WO2016157419A1

WO2016157419A1 - Optical scanner

Info

Publication number: WO2016157419A1
Application number: PCT/JP2015/060161
Authority: WO
Inventors: 良輔下澤; 満小荒井
Original assignee: パイオニア株式会社; パイオニア・マイクロ・テクノロジー株式会社
Priority date: 2015-03-31
Filing date: 2015-03-31
Publication date: 2016-10-06

Abstract

The purpose of the present invention is to provide an optical scanner that allows the reflection within a scanning range from a region outside a mirror to be suitably reduced. A MEMS mirror (100) according to the present invention scans the light reflected from a mirror part (3) within a prescribed angle range by causing the mirror part (3) that reflects light incident thereon to pivot. The MEMS mirror includes a fixed frame (1), a frame part (2), and a protrusion pattern (7). The frame part (2) is coupled to the mirror part (3) and causes the mirror part (3) to pivot. The fixed frame (1) movably supports the frame part (2). The protrusion pattern (7) is provided on the surfaces of the fixed frame (1) and the frame part (2) at which incident light enters, reflects the incident light, and creates first order diffracted light caused by the reflection outside of the range of scanning angle.

Description

Optical scanner

The present invention relates to an optical scanner for driving a mirror.

Conventionally, MEMS (Micro Electro Mechanical System) devices manufactured by semiconductor process technology are known. For example, in Patent Document 1, in a MEMS optical scanner, a region other than a mirror formed on the surface of a silicon substrate is provided with a fine concavo-convex structure at a pitch equal to or less than the wavelength of laser light irradiated on the mirror. A technique for suppressing laser light from being reflected in a region excluding a mirror and becoming stray light is disclosed.

JP 2013-225075 A

In Patent Document 1, by providing a fine concavo-convex structure having a bitch periodic structure below the wavelength of light on the surface of a smooth substrate or the like, the refractive index, which is a characteristic value of the material, is asymptotically changed to be small. The same effect is exhibited and the light reflectance of the surface is reduced. In order to form such a fine concavo-convex structure on the surface of the substrate, it has been disclosed to use a reactive ion etching technique, but this complicates the manufacturing process of the MEMS optical scanner, and costs are reduced. There is a problem of inviting up.

Examples of the problem to be solved by the present invention include the above. The main object of the present invention is to provide an optical scanner capable of suitably reducing reflection into the scanning range.

The invention described in claim is an optical scanner that scans light reflected by the mirror unit in a predetermined angle range by swinging a mirror unit that reflects incident light, and is coupled to the mirror unit. A drive unit that swings the mirror unit, a support unit that supports the drive unit so as to be displaceable, and a surface of the drive unit or the support unit on the incident light incident side. A reflection type diffraction grating that reflects the incident light that is incident and generates first-order diffracted light by the reflection outside the predetermined angle range.

The perspective view of a MEMS mirror is shown. The top view of the MEMS mirror which illustrated the dummy pattern is shown. FIG. 2 shows a top view of a MEMS mirror illustrating magnetic field lines. It is the figure which showed a mode that a laser beam injects into a flame | frame part. The front view of the MEMS mirror provided with the position detection function of a mirror part is shown. It is sectional drawing which showed the manufacturing process of the flame | frame part in time series. It is sectional drawing which showed the manufacturing process of the flame | frame part in time series. The perspective view of a MEMS mirror at the time of forming a dummy pattern according to the shape of a scanning region is shown. The front view of the MEMS mirror which concerns on the modification 3, and the enlarged view of the sensor part vicinity are shown.

In one preferred embodiment of the present invention, an optical scanner that scans light reflected by the mirror unit in a predetermined angle range by swinging a mirror unit that reflects incident light, the mirror unit And a drive unit that swings the mirror unit, a support unit that supports the drive unit in a displaceable manner, and is formed on the surface of the drive unit or the support unit on the side on which the incident light is incident, A reflective diffraction grating that reflects the incident light incident on the surface and generates first-order diffracted light by the reflection outside the predetermined angle range.

