Scan Driving Circuit Dynamic Frequency Masking Leakage
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Solution Overview
Problem
Organic light emitting display devices face issues with leakage current in transistors, affecting display quality and power consumption, particularly when the voltage level of the second driving voltage is lowered or the operation frequency is reduced.
Innovation Solution
A scan driving circuit is designed to output specific node signals and scan signals in response to clock signals and carry signals, utilizing masking circuits to manage voltage levels and frequencies, allowing for reduced power consumption by dividing the display area into regions driven at different frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If LTPS transistor is used in the circuit unit, then high mobility and stability are achieved, but leakage current is generated when voltage level is lowered or operation frequency is reduced
Solution Approach 1:
The patent applies dynamics by making the driving frequency variable rather than fixed. The display device operates at a first driving frequency during normal operation and switches to a second driving frequency (lower than the first) during power-saving mode. This dynamic frequency adjustment allows the system to reduce power consumption and minimize leakage current while maintaining display functionality, resolving the contradiction between stability and leakage current generation.
Solution Approach 2:
The patent changes the operating parameter (driving frequency) to resolve the contradiction. By switching between a first driving frequency and a second driving frequency (where the second is lower than the first), the system optimizes the balance between transistor performance and leakage current. This parameter change enables the circuit to operate efficiently at different frequency levels, reducing harmful leakage effects when high performance is not required.
2Use of energy by moving object
If operation frequency is reduced to reduce power consumption, then power consumption is lowered, but leakage current increases affecting display quality
Solution Approach 1:
The patent implements dynamic frequency switching between a first driving frequency and a second driving frequency. During power-saving operation, the system transitions to the second (lower) frequency to reduce power consumption. The masking circuit dynamically adjusts its operation based on the driving frequency, ensuring that leakage current effects are compensated for even when operating at the lower frequency, thus maintaining display quality while achieving power savings.
Solution Approach 2:
The patent employs feedback mechanisms through the masking circuit that responds to the driving frequency and signal conditions. The masking circuit adjusts its masking signals based on the operational state, providing feedback control that compensates for leakage current effects. This feedback ensures that even when operating at reduced frequency for power savings, the display quality is maintained by actively counteracting leakage current impacts.
3Use of energy by moving object
If masking circuit is used to manage voltage levels and frequencies, then power consumption is reduced, but device complexity increases
Solution Approach 1:
The masking circuit is designed to perform multiple functions: it manages voltage levels, controls frequency transitions, and compensates for leakage current effects. By integrating these functions into a single circuit block that operates across different driving frequencies, the patent reduces overall system complexity compared to having separate circuits for each function. The masking circuit serves as a multi-functional component that handles various aspects of signal management during frequency switching.
Solution Approach 2:
The masking circuit is designed to dynamically adapt its operation based on the driving frequency. It switches between different masking modes corresponding to the first and second driving frequencies, allowing it to manage power consumption effectively without requiring entirely separate static circuits for each operating mode. This dynamic adaptability reduces the need for additional complexity while maintaining power-saving capabilities.
Data Source
AI summary
A scan driving circuit includes a driving circuit which outputs a first node signal, a second node signal, and a third scan signal in response to clock signals and a carry signal, a first masking circuit which outputs a first scan signal in response to a first masking signal, the first node signal and the second node signal, and a second masking circuit which discharges the first node signal to a first voltage in response to a second masking signal and the second scan signal.