JP2015210453A - Vibration element, optical scanner, image forming apparatus, image projection device, and optical pattern reading device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reliable vibration element that prevents the occurrence of flexural vibration and abnormal vibration.SOLUTION: In a stationary state, a mirror surface of a first mirror member 301 and a mirror surface of a second mirror member 302 are parallel to each other, and a first torsion beam 101 and a second torsion beam 102 are arranged side by side in the normal direction of the mirror surface of the first mirror member 301.

Description

  The present invention relates to a vibration element used for laser scanning and the like, and an optical scanning device, an image forming apparatus, an image projection apparatus, and an optical pattern reading apparatus using the vibration element.

  In recent years, a vibration element using a so-called MEMS technology using a silicon wafer has been put into practical use, and is expected to be applied to a laser beam printer, a laser projector, and the like. In addition, vibration elements using various metal materials have been proposed because they can be manufactured by a simple process compared to a vibration element using a silicon wafer and have excellent impact resistance (patents). Reference 1). These vibration elements include a vibrator configured to support a mirror with a torsion beam, and are used in consideration of a resonance frequency determined by a moment of inertia of the mirror and a spring constant of the torsion beam.

Japanese Patent Application Laid-Open No. 07-181414

  However, when a metal material is used for the mirror portion, the weight of the mirror portion increases and it is difficult to ensure the stability of the vibration characteristics. Furthermore, torsion beams must be used in a stress range below the elastic limit of the metal material. To reduce this stress, the torsion beam must be made longer. In a vibration element that supports a heavy mirror portion with a long torsion beam, the resonance frequency of the bending vibration mode becomes low, and bending vibration is likely to occur due to an external impact. Further, once bending vibration occurs, it takes time to attenuate the vibration. The bending vibration is not preferable because the scanning line is changed in the sub-scanning direction. Further, the bending vibration mode is added to the rotational vibration mode, and abnormal vibration may occur in the vibration element.

  In view of the above, an object of the present invention is to provide a highly reliable vibration element that is unlikely to generate bending vibration or abnormal vibration.

The present invention is, for example,
A rotary vibrator having a mirror member;
A plurality of torsion beams that support the rotational vibration body so as to be capable of rotational vibration;
The plurality of torsion beams are arranged side by side in the normal direction of the mirror surface of the mirror member.

Another aspect of the present invention is as follows:
A first mirror member;
A second mirror member;
An intermediate member;
A first holding member having the first mirror member fixed to the first surface and the intermediate member fixed to the second surface;
A first torsion beam coupled to the first holding member and rotatably supporting the first mirror member and the second mirror member;
A second holding member in which the intermediate member is fixed to the first surface and the second mirror member is fixed to the second surface;
A second torsion beam coupled to the second holding member and rotatably supporting the first mirror member and the second mirror member;
In a stationary state, the mirror surface of the first mirror member and the mirror surface of the second mirror member are parallel, and the first torsion beam and the second torsion beam are mirrors of the first mirror member. Provided is a vibrating element that is arranged side by side in a normal direction of a surface.

  According to the present invention, since a plurality of torsion beams are arranged side by side in the normal direction of the mirror surface, the bending rigidity of the torsion beam is increased, the resonance frequency of the bending vibration mode is improved, and the scanning line due to the bending vibration is improved. Occurrence of fluctuations and abnormal vibrations can be suppressed.

It is a figure which shows an example of an optical scanning device. It is a figure which shows an example of a vibration element. It is a figure which shows an example of a vibration element. It is a figure which shows an example of an optical scanning device. It is a figure which shows an example of a vibration element. It is a figure which shows an example of a vibration element. It is a figure which shows an example of a vibration element. It is a figure which shows an example of a vibration element. It is a figure which shows an example of a vibration element. 1 is a diagram illustrating an example of an image forming apparatus. It is a figure which shows an example of an image projector. It is a figure which shows an example of an optical pattern reader.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[Optical scanning device]
FIG. 1A shows an example of the optical scanning device 1. FIG. 1B shows the configuration of the vibration element 11. The vibration element 11 includes a vibration portion 21 that is a rotary vibration body, and a first torsion beam 101 and a second torsion beam 102 that are two torsion beams that support the vibration unit 21 so as to be capable of rotating vibration. The vibration element 11 employs a cantilever support structure that supports the vibration part 21 from one side. The cantilever support structure is useful for reducing the size of the vibration element 11.

  The vibration unit 21 includes a first mirror member 301, a second mirror member 302, a first holding member 201, a second holding member 202, and a magnet 601 as an intermediate member disposed therebetween. The first mirror member 301 is fixed to the first surface of the first holding member 201, and the intermediate member is fixed to the second surface. For example, an adhesive may be used for fixing each member, and welding may be used depending on the location. The first torsion beam 101 is coupled to the first holding member 201 and rotatably supports the first mirror member 301 and the second mirror member 302. The magnet 601 is fixed to the first surface of the second holding member 202, and the second mirror member 302 is fixed to the second surface. The second torsion beam 102 is coupled to the second holding member 202 and rotatably supports the first mirror member 301 and the second mirror member 302. Both the first torsion beam 101 and the second torsion beam 102 extend in the z-axis direction. The magnet 601 of the vibration element 11 may be a magnetic field generating unit such as a permanent magnet or an electromagnet. The first torsion beam 101 is coupled to the first holding member 201. The second torsion beam 102 is coupled to the second holding member 202.

  In a state where the vibration element 11 is stationary, the mirror surface of the first mirror member 301 and the mirror surface of the second mirror member 302 are substantially parallel. These mirror surfaces are parallel to the xz plane. In this stationary state, the first torsion beam 101 and the second torsion beam 102 are arranged side by side in the normal direction of the mirror surface of the first mirror member 301 (the + direction or the − direction of the y axis). The ends of the first torsion beam 101 and the second torsion beam 102 arranged in parallel are fixed to the housing of the optical scanning device 1 or the like. Therefore, the first torsion beam 101 and the second torsion beam 102 are torsionally deformed as an integral torsion beam. The direction of the vibrating part 21 (the normal direction of the mirror surface) changes due to torsional deformation, and the vibrating part 21 functions as a mirror part and performs optical scanning in the main scanning direction. Since the first torsion beam 101 and the second torsion beam 102 are arranged side by side in the normal direction of the mirror surface of the first mirror member 301 in the stationary state, the bending rigidity of the torsion beam is increased and the bending vibration mode is increased. Therefore, the fluctuation of the scanning line and the occurrence of abnormal vibration due to flexural vibration can be suppressed.

  The drive circuit 801 outputs a drive signal having a frequency close to the resonance frequency in the rotational vibration mode of the vibration element 11 to the magnetic field generation unit 701. The magnetic field generator 701 generates a magnetic field based on the drive signal. Rotational torque is generated in the magnet 601 by the magnetic field from the magnetic field generator 701, and rotational vibration is excited in the vibration element 11. The magnetic field generation unit 701 may be a permanent magnet, and a magnetic field generation unit such as a base material on which a coil pattern is formed may be disposed instead of the magnet 601. A drive signal is energized from the drive circuit 801 to the coil pattern. As a result, rotational vibration is excited in the vibration element 11.

  FIG. 1C shows an example of the first torsion beam 101 and the second torsion beam 102 having warp deformation. In a vibration element using a metal material, the center of gravity of a rotational vibration is likely to be shifted due to deformation of the material due to processing or a processing error, and this can also cause abnormal vibration. For example, such warpage deformation may occur in the manufacturing process of the first torsion beam 101 and the second torsion beam 102. However, as a result of mass production, the warp generated in the first twisted beam 101 and the warp generated in the second twisted beam 102 are often almost the same. Further, two twisted beams equal to the warp may be selected or selected in the assembly process. Therefore, the first torsion beam 101 and the second torsion beam 101 and the second torsion beam 102 are symmetric with respect to the rotational vibration axis of the vibration element 11 so that the warp of the first torsion beam 101 and the second torsion beam 102 are symmetrical. The beam 102 is arranged. That is, the warp direction of the first torsion beam 101 is the + direction of the y axis, and the warp direction of the second torsion beam 102 is the − direction of the y axis. Note that the axis of rotational vibration is parallel to the z-axis. Normally, when the torsion beam is warped, the center of gravity of the vibration part 21 is displaced from the rotational vibration axis of the torsion beam, causing abnormal vibration. In the present embodiment, since the warp of the first torsion beam 101 and the warp of the second torsion beam 102 are arranged symmetrically with respect to the axis of rotational vibration, the center of gravity shift of the vibration part 21 can be reduced.

