JP5803586B2 - Mirror device, optical scanner and image forming apparatus - Google Patents

Description

  The present invention relates to a mirror device, an optical scanner, and an image forming apparatus.

For example, Patent Document 1 discloses an optical scanner that scans light two-dimensionally as an optical scanner for performing drawing by optical scanning with a projector, a printer, or the like.
The optical scanner described in Patent Literature 1 is provided at both ends of the frame-shaped member along the first axis so that the frame-shaped member and the frame-shaped member can be rotated around the first axis. A pair of first shaft members, a movable plate provided on the inner side of the frame-like member and provided with a light reflecting portion having light reflectivity, and the movable plate rotated around a second axis orthogonal to the first axis. A pair of second shaft members that are provided at both ends of the movable plate along the second axis so as to be movable, and that support the movable plate on the frame-shaped member; Are provided on the movable plate with the two first permanent magnets arranged with the first axis sandwiched therebetween, the second permanent magnet with the both poles arranged with the first axis sandwiched therebetween, and the frame-like member. A coil that generates a magnetic field acting on the first permanent magnet and the second permanent magnet by applying a voltage, and a voltage application that applies a voltage to the coil And a stage. The first permanent magnet and the second permanent magnet are inclined with respect to the first axis, and are arranged so that the direction of the first permanent magnet and the direction of the magnetic pole of the second permanent magnet are the same. .

However, in the optical scanner described in Patent Document 1, since the axis of the first permanent magnet is inclined with respect to the first axis, the first shaft member is torsionally deformed while being driven. 2 may also be bent or bent in the vertical direction in FIG. 2 of Document 1, thereby causing a composite stress in the first shaft member, which may break the first shaft member.
Therefore, it is preferable to arrange the first permanent magnet so that the axis thereof is orthogonal to the first axis. The second permanent magnet is also preferably arranged so that its axis is perpendicular to the second axis. As an optical scanner in which the first permanent magnet is arranged so that its axis is perpendicular to the first axis, and the second permanent magnet is arranged so that its axis is perpendicular to the second axis, It is disclosed in Patent Document 2.

However, the optical scanner described in Patent Document 1 has a form called a “moving magnet” in which a permanent magnet is provided on each of the rotating frame-shaped member and the movable plate, whereas the optical scanner described in Patent Document 2 is described. The optical scanner is a combination of a “moving coil type” in which a coil is provided on a frame-like member and a permanent magnet is provided on a movable plate, and a “moving magnet type”.
For this reason, in the optical scanner described in Patent Document 2, since the coil is provided in the frame-shaped member, there is a problem in that the coil generates heat during driving and the frame-shaped member is bent by the heat.

  Therefore, as a method of solving the problem that the frame-shaped member is bent due to the heat generation of the coil, the optical scanner described in Patent Document 2 is applied to the “moving magnet”, that is, the first permanent magnet is replaced with the first permanent magnet. Although it is conceivable that the frame-shaped member is provided so as to be orthogonal to the axis and the second permanent magnet is provided on the movable plate so as to be orthogonal to the second axis, in this case, the following problem occurs.

  First, when the hard magnetic material is magnetized to be the first permanent magnet and the second permanent magnet, it is necessary to magnetize the hard magnetic material before it is set on the frame member and the movable plate. . The reason is that if the first permanent magnet and the second permanent magnet already magnetized are installed on the frame-like member and the movable plate, respectively, the first permanent magnet and the second permanent magnet are each frame-like. When arranged on the member and the movable plate, the first permanent magnet and the second permanent magnet are attracted by a magnetic force, and the structure of the frame-shaped member and the movable plate is destroyed by the force, or the first permanent magnet and This is because the second permanent magnet is attracted and the first permanent magnet and the second permanent magnet cannot be installed. In order to be able to install the first permanent magnet and the second permanent magnet on the frame-shaped member and the movable plate, respectively, it is necessary to increase the distance between the first permanent magnet and the second permanent magnet. Increases in size.

  However, even when the hard magnetic body before magnetization is installed on the frame-shaped member and the movable plate, the magnetization of the first permanent magnet and the axis of the second permanent magnet are orthogonal to each other. Magnetization cannot be performed, the first permanent magnet is provided on the frame-like member so as to be orthogonal to the first axis, and the second permanent magnet is provided on the movable plate so as to be orthogonal to the second axis. There is a problem that the provided optical scanner cannot be realized. Further, when magnetizing one of the first permanent magnet and the second permanent magnet and then magnetizing the other, a large force is applied to the magnetized permanent magnet by the magnetic field for magnetization, and the shaft member (beam ) Is destroyed, and there is a problem that magnetization cannot be performed.

JP 2010-79266 A JP 2004-110005 A

  An object of the present invention is to reduce or reduce the cost of the apparatus while preventing or suppressing the occurrence of composite stress in the second shaft member, and the movable plate is made to be the first shaft and the first shaft. It is an object to provide a mirror device, an optical scanner, and an image forming apparatus that can be rotated (swinged) around a second axis orthogonal to the first axis.

Such an object is achieved by the present invention described below.
A mirror device of the present invention includes a light reflecting portion having light reflectivity, and a movable plate that can swing around a first axis;
A first shaft member connected to both ends of the movable plate in the direction along the first axis;
A frame-shaped member surrounding the movable plate, to which the first shaft member is connected, and swingable around a second axis orthogonal to the first axis;
A second shaft member connected to both ends of the frame-shaped member in a direction along the second axis;
A first permanent magnet that is disposed on the movable plate and has a longitudinal shape in which one magnetic pole and the other magnetic pole are disposed across the first axis;
A second permanent magnet arranged in the frame-like member and having a longitudinal shape in which one magnetic pole and the other magnetic pole are arranged across the second axis,
The first permanent magnet is disposed such that an axis of the first permanent magnet is inclined with respect to an axis of the first shaft member and an axis of the second shaft member,
The second permanent magnet is characterized in that an axis of the second permanent magnet is arranged orthogonal to the axis of the second shaft member.

  Thereby, the movable plate can be rotated (swinged) around the first axis and the second axis orthogonal to the first axis while reducing the size and cost of the apparatus. Moreover, since the first permanent magnet and the second permanent magnet are provided in a simple and small configuration, a large driving force can be obtained even if the number of coils is small. As a result, the scanning angle of the vibration system can be increased and high-speed scanning is also possible.

