OLED Pixel Driving Circuit Isolating Gate from Parasitic Capacitance
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Solution Overview
Problem
Existing OLED display technology suffers from parasitic capacitance issues due to overlapping metal layers, causing crosstalk and instability in the data voltage held by the storage capacitor, which affects the display quality.
Innovation Solution
The proposed organic light emitting pixel driving circuit includes a storage capacitor unit, a coupling unit, a data writing unit, a light emitting control unit, and a reset unit, which write a compensation voltage to the second electrode and gate of the driving transistor through the coupling unit, isolating the gate from parasitic capacitance effects and maintaining stable display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the data line metal layer overlaps with the gate metal layer to share routing space, then the layout area is reduced, but parasitic capacitance is generated causing crosstalk and data voltage instability
Solution Approach 1:
The patent segments the gate control into two independent parts: the original gate electrode connected to storage capacitor C1, and a new gate electrode GOV connected to the coupling unit. This segmentation allows the gate to be controlled independently from the data line, eliminating the parasitic capacitance coupling effect while maintaining compact layout.
Solution Approach 2:
The patent introduces a coupling unit (including coupling capacitor C2 and resistor R1) as an intermediary between the data line and the gate electrode GOV. This intermediary transfers the data signal to the gate through a controlled path, isolating the gate from direct parasitic capacitance coupling with the data line while still achieving signal transmission.
2Device complexity
If the storage capacitor holds the data voltage directly at the gate, then the circuit structure is simple, but the held voltage is affected by parasitic capacitance from data line switching
Solution Approach 1:
The patent divides the gate control function into two separate electrodes: the original gate electrode for basic switching control connected to storage capacitor C1, and a new gate electrode GOV for data signal control connected to the coupling unit. This segmentation isolates the data holding function from parasitic capacitance effects.
Solution Approach 2:
The coupling unit acts as an intermediary that transfers data signals to the gate electrode GOV through capacitor C2 and resistor R1, providing a controlled signal path that is isolated from the parasitic capacitance of the data line, thereby ensuring stable data voltage.
3Manufacturing precision
If a compensation voltage is applied to the gate to correct threshold voltage variations, then the display uniformity is improved, but the parasitic capacitance still affects the compensation voltage stability
Solution Approach 1:
The patent segments the gate control into two independent electrodes, allowing the gate electrode GOV to receive compensation voltage through the coupling unit isolated from parasitic capacitance, while the original gate electrode handles basic switching. This enables stable compensation voltage application.
Solution Approach 2:
The coupling unit serves as an intermediary that protects the compensation voltage applied to gate electrode GOV from parasitic capacitance interference, ensuring that the compensation signal remains stable and effective for improving display uniformity.
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 solution effectively avoids the influence of parasitic capacitance on the gate of the driving transistor, ensuring a stable display with a wider range of data voltage signals, thereby improving display quality and reducing crosstalk.
Implementation Method 1
a storage capacitor unit connected to a gate of the driving transistor for maintaining a voltage transferred to the gate of the driving transistor
Implementation Method 2
The coupling unit is connected to a second electrode of the driving transistor... first transmitting a voltage signal change on the coupling unit to the second electrode of the driving transistor through a coupling action of the coupling unit
Implementation Method 3
a parasitic capacitance generated by a signal change on the data line Data acts on the gate of the driving transistor DT through an overlapping portion between two metal layers
Data Source
AI summary
The present application discloses an organic light emitting pixel driving circuit, an organic light emitting display panel and a driving method thereof. One embodiment of the organic light emitting pixel driving circuit comprises: a storage unit, a coupling unit, a data writing unit, a light emitting control unit, a reset unit, a data line, a first scanning line, a second scanning line, a light emitting control line, a reference voltage line, an initialization voltage line, a light emitting element and a driving transistor. By writing a compensation voltage to a second electrode of the driving transistor and then to a gate of the driving transistor through the coupling unit, the embodiment avoids a noise from a parasitic capacitance generated by a signal change on the data line to the gate of the driving transistor, therefore a stable display is achieves.