JPS6273962A - Thermal printer - Google Patents

Abstract

PURPOSE:To obtain a thermal printer capable of giving high-quality printing for papers of rough surface and having a small size at low cost by combining a flat platen with a head having heating element with pointed glaze portion. CONSTITUTION:A flat platen 26 made of an elastic meterial is fixed to a platen base 27. A thermal head is integrated with the upside of a head fin 22 by bonding a base plate 23 with partially projected glaze portions 25. The head is pressed on the platen 26 set oppositely through a paper 14 by a force F in the direction of an arrow. In this case, the relation between the dimension (h) of the projected glaze and the flexion delta of the platen 26 by pressing is controlled to be 0.02<=delta<=2h. The concentration of facial pressure on and near the heating elements 28 is made possible. As a result, the pressing force necessary printing for rough-surface papers can be reduced, and the cost of the printing can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a thermal transfer printer, and particularly to improving print quality on rough surface paper.

[Background of the invention]

Conventional thermal printers include those having a thermal head and a cylindrical platen disposed opposite to the thermal head, as disclosed in Japanese Utility Model Application No. 60-34447;
As in Japanese Patent No. 94373, there is a type in which the platens disposed opposite each other have a flat plate shape.

In these devices, no measures have been taken to improve the printing quality on rough paper, and even if measures have been taken, the effects have been largely insignificant.

The reason for this is that the pushing force required to increase the contact pressure between the heating element of the thermal head and the paper, which is essential for improving the quality of printing on rough paper, becomes too large.

The mechanism systems that are currently commercialized cannot produce that pushing force, and even if the mechanism system is changed, the cost will increase significantly and the size of the device will also increase.

Below, FIGS. 2 to 6 will be described in detail.

FIG. 2 shows an example in which a conventional head and a round platen are used. When the thermal head 15 is pressed against the platen 18 through the paper 14, the head 1 of the circular platen 18
When the contact area with 5 (through the paper 14) is flat and the length Ω must be greater than the total height of the characters, the amount of deflection of the flat part of the circular platen is equal to the platen diameter. Generally speaking, Oi is about 0.2 for a large diameter platen, and becomes larger for a small diameter platen. This value is about 2 to 4 times the height of the partial glaze 24 provided on the substrate 23 of the thermal head 15, 40 to 50μ, so the contact area between the head 15 and the platen through the paper (surface pressure The glaze (generating portion) is not limited to only the partial glaze 24 but also extends to the surface portion of the head substrate 23. This situation is shown in Figure 3.

The surface pressure generated on the head substrate 24 is not the surface pressure necessary for writing characters, but is the surface pressure that is generated in vain. In order to improve the printing quality on rough surface paper, it is sufficient to locally increase the surface pressure near the heating element 28 on the partial glaze 24, but in this configuration, even if the suppression is increased, the entire head substrate remains in contact. Therefore, the surface pressure increase rate around the heating element is small, and the suppression loss increases at the surface of the substrate. As a result, the pushing force required to obtain the necessary surface pressure becomes significantly large, which causes serious problems in practical use, such as an increase in the size of the device and an increase in cost.

4 is almost the same as the configuration shown in FIG. 3, in which the partial glaze on the head substrate 23 is one local protrusion glaze 25.

In this case as well, there is a practical problem for the same reason as in Figure 3 (
Since the partial glaze near the heating element 28 locally protrudes, the print quality is slightly improved).

5 and 6 show an example in which a conventional thermal head 15 and a flat platen 26 are combined.

As shown in FIG. 5, when using the flat platen 26,
Compared to the case where a circular platen 18 is used, the amount of deflection of the contact portion when the thermal head 15 is pressed against the flat platen 26 through the paper 14 can be reduced. The hardness of the flat platen 26 can be set higher than the hardness of the circular platen 18. As a result, the printing quality can be improved because the surface pressure near the heating element 28 can be increased, but it is necessary to obtain the surface pressure necessary for writing on paper whose surface smoothness is several seconds.

It still requires a considerable pushing force (2 kg in experiments), which is not at the level of commercialization.

With these conventional techniques, it has been impossible to print with high quality on rough surface paper at the commercial level.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the conventional examples and to provide a thermal printer that is small, inexpensive, and capable of printing on rough paper with high quality.

[Summary of the invention]

Simply increasing the head pushing force to increase the contact pressure between the heating element of the thermal head and the paper, which is essential for improving printing quality on rough paper, has fatal drawbacks such as making the device large and expensive. I had.

Therefore, we investigated ways to obtain surface pressure while suppressing the increase in pressing force. 1. We found that the combination of a head with a sharpened glaze on the heating element and a flat platen had the greatest effect on improving printing quality on rough surfaces. Things became clear.

[Embodiments of the invention]

Figure 1 shows an external view of the Shikudansha printer.

A shaft 1 (4) is fixed between the side plate (1) 1 and the side plate (2) 2. A carriage 5 is disposed so as to be able to slide on the shaft (1) 4. A ribbon cassette 7 and a thermal head 15 are mounted on the carriage 5, and inside the ribbon cassette 7.

An ink ribbon 16 is stored. On the carriage 5, a timing belt 10 is driven by a carriage motor 8.
In the figure, it is configured to be movable in the left and right direction.

The line feed motor 11 transmits driving force to a gear (1) 12 fastened to the shaft of the platen 18 to feed the paper 14.