Further, since the second permanent magnet is arranged so that its axis is orthogonal to the axis of the second shaft member, it is possible to prevent or suppress the occurrence of composite stress in the second shaft member. Moreover, the rotation angle around the second axis of the movable plate can be increased.
Further, the first permanent magnet is arranged such that its axis is inclined with respect to the axis of the first shaft member, whereby the axis of the first permanent magnet and the axis of the second permanent magnet are not orthogonal to each other. Magnetization can be reliably performed in a state in which the hard magnetic body for the first permanent magnet and the hard magnetic body for the second permanent magnet are installed on the frame-shaped member and the movable plate, respectively.

In the mirror device of the present invention, it is preferable that an angle θ formed by the axis of the first shaft member and the axis of the first permanent magnet is 30 ° or more and 60 ° or less.
As a result, the movable plate can be smoothly and reliably rotated around the first axis, and the magnetization can be reliably performed.
In the mirror device according to the aspect of the invention, it is preferable that the second permanent magnet is arranged symmetrically with respect to the axis of the second shaft member.
Thereby, the movable plate can be smoothly rotated around the second axis.

In the mirror device of the present invention, the movable plate has a first recess,
It is preferable that the first permanent magnet is disposed in the first recess.
Thereby, it is possible to reduce the moment of inertia of the first vibration system including the first permanent magnet, the movable plate, and the first shaft member and having the first shaft member as the rotation axis. The size of the apparatus can be reduced.

In the mirror device of the present invention, the frame-like member has a second recess or hole,
It is preferable that the second permanent magnet is disposed in the second recess or the hole.
Thereby, it can prevent or suppress more reliably that a composite stress arises in the 2nd shaft member.

The mirror device of the present invention has the two second permanent magnets,
The two second permanent magnets are preferably arranged symmetrically with respect to the axis of the first shaft member.
Thereby, the movable plate can be rotated more smoothly around the second axis, and the rotation angle of the movable plate around the second axis can be further increased.

An optical scanner of the present invention includes a light reflecting portion having light reflectivity, and a movable plate that can swing around a first axis;
A first shaft member connected to both ends of the movable plate in the direction along the first axis;
A frame-shaped member surrounding the movable plate, to which the first shaft member is connected, and swingable around a second axis orthogonal to the first axis;
A second shaft member connected to both ends of the frame-shaped member in a direction along the second axis;
A first permanent magnet that is disposed on the movable plate and has a longitudinal shape in which one magnetic pole and the other magnetic pole are disposed across the first axis;
A second permanent magnet that is disposed on the frame-shaped member and has a longitudinal shape in which one magnetic pole and the other magnetic pole are disposed across the second axis;
A coil that is arranged opposite to the frame-like member and generates a magnetic field that acts on the first permanent magnet and the second permanent magnet by applying a voltage;
Voltage application means for applying a voltage to the coil,
The first permanent magnet is disposed such that an axis of the first permanent magnet is inclined with respect to an axis of the first shaft member and an axis of the second shaft member,
The second permanent magnet is arranged such that the axis of the second permanent magnet is orthogonal to the axis of the second shaft member,
The voltage applying means includes: a first voltage generating unit that generates a first voltage having a first frequency; a second voltage generating unit that generates a second voltage having a second frequency different from the first frequency; A voltage superimposing unit that superimposes the first voltage and the second voltage, and applying the voltage superimposed by the voltage superimposing unit to the coil, thereby moving the movable plate at the first frequency. It is configured to swing around the second axis and swing around the first axis at the second frequency.

  Thereby, the movable plate can be rotated (swinged) around the first axis and the second axis orthogonal to the first axis while reducing the size and cost of the apparatus. Moreover, since the first permanent magnet and the second permanent magnet are provided in a simple and small configuration, a large driving force can be obtained even if the number of coils is small. As a result, the scanning angle of the vibration system can be increased and high-speed scanning is also possible.

Further, since the second permanent magnet is arranged so that its axis is orthogonal to the axis of the second shaft member, it is possible to prevent or suppress the occurrence of composite stress in the second shaft member. Moreover, the rotation angle around the second axis of the movable plate can be increased.
Further, the first permanent magnet is arranged such that its axis is inclined with respect to the axis of the first shaft member, whereby the axis of the first permanent magnet and the axis of the second permanent magnet are not orthogonal to each other. Magnetization can be reliably performed in a state in which the hard magnetic body for the first permanent magnet and the hard magnetic body for the second permanent magnet are installed on the frame-shaped member and the movable plate, respectively.

An image forming apparatus of the present invention includes a light source that emits light,
An optical scanner that scans the light from the light source,
The optical scanner is
A movable plate provided with a light reflecting portion having light reflectivity and swingable about a first axis;
A first shaft member connected to both ends of the movable plate in the direction along the first axis;
A frame-shaped member surrounding the movable plate, to which the first shaft member is connected, and swingable around a second axis orthogonal to the first axis;
A second shaft member connected to both ends of the frame-shaped member in a direction along the second axis;
A first permanent magnet that is disposed on the movable plate and has a longitudinal shape in which one magnetic pole and the other magnetic pole are disposed across the first axis;
A second permanent magnet that is disposed on the frame-shaped member and has a longitudinal shape in which one magnetic pole and the other magnetic pole are disposed across the second axis;
A coil that is arranged opposite to the frame-like member and generates a magnetic field that acts on the first permanent magnet and the second permanent magnet by applying a voltage;
Voltage application means for applying a voltage to the coil,
The first permanent magnet is disposed such that an axis of the first permanent magnet is inclined with respect to an axis of the first shaft member and an axis of the second shaft member,
The second permanent magnet is arranged such that the axis of the second permanent magnet is orthogonal to the axis of the second shaft member,
The voltage applying means includes: a first voltage generating unit that generates a first voltage having a first frequency; a second voltage generating unit that generates a second voltage having a second frequency different from the first frequency; A voltage superimposing unit that superimposes the first voltage and the second voltage, and applying the voltage superimposed by the voltage superimposing unit to the coil, thereby moving the movable plate at the first frequency. It is configured to swing around the second axis and swing around the first axis at the second frequency.

  Thereby, the movable plate can be rotated (swinged) around the first axis and the second axis orthogonal to the first axis while reducing the size and cost of the apparatus. Moreover, since the first permanent magnet and the second permanent magnet are provided in a simple and small configuration, a large driving force can be obtained even if the number of coils is small. As a result, the scanning angle of the vibration system can be increased and high-speed scanning is also possible.

