Precharge controlling method and display device using the same

A precharge controlling method, comprising the steps of:

• providing a voltage generating circuit with (a) an output circuit for outputting a voltage having a necessary level, and (b) a comparator;
• comparing an output voltage from said output circuit with another voltage using said comparator during a precharge time period, and feeding back an output signal from said comparator to said output circuit;
• and
• controlling a precharge voltage until the voltage having the necessary level output from said output circuit is reached,
• wherein,
• the output voltage from said output circuit is fed back to an input side of said output circuit through a feedback path,
• said output circuit is configured in a form of a source follower circuit composed of a drive transistor and a constant current source,
• a diode-connected transistor constitutes said feedback path,
• a current mirror circuit is provided, so that a current flowing through said diode-connected transistor is controlled so as to be equalized to a current flowing through said drive transistor, and
• the current mirror circuit includes switching elements, provided in respective current paths, that are controlled in accordance with the output signal from said comparator.

A display device, comprising:

• pixel portions disposed so as to correspond to intersection portions in which scanning lines and signal lines intersect with each other, respectively, each of said pixel portions comprising a switching element, a pixel cell, and a coupling capacitor;
• and
• a voltage generating circuit for supplying a coupling voltage to each of said coupling capacitors,
• wherein,
• said voltage generating circuit includes (a) an output circuit for outputting the coupling voltage, and (b) a comparator,
• during a precharge time period, said comparator compares an output voltage from said output circuit with another voltage, and an output signal from said comparator is fed back to said output circuit,
• a precharge voltage is controlled until the coupling voltage output from said output circuit is reached,
• said output circuit is configured in a form of a source follower circuit composed of a drive transistor and a constant current source, and
• a switching element connected between an output terminal of said output circuit and said constant current source is controlled in accordance with the output signal from said comparator.

A display device, comprising:

• pixel portions disposed so as to correspond to intersection portions in which scanning lines and signal lines intersect with each other, respectively, each of said pixel portions comprising a switching element, a pixel cell, and a coupling capacitor;
• and
• a voltage generating circuit for supplying a coupling voltage to each of said coupling capacitors,
• wherein,
• said voltage generating circuit includes (a) an output circuit for outputting the coupling voltage, and (b) a comparator,
• during a precharge time period, said comparator compares an output voltage from said output circuit with another voltage, and an output signal from said comparator is fed back to said output circuit,
• a precharge voltage is controlled until the coupling voltage output from said output circuit is reached,
• the output voltage from said output circuit is fed back to an input side of said output circuit through a feedback path,
• said output circuit is configured in a form of a source follower circuit composed of a drive transistor and a constant current source,
• the feedback path having a diode-connected transistor is connected between an output terminal and an input terminal of said output circuit,
• a current mirror circuit is provided for equalizing a current flowing through said diode-connected transistor to a current flowing through said drive transistor, and
• the current mirror circuit includes switching elements, provided in respective current paths, that are controlled in accordance with the output signal from said comparator.