PWM Vibration Motor Controller for Mobile Devices
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Solution Overview
Problem
Mobile communication devices experience degraded vibration due to fluctuations in battery voltage, leading to inconsistent vibration alerts as battery life decreases.
Innovation Solution
Implementing pulse width modulation (PWM) to control the vibration motor, using a motor voltage less than the minimum battery voltage, and adjusting the PWM duty cycle based on current battery voltage to maintain consistent power delivery to the motor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct battery voltage is applied to the vibration motor, then the motor receives sufficient power, but the vibration becomes inconsistent as battery voltage fluctuates
Solution Approach 1:
The patent applies pulse width modulation (PWM) to dynamically adjust the duty cycle based on real-time battery voltage measurements. This dynamic control allows the system to maintain consistent vibration output despite battery voltage fluctuations by varying the on-time proportion of the motor drive signal, thereby resolving the contradiction between power delivery and vibration consistency.
Solution Approach 2:
The system implements a feedback mechanism by continuously monitoring battery voltage and using this information to adjust the PWM duty cycle. The controller reads battery voltage, calculates the appropriate duty cycle to compensate for voltage drops, and applies this to the motor drive signal, ensuring consistent vibration performance throughout battery discharge cycles.
2Reliability
If battery voltage is reduced to match motor voltage requirements, then motor operation becomes stable, but power delivery to the motor decreases
Solution Approach 1:
The patent uses periodic pulse width modulation to deliver power to the vibration motor. Instead of applying a continuous reduced voltage, the system applies periodic voltage pulses with variable duty cycles. This periodic action allows the motor to receive sufficient average power while maintaining stable operation, as the PWM technique effectively delivers higher peak currents during the on-periods to compensate for the reduced average voltage.
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
Ensures a substantially consistent vibration sensation to the user despite variations in battery voltage, maintaining vibration quality over time.
Implementation Method 1
driving the vibration motor using pulse width modulation with a motor voltage which is less than the minimum charge voltage of the battery
Implementation Method 2
a magnet and a rotor are disposed between the first and second cases. A shaft passes through the magnet, the rotor, and the second case, and is rotatably disposed on the first case
Data Source
AI summary
An improved vibration motor controller and method maintains a substantially consistent vibration over time, despite decreasing battery voltage over time, with the controller used in a mobile communication device, the mobile communication device powered by a battery having a maximum charge voltage and a minimum charge voltage, the controller being operative for monitoring the available voltage at the battery; driving the vibration motor using pulse width modulation with a motor voltage which is less than the minimum charge voltage of the battery; and controlling the pulse width modulation used to drive the vibration motor in a manner to provide a substantially consistent power level despite fluctuations in voltage of the battery.