JP2005181395A - Light deflector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact light deflector which deflects incident light and scans with the light at low power consumption. <P>SOLUTION: The light deflector is provided which is characterized by being furnished with a coil arranged on the face of a bottom face member, which is facing to an upper face member, and a flat plate-like scanning mirror on the other face side of which a thin film permanent magnet is formed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an optical deflector that deflects incident light and performs optical scanning, and more particularly to an optical deflector having a small movable mirror capable of operating with a large amplitude using electromagnetic force and an optical apparatus using the same, and more particularly. The present invention relates to an optical deflector that is smaller and consumes less power than a conventional optical deflector, and an optical apparatus using the optical deflector.

  Currently, an apparatus for deflecting and scanning a light beam such as a laser beam (hereinafter referred to as an optical deflector) is widely used in optical devices such as a laser beam printer and a barcode reader. There is a galvanometer mirror as a scanning mirror that deflects and scans laser light. The driving principle of the galvanometer mirror is that when a current is passed through a moving coil arranged in a magnetic field, an electromagnetic force is generated in relation to the current and the magnetic flux, and a torque proportional to the current is generated. Using the galvanometer principle that the movable coil rotates to an angle at which this torque and spring force are balanced, and the presence or absence of current is detected by swinging the pointer through this movable coil. A reflecting mirror is provided on the rotating shaft instead of the pointer.

  However, a galvanomirror requires a mechanically wound drive coil and a large yoke for generating a magnetic field, and there is a limit to downsizing these mechanical elements mainly because of output torque. At the same time, the size of the entire device for deflecting the light has been increased due to the space for assembling the constituent members.

As a small-sized optical deflector, a number of optical deflectors have been proposed for the purpose of solving the above problems by using a micromachining technique in which a micromachine is integrally formed on a semiconductor substrate by applying a semiconductor manufacturing technique. An example is disclosed in Patent Document 1. FIG. 6 is a perspective view showing a first embodiment of the publication. The optical deflection mirror unit 600, a permanent magnet 608, a magnetic yoke 609, and a fixing member 611 are configured. The light deflection mirror unit 600 includes a movable plate 601, an elastic member 602, a support 603, a drive coil 604, an electrode pad 605, and a mirror surface 606 as a mirror on the opposite side of the surface of the drive coil 604 where the drive coil 604 exists. It consists of and. The elastic member 602 has a torsion bar structure. When an alternating current is applied from the electrode pad 605, an X-direction current flowing in the drive coil 604 near the permanent magnet 608 and a Y-direction magnetic field generated from the permanent magnet 608 cause an interaction in the drive coil 604 near the permanent magnet 608. A Lorentz force in the Z direction is generated. If the polarities of the permanent magnets 608 on both sides are set in the same direction, the Lorentz force of the drive coil 604 near each permanent magnet 608 acts in the opposite direction, and the movable plate 601 swings around the X direction of the elastic member 602 as the central axis. If the mirror surface 606 is irradiated with light, it can be deflected and scanned.
JP-A-11-231252

  However, in order to use the above optical deflector for a video projector or a laser beam printer using a laser display, a high speed and a wide deflection angle are required. This optical deflector is suitable for the reason described below. I can't say.

  For example, if an optical deflector is used to achieve horizontal scanning with VGA resolution (number of horizontal scanning lines: 480 lines), the vertical scanning speed is set to 60 Hz, and when the beam reciprocating scanning is used, a scanning frequency of 14 kHz or more is required. It becomes.

  Further, the above optical deflector needs to be provided with a large permanent magnet, and it is necessary to further reduce the size in consideration of mounting on a portable device. Furthermore, since the portable device is premised on driving by a battery or a battery, power consumption is required to be small.

  In the optical deflector disclosed in the publication, in order to obtain a large deflection angle, the angle of rotation of the mirror may be increased. Further, the drive shaft spring may be hardened to increase the scanning speed. For this purpose, it is necessary to increase the torque acting on the mirror, and to increase the magnetic field at the mirror position. As a method therefor, it is required to make the permanent magnet and the magnetic yoke close to the mirror part or to increase the current flowing through the coil. However, in the configuration as shown in FIG. 6, the permanent magnet cannot be brought closer, and when the magnetic yoke is brought closer to the mirror part, if the mirror swings to a wide angle, the mirror part comes into contact with the mirror part, and a large angle cannot be realized. It will be. Further, increasing the current flowing through the coil increases the power consumption, and causes deformation of the mirror part due to heat generation.

Therefore, it cannot be said that the above prior art is sufficient as an optical deflector having a large deflection angle, capable of high-speed scanning, small size, and low power consumption. The present invention has been made in view of the above problems. The purpose of the present invention is to
Regarding an optical deflector that deflects incident light and performs optical scanning,
The present invention is to provide a compact optical deflector capable of performing high-speed scanning with a large deflection angle and a device using the optical deflector.

