JP2020091200A - Resonance frequency identification device, inspection device, resonance frequency identification method and inspection method - Google Patents

Abstract

To achieve reduction in size of a device, and improvement in work efficiency of a work identifying a resonance frequency.SOLUTION: A resonance frequency identification device, which is configured to enable identification of a resonance frequency fm as a frequency of an AC signal S1 when a deflection angle is maximum in a MEMS mirror element 100 revolving a mirror by a supply of the driving AC signal S1 and changing a deflection angle of reflection light, comprises: a signal output unit 11 that can output the AC signal A1 as changing the frequency; a measurement unit 12 that measures a resistance value R on the basis of an output signal S2 to be output from the MEMS mirror element 100 in a state where the AC signal S1 is supplied to the MEMS mirror element 100; and a processing unit 16 that implements identification processing of identifying the resonance frequency fm on the basis of the frequency when the resistance value R varying accompanied by the change in frequency is an extreme value.SELECTED DRAWING: Figure 1

Description

The present invention relates to a resonance frequency identifying device and a resonance frequency identifying method for identifying a resonance frequency as a frequency of an AC signal for driving when a deflection angle of reflected light in a MEMS mirror element is maximum, and a MEMS based on the resonance frequency. The present invention relates to an inspection device and an inspection method for inspecting a mirror element.

A MEMS mirror element is known as an element that rotates a mirror at a frequency of an AC signal to change a deflection angle of reflected light by supplying an AC signal for driving. In this MEMS mirror element, when an external force having a resonance frequency (mechanical resonance frequency) peculiar to the MEMS mirror element, which is determined by the mass, elastic coefficient, viscosity coefficient, etc. of the mirror or a driving system for driving the mirror, is applied, the mirror and the driving system are Resonate. Therefore, in this MEMS mirror element, the rotation amount of the mirror (that is, the deflection angle of the reflected light) becomes maximum when the frequency of the AC signal is the resonance frequency.

On the other hand, the resonance frequency of the MEMS mirror element to be inspected is used when inspecting the quality of the MEMS mirror element depending on whether or not the resonance frequency is within a reference range, or is driven by an AC signal having a frequency other than the resonance frequency. It is also used for controlling the frequency of the AC signal when driving the MEMS mirror element by switching between the linear mode for driving and the non-linear mode for driving with the AC signal having the frequency of the resonance frequency. As a method of measuring the resonance frequency of this MEMS mirror element, the measuring method disclosed in Patent Document 1 below is known. In this measuring method, a plurality of light receiving elements are arranged within the deflection angle range of the reflected light of the laser beam incident on the MEMS mirror element, and the frequency of the AC signal is set to a certain value and supplied to the MEMS mirror element. The MEMS mirror element is driven, and the deflection angle of the reflected light at that frequency is calculated based on the time when each light receiving element detects the reflected light. Next, this processing is repeatedly executed while changing the frequency of the AC signal, and the frequency of the AC signal when the deflection angle of the reflected light becomes maximum is the resonance frequency (mechanical resonance frequency) of the MEMS mirror element. Specify as.

Japanese Patent No. 5027617 (page 5-14, FIG. 1)

However, the above-mentioned conventional measuring methods have the following problems to be improved. Specifically, the conventional measuring method requires an optical system for emitting a laser beam to be incident on the MEMS mirror element and a light receiving element for detecting reflected light of the laser beam. Since it is necessary to dispose the measurement device at a position distant from the device, there is a problem that the measuring device becomes large. Further, in the conventional measuring method, a long waiting time is required to stabilize the output of the laser beam, so that there is a problem that the work efficiency of the work of specifying the resonance frequency is poor.

The present invention has been made in view of the above problems, and a resonance frequency identifying device, an inspection device, a resonance frequency identifying method, and an inspection method capable of realizing miniaturization of the device and improvement of work efficiency of the operation of identifying the resonance frequency. The main purpose is to provide.

