JP3035578B2 - Inspection condition determination device, inspection device, and shutter speed determination device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for inspecting a sequentially moving object row for each object, and more particularly to an inspection condition determining apparatus for changing the inspection conditions to conditions suitable for the object. , An inspection condition determination method and an inspection apparatus. For example, the present invention relates to changing inspection conditions such as a shutter speed of an inspection device that inspects an object by detecting each object flowing on a belt conveyor and imaging the object.

[0002]

2. Description of the Related Art Conventionally, of a sequence of sequentially moving objects, each of the images obtained by detecting that each object has entered an imaging area, imaging the object, and imaging the object. There is an inspection device that inspects each object based on data.

In this inspection apparatus, inspection conditions can be changed in order to set an object under appropriate inspection conditions. Therefore, under various inspection conditions, an object is imaged, and image data most suitable for inspection is extracted from image data obtained by imaging, and set as inspection conditions when the image data is imaged. We have that.

FIG. 3 shows an external appearance when an object is inspected by the inspection apparatus. The inspection device 1 includes a camera 2, a lighting device 3, an image processing unit 4, and a photoelectric switch 5. During the inspection, the rows of objects 6 are
Move sequentially in the direction of the arrow. Photoelectric switch 5
Outputs to the image processing unit 6 that the object 6 has entered the imaging area 8 of the camera 2. Here, the imaging region 8 is set to have a size that allows only one target object 6 to enter. Alternatively, the rows of the target objects 6 are formed with an interval between the target objects so that only one target object 6 enters the imaging region 8. The image processing unit 4 causes the camera 2 to image the object 6 in response to receiving an entry detection signal indicating that the object has entered the imaging area from the photoelectric switch 5. The camera 2 outputs an image signal obtained by capturing an image to the image processing unit 4.

[0005] The image processing unit 4 converts the received image signal into image data, performs image processing to calculate a feature amount, and obtains a reference feature amount registered in advance and actual imaging. Inspection of the quality of the target object 6 is performed by obtaining a correlation value with the obtained feature amount and comparing the values.

Here, the illumination device 3 may illuminate each time an image is taken, or may always illuminate. Here, the camera 2 and the lighting device 3 are integrally configured.
The image processing unit 4 performs image processing on the image data, and outputs an inspection result of the object to the outside.

When inspecting the object 6 using the camera 2, it is necessary to obtain an appropriate image signal. In this case, inspection conditions such as the shutter speed, illumination brightness, and imaging area of the camera 2 must be set to appropriate values.

Conventionally, in order to set these inspection conditions, the belt conveyor 7 is stopped, the stationary object 6 is arranged in the imaging area 8 of the camera 2, and the inspection conditions are changed every time an image is taken by the camera. Camera 2 to image the object
The image signal of the object corresponding to each inspection condition is acquired, and the image signal which is most suitable for the inspection is determined among the image signals acquired by performing image processing on the image signal, and the most suitable image signal is determined. The value of the inspection condition at the time of acquisition was determined. Then, the inspection conditions of the inspection apparatus 1 are set with the obtained values, and the object 6 is actually inspected sequentially.

[0009]

However, in the prior art, in order to determine the inspection condition corresponding to the object 6, the object 6 is imaged by the camera 2, and the inspection condition corresponding to the captured image is determined. Was. In order to image the object 6 with the camera 2, the object 6 on the stopped belt conveyor 7
Was imaged. However, during the inspection, the belt conveyor 7 is operating, and an image captured when the inspection conditions are determined (when the belt conveyor 7 is stopped) and an image captured during the inspection (when the belt conveyor 7 is operating). And was different. For this reason, there has been a problem that the inspection conditions obtained at the time of setting the inspection conditions are not always appropriate at the time of actual inspection.

