JP2000081589A - Light deflector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light deflector permitting to detect positional information of a movable plate with higher accuracy and sensitivity. SOLUTION: This light deflector possesses a support 103, a movable plate 101 with a mirror 106 formed at least on one face for reflecting light from a light source, and an elastic member 102 for coupling this movable plate 101 to the support 103 and holding the movable plate 101 to be able to deflect. Further, the light deflector is provided with a driving coil 104 formed at least on one surface of the movable plate 101, a permanent magnet 107 generating a magnetic field in the direction almost parallel to the surface of the movable plate 101, and a hall element 108 which is arranged on the movable plate 101 and detects a deflection angle of deflection movement of the movable plate 101 when the elastic member 102 is elastically deformed by the interaction between current applied to the driving coil 104 and the magnetic field of the permanent magnet 107.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical deflector that reflects light from a light source and scans the reflected light.

[0002]

2. Description of the Related Art Japanese Patent Laying-Open No. 64-2015 discloses an example of a conventional optical deflector, and FIGS. 21A and 21B show the configuration of the optical deflector disclosed in this publication. Is shown. FIG. 21A is a schematic diagram of this optical deflector, and FIG.
FIG. 1 (b) is a sectional view thereof. 1 is a movable plate having a reflecting means on one plane, 2 is a hinge member having a torsion bar structure formed of a metal flat plate, 3 is a support member fixing both ends of the hinge member 2, 40 is a magnet, 6 is a magnet 40, a first coil fixed to the hinge member 2 at a position facing both magnetic poles, 8 is a second coil fixed to the first coil 6, 9 is the first coil 6 and the second coil The yoke 10, which has a magnetic gap in which the coil 8 is located and forms a closed magnetic circuit, is located near the first coil 6 and the yoke 9
The third coil is fixed to the third coil.

In the optical deflector having such a configuration, the first
When an alternating current is applied to the first coil 6, Lorentz force is generated in the first coil 6 in the thickness direction of the movable plate 1 due to the interaction between the current flowing through the first coil 6 and the magnetic field generated by the magnet 40. By this Lorentz force, the movable plate 1
Rotates about a direction parallel to the plane of the movable plate in the hinge member 2 as a center of rotation.

The second coil 8 which rotates simultaneously with the movable plate 1 interlinks with the magnetic flux generated from the magnet 40, and induced electromotive force proportional to the interlinking speed is generated at both ends of the second coil 8. I do. In addition to the above-described induced electromotive force, the second coil 8 also generates an electromotive force due to a mutual induction effect accompanying a change in the current flowing through the first coil 6. In order to reduce the mutual induction electromotive force, the difference between the second coil 8 and the third coil 10 that generates the mutual induction electromotive force is negatively fed back to the first coil 6. The induced electromotive force generated in the second coil 8 in which the mutual induced electromotive force is reduced as described above becomes a speed signal of the movable plate 1, and the second coil 8 and the third coil 10 determine the deflection angle of the movable plate 1. Is a means for controlling This optical deflector can scan the reflected light by irradiating the rotating movable plate 1 with light such as laser light.

[0005] Also, Japanese Patent Application Laid-Open No. 10-90625 discloses that
Another example of a conventional optical deflector is described.

FIG. 22 shows a plan view of such an optical deflector. A movable plate 21, an elastic member 22, a support 23,
It comprises a driving coil 24, a detecting coil 25, a driving coil electrode pad 26, a detecting coil electrode pad 27, and a permanent magnet 28. Here, the movable plate 21, the elastic member 22, the support 23, the drive coil 24, the detection coil 25, and the like are integrally formed by a semiconductor manufacturing method. The movable plate 21 is mainly made of a Si substrate made of a high-rigidity material, and has a reflecting means having a flat reflecting surface on the back surface of the surface on which the driving coil 24 and the detecting coil 25 exist. The elastic member 22 mainly uses an organic material such as polyimide, and supports the movable plate 21 so as to be movable in the thickness direction of the movable plate 21. The support 23 uses the same substrate as the movable plate 21, and fixes the elastic member 22. The drive coil 24 and the detection coil 25 are mainly made of a metal material such as Al or Cu and are wound a plurality of times inside the movable plate 21 as outwardly as possible.
The two coils have a positional relationship substantially immediately above and immediately below each other, and an insulating layer is formed between the two coils to insulate the two coils from each other. The drive coil electrode pad 26 and the detection coil electrode pad 27 are formed on the support 23, and both ends of both coils pass through the elastic member 22 and extend to the support 23. The permanent magnet 28 is magnetized in the plane direction of the movable plate 21 and in a direction perpendicular to the current direction of the driving coil 24 near the magnet. In order to increase the driving force and the output level of the detection signal, the movable plate 21 and the driving coil 24,
It is provided near the detection coil 25.

In the optical deflector having such a configuration, when an alternating current is applied to the driving coil 24, the driving coil 2
The Lorentz force is generated in the driving coil 24 in the thickness direction of the movable plate 21 due to the interaction between the current flowing through 4 and the magnetic field generated by the permanent magnet 28. Due to this Lorentz force, the movable plate 21 translates in the thickness direction of the movable plate with the boundary between the elastic member 22 and the support 23 as a fixed end, and at the same time, moves in the thickness direction of the movable plate with the magnetization direction of the permanent magnet 28 of the elastic member 22 as the central axis. To rotate. The detection coil 25 that translates and rotates simultaneously with the movable plate 21 interlinks with the magnetic flux generated from the permanent magnet 28, and induced electromotive force proportional to the interlinking speed is generated at both ends of the detection coil 25. The induced electromotive force generated in the detection coil 25 becomes a speed signal of the movable plate 21, and the detection coil 25 serves as a means for controlling the deflection angle of the movable plate 21. The optical deflector can scan the reflected light by irradiating the movable plate 21 that translates and rotates with light such as laser light.