Paper can also be fed in the same way by turning the platen knob 13 by hand. By moving the release lever 20 in the front-back direction, the paper pressing roller 7, which is slidably arranged on the shaft 3, can be pressed against or released from the paper surface. 6 is a home position sensor; 9 is the thermal head】5
This is a flat cable for energizing equipment, etc. For convenience of explanation, this printer uses a unidirectional printing method in which printing is performed only when the carriage 5 moves in the right direction, and the ink ribbon 16 is wound up only when it moves in the printing direction.

Also, line feed motor 1]-, carriage motor 8
．． The home position sensor 6, thermal head 15, etc. are controlled by a controller 21.

A flat platen 26, an embodiment of which will be described below with reference to FIG. 7, is an elastic body and is fixed to a platen base 27. Further, in the thermal head, a substrate 23 having a locally protruding glaze 25 is integrated onto the head fin 22 by bonding or other means.

This head is connected to a flat platen 2 placed opposite to this head.
6 shows the state in which the paper 14 is pressed in the direction of the arrow with force F.

At this time, the dimensions of the local protrusion gray h (height from the surface of the substrate 23) and the deflection δ of the flat platen 26 due to head pressure
By setting the relationship of approximately 0.02≦δ<2h, it is possible to concentrate the surface pressure near the 1 heating element 28 (this is clear from the fact that the surface pressure can be expressed as pressing force ÷ contact area). be). As a result, it becomes possible to reduce the pushing force required for printing on rough surface paper, making it possible to downsize the device 9 and reduce costs (if a conventional circular platen 18 is used).

The relationship between δ and h is δ>2h to 4h, and the head substrate 2
This basically solves the drawback of large surface pressure loss on the 3rd floor. ).

In the range of h<δ<2h, the surface of the head substrate 23 also comes into contact with the flat platen 26 via M, 14, resulting in a slight loss of surface pressure; however, the hardness of the flat platen 26,
By devising the plate thickness, structure, etc., the loss of surface pressure on the surface of the substrate 23 can be suppressed to a range that does not cause any practical problems (for example, a platen with low hardness and a platen thickness of 1 stroke or less, or a platen with a hardness of 6
Possible methods include using a hard platen of 0" or more, or integrating platens with a two-layer structure with different rubber hardness)
.

As mentioned above, the technical points to obtain the maximum effect in improving the printing quality on rough paper are to sharpen the partial glaze to increase the surface pressure of the heating element 28, and to effectively use the head pressing force to generate heat. This is a combination of a flat platen 26 for concentrating on the element 28 portion.

FIGS. 8 and 9 are cross-sectional views in the printing direction of partial glazes (sharpened glazes) in claims 2 to 4.

W is the total width of the glaze and h is the total height of the glaze.

r is the radius of curvature, and d is the width of the heating element.

These figures are all examples of application of the locally protruding glaze 25 for the purpose of concentrating surface pressure on the heating element 28 and making the heating element 28 penetrate into the recess of the paper 14.

〔Effect of the invention〕

According to the present invention, it is possible to print on rough paper with high quality while being small and inexpensive.

[Brief explanation of drawings]

Fig. 1 is an external view of a thermal transfer printer, Fig. 2 is an external view of a head touch part showing a conventional example (1), and Fig. 3 is a sectional view of main parts of a head touch part showing a conventional example (1). , FIG. 4 is a sectional view (2) of main parts of a head touch section showing a conventional example, and FIG. 5 is an external view (2) of a head touch section showing a conventional example.
FIG. 6 is a sectional view of main parts of a head touch part showing a conventional example;
FIG. 7 is a sectional view of a main part of a head touch part showing the present invention;
FIG. 8 is a sectional view (1) of a local protrusion glaze showing the present invention.
, FIG. 9 is a cross-sectional view of a local protrusion glaze (2) showing the present invention.
). 1...Side plate (1), 2...Side plate (2), 3...Shaft (1), 4...Shaft (2), 5...Carriage, 6
... Home position sensor, 7... Ribbon cassette, 8... Carriage motor, 9... Flat cable, 1o... Timing belt, 11... Line feed motor, 12... Gear (1) , 13...Platen knob,]4...Paper, 15...Thermal head,
16... Ink ribbon, 17... Paper pressing roller,
18...Platen, 19...Paper guide, 20...
Release lever, 21... Controller, 22... Head fin, 23... Board, 24... Partial glaze, 2
5... Local protrusion glaze, 26... Flat platen, 27... Platen base, 28... Heat generating element.

Claims (1)

[Claims] 1. A thermal printer having a thermal head and a platen disposed opposite to the thermal head, wherein a partial glaze layer having a plurality of heating elements is provided on a substrate of the thermal head, The shape of the partial glaze layer is columnar in the direction perpendicular to the printing direction, and the cross-sectional shape in the printing direction is formed to have two or more steps of protrusions, and a heating element is disposed at least at the top of the protrusions. A thermal printer characterized in that a thermal head and a platen disposed opposite to the thermal head have a generally flat shape at least in a portion facing a row of thermal heating elements, and are constructed by combining the thermal head and the platen. . 2. In the product described in claim 1, the shape of the partial glaze having the heating element of the thermal head has a ratio w/h of the total width w to the height h of the partial glaze layer of approximately 15.
Thermal printer made below. 3. In the item described in claim 1, the total width dimension of the partial glaze having the heat generating element of the thermal head is 1 to 4 times the projected width of the heat generating element, or approximately 450 mm.
Thermal printer below μm. 4. The thermal printer according to claim 1, wherein the partial glaze having the heating element of the thermal head has a cross-sectional shape in the printing direction of approximately triangular or approximately trapezoidal. 5. A thermal printer according to claim 1, in which the relationship between the total height h of the locally protruding glaze and the amount of deflection of the platen due to head pressing force is 0.02<δ<2h.