MXPA96000339A - Classification machine using detectoresempareda - Google Patents

Abstract

The present invention relates to a sorting machine that has an optical observation station through which a stream of observed products passes through to be classified using a plurality of defined light frequency spectra, comprising: illumination means to brightly illuminate the current of products in the optical observation station in a wide band light spectrum, a plurality of photo-optical detectors positioned to receive light reflected from the observed products, the reflectivity varying respectively in the broadband light spectrum depending on the respective color of the observed products, each photo-optical detector of said plurality of photo-optical detectors including: a first photosensitive device that responds to a first color frequency spectrum in a broadband light radiation signal, said first photosensitive device enabling the at least partial step of the signal to broadband light radiation at longer wavelengths, and substantially not responding to the longer wavelengths, a second photosensitive device walled behind and aligned optically with said first photosensitive device, which responds to a second frequency spectrum of color longer in wavelength than the first frequency spectrum, and a multiple-peak optical filter in front of said photosensitive devices to pass a first defined frequency spectrum of light within said first color frequency spectrum and a second spectrum of light frequency defined within said second color frequency spectrum, said first photosensitive device producing an output that is proportional to the light radiation in the first defined light frequency spectrum, said second light-sensitive device producing an output that is proportional to light radiation in the second frequency spectrum of defined light; and electronic processing means connected to said photo-optical detectors to produce an ejection signal as determined by the presence of at least one predetermined combination of the first and second device outputs.

Description

CLASSIFICATION MACHINE USING SANDWICH DETECTORS INVENTORS: CALVIN GEORGE GRAY and JEFFERY STANLEY PAWLEY, both citizens of the United States, residing respectively at 12322 Wittington Drive, Houston, Texas 77077; and 4703 Torrington Court, Sugarland, Texas 77479, both in the United States.

CAUSAHABIENTE: ESM INTERNATIONAL, INC., A company of the United States, with address at 9800 Townpark Drive, Houston, Texas 77036, United States.

BACKGROUND OF THE INVENTION Field of the Invention This invention relates to sorting machines that optically classify or separate non-standard fungible objects from standard objects when passing through an observation station, by observing such objects in at least two different frequency and frequency spectra. particularly those sorting machines that use detector elements composed of two or more different photosensitive devices. Description of the Prior Art A typical sorting machine of the type which uses the present invention can be a gravity-fed channel sorting machine or a band sorting machine which passes a stream of objects or products to be sorted through a sorting station. optical observation. Typically, the stream comprises standard consumable agricultural products, such as coffee beans, tomatoes or the like, which are known to be of a standard color or tone in at least two bands of the frequency spectrum. However, if a product has been aged, damaged, or is of a different grade from the standard, it will have a non-standard shade or color on at least one of the two bands for which standard products have a known standard color or shade. Such non-standard products can be detected and removed or ejected from the stream by optical devices placed in front of an observation station through which the product stream passes. A sorting machine may have a plurality of parallel channels or paths, each of which with its own optical observation station. Moreover, each optical observation station can have more than one optical sensor device. For example, it is desirable to observe the products or objects from different angles so that a hidden point of view when viewed from a first angle is not hidden from view when viewed from a second or third angle. However, for purposes of simplicity, each stream of products in the channel or path can be considered as a continuous movement of individual products passing through a simplified optical observation station. An optical observation station includes one or more lights to illuminate the products in the stream. An illuminated product reflects light and other frequencies, which are detected by properly placed photosensitive devices to monitor the predetermined standard frequency spectra discussed above. When a reflection is detected as being below a predetermined threshold value in one of the predetermined standard frequency spectra, an ejection device, such as a strategically placed air jet or a mechanical ejection finger, is enabled and subsequently activated when the non-standard product is placed opposite the ejection device. As an alternative to the above operation, the detector can be adjusted to operate the ejector when a reflection considered as non-standard is over a predetermined threshold value in one of the predetermined standard frequency spectra. In this case, the standard products would pass as their reflections would be below the threshold values. It is common in the prior art to use photodetectors or multiple optical detectors for each spectrum, one for each pixel or photosite in a grid of an observation window.