[0008]

However, since the signal of the detecting coil used as the detecting means used in the above-mentioned prior art is a speed signal, the position of the movable plate is not accurately detected. Although the speed signal becomes a position signal when it is integrated, the integrated signal may deviate from the accurate position of the movable plate. In particular, when the frequency of the current applied to the drive coil is low, the signal is very weak, so the integration processing signal is likely to be different from the displacement signal of the movable plate. Further, when the applied current is DC, accurate detection is difficult. Therefore, when the movable plate is used as the positioning means, it is not possible to use a detecting means using a driving coil as in the conventional example.

There is also a means in which a strain gauge such as a piezo element is formed on the elastic member and a signal is detected by bending and torsion of the elastic member. However, the deformation of the elastic member does not always correspond to the displacement of the movable plate.

The present invention has been made in view of such a problem, and an object of the present invention is to enable the position information of a movable plate to be detected more accurately and with higher sensitivity than in the past, and to reduce the position information. An object of the present invention is to provide an optical deflector capable of accurately detecting the position of a movable plate even when driven by a frequency signal or a DC signal.

[0011]

In order to achieve the above object, an optical deflector according to the present invention comprises a movable member having a support and a mirror surface formed at least on one surface for reflecting light from a light source. A plate, an elastic member for connecting the movable plate and the support body, and holding the movable plate so as to be able to deflect; a driving coil formed on at least one surface of the movable plate; Magnetic field generating means for generating a magnetic field in a direction substantially parallel to the plane of the plane, and the movable member when the elastic member is elastically deformed by an interaction between a current applied to the driving coil and a magnetic field of the magnetic field generating means. A Hall element for detecting a deflection angle of the deflection motion of the plate.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. Each of the embodiments of the present invention has a common feature that a Hall element is formed on a movable plate. Therefore, first, the operating principle of the Hall element will be described.

As shown in FIG. 1, a rectangular semiconductor thin plate 5
0 and a magnetic flux density B perpendicular to the current I.
When (Z direction) is applied, the Lorentz force is generated in a direction (Y direction) perpendicular to both directions due to the interaction between the current I and the magnetic flux density B. The electrons generated by the current I receive this Lorentz force, so that the direction (Y
Direction), and an electromotive force _VH is generated in the Y direction. V _H is called the Hall electromotive force and is given by the following equation.

V _H = R _H · I · B / t (1) Here, R _H is called a Hall coefficient, and in the case of an n-type semiconductor,
If the electron density is n, it is given by R _H = −1 / ne, and p
In the case of a type semiconductor, if the hole density is p, R _H = 1 / pe
Given by Here, e is the unit charge of electrons. T is the thickness of the thin plate.

Next, a first embodiment of the present invention will be described. The feature of this embodiment resides in that a Hall element is attached on a movable plate and attached. FIG. 2A is a perspective view of the optical deflector according to the first embodiment of the present invention, and FIG. 2B is an optical deflector along AA ′ in FIG. 2A. FIG. The optical deflector according to the first embodiment includes a support 103, a movable plate 101 having a mirror surface 106 formed on one surface for reflecting light from a light source,
An elastic member 102 for connecting the movable plate 101 and the support body 103 to deflectably hold the movable plate 101, and a driving coil 104 formed on the other surface of the movable plate 101
And a coil wiring 111 of the driving coil 104, a permanent magnet 107 as a magnetic field generating means for generating a magnetic field in a direction substantially parallel to the surface of the movable plate 101, and on the movable plate 101 and inside the drive coil 104. Hall element 10 provided
8 and the hall element wiring 109 of the hall element 108
And an insulating film 110 that covers the driving coil 104. The elastic member 102 has a torsion bar structure. In this embodiment, the permanent magnet 107 and the Hall element 1 are used.
08, except for the hall element wiring 109, are monolithically integrated.

The components of the optical deflector according to the present embodiment will be described. It is desirable that the movable plate 101 and the support 103 are mainly formed of a Si substrate or the like, which is a high-rigidity material. It is desirable to form it from an organic material such as polyimide which can make a large angle. As a material of the driving coil 104, Al, Cu or the like having a low resistivity is desirable. In order to increase the driving force of the movable plate 101 and increase the deflection angle, the number of turns is increased while the resistance of the driving coil 104 is kept low, and the position is as close as possible to the permanent magnet 107, that is, as close to the outer edge of the movable plate 101 as possible. Place in position. If the movable plate 101 is a Si substrate, the surface of the mirror surface 106 may be coated with a polished surface of Si or a thin upper portion of aluminum or gold. Permanent magnet 107
Is a movable plate 10 at a position facing both ends of movement of the movable plate 101.
1 and placed close to each other. The permanent magnet 107 is shown in FIG.
(A) It is magnetized in the Y direction and is arranged such that the movable plate 101 side has different magnetic poles. Although the Hall element 108 is inside the driving coil 104 (inside the winding) on the movable plate in FIG. 2, the Hall element 108 may overlap the driving coil 104 in the thickness direction as long as the Hall element wiring 109 can be formed. Good.

In the optical deflector having the above structure, when a current is applied to the driving coil 104, the driving coil 104
Current flowing in the X direction and Y generated from the permanent magnet 107
Due to the interaction with the magnetic field in the direction, a Lorentz force is generated in the driving coil 104 in the Z direction. Due to this Lorentz force, the movable plate 101 rotates around the X direction of the elastic member 102 as a central axis. The optical deflector of the present embodiment is configured to scan the reflected light by rotating the movable plate 101 by the above method while irradiating the mirror surface 106 of the movable plate 101 with light such as laser light.

