JP2018097143A - Optical module and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical module and an electronic apparatus that can be driven with high accuracy.SOLUTION: The optical module includes: a wavelength variable interference filter having two reflection films opposing to each other via an inter-reflection film gap and a gap varying part varying the inter-reflection film gap to a gap amount depending on an applied voltage; a booster circuit driven by a predetermined drive pulse to increase a reference voltage; a gap detector detecting the gap amount; and a voltage output part driven by an output voltage of the booster circuit and outputting an application voltage responding to the detection value of the gap detector. The gap detector detects the gap amount in a non-varying period where the voltage of the drive pulse does not vary.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an optical module and an electronic apparatus.

  Conventionally, a tunable interference filter having an electrostatic actuator that changes a dimension (gap amount) of a pair of opposing reflection films and a gap between the reflection films, and voltage control that controls a driving voltage (applied voltage) of the electrostatic actuator. An optical module including a unit is known (see, for example, Patent Document 1).

  In Patent Document 1, the voltage control unit includes a gap detector that detects the gap amount, and controls the voltage applied to the electrostatic actuator based on the detection result of the gap detector. Thereby, the applied voltage of the electrostatic actuator can be controlled so that the gap amount becomes a target value, and the adjustment accuracy of the gap amount can be improved.

Japanese Patent Laying-Open No. 2015-66611

By the way, in Patent Document 1, the wavelength variable interference filter can be appropriately driven by applying a drive voltage having an amplitude range of 20 V to 40 V, for example, to the electrostatic actuator. The driving voltage of the electrostatic actuator is higher than the driving voltage of various circuits such as a microcomputer constituting the voltage control unit. For this reason, it is necessary to provide a voltage control unit or a peripheral device that supplies power to the voltage control unit with a booster circuit (for example, a boost chopper circuit or a charge pump circuit) for outputting a drive voltage in the amplitude range. .
However, when a booster circuit is provided, the gap amount detection accuracy in the gap detector may decrease due to the influence of switching noise generated by the switching operation of the booster circuit, and the gap amount adjustment accuracy may decrease accordingly. is there. In this case, it is difficult to drive the variable wavelength interference filter with high accuracy.

  An object of the present invention is to provide an optical module and an electronic apparatus that can be driven with high accuracy.

  An optical module according to an application example of the invention includes two reflection films facing each other via a gap between the reflection films, and a wavelength provided with a gap changing unit that changes the gap between the reflection films according to an applied voltage. A variable interference filter, a booster circuit that is driven by a predetermined drive pulse and boosts a reference voltage, a gap detector that detects the gap amount, and a detection value of the gap detector that is driven by the output voltage of the booster circuit And a voltage output unit that outputs the applied voltage in accordance with the gap detector, wherein the gap detector detects the gap amount during a non-fluctuation period in which the voltage of the drive pulse does not fluctuate.

  In this application example, the voltage output unit is driven by the output voltage from the booster circuit that is driven by a predetermined drive pulse, and outputs the applied voltage to the gap changing unit based on the detected value of the gap amount of the gap detector. . The gap detector detects the gap amount in a non-fluctuating period in which the voltage of the driving pulse does not fluctuate. In such a configuration, even if noise corresponding to a change in the drive pulse occurs in the booster circuit driven by a predetermined drive pulse, the influence of the noise can be suppressed, and the detection accuracy of the gap amount can be improved. It is possible to improve the accuracy of adjusting the gap amount. Therefore, the optical module can be driven with high accuracy.

In the optical module of this application example, the gap detector includes a capacitor that holds a charge corresponding to the gap amount, a sample-and-hold circuit that detects a voltage of the capacitor that holds the charge, and an input of the capacitor A first switch that switches connection and disconnection between the end and the output end, a second switch that switches connection and disconnection between the capacitor and the wavelength variable interference filter, and a connection and disconnection between the capacitor and the sample and hold circuit. It is preferable that the third switch is switched during the non-variation period of the drive pulse.
In this application example, when the first switch is on, the input end and the output end of the capacitor are connected, that is, short-circuited. In addition, when the first switch is off and the second switch is on, the capacitor and the wavelength variable interference filter are connected, and charges corresponding to the gap amount of the wavelength variable interference filter are accumulated in the capacitor. Further, when the third switch is on, the capacitor and the sample and hold circuit are connected, and the voltage corresponding to the electric charge accumulated in the capacitor is detected by the sample and hold circuit. In this application example, the gap detector switches the third switch during the non-fluctuation period of the drive pulse. Thereby, in the period (detection period) in which the sample and hold circuit detects the voltage, the voltage of the drive pulse does not fluctuate, so that the influence of the noise in the detection period can be suppressed.

In the optical module of this application example, it is preferable that the gap detector connects the capacitor and the wavelength tunable interference filter by switching the second switch in the non-variation period of the drive pulse.
In this application example, since the gap detector switches the second switch during the non-fluctuating period, it is possible to suppress the influence of the noise when the electric charge corresponding to the gap amount is accumulated in the capacitor. Therefore, the amount of charge accumulated in the capacitor, that is, the voltage of the capacitor can be set to an appropriate value corresponding to the gap amount, and the accuracy of detecting the gap amount can be improved.

In the optical module of this application example, the gap detector may be configured to switch the second switch and connect the capacitor and the wavelength tunable interference filter after the signal change timing of the drive pulse. It is preferable that the connection of the input end and the output end in one switch and the disconnection of the input end and the output end in the first switch are performed.
In this application example, the reset period in which the input end and output end of the capacitor are connected and the capacitor is short-circuited is set after the signal change timing of the drive pulse and until the second switch is turned on. In such a configuration, the capacitor can be reset before the second switch is turned on. Therefore, when the second switch is turned on, the charge corresponding to the gap amount can be more appropriately accumulated in the capacitor. The amount detection accuracy can be improved.

In the optical module of this application example, the gap detector switches the first switch, the second switch, and the third switch during a period from the signal change timing of the drive pulse to the next signal change timing. It is preferable to do.
In this application example, the first switch, the second switch, and the third switch are switched in the period of the next signal change timing from the signal change timing of the drive pulse. For example, when the drive pulse is a pulse signal having a predetermined cycle, the first switch, the second switch, and the third switch are switched every half cycle. In such a configuration, gap detection can be performed in the shortest time with respect to the change timing of the drive pulse. Therefore, the frequency of detecting the gap amount can be increased, and the adjustment accuracy of the gap amount can be improved.

The optical module of this application example preferably includes a microcomputer that controls the voltage output unit, and the boosting circuit boosts the reference voltage input from the microcomputer.
In this application example, the booster circuit boosts the reference voltage input from the microcomputer. In such a configuration, for example, a voltage supplied from a power supply device provided separately in the optical module or the peripheral device can suppress voltage fluctuations and adjust the gap amount more accurately than when the gap changing unit is driven. Can be improved.

In the optical module of the application example, it is preferable that the booster circuit includes a first operational amplifier that amplifies the reference voltage.
In this application example, the booster circuit includes a first operational amplifier that amplifies the reference voltage from the microcomputer. Thereby, the configuration of the booster circuit can be simplified and the manufacturing cost can be reduced.