In order to achieve the above object, the resonance frequency specifying device according to claim 1 maximizes the deflection angle in the MEMS mirror element that changes the deflection angle of the reflected light by rotating the mirror by supplying a driving AC signal. A resonance frequency identifying device configured to identify a resonance frequency as a frequency of the AC signal at a time, the signal output unit being capable of outputting the AC signal while changing the frequency, and the AC signal being the MEMS. A measurement unit that measures a predetermined physical quantity based on an output signal output from the MEMS mirror element while being supplied to the mirror element, and the physical quantity that changes with the change of the frequency becomes an extreme value. And a processing unit that executes a specifying process for specifying the resonance frequency based on the relevant frequency.

The resonance frequency specifying device according to claim 2 is the resonance frequency specifying device according to claim 1, wherein the frequency and the physical quantity are extreme values when the actual measurement value of the deflection angle in the MEMS mirror element is maximum. And a storage unit that stores a correction value that is defined in advance based on the frequency, and the processing unit corrects the frequency when the physical quantity becomes an extreme value in the specific processing. The value is corrected with a value, and the corrected frequency is specified as the resonance frequency.

The inspection device according to claim 3 is an inspection unit that inspects the resonance frequency identification device according to claim 1 or 2 and the quality of the MEMS mirror element based on the resonance frequency identified by the resonance frequency identification device. It has and.

Further, the resonance frequency specifying method according to claim 4 is the alternating current when the deflection angle becomes maximum in the MEMS mirror element that rotates the mirror by supplying an AC signal for driving to change the deflection angle of the reflected light. A resonance frequency specifying method for specifying a resonance frequency as a frequency of a signal, wherein the output signal is output from the MEMS mirror element in a state where the AC signal is being supplied to the MEMS mirror element while changing the frequency. Based on this, a predetermined physical quantity is measured, and a specifying process of specifying the resonance frequency is executed based on the frequency when the physical quantity that changes with the change of the frequency becomes an extreme value.

The resonance frequency specifying method according to claim 5 is the resonance frequency specifying method according to claim 4, wherein in the specifying process, the frequency when the measured value of the deflection angle in the MEMS mirror element becomes maximum The frequency when the physical quantity becomes the extreme value is corrected with a correction value that is defined in advance based on the frequency when the physical quantity becomes the extreme value, and the corrected frequency is specified as the resonance frequency. To do.

The inspection method according to claim 6 inspects the quality of the MEMS mirror element based on the resonance frequency identified by the resonance frequency identification method according to claim 4 or 5.

In the resonance frequency identification device according to claim 1, the inspection device according to claim 3, the resonance frequency identification method according to claim 4, and the inspection method according to claim 6, the alternating signal is applied to the MEMS mirror element while changing the frequency. The resonance frequency is measured based on the frequency when the physical quantity determined in advance is measured based on the output signal output from the MEMS mirror element in the state of being supplied and the physical quantity that changes with the change of the frequency reaches the extreme value. A specific process for specifying is executed. Therefore, according to the resonance frequency identifying device, the inspection device, the resonance frequency identifying method, and the inspection method, the deflection of the reflected light is increased by using a large device including a light source that outputs the incident light and a detection unit that detects the reflected light. The electrical resonance frequency is specified by a simple configuration in which the resistance value is measured based on the output signal output from the MEMS mirror element in the state where the AC signal is supplied, without performing the complicated work of actually measuring the angle. The mechanical resonance frequency can be easily specified based on the electric resonance frequency. Further, in this resonance frequency identifying device, the inspection device, the resonance frequency identifying method, and the inspection method, since the light source is not used, it is not necessary to wait to stabilize the output of the incident light from the light source, and the resonance frequency is identified. The processing time can be shortened sufficiently. Therefore, according to this resonance frequency specifying device, the inspection device, the resonance frequency specifying method, and the inspection method, it is possible to surely realize the downsizing of the device and the improvement of the work efficiency of the work of specifying the resonance frequency.

