Patent GB-537253-A (GB)
Title: Apparatus for photographically recording the order of passage of moving objects
IPC: G03B15/00
Filed: 1939-08-14
Abstract: 537,253. Photographic cameras. DEL RICCIO, L. Aug. 14, 1939, No. 23452. Convention date, March 20. [Classes 97 (i) and 98 (i)] A camera for photographically recording the order of passage of moving objects across a reference line comprises a lens, means for supporting a travelling sensitized strip in the focal plane, and an exposure slit disposed transversely of the line of travel of the strip with one edge of the slit intersecting the optical axis of the lens. In use, the camera is positioned so that the image of the reference line coincides with this edge of the slit. The photographing of each object therefore commences at the moment it reaches the reference line, and owing to the movement of the film the objects appear on the photograph in the order of their arrival at the reference line. The camera shown is designed for simultaneously recording on two films 19, 22, of which the latter may be a paper strip, the films being used for judging the result of a race and for projection to be viewed by spectators. Two lenses 3, 4 in the same vertical plane are provided, the lens 3 being for recording the passage of the contestants past the finish line of a race, and the lens 4 for photographing a target or indicating device which is set up on an extension of the finish line to indicate that the camera has been properly positioned in relation to this line. The image beam from the lens 3 passes through a tube 18 containing beamsplitting prisms 23, 24 which divert part of it through a branch tube 20, images being produced at the gate apertures 17, 21 past which the films 19, 22 respectively are continuously moved. The apertures 17, 21, Fig. 8, are narrow slits, one edge being formed by a fixed plate 25 and being arranged on the optical axis of the lens 3 and the other being formed by a plate 27 pivoted on a slidable plate 26. By adjusting the plate 26 the slit is adjusted to as narrow a width as will give a sufficient exposure to the film, which is fed at approximately the speed of the moving images. The pivoted plate 27 is adjusted so that the width of the field of view included at both ends of the starting line is the same, the slot tapering towards the end at which the image of the far end of the line is formed. The field of view is thus confined to a narrow band of uniform width extending axially of the lens and having one face coincident with the finish line, and the resultant photograph, Fig. 12, shows the competitors in the order in which they arrived at this line. A scale of time is simultaneously photographed on the film by means comprising a disc 48 rotated by a synchronous electric clock movement and carrying on its lower face time indications and on its upper face corresponding contacts which cause a neon lamp 51 to illuminate each indication as it passes a lens 53 by means of which, a prism 55, and the beam splitting prisms 23, 24 the image is thrown on to the two films. A line 105, to which a vertical may be drawn to determine accurately which competitor first crossed the finish line, is formed on the film by a strip 104 bridging the slit 17. To record on the films that the camera has been correctly positioned, with the image of the finish line coincident with the vertical edge of the slit 17, a sliding plate shutter 8 is operated by an electric solenoid 15 before and immediately after the photographing of the competitors, to obscure the lens 3 and open the lens 4. An image of an indicating device in line with the finish line and at the opposite end of it to'that at which the camera is situated is then projected by the lens 4, by way of a light tube 29 having two right-angle bends and containing reflecting and beam-splitting prisms, to gate apertures 31, 28 behind which the films 19, 22 respectively pass. The film feeding sprockets are driven from a motor 70<SP>1</SP>, the sprockets 67 which move the films past the gate apertures 28, 31 being driven through a Geneva movement 75 to move the film a frame at a time, and the remainder being constantly driven.