Pixel Circuit Bias Switching for Brightness at Variable Refresh Rates
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Solution Overview
Problem
Existing display apparatuses face challenges in achieving improved display quality and efficiency, particularly in managing pixel operations to enhance brightness control and reduce power consumption.
Innovation Solution
A pixel structure is implemented with multiple transistors and capacitors, including a fifth transistor that supplies bias voltages to a third node, and a gate-on voltage sequence to control light emission during different scan periods, allowing for variable refresh rates and improved brightness maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple transistors are added to control current and bias voltages during different scan periods, then display quality and brightness consistency are improved, but device complexity increases
Solution Approach 1:
The pixel circuit is divided into functional modules with specific transistors for different operations: first and second transistors control current during first scan period, third and fourth transistors control current during second scan period, and fifth transistor provides bias voltage. This segmentation allows independent optimization of brightness control for different scan periods without requiring a completely redesigned circuit.
Solution Approach 2:
The circuit dynamically switches between different transistor configurations based on scan period. During first scan period, first and second transistors are active; during second scan period, third and fourth transistors become active. This dynamic reconfiguration enables the circuit to adapt to different operational requirements and maintain brightness consistency across varying conditions.
2Productivity
If gate voltage control signals are applied during different scan periods, then light emission efficiency is improved, but control complexity increases
Solution Approach 1:
The gate voltage control operates in periodic cycles corresponding to scan periods. During first scan period, specific gate voltages are applied to first and second transistors; during second scan period, different gate voltages are applied to third and fourth transistors. This periodic control pattern optimizes light emission efficiency for each period while maintaining a manageable control structure through repetition.
Solution Approach 2:
The light emission function is maintained continuously across both scan periods through appropriate transistor switching. The fifth transistor provides continuous bias voltage to ensure proper operation. By ensuring that at least one transistor configuration is active during each scan period, the system maintains continuous light emission without interruption, improving overall efficiency.
3Duration of action of stationary object
If bias voltage is supplied during both scan periods, then light-emitting device lifespan is extended, but energy consumption increases
Solution Approach 1:
The fifth transistor provides bias voltage selectively to specific nodes (third node and fourth node) during specific scan periods rather than uniformly across the entire circuit continuously. This localized voltage application ensures proper biasing for lifespan extension while minimizing unnecessary energy consumption in other parts of the circuit during other periods.
Solution Approach 2:
The bias voltage supplied by the fifth transistor is adjusted according to the scan period. Different bias voltage levels are applied during first and second scan periods to optimize both device protection and energy efficiency. This parameter adjustment allows the system to extend device lifespan through proper biasing while controlling energy consumption by avoiding excessive voltage application when not needed.
Data Source
AI summary
A pixel includes a first transistor to output a current supplied to a light-emitting device, a second transistor electrically connected between a gate of the first transistor and a first terminal of the first transistor, a third transistor electrically connected between the first voltage line and a second terminal of the first transistor, a fourth transistor electrically connected between the first terminal of the first transistor and the light-emitting device, and a fifth transistor configured to supply a bias voltage to the second terminal of the first transistor. A gate-on voltage may be supplied to a gate of the fifth transistor during a portion of a period during which a gate-off voltage may be supplied to a gate of the third transistor and a gate of the fourth transistor.