JPS6312250B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting defects that cause perspective distortion in a transparent plate such as a plate glass.

More specifically, a transparent plate such as a plate glass is irradiated with light under predetermined conditions, the light that passes through the transparent plate projects an image on a screen, and this is electrically processed and inspected. The present invention relates to a method for detecting distortion defects in a transparent plate, which automatically and accurately detects defects present on the entire surface that distort the transparent view, and improves the visibility securing performance of windshields of automobiles and the like.

In recent years, perspective distortion has become a problem as a basic performance of windshields for automobiles and the like. What is perspective distortion?
It refers to a defect that distorts the transparent view of the front, etc. that can be seen from the passenger compartment.In recent years, glass products used in automobiles, etc. have become thinner and the mounting angle has become sharper. Therefore, strict inspection is required in order to reduce the above-mentioned perspective distortion.

However, in the current state of inspection for perspective distortion, all inspections are performed by visual sensory inspection, which can result in large variations in inspection results depending on the inspector, and the need to conduct a large number of inspections. There are problems such as failure to perform the test, and furthermore, many inspections being omitted, requiring re-inspection.
In particular, since it requires manual work, inspection standards cannot be sufficiently raised, and the number of inspections cannot be increased, which has caused major problems in terms of manufacturing costs and quality improvement.

In view of the above-mentioned problems, the present inventors have created the present invention in order to effectively solve the problems.

The purpose of the present invention is to automate the inspection of perspective distortion using optical system equipment and electrical system equipment, speed up the inspection work, and enable automatic online inspection, thereby saving labor and reducing costs. An object of the present invention is to provide a method for detecting distortion defects in a transparent plate, which is intended to improve quality.

Therefore, the present invention irradiates a light beam that has an incident angle oblique to the plate surface of a transparent plate and has a constant opening angle, and the light beam that passes through the transparent plate projects a transmitted image, and the movement of the transmitted image is Changes in the electrical signal on a monitoring inspection line that crosses the direction are converted into a video signal, the video signal is differentiated and then clipped at a predetermined level voltage, and the remaining video signal after being clipped is converted into a pulse signal. The gist is to detect the presence of a defective image on a transparent plate based on the presence or absence of the pulse.

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

1 is a glass used as a windshield of an automobile, which is an object to be inspected, and the glass 1 moves on a conveyor roller 2. The object to be inspected is a transparent body in the shape of a plate or a curved plate.

A reflector 3 is placed below the roller 2 in an inclined position.
is provided, and a screen 4 is provided above the roller 2 in an inclined position. A light source 5 is placed at an appropriate location with respect to the reflecting mirror 3 and screen 4, and a first
A light beam L as shown in the figure is irradiated. The light source includes
A xenon lamp, a mercury lamp, a laser emitter, etc. are used. Therefore, when the glass 1 that has been moving on the roller 2 reaches the position shown in FIG. It will be shown. Actually, glass 1
A predetermined condition must be satisfied between L and L, and this is schematically shown in FIG.
The angle between the center line l ₁ of the light ray L and the normal l ₂ of the object to be inspected 1', that is, the angle of incidence, is 30° or more (preferably 50° or more and 80° or less), and The length a of the light emitting portion is set to 40 mm or more (preferably a dimension that covers the entire width of the object to be inspected 1').
In addition, the angle from which the point light source 5' looks toward the light emitting part of the object to be inspected 1', that is, the opening angle θ of the luminous flux, is within the range of -15° (in the case of convergent light) to +15° (in the case of diffused light). It is better to do so.

In other words, if the absolute value of the angle θ is too large, there will be a large difference in the angle of incidence between the center and the periphery of the light beam, and this will cause the contrast of the defect image to vary greatly depending on the location where it appears. However, if the above range is used, this variation can be suppressed to a small level,
Stable detection accuracy can be obtained.

In FIG. 2, the case where light is projected from above the object to be inspected 1' has been explained, but the conditions are the same for the case where the light is emitted from below the object to be inspected 1 as shown in FIG.

Reference numeral 6 denotes a nozzle for blowing out air, which is provided to keep the surface of the reflecting mirror 3 clean at all times.