FIGS. 3A and 3B show the movable plate 1.
01 indicates a state inclined by θ with respect to the neutral position.
In the figure, only the movable plate, the coil, the Hall element and its wiring are shown, and the elastic members and the like are omitted (FIG. 4A).
9 (a), 10 and 11 (a) to 14 (a). The magnetic flux density of the component in the thickness direction of the Hall element 108 is B · sin θ. At this time, the Hall element 108
When a current is caused to flow between the terminals in the X direction of the Hall element 108, the Hall represented by the following equation (1) is obtained between the terminals in the Y direction of the Hall element 108: V _H = R _H IB Sin θ / t (2) Voltage is generated. Thus, when the same Hall element is used and the applied current and the magnetic flux density are the same, the Hall voltage depends on the tendency angle of the movable plate 101, and thus becomes a signal (position signal) indicating the position of the movable plate 101. As a material of the Hall element 108, InSb, InAs, GaAs, or the like having high carrier mobility is desirable. These Hall elements vary depending on the material and shape of the element,
Generally, even when the applied current is several mA and the magnetic flux density is several hundred G, a Hall voltage of several hundred mV is generated.

On the other hand, the signal from the conventional detection coil is on the order of tens to hundreds of μV when the applied current is at a low frequency. Therefore, in the present embodiment, the detection sensitivity is much higher than in the method according to the conventional example. In addition, since the detection signal is a position signal, more accurate position information of the movable plate is detected than in the related art, and accurate detection is possible even in a static state when DC driving is performed.

3 (a) and 3 (b), it is possible to detect even if the direction of the current applied to the Hall element 108 and the direction of the detection voltage are reversed. However, since the detection sensitivity changes depending on the shape of the Hall element 108, this will be described below.

In FIG. 1, the distance between the applied current terminals of the Hall element is L, the distance between the Hall voltage terminals is W,
Expressing (1) in another form, V _H = μ · V ′ · B · W / L (3) Here, V ′ is a voltage applied to the distance L between the applied current terminals of the Hall element, and μ is the carrier mobility. In order to increase the Hall voltage V _H , it is better to decrease the carrier density (electron density n, hole density p) from equation (1). That is, in order to increase the resistance between the applied current terminals, L>
Although a shape that satisfies the relationship of W is more desirable, the applied voltage V ′ must be increased to increase the applied current I.

On the other hand, in a shape that satisfies the relationship of L <W, if the applied voltage and the carrier mobility are the same according to the equation (3), the Hall voltage becomes larger as W becomes larger than L, but the applied current terminal If the resistance between them is too small, the carrier mobility μ becomes smaller. Therefore, in order to increase the resistance between the applied current terminals in order to increase the detection sensitivity, it is desirable to increase the value of W / L by using a shape satisfying the relationship of L> W. It is necessary to consider the limits and power consumption limits.

An example of a method for manufacturing an optical deflector when the movable plate 101 is a Si substrate will be briefly described below. First, an insulating film serving as a mask for later performing Si etching is formed on one surface of the Si substrate by sputtering, CVD, vacuum evaporation, or the like, and is patterned by photolithography. Next, an organic insulating film 10 is formed on the other surface of the Si substrate.
2 is formed into a film by spin coating, printing, or the like to form a pattern. As shown in FIG. 2B, the organic insulating film 102 is formed not only on the movable plate 101 but also on the support 103, and is further patterned into the shape of the elastic member 152. After that, a metal film as a material of the driving coil 104 is formed by sputtering, CVD, vacuum deposition, plating, printing, or the like, and patterns are formed by photolithography. Next, an insulating film 110 is formed thereon to cover the driving coil 104 and the shape of the elastic member 152 is patterned. Then, the Si substrate is etched using the insulating film formed first as a mask.

Up to this point, the manufacturing process up to the formation of the Hall element 108 is performed. By manufacturing the semiconductor device on the same substrate as described above, the movable plate 101, the elastic member 102, the support 103, the drive The coil for use 104 and the mirror surface 106 can be monolithically formed integrally, which facilitates miniaturization and mass production. Finally, the driving coil 104
The Hall element 10 is located at a position on the movable plate 101 inside the
8 as well as the Hall element wiring 109 connected thereto. As described above, the Hall element 108 is made of InSb or InA having a large carrier mobility.
s, GaAs and the like are desirable. In the case of a Hall element having a relatively small carrier mobility, such as Si, the movable plate 101 may be provided with a Hall IC in which a processing circuit for amplifying and / or differentially a Hall voltage signal and a Hall element are integrated.

FIGS. 2A, 2B, 3A,
In FIG. 4B, the Hall element is mounted on the entire inside of the drive coil, but as shown in FIGS.
When the small Hall element 108 is attached to the moving end of No. 1, the entire Hall element 108 becomes closer to the permanent magnet, so that the magnetic flux density B of the Hall element 108 in the thickness direction also increases. Therefore, the Hall voltage V _H generated by equation (2)
And the optical deflector can detect a position signal with higher sensitivity.

As shown in FIGS. 4A and 4B, when the Hall element is attached to the moving end of the movable plate, for example, FIG.
As shown in (a), a mirror surface can be formed on the same surface as the coil and the Hall element. In FIG. 5B, AA ′
FIG. In this case, for example, the following changes may be made in the steps described above. That is, when forming a pattern on the insulating film 102,
The part of the insulating film that forms the mirror surface is removed. Next, when the metal film that is the material of the coil 104 is a material having a high reflectance such as aluminum or gold, the metal film is left on the mirror surface during pattern formation. Further, the insulating film 11
After forming the film 0, a pattern is formed so as to remove a portion covering the mirror surface.

On the other hand, when the coil material is a low-reflectance material such as copper, a pattern for removing the mirror-forming portions of the insulating films 102 and 110 is formed, and then a metal film for forming the mirror-surface is formed. Perform pattern formation. Or,
In any case, the movable plate surface may be used as it is as a mirror surface.

