AU678385B2 - Apparatus for sensing and analyzing surface characteristics of objects - Google Patents

Description

P/00/01Il NJ Regutation IZ

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT

ORIGINAL

TOB OI=BYAPLCN *W e ofApicn

UKITGOERIC

Acua Inetrs: HnyA *ELTadIa HFRM Adrs fo*evc:.LIA A RI,28Hg tet e, 11 itra utai Ineto Tile "'PAAU.O E~N N NLZN UFC CHRCEITC OFOBECS Th folwn.ttmn.safl dsrpino hsivninicuigtebs ehdo pefrmn it knw om: ~arr i I PP 304 APPARATUS FOR SENFING AND ANALYZING SURFACE CHARACTERISTICS OF OBJECTS BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to systems for analyzing surface characteristics of objects by sensing and analyzing surface color reflectivity, and in particular to optical systems for grading fruit according to surface color and surface blemishes.

0* 2. Description of the Prior Art Color and blemish grading systems are in general use within the fresh food industry to grade fruit according to color and blemish categories. One such system is described in Conway, United States Patent Number 5,164,795, entitled Method and Apparatus for Grading Fruit, assigned to the same assignee as the present invention.

For simplicity, the embodiment(s) described in the Specification and Drawing of this copending patent application will be referred to hereinbelow as "Conway" or the "Conway system".

Typical optical grading systems for use on conveyor lines, move the fruit past an array of cameras which scan the fruit to detect surface reflectivities in a plurality of discrete segmental areas on the fruit. Reflectivities of each segmental area (with neighboring areas) are compared, and the spectra are analyzed to determine the degree of blemish and color.distribution for each unit of fruit.

Because these prior art systems are in many ways unduly complex and -le.i1 1 I LI I PP 304 limited in the kinds of blemishes and color variations that can be detected, the assignee of the present invention developed the optical color and blemish grading system described in Conway.

In Conway, two cameras successively scan rotating fruit which is being advanced along the conveyor line to generate surface reflectivity data for each unit of fruit. The fruit is rotated as it is moved down the conveyor line so that, together, the cameras scan the entire surface of the fruit in a single pass under the cameras.

Compensation and adjustment is provided for varying diameter of the fruit during the measurement process.

The fruit is illuminated by an incandescent white light source i.e any filament or arc lamp, producing essentially white light which passes through a heat absorbing glass plate having a polarization coating to prevent glare. The light reflected from the 15 fruit passes upward into the two cameras through a rotating color filter wheel. The filter wheel contains a series of GREEN, RED, GREEN and INFRARED filters for providing color separation of the reflected light. Rotation of the color wheel is synchronized so that a different filter is positioned beneath a photodetector array in each camera for each successive scan of the underlying fruit as the fruit is rotated beneath the cameras.

The data of the image focused by the camera lenses on the photodetector arrays are then stored in a microprocessor which color maps each unit of fruit and makes a decision concerning both color and surface blemish quality. The fruit is then electromechanically sorted according to the color and blemish grading decisions. The color I- ~a lh- e~L- -II PP 304 mapping and decision methodology is conventional and ancillary to the invention, and therefore will not be further described.

Although the Conway system operates well, its operation is subject to certain limitations and frailties. For example, the white incandescent bulbs have an average life rating of 1000 to 2000 hours.

It would be desirable to extend the life of the light source in the system.

Furthermore, as with all electromechanical systems, the filter wheel, filter motor, filters n.d motor capacitor have limited 10 lifetimes, degrade under heat and are subject to wear. For example, although the filter motor may be operating, its operational tolerances must be expected to change with age.

Also, in the Conway system, the incandescent white light sources generate a substantial amount of heat. This heat is eliminated from the monitoring area by using heat absorbing glass over the light sources as well as in front of the filter wheel and cameras.

The associated mounting fixtures and hardware relating to the heat absorbing glass as well as the heat absorbing glass itself represent an additional expense and element which is subject to aging and potential damage.

Additionally, the construction of commercial incandescent bulbs is not very precise. Bulbs exhibit filament sag and nonlinearity. Ceramic electrical connectors are not mounted in-line with the bulb glass, thereby resulting in an offset mounting of the bulb in many cases. Filament sag and non-linearity and inaccurate ceramic connector mounting make it difficult to generate a uniform light

I

I~ICI~ a PP 304 pattern on a surface from the bulb and its associated reflector. And the light pattern will vary with changes in the bulbs, since different bulbs, even of the same brand, will exhibit different construction inaccuracies. This makes it difficult to maintain calibration'in a sorting system.

