OLED Pixel Circuit Short-Circuit Protection Mechanism
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Solution Overview
Problem
In OLED displays, short circuits between the cathode and anode can lead to malfunctioning pixels, causing display quality issues and requiring complex and inefficient methods for correction, such as laser ablation.
Innovation Solution
A pixel circuit with a short-circuit protection circuit that automatically detects input terminal signals and disconnects or connects the light emitting circuit branch, using a short circuit protection transistor and signal control circuit to prevent damage from short circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a short circuit occurs between the cathode and anode of the OLED device, then a large current is generated at the malfunctioned pixel, but the light emitting state of pixels around the malfunctioned pixel is affected
Solution Approach 1:
The patent implements preliminary detection of short circuits in OLED pixels before they cause damage to surrounding pixels. The detection circuit monitors the voltage at the anode of each OLED pixel, and when a short circuit is detected (voltage drops below a threshold), the system immediately isolates the malfunctioned pixel by turning off the corresponding pixel circuit. This preliminary action prevents the large current from affecting neighboring pixels, thereby maintaining overall display quality.
2Reliability
If the malfunctioned pixel is removed by laser ablation, then the large current is suppressed, but the process becomes complicated and difficult to remedy for new malfunctioned pixels
Solution Approach 1:
The patent implements a self-service mechanism where the pixel circuit automatically detects and isolates its own malfunction without requiring external intervention. The detection circuit monitors each pixel's voltage, and when a short circuit is detected, the pixel circuit automatically turns off the OLED pixel and isolates it from the power supply. This self-service approach eliminates the need for complex external processes like laser ablation, simplifying the handling process while maintaining reliable current suppression.
Solution Approach 2:
The patent implements a feedback mechanism where the voltage signal from the anode of each OLED pixel is continuously monitored by the detection circuit. When the voltage drops below a threshold indicating a short circuit, the feedback signal triggers the pixel circuit to turn off the OLED pixel and isolate it. This closed-loop feedback system enables automatic detection and response to malfunctioned pixels, eliminating the need for manual or complex external intervention.
3Manufacturing precision
If the functional structure film layers are made thinner to reduce resistance, then the manufacturing precision is improved, but the risk of short circuit between cathode and anode increases
Solution Approach 1:
The patent implements preliminary detection and isolation mechanisms that compensate for the increased short circuit risk associated with thinner film layers. The detection circuit continuously monitors the voltage at the anode of each OLED pixel, and when a short circuit is detected (voltage drops below a threshold), the system immediately isolates the malfunctioned pixel by turning off the corresponding pixel circuit. This preliminary action prevents the spread of short circuits, enabling the use of thinner film layers for improved manufacturing precision while maintaining overall device reliability.
Data Source
AI summary
A pixel circuit and a driving method thereof, a display panel. The pixel circuit includes a driving circuit, a light emitting circuit and a short-circuit protection circuit. The short-circuit protection circuit is connected in series between the driving circuit and the light emitting circuit, and the short-circuit protection circuit is configured to obtain an input terminal signal of the light emitting circuit and disconnect or connect an input signal branch of the light emitting circuit according to the obtained input terminal signal of the light emitting circuit.