JP2019015865A - Wavelength variable interference filter, optical device, electronic apparatus, and method for manufacturing wavelength variable interference filter - Google Patents

Abstract

To provide a wavelength variable interference filter that can be miniaturized, an optical device, an electronic apparatus, and a method for manufacturing a wavelength variable interference filter.SOLUTION: A wavelength variable interference filter comprises: a first mirror; and a substrate that is provided with a second mirror opposed to the first mirror and has a first surface opposed to the first mirror and a second surface on the opposite side of the first surface. At least any one of the first surface and second surface of the substrate is provided with a first concave part that has a bottom part and a curved part curved from the outer periphery of the bottom part toward the outer periphery of the substrate. In plan view seen from the thickness direction of the substrate, the bottom part includes a mirror area overlapping the first mirror and the second mirror and a diaphragm area arranged on the outer periphery of the mirror area.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a wavelength tunable interference filter, an optical device, an electronic apparatus, and a method for manufacturing a wavelength tunable interference filter.

Conventionally, a variable wavelength interference filter having a pair of mirrors arranged opposite to each other and capable of changing the dimension between the mirrors is known (for example, see Patent Document 1).
In the wavelength tunable interference filter described in Patent Document 1, a first substrate on which a first reflective film (first mirror) is provided and a second substrate on which a second reflective film (second mirror) is provided are joined, The one reflection film and the second reflection film are arranged to face each other with a gap. The second substrate includes a movable part on which the second reflective film is provided, and a holding part (diaphragm) formed so as to surround the outer periphery of the movable part. An electrostatic actuator is constituted by the first electrode provided on the first substrate and the second electrode provided on the second substrate and facing the first electrode. When a drive voltage is applied to the electrostatic actuator, The holding portion is bent by the electric attractive force, and the movable portion is displaced toward the first substrate.

JP2013-178392A

  By the way, in the wavelength variable interference filter as described in Patent Document 1, the holding portion which is a diaphragm is formed by using wet etching (isotropic etching). In such wet etching, the second substrate can be etched to a desired depth at a high etching rate.

  However, since wet etching is isotropic etching, the side surface continuous with the bottom surface of the groove is an arc-shaped curved surface. In the configuration as described in Patent Document 1, since the holding portion formed by wet etching is provided so as to surround the movable portion, the side surface between the bottom surface (diaphragm portion) of the holding portion and the movable portion is the first curve. The side surface between the diaphragm portion and the substrate outer peripheral portion becomes the second curved surface. In addition, in a plan view of the wavelength tunable interference filter as viewed from the thickness direction (opposite direction of the pair of reflection films), the width dimensions of these curved surfaces are substantially the same as the etching depth. Here, in Patent Document 1, a movable portion, two first curved surfaces, two diaphragm portions, a second curved surface, and two substrate outer peripheral portions are provided along the radial direction of the movable portion in the plan view. It is done. That is, four curved surfaces are provided, and it is necessary to set the plane dimension in consideration of the width dimension, and there is a problem that the plane dimension of the wavelength variable interference filter becomes large.

  An object of the present invention is to provide a tunable interference filter, an optical device, an electronic apparatus, and a method for manufacturing the tunable interference filter that can be miniaturized.

  A wavelength tunable interference filter according to an application example of the invention includes a first mirror and a second mirror that faces the first mirror, and is opposite to the first surface and the first surface that face the first mirror. A substrate having a second surface on the side, and at least one of the first surface and the second surface of the substrate has a bottom and a curve that curves from the outer periphery of the bottom portion toward the outer periphery of the substrate A first concave portion having a first portion is provided, and the bottom portion is disposed in a mirror region overlapping with the first mirror and the second mirror and an outer periphery of the mirror region in a plan view as viewed from the thickness direction of the substrate. It includes a diaphragm region.

  In this application example, a mirror region and a diaphragm region are provided at the bottom of the first recess formed in the substrate. In other words, the wavelength tunable interference filter of this application example has a configuration in which the mirror region and the diaphragm region are included in one bottom portion, and from the second surface to the bottom portion between the mirror region and the diaphragm region as in the past. The planar dimension of the wavelength tunable interference filter can be reduced compared to a configuration in which a curved surface having a width dimension substantially the same as the depth dimension is provided.

  In the wavelength tunable interference filter according to this application example, the substrate protrudes from the first surface toward the first mirror in the mirror region at the bottom, and a protruding portion whose protruding tip is a flat surface facing the first mirror It is preferable that the second mirror is provided on a flat surface of the protruding portion facing the first mirror.

  In this application example, the bottom mirror region is provided with a protrusion that protrudes from the first surface toward the first mirror, and a second mirror is provided at the protrusion tip of the protrusion. In such a configuration, the thickness dimension (dimension in the substrate thickness direction) of the mirror area where the protrusion is provided in the bottom is larger than the thickness dimension in the diaphragm area where the protrusion is not provided. Thereby, a mirror area | region becomes difficult to bend than a diaphragm area | region, and the deformation | transformation of a diaphragm area | region can suppress the bending of a 2nd mirror at the time of changing the distance between a 1st mirror and a 2nd mirror.

  In the wavelength tunable interference filter according to this application example, the first surface of the substrate has an area in the plan view in a region other than the mirror region in a region overlapping the first recess in the plan view. It is preferable that the 2nd recessed part smaller than a recessed part is provided.

In this application example, on the first surface of the substrate facing the first mirror, a second recess having a smaller planar dimension than the first recess is provided in a region other than the mirror region in the first recess. The region other than the mirror region in the first recess may be both the diaphragm region and the curved portion in the bottom portion, or may be only the diaphragm region or only the curved portion region.
In such a configuration, the second recess makes it possible for the region other than the mirror region to bend more easily than the mirror region, thereby suppressing the bending of the mirror region.

  In the wavelength tunable interference filter according to this application example, the counter substrate facing the first surface of the substrate, the first electrode provided on the counter substrate, and the first surface of the substrate, in the plan view, It is preferable to include a second electrode provided in a region other than the mirror region in the region overlapping the first recess and overlapping the first electrode.

In this application example, the counter substrate is provided to face the first surface of the substrate where the second recess is provided, and the first electrode provided on the counter substrate and the second electrode provided on the substrate face each other. In such a configuration, the first electrode and the second electrode constitute an electrostatic actuator, and by applying a voltage to the electrostatic actuator, the substrate can be bent with an electrostatic attractive force corresponding to the voltage. That is, the second mirror can be displaced in a direction to increase or decrease the dimension between the first mirror and the second mirror (hereinafter referred to as a mirror gap).
Here, in this application example, the second electrode is formed in a region where the second concave portion of the first surface is provided. That is, the second electrode is provided along the concave surface of the second recess. Therefore, the surface area of the second electrode increases and the charge that can be held increases as compared with the case where the second electrode is provided on a plane. Therefore, the electric power for driving the electrostatic actuator by a predetermined amount can be reduced, and the power saving can be promoted.

Further, in the wavelength tunable interference filter according to this application example, a configuration in which a third recess having a smaller area in the plan view than the first recess is provided on a surface of the substrate other than the mirror region of the first recess. It is good.
In this application example, a third concave portion having an area smaller than that of the first concave portion is provided on the concave inner peripheral surface of the first concave portion, that is, a surface opposite to the first surface of the first concave portion. In such a configuration, the diaphragm region can be more easily bent than in the case where the second recess is provided on the first surface.

An optical device according to an application example of the invention includes the wavelength variable interference filter as described above and a housing that houses the wavelength variable interference filter.
In this application example, the planar dimension of the wavelength variable interference filter can be reduced as compared with the conventional example, as in the above application example. For this reason, the housing | casing which accommodates the said wavelength variable interference filter can also be reduced in size, and size reduction of an optical device can be accelerated | stimulated.

An electronic apparatus according to an application example of the invention includes the above-described wavelength tunable interference filter and a control unit that controls driving of the wavelength tunable interference filter.
In this application example, the planar dimension of the wavelength variable interference filter can be reduced as compared with the conventional example, as in the above application example. For this reason, it is also possible to reduce the size of an electronic device including the variable wavelength interference filter. In addition, since the substrate can be reduced in weight, the driving voltage when driving the variable wavelength interference filter can be reduced, and power saving in the electronic apparatus can be achieved. Furthermore, in an electronic device in which a wavelength variable interference filter is mounted on a carriage and the carriage is driven by a driving force such as a motor, the power required for driving the carriage can be reduced.

