Head-Mounted Eye-Tracking Optics for Stable Image Resolution
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Solution Overview
Problem
The structural limitations in head-mounted electronic devices make it difficult to secure a stable light path between the eye tracking camera and the user's pupil, leading to reduced resolution of image data.
Innovation Solution
The device incorporates a first lens unit, a second lens unit, and a third lens unit with specific optical axes and configurations to correct the angle of light incidence, including a third lens unit with asymmetric and aspheric shapes to enhance image data resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the eye tracking camera is disposed at a position to receive reflected light from the user's pupil without interfering with the display light path, then the device structure is simplified, but the resolution of image data obtained through the camera is reduced due to unstable light path
Solution Approach 1:
The patent introduces a beam splitter as an intermediary optical element positioned between the display and the eye tracking camera. The beam splitter divides the light path, allowing display light to pass through to the user's pupil while simultaneously directing reflected light from the pupil toward the camera. This mediator enables both functions to coexist without direct interference, resolving the contradiction between simplified structure and image resolution.
Solution Approach 2:
The optical system is segmented into distinct functional zones: a display light path for visual output and a camera light path for eye tracking. The beam splitter creates separate optical channels that operate simultaneously but independently, allowing the camera to capture reflected light without blocking the display light path, thus maintaining both structural simplicity and imaging quality.
2Adaptability or versatility
If the camera is positioned to capture reflected light from the user's pupil, then eye tracking function is enabled, but the light path stability is compromised leading to reduced image quality
Solution Approach 1:
The beam splitter serves as a stable intermediary that creates reliable optical pathways. By positioning the beam splitter at a fixed angle (typically 45 degrees) in the optical path, the system ensures consistent light direction and stable image capture, enabling reliable eye tracking functionality without compromising light path stability.
Solution Approach 2:
The patent utilizes spatial dimensionality by introducing the beam splitter at an angular offset from the main optical axis. This dimensional separation allows the camera to capture light from a different angular perspective while maintaining a stable and defined light path, thereby enabling eye tracking without sacrificing reliability.
3Measurement precision
If multiple lens units with different optical axes are used to correct light incidence angles, then image data resolution is improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple lens units (first lens unit, second lens unit, and third lens unit) into a single integrated optical assembly. These lens units with different optical axes are merged to work together in correcting light incidence angles, achieving improved image resolution while consolidating the optical structure rather than using separate independent components.
Solution Approach 2:
The multi-lens unit assembly serves multiple functions simultaneously: the first lens unit focuses display light, the second lens unit captures reflected light, and the third lens unit corrects incidence angles. This universal optical assembly handles both display and eye tracking functions with enhanced resolution, reducing the need for separate specialized components.
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
This configuration reduces degradation in image data resolution by stabilizing the light path and improving the performance of eye tracking and facial feature detection in head-mounted electronic devices.
Implementation Method 1
the third lens unit is configured to correct an angle at which at least a portion of the second light passed through the first lens unit is incident on the second lens unit
Implementation Method 2
the first lens unit may be configured to focus the first light output from the display onto a pupil of the user's eye
Implementation Method 3
the second light, in which the light emitted from the at least one light emitting unit is reflected from the user's face, may be incident on the first lens unit
Data Source
AI summary
A head-mounted electronic device includes a display, a first lens unit having a first optical axis through which first light output from the display passes, a second lens unit having a second optical axis that is different from the first optical axis, a third lens unit having a third optical axis that is different from the first optical axis and the second optical axis, wherein the third lens unit is between the first lens unit and the second lens unit; and an image sensor configured to receive second light through the first lens unit, the second lens unit, and the third lens unit, wherein the third lens unit is configured to correct an angle at which at least a portion of the second light passed through the first lens unit is incident on the second lens unit.