Patent ID: 8730379
Filing Date: 2014-05-20
Classification: G03B,H04N

Abstract:
1. An auto-focus method configured for controlling a motor to driving an optical lens of a lens module to a focus point, comprising: selecting three different current values from a working electric current range of the motor at random; inputting the three different current values to the motor one after the other, driving the focusing lens to three different positions and capturing three different images at the three different positions; analyzing the images and acquiring a resolution value of each image; building a coordinate system, wherein the current value serves as abscissa and the resolution value serves as ordinate; defining three coordinate points in the coordinate system according to the current values and the resolution values; describing a first parabola passing through the three coordinate points in the coordinate system; acquiring a current value of a first highest point of the first parabola; inputting the current value of the first highest point to the motor, driving the focusing lens to a position and capturing an image at that position; analyzing the image at the position corresponding to the first highest point and acquiring a resolution value of this image; defining a fourth coordinate point in the coordinate system according to the current value of the first highest point and the resolution value of the image at the position corresponding to the first highest point; describing a second parabola passing through the fourth coordinate point and two coordinate points selected from the first coordinate point, the second coordinate point, and the third coordinate point in the coordinate system, wherein the resolution values of two selected coordinate points are greater than that of unselected coordinate point; acquiring a current value of the second highest point of the second parabola; comparing a first difference between the current value of the second highest point and the current value of the first highest point with a preset value; and regarding the second highest point as the focus point upon a condition that the first difference is less than the preset value.