| 摘要 |
PURPOSE:To attain focus detection with, high accuracy especially even for a dark object by correcting a dark output from a temperature and an integration time at every a focus detecting action and subtracting the corrected dark output from a picture element output. CONSTITUTION:A photoelectric converting element 1 for monitor, a reference voltage generator 8 and a comparator 10 constitute a timer means and the element 1 controls the charge accumulating time of a photoelectric converting element string 2 for focus detection. Thus, the dark output of a photoelectric converting element string in a certain environmental temperature and a constant charge accumulating time is detected in a dark condition. A temperature detecting circuit 12 detects the environmental temperature for a focus detecting action, the above-mentioned timing means times the charge accumulating time of the photoelectric converting element and a CPU 16 corrects the dark output from the environmental temperature and the charge accumulating time. The CPU 16 obtains the dark current compensating output by subtracting the corrected dark output from the output of the photoelectric converting element string. Based on the compensating output, a focus condition is detected. |