Furthermore, incandescent systems require a significant amount of energy to operate. And they require extra hardware in the form of power conditioning devices to maintain stability of light radiance with commonly-experienced intensity fluctuations in 0 10 commercially supplied electrical power.

Also, an incandescent source requires high powered .electrical transformers and controls which do not lend themselves to digital logic or software control for real time light intensity changes. Light intensity changes are desirable to control the :15 distribution of light energy in different wavebands of color.

In addition, the incandescent light system requires use of I. a relatively complex and fragile light reflector together with its •associated mounting plate and base plate. It would be an advantage, if possible, to develop a more rugged optical system not requiring such reflectors.

In the incandescent light system, the color filtering is also fixed according to the sequence of colors in the filter wheel.

Although the colors and thei:: sequence could be altered by changing the color wheel, such a change necessarily mandates mechanical disassembly and reassembly of the optical system, and the fabrication of separate color wheels. Again, it would be advantageous to provide ,i III IIP rrsLle PP 304 a system which had flexible and high speed color sequencing according to the specific application at hand.

As is typical of incandescent lighting systems, a .substantial amount of waste heat is generated during illumination. In order to accommodate the amount of waste heat which is generated, cooling fans and systems must be incorporated as well as the use of specialized heat absorbing glass. Nevertheless, the heat remains sufficient in some cases to melt the polarizers which are used in the system and to accelerate the aging of other optical components within the device.

Still further, the Conway system, requires a substantial amount of field time to install, calibrate and service the optical system within the device. It would advantageous to provide a color and blemish grading system in which the optical fixture could be 35 aligned and initially calibrated during factory assembly and thereby minimize the time and expertise required in the field to install and maintain the device.

9* From the above discussion, it can easily be seen that while the Conway system is fully functional, it would be an advantage ."02J0 to provide a color and blemish system having a simpler lighting design with a smaller number of components, in order to maximize accuracy and to minimize time and cost of manufacture and assembly, as well as to reduce its mass, bulkiness and fragility. The provision of a smaller and more rugged optical system would have the benefit of easier transport, installation and calibration.

i ~llsLa a I PP 304 In addition to overcoming the limitations of the prior design, it is still further desirable to provide a system having capabilities which were not achievable or, at best, poorly achievable in'the prior system. Such capabilities include a system which" provides greater measurement uniformity from line to line of the scan by avoiding differences in filter characteristics or aging, or to provide a color and blemish controller as a plug-in module which can be integrated into a central computer for logging. Such a controller module, ideally would also have the ability to be programmed by hand-held computer in case of central computer failure.

*o It would also be desirable to provide a universal color and blemish system for all citrus or other fruits, or other objects, or to provide a color and blemish system which could scan fruits or other objects at variable conveyor speeds. It would be clearly 15 preferable if the color and blemish controller should be easily o replaceable in the field; if it could be easily interchangeable for different graded fruit varieties or other objects with minor optical and electronic modifications; and if it could allow for telephonic programming and debugging of the color and blemish system.

BRIEF SUMMARY OF THE INVENTION An improved optical scanning subsystem is provided for use in a color and blemish grading system which comprises a conveyor system which spins and transports objects (particularly citrus fruit) through the optical scanning subsystem.

I- -I IC bB Il~lslllsraaasla~r II I PP 304 The improved optical scanning subsystem includes one or more cameras for scanning all or a substantial portion of the exterior surface of the objects to be graded. The objects are illuminated by an array of light emitting diodes (LED's). The array of LED's is comprised of a plurality of LED's, of a plurality of different colors.

The colors of the LED's are chosen according to the color and blemish grading procedure which is to be undertaken and the nature of the citrus fruit or other object to be graded. The colors are electronically switched on and off for each set of LED's through digital or other control, and the intensity of individual LED sets can e* 9 •be electronically controlled to optimize the light intensity distribution detected by the sensors. The light reflected from the objects is sensed and may be stored within a computer system and processed to make color and blemish grade determinations based on the relative intensities of the reflected light in selected spectral bands.