The optical module of this application example preferably includes a microcomputer that controls the voltage output unit, and the drive pulse is a reference pulse based on a clock frequency of the microcomputer.
In this application example, the booster circuit receives a reference pulse from a microcomputer as a drive pulse. In such a configuration, a microcomputer provided for controlling the voltage output unit can also be used as the drive pulse output unit. Therefore, it is not necessary to separately provide an output unit for outputting a drive pulse in the booster circuit or the optical module, and the configuration of the booster circuit or the optical module can be simplified.

In the optical module according to this application example, the booster circuit includes a first operational amplifier that amplifies the reference voltage, and a second operational amplifier that amplifies the voltage value of the reference pulse, and the first operational amplifier and the second operational amplifier. It is preferable to output a voltage corresponding to the sum of the output values of the operational amplifiers.
In this application example, the booster circuit outputs a voltage corresponding to the sum of the output values of the first operational amplifier that amplifies the reference voltage and the second operational amplifier that amplifies the voltage value of the reference pulse. As a result, an output voltage having a magnitude corresponding to a value obtained by adding the voltage value obtained by amplifying the reference pulse to the voltage value obtained by amplifying the reference voltage can be obtained, and a larger output voltage can be obtained with a simple configuration. it can.

In the optical module of this application example, it is preferable that the booster circuit is a charge pump circuit.
In this application example, by using a charge pump circuit as the booster circuit, for example, the booster circuit can be reduced in size as compared with a case where a booster chopper circuit is used, and thus the optical module can be reduced in size. Moreover, it is easy to provide a booster circuit in the optical module.

  An electronic apparatus according to an application example of the invention includes two reflection films that face each other via a gap between the reflection films, and a wavelength that includes a gap changing unit that changes the gap between the reflection films according to an applied voltage. A variable interference filter, a booster circuit that is driven by a predetermined drive pulse and boosts a reference voltage, a gap detector that detects the gap amount, and a detection value of the gap detector that is driven by the output voltage of the booster circuit And a control unit that controls the voltage output unit, and the gap detector sets the gap amount in a non-fluctuation period in which the voltage of the drive pulse does not vary. It is characterized by detecting.

  In this application example, as in the above application example, the gap detector detects the gap amount in a non-fluctuating period in which the voltage of the drive pulse does not fluctuate. As a result, even if noise corresponding to fluctuations in the drive pulse occurs in the booster circuit, the influence of the noise can be suppressed, the gap amount detection accuracy can be improved, and the gap amount adjustment accuracy can be improved. Can do. Therefore, the electronic device can be driven with high accuracy.

1 is an external view illustrating a schematic configuration of a printer according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating a schematic configuration of the printer according to the embodiment. Sectional drawing which shows schematic structure of the spectrometer of the said embodiment. The figure which shows schematic structure of the filter control part of the said embodiment. The figure which shows schematic structure of the booster circuit of the said embodiment. The figure which shows schematic structure of the gap detector of the said embodiment. The figure which shows operation | movement of the gap detector of the said embodiment. The figure which shows operation | movement of the gap detector of the said embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. A printer 10 (inkjet printer) will be described as an example of an electronic apparatus according to the present invention.
[Schematic configuration of printer]
FIG. 1 is a diagram illustrating an external configuration example of the printer 10 according to the first embodiment. FIG. 2 is a block diagram illustrating a schematic configuration of the printer 10 according to the present embodiment.
As shown in FIG. 1, the printer 10 includes a supply unit 11, a transport unit 12, a carriage 13, a carriage moving unit 14, and a control unit 15 (see FIG. 2). The printer 10 prints an image on the medium A by controlling the units 11, 12, 14 and the carriage 13 based on print data input from an external device 30 such as a personal computer. Further, the printer 10 of the present embodiment performs spectroscopic measurement of an image printed on the medium A, and performs processing based on the measurement result (for example, color calibration processing based on the measurement result of spectroscopic measurement of a color patch for color calibration). I do).
Hereinafter, each configuration of the printer 10 will be specifically described.

The supply unit 11 is a unit that supplies the medium A that is an image formation target (in this embodiment, a white paper surface is exemplified) to the image formation position. The supply unit 11 includes, for example, a roll body 111 (see FIG. 1) around which the medium A is wound, a roll drive motor (not shown), a roll drive wheel train (not shown), and the like. Then, based on a command from the control unit 15, the roll drive motor is rotationally driven, and the rotational force of the roll drive motor is transmitted to the roll body 111 via the roll drive wheel train. As a result, the roll body 111 rotates and the paper surface wound around the roll body 111 is supplied downstream (+ Y direction) in the Y direction (sub-scanning direction).
In the present embodiment, an example in which the paper surface wound around the roll body 111 is supplied is shown, but the present invention is not limited to this. For example, the medium A may be supplied by any supply method such as supplying the medium A such as a sheet of paper loaded on a tray or the like one by one with a roller or the like.

The transport unit 12 transports the medium A supplied from the supply unit 11 along the Y direction. The transport unit 12 includes a transport roller 121, a transport roller 121, a driven roller (not shown) that is driven by the transport roller 121, and a platen 122.
The conveyance roller 121 is driven by a conveyance motor (not shown), and when the conveyance motor is driven under the control of the control unit 15, the conveyance roller 121 is rotationally driven by the rotation force, and the medium A is moved between the conveyance roller 121 and the driven roller. It is transported along the Y direction while being sandwiched. A platen 122 facing the carriage 13 is provided on the downstream side (+ Y side) in the Y direction of the transport roller 121.

The carriage 13 includes a printing unit 16 that prints an image on the medium A, and a spectroscope 17 that performs spectroscopic measurement of a predetermined measurement region R (see FIG. 3) on the medium A.
The printing unit 16 is a so-called inkjet head that forms an image by ejecting ink from nozzles formed on the lower surface (surface facing the medium A), for example. The printing unit 16 includes, for example, an ink cartridge 161 corresponding to a plurality of colors of ink, a pressure chamber provided in each nozzle and supplied with ink from the corresponding color ink cartridge 161, and a piezoelectric element provided in the pressure chamber. Ink dots are formed on the medium A by ink droplets ejected from the nozzles by driving the piezo elements.
As will be described in detail later, the spectroscope 17 is a wavelength variable interference filter 5 that transmits light having a wavelength corresponding to the gap amount between the pair of reflective films, and a filter control unit 18 that controls the gap amount of the wavelength variable interference filter. And corresponds to an optical module.

The carriage 13 is provided by a carriage moving unit 14 so as to be movable along a main scanning direction (one direction in the present invention, which is the X direction) crossing the Y direction.
Further, the carriage 13 is connected to the control unit 15 by a flexible circuit 131, and based on a command from the control unit 15, printing processing (image forming processing for the medium A) by the printing unit 16 and spectroscopic measurement processing by the spectroscope 17. To implement.

