Pixel Driving Circuit Timing for Low-Power Display Quality
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Solution Overview
Problem
There is a need for technology that reduces power consumption in display devices while maintaining high display quality, particularly in battery-operated portable devices, as existing methods to lower operating frequency can degrade display quality.
Innovation Solution
A pixel driving circuit is introduced that includes specific transistors and capacitors configured to manage scan and emission control signals, with controlled active and non-active periods, to optimize power consumption and maintain display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the operating frequency is lowered to reduce power consumption, then power consumption decreases, but display quality may deteriorate
Solution Approach 1:
The frame period is divided into distinct driving period and scan period, allowing different operational modes. During scan period, the light emitting transistor is turned off to reduce power consumption, while during driving period, normal operation resumes to maintain display quality. This temporal segmentation enables low power consumption without sacrificing display performance.
Solution Approach 2:
The emission control signal operates periodically with active and non-active periods. During the non-active period (scan period), the light emitting transistor is turned off to reduce power consumption. During the active period (driving period), the transistor operates normally to maintain display quality. This periodic switching achieves low power consumption while preserving display performance.
2Use of energy by moving object
If the operating frequency is lowered to reduce power consumption, then power consumption decreases, but brightness consistency may deteriorate
Solution Approach 1:
During the scan period, the initialization transistor resets the pixel circuit to a known state before the next driving period begins. This preliminary initialization ensures that when the light emitting transistor turns on in the driving period, the pixel is properly prepared, maintaining brightness consistency even at lower operating frequencies.
Solution Approach 2:
The capacitor stores the gate-source voltage of the driving transistor during the scan period, preserving the brightness information. When the driving period begins, this stored voltage is restored, ensuring brightness consistency is maintained across frame transitions and during low power consumption modes.
3Reliability
If scan signals are applied during the scan period to initialize pixels, then display quality is maintained, but power consumption increases
Solution Approach 1:
The initialization operation is performed locally at the pixel level during the scan period when the light emitting transistor is off. The initialization transistor selectively resets only the necessary pixel circuits, maintaining display quality without requiring full-power operation across the entire display, thus reducing overall power consumption.
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
The pixel driving circuit effectively reduces power consumption while preventing degradation of display quality by optimizing signal timing and transistor states, ensuring efficient operation and image clarity.
Implementation Method 1
a first capacitor connected between the first node and the second node
Implementation Method 2
a light emitting diode and a pixel driving circuit connected to the light emitting diode
Data Source
AI summary
A display device including: a pixel driving circuit that includes: a first transistor including a gate electrode connected to a first node, a first electrode connected to a first voltage, and a second electrode connected to a second node; a second transistor including a gate electrode connected to a first scan line, a first electrode connected to a data line, and a second electrode connected to the first node; a sixth transistor including a gate electrode connected to a second emission line, a first electrode connected to the second node, and a second electrode connected to a third node; and a fourth transistor including a gate electrode connected to a second scan line, a first electrode connected to the third node, and a second electrode connected to a second voltage, and a non-active period of the second emission control signal overlaps an active period of the second scan signal.