JPS58142247A - Tester - Google Patents

Abstract

PURPOSE:To reliably decide a defect part of a fine signal, by a method wherein a delay differentiation of a photographing signal is conducted 2 times, the obtained signal is binary-codes to store it in a memory, and a processing takes place based on a content thereof. CONSTITUTION:A signal (a) from a camera 1 is amplified, and it produces a signal as shown in (b) which is inputted to a differential amplifier 4 and a delay circuit 3. The delay circuit 3 applies a signal (c), delaying by some time, to the differential amplifier 4, and a difference between the signal (c) and the signal (b) is found to perform a first delay differentiation. Then, a good product inclines to some extent, and if a contamination of a defect is present, it is formed into a wave-form which changed in the middle of the inclination. A signal (d), which is delay-differentiated once, is inputted to a differential amplifier 6 and a delay circuit 5, and a second delay differentiation takes place through addition of a delayed signal (e). A signal, on which a delay-differentiated is made two times, is applied to a comparator 7, a negative reference level (g) is added for comparison, and in the case of a good product, the binary-coded signal produces a pulse, and in the case of a bad product, it produces 2 pulses. A signal (h) is inputted to a counter 9 to store it in a memory 11. Meanwhile, an output (f) of the differential amplifier 6 is compared with a reference level (k) by a comparator 8, and an output (l) is stored in a memory 12 to decide a deciding circuit 13.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention stably and accurately inspects the presence or absence of defects on an object to be inspected by appropriately processing an image signal obtained by imaging the object with a television camera or the like. The present invention relates to a defect inspection device.

Generally, in order to automatically inspect defects in industrial products, the object to be inspected is imaged with an imaging device such as a television camera, and the image signal obtained is binarized by comparing it with an appropriate threshold level. By appropriately processing this binarized signal, the presence or absence of a defect O in the object to be inspected is inspected, but the inspection accuracy in this case depends on the accuracy of the binarization process y. For this reason, various methods have been proposed for binarization processing.

FIG. 1 is an explanatory diagram for explaining such a binarization processing blade type.

That is, as shown in Figure P), the inspection object P is read by an imaging device (not shown) by sequentially repeating horizontal scanning in the direction of the arrow in the vertical direction, and an imaging signal as shown in Figure Middle) is obtained. In this case, the object P has the same [&]
Because there is pentacontamination D as shown in ! Same figure 0
-) There is a gentle depression as shown by the arrow in the 0 image. The image signal t obtained in this way
- As a binarization method for binarizing, for example,
There is also O shown in Publication No. 638. This is because most conventional O methods use a fixed level method in which the O threshold level is kept constant for binarization, but this method uses a method that depends on the brightness level of the imaging signal. O
However, it is clear that with this method, it is not possible to detect a gentle hollow sound such as O mentioned above. Note that Diagram 1 (c) shows a binary signal based on a floating level. On the other hand, a method as disclosed in Japanese Patent Laid-Open No. 54-34886 is also known. This can be done by extracting the delayed signal shown by the dotted line from the imaging signal as shown by the O condensed line in the same figure, and by taking the wrinkled vine signal, the imaging signal, and the O condensed line. Obtain the signal and set the scissors mold signal to a predetermined O setting value SP? It is binarized by comparing it with 8M. Therefore, in a normal case, one pulse is obtained at each of the rising and falling edges of the imaging signal as shown in (E) and (F) in the same figure, but if there is a defect, two or more pulses will be obtained, and the defect can be detected by this. do. However, even with this method, it is not possible to detect defects caused by faint dirt as shown by the arrow in the same figure.The present invention was developed in view of the above, and detects minute signals reliably and with high precision. It is an object of the present invention to provide a defect inspection device that performs defect inspection by performing raster scanning of an object to be inspected using an imaging means and delay-differentiating the obtained imaging signal twice. Highlight the defective parts and o1 twice! The signals obtained by the IN differential operation are binarized at different reference levels, the binarized signals are counted for each horizontal scan and stored in memory, and predetermined processing is performed based on the contents of the scissors memory. By doing this, it is possible to detect with high precision even defects that are difficult to detect with conventional methods, such as faint dirt on the object.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a block diagram showing an embodiment of the present invention.
FIG. 3 is a waveform diagram showing the liquid form of each part of the second wJO. In FIG. 2, 1 is an imaging device such as a television camera, 2 is an intensifying circuit, 3.5 is a delay circuit, 4.6 is a differential amplifier circuit,
7 and 8 are comparison circuits, 9.degree. 10 is a counting path, 11 and 12 are meters, 13 is a determination circuit composed of a microcomputer, and 14 is an inspection object Po discharge section. In addition, 1 to h and t in the same figure indicate the signals of each part.
IO with the same symbol also corresponds to O. Also, the 311th &)
(b) shows the case where the object to be inspected is non-defective, (b) shows the case where there is a five-sided stain, and (c) shows the case where there is a defective part.

A television (TV) obtained by imaging the tablet O inspection object P
) The signal from camera l is amplified by amplifier =, and the third
Signals as shown by b in FIGS. The delay circuit 3 applies a signal C obtained by delaying the imaging signal obtained via the amplifier 2 by a certain time to the other terminal of the differential amplifier 40 . Then, the first delay differentiation is performed by taking the difference between the signal C delayed in the differential amplifier 4 and the signal C before being delayed (see waveform d in FIG. 3).

