Imaging apparatus and method of driving the same

摘要

An imaging apparatus and a method of driving the same that can generate a digital data of a high resolution pixel signal are provided. The imaging apparatus includes: a pixel (10-1) for generating a signal by photoelectric conversion; a comparing circuit (30-1) for comparing a signal based on the pixel with a time-dependent reference signal; a counter circuit (40-1) performing a counting operating until an inversion of a magnitude relation between the signal based on the pixel and the time-dependent reference signal; and a selecting circuit (30-2) for setting a time-dependent change rate of the reference signal, according to a signal level of the signal based on the pixel.

主权项

1. An imaging device comprising:
a photoelectric-conversion unit configured to generate a charge by photoelectric conversion; an analog-to-digital (AD) converter; and a bit-shifting unit, wherein the AD converter comprises a comparing circuit and a selecting circuit, and wherein: the comparing circuit compares a signal based on the charge with a predetermined threshold, to output a first comparison result signal indicating a result of the comparing the signal based on the charge with the predetermined threshold to the selecting circuit, and when the first comparison result signal indicates that the signal based on the charge is smaller than the predetermined threshold, the selecting circuit outputs, to the comparing circuit, a first ramp signal having a voltage changing at a first time-dependent change rate, and when the first comparison result signal indicates that the signal based on the charge is larger than the predetermined threshold, the selecting circuit outputs, to the comparing circuit, a second ramp signal having a voltage changing at a second time-dependent change rate larger than the first time-dependent change rate, the comparing circuit compares the signal based on the charge with the first or second ramp signal output from the selecting circuit based on the first comparison result signal, and outputs a second comparison result signal indicating a result of the comparing the signal based on the charge with the first or second ramp signal, and based on a timing of a transition of a signal level of the second comparison result signal, the AD converter generates a digital signal corresponding to the signal based on the charge, the AD converter outputs, to the bit-shifting unit, data based on the first comparison result signal and a digital signal based on the signal based on the charge, and based on the data, the bit-shifting unit operates to perform a bit-shifting operation according to a ratio between the first and second time-dependent change rates, to at least one of: the digital signal generated based on the comparing the signal based on the charge with the first or second ramp signal with the first ramp signal; and the digital signal generated based on the comparing the signal based on the charge with the first or second ramp signal with the second ramp signal.