OLED Pixel Circuit with Shared Gate Signals for Aperture Ratio
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing organic light emitting diode (OLED) display devices face challenges in maintaining image quality due to electrical characteristic deviations between pixels, which require internal compensation methods, but these methods complicate the pixel structure and increase the number of control lines, making it difficult to enhance the aperture ratio and reduce the bezel width.
Innovation Solution
A display device with a reduced number of control lines is achieved by using a driving circuit that includes a capacitor connecting the source and gate of a driving TFT, along with three TFTs controlled by specific gate signals to initialize and compensate the threshold voltage and electron mobility, allowing for shared initialization signals between pixel rows to improve aperture ratio and maintain display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If three TFTs and control signals are used for initialization and data voltage application, then the electrical characteristics of pixels can be compensated, but the aperture ratio of the pixel cannot be increased
Solution Approach 1:
The patent merges the initialization signal function with the data signal function by using a single control line to carry both types of signals at different time periods. The gate driving circuit generates both initialization signals and data signals through the same control line, eliminating the need for separate control lines and reducing the number of TFTs required, thereby increasing the aperture ratio while maintaining compensation performance.
Solution Approach 2:
The patent implements dynamic signal multiplexing where the control line dynamically switches between carrying initialization signals and data signals based on timing control. The gate driving circuit dynamically generates different signal types through the same physical line, allowing flexible resource utilization and reducing static structural requirements, which increases the aperture ratio.
2Reliability
If three control lines are connected for each pixel, then the electrical characteristics can be compensated, but it is difficult to raise the aperture ratio
Solution Approach 1:
The patent makes the control line universal by enabling it to perform multiple functions: carrying initialization signals during initialization periods and data signals during data writing periods. This multi-functionality eliminates the need for separate dedicated control lines for different signal types, reducing the total number of control lines from three to one while maintaining full compensation capability.
Solution Approach 2:
The patent combines multiple control functions into a single control line. Instead of having separate lines for initialization control and data control, the invention merges these functions into one line that sequentially carries different signal types, thereby reducing device complexity and the number of required control lines.
3Adaptability or versatility
If GIP circuit is implemented in the display panel, then the gate driving function is integrated, but the size of the GIP circuit becomes larger and the bezel width increases
Solution Approach 1:
The patent extracts and removes unnecessary circuit elements from the GIP circuit structure. By eliminating the need for multiple control lines and associated TFTs through signal multiplexing, the physical area required for the gate driving circuit is reduced, allowing for a smaller bezel width while maintaining integration benefits.
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A display device includes a plurality of pixels, and a pixel disposed in a n-th pixel line has a light emitting diode, a driving TFT to control a current flowing the light emitting diode, a capacitor connecting a source of the driving TFT and a gate of the driving TFT, a first TFT controlled by a first gate signal which is transferred through a first gate line to connect the gate of the driving TFT to one of data lines, a second TFT controlled by a second gate signal which is transferred through a second gate line to connect the gate of the driving TFT to an initialization voltage, and a third TFT controlled by the second gate signal transferred to a pixel disposed in a (n-1)-th pixel line to connect the source of the driving TFT to a reference voltage, n being a natural number.