Capacitive Grip Detection for Accidental Switch Prevention
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Solution Overview
Problem
Handheld personal care devices, such as electric razors, often experience unintended operation when carried in a bag due to accidental activation of the operation switch, and existing solutions like lock mechanisms complicate user operations or fail to reliably prevent erroneous activations.
Innovation Solution
A handheld personal care device equipped with a sensor electrode that detects capacitance changes when grasped, allowing a control device to lock or unlock the operation switch based on user interaction, eliminating the need for manual locking and preventing unintended starts without adding operational complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lock mechanism is equipped on the operation switch to prevent unintended operation, then reliability is improved, but device complexity increases and ease of operation deteriorates
Solution Approach 1:
The patent replaces the mechanical lock mechanism with a sensor-based detection system. A sensor electrode detects capacitance changes when the device is grasped, and a control unit automatically controls the operation switch based on this detection, eliminating the need for mechanical lock components and reducing device complexity while maintaining reliability
Solution Approach 2:
The device performs automatic lock and unlock operations through sensor detection without requiring user intervention. The control unit automatically determines whether to enable or disable the operation switch based on grasp detection, making the system self-regulating and eliminating complex manual locking procedures
2Reliability
If a lock mechanism is equipped on the operation switch, then reliability is improved, but ease of operation worsens due to required lock operations
Solution Approach 1:
The control unit automatically performs lock and unlock operations based on sensor detection results, eliminating the need for users to manually execute lock operations. The system serves itself by automatically enabling the operation switch when grasped and disabling it when not grasped, simplifying user interaction while ensuring reliability
3Reliability
If the operation switch is locked automatically, then reliability is improved, but ease of operation worsens as users may forget to unlock
Solution Approach 1:
The sensor electrode continuously monitors grasp status and provides feedback to the control unit. When the device is grasped, the control unit detects this through capacitance change and automatically unlocks the operation switch. This continuous feedback loop ensures the switch is always in the appropriate state, eliminating user memory dependencies while maintaining reliability
Solution Approach 2:
The control unit automatically manages the lock state based on real-time sensor input, eliminating the need for users to remember to lock or unlock the switch. The system autonomously adjusts its operational state according to whether it is being held, ensuring both reliability and user convenience
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
The solution effectively prevents unintended operation of the device when carried in a bag and automatically locks the switch after use, ensuring reliable operation without requiring user intervention, thus enhancing user convenience and safety.
Implementation Method 1
a sensor electrode that is embedded in the grip unit, and causes a change in capacitance depending on whether or not the grip unit is grasped
Data Source
AI summary
A handheld personal care device according to the present disclosure includes: an operation switch configured to change a treatment operation of an operation unit; a sensor electrode configured to cause a change in capacitance depending on whether or not the grip unit is grasped; and a control device electrically connected to the operation switch and the sensor electrode and configured to control the treatment operation of the operation unit. The control device includes: a grasp detector configured to detect that the grip unit is grasped based on a change in capacitance of the sensor electrode; and a change permission part configured to permit the operation switch to change the treatment operation of the operation unit when the change permission part receives, from the grasp detector, grasp information indicating that the grip unit is grasped.