JPS6011377A - Platen - Google Patents

Abstract

PURPOSE:To perform high quality printing while preventing the generation of a broken character by constituting the titled platen of rubber with elastic hardness of 16-60 deg. so as to bring the surface in its printing front surface side into flat contact with a thermal head by slight pressing in a printing direction. CONSTITUTION:During printing, a thermal head 6 is brought into contact with a platen 20 under pressure vertically in a diameter direction to the center of said platen 20 around its center, that is, the center of thermal elements 7a-7g. The surface of said head 6 at the pressure contact part is elastically deformed to a flat surface shape by this pressure contact force and the thermal head 6 is uniformly contacted with the platen 20 through printing paper 9 without forming a gap therebetween. Therefore, a broken character is not generated during printing. In this case, because the surface 20a of the platen 20 is a curved surface near to a flat surface, the dimension of elastic deformation for obtaining a flat surface is made smaller than a conventional dimension and pressure conact force is also made small. In addition, because a space S is present, the platen 20 is easy to elastically deform.

Description

TECHNICAL FIELD The present invention relates to a platen, and more particularly to a platen made of rubber and used in a Therma/L/' printer for serial printing.

There are two types of conventional platens of the type described in Prior Art 5: those whose front surface for printing is formed into a long rectangular bar shape and those whose surface is formed into an elongated cylinder shape. The main structure and operation of a thermal printer using a conventional platen will be explained, and the drawbacks of a conventional platen will be explained.

First, the main structure of a thermal printer using a bar-shaped platen in the form of an elongated rectangle will be explained with reference to FIGS. 1 to 3Q.

In Fig. 1, the platen indicated by the symbol l is made of rubber with a rubber elastic hardness of 40 degrees to 60 degrees, and the surface 1a on the front side of printing is formed in the shape of a thick rectangle elongated in the direction of the printing digit. The surface 1a is formed into a uniform plane.

This platen 1 is fixed on a platen boulder 2 which is its support.

Further, the reference numeral 3 denotes a carriage shaft, which has an irregular cross section and is horizontally suspended parallel to the platen 1 so as to be freely rotatable. A carriage 4 is slidably attached to the carriage shaft 3, and the printing front facing the carriage 4 platen is printed on the flexible print 4K 5.
The connected thermal head 6 is fixed.

As shown in FIG. 2, on the front surface of the thermal head 6 on the platen side, there are, for example, seven heat sensitive elements 7a to 7g along the right edge.
The heat-sensitive elements 7a to 7 are arranged in a row, and each heat-sensitive element 7a to 7
g is a flexible print) and is connected to each signal line of the board 5.

On the other hand, wires 8 are stretched on both sides of the carriage 4 and are stretched by a drive means (not shown).

In the configuration described below, the thermal head 6 presses the printing paper 9 against the surface 1aJ- of the platen 1 during printing.
At this time, the front surfaces of the thermal head 6 and the carriage 4 are inclined with respect to the horizontal direction of the platen 1 so that only the heat-sensitive elements 7a to 7g of the thermal head 6 and their vicinity are pressed against each other.

During printing, the carriage shaft 3 moves in the direction of arrow C in FIG.
The carriage 4 rotates in the direction of the arrow B, and in an ideal state, the thermal head 5 passes through the printing paper 9 and forms a gap on the surface of the platen 1, as shown in FIG. The printing paper 9 is assumed to be thermal paper whose heated part develops color when heated.
After that, the CPU drives a driving means (not shown).
By pulling the wire 8, the carriage 4 is moved in the direction of arrow C in FIG.

At the same time, electric signals are selectively applied to the heating elements 7a to 7g+ to generate heat according to the pattern of a character generator (not shown);
The printing paper 9 is colored and printed in a dot pattern.

That is, as shown in FIG. 3(b), while moving in the direction of arrow C, at times tl, t2.13, t4, the heat-sensitive elements 7a to 7g are sequentially 7g, 7f, 7@.

By selectively applying signals such as 7d, . . . to generate heat, dots are printed corresponding to the positions of the heat-sensitive elements 7a to 7g at each time t1 to t1,
The characters rAJ are printed in a 1” dot pattern.

However, in the above configuration, when the thermal head 6 is pressed into contact with the platen l through the printing paper 9, as shown in FIG.
It is very difficult to bring the surface 1a+ into uniform pressure contact without any gaps. Tori Uno ζ,).

Latin 1 has a relatively high gum elastic hardness (and is formed with a rubber band), and the surface 1a is flat.