The carriage moving unit 14 constitutes a moving mechanism in the present invention, and reciprocates the carriage 13 along the X direction based on a command from the control unit 15.
The carriage moving unit 14 includes, for example, a carriage guide shaft 141, a carriage motor 142, and a timing belt 143.
The carriage guide shaft 141 is disposed along the X direction, and both ends are fixed to, for example, a casing of the printer 10. The carriage motor 142 drives the timing belt 143. The timing belt 143 is supported substantially parallel to the carriage guide shaft 141, and a part of the carriage 13 is fixed. When the carriage motor 142 is driven based on a command from the control unit 15, the timing belt 143 travels forward and backward, and the carriage 13 fixed to the timing belt 143 is guided by the carriage guide shaft 141 and reciprocates.

The control unit 15 corresponds to a module control unit, and includes an I / F 151, a unit control circuit 152, a memory 153, and a CPU (Central Processing Unit) 154 as shown in FIG.
The I / F 151 inputs print data input from the external device 30 to the CPU 154.
The unit control circuit 152 includes control circuits that respectively control the supply unit 11, the transport unit 12, the carriage movement unit 14, the printing unit 16, the spectroscope 17, and the filter control unit 18 based on a command signal from the CPU 154. Each unit 11 to 18 is controlled based on a command signal from the CPU 154. The control circuit may be provided separately from the control unit 15 and connected to the control unit 15.

  The memory 153 stores various programs and various data for controlling the operation of the printer 10. Examples of the various data include print profile data that stores the ejection amount of each ink with respect to color data included as print data. Moreover, the light emission characteristic with respect to each wavelength of the light source part 171 and the light reception characteristic (light reception sensitivity characteristic) with respect to each wavelength of the light-receiving part 173 may be memorize | stored.

  The CPU 154 reads out and executes various programs stored in the memory 153, thereby controlling the driving of the supply unit 11, the transport unit 12, and the carriage moving unit 14, the printing control of the printing unit 16, and the spectroscopic measurement control of the spectrometer 17. And processing (color calibration processing etc.) based on the measurement data by the spectroscope 17 is performed.

[Configuration of spectrometer]
FIG. 3 is a cross-sectional view showing a schematic configuration of the spectrometer 17.
As shown in FIG. 3, the spectroscope 17 includes a light source unit 171, an optical filter device 172 including the variable wavelength interference filter 5, a light receiving unit 173, a light guide unit 174, and a filter control unit 18 (see FIG. 2). And.
The spectroscope 17 irradiates illumination light onto the medium A from the light source unit 171, and causes the light component reflected by the medium A to enter the optical filter device 172 through the light guide unit 174. Then, the optical filter device 172 emits (transmits) light having a predetermined wavelength from the reflected light and causes the light receiving unit 173 to receive the light. Further, the optical filter device 172 can select a transmission wavelength (emission wavelength) based on the control of the control unit 15, and measures the light amount of each wavelength in visible light, thereby measuring the measurement region on the medium A. R spectroscopic measurement is possible.

[Configuration of light source unit, light receiving unit, and light guide optical system]
The light source unit 171 includes a light source 171A and a light collecting unit 171B. The light source unit 171 irradiates the light emitted from the light source 171 </ b> A into the measurement region R of the medium A from the normal direction to the surface of the medium A.
The light source 171A is preferably a light source that can emit light of each wavelength in the visible light region. As such a light source 171A, for example, a halogen lamp, a xenon lamp, a white LED, and the like can be exemplified, and in particular, a white LED that can be easily installed in a limited space in the carriage 13 is preferable. The condensing unit 171B is configured by, for example, a condensing lens and condenses light from the light source 171A on the measurement region R. In FIG. 3, the condensing unit 171B displays only one lens (condensing lens), but may be configured by combining a plurality of lenses.

  The light receiving unit 173 is disposed on the optical axis of the wavelength variable interference filter 5 and receives light transmitted through the wavelength variable interference filter 5. The light receiving unit 173 outputs a detection signal (current value) corresponding to the amount of received light based on the control of the control unit 15. The detection signal output by the light receiving unit 173 is input to the control unit 15 via an IV converter (not shown), an amplifier (not shown), and an AD converter (not shown).

The light guide unit 174 includes a reflecting mirror 174A and a band pass filter 174B.
The light guide unit 174 reflects the light reflected at 45 ° with respect to the surface of the medium A in the measurement region R onto the optical axis of the wavelength variable interference filter 5 by the reflecting mirror 174A. The band-pass filter 174B transmits light in the visible light range (for example, 380 nm to 720 nm) and cuts ultraviolet light and infrared light. As a result, light in the visible light region is incident on the wavelength variable interference filter 5, and light having a wavelength selected by the wavelength variable interference filter 5 in the visible light region is received by the light receiving unit 173.

[Configuration of optical filter device]
FIG. 4 is a diagram schematically illustrating the wavelength variable interference filter 5 and the filter control unit 18 included in the spectrometer 17.
As shown in FIG. 4, the optical filter device 172 includes a housing 6 and a wavelength variable interference filter 5 housed in the housing 6.
(Configuration of wavelength variable interference filter)
The tunable interference filter 5 is a tunable Fabry-Perot etalon element, and includes a translucent fixed substrate 51 and a movable substrate 52 as shown in FIG. By being bonded by the bonding film, it is configured integrally.
In addition, the wavelength variable interference filter 5 includes a fixed reflection film 54 and a movable reflection film 55 that are arranged to face each other via a gap G (a gap between reflection films), and an electrostatic actuator 56 that adjusts the size (gap amount) of the gap G. And comprising.

(Configuration of fixed substrate)
The fixed substrate 51 is provided with a fixed reflective film 54 and a fixed electrode 561 that constitutes the electrostatic actuator 56 on a surface facing the movable substrate 52. The fixed substrate 51 is formed to have a thickness larger than that of the movable substrate 52, and the fixed substrate 51 has an electrostatic attraction when a voltage is applied to the electrostatic actuator 56 or an internal stress of the fixed electrode 561 described later. There is no deflection.

The fixed reflection film 54 is provided at the center position of the groove provided in the fixed substrate 51. The fixed reflective film 54 is connected to a gap detector 21 described later of the filter control unit 18. In the present embodiment, the fixed reflection film 54 and the movable reflection film 55 constitute a gap detection capacitor. As the fixed reflection film 54, for example, a metal film such as Ag or a conductive alloy film such as an Ag alloy can be used. For example, a dielectric multilayer film in which the high refractive layer is TiO ₂ and the low refractive layer is SiO ₂ may be used. In this case, a conductive metal alloy film is formed on the lowermost layer or the surface layer of the dielectric multilayer film. Thus, the fixed reflective film 54 can be functioned as an electrode of a capacitor for gap detection.

  The fixed electrode 561 is formed in a substantially arc shape surrounding the fixed reflection film 54 in a plan view as viewed from the thickness direction of the fixed substrate 51. The fixed electrode 561 is connected to a feedback control unit 181 described later of the filter control unit 18.

(Configuration of movable substrate)
The movable substrate 52 includes a movable portion 521 and a holding portion 522 that is provided outside the movable portion 521 and holds the movable portion 521.
The movable part 521 has a thickness dimension larger than that of the holding part 522. The movable portion 521 is provided with a movable reflective film 55 and a movable electrode 562 that constitutes the electrostatic actuator 56.

