JPS6042018B2 - How to stretch the presser sheet of a contact printing machine - Google Patents

Description

[Detailed description of the invention] The purpose of the present invention is to perform close contact printing on an object to be printed.

The present invention relates to a method for tensioning a presser sheet used to bring a document into close contact with an object to be printed in a contact printing machine. Normally, a contact printing machine stacks an original such as a negative film and an object to be printed, such as a film or a photoreceptor such as a printing plate, on a transparent object such as glass, and completely prints the object. A presser sheet such as a rubber sheet or mylar sheet is stretched over the object to be printed while applying pressure, and a vacuum is drawn between the transparent object and the presser sheet by an appropriate means, and the transparent object, original and The image on the document is printed onto the object by irradiating light from one surface side of the transparent body while maintaining close contact with the object.

However, in the conventional tensioning of the presser sheet, for example, the presser sheet is wound into a roll, one end of which is fixed with a fixing device fixed on a transparent holding frame, and then the presser sheet is stretched over the object to be printed. The presser sheet was stretched over the object to be printed by rolling the rolled presser sheet.

When using this method, it is easy to tension the presser sheet, but since the outer surface of the presser sheet is stretched by winding and the inner surface of the presser sheet is contracted by winding, the tension is Depending on the configuration, the outer surface portion of the presser sheet comes into contact with the object to be printed and receives a force in the contraction direction, and the inner surface portion of the presser sheet receives a force in the elongation direction.

Therefore, if the object to be printed is closely observed as the surface portion of the presser sheet moves in the direction of contraction, individual surface portions will receive a shearing force, and as a result, the accurately set position of the object to be printed will be shifted. The problem was that complete adhesion could not be achieved due to the formation of wrinkles.

For this purpose, for example, as shown in FIG. 1, a press roll 4 is rotatably attached to an arm rod 3 rotatably provided on a roll shaft 2 of a presser sheet 1 wound into a roll. The shaft 2 of the sheet 5 is rolled in the direction of arrow A on a guide 11 installed at a constant distance from the surface of the transparent body 6, and the presser sheets 1 are successively drawn out, and the presser sheet 7 is A method has also been used in which the press roll 4 is rolled and the load W applied to the press roll 4 is applied to press the roll 4 into close contact.

Even with this method, as the rolled presser sheet 5 rolls, the outer diameter of the rolled presser sheet 5 gradually decreases, and the angle α between the pressed-out presser sheet 7 and the object to be burned gradually increases. However, as the outer diameter of the rolled presser sheet 5 becomes smaller, problems similar to those in the case where the presser sheet described above is directly stretched from the roll presser sheet 5 arise.

Furthermore, since a separate load source is required to apply a desired pressing force to the pressing roll 4, special equipment for this purpose is also required.

In FIG. 1, 9 is a hole that serves as a connection port for connecting to a vacuum pump or the like to create a vacuum between the presser sheet 7 and the transparent body 6, and 10 is a hole that connects one end of the presser sheet to the glass frame 6. It is a fixing device for fixing on the holding frame of 1.
2 shows the manuscript.

The present invention was devised to solve the above-mentioned drawbacks of the conventional example, and when the presser sheet is stretched, the shrinkage deformation caused by the deformation recovery of the wound presser sheet acts on the object to be burned. The purpose is to prevent this from happening.

In the method of the present invention, the free end side of a roll-shaped presser sheet formed by winding the presser sheet around a rotating shaft is transparently moved along a guide roll rotatably provided at the tip of an arm rod pivotally connected to the rotating shaft. It is fixed on the holding frame of the transparent body through the space between the body and the rolled presser sheet, and the rolled presser sheet presses the presser sheet below it against the transparent body side, and the rotation center of the guide roll is set at a certain level with the transparent body. The presser sheet is stretched by moving the presser sheet while maintaining the distance and rotating the roll-shaped presser sheet. The method of the present invention will be explained below using a contact printing machine to which the method of the present invention is applied. FIG. 2 is a partial sectional view of a main part of a contact printing machine according to an embodiment to which the method of the present invention is applied.

6 is a transparent body, and the original 12 and the object to be printed 8 are placed on the transparent body 6.
They are stacked on top of each other.

