| 摘要 |
1,268,998. Escapements. BELL & HOWELL CO. 17 Aug., 1970 [2 Sept., 1969], No. 39526/70. Heading F2X. [Also in Divisions G2-G3] In a cine camera, zoom lens 16 is controlled by pivoting lever 60 up or down about shaft 50 to tilt a motor-driven reciprocating pawl 22 about shaft 50 whereby either arm 38 or 40 of the pawl intermittently engages toothed tracks 24 on a rotatable wheel 18 connected to zoom ring 28 to provide forward or reverse rotation thereof. Pawl 22 is slidably mounted on an eccentric hub of a gear 44 continuously driven by camera motor 57. Lever 60 has an arm 62 with which a third arm 58 of pawl 22 is aligned by spring 64, and the lever may take a central position in which neither arm 38, 40 can engage tracks 24. In another embodiment, pawl 22 has only the two driving arms 38, 40, one of which is linked to the actuator lever 60. In another form, gear 44 may be rotated in opposite directions by using a separate reversible motor to drive pinion 54. Lever 60 and control knob 84 are here omitted, since the pawl 22 automatically takes up the required tilt as the motor reverses. In the first two embodiments, the gear 44 may be synchronized with the shutter frequency. |
