Electro-optical Device Digital Signal Control for Power Reduction
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Solution Overview
Problem
Existing organic electro-luminescence (EL) devices in head-mounted displays face challenges in achieving high-resolution, multi-grey-scale, and high-quality images at low power consumption due to variations in current-voltage characteristics and threshold voltage of transistors, which lead to increased power consumption and decreased display quality.
Innovation Solution
The electro-optical device incorporates a pixel circuit with a memory circuit, N-type and P-type transistors, and a light-emitting device, where digital signals are used to control the ratio of emission and non-emission, eliminating the need for a compensating circuit and reducing power consumption by minimizing variations in brightness and grey-scale shifts between pixels.
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 due to current flowing through the compensating circuit
Solution Approach 1:
The patent extracts and eliminates the compensating circuit from the pixel structure, replacing it with a simplified driving method that uses digital signals and a capacitive element to achieve gray-scale display without requiring additional compensation components, thereby reducing power consumption while maintaining display quality
Solution Approach 2:
The patent changes the driving parameter from analog voltage control to digital signal control, where the presence or absence of a scan signal determines whether the light-emitting element emits light, eliminating the need for compensating circuits and reducing power consumption
2Adaptability or versatility
If a large capacitive element is used to store image signals for multi-grey-scale display, then multiple grey-scales are achieved, but resolution decreases and power consumption increases due to charging and discharging requirements
Solution Approach 1:
The patent uses periodic scan signals to control the light-emitting element, where the frequency and presence of the scan signal determine the gray-scale level, enabling multi-grey-scale display without requiring a large capacitive element and maintaining high resolution
Solution Approach 2:
The patent changes from storing analog image signals in a large capacitive element to using digital scan signals that periodically control the light-emitting element, achieving multiple gray-scales through temporal control rather than spatial storage, thereby maintaining high resolution
3Adaptability or versatility
If a large capacitive element is used to store image signals, then multi-grey-scale display is achieved, but power consumption increases due to charging and discharging of the capacitive element
Solution Approach 1:
The patent employs periodic scan signals to control the light-emitting element's emission, replacing the need for continuous charging and discharging of a large capacitive element, thereby achieving multi-grey-scale display with reduced power consumption
Solution Approach 2:
The patent transitions from capacitive storage of analog signals to digital signal control, where gray-scale is achieved through the temporal pattern of scan signals rather than through capacitive charge levels, eliminating the power consumption associated with charging and discharging large capacitors
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 the display of high-resolution, multi-grey-scale images with improved uniformity and reduced power consumption, as the device operates efficiently with binary ON/OFF states of the light-emitting element, minimizing the impact of transistor variations and eliminating the need for large capacitive elements.
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 scan line, a data line, a pixel circuit provided at an intersection of the scan line and the data line, a first high potential line, a first low potential line, a second high potential line, and a second low potential line. The pixel circuit includes a light emitting device, a memory circuit disposed between the first high potential line and the first low potential line, a first transistor of N-type including a gate electrically connected to the memory circuit, and a second transistor disposed between the memory circuit and the data line. The light emitting device and the first transistor are disposed in series between the second high potential line and the second low potential line.