Pixel Circuit Self-Refresh for Display Aperture Ratio
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Solution Overview
Problem
In liquid crystal display devices, especially in mobile terminals, the reduction of power consumption while maintaining display quality is challenging, particularly in constant display modes where the aperture ratio is compromised due to increased elements and signal lines, leading to lowered brightness and contrast.
Innovation Solution
A pixel circuit configuration that includes a display element, internal node, first and second switch circuits, and capacitive elements, allowing for self-refreshing actions that restore voltage states without changing the common electrode's polarity, reducing the need for additional memory parts and signal lines, and enabling multicolored displays at low power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional memory parts and signal lines are provided to maintain display quality in constant display mode, then display quality is improved, but aperture ratio is reduced and brightness is lowered
Solution Approach 1:
The pixel circuit performs self-refreshing by using its internal capacitive elements (first capacitive element connected to pixel data, second capacitive element connected to control terminal) to maintain voltage states without external memory parts. The circuit automatically restores voltage states through self-refreshing actions, eliminating the need for additional memory components and signal lines, thereby preserving aperture ratio while maintaining display quality
Solution Approach 2:
The pixel circuit is designed to perform multiple functions using a unified structure: it serves as both the display element controller and the memory storage unit. The capacitive elements serve dual purposes as both voltage holding components and self-refreshing mechanisms, eliminating the need for separate memory parts and reducing the overall element count to maintain aperture ratio
2Use of energy by stationary object
If refreshing frequency is lowered to reduce power consumption in constant display mode, then power consumption is reduced, but voltage fluctuation occurs and display quality deteriorates
Solution Approach 1:
The first capacitive element stores the pixel data voltage in advance, and the second capacitive element is pre-configured to couple with the control terminal. When self-refreshing is needed, these pre-positioned capacitive elements immediately restore the voltage states without requiring external signal lines or increasing refreshing frequency, thus maintaining display quality while reducing power consumption
Solution Approach 2:
The pixel circuit uses its internal capacitive elements to perform automatic voltage restoration without external intervention. The control circuit activates the second switch circuit to couple the second capacitive element with the control terminal, enabling the circuit to self-refresh and maintain voltage states without requiring frequent external refreshing, thereby reducing power consumption while preserving display quality
3Reliability
If polarity inversion drive is implemented to prevent flicker, then flicker is reduced, but additional drive circuits are required which reduces aperture ratio
Solution Approach 1:
The pixel circuit performs polarity inversion automatically through its internal control circuit by activating the second switch circuit and coupling the second capacitive element with the control terminal. This self-performed polarity inversion eliminates the need for external polarity inversion drive circuits, preventing flicker while preserving aperture ratio
Solution Approach 2:
Instead of using external drive circuits to control polarity inversion, the invention inverts the approach by enabling the pixel circuit itself to perform polarity inversion through its internal capacitive elements and control switches. This internal inversion mechanism eliminates the need for additional external drive circuits, maintaining aperture ratio while effectively preventing flicker
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 configuration allows for reduced power consumption and maintained display quality by minimizing the number of elements and signal lines, enabling self-refreshing actions that automatically restore voltage states, thus reducing driver circuit usage and preventing flicker issues during polarity inversion.
Implementation Method 1
a fluctuation of electric capacity of the liquid crystal capacitive element Clc between a black display and a white display due to dielectric constant anisotropy of liquid crystal molecules
Data Source
AI summary
In a display device, a liquid crystal capacitive element is sandwiched between a pixel electrode and an opposite electrode. The pixel electrode, one end of a first switch circuit, one end of a second switch circuit and a first terminal of a second transistor form an internal node. The other terminals of the first switch circuit and the second switch circuit are connected to a source line. The second switch circuit is a series circuit composed of a first transistor and a diode. A control terminal of the first transistor, a second terminal of the second transistor and one end of a boost capacitive element form an output node. The other end of the boost capacitive element and the control terminal of the second transistor are connected to a boost line and a reference line, respectively.