| 摘要 |
PCT No. PCT/GB91/01306 Sec. 371 Date Jan. 13, 1993 Sec. 102(e) Date Jan. 13, 1993 PCT Filed Aug. 1, 1991 PCT Pub. No. WO92/03683 PCT Pub. Date Mar. 5, 1992.A pan and tilt head for a TV or video camera mounting (10) comprises two drag/damper devices, one for controlling the pan movement and the other for controlling the tilt movement. Each device may comprise a fixed central shaft (18), a first set of spaced plates (22) secured to the shaft, a second set (24) secured to a rotatable housing (20), and a third set (26) interleaved between the first and second sets. When the plates are immersed in a viscous fluid and one member is moved, the characteristics are such that the forque increases linearly with speed from zero up to a given speed, and then remains substantially constant above the speed.
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