KR101030847B1 - Method for producing oscillator device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oscillator device such as an optical deflector capable of adjusting the inertial moment or the center-of-gravity position of an oscillation part within a relatively large range at a relatively high speed.SOLUTION: The oscillator device includes an oscillation part, elastic supports 305 and 306, and a support 301, and the oscillation part is supported to oscillate around an oscillation axis 304 by the elastic supports. The oscillation part includes movable elements 302 and 320 having projected parts 303 and 321 for adjusting the mass of the oscillation part. The projected parts project from the movable elements in a direction parallel to the oscillation axis, and formed to be cut at any places in the projecting direction. The sectional areas of the projected parts to the oscillation axis as a normal are constant in the direction of the oscillation axis.

Description

Manufacturing method of vibrator device {METHOD FOR PRODUCING OSCILLATOR DEVICE}

The present invention provides a vibrator device having a movable element supported for vibrating motion, an optical deflector having such a vibrator device, such as an optical device such as an image forming apparatus or a display device using such an optical deflector, and a vibrator device. It is about how to. The optical deflector of the present invention can be suitably used, for example, in a projection display in which an image is projected on the basis of a deflection scanning of light, an image forming apparatus such as a laser beam printer or a digital copier having an electrophotographic process.

As such an optical deflector, various kinds of optical scanning systems or optical scanning apparatuses in which a movable element having a reflective surface is sinusoidally oscillated for deflecting light have been proposed. An optical scanning system having an optical deflector that sinusoidally vibrates based on resonance phenomena is as follows in comparison with a scanning optical system using a rotating polygon mirror (polygon mirror).

That is, the optical deflector can be made quite small in size, has low power consumption, and in particular, such an optical deflector made of Si single crystal and manufactured by a semiconductor process has theoretically no metal fatigue and has excellent durability.

As described above, in the optical deflector based on the resonance phenomenon, the frequency of the natural vibration mode as a target is predetermined for the desired driving frequency. There are several good suggestions for the same manufacturing method.

Japanese Laid-Open Patent Publication No. 2002-40355 uses a planar galvano mirror including a movable plate having a reflective surface and a coil and elastically supported to vibrate with respect to the torsion axis, and the galvano mirror is movable. A method having a mass load formed at opposite ends of a plate is disclosed. The laser beam is projected onto the mass load to remove its mass, thereby adjusting the moment of inertia. This achieves the desired frequency.

Japanese Laid-Open Patent Publication No. 2004-219889 discloses a method in which a movable plate is typically coated by a mass piece such as a resin, and the frequency is adjusted based on the same principle as described above.

[Documentation information of the prior art]

[Document 1] Japanese Patent Laid-Open No. 2002-40355

[Document 2] Japanese Patent Laid-Open No. 2004-219889

In the above-described method, if a large amount of adjustment has to be made, it takes a lot of time to make the adjustment. In addition, according to the adjustment principle used in these methods, it is very difficult to adjust frequency and center of gravity quickly and simultaneously.

According to an aspect of the present invention, these inconveniences can be eliminated by a method of manufacturing a vibrator device having a vibrating member, an elastic support and a support member, the vibrating member being elastically supported by the elastic support to vibrate about an oscillation axis. Supported. The method includes forming a vibrating member having a mass adjusting member for adjusting the mass of the movable element and the vibrating member while forming a gap between the movable member and a part of the mass adjusting member; The mass adjusting member is irradiated with a laser beam to partially remove the material of the mass adjusting member adjacent to the void, and the removed material includes a portion of the mass adjusting member which is not irradiated by the laser beam.

According to another aspect of the present invention, there is provided a method of manufacturing a vibrator device having a vibrating member, an elastic support portion and a support member, the vibrating member being elastically supported by the elastic support portion to vibrate about an oscillation axis, The method includes forming a vibrating member with a movable element having a protrusion to adjust the mass of the vibrating member, the protrusion extending from the movable element in a direction parallel to the vibration axis; Projecting a laser beam at the cutting position of the protrusion to partially remove the movable element, and comprising a protrusion portion in the range from the cutting position of the protrusion with the portion not irradiated by the laser beam to the tip end; The removal amount by laser beam projection is characterized by being adjusted by controlling the cutting position.

According to another aspect of the present invention, there is provided a method of manufacturing a vibrator device having a vibrating member, an elastic support portion and a support member, the vibrating member being elastically supported by the elastic support portion to vibrate about an oscillation axis, The method includes forming a vibrating member having a movable element having a plurality of protrusions for adjusting the mass of the vibrating member, the protrusions being disposed on opposite sides of the vibration axis; Cutting at least one of the protrusions along the cutting line to partially remove the movable element, and comprising a protrusion portion in the range from the cutting line of the protrusion to the tip end; The position of the cutting line is characterized in that it is controlled to adjust the offset moment of the center of gravity of the vibrating member and the moment of inertia of the vibrating member.

According to still another aspect of the present invention, there is provided a vibrator device including a vibrating member, an elastic support and a support member; The vibration member is elastically supported by the elastic support to vibrate about a vibration axis; The vibrating member has a mass adjusting member for adjusting the mass of the movable member and the vibrating member; A void is formed between the movable element and a part of the mass adjusting member.

According to still another aspect of the present invention, there is provided a vibrator device including a vibrating member, an elastic support and a support member; The vibration member is elastically supported by the elastic support to vibrate about a vibration axis; The vibrating member includes a movable element having a protrusion for adjusting the mass of the vibrating member; The protrusion extends from the movable element in a direction parallel to the oscillation axis; The cross-sectional area of the protrusion along the plane perpendicular to the vibration axis is constant in the vibration axis direction.

According to another aspect of the present invention there is provided a vibrator device comprising a vibration system, drive means configured to drive the vibration system; The vibration system comprises a first vibration member, a first elastic support, a second vibration member, a second elastic support and a support member; The first vibrating member includes a first movable element having a protrusion for adjusting the mass of the first vibrating member; The second vibrating member includes a second movable element having a protrusion for adjusting the mass of the second vibrating member; In each of the first and second movable elements, the projections extend from the movable elements in a direction parallel to the vibration axis, and the cross-sectional area of the projections along the plane perpendicular to the vibration axis is constant in the vibration axis direction; The first movable element is elastically supported by the second movable element through the first elastic support to vibrate about a vibration axis; The second movable element is elastically supported by the support member through the second elastic support to vibrate about an oscillation axis; The vibration system has at least two natural vibration modes with different frequencies.

According to another aspect of the present invention, there is provided a vibrator device comprising a vibrating member, an elastic support and a support member; The vibration member is elastically supported by the elastic support to vibrate about a vibration axis; The vibrating member includes a movable element having a plurality of protrusions for adjusting the mass of the vibrating member; The protrusions are formed in pairs, each pair disposed in a symmetrical position with respect to the oscillation axis; These protrusions disposed in symmetrical positions have mutually different shapes; The center of gravity of the vibration member is located on the vibration axis.

According to another embodiment of the present invention there is provided a vibration device comprising a vibration system and drive means configured to drive the vibration system; The vibration member comprises a first vibration member, a first elastic support, a second vibration member, a second elastic support and a support member; The first vibrating member includes a first movable element having a plurality of first protrusions for adjusting the mass of the first vibrating member; The second vibrating member includes a second movable element having a plurality of second protrusions for adjusting the mass of the second vibrating member; The plurality of first protrusions and the plurality of second protrusions are respectively disposed at symmetrical positions with respect to the vibration axis; One of the plurality of first protrusions and / or the plurality of second protrusions disposed in a symmetrical position has a shape different from each other; The center of gravity of the first vibrating member and the center of gravity of the second vibrating member are located on the vibration axis; The first movable element is elastically supported by the second movable element through the first elastic support to vibrate about a vibration axis; The second movable element is elastically supported by the support member through the second elastic support to vibrate about an oscillation axis; The vibration system has at least two natural vibration modes with different frequencies.

According to yet another aspect of the present invention, there is provided an image forming apparatus comprising a light source, an optical deflector based on the vibrator device described above, and a photosensitive member, wherein the light fragrance is used to deflect light from the light source. At least part of light is incident on the photosensitive member.

According to another aspect of the invention, there is provided an image display apparatus comprising a light source, an optical deflector based on the vibrator device described above, and an image display member, wherein the optical deflector deflects light from the light source. At least part of the light is incident on the image display member.

In summary, in a vibrator device such as an optical deflector or a method of manufacturing such a vibrator device for performing light scanning, the vibrating member may comprise a movable element and a mass adjusting member, and the air gap is between the movable element and the mass adjusting member. Can be formed on. By this arrangement, a relatively large mass can be removed quickly. In addition, the movable element is formed with protrusions for mass adjustment, which ensures rapid removal of a relatively large mass. This ensures the adjustment of the moment of inertia or its center of gravity position of the vibrating member at high speed over a large adjustment range.

These and other objects, features and advantages of the present invention will become more apparent upon consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.

According to the present invention, a relatively large mass can be removed quickly, and the moment of inertia or center of gravity of the vibrating member can be adjusted at high speed over a large adjustment range.

Preferred embodiments of the present invention will be described with reference to the accompanying drawings.