For example, when the entry of the object 6 is detected by the photoelectric switch 5 and the image of the object 6 is taken by the camera 2, the position of the object 6 in the imaging area 8 is determined when the inspection conditions are set and when the actual inspection is performed. And may be different. Because the belt conveyor 7 is always moving at the time of inspection, the target object 6 cannot be accurately arranged at a position where the photoelectric switch 5 detects the object 6 on the belt conveyor 7 at the time of setting the inspection conditions. is there.

Further, when an image of the object 6 on the moving belt conveyor 7 is taken at the time of inspection, the inspection may be performed based on blurred image data because the object is moving. On the other hand, when an image of a stationary object is taken at the time of setting the inspection condition, the inspection condition is set based on an image in which the object 6 is not blurred. As described above, there is a case where an image obtained by capturing the moving object 6 at the time of the inspection is different from an image obtained by capturing the stationary object 6 at the time of setting the inspection condition.

Furthermore, when setting the inspection conditions, usually only non-defective objects are used for setting the inspection conditions. However, although the objects are non-defective, there is a slight individual difference in shape, pattern, and the like. Therefore, it is necessary to set the inspection conditions by appropriately replacing non-defective objects, and there is a problem that the inspection is complicated.

[0013] The present invention has been made in view of these problems, and is to make it possible to set the inspection conditions by setting the inspection environment the same at the time of setting the inspection conditions and at the time of the actual inspection. Further, it is a technical task to set an inspection condition in consideration of an individual difference of an object.

[0014]

According to the first and second aspects of the present invention, in a sequence of sequentially moving objects, it is sequentially detected that each of the objects has entered the imaging area, and each time the object is detected, the object is detected. It is characterized in that imaging conditions are changed each time imaging is performed, and inspection conditions suitable for inspection are set based on an image signal obtained by imaging.

According to a third aspect of the present invention, in the sequence of sequentially moving objects, it is sequentially detected that each object has entered the imaging area, and the object is imaged by the camera each time the object is detected. The present invention is characterized in that the shutter speed of the camera is changed and a shutter speed suitable for inspection is set based on an image signal obtained by imaging.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The processing at the time of inspection of an inspection apparatus according to an embodiment of the present invention is the same as that described in the section of the prior art, so that the description of the inspection of the inspection apparatus will be omitted. An inspection condition setting different from that of the related art will be described.

When the inspection conditions are set, the belt conveyor 7 is operating, and the object 6 on the belt conveyor 7 is moving at a constant speed in the direction of the arrow. A photoelectric switch 5 for detecting that the object 6 has entered the imaging area 8 of the camera 1 is installed beside the belt conveyor 7. When the photoelectric switch 5 detects the entry of the object 6 into the imaging area 8, the photoelectric switch 5 outputs an entry detection signal to the image processing unit 4. The image processing unit 4 causes the camera 2 to image the object in response to receiving the entry detection signal, obtains an image signal, and repeats this process a predetermined number of times, changing the inspection condition each time the image is captured. And
By performing image processing on the obtained image signal, an image signal most suitable for inspection is determined, and an inspection condition corresponding thereto is determined.

A configuration example of the inspection apparatus 1 will be described. FIG. 1 shows a configuration example of the inspection apparatus 1. The camera 2 includes a lens 10, an aperture system 11, a light receiving unit 12, an image signal conversion unit 13, a shutter speed adjustment unit 14 , and a shutter speed control unit 15.

An image to be picked up is received by a light receiving section 12 through a lens 10 and an aperture system 11, and a video signal is output to an image signal converting section 13. The output video signal is
It is converted into an image signal and output to the image processing unit 4. Upon receiving the image signal, the image processing unit 4 converts the image signal into image data. Inspection conditions are determined based on the image data.

The light receiving section 12 uses a CCD image pickup device, and uses an electronic shutter type image pickup means. The shutter speed control unit 14 changes the brightness of the image by controlling the charge accumulation time of the CCD image sensor of the light receiving unit 12.

