JP6798566B2 - Optical filter and optical filter module, analytical equipment and optical equipment - 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 gaps at regular intervals. ) And a pair of electrostatically driven electrodes for controlling the gap. Such a wavelength variable interference filter can generate an electrostatic attraction by a voltage applied to an electrostatic drive electrode, control a gap, and change the central wavelength of transmitted light.

JP-A-11-142752

However, in such a tunable interference filter, it is difficult to accurately obtain the gap amount due to fluctuations in the drive voltage due to noise or the like.

An object of the present invention is to provide an optical filter and an optical filter module, and an analytical instrument and an optical instrument that can accurately obtain a gap amount.

(1) The optical filter according to one aspect of the present invention is
1st board and
A second substrate facing the first substrate and
The first reflective film provided on the first substrate and
A second reflective film provided on the second substrate and facing the first reflective film, and
A first electrode provided on the first substrate and formed around the first reflective film in a plan view,
A second electrode provided on the first substrate and formed around the first electrode in a plan view,
A third electrode provided on the second substrate and facing the first electrode, and
It is characterized by including a fourth electrode provided on the second substrate and facing the second electrode.

According to one aspect of the present invention, it has 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. As a result, as will be described later, the gap amount can be obtained more accurately than in the form 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 and are electrically independent.
The third electrode and the fourth electrode are electrically connected to each other via a connecting portion.

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

(3) In one aspect of the present invention
The first wiring connected to the first electrode and
Further including a second wiring connected to the second electrode,
The first electrode has a first ring shape and has a first ring shape.
The second electrode has a second ring shape having a first slit.
Since the second electrode has a second ring shape having the first slit, the first wiring can be pulled out from the first electrode through the first slit.

(4) In one aspect of the present invention
The third electrode has a third ring shape and has a third ring shape.
The fourth electrode is characterized by having a fourth ring shape.

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

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

In a 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 region of the first slit. As a result, even if a voltage is applied to the first wiring, it is possible to suppress the generation of an unnecessary electrostatic attraction between the first wiring and the fourth electrode.

(6) In one aspect of the present invention
With the third wiring connected to the third electrode,
It is characterized by further including a fourth wiring connected to the third electrode.

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

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

By forming the first wiring, the second wiring, the third wiring, and the fourth wiring in this way, the parasitic capacitance between these wirings can be reduced.

(8) In one aspect 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 close to the joint portion between the first substrate and the second substrate, an electrostatic attraction force larger than the electrostatic attraction force between the first electrode and the second electrode is required. Therefore, by increasing the ring width of the second electrode and the fourth electrode, a large electrostatic attraction can be generated.

(9) In one aspect of the present invention,
The second substrate has a first portion and a second portion thinner than the film thickness of the first portion.
The second reflective film is formed on the first portion of the second substrate.
The third electrode and the fourth electrode are characterized in that they are formed on 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 aspect of the present invention
The first substrate has a first surface and a second surface lower than the first surface.
The first reflective film is formed on the first surface and is formed on the first surface.
The first electrode and the second electrode are characterized in that they are formed on the second surface.

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

As a result, the gap control can be easily performed as described later.

(13) In one aspect of the present invention,
The potential difference control unit is characterized in that it is set to the second potential difference in a state of being 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 described later.

(14) In one aspect of the present invention
The potential difference control unit
The potential difference between the second electrode and the fourth electrode is set as the first potential difference.
After setting to 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.
In the state of being set to the second potential difference, the potential difference between the first electrode and the third electrode is set to the third potential difference.
After setting the third potential difference, the potential difference between the first electrode and the third electrode is set to the second potential difference in a state where the potential difference between the second electrode and the fourth electrode is set to the second potential difference. It is characterized in that the fourth potential difference is set to be larger than the third potential difference.

As a result, the gap can be controlled in more stages. Further, since the first potential difference is set to the second potential difference larger than the first potential difference and the third potential difference is set to the fourth potential difference larger than the third potential difference, rapid 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.

This makes it possible to stabilize at a desired gap interval, as will be described later.

(16) In one aspect of the present invention
The potential difference control unit
The potential difference between the second electrode and the fourth electrode is set as the first potential difference.
After setting to 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 to 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.
In the state of being set to the third potential difference, the potential difference between the first electrode and the third electrode is set to the fourth potential difference.
After setting the fourth potential difference, the potential difference between the first electrode and the third electrode is set to the third potential difference in a state where the potential difference between the second electrode and the fourth electrode is set to the third potential difference. Set to the 5th potential difference larger than the 4th potential difference,
After setting the fifth potential difference, the potential difference between the first electrode and the third electrode is set to the third potential difference in a state where the potential difference between the second electrode and the fourth electrode is set to the third potential difference. Set to the 6th potential difference larger than the 5th 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.

This makes it possible to stabilize at a desired gap interval, as will be described later.

(17) The optical filter module according to one aspect of the present invention is
It includes a light receiving element that receives light transmitted through the above-mentioned optical filter.

(18) The analytical instrument according to one aspect of the present invention is
Includes the optical filters described above.

(19) The optical device according to one aspect of the present invention is
Includes the optical filters described above.

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. 4 (A) and 4 (B) 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 to 4th lead-out wiring by seeing through the 2nd board from the 2nd board side. It is a block diagram of the applied voltage control system of an optical filter. It is a characteristic diagram which shows an example of voltage table data. It is a timing chart of voltage application realized according to the voltage table data. It is a characteristic diagram which shows the relationship between the gap between the 1st and 2nd reflective films of an optical filter, and the transmission peak wavelength. It is a characteristic figure which shows the relationship between the potential difference between the 1st and 2nd electrodes, and electrostatic attraction. It is a characteristic diagram which shows the data of an Example about a potential difference, a gap and a variable wavelength shown in FIG. 7. It is a characteristic diagram which shows the relationship between the applied voltage and a gap shown in FIG. It is a characteristic diagram which shows the relationship between the applied voltage and a transmission peak wavelength shown in FIG. 14 (A) and 14 (B) are plan views showing the first and second electrodes of the comparative example. It is a characteristic diagram which shows the data of the comparative example about a potential difference, a gap and a variable wavelength. It is a characteristic diagram which shows the relationship between the applied voltage and a gap shown in FIG. It is a characteristic diagram which shows the relationship between the applied voltage and a transmission peak wavelength shown in FIG. It is sectional drawing which shows the voltage non-application state of the optical filter which concerns on other embodiment of this invention. It is a block diagram of the analyzer which is still another embodiment of this invention. It is a flowchart which shows the spectroscopic measurement operation in the apparatus shown in FIG. It is a block diagram of the optical device which is still another embodiment of this invention.

