GB952325A - Method and apparatus for checking the scanning linearity and geometry of television apparatus - Google Patents

Abstract

952,325. Television. PYE Ltd. July 22, 1960 [July 31, 1959], No. 26361/59. Heading H4F. The linearity and geometry of the scan of a television pickup tube or of a picture reproducing tube are checked by optically comparing a master pattern with an electronically produced grid pattern. The master pattern (Fig. 4) is formed as a slide and comprises rows of opaque markings M on a transparent background (or of transparent markings on an opaque background) and the inclination of each row to the horizontal is made approximately equal to. that of the scanning lines in the system to be tested. Additionally, the slide is provided with at least one mark to identify the particular scanning standard with which the slide is to be employed. For testing a picture reproducing tube such as a monitor tube 1 a grid pattern produced on the latter by means of a generator 2 is optically compared with the master pattern 5 and the scanning generator and/or the deflection means (e.g. deflection coils) adjusted to cause the grid pattern to be symmetrical with the master pattern. When testing a pickup tube, the latter, 6 (Fig. 3), is caused to generate a video signal by " viewing " the master pattern 5 and this signal is then displayed on a monitor tube 8 together with an electronically generated grid pattern from generator 9. The scanning means &c. of pick-up tube 6 are then adjusted as in the case of the picture reproducing tube test.