Further, according to the resonance frequency specifying device according to claim 2, the inspection device according to claim 3, the resonance frequency specifying method according to claim 5, and the inspection method according to claim 6, in the specifying process, in the MEMS mirror element. With a correction value specified in advance based on the frequency (mechanical resonance frequency) when the actual measured deflection angle is maximum and the frequency (electrical resonance frequency) when the resistance value is extreme. A more accurate resonance frequency can be specified by correcting the frequency when the resistance value becomes the extreme value and specifying the corrected frequency as the resonance frequency.

It is a block diagram which shows the structure of the inspection apparatus 1. FIG. 3 is an explanatory diagram illustrating a configuration and an operation of the MEMS mirror element 100. FIG. 6 is a first relationship diagram showing a relationship between a frequency f of an AC signal S1 and a resistance value R. It is a flowchart of the specific process 50. FIG. 6 is a second relationship diagram showing a relationship between the frequency f of the AC signal S1 and the resistance value R.

Hereinafter, embodiments of the resonance frequency identifying device, the inspection device, the resonance frequency identifying method, and the inspection method will be described with reference to the accompanying drawings.

First, the configuration of the inspection device 1 shown in FIG. 1 as an example of the inspection device will be described. The inspection apparatus 1 is configured to inspect the quality of the MEMS mirror element (for example, the MEMS mirror element 100 shown in FIGS. 1 and 2).

Here, the MEMS mirror element 100 is one form of a MEMS (Micro Electro Mechanical Systems) element, and as shown in FIG. 2, a mirror 101, an actuator 102 for driving the mirror, and a control (not shown) for controlling the actuator. A circuit and the like are formed on the substrate 103 by a fine processing technique. In this case, the MEMS mirror element 100 rotates and enters the mirror 101 by supplying an AC signal for driving (an AC signal S1 output from a signal output unit 11 described later), as conceptually shown in FIG. It has a function of changing the deflection angle θ of the reflected light L2 of the incident light L1 (for example, laser light), and is used, for example, in a display device or the like that irradiates the screen with the reflected light L2 and displays an image on the screen. Be done.

On the other hand, as shown in FIG. 1, the inspection device 1 is configured to include a signal output unit 11, a measurement unit 12, an operation unit 13, a storage unit 14, a display unit 15, and a processing unit 16. In this case, the resonance frequency identifying device is configured by the signal output unit 11, the measuring unit 12, and the portion of the processing unit 16 excluding the function of performing the inspection process described later, and the deflection frequency in the MEMS mirror element 100 is formed by the resonance frequency identifying device. A resonance frequency (mechanical resonance frequency fm described later) as the frequency f of the AC signal S1 when θ becomes maximum is specified.

The signal output unit 11 outputs a driving AC signal S1 (for example, AC constant current) under the control of the processing unit 16. In this case, the signal output unit 11 is configured to be able to output while changing the frequency f (see FIG. 3) of the AC signal S1.

The measuring unit 12 measures the voltage value V (voltage effective) of the output signal S2 (AC voltage) output from the MEMS mirror element 100 while the AC signal S1 output from the signal output unit 11 is being supplied to the MEMS mirror element 100. Value), the impedance is obtained based on the current value I (current effective value) of the AC signal S1, the voltage value V, and the phase difference between the AC signal S1 and the output signal S2, and then the absolute value of the obtained impedance. From this, the resistance value R (an example of a predetermined physical quantity) is obtained (measured). In this case, the measurement unit 12 measures the resistance value R every time the frequency f of the AC signal S1 output from the signal output unit 11 is changed (see FIG. 3 ). In the inspection apparatus 1, as shown in FIG. 1, the probes 21a and 21b connected to the signal output unit 11 and the probes 22a and 22b connected to the measurement unit 12 are connected to two terminals of the MEMS mirror element 100. Contact and measure the resistance value R by the four-terminal method.

The operation unit 13 includes various buttons and keys, and outputs an operation signal when these are operated.

