Optical Sensor Assembly Segmentation for Ultra-Low Profile Navigation
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Solution Overview
Problem
Existing optical finger navigation systems in electronic devices require significant vertical space due to the use of light pipes or packaged LEDs with integrated optics, which is not suitable for the miniaturization of smaller devices.
Innovation Solution
The use of a bare LED light source combined with strategically positioned optical elements in the optical sensor assembly, such as reflective surfaces, prisms, and lenses, to direct light to the user interaction area without the need for light pipes, allowing for a thinner profile while maintaining high-quality beam spot size and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If light pipes or packaged LEDs with integrated optics are used to achieve quality tracking performance, then illumination parameters (beam spot area, angular spread, irradiance) are optimized, but vertical space requirement increases to 2-4 mm
Solution Approach 1:
The illumination system is divided into separate functional components: a bare LED die for light generation, individual optical elements (reflectors, lenses) for light manipulation, and a light redirecting element for final direction control. This segmentation eliminates the need for bulky integrated packages and light pipes, reducing vertical space to approximately 1 mm while maintaining the ability to optimize each component independently for tracking performance
Solution Approach 2:
The patent transitions from a vertical stacking architecture (requiring 2-4 mm thickness) to a planar distributed architecture where optical elements are positioned at specific locations around the LED. The light redirecting element uses reflective surfaces positioned at angles to redirect light horizontally across the target area, converting a vertical space problem into a horizontal layout solution that achieves quality illumination within 1 mm vertical clearance
2Volume of moving object
If the vertical space is reduced to enable smaller electronic devices, then device size decreases, but the ability to achieve quality tracking performance is compromised
Solution Approach 1:
Instead of requiring uniform vertical space throughout the device, the patent concentrates optical manipulation at specific local positions around the LED. Reflective surfaces and optical elements are strategically placed at critical locations to achieve proper beam shaping and direction, allowing the rest of the device to be compact. This localized optical control maintains tracking performance while enabling overall device miniaturization
Solution Approach 2:
The patent changes the fundamental parameters of the illumination system by using a bare LED die instead of packaged LEDs, and by employing reflective surfaces with specific angular orientations. These parameter changes enable the system to achieve the required beam spot area, angular spread, and irradiance distribution within a reduced 1 mm vertical space, thereby maintaining tracking performance in smaller devices
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 approach reduces the overall thickness of the optical sensor assembly to about 1 mm, achieving high-quality finger tracking performance within the constrained vertical space, enabling efficient and accurate optical navigation in smaller electronic devices.
Implementation Method 1
The light segmenting optics may include reflective surfaces, prisms, and/or lenses
Implementation Method 2
The light segmenting optics may include reflective surfaces, prisms, and/or lenses
Data Source
AI summary
An optical sensor assembly is disclosed. The optical sensor assembly includes an illumination system that segments light emitted by a light source into multiple segments. The multiple segments are allowed to travel different optical paths on their way to a common target area and are further allowed to irradiate different portions of the common target area. This enables a low-profile optical sensor assembly to be achieved.