JPS61204548A - Defect detector - Google Patents

Abstract

PURPOSE:To perform position detection at a high speed by providing a photodetector which photodetects only scattered light with a small angle of expansion among flank scattered light beams which leak out from flanks of a body to be inspected as to light scattered by a defect in the body to be inspected. CONSTITUTION:A laser light source 21, a condenser lens 22 for obtaining a specific beam diameter, laser light 23, and a scanning mirror 24 for scanning a specific range of the body 29 to be inspected are provided, and an oscillating mirror or rotary polygon mirror is used as the scanning mirror 24. Many photodetectors 25 are arranged on flanks of the body 29 and flank scattered light 26 from the defect 27 in the object body 29 is photodetected to output an electric signal 28. When a hood 32 is fitted to a photodetector 25, the flank scattered light 26 from the defect 35 in the object body 29 is photodetected, but flank scattered light 38 from a defect 27 at distance is not photodetected. The photodetectors 25 which are allowed to photodetect only the flank scattered light 26 traveling straight are placed on the flanks at intervals to detect the position of the defect 35.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a defect detection device for detecting surface defects and internal defects in transparent objects.

[Conventional technology]

Transparent objects generally have scratches or bubbles during manufacturing.

Defects such as foreign matter may occur. This defect weakens the strength and impairs the aesthetic appearance, so all products must be inspected and removed during manufacturing. At this time, knowing the position of the defect in the transparent object is important for improving manufacturing technology. This type of inspection has generally been carried out by visual inspection, but there is a need to automate the inspection in order to improve inspection efficiency, uniformity, and accuracy. Therefore, conventionally, defects have been detected using a defect detection device as shown in FIG. That is, the laser beam 3 irradiated from the laser light source 1 is made into a predetermined beam diameter by the condensing lens 2,
This laser beam 3 is transmitted to a laser scanning mirror 4 (oscillating mirror)
The transparent object 9 to be inspected is scanned by the 3D device 9, and is converted into a side scattering signal 8 generated by hitting the defect 7. This electric signal 8 is used to check the presence or absence of defects, and a digital position signal 15 is obtained by a scanning angle detection section 14 based on an analog position signal 13 output from a driver 11 of the laser scanning mirror 4. Note that 12 is a mirror drive signal.

[Problems to be solved]

However, in such a conventional defect detection device, the scanning angle detection section 14 is required to detect the position of the defect, and it is also necessary to synchronize the position signal 15 and the electrical signal 8. Further, the scanning speed is limited by the scanning angle detection section 14, and there is a limit to increasing the speed.

[Means for solving problems]

This was developed in order to solve these conventional problems, and as a means of solving this problem, a transparent object to be inspected is irradiated with a beam of light, and internal defects and surface defects are detected from the scattered light. The defect detection device KTh detects
A means for holding a transparent object to be inspected in a predetermined position, a means for irradiating a beam of light onto the object to be inspected, and a means for irradiating a beam of light onto the object to be inspected; The present invention provides a defect detection device characterized by comprising a photodetector installed to be able to detect the position of a defect by receiving only the scattered light with a small spread angle among the emitted side scattered light.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, 21 is a laser light source, 22 is a condensing lens for obtaining a predetermined beam diameter, 23 is a laser beam, and 24 is a condenser lens for obtaining a predetermined beam diameter.
is a round scanning mirror that scans a predetermined range of the object to be inspected 290, and uses a polygon mirror that rotates once as a vibrating mirror. 25 is a photodetector, which is placed in large numbers on the side of the object to be inspected 29;
The side-scattered light 26 from the defect 27 inside is received and an electrical signal 28 is output. Note that 30 is a mirror driver for laser scanning, and 31 is a mirror drive signal. Figure 2 is the first
This is a diagram when the figure is viewed from above, and the hood 3 is attached to the photodetector 25.
2, the side scattered light 26 of the defect 35 in the object 29 to be inspected can be received, but the side scattered light 38 of the defect 27 located at a distant position cannot be received.

The position of the defect 35 can be detected by placing the photodetector 25, which is designed so that it can receive only the side scattered light 26 traveling in a straight line, on the side without any gap. In addition, 3
4 is an electrical signal.

In this embodiment, the hood 32 is used to remove the side-scattered light 38 having a large angle, but a glass fiber, a plastic fiber, or a porous cylinder may be used. In addition, the photodetector 25 in FIG. 3 can detect the position in the Y-axis direction, but the photodetector 25 placed on the other side causes the position of the Y-axis bar to be between Hide and H. The position within the cylindrical object 29 is determined.

〔Effect of the invention〕

According to the present invention, in a defect detection device that irradiates a transparent object to be inspected with a beam of light and detects internal defects and surface defects from the scattered light, means for holding the transparent object to be inspected at a predetermined position. a means for irradiating a beam-shaped light beam onto an object to be inspected; and a means for irradiating a beam-shaped light beam onto an object to be inspected, and scattered light with a small spread angle among the side scattered light that exits from the side of the object to the outside of the object among the light scattered by defects existing in the object to be inspected. Since the defect detection device is equipped with a photodetector that is installed so that it can detect the position of the defect by only receiving light, it is possible to detect the position of the defect on the object to be inspected at high speed. This has the effect of improving quality control on the line, etc.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a defect detection device according to an embodiment of the present invention, FIG. 2 is an explanatory diagram of FIG. 1 viewed from above, and
FIG. 3 is an explanatory diagram showing a conventional defect detection device.

Claims (1)

[Claims] In a defect detection device that irradiates a transparent object to be inspected with a beam of light and detects internal defects and surface defects from the scattered light, there is provided a means for holding the transparent object to be inspected in a predetermined position, and a means for holding the transparent object to be inspected at a predetermined position; means for irradiating a beam of light;
Optical detection installed to detect the position of a defect by receiving only the scattered light with a small spread angle among the side scattered light emitted from the side of the object to the outside of the object, out of the light scattered by defects existing in the object to be inspected. A defect detection device comprising: