JP6943655B2 - Polarizing device - Google Patents

Description

The present invention relates to a depolarizing device capable of reducing speckle.

Conventionally, laser light is often used as a light source for televisions, projectors, printers, optical exposure devices, optical measuring instruments, and the like. However, since laser light is generally linearly polarized light and coherent light, speckle is generated when it is reflected by a scattering surface. The speckle is a fluctuation pattern between a bright region and a dark region that occurs when coherent light such as laser light interferes with each other when reflected by a scattering surface. In order to obtain a good image in each of the above devices, it is necessary to reduce this speckle. As one of the methods for eliminating the speckle, there is a method using a depolarizing element that changes incident light having a specific polarized state into unpolarized light, that is, a random polarized state.

By vibrating this depolarizing element, the speckle reduction effect is further enhanced. Therefore, for example, Patent Document 1 describes a depolarizing device that vibrates a depolarizing element through which a laser beam passes in one direction in the optical path of the laser beam by using one actuator (voice coil motor, VCM). It is disclosed.

Further, Patent Document 2 describes a projector that projects light from an image forming portion that forms an image onto a projection surface, and is aligned with an imaging position in which an image is formed in the optical path of light incident on the projection surface. It has a depolarizing element that is arranged and supported by a leaf spring, and the depolarizing element is subjected to vibration by using a supporting elastic member, and is given vibration to the depolarizing element via the supporting elastic member. A projector having two sets of VCMs constituting a drive mechanism for this is disclosed. The two sets of VCMs drive two directions intersecting each other, and the depolarizing element can move along an elliptical locus.

Japanese Unexamined Patent Publication No. 2012-42742 Japanese Unexamined Patent Publication No. 2009-109937

However, in the depolarizing device described in Patent Document 1, since the depolarizing element is driven only in one direction on the optical path of the laser beam, the speed of the depolarizing element is momentarily 0 when the direction of vibration changes. At that time, speckle may be observed.
Further, in the polarization elimination device described in Patent Document 2, the polarization elimination elements are driven in two directions orthogonal to each other on the optical path of the laser beam, but two VCMs are required. Since each VCM requires a power source, it is costly and difficult to miniaturize if there are two VCMs.
An object of the present invention is to provide a depolarizing device in which speckles are hard to be observed with a small number of actuators.

In order to solve the above problems, the present invention vibrates the fixed portion, the first moving portion movably attached to the fixed portion in the first direction, and the first moving portion in the first direction. Provided is a depolarizing device including an actuator for causing a polarization, a second moving portion that holds the depolarizing element and is hung inside the first moving portion via an elastic member.

The elastic member is preferably a coil spring.

Magnets may be attached to both ends of the first moving portion in the first direction on the lower surface of the second moving portion and both ends of the first moving portion on the facing surface facing the lower surface in the first direction. preferable.

Magnets having different polarities may be alternately arranged between the magnets attached to both sides of the facing surface of the first moving portion.

The actuator is preferably a voice coil motor.

The first moving portion is preferably held by a leaf spring with respect to the fixed portion.

According to the present invention, it is possible to provide a depolarizing device in which speckles are hard to be observed with a small number of actuators.

It is a schematic front view of the polarization elimination device of 1st Embodiment. It is sectional drawing of the polarization elimination apparatus of 1st Embodiment. It is a figure explaining the operation of the polarization elimination apparatus of 1st Embodiment. It is a schematic front view of the polarization elimination device of the 2nd Embodiment.

(First Embodiment)
Hereinafter, the depolarizing device 1 according to the first embodiment of the present invention will be described. FIG. 1 is a schematic front view of the depolarizing device 1 of the present embodiment. FIG. 2 is a cross-sectional view of the depolarizing device 1 shown in FIG. 1 excluding the control unit 40. In the figure, XYZ coordinates orthogonal to each other are provided for ease of explanation. The Y direction is the vertical direction, and the XZ direction is the horizontal direction.
In the present embodiment, the depolarization device 1 is used for reducing speckle in a projector using a laser beam. However, the present invention is not limited to this, and it can be used for speckle reduction in an optical measuring device such as a television, a printer, an optical exposure device, or a confocal microscope using a laser beam.