  2A and 2B show an optical scanning device 2 having a vibration element 12 according to another embodiment. Only the differences between the vibration element 12 and the vibration element 11 will be described in detail. Both the first holding member 201 and the second holding member 202 are conductive members made of a conductive material. As shown in FIG. 2A and FIG. 2B (a), the vibration element 12 is coupled to the first holding member 201 and the third holding member 202 as compared to the vibration element 11. A fourth torsion beam 104 is added. In the stationary state, the third torsion beam 103 and the fourth torsion beam 104 are arranged side by side in the normal direction of the mirror surface of the first mirror member 301.

  The drive circuit 802 causes the first current I1 to flow through the first torsion beam 101, the first holding member 201, and the third torsion beam 103, and the second torsion beam 102, the second holding member 202, and the fourth torsion beam. A second current I2 is passed through the beam 104. FIG. 2B (b) shows an example of the energized state. When a current is passed only from the second torsion beam 102 to the fourth torsion beam 104 (I1 = 0, I2 ≠ 0), the Young's modulus of the first torsion beam 102 and the fourth torsion beam 104 is due to heat generated by energization. It decreases from E before energization to E-ΔE. At this time, the Young's modulus of the first torsion beam 101 and the third torsion beam 103 remains E. Therefore, the torsional rigidity of the first torsion beam 101 and the third torsion beam 103 becomes relatively high, and the axis of rotational vibration moves from A to A ′. This helps to bring the center of gravity of the vibration part 21 closer to the axis of rotational vibration. That is, the center of gravity of the vibration part 21 may be displaced from the rotational vibration axis of the torsion beam due to deformation of the torsion beam, processing errors of each member, or the like. Therefore, the drive circuit 802 makes it easy to align the center of gravity of the vibration part 21 and the axis of rotational vibration by providing a difference in the magnitude of the current to the two twisted beams in parallel. If the currents I1 and I2 are the same, the Young's modulus similarly changes in all the torsion beams, so that the resonance frequency of the vibration element 12 can be adjusted.

  In addition, since the vibration element 12 employs a double-sided structure, the bending rigidity is higher than that of the cantilevered support structure, and the fluctuation of the scanning line in the sub-scanning direction can be easily suppressed.

[Vibration element]
3 to 6 show other embodiments of the vibration element. In FIG. 3A and FIG. 3B, the first torsion beam 101, the second torsion beam 102, the third torsion beam 103, and the fourth torsion beam 104 are formed of a wire (conductive member). Yes. The first holding member 201 and the second holding member 202 are flat portions formed by pressing or the like at the center of the wire. The groove part 303 is formed in the 2nd surface side of the 1st mirror member 301, and the 1st holding member 201 is accommodated there. Similarly, the groove part 304 is formed in the 1st surface side of the 2nd mirror member 302, and the 2nd holding member 202 is accommodated there. The vibration element 13 is lighter in holding member than the vibration elements 11 and 12. In addition, the first mirror member 301 and the second mirror member 302, which are mass bodies, can be disposed near the axis of rotational vibration. As a result, the weight of the vibration element 13 can be reduced, and the rotational vibration of the vibration element 13 can be further stabilized. Further, since the torsion beam and the holding member can be formed from a wire rod, the manufacturing cost can be reduced, and the manufacturing is facilitated.

