JP2004310695A - Image distinction sensor with underexposure compensation function - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an integrated image distinction sensor not generating imperfect image pickup by underexposure. <P>SOLUTION: This integrated image distinction sensor has: a solid-state image sensor 24; a lens holder 17 provided with a lens optical system 30 forming an image of a detection object on the solid-state image sensor; and a detection object-irradiating light source surrounding the lens holder or disposed close to the holder. The integrated image distinction sensor is provided with auxiliary light sources 25a, 25b around the solid-state image sensor, and has a diffusible/light-transmissible plate body 29 having diffusibility/light-transmissibility for diffusively radiating light emitted from the auxiliary light sources onto the solid-state image sensor, formed with an aperture 29b allowing the formation of an image forming optical path from the lens optical system to the solid-state image sensor. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image discrimination sensor, in particular, an image discrimination suitable for performing a defect or defective judgment of an object by performing imaging / comparison of a shape of an object moving on a production line or a sticker attached to the object, and mark recognition. It concerns a sensor.
[0002]
[Prior art]
In recent years, it is essential for an image discrimination sensor to use a device for illuminating a target article together with a camera as a means for obtaining a good image (for example, see Patent Document 1). Ring illumination for reducing the number of pixels (for example, see Patent Document 2), and a lighting device equipped with a large number of LEDs (for example, see Patent Document 3) have been proposed.
[0003]
[Patent Document 1]
JP-A-9-259278 (refer to the abstract and FIGS. 1 to 5)
[0004]
[Patent Document 2]
JP-A-2002-319021 (see FIG. 3)
[0005]
[Patent Document 3]
JP-A-10-320538 (see FIG. 2 and FIGS. 6 to 8)
[0006]
On the other hand, in the imaging device, measures such as increasing the number of pixels of the camera in response to high-speed, high-precision requirements, and providing a light diffusion plate in the camera field of view to calibrate the variation in sensitivity of the imaging device are taken. (For example, see Patent Document 4).
[0007]
[Patent Document 4]
JP-A-2002-318200 (refer to the abstract and FIGS. 1 and 2)
[0008]
As described above, since the image discrimination sensor irradiates the target object using the illumination device and captures and processes the reflected light with a solid-state imaging device such as a CCD, image data as good as possible in the imaging is obtained. Obtaining a supreme proposition. However, when imaging conditions are severe, especially when imaging an object moving at high speed on a production line, the above various attempts have not been effective.
[0009]
In an image discrimination sensor that irradiates a target object and captures and processes the reflected light with a solid-state imaging device such as a CCD, a plurality of LEDs of a single color, for example, red, are arranged as an illumination device, and the target is captured and processed. Most of the methods have been established as methods for acquiring two-dimensional information of an object, and the methods described in Patent Literatures 1 to 4 described above are not examples.
[0010]
[Problems to be solved by the invention]
As a first problem of the present invention, in order to adapt the image discrimination sensor to various inspection processes such as a precision production line, a compact integrated type equipped with a light source for illuminating a detection object is required. It is necessary to make the size of the imaging lens system for the solid-state imaging device as small as possible.However, when they are made smaller, the amount of light irradiation on the detection object decreases and the light enters the solid-state imaging device through the imaging lens system. The amount of light to be detected also decreases, and the contrast (S / N ratio) of the detected object image deteriorates. In the case of an object moving at a higher speed, the exposure time becomes shorter as the speed increases, and an output of a level at which the image can be discriminated, which has been obtained at the normal speed, cannot be obtained. This means that absolute output of the image sensor is insufficient, and cannot be solved by sensitivity adjustment in the amplification system.
[0011]
A second object of the present invention is to provide a method for identifying a mark or the like using a luminance difference generated in an object by using a multicolor light source emitting light for each color as a lighting device. The means will be described after describing a plurality of means for solving the first problem.
[0012]
[Means for Solving the Problems]
The basic configuration of the present invention is a solid-state image sensor, an image discriminating sensor including a lens optical system that forms an image of a detection object on the solid-state image sensor, and an auxiliary light source provided around the solid-state image sensor. The solid-state imaging device has a diffusion / light-guiding property for diffusing and irradiating light emitted from the auxiliary light source to the solid-state imaging device, and an opening for passing an imaging optical path from the lens optical system to the solid-state imaging device is formed. Equipped with a light diffusing and light guiding plate.
