JP3378921B2 - Print inspection sensor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a print inspection sensor, and more particularly to irradiating light onto a printing paper surface which is fed and moved in a specific direction and detecting reflected light from the paper surface to detect a defect on the printing surface. The present invention relates to a print inspection sensor having a suitable structure.

[0002]

2. Description of the Related Art In order to determine the quality of a printing surface, the amount of light reflected from the printing surface is radiated in a strip shape on the printing paper surface that is being fed and moved along the paper width direction orthogonal to the feeding direction. There is known a method for detecting and detecting and comparing the amount of reflected light on the standard printing surface with the amount of reflected light on the inspection printing surface. In order to realize this method, a sensor that projects and receives light on a printing surface is used.

Conventionally, as a print inspection sensor of this type,
There is one disclosed in JP-A-5-79997. This has a plurality of light receiving portions on both sides of a light emitting portion that emits light in the width direction of the printing surface. The light receiving section is configured by arranging a large number of light receiving elements in a row on a printed circuit board, and is configured to form an image on the light receiving elements on the printed circuit board via this cylindrical lens array. Each of the light receiving elements on the substrate has a light receiving surface of a parallelogram shape, and a plurality of light receiving elements are arranged so that their oblique sides are adjacent to each other. The print surface is sent so as to be orthogonal to the light receiving element array, and when the reflected light from the print surface is received, a gap is not formed in the scanning region of the light receiving element array to prevent the detection dead zone from occurring.

[0004]

However, in the conventional sensor structure, it is necessary to form the light receiving surface in a parallelogram shape with the light receiving elements arranged in series on the substrate. Since it is necessary to use a light receiving element, there is a problem that the manufacturing cost becomes very high. Further, the substrate on which the light receiving element is mounted needs to be set accurately on the light receiving axis of each element arranged in series, and the light receiving element on the substrate surface must be placed so as to be orthogonal to the light receiving axis. The installation form is limited so that the substrate is arranged orthogonally to the light receiving axis in the sensor casing, and there is a limit to downsizing the sensor.

The present invention focuses on the above-mentioned conventional problems,
Manufacturing cost is significantly reduced by using a general-purpose element as a light receiving element
Also, the layout of the board on which the light receiving element is mounted can be freely set.
Sensor that can be made compact by
I will provide a.

[0006]

In order to achieve the above object, a printing inspection sensor according to the present invention firstly prints by arranging a plurality of light receiving elements along a direction transverse to a feeding direction of a printing surface. In a print inspection sensor that receives reflected light from a surface through an optical lens, a light scatterer is provided on the image forming surface of the lens on the light receiving axis, and the light receiving surface of the light receiving element is provided through the light scatterer. It is possible to irradiate scattered reflected light.

In the first structure, the light receiving element is offset from the light receiving axis, and scattered light from the light scatterer can be incident on the light receiving element which is offset with respect to the light receiving element. The surface of the substrate on which the light receiving element is mounted can be arranged parallel to the light receiving axis or at an acute angle.

[0008]

[0009]

[0010]

According to the above construction, first, the light scatterer is arranged on the light receiving axis, this is placed on the image forming surface of the optical lens, and the reflected light is scattered and received by the light receiving surface of the light receiving element. As a result, the light receiving surface of the light receiving element is irradiated with uniform scattered light,
It is possible to detect with a general-purpose light receiving element without using a dedicated light receiving element having a special light receiving surface. Since a general-purpose element can be used, the cost of the light-receiving element that occupies the main part of the sensor can be significantly reduced, and the cost of the sensor as a whole can be reduced.

Further, when the scattered light from the scatterer is reflected by the reflecting plate and is applied to the light receiving element which is arranged deviated from the light receiving axis, the light receiving element can be arranged freely and the element is mounted. It is possible to set the plate surface of the substrate parallel to the light receiving axis or at an acute angle. Therefore, the width of the sensor casing can be made compact and the sensor can be easily installed in a narrow space, so that the application to a printing device or the like becomes very easy.

[0012]

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the print inspection sensor according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a schematic structure of a print inspection sensor according to an embodiment. As shown in this figure, the sensor is arranged so as to face the printing surface of the printing paper 10 or the like, has a casing 12 along a transverse direction orthogonal to the feeding direction of the printing paper 10, and has an opening formed in the printing paper 10. It is arranged toward. A light projecting unit 14 that irradiates the printing paper 10 with light guided from an unillustrated light source through an optical fiber is attached to the casing 12. The light projecting portion 14 is the center of the casing 12, and the fiber group 16 is arranged so as to distribute the light in the longitudinal direction of the casing 12.
The irradiation line 8 forms an irradiation line along the surface width direction of the printing paper 10 through the opening. The light projecting axis from the light projecting unit 14 is set on a vertical surface along the width direction of the printing paper 10.