One preferred embodiment of the present invention will be described below. The vibrator device according to this embodiment may have at least one vibration member provided to vibrate about a vibration axis. The vibrating member may include a movable element having a mass adjusting member to adjust its mass. The void may be formed between the movable element and the mass adjusting member. By this void, part of the mass adjusting member can be kept spaced apart from the movable element. The void may be a recess or notch formed in the movable element or the mass adjusting member.

The vibrator device may comprise a vibration system and drive means for driving the vibration system. The vibration system may include a vibration member, a support member and an elastic support as described above. The movable member can be elastically supported by the elastic support for vibration about the oscillation axis relative to the support member. The movable element may have a reflective surface (optical deflection element) to provide an optical deflector.

In the method for manufacturing the vibrator as described above, the adjustment of the frequency of the at least one natural vibration mode equal to the target frequency at the center of the vibration axis, and the adjustment and alignment of the center of gravity of the vibration member with respect to the vibration axis To perform one side, the following procedure can be performed. For example, part of the mass adjusting member on the void can be cut by the laser beam. As the shape of the portion of the mass adjusting member on the void, the portion of the mass adjusting member may extend across the void, or may partially extend over the void as a protrusion. In the latter case, once the position (distance from the vibration axis) and the mass of the protrusion are set, the position of the moment of inertia and the center of gravity achieved by cutting the protrusion (eg by cutting the base of the protrusion using a laser beam) The adjustment amount can be detected in advance. Given a plurality of voids and protrusions as described, the moment of inertia or center of gravity can be adjusted very precisely and quickly.

In particular, in this embodiment, the mass adjusting member can be provided on the movable element, which does not need to increase the surface area of the movable element. Therefore, the mass adjusting member can be provided about the vibration axis without increasing the air resistance during the vibration of the movable element.

In the method of manufacturing the vibrator device according to another embodiment of the present invention, in order to remove the material of the mass adjusting member irradiated by the laser beam to provide the vibrating member, for example, a loop shape such as a cylinder shape (closed curve shape) The laser beam can be projected onto a portion of the mass adjusting member spaced apart from the movable element, while scanningly deflecting the laser beam. Since the area of the mass adjusting member surrounded by the closed loop (this area is not irradiated by the laser beam) is spaced apart from the movable element, this is eliminated. This reduces the amount of moment of inertia generated by the removed portion from the moment of inertia of the oscillating member relative to the oscillation axis. Alternatively, due to the decrease in mass corresponding to the removed part, the center of gravity position is adjusted.

In this way, the frequency of the natural vibration mode of the vibration system or its center of gravity position can be adjusted as desired. That is, by appropriately selecting the volume and position of the portion to be removed from the mass adjusting member, the moment of inertia or center of gravity can be adjusted as desired. In particular, by properly selecting the density of the mass adjusting member (e.g., keeping the specific gravity or relative density of the mass adjusting member small), the resolution of the frequency adjusting is dependent on the resolution for positioning or the resolution for the volume to be removed. Regardless, it can be chosen as desired. In addition, because of the presence of voids, when the laser beam is projected to remove mass only along the closed curve, the portion of the mass adjusting member surrounded by the closed curve can be removed at the same time. Therefore a large mass can be removed quickly.

This ensures the adjustment of the moment of inertia or center of gravity position at a relatively large adjustment range and high speed. In addition, because of the presence of voids, only the mass adjusting member can be accurately removed by laser beam irradiation without removing any movable element material. High precision adjustment is therefore guaranteed. In other words, if there is no such void, during the laser beam irradiation, it is possible to remove the portion of the movable element directly under the mass adjusting member. The installation of voids reliably avoids this.

A vibrator device having a vibrating member arranged to vibrate about a vibrating axis may be implemented as follows. In this embodiment, the vibrating member includes a movable element with a protrusion for adjusting the mass of the vibrating member. That is, in this embodiment, the mass adjusting member is not provided separately, but rather, a part of the movable element itself can be used to serve as the mass adjusting member. For the shape of such protrusions, there may be, for example, protrusions extending in a direction parallel to the vibration axis and protrusions extending in a direction perpendicular to the vibration axis. As an alternative, the movable element may be formed in a trapezoidal shape or a spindle shape, and its acute corner portion may be used as the protrusion.

In particular, for the protrusion extending in the direction parallel to the oscillation axis, by adjusting the cutting position at which the laser light is projected, the amount of removal from the cutting position to the tip end of the protrusion can be adjusted.

In addition, according to this embodiment, the size of the laser beam processing region can be constant and small regardless of the magnitude of the removal amount. Therefore, even if the removal amount is large, heat transfer to the vibrator device can be kept small due to the laser beam processing.

In addition, by adjusting the cutting position, the resolution with respect to the removal amount can be improved. Thus, a large adjustment range and accurate resolution can be achieved at the same time. Moreover, as a cross section perpendicular to the vibration axis, the protrusions may have a uniform cross-sectional shape and may be uniform in the vibration axis direction. In that case, the moment of inertia adjustment of the vibrating member about the length from the cutting position of the projection to the tip end and the oscillation axis will be approximately proportional. Therefore, the moment of inertia can be adjusted very easily.

All protrusions may extend in a direction parallel to the oscillation axis. In that case, the instability of the displacement angle or phase of the vibration is reduced as compared with the case where the projection extends in the direction perpendicular to the vibration axis. This instability is due to the variation of the resistance applied to the vibrating member from the ambient air. In particular, for a very small sized oscillator device, such as a few mm, fluctuations in air resistance are a very serious problem, and if the device has a portion far away from the oscillation axis (large displacement speed), this becomes very significant. When all protrusions are made parallel to the oscillation axis, both scanning stability and rapid adjustment of the moment of inertia are achieved at the same time. This can be effectively achieved even when the protrusion is formed only at the position of the vibrating member farthest from the vibrating axis.

Through micromachining procedures based on semiconductor fabrication techniques, the movable elements and protrusions of the vibrating member can be manufactured monolithically. Therefore, the vibrating member having the moment of inertia adjustment mechanism can be manufactured very precisely.

The vibrator device may include a vibration system having two vibration members arranged to vibrate about a vibration axis. In this embodiment, the first vibrating member may include a first movable element having a protrusion extending in a direction parallel to the vibrating axis. Similarly, the second vibrating member may include a second movable element having a protrusion extending in a direction parallel to the vibration axis. With respect to the cross section which functions as a normal to the oscillation axis (i.e., the cross section perpendicular to the oscillation axis), the cross-sectional area of each protrusion formed on the first and second oscillation members is constant in the direction of the oscillation axis. The vibration system may have two natural vibration modes about the vibration axis. In this embodiment, the removal amount can be adjusted by adjusting the cutting positions of the protrusions of the first and second movable elements to which the laser beam is projected, respectively.

Since both the first and second vibrating members have protrusions extending in a direction parallel to the oscillation axis which is a common axis of the vibrating system, the same cutting direction can be used for the first and second movable elements. Therefore, the cutting device is simplified.

In the method of manufacturing the vibrator as described above, in order to simultaneously perform both the adjustment to make the frequency of the at least one natural vibration mode equal to the target frequency around the vibration axis, and the adjustment of the center of gravity position of the vibration member, The following procedure can be done. Some of the protrusions protruding from the movable element can be cut. For example, it can be cut using a laser beam. By adjusting the cutting position at which the laser beam is projected, the removal amount from the cutting position of the protrusion to the tip end portion can be adjusted. The plurality of protrusions may be formed in a shape that is initially symmetrical in a symmetrical position with respect to the vibration axis. Typically, these protrusions provided in pairs have different removal amounts, and thus their final shape is different.

By removing at least some of the protrusions, the moment of inertia of the vibrating member can be adjusted according to the removal amount. In addition, by the asymmetric relationship of the amount of removal of the paired protrusions, the offset distance of the center of gravity of the vibration member from the vibration axis can be adjusted at the same time. Also in this case, a similar effect achievable by removing the protrusion as described above can be obtained. In addition, since the moment of inertia, center of gravity and offset distance can all be adjusted simultaneously by using the same protrusion, the process can be done very quickly. Moreover, the number of protrusions for adjustment can be small, and therefore the moment of inertia and mass of the vibrating member can be small. Therefore, the entire vibrator device can be miniaturized. Since the air resistance applied to the vibration member during vibration is small, the vibration stability of the vibration member is remarkably improved.

An oscillator device having a vibrating member arranged to vibrate about an oscillation axis may be implemented as follows. In this embodiment, all the projections of the vibrator device can extend parallel to the vibration axis, and the cross-sectional area perpendicular to the vibration axis can be constant in the vibration axis direction. These protrusions disposed at symmetrical positions with respect to the oscillation axis may have mutually different lengths.

According to this embodiment, the sum of the removed lengths is related to the amount of adjustment of the moment of inertia, while the ratio of the removed lengths of the protrusions is related to the amount of adjustment of the offset distance of the center of gravity of the vibrating member from the vibration axis. . Therefore, for the shape to be removed from each projection, if the total amount is determined based on the amount of inertia adjustment and the ratio of removal length is determined based on the amount of offset distance adjustment, both the moment of inertia and the offset distance of the center of gravity can be adjusted simultaneously. have. Here, the amount of inertia adjustment and the total amount of the removed length are in proportional relationship. Therefore, the moment of inertia adjustment and the center of gravity offset distance adjustment can be determined very easily and precisely.

