JP2001235702A - Actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an actuator having both high impact resistance and sufficient rigidity for obtaining desired characteristics. SOLUTION: The actuator is equipped with a moving plate 102, a pair of torsion springs 104 extended from both sides of the movable plate 102 and a supporting part 106 for supporting the movable plate 102 through the torsion springs 104. The movable plate 102, torsion springs 104 and supporting part 106 are manufactured by the semiconductor manufacturing technology by using a SOI substrate 110 as a start wafer. The torsion spring 104 is mainly composed of a barrier layer (silicon layer) 116 and a polyimide layer 140. The silicon layer 116 has high rigidity and is a main member which determines the elastic modulus of the torsion spring 104. The polyimide layer 140 has high impact resistance. The polyimide layer 140 covers a moving part 102, the torsion springs 104 and the supporting part 106 except the part of a driving electrode 126.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an actuator.

[0002]

2. Description of the Related Art Actuators are used, for example, for deflecting laser light. There are several driving principles.For example, when a current is applied to an electrostatic actuator that uses Coulomb force or a movable coil placed in a magnetic field, the interaction between the current and the magnetic field causes a force based on Fleming's left-hand rule. There is an electromagnetic drive type actuator using the fact that a voltage is generated in a movable coil, and a piezoelectric drive type actuator using a piezoelectric material whose length changes when a voltage is applied to the material.

Japanese Patent Application Laid-Open No. 7-175005 discloses an electromagnetically driven actuator. This actuator includes a flat movable plate manufactured by processing a silicon substrate, a pair of torsion bars for swingably supporting the movable plate, and a frame-shaped support portion for supporting the torsion bar. . A planar coil for generating a magnetic field when energized is provided at a peripheral portion of an upper surface of the movable plate, and a total reflection mirror is provided at a central portion of the upper surface surrounded by the planar coil. The support is provided with permanent magnets for interacting with the magnetic field generated by the planar coil.

[0004] Both ends of the planar coil are electrically connected to electrode terminals provided on a support portion via coil wiring extending over the torsion bar. The planar coil, the coil wiring, and the electrode terminals are simultaneously formed on the silicon substrate by electroforming. This electromagnetic actuator can be made extremely thinner and smaller than conventional ones.

Japanese Patent Application Laid-Open No. 8-186975 discloses an actuator in which high-concentration boron is diffused into a silicon torsion bar supporting a movable plate to make it conductive, and this is used as a coil wiring.

Japanese Patent Application Laid-Open No. Hei 10-123449 discloses an actuator in which a torsion bar is formed of a polyimide layer and a coil wiring passes through the inside thereof.

[0007]

SUMMARY OF THE INVENTION Japanese Patent Application Laid-Open No. 7-17500
Both the actuators of No. 5 and JP-A-8-186975 have the disadvantage that the torsion bar is made of silicon, so that they have low impact resistance and are therefore easily damaged.

The actuator disclosed in JP-A-10-123449 has high impact resistance because the torsion bar is made of a polyimide layer. However, the torsion bar made of a polyimide layer tends to have insufficient rigidity as compared with the torsion bar made of silicon.

To drive the movable plate at a high vibration frequency,
The torsion bar is required to have high rigidity. The actuator disclosed in Japanese Patent Application Laid-Open No. 10-123449 is
Since the torsion bar is made of polyimide, the rigidity tends to be insufficient, so that it may not be possible to realize desired characteristics, that is, sufficient rigidity corresponding to driving of the movable plate at a high vibration frequency.

It is an object of the present invention to provide an actuator having sufficient rigidity to obtain desired characteristics and high impact resistance.

[0011]

An actuator according to the present invention includes a movable plate, an elastic member extending from the movable plate, and a supporting portion for supporting the movable plate via the elastic member, wherein the elastic member has high rigidity. Including the material and the high impact resistant elastic material, the high rigidity elastic material is the main material that determines the elastic modulus of the entire elastic member, and thus the elastic member has both high rigidity and high impact resistance .

[0012] In one example of the actuator, an elastic material having high impact resistance covers the elastic material having high rigidity.