[0013]
The above configuration eliminates the absolute lack of exposure in the case of high-speed imaging by light that is diffused from the auxiliary light source to the solid-state imaging device via the diffusion / light guide plate, and constantly increases the exposure amount. In addition, light from a detection object (image light input) is made incident on a solid-state imaging device to enable image discrimination.
[0014]
The present invention further includes a detection object irradiation light source surrounding the lens optical system or disposed in close proximity to the optical system, and a cover lens that covers the front end of the lens optical system and the front of the detection object irradiation light source. The cover lens constitutes an integrated image discriminating sensor having a light diffusion function for uniformly irradiating the detection object with light emitted from the detection object irradiation light source.
[0015]
According to the above further configuration, it is possible to prevent a direct ray from a light source for detecting object irradiation incorporated in proximity to an imaging optical axis from forming on the detection object in order to form an integrated sensor. If this is the case, clear images can be obtained without inconvenience that image irregularities such as halation will occur due to light directly reflected from the detection object toward the solid-state imaging device.
[0016]
The present invention also has a housing in which the integrated image discriminating sensor is further assembled with a front panel equipped with the cover lens, a rear panel, and a case member made of a heat conductor covering four side surfaces between these two panels. As the exterior of the integrated image discriminating sensor, a heat conductive heat radiating means having a front part which is heat-transferably joined to the back surface of the light source for detecting object irradiation is housed in this housing, and the heat radiating means is provided. The wing is brought into contact with the inner surface of the case member.
[0017]
The above-mentioned exterior heat radiation structure is that the light source for detecting object irradiation (hereinafter referred to as “main light source”) as the main light source emits a sufficient amount of light. And the integrated image discrimination sensor is prevented from being broken down or abnormal due to a rise in temperature. This is very significant since the detected object should be illuminated with a sufficient amount of light intended for high-speed processing before the aid of the aforementioned auxiliary light source.
[0018]
The present invention further provides an imaging / image processing block comprising a printed circuit board on which a solid-state image sensor and an auxiliary light source are mounted, and a print sensor having a touch sensor interlocked with a display element and setting keys and other user operation means. A user interface block comprising a substrate is provided, and the rear panel has a window for observing a screen of the display element and a surface portion exposing the user operation means.
[0019]
According to the above configuration, the imaging process by the solid-state imaging device is controlled by the imaging / image processing block and image processing is performed for each of the integrated image discrimination sensors. The user can also refer to the display on the display element from the window of the rear panel and use the user operation means to set the image processing result to an optimal state for detecting the defect of the detected object or determining whether the sensor is good or bad. Adjustments can be made accordingly.
[0020]
The present invention further provides a light source for detecting object irradiation, which surrounds the lens optical system or is disposed in close proximity to the holder, in two or more colors in order to solve the second problem described above. By combining the light sources that emit light and sequentially emitting light of each color, the luminance difference between the image when an object or mark or the like of a specific color is illuminated with the light of the specific color and when illuminated with light of another color Is to be detected.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a preferred embodiment of the integrated image discrimination sensor of the present invention will be described with reference to FIGS. As shown in FIGS. 1 and 2, the external structure of the integrated sensor includes a front panel 1 on the front side, a rear panel 2 on the rear side, and a heat source such as a metal covering the four upper, lower, left and right sides between the panels 1 and 2. And a case member 3 made of a conductive material.
[0022]
A main part of the front panel 1 is a cover lens 4 which, when viewed from the front, includes the cover lens 4 and an objective lens inside the sensor and a high-density LED arrangement in the periphery through a filter (described later) disposed immediately after the cover lens 4. The main light source is seen through. On the other hand, a window 5 is formed in the rear panel 2, and a display element 6 in a user interface arranged immediately before the sensor inside the sensor is located in the window 5. The rear panel 2 is further provided with a power and signal line connector terminal 7, a setting key 8 as user operation means, and cursor keys 8a and 8b.
[0023]
FIG. 3 is an exploded perspective view of the integrated image discrimination sensor according to the preferred embodiment. Four female screw blocks 10a, 10b,... For fixing the main light source 9 project from the back surface of the front panel 1, and are inserted into mounting holes provided on the outer edge of the support printed board 11 of the main light source 9. The main light source 9 can be fixedly supported by receiving the screw 12.
