Patent ID: 8330834

Claim:
A signal processing method for a solid-state image sensing device including: a pixel for photoelectrically generating a photoelectron by light and storing the photoelectron; and an A/D converter for converting an analog signal, which is read from the pixel based on the stored photoelectron, into a digital signal; the A/D converter including a frequency divider which receives a pulse train depending on the analog signal read from the pixel and which is able to change a frequency dividing ratio into an arbitrary dividing ratio, and a counter circuit for counting the frequency-divided pulses; the signal processing method comprising: a first reading step of reading repeatedly M times, with the A/D converter, a first pulse train depending on an analog signal having a black level from the pixel, during a first A/D conversion period in which the analog signal having a black level is converted into a digital signal; a first frequency-dividing step of frequency-dividing by M, with the frequency divider, frequency-dividing pulses of the first pulse train which is read repeatedly M times; a first counting step of counting, with the counter circuit, pulses of the first pulse train, which is read repeatedly M times and frequency-divided by M; a second reading step of reading repeatedly N times, with the A/D converter, a second pulse train depending on an analog signal having a signal level from the pixel, during a second A/D conversion period in which the analog signal having the signal level is converted into a digital signal; a second frequency-dividing step of frequency-dividing by N, with the frequency divider, frequency-dividing pulses of the second pulse train which is read repeatedly N times; and a second counting step of counting, with the counter circuit, pulses of the second pulse train, which is read repeatedly N times and frequency-divided by N, wherein M and N satisfy the relationship N≦M.