Also in this case, similar effects that can be achieved by protrusions parallel to the oscillation axis can be obtained. Again, through a microfabrication procedure based on semiconductor manufacturing techniques, the movable element and the plurality of protrusions of the vibrating member can be manufactured monolithically. Therefore, a structure is provided that enables high precision adjustment of the moment of inertia and the offset distance of the center of gravity.

A vibrator device having a vibrating member arranged to vibrate about a vibrating axis may be implemented as follows. In this embodiment, a permanent magnet can be arranged as a drive means in the movable element, so that in response to the electromagnetic force applied from the coil disposed outside the vibration system, the movable element with the magnet can be driven. In this embodiment, the permanent magnet may be disposed in the movable element, and the center of gravity of the permanent magnet may be offset from the oscillation axis. For example, due to process error, the installation position of the permanent magnet is randomly biased, resulting in an offset of the center of gravity. However, by removing at least some of the protrusions formed in the movable element in a manner similar to that described above, the center of gravity of the movable element is offset from the oscillation axis to ensure that the center of gravity offset of the permanent magnet is offset by the center of gravity offset of the movable element. Can be. That is, these offsets cancel each other out by removing at least some of the protrusions in the following manner. That is, the ratio between i) the distance from the center of gravity of the permanent magnet to the intersection between the vibrating shaft and the line segment connecting the center of gravity of the permanent magnet and the movable element, and ii) the ratio between the center of gravity of the movable element and the aforementioned intersection The protrusions can be removed so as to be approximately equal to the ratio of the reciprocal of the mass of the permanent magnets and the movable element. By this procedure, the center of gravity of the entire vibrating member can be disposed on the vibrating axis.

As described above, in the small vibrator device including the driving means based on the electromagnetic force capable of driving the vibrating member largely, the adjustment of the frequency and the adjustment of the offset distance of the center of gravity can be performed simultaneously. The magnetic properties of permanent magnets are easily degraded by heat. In view of this, the above-described embodiment, in which a larger amount of removal does not require an enlargement of the processing area, results in a lower heat transfer due to laser beam processing and a movable element with permanent magnets having good magnetic properties is obtained. Quite advantageous in

The vibrator device, which is somewhat different from the previous embodiment, may comprise a vibration system comprising two vibration members arranged to vibrate about an oscillation axis, and a drive means for driving the vibration system. In this embodiment, the first vibrating member may include a first movable element having a plurality of protrusions extending in a direction parallel to the vibrating axis. Similarly, the second vibrating member may include a second movable member having a plurality of protrusions extending in a direction parallel to the vibration axis. The vibration system may have two natural vibration modes about the vibration axis. By adjusting the cutting positions of the respective projections of the first and second movable elements on which the laser beam is projected, the removal amount of these projections can be adjusted. The same cutting direction can be used for the first and second movable elements because both the first and second vibrating members have projections extending parallel to the oscillation axis, which is a common axis of the vibration system. Therefore, the cutting device is simplified.

As described above, in an embodiment in which the vibrating member includes a movable element having a mass adjusting member for adjusting the mass and a void is formed between the movable element and the mass adjusting member, the frequency adjustment and the offset distance adjustment to the center of gravity are as follows. Can be done simultaneously. That is, the mass adjusting member can be disposed on the opposite side of the oscillation axis, and the distance of the mass adjusting member from the oscillation axis as well as the removal amount of these mass adjusting members is determined based on the moment of inertia adjustment and the offset distance adjusting amount of the center of gravity. As determined. Then, based on this determination, part of the mass adjusting member can be removed. By this procedure, frequency adjustment and center of gravity offset distance adjustment can be made simply and very precisely.

The movable element has a reflecting surface for constructing the optical deflector and can be used as an optical deflector well tuned to a desired frequency or center of gravity offset amount for image formation or image display. If the frequency of the natural vibration mode is well tuned, the device can be compact and can be driven with low power consumption since such an optical deflector can be driven by a high amplitude amplification factor. On the other hand, if the center of gravity offset amount from the vibration axis is well adjusted, the vibration axis hardly moves during scanning. Therefore, degradation of performance such as the curvature of the scanning line or the reduced reproducibility is easily avoided.

An image forming apparatus using such an optical deflector may include a light source, an optical deflector as described above, and a photosensitive member, wherein the optical deflector deflects light from the light source so that at least part of the light is incident on the photosensitive member. .

An image display apparatus using such an optical deflector includes a light source, an optical deflector as described above, and an image display member, and the optical deflector deflects light from the light source so that at least part of the light is incident on the image display member. .

In particular, the vibration system may comprise two vibration members, and the reflecting surface may be provided to the movable element of one of the vibration members to provide the light deflector. In such an embodiment, an optical deflector may be used for image formation or image display, which is well tuned in a double or triple frequency relationship and has two natural vibration modes around the oscillation axis. This optical deflector not only can be driven by a large amplitude amplification factor, but also the uniformity of the angular velocity of the optical scan is improved through the combined-wave drive based on the above-described sine wave in the frequency relationship. Is advantageous in Therefore, deformation of the reflecting surface due to fluctuations in angular velocity during vibration is easily avoided. Besides,

Since the modulation timing of the light source for light spot formation can be set without considering the nonuniformity of the angular velocity, the modulation circuit is simplified.

In addition, if the center of gravity offset amount is well adjusted, unwanted vibration fluctuations that result in couplings that hinder the independence of the two natural vibration modes of the vibration system are easily reduced. This vibration fluctuation can be reduced by reducing the amount of offset in the center of gravity and adjusting the frequencies of the two natural vibration modes in a "multiple by an integer" relationship. Since these vibration fluctuations cause a change in the angular velocity of the vibrating member about the vibration axis and cause instability of the optical scan, these should be avoided.

Next, specific embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]

1A, 1B and 2 show an optical deflector according to an embodiment of the vibrator device of the present invention. Fig. 1A is a top view of the optical deflector, and Fig. 1B is a top view of the vibration system seen from the back side of Fig. 1A. FIG. 2 is a cross-sectional view taken along the line A-A of FIG. 1A. In this embodiment, the pair of mass adjusting members 19, the reflecting surfaces 22, and the pair of voids 30 are provided in the movable element 11 to constitute the vibration member 41. The vibration system comprises such a vibration member 41, a pair of elastic supports 12 and a support member 13.

First, together with the configuration of the present embodiment, the driving principle thereof will be described with reference to these drawings. In this embodiment, the vibration system shown in Figs. 1A and 1B vibrates torsional vibration about the oscillation shaft 17 by the driving means described later. The movable element 11, the elastic support 12, and the support member 13 are integrally made from a single crystal silicon substrate by a photolithography process and an etching process according to a semiconductor manufacturing method. Thus, a very small vibration system can be produced at a relatively low cost. In addition, since the single crystal silicon has a high Young's modulus and a low density, deformation of the movable element due to its own weight is very small. Therefore, a vibration system with a high amplitude amplification factor at resonance is achieved. In this embodiment, the movable element 11 has a dimension of 3 mm in the direction perpendicular to the vibration axis 17 and a dimension of 1 mm in the direction parallel to this axis. The total length of the vibration system is about 12 mm.

The movable element 11 is elastically supported by a pair of elastic supports 12 to torsionally vibrate about the oscillation shaft 17. The pair of mass adjusting members 19 and the pair of voids 30 are disposed on opposite sides of the oscillation shaft 17.

The reflective surface 22 provided in the movable element 11 functions to deflect the light from the light source in response to the torsional vibration of the movable element 11. The reflecting surface 22 is made of aluminum and is formed by vacuum deposition. This reflective surface may be made of other materials, for example gold or copper. A protective film may be formed on the outermost surface thereof. Here, since the movable element 11 must be formed as the reflecting surface 22, its flatness during driving is particularly important. The movable element 11 of this embodiment is supported at both ends by a pair of elastic support parts (torsion springs) 12. Therefore, compared with the single spring support, deformation due to its own weight can be suppressed well, and better flatness can be maintained.

In Fig. 2, the fixing member 150 and the driving means are shown. As shown in the figure, the driving means of the present embodiment, the fixed coil 152 fixed to the fixing member 150, and the permanent magnet 151 provided on the rear surface of the movable element 11 of the vibration member 41 Include. As shown in Figs. 1B and 2, the permanent magnet 151 of the vibrating member 41 is, for example, a prism-shaped metal magnet having a length of about 2 mm and a cross-sectional dimension of 150 m × 150 m. The permanent magnet 151 has a polarization (magnetization) direction extending along its longitudinal direction and is fixed to the movable element 11 by an adhesive agent.

As shown in FIG. 2, the fixing member 150 functions to properly maintain the position of the vibration system and the permanent magnet 151 together with the position of the fixing coil 152. In response to the application of the drive AC current, the stationary coil 152 generates an alternating magnetic field in the direction of arrow H shown in FIG. Since the magnetic flux density direction of the permanent magnet 151 is the direction of the arrow B, the magnetic field generated by the fixed coil 152 generates torque about the oscillation shaft 17, thereby driving the vibration system. .