[0024]
The high-density LED arrangement 9a of the main light source 9 is an annular array of LEDs having a center opening for inserting a lens holder supporting an objective lens and the like, and the front of the LED arrangement 9a is used to emit light to a detection object. A polarization filter 13 for specifying the polarization direction is provided. The polarization filter 13 has a central opening similar to that of the LED arrangement 9a, and a similar polarization filter 14 having a size corresponding to the central opening is disposed at a position corresponding to the central opening. Thereby, the light emitted from the main light source 9 is linearly polarized at a specific angle by the polarizing filter 13 and hits the detection object, and the light coming from the detection object toward the objective lens can be further changed in the polarization angle by the polarizing filter 14. In this configuration, the direct reflection light from the detection object does not enter and does not disturb the imaging.
[0025]
The case member 3 and the rear panel 2 are integrated by inserting long screws 15 into holes at their four corners and screwing them into corresponding screw holes (not shown) provided on the back surface of the front panel 1. Inside, in addition to the main light source 9 described above, a radiator plate 16 for the main light source 9, an imaging / image processing block 18 including a lens holder 17 including a solid-state image sensor and a substrate to which the lens holder 17 is attached, and the display element 6. A user interface block 19 made of a printed circuit board is fixedly supported.
[0026]
Next, with reference to FIG. 4 and FIG. 5, an internal structure on which a preferable sensor function is performed when the integrated image discrimination sensor of the embodiment is assembled will be described. FIGS. 4A and 4B show the related structure of the LED arrangement 9a of the main light source and the cover lens 4 of the front panel 1. FIG. 4A shows the LED arrangement 9a of the main light source 9 as viewed from the front with only the cover lens 4 covered. It is the figure which looked at, and (b) is the principal part sectional drawing seen along the AA arrow line of the front view (a). The rear surface of the cover lens 4 has a circumferential concave surface so as to face as a concave lens for each LED circumferential array corresponding to the axis of the central opening 21 in the resin holding substrate 20 of the LED arrangement 9a, that is, the radial position from the optical axis. 22a, 22b, 22c are sequentially formed. Therefore, the circumferential concave surface is formed by the number of steps corresponding to the number of LED circumferential arrays.
[0027]
Thus, since the light emitted from each LED is transmitted through the cover lens 4 in a diffuse radial manner, it is possible to prevent the image from being disturbed due to the concentrated irradiation of the detection object and the return of a large amount of directly reflected light. As described above, there are thin polarizing filters 13 and 14 between the cover lens 4 and the LED arrangement 9a to prevent light directly reflected from the detection object from being incident on the image pickup device. The illustration is omitted to avoid complication.
[0028]
FIGS. 5A and 5B show (a) an internal structure mainly including a relationship between the main light source 9 having the LED arrangement 9a and the heat radiating plate 16, and (b) a front surface of the user interface block 19 located behind the heat radiating plate 16 (sensor structure). Are located on the back side. In FIG. 3A, a heat conductive sheet 23 made of, for example, silicon rubber is pressed against the back surface of the support printed board 11 of the main light source 9 for buffering the front part of the heat radiating plate 16. The heat conductive sheet 23 has high thermal conductivity and excellent electrical insulation, has a large contact area with the printed board 11, and is thin, so that the heat generated by the LED can be sufficiently transferred from the printed board 11 to the heat radiating plate 16 body. introduce.
[0029]
The main body of the heat radiating plate 16 is made of a copper plate or the like, which is a good conductor, and its upper and lower wings, which are bent at substantially right angles, are pressed against the upper and lower inner surfaces of the metal case member 3 and the amount of heat received from the printed circuit board 11 is transferred to the case member. Conduction to 3. The case member 3 occupies most of the upper, lower, left and right sides except for the front side and the back side of the sensor structure, has a sufficient surface area, and has an appropriate heat capacity. In addition, the structure and electrical characteristics in the housing are protected from deterioration due to temperature rise, and safety of a user is achieved.
[0030]
As shown in FIG. 5B, the user interface block 19 has a display element 6 for a user monitor arranged so as to be exposed on the window 5 (FIG. 2) of the rear panel 2 and a setting key of the rear panel 2. 8 and touch sensors 8a ', 8b' and 8 'corresponding to the cursor keys 8a and 8b.
