JP5447411B2 - Two-dimensional optical scanning device and image projection device - Google Patents

Description

  The present invention relates to a two-dimensional optical scanning apparatus that two-dimensionally scans light such as a laser and an image projection apparatus using the two-dimensional optical scanning apparatus.

  Currently, an optical scanning device that scans light such as laser light with a vibrating mirror is known (Patent Document 1). In such an optical scanning device, a mirror supported so as to be able to oscillate by a beam portion oscillates in a resonance state by a driving unit such as a piezoelectric element, thereby scanning light incident on the mirror. In recent years, an optical scanning device having a metal structure is also known for the purpose of improving durability (Patent Document 2).

JP 2007-271788 A JP 2006-293116 A

  An optical scanning device as disclosed in Patent Document 1 can scan light only in a one-dimensional direction. In order to generate an image by scanning light two-dimensionally, it is necessary to arrange two optical scanning devices so that their scanning directions are orthogonal to each other. Therefore, for the purpose of extending the lifetime of the optical scanning device, a method of integrating the optical scanning device described in Patent Document 2 with another scanning device that swings in a direction orthogonal to the scanning direction is conceivable. . In the following, this possibility will be examined.

  In general, when generating an image by scanning light two-dimensionally, scanning in one direction (for example, horizontal direction) scanned at high speed and other direction (for example, vertical direction) scanned at low speed Scanning is required. Further, the optical scanning device described in Patent Document 2 can scan at a relatively high speed by driving in a resonance state. Therefore, it is desirable that the optical scanning device described in Patent Document 2 is used for high-speed horizontal scanning, and that another scanning device that scans the optical scanning device in the low-speed vertical direction is combined. In this case, since the entire optical scanning device described in Patent Document 2 needs to be swung, an optical scanning device with a large driving force is required for vertical scanning. For example, an electromagnetically driven optical scanning device combining a permanent magnet and a coil can obtain a large driving force and is suitable for this type of purpose.

  However, according to knowledge newly discovered by the present inventor, there is a possibility that an increase in power consumption may be caused by combining an electromagnetic scanning optical scanning device with the optical scanning device described in Patent Document 2. . Specifically, a magnetic field generated from an electromagnetically driven optical scanning device interferes with a metal structure. That is, when a magnetic field passes through the metal structure, the driving force obtained when a current is passed through the coil is reduced. Further, when the metal structure is displaced in a magnetic field, Lorentz force is applied to the metal structure by electromagnetic induction in a direction that prevents the displacement. Therefore, simply combining the optical scanning device described in Patent Document 2 with an electromagnetically driven optical scanning device may increase power consumption.

  The present invention provides a two-dimensional optical scanning device capable of further scanning a metal structure that scans in one direction in another direction while preventing an increase in power consumption in the other direction by an electromagnetic drive method. An object is to provide an image projection apparatus using a two-dimensional optical scanning device.

In order to solve the above-described problem, one aspect of the present invention includes a mirror portion that includes a reflecting surface that reflects light and is configured to be swingable about a first axis, and one end of the mirror portion on both sides of the mirror portion. A pair of torsion beam portions extending from the mirror portion in parallel to the first axis, and connected to the other ends of the pair of torsion beam portions, spaced apart from the mirror portion and intersecting the first axis And a pair of torsion beam portions provided on the metal structure and exciting a plate wave in the main body portion. A first drive unit capable of swinging the mirror unit around the first axis via a first axis, and extending along a direction of a second axis perpendicular to the first axis, and the metal structure is attached And the shaft portion swings around the second axis. A pedestal for supporting the ability, a magnetic field generating portion, wherein at a distance from the second axis in a first direction perpendicular to the first axis and the second axis is provided in the base portion, the magnetic field generator emits A planar coil provided on the shaft portion in the first direction and spaced apart from the metal structure , the wiring pattern intersecting with the direction of the magnetic field, and an interaction between the current flowing through the planar coil and the magnetic field The second drive unit capable of swinging the shaft portion around the second axis, and allowing the magnetic field to reach the planar coil and allowing the magnetic field to reach the metal structure. A closed magnetic part, and the closed magnetic part has a first closed magnetic member provided between the planar coil and the magnetic field generator and the metal structure in the first direction. With a two-dimensional optical scanning device That. The shaft portion may have an attachment portion extending in the first direction, and the planar coil may be provided on the shaft portion via the attachment portion.