The optical deflector of the present invention that achieves such an object,
First, an upper surface member and a bottom surface member made of a soft magnetic material arranged substantially in parallel,
A side member made of a soft magnetic material that is sandwiched between the top member and the bottom member and defines a distance between the top member and the bottom member;
A coil disposed on a surface of the bottom member on the top member side;
The upper surface member is disposed on the surface of the bottom surface member, and is angularly displaced according to the magnetism generated by energizing the coil. The upper surface member side is a reflecting mirror portion, and the other surface side is magnetized in a thin film shape. And a flat plate-like scanning mirror on which a magnet is formed.

  Second, the top member, the bottom member, and the side member form a magnetic path from the top member to the bottom member via the side member.

  Third, the scanning mirror is integrally formed on a substrate with a torsion bar that is pivotally supported with respect to the substrate, and the permanent magnet is magnetized at an angle with respect to the torsion bar. It is characterized by.

  Fourth, the upper surface member has an opening so as not to obstruct the optical paths of the light incident on the scanning mirror and the light reflected by the scanning mirror.

  Fifth, the coil is a multilayer coil.

  Sixth, an optical apparatus using the optical deflector according to any one of the first to fifth.

  In the optical deflector according to the present invention, the soft magnetic material is disposed on the top surface, the side surface, and the bottom surface surrounding the coil and the scanning mirror, and the top surface, the side surface, and the bottom surface form a closed magnetic circuit, and the coil is energized. Thus, the generated magnetic field works efficiently on the permanent magnet of the scanning mirror. As a result, even if the torsion bar that supports the scanning mirror is hardened for high-speed scanning, the scanning mirror can be greatly angularly displaced with low power consumption, and there is no need to arrange a large permanent magnet. is there. As a result, it can be mounted on a portable device.

  The above are the basic components and more specific aspects of the present invention, and the details and operations thereof will be described below by typical examples. FIG. 1A is an exploded view showing a configuration of an embodiment of an optical deflector of the present invention. FIG. 1B is a top view showing the configuration of an embodiment of the optical deflector of the present invention. FIG. 1C is a view showing a cross section A-A ′ of FIG.

  In this embodiment, the torsion bar 101 is positioned in a straight line with respect to the scanning mirror 102 and supports the center of gravity of the scanning mirror on both sides. The torsion bar 101 and the scanning mirror 102 are integrally formed by removing the support substrate 103. For example, a semiconductor substrate can be used as the support substrate. Reflective mirror 104 that reflects incident light by depositing aluminum or the like on one surface of scanning mirror 102, and a rare earth permanent magnet such as SmCo (samarium cobalt), a ferrite magnet, FeCoCr, or the like on the other surface The alloy magnet 105 is formed into a thin film by sputtering or the like. The permanent magnet is magnetized at an angle with respect to the torsion bar 101.

  The coil 107 is formed on the substrate 106 on which an insulating film (not shown) is formed. The insulating film may be an oxide film formed on the thin film by sputtering or the like.

  The support substrate 103 on which the scanning mirror 102 and the torsion bar 101 are formed is bonded to an upper surface member 108 made of a soft magnetic material. The upper surface member 108 is provided with an opening 109 and does not obstruct the optical path of the incident light to the scanning mirror and the reflected light reflected by the reflecting mirror of the scanning mirror. Further, in order to avoid contact with the torsion bar 101, a recess 110 is formed in the upper surface member.

  The substrate 106 on which the coil 107 is formed is bonded to a bottom member 111 made of a soft magnetic material. The upper surface member 108 to which the support substrate 103 is bonded and the bottom surface member 111 to which the substrate 106 is fixed are arranged vertically with a frame-shaped side member 112 made of a soft magnetic material as a spacer. At this time, the alignment is performed so that the center position of the scanning mirror and the center position of the coil coincide. The height of the spacer is set so as not to disturb the angular displacement of the scanning mirror.

  In addition, as the soft magnetic material used for the top member, the bottom member, and the side member, a substrate having characteristics of high magnetic permeability and high saturation magnetic flux is used. For example, a soft magnetic substrate such as Fe—Ni (permalloy), Fe—Si, Co—Fe—B, etc., which has a low coercive force, a small residual magnetization, and a large saturation magnetization can be used. The soft magnetic substrate has a sufficient thickness and is not saturated by the magnetic field generated by the coil. As a result, the magnetic field generated by the coil works efficiently on the permanent magnets arranged on the mirror, and the mirror can be angularly displaced efficiently.

