GB1196771A - Range Finders. - Google Patents

Abstract

1,196,771. Photo-electric distance measurement. EASTMAN KODAK CO. 25 May, 1967 [31 May, 1966 (2)], No. 24382/67. Heading H4D. [Also in Divisions G2-G3] A range finder especially for use in a photographic camera or projector has a pair of distance triangulating units one of which includes a light source emitting visible or non-visible radiation for projecting a beam of light along a first path towards an object to produce an illuminated area and the other of which includes light sensing means, for producing a signal when in alignment along a second path with the illuminated area. As shown, a camera objective lens 10 is movable with plate 13 for focusing an image on receiving surface 12, the lens 10 being moved as a function of object distance. A second lens 16 projects a beam of light along axis 20, such that the beam impinges the object at 37. A third lens 21 receives light along axis 25 and focuses on a photo-electric device 23, which may be a vacuum tube, a photoconductive or photovoltaic cell. The lens 21 and device 23 are carried by a plate which is rotated about a shaft 26 by a motor 33 through gearing 34, 35, 36 and connecting rod 28. Thus, the device 23 scans the axis 20 between points 38 and 37 to detect the illuminated area of the object. A cam 42 engaging arm 40 adjusts the position of plate 13 with respect to pins 14, thereby focusing lens 10. A solenoid 50 is energized, upon detection of the illuminated area, through a transducer 44 in circuit with device 23 to open a switch 54 to de-energize motor 33 and engage a tooth 55 with gear 35. A pointer 56 indicates the object distance on a scale 61. In another embodiment, Fig. 2 (not shown), a photo-cell (83) and a light source (81) are carried by plates (85) (86) actuated by a cam follower (97) engaging a cam (98). The range finder may be responsive to the depression of a camera shutter release (120), Fig. 3 (not shown), firstly to focus lens (121) automatically according to the distance between the camera and object and thereafter to actuate the shutter. Lens housing (125) is threaded in ring (126) and is rotatable by a gear (128) driven by an electric motor (133) or rotated manually. A rotatable mirror (141) performs the scanning in this case until gear (128) is arrested. In another embodiment, Fig. 4, a slit 215 is provided in a plate 216 mounted on a plate 204 carrying photo-cells, 212, 213 which scan axis 202 between points 217, 218. The scanning is terminated upon de-energization of motor 206 when the reflected light from source 200 passes through slit 215 on to the area 214 between the photo-cells 212, 213. A photovoltaic cell (235), Fig. 5 (not shown), energizes a movable coil (230) which rotates a needle (241) when the cell receives light through slit 236. The needle (241) engages the stepped surface of a plate (244) movable upwards by a lever 251. The needle (241) co-operates with a distance scale (245). The range finder may be used to adjust the projection lens of a projector as a function of the distance to the screen.