Next, the driving principle of the optical deflector according to the present embodiment will be described in more detail. For torsional vibration about the oscillation axis 17, the vibration system of the present embodiment has a natural vibration mode of frequency f ₁ . This natural vibration mode is a torsional vibration system if the moment of the vibration member 41 about the vibration axis 17 is I, and the spring constant of the pair of elastic support parts 12 around the vibration axis 17 is K. It can be embodied by calculation based on the relationship of Equation 1 below, which represents the frequency of the natural vibration mode, where √ (K / I) means “square root of (K / I)”.

[Equation 1]

f ₁ = 1 / 2π√ (K / I)

Equation 1 provides a sufficient approximation when the damping term (eg air resistance) of the vibration system is small. The damping ratio of the vibration system of this embodiment is approximately 0.003. According to the reference frequency f ₀ , which is a target drive frequency determined by the specification of the applied optical deflector, the fixed coil 152 drives the vibration system. If the reference frequency f ₀ and the frequency f ₁ coincide, the vibration system can be driven at the point where the highest amplitude amplification factor of the natural vibration mode is high.

However, due to various error factors such as material property variations and processing tolerances, for example, the frequency f ₁ may shift from the reference frequency f ₀ . Accordingly, the mass adjusting member 19 is partially removed to adjust the moment of inertia I of the vibrating member 41 of Equation 1, thereby adjusting the frequency f ₁ to match the reference frequency f ₀ . Let's do it. The mass adjusting member 19 of this embodiment is provided by adhering an aluminum flat plate to the movable element 11 as shown in Figs. 1A, 1B and 2.

As described above, the amount of adjustment of the moment of inertia can be increased or decreased based on the volume of the portion removed from the mass adjusting member 19 and the distance from the oscillation shaft 17. For example, the moment of inertia I and the spring constant K are assumed so that a predetermined error range of the frequency f ₁ is assumed and the frequency f ₁ including the error range is kept lower than the reference frequency f ₀ . Can be set. By doing so, the frequency f ₁ can be adjusted towards the reference frequency f ₀ . By way of example, the vibration amplitude of the movable element 11 can be measured while sweeping the drive frequency before partially removing the mass adjusting member 19. This may determine the appropriate amount of removal as required. Here, by appropriately setting the density of the mass adjusting member 19, the adjustment resolution with respect to the frequency f ₁ is independent of the resolution regarding the volume of the portion to be removed and its distance from the oscillation axis 17. Can be set.

In addition, in this embodiment, the mass adjusting member 19 is disposed on the surface opposite to the surface on which the permanent magnet 151 of the plate-shaped movable element 11 is mounted. This structure effectively reduces the deviation of the center of gravity of the vibration member 41 from the vibration axis 17, and reduces unnecessary vibration. In addition, by removing a part of the mass adjusting member 19, the center of gravity of the vibrating member 41 is reduced from being shifted from the vibrating shaft 17. For example, an observation laser beam may be incident on the reflecting surface 22, and the trajectory of the torsional vibration about the oscillation axis 17 may be observed by observing the scanning trajectory. Thereafter, the center of gravity deviation can be satisfactorily reduced by removing the mass adjusting member 19 to reduce unnecessary vibration.

Next, the process of partially removing the mass adjusting member 19 will be described in detail with reference to the drawings. The movable element 11 of this embodiment is formed so as to have the space | gap 30 formed by the through-hole as shown in FIG. 1B. Due to the provision of this void 30, as shown in FIG. 2, the mass adjusting member 19 has an area which is not adhered to the movable element 11. These voids 30 are formed simultaneously when the vibration system is formed by dry etching from a single crystal silicon substrate.

7A to 7C are schematic diagrams for explaining a process of partially removing the mass adjusting member 19 of this embodiment. In this embodiment, a pulsed laser is irradiated onto the portion to be processed of the mass adjusting member 19, whereby the mass is partially removed. 7A is a top view of a sample at an initial stage of laser beam processing. FIG. 7B is a top view showing a state where the process is further advanced from the state of FIG. 7A. FIG. 7C is a cross-sectional view taken along the line C-C in FIG. 7B. As shown in FIG. 7C, due to the presence of the void 30, the mass removing portion 85, which is part of the non-adhesive region of the mass adjusting member, which is not adhered to the movable element 11, can finally be removed. .

First, as shown in Fig. 7A, the processing laser beam spot 80 is scanned along the processing trajectory 82 so as to draw an arc-shaped loop (closed curve) in the direction of rotation 83. The processing laser beam spot 80 emits light at an output and pulse frequency suitable for processing the mass adjusting member 19. As shown, by the processing laser beam spot 80, the processing portion 81 along the processing trajectory 82 is formed.

FIG. 7B shows the state after the processing laser beam spot 80 has cycled an appropriate number of times along the processing trajectory 82. As shown, a through opening 84 is formed along the machining trajectory 82. Fig. 7C shows a cross section of this part. The machining laser beam spot 80 further circulates along the machining trajectory 82 and removes the periphery of the mass removal portion 85 along the arced loop. As shown in FIG. 7C, since the mass removing portion 85 is not adhered to the movable element 11 due to the presence of the void 30, it is separated and removed from the movable element 11 by the above-described process.

In the above-described process, if the diameter of the machining trajectory 82 is enlarged, a large mass can be removed at high speed. Of course, the shape of the machining trajectory 82 is not limited to the arc-shaped loop described above.

According to this embodiment as described above, due to the effect of the presence of the voids 30, a volume larger than the volume from which the laser beam is directly irradiated and removed can be removed at a high speed. This can increase the frequency adjustment range and the center of gravity position adjustment range of the natural vibration mode of the vibration system, as well as enable high speed adjustment. Further, the provision of the voids 30 makes it possible to remove only the mass adjusting member 19 by laser beam processing without removing a part of the movable element 11. As a result, adjustment of the natural vibration mode frequency and center of gravity adjustment of the vibration system can be made very precisely.

In addition, as in the present embodiment, by providing the cavity 30 which is a through hole formed in the movable element 11, the mass adjusting member 19 can have a flat plate shape. This facilitates the assembly for adhesion. The mass adjusting member 19 of the present embodiment may be made of a material such as a metal, a dielectric, or a semiconductor that absorbs a laser beam for processing.

The movable element 11 and the mass adjusting member 19 of this embodiment may have a form as shown in FIG. 3 is a cross-sectional view taken along the line A-A of FIG. 1A. Compared with the example of FIG. 2, in the structure shown in FIG. 3, the voids 30 are formed in the mass adjusting member 19. Even in this case, similar beneficial effects can be obtained with respect to mass removal using laser beam irradiation.

The vibrator device according to this embodiment of the present invention has been described with reference to an optical deflector that reflects and deflects light. However, on the basis of measuring the change in the driving frequency due to the deposition of a predetermined external mass on the movable element 11, it can be applied to a sensor for detecting the deposition amount of a predetermined substance on the surface.

In addition, in the above-described embodiment, the case in which the vibration system has one intrinsic vibration mode about the vibration axis 17 has been described, but the vibration system has a plurality of elastically supported to twist the vibration in series about the vibration axis 17. The vibration system may have a plurality of natural vibration modes. Also in this case, according to the above-described manufacturing method, the frequencies of these natural vibration modes can be adjusted respectively by adjusting the moment of inertia of each vibration member. In addition, unnecessary vibration can be satisfactorily reduced by adjusting the center of gravity of these vibration members.

Second Embodiment

4A, 4B, 5 and 6 show an optical deflector according to a second embodiment of the vibrator device of the present invention. Fig. 4A is a top view, and Fig. 4B is a top view of the vibration system seen from the back side of Fig. 4A. 5 and 6 are cross-sectional views taken along lines C-C and D-D of FIGS. 4A and 4B, respectively. In these figures, components having similar functions as in the first embodiment are designated by the same reference numerals. In the following, description of portions having functions similar to those of the first embodiment will be omitted, and only distinct features will be described in detail.

As shown in Figs. 4A and 4B, the optical deflector of this embodiment uses only one elastic support 12, and the vibration system is supported by the fixing member 150 in a cantilever structure.

In addition, in this embodiment, the mass adjusting member 19 is formed of a resin, which is disposed on the surface opposite to the surface on which the permanent magnet 151 of the plate-shaped movable element 11 is provided. As a result, it is easy to reduce the deviation of the center of gravity of the vibration member 41 from the vibration axis 17, and can reduce unnecessary vibration. That is, as shown in Fig. 5, the permanent magnet 151 and the mass adjusting member 19 are disposed on opposite sides of the movable element 11 with the oscillation shaft 17 therebetween. Therefore, the deviation of the center of gravity of the vibrating member 41 from the vibrating shaft 17 due to the provision of the mass adjusting member 19 can be effectively reduced.

The movable element 11, the elastic support part 12, and the support member 13 which comprise the vibration system of this embodiment are integrally formed by anisotropic etching of single crystal silicon using the aqueous alkali solution mentioned later. In this example, as shown in Figs. 5 and 6, the movable element 11 and the elastic support 12 have a characteristic shape surrounded by the crystal equivalent surface (surface) of single crystal silicon.

