| 摘要 |
PROBLEM TO BE SOLVED: To enable a degaussing device to automatically perform manual degaussing when it is estimated that the color shift becomes significant even when the device is not instructed each time to perform manual degaussing. SOLUTION: Degaussing is performed by installing an automatic degaussing coil 12 and a manual degaussing coil 14 to a CRT 10 mounted on a moving body, for example, a ship. An automatic degaussing circuit 18 executes degaussing with a weak magnetic field by using the coil 12 synchronously with a synchronizing signal from a synchronization control circuit 16, namely, periodically. A manual degaussing circuit 20 executes degaussing with a strong magnetic field by using the coil 14 in accordance with a command from an operation part 22. A discriminating circuit 26 which discriminates the need for compulsory manual degaussing estimates the variation of geomagnetism after the coil 14 and circuit 20 perform degaussing from the current position of the ship and geomagnetic data and, when the estimated value exceeds the limit, causes the circuit 20 to execute degaussing with the strong magnetic field.
|
