GB470134A - Improvements in or relating to photoelectric photometers - Google Patents

Abstract

470,134. Photometers. WESTONELECTRICAL INSTRUMENT CORPORATION. July 8, 1936, No. 18952. Convention date, Aug. 16, 1935. [Class 40 (iii)] [Also in Group XXXVI] In a photo-electric photometer the photo-electric cell is substantially smaller than the scale plate over which the pointer of the measuring instrument moves, and is disposed within the area of the plate. As shown the scale plate 26 disposed behind a glass cover 31 has a rectangular opening in which a barrier layer photo-electric cell 27 is disposed so as to be affected by light passing through the opening. The measuring instrument comprises a magnet 3 held on bosses 45, 5 on the base of the casing by bolts 9<1> and a clamp 7, and carrying a brass bracket 11 supporting the coil 16. The bracket is held by the bolts 9<1> which pass through ears 12, Fig. 7, and carries flanges 13, 14 receiving the jewel bearings of the coil 16, and also has a slot 17 in which the lug 18 of a magnetic core 19 is inserted and beaded over. The scale plate 29 forms the outer terminal of the cell 27 and is connected, via the casing, to one end 23 of the coil 16, the other end 22 of the coil being connected by a lead 47 to a spring backing strip which is insulated from the casing and which holds the cell against the plate 29. The pointer 24 of the instrument moves over the scale plate which is graduated in differently coloured blocks 25a, 25b, &c. corresponding to ranges of light-values. According to the Specification as open to inspection under Sect. 91, the range of light values for each block may increase towards the upper scale limit, and the sensitivity of the moving coil system may decrease towards the upper scale limit so that small light values may be read accurately. This subject-matter does not appear in the Specification as accepted.