One such system is like that described in U.S. Patent No. 5,062,532, issued November 5, 1991, in the name of George A. Zivley, which was assigned to the assignee hereof. The R 0256K arrangement of photodiodes manufactured by EG & amp;G Reticon is suggested in said patent to implement the invention described therein. However, the exemplary photodiodes of this arrangement are wide-aperture linear devices used in monochromatic or frequency spectrum classification. The invention described in the aforementioned patent is not limited to monochromatic classification, but it is clear that if bichromatic classification were involved, first and second arrays with photodiodes tuned to their respective frequency spectrums would have to be separated from each other, thereby complicating the trigger of the ejection to distinguish which arrangement was involved in a sub-standard product detection. Moreover, the lighting sources of the observation station would have to be more numerous. U.S. Patent No. 5,265,732, issued November 30, 1993 in the name of William C. Long, which was also assigned to the assignee hereof, utilizes a detector that allows the detection of multiple spectra in a single place. An outline of the prior art is shown there using a beam splitter and two filters, one for each of the two frequency spectra used in the classification. The patent also reveals the use of narrow band lights to illuminate products in the product stream, rather than ordinary broadband, general illumination bulbs. In such a scheme, either a beam splitter and appropriate filters are used with the light sources or the light sources are shown at different angles, still requiring appropriate filters. In all cases, the schemes use many different and complex optical devices and the space requirements to implement such schemes are a fundamental consideration. Therefore, it is a feature of the present invention to provide an improved photo-optical detector for use in a sorting machine having a sandwich of at least the first and second photosensitive materials that pass a spectrum of multiple peak frequencies, composite, with a single Multiple optical peak filter (or a set of multiple optical components) in front of the sandwich to pass at least two spectra of defined light frequencies, one within the sensitivity of the wide frequency of the first photosensitive material and the other within the sensitivity of the wide frequency of the second photosensitive material. It is still another aspect of the present invention to provide an improved photo-optical detector of the type described above in which a first photosensitive material is silicon and a second photosensitive material is germanium. It is still another aspect of the present invention to provide a sorting machine using a sandwich detector of the type generally described above which also includes electronic processor means such as a microprocessor to develop a signal for each device separate from the sandwich or, alternatively, a signal when it exists a selected combination of signals from separate devices so that the ejection of a non-standard product can be made based on the existence of the single device signal or one or more selected combinations of signals. It is still another aspect of the present invention to provide an improved photo-optical detector of the type generally described above utilizing a sandwich of multiple photosensitive materials. It is still another aspect of the present invention to provide a sorting machine which utilizes a sandwich photo-optical detector having more than two material devices, a filter having more than two spectral sensitivities of defined light frequencies, and electronic processing means for selecting one or more combinations of signals from the various devices to activate an ejector to remove non-standard products from a stream of products that is being classified. Brief Description of the Drawings In order to be able to understand in detail the way in which the objectives are achieved, aspects and advantages of the invention pointed out above, as well as others that will be evident, will have a more particular description of the invention briefly summarized briefly by reference to its exemplary preferred embodiments illustrated in the accompanying drawings, which form part of this description. However, it should be noted that the drawings illustrate only typical preferred embodiments of the invention and therefore should not be considered limiting of their scope because the invention can admit other equally effective embodiments. In the drawings: Figure 1 is a side view of an electro-optical sorting machine incorporating the sandwich detectors and electrical processing means according to the present invention. Fig. 2 is a top view of an optical observation station of an electro-optical sorting machine, as shown in Fig. 1. Fig. 3 is a side view, in cross section, of a sandwich detector in accordance with Figs. with the present invention. Figure 4 is a diagrammatic, schematic representation of a simplified version of the classification activity according to the present invention. Figure 5 is a typical illustration of responsibility for the sandwich detector shown in Figure 3. Figure 6 is a transmission illustration for the multiple-peak optical filters employed in the present invention. Figure 7 is a diagrammatic representation of multiple sandwich detectors and multiple peak optical filters according to the present invention. DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, and first to FIG. 1, there is shown a high-speed sorter for separating non-standard products or consumables from a flowing stream or flow of such products. Generally, the machine 10 includes one or more slides or slides 12 at an inclined angle, generally of more than 45 ° and preferably almost vertical, of the order of 80 °. The channels are held in position by a frame 14 and are fed by gravity with the product to be classified at the top by means of a hopper 16 attached to the same frame. The product is fed from the hopper 16 through a vibrating feeder that divider 18 to the channels 12. Although a commercial machine usually has two or more channels 12 that operate simultaneously with respect to the products flowing respectively through them, for simplicity of discussion, the machine 10 is hereinafter analyzed as if it included only one channel 12.