  FIG. 4A and FIG. 4B show an example of the vibration element 14 in which two torsion beams connected to the holding member are arranged in parallel. The first torsion beam 101 and the third torsion beam 103 are coupled to the first holding member 201 by opening a certain space in the x-axis direction. The second torsion beam 102 and the fourth torsion beam 104 are coupled to the second holding member 202 by opening a certain space in the x-axis direction. In the vibration element 14, similarly to the vibration element 12, the drive circuit 802 causes the first current I 1 to flow through the first torsion beam 101, the first holding member 201, and the third torsion beam 103, and the second torsion beam 102. The second current I2 may flow through the second holding member 202 and the fourth torsion beam 104. By changing the magnitude of the current I1 and the magnitude of the current I2, it is possible to bring the center of gravity of the vibration part 21 closer to the axis of rotational vibration. The method for controlling the currents I1 and I2 has already been described. In addition, since the vibration element 14 employs a cantilever structure, it is advantageous in terms of downsizing compared to the vibration element 12.

  In the vibration element 15 shown in FIGS. 5A and 5B, an insulating member 611 is disposed as an intermediate member of the vibration portion 21. Further, the first magnet 621 is arranged along the first torsion beam 101, the second magnet 622 is arranged along the second torsion beam 102, and the third magnet 623 is arranged along the third torsion beam 103. The fourth magnet 624 is arranged along the fourth torsion beam 104. The drive circuit 802 sends a first drive signal to the first torsion beam 101, the first holding member 201, and the third torsion beam 103. When this drive signal and the magnetic fields of the magnets 621, 622, 623, and 624 act, a torsion torque around the axis of rotational vibration is generated in the torsion beam. That is, rotational vibration is excited in the vibration element 15.

  The drive circuit 802 sends a second drive signal to the second torsion beam 102, the second holding member 202, and the fourth torsion beam 104. The second drive signal is, for example, a drive signal having a frequency different from the resonance frequency of the vibration element 15 and having an amplitude different from the amplitude of the first drive signal. This makes it possible to bring the center of gravity of the vibration unit 21 closer to the axis of rotational vibration.

  In the vibration element 15, the drive circuit 801 and the magnetic field generation unit 701 can be omitted as compared with the vibration element 12.

  6A and 6B show a vibration element 16 obtained by modifying the vibration element 14. The magnet 601 of the vibration element 14 is replaced with an insulating member 611. Further, the drive circuit 801 and the magnetic field generation unit 701 are omitted, and instead, the magnet 626 and the magnet 625 are arranged to face each other along the torsion beam. As shown in FIG. 6B, the magnet 626 and the magnet 625 are arranged side by side in the x-axis direction.

  In the vibration element 16, a drive signal is applied to the torsion beam in the same manner as the vibration element 15. That is, the drive circuit 802 causes the first drive signal to flow through the first torsion beam 101, the first holding member 201, and the third torsion beam 103. When this drive signal and the magnetic field of the magnets 625 and 626 act, a torsion torque around the axis of rotational vibration is generated in the torsion beam. That is, rotational vibration is excited in the vibration element 15. The drive circuit 802 may cause the second drive signal to flow through the second torsion beam 102, the second holding member 202, and the fourth torsion beam 104. This makes it possible to bring the center of gravity of the vibration unit 21 closer to the axis of rotational vibration. Further, the vibration element 16 can be made more compact than the vibration element 15.

  According to the present invention, since the two torsion beams are arranged side by side in the normal direction of the mirror surface, the bending rigidity of the torsion beam is increased, the resonance frequency of the bending vibration mode is improved, and scanning by bending vibration is performed. Line fluctuations and abnormal vibrations can be suppressed. In addition, even if deformation occurs during shape processing of the metal material, a plurality of torsion beams are arranged so that the deformation is symmetric with respect to the axis of rotational vibration, so that the displacement of the center of gravity of the vibration part can be suppressed. it can. Furthermore, even if a center of gravity shift occurs, applying different currents to the torsion beams changes the elastic modulus of the torsion beams to provide a difference in the spring constant, and the rotational vibration axis is set to the center of gravity. It becomes easy to match. Thereby, a highly reliable vibration element can be provided. Further, by using this vibration element, it is possible to provide a highly accurate optical scanning device that can perform stable optical scanning.

