Eyeglass Eye Tracking Layout Using Reflective Lens Illumination
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Solution Overview
Problem
Existing eye tracking devices are bulky and difficult to integrate into glasses frames, especially those with prescription lenses, limiting design flexibility and obstructing the imaging of the eye.
Innovation Solution
An eye tracking device is integrated into the arm portion of a frameset, using a laser flood illuminator positioned within the arm to emit a beam reflected off a lens with a reflective coating, filtered by a camera to capture eye movements, allowing for a compact design that can be incorporated into various framesets, including eyeglass temple arms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing eye tracking devices are used, then eye tracking function is achieved, but the device becomes bulky and difficult to integrate into glasses frames
Solution Approach 1:
The eye tracking device is divided into separate functional modules: a laser flood illuminator positioned in the temple arm, a lens with reflective coating for beam direction, and a camera with filter for eye image capture. This segmentation allows each component to be optimized and positioned independently, enabling compact integration into glasses frames while maintaining full eye tracking functionality.
2Volume of moving object
If a compact design is used, then device size is reduced, but signal-to-noise ratio may deteriorate
Solution Approach 1:
The system uses a laser flood illuminator that emits light at specific wavelengths (e.g., 780nm or 850nm) to illuminate the eye. A bandpass filter with a narrow passband centered at the same wavelength is positioned in the camera optical path. This local optimization of spectral properties ensures that only the laser-reflected light from the eye passes through the filter, dramatically improving the signal-to-noise ratio by rejecting ambient light while maintaining compact device dimensions.
Solution Approach 2:
A lens with a reflective coating is introduced as an intermediary element between the laser flood illuminator and the eye. The reflective coating reflects the laser beam toward the user's eye while allowing the camera to capture the reflected light from the eye. This intermediary enables efficient light direction and collection in a compact configuration, maintaining measurement precision without increasing device size.
3Measurement precision
If laser bandwidth is narrowed to improve filtering, then background light rejection is improved, but device complexity increases
Solution Approach 1:
The system changes the spectral parameter by using a laser flood illuminator with a narrow linewidth (laser bandwidth) operating at a specific wavelength (e.g., 780nm or 850nm). A corresponding bandpass filter with a narrow passband is used to match this wavelength. This parameter optimization allows effective background light rejection while keeping the filtering system simple, as the narrow laser bandwidth naturally defines the spectral window that needs to be passed.
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 compact design enables increased flexibility in frameset design while maintaining an adequate signal-to-noise ratio for eye tracking, reducing power consumption and allowing for a smaller battery, thus integrating seamlessly into glasses without obstructing the user's view.
Implementation Method 1
The beam is reflected off a surface, which in examples may comprise a lens with a near infrared reflective coating, to illuminate an eye of a user.
Implementation Method 2
The returned light from the scattered beam may be reflected off a surface, which in examples may be the same or a different lens of the example pair of glasses. The returned light may then be filtered to remove background light.
Data Source
AI summary
A device may include a frameset having a front frame portion and two arm portions. A device may include a lens coupled to the front frame portion, the lens comprising a reflective coating that is reflective over a laser bandwidth. A device may include a laser flood illuminator positioned within a first arm portion of the two arm portions, the laser flood illuminator transmitting a beam having the laser bandwidth and configured to transmit the beam towards an eye via reflection at the lens. A device may include a camera comprising: a filter configured to receive a returned light from the eye and generate a returned filtered light, the filter having a passband that includes the laser bandwidth, and a sensor operable to receive the returned filtered light and generate a signal. A device may include a processor operable to measure the signal.