Laser Display I-L Correction via Lookup Tables
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Solution Overview
Problem
Display apparatuses face challenges in accurately representing color gradations due to non-linear injection current-light output (I-L) characteristics of laser diodes, which result in distorted shade levels and inadequate reproduction of colors, especially in varying temperature environments.
Innovation Solution
The display apparatus employs conversion tables stored in a memory unit to correct the I-L characteristics, approximating them to desired linear characteristics by associating input shade levels with output shade levels, and a control unit retrieves and applies these tables to adjust the laser output based on temperature and light conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If laser diodes are used for image projection, then high brightness and color saturation are achieved, but non-linear I-L characteristics cause distorted shade levels and inaccurate color gradation
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction data in lookup tables that map desired linear output values to actual non-linear laser output values. These correction tables are prepared in advance and used to pre-distort the input signal, compensating for the laser's non-linear I-L characteristics before the distortion occurs during normal operation.
Solution Approach 2:
The patent employs parameter changes by adjusting the drive current parameters based on temperature variations and aging effects. The system dynamically modifies current injection levels according to stored correction data that accounts for different operating conditions, transforming the fixed non-linear I-L characteristics into a condition-dependent corrected response.
2Power
If drive current is increased to improve light output, then brightness is enhanced, but non-linear I-L characteristics cause disproportionate shade level distortion
Solution Approach 1:
The system performs preliminary correction by pre-calculating the relationship between drive current and light output at various operating points, storing this correction data in lookup tables. When operation occurs, the appropriate correction factor is retrieved and applied to linearize the output, preventing shade level distortion before it affects image quality.
Solution Approach 2:
The patent segments the drive current range into multiple operating regions, with separate correction data stored for different current levels and temperature conditions. This segmentation allows precise correction for each operating point rather than using a single correction factor, maintaining accuracy across the full dynamic range of the laser.
3Stability of the object's composition
If temperature compensation is implemented to maintain stable I-L characteristics, then color consistency is improved, but system complexity increases
Solution Approach 1:
The patent uses copying by creating a digital model of the laser's non-linear I-L characteristics through measurement and storing this model as correction data in lookup tables. This digital copy represents the physical laser's behavior and allows software-based correction without additional hardware, simplifying the overall system while achieving temperature compensation.
Solution Approach 2:
The patent replaces complex mechanical or hardware-based temperature compensation mechanisms with a software-based lookup table system. Instead of using additional optical components or mechanical adjustments to compensate for temperature effects, the system uses pre-calculated correction data accessed through software, reducing device complexity while maintaining stability.
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 solution ensures accurate representation of color gradations and shade levels, minimizing distortion and maintaining image quality across different ambient temperatures and light conditions, thereby providing consistent image projection with proper color reproduction.
Implementation Method 1
at least one laser of which the light output varies in accordance with current
Data Source
AI summary
A display apparatus for displaying video made by laser light includes at least one laser of which the light output varies in accordance with current, a storage unit configured to store at least one conversion table for correcting current-light output characteristics of the laser so as to approximate to desired characteristics, and a control unit configured to retrieve the conversion table from the storage unit to cause the at least one laser to emit light based on data converted using the conversion table.