| 摘要 |
PURPOSE:To prevent a color shifts automatically at any time by providing magnetic sensors which detect variation of a magnetic field in three-axial directions X, Y, and Z, correcting sense amplifiers which amplify their detection signals into a constant output, and magnetic field correcting coils which cancel the magnetic field variation by the output of the amplifier. CONSTITUTION:Correcting sense amplifiers 9, 10, and 11 are corrected by variable resistances 12, 13, and 14 for respective magnetostatic fields. When an external magnetic field varies, the X-directional component, for example, is applied to the amplifier 9 as voltage variation through a magnetic sensor 1. The amplifier 9 amplifies its power by a multiple set by a variable resistor 15 for gain adjustment to supply a current to a magnetic field correcting coil 4. Its correcting current value is set to such a value that variation of the X component of the external magnetic field cancels variation of the X-directional component of the electron beam of a CRT. Therefore, said variation is the magnetic field of a correcting coil which returns the electron beam of the CRT to its original position, so there is no color shift caused.
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