ES380377A1 - Multiple optical filter apparatus - Google Patents

Abstract

An optical filter apparatus 20 for selectively inserting an optical filter into a moving light beam of an optical system, for example a photo-copier, comprises a plurality of optical filters 26, means to insert a selected one of the filters into the light beam and means to move the apparatus so as to maintain the selected filter in the moving light beam. Each filter is mounted in a frame 27 slidable in tracks 24 and 25 in a housing 21, and each frame has an arm 50 protruding through a slot 49 in the housing. A pair of springs 30 and 34 biases each frame to the left, where it is inserted into a light beam passing through window 23, and in each track 24 there is a stop (37), Fig. 6 (not shown), which is biased upwards by a spring (54) to retain the frame out of the window. Each stop (37) may be lowered by means of a solenoid to release a selected frame. The apparatus 20 is then moved with the light beam, for example to scan a document to be copied, and when the scan is complete it is returned to its original position by means of a spring (not shown). As it returns, roller 56, which is carried by an arm 57 connected by a spring-biased lost motion connection to an arm 40, engages a cam (55), Fig. 4 (not shown), to turn the arm 40 anticlockwise about pivot 41 so as to engage the arm 50 of whichever filter is in use and return it to the right, where it is retained by stop (37). The operation is then repeated with each of the filters in turn to give, in the embodiment, a threecolour reproduction of a document. The apparatus 20 may also carry with it a lens assembly (15), Fig. 3 (not shown).