Improvements in or relating to television cameras

• Main Authors: GERMANY LESLIE WALTER, WHITING KENNETH WALLACE
• Format: Patent
• Language: English
• Published: 29.11.1961
• Subjects: ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; PICTORIAL COMMUNICATION, e.g. TELEVISION

883,208. Television. PYE Ltd. Aug. 18, 1959 [Aug. 25, 1958], No. 27226/58. Class 40(3). An arrangement for determining the beam alignment of a magnetically focussed television pick-up tube 1 without an image section, said tube having a focussing coil 6 and an alignment coil 8, comprises the combination of said tube, means for producing a square waveform at a recurrence frequency less than the repetition frequency employed for frame deflection of the tube and means for applying the waveform to the focussing coil or the alignment coil so that it is superimposed in the current in the coil. The tube views an image 3, preferably a circle, and its output is applied through an amplifier 4 to a monitor 5. The square waveform has the effect of modifying the line and frame scanning amplitudes of the tube as well as rotating the image whereby there is produced on the monitor two superimposed images, i.e. circles, of different sizes. The direct current through the alignment coils is adjusted so that the circles become concentric. The square waveform is preferably at a sub-multiple of frame frequency. Details of circuit 7 for supplying a stabilised but adjustable current in which may be imposed a square waveform are described with reference to Figs. 2 and 3 (not shown).