JPH0115390B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a stain prevention device for an ink coating type printer that compensates print density based on temperature changes.

Generally, in ink coating type printers,
Bimetal is sometimes used in the anti-smudge mask that is placed in contact with the outer periphery of the type drum in order to compensate for the density of printing due to temperature.

That is, the non-uniformity of printer print density is a factor that directly affects printer devices, and various research and development efforts have been made to find ways to compensate for the darkness of print. It is known that this problem can be easily solved by linking bimetals that act based on temperature changes.

However, when a bimetal is attached to a printer mechanism, structurally complicated parts are required, the printer cannot be constructed compactly, and the cost of the printer itself increases, making it difficult to form the printer at a low cost.

The present invention was made in view of the above problems, and
By locking a mask positioning member made of a material with a linear expansion coefficient different from that of the frame to the stain prevention mask that is pivoted on the frame, the stain prevention mask is indirectly oscillated in response to temperature changes to compensate for the darkness of the print. The purpose of the present invention is to provide a dirt prevention device for a printer that cleans the printer.

A preferred embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows the main parts of a print stain prevention device for an ink coating type printer, and in the figure, reference numeral 1 denotes a frame made of a metal material. A type drum 2 is arranged above the frame 1 so as to roll with an ink roll 3 coated with ink.

Paper 4 is arranged in front of the type drum 2, and the paper 4 is pressed against desired type rings 2a, 2b, 2c, and 2d by a plurality of stamping hammers 5 arranged in a row.

In the above-mentioned printing mechanism, a stain prevention device is formed by easily attaching the stain prevention mask 6 and the mask positioning member 7 to the limited space between the paper and the type drum.

That is, the stain prevention mask 6 has an approximately comb-like stain prevention part 6a whose tip can be positioned in the groove provided between the type rings 2a, 2b, 2c, and 2d of the type drum 2, and whose lower part is folded. It has a plate shape with a bent portion 6b.

The lower end of this bent portion 6b is rotatably supported by a support portion 1a that partially protrudes from the frame 1. Further, above the bent portion 6b, the frame 1
The other end of a mask positioning member 7 made of, for example, a plastic material with a large coefficient of linear expansion, which is different from the material of the frame 1 to which one end is fixed, is locked via a pin 8.

Therefore, the anti-fouling mask 6 is positioned on the frame 1 so as to be able to swing around the support portion 1a as a fulcrum depending on temperature changes.

That is, when the temperature rises, for example, the mask positioning member 7, which is larger than the expansion coefficient of the metal frame 1, expands and operates so that the stain prevention part 6a of the stain prevention mask 6 is separated from the type drum 2, thereby preventing the ink roll 3 from moving from the type drum 2. Prevents an increase in the amount of ink applied and controls the density of printing. Further, when the temperature decreases, the mask positioning member 7 contracts and the stain prevention portion 6a of the stain prevention mask 6 approaches the type drum 2 again.

and the type rings 2a, 2b of the type drum 2,
It acts as if ink is constantly applied to 2c and 2d.

Next, another embodiment of the present invention will be described with reference to FIG.

FIG. 2 is a side view of the main part of the dirt prevention device of the printer, and shows the support part 1 in which the metal frame 11 is bent.
The upper end of the folded portion 16b of the stain prevention mask 16 is pivotally supported by 1a.

The mask positioning member 7 made of plastic material has one end secured to the metal frame 11 and the other end secured to the lower end of the bent portion 16b via a pin 8.

The distance L between the locking points between the support portion 11a and the pin 8 of the mask positioning member 17 can be set arbitrarily, but the degree of increase in width by which the tip stain prevention portion 16a of the stain prevention mask 16 moves changes depending on the size of this distance L. It will expand and be displaced.

In this way, in this embodiment, the dirt prevention mask 16
The stain prevention device has a structure in which the fulcrum position of the metal frame 11 with respect to the mask positioning member 17 is reversed compared to the embodiment shown in FIG.

Therefore, when the density of printing is compensated for according to temperature changes, the ink density on the type drum 2 can be controlled by the swinging displacement of the stain prevention mask 16.

Also, a metal frame 11, a dirt prevention mask 16, and a mask positioning member 1 made of plastic material.
The material relationships of 7 can be reversed, and in that case, the fulcrum positions in the configurations of FIGS. 1 and 2 may be reversed.

As described above, in the present invention, a mask positioning member made of a material with a linear expansion coefficient different from that of the frame is disposed in order to oscillate and displace the stain prevention mask in accordance with temperature changes, thereby compensating for the darkness of printing. Therefore, the application effect as a dirt prevention device for printers is great.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a main part of a stain prevention device for a printer showing an embodiment of the present invention, and FIG. 2 is a partial side view showing a modification of FIG. 1. 1, 11...Metal frame, 2...Type drum, 3
...Ink roll, 6,16...Stain prevention mask, 6
a, 16a... Dirt prevention part, 6b, 16b... Bending part, 7, 17... Mask positioning member.

Claims (1)

[Claims] 1. In a printer that applies ink to type on a type drum and then hits printing paper against the type with a printing hammer, the printer includes a frame and a material that is rotatably supported by the frame and is made of a material that has a larger coefficient of linear expansion than the frame. and a type drum provided between the type drum and the printing paper, provided between the type strings at a predetermined distance from the surface of the type drum, and supported by the frame so as to be movable toward and away from the type drum. a smudge prevention mask, and a smudge prevention mask fixed to the frame and made of a material having a larger coefficient of linear expansion than the frame, the smudge prevention mask being separated from the frame support position by a distance shorter than the distance from the frame support position to the type drum. The anti-smudge mask is supported at a position where the anti-smudge mask is supported on the type drum by elongation between the point fixed to the frame and the point supporting the anti-smudge mask, and the anti-smudge mask is moved away from the type drum by contracting. A dirt prevention device for a printer, which includes a mask positioning member that brings the mask closer to the drum.