JP5807353B2 - Optical filter, optical filter module, analytical instrument and optical instrument - Google Patents

Description

  The present invention relates to an optical filter, an optical filter module, an analytical instrument, an optical instrument, and the like.

  An interference filter that makes the transmission wavelength variable has been proposed (Patent Document 1). As shown in FIG. 3 of Patent Document 1, a pair of substrates held in parallel with each other, and a pair of multilayer films (reflective films) formed on the pair of substrates so as to face each other and have a gap at a constant interval ) And a pair of electrostatic drive electrodes for controlling the gap. Such a wavelength tunable interference filter can generate an electrostatic attractive force by a voltage applied to the electrostatic drive electrode, control the gap, and change the center wavelength of transmitted light.

Japanese Patent Application Laid-Open No. 11-142752

  However, it is difficult for such a wavelength tunable interference filter to obtain a gap amount with high accuracy due to fluctuations in driving voltage due to noise or the like.

  It is an object of the present invention to provide an optical filter, an optical filter module, an analytical instrument, and an optical instrument that can obtain a gap amount with high accuracy.

(1) An optical filter according to an aspect of the present invention includes:
A first substrate;
A second substrate facing the first substrate;
A first electrode provided on the first substrate;
A first reflective film provided on the first electrode;
A second reflective film provided on the second substrate and facing the first reflective film;
A second electrode provided on the first substrate and formed around the first electrode in a plan view in the thickness direction of the first substrate;
A third electrode provided on the second substrate, formed around the second reflective film in a plan view in the thickness direction of the second substrate, and facing the first electrode;
A fourth electrode provided on the second substrate and facing the second electrode;
It is characterized by including.

  According to one embodiment of the present invention, the semiconductor device includes a third electrode provided on the second substrate and facing the first electrode, and a fourth electrode provided on the second substrate and facing the second electrode. Thereby, as will be described later, it is possible to obtain the gap amount with higher accuracy than in a mode in which the gap amount between the reflective films is controlled only by a pair of electrodes.

(2) In one aspect of the present invention,
The first electrode and the second electrode are electrically independent,
The third electrode and the fourth electrode are electrically connected through a connection portion.

  Since the third electrode and the fourth electrode are electrically connected via the connection portion, the third electrode and the fourth electrode can be used as a common electrode.

(3) In one aspect of the present invention,
A first wiring connected to the first electrode;
A second wiring connected to the second electrode;
Further including
Before Stories second electrode has a first ring shape having a first slit,
Since the second electrode has a second ring shape having the first slit, the first wiring can be drawn from the first electrode through the first slit.

(4) In one aspect of the present invention,
The third electrode has a third ring shape;
The fourth electrode has a fourth ring shape.

  Since the third electrode and the fourth electrode have a ring shape, the parallelism between the reflective films can be kept high when the gap is controlled.

(5) In one aspect of the present invention,
The third electrode has a third ring shape;
The fourth electrode has a fourth ring shape having a second slit,
In plan view, the second slit overlaps the first slit.

  In plan view, the second slit overlaps the first slit. That is, the fourth electrode is not formed above a part of the first wiring formed in the first slit region. Thereby, even if a voltage is applied to the first wiring, it is possible to suppress generation of unnecessary electrostatic attractive force between the first wiring and the fourth electrode.

(6) In one aspect of the present invention,
A third wiring connected to the third electrode;
A fourth wiring connected to the third electrode;
Is further included.

  Since the third wiring and the fourth wiring are connected to the third electrode, the wiring resistance can be reduced.

(7) In one embodiment of the present invention,
The first substrate has a first diagonal line and a second diagonal line,
The first wiring extends in a first direction along the first diagonal,
The second wiring extends along a first diagonal and in a second direction opposite to the first direction;
The third wiring extends in a third direction along the second diagonal;
The fourth wiring extends along a second diagonal line and extends in a fourth direction that is opposite to the third direction.

  Thus, by forming the first wiring, the second wiring, the third wiring, and the fourth wiring, the parasitic capacitance between these wirings can be reduced.

(8) In one embodiment of the present invention,
The ring width of the second electrode is larger than the ring width of the first electrode,
The ring width of the fourth electrode is larger than the ring width of the second electrode.

  Since the second electrode and the fourth electrode are located in a region near the joint portion between the first substrate and the second substrate, an electrostatic attractive force larger than the electrostatic attractive force between the first electrode and the second electrode is required. Therefore, a large electrostatic attraction can be generated by increasing the ring width of the second electrode and the fourth electrode.

(9) In one embodiment of the present invention,
The second substrate has a first part and a second part thinner than the film thickness of the first part,
The second reflective film is formed on the first portion of the second substrate;
The third electrode and the fourth electrode are formed in the second portion of the second substrate.

  Since the third electrode and the fourth electrode are formed in the second portion which is thinner than the film thickness of the first portion, the first substrate can be easily moved when the gap is controlled.

(10) In one embodiment of the present invention,
The first substrate has a first surface and a second surface;
The distance between the first surface and the second substrate is longer than the distance between the second surface and the second substrate,
The first reflective film is formed on the first surface,
The second electrode is formed on the second surface.

(11) In one embodiment of the present invention,
An optical filter, further comprising: a potential difference control unit that controls a potential difference between the first electrode and the third electrode and a potential difference between the second electrode and the fourth electrode.

(12) In one embodiment of the present invention,
The potential difference control unit sets the potential difference between the first electrode and the third electrode to the second potential difference after setting the potential difference between the second electrode and the fourth electrode to the first potential difference. It is characterized by that.

  Thereby, as will be described later, the gap control can be easily performed.

(13) In one embodiment of the present invention,
The potential difference control unit sets the second potential difference in a state where the potential difference control unit is set to the first potential difference.

  Since the second potential difference is set in the state where the first potential difference is set, rapid gap control can be performed as will be described later.

(14) In one embodiment of the present invention,
The potential difference control unit
Setting the potential difference between the second electrode and the fourth electrode to a first potential difference;
After setting the first potential difference, the potential difference between the second electrode and the fourth electrode is set to a second potential difference larger than the first potential difference,
With the second potential difference set, the potential difference between the first electrode and the third electrode is set to a third potential difference,
After setting the third potential difference, the potential difference between the first electrode and the third electrode is set in the state where the potential difference between the second electrode and the fourth electrode is set to the second potential difference. The fourth potential difference is set larger than the third potential difference.

  Thereby, the gap control in more stages can be performed. Moreover, since the second potential difference larger than the first potential difference is set from the first potential difference and the fourth potential difference larger than the third potential difference is set from the third potential difference, quick gap control can be performed.

(15) In one aspect of the present invention,
The period set for the second potential difference is longer than the period set for the first potential difference,
The period set to the fourth potential difference is longer than the period set to the third potential difference.

  Thereby, as will be described later, a desired gap interval can be stabilized.

(16) In one embodiment of the present invention,
The potential difference control unit
Setting the potential difference between the second electrode and the fourth electrode to a first potential difference;
After setting the first potential difference, the potential difference between the second electrode and the fourth electrode is set to a second potential difference larger than the first potential difference,
After setting the second potential difference, the potential difference between the second electrode and the fourth electrode is set to a third potential difference larger than the second potential difference;
With the third potential difference set, the potential difference between the first electrode and the third electrode is set to a fourth potential difference,
After setting the fourth potential difference, the potential difference between the first electrode and the third electrode is set in the state where the potential difference between the second electrode and the fourth electrode is set to the third potential difference. Set the fifth potential difference greater than the fourth potential difference,
After setting the fifth potential difference, the potential difference between the first electrode and the third electrode is set in the state where the potential difference between the second electrode and the fourth electrode is set to the third potential difference. Set the sixth potential difference greater than the fifth potential difference,
The absolute value of the difference between the second potential difference and the third potential difference is smaller than the absolute value of the difference between the first potential difference and the second potential difference;
The absolute value of the difference between the fifth potential difference and the sixth potential difference is smaller than the absolute value of the difference between the fourth potential difference and the fifth potential difference.

  Thereby, as will be described later, a desired gap interval can be stabilized.

(17) An optical filter module according to an aspect of the present invention includes:
And a light receiving element that receives light transmitted through the optical filter.

(18) An analytical instrument according to an aspect of the present invention is provided.
The optical filter described above is included.

(19) An optical device according to an aspect of the present invention includes:
The optical filter described above is included.