The optical scanner scans the light reflected by the mirror in a predetermined angle range by swinging the mirror that reflects incident light, and includes a drive unit, a support unit, and a reflection type diffraction. And a lattice. The drive unit is connected to the mirror unit and swings the mirror unit. A support part supports a drive part so that a displacement is possible. The reflection type diffraction grating reflects incident light incident on the drive unit or the support unit on the incident light incident side, and generates first-order diffracted light due to the reflection outside the scanning angle range. According to this aspect, the optical scanner can cause a part of the reflected light from the drive unit and the support unit to be suitably generated outside the scanning angle range even when the drive unit and the support unit are irradiated with light. it can. Therefore, the influence resulting from the reflected light from the drive unit or the support unit can be suitably reduced.

In one aspect of the optical scanner, a wiring pattern for supplying electric energy for swinging the mirror unit to the driving unit is provided, and the reflective diffraction grating is the wiring pattern or a manufacturing process of the wiring pattern. The dummy pattern is formed at the same time as the wiring pattern and has no function of supplying the electric energy. In this aspect, the reflection type diffraction grating can be suitably formed at low cost without complicating the manufacturing process of the optical scanner, and the reflected light from the drive unit and the support unit into the scanning range can be reduced.

In another aspect of the optical scanner, at least a part of the reflective diffraction grating is constituted by a wiring pattern in which a coil is formed on the surface of the drive unit. As described above, when the optical scanner is of the electromagnetic drive type, the reflection type diffraction grating is suitably formed by the wiring pattern, and the reflected light from the drive unit and the support unit within the scanning range can be reduced.

In another aspect of the optical scanner, the optical scanner scans light reflected by the mirror unit on a two-dimensional projection surface, and the reflective diffraction grating extends in a longitudinal direction of a scanning range on the projection surface. A plurality of the dummy patterns extending in the corresponding first direction are arranged side by side in a second direction perpendicular to the first direction. According to this aspect, it is possible to preferably relax the conditions relating to the pitch of the projections and depressions for causing the reflective diffraction grating to generate the first-order diffracted light outside the scanning angle range, and it is possible to deal with a wide range of semiconductor manufacturing process rules.

In another aspect of the optical scanner, the driving unit includes a sensor unit that detects a swing of the mirror unit, and the reflective diffraction grating is formed on a surface of the sensor unit. According to this aspect, even when the sensor unit is irradiated with light, a part of the reflected light from the sensor unit can be suitably generated outside the scanning angle range.

In another aspect of the optical scanner, the optical scanner includes a metal thin film that shields the incident light on a surface of the reflective diffraction grating. According to this aspect, it is possible to suitably suppress the occurrence of an influence on the detection value of the sensor unit due to the irradiation of the sensor unit.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

[Configuration of MEMS mirror]
FIG. 1 is a perspective view of a MEMS mirror 100 which is an aspect of the “optical scanner” of the present invention. The MEMS mirror 100 is an electromagnetic MEMS mirror, and a main part is manufactured on a silicon substrate by a semiconductor integrated circuit manufacturing technique. The MEMS mirror 100 mainly includes a fixed frame 1, a frame portion 2, a mirror portion 3, magnets 4A to 4D,

X-axis torsion bars

5A and 5B, and Y-

axis torsion bars

6A and 6B. Hereinafter, the direction in which the

X-axis torsion bars

5A and 5B extend is the “X-axis direction”, the direction perpendicular to the X-axis in which the Y-

axis torsion bars

6A and 6B extend is the “Y-axis direction”, and the X and Y axes. A direction perpendicular to the “Z-axis direction” is defined, and each positive direction is determined as illustrated.

