Pixel Circuit Reverse-Bias Burnout for OLED Dark Spots
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Solution Overview
Problem
The transparent cathode sputter process in manufacturing top-emission light-emitting devices leads to particle generation between the anode and cathode, causing dark spots in the display product.
Innovation Solution
A pixel circuit design with a driving circuit, control circuit, and light-emitting module, including transistors with specific width-to-length ratios and additional circuits for energy storage and data writing, allows for controlled application of forward or reverse voltages to burn out particles at dark spots, enhancing product yield and display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If transparent cathode sputter process is used to manufacture top-emission light-emitting device, then light emission function is achieved, but particles are generated between anode and cathode causing dark spots
Solution Approach 1:
The patent applies reverse voltage to the light-emitting element to burn out particles trapped between the anode and cathode. By utilizing electrical stress in the form of reverse bias, the harmful particles are vaporized or removed, converting the manufacturing defect into a recoverable condition and restoring normal light emission.
Solution Approach 2:
The patent changes the voltage parameter by applying reverse voltage (negative bias) to the light-emitting element after particle contamination occurs during sputtering. This parameter change enables the burning out of particles and restoration of display quality without requiring remanufacturing.
2Reliability
If pixel circuit is designed with control circuit and energy storage circuit, then dark spots can be corrected by applying reverse voltage, but device complexity increases
Solution Approach 1:
The control circuit and energy storage circuit are integrated into the existing pixel circuit structure, allowing the same circuit components to serve dual functions: normal driving operation and dark spot correction. The energy storage capacitor stores energy for both driving the light-emitting element and providing reverse voltage for particle removal, eliminating the need for separate dedicated correction circuits.
3Object-affected harmful factors
If branch current is increased to burn out particles, then dark spots are eliminated, but tolerance to current limitations is reduced
Solution Approach 1:
The patent applies reverse voltage in a periodic or pulsed manner rather than continuously. The energy storage capacitor charges during normal operation and discharges in controlled pulses to burn out particles. This periodic action achieves particle removal while limiting the duration and total energy exposure, thereby protecting the light-emitting element from excessive current damage.
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 circuit effectively addresses dark spots by increasing branch current and tolerance to current limitations, improving product yield and display quality by converting dark spots into normal pixels.
Implementation Method 1
burn out particles at dark spots
Data Source
AI summary
Pixel circuit, driving control method, display substrate and device are disclosed. The pixel circuit includes a driving circuit, a control circuit and a light-emitting module; the driving circuit generates driving current for driving the light-emitting module under control of control end of the driving circuit; the control circuit is connected to first scanning line, power supply voltage line and second end of the driving circuit, and controls connection between the power supply voltage line and the second end of the driving circuit under control of first scanning signal; second end of the light-emitting module is connected to a cathode voltage line. With the control circuit, branch current can be increased by increasing forward and reverse voltages, such that foreign bodies at dark spots can be burnt out and the dark spots can be changed into normal pixels, thereby improving product yield and displaying quality.