Projector Trapezoidal Distortion Correction Using Accelerometer Thresholds
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Solution Overview
Problem
Recent projector devices often perform unnecessary trapezoidal distortion corrections due to slight vibrations or detection errors, leading to a degradation in the quality of the projection image, as they correct distortion based on the most frequent output signal from the accelerometer without considering the magnitude of vibration or shock.
Innovation Solution
A projector device that determines whether to correct trapezoidal distortion based on the magnitude of the accelerometer's output signal, only performing corrections when the detected inclination angle exceeds a predetermined threshold, thereby reducing unnecessary corrections and maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the projector device performs distortion correction based on the most frequent output signal from the accelerometer, then the distortion correction function is activated, but unnecessary corrections are performed due to slight vibrations or detection errors, degrading image quality
Solution Approach 1:
The patent changes the parameter for determining distortion correction from simple frequency counting to a combination of frequency and magnitude threshold. The correction is only performed when the output signal occurs most frequently AND exceeds a predetermined magnitude threshold, filtering out small vibrations and detection errors while maintaining correction for significant tilts.
2Productivity
If the projector device continuously updates the projection image with distortion correction, then the image remains current, but the frequent corrections due to vibrations lower the quality of the projection image
Solution Approach 1:
The patent modifies the correction activation criteria by introducing a magnitude threshold parameter. Corrections are only applied when the accelerometer output exceeds this threshold, reducing the frequency of unnecessary corrections caused by vibrations while maintaining updates for genuine tilt changes.
3Measurement precision
If the projector device uses the most frequently occurred output signal for distortion correction, then the correction is based on stable data, but detection errors or slight vibrations may still trigger incorrect corrections
Solution Approach 1:
The patent enhances the detection criterion by adding a magnitude threshold to the frequency-based selection. The system now requires both that the output signal occurs most frequently and that its magnitude exceeds a predetermined threshold, thereby filtering out detection errors and slight vibrations that would otherwise trigger incorrect corrections.
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
This approach minimizes unnecessary distortion corrections, thereby enhancing the quality of the projection image by ensuring that corrections are only made when significant vibrations or errors are detected, reducing the frequency of distortion correction operations.
Implementation Method 1
The accelerometer does not only detect static acceleration due to gravity, but also detects dynamic acceleration due to vibration or shock
Data Source
Figure 1
Figure 2A~2D
Figure 3A~3B
AI summary
A projector device (1), a method of correcting trapezoidal distortion, and a distortion correction program stored in a recording medium are provided, each of which sets a sampling time period at a predetermined value, sets a value of limit angle (AL) to be greater than a minimum angle value (α) that defines an inclination angle value subjected for distortion correction, detects inclination of the projector device (1) with respect to a horizontal surface to output a plurality of inclination angle values (X) of the projector device (1) during a current sampling time period having the predetermined value, calculates a representative angle value (Ax) of a current sampling time period based on the plurality of inclination angle values (X) of the projector device (1) that are detected for the current sampling time period, calculates the difference between the representative angle value (Ax) obtained for the current sampling time period and a representative angle value (Ax-1) obtained for a previous sampling time period, determines whether the difference in representative angle value is equal to or greater than the limit angle value (AL) to generate a determination result, and corrects trapezoidal distortion in the image to be projected based on the inclination angle values (X) detected during the current sampling time period when the determination result indicates that the difference in representative angle value is equal to or greater than the limit angle value (AL).