Patent GB-916522-A (GB)
Title: Improvements in or relating to optical slide projectors
IPC: G03B23/00
Filed: 1960-11-02
Abstract: 916,522. Magazine slide changers. KODAK Ltd. Nov. 2, 1960 [Nov. 2, 1959], No. 37679/60. Class 97 (1). [Also in Group XXIV] An optical slide projector includes a slide magazine and means for automatically advancing the magazine step-by-step and removing therefrom a slide to a projection position and returning it to the magazine, and also means operated by part of the magazine at the end of its run to automatically return the magazine to its starting position. As shown in Fig. 3 a slide magazine 3 is movable along a guide-way 2 by moans of a pinion 46 engaging a rack on the magazine and driven through a dog-clutch 35. The driving member 36 has a multiplicity of teeth so that the dog 37 can connect in any position. The driving member 36 is movable for disengagement on the spindle 34 against spring loading by means of armature 39 of solenoid 41 when the latter is energized, but is normally held in engagement by spring 44 to impart to the magazine a well-defined intermittent movement derived from the engagement of a gearing 33 with gear 32 carried on the member 29 of a Geneva mechanism (Figs. 1 and 8) intermittently driven by pin 28 carried on a gear 27. The latter is driven by shaft 11, through worm 8 on the spindle 7 of a motor 6, when the spring clutch 17 is engaged. The spring clutch 17 is disengaged by the arrest of one of its projecting ends by an electromagnetically-operated arm when, at the end of the magazine run, a switch 86 (Fig. 9) is operated by one of the projecting portions 88 at either end of the magazine. A connection at A is thus broken and one at B closed to prime a circuit for the operation of a switch 84 (see below) and to energize solenoid 19 to activate the said arm disengaging the spring clutch 17. At the end of the magazine run, a cam-driven slide-lifting- and retuming-mechanism 75-79 can engage and close switch 84 to energize solenoid 41 and disengage clutch 35 whereby pulley wheel 38 is freed and enabled to turn freely under the constant driving torque of belt 73 which prior to release of pulley 38 from the advance-and-lock mechanism slipped on the pulley. (The belt is continuously driven from shaft 7 via worm 8 and gearing 9(12), 48(51), 52, and 69, the latter gear being integral with shaft 71 to which the belt-driving pulley 72 is fixed.) Pulley 38 is integral with pinion 46 and the magazine is thus returned automatically to its initial position. The other one of the two projections 88 is now operative in re-setting switch 86 for another advancing sequence. The time-interval between successive strokes of the Geneva mechanism can be varied to allow different viewing times for the slides by means of a 4-lobed cam 59 manually rotatable about axis 61 whereby the spring-loaded gear 52 can be axially displaced by varying amounts and thus bringing varyingly-spaced projections around, and at different heights on, the periphery of a wheel 57 rigid with gear 52, into operating relationship with arm 66 of a toggle switch 67. The latter controls the energization of solenoid 19 to cause engagement and disengagement of spring clutch 17 at a frequency determined by the particular arrangement of active peripheral projections corresponding to the chosen setting of cam 59. In one setting of cam 59 no projections will engage arm 66 and the projector is then under manual control. The slides are mounted in holders having two ears which can be engaged on their undersides by corresponding lifting lugs of the slide-lifting- and returning-mechanism 75-79. Specification 899,932 is referred to.