WO2012014784A1

WO2012014784A1 - Sensor device

Info

Publication number: WO2012014784A1
Application number: PCT/JP2011/066606
Authority: WO
Inventors: 清彦河野; 宏明橘
Original assignee: パナソニック電工株式会社
Priority date: 2010-07-26
Filing date: 2011-07-21
Publication date: 2012-02-02
Also published as: JP2012026935A; TW201210308A

Abstract

This sensor device is so configured as to reflect, by means of an optical mirror, a laser beam for detection to the side of a space to be detected, said laser beam being emitted from a laser device for detection, and to detect, by means of a light detecting unit, the laser beam reflected on the side of the space to be detected. The sensor device includes a half mirror, and the half mirror is disposed such that a part of the laser beam inputted to the half mirror is reflected and the rest is passed through. Between the optical mirror and the half mirror, the optical axis between the laser device and the optical mirror accords with the optical axis between the optical mirror and the light detecting unit.

Description

Sensor device

The present invention relates to a sensor device.

Conventionally, an object recognition sensor having the configuration shown in FIG. 11 has been proposed (Japanese Patent Application Publication No. 6-04398A (hereinafter referred to as “Document 1”)). This object recognition sensor includes a light emitting element 501 that emits a light beam α, a light beam shaping lens 502, an optical scanner 503 that scans the light beam α two-dimensionally, a light receiving element 504, and a scanner drive. A circuit 505 and a signal processing unit 506 are provided.

The above-described light emitting element 501 is constituted by a semiconductor laser element, a light emitting diode, or the like. The light beam shaping lens 502 is provided for condensing or collimating the light beam α emitted from the light emitting element 501.

The optical scanner 503 includes a vibration plate 511 and a piezoelectric element 512. The vibration plate 511 is formed of a silicon thin plate material. A scanning portion 514 is provided at one end of an axial elastic deformation portion (torsion bar) 513 that resonates in a bending deformation mode and a torsional deformation mode, and vibration is generated at the other end. An input unit 515 is provided. On the surface of the scanning unit 514, a mirror surface (not shown) is formed by performing mirror processing. A laminated piezoelectric element 512 is bonded to the vibration input unit 515. Therefore, the vibration plate 511 is supported by the piezoelectric element 512 in the vibration input unit 515, and the scan unit 514 is supported by the elastic deformation unit 513.

Further, the light receiving element 504 is configured by a photodiode or the like.

Further, the scanner driving circuit 505 includes an AC voltage V _B (t) having a frequency equal to the resonance frequency in the bending deformation mode of the elastic deformation portion 513 and an AC voltage V _T (t) having a frequency equal to the resonance frequency in the torsion deformation mode. Is applied to the piezoelectric element 512. Therefore, the elastic deformation portion 513, bending twisting and vibration of the deformation mode performs deformation mode vibration at the same time, rotates the scanning unit 514 in the vertical and horizontal (theta _B direction rotation in FIG. 11 is a vertical direction times dynamic, theta _T direction of rotation is the rotation of the left-right direction). As a result, the optical scanner 503 can continuously scan the light beam α emitted from the light emitting element 501 within the two-dimensional scanning region 507.

In the object recognition sensor described above, since the scanning angle of the light beam α (or the deflection angle of the scanning unit 514) can be known by detecting the voltage V (t) applied to the piezoelectric element 512, the piezoelectric element The voltage values V _B (t) and V _T (t) applied to 512 are output from the scanner driving circuit 505 to the signal processing unit 506 as scanning angle information (or deflection angle information) 510.

In this object recognition sensor, when the object 508 exists in the scanning region 507 of the light beam α, the light beam α emitted from the light emitting element 501 and scanned by the optical scanner 503 is incident on the surface of the object 508 and reflected. The scattered light reflected by the object 508 is received by the light receiving element 504, and the presence of the object 508 is detected. Here, in the object recognition sensor, the light reception signal 509 of the light receiving element 504 is input to the signal processing unit 506. When the signal processing unit 506 receives the light reception signal 509 from the light receiving element 504, the signal processing unit 506 reads the scanning angle information 510 at that moment, converts it into coordinates, and detects the two-dimensional position of the object 508.

Note that Document 1 describes that an object recognition sensor can be used in the fields of a code reader, a human body detection sensor, a two-dimensional photoelectric sensor, and the like.

By the way, in the sensor device such as the object recognition sensor having the configuration shown in FIG. 11, the optical axis of the optical system including the light emitting element 501, the lens 502, and the optical scanner 503 is different from the optical axis of the light receiving element 504. Therefore, the light receiving element 504 is easily affected by disturbance light, and the entire sensor device is increased in size.

The present invention has been made in view of the above-described reasons, and an object thereof is to provide a sensor device that is not easily affected by ambient light and can be miniaturized.

The sensor device of the present invention includes a detection laser configured to emit detection laser light, an optical mirror configured to reflect the detection laser light toward the detection target space, and the detection target space. And a light detection unit configured to detect the detection laser light reflected on the side. The sensor device further includes a half mirror, which is disposed so as to reflect and transmit a part and the remaining part of the detection laser light incident on the half mirror. The said optical mirror consists of a MEMS device provided with a movable part and the mirror surface provided in this movable part. The optical mirror reflects the detection laser light from the half mirror to the detection target space side by the mirror surface, and the detection laser light reflected from the detection target space side by the mirror surface. It arrange | positions so that it may reflect in the said photon detection part side. The optical axis between the detection laser and the optical mirror and the optical axis between the optical mirror and the light detection unit are matched between the optical mirror and the half mirror.

In one embodiment, the sensor device further includes a determination unit configured to determine the presence or absence of an object in the detection target space based on the output of the light detection unit.

In one embodiment, the half mirror has the detection in which a part of the detection laser light emitted from the detection laser is reflected by the half mirror to the optical mirror and reflected by the detection target space side. It arrange | positions so that some laser beams may pass through this half mirror and may inject into the said photon detection part.

In one embodiment, the sensor device includes a display unit disposed in the detection target space, a display laser configured to emit display laser light for performing predetermined display on the display unit, And a dichroic mirror positioned between the detection laser and the half mirror. The dichroic mirror is configured so that the display laser light emitted from the display laser is reflected by the dichroic mirror toward the half mirror and the detection laser light from the detection laser is transmitted through the dichroic mirror. Composed.

In one embodiment, the sensor device further includes a lens positioned between the half mirror and the light detection unit for condensing the detection laser light on a light receiving surface of the light detection unit. Further, the lens is arranged at a position where an image forming relationship is established with respect to the display unit.

In one embodiment, the display unit includes a screen that retroreflects both the detection laser beam and the display laser beam.

In one embodiment, the sensor device further includes a light shielding member that is disposed around an optical path of the detection laser light and the display laser light and blocks stray light.

In one embodiment, the sensor device includes a housing that houses the detection laser, the half mirror, the optical mirror, the light detection unit, the display laser, the dichroic mirror, the lens, and the light shielding member. In addition. The inner surface of the housing is a rough surface that scatters the stray light.

In the sensor device of the present invention, it is difficult to be influenced by disturbance light and can be miniaturized.

Preferred embodiments of the invention are described in further detail. Other features and advantages of the present invention will be better understood with reference to the following detailed description and accompanying drawings.
FIG. 1A is a schematic configuration diagram, and FIGS. 1B to 1D are operation explanatory diagrams illustrating a sensor device according to an embodiment of the present invention. It is a principal part schematic perspective view of a sensor apparatus same as the above. It is a general | schematic disassembled perspective view of the optical mirror in a sensor apparatus same as the above. It is a schematic perspective view of the optical mirror in a sensor apparatus same as the above. It is principal process sectional drawing for demonstrating the manufacturing method of the optical mirror in a sensor apparatus same as the above. 6A and 6B are explanatory views of the operation of the above sensor device. It is a principal part schematic plan view of a sensor apparatus same as the above. 8A to 8C are explanatory views of the assembly method of the sensor device. 9A and 9B are explanatory diagrams of application examples of the sensor device. It is a schematic block diagram which shows the other structural example of a sensor apparatus same as the above. It is a schematic block diagram of the object recognition sensor of a prior art example.

