JPS6096088A - Defect detector of shaft symmetrical object - Google Patents

Abstract

PURPOSE:To allow detection of a defect of a shaft-symmetrical object at high speed and with a simple constitution by comparing signals following a symmetrical shaft of picture signals of the second frame and stored picture signals which are read reversely from a memory, and by detecting asymmetry by the defect. CONSTITUTION:This circuit is operated by two-time frame scanning of a picture signal of TV camera output which is obtained as video input. At the first scanning, the picture signal is made binary by an analogue comparator. At the second scanning, the picture signal is A/D converted by an A/D convertor 3, and inputted to an FIFO/LIFO4. The FIFO/LIFO4 has two modes. The FIFO/LIFO4 which is in a FIFO mode first becomes a LIFO mode and outputs reversely data before an address Xc, and therefore, these waveform data are compared with picture data which are outputted from the A/D convertor 3. When a shaft-symmetrical object has stains or deformation, the difference of the subtracted results becomes larger, and therefore, detection is possible by a digital comparator 7 through an integrator or adder 6 in accordance with necessity.

Description

[Detailed Description of the Invention] [Technical Field] The present invention provides a defect inspection method in which the entire object to be inspected is photographed by a TV camera, and the image signal of this TVi camera is processed to inspect the presence or absence of defects in the object to be inspected. An inspection device,
In particular, the present invention relates to a defect inspection apparatus NK for an axially symmetrical object, which inspects the presence or absence of defects in an axially symmetrical object as an object to be inspected.

[Background technology]

2. Description of the Related Art Conventionally, there is a pattern machining method as a method of thoroughly inspecting products of various shapes for defects using a TV camera. Is this male voice loud? This method memorizes all the patterns of good products and compares them pixel by pixel with the image of the product to be inspected for defects, but in reality, the reference pattern and the target pattern differ by just one pixel. Therefore, either rI
It is necessary to repeat the adjustment of fineness while changing the position of the II image, which has the disadvantage of increasing processing time.In addition, it is necessary to prepare a frame camera for two strokes, and the cost is high, making it impractical. In this case, processing with binary image 1 was the limit.

If we limit the object of the blind defect @ eclipse to an axially symmetric object, then by comparing around the axis of symmetry, reference 2 ~
Although there is no longer a need to prepare for a turn, the entire target pattern is memorized and the software sequentially calculates and compares the symmetrical addresses on both sides of the symmetrical axis, so there is still the problem of processing time. .

[Purpose of the invention]

The entire purpose of Zero-Hatsu-1 is to provide a complete defect inspection device for axially symmetrical objects that is capable of detecting defects in axially symmetrical objects at high speed with a simple configuration. [Disclosure of the Invention] (Example 1) Fig. 1 shows a monitor image when an axially symmetrical object is photographed with a TV camera. In the figure, the cross-hatched area is the background, and the level is sufficiently low (dark). Symmetry @ is located near the center of the screen as shown by the dashed line + -, and the axis-symmetric object that is the object to be inspected has a shape as shown by the hatched area and white area in the same figure, and is symmetrical in the horizontal direction. , the rotational deviation is assumed to be negligibly small. FIG. 2 shows the configuration of a first embodiment of the present invention. This circuit is based on two frame scans of the image signal of the TV camera output, which is obtained as a "video input". During the first scanning, the image signal is binarized by the analog comparator [11] as shown in FIG. At this time, since the background is sufficiently dark, the slice level Kl is set at a voltage level at which the entire object becomes white % I 11 and the background becomes black 10 I.

1' control section (2) controls 1 in 1 horizontal period.
Addressing the change point from 0' to '1' and 11'
Detect the address XB of the changing point from Relatives have been. Next, in the second scanning of the image body No. 18, the image signal is A/D converted by the A/D converter (3) and input to the FIFO/LIFO 141. The PI F'O/L I FO 141 has two motes, and when it is a FIFO mode, the data that enters first comes out first, so it functions similarly to a plurality of shift registers. Also, in LIFO and 7-rd, the data input last is output first. Therefore, F I FO'e-
When it is set, it is a buffer for data flow, and LIFO
E-Do VL:, 17J#) The contents of the buffer are read in reverse from the moment the change occurs. This switching tie jig is set to the symmetrical axis address X from the timing control section (2).

