JP5396582B2 - Electromagnetically driven MEMS micro structure drive control method and control apparatus - Google Patents

Description

  The present invention relates to a control method and a control device for removing a response due to mechanical resonance from a motion during driving of a structure having inherent mechanical resonance characteristics in a MEMS microstructure driven by electromagnetic force.

  In the MEMS electromagnetic driving type structure driving, the response characteristic in the mechanical resonance frequency region of the structure is attenuated from the driving signal by a filtering technique to suppress the resonance of the structure.

  The Bessel filter is designed so that the phase rotation is proportional to the frequency, and waveform deformation such as overshoot and ringing can be suppressed as much as possible.

  However, when the drive signal passes through an electronic circuit such as an amplifier or a filter, a time delay or phase rotation always occurs, so that the drive signal waveform becomes dull and noise components increase.

MEMS (Micro Electro Mechanical System) or MOEMS (Micro Opto-Electro Mechanical)
The system application device is configured based on the electromechanical optical effect of the MEMS or MOEMS element.

  The size of the functional unit of the MEMS or MOEMS element ranges from several microns to several millimeters. A minute structure driven by electromagnetic force has inherent mechanical resonance characteristics due to its mass, shape, and structure.

  By utilizing the mechanical resonance characteristics of a minute structure, a large mechanical vibration motion is possible with a small amount of energy, which is advantageous for applications that actively utilize the mechanical resonance phenomenon.

  However, in applications where the mechanical resonance phenomenon must be avoided, the mechanical resonance phenomenon is induced with a small amount of energy, resulting in an application failure.

  When mechanical resonance is induced in the microstructure, the motion of the structure deviates from the motion to be controlled by the drive signal, and the position cannot be determined accurately.

  The frequency spectrum constituting the drive wave of the microstructure having the inherent mechanical resonance characteristic is weighted with the inverse characteristic of the mechanical resonance spectrum of the microstructure, and the microstructure is driven with the drive wave.

  In addition, an actual operation signal is detected from the actual operation of the microstructure, and a mechanical resonance signal component is identified and extracted from the actual operation signal, and is fed back to the drive wave signal to drive the microstructure as a new drive wave. As a result, the remaining mechanical resonance is braked in real time to control the drive characteristics of the microstructure.

  The amplitude of each frequency spectrum component constituting the driving wave of the structure in the process of weighting the frequency spectrum constituting the driving wave of the microstructure having the inherent mechanical resonance characteristic by the inverse characteristic of the mechanical resonance spectrum of the microstructure.・ Set each phase independently.

  It is possible to avoid problems such as time delay occurring when the drive signal passes through an electronic circuit such as an amplifier or a filter, or dullness of the drive signal waveform resulting from phase rotation, and an increase in noise components.

When resonance motion that cannot be ignored when the microstructure is driven by the drive signal remains in the actual operation of the microstructure, the component due to the residual resonance response is identified and extracted from the actual operation signal of the microstructure that changes from moment to moment The microstructure can be driven by a new drive signal that can be negatively fed back to the drive signal, and the residual resonance response can be braked in real time to always minimize the response.

FIG. 1 shows an embodiment of a MEMS electromagnetically driven microstructure. A coil 2 for passing an electric current is formed around a plate-like microstructure 1, the structure 1 is suspended between support pillars 3 a and 3 b by thin and soft hinges 4 a and 4 b, and a direction perpendicular to the support axis of the coil A parallel magnetic field 5 is applied.

Force 7a in a direction perpendicular to the current and the magnetic field both from the Fleming's left hand rule and the coil 2 flow a current 6 of the microstructure 1, 7b acts, the structure 1 and the rotational force by the force The restoring forces 8a and 8b due to the twisting of the hinge are inclined at an angle 9 where the restoring forces 8a and 8b are balanced.

