公开(公告)号：US3612756A

公开(公告)日：1971-10-12

申请号：US3612756D

申请日：1969-04-24

申请人： HITACHI LTD

发明人： AKATSU MITSUHARU ,  YONEYAMA TAKAO ,  IWASAKI TADAHIKO

IPC分类号： H04N5/14 ,  H04N9/28

CPC分类号： H04N5/141

摘要： A beam current limiting circuit for a cathode-ray tube (CRT) having at least a cathode, a grid and an anode comprising an anode circuit having a fly back transformer including a primary coil and a secondary coil, a power source, a high voltage rectifier for rectifying flyback pulses generated across the secondary coil, a beam current responsive means inserted between the power source and the secondary coil, a grid bias means, and switching means. The beam current responsive means is connected to the switching means and generates a control voltage whose value is so determined to be lower than the grid bias voltage while the beam current is larger than a predetermined value. The switching means is responsive to the control voltage and changes its conductive or nonconductive condition to supply the control voltage to the grid when the beam current exceeds the predetermined value, so that the beam current is prevented from exceeding the predetermined value.