Hereinafter, preferred embodiments of the present invention will be described in detail. It should be noted that the present embodiment described below does not unreasonably limit the content of the present invention described in the claims, and all the configurations described in the present embodiment are indispensable as a means for solving the present invention. Not always.

1. 1. Optical filter 1.1. Filter part of optical filter 1.1.1. Outline of Filter Section FIG. 1 is a cross-sectional view of the optical filter 10 of the present embodiment in a voltage-free state, and FIG. 2 is a cross-sectional view of the optical filter 10 in a voltage-applied 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 the present embodiment, for example, a support portion 22 that movably supports the second substrate 30 is formed integrally with the first substrate 20. The support portion 22 may be provided on the second substrate 30, or may be formed separately from the first and second substrates 20, 30.

The first and second substrates 20 and 30, respectively, are formed of various glasses such as soda glass, crystalline glass, quartz glass, lead glass, potassium glass, borosilicate glass, and non-alkali glass, and crystals. .. Among these, as the constituent material of the substrates 20 and 30, for example, glass containing an alkali metal such as sodium (Na) or potassium (K) is preferable, and the substrates 20 and 30 are formed from such glass. Therefore, it is possible to improve the adhesion of the reflective films 40 and 50 and the electrodes 60 and 70, which will be described later, and the bonding strength between the substrates. Then, these two substrates 20 and 30 are integrated by being bonded by, for example, surface activation bonding using a plasma polymerized film. Each of the first and second substrates 20 and 30 is formed into a square having a side of, for example, 10 mm, and the maximum diameter of the portion that functions 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 reflective film 40 is formed on the central first facing surface 20A1 of the facing surfaces facing the second substrate 30. 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 reflective film 50 facing the first reflective film 40 is formed at the center position of the facing surface 30A facing the first substrate 20.

The first and second reflective films 40 and 50 are formed in a circular shape having a diameter of, for example, about 3 mm. The first and second reflective films 40 and 50 are reflective films formed by an AgC single layer, and can be formed on the first and second substrates 20 and 30 by a method such as sputtering. The film thickness dimension of the AgC single-layer reflective film is formed to be, for example, 0.03 μm. In the present embodiment, an example in which an AgC single-layer reflective film capable of dispersing the entire visible light region is used as the first and second reflective films 40 and 50 is shown, but the present invention is not limited to this, and the spectroscopic wavelength range is narrow. , A dielectric multilayer film in which a laminated film of TiO ₂ and SiO ₂ is laminated is used, for example, which has a higher transmittance of dispersed light, a narrower half-value width of the transmittance, and better resolution than an AgC single-layer reflective film. You may.

Further, on the surfaces of the first and second substrates 20 and 30 opposite to the facing surfaces 20A1, 20A2 and 30A, antireflection films (not shown) are located at positions corresponding to the first and second reflective films 40 and 50. AR) can be formed. This antireflection film is formed by alternately laminating low refractive index films and high refractive index films, and lowers the reflectance of visible light at the interfaces of the first and second substrates 20 and 30 to reduce the transmittance. Increase.

The first and second reflective films 40 and 50 are arranged so as to face each other via the first gap G1 in the voltage non-applied state shown in FIG. In the present embodiment, the first reflective film 40 is a fixed mirror and the second reflective film 50 is a movable mirror. However, depending on the above-described first and second substrates 20 and 30, the first and first reflective films are used. 2 Either one or both of the reflective films 40 and 50 can be made movable.

For example, a lower electrode 60 is formed on the second facing surface 20A2 around the first facing surface 20A1 of the first substrate 20, which is a position around the first reflective film 40 in a plan view. Similarly, the facing surface 30A of the second substrate 30 is provided with the upper electrode 70 facing the lower electrode 60. The lower electrode 60 and the upper electrode 70 are arranged to face each other via the second gap G2. The surfaces of the lower and upper electrodes 60 and 70 can be covered with an insulating film.

In the present embodiment, the surfaces of the first substrate 20 facing the second substrate 30 are arranged around the first facing surface 20A1 on which the first reflective film 40 is formed and the first facing surface 20A1 in a plan view. It has a second facing surface 20A2 on which the lower electrode 60 is formed. The first facing surface 20A1 and the second facing surface 20A2 may be the same surface, but 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 The 20A1 is set at a position closer to the second substrate 30 than the second facing surface 20A2. As a result, the relationship of the first gap G1 <the second gap G2 is established.

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 in the present embodiment, the lower electrode 60 has the first and second electrodes 62 and 64 as an example of K = 2. That is, while the K segment electrodes 62 and 64 can be set to different voltages, 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 do not have to be common electrodes having the same potential, and the third electrode 72 and the fourth electrode 74 have a structure in which they 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. 4 (A). Further, in the structure of the lower electrode 60 and the upper electrode 70, 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 can be controlled independently. It should be. In the case of K ≧ 3, the relationship described below with respect to the first and second electrodes 62 and 64 can be applied to any two segment electrodes adjacent to each other.

In the optical filter 10 having such a structure, the first and second substrates 20 and 30 both have a region where a reflective film (first and second reflective films 40 and 50) is formed and an electrode (lower and upper electrodes 60). , 70) is formed in a region different from that in a plan view, and the reflective film and the electrode are not laminated as in Patent Document 1. Therefore, even if at least one of the first and second substrates 20 and 30 (the second substrate 30 in this embodiment) is a movable substrate, the movable substrate can be easily bent because the reflective film and the electrode are not laminated. .. Moreover, unlike Patent Document 1, since a reflective film is not formed on the lower and upper electrodes 60 and 70, even if the optical filter 10 is used as a transmission type or reflection type wavelength variable interference filter, the lower and upper electrodes 60 There is no restriction that, 70 is a transparent electrode. Since even a transparent electrode affects the transmission characteristics, the optical filter 10 which is a transmission type tunable interference filter is desired because no reflective film is formed on the lower and upper electrodes 60 and 70. Transmission characteristics are obtained.

