JP4030570B2 - Image processing light irradiation apparatus and image processing light irradiation method - Google Patents

Description

  The present invention relates to an image processing light irradiation apparatus and the like that are suitably used for surface inspection of products, mark detection, and the like.

  Conventionally, when a product or the like (work) is automatically inspected for scratches, mark detection, symbol reading, etc., the work is imaged with an imaging device such as a CCD camera to obtain image data. Image processing such as digitization (monochrome) is added to automatically discriminate the scratches and symbols. At that time, the work is irradiated with light according to the purpose of the image processing.

  As one example, there is known one that is capable of detecting defects such as scratches by irradiating light with low directivity from the surroundings (hereinafter referred to as low angle light) (Patent Document 1, FIG. 3 and the like). According to such illumination, when the surface is mirror-like, when observed from the direction perpendicular to the surface (imaging direction), light is scattered only at the defective part, and only that part appears to shine. Therefore, the defect can be detected.

In addition, for example, it is possible to irradiate parallel light or light that is almost parallel (hereinafter referred to as coaxial parallel light) from substantially directly above the workpiece, that is, from substantially the same direction as the imaging direction, so that mark detection and symbol reading can be performed smoothly. In addition, there are known ones that change the color of the irradiated light and allow only a specific color printed on the surface of the workpiece to be lifted and read.
Japanese Patent Laid-Open No. 10-21729

  Conventionally, in this type of light irradiation, settings related to light irradiation conditions such as work brightness and light irradiation angle are set only at the initial stage of installation, at the time of maintenance, when the work model is changed, or when a problem occurs, for example, image processing Actually, it is done manually by trial and error using the results. And it is no exaggeration to say that the dynamic and automatic light irradiation condition control during running is not actually performed to the extent that FB control is performed to keep the light amount of the light source constant.

However, when inspecting a workpiece having fine streak-like eyes uniformly on the surface, such as a metal forging shown in FIG. 9 , light is scattered by the eyes depending on the irradiation direction of low-angle light. It may happen that the surface inspection or the mark reading cannot be performed due to the shadow or shadow.

  Of course, for a single workpiece, the operator can perform surface inspection and mark reading by appropriately setting the workpiece installation position and light irradiation direction by trial and error while referring to the image processing results. It is. In addition, for example, in a character reader, there is also known a device that performs retry by appropriately changing the irradiation angle when a character cannot be cut out or read as a result of image processing. However, there is no guarantee that such trial and error settings are optimal.

  Furthermore, for example, when such a workpiece is conveyed on the line and it is necessary to sequentially inspect it, the method described above takes too much time and cannot be dealt with at all. Even if it is configured to automatically determine the result of image processing and automatically adjust the light irradiation conditions, image processing including the automatic adjustment processing still takes a considerable amount of time (several tens of milliseconds). Because of this, quick inspection is not possible.

  Therefore, the present invention does not perform various corrections for image processing on the image processing apparatus side, but the light irradiation state on the workpiece, that is, so that an optimal image for image processing can be obtained on the light irradiation apparatus side, that is, Provided is an image processing light irradiation device that can be said to be an intelligent light irradiation device that dynamically and automatically generates a light irradiation mode while referring to a mode of reflected light from a workpiece, and is described above. This is to solve the problem.

That is, the image processing light irradiation apparatus according to the present invention is used together with an image processing apparatus that processes image information obtained by imaging a predetermined area on a work flowing on a line, and A light irradiation unit that irradiates light so that the irradiation solid angle can be changed from substantially the same direction as the imaging direction, a light state detection unit that detects the brightness of the predetermined region as viewed from the imaging direction, and the light irradiation unit A light irradiation condition control unit that sets a solid angle of light irradiation so that the brightness of all of the predetermined region viewed from the imaging direction is substantially highest or substantially lowest, and the light irradiation unit is laid on the surface A plurality of light emitting elements, wherein the light irradiation condition control unit selectively turns on a part of the light emitting elements to set a light irradiation solid angle. To do.

