Kabushiki Kaisha Toshiba

Hidehiko Tachibana

Takanori Utsunomiya

Akihiro Sueda

Masayuki Kawasaki

Yasunori Kuwasima

Syuji Katsuki

Output circuits OC1-OC240 supplied with picture signals VIN to output drive signals are provided. Each of the output circuits OC includes a switching element SW1, a capacitor C1 and a switching element SW2 provided at a first path, and a switching element SW3, a capacitor C2 and a switching element SW4 provided at a second path connected in parallel with the first path, and includes a sample-hold circuit SH1 supplied with a picture signal and a hold switching signal of which level is switched at a first period to alternately store the picture signal into the capacitor C1 or the capacitor C2 in accordance with hold switching signal to output it, and an amplifier AMP1 supplied with an output of this circuit SH1 to amplify that output to output it as a drive signal. Further, buffers are provided every output circuits OC. These buffers are connected to each other in series. Hold switching signal inputted from the external is inputted to the buffers and are propagated therethrough. Thus, outputs from respective buffers are delivered to corresponding output circuits OC. By providing such configuration, in accordance with this invention, it is suppressed that rounding of waveform takes place by the influence of wiring resistor and/or parasitic capacitor for a time period during which hold switching signal is transferred through the signal line and feed-through current in carrying out switching operation is thus increased so that power consumption become large.

Liquid crystal drive circuit and liquid crystal display device

In a level shift circuit having a bias circuit and an output circuit, the current consumption of the bias circuit can be suppressed, and further the delay of the output signal relative to the input signal can be reduced. The ratio circuit comprises a bias circuit block (5) composed of a transistor (1) connected to a high potential power source (7) and having a gate to which an input bias INBIAS is applied through a bias input terminal (11), a transistor (2) connected in series to the transistor (1) so as to function as a resistance, and a transistor (13) connected in series to the transistor (2) and a low potential power source (8); and an output circuit block (6) composed of a transistor (3) connected to the high potential power source (7) and having a gate to which an input signal IN is applied through an input terminal (10) and a drain from which an output signal OUT is derived to an output terminal (12), and a transistor (4) connected in series to the transistor (3) and a low potential power source (8). Further, a voltage VBIAS1 is applied from the drain of the transistor (1) to the gate of the transistor (4), and further a switching signal is applied from the drain of the transistor (3) to the gate of the transistor (13).

High speed level shift circuit

A booster circuit device comprises: a liquid crystal drive circuit (14) whose dissipated current changes; a timing circuit (11) for outputting a select signal according to the dissipated current of the liquid crystal drive circuit; a drive signal select circuit (12) for selecting and outputting any one of at least two drive signals CLK of different frequencies on the basis of the select signal outputted by the timing circuit (11); and a booster circuit (13) for supplying a supply voltage to the liquid crystal drive circuit (14) on the basis of the drive signal CLK outputted by the drive signal select circuit (12). Since any of the drive signals CLK of different frequencies can be selected and applied to the booster circuit (13) according to the dissipated current of the liquid crystal drive circuit (14), it is possible to reduce the current dissipation of the booster circuit, that is the current dissipation of the whole booster circuit device can be reduced markedly.

Growing community of inventors

Yokohama, Japan

Hidehiko Tachibana