Further, in the optical filter 10, a common voltage (for example, a ground voltage) is applied to the upper electrode 70 arranged around the second reflective film 50 in a plan view, and the optical filter 10 is arranged around the first reflective film 40 in a plan view. By applying individually independent voltages of the K segment electrodes 62 and 64 constituting the lower electrode 60 and applying an electrostatic attraction indicated by an arrow between the counter electrodes as shown in FIG. 2, the first , The first gap G1 between the second reflective films 40 and 50 is changed so that the gap is smaller than the size of the initial gap.

That is, as shown in FIG. 2 showing the optical filter 10 in the voltage applied state, the first gap variable drive unit (electrostatic actuator) 80 composed of the first electrode 62 and the upper electrode 70 facing the first electrode 62, and the second electrode 64. The second gap variable drive unit (electrostatic actuator) 90 composed of the upper electrode 70 facing the upper electrode 70 and the upper electrode 70 facing the same are independently driven.

As described above, by having a plurality of (K) variable variable drive units 80 and 90 independently arranged only around the first and second reflective films 40 and 50 in a plan view, the K segment electrodes 62. By changing two parameters, the magnitude of the voltage applied to, 64 and the number of segment electrodes selected to apply the voltage from the K segment electrodes 62, 64, the first and second The size of the gap between the reflective films 40 and 50 is controlled.

As in Patent Document 1, it has been difficult to achieve both a large gap movable range and low sensitivity to voltage fluctuations due to noise or the like only when the parameter is only the type of voltage. As in the present embodiment, by adding a parameter called the number of electrodes, the same applied voltage range as in the case of controlling only by voltage is applied to each segment electrode, so that finer adjustment can be made in a large gap movable range. It is possible to finely adjust the gap by generating an electrostatic attraction.

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

In this way, if the minimum voltage change amount ΔVkmin can be secured to a large extent, the gap fluctuation is small even if the voltage applied to the K first and second electrodes 62 and 64 fluctuates slightly due to power supply fluctuation 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 becomes possible, and it is not always necessary to perform feedback control of the gap as in Patent Document 1. Further, even if the gap is feedback-controlled, it can be stabilized at an early stage because the sensitivity to noise is small.

In the present embodiment, in order to secure 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, for example, a thin portion 34 having a thickness dimension of about 50 μm. .. The thin portion 34 is formed thinner than the thick portion 32 in the region where the second reflective film 50 is arranged 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 arranged. A thin portion 34 is formed in the second region where the upper electrode 70 is formed. In this way, the thin-walled portion 34 makes it difficult for the thick-walled portion 32 to bend while ensuring the flexibility, so that the second reflective film 50 can maintain the flatness and change the gap.

In the present embodiment, each of the plurality of independent (K) variable variable drive units is composed of 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. You may. However, the electrostatic actuator that applies the attractive force in a non-contact manner has less interference between a plurality of variable gap drive units, and is suitable for controlling the gap with high accuracy. On the other hand, for example, when two piezoelectric elements are arranged between the first and second substrates 20 and 30, the undriven piezoelectric element prevents the gap displacement due to the other driven piezoelectric element. Etc., which causes an adverse effect on the method of independently driving a plurality of variable gap drive units. From this point of view, it is preferable that the plurality of variable gap drive units are composed of 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. 3A. That is, the first electrode 62 has a first ring-shaped electrode portion 62A, the second electrode 64 has a second ring-shaped electrode portion 64A outside the ring-shaped electrode portion 62A, and the ring-shaped electrode portions 62A and 64A respectively. Is formed concentrically with respect to the first reflective film. The term "ring shape" or "ring shape" is a term that includes not only an endless ring but also a discontinuous ring shape, and includes not only a circular ring but also a rectangular ring or a polygonal ring.

Then, as shown in FIG. 2, each of the first and second electrodes 62 and 64 is axisymmetrically arranged with respect to the center line L of the first reflective film 40. As a result, the electrostatic attraction forces F1 and F2 acting between the lower and upper electrodes 60 and 70 when a voltage is applied act line-symmetrically with respect to the center line L of the first reflective film 40, so that the first and second reflections occur. 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 wider than the ring width W1 of the first electrode 62 (W2> W1). This is because the electrostatic attraction is proportional to the electrode area, and the electrostatic attraction F2 generated by the second electrode 64 is required to be larger than the electrostatic attraction F1 generated by the first electrode 62. More specifically, the outer second electrode 64 is provided closer to the substrate support portion 22 that functions as a hinge portion than the first electrode 62. Therefore, the second electrode 64 needs to generate a large electrostatic attraction F2 that resists the resistance force at the hinge portion 22. The outer second electrode 64 has a larger diameter than the inner first electrode 62, and the area of the second electrode 64 is larger even if the width W1 = the width W2. Therefore, the width W1 = the width W2 may be set, but by further expanding the ring width W2, the area is further increased and a large electrostatic attraction F2 can be generated. In particular, as will be described later, when the outer second electrode 64 is driven before the inner first electrode 62, the initial gap G2 between the second electrode 64 and the upper electrode 70 is large. It is also advantageous in that the area of the two electrodes 64 can be widened to generate a large electrostatic attraction F2. In that case, when the inner first electrode 62 is driven, the gap is small as long as the driving state of the second electrode 64 is maintained, so that even if the ring width W1 of the first electrode 62 is small, there is an adverse effect on driving. There is no.

Here, the first lead-out wiring 62B is connected to the first electrode 62, and the second lead-out electrode 64B is connected to the second electrode 64. These first and second extraction electrodes 62B and 64B are formed extending from the center of the first reflection film 40 in the radial direction, for example. A first slit 64C is provided so that the second ring-shaped electrode portion 64A of the second electrode 64 is discontinuous. The first lead-out wiring 62B extending from the inner first electrode 62 is drawn out of the second electrode 64 through the first slit 64C formed in the outer second electrode 64.

In this way, when the first and second electrodes 62 and 64 are ring-shaped electrode portions 62A and 64A, respectively, the first electrode 62 inside the first slit 64C2 formed in the second electrode 64 on the outside The take-out path of the first lead-out wiring 62B can be easily secured.