In another example, the actuator is:
It further comprises a wiring passing through the inside of the elastic member, wherein the wiring is
In the cross section of the elastic member perpendicular to the straight line connecting the movable plate and the support portion, the elastic member is disposed at or near a position where the generated strain is least.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the actuator 1
00 is a movable plate 102 and a pair of elastic members symmetrically extending from both sides of the movable plate 102, for example, a torsion spring 104.
And a supporting portion 106 for supporting the movable plate 102 via the torsion spring 104, and a pair of permanent magnets 108 positioned at both sides of the movable plate 102 in parallel with the axis of the torsion spring 104. I have.

The actuator 100 is secured by a means (not shown) for securing a gap in which the movable plate 102 can vibrate around the torsion spring 104, and the supporting portion 106 retains the actuator.

As shown in FIG. 2, the movable plate 102
It has a drive coil 122 that goes around inside. Although the illustrated drive coil 122 makes two turns, the number of turns is not limited to this, and another number of turns may be used. One end of the drive coil 122 communicates with a spring wire 124 extending through one torsion spring 104, and the spring wire 124 is electrically connected to a drive electrode 126 located on the support 106.

The other end of the drive coil 122 is connected to a jump line pad 128a. Jump line pad 128a
Communicates with the jump line pad 128b via a jump line 132 extending across the drive coil 122. The jump line pad 128b communicates with a spring line 124 extending through the other torsion spring 104, and the spring line 124 is electrically connected to a drive electrode 126 located on the support 106.

The spring line 124 passes through the center where the distortion is smallest with respect to the width q of the torsion spring 104 for the purpose of improving durability and reliability.

As shown in FIGS. 3 and 4 which are cross-sectional views taken along lines AA 'and BB' in FIG. 2, the movable plate 102, the torsion spring 104, and the support 106 are formed of a substrate layer (silicon layer). Layer) 112, a buried silicon oxide film 114, and an active layer (silicon layer) 116 are sequentially stacked.
nsulator) is manufactured by a semiconductor manufacturing technique using the substrate 110 as a start wafer. Therefore, it is manufactured with very high positional accuracy. As shown in FIG. 1, the permanent magnet 10 is placed on the support 106 of the structure thus manufactured.
8 is fixed with an adhesive or the like.

As shown in FIGS. 3 and 4, the drive coil 122, the spring wire 124, the drive electrode 126, and the jump line pads 128a (not shown) and 128b are made of, for example, an aluminum layer and function as an insulating layer. Silicon oxide film 12
0 through the active layer (silicon layer) 1 of the SOI substrate 110
16 is formed. These are the insulating films 13
Covered by 0 and protected from the atmosphere.

The jump line 132 is formed on the insulating film 130. The jump line 132 is covered with an insulating film 134 and protected from the atmosphere. The insulating film 130 and the insulating film 134 are formed of, for example, a silicon oxide film, a silicon nitride film, or the like.

In a portion corresponding to the torsion spring 104, a polyimide layer 140 is formed on the insulating film 130. As shown in FIG. 2, the polyimide layer 140 includes a portion excluding the drive electrode 126 of the support portion 106 and the movable portion 10.
2 is covered.

As can be seen from FIG.
Are mainly the active layer (silicon layer) 11 of the SOI substrate 110
6 and a polyimide layer 140. The torsion spring 104 includes a spring wire 124, a silicon oxide film 120, and an insulating film 130 in addition to the above.

Although the silicon layer 116 has low impact resistance,
The rigidity is high, and mainly determines the elastic modulus of the torsion spring 104. The polyimide layer 140 has low rigidity but high impact resistance. As described above, since the torsion spring 104 is mainly composed of the silicon layer 116 having high rigidity and the polyimide layer 140 having high impact resistance, it has high rigidity and high impact resistance.

In FIG. 4, the thickness t1 of the polyimide layer 140 is preferably at least 8 μm in order to obtain sufficient impact resistance.

2 to 4, for example, the insulating film 13
It is preferable that 0 has a compressive stress and the polyimide layer 140 has a tensile stress. This is because the deformation of the torsion spring 104 due to the compressive stress of the insulating film 130 is caused by the polyimide layer 14.
Since it is relaxed and reduced by a tensile stress of 0, it is preferable to obtain desired driving characteristics. Also, in the movable plate 102, for the same reason as in the torsion spring 104, deformation due to stress is reduced and reduced, so that the shape of the reflection surface is not easily deformed.