In the configuration shown in FIGS. 5A and 5B, it is sufficient that at least one surface of the movable plate is polished. For example, in the configuration shown in FIGS. There is a feature that an inexpensive material can be used while a polished material needs to be used as a movable plate.

In still another example, FIG.
As shown in (b), the Hall element 108 is arranged at a position where the wiring region of the driving coil 104 near the moving end of the movable plate 101 and the Hall element 108 overlap in the thickness direction of the movable plate 101. As a result, the entire Hall element 108 is closer to the permanent magnet, and the detection sensitivity is increased. Further, the Hall element 108 is used as the driving coil 104
The Hall element 1
In 08, the magnetic flux density from the current flowing through the driving coil 104 becomes a component in a direction substantially parallel to the movable plate 101, and no magnetic flux density is generated in the component in the thickness direction of the Hall element 108. As a result, no Hall voltage is generated due to the interaction with the applied current of the driving coil 104, and the optical deflector can prevent unnecessary signal generation.

Further, when the Hall elements 108 are mounted at the moving ends on both sides of the movable plate 101 and immediately above the driving coil 104 as shown in FIGS. 7A and 7B, the signals are generated from both Hall elements. The detection sensitivity is doubled by adding the Hall voltage.

Further, as shown in FIG. 10, an active amplifier 212 in which a MOS or bipolar transistor having an amplifying function is integrated between both wirings of the Hall element is integrally formed on a movable plate. As a result, the generated Hall voltage is amplified and increased, thereby realizing an optical deflector for generating a highly sensitive position signal.

Although not shown, a Hall IC in which a Hall element and a signal processing circuit are integrated is mounted on the Hall element 108.
By mounting in place of, it is possible to obtain the same effect as the configuration of FIG.

According to the first embodiment described above, by mounting the Hall element on the movable plate, an optical deflector capable of detecting a position signal with higher accuracy and higher sensitivity than before can be realized.

Next, a second embodiment of the present invention will be described. The feature of this embodiment is that the movable plate and the Hall element are monolithically formed integrally. FIG.
(A) and (b) show a second embodiment.

First, as shown in FIGS. 8A and 8B, S
The movable plate 201 made of a semiconductor substrate such as i, InSb, InAs, or GaAs is ion-implanted with a high-concentration impurity having an electron density of about 10 ²⁰ cm ⁻³ to 10 ²² cm ⁻³ as a four-terminal electrode contact. A concentration impurity diffusion layer 211 is formed. After that, the insulating film 210 is interposed on the high-concentration impurity diffusion layer 211, and the Hall element wiring 209 is formed by sputtering, CVD, vacuum evaporation, or the like so as to be in contact with the high-concentration impurity diffusion layer 211 via a contact hole.
To form Thereafter, the formed high concentration impurity diffusion layer 21 is formed.
1. A drive coil 204 is formed above the Hall element wiring 209 via an insulating film 202 also serving as an elastic member.

In FIG. 8B, the driving coil 204 is exposed at the uppermost part, but an insulating film may be formed on the upper part. Thereby, the four-terminal electrode inner region on the movable plate 201 becomes a semiconductor Hall element provided on the movable plate.

As shown in FIG. 8 (a), similarly to the first embodiment, when a current is applied in the X direction, a Hall voltage is generated in the electrodes in the Y direction, and the light deflection that enables the position signal to be detected. Vessel is realized.

As described above, by providing the diffusion layer for the four-terminal electrode contact by ion implantation inside the driving coil on the movable plate, the Hall element can be monolithically formed integrally with the movable plate, thereby reducing the size. It can be mass-produced, and an optical deflector with a significant reduction in manufacturing man-hours and cost can be realized.

Also, as shown in FIGS. 9A and 9B, similarly to FIG. 6 of the first embodiment, the four-terminal electrode contact is arranged so that the Hall element is located immediately below the driving coil 204. A high concentration impurity diffusion layer 210 'is provided. As a result, similarly to the first embodiment, the whole Hall element is closer to the permanent magnet, so that the detection sensitivity is increased, and the magnetic flux density from the current flowing through the driving coil 204 in the Hall element is substantially parallel to the movable plate 201. And does not occur in the thickness direction component. Therefore, no Hall voltage is generated due to interaction with the applied current of the driving coil 204, and an optical deflector that can prevent unnecessary signal generation is realized.

Although FIGS. 9A and 9B show that the Hall element is located immediately below the driving coil 204, the Hall element is located just below the driving coil 204 as in the first embodiment. It may be directly above. Although not shown in the drawing, as in the first embodiment, by mounting a Hall element at the moving end on both sides of the movable plate 201 and at a position directly below or directly above the driving coil 204, double detection sensitivity can be obtained. Can be realized.

Although not shown, the signal processing circuit of the Hall element can be integrally formed on the movable plate to generate a high-sensitivity position signal. A mirror surface is formed on the same plane as the coil and the Hall element. Is also possible.

According to the second embodiment, since the movable plate and the Hall element are monolithically formed integrally, miniaturization and mass production are possible, and the optical deflector is greatly reduced in manufacturing man-hours and cost. Can be realized.

Next, a third embodiment of the present invention will be described. The feature of this embodiment is that a Hall element is monolithically formed integrally, and the Hall element is thinned to obtain a highly sensitive detection means. FIG. 11 (a),
(B) shows a third embodiment.

As shown in FIGS. 11A and 11B, Si, InSb, InAs, G forming the movable plate 301 are formed.
Impurities such as aAs that generate carriers having a polarity opposite to that of the semiconductor substrate are ion-implanted into the movable plate 301 to form an impurity diffusion layer 313. Thereafter, the impurity diffusion layer 31
As in the second embodiment, a high-concentration impurity diffusion layer 311 for Hall element electrode contact is formed by ion-implanting a high-concentration impurity in the third embodiment. Next, an insulating film 310 is interposed therebetween, and the Hall element wiring 3 is contacted with the high-concentration impurity diffusion layer 311 through the contact hole.
09 is formed. After that, the driving coil 3 is placed above the Hall element wiring 309 via the insulating film 302 also serving as an elastic member.
04 is formed.