It is sectional drawing which shows the voltage non-application state of the optical filter which is one Example of this invention. It is sectional drawing which shows the voltage application state of the optical filter shown in FIG. FIG. 3A is a plan view of the lower electrode, and FIG. 3B is a plan view of the upper electrode. 4A and 4B are plan views of the overlapping state of the lower and upper electrodes as viewed from the second substrate side. It is a top view which shows the wiring layout of the 1st-4th lead-out wiring seeing through the 2nd board | substrate from the 2nd board | substrate side. It is an applied voltage control system block diagram of an optical filter. It is a characteristic view which shows an example of voltage table data. It is a timing chart of the voltage application implement | achieved according to voltage table data. It is a characteristic view which shows the relationship between the gap between the 1st, 2nd reflective films of an optical filter, and a transmission peak wavelength. It is a characteristic view which shows the relationship between the electric potential difference between 1st, 2nd electrodes, and electrostatic attraction. It is a characteristic view which shows the data of the Example regarding the electric potential difference shown in FIG. 7, a gap, and a variable wavelength. It is a characteristic view which shows the relationship between the applied voltage shown in FIG. 11, and a gap. It is a characteristic view which shows the relationship between the applied voltage and transmission peak wavelength which are shown in FIG. 14A and 14B are plan views showing the first and second electrodes of the comparative example. It is a characteristic view which shows the data of the comparative example regarding a potential difference, a gap, and a variable wavelength. It is a characteristic view which shows the relationship between the applied voltage shown in FIG. 15, and a gap. It is a characteristic view which shows the relationship between the applied voltage shown in FIG. 15, and a transmission peak wavelength. It is a block diagram of the analyzer which is further another embodiment of this invention. It is a flowchart which shows the spectroscopic measurement operation | movement with the apparatus shown in FIG. It is a block diagram of the optical equipment which is further another embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described in detail. The present embodiment described below does not unduly limit the contents of the present invention described in the claims, and all the configurations described in the present embodiment are indispensable as means for solving the present invention. Not always.

1. Optical filter 1.1. Filter section of optical filter 1.1.1. FIG. 1 is a cross-sectional view of the optical filter 10 according to the present embodiment in a voltage non-application state, and FIG. 2 is a cross-sectional view of the voltage application state. The optical filter 10 shown in FIGS. 1 and 2 includes a first substrate 20 and a second substrate 30 facing the first substrate 10. In the present embodiment, the first substrate 20 is a fixed substrate and the second substrate 30 is a movable substrate or a diaphragm, but either one or both may be movable.

  In this embodiment, for example, a support portion 22 is formed integrally with the first substrate 20 and movably supports the second substrate 30. The support 22 may be provided on the second substrate 30 or may be formed separately from the first and second substrates 20 and 30.

  The first and second substrates 20 and 30 are made of, for example, various glasses such as soda glass, crystalline glass, quartz glass, lead glass, potassium glass, borosilicate glass, and non-alkali glass, and crystal. . Among these, as a constituent material of each board | substrate 20,30, the glass containing alkali metals, such as sodium (Na) and potassium (K), for example is preferable, and each board | substrate 20,30 is formed with such glass. Thus, it becomes possible to improve the adhesion between the reflective films 40 and 50, which will be described later, and the electrodes 60 and 70, and the bonding strength between the substrates. These two substrates 20 and 30 are integrated by bonding, for example, by surface activated bonding using a plasma polymerization film. Each of the first and second substrates 20 and 30 is formed in a square having a side of, for example, 10 mm, and the maximum diameter of a portion functioning as a diaphragm is, for example, 5 mm.

  The first substrate 20 is formed by processing a glass substrate having a thickness of, for example, 500 μm by etching. In the first substrate 20, for example, a circular first electrode 62 is formed on the first opposing surface 20 </ b> A <b> 1 at the center of the opposing surfaces facing the second substrate 30, and the circular first reflective film 40 is formed thereon, for example. Is formed. Similarly, the second substrate 30 is formed by processing a glass substrate having a thickness of, for example, 200 μm by etching. In the second substrate 30, for example, a circular second reflecting film 50 facing the first reflecting film 40 is formed at the center position of the facing surface 30 </ b> A facing the first substrate 20.

The first and second reflection films 40 and 50 are formed in a circular shape having a diameter of about 3 mm, for example. The first and second reflective films 40 and 50 are reflective films formed of an AgC single layer, and can be formed on the first and second substrates 20 and 30 by a technique such as sputtering. The film thickness dimension of the AgC single-layer reflective film is, for example, 0.03 μm. In the present embodiment, an example in which an AgC single-layer reflective film capable of spectrally diffusing the entire visible light is used as the first and second reflective films 40 and 50 is not limited to this, but the spectral wavelength range is narrow. For example, a laminated film of TiO ₂ and SiO ₂ may be used, which has a higher transmittance of the dispersed light than the AgC single-layer reflective film, a narrow half width of the transmittance, and a good resolution. When the first reflective film 40 is made of a conductive material such as AgC, the entire surface of the first reflective film 40 is in contact with the first electrode 62, so that the charging of the entire first reflective film 40 is reliably removed. be able to. As a result, it is possible to prevent an excessive attractive force or repulsive force from being applied between the first reflective film 40 and the second reflective film 50 due to the charging of the first reflective film 40, and as a result, the first reflective film 40 and the second reflective film can be prevented. The gap between the film 50 can be controlled with high accuracy. Further, when the second reflective film 50 is a conductive material, a wiring (not shown) connected to the second reflective film 50 is drawn out of the optical filter 10 and connected to the same potential as the first electrode (for example, ground potential). As a result, the charge of the entire second reflective film 50 can be reliably removed. Thereby, in addition to the charge removing effect of the first reflective film 40, it is possible to further prevent an excessive attractive force or repulsive force from being applied between the first reflective film 40 and the second reflective film 50. As a result, the first reflective film 40 The gap between the film 40 and the second reflective film 50 can be controlled with higher accuracy.

  Further, an antireflection film (not shown) is provided at a position corresponding to the first and second reflective films 40 and 50 on the surface opposite to the facing surfaces 20A1, 20A2 and 30A of the first and second substrates 20 and 30. AR) can be formed. This antireflection film is formed by alternately laminating a low refractive index film and a high refractive index film, and reduces the reflectance of visible light at the interface between the first and second substrates 20 and 30, thereby reducing the transmittance. Increase.

  The first and second reflective films 40 and 50 are disposed to face each other through the first gap G1 in the voltage non-application state shown in FIG. In the present embodiment, the first reflecting film 40 is a fixed mirror and the second reflecting film 50 is a movable mirror. Either one or both of the two reflective films 40 and 50 can be movable.

  For example, a lower electrode 60 is formed on the second opposing surface 20A2 around the first opposing surface 20A1 of the first substrate 20. Similarly, an upper electrode 70 is provided on the facing surface 30 </ b> A of the second substrate 30 so as to face the lower electrode 60. The lower electrode 60 and the upper electrode 70 are disposed to face each other via the second gap G21 or the third gap G22. The surfaces of the lower and upper electrodes 60 and 70 can be covered with an insulating film.

  In the present embodiment, the surface of the first substrate 20 facing the second substrate 30 is disposed around the first facing surface 20A1 on which the first electrode 62 is formed and the first facing surface 20A1 in plan view. It has 2nd opposing surface 20A2 in which the 2nd electrode 64 of the lower electrodes 60 is formed. The first facing surface is also referred to as the first surface, and the second facing surface is also referred to as the second surface. In the present embodiment, there is a step between the first facing surface 20A1 and the second facing surface 20A2, and the first facing surface 20A1 is set at a position farther from the second substrate 30 than the second facing surface 20A2. Yes. Thereby, the relationship of 1st gap G1 <2nd gap G21, 2nd gap G21> 3rd gap G22 is materialized. The relationship between the sizes of the first gap and the third gap is arbitrary, but it is preferable that the relationship of the first gap G1 ≧ the third gap G22 is established. In FIG. 1 of the present embodiment, the first gap G1 = the third gap G22. Although details will be described later, by setting first gap G1 <second gap G21, second gap G21> third gap G22, the gap between the reflective films can be adjusted efficiently even when a small voltage is applied. .

  The lower electrode 60 is divided into at least K (K is an integer of 2 or more) segment electrodes that are electrically independent, and has first and second electrodes 62 and 64 as an example of K = 2 in this embodiment. That is, the K segment electrodes 62 and 64 can be set to different voltages, respectively, while the upper electrode 70 is a common electrode having the same potential. The upper electrode 70 is also divided into third and fourth electrodes 72 and 74. The third and fourth electrodes 72 and 74 need not be common electrodes having the same potential, and the third electrode 72 and the fourth electrode 74 are electrically independent (can be controlled independently). There may be. For example, the third electrode 72 and the fourth electrode 74 can have a structure as shown in FIG. In addition, the structure of the lower electrode 60 and the upper electrode 70 can independently control the potential difference between the first electrode 62 and the third electrode 72 and the potential difference between the second electrode 64 and the fourth electrode 74. If it is. When K ≧ 3, the relationship described below with respect to the first and second electrodes 62 and 64 can be applied to any two adjacent segment electrodes.

