GB1406390A - Mechanism for stopping a contact screen at a predetermined position in a process camera - Google Patents

Abstract

1406390 Screen mechanism DAINIPPON SCREEN SEIZO KK 25 Sept 1973 [6 Oct 1972] 44810/73 Heading G2A A half-tone contact screen for a projection copier is raised into operative position on at least one slider, raising almost to operative position being effected by electrically powered driving means and being completed by a rocker member without further action of the driving means by virtue of play between the driving means and the slider. As shown, a selected half-tone screen carried by a respective bar 10 is raised on a pair of sliders 7 (one being shown), each slider having a recess within which is situated, above a stop 17, an operating member 13 pivotally connected at its ends to the slider and a driving chain 15 to provide play therebetween. The driving chain is stopped before raising is completed by contact with a switch 29 by a rocker member 20 on the commencement of its clockwise rotation (as shown) effected by a pin situated between extension plates 11 and 12 of slider 7. Further rotation of rocker member 20, effected by a spring 26 attached to an arm 21, completes the raising operation (without further movement of chain 15) by an upward hooking action on pin 23, the movement being terminated by contact of plate 11 with a stop 27. On lowering of the screen, the rotation of rocker member 20 is reversed, its movement being terminated by a stop 28. In another form, Fig. 4 (not shown), the play is between chain sprocket wheel 16 and its rotary shaft.