The fixed frame 1 is a structure for supporting the frame portion 2 and is formed of a metal material or a semiconductor material such as silicon. The fixed frame 1 has a frame shape with a gap inside. A convex pattern 7 is formed on the surface of the fixed frame 1. As will be described later, the convex pattern 7 is formed of a wiring pattern 7A for supplying a current supplied from an external current source (not shown) to the frame portion 2 and a dummy pattern 7B that does not pass a current. At least one end of the dummy pattern 7B is not connected to any electrode. The fixed frame 1 is an example of the “supporting portion” in the present invention, and the uneven region formed by the convex pattern 7 is an example of the “reflective diffraction grating” in the present invention.

The frame part 2 has a frame shape with a gap inside. The frame portion 2 is connected to the fixed frame 1 via two

X-axis torsion bars

5A and 5B extending in the X-axis direction. The frame portion 2 can swing (rotate) with respect to the fixed frame 1 with the X axis as a rotation axis. A convex pattern 7 is formed on the surface of the frame portion 2. The wiring pattern 7A extending from the fixed frame 1 via the

X-axis torsion bars

5A and 5B forms a coil on the surface of the frame part 2 along the frame shape of the frame part 2. The frame unit 2 is an example of the “drive unit” in the present invention.

The mirror unit 3 is a disk-shaped member on the surface of which a reflection film that reflects incident light is formed, and is attached to the frame unit 2 via two Y-

axis torsion bars

6A and 6B extending in the Y-axis direction. It is connected. The mirror unit 3 is swingable with respect to the frame unit 2 with the Y axis as a rotation axis.

The

X-axis torsion bars

5A and 5B and the Y-

axis torsion bars

6A and 6B are elastic members such as springs made of silicon, metal, resin, or the like. The magnets 4A to 4D are arranged around the frame portion 2 and generate magnetic fields in the X-axis direction and the Y-axis direction in a region where coils formed in the frame portion 2 are present. In FIG. 1, the magnet 4A and the magnet 4C are disposed at a position where the fixed frame 1 is sandwiched in the Y-axis direction, and the magnet 4B and the magnet 4D are disposed at a position where the fixed frame 1 is sandwiched in the X-axis direction.

2 and 3 are top views of the MEMS mirror 100. FIG. In FIG. 2, the wiring pattern 7A is indicated by a solid line, and the dummy pattern 7B is indicated by a broken line. Further, FIG. 3 shows only the wiring pattern 7A without showing the dummy pattern 7B, and illustrates the magnetic force lines Ax and Ay generated by the wiring pattern 7A.

As shown in FIGS. 2 and 3, the wiring pattern 7 A extending from the fixed frame 1 via the X-axis torsion bars 5 A and 5 B is formed so as to circulate around the outer edge of the frame portion 2. A coil is formed on the surface. Thereby, the wiring pattern 7A generates a magnetic field in the X-axis direction indicated by the magnetic force line Ax and a magnetic field in the Y-axis direction indicated by the magnetic force line Ay, respectively.

In addition, as shown in FIG. 2, the dummy pattern 7B has parallel projections and depressions formed by the convex patterns 7 (that is, the wiring patterns 7A and the dummy patterns 7B) on the surfaces of the fixed frame 1 and the frame portion 2 at a predetermined period. It is formed to line up. Thereby, the convex pattern 7 forms a reflection type diffraction grating on the surfaces of the fixed frame 1 and the frame portion 2. The function of this diffraction grating will be described in detail in the section “Reflection reduction processing”.

[Operation of MEMS mirror]
Next, the operation | movement aspect of the MEMS mirror 100 of a present Example is demonstrated.

During the operation of the MEMS mirror 100, a desired driving current is supplied to the coils formed in the frame unit 2 from an external current source via the wiring pattern 7A at a desired timing. The driving current includes a current component (also referred to as “X-axis driving current component”) for rotating the frame unit 2 about the X axis as a rotation axis and a mirror unit 3 for rotating the mirror unit 3 about the Y axis as a rotation axis. Current component (also referred to as “Y-axis drive current component”). In the present embodiment, the frame unit 2 rotates at an arbitrary frequency (for example, 60 Hz) with the X axis as a rotation axis. In this case, the X-axis drive current component preferably includes an alternating current including the same frequency as the rotation frequency with the X axis as the rotation axis.

