JPS63225111A - Visual inspection - Google Patents

Abstract

PURPOSE:To enable a stable visual inspection to be achieved without the accuracy of judging the adequacy of product being affected by inducers by sequentially updating the reference data on the basis of the measured data of a product to be inspected which is judged as acceptive. CONSTITUTION:The initial reference data A of the images taken from products W-Wn to be inspected which are fed into an inspection station are set in advance. The data A and the measured data A1-An of the products W-Wn, respectively, are compared with each other and whether the products W-Wn are acceptive is judged. The data A are corrected B on the basis of the data A1-An judged to be acceptive. Reference data B thus corrected and the measured data A1-An of the products to be inspected are compared with each other and whether the products being inspected are acceptive or rejective is judged. Further, the data B are sequentially updated at least on the basis of the measured data of the products to be inspected that are judged as rejective. Thus, generated factors can be absorbed by making the data B follow up the generation of the factors that bring about the judgment of the acceptives or rejectives and a stable visual inspection can be performed without being affected by the generation of factors inducing the incorrect judgment on acceptives or rejectives.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to an inspection method using a visual device.

(Prior art) In an inspection method that uses a visual device to determine the acceptability of an object to be inspected, the captured image data of the object to be inspected is compared with preset reference data, and the reference data and allowable tolerances are compared. A determination method is adopted in which if the measured data is included in the range set by the above, it is determined to be a non-defective product, and if it is not, it is determined to be a defective product.

(Problems to be solved by the invention) However, changes in the optical environment at the place where visual inspection is performed,
Image data of a good inspection object may shift outside the above-mentioned tolerance range due to changes in the amount of illumination light due to voltage fluctuations or changes in the state of the inspection object, etc., but the above-mentioned tolerance range remains unchanged over time. With this setting method, it is not possible to deal with the occurrence of factors that induce erroneous pass/fail judgments, and stable inspection cannot be expected.

Structure of the Invention (Means for Solving the Problems) Therefore, in the present invention, from the viewpoint of making the reference data follow the occurrence of factors that induce the above-mentioned erroneous pass/fail judgments, the present invention provides inspection objects that are sequentially sent to predetermined inspection stations. The quality of the test object is determined based on the comparison between the preset initial reference data of the captured image of the object and the measurement data of the test object. The initial reference data is corrected based on the corrected standard data and the measured data of the test object is determined based on the comparison, and the quality of the test object is determined based on at least the measurement data of the test object that has been determined to be non-defective. The standard data will be updated sequentially.

(Function) In other words, if the data of the captured image of the inspection object is area, for example, the measurement area specified by the bright/dark boundary changes for the same inspection object due to changes in the optical environment such as disturbance light fluctuations, but the measurement area If the measured area is determined to be within an allowable range by comparison with a preset initial reference area, a new reference area is set from at least the measured areas within these allowable ranges. This reference area update is performed over time based on new measurement areas sequentially obtained from at least non-defective inspection objects, and the reference area to which the measurement area of the inspection object is compared is subject to the occurrence of factors that may induce erroneous pass/fail judgments. Follow.

Therefore, the accuracy of pass/fail judgment is not affected by the above-mentioned triggering factors, and stable visual inspection can be achieved.

(Example) Hereinafter, an example embodying the present invention will be described based on the drawings.

As shown in FIG. 1, the objects W to be inspected that are aligned and held on the conveyor 1 are sequentially sent to an inspection station S set below the camera 2 installation position by the intermittent feeding of the conveyor 1. The inspection object W sent to the inspection station S is irradiated by a lamp 3 installed near the side of the camera 2, and this reflected light is captured by the camera 2.

The image signal from the camera 2 is input to the comparison/judgment device C,
The comparison/judgment device C determines the inspection target W based on the input image signal.
A predetermined signal is output if the product is determined to be defective.

The comparison/judgment device C includes an image data storage means for storing an image signal as binary data, an image data processing means for specifying the planar area of the inspection object W from the stored image data, and a preset inspection Initial reference area A of object W
and storage means for storing the allowable tolerance ±Δ, and the inspection object W.
a comparison determination means for determining pass/fail by comparing the measured area with a reference area, a counting means for counting the number of times of non-defective determination, an area addition means for adding the measured area of the inspection object W determined as non-defective, and an addition area. and updating means that rewrites and updates the reference area stored in the storage means to the divided area, and in the case of a defect, a predetermined signal is output from the comparison and determination means.

The quality determination using the visual device in this embodiment is performed based on the flowchart shown in FIG. 3, and its operation will be explained below.

Now, the inspection object W sent to the inspection station S
A plane image of 1 is captured from camera 2, and 2 of this image is
The value data is stored in the comparison bag WC. A plane area A1 of the inspection object W1, which is specified by the boundary between a bright area formed by reflection on the inspection object W1 and another dark area, is extracted and specified based on the processing of the image data, and this specified measurement area A1 As shown in Figure 2, the initial reference area A and the tolerance ±
It is determined whether or not it is within the initial tolerance range [A-Δ, A+Δ] set from Δ. Comparison and determination device C has a measurement area AI that is within the initial tolerance range [A-Δ.

