Patent GB-1005566-A (GB)
Title: Device for storing television images
IPC: H04N5/781
Filed: 1962-03-22
Abstract: 1,005,566. Television recording and reproducing systems. SIEMENS & HALSKE A.G. March 22, 1962 [March 23, 1961], No. 10951/62. Heading H4F. Television signals from a camera K corresponding to a single field in an X-ray viewing apparatus are recorded on a circular track on a plate-shaped magnetic recording device S 1  and are reproduced repeatedly on a monitor display Sg under the control of a ten-stage counting chain Z 1  which is stepped along by field synchronizing pulses separated from the camera signal by a stage A 1 . A second similar recording device S II  and associated counting chain Z II  is provided to permit the apparatus (1) to record and reproduce a complete frame formed of two successive interlaced fields and (2) to record and reproduce one field in every ten with successive recordings being made alternately on recording devices S I  and S II . The recording devices comprise erase heads L 1 , L 2  and record/reproduce heads AW I , AW II , the operations of which are changed over by relays R I  and R II . The recording devices make one revolution in the time of one field. Erase signals are obtained from a common oscillator L, the input signals are applied via amplifiers VA I , VA II  and the output signals are derived via amplifiers VC 1 , VC 11 . Control of the respective operations is effected by flip-flop circuits TA I , TA II , TB I , TB II , TC which are triggered by signals from the counting chains derived from the stages indicated. Pulsing of the X-ray source is controlled by circuit Xp and blanking of the camera (a vidicon) is controlled by circuit Sp, the circuit likewise being operated at the appropriate times by pulses from the counting stages as indicated. The signals for recording are applied to a frequency modulator M and the reproduced signals are demodulated in a stage D. The general sequence of operations is shown in Fig. 2. Operation is initiated by a start key ST (line 2) and starts at the immediately following field synchronizing pulse (lines 1 and 5). The counting chains then step 1-0 (lines 3 and 4) and control X-ray exposure (line 6), erase (lines 7 and 8), camera blanking (line 9), record/ reproduce change-over (lines 10 and 11) and record (lines 14 and 15). Reproduction is effected as at lines 16-21 depending on the mode of operation adopted which is selected by operation of switches U1-U5. In the case of a single field (mode b) only counting chain Z 1  is employed and the output is switched to amplifier VC 1  continuously when stage Is triggers (line 16). In the case of a complete frame-i.e. two successive fields-(mode c) the second chain Z II  is triggered from the second stage of chain Z I  soasto cause successivefieldstoberecorded, the first in S I  and the second in S II . The output is then switched back and forth between amplifiers VC I  and VC II  by field synchronizing pulses extracted from the reproduced signal by stage A 2  (lines 19-21). In the case of mode a the two counting chains are connected in a closed ring so as to operate continuously whereby one field in every ten is recorded alternately in S I  and S II . The output is switched back and forth between amplifiers VC I  and VC II  at intervals of ten fields (lines 17 and 18).