Intermediate-Node Hold Capacitor for Low-Frequency Display Driving
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Solution Overview
Problem
Low-frequency driving methods in display devices lead to increased pixel luminance differences between consecutive frames due to leakage currents, which are not effectively addressed by existing technologies.
Innovation Solution
A display device design incorporating a specific configuration of switching elements and capacitors, including a hold capacitor to compensate for kickback voltages at intermediate nodes, reducing leakage currents by increasing the capacity of the hold capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If low-frequency driving method is used, then power consumption is reduced, but leakage current increases causing pixel luminance difference
Solution Approach 1:
The hold capacitor is charged in advance during the programming phase before the low-frequency driving begins. This preliminary charging action ensures that the capacitor can compensate for leakage currents that occur during subsequent low-frequency operation, maintaining pixel luminance uniformity without increasing power consumption.
Solution Approach 2:
The hold capacitor acts as an intermediary energy storage element between the programming phase and the low-frequency driving phase. It stores the voltage level needed for proper pixel operation and releases it to compensate for leakage currents during low-frequency driving, thereby maintaining luminance uniformity while preserving the low power consumption benefit.
2Reliability
If hold capacitor capacity is increased to reduce leakage current, then pixel luminance uniformity improves, but device complexity increases
Solution Approach 1:
The hold capacitor is merged with the existing pixel circuit structure, sharing the same physical space and manufacturing process. The capacitor is formed using the same thin film deposition and patterning steps as the transistor gates, eliminating the need for separate capacitor fabrication processes and reducing overall device complexity despite the added functionality.
Solution Approach 2:
The hold capacitor serves multiple functions: it stores voltage during the programming phase, compensates for leakage currents during low-frequency driving, and maintains pixel luminance uniformity. This multi-functionality reduces the need for additional separate components, thereby reducing device complexity while improving reliability.
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 proposed design effectively reduces leakage currents and kickback voltages, thereby minimizing pixel luminance differences and improving display quality at low frequencies.
Implementation Method 1
a capacitor including a first electrode configured to receive a power voltage, and a second electrode connected to the first intermediate node and to the second intermediate node
Data Source
AI summary
A display device includes a light-emitting element, a driving element to apply a driving current, a 1-1 switching element including a first electrode connected to a gate electrode of the driving element, a gate electrode, and a second electrode connected to a first intermediate node, a 1-2 switching element including a first electrode connected to the first intermediate node, a gate electrode, and a second electrode connected to a second electrode of the driving element, a 2-1 switching element including a first electrode connected to a second intermediate node, a gate electrode, and a second electrode connected to the gate electrode of the driving element, a 2-2 switching element including a first electrode, a gate electrode, and a second electrode connected to the second intermediate node, and a capacitor including a first electrode to receive a power voltage, and a second electrode connected to the first and second intermediate nodes.