GB1384714A - Rearview mirror - Google Patents

Abstract

1384714 Photo-electrically controlled rear view mirrors D H BALDWIN CO 31 Dec 1971 61066/71 Heading B7J [Also in Division G1] A photo-electrically controlled rear-view mirror which is moved automatically from a position in which the driver is being dazzled to one in which he is not, is provided with further photo-electric means monitoring ambient light conditions so that the automatic operation may be blocked during day light hours. Construction.-Fig. 1 (not shown) indicates the general arrangement of the mirror with centrally located bracket 13 mounting the arrangement to the vehicle frame. The principal members that are mounted by the bracket (by ball 51) are plates 45, 47 which form a socket therefore. The housing 17 itself (and members supported by the housing) is attached to plate 45 by pivot arrangement 46. When electromagnet 31 is so energized (under control of a photo-electric circuit) that it attracts permanent magnet 39 and repels 37, the cam arrangement 61-65 being carried to the left (Fig. 4A) so that projection 53 on plate 47 is in slot 63, the front surface 23 of mirror 23 is effective in the driver's field of view (Fig. 3a). When a different intensity of light is sensed by the photo-electric circuit, the electromagnet current is reversed and projection 53 is drawn up sloping cam surface 65 into slot 61, at the same time the mirror housing being tilted about 46 to render back surface 25 of the mirror effective in the driver's field of view. Cam 55 and projection 53 may be of plastics, low friction material. The securing of each position of 53 may be aided by spring 67. Manual movement of mirror is possible by means of actuator (69). Circuit.-As shown in Fig. 5, P 2 is a photoresistor which is positioned to view out of the side of the mirror away from oncoming traffic, to monitor ambient light intensity. When it is below a certain level, set using potentiometer R 15 by the driver, the photo-cell P 1 is enabled to operate. When this senses a high intensity, transistor T 7 is turned on and T 8 off to render T 1 conductive. The two-state circuit T 2 -T 6 is therefore so switched that the current in the electromagnet coil M 1 is in the direction to cause tilting of the mirror. (In this condition T 2 , T 3 on; T 4 -T 6 off). Low intensity on P 1 results in the reverse operation and current direction through M 1 . Transient light effects are reduced by capacitor C 1 . In an alternative circuit, Fig. 6 (not shown) two SCR's replace T 2 , T 3 and T 4 , T 5 .