Hereinafter, the sensor device of the present embodiment will be described with reference to FIGS. The sensor device includes a detection laser 401 configured to emit a detection laser beam LB1, a MEMS mirror 403 configured to reflect the detection laser beam LB1 toward the detection target space 405, and a detection target space. And a light detection unit (light receiving unit) 404 configured to detect (receive light) the detection laser beam LB1 reflected on the 405 side. The sensor device further includes a half mirror (beam splitter) 402, which includes a part (typically half) and a remainder (typically another half) of the detection laser light LB1 incident on the half mirror 402. They are arranged to reflect and transmit, respectively. 1A to 1D, the half mirror 402 reflects a part of the detection laser beam LB1 emitted from the detection laser 401 to the optical mirror 403 by the half mirror 402 (more specifically, only the half mirror 402), and A part of the detection laser beam LB1 reflected on the detection target space 405 side is disposed so as to pass through the half mirror 402 and enter the light detection unit 404. The MEMS mirror 403 is a MEMS (micro electro mechanical systems) device, which includes a movable part 20 (see FIGS. 3, 4 and 5F) and a mirror surface 21 provided on the movable part 20 (FIG. 3, FIG. 5F). The MEMS mirror 403 reflects the detection laser beam LB1 from the half mirror 402 to the detection target space 405 side by the mirror surface 21, and at least the detection laser beam LB1 reflected from the detection target space 405 side. 21 is arranged so as to be reflected toward the light detection unit 404 side. In FIGS. 1A to 1D, the MEMS mirror 403 reflects the detection laser beam LB1 reflected by the half mirror 402 to the detection target space 405 side by the mirror surface 21, and also detects an object in the detection target space 405 (shown in FIG. 1). In this example, the detection laser beam LB1 reflected by the finger 406 or the display unit 410 described later is arranged to be reflected by the mirror surface 21 (specifically, only by the mirror surface 21) toward the light detection unit 404. . The light detection unit 404 is located on the opposite side of the MEMS mirror 403 with the half mirror 402 interposed therebetween. Therefore, the light detection unit 404 detects the detection laser light LB1 reflected by the MEMS mirror 403 after being reflected by the object 406 or the display unit 410 in the detection target space 405. The sensor device optionally further includes a determination unit 408 configured to determine the presence or absence of the object 406 in the detection target space 405 based on the output of the light detection unit 404. Here, the light detection unit 404 detects the detection laser light LB1 transmitted through the half mirror 402. In the present embodiment, the MEMS mirror 403 constitutes an optical mirror.

By the way, the sensor device includes an optical axis OA1 between the detection laser 401 and the MEMS mirror 403, an optical axis OA2 between the MEMS mirror 403 and the light detection unit 404, and a gap between the MEMS mirror 403 and the half mirror 402. Are matched.

The sensor device includes a display unit 410 disposed in the detection target space 405, a display laser 411 configured to emit display laser light LB2 for performing predetermined display on the display unit 410, A dichroic mirror 412 positioned between the detection laser LB1 and the half mirror 402 is provided. The dichroic mirror 412 reflects the display laser beam LB2 emitted from the display laser 411 to the half mirror 402 side by the dichroic mirror 412, and transmits the detection laser beam LB1 from the detection laser 401 through the dichroic mirror 412. It is optically designed.

Further, the half mirror 402 is optically designed to transmit part of the detection laser beam LB1 and reflect the rest. Therefore, the half mirror 402 has a function of reflecting the detection laser beam LB1 emitted from the detection laser 401 to the MEMS mirror 403 side, and is reflected by the object 406 or the display unit 410 in the detection target space 405 and further the MEMS mirror 403. The optical design is such that it has a function of transmitting the detection laser beam LB1 reflected by. The half mirror 402 is optically designed to reflect the display laser beam LB2 from the display laser 411 in a predetermined direction (on the MEMS mirror 403 side). In short, the half mirror 402 is provided with a semi-transmissive layer that reflects part of the detection laser beam LB1 and transmits the remaining part on the MEMS mirror 403 side, and this semi-transmissive layer reflects the display laser beam LB2. It also serves as a wavelength selection layer.

As the detection laser 401, a first semiconductor laser that emits infrared light is used as the detection laser light LB1. The display laser 411 uses a second semiconductor laser that emits red light as the display laser beam LB2.

1B indicates the travel path of the detection laser beam LB1 emitted from the detection laser 401 to the detection target space 405, and the solid line arrow in FIG. 1C is reflected by the display unit 410. The traveling path of the detected laser LB1 is shown, and the solid line arrow in FIG. 1D shows the traveling path to the display unit 410 of the display laser beam LB2 emitted from the display laser 411.

Thus, in the sensor device, the display laser 411 can be easily blinked and dimmed by turning on and off the second power supply for supplying power to the display laser 411 and controlling the duty ratio, and the display unit 410 can be controlled in a predetermined manner. (For example, an image of a virtual switch 440 as shown in FIG. 9) can be displayed. In the sensor device, since the half mirror 402 is shared by the optical system for displaying an image on the display unit 410 and the optical system for detecting the object 406, the number of components can be reduced, and the size and weight can be reduced. Can be achieved.

The light detection unit 404 is a photodiode having sensitivity to infrared light, and its output changes according to the amount of received light. Therefore, in the sensor device, the reflectance of the reflecting surface on which the detection laser beam LB1 is reflected in the detection target space 405 changes depending on the presence / absence of the object 406 on the optical path of the detection laser beam LB1, so that the light The amount of light received by the detection unit 404 changes. That is, when the object 406 does not exist on the optical path of the detection laser beam LB1 in the detection target space 405, the reflectance of the reflection surface is determined by the display unit 410, but the detection laser beam LB1 light in the detection target space 405 When there is an object 406 on the road, the reflectance of the reflecting surface is determined by the object 406, so the amount of light received by the light detection unit 404 changes according to the difference in reflectance of the reflecting surface.

Also, the sensor device includes a lens 407 positioned between the half mirror 402 and the light detection unit 404. Here, the lens 407 condenses the detection laser beam LB1 transmitted through the half mirror 402 on the light receiving surface 404a of the light detection unit 404.

The lens 407 is a biconvex lens, and is disposed at a position that is in an imaging relationship with the display unit 410. In short, as shown in FIG. 6A, when the object 406 is not present on the optical path of the detection laser beam LB1, the lens 407 has an imaging surface in the direction of the optical axis of the light detection unit 404. The spot diameter of the detection laser beam LB1 is the minimum spot diameter at the position of the light receiving surface 404a of the light detection unit 404. Therefore, as shown in FIG. 6B, when the object 406 is present on the optical path of the detection laser beam LB1, the position of the imaging plane is shifted in the direction of the optical axis of the light detection unit 404. As a result, the image 414 (see FIG. 6C) of the detection laser beam LB1 in the light detection unit 404 spreads (so-called image height changes, in other words, blur occurs without being in focus). It is possible to increase the change in the amount of light received by the light detection unit 404 due to the above. For example, assuming that the diameter of the light receiving surface 404a of the light detection unit 404 is 1 mm, and the image height is 1 mm when the object 406 is not present on the optical path of the detection laser beam LB1 as shown in FIG. Further, if the image height is 2 mm when the object 406 is present on the optical path of the detection laser beam LB1, the amount of light received by the light detection unit 404 is drastically reduced. Therefore, even when the difference between the reflectance of the object 406 and the reflectance of the display unit 410 is relatively small, the change in the amount of received light due to the presence or absence of the object 406 increases.

By the way, as the display unit 410, a screen whose reflected light intensity of the detection laser beam LB1 follows Lambert's cosine law (that is, a screen on which the display unit 410 Lambert reflects the detection laser beam LB1) is used. In the case where the object 406 is not present, the amount of light received by the light detection unit 404 is small, and the change in the amount of light received by the light detection unit 404 due to the presence or absence of the object 406 is small, so the S / N ratio is small.

