Lighting Device Modulation Periods for Camera Blind Spot Avoidance
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Solution Overview
Problem
Portable electronic devices, such as mobile phones and cameras, often have unreliable and reproducible detection of coded light due to their camera limitations, leading to issues with detecting coded light signals.
Innovation Solution
A lighting device with a light emitter that modulates light with periodic changes in modulation periods, avoiding frequency blind spots produced by image capturing units, ensuring detectability by cameras even with fixed exposure times, and using multiple modulation frequencies spaced to avoid inter-modulation effects and human perceptible ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single modulation frequency is used for coded light emission, then the lighting device can maintain stable operation, but cameras with fixed exposure times may produce frequency blind spots causing undetectable signals
Solution Approach 1:
The lighting device dynamically changes its modulation frequency over time, transitioning between multiple frequency states. This dynamic behavior ensures that the modulation frequency does not remain fixed at any single value that could coincide with camera blind spots, thereby improving detection reliability across different camera exposure times.
Solution Approach 2:
The invention changes the modulation frequency parameter of the coded light signal. By varying the frequency within a defined range and avoiding specific blind spot frequencies, the system adapts to different camera characteristics and exposure times, preventing signal loss due to frequency matching issues.
2Reliability
If multiple modulation frequencies are used to avoid blind spots, then detection reliability improves, but the complexity of the lighting control increases
Solution Approach 1:
The lighting device employs periodic switching between different modulation frequency states. This periodic action allows the system to cycle through multiple frequencies in a structured manner, ensuring coverage of detectable ranges while maintaining manageable control complexity through repetitive patterns.
Solution Approach 2:
The system uses feedback mechanisms to monitor detection success and adjust modulation frequencies accordingly. When a frequency is detected as being in a blind spot (through failed detection attempts), the system receives feedback and switches to alternative frequencies, thereby adapting to camera characteristics without requiring complex pre-programming.
3Adaptability or versatility
If modulation frequency is varied to avoid blind spots, then camera detection compatibility improves, but the risk of creating visible flicker increases
Solution Approach 1:
The invention applies different modulation frequencies to different temporal segments of the light output, with each frequency state having specific characteristics optimized for its purpose. The system carefully selects which frequencies to use and for how long, ensuring that variations remain imperceptible to humans while being detectable by cameras.
Solution Approach 2:
The system pre-defines a set of acceptable modulation frequencies and switching patterns that are known to avoid both camera blind spots and human perceptible flicker. By establishing these parameters in advance through careful selection and testing, the system avoids the need for real-time adjustments that could create visible effects.
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
The solution enhances the reliability and reproducibility of coded light detection by cameras, preventing rolling shutter cameras from missing embedded information and ensuring consistent detection across various exposure times and frequencies.
Implementation Method 1
a light emitter arranged to emit light with a periodic modulation which embeds information into the light
Data Source
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AI summary
The possibility to emit and detect coded light, whereby data is modulated into the light, is known. According to one aspect of the present disclosure, to reduce the risk of the modulation going undetected due to possible frequency blind spots in the detection spectrum, the lighting device (2a, 2b, 2c) is arranged such that the frequency of its emitted modulated light (3a, 3b, 3c) shivers around a base, or center, frequency. For example the modulated light (3a, 3b, 3c) may be transmitted using pulse-width-modulation, and the resulting pulse-width-modulation light signal (3a, 3b, 3c) may thus have a period that fluctuates around the base period (T). The parameters determining the shivering of the modulated light (3a, 3b, 3c) may be chosen such that visible flicker in the emitted modulated light (3a, 3b, 3c) is avoided. According to another aspect, the lighting device (2a, 2b, 2c) emits with a plurality of different modulation frequencies simultaneously.