The video display system which has automatic passive tube bias reactivity screen grid power source

摘要

(57) Abstract The video signal which it should display, through the video driver amplifier (50), is supplied to the cathode (32,34,36) of the picture tube (30). The beam current sensor (56) which is jointed to the cathode (32,34,36) in the same way gives the beam current status signal (S6). The AKB generator regulator (60) which responds to the beam current status signal (S6) supplies the black level amendment signal (Ia) to the driver amplifier (50) which adjusts the black level of the image which is displayed by the picture tube (30). The screen grid power-supply unit (70,90) in order to control the G2 (screen grid) voltage of the picture tube (30), as a specified function of the black level amendment signal (Ia) is provided, gives black level adjustment because of this, with the both of the AKB generator regulator (60) and also the driver amplifier (50) and the screen grid, (G2) all the black level control ranges forms the duplex feedback looping which largest it converts or expands, or. Therefore, in order usually, to configurate screen grid bias, the adjustment which is possible to remove the high tension screen control potentiometer (97) which is needed, completely according to need, or, at the time of applying that containment, to early adjustment follows is not necessary.