Therefore, the display unit 410 is preferably composed of a screen that retroreflects the detection laser beam LB1. In short, it is preferable to use a so-called retroreflective screen as the screen constituting the display unit 410. The retroreflective screen is a screen that emits reflected light in the same direction as incident light, and has high reflection directivity. Therefore, if a retroreflective screen is used as the display unit 410, the amount of light received by the light detection unit 404 in the absence of the object 406 can be increased, and the change in the amount of light received by the light detection unit 404 depending on the presence or absence of the object 406. Can be increased, and the S / N ratio can be increased. Thereby, in the sensor device, the S / N ratio of the output of the light detection unit 404 can be improved, and the detection accuracy of the object 406 can be improved.

As a retroreflector used for a retroreflective screen, etc., a reflection sheet in which glass beads for refracting light are two-dimensionally arranged, and a reflection in which prism lenses for refracting light are two-dimensionally arranged are used. Sheets and the like are known (for example, see http://www.kokusaku.com/3M.htm for this type of reflective sheet).

As shown in FIGS. 3, 4, and 5 F, the MEMS mirror 403 is formed using a SOI (Silicon on ulator Insulator) substrate 100 that is a semiconductor substrate, and the mirror forming substrate 1 in which the mirror surface 21 is provided on the movable portion 20. It has. Further, the MEMS mirror 403 includes a first cover substrate 2 bonded to one surface (first surface) side where the mirror surface 21 is provided in the mirror forming substrate 1. The MEMS mirror 403 includes a second cover substrate 3 bonded to the other surface (second surface) side of the mirror forming substrate 1.

The mirror forming substrate 1 is formed by processing the above-described SOI substrate 100 by a bulk micromachining technique or the like. In this SOI substrate 100, an insulating layer (SiO2 layer) 100c is interposed between a conductive first silicon layer (active layer) 100a and a second silicon layer (silicon substrate) 100b. In the SOI substrate 100, the thickness of the first silicon layer 100a is set to 30 μm, and the thickness of the second silicon layer 100b is set to 400 μm. However, these numerical values are examples, and are not particularly limited. Absent. The surface of the first silicon layer 10a, which is one surface (first surface) of the SOI substrate 100, is the (100) surface.

The mirror forming substrate 1 includes an outer frame portion 10, the above-described movable portion 20 disposed inside the outer frame portion 10, and an outer frame portion 10 disposed so as to sandwich the movable portion 20 inside the outer frame portion 10. A pair of first

torsion spring portions

30 and 30 connected to the movable portion 20 are provided. Each of the first

torsion spring portions

30 and 30 can be torsionally deformed.

The outer frame portion 10 has a frame shape (here, a rectangular frame shape), and each of an outer peripheral shape and an inner peripheral shape is formed in a rectangular shape. Here, in the MEMS mirror, the outer peripheral shape of each of the mirror forming substrate 1 and each of the

cover substrates

2 and 3 is rectangular, and the outer dimensions of each of the

cover substrates

2 and 3 are matched with the outer dimensions of the mirror forming substrate 1. is there.

The first cover substrate 2 is formed by using a first glass substrate 200 formed by stacking and joining two glass plates each made of Pyrex (registered trademark) glass in the thickness direction. . The second cover substrate 3 is formed using a second glass substrate 300 made of Pyrex (registered trademark) glass or the like. Note that the thicknesses of the first glass substrate 200 and the second glass substrate 300 are set in the range of about 0.5 mm to 1.5 mm, but these numerical values are examples and are not particularly limited. Absent.

The outer frame portion 10 of the mirror forming substrate 1 is formed using the first silicon layer 100a, the insulating layer 100c, and the second silicon layer 100b of the SOI substrate 100, respectively. In the mirror forming substrate 1, a portion of the outer frame portion 10 formed by the first silicon layer 100 a is joined to the outer peripheral portion of the first cover substrate 2 over the entire periphery. Of these, the portion formed by the second silicon layer 100 b is bonded to the outer periphery of the second cover substrate 3 over the entire periphery.

Further, the movable portion 20 and the

torsion spring portions

30, 30 of the mirror forming substrate 1 are formed using the first silicon layer 100 a of the SOI substrate 100 and are sufficiently thinner than the outer frame portion 10. Yes. The mirror surface 21 provided on the movable unit 20 reflects the detection laser beam LB1 from the detection laser 401 and the display laser beam LB2 from the display laser 411. The reflective film 21a is made of a second metal film (for example, an Al—Si film) formed on a portion formed by the silicon layer 100a. In the present embodiment, the thickness of the reflective film 21a is set to 500 nm, but this numerical value is an example and is not particularly limited.

In the following, as shown on the left side of FIG. 3, the direction orthogonal to the juxtaposed direction of the pair of first

torsion spring portions

30, 30 in plan view is the x-axis direction (first direction), and the pair of first torsion The parallel arrangement direction of the

spring portions

30 and 30 will be described as the y-axis direction (second direction), and the direction orthogonal to the x-axis direction and the y-axis direction will be described as the z-axis direction (third direction).

In the mirror forming substrate 1, a pair of first

torsion spring portions

30, 30 are arranged in parallel in the y-axis direction, and the movable portion 20 is a pair of first

torsion spring portions

30, 30 with respect to the outer frame portion 10. It can be displaced around 30 (it can be rotated around an axis in the y-axis direction). That is, the pair of first

torsion spring portions

30, 30 connects the outer frame portion 10 and the movable portion 20 so that the movable portion 20 can swing with respect to the outer frame portion 10. In other words, the movable part 20 disposed inside the outer frame part 10 is connected to the outer frame via two first

torsion spring parts

30 and 30 that are continuously and integrally extended in two opposite directions from the movable part 20. The part 10 is supported so as to be swingable. Here, the pair of first

torsion spring portions

30 and 30 are formed such that a straight line connecting the center lines along the y-axis direction passes through the center of gravity of the movable portion 20 in plan view. Each of the

torsion spring portions

30 and 30 has a thickness dimension (dimension in the z-axis direction) set to 30 μm and a width dimension (dimension in the x-axis direction) set to 5 μm, but these numerical values are examples. There is no particular limitation. Further, the inner peripheral shape of the outer frame portion 10 is not limited to a rectangular shape, and may be a circular shape, for example.

The mirror forming substrate 1 described above is perpendicular to the direction in which the pair of first

torsion spring portions

30 and 30 are connected in the movable portion 20 (the direction in which the pair of first

torsion spring portions

30 and 30 are juxtaposed) (that is, Comb-shaped first movable electrodes 22 are formed on both sides in the x-axis direction). Further, the mirror forming substrate 1 includes comb-shaped first fixed

electrodes

12 and 12, which are formed on the outer frame portion 10 so as to face (adjacent) the first

movable electrodes

22 and 22, respectively. Has been. Each first fixed electrode 12 has a plurality of fixed comb teeth 12b facing (adjacent) to the plurality of movable comb teeth 22b of the first movable electrode 22 facing each other. Here, the first

movable electrodes

22 and 22 and the first

fixed electrodes

12 and 12 constitute an electrostatic drive type first driving means for driving the movable portion 20 by electrostatic force. In the present embodiment, the first driving means drives the movable portion 20 by electrostatic force, but is not limited to an electrostatic drive type, and for example, an electromagnetic drive type that drives the movable portion 20 by an electromagnetic force. Alternatively, a piezoelectric drive type in which the movable portion 20 is driven by a piezoelectric element may be used.

The first fixed electrode 12 has a comb shape in plan view, and a portion of the outer frame portion 10 formed by the first silicon layer 100a in the frame piece portion along the y-axis direction is comb-shaped. The bone part 12a is comprised. The first fixed electrode 12 has a pair of fixed comb teeth 12b on the surface facing the movable portion 20 in the comb bone portion 12a (inner side surface along the y-axis direction in the outer frame portion 10). The torsion spring portions 30 are arranged in a line along the direction in which the

torsion spring portions

30 and 30 are juxtaposed. Here, each fixed comb tooth piece 12b is constituted by a part of the first silicon layer 100a.

