JPS60207980A - Image capture apparatus and method - Google Patents

Abstract

PURPOSE:To enable reading of defects, marks etc., conducted on a surface of a properly at a high speed by lighting up plural light sources sequentially in different directions so as to illuminate objects and by obtaining necessary picture information after synthesizing pictures at every lighting-up. CONSTITUTION:GaAs solid-state laser light sources 1 and 2 which irradiate light at different angles with respect to an object 3 are alternately lighted up at a high speed by means of a laser driver 10. Pictures of the object 3 at every lighting-up are photographed by a television camera 5 through a filter 4 for transmitting light with the wavelength of the GaAs, and the obtained picture data are inputted to an AGC circuit 6, which controls gains so that the data can be widely distributed in accordance with maximum and minimum outputs and outputs them to a light amount correcting circuit 7. It corrects pictures so that picture data having the uniform amount of light can be obtained by giving gains reverse to those of an illumination light intensity distribution, and after it emphasizes edges of pictures with aid of an edge emphasis circuit 8, it outputs them to a picture processing device 9, which stores picture data at every picture by lighting-up so as to process them.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention can be used for defect inspection and automatic reading of objects such as marks that are difficult to recognize due to minute irregularities and cannot normally be obtained with sufficient contrast to obtain a desired image. The present invention relates to an apparatus and method for image capture.

Recently, images of objects are captured using COD or vidicon cameras for defect inspection in the materials industry, dimension measurement of parts and members, and automatic reading of stamped characters on the surface of parts. The need to perform image processing has increased. In conventional image capture devices,
When capturing images, a white light source such as a halogen lamp was used to illuminate the object. At this time, if a single light source is used for illumination, the influence of disturbance light (ambient light) on the captured image will increase, and the amount of light on the object will increase or decrease significantly due to changes in the light source distance. This method has the disadvantage that it is difficult to set binarization conditions for images containing images.

Furthermore, in order to eliminate the above-mentioned drawbacks, there are cases in which multiple light sources are turned on at the same time to uniformly illuminate the object, but even in this case, the illumination basically uses scattered light, so For example, in the case of engravings made on the surface of parts, it is not possible to uniformly illuminate the digit 0 for good judgment, so processing must be done using software using an image processing device, which is a time-consuming process. There were such drawbacks. Furthermore, when a plurality of the light sources mentioned above are turned on at the same time, there is a drawback that it is difficult to take advantage of the advantages of structuring.

An object of the present invention is to solve the above-mentioned problems and to obtain necessary image information by sequentially turning on multiple light sources installed at predetermined positions aa and capturing and synthesizing images for each light source.
It is an object of the present invention to provide an apparatus and method for image capture that can be quickly retrieved.

The present invention includes a plurality of light sources capable of turning on at high speed and arranged in a predetermined positional relationship so as to illuminate an object to be measured from different angles with light including a specific wavelength range, and controlling the lighting of the plurality of light sources by sequential switching. a light source driver, a filter that transmits only light in the specific wavelength range, an imaging device for capturing the light transmitted through the filter as an fI image for each light source, and adjusting the gain of the image captured by the III image device. a preprocessing circuit including an automatic gain control circuit for controlling the image, a light amount correction circuit for correcting image data so that the light m is uniform on the object, and an edge emphasis circuit for emphasizing the edge portions of the image; The device is characterized in that it includes a circuit 11111fl and an image processing device that processes images for each light source and performs desired measurements.

Furthermore, the present invention sequentially switches on and lights up a plurality of light sources arranged in a positional relationship that illuminates the measurement target from different angles, and captures a separate image for each light source turned on, thereby obtaining the desired result. It is characterized by capturing images.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram illustrating an embodiment of an image capture device of the present invention. In the example shown in FIG. 1, there are two light sources. The light sources 1 and 2 are composed of GaAs' solid-state lasers (output 20 mW, wavelength 830 nm), and are alternately turned on at high speed by a laser driver 10, which is a light source driver, under the control of an image processing device 9. The image of the object 3 for each lighting is the wavelength (8
T through a filter 4 that transmits only light of
The light enters the V camera 5 and is imaged at 1 lil. Imaged IC
Image data is first supplied to the AGC circuit 6. AGC
The circuit J3 in the circuit 6 controls the gain of the signal so that the data is widely distributed between the maximum output and the minimum output of each image, taking into account the dispersion of the image data. The image data that has been processed by the AGC circuit 6 is supplied to the light amount correction circuit 7, which obtains image data that changes the amount of illumination light on the object due to a change in the light source position and makes the amount of light uniform on the object. Correction is made by giving a gain opposite to the illumination light intensity (II) as shown in FIG.

The edge portions of the corrected image data are emphasized by the edge emphasis circuit 8, and then stored as digital values for each lighting image in the grain t in the image processing device 9.
It is used to perform image processing such as binarization. ” Dual AGC 6, light-to-light correction 7. The preprocessing circuit made up of each circuit of the edge enhancement 8 may be configured as an analog circuit, a digital circuit, or a circuit.

Next, we received an example of using an image capture device with a dual configuration, for example, for defect inspection during the tire manufacturing process.

