Projector Keystone Correction Using Gravity Sensor
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Solution Overview
Problem
Current projector systems face inefficiencies in automatic keystone correction due to environmental factors, requiring cameras and complex calculations, which are costly and limited by screen materials and angles, especially in micro projection technology.
Innovation Solution
A projector system utilizing a gravity sensor and time-of-flight ranging device for fully automatic correction, eliminating the need for cameras and allowing dynamic micro-adjustments without manual intervention, capable of handling trapezoidal distortions across various focal lengths and light sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional automatic correction method using camera and coordinate generation is employed, then correction function is achieved, but execution efficiency is poor and accuracy is affected by ambient background light and screen conditions
Solution Approach 1:
The patent replaces the optical-mechanical camera-based coordinate detection system with a gravity sensor-based detection system. The gravity sensor detects the projector's tilt angle and orientation through gravitational force measurement, eliminating the need for camera-based image analysis. This substitution improves execution efficiency by providing direct angle measurements and enhances reliability by making correction accuracy independent of ambient light conditions and screen materials.
Solution Approach 2:
The projector system performs self-correction by using its own gravity sensor to detect its installation state and automatically calculate the keystone correction parameters. The system serves itself by eliminating the need for external cameras or positioning devices, achieving fully automatic correction without manual intervention or external辅助设备.
2Reliability
If fixed camera is used for automatic correction, then correction is achieved, but it is limited by FOV angle matching, resolution requirements, and cost
Solution Approach 1:
The patent replaces the complex optical system (lens and camera) with a simple gravity sensor system. The gravity sensor directly measures the projector's orientation angles without requiring optical path matching or high-resolution imaging. This reduces device complexity by eliminating cameras, lenses, and associated processing hardware while maintaining correction stability through direct gravitational measurement.
Solution Approach 2:
The gravity sensor-based system is universal and can be applied to projectors with any FOV angle, including ultra-short throw projectors. Unlike camera-based systems that require specific FOV matching and resolution requirements, the gravity sensor measures orientation independently of projection parameters, making the correction system universally applicable across different projector types without additional complexity.
3Manufacturing precision
If manual adjustment is used for keystone correction, then picture distortion can be corrected, but it requires user intervention and repeated adjustments
Solution Approach 1:
The projector automatically detects its installation angle using the gravity sensor and calculates the required keystone correction parameters without user intervention. The system performs self-correction by adjusting the projected image based on the detected tilt angle, eliminating the need for manual keystone adjustment operations while maintaining high correction accuracy.
Solution Approach 2:
The gravity sensor continuously provides feedback on the projector's orientation angle, and the control system uses this feedback to automatically adjust the keystone correction parameters. This closed-loop feedback mechanism ensures accurate correction while eliminating manual operation, as the system automatically responds to changes in installation angle.
4Measurement precision
If TOF ranging device is used in ultra-short throw projector, then ranging is achieved, but large error rate occurs when taking FOV line in short distance
Solution Approach 1:
The patent replaces the TOF ranging device with a gravity sensor-based orientation detection system. Instead of measuring distance through light time-of-flight (which has high error rates at short distances in ultra-short throw projectors), the system measures the projector's tilt angle directly through gravitational force. This substitution eliminates the ranging error problem while maintaining measurement precision for keystone correction.
Solution Approach 2:
The patent changes the measurement parameter from distance (ranging) to orientation angle. By measuring the tilt angle through which the projector is installed rather than the distance to the projection surface, the system avoids the short-distance ranging errors inherent in TOF devices. The gravity sensor accurately measures orientation angles regardless of projection distance, making it suitable for ultra-short throw applications.
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 rapid and accurate automatic keystone correction, maintaining aspect ratios and reducing the need for manual adjustments, suitable for ultra-short throw projectors and diverse environments, with no additional positioning devices required.
Implementation Method 1
The processor is configured to obtain a tilt angle of the projector by using a gravity sensor
Implementation Method 2
a time of flight (TOF) ranging device to correct the error perpendicular to the normal line
Data Source
AI summary
An automatic keystone correction method for projector system includes obtaining full field of view coordinates of a projecting picture being projected to a plane by a time of flight (TOF) ranging device as a first reference picture, utilizing the Gravity sensor to calibrate TOF scanning time deviation, and constructing a motion virtual line of a fixed field of view (FOV) through calibrating its horizontal and vertical angle to implement a rectangle adjustment function.