  The movable reflective film 55 is provided at the center of the surface of the movable portion 521 facing the fixed substrate 51 so as to face the fixed reflective film 54 with a gap G interposed therebetween. The movable reflective film 55 is connected to a gap detector 21 (to be described later) of the filter control unit 18, and constitutes a gap detection capacitor together with the fixed reflective film 54. As the movable reflective film 55, a reflective film having the same configuration as that of the fixed reflective film 54 described above is used.

  The movable electrode 562 faces the fixed electrode 561 with a predetermined gap. The movable electrode 562 is connected to the feedback control unit 181.

The holding part 522 is a diaphragm that surrounds the periphery of the movable part 521, and has a thickness dimension smaller than that of the movable part 521. Such a holding part 522 is easier to bend than the movable part 521, and the movable part 521 can be displaced toward the fixed substrate 51 by a slight electrostatic attraction. As a result, the gap amount of the gap G can be changed while maintaining the parallelism of the fixed reflective film 54 and the movable reflective film 55.
In the present embodiment, the diaphragm-like holding part 522 is illustrated, but the present invention is not limited to this. For example, a configuration in which beam-like holding parts arranged at equiangular intervals around the plane center point are provided. It is good.

(Case configuration)
As shown in FIG. 4, the housing 6 includes a base 61 and a lid 62. The base 61 and the lid 62 are bonded by, for example, low melting point glass bonding using glass frit (low melting point glass), adhesion by an epoxy resin or the like. Thereby, an accommodation space is formed inside, and the wavelength variable interference filter 5 is accommodated in the accommodation space.

The base 61 is formed by, for example, laminating ceramics on a thin plate, and has a recess 611 that can accommodate the wavelength variable interference filter 5. The wavelength variable interference filter 5 is fixed to the bottom surface of the recess 611 of the base 61 by, for example, a fixing material. A light passage hole 612 is provided on the bottom surface of the recess 611 of the base 61. The light passage hole 612 is provided so as to include a region overlapping the reflective films 54 and 55 of the wavelength variable interference filter 5. Further, a cover glass 613 is joined to the base 61 so as to cover the light passage hole 612.
The lid 62 is a glass flat plate and is joined to an end surface opposite to the bottom surface of the base 61.

[Configuration of filter control unit]
The filter control unit 18 corresponds to a voltage control unit, and includes a feedback control unit 181, a microcomputer (microcontroller) 19, a booster circuit 20, and a gap detector 21, as shown in FIG.
Based on the detection result obtained by detecting the size (gap amount) of the gap G of the wavelength tunable interference filter 5 by the gap detector 21, the filter control unit 18 sets a value based on the wavelength setting command from the unit control circuit 152 (to the target wavelength). Set the gap amount to the corresponding value. That is, the filter control unit 18 adjusts the drive voltage of the electrostatic actuator 56 based on the detection result of the gap amount and the wavelength setting command so that the wavelength of the transmitted light of the wavelength variable interference filter 5 becomes the target wavelength. The dimension of the gap G is set.

(Configuration of feedback control unit)
The feedback control unit 181 corresponds to a voltage output unit, modulates the output voltage V _out from the booster circuit 20 based on a target command for setting the gap G input from the microcomputer 19 to a predetermined target value, A drive voltage (applied voltage) is applied to the electrostatic actuator 56.
Specifically, as illustrated in FIG. 4, the feedback control unit 181 is connected to the fixed electrode 561 and the movable electrode 562 of the wavelength variable interference filter 5. The feedback control unit 181 then adjusts the output voltage _Vout so that the deviation between the target command signal (voltage value) from the microcomputer 19 and the detection signal (voltage value) from the gap detector 21 is equal to or less than a predetermined threshold value. A feedback control is performed to modulate and adjust the drive voltage of the electrostatic actuator 56.

  Although not shown, the feedback control unit 181 includes, for example, a PID (Proportional-Integral-Differential) controller, a drive circuit, and the like. The PID controller performs feedback control so that the deviation between the command signal and the detection signal is less than or equal to a predetermined threshold, and outputs a feedback signal corresponding to the detection signal. The drive circuit is configured to modulate the output voltage from the booster circuit 20 based on the feedback signal and to output a DC drive voltage.

(Microcomputer configuration)
The microcomputer 19 includes a storage unit 191 and stores, for example, a relationship (gap correlation data) between a detection signal (voltage value) detected by the gap detector 21 and the size of the gap G. As shown in FIG. 4, the microcomputer 19 functions as a reference voltage output unit 192, a reference signal output unit 193, a gap detection control unit 194, and a feedback command unit 195.

  The reference voltage output unit 192 outputs a predetermined reference voltage to the booster circuit 20. Although not shown, the reference voltage output unit 192 includes, for example, a power supply circuit that outputs a reference voltage, a stabilization circuit that suppresses fluctuations in the reference voltage, and the like provided in the microcomputer 19.

  The reference signal output unit 193 generates a reference signal that is a rectangular wave pulse signal having a predetermined frequency based on the clock frequency of the microcomputer 19, and outputs the reference signal to the booster circuit 20. That is, the reference signal corresponds to a drive pulse and a reference pulse. Although not shown, the reference signal output unit 193 is configured by, for example, an oscillation circuit or a frequency divider provided in the microcomputer 19.

  The gap detection control unit 194 controls the gap detector 21 based on the reference signal output from the reference signal output unit 193. In the present embodiment, as will be described in detail later, the gap detection control unit 194 causes the gap detector 21 to detect the size of the gap G in a non-change period in which the voltage of the reference signal that is a rectangular wave pulse signal does not change. Note that the non-variation period is a period between the rising timing and falling timing of the reference signal.

  The feedback command unit 195 outputs a target command for setting the gap G to a predetermined target value to the feedback control unit 181. Specifically, the feedback command unit 195 calculates a target value corresponding to the target wavelength based on the setting command from the unit control circuit 152 and the gap correlation data, and feeds back the target command corresponding to the target value. The data is output to the control unit 181.

(Configuration of booster circuit)
FIG. 5 is a diagram schematically showing the configuration of the booster circuit 20.
The booster circuit 20 receives the reference voltage Vo and the reference signal So from the microcomputer 19, and outputs an output voltage Vout obtained by amplifying the reference voltage Vo based on the reference signal So to the feedback control unit 181.
In the present embodiment, the booster circuit 20 includes a first non-inverting amplifier circuit 201, a second non-inverting amplifier circuit 202, a smoothing capacitor Cs, a flying capacitor Cfa, an output capacitor Co, a first diode D1, And a charge pump circuit including two diodes D2.

The first non-inverting amplifier circuit 201 includes a first operational amplifier OP1, amplifies a predetermined reference voltage Vo input from the microcomputer 19 to the first operational amplifier OP1 with a predetermined amplification degree, and outputs a first voltage V1 (DC voltage). ) Is output.
The smoothing capacitor Cs is connected to the output side of the first non-inverting amplifier circuit 201 and is applied with the first voltage V1.

  The second non-inverting amplifier circuit 202 includes a second operational amplifier OP2, amplifies the reference signal So input from the microcomputer 19 to the second operational amplifier OP2 with a predetermined amplification degree, and outputs a second voltage V2. The second voltage V2 is a rectangular wave voltage having a predetermined frequency according to the frequency of the reference signal So.

