Projector Optical Path Asymmetry for Illuminance Uniformity
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Solution Overview
Problem
Conventional projectors experience issues with illuminance distribution imbalance and color unevenness due to differences in optical path lengths and reflection numbers, leading to relative inversion of images and decreased illuminance, especially when light source intensity varies or component positions shift.
Innovation Solution
A projector design with a light source emitting first and second color lights, a color separation and light guide system, and light modulation units with specific optical path lengths and reflection surface configurations to prevent relative inversion and maintain balanced illuminance, using a cross dichroic prism to combine images from light modulation devices, ensuring symmetry and equalization of image formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the optical path lengths for different color lights are equalized by adding relay lenses, then the illuminance distributions are relatively equalized, but the number of lenses increases and illuminance decreases
Solution Approach 1:
The patent deliberately creates asymmetric optical path lengths for different color lights (red, green, blue) passing through the liquid crystal light valves. By making the optical path lengths unequal and adjusting the number of reflections to be odd for all colors, the patent achieves illuminance distribution equalization without requiring additional relay lenses, thus avoiding increase in device complexity and illuminance loss.
2Manufacturing precision
If relay lenses are added to correct illuminance distributions, then color unevenness is reduced, but illuminance decreases
Solution Approach 1:
The patent uses asymmetric optical path design where the optical path lengths for red, green, and blue lights are intentionally made unequal. By controlling the number of reflections to be odd for all color paths and positioning liquid crystal light valves at different distances from the projection lens, the patent achieves color uniformity without adding relay lenses, thereby preventing illuminance decrease.
3Manufacturing precision
If the number of reflections on optical paths is made odd or even to equalize optical lengths, then illuminance distributions become relatively equal, but images may be inverted
Solution Approach 1:
The patent creates an asymmetric configuration where liquid crystal light valves for different colors are positioned at different distances from the projection lens along the optical axis. This asymmetric positioning, combined with odd number of reflections for all color paths, achieves both illuminance distribution equalization and correct image orientation without requiring additional optical elements.
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
The solution prevents relative inversion and maintains balanced illuminance across color images, reducing color unevenness and white balance deterioration even when light source conditions change, without increasing the number of lenses or inverting images, thus enhancing projection image quality.
Implementation Method 1
a color separation and light guide system which separates light emitted from the light source into the first color light and the second color light
Implementation Method 2
a color separation and light guide system which separates light emitted from the light source into the first color light and the second color light
Implementation Method 3
three liquid crystal light valves illuminated by the illumination lights in three colors
Implementation Method 4
an illumination system which equalizes light emitted from the light source and converts the light into polarized light
Implementation Method 5
a cross dichroic prism which combines images received from the three liquid crystal light valves
Implementation Method 6
a cross dichroic prism which combines images received from the three liquid crystal light valves
Data Source
AI summary
A projector can form images of illumination system on respective optical paths at positions of corresponding liquid crystal display panels with respect to a light emission surface of a cross dichroic prism without relatively inverting the images and without increasing the number of lenses from the number of lenses included in a relay optical path structure in related art. Moreover, the projector can equalize the magnification of the images formed on the respective liquid crystal display panels by controlling relative image-forming conditions of the first and second optical paths in advance. Thus, deterioration of white balance and color unevenness of light projected by the projector can be reduced even when light emission distribution of a light source varies with elapse of time, for example.