A magnetic field in the Y-axis direction is applied to the coil formed in the frame portion 2 from two

magnets

4A and 4C arranged in the Y-axis direction with the fixed frame 1 interposed therebetween. Therefore, in a state where the driving current is supplied, Lorentz force is generated in the coil due to electromagnetic interaction between the X-axis driving current component and the magnetic field in the Y-axis direction. Thereby, the frame unit 2 rotates about the X axis as a rotation axis. Here, since the current component for driving the X-axis is alternating current, the rotation direction is reversed every predetermined period, and the frame portion 2 swings.

Further, in this embodiment, the mirror unit 3 rotates about the Y axis as a rotation axis by a resonance frequency determined by the mirror unit 3 and the two Y

axis torsion bars

6A and 6B. Specifically, the Y axis is rotated about the rotation axis by a resonance frequency (for example, 15 kHz) determined by the moment of inertia around the Y axis of the mirror unit 3 and the torsion spring constants of the Y

axis torsion bars

6A and 6B. In this case, the Y-axis drive current component includes an AC current having the same frequency as an AC current including a signal component having a frequency 1 / N times ("N" is an integer) the rotation frequency with the Y axis as the rotation axis. It is preferable.

On the other hand, a magnetic field in the X-axis direction is applied to the coils formed in the frame portion 2 from two

magnets

4B and 4D arranged side by side in the X-axis direction with the fixed frame 1 interposed therebetween. Therefore, in a state where the driving current is supplied, a Lorentz force is generated in the coil due to electromagnetic interaction between the Y-axis driving current component and the magnetic field in the X-axis direction. Thereby, one side extending in the Y-axis direction of the frame portion 2 moves in the Z-axis positive direction with respect to the fixed frame 1, and one side facing it moves in the Z-axis negative direction. At this time, since the

X-axis torsion bars

5A and 5B are elastic bodies, the movement of the side extending in the Y-axis direction of the frame portion 2 in the Z-axis direction is not completely restricted. That is, in this case, the X-axis torsion bars 5 A and 5 B are deformed, so that the frame portion 2 is inclined with respect to the fixed frame 1. Here, since the current component for driving the X-axis is alternating current, the inclination direction of the frame portion 2 with respect to the fixed frame 1 is reversed every predetermined period. As described above, when the frame portion 2 is tilted while being inverted periodically, the mirror portion 3 swings with respect to the frame portion 2 with the Y axis as the rotation axis at the resonance frequency described above.

In this manner, the mirror part 3 swings about the X axis and the Y axis as rotation axes by flowing the current component for driving the X axis and the current component for driving the Y axis superimposed on the coil formed in the frame part 2. To do. Thereby, the mirror part 3 can scan the incident light on the projection surface which is a two-dimensional space.

[Reflection reduction processing]
In the present embodiment, the convex pattern 7 formed on the surfaces of the fixed frame 1 and the frame portion 2 functions as a reflective diffraction grating. As a result, the image quality degradation of the drawn image caused by the reflected light from the fixed frame 1 and the frame unit 2 entering the scanning region of the mirror unit 3 is suitably reduced.

The MEMS mirror 100 reflects the condensed laser light by the mirror unit 3 and scans a predetermined range on a projection surface such as a screen as a scanning region. However, since there is a theoretical limit in condensing the laser beam, when the mirror unit 3 is small, the fixed frame 1 and the frame unit 2 other than the mirror unit 3 may be irradiated with the laser beam. . When high-intensity reflected light from the fixed frame 1 and / or the frame unit 2 enters the scanning region of the MEMS mirror 100, there arises a problem that the image quality of an image drawn in the scanning region is deteriorated.