Thus, the Hall element can be formed monolithically as in the second embodiment. However, in this example, the impurity diffusion layer 313 generates carriers opposite to the movable plate substrate, so that the thickness of the impurity diffusion layer 313 is reduced. t is the thickness of the Hall element. In the second embodiment, the thickness of the Hall element is about several hundred μm because it is the thickness of the substrate. In this embodiment, the thickness is several thousand angstroms, and the equation (1)
Causes the Hall voltage to increase by about three digits.
Therefore, in the third embodiment, an optical deflector that can monolithically form a Hall element that generates a three-digit position signal with high sensitivity is realized.

Next, a modification of the third embodiment will be described. As shown in FIGS. 12A and 12B, the movable plate 3
An insulating film 310 ′ is formed on the entire surface of the movable plate 301 on the substrate 01. Next, a Hall element 314 such as InSb or InAs, which has a high sensitivity for detecting a Hall voltage, is formed on the insulating film 310 'by thinning using a method such as vacuum evaporation or sputtering. Thereafter, similarly to the second embodiment, the Hall element 31
A high-concentration impurity diffusion layer 311 for contacting the Hall element electrode is formed by ion-implanting a high-concentration impurity into the semiconductor substrate 4, and an insulating film 310 ″ is interposed therebetween. Is formed so as to be in contact with.

After that, the driving coil 304 is formed on the Hall element wiring 309 via the insulating film 302 also serving as an elastic member.
To form In the above modification, the thickness of the Hall element can be reduced by the semiconductor (InSb,
(InAs or the like), so that a Hall element that is much thinner than in the second embodiment can be realized. Accordingly, an optical deflector capable of monolithically forming a Hall element for generating a highly sensitive position signal is realized. In this case, the movable plate substrate is not limited to a semiconductor substrate such as Si or GaAs, but may be a metal,
A highly rigid material such as an insulating substrate may be used.

As described above, an optical deflector capable of generating a highly sensitive position signal is realized by forming an insulating film on the movable plate and monolithically forming a Hall element on the insulating film. Here, an embodiment in which a thin-film Hall element is formed by a vacuum deposition or sputtering method has been described. However, the present invention is not limited to this, and a polycrystalline semiconductor (poly-Si or the like) may be formed by CV.
Even when the embodiment (FIG. 13) formed by the method D or the embodiment in which the movable plate is an SOI (Silicon On Insulator) substrate and the upper semiconductor layer is a Hall element (FIG. 14) is employed, the structure shown in FIG. An optical deflector that can generate a highly sensitive position signal can be realized in the same manner as the optical deflector. FIG.
In the embodiments shown in FIGS. 2 and 13, the Si semiconductor is used,
aAs, InSb, and InAs may be used.

As in the first and second embodiments, it is also possible to improve the detection sensitivity and prevent the generation of unnecessary signals by configuring the Hall element so as to be located immediately above or below the driving coil. It is. Further, it is possible to generate a highly sensitive position signal by integrally forming the signal processing circuit of the Hall element on the movable plate.

According to the third embodiment described above, an optical deflector that generates a highly sensitive position signal is realized by integrally forming a thinned Hall element in a monolithic manner.

Although the first to third embodiments have been described with reference to the light deflecting mirror supported by the torsion bar structure, the present embodiment can be applied to a cantilever structure as shown in FIGS. it can. FIG. 15 and FIG.
The operation of No. 6 will be described. FIG. 15 shows an optical deflector formed by attaching a Hall element on a movable plate (corresponding to the first embodiment), and FIG. 16 shows an optical deflector in which the movable plate and the Hall element are integrally formed (No. (Corresponding to two embodiments).

15 and 16, the driving coil 10
When an alternating current is applied to the driving coils 10 and 204, the driving coil 10
4, 204, the current flowing in the Y direction and the permanent magnets 107, 2
07, a Lorentz force is generated in the driving coils 104 and 204 in the Z direction. Due to this Lorentz force, the movable plates 101, 20
Numeral 1 rotates around the Y axis about the boundary between the elastic members 102 and 202 and the support.

When the movable plates 101 and 201 are inclined by an angle θ, the magnetic flux density of the Hall element in the thickness direction becomes B · sin θ. Therefore, even in a cantilever structure,
Similarly to the torsion bar structure, when a current is applied between the terminals of the Hall element in the X direction, the Hall voltage represented by V _H = R _H IB Sin θ / t is applied between the terminals of the Hall element in the Y direction. appear. As a result, the Hall voltage depends on the deflection angle of the movable plate when the same Hall element is used and the applied current and the magnetic flux density are the same.
Signal (position signal) indicating the position of the movable plates 101 and 201
Becomes As described above, since the detection signal is a position signal, more accurate position information of the movable plate than before can be detected, and accurate detection can be performed even in a static state when the DC driving is performed. Although not shown, high sensitivity can be realized by forming a thin Hall element under the Hall electrode with a diffusion layer or an insulating film interposed therebetween, and the arrangement of the Hall element and the signal processing circuit can be realized. The same modifications as those of the first to third embodiments can be made with respect to integration and the like.

Next, a fourth embodiment of the present invention will be described. The feature of this embodiment resides in that the cantilever or gimbal structure is driven two-dimensionally to detect a two-dimensional position signal. 17 to 20 show a fourth embodiment.