The photoelectric switch 5 outputs an entry detection signal to the image processing unit 4 when detecting entry of an object into the image pickup area.
Output to The illumination device 3 illuminates the target 6 in the imaging region of the camera 2 or constantly illuminates the imaging region according to the imaging timing.

Next, the processing for setting the inspection conditions of the image processing section 4 will be described with reference to a flowchart. FIG. 2 shows a flowchart of the inspection condition setting process. Note that “ST” in the figure corresponds to “step” in the text.

First, it is determined whether an entry detection signal from the photoelectric switch 6 has been input to the image processing unit 4 (step 1). No further processing is performed until there is an entry detection signal. When the entry detection signal is input, the image processing unit 4 causes the camera 2 to image the target (Step 2). Then, the image signal output from the camera 2 is converted into image data by taking an image, and the fitness of the inspection is calculated for the image data (step 3). The calculation of the degree of conformity of the inspection will be described later. At this time, the image processing unit 4 stores the value of the inspection condition at the time of imaging in association with the calculated conformity. In the embodiment of the present invention, the shutter speed is used as one of the inspection conditions, and the value of the shutter speed is stored here.

Next, the inspection conditions are changed (step 4). In the present embodiment, the shutter speed is changed as one of the inspection conditions. Other inspection conditions for the shutter speed include the brightness of the illumination and the aperture. When changing the brightness of the illumination, a brightness control unit for controlling the brightness of the illumination of the illumination device 3 may be added to the configuration of the inspection device 1. When changing the aperture, an aperture control unit for controlling the aperture amount of the aperture system 11 may be added to the configuration of the inspection apparatus 1. The inspection condition setting process is performed by designating a specific inspection condition as needed.

Under the changed inspection conditions, the camera 2
The image processing unit 4 determines whether or not the object 6 has been imaged a predetermined number of times , and the camera 2 performs imaging under different inspection conditions until the predetermined number of times is reached (step 5). If the image has been captured up to a predetermined number of times,
The suitability of the best value is obtained, and the inspection condition corresponding to the inspection condition and the suitability stored in the image processing unit 4 is determined. In the case of the suitability of the shutter speed, the closest suitability to the predetermined suitability is obtained as the best suitability. Alternatively, two or three degrees of fitness may be determined from the plurality of degrees of fitness calculated, and the average of the values of the inspection conditions corresponding to each degree of fitness may be calculated to determine the inspection conditions.

The inspection apparatus 2 is operated under the determined inspection conditions.
Is set, and the actual inspection of the object 2 is performed.

Finally, the calculation of the degree of conformity of the image inspection with respect to the shutter speed will be described. First, a description will be given of a case where the degree of conformity is calculated for an object whose surface is plain. By changing the shutter speed, the brightness of the obtained image changes. Therefore, in order to perform inspection under the optimum inspection conditions, it is necessary to set the shutter speed so that the brightness of the obtained image becomes an appropriate value.
Consider a case where the obtained image data is grayscale image data.
When the number of pixels in the vertical direction is M and the number of pixels in the horizontal direction is N, and gray-scale image data of a total of M × N pixels is obtained, the gray-scale value of each pixel is represented by
(I, j). Where i = 0, 1, 2,..., M
−1, j = 0, 1, 2,..., N−1. The average brightness D of the image in this case is obtained by the following equation (Equation 1).

[0028]

(Equation 1) The value of the shutter speed at the time of capturing an image when the average brightness calculated by this equation is closest to the predetermined reference average brightness may be set as the inspection condition.

Next, a description will be given of a case where the degree of conformity is calculated for an object having a pattern such as a character on the surface of the object. An image suitable for inspection is an image having a clear contrast. That is, the image having the largest variance of the image is suitable for the inspection. When the number of pixels in the vertical direction is M and the number of pixels in the horizontal direction is N, and when gray-scale image data having a total number of M × N pixels is acquired, the gray-scale value of each pixel is defined as I (i, j). Where i = 0, 1, 2,..., M−1, j = 0, 1,
2, ..., N-1. The variance of the image in this case is
It is obtained by the following equation (Equation 2).

