OLED Pixel Circuit With Fifth Transistor for Frequency-Stable Luminance
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Solution Overview
Problem
Display devices face challenges in reducing power consumption while maintaining display quality, especially as operating frequency changes, leading to potential deterioration in display quality.
Innovation Solution
The display device incorporates a specific configuration of transistors and capacitors connected to a light emitting diode, with distinct scan, initialization, compensation, and black periods, allowing for independent control of voltage applications to minimize luminance differences across frequencies, thereby preventing display quality deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the operating frequency is decreased to reduce power consumption, then power consumption is reduced, but display quality deteriorates
Solution Approach 1:
The patent applies preliminary action by performing initialization and compensation operations before the main data writing operation. The initialization period sets up the pixel circuit state, and the compensation period adjusts for threshold voltage variations, ensuring that when data is written at lower frequencies, the pixel can still achieve accurate luminance levels. This preliminary preparation allows the system to operate at reduced frequencies while maintaining display quality.
Solution Approach 2:
The patent segments the pixel driving cycle into distinct time periods: initialization period, compensation period, black period, and write period. Each period serves a specific function in preparing the pixel circuit for accurate operation. By segmenting the process, the system can allocate sufficient time for each operation even at lower operating frequencies, preventing display quality deterioration while reducing overall power consumption.
2Reliability
If multiple transistor configurations are added to maintain display quality at different frequencies, then display quality is maintained, but device complexity increases
Solution Approach 1:
The patent implements multi-functionality by designing the pixel circuit with transistors that serve multiple purposes across different operating conditions. The same transistor configuration used for initialization also supports compensation and data writing operations. The first and second transistors work together to provide both initialization and data driving functions, reducing the need for separate dedicated circuits for each function and thereby limiting the increase in device complexity.
Solution Approach 2:
The patent applies dynamics by making the transistor operation time-varying through different control signals (scan signals, data signals, compensation signals). The transistors are dynamically switched between different operational states depending on the current phase of the driving cycle. This dynamic operation allows a fixed hardware configuration to adapt to different operating frequencies and modes without requiring additional physical components, thus maintaining display quality while controlling device complexity.
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 effectively reduces luminance differences at various operating frequencies, ensuring consistent display quality and preventing deterioration, even at higher frequencies.
Implementation Method 1
at least one of the pixels includes a light emitting diode
Data Source
AI summary
A display device includes a display panel including a plurality of pixels. At least one of the pixel includes a light emitting diode, a first transistor connected between a power line receiving a power source voltage and an anode of the light emitting diode, a second transistor connected between a data line and a first reference node, a first capacitor connected between the power line and the first reference node, a second capacitor connected between the first reference node and a second reference node, a third transistor connected between the first refence node and a reference voltage line receiving a reference voltage, a fourth transistor connected between an initialization voltage line receiving an initialization voltage and a drain of the first transistor, and a fifth transistor connected between the drain of the first transistor and the anode of the light emitting diode.