  A method of manufacturing a wavelength tunable interference filter according to an application example of the present invention includes: a first mirror; a second mirror facing the first mirror; a first surface facing the first mirror; A substrate having a second surface opposite to the surface, and a method for manufacturing the wavelength tunable interference filter, wherein at least one of the first surface and the second surface of the substrate is wet-etched to form a bottom portion And a recessed portion forming step for forming a first recessed portion having a curved portion that curves from the outer periphery of the bottom portion toward the outer periphery of the substrate, and a position overlapping the first mirror in a plan view as viewed from the thickness direction of the substrate. And a second mirror forming step for forming the second mirror.

In this application example, a first concave portion having a bottom portion and a curved portion is formed on the second surface side of the substrate in the concave portion forming step, and a second mirror is formed in the bottom portion of the first concave portion in the second mirror forming step. .
In this case, a mirror region that overlaps the first mirror and the second mirror and a diaphragm region for displacing the second mirror toward the first mirror are formed in the bottom of the first recess, and the mirror region and the diaphragm region A curved surface is not formed in between. Therefore, a variable wavelength interference filter having a small planar dimension can be manufactured.

The top view which shows schematic structure of the wavelength variable interference filter in 1st embodiment. Sectional drawing which shows schematic structure of the wavelength variable interference filter in 1st embodiment. The expanded sectional view of the diaphragm area | region in 1st embodiment. The figure which compares the planar dimension of the wavelength variable interference filter of 1st embodiment, and the conventional wavelength variable interference filter. The flowchart which shows the manufacturing method of the wavelength variable interference filter of 1st embodiment. Schematic which shows each step which forms the 1st board | substrate in the manufacturing method of the wavelength variable interference filter of 1st embodiment. Schematic which shows each step which forms the 2nd board | substrate in the manufacturing method of the wavelength variable interference filter of 1st embodiment. Sectional drawing which shows schematic structure of the wavelength variable interference filter in 2nd embodiment. The figure which shows typically the force which acts on a 2nd recessed part in the diaphragm area | region in 1st embodiment. The figure which shows typically the force which acts on a 3rd recessed part in the diaphragm area | region in 2nd embodiment. Sectional drawing which shows schematic structure of the optical device in 3rd embodiment. The whole perspective view showing the schematic structure of the electronic equipment (printer) in a fourth embodiment. The block diagram which shows schematic structure of the electronic device in 4th embodiment. Sectional drawing which shows schematic structure of the carriage of the electronic device in 4th embodiment. FIG. 6 is a cross-sectional view illustrating a schematic configuration of a variable wavelength interference filter according to Modification 1; Sectional drawing which shows schematic structure of the wavelength variable interference filter which concerns on the modification 2. FIG. FIG. 10 is a cross-sectional view showing another example of a wavelength tunable interference filter according to Modification 2. Sectional drawing which shows schematic structure of the wavelength variable interference filter in the modification 3. FIG.

[First embodiment]
Hereinafter, the variable wavelength interference filter according to the first embodiment will be described.
FIG. 1 is a plan view showing a schematic configuration of a variable wavelength interference filter 5 of the first embodiment. FIG. 2 is a cross-sectional view showing a schematic configuration of the variable wavelength interference filter 5 obtained by cutting FIG. 2 along the line AA.
The variable wavelength interference filter 5 includes a first substrate 51 and a second substrate 52 as shown in FIGS. 1 and 2. The first substrate 51 and the second substrate 52 are integrally formed by bonding with a bonding film 53 such as a plasma polymerization film mainly containing siloxane.
The first substrate 51 is provided with a first mirror 54, and the second substrate 52 is provided with a second mirror 55, and the first mirror 54 and the second mirror 55 are opposed to each other through a mirror gap G. Has been placed. The wavelength variable interference filter 5 includes an electrostatic actuator 56 that changes the size of the mirror gap G.
Hereinafter, the configuration of each unit will be described in detail.

(Configuration of the first substrate)
The first substrate 51 corresponds to the counter substrate of the present invention in the first embodiment. As shown in FIG. 2, the first substrate 51 includes an electrode arrangement groove 511 and a mirror installation portion 512 formed on the surface facing the second substrate 52 by, for example, etching. For example, the first substrate 51 is formed to have a thickness larger than that of the second substrate 52, and the first substrate 51 when the electrostatic attractive force is applied by the electrostatic actuator 56 is suppressed.
Further, one end side (for example, side C5-C6 in FIG. 1) of the first substrate 51 protrudes from one end side (side C1-C2) of the second substrate 52, and the wavelength variable interference filter 5 is, for example, a package housing or It can be used as a fixing part when fixing to a base or the like.

  The electrode arrangement groove 511 is formed in a substantially annular shape centered on a predetermined filter center axis O in a plan view (hereinafter simply referred to as a plan view) when the first substrate 51 is viewed from the substrate thickness direction. Although not shown, a lead groove having the same depth as the electrode arrangement groove 511 is extended from the electrode arrangement groove 511 toward the side C <b> 3-C <b> 4 on the first substrate 51.

A first electrode 561 constituting the electrostatic actuator 56 is disposed on the groove bottom surface of the electrode arrangement groove 511.
The first electrode 561 is provided in a region facing the second electrode 562 described later on the groove bottom surface of the electrode arrangement groove 511. For example, the first electrode 561 is formed in a substantially annular shape along the electrode arrangement groove.
The first electrode 561 is connected to a first extraction electrode 563 (see FIG. 1) extending to the side C3-C4 along the extraction groove. The first extraction electrode 563 is connected to a first connection electrode 565 provided on the second substrate 52 side in the extraction groove.
In the present embodiment, a configuration in which one first electrode 561 is provided is shown. However, for example, a configuration in which two or more electrodes that are concentric circles around the filter center axis O may be provided. Moreover, as a shape of the 1st electrode 561, it is good also as a structure by which the notch part which connects the inside and outside of a ring is provided in part, for example. In this case, another electrode (for example, an electrode connected to the first mirror 54) independent of the first electrode 561 can be provided through the notch.

The mirror installation portion 512 is provided inside the electrode placement groove 511 (on the filter center axis O side) in a plan view, and is formed so as to protrude toward the second substrate 52 as shown in FIG. The protruding tip surface of the mirror installation portion 512 is a flat surface, and the first mirror 54 is provided on the protruding tip surface.
For the first mirror 54, for example, a metal film such as Ag, an alloy film such as an Ag alloy, a dielectric multilayer film in which a high refractive layer (for example, TiO ₂₎ and a low refractive layer (for example, SiO ₂₎ are stacked, or the like is used. it can.

  In addition, the first bonding portion 513 is provided on the surface of the first substrate 51 facing the second substrate 52 where the electrode placement groove 511, the mirror installation portion 512, and the extraction groove are not formed. The first bonding portion 513 is bonded to the second substrate 52 via the bonding film 53.

  In the present embodiment, an example is shown in which the mirror placement portion 512 is positioned closer to the second substrate 52 than the electrode placement groove 511. For example, depending on the wavelength range of light transmitted through the wavelength variable interference filter 5, the electrode placement The groove 511 may be positioned on the second substrate 52 side with respect to the mirror installation portion 512. That is, a recess may be formed inside the electrode arrangement groove 511 in the plan view (on the filter center axis O side), and the first mirror 54 may be provided on the bottom surface of the recess.

(Configuration of second substrate)
The second substrate 52 corresponds to the substrate of the present invention. In the second substrate 52, one end side (side C <b> 3-C <b> 4 side) of the second substrate 52 protrudes outside the sides C <b> 7-C <b> 8 of the first substrate 51, and configures the electrical component 560. A second mirror 55 and a second electrode 562 are provided on the surface (first surface 521) of the second substrate 52 facing the first substrate 51.
A surface of the second substrate 52 opposite to the first substrate 51 (second surface 522) is provided with a first recess 523 that is concave on the first substrate 51 side. A substrate outer peripheral portion 524 is provided on the outer side of 523.

The first recess 523 is formed by performing wet etching on the second surface 522 of the second substrate 52, and is a recess that is substantially circular in plan view. The first recess 523 includes a bottom portion 525 having a predetermined diameter centered on the filter center axis O, and a curved portion 526 provided outside the bottom portion 525 and continuing to the substrate outer peripheral portion 524.
Here, in a plan view as shown in FIG. 1, a region of the bottom 525 that overlaps the first mirror 54 is referred to as a mirror region Am, and a region from the outer peripheral edge of the mirror region Am to the curved portion 526 is referred to as a diaphragm region Ad. Called.

In the present embodiment, of the surface of the first recess 523 opposite to the first substrate 51, the bottom surface overlapping the bottom 525 is in a state where no voltage is applied to the electrostatic actuator 56, and from the mirror region Am to the diaphragm region. It becomes a flat plane over Ad. That is, in the present embodiment, the mirror area Am and the diaphragm area Ad are adjacent to each other in plan view.
Of the surface of the first recess 523 opposite to the first substrate 51, the surface overlapping the curved portion 526 is the surface opposite to the first substrate 51 in the substrate outer peripheral portion 524 from the outer peripheral edge of the bottom surface 525A ( The second surface 522) is a continuous arcuate curved surface.