Moreover, a band sorter having one or more paths for the product machine can be employed using the invention, if desired. Such a machine has a horizontal band that moves on which the products are deposited to be classified, the band moving through an optical observation station in the form of a channel sorter. The products to be separated or sorted by the machine 10 are small consumable items, such as coffee beans. The coffee beans, as will be appreciated, are individually identifiable by the color in one or more spectral bands. The feeding of the hopper via the vibratory feeder and down through the channel occurs in all cases by gravity. The flow of the products only reduces their speed of free fall by the friction caused by the bands and the surfaces of the trajectory. However, the products are moved at a great speed and in large quantity, as is well known in the art. An optical observer or sensor 20, described in more detail below, is located towards the bottom of the channel. As the product flow passes beyond the sensor, non-standard or sub-standard products are detected. It will be appreciated that such detection requires that sub-standard products be distinguished from both standard and background products. Typically, a sub-standard article, such as a coffee bean, is detectable on the basis of being darker or lighter or of a different color or shade from an acceptable range of darkness, clarity or color, predetermined. for standard or acceptable items. This detection can be in a single spectral range for monochromatic detection, in two separate spectral ranges for bichromatic detection, or in a plurality of spectral ranges for multi-chromatic detection. It will be understood that a "spectral range" may be totally or partially in the visible spectrum or may be totally or partially in the non-visible spectrum. For example, detection is commonly performed in the infrared range. When a sub-standard product or article is detected, an electrical signal is produced which results in an ejection of the sub-standard article by the actuation of an ejector mechanism. An ejector 36 located below and adjacent to the optical sensing means 20 is driven by the aforementioned electric drive signal to produce an air jet to remove the undesirable sub-standard product from the flow of products in the product stream. The ejector can be a mechanical ejector, if desired. When the drive signal occurs, typically, a solenoid valve is operated to release or emit an air jet in the product stream to timely remove the sub-standard article. The delay in the actuation is very short following the time of detection, the synchrony being such as to produce the desired ejection of the detected sub-standard article and is achieved in a manner well known in the art. The articles removed in this way in the process fall down towards the reject accumulator 28 for later disposal. Items not withdrawn continue down the channel 30 extension to be collected or packaged as quality products that pass preset standards and avoid recall. Flow control and sensitivity of the sensors are controlled by preset controls that are well known in the art. Referring now to Figure 2, the observation or optical sensor and related components of the machine are illustrated as seen from above. The sensor means 20 is generally a ring-like structure with a central opening 32, the flow of the products to be separated or sorted, as discussed above, passing through the opening in a "window" location or plane. This is the electro-optical observation station for the machine. The optical or observation mechanism is well known and generally includes three individual sensors spaced peripherally in an equidistant manner., which include a photocell, a photodiode or another photo-optical detector. At least three lamps 38 are included in the plane, one for each individual sensor. Each lamp 38 projects a beam against a separate bottom plate 40, the reflection thereof and any products flowing between the bottom plate and the photocell sensor being detected by the sensor. The reason why three sensors are used is to ensure that a sub-standard item is detected that is detectable from a single address and not necessarily from another direction. Only one lamp 38 is shown for each observation combination constituted by the photocell sensor 37 and the bottom plate 40. In actual practice, there are usually multiple lamps 38 to uniformly illuminate the product stream and the same or additional multiple lamps for illuminate the bottom plate evenly. Figure 3 illustrates a silicon / germanium 51"sandwich" detector, identified as J16 Si series, manufactured by EG & amp;; E Judson of Montgomeryville, Pennsylvania, United States. Of