JPS5815041B2 - Inspection method and equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method and apparatus for inspecting the shape of an object, and in particular, the present invention provides a method and apparatus for inspecting the shape of an object. The present invention relates to a method and apparatus for inspecting objects that can be accurately inspected.

In a conventional inspection device for this type of object, first, for example, the first
As shown in the figure, a standard object, that is, a standard object 1, is placed on an inspection table T, a light source 2 irradiates it with light, a television camera 3 takes an image of this standard object 1, and the image signal from it is captured. ,
It is supplied to an image signal processing device or circuit 4 having an A-D (analog-digital) converter 41, an image signal feature extractor or circuit 42, etc. for processing, and the output information or signal therefrom is converted into a standard information signal. For example, computer 43
to be memorized.

Next, place the object to be inspected at the position of the standard body 1 on the inspection table T (
Therefore, this object to be inspected is also indicated by reference numeral 1), is imaged by the television camera 3, the image signal is processed in the same way by the image signal processing circuit 4, and the output information from this is sent to the computer 43, where it is It is compared with previously stored information on the standard body to check whether the object to be inspected is the same as the standard body, that is, whether it is good or bad.

In such a conventional inspection device, through the inspection of each object to be inspected, the amount of light from the light source 2 irradiating the object 1 to be inspected is greater than that from the light source 2 irradiating the standard object when the standard object is imaged. The image signal from the television camera 3 obtained by imaging the object to be inspected 1 may be different from the amount of light of the object to be inspected, or furthermore, due to the drift of the electric circuit system of the television camera, etc. Even if the image signal is the same as the standard object, it will be different from the image signal of the standard object, so the two will be determined to be different.
Misjudgment may occur.

However, as the light source 2 changes over time and the ambient light around the object to be inspected 1 changes, the amount of light hitting the object to be inspected 1 usually changes to an extent that cannot be ignored.

Furthermore, drift often occurs in electrical circuit systems such as cameras.

Therefore, depending on the conventional device, the above-mentioned erroneous judgment often occurs, and this type of device cannot avoid a serious drawback.

SUMMARY OF THE INVENTION Accordingly, the main object of the present invention is to provide a method and apparatus for inspecting objects, which eliminates the above-mentioned conventional drawbacks.

Another object of the present invention is to change the amount of light from the light source for each inspection of each object to be inspected relative to the amount of light when imaging the standard object; Even if the ambient light of the object changes, or even if there is temperature change or drift due to other causes in the electrical circuit system of the camera or related amplifier, all of these can be automatically and easily corrected. Correctly correct
It is an object of the present invention to provide an inexpensive method and apparatus for inspecting objects that enable precise inspection.

The inspection method according to the present invention is characterized in that, in the method of inspecting an object by processing an image pickup body and image signals from the image pickup body, an inspection method is provided within the field of view of the standard body and the object to be inspected of the image pickup body. A calibration body that serves as a reference for the conditions is arranged, the calibration body and the standard body or the object to be inspected are simultaneously imaged by the imaging body, and a signal corresponding to the calibration body is detected from among the imaging signals from the imaging body. However, the present invention resides in that the image signal from the imaging body is corrected using the detection signal.

Further, the inspection apparatus according to the present invention is characterized by an image pickup object, an A-reverse converter for processing image signals from the image pickup object, a feature extraction circuit, a computer, etc.

In an inspection apparatus that inspects an object, a calibration body serving as a reference for inspection conditions is placed within the field of view of the standard body of the imaging body and the object to be inspected, and Imaging the calibration body and the standard body or the object to be inspected by the imaging body at the same time;

supplying an image signal from the image pickup body to a calibration signal forming circuit;
As a result, a signal corresponding to the calibration object among the image signals is detected, and the detection signal and the image signal are supplied to a correction circuit, where the image signal from the image pickup object is corrected using the detection signal. Na.

It depends on what you did.

-f11 of the present invention will be explained below with reference to FIGS. 2 to 5.

In addition, in FIGS. 2 to 5, the same reference numerals as in FIG. 1 indicate the same elements.

In the present invention, when the standard body 1 is imaged by an imaging body such as the television camera 3, the television camera 3
In the example shown in FIG. 2, a calibration body 5 such as a white paper is placed near the standard body 1 on the stand T, and this calibration body 5 is used as a television screen in later inspections. This is used as a reference for the brightness of the field of view of camera 3.

When the calibration body 5 and the standard body 1 are imaged by the television camera 3, the imaged pattern on the screen S of the television camera 3 becomes as shown in FIG. 3, for example.