The selectively switchable groups of LED's provide a *99999 compact, rugged and less expensive color and blemish grading system than heretofore achieved. In addition, the flexibility of the %.28 switching sequence of the LED arrays allows for a system which may be customized to the type of citrus fruit or other object being scanned.

The system is therefore a universal grading system for citrus fruits, and may readily be adapted for color and blemish grading of a wide variety of other fruits, food products and natural or manufactured objects. The servicing, maintenance, calibration and installation of the system in the field is simplified as a result of the improvement.

-1 IT l II~BI~a PP 304 The invention may be better visualized by :ow referring to the following figures of the Drawing, wherein like elements are referenced by like numerals.

BRIEF DESCRIPTION OF THE DRAWING Figure 1 is a perspective drawing of a conveyor belt in which the invention is incorporated.

Figure 2 is a diagrammatic side view of the optical scanning system of the invention.

Figure 3 is a simplified diagrammatic perspective view of the illumination hood carrying an LED array.

Figure 4 is a diagrammatic depiction of the LED array as it appears in the hood from its inside surface as would be seen if the hood were laid out flatly.

Figure 5 is a simplified schematic diagram of logic circuitry used to control the LED arrays in Figures 2, 3 and 4.

Figure 6a is a simplified schematic of LED drivers used in combination with the logic circuitry of Figure Figure 6b is a simplified schematic of an embodiment of 1280. the reference voltage conditioning circuit of Figure 6a.

Figure 7 is another embodiment showing a generalized computer system in which the invention is embodied.

The invention and its various embodiments may now be better understood by turning to the following detailed description.

rl ~C--Tl_~u Il~aBIL I- -C PP 304 DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The color and blemish grading system of the invention is an improvement over the system described in Conway. However, many parts of the present system are identical to those described in Conway, and their description will not be repeated except to the extent necessary in order to provide a foundation for understanding of the improvements. For the purpose of providing an enabling disclosure as to these elements, Conway is herein expressly incorporated by reference.

".10 In the illustrated embodiment, the system is used in I o"o connection with a conveyor line for grading fruit, and in particular citrus fruit. However, it is to be expressly understood that the method and apparatus of the present invention need not be limited in its application to fruit or, for that matter, to food products, but may be used to color and blemish grade natural and manufactured objects of many kinds.

Figure 1 is a perspective view of a conveyer system t :incorporating the invention. In the illustrated embodiment, fruit 11 is spun and transported in a direction 9 on conveyor 15 through camera a2 assembly 13, wherein the fruit is optically scanned.

In the preferred embodiment, fruit 11 is transported while spinning beneath a first camera 19 and then second camera 17. Two cameras 17 and 19 are used as described in Conway for the purpose of scanning the entire surface of the fruit, since at any one instant, only a portion of the fruit's surface can be reliably scanned. Thus, one portion of the fruit's surface is scanned while being transported I- 1 I LI rsl Prrm PP 304 beneath camera 19, while the remaining portion of the fruit's surface is scanned when it is disposed beneath second camera 17. However, it is expressly contemplated that the methodology and apparatus of the present invention could be utilized with a single camera, together with synchronized movement and spin of the fruit, in a manner consistent with the spirit and teachings in the present application.

Each camera 17 and 19 images the light sensed onto an associated optical sensor 18 and 20, respectively. The optical sensors detect the instantaneous intensity of light imaged onto them.

IIn a conventional manner, each of the optical sensors 18 and outputs an electronic signal whose instantaneous amplitude corresponds to the instantaneous intensity of the light imaged by its associated camera 17 and 19. These signals are analyzed by computer means, not shown, in the manner and for the purposes described inT the 5 aforementioned Conway reference.

Each camera 17 and 19 is provided with an illumination hood 21 and 23, respectively, shown in side elevation view in Figure S" 2. The illumination hoods 21 and 23 may assume any configuration well known in the art, such as parabolic, cylindrical or a compound angular shape, as may be desired. Figures 2 and 3 illustrate the shape of hood 23 as being generally cylindrical.

A plurality of directional light emitting diodes are mounted to the inner surfaces 22 and 24, respectively, of hoods 21 and 23 to form an array of LED's 30, as better depicted in the plan view of Figure 4. A central portion 25 of each of hoods 21 and 23 is cut I a r q II I r I PP 304 out to allow the insertion of the imaging lens of cameras 17 and 19, respectively.