The closed magnetic part has a first closed magnetic member provided between the planar coil and the magnetic field generating part and the metal structure in a first direction orthogonal to the first axis and the second axis . That is, in the first direction, the planar coil and the magnetic field generator are located on one side with the first closed magnetic member interposed therebetween, and the metal structure exists on the other side. Therefore, the magnetic field generated from the magnetic field generation unit reaches the planar coil without being obstructed by the closed magnetic unit. On the other hand, since the first closed magnetic member exists between them, the magnetic field generated from the magnetic field generation unit is prevented from reaching the metal structure. Therefore, when the shaft portion is swung by the second drive portion, the Lorentz force does not act in a direction that prevents the displacement of the metal structure that swings as the shaft portion swings. Further, since the magnetic field is prevented from reaching the metal structure, the decrease in the magnetic field strength at the place where the planar coil is placed is alleviated, and the decrease in the driving force obtained when a current is passed through the planar coil is also alleviated. The Therefore, it is possible to prevent an increase in power consumption when driving the two-dimensional optical scanning device, specifically, swinging the shaft portion.

  The magnetic field generation unit includes a first magnet and a second magnet, and the first magnet and the second magnet each include a first magnetic pole and a second magnetic pole having a polarity different from the first magnetic pole. And the normal vector of the surface to be the first magnetic pole and the normal vector of the surface to be the second magnetic pole are directed in different directions, and the first magnetic pole of the first magnet and the second magnetic pole The second magnetic pole of the magnet is provided on the pedestal portion so as to face each other so as to face each other in a direction along a plane parallel to the first axis and the second axis, and the planar coil includes the first coil It may be provided between the magnet and the second magnet.

  According to this, since the first magnetic pole of the first magnet and the second magnetic pole of the second magnet are opposed to each other, the lines of magnetic force are substantially straight between the first magnet and the second magnet, that is, the magnetic field strength is substantially constant. It becomes. Therefore, the planar coil is always placed in a constant magnetic field strength regardless of the displacement state of the shaft portion. Therefore, when a current is passed through the planar coil, the shaft portion can be oscillated with better response. Further, a magnetic circuit is formed between the first magnet and the second magnet so that the magnetic lines of force pass through the first closed magnetic member. Therefore, it is possible to suppress leakage of the magnetic field from the magnetic field generation unit to the outside. Therefore, the swinging of the metal structure is not hindered, and it is possible to prevent a reduction in power consumption when the shaft portion is swung.

  Furthermore, the closed magnetic part may further include a second closed magnetic member provided on the second magnetic pole of the first magnet and the first magnetic pole of the second magnet.

  According to this, the 2nd closed magnetic member is provided in the outside magnetic pole (namely, the 2nd magnetic pole of the 1st magnet, and the 1st magnetic pole of the 2nd magnet) which the 1st magnet and the 2nd magnet do not counter. Thereby, the magnetic field generated from the second magnetic pole of the first magnet and the first magnetic pole of the second magnet can be prevented from reaching the metal structure. On the other hand, since the planar coil is provided between the first magnet and the second magnet, the magnetic field strength at the position of the planar coil is not changed by the second closed magnetic member. Accordingly, it is possible to further prevent an increase in power consumption when the shaft portion is swung.

  Furthermore, the closed magnetic part may further include a third closed magnetic member provided in the magnetic field generation part so as to face the first closed magnetic member across the magnetic field generation part.

  According to this, the magnetic field generated from the magnetic field generation unit can be further prevented from reaching the metal structure by the third closed magnetic member. On the other hand, since the planar coil is provided between the first magnet and the second magnet, the magnetic field strength at the position of the planar coil is not changed by the third closed magnetic member. Accordingly, it is possible to further prevent a reduction in power consumption when the shaft portion is swung.

  Furthermore, the pedestal portion may further include a shaft support member that rotatably supports the shaft portion.

  Thereby, the resistance when the shaft portion swings is reduced. For this reason, it becomes possible to improve the response of the oscillation of the shaft portion around the second axis.

  Furthermore, the mirror portion may be configured such that the second axis is located on the reflecting surface.

  As a result, even if the shaft is rotated, the reflecting surface is always on the second axis, so that the light is prevented from coming off the mirror, the light is always incident on the mirror, and the light is scanned two-dimensionally without interruption. The

  In order to solve the above-mentioned problems, another aspect of the present invention provides a two-dimensional optical scanning device for scanning light to form an image, and for supplying light to the two-dimensional optical scanning device. An image projection apparatus comprising: a light source; and a light guide for guiding light scanned by the two-dimensional light scanning apparatus to a projection surface.

  According to this, it is possible to obtain an image projection apparatus that prevents an increase in power consumption.

  According to the present invention, a two-dimensional optical scanning device capable of vertically scanning a metal structure to be horizontally scanned by an electromagnetic driving method while preventing an increase in power consumption, and the two-dimensional optical scanning device are provided. It is possible to provide the used image projection apparatus.

