Imperceptible Flickering Multi-Color Lights for SSVEP
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional steady-state visual evoked potential (SSVEP) techniques using mono-color flickering lights at lower frequencies cause visual fatigue and potential health issues like migraine and seizure attacks, limiting their application in everyday life due to discomfort and safety concerns, and struggle to encode visual stimuli into display images effectively.
Innovation Solution
A stimuli-generating method and device using imperceptible flickering multi-color lights, combining a stimulating light source with specific characteristics and a compensating light source to minimize flickering perception, with frequencies above the critical fusion frequency, reducing discomfort and allowing safe, real-time brain state monitoring and alteration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If lower frequency flickering lights are used to induce SSVEP signals, then signal intensity is stronger and easier to detect, but visual fatigue and discomfort are caused to the viewer
Solution Approach 1:
The patent segments the flickering light into multiple color channels (e.g., red, green, blue) that flicker at different frequencies. Each color component can be independently modulated to contribute to the SSVEP response while the combined multi-color stimulus prevents visual fatigue by distributing the flicker across different spectral regions that the human visual system processes differently.
Solution Approach 2:
The patent changes the parameters of the flickering light by using multiple frequencies simultaneously across different color channels rather than a single frequency. This allows the system to maintain strong SSVEP signal intensity while avoiding the visual discomfort associated with low-frequency monochromatic flicker, as the brain responds to the composite multi-frequency stimulus differently than to single-frequency flicker.
2Measurement precision
If lower frequency flickering lights are used to induce SSVEP signals, then signal intensity is stronger, but diseases such as migraine and seizure attacks may be caused to the viewer
Solution Approach 1:
The patent divides the stimulus into multiple color-frequency segments, where each color channel flickers at a different frequency. This segmentation prevents any single frequency from reaching the threshold that triggers pathological responses in sensitive individuals, while the combined effect across multiple channels maintains sufficient signal intensity for reliable SSVEP detection.
Solution Approach 2:
The patent converts the potential harm of high-intensity flicker into a benefit by using the fact that the human visual system has different temporal resolution for different colors. By assigning different flicker frequencies to different color channels, the system creates a stimulus that is both effective for inducing SSVEP and safe from triggering migraines or seizures, as the multi-color composition masks the individual flicker frequencies.
3Reliability
If mono-color and simple patterns are used as visual stimuli, then SSVEP signals can be induced, but the patterns cannot be combined to display videos and images viewed by ordinary viewers
Solution Approach 1:
The patent merges the SSVEP stimulus function with the image display function by modulating the backlight or display elements with multi-frequency, multi-color patterns that simultaneously encode visual information for normal viewing and SSVEP-inducing frequencies for brain response. This allows the display to show videos and images to ordinary viewers while embedded frequency modulations induce measurable SSVEP responses for brain-computer interfacing applications.
Solution Approach 2:
The patent makes the display system universal by enabling it to perform multiple functions: displaying visual content for normal viewing and inducing SSVEP responses for brain monitoring or control. The multi-color, multi-frequency stimulus pattern serves both purposes simultaneously, allowing the same device to be used for both conventional display applications and advanced brain-computer interfacing without requiring separate systems.
4Measurement precision
If lower flickering frequencies are used for visual stimuli, then SSVEP signals are stronger, but distortion of encoded images occurs and additional digital image processing techniques are required
Solution Approach 1:
The patent changes the temporal parameters of the light modulation by using higher flickering frequencies that are above the critical fusion frequency for human perception. This allows the encoded images to be displayed without visible flicker or distortion, while the multi-color, multi-frequency modulation scheme maintains sufficient SSVEP signal intensity for reliable detection, eliminating the need for additional digital image processing to correct distortions.
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 enables safe and comfortable brain-computer interfacing with reduced risks of discomfort or pathological side effects, while maintaining image quality and allowing for real-time brain state monitoring and alteration, improving physiological and psychological conditions.
Implementation Method 1
the combination of the stimulating light and the compensating light—which is referred collectively as the imperceptible stimuli thereof—flicker near or above the critical fusion frequency (CFF) threshold of the composite color light in human vision
Data Source
AI summary
Visual or photic stimuli generating methods, devices and control systems for inducing steady-state visual evoked potential (SSVEP) from human viewers without causing discomfort to the viewers or distorting the embedding images are disclosed. The control system includes a stimuli-generating device and an electroencephalography (EEG) sensing device. The stimuli-generating device includes a first and a second light source. The first light source generates a flickering light with a first wavelength while a second light source generates another flickering light with one or more wavelength(s) differ from that of the first one. Together, the light sources generate visual/photic stimuli flickering above their critical flicker fusion threshold while maintaining the colorfulness and hue of the embedding images. At least one electrode of the EEG sensing device is connected to each viewer, configured to receive and analyze his/her EEG signals in order to detect and determine his/her responses to the stimuli.