JP5400925B2 - Oscillator device, optical deflector, and optical apparatus using the same - 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

The present invention relates to an oscillator device having a movable element supported so as to be able to swing, an optical deflector using the same, an image forming apparatus using the same, an optical device such as a display, and a method of manufacturing the oscillator device. This optical deflector is preferably used in an image forming apparatus such as a projection display that projects an image by deflecting scanning of light, a laser beam printer having an electrophotographic process, a digital copying machine, or the like.

Conventionally, as an optical deflector, various optical scanning systems or optical scanning devices for deflecting light by sine-vibrating a movable element having a reflecting surface have been proposed. Here, an optical scanning system using an optical deflector that performs sinusoidal oscillation using a resonance phenomenon has the following characteristics compared to an optical scanning optical system using a rotating polygon mirror such as a polygon mirror. That is, the optical deflector can be greatly reduced in size, consumes less power, and in particular, the optical deflector made of single crystal silicon manufactured by the semiconductor manufacturing process has theoretically no metal fatigue and is durable. Is also excellent.

In the optical deflector using such a resonance phenomenon, a target natural vibration mode frequency is determined with respect to a desired driving frequency, and a method for producing this has been proposed.

In Japanese Patent Laid-Open No. 2002-40355 (Patent Document 1), as shown in FIG. 20, mass load portions 1001 and 1002 are provided at both ends of a movable plate having a reflecting surface and a coil elastically supported so as to be swingable on a torsion shaft. The formed planar galvanometer mirror is used. Then, by irradiating the mass load portions 1001 and 1002 of the galvano mirror with laser light, the mass is removed and the moment of inertia is adjusted to set the frequency to a desired value.

Japanese Patent Application Laid-Open No. 2004-219889 discloses a technique for applying a mass piece represented by a resin to a movable plate and adjusting the frequency based on the same principle as described above.

JP 2002-40355 A Japanese Patent Laid-Open No. 2004-219889

However, in the proposed examples of Patent Documents 1 and 2, if the adjustment range is large, the adjustment requires a long processing time. Also, according to these adjustment principles, it is difficult to adjust the frequency and the center of gravity quickly at the same time.

In view of the above problems, the method of manufacturing the oscillator device of the present invention has the following characteristics. That is, the oscillating portion of the oscillating device of the present invention is provided with an oscillating portion, an elastic support portion, and a support body, and the oscillating portion is supported by the elastic support portion so as to be oscillatable about the oscillating axis. And a mover and a mass adjuster for adjusting the mass of the swinging portion. A gap is formed between the movable element and a part of the mass adjusting body, and the gap including the portion that is not irradiated with the laser light by irradiating the mass adjusting body with laser light. It has the process of removing a part of said mass adjustment body above.

Moreover, in view of the said subject, the manufacturing method of the oscillator device of this invention has the following characteristics. That is, the oscillating portion of the oscillating device, which includes an oscillating portion, an elastic support portion, and a support body, the oscillating portion being supported by the elastic support portion so as to be oscillatable about the oscillating axis, It is comprised with the needle | mover with the protrusion part for adjusting the mass of a moving part. The protruding portion protrudes from the movable element in a direction parallel to the swing axis, and by irradiating the cutting portion of the protruding portion with laser light, the protruding portion ahead of the cutting portion that is not irradiated with the laser light. A part of the movable element including the part can be removed, and the removal amount is adjusted by changing the position of the cutting part.

Further, in view of the above problems, the manufacturing method of the oscillator device according to the present invention includes an oscillator, an elastic support, and a support, and the oscillator can swing around an oscillation axis by the elastic support. A method of manufacturing a supported oscillator device having the following characteristics. That is, the oscillating part is composed of a mover having a plurality of projecting parts for adjusting the mass of the oscillating part, and the projecting parts are arranged on opposite sides of the oscillating shaft. Then, by cutting the cutting part of the protruding part, it is possible to remove a part of the movable element including the protruding part from the cutting part, and by changing the position of the cutting part, the inertia of the swinging part A step of adjusting the moment and the offset distance of the center of gravity of the swinging portion from the swinging shaft is provided.

In view of the above problems, the oscillator device of the present invention includes an oscillating portion, an elastic support portion, and a support body, and the oscillating portion is supported by the elastic support portion so as to be swingable about the oscillating axis. The oscillator device has the following characteristics. That is, the oscillating part is composed of a movable element in which a mass adjusting body for adjusting the mass of the oscillating part is arranged, and a gap is formed between the movable element and a part of the mass adjusting body. It is characterized by being.

In view of the above problems, the oscillator device of the present invention includes an oscillating portion, an elastic support portion, and a support body, and the oscillating portion is supported by the elastic support portion so as to be swingable about the oscillating axis. The oscillator device has the following characteristics. That is, the oscillating part is composed of a mover having a protruding part for adjusting the mass of the oscillating part, and the protruding part protrudes from the mover in a direction parallel to the oscillating shaft. And the cross-sectional area of the projecting portion having the swing axis as a normal line is constant in the swing axis direction.

In view of the above problems, the oscillator device of the present invention is an oscillator device including a vibration system and a driving means for driving the vibration system, and has the following characteristics. That is, the vibration system includes a first swing part, a first elastic support part, a second swing part, a second elastic support part, and a support. The first oscillating portion includes a first mover having a protruding portion for adjusting the mass of the first oscillating portion, and the second oscillating portion adjusts the mass of the second oscillating portion. It consists of a second mover with a protruding part for. Further, the protruding portion protrudes from the movable element in a direction parallel to the swing axis, and a cross-sectional area of the protruding portion with the swing axis as a normal line is constant in the swing axis direction. The first mover is elastically supported by the second mover so as to be swingable about the swing axis by the first elastic support portion, and the second mover is rocked by the second elastic support portion by the second elastic support portion. It is elastically supported so that it can swing around the moving axis. The vibration system has at least two natural vibration modes having different frequencies around the swing axis.

In view of the above problems, the oscillator device of the present invention includes an oscillating portion, an elastic support portion, and a support body, and the oscillating portion is supported by the elastic support portion so as to be swingable about the oscillating axis. The oscillator device has the following characteristics. That is, the oscillating part is composed of a mover having a plurality of projecting parts for adjusting the mass of the oscillating part, and the projecting parts form a pair at positions symmetrical to the oscillating axis. Arranged. The protruding portions at the symmetrical positions have different shapes, and the center of gravity of the swinging portion is on the swinging shaft.

Further, in view of the above problems, the oscillator device of the present invention includes a vibration system and drive means for driving the vibration system, and has the following characteristics. In other words, the vibration system includes a first swing part, a first elastic support part, a second swing part, a second elastic support part, and a support. The first oscillating portion includes a first mover having a plurality of first protrusions for adjusting the mass of the first oscillating portion, and the second oscillating portion includes the second oscillating portion. A second movable element having a plurality of second projecting portions for adjusting the mass of the portion. The plurality of first projecting portions and the second projecting portions are respectively disposed at symmetrical positions with respect to the swing axis, and the projecting portions at least one of the first projecting portion and the second projecting portion are symmetrical to each other. The shape is different. The centers of gravity of the first and second rocking portions are on the rocking shaft. The first mover is elastically supported by the second mover so as to be swingable about a swing axis by a first elastic support portion, and the second mover is supported by the second elastic support portion on the support body. And is elastically supported so as to be swingable around the swing axis. The vibration system has at least two natural vibration modes having different frequencies around the swing axis.

Further, in view of the above problems, an image forming apparatus that is one of the optical apparatuses of the present invention has the following characteristics. That is, it has a light source, an optical deflector, and a photosensitive member, and the optical deflector deflects light from the light source and causes at least a part of the light to enter the photosensitive member. In view of the above problems, an image display device which is one of the optical devices of the present invention has the following characteristics. That is, it has a light source, an optical deflector, and an image display body, and the optical deflector deflects light from the light source and causes at least a part of the light to enter the image display body.

In an oscillator device such as an optical deflector that performs optical scanning or an adjustment method thereof according to the present invention, the oscillator includes a mover and a mass adjuster, and a gap is formed between the mover and the mass adjuster. Therefore, a relatively large mass can be removed at a relatively high speed.

Moreover, since the protrusion for mass adjustment is formed on the mover, a relatively large mass can be removed at a relatively high speed. Therefore, it is possible to adjust the moment of inertia of the swinging portion or the position of the center of gravity at a relatively high speed within a relatively large range.