  The first surface 521 of the second substrate 52 has a protrusion 527 that protrudes closer to the first substrate 51 than the first surface 521 at a position overlapping the mirror region Am in plan view. The protruding portion 527 is formed, for example, by performing dry etching on a region other than the protruding portion 527 of one surface of the base material for forming the second substrate 52 that faces the first substrate 51. The protruding tip surface of the protruding portion 527 is parallel to the protruding tip surface of the mirror installation portion 512 of the first substrate 51, and the second mirror 55 is provided on the protruding tip surface of the protruding portion 527.

The projecting dimension of the projecting part 527 from the first surface 521 is 2 to 3 times the thickness dimension of the diaphragm region Ad in the bottom part 525. At the bottom 525, the thickness dimension of the mirror area Am is about 3 to 4 times the thickness dimension of the diaphragm area Ad. In this case, the inconvenience that the mirror region Am is bent due to the stress when the diaphragm region Ad is bent toward the first substrate 51 can be suppressed, and the bending of the second mirror 55 can be suppressed.
Further, the projecting dimension of the projecting part 527 is smaller than the depth dimension of the first recessed part 523 (the distance from the second surface 522 to the bottom surface 525A). For example, for the second substrate 52 having a substrate thickness dimension of 500 μm, the first recess 523 is formed with a depth dimension of, for example, 350 μm, whereas the depth dimension of dry etching when forming the protrusion 527 is For example, it becomes 100 μm. In this case, with respect to the diaphragm area Ad having a thickness of 50 μm, the protrusion dimension of the protrusion 527 is 100 μm, and the thickness dimension of the mirror area Am is 150 μm.

In the present embodiment, when the dry etching is performed on the base material of the second substrate 52, the first surface 521 is constituted by the etched portion. Of the first surface 521, a surface other than a portion where a second recess 528 described later is provided is a flat plane in a state where no voltage is applied to the electrostatic actuator 56.
The first surface 521 is provided from the substrate outer peripheral portion 524 to the curved portion 526 and the diaphragm region Ad. A portion of the first surface 521 that overlaps the substrate outer peripheral portion 524 and that opposes the first bonding portion 513 of the first substrate 51 constitutes the second bonding portion 524A, and the second surface 521A is interposed between the first film 521 and the bonding film 53. Bonded to the first bonding portion 513 of one substrate 51.

In the above example, the protrusion 527 is formed by performing dry etching on the surface of the second substrate 52 facing the first substrate 51 of the base material. In this case, since anisotropic etching is performed, the boundary between the side surface of the protruding portion 527 and the first surface 521 is a corner portion that intersects at a substantially right angle. Therefore, the mirror area Am and the diaphragm area Ad can be disposed so as to be substantially adjacent to each other. However, when the diaphragm region Ad is bent toward the first substrate 51 side, a stress may concentrate on the corner portion, which may cause a crack.
Therefore, the protruding portion 527 may be formed by performing wet etching on the surface of the base material of the second substrate 52 that faces the first substrate 51. In this case, an arcuate curved surface is formed from the projecting tip surface of the projecting portion 527 to the first surface 521, and the occurrence of cracks as described above can be suppressed.

The 2nd mirror 55 is provided in the protrusion front end surface of the protrusion part 527 as mentioned above. Since the protruding tip surface is a plane parallel to the protruding tip surface of the mirror installation portion 512 where the first mirror 54 is provided, the first mirror 54 and the second mirror 55 are also parallel.
As the second mirror 55, a reflective film having the same configuration as that of the first mirror 54 described above can be used.

FIG. 3 is an enlarged cross-sectional view of a part of the diaphragm region Ad of the first recess 523.
In the present embodiment, on the first surface 521 of the second substrate 52, as shown in FIG. 3, a plurality of second recesses 528 (micro diaphragms) are provided in a matrix, for example. Specifically, the second recess 528 is provided in an area of the first surface 521 that overlaps the first recess 523 and in an area other than the mirror area Am.
In the present embodiment, an example is shown in which the second recess 528 is provided in a region overlapping the diaphragm region Ad and the bending portion 526. However, the second recess 528 may be provided only in a region overlapping the diaphragm region Ad. A structure provided only in a region overlapping with 526 may be employed.

The second recess 528 is a substantially hemispherical recess, and the diameter in plan view is sufficiently smaller than the diameter of the first recess 523. Moreover, the depth dimension (radius dimension) of the 2nd recessed part 528 is smaller than the thickness dimension (dimension in alignment with the normal line direction of the 2nd mirror 55) of the bottom part 525 of the 1st recessed part 523, as shown in FIG.
By providing such a second recess 528, the thickness dimension of the second recess 528 is reduced, so that the diaphragm region Ad is easily bent toward the first substrate 51 side.

The first surface 521 of the second substrate 52 is provided with a substantially annular second electrode 562 facing the first electrode 561 in a region other than the mirror region Am and at least overlapping with the diaphragm region Ad. ing.
In the present embodiment, the second electrode 562 is provided from the diaphragm region Ad of the bottom portion 525 to the curved portion 526. Further, the second electrode 562 is formed along the concave inner peripheral surface of the second concave portion 528 at a portion overlapping the second concave portion 528. That is, the portion of the second electrode 562 that overlaps the second concave portion 528 has a concave shape (substantially hemispherical shape) that is substantially the same shape as the concave curved surface of the second concave portion 528.

Here, an example is shown in which the second electrode 562 is provided from a region overlapping the diaphragm region Ad to a region overlapping the bending portion 526. For example, the second electrode 562 is provided only in a region overlapping the diaphragm region Ad. It is good also as a structure.
Further, as the second electrode 562, as in the first electrode 561, for example, a configuration in which two or more electrodes having a concentric circle centered on the filter central axis O may be provided. It is good also as a structure by which the notch part to be provided is provided.

The second substrate 52 is provided with a second extraction electrode 564 (see FIG. 1) extending from the outer peripheral edge of the second electrode 562 to the electrical component 560 through a region facing the extraction groove of the first substrate 51. I have.
Furthermore, the second substrate 52 includes a first connection electrode 565 provided from the region facing the lead groove of the first substrate 51 to the electrical component 560. The first connection electrode 565 is connected to the first extraction electrode 563 provided in the extraction groove of the first substrate 51 via, for example, a bump electrode.

In the wavelength variable interference filter 5 as described above, the second extraction electrode 564 and the first connection electrode 565 are connected to a control circuit (driver circuit) that controls the wavelength variable interference filter 5, and the control circuit performs electrostatic The voltage applied between the first electrode 561 and the second electrode 562 constituting the actuator 56 is controlled. Thereby, electrostatic attraction acts between the first electrode 561 and the second electrode 562, and the diaphragm region Ad of the first recess 523 is displaced toward the first substrate 51, thereby changing the dimension of the mirror gap G. Is possible.
At this time, the second electrode 562 is formed along the concave inner peripheral surfaces of the first surface 521 and the second concave portion 528. In such a configuration, the surface area of the second electrode 562 can be increased compared to the case where a flat second electrode is formed along the first surface 521, and the first voltage when a predetermined voltage is applied to the electrostatic actuator 56 can be increased. The amount of charge held by the two electrodes 562 also increases. Therefore, the electrostatic attractive force generated when a predetermined voltage is applied to the electrostatic actuator 56 also increases.

[Plane dimensions of tunable interference filter]
Next, the dimension (plane dimension) in the direction orthogonal to the substrate thickness direction of the wavelength variable interference filter 5 of the present embodiment as described above will be described.
FIG. 4 is a diagram comparing the dimensions of the conventional tunable interference filter 5f and the tunable interference filter 5 of the present embodiment. In FIG. 4, only a part of the second substrate 52 is displayed for simplification of description.
In FIG. 4, the upper part shows the second substrate 52f of the conventional variable wavelength interference filter 5f. In the conventional wavelength tunable interference filter 5f, the second substrate 52f includes a movable portion 520f centered on the filter center axis O, and an annular recess 523f is formed around the movable portion 520f. A mirror region Am is provided in the movable portion 520f, and a bottom portion 525f of the recess 523f constitutes a diaphragm region Ad. In such a configuration, the curved portion 526f having an arc surface is provided between the bottom portion 525f of the recess 523f and the movable portion 520f and between the bottom portion 525f and the substrate outer peripheral portion 524f.
For this reason, the dimension L1 (planar dimension) in the direction orthogonal to the substrate thickness direction of the wavelength variable interference filter 5f is at least the dimension Lm of the mirror region Am, the size Ld of the two diaphragm regions Ad, and the outer circumferences of the two substrates. and dimensions Lo parts 524f, 4 one minute which is the sum of the dimensions _{L R} of the curved portion 526F (i.e., L1 = Lm + 2Ld + 2Lo + 4L R) only is required.

