JP3176330B2 - Color identification method and device using neutral density filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for identifying the color of an object such as glass or synthetic resin, and more particularly to a method and an apparatus which are effective for automatically identifying the color of a glass bottle to be recycled. About.

[0002]

2. Description of the Related Art For example, when collecting and recycling various types of discarded glass bottles, the value of recycled products can be increased by separating them according to the color of the glass and recycling them individually. The glass bottles that are generally distributed include colorless and transparent ones, greenish ones, brownish ones, blue ones, and dark green ones that are almost opaque. For example, it is preferable that a colorless and transparent glass bottle be recycled as a colorless glass product without being confused with a colored glass bottle. In addition, it is preferable to separate the products colored in each color into recycled glass products of the same system color because the raw materials contained therein are different.

For this reason, it is necessary to identify the color of the waste glass bottle in the recovery step and perform separate collection according to the color, and a color identification device is used. Usually, a method is employed in which a glass bottle fed at a predetermined interval is irradiated with illumination light having a predetermined luminous intensity, and transmitted light or reflected light is spectrally analyzed to determine a color. The spectral analysis may be performed by measuring the output intensity distribution in the three primary color light receiving elements.

[0004] However, in the glass bottles in circulation, the shade of the color may be different depending on the kind of the color and the thickness of the material, and when a certain illumination light is applied to the bottle and observed with a camera or the like, the glass bottle is transmitted by each glass bottle. In some cases, the amounts of light are different, and the output of the detection element becomes so small as to saturate or, conversely, is insufficient for the determination, so that accurate color determination cannot be performed. For example, if you adjust the aperture of the camera to a brown bottle, when measuring a colorless bottle, the amount of incident light will be too large and cause halation. Cannot be performed and the color cannot be determined. Also, if the collected waste glass bottle is affixed with a label, has dirt such as mud, or has foreign matter remaining inside, the transmitted light is partially blocked or the color information is diluted There are many. For this reason, to deal with differences in transmittance by using multiple cameras with different exposure levels in the past,
It was necessary to detect the transmitted light amount and adjust the light amount of the light source to an appropriate value.

To solve such a problem, for example,
Japanese Patent Application Laid-Open No. 7-209087 discloses that the brightness of a bottle is measured from an image signal obtained from a light-receiving element, and when the brightness is not within an appropriate range suitable for color determination, the illuminance of the lighting device or the opening of the neutral density filter is determined. An invention is disclosed in which the color is determined after the adjustment and the adjustment within an appropriate range. According to the invention disclosed in the above publication, even when the color densities of the collected glass bottles are different, it is possible to correctly determine the type of color and to send them to appropriate recovery processing steps.

However, according to the disclosed invention, once the transmitted light or the like is measured and the luminance is determined, and the luminance is not within an appropriate range, the illuminance of the illumination light and the opening of the neutral density filter are adjusted and measured again. , Or extra time to adjust the filter opening. Therefore, it may take a long time to obtain the result of the color determination, and it cannot sufficiently cope with a case where high-speed processing is required. Therefore, in practice, several color determination devices corresponding to the type of the object to be processed are arranged in parallel, and individual processing is performed in accordance with the color density and hue of the object, thereby speeding up the processing. In many cases, we responded to requests. In general, a method of arranging an illumination device and a color determination device vertically above and below a device for transporting an object is often employed. In this case, however, a plurality of systems are arranged because the size of the entire device in the height direction is large. Cannot be vertically stacked, and it is difficult to save the installation area.

[0007] The same problem can be seen not only in the separation and recovery of glass bottles, but also in the separation of colored glass products in the production process and the color identification of various synthetic resin products. Needless to say, it is possible to determine the color by observing not only light transmitted through the object but also light irradiated on the surface. In this case, the same request is made as above.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and an apparatus for quickly identifying the color of an object such as glass or synthetic resin. In particular, it is an object of the present invention to provide a method and an apparatus for identifying a color using transmitted light, which method can be applied to automatically identify a color of a glass bottle for recycling.

[0009]

In order to solve the above-mentioned problems, a color identification method according to the present invention uses a neutral density filter composed of a plurality of portions having different transmittances, through which an image of an object is formed. The color of the target object is identified based on light that has been picked up by a color image pickup device and transmitted through any part of the neutral density filter. Further, the object can be a glass bottle supplied sequentially. In addition,
It is preferable that the neutral density filter has portions having different transmittances, which are striped in the moving direction of the object.

