JP2002148536A - Actuator and its driving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an actuator capable of being easily designed and manufactured and having a high degree of freedom of design. SOLUTION: The actuator 100A is provided with a fixed outer frame 102, a movable inner frame 104 arranged on the inside of the outer frame 102, a movable plate 106 arranged on the inside of the inner frame 104, a pair of 1st torsion bars 112, 114 for supporting the inner frame 104 so as to oscillate the frame 104 around a 1st axis against the outer frame 102, a pair of 2nd torsion bars 116, 118 for supporting the movable plate 106 so as to oscillate the plate 106 around a 2nd axis in non-parallel with the 1st axis against the inner frame 104, a pair of 1st permanent magnets 132, 134, a pair of 2nd permanent magnets 142, 144, and a driving coil 122 to be circulated around the inner frame 104. The resonance frequency of the 1st torsion bars 112, 114 is different from that of the 2nd torsion bars 116, 118.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator having a leaf spring structure used for an optical scanner for two-dimensional scanning.

[0002]

2. Description of the Related Art As an optical scanner for two-dimensional scanning, for example, an optical scanner using an actuator having a leaf spring structure manufactured by a semiconductor process is known. JP-A-7-1
No. 75005 discloses an electromagnetically driven actuator capable of two-dimensional swinging. The configuration of this actuator is shown in FIGS.

FIG. 9 shows a conventional actuator 2.
1 includes a frame-shaped outer movable plate 5A located inside the opening of the support substrate 2, and a flat inner movable plate 5B located inside the frame-shaped outer movable plate 5A. The outer movable plate 5A is supported on the support substrate 2 by the first torsion bar 6A.
Are supported so as to be able to swing. On the upper surface of the outer movable plate 5A, there is formed a planar coil 7A (schematically indicated by a single line in the figure) covered with an insulating layer. The plane coil 7A is electrically connected to a pair of outer electrode terminals 9A formed on the upper surface of the support substrate 2 via one portion of the first torsion bar 6A.

The inner movable plate 5B has a second torsion bar 6 whose axis is orthogonal to the first torsion bar 6A.
B supports the outer movable plate 5A swingably with respect to the outer movable plate 5A. On the upper surface of the inner movable plate 5B, there is formed a planar coil 7B (schematically indicated by a single line in the figure) covered with an insulating layer. The planar coil 7B is electrically connected to the inner electrode terminal 9B formed on the support substrate 2 from one side of the second torsion bar 6B, through the outer movable plate 5A, and via the other side of the first torsion bar 6A. ing. A total reflection mirror 8 is formed at the center of the inner movable plate 5B surrounded by the planar coil 7B.

FIG. 10 and FIG.
As shown in FIG. 2, upper and lower glass substrates 3 and 4 each made of, for example, borosilicate glass are anodically bonded. The upper glass substrate 3 has a square opening 3a at the center of the flat plate portion, and a portion above the total reflection mirror 8 is open. The lower glass substrate 4 has a flat plate shape. Also,
The support substrate 2 has a three-layer structure, and has two movable plates 5A and 5B.
Is formed from the intermediate layer in order to secure the swing space.

The upper and lower glass substrates 3 and 4 each have a pair of eight permanent magnets 10 each having a cylindrical shape.
A to 13A and 10B to 13B are arranged as shown. The permanent magnets 1 facing each other on the upper glass substrate 3
0A and 11A are permanent magnets 10B and 1 of the lower glass substrate 4, respectively.
1B generates a magnetic field for driving the outer movable plate. Also,
The permanent magnets 12A of the upper glass substrate 3 facing each other,
13A is a permanent magnet 12B, 13B of the lower glass substrate 4.
This generates a magnetic field for driving the inner movable plate.

FIGS. 12 and 13 show waveforms of drive signals for this actuator. The drive signal shown in FIG. 12 has a relatively high frequency, which is applied, for example, to the inner electrode terminal 9B. By applying the drive signal, Lorentz force is generated in the planar coil 7B, and the inner movable plate 5B swings around the torsion bar 6B. On the other hand, the drive signal shown in FIG. 13 has a relatively low frequency, which is applied to, for example, the outer electrode terminal 9A. By applying the driving signal, Lorentz force is generated in the planar coil 7A, and the outer movable plate 5A swings around the torsion bar 6A. The inner movable plate 5B is two-dimensionally driven by the two swinging operations around these two sets of torsion bars.

[0008]

The prior art actuator described here has a planar coil for driving on each of the inner movable plate and the outer movable plate, and each of these planar coils has a separate coil. The two-dimensional drive of the inner movable plate 5B is achieved by applying the drive signal of For this reason, in the conventional actuator, a planar coil for driving is formed on the inner movable plate and the outer movable plate, and
Wiring and electrode terminals for enabling supply of drive signals to these need to be formed.

