LCoS Display Brightness Adjustment via Gain Control Circuit
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Solution Overview
Problem
Liquid Crystal on Silicon (LCoS) displays face challenges in maintaining balanced brightness across the image due to attenuation of light beam intensity, leading to brightness unbalance and potential color shifts as light travels through the polarization beam splitter (PBS).
Innovation Solution
A gain control circuit is introduced to adjust brightness values based on their coordinates, determining gains that compensate for attenuation by applying different multipliers to red, green, and blue brightness values, ensuring consistent output across the image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light beam passes through the polarization beam splitter (PBS) in the LCoS display, then the display achieves high aperture ratio and resolution, but the light beam intensity is attenuated causing brightness unbalance
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing compensation values in a lookup table before display operation. The gain control circuit retrieves these pre-computed values based on pixel coordinates to compensate for brightness attenuation, avoiding real-time calculations and enabling efficient brightness uniformity correction.
Solution Approach 2:
The patent implements local quality by applying different compensation values to different regions of the display panel. The compensation value varies according to the pixel's coordinate position, with greater compensation applied to regions experiencing more severe attenuation. This spatially-varying compensation approach addresses the non-uniform brightness distribution caused by the PBS.
2Measurement precision
If the LCoS panel rotates light polarization to control image brightness, then high resolution is achieved, but color shifts occur due to PBS magnitude changes
Solution Approach 1:
The patent applies local quality by using different compensation values for different color channels (R, G, B) at each pixel location. The gain control circuit retrieves three separate compensation values from the lookup table for each pixel, corresponding to the three primary colors. This allows independent correction of color balance at each spatial position, maintaining color consistency while preserving high resolution.
Solution Approach 2:
The patent implements feedback by using measured or characterized attenuation data to populate the lookup table with compensation values. The system incorporates feedback from the optical path characteristics to adjust the compensation values, ensuring that color shifts are corrected based on actual system performance rather than theoretical models alone.
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 balances brightness across the image, preventing unbalanced light distribution and color shifts, thereby enhancing the display's overall brightness adjustment and image quality.
Implementation Method 1
a polarization beam splitter (PBS)... The PBS reflects the light beam to the LCoS panel... the light beam passes through the PBS to human eyes
Implementation Method 2
The transistors in the LCoS panel are configured to rotate the polarization of the light beam by applying an electric field on the liquid crystal
Implementation Method 3
The aluminium electrodes reflect the light beam, and the light beam passes through the PBS to human eyes
Data Source
AI summary
The liquid crystal on silicon (LCoS) display includes a polarization beam splitter (PBS), a light source, a LCoS panel and a gain control circuit. The PBS has a first side and a second side. The light source is disposed at the first side of the PBS. The gain control circuit receives brightness values. Each of the brightness values has a coordinate which is based on a coordinate axis extending from the first side of the PBS to the second side. The coordinate of a first brightness value is less than the coordinate of a second brightness value. The gain control circuit determines gains according to the coordinates, and adjusting the brightness values according to the gains, in which the gain of the first brightness value is less than the gain of the second brightness value.