Piezo Lens Drive Circuit Duty Ratio Modulation
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Solution Overview
Problem
Existing lens cleaning systems for imaging units on vehicles require complex drive circuits with booster circuits to adjust voltage for different vibration modes, increasing manufacturing costs and complexity.
Innovation Solution
An optical device with a piezoelectric element and drive circuit that adjusts the effective voltage by changing the duty ratio of the driving signal without altering the peak-to-peak voltage, allowing for efficient switching between atomization and heating modes to remove foreign matter from the lens surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a booster circuit is added to adjust voltage for different vibration modes, then the cleaning effectiveness is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent applies parameter changes by modifying the duty ratio of the AC signal to vary the effective voltage applied to the piezoelectric element. Instead of using a booster circuit to change voltage amplitude, the system changes the temporal distribution of voltage (duty ratio) to achieve different effective heating and atomization modes, thereby simplifying the drive circuit while maintaining cleaning effectiveness
Solution Approach 2:
The patent replaces the electrical voltage adjustment mechanism (booster circuit) with a temporal signal control mechanism (duty ratio modulation). By substituting the need for voltage transformation hardware with a software-controlled signal timing approach, the system eliminates complex electrical components while achieving the same functional outcome
2Productivity
If maximum power is used during vibration of the light transmitting body, then the foreign matter removal efficiency is improved, but the system complexity increases due to requiring circuits and wiring that withstand maximum power
Solution Approach 1:
The patent applies periodic action by using pulsed AC signals with varying duty ratios to drive the piezoelectric element. Instead of continuous maximum power application, the system uses periodic on-off cycling where the duty ratio controls the average power delivery. This achieves effective foreign matter removal through repeated vibration cycles while reducing peak power requirements and simplifying system components
Solution Approach 2:
The patent maintains continuous useful action by ensuring the piezoelectric element receives periodic driving signals that keep the light transmitting body in constant vibration. The duty ratio modulation ensures that within each cycle, the element receives sufficient energy input to maintain effective cleaning action, while the overall periodic nature allows for reduced peak power requirements
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 removes foreign matter without the need for booster circuits, reducing manufacturing costs and complexity while ensuring efficient operation in both atomization and heating modes.
Implementation Method 1
a piezoelectric element configured to vibrate the vibration body
Data Source
AI summary
An optical device is provided for removing foreign matter adhering to a surface of a light transmitting body. The optical device includes an outermost layer lens, a housing, a vibration body, a piezoelectric element, and a drive circuit. The drive circuit causes a voltage of a driving signal that drives the piezoelectric element in an atomization mode to vibrate the outermost layer lens to be the same as a voltage of a driving signal that drives the piezoelectric element in a heating mode. The drive circuit drives the piezoelectric element such that an effective voltage applied to the piezoelectric element within a predetermined time period in the atomization mode is different from an effective voltage applied to the piezoelectric element within the predetermined time period in the heating mode.