Patent ID: 8040427
Filing Date: 2011-10-18
Classification: G02B,G03B

Abstract:
1. An imaging device that converts an optical image, which is captured via an optical system having a focusing function, into a video signal, the imaging device comprising: a high frequency component extractor that adjusts the video signal with a preset gain controlled according to an imaging condition and detects intensity of at least a specific signal in a certain frequency band, which includes a high frequency component and is generated in a focus state of the optical image captured via the optical system, from the adjusted video signal; a learning module that learns an offset value based on the intensity of the specific signal detected in an out-of-focus state of the optical image captured via the optical system; and an optical system controller that refers to the learnt offset value to estimate an adjustment direction of the optical system giving a peak of the detected intensity of the specific signal, and controls the optical system in the estimated adjustment direction to be set in the focus state; wherein the optical system controller has a focus state identification module that specifies the peak of the detected intensity of the specific signal by referring to the learnt offset value and identifies the focus state of the optical system to give the peak of the detected intensity of the specific signal, and the optical system controller controls the optical system to be set in the identified focus state; and wherein in the course of the control of the optical system in the estimated adjustment direction to be set in the focus state, when the detected intensity of the specific signal decreases below a threshold value that is computed from the learnt offset value and a detected maximum intensity of the specific signal, the optical system controller specifies the detected maximum intensity of the specific signal as the peak of the intensity of the specific signal.