  If it is such, since it is possible on the light irradiation apparatus side to create the optimal light irradiation conditions for the purpose of image processing, the load such as correction on the image processing apparatus side is greatly reduced. Moreover, since the light irradiation conditions can be set each time prior to image processing, for example, even when inspecting workpieces flowing on the line one after another, an optimal image can be obtained after inspection for each workpiece. it can. Compared to image processing, the detection of light irradiation state and the setting of light irradiation conditions do not require so complicated processing, and the time required is 1 / 10th to 1 / 100th of the image processing time. Time is not a bottleneck, and there is no hindrance to quick inspections. In particular, even if the workpiece on the line is inclined, it is possible to suitably perform defect detection and mark detection by changing the light irradiation angle correspondingly.

In addition, the light irradiation unit includes a large number of light emitting elements laid on a surface, and the light irradiation condition control unit selectively turns on a part of the light emitting elements to emit light. Since the solid angle is set, the mechanical operation mechanism can be reduced as much as possible, and the irradiation solid angle can be changed with a simple configuration.

  As a specific embodiment of the light emitting element, it is desirable that the light emitting element is an LED or a tip portion of an optical fiber having a base end connected to the LED.

The image processing light irradiation method according to the present invention is used for an image processing apparatus that images a predetermined area on a work and an image processing system using the image processing apparatus that processes image information obtained by the image capturing apparatus. The light irradiation unit for irradiating the predetermined area with light so that the irradiation solid angle can be changed from substantially the same direction as the imaging direction is used, and the brightness in the entire predetermined area as viewed from the imaging direction is detected. a light irradiation state detection step of, by controlling the light irradiation unit prior to the image processing, automatic illumination condition setting for setting a radiating solid angle of the light so that the brightness becomes substantially maximum or substantially minimum And the light irradiating unit includes a plurality of light emitting elements laid on a surface, and in the light irradiation condition setting step, some of the light emitting elements are selectively turned on. The Characterized in that it is used to set the radiating solid angle.

For example, in the light irradiation condition setting step, it is desirable that the light irradiation solid angle is set so that the lightness is approximately highest or substantially lowest every time image processing is performed.

As described above, according to the present invention, it is possible to create a light irradiation condition optimal for the purpose of image processing on the light irradiation device side, so that a load such as correction on the image processing device side is greatly reduced. Moreover, since the light irradiation conditions are set every time prior to image processing, for example, even when inspecting works flowing on the line one after another, an optimal image can be obtained after inspection for each work. . Compared to image processing, the detection of light irradiation state and the setting of light irradiation conditions do not require so complicated processing, and the time required is 1 / 10th to 1 / 100th of the image processing time. Time is not a bottleneck, and there is no hindrance to quick inspections. In particular, even if the workpiece on the line is inclined, the defect detection and the mark detection can be suitably performed by changing the light irradiation angle correspondingly. Furthermore, the number of mechanical operation mechanisms can be reduced as much as possible, and the irradiation solid angle can be changed with a simple configuration.

An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1 , the image processing light irradiation apparatus A4 according to the present embodiment images a workpiece holding part A1 that holds a workpiece W having a mirror-like surface, and a predetermined area on the surface of the workpiece W from the facing direction. CCD camera A2 that is an image pickup device that outputs as image data, and image processing device A3 that takes in the image data, performs binarization processing on the image data, and automatically detects a mark or the like engraved on the surface of the workpiece W Thus, the surface inspection system is configured, and a large effect can be obtained when the work W is slightly inclined due to an installation error or the like in the work holding portion A1.

  First, the basic operation of this system will be described. When a substantially parallel light L3 is applied to the mirror-like workpiece surface at an angle that is approximately directly opposite, and when the reflected light L4 is observed, a mark or the like is carved on the surface. Then, in the portion where the surface accuracy is rough, the light L3 is scattered and the reflected light intensity becomes small and is recognized as dark, so that the dark portion can be detected as a mark by contrast with the surroundings.

  Accordingly, the image processing light irradiation device A4 in the present embodiment includes the apparatus main body 1, the control power supply device 2, and the light irradiation state detection unit 6.

The apparatus main body 1 includes a light irradiation unit 4. The light irradiation unit 4 includes a light source 45 composed of a number of LEDs (not shown) and a base end portion connected to each of the LEDs one by one. And a lens 47 (for example, Fresnel) that refracts light L5 emitted from the tip of the optical fiber 46 in a direction orthogonal or substantially orthogonal to the imaging direction in a direction that is parallel or slightly converged. Lens) and a half mirror 48 that directs the light L3 emitted from the lens 47 to the workpiece from the same or substantially the same direction as the imaging direction. As shown in FIG. 2 , the tip of each optical fiber 46 forms a light emitting surface 49, for example, bundled in a matrix, and the light emitting position on the light emitting surface 49 can be changed by changing the LED to be lit. It is made to be able to. Then, by changing the light emission position in this way, the irradiation solid angle of the light L3 with respect to the predetermined region can be slightly changed.