Further, since the second permanent magnet is arranged so that its axis is orthogonal to the axis of the second shaft member, it is possible to prevent or suppress the occurrence of composite stress in the second shaft member. Moreover, the rotation angle around the second axis of the movable plate can be increased.
Further, the first permanent magnet is arranged such that its axis is inclined with respect to the axis of the first shaft member, whereby the axis of the first permanent magnet and the axis of the second permanent magnet are not orthogonal to each other. Magnetization can be reliably performed in a state in which the hard magnetic body for the first permanent magnet and the hard magnetic body for the second permanent magnet are installed on the frame-shaped member and the movable plate, respectively.

It is a top view which shows 1st Embodiment of the optical scanner of this invention. It is the sectional view on the AA line of FIG. It is a block diagram which shows the voltage application means of the drive means with which the optical scanner shown in FIG. 1 is provided. It is a figure which shows an example of the voltage generated in the 1st voltage generation part shown in FIG. 3, and a 2nd voltage generation part. It is a top view which shows 2nd Embodiment of the optical scanner of this invention. FIG. 6 is a sectional view taken along line B-B in FIG. 5. It is sectional drawing which shows 3rd Embodiment of the optical scanner of this invention. It is sectional drawing which shows 4th Embodiment of the optical scanner of this invention. 1 is a diagram schematically showing an embodiment of an image forming apparatus of the present invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a mirror device, an optical scanner, and an image forming apparatus of the invention will be described with reference to the accompanying drawings. In the following embodiment, a case where the mirror device of the present invention is applied to an optical scanner will be described as a representative example.
<First Embodiment>
1 is a plan view showing a first embodiment of the optical scanner of the present invention, FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1, and FIG. 3 is a voltage application of driving means provided in the optical scanner shown in FIG. FIG. 4 is a block diagram showing the means, and FIG. 4 is a diagram showing an example of the voltage generated in the first voltage generator and the second voltage generator shown in FIG. In the following, for convenience of explanation, the front side of the paper in FIG. 1 is called “up”, the back side of the paper is called “down”, the right side is called “right”, the left side is called “left”, and the upper side in FIG. The upper side, the lower side is called “lower”, the right side is called “right”, and the left side is called “left”.

  As shown in FIGS. 1 and 2, the optical scanner 10 includes a mirror device 1, a holder 17, a coil 30, and a voltage applying unit 40 that applies a voltage to the coil 30. The mirror device 1 includes a movable plate 11 including a movable plate main body 110 and a light reflecting portion 12 having light reflectivity, a pair of shaft members (first shaft members) 13a and 13b, a frame-shaped member 14, and 1 A pair of shaft members (second shaft members) 15a and 15b, a support frame 16, a permanent magnet (second permanent magnet) 20a, and a permanent magnet (first permanent magnet) 20c are provided. The light reflecting portion 12 is provided on the upper surface of the movable plate main body 110.

  The shaft members 15a and 15b are rotated by the permanent magnet 20c, the movable plate 11 (light reflecting portion 12), the shaft members 13a and 13b, the permanent magnet 20a, the frame member 14, and the shaft members 15a and 15b. A second vibration system having a shaft is configured, and the permanent magnet 20c, the movable plate 11 (light reflecting portion 12), and the shaft members 13a and 13b are first shafts having the shaft members 13a and 13b as rotation axes. A vibration system is configured.

The frame-like member 14 is supported on the support frame 16 by shaft members 15a and 15b. The movable plate 11 is disposed inside the frame-shaped member 14 and supported by the frame-shaped member 14 by shaft members 13a and 13b. That is, the frame-shaped member 14 surrounds the movable plate 11. The support frame 16 is supported by the holder 17.
The shape of the movable plate 11 is circular in a plan view in the illustrated configuration, but is not limited thereto, and may be, for example, a polygon such as an ellipse or a rectangle in a plan view. The shape of the frame-shaped member 14 is not particularly limited as long as it is a frame shape in the illustrated configuration, but is not particularly limited as long as it is a frame shape. Other polygons, such as an ellipse and a pentagon, may be sufficient.

The shaft members 13a and 13b and the shaft members 15a and 15b can be elastically deformed, respectively. The shaft members 15a and 15b connect the frame-shaped member 14 and the support frame 16 so that the frame-shaped member 14 can rotate (swing) around the X axis (second axis) shown in FIG. . In this case, the shaft members 15 a and 15 b are connected to both ends of the frame-shaped member 14 in the direction along the X axis, and support the frame-shaped member 14 on both sides of the support frame 16. Further, the shaft members 13a and 13b connect the movable plate 11 and the frame-like member 14 so that the movable plate 11 can be rotated (swinged) around the Y axis (first axis) shown in FIG. Yes. In this case, the shaft members 13 a and 13 b are connected to both ends of the movable plate 11 in the direction along the Y axis, and support the movable plate 11 on both sides of the frame-like member 14. Note that the X axis and the Y axis are orthogonal to each other. Further, the center of the frame member 14 and the center of the movable plate 11 are located on the intersection of the X axis and the Y axis in the plan view of FIG. The axis lines of the shaft members 15a and 15b coincide with the X axis, and the axis lines of the shaft members 13a and 13b coincide with the Y axis.
By making the frame-like member 14 rotatable about the X axis and allowing the movable plate 11 to rotate about the Y axis, the movable plate 11 can be rotated about two axes orthogonal to the X axis and the Y axis. Can do.

  The movable plate 11, the shaft members 13a and 13b, the frame member 14, the shaft members 15a and 15b, and the support frame 16 are integrally formed with, for example, silicon as a main material. By using silicon as a main material, it is possible to realize excellent rotation characteristics and to exhibit excellent durability. Further, fine processing (processing) is possible, and the optical scanner 10 can be downsized. These may be formed using a substrate having a laminated structure such as an SOI substrate. In this case, the movable plate 11, the shaft members 13a and 13b, the frame member 14, the shaft members 15a and 15b, and the support frame 16 are used. Are preferably formed of one layer of a laminated substrate.

The holder 17 is made of, for example, glass or silicon as a main material. The shape of the holder 17 is a concave shape in the configuration shown in the figure and is a quadrangle in plan view, but is not particularly limited as long as the support frame 16 can be supported. The joining method of the support frame 16 and the holder 17 is not specifically limited, For example, you may join using an adhesive agent and may join by anodic bonding. Further, for example, a SiO ₂ layer composed of SiO ₂ as a main material may be interposed between the support frame 16 and the holder 17.

