JP2005084571A - Optical scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical scanner which is easily miniaturized, has durability and a large amplitude of oscillation. <P>SOLUTION: In the optical scanner in which an integrated structure body in which a tabular movable part 4 is supported by a torsion beam 3 in a fixing part 2 is composed of a single crystal silicon and a mirror is provided on the tabular movable part 4, a hard magnetic body 6 which is magnetized in the thickness direction of the movable part is provided on the tabular movable part 4, and an electromagnet 20 with a U-shaped core is arranged opposite to the hard magnetic material 6. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical scanner device that deflects and scans incident light, and more particularly to driving a movable portion thereof.

  As a conventional technique for deflecting and scanning light, there is a polygon mirror widely used in printers and the like. The polygon mirror uses a polygonal side surface rotated by a spindle motor as a mirror. The mirror is irradiated with a laser beam or the like, and the laser beam or the like irradiated by rotating the polygon mirror is sequentially deflected and scanned. However, the polygon mirror requires a relatively large electric power for the spindle motor, and the noise specific to the motor bearing is large.

  Galvo mirrors are often used for applications such as laser markers, laser processing machines, and laser microscopes other than printers. The galvano mirror is also driven by a motor, and the mirror can be stationary. However, since the mirror is large and assembled with mechanical parts, the apparatus becomes large and requires a large amount of power to drive it.

  Under such circumstances, an optical scanner using a micromachining technology that is small and saves power has been proposed.

  There are various driving methods for optical scanners using micromachining technology, but the electromagnetic type can increase the scanning amplitude compared to the electrostatic type and the piezoelectric type, and is being considered as an alternative to the polygon mirror.

Examples of this include those described in Patent Document 1, Patent Document 2, and Patent Document 3 below. As shown in FIG. 5, the structure described in Patent Document 1 includes a structure 53 formed of single crystal silicon, and a coil 53 and a mirror 54 on a movable portion 52 supported by a torsion beam (beam capable of torsional operation) 51. Is laid. The operating principle is that a Lorentz force is generated by passing a current through the coil 53 in a magnetic field generated by an external permanent magnet 55 to obtain a driving force. This drive system is called a moving coil system in the classification of electromagnetic actuators. As shown in FIG. 6, the structure described in Patent Document 2 includes a structure 60 formed of single crystal silicon, a mirror 62 and a soft magnetic body 63 laid on the movable portion 61, and a soft magnetic body 63 outside. The electromagnet 64 is fixed so as to face one side, and the movable portion 61 is driven by an attraction force generated by passing an electric current through the electromagnet 64. This method is close to the moving magnet method in the classification of electromagnetic actuators. In the device described in Patent Document 3, a structure 70 is formed of a semiconductor, and a movable portion 71 is provided with a magnetic film 72 magnetized in a direction perpendicular to the film surface. , 74 are fixed, and the movable portion 71 is driven by the repulsive force and the attractive force generated by the magnetic force generated in each coil and the magnetic force of the magnetic film 72 by causing a current to flow through the coils 73, 74. This method is a modification of the moving magnet method.
Japanese Patent Laid-Open No. 7-175005 (Japanese Patent No. 2722314) JP 2002-311372 A JP 2002-189187 A

  In the method described in Patent Document 1, since the lead wire to the coil is laid on the torsion beam, the wire is twisted according to the twist of the beam, which may cause a problem in durability. Moreover, it is difficult to reduce the resistance of a coil formed of a thin film, and the influence of heat generation when a current is passed must be taken into consideration. There is a problem that miniaturization is difficult if the formation of the coil is assumed.

  The method described in Patent Document 2 can solve the above-described problems in the moving coil method described in Patent Document 1, but when driven only by the suction force, the movable part is operated by applying a force to the end of the movable part. However, although the torsional movement occurs, there is a high possibility that the entire movable part is pulled toward the electromagnet and the position of the mirror is displaced, particularly when a large force is applied due to a large amplitude. Since the method described in Patent Document 3 drives the movable part by repulsive force and attractive force, the entire movable part in the method described in Patent Document 2 is pulled toward the electromagnet and the position of the mirror shifts. However, since the coil is air-centered, a large current is required for driving, and two coils having different winding directions are required.