2, current flows 6 to the coil 2 of the microstructure 1, sawtooth wave 10a and the sawtooth wave 10a of the fine small repeating structures 1 as an example of the waveform of the driving frequency f (1-second period f min) Is a frequency characteristic spectrum 10b obtained by Fourier series expansion.

A frequency characteristic spectrum 10b obtained by expanding the sawtooth wave 10a by Fourier series has an amplitude A1, a sine wave of frequency f, an amplitude A2, a sine wave of frequency 2f, ... an amplitude An, a sine wave of frequency nf, ... Starting from a sine wave having a fundamental frequency f, discrete sine wave components are distributed and configured on the high frequency side at a frequency interval f.

In FIG. 3, the microstructure 1 having a mechanical resonance frequency characteristic 11a sampled and displayed with the same discrete sine wave spectrum as the frequency characteristic spectrum 10b obtained by Fourier series expansion of the sawtooth wave 10a is driven by the sawtooth wave 10a. The resulting frequency characteristic spectrum 12a and an example in which excessive vibration due to mechanical resonance appears in the response characteristic 12b on the time axis are shown.

  A driving method for canceling such excessive vibration due to mechanical resonance will be described below.

In FIG. 4, the driving operation of the microstructure 1 is repeated with the sawtooth wave 10a having the frequency f as an example, and the sawtooth wave 10a sampled with the same discrete sine wave spectrum as the frequency characteristic spectrum 10b obtained by Fourier series expansion. By driving the structure 1 with the waveform 14a on the time axis of the frequency characteristic 14b obtained by weighting the frequency characteristic spectrum 10b of the sawtooth wave with the inverse characteristic 13 of the mechanical resonance frequency characteristic 11a of the structure 1 cancel the mechanical resonance characteristics, showing a first aspect of the present invention the content of obtaining the driving operation characteristics 10f on the driving operation characteristics 10e and its frequency axis on the free time axis undue vibration response due to resonance with respect to the structure 1 .

  The repetitive drive to the microstructure 1 has been described by taking a sawtooth wave composed of linear components as an example, but the present invention is applicable to any repetitive drive waveform including a curved component.

Although an example in which the primary mechanical resonance frequency spectrum 11b and the secondary mechanical resonance frequency spectrum 11c exist in the mechanical resonance frequency characteristic 11a of the microstructure 1 has been shown, the resonance frequency spectrum bandwidth is usually narrow and included in this band. There are several discrete sine wave components.

  Sampling errors are introduced when sampling the resonance frequency characteristics unique to the microstructure with several sine waves that are scattered at the frequency interval of the driving wave.

  On the other hand, the resonance characteristics of the microstructure vary due to non-uniformity during the manufacture of the microstructure. The resonance characteristics are affected by operating environment conditions such as temperature and humidity, and the material characteristics of the structure change over time. However, the fluctuation of the resonance characteristic causes a deviation from the typical resonance characteristic.

Therefore, the frequency spectrum composing the driving wave of the microstructure with the inherent mechanical resonance characteristic was driven to cancel the excessive resonance with the driving wave that was uniquely weighted with the inverse characteristic of the mechanical resonance spectrum of the microstructure. Later, a residual resonance component exists in the actual operation of the microstructure.

In order to attenuate this residual resonance component, it is effective to identify and extract the residual resonance component from the signal obtained from the actual operation of the microstructure, negatively feed back the residual resonance component to the drive signal, and brake this residual resonance in real time. a, the describing method are shown below.

  In the embodiment of the microstructure shown in FIG. 1, when a rectangular coil carrying a driving current 6 is placed in an equal magnetic field, the rectangular coil rotates by a force acting between the coil and the magnetic field according to Fleming's left-hand rule. When the magnetic flux to be changed changes, counter electromotive force 10c, 10d is generated in the coil conductor to prevent the magnetic flux change according to the Fleming right-hand rule.