  In the optical filter 10 having such a structure, the first reflective film 40 and the first electrode 62 of the first substrate 20 overlap with each other in plan view in the thickness direction of the first substrate 20. If a transparent electrode such as Indium Tin Oxide is used, sufficient light transmission performance can be obtained.

  Further, in this optical filter 10, a common voltage (for example, ground voltage) is applied to the upper electrode 70 disposed around the second reflective film 50 in plan view, and is disposed around the first reflective film 40 in plan view. Independent voltage is applied to each of the K segment electrodes 62 and 64 constituting the lower electrode 60. Then, by applying an electrostatic attractive force indicated by an arrow between the counter electrodes as shown in FIG. 2, the first gap G1 between the first and second reflective films 40 and 50 is smaller than the size of the initial gap. Variable to be a gap.

  That is, as shown in FIG. 2 showing the optical filter 10 in a voltage application state, the first gap variable drive unit (electrostatic actuator) 80 including the first electrode 62 and the upper electrode 70 facing the first electrode 62, and the second electrode 64. And the 2nd gap variable drive part (electrostatic actuator) 90 comprised with the upper electrode 70 facing it is each independently driven.

  As described above, the K segment electrodes 62 are provided by including the plurality of independent (K) gap variable drive units 80 and 90 arranged only around the first and second reflective films 40 and 50 in plan view. , 64 and the number of segment electrodes selected for applying a voltage from among the K segment electrodes 62, 64 are changed to change the first and second parameters. The size of the gap between the reflective films 40 and 50 is controlled.

  As in Patent Document 1, it is difficult to achieve both a large gap movable range and low sensitivity to voltage fluctuation due to noise or the like when the parameter is only the type of voltage. As in this embodiment, by adding the parameter of the number of electrodes, the same applied voltage range as when controlling by voltage alone is applied to each segment electrode. It is possible to perform fine gap adjustment by generating electrostatic attraction.

  Here, it is assumed that the maximum value of the applied voltage is Vmax and the gap is variable in N stages. When the lower electrode 60 is not divided into a plurality of parts, it is necessary to assign the applied voltage by dividing the maximum voltage Vmax into N parts. At this time, the minimum value of the amount of voltage change between different applied voltages is ΔV1min. On the other hand, in this embodiment, the applied voltage to each of the K segment electrodes may be assigned by dividing the maximum voltage Vmax on average (N / K). At this time, for each of the K segment electrodes, the minimum value of the voltage change amount between different applied voltages applied to the same segment electrode is set to ΔVkmin. In that case, it is clear that ΔV1min <ΔVkmin.

  As described above, if the minimum voltage change amount ΔVkmin can be secured large, the gap fluctuation is small even if the applied voltages to the K first and second electrodes 62 and 64 are somewhat fluctuated due to power supply fluctuations and noise depending on the environment. Become. That is, the sensitivity to noise is small, in other words, the voltage sensitivity is small. As a result, highly accurate gap control is possible, and feedback control of the gap as in Patent Document 1 is not necessarily required. Even if the gap is feedback-controlled, it can be stabilized at an early stage because the sensitivity to noise is small.

  In this embodiment, in order to ensure the flexibility of the second substrate 30 which is a movable substrate, as shown in FIG. 1, the region where the upper electrode 70 is formed is a thin portion 34 having a thickness dimension of about 50 μm, for example. . The thin portion 34 is formed thinner than the thick portion 32 in the region where the second reflective film 50 is disposed and the thick portion 36 in the region in contact with the support portion 22. In other words, in the second substrate 30, the surface 30A on which the second reflective film 50 and the upper electrode 70 are formed is a flat surface, and the thick portion 32 is formed in the first region where the second reflective film 50 is disposed. Then, the thin portion 34 is formed in the second region where the upper electrode 70 is formed. In this way, by making the thick part 32 difficult to bend while securing the flexibility at the thin part 34, the second reflective film 50 can change the gap while maintaining the flatness.

  In the present embodiment, each of the plurality of independent (K) variable gap drive units is constituted by an electrostatic actuator composed of a pair of electrodes, but at least one of them is replaced with another actuator such as a piezoelectric element. May be. However, the electrostatic actuator that applies a suction force in a non-contact manner is suitable for controlling the gap with high accuracy because there is little interference between the plurality of gap variable drive units. On the other hand, for example, when two piezoelectric elements are arranged between the first and second substrates 20 and 30, the piezoelectric elements that are not driven are present to prevent gap displacement caused by other driven piezoelectric elements. For example, a plurality of variable gap drive units are driven independently. From this point, it is preferable that the plurality of gap variable drive units be configured by electrostatic actuators.

1.1.2. Lower electrode The K segment electrodes 62 and 64 constituting the lower electrode 60 can be arranged concentrically with respect to the center of the first reflective film 40 as shown in FIG. That is, the first electrode 62 has a first circular electrode portion 62A, and the second electrode 64 has a second ring-shaped electrode portion 64A outside the first circular electrode portion 62A. The first circular electrode portion 62 </ b> A and the second ring electrode portion 64 </ b> A are formed concentrically with respect to the first reflective film 40 in a plan view of the first substrate 20. “Circular” or “circular” is a term that includes not only a circle but also a polygon. The term “ring shape” or “ring shape” is a term including not only an endless ring but also a discontinuous ring shape, and not only a circular ring but also a rectangular ring or a polygonal ring.

  As a result, as shown in FIG. 2, the first and second electrodes 62 and 64 are arranged symmetrically with respect to the center line L of the first reflective film 40. Accordingly, the electrostatic attractive forces F1 and F2 acting between the lower and upper electrodes 60 and 70 when a voltage is applied act symmetrically with respect to the center line L of the first reflective film 40, and thus the first and second reflections. The parallelism of the films 40 and 50 is increased.

  As shown in FIG. 3A, the ring width W2 of the second electrode 64 can be made larger than the ring width W1 of the portion of the first electrode 62 facing the third electrode 72 (W2> W1). ). In FIG. 3A, the inner diameter portion of the ring-shaped third electrode is indicated by a dotted line. This is because the electrostatic attractive force is proportional to the electrode area, and the electrostatic attractive force F2 generated by the second electrode 64 is required to be larger than the electrostatic attractive force F1 generated by the first electrode 62. More specifically, the outer second electrode 64 is provided closer to the substrate support part 22 that functions as a hinge part than the first electrode 62. For this reason, it is preferable that the 2nd electrode 64 can generate | occur | produce the big electrostatic attraction F2 which resists the resistance force in the board | substrate support part 22 (hinge part). The outer second electrode 64 has a larger diameter than the inner first electrode 62, and the area of the second electrode 64 is large even when the width W1 = the width W2. Therefore, the width W1 may be equal to the width W2, but by increasing the ring width W2, the area can be further increased to generate a large electrostatic attractive force F2. When the outer second electrode 64 is driven before the inner first electrode 62, the third gap G22 corresponding to the second electrode 64 is between the second electrode 64 and the fourth electrode 74. It is narrowed by the electrostatic attraction that acts. At this time, the second gap G21 is also narrowed and becomes smaller than the initial gap. Therefore, when driving the first electrode 62, the second gap G21 is smaller than the initial value. Here, it is assumed that the first surface 20A1 and the second surface 20A2 are flush with each other, and the initial values of the second gap G21 and the third gap G22 are the same. In this case, for example, the third gap G22 when the second electrode 64 is first driven becomes larger than the second gap G21 when the first electrode 62 is driven later. Therefore, it is necessary to set the electrostatic attractive force when the second electrode 64 is first driven to be excessively larger than the electrostatic attractive force when the first electrode 64 is driven. Therefore, in this case, as shown in FIG. 1, the initial value of the third gap G22 is preferably made smaller than the initial value of the second gap G21. Furthermore, although the larger initial value of the third gap G22 than the initial value of the first gap G1 is suitable for increasing the moving distance of the second reflective film 50, the static necessary for the above-described driving is preferred. There is a problem of the magnitude of the electric attractive force. Therefore, in the present embodiment, considering these balances, the initial value of the first gap G1 is set to the initial value of the third gap G22. Alternatively, the initial value of the first gap G1 may be greater than the initial value of the third gap G22. In this case, the second electrode 64 and the fourth electrode 74 can be driven with a small electrostatic attraction on the one hand, and the first gap G1 <the second gap G21 on the other hand. By driving the electrode 72, the moving distance of the second reflective film 50 can be increased, and as a result, the reflective film can be sufficiently moved with a small electrostatic attraction.

  Here, the first extraction wiring 62B is connected to the first electrode 62, and the second extraction wiring 64B is connected to the second electrode 64, respectively. The first and second lead wirings 62B and 64B are formed to extend in the radial direction from the center of the first reflective film 40, for example. A first slit 64C that makes the second ring-shaped electrode portion 64A of the second electrode 64 discontinuous is provided. The first lead wiring 62 </ b> B extending from the inner first electrode 62 is led out of the second electrode 64 through the first slit 64 </ b> C formed in the outer second electrode 64.