  A permanent magnet 20a is provided on the lower surface (the surface facing the holder 17) of the frame member 14, and a permanent magnet 20c is provided on the lower surface (the surface opposite to the light reflecting portion 12) of the movable plate 11. ing. In addition, the joining method of the permanent magnet 20a and the frame-shaped member 14, and the joining method of the permanent magnet 20c and the movable plate 11 are not specifically limited, respectively, For example, it can join using an adhesive agent. A coil 30 that generates a magnetic field that acts on the permanent magnets 20a and 20c is provided on the upper surface of the holder 17. The coil 30 is electrically connected to the voltage applying means 40. The permanent magnets 20a and 20c, the coil 30, and the voltage applying means 40 constitute driving means for rotating the movable plate 11 and the frame-like member 14.

The permanent magnet 20a has a longitudinal shape, in the illustrated configuration, a plate-like and straight rod shape, and is magnetized in the longitudinal direction. In other words, the direction of the line segment connecting the south pole and the north pole of the permanent magnet 20a coincides with the longitudinal direction of the permanent magnet 20a. In other words, the line segment connecting the S pole and the N pole of the permanent magnet 20a coincides with the axis of the permanent magnet 20a.
The permanent magnet 20a is arranged such that both poles sandwich the X axis. That is, the permanent magnet 20a is disposed so that each end (magnetic pole) is located in two regions divided by the X axis. And the permanent magnet 20a is arrange | positioned so that the axis line may orthogonally cross with respect to an X-axis. Thereby, the movable plate 11 can be smoothly and reliably rotated around the X axis, and the rotation angle of the movable plate 11 around the X axis can be increased. Moreover, it can prevent or suppress that composite stress arises in the shaft members 15a and 15b.
The shape of the permanent magnet 20a is not particularly limited as long as it is a longitudinal shape.

Further, the permanent magnet 20c has a longitudinal shape, which is a plate-like and straight bar shape in the illustrated configuration, and is magnetized in the longitudinal direction. That is, the direction of the line segment connecting the south pole and the north pole of the permanent magnet 20c coincides with the longitudinal direction of the permanent magnet 20c. In other words, the line segment connecting the south pole and the north pole of the permanent magnet 20c coincides with the axis of the permanent magnet 20c.
The permanent magnet 20c is arranged such that both poles sandwich the Y axis. And the permanent magnet 20c is arrange | positioned so that the axis line may incline with respect to an X-axis and a Y-axis. Further, the permanent magnet 20c is arranged such that both poles sandwich the X axis. That is, the permanent magnet 20c is arranged so that each end (magnetic pole) is located in two regions divided by the X axis, and is located in two regions divided by the Y axis. Has been placed. Since the axis of the permanent magnet 20c is inclined with respect to the Y axis, the axis of the permanent magnet 20c and the axis of the permanent magnet 20a are not orthogonal to each other. Each hard magnetic body can be reliably magnetized in a state where the hard magnetic bodies before magnetization for 20c are installed on the frame-shaped member 14 and the movable plate 11, respectively.
In addition, the shape of the permanent magnet 20c will not be specifically limited if it is a longitudinal shape.

  Further, the angle θ between the Y axis, that is, the axis of the shaft members 13a and 13b and the axis of the permanent magnet 20c (the inclination angle of the axis of the permanent magnet 20c with respect to the Y axis) θ is not particularly limited, but is 30 ° or more and 60 °. It is preferably below, more preferably 45 ° to 60 °, and even more preferably 45 °. By providing the permanent magnet 20c in this manner, the movable plate 11 can be smoothly and reliably rotated around the Y axis, and the magnetization can be reliably performed. On the other hand, if the inclination angle θ is less than the lower limit value, the movable plate 11 is sufficiently rotated around the Y axis depending on various conditions such as the strength of the voltage applied to the coil 30 by the voltage applying means 40. It may not be possible. On the other hand, when the inclination angle θ exceeds the upper limit, depending on various conditions, the hard magnetic body before magnetization is placed on the frame-like member 14 and the movable plate 11 and magnetized at the same time to make it permanent. When the magnets 20a and 20c are used, the magnets may not be sufficiently magnetized. When magnetizing one of the permanent magnets 20a and 20c and then magnetizing the other, a large force is applied to the magnetized permanent magnet by the magnetic field for magnetization, and the shaft member is destroyed. Magnetism may not be possible.

Further, the permanent magnet 20a is arranged so as to be line-symmetric with respect to the X axis, that is, the axis of the shaft members 15a and 15b in plan view. Thereby, the movable plate 11 can be smoothly rotated around the X axis.
Further, the permanent magnet 20 c is arranged so that the center thereof coincides with the center of the movable plate 11 in plan view. And the permanent magnet 20c is arrange | positioned so that it may become point symmetrical with respect to the center of the movable plate 11 by planar view. Thereby, the movable plate 11 can be smoothly rotated around the X axis and the Y axis.
In the present embodiment, the permanent magnet 20a is provided on the lower surface of the frame-shaped member 14 (the surface facing the holder 17). However, the present invention is not limited to this, and the permanent magnet 20a is formed on the upper surface of the frame-shaped member 14 ( The surface on the side where the light reflecting portion 12 is provided) may be provided, or may be provided on both the lower surface and the upper surface of the frame-shaped member 14.

As the permanent magnets 20a and 20c, for example, magnets magnetized with hard magnetic materials such as neodymium magnets, ferrite magnets, samarium cobalt magnets, alnico magnets, and bond magnets can be suitably used. Further, when magnetizing the hard magnetic material to make the permanent magnets 20 a and 20 c, the magnetism is performed after the hard magnetic material before magnetization is installed on the frame-shaped member 14 and the movable plate 11. If the permanent magnets 20a and 20c that have already been magnetized are to be installed on the frame-shaped member 14 and the movable plate 11, the permanent magnets 20a and 20c are disposed on the frame-shaped member 14 and the movable plate 11. The permanent magnet 20a and the permanent magnet 20c are attracted by a magnetic force, and the structure of the frame-like member 14 and the movable plate 11 is destroyed by the force, or the permanent magnet 20a and the permanent magnet 20c are attracted to each other. This is because 20a and 20c cannot be installed.
In the optical scanner 10, since the axis of the permanent magnet 20a and the axis of the permanent magnet 20c are not orthogonal, the magnetization can be reliably performed.

A coil 30 is provided immediately below the permanent magnets 20a and 20c. That is, the coil 30 is provided so as to face the lower surface of the movable plate 11 and the frame-like member 14. Thereby, the magnetic field which generate | occur | produces from the coil 30 can be made to act on the permanent magnets 20a and 20c efficiently. Thereby, power saving and size reduction of the optical scanner 10 can be achieved.
The coil 30 is electrically connected to the voltage applying means 40. Then, when a voltage is applied to the coil 30 by the voltage applying means 40, a magnetic field having a magnetic flux orthogonal to the X axis and the Y axis is generated from the coil 30. The coil 30 may be wound around a magnetic core.