In this actuator, since such a large number of planar coils and wirings are provided on the movable plate and the torsion bar, the design and manufacturing are complicated, and the degree of freedom in design is low. In addition, since a planar coil for driving is provided on each of the inner movable plate and the outer movable plate, it is difficult to secure a place for providing an element for detecting the position and speed of these movable plates. This, in other words, hinders downsizing of the movable part, which limits support for high-speed scanning.

An object of the present invention is to provide an actuator which is easy to design and manufacture and has a high degree of freedom in design, and also to provide an actuator which can respond to scanning at a higher speed. . Yet another object of the present invention is to provide a method for driving such an actuator.

[0011]

SUMMARY OF THE INVENTION In one aspect, the present invention is an actuator suitably used for an optical scanner for two-dimensional scanning, comprising: a fixed outer frame fixedly supported; , A movable plate located inside the movable inner frame, a first torsion bar connecting the fixed outer frame and the movable inner frame, A first torsion bar swingably supported around one axis, and a second torsion bar connecting the movable inner frame and the movable plate, wherein the movable plate is moved around the second axis with respect to the movable inner frame. A second torsion bar swingably supported on the movable inner frame and the movable plate, and a magnetic field generating means for applying a static magnetic field to the drive coil. Axis and the second axis are non-parallel to each other and the first Yonba a second torsion bars have different resonant frequencies.

The present invention, in another aspect, is a method for driving such an actuator,
This driving method supplies an alternating current including a high frequency component and a low frequency component to a driving coil. Thereby, the movable plate is rocked around the first axis and the second axis at different frequencies.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment As shown in FIG. 1, an actuator 100A according to a first embodiment includes a fixed outer frame 102 fixedly supported.
And a movable inner frame 104 located inside the fixed outer frame 102.
And a movable plate 106 located inside the movable inner frame 104;
A pair of first torsion bars 112 and 114 connecting the fixed outer frame 102 and the movable inner frame 104 and a pair of second torsion bars 1 connecting the movable inner frame 104 and the movable plate 106.
16 and 118 are provided. This leaf spring structure is integrally formed from a semiconductor substrate by a micromachine manufacturing method.

The movable inner frame 104 is swingably supported with respect to the fixed outer frame 102 by a pair of first torsion bars 112 and 114, and the movable plate 106 is formed by a pair of second torsion bars 116 and 118. Accordingly, the movable inner frame 104 is swingably supported by the movable inner frame 104. A pair of first torsion bars 112 and 114 and a pair of second torsion bars 1
16, 118 extend in directions different from each other, for example, directions orthogonal to each other. Accordingly, the movable plate 106 is moved relative to the fixed outer frame 102 by a pair of the first torsion bars 1.
12, 114 may swing together with the movable inner frame 104 about a first axis extending along the pair of second torsion bars 116, 118 alone. Can rock.

The movable plate 106 has a total reflection mirror on its back surface, that is, the surface corresponding to the back side in FIG. 1, and is swung relatively fast around one of a first axis and a second axis. Swinged relatively slowly about one axis and the other of the second axis. For this reason, one of the first torsion bars 112, 114 and the second torsion bars 116, 118 has a relatively high resonance frequency suitable for high-speed oscillation, and the first torsion bars 112, 114 And the other of the second torsion bars 116, 118 have a relatively low resonance frequency suitable for low speed rocking.

For example, in an actuator applied to image formation by the NTSC system, the resonance frequency of the torsion bar on the high-speed oscillation side is set to 14.3 kHz.
The resonance frequency of the torsion bar on the low-speed swing side is set to 30 Hz or 60 Hz. Therefore, in a preferred example, the torsion bar on the high-speed oscillation side is made of a semiconductor material such as single crystal silicon, and the torsion bar on the low-speed oscillation side is made of an organic insulating material such as polyimide.

The production of a leaf spring structure in which one torsion bar is made of single-crystal silicon and the other torsion bar is made of polyimide is disclosed in detail in JP-A-10-020226 by the present applicant. .

The actuator 100A further comprises a pair of first permanent magnets 132, 134 for providing a static magnetic field parallel to the stationary movable plate 106 and extending along a second axis;
A pair of second permanent magnets 142, 144 for providing a static magnetic field parallel to the stationary axis and extending along the first axis
A drive coil 122 that circulates around the movable inner frame 104; a first Hall element 152 for detecting a swing position, ie, a tilt position, of the movable plate 106 around the first axis; A second Hall element 154 for detecting the swing position, that is, the tilt position of the plate 106 is provided.

The pair of first permanent magnets 132, 134
Preferably, they are coupled to yokes 136, 138, respectively. Similarly, a pair of second permanent magnets 142, 144
Are preferably coupled to yokes 146, 148, respectively. The yoke may be omitted if a sufficiently strong magnetic field can be obtained without it. Instead of arranging two pairs of permanent magnets in accordance with two pairs of opposite sides of the leaf spring structure, a pair of permanent magnets may be arranged in the diagonal direction of the leaf spring structure.

