Patent GB-634606-A (GB)
Title: An improved anti-glare or dimming device for lamps such as the headlamps of motor and other vehicles
IPC: B60Q1/14
Filed: 1947-10-02
Abstract: 634,606. Anti-dazzle device for head-lamps. ROBINSON, D. U. Oct. 2, 1947, No. 26598. [Class 75 (iv)] [Also in Group XXXV] A dimming device for motor vehicle headlamps comprises a plurality of light diffusing flaps 9 of truncated sector shape each mounted for simultaneous partial rotation through control means about a radial edge so that in one position the flaps form a frusto-conical screen between the reflector 1 and the front glass 3 and in another position the planes of the flaps are substantially parallel to the projected light. The device can be fitted to existing vehicle lamps. The flaps, which are preferably made of frosted mica, made according to the process described in Specification 238,778, [Class 70], are mounted on a framework comprising a central bearing assembly 6 secured by three radial supports 7 to an annular member 5. The device is secured in the casing of a head-lamp by clamping the annular member 5 between the edge of the reflector 1 and the front glass 3, the assembly 6 being located forwardly of the annular member 5. The central bearing assembly 6 comprises a fixed frusto-conical cup 12 provided with holes 30 in its side wall serving as bearings for the ends of shafts 17 to which the flaps are attached, and a rotatable bearing plate 13 substantially enclosing the fixed cup 12 and provided with slots 15 through which cranked portions 18 of the shafts 17 pass. The cranks 18 are adapted to cause simultaneous rotation of their shafts and flaps when the plate 13 is rotated. At their outer ends the shafts 17 are located in bearings formed by drilling holes in folded inclined lugs 8 provided on the annular member 5. The plate 13 rotates about a central pin 11 in the bearing assembly 6 and its rotation is limited to correspond to a 90 degree rotation of the flaps by a pin 24 on the fixed bearing cup 12 engaging an arcuate slot 25 in the plate 13. The flaps are actuated from the driver's seat through means comprising a solenoid 23. One of the shafts 17 (a master shaft) extends through the reflector 1 and is linked to the armature 22 of the solenoid by a lever 21 secured to the end of the master shaft and an arm 38 projecting from the armature of the solenoid. The outer bearing for this master shaft is formed by a slot transverse the fold of a doubled-back lug on the annular member 5 and a pin is inserted in the fold to keep the shaft in position. The solenoid 23 (Fig. 2) comprises a central armature-guide tube 42 which extends beyond the end cover 44 of the winding 39 and has a slot guiding the arm 38 attached to the armature 22. A spring 25 attached to a slotted extension 43 of the casing holds the armature in its outermost position corresponding to the flaps being disposed parallel to the projected light. The winding 39 is of low resistance and is connected in series with the dimbright switch and the dim light. A pair of contacts 36, 37 are arranged to shunt the dim light when the armature is at its outermost position but are adapted to be opened by the arm 38 when the armature is in its innermost position. Thus, when the dim-bright switch is depressed to dim the lights the winding 39 is energized momentarily by a relatively large current causing the armature to strike the solenoid core 41 and causing the arm 38 to open the contacts 36, 37 and to move the flaps into their dimming position. The mechanism is held in this position by the winding being energized by the normal dim-light current. Alternatively fluid pressure means or Bowden cable may be used for actuating the flaps. In an alternative construction for connecting the rotatable plate with the shafts 17, pins on the plate engage in slots in arms projecting from the shafts.