[0030]

(Equation 2) What is necessary is just to set the value of the shutter speed at the time of capturing the image when the variance value calculated by this formula is the largest as the inspection condition.

[0031]

According to the first and second aspects of the present invention, each time an object enters the imaging area, the image of the object is captured, and image data is acquired by changing inspection conditions such as a shutter speed. Since the inspection conditions suitable for the inspection are set based on the respective image data, the inspection conditions can be set in the same environment as in the actual inspection. Can be set.

According to the third aspect of the present invention, by changing the shutter speed as an inspection condition and imaging an image, the inspection condition can be set with lightness suitable for the inspection.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an inspection device.

FIG. 2 is a flowchart illustrating a process of setting an inspection condition of the inspection apparatus.

FIG. 3 is an external view showing an external appearance of the inspection device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 inspection device 2 camera 3 lighting device 4 image processing unit 5 photoelectric switch 6 object 7 belt conveyor 8 imaging area 10 lens 11 aperture system 12 light receiving unit 13 image signal conversion unit 14 shutter speed control unit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G06T 1/00 G01N 21/89 G06T 7/00 H04N 7/18

Claims (3)

(57) [Claims] And object detecting means for detecting that enters the imaging area of 1. A object IMAGING means captures an object in response to said object detecting means detects an object and imaging Imaging means for outputting an image signal obtained by the above, an inspection condition setting means for setting an inspection condition when inspecting an object, and setting by the inspection condition setting means based on an image signal from the imaging means. In the inspection condition determination device for determining the inspection condition, a temporary inspection condition of the inspection is set as a temporary inspection condition by the inspection condition setting means, and each of the sequentially moving target objects enters the imaging region. That the detecting means sequentially detects the object, an image of the object is captured by the image capturing means at each detection, and the temporary inspection condition is changed and set by the inspection condition setting means at each image capturing, and the image is captured. To Determining a temporary inspection condition when an image signal suitable for the inspection is acquired based on the respective image data acquired by the above, and setting the inspection condition based on the temporary inspection condition. apparatus. And object detecting means for detecting that enters the imaging area of wherein objects IMAGING means captures an object in response to said object detecting means detects an object and imaging An imaging unit that outputs an image signal obtained by the imaging unit, an inspection condition setting unit that sets predetermined inspection conditions, and an object inspection unit that inspects an object by performing image processing on an image signal from the imaging unit. In the inspection apparatus, a temporary inspection condition of the inspection is set as a temporary inspection condition by the inspection condition setting means, and the detection means detects that each of the sequentially moving object rows has entered the imaging area. Are sequentially detected at each detection, the object is imaged by the imaging means at each detection, and the tentative inspection conditions are changed and set by the inspection condition setting means at each imaging, and each is obtained by imaging. Based on the image data, it determines a temporary test conditions when acquiring the image signal suitable for the inspection, inspection apparatus and sets the inspection conditions based on the temporary examination conditions. And object detecting means for detecting that enters the imaging area of wherein the object is an imaging means captures an object in response to said object detecting means detects an object and imaging A camera that outputs an image signal obtained by the above, a shutter speed setting unit that sets a shutter speed when capturing an image of an object, and a shutter that is set by the shutter speed setting unit based on an image signal from the imaging unit. In the shutter speed determination device for determining a speed, a temporary shutter speed of the camera is set as a temporary shutter speed by the shutter speed setting means, and each of the sequentially moving target arrays enters the imaging area. The detection means sequentially detects the object, and the camera picks up an image of the object every time the detection is performed. Tsu is set to change the data rate,
A shutter characterized by determining a temporary shutter speed at the time of acquiring an image signal suitable for inspection based on each image data acquired by imaging, and setting the shutter speed based on the temporary shutter speed. Speed determination device.