In order to solve the above-mentioned problems, a color discriminating apparatus according to the present invention includes an illumination device for irradiating an object with illumination light with a device for transporting the object therebetween, and a light-reducing filter for reducing light transmitted through the object. A color image pickup device that receives light through the light reduction filter is configured by a plurality of portions having different transmittances, the color imaging device detects light transmitted through a plurality of portions having different transmittances in the light reduction filter, The color of the object is identified based on the light transmitted through any of the portions. In addition, it is preferable that the light attenuating filter is obtained by changing light transmittance by depositing Inconel in a stripe shape. Further, a CCD camera can be used as a color imaging device. Further, the transport device may be such as to transport glass bottles sequentially.

According to the color identification method of the present invention, since an image of an object is obtained through a neutral density filter having a transmittance distribution, even if the luminance of the object differs every measurement, any one of the image signals can be obtained. Can be made to exist as a color signal having an appropriate density from which the color can be determined. Therefore, by sequentially performing color determination processing on portions having different degrees of dimming in the video signal, it is possible to accurately identify the color of the target object using only one image. Therefore, there is no need to adjust the light source to optimize the intensity of transmitted light or to adjust the filter opening to adjust the amount of light incident on the camera. Thus, the time required for color determination is greatly reduced, and for example, the color of an object passing at a speed of several tens of meters per minute can be determined.

In particular, when the object is a glass bottle,
By supplying color sequentially at a high speed by the above-mentioned method while the glass bottles are sequentially supplied by a belt conveyor or the like while passing the measurement position, for example, to efficiently and continuously supply color-coded materials in the recycling process of waste glass bottles. You can do it. In addition, a portion where the transmittance changes stepwise is formed in a stripe shape in a region of the dimming filter that is within the visual field of the imaging device, and the dimming filter is installed so that the stripes are parallel to the moving direction of the object. By doing so, even when a label or a foreign substance is attached to the target object, it is possible to include a portion where the color of the target object can be determined in the video, so that erroneous detection is reduced.

The color of the object may be determined based on the reflected light from the surface of the object. In particular, in the case of a transparent object such as glass or a synthetic resin product, a halogen lamp or the like is used. When the transmitted light is observed by irradiating white light from the back side of the object, the accurate color of the object can be easily recognized without picking up the color information of the opaque foreign matter attached to the surface of the object. It goes without saying that, depending on the object color to be identified, colored illumination having a color component whose color is easy to determine may be used.

According to the color discriminating apparatus of the present invention, since the image of the object acquired by the color image pickup device passes through the neutral density filter including a plurality of portions having different transmittances, the image signal is saturated. It is possible to avoid the part where the color judgment is difficult due to being close to the standard or the part where the image signal is too weak to detect the color, and select and use the appropriate part in the video to correctly judge the color of the object. . Since this color determination electronically handles the video signal from the imaging device, it does not require a mechanical operation as in the related art, and enables extremely high-speed processing.

[0015] When a light-attenuating filter in which inconel is vapor-deposited in a stripe pattern to change the light transmittance is used,
Since the deviation of the transmittance due to the color component is small, there is an advantage that the determination of the object color based on the light transmitted through the filter becomes accurate. When a CCD camera is used as a color imaging device, color determination can be performed for each portion of an image by simple processing using a small and lightweight device. Further, if a transport device that sequentially carries glass bottles into the measurement position, and carries out the measurement bottles after the measurement is adopted, it is possible to determine the color of the collected waste glass bottles at high speed and discriminate and supply the bottles to an appropriate reprocessing process for each bottle.

[0016] Further, a light-attenuating filter in which light transmittance is changed by depositing Inconel in stripes has a small deviation in light transmittance due to a color component. Accurate color determination can be performed.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method and an apparatus for determining a color according to the present invention will be described in detail based on embodiments. FIG. 1 is a perspective view showing one embodiment of a color determination device of the present invention, FIG. 2 is a form of a neutral density filter, and FIG. 3 is a flowchart showing the logic of color identification.
In the illustrated embodiment, reference numeral 1 is a lighting device, 2 is a color imaging device, and 3 is a device for transporting an object.