course, any other two or more element devices having similar semiconductor materials similar to such a device may be employed. This two-color detector consists of a high-performance silicon photodiode device 50 mounted in a "sandwich" configuration on a germanium photodiode device 52. It will be seen that the radiation enters the window 54 to cause a nominal response in the the silicon device 50 to 800 nm. The larger radiation wavelengths pass through the silicon material and cause a nominal response in the germanium device 52 at 1,300 nm. In fact, the responsiveness of the two devices is represented more precisely in Figure 5, each device being somewhat broadband over a frequency spectrum. The J16 Si detector has been used in optical fiber power measurements and in two-color temperature detection applications. The manufacturer states that each silicon device or element and the germanium device or element requires a pre-amplifier in practice, which is connected respectively to terminals 56 and 58. A very simplified schematic representation of the essential parts of the invention is shown in Figure 4. The products 59 pass through the optical observation station and are illuminated by one or more light sources 61. Typically, a light source is an incandescent or broadband fluorescent light. The radiation reflections of the products pass through an observation window 63 to be received by a twin-peak optical filter 65 placed in front of the sandwich detector 51. The optical filter 65 has transmission properties such as those shown in the figure 6, where the percentage of transmission is defined in two peaks, namely peak 69, centered at 0.68 nm (600 nm) and peak 71 centered at 1.55 nm (1,550 nm). The first of these peaks is located in the broad spectral response range of the silicon device 50, as shown in FIG. 5, and the second of these peaks is located in the wide spectral response range of the germanium device 52. Transmission response peaks are not normally of the same value, although this may be the case. Returning to Figure 4, the device 50 is connected to a preamplifier / amplifier 60 and the device 52 is connected to a preamplifier / amplifier 62 to produce the outputs which are then subjected to threshold detection in the threshold detectors. 64 and 66, respectively. As the transmission response peaks are not necessarily equal, the threshold detection levels can be set at different levels, as shown in Figure 6. That is, the level can be set at a nominal value of 60 for the first peak that has a lower peak than the second peak, while the threshold level can be set to 80 for the second peak. In operation, an effective signal 68 is produced from the detector 64 when the interpreter means of the classifier determines that a threshold level has been exceeded by the input to the detector 64 and an effective signal 70 is produced from the detector 66 when the interpreter means of the classifier determines that a threshold level has been exceeded by the input to the detector 66. In fact, the interpreter means of the classifier are typically located in a later microprocessor, but the threshold level development scheme and signal production can be understood better from the functional operation of figure 4 that has just been described. The signals 68 and 70 are used in suitable electronic processing means, typically a microprocessor, to result in the eventual ejection activation signal, as previously discussed and which is well known in the art. Perhaps the simplest logical operation of such processor means is to cause an eject activation signal when any of the signals 68 and 70 occurs., the logic can be set to cause an ejection signal only when both signals are present. As previously mentioned, it is common to observe the product stream from multiple angles, such as those illustrated diagrammatically in Figure 7. In this diagram, three sandwich detectors 51 are located at positions at 120 ° from the product stream when viewed from above. Each detector 51a, 51b and 51c is associated with similar related components, such as those discussed in relation to Figure 4, although not all components are shown in Figure 7. In any case, six inputs are applied to the microprocessor 80, knowing the inputs 68a and 70a of the detector 51a, the inputs 68b and 70b of the detector 51b, and the inputs 68c and 70c of the detector 51c. The microprocessor can be programmed to result in an ejection signal 81 when any of the six inputs is present or when any combination of the six inputs is present. An additional possibility for further color discrimination is available when one or more of the optical filters 65a, 65b and 65c has different peak transmission properties.