  The counter electromotive forces 10c and 10d can be detected from the actual operation of the microstructure and used as an actual operation signal. There are other means for detecting an actual operation signal from stress change, capacitance change, light deflection angle change, etc., but it is not within the scope of the present invention to describe the details.

5, the minute structure by the real operation signal and identification of components due to the residual resonant response from the source driving wave signal and extracting with new drive signal obtained by the negative feedback the components to a driving signal for a microstructure changes every moment The contents of the second aspect of the present invention for driving the residual resonance response in real time are shown.

The timing of the system is based on the synchronization signal 15, and the source drive wave or its information 17 is supplied from the source drive wave or its information generator 16 to the inverse weighted drive wave generator 18 of the mechanical resonance frequency characteristic . 18 generates an inverse characteristic weighting drive wave 19 of the mechanical resonance frequency characteristic .

The inverse weighted drive wave 19 of the mechanical resonance frequency characteristic is combined with a negative feedback of a residual resonance component 27 (to be described later) by a subtractor 20 to generate a microstructure drive signal 28, and the drive signal is converted into a current by a power amplifier constant current driver 21. The power is amplified to drive the microstructure 22.

  The actual operation of the microstructure 22 is detected by the probe 23, and the actual operation signal is detected by the actual operation signal detector 24. The detector 24 generates an actual operation signal 25, and the signal 25 is extracted from the residual resonance component extractor 26. Send to.

The residual resonance component extractor 25 identifies and extracts a residual resonance component from the source drive wave or its information 17 and the actual operation signal 25, generates a residual resonance signal 27, sends the signal 27 to the subtractor 20, and transmits the machine resonance frequency characteristic. The microstructure driving signal 28 is generated by performing negative feedback synthesis with the inverse characteristic weighting driving wave 19.

FIG. 6 shows a method for identifying and extracting the residual resonance component from the actual operation signal.

  The actual operation signal 25 including the residual resonance signal is sent to the residual resonance component extractor 26, subjected to time differentiation processing by the first time differentiator 29, and a signal 30 is output. A second time differentiation process is performed and a signal 32 is output.

  If the sine wave is time-differentiated twice, the result is that the original sine wave is given a negative sign to the square of its angular frequency. Therefore, the residual resonance component is identified by differentiating the actual operation signal 25 including the residual resonance signal twice. can do.

  Non-linearity exists when the source drive wave of frequency f is configured with a gentle curve component, between the drive wave and the actual operation of the microstructure, or between the actual operation of the microstructure and the actual operation signal 25. In this case, the second time differential result of the actual operation signal 25 does not become zero, and contributions other than these residual resonance components are included in the second time differential result.

  However, the component frequency other than these residual resonance components is generally less than a fraction of the residual resonance frequency, and after the second time differentiation, the component contribution from the components other than the residual resonance component is the contribution of the residual resonance component. Decrease to a few tenths of a level.

  Unnecessary high-frequency noise amplified by the differential processing lowers the high-frequency gain and reduces its influence by circuit technology such as phase compensation.

  Therefore, the residual resonance component can be effectively identified and extracted by the process of differentiating the actual operation signal 25 twice in time.

  The signal 32 after the time differentiation is sent to the output controller 34, the amplitude and phase thereof are adjusted, high frequency noise is removed, the output gate timing is controlled, and the residual resonance signal 27 is output.

  In a series of processing, the system is constructed so that the time progress timing (phase) on the driving waves 17, 19, 25, 27, 28, 30, and 32 of each processing block does not occur with reference to the synchronization signal 15.

7 shows a specific example 1 of the means for driving and controlling the resonance of the microstructure.

A discrete sine wave component included in the mechanical resonance frequency spectrum band of the microstructure is weighted with the inverse characteristic of the mechanical resonance frequency characteristic with respect to the source drive wave having the repetition frequency f , and a new drive signal is generated.

  The synchronization signal generator 35 refers to the synchronization signal 15 and the drive wave generator 36 outputs a drive wave 10a having a repetition frequency f, an amplitude A, and a phase P that drives the microstructure.