As shown in Fig. 5, the movable element 11 of this embodiment is formed by a recess 31 extending in parallel with the oscillation shaft 17. As shown in Figs. The recess 31 has an effect similar to that of the cavity 30 in the first embodiment in the process of partially removing the mass adjusting member 19 by the laser beam. For example, by selecting the distance from the vibration axis 17 and the volume of the mass portion to be removed, for example, the relationship between the removal mass and the removal moment of inertia can be changed. Therefore, while adjusting the frequency of the natural vibration mode, the center of gravity position of the vibration member 41 can be aligned with the vibration axis 17.

Further, by providing the recesses 31 as the voids, these voids can be formed only by using the flat plate member as the mass adjusting member 19, so that the assembly for adhesion is easy. In addition, since no gap is formed on the back surface spaced apart from the surface on which the concave portion 31 is formed, the entire back surface except for the region on which the permanent magnet 151 is mounted can be used as the reflecting surface.

On the other hand, as shown in Fig. 6, the elastic support portion 12 has an X-shaped cross-sectional shape surrounded by the (100) equivalent surface and the (111) equivalent surface of single crystal silicon. Therefore, the elastic support 12 has great rigidity with respect to the directions of arrows L and M of FIG. 6, but the rigidity of the elastic support 12 in the direction of the arrow N about the vibration axis 17 is relatively weak. That is, it can be easily twisted about the vibration shaft 17 as a torsion spring, and it is hard to bend in the other direction. Therefore, unnecessary vibration in the directions of the arrows L and M is effectively suppressed.

In addition, this embodiment uses only one elastic support 12, and the vibration system is supported by the fixing member 150 in a cantilever structure. Therefore, even when deformation occurs in the fixing member 150 due to a temperature change or a predetermined external force, stress is hardly transmitted from the fixing member 150 to the vibration system in the direction of the vibration axis 17. Therefore, the predetermined change of the natural vibration mode frequency caused by such a stress in the axial direction is well suppressed. In addition, even if the fixing member 150 is deformed, deformation of the vibration system hardly occurs. As a result, the center of gravity position which is adjusted to be aligned with the oscillation shaft 17 at the time of manufacture cannot be changed by temperature change or a predetermined external force, and thus unnecessary vibration is reduced regardless of such temperature change or external force.

Next, an alkaline aqueous solution etching process for the movable element 11, the elastic support 12 and the support member 13 of the present embodiment will be described. 8 and 9 show shapes in an aqueous alkali solution corresponding to the cross sections of FIGS. 5 and 6. 8 and 9, the cross-sectional shapes of (a) to (f) are shapes at corresponding timings, respectively. First, in (a), a silicon substrate 99 having a (100) equivalent surface 100 in the illustrated direction and having a protective film 101 formed thereon is used, and patterning of the protective film 101 is performed. In the present embodiment, the protective film 101 includes a silicon nitride film. The silicon nitride film can be formed using chemical vapor phase synthesis. By photolithography and dry etching, a pattern can be formed in the protective film 101 as shown in (a).

Here, as shown in Fig. 8, an opening having a width Wk is formed. 9, openings of widths Wb and Wg are formed. These widths are determined according to the angle formed by the (111) equivalent plane and the (100) equivalent plane and the thickness of the silicon substrate 99. By setting these widths appropriately, the required torsion spring constants and the dimensions of the voids can be achieved based on the specifications of the vibration system.

Next, in (b), the substrate is immersed in an aqueous alkali solution to start etching. In this example, an aqueous solution of potassium hydroxide was used. In an aqueous alkali solution such as an aqueous potassium hydroxide solution, since the etching rate of the (111) equivalent surface of single crystal silicon is slow compared to the other surface, a shape surrounded by the (111) equivalent surface can be formed satisfactorily. As the etching proceeds, the substrate is etched in the order as shown in (b) to (f). Finally, in (f), the movable element 11, the recessed part 31, the elastic support part 12, and the support member which are surrounded by the (100) equivalent plane 100 and the (111) equivalent plane 102 13) is formed. After that, the protective film 101 on both sides is removed by dry etching. Thereafter, the reflecting surface 22 is formed by vacuum deposition in the shape shown in Fig. 4A, thereby providing a vibration system.

As described above, in the present embodiment, the movable element 11, the recess 31, the elastic support 12, and the support member 13 are simultaneously formed by one alkaline aqueous solution etching. As a result, the manufacturing process is simplified and the vibration system can be manufactured at low cost.

In particular, the (111) equivalent surface of single crystal silicon has a slow etching speed, which makes it possible to precisely form the shape of the recess 31 and the elastic support 12. By precision machining of the recess 31, the moment of inertia or center of gravity of the movable element 11 can be determined very precisely. Further, by the precise machining of the elastic support 12, the torsion spring constant can be determined very precisely. This means that the natural vibration mode frequency and center of gravity position of the vibration system can be determined very precisely. As a result, the process of partially removing the mass adjusting member 19 for adjusting the frequency or center of gravity position of the natural vibration mode can be performed at a higher speed. Further, when the area occupied by the mass adjusting member 19 is made small and when the mass adjusting member 19 is provided with a material of small density for more accurate frequency adjustment, the resolution for frequency adjustment is further improved. Can be.

Third Embodiment

An oscillator device according to a third embodiment of the present invention will be described below. FIG. 10A is a plan view of a vibrator device according to a third embodiment having two vibration members provided for vibration movement about the vibration axis 304. FIG. In this embodiment, these two vibrating members include first and second movable elements 302 and 320 having projections 303 and 321, respectively, for adjusting the mass of the vibrating member. The first movable element 302 is elastically supported by the first elastic support part (torsion spring) 305 to torsionally vibrate about the oscillation axis 304 relative to the second movable element 320. The second movable element 320 is elastically supported by the second elastic support (torsion spring) 306 so as to torsionally vibrate about the oscillation shaft 304 relative to the support member 301.

In this embodiment, no mass adjusting member is provided separately. Rather, portions of the movable elements 302 and 320 themselves are formed as protrusions 303 and 321 extending in a direction parallel to the oscillation axis 304 to serve as mass adjusting members. By cutting off a predetermined portion of each projection using a laser beam, an appropriate volume can be removed therefrom.

The vibrator device of this embodiment is not shown in accordance with the synthesized drive signal based on the reference frequency f ₀ (target drive frequency determined by the specification of the system application) and the frequency 2f _{0 which} is twice the reference frequency. Driven by the driving means. The vibrator device has two natural mode frequencies f ₁ and f ₂ about the oscillation axis 304, which approximately match the frequencies f ₀ and 2f ₀ , respectively, according to the method described in detail below. Is adjusted to be. Therefore, in the present embodiment, the composite wave driving based on two signals having frequencies f ₀ and 2f ₀ can be achieved while utilizing the high amplitude amplification factor of the natural vibration mode.

The synthesized wave driving method will be described in more detail below.

Fig. 11 is a graph in which the horizontal axis is the time t, which explains the angle of displacement of the first movable element 302 during the torsional vibration at the frequency f ₀ . Specifically, this figure shows a portion corresponding to the _{-T 0/2 <X <T} 0 / time of 2 days, one period of the torsional oscillation of the first movable element (302) (T _0).

Curve 61 shows a sinusoidal component of the reference frequency f ₀ of the torsional vibration of the first movable element 302. This is a sinusoidal vibration represented by the following expression reciprocating oscillation in the range of the maximum amplitude ± φ 1, time t, and each frequency w ₀ = 2πf ₀ .

[Equation 2]

θ ₁ = φ ₁ sin [w ₀ t]

On the other hand, the curve 62 shows a sinusoidal component of frequency twice the reference frequency f ₀ , which vibrates in the range of the maximum amplitude ± φ ₂ , and is a sinusoidal vibration represented by the following expression (3).

&Quot; (3) &quot;

θ ₂ = φ ₂ sin [2w ₀ t]

Curve 63 shows the angle of displacement of the torsional vibration of the first movable element 302 generated as a result of the drive described above. For torsional vibration about the oscillation axis 304, the vibrator device is subjected to the natural vibration mode of the frequency f ₁ which is respectively adjusted near the reference frequency f ₀ and the frequency 2f _{0 which} is twice the reference frequency as described above. And a second natural vibration mode of frequency f ₂ . Thus, both the resonance excited by the drive signal corresponding to θ ₁ and the resonance excited by the drive signal corresponding to θ ₂ occur in the vibrator device. In other words, the displacement angle of the first movable element 302 of the curve 63 is based on the vibration provided by the superposition of these two sinusoidal vibrations, i.e., sawtooth vibration occurs that can be expressed by Equation (4). do.

&Quot; (4) &quot;

θ = θ ₁ + θ ₂ = φ ₁ sin [w ₀ t] + φ ₂ sin [2w ₀ t]

FIG. 12 shows curves 61a and 63a and straight line 64a obtained by differentiating the curves 61 and 63 and the straight line 64 in FIG. 11, which show the angular velocity of these curves. Compared with the curve 61a showing the angular velocity of the sinusoidal vibration of the reference frequency f ₀ , the curve 63a showing the angular velocity of the reciprocating vibration of the sawtooth wave of the first movable element 302 is divided by N-N 'section. In, the angular velocity is maintained within a range having an upper limit and a lower limit corresponding to the angular velocity V ₁ of the maximum point and the angular velocity V ₂ of the minimum point, respectively. Therefore, in an oscillator device application where a reflecting surface is formed in the first movable element 302 to provide deflection scanning of light, if V ₁ and V ₂ permit the angular velocity from the straight line 64a corresponding to the isometric velocity scanning. If present within the margin of error, the N-N'section can be regarded as substantially an isometric velocity scanning region.