1.1.3. Upper electrode The upper electrode 70 arranged on the second substrate 30 includes a region of the second substrate 30 facing the lower electrode 60 (first, second electrodes 62, 64) formed on the first substrate 20. It can be formed in the area. When the upper electrode 70 is a common electrode set to the same voltage, it may be a solid electrode, for example.

Instead of this, the upper electrode 70 arranged 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 like the lower electrode 60. .. The K segment electrodes can also be arranged concentrically with respect to the center of the second reflective film 50. By doing so, the electrode area formed on the movable second substrate 30 is reduced to the minimum necessary, so that the rigidity of the second substrate 30 is lowered and the flexibility can be ensured.

The K segment electrodes constituting the upper electrode 70 can have a third electrode 72 and a fourth electrode 74, as shown in FIGS. 1, 2 and 3 (B). The third electrode 72 has a third ring-shaped electrode portion 72A, the fourth electrode 74 has a fourth ring-shaped electrode portion 74A outside the third ring-shaped electrode portion 62A, and the ring-shaped electrode portions 72A and 74A respectively. Is formed concentrically with respect to the second reflective film. The meaning of "concentric ring" is the same as that for the lower electrode 60. The third electrode 72 faces 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 (same as the ring width W1 of the first electrode 62).

Further, the third and fourth electrodes 72 and 74 may be electrically connected to each other and set to the same potential. In this case, for example, the third and fourth extraction electrodes 76A and 76B are formed extending from the center of the second reflective film 50 in the radial direction. Each of the third and fourth extraction electrodes 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 one lead-out electrode, but the wiring resistance is reduced by using a plurality of lead-out electrodes to reduce the wiring resistance of the common electrode. The charge / discharge speed can be increased. When the third and fourth electrodes 72 and 74 have a structure in which they are electrically independent, a lead-out electrode is formed on each electrode.

1.1.4. Polymerization region of the lower and upper electrodes FIG. 4 (A) shows an overlapping state of the lower and upper electrodes 60 and 70 of the present embodiment in a plan view as viewed from the second substrate 30 side. In FIG. 4A, the lower electrode 60 located on the lower side has a second substrate because the first and second electrodes 62 and 64 face the third and fourth electrodes 72 and 74 of the second electrode. It does not appear in the plan view seen from the 30 side. As for the lower electrode 60 located on the lower side, only the first and second lead-out wirings 62B and 64B appear in a plan view seen from the second substrate 30 side as shown by hatching. In the first lead-out wiring 62B, since the third 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 third 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 the first slit 64C, so that the second electrode 64 is applied to the second electrode 64 in the region of the slit 64C. The voltage-based electrostatic attraction F2 (see FIG. 2) does not work.

On the other hand, since the first lead-out wiring 62B is arranged in the first slit 64C as shown in FIG. 3A, the first lead-out wiring 62B having the same potential as the inner first electrode 62 and the outer first lead-out wiring 62B An electrostatic attraction 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 an even electrostatic attraction.

FIG. 4B shows an overlapping state of the lower and upper electrodes 60 and 70', which are modified examples, in a plan view when viewed from the second substrate 30 side. The difference between the upper electrode 70'of FIG. 4 (B) and the upper electrode 70 of FIG. 4 (A) is that the fourth electrode 74 has a fourth ring shape at a position facing the first slit 64C of the lower electrode 60. It is a point that further has a second slit 78 that discontinues the electrode portion 74A'. In other respects, the upper electrode 70'of FIG. 4 (B) is the same as the upper electrode 70 of FIG. 4 (A).

In this case, the electrode facing the first lead-out wiring 62B does not exist. Therefore, for example, when the inner first electrode 62 is driven, an unnecessary electrostatic attraction acting between the first lead-out wiring 62B having the same potential as the inner first electrode 62 and the outer fourth electrode 74'is generated. , It is possible to prevent the occurrence in the first slit 64C.

1.1.5. The lead-out wiring FIG. 5 is a plan view of the second board 30 as seen through from the second board 30 side, and shows the wiring layouts of the first to fourth lead-out wires 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 the first and second diagonal lines. In the present embodiment, each of the first and second substrates 20 and 30 is formed into a square having a side of, for example, 10 mm. When the direction in which the first lead-out wiring 62B extends from the first electrode 62A along the first diagonal line is the first direction D1, the second lead-out wiring 64B is in the direction opposite to the first direction D1 on the first diagonal line. It extends in the second direction D2. The third lead-out wiring 76A extends in the third direction D3 along the second diagonal line. The fourth lead-out wiring 76B extends in the fourth direction D4 on the second diagonal line, which is opposite to the third direction D3. Then, the first to fourth connection electrode portions 101 to 104 to which the first to fourth lead-out wirings 62B, 64B, 76A, and 76B are connected are provided at the positions of the four corners of the rectangular substrates 20 and 30 in a plan view. ing.

Then, first, the first and second lead-out wirings 62B and 64B formed on the first substrate 20 and the third and fourth lead-out wirings 76A and 76B formed on the second substrate 30 overlap each other in a plan view. It does not form a parallel electrode. Therefore, unnecessary electrostatic attraction is unlikely to occur between the first and second lead-out wirings 62B and 64B and the third and fourth lead-out wirings 76A and 76B, and wasteful capacity can be reduced. Further, the wiring lengths of the first to fourth lead-out wirings 62B, 64B, 76A, and 76B leading to the first to fourth connection electrode portions 101 to 104 are the shortest. Therefore, the wiring resistance and wiring capacitance of the first to fourth lead-out 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.

In the structure of the first to fourth lead-out wires 62B, 64B, 76A, and 76B, the first substrate has a first virtual straight line and a second virtual straight line intersecting with the first virtual straight line in a plan view. The first lead-out wire 62B extends in the first direction along the first virtual straight line, and the second lead-out wire 64B extends in the second direction along the first virtual straight line and in the direction opposite to the first direction. The third lead-out wire 76A extends in the third direction along the second virtual straight line, and the fourth lead-out wire 76B extends along the second virtual straight line and in the direction opposite to the third direction. It may extend 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, 30. When 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-out wiring arranged on the other of the first and second substrates 20 and 30 is provided. Can be connected to the external connection electrode portion formed on one of the substrates by a conductive paste or the like. The first to fourth external connection electrode portions 101 to 104 are connected to the outside via a connection portion such as a lead wire or wire bonding.

