Abstract: Control circuitry, in an AKB sample pulse generator, enables charging of a capacitor upon initiation of a vertical retrace pulse, initiates discharge of the capacitor in response to termination of the retrace pulse and concurrently produces an AKB output pulse having a width (W) determined by an RC time constant and having a delay time (Td) relative to initiation of the retrace pulse that is equal to the length (L) of the retrace pulse and that is independent of the value of the RC time constant. Advantageously, the AKB sample pulse delay time tracks variations, if any, of the retrace pulse and is unaffected by parameter variations of the RC components. Additionally, the sample pulse width can be controlled with analog simplicity and can be increased, for the same amount of overscan as compared with systems in which both pulse delay and width exhibit component sensitive delay times, thereby providing improved AKB control accuracy due to the increased "aperture" or sampling time.

Abstract: A receiver includes a kinescope, a driver amplifier and an integrated automatic kinescope bias (AKB) circuit. A soft start circuit includes a timing capacitor, external to the integrated circuit, and a control circuit within the integrated circuit which limits the AKB current adjustment range during turn-on to a time determined by the external capacitor. The capacitor is effectively isolated from the integrated circuit to prevent discharge thereof by protection diodes of the IC whereby the time constant of the overall AKB circuit is substantially the same for both hot start conditions and cold start conditions thereby avoiding undesirable visual start-up artifacts such as black level and contrast shifts during warm-up of the kinescope for either a cold start condition or a hot start condition.