The factor that determines the resonance frequency for driving the movable plate 102 is dominated by the thickness of the active layer 116. In the manufacture of the actuator 100, the thickness of the wafer required for reasons such as handling may be larger than the thickness of the silicon layer 116 necessary for forming a torsion spring having desired characteristics. In such a case, when a silicon substrate having a required thickness is used, the rigidity of the torsion spring becomes too high to obtain a desired resonance frequency.
If a substrate is used, the required thickness can be satisfied, but the torsion spring 104 can be thinned to an accurate thickness by semiconductor manufacturing technology, and a desired resonance frequency can be obtained.

As shown in FIG. 3 and FIG.
6 denotes a substrate layer (silicon layer) 112 of the SOI substrate 110, a buried silicon oxide film 114, and an active layer (silicon layer) 1
16, a silicon oxide film 120, a drive electrode 126,
It includes an insulating film 130 and a polyimide layer 140.

As shown in FIG. 3 and FIG.
2 denotes a substrate layer (silicon layer) 112 of the SOI substrate 110, a buried silicon oxide film 114, and an active layer (silicon layer) 1.
16, the silicon oxide film 120, the drive coil 122
And jump line pads 128a (not shown) and 128b
, Insulating film 130, jump line 132, insulating film 13
4 is included. Further, the movable section 102 includes a polyimide layer 140.

The movable section 102 has a reflecting section 118 for reflecting light. The reflection unit 118 is configured by, for example, a polished surface of a substrate layer (silicon layer) 112 of the SOI substrate 110. This is suitable for saving processing time and materials for forming the reflection portion. For reflection of light of a semiconductor laser or the like having a wavelength of about 650 nm, an aluminum film having a higher reflectance than silicon as a material of the substrate layer for light of this wavelength may be formed by, for example, sputtering or vapor deposition. .

1 and 2, when a current is supplied to the drive electrode 126 and a current flows through the drive coil 122, a torsion spring is applied to the movable plate 102 by interaction with a magnetic field generated by the permanent magnet 108. A torque about 104 is generated. If the current is an alternating current, the movable plate 102 reciprocates at a predetermined deflection angle around the torsion spring 104. The light reflected by the reflector 118 shown in FIGS. 3 and 4 is deflected according to the movement of the movable plate 102.

Hereinafter, the manufacturing process of this actuator will be described with reference to FIGS. The cross sections of the respective steps shown in FIGS. 5 and 6 are cross sections cut along the line B′-C in FIG.

Step 1 (FIG. 5A): SO having a substrate layer 112, a buried silicon oxide film 114, and an active layer 116
An I substrate 110 is prepared. Both the surface of the substrate layer 112 and the surface of the active layer 116 are polished and mirror-finished.

FIG. 7 shows the SOI substrate wafer after the step 10 described later is completed. As can be seen from FIG. 7, for example, four actuators 100 are manufactured on one SOI substrate wafer 110. However, the number of actuators manufactured on one SOI substrate wafer 110 is not limited to this. 5 and 6
Will be described for one actuator.

Step 2 (FIG. 5B): A silicon oxide film 136 is formed on the surface of the substrate layer 112 and a silicon oxide film 120 is formed on the surface of the active layer 116 by, for example, an oxidation furnace.

Step 3 (FIG. 5C): The silicon oxide film 120 is removed by etching using a photolithography technique, except for the portion that becomes the movable plate 102, the portion that becomes the torsion spring 104, and the portion that becomes the support portion 106. At the same time, the silicon oxide film 136 is transferred from the portion to be the movable plate 102 to the supporting portion 10.
Except for the portion that becomes 6, it is etched away.

Step 4 (FIG. 5D): Silicon oxide film 120
A film of aluminum is formed, for example, by a sputtering technique, and then patterned by a photolithography technique, so that the drive coil 122, the spring wire 124, and the drive electrode 1 are formed.
26, jump line pads 128a (not shown) and 128b
To form

Step 5 (FIG. 5E): For example, a plasma CVD (Chemical vapor deposit) is formed on the surface of the structure on the side of the active layer.
on) After a silicon oxide film or a silicon nitride film is formed by an apparatus or a sputtering apparatus, the insulating film 130 is formed by patterning the silicon oxide film or the silicon nitride film by photolithography. Alternatively, the insulating film 130 may be formed by forming a polyimide film and patterning the film by a photolithography technique. Alternatively, the insulating film 130 may be formed by depositing polyimide in a state patterned by a printing method.

