| 摘要 |
Horizontal scanning rate correction apparatus is provided for beam index color cathode-ray tubes of the type having a screen, an electron gun for projecting an electron beam upon the screen, a plurality of index elements positioned to be struck by the electron beam as it scans across the screen, a deflection device for causing the electron beam to repeatedly scan across the screen in a vertical succession of horizontal lines, and an index signal processing circuit for producing an index signal having a frequency determined by the frequency of the incidence of the electron beam upon the index elements as it scans horizontal lines and for controlling color switching circuitry which determines which of a plurality of color signals modulates the intensity of the electron beam. The horizontal scanning rate correction apparatus includes a memory circuit for storing correction values derived from the index signal processing circuit during horizontal scanning by the electron beam and representing the deviation of the horizontal scanning rate from a desired scanning rate at each of a plurality of horizontal sampling positions along a horizontal line. The apparatus further includes circuitry for reading the correction values from the memory circuit and for producing a corresponding signal which is supplied to the electron beam deflection device to substantially cancel deviations in the horizontal scanning rate. |
