Optical Encoder Axial Movement Detection for Smartwatches

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Solution Overview

Problem

Conventional rotary encoders in smartwatches face challenges in accurately detecting movement along the axis while maintaining miniaturization and cost-effectiveness, particularly in determining the axial position and extent of button presses regardless of rotational orientation.

Innovation Solution

The proposed solution involves using optical encoders with visible markings or diameter variations on the rotary shaft, combined with light source and detector arrangements that measure distance changes to detect axial movement, allowing for reliable detection of button presses and extended states through step changes or notches, and employing self-mixing interference techniques with VCSELs for compact and cost-efficient distance and velocity measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional rotary encoders are used to detect axial movement, then detection capability is provided, but device size and cost increase

Engineering Contradiction:

Improveaxial movement detectionVSAvoidencoder component count

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent combines axial position detection and rotational position detection into a single optical encoder system. The same light source, optical axis, and detector are used for both functions, eliminating the need for separate detection mechanisms and reducing overall device complexity while maintaining detection precision for both axial and rotational movements.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The optical encoder is designed to perform multiple functions: detecting axial movement of the rotary shaft, detecting rotational position, and determining button press states. This multi-functional approach replaces what would traditionally require multiple separate sensors and components, thereby reducing device size and cost while maintaining comprehensive detection capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Volume of moving object

If miniaturization is pursued for smartwatch encoders, then device size is reduced, but detection reliability deteriorates

Engineering Contradiction:

Improveencoder sizeVSAvoidmovement detection accuracy

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent uses the angular dimension around the rotary shaft to enable axial position detection. By detecting changes in reflected light intensity as the shaft rotates, the system can determine axial position without requiring additional axial space for separate sensors. This dimensional approach allows miniaturization while maintaining detection reliability through clever use of the existing rotational degree of freedom.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Reliability

If traditional button press detection mechanisms are used, then press detection is reliable, but device complexity and cost increase

Engineering Contradiction:

Improvebutton press detectionVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces traditional mechanical button press detection mechanisms (such as separate push buttons or mechanical switches) with an optical detection system. The same optical encoder that detects axial and rotational position also detects button press states by monitoring axial position changes, eliminating the need for additional mechanical components and reducing manufacturing complexity and cost.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 enables precise detection of axial movement and button press states, offering improved reliability and miniaturization, while reducing component count and cost, and allowing for quantitative axial position determination, enhancing control capabilities in smartwatches and other devices.

Implementation Method 1

The light source is arranged to emit light towards a surface of the rotary shaft and the detector is arranged to detect intensity variations in reflected light from the surface of the rotary shaft

Methodology Applied

Scientific EffectLight reflection: Reflection

Implementation Method 2

employing self-mixing interference techniques with VCSELs for compact and cost-efficient distance and velocity measurements

Methodology Applied

Scientific EffectSelf-mixing interference: Interference

Data Source

PatentUS20240159573A1Apparatus and method for detecting movement along an axis

Publication Date: 2024.05.16 AMS OSRAM ASIA PACIFIC PTE LTD

AI summary

An apparatus may provide a control signal based on an axial position of a controller displaceable along an axis. The apparatus may include a component for displacement with said controller along said axis, a radiation source and detector arrangement configured to direct radiation towards a target region and generate a detector signal dependent upon radiation reflected from within that target region, and a computer processor configured to process said detector signal to determine a measure of distance or change of distance to a reflecting surface region within said target region, and to use said measure to provide said control signal. The component may define a reflecting surface that passes through said target region such that a reflecting surface region is present within said target region with a distance that varies with the axial position of the component along said axis.