The lighting device 1 includes an appropriate number of halogen lamps 11, a diffuser plate 12, and a DC power supply 13, all of which are housed in a casing (not shown). Halogen lamp 11
Are arranged substantially parallel to the diffusion plate 12, generate stable light rays having a wide wavelength distribution when illuminated by the DC power supply supplied from the DC stabilizing power supply 13, and irradiate the diffusion plate 12 from the back to the whole. . The diffusion plate 12 is made of a milky white acrylic plate, reduces uneven illumination of the halogen lamp 11, generates relatively uniform white light over the entire surface of the diffusion plate 12, and irradiates an external object as a cool surface illuminator. I do.

The conveying device 3 is a conveyor belt 31 having a recess in the center. The glass bottles 32 arranged horizontally are placed one by one in the recessed portion, and are regulated in front of the diffusion plate 12 while being restricted from rolling left and right. Into the measuring position corresponding to.
The glass bottle 32 is illuminated with white light that has been sufficiently homogenized at the measurement position, and the transmitted light that has passed through the glass is projected on a portion of a neutral density filter provided on the wall of the color imaging device 2. The entire portion of the transport device 3 is surrounded in a tunnel shape so as to suppress the influence of external light. The transport device 3 includes an object detector (not shown). When the object detector detects that the glass bottle has reached a position suitable for photographing, an excitation signal is transmitted to the color imaging device 2. Since the photographing of the glass bottle ends instantaneously, the transport device 3 carries out the glass bottle 32 without stopping.

The color image pickup device 2 includes a neutral density filter 21
And a reflection mirror 22 and a color camera 23, which are housed in a casing (not shown) for shielding external light.
The neutral density filter 21 is arranged at a position facing the diffuser plate 12 and projects the light transmitted through the glass bottle 32. The neutral density filter 21 is formed by depositing a metal on a transparent plate, and portions having different light transmittances are distributed in a stripe shape in one filter. In this embodiment, as shown in FIG. 2, portions 41 and 44 having a transmittance of 25% are formed on the upper and lower sides, and a portion 42 having a transmittance of 100% and a portion 43 having a transmittance of 4% are formed therebetween. . The neutral density filter 21 is installed such that the direction of the stripe is parallel to the direction of transport of the glass bottle 32. In addition,
When Inconel is used as the vapor-deposited metal, the original color component contained in the transmitted light does not change during transmission through the neutral density filter because the transmittance difference due to the color component is small, and the color of the glass bottle 32 can be accurately identified. preferable.

The color camera 23 has a CCD device arranged in a plane, and has three primary color components for each pixel and outputs the received light intensity for each color component. When the color camera 23 receives the excitation signal from the transport device 3, the color camera 23 photographs the glass bottle 32 from behind the neutral density filter 21. The color camera 23 is arranged parallel to the direction of transport of the glass bottle 32 so that the color imaging device 2 can be installed in a narrow space beside the transport device 3. By arranging a color camera in parallel with the transport direction, the height of the entire device can be reduced by about 50 cm as compared with a conventional color identification device of the same type. It is also possible to save the installation area by arranging them on top of each other. For example, it has become easy to arrange the lines of a large bottle and a small bottle one above the other. The light transmitted through the neutral density filter 21 is reflected by the reflecting mirror 22 in the vertical direction and is incident on the color camera 23. C
The image signal obtained by the CD element is sent to a color analyzer, where the hue is determined by comparing the intensities of the three primary color components for each pixel. To make the color judgment easier, the direction of the stripes in the image of the neutral density filter 21 projected on the CCD
It is preferable that the scanning directions of the D elements are substantially the same.

In order to determine the hue, the light components of each primary color are compared and determined, so that the signal intensity must be within an appropriate range. However, glass bottles range from colorless and transparent to almost opaque dark green, and the color density differs for each individual. Therefore, for example, when making a color determination based on light transmitted through a transparent glass bottle, it is necessary to accurately determine the hue because the image signal of each color component exhibits saturation characteristics when almost all of the illumination light enters the camera. This makes it difficult to limit the amount of incident light.

