JP2019015941A - Depolarization device - Google Patents

Abstract

To provide a depolarization device that makes speckle less observable with a small number of actuators.SOLUTION: A depolarization device 1 of the present invention comprises: a stationary part 11; a first moving unit 20 that is attached to the stationary part 11 movably in a first direction; an actuator 30 that vibrates the first moving unit 20 in the first direction; and a second moving unit 60 that holds a depolarization element 10 and is suspended inside the first moving unit 20 with an elastic member 50. According to the present invention, since the second moving unit 60 moves in a Y direction with respect to the stationary part 11 when a speed of the second moving unit 60 in an X direction with respect to the stationary part 11 becomes 0, the speed of the second moving unit 60 with respect to the stationary part 11 does not become completely zero, which makes speckle less observable.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a depolarizer capable of reducing speckle.

  Conventionally, laser light is often used as a light source for televisions, projectors, printers, optical exposure apparatuses, optical measuring machines, and the like. However, since laser light is generally linearly polarized light and coherent light, speckle is generated when reflected by a scattering surface. The speckle is a variation pattern of a bright region and a dark region that are generated 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. One method for eliminating speckle is to use a depolarizing element that changes incident light having a specific polarization state into non-polarized light, that is, a random polarization state.

  The depolarizing element is further vibrated to increase the speckle reduction effect. For this reason, for example, Patent Document 1 discloses a depolarization device that vibrates a depolarization element through which a laser beam passes using one actuator (voice coil motor, VCM) in one direction in the optical path of the laser beam. It is disclosed.

  Further, Patent Document 2 discloses a projector that projects light from an image forming unit that forms an image onto a projection surface, in accordance with an imaging position at which an image is formed in an optical path of light incident on the projection surface. The depolarizing element is disposed and supported using a leaf spring. The depolarizing element is vibrated using a supporting elastic member, and imparts vibration to the depolarizing element via the supporting elastic member. A projector having two sets of VCMs constituting a driving mechanism for the above is disclosed. The two sets of VCMs drive two directions intersecting each other, and the depolarizing element is movable along an elliptical locus.

JP 2012-42742 A JP 2009-109937 A

However, since the depolarization device described in Patent Document 1 drives the depolarization element only in one direction on the optical path of the laser beam, the speed of the depolarization element is instantaneously zero when the direction of vibration changes. In this case, speckle may be observed.
In the depolarizer described in Patent Document 2, the depolarizer is driven in two directions orthogonal to each other on the optical path of the laser light, but two VCMs are required. Since each VCM requires a power source, if there are two VCMs, it is expensive and difficult to downsize.
It is an object of the present invention to provide a depolarizing device in which speckles are hardly observed with a small number of actuators.

  In order to solve the above-described problems, the present invention provides a fixed portion, a first moving portion attached to the fixed portion so as to be movable in a first direction, and vibrating the first moving portion in the first direction. There is provided a depolarizing device comprising: an actuator to be held; and a second moving unit that holds the depolarizing element and is suspended inside the first moving unit via an elastic member.

  The elastic member is preferably a coil spring.

  Magnets are respectively attached to both ends in the first direction on the lower surface of the second moving part and to both ends in the first direction on the facing surface of the first moving part facing the lower surface. preferable.

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

  The actuator is preferably a voice coil motor.

  It is preferable that the first moving part is held by a leaf spring with respect to the fixed part.

  According to the present invention, it is possible to provide a depolarization apparatus that makes it difficult to observe speckles with a small number of actuators.

It is a schematic front view of the depolarizer of 1st Embodiment. It is sectional drawing of the depolarizer of 1st Embodiment. It is a figure explaining operation | movement of the depolarizing apparatus of 1st Embodiment. It is a schematic front view of the depolarizer of 2nd Embodiment.

(First embodiment)
Hereinafter, the depolarizer 1 which is 1st Embodiment of this invention is demonstrated. FIG. 1 is a schematic front view of a depolarizer 1 according to this embodiment. FIG. 2 is a sectional view of the depolarizer 1 shown in FIG. In the figure, XYZ coordinates orthogonal to each other are provided for easy explanation. The Y direction is the vertical direction, and the XZ direction is the horizontal direction.
In this embodiment, the depolarizer 1 is used for speckle reduction in a projector using laser light. However, the present invention is not limited to this, and it can be used for speckle reduction in an optical measuring machine such as a television, a printer, an optical exposure apparatus, or a confocal microscope using laser light.

The depolarization apparatus 1 includes a depolarization element 10 and is an apparatus that eliminates speckles by reflecting the laser beam L oscillated from a laser oscillator (not shown) onto the screen by the depolarization element 10. is there. In the present embodiment, the reflective depolarizing element 10 will be described. However, 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 reflective surface 10a in which a plurality of microstructures each having a spherical shape are arranged in a plurality or arranged in a random manner. The reflecting surface 10a is substantially rectangular and is disposed along the XY plane. The reflective surface 10a faces the Z direction plus side.
The laser light L incident on the reflecting surface 10a of the depolarizing element 10 is dispersed when reflected to become laser light L with reduced speckles, and the speckles are reduced in the laser light L irradiated on the screen. The depolarizer 1 of this embodiment vibrates the depolarizer 10 as described below in order to further enhance the speckle canceling effect.

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

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

A lower end 13b of a leaf spring 13 extending upward (Y direction plus side) is attached to both ends (X direction both ends) of the fixing portion 11 in the longitudinal direction. A first moving unit 20 is attached to the upper end 13 a of the leaf spring 13.
The first moving unit 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 21 a of the two side plate portions 21 protrude outward, and the protruding portion of the upper end 21 a is fixed to the upper end 13 a of the leaf spring 13. By this protrusion, a gap S is provided between the lower side of the protrusion in the two side plate portions 21 and the leaf spring 13.

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

A hall element 33 is disposed in a portion of the fixed portion 11 that faces the X-direction drive magnet 32. The hall element 33 is a position sensor that detects the displacement of the first moving unit 20 with respect to the fixed unit 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 includes a power supply unit 41, and controls a current value flowing through the coil 31 via the power supply unit 41. When a current of a predetermined value is passed through the coil 31 from the power supply unit 41, an electromagnetic force is generated by the magnetic force generated from the X-direction driving magnet 32 and the current flowing through the coil 31. By this electromagnetic force, the first moving unit 20 moves in the X direction with respect to the fixed unit 11.
The control unit 40 causes the first moving unit 20 to vibrate in the X direction by causing an alternating current to flow 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 relative to the fixed unit 11 by detecting the change in the output current of the Hall element 33 accompanying the change in the magnetic flux density.
In the present embodiment, the VCM 30 is used for the movement of the first moving unit 20 with respect to the fixed unit 11 and the Hall element 33 is used for detecting the position of the first moving unit 20 with respect to the fixed unit 11. However, other driving methods and position detection methods may be used.

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

The second moving unit 60 includes a rectangular box-shaped frame member 61, and the depolarizing element 10 is attached inside the frame member 61.
Y direction driving second magnets 62 are attached to both ends of the lower surface of the frame member 61 in the X direction. The second Y-direction driving magnet 62 of the present embodiment is a permanent magnet and is mounted so that the N pole faces downward.
As shown in FIG. 1, the Y-direction driving second magnet 62 and the Y-direction driving first magnet 24 have the X-direction centers of the fixed portion 11, the first moving portion 20, and the second moving portion 60. In a matched state, they are shifted from each other in the X direction without facing each other.

[Operation of depolarizer]
FIGS. 3A to 3C are diagrams for explaining the operation of the depolarizer 1 according to this embodiment.
FIG. 3A shows a state at the start of the operation, and the X-direction centers of the fixed unit 11 and the first moving unit 20 and the second moving unit 60 are the same as in FIG.
When the control unit 40 starts applying an alternating current such as a rectangular wave or a sine wave to the coil 31 of the VCM 30, the first moving unit 20 starts to vibrate with respect to the fixed unit 11.
FIG. 3B shows a state where the first moving unit 20 starts to vibrate and moves to the X plus side with respect to the fixed unit 11.

In the state of FIG. 3A, the gap S is provided between the leaf spring 13 and the side plate portion 21 of the first moving unit 20 as described above. If the 1st moving part 20 moves to the X plus side with respect to the fixed part 11 like FIG.3 (b), the leaf | plate spring 13 will bend. At this time, the first moving unit 20 can move with the central axis kept vertical (parallel to the Y axis) until the lower end contacts the leaf spring 13 by the gap S.
Accordingly, 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 in the X direction can be obtained.

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

  Thus, when the 2nd moving part 60 approaches one side of the 1st moving part 20, the 2nd moving part 60 will incline with respect to the 1st moving part 20, and will be in the state which the coil spring 50 extended. The second moving part 60 is pulled obliquely upward by the restoring force (elastic force) Fb of the extended coil spring 50. That is, the second moving unit 60 is applied with the restoring force Fb having the X direction component and the first Y direction upward component by the coil spring 50.

Further, in the state of FIG. 3A, the second Y-direction driving magnet 62 and the first Y-direction driving magnet 24 are not opposed to each other but are shifted in the X direction. When the second moving unit 60 approaches one side of the first moving unit 20 as in (), the Y-direction driving second magnet 62 and the Y-direction driving first magnet 24 approach each other and face each other.
When the Y-direction driving second magnet 62 and the Y-direction driving first magnet 24 face each other, the N poles face each other, so they repel each other. Due to the 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, but the speed instantaneously becomes zero when the direction is reversed. Thereafter, the direction of the speed of the second moving unit 60 is also reversed with a delay, but the speed in the X direction instantaneously becomes zero at the time of the reversal. Here, when the speed of the second moving unit 60 relative to the fixed unit 11 becomes completely zero, speckle may be observed.
However, according to the present embodiment, when the speed of the second moving unit 60 in the X direction is 0, the first Y-direction upward component of the restoring force Fb and the second Y-direction upward force Fm The second moving unit 60 has a positive speed in the Y direction.
Accordingly, the second moving unit 60 has a speed in the Y direction even when the speed in the X direction of the fixed unit 11 is 0, so that the speed with respect to the fixed unit 11 is completely zero and is stationary. Not.
Thus, in this embodiment, when the speed of the X direction with respect to the fixed part 11 of the 2nd moving part 60 becomes 0, the 2nd moving part 60 is moving to the Y direction with respect to the fixed part 11. Therefore, the speed of the second moving unit 60 relative to the fixed unit 11 is hardly completely zero, so that speckle is hardly observed.