  The present invention has been made under such circumstances, and it is an object of the present invention to provide an optical scanner device that is easy to downsize, has durability, and is capable of large amplitude.

  In order to solve the above problems, in the present invention, an optical scanner device is configured as described in the following (1) to (4).

(1) An optical scanner device in which a monolithic silicon structure having a flat movable part supported by a torsion beam inside a fixed part is made of single crystal silicon, and a mirror is provided on the movable part,
A hard magnetic material magnetized in the thickness direction of the movable part, provided in the flat movable part;
An electromagnet with a U-shaped core disposed facing the hard magnetic material;
An optical scanner device comprising:

(2) In the optical scanner device according to (1),
A container for housing the structure, wherein the electromagnet with a U-shaped core is divided into a total of three parts, one at each end of the core and one at the center of the core; An optical scanner device in which an electromagnet with a U-shaped core is formed by insert-molding the core and joining a coiled portion, which is a central portion of the core, to both end portions of the core.

(3) In the optical scanner device according to (1) or (2),
The hard scanner is an optical scanner device in which the movable part is formed by plating.

(4) In the optical scanner device according to (1) or (2),
The hard scanner is an optical scanner device formed on the movable portion by a thin film forming method such as sputtering or vacuum deposition.

  According to the present invention, since it is not necessary to form a coil in the movable part, it is easy to reduce the size, and since there is no coil in the movable part, the lead wire of the coil is not twisted by the torsion beam part and is durable. Large amplitude is possible because it is excited by an electromagnet with a letter-shaped core.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to an embodiment of an optical scanner device.

  FIG. 1 is a diagram illustrating a configuration of a structure 1 of an “optical scanner device” according to a first embodiment. As shown in the figure, the flat plate-like fixed portion 2, the movable portion 4, and the torsion beam 3 connecting the fixed portion 2 and the movable portion 4 are patterned with high precision by a semiconductor photolithography technique. In each drawing, the size is exaggerated for convenience of explanation. For example, the movable portion 4 has a size of several millimeters.

  Further, a portion of the patterned region where the hard magnetic body 6 (film magnet, see FIG. 2) is provided in advance is formed using a film generation technique such as plating, sputtering, or vapor deposition, and the shape is adjusted.

  Then, as shown in FIG. 2, a film magnet of the hard magnetic body 6 is formed on one surface of the movable portion 4 on which the film is formed.

  For the film magnet, for example, a material having a high coercive force, such as rare earth samarium cobalt-based, rare-earth-Fe-B, Fe-Pt formed by sputtering, or a cobalt-based material used in a magnetic memory device is used. As the film formation method, a chemical method or a physical method is selected in consideration of the film characteristics and cost.

  As shown in FIG. 2, an electromagnet 20 with a U-shaped core is disposed outside the structure 1 so as to face the hard magnetic body 6. The electromagnet 20 is an electromagnet with a U-shaped core 7 that is designed to have opposite polarities at both ends of the movable portion 4.

  In the electromagnet 20, the core 7 is made of a soft magnetic material, and is integrated with the single crystal silicon structure 1 together with the package 40 as shown in FIG. It is desirable to magnetize the hard magnetic body 6 immediately before assembling, but it is also possible to magnetize after assembling.

  If an electromagnet with a U-shaped core is used, only one coil is required for the electromagnet, and both cost and process can be reduced. However, it is difficult to mount a bobbin-wound coil on a U-shaped core. In order to make this easier, the U-shaped core is divided into three points, and a rod-shaped core is created and assembled to reduce costs and processes.

  Specifically, as shown in FIG. 4, two cores 41 not to be fitted with bobbin winding coils are insert-molded in advance in a plastic package 40, and the core 42 with bobbin winding coils is later attached to the end of the core 41. It is incorporated into the plastic package 40 so as to be bonded.

  In the case of an optical scanner device using single crystal silicon, a movable part and a torsion beam are often designed and used as a resonator in order to obtain a large amplitude with a small applied energy. When used as a resonator, the material physical properties of single crystal silicon are extremely stable, so the resonance frequency is determined only by the shape. The first-order resonance mode of torsion is used, but it goes without saying that a design that excludes higher-order modes that are not the purpose by simulation or the like is necessary.

