Optics: measuring and testing – By shade or color – Trichromatic examination
Reexamination Certificate
2002-11-07
2004-08-31
Evans, F. L. (Department: 2877)
Optics: measuring and testing
By shade or color
Trichromatic examination
C356S425000, C250S226000, C209S581000
Reexamination Certificate
active
06784996
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application relates to and claims priority to corresponding Japanese Application No. 2001-344429, which was filed on Nov. 9, 2001, and corresponding Japanese Application No. 2002-246060, which was filed on Aug. 27, 2002.
RELATED APPLICATIONS
This application relates to and claims priorities from corresponding Japanese Patent Application No. 2001-344429 filed on Nov. 9, 2001 and Japanese Patent Application No. 2002-246060 filed on Aug. 27, 2002.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a color sorting apparatus for sorting out colored granular objects or foreign objects which have been mixed into the raw granular objects such as grains or resin pellets, and more particularly to an optical detection device for use in such color sorting apparatus.
2. Description of the Related Art
A conventional known color sorting apparatus of this kind is so constructed that raw granular objects supplied from an upper portion of an inclined flow chute flow down on the flow chute; light is irradiated on the granular objects which are released from a lower end of the flow chute along a falling locus A; light obtained from each granular object arriving and passing at an optical detection position is detected by an optical sensor; and the colored granular objects or foreign objects are determined based on the detected signal and removed from the remaining acceptable granular objects. As the above optical sensor, used is a CCD linear sensor which utilizes the three primary colors of RGB (Red, Green and Blue) for the detection of the colored granular objects (hereinafter referred to as a “color CCD linear sensor”).
The color CCD linear sensor includes the following types. As a first type, as shown in
FIG. 10
, a CCD linear sensor
100
having a filter which allows only the red (R) wavelength to pass (hereinafter referred to as “R-CCD linear sensor”), a CCD linear sensor
101
having a filter which allows only the green (G) wavelength to pass (hereinafter referred to as “G-CCD linear sensor”) and a CCD linear sensor
102
having a filter which allows only the blue (B) wavelength to pass (B-CCD linear sensor) are independently arranged. In
FIG. 11
, there is shown a modified arrangement in which a dichroic mirror
103
is provided to cause the reflected and transmitted light to enter the respective R-, G- and B-CCD linear sensors
100
,
101
and
102
.
As a second type, as shown in
FIG. 12
, there is another arrangement in which the R-CCD linear sensor
100
, the G-CCD linear sensor
101
and the B-CCD linear sensor
102
are arranged vertically in three rows.
As a third type, as shown in
FIG. 13
, there is an in-line type CCD linear sensor
104
in which a light receiving element
104
a
with a filter permitting the passing of only the red (R) wavelength, a light receiving element
104
b
with a filter permitting the passing of only the green (G) wavelength and a light receiving element
104
c
with a filter permitting the passing of only the blue (B) wavelength are sequentially arranged in one row.
However, the above explained conventional CCD linear sensors have the following problems. As for the first type, since three separate CCD linear sensors
100
,
101
and
102
, and the dichroic mirror
103
are necessitated, the dimension and the cost of the optical detection device unavoidably become large and high. As for the second type, the dimension of the device can be more compact than that of the first type because the three CCD linear sensors
100
,
101
and
102
are integrally arranged in three rows. However, to the respective R-CCD linear sensor
100
, G-CCD linear sensor
101
and B-CCD linear sensor
102
, light from the focal points X
1
, X
2
and X
3
which are not on the same optical detection point X but are deviated vertically with one another enters as shown in FIG.
12
. For this reason, with respect to the surface of the granular object which is subjected to the optical detection, the optical detection for the respective RGB wavelengths within one scanning is performed based on the individual focal points X
1
, X
2
and X
3
. For example, from the point where R-wavelength is detected, no detection of G- and B-wavelength data is performed. That is, it has been difficult to obtain the RGB-wavelength data from the entire surface of the object to be optically detected. Therefore, there has been a demand of further improvement in the precision of acceptable and unacceptable detection based on RGB-wavelength data.
As for the third type, since this is a horizontally in-line CCD linear sensor
104
, the dimension of the optical detection device can be made more compact than that of the second type. However, since the structure of the CCD linear sensor
104
is such that, as described above, the filter which allows the passing of only the R-wavelength, the filter which allows the passing of only the G-wavelength and the filter which allows the passing of only the B-wavelength are sequentially arranged in one row, the respective R-, G- and B-wavelengths are optically detected from one side to the other side at the optical detection position X as shown in FIG.
14
. For this reason, with respect to the optically detected surface of one granular object S, for example, the G- and B-wavelengths are not optically detected at the portion where the R-wavelength has been detected as understood from FIG.
15
. Therefore, there has been a demand of further improvement in the detection accuracy on the RGB basis in the same manner as in the above second type.
Therefore, the principal object of this invention is to provide an optical sorting apparatus for granular objects in which the sorting accuracy is enhanced and the cost thereof is reduced.
SUMMARY OF THE INVENTION
According to the present invention, there is provided a color sorting apparatus for granular objects comprising:
a transferring means for transferring raw granular objects to an optical detection area;
an optical detection means arranged around a falling locus of the raw granular objects which are released from the transferring means, the optical detection means comprising a CCD linear sensor, an illuminating means and a background means, the optical detection means functioning to detect light from the background means and each of the granular objects irradiated by the illuminating means, the CCD linear sensor including a plurality of light receiving elements arranged in at least one row, each being capable of detecting red, green and blue wavelengths, and the illuminating means including a red light source, a green light source and a blue light source;
a control means for determining whether a granular object at the optical detection area is an acceptable one or an unacceptable one based on the comparison between the detected light signal received by the CCD linear sensor and a threshold value established in advance, wherein the control means sequentially switches over the red, green and blue light sources while the granular object is passing within the optical detection area, and wherein the CCD linear sensor receives light from the granular object in synchronization with the switching of said light sources; and
a sorting means for removing the unacceptable granular object from the falling locus in response to a rejection signal from the control means.
In the above color sorting apparatus, it is preferable that a condition V≦L/3T is satisfied, wherein T represents a speed of one scanning of the CCD linear sensor, V represents a falling speed of the granular object, and L represents a length of the optical detection area for the CCD linear sensor in the direction of the falling locus.
According to the above arrangement, the red, green and blue light sources are sequentially switched over while the granular object is passing within the predetermined optical detection area and, in synchronization with this switching operation of the light sources, the CCD linear sensor detects the red, green, blue wavelengths from the entire surface of each gra
Ikeda Nobuyoshi
Ikeda Norimasa
Evans F. L.
Satake Corporation
Wells St. John P.S.
LandOfFree
Color sorting apparatus for granular object with optical... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Color sorting apparatus for granular object with optical..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Color sorting apparatus for granular object with optical... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3289610