Patent GB-1391221-A (GB)
Title: Electronic system and method for capsule inspection
IPC: G01N21/90
Filed: 1972-09-26
Abstract: 1391221 Counting capsules ELI LILLY & CO 26 Sept 1972 [27 Sept 1971] 44437/72 Heading G4D [Also in Division G1] Medicinal capsules are inspected photoelectrically as they are spun on their own axis and defects in their surfaces are distinguished from predetermined deformations by differences in the timing of pulses in the detector output. In Fig. 3, capsules picked-up at a loading section by suction are rotated in steps to an inspection location where a number of photocells are used to deliver outputs on a plurality of lines (see Fig. 10), representative of different parts of the capsule. Defective capsules are ejected into 108 and acceptable ones into 110. In the circuit system of Fig. 10, the detector outputs are amplified in preamplifiers 112-118, and pulses above a certain level passed on by processors 120-126. Accumulators 128-133 are set to produce an output when they exceed a count of, e.g. four, if the number of rotations of a capsule is five. This allows a defect to be missed once only in the five rotations. In the channels including preamplifiers 116, 117, there are provided the means to distinguish defects, e.g. cracks, cuts, deformations &c. from the preformed lands used, e.g. for locating the capsules during filling. The latter produce pulses occurring at predetermined intervals in the detector output and counters 136, 138 are set to count clock pulses up to values representative of these intervals and then to reset. If a defect pulse occurs this resets the counter early and produces an output to the accumulator 132. If one, at least, of accumulators 128-133 has a predetermined type of output a decision to reject the capsule is made at 147, otherwise the accept counter adds one. The reject signal is inhibited at 144 until the complete inspection has been executed to ensure that the capsule is complete. The reject signal can then be shifted through register 148 under the control of 160. Counters 150, 152 provide counts of the number rejected and the percentage of rejections. Accumulators 128-133 are reset before each capsule inspection under the control of synchronization pulse generator 154. Circuit details.-The photo-cell preamplifiers and processing circuits comprise operational amplifiers, Figs. 11, 12 (not shown). The synchronization pulse generator is an index sheet, Fig. 15 (not shown), rotating in synchronism with the drive shaft of the inspection head, to interrupt light reaching a photo-transistor once for each revolution of the shaft. The output of the detector transistor amplifier is passed by monostables in the units 156, 158, 160, Fig. 14 (not shown). The counters 136, 138 may be of the type illustrated in Fig. 13. Pulses from clock 140 are counted until a predetermined count or an input from 124 is obtained when it is reset. Defect indicative output is produced only if the counter is reset by defect pulses forming before the predetermined count set in BCD switches (290-293). The accumulator array 128-133 and blocks 142, 147, 148 are detailed in Fig. 14. The accept and reject counters are of mutually identical form, Fig. 17 and include a nine tube display and an alarm facility when a preset count is exceeded. The rejected capsule ratio is calculated by the circuit of Fig. 18 which displays the number of capsules rejected per thousand inspected and includes a flashing lamp or audio alarm if the ratio goes above a predetermined value. The detectors may be a self scanning array of photo-diodes whose outputs are analysed serially.