  As described above, when the first and second electrodes 62 and 64 are the first circular electrode portion 62A and the ring-shaped electrode portion 64A, respectively, the inner side of the first slit 64C2 formed in the outer second electrode 64. Thus, it is possible to easily secure a lead-out path for the first lead wiring 62B of the first electrode 62.

1.1.3. Upper electrode The upper electrode 70 disposed on the second substrate 30 includes a region of the second substrate 30 that faces the lower electrode 60 (first and second electrodes 62 and 64) formed on the first substrate 20. Can be formed in the area. When the upper electrode 70 is a common electrode set to the same voltage, for example, a solid electrode may be used.

  Instead, the upper electrode 70 disposed on the second substrate 30 that is displaced with respect to the first substrate 20 as in the present embodiment can be K segment electrodes, similarly to the lower electrode 60. . The K segment electrodes can also be arranged concentrically with respect to the center of the second reflective film 50. In this way, the area of the electrode formed on the movable second substrate 30 is reduced to the minimum necessary, so that the rigidity of the second substrate 30 is reduced and the ease of bending can be ensured.

  The K segment electrodes constituting the upper electrode 70 can include a third electrode 72 and a fourth electrode 74 as shown in FIGS. 1, 2, and 3B. The third electrode 72 has a third ring-shaped electrode portion 72A, and the fourth electrode 74 has a fourth ring-shaped electrode portion 74A outside the third ring-shaped electrode portion 72A, and each ring-shaped electrode portion 72A, 74A. Are formed in a concentric ring shape with respect to the second reflective film. The meaning of “concentric ring shape” is the same as that for the lower electrode 60. The third electrode 72 faces a part of the first electrode 62, and the fourth electrode 74 faces the second electrode 64. Therefore, in the present embodiment, the ring width of the fourth electrode 74 (same as the ring width W2 of the second electrode 64) is wider than the ring width of the third electrode 72.

  Further, the third and fourth electrodes 72 and 74 may be electrically connected and set to the same potential. In this case, for example, the third and fourth lead wires 76A and 76B are formed to extend in the radial direction from the center of the second reflective film 50, for example. Each of the third and fourth lead wires 76A and 76B is electrically connected to both the inner third electrode 72 and the outer fourth electrode 74. Since the third and fourth electrodes 72 and 74 are common electrodes, they may be connected by a single lead-out wiring. However, by using a plurality of lead-out wirings, the wiring resistance is reduced, and the common electrode Charge / discharge speed can be increased. In the case where the third and fourth electrodes 72 and 74 are electrically independent, lead wires are formed on the respective electrodes.

1.1.4. FIG. 4A shows an overlapping state in plan view of the lower and upper electrodes 60 and 70 of the present embodiment when viewed from the second substrate 30 side. 4A, in the lower electrode 60 located on the lower side, the first and second electrodes 62 and 64 are opposed to the third and fourth electrodes 72 and 74 of the upper electrode 70, respectively. Therefore, the lower electrode 60 located on the lower side faces the first and second lead wires 62B and 64B, the third electrode of the first electrode 62, and the second reflective film 50 as shown by hatching. Only the non-existent portion appears in a plan view as viewed from the second substrate 30 side. In the first lead-out wiring 62B, since the fourth ring-shaped electrode portion 74A of the upper electrode 70 is continuous in the circumferential direction, the intermediate region 62B1 faces the facing region 74A1 of the fourth ring-shaped electrode portion 74A.

  In the present embodiment, as shown in FIG. 3A, the outer second electrode 64 of the lower electrode 60 has a first slit 64C, so that the second electrode 64 is applied in the area of the slit 64C. The electrostatic attractive force F2 (see FIG. 2) based on the voltage does not act.

  On the other hand, as shown in FIG. 3A, the first lead-out wiring 62B is arranged in the first slit 64C, so that the first lead-out wiring 62B having the same potential as the inner first electrode 62 and the outer lead-out wiring 62B are arranged. An electrostatic attractive force F1 (see FIG. 2) acting between the fourth electrodes 74 can be generated in the first slit 64C. As an advantage, for example, when the first and second electrodes 62 and 64 are driven at substantially the same voltage, almost the entire circumference of the outer fourth electrode 74 (including the region 74A1 facing the first slit 64C). It is possible to generate a uniform electrostatic attraction force.

  FIG. 4B shows a state in which the lower and upper electrodes 60 and 70 ′ as a modification are overlapped in a plan view when viewed from the second substrate 30 side. 4B is different from the upper electrode 70 of FIG. 4A in that the fourth electrode 74 is in a fourth ring shape at a position facing the first slit 64C of the lower electrode 60. This is a point further having a second slit 78 that makes the electrode portion 74A ′ discontinuous. In other respects, the upper electrode 70 ′ in FIG. 4B is the same as the upper electrode 70 in FIG.

  As a result, there is no electrode facing the first lead wiring 62B. Therefore, for example, when the inner first electrode 62 is driven, an unnecessary electrostatic attractive force acting between the first lead wiring 62B having the same potential as the inner first electrode 62 and the outer fourth electrode 74 ′ is generated. , It can be prevented from occurring in the first slit 64C.

1.1.5. Drawing Wiring FIG. 5 is a plan view of the second substrate 30 seen through from the second substrate 30 side, and shows the wiring layout of the first to fourth drawing wirings 62B, 64B, 76A, and 76B. In FIG. 5, at least one of the first and second substrates 20 and 30 is a rectangular substrate having first and second diagonal lines. In the present embodiment, each of the first and second substrates 20 and 30 is formed in a square having a side of, for example, 10 mm. When the direction in which the first lead wiring 62B extends from the first circular electrode portion 62A along the first diagonal is the first direction D1, the second lead wiring 64B is connected to the first direction D1 on the first diagonal. Extends in the second direction D2, which is the opposite direction. The third lead wiring 76A extends in the third direction D3 along the second diagonal. The fourth lead wiring 76B extends in the fourth direction D4 which is opposite to the third direction D3 on the second diagonal line. And the 1st-4th connection electrode part 101-104 to which the 1st-4th lead-out wiring 62B, 64B, 76A, 76B is connected is provided in the position of the four corners of the rectangular substrates 20 and 30 by planar view. ing.

  In this way, first, the first and second lead wires 62B and 64B formed on the first substrate 20 and the third and fourth lead wires 76A and 76B formed on the second substrate 30 overlap in plan view. It does not constitute a parallel electrode. Therefore, useless electrostatic attraction is hardly generated between the first and second lead wirings 62B and 64B and the third and fourth lead wirings 76A and 76B, and useless capacity can be reduced. Furthermore, the wiring lengths of the first to fourth lead wirings 62B, 64B, 76A and 76B reaching the first to fourth connection electrode portions 101 to 104, respectively, are the shortest. Therefore, the wiring resistance and wiring capacity of the first to fourth lead wirings 62B, 64B, 76A, and 76B are reduced, and the first to fourth electrodes 62, 64, 72, and 74 can be charged and discharged at high speed.

  The first to fourth lead wirings 62B, 64B, 76A, and 76B have a structure in which the first substrate has a first virtual line and a second virtual line that intersects the first virtual line in plan view. The first lead wiring 62B extends in the first direction along the first virtual straight line, and the second lead wiring 64B extends in the second direction along the first virtual straight line and opposite to the first direction. The third lead wiring 76A extends in the third direction along the second virtual straight line, and the fourth lead wiring 76B extends along the second virtual straight line and in the opposite direction to the third direction. It may be extended in the fourth direction.

  The first to fourth external connection electrode portions 101 to 104 may be partially provided on either one or both of the first and second substrates 20 and 30. In the case where the first to fourth external connection electrode portions 101 to 104 are provided only on one of the first and second substrates 20 and 30, the lead wiring disposed on the other of the first and second substrates 20 and 30. Can be connected to an external connection electrode portion formed on one substrate by a conductive paste or the like. The first to fourth external connection electrode portions 101 to 104 are connected to the outside through connection portions such as lead wires or wire bonding.

  Further, the first to fourth lead wirings 62B, 64B, 76A, and 76B may intersect with, for example, a plasma polymerization film that joins the first and second substrates 20 and 30. Alternatively, even if the first to fourth lead wirings 62B, 64B, 76A, and 76B are pulled out beyond the joint surface through a groove provided on one of the joint surfaces of the first and second substrates 20 and 30, good.

