Patent ID: 8334495
Filing Date: 2012-12-18
Classification: G01J,H03F

Abstract:
1. A photometric device comprising: a constant current generation circuit configured to output a constant current; a first clock signal generation circuit configured to generate a first clock signal, the first clock signal oscillating at a frequency proportional to the constant current, the first clock signal generation circuit comprising: a photoelectric conversion element configured to generate a photocurrent when receiving light; a second clock signal generation circuit configured to generate a second clock signal, the second clock signal oscillating at a frequency proportional to the photocurrent, the second clock signal generation circuit comprising: a digital signal generation circuit configured to count the number of pulses of the second clock signal, the digital signal generation circuit configured to output a digital signal including a count value of the number of pulses, the digital signal generation circuit configured to set a timing when counting of the number of pulses of the second clock signal starts and a timing when the counting finishes, based on the first clock signal.