How to Autofocus a Projector

Abstract

An autofocus method for a projector, based on an autofocus component of the projector, the method sets an anchor point, an effective focus range, a coarse focus point and a fine focus point, by means of an image sensor, a data processor, a drive motor and an optical lens The negative feedback control mechanism composed of the group finds the optimal fine-focus image quality and the best fine-focus point through the coarse focus process and the fine focus process, and accordingly shifts the optical lens group to the best focal length position to complete autofocus. By setting the anchor point, the present invention shields the difference problem caused by the projector using different optical lens groups in the focusing process, and expands the scope of application of the present invention; by setting the effective focus range, the automatic focus speed is improved; by setting the focus starting point , to ensure the accuracy of auto focus.

Description

technical field [0001] The invention relates to a negative feedback displacement adjustment method, in particular to a method for automatically moving a lens of a projector to complete focusing. Background technique [0002] Classified by the focal length of the lens, projectors in the prior art include fixed-focus projectors and adjustable-focus projectors. The focal length of the fixed-focus projector lens group is fixed, so the placement position of the projector is also fixed, which limits the application occasions. The focus projector can adjust the focal length of the lens group to complete the focus to adapt to more applications, including manual focus projectors and auto focus projectors. Manual focus projectors require users to complete the focusing process by themselves according to their own observation of the projected image quality, which is likely to cause inconvenience to users and poor user experience. Although the auto-focus projector can complete the focu...

AI Technical Summary

Problems solved by technology

[0003] 1. Some auto-focus projectors in the prior art adopt the method of estimating the focus, extracting several points within the travel range of the lens group to make a preliminary judgment on the projected image, thereby estimating the focal length position, and completing the focus; due to errors in the estimation, the success rate of auto-focus is low. Low, not suitable for projectors with a large travel range of the focusing mechanism, and projectors with low focusing accuracy, and the applicable range is small;

[0004] 2. Another part of the existing auto-focus projectors uses the gradual approach method to focus. Although this method improves the success rate of auto-focus, the focusing process is slow and the focusing efficiency is low. It is not suitable for projectors with a large focus range.

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