The flying capacitor Cfa is connected to the output side of the second non-inverting amplifier circuit 202. The flying capacitor Cfa is connected to the output side of the first non-inverting amplifier circuit 201 via the first diode D1, and a voltage corresponding to the first voltage V1 is applied at a timing according to the reference signal So. The
The output capacitor Co is connected to the output side of the second non-inverting amplifier circuit 202 via the flying capacitor Cfa and the second diode D2.

A boosting operation by the boosting circuit 20 configured as described above will be described.
The first non-inverting amplifier circuit 201 applies the first voltage V1 obtained by amplifying the reference voltage Vo to the smoothing capacitor Cs. The second non-inverting amplifier circuit 202 amplifies the reference signal So from the microcomputer 19 and outputs the second voltage V2. When the reference signal So is Low, the first voltage V1 is applied to the flying capacitor Cfa via the first diode D1. When the reference signal So is High, the voltage obtained by adding the voltage of the flying capacitor Cfa to the second voltage V2 _pp that is the output of the second non-inverting amplifier circuit 202 is output via the second diode D2 to the output capacitor Co2. To be applied. The voltage applied to the output capacitor Co is the output voltage V _out of the booster circuit 20. The output voltage _Vout is calculated by the following equation (1).
_V2pp is the difference between the maximum value and the minimum value of the second voltage V2, and is the maximum value of the second voltage V2 in this embodiment. In the following formula (1), Vf is a forward voltage of the first diode D1 and the second diode D2.

[Equation 1]
V _out = V 1 + V 2 _pp −2 × Vf (1)

For example, the reference voltage Vo is 1V, the amplification factor of the first operational amplifier OP1 is 22 times, the voltage when the reference signal So is High is 5V, the amplification factor of the second operational amplifier OP2 is 4 times, and the first diode D1 and the first diode D1 The voltage Vf of the two diodes D2 is 0.6V. In this case, the output voltage V _out calculated based on the above equation (1) is 40.8V. Here, the amplitude of the drive voltage of the variable wavelength interference filter 5 is, for example, 20V to 40V. Therefore, the booster circuit 20 can boost the reference voltage Vo and output an output voltage _Vout that is large enough to drive the variable wavelength interference filter 5.

(Gap detector configuration)
FIG. 6 is a diagram schematically showing the configuration of the gap detector 21. FIG. 7 is a timing chart schematically showing the operation of the gap detector 21.
As shown in FIG. 6, the gap detector 21 includes a capacitance detection circuit 211, a subtraction circuit 212, and a sample and hold circuit 213. The gap detector 21 is driven by the output voltage V _out of the booster circuit 20 and feeds back a detection signal (DC voltage) corresponding to the capacitance Cx between the reflective films 54 and 55 at a timing corresponding to the reference signal So. The data is output to the control unit 181.

  Here, the capacitance Cx is a capacitance of a capacitor constituted by the fixed reflection film 54 and the movable reflection film 55 and has a relationship corresponding to the gap amount. Therefore, the gap amount can be detected based on the capacitance Cx. In the present embodiment, when detecting the gap amount, a bias voltage (Vb−Va) is applied between the fixed reflective film 54 and the movable reflective film 55 by a bias power source (not shown). At this time, charges corresponding to the bias voltage (Vb−Va) and the capacitance Cx are accumulated between the reflective films 54 and 55. The first bias voltage Va is smaller than the second bias voltage Vb.

The capacitance detection circuit 211 includes an operational amplifier OP3, a feedback capacitor Cfb, and switches SW1 to SW3. The capacitance detection circuit 211 converts the capacitance Cx between the reflection films 54 and 55 to the voltage Vc at a timing according to the reference signal So. And the voltage Vc is output. Hereinafter, the voltage Vc is also referred to as a conversion voltage Vc.
The switches SW1 to SW3 are switched between connection (on) and disconnection (off) based on a control signal from the gap detection control unit 194. These switches SW1 to SW3 are constituted by transistors or MOSFETs (metal-oxide-semiconductor field-effect transistors).

The switch SW1 switches between an on state in which the bias voltage (Vb−Va) is applied to each of the reflective films 54 and 55 and an off state in which the bias voltage (Vb−Va) is not applied.
The switch SW2 corresponds to the first switch, and switches connection and disconnection between the input end and the output end of the feedback capacitor Cfb. That is, the switch SW2 is initialized by short-circuiting the feedback capacitor Cfb in the ON state. A period during which the switch SW2 is in the ON state (High) is also referred to as a reset period T1 (see FIG. 7).

  The switch SW3 corresponds to a second switch, and switches connection and disconnection between the variable wavelength interference filter 5 and the feedback capacitor Cfb. That is, the switch SW3 switches between an on state in which one of the reflection films 54 and 55 constituting the gap detection capacitor to which the bias voltage is applied and the feedback capacitor Cfb are connected, and an off state in which the switch is disconnected. In the ON state of the switch SW3, the electric charge accumulated between the reflecting films 54 and 55 is transferred to the feedback capacitor Cfb.

  Further, the switch SW3 has an ON state in which one of the reflection films 54 and 55 constituting the gap detection capacitor to which a bias voltage is applied and the negative terminal of the operational amplifier OP3 are connected, and a disconnected OFF state. Switch. In the ON state of the switch SW3, the conversion voltage Vc is output from the capacitance detection circuit 211. That is, the period during which the switch SW3 is turned on is the conversion period T2 in which the capacitance Cx is converted into the conversion voltage Vc. Note that the peak voltage Vcp of the conversion voltage Vc can be calculated by the following equation (2).

[Equation 2]
Vcp = {(Vb−Va) × Cx / Cf} + Vb (2)

  The subtraction circuit 212 is provided on the output side of the capacitance detection circuit 211, and outputs a voltage Vd obtained by subtracting the second bias voltage Vb from the conversion voltage Vc in the conversion period T2 in which the switch SW3 is turned on. This voltage Vd is input to the sample and hold circuit 213. Hereinafter, the voltage Vd is also referred to as the input voltage Vd. The peak voltage Vdp value of the input voltage Vd can be calculated by the following equation (3).

[Equation 3]
Vdp = (Vb−Va) × Cx / Cf (3)

The sample and hold circuit 213 is provided on the output side of the subtraction circuit 212 via the switch SW4, and outputs the detection voltage Ve from the gap detector 21.
The switch SW4 corresponds to a third switch, is configured in the same manner as the switches SW1 to SW3, and is switched between connection and disconnection based on a control signal from the gap detection control unit 194. In this embodiment, the switch SW4 is turned on in a predetermined period (hereinafter also referred to as a detection period T3) within a period in which the input voltage Vd becomes the peak voltage Vdp, as shown in FIG. The sample and hold circuit 213 detects the peak voltage Vdp in the detection period T3 and outputs a detection voltage Ve that is a DC voltage. The magnitude of the detection voltage Ve is the peak voltage Vdp.

