JPS6031965A - Preventive method of reverse printing of sheet printer printing on both surface - Google Patents

Abstract

PURPOSE:To detect printing paper, the facing direction thereof differs, to each other, automatically by printing data while Indian ink is detected by a detector on the printing of the back and automatically stopping the operation of a printer when the detector does not detect Indian ink. CONSTITUTION:Printing paper 11a, to the surfaces printing is completed and which is turned back and stacked on a paper-feed section 5, is fed to a first printing section 1 by a conveyor 7 on a feed-board 6 one by one. When printing paper 11a is turned over normally at that time, Indian ink 13 and a detector 12 face each other, and a machine is normally operated continuously. However, when printing paper 11a turned back by mistake intends to pass on the feed- board 6, the detector 12 is operated because the detetor 12 cannot detect Indian ink 13, and a paper feed is stopped temporarily. Accordingly, a supply to the first printing section 1 of printing paper 11a, the direction thereof differs to each other, can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 shows a schematic configuration of a conventional sheet-fed printing press (an example of color printing). In the figure, the printing paper 7 stacked in the paper feed section S is conveyed onto the feed board 6 by a conveyor 7.
The paper is fed into the printing section l, and the seventh color is printed while passing through the engagement part between the blanket cylinder g and the impression cylinder 9, and then the printing paper after 0 passes between the impression cylinder 9 and the intermediate cylinder 10. Follow the route of 1st, 3rd and 3rd printing department, 3. While passing through 'I, the first color is printed and becomes printing paper //a, which is stacked with the printed side facing up in paper output section B.

When printing on the back side of the printing paper //a that has been printed on the front side, when returning the same printing paper //a to the paper feed fffr3, manually or mechanically turn the appropriate number of sheets so that the back side is facing up. After being reloaded as shown, the paper is carried into the paper feed section 3, and the back side is printed using the same procedure as the front side printing.

It is normal to turn this printing paper //a (Fig. 3) over as shown in Fig. 9, but if you accidentally turn it over and stack it in the paper feed section S as shown in Fig. S, the back side will be printed. The problem was that the printing was reversed and a large amount of paper was wasted in a short period of time.

Conventionally, printing paper has to be manually turned over by an appropriate number of sheets at a time, so it is difficult to avoid turning the paper in the wrong direction from time to time. However, even if sheets of paper with different orientations are mixed in a stack of printing paper, the present invention can automatically detect and handle these before printing. The purpose is to provide a method of prevention.

In order to achieve this object, the present invention prints ink on a predetermined part of the paper along with a pattern when printing on the front side, and performs printing while detecting the ink with a detector when printing on the back side. This invention is characterized by automatically stopping the operation of the printing press when there is no paper, and relates to a method for preventing reverse printing without the risk of producing waste paper.

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 3 and 3 show embodiments of the present invention.

FIG. 2 is an enlarged view of a portion corresponding to section ``■'' in FIG. 1.

In FIG. 1, l is the seventh printing section, S is the paper feeding section, O is the feed board, 7 is the conveyor, Aa is the frame, /l is the printing paper, and these are the same as in FIG. Further, / is a detector, which is attached to the frame Aa of the feed board B at a position where it can detect ink /3 (printed at the same time as the pattern /ll when printing on the surface) as shown in FIG. 3 near the illustration. It should be noted that the detector 7.2 is a well-known one, and a description of its groove structure will be omitted here.

Next, to explain the operation, after going through the same process as explained in connection with FIG. 1, the front surface printing is completed as shown in FIG. The sheets /a are fed one by one onto the feed board A by the conveyor 7 to the first printing section /a. At this time, as shown in FIG. 1, if the printing paper //a is turned over normally, the ink /3 and the detector /J face each other, and the machine continues to operate normally. However, as shown in Figure 3, when the printing paper //a that has been turned over by mistake tries to pass over the feed board, the detector /A cannot detect the ink 13, so the detector /A
is activated and paper feeding is temporarily stopped. Therefore, it is possible to prevent printing paper //a with a different orientation from being supplied to the first printing section/.

Since the present invention is constructed as described above, if the reverse printing prevention method of the present invention is implemented in a printing press, the occurrence of paper waste due to reverse printing as seen in the past can be completely prevented. .

[Brief explanation of the drawing]

Fig. 7 is a side sectional view of a conventional sheet-fed printing press, Fig. 1 is an enlarged side sectional view of the part corresponding to section ■ in Fig. 1 of the apparatus for carrying out the method of the present invention, and Fig. 3 is a surface printed FIG. 4 is a perspective view of the paper that has been correctly turned over, and FIG. S is a perspective view of the same paper that has been turned over incorrectly. Explanation of the main parts of the diagram C... 1st printing section 3... Paper feeding section 6... Feed board //a... Printing paper 12...
...Detector 13...Sumi/4 (...Picture)

Claims (1)

[Claims] When printing on the surface, ink is printed on designated areas of the paper along with the pattern,
A sheet-fed sheet for double-sided printing, characterized in that printing is performed while detecting the ink with a detector when printing on the back side, and when the detector does not detect the ink, the operation of the printing press is automatically stopped. How to prevent reverse printing on printing presses.