Matsushita Electric Industrial Co., Ltd.

Yuji Amano

Yoshio Nirasawa

Norihide Kinugasa

Hideo Hamaguchi

An influence of a switching noise caused by a horizontal shift clock to an oscillation frequency of a voltage controlled oscillator should be eliminated, to prevent an image shift in a PAL skip period. For this purpose, an odd number line horizontal shift clock from an odd number line horizontal shift clock generator and an even number line horizontal shift clock from an even number line horizontal shift clock generator are switched by a horizontal shift clock switching circuit, to be input to a color LCD panel. The horizontal shift clock switching circuit selects and outputs either the odd number line horizontal shift clock or the even number line horizontal shift clock according to a line identifying signal, in a normal period. By contrast, in a PAL skip period a selecting state of the shift clock is inverted immediately upon start of a PAL skip period, from a selecting state right before the start of the skip period, and the selecting state is again inverted in half a cycle of a horizontal scanning period.

Horizontal shift clock pulse selecting circuit for driving a color LCD panel

An output circuit may include a power supply terminal, a ground terminal, and an output terminal connected to a capacitive load. Depending on the state of a load control input signal, the output circuit performs selectively a charging-current supplying operation of supplying a charging-current from the power supply terminal to the capacitive load and a discharging-current withdrawing operation of withdrawing a discharging-current from the capacitive load to the ground terminal. An overcharging-current prevention switch is provided to detect a short circuit between the output terminal and the ground terminal so as to stop or suppress the charging-current supplying operation. An overdischarging-current prevention switch is provided to detect a short circuit between the output terminal and the power supply terminal so as to stop or suppress the discharging-current withdrawing operation.

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Takatsuki, Japan

Yuji Amano