FIG. 8 is a timing chart schematically showing a gap amount detection operation performed based on the reference signal So in the gap detector 21 described above.
Here, in the booster circuit 20, the transition (reverse recovery) from the conduction state to the blocking state occurs in the first diode D1 at the rising timing of the reference signal So. Further, at the fall timing of the reference signal So, the second diode D2 transitions from the conduction state to the blocking state. Therefore, in the booster circuit 20, noise is generated due to resonance caused by the inductor component of the wiring and the capacitance components of the diodes D <b> 1 and D <b> 2 at the rising or falling timing of the reference signal So. On the other hand, in the present embodiment, as shown in FIG. 8, the gap detector 21 includes a non-fluctuation period T4 in which the voltage of the reference signal So does not change, that is, a rising period in which the reference signal So is High, and the reference signal The state detection operation is performed in the falling period when So is Low. Thereby, the gap detector 21 can suppress the influence of the noise, and can detect the detection voltage Ve corresponding to the size of the gap G of the variable wavelength interference filter 5 with high accuracy.

  Specifically, as shown in FIG. 8, in a predetermined reset period T1 from the rising and falling timings of the reference signal So, the switch SW2 is turned on, and the feedback capacitor Cfb is short-circuited and initialized. In the reset period T1, the switch SW1 is turned on, and a bias voltage (Vb−Va) is applied between the reflective films 54 and 55. The reset period T1 is set between the change timing (rise timing and fall timing) of the reference signal So and the start timing of the conversion period T2.

  Next, in the conversion period T2 following the reset period T1, the switch SW1 and the switch SW2 are turned off and the switch SW3 is turned on, and the electric charge accumulated between the reflecting films 54 and 55 is transferred to the feedback capacitor Cfb. . The peak voltage Vcp of the conversion voltage Vc output from the capacitance detection circuit 211 at this time is a value represented by the above formula (2). In the conversion period T2, the peak voltage Vdp of the input voltage Vd output from the subtraction circuit 212 is a value represented by the above equation (3).

  Here, in a predetermined detection period T3 in the conversion period T2, the switch SW4 is turned on, and the peak voltage Vdp is input to the sample and hold circuit 213. The sample and hold circuit 213 converts the input peak voltage Vdp into a DC voltage and outputs a detection voltage Ve. The sample and hold circuit 213 outputs a constant detection voltage Ve until the next detection period T3.

  In the present embodiment, the reset period T1 and the conversion period T2 are set within the non-variation period T4. The detection period T3 is set within the conversion period T2. That is, the period of the reference signal So is set to be twice the repetition period of the reset period T1 (conversion period T2), and the start timing of the reset period T1 is synchronized with the rising and falling timings of the reference signal So. ing. Therefore, in the conversion period T2 and the detection period T3, the booster circuit 20 is not switched, and the influence of switching noise is suppressed.

  In addition, before and after the detection period T3, a margin is set for the start timing and end timing of the conversion period T2. Thereby, the detection period T3 can be started after the start of the conversion period T2, and the detection period T3 can be ended before the end of the conversion period T2. Therefore, the detection accuracy in the sample and hold circuit 213 can be improved.

  Note that the margin on the front side of the detection period T3 is set to be equal to or longer than the time (stabilization time) in which the value of the input voltage Vd is stabilized at the peak voltage Vdp from the start of the conversion period T2, for example. Thereby, it is possible to suppress the input voltage Vd from being input to the sample and hold circuit 213 at the timing when the input voltage Vd varies, and the detection accuracy of the detection voltage Ve can be improved.

  Further, the margin on the rear side of the detection period T3 is set to be larger than the fluctuation range of the end timing of the conversion period T2 due to, for example, malfunction of the switch SW3. As a result, even if the switch SW3 is turned off before the predetermined timing and the conversion period T2 is ended due to the malfunction, the detection period T3 can be ended before the end of the conversion period T2. Ve detection accuracy can be improved.

The conversion period T2 is set longer than the reset period T1. Thereby, in the non-variation period T4, the conversion period T2 can be set longer, and the margin before and after the detection period T3 in the conversion period T2 can be set longer.
Note that the length of the conversion period T2 may be the same as the reset period T1, or may be shorter than the reset period T1.

[Effects of Embodiment]
In the present embodiment, the following operational effects can be obtained.
The feedback control unit 181 is driven by the output voltage _Vout from the booster circuit 20 that is driven based on the reference signal So, and the applied voltage to the electrostatic actuator 56 is determined based on the detected value of the gap amount of the gap detector 21. Output. The gap detector 21 detects the gap amount during the non-change period T4 in which the voltage of the reference signal So does not change. In such a configuration, even if noise corresponding to a change in the reference signal So occurs in the booster circuit 20 driven by the predetermined reference signal So, the influence of the noise can be suppressed, and the gap amount detection accuracy is improved. Can be made. Therefore, the adjustment accuracy of the gap amount can be improved.

  The gap detector 21 switches the switch SW4 during the non-change period T4 of the reference signal So. Thereby, since the reference signal So does not change in the detection period T3 in which the sample and hold circuit 213 detects the voltage, the influence of the noise in the detection period T3 can be suppressed.

  Further, since the gap detector 21 switches the switch SW3 during the non-fluctuation period T4, the influence of the noise can be suppressed when the electric charge corresponding to the gap amount is accumulated in the feedback capacitor Cfb. Therefore, the amount of charge accumulated in the feedback capacitor Cfb, that is, the voltage of the feedback capacitor Cfb can be set to an appropriate value according to the gap amount, and the detection accuracy of the gap amount can be improved.

  The reset period T1 in the gap detector 21 is after the signal change timing (rise timing and fall timing) of the reference signal So and until the switch SW3 is turned on, that is, from the start timing of the conversion period T2. Is also set before. Thereby, the feedback capacitor Cfb can be reset before the start of the conversion period T2. Therefore, in the conversion period T2, charges corresponding to the gap amount can be accumulated in the feedback capacitor Cfb, and the detection accuracy of the gap amount can be improved.

  The gap detector 21 switches the switches SW1 to SW4 in the period of the next signal change timing from the signal change timing of the reference signal So. That is, the switches SW1 to SW4 are switched every half cycle of the reference signal So that is a pulse signal having a predetermined cycle. In such a configuration, the gap detector 21 can detect the gap in the shortest time with respect to the change timing of the reference signal So. Therefore, the frequency of detecting the gap amount can be increased, and the adjustment accuracy of the gap amount can be improved.

Here, when a power supply device is separately provided in the spectroscope 17 or the control unit 15 and the electrostatic actuator 56 is driven by the voltage supplied from the power supply device, the supply voltage from the power supply device fluctuates and the gap amount There was a risk that the adjustment accuracy would decrease.
On the other hand, the booster circuit 20 boosts the reference voltage Vo input from the microcomputer 19. The feedback control unit 181 is driven by the output voltage V _out of the booster circuit 20. Thereby, the voltage fluctuation of the drive voltage of the electrostatic actuator 56 can be suppressed, and the adjustment accuracy of the gap amount can be improved.
Further, the booster circuit 20 includes a first operational amplifier OP1 that amplifies the reference voltage Vo from the microcomputer 19. As a result, the configuration of the booster circuit 20 can be simplified and the manufacturing cost can be reduced.

