GB967456A - Dimming device for optical projectors - Google Patents

Abstract

967,456. Optical projector dimming devices. VOIGTLANDER A. G. Oct. 27, 1960 [Oct.28, 1959], No. 36997/60. Heading G2J. An optical projector having a lamp and a concave reflector includes a dimming device comprising a cover which can be introduced between the lamp and the reflector and at least one other dimming member consisting of less than fully transparent material interposable in the light beam between the projection aperture and the objective. As shown, a spring-loaded lever 14 pivoted at 114 carries an opaque cover 11 and, upon energization of electromagnet 21 by pressing one of the switch-buttons in a switching box 25, escapes from the spring-loaded locking pawl 18 as the latter pivots anti-clockwise under magnetic attraction, the cover 11 riding up in guide 16 between reflectors 3 and lamp 2. In an exactly similar fashion neutral filters 12 and 13 carried on levers 27 and 35 respectively, both of which are pivoted at 28, may be introduced, by means of springs 29 and 36 acting on the respective levers, into the projection beam path, upon depression of further switchbuttons. The various buttons may be characteristically marked, for example by different luminous markings or relief patterns, such as pimples, for detection by touch. The switching box 25 may also contain switching controls for the projector. Slides or transparencies 7 stored in a magazine 10 may be pushed into and withdrawn from the gate 6 by means of a slide member 8. The latter carries a lug 26 which, on withdrawal of the slide 8 bears against the upper edges of the levers 14, 27 or 35, as the case may be, and depresses them on to the sloping heads of the locking pawls which are thereby pivoted against their spring loading and finally snap back to lock the levers. The levers may be operated separately or in any combination. In an alternative embodiment, the levers are arranged above the optical system and are gravity-operated when the locking pawls are released.