2 is a perspective view of a two-dimensional optical scanning device 50. FIG. 3 is a top view of the two-dimensional optical scanning device 50. FIG. 2 is a cross-sectional view of the two-dimensional optical scanning device 50 taken along the line AA. FIG. It is explanatory drawing which showed the effect by the closing magnetic part. 5 is a graph showing the magnetic flux density at a position crossing the magnetic field generator 24. 1 is a diagram showing an image projection device 100 using a two-dimensional optical scanning device 50. FIG.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. As shown in FIGS. 1 to 3, the two-dimensional optical scanning device 50 includes a horizontal scanning unit 10 and a vertical scanning unit 20. The horizontal scanning unit 10 swings the mirror portion 11a of the metal structure 11 around the first axis a. The vertical scanning unit 20 swings the horizontal scanning unit 10 attached to the shaft unit 22 around a second axis b that is orthogonal to the first axis a. The light incident on the mirror portion 11a is two-dimensionally scanned by the swinging perpendicular to the two axes.
[Configuration of Horizontal Scanning Unit 10]
As shown in FIGS. 1 to 3, the horizontal scanning unit 10 includes a metal structure 11 and a piezoelectric element 12 attached on a main body portion 11 c of the metal structure 11. The metal structure 11 includes a mirror portion 11a, a pair of torsion beam portions 11b, a main body portion 11c, and a mounted portion 11d. Hereinafter, the metal structure 11 will be described.

  The mirror portion 11a has a reflecting surface 11a1 that reflects light such as a laser. In the present embodiment, the mirror portion 11a has a circular shape in plan view. However, the shape of the mirror portion 11a is not limited to this, and may be a quadrangular shape or the like in plan view. The reflective surface 11a1 is provided by, for example, a method in which the surface of the mirror portion 11a is mirror-polished, or a dielectric such as sapphire or diamond having a metal thin film formed on the surface is attached to the mirror portion 11a.

  One end of the pair of torsion beam portions 11b is connected to both sides of the mirror portion 11a. The pair of torsion beam portions each extend in a direction away from the mirror portion 11a. In the present embodiment, the extending direction of the pair of torsion beam portions 11b is parallel to the first axis a direction. Specifically, the first axis a passes through the centers of the pair of torsion beam portions 11b. By the pair of torsion beam portions 11b, both sides of the mirror portion 11a are elastically supported so as to be swingable around the first axis a. That is, the pair of torsion beam portions 11b has a role as a torsion bar that supports the mirror portion 11a so as to be swingable about the first axis a.

  The main body portion 11c is connected to the other end of the pair of torsion beam portions 11b, is separated from the mirror portion 11a, and extends in a direction intersecting the first axis a. In the present embodiment, the main body portion 11c extends from the connecting portion with the pair of torsion beam portions 11b in the direction of the support portion 21b described later. The shape of the main body portion 11c is a quadrangular shape in plan view, and a pair of protruding portions protrude from one side like a tuning fork. A pair of torsion beam portions 11b exists between the pair of protruding portions.

  The attached portion 11d is provided at one end of the main body portion 11c opposite to the mirror portion 11a. In the present embodiment, the attached portion 11d has a rectangular shape. In the present embodiment, the attached portion 11d is fixed to a shaft portion 22 described later by a method such as adhesion or welding.

  The metal structure 11 is made of, for example, a stainless plate that is a nonmagnetic material. The outer shape of the metal structure 11 is formed by integrally forming the mirror portion 11a, the torsion beam portion 11b, the main body portion 11c, and the attached portion 11d on the same plane by removing processing such as etching or pressing. Is done. As will be described later, in order to resonate the mirror portion 11a, the metal structure 11 preferably has a spring property. Therefore, the metal structure 11 is composed of a stainless plate manufactured by cold rolling. Even if the stainless steel plate is formed of a non-magnetic stainless material, the non-magnetism changes to weak magnetism by cold rolling. For this reason, the metal structure 11 naturally has weak magnetism regardless of the type of stainless steel constituting the stainless steel plate.

  A piezoelectric element 12 serving as a first drive unit is attached on the main body portion 11c. For example, the piezoelectric element 12 is formed by laminating 0.2 μm to 0.6 μm of gold, platinum, or the like as an electrode layer on both surfaces of a piezoelectric material such as lead zirconate titanate formed into a flat plate having a thickness of 30 μm to 100 μm. It is formed by doing. The piezoelectric element 12 and the main body portion 11c are bonded with a conductive adhesive. This conductive adhesive is, for example, one in which a metal filler composed of silver, gold, copper, etc. is dispersed in a base made of a thermosetting epoxy resin, acrylic resin, silicon resin or the like. It is. First, the piezoelectric element 12 is placed on the conductive adhesive applied to the main body portion 11c. In this state, the conductive adhesive is thermally cured to bond the piezoelectric element 12 and the main body portion 11c. A thin metal wire (not shown) such as gold is connected to the surface of the piezoelectric element 12 by wire bonding or the like. Since the metal structure 11 is formed of a stainless steel plate, the piezoelectric element 12 can be deformed by applying a voltage between the metal structure 11 and the thin metal wire. If the voltage applied to the piezoelectric element 12 is an AC voltage corresponding to the resonance frequency of the horizontal scanning unit 10, a plate wave is excited in the main body portion 11 c as the piezoelectric element 12 is deformed. The plate wave is transmitted to the mirror portion 11a through the main body portion 11c and the pair of torsion beam portions 11b, so that the mirror portion 11a swings around the first axis a at a predetermined resonance frequency.