In consideration of the above, in the present embodiment, a reflection type diffraction grating is formed by the wiring pattern 7A and the dummy pattern 7B on the surfaces of the fixed frame 1 and the frame portion 2 that can be irradiated with the laser beam. This diffraction grating is configured by the unevenness of the wiring pattern 7A and the dummy pattern 7B being arranged in parallel at a predetermined period. Here, since the wiring pattern 7A constituting the coil is arranged so as to circulate on the surface of the frame portion 2, it is suitable for constituting a diffraction grating. In addition, in a region where the wiring pattern 7A constituting the coil does not exist, a dummy pattern 7B in which at least one end is not connected to any electrode and current does not flow is disposed.

In this case, the light reflected by the adjacent convex portions of the diffraction grating strengthens the intensity in a predetermined angle range and weakens the intensity in another predetermined angle range due to light interference. That is, the reflected light reflected by the diffraction grating becomes diffracted light corresponding to each order such as 0th order diffracted light, ± 1st order diffracted light, and ± 2nd order diffracted light.

In this embodiment, the diffracted light of each order after ± 1st order excluding the 0th order is outside the range of the mirror unit 3 and the scanning angle (that is, the space specified by the region connecting the mirror unit 3 and the outer edge of the scanning region) As described above, the convex patterns 7 are arranged at an appropriate pitch in accordance with the wavelength of the irradiated laser beam. This will be described with reference to FIG.

FIG. 4 is a diagram showing a state in which laser light is incident on the convex pattern 7 formed on the frame portion 2. In the example of FIG. 4, for the solid light beams La to Lc indicating the laser light incident on the convex pattern 7, the one-dot chain light beams Laa, Lba and Lca indicating the −1st order diffracted light and the primary light are respectively shown. Two-dot chain rays Ray, Lbb, and Lcb are shown. A region 70 indicates a range of scanning angles of the mirror unit 3.

Here, as shown in FIG. 4, the incident angle of the incident light is “φ”, the pitch (grating constant) of the convex pattern 7 is “d”, and the traveling angle of the first-order diffracted light with respect to the normal line of the diffraction grating is “θ1”. When the traveling angle of the −1st order diffracted light with respect to the normal line is “θ2” and the wavelength of the incident light is “λ”, the following equations (1) and (2) are established according to the grating equation.
d × (sin θ 1 −sin φ) = λ Formula (1)
d × (sin θ2−sinφ) = − λ Formula (2)
Here, as shown in FIG. 4, when the scanning angle (full angle) by the mirror unit 3 is “α”, the first-order diffracted light is not generated within the scanning range. ) And Expression (4) are satisfied.
θ1> φ + α / 2 Formula (3)
θ2 <φ−α / 2 Formula (4)
Therefore, for example, when “λ = 450 nm”, “α = 50 °”, and “φ = 10 °”, “θ1> 35 °” is obtained based on Equation (3), and this relationship is applied to Equation (1). Then, “d <1.13 μm” is obtained. Further, since “θ2 <−15 °” based on the equation (4), when this relationship is applied to the equation (2), “d <1.07 um” is obtained. Therefore, in this case, the convex pattern 7 may be arranged so that “d <1.07 nm”.

As described above, in this embodiment, the pitch d is appropriately determined based on the equations (1) to (4), and the diffraction grating constituted by the convex pattern 7 is irradiated with the laser light other than the mirror unit 3 ( In this embodiment, they are arranged on the fixed frame 1 and the frame part 2). Accordingly, it is possible to prevent the diffracted light after the ± first-order light into the scanning range from entering the scanning angle range, and to appropriately reduce the amount of unnecessary reflected light into the scanning angle range.

Further, as will be described later in the section of [Manufacturing Process], the dummy pattern 7B is formed in a process of forming a wiring pattern 7A for supplying a current for driving the mirror unit 3 required in the process of manufacturing the MEMS mirror 100. The wiring pattern 7A can be formed at the same time. Therefore, it is possible to add a diffraction grating that reduces unnecessary reflection into the scanning region without complicating the manufacturing process of the conventional MEMS mirror 100.

[Mirror position detection structure]
In the MEMS mirror 100, a piezoresistive element or the like is preferably disposed in the vicinity of the Y-

axis torsion bars

6A and 6B that support the mirror unit 3, and the mirror unit 3 that is generated according to the twist of the Y-

axis torsion bars

6A and 6B. The rotational position based on the amount of displacement is configured to be detectable.

