JPS6324405Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a picture area ratio measuring device for determining the picture area ratio from a printing plate for a printing press.

Generally, the amount of ink supplied to a printing press is determined by the area ratio of the image actually printed (the ratio of the area of the image area to the total area). Therefore, in order to set the ink supply amount, it is first necessary to determine the pattern area ratio that will actually be printed.

Conventionally, there are various methods for determining the picture area ratio, and among them, a method of determining the picture area ratio from the printing plate before it is installed on the plate cylinder is often used. In this method, as shown in FIG. 1, a scanning device 4 in which fluorescent lamps 2 and 3 are arranged on both sides of a plurality of photoelectric conversion elements 1 arranged in a row is used to scan a printing plate 5 before being mounted on a plate cylinder. , the reflected light from the printing plate 5 received by the photoelectric conversion element 1 is converted into an electrical signal, and the signal is processed to determine the picture area ratio of the printing plate 5. . In this case, the pattern area ratio is determined for each range in which the scanning device 4 moves a certain distance, and the opening degree of each ink key is set based on this.

By the way, in the manufacturing process of the printing plate 5, a burning process is usually performed. This burning treatment is performed to improve the printing durability of the printing plate 5, but since the heating treatment is performed at a relatively high temperature, in the case of a normal printing plate whose base material is an aluminum thin plate,
The problem is that the printing plate becomes wavy due to thermal deformation. Therefore, when trying to determine the picture area ratio from such a printing plate, as shown in FIG. Since the amount of reflected light received by the conversion element 1 changes, it becomes difficult to obtain an accurate picture area ratio.

Therefore, as a countermeasure to this problem, there is a method in which a large number of air intake holes are made on the entire surface of the table on which the printing plate 5 is mounted, and thereby the printing plate 5 is attracted to the table, and the unevenness caused by the burning process is corrected. it was thought. However, since there are various sizes of the printing plate 5, especially when the size of the printing plate 5 is small,
Since the number of intake holes communicating with the atmosphere increases, the suction force becomes weaker, and the above-mentioned corrective action disappears. Therefore, this method requires a complicated mechanism to close intake holes that are out of range according to the size of the printing plate.

An object of the present invention is to provide a printing plate pattern area ratio measuring device that can accurately determine pattern area ratios from printing plates of various sizes.

Therefore, in the present invention, in a picture area measuring device in which a scanning device is provided on a mounting base for mounting a printing plate so as to be movable along the printing plate, the printing plate mounting surface of the mounting base is a curved surface, and the curved surface is The above object is achieved by providing a biasing means for forcibly bending the printing plate along the curved surface, and using this biasing means to correct the unevenness of the printing plate caused by the burning process and bring it into close contact with the curved surface. It is.

Therefore, it will be explained more specifically.

Generally, printing plates come in various sizes (the most commonly used printing plates are 600 mm x 900 mm), but most are made from thin aluminum plates with a thickness of 0.1 mm to 0.5 mm. Therefore, it has the property of being easily elastically deformed by a slight external force.

This kind of printing plate is subjected to burning process, specifically
When heat-treated at a temperature of around 180 to 200 degrees Celsius, locally raised unevenness occurs. These irregularities are not particularly directional and occur on the entire surface or part of the printing plate, but the maximum height is several mm, usually 2 mm or less, so it is necessary to apply a slight external force (usually 30 to 40gf). )
Most of the problems can be corrected simply by adding .

The present invention attempts to apply this external force by curving the printing plate. In other words, if the printing plate mounting surface on which the printing plate is mounted is a curved surface, the printing plate will be curved along the curved surface. This alone can correct the unevenness that occurs on the printing plate to some extent, but if a means is provided to forcibly curve the printing plate along the printing plate mounting surface, in other words, the force that urges the printing plate in the tangential direction of the curved surface can be reduced. If added, unevenness can be corrected more effectively.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a perspective view showing the external appearance of the picture area measuring device of this embodiment, FIG. 4 is a longitudinal cross-sectional view thereof, and FIG. 5 is a cross-sectional view thereof. In these figures, 11 is a mounting base on which the printing plate 5 is mounted, and 31 is the mounting base 11.
This is a scanning device that is movably installed in the. The mounting table 11 is constituted by a box-shaped case 12, and its front surface, that is, the printing plate mounting surface 13, is inclined backward as it goes upward and is shaped into a concave curved shape in the horizontal direction. . The printing plate mounting surface 13 has guide rails 14 along its upper and lower edges.
15 is provided with two positioning guides 16 and 17 that are perpendicular to each other from one side to the bottom of the central part, and a biasing member for urging the printing plate 5 toward the positioning guide 16 on the other side of the central part. A force means 18 is provided. The biasing means 18 includes two guide grooves 19 formed parallel to the positioning guide 17 on the other side of the central part of the printing plate mounting surface 13;
20, and a pressing guide 21 parallel to the positioning guide 16 along both guide grooves 19, 20.
is movably provided, and a spring 22 is configured inside the box 12 to bias the pressing guide 21 toward the positioning guide 16.

