JPS62148840A - Surface inspecting device for article with mark - Google Patents

Abstract

PURPOSE:To securely mask an output signal in real time when a mark is detected by providing a blanking circuit with a start position confirming circuit which includes a zero detecting circuit for detection and a holding circuit for closing an AND circuit when the output is not zero. CONSTITUTION:A camera 1 for defect inspection is set facing the surface of an article 30 to be inspected such as a suspension insulator and while the article 30 is rotated on its axis, reflected light beam from two close lines 41 and 42 on the surface of the article are photodetected by two CCD line sensors 8 and 9 of each camera 1 for defect inspection. If there is a defect 50 or mark 60 present on the article surface, only one of the CCD line sensors 8 and 9 detects it momentarily without fail, so the outputs of the both becomes dissident and their difference signal is generated by a differential arithmetic circuit 10. The difference signal is digitized by an A/D converting circuit 11 and then made into pulses by a clock signal generator 12 and a gate circuit 13. The obtained pulse signal is utilized for surface inspection.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is directed to a marked article that can be optically inspected for the presence or absence of surface defects on an article that has a complex shape and has marks on its surface. This invention relates to a surface inspection device.

(Prior Art) Conventionally, an inspection device equipped with a CCD line sensor on the lens axis of a television camera has been used to inspect surface defects on flat articles. In this inspection, the influence of uneven illumination on the surface hides changes in the intensity of reflected light due to defects, making it impossible to perform accurate inspection. Therefore, the present inventor used two CCD line sensors to receive reflected light from two adjacent lines on the surface of an article, and calculated the difference between the output signals of both to cancel the effects of uneven illumination. Invented an inspection device using the following methods and proposed it earlier in Japanese Patent Application No. 1983-67016. However, when inspecting an article such as an insulator that has marks on its surface, it has become clear that it is necessary to remove the output signal due to the marks in order to prevent malfunctions due to mark detection. For this purpose, it is possible to import all output signals into the computer's memory and then process the images, but the processing takes time and is not suitable for online inspection, and the output signals are masked by marks in real time. is required to do so.

Moreover, in the case of a rotating object such as an insulator, the CCD line sensor may detect the mark at the start of the inspection, and in this case, it is difficult to completely mask the output signal due to the mark. It turns out that there are some issues.

(Problems to be Solved by the Invention) The present invention solves the conventional problems as described above, and can reliably mask the output signal in real time when a mark attached to the surface of an article is detected. It was completed for the purpose of being a surface inspection device for marked articles.

(Means for solving the problem) The present invention uses two CCD line sensors that receive reflected light from two adjacent lines on the surface of an article, and pulses the difference signal between the outputs of each CCD line sensor. It consists of an arithmetic circuit that inputs an input to an AND circuit for generating a defective signal via a delay circuit, and a blanking circuit that issues a blanking signal and closes the AND circuit when a mark is detected by the arithmetic circuit. The blanking circuit includes a start position confirmation circuit that includes a zero detection circuit that detects that the output from the arithmetic circuit is zero at the start of the test, and a holding circuit that closes the AND circuit when the output is not zero. It is characterized by the fact that it has been provided.

(Example) Next, the present invention will be explained in detail with reference to the illustrated example.
In Figures 1 and 2 (11 is a defect inspection camera;
(2) is its output calculation device. Defect inspection camera +
Reference numeral 11 includes a reflecting mirror (4) mounted on the axis of the lens (3) so as to be movable back and forth, and this reflecting mirror (4) has two reflecting surfaces at target positions sandwiching a ridgeline (5) perpendicular to the axis. (6)
, (7). Two CCD line sensors (8) and (9) are installed on the inner surface of this defect inspection camera (11), and the proximity of the product surface is divided into right and left by two reflective surfaces (6) and (7). Figure 3 shows the circuit built into the output calculation device (2), and O shows the two CCD line sensors (8).
), a differential calculation circuit that calculates the difference signal of the outputs of (9), (
11) is an A/D conversion circuit that compares the obtained difference signal with a reference value and converts it into a binary digital signal; (12)
is a clock signal generator, (13) is an A/D conversion circuit (1
This is a gate circuit for counting the time width of the output signal of 1) using a clock signal.

The arithmetic circuit (14) constituted by these two C
When the output of the CD line sensor (8) causes a discrepancy due to the detection of a surface defect or mark, it will emit a pulse signal corresponding to the length, and this pulse signal will be delayed by the delay circuit (15). After that, it is input to the AND circuit (16) which passes the defective signal.

(17) is a blanking circuit that emits a blanking signal when a mark is detected, and the blanking circuit (I7) includes an AND circuit (18) and a mark detection circuit (1).
9), a blanking signal generation circuit (2o), and a start position confirmation circuit (21). When the mark detection circuit (19) detects a mark, the arithmetic circuit (14)
This is a circuit that identifies marks by utilizing the fact that the number of pulses emitted from a defect is orders of magnitude higher than the number of pulses generated by a defect, and the blanking signal generating circuit (20) detects this when a mark is identified. This circuit generates a blanking signal of a corresponding length and closes the AND circuit (16). As shown in the figure, the output of the mark detection circuit (19) is fed back to the AND circuit (18) after detecting the mark.