Repetition frequency f, amplitude A for driving the microstructure, the frequency spectrum of the drive wave 10a of the phase P is uniquely determined, and because the mechanical resonance frequency spectrum of the microstructure is unique microstructure, mechanical resonance The frequency, amplitude, and phase data of the discrete sine wave for canceling the mechanical resonance for realizing the frequency characteristic 14b weighted by the inverse characteristic of the frequency characteristic are calculated in advance and written in the memory 37.

For example , when the machine resonance canceling discrete sine wave is three waves, the frequency, amplitude, and phase data thereof are read from the memory 37 to the sine wave generator controller 38, and the controller 38 cancels the mechanical resonance canceling sine wave generator 39, 41 and 43 are set to frequency (N−1) f · amplitude AN−1 · phase P, frequency Nf · amplitude AN · phase P, frequency (N + 1) f · amplitude AN + 1 · phase P (N: integer), The generators 39, 41, 43 output sine waves 40, 42, 44 with controlled frequency, amplitude, and phase.

  The sine waves 40, 42, and 44 are added by an adder 47 to generate a mechanical resonance cancellation correction signal 48. The correction signal 48 is input to a subtractor 49 and subtracted from the drive wave signal 10a to generate a new drive signal 14a. .

To flow the drive signal 14a to the coil 2 formed around the fine structure 1 placed in a magnetic field 5 is amplified by the power amplifier constant-current driver 21, perpendicular to both the current and the magnetic field from the Fleming's left The micro structure 1 is driven by applying a force in the direction of.

Figure 8 shows a specific example 2 of the means for driving and controlling the resonance of the microstructure.

A new driving signal is generated by synthesizing the driving wave having the frequency f of the frequency characteristic obtained by weighting the source driving wave having the repetition frequency f with the inverse characteristic of the mechanical resonance frequency characteristic of the microstructure from the m sine waves.

The frequency, amplitude, and phase data of m discrete sine waves that realize the drive wave 14a of the microstructure are calculated in advance and written in the memory 37. The sine wave generator controller 38 uses the sine wave generators 50, 52, and 54. , ... 60, the frequency of the ... 70, to set the amplitude, phase.

Synchronizing signal generator 35 a synchronization signal 15 of m sine wave generator 50, 52, 54 ... 60, sent to ... 70, each sine wave generator frequency constituting a driving wave frequency spectrum 14b , the amplitude, controlled discrete sine wave component of the phase 51, 53, 55, ... 61, to generate a ... 71, the discrete sine wave component 51, 53 and 55, ... 61, - .. 71 is sent to the addition calculator 72 and all are added to generate the drive wave 14a of frequency f.

  The driving wave 14a having the frequency f is amplified by the power amplifier constant current driver 21 and is passed through the coil 2 formed around the microstructure 1 placed in the magnetic field 5. From the left hand rule of Fleming, the direction perpendicular to the current and the magnetic field is obtained. A force is applied to drive the microstructure 1.

Figure 9 illustrates a specific example 3 of the means for driving and controlling the resonance of the microstructure.

The frequency characteristics of the source drive wave with the repetition frequency f are weighted with the inverse characteristics of the mechanical resonance frequency characteristics of the microstructure , and the amplitudes of all the sine wave spectra constituting the frequency characteristics are added on the phase or time axis. The synthesized result is stored in a memory as digital data arranged in time series, and the digital data is sequentially read from the memory and converted from digital to analog to directly generate a microstructure driving wave.

A sequential change on the time axis of the driving wave 14a of the frequency f of the frequency characteristic 14b weighted by the inverse characteristic 13 of the mechanical resonance frequency characteristic of the microstructure in advance is AD-converted from an analog amount to a digital amount and written to the memory 37. .