The depolarization device 1 is a device that includes a depolarization element 10 and eliminates speckle by reflecting the laser beam L oscillated from a laser oscillator (not shown) on the screen by the depolarization element 10. be. Although the reflective depolarizing element 10 will be described in the present embodiment, the present invention is not limited to this, and can be applied to a transmissive depolarizing element.
The depolarizing element 10 includes, for example, a reflecting surface 10a in which a plurality of microstructures each having a spherical shape are arranged in an aligned manner or a plurality of microstructures are randomly arranged. The reflecting surface 10a is substantially rectangular and is arranged along the XY plane. The reflecting surface 10a faces the plus side in the Z direction.
The laser beam L incident on the reflecting surface 10a of the depolarizing element 10 is dispersed when reflected to become the laser beam L with reduced speckle, and the laser beam L irradiated on the screen has reduced speckle. The depolarizing device 1 of the present embodiment vibrates the depolarizing element 10 as described below in order to further enhance the effect of eliminating speckle.

[Configuration of depolarizing device]
As shown in the figure, the depolarizing device 1 has a substantially rectangular shape having a predetermined thickness in the Z direction as a whole. The depolarization device 1 includes a fixed portion 11, a first moving portion 20 that can move in the X direction with respect to the fixed portion 11, and a voice coil motor (VCM, actuator) 30 that vibrates the first moving portion 20 in the X direction. The second moving unit 60, which holds the depolarizing element 10 and is driven in the two-dimensional directions of the X and Y directions by the force generated by the vibration of the first moving unit 20 in the X direction, and the VCM 30. 1 A control unit 40 that controls vibration of the moving unit 20 with respect to the fixed unit 11 is provided.

The fixed portion 11 has a rectangular parallelepiped shape and is arranged so that the longitudinal direction is along the X direction, and a coil 31 is arranged at the central portion in the longitudinal direction (central portion in the X direction) so that a current flows in the Z direction. There is. The coil 31 is, for example, a winding coil.

The lower ends 13b of the leaf spring 13 extending upward (plus side in the Y direction) are attached to both ends (both ends in the X direction) of the fixing portion 11 in the longitudinal direction. A first moving portion 20 is attached to the upper end 13a of the leaf spring 13.
The first moving portion 20 is a substantially rectangular frame member including two side plate portions 21, an upper plate portion 22, and a lower plate portion 23. The upper ends 21a of the two side plate portions 21 project outward, and the protruding portions of the upper end 21a are fixed to the upper end 13a of the leaf spring 13. Due to this protruding portion, a gap S is provided between the two side plate portions 21 below the protruding portion and the leaf spring 13.

First magnets 24 for driving in the Y direction are attached to both ends of the upper surface (the surface on the Y plus side) of the lower plate portion 23 in the longitudinal direction. The first magnet 24 for driving in the Y direction of the present embodiment is a permanent magnet, and is attached so that the north pole faces upward.
Further, a magnet 32 for driving in the X direction is attached to the center of the lower surface (the surface on the Y minus side) of the lower plate portion 23 in the longitudinal direction. The X-direction drive magnet 32 functions as a VCM 30 together with the coil 31 described above.

A Hall element 33 is arranged at a portion of the fixed portion 11 facing the X-direction driving magnet 32. The Hall element 33 is a position sensor that detects the displacement of the first moving portion 20 with respect to the fixed portion 11.
When the first moving unit 20 moves, the magnetic field formed by the X-direction driving magnet 32 moves with respect to the Hall element 33, so that the magnetic flux density with respect to the Hall element 33 changes.