Further, the first to fourth lead-out wirings 62B, 64B, 76A, and 76B may intersect with, for example, a plasma polymerized film that joins the first and second substrates 20, 30. Alternatively, the first to fourth lead-out wirings 62B, 64B, 76A, 76B may be 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 the applied voltage control system block FIG. 6 is a block diagram of the applied voltage control system of the optical filter 10. As shown in FIG. 6, the optical filter 10 has a potential difference control unit 110 that controls the potential difference between the lower electrode 60 and the upper electrode 70. In the present embodiment, the upper electrode 70 (third and fourth electrodes 72, 74), which is a common electrode, is fixed to a constant common voltage, for example, the ground voltage (0V), so that the potential difference control unit 110 is the lower electrode 60. By changing the voltage applied to the first and second electrodes 62 and 64, which are the K segment electrodes constituting the above, the inner peripheral side between each of the first and second electrodes 62 and 64 and the upper electrode 70 The potential difference ΔVseg1 and the outer peripheral side potential difference ΔVseg2 are controlled, respectively. A common voltage other than the ground voltage may be applied to the upper electrode 70, and in that case, the potential difference control unit 110 may control the application / non-application of the common voltage to the upper electrode 70.

In FIG. 6, the potential difference control unit 110 is a first electrode driving unit connected to the first electrode 62, for example, a first digital-analog converter (DAC1) 112, and a second electrode driving unit connected to the second electrode 64, for example. It includes a second digital-analog converter (DAC2) 114 and a digital control unit 116 that controls them, for example digitally. The voltage from the power supply 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 voltage supplied from the power supply 120 and output the analog voltage corresponding to the digital value from the digital control unit 116. As the power supply 120, an analytical instrument or an optical device equipped with the optical filter 10 can be used, but a power source dedicated to the optical filter 10 may be used.

1.2.2. A method of driving an optical filter FIG. 7 is a characteristic diagram showing an example of voltage table data which is the original data of control by the digital control unit 116 shown in FIG. This voltage table data may be provided in the digital control unit 116 itself, or may be provided in an analytical device or an optical device to which the optical filter 10 is mounted.

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

The potential difference control unit 110 sets the voltage value set for each of the K segment electrodes (1st and 2nd electrodes 62 and 64) according to the voltage table data shown in FIG. 7, and sets the voltage value to the K segment electrodes (1st and 1st). It is applied to each of the two electrodes 62 and 64). FIG. 8 is a voltage application timing chart realized by driving the voltage table data shown in FIG. 7 in the order of data numbers.

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 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 (N = L + M =) of g0 to g8. 9) It is variable in stages.

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

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

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

As shown in FIG. 7, the potential difference control unit 110 first sequentially applies voltages VO1 to voltage 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 as follows: first potential difference VO1, second potential difference VO2, third potential difference VO3, fourth potential difference VO4, fifth potential difference VO5. , The outer peripheral side potential difference Vseg2 can be sequentially increased. As a result, the size of the first gap G1 between the first and second reflective films 40 and 50 is gradually narrowed in the order of go → g1 → g2 → g3 → g4. As a result, the light that passes through the optical filter 10, that is, the transmission peak wavelength changes in the order of λ0 → λ1 → λ2 → λ3 → λ4.

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, while 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 0 V, 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 side 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 becomes smaller in the order of g5 → g6 → g7 → g8. As a result, the light transmitted through the optical filter 10, that is, the transmitted peak wavelength changes in the order of λ5 → λ6 → λ7 → λ8 so as to be sequentially shortened.

The potential difference control unit 110 switches the outer peripheral side potential difference Vseg2 from at least the first potential difference VO1 to the second potential difference VO2 larger than the first potential difference VO1 and further to the third potential difference VO3 larger than the second potential difference VO2, and switches the inner peripheral side potential difference VO3. For Vseg1, at least, in order to switch from the first potential difference VI1 to the second potential difference VI2 larger than the first potential difference VI1 and further to the third potential difference VI3 larger than the second potential difference VI2, the damping free vibration of the second substrate 30 on the movable side is changed. It can be suppressed and a rapid variable voltage operation can be performed. Moreover, the potential difference control unit 110 sets the voltage of at least three values (may include 0) for each of the first and second electrodes 62 and 64, and at least the first segment voltage VI1 with respect to the first electrode 62. , The second segment voltage VI2 and the third segment voltage VI3 are applied to the second electrode 64 at least the first segment voltage VO1, the second segment voltage VO2, and the third segment voltage VO3. Therefore, it is possible to change the gap in three or more steps by simply driving each of the first and second electrodes 62 and 64, and it is not necessary to unnecessarily increase the number of segment electrodes of the lower electrode 60.

1.2.3. Amount of voltage change (absolute value of the difference between the first potential difference and the 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 side potential difference Vseg1 and the outer peripheral side potential difference Vseg2 from the absolute value of the difference between the first potential difference and the second potential difference. It can be made smaller. In the present embodiment, the upper electrode 70 is invariant at a common voltage of 0 V. Therefore, 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. 7 and 8. It 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 FIGS. 7 and 8, the voltage change amount of the outer peripheral side potential difference Vseg2 is in a relationship of gradually decreasing in the order of ΔVO1>ΔVO2>ΔVO3> ΔVO4, and the voltage change amount of the inner peripheral side potential difference Vseg1 is also ΔVI1>ΔVI2> ΔVI3. There is a relationship that gradually decreases.

The reason for making such a relationship is as follows.