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

(Second Embodiment)
Next, the depolarizer 101 of 2nd Embodiment of this invention is demonstrated. FIG. 4 is a schematic front view of the depolarizer 101 of this embodiment. The second embodiment differs from the first embodiment in a second magnet 162 for driving in the Y direction and a first magnet 124 for driving in the Y direction. Since other parts are the same, the same reference numerals are given and the description thereof is omitted.

Similarly to the first embodiment, the Y-direction driving second magnet 162 is attached to both ends of the lower surface of the frame member 61 in the X direction, and both ends each have an N pole and an S pole. .
The first magnet 124 for driving in the Y direction has a plurality of N poles and S poles alternately arranged on both sides in the longitudinal direction of the upper surface (Y plus surface) of the lower plate portion 23.
Then, as shown in FIG. 4, with the X direction centers of the fixed portion 11, the first moving portion 20, and the second moving portion 60 aligned, the Y direction driving second magnet 162 and the Y direction driving The first magnet 124 has N poles facing each other, S poles facing 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 Y-direction driving second magnet 162 and the Y-direction driving first magnet 124 have the N pole and the S pole facing each other. A suction force is generated.
However, when the second moving unit 60 moves further in the X direction with respect to the first moving unit 20, the N poles again face each other, the S poles face each other, and a repulsive force is generated. That is, the repulsive force and the suction force are alternately generated by the movement of the second moving unit 60 in the X direction with respect to the first moving unit 20, and the second moving unit 60 vibrates in the Y direction with respect to the first moving unit 20. To do.

Thus, in the second embodiment, even if the speed in the X direction of the second moving unit 60 becomes 0, the second moving unit 60 vibrates in the Y direction. The speed with respect to the fixed part 11 of 60 becomes completely zero and does not enter a stationary state.
Therefore, as in the first embodiment, when the speed of the second moving unit 60 in the X direction with respect to the fixed unit 11 becomes zero, the second moving unit 60 moves in the Y direction with respect to the fixed unit 11. As a result, the speed of the second moving part 60 relative to the fixed part 11 is hardly completely zero, so that speckle is hardly observed.

As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to this.
For example, in the first embodiment, the Y-direction driving second magnet 62 and the Y-direction driving first magnet are in a state where the X-direction centers of the fixed portion 11, the first moving portion 20, and the second moving portion 60 coincide. Although the magnet 24 is arranged so that the N poles face each other, the present invention is not limited to this, and the S poles may face each other.

In addition, the Y-direction driving second magnet 62 and the Y-direction driving first magnet 24 are N in a state where the X-direction centers of the fixed portion 11, the first moving portion 20, and the second moving portion 60 coincide. You may arrange | position so that a pole and a S pole may oppose.
In this case, an attractive force is generated between the second Y-direction driving magnet 62 and the first Y-direction driving magnet 24. The suction force cancels the Y-direction component of the pulling force of the coil spring 50, but the second moving unit 60 can also be driven in the Y direction by this suction force.

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

DESCRIPTION OF SYMBOLS 1,101 Depolarization apparatus 10 Depolarization element 10a Reflecting surface 11 Fixed part 13 Leaf spring 20 1st moving part 24,124 1st magnet for Y direction drive 30 VCM
31 Coil 32 X-direction Driving Magnet 40 Control Unit 41 Power Supply Unit 50 Coil Spring 60 Second Moving Unit 61 Frame Member 62, 162 Y-direction Driving Second Magnet

Claims (6)

A fixed part;
A first moving part attached to the fixed part so as to be movable in a first direction;
An actuator that vibrates the first moving part in the first direction;
A second moving unit that holds the light cancellation element and is suspended inside the first moving unit via an elastic member;
A depolarizer. The elastic member is a coil spring;
The depolarizing apparatus according to claim 1. Both ends of the first direction on the lower surface of the second moving part;
In both ends of the first direction on the facing surface of the first moving unit facing the lower surface,
Each has a magnet attached,
The depolarizing apparatus according to claim 1 or 2. Magnets having different polarities are alternately arranged between the magnets attached to both sides of the facing surface of the first moving unit,
The depolarizing apparatus according to claim 3. The actuator is a voice coil motor.
The depolarization apparatus of any one of Claim 1 to 4. The depolarizing apparatus according to claim 1, wherein the first moving unit is held by a leaf spring with respect to the fixed unit.

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