Display Device Pseudo Lighting Reduction via Inverted Weighting
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Solution Overview
Problem
Conventional display devices using light emitting diodes (LEDs) experience significant pseudo lighting due to accumulated electric charges in parasitic capacitance, leading to reduced display quality and erroneous lighting.
Innovation Solution
A display apparatus is designed with a voltage scanner, current driver, and lighting controller that time-divisionally applies voltage and controls lighting periods to reduce pseudo lighting by aligning weighted elements in a different order within sub-frames, ensuring the weighted element at the end of the timeline turns OFF, thereby reducing parasitic capacitance charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional weighting control is used to determine positions to be lit, then gradation control is achieved, but significant pseudo lighting is caused due to accumulated electric charges in parasitic capacitance
Solution Approach 1:
The patent inverts the conventional weighting control approach by reversing the order of weighted elements in the timeline. Instead of using ascending or descending order, the weighted elements are arranged in reverse order where the element with the largest weight is positioned earlier in the timeline. This inversion allows the light emitting element to be turned off before the parasitic capacitance charging cycle completes, thereby eliminating pseudo lighting while maintaining gradation control precision.
Solution Approach 2:
The patent introduces dynamic adjustment of the weighting element order based on the timing requirements of the light emitting element's OFF period. The control system dynamically determines the optimal arrangement of weighted elements to ensure sufficient OFF time for discharge of parasitic capacitance, adapting the weighting sequence to the specific timing constraints of the display refresh cycle and parasitic capacitance characteristics.
2Ease of operation
If weighted elements are arranged in regular order (ascending or descending), then control simplicity is maintained, but pseudo lighting occurs due to insufficient OFF period for parasitic capacitance discharge
Solution Approach 1:
The patent applies inversion by reversing the conventional weighting element order. Instead of simple ascending or descending sequences, the weighted elements are arranged in reverse order with the largest weight positioned first. This inverted arrangement naturally creates sufficient OFF period between the last weighted element activation and the next frame's first element, allowing parasitic capacitance to discharge completely and eliminating pseudo lighting while maintaining control feasibility.
3Duration of action of stationary object
If the light emitting element is kept ON for the entire frame period, then continuous lighting is achieved, but parasitic capacitance accumulates electric charge causing erroneous lighting
Solution Approach 1:
The patent implements periodic action by introducing regular ON and OFF cycles for the light emitting element within each frame period. Instead of continuous ON state, the element is activated during specific weighted element periods and turned off during others, creating periodic lighting patterns that correspond to the gradation requirements. This periodic operation ensures sufficient OFF periods for parasitic capacitance discharge, preventing charge accumulation and erroneous lighting while maintaining necessary lighting duration for display visibility.
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 pseudo lighting and improves display quality by extending the OFF period of light emitting elements, minimizing charging of parasitic capacitance and enhancing the overall display performance.
Implementation Method 1
accumulated electric charges in a parasitic capacitance of a wiring
Data Source
AI summary
A display apparatus time-divisionally expresses gradation values allocated to the sub-frames so that the gradation value of the single frame is expressed by a total of the gradation values of the sub-frames. Each of the plurality of sub-frames includes a plurality of weighted elements with different gradation values to express the gradation values by powers of two. A lighting controller performs control such that the weighted elements in at least one of the plurality of sub-frames in one frame are aligned in an order different from an order of the weighted elements in at least one of the plurality of sub-frames in another frame and, of the plurality of weighted elements in at least one of the plurality of sub-frames in the single frame, the weighted element at the end of the timeline turns OFF a corresponding one of the light emitting elements.