Separate Ladder Resistors for LCD Polarity Voltage Generation
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Solution Overview
Problem
Conventional gradation display reference voltage generating circuits for liquid crystal display devices face challenges in reducing footprint and power consumption while maintaining suitable gradation display voltages for both positive and negative polarity drives, which are often different in characteristic, leading to increased current consumption and the need for intermediate voltage corrections.
Innovation Solution
A gradation display reference voltage generating circuit with two integrated liquid crystal driving voltage producing circuits, each with separate resistor division circuits for positive and negative polarities, using ladder resistor circuits and power supply isolation to reduce current consumption and eliminate the need for intermediate voltage corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single resistance division circuit is used for both positive and negative polarity drives, then the device complexity is reduced, but the manufacturing precision deteriorates because the γ characteristics differ between polarities
Solution Approach 1:
The patent divides the single resistance division circuit into two separate circuits: a first resistance division circuit for positive polarity drive and a second resistance division circuit for negative polarity drive. Each circuit is independently designed with resistance ratios optimized for its specific polarity's γ characteristics, thereby maintaining manufacturing precision while managing device complexity through functional segmentation.
Solution Approach 2:
The patent applies different resistance ratios in different parts of the system based on local requirements. The first resistance division circuit uses a first resistance ratio optimized for positive polarity γ characteristics, while the second resistance division circuit uses a second resistance ratio optimized for negative polarity γ characteristics. This local optimization ensures precise gradation display for each polarity independently.
2Manufacturing precision
If separate resistance division circuits are used for positive and negative polarities, then the manufacturing precision is improved, but the device complexity increases
Solution Approach 1:
The patent designs both resistance division circuits to operate from a common power supply voltage and produce multiple reference voltages (V0-V63) that serve both positive and negative polarity drives. The first and second resistance division circuits are integrated into a unified reference voltage generating circuit that provides universal reference voltages for the entire display system, reducing the need for separate power supply circuits.
Solution Approach 2:
The patent merges the two resistance division circuits into a single integrated reference voltage generating circuit block. Both the first resistance division circuit (with resistors RH0-RH64) and the second resistance division circuit (with resistors RL64-RL0) are combined to share common power supply connections and output structures, thereby managing device complexity through consolidation while maintaining separate functional paths for each polarity.
3Manufacturing precision
If intermediate voltage input terminals are added for correction, then the manufacturing precision is improved, but the device complexity and footprint increase
Solution Approach 1:
The patent performs preliminary correction by designing the resistance ratios of the first and second resistance division circuits to inherently compensate for γ characteristic differences between polarities. The resistance ratios are pre-calculated and built into the circuit during manufacturing, eliminating the need for runtime voltage corrections or additional intermediate voltage input terminals. This preliminary design approach achieves manufacturing precision without adding circuit complexity.
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 reduces power consumption and footprint, ensures suitable gradation display voltages for each polarity, and eliminates the requirement for intermediate voltage input terminals, thereby enhancing display quality and efficiency.
Implementation Method 1
a first ladder resistor circuit in which a plurality of first resistance elements are connected in series between two different power supplies and which produces the plurality of first reference voltages by resistance division of a difference in voltage between the two power supplies
Data Source
AI summary
In a gradation display reference voltage generating circuit, first reference voltages (VH0 to VH63) produced by resistors for positive polarity (RH0 to RH64) of a first ladder circuit in a first reference voltage producing section (LDH) are output from reference voltage output terminals (T0 to T63), respectively, at the positive polarity drive, while second reference voltages (VL0 to VL63) produced by resistors for negative polarity (RL0 to RL64) of a second ladder circuit in a second reference voltage producing section (LDL) are output from the reference voltage outputs (T0 to T63), respectively, at the negative polarity drive. A resistance ratio of the resistors for positive polarity (RH0 to RH64) is different from a resistance ratio of the resistors for negative polarity (RL0 to RL64).