Patent GB-900761-A (GB)
Title: Camera
IPC: G03B19/18
Filed: 1960-07-15
Abstract: 900,761. Kinematographic two-speed cameras. BELL & HOWELL CO. July 15, 1960 [Oct. 5, 1959], No. 24699/60. Class 97 (I). A motion picture camera having an automatic exposure control device for adjusting the diaphragm in dependence on the illumination has a manual control member which operates means for starting and stopping the camera drive and which selectively operates a speed control means for the camera drive thereby to select either of two-speeds and at the same time operates means which, in dependence upon the speed selected, adjust the exposure control device accordingly. As shown in Figs. 1 and 16, a slide member 41 is manually operable from outside the camera by means of a button 35 attached to lug 41a, whereby it may be moved upwardly or downwardly from a " neutral " position 37 in which position the lug 41c engages and holds (see Fig. 4) an arcuately-formed lever arm 51, pivotable on pin 52, so that a lug 51b formed thereon and projecting through an opening in the mechanism mounting plate 53 engages lugs 54a of a gearwheel 54 forming part of the camera drive to lock the latter. Upward movement of button 35 from position 37 to position 38 allows rotation of gear-wheel 54 sufficient to expose a single frame. Downward movement from position 37 to 39 causes clockwise pivoting of lever 51 to bring lug 51c into engagement with a sliding plate 58 without moving the latter. In this " normal speed " position, plate 58 constrains entirely within a sleeve 83 a ball 84 (Fig. 11) which, in a manner described below, adjusts a brake member 81a of a speed governing device 69, linked via gear-wheel 60 to the camera-drive mechanism, to become operative to produce a predetermined braking effect corresponding to normal speed operation. Further depression of button 35 to " slow-motion " position 40 causes lug 51c of lever 51 to move plate 58 to the left, thereby bringing an aperture in plate 58 into alignment with the ball 84 which is thus allowed to project slightly from the sleeve 83, thereby allowing a higher speed of the camera drive under the control of a second brake member. The speed governor operates as follows. On a shaft 63 two rotor members 62, 61, of which the latter is geared via gear 60 to the camera drive, are splined together by rods. Rotor 62 has a cup-shaped recess with a shoulder 62d formed therein and is held by spring loading 67 against four balls 68 (only two shown) located by recesses in rotor 61. Rotation of rotor 61 by gear 60 is transmitted to rotor 62, freely mounted on shaft 63, via the balls 68 which move radially outwards under centrifugal force and exert axial force on the shoulder 62d, whereby rotor 62 is displaced axially until, as shown in Fig. 11, it engages brake member 81a to give " normal " speed, the balls 68 being constrained by shoulder 62d. When, in the high speed or " slow motion " setting ball 84 can project from sleeve 83, rotor 62 is allowed increased axial movement, since brake member 81a can be displaced to follow ball 84, thus allowing balls 68 to clear shoulder 62d and rotate with greater velocity, the balls 68 being now held by projection 62e on which the axial component of force is smaller than in the case of shoulder 62d. Rotor 62 is now braked by a second brake member 87. The larger diaphragm apertures which are necessary at the higher speed of the camera drive are obtained by pivoting of an electrical contactor by the part 41c of slide member 41 as the latter is depressed, whereby additional resistance is introduced into the galvanometer circuit of the exposure control device, thus reducing the output to the diaphragm mechanism. A three-lens rotatable turret is provided with notches engageable by, a spring member which, when there is no proper alignment of a lens, is held pressed into the interior of the camera where it causes locking of the slide member 41.