Mixed-Type TFT Pixel Circuits for Low-Frequency Display Driving
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Solution Overview
Problem
Existing display devices face challenges in reducing power consumption, particularly when displaying still images or operating in always-on-display mode.
Innovation Solution
The display device incorporates a pixel structure with switching elements of different types, including poly-silicon and oxide thin film transistors, and employs a low-frequency driving mode where the gate clock signal is maintained at a direct current during the holding frame, and the data driver is not operated during this frame to minimize power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If low-frequency driving mode is used to reduce power consumption, then energy efficiency is improved, but image quality may deteriorate due to leakage currents
Solution Approach 1:
The pixel circuit is segmented into multiple switching elements with different characteristics (first type and second type). The first switching element handles primary switching while the second switching element compensates for leakage currents, allowing low-frequency driving without image quality degradation.
Solution Approach 2:
The invention changes the electrical parameters of the pixel circuit by introducing switching elements with different threshold voltages and leakage characteristics. This parameter differentiation enables effective leakage compensation during low-frequency driving modes.
2Use of energy by moving object
If holding frame is used to maintain displayed data, then power consumption is reduced by not refreshing data, but leakage currents cause luminance inconsistency
Solution Approach 1:
The pixel circuit performs self-compensation for leakage currents during the holding frame period. The second switching element automatically compensates for leakage without requiring external intervention or additional power consumption, maintaining luminance consistency autonomously.
Solution Approach 2:
The invention merges the functions of data holding and leakage compensation into a single pixel circuit structure. The combination of multiple switching elements allows simultaneous achievement of power savings during holding frames and maintenance of luminance consistency.
3Reliability
If multiple switching elements with different types are used, then leakage compensation is improved, but device complexity increases
Solution Approach 1:
Different regions of the pixel circuit use switching elements with locally optimized characteristics. The first switching element is optimized for primary switching function while the second switching element is optimized for leakage compensation, allowing each component to perform its specific function efficiently.
Solution Approach 2:
The pixel circuit structure is designed to be multi-functional, where the switching elements serve multiple purposes: primary switching, leakage compensation, and adaptive operation in different driving modes. This universality reduces the need for separate dedicated components.
Data Source
AI summary
A display device includes a display panel including a pixel including switching elements of a first type and a second type different from the first type, a gate driver for generating a gate signal based on a gate clock signal and providing the gate signal to the display panel, a data driver for providing data voltage to the display panel, an emission controller for providing an emission controlling signal to the display panel, and a driving controller for generating control signals for controlling the gate and data drivers, and the emission controller. In a low-frequency driving mode, the display panel operates in a writing frame for writing data in the pixel and in a holding frame for holding the data written in the pixel, and the driving controller provides the gate driver with a gate clock signal having a direct current (DC) voltage during the holding frame.