On the other hand, in order to determine the hue of glass having a low light transmittance, it is necessary to receive as much light as possible to detect a color component difference using a weak image signal. As described above, it is necessary to obtain and analyze an image in which the amount of incident light is appropriately adjusted by an appropriate neutral density filter corresponding to the difference in color density. If the transmittance of the filter differs depending on the color component, a complex logic is required to perform the correction according to the filter characteristics when performing signal processing. Therefore, select a filter whose transmittance does not depend on the color component. Is preferred.

In the color discriminating apparatus according to the present embodiment, the dimming filter 21 has striped portions having different transmittances as shown in FIG. By selecting the light transmittance of the stripes in the neutral density filter 21 to be a geometric series, it is possible to cope with a wide range of light intensity by providing only three types of portions having different transmittances. When the glass bottle 32 is photographed through the neutral density filter 21, there is a portion having an appropriate light intensity somewhere on the neutral density filter 21 regardless of the color density of the glass, and the hue of the glass can be determined. I have. After all, since the neutral density filter 21 has portions having three types of neutral density, the same effect can be obtained as when three cameras having substantially different aperture values are installed.

Hereinafter, the procedure of color judgment in the color identification apparatus of this embodiment will be described with reference to the flowchart of FIG. While the color identification device is operating (S1), when the glass bottle 32 is carried into the color identification device by the transport device 3 and reaches the measurement position, the object detector detects the bottle and generates an excitation signal (S2). . The color imaging device 23 waits for the excitation signal and photographs the glass bottle 32 from behind the neutral density filter 21 (S3). The image of the glass bottle 32 is formed so as to overlap the neutral density filter 21. The stripe pattern of the neutral density filter 21 is arranged parallel to the axis of the glass bottle 32. In addition, all types of stripes are included in the width of the glass bottle 32 in the video. Therefore, the brightness of the image of the glass bottle 32 changes corresponding to the striped portions having different transmittances in the neutral density filter 21.

Therefore, first, the intensity of the image signal is measured for the portion having the smallest light transmittance, and it is determined whether or not the portion has an output value enough to determine the color (S4). If the transmitted light in this portion is within an appropriate range and the color can be determined, the process proceeds to the color determination step (S9) (S5). The image is moved to measure the intensity of the image signal (S6), and the possibility of color judgment is judged. If it is possible, the process proceeds to the color judgment step (S7). If it is still weak, the image is moved to the portion with the highest light transmittance. Then, the video output is sent to the color determination device to perform color determination (S9).

The color determining device scans the CCD element, accumulates signals for each color sequentially sent in an appropriate portion, and compares the signals for each color component to determine the hue. Since the wavelength dependence of the dimming rate of the Inconel vapor deposition plate used for the neutral density filter 21 is smaller than that of the color glass filter, it is not necessary to change the determination algorithm depending on the color in this embodiment. The positional relationship between the color camera 23 and the neutral density filter 21 may be arbitrary. In particular, if the color camera 23 and the neutral density filter 21 are arranged such that the main scanning direction of the CCD image element and the direction of the stripes of the neutral density filter 21 projected on the imaging surface coincide with each other, Since the sequentially transmitted image signals become the color signals of the same stripe portion, there is an advantage that the calculation in the color determination device becomes easier.

In the color discriminating apparatus of this embodiment, the colorless transparent glass and the light blue glass are mainly determined based on the light transmitted through the 4% transmittance portion of the neutral density filter 21, and the transmittance is 25%.
It is intended to determine mainly green and brown glass in the part of% and dark green glass in the part of 100% transmittance. For example, a colorless and transparent glass material having a particularly high reproduction value can be easily determined because all three primary color components are balanced and strong based on light transmitted through a portion having the smallest transmittance. Also, the determination of a dark green bottle with a small transmittance can be made without switching filters or adjusting the intensity of illumination.
Based on the same image signal acquired in one photographing under the same condition, it can be performed by using light transmitted through a portion having the highest transmittance. However, it goes without saying that the relationship between the color discrimination and the transmittance zone need not be fixed as described above.

If there is a portion where the glass bottle 32 deviates from the neutral density filter 21, the portion shows the characteristic of white light as it is, and by excluding it from the processing target, more accurate color judgment can be performed. If a label or the like affixed to the glass surface remains, that portion is blocked from transmitted light and has no information on hue, so that it can be excluded from processing. The same applies when foreign matter such as mud remains inside and outside the bottle.