On the other hand, the first movable electrode 22 is a fixed comb on the side surface (side surface along the y-axis direction in the movable portion 20) of the comb portion 12 a on the comb bone portion 12 a side of the first fixed electrode 12 in the movable portion 20. A large number of movable comb teeth 22b respectively facing the teeth 12b are arranged in the parallel direction. Here, each movable comb-tooth piece 22b is constituted by a part of the first silicon layer 100a.

In the first fixed electrode 12 and the first movable electrode 22, the

comb bone portions

12 a and 22 a face each other, and each fixed comb tooth piece 12 b of the first fixed electrode 12 corresponds to the first movable electrode 22. The comb grooves (between adjacent

movable comb teeth

22b, 22b) are arranged, and the fixed comb teeth 12b and the movable comb teeth 22b are separated from each other in the y-axis direction. Therefore, in the first driving means, a voltage is applied between the first fixed electrode 12 and the first movable electrode 22, so that the gap between the first fixed electrode 12 and the first movable electrode 22 is applied. An electrostatic force acting in a direction attracting each other is generated. The gap between the fixed comb tooth piece 12b and the movable comb tooth piece 22b in the y-axis direction may be set as appropriate within a range of, for example, about 2 μm to 5 μm.

By the way, the movable part 20 includes a frame-like (here, rectangular frame-like) movable frame part 23 supported by the outer frame part 10 through a pair of first

torsion spring parts

30 and 30 in a swingable manner, A mirror part 24 provided inside the movable frame part 23 and provided with a mirror surface 21 and a mirror part 24 arranged inside the movable frame part 23 so as to sandwich the mirror part 24 are connected and twisted. It has a pair of 2nd

torsion spring parts

25 and 25 which can be changed.

The second torsion springs 25 and 25 are juxtaposed in a direction (x-axis direction) orthogonal to the juxtaposition direction (y-axis direction) of the first torsion springs 30 and 30. In short, the movable portion 20 has a pair of second

torsion spring portions

25, 25 arranged in parallel in the x-axis direction, and the mirror portion 24 is a pair of second torsion spring portions 25 with respect to the movable frame portion 23. , 25 (displaceable around the axis in the x-axis direction). That is, the pair of second

torsion spring portions

25, 25 connect the movable frame portion 23 and the mirror portion 24 so that the mirror portion 24 can swing with respect to the movable frame portion 23. In other words, the mirror part 24 disposed inside the movable frame part 23 is movable frame part via two second

torsion spring parts

25, 25 extended continuously and integrally from the mirror part 24 in two opposite directions. 23 is swingably supported. Here, the pair of second

torsion spring portions

25 and 25 are formed such that a straight line connecting the center lines along the x-axis direction passes through the center of gravity of the mirror portion 24 in plan view. Each second torsion spring portion 25 has a thickness dimension (dimension in the z-axis direction) set to 30 μm and a width dimension (dimension in the y-axis direction) set to 30 μm. However, these numerical values are only examples. There is no particular limitation. Moreover, the planar view shape of the mirror part 24 and the mirror surface 21 is not restricted to a rectangular shape, For example, a circular shape may be sufficient. Further, the inner peripheral shape of the movable frame portion 23 is not limited to a rectangular shape, and may be a circular shape, for example.

As can be seen from the above description, the mirror portion 24 is configured to rotate around the axis of the pair of first

torsion spring portions

30 and 30 and rotate around the axis of the pair of second

torsion spring portions

25 and 25. Is possible. In short, the MEMS mirror 403 is configured such that the mirror surface 21 of the mirror section 24 is two-dimensionally rotatable, and can scan the detection laser beam LB1 and the display laser beam LB2 two-dimensionally. . Here, the movable portion 20 is integrally provided with a frame-shaped (rectangular frame-shaped) support body 29 that supports the movable frame portion 23 on the opposite side of the movable frame portion 23 to the first cover substrate 2 side. The support 29 can be rotated integrally with the movable frame portion 23.

Further, the mirror forming substrate 1 is perpendicular to the direction connecting the pair of second

torsion spring portions

25, 25 in the mirror portion 24 (ie, the direction in which the pair of second

torsion spring portions

25, 25 are juxtaposed) (that is, Comb-shaped second

movable electrodes

27, 27 formed on both sides in the y-axis direction) and comb-shaped second fixed

electrodes

26, 26 are provided. The second

fixed electrodes

26 and 26 are formed on the movable frame portion 23 so as to face (adjacent) the second

movable electrodes

27 and 27, respectively. Each of the second fixed electrodes 26 has a plurality of fixed comb teeth pieces 26b that face (adjacent) each of the plurality of movable comb teeth pieces 27b of the second movable electrode 27 facing each other. The second

movable electrodes

27, 27 and the second

fixed electrodes

26, 26 constitute an electrostatically driven second driving means for driving the mirror portion 24 by electrostatic force.

The above-described second fixed electrode 26 has a comb shape in plan view, and the comb bone portion 26a is constituted by a part of the movable frame portion 23. A large number of fixed comb teeth pieces 26b are formed on a surface facing the mirror portion 24 of the comb portion 26a of the second fixed electrode 26 (an inner surface along the x-axis direction of the movable frame portion 23). The second torsion spring portions 25 are arranged in a line along the direction in which the second

torsion spring portions

25 and 25 are juxtaposed. On the other hand, the second movable electrode 27 is configured by a part of the mirror portion 24, and the side surface of the second fixed electrode 26 on the side of the comb portion 26 a (the side surface along the x-axis direction in the mirror portion 24) A large number of movable comb teeth 27b facing the fixed comb teeth 26b are arranged in the parallel direction. Here, in the comb-shaped second fixed electrode 26 and the comb-shaped second movable electrode 27, the

comb bone portions

26a and 27a are opposed to each other, and each fixed comb tooth piece 26b of the second fixed electrode 26 is The second movable electrode 27 is inserted into a comb groove (between adjacent movable comb teeth 27b), and the fixed comb teeth 26b and the movable comb teeth 27b are separated from each other in the x-axis direction. Therefore, the mirror forming substrate 1 is applied between the second fixed electrode 26 and the second movable electrode 27 by applying a voltage between the second fixed electrode 26 and the second movable electrode 22. Electrostatic forces acting in the direction of attracting each other are generated. In addition, the gap between the fixed comb tooth piece 26b and the movable comb tooth piece 27b in the x-axis direction may be set as appropriate within a range of about 2 μm to 5 μm, for example.

Further, the mirror forming substrate 1 is arranged in parallel at substantially equal intervals on the outer frame portion 10 so that the three pads 13 are arranged in a straight line in a plan view. On the other hand, the first cover substrate 2 is provided with three through holes 202 that expose the pads 13 separately. Each pad 13 has a circular shape in plan view, and is composed of a first metal film (for example, an Al—Si film). In this embodiment, the film thickness of each pad 13 is set to 500 nm, but this numerical value is an example and is not particularly limited.

The mirror forming substrate 1 is formed with a plurality of (here, three) slits 10 a in the portion formed by the first silicon layer 100 a in the outer frame portion 10, and the first in the movable frame portion 23 of the movable portion 20. A plurality of (here, four) slits 20a are formed in a portion formed by the silicon layer 100a. Thereby, in the mirror forming substrate 1, the middle pad 13 (13b) in FIG. 3 among the three pads 13 is electrically connected to the first fixed electrode 12 to have the same potential, and the right pad 13 (13a). Are electrically connected to the first movable electrode 22 and the second movable electrode 26 to have the same potential, and the left pad 13 (13c) is electrically connected to the second movable electrode 27 of the mirror portion 24. The potential is the same.