First, an optical deflector having a cantilever structure will be described. As shown in FIG. 17, permanent magnets 407-1 and 407-2 magnetized in respective directions are arranged such that magnetic flux densities are generated in two directions of the X direction and the Y direction. Further, the Hall elements 408-1 and 408-2 are bonded to the positions of the movable plate 401 near the respective permanent magnets 407-1 and 407-2 and immediately above the driving coil 404, and are connected to the Hall elements 408-1 and 408-2. The element wirings 409-1 and 409-2 are also bonded.

In the optical deflector having the above configuration, when an alternating current is applied to the driving coil 404, the driving coil 4
Due to the interaction between the current flowing in the X direction in the X direction and the magnetic field in the Y direction generated from the permanent magnet 407-1, the driving coil 404 generates a Lorentz force in the Z direction. Further, the Y-direction current flowing through the driving coil 404 and the permanent magnet 40
By interaction with the magnetic field in the X direction generated from 7-2,
The driving coil 404 generates a Lorentz force in the Z direction. Due to these Lorentz forces, the movable plate 401 pivots around the X direction of the elastic member 402 and pivots around the Y axis around the boundary between the elastic member 402 and the support 403.

When the movable plate 401 is tilted by θ due to the rotational movement, the magnetic flux density of the Hall element 408-1 in the thickness direction becomes B · sin θ. On the other hand, movable plate 40
When 1 is inclined by ψ due to the translational motion, the magnetic flux density of the component in the thickness direction of the Hall element 408-2 becomes B · sinψ
Becomes Thereby, each Hall element 408-1, 408-
When a current flows between the terminals in one direction, V _H = R _H IB sin θ / t between the terminals in the other direction is represented by V _H = R _H IB sin / t. Hall voltage is generated. Accordingly, each Hall voltage uses the same Hall element, and when the applied current and the magnetic flux density are the same, it depends on the respective deflection angles of the movable plate 401. Therefore, by detecting the voltage signal of each Hall element, The deflection angle of the movable plate 401 with two degrees of freedom can be detected.
Further, similarly to the first embodiment, the Hall element 408-1,
Since 408-2 is provided near the moving end of the movable plate 401 and immediately above the driving coil 404, the magnetic flux density generated from the current flowing through the driving coil 404 in the Hall elements 408-1 and 408-2. Is substantially parallel to the movable plate 401 and does not occur in the thickness direction. As a result, no Hall voltage is generated due to the interaction with the current flowing through the driving coil 404, and an optical deflector that can prevent unnecessary signal generation can be realized.

Each of the Hall elements 408-1, 408-
2 are provided directly above the driving coil 404, but the Hall element 408-1 is separated from the permanent magnet 407-2 so as to be hardly affected by the magnetic flux density in the X direction generated from the permanent magnet 407-2. It is desirable to arrange them at different positions. Similarly, the Hall element 408-2 also has a permanent magnet 40
It is desirable to arrange at a position away from 7-1.

FIG. 17 shows an optical deflector formed by bonding Hall elements as in the first embodiment.
As shown in FIG. 8, according to the second embodiment, the high-concentration impurity diffusion layers 411-1 and 411-2 are formed by ion implantation and the movable plate and the Hall element are monolithically integrated to form An optical deflector for dimensional position detection can be realized. Although not shown, as in the third embodiment, an optical deflector capable of two-dimensional position detection can be realized by providing a thin Hall element under a hole electrode via a diffusion layer or an insulating film, as in the third embodiment. Can also.

Next, an optical deflector capable of two-dimensional drive and position detection in a gimbal structure will be described. As shown in FIG. 19, permanent magnets 407-1 and 407-2 magnetized so that magnetic flux density is generated in two directions, X direction and Y direction, are arranged. Further, the Hall elements 408-1 and 408 are located near the respective permanent magnets 407-1 and 407-2 and directly above the driving coils 404-1 and 404-2 of the movable plates 401-1 and 401-2. In addition, the Hall element wirings 409-1 and 409-2 are bonded together by being connected thereto. Also, a yoke for connecting the magnetic poles of the two permanent magnets 407-2 on the side not facing the movable plate 401-2 so that the Hall element wiring 409-1 is less likely to receive the magnetic flux density generated from the permanent magnet 407-2. 418 are provided. Although not shown, a yoke may be provided to connect the magnetic poles of the two permanent magnets 407-1 outside the movable plate 401 on the side not facing the movable plate 401-1.

In the optical deflector having the above-described structure, when an alternating current is applied to the driving coils 404-1 and 404-2, an X-direction current flowing through the driving coil 404-1 and the permanent magnet 407-1 are generated. Due to the interaction with the magnetic field in the Y direction, the movable plate 401-
A Lorentz force is generated in the thickness direction of No. 1. The Y-direction current flowing through the driving coil 404-2 and the permanent magnet 40
By interaction with the magnetic field in the X direction generated from 7-2,
Lorentz force is generated in the driving coil 404-2 in the thickness direction of the movable plate 401-2. Due to these Lorentz forces, the movable plate 401-1 rotates around the X direction of the elastic member 402-1 and the movable plate 401-2 rotates around the Y direction of the elastic member 402-2. Exercising.

Here, when the movable plate 401-1 is inclined by θ, the magnetic flux density of the Hall element 408-1 in the semiconductor film thickness direction becomes B · sin θ, and when the movable plate 401-2 is inclined by ψ, The magnetic flux density of the component in the thickness direction of the element 408-2 is B · sinψ. Thereby, the Hall element 408
-1,408-2 When a current between one direction of terminals, respectively, - each of the other inter direction of the terminal _{V H = R H · I ·} B · sinθ / t V H = R H · I B · A Hall voltage represented by sinψ / t is generated. As a result, each Hall voltage depends on the deflection angle of each movable plate when the same Hall element is used and the applied current and the magnetic flux density are the same.
It becomes a signal (position signal) representing the position of each movable plate 401-1 and 401-2. Further, similarly to the first embodiment, the Hall elements 408-1 and 408-2 are connected to the movable plate 401-1,
401-2 near the moving end of the driving coil 401-2.
1, 404-2, the Hall element 4
08-1 and the drive coil 404- in 408-2
The magnetic flux density generated from the current flowing through the first and the 404-2 becomes substantially parallel to the movable plates 401-1 and 401-2, and does not occur in the thickness direction. Thus, no Hall voltage is generated due to interaction with the current flowing through the driving coils 404-1 and 404-2, and the optical deflector can prevent unnecessary signal generation.

