Rotatable Crown Wiper Encoder for Precision Angle Detection
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Solution Overview
Problem
Traditional rotary encoders for electronic devices face limitations in precision and direction detection due to optical sensing of indicia, which restricts their ability to accurately determine the angular position, direction, and speed of rotation.
Innovation Solution
A compact rotary encoder design featuring a user-rotatable shaft with wipers that travel along a resistance member, providing multiple contact points and outputs, which are processed by an analog-to-digital converter to determine the angular position, direction, or speed of rotation, allowing precise control of electronic device functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If optical sensing of indicia is used in traditional rotary encoders, then the structure is simple, but the measurement precision is limited by the minimum achievable size and spacing of the indicia
Solution Approach 1:
The patent replaces optical sensing with a resistive contact-based measurement system. Instead of using optical indicia, the invention employs wipers that contact a resistance member to detect angular position through electrical resistance changes, thereby eliminating optical component limitations and achieving higher precision without complex optical structures
Solution Approach 2:
The invention changes the measurement parameter from optical characteristics (light transmission/reflection) to electrical resistance. By measuring resistance changes at multiple contact points along the rotation path, the system achieves high-resolution angular position detection with a relatively simple mechanical structure
2Measurement precision
If optical sensing is used to detect rotation direction, then the implementation is straightforward, but the ability to detect direction of rotation is limited by the minimum indicia spacing
Solution Approach 1:
The patent substitutes optical direction detection with electrical contact-based detection. Multiple wipers contact the resistance member at different angular positions, and the system determines rotation direction by analyzing the sequence and magnitude of resistance changes, eliminating the need for closely spaced optical indicia
Solution Approach 2:
The invention divides the rotation detection into multiple discrete contact points along the resistance member. By segmenting the angular measurement into multiple resistance measurement points, the system can detect rotation direction with higher precision without requiring tightly spaced indicia
3Measurement precision
If multiple wipers are used to provide multiple contact points, then the measurement precision and direction detection improve, but the device complexity increases
Solution Approach 1:
The patent combines multiple wipers and their corresponding resistance contact points into a single integrated resistance member structure. The multiple contact points are formed as part of the same resistive element, allowing simultaneous measurement at different angular positions without requiring separate independent components for each measurement point
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 high-resolution, precise control of electronic device functions such as graphical outputs and audio volumes by accurately determining the rotation angle, direction, and speed, overcoming the limitations of traditional rotary encoders.
Implementation Method 1
a resistance member on a contact surface; a user-rotatable shaft; an array of ground taps separating the resistance member into segments of uniform resistivity; a first wiper and a second wiper affixed to the user-rotatable shaft, the first wiper configured to generate a first output and the second wiper configured to generate a second output based on a relative position of the first wiper or the second wiper with respect to the resistance member
Data Source
AI summary
A compact crown for an electronic device such as an electronic watch, including a set of wipers capable of determining a rotation angle, rotation direction, or rotation speed, is disclosed. The set of wipers is in contact with at least one resistance member at different angular positions around a rotation axis. The crown may have a group of ground taps disposed along the resistance member and a measured signal may vary based on the position of each wiper as it contacts the at least one resistance member. A compact crown may also include capacitive members and capacitive sensors in order to similarly determine rotation angle, rotation direction, or rotation speed.