As shown in FIG. 3, the voltage applying means 40 includes a first voltage generator 41 that generates a first voltage V1 for rotating the movable plate 11 around the X axis, and a movable plate 11 around the Y axis. A second voltage generator 42 for generating a second voltage V2 for rotating the first voltage V2, and a voltage superimposing unit for superimposing the first voltage V1 and the second voltage V2 and applying the voltage to the coil 30. 43.
As shown in FIG. 4A, the first voltage generator 41 generates a first voltage V1 (vertical scanning voltage) that periodically changes at a period T1.

The first voltage V1 has a waveform like a sawtooth wave. Therefore, the optical scanner 10 can effectively perform vertical scanning (sub-scanning) of light. Note that the waveform of the first voltage V1 is not limited to this. Here, the frequency (1 / T1) of the first voltage V1 is not particularly limited as long as it is a frequency suitable for vertical scanning, but is preferably 30 to 80 Hz (about 60 Hz).
In the present embodiment, the frequency of the first voltage V1 is composed of the permanent magnet 20c, the movable plate 11, the shaft members 13a and 13b, the permanent magnet 20a, the frame member 14, and the shaft members 15a and 15b. The frequency is adjusted to be different from the torsional resonance frequency (resonance frequency) of the second vibration system.

On the other hand, as shown in FIG. 4B, the second voltage generator 42 generates a second voltage V2 (horizontal scanning voltage) that periodically changes at a period T2 different from the period T1. .
The second voltage V2 has a waveform like a sine wave. Therefore, the optical scanner 10 can effectively perform main scanning with light. Note that the waveform of the second voltage V2 is not limited to this.
The frequency of the second voltage V2 (second frequency) is preferably larger than the frequency of the first voltage V1 (first frequency). That is, the period T2 is preferably shorter than the period T1. Thereby, it is possible to rotate the movable plate 11 around the Y axis at the second frequency while rotating the movable plate 11 around the X axis at a second frequency more reliably and smoothly.

  The second frequency is not particularly limited as long as it is different from the first frequency and is suitable for horizontal scanning, but is preferably 10 to 40 kHz. As described above, the frequency of the second voltage V2 is set to 10 to 40 kHz, and the frequency of the first voltage V1 is set to about 60 Hz as described above, so that the movable plate 11 can be moved at a frequency suitable for drawing on the display. It can be rotated around each of two axes (X axis and Y axis) orthogonal to each other. However, the combination of the frequency of the first voltage V1 and the frequency of the second voltage V2 is not particularly limited as long as the movable plate 11 can be rotated around each of the X axis and the Y axis.

  In the present embodiment, the second frequency is the torsional resonance frequency (first torsional resonance frequency of the first vibration system having the shaft members 13a and 13b composed of the permanent magnet 20c, the movable plate 11 and the shaft members 13a and 13b as the rotation shaft ( It is set to be equal to f2). That is, the first vibration system is designed (manufactured) so that its torsional resonance frequency f2 is a frequency suitable for horizontal scanning. Thereby, the rotation angle of the movable plate 11 around the Y axis can be increased. The first frequency is the shaft member 15a, 15b composed of the permanent magnet 20c, the movable plate 11, the shaft members 13a, 13b, the permanent magnet 20a, the frame member 14, and the shaft members 15a, 15b. It is desirable that it is 1/10 or less of the torsional resonance frequency (f1) of the second vibration system with the rotation axis as. In order to drive the second vibration system in a non-resonant state (amplitude gain is 1), the first frequency needs to be set to 1/10 or less of f1. This is because driving at a frequency greater than 1/10 may cause resonance of the second vibration system.

  The second frequency is preferably set to 10 times or more of the first frequency in order to drive the second vibration system in a non-resonant state (amplitude gain is 1). If the second frequency is less than 10 times the first frequency, when the second voltage V2 is applied to the coil 30, the second vibration system also rotates, causing crosstalk of the drive signal. End up. As described above, since the first frequency is desirably one tenth or less of f1, it is desirable that the second frequency is higher than the first frequency from these relationships.

  Further, when the torsional resonance frequency of the second vibration system is f1 [Hz] and the torsional resonance frequency of the first vibration system is f2 [Hz], f1 and f2 satisfy the relationship of f2> f1. Is preferable, and it is more preferable to satisfy the relationship of f2 ≧ 10f1. As a result, the movable plate 11 can be rotated more smoothly around the Y axis at the frequency of the second voltage V2 while being rotated at the frequency of the first voltage V1. When f2 ≦ f1, there is a possibility that the first vibration system vibrates at the first frequency.

The first voltage generation unit 41 and the second voltage generation unit 42 are connected to the control unit 7 and driven based on signals from the control unit 7. A voltage superimposing unit 43 is connected to the first voltage generating unit 41 and the second voltage generating unit 42 as described above.
The voltage superimposing unit 43 includes an adder 43 a for applying a voltage to the coil 30. The adder 43 a receives the first voltage V <b> 1 from the first voltage generator 41 and receives the second voltage V <b> 2 from the second voltage generator 42, and superimposes and applies these voltages to the coil 30. It has become.

  Next, a method for driving the optical scanner 10 will be described. In the present embodiment, as described above, the frequency of the first voltage V1 is set to a value different from the torsional resonance frequency of the second vibration system, and the frequency of the second voltage V2 is the first value. Is set to be equal to and greater than the frequency of the first voltage V1 (for example, the frequency of the first voltage V1 is 60 Hz and the frequency of the second voltage V2). Is 15 kHz).

For example, the first voltage V 1 as shown in FIG. 4A and the second voltage V 2 as shown in FIG. 4B are superimposed by the voltage superimposing unit 43, and the superimposed voltage is applied to the coil 30. Apply.
Then, the vicinity of the junction between the frame member 14 and the N pole of the permanent magnet 20a and the vicinity of the junction of the movable plate 11 and the N pole of the permanent magnet 20c are attracted to the coil 30 by the first voltage V1. At the same time, a magnetic field (this magnetic field is referred to as “the magnetic field that attempts to separate the vicinity of the joint between the frame member 14 and the south pole of the permanent magnet 20a and the joint between the movable plate 11 and the south pole of the permanent magnet 20c from the coil 30”. And the vicinity of the junction between the frame member 14 and the north pole of the permanent magnet 20a and the vicinity of the junction between the movable plate 11 and the north pole of the permanent magnet 20c. In addition, a magnetic field (this magnetic field is referred to as “magnetic field A2”) that attracts the vicinity of the joint between the frame-shaped member 14 and the south pole of the permanent magnet 20a and the joint of the movable plate 11 and the south pole of the permanent magnet 20c to the coil 30. " Door is switched alternately.

