Projection Device Luminance Correction for Trapezoidal Distortion
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Solution Overview
Problem
Conventional projection devices fail to maintain uniform illuminance distribution of projected images, especially when the screen is not vertically aligned or when trapezoidal corrections are made, leading to degraded display quality.
Innovation Solution
A projection device equipped with detection means to assess the luminance distribution and correction means to adjust the light image based on trapezoidal distortion states, ensuring uniform illuminance distribution by adjusting the light image formation and luminance distribution accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a LED array with uniform illuminance distribution is used as the light source, then the illuminance distribution at the light source is uniform, but the illuminance distribution of the projected image becomes non-uniform when trapezoidal correction is applied
Solution Approach 1:
The patent applies local quality by creating a non-uniform illuminance distribution pattern in the LED array that corresponds to the specific projection situation. Instead of using a uniform illuminance distribution, the system adjusts the illuminance at different locations of the LED array to compensate for the non-uniformity introduced by trapezoidal correction, thereby achieving uniform illuminance in the projected image.
Solution Approach 2:
The patent implements preliminary action by pre-calculating and setting the appropriate illuminance distribution pattern in the LED array before projection begins. The control unit determines the required illuminance distribution based on the projection situation (including trapezoidal correction requirements) and adjusts the LED array accordingly in advance, so that when projection occurs, the illuminance is already optimized for the specific situation.
2Adaptability or versatility
If trapezoidal correction is applied to accommodate oblique screen projection, then the projection adaptability is improved, but the image density uniformity deteriorates
Solution Approach 1:
The patent applies feedback by using an image sensor to detect the actual luminance distribution of the projected image. The control unit receives this feedback information and uses it to adjust the illuminance distribution pattern in the LED array, thereby compensating for the non-uniformity caused by trapezoidal correction and achieving uniform image density.
3Adaptability or versatility
If the screen is arranged obliquely to the projected optical axis, then the projection versatility is improved, but the illuminance distribution uniformity of the projected image deteriorates
Solution Approach 1:
The patent implements dynamics by making the illuminance distribution pattern in the LED array adjustable and adaptable to different projection situations. The control unit can dynamically change the illuminance distribution pattern based on the screen arrangement and projection geometry, allowing the system to maintain uniform illuminance in the projected image regardless of the screen's angular position.
Data Source
AI summary
There is disclosed a projection device which includes a light source constituted of a reflector and a light source lamp, a projection system including a projection encoder for forming a light image based on an input image signal to project it by use of light from the light source, a micromirror element and a projection lens, a photographing system including a photographing lens for photographing the projected image, a CCD and a process circuit, and a control section detecting a luminance distribution from the photographed image and correcting a luminance distribution of the light image formed by the micromirror element in accordance with the detected luminance distribution.