape and an outer peripheral surface made of a rubber material is rotatably and pivotally attached to a chassis 10 which constitutes a part of a frame of a facsimile apparatus main body. Specifically, first, the slits 12, 12 are formed at predetermined positions on both side surfaces of the chassis 10, and a circular bearing holding portion 13 wider than the slit 12 is formed on the inner side of the slit 12. A small cylindrical bearing 14 is attached to the rotary shafts 11a at both ends of the platen roller 11.
Is rotatably inserted and arranged in a loosely fitted state.

The diameter of the tip end side portion of the bearing tool 14 is substantially equal to the diameter of the bearing holding portion 13, and the tip end side portion of the bearing holder 14 is formed by cutting both sides in the radial direction in parallel. Cut portion 14a and second cut portion 14b
Is provided. Then, the width t1 of the first cut portion 14a and the width t2 of the second cut portion 14b have a relationship of t1 <t2, and further, the width t1 of the first cut portion 14a.
Is slightly narrower than the width t3 of the slit 12.
As a result, when the first cut portion 14a and the slit 12 are positioned orthogonally to each other as shown in FIG. 1, the slit 1 is larger than the diameter of the bearing 14 (the diameter of the bearing holding portion 13) R1.
Since the width t3 of 2 is small, the bearing 14 is locked by the bearing holder 13 and the detachment of the platen roller 11 is suppressed.

On the other hand, an elongated substantially rectangular thermal head 20 capable of printing at least one line is arranged so as to face the platen roller 11, but in the present invention,
Bifurcated positioning plates 21 and 21 extending downward are attached to both side surfaces of the thermal head 20, and leaf springs 22 and 22 having a predetermined width are provided on the back surface side of the thermal head 20.
I am wearing. Further, in this example, the positioning plate 21 and the plate spring 22 are integrally formed of a single metal plate by pressing or the like, and are fixed to the thermal head 20 with the screw 23. The bifurcated internal width of the positioning plate 21 is substantially equal to the width of the second cut portion 14b of the bearing 14, and the thermal head 20 causes the platen roller to move by aligning the two 21 and 14b with each other. 11 will be positioned.

Further, a stopper portion 24 having a shallow bottom concave shape is formed at a predetermined position of the facsimile apparatus main body facing the free end 22a side of the leaf spring 22, and the stopper portion 24 is formed.
The free end 22a of the leaf spring 22 is inserted and arranged therein. Then, due to the engagement of the two 22a, 23 and the torsional rigidity and the surface rigidity of the plate spring 22, the platen roller 1
The thermal head 20 generated by the rotation of No. 1 suppresses the rotation in the arrow B direction in the drawing.

In the structure for supporting the thermal head 20 having the above-mentioned structure, the thermal head 20 is held in a semi-floating manner by the leaf spring 22 and the rubber on the surface of the platen roller 11, so that the thermal head 20 and the platen roller 11 are held.
Factors that upset the balance of the close contact of are extremely reduced. Further, the thermal head 20 is connected to the platen roller 11 via the positioning plate 21, but is only brought into contact with the main body of the facsimile apparatus via the spring elastic force of the plate spring 22. , The platen roller 11, the thermal head 20, the leaf spring 22, and the stopper portion 23 are arranged in a substantially straight line, and the arrangement direction and the expansion and contraction direction of the leaf spring 22 are the same, and each component has a manufacturing dimension. Even if an error or the like occurs, it is absorbed by the expansion and contraction of the leaf spring 22, so that dimensional accuracy is not so required. Further, since the respective parts can be arranged in a straight line as described above, the size can be reduced.

Next, the procedure for assembling the apparatus of the above-described embodiment will be described. First, as shown in FIG. 3, bearings 14 are loaded on the rotary shafts 11a at both ends of the platen roller 11, respectively, and the bearings 14 are loaded. With the first cut portion 14a of the above and the slit 12 provided in the chassis 10 parallel to each other, the bearing 14 (the first cut portion 14a) is inserted into the slit 12 as indicated by an arrow in the drawing, As shown by the chain double-dashed line (only the tip of the bearing 14 is shown for convenience), the bearing 12 is moved to the bearing holding portion 13 on the inner side of the slit 12.

Next, as shown in FIG. 4, the platen roller 11 is arranged at a predetermined position (at this time, the first cut portion 14a of the bearing 14 is kept in the same direction (parallel) with the slit 12). Then, as shown in the drawing, the integrated thermal head 20, positioning plate 21 and plate spring 22 are made to face the platen roller 11 with the positioning plate 21 facing forward and moved in the direction of the arrow in the figure.