It is to be understood that the illustrations of the hood 23 in Figures 2, 3 and 4 are spatially exaggerated to show detail. In actuality, the LED's 30 within each of the arcs 31, 33, 35 (which extend vertically in Figure 4) are much more numerous and closely spaced within their respective arcs, and the arcs 31, 33, 35 are typically more closely spaced from one another longitudinally in a horizontal direction in Figure 4) along the inner surface 24 of 10 the hood 23.

*ooo As perhaps best shown in Figure 4, the interior pattern of the array, generally denoted by a reference numeral 27, of LED's 30 is illustrated. The interior surface 24 of hood 23 has been spread out essentially flatly to diagrammatically present what would be seen by a 1 unit of fruit 11 passing in the direction of flow 9 underneath hood 23. In the illustrated embodiment, the array 27 is set forth in the shape of a curved rectangular matrix of arcs of LED's each extending (vertically, in Figure 4) within the inner surface 24 of the hood 23, in an essentially transverse direction to the axis of the hood 23 transverse to the direction of flow 9 of the fruit 11.

In the illustrated array, two arcs 31 of LED's 30 comprise LED's of a first color, Cl. A third arc 33 of LED's comprises a plurality of LED's of a second color, C2. Two additional arcs 35 of the array similarly comprise a plurality of LED's 30 of a third color, C3. Any colors may be chosen and arranged in any order or pattern as may be desired.

aarr i, 111-- -B I PP 304 In the preferred embodiment, the LED's 30 in arcs 31 are GREEN LED's having a center wavelength of 565 nanometers and each having a brightness of 180 to 640 mcd at 20 milliamps. Such are manufactured by Toshiba America, of Irvine, California, and available from AND of Burlingame, California, as Part Number AND180PGP. The LED's 30 in arc 33 provide a red color centered at a wavelength of 660 nanometers, each with a brightness of 1800 to 4100 mcd at 20 milliamps and are available from AND as part number AND180CRP. The LED's 30 in arcs 35 are gallium aluminum arsenide infrared LED's having a center wavele:ngth at about 880 nanometers with a rated intensity of greater than 40 milliwatts per steradian at 100 milliamps, and are available from Siemens Components, Inc., of Cupertino, California as Part Number SFH485-3.

o It is entirely within the scope of the invention that other types of light emitting diodes or switchable light sources could be used other than those described, as well as choosing colors and intensities other than those specified.

Figure 4 diagrammatically depicts two arcs 31, one arc 33 and two arcs 35, of LED's 30. The number of arcs and the number of LED's within each are are largely determined by the light intensity level and illumination pattern desired. In another embodiment of the invention, three arcs of each color of LED's may be provided in each hood 21 and 23. The number of arcs and the number of LED's within each arc need not be equal for each of the colors associated with LED arcs 31, 33 and 35. The number and distribution of LED's 30 may be -12s81 I I PP 304 increased according to the degree of illumination which each LED is able to provide.

Still further, LED's 30 of one color need not be segregated into separable sets within the array of LED's. The-LED's of various colors may be intermixed across the entire interior hood surface to provide a uniform illumination for each color.

In addition, focusing optics may be used in combination with individual LED's 30 or with entire hoods 21 and 23, such as a S" cylindrical or prismatic focusing lens 37, as depicted in Figure 3, S..0 which tends to focus all the light received by lens 37 onto a line of focus 39. Also, the LED's 30 of any particular color(s) may be set "into the hoods 21 and 23 at selected angles to facilitate focusing of such color(s) at some specific position(s) along line of focus 39.

One example of the circuitry which can be used to switch the LED's 30 in arcs 31, 33 and 35 is illustrated in the schematic diagrams of Figures 5, 6a and 6b. An indexing signal, INDEX, is received from the conventional drive circuitry for the imaging cameras 17 and 19 so that it is synchronized with or triggers counter 41.

Counter 41 then produces a clock signal, CLK, which is provided to an encoder 43. The encoder 43 then produces a timed sequence of signals, GREEN 1, RED 1, GREEN 2, INFRARED (IR) 1, GREEN 3, RED 2, GREEN 4, INFRARED (IR) 2.