Step 6 (FIG. 5F): On the insulating film 130,
For example, after a film is formed by using a sputtering apparatus, aluminum is patterned by a photolithography technique to form a jump line 132. After that, a silicon oxide film or a silicon nitride film is formed on the active layer side surface of the structure by, for example, a plasma CVD device or a sputtering device, and then patterned by a photolithography technique to form an insulating film 134. Alternatively, the insulating film 134 may be formed by forming a polyimide film and patterning the film using a photolithography technique. Alternatively, the insulating film 134 may be formed by forming a polyimide film in a state patterned by a printing method.

Step 7 (FIG. 6A): A polyimide film is formed on the surface of the structure on the active layer side, and patterned by photolithography to form a polyimide layer 140. Note that a film may be formed in a state where the polyimide is patterned by a printing method. In addition, jet printing
Patterning may be performed using the system.

Step 8 (FIG. 6 (b)): With respect to the active layer side surface of this structure, a portion to become the movable plate 102 and the torsion spring 1
The part which becomes 04 and the part which becomes the support part 106 are masked with a resist, for example, RIE (Reactive ion etching).
The active layer 116 is etched by the apparatus, and then the resist is removed. By this etching, the movable plate 102
And the active layer portion of the support portion 106 are separated except for the portion of the torsion spring 104.

Step 9 (FIG. 6C): With respect to the surface of the structure on the substrate layer side, the substrate layer 11 is formed from the back surface by the RIE apparatus.
2 is etched. At this time, it is desirable to use RIE having a sufficient etching selectivity between silicon oxide and silicon. Thus, etching can be performed using the silicon oxide film 136 as a mask without patterning the resist. In addition, at the end of the etching of the substrate layer 112, when the overetching is performed to completely remove the substrate layer 112, the buried silicon oxide film 114 is removed.
Therefore, the active layer 116 that should not be etched is not etched. Alternatively, the substrate layer 112 may be etched by crystal anisotropic etching of silicon using an alkaline etchant, for example, an aqueous solution of tetramethylammonium hydroxide. By this etching, the movable plate 102 and the substrate layer portion of the support portion 106 are separated.

Step 10 (FIG. 6D): The silicon oxide film 136 and the buried silicon oxide film 114 on the substrate layer side surface are simultaneously removed by RIE from the substrate layer side surface of this structure. Thus, the movable plate 102, the torsion spring 104, and the support portion 106 are formed, and the movable plate 102 is supported by the support portion 106 via the torsion spring 104.

Step 11 (not shown): This structure is diced and cut from the SOI substrate wafer, and the permanent magnet 1
08 is mounted with, for example, an adhesive.

According to the present embodiment, an actuator having a torsion spring having both high rigidity made of silicon and high impact resistance made of polyimide can be obtained. Thus, an actuator having desired driving characteristics and high impact resistance is provided. The actuator can be easily manufactured by a manufacturing technique of stacking flat layers such as a general semiconductor manufacturing technique or a printed wiring board manufacturing technique.

When the plane layer has an internal stress, the stress can be relaxed / canceled by overlapping the plane layer having a tensile stress and the plane layer having a compressive stress,
By preventing deformation of the elastic member and keeping it in a desired shape, the characteristics of the actuator caused by the elastic member can be made as desired.

In the actuator according to the present embodiment, the flat layer having high impact resistance is the end layer of the elastic member. Therefore, when the elastic member becomes the point of action and an impact force is applied, the flat layer having high impact resistance is applied. Absorbs the impact force, so the impact resistance is high,
Further, since the torsion spring has high rigidity, a high resonance frequency can be realized. Furthermore, since the spring wire is formed inside the torsion spring, the stress applied when the torsion spring is twisted is smaller than that when the spring wire is formed on the surface of the torsion spring. This makes it difficult for the spring wire to break, so that the reliability is high and the life is long.

