Physical quantity distribution detecting apparatus and imaging apparatus

1. A physical quantity distribution detecting apparatus comprising:

a sensor array in which a plurality of unit sensors for sensing physical quantity are two-dimensionally arranged in a matrix, each unit sensor generating an analog signal; and

analog-to-digital conversion means that includes a plurality of comparators for comparing the analog signal read from the unit sensor with a reference signal, the analog-to-digital conversion means generating a digital signal by measuring a period of time or measuring a signal corresponding to the period of time of each comparison output of the plurality of comparators,

wherein,

each of the plurality of comparators includes a differential input unit that compares the corresponding analog signal with the reference signal and an inverted buffer unit that inverts the polarity of an output of the differential input unit,

each differential input unit is coupled to its corresponding inverted buffer unit by a signal line, and

each of the plurality of comparators includes at least one capacitor element connected between its signal line and a constant-voltage line, the constant voltage line being coupled to the differential input unit and the inverted buffer unit.

2. An imaging apparatus comprising:

a solid-state imaging device including a plurality of unit pixels that are two-dimensionally arranged in a matrix, the plurality of unit pixels each including a photoelectric transducer that converts incident light into an electric signal; and

an optical system that guides light emitted from a subject to an image-capturing plane of the solid-state imaging device,

wherein the solid-state imaging device includes analog-to-digital conversion means that includes a plurality of comparators for comparing an analog signal read from the unit pixel with a sloped reference signal, the analog-to-digital conversion means generating a digital signal by measuring a period of time or measuring a signal corresponding to the period of time of each comparison output of the plurality of comparators, and

wherein,

each of the plurality of comparators includes a differential input unit that compares the corresponding analog signal with the reference signal and an inverted buffer unit that inverts the polarity of an output of the differential input unit,

each differential input unit is coupled to a corresponding inverted buffer unit by a signal line, and

each of the plurality of comparators includes at least one capacitor element connected between the signal line and a constant-voltage line, the constant voltage line being coupled to the differential input unit and the inverted buffer unit.

3. A physical quantity distribution detecting apparatus comprising:

a sensor array in which a plurality of unit sensors for sensing physical quantity are two-dimensionally arranged in a matrix; and

an analog-to-digital conversion unit that includes a plurality of comparators for comparing an analog signal read from the unit sensor with a reference signal, the analog-to-digital conversion unit generating a digital signal by measuring a period of time or measuring a signal corresponding to the period of time of each comparison output of the plurality of comparators,

wherein,

each of the plurality of comparators includes a differential input unit that compares the corresponding analog signal with the reference signal and an inverted buffer unit that inverts the polarity of an output of the differential input unit,

each differential input unit is coupled to a corresponding inverted buffer unit by a signal line, and

each of the plurality of comparators includes at least one capacitor element connected between the signal line and a constant-voltage line, the constant voltage line being coupled to the differential input unit and the inverted buffer unit.

4. An imaging apparatus comprising:

a solid-state imaging device including a plurality of unit pixels that are two-dimensionally arranged in a matrix, the plurality of unit pixels each including a photoelectric transducer that converts incident light into an electric signal; and

an optical system that guides light emitted from a subject to an image-capturing plane of the solid-state imaging device,

wherein the solid-state imaging device includes an analog-to-digital conversion unit that includes a plurality of comparators for comparing an analog signal read from the unit pixel with a sloped reference signal, the analog-to-digital conversion unit generating a digital signal by measuring a period of time or measuring a signal corresponding to the period of time of each comparison output of the plurality of comparators, and

wherein,

each of the plurality of comparators includes a differential input unit that compares the corresponding analog signal with the reference signal and an inverted buffer unit that inverts the polarity of an output of the differential input unit,

each differential input unit is coupled to a corresponding inverted buffer unit by a signal line, and

each of the plurality of comparators includes at least one capacitor element connected between the signal line and a constant-voltage line, the constant voltage line being coupled to the differential input unit and the inverted buffer unit.

5. A physical quantity distribution detecting apparatus comprising:

a sensor array in which a plurality of unit sensors for sensing physical quantity are two-dimensionally arranged in a matrix; and

analog-to-digital conversion means that includes a plurality of comparators for comparing an analog signal read from the unit sensor with a reference signal, the analog-to-digital conversion means converting a digital signal by measuring a period of time or measuring a signal corresponding to the period of time of each comparison output of the plurality of comparators,

wherein:

each of the plurality of comparators includes at least one capacitor element connected between a signal line and a constant-voltage line;

each of the plurality of comparators includes a differential input unit that compares the corresponding analog signal with the reference signal and an inverted buffer unit that inverts the polarity of an output of the differential input unit;

one of the at least one capacitor element is connected to a signal line, which is connected to an output terminal of the differential input unit and an input terminal of the inverted buffer unit, and the constant-voltage line;

each of the plurality of comparators further includes at least two inverters that are cascaded with each other with respect to an output terminal of the inverted buffer unit; and

another one of the at least one capacitor element is connected between the signal line, which is provided between the at least two inverters, and the constant-voltage line.