The storage unit 14 stores the correction value fc used in the specific process 50 executed by the processing unit 16. Here, the correction value fc is the frequency f when the measured value of the deflection angle θ of the reflected light L2 measured while changing the frequency f of the AC signal S1 supplied to the non-defective MEMS mirror element 100 is the maximum. (It is a mechanical resonance frequency, and this frequency f is also referred to as "resonance frequency fm" hereinafter) and the frequency f when the resistance value R has an extreme value (minimum value or maximum value) (electrical resonance frequency). It is a frequency, and hereinafter, this frequency f is also defined in advance as "resonance frequency fe". In this case, in this example, the difference value between the resonance frequency fm and the resonance frequency fe is defined as the correction value fc. The storage unit 14 also stores the resonance frequency fm specified in the specifying process 50. The storage unit 14 also stores a reference range fa used in the inspection process executed by the processing unit 16.

Under the control of the processing unit 16, the display unit 15 displays the resonance frequency fm specified in the specifying process 50 executed by the processing unit 16 and the result of the inspection process executed by the processing unit 16.

The processing unit 16 controls the signal output unit 11, the measurement unit 12, the storage unit 14, and the display unit 15 according to the operation signal output from the operation unit 13, and executes various processes. Specifically, the processing unit 16 measures the resonance frequency fm as the frequency f of the AC signal S1 when the deflection angle θ of the reflected light L2 of the incident light L1 incident on the mirror 101 of the MEMS mirror element 100 becomes maximum. The specifying process 50 (see FIG. 4) for specifying based on the resistance value R measured by the unit 12 is executed. In this case, in the specific process 50, the processing unit 16 sets the resistance value R, which changes with the change of the frequency f of the AC signal S1 supplied to the MEMS mirror element 100, to an extreme value (a minimum value or a maximum value). The resonance frequency fm is specified based on the frequency f when The processing unit 16 also functions as an inspection unit, and executes inspection processing for inspecting the quality of the MEMS mirror element 100 based on the resonance frequency fm identified by the identification processing 50.

Next, a resonance frequency specifying method for specifying the resonance frequency fm of the MEMS mirror element 100 using the inspection apparatus 1 and an inspection method for inspecting the quality of the MEMS mirror element 100 based on the specified resonance frequency fm will be described with reference to the drawings. Explain.

First, the resonance frequency fm (mechanical resonance frequency) of the MEMS mirror element 100 to be inspected is specified using the inspection device 1. Specifically, as shown in FIG. 1, the probes 21a and 21b connected to the signal output unit 11 and the probes 22a and 22b connected to the measurement unit 12 are brought into contact with two terminals of the MEMS mirror element 100. Then, the operation unit 13 is operated to instruct execution of the specific process.

Next, the processing unit 16 executes the specific process 50 shown in FIG. 4 according to the operation signal output from the operation unit 13. In the specifying process 50, the processing unit 16 instructs the signal output unit 11 to start output of the AC signal S1 and instructs the measuring unit 12 to start measuring the resistance value R (step 51). In response to this, the signal output unit 11 starts outputting the AC signal S1. In this case, the signal output unit 11 sets the frequency f of the AC signal S1 to a predetermined initial value, starts the output of the AC signal S1, and sets the frequency f at a predetermined time interval. The output of the AC signal S1 is continued while changing (for example, increasing) each value.

Further, in response to an instruction from the processing unit 16, the measuring unit 12 starts measuring the resistance value R. In this case, the measurement unit 12 causes the voltage value V (voltage effective value) of the output signal S2 (AC voltage) output from the MEMS mirror element 100 along with the supply of the AC signal S1 (AC constant current) to the MEMS mirror element 100. Is detected, the impedance is obtained based on the current value I (current effective value) of the AC signal S1, the voltage value V, and the phase difference between the AC signal S1 and the output signal S2, and then the resistance is calculated from the absolute value of the obtained impedance. The process of measuring the value R is repeatedly executed in association with the change of the frequency f of the AC signal S1 by the signal output unit 11 (at the time interval when the signal output unit 11 changes the frequency f).