The neutral density filter used in this embodiment is 3
Although four striped zones having different transmittance differences are formed, the use of a larger number of transmittance differences makes the switching of the zones complicated, but makes the color determination more accurate. Also, the transmittance can be appropriately selected according to the luminance of the object. Furthermore, if the width of the stripes is further reduced and the number of stripes having the same transmittance is increased, even when objects having different sizes and shapes are mixed and conveyed to the measurement position, one of the stripes is used. Color judgment. Further, the shape of the portion having different transmittance is not limited to a stripe, and an appropriate shape such as a checkered pattern or a polka dot may be selected. If the color determination device knows this shape in advance, it can perform color identification based on this.

The above embodiment relates to a color identification device for separating glass bottles based on color in a waste glass bottle recovery and recycling facility. However, the present invention relates to a device for sorting in a transport process in which many types of products flow. Needless to say, the present invention can be effectively used when it is necessary to identify other devices, such as a device for separating and collecting materials other than glass, based on the colors of the materials. The target material is not limited to a transparent or translucent material such as glass or synthetic resin that can use transmitted light. Even for opaque materials, the reflected light is used to determine the difference in brightness between the materials through a neutral density filter with different transmittances, and color judgment is performed. Can be sorted based on color.

[0032]

As described above, according to the color identification method and apparatus of the present invention, a plurality of dim areas having different transmittances are set within a field of view of a camera by using a special dim filter, so that exposure values differ. A plurality of processing areas are set in an image, regardless of whether an object with a high transmittance or an object with a low transmittance exists on the screen, without having to adjust the aperture, shutter speed, illumination light, etc. each time. The color can be stably identified by the image processing device. As described above, since only one camera and one image processing apparatus are required, not only the equipment cost can be saved, but also the reliability is improved and the maintenance is facilitated. ADVANTAGE OF THE INVENTION According to the color identification method and apparatus of this invention, although the structure is simpler than before, it is possible to determine the object color at an extremely high speed as compared with the conventional one. Will be able to cope with such situations. In addition, the use of the Inconel striped neutral density filter of the present invention enables more accurate identification of various object colors with a single device.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view illustrating one embodiment of a color identification device of the present invention.

FIG. 2 is a plan view showing one embodiment of a neutral density filter used in the present embodiment.

FIG. 3 is a flowchart illustrating an operation procedure in the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Illumination device 2 Color imaging device 3 Transport device 11 Halogen lamp 12 Diffusion plate 13 DC power supply 21 Dimming filter 22 Reflector 23 Color camera 31 Conveyor 32 Glass bottle 41,42,43,44 Zones with different transmittance

Continuation of the front page (56) References JP-A-7-209087 (JP, A) JP-A-61-292027 (JP, A) JP-A-49-131485 (JP, A) JP-A-63-243726 (JP) JP-A-4-275503 (JP, A) JP-A-10-54762 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01J 3/00-3/52 G02B 5/20

Claims (7)

(57) [Claims] 1. A method for identifying a color by causing a light beam transmitted through an object to be incident on a color image pickup apparatus, wherein the transmitted light beam is imaged through a neutral density filter including a plurality of portions having different transmittances. Make the target incident on the device
To form one image with partially different amount of transmitted light
Te, color identification method is characterized in that so as to identify the color of the object based on any of the parts of the said video. 2. The color identification method according to claim 1, wherein said objects are glass bottles supplied sequentially. 3. The color identification method according to claim 1, wherein the neutral density filter has striped portions having different transmittances in parallel to a moving direction of the object. 4. A color discriminating apparatus comprising: an illuminating device for irradiating an object with illumination light across a device for transporting the object; and a color imaging device for receiving light transmitted through the object via a neutral density filter. Wherein the neutral density filter includes a plurality of portions having different transmittances, and the color imaging device
Detecting the light transmitted through different parts of the transmittance in the attenuation filter to form one picture per object, before
A color identification device for identifying a color of the object based on light transmitted through any part of the video . 5. The color discriminating apparatus according to claim 4, wherein said neutral density filter has a light transmittance changed by depositing Inconel in a stripe shape. 6. The color identification device according to claim 4, wherein the color imaging device is a CCD camera. 7. The color discriminating apparatus according to claim 4, wherein said conveying device sequentially conveys glass bottles.