Watch Crown Assembly Optical Encoder and Conductive Path
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Solution Overview
Problem
Existing wearable electronic devices face challenges in forming a conductive path through intricate crown components while maintaining electrical isolation to prevent grounding, which affects the effectiveness of biometric sensing and input functionality.
Innovation Solution
A crown assembly with a conductive path defined by a rotatable component and a friction guard, where the optical encoder component contacts the friction guard instead of the shaft, forming a conductive path that couples the user's input to biometric sensing circuitry while isolating it from the housing, and a polymer-encapsulated conductor ensures electrical insulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the optical encoder component directly contacts the crown shaft to detect rotation, then rotational input detection is achieved, but electrical isolation is compromised and grounding issues occur
Solution Approach 1:
A non-conductive optical encoder component is introduced as an intermediary between the crown shaft and the detection system. This component transmits rotational motion through optical features without direct electrical contact, maintaining isolation while enabling rotation detection. The optical encoder component defines optical features that move with the crown shaft during rotation but remains electrically isolated from it.
2Ease of operation
If the crown assembly rotates directly against internal components, then rotational input is transmitted, but friction damage occurs to internal components
Solution Approach 1:
A friction guard component is introduced as a protective intermediary between the rotating crown assembly and stationary internal components. The friction guard absorbs rotational friction through its shear plate design, preventing direct contact and potential damage to the switch and other internal components while still allowing rotational input transmission.
Solution Approach 2:
The friction guard with its shear plate design provides preemptive protection against friction damage. The shear plate is specifically designed to deflect and absorb friction forces before they can reach and damage more sensitive internal components like the switch, cushioning the harmful effects in advance.
3Adaptability or versatility
If a conductive path is formed through the crown assembly for biometric sensing, then biometric sensing functionality is enabled, but electrical grounding is compromised
Solution Approach 1:
The conductive path is localized to specific regions where needed for biometric sensing (through the crown shaft and friction guard), while other regions maintain electrical isolation. The optical encoder component remains non-conductive in areas where isolation is critical, creating different electrical properties in different locations of the same assembly.
Solution Approach 2:
The optical encoder component serves as an intermediary that transmits mechanical rotation without electrical contact. Its non-conductive nature maintains electrical isolation in critical areas while allowing the conductive path to be established through other designated components for biometric sensing functionality.
4Adaptability or versatility
If multiple components are used to define the conductive path, then biometric sensing is enabled, but device complexity increases
Solution Approach 1:
The crown shaft serves multiple functions: it transmits rotational input to the optical encoder, provides structural support, and acts as part of the conductive path for biometric sensing. This multi-functionality reduces the need for separate dedicated components, simplifying the overall structure despite the multiple roles required.
Solution Approach 2:
The conductive path is formed by merging the functional roles of existing components (crown shaft, friction guard) rather than adding entirely new separate components. This integration approach enables biometric sensing capability while minimizing the increase in device complexity by utilizing and combining the functions of already-present elements.
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 effective rotational and translational inputs, protects internal components from friction damage, and allows biometric sensing without grounding issues, enhancing the durability and functionality of the crown input system.
Implementation Method 1
an optical detector configured to detect rotation of the crown assembly by detecting motion of the group of optical features
Implementation Method 2
the crown assembly may rotate against the friction guard when the crown assembly is rotated, and the friction guard may protect the switch from rotational friction from the crown assembly
Data Source
AI summary
An electronic watch may include a housing defining a side wall having a through-hole and a crown assembly including an actuation member. The actuation member may include a crown shaft extending through the through-hole and having an exterior portion defining an input surface and a crown ring coupled to the exterior portion of the crown shaft and electrically isolated from the crown shaft. The crown assembly may further include an optical encoder component attached to the actuation member and defining a group of optical features. The electronic watch may further include an optical detector configured to detect rotation of the crown assembly by detecting motion of the group of optical features and an electrocardiograph sensor comprising a sensing component. The sensing component may be conductively coupled to the actuation member via a conductive path at least partially defined by the crown shaft.