  Here, as described above, the permanent magnet 20a is arranged such that each end (magnetic pole) is located in two regions divided by the X axis. That is, in the plan view of FIG. 1, the N pole of the permanent magnet 20a is located on one side of the X axis and the S pole is located on the other side. Therefore, by alternately switching between the magnetic field A1 and the magnetic field A2, the frame member 14 and the movable plate 11 rotate around the X axis at the frequency of the first voltage V1 while twisting and deforming the shaft members 15a and 15b. Move.

In the conventional example in which the axis of the permanent magnet 20a is inclined with respect to the X axis, when the magnetic field A1 and the magnetic field A2 are alternately switched, the shaft members 15a and 15b are torsionally deformed, and the top and bottom in FIG. It also curves or bends in the direction, which causes composite stress in the shaft members 15a and 15b, which may damage the shaft members 15a and 15b.
However, in this optical scanner 10, since the permanent magnet 20a is arranged so that its axis is perpendicular to the X axis, the composite stress generated in the shaft members 15a and 15b is reduced compared to the conventional example. Or generation | occurrence | production of the composite stress can be prevented, and the rotation angle around the X-axis of the movable plate 11 can be increased.

  Further, the frequency of the first voltage V1 is set to be extremely low compared to the frequency of the second voltage V2. The torsional resonance frequency of the second vibration system is designed to be lower than the torsional resonance frequency of the first vibration system (for example, 1/10 or less of the torsional resonance frequency of the first vibration system). That is, since the second vibration system is designed to vibrate more easily than the first vibration system, the frame-shaped member 14 rotates around the X axis by the first voltage V1. That is, it is possible to prevent the frame-like member 14 from rotating around the X axis by the second voltage V2.

  On the other hand, the second voltage V2 tries to attract the coil 30 near the junction between the frame member 14 and the N pole of the permanent magnet 20a and the junction between the movable plate 11 and the N pole of the permanent magnet 20c. At the same time, a magnetic field (this magnetic field is referred to as “the magnetic field that attempts to separate the vicinity of the joint between the frame member 14 and the south pole of the permanent magnet 20a and the joint between the movable plate 11 and the south pole of the permanent magnet 20c from the coil 30”. And the vicinity of the junction between the frame member 14 and the north pole of the permanent magnet 20a and the vicinity of the junction between the movable plate 11 and the north pole of the permanent magnet 20c. In addition, a magnetic field (this magnetic field is referred to as “magnetic field B2”) that attracts the coil 30 near the junction between the frame member 14 and the south pole of the permanent magnet 20a and the junction between the movable plate 11 and the south pole of the permanent magnet 20c. ") There switched alternately.

Here, as described above, the permanent magnet 20c is arranged such that each end (magnetic pole) is located in two regions divided by the Y axis. That is, in the plan view of FIG. 1, the N pole of the permanent magnet 20c is located on one side of the Y axis and the S pole is located on the other side. Therefore, by alternately switching the magnetic field B1 and the magnetic field B2, the movable plate 11 rotates around the Y axis at the frequency of the second voltage V2 while twisting and deforming the shaft members 13a and 13b.
The frequency of the second voltage V2 is equal to the torsional resonance frequency of the first vibration system. Therefore, the movable plate 11 can be rotated around the Y axis by the second voltage V2. That is, it is possible to prevent the movable plate 11 from rotating around the Y axis by the first voltage V1.

  As described above, according to the present embodiment, by applying a voltage obtained by superimposing the first voltage V1 and the second voltage V2 to the coil 30, the movable plate 11 is moved around the X axis in the first direction. While rotating at the frequency of the voltage V1, it is possible to rotate at the frequency of the second voltage V2 around the Y axis. As a result, the cost and size of the apparatus can be reduced, and the movable plate 11 can be rotated around the X axis and the Y axis. Moreover, since the permanent magnets 20a and 20c are provided in spite of a simple and small configuration, a large driving force can be obtained even if the number of coils is small. As a result, the scanning angle of the vibration system can be increased and high-speed scanning is also possible.

Further, since the permanent magnet 20a is arranged so that its axis is orthogonal to the axis of the shaft members 15a and 15b, it is possible to prevent or suppress the composite stress from being generated in the shaft members 15a and 15b. In addition, the rotation angle of the movable plate 11 around the X axis can be increased.
Further, the permanent magnet 20c is disposed such that its axis is inclined with respect to the axes of the second shaft members 13a and 13b, whereby the axis of the permanent magnet 20c and the axis of the permanent magnet 20c are not orthogonal. Magnetization can be reliably performed in a state where the hard magnetic body for the magnet 20a and the hard magnetic body for the permanent magnet 20c are installed on the frame member 14 and the movable plate 11, respectively.
In addition, by appropriately changing the first voltage V1 and the second voltage V2, desired vibration characteristics can be obtained without changing the structures of the second vibration system and the first vibration system.

  In the optical scanner 10, a permanent magnet 20a is provided on the frame-shaped member 14, a permanent magnet 20c is provided on the movable plate 11, and a coil 30 is provided on the holder 17 so as to face the permanent magnets 20a and 20c. That is, the coil 30 that is a heating element is not provided on the second vibration system and the first vibration system. Therefore, it is possible to prevent or suppress the vibration system from being bent and the resonance frequency from being changed due to heat generated from the coil 30 by energization. As a result, the optical scanner 10 can exhibit desired vibration characteristics even when used continuously for a long time.

Second Embodiment
FIG. 5 is a plan view showing a second embodiment of the optical scanner of the present invention, and FIG. 6 is a sectional view taken along line BB in FIG. In the following, for convenience of explanation, the front side in FIG. 5 is referred to as “up”, the back side in FIG. 5 is referred to as “down”, the right side is referred to as “right”, and the left side is referred to as “left”. The upper side, the lower side is called “lower”, the right side is called “right”, and the left side is called “left”.
Hereinafter, the second embodiment will be described with a focus on the differences from the first embodiment described above, and the description of the same matters will be omitted.