FIG. 19 shows an optical deflector formed by bonding Hall elements as in the first embodiment.
As shown in FIG. 0, a two-dimensional structure in which high-concentration impurity diffusion layers 411-1 and 411-2 are formed by ion implantation and a movable plate and a Hall element are monolithically integrated with each other according to the second embodiment. Optical deflectors are also feasible.

Although not shown, similarly to the third embodiment, by forming a thin Hall element under a hole electrode via a diffusion layer or an insulating film, a light deflection capable of detecting a two-dimensional position is formed. Vessels can also be realized. Furthermore, regarding the arrangement of Hall elements and integration of signal processing circuits,
Modifications similar to the third embodiment are possible.

According to the above-described fourth embodiment, the magnetic flux density is generated in two directions using the cantilever or gimbal structure to drive two-dimensionally, so that a two-dimensional position signal can be detected. An optical deflector is obtained.

The specific embodiments described above include inventions having the following configurations.

(1) A support, a movable plate having at least one surface formed with a mirror surface for reflecting light from a light source, and a connection between the movable plate and the support, An elastic member for deflecting the movable plate, a driving coil formed on at least one surface of the movable plate, magnetic field generating means for generating a magnetic field in a direction substantially parallel to the surface of the movable plate, A Hall element for detecting a deflection angle of a deflection motion of the movable plate when the elastic member is elastically deformed by an interaction between a current applied to a coil and a magnetic field of the magnetic field generating means. A light deflector.

In the optical deflector having this configuration, the detection signal becomes a position signal by providing the Hall element, so that the position information of the movable plate can be detected more accurately than in the past. Further, even when driven by a low frequency signal or a DC signal, the position of the movable plate can be accurately detected. Embodiments corresponding to the present invention are the first to fourth embodiments.

(2) The optical deflector according to (1), wherein the Hall element and a signal processing circuit of the Hall element are provided on the movable plate.

In the optical deflector having this configuration, a signal processing circuit having an amplifying function and a differential function is further provided on the movable plate, so that even a small signal from the Hall element can be amplified, or a magnetic field or current can be reduced. Unnecessary signals generated even when no voltage is applied can be removed. Therefore, an optical deflector capable of detecting a position with higher sensitivity can be realized. Embodiments corresponding to the present invention are the first to fourth embodiments.

(3) The optical deflector according to (1) or (2), further comprising a Hall IC in which the Hall element and a signal processing circuit of the Hall element are integrated.

In the optical deflector having this configuration, a Hall element and a signal processing circuit having an amplifying function and a differential function for the Hall element are integrated on a movable plate, so that the Hall element is provided with a signal from the Hall element. It becomes possible to amplify even a small signal, or to remove an unnecessary signal generated even when no magnetic field or current is applied. Therefore, an optical deflector capable of detecting a position with higher sensitivity can be realized. Embodiments corresponding to the present invention are the first to fourth embodiments.

(4) At least one of the Hall elements is provided in the vicinity of a moving end of the movable plate when the movable plate performs a deflecting motion, according to any one of (1) to (3). Light deflector.

In the optical deflector of this configuration, since the Hall element is provided near the moving end of the movable plate when the movable plate deflects, the magnetic flux density received by the Hall element increases, the detection signal also increases, and a highly sensitive position detection is performed. Can be realized. Embodiments corresponding to the present invention are the first to fourth embodiments.

(5) At least one of the Hall elements is provided at a position overlapping with a wiring region of the driving coil in the thickness direction of the movable plate. An optical deflector according to claim 1.

In the optical deflector of this configuration, the Hall element is provided at a position overlapping the wiring region of the driving coil in the thickness direction of the movable plate, so that the magnetic flux density in the Hall element increases and the current of the driving coil causes An optical deflector that prevents unnecessary signal generation due to interaction with a generated magnetic field can be realized. Embodiments corresponding to the present invention are the first to fourth embodiments.

(6) The optical deflector according to any one of (1) to (5), wherein the Hall element is monolithically integrated with the movable plate.

In the optical deflector having this structure, the Hall element is monolithically formed on the movable plate, so that the optical deflector can be miniaturized and mass-produced. Embodiments corresponding to the present invention are the second to fourth embodiments.

(7) The movable plate is a semiconductor, a four-terminal electrode is provided on the movable plate, and a movable plate region surrounded by the four-terminal electrode is a hall element. An optical deflector according to the item (1).

In the optical deflector having this configuration, the four terminal electrodes are provided on the movable plate, so that the movable plate region surrounded by the four terminal electrodes becomes a Hall element. This makes it possible to monolithically form the Hall element on the movable plate. Embodiments corresponding to the present invention are the second to fourth embodiments.

(8) There is provided a Hall IC in which the Hall element and a signal processing circuit of the Hall element are monolithically formed integrally (6) or (7).
An optical deflector according to item 1.

In the optical deflector having this configuration, a Hall element and a signal processing circuit having an amplifying function and a differential function for the Hall element are monolithically formed on the movable plate. In addition, the signal from the Hall element can be amplified even if it is very small, or unnecessary signals generated even when no magnetic field or current is applied can be removed. Therefore, an optical deflector capable of detecting a position with higher sensitivity can be monolithically integrated. Embodiments corresponding to the present invention are the second to fourth embodiments.