Further, the scanning device 31 includes a cylindrical case 32.
A pair of clamping wheels 33 and 34 that clamp the front and rear surfaces of the guide rail 14 are provided on the upper part of the guide rail 1, and the guide rail 1 is driven by a drive device (not shown).
A drive wheel 35 that rolls on the upper surface of 4 is provided, and the guide rail 15 is provided on the lower inner surface side.
A guide wheel 36 is provided that rolls along.
Furthermore, inside the case 32, a plurality of photoelectric conversion elements 37 are arranged in columns in the center, and
On both sides thereof, linear light sources 38 and 39 such as fluorescent lamps are arranged in parallel. Here, when the printing plate 5 is irradiated with the irradiation light from the light sources 38 and 39 and the reflected light from the printing plate 5 is received by the photoelectric conversion element 37, the amount of the received reflected light is converted into an electrical signal. , are processed by a processing circuit (not shown). In other words, since the amount of light reflected from the printing plate 5 changes depending on the presence or absence of a pattern on the printing plate 5, the pattern area ratio of the printing plate 5 can be determined by processing a signal based on the amount of reflected light. In this case, each time the scanning device 31 moves a distance corresponding to the width of the ink key, the pattern area ratio for each range is determined.

Next, the operation of this embodiment will be explained. First, in order to mount the printing plate 5 on the mounting base 11, press guide 21
is moved in a direction away from the positioning guide 16 against the spring 22, and then one side and the bottom of the printing plate 5 are aligned with both positioning guides 16 and 17. Here, when the press guide 21 is urged toward the positioning guide 16 by the tensile force of the spring 22, the printing plate 5 is forcibly bent along the printing plate mounting surface 13 of the mounting base 11 due to the pressure of the pressure guide 21. be done. As a result, the printing plate 5 is forcibly bent along the printing plate mounting surface 13, and as a result, the unevenness caused by the burning process is corrected, and the printing plate 5 is held between the pressing guide 21 and the positioning guide 16. becomes.

In this state, the scanning device 31 is attached to the mounting base 11.
After optically scanning and detecting the image area and non-image area of the printing plate 5, which is moved along the guide rails 14 and 15 and mounted and held on the mounting table 11, the image area and the non-image area are optically scanned. Find the pattern area ratio. At this time, the printing plate 5 is curved in close contact with the printing plate mounting surface 13 of the mounting table 11, and the scanning device always moves in parallel at regular intervals along the curvature of the printing plate 5.
It is possible to always obtain an accurate picture area ratio.

Therefore, according to this embodiment, the printing plate mounting surface 13 of the mounting table 11 is formed into a concave curved shape toward the moving direction of the scanning device 31, and the positioning guides 16 and 17 are fixed to the printing plate mounting surface 13. At the same time, the press guide 21 is provided so as to be movable toward the positioning guide 16, and the press guide 21 is biased toward the positioning guide 16 by the spring 22, so that the printing plate 5 can be positioned in the positioning guides 16 and 17. After that, the spring 22 presses the pressing guide 2.
1 toward the positioning guide 16, the printing plate 5 is bent by the urging force of the spring 22 into a state in close contact with the printing plate mounting surface 13, and as a result, the unevenness caused by the burning process is removed. is corrected. Therefore, when moving the scanning device 31 along the printing plate 5 held in this state and determining the image area ratio of the printing plate 5, an accurate value can be obtained since the unevenness of the printing plate 5 has been corrected. can be obtained.

In particular, in the case of this embodiment, since the printing plate 5 is held between the positioning guide 16 and the pressing guide 21, the printing plate 5 of any size can be held on the printing plate mounting surface 13.
Since the printing plates 5 can be held in close contact with each other along these lines, the image area ratios of the printing plates 5 can be determined accurately, and the printing plates 5 can be easily loaded and removed. Moreover, since the printing plate mounting surface 13 has a concave curved shape, the printing plate 5 can be held securely.

In practice, the printing plate mounting surface 13 may have a convex curved shape, and the direction of curvature is not limited to the horizontal direction, that is, the moving direction of the scanning device 31, but may be in the vertical direction. However, when the direction of curvature is the vertical direction, it is necessary to curve the photoelectric conversion element 37 and the light sources 38 and 39 of the scanning device 31 along the direction of curvature.

As described above, according to the present invention, printing plates of various sizes can be mounted, and the unevenness caused by the burning process is corrected in the mounted state, so the image area ratio can be accurately determined for printing plates of various sizes. It is possible to provide a picture area measurement rate device that can be obtained.

[Brief explanation of the drawing]

Figures 1 and 2 are explanatory diagrams showing a conventional pattern area ratio measuring method, Figure 3 is a perspective view showing an embodiment of the present invention, Figure 4 is a longitudinal cross-sectional view thereof, and Figure 5 is a cross-sectional view thereof. It is a front view. 11...Mounting stand, 13...Plate mounting surface, 18...
...biasing means, 31...scanning device.

Claims (1)

[Scope of Claim for Utility Model Registration] (1) A mounting table on which a printing plate is mounted, and a scanning device that is movably provided on the mounting table and optically scans the pattern of the printing plate. In the printing plate pattern area ratio measuring device for determining the pattern area ratio of the printing plate based on the detection signal from the scanning device, the printing plate mounting surface of the mounting table is a curved surface,
What is claimed is: 1. An image area ratio measuring device for a printing plate, characterized in that the mounting base is provided with biasing means for forcibly bending the printing plate along the printing plate mounting surface. (2) The device for measuring the picture area ratio of a printing plate according to claim 1, characterized in that the printing plate mounting surface of the mounting table is a concave curved surface.