The control unit 40 has a power supply unit 41 and controls the current value flowing through the coil 31 via the power supply unit 41. When a predetermined value of current is passed through the coil 31 from the power supply unit 41, an electromagnetic force is generated by the magnetic force generated by the X-direction driving magnet 32 and the current flowing through the coil 31. Due to this electromagnetic force, the first moving portion 20 moves in the X direction with respect to the fixed portion 11.
The control unit 40 causes the first moving unit 20 to vibrate in the X direction by passing an alternating current through the coil 31.
Further, the control unit 40 has a position detection unit 42. The position detection unit 42 detects the position of the first moving unit 20 with respect to the fixed unit 11 by detecting a change in the output current of the Hall element 33 due to a change in the magnetic flux density.
In the present embodiment, the VCM 30 is used to move the first moving portion 20 with respect to the fixed portion 11, and the Hall element 33 is used to detect the position of the first moving portion 20 with respect to the fixed portion 11. However, other driving methods and position detection methods may be used.

A coil spring 50 is attached as an elastic member to the center in the longitudinal direction on the lower side of the upper plate portion 22 of the first moving portion 20. A second moving portion 60 is attached to the lower end of the coil spring 50, and the second moving portion 60 is hung inside the first moving portion 20 via the coil spring 50.

The second moving portion 60 includes a rectangular box-shaped frame member 61, and the depolarizing element 10 is attached to the inside of the frame member 61.
Second magnets 62 for driving in the Y direction are attached to both ends of the lower surface of the frame member 61 in the X direction. The second magnet 62 for driving in the Y direction of the present embodiment is a permanent magnet, and is attached so that the north pole faces downward.
As shown in FIG. 1, the second magnet 62 for driving in the Y direction and the first magnet 24 for driving in the Y direction have the center of the fixed portion 11, the first moving portion 20, and the second moving portion 60 in the X direction. They are located in the same state, not facing each other, but offset in the X direction.

[Operation of depolarizing device]
3A to 3C are diagrams illustrating the operation of the depolarizing device 1 of the present embodiment.
FIG. 3A shows a state at the start of operation, and the centers of the fixed portion 11 and the first moving portion 20 and the second moving portion 60 in the X direction coincide with each other as in FIG.
When the control unit 40 starts applying an alternating current such as a square wave or a sine wave to the coil 31 of the VCM 30, the first moving unit 20 starts vibrating to the fixed unit 11.
FIG. 3B shows a state in which the first moving portion 20 starts to vibrate and moves to the X plus side with respect to the fixed portion 11.

In the state of FIG. 3A, a gap S is provided between the leaf spring 13 and the side plate portion 21 of the first moving portion 20 as described above. When the first moving portion 20 moves to the X plus side with respect to the fixed portion 11 as shown in FIG. 3B, the leaf spring 13 bends. At this time, the first moving portion 20 can move while keeping the central axis vertical (parallel to the Y axis) until the lower end abuts on the leaf spring 13 due to the gap S.
Therefore, since the distance between the X-direction driving magnet 32 and the coil 31 in the VCM 30 does not change, a stable driving force can be obtained in the X-direction.

Further, when the first moving portion 20 vibrates in the X direction, the second moving portion 60 is pulled via the coil spring 50, but vibrates later than the first moving portion 20 due to the influence of inertial force (phase difference). Occurs). Due to this delay, a state in which the second moving unit 60 is closer to one of the first moving units 20 occurs, as in (b) and (c), for example.

In this way, when the second moving portion 60 approaches one of the first moving portions 20, the second moving portion 60 is tilted with respect to the first moving portion 20, and the coil spring 50 is in a stretched state. The second moving portion 60 is pulled diagonally upward by the restoring force (elastic force) Fb of the extended coil spring 50. That is, the coil spring 50 applies a restoring force Fb having an X-direction component and a first Y-direction upward component to the second moving portion 60.