What is described in connection with Figures 5, 6a and 6b is a circuit implementation that simulates the color wheel rotation of the prior system described in Conway. For example, in the Conway system, eight color filters are provided in the wheel, so that two

I

ill

I

PP 304 sequences of color filters are passed before the cameras in one rotation of the wheel. Therefore, the signal, INDEX, corresponds to the time interval of one rotation of the filter wheel in the Conway system. The filters are arranged in the preferred embodiment -of the color wheel of the Conway system in the order of GREEN (or cyan), RED, GREEN, INFRARED and then repeated with the same four colors in the same sequence.

Processing of the data in the Conway system is then based upon this assumed format, although many other formats could have been '1 .0 devised. GREEN is a repeated color, because in the case of citrus fruits, GREEN is the color most principally related to the surface I quality of the fruit. It is entirely within the scope of the invention that other color sequences and formats could be chosen according to the expected color characteristics of the object being scanned.

The signals GREEN 1 and GREEN 2 are then combined in OR gate 45, while signals GREEN 3 and 4 combined in OR gate 47.

Similarly, the infrared signals, INFRARED (IR) 1 and INFRARED (IR) 2, .are combined in OR gate 49, while the signals RED 1 and RED 2 are combined in OR gate 51. The outputs of OR gate 45, corresponding to the GREEN 1, 2 signal, are then coupled with the output of OR gate 51, corresponding to the RED signal, to a clocked flip-flop 53. The output of the flip-flop 53 is the signal, GREEN 1, 2 DELAYED, and RED DELAYED, which is synchronized to the clock signal and which are mutually exclusive. there is either a GREEN 1, 2 DELAY or RED DELAY signal, but not both.

-14i I I il I IIIL~- II PP 304 Similarly, the output of OR gate 47, corresponding to the signals GREEN 3, 4, is coupled with the output of OR gate 49, corresponding to the signal INFRARED and directed to the clocked flip-flop 55 to produce the timed signals INFRARED (IR) DELAYED and GREEN 3, 4 DELAYED. The GREEN 1, 2 DELAYED and the GREEN 3, 4 DELAYED signals are combined, and then each of the delayed signals are coupled through an invertor to a circuit driver, as shown in the schematic of Figure 6a.

.,Considering first the signal corresponding to the inverted 0 GREEN DELAY signal, a reference voltage Vref is provided by the .c reference voltage conditioning circuit 58, as show schematically in Figure 6b, at node 57 to which is coupled a calibration potentiometer 59. The input to a Darlington pair 61 is thereby biased by the output of a differential amplifier 63 which has, as one of its inputs-, the 15 calibration voltage from potentiometer 59. The other input to differential amplifier 63 is a feedback signal, G, derived from the switching transistor 65 coupled to the LED serial chain 31. The input to the Darlington pair 61 is the inverted GREEN DELAY signal.

*Therefore, the Darlington pair 61 will be turned on, thereby driving the switching transistor 65 and then turning on the GREEN LED's 31 until such time as encoder 43 presents a valid RED signal to the input of clocked flip-flop 53. At this time, the inverted RED signal is active, driving RED LED's 33. Red LED's 33 then remain on until the RED signal goes inactive and the signal GREEN 2 from encoder 43 goes active, ultimately turning on GREEN LED's 31 again. GREEN LED's 31 then remain on as long as GREEN 2 is active, until encoder 43 causes I R IIIYII~C~a PP 304 INFRARED (IR) 1 to go active, causing GREEN LED's 31 to be extinguished and INFRARED LED's 35 to be ignited by the inverted INFRARED (IR) DELAY signal drive from clock flip-flop The reference voltage at node 62 may be selectively adjusted by means of a conventional voltage control circuit (not shown). Such adjustment of the voltage at node 62, in conjunction with adjustment of the clock cycle of flip-flop 53 or 55, can be utilized to vary the current and on-time of LED banks 31, 33, :This provides a means to selectively and independently control the intensity and duration of LED light emissions of selected wavelengths and selected combinations of wavelengths.

It is well known that LED's of a given wavelength may exhibit a standard energy emission which varies from that of LED's of other wavelengths. Thus it is desirable to be able to control the duration and emission intensity of each LED bank 31, 33, 35 in order to optimize the signals at the sensors 20. In a conventional manner, the node 62 voltages and flip-flop 53, 55 clock cycles can be independently hardwired or controlled in-process from a CPU 67 or from digital logic.

Half the cycle is thus completed, corresponding to half a rotation of the filter wheel in the prior system, and the sequence is again repeated, after which the signal, INDEX, then resets counter 41 and the cycle begins anew. It is to be expressly understood, however, that the driving signals to the LED driver, as shown in Figure 6a, may be entirely derived from software control, as opposed to the hardware -16- I -I BWC-- I PP 304 implementation depicted in Figure 5. Therefore, it is entirely within the contemplation of the present invention that a software driven central processing unit may generate the triggering signals to LED arcs 31, 33 and 35 in other sequences and in other orders. Fo example, it is expressly contemplated that in addition to exclusively turning on one color of LED's 30, that multiple colors of LED's may be turned on and off at the same time. Data processing of the reflected light would thereafter proceed by a color integration or subtraction process, such as would be the case, for example, if the color cycle were, instead, GREEN and RED, GREEN, GREEN and INFRARED, and then GREEN. It is expressly contemplated that longer exposure times to favored colors, as is in the case of green with citrus fruit processing, may have advantages when data reductions are made.

Again, it is also expressly contemplated that the method 5 and apparatus of the invention need not be limited to three colors, but that four, five, six or more sets of differently colored LED's could be used to obtain finer color and blemish grading than was heretofore achievable. Additionally, having a wider color capacity gives the system the capability of color and blemish grading types of fruit other than citrus fruit, thereby yielding a more universal grading system, one that can be adapted from one type of food product to another by simple software selections.

One such system in which this may be implemented is shown ir the block diagram of Figure 7. A conventional CPU 67 is coupled to a control and data bus 69 along with memory 71. LED drivers 73, similar to those shown in Figure 6a, are coupled to bus 69 for driving IrI PP-- IA~ PP 304 a plurality of LED banks 75(1), 75(N). The architecture of the system allows it to be reprogrammed, calibrated and tested by a plug-in portable field programming circuit 77 diagrammatically depicted in Figure 7. In other words, the portable field programmer may include a hand-held portable microprocessor and memory with a digital keypad and LCD/LED display, which allows the operator in the field not only to test the system, but to load new programs into memory 71 for execution by CPU 67, as may become available from time to time, or as may be necessary to grade different types of food o 40 products, or other natural or manufactured objects.

In addition, the computer system of Figure 7 may include a conventional modem 79 coupled through telephone line 81 to a remote central processor (not shown) for the purpose of not only logging the grading and sorting operation conducted by the system, but also to allow programming and debugging by off-site skilled personnel, thus eliminating the need for many field trips for service and maintenance, as may be required by the Conway system.

Therefore, it may readily be appreciated that what is provided by the improvements of the present invention is an illumination source comprised of LED's, which have a life of typically 30,000 hours, which life is more than an order of magnitude longer than the incandescent illuminating system described in Conway. The expense and problems related to electromechanical filter wheels and heat damage caused tc such components by the incandescent lighting system are also eliminated. The need for complex and fragile heat absorbing glass plates, and associated mounting fixtures and hardware, -18- II ~I~YIPC1' PP 304 together with the need for complex and fragile light reflectors together with its associated mounting hardware, have also been eliminated. The size and mass of the system have been reduced, and its ruggedness has been substantially improved, as have problems associated with non-uniform commercial filaments and ceramic connector mounts. Problems previously related to damage or misalignment of the optical system during transport, installation and calibration have also been eliminated. The calibration procedure has been simplified and can be performed in the field by unskilled operators or, if 0 necessary, remotely monitored.

In addition, operational features not heretofore realizable have been achieved. The uniformity of scan from line-to-line has been increased because of a uniform illumination level on each scan. The flexibility of color sequencing has been dramatically improved and can be reliably implemented in the field by unskilled personnel through portable field programming circuits, or o. remotely through modem communications. The result is that a universal color and blemish grading system for all types of citrus fruits or other food products and manufactured objects is now realized. Because sequencing of the LED's is arbitrarily controlled through computer logic or software, conveyor speed can be selectively varied according to the processing needs.

The illustrated embodiment has been set forth only for the purpose of example and should not be taker, as limiting the invention as defined in the following claims.

-19- Ir

Claims (24)

1. The apparatus for sensing and analyzing the reflectivity of at least a portion of the surface of an object, comprising: a light source whose output is directed toward that portion of the surface of the object, said light source comprising an array containing a plurality of switchable light emitting diodes, each of said switchable light emitting diodes emitting light within an individual selected waveband, said array collectively generating light containing a plurality of individual wavebands; sensing means to sense the light reflected from that portion of the surface of the object; and ego• ;analysis means receiving the input from said sensing means, to o analyze the reflected light.