  When an electric current is applied to the electromagnet 20 of the optical scanner device assembled in this way, as shown in FIG. 4 tilts in a well-balanced manner. When the application of current is stopped, the restoring force of the torsion beam 3 returns to the original position.

  If the current to be applied is an alternating current as shown in FIG. 3, the movement according to the frequency of the alternating current is repeated. When the value of the applied current is constant, the amplitude of the movable part becomes maximum at the resonance frequency as shown in FIG. 3B, and decreases as the distance from the resonance frequency increases. When the frequency is constant, the amplitude increases in proportion to the value of the applied current, as shown in FIG.

  In the configuration of the present embodiment, even if the coercive force of the film magnet (permanent magnet) provided in the movable part is slightly small, the magnetic force generated by the cored electromagnet can be increased (the magnetic flux density is 1000 to 1000 compared with the air-core coil). 10,000 times), it is easy to obtain a large amplitude. In addition, since the electromagnet exists outside the single crystal silicon structure, the generated heat does not affect the single crystal silicon structure. In the optical scanner device described in Patent Document 1, the heat generated by the coil of the movable part causes the temperature of the movable part material to increase, and the stress applied to the torsion beam changes due to the thermal expansion of the material itself, so that the resonance frequency is from the design value. It will shift. In the apparatus of this embodiment, such a problem does not occur because there is no heating element in the movable part.

  As described above, in this embodiment, since it is not necessary to form a coil in the movable part, it is easy to reduce the size, and since there is no coil in the movable part, the coil lead-in wire is not twisted by the torsion beam part and is durable. There is sex. Moreover, since it is excited by the electromagnet with the U-shaped core, the movable part can be tilted in a balanced manner, the magnetic force can be increased, and a large amplitude is possible.

  Furthermore, with one U-shaped cored electromagnet, the required reverse polarity magnetic force is obtained at both ends of the movable part, and the cost and process of manufacturing the electromagnet can be reduced. Further, since the core of the electromagnet is divided into three points and united by a package, a bobbin-wound coil can be easily attached to the U-shaped core, and the manufacturing cost and process can be reduced. A part in which a bobbin-wound coil is mounted on an I-shaped core is used in a wristwatch or the like, and can be obtained at a low cost.

(Deformation)
In the above-described embodiment, the hard magnetic body is provided over the entire surface of the flat movable body. However, the hard magnetic body may be provided only at the positions opposite to the core 41 at both ends of the movable body. The hard magnetic material may be provided on the same side as the mirror 5.

The figure which shows the structure of the structure of Example 1. The figure which shows the operation principle of Example 1. The figure which shows the characteristic of Example 1 The figure which shows how to assemble Example 1 The figure which shows the optical scanner apparatus of patent document 1 The figure which shows the optical scanner apparatus of patent document 2 The figure which shows the optical scanner apparatus of patent document 3

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Structure 2 Fixed part 3 Torsion beam 4 Movable part 5 Mirror 6 Hard magnetic body 20 Electromagnet with U-shaped core

Claims (4)

An optical scanner device comprising a monolithic silicon structure having an integral structure in which a flat movable part is supported by a torsion beam inside a fixed part, and a mirror is provided on the movable part,
A hard magnetic material magnetized in the thickness direction of the movable part, provided in the flat movable part;
An electromagnet with a U-shaped core disposed facing the hard magnetic material;
An optical scanner device comprising: The optical scanner device according to claim 1,
A container for housing the structure, wherein the electromagnet with a U-shaped core is divided into a total of three parts, one at each end of the core and one at the center of the core; An optical scanner device characterized in that an electromagnet with a U-shaped core is formed by insert-molding and joining a coiled portion, which is a central portion of the core, to both end portions of the core. The optical scanner device according to claim 1 or 2,
The optical scanner device, wherein the hard magnetic material is formed on the movable portion by plating. The optical scanner device according to claim 1 or 2,
The optical scanner device, wherein the hard magnetic material is formed on the movable part by a thin film forming method such as sputtering or vacuum deposition.

Images