4 shows the second substrate 52 of the wavelength tunable interference filter 5 of the present embodiment. As shown in FIG. 4, the wavelength tunable interference filter 5 has a mirror area Am, a diaphragm area Ad, and a substrate outer peripheral portion 524 having the same dimensions as those of the conventional wavelength tunable interference filter 5f, but the mirror area Am and the diaphragm area Ad are separated from each other. The bending portion 526 is not provided therebetween. Thus, in this embodiment, dimension L2 which is perpendicular to the substrate thickness direction of the variable wavelength interference filter 5, L2 = Lm + 2Ld + 2Lo + 2L R , and the only dimension corresponding to the two curved portions 526 (2L _R), conventional tunable It becomes smaller than the interference filter 5f.

The lower part of FIG. 4 shows the variable wavelength interference filter 5A in the case where the protrusion 527 is formed by wet etching. When the protruding portion 527 is formed by wet etching, a curved surface is formed between the protruding portion 527 and the first surface 521, and a curved portion 526A is also formed between the mirror region Am and the diaphragm region Ad.
However, as described above, the protrusion dimension of the protrusion 527 (etching depth during wet etching) is smaller than the depth dimension of the first recess 523. Therefore, as shown in the lower part of FIG. 4, the curved portion width of 526A _{L R2} is reduced sufficiently in comparison with the width _{L R} of the curved portion 526f between the conventional mirror area Am _f and the diaphragm region Ad _f . For this reason, even in this case, the planar dimension of the wavelength tunable interference filter 5A is smaller than that of the conventional wavelength tunable interference filter 5f.

[Method for Manufacturing Wavelength Variable Interference Filter 5]
Next, a manufacturing method of the wavelength variable interference filter 5 as described above will be described.
FIG. 5 is a flowchart in the manufacturing method of the wavelength variable interference filter 5 in the present embodiment.
In the manufacture of the variable wavelength interference filter 5, as shown in FIG. 5, the first substrate forming step S1, the first electrode forming step S2, the first mirror forming step S3, the second substrate forming step S4, and the second electrode forming step S5. The second mirror forming step S6 and the joining step S7. In addition, although the example which implements 2nd board | substrate formation step S4-2nd mirror formation step S6 after 1st board | substrate formation step S1-1st mirror formation step S3 is shown, for example, 2nd board | substrate formation step S4-2nd After the mirror forming step S6, the first substrate forming step S1 to the first mirror forming step S3 may be performed.

FIG. 6 is a diagram schematically showing the first substrate 51 (first glass substrate M1) in each step from the first substrate forming step S1 to the first mirror forming step S3.
Here, an example in which glass substrates are used as the first substrate 51 and the second substrate 52 will be described.

(First substrate formation step)
In the first substrate forming step S1, a resist R1 is formed on the surface of the first glass substrate M1 which is a base material of the first substrate 51, and the resist R1 is patterned by a photolithography method to form the electrode placement groove 511 and the lead-out. The bottom surface of the groove and the formation area of the mirror installation part 512 are opened. Thereafter, as shown first in FIG. 6, wet etching is performed to dig up one surface of the first glass substrate M <b> 1 to the depth of the protruding tip surface of the mirror installation portion 512. In wet etching on a glass substrate, for example, buffered hydrofluoric acid (for example, a mixed aqueous solution of NH ₄ HF ₂ (20.2 wt%) and NH ₄ F (21.2 wt%)) is used as an etching solution. When a concave groove having an arithmetic average roughness Ra of less than 1 nm is formed on a glass substrate by etching, for example, the temperature during the etching process is set to 30 degrees, for example, an etching process of about 10 minutes and a drying process. Repeat several times alternately.

  Thereafter, a resist R2 that covers the mirror installation portion 512 is formed. For example, after removing the resist R1, a resist R2 is formed on the surface of the first glass substrate M1, and the bottom surface of the electrode placement groove 511 is opened by patterning using a photolithography method. Thereafter, wet etching using, for example, buffered hydrofluoric acid is performed, and one surface of the first glass substrate M1 is dug down to the depth of the bottom surface of the electrode placement groove 511 as shown in the second part of FIG. Thereafter, the resist R2 is removed.

(First electrode formation step)
Next, a first electrode formation step S2 is performed to form a first electrode 561 and a first extraction electrode 563 (not shown in FIG. 6) as shown in the third part of FIG. In the first electrode formation step S2, a bump electrode for connecting the first extraction electrode 563 and the first connection electrode 565 is formed.
Specifically, a bump portion (not shown) that rises from the bottom surface of the extraction groove toward the second substrate 52 side at a part of the extraction groove where the first extraction electrode 563 and the first connection electrode 565 are connected. Form. As this bump part, for example, after forming a forming material such as a Ti thin film, an area other than the bump part may be removed by etching. For example, the bump part is formed when the first substrate forming step S1 is performed. You may keep it. Thereafter, the first electrode 561 and the first extraction electrode 563 are formed, and at this time, the first extraction electrode 563 is formed up to the upper surface of the bump portion.

In the formation of the first electrode 561 and the first extraction electrode 563, for example, an electrode material is formed on the first glass substrate M1 using a vapor deposition method, a sputtering method, or the like. As this electrode material, for example, a laminate of an ITO film, a TiW film and an Au film, a laminate of a Cr film and an Au film, or the like can be used. In addition, the material of the first substrate 51 (glass in the present embodiment) Various film materials having good adhesion and conductivity can be used.
Then, for example, by forming a resist pattern in which the formation positions of the first electrode 561 and the first extraction electrode 563 are opened on the first glass substrate M1, and performing wet etching, the first electrode 561 and the first extraction electrode are performed. An electrode 563 is formed.

(First mirror formation step)
In the first mirror forming step S3, the first mirror 54 is formed as shown in the fourth part of FIG. In this first mirror formation step S3, for example, the first mirror 54 is formed on the first glass substrate M1 by a sputtering method or the like, a resist pattern in which the formation position of the first mirror 54 is opened is formed, and wet etching is performed. To do. A protective film may be further formed on the first mirror 54.
Thus, the first substrate 51 is formed.

(Second substrate formation step)
FIG. 7 is a diagram showing an outline of the second substrate 52 (second glass substrate M2) in each step from the second substrate forming step S4 to the second mirror forming step S6.
The second substrate forming step S4 corresponds to the recess forming step of the present invention. In the present embodiment, it is assumed that the substrate surface of the second glass substrate M2 is surface-treated in advance so that, for example, the arithmetic average roughness Ra is less than 1 nm. In this case, a part of the second glass substrate M2 can be the second surface 522 and the protruding tip surface of the protruding portion 527.
In the second substrate forming step S4, first, a resist R3 is formed on the surface of the second glass substrate M2 which is a base material of the second substrate 52, and one surface (first surface) of the second glass substrate M2 is formed by photolithography. The resist R3 is patterned so that a portion corresponding to the bottom portion 525 of the first recess 523 is opened on the upper surface M22) corresponding to the second surface 522.

  Thereafter, wet etching is performed to dig up the upper surface M22 of the second glass substrate M2 to a predetermined depth, thereby forming a first recess 523. In this wet etching, for example, an etching process using buffered hydrofluoric acid as an etchant can be exemplified. In such wet etching, one surface of the second glass substrate M2 is dug down uniformly in the opening portion of the resist R3 according to the etching time. In wet etching, the etching solution also enters the lower portion of the resist, and etching proceeds (so-called side etching). Therefore, as shown first in FIG. 7, the first concave portion 523 includes a bottom portion 525 having a flat bottom surface facing the inside of the concave portion, and a curved portion having an arc surface continuous from the bottom surface to the second surface 522. 526.

Next, a resist R4 that covers the position where the protruding portion 527 is formed on the lower surface M21 opposite to the upper surface M22 of the second glass substrate M2 is formed by, for example, photolithography.
Thereafter, dry etching is performed on the lower surface M21 of the second glass substrate M2, and the lower surface M21 is dug down by the protruding dimension of the protruding portion 527. In this dry etching, for example, the lower surface M21 in a range where the resist R4 is not formed is etched by RIE (Reactive Ion Etching) using an ICP (Inductive Coupled Plasma) etching apparatus. At this time, as described above, the etching depth is controlled so that the thickness dimension of the mirror area Am is 3 to 4 times the thickness dimension of the diaphragm area Ad. As a result, as shown in the second part of FIG. 7, the protruding portion 527 and the first surface 521 are formed.