Subsequently, the processing unit 16 stores the resistance value R measured by the measurement unit 12 in the storage unit 14 in association with the frequency f (step 52). Next, the processing unit 16 instructs the signal output unit 11 to stop the output of the AC signal S1 at the time when the frequency f of the predetermined AC signal S1 reaches the predetermined frequency, and the measuring unit 12 Is instructed to end the measurement of the resistance value R (step 53). In response to this, the signal output unit 11 stops outputting the AC signal S1, and the measurement unit 12 ends the measurement of the resistance value R.

Subsequently, the processing unit 16 reads out the resistance value R for each frequency f measured by the measurement unit 12 from the storage unit 14, and then changes the resistance value R with respect to the change in the frequency f to determine the extreme value of the resistance value R ( The frequency f when it becomes the maximum value or the minimum value is specified (step 54).

In this case, when the RLC series resonance circuit is configured by the actuator 102 and the control circuit that configure the MEMS mirror element 100, as shown in FIG. 3, the frequency f of the AC signal S1 supplied to the MEMS mirror element 100 resonates. The resistance value R has a minimum value at the frequency (electrical resonance frequency fe). Therefore, in this case, the frequency f when the resistance value R becomes the minimum value can be specified as the electrical resonance frequency fe of the MEMS mirror element 100. Further, when the RLC parallel resonance circuit is configured by the actuator 102 and the control circuit that configure the MEMS mirror element 100, as shown in FIG. 5, the frequency f of the AC signal S1 supplied to the MEMS mirror element 100 is the resonance frequency. The resistance value R has a maximum value at (electrical resonance frequency fe). Therefore, in this case, the frequency f when the resistance value R reaches the maximum value can be specified as the electrical resonance frequency fe of the MEMS mirror element 100.

Subsequently, the processing unit 16 reads the correction value fc from the storage unit 14 (step 55). In this example, the correction value fc is the frequency when the actual measurement value of the deflection angle θ of the reflected light L2 measured while changing the frequency f of the AC signal S1 supplied to the non-defective MEMS mirror element 100 is the maximum. A difference value (for example, fe-fm) between the mechanical resonance frequency fm which is f and the electric resonance frequency fe which is the frequency f when the resistance value R becomes the extreme value (minimum value or maximum value). Is defined as the correction value fc.

Next, the processing unit 16 specifies the corrected frequency f(fe-fc) by subtracting the correction value fc from the resonance frequency fe as the resonance frequency fm (step 56). Subsequently, the processing unit 16 stores the identified resonance frequency fm in the storage unit 14 and causes the display unit 15 to display the resonance frequency fm (step 57), and ends the identification process 50. With the above, the identification of the resonance frequency fm is completed.

Here, the inventors actually measure the deflection angle θ of the reflected light L2 while changing the frequency f of the AC signal S1 supplied to the MEMS mirror element 100, and the deflection angle θ of the reflected light L2 becomes maximum. The resonance frequency fm (mechanical resonance frequency), which is the frequency f at that time, is specified, and the resistance value R of the MEMS mirror element 100 is changed while changing the frequency f of the AC signal S1 supplied to the MEMS mirror element 100. Results of a verification test in which the resonance frequency fe (electrical resonance frequency), which is the frequency f when the resistance value R becomes the extreme value, is measured and the resonance frequency fm and the resonance frequency fe are compared. It has been found that the resonance frequency fm and the resonance frequency fe substantially match. For this reason, the inventor takes this fact directly and specifies the resonance frequency fm based on the electric resonance frequency fe (the resonance frequency fe as it is or by correcting the resonance frequency fe). An identification device and resonance frequency identification method have been developed.

In this case, in the resonance frequency identifying device and the resonance frequency identifying method, the deflection angle θ of the reflected light L2 is measured by using a large-sized device including a light source that outputs the incident light L1 and a detection unit that detects the reflected light L2. The electrical resonance frequency fe is specified by a simple configuration in which the resistance value R is measured based on the output signal S2 output from the MEMS mirror element 100 in a state where the AC signal S1 is supplied, without performing complicated work. It is possible to easily specify the mechanical resonance frequency fm based on the resonance frequency fe. Further, in this resonance frequency specifying device and the resonance frequency specifying method, since the light source is not used, it is not necessary to wait for stabilizing the output of the incident light L1 from the light source, and therefore the processing time for specifying the resonance frequency fm is sufficient. It is possible to shorten to.