A first modification of the first embodiment will be described with reference to FIG. FIG. 8 shows a step that follows the step 10 of FIG. A polyimide layer 142 is formed on the active layer 116 of the torsion spring 104 from a surface side of the substrate layer by a printing method or a jet printing system. Subsequently, as in the first embodiment, dicing is performed, and a permanent magnet is mounted to complete the actuator.

In this actuator, when an impact force is applied in the x-direction, the point of action of the force in the x-direction generated due to the mass of the substrate layer 112 of the movable plate 102 is
In the plane perpendicular to the x direction. As a result, the movable plate 1 is placed on the active layer 116 of the torsion spring 104 that is weak in impact resistance.
It is difficult to apply a force in the x direction generated due to the mass of the substrate layer 112 of No. 02. Therefore, an actuator having excellent impact resistance and desired driving characteristics can be obtained.

Further, this actuator has higher impact resistance because the polyimide layers 140 and 142 having high impact resistance are layers at both ends of the torsion spring 104.

A second modification of the first embodiment will be described with reference to FIG. FIG. 9 shows a step that follows the step 10 of FIG. A polyimide layer 144 is formed on the active layer 116 of the torsion spring 104 from a surface side of the substrate layer by a printing method or a jet printing system. The polyimide layer 144 is formed to have a thickness whose surface substantially matches the surface of the substrate layer 112. Subsequently, as in the first embodiment, dicing is performed, and a permanent magnet is mounted to complete the actuator.

As a result, the torsion spring 1 having a weak impact resistance
The active layer 116 of the movable plate 102 corresponds to the substrate layer 11 of the movable plate 102.
The force in the x direction generated due to the mass of the two parts is less likely to be applied than in the first modification. Therefore, the torsion spring 104 has higher impact resistance.

Further, in this actuator, the polyimide layers 140 and 142 having high impact resistance are layers at both ends of the torsion spring 104, and the polyimide layer 144 is thicker than the polyimide layer 142 of the first modified example. Has high impact resistance.

FIGS. 10 to 1 show a third modification of the first embodiment.
2 will be described.

First, the manufacturing process of the actuator of this modification will be described. The manufacturing process is the same as the process up to the process 6 shown in FIG. 5 of the first embodiment up to the middle, and the process after the process 7 is different. Hereinafter, step 6 is omitted, and step 7 and subsequent steps will be described with reference to FIGS.

Step 7 (FIG. 10A): On the active layer side surface, a portion except for the movable plate 102, the torsion spring 104, and the support portion 106 is masked with a resist, for example, RIE (R)
The active layer 116 is etched by an eactive ion etching apparatus, and then the resist is removed. This allows
The movable plate 102 and the active layer portion of the support portion 106 are separated except for the portion of the torsion spring 104.

Step 8 (FIG. 10B): In order to mask the drive electrode 126, the resist 150 is patterned by using the photolithography technique. Resist 15
0 may be formed by a printing method.

Step 9 (FIG. 10C): On the substrate layer side surface, the substrate layer 112 is etched from the back surface by the RIE apparatus. At this time, it is desirable to use RIE having a sufficient etching selectivity between the silicon oxide film and silicon. Thereby, in addition to using the silicon oxide film 136 on the substrate layer side surface as a mask at the time of etching without patterning the resist, in addition to completely removing the substrate layer 112 at the end of etching of the substrate layer 112, When over-etching is performed, the buried silicon oxide film 114 prevents the active layer 116 that should not be etched from being etched.
Alternatively, the substrate layer 112 may be etched by crystal anisotropic etching of silicon using an alkaline etching solution, for example, an aqueous solution of tetramethylammonium hydroxide. By this etching, the movable plate 102 and the substrate layer portion of the support portion 106 are separated.

Step 10 (FIG. 10D): The silicon oxide film and the buried silicon oxide film 114 on the substrate layer side surface are simultaneously etched and removed by RIE from the substrate layer side surface. Thereby, the movable plate 102, the torsion spring 104, and the support portion 1
06 is formed, and the movable plate 102 is supported by the support portion 106 via only the torsion spring 104.

Step 11 (FIG. 11A): For example, copper 152 is formed on the entire actuator by electroless plating. However, the copper 152 is not formed on the drive electrode masked with the resist 150.

