JPH08216378A - Illumination device of inspecting apparatus of printing quality - Google Patents

Abstract

PURPOSE: To realize the remarkable improvement of detecting accuracy of defect, the reduction of production cost and, in addition, the reduction of labour requiring for the maintenance of optical parts. CONSTITUTION: When printing paper surface pivots countercloskwise by (α), the reflex axis 8 of an illuminating light source body 1 pivots also in the same direction by 2α. As a result, the local maximum point of the paper surface illumination distribution 12 by the illuminating light source body 1 after pivoting moves leftwards and the light quantity on the optical axis of a camera increases as the conventional instance does. However, the local maximum point of the paper surface illumination distribution 13 by the illuminating light source body 2 after pivoting moves also leftwards and the light quantity on the optical axis of the camera decreases. Since the light quantities of the illuminating light source bodies increases and decreases relatively with each other, an illuminating device can give a certain fixed light quantity to the camera at all times, even when the printing paper surface shakes due to the fluttering at its holding tail end side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device for a print quality inspection device.

[0002]

2. Description of the Related Art An illumination device of a conventional print quality inspection apparatus will be described with reference to FIG. 3. Reference numeral 5 is a printing paper surface curved in an arc shape on an impression cylinder A, 14 is a camera installed in a detecting portion, and 15 is a detecting portion. A xenon lamp installed at a remote place, 16 is an optical fiber extending from the xenon lamp, 17 is a light source irradiation end formed at the tip of the optical fiber 16, 18 is the optical axis of the light source, and the camera 14 is the optical axis It is arranged so as to be substantially perpendicular to the printing paper surface 5, and the light source irradiation end portion 17 is arranged so that its optical axis is oblique to the printing paper surface 5.

While the printing paper surface 5 is illuminated by the illumination light from the light source irradiation end 17, the image data of the printing paper surface 5 is captured by the camera 14 and the defective paper surface is detected from the captured image data of the printing paper surface 5. It is like this.

[0004]

In the illumination device of the conventional print quality inspection device shown in FIG. 3, one light source system 15 to 15 is used.
Since the printing paper surface 5 is illuminated by the illumination light from 17, the xenon lamp 15 with high illuminance is required. Moreover, since the xenon lamp 15 is installed at a position apart from the detection unit and is guided to the detection unit by the optical fiber 16, the manufacturing cost is high.

A condenser lens or the like is used to effectively send the illumination light from the xenon lamp 15 to the optical fiber 16. This condenser lens and the like have to be maintained for optical deterioration, which requires a great deal of labor. Further, on the gripper side of the printing paper surface 5 on the impression cylinder A, when the detection unit captures image data, the amount of light incident on the detection unit changes due to the flapping of the paper, which greatly affects the correction of the illumination light amount. . That is, when the normal printing paper surface is irradiated with the illumination light from the vertical direction, the illuminance meter 19 is moved vertically and equidistantly with respect to the printing paper surface as shown in FIG. As a result of measurement, the illuminance on the paper surface is generally represented by a curve called a normal distribution, and the illuminance distribution becomes maximum near the optical axis 20 of the illumination.

Here, in the conventional illumination device, as shown in FIG. 5, the illumination light is incident along an incident axis 21 that is oblique to the vertical axis passing through the incident point, and the reflected light is at the same angle in the opposite direction. Since the light is reflected along the emission axis 22 of, the maximum illuminance point on the paper surface is biased from the vertical axis to the reflected light side as shown by the curve in FIG. FIG. 6 is an explanatory diagram showing a change in illuminance on the printing paper surface caused by the flapping of the paper on the gripper side of the printing paper surface on the impression cylinder.

When the flap does not occur on the gripping edge side of the printing paper surface, it has an illuminance distribution shown by a solid line, and the illuminance of the paper surface on the optical axis of the camera is 10. Here, consider the case where the gripper side (the right end in the figure) moves upward. The fluctuation amount is considered to be negligible compared to the distance from the light source and the camera to the printing paper surface, and the printing paper surface rotates around the intersection O between the perpendicular line drawn from the camera to the printing paper surface and the printing paper surface. The fact that the mouth end moves upward means that
That is, the printing paper surface rotates counterclockwise by the angle α.

At this time, the normal line extending perpendicularly to the printing paper surface from the point of intersection O is also rotated counterclockwise by α. Further, the emission axis of the reflected light rotates by 2α, and the illuminance distribution on the printing paper surface also moves the maximum illuminance position to the left as shown by the dotted line. As a result, the amount of light received by the camera changes from 10 to 11. This is the variation in the amount of light received by the camera due to the flapping of the paper.

The present invention has been proposed in view of the above problems, and its object is to significantly improve the defect detection accuracy, reduce the manufacturing cost, and reduce the labor required for the maintenance of optical components. The present invention aims to provide an illuminating device for a print quality inspection device.

[0010]

In order to achieve the above-mentioned object, the present invention is directed to arranging a detecting portion having a light source for illumination and a camera so as to face a printing paper surface curved in an arc shape. In a print quality inspection apparatus for detecting a defective paper surface from image data of a paper surface of a stamp taken in by a unit, it has two illumination light source bodies, and the irradiation optical axis of each illumination light source body is relative to the optical axis of the camera. The respective light source units for illumination are installed so as to be symmetrically inclined and at equal angles.

