Patent GB-959399-A (GB)
Title: Improvements relating to colour-classifying arrangements
IPC: B07C5/342
Filed: 1960-11-18
Abstract: 959, 399. Photo-electric colour measurements. CONSOLIDATED CIGAR CORPORATION. Nov. 18, 1960 [Nov. 8, 1960], No.39823/60. Heading G1A. [Also in Divisions B8 and G4] A colour classifying apparatus comprises means for producing three first signals X, Y and Z varying in accordance with the tristimulus valves of a colour, means responsive to said first signals producing digital signals corresponding to the   functions Y, X/Y and Z/Y and classifying means responsive to said digital signals. General The invention which is stated to be of general application in classifying objects according to colour is described as applied to an apparatus, Figs. 2 and 3, for sorting cigars. The cigars are delivered from a hopper 33 by conveyers 19, 20 to a transfer mechanism 14 which is rotated intermittently to bring each cigar in turn to the inspection window 39 of a photo-electric colour analyser 13 (see below), against which it is pressed by a lift mechanism 66, 69. Thereafter the cigars are picked up by cradle members 78 on a continuous conveyer 74 and traversed past discharge stations located below the return run of the conveyer. Each station is intended to receive cigars of a different predetermined colour and has an electro-magnetically actuated ejector mechanism 97, 99, 102 which is brought into action whenever a cigar of the correct colour is positioned above the station. In accordance with the invention the photo-electric analyser produces by means of an associated control circuit (see below) a digital colour address signal according to the functions Y, X/Y, Z/Y for each cigar. These signals are transferred stage-by-stage through a magnetic memory store in step with the movement of conveyer 74 and are read and compared with digital address signals for the stations to determine the actuation of the ejector mechanisms. The photo-electric analyser, Fig. 6, comprises a lamp 209, which illuminates the cigar in window 40 by way of parabolic reflector 211, and a photoelectric cell 213 responsive to reflected light. A filter disc 203 mounted on a shaft 201 is rotated to introduce Y, X and Z filters in turn into the light path, the disc also carrying a further Y filter which appears after the colour measurement on the cigar is completed and serves in conjunction with a light reflecting disc 206, also rotated by the shaft 201, to produce a reference level signal in the photo-electric cell. The shaft also carries a disc 202 having a series of radially and angular displaced slits 207 A-F which function to expose photo-diodes 208 A-F for the purpose of providing signals cynchronized with the shaft rotation for use in the control circuit. Control circuit Fig. 11 (not shown). The digital signals are produced by a multi-state digital register which is stepped to its various states in succession by pulses from a clock source and controls a digital to anglogue converter to generate of voltage increasing progressively as the register steps. The voltage is compared with the voltage from the photo-electric cell in the analyser and the stepping of the register terminated when the two are equal. The final state of the register thus indicates the cell signal in digital form and is held prior to entry in a magnetic store (see below). The first signal to be converted is the Y signal which at the completion of the conversion is stored by means of a second register and digital-to-analogue converter. The stored Y signal is then supplied as a reference signal to the first digital-to-analogue converter which functions during the following X and Z signal in such   manner as to generate the signals X/Y and Z/Y. At the completion of the Z signal conversion, the three digital signals, which (in the particular embodiment described) together form a six digit signal, are entered in a magnetic store as an address indicating the colour of the measured cigar. Prior to each digital conversion, the register is stepped to its maximum and minimum states and the resulting analogue voltages compared with the photoelectric cell signal. This is done to determine whether the signal falls within the maximum and minimum limits. If it falls outside, a registration is entered in a counter and provision is made to enter in the magnetic store a digital address which ensures the rejection of the cigar. Means are provided for adding to the signals Y, X/Y and Z/Y D. C. signals, K 1 , K 2 , and K 3 , respectively which are made adjustable so that the signal levels required to produce particular digital signals may be controlled. Means are also provided for adding to each signal a voltage to compensate for dark current determined by inserting a black surface in the inspection light path. The Y reference level signal which appears following the Z measurement is compared with a reference voltage and applied through an integrator to control a regulated power supply for the photo-electric cell 50 as to stabilize the operation against variations in the photo-electric cell and lamp. At the completion of the measurements on each cigar, the six digit signal representing the colour is entered in a magnetic store. A cycle of operation is then initiated in which the existing entries in the store are advanced through one position corresponding to a single increment of advance of conveyer 74. The entries are advanced in sequence, one at a time, starting with the oldest, by a process in which the entry is read out, compared with a digital address representing the station against which the cigar represented by the entry is located, and then (with the exception of the oldest) re-entered. Whenever the store entry corresponds to the station address, thus indicating that the related cigar is of the colour allotted to the station, an entry is made at an appropriate position in a temporary magnetic store having one position for each station. At the completion of the cycle, when all the store entries have been compared and advanced, the temporary store is then triggered and supplies signals to control the electromagnetic ejector mechanisms.