Title:
VIDEO DISPLAY DEVICE
Document Type and Number:
Japanese Patent JPH04229771
Kind Code:
A
Abstract:
PURPOSE: To provide a protection circuit which easily and effectively protects the image tube of a video signal device from spot burning during non-scanning periods. CONSTITUTION: The protection circuit is connected between an erase signal BBC source 80 and the grid of an image tube 30 and has a capacitor 65, which applies a negative grid cur-off bias to the image tube in accordance with the signal BBC and has a voltage divider 71/72 which supplies a positive bias voltage which is lower than the minimum output voltage of a video amplifier 20 to the grid of the image tube 30 at the time of the absence of the signal BBC. This voltage divider 71/72 is additionally provided with a voltage drop device 75, and the maximum bias voltage given to the grid of the image tube 30 is limited to a value, which is higher than the supply voltage of the voltage divider 71/72 and is lower than the maximum bias voltage of the video amplifier 20, for suppressing an excessive beam current.
Inventors:
TOOMASU DEIBITSUDO GAARII
RIROI SAMIYUERU UIGUNOTSUTO
RIROI SAMIYUERU UIGUNOTSUTO
Application Number:
JP12534591A
Publication Date:
August 19, 1992
Filing Date:
April 26, 1991
Export Citation:
Assignee:
THOMSON CONSUMER ELECTRONICS
International Classes:
H04N3/20; H04N9/64; (IPC1-7): H04N3/20
Domestic Patent References:
| JPS5744271A | 1982-03-12 |
Attorney, Agent or Firm:
Hiroshi Tanaka (2 outside)