(A) is a top view showing the optical deflector of the first embodiment of the present invention, and (b) is a top view on the side where the reflection surface of the vibration system of the first embodiment of the present invention is not formed. . FIG. 2 is a cross-sectional view showing a swinging portion and driving means of a first embodiment of the present invention. FIG. 6 is a cross-sectional view showing a modification of the swinging portion in the first embodiment of the present invention. (A) is a top view showing an optical deflector according to a second embodiment of the present invention, and (b) is a top view on the side where a reflecting surface of a vibration system according to the second embodiment of the present invention is not formed. . FIG. 6 is a cross-sectional view showing a rocking part of a second embodiment of the present invention. FIG. 6 is a cross-sectional view showing an elastic support portion of a second embodiment of the present invention. (A) is a top view explaining one process of the laser processing of the embodiment of the present invention, (b) is a top view explaining another process of the laser processing of the embodiment of the present invention, (c) These are sectional drawings explaining the process corresponding to (b) of the laser processing of the Example of this invention. FIG. 6 is a cross-sectional view showing a manufacturing process of a mover having a recess according to a second embodiment of the present invention. FIG. 6 is a cross-sectional view showing a process for manufacturing a torsion spring according to a second embodiment of the present invention. (A) is a top view which shows the vibration system of the 3rd Example of this invention, (b) is a top view of the mass adjustment body of the 4th Example of this invention. FIG. 10 is a diagram showing a displacement angle of a first mover of an oscillator device according to a third exemplary embodiment of the present invention. FIG. 10 is a diagram showing an angular velocity of a first mover of an oscillator device according to a third example of the present invention. FIG. 10 is a top view showing a first mover and a protrusion of a third embodiment of the present invention. FIG. 10 is a top view showing an oscillator device according to a fifth embodiment of the present invention. FIG. 10 is a top view showing a drive substrate of an oscillator device according to a fifth embodiment of the present invention. FIG. 10 is a cross-sectional view of an oscillator device according to a fifth embodiment of the present invention. FIG. 10 is a top view showing an oscillator device according to a sixth embodiment of the present invention. FIG. 10 is a cross-sectional view showing an oscillator device according to a sixth embodiment of the present invention. It is a perspective view which shows the Example of the optical instrument using the optical deflector of this invention. It is a perspective view which shows the optical deflector of a prior art example.

Hereinafter, an embodiment of the present invention will be described. The oscillator device of the present embodiment has at least one oscillating portion provided so as to be able to oscillate around the oscillating shaft. And the rocking | swiveling part is comprised with the needle | mover by which the mass adjustment body for adjusting the mass is arrange | positioned, and has a space | gap between a needle | mover and a mass adjustment body. This gap allows a part of the mass adjusting body to be separated from the mover. A space | gap is a recessed part provided in the needle | mover or the mass adjustment body. The oscillator device may include a vibration system and a driving unit for driving the vibration system. In this case, the vibration system is composed of the swinging portion, the support body, and the elastic support portion, and the mover is elastically supported with respect to the support body so as to be swingable around the swing shaft by the elastic support portion. Is done. A reflecting surface which is an optical deflecting element may be installed on the movable element so as to be configured as an optical deflector. In the method of manufacturing the oscillator device, at least one of adjustment of the frequency of at least one natural vibration mode around the oscillation axis to the target frequency and adjustment / coincidence of the position of the center of gravity of the oscillation unit to the oscillation axis is performed. In order to do this, For example, there is a method of excising a part of the mass adjusting body in the gap with a laser beam. The form of the part of the mass adjusting body on the gap may be a form in which the part of the mass adjusting body extends entirely on the gap, or a part of the mass adjusting body extends as a protruding portion by protruding onto the gap. It may be a form. In the latter case, if the position of the protrusion (distance from the swing axis) and the mass are set, when the protrusion is excised (for example, cutting the root of the protrusion with a laser beam), It will be understood in advance how much the moment of inertia and the position of the center of gravity can be adjusted. If a plurality of such gaps and protrusions are provided, the moment of inertia and the position of the center of gravity can be adjusted very quickly and accurately.

Particularly in this case, since the mass adjuster is provided on the mover, the area of the mover is not increased. Therefore, the mass adjuster can be provided without increasing the air resistance when the mover swings around the swing axis.

In another example of the method of manufacturing the oscillator device according to the present embodiment, the separated portion of the mass adjuster is irradiated with a laser beam scanned in a closed curve (for example, in a circumferential shape), Remove the mass adjuster to create the swinging part. The portion of the mass adjuster surrounded by the closed curve (where no laser light is irradiated) is also removed because it is separated from the mover by the gap. Therefore, the moment of inertia around the swing axis that the removal portion has is subtracted from the moment of inertia around the swing axis of the swing portion. Alternatively, the position of the center of gravity is adjusted due to a decrease in the mass of the removed portion.

In this way, the frequency of the natural vibration mode and the position of the center of gravity of the vibration system can be changed. That is, by appropriately selecting the volume and position of the removed portion to be removed from the mass adjuster, the inertia moment and the gravity center position can be adjusted to the desired inertia moment and gravity center position. In particular, by selecting the density of the mass adjuster appropriately (for example, by reducing the specific gravity of the mass adjuster), the frequency adjustment resolution can be selected regardless of the removal volume resolution or positioning resolution. It becomes possible. Further, if the mass of the closed curve is removed by irradiating the laser beam, the mass adjusting body part surrounded by the closed curve can also be removed due to the presence of the gap, so that a large mass can be removed at high speed. Therefore, the inertia moment and the position of the center of gravity can be adjusted at a relatively high speed with a relatively large adjustment range. Furthermore, the presence of the air gap makes it possible to accurately remove only the mass adjuster without removing a part of the mover during laser processing, and thus the above adjustment can be performed with high accuracy. In other words, if there is no gap, it is possible to remove even a part of the mover directly below the mass adjuster during laser processing, but if a gap is provided, such a situation can be reliably avoided.

The following form can also be adopted as an oscillating device including an oscillating part provided to be oscillatable around the oscillating shaft. In this embodiment, the oscillating portion is constituted by a mover having a protruding portion for adjusting the mass of the oscillating portion. In other words, here, the mass adjuster is not provided separately, but a part of the mover itself serves as a part that plays the role of the mass adjuster. As the form of the protrusion, there are a protrusion extending in a direction parallel to the swing axis and a protrusion extending in a direction perpendicular to the swing axis. In addition, there is a method in which the movable element is formed into a trapezoidal shape or a pincushion shape, for example, and an acute corner is used as the protruding portion.

In particular, with respect to the protruding portion extending in the direction parallel to the swing axis, the removal amount from the cutting portion to the tip of the protruding portion is adjusted by adjusting the position of the cutting portion that irradiates the laser beam.

Furthermore, according to this embodiment, the size of the processing region for laser processing is constant and small regardless of the amount of removal. Therefore, not only can the moment of inertia be adjusted quickly, but also the transfer of heat to the oscillator device associated with laser processing can be suppressed even if the removal amount increases.

Further, since the resolution of the removal amount can be finely adjusted by finely adjusting the position of the cutting portion, a large adjustment width and an accurate resolution can be realized. Furthermore, if the cross-sectional shape perpendicular to the swing axis is a constant protrusion in the swing axis direction, the length from the cutting part to the tip of the protrusion and the inertia moment adjustment amount of the swing part around the swing axis However, since the relationship is almost proportional, the moment of inertia can be easily adjusted.

Further, since all the protrusions extend in parallel with the swing axis, the instability of the swing displacement angle and phase can be reduced compared to the case where the protrusion extends in the direction perpendicular to the swing axis. This is because this instability is caused by fluctuations in resistance received by the oscillating unit from ambient air. In particular, in an oscillator device formed with a minute size on the order of several millimeters, there is a portion where the distance from the oscillation axis of the oscillation is far (the displacement speed is high) in the fluctuation of the air resistance, which is a big problem. It becomes more noticeable. By forming all the protrusions parallel to the swing axis, scanning stability and quick adjustment of the moment of inertia can be achieved simultaneously. This is most effectively achieved when the protrusion is formed only at the position farthest from the swing axis of the swing section.

If microfabrication is applied by applying semiconductor manufacturing technology, the movable part and the protruding part of the oscillating part can be formed monolithically, so that the oscillating part having the inertia moment adjustment mechanism can be formed with high accuracy. It becomes.

The oscillating body device can also be constituted by a vibration system including two oscillating portions provided so as to be able to oscillate around the oscillating shaft and a driving means for driving the oscillation system. In this embodiment, the first oscillating portion is constituted by a first mover having a protruding portion extending in a direction parallel to the oscillating axis. Similarly, the second oscillating part is composed of a second mover having a protruding part extending in a direction parallel to the oscillating axis. The cross-sectional area with the swing axis of the protrusions formed on the first and second swing parts as a normal is constant in the swing axis direction. The vibration system has two natural vibration modes around the swing axis. In this case, the removal amount can be adjusted by adjusting the positions of the cutting portions that irradiate the projecting portion of the first movable element and the projecting portion of the second movable element with the laser beam.

In addition, by providing protrusions parallel to the swing axis common to the vibration system on the first swing portion and the second swing portion, the cutting direction is common to the first and second movers. The cutting device is simplified.

Further, in the method of manufacturing the oscillator device, in order to simultaneously adjust the frequency of at least one natural vibration mode around the oscillation axis to the target frequency and adjust the position of the center of gravity of the oscillation unit, the following is performed. You can also A part of the protruding portion protruding from the mover is cut. For example, excision with a laser beam. By adjusting the position of the cutting portion that irradiates the laser light, the removal amount from the cutting portion to the tip of the protruding portion is adjusted. The plurality of protrusions are initially formed in a symmetrical shape at positions symmetrical with respect to the swing axis. Usually, after adjustment, the protruding portions forming a pair have different amounts of removal, and the final processed shapes are different.

By removing at least a part of the protruding portion, the moment of inertia of the swinging portion is adjusted according to the removal amount. The offset distance of the center of gravity of the oscillating portion from the oscillating shaft is also adjusted at the same time due to the asymmetry of the removal amount of the pair of protruding portions. Also here, the same effect as the embodiment of removing the protruding portion described above can be obtained. Furthermore, since the respective adjustments of the moment of inertia and the offset distance of the center of gravity can be performed simultaneously using the same protruding portion, the processing becomes quick. In addition, the number of protrusions provided for adjustment can be reduced, and both the moment of inertia and mass of the swinging part can be reduced. As a result, the entire oscillator device can be reduced in size, and the air resistance received when the oscillator swings can be reduced, and the stability of the swing motion of the oscillator can be improved.

Moreover, the following form can also be employ | adopted as an oscillating body apparatus containing the rocking | swiveling part provided so that rocking | fluctuation around the rocking | fluctuation axis | shaft was possible. All the protrusions of the oscillator device extend parallel to the oscillation axis, and the cross-sectional area with the oscillation axis as a normal line is constant in the oscillation axis direction and is symmetric with respect to the oscillation axis. The protrusions may be processed with different lengths.

According to this aspect, the sum of the removal lengths is related to the adjustment amount of the moment of inertia, and the ratio of the removal lengths of the plurality of protrusions is the adjustment amount of the offset distance from the swing axis of the center of gravity of the swinging portion. Is related to. Therefore, if the total amount is determined from the adjustment amount of the moment of inertia and the ratio of the removal length is determined from the adjustment amount of the offset distance, the inertia moment and the offset distance of the center of gravity are adjusted at the same time. The Here, the adjustment amount of the moment of inertia and the total amount of the removal length are in a proportional relationship. Therefore, the adjustment amount of the moment of inertia and the adjustment amount of the offset distance of the center of gravity can be determined easily and accurately.

Here too, the effect of the protrusions extending in parallel with the swing axis is achieved. Also here, if the microfabrication is performed by applying the semiconductor manufacturing technique, the movable part of the swinging part and the plurality of protruding parts can be formed monolithically. Therefore, it is possible to create a structure capable of adjusting the moment of inertia and the offset distance of the center of gravity with high accuracy.

Moreover, the following form can also be employ | adopted as an oscillating body apparatus containing the rocking | swiveling part provided so that rocking | fluctuation around the rocking | fluctuation axis | shaft was possible. That is, the oscillator device can also install a permanent magnet as a driving means on the mover, and drive the mover having a magnet with an electromagnetic force from a coil installed outside the vibration system. In this embodiment, the permanent magnet is installed on the mover, and the center of gravity of the permanent magnet is offset from the swing axis. For example, the center of gravity is offset due to random displacement of the permanent magnet installation position due to processing errors. However, as in the above embodiment, the center of gravity of the mover can be offset from the swing axis by removing at least a part of the protrusion formed on the mover. The offset of the center of gravity of the child can be canceled out. That is, if at least a part of the protrusion is removed as follows, the two are offset. The ratio of the distance from the intersection where the line connecting the center of gravity of the permanent magnet and the center of gravity of the mover intersects the axis of oscillation to the center of gravity of each is almost the same as the ratio of the reciprocal of the mass of each permanent magnet and mover Remove the protrusion. Thereby, the center of gravity of the entire swinging portion is on the swinging shaft.

In this way, in a small oscillator device including a driving means using electromagnetic force that can largely drive the oscillator, it is possible to simultaneously adjust the frequency and the offset distance of the center of gravity. Permanent magnets deteriorate in magnetic properties due to heating. Therefore, even if the removal amount increases, the configuration of the above embodiment in which the processing area does not increase can suppress the heat transfer accompanying laser processing, and can create a mover having a permanent magnet having good magnetic characteristics.

In addition, an oscillator device including two oscillators provided so as to be able to swing around the swing axis and a driving means for driving the oscillator system constitute an oscillator device different from the above-mentioned type. You can also. In this embodiment, the first swing part is constituted by a first mover having a plurality of protrusions extending in a direction parallel to the swing axis. Similarly, the second oscillating portion is composed of a second mover having a plurality of projecting portions extending in a direction parallel to the oscillating shaft. The vibration system has two natural vibration modes around the swing axis. Here, the removal amount of each protrusion can be adjusted by adjusting the position of the cutting portion that irradiates the laser light of the protrusion of the first mover and the protrusion of the second mover. Also, by providing protrusions parallel to the swing axis common to the vibration system on the first swing portion and the second swing portion, the cutting direction is made common to the first mover and the second mover. The cutting device is simplified.

By the way, even in the above-described form in which the swinging unit is configured by a mover in which a mass adjusting body for adjusting the mass is arranged and has a gap between the mover and the mass adjusting body, In this way, it is possible to simultaneously adjust the frequency and the offset distance of the center of gravity. Mass adjusters are arranged on both sides of the mover across the swing shaft, and the amount of removal of the mass adjusters on both sides and the distance from the swing shaft are the amount of inertia moment adjustment and the center of gravity offset distance adjustment. On the basis of the above. Then, by removing a part of the mass adjuster according to this determination, it is possible to easily and accurately adjust the frequency and the offset distance of the center of gravity.

When an optical deflector is provided by installing a reflecting surface for deflecting light on the mover, an optical deflector that is well adjusted to a desired frequency or center-of-gravity offset amount is used when performing image formation or image display. it can. When the frequency of the natural vibration mode is adjusted, the optical deflector can be driven with a high amplitude amplification factor, and thus can be reduced in size and power consumption. In addition, when the offset amount of the center of gravity from the swing shaft is well adjusted, the swing shaft of the swing section does not move with scanning, and the scanning line is bent or reproducibility is lost. Deterioration is difficult to occur.

An image forming apparatus using the optical deflector includes a light source, the optical deflector, and a photosensitive member. The optical deflector deflects light from the light source and makes at least a part of the light incident on the photosensitive member. Let Further, an image display device using the optical deflector includes a light source, the optical deflector, and an image display body. The optical deflector deflects light from the light source, and at least part of the light. Incident on the image display.

In particular, when an optical deflector is provided by installing a reflecting surface for deflecting light on one of the movable elements of the vibration system including the two rocking parts, when performing image formation or image display, It is possible to use an optical deflector in which two natural vibration modes are well adjusted to a frequency relationship of 2 or 3 times. This optical deflector can be driven not only with a high amplitude amplification factor, but also by performing synthetic wave driving of the frequency-related sine wave to improve the uniformity of the angular velocity of optical scanning. Therefore, it is possible to reduce the deformation of the reflecting surface due to the change in angular acceleration due to the swing. Further, when forming a spot, the modulation circuit can be simplified because it is not necessary to take into account the non-uniformity of the angular velocity in the modulation timing of the light source. Furthermore, when the offset amount of the center of gravity is well adjusted, it is possible to suppress undesirable fluctuations in vibration caused by coupling that inhibits the independence of the two natural vibration modes of the vibration system. Can do. Such fluctuations in vibration can be reduced by reducing the offset amount of the center of gravity and adjusting the frequency of the two natural vibration modes to an integer multiple relationship. Such fluctuations in vibration also cause fluctuations in the angular velocity around the swinging axis of the swinging part and cause instability of optical scanning, so it is preferable to suppress the fluctuations.

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

(First embodiment)
1 and 2 are views showing a first embodiment of an optical deflector which is an example of an oscillator device of the present invention. 1A is a top view of the optical deflector, FIG. 1B is a top view of the vibration system viewed from the back side of FIG. 1A, and FIG. 2 is a line AA in FIG. FIG. In the present embodiment, the mass adjuster 19, the reflecting surface 22, and the gap 30 are installed on the mover 11 as shown in the figure, and constitute a swing part 41. Here, the vibration system includes a swinging portion 41, an elastic support portion 12, and a support body 13.

First, the driving principle of the present embodiment, together with the configuration, will be described with reference to the drawings. In the present embodiment, the vibration system shown in FIG. 1 is torsionally oscillated around the rocking shaft 17 by driving means described later. 1 are integrally formed from a single crystal silicon substrate by photolithography and dry etching of a semiconductor manufacturing method. Therefore, a small vibration system can be formed at a relatively low cost. In addition, since single crystal silicon has a high Young's modulus and a low density, it is possible to form a vibration system in which the deformation of the mover due to its own weight is small and the amplitude amplification factor at resonance is high. For example, the mover 11 has a size of 3 mm in a direction perpendicular to the swing shaft 17 and a size of 1 mm in a parallel direction, and the total length of the vibration system is about 12 mm.

The two movers 11 are elastically supported by a pair of elastic support portions 12 so as to be capable of torsional vibration at the center of the swing shaft 17. Further, the pair of mass adjusters 19 and the pair of gaps 30 are respectively installed on opposite sides of the swing shaft 17.