Further, in the state of FIG. 3A, the second magnet 62 for driving in the Y direction and the first magnet 24 for driving in the Y direction were not opposed to each other and were positioned so as to be displaced in the X direction. ), When the second moving portion 60 approaches one of the first moving portions 20, the second magnet 62 for driving in the Y direction and the first magnet 24 for driving in the Y direction approach each other and face each other.
When the second magnet 62 for driving in the Y direction and the first magnet 24 for driving in the Y direction face each other, the N poles face each other and therefore repel each other. Due to this repulsive force, the second moving unit 60 applies a second upward force Fm in the Y direction to the first moving unit 20.

The first moving unit 20 reverses the direction of the speed when the direction of the alternating current is reversed, and the speed becomes 0 for a moment when the direction is reversed. After that, the direction of the speed of the second moving unit 60 is also reversed with a delay, but at the time of the reversal, the speed in the X direction becomes 0 for a moment. Here, speckle may be observed when the speed of the second moving portion 60 with respect to the fixed portion 11 becomes completely zero.
However, according to the present embodiment, when the velocity of the second moving portion 60 in the X direction is 0, the above-mentioned restoring force Fb is affected by the first upward component in the Y direction and the second upward force Fm in the Y direction. , The second moving portion 60 has a speed in the positive direction in the Y direction.
Therefore, even if the speed of the second moving portion 60 in the X direction of the fixed portion 11 is 0, the second moving portion 60 has a speed in the Y direction, so that the speed with respect to the fixed portion 11 is completely 0 and is stationary. It does not become.
As described above, in the present embodiment, when the speed of the second moving portion 60 with respect to the fixed portion 11 in the X direction becomes 0, the second moving portion 60 moves in the Y direction with respect to the fixed portion 11. Therefore, the speed of the second moving portion 60 with respect to the fixed portion 11 is unlikely to be completely zero, and the speckle is difficult to be observed.

Further, since one VCM 30 can achieve two-dimensional movement of the second moving portion 60 with respect to the fixed portion 11, the cost can be reduced as compared with the case where two VCMs are used.
Further, since the gap S is provided, the distance between the X-direction driving magnet 32 and the coil 31 in the VCM 30 does not change even when the second moving portion 60 moves in the Y-axis direction. A stable driving force can be obtained in the direction.

(Second Embodiment)
Next, the depolarization device 101 of the second embodiment of the present invention will be described. FIG. 4 is a schematic front view of the depolarizing device 101 of the present embodiment. The second embodiment differs from the first embodiment in the Y-direction driving second magnet 162 and the Y-direction driving first magnet 124. Since the other parts are the same, the same reference numerals are given and the description thereof will be omitted.

The second magnet 162 for driving in the Y direction is attached to both ends of the lower surface of the frame member 61 in the X direction as in the first embodiment, but both ends have N poles and S poles, respectively. ..
In the Y-direction driving first magnet 124, a plurality of N poles and S poles are alternately arranged on both sides in the longitudinal direction of the upper surface (the surface on the Y plus side) of the lower plate portion 23.
Then, as shown in FIG. 4, in a state where the centers of the fixed portion 11, the first moving portion 20, and the second moving portion 60 in the X direction coincide with each other, the second magnet 162 for driving in the Y direction and the second magnet 162 for driving in the Y direction are used. The north poles of the first magnet 124 face each other, the south poles face each other, and a repulsive force is generated.

When the second moving unit 60 moves in the X direction with respect to the first moving unit 20, the north pole and the south pole of the second magnet 162 for driving in the Y direction and the first magnet 124 for driving in the Y direction face each other. Suction power is generated.
However, when the second moving unit 60 further moves in the X direction with respect to the first moving unit 20, the N poles face each other and the S poles face each other, and a repulsive force is generated. That is, due to the movement of the second moving portion 60 with respect to the first moving portion 20 in the X direction, a repulsive force and a suction force are alternately generated, and the second moving portion 60 vibrates in the Y direction with respect to the first moving portion 20. do.