(9) The movable plate is a semiconductor substrate,
A diffusion layer is formed on the movable plate by performing ion implantation to generate carriers having a polarity opposite to that of the movable plate, and the diffusion layer is used as the Hall element (6) to (8). The optical deflector according to any one of the above items.

In the optical deflector having this configuration, a diffusion layer is formed on the movable plate by performing ion implantation so as to generate carriers having a polarity opposite to that of the movable plate, and this diffusion layer is used as a Hall element. Since the Hall element of the diffusion layer is several orders of magnitude thinner than the substrate, the detection signal is increased by several orders of magnitude, and a highly sensitive light deflection element can be realized. Embodiments corresponding to the present invention are the third and fourth embodiments.

(10) An insulating film is formed on the movable plate, and a Hall element is monolithically formed integrally on the insulating film.
An optical deflector according to any one of the above.

In the optical deflector having this structure, the insulating film is formed on the movable plate, and the Hall element is monolithically formed integrally on the insulating film.
A highly sensitive light deflecting element can be realized. Embodiments corresponding to the present invention are the third and fourth embodiments.

(11) The movable plate receives a magnetic field in two directions substantially parallel to the surface of the movable plate to perform a two-dimensional deflection motion, and the Hall element for detecting the deflection angle of the movable plate is provided by the movable plate. The optical deflector according to any one of (1) to (10), wherein at least two light deflectors are provided on the plate.

In the optical deflector having this configuration, when the magnetic flux density is applied in two directions substantially parallel to the surface of the optical deflection mirror having a cantilever or gimbal structure, the movable plate performs a two-dimensional deflection motion. Therefore, by providing at least two Hall elements on the movable plate near the moving end of the movable plate, the position signals of the rotation and translation of the movable plate can be detected. An embodiment corresponding to the present invention is a fourth embodiment.

[0089]

According to the present invention, the position information of the movable plate can be detected more accurately and with higher sensitivity than before, and the position of the movable plate can be detected even when driven by a low frequency signal or a DC signal. It can be detected accurately.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an operation principle of a Hall element.

FIG. 2A is a perspective view of an optical deflector according to a first embodiment of the present invention in which a Hall element is attached on a movable plate and attached thereto, and FIG. 2B is a perspective view of A in FIG. It is sectional drawing of an optical deflector along -A '.

FIG. 3 is a diagram for explaining the operation of the optical deflector shown in FIG. 2;

FIG. 4 is a view showing a modification in which a small Hall element is attached to a moving end of a movable plate.

FIG. 5 is a diagram showing an example in which a mirror element is formed on the same surface as a coil and a Hall element by attaching the Hall element to a moving end of a movable plate.

FIG. 6 is a diagram showing a modification in which a Hall element is arranged at a position near a moving end of a movable plate in a thickness direction of the movable plate with a wiring region of a driving coil.

FIG. 7 is a view showing a modified example in which a Hall element is attached to both ends of movement of a movable plate and directly above a driving coil.

FIG. 8A is a three-dimensional view of a main part of an optical deflector according to a second embodiment of the present invention in which a movable plate and a Hall element are monolithically integrated, and FIG. A-
It is sectional drawing of the optical deflector along A '.

FIG. 9 is a view showing a modification in which a diffusion layer for four-terminal electrode contact is provided such that the Hall element is located immediately below the driving coil.

FIG. 10 is a diagram showing a modification in which a function for amplifying a Hall voltage is added.

FIG. 11A is a perspective view of a main part of an optical deflector according to a third embodiment of the present invention in which a Hall element is monolithically formed integrally, and the element is thinned to realize a highly sensitive detection means. It is a figure, (b) is sectional drawing of the optical deflector along AA 'in (a).

FIG. 12 is a view showing a modification in which an insulating film is formed on the entire surface of a movable plate, and a thin-film Hall element is formed therein.

FIG. 13 shows a polycrystalline semiconductor made of C as a thin-film Hall element.
It is a figure for explaining the modification formed by the VD method.

FIG. 14 is a view showing a modification in which a movable plate is an SOI substrate and an upper semiconductor layer is a Hall element.

FIG. 15 is a view showing a modified example in which the light deflecting mirror section has a cantilever structure and is formed by attaching a Hall element on a movable plate.

FIG. 16 is a view showing a modification in which the light deflection mirror section has a cantilever structure, and the movable plate and the Hall element are integrally formed.

FIG. 17 is a view for explaining an optical deflector having a cantilever structure formed by bonding Hall elements in the fourth embodiment of the present invention.

FIG. 18 is a view showing an optical deflector having a cantilever structure in which a diffusion layer is formed by ion implantation and a movable plate and a Hall element are monolithically integrated.

FIG. 19 is a diagram for explaining an optical deflector having a gimbal structure formed by bonding Hall elements.

FIG. 20 is a diagram showing an optical deflector having a gimbal structure in which a diffusion element is formed monolithically by forming a diffusion layer by ion implantation.

FIG. 21 is a diagram illustrating a first configuration example of a conventional optical deflector.

FIG. 22 is a diagram illustrating a second configuration example of a conventional optical deflector.

[Explanation of symbols]

 101: movable plate, 102: elastic member, 103: support, 104: driving coil, 106: mirror surface, 107: permanent magnet, 108: hall element, 109: hall element wiring.

Claims (1)

[Claims] A movable plate having at least one surface formed with a mirror surface for reflecting light from a light source; connecting the movable plate and the support with each other; An elastic member deflectably held; a driving coil formed on at least one surface of the movable plate; magnetic field generating means for generating a magnetic field in a direction substantially parallel to the surface of the movable plate; A Hall element for detecting a deflection angle of a deflection motion of the movable plate when the elastic member is elastically deformed by an interaction between the current applied to the magnetic field and the magnetic field of the magnetic field generating means. Characteristic optical deflector.