Electric Shaver Motor Voltage Control via Load Detection
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Solution Overview
Problem
Existing electric shavers consume power unnecessarily when not in contact with skin, and existing solutions require additional sensors to detect skin contact, increasing complexity.
Innovation Solution
An electric shaver that uses a load detector to measure motor power consumption, switching the motor voltage between two levels based on detected thresholds, eliminating the need for a distance sensor by varying the duty cycle of a controllable switch to optimize power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shaver operates continuously at high power to ensure readiness for skin contact, then the shaving performance is maintained, but power consumption increases and battery life decreases
Solution Approach 1:
The shaver dynamically adjusts its operating state between high-power mode (when skin contact is detected) and low-power mode (when no skin is detected), allowing the system to adapt its power consumption to actual operational needs while maintaining readiness when required
Solution Approach 2:
The proximity sensor provides continuous feedback about skin contact status, enabling the control system to automatically switch between power states based on real-time detection, ensuring the shaver is ready to shave when needed while conserving energy during non-use periods
2Use of energy by moving object
If a proximity sensor is added to detect skin contact and switch on the shaver, then power consumption is reduced, but device complexity increases
Solution Approach 1:
The proximity sensor serves multiple functions: detecting skin contact for automatic power switching, providing feedback for adaptive power management, and enabling intelligent operation modes, thereby justifying its addition through multiple benefits rather than a single function
Solution Approach 2:
The shaver system automatically detects skin contact and adjusts its own power state without user intervention, with the proximity sensor and control system working together to self-regulate power consumption based on operational conditions
3Duration of action of stationary object
If the shaver switches on just prior to skin contact using a proximity sensor, then battery life is prolonged, but the device becomes uncomfortable to use due to pulling and tugging when off
Solution Approach 1:
The shaver dynamically transitions between off and on states based on proximity detection, remaining off during non-contact movement to ensure comfort, and switching on only when skin contact is detected or imminent, eliminating pulling and tugging sensations
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 solution effectively reduces power consumption without additional sensors, ensuring efficient operation by detecting skin contact through motor current measurement, thereby prolonging battery life and simplifying the device.
Implementation Method 1
a load detector arranged to measure at least one electric parameter indicative of a power consumption of the motor to obtain a measured value
Implementation Method 2
The controller is arranged to switch the average voltage between a first average voltage level and a second average voltage level... by varying the duty cycle of a controllable switch
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention relates to an electric shaver (1) comprising a cutter unit (3), an electric motor (4), a load detector arranged to detect a load current of the motor (4) and a controller. The controller switches the average voltage from a first level to a second level once the load current exceeds a first threshold value (TH_TH), and switches the average voltage from the second level back to the first level if the load current falls below a second threshold value (TH_TL) and stays below the second threshold value (TH_TL) for a predefined timeperiod. By operating on a lower energy consumption when the cutter unit of the shaver is not in contact with the skin, energy is saved without the need for a proximity sensor.