Here, the plurality of slits 10a of the outer frame portion 10 are formed with a depth reaching the insulating layer 100c. The MEMS mirror 403 according to the present embodiment forms the slits 10a in the outer frame portion 10 by using the slits 10a as trenches and making the shape of each slit 10a in plan view not open to the outer surface side of the outer frame portion 10. While adopting the above structure, it is possible to prevent the bonding property between the outer frame portion 10 and the first cover substrate 2 from being lowered, and the airtightness of the space surrounded by the outer frame portion 10 and the

respective cover substrates

2 and 3 Is secured.

In addition, each slit 20a of the movable frame portion 23 in the movable portion 20 is a trench, and the above-described support 29 is configured by a part of the insulating layer 100c of the SOI substrate 100 and a part of the second silicon layer 100b. The depth reaches the insulating layer 100c. In short, the MEMS mirror 403 employs a configuration in which the movable frame portion 23 is formed with a plurality of slits 20a, but the movable frame portion 23 and the support 29 are the shafts of the pair of first

torsion spring portions

30 and 30. It is possible to rotate integrally around. Here, the support 29 is formed in a frame shape that covers a portion of the movable frame portion 23 excluding each fixed comb tooth piece 26b and each movable comb tooth piece 22b (see FIG. 4). In addition, the plurality of trenches 20a of the movable frame portion 23 has the center of gravity of the movable portion 20 including the support 29 centered along the y-axis direction of the pair of first

torsion spring portions

30 and 30 in plan view. The shape is designed so that it is located approximately in the middle of the connecting straight line. Therefore, in the MEMS mirror 403 in the present embodiment, the movable portion 20 smoothly swings around the axis of the pair of first

torsion spring portions

30 and 30, and the reflected light is appropriately scanned. In the present embodiment, the thickness of the portion constituted by the second silicon layer 100b in the support 29 is set to the same thickness as the portion constituted by the second silicon layer 100b in the outer frame portion 10. However, it is not limited to the same, and may be thicker or thinner.

The first cover substrate 2 uses the first glass substrate 200 as described above, and penetrates in the thickness direction of the first glass substrate 200 to expose each pad 13 over the entire circumference. A through hole 202 is formed. Here, each through hole 202 of the first glass substrate 200 is formed in a tapered shape in which the opening area gradually increases as the distance from the mirror forming substrate 1 increases. Each through-hole 202 is formed by sandblasting. The method of forming each through-hole 202 is not limited to the sand blast method, and a drilling method, an etching method, or the like may be employed.

The MEMS mirror 403 has a circular shape in plan view of each pad 13 so that the opening diameter of each through-hole 202 on the first mirror forming substrate 1 side is larger than the diameter of each pad 13. is there. The diameter of each pad 13 is set to 0.5 mm, but is not particularly limited. Further, the planar view shape of each pad 13 is not necessarily a circular shape, and may be a square shape, for example, but in order to reduce the opening diameter of each through hole 202, the circular shape is more preferable than the square shape. preferable.

By the way, when a part of each pad 13 overlaps with the first cover substrate 2 in the thickness direction, the bondability and airtightness are impaired by the influence of the thickness of each pad 13, and the yield during manufacture is reduced and the operation is stable. There is concern that it may cause a decrease in stability and stability over time. Therefore, in such a case, it is necessary to increase the width dimension of the outer frame portion 10 (the distance between the outer surface and the inner surface of the outer frame portion 10), and the size reduction of the MEMS mirror 403 is limited. It is possible.

On the other hand, in the MEMS mirror 403 in the present embodiment, the first cover substrate 2 does not overlap each pad 13, and one pad 13 is provided between the first cover substrate 2 and the outer frame portion 10. There is no intervening part. Therefore, in the MEMS mirror 403, it is possible to prevent the bonding between the first cover substrate 2 and the outer frame portion 10 of the mirror forming substrate 1 from being hindered by each pad 13. As a result, in the MEMS mirror 403, it is possible to prevent the bondability and airtightness from being affected by the thickness of each pad 13, and to reduce the cost by improving the yield without increasing the width dimension of the outer frame portion 10. It is possible to reduce the operational stability and the temporal stability.

In the MEMS mirror 403, the airtight space surrounded by the outer frame portion 10 of the mirror forming substrate 1 and each of the

cover substrates

2 and 3 is made a vacuum (vacuum atmosphere), so that the movable portion 20 can be reduced while reducing power consumption. In addition, the mechanical deflection angle of the mirror unit 24 can be increased. Therefore, in the MEMS mirror 403, the airtight space is evacuated and non-evaporated to an appropriate portion inside the portion of the second cover substrate 3 facing the mirror forming substrate 1 that is bonded to the outer frame portion 10. A mold getter (not shown) is provided. The non-evaporable getter may be formed of, for example, an alloy containing Zr as a main component or an alloy containing Ti as a main component. In the MEMS mirror 403, the airtight space surrounded by the outer frame portion 10, the first cover substrate 2, and the second cover substrate 3 may be an inert gas atmosphere (for example, a dry nitrogen gas atmosphere). Good. In the MEMS mirror 403 described above, the mirror surface 21 can be prevented from being oxidized regardless of whether the airtight space is a vacuum atmosphere or an inert gas atmosphere. It is possible to suppress the change with time of the reflection characteristics.

The first glass substrate 200 has a first recess 201 for securing a displacement space of the movable portion 20 on the surface facing the mirror forming substrate 1. Here, the first glass substrate 200 is formed by joining two glass plates as described above. Therefore, the first glass substrate 200 penetrates in a thickness direction in a portion corresponding to the first recess 201 in a glass plate (hereinafter referred to as a first glass plate) disposed on the side close to the mirror forming substrate 1. A glass plate (hereinafter referred to as a second glass plate) that forms the aperture and is disposed on the side far from the mirror-forming substrate 1 has a flat plate shape. Therefore, the first glass substrate 200 can have a smooth surface on the inner bottom surface of the first recess 201 as compared with the case where the first recess 201 is formed by sandblasting or the like. Diffuse reflection, light diffusion, scattering loss, and the like on the inner bottom surface of 201 can be reduced.

Further, the second cover substrate 3 has a second recess 301 for securing a displacement space of the movable portion 20 on the one surface of the second glass substrate 300 on the mirror forming substrate 1 side.

Here, when the concave portion 301 is formed on the one surface (first surface) of the second glass substrate 300, for example, it may be formed by a sandblast method or the like. Similarly to the first cover substrate 2, the second cover substrate 3 may be formed by joining two glass plates. A glass plate (hereinafter referred to as a glass plate disposed on the side close to the mirror forming substrate 1). A glass plate (hereinafter referred to as a fourth glass plate) disposed on the side far from the mirror forming substrate 1 while forming an opening portion penetrating in the thickness direction at a portion corresponding to the second recess 301 in the third glass plate). (Referred to as a glass plate) may be flat. Since the second cover substrate 3 does not need to transmit light, the second cover substrate 3 is not limited to the second glass substrate 300 but can be easily bonded to the mirror forming substrate 1 and is made of a material of the semiconductor substrate (SOI substrate 100). A substrate formed of a material having a small difference in linear expansion coefficient from Si may be used. For example, the substrate may be formed using a silicon substrate. In this case, the second recess 301 is formed by a photolithography technique and an etching technique. What is necessary is just to form using.

Further, in the MEMS mirror 403 according to the present embodiment, the airtight space surrounded by the outer frame portion 10, the first cover substrate 2 and the second cover substrate 3 is evacuated so that the power consumption can be reduced. Since the mechanical deflection angle of the portion 20 can be increased, the airtight space is evacuated and the getter described above is disposed on the inner bottom surface of the second recess 301.

In the present embodiment, the thicknesses of the first cover substrate 2 and the second cover substrate 3 are set in a range of about 0.5 mm to 1.5 mm, and the first recess 201 and the second recess 301 are formed. Although the depth is set in the range of 300 μm to 800 μm, these numerical values are merely examples, and may be set appropriately according to the amount of displacement of the movable part 20 in the z-axis direction (that is, the rotation of the movable part 20). The depth is not particularly limited as long as the depth does not hinder dynamic movement.