  In the optical deflector having this configuration, the top member, the side member, and the bottom member formed of a soft magnetic material form a closed magnetic path, and a magnetic field generated by energizing the coil works efficiently on the permanent magnet. As a result, even if the torsion bar that supports the scanning mirror is hardened for high-speed scanning, the scanning mirror can be greatly angularly displaced with low power consumption, and there is no need to arrange a large permanent magnet. is there. As a result, it can be mounted on a portable device.

(Example)
Hereinafter, the present invention will be described in more detail with reference to examples.

(First Example)
In this example, the optical deflector shown in FIG. 2 was designed and manufactured. FIG. 2A is an exploded view showing the configuration of this embodiment of the optical deflector of the present invention. FIG. 2B is a top view of the present embodiment. FIG. 2C is a diagram showing a cross section taken along the line AA ′ of FIG. A single crystal silicon substrate 201 having a thickness of 200 μm is used as a substrate, and this single crystal silicon substrate 201 is vertically etched using an ICP-RIE apparatus, whereby a scanning mirror 202 and a torsion bar 203 are integrally formed on the single crystal silicon substrate 201. did. An aluminum thin film is formed on one surface of the scanning mirror 202 as a reflecting mirror 204 by vapor deposition, and an SmCo thin film is formed on the other surface as a permanent magnet 205 by sputtering, and then an angle is formed with respect to the torsion bar. Magnetized. The coil 206 was formed by electroplating on a silicon substrate 207 on the surface of which a thermal oxide film was formed as an insulating film (not shown).

  The single crystal silicon substrate 201 on which the scanning mirror 202 and the torsion bar 203 are formed is bonded to an upper surface member 208 made of a soft magnetic material. The upper surface member 208 is provided with an opening 209, and does not obstruct the optical path of the incident light to the scanning mirror and the reflected light reflected by the reflecting mirror of the scanning mirror. Further, in order to avoid contact with the torsion bar 203, a recess 210 is formed in the upper surface member 208. Further, a side surface portion 211 serving as a spacer for maintaining a gap between the scanning mirror 202 and the coil 206 is integrally formed on the upper surface member 208 by machining. The silicon substrate 207 on which the coil 206 is formed is bonded to a bottom member 212 made of a soft magnetic material. Further, Fe—Ni (permalloy) was used as the soft magnetic material used for the top member 208 and the bottom member 212. Then, the side surface portion 211 of the upper surface member 208 to which the single crystal silicon substrate 201 is bonded and the bottom surface member 212 to which the silicon substrate 207 is fixed are bonded. At this time, the alignment is performed so that the center position of the scanning mirror and the center position of the coil coincide. The height of the side surface portion 211 is set so as not to disturb the angular displacement of the scanning mirror.

  In the optical deflector of this embodiment, the top member, the side member, and the bottom member formed of a soft magnetic material form a closed magnetic path, and the magnetic field generated by energizing the coil works efficiently on the permanent magnet. . As a result, even if the torsion bar that supports the scanning mirror is hardened for high-speed scanning, the scanning mirror can be angularly displaced greatly with low power consumption, and it is not necessary to arrange a large permanent magnet, thereby reducing the size. Became possible. As a result, it can be mounted on portable devices.

(Second embodiment)
In this embodiment, the optical deflector shown in FIG. 3 is designed and manufactured. A scanning mirror, a torsion bar, and a coil were formed by the same method as in the first embodiment. The same applies to the bottom member using the soft magnetic material. The U-shaped upper surface member 301 was formed by machining FeNi (permalloy). In addition, an opening 302 and a recess 303 are formed in the upper surface member 301 as in the first embodiment. The arrangement of the scanning mirror and the coil is the same as in the first embodiment. The side surface portion 304 of the upper surface member 301 serves as a spacer for maintaining a gap between the scanning mirror 202 and the coil 206.

  In the optical deflector of this embodiment, the top member, the side member, and the bottom member formed of a soft magnetic material form a closed magnetic path, and the magnetic field generated by energizing the coil works efficiently on the permanent magnet. . As a result, even if the torsion bar that supports the scanning mirror is hardened for high-speed scanning, the scanning mirror can be angularly displaced greatly with low power consumption, and it is not necessary to arrange a large permanent magnet, thereby reducing the size. Became possible. As a result, it can be mounted on portable devices.

(Third embodiment)
In this embodiment, an optical apparatus when the optical deflector shown in the first embodiment to the second embodiment is used will be described. FIG. 4 is a diagram illustrating an example of an image display device as an optical apparatus. In FIG. 4, 401 is an optical deflector group 401 in which two optical deflectors of FIG. 2 or 3 are arranged so that the deflection directions are orthogonal to each other. In this case, the incident light is raster-scanned in the horizontal and vertical directions. Used as an optical scanner device. Reference numeral 402 denotes a laser light source. Reference numeral 403 denotes a lens or lens group, reference numeral 404 denotes a writing lens or lens group, and reference numeral 405 denotes a projection surface. The laser light incident from the laser light source 402 is subjected to predetermined intensity modulation related to the optical scanning timing, and is scanned two-dimensionally by the optical deflector group 401. The scanned laser light forms an image on the projection surface 405 by the writing lens 404.