First, let's consider a case where there is a V-shaped defect on a rubber sheet before vulcanization that is being moved on a belt conveyor as shown in Figure 2.
The image when illuminated by light source 1 is as shown in Figure 3, and since the 0 side of the V-shaped defect is displayed as a black level, it can be easily binarized and determined as a defect, but the V-shaped defect The black level of the 0th side of the image is not 1, but it is slightly different from the background, but it is a halftone, so it cannot be easily binarized and it takes a lot of effort to judge it as a defect. On the other hand, light source 2
As shown in FIG. 4, if the surface is illuminated by , it is easy to determine that surface 0 is defective, but it takes time and effort to determine surface 0. Therefore, it is not possible to accurately determine defects by binarizing an image using a single light source (only one of the images shown in Figure 3-4), and even if both light sources are illuminated at the same time, both C and D will become halftones. It was difficult to determine that it was a defect. Therefore, in the above-described configuration of the present invention, the images for each irradiation of the light source 1.2 are stored hierarchically in the gray memory in the image processing device 9, and the screens are overlapped in such a manner that they are ANDed. Defects are detected accurately.

In the image capturing apparatus and method of the present invention described above, in the conventional 211g processing of a single image, it takes a considerable amount of time to extract the necessary information using methods such as gray scale calculation on the image memory. However, by sequentially switching and using multiple structured light sources for some of these software processing, it is possible to extract the necessary information almost in real time, which is considerably faster than conventional methods. It has the advantage of being able to achieve high speed.

FIG. 5 shows the image capturing 7'J method according to the present invention/11! FIG. 3 is a diagram showing another example of a device for The first and second TV cameras 1 are placed at symmetrical positions on the vertical line on the measurement target 3.
1.12, and the first and second light sources 13.14 are also arranged symmetrically. Camera 11 and 1
Filters 15 and 1G that transmit light of specific wavelengths are arranged in front of the filters 2 and 2, respectively. These two TV cameras 13 and 14 are driven and controlled by a camera controller 17. The other configurations are the same as those of the embodiment described above, and the light sources 11J3 and 12 are driven and controlled by the image processing device 17 via the interface 18 and the light source driver 19, and the image signals from the TV cameras 13 and 14 are sent to the interface 20, the AGC Circuit 21. The image processing unit @
11. In this example, first, the first light source 11 is turned on, images are taken by the first and second TV cameras 13 and 14, and then the first light source 11 is turned off.
The second light source 12 is stippled and the first and second TV cameras 1:J3 and 14 perform @images. In this way, the image information of the four screens viewed from different angles can be input into the image processing device 17 separately, so that the necessary information can be accurately processed by appropriately processing them in the image processing device 17. Obtainable.

The present invention is not limited to the embodiments described above, and can be modified and changed in many ways. For example, in the above embodiment, two light sources were provided, but it is also possible to provide four light sources at an angle of 90° with the object to be measured as the center. Alphabella 1- can be accurately recognized. Further, in the above-described embodiment, the AGC5 light amount correction and edge enhancement processing were performed on the image as pre-processing, but other processing may be performed as pre-processing.

As is clear from the detailed explanation above, according to the image capturing method and method of the present invention, a plurality of light sources are sequentially turned on from different directions to illuminate an object, and each dot Since the necessary image information is obtained by combining the images of each image, it is possible to perform processes such as reading defects and markings on the surface of parts quickly and accurately. Furthermore, by combining a solid-state laser with a narrow band of wavelengths with a narrow band filter and a camera, the effects of ambient light and the like can be minimized. By passing the laser beam through a beam expander or the like, the directivity of the laser beam becomes even better, and the attenuation ratio due to distance becomes smaller than that of white light. Therefore, the distance relationship between the object and the light source can be freely controlled to some extent.

Furthermore, since the illumination can be made quite complex by using multiple light sources, there is an advantage that the degree of freedom in creating algorithms for extracting necessary image information is increased.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the image capture device of the present invention; FIG. 2 is a perspective view showing an embodiment of the present invention for inspecting defects in a rubber sheet portion; FIG. 3.4 The figure shows the state of images captured for each illumination, and FIG. 5 is a block diagram showing another embodiment of the image capture device of the present invention. 1, 2.11.12...Light source 3...Object 4,
15.16...Fi/Lz Yu5.13.14-TV camera 6.21...AGC circuit 7,22...Light amount correction circuit 8.23...Edge emphasis circuit 9.17... Image processing device 10.19...Light source driver. Figure 1 Figure 2 Figure 3 Figure 4 Cυ Figure 5

Claims (1)

[Claims] 1. A plurality of light sources that can be turned on at high speed and are arranged in a predetermined positional relationship so as to illuminate an object to be measured from different angles with light including a specific wavelength range, and these light sources are sequentially switched. a light source driver that controls lighting, a filter that transmits only light in the specific wavelength range, an imaging device that images and captures the light that has passed through the filter for each light source, and a gain of the image captured by this imaging device. a pre-processing circuit that includes an automatic gain control circuit that adjusts the amount of light on the object, a light amount correction circuit that corrects the image data so that the amount of light is uniform on the object, and an edge emphasis circuit that emphasizes the edge portions of the image; An image capture device according to claim 1, further comprising an image processing device that controls the device and the circuit, and processes images for each light source to perform desired measurements. 2. The image capture device according to claim 1, characterized in that a Qa AS solid state laser is used as the light source. 3. Capture the desired image by sequentially switching on and lighting multiple light sources arranged in a positional relationship that illuminates the measurement target from different angles, and capturing a separate image for each light source turned on. An image capturing method characterized by: