DE2218134A1 - Method for displaying the amount of light reflected by an illuminated object and the arrangement for carrying out the same - Google Patents

Description

Patent attorneys Dipl.-Ing. F. Weickmann, 2218134

Dipl.-Ing. H.Weickmann, Dipl.-Phys. Dr. K. Fincke Dipl.-Ing. F. A. Weickmann, Dipl.-Chem. B. Huber

DXIII 8 MUNICH 86, DEN

PO Box 860 820

MÖHLSTRASSE 22, NUMBER 48 39 21/22

<983921/22; ·

Mandrel Industries Inc., 0909 Southwest Freeway, ilouston,

Texas, USA

Method for displaying the amount of light reflected by an illuminated object and arrangement for implementation

same

The present invention relates to a method for displaying the amount of light emitted by one in the optical frequency spectrum illuminated object is reflected, as well as a color monitor arrangement for performing this method.

The method according to the invention and the arrangement according to the invention are particularly suitable for displaying a deviation in the color or in the hue of a product in the optical frequency spectrum, whereby an output signal is generated, which is a measure of the deviation of the color from a preselected

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th color is independent of changes in light brightness in the surroundings.

For industrial purposes, there is an increasing need for control options for the color of a product, during its processing. This color control can, for example, for reasons of color matching or monitoring of the The processing state of a product may be desirable, for example when dyeing, roasting, baking, mixing, sorting, etc., is the case. Furthermore, it can also simply be a question of between different items of products to maintain a constant color, which is characteristic of the product and / or which is a for the consumer pleasant appearance of the product guaranteed.

For example, merchandise such as peanuts, coffee beans, potato chips, baked goods, etc. must be up to roasted, baked or mixed to a certain extent, these processes generally resulting in a certain color and are thus identified by this color. This can be, for example, a brown shade, a stain shade, act a yellow-brown tone, a red tone, etc. In these cases, the hue is a measure of the degree of processing of the product. This degree of processing of the product not only directly determines the taste and thus the quality of the product, but also its appearance and thus its visible quality for the consumer.

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Furthermore, agricultural products such as unripe, ripe or overripe tomatoes require freshly peeled Peaches and pears have to be separated before further processing in order to protect them from various external influences, such as temperature, storage, over time, etc., to various degrees to be able to suspend, so that an equally good end product is guaranteed. In this case the color is a hatred for the degree of maturity of the product.

Furthermore, in the production of paints, textiles, paper, tiles, etc., it is desirable to ensure a constant color in order to avoid deviations which are unpleasant to the eye to keep the shade as low as possible.

Known possibilities for ensuring color matching are to take a sample of the product after it has been processed or during its processing and thereby a color comparison with a processed product and a color standard by means of a spectrophotometer, a colorimeter or another corresponding arrangement. Such a procedure is unwieldy, time consuming, and can generally not be carried out continuously during the actual processing of the product. Much more Such a method can only be carried out after processing or partial processing. From this it follows that the processing device cannot be corrected during the processing process in order to compensate for color deviations of the product from the required color

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to be able to. In known arrangements of this type, it is also not possible to continuously generate signals which are a measure of the color of the product and can be continuously traced back to the processing device, in order to immediately compensate for color differences during the processing of the product.

The present invention is based on the object of specifying a method and an arrangement of the type in question, in which the disadvantages of those explained above known methods and arrangements are avoided. This task is performed in a method of the type mentioned at the beginning solved according to the invention in that the ratio of two specific, reflected from the same area of the product Wavelengths are measured, which is a measure of the color of the product.

In a further development of the invention, a color monitor arrangement for carrying out the aforementioned method for continuously displaying the amount of light which is reflected by a product illuminated in the optical frequency spectrum is implemented the following features:

an electro-optic system for observing the same area of the product in a pair of coaxial optics Because of two spectral wavelengths in the optical frequency spectrum, the optical paths being light values of reflected energy at the two wavelengths, which are a measure of the color at these wavelengths,

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and an electrical arrangement coupled to the electro-optical system for generating a ratio of the I_. devalue, the wet for the reflected energies in the Wavelengths and thus the color of the product.

The present invention thus provides a method and an arrangement in which an electro-optical system can be operated continuously and automatically in order to monitor color during an entire machining process Product and not just with a selected product. The system is basically exposed an electro-optical observation arrangement and an electronic computer control arrangement together. Since the Observation of the color of an area depends on the intensity of the different reflected colors, represents the calculation of the ratio of the intensities between two special colors, which in adaptation to the special product are selected, a means for displaying the color of the product. Any change in intensity of either of the two selected Irrespective of how small they are, colors lead to a change in the color ratio determined according to the invention, as a result of which an output signal can be generated which is a measure for is the change in the ratio and thus for the difference or the deviation of the color shade of the product from the desired color.

According to the invention, a combination of an optical arrangement for illumination and for the coaxial observation of the

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illuminated product provided. The coaxial optical observation arrangement is connected to electro-optical converters coupled to a pair of electrical output signals generate, which are a measure of the intensities of the two preselected colors, with the electrical output signals are synchronized in time. These synchronization output signals are in turn fed into a computer control arrangement. Any deviation in the ratio of the color intensities represented by the electrical output signals leads to a change in the output signal of the computer control arrangement, this change being displayed and / or as a feedback signal can be used to control the processing device that brings about the change in the color of the product.

The system is calibrated by providing an optical reference structure of predetermined reflectivity corresponding to the reflectivity of the product in the observed area and adjusting the calibration of the computer control system to provide an output signal corresponding to the reflectivity of the predetermined optical reference structure. After this calibration, the light reflected and displayed by the products, materials, etc. has a special bichromatic color value which corresponds to the product color, resulting in an output signal corresponding to the product color. The color monitor arrangement according to the invention can also be used in many of the sorting devices available today in which a chrominance selection process is carried out.

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It is particularly suitable for cases in which between a large number of gradually changing color tones must be distinguished. The arrangement according to the invention can instead of optical observation arrangements and electronic color detection arrangements, which are generally present in such known sorting devices, are used. Color changes in such known sorting devices can be achieved by means of the arrangement according to the invention can be displayed as a change in color ratio, an output signal being generated which is a measure of a change in color is. An arrangement according to the invention can be used per channel of the sorting device, so that successive values of the electrical output signal can be assigned to successive separate sorting channels, with the product is separated according to the successive colors or hues as it passes through the optical observation arrangement.

Further features and details of the invention emerge from the following B < of the figures. It shows:

from the following description of embodiments based on

Fig. 1 is a simplified block diagram of the basic electro-optical system according to the invention;

FIG. 2 shows a more detailed block diagram of the system according to FIG. 1 with a modified optical system according to FIG the invention;

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Figure 3 is a simplified elevational view of an optical

System forming an optical synchronization system according to the invention;

Fig. 4 is a simplified cross-section taken along line 4-4 in Fig. 3;

FIG. 5 shows a simplified elevation view of the optical viewing system which, together with the optical system according to FIGS. 3 and 4, together forms observation and synchronization optics according to the invention; FIG.

6 is a detailed circuit diagram of an embodiment of FIG

electronic computer control arrangement according to the invention;

7 shows an illustration of the layout of the front side of the computer control arrangement according to the invention, which includes the various controllers shown schematically in FIG shows in detail; and

8 shows a diagram of the functional relationship between the wavelength and the reflectivity.

In Fig. 1, a color monitor arrangement 12 is shown schematically according to the invention. A conveyor device is placed in it for the products, such as a chute or an endless conveyor belt 14 illuminated by a light source 16, which for example an incandescent lamp, a fluorescent lamp

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and can be a combination of both. Products 18 are shielded by a shield 20 from light from the environment which causes color changes. The screen 20 is not required for changes in light brightness, since the arrangement according to the invention carries out a division process in which both input variables are subjected to the same changes in brightness, so that they are extinguished by this division process. An electro-optical observation arrangement, generally designated 22, contains a synchronization lens system 24 which is arranged coaxially at a distance from an object link system 26. The lens systems 24 and 26 are shown, for example, as plan-convex double lenses. Optical diaphragms 28 and 30 are arranged in the lens systems 24 and 26. The lens systems 24 and 26 together with the diaphragms 28 and 30 form a common coaxial optical system in the form of an optical object system and an optical synchronization system, which are arranged coaxially to one another. This common coaxial optical system forms an optical path 38, which can be referred to herein as "observation ^{beam 11.} This" beam "38 is formed by the light reflected from the product and shaped and guided by the optical part of the electro-optical observation arrangement 22 An optical slide 29 is arranged in the objective lens system 26, by means of which all the light radiated onto the observation arrangement 22 can be blocked during the calibration process.

Through the objective lens system 26, that originates from the product 18 Light collected and focused in an image plane A, which

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surface in the synchronization lens system 24 (planoconvex double lenses) is located. This plane represents a focal point for the image of the product 18. The optical shutter 28 is arranged in the image plane A, whereby the image of the object 18 is limited. This BJe nde 28 is made of opaque Material made and has a central opening 31, the size and shape of which is determined by the area of the product 18 to be observed. The aperture 28 continues to limit the field of view to avoid unwanted light from outside the to eliminate the desired observation area.

A synchronizing optical diaphragm 30 is arranged in the object lens system 26 (plano-convex double lenses). Dti behind that synchronizing lens system 24 and the optical diaphragm an uncolored, semitransparent play beam splitter 36 is arranged. This splitter 36 guides part of the light from the limited image plane A onto a photo-electric sensor 32, and erects the remaining part of the light a photo-electric sensor 34. The area formed by the synchronizing shutter 30 is determined by the synchronizing Lens system focused in image planes B and C, which in photosensitive elements 33 and 35 in the photo-electric Sensors 32 and 34. The synchronizing diaphragm 30 is made of light-impermeable material and has a central opening 40, the size and shape of which is determined by the shape of the photosensitive areas of the phuto-sensitive Elements 33 and 35 are defined. In the way of the photo-electric sensors 32 and 34 reflecting rays

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color filters 42 and 44 are arranged.

Since the object for the synchronizing system is determined by the area formed by the synchronizing diaphragm 30 becomes, the light received by the photo-electric sensors 32 and 34 is in synchronism. That light is complete diffuse, so that no image characteristics of the product IG or the diaphragm 28 result. According to the invention the color of the product by calculating the ratio of two specific wavelengths of the reflected light displayed, these two specific wavelengths depending on the color of the product. This light goes from exactly the same area of the product. Each color tone is characterized by its own identification-difference ratio represents.

The characteristics, ie the color wavelengths, of the filters 42 and 44 are determined by the product to be sorted. It is assumed, for example, that the product is potato chips which are baked in hot oil in a device (not shown) and brought onto the conveyor belt 14. In this case, the filters 42 and 44 are chosen so that they pass special narrow bands (ie wavelengths) of bluish green and red light (496 and 676 nanometers), as the ratio of the bluish green and red light emitted by one Potato chip is reflected as the baking time increases; that is, the bluish-green light decreases faster than the red light beam when the chips change color

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changes from a white cream color to a strong rust color during treatment in hot oil. The progression of the The baking process and thus the appearance of the potato chips is thus indicated by the change in the ratio of regulates bluish-green to red light.

The diagram according to FIG. 8 shows the process of changing the color of the potato chips during the baking process relative to the ratio values generated by the arrangement according to the invention. This diagram is understandable per se without further explanation. At the wavelength of the ζ-channel filter 42 (for 496 nanometers) a "bright" chip (a chip that has not yet been baked through) reflects 47> S of the light, while at the wavelength of the y-channel filter 44 (676 nanometers) it reflects 74 % of the light reflected. On the other hand, a "dark" chip (an over-baked chip) reflects 40 % of the light at the wavelength of the Z-channel filter 42 and 70 % of the light at the wavelength of the y-channel filter 44. Therefore, the filter 42 sees a decrease of 7 % of light reflectance, while filter 44 sees only a 7% decrease in reflectance. If a ratio z / xy is measured while the chip is being baked, this is 47/74 or 63.5 % for a chip that has not been baked sufficiently and 40/70 or 57.1 % for a chip that has been baked too much Difference in these ratios of 63.5 - 57.1 = 6.4 %. This ratio can be determined by the extremely sensitive arrangement according to the invention, since it is set in such a way that there is a full scale deflection for a difference of 10 % of the ratios. In this way there can also be deviations

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in the order of 0.1 % can be easily detected and displayed by the arrangement according to the invention.

The electrical output signals of the photo-electrical sensors 32 and 34 (hereinafter referred to as color signals) are proportional to the intensity of the two color values which are from filters 42 and 44 are supplied. These color signals are transmitted via a voltage-controlled line driver 47 low output impedance (Fig. 2) and a cable 43 of predetermined length to an electron computer control arrangement, generally designated 46 given. The line driver 47, to be described in more detail below, contains a according to FIG Pair of 100 / Sig feedback operational amplifiers ^) and with field effect transistors in the input circuits (for example, type Faiachild 740), which are independent of changes in the Length of the cable 48 represent a very small output impedance for the computer control arrangement 46. The voltage controlled Operational amplifiers 50 and 52 are thermally coupled by a metallic ring 53 (shown as dashed lines), whereby the drift due to temperature differences between the amplifiers is compensated.

The color signals from the electro-optical converters 32 and 34 are applied to an analog multiplier-divider 54, which will be described in more detail below in connection with FIG. The divider 54 represents an arrangement which is a true forms an analog ratio, i.e. its output signal is a true ratio or a division of the given to it Color signals. A typical divider 54 can be the Model 107C from Hybrid Systems Corp. Find use.

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Since the two color signals given to the divider 54 are a measure of the intensities of the colors produced by the product and given via the filters 42 and 44, the result is that the output signal of the divider 54 (hereinafter referred to as the color ratio signal) is true Corresponds to the ratio of the two colors. This color ratio signal is given to a signal display instrument 56 and to an output 58. This signal can be in various formats, which will be explained in more detail below.

FIG. 2 shows in detail an embodiment of the color monitor arrangement 12 according to FIG. 1, components that correspond to one another in FIG. 2 being provided with the same reference numerals. The product k 18 on the conveyor belt 14 is observed via the optical path 38 which is formed by the common coaxial optical system. A beam splitter 36, which corresponds to the beam splitter of FIG. 1, divides the optical path 38 so that a first pair of reflected and further transmitted light paths is formed. The transmission light path can be observed at a point 60 via an observation arrangement 62 , the actual area on the conveyor belt 14 being observed via the optical path 38, whereby the orientation of the electro-optical observation arrangement 42 relative to the product Io is facilitated. A second beam splitter 54 is arranged in the reflected optical path, with part of the light energy from product 18 being reflected onto a photomultiplier tube 66 of photoelectric sensor 32 via the color filter 32 and the remaining part via the color filter

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onto a photomultiplier tube 68 of the photo-electric FUhlers 34 is transmitted. The arrangement of Fig. 1 is a simplified embodiment of the arrangement according to FIG. 2, in which case it is possible in the latter arrangement that Observe the image in the optical path 38 from the outside.

The electro-optical viewing assembly 22 is arranged according to Figure 2 in a housing 70, also the driver is in the 47, wherein the output signals of the photomultiplier tubes 66 and 68 via load resistors 67 and 69 receives. The driver 47 contains the aforementioned operational amplifiers 50 and 52, which have a very small output impedance. The color signals from the operational amplifiers 50 and 52 are fed into the computer control arrangement 46 (located in a housing 71) as z and y input signals. The variable cable length is determined by the distance between the computer control system 46 (housing 71) and the electro-optical observation arrangement 22 (housing 70). The color ratio signal on an output line 76 is therefore equal to the ratio z / y. Any deviation from one of the colors occurs on line 76 as a change in the preset ratio z / y. On the other hand, any change in the brightness values occurs in both the z and y color signals, so that these brightness changes are compensated for in the ratio z / y.

It is necessary that the filter (42) corresponding to the smaller of the two color values is arranged in the z-channel, and that the filter (44) corresponding to the larger color value is arranged in the y-channel, from which the correct numerical

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ratio for the division process, which is carried out by the divider 54 results. In other words, the smaller value is divided by the larger value, resulting in a percentage less than 100 % , which corresponds to the ratio of the two colors.

The line 76 going out from the divider 54 is coupled to a speed control circuit 78 which contains a member with a variable time constant, which in the present exemplary embodiment is formed by a variable resistor 80 and a capacitance 82 in series with it, which in turn is connected to earth. The slide of the resistor 80 is coupled to an operational amplifier 84 with a field effect transistor in the input circuit, which prevents errors in the electrical signal in that the resistor 80 is loaded. The output of operational amplifier 84 is applied to a pair of terminals 88 to ground 86, resulting in an analog output signal.

In certain applications it is desirable to average out changes in the color of the product. The aforementioned speed control circuit 78 therefore acts as an arrangement for Averaging of the shifts in the color ratio signal. In this way it is possible that a certain time elapses before feedback signals from the control signal system influence the controlled processing device.

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The output signal of the operational amplifier 84 is also given via an analog / digital converter 92 to a plurality of output terminals 90, via which the digital output signals are available via which the color monitor arrangement 12 with digitally designed process control arrangements, such as digital computers, digital recording devices, etc. (not shown) can be coupled which process operations control.

The output signal of the operational amplifier 84 is still given to the display instrument 56, which has a scale 94 for visual display of the output signal as well as high / low set point relay 96 for regulating the operation of the machining device (not shown) via several feedback output terminals 98. The feedback output terminals 98 are Connected via a feedback circuit (not shown) to control devices of the processing arrangement. Here can it is, for example, temperature control of an oven, a baking system or the control of valves in one Act product mixing device / the output terminals 88, 90 and 98 mentioned correspond to the output terminal 58 according to Fig.l.

In the context of the invention it is desirable that the signals which are given by the photomultiplier tubes 66 and 68 to the divider 54 are in phase, that is to say in other words that they are in synchronism in time. The sensitivity of a photocathode surface (denoted here by 33 or 35), however, changes as a function of the position of the light spot impinging on this surface. Therefore

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For example, the output signals-e of the photomultiplier tubes 66 and 68 are not necessarily in phase when a beam of light strikes them, as evidenced by the fact that the photocathode elements are not spatially or photo-optically designed to have linear sensitivity along their surface dimensions results. If the respective outputs from photomultiplier tubes 66 and 68 are out of phase, the division process performed by divider 54 contains an error. This in turn leads to an error in the color ratio signal.

In order to correct this error and to simultaneously observe the same area in the two color channels, the "optical synchronization system", which is formed by the synchronizing optical diaphragm 30 and the synchronizing lens system 24, is provided according to the invention. The size of the opening 40 in the optical diaphragm 30 is chosen so that it is adapted to the dimensions of the "area of best light collection" of the photocathode elements 33 and 35. Furthermore, according to the invention, the common optical observation arrangement is provided in combination with the optical synchrinsation system in that the optical diaphragm 28 and the objective lens system 26 are arranged coaxially. These combined optics form a common coaxial optical observation path 28 in conjunction with the optical synchronization system.

In FIGS. 3 and 4, the synchronization optical system is devoid of the objective lens system 26 and the optical diaphragm 28 shown, i.e. these figures show the optics without the

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observing part. As noted above, the photomultiplier tubes do not always provide in-phase outputs when the entire surface of their photocathode elements is struck by light. According to the invention, the opening 40 in the optical diaphragm 30 is therefore selected so that it is slightly smaller than the "area of best light collection ^11. Since the two light beams given to the photo-electric sensors 32 and 34 emanate from the same area at the same time and because they are on The "areas of the existing light collection ^{11 of} the tubes 66 and 68 are irradiated, these agitators 66 and 68 provide synchronous signals, whereby it is ensured that the signals given over the lines 73 and 74 to the divider 54 are in phase. This enables an exact division of the two color signals.

Fig. 5 shows that part of the optical system which defines the optical observation path 38 and which together with the optical Synchronisaiionssystem according to FIGS. 3 and 4 forms the common optics for observing the product, with synchronous electrical signals are generated, which are a measure of the color of the product. The light from Product 18, that through the objective lens system 26 is collected is focused on an image plane A of the synchro-lens system 24. Of the The observation area on the conveyor belt 14 is defined by the optical diaphragm 28, which is arranged between the two plano-convex lenses of the lens system 24, this area being, for example, circular, rectangular or can be square.

Optical lengths L2, L3 and L4 (and

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thus the focal length of the synchronizing lens system 24) is determined by the dimensions, spacing, etc. of the photocathodes in relation to the image formed by the optical apertures 30. The focal length of the objective lens system 26 is determined from the sizes L ₁ and L «. As mentioned above, the size of the optical shutter 30 is determined by the size of the photocathode elements 33 and 35. The optical length LI is determined in connection with the special application of the arrangement 12, be si pielweise by the distance between the electro-optical observation arrangement 22 and the area to be observed. The size and shape of the optical diaphragm 28 is determined by the specific application for the arrangement. This can be, for example, parameters such as the area to be observed, the type of product to be processed, processing conditions, etc.

Fig. 6 shows in detail a circuit diagram of the electronic part of the electro-optical observation arrangement 22, as well as the electronic computer control arrangement 46. Components which correspond to the components according to FIGS. 1 and 2 are denoted by the same reference numerals.

The light in the optical path 38 (FIGS. 1-5) impinges on the photo-electric cathodes 33 and 35 and generates the color signals via the corresponding photomultiplier tubes 66 and 68. The output signals are sent to the load resistors 67 and 69 as well as to the inputs of the operational amplifiers 50 and 52 with field effect transistors in the input

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given circle. The load resistors 67 and 69 are selected as a function of the optical signal value of the product to be monitored. The photovoltaic fans 66 and 68 as well as the color filters 42 and 44 according to FIGS. 1 to 5 are selected as a function of the parts of the optical spectra which are suitable for the product to be monitored.

The cathodes of a pair of clamp diodes 104 and 106 are coupled to the outputs of the photomultiplier tubes 66 and 68. The anodes of these diodes are connected together at a junction of a pair of resistors 108 and 110 which are connected between a negative voltage of -15 V and ground. The diodes 104 and 106 therefore exert a clamping effect, as a result of which the input signal for the driver 47 is limited to 10.1 V in order to avoid overdriving this driver. The free ends of the load resistors 67 and 69 are connected to ground via shunt capacitances 112 and 114, these capacitances preventing the scattering of material. Furthermore, the load resistors 67 and 69 are connected to variable bias networks 116 and 117. The gains of the photomultiplier 66 and 68 are set via gain control networks 118 and 119. In the course of the lines 72 and 74, an operating setting switch 120 is provided which, together with a gain setting circuit 112 and a balancing control circuit 124, forms a circuit for setting the driver 54.

The output of the divider 54 is via the speed control circuit 78 and the operational amplifier 84 with a

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Field effect transistor in the input circuit is given to an analog switch 126 which is connected to the output terminals 88. Furthermore, this signal is given to a digital switch 128, which via the analog-digital converter 92 to the digital Output terminals 90 is coupled. The analog-to-digital converter 92 is of conventional design with common ones Power input, the analog signal being fed in via a trimming resistor 130.

The signal at the output 76 of the operational amplifier 84 is also given to the signal display instrument 56 via a scale modification circuit 132. The circuit 132 contains a combination of a function switch 134, which is coupled to the measuring arrangement 94, an already adjustable switch 136 and a percentage shift switch 138. The function switch 134 allows the selection of the switching contacts and the circuits so that a pickup I the circuit during the calibration process is possible before the monitor arrangement is put into operation. The choice of the switch position of Bereicheinstellschalters 136 makes a change in the Skalenempfindlichkekit Heßanordnung 94 possible while the switch position of the percentage shift switch 138 makes a shift in the percentage adjustment on the scale possible. The switches 136 and 138 therefore make it possible for the instrument to have a greater sensitivity in a predetermined range of scale divisions, as a result of which even small deviations in the color ratio signal can still be easily detected.

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The relay arrangement 96 contains two relays and two sets of contacts, namely a high point relay 140 and a low point relay 142. The contact positions of these relays 140 and 142 are made by mechanical adjustment of appropriate. Upper and lower position marks 144 and 146 on the instrument 94 established. The contact positions of the relays 140 and 142 are changed by an instrument pointer 148 over the marks 144 and 146 runs. A relay control output signal is generated at each set of high and / or low relay output terminals 98 by the relay circuit via a relay switch 150 is closed.

The color monitor arrangement according to the invention thus provides various output signals for adaptation to special applications. For example, weirki dos relay control output signal high and low switch positions as a function of color of the monitored product, whereby the switching processes for the actuation of control lamps, bells, oven valves, etc., can be exploited. In this way, the formation of a feedback correction circuit becomes possible. The analog output signal at terminals 88 can be used, for example, to write coherent curves on a recorder. The digital output signal at terminals 90 can be used, for example, to control a device can be used in digitally designed machining operations. In this context, digital signals can be fed into a computer are fed, which in turn the. Temperature of baking oils, the speed of the conveyor belt, oven temperatures,

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- 24 -material feed valves, etc. regulates.

In Fig. 7, the front of the electronic computer control arrangement 46 is shown. The meaning of the different scales on this front plate results directly from the explanations given above for the circuit according to FIG. 6. The adjustment marks 144 and 146 on the instrument 94 are manually adjusted by knobs 152 and 154, whereby the Upper and lower positions for actuating the relays 140 and 142 are set. In the present case, various calibration processes are described as examples, which before the Commissioning of the inventive arrangement can be carried out in a monitoring process. In the case of a first calibration, it acts it is a "duration" setting or trimming of the divider 54 when assembling the arrangement. According to FIGS. 6 and 7, the function switch 134 is switched to the "run" position. Range switch 136 is toggled to the "one-x" position while speed control circuit 78 is active (Slide 80) clockwise to a quick setup "F" is brought. The switches 162, 166 and 128 (on / off switch, analog switch and digital switch) switched on.

The barrel setting switch 120 is switched to the "G" position, while the gain control circuit 122 is switched to a Voltage of 10 V is set at the analog output terminals 88. The switch 120 is then in the position "B" is switched and the bias control circuit 124 is switched on

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establishes that the same output voltage of IO V arises the terminals 88 results. The above two steps can be repeated.

The barrel setting switch 120 is then switched to the "C" position, and a key pulse with a short rise time of approximately + 2.5 V is applied to a key terminal on the analog / digital converter 92. The trim resistor 120 is set for all "one" output signals on the digital output terminals 90. The divider is thus set to be permanent for overall operation. A second calibration process consists in that the electronic computer control arrangement 46 is adjusted with respect to the specific product to be monitored and the selection of the desired scale shift and the already range settings. For this purpose, the electro-optical observation arrangement 22 arranged above the conveyor belt 14 and the analog, digital and relay switches 126, 128 and 150 are switched off and the on / off switch 162 is switched on (FIGS. 6 and 7). The optical slide 29 (Figs. 1 and 2) is closed to keep light out of the optical system, that is, the photomultipliers 66 and 68 receive no light. When the function switch 134 is set to "Z-Test", the ZD control circuit (bias network 117) is set in such a way that the measuring instrument pointer 148 is at zero. The function switch 134 is then set to "Y setting" and the YD control circuit (bias network 116) is set so that a zero position for the measuring instrument pointer 148 results. The ZD and YD control loops make the electrical

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The output signal (i.e. the color signals) is adjusted in such a way that a "dark" condition arises for the observation arrangement 22 results.

The optical slide 29 is then opened in order to observe via the observation arrangement 22 an optical reference arrangement (not shown) which is located in the viewing area. The optical reference arrangement consists of a plate with a reflection value which is adapted to the product to be observed. For example, for a "light" product, such as potato chips, an optical reference arrangement with a reflectivity on the order of 80 % is used. For a dark product, such as roast coffee, an optical fiducial with a reflectivity of 5 % is used. The function switch 134 is set to the "Y" setting position and the Y gain control network 118 is set so that the full output variable results for the instrument pointer 148. The function switch is then set to the "balance position" and the Z-balancing gain control circuit 119 is set so that the full scale output signal is obtained for the measuring instrument pointer 148.

It is generally desirable at this point to repeat the above steps to eliminate the effects of dark current in photomultiplier tubes 66 and 68.

Then the function switch 134 is in the "run" position

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switched with the optical reference arrangement still present and the meter pointer 148 fully deflecting target. The optical fiducial is then removed and the percentage shift switch 138 is set to a percentage setting which is the lowest expected Value for the monitored product. Then the range setting switch 136 is set to one of the monitoring product corresponding area is set. The arrangement according to the invention is then completely set for the monitoring process.

- patent claims -

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Claims (1)

PATENT CLAIMS Ii method for indicating the light energy which is reflected by a significant in the optical frequency spectrum of product, characterized in that the ratio of two specific, reifektierter from the same area of the product wavelengths is measured, which is a measure for the color of the product. 2. The method according to claim 1, characterized in that the Measurement is carried out over a pair of coaxial optical paths directed to the same area of the product, of the corresponding wavelengths in the optical frequency spectrum, and that an output signal is generated therefrom which is a measure of the is the true ratio of the light values of the reflected light in the optical paths, the ratio being a measure of the reflected energy at the two wavelengths and thus for the color of the product is. 3. The method according to claim 1 and 2, characterized in that an image of a predetermined area of the product is generated and given in predetermined dimensions on a pair of electro-optical transducers, and that of a pair of Color signals generated by electro-optical converters are used to form a ratio representing the reflected light values in the optical paths. - 29 -2098A A / 0845 4. The method according to any one of claims 1 to 3, characterized in that the reflected energy in the two given ratio representing multiple lengths is displayed and that control signals, which are a measure of deviations of the ratio are generated to determine deviations in the color of the product. 5. Color monitor arrangement for carrying out the method η ach one of claims 1 to 4, for the continuous display of the energy produced by one in the optical frequency spectrum illuminated product is reflected, characterized by an electro-optical system (22) for observation of the same Range of the product (18) in a pair of coaxial optical paths of two spectral wavelengths in the optical Frequency spectrum, with the optical paths having light values of reflected energy at the two wavelengths that form a The measure of the color at these wavelengths is and through one coupled to the electro-optical system electrical arrangement (46) for generating a ratio of the light values which is a measure of the reflected energies the wavelengths and thus the color of the product. 6. color monitor arrangement according to claim 5, characterized in that a light source (16) for illuminating the product (18) is provided that the electro-optical system (22) an electro-optical arrangement (24, 26, 28, 30) for Observe the product and continuously generate a pair of in-phase electrical color signals “ which represent the color of the observed product, 209844/0845 _30- and that the electrical arrangement (46) one to the observation arrangement (24, 26, 28, 30, 32, 34, 36, 42, 44) coupled splitter (54) for dividing the pair of in-phase electrical signals to produce a color ratio signal equal to the ratio of the pair of in-phase electrical color signals and a measure of the color of the product being observed, and an output circuit (56, 80, 84, 92) to generate a measure for the color ratio signal and thus for the color of the product Output signal, having. 7, color monitor arrangement according to claims 5 and 6, characterized in that the electro-optical observation arrangement (24, 26, 28, 30, 32, 34, 36, 42, 44) one that is used to observe the product (18) and is reflected. Light from this receiving observation arrangement (24, 26, 28, 30, 36, 42, 44), which an optical Arrangement for forming a pair of coaxial optical lie predetermined dominant wavelengths for the purpose of observation represents the same area of the product, as well as transducers (32, 34) for receiving the light in the coaxial optical paths and for generating the pair of in-phase electrical color signals with magnitudes corresponding to the pair of light values, having. - 31 - 209844/0845 8. Color monitor arrangement according to one of claims 5 to 7, characterized in that the divider (54) is a computer control arrangement (24, 26, 28, 30, 32, 34, 36, 42, 44) coupled to the electro-optical Ebee observation arrangement ( 46) for receiving the pair of in-phase electrical color signals, which includes an analog divider for performing the ratio formation of the pair of in-phase electrical color signals and for generating the color ratio signal, and that the output circuit (56, 58, 84, 92) is designed as part of the computer control arrangement and is coupled to the divider in order to generate an output signal representing a measure for the color ratio signal in a predetermined format. 9. Color monitor arrangement according to one of claims 5 to 8, characterized characterized in that the electro-optical converters (32, 34) serve to record an image of the illuminated product (18) that before the electro-optical converter in the coaxial Because of their formation as coaxial optical paths with predetermined dominant wavelengths, each color filter (42, 44) are arranged and that a synchronizing arrangement (24) is arranged in front of the color filters, which for the same phase The image of the illuminated product (18) given by the optical paths is faded into the corresponding electro-optical converter. 10. Color monitor arrangement according to one of claims 5 to 9, characterized in that the computer control arrangement (46) a Calibration arrangement for setting the color ratio signal to one which corresponds to a desired color reference value 209844/0845 _ ₃₂ _ has a predetermined value, and that the output circuit (56, 78, 84, 92) Deviations of the color ratio signal from the value set by the calibration arrangement records, the deviations being a measure of the color difference between that of the observed product and the desired one Product color are. 11. Color monitor arrangement according to one of claims 5 to 10, characterized in that the electro-optical observation arrangement (24, 26, 28, 30, 32, 34, 36, 38, 42, 44) continues an object arranged in a given optical axis! vlinsensystem (26) has that the synchronizing Arrangement (24) as arranged in the predetermined optical axis coaxially with the objective lens system synchronizing Lens system is formed and that in the predetermined optical axis a beam splitter (36) for forming the over the corresponding color filters (42, 44) directed to the electro-optical converters (32, 34) pairs of coaxial optical Because is arranged. 12. Color monitor arrangement according to one of claims 5 to 11, characterized characterized in that the output circuit (56, 78, 84, 92) has a display instrument (94) for displaying the color ratio signal. 13. color monitor arrangement according to one of claims 5 to 12, characterized characterized in that the display instrument (94) high / low setting point relay (140, 142) for generating an output s igrals, which is a measure of a decrease under and a Rise above a high / low set point. 209844/0845 -34- sy 14. Color monitor arrangement according to one of claims 5 to 13, characterized in that the output circuit (56, 78, 84, 92) has an analog digital converter (92) for generating one depicting a hatred for the color ratio signal Has digital output signal. 2098