Then, as shown in FIG. 5, the positioning plate 21
The bifurcated tip of the second cut portion 14b of the bearing 14 is
The thermal head 20 and the platen roller 11
And are integrated in contact. Then, when the thermal head 20 is rotated in the direction of the arrow in the figure, the integrated bearing 14 (platen roller 11) also rotates accordingly.
Then, when it is rotated by approximately 90 degrees, the leaf spring 22 is inserted and fixed in the stopper portion 24 as shown in FIG. 1, and the bearing 14 is also rotated as described above, so that the first cut portion 14a is also rotated by 90 degrees. Then, as shown in FIG. 1, the slit 12 is positioned orthogonally. As a result, the platen roller 11 and the thermal head 20 are integrated so as not to be separated. When the leaf spring 22 is inserted into the stopper portion 24, the tip portion 22a of the leaf spring 22 is urged toward the thermal head 20 and crushed in order to facilitate the insertion work.

In this way, the mounting can be easily carried out by almost one-touch type, and after mounting, the disengagement is suppressed by the engagement between the bearing 14 and the slit 12 and the engagement between the leaf spring 22 and the stopper portion 24. It

It should be noted that the mounting position and the number of mounted leaf springs are not limited to the above-described embodiment. For example, in the above-mentioned embodiment, the thermal head is fixed at both ends and the free end is located at the center side. Various modifications can be made, such as the opposite arrangement (the free ends are located on both ends).

Further, the positioning plate and the leaf spring may not be integrally formed as in the above-mentioned embodiment but may be constituted by separate parts. In addition, a pair of positioning plates provided at both ends of the thermal head are integrally formed, that is,
For example, both ends of a plate having a U-shaped cross section may be used as positioning plates, and the thermal head may be fixed to the intermediate portion.

Further, the leaf spring and the stopper portion are engaged with each other at the outer peripheral surface of the leaf spring as in the above-mentioned embodiment. For example, a through hole is provided at a predetermined position on the free end side of the leaf spring. May be provided, and a projection (which serves as stopper means) to be inserted into the through hole may be provided at a predetermined position of the facsimile main body.

Further, the field of application of the present invention is not limited to the above-mentioned facsimile machine using the heat-sensitive recording paper made of roll paper, but may be a so-called cut paper type, and the paper itself is ordinary. It is also possible to use a sheet of paper and pass the paper and the heat-transferable heat-sensitive sheet between the platen roller and the thermal head. Furthermore, it is not limited to facsimile machines,
It can be applied to various printers and other devices.

The apparatus main body supporting the platen roller as referred to in the present invention is specifically the portion where the platen roller is supported is limited to the portion constituting the outer box of the mounting apparatus such as a facsimile machine. Instead, various chassis and mounting fittings located inside may be used, and in short, it may be mounted directly or indirectly to a fixed system portion with respect to the apparatus main body. Similarly, the apparatus main body provided with the stopper portion (means) is not limited to the outer box and may be a fixed system portion, and the portion where the platen roller is supported and the portion where the stopper portion is provided are not necessarily the same. It does not need to be composed of the member.

[0023]

As described above, in the support structure for the thermal head according to the present invention, the leaf spring is used to obtain a predetermined contact pressure between the platen roller and the thermal head, and the leaf spring is engaged with the stopper portion. The rigidity of the leaf spring can regulate the movement of the thermal head. Therefore, since the thermal head is only fixed on the platen roller side and is held in a semi-floating manner by the leaf spring, the structure is simple and high precision is not required for positioning each component itself and each component. As a result, the assembling work is easy and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view of essential parts showing a preferred embodiment of a thermal head support structure according to the present invention.

FIG. 2 is an exploded perspective view showing a preferred embodiment of a thermal head support structure according to the present invention.

FIG. 3 is a process drawing for explaining an assembly operation.

FIG. 4 is a process chart for explaining an assembly operation.

FIG. 5 is a process chart for explaining an assembly operation.

FIG. 6 is a diagram showing an example of a conventional thermal head support structure.

[Explanation of symbols]

 10 chassis (apparatus main body) 11 platen roller 20 thermal head 21 positioning plate 22 leaf spring 24 stopper part

Claims (1)

[Claims] 1. A platen roller directly or indirectly supported by an apparatus main body, and thermal heads arranged to face the platen roller, and positioning members formed at both ends of the thermal head are attached to the platen roller. The leaf spring having a predetermined width is fixed to the back surface side of the thermal head, and the other end of the leaf spring is engaged with the stopper means provided in the apparatus main body. The support structure for the thermal head, which has a portion that comes into contact with a predetermined portion of the leaf spring so as to prevent the movement of the leaf spring that follows the movement of the thermal head caused by the rotation of the platen roller.