[Configuration of Vertical Scanning Unit 20]
Next, the vertical scanning unit 20 will be described. As shown in FIGS. 1 to 3, the vertical scanning unit 20 mainly includes a pedestal unit 21, a shaft unit 22, a planar coil 23, a magnetic field generation unit 24, and a closed magnetic unit 26. Hereinafter, the configuration of the vertical scanning unit 20 will be described.

  The pedestal 21 is made of a nonmagnetic material such as synthetic resin or stainless steel, for example. The pedestal portion 21 includes a base portion 21a and a support portion 21b. The base 21a is a plate-like or block-like member that extends parallel to a plane including the first axis a and the second axis b. The support portion 21b extends from one end of the base portion 21a in a direction (upward in FIG. 1) perpendicular to a plane including the first axis a and the second axis b.

  The shaft portion 22 is supported by the support portion 21b so that it can swing around the second axis b. The longitudinal direction of the shaft portion 22 extends along the direction of the second axis b. Specifically, the shaft portion 22 includes a second axis b. The shaft portion 22 is made of, for example, a nonmagnetic material such as synthetic resin or stainless steel. One end of the shaft portion 22 is pivotally supported by a bearing 25 attached to the support portion 21b. In the embodiment shown in FIG. 3, the bearing 25 is a ball bearing, but the bearing 25 is not limited to this, and is a rolling bearing such as a roller bearing, a magnetic bearing, a fluid bearing, a hard chromium / chromium molybdenum plating, or fluorine. A radial bearing such as a sliding bearing that contacts the shaft portion 22 with a low friction material such as a resin coating may be used. The bearing 25 is made of a nonmagnetic material such as synthetic resin or stainless steel.

  As shown in FIG. 3, a spacer 27 made of a nonmagnetic material such as synthetic resin is attached to the tip of the shaft portion 22. As shown in FIG. 3, the spacer 27 has a block shape and hangs down from the tip of the shaft portion 22. As shown in FIGS. 1 and 3, the attached portion 11 d of the metal structure 11 is attached in a state of being placed on the upper end of the spacer 27. That is, the attached portion 11 d is attached to the shaft portion 22 via the spacer 27. Accordingly, the terms “attached”, “coupled”, “connected”, etc. include not only the structure in which one member and another member are directly joined, but also one member and the other as described above. It should be understood that a configuration in which a third member is indirectly joined to the other member is also included. A second axis b that is the rotation center of the shaft portion 22 passes through the upper surface of the metal structure 11, in particular, the reflection surface 11 a 1 of the mirror portion 11 a. For this reason, even if the vertical scanning unit 20 rotates, the reflecting surface 11a1 is always located on the second axis b. Therefore, the light is prevented from coming off the mirror portion 11a, the light is always incident on the mirror portion 11a, and the light is two-dimensionally scanned without interruption. As shown in FIG. 2, the horizontal scanning unit 10 including the metal structure 11 is formed symmetrically in the width direction with the second axis b as the axis of symmetry. As shown in FIG. 3, the metal structure 11 is disposed outside a pair of magnetic field generators 24 described later.

  A flat coil support member 28 is attached to the lower end of the spacer 27. The coil support member 28 is made of a nonmagnetic material such as synthetic resin. The coil support member 28 is disposed in parallel with the metal structure 11 so as to be spaced apart. A planar coil 23 is attached to the surface of the coil support member 28 that faces the base 21a. For example, the planar coil 23 may be a flexible printed circuit board (FPC) in which an adhesive layer is formed on a film-like insulator (base film) and a spiral conductive foil is further formed thereon. The thin-film planar coil 23 is bonded to the lower surface of the coil support member 28. With this structure, the planar coil 23 is disposed in parallel with the metal structure 11. In other words, the metal structure 11 is separated from the planar coil 23 in a direction (height direction) orthogonal to the first axis a and the second axis b. The planar coil 23 may be in a form in which a coil pattern is formed directly on the coil support member 28 instead of the FPC. Further, when the planar coil 23 itself is rigid, such as when the planar coil 23 is constituted by windings, the coil support member 28 is not necessary.