1.2. Voltage control system of optical filter 1.2.1. Overview of Applied Voltage Control System Block FIG. 6 is an applied voltage control system block diagram of the optical filter 10. As shown in FIG. 6, the optical filter 10 includes a potential difference control unit 110 that controls a potential difference between the lower electrode 60 and the upper electrode 70. In the present embodiment, since the upper electrode 70 (third and fourth electrodes 72 and 74), which is a common electrode, is fixed to a constant common voltage, for example, the ground voltage (0 V), the potential difference control unit 110 includes the lower electrode 60. An inner peripheral side between each of the first and second electrodes 62 and 64 and the upper electrode 70 by changing the applied voltage to the first and second electrodes 62 and 64 which are K segment electrodes constituting The potential difference ΔVseg1 and the outer peripheral side potential difference ΔVseg2 are controlled. The upper electrode 70 may apply a common voltage other than the ground voltage. In this case, the potential difference control unit 110 may control application / non-application of the common voltage to the upper electrode 70.

  In FIG. 6, the potential difference controller 110 includes a first electrode driver connected to the first electrode 62, such as a first digital-analog converter (DAC1) 112, and a second electrode driver connected to the second electrode 64, such as A second digital-analog converter (DAC2) 114 and a digital control unit 116 that controls them, for example, digitally control them, are included. The voltage from the power source 120 is supplied to the first and second digital-analog converters 112 and 114. The first and second digital-analog converters 112 and 114 receive the supply of voltage from the power source 120 and output an analog voltage corresponding to the digital value from the digital control unit 116. As the power source 120, an analysis device to which the optical filter 10 is attached or a device equipped in the optical device can be used, but a power source dedicated to the optical filter 10 may be used.

1.2.2. Optical Filter Driving Method FIG. 7 is a characteristic diagram illustrating an example of voltage table data which is original data for control in the digital control unit 116 illustrated in FIG. 6. This voltage table data may be provided in the digital control unit 116 itself, or may be provided in an analytical instrument or an optical instrument to which the optical filter 10 is attached.

  FIG. 7 is a diagram for varying the gap between the first and second reflective films 40 and 50 in a total of N stages by sequentially applying a voltage to each of the K first and second electrodes 62 and 64. An example of N = 9 is shown as voltage table data. In FIG. 7, when both potential differences between both the first and second electrodes 62 and 64 and the upper electrode 70 are 0V, they are not included in the N-stage gap variable range. FIG. 7 shows only a case where a voltage value other than the voltage value (0 V) of the common voltage applied to the upper electrode 70 is applied to at least one of the first and second electrodes 62 and 64. However, the transmission peak wavelength may be defined as the maximum when each potential difference between both the first and second electrodes 62 and 64 and the upper electrode 70 is 0V.

  In accordance with the voltage table data shown in FIG. 7, the potential difference control unit 110 converts the voltage value set for each of the K segment electrodes (first and second electrodes 62 and 64) into the K segment electrodes (first and first electrodes). The two electrodes 62 and 64) are applied. FIG. 8 is a timing chart of voltage application realized by driving in the order of the data numbers of the voltage table data shown in FIG.

  As shown in FIGS. 7 and 8, L = 4 kinds of voltages (VI1 to VI4: VI1 <VI2 <VI3 <VI4) are applied to the first electrode 62, and M = 5 is applied to the second electrode 64. Various voltages (VO1 to VO5: VO1 <VO2 <VO3 <VO4 <VO5) are applied, and the first gap G1 between the first and second reflective films 40 and 50 is set to 9 (g = g + g = 9) (N = L + M = 9) Variable at stage.

  By such voltage control, the optical filter 10 can realize the wavelength transmission characteristics shown in FIG. FIG. 9 shows wavelength transmission characteristics when the size of the first gap G1 between the first and second reflective films 40 and 50 is changed to, for example, g0 to g3. In the optical filter 10, when the size of the first gap G1 between the first and second reflective films 40 and 50 is varied, for example, from g0 to g3 (g0> g1> g2> g3), the first gap G1. The transmission peak wavelength is determined in accordance with the size of. That is, the wavelength λ of the light transmitted through the optical filter 10 is light whose integer (n) times the half wavelength (λ / 2) coincides with the first gap G1 (n × λ = 2G1), and the half wavelength ( Light whose integer (n) times (λ / 2) does not coincide with the first gap G1 interferes with each other in the process of multiple reflection by the first and second reflection films 40 and 50, and does not pass through. .

  Therefore, as shown in FIG. 9, the size of the first gap G1 between the first and second reflective films 40 and 50 is changed to be narrowed to g0, g1, g2, and g3, so that the light filter 10 is transmitted. The light to be transmitted, that is, the transmission peak wavelength, changes to λ0, λ1, λ2, and λ3 (λ0> λ1> λ2> λ3) in order to become shorter.

  Here, the values of L, M, and N can be arbitrarily changed, but are preferably integers of L ≧ 3, M ≧ 3, and N ≧ 6. When L ≧ 3, M ≧ 3, and N ≧ 6, the second potential difference ΔV2 and the second potential difference that are set for the first and second electrodes 62 and 64 are larger than the first potential difference ΔV1 from the first potential difference ΔV1. The inner peripheral potential difference ΔVseg1 and the outer peripheral potential difference ΔVseg2 can be switched to a third potential difference ΔV3 that is larger than ΔV2.

  As illustrated in FIG. 7, the potential difference control unit 110 first sequentially applies the voltages VO1 to VO5 to the outer second electrode 64. Since the upper electrode 70 is 0 V, the potential difference between the upper electrode 70 and the second electrode 64 is the first potential difference VO1, the second potential difference VO2, the third potential difference VO3, the fourth potential difference VO4, and the fifth potential difference VO5. The outer peripheral potential difference Vseg2 can be increased sequentially. As a result, the size of the first gap G1 between the first and second reflective films 40 and 50 becomes narrower in the order of go → g1 → g2 → g3 → g4. As a result, the light transmitted through the optical filter 10, that is, the transmission peak wavelength, changes so as to become shorter in order of λ 0 → λ 1 → λ 2 → λ 3 → λ 4.

  Next, as shown in FIG. 7, the potential difference control unit 110 maintains the application of the maximum applied voltage VO5 to the second electrode 64, and the potential difference control unit 110 applies the voltage VI1 to the voltage VI4 to the inner first electrode 62. Are sequentially applied. Since the upper electrode 70 is 0V, the potential difference between the upper electrode 70 and the first electrode 62 is the first potential difference VI1, the second potential difference VI2, the third potential difference VI3, the fourth potential difference VIO4, and the inner peripheral potential difference. Vseg1 can be increased sequentially. As a result, the size of the first gap G1 between the first and second reflective films 40 and 50 decreases in order of g5 → g6 → g7 → g8. As a result, the light transmitted through the optical filter 10, that is, the transmission peak wavelength, changes so as to be sequentially shortened from λ5 → λ6 → λ7 → λ8.

  The potential difference control unit 110 switches at least the first potential difference VO1 from the first potential difference VO1 to the second potential difference VO2 that is greater than the first potential difference VO1, and further to the third potential difference VO3 that is greater than the second potential difference VO2. The potential difference control unit 110 switches at least the first potential difference VI1 to the second potential difference VI2 that is larger than the first potential difference VI1 and the third potential difference VI3 that is larger than the second potential difference VI2 with respect to the inner peripheral potential difference Vseg1. Thereby, it is possible to suppress the damped free vibration of the second substrate 30 on the movable side, and it is possible to perform a quick wavelength variable operation. Moreover, the potential difference control unit 110 uses at least the first segment voltage VI1 with respect to the first electrode 62 as a voltage of three or more values (which may include voltage 0) for each of the first and second electrodes 62 and 64. The second segment voltage VI2 and the third segment voltage VI3 are applied to the second electrode 64 with at least the first segment voltage VO1, the second segment voltage VO2, and the third segment voltage VO3. Therefore, by driving only one of the first and second electrodes 62 and 64, the gap can be varied in three or more stages, and the number of segment electrodes of the lower electrode 60 does not need to be increased unnecessarily.

1.2.3. Voltage change amount (absolute value of difference between first potential difference and second potential difference, etc.)
The potential difference control unit 110 sets the absolute value of the difference between the second potential difference and the third potential difference for each of the inner peripheral potential difference Vseg1 and the outer peripheral potential difference Vseg2 to be larger than the absolute value of the difference between the first potential difference and the second potential difference. Can be small. In the present embodiment, since the upper electrode 70 does not change at a common voltage of 0 V, for example, the absolute value of the difference between the first potential difference and the second potential difference as the outer peripheral side potential difference Vseg2 is as shown in FIGS. This is equivalent to the voltage change amount ΔVO1 between the first segment voltage VO1 and the second segment voltage VO2 applied to the second electrode 64. As shown in FIG. 7 and FIG. 8, the voltage change amount of the outer peripheral side potential difference Vseg2 has a relationship of ΔVO1>ΔVO2>ΔVO3> ΔVO4, which gradually decreases. It is in a relationship that gradually decreases.