Reference numeral 7 denotes an imaging device, which captures a transmitted image of the glass 1 projected on the screen 4. As the imaging device, a television camera, a line sensor camera (such as a CCD camera), a sensor camera in which photoelectric conversion elements are arranged two-dimensionally, or the like is used. The transmitted image of the screen 4 is converted into an electrical signal by an imaging device 7, and this signal is processed by a device 9 that processes a video signal, which is a video signal controlled by a computer 8, and the processing result is displayed on a monitor 10. to be displayed. In the monitor 10, reference numeral 11 indicates a monitoring inspection line provided in a direction transverse to the direction of movement of the glass position, and a video signal is inspected along this inspection line 11 to detect defects.

The processing of the video signal is as follows. As shown in FIG. 3, the inspection line 11 detecting the defect image 13 in the transmitted image 12 of the glass is converted into an electrical signal into a video signal as shown in FIG. 4A. The video signal is shown in Figure 4B.
After differential processing is performed as shown in Fig. 4C, the remaining voltage is clipped at an appropriate level voltage.
Pulsing is performed as follows. In the signals shown in FIG. 4A, 14 and 15 indicate start and end synchronization signals, and 16 and 17 indicate glass edge detection signals. As a result of the above, the defect image 1 is displayed on the monitor 10.
3 can be detected by pulse 18. In FIG. 4, b indicates the inspection range, and c indicates the range where the presence of the arrow point is not allowed. In other words, the distortion defects that exist near the edges of the glass 1 are ignored in the inspection because they are hidden by the attached state of the glass. The video signal processing as described above is continuously repeated as the glass 1 moves. In this case, the interval between the edge detection pulses 19 and 20 of the glass 1 changes depending on the relative position of the monitoring inspection line 11 and the transmitted image 12.

When a defect that causes perspective distortion exists in the glass 1, a defect image is generated on the screen 4. The appearance of the defect image differs depending on the cause of the distortion. For example, if the glass is laminated glass and the cullet is inserted into the interlayer film, if the glass plate contains a foreign glass with a high refractive index, or if there are bubbles in the glass plate. If it exists, a light condensing effect will occur and it will appear white with higher brightness than the surrounding area. Furthermore, if there is a local dent in the glass or if the interlayer film of the laminated glass is doubled, etc., a diffusion effect or a light absorption effect occurs, making the glass appear darker than the surrounding area. Also, the larger the incident angle of the light beam, the stronger the contrast of the defect image on the screen. The defect image as described above is captured by the imaging device 7 and detected on the monitor 10 by the above-described operation.

Furthermore, in the above embodiment, by interposing a condenser lens between the light source 5 and the reflecting mirror 6,
It is also possible to set the aperture angle θ of the luminous flux l mentioned above within a predetermined range.

As is clear from the above description, according to the present invention,
The moving object to be inspected is irradiated with light, the transmitted image is projected on a screen, and this transmitted image is electrically processed to detect defects in the inspected object that cause perspective distortion. It is possible to automate inspections, which enables online automatic inspections, which saves labor and speeds up work, reduces costs, and eliminates visual inspections, which eliminates variations in inspection ability and improves quality. It exhibits various features such as being able to achieve improvements in performance.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a diagram showing the configuration of an apparatus for carrying out the method according to the invention, FIG. 2 is a diagram illustrating various conditions related to light rays, and FIG. 3 is a defect image of a transmitted image. FIG. 4 is a system diagram for processing electrical signals. In the drawings, reference numeral 1 indicates a glass object to be inspected, 3 a reflecting mirror, 4 a screen, 5 a light source, 7 an imaging device, 9 an electric signal processing device, and 10 a monitor.

Claims (1)

[Claims] 1. A light beam having an incident angle inclined to the plate surface of a transparent plate and having a constant opening angle is irradiated, the light beam passing through the transparent plate projects a transmitted image, and monitoring is carried out across the moving direction of the transmitted image. Converting changes in the electrical signal on the inspection line for use into a video signal, differentially processing the video signal, and then clipping it at a predetermined level voltage;
A method for detecting distortion defects on a transparent plate, comprising: converting the remaining video signal after being clipped into a pulse signal, and detecting the presence of a defect image on the transparent plate based on the presence or absence of the pulse.