JPH0599632A - Illuminating method for use in measuring object using video camera and illumination system therefor - Google Patents

Abstract

PURPOSE:To enhance workability and efficiency in measuring an object by causing light sources on a group of straight lines arranged within the of 180 deg. rotation from the axis of a video camera to sequentially emit light so as to select an optimum direction of illumination for the range object, and restricting use of the light sources to that direction in performing close illumination of the object. CONSTITUTION:Emitters 12 are provided on diameters by which the lower face of an emitter mounting portion 13 perpendicular to the axis 11 of a video camera 4 forming the center of an illumination system 5 has its circumference divided into sixteen equal parts, the center of the circumference being located at the center point of the mounting portion 13. The group of emitters 12 are made in pairs 12A, 12A, 12B, 12B located on the same straight line and the emitters 12 located on different diameters are sequentially caused to emit light to illuminate an object 1. Then an optimum direction of illumination is selected. Simultaneously only those emitters 12 which are provided along the optimum direction of illumination emit light to perform close illumination of the object 1. Therefore, the variable density characteristics of the object 1 and a background portion 2 appear with double peaks and thresholds are precisely set, whereby the object 1 can be distinctly measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention captures with a video camera an object such as a factory-processed object which is placed on a background portion and is closely illuminated, performs image processing, and positions the object with high accuracy (attached to the object. The present invention relates to an illumination method for measuring an object by a video camera, which performs a gravity center calculation for recognizing and positioning existing marks, shape patterns, etc.) and shape determination, and an illumination device used for the method.

[0002]

2. Description of the Related Art Referring to FIG. 6, an object measuring video camera system is provided with an illuminating device 5 above an object 1 to be measured, which is placed on a stationary table serving as a background portion 2, to illuminate the object 1 in proximity. The system is such that the reflected light from the object 1 and the background portion 2 is captured by the video camera 4, and the input signal of the video camera 4 is image-processed by the image processing unit 6 built in the computer and measured.

The image processing is performed by the video camera 4
The signal from is replaced with data having binary densities of black and white by the binarization process, and only the object 1 is cut out from the entire background portion 2 and the object 1 captured by the video camera 4 and subjected to image processing. .. That is, the method of cutting out only this object 1 is
A “threshold” selection method called a “mode method” is used because of the relationship between processing time and cost. See FIG.
Based on the density distribution of the image captured and input by the video camera 4, a density difference appears between the object 1 and the background portion 2 existing around the object 1, and the density distribution characteristics of both have a bimodal shape. , The double-peaked valley is set as the “threshold value” S, and only the image of the object 1 is cut out and the object 1 is measured.

7 to 10 are used for the above object measurement.
The proximity illumination device shown in is used. That is, the one shown in FIG. 7 is a coaxial illuminating device which gives irradiation light from the light source 8 through the half mirror 9 to the object 1 in the same axial direction as the video camera 4, and the one shown in FIG. 8 is an optical fiber 10 or a ring-shaped light source. 8 is a ring illuminating device for giving a ring-shaped irradiation light to the object 1, and FIG. 10 is a spot illuminating device in which the light source 8 is fixed to two points on a straight line orthogonal to the camera axis 11, and these are known. The example is used in the measurement system of FIG. Reference numeral 20 in the drawing is a reflector.

[0005]

Generally, the object 1 is a factory-processed product, such as a copper pattern on a printed circuit board.
When the surface is a polished object, the surface of the object 1 has a wavy surface that has a microscopic wavy shape in the same direction. Therefore, when the illumination device 5 performs close illumination, the object 1 is irradiated with light. Light entry direction 15 and wavy peak / valley stripe direction 1
If 4 is deviated, there is a phenomenon that the reflection due to the irradiation light is irregularly reflected, and if this irregular reflection occurs, the density distribution due to the video signal from the video camera 4 is disturbed.

Therefore, in the above-mentioned coaxial lighting device and ring lighting device, since the irradiation light is emitted from all directions,
In the case of the object 1 having a wavy surface, the above-mentioned diffused reflection naturally occurs violently, and there occurs a portion where the density distributions of the object 1 and the background portion 2 overlap each other. As shown by the dotted line in FIG. The boundaries of the distribution are obscured, making the selection of the "threshold" S extremely difficult or impossible. Further, since the spot illuminating device has the illuminating point on the diameter with the camera axis 11 as the center, if the direction of the diameter coincides with the line direction of the waveform of the wavy surface of the object 1, the irregular reflection will occur. Extremely low. However, if the two directions are deviated, the same phenomenon as the above-mentioned coaxial illumination occurs.

