Display Panel Precharger Circuit Reduces Data Programming Time
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Solution Overview
Problem
Conventional light emitting display devices face challenges in achieving high gray scales due to manufacturing process non-uniformity and long data programming times, especially near black levels, where parasitic capacitance and voltage differences lead to increased data programming time.
Innovation Solution
The implementation of a current driving method that includes a data driver transmitting data currents and a precharger supplying precharge currents, with a ratio of precharge current to data current greater than 1, to reduce data programming time and improve gray scale representation, utilizing a pixel circuit with transistors and capacitors to efficiently charge and supply voltage to light emitting elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a current programming method is used to achieve uniform display characteristics, then manufacturing precision is improved, but data programming time increases due to parasitic capacitance
Solution Approach 1:
The patent applies preliminary action by pre-charging the data line to the target voltage level before actually programming the pixel data. This pre-charge phase prepares the data line by eliminating the voltage difference that would otherwise cause long programming times due to parasitic capacitance, thereby enabling fast data programming while maintaining uniform display characteristics across all pixels
2Device complexity
If voltage programming method is used to simplify the circuit, then device complexity is reduced, but gray scale representation accuracy deteriorates due to threshold voltage deviations
Solution Approach 1:
The patent substitutes voltage programming with current programming, replacing the voltage-based control mechanism with a current-based one. This substitution allows the use of current mirrors to transfer reference currents to pixel circuits, providing immunity to threshold voltage variations and enabling accurate gray scale representation while maintaining reasonable circuit complexity through the use of standard current mirror configurations
3Measurement precision
If high gray scales are targeted with voltage programming, then measurement precision is improved, but manufacturing precision deteriorates due to process non-uniformity
Solution Approach 1:
The patent replaces voltage programming with current programming to eliminate sensitivity to threshold voltage variations caused by manufacturing non-uniformity. By using current mirrors to transfer precise reference currents to each pixel circuit, the system achieves accurate gray scale representation that is independent of TFT threshold voltage deviations, thereby simultaneously achieving high measurement precision and manufacturing precision
Data Source
AI summary
A light emitting display device including data lines, signal lines, pixel circuits, a data driver, and a precharger. Each pixel circuit includes a first switch, a transistor, a capacitor, and a light emitting element. The precharger supplies a precharge current of X times a data current to a corresponding data line in response to a control signal. When the first switch transmits the data current provided from the corresponding data line in response to a first level scan signal while the corresponding data line is precharged, a voltage corresponding to the data current is charged in the capacitor. A current corresponding to the charged voltage is supplied to the light emitting element through the transistor in response to a second level scan signal, and the light emitting element emits light.