The electrostatic attraction F can be expressed as "F = (1/2) ε (V / G) ² S". Here, ε: dielectric constant, V: applied voltage, G: gap between electrodes, S: electrode facing area. From this equation, the electrostatic attraction F is proportional to the square of the potential difference between the lower and upper electrodes 60 and 70 (in this embodiment, the voltage V applied to the lower electrode 60). FIG. 10 is a characteristic diagram (figure of F = V ² ) of the electrostatic attraction F that is proportional to the square of the potential difference V. 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 When the difference ΔV2 between the absolute value and the third potential difference is the same (ΔV1 = ΔV2 in FIG. 10), the increase amount ΔF of the electrostatic attraction force sharply increases from ΔF1 to ΔF2, which causes 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 ΔV2 of the difference between the first potential difference and the second potential difference. As a result, it is possible to suppress a rapid increase in electrostatic attraction when the gap is narrowed, it is possible to further suppress overshoot, and it is possible to realize a faster tunable operation.

1.2.4. Voltage application period The voltage difference control unit 110 sets the second potential difference for each of the inner peripheral side potential difference Vreg1 and the outer peripheral side potential difference Vreg2 to be longer than the period set to the first potential difference and to 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, for the outer peripheral side potential difference Vreg2, the period TO2 of the second potential difference VO1 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. The period of VO2 is longer than TO2, and TO1 <TO2 <TO3 <TO4 <TO5, and so on. Similarly, as shown in FIG. 8, for the inner peripheral side potential difference Vreg1, the period TI2 of the second potential difference VI1 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 is longer than TI2, and 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. Therefore, the time until the second substrate 30 comes to rest becomes long. That is, it takes a long time for the first gap G1 between the first and second reflective films 40 and 50 to stabilize at a fixed position. On the other hand, as in the present embodiment, the period set for the second potential difference is longer than the period set for the first potential difference, and the period set for the third potential difference is set as the second potential difference. By setting it longer than the set period, the first gap G1 can be stabilized at a predetermined value.

1.2.5. Examples of potential difference, gap and variable wavelength FIG. 11 is a characteristic diagram showing data of an example of potential difference, gap and variable wavelength shown in FIG. 7. 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 shown in FIG. 11 and the transmission peak wavelength.

In FIG. 11, the first gap G1 between the first and second reflective films 40 and 50 is maximum in order to change the transmission peak wavelength in nine steps from the maximum transmission peak wavelength λ0 = 700 nm to the minimum wavelength λ8 = 380 nm. The gap is varied from 0 = 300 nm to the minimum gap g8 = 140 nm in 9 steps (see also FIG. 12). Correspondingly, the transmission peak wavelength is varied in 9 steps from the maximum wavelength λ0 to the minimum wavelength λ8 (see also FIG. 13). Moreover, in FIG. 11, by setting the nine-step gab g0 to g8 from the maximum gap g0 to the minimum gap g8 at equal intervals (= 40 nm), the nine-step wavelength λ0 to the maximum wavelength λ0 to the minimum wavelength λ8 λ8 is also evenly spaced (= 40 nm). In this way, by changing the size of the first gap G1 between the first and second reflective films so as to be gradually narrowed by a constant amount, the transmission peak wavelength is also shortened by a constant value.

The potential difference control unit 110 sequentially sets the outer peripheral side potential difference Vseg2 to VO1 = 16.9V, VO2 = 21.4V, VO3 = 25V, VO4 = 27.6V, VO5 = 29.8V, and maintains VO5 = 29.8V. With this, the inner peripheral side 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 attraction F1 based on the inner peripheral side potential difference Vreg1 than the electrostatic attractive force F2 based on the outer peripheral side 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 attraction F1 due to the inner peripheral side potential difference Vreg1 is dominant. Therefore, the gap between the first and second reflective films 40 and 50 does not change according to the outer peripheral side potential difference Vreg2. Therefore, in the present embodiment, first, the outer peripheral side potential difference Vreg2 is changed, and then the inner peripheral side potential difference Vreg1 is changed while maintaining the outer peripheral side potential difference Vreg2 at a constant value.

After the outer peripheral side potential difference Vreg2 reaches the outer peripheral side maximum potential difference VO5, 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. By doing so, it is possible to 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, since the outer peripheral side maximum outer peripheral side potential difference VO5 has already been reached after the inner peripheral side potential difference Vreg1 is applied, it is not necessary to further change the outer peripheral side potential difference Vreg2. Therefore, when the outer peripheral side potential difference Vreg2 is changed, the adverse effect of the dominant electrostatic attraction F2 due to the inner peripheral side potential difference Vreg1 does not occur.

When the potential difference control unit 110 sets the inner peripheral side potential difference Vreg1 to the inner peripheral side maximum potential difference VI4, the first gap G1 between the first and second reflective films 40 and 50 is set to the minimum interval g8. Each of the outer peripheral side maximum potential difference VO5 and the inner peripheral side maximum potential difference VI4 can be 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 = 30V is supplied to the potential difference control unit 110 from the power supply 120 shown in FIG. At this time, the outer peripheral side maximum potential difference VO5 is set to 29.8V which does not exceed the maximum voltage Vmax (30V), and the inner peripheral side maximum potential difference VI4 is also set to 29.3V which does not exceed the maximum voltage Vmax (30V). ing.

In FIG. 11, although there is a slight difference of 0.5 V between the inner peripheral side maximum potential difference VO5 and the inner peripheral side maximum potential difference VI4, it can be said that they are substantially the same. This minute difference obtains transmission peak wavelengths at equal intervals on a full scale (see FIGS. 12 and 13) within a range not exceeding the maximum voltage Vmax (30V) for each of the inner peripheral side potential difference Vreg1 and the outer peripheral side potential difference Vreg2. It is the result of being designed to. In order to make the inner peripheral side maximum potential difference VO5 and the inner peripheral side maximum potential difference VI4 exactly match, it is possible by adjusting 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 of the present embodiment, the inner peripheral side maximum potential difference VO5 and the inner peripheral side maximum potential difference VI4 are substantially equalized, so that the outer fourth electrode 74 is as described in FIG. 4 (A). There is an advantage that a uniform electrostatic attraction can be generated in almost the entire circumference (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 have a total of N = 9 steps. , The first gap G1 between 50 is variable. At this time, the minimum value of the amount of voltage change between each applied voltage applied to the same segment electrode 62 (or 64) among the K = 2 first and second electrodes 62 and 64 is defined as ΔVkmin. In the examples 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 has low sensitivity to noise.