  The synchronization signal 15 is sent from the synchronization signal generator 35 to the controller 73. The controller 73 controls the memory 37 and the DA converter 74, and the data read from the memory 37 is sent to the DA converter 74 for DA conversion to drive the wave f of frequency f. 14a is output.

  The drive wave 14a having the frequency f is amplified by the power amplifier constant current driver 21 and is passed through the coil 2 formed around the microstructure 1 placed in the magnetic field 5, and is perpendicular to the current and the magnetic field from Fleming's left-hand rule. A force is applied in the direction to drive the microstructure 1.

10 shows a specific example 4 of means for driving the brake the controlling and changes every moment remaining resonating the resonance of a micro structure in real time microstructure.

A discrete sine wave component included in the mechanical resonance frequency spectrum band of the microstructure is weighted with respect to the source drive wave of the repetition frequency f by the inverse characteristic of the mechanical resonance frequency characteristic, and the weighted drive signal is subtracted by the subtractor 20. The residual resonance signal extracted from the actual operation signal of the structure is negatively fed back to drive the microstructure.

11 shows a specific example 5 means for driving the brake the controlling and resonate in real time resonance of microstructure microstructure.

The driving wave of frequency f obtained by weighting the source driving wave of repetition frequency f with the inverse characteristic of the mechanical resonance frequency characteristic of the microstructure is synthesized from m sine waves, and the actual operation of the structure is performed on the weighted driving signal. The subtractor 20 negatively feeds back the residual resonance signal extracted from the signal to drive the microstructure.

Figure 12 shows a specific example 6 of means for driving the microstructure to brake the controlling resonance of the microstructure and resonance in real time.

The frequency characteristics of the source drive wave with the repetition frequency f are weighted with the inverse characteristics of the mechanical resonance frequency characteristics of the microstructure , and the amplitudes of all the sine wave spectra constituting the frequency characteristics are added and synthesized on the phase or time axis. The result is stored in the memory as digital data arranged in time series, the digital data is sequentially read from the memory, converted from digital to analog, and the residual resonance signal extracted from the actual operation signal of the structure is used as the drive signal. Negative feedback to drive the microstructure.

  An apparatus that applies a drive control method of the present invention, which is configured by giving a mirror characteristic to reflect light to an electromagnetically driven MEMS microstructure and removes resonance vibration from the microstructure, includes a projection display device, an image sensor device, and a communication device. It is used for optical application industrial equipment such as

Example of MEMS electromagnetically driven microstructure Example of driving wave and its frequency characteristic spectrum of a microstructure driven by electromagnetic force Effect of resonance characteristics of microstructure driven by electromagnetic force on driving characteristics Invention 1 for controlling resonance characteristics of a microstructure driven by electromagnetic force and driving the structure Invention 2 for extracting the residual resonance component of the microstructure driven by electromagnetic force and braking the resonance in real time A method for identifying and extracting residual resonance components from actual operation signals of microstructures driven by electromagnetic force Specific Example 1 of Means for Controlling and Driving Mechanical Resonance of Microstructure Driven by Electromagnetic Force 1 Specific Example 2 of Means for Controlling and Driving Mechanical Resonance of Microstructure Driven by Electromagnetic Force 2 Specific Example 3 of Means for Controlling and Driving Mechanical Resonance of Microstructure Driven by Electromagnetic Force 3 Specific Example 4 of Means for Controlling Mechanical Resonance of Microstructure Driven by Electromagnetic Force and Braking and Driving Resonance in Real Time Specific Example 5 of Means for Controlling Mechanical Resonance of Microstructure Driven by Electromagnetic Force and Braking and Driving Resonance in Real Time Specific Example 6 of Means for Controlling Mechanical Resonance of Microstructure Driven by Electromagnetic Force and Braking and Driving Resonance in Real Time 6

