Passive auto-focus device and method

摘要

A passive auto-focus device and method are disclosed herein. An embodiment of the passive auto-focus device comprises: a focus-searching-range decision circuit operable to compare a range of a variation area of a current scene with a predetermined range and determine a focus-searching range, in which the variation area is defined according to the comparison between the current scene and a preceding scene; a focal-distance-variation decision circuit operable to compare the definition pertaining to the focus-searching range with a first predetermined definition and generate a current step setting value; an image record generating circuit operable to generate first step image records in connection with the focus-searching range while the current step setting value indicates a first step and to generate second step image records in connection with the focus-searching range while the current step setting value indicates a second step, in which the first step is shorter than the second step.

主权项

1. A passive auto-focus device, comprising:
a focus-searching-range decision circuit operable to compare a range of a variation area of a current scene with a predetermined range so as to determine a focus-searching range, in which the variation area of the current scene is defined according to the comparison between the current scene and a preceding scene; a focal-distance-variation decision circuit operable to generate a current step setting value according to the focus-searching range or by comparing the definition pertaining to the focus-searching range with a first predetermined definition; and an image record generating circuit operable to generate a plurality of first step image records in connection with the focus-searching range when the current step setting value indicates a first step, and generate a plurality of second step image records in connection with the focus-searching range when the current step setting value indicates a second step, in which the first step is shorter than the second step.