Light receiving portions 20 (20R, 20L) are provided on both sides of the light projecting portion 14, that is, on the upstream side and the downstream side in the feeding direction of the printing paper 10, respectively.
The light receiving section 20 is tilted so that its light receiving axis is directed to the light irradiation line on the printing paper 10 at an inclination angle of several tens of degrees with respect to the light projecting axis. For this reason, the casing 12 is provided with a side stay 22 that makes the casing opening tapered,
The light receiving section 20 is attached to the inner surface thereof. A sensor glass 24, which is arranged so as to be orthogonal to the light projecting axis and is transparent to light, is attached to the front ends of both side stays 22, and covers the opening to seal the inside. Therefore, the light emitted from the light projecting unit 14 is emitted to the printing surface of the printing paper 10 via the sensor glass 24, and the reflected light from this irradiation line is also incident on the light receiving unit 20 via the sensor glass 24. It has become a thing.

A specific structure of the light receiving section 20 will be described with reference to FIG. The light receiving unit 20 includes an optical lens 26 that first enters the reflected light from the printing paper 10. The optical lens 26 may be formed of a self-hoc lens array called SLA, and the optical axis of the cylindrical lens group is set so as to be along the light receiving axis so that the transmitted light is imaged at a predetermined focal length. There is. A light scatterer 28 is installed on the light receiving axis and on the image plane of the optical lens 26. This is composed of a light-scattering plate 30 arranged orthogonal to the light-receiving axis and a scattered-light reflecting plate 32 surrounding the light-scattering plate 30. Light is repeatedly reflected by the action of an integrating sphere. The light receiving element 34 is arranged so as to be offset from the entrance of the scattering plate 30 and face the scattered light reflecting plate 32 so that the scattered reflected light uniformly strikes the light receiving surface of the light receiving element 34. Such a light scatterer 2
Since the light is received via 8, the light receiving element 3
4 can use a general-purpose photodiode, and the light-receiving element 34 is arranged deviated from the light-receiving axis in order to receive the reflected light from the scattered-light reflecting plate 32. The light receiving element 34 is mounted on the printed circuit board 36. Because of the degree of freedom of arrangement of the light receiving element 34, the board surface of the substrate 36 is parallel to the light projecting axis in the embodiment. It is attached inside the casing 12. Therefore, it is not necessary to dispose the printed circuit board 36 orthogonally to the light receiving axis, which allows the width dimension of the casing 12 to be significantly reduced. A wiring connector 38 is attached to the printed board 36, and a detection signal can be output from the upper end surface side of the casing 12 via the wiring connector 38.

[0017]

[0018]

As shown in FIG. 1 (1), the light receiving section 20 is configured such that the optical lens 26 and the light scatterer 28 are fixed as a unit to the side stay 22 via the mounting bracket 46, and the position of the bracket 46 is fixed. A pull screw 48 and a push screw 50 are provided so as to be adjustable from the outer surface of the side stay 22, and the light receiving axis can be set by adjusting these screws.

According to such an embodiment, the light receiving element 34
Since the image-scattering reflected light is scattered by the light scatterer 28 so that it is reflected and made incident, the general-purpose light-receiving element can be used. Further, since the light receiving element 34 can be deviated from the light receiving axis, the degree of freedom of arrangement of the printed circuit board 36 on which the light receiving element 34 is mounted is increased. In the embodiment, the substrate 36 is installed in parallel with the light projecting axis, and the sensor itself. Is being made compact.

[0021]

As described above, according to the present invention,
Since a light scatterer is arranged in the light receiving part and the scattered light is made incident on the light receiving element, a general-purpose product is sufficient for the light receiving element to be used, which can reduce the sensor cost and the arrangement of the light receiving element. Since the plate surface of the printed circuit board on which the sensor is mounted can be freely arranged, the sensor can be made compact because the plate surface of the printed circuit board can be arranged parallel to the light receiving axis or at an acute angle.

[Brief description of drawings]

FIG. 1 is a sectional view and a front view of a sensor according to an embodiment.

FIG. 2 is a layout configuration diagram of a light receiving unit.

[Explanation of symbols]

10 printing paper, 12 casing, 14 light projecting section, 16 optical fiber group, 18 condensing lens, 20 light receiving section, 22 side stays, 24 sensor glass, 26 optical lens, 2
8 light scatterer, 30 light scatterer, 32 scattered light reflector, 3
4 light receiving element, 36 printed circuit board, 38 wiring connector ,
46 mounting bracket, 48 draw screw, 50 push screw .

Claims (2)

(57) [Claims] 1. A printing inspection sensor in which a plurality of light receiving elements are arranged along a direction crossing a feeding direction of a printing surface, and the reflected light from the printing surface is received via an optical lens, wherein the lens on the light receiving axis is provided. A print inspection sensor, characterized in that a light scatterer is provided on the image forming surface, and the scattered light can be irradiated onto the light receiving surface of the light receiving element through the light scatterer. 2. The light receiving element is arranged offset from the light receiving axis, and the scattered light from the light scatterer can be incident on the light receiving element, and the light receiving element is mounted on the light receiving element. 2. The print inspection sensor according to claim 1, wherein the substrate surface to be formed can be arranged in parallel or at an acute angle with the light receiving axis.