  The booster circuit 20 is driven based on the reference signal So input from the microcomputer 19. In such a configuration, the microcomputer 19 provided for controlling the feedback control unit 181 can also be used as the output unit of the reference signal So. Therefore, it is not necessary to separately provide an output unit for outputting the reference signal So in the booster circuit 20 or the spectroscope 17, and the configuration of the booster circuit 20 or the spectroscope 17 can be simplified.

The booster circuit 20 outputs an output voltage _Vout corresponding to the sum of the output values of the first operational amplifier OP1 that amplifies the reference voltage Vo and the second operational amplifier OP2 that amplifies the voltage value of the reference signal So. As a result, an output voltage _Vout having a magnitude corresponding to a value obtained by adding the voltage value obtained by amplifying the reference signal So to the voltage value obtained by amplifying the reference voltage Vo can be obtained. V _out can be obtained.

Here, for example, when a boost chopper circuit is used as the booster circuit 20, it is difficult to reduce the size of the booster circuit 20, and it is not easy to mount the booster circuit 20 in the spectrometer 17.
On the other hand, in this embodiment, by using the charge pump circuit configured as described above as the booster circuit 20, the booster circuit 20 can be reduced in size, and as a result, the filter control unit 18 can be reduced in size. You can plan. It is also easy to provide the booster circuit 20 in the spectrometer 17.

[Modification]
It should be noted that the present invention is not limited to the above-described embodiments and modifications, and includes a configuration obtained by appropriately combining modifications, improvements, and embodiments within a range in which the object of the present invention can be achieved. It is what
In the above embodiment, the case where a pulse signal having a predetermined period having a rising period and a falling period having the same length is used as the reference signal So is exemplified, but the present invention is not limited to this. For example, the rising period and the falling period may have different lengths.

  In the above embodiment, the gap detector 21 is driven in synchronization with the booster circuit 20 by detecting the gap amount during the non-fluctuation period T4 of the reference signal So based on the control by the microcomputer 19, but this It is not limited to. For example, the gap detector 21 may include a switch control unit that switches connection and disconnection of the switches SW <b> 1 to SW <b> 4 based on the reference signal So from the microcomputer 19.

  In the gap detector 21 of the above-described embodiment, the reset period T1, the conversion period T2, and the detection period for each non-variation period T4 of the reference signal So, that is, for each of the rising period and the falling period of the reference signal So. Although the period T3 is set, the present invention is not limited to this. For example, at least the detection period T3 may be set to the non-variation period T4. In this case, in the detection period T3 in which the sample and hold circuit 213 detects the voltage, the influence of noise due to the change in the reference signal So can be suppressed, and the gap amount detection accuracy can be improved.

  Further, the end timing of the reset period T1 and the start timing of the conversion period T2 are set within the non-change period T4, and the detection period T3 is between the start timing of the conversion period T2 and the end timing of the non-change period T4. It may be set. That is, the reset period T1 may be set so as to straddle the start timing of the non-fluctuation period T4, and the conversion period T2 may be set so as to straddle the end timing of the non-fluctuation period T4. Even in such a configuration, the gap detector 21 can initialize the feedback capacitor Cfb and detect the gap amount in the non-variation period T4, and can improve the accuracy of detecting the gap amount.

  When the reset period T1, the conversion period T2, and the detection period T3 are set for each of the non-variation periods T4, the detection period T3 can be set by setting a margin before and after the reset period T1 and the conversion period T2. Period is shortened. For this reason, it may be difficult to set a detection period T3 having a sufficient length for detecting the gap amount. On the other hand, the margin can be reduced by setting the reset period T1 and the conversion period T2 so as to straddle the continuous non-change period T4. Therefore, the detection period T3 can be lengthened, and the setting of the detection period T3 is easy.

  Further, although the detection period T3 is set in advance in the non-change period T4, the present invention is not limited to this. For example, a voltage detector that detects that the input voltage Vd input to the sample and hold circuit has reached the peak voltage Vdp is provided, and the detection period T3 is started based on the detection result of the peak voltage Vdp by the voltage detector You may let them. Thereby, it is possible to suppress the start of the detection period T3 before the input voltage Vd reaches the peak voltage Vcp. It may be detected that the converted voltage Vc from the capacitance detection circuit has reached the peak voltage Vcp.

In the above embodiment, the gap detector 21 is driven by the output voltage _Vout from the booster circuit 20, but the present invention is not limited to this, and the gap detector 21 may be driven by power supplied from a separately provided power supply device. . In this case, even if noise is generated in the booster circuit 20, the gap detector 21 detects the gap amount in the non-fluctuation period T4, so that the influence of the noise can be suppressed.

  In the above embodiment, the charge pump circuit including the first non-inverting amplifier circuit 201 that amplifies the reference voltage Vo from the microcomputer 19 and the second non-inverting amplifier circuit 202 that amplifies the reference signal So is used as the booster circuit 20. Although illustrated, it is not limited to this. For example, the booster circuit 20 does not include the second non-inverting amplifier circuit 202 that amplifies the reference signal So but includes at least a first non-inverting amplifier circuit 201 that amplifies the reference voltage Vo, and the first non-inverting amplifier circuit 201 is based on the reference signal So. A charge pump circuit that boosts the output voltage of the inverting amplifier circuit 201 may be used.

In the above embodiment, the booster circuit 20 has exemplified the configuration for boosting the reference voltage Vo from the microcomputer 19, but it may boost the supply voltage from a separately provided power supply device.
Further, the booster circuit 20 is driven based on the reference signal So input from the microcomputer 19, but is not limited to this. For example, the booster circuit 20 may be driven based on a drive pulse from a signal generator provided separately. In this case, the gap detector 21 detects the gap amount during the non-fluctuation period of the drive pulse output from the signal generator.

  In the above embodiment, the charge pump circuit is exemplified as the booster circuit 20, but the present invention is not limited to this, and various booster circuits driven based on a predetermined drive pulse such as a boost chopper circuit can be used.

In the embodiment described above, the filter control unit 18 uses the feedback control unit 181 that adjusts the drive voltage based on the detected value of the gap amount by the gap detector 21 as the voltage output unit that outputs the drive voltage of the variable wavelength interference filter 5. Although provided, it is not limited to this.
For example, the filter control unit 18 does not include the gap detector 21, modulates the output voltage V _out from the booster circuit 20 based on the target command from the microcomputer 19, and outputs the drive voltage of the wavelength variable interference filter 5. You may be set as the structure provided with a voltage output part. Even in such a configuration, as described above, by providing the booster circuit 20 that boosts the reference voltage Vo from the microcomputer 19 and outputs the output voltage _Vout , fluctuations in the drive voltage can be suppressed.

In the above embodiment, the electrostatic actuator for feedback control is exemplified as the electrostatic actuator, but the present invention is not limited to this. For example, in addition to the electrostatic actuator for feedback control, a second electrostatic actuator that is driven with a predetermined drive voltage according to the target command may be provided. When the second electrostatic actuator is provided, for example, the filter control unit 18 may be provided with a second voltage output unit that applies a second drive voltage corresponding to the target command to the second electrostatic actuator. . For example, by using the second electrostatic actuator as an electrostatic actuator for coarse movement with a large driving amount and using the electrostatic actuator for feedback control as an electrostatic actuator for fine movement with a small driving amount, the gap amount can be reduced. Adjustment accuracy can be further improved.
Further, in this case, by driving the second voltage output unit with the output voltage _Vout from the booster circuit 20, fluctuations in the second drive voltage can be suppressed.

