GB1326763A - Automatic control device for controlling toner concentration in a liquid developer bath in an electrostatic copy machine - Google Patents

Abstract

1326763 Electro-photographic developing apparatus; automatic control of concentration IWATSU ELECTRIC CO Ltd 26 Aug 1970 [15 Nov 1969] 40986/70 Headings G2H G3R A pump 2 pumps liquid developer from a tank 1 into a bath 3 for developing latent images; through a detector 4 where toner concentration is measured; and through a supply mechanism 6 which is controlled by detector 4 to add toner from a source 7 to the developer. In detector 4 the developer flows down a guide 11 which forms a thin flow of developer. The opacity of this flow is measured by a photo-cell 13 and compared with a standard value indicated by a filter 18 and measured by a photo-cell 19. Any difference between the outputs of the photo-cells is applied by a circuit Figs. 7, 8A, 8B (not shown) to a solenoid (23) which controls an output valve in toner source 7. In Fig.8C (not shown), a source of carrier liquid (54) as well as a toner source (53) is controlled by photo-cells 13, 19. In Figs. 9, 10 (not shown), a float (47) measures the liquid level in tank 1. When the lead falls below a predetermined value, a warning lamp (49) is illuminated and the toner supply solenoid (23) is disabled. The value at which toner concentration is to be maintained may be adjusted by replacing filter 18 or by adjusting a resistor (36) Figs. 8A, B (not shown).