In addition, as shown in Fig. 4, the start position confirmation circuit (21) has a counter (22) for the integrated value of the number of pulses in two or three scans immediately before the start of the test, and the number of pulses counted by this counter (22). A zero detection circuit (23) that detects that the is zero and generates an H output, and a holding circuit (23) that holds the output of this zero detection circuit (23) for one test period.
24) and a gate circuit (25). Therefore, when pulses are counted during 2 to 3 scans immediately before the start of the test, the zero detection circuit (23) produces an L output, and this L output is transmitted by the holding circuit (24) to the gate circuit (25) and ( 16) is closed and the test is not started. That is, as shown in FIG. 3, this start position confirmation circuit (21) also inputs the output of the holding circuit (24) to the above-mentioned AND circuit (16). When pulses are counted in one scan, the AND circuit (16) is closed together with the gate circuit (25) (Function) Next, the operation of the surface inspection apparatus of the present invention will be explained with reference to FIGS. This will be explained in detail.

As shown in FIGS. 5 and 6, an appropriate number of defect inspection cameras (11) are set facing the surface to be inspected of an article (30) such as a suspended insulator, and the article (30) is Each defect inspection camera (1) rotates around the
The two lines (41) and (4) close to each other on the surface of the article are
2) two CCD line sensors (8),
(9) to receive the light. If there are no defects or marks on the surface of the article, these two CCD line sensors (8)
, (9) are equal and the difference signal is zero, so the arithmetic circuit (14) produces an L output, and the AND circuit (16)
remains closed and produces no fault signal. However, as shown in Figure 5, there are defects (50) and marks (6) on the surface of the product.
0), one CCD line sensor (
Since there is always a moment when only 8) or (9) is recognized, the outputs of the two become inconsistent as shown in FIGS. 7(A) and 7(B), and the differential arithmetic circuit Om (
A difference signal like C) is obtained, and the A/D conversion circuit (11)
The signal is converted into a digital difference signal as shown in FIG. 7(D), and then pulsed as shown in FIG. 7(E) by the clock signal generator (12) and gate circuit (13). The surface inspection is performed using the pulse signal obtained in this way, but in the present invention, the operation differs depending on whether or not the arithmetic circuit (14) generates a pulse signal immediately before the start of the inspection, so it is not classified. I will explain.

■When no pulse signal is generated immediately before the start of the test As is clear from Figure 3, the output of the arithmetic circuit (14) is output from the blanking circuit (14) regardless of whether it contains a pulse signal or not.
17) and the start position @ iq circuit (21
) counts the number of pulses in two to three scans immediately before the start of the test. If this count number is zero, the zero detection circuit (23) in FIG. In addition to generating an output, this start position confirmation circuit (
The H output of the holding circuit (24) in 21) is connected to the AND circuit (1
6) via line (26). In this state, a pulse signal as shown in FIG. 7(E) is transmitted to the calculation circuit (1
4), the mark detection circuit (19) distinguishes between the pulse signal due to the mark and the pulse signal due to the defect, and the blanking signal generation circuit (20) sets the mark width as shown in FIG. 7(F). generate a corresponding blanking signal,
This blanking signal is input to the AND circuit (16) via the line (27). On the other hand, the output from the arithmetic circuit (14) as shown in FIG. 7(E) is appropriately delayed by the delay circuit (15) and then input to the AND circuit (16) through the line (28). Therefore, the AND circuit (1
6) is logically ANDed with this ([rito(F)), and a defective signal containing only the defective signal as shown in FIG. 7(G) is generated. 60)
It goes without saying that the same operation will occur even if the marks (60) are not on the same lines (41) and (42), and even if the entire circumference of the article is scanned, the marks (60) In some cases, it is also possible to issue a warning that the mark has been forgotten.

■If a pulse signal is generated just before the start of the test If the calculation circuit (14) generates a pulse during the 2 to 3 scans on the garment just before the start of the test, the start position z 6m recognition circuit (21)
produces an L output, so the AND circuit (16) connects the line (2
6), and even if a pulse signal is input from line (28) after that, no fault signal is generated. Then, the pulses during two to three scans are counted again, and the inspection is started when the count reaches zero.

(Effects of the Invention) As is clear from the above description, the present invention is capable of detecting surface defects on articles with complex shapes such as insulators without being affected by uneven illumination. Even if a mark is attached, the mark can be identified as a defect and only the defect can be inspected.Also, if a mark, etc. is detected just before the start of the inspection, the timing of the start of the inspection can be shifted and the inspection starts from the normal part. This is to eliminate mark masking errors by starting the mark. Therefore, the present invention is suitable for surface inspection of insulators and other articles with marks on their surfaces, and will greatly contribute to the development of industry.

[Brief explanation of drawings]

Fig. 1 is a horizontal sectional view showing an embodiment of the present invention, Fig. 2 is a vertical sectional view thereof, Fig. 3 is its circuit diagram, Fig. 4 is a circuit diagram of the start position confirmation circuit, and Fig. 5 is the state in use. FIG. 6 is a partially cutaway perspective view showing the state of use, FIG.
The figure is an output waveform diagram of each part of the circuit. (8), f91: CCD line sensor, (14)
: Arithmetic circuit, (16): AND circuit, (17):
Blanking circuit, (21): Start position confirmation circuit, (23): Zero detection circuit, (25): Gate circuit, (60): Mark.

Claims (1)

[Claims] Two CCD line sensors (8) and (9) that receive reflected light from two adjacent lines on the surface of the article, and each CC
an arithmetic circuit (14) that pulses the difference signal between the outputs of the D line sensors (8) and (9) and inputs the pulsed signal to an AND circuit (16) for generating a defective signal via a delay circuit (15); The blanking circuit (17) generates a blanking signal and closes the AND circuit (16) when the mark (60) is detected by the circuit (14). The arithmetic circuit (
a start position confirmation circuit (21) that includes a zero detection circuit (23) that detects that the output from 14) is zero; and a holding circuit (24) that closes the AND circuit (16) when the output is not zero; ) A surface inspection device for marked articles.