Step 12 (FIG. 11B): The resist 150 is removed with, for example, acetone. As a result, FIG.
FIG. 12B shows a cross section taken along the line DD ′ in FIG.
The torsion spring 104 is covered with copper 152 around the torsion spring 104 as shown in FIG.

Step 13 (not shown): The actuator is diced and cut out from the SOI substrate wafer, and a permanent magnet is mounted using, for example, an adhesive.

In this modification, the torsion spring 104 is provided with a metal film such as copper 152 having high impact resistance around the active layer 116 having high rigidity but low impact resistance. An actuator having not only driving characteristics but also impact resistance can be obtained. The member having high impact resistance, that is, copper 152, is made of the member having high rigidity, that is, active layer 1.
When the actuator falls, even if the elastic member, that is, the portion of the torsion spring 104 becomes the point of application of the impact force, when the actuator falls, the member having high impact resistance absorbs the impact force. It is difficult for impact to be transmitted to tall members.

A fourth modification of the first embodiment will be described with reference to FIG. FIG. 13 is a diagram corresponding to a cross section taken along line B′-C in FIG. In this modification, the start wafer of the first embodiment is manufactured by changing the SOI substrate to a silicon wafer having a single silicon layer. Therefore, as shown in FIG. 13, in the present modification, the portion of the torsion spring 104 corresponding to the active layer of the first embodiment is the silicon wafer 156 itself.
As a result, the desired thickness of silicon used for the torsion spring 104 is set to a thickness d of about 0.3 mm, which is a minimum value of a thickness that can be generally processed at a production level by a semiconductor manufacturing apparatus in a wafer state. When the thickness is equal to or larger than the first embodiment, the present modification is more suitable than the first embodiment.

When an impact force is applied in the x direction, the movable plate 102
The point of action of the force in the x-direction generated due to the mass of the silicon portion is located on the plane of the movable plate 102 perpendicular to the x-direction. As a result, a force in the x direction generated due to the mass of the silicon portion of the movable plate 102 is not applied to the silicon portion of the torsion spring 104 that is weak in impact resistance. As a result, the y-direction force generated due to the mass of the silicon portion of the movable plate 102 is not applied to the torsion spring 104. Therefore, an actuator having excellent impact resistance and desired driving characteristics can be obtained.

Also, in this modification, one layer of the wafer is made of SO
Since it is generally inexpensive compared to an I-substrate wafer, it is possible to provide an inexpensive actuator having desired driving characteristics, high impact resistance and high cost.

A fifth modification of the first embodiment will be described with reference to FIG. FIG. 14 is a diagram corresponding to a cross section taken along line B′-C in FIG. In this modification, the start wafer of the first embodiment is manufactured by changing the SOI substrate to a silicon wafer composed of a single silicon layer. Further, as shown in FIG. , The portion of the torsion spring 104 is reduced to a thickness tsi.

The actuator of this modification is manufactured, for example, as follows. In the manufacturing process of the first embodiment, the start wafer is changed from an SOI substrate to a silicon wafer, and steps 1 to 7 are applied. Step 8
In FIG. 6B, a portion to be the movable plate 102, a portion to be the torsion spring 104, and a portion to be the support portion 106 are masked with a resist, and the silicon wafer 156 is removed from the upper surface by RIE. The amount of silicon etching is controlled for time, and etching is performed by tsi. Thereafter, etching is performed using the silicon oxide film 136 on the back surface as a mask, and the movable plate 102 and the support portion 106 are separated except for the torsion spring 104. As a result, the silicon wafer 156 is placed on the portion of the torsion spring 104 by tsi.
Only the thickness remains. Step 10 and subsequent steps are the same.

As a result, an actuator having a configuration according to the first embodiment can be manufactured without using an expensive SOI substrate. However, since the etching rate of the RIE apparatus generally has a variation tolerance within the wafer surface, this modification is suitable when the specification of the thickness of the torsion spring can be satisfied with the etching accuracy of the RIE to be used. Further, the etching of silicon is not limited to RIE, and may be performed by wet etching, for example.

A sixth modification of the first embodiment will be described.

In this modification, in FIGS. 2 to 4, the spring wire 124 is disposed at a position where the distortion is minimized when the torsion spring 104 is twisted, thereby preventing the spring wire 124 from breaking.

