Pixel Circuit Using Analog Comparator for Multi-Gray-Scale Display
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Solution Overview
Problem
Traditional pixel circuits are complex, leading to decreased pixel density due to numerous components and wavelength changes with light-emitting current, affecting color reproducibility and requiring more display area.
Innovation Solution
A simplified pixel circuit structure incorporating a light-emitting module, a driving module, and an analog comparator that controls conduction time and degree using triangle-wave and brightness control signals, allowing for multi-gray-scale display without the need for traditional data signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a traditional pixel circuit structure with multiple transistors and capacitors is used, then the circuit can achieve multi-gray-scale display, but the circuit complexity increases and the display area occupied increases
Solution Approach 1:
The patent extracts the gray-scale control function from the traditional complex pixel circuit and implements it externally through a driver circuit that generates PWM signals. This removes the need for multiple transistors and capacitors within the pixel circuit itself, significantly reducing circuit complexity while maintaining multi-gray-scale display capability
Solution Approach 2:
The simplified pixel circuit uses a single transistor that serves multiple functions: data writing, storage, and light emission control. The external driver circuit provides universal PWM signal generation that can control multiple pixels, replacing the need for separate control circuits in each pixel
2Adaptability or versatility
If a traditional pixel circuit structure with multiple transistors and capacitors is used, then the circuit can achieve multi-gray-scale display, but the display area occupied increases
Solution Approach 1:
By extracting the gray-scale control functionality from the pixel circuit to an external driver, the patent eliminates the need for large storage capacitors and multiple transistors within each pixel, thereby reducing the area occupied by each pixel while maintaining full multi-gray-scale capability through external PWM control
Solution Approach 2:
The patent employs periodic PWM (Pulse Width Modulation) signals from the external driver to control the single transistor in each pixel, enabling multi-gray-scale display through time-multiplexed control rather than requiring multiple parallel control paths, thus reducing the area needed for control circuitry
3Illumination intensity
If pulse amplitude modulation driving mode is used with traditional pixel circuit, then light-emitting current can be controlled, but wavelength changes with current causing decrease in color reproducibility
Solution Approach 1:
The patent replaces amplitude modulation with periodic pulse width modulation to control light emission. By varying the duty cycle of fixed-amplitude PWM pulses rather than the amplitude itself, the system maintains constant current amplitude during light emission, thereby controlling brightness through time averaging while preserving color reproducibility
Solution Approach 2:
The external driver circuit preliminarily processes the gray-scale information and converts it into appropriate PWM signal patterns before they reach the pixel circuit. This preliminary conversion ensures that the transistor receives clean, well-timed control signals that maintain stable current characteristics during the actual light-emitting phase
Data Source
AI summary
The present disclosure provides a pixel circuit and a display panel. The pixel circuit controls a conduction time of the driving module according to a connected triangle-wave analog signal, a time controlling analog signal, and a brightness control analog signal connected through an analog comparator, and controls a conduction degree of the driving module according to a brightness control analog signal connected through the analog comparator; thus a light-emitting time and/or luminous brightness of a light-emitting module is controlled, and multi-gray-scale display with a simpler pixel circuit structure is realized.