[Materials]
The material used for the torsion beam is not particularly limited as long as it is a conductive material such as a resin material mixed with carbon in addition to a metal material, but from the viewpoint of repeated durability and impact resistance, SUS301 and SUS631. A metal material such as stainless steel, a copper alloy, or a Co—Ni base alloy is preferable. Among them, age-hardening type Co—Ni based alloys such as Co—Ni—Cr—Mo alloys represented by Seiko Instruments' SPRON 510 have a particularly high fatigue limit and are suitable for the optical scanning device of the present invention in which repeated stress is applied. Used. In addition, since the Co—Ni based alloy has high heat resistance and corrosion resistance, the current and heat generated by the Co—Ni base alloy do not affect the material characteristics. Is preferred. Further, the Co—Ni base alloy has a feature that the internal friction is small, and has a high Q value when the vibration element is caused to resonate and rotationally vibrate, and there is an advantage that power consumption required for driving can be reduced. In the case of using a Co—Ni—Cr—Mo alloy, after a work hardening treatment is performed by rolling or drawing at a working rate of 50% or more, more preferably 90% or more, shape processing is performed, Age hardening treatment is performed at a temperature of about 600 ° C. The final Young's modulus and hardness can be adjusted by the processing rate and the aging heat treatment temperature and time. For the shape processing, etching processing, press processing, laser processing, wire electric discharge processing, or the like can be used. In work hardening processing and shape processing, depending on the finish, internal friction near the surface may increase and the Q value of the vibration element may decrease. In such a case, it is better to perform an etching process before age-hardening treatment, and after performing shape processing larger than the target dimension, finish shape processing is performed using a nitric acid-based etchant or the like. preferable. In addition, even when there are minute cracks or surface roughness that occur during work hardening or shape processing, problems such as a decrease in Q value and durability of the vibration element occur. In such a case, electropolishing is preferably performed before age hardening, and the surface is preferably smoothed by electropolishing using a phosphoric acid-based or ethylene glycol-based liquid.

  From the viewpoint of productivity, the conductive member is preferably made of the same material as the twisted beam and has an integral structure. However, the present invention is not limited to this, and it may be formed of a conductive material such as a metal material and joined to the torsion beam. When joining, it is preferable to use a wire rod for the torsion beam because the shape processing can be simplified, and for the purpose of improving the durability of the joint portion, a joining surface is formed by forging etc. Is preferred.

  The mirror member may be a reflection film directly formed on a conductive member, in addition to a reflection film or a reflection enhancement film formed on a substrate having good surface flatness such as a silicon wafer or thin glass. Examples of the reflective film include films of Au, Ag, Al, etc. formed by vapor deposition. Further, a reflective reflection film is formed thereon as necessary. Further, it is possible to form a mirror surface by polishing the conductive member. In this case, the mirror member is unnecessary.

  The magnet is not particularly limited, but is preferably as small and strong as possible in order to reduce the moment of inertia related to torsional vibration. Nd—Fe—B magnets and Sm—Co magnets with strong magnetism are preferable. Etc., Fe-Cr-Co-based magnets with excellent workability capable of forming small shapes are preferably used.

[Image forming apparatus]
FIG. 7 shows an image forming apparatus 7 which is an embodiment of an optical scanning device. The vibration element 10 is any one of the vibration elements 11 to 16 described above, and the configuration around the vibration unit is omitted. The light source 971 emits light whose intensity is modulated based on the drive signal output from the control circuit 970 according to the image data. The emitted light is reflected by the mirror member 301 of the vibration element 10 through the emission optical system 972, and scans on the photoconductor 975 which is an example of an image carrier. The scanned light is detected by BD sensors 973 and 974. The control circuit 970 generates and outputs a control signal for controlling the scanning angle based on detection signals output from the BD sensors 973 and 974. The control signal is fed back to the drive circuit 801 of the drive circuit 870 of the vibration element 10. As a result, the drive circuit 801 stably maintains the maximum scanning angle of the vibration element 10 at an appropriate value. A drive circuit 802 included in the drive circuit 870 outputs a control signal for controlling the mirror curvature based on the detection signal. Thereby, the beam spot diameter on the photosensitive member 975 is maintained at a substantially constant size.

  The image forming apparatus 7 using the vibrating elements 11 to 16 hardly causes fluctuations in scanning lines due to bending vibrations or abnormal vibrations of the vibrating elements, and can form an image with high accuracy by stable optical scanning.