2 to 4, the width of the torsion spring 104 is q, the thickness of the polyimide layer 140 is t ₁ , its transverse elastic modulus is G ₁ , the thickness of the active layer 116 is t ₂ , the modulus of transverse elasticity and G _2. Between t ₁ and t ₂ , when the shape of the elastic member is q> 2t ₁ and q> 2t ₂ , k ₁ ≡ (1
/3)−0.21×(2t ₁ / q) × (1− (2t ₁ / q) ⁴ ), k ₂
≡ (1/3) −0.21 × (2t ₂ / q) × (1− (2t ₂ / q) ⁴ )
When t ₁ is determined, t ₁ and t ₂ (G ₂ k ₂ / G ₁ k ₁ ) ^1/3 substantially match, or the shape of the elastic member is q ≦ 2t ₁ and q ≦ 2t ₂
, K ₁ ｋ (１) −0.21 × (q / 2t ₁ ) ×
(1− (q / 2t ₁ ) ⁴ ), k ₂ ≡ (１) −0.21 × (q / 2t
₂ ) × (1− (q / 2t ₂ ) ⁴ ), t ₁ and t ₂ (G ₂ k ₂
/ G ₁ k ₁ ) or the elastic member has a shape of 2
When t ₂ ≦ q ≦ 2t ₁ , k ₁ ≡ (１) −0.21
× (q / 2t ₁ ) × (1- (q / 2t ₁ ) ⁴ ), k ₂ ≡ (1/3) -0.
21 × (2t ₂ / q) when defined as _{× (1- (2t 2 / q} ) 4), t 1 and ^{_{4t 2 3 (G 2 k 2}} / G 1 k 1) and q ^-2 substantially coincide ,... (Equation 1) hold. By doing so, FIG.
In FIG. 4, the spring line 124 is located at a position where the distortion is smallest when the torsion spring 104 is twisted, and the spring line 124 is hard to be broken. The reason is as follows.

Generally, in a torsion spring, when its cross section is rectangular or square (hereinafter simply referred to as a rectangle), the specific torsion angle θ, the long side a of the rectangle, the short side b of the rectangle,
When a ≧ b, between the torsional moment T and the transverse elastic coefficient G determined by the material of the torsion spring, θ = T ÷ (k × a × b ³ × G) (Equation 2) holds. Here, k is a coefficient determined by the value of a / b, and is given by: k = (1/3) −0.21 × (b / a) × (1−b ⁴ / a ⁴ ) (Equation 3) (BR Hopkins "Design Analysis of Sha
fts and Beams. 2nd Ed "(1987). In this case, the torsion axis of the torsion spring is perpendicular to the cross section and passes through the intersection of the long side bisector and the short side bisector (Fig. 15 (A)).

Here, in the torsion spring having the rectangular cross section, the torsion spring is obtained by dividing only the long side of the torsion spring cross section into two equal parts without changing the torsion axis as it is (FIG. 15B). A torsion spring bisecting only the side (Fig. 15
In (C)), since the torsional moment required to rotate θ is T / 2, from Equation 2, θ = (T / 2) ÷ (k × a × b ³ × G) (Equation 2) 4)

In FIGS. 2 to 4, the interface between the polyimide layer 140 and the active layer 116 is a plane including the torsion axis of the torsion spring 104 so that the surface where the torsion spring 104 is twisted has the smallest strain. To achieve this, the polyimide layer 140 and the active layer 116 are formed by q and 2t ₁ and q and 2t ₂
Considering the magnitude of the torsion spring corresponding to the torsion spring shown in FIG. 15 (B) or FIG. 15 (C), Equation 1 may be satisfied. This is because the same torsional moment acts on the polyimide layer 140 and the active layer 116 constituting the torsion spring when the torsional moment acts on the torsional spring of FIGS. 2 to 4. Since the polyimide layer 140 and the active layer 116 constituting the torsion spring are distorted at the same specific twist angle, the bisector of the width q in the interface between the polyimide layer 140 and the active layer 116 in FIGS. Is the torsion axis. Therefore, the interface between the polyimide layer 140 and the active layer 116 in FIG. 2 to FIG. 4 is a plane having the smallest strain in the thickness direction of the torsion spring 104. 2 to 4, since the spring wire 124 is formed at the interface between the polyimide layer 140 and the active layer 116 having the smallest strain, the stress on the spring wire 124 is small,
The durability of the spring wire 124 is improved.

