| 摘要 |
PURPOSE:To superimpose a teletext signal having a standard horizontal scanning frequency onto an internal video signal of the non-interlace system by providing a double speed converting means converting the horizontal scanning frequency of the teletext signal. CONSTITUTION:The interlace system television video signal having the standard horizontal scanning frequency is converted into the non-interlace system video signal having a horizontal scanning frequency of 31.5kHz by a processing section 14. On the other hand, teletext picture signals RO, GO, BO having the standard horizontal frequency given from a teletext receiver and a primary color video signal switch control signal YS and a luminance control signal YM are converted into signals DRO', DGO', DBO', YM', YS' having the horizontal scanning frequency of 31.5kHz by double speed converters 56-70. With the switching signal YS' and the luminance control signal YM' at logical 1, a 1/2 attenuator 16 applies attenuation processing to the internal video signals DRi'-DBi' and the switch 18 is switched to the teletext to apply superimposition.
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