・In 5, 1' is an image of the standard body 1, and 5' is an image of the calibration body 5.

Further, the image signal from the television camera 3 at this time has a waveform such as the solid curve A in FIG. 4, for example.

In the waveform diagram of FIG. 4, 1" and 5" on the horizontal axis correspond to approximately the center positions of the image 1' of the standard body 1 and the image 5' of the calibration body 5, respectively, and A1 and B1 are , images 1' and 5 respectively
′ levels are shown respectively.

An image signal such as the solid line curve A in FIG. 4 from the television camera 3 is processed by the image signal processing device 4 in the same manner as before, and stored in the computer 43 as a reference or standard information signal for subsequent examinations. .

In the inspection of the object to be inspected according to the present invention, the calibration body 5 is
Place the standard body 1 under the same conditions as when the image was taken, place the object to be inspected in the same position as the standard body 1 (therefore, the object to be inspected is also indicated by reference numeral 1 in the figure), and place the object to be inspected in place of the standard body 1. 3, the calibration body 5 and the object to be inspected 1 are simultaneously photographed (imaged).

Therefore, the image on the screen S of the television camera 3 is exactly the same as shown in FIG.

In this case, the object to be inspected 1 and the standard body 1 are the same, the brightness within the field of view of the television camera 3 is the same as when the standard body was imaged, and the functions of the electric circuit system of the camera 3 etc. If both are the same, the image signal from the camera 3 will have the waveform of the solid curve A in FIG. 4, so there will be no problem of misjudgment during inspection by the computer 43.

However, as a practical matter, as mentioned above, due to changes in the amount of light from the light source 2, changes in the function of the electric circuit system such as the camera 3 (increased drift), etc., even if the object to be inspected is the same as the standard object, Even if the images are taken at the same location, the image signal from the camera 3 will, for example, follow the dotted line curve B in Figure 4.
As shown, the image signal A is different from the image signal A obtained when the standard body is photographed.

Therefore, if this image signal B is directly inspected by the computer 43 via the 5-image signal processing device 4, the object to be inspected will be determined to be defective.

An example of the image signal processing device 4 of the present invention that can avoid erroneous determination in such a case will be explained in detail with reference to FIG. 5.

In the example of the present invention shown in FIG. 5, the output image signal of the camera 3 is supplied to the A-D converter 41 as in the conventional case, and a calibration signal is obtained from the signal corresponding to the calibration body 5. It is also supplied to a calibration signal forming circuit 44 for detecting and forming.

A digital image signal from the A-D converter 41 and a calibration signal corresponding to, for example, the level of the image 5' of the calibration body 5 from the calibration signal forming circuit 44 are supplied to the correction circuit 45.

This correction circuit 45 corrects the digital image signal from the A-D converter 41 using a calibration signal from the calibration signal forming circuit 44 as follows.

That is, the image signal when the standard body was photographed was as shown by the solid line curve A in FIG. 4, and the levels of the image signals corresponding to the standard body 1 and the calibration body 5 were A1 and B1, respectively. However, due to the above-mentioned reasons, the image signal when the inspected object 1, which is the same as the standard object, is photographed becomes like the dotted line curve B in FIG. 4, and the image signal corresponding to the inspected object 1 and the calibration object 5. have changed to A2 and B2, respectively, so this level change is returned to the level of solid curve A, that is, level B2, to level B1, and the entire image signal B is returned to image signal A (in this case, level A2 is returned to level A1: the correction circuit 45 performs the correction.

Therefore, the output of the correction circuit 45 serves to make the conditions when photographing the object to be inspected 1 the same as the conditions when photographing the standard body 1.

In the example of FIG. 5 of the present invention, the output of the correction circuit 45 is supplied to the feature extraction circuit 42, and the output information signal is compared and inspected by the computer 43 with the information signal of the standard body.
When the same object to be inspected as the standard body is photographed, even if the image signal differs from the image signal A of the standard body as shown by curve B in Figure 4 due to the reasons mentioned above, the former is not calibrated. Since it is made to be the same as the latter by the action of the signal forming circuit 44 and the correction circuit 45, it can be determined that the two are the same.

The inspection method and apparatus according to the present invention are applicable only when the object to be inspected is truly different from the standard object (in this case, of course, the image signal itself corresponding to the object to be inspected is different from that of the standard object). ), the object to be inspected is determined to be rejected, and unlike the conventional apparatus described above, there is no erroneous determination caused by something other than the object to be inspected.In addition, the example of the present invention shown in FIG. 45 A-D
This is a case where the correction circuit 45 is provided after the converter 41.
The connection position does not need to be limited to the downstream stage of the A-D converter, and may be at any other position.