[Image projection device]
FIG. 8A shows an image projection apparatus 8 which is an embodiment of the optical scanning apparatus. The vibration element 10 is any one of the vibration elements 11 to 16 described above. The light source device 981 including the three primary colors of RGB emits light whose intensity is modulated in accordance with a signal output from the control circuit 980 based on the image data. The light is two-dimensionally scanned by the vibration element 10 and the vertical scanning device 982 and projected onto the screen 983 as an image. The scanning speed of the vertical scanning device 982 is slower than that of the vibration element 10. For the vertical scanning device 982, for example, a galvanometer mirror that can perform positioning with high accuracy by non-resonant driving is used. Based on the control signal output from the control circuit 980, the drive circuit 801 included in the drive circuit 880 controls the scanning angle of the vibration element 10. Similarly, the scanning angle of the vertical scanning device 982 is controlled based on the output from the control circuit 980. Further, the drive circuit 802 of the drive circuit 880 outputs a mirror curvature control signal (drive signal), whereby the beam spot diameter on the screen 983 is maintained at a substantially constant size. Further, when the trapezoidal correction of the image is set through the input unit 984, the control circuit 980 changes the mirror curvature control signal in accordance with the change in the drive signal of the vertical scanning device 982. As a result, even when oblique projection is performed as shown in FIG. 8B, the focal length is increased in the scanning of the upper part of the screen, and the focal length is reduced in the lower part of the screen, so that the beam spot diameter on the screen is set to a substantially constant size. Can be maintained.

  As described above, the image projection apparatus 8 using any one of the vibration elements 11 to 16 hardly causes fluctuations in the scanning line due to bending vibration or abnormal vibration of the vibration element, and can project an image with high accuracy by stable optical scanning. It is.

[Optical pattern reader]
FIG. 9 shows an optical pattern reading device 9 which is an embodiment of the optical scanning device. The vibration element 10 is any one of the vibration elements 11 to 16. The light emitted from the light source 991 is reflected by the mirror member 301 of the vibration element 10 through the emission optical system 992, and scans the optical pattern. The reflected light whose intensity changes in accordance with the optical pattern is reflected again by the vibration element 10, collected by the detection optical system 994, and detected by the optical sensor 995. The decoder 996 binarizes the detection signal output from the optical sensor 995. Thereby, the information of the optical pattern is read. The drive circuit 890 outputs a drive signal for rotational vibration of the vibration element 10 and a mirror curvature control signal based on the signal from the control circuit 990. Thereby, the beam spot diameter is maintained at a substantially constant size on the projection surface having the optical pattern.

  The optical pattern reading device 9 using any one of the vibration elements 11 to 16 hardly causes fluctuations in the scanning line due to bending vibration or abnormal vibration of the vibration element, and enables high-precision reading by stable optical scanning.

[Summary]
As described with reference to FIGS. 1A to 6, in a stationary state, the mirror surface of the first mirror member 301 and the mirror surface of the second mirror member 302 are parallel, and the first torsion beam 101 and the second torsion beam 101 are the same. Two twisted beams 102 are arranged side by side in the normal direction of the mirror surface of the first mirror member 301. The bending rigidity of the torsion beam is increased, the resonance frequency of the bending vibration mode is improved, and fluctuations in scanning lines and abnormal vibration due to bending vibration can be suppressed.

  As described with reference to FIG. 1C, the first torsion beam 101 and the second torsion beam 102 warp symmetrically with respect to the axis of rotational vibration. Therefore, abnormal vibration is less likely to occur. The first torsion beam 101 and the second torsion beam 102 may be made of a metal material. For example, the first torsion beam 101 and the second torsion beam 102 are arranged so that the deformation is symmetric with respect to the axis of rotational vibration even when the metal material is deformed. The center of gravity deviation of the vibration part 21 is reduced.

  As described with reference to FIG. 3, the groove part 303 is formed on the second surface side of the first mirror member 301, and the first holding member 201 may be accommodated in the groove part 303. As a result, the first mirror member 301 can be easily disposed near the axis of rotational vibration, so that abnormal vibration is less likely to occur. A groove 304 may be formed on the first surface side of the second mirror member 302, and the second holding member 202 may be accommodated in the groove 304. Thereby, the same effect can be expected.