As shown in FIGS. 5 and 6, in the optical scanner 10 of the second embodiment, the mirror device 1 further includes a permanent magnet (second surface) provided on the lower surface of the frame-shaped member 14 (surface facing the holder 17). Permanent magnet) 20b. The permanent magnet 20b is disposed so as to be symmetrical with the permanent magnet 20a with respect to the axis of the shaft members 13a and 13b. Thereby, the movable plate 11 can be rotated more smoothly around the X axis, and the rotation angle of the movable plate 11 around the X axis can be further increased. Since the permanent magnet 20b is the same as the permanent magnet 20a, the description thereof is omitted.
The permanent magnet 20c, the movable plate 11 (light reflecting portion 12), the shaft members 13a and 13b, the permanent magnets 20a and 20b, the frame member 14, and the shaft members 15a and 15b are combined with the shaft member 15a, A second vibration system having a rotation axis 15b is configured.

<Third Embodiment>
FIG. 7 is a cross-sectional view showing a third embodiment of the optical scanner of the present invention. In the following, for convenience of explanation, the upper side in FIG. 7 is referred to as “upper”, the lower side as “lower”, the right side as “right”, and the left side as “left”.
Hereinafter, the third embodiment will be described with a focus on differences from the second embodiment described above, and description of similar matters will be omitted.

  As shown in FIG. 7, in the optical scanner 10 of the third embodiment, two concave portions (second concave portions) 141 and 142 are provided on the lower surface (the surface facing the holder 17) of the frame-like member 14 of the mirror device 1. The permanent magnets 20a and 20b are installed in the recesses 141 and 142, respectively. In the present embodiment, the central axis of the permanent magnet 20a intersects with the central axes of the shaft members 15a and 15b. That is, the vertical positions in FIG. 7 of the central axis of the permanent magnet 20a and the central axes of the shaft members 15a and 15b coincide with each other. Thereby, it can prevent or suppress that composite stress arises in shaft member 15a, 15b more reliably.

Further, a concave portion (first concave portion) 111 is formed on the lower surface (surface opposite to the light reflecting portion 12) of the movable plate 11, and the permanent magnet 20 c is installed in the concave portion 111. In the present embodiment, the central axis of the permanent magnet 20c and the central axes of the shaft members 13a and 13b intersect. That is, the vertical position in FIG. 7 of the central axis of the permanent magnet 20c and the central axis of the shaft members 13a and 13b coincide. As a result, the moment of inertia of the first vibration system can be reduced, and the apparatus can be miniaturized.
In this embodiment, the concave portion 111 is formed in the movable plate main body 110. However, the present invention is not limited to this, and a through hole is formed in the movable plate main body 110 as in the fourth embodiment to be described later. The part 12 may be configured to be the bottom of the recess 111.

<Fourth embodiment>
FIG. 8 is a cross-sectional view showing a fourth embodiment of the optical scanner of the present invention. In the following, for convenience of explanation, the upper side in FIG. 8 is referred to as “upper”, the lower side as “lower”, the right side as “right”, and the left side as “left”.
Hereinafter, the fourth embodiment will be described with a focus on differences from the second embodiment described above, and description of similar matters will be omitted.

  As shown in FIG. 8, in the optical scanner 10 according to the fourth embodiment, the frame member 14 penetrates the frame member 14 in the thickness direction on the lower surface (the surface facing the holder 17) of the frame member 14 of the mirror device 1. Two holes 143 and 144 are formed, and permanent magnets 20a and 20b are installed in the holes 143 and 144, respectively. In the present embodiment, the central axis of the permanent magnet 20a intersects with the central axes of the shaft members 15a and 15b. That is, the vertical positions in FIG. 8 of the central axis of the permanent magnet 20a and the central axes of the shaft members 15a and 15b coincide with each other. Thereby, it can prevent or suppress that composite stress arises in shaft member 15a, 15b more reliably.

Further, a concave portion 111 is formed on the lower surface of the movable plate 11 (the surface opposite to the light reflecting portion 12), and the permanent magnet 20 c is installed in the concave portion 111. In the present embodiment, the central axis of the permanent magnet 20c and the central axes of the shaft members 13a and 13b intersect. That is, the vertical positions in FIG. 8 of the central axis of the permanent magnet 20c and the central axes of the shaft members 13a and 13b coincide with each other. As a result, the moment of inertia of the first vibration system can be reduced, and the apparatus can be miniaturized.
In the present embodiment, a through hole is formed in the movable plate main body 110 and the light reflecting portion 12 is configured to be the bottom of the recess 111. However, the present invention is not limited to this, as in the third embodiment described above. Further, the movable plate main body 110 may be formed with a recess 111.

  Since the optical scanner 10 as described above includes the light reflecting section 12, for example, a laser printer, a barcode reader, a scanning confocal laser microscope, a projector, a head-up display (HUD), a head-mounted display ( It can be suitably applied to an optical scanner provided in an image forming apparatus such as an imaging display such as an HMD.

<Embodiment of Image Forming Apparatus>
FIG. 9 is a diagram schematically showing an embodiment of the image forming apparatus of the present invention.
In this embodiment, a case where the optical scanner 10 is used as an optical scanner of an imaging display will be described as an example of an image forming apparatus. The longitudinal direction of the screen S is referred to as “lateral direction”, and the direction perpendicular to the longitudinal direction is referred to as “vertical direction”. Further, the X axis, that is, the rotation center axis X is parallel to the horizontal direction of the screen S, and the Y axis, that is, the rotation center axis Y is parallel to the vertical direction of the screen S.

The image forming apparatus (projector) 9 includes a light source device (light source) 91 that emits light such as a laser, a plurality of dichroic mirrors 92, 92, 92, and an optical scanner 10.
The light source device 91 includes a red light source device 911 that emits red light, a blue light source device 912 that emits blue light, and a green light source device 913 that emits green light.
Each dichroic mirror 92 is an optical element that combines light emitted from each of the red light source device 911, the blue light source device 912, and the green light source device 913.

  Such a projector 9 combines light emitted from the light source device 91 (red light source device 911, blue light source device 912, green light source device 913) by a dichroic mirror 92 based on image information from a host computer (not shown). The combined light is two-dimensionally scanned by the optical scanner 10 to form a color image on the screen S.

