GB842115A - Improvements in or relating to measuring apparatus - Google Patents

Abstract

842,115. Photo-electric measuring. LEBAR, M. L. March 4, 1957 [March 3, 1956; Feb. 25, 1957], No. 7159/57. Class 40(3). [Also in Group XXXVIII] Measuring apparatus comprises a member angularly displaced by the measurement to rotate another member which produces impulses which are detected photo-electrically and counted electronically, a mechanical movement amplifier being interposed between the measuring member and the rotary member to effect a plurality of revolutions of the latter for one complete travel of the former. A weighing machine beam 1, Fig. 1, is pivoted at 5 along with a lever 4 on which is pivoted another lever 7. At rest, levers 4 and 7 are held together by a permanent magnet to make contacts at their ends. In operation, beam I revolves around its pivot 5 to lower a rod 13 which through a toothed segment 15 and pinion revolves a spindle 16, Fig. 3, of a gear box 22 the input shaft of which is driven by a motor 21. An output shaft 17 which performs one hundred revolutions to every revolution of the shaft 16 carries a perforated disc 20 designed to interrupt the light from a source 18 falling on a photo-electric cell 19. The motor 21 is then started manually and the disc 20, starting from a zero position, turns until the levers 4, 7 regain contact to interrupt the supply of current to the cell 19 and cut off the motor. Since the motor does not stop instantaneously levers 4 and 7 come out of contact to return when the motor is reversed by the breaking of contacts 11, 12, to return the arm 4 to zero position. During the downward movement of the arm 4 the disc 20 revolves to an extent proportional to the weight under measurement allowing a number of impulses of light from the source 18 to fall on the cell 19 through the perforations in the disc 20. The zero position of the disc may be determined by the coincidence of two slots, one on the disc and the other on another co-axial disc driven at a different speed (Fig. 8, not shown, refers). Pulses from the photo-cell are fed to an electronic counter where they may also be registered or printed. A wheel 31, Fig. 11, 1, engages with teeth 33 to position a printing wheel 80. Contact arm 36 wipes studs 37, one of which is energized to represent the numeral. Upon energization an electromagnet 39 clamps the wheel through the action of a pawl 35. When a full sensing sweep has been made a striker 102 prints the numeral. A number of wheels 31 are revolved by a common driving shaft through brass and nylon washers (Fig. 12, not shown). A positive drive may replace friction drive, as described with reference to Fig. 13 (not shown). In another embodiment a plurality of perforated discs driven at different speeds representing various ratios is employed to register cost as well as weight. Applications to liquid fuel dispensers and electrical indicating instruments are also mentioned.