[0031]
The underexposure compensation structure of the solid-state imaging device which is the core of the present invention is configured as shown in FIGS. In FIG. 6, a solid-state imaging device 24 is fixed to a substrate of the imaging / image processing block 18, and a pair of auxiliary LED devices 25a and 25b are attached above and below the device 24 in this case. A hole 27 for inserting a screw 26 for fixing a base (holder base) 17a of the lens holder 17 is formed at a position adjacent to the outside of each of the auxiliary LED elements 25a and 25b.
[0032]
When the holder base 17a has four legs having screw holes 28 for screws 26 projecting rearward, and the tips of these four legs are fixed to the substrate surface of the block 18 by the screws (26), the substrate Between the surface and the back surface of the holder base 17a, not only the mounting thickness of the solid-state imaging device 24 but also a further extra space is generated, and the light emitted from the auxiliary LED elements 25a and 25b is transmitted to the solid-state imaging device here. A light guide rubber 29 as a diffusion / light guide plate for diffusing and irradiating 24 is disposed. The light guide rubber 29 has a back surface section covering the solid-state imaging device 24, and a front boss-like portion 29a that enters the back surface opening of the holder base 17a, and furthermore, the lens tube 30 of the lens holder 17 through the boss-like portion 29a and the main body. It has an opening for allowing formation of an imaging optical system from to the solid-state imaging device 24. A wavelength selection filter 31 having desired characteristics is applied to the front of the boss-like portion 29a of the light guide rubber.
[0033]
Thus, an integrated structure obtained by assembling and fixing the components up to the lens barrel 30 to the substrate of the imaging / image processing block 18 is as shown in FIG. As a result, the light emitted from the auxiliary LED elements 25a and 25b enters the light guide rubber 29 and is scattered, and the light reaching the outer surface and irregularly reflected inside the light guide rubber is completely integrated with the inner surface 29b. The light is uniformly diffused onto the solid-state imaging device 24 and illuminated with light. As described above, since the dim light is emitted from the inner surface 29b of the opening of the light guide rubber 29 that allows the detection / imaging optical path sufficiently, as described above, the detection / imaging reaches the solid-state imaging device 24 through the lens barrel 30. It does not affect the signal of the light beam 32 in the optical path.
[0034]
FIG. 8 is a graph showing general light input / electric output characteristics of the solid-state imaging device employed in the sensor structure of the embodiment configured as described above. The horizontal axis is the average light intensity incident on the solid-state imaging device, and the vertical axis is the output signal intensity. When the incident light intensity is in a range from zero to a weak intensity L1, the electric output is from zero to the upper limit of the noise level, In other words, the electric signal becomes unstable in the unstable range up to the start level O1 of the significant signal intensity, and the electric output is changed to O1 corresponding to the incident light intensity only when the incident light intensity changes from the level L1 to the saturation level L2. It becomes a predetermined value within the range of ~ O2. When the incident light intensity exceeds the saturation level L2, the output is saturated at O2 and no longer corresponds to the light input.
[0035]
Therefore, if the light input intensity to the solid-state imaging device is not within the range of L1 to L2, the light input intensity at the noise level or the saturation level cannot be detected no matter how the output gain is adjusted. In the case of the present invention, the light emitted from the auxiliary LED elements 25a and 25b is completely integrated in the light guide rubber 29, and is uniformly dimly irradiated on the solid-state imaging element 24 so as to seep out from the inner surface 29b. A constant light input of a significant light input intensity L1 or more is given, and the imaging light input of the detected object is superimposed on this, so that an image can be reproduced.
[0036]
Further, a well-known optical technology design such as appropriate setting of the main light source 9 and prevention of stray light is adopted so that a bright imaging light input does not easily exceed the saturation level L2. The LED arrangement 9a constituting the main light source 9 is turned on / off at intervals of, for example, 16 milliseconds. In this case, monotone detection is performed, but the LED arrangement 9a is selectively a combination of LEDs emitting two or more colors, such as blue and red, or a combination of one color and white, for example, 16 mm. By sequentially emitting light at intervals of seconds, it is possible to detect an object or a mark of a specific color from the luminance difference between the mark or the like when illuminated with the light of the specific color and when illuminated with light of another color. I can do it.
[0037]
When a mark or the like is identified according to a conventional example, as shown in FIG. 9A, for example, when the character mark “A” 34 in the white background 33 is red, if the illumination is a single wavelength red light, the white background 33 is used. Is substantially equal to the luminance of the character mark 34, and the contrast between the two cannot be obtained. Therefore, the character mark 34 'cannot be recognized at all or hardly recognized with respect to the white background 33' as shown in FIG. The more blurred it becomes.
