JP3033893B2 - Appearance inspection 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 visual inspection apparatus for capturing an image of a moving inspection object, performing predetermined signal processing, and performing a quality inspection or the like.

[0002]

2. Description of the Related Art Conventionally, as an appearance inspection apparatus for taking in an image of a moving inspection object and performing predetermined signal processing to perform a quality inspection or the like, for example, Japanese Patent Application Laid-Open No. 9-297107.
No., published in Japanese Unexamined Patent Publication No.

Further, by providing a plurality of illuminations for irradiating the projections of the inspection object from different angles and performing a plurality of image captures while sequentially switching these illuminations, a higher inspection performance can be obtained. Is the idea of Tokuho 9-3
No. 11020.

[0004]

However, when an image is captured by a line sensor, an image is captured only under one illumination condition for a continuous inspection object such as a sheet moving continuously. Could not.

In other words, in order to capture an image under different illumination conditions with the line sensor, it is necessary to move the line sensor or the image capture target once to capture the image, then switch the illumination condition and move again to capture the image. In the case where the inspection target is a continuous sheet or a component that moves continuously, such as a part moving on a conveyor, conventionally, the line sensor is used under different lighting conditions. Could not capture multiple images.

In addition, even when the image sensor is configured to capture an image from the line sensor under a plurality of illumination conditions, it is necessary to move the line sensor a number of times corresponding to the number of illumination conditions in which the image capture is desired. In particular, in a system for transporting from an inspection object whose image has been captured under a plurality of lighting conditions, the line sensor must be moved a plurality of times, and only from the inspection object whose image has been captured by the last movement. Since it could not be transported, it took a long time to start transporting.

[0007] Even if the image can be captured by moving over the image capturing target a plurality of times, if the same resolution as that of the image captured by the conventional method is to be obtained, the line at the time of image capture is required. Compared with the sensor, the illumination condition is, for example, half speed for two types, and 3 for three types of illumination conditions.
It is necessary to move the line sensor at one-half speed.

FIG. 3A shows an appearance inspection process.
As shown in (1), there is a process in which inspection target components are arranged, an image is captured under two types of illumination conditions, and the inspection target component after the image capturing is completed is transported to the next process.

In another processing step, as shown in FIG. 3B, an image is captured under one illumination condition for all parts arranged in one line, and then the illumination is switched to the second illumination condition. In the case of performing the image capturing in step (2), the image capturing of the first component is last in the second illumination condition, and the movement of the first component is delayed.

In addition, as shown in FIG. 3C, when a plurality of images are captured by switching the illumination condition for each component, the moving direction of the line sensor is changed twice for each component. In order to change, many acceleration and deceleration must be performed twice for each part. When the image capturing under the second lighting condition is completed for the first component, the line sensor
Since the first part is on the opposite side from the second part, to start capturing the image of the second part next,
You have to move to the second part. For the above two reasons, the method shown in FIG. 3C shows that the time from the start of image capture to the end of image capture under two types of illumination conditions is delayed for each component. .

[0011]

SUMMARY OF THE INVENTION A visual inspection apparatus according to the present invention is provided with a plurality of illuminations for illuminating an inspection object, and illuminating so that the illumination illuminates the inspection object for a predetermined time in a predetermined order. Control signal generating means for supplying a control signal to the means at a predetermined timing; a line sensor which moves relative to the inspection object illuminated by the illumination and captures an image of the inspection object; An image signal captured by the sensor is stored at the timing of the control signal, and an image storage unit that sends out the image signal captured at the previous timing, an image signal sent from the image storage unit, and a preset image signal. A determination unit configured to determine the inspection target based on comparison with a reference.

The illumination range of the illumination is ring-shaped, line-shaped,
Or it may be dome-shaped.

[0013] The inspection object may be illuminated by sequentially switching the plurality of illuminations by a control signal generation means. The control signal generation means may illuminate the plurality of illuminations in any combination. Alternatively, a configuration may be adopted in which the combination of lighting is sequentially switched.

In other words, the visual inspection apparatus of the present invention switches the illumination to be turned on for each line scan of the line sensor during movement so that the line sensor captures an image. And a plurality of different images.

In the case where two lights are used in the visual inspection apparatus of the present invention, the control signal generating means generates a line clock of the line sensor, sends the line clock to the line sensor, and the first lighting lighting means and the first lighting lighting means. The second lighting means is provided with one of the line clocks in synchronization with the line clock.
An illumination lighting signal is generated so that the illumination is alternately turned on every other line. In the image storage unit, the image signals are alternately stored in different storage areas for each line by the line clock from the control signal generation unit, so that a plurality of images having different illumination conditions can be captured by one line sensor movement. .

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, the line sensor 1 captures an image of an object to be inspected, in this example, a part while moving in a direction orthogonal to the scanning direction of the line sensor 1 by the moving means 2.

On the other hand, the control signal generating means 3 supplies a line clock for capturing an image to the line sensor 1 and synchronizes the first lighting lighting means 4 and the second lighting lighting means 6 with the line clock, respectively. Then, an illumination lighting signal is sent so that the two illuminations are alternately turned on.

The first illumination lighting means 4 turns on the first illumination 5 when the lighting signal from the control signal generating means 3 is on, and turns off the light when it is off. Similarly, the second illumination lighting means 6 turns on and off the second illumination 7 according to the lighting signal from the control signal generation means 3.

The analog image signal output from the line sensor 1 is converted into a digital image signal by the AD converter 8 and output to the image storage 9. The image storage means 9 fetches a line clock from the control signal generation means 3 and, based on the line clock, determines a storage area for the input digital image signal from the AD conversion means and stores it.