As described above, in the second embodiment, even when the speed of the second moving unit 60 in the X direction becomes 0, the second moving unit 60 vibrates in the Y direction, so that the second moving unit 60 The speed of the 60 with respect to the fixed portion 11 becomes completely 0 and does not become a stationary state.
Therefore, as in the first embodiment, when the speed of the second moving portion 60 with respect to the fixed portion 11 in the X direction becomes 0, the second moving portion 60 moves in the Y direction with respect to the fixed portion 11. Therefore, the speed of the second moving portion 60 with respect to the fixed portion 11 is unlikely to be completely zero, so that the speckle is difficult to be observed.

Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto.
For example, in the first embodiment, the second magnet 62 for driving in the Y direction and the first magnet for driving in the Y direction are aligned with each other in the X direction of the fixed portion 11, the first moving portion 20, and the second moving portion 60. The magnets 24 are arranged so that the north poles face each other, but the present invention is not limited to this, and the south poles may face each other.

Further, in a state where the centers of the fixed portion 11, the first moving portion 20, and the second moving portion 60 in the X direction coincide with each other, the second magnet 62 for driving in the Y direction and the first magnet 24 for driving in the Y direction are N. It may be arranged so that the pole and the S pole face each other.
In this case, an attractive force is generated between the second magnet 62 for driving in the Y direction and the first magnet 24 for driving in the Y direction. The suction force cancels out the Y-direction component of the tensile force of the coil spring 50, and the second moving portion 60 can also be driven in the Y-direction by this suction force.

Further, even when the second magnet 62 for driving in the Y direction and the first magnet 24 for driving in the Y direction are not provided, the second movement is performed only by the first upward component of the restoring force Fb of the coil spring 50 in the Y direction. The unit 60 can be driven in the Y direction.

1,101 Depolarizing device 10 Depolarizing element 10a Reflective surface 11 Fixed part 13 Leaf spring 20 1st moving part 24,124 1st magnet for driving in Y direction 30 VCM
31 Coil 32 X-direction drive magnet 40 Control unit 41 Power supply unit 50 Coil spring 60 Second moving unit 61 Frame member 62,162 Y-direction drive second magnet

Claims (6)

Fixed part and
A first moving portion that is movably attached to the fixed portion in the first direction,
An actuator that vibrates the first moving portion in the first direction,
While holding the depolarizing element, it is provided with a second moving portion that hangs down via an elastic member inside the first moving portion.
The second moving portion is a depolarizing device that swings due to inertia due to the first moving portion vibrating in the first direction. Fixed part and
A first moving portion that is movably attached to the fixed portion in the first direction,
An actuator that vibrates the first moving portion in the first direction,
In addition to holding the light-eliminating element, it is provided with a second moving portion that hangs down via an elastic member inside the first moving portion.
The elastic member is
The upper end is attached to the first moving portion, and the second moving portion is attached to the lower end.
When the first moving portion moves in the first direction, the upper end moves in the first direction together with the first moving portion, but the lower end moves due to the inertial force of the second moving portion. At the same time as the first moving part, it does not move in the first direction, so it is in an extended state.
By pulling the second moving portion by a restoring force having a first directional component and a second directional component orthogonal to the first directional component generated by the stretched state, the second moving portion is moved. It vibrates with a phase difference with respect to the movement of the first moving part.
Depolarization device. The elastic member is a coil spring.
The depolarizing device according to claim 1 or 2. The second moving portion includes a magnet attached to the lower surface of the second moving portion and a magnet.
Due to the repulsion of the first moving portion with the magnet attached to the facing surface facing the lower surface,
Swing in the second direction orthogonal to the first direction
The depolarizing device according to any one of claims 1 to 3. The actuator is a voice coil motor.
The depolarizing device according to any one of claims 1 to 4. One end of the first moving portion is attached to the fixed portion via a spring member.
The depolarizing device according to any one of claims 1 to 5 , wherein a driving force is generated by the actuator at the other end to vibrate.

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