OLED Pixel Circuit Overlapping Scan and Emission Periods
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As OLED display panels increase in size and resolution, the time required for image data programming becomes more challenging, especially when displaying stereoscopic images, which demands higher driving frequencies and complicates the operation of display devices.
Innovation Solution
The proposed solution involves a pixel structure with multiple transistors and capacitors that allow for simultaneous data writing and light emission, utilizing a switching transistor, driving transistor, reference voltage transistor, initialization transistor, and compensation transistor to manage voltages and currents efficiently, enabling overlapped scan and light emission periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the display panel size and resolution are increased, then the display quality is improved, but the time required for image data programming increases and driving becomes more difficult
Solution Approach 1:
The patent applies preliminary action by performing data programming during the light emission period of the previous frame. The pixel circuit stores image data in advance using capacitors (ELVDD capacitor and emission voltage capacitor) so that data is ready before the actual light emission period begins. This allows the display to maintain high resolution and quality while reducing the critical programming time window.
2Productivity
If the driving frequency is increased for stereoscopic image display, then the display performance is improved, but the operation complexity of the display device increases
Solution Approach 1:
The patent merges the scan period and light emission period to overlap in time. The emission voltage generation circuit combines multiple functions (voltage generation, storage, and control) into a single integrated circuit per pixel. This consolidation reduces operation complexity by providing unified control signals while maintaining the high driving frequency needed for stereoscopic display at 240Hz or higher.
Solution Approach 2:
The emission voltage generation circuit serves multiple functions: generating emission voltage, storing it in capacitors, controlling light emission timing, and maintaining voltage levels throughout the light emission period. This multi-functionality reduces the number of separate components needed, simplifying the overall device operation while supporting high-frequency stereoscopic display.
3Use of energy by moving object
If the aperture ratio is increased, then the light emission efficiency is improved, but the area available for transistor and capacitor placement is reduced
Solution Approach 1:
The pixel circuit is segmented into functional modules: data programming circuit, emission voltage generation circuit, and light emission control circuit. Each module uses capacitors strategically placed to store voltages during specific periods. The ELVDD capacitor stores voltage during the scan period, while the emission voltage capacitor stores voltage during the light emission period. This segmentation allows efficient use of available area while maintaining high aperture ratio for better light emission efficiency.
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 approach stabilizes the enlargement of high-resolution display panels, improves stereoscopic image display quality, and enhances the aperture ratio, ensuring sufficient data writing time and efficient operation.
Implementation Method 1
an organic light emitting material emitting light by the electric field
Data Source
AI summary
An organic light emitting diode (OLED) display device includes a plurality of OLED pixels. In one aspect, each pixel respectively includes a first capacitor connected between a data line and a first node, a switching transistor connecting the first node and a second node, a second capacitor connected between the second node and a third node, a driving transistor having a gate electrode connected to the third node and controlling a driving current flowing from a first power source voltage to an OLED, and a reference voltage transistor transmitting a reference voltage to the first node. When a light emitting step occurs in which the OLED emits light, it is simultaneously performed in a plurality of pixels by use of a driving current, the switching transistor is turned off and the reference voltage transistor is turned on such that the reference voltage is transmitted to the first node, and a data voltage corresponding to a scan signal of a gate-on voltage respectively corresponding to a plurality of pixels is stored to the first capacitor. Aspects also include pixel circuits and methods of driving the pixels in the display.