JPS63164690A - Visual equipment - Google Patents

Abstract

PURPOSE:To eliminate the influence of the variation in background light (disturbance light) by generating image signals made from background light only and image signals made from background light and illumination light for each frame, and generating image information while comparing these image signals with each other. CONSTITUTION:A vertical synchronizing signal 8 from an inter-image differential calculator 5 is inputted to an illumination controller 6, and the controller 6 controls an illuminator 4 to turn on/off its illuminating action based on the signal inputted to itself 6. A signal 9 representing the absolute value of a differential signal generated from the difference between an ITV camera image signal obtained during a time when the illuminator 4 is not lighted and an ITV camera image signal obtained while the illuminator 4 is lighted, is generated joinly by a delay circuit 13, a subtraction circuit 14, and an absolute value circuit 17. As a result, an image signal free from the influence of disturbance light is obtained, and the reliability of the image processing can remarkably improved.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a visual device, and in particular to a visual device for identifying and positioning objects, which is useful as a device that exhibits visual functions in intelligent robots, etc. It is.

(Prior Art) Industrial visual devices generally include a lighting device that irradiates light onto an object, an ITV camera that projects the object, and an image signal related to the object obtained by the ITV camera. It is composed of an image processing device that performs processing to identify objects and measure their positions. Such industrial visual devices typically play an important role as basic components that exhibit perceptual functions in visual inspection devices and intelligent robot systems that promote automation of production processes.

In conventional visual devices, the image obtained by the ITV camera is stored in the image memory of the image processing device for one screen, and the stored image information is processed as required and the necessary results are output. Ta.

On the other hand, as lighting means to irradiate light onto the object, natural light may be used as is, incandescent lamps, fluorescent lamps, LEDs,
Various lighting equipment such as lasers were used. Conventionally, when performing this illumination, there is no synchronization between the illumination operation of the illumination device and the image input operation of the IT camera, except for special applications such as strobes used to keep moving objects still. I was never let down.

(Problems to be Solved by the Invention) Incidentally, the image processing device of the above-mentioned visual device usually performs binarization processing on an analog image signal obtained from an ITV camera in order to recognize an object.

In the current most common binarization process, an appropriate threshold value is set for the brightness level, and the image density of image parts that are brighter than this threshold is "1", and the image density of image parts that are darker than this threshold is "0". ”, the object is extracted as a silhouette using the binarized image obtained in this way, and the area of the “1” part is calculated for this binarized image. It becomes possible to recognize objects and measure their positions. Therefore, in a visual device, it is required that the brightness of an object, that is, the brightness of an input image, does not change in relation to a threshold value set for image processing.

However, when the visual device is used, for example, as a visual inspection device, the visual device is generally placed near a production line in a factory. The brightness inside a factory is generally not constant; for example, the brightness differs between day and night, and between summer and winter. Furthermore, there are welding equipment and various light sources in the factory, and these also affect the brightness inside the factory. In this way, it is difficult to maintain a constant brightness in the factory where the visual equipment is installed, and the brightness of the image input to the ITV camera changes due to ambient light. A problem arises in that image processing cannot be performed stably. That is, as a result of the image signal output from the ITV camera changing depending on the brightness of the object, the binarized image changes,
This increases the possibility of erroneous recognition and a decrease in measurement accuracy.

An object of the present invention is to provide a visual device that eliminates the influence of the change in brightness on an output signal when the brightness of an input image changes due to ambient light in image processing of the visual device. It is in.

(Means for Solving the Problems) The visual device of the present invention includes an illumination device that irradiates light onto an object, an imaging device that takes m images of the object, and an image signal that processes the image signal output from the imaging device. In a visual device that includes an image processing device that outputs information about an object, a vertical synchronization signal is separated from an image signal, and the image signal from which the vertical synchronization signal has been separated is separated from the image signal one screen before, which is obtained in the same way. an image difference calculation device that obtains a difference signal from an image signal, converts this difference signal into an absolute value, and outputs it to an image processing device; and an image difference calculation device that receives a separated vertical synchronization signal and, in response to this, controls the lighting device. and a lighting control device for controlling the lighting device to alternately change the level between two levels.

(Function) According to the visual device of the present invention, an image signal based on only background light and an image signal based on background light and illumination light are obtained alternately every frame, and these image signals are compared to obtain image information. Therefore, it is possible to eliminate the influence of fluctuations in background light (disturbing light) in the output image information.

(Example) The present invention will be described in detail below based on the accompanying drawings.

FIG. 1 shows the overall configuration of a visual device according to the present invention. In this figure, 1 is a workpiece to be imaged and image-processed for the purpose of inspection or processing, etc., and 2 is an image signal 3 obtained by imaging the workpiece 1. Industrial television camera (hereinafter referred to as rIT) that outputs
(referred to as "V camera"), 4 is a lighting device that irradiates light onto the workpiece 1, and provides the required level of brightness to the workpiece 1 at an appropriate timing as necessary. 5 is the difference between images. The inter-image difference calculation device 5 separates the vertical synchronization signal 8 from the image signal 3 output from the ITV camera 2, and converts the vertical synchronization signal into 8 to the illumination control device 6 , the image signal from which the vertical synchronizing signal 8 is separated is processed, and the resulting output image signal 9 is sent to the image processing device 7 .

