JPH0223353B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a thermal printer.

Conventional structure and problems thereof A conventional thermal printer is shown in FIGS. 3 and 4, and its problems will be explained. 1 is a line type thermal head, and 2 is a recording paper on which printing is performed by the thermal head. The recording paper 2 is pressed against the thermal head 1 by a cylindrical platen 3, and is conveyed in the direction of arrow A by a driving roller 9a and a driven roller 9b directly connected to a motor 4, and simultaneously printed by the thermal head 1. The platen 3 is made up of a rubber 5 and a rotating shaft 6. The rotating shaft 6 is supported at both ends by bearings 7, and the platen 3 rotates in the direction of the arrow B as the recording paper 2 moves in the direction of the arrow A. Further, the platen 3 presses the recording paper 2 in the direction of arrow C by a spring 8 so as to come into close contact with the thermal head 1.

The above is the general structure and operation of a conventional thermal printer. However, in the case of the above structure, paper feeding was delicate and there were many problems. That is, during paper feeding, the recording paper 2 moves in the direction of arrow A due to the rotation of the driving roller 9 and the driven roller 9b, but the mutual movement at this time is due to the movement of the recording paper 2 and the thermal head 1.
The relative movement between the recording paper 2 and the platen 3 is not sliding but rolling. Therefore, if the diameter of the platen 3 differs even slightly at both ends, the paper feed amount of the recording paper 2 will differ at both ends of the platen 3, causing the paper to meander in the direction of arrow D as shown in Figure 2, which will cause a major problem. Ta.

Furthermore, if there is a difference in the pressing force of the spring 8 that presses the platen 3 at both ends of the platen 3, meandering of the paper occurs for the same reason as above.

Various methods have been used to solve the above problems, but it has been extremely difficult to completely eliminate meandering of the paper.

Next, another conventional example is shown in FIGS. Here, 10 is a copying machine, 11 is a manuscript,
Inside the copying machine 10, there are a roll-shaped recording paper 2 (the starting end thereof is designated as 12), a window 13, a lens 14,
It has a one-dimensional image sensor 15, a line-shaped thermal head 1, a platen 3, and an illumination 16 that illuminates the original 11.

The above is the configuration of a conventional copying machine, and the operation method thereof will be explained next. First, the copying machine 10 is placed on the original 11 by manual operation, and when a power switch (not shown) is turned on, the circuit inside the copying machine 10 is activated. Next, the starting end 12 of the roll-shaped recording paper 2 is held and fixed on top of the original 11 by hand, and while the copying machine 10 is moved in parallel in the direction of the arrow E, the recording paper 2 is moved outside the copying machine 10 in the direction of the arrow F. Pull it out and copy it. At this time, the light from the illumination 16 illuminates the original 11, and the reflected light is imaged from the window 13 through the lens 14 onto the one-dimensional image sensor 15 and read at the same time.
Copies are made one after another by the thermal head 1, and the copied recording paper 2 exits the copying machine 10 in the direction of arrow F. Note that between the one-dimensional image sensor 15 and the thermal head 1, there is a control section 17 that processes data read by the image sensor 15 and sends it to the thermal head 1. To synchronize the feeding speeds of the original 11 and the recording paper 2, hold the starting edge 12 of the recording paper 2 against the original 11 by hand and move the copying machine 10 in parallel in the direction of arrow E. The recording paper 2 whose length is equal to the moving distance of 10 in the E direction is shown by the arrow F.
They are sent out in the same direction, allowing them to synchronize with each other. By the above operations, the characters and figures of the original document 11 are copied onto the recording paper 2.

However, in the copying machine configured as described above, paper meandering occurs for the same reason as mentioned above, which is a serious problem. Furthermore, as shown in FIG. 7, even if the copying machine 10 is operated so that the G end of the recording paper 2 is pulled strongly in an attempt to correct the meandering of the paper once it has occurred, the meandering cannot be corrected. It was impossible.

OBJECTS OF THE INVENTION An object of the present invention is to provide a thermal printer that can prevent recording paper from meandering in a line-type thermal head printer, or can easily correct meandering once it occurs.

Structure of the Invention The present invention provides a line-type thermal head printer in which the platen is shaped so that the surface facing the thermal head is a flat surface or a curved surface with a large curvature, and the recording paper slides between the thermal head and the platen. By adopting a structure in which the recording paper is fed out while moving, meandering of the recording paper is prevented.