As described above, compared to the vibration based on the displacement angle along the sinusoidal wave, the sawtooth wave reciprocating vibration provides a very wide region where the angular velocity of the scan is substantially constant with respect to the angular velocity of the deflection scan. Thus, the ratio of usable area to total deflection scan area is significantly enlarged. Further, the modulation circuit is simplified because the modulation timing of the light source for light spot formation can be set without considering the nonuniformity of the angular velocity.

In addition, since the change in the angular velocity during vibration is small, the deformation of the reflective surface during driving is very small.

In addition, equally spaced scanning lines are ensured, which is very advantageous in applications such as printers, for example.

The foregoing description has been made with reference to an example in which the latter has a "double" relationship at the frequencies f ₁ and f ₂ of the natural vibration mode, which is approximately twice the former, while the latter is approximately three times the former. A triple " relationship can be established. In this case, similar to the "doubled" relationship, the vibration on the triangular wave is provided through the vibration based on the superposition of the sine waves. This allows the use of reciprocal scanning of light, so that the number of scan lines at a given available frequency can be doubled.

By the way, in such a vibrator device which is driven while simultaneously exciting the natural vibration modes in two or more torsional vibration directions, the smaller the mode attenuation ratio of each mode, the power consumption is reduced. On the other hand, if the mode attenuation ratio is small, the setting range for the target frequencies of the plurality of natural vibration modes (for example, the frequencies f ₁ and f ₂ in the optical deflector of the present embodiment) is narrowed. Therefore, when the power consumption of the optical deflector is lowered, the frequency of the natural vibration mode must be adjusted very precisely.

Referring to Fig. 13, a method of adjusting the frequencies f ₁ and f ₂ of the natural mode to the frequencies f ₀ and 2f ₀ will be described. FIG. 13 is a partially enlarged view showing the first movable element 302 and the protrusion 303 of the vibrator device shown in FIG. 10A. The central axis C through the protrusion 303 passes through the center of the thickness of the protrusion 303 (ie, the length in the normal direction to the ground of the drawing), which is parallel to the oscillation axis 304. The protrusion 303 has a uniform cross-sectional shape or cross-sectional area (along the cross section where the central axis C functions as a normal) regardless of the position. That is, for example at position A and position B, they have the same cross-sectional shape.

For removal of the protrusion 303, the volume to be removed is determined according to the difference (residual) of the frequency f ₁ (or frequency f ₂ ) from the reference frequency f ₀ (or 2f ₀ ). For removal, the projection 303 is cut along the cut cross section (ie along the cross section perpendicular to the center line C) in which the central axis C functions as a normal. Here, the removal amount is adjusted by adjusting the position of the cut portion. For example, the protrusion 303 is cut at position A or position B according to the above-described frequency difference (residue). The moment of inertia of the removed length La or Lb is equal to the product of the square of the square of the distance Dc between the central axis C and the oscillation axis 304 and the removal mass. The ratio of the moment of inertia adjustment at the positions A and B is equal to the ratio of the lengths La and Lb. Therefore, the removal amount is proportional to the length, and therefore the removal amount can be estimated quickly.

In addition, since the portion in the range from the cut portion to the tip of the protrusion is removed by the cutting operation, this portion is larger than the laser beam processing region, and the removal process can be completed very quickly. This not only shortens the machining time, but also is advantageous in that heat transfer to the vibrator device during laser beam machining is reduced. Therefore, unnecessary thermal damage or change in the physical properties of the vibrator device is well prevented. In addition, debris or dust particles from the projections generated by laser beam processing are reduced, and therefore contamination of the vibrator device is well prevented. In addition, since the laser and the processing length for achieving the required removal amount are uniform regardless of the position A or the position B, both the processing time and the processing movement amount (the processing laser scanning length or the processing stage movement amount) are constant. This makes oscillator device adjustment very simple and low cost.

The protrusions 303 and 321 of the first and second movable elements 302 and 320 are both configured parallel to the oscillation axis 304. Therefore, the cut sections for the protrusions 302 and 320 are parallel to each other. Therefore, laser beam processing can be performed in the same direction, and the structure of the laser beam processing apparatus can be simplified.

In the above-described manner, if a machining error occurs in the first and second elastic supports 305 and 306, etc., the two natural mode frequencies f ₁ and f ₂ are large with respect to the frequencies f ₀ and 2f ₀ . Even if there are differences, these frequencies can be adjusted accurately.

[Example 4]

The vibrator device according to the fourth embodiment of the present invention will now be described. Fig. 10B is a schematic top view showing a mass adjusting member 419 provided on a movable element that is oscillated about a vibration axis. The mass adjusting member 419 of the present embodiment has a plurality of protrusions 420 extending from the mass adjusting member 419 so as to be positioned above the void 430. In this embodiment, as shown by the broken line in Fig. 10B, for adjusting the frequency of the natural vibration mode to the target frequency about the vibration axis or for adjusting the center of gravity position of the vibration member to be aligned with the vibration axis, The base of the protrusion 420 is cut by the laser beam. More specifically, a suitable number of protrusions 420 are cut to a suitable removal volume. Once the position (distance from the vibration axis) and the mass of each projection are set, the amount of adjustment of the moment of inertia or center of gravity obtained by cutting the projection can be predicted. Therefore, the moment of inertia or the center of gravity can be controlled very precisely.

[Fifth Embodiment]

14, 15 and 16 show an optical deflector according to a fifth embodiment of the vibrator device of the present invention. 14 is a top view of a vibration system of the optical deflector, and FIG. 15 is a top view of a drive substrate having drive means for driving the vibration system. Fig. 16 is a sectional view taken along the line A-A in Fig. 14, which shows a structure in which the vibration system and the driving substrate are assembled. In this embodiment, as shown, the movable element 513 is formed with protrusions 503a, 503b, 503c and 503d, which provide a vibrating member. The vibration system includes this vibration member, a pair of elastic supports 512 and a support member 511. The movable element 513 has, for example, a dimension of 1.5 mm in the direction perpendicular to the vibration axis 517 and a dimension of 1 mm in the direction parallel thereto.

In the present embodiment, the movable element 513 is elastically supported by the pair of elastic support portions 512 for torsional vibration about the vibration axis 517. The protrusions 503a and 503b and the protrusions 503c and 503d are engaged with the movable element 513 in a symmetrical position with the oscillation axis interposed therebetween as shown. All of these protrusions extend in a direction parallel to the vibration axis 517. Further, comparing the pair of protrusions 503a and 503b (or the protrusions 503c and 503d) with each other, it can be seen that they have different lengths. That is, the protrusion engaging the movable element at the symmetrical position has an asymmetrical shape with respect to the oscillation axis 517.

15 shows a drive substrate 518 and a pair of drive electrodes 519. As shown, the drive electrode 519 is formed symmetrically with respect to the oscillation axis 517. Also, as shown in FIG. 16, the drive substrate 518 and the vibration system are assembled with spacers 520 interposed therebetween to maintain proper spacing therebetween. Therefore, the movable element 513 is disposed to face the drive electrode 519 with the gap therebetween. The movable element 513 is electrically grounded. Accordingly, by alternately applying a high voltage to the symmetrically arranged drive electrodes 519, an electrostatic attraction is generated between the movable element 513 and the voltage applied drive electrode 519. This generates torque about the vibration axis 517, which drives the vibration system.

The driving principle of the optical deflector of this embodiment is the same as that of the first embodiment. However, due to various error factors such as material property variations or processing tolerances, for example, the frequency f ₁ can be shifted from the reference frequency f ₀ . In the configuration shown in Fig. 14, a machining error defect 400 is caused by an error in mask shape during the dry etching process. Due to unintended factors in the semiconductor manufacturing process, such processing error defects may occur and thus the yield of the product may be lowered. The machining error defect 400 may be a defect having a shape such as a protrusion or recess shown in the present disclosure, or may be a stuck debris or the like.

The machining error defect 400 may be an error factor with respect to the moment of inertia of the entire vibration member. In this situation, as can be seen from Equation 1, an error may also occur at the frequency f ₁ of the natural vibration mode of the vibration system, so that a good amplitude amplification rate can no longer be obtained. In addition, the machining error defect 400 may offset the center of gravity of the entire vibration member from the design position in an unintended direction. When such an offset distance occurs, it generates unnecessary vibration which is very undesirable for the vibration of the vibration system. Since this may cause an inclination error of the reflecting surface of the movable element 513, the scanning characteristic may be deteriorated.

In the abnormal state in which there is no such center of gravity movement, the movable element 513 torsionally vibrates about the oscillation axis 517 in response to the drive signal of the frequency f ₀ . On the other hand, when the center of gravity movement occurs from the vibration shaft 517, the inertia force is generated in the movable element from the vibration shaft 517 toward the center of gravity position by the torsional vibration. This inertial force generates unwanted vibrations of characteristic frequencies in the offset direction of the center of gravity. As a result, the scanning characteristic is lowered.

The reduction in the aforementioned scanning characteristics can be prevented by adjusting both the frequency f ₁ of the natural vibration mode and the offset distance of the center of gravity, and a low power consumption optical deflector can be achieved.

Referring to Fig. 13 described in connection with the third embodiment, a method of simultaneously adjusting the frequency f ₁ of the natural vibration mode and the offset distance of the center of gravity is described. In FIG. 13, reference numeral 302 is understood as 513 corresponding to the movable element 513 in FIG. 14, and reference numeral 303 is understood as 503c corresponding to the protrusion 503c in FIG.

The central axis C extending beyond the protrusion 503c passes through the center of the thickness of the protrusion 503c (ie, the length in the normal direction to the ground) and is parallel to the vibration axis 517. The protrusion 503c has a uniform cross-sectional shape (along the cross section in which the central axis C functions as a normal) regardless of the position. That is, for example, at the position A and the position B, they have the same cross-sectional shape.

Regarding the removal of the projection 503c, the volume to be removed is determined according to the difference (remaining) of the frequency f ₁ from the reference frequency f ₀ and the offset distance of the center of gravity position. During removal, the projection 503c is cut along a cutting plane (ie, a cross section perpendicular to the centerline C) in which the central axis C functions as a normal. Here, the removal amount is adjusted by adjusting the cutting position.

For example, the projection 503c is cut at the position A or the position B by laser beam irradiation. The moment of inertia of the length La or Lb to be removed is equal to the product of the removal mass and the square of the distance Dc between the central axis C and the oscillation axis 517. Since the removal amount is proportional to the length, the ratio of the adjustment amount of the moment of inertia at the positions A and B provided by the mass removal is equal to the ratio of the lengths La and Lb.

On the other hand, as shown in Fig. 14, the protrusions are formed at positions symmetrical with respect to the vibration axis 517. Figure 14 shows the structure after the protrusions are partially removed according to the method described above. Prior to such mass removal, the paired protrusions 503a and 503b and the paired protrusions 503c and 503d may be formed to have the same width and length. Thus, with respect to paired protrusions 503a and 503b and paired protrusions 503c and 503d, the removal length is different. By adjusting this ratio, the offset distance of the center of gravity of the vibrating member can be adjusted.

In this embodiment, the frequency of the natural vibration mode of the vibration system is first measured, and the amount of adjustment of the moment of inertia for tuning it to the design value is estimated. The frequency measurement can be performed based on the information of the scanning beam detected using the light receiving element, the information detected by the piezoelectric resistor which can be installed on the elastic support, or the like. Based on the estimator, the sum of the lengths of the protrusions 503a to 503d to be removed is determined. In the manufacturing method of the vibrator device of the present embodiment having at least one natural vibration mode about the oscillation axis, this process includes the following steps. That is, measuring the frequency of the natural vibration mode around the vibration axis of the vibrator device, and determining the sum of the removal amount of the plurality of protrusions based on the measured frequency.

Then, according to the offset distance of the center of gravity position, the ratio of the removal length of the paired protrusions 503a and 503b or the paired protrusions 503c and 503d is determined. The offset distance of the center of gravity can be determined by measuring the scanning trajectory of the scanning light beam and estimating the difference (residue) from the ideal scanning trajectory. In the manufacturing method of the vibrator device of the present embodiment having at least one natural vibration mode about the oscillation axis, this process includes the following steps. That is, driving the vibrator device, detecting the vibration state or the driving waveform of the vibration member of the vibrator device, comparing the detected vibration state with the target vibration state, and reducing the offset distance based on the comparison result. Determining a ratio of the amount of removal of the protrusions.

The above-described determination of the sum of the removal amount and the ratio determination of the removal amount include the following steps: driving the vibrator device, detecting the vibration state of the vibration member of the vibrator device, and detecting the detected vibration state as the target vibration state. And determining the removal shape of the protrusion, based on the comparison result.

According to the removal length determined as described above, the laser beam irradiation position changes, and the protrusions 503a to 503d are machined to have an asymmetric length with respect to the oscillation axis 517. By this process, in this embodiment, adjustment of the frequency of the natural vibration mode and adjustment of the offset distance of the center of gravity can be performed simultaneously. In particular, in this embodiment, since the adjustment amount of the moment of inertia is proportional to the process length, the process target value can be immediately determined.

[Sixth Embodiment]

An oscillator device and a manufacturing method thereof according to a sixth embodiment of the present invention are described below. FIG. 17 is a plan view of an embodiment of an oscillator device including two vibration members provided to vibrate about an oscillation axis 604. In this embodiment, the two vibrating members include first and second movable elements 602, 620, respectively, having first and second protrusions 603, 621 for adjusting the mass of the vibrating member. The first movable element 602 is elastically supported to torsionally oscillate about the oscillation shaft 604 by the first elastic support (torsion spring) 605 with respect to the second movable element 620. The second movable element 620 is elastically supported by the second elastic support part (torsion spring) 606 with respect to the support member 601 to torsionally oscillate about the vibration axis 604. The permanent magnet 651 is fixed to the second movable element 620. The permanent magnet 651 is fixed to the opposing surface of the second movable element 620, one surface of which is shown in FIG.

In this embodiment, some of the first and second movable elements 602 and 620 themselves are formed with protrusions 603 and 621 extending in a direction parallel to the vibration axis 604. As in the fifth embodiment, these protrusions 603 and 621 are initially formed in a symmetrical shape at a symmetrical position with respect to the oscillation axis 604. Then, as in the fifth embodiment, the desired portion of the protrusions is cut by the laser beam, so that an appropriate volume of asymmetric length is removed from these protrusions.

The first movable element 602 and the first protrusion 603 constitute the first vibration member, and the second movable element 620, the second protrusion 621 and the permanent magnet 651 constitute the second vibration member. do. These vibration members can vibrate integrally about the vibration axis 604.

The vibrator device of this embodiment is a permanent magnet (2) according to a synthesized drive signal based on a reference frequency (a target drive frequency determined by the specification of the system application) f ₀ and a frequency 2f ₀ twice that reference frequency. It is driven by the drive means provided with the 651 and the fixed coil 652. 18 is a cross-sectional view taken along the line AA of FIG. 17. As shown in Fig. 18, the fixed coil generates a magnetic field in the direction of the arrow (H). This magnetic field acts on the permanent magnet 651 installed in the second movable element to generate torque about the oscillation shaft 304, thereby driving the vibration system.

The vibrator device has two natural mode frequencies f ₁ and f ₂ about the oscillation axis 604, which are adjusted to approximately match the frequencies f ₀ , 2f ₀ . Thus, in this embodiment, using the high amplitude amplification factor of the natural vibration mode, synthesized wave driving based on two signals having frequencies f ₀ and 2f ₀ is achieved. The synthesized wave driving method is the same as that of the third embodiment described with reference to Figs.

In this embodiment, the frequencies f ₁ and f ₂ of the two natural vibration modes of the vibration system about the vibration axis 604 have a "integer multiple" relationship. Accordingly, the moments of inertia of the first and second vibrating members must satisfy the following equation (5).

[Equation 5]

I ₂ / I ₁ ≥ 4n ² / (n ⁴ -2n ² +1)

Here, I ₁ and I ₂ are moments of inertia of each of the first and second vibration members, and n is an integer representing f ₂ / f ₁ .

The vibration system of this embodiment has a double relationship between the frequencies f ₁ and f ₂ , and therefore the relationship of the following equation (6) is satisfied.

&Quot; (6) &quot;

I ₂ / I ₁ ≥ 1.78

That is, in this embodiment, the second vibrating member has a greater moment of inertia than the first vibrating member. The magnitude relationship of the moment of inertia is effectively provided by providing a permanent magnet (drive means) 651 only in the second movable element 620. Thus, the permanent magnet 651 achieves a vibration member configuration suitable for realizing two natural vibration modes having twice the frequency relationship.

Here, as shown in Figs. 17 and 18, the case where the permanent magnet 651 is shifted to the left direction when seen in the drawing is bonded or installed. The center of gravity 668 of the permanent magnet 651 is offset from the vibration axis 604 to the left direction. On the other hand, with respect to the protrusion 621, the removal amount of one of the protrusions 621 located on the side where the permanent magnet 651 is moved, as shown in FIG. The ratio of the removal lengths of the asymmetric protrusions 621 asymmetric to the oscillation axis 604 can be determined by a method based on the scanning trajectory measurement described with reference to the fifth embodiment, for example.

Point 669 represents the center of gravity of the second movable element with a protrusion 621 that is partially removed by this asymmetric length described above. A line segment connecting the center of gravity 668 and the center of gravity 669 passes through the vibration axis 604. The ratio of the offset distance of the center of gravity of the permanent magnet 651 and the second movable element 620 from the vibration shaft 604 is almost equal to the ratio of the inverse of the mass of the permanent magnet 651 and the second movable element 620. Do. By this relationship, the center of gravity of the entire second vibrating member is disposed on the vibrating shaft 604.

Regarding the factors that can cause the offset of the center of gravity from the vibration axis 604, as described in the fifth embodiment, there may be other factors such as machining error. In any case, the offset distance of the center of gravity of the vibrating member can be adjusted by the method of the above-described embodiment.