On the other hand, reference numeral 5 denotes a rolled presser sheet in which the presser sheet 1 is wound around a shaft 2. An arm rod 3 is rotatably attached to the shaft 2, and one end of the arm rod 3 is rotatably mounted. A guide roll 13 is provided freely, and the rotating shaft of the guide roll 13 is configured to roll and move in the direction of arrow A on the guide 11 which is installed at a constant distance from the surface of the transparent body 6.

On the other hand, the presser sheet 7 pulled out from the rolled presser sheet 5 passes between the rolled presser sheet 5 and the object to be printed 8 along the guide roll 13, and one end thereof is attached to the holding frame of the transparent body 6. It is fixed to a fixing device 10 fixed on top.
If the guide roll 13 is moved in the direction of arrow A while rolling in this state, the rolled presser seal 5 will also roll and move in the direction of arrow A as the guide roll 13 rolls, and the presser sheet 7 are extracted sequentially. This pressed-out presser sheet 7 faces the surface of the object to be printed 8 one after another along the outer periphery of the guide roll 13, and is pressed onto the object to be printed 8 by the roll-shaped presser sheet 5 and stretched one after another. Ru.

In this case, the angle β between the pushed out presser sheet 7 and the surface of the object to be printed 8 is always maintained constant regardless of the decrease in the outer diameter of the rolled presser sheet 5, and the guide 1
By reducing the distance between 1 and the surface of the transparent body 6, the angle β can be made extremely small.

Therefore, when the presser sheet 7 is stretched, the transparent body 6
is positioned substantially parallel to the surface of the sheet, and in this state is pressed by the rolled presser sheet 5.

Therefore, the deformation of the surface portion of the presser sheet 7 on the object to be printed 8 side in the shrinking direction, which was a drawback of the conventional method, is almost eliminated, and the object to be printed 8 is not displaced relative to the original 12, and the object to be printed 8 is Inconveniences such as wrinkles on the skin are completely eliminated.

When tensioning the presser sheet 7, since the weight of the rolled presser sheet 5 is quite large, the force of the rolled presser sheet 5 to press the presser sheet 7 against the surface of the transparent body 6 is applied to the rolled presser sheet. By relying on the own weight of the presser sheet 7, there is no need for a dedicated load source for pressing the presser sheet 7 against the transparent body 6 side, thereby simplifying the configuration of the device used. can.

As is clear from the above explanation, according to the method of the present invention, even if the outer diameter of the rolled presser sheet decreases as the presser sheet is stretched, the angle between the transparent body and the presser sheet remains constant during tensioning. And since this angle can be made sufficiently small, it is possible to prevent the position of the object to be printed from shifting and the occurrence of wrinkles due to shrinkage of the surface of the transparent object side of the presser sheet, and also to simplify the configuration of the apparatus to be used. There are some that exhibit excellent effects such as being able to do the following.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining a method of stretching a presser sheet in a conventional contact printing machine. FIG. 2 is a partial sectional view of the main parts of a contact printing machine to which the method of the present invention is applied. Explanation of symbols, 1 and 7...
Presser sheet, 5...Rolled presser sheet, 6.
... Transparent body, 8 ... Burning object, 12 ...
...Manuscript, 13...Guide roll.

Claims (1)

[Claims] 1. A presser sheet with one end fixed on the transparent body holding frame is stretched over the original stacked on the surface of the transparent body and the subject to be printed, and the transparent body, the original, and the subject to be printed are held in close contact with each other. In a contact printing machine that prints an image on a document onto an object by irradiating light from the back side of the transparent body, the free end side of a roll-shaped presser sheet formed by winding the presser sheet around a rotating shaft is used. is fixed on the transparent body by passing it between the transparent body and the rolled presser sheet along a guide roll rotatably provided at the tip of the arm rod pivotally connected to the rotating shaft, and fixed on the transparent body by the rolled presser sheet. Pressing the presser sheet against the transparent body side, and moving the center of rotation of the guide roll while maintaining a constant distance from the transparent body to sequentially feed the presser sheets from the rolled presser sheet while rotating the rolled presser sheet. How to stretch the presser sheet for a contact printing machine.