Further, in the resonance frequency identifying device and the resonance frequency identifying method, the mechanical resonance frequency fm obtained by actually measuring the deflection angle θ and the electrical resonance frequency fe obtained by measuring the resistance value R of the MEMS mirror element 100. By correcting the resonance frequency fe with the correction value fc defined in advance based on the above, it is possible to specify the resonance frequency fm more accurately.

Then, the operation unit 13 is operated to instruct execution of the inspection. In response to this, the processing unit 16 executes the inspection process. In this inspection process, the processing unit 16 reads out the resonance frequency fm of the MEMS mirror element 100 to be inspected identified in the identification process 50 from the storage unit 14, and the reference range fa for determining the quality of the MEMS mirror element 100. Is read from the storage unit 14. Subsequently, the processing unit 16 determines whether the resonance frequency fm is within the reference range fa. In this case, when the resonance frequency fm is within the reference range fa, it is determined that the MEMS mirror element 100 is a good product, and when the resonance frequency fm is outside the reference range fa, it is determined that the MEMS mirror element 100 is a defective product. To do.

The specified resonance frequency fm is also used for purposes other than the inspection of the MEMS mirror element 100 described above. Specifically, the MEMS mirror element 100 is used in the linear mode driven by the AC signal S1 having a frequency f other than the resonance frequency fm and the non-linear mode driven by the resonance frequency fm. Therefore, the specified resonance frequency fm is also used when controlling the frequency f of the AC signal S1 when switching the two modes to drive the MEMS mirror element 100.

As described above, in the resonance frequency identifying device, the inspection device 1, the resonance frequency identifying method, and the inspection method, the output from the MEMS mirror element 100 while the AC signal S1 is being supplied to the MEMS mirror element 100 while changing the frequency f. The resistance value R is measured based on the output signal S2 that is generated, and a specific process that specifies the resonance frequency fm based on the frequency f when the resistance value R that changes with the change of the frequency f becomes the extreme value is executed. To do. Therefore, according to the resonance frequency specifying device, the inspection device 1, the resonance frequency specifying method, and the inspection method, reflection is performed by using a large-sized device including a light source that outputs the incident light L1 and a detection unit that detects the reflected light L2. The resistance value R is measured based on the output signal S2 output from the MEMS mirror element 100 with the AC signal S1 supplied, without performing the complicated work of measuring the deflection angle θ of the light L2. It is possible to easily specify a mechanical resonance frequency fe and to easily specify a mechanical resonance frequency fm based on the resonance frequency fe. In addition, in the resonance frequency identifying device, the inspection device 1, the resonance frequency identifying method, and the inspection method, since the light source is not used, it is not necessary to wait for stabilizing the output of the incident light L1 from the light source, and therefore the resonance frequency fm. It is possible to sufficiently reduce the processing time for specifying Therefore, according to the resonance frequency specifying device, the inspection device 1, the resonance frequency specifying method, and the inspection method, it is possible to surely realize the downsizing of the device and the improvement of the work efficiency of the work of specifying the resonance frequency fm.

Further, according to the resonance frequency identifying device, the inspection device 1, the resonance frequency identifying method, and the inspection method, the frequency f (mechanical) when the actual measurement value of the deflection angle θ in the MEMS mirror element 100 becomes maximum in the identifying process. Of the resonance frequency fm) and the frequency f (electrical resonance frequency fe) when the resistance value R becomes the extreme value, the resistance value R becomes the extreme value with a correction value fc that is defined in advance. A more accurate resonance frequency fm can be specified by correcting the frequency f and specifying the corrected frequency f as the resonance frequency fm.

The resonance frequency identification device, the inspection device, the resonance frequency identification method, and the inspection method are not limited to the above configurations and methods. For example, the example in which the resistance value R is used as the predetermined physical quantity has been described above, but the voltage value V of the output signal S2 detected by the measuring unit 12 is used as the predetermined physical quantity and the frequency f is changed. A configuration and method for identifying the resonance frequency fm based on the frequency f when the changing voltage value V reaches the extreme value can also be adopted.

