| 摘要 |
1,136,648. Control of D.C. motors. GENERAL ELECTRIC CO. 27 April, 1966 [23 June, 1965; 28 June, 1965], No. 18562/66. Heading H2J. [Also in Division G1] A photo-rheostat of the type in which a control device varies the amount of light passing to a photo-resistor is provided with means for disabling the controlling effect of the photoresistor when the control device is at the ends of its range of adjustment. The control device may be a cam operated shutter 15, Fig. 3, movable in a slot in a housing 16 containing the lamp 17 and a CdS photo-resistor switches 20, 21 operated by a bar 13 and the shutter 15 respectively disconnect the photo-resistor output from the controlled circuit and apply an open and short circuit at the ends of the range of rotation of the rod 10. In another embodiment, Fig. 6, (not shown), the rod 10 rotates a housing containing the lamp 30 and a polarizer 29 so that the amount of light passing through the polarizer 31 to the photo-resistor 32. The limit switches are operated by arms 26. The photo-rheostat may be connected in a potential divider connected to the control electrode of a silicon controlled rectifier (SCR). The SCR is in series with a D.C. motor and is fed by chopped D.C. The photo-rheostat thus controls the mean motor current. |