During the two-dimensional scanning, the light reflected by the light reflecting portion 12 by the rotation of the movable plate 11 of the optical scanner 10 around the rotation center axis Y is scanned (main scanning) in the horizontal direction of the screen S. On the other hand, the light reflected by the light reflecting portion 12 due to the rotation of the movable plate 11 of the optical scanner 10 about the rotation center axis X is scanned (sub-scanned) in the vertical direction of the screen S.
In FIG. 9, the light synthesized by the dichroic mirror 92 is scanned two-dimensionally by the optical scanner 10, and then the light is reflected by the fixed mirror K and then an image is formed on the screen S. However, the fixed mirror K may be omitted, and the screen S may be directly irradiated with light two-dimensionally scanned by the optical scanner 10.

As described above, the mirror device, the optical scanner, and the image forming apparatus of the present invention have been described based on the illustrated embodiment. However, the present invention is not limited to this, and the configuration of each unit is an arbitrary function having the same function. It can be replaced with the configuration of Moreover, other arbitrary structures and processes may be added to the present invention.
Further, the present invention may be a combination of any two or more configurations (features) of the above embodiments.

  DESCRIPTION OF SYMBOLS 1 ... Mirror device 10 ... Optical scanner 11 ... Movable plate 110 ... Movable plate main body 111 ... Concave part 12 ... Light reflection part 13a, 13b ... Shaft member 14 ... Frame-shaped member 141, 142 ... Concave part 143, 144 ... Hole 15a, 15b ... Shaft member 16 ... support frame 17 ... holder 20a, 20b, 20c ... permanent magnet 30 ... coil 40 ... voltage applying means 41 ... first voltage generator 42 ... second voltage generator 43 ... voltage superposition unit 43a ... adder DESCRIPTION OF SYMBOLS 7 ... Control part 9 ... Projector 91 ... Light source device 911 ... Red light source device 912 ... Blue light source device 913 ... Green light source device 92 ... Dichroic mirror

Claims (8)

A movable plate provided with a light reflecting portion having light reflectivity and swingable about a first axis;
A first shaft member connected to both ends of the movable plate in the direction along the first axis;
A frame-shaped member that surrounds the movable plate, is connected to the first shaft member, and is swingable around a second axis that intersects the first axis;
A second shaft member connected to both ends of the frame-shaped member in a direction along the second axis;
Disposed on the movable plate, a first permanent magnet and one magnetic pole and the other magnetic pole is disposed across the first axis,
It is arranged in the frame-like member, comprising a second permanent magnet and one magnetic pole and the other magnetic pole is disposed across the second axis, and
In the first permanent magnet, an axis connecting the one magnetic pole and the other magnetic pole of the first permanent magnet is inclined with respect to the axis of the first shaft member and the axis of the second shaft member. Arranged,
The second permanent magnet is arranged such that an axis connecting the one magnetic pole and the other magnetic pole of the second permanent magnet is orthogonal to the axis of the second shaft member. To mirror device.   2. The mirror device according to claim 1, wherein an angle θ formed by an axis of the first shaft member and an axis of the first permanent magnet is 30 ° or more and 60 ° or less.   3. The mirror device according to claim 1, wherein the second permanent magnet is arranged in line symmetry with respect to an axis of the second shaft member. The movable plate has a first recess,
4. The mirror device according to claim 1, wherein the first permanent magnet is disposed in the first recess. 5. The frame-shaped member has a second recess or hole,
5. The mirror device according to claim 1, wherein the second permanent magnet is disposed in the second recess or the hole. Two second permanent magnets,
6. The mirror device according to claim 1, wherein the two second permanent magnets are arranged symmetrically with respect to an axis of the first shaft member. A movable plate provided with a light reflecting portion having light reflectivity and swingable about a first axis;
A first shaft member connected to both ends of the movable plate in the direction along the first axis;
A frame-shaped member that surrounds the movable plate, is connected to the first shaft member, and is swingable around a second axis that intersects the first axis;
A second shaft member connected to both ends of the frame-shaped member in a direction along the second axis;
Disposed on the movable plate, a first permanent magnet and one magnetic pole and the other magnetic pole is disposed across the first axis,
Are arranged in the frame-like member, a second permanent magnet and one magnetic pole and the other magnetic pole is disposed across the second axis,
A coil that is arranged opposite to the frame-like member and generates a magnetic field that acts on the first permanent magnet and the second permanent magnet by applying a voltage;
Voltage application means for applying a voltage to the coil,
In the first permanent magnet, an axis connecting the one magnetic pole and the other magnetic pole of the first permanent magnet is inclined with respect to the axis of the first shaft member and the axis of the second shaft member. Arranged,
The second permanent magnet is arranged such that an axis connecting the one magnetic pole and the other magnetic pole of the second permanent magnet is orthogonal to the axis of the second shaft member,
The voltage applying means includes: a first voltage generating unit that generates a first voltage having a first frequency; a second voltage generating unit that generates a second voltage having a second frequency different from the first frequency; A voltage superimposing unit that superimposes the first voltage and the second voltage, and applying the voltage superimposed by the voltage superimposing unit to the coil, thereby moving the movable plate at the first frequency. An optical scanner configured to swing around a second axis and swing around the first axis at the second frequency. A light source that emits light;
An optical scanner that scans the light from the light source,
The optical scanner is
A movable plate provided with a light reflecting portion having light reflectivity and swingable about a first axis;
A first shaft member connected to both ends of the movable plate in the direction along the first axis;
A frame-shaped member that surrounds the movable plate, is connected to the first shaft member, and is swingable around a second axis that intersects the first axis;
A second shaft member connected to both ends of the frame-shaped member in a direction along the second axis;
Disposed on the movable plate, a first permanent magnet and one magnetic pole and the other magnetic pole is disposed across the first axis,
Are arranged in the frame-like member, a second permanent magnet and one magnetic pole and the other magnetic pole is disposed across the second axis,
A coil that is arranged opposite to the frame-like member and generates a magnetic field that acts on the first permanent magnet and the second permanent magnet by applying a voltage;
Voltage application means for applying a voltage to the coil,
In the first permanent magnet, an axis connecting the one magnetic pole and the other magnetic pole of the first permanent magnet is inclined with respect to the axis of the first shaft member and the axis of the second shaft member. Arranged,
The second permanent magnet is arranged such that an axis connecting the one magnetic pole and the other magnetic pole of the second permanent magnet is orthogonal to the axis of the second shaft member,
The voltage applying means includes: a first voltage generating unit that generates a first voltage having a first frequency; a second voltage generating unit that generates a second voltage having a second frequency different from the first frequency; A voltage superimposing unit that superimposes the first voltage and the second voltage, and applying the voltage superimposed by the voltage superimposing unit to the coil, thereby moving the movable plate at the first frequency. An image forming apparatus configured to swing around a second axis and swing around the first axis at the second frequency.

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