Display Subfield Arrangement for AC-Driven Light Source Luminance
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Solution Overview
Problem
AC-driven light sources in display panels cause adverse effects on gradation representation due to varying luminance, even with subfields of the same period, leading to inconsistent transmittance or reflectance when pixels are turned on or off.
Innovation Solution
An image display apparatus with a control unit that arranges subfields to maintain a predetermined relationship with the light-source driving circuit, ensuring gradation representation is not affected by luminance changes, by setting the transmittance or reflectance of pixels based on gray levels and using an adjusting subfield to maintain uniform initial states for improved gradation representation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If the light source is AC-driven to achieve long life, then the light source lifespan is improved, but the luminance varies causing adverse effects on gradation representation
Solution Approach 1:
The patent applies dynamics by making the subfield arrangement adaptive to the AC-driven light source's luminance variations. Instead of using fixed-period subfields, the system dynamically adjusts subfield timing to maintain consistent gradation representation despite the light source's periodic luminance changes, thus resolving the contradiction between long-life AC operation and gradation accuracy
Solution Approach 2:
The patent changes the temporal parameters of subfields (timing and duration) to compensate for light source luminance variations. By adjusting when subfields occur within the frame and their relative durations, the system maintains accurate gradation representation even as the light source undergoes periodic luminance changes during AC operation
2Device complexity
If subfields of the same period are used for representing gradation, then the structure is simplified, but the varying luminance causes inconsistent transmittance or reflectance
Solution Approach 1:
The patent transitions from static equal-period subfields to dynamic subfields with adjusted timing and duration. This dynamic arrangement allows the system to maintain reliable gradation representation by adapting subfield parameters to the light source's luminance state, while preserving relatively simple display panel hardware
Solution Approach 2:
The patent utilizes periodic action by synchronizing subfield arrangements with the AC-driven light source's periodic luminance variations. By strategically positioning subfields at specific points in the luminance cycle and using an adjusting subfield, the system achieves consistent gradation representation that accounts for the periodic nature of the light source operation
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 allows for stable gradation representation across varying luminance levels, improving characteristics on both darker and lighter sides without affecting the light source's AC-driving, thus maintaining consistent image quality.
Implementation Method 1
A light source for emitting light to a display panel is AC-driven to achieve long life. When the light source is AC-driven, because the luminance of light emitted is changed
Implementation Method 2
a display panel has a display element, such as a liquid crystal element, for each pixel and changes a transmittance or reflectance of light for each pixel
Data Source
AI summary
An image display apparatus includes a light-source driving circuit that drives a light source to cyclically change brightness. A control unit controls a pixel to turn on and off over a plurality of subfields in a field so that transmittance or reflectance in the pixel over the plurality of subfields in the field corresponds to a gray level specified for the pixel. The control unit also arranges the plurality of subfields such that two or more gray-level defining subfields maintain a predetermined relationship with respect to the cyclical change in brightness of the light source caused by drive of a light-source driving circuit.