FIG. 5 shows a front view of the MEMS mirror 100 having a function of detecting the position of the mirror unit 3 and an enlarged view of the vicinity of the Y-axis torsion bar 6B. A sensor unit 20 including a piezoresistive element for detecting the rotational position of the mirror unit 3 is provided in the vicinity of the Y-axis torsion bar 6B of the frame unit 2 of the MEMS mirror 100 shown in FIG. In the sensor unit 20, an aluminum layer 25, which is an example of a light-shielding metal thin film, is formed on the surface of the piezoresistive element in order to suppress the influence of the photoelectric effect when the piezoresistive element is irradiated with light. Here, since the aluminum layer 25 which is a metal thin film has a high light reflectance, the reflected light of the laser light irradiated onto the aluminum layer 25 may be reflected to the scanning region of the MEMS mirror 100. Therefore, in the sensor part 20 shown in FIG. 5, the unevenness | corrugation of a predetermined pitch is formed so that the aluminum layer 25 may comprise a diffraction grating. Here, similarly to the pitch of the convex pattern 7, the pitch of the aluminum layer 25 is set to a width that satisfies the expressions (1) to (4) so that diffracted light after ± 1st order light does not enter the scanning region. Is set.

As described above, the aluminum layer 25 has a light shielding function to the piezoresistive element and also functions as a diffraction grating. Thereby, it can suppress that the reflected light in the sensor part 20 injects into the scanning area | region of the MEMS mirror 100. FIG. The specific configuration of the sensor unit 20 will be described in detail in the following [Manufacturing process] section.

[Manufacturing process]
Next, the manufacturing process of the frame part 2 including the sensor part 20 described in FIG. 5 will be described with reference to FIGS. 6 and 7 are diagrams showing the state of each manufacturing process (first to seventh processes) of the frame part 2 in time series. Here, FIG. 6 shows a cross-sectional view of the frame portion 2 along the two-dot chain line A in FIG. 5, and FIG. 7 shows a cross-sectional view of the frame portion 2 along the one-dot chain line B.

First, in the first step, as shown in FIGS. 6 (A) and 7 (A), a molded silicon substrate 21 to be a substrate of the frame portion 2 is placed. Further, in the region where the sensor unit 20 is formed, the piezoresistive element 22 is formed on the silicon substrate 21 by a diffusion method, ion implantation, or the like, as shown in FIG.

Next, in the second step, as shown in FIGS. 6B and 7B, a silicon oxide film 23 is formed on the entire surface of the silicon substrate 21 by a chemical vapor deposition (CVD) method or the like.

In the third step, as shown in FIGS. 6C and 7C, the silicon oxide film 23 is masked with a photoresist and subjected to dry etching or the like, so that a contact hole is formed on the piezoresistive element 22. 30 is opened. In this case, simultaneously with the opening of the contact hole 30, the concave portions 31 having a predetermined pitch that constitute the diffraction grating are opened on the piezoresistive element 22. Thereby, the uneven structure for constituting a diffraction grating can be formed on the sensor part 20 without adding a process.

Next, in the fourth step, as shown in FIGS. 6D and 7D, an aluminum layer 24 is formed on the entire surface by sputtering or the like. Then, in the fifth step, as shown in FIGS. 6E and 7E, the convex pattern 7 is formed by masking the aluminum layer 24 with a photoresist and performing dry etching or the like. In this case, by forming the dummy pattern 7B that constitutes the diffraction grating at the same time as the wiring pattern 7A, the diffraction grating can be constituted without adding a process.

