Patent GB-1170007-A (GB)
Title: Apparatus for Displaying and Printing Information
Inventor: BREWSTER ARTHUR EDWARD
IPC: H04N1/27
Filed: 1968-01-25
Abstract: 1,170,007. Copying by scanning. STANDARD TELEPHONES & CABLES Ltd. 25 Jan., 1968, No. 3894/68. Heading H4F. In a facsimile system, Fig. 1A, an image, which may be illuminated by an infra-red source, is scanned line by line by a rotating mirror drum 13 having n-faces each inclined at 45 degrees to the axis of rotation, there being relative movement between the apparatus and the image, and the reflected radiation is directed via parabolic mirror 19 and mirror 20 on to phototube 21, the output of which is amplified 22 and fed to a variable frequency square wave generator 23. The output of generator 23 which comprises a series of constant amplitude square wave pulses which vary in frequency by an amount depending on the intensity of beam 24 is applied to the recording head assembly 16 via a rotary switch 31. Motor 14 which drives mirror drum 13 also drives the recording lead assembly via bevel gears 15. The number of recording heads 25 is equal to the number of faces on the mirror drum 13, and each head is mounted at the end of a rotating arm 26 and arranged to line scan a moving loop of recording medium 1 in synchronism with the scanning of the image. In the embodiment described, the recording heads comprise magnetic recording heads, Figs. 1B, 2A and 2B (not shown) although they may comprise electrostatic recording heads. For magnetic recording heads, recording medium 1 comprises a magnetic tape which is shaped in the form of an arc by guide member 28 in the vicinity of the recording head assembly. The magnetic tape is thus formed with a magnetic pattern representative of the scanned image, and this pattern is made visible by applying magnetic powder to the tape from dispenser 5. The tape may be viewed in a mirror 6 but since this mirror inverts the displayed image the magnetic pattern laid down by the recording heads must be initially inverted. Tape loop 1 completes its circuit by passing through a printing station 9 and via demagnetizing head 3a and cleansing stage 7 back to-the recording head assembly 16. The magnetic powder may comprise a ferrite powder and the individual grains are coated with a thermal fixing agent to permit thermal fixing of a printed copy in printing station 9 by transferring the ferrite powder to a paper web 10 by means of a pressure roll 9a and then heating the paper roll either by means of a heating device or by means of infra-red radiation. In a second embodiment, Fig. 3 (not shown), the magnetic tape is viewed directly and the magnetic powder pattern is transferred to a transfer roller (36) from where it is transferred to the paper web. To ensure that the powder adheres to the transfer roller the transfer roller is either recorded with a continuous mosaic of magnetic dots on a surface coating of magnetic material or it is made tacky with a thin coating of grease or adhesive. Instead of only one photo-tube 21, a linear array of photo-tubes (and recording head assemblies) may be used so that a plurality of contiguous lines of the image are swept out simultaneously by each face of the mirror drum. The output of the photo-tube may be applied directly to the recording head assembly, in which case dispenser 5 includes powder particles of various sizes.