One end of the drive coil 122 is electrically connected to an electrode pad 124 provided on the fixed outer frame 102, and the other end of the drive coil 122 is also provided on the fixed outer frame 102. Is electrically connected to another electrode pad 126. The driving coil 122 is supplied with an alternating current including a high frequency component and a low frequency component, or, in other words, an alternating current having a double period through a pair of electrode pads 124 and 126.

The movable inner frame 104 passes through the pair of first torsion bars 112 and 114 by Lorentz force generated by interaction between the current flowing through the drive coil 122 and the magnetic field generated by the first permanent magnets 132 and 134. Around the first axis, the first torsion bar 112, 1
It is oscillated at a frequency corresponding to the fourteen resonance frequencies fr1.
In addition, the movable inner frame 104 is driven by a current flowing through the drive coil 122 and a magnetic field generated by the second permanent magnets 142 and 144 and Lorentz force generated by interaction.
Micro-vibration is induced, and the resonance caused by this vibration of the movable inner frame 104 causes the movable plate 106 to move around the first axis passing through the pair of second torsion bars 116, 118 so that the second torsion bar 116 is moved. , 118 at a frequency corresponding to the resonance frequency fr2.

Therefore, the movable plate 106 has a frequency determined by the resonance frequency of the first torsion bars 112 and 114,
It is rocked around the first axis together with the movable inner frame 104, and is rocked alone around the second axis at a frequency determined by the resonance frequency of the second torsion bars 116, 118. That is, the movable plate 106 is driven two-dimensionally.

The first Hall element 152 includes the movable plate 106
It is located above, and is preferably located far from the first axis. The second Hall element 154 is located on the movable plate 106, and is preferably located far from the second axis.

The first Hall element 152 cooperates with a magnetic field generated by the pair of first permanent magnets 132 and 134 to correspond to a swing position, that is, a tilt position of the movable plate 106 around the first axis. Generate a signal. Further, the second Hall element 154 includes a pair of second permanent magnets 142, 144.
In cooperation with the magnetic field generated by the movable plate 106, a signal corresponding to a swing position, that is, a tilt position of the movable plate 106 around the second axis is generated. In FIG. 1, the wiring related to the Hall element is not shown.

In other words, in other words, the first Hall element 152 and the pair of first permanent magnets 132 and 134 constitute means for detecting the swing position of the movable plate 106 around the first axis. It can be said that the second Hall element 154 and the pair of second permanent magnets 142 and 144 constitute a unit that detects the swing position of the movable plate 106 around the second axis.

A technique for detecting the swinging position or the tilting position of the movable plate using such a Hall element is disclosed in detail in Japanese Patent Application Laid-Open No. 2000-81589 by the present applicant.

The AC signal supplied to the drive coil 122 includes a high-frequency component having a frequency corresponding to high-speed oscillation and a low-frequency component having a frequency corresponding to low-speed oscillation. An AC signal containing such a high-frequency component and a low-frequency component, that is, an AC current having a double cycle, is, in one example, a high-frequency component having a frequency corresponding to high-speed oscillation and a low-frequency component having a frequency corresponding to low-speed oscillation. It is an alternating current created by simply superimposing the components. However, in a more preferred example, the alternating current having a double period
Alternatively, as shown in FIG. 3, the alternating current is such that the envelope connecting the peaks of the high-frequency components corresponding to the high-speed oscillation is the low-frequency components corresponding to the low-speed oscillation.

In the alternating current shown in FIG. 2, the peak of the high-frequency component changes gradually at a constant period, and the low-frequency component consisting of an envelope connecting them has a sine waveform.
In the alternating current shown in FIG. 3, the peak of the high-frequency component changes in a binary manner at a constant period, and the low-frequency component consisting of an envelope connecting them has a rectangular waveform. Here, an example was given in which the envelope connecting the peaks of the high-frequency components was a sine waveform or a rectangular waveform, but the present invention is not limited to these, and the envelope connecting the peaks of the high-frequency components may be other than a triangular waveform. May be a periodic waveform.

In other words, the driving coil 1
The AC signal supplied to 22 includes a first AC component having a first frequency and a second AC component having a second frequency. Preferably, the first AC component has a frequency equal to the resonance frequency fr1 of the first torsion bars 112, 114, and the second AC component equals the resonance frequency fr2 of the second torsion bars 116, 118. Have a frequency.

The resonance frequency fr1 of the first torsion bars 112, 114 and the second torsion bars 116, 118
Is a design parameter determined according to the application and purpose, etc., and the first torsion bar 112,
The resonance frequency fr1 of the second torsion bar 11
6, 118 may be designed to be higher than the resonance frequency fr2, and conversely, the first torsion bars 112, 114
Of the second torsion bars 116 and 11
8 may be designed to be lower than the resonance frequency fr2. Therefore, the first AC component may be a high-frequency component and the second AC component may be a low-frequency component. Conversely, the first AC component is a low-frequency component and the second AC component is a high-frequency component. It may be.