Therefore, as shown in FIG. 1, when the illuminations are the first and second illuminations 5 and 7,
Each time a line clock is input, two image storage areas are alternately switched to store image data.

The image processing means 10 reads out the first image data from the image storage means 9 when the first illumination 5 is turned on, and reads out the second image data when the second illumination is turned on. A predetermined image processing is performed, and a first measurement value and a second measurement value, which are the respective image processing results, are calculated and output to the determination unit 11.

The judging means 11 makes a pass / fail judgment on the basis of the first measured value and the second measured value output from the image processing means 10 according to a predetermined judging standard.

Next, the operation of the appearance inspection apparatus of FIG. 1 will be described with reference to FIG.
This will be described with reference to FIG.

FIG. 2 shows a timing chart of the line clock and two illumination lighting signals. The control signal generator 3 outputs a line clock having the waveform shown in FIG. 2 to the line sensor 1 and the image storage 9. The line sensor 1 charges the CCD while the line clock is Low, and outputs the image signal charged in the previous line.

The image storage means 10 has a number of image storage areas corresponding to the number of illumination conditions, in this example, the number of illuminations, and each time the line clock switches from low to high,
The area for storing the image is sequentially switched.

The control signal generating means 3 generates a plurality of illumination lighting signals in synchronization with the line clock. FIG.
A case where a lighting signal is generated by alternately switching two lights is shown. In synchronization with a line clock, when the first lighting lighting signal is on, the second lighting lighting signal is turned off, and the first lighting is turned off. When the lighting signal is off, a signal is generated such that the second lighting lighting signal is turned on.

Therefore, when the first illumination lighting signal is on, the image storage means 9 sets the line sensor 1 to
By charging the image with the illumination of the first illumination 5 and outputting the image signal captured at the time of the previous illumination of the second illumination,
The digital image signal that has been A / D converted in real time is stored in the second storage area. Conversely, when the second illumination lighting signal is on, the image sensor 9 charges the image with the second illumination,
Then, the captured image signal is output when the illumination is turned on, and the digital image signal that has been A / D converted in real time is stored in the first storage area.

The processing step in which the advantages of the visual inspection device of the present invention are most effectively exhibited is as shown in FIG. This is a step of transporting the inspection target component from which the image has been captured to the next step. In this case, according to the present invention, when the line sensor has passed once over the image capturing target component, the image of the component has been captured under two types of lighting conditions. The finished parts can be conveyed to the next step by, for example, sucking them from above in order.

In the embodiment shown in FIG. 1, the line sensor and the illumination are moved to take in an image. However, the present invention can be applied to the case where the line sensor and the illumination are fixed and the object to be inspected moves. Image capture is possible.

The shape of the illumination is not limited to the ring shape as shown in FIG. 1, but may be a line shape or a dome shape. Further, the number of lights is not limited to two, but a method of sequentially switching three or more lights to take in an image, and a method of lighting a plurality of lights in any combination and sequentially changing the combination of lights. A method of switching and taking in an image can also be applied.

Further, in addition to the means for sequentially storing the image data in different storage areas for each line clock as the image storage means 10, the image storage means 10 stores the images of all the line clocks in the same storage area and then stores the image data when reading out the image data. A method of reading from an address calculated in advance as an image under the same illumination condition is also conceivable.

As the plurality of illumination lighting means, in addition to the method of directly turning on and off the illumination, a mechanical shutter or a liquid crystal shutter is provided between each illumination and the part to be inspected while the illumination is kept on. It is also conceivable to turn on / off the shutter by using a switch.

[0034]

As described above, according to the appearance inspection apparatus of the present invention, an image can be captured in a short time under a plurality of illumination conditions using a line sensor. In addition, by switching a plurality of illumination conditions in synchronization with the line clock of the line sensor to capture an image, it is possible to capture images under a plurality of illumination conditions in one movement. Therefore, it is possible to perform a high-accuracy appearance inspection at a high speed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a visual inspection device according to an embodiment of the present invention.

FIG. 2 is a timing chart of signals of each unit in the appearance inspection apparatus of FIG. 1;

FIGS. 3A, 3B, and 3C are explanatory diagrams showing image capturing modes of a conventional visual inspection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Line sensor 2 Moving means 3 Control signal generating means 4 First illumination lighting means 5 First illumination 6 Second illumination lighting means 7 Second illumination 8 AD conversion means 9 Image storage means 10 Image processing means 11 Judgment means

Claims (4)

(57) [Claims] 1. A control for supplying a control signal to illumination lighting means at a predetermined timing so that a plurality of illuminations for illuminating an inspection object and each illumination illuminates the inspection object for a predetermined time in a predetermined order. A signal generation unit, a line sensor that moves relative to the inspection object illuminated by the illumination and captures an image of the inspection object, and an image signal captured by the line sensor, the control signal Image storage means for storing the image signal sent at the previous timing and sending out the image signal captured at the previous timing; and the image signal sent from the image storage means, and comparing the image signal sent from the image storage means with a preset reference. And a determination unit for performing a determination of (1). 2. The visual inspection device according to claim 1, wherein the illumination range of the illumination is a ring shape, a line shape, or a dome shape. 3. The visual inspection device according to claim 1, wherein the control signal generating means is configured to sequentially switch the plurality of illuminations to illuminate the inspection object. 4. The visual inspection apparatus according to claim 1, wherein the plurality of lights are turned on in an arbitrary combination by the control signal generating means, and the combination of the lights is sequentially switched.