From the above, in the case of measuring an object on a wavy surface by using the illumination device of the conventional means, if there is the above-mentioned irregular reflection, a complicated signal processing technique is required and the processing time becomes extremely long and the practicality is lost. Therefore, it becomes necessary to match the direction of the irradiation light with the wavy line direction of the object surface as much as possible using the spot illuminating device for processing. Therefore, the operation of changing the position of the light source 8 or adjusting the direction of the object 1 by observing the object 1 based on a special illumination technique and experience is performed every time the object 1 is changed or each processing lot of the object 1 is processed. It is necessary to perform preparatory work, which significantly impairs the workability and measurement efficiency of object measurement with a video camera.
The present invention provides an illuminating method and an illuminating device which solve the above-mentioned drawbacks of the prior art.

[0008]

According to the present invention for solving the above-mentioned technical problems, "in an object on a background portion is closely illuminated, a video camera captures the image, and image processing is performed to measure the object.
A light source is made to exist on a group of straight lines within a range of at least 180 ° rotation about the axis of the video camera, and an illuminating device that sequentially emits light from each of the straight lines is used. An illumination method for measuring an object by a video camera, characterized in that the optimum irradiation direction for an object on a background portion is selected by sequential light emission, and the light emission is limited to the selected optimum irradiation direction to perform proximity illumination of the object. " A first invention characterized by:

As an illuminating device used in the above illuminating method, "at least one light source is present for each straight line on a straight line group within a range of at least 180 ° rotation about the lens axis of the video camera. In addition, the lighting device characterized by a structure provided with a sequential light emitting means for sequentially emitting the light sources on the respective straight lines for each straight line, and a light source limiting means for emitting only the light source at the selected specific position. It consists of the second invention.

As a mode of the above illumination device, light sources are scattered around a circumference centered on the camera axis, and a sequential light emitting circuit and a light source limiting circuit of the light source group are provided, or The irradiation light is a rotation plate supported so as to be rotatable about the camera axis, or a combination of a ring-shaped light emitter and an irradiation light rotation plate having an irradiation light slit capable of rotation stop is used. The structure is such that illumination is performed through the slit, and the selection of the optimum irradiation direction and the limitation of the light source are made respectively.

[0011]

According to the illumination method and the illumination device of the present invention described above,
When an object on the background part is closely illuminated and captured by a video camera, and the image is processed to measure the object, if the object has a wavy surface such as a polishing scratch, the light source position of the illumination is changed with respect to the object. Then, it is possible to select in advance the optimum irradiation direction in which the stripe direction of the corrugated surface and the incident direction of the irradiation light coincide with each other, and illuminate with the light source position limited to the optimum irradiation direction. Therefore, the diffused light reflected by the background portion and the object captured by the video camera is extremely small, and the bimodal density characteristics of the background portion and the object shown by the solid line in FIG. 5 appear. It becomes clear and precise, and highly accurate object measurement becomes possible.

Further, in the above-mentioned illuminating device, since the light source exists in the 180 ° rotation range around the camera axis and has the sequential light emitting means of the light source, the preferable emission direction is sequentially checked by the sequential emission, The detection and selection of the optimum irradiation direction for an object can be performed efficiently and quickly.

[0013]

Embodiments of the illuminating device will be described below in detail with reference to the drawings. First, with reference to FIG. 1 showing the first embodiment, an illumination device 5 is provided between an object 1 to be measured on a background portion 2 of a stationary table and a camera lens 3 of a video camera 4.
In the object measurement system using a video camera for illuminating the object 1 in close proximity to perform high-accuracy position confirmation or shape measurement of the object 1, the illumination device 5 has a center on the camera axis 11 and A light emitter attaching portion 13 having a lower surface orthogonal to the core 11 is provided, and the lower surface which is the facing surface of the object 1 is divided into 16 equal parts on the circumference centered on the center of the attaching portion 13. A light-emitting body 12 serving as a light source is provided on each diameter, and a group of this light-emitting body 12 includes two 12
A12A, 12B12B, 12C12C and the like are paired, and a sequential light emitting circuit that sequentially emits the light emitting bodies 12 having different diameters is provided. Then, the light emitting circuit sequentially causes the light emitters 12A12A, 12B12B, etc. to emit light to illuminate the object 1, and the optimum irradiation direction is detected and selected, and only the light emitter in the optimum irradiation direction emits the object. 1 has a structure that forms close-up illumination.

By using the above illumination device, the optimum irradiation direction for the object 1 can be easily selected by the sequential light emission of the light emitter 12. Then, referring to FIG. 4, the limited irradiation of the optimum irradiation direction causes the irradiation direction 15 and the stripe direction 14 of the corrugated surface of the object 1 to coincide with each other, so that irregular reflection is extremely reduced. The characteristic appears in a bimodal shape and the "threshold value" S is set accurately, and the measurement of the object 1 can be performed very clearly. It is sufficient that at least one light-emitting body 12 exists on the same diameter, and if the light-emitting body 12 is arranged at least at four semicircumferential four-divided positions, it is practically supported as an object measurement of an industrial processed product. There is no.