1.2.6 Comparative Example In the comparative example, as shown in FIGS. 14 (A) and 14 (B), the lower electrode 61 shown in FIG. 14 (A) is used in place of the lower electrode 60 of the present embodiment. The upper electrode 71 shown in FIG. 14B is used instead of the upper electrode 70. 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 tunable wavelength data obtained thereby. Data numbers 1 to 9 in FIG. 15 are the same as data numbers 1 to 9 in FIGS. 7 and 11. 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 shown in FIG. 15 and the transmission peak wavelength.

Also in FIG. 15, in order to change the transmission peak wavelength in nine steps from the maximum transmission peak wavelength λ0 = 700 nm to the minimum wavelength λ8 = 380 nm, the first gap G1 between the first and second reflection films 40 and 50 is maximum. It is variable in 9 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 9 steps from the maximum wavelength λ0 to the minimum wavelength λ8 (see also FIG. 16).

However, in the comparative example, the nine-step 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 each applied voltage in N = 9 stages when the lower electrode 61 is formed by a single electrode is defined as ΔV1 min. In the example of FIG. 15, ΔV1min = 0.9V. Considering that the power supply noise is about 0.1V, the minimum voltage change amount ΔV1min in the comparative example has high sensitivity to noise.

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

2. 2. Modification example of the optical filter FIG. 18 shows an optical filter 11 different from the optical filter 10 of FIG. The first substrate 21 shown in FIG. 18 is a first surface around the second facing surface 20A2 on which the lower electrode 60 is formed in FIG. 1 and the first facing surface 20A1 on which the first reflective film 40 is formed in a plan view. The surface 20A21 includes a second surface 20A22 arranged around the first surface 20A21 in a plan view and having a step with the first surface 20A21.

The first electrode 62 is arranged on the first surface 20A21, the second electrode 64 is arranged on the second surface 20A22, and the initial gap G22 between the second electrode 64 and the upper electrode 70 is the first electrode 62 and the above. It differs from the initial gap G21 with the top electrode 70.

The reason for making such a relationship is as follows. Of the initial gaps G21 and G22, the initial gap G22 corresponding to, for example, the second electrode 64, which is driven first, is narrowed by the electrostatic attraction acting between the second electrode 64 and the second electrode. At this time, the gap G21 is also narrowed at the same time and becomes smaller than the initial gap. Therefore, when driving the first electrode 62, the gap G21 is smaller than the initial value.

Here, it is assumed that the first surface 20A21 and the second surface 20A22 are flush with each other and the initial values of the gaps G21 and G22 are the same. In this case, for example, the gap G22 when the second electrode 64 is first driven becomes larger than the gap G21 when the first electrode 62 is driven later. Therefore, the electrostatic attraction when the second electrode 64 is first driven must be set to be excessively larger than the electrostatic attraction when the first electrode 64 is driven.

Therefore, in this case, as shown in FIG. 18, it is preferable to make the initial value of the gap G22 smaller than the initial value of the gap G21. When the first electrode 62 is driven first, the initial value of the gap G21 may be made smaller than the initial value of the gap G22.

3. 3. Analytical Instrument FIG. 19 is a block diagram showing a schematic configuration of a colorimeter, which is an example of an analytical instrument according to an embodiment of the present invention.

In FIG. 19, the colorimeter 200 includes a light source device 202, a spectroscopic measurement device 203, and a color measurement 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 the light reflected by the inspection target A, to enter the spectroscopic measurement device 203. Then, the spectroscopic measurement device 203 disperses the light to be inspected, and the spectroscopic characteristic measurement is performed to measure the amount of light of each of the separated wavelengths. 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 target A, that is, the color of which wavelength and how much 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. Further, the plurality of lenses 212 include a collimator lens, and the light source device 202 makes white light emitted from the light source 210 parallel light by the collimator lens, and heads toward the inspection target A from a projection lens (not shown). And eject.

As shown in FIG. 19, the spectroscopic measurement device 203 includes an 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 the inside at a position facing the etalon 10.

The light receiving unit 220 is composed of a plurality of photoelectric exchange elements (light receiving elements), and generates an electric signal according to the amount of light received. Then, the light receiving unit 220 is connected to the control circuit unit 240, and outputs the generated electric signal as a light receiving signal to the control circuit unit 240. The optical filter module can be configured by unitizing the etalon 10 and the light receiving unit (light receiving element) 220.

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 drive voltage may be applied so as to generate a desired potential difference between the lower electrode 60 and the upper electrode 70. For example, a predetermined voltage may be applied to the lower electrode 60 and the upper electrode 70 may be used as the ground potential. Good. It is preferable to use a DC voltage as the drive voltage.

The control circuit unit 240 controls the overall operation of the spectroscopic measurement device 203. As shown in FIG. 19, the control circuit unit 240 is composed of, for example, a CPU 250, a storage unit 260, and the like. Then, the CPU 350 executes the spectroscopic measurement process based on various programs and various data stored in the storage unit 250. The storage unit 250 is configured to include a recording medium such as a memory or a hard disk, and stores various programs, various data, and the like in a readable manner.

Here, the storage unit 260 stores the voltage adjusting unit 261, the gap measuring unit 262, the light amount recognition unit 263, and the measuring unit 264 as programs. The gap measuring unit 262 may be omitted as described above.

Further, the storage unit 260 has the voltage table data 265 shown in FIG. 7 in which the voltage values applied to the electrostatic actuators 80 and 90 for adjusting the interval of the first gap G1 and the time for applying the voltage values are associated with each other. 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 color measurement processing 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 personal digital assistant, or a computer dedicated to color measurement can be used.

Then, as shown in FIG. 19, the color measurement control device 204 includes a light source control unit 272, a spectral characteristic acquisition unit 270, a color measurement 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, for example, based on the setting input of the user, and emits white light having a predetermined brightness from the light source device 202.

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

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

FIG. 20 is a flowchart showing the spectroscopic measurement operation of the spectroscopic measurement device 203. First, the CPU 250 of the control circuit unit 240 activates the voltage adjusting unit 261, the light amount recognition unit 263, and the measuring unit 264. Further, the CPU 250 initializes the measurement variable n (sets n = 0) as an initial state (step S1). The measurement variable n takes an integer value of 0 or more.