  As a result, an optical scanner device characterized by high speed and a large scanning angle and low power consumption can be realized.

(Fourth embodiment)
In this embodiment, an optical apparatus in the case where the optical deflector shown in the first embodiment to the second embodiment is used will be described. FIG. 5 shows an example in which the optical deflector of the present invention is used in an image forming apparatus. FIG. In FIG. 5, reference numeral 501 denotes the optical deflector shown in FIG. 2 or FIG. 3. In this case, the optical deflector 501 is used as an optical scanner device that scans incident light in one dimension. Reference numeral 502 denotes a laser light source. Reference numeral 503 denotes a lens or lens group, reference numeral 504 denotes a writing lens or lens group, and reference numeral 505 denotes a photosensitive member. The laser light emitted from the laser light source is subjected to predetermined intensity modulation related to the timing of optical scanning, and is scanned one-dimensionally by the optical deflector 501. The scanned laser beam forms an image on the photosensitive member 505 by the writing lens 504. The photosensitive member 505 is uniformly charged by a charger (not shown), and an electrostatic latent image is formed by scanning the light on the photosensitive member 505. It is formed. Next, a toner image is formed on the image portion of the electrostatic latent image by a developing device (not shown), and a visible image is formed on the paper by, for example, transferring and fixing the toner image on the paper (not shown).

  As a result, an image forming apparatus characterized by high speed and a large scanning angle and low power consumption can be realized.

a is an exploded view showing an embodiment of the optical deflector of the present invention, b is a top view showing an embodiment of the optical deflector of the present invention, and c is a cross-sectional view of FIG. a is an exploded view of the first embodiment of the optical deflector of the present invention, b is a top view of the first embodiment of the optical deflector of the present invention, and c is a cross-sectional view of FIG. It is an exploded view of the 2nd Example of the optical deflector of this invention. It is a figure which shows other embodiment of the optical instrument using the optical deflector of this invention. It is the figure which used the optical deflector of this invention for the image forming apparatus. It is a figure which shows 1st Example of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Torsion bar 102 Scanning mirror 103 Support substrate 104 Reflective mirror 105 Permanent magnet 106 Substrate 107 Coil 108 Upper surface member 109 Opening 110 Recessed portion 111 Bottom surface member 112 Side surface member 201 Single crystal silicon substrate 202 Scanning mirror 203 Torsion bar 204 Reflector mirror 205 Permanent magnet 206 Coil 207 Silicon substrate 208 Upper surface member 209 Opening portion 210 Recessed portion 211 Side surface member 212 Bottom surface member 301 Upper surface member 302 Opening portion 303 Recessed portion 304 Side surface member 401 Optical deflector 402 Laser light 403 Lens 404 Writing lens group 405 Projecting surface 501 Optical deflector 502 laser 503 lens group 504 writing lens 505 photoconductor 600 light deflection mirror unit 601 movable plate 602 elastic member 603 support 604 drive Coil 605 Electrode pad 606 Mirror surface 607 Drive coil surface 608 Permanent magnet 609 Magnetic yoke 610 Magnetic yoke 611 Fixing member

Claims (6)

A top member and a bottom member made of a soft magnetic material arranged substantially in parallel;
A side member made of a soft magnetic material that is sandwiched between the top member and the bottom member and defines a distance between the top member and the bottom member;
A coil disposed on a surface of the bottom member on the top member side;
The upper surface member is disposed on the surface of the bottom surface member, and is angularly displaced according to the magnetism generated by energizing the coil. The upper surface member side is a reflecting mirror portion, and the other surface side is magnetized in a thin film shape. An optical deflector comprising: a flat plate-like scanning mirror on which a magnet is formed.   The optical deflector according to claim 1, wherein the top surface member, the bottom surface member, and the side surface member form a magnetic path from the top surface member to the bottom surface member via the side surface member.   The scanning mirror is integrally formed on a substrate with a torsion bar that is pivotally supported so as to be angularly displaceable with respect to the substrate, and the permanent magnet is magnetized at an angle with respect to the torsion bar. The optical deflector according to claim 1 or 2, characterized in that   4. The optical deflector according to claim 1, wherein the upper surface member has an opening so as not to disturb an optical path of light incident on the scanning mirror and light reflected by the scanning mirror.   5. The optical deflector according to claim 1, wherein the coil is a multilayer coil.   An optical apparatus using the optical deflector according to claim 1.

Images