  As shown in FIG. 1, a magnetic field generator 24 is provided on the base 21 a of the pedestal 21. The magnetic field generation unit 24 includes a first magnet 24a and a second magnet 24b. The first magnet 24a and the second magnet 24b are different from each other in the normal vector of the surface serving as the first magnetic pole (eg, N pole) and the normal vector of the surface serving as the second magnetic pole (eg, S pole). It is configured to face the direction. In the present embodiment, the first magnet 24a and the second magnet 24b are arranged so that the N pole and the S pole face away from each other, that is, the normal vector of the surface that becomes the N pole and the method of the surface that becomes the S pole. The line vector is configured to face in the opposite direction. However, even if the configuration is such that the N pole and the S pole do not face each other, they are all included if the normal vectors of the surfaces serving as the magnetic poles are in different directions. The first magnet 24a and the second magnet 24b are provided on the base 21a with the planar coil 23 sandwiched therebetween. The north pole of the first magnet 24a and the south pole of the second magnet 24b are opposed in a direction along a plane parallel to the first axis a and the second axis b. In the present embodiment, the N pole of the first magnet 24a and the S pole of the second magnet 24b are opposed to each other in the direction parallel to the first axis a. However, for example, the N pole of the first magnet 24a and the S pole of the second magnet 24b may be opposed to each other in a direction parallel to the second axis b. In short, the first magnet 24a and the second magnet 24b may be arranged so that a magnetic field for generating a Lorentz force having a vertical component is generated for electrons flowing through the planar coil 23. As a result, as shown in FIG. 4B, the planar coil 23 has the wiring pattern intersecting the direction of the magnetic field generated by the magnetic field generator 24 between the first magnet 24a and the second magnet 24b. Is provided. Then, as shown in FIG. 4B, the planar coil 23 has an intermediate position between the first magnet 24a and the second magnet 24b in the vertical direction, that is, between the first magnet 24a and the second magnet 24b. It is provided at a position where the magnetic field strength between them is the strongest. In the present embodiment, the first magnet 24a and the second magnet 24b are permanent magnets, but may be electromagnets. The first magnetic pole may be set to the S pole and the second magnetic pole may be set to the N pole.

  The closed magnetic part 26 is made of a magnetic material such as iron, and includes a first closed magnetic member 26a, a second closed magnetic member 26b, and a third closed magnetic member 26c. The first closed magnetic member 26 a is provided between the planar coil 23 and the magnetic field generator 24 and the metal structure 11. Specifically, the first closed magnetic member 26a contacts the upper surfaces of the first magnet 24a and the second magnet 24b. As a result, the planar coil 23 and the magnetic field generator 24 are located below the first closed magnetic member 26a, and the metal structure 11 is present above the first closed magnetic member 26a. The second closed magnetic member 26b extends downward from both ends of the first closed magnetic member 26a, and the side surfaces of the first magnet 24a and the second magnet 24b, specifically, the second magnetic pole (eg, S pole) of the first magnet 24a. And a first magnetic pole (for example, N pole) of the second magnet 24b. The third closed magnetic member is provided in the magnetic field generation unit 24 so that both ends thereof are connected to the second closed magnetic member 26b and face the first closed magnetic member 26a across the magnetic field generation unit 24. Specifically, it contacts the lower surfaces of the first magnet 24a and the second magnet 24b. That is, the first magnet 24 a and the second magnet 24 b are connected by the closed magnetic part 26.

When a current flows through the planar coil 23, Lorentz force is generated in the electrons flowing through the planar coil 23 due to the interaction between the electrons flowing through the planar coil 23 and the magnetic field generated by the magnetic field generator 24. By this Lorentz force, the shaft portion 22 is rotated around the second axis b. By controlling the direction and current value of the current flowing through the pair of planar coils 23, the shaft portion 22 can be rotated to an arbitrary rotation angle around the second axis b. When the shaft portion 22 is rotated, the mirror portion 11a is also rotated around the second axis b, so that the light incident on the mirror portion 11a is scanned around the second axis b. Thus, the light incident on the mirror portion 11a is scanned around the first axis a by the resonance of the mirror portion 11a, and the light incident on the mirror portion 11a is rotated around the second axis b by the rotation of the shaft portion 22. By scanning, the light incident on the mirror portion 11a is two-dimensionally scanned.
[Effects of the closed magnetic part 26]
By comparing this embodiment in which the two-dimensional optical scanning device 50 is provided with the closed magnetic part 26 with a comparative example in which the two-dimensional optical scanning device 50 is not provided, the effect produced by the closed magnetic part 26 will be described. As shown in FIG. 4A, when the first magnet 24a and the second magnet 24b are not connected by the closed magnetic part 26 (comparative example), a magnetic field (represented by a schematic magnetic field line in FIG. 4). It leaks outside the magnetic field generator 24. On the other hand, as shown in FIG. 4B, in the present embodiment, since the first magnet 24a and the second magnet 24b are connected by the closed magnetic part 26, the first magnet 24a and the second magnet 24b are connected to each other. In the meantime, a magnetic circuit through which a magnetic field passes through the closed magnetic part 26 is formed. As a result, the magnetic field hardly leaks outside the magnetic field generator 24. Note that the magnetic field generating unit 24 and the closed magnetic unit 26 are not necessarily in contact with each other. Even if they are somewhat separated from each other, the magnetic field from the magnetic field generating unit 24 may pass through the closed magnetic unit 26 to substantially form a magnetic circuit. Actually, when the closed magnetic part 26 and the magnetic field generating part 24 are slightly separated and there is a space between them, the magnetic field tends to become stronger.

