| 摘要 |
1312428 Windscreen wipers ROBERT BOSCH GmbH 10 March 1972 [13 March 1971] 11206/72 Heading A4F [Also in Division H2] A parking device included in a drive mechanism for windscreen wipers comprises a permanent magnet whose circular path, when mounted on a worn gear driven by motor 10, leads past a magnetic field dependent resistor 38. Maximum magnetic field at the resistor 38 occurs when the wipers which are driven by the motor 10, are in their parked position. Closing of a manual switch 21 actuates the motor 10 via a switch 23 in a relay 20. As the magnet moves away from the resistor 38 the resistance of the resistor 38 decreases causing a transistor 34 to become non-conductive and a second transistor 31 to become conductive thereby by passing the manual switch 21 since the line containing elements 26, 24, 32, 31 and 33 is continuous. On manually opening the switch 21, the motor 10 continues to operate by virtue of the by-passing through transistor 31 until the magnet 40 again increases the resistance of the resistor 38, i.e. when the wipers are in their parked position. The transistor 34 then becomes conductive thereby causing the transistor 31 to become non-conductive and hence de-activating the relay 20 causing the motor 10 to stop. |