The reflection surface 22 installed on the movable element 11 deflects and scans light from the light source by torsional vibration of the movable element 11. Here, the material of the reflecting surface 22 is aluminum, which is formed by vacuum deposition. The reflective surface may be made of another material, such as gold or copper, and a protective film may be formed on the outermost surface. Since the movable element 11 has a reflecting surface 22, flatness during driving is particularly important. However, by supporting two ends with a pair of elastic support portions (torsion springs) 12, Compared to the case, the deformation due to its own weight can be suppressed and the flatness can be kept good.

FIG. 2 shows the fixed body 150 and the driving means. As shown in the figure, the driving means of the present embodiment includes a fixed coil 152 fixed to the fixed body 150 and a permanent magnet 151 installed on the back surface of the mover 11 of the swing part 41. As shown in FIGS. 1B and 2, the permanent magnet 151 included in the swing part 41 is, for example, a prismatic metal magnet having a length of about 2 mm and a cross section of 150 μm × 150 μm. The permanent magnet 151 has a longitudinal magnetization direction and is fixed to the movable element 11 with an adhesive.

As shown in FIG. 2, the fixed body 150 appropriately holds the positions of the vibration system / permanent magnet 151 and the fixed coil 152. The fixed coil 152 generates an AC magnetic field in the direction of the arrow H shown in FIG. Since the direction of the magnetic flux density of the permanent magnet 151 is an arrow B, the torque around the swing shaft 17 is generated by the magnetic field generated by the fixed coil 152, and the vibration system can be driven.

Next, the driving principle of the optical deflector of this embodiment will be described in more detail. The vibration system of the present embodiment has a natural vibration mode of frequency f ₁ with respect to torsional vibration about the rocking shaft 17. In this natural vibration mode, the inertial moment of the swinging part 41 around the swinging shaft 17 is I, and the spring constant of the two elastic support parts 12 around the swinging shaft 17 is K. It is calculated from the relationship of Equation 1 indicating the frequency of the vibration mode.
f ₁ = 1 / 2π · √ (K / I) (Formula 1)

Equation 1 is a sufficient approximation when the damping term (eg, air resistance) of the vibration system is small. The vibration system of the present embodiment has a damping ratio of about 0.003. Then, the fixed coil 152 drives the vibration system by the reference frequency f ₀ which is the target drive frequency determined from the application specification of the present invention. When the reference frequency f ₀ and the frequency f ₁ coincide with each other, the driving is performed at a point where the amplitude amplification factor of the natural vibration mode is the highest.

However, the frequency f ₁ may deviate from the reference frequency f ₀ due to various error factors such as material property variations and processing tolerances. Therefore, by removing a part of the mass adjusting body 19, the inertia moment I of the oscillating portion 41 in the equation 1 is adjusted, and the frequency f ₁ is adjusted to the reference frequency f ₀ . The mass adjusting body 19 of this embodiment is formed by adhering an aluminum flat plate to the mover 11 as shown in FIGS.

As described above, the adjustment amount of the moment of inertia can be increased or decreased depending on the volume of the removed portion of the mass adjuster 19 and the distance from the swing shaft 17. For example, assuming the error range of the frequency f _1, as the frequency f _1, including the error range is lower than the reference frequency f _0, by setting the inertia moment I and the spring constant K, the reference frequency frequency f ₁ Adjustment to f ₀ is possible. For example, prior to partly removing the mass adjusting member 19, by measuring the frequency f ₁ by measuring the vibration amplitude of the movable element 11 while sweeping the driving frequency, it is possible to know the amount of removal required. Here, if the density of the mass adjuster 19 is appropriately set, the adjustment resolution of the frequency f ₁ can be set regardless of the resolution of the volume of the portion to be removed and the distance from the swing shaft 17.

Further, in the present embodiment, the mass adjuster 19 is installed on the surface opposite to the surface on which the permanent magnet 151 of the plate-like movable element 11 is installed. Accordingly, it is possible to reduce the deviation of the center of gravity of the swing part 41 from the swing shaft 17 and reduce unnecessary vibration. Further, by removing a part of the mass adjusting body 19, it is possible to reduce the deviation of the center of gravity of the swinging portion 41 from the swinging shaft 17. For example, the observation laser beam is incident on the reflecting surface 22 and the scanning locus is observed, whereby the torsional vibration locus around the oscillation shaft 17 is observed. Then, by removing the mass adjuster 19 so that unnecessary vibration is reduced, the center-of-gravity shift can be reduced.

Next, the process of removing a part of the mass adjuster 19 will be described in detail with reference to the drawings. As shown in FIG. 1B, the mover 11 of this embodiment has a gap 30 formed by a through hole. Therefore, as shown in FIG. 2, a part of the mass adjuster 19 is not bonded to the movable element 11. The air gap 30 is formed simultaneously when the vibration system is formed from the single crystal silicon substrate by dry etching.

FIG. 7 is a conceptual diagram illustrating a process of removing the mass adjusting body 19 of the present embodiment. In the mass adjusting body 19 of the present embodiment, a part of the mass is removed by irradiating the processed portion with a pulse laser. FIG. 7A is a top view of a processing portion at the initial stage of laser processing, FIG. 7B is a top view showing a state where the processing has further progressed from the laser processing step (a), and FIG. It is sectional drawing cut | disconnected by CC line of 7 (b).

As shown in FIG. 7C, in the mass adjusting body 19 of the present embodiment, the mass removing portion 85 which is a part of the portion not bonded to the movable element 11 by the gap 30 is finally removed.

First, as shown in FIG. 7A, the machining laser spot 80 is scanned along a machining locus 82 in a closed curve shape that draws an arc as in the rotation direction 83. The processing laser spot 80 emits light with an output and a pulse frequency suitable for processing the mass adjuster 19. As shown in the drawing, a machining portion 81 along the machining locus 82 is formed by the machining laser spot 80.

FIG. 7B shows a state after the machining laser spot 80 has circulated an appropriate number of times along the machining locus 82. As shown in the figure, a penetrating portion 84 is formed along the machining locus 82. FIG. 7C shows a cross section of this portion. The machining laser spot 80 further circulates around the machining locus 82 and removes the periphery of the mass removal portion 85 in an arcuate closed curve. As shown in FIG. 7C, the mass removal portion 85 is not bonded to the mover 11 due to the presence of the gap 30, and is thus separated from the mover 11 by the above-described process.

If the diameter of the machining locus 82 is increased in the above process, a large mass can be removed at high speed. Of course, the shape of the machining locus 82 is not limited to the above-mentioned arcuate closed curve.

As described above, in this embodiment, due to the effect of the air gap 30, a volume larger than the volume that is actually removed by being irradiated with laser light can be removed at high speed. Therefore, the frequency adjustment range and the gravity center position adjustment range of the natural vibration mode can be increased, and further adjustment can be performed at high speed. In addition, because of the presence of the air gap 30, only the mass adjuster 19 can be removed without removing part of the mover 11 during laser processing, so the natural vibration mode frequency adjustment and center of gravity adjustment of the vibration system are highly accurate. Can be performed.

Furthermore, since the mass adjuster 19 can be formed as a flat plate by providing the gap 30 as a through hole in the movable element 11 as in the present embodiment, assembly for bonding is facilitated. As a material of the mass adjusting body 19 of the present embodiment, a metal, a dielectric, a semiconductor or the like that absorbs a processing laser beam can be used.

Incidentally, the movable element 11 and the mass adjusting body 19 of the present embodiment may be configured as shown in FIG. FIG. 3 is a sectional view taken along line AA in FIG. Unlike the case of FIG. 2 described above, in the configuration shown in FIG. 3, a gap 30 is provided in the mass adjuster 19. Even in this case, a similar effect can be obtained with respect to mass removal by laser light irradiation.

In the above embodiment of the oscillator device of the present invention, the optical deflector that reflects and deflects light has been described. However, for example, it can be used for a sensor or the like that detects mass adhesion by measuring a change in vibration frequency due to mass adhering to the mover 11 from the outside.

Further, in the above-described embodiment, the case where one natural vibration mode is provided around the oscillation shaft 17 has been described. For example, a plurality of oscillation portions are provided, and they can be torsionally vibrated in series around the oscillation shaft 17. In the vibration system that is elastically supported, there are plural natural vibration modes. Also in this case, the frequency of the plurality of natural vibration modes can be adjusted by adjusting the moment of inertia of each oscillating portion by the same manufacturing method as in the above embodiment. Further, unnecessary vibration can be reduced by adjusting the position of the center of gravity of each swinging portion.

(Second embodiment)
4, 5 and 6 are views showing an optical deflector which is a second embodiment of the oscillator device of the present invention. 4A is a top view, and FIG. 4B is a top view of the vibration system viewed from the back side of FIG. 4A. 5 and 6 show cross-sectional views taken along the lines CC and DD in FIG. 4, respectively. In these drawings, portions having the same functions as those of the first embodiment are denoted by the same reference numerals. Hereinafter, detailed description of the functional unit is omitted, and particularly different portions will be described in detail.

As shown in FIG. 4, unlike the first embodiment, the optical deflector of this embodiment has only one elastic support portion 12, and the vibration system is fixed to the fixed body 150 in a cantilever structure. ing.

