JPS602932A - Presser for thermal copying machine - Google Patents

Abstract

PURPOSE:To prevent a white omission with relatively small pressure by superposing an air-permeable flexible body on an elastic body and pressing an original and a heat-sensitive sheet against each other in contact. CONSTITUTION:The heat-sensitive sheet 7 formed by sticking a thermoplastic synthetic resin film and an ink penetration type porous base together and the original 5 where ink 6 sticks are superposed upon stage glass 6. Then, rear paper 4 as a reinforcing body for the heat-sensitive sheet 7, wool felt 3 which is 1mm. thick, and mono-cellular synthetic rubber sponge 2 are stacked thereupon, and pressure is between the glass stage 8 and a rigid plate 1 until the synthetic rubber sponge 2 becomes 6.5mm. thick; and they are irradiated with a flash from below the stage 8 to obtain a stencil for mimeograph printing, which is carried out. Thus, almost no white omission is eliminated at the black condensation part of the original. Further, the 25% compressive load of the sponge is 351- 630g/cm<2>.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a suppressor for bringing a document and a thermal sheet into close contact with each other in a thermal copying machine.

BACKGROUND OF THE INVENTION Conventionally, flash-type thermal copying apparatuses have been known that can quickly reproduce original images, such as printed matter, handwritten materials, drawings, etc., onto a heat-sensitive sheet by heating and burning.

In this type of heat-sensitive copying apparatus, the original and the heat-sensitive sheet are pressed into close contact with each other by the elasticity of an elastic body such as a sponge in order to improve the heat transfer between the original and the heat-sensitive sheet. Further, as the above-mentioned elastic body such as a sponge, a relatively hard single-cell sponge or a relatively soft open-cell urethane foam is used, and the surface thereof is covered with a thin cloth or an air-impermeable sheet.

The thermal copying apparatus constructed in this manner has a drawback in that it is difficult to copy well the dense black portions of the original image. In particular, when performing stencil printing using a stencil printing base paper made by laminating a thermoplastic synthetic resin film and an ink-permeable porous support as a heat-sensitive sheet, stripes of white ink appear in areas corresponding to dense black areas of the document. Transparent areas may occur and the original may not be reproduced faithfully. The above-mentioned white ink-transparent areas are usually referred to as white spots, but in order to completely eliminate these spots, extremely strong pressure is required, and it is an expensive device for producing wide copies.9 Not practical.

The present invention has been made to solve these difficulties.
According to the present invention, a breathable flexible body is superimposed on a relatively hard elastic body that applies pressurizing force, and this brings the document and the heat-sensitive sheet into close contact with each other under pressure, thereby causing white spots with a relatively small pressure. You can prevent this from happening.

It is presumed that the cause of the white spots is that gas is generated from the heat-sensitive sheet at locations corresponding to densely black areas of the document, causing the document and the heat-sensitive sheet to be separated. However, when the pressing body according to the present invention is used, the gas generated in this way passes through the document and the backing paper for reinforcing the heat-sensitive sheet and is absorbed by the breathable flexible body, so it is thought that no white spots will occur. When only a relatively hard single-cell elastic body is used as a suppressor, the single-cell elastic body does not have air permeability, so it does not absorb the gas and white spots occur.

When only relatively soft open-cell urethane foam is used as the pressing member, the pressing member must be compressed to an extremely thin state in order to obtain the necessary pressing force. It is difficult to achieve this as a whole because of the deformation of the stage glass, etc. used to perform flash irradiation.

Next, embodiments according to the present invention will be described with reference to the drawings.

Example 1 A thermosensitive sheet 7 made of a thermoplastic synthetic resin film and an ink-permeable porous support laminated on a stage glass 8 is overlaid with an original 5 on which ink 6 has been adhered to the paper, and then The backing paper 4 as a reinforcing body of the heat-sensitive sheet 7
m + g wool felt 3 and 8 m thick single-cell synthetic rubber sponge 2 are stacked and pressure is applied between the glass stage 8 and the rigid plate 1 until the thickness of the single-cell synthetic rubber sponge 2 becomes 6.5 mm, and the glass stage When a stencil printing base paper was prepared by irradiating flash light from below 8 and stencil printing was performed, almost no white spots occurred in the densely black areas of the manuscript.

In addition, the 25 inch compression load of the above single cell synthetic rubber sponge is 351
It is 117 cm2 to 63097 cm2.

Example 2 The wool felt 3 in Example 1 was replaced with soft open-cell urethane foam (thickness in uncompressed state: 8 tm), and stencil printing was performed with other conditions being the same. Almost no white spots occurred.

Example 3 When the wool felt 3 in Example 1 was replaced with a synthetic fiber cloth with a thickness of 0.5 rtm, and other conditions were kept the same, stencil printing was performed, and there were almost no white spots in the densely black areas of the original. It didn't happen.

Although this is not an example of the present invention, except for the wool felt 3 in Example 1, the single-cell synthetic rubber sponge 2 and the backing paper 3 were in direct contact with each other, and the other conditions were the same as in Example 1. When 1iiiIJ was performed, large white spots occurred in densely black areas of the original.

This fact proves that the present invention is effective.

[Brief explanation of drawings]

The drawings are cross-sectional views showing embodiments of the present invention. Patent applicant: Sanwa Co., Ltd. Fuji Kiden Co., Ltd.

Claims (1)

[Claims] A thermal copy made by stacking an elastic body that can be compressed to apply sufficient pressure and a breathable flexible body with a thickness of 0.5 mm or more so that the breathable flexible body is located on the side of the heat-sensitive sheet. Mechanical suppressor.