JPH0361573A - Method and apparatus for measuring position of blanket and transparent printing table - Google Patents

Abstract

PURPOSE:To determine the position of a blanket with accuracy equal to or less than printing accuracy by mounting a light emitting element and a photodetector at the lower part of a printing table having a transparent substrate and measuring the position of the blanket on the basis of the detection signal of the photodetector. CONSTITUTION:A printing apparatus roughly consists of a printing table 11, a plate 12, a blanket 13, a doctor 14, a light emitting element 15 and a photodetector 16, and a transparent part 31 having a width of 10mm is provided only to the contact part of the printing table 11 in a slit form by inserting glass in a window-like state over the entire width of an object 12 to be printed. The light emitting element 15 and the photodetector 16 are provided under the transparent part 31 and the transparent object 2 to be printed is placed on the transparent part 31 and the light emitting element 15 and the photodetector 16 are constituted of an He-Ne laser oscillator and a CCD image sensor. As a result, both elements 15, 16 can be used in the position control of the blanket in printing operation and, by adjusting the position or contact pressure of the blanket by utilizing the data of both elements, printing accuracy and quality, inspection efficiency and operating efficiency can be enhanced and the number of inspectors can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a printing machine and a printing method for transferring ink to a printing material via a blanket such as a gravure plate or a planographic plate.

In particular, the present invention relates to a blanket position measuring method and apparatus for accurately grasping the blanket position, and a transparent printing table.

(Prior Art) Conventional printing method in which ink is transferred to a printing material through a blanket such as gravure or lithography is known.

In this case, the position of the blanket was not generally known.

However, as printing accuracy has improved, it has become possible to achieve skin grafts with a displacement of several tens of microns or less.

In that case, the following problems have occurred.

First, it is assumed that ink is already on the blanket. In order for the ink to transfer from the blanket to the printing material, the blanket and the printing material must come into contact.

However, if the degree of contact is too large, the cylindrical blanket will be distorted. Then, due to the distortion,
Printing accuracy decreases. Therefore, the most ideal situation is for the blanket and the printing material to be in line contact.

In this case, it is necessary to measure the degree of contact by some means. However, as a conventional means for measuring the position of a blanket, there is only the following method.

Light is emitted from the side of the printing part of the printing press. The light is then received by a sensor such as an image sensor on the side facing the light. Based on this light reception signal, the presence or absence of shielding or the width of the transmitted light is determined. And it was measured accordingly.

(Problems to be Solved by the Invention) However, the method of measuring the J3 over-type as described in the joint meeting had a drawback. This means that there will be a measurement error in millimeters in the measured values.

There are many reasons for this. Typical examples include the ability of the sensor itself, errors due to diffraction, reflection from the printing material, and the degree of smoothness of the printing material. Therefore, this method does not provide a method for measuring the position of the blanket that is compatible with printing accuracy. For the above reasons, it has not been used for position control during printing.

Therefore, there has been a need for a method and apparatus for measuring the position of a blanket, as well as a transparent printing table, for determining the position of the blanket with an accuracy that is less than the printing accuracy used for controlling the position of the blanket in actual printing.

(Means for Solving the Problems) In view of the two problems, measurement is performed using reflection measurement from the front of the blanket instead of transmission sensing from the side.

Specifically, the printing table on which the transparent printing material is placed is a transparent substrate, and the lower part of the printing table is equipped with a light emitting element and a light receiving element, and the blanket is controlled based on the light reception signal of the light receiving element. This method employs a blanket position measurement method that is characterized by measuring the position. Note that the light receiving element may be a line sensor or an area sensor, each of which has its own advantages.

In addition, as a specific method for measuring the position of the blanket,
Even if the distance between the blanket and the printing material is measured using interference, it is not a method that measures the actual time it takes for the light emitted from the light emitting element to reflect off the blanket and enter the light receiving element. Good too. However, since each has different advantages, it is not possible to make a selection based on a single condition.

Also, you can choose from a variety of devices to use. For example, in a blanket position measuring device, the printing table on which a transparent printing material is placed is a transparent substrate, and the lower part of the printing table is equipped with a light-emitting element and a light-receiving element, and similarly, the light-receiving element is a line sensor. In some cases, it is an area sensor.

Further, the structure of the printing table used therein is such that the printing table on which the transparent printing material is placed is a transparent substrate.

In addition, as an application, the printing table on which the transparent printing material is placed is a transparent substrate, and the lower part of the printing table is equipped with a light emitting element and a light receiving element, and the blanket is activated based on the light reception signal of the light receiving element. There is also a method of directly measuring the degree of distortion of the blanket by measuring the position and the contact area between the blanket and the printing material. In this case, the contact area between the blanket and the printing substrate is referred to as the nip width.