Furthermore, in this embodiment, the mass adjuster 19 is made of resin, and is installed on the surface opposite to the surface on which the permanent magnet 151 of the flat plate-like movable element 11 is installed. Therefore, the deviation of the center of gravity of the oscillating portion 41 from the oscillating shaft 17 can be reduced relatively easily, and unnecessary vibration can be reduced. That is, as shown in FIG. 5, the permanent magnet 151 and the mass adjuster 19 are disposed on the surfaces of the movable element 11 opposite to each other with the swing shaft 17 interposed therebetween, so that the mass adjuster 19 is provided. It is possible to reduce the deviation of the center of gravity of the swing part 41 from the swing shaft 17 due to the above.

The movable element 11, the elastic support part 12, and the support 13 which are the vibration system of the present embodiment are integrally formed by single-crystal silicon anisotropic etching using an alkaline aqueous solution described later. In this embodiment, the movable element 11 and the elastic support portion 12 have a characteristic shape surrounded by a crystal equivalent surface of single crystal silicon, as shown in FIGS.

As shown in FIG. 5, the mover 11 of this embodiment has a recess 31 that extends parallel to the swing shaft 17. The recess 31 has the same effect in the step of removing the gap 30 and the mass adjuster 19 in the first embodiment with a laser beam. Then, for example, the relationship between the removed mass and the removed moment of inertia can be changed by selecting the distance and volume from the rocking shaft 17 of the portion from which the mass is removed. Therefore, it is possible to match the position of the center of gravity of the rocking portion 41 with the rocking shaft 17 while adjusting the frequency of the natural vibration mode.

Further, by forming the concave portion 31 as a gap, the gap can be formed simply by using a flat plate for the mass adjusting body 19, so that assembly for bonding is facilitated. Furthermore, since no gap is formed on the back surface on the side where the recess 31 is formed, almost the entire back surface (however, other than the portion where the permanent magnet 151 is provided) 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. Accordingly, the elastic support portion 12 has high rigidity in the directions of arrows L and M in FIG. 6, and the torsional rigidity around the swing shaft 17 in the direction of arrow N is relatively soft. That is, the torsion spring is easily twisted around the center of the swing shaft 17 and is difficult to bend in the other direction. Therefore, unnecessary vibrations in the directions of the arrows L and M can be effectively suppressed.

Further, there is only one elastic support portion 12 in the present embodiment, and the vibration system is supported on one end with respect to the fixed body 150. For this reason, even if the fixed body 150 is deformed due to a temperature change or an external force, the stress in the direction of the oscillating shaft 17 is not transmitted from the fixed body 150 to the vibration system. The frequency change of the natural vibration mode can be suppressed. Further, even if the fixed body 150 is deformed, the vibration system is hardly deformed. Accordingly, the center of gravity position adjusted to coincide with the swing shaft 17 at the time of manufacture does not change due to a temperature change or an external force, so that unnecessary vibration can be reduced regardless of the temperature change or the presence or absence of the external force.

Next, an alkaline aqueous solution etching process of the movable element 11, the elastic support part 12, and the support body 13 of the present embodiment will be described. FIGS. 8 and 9 show shapes during the alkaline aqueous solution etching corresponding to the cross sections of FIGS. 5 and 6, respectively. (A) to (f) in FIGS. 8 and 9 show the cross-sectional shapes at the same timing. First, in (a), the protective film 101 is patterned using a silicon substrate 99 having the (100) equivalent surface 100 on which the protective film 101 is formed in the direction shown in the figure. In this embodiment, the protective film 101 is a silicon nitride film. The silicon nitride film can be formed using a chemical vapor synthesis method. Further, a pattern of the protective film 101 is formed by photolithography and dry etching as shown in FIG.

Here, as shown in FIG. 8, an opening having a width Wk is formed. Further, as shown in FIG. 9, openings having widths Wb and Wg are formed. These widths can be determined from the angle formed by the (111) equivalent surface and the (100) equivalent surface appearing in a later step and the thickness of the silicon substrate 99. By setting these widths appropriately, it becomes possible to manufacture the necessary torsion spring constant and the size of the recess based on the specifications of the vibration system.

Next, in (b), etching is started by dipping in an alkaline aqueous solution. In this embodiment, an aqueous potassium hydroxide solution is used. An alkaline aqueous solution such as a potassium hydroxide aqueous solution can form a shape surrounded by the (111) equivalent surface because the etching rate of the (111) equivalent surface of single crystal silicon is slower than other surfaces. As the etching proceeds, etching is performed as shown in (b) to (f). Finally, in (f), the mover 11, the recessed portion 31, the elastic support portion 12, and the support body 13 surrounded by the (100) equivalent surface 100 and the (111) equivalent surface 102 are formed. Thereafter, the protective films 101 on both sides are removed by dry etching, and the reflective film 22 is formed in a shape as shown in FIG. 4A by vacuum vapor deposition to form a vibration system.

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

In particular, the (111) equivalent surface of single crystal silicon has a slow etching rate and can be precisely processed into the shapes of the recess 31 and the elastic support portion 12. By precisely processing the recess 31, the moment of inertia and the position of the center of gravity of the mover 11 can be determined accurately. In addition, since the elastic support portion 12 can be processed precisely, the torsion spring constant can be determined accurately. That is, the frequency of the natural vibration mode and the position of the center of gravity of the vibration system can be accurately determined. For this reason, in the process of removing a part of the mass adjusting body 19 for adjusting the frequency of the natural vibration mode and the position of the center of gravity, the processing can be performed at higher speed. In addition, the resolution of frequency adjustment can be increased by using the mass adjustment body 19 having a low density in order to perform more accurate frequency adjustment without increasing the installation area of the mass adjustment body 19.

(Third embodiment)
A third embodiment of the oscillator device of the present invention will be described. FIG. 10A is a plan view showing a third embodiment of the oscillating device including two oscillating portions provided so as to be able to oscillate around the oscillating shaft 304. FIG. In the present embodiment, the two oscillating parts are constituted by first and second movable elements 302, 320 each having protrusions 303, 321 for adjusting the mass of the oscillating part. The first armature 302 is elastically supported by the first armature support portion (torsion spring) 305 with respect to the second armature 320 so as to be capable of torsional vibration in the center of the swing shaft 304. The second mover 320 is elastically supported by the second elastic support portion (torsion spring) 306 with respect to the support 301 so as to be capable of torsional vibration at the center of the swing shaft 304.

In the present embodiment, the mass adjusters are not provided separately, but part of the movers 302 and 320 themselves are formed as protrusions 303 and 321 extending in a direction parallel to the swinging shaft 304 serving as the mass adjuster. . By cutting any portion of the protrusion with laser light, it can be removed with an appropriate volume.

The oscillator device of the present embodiment is driven by a drive means (not shown) by a combined drive signal of a reference frequency f ₀ that is a target drive frequency determined from application specifications and a frequency 2f _{0 that} is twice that frequency. The oscillator device has two natural mode frequencies f ₁ and f ₂ around the oscillation axis 304, and these are adjusted by a method described in detail later so as to substantially coincide with the frequencies f ₀ and 2f _0. Has been. Therefore, in this embodiment, the combined wave drive of the two signals having the frequencies f ₀ and 2f ₀ can be performed with low power consumption by using the high amplitude amplification factor of the natural vibration mode.

The state of synthetic wave driving will be described in detail below. FIG. 11 is a diagram for explaining the displacement angle of the torsional vibration of the first mover 302 at the frequency f _{0 with} the horizontal axis as time t. Figure shows a portion corresponding to one cycle T ₀ of the torsional oscillation of the first movable element _{302 (-T 0/2 <X} <T 0/2).

A curve 61 shows a sine wave component of the reference frequency f ₀ of the torsional vibration of the first movable element 302. The curve 61 reciprocates within the range of the maximum amplitude ± φ ₁ , and the time t and the angular frequency w ₀ = 2πf ₀ are set. This is a sine vibration expressed by the following equation 2.
θ ₁ = φ ₁ sin [w ₀ t] (Formula 2)

On the other hand, a curve 62 shows a sine wave component having a frequency twice as high as the reference frequency f ₀ , and is a sine vibration expressed by the following expression 3 that vibrates in the range of the maximum amplitude ± φ ₂ .
θ ₂ = φ ₂ sin [2w ₀ t] (Formula 3)

A curve 63 indicates a displacement angle of torsional vibration of the first mover 302 resulting from such driving. Oscillator device, a reference frequency f ₀ and 2 times the 2f ₀ of the frequency f _1, which is adjusted to near the natural oscillation mode and the second-order natural oscillation mode of frequency f ₂ of the pivot shaft 304 around its as previously described Has torsional vibration. Therefore, in the oscillator device, resonance excited by the drive signals of θ ₁ and θ ₂ occurs. In other words, the displacement angle of the first mover 302 on the curve 63 is a superposed vibration of two sinusoidal vibrations and a sawtooth vibration represented by the following equation 4.
θ = θ ₁ + θ ₂ = φ ₁ sin [w ₀ t] + φ ₂ sin [2w ₀ t] (Formula 4)

FIG. 12 shows curves 61a and 63a and a straight line 64a obtained by differentiating the curves 61 and 63 and the straight line 64 of FIG. 11, and the angular velocities of these curves are explained. Compared with the curve 61a which depicts the angular speed of sinusoidal oscillation of the reference frequency f _0, the curve 63a that indicates the angular velocity of the sawtooth reciprocating movement of the first movable element 302, in the section N-N ', the angular velocity V ₁ of the maximum point, angular velocity range of the angular velocity V ₂ of the minimum point and the maximum and minimum is seated. Therefore, in an application in which a reflecting surface is formed on the first movable element 302 and light deflection scanning is used, if V ₁ and V ₂ exist within the tolerance of the angular velocity from the straight line 64a that is a constant angular velocity scan, The section NN ′ can be regarded as a substantially equiangular light scanning.