The lighting control device 6 inputs the vertical synchronization signal 8 from the image difference calculation device 5, and turns on/off the lighting operation of the lighting device 4 based on this signal. That is, the lighting device 4 is caused to blink at high speed by a control signal (hereinafter also referred to as a drive signal) 10 from the lighting control device 26. Therefore, in the lighting device 4,
Typically, an LED, laser, etc. is used that is responsive to the control signal 10 and whose brightness can be changed rapidly. Furthermore, any light emitting source can be used as long as it has similar characteristics. Next, the specific configurations of the image difference calculation device 5 and the illumination control device 6 will be explained based on FIGS. 2 and 3, respectively.

FIG. 2 shows a specific configuration of the image difference calculation device 5. In this figure, 11 is a synchronization signal separation circuit, and this circuit separates the vertical synchronization signal 8 from the ITV camera image signal 3 from the ITV camera 2. At the same time, the synchronization separated image signal 12 from which the vertical synchronization signal has been separated is supplied to the delay port #113 and the subtraction circuit 14. The delay circuit 13 delays the input synchronously separated image signal 12 by a time corresponding to one frame, and outputs it as a previous frame image signal 15. The delay time in the delay circuit 13 is determined according to the video signal standard, and for example, in the NTSC video signal standard, it is set to 1/30 seconds for interlaced scanning and 1/60 seconds for non-interlaced scanning. Additionally, as the delay circuit 13, a frame memory can be used in addition to a general delay circuit. 14 is the above-mentioned subtraction circuit, and this circuit extracts the image signal 1 one screen before from the synchronous separated image signal 12.
5 is subtracted and a difference signal 16 is output. 17 is an absolute value circuit which converts the difference signal 16 into an absolute value and outputs it as an output image signal 9.

FIG. 3 shows a specific configuration of the lighting control device 6. As shown in FIG.

The lighting control device 6 includes a flip-flop 18 and a drive port B19.
In this embodiment, the lighting device 4 is made to blink;
An example is shown in which the ITV camera 2 is operated in a non-interlaced scanning manner. The flip-flop 18 inverts the state of its output 20 from "1" to "rO" or from "0" to "1" every time a pulse of the vertical synchronizing signal 8 is input. The drive port 1!319 outputs a drive signal 10 that controls the blinking operation of the lighting device 4. Specifically, when the signal input from the flip-flop 18 is "0", the output voltage becomes O, and when the signal input from the flip-flop 18 is "1", the drive circuit 19 outputs a voltage sufficient to turn on the lighting device 4. .

Next, the operation of the visual device having the above configuration will be explained with reference to FIG. 4□. FIG. 4 shows each of the aforementioned signals 3°8.9.
10 is a timing chart showing states of No. 10.

First, the ITV camera 2 generally uses a storage type image sensor. This image sensor converts the accumulated amount of incident light into voltage and outputs it only during one frame period, and there are two types of accumulation methods: a frame transverse type and an incline type. In one type of frame transfer, the amount of accumulated light 'Vi' within a period separated by the pulses of the vertical synchronizing signal is output, and this method is adopted in this embodiment. Therefore,
In FIG. 4, the period 21.22.23 determined by the pulse of the vertical synchronization signal 8 indicates the period of one frame, and as shown in the ITV camera image signal 3, the period 21.22.23
The amount of light accumulated in each period is output as a voltage in the next frame period. Although the ITV camera 2 in this embodiment is suitable for use with a frame transfer type image pickup element as described above, it is also possible to use an almost equivalent image pickup tube such as a Sachicon.

Next, a method for creating the output image signal 9 to be supplied to the image processing device 7 will be explained. The control signal for blinking the lighting device 4, that is, the lighting device drive signal 10, alternates between the states “0” and “1” in accordance with each pulse of the vertical synchronization signal 8. In the example shown in FIG. 4, it becomes "0" in response to the first pulse of the vertical synchronization signal 8, becomes "1" in response to the second pulse, and thereafter becomes "1" in response to each subsequent pulse. By repeating this process, in the ITV camera image signal 3, an image signal for one frame is output while the state of the vertical synchronization signal 8 is "0". Then, in the period 21, the lighting device drive signal 10 is "0", so the lighting bag r
! 14 is not lit, therefore, the ITV camera image signal 3 output in the period 22 becomes an image signal obtained only by background light without illumination by the illumination device 4. On the other hand, in the period 22, the driving signal 10 is "1", so the illumination device 4 is turned on, and therefore the ITV camera image signal 3 output in the period 23 is a combination of the light given by the illumination device 4 and the background light. It is an image signal obtained by light. As a result, the output image signal 9 obtained in the period 23, for example, is divided into the ITV camera image signal obtained in the period 23 and the ITV camera image signal obtained in the period 22 by the effects of the delay circuit 13, the subtraction circuit 14, and the absolute value circuit 17 described above. The signal is the absolute value of the difference signal obtained by taking the difference from the image signal. Similarly, regarding the output image signal 9 obtained in other periods 21 and 22, the two I
Created by TV camera image signals.