In addition, the example in which the signal output unit 11 is configured to be capable of outputting the AC constant current as the AC signal S1 has been described above, but a current output that outputs the AC current as the AC signal S1 (normal AC current instead of AC constant current). The signal output unit 11 may be configured to include a unit and a current measuring unit that measures the current value I of the alternating current.

Further, the difference value (fe-fm) between the resonance frequency fm and the resonance frequency fe of the good MEMS mirror element 100 is defined as the correction value fc, and the corrected frequency f(fe is subtracted from the resonance frequency fe to correct the correction value fc. The example in which −fc) is specified as the resonance frequency fm has been described above. However, the ratio (fm/fe) between the resonance frequency fm and the resonance frequency fe is defined as the correction value fc, and the resonance frequency fe is multiplied by the correction value fc. A configuration and method of specifying the corrected frequency f(fe×fc) as the resonance frequency fm can also be adopted.

Further, the configuration and method for correcting the resonance frequency fe with the correction value fc and specifying the corrected frequency f as the resonance frequency fm have been described above, but the difference between the resonance frequency fm and the resonance frequency fe may be small. When the resonance frequency fm of the MEMS mirror element 100 that is known in advance is specified, the correction process may be omitted and the resonance frequency fe may be directly specified as the resonance frequency fm.

1 inspection device 11 signal output unit 12 measurement unit 14 storage unit 16 processing unit 100 MEMS mirror element 101 mirror f frequency fc correction value fe resonant frequency fm resonant frequency L2 reflected light R resistance value S1 AC signal S2 output signal V voltage value θ swing Horn

Claims (6)

The resonance frequency as the frequency of the AC signal when the deflection angle is maximum in the MEMS mirror element that rotates the mirror by changing the deflection angle of the reflected light by supplying the driving AC signal is specified. A resonance frequency identifying device,
A signal output unit capable of outputting the AC signal while changing the frequency,
A measuring unit that measures a predetermined physical quantity based on an output signal output from the MEMS mirror element while the AC signal is being supplied to the MEMS mirror element;
A resonance frequency identification device, comprising: a processing unit that executes a specification process that identifies the resonance frequency based on the frequency when the physical quantity that changes with the change in the frequency reaches an extreme value. A storage unit that stores a correction value defined in advance based on the frequency when the measured value of the deflection angle in the MEMS mirror element becomes maximum and the frequency when the physical quantity reaches an extreme value ,
The resonance frequency identification according to claim 1, wherein in the identification processing, the processing unit corrects the frequency when the physical quantity reaches an extreme value with the correction value and identifies the corrected frequency as the resonance frequency. apparatus. An inspection apparatus comprising: the resonance frequency identification device according to claim 1; and an inspection unit that inspects the quality of the MEMS mirror element based on the resonance frequency identified by the resonance frequency identification device. Resonance frequency identification for identifying the resonance frequency as the frequency of the AC signal when the deflection angle is maximum in the MEMS mirror element that rotates the mirror by changing the deflection angle of the reflected light by supplying the driving AC signal Method,
A physical quantity determined in advance based on an output signal output from the MEMS mirror element while the AC signal is being supplied to the MEMS mirror element while changing the frequency is measured. A resonance frequency specifying method for executing a specifying process for specifying the resonance frequency based on the frequency when the changing physical quantity reaches an extreme value. In the specific processing, the correction value is defined in advance based on the frequency when the actual measurement value of the deflection angle in the MEMS mirror element is maximum and the frequency when the physical quantity is an extreme value. The resonance frequency specifying method according to claim 4, wherein the frequency when the physical quantity reaches an extreme value is corrected, and the corrected frequency is specified as the resonance frequency. An inspection method for inspecting the quality of the MEMS mirror element based on the resonance frequency specified by the resonance frequency specifying method according to claim 4.

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