FIG. 6 is a block diagram showing the main part of another example of the present invention, that is, another example of the image signal processing device 4.
The same reference numerals as in the figures indicate the same elements.

For the first time, in the example of the present invention shown in FIG.
The output signal of
In step 5, the image signal from the camera 3 is normalized.

That is, an image signal is created from which influences such as changes in the amount of light irradiated to the calibration body 5 and drifts of the electric circuit system of the camera 3, etc. are removed, and this signal is sent to the 'A-D converter 41, The feature extraction circuit 42 and computer 43 process and test the data.

Therefore, with this example of the invention, the conventional drawbacks can also be avoided.

As described above, according to the present invention, the image signal corresponding to the object to be inspected from the camera may be caused by changes in the amount of light to the object to be inspected or the electric circuit system of the camera, etc. Simply place the calibration object within the camera's field of view for the standard object or object to be inspected, even if the conditions have changed from those at the time of the test.
Based on the imaging signal from the camera corresponding to this calibration body,
A calibration signal is generated by a calibration signal forming circuit, and using this signal, the above-mentioned change in the image signal is automatically corrected by correcting it by a correction circuit before comparing and processing the imaging signal from the camera with a computer, etc. , it is possible to avoid misjudgment due to the causes mentioned above.

Therefore, in the present invention, there is no need to use an expensive light source with little variation in light intensity, and there is no need to provide strict light protection equipment to prevent changes in the light intensity from the light source to the object to be inspected. This has the advantage of significantly reducing the cost of this type of device and improving accuracy, since fewer and more expensive cameras are not required.

In the illustrated example, the calibration body 5 is placed on a part of the table T, but the position of the calibration body 5 is such that it does not interfere with the imaging of the standard body or the object to be inspected within the field of view of the camera 3. Any position is acceptable as long as it remains unchanged relative to the standard object and the object to be inspected during imaging.

Furthermore, the calibrator 5 does not have to be limited to white paper; it may be gray, yellow, etc., as long as the above-mentioned purpose can be achieved, and there is no need for any special restrictions on the material; It is clear that anything can be used as long as it can be kept unchanged, and there are no particular limitations on its shape.

Furthermore, although in the illustrated example the correction is performed by the hardware of the apparatus, similar corrections can also be performed by computer software.

[Brief explanation of drawings]

Figure 1 is a schematic block diagram of an example of a conventional inspection device.
FIG. 2 is a systematic block diagram of an example of the inspection device of the present invention, FIG. 3 is a front view of the screen of the television camera of the present invention, and FIG. 4 is a waveform diagram showing image signals of the television camera of the present invention. FIG. 5 is a block diagram of the main parts of the system diagram of the present invention shown in FIG. 2, and FIG. 6 is a block diagram of the main parts of another example of the invention. In the figure, 1 is a standard body or an object to be inspected, 2 is a light source, 3 is a television camera, 4 is an image signal processing device, 5 is a calibration body, 4
1 is an A-D converter, 42 is a feature extraction circuit, 43 is a computer, 44 is a calibration signal forming circuit, 45 is a correction circuit,
S is the camera screen, 1' is the image of the object to be inspected, and 5
′ indicates the image of the calibration body, respectively.

Claims (1)

[Claims] 1. In a method of inspecting an object by processing an imaging body and image signals from it, a reference object for the inspection conditions is provided within the field of view of the standard body and the object to be inspected of the imaging body. A calibration body is arranged, the calibration body and the standard body or the object to be inspected are simultaneously imaged by the imaging body, a signal corresponding to the calibration body is detected from among the imaging signals from the imaging body, and the detection signal is detected. An inspection method characterized in that the image signal from the imaging body is corrected by. 2. In an inspection apparatus for inspecting an object, which includes an image pickup body and an image signal processing device having an A-ray converter, a feature extraction circuit, a computer, etc. for processing image signals from the image pickup body, the image pickup body A calibration body, which serves as a reference for the inspection conditions, is placed within the field of view for the standard body and the object to be inspected, and the calibration body and the standard body or the object to be inspected are simultaneously imaged by the image pickup body, and the image from the image pickup body is An image signal is supplied to a calibration signal forming circuit, which detects a signal corresponding to the calibration object among the image signals, and the detection signal and the image signal are supplied to a correction circuit, where the signal from the image pickup object is detected. An inspection device characterized in that an image signal is corrected using the detection signal.