In this manner, the angular velocity of scanning can be set wide by a sawtooth reciprocating vibration compared to when the displacement angle is a sine wave. The area can be enlarged. Furthermore, when forming a spot, the modulation circuit can be simplified because it is not necessary to take into account the non-uniformity of angular velocity in the modulation timing of the light source.

In addition, since the change in angular acceleration due to rocking is small, deformation of the reflecting surface during driving can be reduced. Since each scanning line is equally spaced, it is suitable for applications such as printers.

Although it has been described above that the frequencies of the natural vibration modes of f ₁ and f ₂ have a substantially double relationship, they can be substantially tripled. In that case, as in the case where the relationship between the two frequencies is doubled, the vibration of the superposition of the sine waves results in a triangular wave-like vibration. According to this, since reciprocal use of optical scanning becomes possible, the number of usable scanning lines at a certain frequency can be doubled.

By the way, in the oscillator device that drives by driving two or more natural vibration modes in the torsional vibration direction simultaneously, the smaller the mode damping ratio of each mode, the lower the power consumption. On the other hand, when the mode damping ratio is small, the setting range of the frequencies of the plurality of natural vibration modes to be driven (the frequencies f ₁ and f _{2 in} the optical deflector of this embodiment) is narrowed. Therefore, in order to reduce the power consumption of the optical deflector, it is necessary to accurately adjust the frequencies of the plurality of natural vibration modes.

A method for adjusting the frequencies f ₁ and f ₂ of the natural mode to the frequencies f ₀ and 2f ₀ will be described with reference to FIG. FIG. 13 is an enlarged top view of the first movable element 302 and the protruding portion 303 of the oscillator device shown in FIG. 10 (a). A central axis C passing through the protrusion 303 passes through the center of the thickness of the protrusion 303 (the length in the normal direction of the paper surface) and is parallel to the swing shaft 304. The protrusion 303 has the same cross-sectional shape (cross-sectional area) with the central axis C as a normal line regardless of the position. That is, the cross-sectional shapes at the position A and the position B are the same.

The protrusion 303 has a volume to be removed adjusted in accordance with a residual from the reference frequency f ₀ (or 2f ₀ ) of the frequency f ₁ (or frequency f ₂ ). At this time, the protruding portion 303 is cut by a cross section having the central axis C as a normal line, and the removal amount is adjusted by adjusting the position of the cutting portion. In this manner, the protrusion 303 is removed at the position A or the position B according to the frequency residual. The removed moments of inertia of length La and length Lb are equal to the product of the removed mass and the square of the distance Dc between the center axis C and the swing shaft 304, and the ratio of the moment of inertia adjustment by the positions A and B Is equal to the ratio of the lengths La and Lb. Therefore, since the removal amount is proportional to the length, the removal amount can be estimated quickly.

In addition, since a portion larger than the laser processing region from the position of the cutting portion to the tip of the protruding portion is removed, it is possible to perform rapid removal. This not only shortens the time required for processing, but also suppresses the transfer of heat to the oscillator device during laser processing, thereby preventing damage and modification of the oscillator device due to heat. Furthermore, since the dust generated from the processed part during laser processing can be reduced, contamination of the oscillator device can be prevented. Since the laser processing length required for the removal amount becomes the same regardless of the position A and the position B, both the required processing time and the processing movement amount (processing laser scanning amount or processing stage movement amount) are constant, The moving body device can be adjusted at a low cost.

Further, the protrusions 303 and 321 formed on the first movable element 302 and the second movable element 320 are both configured in parallel with the swing shaft 304. Therefore, since the cutting directions of the protrusions 303 and 321 are parallel to each other, the laser processing direction may be the same, and the processing apparatus is simplified. Thus, a processing error occurs in the first elastic support portion 305, the second elastic support portion 306, etc., and the frequencies f ₁ and f _{2 of the} two eigenmodes have a large residual from the frequencies f ₀ and 2f _0. Each frequency can be adjusted.

(Fourth embodiment)
A fourth embodiment of the oscillator device of the present invention will be described. FIG. 10B is a top view showing the mass adjusting body 419 installed on the mover provided so as to be swingable around the swing axis. In the mass adjusting body 419 of the present embodiment, a plurality of protruding portions 420 are formed by protruding onto the gap 430 and extending a part of the mass adjusting body. Here, in order to adjust the natural vibration mode frequency around the swing axis to the target frequency and to adjust the center of gravity position of the swing portion to the swing axis, the base of the protrusion 430 is cut with a laser beam. Then, an appropriate number of protrusions 430 are removed with an appropriate volume. In FIG. 10B, the cut points are indicated by broken lines. If you set the position (distance from the swing axis) and mass of the protrusion, you can know in advance how much the moment of inertia and center of gravity can be adjusted when this protrusion is cut off. Can be adjusted very quickly and accurately.

(Fifth embodiment)
FIGS. 14, 15, and 16 are views showing a fifth embodiment of the optical deflector which is an example of the oscillator device of the present invention. 14 is a top view showing a vibration system of the optical deflector, FIG. 15 is a top view showing a drive substrate having a drive means for driving the vibration system, and FIG. 16 is a structure of FIG. 14 in which the vibration system and the drive substrate are assembled. It is sectional drawing in the AA line. In this embodiment, the protrusions 503a, 503b, 503c, and 503d are formed on the movable element 513 as shown in the figure, and constitute a swinging portion. The vibration system includes an oscillating portion, an elastic support portion 512, and a support body 511. The mover 513 is, for example, 1.5 mm in the direction perpendicular to the swing shaft 517 and 1 mm in the parallel direction.

In this embodiment, two movable elements 513 are elastically supported by a pair of elastic support portions 512 so as to be able to torsionally vibrate around a swing shaft 517. The protrusions 503a and 503b and the protrusions 503c and 503d are connected to the movable element 513 at symmetrical positions as shown in the figure with the swing shaft 517 interposed therebetween. All the protrusions are formed so as to extend in a direction parallel to the swing shaft 517. Further, when comparing the pair of protrusions 503a and 503b or the protrusions 503c and 503d, the lengths of the protrusions are different. That is, the shape of the protrusion connected at the symmetrical position is asymmetric with respect to the swing shaft 517.

FIG. 15 shows a drive substrate 518 and drive electrodes 519 which are drive means. As shown in the figure, the drive electrode 519 is formed symmetrically with respect to the swing shaft 517. Further, as shown in FIG. 16, the drive substrate 518 and the vibration system are assembled with a spacer 520 for making an appropriate interval therebetween. Thus, the mover 513 is opposed to the drive electrode 519 through the gap. The mover 513 is electrically grounded. Accordingly, by alternately applying a high voltage to the drive electrodes 519 arranged symmetrically, an electrostatic attractive force is generated between the mover 513 and the drive electrode 519 to which the voltage is applied. Therefore, a torque around the swing shaft 517 is generated and the vibration system can be driven.

The driving principle of the optical deflector of this embodiment is also as described in the first embodiment. However, the frequency f ₁ may deviate from the reference frequency f ₀ due to various error factors such as material property variations and processing tolerances. In the configuration of FIG. 14, a processing error part 400 is generated due to a mask shape error during dry etching. Unintentional factors in the semiconductor manufacturing process cause such processing errors, leading to a decrease in product yield. The processing error portion 400 may be a projection-like shape error as shown in the drawing, a concave portion, or a dust-fixed portion.

Such a processing error part 400 becomes an error factor of the inertia moment of the entire swinging part. Under such circumstances, as can be seen from the above equation 1, an error also occurs in the frequency f ₁ of the natural vibration mode of the vibration system, so that a good amplitude gain cannot be obtained. Further, the processing error part 400 offsets the center of gravity position of the entire swinging part in an unintended direction from the design position. When such an offset distance is generated, undesirable unwanted fluctuations occur in the vibration of the vibration system, resulting in an inclination error of the reflecting surface of the mover 513, and the scanning characteristics are deteriorated.

In an ideal state where there is no center-of-gravity shift, the mover 513 is torsionally oscillated around the swing shaft 517 by the drive signal having the frequency f ₀ . On the other hand, when the center of gravity deviates from the swing shaft 517, an inertial force is generated in the mover from the swing shaft 517 toward the center of gravity due to torsional vibration. The inertial force causes unnecessary vibration having a characteristic frequency in the offset direction of the center of gravity. For this reason, the scanning characteristics are deteriorated.