The first AC component has a frequency equal to fr1 / (2n + 1), where n is a natural number, with respect to the resonance frequency fr1 of the first torsion bars 112 and 114. Is the second torsion bar 116,
For a resonance frequency fr2 of 118, m is a natural number,
It may have a frequency equal to fr2 / (2m + 1).
In this case, a slight decrease in amplitude is expected.

In summary, the first AC component has a frequency equal to fr1 / (2n-1), where n is a natural number, with respect to the resonance frequency fr1 of the first torsion bars 112 and 114, The second AC component has a frequency equal to fr2 / (2m-1) where m is a natural number with respect to the resonance frequency fr2 of the second torsion bars 116 and 118.

The first torsion bars 112, 11
4 and the second torsion bar 116,
The resonance frequency fr2 of 118 is determined in consideration of its material, dimensions such as thickness, width and length, and mass of the movable part.
Optimal design can be performed to obtain a desired value. The deflection angles of the movable plate 106 around the first axis and the second axis are the length and number of turns of the coil facing the permanent magnet, the interval between the permanent magnet and the drive coil facing the permanent magnet, the magnetic field strength of the permanent magnet. The length can be adjusted by adjusting the amplitude of the alternating current flowing through the drive coil. Furthermore, since the movable plate 106 is driven by resonance, the high-speed swing has no adverse effect on the low-speed swing, and conversely, the low-speed swing has no adverse effect on the high-speed swing.

The actuator 100A of the present embodiment is
It has only one drive coil 122 and the drive coil 12
2 is provided on the movable inner frame 104, so that the movable plate 1
06 is not provided with a driving coil,
Design and manufacturing are easy. Further, on the movable plate 106, an element for detecting the position, that is, a Hall element 152,
It is possible to easily secure a place where the 154 is arranged. Further, it is possible to further greatly reduce the size and weight of the movable plate 106, and it is possible to provide an actuator corresponding to scanning at higher speed.

Second Embodiment Next, an actuator according to a second embodiment will be described with reference to FIG. In FIG. 4, members substantially the same as those of the actuator of the first embodiment are denoted by the same reference numerals, and in the following description, a detailed description thereof will be omitted to avoid duplication.

As shown in FIG. 4, the actuator 100B of the second embodiment comprises a fixed outer frame 102 fixedly supported, a movable inner frame 104 located inside the fixed outer frame 102, Movable plate 1 located inside inner frame 104
06, a pair of first torsion bars 112 and 114 connecting the fixed outer frame 102 and the movable inner frame 104, and a pair of second torsion bars 116 and 118 connecting the movable inner frame 104 and the movable plate 106. Having a leaf spring structure.

The movable inner frame 104 is swingably supported with respect to the fixed outer frame 102 by a pair of first torsion bars 112 and 114, and the movable plate 106 is formed by a pair of second torsion bars 116 and 118. Accordingly, the movable inner frame 104 is swingably supported by the movable inner frame 104. Therefore, the movable plate 106
May swing with the movable inner frame 104 about a first axis extending along the pair of first torsion bars 112, 114 with respect to the fixed outer frame 102, and may include a pair of second It may swing alone about a second axis extending along the torsion bars 116,118.

The actuator 100B further includes a pair of first permanent magnets 132, 134 for applying a static magnetic field parallel to the stationary movable plate 106 and extending along the second axis;
A pair of second permanent magnets 142, 144 for providing a static magnetic field parallel to the stationary axis and extending along the first axis
, A drive coil 122 that circulates around the movable inner frame 104, and a speed detection coil 162 for detecting the swing speed of the movable plate 106.

The pair of first permanent magnets 132, 134
Preferably, they are coupled to yokes 136, 138, respectively. Similarly, a pair of second permanent magnets 142, 144
Are preferably coupled to yokes 146, 148, respectively.

One end of the drive coil 122 is electrically connected to an electrode pad 124 provided on the fixed outer frame 102, and the other end of the drive coil 122 is also provided on the fixed outer frame 102. Is electrically connected to another electrode pad 126.

One end of the speed detection coil 162 is electrically connected to an electrode pad 164 provided on the fixed outer frame 102, and the other end of the speed detection coil 162 is also connected to the fixed outer frame 102. Is electrically connected to another electrode pad 164 provided on the other side.

The actuator 100B of the present embodiment is
It is driven in exactly the same way as the actuator 100A of the first embodiment. In other words, the movable plate 106 is two-dimensionally driven, that is, oscillated by supplying an AC signal including a high-frequency component and a low-frequency component, that is, an AC current having a double period, to the drive coil 122.