  The reason for this relationship is as follows.

The electrostatic attractive force F can be expressed as “F = (1/2) ε (V / G) ² S”. Here, ε: dielectric constant, V: applied voltage, G: gap between electrodes, and S: electrode facing area. From this equation, the electrostatic attractive force F is proportional to the square of the potential difference between the lower and upper electrodes 60 and 70 (in this embodiment, the applied voltage V to the lower electrode 60). FIG. 10 is a characteristic diagram of the electrostatic attractive force F proportional to the square of the potential difference V (f = V ² ). As shown in FIG. 10, when switching between the first potential difference, the second potential difference, and the third potential difference in the direction in which the potential difference V increases, the absolute value ΔV1 of the difference between the first potential difference and the second potential difference and the second potential difference And the third potential difference have the same absolute value difference ΔV2 (ΔV1 = ΔV2 in FIG. 10), the amount of increase in electrostatic attraction ΔF increases rapidly from ΔF1 to ΔF2, causing overshoot. Become.

  Therefore, the absolute value ΔV2 of the difference between the second potential difference and the third potential difference is made smaller than the absolute value ΔV1 of the difference between the first potential difference and the second potential difference. As a result, a sudden increase in electrostatic attraction when the gap is narrowed can be suppressed, overshoot can be further suppressed, and more rapid wavelength variable operation can be realized.

1.2.4. Voltage Application Period The potential difference control unit 110 sets the second potential difference for each of the inner periphery side potential difference Vreg1 and the outer periphery side potential difference Vreg2 to be longer than the period set for the first potential difference, and sets the third potential difference. The set period can be longer than the period set for the second potential difference. In the present embodiment, as shown in FIG. 8, regarding the outer peripheral side potential difference Vreg2, the period TO2 of the second potential difference VO2 is longer than the period TO1 of the first potential difference VO1, and the period TO3 of the third potential difference VO3 is the second potential difference. It is longer than the period TO2 of VO2, and has a relationship of TO1 <TO2 <TO3 <TO4 <TO5, which is sequentially longer. Similarly, as shown in FIG. 8, regarding the inner peripheral side potential difference Vreg1, the period TI2 of the second potential difference VI2 is longer than the period TI1 of the first potential difference VI1, and the period TI3 of the third potential difference VI3 is the second potential difference VI2. The period TI2 is longer than the period TI2, and is sequentially increased as TI1 <TI2 <TI3 <TI4.

  When the second potential difference is larger than the first potential difference, or when the third potential difference is larger than the second potential difference, the restoring force of the second substrate 30 is also increased. For this reason, the time until the second substrate 30 comes to rest becomes longer. That is, the time until the first gap G1 between the first and second reflective films 40 and 50 is stabilized at a fixed position becomes longer. On the other hand, as in this embodiment, the period set to the second potential difference is longer than the period set to the first potential difference, and the period set to the third potential difference is set to the second potential difference. By setting longer than the set period, the first gap G1 can be stabilized at a predetermined value.

1.2.5. Example of Potential Difference, Gap and Variable Wavelength FIG. 11 is a characteristic diagram showing data of the example of the potential difference, gap and variable wavelength shown in FIG. Data numbers 1 to 9 in FIG. 11 are the same as data numbers 1 to 9 in FIG. FIG. 12 is a characteristic diagram showing the relationship between the applied voltage and the gap shown in FIG. FIG. 13 is a characteristic diagram showing the relationship between the applied voltage and the transmission peak wavelength shown in FIG.

  In FIG. 11, the first gap G1 between the first and second reflective films 40 and 50 is the maximum in order to vary the transmission peak wavelength in nine steps from the maximum wavelength λ0 = 700 nm to the minimum wavelength λ8 = 380 nm. The gap is changed in nine steps from the gap g0 = 300 nm to the minimum gap g8 = 140 nm (see also FIG. 12). Correspondingly, the transmission peak wavelength is varied in nine steps from the maximum wavelength λ0 to the minimum wavelength λ8 (see also FIG. 13). Furthermore, in FIG. 11, nine stages of wavelengths λ0 to λ8 from the maximum wavelength λ0 to the minimum wavelength λ8 are set by setting the nine stages of gabs g0 to g8 from the maximum gap g0 to the minimum gap g8 at equal intervals (= 40 nm). λ8 is also equally spaced (= 40 nm). In this way, by changing the size of the first gap G1 between the first and second reflective films so that the first gap G1 gradually decreases by a certain amount, the transmission peak wavelength also decreases by a certain value.

  The potential difference control unit 110 sequentially sets the outer side potential difference Vseg2 to VO1 = 16.9V, VO2 = 21.4V, VO3 = 25V, VO4 = 27.6V, VO5 = 29.8V, and maintains VO5 = 29.8V. The inner peripheral potential difference Vseg1 is sequentially set to VI1 = 16.4V, VI2 = 22.2V, VI3 = 26.3V, and VI4 = 29.3V.

  The size of the first gap G1 between the first and second reflective films 40 and 50 is more influenced by the electrostatic attractive force F1 based on the inner peripheral potential difference Vreg1 than the electrostatic attractive force F2 based on the outer peripheral potential difference Vreg2. Is big. Therefore, even if the inner peripheral side potential difference Vreg1 is first changed and then the outer peripheral side potential difference Vreg2 is changed while the inner peripheral side potential difference Vreg1 is maintained at a constant value, the electrostatic attractive force F1 due to the inner peripheral side potential difference Vreg1 is dominant. Thus, the gap between the first and second reflective films 40 and 50 does not change as the outer peripheral potential difference Vreg2. Therefore, in the present embodiment, first, the outer peripheral potential difference Vreg2 is changed, and then the inner peripheral potential difference Vreg1 is changed while the outer peripheral potential difference Vreg2 is maintained at a constant value.

  The potential difference control unit 110 maintains the outer peripheral side potential difference Vreg2 at the outer peripheral side maximum potential difference VO5 and changes the inner peripheral side potential difference Vreg1 after the outer peripheral side potential difference Vreg2 reaches the outer peripheral side maximum potential difference VO5. In this way, it is possible to further change the gap for one step by applying the inner peripheral side potential difference Vreg1 from the first gap G1 set by the outer peripheral side maximum potential difference VO5. Moreover, after the inner peripheral potential difference Vreg1 is applied, the outer peripheral side maximum outer peripheral potential difference VO5 has already been reached, so there is no need to further change the outer peripheral potential difference Vreg2. Therefore, when the outer peripheral side potential difference Vreg2 is changed, the dominant electrostatic attractive force F2 due to the inner peripheral side potential difference Vreg1 does not occur.

  When the potential difference control unit 110 sets the inner circumference side potential difference Vreg1 to the inner circumference side maximum potential difference VI4, the first gap G1 between the first and second reflection films 40 and 50 is set to the minimum gap g8. Each of the outer circumference side maximum potential difference VO5 and the inner circumference side maximum potential difference VI4 can be made substantially equal within a range not exceeding the maximum voltage Vmax supplied to the potential difference control unit 110. In the present embodiment, for example, the maximum voltage Vmax = 30 V is supplied from the power source 120 shown in FIG. At this time, the outer peripheral side maximum potential difference VO5 is set to 29.8V not exceeding the maximum voltage Vmax (30V), and the inner periphery side maximum potential difference VI4 is also set to 29.3V not exceeding the maximum voltage Vmax (30V). ing.

  In FIG. 11, there is a slight difference of 0.5 V between the inner peripheral maximum potential difference VO5 and the inner peripheral maximum potential difference VI4, but it can be said that they are substantially the same. This minute difference is that the transmission peak wavelengths at equal intervals are obtained at full scale (see FIGS. 12 and 13) in a range not exceeding the maximum voltage Vmax (30 V) for each of the inner peripheral potential difference Vreg1 and the outer peripheral potential difference Vreg2. This is the result of the design. In order to make the inner circumference side maximum potential difference VO5 and the inner circumference side maximum potential difference VI4 exactly match, it is possible to adjust the area ratio of the first and second electrodes 62 and 64, but it is necessary to make them exactly match. Is scarce. In the driving method according to the present embodiment, the inner circumference maximum potential difference VO5 and the inner circumference maximum potential difference VI4 are made substantially equal to each other, as described with reference to FIG. There is an advantage that an equal electrostatic attraction can be generated almost all around (including the region 74A1 facing the first slit 64C).

