| 摘要 |
PURPOSE: To provide a magnetic focusing device wherein magnetic drag, coupling between a static coil and a dynamic coil, and electrical/magnetic losses are small. CONSTITUTION: A magnetic focusing device, being disposed around a neck of a cathode-ray tube, is composed of members 20, 21 having different magnetic permeability and equipped with a magnetic frame having a gap 13 in a part radially nearest to the neck. A static focusing coil 11 is housed in the frame and energized by a direct current, while a dynamic focusing coil 12 is energized by a periodically changing current and disposed between the static focusing coil 12 and the neck. The dynamic coil is disposed near the gap part and uses, as a magnetic circuit, the frame part comprizing a material having magnetic permeability whose imaginary component is the smallest. |