According to the two-dimensional swing of the movable plate 106,
As a result of the temporal variation of the magnetic flux crossing the inside of the speed detecting coil 162, an induced electromotive force is generated between the electrode pads 164 and 166 electrically connected to the speed detecting coil 162. This induced electromotive force depends on the swing speed of the movable plate 106. In other words, the induced electromotive force is
It can be said that this is a speed signal indicating a swing speed of 06. Therefore, from the induced electromotive force generated between the electrode pads 164 and 166,
The swing speed of the movable plate 106 can be known. Also, by integrating this induced electromotive force with time, the movable plate 1
The swing position of 06 can also be known.

The induced electromotive force, ie, the speed signal, reflects both the oscillation about the first axis and the oscillation about the second axis. That is, the speed signal is composed of the frequency component of fr1 and f
r2 frequency component. Therefore, by passing the speed signal through a first filter that passes a signal in a frequency band including fr1 but not including fr2, a signal corresponding to the swing speed around the first axis is selectively obtained, and ,
By passing the signal through a second filter that passes a signal in a frequency band including fr2 but not including fr1, a signal corresponding to the swing speed around the second axis can be selectively obtained.

That is, by separating the speed signal by frequency, the swing speed of the movable plate 106 around the first axis and the swing speed of the movable plate 106 around the second axis are separately obtained. Further, by temporally integrating each of these signals, the swing position of the movable plate 106 around the first axis and the swing position of the movable plate 106 around the second axis are separately obtained. .

This is, in other words, the speed detection coil 1
62, the pair of first permanent magnets 132 and 134, and the first filter constitute a unit for detecting a swing position of the movable plate 106 around the first axis, and the speed detection coil 162 and the pair of second The permanent magnets 142 and 144 and the first filter
It can be said that it constitutes means for detecting the swing position of the movable plate 106 around the second axis.

The actuator 100B of the present embodiment is
It has only one drive coil 122 and the drive coil 12
2 is provided on the movable inner frame 104, so that the movable plate 1
06 is not provided with a driving coil,
Design and manufacturing are easy. An element for detecting the speed, that is, the speed detecting coil 16 is provided on the movable plate 106.
2 can be easily secured. Further, it is possible to further greatly reduce the size and weight of the movable plate 106, and it is possible to provide an actuator corresponding to scanning at higher speed.

Third Embodiment Next, an actuator according to a third embodiment will be described with reference to FIG. In FIG. 5, members that are substantially the same as those of the actuator of the first embodiment are denoted by the same reference numerals, and in the following description, a detailed description thereof will be omitted to avoid duplication of the description.

As shown in FIG. 5, the actuator 100C according to the third embodiment includes a fixed outer frame 102 fixedly supported, a movable inner frame 104 located inside the fixed outer frame 102, Movable plate 1 located inside inner frame 104
06, a pair of first torsion bars 112 and 114 connecting the fixed outer frame 102 and the movable inner frame 104, and a pair of second torsion bars 116 and 118 connecting the movable inner frame 104 and the movable plate 106. Having a leaf spring structure.

The movable inner frame 104 is swingably supported with respect to the fixed outer frame 102 by a pair of first torsion bars 112 and 114, and the movable plate 106 is formed by a pair of second torsion bars 116 and 118. Accordingly, the movable inner frame 104 is swingably supported by the movable inner frame 104. Therefore, the movable plate 106
May swing with the movable inner frame 104 about a first axis extending along the pair of first torsion bars 112, 114 with respect to the fixed outer frame 102, and may include a pair of second It may swing alone about a second axis extending along the torsion bars 116,118.

The actuator 100C further includes a pair of first permanent magnets 132, 134 for applying a static magnetic field parallel to the stationary movable plate 106 and extending along the second axis;
And a drive coil 122 that circulates around the movable inner frame 104. One end of the drive coil 122 is fixed to the fixed outer frame 10.
2, and the other end of the drive coil 122 is electrically connected to another electrode pad 126 also provided on the fixed outer frame 102.

The actuator 100C of the present embodiment is
It is driven in exactly the same way as the actuator 100A of the first embodiment. In other words, the movable plate 106 is two-dimensionally driven, that is, oscillated by supplying an AC signal including a high-frequency component and a low-frequency component, that is, an AC current having a double period, to the drive coil 122.

Further, the actuator 100C has an optical system for optically detecting the swing position, ie, the tilt position, of the movable plate 106. This optical system includes a movable plate 10
6, a light source 174 that emits the light beam A toward the reflection mirror 172, and a two-dimensional detector 178 for detecting the light beam A ′ reflected by the reflection mirror 172. ing. The reflection mirror 172 is
Preferably, it is provided at the center of the movable plate 106.
The light source 174 is, for example, a semiconductor laser or an LED. The two-dimensional detector 178 includes, for example, a two-dimensional PSD,
It is an image sensor such as a CCD.