Pyrex (registered trademark), which is a borosilicate glass, is adopted as the glass material of each

glass substrate

200, 300, but is not limited to a borosilicate glass, for example, soda lime glass, non-alkali glass, quartz glass, etc. It may be adopted.

Hereinafter, a method of manufacturing the MEMS mirror 403 will be described with reference to FIG. 5. FIGS. 5A to 5F show schematic cross sections of a portion corresponding to the cross section AB of FIG.

First, an oxide film forming step of forming

silicon oxide films

111a and 111b on the one surface (first surface) side and the other surface (second surface) side of the SOI substrate 100, which is a semiconductor substrate, by thermal oxidation or the like. By doing so, the structure shown in FIG. 5A is obtained.

Thereafter, a first silicon oxide patterning the silicon oxide film (hereinafter referred to as the first silicon oxide film) 111a on the one surface (first surface) side of the SOI substrate 100 using photolithography technology and etching technology. By performing the film patterning step, the structure shown in FIG. 5B is obtained. This first silicon oxide film patterning step corresponds to a portion of the first silicon oxide film 111a other than the region where the reflective film 21a is to be formed in the movable portion 20, the first

torsion spring portions

30, 30 and the like. The first silicon oxide film 111a is patterned so that a part or the like remains.

After the first silicon oxide film patterning step, a metal film (for example, Al—Si film) having a predetermined film thickness (for example, 500 nm) is formed on the one surface (first surface) side of the SOI substrate 100 by sputtering or vapor deposition. 5C by performing a metal film patterning process for forming each pad 13 and the reflective film 21a by patterning the metal film using a photolithography technique and an etching technique. The structure shown in is obtained. In this embodiment, since the material and film thickness of each pad 13 and the reflective film 21a are set to be the same, each pad 13 and the reflective film 21a are formed simultaneously. When the material and film thickness of the film 21a are different, the pad forming process for forming each pad 13 and the reflective film forming process for forming the reflective film 21a may be provided separately.

After forming each of the pads 13 and the reflective film 21a, the movable frame portion 23, the mirror portion 24, and the pair of first first layers of the first silicon layer 100a are formed on the one surface (first surface) side of the SOI substrate 100.

Torsion spring portions

30, 30, a pair of second

torsion spring portions

25, 25, outer frame portion 10, first fixed electrode 12, second movable electrode 22, second fixed electrode 26, second movable. A first resist layer 130 patterned so as to cover a portion corresponding to the electrode 27 is formed. After that, using the first resist layer 130 as a mask, the first silicon layer 100a is patterned by etching the first silicon layer 100a to a depth (first predetermined depth) reaching the insulating layer 100c. The structure shown in FIG. 5D is obtained by performing the silicon layer patterning step (surface side patterning step). Etching of the first silicon layer 100a in the first silicon layer patterning step may be performed by a dry etching apparatus capable of highly anisotropic etching, such as an inductively coupled plasma etching apparatus. In the first silicon layer patterning step, the insulating layer 100c is used as an etching stopper layer.

After the above-described first silicon layer patterning step, the first resist layer 130 on the one surface (first surface) side of the SOI substrate 100 is removed. Thereafter, a second resist layer 131 is formed on the entire surface of the SOI substrate 100 on the one surface (first surface) side. Subsequently, on the other surface (second surface) side of the SOI substrate 100, a third resist patterned so as to expose portions of the second silicon layer 100b other than those corresponding to the outer frame portion 10 and the support 29. Layer 132 is formed. Thereafter, by using the third resist layer 132 as a mask, the second silicon layer 100b is patterned by etching the second silicon layer 100b to a depth (second predetermined depth) reaching the insulating layer 100c. By performing the silicon layer patterning step, the structure shown in FIG. 5E is obtained. Etching of the second silicon layer 100b in the second silicon layer patterning step may be performed by a dry etching apparatus having high anisotropy and capable of vertical deepening, such as an inductively coupled plasma etching apparatus. In the second silicon layer patterning step, the insulating layer 100c is used as an etching stopper layer.

After the second silicon layer patterning step, a mirror forming substrate is formed by performing an insulating layer patterning step of etching unnecessary portions of the insulating layer 100c of the SOI substrate 100 from the other surface (second surface) side of the SOI substrate 100. 1 is formed. Subsequently, the second resist layer 131 and the third resist layer 132 are removed. The silicon oxide film 111b is also removed. Thereafter, by performing a joining step of joining the mirror forming substrate 1 to the first cover substrate 2 and the second cover substrate 3 by anodic bonding or the like, the MEMS mirror 403 having the structure shown in FIG. 5F is obtained.

In the above-described bonding process, from the viewpoint of protecting the mirror surface 21 of the mirror forming substrate 1, after performing the first bonding process of bonding the first cover substrate 2 and the mirror forming substrate 1, It is preferable to perform a second joining process for joining the second cover substrate 3. Here, in the first bonding process, first, a laminated body in which the first cover substrate 2 in which the first concave portion 201 and each through hole 202 are formed on the first glass substrate 200 and the mirror forming substrate 1 are overlapped. Is heated to a predetermined bonding temperature (for example, about 300 ° C. to 400 ° C.) in a vacuum with a predetermined degree of vacuum (for example, 10 Pa or less), between the first silicon layer 100a and the first cover substrate 2. A predetermined voltage (for example, about 400 V to 800 V) is applied between the first cover substrate 2 side and the low potential side, and this state is maintained for a predetermined bonding time (for example, about 20 minutes to 60 minutes). . In the second bonding process, anodic bonding between the second silicon layer 100b and the second cover substrate 3 is performed in accordance with the first bonding process described above. Note that the bonding method for bonding the mirror forming substrate 1 and the

cover substrates

2 and 3 is not limited to anodic bonding, and may be, for example, a room temperature bonding method. In addition, after the first silicon layer patterning step, the SOI substrate 100 and the first cover substrate 2 are bonded together, and then the second silicon layer patterning step and the insulating layer patterning step are performed, so that the mirror forming substrate 1 is formed. Then, the mirror forming substrate 1 and the second cover substrate 3 may be bonded.

Next, the operation of the MEMS mirror 403 will be described.

In the MEMS mirror 403, a pulse voltage for driving the movable portion 20 is applied between the first movable electrode 22 and the first fixed electrode 12 facing each other via the pair of

pads

13 and 13. Electrostatic force is generated between the first movable electrode 22 and the first fixed electrode 12, and the movable part 20 rotates about the axis in the y-axis direction. Thus, in the MEMS mirror 403, an electrostatic force can be periodically generated by applying a pulse voltage having a predetermined drive frequency between the first movable electrode 22 and the first fixed electrode 12. The movable part 20 can be swung.

Here, the above-described movable portion 20 is not in a horizontal posture (a posture parallel to the xy plane) and is tilted slightly though it is stationary due to internal stress. For example, the first movable electrode When a pulse voltage is applied between the first fixed electrode 12 and the first fixed electrode 12, a driving force in a direction substantially perpendicular to the movable portion 20 (z-axis direction) is applied to the movable portion 20 even from a stationary state. Rotates while twisting the pair of first torsion springs 30, 30 about the pair of first torsion springs 30, 30. Then, when the driving force between the first movable electrode 22 and the first fixed electrode 12 is released when the movable comb tooth piece 22b and the fixed comb tooth piece 12b are in a posture that completely overlaps, The movable portion 20 continues to rotate while twisting the pair of first

torsion spring portions

30 and 30 by inertial force. Then, when the inertial force in the rotation direction of the movable portion 20 and the restoring force of the pair of first

torsion spring portions

30 and 30 become equal, the rotation of the movable portion 20 in the rotation direction stops. To do. At this time, when a pulse voltage is applied again between the first movable electrode 22 and the first fixed electrode 12 to generate an electrostatic force, the movable portion 20 is moved between the pair of first

torsion spring portions

30 and 30. By the restoring force and the driving force of the first driving means, rotation in the opposite direction is started. The movable part 20 repeats the rotation by the driving force of the first driving means and the restoring force of the pair of first

torsion spring parts

30, 30 to rotate the pair of first

torsion spring parts

30, 30. Swings as a shaft.