The control power supply device 2 functions as a light irradiation condition control unit. As shown in FIG. 1 , each time the predetermined area is changed, the image processing apparatus A3 refers to the brightness of the predetermined area. Prior to image processing by the above, the light irradiating unit is controlled, that is, the LED to be lit is set, and the solid solid angle of the light L3 with respect to a predetermined region is set so that the lightness is substantially the highest or the lowest It is.

  The lightness is the lightness when the predetermined area is viewed from the imaging direction, and is obtained by measuring the intensity of the reflected light L4 from the predetermined area by the light irradiation state detection unit 6 described at the beginning. ing.

  The light irradiation state detection unit 6 outputs a current or voltage corresponding to the intensity of received light, and uses a dedicated device such as a CMOS camera or a photodiode, for example, and this image processing light irradiation device A4. As a component of Thus, the brightness is obtained from the value of the output signal of the light irradiation state detection unit 6. Specifically, it may be an average value (average value of the entire predetermined area) or an integrated value (total value of the entire predetermined area) of an output signal from a CMOS camera or a photodiode, or an average value or total of a part of the predetermined area. It may be a value. Note that a second half mirror 7 is provided on the optical path of the reflected light L4 in order to guide the reflected light L4 from a predetermined region to the light irradiation state detector 6.

Next will be described the operation of the present system configured to FIG. 3, below with reference to FIG.

When the workpiece W is installed at a predetermined position, as shown in FIG. 2 , the control power supply 2 sequentially turns on the optical fibers 46 on the light emitting surface 49 one by one in the vertical direction (ST10) . At this time, the output signal from the light irradiation state detection unit 6 is received each time, and the position (X position) of the optical fiber 46 when the brightness is the highest from the output signal value is stored (ST11) . Next, the optical fiber 46, the lateral sequentially illuminated in the Y direction by one column (ST12), and stores the position of the optical fiber 46 (Y position) when the most brightness was higher as well (ST13). In the figure, the graph exemplifies the transition of lightness (reflected light intensity) obtained by sequentially lighting the optical fiber 46 in the X direction and the Y direction.

Then, the optical fiber 46 (ON) at the position with the X position and the Y position as coordinates is turned on, and the other optical fibers 46 (OFF) are turned off (ST16) .

By turning on the optical fiber 46 (ON), the irradiation solid angle of the light L3 at which the lightness is substantially maximum is set (ST17) . That is, as shown in FIG. 5 , even if the workpiece W has a slight inclination θ, the solid angle of irradiation of the light L3 is set according to the inclination angle θ, and the reflected light from the workpiece W is always applied to the imaging device A2. L4 is incident as much as possible (ST18) . Of course, various other methods are conceivable, such as setting the optical fiber 46 in which the lightness is substantially maximized by sequentially lighting the optical fibers 46 one by one.

Therefore, for example, when inspecting the workpiece W flowing on the line, even if a part or all of the workpiece W is inclined at the time of installation, for example, the image processing light irradiation device A4 automatically and automatically responds thereto. The irradiation solid angle of the light L3 is changed, and the reflected light L4 from the work W is allowed to enter the imaging device A2 as much as possible without shifting. For this reason, even if the workpiece W is slightly inclined, it is possible to quickly detect a mark or the like formed in the predetermined area as a sufficient contrast difference without imposing a burden on the image processing apparatus A3.

As shown in FIG. 6 , one optical fiber 46 (OFF) may be turned off and all remaining optical fibers 46 (ON) may be turned on. In this case, contrary to the above, the mark or the like can be detected with the contrast because the part with the mark or the like becomes bright and the other part becomes dark. Of course, as in the first embodiment, an illumination mode identification signal indicating which illumination mode is being used is transmitted to the image processing apparatus A3, and the image processing apparatus A3 receives a predetermined threshold value from the content of the illumination mode identification signal. It is necessary to determine whether a portion with higher brightness is detected as a mark or a lower portion is detected as a mark.