The light beam A emitted from the light source 174 is
The light is irradiated on a reflection mirror 172 provided on the movable plate 106. The light beam A ′ reflected by the reflection mirror 172 is applied to the two-dimensional detector 178, and forms a light spot on the light receiving surface. The position of the light spot formed on the light receiving surface of the two-dimensional detector 178 changes two-dimensionally according to the two-dimensional swing of the movable plate 106. That is, the two-dimensional detector 1
The position of the light spot 78 on the light receiving surface reflects the two-dimensional swing position of the movable plate 106, that is, the swing position around the first axis and the swing position around the second axis.

Therefore, by examining the position of the light spot on the light receiving surface of the two-dimensional detector 178, the two-dimensional swing position of the movable plate 106 can be known. Alternatively, the two-dimensional swing position of the movable plate 106 can be known by checking the size of the light spot formed on the light receiving surface of the two-dimensional detector 178.

Further, as still another method, the optical system includes:
The two-dimensional detector 178 further has an optical lens 176 for narrowing the light beam A emitted from the light source 174 so that the size of the light spot formed on the light receiving surface of the two-dimensional detector 178 is kept constant. The position may be controlled. In this configuration, based on the displacement of the optical lens 176, the movable plate 1
06 can be obtained.

The movable plate 106 has a total reflection mirror on the surface opposite to the surface on which the reflection mirror 172 is formed, and swings relatively fast around one of the first axis and the second axis. And rocked relatively slowly about the other of the first and second axes. The light beam B is applied to the total reflection mirror of the movable plate 106. The light beam B ′ reflected by the total reflection mirror of the movable plate 106 is two-dimensionally scanned according to the two-dimensional swing of the movable plate 106. Such a two-dimensionally scanned light beam B ′ is projected on a projection surface to form an image.

FIG. 6 shows a state where the light beam B ′ reflected by the total reflection mirror 182 is projected as it is. Here, it is assumed that the light beam B ′ is perpendicularly incident on the projection surface at the stationary position of the total reflection mirror 182, and that the positive and negative swing angles around the two swing axes are respectively equal. In such a setting, the distance between the total reflection mirror and the projection plane increases as the distance from the vertical incidence point, that is, the center, increases, so that the projection range 184 has a square shape with each side curved inward.

Therefore, in the image formation using the actuator of the present embodiment, preferably, as shown in FIG. 7, a curved quadrangular projection range 184 is formed between the total reflection mirror 182 and the projection surface. Correction optical system 186 composed of a free-form surface lens or the like for correcting the projection range 188
It may be added.

The actuator 100C of this embodiment is
It has only one drive coil 122 and the drive coil 12
2 is provided on the movable inner frame 104, so that the movable plate 1
06 is not provided with a driving coil,
Design and manufacturing are easy. Further, it is possible to easily secure a place on the movable plate 106 where the speed detecting element, that is, the reflection mirror 172 is arranged. Further, it is possible to further greatly reduce the size and weight of the movable plate 106, and it is possible to provide an actuator corresponding to scanning at higher speed.

Fourth Embodiment Next, an actuator according to a fourth embodiment will be described with reference to FIG. In FIG. 8, substantially the same members as those of the actuator of the first embodiment are denoted by the same reference numerals, and in the following description, the detailed description is omitted to avoid duplication of the description.

As shown in FIG. 8, the actuator 100D according to the second embodiment includes a fixed outer frame 102 fixedly supported, a movable inner frame 104 located inside the fixed outer frame 102, Movable plate 1 located inside inner frame 104
06, a pair of first torsion bars 112 and 114 connecting the fixed outer frame 102 and the movable inner frame 104, and a pair of second torsion bars 116 and 118 connecting the movable inner frame 104 and the movable plate 106. Having a leaf spring structure.

The movable inner frame 104 is swingably supported with respect to the fixed outer frame 102 by a pair of first torsion bars 112 and 114, and the movable plate 106 is a pair of second torsion bars 116 and 118. Accordingly, the movable inner frame 104 is swingably supported by the movable inner frame 104. Therefore, the movable plate 106
May swing with the movable inner frame 104 about a first axis extending along the pair of first torsion bars 112, 114 with respect to the fixed outer frame 102, and may include a pair of second It may swing alone about a second axis extending along the torsion bars 116,118.

The actuator 100D further includes a pair of first permanent magnets 132, 134 for applying a static magnetic field parallel to the stationary movable plate 106 and extending along the second axis;
A pair of second permanent magnets 142, 144 for providing a static magnetic field parallel to the stationary axis and extending along the first axis
And a drive coil 122 circling the periphery of the movable plate 106
And the first Hall element 15 provided in the movable inner frame 104.
2 and the second Hall element 15 provided on the movable plate 106.
4 is provided.

The pair of first permanent magnets 132, 134
Preferably, they are coupled to yokes 136, 138, respectively. Similarly, a pair of second permanent magnets 142, 144
Are preferably coupled to yokes 146, 148, respectively.