Unnecessary vibration caused by the offset of the center of gravity of the vibrating member described above can cause the vibration system to couple between a plurality of natural vibration modes including a multiple degree of freedom vibration system, thereby greatly reducing scan reproducibility. Can be. In particular, in this embodiment, since the frequencies of the two natural vibration modes have a "double relationship", the above-mentioned frequency of unnecessary vibration may be twice the reference frequency. That is, it can be equal to the frequency of the other side. Thus, two natural vibration modes can be strongly coupled. As a result, in addition to the curvature of the scan trajectory, the scan reproducibility is very low.

In the present embodiment, the projections 603 and 621 are asymmetrically removed, so that not only the two frequencies f ₁ , f ₂ of the vibration system having two natural vibration modes but also the center of gravity of the two vibration members The offset distance can be adjusted at the same time. This can realize excellent scanning reproducibility as well as driving a synthesized wave at low power consumption. In this way, the moment of inertia and the center of gravity of the vibrating member can be adjusted quickly at the same time.

[Example 7]

19 is a schematic perspective view showing an embodiment of an optical apparatus equipped with an optical deflector according to the present invention. In this embodiment, the image forming apparatus is shown as an optical instrument. In Fig. 19, 3003 shows an optical deflector according to the present invention, which functions to scan incident light in one dimension. 3001 represents a laser light source, and 3002 represents a lens or lens group. 3004 is a writing lens or lens group, and 3005 is a drum type photosensitive member.

The laser beam emitted from the laser light source 3001 is modulated by a predetermined intensity modulation related to the timing of the deflection scan of the light. The intensity modulated light passes through the lens or lens group 3002 and is scan deflected one-dimensionally by an optical scanning system (optical deflector) 3003. The scanning deflected laser beam is focused on the photosensitive member 3005 by the write lens or lens group 3004 to form an image.

The photosensitive member 3005 rotates about a rotation axis in a direction perpendicular to the scanning direction, and is uniformly charged by a charger (not shown). By scanning light onto the photosensitive member surface, an electrostatic latent image is formed on the scanned surface portion. Thereafter, by using a developing device (not shown), the toner image is formed along the electrostatic latent image, and then the toner image is transferred and fixed to a transfer sheet (not shown), whereby an image is formed on the sheet.

According to this embodiment, it is possible to use an optical deflector well tuned to a desired frequency. Therefore, it is possible to drive at a high amplitude amplification rate, whereby the apparatus can be miniaturized and power consumption can be lowered. Further, the angular velocity of the deflection scan of the light can be made almost uniform in the effective area of the photosensitive member 3005 surface. In addition, by using the optical deflector of the present invention, an image forming apparatus capable of generating a clear image with less variation in scanning position is achieved.

Although the present invention has been described with reference to the structures disclosed herein, the present invention is not limited to the details and the present application encompasses changes or modifications for improvement purposes or within the scope of the following claims.

1A is a plan view of an optical deflector according to a first embodiment of the present invention.

Fig. 1B is a plan view of the side where the reflective surface of the vibration system of the first embodiment is not formed.

Fig. 2 is a sectional view showing the vibration member and the drive means of the first embodiment of the present invention.

Fig. 3 is a sectional view showing an alternative structure of the vibration member according to the first embodiment of the present invention.

4A is a plan view of an optical deflector according to a second embodiment of the present invention.

Fig. 4B is a plan view of the side where the reflecting surface of the vibration system of the second embodiment is not formed.

Fig. 5 is a sectional view for explaining the vibration member of the second embodiment of the present invention.

Fig. 6 is a sectional view for explaining the elastic support of the second embodiment of the present invention.

7A is a plan view for explaining one process of the laser beam machining process according to the present invention;

7B is a plan view for explaining another process of the laser beam machining process according to the present invention;

FIG. 7C is a sectional view for explaining a process corresponding to FIG. 7B. FIG.

8 is a schematic view illustrating a process for manufacturing a movable element having a recessed portion according to the second embodiment of the present invention.

9 is a schematic diagram illustrating a process for manufacturing a torsion spring according to a second embodiment of the present invention.

10A is a plan view of a vibration system according to a third embodiment of the present invention.

10B is a plan view of a mass adjusting member according to a fourth embodiment of the present invention.

Fig. 11 is a graph for explaining the displacement angle of the first movable element of the vibrator device according to the third embodiment of the present invention.

12 is a graph illustrating the angular velocity of the first movable element of the vibrator device according to the third embodiment of the present invention.

Fig. 13 is a partial plan view showing the first movable element and the projection of the third embodiment of the present invention.

14 is a plan view of a vibrator device according to a fifth embodiment of the present invention.

Fig. 15 is a plan view of a drive substrate of a vibrator device according to a fifth embodiment of the present invention.

Fig. 16 is a sectional view of an oscillator device according to a fifth embodiment of the present invention.

17 is a plan view of a vibrator device according to a sixth embodiment of the present invention.

Fig. 18 is a sectional view of an oscillator device according to a sixth embodiment of the present invention.

Fig. 19 is a perspective view of an optical apparatus equipped with an optical deflector according to the embodiment of the present invention.

20 is a perspective view of an optical deflector of known type.

<Explanation of symbols for the main parts of the drawings>

11, 302, 320: movable element

12, 305, 306: elastic support

13, 301: support member

17, 304: vibration axis

19, 419: mass adjusting member

22: reflecting surface

41: vibration member

85: mass removal part

151: permanent magnet

152: fixed coil

3001: laser light source

3003: Optical Deflector

3005: photosensitive member

Claims (22)

It has a vibration member, an elastic support part, and a support member, The said vibration member is a manufacturing method of the vibrator apparatus which is elastically supported by the said elastic support part, and vibrates about a vibration axis, Forming a vibrating member having a movable element having a projection for adjusting the mass of the vibrating member, the projections extending from the movable element in a direction parallel to the vibration axis and formed in pairs, Forming a vibrating member, wherein the pair is disposed at a position symmetrical with respect to the vibration axis, and the cross-sectional area of each protrusion along a plane orthogonal to the vibration axis is constant in the vibration axis direction; Projecting a laser beam at the cut position of the protrusion to partially remove the movable element, including a portion where the laser beam is not irradiated, from the cut position of the protrusion to the tip of the protrusion, And the projection is cut so that the total removal length of the projection is equal to a predetermined length, thereby adjusting the moment of inertia of the vibration member. The method of claim 1, wherein the total removal length of the protrusion is determined based on a difference between a frequency of a natural vibration mode around a vibration axis of the vibrator device and a target frequency. 3. A method according to claim 2, wherein the ratio of the amount of removal of the protrusion in a symmetrical position with respect to the vibration axis is determined to reduce the offset distance of the center of gravity of the vibration member from the vibration axis. The method of manufacturing a vibrator device according to claim 3, wherein each of the protrusions is formed only at a position farthest from the vibration shaft in the vibration member. The method of claim 4, wherein the vibrator device has a coil and a permanent magnet for driving the vibrating member, and the permanent magnet is provided to the vibrating member. And a first vibration member, a first elastic support, a second vibration member, a second elastic support, and a support member, wherein the first vibration member is elastically supported by the second vibration member through the first elastic support. A vibrator having a vibration about a vibration axis, wherein the second vibration member is elastically supported by the support member through the second elastic support and vibrates about the vibration axis, and has at least two natural vibration modes of different frequencies. Method of manufacturing the device, A first movable element having a protrusion configured to adjust a mass of the first vibrating member, wherein the protrusions extend in a direction parallel to the vibration axis from the first movable element, and are formed in pairs, respectively Pairs of are arranged at positions symmetrical with respect to the vibration axis, the cross-sectional area of each protrusion along a plane orthogonal to the vibration axis is constant in the direction of the vibration axis, forming the first vibration member, and And a second movable element having a protrusion for adjusting the mass, wherein the protrusions extend in a direction parallel to the vibration axis from the second movable element, and are formed in pairs, each pair with respect to the vibration axis. A stage for forming the second vibrating member disposed in a symmetrical position and having a cross-sectional area of each protrusion along a plane orthogonal to the vibrating axis is constant in the vibrating axis direction. And, At least one of the first movable element and the second movable element, including a portion in which the laser beam is not irradiated from the cut position of the protrusion to the tip of the protrusion to project the laser beam to the cut position of the protrusion. Partially removing the And the projection is cut so that the total removal length of the projection is equal to a predetermined length to adjust the moment of inertia of at least one of the first movable element and the second movable element. The method of claim 6, wherein the total removal length of the protrusion is determined based on a difference between a target frequency and a frequency of a natural vibration mode about the oscillation axis of the vibrator device. 8. A method according to claim 7, wherein the ratio of the amount of removal of the protrusion in a symmetrical position with respect to the vibration axis is determined to reduce the offset distance of the center of gravity of the vibration member from the vibration axis. The method of claim 8, wherein each of the protrusions is formed only at a position farthest from the vibration shaft in the vibration member. 10. The method of claim 9, wherein the vibrator device further includes a coil and a permanent magnet for driving the vibrating member, wherein the permanent magnet is provided to the vibrating member. 11. The method of claim 10, wherein the ratio of the amount of removal of the protrusions provided on the second vibration member and formed at a position symmetrical with respect to the vibration axis reduces the offset distance of the center of gravity of the second vibration member from the vibration axis. Method of manufacturing the vibrator device is determined to. delete delete delete delete delete delete delete delete delete delete delete

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