GB1239781A - Regenerating means for a continuous photographic developing apparatus - Google Patents

Abstract

1,239,781. Control of D.C. motors. AGFA-GEVAERT A.G. 10 July, 1968 [11 July, 1967], No. 32822/68. Heading H2J. [Also in Divisions G2 and G3] Fresh processing liquid is supplied to a continuous photographic developing apparatus by a dosing pump driven by a variable-speed motor 64, the speed being varied in correspondence to the width of material being processed as sensed by switches 11-19 in the speed control circuit of the motor, each switch and an associated resistor 33-41 being connected in parallel. The motor is a direct-current motor with permanent field magnetization, and the speed is regulated by the current derived from a tachogenerator 63 fitted on the motor shaft. During operation, a change-over switch 6, controlled by a rotating cam on the drive arrangement for photographic material through the apparatus, periodically discharges capacitor 5 through a relay 8 to close contacts 8a and bridge the thyristor 78. After capacitor 5 is discharged, contacts 8a open again and relay 61 drops out, closing contacts 61a and opening contacts 61b. The motor 64 then runs at a speed depending upon the voltage drop across resistor 57 and until thyristor 78 fires at a time determined by timing circuit arrangement 70-77. A basic control of the motor independent of the width of the material is given by relay 21 when energized closing contact 21a. A manual switch 20 enables supply of fresh processing liquid to be manually pumped, the resistor 43 being selected to give a maximum pumping speed. The closing pump, Fig. 2 (not shown), has a camshaft (81) having three control cams (82a, 82b 82c) operating diaphragm pumps (83), (84), the quantity of fluid pumped per stroke being regulated by screws (85), (86).