  In the present embodiment, the potential difference control unit 110 sequentially applies a voltage to each of the K = 2 first and second electrodes 62 and 64, so that the first and second reflective films 40 in a total of N = 9 stages. , 50 can be changed. At this time, the minimum value of the voltage change amount between the applied voltages applied to the same segment electrode 62 (or 64) of K = 2 first and second electrodes 62 and 64 is defined as ΔVkmin. In the example of FIGS. 7 and 11, ΔVkmin = ΔVI3 = 3.0V for the first electrode 62 and ΔVkmin = ΔVO4 = 2.2V for the second electrode 64. Considering that the power supply noise is about 0.1 V, it is clear from the comparison with the following comparative example that this minimum voltage value ΔVkmin is less sensitive to noise.

1.2.6. Comparative Example In a comparative example, as shown in FIGS. 14A and 14B, the lower electrode 61 shown in FIG. 14A is replaced with the upper electrode 70 of this embodiment instead of the lower electrode 60 of this embodiment. The upper electrode 71 shown in FIG. That is, the lower and upper electrodes 61 and 71 of the comparative example are not segmented.

  FIG. 15 is a characteristic diagram showing the potential difference between the lower and upper electrodes 61 and 71 shown in FIGS. 14A and 14B, and the gap and variable wavelength data obtained thereby. Data numbers 1 to 9 in FIG. 15 are the same as data numbers 1 to 9 in FIGS. FIG. 16 is a characteristic diagram showing the relationship between the applied voltage and the gap shown in FIG. FIG. 17 is a characteristic diagram showing the relationship between the applied voltage and the transmission peak wavelength shown in FIG.

  Also in FIG. 15, the first gap G1 between the first and second reflection films 40 and 50 is the maximum in order to vary the transmission peak wavelength in nine steps from the maximum wavelength λ0 = 700 nm to the minimum wavelength λ8 = 380 nm. The gap is changed in nine steps from the gap g0 = 300 nm to the minimum gap g8 = 140 nm (see also FIG. 15). Correspondingly, the transmission peak wavelength is varied in nine steps from the maximum wavelength λ0 to the minimum wavelength λ8 (see also FIG. 16).

  However, in the comparative example, the nine levels of voltage applied to the lower electrode 61, which is a single electrode, must be set within the full scale of the maximum voltage Vmax (30v).

  As in the comparative example, the minimum voltage change amount between the applied voltages at N = 9 stages when the lower electrode 61 is formed of a single electrode is defined as ΔV1min. In the example of FIG. 15, ΔV1min = 0.9V. Considering that the power supply noise is about 0.1V, the voltage minimum change amount ΔV1min of the comparative example is highly sensitive to noise.

  When the voltage minimum change amount ΔVkmin of the present embodiment is compared with the voltage minimum change amount V1min of the comparative example, ΔV1min <ΔVkmin is established, and in this embodiment, sensitivity to noise can be reduced.

2. Analysis Instrument FIG. 18 is a block diagram showing a schematic configuration of a colorimeter that is an example of an analysis instrument according to an embodiment of the present invention.

  In FIG. 18, the colorimeter 200 includes a light source device 202, a spectroscopic measurement device 203, and a colorimetry control device 204. The colorimeter 200 emits, for example, white light from the light source device 202 toward the inspection target A, and causes the inspection target light, which is light reflected by the inspection target A, to enter the spectroscopic measurement device 203. Then, spectral characteristic measurement is performed in which the spectroscopic measurement device 203 divides the inspection target light and measures the amount of the split light of each wavelength. In other words, the inspection target light, which is the light reflected by the inspection target A, is incident on the optical filter (etalon) 10 and the spectral characteristic measurement is performed to measure the amount of transmitted light transmitted from the etalon 10. Then, the colorimetric control device 204 analyzes the colorimetric processing of the inspection object A, that is, how much color of which wavelength is included, based on the obtained spectral characteristics.

  The light source device 202 includes a light source 210 and a plurality of lenses 212 (only one is shown in FIG. 1), and emits white light to the inspection target A. The plurality of lenses 212 includes a collimator lens. The light source device 202 converts white light emitted from the light source 210 into parallel light by the collimator lens, and travels from the projection lens (not shown) toward the inspection object A. And inject.

  As shown in FIG. 18, the spectroscopic measurement device 203 includes the etalon 10, a light receiving unit 220 including a light receiving element, a drive circuit 230, and a control circuit unit 240. Further, the spectroscopic measurement device 203 includes an incident optical lens (not shown) that guides the reflected light (measurement target light) reflected by the inspection target A to a position facing the etalon 10.

  The light receiving unit 220 includes a plurality of photoelectric exchange elements (light receiving elements), and generates an electrical signal corresponding to the amount of received light. The light receiving unit 220 is connected to the control circuit unit 240 and outputs the generated electric signal to the control circuit unit 240 as a light reception signal. The etalon 10 and the light receiving unit (light receiving element) 220 are unitized to form an optical filter module.

  The drive circuit 230 is connected to the lower electrode 60, the upper electrode 70, and the control circuit unit 240 of the etalon 10. The drive circuit 230 applies a drive voltage between the lower electrode 60 and the upper electrode 70 based on the drive control signal input from the control circuit unit 240, and moves the second substrate 30 to a predetermined displacement position. The driving voltage may be applied so that a desired potential difference is generated between the lower electrode 60 and the upper electrode 70. For example, a predetermined voltage is applied to the lower electrode 60 and the upper electrode 70 is set to the ground potential. Good. A DC voltage is preferably used as the drive voltage.

  The control circuit unit 240 controls the overall operation of the spectroscopic measurement apparatus 203. As shown in FIG. 18, the control circuit unit 240 includes, for example, a CPU 250, a storage unit 260, and the like. Then, the CPU 250 performs spectroscopic measurement processing based on various programs and various data stored in the storage unit 260. The storage unit 260 is configured to include a recording medium such as a memory or a hard disk, and stores various programs, various data, and the like so as to be appropriately readable.

  Here, the storage unit 260 stores a voltage adjustment unit 261, a gap measurement unit 262, a light amount recognition unit 263, and a measurement unit 264 as programs. Note that the gap measuring unit 262 may be omitted as described above.

  The storage unit 260 also includes voltage table data 265 shown in FIG. 7 in which voltage values to be applied to the electrostatic actuators 80 and 90 in order to adjust the interval of the first gap G1 and the time to apply the voltage values are associated. Is remembered.

  The color measurement control device 204 is connected to the spectroscopic measurement device 203 and the light source device 202, and controls the light source device 202 and performs a color measurement process based on the spectral characteristics acquired by the spectroscopic measurement device 203. As the color measurement control device 204, for example, a general-purpose personal computer, a portable information terminal, or a computer dedicated to color measurement can be used.

  As shown in FIG. 18, the colorimetric control device 204 includes a light source control unit 272, a spectral characteristic acquisition unit 270, a colorimetric processing unit 271, and the like.

  The light source control unit 272 is connected to the light source device 202. Then, the light source control unit 272 outputs a predetermined control signal to the light source device 202 based on, for example, a user setting input, and causes the light source device 202 to emit white light with a predetermined brightness.

  The spectral characteristic acquisition unit 270 is connected to the spectroscopic measurement apparatus 203 and acquires spectral characteristics input from the spectroscopic measurement apparatus 203.

  The color measurement processing unit 271 performs color measurement processing for measuring the chromaticity of the inspection target A based on the spectral characteristics. For example, the colorimetric processing unit 271 performs processing such as graphing the spectral characteristics obtained from the spectroscopic measurement device 203 and outputting the graph to an output device such as a printer or a display (not shown).

  FIG. 19 is a flowchart showing the spectroscopic measurement operation of the spectroscopic measurement apparatus 203. First, the CPU 250 of the control circuit unit 240 activates the voltage adjustment unit 261, the light amount recognition unit 263, and the measurement unit 264. Further, as an initial state, the CPU 250 initializes the measurement time variable n (sets n = 0) (step S1). The measurement time variable n takes an integer value of 0 or more.

  Thereafter, the measurement unit 264 measures the amount of light transmitted through the etalon 10 in the initial state, that is, in a state where no voltage is applied to the electrostatic actuators 80 and 90 (step S2). Note that the size of the first gap G1 in the initial state may be measured in advance when the spectroscopic measurement device is manufactured and stored in the storage unit 260, for example. Then, the light amount of the transmitted light in the initial state obtained here and the size of the first gap G1 are output to the colorimetric control device 204.

  Next, the voltage adjustment unit 261 reads the voltage table data 265 stored in the storage unit 260 (step S3). Further, the voltage adjusting unit 261 adds “1” to the measurement time variable n (step S4).

  Thereafter, the voltage adjustment unit 261 acquires voltage data and voltage application period data of the first and second electrodes 62 and 64 corresponding to the measurement time variable n from the voltage table data 265 (step S5). Then, the voltage adjustment unit 261 outputs a drive control signal to the drive circuit 230, and performs a process of driving the electrostatic actuators 80 and 90 according to the data of the voltage table data 265 (step S6).

