OLED Pixel Circuit Carrier Release Sub-circuit Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Organic light-emitting diode (OLED) display devices experience a significant decrease in light-emitting efficiency over time, leading to deterioration in picture quality, which is exacerbated by increased driving voltage attempts to delay this decline, but also reduces the service life of the devices.
Innovation Solution
A pixel circuit comprising a light-emitting element, a driving sub-circuit, a scanning sub-circuit, and a carrier releasing sub-circuit, where the driving sub-circuit controls current through the light-emitting element based on stored voltage, the scanning sub-circuit updates this voltage, and the carrier releasing sub-circuit applies a reverse bias voltage to the light-emitting element during specific scanning signal periods, periodically setting it to a reverse bias state to release accumulated carriers and prevent electric field buildup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If driving voltage is increased to delay light-emitting efficiency decline, then light-emitting efficiency is maintained, but service life is reduced
Solution Approach 1:
The patent implements periodic switching between forward bias state (for normal light emission) and reverse bias state (for carrier release) through the bias voltage control circuit. During the reverse bias period, accumulated carriers are released from the light-emitting element, preventing efficiency degradation. This periodic maintenance action allows the element to operate at optimal efficiency without requiring continuously increased driving voltage, thereby extending service life while maintaining illumination performance.
2Illumination intensity
If carrier releasing sub-circuit is added to release accumulated carriers, then light-emitting efficiency is maintained, but device complexity is increased
Solution Approach 1:
The bias voltage control circuit serves multiple functions: it provides forward bias voltage during normal operation, switches to reverse bias voltage for carrier release, and controls the timing of these transitions. By making this single circuit multi-functional, the patent avoids adding separate dedicated carrier releasing circuits, thus maintaining light-emitting efficiency while minimizing the increase in device complexity.
Solution Approach 2:
The patent combines the carrier release function with the existing bias voltage control circuitry. The same circuit that controls the bias voltage for normal operation is also used to apply reverse bias for carrier release by simply changing the voltage polarity and timing. This merging of functions reduces the overall circuit complexity compared to having separate independent circuits for bias control and carrier release.
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
This configuration delays the decrease in light-emitting efficiency, prolongs the life of the light-emitting element, and reduces the deterioration of OLED display devices by periodically releasing carriers and mitigating the impact of built-in electric fields.
Implementation Method 1
the carrier releasing sub-circuit is configured to provide a reverse bias voltage to the second electrode of the light-emitting element during an effective period of a second scanning signal
Data Source
AI summary
Provided are a pixel circuit and driving method thereof, array substrate and display device. The pixel circuit includes a light-emitting element, a driving sub-circuit, a scanning sub-circuit, and a carrier releasing sub-circuit. The driving sub-circuit is connected to a first electrode of light-emitting element, and the driving sub-circuit is configured to store a driving voltage and control the magnitude of a current passing through light-emitting element according to the driving voltage; the scanning sub-circuit is connected to driving sub-circuit. The scanning sub-circuit is configured to update the driving voltage stored by driving sub-circuit during the effective period of first scanning signal; the carrier releasing sub-circuit is connected to a second electrode of light-emitting element, and provides a reverse bias voltage to the second electrode of light-emitting element during the effective period of second scanning signal, thereby delaying the decrease of light-emitting efficiency of light-emitting element along with the service time.