Light Sensing Device Lens Positioning for Gesture Detection
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Solution Overview
Problem
Existing light sensing devices in electronic devices face challenges due to cost and manufacturability limitations, requiring high-power illumination sources to compensate for reduced signal amplitude caused by small lens dimensions, leading to increased battery drain.
Innovation Solution
Positioning a lens proximate to the display screen allows for the use of longer focal length lenses, reducing battery power requirements and preventing optical crosstalk through an optical baffle, while maintaining effective light detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a small lens is used in the light sensing device, then the device size is reduced, but the signal amplitude is reduced requiring high-power illumination sources which increase battery drain
Solution Approach 1:
The patent positions the lens proximate to the display screen rather than directly on the photodetector, utilizing the third dimension (depth) to accommodate a larger focal length lens without increasing the planar footprint. This dimensional repositioning allows the lens to have sufficient size for effective light focusing while maintaining a compact overall device form factor.
Solution Approach 2:
The display screen serves as an intermediary element between the external environment and the photodetector. By positioning the lens proximate to the display screen and utilizing light that passes through the display, the system can use lower power illumination sources since the display itself contributes to the light path, reducing the energy burden on the illumination source.
2Ease of manufacture
If the lens is positioned closer to the photodetector, then manufacturing is simplified, but optical crosstalk from the illumination source interferes with detection
Solution Approach 1:
The patent extracts the lens from its traditional position directly on the photodetector and relocates it proximate to the display screen. This separation removes the lens from the immediate vicinity of both the illumination source and photodetector, eliminating the optical crosstalk pathway while maintaining the lens's light-focusing function through the display medium.
Solution Approach 2:
The display screen acts as an optical intermediary that separates the illumination source from the photodetector while still allowing the focused light to reach the detector. This intermediary structure blocks direct optical paths that would cause crosstalk while transmitting the useful focused light signal.
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 battery power consumption and enhances signal amplitude by using lower power illumination sources, while preventing optical interference and allowing for efficient gesture and proximity sensing.
Implementation Method 1
The lens is configured to focus light incident upon the lens and to pass the focused light to the photodetector
Implementation Method 2
light sensors employ photodetectors such as photodiodes, phototransistors, or the like, which convert received light into an electrical signal
Data Source
AI summary
Light sensing devices are described that have a lens to focus light. In one or more implementations, the light sensing devices include a substrate having a photodetector formed thereon. The photodetector is capable of detecting light and providing a signal in response thereto. The devices also include a display screen that allows light to at least substantially pass through the display screen. An optical baffle extends above a surface of the substrate to display screen and is configured to at least substantially prevent transmission of optical crosstalk to the photodetector. The devices also include a lens disposed proximate to the display screen. The lens is configured to focus light incident upon the lens and to pass the focused light to the photodetector.