In actual printing, it is often used as a substitute value for adjusting the reliability of ink transfer. Typical width is 0.6
It is said to be mm. Therefore, it is also useful when adjusting to this value.

In addition, if the strength of the printing bed is required and the printing bed cannot be made transparent, instead of the above method, one end of the optical fiber is attached to the part of the printing bed on which the transparent printing material is placed where the blanket is to be contacted. The other end of the optical fiber is equipped with a light emitting element and a light receiving element, and a means for measuring the position of the blanket is taken based on the light reception signal of the light receiving element. The measuring device at that time is characterized in that one end of an optical fiber is provided at the portion of the printing table on which the transparent printing material is placed that is scheduled to come into contact with the blanket, and the other end of the optical fiber is provided with a light emitting element and a light receiving element. This is a blanket position measuring device.

(Function) By employing each of the above-mentioned means, measurement errors are reduced and it becomes possible to use them for position control in actual printing, thereby making it possible to improve the printing negligibility.

(Example) An example of the present invention will be described in detail using the drawings. 1st
The figure is a sectional view of a printing state showing an embodiment of the present invention. FIG. 2 is a plan view of the printing table.

The printing apparatus shown in this embodiment is roughly composed of a printing table (11
), plate (12>, blanket (13), doctor (14), light emitting element (15), and light receiving element (16)
It consists of and.

In actual printing, the printing material (2) is placed on the printing table (11).

Of these, the printing table (11) is provided with a transparent portion (31) having a width of 101 mm at the contact portion, which is fitted in a slit-like window-like manner with glass over the entire width of the printing medium.

Further, under the transparent part (31), there is a light emitting element (15).
) and a light receiving element (16).

A transparent printing material (2) is placed on the transparent portion (31) of the printing table (11).

Moreover, the light emitting element (15) and the light receiving element (16) are He-
It consists of a Ne laser oscillator and a CCD image sensor.

The other plate (12), blanket (13), and doctor (14) are the same as those of a conventionally known intaglio offset printing machine, so their description will be omitted.

(Effects of the Invention) The present invention can be used to control the position of the blanket in actual printing, and enables a wide range of real-time measurements, including not only line contact but also nip width adjustment, ink transfer status, etc.

Therefore, by using these data, it has become possible to adjust the blanket position or contact pressure in real time. This has resulted in improvements in printing accuracy and quality, improvements in inspection efficiency, improved operating efficiency, and reduction in the number of inspection personnel.

[Brief explanation of drawings]

FIG. 1 is a cross-section of a printed state showing an embodiment of the present invention.
FIG. 2 is a plan view of the printing table of the printing machine. 11 Printing table 12 plate 13 Blanket 14 Doctor 15 Light emitting element 16 Light receiving element 2) Printed material 31 Transparent part

Claims (12)

[Claims] (1) The printing table on which the transparent printing material is placed is a transparent substrate, and the lower part of the printing table is equipped with a light emitting element and a light receiving element, and the position of the blanket is determined based on the light reception signal of the light receiving element. A blanket position measuring method characterized by measuring. (2) The blanket position measuring method according to claim 1, wherein the light receiving element is a line sensor. (3) The blanket position measuring method according to claim 1, wherein the light receiving element is an area sensor. (4) The blanket position measuring method according to claim 1, wherein the distance between the blanket and the printing medium is measured using interference. (5) The blanket position measuring method according to claim 1, wherein the distance to the blanket is measured by measuring the actual time it takes for the light emitted from the light emitting element to be reflected by the blanket and enter the light receiving element. (6) A blanket position measuring device characterized in that a printing table on which a transparent printing material is placed is a transparent substrate, and a light emitting element and a light receiving element are provided at a lower part of the printing table. (7) The blanket position measuring method according to claim 1, wherein the light receiving element is a line sensor. (8) The blanket position measuring method according to claim 1, wherein the light receiving element is an area sensor. (9) A printing table in which the printing table on which a transparent printing material is placed is a transparent substrate. (10) The printing table on which the transparent printing material is placed is a transparent substrate, and the lower part of the printing table is equipped with a light emitting element and a light receiving element, and the position of the blanket is determined based on the light reception signal of the light receiving element. A blanket contact area measuring method characterized by measuring the contact area between a blanket and a printing material. (11) One end of an optical fiber is provided at the portion of the printing table on which the transparent printing material is placed that is scheduled to come into contact with the blanket, and the other end of the optical fiber is provided with a light emitting element and a light receiving element.
A method for measuring the position of a blanket, characterized in that the position of the blanket is measured based on a light reception signal of the light receiving element. (12) Blanket position measurement characterized in that one end of an optical fiber is provided at the portion of the printing table on which the transparent printing material is placed that is scheduled to come into contact with the blanket, and the other end of the optical fiber is provided with a light emitting element and a light receiving element. Device.