Reflective LCD Projection Correction for Re-Entering Light
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Solution Overview
Problem
In projection display devices using reflective liquid crystal display elements, illumination light that is not modulated returns to the illumination optical system or light source unit, causing variations in display luminance across frames due to re-entering light, which existing methods fail to adequately correct.
Innovation Solution
A video analysis unit calculates the intensity of re-entering illumination light for each pixel, considering the gamma characteristic of the reflective liquid crystal display element, and determines a correction amount based on the difference between this intensity and a reference sum, adjusting pixel values to maintain consistent luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If illumination light is used to irradiate the entire reflective liquid crystal display element, then the light utilization efficiency is improved, but the display luminance of each pixel changes due to re-entering illumination light affecting pixel values of the entire frame
Solution Approach 1:
The patent calculates the intensity of re-entering illumination light in advance for each pixel based on the frame image data, and determines correction amounts before actual display. This preliminary calculation and correction approach allows the system to compensate for luminance variations caused by re-entering light, thereby maintaining display luminance uniformity while preserving the benefit of high light utilization efficiency from full-frame illumination
2Ease of manufacture
If existing methods adjust the balance of R, G, and B by multiplying color data by a gain, then the color balance is improved, but the display luminance cannot be appropriately corrected when the amount of change varies according to gradation
Solution Approach 1:
The patent applies different correction amounts to different pixels based on their individual re-entering light intensity calculations. Instead of a uniform gain adjustment for all pixels, the system calculates and applies pixel-specific corrections based on local characteristics (pixel position, gradation value), thereby achieving accurate luminance correction that adapts to varying gradation levels across the display
Solution Approach 2:
The patent changes the correction parameter from a uniform gain factor to pixel-specific correction amounts derived from calculated re-entering light intensities. By dynamically adjusting correction parameters based on actual light intensity calculations rather than fixed gain values, the system achieves accurate luminance correction across different gradation levels
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 effectively stabilizes display luminance by correcting pixel values, addressing variations caused by re-entering illumination light, thereby improving image quality.
Implementation Method 1
illumination light other than modulated light returns to an illumination optical system or a light source unit, the modulated light being modulated according to an image to be displayed, being reflected, and being directed to a projection lens
Implementation Method 2
illumination light having the first polarized light and second polarized light
Data Source
AI summary
A video analysis unit calculates an intensity of re-entering illumination light that is first polarized light, among first polarized light entering a reflective liquid crystal display element which is included in illumination light having the first polarized light and second polarized light, for each pixel constituting a target frame, the first polarized light being reflected by the reflective liquid crystal display element without being modulated by the reflective liquid crystal display element, returning to a position closer to a light source unit, and re-entering the reflective liquid crystal display element. The video analysis unit calculates a sum obtained by summing the intensity of the re-entering illumination light calculated for all pixels. A video correction amount determining unit determines a correction amount to be added to or subtracted from a pixel value of each pixel according to a difference between the sum and a reference sum of a reference frame image.