Patent GB-1199291-A (GB)
Title: Opto-Electronic Picture Storage Apparatus
IPC: H04N1/36
Filed: 1967-09-13
Abstract: 1,199,291. Picture storage system. FRANZ MORAT G.m.b.H. 13 Sept., 1967 [13 Sept., 1966], No. 41746/67. Heading H4F. The Specification broadly relates to a picture storage system of the type comprising a T.V. display tube 5, Fig. 1, viewed by a camera tube 1 and fed with the output of the camera tube via amplifiers. A picture 15, which may be introduced to the above closed loop system electronically or as shown, by means of projection on to the camera tube via a semisilvered mirror 11, will thus be stored as a permanently displayed picture on tube 5. Such a storage system is described as used in the transference of the displayed picture on to a photographic film 15, Fig. 7, which film may form the programme for an automatic knitting machine for the production of knitted material carrying said picture. The displayed picture is in a raster form of 456 lines. Each line is divided electronically into 420 elements (picture raster generator 25, Fig. 7a, produces 420 pulses per line at output A). Twelve consecutive lines are recorded at a time on the film using twelve corresponding pairs of tracks 301/302, 303/304 . . . 323/324-one track of a pair recording the black information and the other track recording the white information. Film 15 is moved under a transverse array of modulated light sources 64, such that the lateral track on the film being exposed corresponds ú0 the column of elements being recorded in the twelve picture lines. One element is recorded per picture scan, the duration of the film in one position being such that the same element is recorded twice in consecutive scans. Thus, if the 154th column of elements of lines 1 to 12 is being recorded then the following table may be drawn up The film therefore advances 420 steps before all twelve lines are recorded. The knitting machine envisaged has four banks of needles such that each twelve line group has to be recorded four times. Thus 1,680 steps of the film are necessary before recording of the next twelve lines starts and 63,840 steps are required to record the entire picture. The video signal D from the camera tube is applied to the light sources 64 via AND gates 301-324. The picture scan sequential switch from one line to the next is controlled by 1 to 12 ring counter 29, and the gating through of the same element in consecutive lines is controlled by 1 to 420 ring counters and comparison circuit 19/21. The four times recording of each group of twelve lines is controlled by 1 to 4 ring counter 41 and the switch from one twelve line group to the next is controlled by 1 to 38 ring counters and comparison circuit 35/37. Assuming the step of the scanning of the 154th column of elements of lines 1 to 12 stepping motor 17 sets ring counter 19 to 154. The output A from generator 25 advances ring counter 21 and when count 154 is reached the comparison circuit, between the counters, emits a pulse which sets ring counter 29 to 1. This feeds an enabling pulse to gates 301/302. The other enabling input to gates 301/302 is fed by a comparison circuit between ring counters 35 and 37. Counter 37 is initially set to 1, since it is the first group of twelve lines which are to be recorded and counter 35 advances one count per revolution (one line group) of counter 29. Thus said coincidence circuit produces said enabling output only during the scanning of the lines 1 to 12. The subsequent operation of the system may be summarized by the following table: All above repeated another three times with counter 41 advancing to 4 thus advancing counter 37 whereby second group of lines are recorded. For the closed loop storage sytem of the invention to work, the rasters of the display tube and the camera tube must be in exact alignment. Photodetector means F, Figs. 2a and 5, are thus provided on the edge of the display tube to monitor the position of the scan and correction signals are fed to auxiliary deflection coils. The photo-resistor detectors F are housed in boxes 49 and 51 having slit apertures 55/53. The raster is extended at its edges to give blocks of lines 45 and 47. For correct positions of the raster in the horizontal direction the raster is only just visible through the aperture to the detector (5b, Fig. 5) whilst in the incorrect case 5a, a substantial amount of the raster is visible. The detectors will only detect misposition of the raster at the edge whereas correction is necessary to the raster when it is within the picture area. Thus any error voltages produced with the raster at the top and bottom edges of the picture, are stored in respective capacitors coupled by resistive potential dividers and gated through via switched transistor gates to the correction coil when the raster spot is in its corresponding position within the picture area. The picture area is divided up into sixteen columns-each having a photo-resistor detector F30, F31 &c. (top edge) and F30a, F31a &c. (bottom edge)- and four horizontal rows. An area defined by a column n and a row m is defined with reference to the elements used therefore in Fig. 3 by the suffix 3 mn. Gating signals h to z, Fig. 3a produced by generator 25, Fig. 7a are fed in various combinations to AND gates KV1 &c. and KH1 and the outputs of the particular pairs of enabled gates (one vertical KV, and one horizontal KH) are fed via respective ones of lines H and V to enable the gating transistors V3mn and H3mn at the point in the gating matrix corresponding to the position of the raster spot in the picture area. Thus, when the raster spot illuminates the photo resistor F32, signals i, k, n, p are such (thickened lines in Fig. 3a) that gate KV3 is enabled, thus enabling transistors V32, H32 and T32, whereby the potential generated across F32 is stored on capacitor C32. A similar " bottom error" voltage is stored on capacitor C32a coupled to capacitor C32 by resistor ladder R321, R322, R323, R324. Assuming a linearly varying error across the raster, the desired correcton voltage will appear at points A321, A322, A323 and A324. These voltages are gated through respective transistors H321, V321 &c. by the outputs on the lines H and V as required to the correction signal amplifier valve 58. A similar circuit is in use in the camera tube except that the photo-resistors are dispensed with and the video output of the camera tube used instead.