Optics: measuring and testing – By dispersed light spectroscopy – Utilizing a spectrometer
Reexamination Certificate
2001-12-20
2003-12-02
Evans, F. L. (Department: 2877)
Optics: measuring and testing
By dispersed light spectroscopy
Utilizing a spectrometer
C356S330000, C356S310000, C250S22300B, C250S910000, C209S577000
Reexamination Certificate
active
06657722
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an on-line inside-quality inspecting device for non-destructively inspecting and measuring the inside-qualities such as sugar forming degree, acidity, etc. of the objects of inspection, such as agricultural products, by projecting beams of light on each of the objects from one side of it and by receiving and spectrally analyzing, on the other side, the light transmitted through the object while these objects of inspection are in process of being conveyed by various transport means.
BACKGROUND ART
Known methods for measuring the inside-quality of agricultural products include a reflection light method and a transmission light method. In the reflection light method, information on the inside-quality is detected through a reflection light obtained from the agricultural product by projecting beams of light including near infrared rays on the agricultural product. In the transmission light method, information on the inside-quality is detected from light transmittance through the agricultural product of the light projected on the agricultural product.
As disclosed, for example, in Japanese Laid-Open Patent Application No. HE 6-300681,the reflection light method is arranged to be carried out by projecting beams of light including near infrared rays onto a measuring object and by detecting the information on the inside-quality of the object from light reflected by the object as a result of light projection. The method, therefore, permits use of receiving trays arranged in a conventional screening device as they are.
However, the inside-quality information obtainable by the reflection light method is limited to information on a peripheral part and a part near to it of the agricultural product where the projected light is received. Therefore, this method is not applicable to a fruit having a thick skin, although the method is applicable to a fruit having thin skin, such as peaches and pears. In other words, it has been a problem with this method that, in the event of a fruit having a thick skin, the reflection light obtained gives information only on the quality of a thick skin part but does not give any information on the edible flesh part of the fruit.
The applicant of the present patent application has developed and practicalized an inside-quality inspecting device of the transmission light method which is capable of detecting information on the inside-quality of citrus fruits (oranges), melons, watermelons, etc. having thick skin parts and the honey forming parts, or brown scarred parts existing deep inside of apples or the like. The device developed and practicalized by the applicant is arranged, as disclosed in Japanese Laid-Open Patent Applications No. HE 6-288903 and No. HE 10-202205,to use a transport conveyer having agricultural products receiving trays having receiving seats. Each of the receiving seats is provided with a transmitted light passage which vertically penetrates the central part of the seat. The device is thus arranged to have its light receiving part opposed to the lower side of the center part of the receiving tray, so that the device can be used only for the conveyer of the type using such receiving trays. It has been impossible to use the device in combination with any conveyer that is not using the receiving trays of the above-stated type.
Meanwhile, known inside-quality inspecting devices of the transmission light method include a device disclosed in Japanese Laid-Open Patent Application No. HEI 7-229840.In this device, one light-projecting lamp is arranged as a light source on one side of the transport path of a belt conveyer; a light receiving part is opposed to the light-projecting lamp and arranged on the other side of the transport path at a position where an optical path extends horizontally and rectilinearly across the transport path; light is projected sidewise on each agricultural product under inspection; and light which is transmitted through the agricultural product as a result of light projection is detected by the light receiving part. The device is thus arranged to detect the light sidewise transmitted through the agricultural product. However, since the device uses only one light-projecting lamp, the rays of light projected are limited in intensity and quantity. Therefore, in the case of agricultural products having thick skins, the transmitted light has been too weak for spectral analysis and errors in the results of the spectral analysis have degraded the accuracy of measurement.
Agricultural products are naturally grown products. Generally, the inside-quality, such as sugar content, acidity, degree of ripeness, etc. of each product is not uniform and varies according to its parts on the side of having sunlight or on the shadow side thereof. Measurement values obtained by projecting light from the single projecting lamp, therefore, greatly vary and fluctuate depending on the direction of light projection. It has been thus hardly possible to ensure the measuring accuracy of the inside-quality inspecting device. It has been another shortcoming of the device disclosed in the above-cited Japanese laid-open patent application that a large case is necessary for housing it because the device disclosed is arranged to have a diffraction grating directly connected to its light receiving part.
Further, according to the arrangement disclosed, the optical axis of the light-projecting lamp and the light converging axis of a condenser lens of the light receiving part are on one and the same line. Therefore, intense rays of light come to be straightly incident on the condenser lens to bring about some adverse effect on a spectral light receiving element when the optical axis is not blocked by the agricultural product. To prevent the spectral light receiving element from being affected by the intense rays of light under such a condition, a shutter is provided at a light-projecting port. The shutter is, however, arranged to be left open between front and rear agricultural products under the inside-quality inspection while they are in process of transport and is not to be closed and opened for each of them one by one. When the light is not necessary, such as at the time of a pause, the rays of light of the lamp are arranged to be blocked by means of a shutter solenoid. However, although the light from the light-projecting lamp can be thus blocked, fluctuations of ambient light coming into a dark room through the passage of the agricultural product are allowed to come in as they are through the condenser lens to cause the zero level (of a dark current) of the light receiving element. This has been a shortcoming of the device.
Another shortcoming of the device lies in the following point: In order to have the light penetrate through a thick-skinned agricultural product such as oranges, melons, watermelons and the like, with a single lamp used, the lamp must be arranged to have a high degree of output. However, use of such a high-output lamp necessitates some lamp cooling means as it generates a high temperature. Besides, since the light is converged onto the agricultural product by means of a reflection mirror, the light converging part is heated to have such a high temperature exceeding 500 degrees, which has necessitated use of a heat resisting material and presented the hazard of fire. Further, the filament of the high-output lamp is large. The large filament of the lamp not only makes the light converging arrangement difficult but also has a short service life and cannot be used over a long period of time without lowering the illuminance of the lamp.
If the quantity (intensity) of the projection light is increased to have the transmission light sufficiently obtainable even from inspecting objects which do not readily transmit light, the operational amplifier of a spectral analyzer tends to overflow to make the spectral analysis impossible for inspecting objects which readily transmit the projection light.
Further, the operating state of an on-line inside-quality inspecting device varies with variations in t
Evans F. L.
Geisel Kara
Kabushikaisha Kajitsuhihakaihinshitsukenkyujo
Reed Smith LLP
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