Next, a second embodiment of the illuminating device of the present invention will be described with reference to FIG. Illumination device 5 of this embodiment
Is an illuminator rotating plate 17 which has an automatic rotation mechanism by a motor 16 and which can be freely stopped.
And a lower surface thereof is provided so as to be orthogonal to the camera axis 11, and a pair of light-emitting bodies 1 are provided on one diameter of the lower surface.
2 is hung to face the object 1, and the light-emitting rotary plate 17 is rotated so that the light-emitting body 12 emits light continuously in succession, and the light-emitting rotary plate 17 is stopped to irradiate in a limited direction. ..

Next, a third embodiment of the illuminating device will be described with reference to FIG. That is, the illumination device 5 of this embodiment is
The ring-shaped light emitter 12 on the camera lens 3 side and the irradiation light rotating plate 18 on the object 1 side are combined.
And the irradiation light rotating plate 18 have their respective centers at the lens axis 1
1 and are arranged on a plane orthogonal to the lens axis 11. And the irradiation light rotating plate 1
8 has an automatic rotation mechanism composed of a motor 16 and can freely stop rotation. Further, a pair of irradiation light slits 19 arranged in a straight line and having a long hole on the diameter thereof are provided, and a light emitting body 12 is provided. The irradiation light of is irradiated onto the object 1 through the irradiation light slit 19. The light-emitting body of this embodiment also emits light continuously, and by stopping the rotation of the rotary plate 18, the optimum irradiation direction can be selected and limited-direction irradiation can be performed.

The detection set of the optimum irradiation direction in each of the above-described embodiments is made by visual confirmation selection by the image of the monitor TV 7 or automatic selection by a computer in the image processing unit 6. In the case of the automatic selection, for example, in the case of the first embodiment, the light emitter 12
A12A, 12B12B ... 12H12H are sequentially emitted, and the concentration distributions of the object 1 and the background portion 2 based on the respective emission are stored, and among them, a light emitter showing a bimodal concentration distribution characteristic shown by the solid line in FIG. Is selected to be the optimum irradiation direction, and only the light emitter emits limited light to illuminate the object,
The object 1 is measured.

[0018]

As described above, the illumination method for measuring an object by the video camera of the present invention and the illuminating device using the same, in measuring an object having a corrugated surface such as a polishing surface, It is possible to easily select the optimum irradiation direction that matches the direction of the corrugations on the corrugated surface to perform limited irradiation illumination, which improves the workability and measurement efficiency of object measurement, and also provides high-quality images with clear image processing. It has the effect of being able to measure objects.

[Brief description of drawings]

FIG. 1 shows an illuminating device according to a first embodiment of the present invention, in which A in FIG.
Is the front view of the basic structure, and B in the figure is the bottom view.

FIG. 2 shows an illumination device according to a second embodiment of the present invention, in which A in FIG.
Is the front view of the basic structure, and B in the figure is the bottom view.

FIG. 3 shows an illumination device according to a third embodiment of the present invention, in which A in FIG.
Is the front view of the basic structure, and B in the figure is the bottom view.

FIG. 4 is a perspective view showing an operating state of the embodiment of FIG.

FIG. 5: Density histogram diagram of video signal captured by video camera

FIG. 6 is a system diagram of object measurement by a conventional video camera.

FIG. 7 is a front view of a conventional lighting device.

FIG. 8 shows a conventional lighting device, in which A is a front view and B is a bottom view.

FIG. 9 shows a conventional lighting device, in which A is a front view and B is a bottom view.

FIG. 10 is a front view of a conventional lighting device.

FIG. 11 is an explanatory diagram of diffused reflection by a conventional lighting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Object 2 Background part 3 Camera lens 4 Video camera 5 Illumination device 6 Image processing part 7 Monitor TV 8 Light source 11 Camera axis 12 Light emitter 13 Light emitter attachment part 14 Wavy surface stripe direction 15 Irradiation direction 17 Light emitter rotating plate 18 Irradiation light rotating plate 19 Irradiation light slit 20 External computer S threshold

Claims (2)

[Claims] 1. An object on a background portion is closely illuminated and captured by a video camera, and when the object is image-processed and the object is measured, the axis of the video camera is centered at least 180 °.
Optimum irradiation of an object on the background by pre-sequential emission of the light sources by using a lighting device in which light sources are present on a group of straight lines within the range of rotation and the light sources on the respective straight lines sequentially emit light. A lighting method for object measurement by a video camera, characterized in that a direction is selected and light emission is limited to the selected optimum irradiation direction to perform close-up lighting of the object. 2. At least one light source is present for each straight line on a group of straight lines within a range of at least 180 ° rotation about the lens axis of the video camera, and the light sources on each straight line are respectively 2. The illuminating device used in the illuminating method according to claim 1, wherein the illuminating method has a structure having sequential light emitting means for sequentially emitting light for each straight line and light source limiting means for emitting light only from a light source at a selected specific position.