Patent GB-1040589-A (GB)
Title: Apparatus for recording television pictures cinematographically
Inventor: NEALE DENIS MANKTELOW
IPC: H04N5/84
Filed: 1963-11-21
Abstract: 1,040,589. Recording television pictures cinematographically. ILFORD Ltd. Nov. 20, 1964 [Nov. 21, 1963], No. 46067/63. Heading H4F. To reduce the amount of film used in a cinematograph camera 10 when photographically recording television pictures from the screen of a television reproducer tube V 8  the frame advance rate of the camera, i.e. the number of television pictures recorded per second, is reduced below a maximum rate (half the television picture repetition rate) by means of control signals derived from the frequency content of the video signals when movement in a picture to be photographed is slow, i.e. when the change in the television picture content has a frequency below the picture repetition rate. The control signals which control the frame advance rate and thus the shutter of the camera 10 are derived from the composite video and blanking signal applied on line 4 by means of a low-pass filter 12, which attenuates frequencies in excess of the television picture repetition rate, i.e. 25 c/s., a phase-splitter V 1 , a Schmitt trigger V 2 , V 3 , R 3 -R 6 , a relay A 4  with relay contacts a/1-a/4 and a ring counter circuit V4-V7. In the normal or rest state of the circuit when there is no change in the television picture content, valve V 2  is non-conducting and valve V 3  conducts, energizing relay A 4  and thus holding relay contacts a/1-a/4 open. Frame repetition pulses, e.g. at 50 c/s., are applied to the ring counter along line 5 and in the rest state only cold-cathode gas-filled trigger tube V 7  conducts and thus a voltage is developed across resistor R 21  causing diode D 3 , which is connected to the cathode of tube V 8 , to conduct and suppressing the electron beam in tube V 8 , it being arranged that when diodes D 3  and D 4  are not conducting the cathode of tube V 8  is at such a potential that a negative reproduction of the television picture appears on the screen of tube V 8 . Although the frame repetition pulses are applied to all the trigger electrodes of tube V 4 -V 7 , it is arranged that the tubes only trigger when a positive bias voltage is simultaneously applied to the respective trigger electrode. Whenever a change in television picture content has a frequency of the order of the picture repetition rate there is a significant difference between successive frames of the television picture to produce a transient change in the voltage developed across input resistor R 9 . As a result either the anode or the cathode of valve V 1  undergoes a positive excursion so that either diode D 1  or diode D 2  conducts, charging the capacitor C 5  positively and operating the Schmitt trigger circuit which causes relay A4 to be de-energized momentarily closing contacts a/1-a/4. When contact a/4 closes the positive bias voltage of the cathode of tube V 7  is connected to the trigger electrode of tube V 4  through resistor R 14  and when the next frame repetition pulse appears on line 5 tube V 4  conducts simultaneously extinguishing the discharge in tube V 7 . Further diode D 4  conducts so that the electron beam in tube V 8  remains suppressed. The next frame repetition pulse triggers tube V 5  and extinguishes tube V 4  and so on until tube V 7  triggers at the end of the cycle, the cycle starting again when the Schmitt trigger circuit operates once more. When tube V 5  and V 6  conduct two consecutive frames of the television picture are displayed on the screen of tube V 8 , the electron beam in tube V 8  being suppressed when tubes V 7  or V 4  conduct. When tube V 7  conducts the positive voltage applied to line 8 causes a control solenoid (not shown) to close the shutter of camera 10 and advance the film by one frame. When the Schmitt trigger circuit operates the camera shutter is opened while tube V 4  conducts, two consecutive frames of the television picture are photographed by the camera 10 while tubes V 5  and V 6  conduct and the camera shutter is finally closed again and the film advanced by one frame when tube V 7  conducts once more. The circuit is such that successive television pictures are substantially identical only the first picture of such a series is recorded. A minimum rate, e.g. one picture every two seconds, may be imposed on the rate at which television pictures are recorded by closing the manual switch S 1  and adjusting resistor R 7 . Synchronization of the projected picture with the sound is achieved by recording on a separate track of the tape in a magnetic tape-recorder 14 an audio frequency, e.g. 1 kc./sec., at times corresponding to the times of camera frame advance, thus providing a record of the points in the accompanying sound recording at which successive frames of the television picture were photographed. To further reduce the amount of film used an anamorphotic lens 11 may be used to reduce the conventional 4 x 3 format of the television picture to a 4 x 1¢ format.