In addition, the application form and frequency of the drive voltage between the 1st movable electrode 22 and the 1st fixed electrode 12 are not specifically limited, For example, the 1st movable electrode 22 and the 1st fixed electrode 12 are used. The voltage applied between the two may be a sine wave voltage.

By the way, the MEMS mirror 403 includes, for example, the first fixed electrode 12 and the second movable electrode using the potential of the pad 13a to which the first movable electrode 22 and the second fixed electrode 26 are electrically connected as a reference potential. 27. By periodically changing the respective potentials, the movable portion 20 can be rotated about the axis of the pair of first

torsion spring portions

30, 30, and the mirror portion 24 can be turned to the pair of second torsion springs. The

spring portions

25 and 25 can be rotated around the axis. In short, in the MEMS mirror 403 in the present embodiment, a pulse voltage for driving the movable portion 20 is interposed between the opposed first fixed electrode 12 and first movable electrode 22 via the pair of

pads

13b and 13a. As a result, an electrostatic force is generated between the first fixed electrode 12 and the first movable electrode 22, and the movable part 20 rotates about the axis in the y-axis direction. In the MEMS mirror 403, a pulse voltage for driving the mirror portion 24 is applied between the opposed second fixed electrode 26 and the second movable electrode 27 via the pair of

pads

13a and 13c. As a result, an electrostatic force is generated between the second fixed electrode 26 and the second movable electrode 27, and the mirror portion 24 rotates about the axis in the x-axis direction. Therefore, in the MEMS mirror 403 in this embodiment, an electrostatic force is periodically generated by applying a pulse voltage having a predetermined first driving frequency between the first fixed electrode 12 and the first movable electrode 22. Can be generated, the entire movable part 20 can be swung, and a pulse voltage of a predetermined second driving frequency is applied between the second fixed electrode 26 and the second movable electrode 27. By doing so, an electrostatic force can be periodically generated and the mirror part 24 of the movable part 20 can be swung. The mirror forming substrate 1 is formed on the surface of the portion of the first silicon layer 100a where the reflective film 21a is not formed on the space surrounded by the outer frame portion 10 and the first cover substrate 2. A film 111a (see FIG. 5F) is formed.

In the MEMS mirror 403 according to the present embodiment, the vibration system configured by the movable portion 20 and the pair of first

torsion spring portions

30 and 30 between the first fixed electrode 12 and the first movable electrode 22 is used. By applying a pulse voltage having a frequency approximately twice the resonance frequency, the movable part 20 is driven with a resonance phenomenon, and the mechanical deflection angle (inclination with respect to a horizontal plane parallel to the xy plane) is increased. . Further, in the MEMS mirror 403 in the present embodiment, the vibration constituted by the mirror portion 24 and the pair of second

torsion spring portions

25 and 25 between the second fixed electrode 26 and the second movable electrode 27. By applying a pulse voltage having a frequency approximately twice the resonance frequency of the system, the mirror unit 24 is driven with a resonance phenomenon, and a mechanical deflection angle (on the surface of the movable frame unit 23 on the first cover substrate 2 side) is driven. (Tilt with respect to parallel plane as reference) increases.

By the way, the determination unit controls the first laser driving device that drives the detection laser 401, the second laser driving device that drives the display laser 411, and the mirror driving device that drives the MEMS mirror 403. And the like (not shown). Here, the mirror driving device is constituted by a first driving means constituted by the first movable electrode 22 and the first fixed electrode 12, a second movable electrode 27 and a second fixed electrode 26. Second driving means, and a power source for applying the first driving voltage to the first driving means and applying the second driving voltage to the second driving means.

In the mirror driving device, the control device detects a mechanical deflection angle of the movable portion 20 relative to the fixed frame portion 10 with a first driving voltage applied from the power source to the first driving means of the MEMS mirror 403. And a second driving voltage applied from the power source to the second driving unit of the MEMS mirror 403 to detect the mechanical deflection angle of the mirror unit 24 with respect to the movable frame unit 23. The second DC bias voltage is superimposed and applied.

Here, since a minute voltage change occurs in the first DC bias voltage in accordance with a change in the relative position (mechanical deflection angle) of the movable part 20 with respect to the fixed frame part 10, the movable part 20 is By monitoring the first DC bias voltage between the pair of

pads

13b, 13a for driving, the inclination of the movable portion 20 relative to the fixed frame portion 10 can be detected. Further, since a minute voltage change occurs in the second DC bias voltage in accordance with a change in the relative position (mechanical deflection angle) of the mirror unit 24 with respect to the movable frame unit 23, the mirror unit 24 is driven in the control device. By monitoring the second DC bias voltage between the pair of

pads

13a and 13c for the purpose, the inclination of the mirror part 24 relative to the movable frame part 23 can be detected. The control device can determine the normal direction of the center of the mirror surface 21 based on these inclinations, and the reflection directions (displays) of the detection laser beam LB and the display laser beam LB2 reflected by the mirror surface 21. The scanning position on the portion 410 can be obtained. Note that the control device includes a memory that stores data in which the reflection direction of the MEMS mirror 403 and the drive condition of the display laser 411 are associated with each other in accordance with a predetermined image displayed on the display unit 410. The drive condition of the display laser 411 is changed based on the data stored in the memory.

Therefore, for example, as shown in FIG. 9, the sensor device installs the display unit 410 near the door 470 on the indoor wall surface 460, and the display unit 410 has an external device (for example, a lighting device, an air conditioner, or a television). It is possible to display an image of a virtual switch (hereinafter referred to as a virtual switch) 440 for ON / OFF control of the image and to detect the presence or absence of the object 406 at an arbitrary position in the detection target space 405. Become. In the example of FIG. 9, in the image of the virtual switch 440, there is a case where the object 406 is at the position of the virtual first switch element 441 composed of a square image on the left side of the character “ON”, and the character “OFF”. The determination unit can determine when the object 406 is present at the position of the virtual second switch element 442 formed of the left square image. Therefore, in accordance with the determination result of the determination unit, a transmission unit that transmits to the external device a remote control signal for on / off control of a switch inserted between the external device and a power source that supplies power to the external device If an antenna (such as an antenna) is provided, an embedding hole for embedding an embedding type switch, which is a kind of embedding type wiring apparatus, can be formed in a construction material such as an indoor wall, The virtual switch 440 can be provided by installing the display unit 410 on the wall surface 460 formed of the surface of the construction material without providing the preceding wiring for constructing the wiring device on the back of the wall or the like. In installing the display unit 410 on the construction material, for example, the display unit 410 may be attached to the construction material with a pressure-sensitive adhesive or the like previously provided on the back surface side.

As shown in FIG. 7, the sensor device described above includes a housing 420 that houses a detection laser 401, a half mirror 402, a MEMS mirror 403, a light detection unit 404, a display laser 411, a dichroic mirror 412, a lens 407, and the like. I have. In the housing 420, the detection laser beam LB1 (see FIG. 1B) and the display laser beam LB2 (see FIG. 1D) reflected by the MEMS mirror 403 toward the detection target space 405 side, and the detection target space 405 A passage portion (not shown) is formed that allows the detection laser light LB1 (see FIG. 1C) reflected by the display portion 410 and the object 406 to travel toward the MEMS mirror 403. This passing portion may be a through hole or may be formed of a material that transmits the detection laser beam LB1 and the display laser beam LB2. In the housing 420, a holding member (not shown) that positions and holds the detection laser 401, the half mirror 402, the MEMS mirror 403, the light detection unit 404, the display laser 411, the dichroic mirror 412, the lens 407, and the like. ) Is arranged.

By the way, in the sensor device described above, a part of the detection laser beam LB1 is scattered by the half mirror 402, the MEMS mirror 403, or the like, or reflected by the inner surface of the housing 420, so that the light receiving surface of the light detection unit 404 is received. There is a concern that stray light that reaches 404a may be generated, and the S / N ratio of the output of the light detection unit 404 may decrease.