DESCRIPTION OF SYMBOLS 1 Plate-like microstructure 2 Coil 3a formed around the plate-like microstructure 3a support column 3b for hanging the microstructure A support column 4a for hanging the microstructure 4b hinge 4b for hanging the microstructure Hinge 5 Parallel magnetic field 6 applied to the microstructure 6 Driving current 7a flowing in the coil Force 7b acting in the direction perpendicular to the current and the magnetic field Force 8b acting in the direction perpendicular to the current and the magnetic field 8a Restoring force 8b due to the twist of the hinge the back EMF 10d coil conductors generated to prevent the magnetic flux change in the frequency characteristic spectrum 10c coil conductor sawtooth saw tooth 10b repetition frequency f of the angle 10a repetition frequency f parallel to the restoring force 9 microstructure magnetic field due to the torsion driving operation characteristics 11a fine structure of the driving operation characteristics 10f frequency axis in the counter-electromotive force 10e on the time axis generated to prevent the magnetic flux change Mechanical resonance frequency characteristic of body 11b Primary mechanical resonance frequency spectrum of microstructure 11c Secondary mechanical resonance frequency spectrum of microstructure 12a Frequency characteristic spectrum when a microstructure having mechanical resonance characteristics is driven by a sawtooth wave 12b Mechanical resonance Response characteristics on the time axis in which excessive vibration appears due to the time 13 Inverse characteristics 14a of the mechanical resonance frequency characteristics of the microstructure The characteristics 14b of the time axis of the sawtooth weighted by the inverse characteristics of the mechanical resonance frequency characteristics of the microstructure Frequency characteristic 15 of sawtooth wave weighted by inverse characteristic of machine resonance frequency characteristic of source 15 synchronization signal 16 source drive wave or information generator 17 source drive wave or information thereof 18 machine resonance frequency characteristic inverse characteristic weighted drive wave generator 19 machine Resonance frequency characteristics inverse characteristic weighting drive wave 20 subtractor 21 power amplifier constant current driver 2 2 Microstructure 23 Probe 24 Actual operation signal detector 25 Actual operation signal 26 Residual resonance component extractor 27 Residual resonance component 28 Microstructure drive signal 29 First time differentiator 30 Signal 31 subjected to one time differentiation process Two-time differentiator 32 Two-time differential processing signal 33 Sine wave second-time differential result 34 Output controller 35 Synchronization signal generator 36 Drive wave generator 37 Memory 38 Sine wave generator controller 39 Sine wave generator 40 Sine wave with controlled frequency, amplitude and phase 41 Sine wave generator 42 Sine wave with controlled frequency, amplitude and phase 43 Sine wave generator 44 Sine wave with controlled frequency, amplitude and phase 47 Adder 48 Mechanical resonance canceling correction signal 49 Subtractor 50 Sine wave generator 51 Discrete sine wave component 52 with controlled frequency, amplitude and phase 52 Sine wave Generator 53 Discrete sine wave component 54 with controlled frequency, amplitude, and phase 54 Sine wave generator 55 Discrete sine wave component with controlled frequency, amplitude, and phase 60 Sine wave generator 61 Control of frequency, amplitude, and phase Discrete sine wave component 70 Sine wave generator 71 Discrete sine wave component 72 with controlled frequency, amplitude, and phase 72 Addition calculator 73 Controller 74 DA converter

JP-A-8-249678

Claims (2)

That negatively it fed back to the real time component obtained the actual operation signal detected from the actual operation of the MEMS microstructure by differentiating twice the time to drive wave was weighted inverse characteristic of the mechanical resonance frequency characteristics of the MEMS microstructure A drive control method for a MEMS microstructure, which is characterized . Negative feedback that in real time negatively feeds back to the driving wave weighted by the inverse characteristic of the mechanical resonance frequency characteristic of the MEMS microstructure, the component obtained by differentiating the actual operation signal detected from the actual operation of the MEMS microstructure twice in time. A drive control apparatus for a MEMS microstructure, comprising a circuit .

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