Alternating OLED Drive Pixel Circuit for Lifetime Extension
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Solution Overview
Problem
The long-term application of organic light-emitting displays, particularly large size and high brightness AMOLEDs, is limited by the degradation of OLEDs due to continuous DC driving, which increases threshold voltage and decreases light-emitting efficiency, leading to shorter lifetimes.
Innovation Solution
A pixel circuit design featuring a charging sub-circuit, two driving sub-circuits with opposite current flow directions, and capacitors to alternate the driving of two light-emitting devices using N-type and P-type transistors, allowing each device to emit light in different periods, thereby reducing the impact of continuous DC voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous DC driving voltage is applied to the light emitting device, then the light emitting device can maintain stable operation, but the threshold voltage increases and light-emitting efficiency decreases dramatically
Solution Approach 1:
The patent implements periodic action by alternating the driving of two light emitting devices (OLED1 and OLED2) in different time periods. During the first time period, OLED1 is driven while OLED2 is in standby; during the second time period, OLED2 is driven while OLED1 is in standby. This periodic switching prevents continuous DC driving of a single device, thereby avoiding threshold voltage increase and maintaining light-emitting efficiency.
2Reliability
If continuous DC driving voltage is applied to the light emitting device, then the light emitting device can maintain stable operation, but the lifetime of the light emitting device is shortened
Solution Approach 1:
The patent applies periodic action by implementing time-division multiplexed driving of two light emitting devices. Each device is driven for a specific time period and then placed in standby for an equal time period. This periodic operation pattern prevents continuous DC driving stress on any single device, thereby extending the operational lifetime of the light emitting devices.
Solution Approach 2:
The patent implements discarding and recovering by alternating the active and standby states of the light emitting devices. When OLED1 is driven, OLED2 is in standby (discarded from active operation); when OLED2 is driven, OLED1 is in standby. This cycling allows each device to be recovered from continuous operation stress, extending their operational lifetime.
3Device complexity
If a single light emitting device is driven in each pixel unit, then the pixel circuit structure is simple, but the lifetime of the light emitting device is limited due to continuous DC driving
Solution Approach 1:
The patent applies segmentation by dividing each pixel unit into two separate light emitting devices (OLED1 and OLED2) that can be independently controlled. This segmentation allows the pixel circuit to switch between driving different devices, preventing continuous DC driving of a single device and thereby extending its lifetime while maintaining manageable circuit complexity.
Solution Approach 2:
The patent implements periodic action within the pixel circuit by alternating the driving of OLED1 and OLED2 in different time periods. This periodic switching mechanism extends the lifetime of individual devices while maintaining a relatively simple pixel circuit structure that uses standard transistor components.
4Duration of action of stationary object
If two light emitting devices are driven alternately, then the lifetime of light emitting devices is extended, but the pixel circuit structure becomes more complex
Solution Approach 1:
The patent applies universality by designing the pixel circuit so that the same transistor components (T1, T2, C1, C2) serve multiple functions: they control both OLED1 and OLED2, manage charging and discharging operations, and enable time-division multiplexed driving. This multi-functionality extends device lifetime while minimizing the increase in circuit complexity.
Solution Approach 2:
The patent merges the control functions for two light emitting devices into a single pixel circuit structure. The transistors and capacitors are shared and configured to handle both devices alternately, combining what could have been two separate control circuits into one integrated unit, thereby extending lifetime with minimal complexity increase.
Data Source
AI summary
A pixel circuit, a display panel and a display apparatus are used to improve the lifetime of the light emitting devices in the display apparatus. The pixel circuit comprises: a charging sub-circuit (1), a first driving sub-circuit (2), a second driving sub-circuit (3), a first capacitor (C1) and a second capacitor (C2). A first terminal (A) of the first capacitor (C1) is connected to a first terminal of the first driving sub-circuit (2) and a first terminal of the second driving sub-circuit (3), and a second terminal (B) of the first capacitor (C1) is connected to the charging sub-circuit (1) and a first terminal (C) of the second capacitor; a second terminal of the first driving sub-circuit (2) is connected to a first light emitting device (D1), a second terminal of the second driving sub-circuit (3) is connected to a second light emitting device (D2), wherein the driving current flowing from the first driving sub-circuit (2) to the first light emitting device (D1) is in an opposite direction to the driving current flowing from the second driving sub-circuit (3) to the second light emitting device (D2).