Then, the FIFO that was originally in the FIFO'e-do
/L I FO141 goes into LIFO mode and outputs the data of 11J after the start status in reverse, so if you compare this waveform data with the image data output from the A/D converter (3), you can find defects in the axially symmetrical object. When there is no difference and the images themselves are symmetrical, the waveforms are the same, and even if the latter data is subtracted from the former data using the subtracter (6), the value is only about that of noise. However, if an axially symmetrical object has defects such as dirt or deformation, the difference in results will be large, so it can be detected by a digital comparator (7) via an integrator (6) or an adder as necessary. becomes. This judgment period 1IIi starts from the address XO and x(, -XB(or XA-
XO), and the timing control unit t21 specifies (gates) the period.

(Practical Example 2) FIG. 4 shows the configuration of the second embodiment of the present invention, which is either the one of the first embodiment described above or the FI
FO/L I From the output waveform data of FO+41, A/
The image data output from the D converter (3) is subtracted, and the digital comparison heat (7) is used to compare whether or not the subtracted value exceeds the set value. The embodiment is equipped with a total correlator (8) that correlates the output waveform data of FIFO/1:IF0 (4) with the image data output from the A/D converter (3), and this correlator (SLTI) The determination is made using a digital ratio secondometer (7).The correlator (8) is constructed, for example, by a correlation IC having a volume II and a relative as shown in the block diagram of Fig. 5. A/Df converter (3) output (i.e. F I FO
/L I FOi + 1 output), the number of correlator units 0 = n corresponds to the number of pits &n, and one correlation maxim for each hit is made, and the number of SUMI~n, which is one less than the number of pits n, makes one pit. The structure is such that the output of the correlator unit is sensed by moving it to the left as you go to the lower stage.
The output of UMn will be obtained as the correlator)8) output.

[Effect of departure]

Since the present invention is configured as described above, the phase of the axis of symmetry of the axially symmetrical object is measured in the first frame, and a highly viscous positioning method is not required. In addition to the sound effect that simplifies the defect horizontal placement operation,
Regardless of the shape of the object, as long as the object is axially symmetrical, it has the effect of detecting defects in any shape with the same processing.Moreover, the configuration is simple and the image memory is stable.
This has the effect of achieving cost reduction, and also has the effect of achieving 2
Since processing can be performed within the scanning time of a frame, it has the effect of enabling convex speed processing.

[Brief explanation of the drawing]

! -5' Fig. 1 is a monitor drawing of an axially symmetrical object according to an embodiment of the present invention, Fig. 2 is a block circuit diagram of the same as the above, and Fig. 3 is a t-monitor drawing of the same as the above binarized axially symmetrical object. Figure 4 is a block circuit diagram of an embodiment of the f4JJ2 of KV1J, Figure 5.
The figure is an internal block diagram of the above correlator, and (4) is F
I FO/L I FOT6ru. Agent Patent Attorney Ishi 1) Ai Shichi

Claims (1)

[Claims] A TV camera for photographing an axially symmetrical object; means for measuring the position of the axis of symmetry of the axially symmetrical object in the first frame of the image signal output from the TV camera; Looking down at the memory where the image signal is stored in the casing at the axis of symmetry, compare the signal of the image signal of the second frame after the axis of symmetry with the stored image signal read out from the memory in reverse. A defect inspection device for an axially symmetrical object, which is characterized in that it detects asymmetry due to defects by detecting asymmetry due to defects. 12+ image false signal is A/D converted and input FI FO
/LIFO constitutes a memory, stores image data in FIFO, and reads out the image data in LIFO according to the output of the address counter in which the axis of symmetry position is set, and stores the read out memory. Claim 1rA is characterized in that the difference between the image data and the image data obtained by A/D converting the image signal is detected, and the difference is compared with a preset value. Defect inspection equipment for axially symmetrical objects. (3) Asymmetry due to defects is detected by calculating the correlation between the signal after the axis of symmetry of the image signal of the second frame and the stored image signal read out in reverse from the above-mentioned grid. A defect inspection device for an axially symmetrical object according to claim 1.