A + Δ], a defective product judgment signal is output, and as shown in Figure 2, if the measurement area A1 indicated by the measurement display point al is within the initial tolerance range [A - Δ, A + Δ] In addition to counting the number of non-defective product determinations, the reversal area A1 is added.

A similar comparison is made for the inspection object W2 that is sent into the inspection station S following the inspection object W1, and the measurement area A2 indicated by the measurement display point a2 falls within the initial tolerance range [
A-Δ, A+Δ], the number of good product judgments is 2.
is counted, and the measurement area A2 becomes the measurement area A1.
will be added to.

Such a comparison judgment based on the initial standard area A is performed until the number of non-defective judgments reaches a preset value n, and when the number of non-defective judgments reaches n, the inspection target W which has been judged non-defective
1, W2...Wn measurement areas At, A2...An
The added area Σ(n) is divided by the number of good product determinations n. The divided area Σ(n)/n=B calculated and set in this way is adopted as the reference area instead of the initial reference area A, and the reference area for setting the tolerance range is changed from the initial reference area A to the reference area. Updated.

Thereafter, the measured area of the inspection object W that has been newly determined to be non-defective is added up by n pieces in the same way as above, and the area obtained by this addition is divided by n, and the reference area and tolerance range are shown in Figure 2. It will be updated sequentially.

Such updating of the reference area is performed in response to fluctuation factors such as changes in the optical environment that lead to changes in the measurement area of the same inspection object W, changes in the amount of illumination light due to voltage fluctuations, and changes in the environment such as temperature and humidity. The occurrence of these fluctuation factors is absorbed by updating the reference area, and the quality determination of the inspection object W is always performed with constant accuracy. Therefore, even if a variable factor such as a change in the optical environment or a change in the amount of illumination due to a voltage change occurs that causes a change in the measurement area of the same inspection object W, the quality judgment of the inspection object W is influenced by the triggering factor. A stable visual inspection can be achieved.

The present invention is, of course, not limited to the above-mentioned embodiments. For example, instead of the reference area updating method using the arithmetic mean in the above-described embodiments, a reference area updating method using a geometric mean may be adopted, or an inspection sent to an inspection station may be adopted. Instead of the method of the above embodiment in which the reference area is updated in units of groups of a predetermined number of objects, an updating method shown in the flowchart of FIG. 4 is also possible. In this method, the initial reference area is used until the areas of n non-defective inspection objects W are added up, and after this, the measured area of the inspection object W that was judged to be non-defective is compared with the updated reference area and is used to add up the area of the n non-defective inspection objects W. The first measured area within the addition area is replaced by n.
The standard area is updated by dividing by . Further, it is also possible to use the reference area together with the measurement area as one element for setting a new reference area. Alternatively, in visual inspection of a predetermined area within the inspection object, the visual inspection method of the present invention may be applied to fluctuations in the feeding position of the inspection object.

Effects of the Invention As detailed above, the present invention determines the quality of the object to be inspected based on the comparison between the reference data of the captured image of the object and the measured data of the object, and also determines whether the object is at least determined to be non-defective. Since the reference data is updated sequentially based on the measurement data of the object to be inspected, it is possible to absorb the factors that occur by following the reference data even if the factors that cause an incorrect pass/fail judgment occur. This provides an excellent effect in that a stable visual inspection can be performed without being influenced by the occurrence of factors that induce judgment.

[Brief explanation of drawings]

The drawings show an embodiment embodying the present invention, in which Fig. 1 is a perspective view of the vicinity of the inspection station, Fig. 2 is a graph showing the displacement of the reference area, Fig. 3 is a flowchart of comparison and judgment, and Fig. 4 is a A separate flowchart. Conveyor 1, camera 2, inspection station S, inspection objects W1, W2...Wn, comparison/judgment device C1, initial reference area A, reference area B, tolerance Δ.

Claims (1)

[Claims] 1 Initial reference data (A) of the captured images of the inspection objects (W, W1, W2...Wn) that are sequentially sent to the set inspection station (S) are set in advance, and this initial reference data (A) is set in advance. ) and the inspection object (W, W1, W2
...Wn) with the measurement data (A1, A2...An) of the inspection object (W, W1, W2...W
n) and at the same time determine the initial reference data (A) based on the measurement data (A1, A2...An) of the inspection objects (W, W1, W2...Wn) that have been determined to be good. The quality of the inspected object is determined based on a comparison between the corrected standard data (B) and the measured data of the inspected object, and at least the standard data is determined based on the measured data of the inspected object that has been determined to be non-defective. (B) A visual inspection method characterized by sequentially updating.