By adjusting both the frequency f ₁ of the natural vibration mode and the offset distance of the center of gravity, it is possible to prevent the deterioration of scanning characteristics and to obtain an optical deflector with low power consumption. A method of simultaneously adjusting the natural vibration mode frequency f ₁ and the offset distance of the center of gravity of the oscillating portion will be described with reference to FIG. 13 used in the description of the third embodiment. Here, in FIG. 13, reference numeral 302 is the mover 513 in FIG. 14, and reference numeral 303 is the protrusion 503c in FIG.

A central axis C passing through the protruding portion 503c passes through the center of the thickness of the protruding portion 503c (length in the normal direction of the paper surface) and is parallel to the swing shaft 517. The protrusions 503c have the same cross-sectional shape with the central axis C as a normal line regardless of the position. That is, for example, the cross-sectional shapes at the position A and the position B are equal. The protruding portion 503c has a volume to be removed adjusted in accordance with a residual between the frequency f _{1 and} the reference frequency f ₀ and an offset distance of the center of gravity. At this time, the protruding portion 503c is cut by a cross section having the central axis C as a normal line, and the removal amount is adjusted by adjusting the position of the cutting portion.

The protruding portion 503c is removed at the position A or the position B by irradiating the laser beam. The removed length La or the inertia moment of the length Lb is equal to the product of the square of the distance Dc between the central axis C and the swing shaft 517 and the removed mass. Since the removal amount is proportional to the length, the ratio of the adjustment amount of the moment of inertia due to the removal at the position A and the position B 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 symmetrical positions with the swing shaft 517 interposed therebetween. FIG. 14 shows the structure after a part of the protrusion is removed by the above method. Before the removal, the pair of protrusions 503a and 503b and the protrusions 503c and 503d have the same width. And can have a length. Therefore, the protrusions 503a and 503b and the protrusions 503c and 503d in FIG. 14 have different removal lengths, and by adjusting this ratio, the offset distance of the center of gravity of the swinging part can be adjusted. .

In this embodiment, first, the frequency of the natural vibration mode of the vibration system is measured, and the adjustment amount of the moment of inertia to the design value is estimated. This frequency measurement can be performed based on the detection information of the scanning beam by the light receiving element, the detection information by the piezoresistor provided on the elastic support portion or the like. From the estimated amount, the sum of the lengths of the protrusions 503a, 503b, 503c, and 503d to be removed is determined. In the manufacturing method of the oscillator device of this embodiment having at least one natural oscillation mode around the oscillation axis, this process includes the following steps. That is, it includes a step of measuring the frequency of the natural vibration mode around the rocking axis of the rocking body device and a step of determining the total removal amount of the plurality of protrusions based on this frequency.

Thereafter, the ratio of the removal lengths of the pair of protruding portions 503a and 503b or the protruding portions 503c and 503d is determined according to the offset distance of the center of gravity. In this embodiment, the offset distance of the center of gravity can be estimated from the residual from the ideal scanning locus by measuring the scanning locus of the light beam. In the manufacturing method of the oscillator device of this embodiment having at least one natural oscillation mode around the oscillation axis, this process includes the following steps. That is, the step of driving the oscillator device, the step of detecting the oscillation mode or drive waveform of the oscillation unit of the oscillator device, the oscillation mode is compared with the target oscillation mode, Determining the ratio of the removal amounts of the protrusions so that the offset distance is reduced.

The process including the sum determining step and the removal amount ratio determining step can be summarized as a step including the following steps. That is, the step of driving the rocking body device, the step of detecting the rocking mode of the rocking part of the rocking body device, and this rocking mode are compared with the target rocking mode. Including a step including a step of determining a removal form.

By changing the laser irradiation position according to the removal length determined as described above, the protrusions 503a, 503b, 503c, and 503d are processed into shapes having asymmetric lengths with the swing shaft 517 interposed therebetween. In this way, in the present embodiment, it is possible to simultaneously adjust the frequency of the natural vibration mode and the offset distance of the center of gravity. In particular, in this embodiment, the amount of inertia adjustment is proportional to the machining length, so that the machining target value can be determined quickly.

(Sixth embodiment)
A sixth embodiment of the oscillator device and the manufacturing method thereof according to the present invention will be described. FIG. 17 is a plan view showing an embodiment of an oscillating device including two oscillating portions provided so as to be oscillatable around the oscillating shaft 604. FIG. In the present embodiment, the two oscillating parts are constituted by first and second movable elements 602 and 620 each having a first projecting part 603 and a second projecting part 621 for adjusting the mass of the oscillating part. Has been. The first movable element 602 is elastically supported by the first movable support 620 (torsion spring) 605 with respect to the second movable element 620 so as to be capable of torsional vibration at the center of the swing shaft 604. Further, the second movable element 620 is elastically supported by the second elastic support portion (torsion spring) 606 with respect to the support body 601 so as to be capable of torsional vibration at the center of the swing shaft 604. The permanent magnet 651 is fixed to the second movable element 620. Permanent magnets 651 are respectively installed on the surface shown in FIG. 17 and the opposite surface.

In this embodiment, a part of the first movable element 602 and the second movable element 620 itself is formed as protrusions 603 and 621 extending in a direction parallel to the swing shaft 604. Similar to the fifth embodiment, the protrusions 603 and 621 are formed in a symmetrical shape at a symmetrical position with respect to the swing shaft 604. Similarly to the fifth embodiment, by cutting an arbitrary portion of the protruding portion with laser light, an asymmetrical length of an appropriate volume is removed from each protruding portion.

The first mover 602 and the first protrusion 603 constitute a first swing part, and the second mover 620, the second protrusion 603, and the permanent magnet 651 constitute a second swing part. Each oscillating portion can oscillate integrally around the oscillating shaft 604.

The oscillator device of the present embodiment includes a permanent magnet 651 as a driving means and a fixed coil based on a combined drive signal of a reference frequency f ₀ that is a target drive frequency determined from application specifications and a frequency 2f _{0 that} is twice that frequency. Driven by 652. 18 is a cross-sectional view taken along line AA in FIG. As shown in FIG. 18, the fixed coil 652 generates a magnetic field in the H direction. This magnetic field acts on the permanent magnet 651 installed on the second mover, thereby generating a torque around the swing shaft 304 and driving the vibration system.

The oscillator device has two natural mode frequencies f ₁ and f ₂ around the oscillation axis 604, and these are adjusted so as to substantially coincide with the reference frequency f ₀ and twice the frequency 2f ₀ thereof. Has been. Therefore, in this embodiment, the combined wave drive of the two signals of the frequencies f ₀ and 2f ₀ can be performed with low power consumption by using the high amplitude amplification factor of the natural vibration mode. The state of this synthetic wave drive is as described with reference to FIGS. 11 and 12 in the description of the third embodiment.

In the present embodiment, since the frequencies f ₁ and f ₂ of the two natural vibration modes that the vibration system has around the swing shaft 604 have an integer multiple relationship, the inertia of the first swing portion and the second swing portion The moment needs to satisfy the relationship of Equation 5 below.
I ₂ / I ₁ ≧ 4n ² / (n ⁴ -2n ² +1) (Formula 5)
Here, I ₁ and I ₂ are the moments of inertia of the first oscillating part and the second oscillating part, respectively, and n is an integer of f ₂ / f ₁ .

In the vibration system of the present embodiment, the frequencies f ₁ and f ₂ have a double relationship, and the relationship of the following equation 6 is established.
I ₂ / I ₁ ≧ 1.78 (Formula 6)

Therefore, in this embodiment, the second oscillating portion has a larger moment of inertia than the first oscillating portion. By installing the permanent magnet 651 as the driving means only on the second movable element 620, such a magnitude relationship of the moment of inertia is effectively created. In this way, the permanent magnet 651 creates a swinging part configuration suitable for realizing two natural vibration modes having a double frequency relationship.

Here, let us consider a case where the permanent magnet 651 is bonded and installed by shifting to the left side as shown in FIG. 17 and FIG. The center of gravity 668 of the permanent magnet 651 is offset to the left from the swing shaft 604. On the other hand, as shown in FIG. 17, the protrusion 621 has a larger removal amount of the protrusion on the side where the permanent magnet 651 is displaced. The ratio of the removal length of the protrusion 621 that is asymmetric with respect to the swing shaft 604 is determined by, for example, the method for measuring the scanning trajectory described in the fifth embodiment.

The center of gravity 669 indicates the center of gravity of the second mover including the protruding portion 621 that has been removed with an asymmetric length. A line segment connecting the center of gravity 668 and the center of gravity 669 passes through the swing shaft 604. The ratio of the offset distance between the center of gravity of the permanent magnet 651 and the second mover 620 from the swing shaft 604 is substantially equal to the ratio of the reciprocal of the mass of the permanent magnet 651 and the second mover 620. Due to such a relationship, the center of gravity of the entire second oscillating portion is disposed on the oscillating shaft 604.

As described in the fifth embodiment, other factors such as machining errors can be considered as the factors that cause the center of gravity to be offset from the rocking shaft 604. In any case, the center of gravity is offset by the method of this embodiment. The offset distance of the center of gravity of the moving part can be adjusted.