2. The apparatus as recited in Claim 1, further including means to rotate the object while its surface is illuminated by said light source. i 1

3. The apparatus as recited in Claim 1, further including means to linearly move the object in a selected direction while its surface is illuminated by S said light source.

4. The apparatus as recited in Claim 1 wherein said sensing means senses the reflected light at a sequence of different times, and said analysis means is adapted to compare the reflected light sensed at such different times.

The apparatus as recited in Claim 1, further including switching means to selectively activate said switchable light emitting diodes. 21/3/971S7337.CLM,20 I I IC -21-

6. The apparatus as recited in Claim 5, wherein said switching means is adapted to cause said light source to selectively generate light of only one of the individual wavebands at a selected time.

7. The apparatus as recited in Claim 6, further including control means to control the intensity of the light generated in said one of the individual wavebands.

8. The apparatus as recited in Claim 6, further including timing means to control the on-time of the light generated in said one of the individual wavebands.

9. The apparatus as recited in Claim 6, wherein said switching means is o S adapted to cause said light source to selectively sequentially generate light in each of the individual wavebands of the switchable light emitting diodes comprising said light source.

10. The apparatus as recited in Claim 1 wherein a plurality of light o 1 6: sources and a plura!ity of light sensing means are provided, each of said sensing means adapted to sense the light reflected from the surface of the object at a different time, and said analysis means adapted to receive the input from each of said sensing means.

11. The apparatus as recited in Claim 1, wherein at least three individual wavebands of light are a generated by said light source.

12. The apparatus as recited in Claim 1, wherein each of said individual wavebands consists essentially of monochromatic light. 2113197JS7331.CLM,21 I L L 1~ 22

13. The apparatus as recited in Claim 12 wherein said individual wavebands comprise green, red and infrared.

14. The apparatus as recited in Claim 11, wherein four or more individual wavebands of light are generated by said light source.

15. The apparatus as recited in Claim 2, wherein said analysis means is adapted to determine the extent of blemishes on the surface of the object.

16. The apparatus as recited in Claim 1, wherein said analysis means is adapted to determine the approximate colour of that portion of the surface of S the object.

17. The apparatus as recited in Claim 1, further comprising means to focus the output from said light source onto the object.

18. The apparatus as recited in Claim 1, further comprising computer means to selectively activate said switchable light emitting diodes.

19. The apparatus as recited in Claim 18, wherein said computer means S19 comprises an electronic circuit designed to implement such selective activation. 466

20. The apparatus as recited in Claim 18, wherein said computer means is software controlled.

21. The apparatus as recited in Claim 18, wherein said computer means is adapted to be programmed from a remote location by means of a modem.

22. The apparatus as recited in Claim 1, wherein each of said switchable e!ectronic light emitting diodes inherently emits light within a single, narrow, fixed waveband, and wherein said array collectively generates light containing a plurality of individual fixed wavebands. 2113197IS7337.CLM,22 I I, ILI I- -23-

23. The apparatus as recited in Claim 22, wherein each of said switchable light emitting diodes generates light of substantially fixed amplitude.

24. An apparatus for sensing and analyzing the reflectivity of at least a portion of the surface of an object substantially as hereinbefore described with reference to the accompanying drawings. DATED this 24th day of March, 1997 SUNKIST GROWERS, INC. By their Patent Attorneys: CALLINAN LAWRIE S* .4 I* 'a f* a aa oo*4 ftfot o•f f ft o 21/3/97JS7337.CLM,23 S6~P lsll 11 Ips~slsrs~ PP 304 APPARATUS FOR SENSING AND ANALYZING SURFACE CHARACTERISTICS OF OBJECTS ABSTRACT OF THE DISCLOSURE A versatile color and blemish grading system for various objects, including citrus fruits, is improved by the use of light emitting diodes of selected colors as the source of illumination. The object to be graded is conveyed beneath a camera and illuminated by selectively switched banks of monochromatic light emitting diodes. The sequencing and switching of multiple colors of light emitting *,99 diode banks is controlled by lgic design or software. The versatility as to sequencing, the number of scanning colors which may be used, calibration, maintenance and programmability are dramatically improved over prior systems using incandescent white light sources and color wheel filters. 99* 'P r'