OLED Pixel Circuit Capacitor Integration for Reduced Complexity
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Solution Overview
Problem
Existing electro-optical devices using OLED elements require large capacitance values for sufficient light emission, leading to increased complexity and capacitance requirements in each unit circuit.
Innovation Solution
The electro-optical device employs a configuration where electric charges are charged in a capacitor element during a write period and supplied to the OLED element during a drive period, allowing for sufficient light emission with reduced capacitance needs, and optionally uses an auxiliary capacitor to supplement capacitance and control light emission levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the capacitance of the capacitor element Co is increased to acquire sufficient light emission from the OLED element, then the light emission amount is improved, but the device complexity and circuit design difficulty increase
Solution Approach 1:
The patent merges the capacitor element Co with the pixel circuit by connecting the capacitor to the data line, allowing the data line to serve dual purposes as both a data transmission line and a charging path for the capacitor. This integration reduces the need for separate high-capacitance components while maintaining sufficient light emission from the OLED element.
Solution Approach 2:
The capacitor element Co is charged during the write period before the display period begins. By pre-charging the capacitor with the required electric charge during the write period, the OLED element receives sufficient charge during the subsequent display period to maintain light emission without requiring the capacitor to have very large capacitance value.
2Duration of action of moving object
If the capacitance of the capacitor element Co is set to a very large value to maintain light emission, then the light emitting time is extended, but the unit circuit size and complexity increase
Solution Approach 1:
The capacitor element is integrated into the pixel circuit structure with shared connections to the data line and OLED element. This merging allows the capacitor to maintain adequate charge for the required light emitting duration without occupying excessive circuit area, as it shares routing resources with other circuit elements.
Solution Approach 2:
The patent changes the operational parameters by separating the write period (for charging) from the display period (for light emission). By controlling the timing and duration of these periods, the system achieves sufficient light emitting time with a capacitor of moderate capacitance value, rather than requiring very large capacitance.
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 configuration achieves sufficient light emission with decreased capacitance requirements, simplifies the device structure, and allows for controlled light emission levels, enhancing the efficiency and precision of the electro-optical device.
Implementation Method 1
a capacitor element Co. The gate of the transistor Ts is connected to the scanning line. In addition, as shown in FIG. 29, the OLED element and the capacitor element Co are connected in parallel
Implementation Method 2
various image display devices using electro-optical elements such as organic light emitting diode elements (hereinafter referred to as OLED) referred to as organic EL (Electroluminescent) elements
Data Source
AI summary
An electro-optical device includes a plurality of unit circuits that are disposed in correspondence with intersections of a plurality of scanning lines and a plurality of data lines, a scanning line driving circuit that sequentially selects the plurality of scanning lines, one scanning line being selected for a drive period of one unit period, and a data line driving circuit that outputs data electric potentials to the plurality of data lines for a write period of the one unit period, the data electric potentials corresponding to gray scale data of the plurality of unit circuits that are in correspondence with the one scanning line selected for the drive period of the one unit period and the write period being a period before the each drive period starts. Each of the plurality of unit circuits has an electro-optical element that has a gray scale level corresponding to the data electric potential, a capacitor element that has a first electrode connected to a capacitor line and a second electrode connected to the data line, and a switching element that is disposed between the second electrode and the electro-optical element and is in a conductive state at a time when the one scanning line is selected by the scanning line driving circuit for making the second electrode and the electro-optical element to be conductive to each other.