Overdriven fLCOS Panel Drive Waveform for Optical Performance
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Solution Overview
Problem
Designing virtual and augmented reality head-mounted devices with near-eye displays that balance aesthetics, power efficiency, and optical performance is challenging, as existing components can be unsightly, bulky, and inefficient.
Innovation Solution
Incorporating a ferroelectric liquid crystal on silicon (fLCOS) display panel with illumination optics and a waveguide, controlled by control circuitry that selects non-square wave drive voltage waveforms based on temperature sensor data and frame history to optimize reflectance and optical performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a square wave drive voltage waveform is used to drive the fLCOS display panel, then the device complexity is reduced and ease of operation is improved, but the optical performance (reflectance) deteriorates and response time increases
Solution Approach 1:
The patent changes the parameter of drive voltage waveform from a simple square wave to a non-square wave waveform with specific characteristics (higher peak voltage, controlled duration). This parameter change optimizes the reflectance and response time of the fLCOS display panel while maintaining controllable device operation through systematic waveform selection based on temperature and frame history.
2Reliability
If the drive voltage waveform is optimized for maximum reflectance, then optical performance is improved, but the device complexity increases due to temperature sensing and waveform selection circuitry
Solution Approach 1:
The patent implements feedback mechanisms by using temperature sensors to monitor operating conditions and using frame history information to track display state. This feedback enables the control circuitry to automatically select appropriate drive waveforms, optimizing optical performance without requiring complex manual intervention or overly complicated control systems.
Solution Approach 2:
The patent applies preliminary action by pre-characterizing the fLCOS display panel's response to different drive waveforms at various temperatures and frame histories. This allows the control circuitry to select from pre-determined optimal waveforms rather than performing complex real-time optimization, reducing the computational burden and circuit complexity.
3Productivity
If the fLCOS display panel response time is reduced through overdriving, then productivity is improved, but use of energy increases due to higher peak voltages
Solution Approach 1:
The patent uses periodic action by applying drive voltage waveforms with specific temporal characteristics - high peak voltages for brief durations followed by lower voltage periods. This periodic structure with controlled pulse widths achieves fast response times while limiting overall energy consumption, as the high-voltage states are maintained only long enough to achieve the desired optical transition.
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 enhances the optical performance and power efficiency of near-eye displays by optimizing the fLCOS panel's reflectance and response time across varying temperatures and frame histories, ensuring better image quality and reduced power consumption.
Implementation Method 1
The fLCOS display panel may modulate image data (e.g., image frames) onto the illumination light to produce image light
Implementation Method 2
a spatial light modulator such as a ferroelectric liquid crystal on silicon (fLCOS) display panel
Implementation Method 3
The waveguide may direct the image light towards an eye box
Implementation Method 4
The control circuitry may control the fLCOS panel to produce the image light by driving the fLCOS panel using the selected non-square wave drive voltage waveform
Data Source
AI summary
A display may include illumination optics, a ferroelectric liquid crystal on silicon (fLCOS) panel, and a waveguide. The display may include a temperature sensor that gathers temperature sensor data. Control circuitry may select a non-square wave drive voltage waveform based on the gathered temperature sensor data and/or based on frame history information for the fLCOS display panel. The control circuitry may control the fLCOS panel to produce image light by driving the fLCOS panel using the selected non-square wave drive voltage waveform. The non-square wave drive voltage waveform may be an overdrive waveform or an underdrive waveform. This may serve to optimize the reflectance of the fLCOS display panel and thus the optical performance of the display module regardless of operating temperature and frame history.