  Thereafter, after removing the resist R4, a resist R5 is formed on the surface of the second glass substrate M2. Further, the resist R5 is patterned so that the formation position of the second recess 528 is opened in a region of the first surface 521 that overlaps the diaphragm region Ad and the curved portion 526. Then, by performing wet etching using, for example, buffered hydrofluoric acid on the second glass substrate M2, a second recess 528 is formed as shown in the third part of FIG.

(Second electrode formation step)
In the second electrode formation step S5, as shown in the fourth part of FIG. 7, the second electrode 562, the second extraction electrode 564, and the first connection electrode 565 are formed.
In the second electrode formation step S5, as in the first electrode formation step S2, for example, the electrode material is uniformly applied to the first surface 521 formed on the second glass substrate M2 by using a vapor deposition method, a sputtering method, or the like. Form a film. Thereby, an electrode material is formed along the concave inner peripheral surface with respect to the second concave portion 528. That is, the electrode material is deposited on the second recess 528 so that the surface shape is concave. As the electrode material, for example, a laminated body of an ITO film, a TiW film and an Au film, a laminated body of a Cr film and an Au film, or the like can be used as in the first electrode 561. Then, the second electrode 562, the second extraction electrode 564, and the first connection electrode 565 are formed on the second glass substrate M2 with a resist pattern having openings, and wet etching is performed, whereby the second electrode 562, a second extraction electrode 564, and a first connection electrode 565 are formed.

(Second mirror forming step)
In the second mirror forming step S6, the second mirror 55 is formed as shown in the fifth part of FIG. In this second mirror forming step S6, as in the first mirror forming step S3, a resist pattern in which the second mirror 55 is formed on the second glass substrate M2 by, for example, a sputtering method, and the second mirror 55 is formed at an opening position. And wet etching is performed. A protective film may be further formed on the second mirror 55.
Thus, the second substrate 52 is formed.

(Joining step)
After the above, the joining step S7 is performed. In the bonding step S7, the bonding film 53 is formed on the first bonding portion 513 of the first substrate 51 and the second bonding portion 524A of the second substrate 52. As the bonding film 53, for example, a plasma polymerization film containing polyorganosiloxane as a main component can be used. In this case, for example, the surface of the bonding film 53 (plasma polymer film) is subjected to O ₂ plasma treatment or UV treatment by plasma CVD or the like to activate the surface. In the case of the O ₂ plasma treatment, for example, it is performed for 30 seconds under the conditions of an O ₂ flow rate of 1.8 × 10 ⁻³ (m ³ / h), a pressure of 27 Pa, and an RF power of 200 W. In the case of UV treatment, the treatment is performed for 3 minutes using excimer UV (wavelength 172 nm) as a UV light source. Then, alignment adjustment of the first substrate 51 and the second substrate 52 is performed, the plasma polymerization films whose surfaces are activated are overlapped, and a load of, for example, 98 (N) is applied to the joint portion for 10 minutes. Thereby, the 1st board | substrate 51 and the 2nd board | substrate 52 are joined. At this time, the first extraction electrode 563 and the first connection electrode 565 are connected by the bump portion.

  The bonding film 53 is not limited to this. For example, a metal film such as Au may be formed, and the metal films may be brought into contact with each other by applying a load, and an epoxy resin or the like may be used. The first substrate 51 and the second substrate 52 may be joined with the adhesive.

[Operational effects of the first embodiment]
In the present embodiment, in the second substrate 52 having the second mirror 55 facing the first mirror 54, the second substrate 52 has a concave shape from the second surface 522 on the opposite side to the first mirror 54 toward the first mirror 54 side. A first recess 523 is provided. The first concave portion 523 includes a bottom portion 525 and a curved portion 526 provided outside the bottom portion 525. The bottom portion 525 includes a mirror region Am overlapping the first mirror 54 and the second mirror 55, and a mirror region Am. And a diaphragm region Ad displaced to the one mirror 54 side.
In such a configuration, since a curved surface is not formed between the mirror region Am and the diaphragm region Ad, the planar size of the wavelength tunable interference filter 5 can be reduced compared to the conventional wavelength tunable interference filter 5f shown in FIG. A small tunable interference filter 5 is obtained.

In the present embodiment, the mirror region Am of the bottom 525 of the first recess 523 is provided with a protrusion 527 that protrudes from the first surface 521 toward the first mirror 54, and the protrusion tip surface of the protrusion 527 A second mirror 55 is provided.
For this reason, the mirror region Am has a thickness dimension larger than that of the diaphragm region Ad by the projecting dimension of the projecting portion 527. Therefore, the mirror area Am is less likely to bend than the diaphragm area Ad, and the bending of the second mirror 55 when the electrostatic actuator 56 is driven can be suppressed.

In the present embodiment, in the first surface 521 of the second substrate 52, a region other than the mirror region Am (in the present embodiment, the diaphragm region Ad and the curved portion 526) is overlapped with the second portion 523. A recess 528 is provided.
In such a configuration, the thickness dimension of the second recess 528 is smaller than the thickness dimension of the diaphragm area Ad where the second recess 528 is not provided and other areas of the bending portion 526. Therefore, the diaphragm region Ad is easily bent toward the first mirror 54 at the position where the second recess 528 is formed. Thereby, when the stress which pulls the 2nd mirror 55 to the 1st mirror 54 side acts, the bending of mirror area | region Am can be suppressed.

Here, the diaphragm region Ad is a region that greatly bends when the mirror gap G is changed. By providing the second recess 528 as described above, the electrostatic force when the second mirror 55 is displaced by a predetermined amount is provided. The drive voltage to the actuator 56 can be reduced, and power saving can be achieved.
Further, the bending portion 526 has a smaller deformation amount when the electrostatic actuator 56 is driven than the diaphragm region Ad. However, the bending portion 526 is provided with the second recess 528 with respect to the bending portion 526. The amount of deformation can be increased.

In the present embodiment, the second electrode 562 is formed on the first surface 521 of the second substrate 52 in a region where the second recess 528 is provided.
That is, the second electrode 562 is formed along the concave inner peripheral surface of the second concave portion 528. Thereby, for example, the surface area of the second electrode 562 can be increased as compared with the case where the second electrode 562 is provided on the flat first surface 521 in which the second recess 528 is not provided. For this reason, when a predetermined voltage is applied to the electrostatic actuator 56, the amount of charge that can be held by the second electrode 562 increases, and a large electrostatic attraction can be applied with a small driving voltage. Therefore, the drive voltage required to change the mirror gap by a predetermined dimension can be reduced.

[Second Embodiment]
Next, a second embodiment will be described.
In the first embodiment, the example in which the second recess 528 (micro diaphragm) is provided on the first surface 521 of the second substrate 52 facing the first substrate 51 has been described. On the other hand, in the second embodiment, the position where the micro diaphragm is provided is different from the first embodiment.
FIG. 8 is a cross-sectional view showing a schematic configuration of a wavelength tunable interference filter 5B of the second embodiment. In the following description, the same reference numerals are assigned to the items already described, and the description is omitted or simplified.

In the present embodiment, as shown in FIG. 8, the configuration of the first substrate 51 is the same as that of the first embodiment, and thus the description thereof is omitted here.
In the wavelength tunable interference filter 5B of the present embodiment, the second substrate 52B is wet-etched on the second surface 522 opposite to the first substrate 51, as in the first embodiment, as shown in FIG. The 1st recessed part 523B formed by doing is provided.
A plurality of third recesses 528B are provided at positions that overlap the diaphragm region Ad and the bending portion 526 on the inner circumferential surface of the first recess 523B.

[Operational effects of the second embodiment]
FIG. 9 is a diagram schematically showing the force acting on the second recess 528 in the diaphragm area Ad in the first embodiment, and FIG. 10 shows the third recess 528B in the diaphragm area Ad in the second embodiment. It is a figure which shows typically the force which acts.
In the first embodiment, a second recess 528 is provided on the first surface 521 of the second substrate 52. In this case, when the electrostatic actuator 56 is driven to deform the diaphragm region Ad, the thickness dimension of the position of the second recess 528 becomes smaller than the thickness dimension of the portion where the second recess 528 is not provided. The region Ad can be easily bent. However, as shown in FIG. 9, when the stress P <b> 1 acts in the direction in which the diaphragm region Ad is bent, the moment force P <b> 2 acts in the direction away from the first substrate 51 on the arcuate inner peripheral surface of the second recess 528. .

On the other hand, in the second embodiment, as shown in FIG. 10, when the stress P1 is applied in the direction in which the diaphragm region Ad is bent, the bottom surface portion of the third recess 528B is caused to sink to the first substrate 51 side. In other words, the moment force P3 acts toward the first substrate 51.
Therefore, the directions of the stress P1 and the moment force P3 are both directions toward the first substrate 51, and the diaphragm region Ad can be more easily bent.

