Signal amplifier, signal amplifier circuit, signal line drive circuit and image display device

A signal amplifier circuit comprising:

• a buffer amplifier having an input terminal and an output terminal;
• a first signal output circuit for applying a first signal to the input terminal of said buffer amplifier during a detection period;
• a memory for storing a compensating signal generated at the output terminal by said buffer amplifier during the detection period,
• wherein during an operation period after the detection period, the compensating signal stored in said memory is combined with an input signal before said input signal is input to the input terminal of said buffer amplifier so that when said input signal is processed by said buffer amplifier during the operation period, the compensating signal cancels an offset characteristic of said buffer amplifier.

A signal amplifier, comprising:

• an operational amplifier;
• and
• a first gain setting condenser and a second gain setting condenser for setting a gain of said operational amplifier,
• wherein said first gain setting condenser is connected across an inverting input terminal and an output terminal of said operational amplifier,
• said second gain setting condenser is connected across the inverting input terminal and a constant voltage source, and
• an output signal obtained by noninverted amplification of a signal coupled to a noninverting input terminal of said operational amplifier is output from the output terminal.

A signal amplifier, comprising:

• an operational amplifier;
• and
• a first gain setting condenser and a second gain setting condenser for setting a gain of said operational amplifier, wherein:
• said first gain setting condenser is connected across an inverting input terminal and an output terminal of said operational amplifier,
• a noninverting input terminal of said operational amplifier is connected to a constant voltage source, and
• an output signal obtained by inverted amplification of a signal coupled to the inverting input terminal from a signal source through said second gain setting condenser is output from the output terminal.

A signal amplifier circuit, comprising:

• an amplifier;
• an input means for inputting a reference voltage to said amplifier during a detection period;
• and
• an adjusting circuit detecting a difference in voltage as an offset voltage between the reference voltage and an output voltage from said amplifier during the detection period, and during an operation period after the detection period, shifting a level of the input signal before the input signal is provided to said amplifier by a level of the offset voltage to reduce the offset voltage of said amplifier,
• wherein a gain of said amplifier is set to an amplitude ratio of the shifted input signal to the compensating signal.

A signal line drive circuit, comprising:

• a sampling circuit sampling a video signal synchronously with a clock signal;
• and
• an output device sending video signals obtained by sampling over a data signal line at one time in synchronous with another clock signal,
• wherein said output means includes:
• an operational amplifier;
• and
• a first gain setting condenser and a second gain setting condenser for setting a gain of said operational amplifier,
• said first gain setting condenser is connected across an inverting input terminal and an output terminal of said operational amplifier,
• said second gain setting condenser is connected across the inverting input terminal of said operational amplifier and a constant voltage source and sends an output signal obtained by noninverted amplification of a video signal coupled to a noninverting input terminal of said operational amplifier over the data signal line.

A signal line drive circuit, comprising:

• a sampling device sampling a video signal synchronously with a clock signal;
• and
• an output device providing sampled video signals over a data signal line at one time synchronously with another clock signal,
• wherein said output device includes:
• an operation amplifier;
• and
• a first gain setting condenser and a second gain setting condenser for setting a gain of said operational amplifier,
• said first gain setting condenser is connected across an inverting input terminal and an output terminal of said operational amplifier,
• a noninverting input terminal of said operational amplifier is coupled to a constant voltage source and provides an output signal obtained by inverted amplification of a video signal coupled to the inverting input terminal from a signal source through said second gain setting condenser over the data signal line.

A signal line drive circuit, comprising:

• a sampling device sampling a video signal synchronously with a clock signal;
• and
• an output device providing sampled video signals over a data signal line at one time synchronously with another clock signal,
• wherein said output device includes:
• an amplifier;
• an input means for inputting a reference voltage to said amplifier during a detection period;
• and
• an adjusting circuit detecting a difference in voltage as an offset voltage between the reference voltage and an output voltage from said amplifier during the detection period, and during an operation period after the detection period, shifting a level of a video signal before the video signal is input to the amplifier by a level of the offset voltage to reduce the offset voltage of said amplifier, and
• wherein a gain of said amplifier is set to an amplitude ratio of the shifted video signal to the compensating signal.