Driving Chip Digital Control for Micro LED Color Shift
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Solution Overview
Problem
Micro LED displays face the challenge of color shift due to varying driving currents, which complicates the pixel circuits and makes them unsuitable for high pixel density displays, as the brightness and wavelength of micro LEDs are correlated with the driving current.
Innovation Solution
A driving chip with digital-to-analog converters (DACs) and control circuits that provide input voltages and emission control signals to manage light emission periods, allowing pixel circuits to emit light for specific time lengths based on voltage levels, thereby controlling the light emission duration and reducing color shift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pixel circuits provide driving currents with fixed magnitude and variable pulse width to micro LED, then color shift phenomenon is overcome, but pixel circuit structures become complicated
Solution Approach 1:
The patent extracts the pulse width modulation function from the pixel circuit and relocates it to a dedicated control circuit. The pixel circuit is simplified to only provide fixed magnitude driving current, while the control circuit independently manages the emission timing and duration, thereby separating the complexity from the pixel circuit while maintaining color consistency.
Solution Approach 2:
The patent introduces a control circuit as an intermediary between the pixel circuit and the micro LED. This control circuit receives emission control signals, determines the light emission time length based on the first voltage level duration, and controls the pixel circuit accordingly, thus simplifying the pixel circuit structure while achieving precise brightness control without color shift.
2Ease of manufacture
If pixel circuits are simplified for high pixel density displays, then manufacturing feasibility improves, but control precision over light emission duration may be reduced
Solution Approach 1:
The patent controls the light emission duration not by adjusting the driving current magnitude within the pixel circuit, but by controlling the time dimension - specifically, the duration for which the emission control signal maintains the first voltage level. This temporal control approach allows simplified pixel circuits to achieve precise emission time control, enabling high pixel density displays with accurate brightness management.
Data Source
AI summary
A display device including a driving chip and a pixel array is provided. The driving chip is configured to provide multiple emission control signals according to a data input. A pixel array is coupled with the driving chip. M pixel circuits of the pixel array are configured to emit light respectively in M periods, and M is a positive integer. In a corresponding period of the M periods, the driving chip determines a first time length which one of the multiple emission control signals has a first voltage level, and one of the M pixel circuits emits light, in the corresponding period, for a light emission time length corresponding to the first time length.