[Third embodiment]
Next, as a third embodiment, an optical device including the wavelength variable interference filter 5 of the first embodiment will be described.
FIG. 11 is a cross-sectional view illustrating a schematic configuration of an optical device 600 according to the third embodiment.
As shown in FIG. 11, the optical device 600 includes a housing 610 and a wavelength variable interference filter 5 housed in the housing 610. Here, an example in which the tunable interference filter 5 shown in the first embodiment is housed in the housing 610 is shown, but the tunable interference filter 5B in the second embodiment may be housed.

  The housing 610 includes a base 620 and a lid 630 as shown in FIG. The base 620 and the lid 630 are joined to form an accommodation space therein, and the wavelength variable interference filter 5 is accommodated in the accommodation space.

(Base configuration)
The base 620 is made of, for example, ceramic. The base 620 includes a pedestal portion 621 and a side wall portion 622.
The pedestal portion 621 is configured in a flat plate shape having, for example, a rectangular outer shape in a filter plan view, and a cylindrical side wall portion 622 rises from the outer peripheral portion of the pedestal portion 621 toward the lid 630.

The pedestal 621 includes an opening 623 that penetrates in the thickness direction. The opening 623 includes a region overlapping the first mirror 54 and the second mirror 55 in a plan view of the pedestal 621 viewed from the thickness direction in a state where the wavelength variable interference filter 5 is accommodated in the pedestal 621. Is provided.
Further, a glass member 627 covering the opening 623 is joined to a surface (base outer surface 621B) opposite to the lid 630 of the pedestal 621. Joining of the base portion 621 and the glass member 627 is, for example, low melting point glass joining using a glass frit (low melting point glass) which is a piece of glass melted at a high temperature and rapidly cooled, adhesion by an epoxy resin, or the like. Can be used. In the present embodiment, the housing space is kept airtight in a state where the inside of the housing space is maintained under reduced pressure. Therefore, it is preferable that the base part 621 and the glass member 627 are joined using low melting point glass joining.

Further, an inner terminal portion 624 connected to the first connection electrode 565 and the second extraction electrode 564 of the wavelength variable interference filter 5 is provided on the inner surface (base inner surface 621A) facing the lid 630 of the pedestal portion 621. Yes. The inner terminal portion 624 is connected to the first connection electrode 565 and the second extraction electrode 564 by wire bonding using a wire such as Au. In addition, although wire bonding is illustrated in this embodiment, for example, FPC (Flexible Printed Circuits) may be used.
The pedestal portion 621 has a through hole 625 at a position where the inner terminal portion 624 is provided. The inner terminal portion 624 is connected to the outer terminal portion 626 provided on the base outer surface 621 </ b> B of the pedestal portion 621 through the through hole 625.

  The side wall portion 622 rises from the edge of the pedestal portion 621, and a surface (end surface 622A) facing the lid 630 of the side wall portion 622 provided to surround the base inner side surface 621A is a flat surface parallel to the base inner side surface 621A, for example. It becomes a surface.

  The variable wavelength interference filter 5 is fixed to the base 620 using a fixing material 64 such as an adhesive. At this time, the wavelength variable interference filter 5 may be fixed to the pedestal portion 621 or may be fixed to the side wall portion 622. The fixing material 64 may be provided at a plurality of positions, but the wavelength tunable interference filter 5 is fixed at one place in order to prevent the stress of the fixing material 64 from being transmitted to the wavelength tunable interference filter 5. It is preferable.

(Lid composition)
The lid 630 is a transparent member having a rectangular outer shape in plan view, and is made of, for example, glass.
As shown in FIG. 11, the lid 630 is joined to the side wall portion 622 of the base 620. As this joining method, for example, joining using a low melting point glass can be exemplified.

[Operational effects of the third embodiment]
In the optical device 600 of the present embodiment as described above, the wavelength tunable interference filter 5 is protected by the casing 610, so that the wavelength tunable interference filter 5 can be prevented from being damaged by an external factor.
Further, as described above, the variable wavelength interference filter 5 has a configuration in which the mirror region Am and the diaphragm region Ad are provided in the bottom portion 525 of one first recess 523, and the planar dimensions can be reduced. Accordingly, since the housing 610 for housing such a wavelength variable interference filter 5 can also be reduced in size, the optical device 600 can be reduced in size.

[Fourth embodiment]
Next, as a fourth embodiment, as an example of an electronic apparatus including the wavelength variable interference filters 5, 5A, 5B of the first embodiment or the second embodiment or the optical device 600 of the third embodiment, a printing apparatus ( Printer).

[Schematic configuration of printer]
FIG. 12 is a diagram illustrating an external configuration example of the printer 10 according to the fourth embodiment. FIG. 13 is a block diagram illustrating a schematic configuration of the printer 10 according to the present embodiment.
As shown in FIG. 12, the printer 10 includes a supply unit 11, a transport unit 12, a carriage 13, a carriage moving unit 14, and a control unit 15 (see FIG. 13). The printer 10 controls the units 11, 12, 14 and the carriage 13 based on print data input from an external device 20 such as a personal computer, and prints an image on the medium A. Further, the printer 10 of the present embodiment forms a color patch for color measurement at a predetermined position on the medium A based on preset print data for calibration, and performs spectral measurement on the color patch. As a result, the printer 10 compares the actual measurement value for the color patch with the calibration print data to determine whether or not the printed color has color misregistration. To correct the color.
Hereinafter, each configuration of the printer 10 will be specifically described.

The supply unit 11 is a unit that supplies the medium A to be image formed to the image forming position. The supply unit 11 includes, for example, a roll body 111 (see FIG. 12) around which the medium A is wound, a roll drive motor (not shown), a roll drive wheel train (not shown), and the like. Then, based on a command from the control unit 15, the roll drive motor is rotationally driven, and the rotational force of the roll drive motor is transmitted to the roll body 111 via the roll drive wheel train. As a result, the roll body 111 rotates and the paper surface wound around the roll body 111 is supplied downstream (+ Y direction) in the Y direction (sub-scanning direction).
In the present embodiment, an example in which the paper surface wound around the roll body 111 is supplied is shown, but the present invention is not limited to this. For example, the medium A may be supplied by any supply method such as supplying the medium A such as a sheet of paper loaded on a tray or the like one by one with a roller or the like.

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

The carriage 13 includes a printing unit 16 that prints an image on the medium A, and a spectroscope 17 that performs spectroscopic measurement at a predetermined measurement position T (see FIG. 13) on the medium A.
The carriage 13 is provided by a carriage moving unit 14 so as to be movable along a main scanning direction intersecting with the Y direction.
Further, the carriage 13 is connected to the control unit 15 by a flexible circuit 131, and performs a printing process by the printing unit 16 and a spectroscopic measurement process by the spectroscope 17 based on a command from the control unit 15.
The detailed configuration of the carriage 13 will be described later.

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

Next, the configuration of the printing unit 16 and the spectroscope 17 provided on the carriage 13 will be described with reference to the drawings.
[Configuration of Printing Unit 16]
The printing unit 16 forms an image on the medium A by ejecting ink onto the medium A individually at a portion facing the medium A.
The printing unit 16 is detachably mounted with ink cartridges 161 corresponding to a plurality of colors of ink, and ink is supplied from each ink cartridge 161 to an ink tank (not shown) via a tube (not shown). . Further, nozzles (not shown) for ejecting ink droplets are provided on the lower surface of the printing unit 16 (position facing the medium A) corresponding to each color. For example, piezo elements are arranged in these nozzles, and by driving the piezo elements, ink droplets supplied from the ink tank are ejected and land on the medium A to form dots.

[Configuration of spectrometer]
FIG. 14 is a cross-sectional view showing a schematic configuration of the spectrometer 17.
The spectroscope 17 is an optical module according to the present invention, and includes a light source unit 171, an optical device 600, a light receiving unit 173, and a light guide unit 174 as shown in FIG. 14.
The spectroscope 17 irradiates the measurement position T on the medium A from the light source unit 171 with illumination light, and causes the light component reflected at the measurement position T to enter the optical device 600 through the light guide unit 174. The optical device 600 has the configuration of the third embodiment. The optical device 600 emits (transmits) light having a predetermined wavelength from the reflected light and causes the light receiving unit 173 to receive the light. Further, the optical device 600 can select a transmission wavelength based on the control of the control unit 15, and the spectroscopic measurement of the measurement position T on the medium A can be performed by measuring the amount of light of each wavelength in the visible light. It becomes possible.

