GB276399A - Improvements in or relating to picture telegraphy and the like - Google Patents

Abstract

276,399. Wright, G. M., Smith, S. B., and Davis, N. E. April 21, 1926. Copying - telegraphs. - The form carrying the message or picture to be transmitted is explored by a moving optical system mounted coaxially within it, the arrangement being such as to project a spot of light from a stationary source on to successive elemental areas of the form and to collect the reflected light, varying in accordance with the light and shade Values of these areas, upon a stationary light-sensitive cell. Transmitting-arrangements.-A beam of light 1, Fig. 1, directed axially along a tube 2 is reflected at right-angles by a prism 3 and focused on the message form 6 by a lens 4 mounted in a tube 10. The form 6 is mounted on a glass, or other transparent cylinder 1 coaxial with the tube 2. The light reflected from the form is collected by a mirror 11, passes through a lens 8, and is reflected axially along the tube 2 by a mirror 9 for projection upon the light-sensitive cell. In a modification, the lens 8 is placed at one side of the lens 4. The tube 2, carrying with it the optical devices. is rotated about its axis and is advanced axially during the rotation. Alternatively, the axial movement mav be imparted to the form 6. The transparent cylinder 7 mav be replaced by one of brass or other metal provided with a transverse slot for passage of the light, the form 6 sliding across the slot longitudinally of the cylinder. An oscillatory instead of a rotary movement may be imparted to the optical system. Receiving-arrangements. In the receiver the intensity of the beam 1 incident on the prism 3 is modulated by a Kerr cell or like device subjected to the received currents, the form 6 is replaced by a photo-sensitive surface, and the lens 8 and mirror 9 are dispensed with. Any suitable synchronizing arrangement is employed and means are provided for rotating the carcase of the motor at the receiving station manually to bring the reproduction into correct position upon the photo-sensitive surface. Distributor systems. For multiplex transmission each picture occupies a different arc of the cylinder 7, successive pictures are displaced longitudinally of the cylinder, each picture is explored by an independent optical system, and such systems are actuated by common driving means.