Pulse Width Modulated LED Data Encoding via Cycle-Dependent Dimming
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Solution Overview
Problem
Current methods for data transmission in wireless interfaces, particularly in buildings, face challenges in efficiently utilizing dimmable light sources for optical data transfer without affecting the perceived brightness, which is essential for both data encoding and illumination control.
Innovation Solution
A method and device that use a pulse width modulated light source with a varying cycle-dependent pulse duty factor to encode data, ensuring the average duty cycle remains consistent with the set dimming factor, allowing for imperceptible changes in brightness that enable data transmission without altering the overall brightness perception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If the pulse duty factor is varied to encode data, then data transmission capability is improved, but the brightness stability deteriorates
Solution Approach 1:
The patent applies periodic action by using pulse width modulation with a fixed period and varying only the pulse width (duty factor) within each period. This allows data encoding through duty factor variation while maintaining a regular periodic structure that enables brightness control and stability, resolving the contradiction between data transmission and brightness stability.
Solution Approach 2:
The patent changes the pulse duty factor parameter to encode data while keeping other parameters (period length, average power) constant. This selective parameter change allows information encoding without affecting the overall brightness perception, as the human eye cannot detect rapid periodic variations.
2Loss of information
If the pulse duty factor is changed to transmit data, then information encoding capability is improved, but the perceived brightness control deteriorates
Solution Approach 1:
By using periodic pulse width modulation with a frequency above the human visual detection threshold, the patent enables data encoding through duty factor variation while the periodic nature ensures the average brightness remains controllable and stable from the human perspective.
Solution Approach 2:
The patent introduces dynamics by allowing the pulse duty factor to vary dynamically according to the data being transmitted, while the overall brightness control remains static and predictable. This dynamic variation within a controlled framework resolves the contradiction between information encoding and brightness control.
3Adaptability or versatility
If pulse width modulation is used for brightness control, then brightness adjustment capability is improved, but data transmission capability deteriorates
Solution Approach 1:
The patent applies multi-functionality by enabling the pulse width modulated light source to perform both brightness control and data transmission functions simultaneously. By encoding data within the pulse duty factor variations that are imperceptible to humans, the same system achieves dual functionality, resolving the contradiction between brightness adjustment and data transmission capabilities.
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
Enables reliable and secure optical data transmission using dimmable light-emitting diodes, achieving synchronization and high data rates while maintaining the brightness control and security against electromagnetic interference.
Implementation Method 1
a pulse width modulated light source is used in which a duty cycle adjusted to control the brightness of the pulse width modulated light source
Implementation Method 2
the sluggishness of the human eye is exploited, which cannot perceive a short-term change in the pulse width modulation as perceptible differences in brightness
Implementation Method 3
the light source is designed as a light-emitting diode which, in addition to the advantages mentioned in the introduction, offers the advantage of a short and precise switch-on time
Data Source
Figure 1A~2B
AI summary
The invention relates to a method and an apparatus for the optical transmission of data by means of a pulse-width modulated light source (LED), in which a set dimming factor (N) is replaced with a cycle-dependent dimming factor (NI), wherein the cycle-dependent dimming factor is modulated for encoding the data to be transmitted and corresponds to the set dimming factor over a time interval which is resolvable for the human eye.