Projector Autofocus Using Motion Sensing and Continuous Ranging
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Solution Overview
Problem
Conventional projector autofocus systems require time-consuming recalibration of distance sensors when moved, causing image blurriness and reduced practicality.
Innovation Solution
Incorporation of an inertial sensor and ranging unit to dynamically adjust the projector's focal length based on motion detection and continuous distance measurement, allowing for rapid focus adjustment during movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the projector uses built-in distance sensors to measure distance and adjust focal length, then the autofocus function can be achieved, but the adjustment process takes several seconds or longer causing image blurriness
Solution Approach 1:
The inertial sensor continuously monitors projector movement in advance, and when movement is detected, the system proactively switches to the second mode and activates the ranging unit before the user notices image blurriness, thereby reducing the perceived focus adjustment time
Solution Approach 2:
The system dynamically switches between two operating modes based on real-time inertial sensor data: the first mode for stationary projection and the second mode for moving projection. This dynamic adaptation allows the system to optimize focus adjustment speed according to the actual projection state
2Measurement precision
If the projector relies on traditional distance sensor remeasurement after movement, then accurate distance data can be obtained, but the user experience is degraded due to visible blurriness during adjustment
Solution Approach 1:
In the second mode, the ranging unit continuously detects distance and the processor continuously generates focusing signals to the focusing motor, maintaining continuous focus adjustment during projector movement rather than performing discrete adjustments, which eliminates visible blurriness and improves user experience
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables clear imaging during projector movement and rapid focus recovery upon stabilization, enhancing user experience and efficiency.
Implementation Method 1
an inertial sensor, configured to continuously detect a motion state of the projector to generate an inertial sensing signal
Implementation Method 2
the ranging unit continuously detects a distance between the projector and the projection surface to generate a distance signal
Implementation Method 3
the processor generates a corresponding focusing signal to the focusing motor of the lens module according to the distance signal so as to drive the focusing motor to adjust the focal length of the projection lens
Data Source
AI summary
A projector and an autofocus method are provided. The projector includes a ranging unit, an inertial sensor, a control module, and a lens module. The lens module includes a projection lens and a focusing motor. When the projector is in a first mode, the control module compares an inertial sensing signal with an activation threshold to generate a first comparison result, and determines accordingly whether to switch the projector from the first mode to a second mode. When the projector is in the second mode, the ranging unit continuously detects a distance between the projector and a projection surface to generate a distance signal, and the control module generates a corresponding focusing signal to the focusing motor according to the distance signal so as to drive the focusing motor to adjust a focal length of the projection lens according to the focusing signal.