Solid-state image sensor having a voltage applier and signal readout method thereof

A signal readout method of a solid-state image sensor comprising:

• generating a signal electric charge using a photoelectric converter,
• wherein the signal electric charge corresponds to an intensity of incident light;
• holding a potential of the signal electric charge using the photoelectric converter;
• providing an amplifier unit including a first MOS transistor, the first MOS transistor having a gate terminal configured to read out a held potential by the photoelectric converter, a drain terminal that serves as an output terminal, and a source terminal;
• generating a binary signal using a signal converter,
• wherein the binary signal corresponds to the intensity of incident light based on an output of the first MOS transistor;
• and
• applying a ramp waveform voltage to the source terminal of the first MOS transistor, while the held potential, which is to be read out, corresponding to the intensity of incident light, is held in the photoelectric converter,
• wherein the ramp waveform voltage is applied using a voltage applier,
• the binary signal has a pulse width that corresponds to the held potential, and is generated by the signal converter based on a change of the output of the first MOS transistor accompanying a change of the ramp waveform voltage.

A solid-state image sensor comprising:

• a photoelectric converter for generating a signal electric charge and for holding a potential of the signal electric charge,
• wherein the signal electric charge corresponds to an intensity of incident light;
• an amplifier unit including:
• a first MOS transistor having a gate terminal connected to an output terminal of the photoelectric converter, the gate terminal configured to read out a held potential by the photoelectric converter, a drain terminal that serves as an output terminal, and a source terminal;
• a voltage applier for applying a ramp waveform voltage to the source terminal of the first MOS transistor or to the output terminal of the photoelectric converter via a capacitative element;
• a second MOS transistor having a gate terminal, the second MOS transistor being connected between an output signal line and a power supply line,
• wherein the output signal line provides an output signal of the amplifier unit;
• a charge controller for charging a stray capacitance, having one end that is connected to the signal line by providing electrical conduction of the second MOS transistor before the ramp waveform voltage is applied,
• wherein the charge controller is a circuit for applying a control voltage to the gate terminal of the second MOS transistor;
• and
• a signal converter for generating a binary signal having a pulse width corresponding to the held potential based on a voltage of the output signal line, the voltage being changed by discharging a charged electric charge of the stray capacitance via the first MOS transistor, when the ramp waveform voltage is applied to the source terminal of the first MOS transistor or to the output terminal of the photoelectric converter via the capacitative element by the voltage applier, while a potential to be read out is held in the photoelectric converter.

A signal readout method of a solid-state image sensor comprising:

• generating a signal electric charge using a photoelectric converter,
• wherein the signal electric charge corresponds to an intensity of incident light;
• holding a potential of the signal electric charge using the photoelectric converter;
• providing an amplifier unit including a first MOS transistor having a gate terminal connected to an output terminal of the photoelectric converter, the gate terminal configured to read out a held potential by the photoelectric converter, a drain terminal that serves as an output terminal, and a source terminal;
• connecting a second MOS transistor between an output signal line and a power supply line, the second MOS transistor having a gate terminal;
• wherein the output signal line provides an output signal of the amplifier unit;
• generating a binary signal using a signal converter,
• wherein the binary signal has a pulse width corresponding to the held potential based on a voltage on the output signal line,
• a stray capacitance has one end is connected to the signal line, and is charged by applying a predetermined control voltage to the gate terminal of the second MOS transistor to provide electrical conduction of the second MOS transistor before the ramp waveform voltage is applied by the voltage applier, and while a potential to be read out, which corresponds to an intensity of the incident light, is held in the photoelectric converter, and
• the binary signal has a pulse width corresponding to the held potential, and is generated by the signal converter based on the voltage on the signal line, the voltage being changed by discharging a charged electric charge of the stray capacitance via the first MOS transistor in a changing process of the ramp waveform voltage;
• and
• applying the ramp waveform voltage to the source terminal of the first MOS transistor or to the output terminal of the photoelectric converter via the capacitative element, the ramp waveform voltage is applied using a voltage applier.