The surface 1a is flat, the surface 1a is flat, the G is evenly distributed, the G is pressed evenly, and the G is pressed against the thermal head 6. Accuracy can be lost due to vibrations and shocks over time.

For the following reasons, if the thermal head 6 does not come into uniform pressure contact with the parts other than the platen, a so-called character chipping occurs, where the printing part is chipped.

For example, if there is a gap at the top of the thermal head 6 during pressure welding as shown in Figure 3(c) + Q, then Figure 3(d)
4. The upper force of the printed character "A" is missing as shown here. Also, Figure 3(e)? If there is a gap at the bottom as shown here, the third
As shown in Figure (f), the lower part of the printed character "A-" is missing.

Also, as shown in FIG. 3(g).

In the case where Latin 1 is twisted and the gap at the top becomes larger as it goes to the right side G, in this case, as shown in Figure 3 (1) is greatly lacking.

Next, the configuration and operation of a conventional thermal printer using a cylindrical platen are shown in Figures 4 (a) to (C).
Explain according to the following. 1k or the same as the conventional one except for the platen.

The platen designated by numeral 10 has a rubber elastic hardness of 25 degrees to 40 degrees.
It is formed into a cylindrical shape from high-grade rubber, that is, rubber whose comb elastic hardness is lower than that of the conventional example described above, and the cores on both sides are supported by a rotatable platen shaft IN. In this case, the platen 10 serves not only as a printing stand but also as a paper feed roller that feeds the printing paper 9 in the printing line direction.

During printing, as shown in FIG. 4(b), the thermal head 6' is pressed perpendicularly in the radial direction of the platen O with its center, that is, the center of the heat-sensitive elements 7a to 7g, as the center. In this case, since the platen 10 is made of flexible rubber, the symbol F1 is shown in FIG. 4(C).
〜F3 The surface of the pressure welded part becomes dimensional due to the pressure welding force.
□ When the heat-sensitive elements 7a to 7g are crushed, the width of the opposing portion becomes flat, and the heat-sensitive elements 7a to 7g are pressed against the platen 1° without any gaps.

With this configuration G, the heat-sensitive elements 7a to 7g are pressed against the platen IO without any gaps, so that occurrence of missing characters can be prevented.

However, this configuration requires a relatively strong pressing force F1-F3 to flatten the portion of the width CH, and the pressing force Fl
"If F3 is strong, the platen 10 of the thermal head 6
The frictional force against the As a result, the torque for driving the carriage 4 increases, leading to an increase in power consumption of the thermal printer. Also, the pressing force F at the center of the thermal head 6.

is large, and the pressure contact forces Fl and F3 at the upper and lower parts become smaller, and the pressure contact forces differ depending on the part, so
The transition temperature of the heat generating part differs depending on the part, resulting in a difference in the density of the print.

Furthermore, if the radius R1 of the platen 10 is increased to make the width CH portion nearly flat in order to weaken the above-mentioned pressing force, the platen IO becomes large, leading to an increase in the size of the printer.

Furthermore, it is difficult to form a uniform round platen with high accuracy from rubber having low rubber elastic hardness.

The present invention was made in order to eliminate the drawbacks of the conventional printers as described above, and is used in a thermal printer that performs serial printing.It is used in a rubber platen, and is inexpensive and has a simple configuration. The purpose is to provide a printer that is smaller and consumes less power, prevents missing characters, and enables high-quality printing even when there is some deviation in the precision and assembly of the printer's component parts. It is said that

EXAMPLE The present invention will be described in detail based on Example G shown in FIGS. 5(a) to 5(C). In the figure, the same parts as in FIGS. 1 and 4 are given the same reference numerals, and the explanation thereof will be omitted. In other words, the structure of the parts other than the platen 20 and the platen 21 is the same as the conventional one, so the explanation thereof will be omitted. .

The platen designated by reference numeral 20 in FIG. 5(a) is
It is made of rubber with a low rubber elastic hardness of 15 to 60 degrees, has a fan-shaped cross section, and has a surface 20a on the front side of printing.
11 Long substantially rectangular, rod-shaped surface 2
0. A is a curved surface curved in an arc shape in the vertical direction in the figure, that is, in the printing line direction*, and has a radius of curvature indicated by the symbol R2 in FIG. 5(b). This radius of curvature is set to about 8 mm to 100 mm depending on the purpose of the thermal printer.