One end of the drive coil 122 is electrically connected to an electrode pad 124 provided on the fixed outer frame 102, and the other end of the drive coil 122 is also provided on the fixed outer frame 102. Is electrically connected to another electrode pad 126. The alternating current including the high frequency component and the low frequency component described in detail in the first embodiment is supplied to the drive coil 122 via the pair of electrode pads 124 and 126.

The movable plate 106 passes through the pair of second torsion bars 116 and 118 due to the Lorentz force generated by the interaction between the current flowing through the drive coil 122 and the magnetic field generated by the second permanent magnets 142 and 144. Around one axis, the second torsion bars 116, 11
8 at a frequency corresponding to the resonance frequency fr2. Further, the movable plate 106 is induced by a minute vibration due to the Lorentz force generated by the interaction between the current flowing through the drive coil 122 and the magnetic field generated by the first permanent magnets 132 and 134, and the movable plate 106 is caused by this vibration. Due to the resonance, the movable inner frame 104 is swung around a first axis passing through the pair of first torsion bars 112, 114 at a frequency corresponding to the resonance frequency fr1 of the first torsion bars 112, 114. You.

As a result, the movable plate 106 is swung about the first axis together with the movable inner frame 104 at a frequency determined by the resonance frequency of the first torsion bars 112 and 114, and At a frequency determined by the resonance frequency of the torsion bars 116, 118, it is oscillated alone about the second axis.

The first Hall element 152 is mounted on the movable inner frame 10.
4 and is preferably located far from the first axis. The second Hall element 154 is located on the movable plate 106, and is preferably located far from the second axis.

The first Hall element 152 cooperates with the magnetic field generated by the pair of first permanent magnets 132 and 134 to correspond to the swinging position of the movable plate 106 around the first axis, that is, the tilting position. Generate a signal. Further, the second Hall element 154 includes a pair of second permanent magnets 142, 144.
In cooperation with the magnetic field generated by the movable plate 106, a signal corresponding to a swing position, that is, a tilt position of the movable plate 106 around the second axis is generated. In FIG. 8, the wiring related to the Hall element is not shown.

The actuator 100D of the present embodiment is
Since it has only one drive coil 122 provided on the movable plate 106 as a coil element for driving, design and manufacture can be easily performed.

Although some embodiments have been described in detail with reference to the drawings, the present invention is not limited to the above-described embodiments, but may be performed within the scope of the invention. Including all implementations.

In the above-described embodiment, an example using a Hall element or a speed detection coil has been described as a method for detecting the swing of the movable plate. However, the method of detecting the swing is not limited to these. For example, a capacitive sensor may be used in place of the Hall element or the speed detection coil, or a combination thereof.

Therefore, the following can be said about the actuator of the present invention.

1. A fixed outer frame fixedly supported, a movable inner frame positioned inside the fixed outer frame, a movable plate positioned inside the movable inner frame, and a first torsion connecting the fixed outer frame and the movable inner frame. A first torsion bar for swingably supporting the movable inner frame around the first axis with respect to the fixed outer frame, and a second torsion bar for connecting the movable inner frame and the movable plate. A second torsion bar for supporting the movable plate with respect to the movable inner frame so as to be swingable around a second axis; a drive coil provided on one of the movable inner frame and the movable plate; And a magnetic field generating means for applying a static magnetic field to the actuator, wherein the first axis and the second axis are non-parallel to each other, and the first torsion bar and the second torsion bar have different resonance frequencies. This actuator has a high frequency component and a low frequency component By alternating current having a double period is supplied to the driving coil including a movable plate is swung at a different frequency to the second axis around the around the first axis.

2. In the actuator of the first aspect, the resonance frequency of the first torsion bar is higher than the resonance frequency of the second torsion bar.

3. In the actuator according to the first aspect, the resonance frequency of the first torsion bar is lower than the resonance frequency of the second torsion bar.

4. In the actuator according to the first aspect, the drive coil is provided on the movable inner frame.

5. In the actuator of the first aspect, the drive coil is provided on the movable plate.

6. 2. The actuator according to claim 1, further comprising a rocking detecting means for detecting a rocking position and a rocking speed of the movable plate, wherein some components of the rocking detecting means are provided on the movable plate. .

7. 2. The actuator according to claim 1, further comprising a swing detecting means for detecting a swing position and a swing speed of the movable plate, wherein a part of the swing detecting means is provided on the movable inner frame. I have.

8. A fixed outer frame fixedly supported, a movable inner frame positioned inside the fixed outer frame, a movable plate positioned inside the movable inner frame, and a first torsion connecting the fixed outer frame and the movable inner frame. A first torsion bar for swingably supporting the movable inner frame around the first axis with respect to the fixed outer frame, and a second torsion bar for connecting the movable inner frame and the movable plate. A second torsion bar for supporting the movable plate with respect to the movable inner frame so as to be swingable around a second axis; a drive coil provided on one of the movable inner frame and the movable plate; And a magnetic field generating means for applying a static magnetic field to the actuator, wherein the first axis and the second axis are non-parallel to each other, and the first torsion bar and the second torsion bar have different resonance frequencies. This is a driving method for driving the actuator Method, by supplying an alternating current having a double cycle including a high frequency and low frequency components to the driving coil, to swing at a frequency different from the second axis around the around the first axis of the movable plate.