[0011]

The illuminating device of the print quality inspection apparatus of the present invention is constructed as described above, and when the printing paper surface is rotated by α in the counterclockwise direction, the emission axis of one of the illuminating light source bodies also moves in the same direction.
Rotate by α. Therefore, the maximum point of the illuminance distribution on the paper by one of the illumination light sources moves to the left, and the amount of light on the camera optical axis increases as in the conventional example. However, the maximum point of the illuminance distribution by the other illumination light source also moves to the left, which reduces the amount of light on the camera optical axis. In this way, the light amounts of the one illumination light source and the other illumination light source are relatively increased and decreased, so that the illumination device is always constant with respect to the camera even if the printing paper surface fluctuates due to flapping on the gripping edge side. It will give the amount of light.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An illuminating device of a print quality inspection apparatus according to the present invention will be described below with reference to an embodiment shown in FIG. 1 and
It has a lighting light source 2 and a camera 3. 4 is a camera optical axis, 5 is a printing paper surface curved in an arc shape on the impression cylinder A, 6
Is the incident axis of the light source body 1, 7 is the incident axis of the light source body 2, and the detection unit having the illumination light source body 1, the illumination light source body 2 and the camera 3 is printed in an arc shape on the impression cylinder A. It is arranged so as to face the paper surface 5.

Also, the respective incident light sources 1 and 2 are arranged so that the incident axis 6 of the illuminating light source body 1 and the incident axis 7 of the illuminating light source body 2 are symmetrically oblique and equiangular with respect to the optical axis of the camera 3. Body 1, 2
Is installed. Next, the operation of the illumination device of the print quality inspection device shown in FIG. 1 will be described in detail with reference to FIG.

When the printing paper surface 5 rotates in the counterclockwise direction by α, the emission shaft 8 of the illumination light source body 1 also rotates in the same direction by 2α. Therefore, the maximum point of the illuminance distribution 12 on the paper by the illuminating light source body 1 after the rotation moves to the left, and the light amount on the optical axis of the camera increases as in the conventional example. However, the maximum point of the illuminance distribution 13 on the paper by the illuminating light source body 2 after the rotation also moves to the left, which reduces the amount of light on the camera optical axis. In this way, since the light amounts of the illumination light source body 1 and the illumination light source body 2 relatively increase and decrease, the printing paper surface 5
The illumination device always gives a constant amount of light to the camera 3, even if it fluctuates due to the flapping on the grip side.

Reference numeral 8 is an emission axis of the illumination light source body 1, 9 is an emission axis of the illumination light source body 2, 10 is an illumination distribution on the paper surface by the illumination light source body 11, and 11 is an illumination surface distribution on the paper surface by the illumination light source body 2. is there.

[0016]

As described above, when the printing paper surface rotates in the counterclockwise direction by α as described above, the illumination device of the print quality inspection apparatus of the present invention also rotates the emission axis of one of the illumination light source bodies in the same direction by 2α. To do. Therefore, the maximum point of the illuminance distribution on the paper by one of the illumination light sources moves to the left, and the amount of light on the camera optical axis increases as in the conventional example. However, the maximum point of the illuminance distribution by the other illumination light source also moves to the left, which reduces the amount of light on the camera optical axis.
In this way, the light amounts of the one illumination light source and the other illumination light source are relatively increased and decreased, so that the illumination device is always constant with respect to the camera even if the printing paper surface fluctuates due to flapping on the gripping edge side. The amount of light can be given, and the defect detection accuracy can be significantly improved.

Further, an inexpensive fluorescent lamp or the like can be used as the light source for illumination. Further, it is possible to eliminate the need for optical components such as optical fibers, reduce the manufacturing cost, and reduce the labor required for the maintenance of the optical components.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of an illumination device of a print quality inspection device of the present invention.

FIG. 2 is an operation explanatory view of the lighting device.

FIG. 3 is a side view showing an illumination device of a conventional print quality inspection device.

FIG. 4 is an explanatory diagram showing an illuminance distribution of the illumination device.

FIG. 5 is an explanatory diagram showing a illuminance distribution on a paper surface of the illumination device.

FIG. 6 is an operation explanatory view of the illumination device.

[Explanation of symbols]

 1, 2 Illumination light source 3 Camera 4 Camera optical axis 5 Printing surface curved in an arc shape on the impression cylinder A 6 Incident axis of the light source body 7 Incident axis of the light source body 2

Claims (1)

[Claims] 1. A print quality in which a detection unit having an illumination light source and a camera is arranged so as to face a printing paper surface curved in an arc shape, and a defective paper surface is detected from image data of the printing paper surface captured by the detection unit. The inspection device has two illumination light source bodies, and the illumination light source bodies are arranged so that the irradiation optical axis of each illumination light source body is symmetrically oblique and equiangular with respect to the optical axis of the camera. An illumination device for a print quality inspection device, which is characterized by having a body installed.