For example, as shown in Figure 6, an optical filter may have the previously discussed properties, namely with peaks 69 and 71, while another optical filter may have a peak 69a centered at 0.84 nm (840 nm). Also, the threshold level of operation may be different for such a peak, as previously discussed. Moreover, such a filter may have a second peak at the same or different place with respect to peak 71, such as 71a, but its transmission response may be different from that of peak 71, which would imply a different level of threshold operation. In this way, each observation angle can have different frequency response signals that are the same or equal. If more than one detector 51 and related components are placed in each observation angle, then the additional color discrimination operation may be selected in the manner previously discussed. Optional, additional embodiments may be selected using detectors 51 having more than two semiconductors with spectral ranges of general responsiveness different from each other and using optical filters 65 having more than two peaks. However, the general principles of operation are applicable, as discussed above, even when the available combinations are more complex. In this way, although various embodiments have been discussed and other embodiments have been described in a general manner, it will be understood that the invention is not limited thereto, as many modifications may be made, which will be apparent to the technicians in the matter.

Claims (8)

1. CLAIMS 1. A photo-optical detector that includes a first photosensitive device that responds to a first spectrum of color frequencies in a wide-band light radiation signal, said first photosensitive device allowing at least partial passage of the radiation signal of broadband light of greater wavelengths, and not substantially responding to the longer wavelengths, a second photosensitive device walled behind and optically aligned with said first photosensitive device, which responds to a second spectrum of color frequencies of greater wavelength than the first frequency spectrum, and an optical filter of multiple peaks in front of said photosensitive device to pass a first spectrum of defined light frequencies within said first spectrum of color frequencies and a second spectrum of light frequencies defined within said second spectrum of color frequencies, said first device photosensitive sensor producing an output that is proportional to the light radiation in the first spectrum of defined light frequencies, said second photosensitive device producing an output that is proportional to the light radiation in the second spectrum of defined light frequencies.
2. 2. An optical sorting machine having an optical observation station through which a stream of observed products passes to be classified using a plurality of defined light frequency spectra, comprising illumination means to brightly illuminate the product stream in the optical observation station over a wide band light spectrum; a plurality of photo-optical detectors positioned to receive reflected light from the observed products, the reflectivity varying respectively over the broadband light spectrum depending on the respective color of the observed products, each photo-optical detector of said plurality of photographic detectors. optical elements including a first photosensitive device that responds to a first spectrum of color frequencies in a wide-band light radiation signal, said first photosensitive device allowing at least partial passage of the broad-band light-radiation signal of optical wavelengths. larger wavelengths, and not responding substantially to the longer wavelengths, a second photosensitive device sandwiched behind and optically aligned with said first photosensitive device, which responds to a second spectrum of color frequencies of greater wavelength than the first spectrum of frequencies, and a multiple peak optical filter s in front of said photosensitive device for passing a first spectrum of defined light frequencies within said first color frequency spectrum and a second spectrum of light frequencies defined within said second color frequency spectrum, said first photosensitive device producing an output that is proportional to the light radiation in the first defined frequency spectrum of light, said second photosensitive device producing an output that is proportional to the light radiation in the second defined spectrum of light frequencies; and electronic processing means connected to said photo-optical detectors to produce an expulsion signal determined by the presence of at least one predetermined combination of the outputs of the first and second devices.
3. 3. An optical sorting machine, according to claim 2, wherein said first and second defined light frequency spectra are equal for each photo-optical detector.
4. 4. An optical sorting machine, according to claim 2, wherein said first and second defined light frequency spectra are not the same for each photo-optical detector.
5. 5. A photo-optical detector, which includes a silicon device that responds to a first spectrum of color frequencies in a wide-band light radiation signal, said silicon device allowing at least partial passage of the broadband light radiation signal, a germanium device walled behind and optically aligned with said silicon device that responds to a second spectrum of color frequencies of greater length of wave that the first frequency spectrum, and a twin-peak optical filter in front of said silicon device to pass a first spectrum of defined light frequencies within said first spectrum of color frequencies and a second spectrum of light frequencies defined within said second spectrum of color frequencies, said silicon device producing an output X proportional to the reflected light of the product in the first defined frequency spectrum of light, said germanium device producing an output Y proportional to the reflected light of the product in the second spectrum of defined light frequencies.
6. 6. An optical sorting machine having an optical observation station through which a stream of observed products passes by being classified using a plurality of defined light frequency spectra, comprising illumination means to brightly illuminate the current of products in the optical observation station over a broad band light spectrum; a plurality of photo-optical detectors positioned to receive reflected light from the observed products, the reflectivity varying respectively over the broadband light spectrum depending on the respective color of the observed products, each detector of said plurality of photo-optical detectors including a silicon device that responds to a first spectrum of color frequencies in a broad band light radiation signal, said silicon device allowing at least partial passage of the broad band light radiation signal, a sandwich germanium device behind and aligned optically with said silicon device, which responds to a second spectrum of color frequencies of greater wavelength than the first frequency spectrum, and an optical filter of twin peaks in front of said silicon device to pass a first spectrum of light frequencies defined within said first frequency spectrum of color and a second spectrum of light frequencies defined within said second color frequency spectrum, said silicon device producing an output X that is proportional to the reflected light of the product in the first defined frequency spectrum of light, said device of germanium producing an output Y that is proportional to the reflected light of the product in the second spectrum of defined light frequencies; and a microprocessor connected to said photo-optical detectors to produce an expulsion signal determined by the magnitude of at least one predetermined combination of the outputs X and Y. An optical sorting machine, according to claim 6, wherein said spectra of defined first and second light frequencies are the same for each photo-optical detector. 8. An optical sorting machine, according to claim 6, wherein said spectra of first and second defined light frequencies are not the same for each photo-optic detector.