DESCRIPTION OF EMBODIMENTS FIGS. 1 and 2 show an embodiment of the present invention. In this embodiment, all the other parts other than the platen 3 are the same as those in the conventional example, so their explanation will be omitted. In addition, since its operation and operation are the same as in the conventional example and are self-evident, we will omit the explanation.
Only the structure, movement, and operation of the parts will be explained.

As shown in FIGS. 1a and 1b, in a line-type thermal head printer, the platen 3 made of an elastic material such as rubber is shaped so that the surface of the platen facing the thermal head 1 has a large curvature. A curved surface (Fig. 1 a) or a flat surface (Fig. 1
As shown in FIG. b), the recording paper 2 is fed out while sliding between the thermal head 1 and the platen 3. With this structure, the relative motion between the recording paper 2 and the platen 3, which conventionally was rolling, can be changed to sliding, and the relative motion between the recording paper 2 and the thermal head 1 can be changed from rolling. In addition to this, the recording paper 2 can now be freely slid and fed out between the thermal head 1 and the platen 3.

As a result, even if the recording paper 2 begins to meander, as long as the roller 9 drives the recording paper 2 normally, there will be no slippage between the recording paper 2 and the platen 3 that automatically corrects the meandering of the paper. This resulted in no meandering of the paper. Also, even if there is a difference in the pressing force of the spring 8 (see Figure 3) that presses the platen 3 at both ends of the platen 3, the meandering of the paper will be automatically corrected due to slippage and will be completely eliminated for the same reason as above. Summer. Furthermore, as an accompanying effect, the diameter of the platen 3 was conventionally strictly regulated over its entire length, but in the present invention, as the platen 3 has an extremely simple shape as shown in the figure, strict dimensional regulations are no longer necessary. 3 can be manufactured at a low cost, and the shape of the platen 3 has become simpler.
Because it is small, it does not require large space,
Thermal printers can now be made smaller and lighter.

Furthermore, since the radius of curvature of the platen of the present invention is larger than the diameter of a conventional cylindrical platen, the contact area between the platen and the thermal head is large, which makes it difficult to assemble the platen. Installation precision is no longer required, making assembly easier.

Further, FIG. 2 shows a copying machine according to another embodiment of the present invention. The platen 3 portion is exactly the same as in the previous embodiment. The effect of the present invention in this embodiment is that, as shown in FIG. 6, even if the G end of the recording paper 2 is pulled strongly in an attempt to correct the meandering once it has occurred, the meandering cannot be corrected. However, according to the present invention, it is now possible to easily manually correct the meandering of the paper. That is, as explained in FIG. 6, even if the recording paper 2 starts meandering as shown in the figure, by operating the copying machine 10 so that the G end of the recording paper 2 is strongly pulled, the recording paper can be Due to the slippage between the platen 2 and the platen 3, meandering of the paper can now be easily corrected.

It should be noted that, as shown in Figure 1b,
The surface of the platen 3 facing the thermal head 1 is treated with a surface treatment 18 such as Teflon that has a low coefficient of friction in order to improve the sliding between the platen 3 and the recording paper 2.
has been applied.

Effects of the Invention The present invention has a simple configuration that can prevent meandering when feeding recording paper, and is an inexpensive and space-saving method.
It is possible to realize a thermal printer that is easy to assemble and is equipped with a platen that can manually correct the meandering of paper to feed the paper normally even if the meandering occurs.

[Brief explanation of drawings]

FIG. 1a is a plan view showing an embodiment in which the platen surface of the thermal printer of the present invention is a curved surface with a large radius of curvature, and FIG. 1b is another embodiment of the present invention in which the platen surface is flat. A cross-sectional view of the platen,
Fig. 2 is a structural sectional view of a copying machine using a platen according to an embodiment of the present invention, Fig. 3 is an external view of a conventional thermal printer, and Fig. 4 is a top view of the conventional thermal printer shown in Fig. 3. Figure 5 is a cross-sectional view of the structure of a conventional copying machine, Figure 6 is an external view of the conventional copying machine in use, and Figure 7 is a diagram showing the meandering of paper in a conventional copying machine. It is an external view. 1... Thermal head, 2... Recording paper, 3...
Platen, 10... Copy machine, 14... Lens, 1
5... Image sensor, 18... Surface treatment.

Claims (1)

[Claims] 1 A line-type thermal head, a platen provided opposite to the thermal head and having a longitudinal direction in the line direction of the thermal head, and a recording paper inserted between the thermal head and the platen. 1. A thermal printer that performs printing while manually moving the printer body relative to the printer body, wherein the platen is comprised of a non-rotating member that is pressed against the thermal head.