  FIG. 5A shows a crossing of the magnetic field generator 24 in a state in which the planar coil 23 and the metal structure 11 are disposed at an intermediate position in the vertical direction between the first magnet 24a and the second magnet 24b. FIG. 5 is a graph showing the result of obtaining the magnetic flux density on a plane with a plane coil 23 by simulation. FIG. On the other hand, FIG. 5 (B) is a diagram showing the present embodiment, in which the planar coil 23 is disposed at an intermediate position in the vertical direction between the first magnet 24a and the second magnet 24b, and the metal structure 11 is The magnetic flux density on the plane where the planar coil 23 is located across the pair of magnetic field generating parts 24 in a state where the magnetic field generating part 24 is separated from the planar coil 23 and surrounded by the closed magnetic part 26 is obtained by simulation. It is a graph which shows a result.

  If the metal structure 11 is provided between the first magnet 24a and the second magnet 24b as in the comparative example shown in FIG. 5A, the metal structure 11 is weakly magnetic as described above. The magnetic field emitted from the first magnet 24a is transmitted through the metal structure 11 to the second magnet 24b. As a result, similarly, the magnetic flux density at the position where the planar coil 23 provided between the first magnet 24a and the second magnet 24b is present decreases. Actually, as shown in FIG. 5A, the magnetic flux density at the position where the planar coil 23 is present is significantly smaller than both sides, and is 0.1 T or less. In the structure as shown in FIG. 5A, a magnetic field also passes through the weak magnetic metal structure 11. Therefore, the metal structure 11 is restrained by the magnetic field from the magnetic field generation unit 24, and the swinging of the metal structure 11 is hindered.

On the other hand, in the present embodiment shown in FIG. 5B, the magnetic field generator 24 is surrounded by the closed magnetic part 26. The planar coil 23 is provided between the first magnet 24a and the second magnet 24b, and the metal structure 11 faces the planar coil 23 and the magnetic field generator 24 with the first closed magnetic member 26a interposed therebetween. For this reason, the fall of the magnetic flux density in the position in which the planar coil 23 is provided is suppressed. Actually, as shown in FIG. 5B, the magnetic flux density at the position where the planar coil 23 exists is smaller than both sides, but is significantly larger than that in FIG. is there. As described above, in this embodiment, the magnetic field generation unit 24 is surrounded by the closed magnetic unit 26, thereby suppressing a decrease in magnetic flux density on the planar coil 23 caused by the magnetic field passing through the metal structure 11. The As a result, an increase in power consumption is prevented when a current is passed through the planar coil 23. At the same time, since the restraint of the metal structure 11 due to the magnetic field passing through the metal structure 11 is also suppressed, the horizontal scanning unit 10 is rotated around the second axis b with good response.
[Description of Image Projecting Apparatus 100]
Next, the image projection apparatus 100 will be described with reference to FIG. The two-dimensional optical scanning device 50 can be used in the image projection device 100 as a configuration that scans light to form an image. The image projecting device 100 is a device that causes a viewer to visually recognize a virtual image by projecting an image on the retina 902 using a light beam incident on the pupil 901 of the viewer. This device is also called a retinal scanning display.

  The image projection apparatus 100 includes a light beam generation unit 150, an optical fiber 161, a collimating optical system 162, a vertical driver 181, a horizontal driver 182, a two-dimensional optical scanning device 50, and an imaging optical system 190. The light beam generation means 150 includes a video signal processing circuit 120, a light source unit 130, and an optical multiplexing unit 140. The video signal processing circuit 120 generates a B signal, a G signal, an R signal, a horizontal synchronization signal, and a vertical synchronization signal for forming an image based on a video signal input from the outside.

  The light source unit 130 includes a B laser driver 131, a G laser driver 132, an R laser driver 133, a B laser 134, a G laser 135, and an R laser 136. The B laser driver 131 drives the B laser 134 so as to generate a blue light beam having an intensity corresponding to the B signal from the video signal processing circuit 120. The G laser driver 132 drives the G laser 135 so as to generate a green light beam having an intensity corresponding to the G signal from the video signal processing circuit 120. The R laser driver 133 drives the R laser 136 so as to generate a red light beam having an intensity corresponding to the R signal from the video signal processing circuit 120. The B laser 134, the G laser 135, and the R laser 136 can be configured using, for example, a semiconductor laser or a solid-state laser with a harmonic generation mechanism.