[Configuration of light source section]
The light source unit 171 includes a light source 171A and a light collecting unit 171B. The light source unit 171 irradiates the light emitted from the light source 171A into the measurement position T of the medium A from the normal direction with respect to the surface of the medium A.
The light source 171A is preferably a light source that can emit light of each wavelength in the visible light region. As such a light source 171A, for example, a halogen lamp, a xenon lamp, a white LED, and the like can be exemplified, and in particular, a white LED that can be easily installed in a limited space in the carriage 13 is preferable. The condensing unit 171B is configured by, for example, a condensing lens and condenses light from the light source 171A at the measurement position T. In FIG. 14, the condensing unit 171B displays only one lens (condensing lens), but may be configured by combining a plurality of lenses.

[Configuration of light receiving unit and light guiding optical system]
The light receiving unit 173 is disposed on the optical axis of the wavelength variable interference filter 5 and receives light transmitted through the wavelength variable interference filter 5. The light receiving unit 173 outputs a detection signal (current value) corresponding to the amount of received light based on the control of the control unit 15. The detection signal output by the light receiving unit 173 is input to the control unit 15 via an IV converter (not shown), an amplifier (not shown), and an AD converter (not shown).
The light guide unit 174 includes a reflecting mirror 174A and a band pass filter 174B.
The light guide unit 174 reflects the light reflected at 45 ° with respect to the surface of the medium A at the measurement position T onto the optical axis of the wavelength variable interference filter 5 by the reflecting mirror 174A. The band-pass filter 174B transmits light in the visible light range (for example, 380 nm to 720 nm) and cuts ultraviolet light and infrared light. As a result, light in the visible light region is incident on the wavelength variable interference filter 5, and light having a wavelength selected by the wavelength variable interference filter 5 in the visible light region is received by the light receiving unit 173.

[Control unit configuration]
The control unit 15 is a control unit of the present invention, and includes an I / F 151, a unit control circuit 152, a memory 153, and a CPU (Central Processing Unit) 154 as shown in FIG. Yes.
The I / F 151 inputs print data input from the external device 20 to the CPU 154.
The unit control circuit 152 includes control circuits for controlling the supply unit 11, the transport unit 12, the printing unit 16, the light source 171A, the variable wavelength interference filter 5, the light receiving unit 173, and the carriage moving unit 14, respectively. The operation of each unit is controlled based on the command signal. The control circuit of each unit may be provided separately from the control unit 15 and connected to the control unit 15.

The memory 153 stores various programs and various data for controlling the operation of the printer 10.
As various data, for example, V-λ data indicating the wavelength of light transmitted through the variable wavelength interference filter 5 with respect to the voltage applied to the electrostatic actuator 56 when controlling the variable wavelength interference filter 5, and print data For example, print profile data that stores the ejection amount of each ink with respect to the included color data. Moreover, the light emission characteristic (light emission spectrum) with respect to each wavelength of the light source 171A, the light reception characteristic (light reception sensitivity characteristic) with respect to each wavelength of the light receiving unit 173, and the like may be stored.

  The CPU 154 reads out and executes various programs stored in the memory 153, thereby controlling the driving of each unit 11, 12, 14, printing control of the printing unit 16, measurement control by the spectroscope 17 (static control of the wavelength variable interference filter 5). The colorimetric processing based on the spectroscopic measurement result of the spectroscope 17, the correction (update) processing of the print profile data, and the like are performed.

[Operational effects of this embodiment]
The spectroscope 17 of this embodiment includes the optical device 600 described in the third embodiment, and the optical device 600 stores the wavelength variable interference filter 5 described in the first embodiment.
Here, as described above, the wavelength tunable interference filter 5 has a configuration in which the mirror region Am and the diaphragm region Ad are provided in the bottom portion 525 of one first recess 523, and the planar dimensions can be reduced. Accordingly, the optical device 600 can also be reduced in size. Therefore, the spectroscope 17 provided with this can be miniaturized, and the carriage 13 can be miniaturized.
By reducing the size of the carriage 13, the weight of the carriage 13 can be reduced. Therefore, the driving voltage when the carriage 13 is scanned in the sub-scanning direction can be reduced, and the power consumption of the printer 10 can be reduced.

  In the wavelength tunable interference filter 5, the second electrode 562 is provided along the concave inner peripheral surface of the second concave portion 528, so that the mirror gap G is provided as described in the first embodiment. It is possible to reduce the driving voltage required for quantitative change. That is, the driving voltage when the spectroscope 17 sequentially drives light of a plurality of wavelengths can be reduced. In this respect as well, power saving of the printer 10 can be achieved.

[Modification]
It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.

[Modification 1]
In the first embodiment, the configuration in which the first recess 523 is provided on the second surface 522 opposite to the first substrate 51 of the second substrate 52 is illustrated, but the first recess is provided on the first surface 521 side. It is good also as a structure to be made.
FIG. 15 is a cross-sectional view illustrating a schematic configuration of a variable wavelength interference filter 5C according to the first modification.
In the wavelength tunable interference filter 5C shown in FIG. 15, the second substrate 52C includes a first recess 523C formed by performing wet etching on the first surface 521C facing the first substrate 51. As in the first embodiment, the first concave portion 523C includes a bottom portion 525C including the mirror region Am and the diaphragm region Ad, and an arc surface that continues from the outer peripheral edge of the bottom surface of the bottom portion 525C to the first surface 521 of the substrate outer peripheral portion 524. A bending portion 526C including

Further, in such a wavelength variable interference filter 5C, the initial value of the mirror gap from the first mirror 54 to the second mirror 55 becomes large. On the other hand, as shown in FIG. 15, a protrusion 527C that protrudes toward the first mirror 54 is provided on the concave inner side of the first recess 523C, and a second mirror 55 is provided on the protruding front end surface. preferable.
Furthermore, in the wavelength variable interference filter 5C, the dimensions of the first electrode 561 and the second electrode 562 that constitute the electrostatic actuator 56 are also increased. For this reason, as shown in the second embodiment, it is preferable to provide a third recess 528C on the second surface 522C side of the second substrate 52C so that the diaphragm region Ad is easily bent.

[Modification 2]
In 1st embodiment, although the protrusion part 527 showed the example which protrudes in the 1st board | substrate 51 side rather than the 1st surface 521, it is not limited to this. FIG. 16 is a cross-sectional view showing a schematic configuration of a wavelength tunable interference filter 5D according to Modification 2.
In the variable wavelength interference filter 5D shown in FIG. 16, the second substrate 52D is formed by performing wet etching on the second surface 522 opposite to the first substrate 51, as in the first embodiment. One recess 523D is provided. In the first recess 523D, the surface of the bottom 525D that faces the first substrate 51 constitutes a flat first surface 521. That is, the protruding portion 527 that protrudes from the first surface 521 toward the first substrate 51 is not provided. Instead, a protrusion 527D that protrudes in a direction away from the first substrate 51 is provided on the surface opposite to the first surface 521 of the bottom 525D (the inner periphery of the first recess 523D).

  For example, the protrusion 527D performs wet etching on the upper surface M22 of the second glass substrate M2 that is the base material of the second substrate 52D, and digs up to the depth of the protrusion 527D. Thereafter, the first recess 523D is formed by further etching using the resist in which the diaphragm region Ad is opened. The second etching process may be dry etching or wet etching. When wet etching is performed, a curved portion is formed between the mirror region Am and the diaphragm region Ad, but the protruding size of the protruding portion 527D is smaller than the depth size of the first recessed portion 523D. For this reason, similarly to the wavelength variable interference filter 5A shown in FIG. 4, the planar dimension can be reduced as compared with the conventional wavelength variable interference filter 5f.

FIG. 17 is a cross-sectional view showing a schematic configuration of another wavelength variable interference filter 5E according to Modification 2. As shown in FIG. 17, the second substrate 52 </ b> E includes both a protruding portion 527 that protrudes toward the first substrate 51 in the mirror region Am and a protruding portion 527 </ b> D that protrudes away from the first substrate 51. Also good.
In order to suppress the bending of the mirror area Am of the bottom 525E, the thickness dimension of the mirror area Am is set to 3 to 4 times the thickness dimension of the diaphragm area Ad as described above. Therefore, if the projecting dimensions of these projecting portions 527 and 527D are set to be approximately the thickness dimension of the diaphragm area Ad, the thickness dimension of the mirror area Am is the same as that of the wavelength variable interference filter 5D shown in the first embodiment or FIG. It can be a dimension.
In the variable wavelength interference filter 5E shown in FIG. 17, the etching amount for forming the protrusions 527 and 527D can be reduced. Therefore, even when the protrusions 527 and 527D are formed by wet etching, the planar dimension of the curved portion formed between the protrusions 527 and 527D and the diaphragm region Ad can be further reduced, and the wavelength variable interference shown in FIG. As compared with the filter 5A, the wavelength variable interference filter 5E having a smaller planar dimension can be provided.