Therefore, it is preferable that the sensor device includes a light shielding member 430 disposed around the optical path of the detection laser beam LB1 and the display laser beam LB2 to block stray light. In the sensor device, by providing the light blocking member 430, stray light reaching the light detection unit 404 can be reduced, and the S / N ratio of the output of the light detection unit 404 can be improved. Although the light shielding member 430 is formed of a black resin molded product, it is sufficient that the light shielding member 430 can block stray light, and the material and forming method of the light shielding member 430 are not particularly limited. In the illustrated example, six light shielding members 430 are provided, but the number of light shielding members 430 is not particularly limited, and may be one.

In the sensor device, the inner surface of the housing 420 is preferably a rough surface that scatters stray light. Accordingly, the sensor device can reduce stray light that reaches the light receiving surface 404a of the light detection unit 404. As a processing method for making the inner surface of the housing 420 rough, for example, there is blast processing. The means for reducing the stray light that enters the inner surface of the housing 420 and reaches the light receiving surface 404a of the light detection unit 404 is not limited to the example in which the inner surface of the housing 420 is a rough surface. For example, when the material of the housing 420 is metal, the inner surface side of the housing 420 may be painted with a black coating material, or black alumite may be formed.

In assembling the sensor device described above, first, a body 420a (see FIG. 8A) that constitutes a part of the housing 420 is prepared. After the holding member is attached to the body 420a, as shown in FIG. In 420a, a detection laser 401, a half mirror 402, a MEMS mirror 403, a light detection unit 404, a display laser 411, a dichroic mirror 412, a lens 407, and the like are arranged, and the detection laser 401 is driven to detect the light detection unit 404. The optical axis is adjusted so that the output of is maximized (passive alignment is performed). Subsequently, as shown in FIG. 8C, a light shielding member 430 is disposed. Thereafter, a cover (not shown) that forms the housing 420 together with the body 420a may be coupled to the body 420a.

In the sensor device of the present embodiment described above, the detection laser 401, the half mirror 402 that reflects and transmits the detection laser light LB1 emitted from the detection laser 401, and the detection laser reflected by the half mirror 402 The MEMS mirror 403 that reflects the light LB1 to the detection target space 405 side, and is reflected by the MEMS mirror 403 after being reflected by the object 406 in the detection target space 405 that is located on the opposite side of the MEMS mirror 403 across the half mirror 402. The detection laser beam LB1 and the determination unit that determines the presence or absence of the object 406 in the detection target space 405 based on the output of the light detection unit 404. The detection laser 401 and the MEMS Optical axis OA1 between the mirror 403 and optical axis OA between the MEMS mirror 403 and the light detection unit 404 Preparative, so are matched between the MEMS mirror 403 and the half mirror 402, less affected by ambient light, and makes it possible to downsize.

In the sensor device of this embodiment, the display unit 410 disposed in the detection target space 405, the display laser 411, the detection laser 401, and the half mirror 402 are positioned and emitted from the display laser 411. A dichroic mirror 412 that reflects the display laser beam LB 2 that has been transmitted to the half mirror 402 side and transmits the detection laser beam LB 1 from the detection laser 401. The half mirror 402 is for display from the display laser 401. Since the laser beam LB2 is reflected toward the MEMS mirror 403, the half mirror 402 and the MEMS mirror 403 are shared by the optical system for displaying an image on the display unit 410 and the optical system for detecting the object 406. The majority of the optical axes of both optical systems can be aligned on the same axis, and these optical systems have separate optical paths. Compared to the case of the determination, the size and weight can be reduced, and the optical paths of the detection laser beam LB1 and the display laser beam LB2 in the detection target space 405 can be matched with high accuracy. .

By the way, the sensor device is not limited to the arrangement shown in FIG. 1A, and may be arranged as shown in FIG. Here, the light detection unit 404 detects the detection laser light LB <b> 1 reflected by the half mirror 402. 10, the optical axis OA1 between the detection laser 401 and the MEMS mirror 403 and the optical axis OA2 between the MEMS mirror 403 and the light detection unit 404 are also expressed in the same manner as in the configuration of FIG. 1A. The mirror 403 and the half mirror 402 are matched. In the example of FIG. 10, in the half mirror 402, a part of the detection laser light emitted from the detection laser 401 passes through the half mirror 402 and enters the optical mirror 403, and is reflected on the detection target space 405 side. A part of the detected laser light is arranged to be reflected by the half mirror 402 toward the light detection unit 404. The MEMS mirror 403 reflects the detection laser beam LB1 transmitted through the half mirror 402 to the detection target space 405 side by the mirror surface 21, and also detects the detection laser reflected by the object 406 or the display unit 410 in the detection target space 405. It arrange | positions so that light may be reflected in the optical detection part 404 side with the mirror surface 21 and the half mirror 402 of its own.

In addition, each of the sensor devices described above includes a display laser 412, a dichroic mirror 412, a display unit 410, and the like, which may be provided as appropriate according to the application of the sensor device. Further, the MEMS mirror 403 constituting the optical mirror does not necessarily need to scan the detection laser beam LB1 two-dimensionally, and the reflection direction may be fixed in a specific direction according to the application of the sensor device. . The object 406 is not limited to the finger of a human hand.

While the invention has been described in terms of several preferred embodiments, various modifications and variations can be made by those skilled in the art without departing from the true spirit and scope of the invention, ie, the claims.

Claims

A detection laser configured to emit detection laser light;
An optical mirror configured to reflect the detection laser beam toward the detection target space; and
A sensor device comprising: a light detection unit configured to detect the detection laser light reflected on the detection target space side,
The sensor device further includes a half mirror, which is arranged to reflect and transmit a part and the remaining part of the detection laser light incident on the half mirror, respectively.
The optical mirror is composed of a MEMS device including a movable part and a mirror surface provided on the movable part, and reflects the detection laser light from the half mirror to the detection target space side on the mirror surface, Further, the detection laser beam reflected on the detection target space side is arranged so as to be reflected on the mirror surface to the light detection unit side,
The optical axis between the detection laser and the optical mirror and the optical axis between the optical mirror and the light detection unit are matched between the optical mirror and the half mirror. Sensor device.
The sensor device according to claim 1, further comprising a determination unit configured to determine the presence or absence of an object in the detection target space based on an output of the light detection unit.
The half mirror is a part of the detection laser light reflected from the detection target space side by reflecting a part of the detection laser light emitted from the detection laser to the optical mirror by the half mirror. The sensor device according to claim 1, wherein a part is disposed so as to pass through the half mirror and enter the light detection part.
A display unit disposed in the detection target space;
A display laser configured to emit display laser light for performing predetermined display on the display unit;
A dichroic mirror positioned between the detection laser and the half mirror;
The dichroic mirror is configured such that the display laser light emitted from the display laser is reflected by the dichroic mirror toward the half mirror, and the detection laser light from the detection laser passes through the dichroic mirror. The sensor device according to claim 1, wherein the sensor device is configured as follows.
A lens for condensing the laser beam for detection on the light receiving surface of the light detection unit located between the half mirror and the light detection unit;
The sensor device according to claim 4, wherein the lens is disposed at a position that is in an imaging relationship with the display unit.
5. The sensor device according to claim 4, wherein the display unit includes a screen that retroreflects both the detection laser beam and the display laser beam.
6. The sensor device according to claim 5, wherein the display unit includes a screen that retroreflects both the detection laser beam and the display laser beam.
The sensor according to any one of claims 4 to 7, further comprising a light blocking member disposed around an optical path of the detection laser beam and the display laser beam to block stray light. apparatus.
A housing housing the detection laser, the half mirror, the optical mirror, the light detection unit, the display laser, the dichroic mirror, the lens, and the light shielding member;
The sensor device according to claim 8, wherein an inner surface of the housing is a rough surface that scatters the stray light.