  The optical multiplexing unit 140 includes collimating optical systems 141, 142, and 143, dichroic mirrors 144, 145, and 146 for multiplexing the collimated laser beams, and a concentrator that guides the combined laser beams to the optical fiber 161. And an optical optical system 147. The blue laser light emitted from the B laser 134 is collimated by the collimating optical system 141. The collimated blue laser light is incident on the dichroic mirror 144. Green laser light emitted from the G laser 135 is collimated by the collimating optical system 142. The collimated green laser light is incident on the dichroic mirror 145. The red laser light emitted from the R laser 136 is collimated by the collimating optical system 143. The collimated red laser light is incident on the dichroic mirror 146. The blue, green, and red laser beams respectively incident on the dichroic mirrors 144, 145, and 146 are reflected or transmitted in a wavelength selective manner and are combined as one light beam, and reach the condensing optical system 147. The combined laser light is condensed by the condensing optical system 147 and enters the optical fiber 161.

  The vertical driver 181 generates a drive current to be supplied to the planar coil 23 of the two-dimensional optical scanning device 50 based on the vertical synchronization signal output from the video signal processing circuit 120. The output side of the vertical driver 181 is connected to the planar coil 23. The vertical driver 181 oscillates and drives the shaft portion 22 at a constant speed, for example, at a frequency of 60 Hz. The horizontal driver 182 generates a drive current to be supplied to the piezoelectric element 12 of the two-dimensional optical scanning device 50 based on the horizontal synchronization signal output from the video signal processing circuit 120. The output side of the horizontal driver 182 is connected to the piezoelectric element 12. The horizontal driver 182 swings and drives the mirror portion 11 a at the resonance frequency (for example, 30 kHz) of the metal structure 11.

  Laser light emitted from the optical fiber 161 is collimated by the collimating optical system 162. The collimated laser beam is incident on the mirror portion 11 a of the two-dimensional optical scanning device 50. The piezoelectric element 12 of the two-dimensional optical scanning device 50 vibrates the mirror portion 11 a by the drive current supplied from the horizontal driver 182. Due to this vibration, the laser light incident on the mirror portion 11a is scanned in the horizontal direction. The planar coil 23 of the two-dimensional optical scanning device 50 rotates the horizontal scanning unit 10 by the drive current supplied from the vertical driver 181 to scan the laser light incident on the mirror portion 11a in the vertical direction. The horizontal direction is, for example, the left-right direction with respect to the user. Further, the vertical direction is, for example, a vertical direction with respect to the user. However, the horizontal direction may be defined in the vertical direction with respect to the user, and the vertical direction may be defined in the horizontal direction with respect to the user. The laser light incident on the mirror portion 11a of the two-dimensional light scanning device 50 is converted into two-dimensional scanning light scanned in the horizontal direction and the vertical direction. The imaging optical system 190 is composed of a single lens or a plurality of lenses. The two-dimensional scanning light is imaged by the imaging optical system 190. In other words, the two-dimensional scanning light enters the observer's pupil 901 as parallel rays through the imaging optical system 190. That is, an image is presented to the observer.

  In the above-described embodiment, the light source unit 130 includes the laser drivers 131 to 133 and the lasers 134 to 136. However, the light source unit 130 may be a fluorescent tube such as a light bulb or a cold cathode tube, an LED, or the like. There is no problem. Although the image projection apparatus 100 has been described as an example of a retinal scanning display, it is needless to say that the two-dimensional optical scanning apparatus 50 of the present invention can also be used for the image projection apparatus 100 that projects an image on a wall surface or a screen. In this case, instead of the imaging optical system 190 in the above-described embodiment, an imaging optical system for focusing on a screen located at a predetermined distance is required.

  In the embodiment described above, the magnetic field generator 24 is arranged so that the planar coil 23 is sandwiched between the first magnet 24a and the second magnet 24b. However, there is no problem even if the magnetic field generation unit 24 is configured by a single magnet and the horizontal scanning unit 10 is rotated by applying a magnetic field to the planar coil 23. Even in this embodiment, if the closed magnetic part 26 is provided so as to surround the magnetic field generating part 24, the planar coil 23 is provided inside the closed magnetic part 26, and the metal structure 11 is provided outside, the scope of the present invention. include.

