LCD Gamma Voltage Generator Automation
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Solution Overview
Problem
Existing methods for generating gamma correction voltages for LCD displays are time-consuming, costly, and require manual optimization of precision resistors, making it difficult to achieve optimal image quality, especially for dynamic gamma correction and large displays.
Innovation Solution
A system and method using a gamma reference voltage generator with control interface logic and DACs to automatically generate and apply gamma reference voltages based on gray scale codes, reducing the need for repetitive sample-hold circuit refreshing and precision resistor inventory, enabling faster and more economical dynamic gamma voltage correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If manual optimization of precision resistors is used to generate gamma correction voltages, then gamma curve accuracy can be improved, but the process becomes time-consuming and costly
Solution Approach 1:
The patent replaces manual mechanical adjustment of precision resistors with an automated digital system using DACs (Digital-to-Analog Converters) and microcontrollers. The gamma correction voltages are generated digitally through software-controlled DACs rather than manual resistor adjustment, eliminating the time-consuming manual optimization process while maintaining or improving gamma curve accuracy through programmable precision.
Solution Approach 2:
The patent changes the fundamental parameter control method from physical resistor values to digital voltage values. By using DACs with programmable output, the system can dynamically adjust gamma correction voltages through software, allowing rapid iteration and optimization without physical component changes. This enables fast parameter tuning while maintaining manufacturing precision.
2Reliability
If external high-precision resistive voltage dividers are used to modify intrinsic gamma curves, then display performance can be improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the gamma correction functionality directly into the source driver circuitry by integrating DACs and control logic within the existing LCD driver chip. This consolidation eliminates the need for separate external resistive voltage dividers and their associated components, reducing overall device complexity while maintaining display performance through integrated gamma correction.
Solution Approach 2:
The patent makes the source driver circuitry multi-functional by incorporating gamma correction capabilities directly into the driver chip. The same integrated circuit that drives the LCD pixels also generates and adjusts gamma correction voltages through its internal DACs and control logic, eliminating the need for separate external correction circuits and reducing overall system complexity.
3Manufacturing precision
If integrated circuit mask changes are made to adjust resistor values for gamma correction, then manufacturing precision can be improved, but adaptability to different LCD panels decreases
Solution Approach 1:
The patent introduces dynamic adjustability to gamma correction by using programmable DACs controlled by microcontrollers. Instead of fixed resistor values determined during manufacturing, the system can dynamically adjust gamma correction voltages through software to match the specific characteristics of different LCD panels. This enables panel-specific optimization while maintaining manufacturing precision through digital control.
Solution Approach 2:
The patent enables parameter changes for different LCD panels through software configuration of the DACs. Each panel can have its optimal gamma curve stored in memory and loaded as needed, allowing the same hardware to be precisely adapted to multiple different panel types without requiring physical component changes or mask revisions.
4Stability of the object's composition
If repetitive sample-hold circuit refreshing is performed for gamma correction, then voltage stability can be improved, but productivity and speed decrease
Solution Approach 1:
The patent eliminates the need for repetitive sample-hold circuit refreshing by using continuous DAC output that directly provides stable gamma correction voltages. The DACs generate continuous analog voltages based on digital input values, removing the discrete refresh cycles required by sample-hold circuits. This maintains voltage stability while enabling continuous, high-speed gamma correction updates.
Solution Approach 2:
The patent replaces the mechanical sample-hold circuit refresh mechanism with a digital DAC-based voltage generation system. The DACs continuously output stable analog voltages directly from digital inputs without requiring periodic refreshing, eliminating the speed limitations and artifacts associated with repetitive sample-hold operations while maintaining voltage 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 approach allows for rapid and cost-effective optimization of gamma curves, reducing image artifacts and enabling dynamic gamma correction, particularly for large displays, by automating the generation of static and dynamic gamma curves.
Implementation Method 1
cause the gray scale codes in the first register (46) to be coupled to inputs of DACs (28-1,2 . . . m) to produce signals representative of the gamma correction voltages
Data Source
AI summary
A gamma reference voltage generator (10B) for an LCD display includes a control interface logic circuit (48) having an output bus coupled to inputs of a first register (46) having outputs coupled to inputs of a second register (42) the outputs of which are coupled to corresponding inputs of plurality of DACs (28). The control interface logic circuit receives gray scale codes representative of gamma reference voltages and transfers the codes via the output bus into the first register and controls further transfer of the codes to inputs of the DACs to instantaneously or rapidly update gamma correction voltages applied to the LCD display.