  In addition, the measurement unit 264 performs a spectroscopic measurement process at the application time lapse timing (step S7). That is, the measurement unit 264 causes the light amount recognition unit 263 to measure the amount of transmitted light. In addition, the measurement unit 264 performs control to output a spectroscopic measurement result in which the measured amount of transmitted light is associated with the wavelength of transmitted light to the colorimetric control device 204. In the measurement of the light quantity, the light quantity data of a plurality of times or all the times is stored in the storage unit 260, and after obtaining the light quantity data for every plural times or the data of all the light quantities, the respective light quantities are collectively collected. May be measured.

  Thereafter, the CPU 250 determines whether or not the measurement time variable n has reached the maximum value N (step S8). When the CPU 250 determines that the measurement time variable n is N, the series of spectroscopic measurement operations are terminated. On the other hand, if the measurement time variable n is less than N in step S8, the process returns to step S4, a process of adding “1” to the measurement time variable n is performed, and the processes of step S5 to step S8 are repeated.

3. Optical Device FIG. 20 is a block diagram showing a schematic configuration of a transmitter of a wavelength division multiplexing communication system which is an example of an optical device according to an embodiment of the present invention. In wavelength division multiplexing (WDM) communication, if multiple signals with different wavelengths are used in a single optical fiber by using the characteristic that signals with different wavelengths do not interfere with each other, The amount of data transmission can be improved without increasing the number of lines.

  20, the wavelength division multiplexing transmitter 300 includes an optical filter 10 on which light from a light source 301 is incident, and light having a plurality of wavelengths λ0, λ1, λ2,. Transmitters 311, 312, and 313 are provided for each wavelength. The optical pulse signals for a plurality of channels from the transmitters 311, 312, and 313 are combined into one by the wavelength multiplexing device 321 and transmitted to one optical fiber transmission line 331.

  The present invention can be similarly applied to an optical code division multiplexing (OCDM) transmitter. This is because OCDM identifies channels by pattern matching of encoded optical pulse signals, but the optical pulses constituting the optical pulse signals include optical components having different wavelengths.

  Although several embodiments have been described above, it is easily understood by those skilled in the art that many modifications can be made without departing from the novel matters and effects of the present invention. Accordingly, all such modifications are intended to be included in the scope of the present invention. For example, a term described at least once together with a different term having a broader meaning or the same meaning in the specification or the drawings can be replaced with the different term in any part of the specification or the drawings.

  10 optical filter (etalon), 20 first substrate, 20A1 first facing surface, 20A2 second facing surface, 30 second substrate, 30A facing surface, 40 first reflecting film, 50 second reflecting film, 60 lower electrode, 62 First electrode, 62A first circular electrode portion, 62B first lead wire, 64 second electrode, 64A second ring electrode portion, 64B second lead wire, 64C first slit, 70, 70 ′ upper electrode, 72 Third electrode, 72A Third ring electrode portion, 74, 74 'Fourth electrode, 74A, 74A' Fourth ring electrode portion, 76A Third lead wire, 76B Fourth lead wire, 78 Second slit, 80th 1 gap variable drive part (electrostatic actuator), 90 2nd gap variable drive part (electrostatic actuator), 101-104 1st-4th external connection electrode, DESCRIPTION OF SYMBOLS 10 Potential difference control part, 112 1st electrode drive part, 114 2nd electrode drive part, 116 Digital control part, 120 Power supply, 200 Analysis apparatus (colorimeter), 300 Optical apparatus, G1 1st gap, G21 2nd gap, G22 3rd gap, L center line, ΔVseg1 inner circumference side potential difference, ΔVseg2 outer circumference side potential difference, W1, W2 ring width.

Claims (19)

A first substrate;
A second substrate facing the first substrate;
A first electrode provided on the first substrate;
A first reflective film provided on the first electrode;
A second reflective film provided on the second substrate and facing the first reflective film;
A second electrode provided on the first substrate and formed around the first electrode in a plan view in the thickness direction of the first substrate;
A third electrode provided on the second substrate, formed around the second reflective film in a plan view in the thickness direction of the second substrate, and facing the first electrode;
A fourth electrode provided on the second substrate and facing the second electrode;
An optical filter comprising: In claim 1,
The first electrode and the second electrode are electrically independent,
The optical filter, wherein the third electrode and the fourth electrode are electrically connected through a connection portion. In claim 1 or 2,
A first wiring connected to the first electrode;
A second wiring connected to the second electrode;
Further including
Before Stories second electrode has a first ring shape having a first slit,
A part of said 1st wiring is formed in the area | region in which the said 1st slit was formed, The optical filter characterized by the above-mentioned. In claim 3,
The third electrode has a second ring shape;
The optical filter, wherein the fourth electrode has a third ring shape. In claim 3,
The third electrode has a second ring shape;
The fourth electrode has a third ring shape having a second slit,
The optical filter, wherein the second slit overlaps the first slit in a plan view. In any one of claims 3 to 5,
A third wiring connected to the third electrode;
A fourth wiring connected to the third electrode;
An optical filter further comprising: In claim 6,
The first substrate has a first imaginary straight line and a second imaginary straight line that intersects the first imaginary straight line in a plan view;
The first wiring extends in a first direction along the first imaginary straight line,
The second wiring extends in a second direction along the first imaginary straight line and opposite to the first direction,
The third wiring extends in a third direction along the second imaginary straight line,
The optical filter, wherein the fourth wiring extends along a second imaginary straight line and in a fourth direction that is opposite to the third direction. In any one of Claims 1 thru | or 7,
Before SL ring width of the fourth electrode, the light filter being larger than the ring width of the third electrode. In any of claims 1 to 8,
The second substrate has a first part and a second part thinner than the film thickness of the first part,
The second reflective film is formed on the first portion of the second substrate;
The optical filter, wherein the third electrode and the fourth electrode are formed on the second portion of the second substrate. In any one of Claim 1 thru | or 9,
The first substrate has a first surface and a second surface;
The distance between the first surface and the second substrate is longer than the distance between the second surface and the second substrate,
The first reflective film is formed on the first surface,
The optical filter, wherein the second electrode is formed on the second surface. In any one of Claims 1 thru | or 10,
An optical filter, further comprising: a potential difference control unit that controls a potential difference between the first electrode and the third electrode and a potential difference between the second electrode and the fourth electrode. In claim 11,
The potential difference control unit sets the potential difference between the first electrode and the third electrode to the second potential difference after setting the potential difference between the second electrode and the fourth electrode to the first potential difference. A light filter characterized by that. In claim 12,
The optical filter according to claim 1, wherein the potential difference control unit sets the second potential difference in a state where the potential difference control unit is set to the first potential difference. In claim 11,
The potential difference control unit
Setting the potential difference between the second electrode and the fourth electrode to a first potential difference;
After setting the first potential difference, the potential difference between the second electrode and the fourth electrode is set to a second potential difference larger than the first potential difference,
With the second potential difference set, the potential difference between the first electrode and the third electrode is set to a third potential difference,
After setting the third potential difference, the potential difference between the first electrode and the third electrode is set in the state where the potential difference between the second electrode and the fourth electrode is set to the second potential difference. An optical filter characterized by being set to a fourth potential difference larger than the third potential difference. In claim 14,
The period set for the second potential difference is longer than the period set for the first potential difference,
An optical filter characterized in that a period set for the fourth potential difference is longer than a period set for the third potential difference. In claim 11,
The potential difference control unit
Setting the potential difference between the second electrode and the fourth electrode to a first potential difference;
After setting the first potential difference, the potential difference between the second electrode and the fourth electrode is set to a second potential difference larger than the first potential difference,
After setting the second potential difference, the potential difference between the second electrode and the fourth electrode is set to a third potential difference larger than the second potential difference;
With the third potential difference set, the potential difference between the first electrode and the third electrode is set to a fourth potential difference,
After setting the fourth potential difference, the potential difference between the first electrode and the third electrode is set in the state where the potential difference between the second electrode and the fourth electrode is set to the third potential difference. Set the fifth potential difference greater than the fourth potential difference,
After setting the fifth potential difference, the potential difference between the first electrode and the third electrode is set in the state where the potential difference between the second electrode and the fourth electrode is set to the third potential difference. Set the sixth potential difference greater than the fifth potential difference,
The absolute value of the difference between the second potential difference and the third potential difference is smaller than the absolute value of the difference between the first potential difference and the second potential difference;
The optical filter, wherein an absolute value of a difference between the fifth potential difference and the sixth potential difference is smaller than an absolute value of a difference between the fourth potential difference and the fifth potential difference. An optical filter according to any one of claims 1 to 16, and a light receiving element that receives light transmitted through the optical filter,
Including optical filter module.   An analytical instrument comprising the optical filter according to claim 1.   An optical device comprising the optical filter according to claim 1.

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