[Modification 3]
In the first embodiment, the first substrate 51 corresponds to the counter substrate of the present invention, and the first electrode 561 provided on the first substrate 51 and the second electrode 562 provided on the second substrate 52 are electrostatically connected. An example in which the actuator 56 is configured is shown. On the other hand, the counter substrate is not limited to the first substrate 51 facing the first surface 521 of the second substrate 52.
FIG. 18 is a cross-sectional view illustrating an example of a wavelength tunable interference filter 5G according to Modification 3.
The variable wavelength interference filter 5G is disposed on the opposite side of the first substrate 51, the second substrate 52G disposed opposite to the first substrate 51, and the first substrate 51 of the second substrate 52G. And a third substrate 51G constituting the counter substrate.
In the present embodiment, the second substrate 52G is provided with a third recess 528B on the inner peripheral surface of the recess of the first recess 523G, as in the second embodiment. A second electrode 562G is provided in the third recess 528B. Therefore, as in the first embodiment, the surface area of the second electrode 562G can be increased.

The third substrate 51G has, for example, a flat plate shape with a uniform thickness dimension, and a third electrode 566 is provided at a position facing the second electrode 562G of the second substrate 52G.
In such a configuration, the first electrostatic actuator 56 is configured by the first electrode 561 and the second electrode 562G. The second electrode 562G and the third electrode 566 constitute a second electrostatic actuator 56G.
In such a configuration, by driving the first electrostatic actuator 56, the second mirror 55 can be displaced in the direction of decreasing the mirror gap G, and by driving the second electrostatic actuator 56G. The second mirror 55 can be displaced in the direction of increasing the mirror gap G.
In the example shown in FIG. 18, the second electrode 562G is provided on the concave inner peripheral surface of the first concave portion 523G. However, for example, it may be provided on the first surface 521 of the second substrate 52G. Moreover, the 2nd electrode 562G may be provided in the concave inner peripheral surface of the 1st recessed part 523G, and the 1st surface 521 of the 2nd board | substrate 52G, respectively. In this case, the first electrostatic actuator 56 is configured by the second electrode 562G on the first surface 521 and the first electrode 561, and the second electrode 562G and the third electrode provided on the inner circumferential surface of the first recess 523G. The electrode 566 can constitute a second electrostatic actuator 56G.

[Modification 4]
In the first embodiment, an example in which the second recess 528 is provided on the surface (first surface 521) of the second substrate 52 facing the first substrate 51, and in the second embodiment, the first substrate of the second substrate 52 is provided. The example which provided the 3rd recessed part 528B in the surface on the opposite side to 51 (the recessed inner peripheral surface of the 1st recessed part 523B) was shown. On the other hand, it is good also as a structure which provides both the 2nd recessed part 528 and the 3rd recessed part 528B.

[Modification 5]
In 1st embodiment, although the example formed by etching the lower surface M21 of the 2nd glass substrate M2 was shown as the protrusion part 527, it is not limited to this. For example, a translucent film material whose refractive index is substantially the same as that of the second substrate 52 (second glass substrate M2) with respect to the first surface 521 of the second substrate 52 (lower surface M21 of the second glass substrate M2). The protruding portion 527 may be formed by stacking.

[Modification 6]
In the above embodiment, the position where the second recessed portion 528 is provided is the region overlapping the diaphragm region Ad and the curved portion 526 in the first recessed portion 523, but as described above, it is provided only in the region overlapping the diaphragm region Ad. Alternatively, it may be provided only in a region overlapping with the bending portion 526. The same applies to the third recesses 528B and 528C.
That is, in the wavelength variable interference filter 5 as in the first embodiment, when changing the mirror gap G, the diaphragm region Ad can be easily bent, so that the bending of the mirror region Am can be suppressed. Therefore, even if the second recessed portion 528 is not provided in the region overlapping with the curved portion 526, bending of the mirror region Am can be suitably suppressed by providing the second recessed portion 528 in the diaphragm region Ad.
On the other hand, the diaphragm region Ad is smaller in thickness and weaker than the other part of the second substrate 52. If the second concave portion 528 and the third concave portions 528B and 528C having a smaller thickness dimension are provided in this portion, there is a possibility that a crack may occur. On the other hand, the bending portion 526 has a larger thickness dimension than the diaphragm region Ad. For this reason, in the structure which provides the 2nd recessed part 528 and 3rd recessed part 528B, 528C only in the position which overlaps with the curved part 526, damage to the diaphragm area | region Ad can be suppressed.

[Modification 7]
In the third embodiment, the configuration of the optical device 600 has been illustrated, but the optical device 600 is not limited to the shape of the third embodiment. For example, the wavelength variable interference filter 5 may be held inside a cylinder of a cylindrical casing.
In the fourth embodiment, the printer 10 is illustrated as an example of the electronic device, but the present invention is not limited thereto. Examples of the electronic device provided with the wavelength tunable interference filter 5 include a light source device (for example, a laser light source device) that outputs light having a desired wavelength, a spectroscopic analyzer that analyzes components contained in a measurement object, and the like. The light source device and the analysis device may be mounted on a wearable device or the like.

  In addition, the specific structure for carrying out the present invention can be appropriately changed to other structures and the like within a range in which the object of the present invention can be achieved.

  5, 5A, 5B, 5C, 5D, 5E, 5G ... wavelength variable interference filter, 10 ... printer (electronic device), 17 ... spectroscope, 51 ... first substrate (counter substrate), 51G ... third substrate (counter substrate) ), 52, 52B, 52C, 52D, 52E, 52G ... second substrate (substrate), 54 ... first mirror, 55 ... second mirror, 56 ... electrostatic actuator, 56G ... second electrostatic actuator, 521 521C: first surface, 522, 522C ... second surface, 523, 523B, 523C, 523D, 523G ... first recess, 525, 525A, 525C, 525D, 525E ... bottom, 526, 526A, 526C ... curved portion, 527 , 527C, 527D ... protrusion, 528 ... second recess, 528B, 528C ... third recess, 561 ... first electrode, 562,562G ... second electrode, 566 Third electrode, 600 ... optical device, 610 ... chassis, Am ... mirror area, Ad ... diaphragm region, O ... filter center axis.

Claims (8)

The first mirror,
A second mirror facing the first mirror, a first surface facing the first mirror and a substrate having a second surface opposite to the first surface, and
At least one of the first surface and the second surface of the substrate is provided with a first concave portion having a bottom portion and a curved portion that curves from the outer periphery of the bottom portion toward the outer periphery of the substrate,
The bottom portion includes a mirror region that overlaps the first mirror and the second mirror in a plan view as viewed from the thickness direction of the substrate, and a diaphragm region that is disposed on an outer periphery of the mirror region. Variable interference filter. The tunable interference filter according to claim 1,
The substrate has a protruding portion that protrudes from the first surface toward the first mirror in the mirror region of the bottom portion, and a protruding tip is a flat surface facing the first mirror,
The said 2nd mirror is provided in the plane facing the said 1st mirror of the said protrusion part. The variable wavelength interference filter characterized by the above-mentioned. In the wavelength tunable interference filter according to claim 1 or 2,
The first surface of the substrate is provided with a second recess having a smaller area in the plan view than the first recess in a region other than the mirror region in the region overlapping the first recess in the plan view. A tunable interference filter characterized by The tunable interference filter according to claim 3,
A counter substrate facing the first surface of the substrate;
A first electrode provided on the counter substrate;
A second electrode provided on the first surface of the substrate, in a region other than the mirror region in a region overlapping the first recess in the plan view, and in a position overlapping the first electrode;
A wavelength tunable interference filter comprising: In the wavelength tunable interference filter according to claim 1 or 2,
A wavelength tunable interference filter, wherein a surface of the first recess of the substrate other than the mirror region is provided with a third recess whose area in plan view is smaller than that of the first recess. The wavelength variable interference filter according to any one of claims 1 to 5,
A housing that houses the variable wavelength interference filter;
An optical device comprising: The wavelength variable interference filter according to any one of claims 1 to 5,
An electronic device comprising: a control unit that controls driving of the wavelength variable interference filter. A wavelength provided with a first mirror and a substrate having a second mirror facing the first mirror and having a first surface facing the first mirror and a second surface opposite to the first surface. A method of manufacturing a variable interference filter,
A recess that forms, on at least one of the first surface and the second surface of the substrate, a first recess having a bottom portion and a curved portion that curves from the outer periphery of the bottom portion toward the outer periphery of the substrate by wet etching. Forming step;
A second mirror forming step of forming the second mirror at a position overlapping the first mirror in a plan view as viewed from the thickness direction of the substrate;
A method of manufacturing a wavelength tunable interference filter, characterized in that:

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