Electro-Optical Pixel Circuit Memory for Low Power Display
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Solution Overview
Problem
Existing organic electro-luminescence (EL) devices in head-mounted displays face challenges in achieving high resolution, multiple gray scales, and low power consumption due to variations in current-voltage characteristics and threshold voltage of drive transistors, which affect display quality and increase power consumption.
Innovation Solution
The electro-optical device incorporates a pixel circuit with a memory circuit including inverters and transistors, allowing digital image signal writing and controlling the light-emitting element's emission ratio, minimizing transistor variations and eliminating the need for a compensating circuit, thus reducing power consumption and enabling finer pixels without large capacitive elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a compensating circuit is provided to compensate for variations in current-voltage characteristics and threshold voltage of drive transistor, then display quality is improved, but power consumption increases
Solution Approach 1:
The patent extracts and eliminates the compensating circuit from the pixel structure, replacing it with a simplified drive circuit that uses digital signaling and a memory element. This removal of the compensating circuit directly reduces power consumption while maintaining display quality through alternative means (digital gray scale control and transistor state memory).
Solution Approach 2:
The patent changes the operating parameters of the drive circuit from analog continuous control to digital discrete states (ON/OFF states of transistors). By using digital gray scale values stored in the memory element, the system achieves compensation for transistor variations without the continuous current control that caused high power consumption in traditional compensating circuits.
2Adaptability or versatility
If the electric capacitance of capacitive element is increased to achieve more gray-scales of display, then gray-scale display capability is improved, but power consumption increases due to charging and discharging
Solution Approach 1:
The patent implements gray-scale display through periodic time-multiplexed control, where digital gray scale values are written to the memory element during specific time periods and then maintained without continuous charging/discharging. This periodic writing approach eliminates the continuous power consumption associated with maintaining large capacitor charges for gray-scale control.
Solution Approach 2:
The patent replaces the capacitive storage mechanism with a transistor-based memory circuit that uses regenerative feedback loops (inverters) to maintain digital states. This substitution eliminates the need for large capacitive elements and their associated charging/discharging power consumption while preserving gray-scale display capability through digital state retention.
3Adaptability or versatility
If the electric capacitance of capacitive element is increased to achieve more gray-scales of display, then gray-scale display capability is improved, but pixel size increases reducing resolution
Solution Approach 1:
The patent replaces the capacitive storage mechanism with a transistor-based memory circuit using inverters and feedback loops. This substitution eliminates the need for large physical capacitors, thereby reducing pixel area and enabling higher resolution displays while maintaining multi-gray-scale capability through digital state storage.
Solution Approach 2:
The memory circuit elements (inverters and transistors) serve multiple functions: they store digital gray scale values, maintain transistor states, and provide regenerative feedback for state retention. This multi-functionality eliminates the need for dedicated large capacitive elements, allowing smaller pixel sizes for high resolution while preserving gray-scale display capability.
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 enables high-resolution, multi-gray-scale, and high-quality image display at low power consumption by minimizing transistor variations and eliminating the need for large capacitive elements, improving display quality and reducing power usage.
Implementation Method 1
an organic EL device that includes an organic EL element as a light-emitting element
Data Source
AI summary
An electro-optical device includes a pixel circuit provided to correspond to an intersection of a scan line and a data line, a low potential line, and a high potential line. The pixel circuit includes a light emitting element, a first transistor, and a memory circuit including a first inverter, a second inverter, and a second transistor. The first transistor is disposed between an first input terminal of the first inverter and the data line. The second transistor is disposed between an second output terminal of the second inverter and the first input terminal. An first output terminal of the first inverter is electrically connected to an second input terminal of the second inverter. When the first transistor is in an ON-state, the second transistor is in an OFF-state.