JP2543362Y2 - Mark position detection device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mark position detecting device for detecting the position of a mark marked on an object such as a web.

[0002]

2. Description of the Related Art In a case where overprinting is performed by a plurality of plate cylinders, color shift occurs unless each color is printed at a predetermined position. For this reason, a mark for each color is provided on a print target (web), and printing is controlled based on the mark.

A rotary printing press will be described as an example of detecting a mark position. FIG. 2 shows the basic structure of the upset printing of an offset rotary printing press. By sequentially passing through the printing unit consisting of the cylinder 16, black, blue, red, yellow are overprinted,
A series of printing is completed. Each plate cylinder 1 in the printing unit
The circumferences of 3, 14, 15, and 16 have the same dimensions, and printing of one leaf is performed for each rotation of the plate cylinder. On the web 12 that has passed through the printing unit, there is a pattern having the plate cylinder circumference as one unit. Printed repeatedly.

When automatic register control for preventing color misregistration by adjusting the rotation of these four plate cylinders is performed, a register mark as shown in FIG. The plate cylinder prints. In other words, the black register mark is made by the black plate cylinder 13 that prints a black pattern,
For the blue register mark, the plate cylinder for printing each color, such as the blue plate cylinder 14, prints the register mark in each color.

FIG. 3A shows a state in which there is no printing error of each color and the register error is zero. The arrow indicates the traveling direction of the web 12. (B) shows the case where the red register mark is shifted to the blue side by dmm, and at this time, the red picture is also shifted to the blue side by dmm. In other words, by monitoring the relative position between the register marks, the displacement of the picture of each color can be measured.

As a device for measuring the relative position between the register marks, a reflection type optical sensor or the like is used. This reflection type optical sensor converts the intensity of scattered light from the web surface into an electric signal, and outputs a signal when the register mark of each color passes through the light spot portion of the optical element as the web 12 advances.

FIG. 4 is a diagram showing an optical system of the register mark detecting device. Reference numeral 1 denotes a light source, 2 denotes a lens for condensing light from the light source 1, 3 denotes a half mirror that transmits, reflects and condenses light, and 4 denotes an object to be measured such as a web.
Reference numeral 5 denotes a light receiving element. The light receiving element 5 rotates around a rotation center C and receives diffused reflected light indicated by a solid line and position indicated by a dotted line at which specular reflected light is reflected by the half mirror 3 and passes therethrough. You can move to.

In the case where the object to be measured 4 is irregularly reflected paper or the like, it is better to receive the diffuse reflection light at the position shown by the solid line. It is better to receive specularly reflected light at the position indicated by.

For this reason, in the conventional mark detection apparatus, one light receiving element is mounted on a rotating shaft and the light receiving element is rotated to an optimum detection position in order to correct the amount of light reflection according to the object to be measured. I was adjusting.

[0010]

Problems to be solved by the invention As described above, since the light receiving element is rotated around the rotation axis, there are the following problems. Incorrect positioning due to friction of the rotating shaft, play, etc. Position shift occurs due to vibration during use. Since the light receiving element rotates, the lead wire connected to the light receiving element may be disconnected. In order to rotate the light receiving element, it is necessary for the operator to approach the device in operation, which is dangerous.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and provides a mark position detecting device having a stable performance by fixing a light receiving element at a plurality of reflected light guiding positions from an object to be measured. With the goal.

[0012]

In order to achieve the above-mentioned object, a mark position is detected by irradiating a moving object having a mark at a predetermined position with light and detecting reflected light from the mark to detect the mark position. In the device, the light source and the DUT
A half mirror between the
The light is reflected by a half mirror and bent almost perpendicular to the reflected light path.
Providing a first light receiving element on the bent optical path;
Near the point where the light from the light source
A second light receiving element is provided in the direction, so that the output of the light receiving element at a position corresponding to the type of the object to be measured can be selected.

[0013]

[Action] The specularly reflected light is bent almost at a right angle by a half mirror.
A first light receiving element placed on the optical path, and a second light receiving element
By directing the light source toward the diffuse reflection optical path.
Can be downsized. According to the material of the device under test, light receiving elements can be fixed and mounted at the respective optimum light receiving angle positions, and the output of the light receiving device can be selected and taken out according to the device under test. Since the light receiving element is fixed, troubles such as displacement, disconnection, etc. caused by rotation do not occur. In addition, it is only necessary to select the optimum output of the light receiving element, and since this selection is the selection of the electric signal, the selection can be made at a place remote from the operating device.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram illustrating an optical system according to the present embodiment. In the figure, 1 is a light source, 2 is a lens for condensing the light of the light source 1,
3 is a half mirror for transmitting light and reflecting and condensing light, 4
Is an object to be measured such as a web, 5 is a light receiving element, and 6 is a support for fixing the light receiving element 5. The light receiving element 5 is installed at a position where it can receive diffuse reflected light from the DUT 4 and at a position where it can receive regular reflected light. The outputs of the two light receiving elements are switched by a switch at a position not shown in the figure, and one of them is output.

Next, the operation will be described. The diffusely reflected light and the specularly reflected light from the moving object to be measured 4 are simultaneously received and detected by the respective light receiving elements 5, but the diffusely reflected light receiving element and the specularly reflected light receiving element have different light receiving methods. The state of the light receiving signal is also different. If the device under test 4 is irregularly reflected paper or the like, the output of the diffuse reflection light receiving element is selected. In the case of aluminum foil, film, silver printing, or the like, which is close to specular reflection, the output of the regular reflection light receiving element is selected.
This selection may be made by an operator using a switch in accordance with the type of the DUT 4.

As described above, since the selection of the output of the light receiving element is the switching of the electric signal, the operation can be performed at a place away from the operating apparatus, and the operation is safe.

Further, since each light receiving element is fixed to the supporting portion 6, the light receiving angle does not fluctuate, and no displacement occurs due to vibration. Also, since there are no movable parts, cutting of the lead wire and the like does not occur.

[0018]

As is clear from the above description, according to the present invention, the light receiving element is fixed at a plurality of reflected light guiding positions, and the optimum output of the light receiving element is selected and output according to the measured object. It is possible to prevent inconvenience caused by making the light receiving element movable. Further, the selection of the output signal can be performed from a position remote from the apparatus. Also, half-mi
By reflecting specularly reflected light at almost right angles
The entire device can be reduced in size.

[Brief description of the drawings]

FIG. 1 is a diagram showing an optical system according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a basic configuration of overprinting.

FIG. 3 is a diagram illustrating a register mark.

FIG. 4 is a diagram showing a light receiving system of a conventional mark detection device.

[Explanation of symbols]

 Reference Signs List 1 light source 2 lens 3 half mirror 4 DUT 5 light receiving element 6 support

Claims (1)

(57) [Scope of request for utility model registration] 1. A mark position detector for detecting the mark position by detecting reflected light from the mark is irradiated with light moving object to be measured having a mark at a predetermined position, the light source
A half mirror is installed between the
Specularly reflected light is reflected by a half mirror and is almost perpendicular to the reflected light path
A first light receiving element is provided on the bent optical path,
1 Diffuse reflection of light from the light source near the light receiving element
A second light receiving element is provided in the direction of the set position, and an output of the light receiving element at a position corresponding to the type of the object to be measured can be selected.