After that, the measuring 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). The size of the first gap G1 in this initial state may be measured in advance at the time of manufacturing the spectroscopic measuring apparatus, for example, and stored in the storage unit 260. Then, the amount of transmitted light in the initial state obtained here and the size of the first gap G1 are output to the color measurement control device 204.

Next, the voltage adjusting 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 variable n (step S4).

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

Further, the measurement unit 264 performs the spectroscopic measurement process at the timing when the application time elapses (step S7). That is, the measuring unit 264 causes the light amount recognizing unit 263 to measure the amount of transmitted light. Further, the measuring unit 264 controls the colorimetric control device 204 to output the spectroscopic measurement result in which the measured amount of transmitted light and the wavelength of the transmitted light are associated with each other. In the measurement of the amount of light, the data of the amount of light of a plurality of times or all the times is stored in the storage unit 260, and after the data of the amount of light for each of a plurality of times or the data of the amount of light of all times is acquired, each light amount is collectively measured. May be measured.

After that, the CPU 250 determines whether or not the measurement variable n has reached the maximum value N (step S8), and if it determines that the measurement variable n is N, the CPU 250 ends a series of spectroscopic measurement operations. On the other hand, in step S8, when the measurement times variable n is less than N, the process returns to step S4, a process of adding "1" to the measurement times variable n is performed, and the processes of steps S5 to S8 are repeated.

4. Optical device FIG. 21 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. Wavelength Division Multiplexing (WDM) communication uses the characteristic that signals with different wavelengths do not interfere with each other, and if multiple optical signals with different wavelengths are used multiple times in one optical fiber, the optical fiber is used. It becomes possible to improve the amount of data transmission without adding a line.

In FIG. 21, the wavelength division multiplexing transmitter 300 has an optical filter 10 into which light from a light source 301 is incident, and light having a plurality of wavelengths λ0, λ1, λ2, ... Is transmitted from the optical filter 10. Transmitters 311, 312, 313 are provided for each wavelength. The optical pulse signals for a plurality of channels from the transmitters 311, 312, 313 are combined into one by the wavelength division 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. OCDM identifies channels by pattern matching of encoded optical pulse signals, because the optical pulses that make up an optical pulse signal contain optical components of different wavelengths.

Although some embodiments have been described above, those skilled in the art can easily understand that many modifications that do not substantially deviate from the novelty and effects of the present invention are possible. Therefore, all such modifications are included in the scope of the present invention. For example, a term described at least once in a specification or drawing with a different term in a broader or synonymous manner may be replaced by that different term anywhere in the specification or drawing.

10 ... optical filter, 20 ... first substrate, 20A1 ... first facing surface, 20A2 ... second facing surface, 20A21 ... first surface, 20A22 ... second surface, 30 ... second substrate, 30A ... facing surface, 40 ... 1st reflective film, 50 ... 2nd reflective film, 60 ... lower electrode, 62 ... 1st electrode, 62A ... 1st ring-shaped electrode, 62B ... 1st lead-out wiring, 64 ... 2nd electrode, 64A ... 2nd ring-shaped Electrode, 64B ... 2nd lead-out wiring, 64C ... 1st slit, 70, 70'... upper electrode, 72 ... 3rd electrode, 72A ... 3rd ring-shaped electrode, 74, 74'... 4th electrode, 74A, 74A' ... 4th ring-shaped electrode, 76A ... 3rd drawer wiring, 76B ... 4th drawer wiring, 78 ... 2nd slit, 80 ... 1st gap variable drive unit (electrostatic actuator), 90 ... 2nd gap variable drive unit ( Electrostatic actuator), 101-104 ... 1st to 4th external connection electrodes, 110 ... Potential difference control unit, 112 ... 1st electrode drive unit, 114 ... 2nd electrode drive unit, 116 ... Digital control unit, 120 ... Power supply, 200 ... Analytical instrument (colorimeter), 300 ... Optical instrument, G1 ... 1st gap, G2 ... 2nd gap, L ... Center line, ΔVseg1 ... Inner peripheral side potential difference, ΔVseg2 ... Outer peripheral side potential difference, W1, W2 ... Ring width

Claims (9)

It's an optical filter
1st board and
A second substrate facing the first substrate and
The first reflective film provided on the first substrate and
A second reflective film provided on the second substrate and facing the first reflective film, and
A first electrode provided on the first substrate and provided outside the outer periphery of the first reflective film in a plan view,
A second electrode provided on the first substrate and provided at a position farther from the first electrode with respect to the first reflective film in a plan view,
A third electrode provided on the second substrate, provided outside the outer circumference of the second reflective film in a plan view, and facing the first electrode and the second electrode,
With
The first electrode and the second electrode are electrically independent and are electrically independent.
The first electrode and the second electrode are arranged on the first surface of the first substrate.
The third electrode is arranged on the second surface of the second substrate.
The first surface and the second surface face each other ,
The distance from the second surface to the first electrode and the distance from the second surface to the second electrode are the same as each other when the voltage of the optical filter is not applied.
An optical filter that is characterized by that. In claim 1,
A potential difference between the first electrodes can be applied between the third electrode and the first electrode.
A potential difference between the second electrodes can be applied between the third electrode and the second electrode.
An optical filter characterized in that the period set for the potential difference between the second electrodes is longer than the period set for the potential difference between the first electrodes. In claim 1 or 2,
The first electrode has a first ring shape and has a first ring shape.
The second electrode is an optical filter having a second ring shape. In claim 3,
The third electrode is an optical filter having a third ring shape. In claim 3,
An optical filter characterized in that the ring width of the second electrode is larger than the ring width of the first electrode. In any one of claims 1 to 5,
The second substrate has a first portion and a second portion thinner than the film thickness of the first portion.
The second reflective film is an optical filter provided on the first portion of the second substrate. In any one of claims 1 to 6,
The first substrate has a third surface and the first surface lower than the third surface.
The first reflective film is provided on the third surface.
An optical filter characterized in that the first electrode and the second electrode are provided on the first surface . In any one of claims 1 to 7,
It has a lead-out wiring provided on the first substrate and connected to the first electrode.
An optical filter characterized in that the lead-out wiring is provided so as to extend away from the first reflective film and does not overlap with the second electrode in a plan view from the thickness direction of the first substrate. An analytical instrument including the optical filter according to any one of claims 1 to 8.

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