  As described with reference to FIGS. 2A, 2B, and 3 to 6, the third torsion beam 103 coupled to the first holding member 201 and the fourth torsion beam 104 coupled to the second holding member 202 May be further provided. In particular, in a stationary state, the third torsion beam 103 and the fourth torsion beam 104 may be arranged side by side in the normal direction of the mirror surface of the first mirror member 301. The bending rigidity of the torsion beam is increased, the resonance frequency of the bending vibration mode is improved, and fluctuations in scanning lines and abnormal vibration due to bending vibration can be suppressed.

  As described with reference to FIGS. 4 and 6, the first torsion beam 101 and the third torsion beam 103 cantilever-support the first holding member 201, and the second torsion beam 102 and the fourth torsion beam 102. The torsion beam 104 may support the second holding member 202 in a cantilever manner. The cantilever support structure is advantageous in terms of downsizing the vibration element.

  As described with reference to FIGS. 2, 3, and 5, the first torsion beam 101 and the third torsion beam 103 both support the first holding member 201, and the second torsion beam 102 and The fourth torsion beam 104 may support the second holding member 202 at both ends. The double-sided support structure will further contribute to the stabilization of rotational vibration compared to the cantilevered support.

  As described with reference to FIGS. 1A to 4, the intermediate member sandwiched between the first holding member 201 and the second holding member 202 may be a magnetic field generating means such as a magnet 601 or an electromagnet.

  On the other hand, as described with reference to FIGS. 5 and 6, the intermediate member may be the insulating member 611. In general, the insulating member 611 is lighter than a permanent magnet or the like. Therefore, the insulating member 611 will contribute to weight reduction of the vibration element. As the driving source of the vibration element, as described with reference to FIGS. 5 and 6, the first magnets 602 and 625 arranged along the first torsion beam 101 and the second torsion beam 102 are used. The 2nd magnets 622 and 626 arranged along the line function. The drive signal supplied to the first torsion beam 101 and the magnetic fields generated by the first magnets 602 and 625 and the second magnets 622 and 626 act to twist the first torsion beam 101 and the second torsion beam 102. Vibration occurs.

  As described with reference to FIGS. 2A to 6, by supplying a drive signal to the second torsion beam 102, the first mirror member 301, the first holding member 201, the intermediate member, the second holding member 202, and the second It becomes possible to bring the center of gravity of the vibration part having the two mirror members 302 closer to the rotational vibration axis of the vibration element. In particular, as described with reference to FIG. 2B, the first holding member 201, the second holding member 202, the first torsion beam 101, the second torsion beam 102, the third torsion beam 103, and the fourth torsion beam. 104 has conductivity, and the magnitude of the first current I1 flowing through the first torsion beam 101, the first holding member 201 and the third torsion beam 103, the second torsion beam 102, 2 The magnitude of the second current I2 flowing through the holding member 202 and the fourth torsion beam 104 is different. This makes it easier to bring the center of gravity of the vibration part 21 closer to the rotational vibration axis of the vibration element.

  The optical scanning device using the vibration elements 11 to 16 can easily realize stable light scanning. The image forming apparatus 7 using the vibration elements 11 to 16 is unlikely to cause fluctuations in scanning lines due to bending vibrations or abnormal vibrations of the vibration elements, so that high-precision image formation can be performed by stable light scanning. As described above, the image projection apparatus 8 using any one of the vibration elements 11 to 16 hardly causes fluctuations in the scanning line due to bending vibration or abnormal vibration of the vibration element, and can project an image with high accuracy by stable optical scanning. It will be. The optical pattern reading device 9 using any one of the vibration elements 11 to 16 is unlikely to cause fluctuations in the scanning line due to bending vibration or abnormal vibration of the vibration element, and can be read with high accuracy by stable optical scanning. .

