Automatic focusing method

Abstract

The present invention relates to an automatic focusing method which is suitable to adjust the relative position of an optical system and a photosensitive component for leading an imaging plane to fall in a field depth range. The optical system comprises a focusing lens group. The automatic focusing method provided by the present invention firstly allows the focusing lens group and the photosensitive component to return to zero, then changes the relative position of the focusing lens group and the photosensitive component for predict an evaluation value that the imaging plane falls in the field depth range, and finally approaches toward the evaluation value until the imaging plane on the photosensitive component falls in the field depth range, thus automatic focusing is completed. During automatic focusing, as only one time of reentrant movement is needed, the speed can be greatly quickened, and the present invention can achieve the using effect of rapid focusing, little mechanical wear, long life span and low failure rate.

Description

technical field [0001] The invention relates to a focusing method, in particular to an automatic focusing method. Background technique [0002] As shown in Figures 1, 2, and 3, the autofocus function often appears in, for example, the camera system 100 of a digital camera, so that the user can quickly obtain the imaging state that the imaging plane falls within the depth of field range. 100 mainly includes a lens 10 with a focusing lens group 101, a photosensitive component 11, a signal processor 12 (DSP), a drive unit 13 that drives the focusing lens group 101 to move relative to the photosensitive component 11, and an electrical connection signal processing The controller 12 and the control unit 15 of the drive unit 13. [0003] The camera system 100 obtains an image result in which the imaging plane falls within the depth of field through an autofocus method, and the method includes the following steps: [0004] (A) When the digital camera is activated, regardless of th...

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Problems solved by technology

[0010] However, although the above method can achieve the function of autofocus, it still has unsatisfactory effects, such as:

[0011] 1. From figure 2 It can be seen from the flow chart of FIG. 3 and the graph in FIG. 3 that the movement of the focusing lens group 101 operates in the manner of "turning back and running", and its moving positions are A, B, C, D, and E in sequence. When reaching a turning position (such as B, C, D) and needing to run back, the drive unit 13 must first be suspended before reverse rotation, which takes a long time, and the mechanical wear is also large, resulting in lower life expectancy and higher failure rate. high

[0012] 2. From the moving sequence in Figure 3, it can be seen that the way of running back and forth will repeatedly go back and forth between positions E and D, and the total moving distance is longer, resulting in a longer focusing time

[0013] 3. Every time you want to take a photo to focus, you will always return to the close-up position B to return to zero. At this time, if the last photo is a long-range shot, the activation position A will inevitably be close to the long-shot position F, and the next photo It is also necessary to shoot from a distance, and the focusing lens group 101 cannot perform a close-range zeroing action at the telephoto position F, but must first return to the close-up position B. In this way, it will cause a long travel time, a long time-consuming, and a slow focusing speed.

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