As a result, the signal waveform has a certain slope when the product is good (see figure (a)), and when it is contaminated (see figure (b)) or defective (see figure (c)). are respectively waveforms that change in the middle of the slope O. The once delayed signal d is applied to one terminal of the differential amplifier 6 and the delay circuit S. The delay circuit 5 applies a certain time delayed signal C1 to the other O terminal of the differential amplifier 6. Then, by taking the difference in the differential amplifier 6, a second O-delay separation is performed (see waveform f in FIG. 3). It can be seen from the delay differential of 02 degrees that there are different parts in the O signal waveforms for good products and defective products. The signal subjected to delay differentiation twice is further applied to one O terminal of the comparator 70. A negative reference level g is added to the other O terminal of the comparator 7 for comparison.
Value. The signal binarized by the comparator 7 becomes 1 pulse when the product is good, and 2 pulses when it is a defective product, as shown in the third diagram. ). Counter 9 &:
The count value is inputted and counted during one water period, and the counted value in the O counter 9 for each horizontal scan is stored in the memory 11. In order to simplify the 70@10 determination, the counter 9 is reset at the beginning of horizontal scanning, and the counter 9 counts the number of pulses per horizontal scanning line.

On the other hand, the comparator 8 compares the output f of the differential amplifier 60 with a positive reference level. The output t of the comparator 8, as shown in the iris 3g, is 2 pulses for a mourned item and 3 pulses or more for an undamaged item. This number of pulses is counted by the counter 10 and stored in the memory 12 in the same manner as described above. Memo for just one screen! After storing the number of pulses in Jll, 12, the judgment circuit 1
3 (for example, composed of a microcomputer), and if the result is that the tablet P is defective, a signal is given to the ejecting section 14, and the tablet P is ejected to the unnecessary article storage section.

There are several possible determination methods by the determination circuit 13, which will be listed below.

@1 (1) method is to check the number of pulses in memory 11,
The number of times the pulse is equal to or greater than the pulse is counted and compared with a set value, and if it is equal to or greater than the set value, it is determined to be defective. In the 20th method, the number of pulses in the memory 12 is checked, the number of times the number of pulses is 3 or more is counted, the counted value is compared with a set value, and when the number is equal to or higher than the set value, it is determined to be defective. The third method is to check the number of pulses in the memory 11, count 0 times when there are two or more pulses consecutively before and after each scanning line, and compare it with a set value to see if the counted value is greater than or equal to the set value. It is judged as defective at 0 o'clock. The fourth method is
The number of pulses in the memory 12 is checked, and the number of consecutive pulses of three or more before and after each scanning line is counted and compared with a set value, and when the counted value is greater than or equal to the set value, it is determined to be defective. In addition, the fifth method is to check the memory llo/< rus number,
This is a method in which 3 or more pulses are determined to be defective, and the 60th method is to check the number of pulses in the memory 120, and if 4 or more pulses are 0, it is determined to be defective. And how to judge these.

By appropriately combining methods, even minute defect signals can be reliably determined.

As described above, according to the present invention, a signal obtained by a TV camera or the like is differentiated twice, and the signal is binarized by comparing the positive level and the negative level, and the number of pulses for each horizontal scanning line is stored in memory. By storing the information in the image data, it is possible to reliably determine a defective part of a minute signal that has a two-dimensional spread.

In addition to the tablets described above, the present invention can also be applied to similar shaped caramels, chocolates, and other O-industrial products. Also, mandarin oranges.

It can also be applied to the appearance inspection of fragile objects such as apples.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram for explaining the binarization method of the inspection object, Fig. 92 is a block diagram showing an embodiment of the present invention, and Fig. 3 is a waveform diagram showing waveforms of various parts in Fig. 2. . Code explanation 1... Imaging device (television camera), 2.
・・・・・・Terminal circuit, 3, 5・・・・・・Delay circuit, 4
, 6... Differential amplifier circuit, 7, 8... Comparison circuit, 9, 10... Counting circuit, 11, 12...
...Memory, 13...Judgment tube path, 14.
...Discharge department, P ...Inspection object agent
Patent attorney Akio Namiki Agent Patent attorney Kiyoshi Matsuzaki

Claims (1)

[Claims] An imaging signal obtained by horizontally and vertically inspecting an object to be inspected by an imaging means, an oscillatory imaging signal obtained by oscillating the imaging signal, and O
A tenth differential amplification means for calculating the difference, an output signal of the wrinkle amplification means, a transparent output signal obtained by transmitting the # output signal, and oIll.
a 20@% increasing means for calculating the first and 20@% increase means;
a first and a twentieth binarizing means for comparing the O output from the differential amplification means with mutually different reference levels;
a comparison means, first and second counting means for counting the signals binarized by the j11 and j12 comparison means for each horizontal scan, and the first and second stitch count R;
1. An inspection device comprising first and twentieth storage means for storing otB forces, respectively, and determining whether or not the object to be inspected *10 is good or bad based on the contents of the first or second storage means O.