  In the above-described embodiment, the vibration element having two mirror members is illustrated, but the number of mirror members may be one. In this case, the second mirror member 302 may be omitted, or may be replaced with a mass body having a mass equal to the mass of the first mirror member 301. In particular, in the latter case, the mass of the vibrating unit 21 is likely to be evenly distributed with respect to the axis of rotational vibration, and the tilting of the vibrating unit 21 in the sub-scanning direction can be easily reduced.

Claims (18)

A rotary vibrator having a mirror member;
A plurality of torsion beams that support the rotational vibration body so as to be capable of rotational vibration;
The vibration element, wherein the plurality of torsion beams are arranged side by side in a normal direction of a mirror surface of the mirror member. A first mirror member;
A second mirror member;
An intermediate member;
A first holding member having the first mirror member fixed to the first surface and the intermediate member fixed to the second surface;
A first torsion beam coupled to the first holding member and rotatably supporting the first mirror member and the second mirror member;
A second holding member in which the intermediate member is fixed to the first surface and the second mirror member is fixed to the second surface;
A second torsion beam coupled to the second holding member and rotatably supporting the first mirror member and the second mirror member;
In a stationary state, the mirror surface of the first mirror member and the mirror surface of the second mirror member are in a substantially parallel state, and the first torsion beam and the second torsion beam are the first mirror. A vibrating element that is arranged side by side in a normal direction of a mirror surface of a member.   The vibration element according to claim 2, wherein the first torsion beam and the second torsion beam warp symmetrically with respect to a rotational vibration axis.   4. The vibration element according to claim 2, wherein the first torsion beam and the second torsion beam are made of a metal material.   The vibration element according to claim 2, wherein a groove portion is formed on the second surface side of the first mirror member, and the first holding member is accommodated in the groove portion. A third torsion beam coupled to the first holding member;
A fourth torsion beam coupled to the second holding member;
6. The device according to claim 2, wherein in a stationary state, the third torsion beam and the fourth torsion beam are arranged side by side in a normal direction of a mirror surface of the first mirror member. The vibrating element according to item.   The first torsion beam and the third torsion beam cantilever-support the first holding member, and the second torsion beam and the fourth torsion beam cantilever-support the second holding member. The vibrating element according to claim 6, wherein:   The first torsion beam and the third torsion beam both support the first holding member, and the second torsion beam and the fourth torsion beam both support the second holding member. The vibrating element according to claim 6, wherein:   The vibration element according to claim 2, wherein the intermediate member is a magnetic field generation unit.   The vibrating element according to claim 9, wherein the intermediate member is a permanent magnet.   The vibrating element according to claim 2, wherein the intermediate member is an insulating member. A first magnet disposed along the first torsion beam;
A second magnet disposed along the second torsion beam;
Have
The drive signal supplied to the first torsion beam and the magnetic field generated by the first magnet and the second magnet act to generate torsional vibration in the first torsion beam and the second torsion beam. The vibrating element according to claim 11.   By supplying a drive signal to the second torsion beam, the center of gravity of the vibration part having the first mirror member, the first holding member, the intermediate member, the second holding member, and the second mirror member is obtained. The vibration element according to claim 12, wherein the vibration element is close to a rotational vibration axis of the vibration element. The first holding member, the second holding member, the first torsion beam, the second torsion beam, the third torsion beam, and the fourth torsion beam all have conductivity.
The first current flowing through the first torsion beam, the first holding member, and the third torsion beam, and the second torsion beam, the second holding member, and the fourth torsion beam. The vibration element according to claim 6, wherein the magnitude of the second current is different. It has a vibration element given in any 1 paragraph of Claims 1 thru / or 14,
The optical scanning device characterized in that the vibration element rotates and vibrates, and light is scanned by a mirror surface formed on at least one of the first mirror member of the vibration element or the second mirror member of the vibration element.   An image projection apparatus comprising the optical scanning device according to claim 15, wherein an image is projected onto a screen by light scanned by the optical scanning device.   An image forming apparatus comprising the optical scanning device according to claim 15 and an image carrier, and forming an image on the image carrier by light scanned by the optical scanning device.   An optical pattern reading device comprising the optical scanning device according to claim 15, wherein the optical pattern is read by light scanned by the optical scanning device.

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