Further, the platen boulder 21 indicated by the reference numeral 21 is formed into a prismatic shape* from a material such as a highly rigid metal, and has a deep long groove 21a with a rectangular cross section on the front side of the print, and has a substantially U-shaped cross section. There is.

The platen 20 is fitted and fixed into the long groove 21a of the platen boulder 21 with the front surface 20a facing the printing surface. In this case, the cross section of the long groove 21a is rectangular, whereas the cross section of the platen 20 is fan-shaped, so a space Q is defined between the wall surface of the long groove 21a and the side surface of the platen 20, which is indicated by the symbol S. .

According to the above configuration, the radius of curvature R2 can be set large without increasing the thickness and height of the platen 20, and the surface 1a can be made into a curved surface close to a flat surface.

During printing, the thermal head 6 is activated as shown in Fig. 5(C).
is pressed perpendicularly to the radial direction of the center G of the platen 20 with its center, that is, the center of the heat-sensitive elements 7a to 7g, as the center. Due to this pressing force Q, the surface of the pressed portion is elastically deformed into a planar shape, and the thermal head 6 is pressed uniformly to the platen through the printing paper 9 without any gaps, so that no missing characters occur during printing.

Further, in this case, since the surface 20a is a curved surface close to a flat surface as described above, the dimension J of elastic deformation required to make the surface 20a flat is
2 is the dimension of the conventional example mentioned above -! Since it can be smaller than 1,
The pressing force can also be small.

Furthermore, since there are spaces S on both sides of the platen 20 for releasing elastic deformation, the platen 20 easily deforms elastically. Therefore, the pressure contact force described in "-" can be smaller.

Since the pressure contact force is small as described above, the difference in pressure contact force due to the difference in the position of the pressure contact portion is small, and therefore, a large difference in shading does not occur within the -printed characters.

In addition, since the pressure contact force is small, the sliding friction of the thermal head 6 against the platen 20 (print paper 9) is small.
Carriage 4! ! A small torque is required for the ilA movement. Furthermore, the shape of the platen 20 itself is easier to form than the conventional cylindrical shape.

Although the cross-sectional shape is fan-shaped in the embodiment, it is of course not limited to this, and may be, for example, approximately rectangular, approximately trapezoidal, or other shapes. In short, any shape may be used as long as it has a cross-sectional area smaller than that of a cylinder having the same curvature as the printing surface.

As is clear from the explanation of ``Effects'', the present invention is used in a thermal printer that performs serial printing, and the platen made of rubber has a rubber elastic hardness of 15 degrees or more and 6 degrees.
The cross-sectional area of a cylindrical body made of rubber with a diameter of 0 degrees or less, whose front surface is curved in the printing line direction with a radius of 8 mm to 1,100 mm, and whose cross-sectional area is the same as curvature in item 3. Since it has a small configuration, it is inexpensive and simple, and even if there is some deviation in the accuracy of the printer's component parts and assembly accuracy, it prevents the occurrence of missing characters and prints with high quality. be able to. Furthermore, the platen itself can be configured to be small, making it possible to downsize the printer as a whole and further reduce the power consumption of the printer.

[Brief explanation of the drawing]

Figure 1 is a perspective view of the main parts of a conventional thermal printer using a platen, Figure 2 is a front view of the thermal head, and Figure 3 (
a), (c), (e), and (g) are respectively side views showing the pressure contact state of the thermal head during printing with the thermal printer in Fig. 1, and Fig. 3 (b), (d), and (f). , (h
) is an explanatory diagram showing the printing state in each pressure contact state, FIG. 4(a) is a perspective view of the main parts of another conventional platen-based thermal printer, and FIG. 4(b) is a side view of No. 47a). , FIG. 4(C) is an explanatory view showing the pressure contact state during printing by the platen of FIG. 4(a), FIG. 5(a) is a perspective view of the main part of the thermal printer using the platen of the present invention,
FIGS. 5(b) and 5(c) are side views respectively illustrating the configuration of the peripheral portion of the platen in FIG. 5(a) and the pressure contact state during printing.

Claims (1)

[Claims] Thermal printer Q is used to perform serial printing by driving a thermal head that is in pressure contact with the printing paper.The platen is made of rubber and has a rubber elastic hardness of 15 degrees or more and 60 degrees or less. is in planar contact with the thermal head with slight pressure in the printing line direction, is curved in an arc shape with a large curvature that does not affect the running of the thermal head, and has a cross-sectional area of a cylindrical body having the above-mentioned curvature. A platen characterized by being formed smaller than the .