Optical Position Sensor for Watch Crown Using Reflective Light Detection
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Solution Overview
Problem
Existing input devices, such as watch crowns and joysticks, rely on mechanical mechanisms for motion detection, which can lead to wear and require additional components like dome switches, limiting efficiency and space utilization.
Innovation Solution
An optical sensor assembly that transmits light to a reflector and receives the reflected light, allowing the electronic device to determine the motion of the input mechanism, including rotation, translation, and tilt, without physical contact, using concentric rings of optical energy receivers to detect changes in the reflected light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical mechanisms are used for motion detection, then motion detection capability is achieved, but wear occurs and additional components like dome switches are required
Solution Approach 1:
The patent replaces mechanical motion detection mechanisms with an optical detection system. An optical transmitter emits light that reflects off a reflector attached to the moving shaft, and optical receivers detect the reflected light. This substitution eliminates mechanical contact and wear while maintaining motion detection capability, directly resolving the contradiction between reliability and device complexity.
Solution Approach 2:
The patent introduces an optical intermediary system consisting of a transmitter, reflector, and receiver. The reflector acts as an intermediary that carries motion information from the shaft to the optical receivers without mechanical contact. This intermediary optical path enables wear-free motion detection while simplifying the overall mechanical structure.
2Measurement precision
If mechanical contact mechanisms are used, then motion detection is achieved, but space is consumed by additional components
Solution Approach 1:
The optical detection system replaces bulky mechanical contact mechanisms with a compact light-based detection arrangement. The optical transmitter and receivers can be positioned in close proximity to the reflector, significantly reducing the space required for motion detection components while maintaining measurement precision through optical lever amplification of the shaft's motion.
Solution Approach 2:
The patent transitions from mechanical contact in one dimension to optical detection that can be arranged in multiple dimensions. The concentric rings of optical receivers encircling the transmitter allow for compact three-dimensional arrangement, improving space utilization while maintaining accurate motion detection through the optical path.
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
Enables precise and wear-free motion detection of input devices, conserving space by eliminating the need for mechanical contact and dome switches, while allowing for efficient determination of motion parameters like rotation speed and direction.
Implementation Method 1
An optical energy transmitter transmits optical energy toward the sloped surface, and concentric rings of optical energy receivers that encircle the optical energy transmitter are operable to receive reflected optical energy from the sloped surface
Data Source
AI summary
An electronic device includes an input device having a moveable shaft, a reflective surface, an optical energy transmitter, and optical energy receivers that receive optical energy transmitted by the optical energy transmitter and reflected by the reflective surface. Movement of the moveable shaft changes the optical energy received by the optical energy receivers. The movement or position of the shaft may be determined by analyzing the optical energy received. Detectable movement may include rotation, rotation speed, rotation direction, translation, tilt, displacement, and so on. The optical energy receivers may be configured in concentric rings.