Next, in the sixth step, as shown in FIGS. 6F and 7F, a silicon oxide film 23 functioning as an insulating layer is formed on the entire surface by sputtering or the like by sputtering or the like. In the final seventh step, as shown in FIGS. 6 (G) and 7 (G), after forming the aluminum layer 25 on the entire surface, it is masked with a photoresist and subjected to dry etching or the like, whereby a piezoresistive element is formed. An aluminum layer 25 that functions as a light-shielding layer is formed on the surface. The aluminum layer 25 functions as a diffraction grating having irregularities with a predetermined pitch, and does not generate diffracted light of orders of ± 1st order or later within the scanning angle range.

In addition, the manufacturing process shown in FIG.6 and FIG.7 is an example, Comprising: The process of manufacturing the MEMS mirror 100 which concerns on this invention is not limited to this. Even when the MEMS mirror 100 is manufactured by using another process, a concavo-convex structure (that is, a dummy pattern 7B) for forming a diffraction grating in a process necessary to form the contact hole 30 and the wiring pattern 7A. And recesses 31) are formed. Thereby, it is possible to add a diffraction grating that reduces unnecessary reflection into the scanning range without complicating the manufacturing process of the conventional MEMS mirror 100.

As described above, the MEMS mirror 100 according to the present embodiment scans the light reflected by the mirror unit 3 in a predetermined angle range by swinging the mirror unit 3 that reflects incident light. The fixed frame 1, the frame portion 2, and the convex pattern 7 are provided. The frame unit 2 is connected to the mirror unit 3 and swings the mirror unit 3. The fixed frame 1 supports the frame part 2 so as to be displaceable. The convex pattern 7 is provided on the surfaces of the fixed frame 1 and the frame portion 2 on the side where incident light is incident, reflects incident incident light, and generates first-order diffracted light due to the reflection outside the scanning angle range. Thereby, the MEMS mirror 100 can suppress suitably the deterioration of the image quality etc. resulting from the reflected light of the fixed frame 1 and the frame part 2 entering into a scanning area | region.

The above-described MEMS mirror 100 of the present embodiment can be applied to various electronic devices including, for example, a head-up display, a head-mounted display, a laser scanner, and a laser printer.

[Modification]
Next, a modified example suitable for the above embodiment will be described. The following modifications may be applied to the above-described embodiments in combination.

(Modification 1)
According to the relations of the equations (1) to (4) described in the section of “reflection reduction processing”, the pitch d of the diffraction grating can be set to a larger value as the angle α is smaller. For this reason, when the scanning region is rectangular, the dummy pattern 7B may be formed so that the direction of the diffraction grating (that is, the direction in which the convex portion extends) matches the longitudinal direction of the scanning region.

FIG. 8 is a perspective view of the MEMS mirror 100A when the dummy pattern 7B is formed according to the shape of the scanning region. In the example of FIG. 8, the MEMS mirror 100A has a rectangular scanning region 71 whose longitudinal direction is the X-axis direction. In this case, dummy patterns 7 B are formed on the surfaces of the fixed frame 1 and the frame portion 2 so as to extend in the X-axis direction that is the longitudinal direction of the scanning region 71. That is, the dummy patterns 7B are arranged side by side in the Y-axis direction.

According to the example of FIG. 8, since the pitch d may be designed based on the equations (1) to (4) based on the angle α with respect to the short direction of the scanning region 71, the pitch d of the convex pattern 7 is set. Large design is possible. Therefore, according to this example, the restriction on the pitch d can be relaxed and a wide range of process rules for semiconductor manufacturing can be handled. In the example of FIG. 8, the X-axis direction is an example of the “first direction” in the present invention, and the Y-axis direction is an example of the “second direction” in the present invention.

Similarly, when the scanning region is rectangular, it is preferable that the direction of the concave / convex pattern of the aluminum layer 25 of the sensor unit 20 forming the diffraction grating shown in FIG. 5 and the like is aligned with the longitudinal direction of the scanning range. Thereby, it becomes possible to design the pitch of the uneven pattern in the sensor unit 20 to be large, and it is possible to deal with a wide range of semiconductor manufacturing process rules.

