JPS6266144A - Surface defect inspection device - Google Patents

Abstract

PURPOSE:To reduce the storage capacity by starting a video recorder between a field in which existence of a defect is detected automatically, and the next field, and recording it in said recorder by being delayed by one field therefrom. CONSTITUTION:A differential signal from an image processing circuit 13 is inputted to a controlling circuit 20, and in case when a part exceeding a threshold value exists, a video tape recorder (VTR) signal is outputted between the field concerned and the next field, and a VTR 18 is operated by a two field portion. The circuit 20 executes a control of a read-out address of a video memory 16, and the field in which a defect has existed is recorded in the VTR by being delayed by two fields. By a signal for showing a moving extent of a strip 10 from a pulse generator 21, the circuit 20 gives this position information to a superimposer 17 and records it in the VTR. In this way, only a picture having a defect is recorded in the VTR, and in case when the defect has been brought to an image pickup simultaneously by both television cameras, an image of two fields is recorded in a tape length of a three field portion, and the storage capacity can be curtailed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for optically inspecting the surface of a moving object, such as a fully bent strip during a manufacturing process, for defects.

[Prior art and problems to be solved by the invention] An apparatus for optically inspecting a metal strip for surface defects is to take a still image of the metal strip using a two-dimensional imaging device such as a television camera, and then capture the image. Some devices use processing technology to inspect the presence or absence of defects, and if defects exist, they are classified according to their importance. However, such a device has to process a huge amount of data, which makes the device extremely costly and expensive.

A device has also been developed that records still images on a magnetic sheet, etc., and visually observes the reproduced image to classify defects. Requires capacity.

c. Means for Solving Problems] The present invention has been made to solve such problems, and there are defects in video signals of still images taken by each of a plurality of two-dimensional imaging devices. A still image is automatically detected and one field of this still image is stored in a video memory that serves as a buffer. It is an object of the present invention to provide a surface defect inspection device which starts up a recorder and records on it with a delay of one field, thereby reducing the required recording capacity.

A surface defect inspection apparatus according to the present invention is an apparatus for optically inspecting surface defects of a moving object, and includes a plurality of 2:1 interlaced two-dimensional imaging devices for capturing still images of the surface of the object. , means for detecting the presence or absence of a defect by alternately inputting one field of the video signal from each two-dimensional imaging device, and having a capacity of at least two fields, and storing the video signal or a signal processed therefrom. a video memory, a video recorder, an imaging position detector of said object, means for driving the video recorder if the presence of a defect is detected, and a video memory corresponding to the field in which the presence of a defect is detected; The present invention is characterized by comprising means for recording the signal in association with the imaging position of the object with a delay of one field after the start of driving of the video recorder.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below based on drawings showing embodiments thereof.

FIG. 1 is a schematic block diagram showing the overall configuration of a surface defect inspection apparatus according to the present invention.

The strip 10 to be inspected is moved in its longitudinal direction, and a 2=1 interlaced TV camera is placed directly above the movement range, and the width direction of the strip 10 is moved by 1/1. Two fields of view each constitute an imaging field of view. Video signals of the captured images are alternately input from the television camera controls 12a and 12b to the ζ image processing circuit 13 via the switcher 12.

The image processing circuit 13 includes a circuit for differentiating a video signal,
The differential signal serves as the control center of the imaging recording system of the device of the present invention;
While being input to the til control device 20, ■ frame (2
The data is input to a video memory 16 having a capacity of (field).

The control device 20 generates a differential signal of the manually inputted video signal.
If this exceeds a predetermined darkness value, correspond to the captured image J
“It is determined that there is a defect in the part.

The presence or absence of such defects is determined on a field-by-field basis.

The contents of the video memory 16 are recorded by the video tape recorder 18 as will be described later.
The image position of the strip 10 taken by the television cameras lla, 11b, in other words, is recorded on a recording medium, that is, a videotape, superimposed on characters indicating the position of the defect. 17 is a superimposer for superimposing the characters and the image stored in the video memory 16.

A signal input to the video tape recorder 18 for recording is displayed on the monitor 19, and an image reproduced by the video tape recorder 18 is also displayed on the monitor 19.

14 is a television camera 11 . of the strip 10 for still image capture. A strobe light source is provided diagonally above the imaging area to illuminate the imaging area by a, llb, and is powered by a strobe power source 15 that adjusts the amount of light by adjusting the voltage applied to the strobe light source 14. It has become.

A pulse generator 21 is disposed below the movement range of the strip 10, and is rotated by a touch roller that rolls into contact with the strip 10, and outputs pulses of an amount corresponding to the amount of movement of the strip 10. This output pulse is the control circuit 2
It is input to 0.

Reference numeral 22 denotes an editing and aggregation device using a personal computer system, and a computer main body 22a.

It consists of a monitor 22b, a keyboard 22c, a printer 22d, and a floppy disk drive 22e, and when an operator monitors the monitor 30 to evaluate defects and classify them, he inputs a symbol corresponding to the classification from the keyboard 22c.

The computer main body 22a combines the input information from the keyboard 22c and the information given from the control circuit 20 side, that is, the recording position information of the corresponding part on the video tape and the imaging position information of the strip IO, and outputs this information to the floppy disk drive 22e. The information is recorded on a floppy disk, displayed on the monitor 22b by reproduction, or recorded on the printer 22d.

The editing and tabulation device 22 tabulates the defect by Ifi category based on such input information, and displays this on the monitor 22b or outputs it on the printer 22d.

Next, imaging control by the control circuit 20 will be explained. The control circuit 20 issues a trigger signal for the strobe power source 15 at appropriate intervals as shown in FIG. 2(A). The strobe light source 14 is thereby driven.