In the case of a multi-degree-of-freedom vibration system, the above-described unnecessary vibration due to the offset of the center of gravity of the oscillating portion causes coupling between a plurality of natural vibration modes and greatly deteriorates scanning reproducibility. In particular, in this embodiment, the frequencies of the two natural vibration modes have a double relationship. The frequency of the above-described unnecessary vibration is twice the basic frequency and matches the frequency of the other natural vibration mode. Therefore, the two natural vibration modes are relatively strongly coupled. Therefore, scanning reproducibility deteriorates in addition to the bending of the scanning locus.

In this embodiment, the protrusions 603 and 621 are removed asymmetrically, thereby simultaneously adjusting the two frequencies f ₁ and f ₂ of the vibration system having two natural vibration modes and the offset distance of the center of gravity of the two oscillating parts. Is possible. Therefore, it is possible not only to realize synthetic wave driving with low power consumption but also to realize good scanning characteristics. In this way, the moment of inertia of the swinging portion and the position of the center of gravity can be adjusted quickly at the same time.

(Seventh embodiment)
FIG. 19 is a schematic perspective view showing an embodiment of an optical apparatus using the optical deflector of the present invention. Here, an image forming apparatus is shown as an optical apparatus. In FIG. 19, reference numeral 3003 denotes an optical deflector according to the present invention. In this embodiment, incident light is scanned one-dimensionally. Reference numeral 3001 denotes a laser light source. 3002 is a lens or lens group, 3004 is a writing lens or lens group, and 3005 is a drum-shaped photoconductor.

The laser light emitted from the laser light source 3001 is subjected to predetermined intensity modulation related to the timing of light deflection scanning. This intensity-modulated light is scanned one-dimensionally by an optical scanning system (optical deflector) 3003 through a lens or lens group 3002. The scanned laser light forms an image on the photoreceptor 3005 by a writing lens or a lens group 3004.

The photosensitive member 3005 rotated around the rotation axis in a direction perpendicular to the scanning direction is uniformly charged by a charger (not shown), and by scanning light thereon, an electrostatic latent image is formed on the scanning portion. Is formed. Next, a toner image is formed on the image portion of the electrostatic latent image by a developing device (not shown), and an image is formed on the paper by, for example, transferring and fixing the toner image on the paper (not shown).

With the optical deflector 3003 of the present invention, an optical deflector that is well adjusted to a desired frequency can be used. Therefore, since it can be driven with a high amplitude amplification factor, it can be reduced in size and power consumption. In addition, the angular velocity of light deflection scanning on the photosensitive member 3005 can be set to a substantially constant angular velocity within a specification range. Furthermore, by using the optical deflector of the present invention, the scanning position fluctuation is reduced and an image forming apparatus capable of generating a clear image is obtained.

11, 302, 320, 513, 602, 620
12,305,306,512,605,606 Elastic support (torsion spring)
13, 301, 511, 601 Support
17, 304, 517, 604 Oscillating shaft
19, 419 Mass adjuster
22 Light deflection element (reflection surface)
30, 31, 430 Air gap (recess)
41 Swing part
61, 61a curve
62 Curve
63, 63a curve
64, 64a straight line
80 Laser light (processing laser spot)
85 Mass removal part
151, 651 Driving means (permanent magnet)
152, 652 Driving means (fixed coil)
303, 321, 503, 603, 621 Projection of mover
420 Protrusion of mass adjustment body
519 Drive means (drive electrode)
3001 Light source (laser light source)
3003 Optical deflector (optical scanning system)
3005 Photoconductor

Claims (17)

A method of manufacturing a rocking body device comprising a rocking part, an elastic support part, and a support body, wherein the rocking part is supported by the elastic support part so as to be rockable about a rocking axis,
The swing part is composed of a mover having a protrusion for adjusting the mass of the swing part, and the protrusion protrudes from the mover in a direction parallel to the swing axis,
Wherein by irradiating a laser beam to the projecting portion, have a step of removing with the projecting portions of the above in an appropriate volume from the cutting unit to the laser beam is irradiated,
Adjusting the moment of inertia of the oscillating portion and the offset distance of the center of gravity of the oscillating portion from the oscillating shaft by removing the protruding portion;
The manufacturing method of the oscillator device characterized by the above-mentioned. The method of manufacturing an oscillator device according to claim 1, wherein in the step of removing the protrusion, the protrusion is removed from a root portion of the protrusion. The oscillator device has at least one natural vibration mode around the oscillation axis,
Removal of the projecting portion, performs adjustment of the frequency of the natural oscillation mode,
The manufacturing method of the oscillator device according to claim 1 or 2. The oscillator device has two natural vibration modes around the oscillation axis,
By adjusting the frequency of the two natural vibration modes to the target frequency by removing the protrusion,
A method for manufacturing an oscillator device according to any one of claims 1 to 3. A method of manufacturing a rocking body device comprising a rocking part, an elastic support part, and a support body, wherein the rocking part is supported by the elastic support part so as to be rockable about a rocking axis,
The swing part is composed of a mover having a plurality of protrusions for adjusting the mass of the swing part,
The protrusions are disposed on opposite sides of the swing shaft,
Have a step of removing with the projecting portion in a suitable volume,
Adjusting the moment of inertia of the oscillating portion and the offset distance of the center of gravity of the oscillating portion from the oscillating shaft by removing the protruding portion;
The manufacturing method of the oscillator device characterized by the above-mentioned. The protrusions are arranged in pairs at positions symmetrical to the swing axis,
The protrusions at the symmetrical positions are removed from different shapes.
The method for manufacturing an oscillator device according to claim 5 . The plurality of protrusions protrude from the mover in a direction parallel to the swing axis,
A cross-sectional area of the protruding portion with the swing axis as a normal line is constant in the swing axis direction;
The protrusions arranged on the opposite sides with respect to the rocking shaft are removed from each other in different lengths in the rocking shaft direction.
The manufacturing method of the oscillator device according to claim 5 or 6 . By irradiating the protrusion with laser light, the cutting part irradiated with the laser light is removed including the protrusion.
A method for manufacturing an oscillator device according to any one of claims 5 to 7 . Driving the oscillator device;
Detecting a swing mode of the swing unit of the swing body device;
Comparing the swing mode with a target swing mode, and determining a removal form of the protrusion based on a comparison result;
A method for manufacturing an oscillator device according to any one of claims 5 to 8 . The oscillator device has at least one natural vibration mode around the oscillation axis,
Measuring the frequency of the natural vibration mode around the rocking axis of the rocking body device;
Determining a sum of removal amounts of the plurality of protrusions based on the frequency;
Determining the ratio of the removal amount of each of the protrusions so that the offset distance is reduced.
A method for manufacturing an oscillator device according to any one of claims 5 to 9 . An oscillating device comprising an oscillating portion, an elastic support portion, and a support body, wherein the oscillating portion is supported by the elastic support portion so as to be oscillatable about an oscillation axis,
The swing part is composed of a mover having a plurality of protrusions for adjusting the mass of the swing part,
The protrusions are arranged in pairs at symmetrical positions with respect to the swing axis, are formed to be removable with an appropriate volume,
The protrusions at the symmetrical positions are different in shape from each other,
The center of gravity of the swing part is on the swing axis,
An oscillator device characterized by the above. The plurality of protrusions protrude from the mover in a direction parallel to the swing axis,
A cross-sectional area of the protruding portion with the swing axis as a normal line is constant in the swing axis direction;
The protrusions at positions symmetrical to the swing axis are different from each other in length in the swing axis direction.
The oscillator device according to claim 11 . A coil and a permanent magnet for driving the swinging portion;
The swing part has the permanent magnet,
The center of gravity of the permanent magnet and the center of gravity of the mover are offset with respect to the swing axis;
The oscillator device according to claim 11 or 12 , wherein the oscillator device is provided. Including a vibration system and drive means for driving the vibration system;
The vibration system includes a first swing part, a first elastic support part, a second swing part, a second elastic support part, and a support,
The first swing part is composed of a first mover having a plurality of first protrusions for adjusting the mass of the first swing part,
The second swing part is composed of a second mover having a plurality of second projecting parts for adjusting the mass of the second swing part,
The plurality of first projecting portions and the plurality of second projecting portions are respectively symmetrical with respect to the swing axis, and the projecting portions at least one of the first projecting portion and the second projecting portion are in the symmetrical position. The shapes are different from each other, and are formed to be removable with an appropriate volume.
The center of gravity of the first swing part and the center of gravity of the second swing part are on the swing axis,
The first mover is elastically supported by the second mover so as to be swingable about the swing axis by the first elastic support portion,
The second mover is elastically supported on the support body so as to be swingable about the swing axis by the second elastic support portion,
The vibration system has at least two natural vibration modes having different frequencies around the swing axis.
An oscillator device characterized by the above. The movable element or the first movable element has an optical deflection element, and is configured as an optical deflector.
Oscillator device according to any one of claims 11 to 14, wherein the. A light source, the oscillator device according to claim 15 , comprising an optical deflector configured as an optical deflector, and a photoconductor,
The light deflector deflects light from the light source and causes at least a part of the light to enter the photoconductor;
An image forming apparatus. A light source; an optical deflector configured as an optical deflector according to claim 15 ; and an image display.
The light deflector deflects light from the light source and causes at least a part of the light to enter the image display;
An image display device characterized by that.

Images