Oscillatory Wave Drive Voltage Step-Down Circuit

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Solution Overview

Problem

Existing oscillatory wave motor control systems face challenges in performing feedback control from the early stage of rotation due to high minimum input voltage requirements for phase difference detection, which is limited by voltage step-down circuits and variations in resistance values, leading to inaccurate phase difference judgment and turbulence in traveling wave oscillations.

Innovation Solution

An oscillatory wave drive device with a voltage step-down circuit having a resistance voltage dividing ratio between 1/1 and 1/20, and the use of noise cut means like condensers in the circuit to reduce frequency response differences, allowing for correct phase difference judgment at lower input voltages and enabling feedback control from the early stage of rotation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a voltage step-down circuit with conventional resistance dividing ratio is used, then the phase difference detection can be performed, but the minimum input voltage requirement is high which prevents feedback control from early stage of rotation

Engineering Contradiction:
Improvephase difference detection accuracyVSAvoidminimum input voltage requirement
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent changes the voltage dividing ratio parameter of the resistance voltage dividing circuit from conventional values (typically 1/10 or higher) to a specific range of 1/5 to 1/50. This parameter change allows the circuit to operate with lower input voltages while maintaining sufficient signal level for accurate phase difference detection, thereby enabling feedback control from the early stage of motor rotation.

Inventive Principle:
Principle #35Parameter changes

2Ease of manufacture

If resistance values in voltage step-down circuit vary, then manufacturing tolerances are accommodated, but phase difference judgment becomes inaccurate leading to turbulence in traveling wave oscillations

Engineering Contradiction:
Improveresistance value toleranceVSAvoidphase difference judgment accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent specifies a relatively wide voltage dividing ratio range of 1/5 to 1/50, which provides a margin of tolerance for resistance value variations. By designing the circuit to operate correctly across this range, the system accommodates manufacturing tolerances while ensuring that phase difference judgment remains accurate enough to prevent turbulence in traveling wave oscillations.

Inventive Principle:
Principle #16Partial or excessive action

3Use of energy by moving object

If feedback control is delayed until higher rotation speeds, then circuit voltage requirements are met, but rotation control precision and stability are reduced

Engineering Contradiction:
Improvecircuit operating voltageVSAvoidrotation control precision
Core Design Contradiction:
Use of energy by moving objectVSManufacturing precision

Solution Approach 1:

The patent enables feedback control to begin from the early stage of rotation by using the modified voltage step-down circuit that can operate at lower voltages. This preliminary action allows the control system to start regulating rotation precisely from the beginning of motor operation, rather than waiting until higher speeds are achieved, thereby improving overall rotation control precision and stability.

Inventive Principle:
Principle #10Preliminary action

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 enables precise rotation control and feedback control from the early stage of rotation, improving the stability and speed of oscillatory wave motor operations, particularly in optical apparatus applications like autofocus systems.

Implementation Method 1

an oscillatory type (oscillatory wave) actuator has a vibrator in which drive oscillation is excited in an elastic body of an annular shape, a long oval shape, a rod shape, or the like by applying electric signals, such as an alternating voltage, to an electromechanical energy conversion element, such as a piezoelectric element

Methodology Applied
Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

the use of noise cut means like condensers in the circuit to reduce frequency response differences

Methodology Applied
Scientific EffectCapacitance filtering: Capacitance

Data Source

PatentEP2930841B1Oscillatory wave drive device and optical apparatus
Publication Date: 2019.06.12 CANON KK
  • EP2930841B1 patent drawingFigure 1
  • EP2930841B1 patent drawingFigure 2~3
  • EP2930841B1 patent drawingFigure 4

AI summary

An oscillatory wave drive device has an oscillatory wave driving unit having an electromechanical energy conversion element having drive phases and a detection phase, a diaphragm (13), and a rotor (725c), in which a traveling wave is generated on the surface of the diaphragm (13) of the electromechanical energy conversion element to drive the rotor (725c), and the driving speed of the rotor (725c) is controlled based on a signal of the phase difference detecting unit. In the oscillatory wave drive device, a detection phase voltage step-down unit and a drive phase voltage step-down unit each containing a resistance voltage dividing circuit having at least two resistors are provided and the voltage dividing ratio in the resistance voltage dividing circuit of the detection phase voltage step-down unit is lower than 1/1 and higher than 1/20.