Patent ID: 7389042

Claim:
An auto focus method of a digital camera for moving a lens of said digital camera to the maximum focus value position, comprising steps of: (a) calculating a focus value average FV avg of the focus values from the first step position to the Nth step position of said lens; (b) determining a lens movement state including a coarse state, a mid state and a fine state, wherein said lens moves A steps in said coarse state, B steps in said mid state and one step in said fine state, where B is less than A; (c) moving said lens and recording the focus value of said lens in said lens movement state according to said focus value average FV avg , a focus value difference FV dif , a previous maximum focus value FV max , a coarse state threshold T c , a mid state threshold T m , a focus value difference threshold T dif , a mid state count value MidCount and a downhill count value DownCount; (d) repeating steps (b) and (c) until the searching over a search range is finished; and (e) moving said lens to a right position corresponding to the maximum focus value.