[0038]
In the embodiment shown in FIG. 10 in the multicolor irradiation of the present invention, first, as shown in FIG. 9 (a, b), first, in FIG. Illumination and imaging with one-wavelength light are performed to store the image data of (b) equal luminance (embedment of a mark on a white background), and then illumination and imaging with blue single-wavelength light are performed as shown in (c). Obtain the luminance difference (white background high luminance / red mark low luminance). Further, when a difference image between the image luminance data of (b) and (c) is obtained, as shown in (d), there is almost no difference in luminance between the illumination with the single red wavelength light and the illumination with the single blue wavelength light. 33 is projected as black as an unnecessary base 33 ", and a character mark 34 having a large difference in luminance between illumination by red single wavelength light and illumination by blue single wavelength light is projected as white characters 34". These processes are performed by the above-described imaging / image processing block 18.
[0039]
Next, when a mark in a white background 33 including a background 35 in the field of view (in this case, a square mark 36 displayed in one corner of the white background 33) is identified by a conventional example, as shown in FIG. When the mark 36 in the white background 33 is red, if the illumination is the single-wavelength red light, the luminance of the white background 33 and the luminance of the mark 36 become substantially equal, and the contrast between the two cannot be obtained. ), The mark 36 ′ is completely unrecognizable with respect to the white background 33 ′, or is so blurred that it cannot be recognized.
[0040]
Therefore, when the object is illuminated with only blue single-wavelength light, a remarkable difference occurs between the luminance of the white background 33 and the low luminance of the red mark 36, and a sufficient contrast can be obtained. However, the image of the background 35 also has low brightness as indicated by 35 'in (c), and it is difficult to distinguish it from the red mark image 36'.
[0041]
In such a case, in the embodiment shown in FIG. 12 of the present invention, first, as in the process of FIGS. 11A to 11C, a red background 33 and a red mark 36 on the red mark 36 in the background 35 in FIG. Illumination and imaging with single-wavelength light are performed to store (b) image data of equal luminance (embedment of a mark on a white background), and then illumination and imaging with blue single-wavelength light are performed and white background as shown in (c). Obtain the luminance difference (white background high luminance / red mark and background low luminance). Further, when a difference image between the image luminance data of (b) and (c) is obtained, as shown in (d), there is almost no difference in luminance between the illumination with the single red wavelength light and the illumination with the single blue wavelength light. The mark 33 has a large difference in luminance between the illumination with the single-wavelength red light and the illumination with the single-wavelength blue light. This is displayed as a white mark 36 from "". These processes are performed by the above-described imaging / image processing block 18.
[0042]
As described above, in the multicolor irradiation of the present invention,
(1) In general, when a mark is detected on a white background of an object by irradiating a single color light, even if the light is irradiated on a mark of the same color and a white background, the wavelength is similarly reflected, and the luminance difference from the white background is substantially reduced. This eliminates the drawback of being buried in a white background image and undetectable because it does not occur. This is a difference image of each luminance of the object due to the irradiation of two colors of light. The target part to be detected from the captured image is as if a mark part having a luminance difference is outlined from a white background (black image) having no luminance difference. This is because only (mark) can be extracted.
(2) In addition, when performing mark detection on a white background of an object from among objects including not only the object but also the background, there is substantially no difference in luminance between the background and the mark or between the white background and the mark. It eliminates the disadvantage that it cannot be detected by being buried in a background image or a white background image. This is a difference image of each luminance of the object by light irradiation of two colors, and is an image taken as if a mark part having a luminance difference was whitened out from a white background (black image) and a background (black image) having no luminance difference. This is because only the target (mark) to be detected can be extracted from among. Since the light irradiated also to the background space is not substantially reflected, and there is no difference in luminance (of the background image) in each case of the irradiation of the red single wavelength light and the blue single wavelength light. , The background becomes a black image as well as the white background.
(3) It is not affected by disturbance light. This is because, when calculating the luminance of the object surface when irradiating red single wavelength light and blue single wavelength light as described above, if there is disturbance light, the absolute value of the luminance itself at each irradiation changes if there is disturbance light. However, if the luminance difference is obtained, the change due to the disturbance light is neglected, and the relative value does not change, so that it is not affected.