In each of the embodiments described above, the wavelength variable interference filter 5 includes the electrostatic actuator 56 as a gap changing unit that changes the gap between the reflective films, but is not limited thereto.
For example, the wavelength variable interference filter 5 may include a piezoelectric element between the fixed substrate 51 and the movable substrate 52 as a gap changing unit, and the gap amount may be changed by driving the piezoelectric element.
Further, the present invention is not limited to a configuration including two substrates, a fixed substrate 51 and a movable substrate 52. For example, two reflective films are stacked on a single substrate via a sacrificial layer, and the sacrificial layer is removed by etching or the like for reflection. A wavelength variable interference filter in which a gap between films is formed may be used.

In the above embodiment, as the variable wavelength interference filter 5, the light transmission type variable wavelength interference filter 5 that transmits light having a wavelength corresponding to the gap G between the reflection films 54 and 55 from the incident light is illustrated. Not. For example, a light reflection type tunable interference filter that reflects light having a wavelength corresponding to the gap G between the reflection films 54 and 55 may be used.
Further, although the optical filter device 172 in which the wavelength tunable interference filter 5 is housed in the housing 6 is illustrated, a configuration in which the wavelength tunable interference filter 5 is directly provided in the spectroscope 17 may be employed.

In the above-described embodiment, the ink jet type printing unit 16 that drives the piezoelectric element and ejects the ink supplied from the ink tank is exemplified as the printing unit 16, but is not limited thereto. For example, the printing unit 16 may have a configuration in which bubbles are generated in the ink by a heater to discharge the ink, or a configuration in which the ink is discharged by an ultrasonic transducer.
Further, the present invention is not limited to the ink jet type, and can be applied to any printing type printer such as a thermal printer using a thermal transfer method, a laser printer, or a dot impact printer.

  In the said embodiment, although the printer 10 provided with the spectrometer 17 as an optical module was illustrated, it is not limited to this. For example, an uneven color spectroscopic measurement apparatus that does not include an image forming unit and performs only spectroscopic measurement processing on the medium A may be used. Further, for example, the optical module may be incorporated in a quality inspection apparatus that performs quality inspection of printed matter manufactured in a factory or the like, and the optical module of the present invention may be incorporated in any other apparatus.

  In addition, the specific structure for carrying out the present invention may be configured by appropriately combining the above-described embodiment and modification examples within the scope in which the object of the present invention can be achieved, and may be appropriately changed to other structures. May be.

DESCRIPTION OF SYMBOLS 5 ... Wavelength variable interference filter, 10 ... Printer, 17 ... Spectrometer, 18 ... Filter control part, 19 ... Microcomputer, 20 ... Booster circuit, 21 ... Gap detector, 51 ... Fixed substrate, 52 ... Movable substrate, 54 ... Fixed Reflective film, 55 ... movable reflective film, 56 ... electrostatic actuator, 61 ... base, 62 ... lid, 181 ... feedback control unit, 191 ... storage unit, 192 ... reference voltage output unit, 193 ... reference signal output unit, 194 ... Gap detection control unit, 195 ... feedback command unit, 201 ... first non-inverting amplifier circuit, 202 ... second non-inverting amplifier circuit, 211 ... capacitance detection circuit, 212 ... subtraction circuit, 213 ... sample and hold circuit, 512 ... reflection Membrane installation part, 521 ... movable part, 522 ... holding part, 561 ... fixed electrode, 562 ... movable electrode, 611 ... concave part, 612 ... light passage hole 613 ... Cover glass, Cfb ... Feedback capacitor, G ... Gap, OP1 ... First operational amplifier, OP2 ... Second operational amplifier, SW2 ... Switch (first switch), SW3 ... Switch (second switch), SW4 ... Switch (third) Switch), So ... reference signal, T4 ... non-variation period, Vo ... reference voltage, _Vout ... output voltage.

Claims (11)

A wavelength tunable interference filter including two reflective films opposed via the gap between the reflective films, and a gap changing unit that changes the gap between the reflective films to a gap amount corresponding to an applied voltage;
A booster circuit that is driven by a predetermined drive pulse and boosts the reference voltage;
A gap detector for detecting the gap amount;
A voltage output unit that is driven by an output voltage of the booster circuit and outputs the applied voltage according to a detection value of the gap detector;
The optical module, wherein the gap detector detects the gap amount in a non-change period in which the voltage of the drive pulse does not change. The optical module according to claim 1,
The gap detector is
A capacitor for holding a charge corresponding to the gap amount;
A sample and hold circuit for detecting a voltage of the capacitor in which the electric charge is held;
A first switch for switching connection and disconnection of the input end and output end of the capacitor;
A second switch for switching connection and disconnection between the capacitor and the wavelength variable interference filter;
A third switch for switching connection and disconnection between the capacitor and the sample and hold circuit;
The optical module, wherein the third switch is switched during the non-fluctuating period of the drive pulse. The optical module according to claim 2, wherein the gap detector switches the second switch to connect the capacitor and the wavelength tunable interference filter during the non-variation period of the drive pulse. Optical module. The optical module according to claim 2 or 3,
The gap detector includes an input terminal and an output terminal of the first switch after the signal change timing of the drive pulse and before the second switch is switched and the capacitor and the wavelength variable interference filter are connected. And an input end and an output end of the first switch are disconnected. The optical module according to any one of claims 2 to 4,
The gap detector performs switching of the first switch, the second switch, and the third switch during a period from the signal change timing of the drive pulse to the next signal change timing. . The optical module according to any one of claims 1 to 5,
A microcomputer for controlling the voltage output unit;
The optical module, wherein the booster circuit boosts the reference voltage input from the microcomputer. The optical module according to any one of claims 1 to 6,
The optical module, wherein the booster circuit includes a first operational amplifier that amplifies the reference voltage. The optical module according to any one of claims 1 to 7,
A microcomputer for controlling the voltage output unit;
The optical module, wherein the drive pulse is a reference pulse based on a clock frequency of the microcomputer. The optical module according to claim 8, wherein
The booster circuit includes a first operational amplifier that amplifies the reference voltage, and a second operational amplifier that amplifies the voltage value of the reference pulse, and the sum of output values of the first operational amplifier and the second operational amplifier. An optical module characterized in that it outputs a voltage corresponding to it. The optical module according to any one of claims 1 to 9,
The optical module, wherein the booster circuit is a charge pump circuit. A wavelength tunable interference filter including two reflective films opposed via the gap between the reflective films, and a gap changing unit that changes the gap between the reflective films to a gap amount corresponding to an applied voltage;
A booster circuit that is driven by a predetermined drive pulse and boosts the reference voltage;
A gap detector for detecting the gap amount;
A voltage output unit that is driven by the output voltage of the booster circuit and outputs the applied voltage according to the detection value of the gap detector;
A control unit for controlling the voltage output unit,
The electronic device according to claim 1, wherein the gap detector detects the gap amount in a non-change period in which the voltage of the drive pulse does not change.

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