| 摘要 |
1,008,131. Photo-electric position finders. ALBISWERK ZURICH A.G. Feb. 7, 1964 [Feb. 7, 1963], No. 5233/64. Heading H4D. In the kind of photo-electric position finder having a reticle chopping the received radiation before it reaches the photo-cell, a known reticle pattern (Fig. 6, not shown) comprising zones 10, 11 is modified by the inclusion of a transition region 16 having an axis 9 oblique to the direction of pattern motion and incorporating alternate radiation-transparent and opaque strips those of which adjoin zone 10 having a width measured in the direction of motion equal to the width of " gaps " and " spokes " in zone 10 and those of which adjoin zone 11 having a width measured in the direction of motion equal to the width of gaps and spokes in zone 11. The reticle may be a disc or a loop. The pattern of the invention permits the instant of pulse-frequency change, from which the co-ordinates of the object are derived, to be determined more accurately. |