  In the embodiment described above, the shaft portion 22 and the bearing 25 are pivotally supported by the base portion 21 so as to be rotatable. However, instead of the shaft portion 22, there is no problem even in an embodiment in which a swinging portion formed of a torsion beam is swingably attached to the base. In the case of this embodiment, the oscillating part is oscillated around the second axis b by the interaction between the current flowing through the planar coil 23 and the magnetic field generated by the magnetic field generating part 24, and the horizontal scanning part 10 is also It is swung around the biaxial line b. In addition, it is preferable that the shaft part 22 is pivotally supported by the base part 21 by the bearing 25 so that rotation is possible. This is because, when a swinging part composed of a torsion beam is attached to the base so as to be able to swing instead of the shaft part 22, when the swinging part swings, a restoring force is applied to the swinging part that is a torsion beam. This is because the oscillating portion causes a single oscillation, and it is difficult to oscillate the horizontal scanning portion 10 to a target position. In the embodiment in which the shaft portions 22 and 29 are pivotally supported by the pedestal portion 21 by the bearing 25, the sliding resistance when the shaft portions 22 and 29 rotate is small, so the horizontal scanning portion The responsiveness of the rotation around the 10 second axis b is good.

  Although the present invention has been described above in connection with the most practical and preferred embodiments at the present time, the present invention is not limited to the embodiments disclosed herein. The two-dimensional optical scanning apparatus and the image projection apparatus using the two-dimensional optical scanning apparatus can be changed as appropriate without departing from the spirit or concept of the invention that can be read from the claims and the entire specification. It should be understood as encompassed by the scope.

DESCRIPTION OF SYMBOLS 10 Horizontal scanning part 11 Metal structure 11a Mirror part 11b Torsion beam part 11c Main body part 11d Mounted part 12 Piezoelectric element 20 Vertical scanning part 21 Base part 22 Shaft part 23 Planar coil 24 Magnetic field generation part 25 Bearing 26 Closed magnetic part 26a 1st Closed magnetic member 26b Second closed magnetic member 26c Third closed magnetic member 27 Spacer 50 Two-dimensional optical scanning device 100 Image projection device

Claims (8)

A mirror portion including a reflecting surface for reflecting light and configured to be swingable about a first axis;
A pair of torsion beam portions, one end of which is connected to both sides of the mirror portion and extends from the mirror portion parallel to the first axis;
A body portion connected to the other end of the pair of torsion beam portions, extending from the mirror portion and extending in a direction intersecting the first axis;
A flat metal structure having
It is provided in the metal structure, and can excite the mirror portion around the first axis through the main body portion and the pair of torsion beam portions by exciting plate waves in the main body portion. A first drive unit;
A shaft portion extending along a direction of a second axis perpendicular to the first axis, to which the metal structure is attached;
A pedestal that supports the shaft so as to be swingable about the second axis, and is provided on the pedestal so as to be spaced apart from the second axis in a first direction orthogonal to the first and second axes. Including a wiring pattern that intersects the direction of the magnetic field generated by the magnetic field generator, and a planar coil that is provided in the shaft portion and spaced from the metal structure in the first direction, A second drive part capable of swinging the shaft part around the second axis by an interaction between a current flowing through a planar coil and the magnetic field;
A closed magnetic part that allows the magnetic field to reach the planar coil and prevents the magnetic field from reaching the metal structure,
The closed magnetic part has a first closed magnetic member provided between the planar coil and the magnetic field generating part and the metal structure in the first direction .
A two-dimensional optical scanning device. The shaft portion has an attachment portion extending in the first direction,
The planar coil is provided on the shaft portion via the attachment portion.
The two-dimensional optical scanning device according to claim 1. The magnetic field generator has a first magnet and a second magnet,
The first magnet and the second magnet each have a first magnetic pole and a second magnetic pole having a different polarity from the first magnetic pole,
The normal vector of the surface serving as the first magnetic pole and the normal vector of the surface serving as the second magnetic pole are configured to face different directions,
The pedestal portion facing each other such that the first magnetic pole of the first magnet and the second magnetic pole of the second magnet face each other in a direction along a plane parallel to the first axis and the second axis. Provided in
The planar coil is provided between the first magnet and the second magnet.
Two-dimensional optical scanning apparatus according to claim 1 or 2. The closed magnetic part further includes a second closed magnetic member provided on the second magnetic pole of the first magnet and the first magnetic pole of the second magnet.
The two-dimensional optical scanning device according to claim 3 . The closed magnetic part further includes a third closed magnetic member provided in the magnetic field generation part so as to face the first closed magnetic member across the magnetic field generation part.
The two-dimensional optical scanning device according to claim 3 or 4 . The pedestal portion further includes a shaft support member that rotatably supports the shaft portion.
Two-dimensional optical scanning apparatus according to any one of claims 1-5. The mirror portion is configured such that the second axis is located on the reflective surface;
Two-dimensional optical scanning apparatus according to any one of claims 1-6. A two-dimensional optical scanning device according to any one of claims 1 to 7 , for forming an image by scanning light;
A light source for supplying light to the two-dimensional optical scanning device;
An image projection apparatus comprising: a light guide unit configured to guide light scanned by the two-dimensional light scanning apparatus to a projection surface.

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