(4) By using a solid-state imaging device (such as a CCD) and incorporating it together with illumination means and image processing means (image discrimination means), not only point / line information (one-dimensional information) but also two-dimensional image information can be obtained. Can be easily obtained.
[0043]
【The invention's effect】
As described above, the present invention provides an integrated image discrimination sensor having a lens optical system that forms an image on a solid-state imaging device, in which an auxiliary light source is provided around the solid-state imaging device, and light emitted from the auxiliary light source is used for solid-state imaging. The device is equipped with a diffused and light-guiding rubber plate with an opening that allows the formation of an imaging optical path from the lens optical system to the solid-state imaging device, while irradiating the device with diffused light. Absolute underexposure in high-speed imaging is eliminated, and light (image light input) from the detected object is always incident on the solid-state imaging device with a constant exposure amount, enabling clear image discrimination. It is.
[0044]
The present invention further provides a detection object irradiation light source surrounding the lens optical system or disposed close to the lens optical system, and a cover lens covering a front end of the lens optical system and a front surface of the detection object irradiation light source. Comprising an integrated image discriminating sensor having a light diffusion function for uniformly irradiating the detection object with light emitted from the detection object irradiation light source, wherein the cover lens is close to the imaging optical axis. This prevents direct rays of light from a built-in light source for detecting object irradiation from hitting the detected object so that a clear image of the detected object can be obtained.
[0045]
The present invention further structures an integrated image discrimination sensor in a housing assembled from a front panel having the cover lens, a rear panel, and a case member made of a heat conductor covering four side surfaces between these two panels, Further, a heat conductive heat dissipating means having a front part which is heat-transferably joined to the back surface of the main light source is housed in the housing, and the wings of the heat dissipating means are brought into contact with the inner surface of the case member, A relatively large amount of heat generated by a large number of LEDs as a main light source is dissipated without accumulating, so that the integrated sensor does not fail due to a rise in temperature or cause an abnormality. This proves to be extremely significant since a sufficiently large amount of light should be applied to the detection object in the high-speed processing line.
[0046]
The present invention further includes, in a single housing, an imaging / image processing block, and a user interface block attached with a display element and a touch sensor linked to a setting key or other user operation means, and a rear panel is provided with a display element. Since it has a window for observing the screen and a surface for exposing the user operation means, the image processing by the solid-state image sensor is controlled and the image processing is performed for each of the integrated image discriminating sensors. Is also performed. The user can also refer to the display on the display element and use the user operation means to set the image processing result to an optimal state for the loss of the detected object or the quality judgment, so that the adjustment according to the sensor installation site can be performed. Is what makes it possible.
[0047]
The present invention further provides a light source for detecting object irradiation, which surrounds the lens optical system or is disposed in close proximity to the holder, as a combination of LEDs that emit light in each of two or more colors, and sequentially emits each color. The object or mark, etc. of a specific color is detected by detecting the difference between the luminance of the target image when illuminated with the light of the specific color and the luminance of the target image when illuminated with the light of another color. It is effective in eliminating insensitivity when inspecting an object, and accurately recognizing an image by omitting a change in luminance of an object image due to disturbance light.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an external structure on a front side of an integrated sensor according to a preferred embodiment of the present invention.
FIG. 2 is a perspective view showing an external structure on a back side of the integrated sensor of FIG. 1;
FIG. 3 is an exploded perspective view of the integrated sensor according to the preferred embodiment of the present invention.
FIGS. 4A and 4B show a related structure between an LED arrangement of a main light source and a cover lens of a front panel in a preferred embodiment of the present invention. FIG. FIG. 2B is a cross-sectional view of a main part taken along line AA of FIG.
5A is a cross-sectional view illustrating a relationship between a main light source having an LED arrangement and a heat sink, and FIG. 5B is a front view of a user interface block located behind the heat sink (located on the back side of the sensor structure). FIG.
FIG. 6 is an exploded perspective view of an imaging / image processing block having a lens holder and fixing a solid-state imaging device.
FIG. 7 is a side sectional view showing an integrated structure obtained by assembling and fixing components up to a lens barrel to a substrate of an imaging / image processing block.
FIG. 8 is a graph showing general light input / electric output characteristics of a solid-state imaging device employed in the sensor structure of the example.
FIG. 9 is a schematic diagram showing that, when a colored mark or the like shown in (a) is to be identified by light of the same color according to a conventional example, the mark becomes unclear such that it is hardly recognizable on a white background as shown in (b). is there.
