GB462877A - Television transmitters and receivers - Google Patents

Abstract

462,877. Television. STANDARD TELEPHONES & CABLES, Ltd. May 29, 1936, No. 15229. Convention date, June 8, 1935. [Classes 39 (i), 40 (iii), and 40 (v)] All the points of an image, or portion of an image, are transmitted simultaneously by using a piezo-electric element of different frequency for each point. Received signals are impressed on a piezo-electric plate 1<1>, which is divided into elements having different frequencies and is so situated between two polarizing sheets 18, 19 that light from a source 21 is modulated in accordance with the vibration of the elements. The sheets may support electrodes 2<1>, 31 on each face of the crystal, and the analyzing sheet 19 may be translucent to reproduce the image. At the transmitter, each element is maintained in continuous vibration and modulates light from a view IT, which falls on a photo-electric cell 11 to produce a current of double the frequency of the element and proportional in amplitude to the intensity of the point incident on the element. The crystalline elements are in one large block, which decreases uniformly in two directions, and the two faces are sectionally divided by two sets of saw cut, at right angles, Figs. 2 and 3 (not shown). The block has electrodes supported by grids which register with the saw cuts and are associated with a common thermionic oscillator 7 or amplifier 8. The elements may be divided in groups, each of which has separate electrodes and is connected to its amplifier through an electric band-pass network, which admits the band of frequencies allocated to the group. The Specification as open to inspection under Sect. 91 comprises also a piezo-electric crystal mounted in a vacuum and covered on a surface normal to the electric axis with a photo-electric layer. Such a crystal may be kept in continuous vibration by light interrupted at its natural frequency. Transparent electrodes may be avoided by using a metallic grid. Spaces in the frequency spectrum may be used for transmitting other signals. This subject-matter does not appear in the Specification as accepted.