Patent GB-195577-A (GB)
Title: Improvements in and relating to telautography or phototelegraphy
IPC: H04N1/41
Filed: 1921-09-19
Abstract: 195,577. Bartholomew, H. G., and McFarlane, M. L. D. Sept. 19, 1921. Copying - telegraphs. -In picture transmission to obtain gradation of tone in the reproduction, a plurality of representations from the original, each corresponding with a given fraction or range of tone, are transmitted, and the corresponding received representations are used to form a composite reproduction of the original. An intermediate record of the tone variations, such as a perforated tape, may be used, and such record may be effected by the method and means described in Specification 197,402. Alternatively, the record may be formed on wax, as in making talking-machine records. The necessary current variations for transmission may be by any means, such as making the representation in insulating material upon a conducting sheet adapted to be bent round the transmitter mandrel, or light variation may affect a selenium cell. Or the representations may be in relief or act upon a microphone. Control signals may be sent indicating that some definite portion of the original, such as a zone, has been transmitted. The transmission of tone variation may be effected telepbonically by sound, the variations controlling a scund-producer. Reproduction from the record may be by manual operation of an inking device, or may take place automatically, the photographic exposure of a sensitized surface being varied in duration or intensity, for example by means of the character indicated in Specification 166,917. The elementary areas composing adjacent zones of the picture may be in staggered relation. Figs. 1 and 2 show four representations 1, 1<a>, 1<b>, 1<c> corresponding with different ranges of tone, mounted on a cylinder adapted to be rotated and moved axially by a screw 4, the representa-. tions co-operating with corresponding transmitting styles or contacts 10, 10<a>, 10<b>, 10<c>. A toothed wheel 7, co-operating with a brush 9, is adapted to send a control signal for each elementary area of the picture, and these signals may control the feed of the reproducing apparatus. Means for producing an intermediate perforated tape record are described, identical with the means described in Specification 197,402. Fig. 10 shows a device for producing photographically a composite reproduction corresponding with five tone-range representations transmitted and forming a perforated tape representation similar to a five-unit code telegraph tape. Sources of light 100, - - - 100<d> give points of light registering with the rows of perforations in the tape, which is. moved over the table 109, the perforations serving to control the passage of light. The light passing through the perforations is concentrated on a single spot on a sensitized sheet 102 arranged round a cylinder 103 rotated and fed' axially at suitable speed, the depth of the composite tone produced depending on whether light is passing through one or more perforations in the tape. One Provisional Specification describes the employment of a half-tone representation in which the valves are represented by dots of different sizes, and the transmission by a commutator arrangement of groups of current impulses the number of impulses in a group depending upon the size of the corresponding dot, and another arrangement in which the dots control the duration of sounds produced by a buzzer and transmitted telephonically to produce a. record on wax by a recorder producing wavy or sinuous grooves, or by a sluggishly acting relay the armature of which operates a cutting point to produce non-sinuous grooves of different lengths.