Adaptive Laser Control for Accurate Display Light Output
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Solution Overview
Problem
Existing laser control systems for laser-driven displays struggle with inaccurate prediction of light intensity due to non-linear optical-electrical responses and variations in laser threshold caused by temperature, unit-to-unit variability, and aging, leading to poor image quality.
Innovation Solution
A dual-control system comprising a primary control system using a PID controller and a secondary control system with a steepest descent controller iteratively measures and updates a laser model to minimize errors across various drive conditions, including different light levels, pulse timings, and disturbance conditions, using multiple-input multiple-output (MIMO) controllers to refine the light-to-current curve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single control system is used to control laser output, then the device complexity is low, but the light intensity prediction accuracy deteriorates due to non-linear optical-electrical response and varying laser threshold
Solution Approach 1:
The control system is divided into two independent control systems: a primary control system that operates continuously for real-time laser control, and a secondary control system that performs periodic calibration at different drive conditions. This segmentation allows each subsystem to have specialized functions, improving overall prediction accuracy without requiring complete system redesign.
Solution Approach 2:
The secondary control system performs preliminary calibration measurements at multiple drive conditions (different currents and pulse spacings) to build a comprehensive laser model before normal operation. This preliminary action captures the non-linear optical-electrical response and threshold variations, which are then used by the primary control system to compensate for these effects during actual display operation.
2Adaptability or versatility
If the laser model is calibrated for multiple drive conditions, then the adaptability to varying operating conditions improves, but the calibration time and measurement requirements increase
Solution Approach 1:
The secondary control system performs calibration measurements periodically or intermittently rather than continuously, operating in time-multiplexed fashion with the primary control system. This periodic calibration approach captures variations in laser threshold due to temperature, aging, and other factors without requiring continuous multi-condition measurements, thus reducing overall calibration time while maintaining adaptability.
Solution Approach 2:
The laser model is designed to be dynamic and adaptive, automatically adjusting parameters based on measurements from the secondary control system at different drive conditions. The model incorporates pulse-spacing-dependent threshold corrections and non-linear optical-electrical response compensation, allowing the system to adapt to varying operating conditions without manual recalibration.
3Ease of operation
If the primary control system operates at a single drive condition, then the control simplicity is maintained, but the image quality deteriorates due to non-linear response at different light levels
Solution Approach 1:
The secondary control system provides feedback measurements at multiple drive conditions that are used to update the laser model parameters. This feedback loop captures the non-linear optical-electrical response and pulse-spacing-dependent threshold variations, enabling the primary control system to compensate for these effects and maintain image quality across different light levels while keeping the primary control logic simple.
Solution Approach 2:
The system changes operational parameters by having the secondary control system measure at multiple drive currents and pulse spacings to build a comprehensive laser model. The primary control system then uses this model to calculate corrected drive currents that account for non-linearities and threshold variations, maintaining image quality without complicating the primary control operation.
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 dual-control system provides more accurate light intensity prediction, enhancing image quality by minimizing errors and ensuring consistent display performance despite variations in laser behavior over time and environment.
Implementation Method 1
The actual light intensity can be determined by a photodiode that receives a portion of light generated by the laser
Data Source
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AI summary
Systems, devices, methods, and computer-readable media for driving a laser of a laser-driven display. A method includes determining a first error between a first expected light intensity and a first actual light intensity from the laser at a specified control light intensity and specified control pulse spacing, determining a second error between a second expected light intensity and a second actual light intensity from the laser at a specified second light intensity and specified second pulse spacing, updating, by the secondary control system and based on the second error, a laser model resulting in an updated laser model, the laser model indicating respective driving currents to generate respective light intensities by the laser, and driving, by a driver and at a driving current determined based on the first error and the updated laser model, the laser to generate a pixel of the laser-driven display.