PURPOSE: To reduce the power burden of a convergence coil or the driving circuit of this coil by providing a linearity control means at one of the polariz ing units of respective projecting tubes at three projecting tubes for projecting pictures in three primary colors.
CONSTITUTION: Since the inductances of linearity correction coils 10-12 are different when a DC superimposing current is '0', a raster size on the tube surface of the projecting tube is different as well. Then, the raster size is made equal by providing a size coil 18 between a horizontal deflecting coil 8 and a linearity correcting coil 11 at a projecting tube 106. Then, a deflecting coil 109 arranged at the center is set to L1>L2 larger than other deflecting coils 108 and 110. Therefore, the electric correction amount of convergence coils 111-113, namely, the power of vertical convergence in red, green and blue can be decreased. Since the horizontal size is enlarged even when the vertical size can be optimized at that time, the coil 18 is provided for reducing the horizontal size.
KITAMURA MAKOTO
TANAKA TAKAMASA
HITACHI VIDEO & INF SYST