9. In the driving method according to the eighth aspect, the low frequency component of the alternating current has a frequency equal to one of the resonance frequency of the first torsion bar and the resonance frequency of the second torsion bar, and the high frequency component of the alternating current is It has a frequency equal to the other of the resonance frequency of one torsion bar and the resonance frequency of the second torsion bar.

10. In the driving method according to the eighth aspect, the AC current is an AC signal in which a low-frequency component and a high-frequency component are superimposed.

11. In the driving method according to the eighth aspect, in the alternating current, the envelope connecting the peaks of the high-frequency component is a low-frequency component.

12. In the driving method according to the eleventh aspect, the low frequency component is a sine wave.

13. In the driving method according to the eleventh aspect, the low-frequency component is a rectangular wave.

[0088]

According to the present invention, since only one drive coil is provided on one of the movable inner frame and the movable plate, design and manufacture are easy, and design freedom is improved. A high degree actuator is provided. Further, in this actuator, by arranging the drive coil in the movable inner frame, it is possible to further reduce the size and weight of the movable plate, and thereby, it is possible to cope with higher-speed scanning.

[Brief description of the drawings]

FIG. 1 is a plan view of an actuator according to a first embodiment of the present invention.

FIG. 2 shows an example of a drive signal suitable for driving the actuator shown in FIG.

FIG. 3 shows another drive signal suitable for driving the actuator shown in FIG.

FIG. 4 is a plan view of an actuator according to a second embodiment of the present invention.

FIG. 5 is a perspective view of an actuator according to a third embodiment of the present invention.

FIG. 6 shows a projection range formed by directly projecting a light beam by scanning of the actuator shown in FIG.

FIG. 7 shows a projection range formed by projecting a light beam through a correction optical system by scanning of the actuator shown in FIG. 5;

FIG. 8 is a plan view of an actuator according to a fourth embodiment of the present invention.

FIG. 9 is a plan view of an actuator according to a conventional example.

10 is a cross-sectional view of the actuator of FIG. 9 taken along line BB.

11 is a cross-sectional view of the actuator of FIG. 9 taken along line CC.

FIG. 12 shows a high-frequency signal for high-speed oscillation supplied to the actuator of FIG. 9;

FIG. 13 shows a low-frequency signal for low-speed oscillation supplied to the actuator of FIG. 9;

[Explanation of symbols]

 100A actuator 102 fixed outer frame 104 movable inner frame 106 movable plate 112, 114 first torsion bar 116, 118 second torsion bar 122 drive coil 132, 134 first permanent magnet 142, 144 second permanent magnet

Continuation of the front page (72) Inventor Masahiro Katahira 2-43-2 Hatagaya, Shibuya-ku, Tokyo F-term in Olympus Optical Industry Co., Ltd. (reference) 2H045 AB13 AB16 AB23 AB38 AB73 BA12

Claims (2)

[Claims] 1. A fixed outer frame fixedly supported, a movable inner frame located inside the fixed outer frame, a movable plate located inside the movable inner frame, and a fixed outer frame and a movable inner frame connected to each other. A first torsion bar for supporting the movable inner frame with respect to the fixed outer frame so as to be swingable around a first axis; and a second torsion bar for connecting the movable inner frame and the movable plate. A torsion bar for supporting the movable plate with respect to the movable inner frame so as to be swingable about a second axis; and a drive provided on one of the movable inner frame and the movable plate. An actuator comprising: a coil; and a magnetic field generating means for applying a static magnetic field to the drive coil, wherein the first axis and the second axis are non-parallel to each other, and the first torsion bar and the second torsion bar Are actuators having different resonance frequencies. 2. A fixed outer frame fixedly supported, a movable inner frame positioned inside the fixed outer frame, a movable plate positioned inside the movable inner frame, and a fixed outer frame and a movable inner frame connected to each other. A first torsion bar for supporting the movable inner frame with respect to the fixed outer frame so as to swing about a first axis, and a second torsion bar for connecting the movable inner frame and the movable plate. A torsion bar for supporting the movable plate with respect to the movable inner frame so as to be swingable about a second axis, and a drive provided on one of the movable inner frame and the movable plate. A coil, and a magnetic field generating means for applying a static magnetic field to the drive coil,
The first axis and the second axis are non-parallel to each other, the first torsion bar and the second torsion bar are a driving method of an actuator having different resonance frequencies, and a high-frequency component and a low-frequency component are generated. A driving method for supplying an alternating current including the driving current to a driving coil.