JPH0247444Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a defect inspection camera used to optically inspect the presence or absence of surface defects of objects having complex shapes.

(Prior art) Conventionally, for defect inspection of plate-like objects such as plate glass and steel sheets, a linear image sensor with a large number of pixels arranged in a straight line is placed on the axis of the lens of a television camera. However, since these defect inspection cameras convert the brightness of the object's surface into a linear electrical signal, they can be used to inspect objects with complex uneven surfaces such as insulators. When used on objects, there is a drawback that it is not possible to distinguish between changes in brightness due to uneven illumination and changes in brightness due to defects. Therefore, the inventor proposed a method to cancel the effects of uneven illumination by arranging two linear image sensors in parallel in close proximity to the imaging surface of a television camera, and calculating the difference between the output signals generated from both linear image sensors. A visual sensor system was developed and proposed in Japanese Patent Application No. 59-67016.

(Problem that the invention aims to solve) However, in general, a linear image sensor has a shift register circuit and an output circuit integrated around its sensor chip, and has an overall width of about 10 mm. It is not possible to place them close together.
If the lens magnification is M, on the surface of the object
It has been found that there is a problem in which the inspection accuracy cannot be improved beyond a certain value because brightness on lines separated by 10×Mmm must be compared.

(Means for solving the problems) This invention solves the conventional problems as mentioned above,
It was developed for the purpose of being a defect inspection camera that can compare the brightness of two very close lines on the surface of an object using a normal linear image sensor. A reflecting mirror with two symmetrical reflecting surfaces tilted at equal angles to the axis is installed across a ridge line perpendicular to the axis, and two positions on the inner surface of the camera that receive the reflected light from these reflecting surfaces are installed. , are each characterized by having a linear image sensor arranged therein.

(Embodiment) Next, the present invention will be described in detail with reference to the illustrated embodiment. 1 is a camera body equipped with a lens 2, and 3 is a camera main body equipped with a lens 2 by a feed screw 4 and a guide 5. It is a pentagonal columnar reflector that is mounted so that it can move forward and backward. This reflecting mirror 3 has two symmetrical reflecting surfaces 7 and 8 that are inclined left and right at equal angles of 45 degrees to the axis l, with a ridge line 6 positioned perpendicular to the axis l in between, and , linear image sensors 9 and 10 are arranged at two positions on the inner surface of the camera that receive reflected light from these reflecting surfaces 7 and 8, respectively. Figures 3 and 4 are the second part of this invention.
This shows an example in which the reflecting surfaces 7 and 8 of the reflecting mirror 3
The angle formed by the lens 2 with respect to the axis 1 of the lens 2 is about 85 degrees, and the linear imaging elements 9 and 10 are therefore arranged at the front position of the inner surface of the camera. Further, in the second embodiment, the reflecting mirror 3 is moved forward and backward in the direction of the axis l by a piezoelectric drive device 11, thereby improving the accuracy of forward and backward movements.

(Function) As shown in FIG. 5, the device configured as described above aligns the radial direction of the object 20 with the longitudinal direction of the ridgeline 6 of the reflecting mirror 3 above the object 20 such as a suspended insulator. The object 20 is rotated on its own axis and the reflected light from the surface is received by the lens 2.The incident light from the lens 2 is reflected by the reflecting mirror 3 installed on the axis l of the object 20. axis l
It is divided into left and right halves by two symmetrical reflecting surfaces 7 and 8 tilted at equal angles to the axis l across a ridge line 6 perpendicular to the ridge line 6, and receives reflected light from these reflecting surfaces 7 and 8. The object 2 is received by the linear image sensors 9 and 10 arranged at two positions on the inner surface of the camera.
This is converted into an electrical signal indicating a change in brightness in the radial direction of 0, and is processed by the arithmetic processing unit 12. At this time, as is clear from FIGS. 1 and 3, the light rays incident from the optical path slightly deviated to the left or right from the axis l are distributed by either the reflecting surfaces 7 or 8 and are directed to the linear image sensor 9. or 10, and the distribution of the light beams with such a slight difference in optical path is performed by the reflecting mirror 3, so the linear imaging devices 9 and 1
It is possible to accurately grasp the brightness on the two very close lines 21 and 22 on the surface of the object 20 and convert it into an electrical signal by the linear imaging elements 9 and 10 without arranging the 0 in close proximity. Become. Furthermore, if the reflecting mirror 3 is made to move forward and backward along the axis l, when the reflecting mirror 3 is moved forward, the optical path of the light beam entering the linear image sensors 9 and 10 will be moved away from the axis l, and conversely, the reflecting mirror 3 will be moved backward. As a result, the light rays in the optical path close to the axis l enter the linear image sensors 9 and 10, and the interval between the contrasting lines 21 and 22 on the surface of the object 20 can be freely changed within a certain range. It becomes possible.

If there are no defects on the surface of the object 20, the output signals from the linear image sensors 9, 10 will be different from the corresponding pixels of each linear image sensor 9, 10, although there will be variations in the longitudinal direction. Since the output signals of are the same, if the difference between the output signal from the linear image sensor 9 and the output signal from the linear image sensor 10 is calculated, the difference signal will be zero. On the other hand, if a defect 30 exists on the surface of the object 20 as shown in FIG. The output signal of the linear image sensor 10 that captures the line 22 has a waveform as shown in the middle row of FIG. Therefore, by calculating the difference between the two, it is possible to extract a difference signal containing only the defect signal, as shown in the lower part of FIG. Furthermore, since the distance between the contrasting lines 21 and 22 can be made extremely close, even very fine defects 30 can be detected, and inspection accuracy can be significantly improved. In addition, instead of the reflector 3, the tip is 2.
Although it is possible to guide the light beam to each linear image sensor 10 using optical fiber cables divided into two, the structure becomes complicated, so it is preferable to use the reflecting mirror 3 as in the present invention.

(Effects of the invention) As is clear from the above explanation, this invention converts the brightness on two very close lines on the surface of an object into electrical signals and compares them using a normal linear image sensor. Moreover, since the distance between the two lines to be compared can be freely adjusted, defects on the surface of the object can be accurately and accurately inspected depending on the object. Therefore, the present invention has extremely great practical value as a defect inspection camera that can accurately inspect defects in insulators and other objects with complex uneven surfaces online.

[Brief explanation of the drawing]

Fig. 1 is a horizontal sectional view showing the first embodiment of the present invention, Fig. 2 is a vertical sectional view thereof, Fig. 3 is a horizontal sectional view showing the second embodiment, and Fig. 4 is a vertical sectional view thereof. , FIG. 5 is a partially cutaway perspective view showing the state in which the defect inspection camera of the present invention is used, and FIG. 6 is a waveform diagram of the output signal of each image sensor and the difference signal thereof. 2...Lens, 3...Reflector, 6...Ridge line,
7, 8... Reflective surface, 9, 10... Linear image sensor,
l: Axis line of lens 2.

Claims (1)

[Claims for Utility Model Registration] 1. A reflecting mirror having two symmetrical reflecting surfaces 7 and 8 that are tilted at equal angles to the axis l with a ridge line 6 perpendicular to the axis l on the axis l of the lens 2. 3, and linear imaging elements 9 and 10 are arranged at two positions on the inner surface of the camera that receive reflected light from these reflecting surfaces 7 and 8, respectively. 2. The defect inspection camera according to claim 1, in which the reflecting mirror 3 is movable back and forth along the axis l.