GB292474A - Improvements in apparatus for sorting or classifying articles by means of light - Google Patents

Abstract

292,474. Westinghouse Electric & Manufacturing Co., (Assignees of Zworykin, V. K.). June 16, 1927, [Convention date]. Alarm, indicating, recording, and registering apparatus. - Relates to apparatus for sorting articles by means of light sensitive devices which are subjected to the light reflected from the surface of the articles the electric energy so developed being utilized to actuate the means for segregating the articles, and consists in the provision of a series of such light sensitive devices which are adapted to scan successive portions of the articles as they move. past. The application of the invention is to the inspection and sorting of tin-plated or galvanized sheets, paper, cardboard, fabrics &c. In the apparatus described, the sheets 43, Fig. 1, are conveyed by rollers 2 past the inspection device which consists of a transversely arranged box 8 containing a number of photo-electric cells 31, Fig. 3, and a linear source of light 9 contained in a casing 10. The light reflected from the sheets is passed to the cells, a reflecting surface 44 being provided to prevent actuation of the apparatus during the intervals between the sheets. Preferably the cells are arranged in series in two groups 50, Fig. 4, forming with variable resistances 53, 54 the elements of a Wheatstone bridge. A source of high potential 55 and a thermionic valve 56 are arranged across the network which is balanced so that the filament 57 and grid 58 are at the same potential, when the reflected light has a predetermined intensity. When a defective part of the sheet passes under any one of the cells, the balance is disturbed producing a current in the plate circuit of the valve which is amplified by the device 12 and energizes a solenoid 14, the armature of which closes the contacts 16, 17. The delivery table 6 of the device is hinged and is normally held in the position shown by a solenoid 7 energized by the battery 25. When the contacts 16, 17 are closed, the solenoid is partly deenergized and the table drops by its own weight, the armature closing contacts 30 in a second shunt circuit which is provided so as to maintain the table in the set position until released by the timed opening of this circuit by the cam or other device 28. The Specification as open to inspection under Sect. 91 (3) (a) comprises also a modification; the apparatus may be adapted for inspecting fabrics and like materials by transmitted light, the variations in which may be caused to operate an audible signal and stop the machine. This subject-matter does not appear in the Specification as accepted.