In addition, when only one optical fiber 46 is turned on or off, the degree of scattering of the light L3 after passing through the lens 47 near the point light source becomes small, so even the scattered reflection due to slight roughness of the workpiece surface. Can be detected as contrast. However, depending on the purpose, there is a case where it is not desired to detect slight roughness as noise. In such a case, as shown in FIG. 7 and FIG. 8 , the light L3 after passing through the lens 47 is obtained by turning on or off a plurality of optical fibers 46 to obtain a light source having a certain area. The detection accuracy may be lowered by slightly increasing the degree of scattering.

  <Other embodiments>

  The present invention is not limited to the above embodiments. For example, although the LED is used in the embodiment, for example, a semiconductor laser may be used, or another light emitter may be used.

  It is also possible to optimize the light irradiation conditions by changing the light irradiation intensity, irradiation range, and the like.

  Furthermore, although the light irradiation condition control unit is incorporated in the control power supply device in the above embodiment, it may be incorporated in another device, and in the future, the light irradiation condition detection unit and the light irradiation condition control unit have one. An embodiment in which the chip is integrated into the chip is also conceivable. For example, a logic circuit may be mounted on a hardware sensor (for example, a plurality of optical sensors) or the image sensor chip itself, and this may have a function as a light irradiation condition control unit.

  Of course, the present invention is not limited to the above illustrated example, and various modifications can be made without departing from the spirit of the present invention.

  The typical block diagram which shows the whole system in one Embodiment of this invention.   The light irradiation end figure of the optical fiber for demonstrating the method to change the irradiation solid angle in the same embodiment.   The flowchart which shows the system operation example in the embodiment.   The flowchart which shows the system operation example in the embodiment.   The typical block diagram which shows the whole system for demonstrating the method to change the irradiation solid angle in the same embodiment.   The light irradiation end figure which shows an example of the light emission mode of the optical fiber in the embodiment.   The light irradiation end view which shows the other example of the light emission mode of the optical fiber in the embodiment.   The light irradiation end view which shows the further another example of the light emission mode of the optical fiber in the embodiment.   The image figure which shows the workpiece | work which has a streak-like eye.

Explanation of symbols

A2 ... Imaging device (CCD camera)
A3 ... Image processing device A4 ... Light irradiation device for image processing 2 ... Light irradiation condition control unit (control power supply)
4 ... Light irradiation part 6 ... Light irradiation state detection part
L3 : Light W ... Work

Claims (4)

Used with an image processing apparatus for processing image information obtained by imaging a predetermined area on a workpiece flowing on a line;
A light irradiation unit that emits light so that the irradiation solid angle can be changed from the substantially same direction as the imaging direction with respect to the predetermined region;
A light state detection unit that detects the brightness of the predetermined region as seen from the imaging direction;
A light irradiation condition control unit that controls the light irradiation unit and sets a solid angle of light irradiation so that the brightness of all of the predetermined region viewed from the imaging direction is substantially the highest or substantially the lowest ,
The light irradiation unit is provided with a number of light emitting elements laid on the surface,
The light irradiation apparatus for image processing, wherein the light irradiation condition control unit selectively turns on a part of the light emitting elements to set a light irradiation solid angle . The light-emitting element, an image processing light irradiation apparatus according to claim 1, wherein a distal end of an optical fiber connected to the proximal portion to the LED or LED. An imaging apparatus that images a predetermined area on a work flowing on a line, and an image processing system that uses an image processing apparatus that processes image information obtained by the imaging apparatus,
For the predetermined area, using a light irradiation unit that emits light so that the irradiation solid angle can be changed from substantially the same direction as the imaging direction,
A light irradiation state detection step of detecting brightness in all of the predetermined area as viewed from the imaging direction;
A light irradiation condition setting step of controlling the light irradiation unit prior to the image processing, and setting a light irradiation solid angle so that the lightness is substantially the highest or substantially the lowest ,
The light irradiation unit is provided with a number of light emitting elements laid on the surface,
A light irradiation method for image processing, wherein in the light irradiation condition setting step, a part of the light emitting elements is selectively turned on to set a light irradiation solid angle . 4. The light irradiation method for image processing according to claim 3, wherein in the light irradiation condition setting step, the solid angle of light irradiation is set so that the lightness is substantially highest or substantially lowest every time image processing is performed. .