10A and 10B, in the same manner as in the process of FIGS. 9A and 9B, first, in FIG. 9A, the red character mark “A” is illuminated and imaged with red single-wavelength light, and the brightness of FIG. (Embedment of mark on white background) Image data is stored, and then illumination and imaging with blue single wavelength light are performed to obtain a luminance difference (white background high luminance / red mark low luminance) as shown in (c). When the difference image of the image luminance data is obtained, the white background is projected as black as an unnecessary base as shown in (d), and the luminance difference between the illumination by the red single wavelength light and the illumination by the blue single wavelength light is large. It is a schematic diagram which shows that a character mark is projected as a white character.
FIG. 11 shows a conventional example in which a mark in a white background including a background in a field of view is identified, as shown in FIG. For example, since the luminance of a white background is substantially equal to the luminance of a mark, as shown in FIG. 4B, the mark becomes unclear such that the white background is hardly recognizable.
FIG. 12 is a view similar to the process shown in FIGS. 11A to 11C. Illumination and imaging of red light on a white background and a red mark in the background are performed in FIG. (Buried) image data is stored, and then illumination and imaging with blue light are performed to obtain a white background luminance difference (white background high luminance / red mark and background low luminance) of (c), and further, these luminance difference images are obtained. FIG. 4D is a schematic diagram showing that a white background where a luminance difference hardly occurs is darkly projected, and a mark with a large luminance difference is projected as a white mark from the dark white background and the background.
[Explanation of symbols]
1 Front panel
2 Rear panel
3 Case members
4 Cover lens
5 windows
6 Display elements
7 Connector terminal
8 Setting key
9 Main light source
10a, 10b Female thread block
11 Support printed circuit board
13,14 Polarizing filter
16 Heat sink
17 Lens holder
18 Imaging / Image processing block
19 User interface block
20 Holding substrate
21 Center opening
22a, 22b, 22c Circular concave surface
23 Thermal conductive sheet
24 solid-state imaging device
25a, 25b Auxiliary LED element
29 Light guide rubber
30 lens barrel
31 Wavelength Selection Filter
32 Light rays in the detection / imaging optical path

Claims (5)

In a solid-state image sensor, an image determination sensor including a lens optical system that forms an image of a detection object on the solid-state image sensor, an auxiliary light source is provided around the solid-state image sensor, and light emitted from the auxiliary light source is emitted. A diffusing / light-guiding plate having a diffusing / light-guiding property for diffusing and irradiating the solid-state imaging element, and having an opening for passing an imaging optical path from the lens optical system to the solid-state imaging element; An image discrimination sensor equipped with an underexposure compensation function, comprising: The image discriminating sensor according to claim 1, further comprising: a light source for detecting object irradiation surrounding or surrounding the lens optical system; and a light source for front end of the lens optical system and light source for detecting object irradiation. A cover lens that covers the front surface, wherein the cover lens has a light diffusion function for uniformly irradiating the detection object with light emitted from the detection object irradiation light source. Discrimination sensor. The integrated image discrimination sensor further includes a housing that is assembled from a front panel equipped with the cover lens, a rear panel, and a case member made of a heat conductor that covers four side surfaces between the two panels. As the exterior of the sensor, heat-conducting heat-dissipating means having a front part which is heat-transferably joined to the back surface of the light source for detecting object irradiation is housed in this housing, and the wings of the heat-dissipating means are placed in the case. The integrated image discrimination sensor according to claim 2, wherein the sensor is in contact with an inner surface of the member. An imaging / image processing block composed of a printed circuit board having a solid-state image sensor and an auxiliary light source mounted therein, and a user interface composed of a printed circuit board having a touch sensor interlocked with a display element and setting keys and other user operation means. The integrated type according to claim 3, further comprising a block, wherein the rear panel has a window for observing a screen of the display element and a surface portion for exposing the user operation means. Image discrimination sensor. A light source for detecting object irradiation, which surrounds the lens optical system or is disposed close to the holder, is a combination of light sources that emit light in each of two or more colors, and sequentially emits each color, thereby specifying 5. The method according to claim 2, wherein a color object or a mark is detected based on a luminance difference between an image illuminated by the specific color light and an image illuminated by another color light. The integrated image discrimination sensor according to any one of the above items.

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