The control circuit 20 provides a vertical synchronization signal to the television camera control 12a in synchronization with this trigger signal, and further provides a vertical synchronization signal to the television camera control 12b after l field delay. This allows the TV camera lLa
, llb will capture a still image by light emission from the strobe light source 14. The light emitting time of the strobe light source is set so that it does not interfere with the imaging of one frame, and the light emission interval is set so that it does not interfere with the inspection of the entire surface of the moving strip 10.

The control circuit 20 includes each television camera control 12a.

12b controls the switch 12 to connect the television camera controller 12a or 12b to the image processing circuit 13 during a field in which the television camera controller 12b outputs a video signal.

The image processing circuit 13 includes a television camera control 12a,
The video signal of the still captured image sequentially inputted from 12b is differentiated. FIG. 2(b) shows this differentiated signal, and the defect-existing portion has a large amplitude. This differential signal is the video memory 1
6 [Figure 2 (c)]. Note that when this differential signal is read out and displayed on the monitor 19, an image is displayed with the bottom portion emphasized.

On the other hand, the differential signal is input to the control circuit 20, and it is checked whether there is a portion in the differential signal for one field that exceeds a predetermined threshold value. And 3 on the left side of Figure 2
If there is a part that exceeds the dark value (shown by the broken line in Figure 2 (b)), as in the case of two signals, the video tape recorder activation signal VS C2 is sent between the corresponding field and the next field.
Figure (d)] is output. In response to this, the video tape recorder operates two fields per day. If there are defects in the captured images of the two television cameras 11a and 1lbn, the activation signal vS will be input for two consecutive fields as shown in FIG. The camera operates for three fields without stopping.On the other hand, if the defect exists only in the image of one TV camera, for example, lla, it will operate for two fields as shown in the center of Figure 2. It runs for a minute and then stops.

The control circuit 20 controls successive addresses of the video memory 16, and records the differential signal of the frozen video signal in the video memory 16 from a timing delayed by a time corresponding to one field after the start of driving of the video tape recorder 18. [Figure 2 (E)] In other words, the field in which the defect exists is recorded on the videotape with a total delay of two fields. Also both TV cameras
If a defect is detected in images a and llb, two fields are continuously recorded, and in the end, two fields are continuously recorded in a three-field recording space on the videotape. Note that the reason why recording is not performed in one field immediately after startup is because the running of the tape is unstable.

On the other hand, since the control circuit 20 receives a signal representing the amount of movement of the strip IO from the pulse generator 21,
Strip 1 from the start of inspection to the point when a defect is detected
The control circuit 20 can specify the amount of movement of 0, in other words, the imaging position.

The control circuit 20 supplies this position information to the superimposer 17 to record it on a videotape. In this way, only the defective screen will be recorded on the videotape, and if the defect is captured simultaneously by both television cameras (which is often the case), the tape length will be reduced to three fields. 2F/L/F images will be recorded,
Recording capacity can be saved and long objects can be inspected easily. However, in the past, in such cases, one screen (l frame) of one television camera was recorded in three fields, resulting in a total of six fields.

And as in the embodiment, a personal computer system 2
If the classification and position of the defect are input in step 2, the information necessary for cleaning, cutting, etc. can be immediately processed and obtained.

When playing back a videotape, the signal of one field is played back twice and combined into one frame for display in order to improve the image quality.

In addition, in the above embodiment, two television cameras were installed to inspect only the top surface, but if it is necessary to inspect the bottom surface as well, it is necessary to install two television cameras and a light source on the bottom side as well. , all that is required is to sequentially switch the controls for a total of four television cameras. In this case, when a screen with defects is captured simultaneously by all cameras, as is clear from the above, four fields of images are recorded on the tape length of five fields, and Even higher density recording becomes possible.

Further, in the above embodiment, defects were detected by analog differentiation of the video signal, but the present invention is not limited to this, and digital differentiation or other methods may be used.

Further, the signal to be stored in the video memory 1G may be the video signal itself instead of the differential signal of the video signal as described above. Which one to use depends on the state of the surface image of the inspection object, and it is preferable to record a signal that allows defects to be easily recognized during reproduction and visual inspection.

Furthermore, in order to obtain a still image, the television camera 11 may be provided with a high-speed shutter instead of using the strobe light source 14 described above.

Furthermore, the means for recording the contents of the video memory is not limited to a video tape recorder, but may be other magnetic or optical media.

〔effect〕

As described above, in the case of the present invention, since the captured image is recorded for one field, the substantial recording density is improved, and if there are consecutive images with defects, they can be continuously recorded without stopping the recording medium. The present invention has excellent effects such as being able to record data and making effective use of the recording medium.

[Brief explanation of drawings]

FIG. 1 is a schematic block diagram of the apparatus of the present invention, and FIG. 2 is a time chart 1 for explaining its operation.

Claims (1)

[Claims] 1. An apparatus for optically inspecting a moving object for surface defects, comprising: a plurality of 2:1 interlaced two-dimensional imaging devices each for capturing still images of the surface of the object; means for detecting the presence or absence of a defect by alternately inputting one field of a video signal from a dimensional imaging device; and a video memory having a capacity of at least two fields and storing the video signal or a signal obtained by processing the video signal. , a video recorder; an imaging position detector for said object; means for driving the video recorder when the presence of a defect is detected; After the recorder starts driving 1
1. A surface defect inspection device comprising: means for recording in association with an imaging position of an object with a delay corresponding to a field time. 2. The surface defect inspection apparatus according to claim 1, wherein the means for detecting the presence or absence of a defect includes a video signal differentiation circuit. 3. The surface defect inspection apparatus according to claim 1 or 2, wherein the video memory stores a differential signal of a video signal.