(Modification 2)
The MEMS mirror 100 shown in FIG. 1 is an electromagnetic drive type MEMS mirror having magnets 4A to 4D, but the drive method of the MEMS mirror applicable to the present invention is not limited to this. Instead of this, even in a MEMS mirror that employs other driving methods such as an electrostatic driving method using an electrostatic force acting between electrode plates, a piezoelectric driving method using a deformation force of a piezoelectric material, the present invention is similar to the embodiment. Can be suitably applied.

Even in this case, when forming a wiring pattern for applying a voltage to an electrode plate or a piezoelectric material, the wiring pattern and the dummy pattern are simultaneously formed so as to constitute a diffraction grating. Thereby, the process which reduces the reflected light in the scanning area | region from parts other than a mirror part can be performed cheaply, without adding a new process to the manufacturing process of a MEMS mirror. Similarly, in a MEMS mirror including a sensor unit for detecting displacement of the mirror unit, such as an electrostatic driving method or a piezoelectric driving method using a piezoelectric material deformation force, and diffracting on the surface of the sensor unit. You may make it comprise a grating | lattice.
(Modification 3)
In the example of FIG. 8, the MEMS mirror 100A has the dummy pattern 7B formed so as to extend in the longitudinal direction of the rectangular scanning region 71. Instead, the MEMS mirror 100A is arranged at equal intervals in the X-axis direction and the Y-axis direction. Thus, the concavo-convex dots constituting the diffraction grating may be formed by a dummy pattern. Further, the aluminum layer 25 on the sensor unit 20 described with reference to FIG. 5 may form concave and convex dots constituting a diffraction grating. FIG. 9 shows a front view of the MEMS mirror 100 Aa according to the third modification and an enlarged view of the vicinity of the sensor unit 20. The surfaces of the fixed frame 1 and the frame part 2 in FIG. 9 are concave or convex dots formed at equal intervals in the X-axis direction and the Y-axis direction in regions other than the region where the wiring pattern 7A is formed. A dummy pattern 7Ba is formed. Similarly, dots for forming irregularities are formed in the aluminum layer 25 on the sensor unit 20 at equal intervals in the X-axis direction and the Y-axis direction. By adopting such a configuration, reflection into the scanning range can be suitably reduced regardless of the shape of the scanning region 71.

DESCRIPTION OF SYMBOLS 1 Fixed frame 2 Frame part 3 Mirror part 4A-

4D Magnet

5A, 5B

X-axis torsion bar

6A, 6B Y-axis torsion bar 7 Convex pattern 100 MEMS mirror

Claims

An optical scanner that scans light reflected by the mirror unit in a predetermined angular range by swinging a mirror unit that reflects incident light,
A drive unit coupled to the mirror unit and configured to swing the mirror unit;
A support part for supporting the drive part in a displaceable manner;
Formed on the surface of the drive unit or the support unit on the incident light incident side, the incident light incident on the surface is reflected, and first-order diffracted light due to the reflection is generated outside the predetermined angle range. A reflective diffraction grating,
An optical scanner comprising:
A wiring pattern for supplying electric energy for swinging the mirror unit to the drive unit;
The reflective diffraction grating is formed of the wiring pattern or a dummy pattern that is formed simultaneously with the wiring pattern in a manufacturing process of the wiring pattern and does not have a function of supplying the electric energy. Item 4. The optical scanner according to Item 1.
3. The optical scanner according to claim 1, wherein at least a part of the reflection type diffraction grating is configured by a wiring pattern in which a coil is formed on a surface of the driving unit.
The optical scanner scans the light reflected by the mirror unit on a two-dimensional projection surface,
The reflective diffraction grating is configured by arranging a plurality of dummy patterns extending in a first direction corresponding to a longitudinal direction of a scanning range on the projection surface in a second direction perpendicular to the first direction. The optical scanner according to claim 2.
The drive unit includes a sensor unit that detects swinging of the mirror unit,
The optical scanner according to claim 1, wherein the reflective diffraction grating is formed on a surface of the sensor unit.
The optical scanner according to claim 5, further comprising a metal thin film that shields the incident light on a surface of the reflective diffraction grating.