According to the method for creating the output image signal 9 as described above, the change in background light is generally caused by the pulse period of the drive signal 10 (in this case, 1
/60 seconds), so by calculating the difference signal 16 between two ITV camera image signals in adjacent periods using the above configuration, the output image input to the image processing device 7 is In the signal 9 the influence of background light can be canceled. In other words, the image signal 9 to be processed in the image processing device 7 has background light,
In other words, a high-quality image signal is obtained that is not affected by ambient light, and the reliability of image processing can be greatly improved.

In the above embodiment, the illumination device 4 was controlled to blink, but the influence of ambient light on the output image signal can be similarly eliminated by simply controlling it to switch between two different brightness levels. . Further, in the case of the interlaced scanning method, a similar effect can be obtained by changing the brightness of the illumination device 4 every two vertical synchronizing signal pulses.

Next, using the timing chart of FIG.
The implementation sequence will be explained. This embodiment also has the same basic configuration as the previous embodiment.

The difference is that an incline storage type image sensor is used as the ITV camera 2. In the incline method, the voltage of each pixel to be output is determined by the amount of light accumulated in a period one frame time before immediately before output. Further, in this embodiment, the configuration of the lighting control device 6 that controls the blinking operation of the lighting bag W4 is also different so that the following effects occur.

The operation of this embodiment will be explained based on FIG.

When the vertical synchronization signal 8 is "1", it is generally called a vertical blanking period, during which the ITV camera 2 stops outputting an image signal. Therefore, during the first vertical blanking period of the period 21, the illumination device drive signal 10 becomes "1" in synchronization with the vertical synchronization signal 8, and the illumination device 4 is turned on to illuminate the object. Therefore, the image signal output in the period 21 is a signal that is a combination of illumination light and background light.In the first period 22, the driving signal 10 does not become "1" during the immediately preceding blanking period, so the illumination device 4
is not lit, and the image signal output during this period 22 is a signal of only background light.

As described above, in each period, an image signal generated from illumination light and background light and an image signal generated only from background light are generated alternately. Therefore, similarly to the above embodiment, the image difference calculation device 5
By calculating the absolute value of the difference between the image signals of period 21 and period 22 using the delay circuit 13, subtraction circuit 14, and absolute value circuit 17, the illumination bag'r! It is possible to extract an image signal based on 14 lights, and it is possible to eliminate the influence of changes in ambient light.

This embodiment is most suitable when using a small ITV camera that uses a solid-state image sensor.

Further, in this embodiment as well, an LED, a laser, etc. are used for the illumination device 4 as in the previous embodiment, and it can be applied to interlaced scanning and non-interlaced scanning.

(Effects of the Invention) As is clear from the above explanation, according to the present invention, it is possible to obtain a stable and highly reliable input image signal that is not affected by ambient light, so that stable image processing can be performed in the visual device. I can do kotoa.

Further, by applying the visual device according to the present invention, the reliability of automatic inspection devices, robot systems, etc. can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic configuration of a visual device according to the present invention, FIG. 2 is a block diagram showing an example of a specific configuration of an image difference calculation device, and FIG. 3 is a specific configuration of a lighting control device. FIG. 4 is a timing chart for explaining the operation of the first embodiment, and FIG. 5 is a timing chart for explaining the operation of the second embodiment. [Explanation of symbols...Work 2...ITV camera 3...Image signal 4...Lighting device 5...Inter-image difference calculation device 6...Lighting 1lJtn device 7...Image processing device 8...Vertical synchronization signal 10...Control signal (drive signal) 11...
・Synchronization signal separation circuit 13... Delay circuit 14... Subtraction circuit 17... Absolute value circuit

Claims (3)

[Claims] (1) Includes an illumination device that irradiates light onto an object, an imaging device that takes an image of the object, and an image processing device that processes an image signal output from the imaging device and outputs information regarding the object. A visual device comprising: separating and outputting a vertical synchronization signal from an image signal output by the imaging device;
A difference signal between an image signal from which the vertical synchronization signal has been separated and an image signal of one screen before obtained in the same manner is obtained, and this difference signal is converted into an absolute value and outputted to the image processing device. and a lighting control device that receives the vertical synchronization signal and controls the lighting device so that the lighting device alternately changes its lighting level between two levels in response to the vertical synchronization signal. Characteristic visual device. (2) The lighting control device controls the lighting device to synchronize with the vertical synchronization signal and emit light at two different levels of brightness for each vertical synchronization signal. Visual apparatus. (3) The lighting control device controls the lighting device so as to synchronize with the vertical synchronization signal and emit light only during the vertical blanking period once for every two consecutive pulse signals of the vertical synchronization signal. The visual device according to item 1.