A specific numerical example of this modification is shown below.
2 to 4, the width of the torsion spring 104: q = 10
8 μm, modulus of longitudinal elasticity of active layer (silicon layer) 116: E ₂
= 130 GPa (Esashi, Fujita, Igarashi, Sugiyama "Micromachining and Micromechatronics" Baifukan, 100
(Page (1992)) Poisson's ratio of the active layer (silicon layer): ν = 0.3, therefore, the transverse elastic modulus of silicon: G ₂ = (１) × E ₂ / (ν + 1) =
50 GPa, thickness of active layer (silicon layer) portion of torsion spring 104: t ₂ = 10 μm, transverse elastic coefficient of polyimide:
G ₁ = 2.75 GPa (H. Miyajima, N. Asaoka, M. Arim
a, Y. Minamoto, K. Murakami, K. Tokuda, K. Matsumo
to.Transducers '99 Proceedings p.372 (1999)),
The thickness of the polyimide portion of the torsion spring: t ₁ = 28 μm.

In this case, since q> t ₁ and q> t ₂ , k ₁ ≡ (１) −0.21 × (2t ₁ /
q) × (1- (2t ₁ / q) ⁴ ), k ₂ ≡ (１) −0.21 ×
When (2t ₂ / q) × (1− (2t ₂ / q) ⁴ ), t ₁ and t
₂ (G ₂ k ₂ / G ₁ k ₁ ) ^1/3 should be approximately the same, and if the above value is substituted for t ₂ (G ₂ k ₂ / G ₁ k ₁ ) ^1/3 , 28 μm And this value is equal to t ₁ = 28 μm. of course,
A match is included in a near match.

When it is difficult to form a 28 μm polyimide layer at one time, the film is divided into a plurality of layers, and a plurality of polyimide layers are stacked so as to have a total thickness of 28 μm. You may.

A seventh modification of the first embodiment will be described with reference to FIG. In the drawing, members that are functionally the same as the members of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

The actuator of this modification is manufactured by diverting the semiconductor manufacturing technology described in the first embodiment, and is shown in FIG.
As shown in FIG. 6 (A), one movable plate 102 is supported by a support portion 106 via one torsion spring 104, and the support portion 106 includes a pair of movable members 102 arranged on both sides of the movable plate 102. Is attached to a fixing member 162 that holds the permanent magnet 108 of the first embodiment. The movable plate 102 is twisted and driven by an interaction between a drive coil 122 provided on the movable plate 102 and a pair of permanent magnets 108 disposed on both sides thereof.

FIG. 16B shows a cross section taken along line LL ′ of FIG. 16A, and the insulating film and the like are omitted. In this modification, as shown in FIG. 16B, two spring wires 124 pass through one torsion spring 104. The two spring wires 124 correspond to the torsion spring 10.
When 4 is twisted, it is arranged at the position where the distortion is the smallest. Specifically, the two spring lines 124 are arranged symmetrically with respect to the bisector MM ′ of the width q of the torsion spring 104. Such an arrangement relationship is based on the spring line 124.
Is hardly broken.

Such an arrangement relationship is based on two spring wires 12
The same advantage is provided not only to four but also to three or more spring wires 124. For example, when three spring lines 124 pass through one torsion spring 104, as shown in FIG. 16C, the three spring lines 124 are bisectors to the width q of the torsion spring 104. What is necessary is just to arrange so that it may become line symmetric with respect to MM '.

An eighth modification of the first embodiment will be described with reference to FIG. In the drawing, members that are functionally the same as the members of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

The actuator of this modification is manufactured by diverting the semiconductor manufacturing technology described in the first embodiment, and is shown in FIG.
As shown in FIG. 7 (A), one movable plate 102 is supported by a support portion 106 via one flexible spring 105 which is an elastic member.
The support portion 106 is attached to a fixed member 162 that holds one permanent magnet 108 that is spaced apart from the free end of the movable plate 102. The movable plate 102 is provided with a drive coil 12 provided thereon.
2 and the permanent magnet 108 opposed thereto is driven to bend.

FIG. 17B shows a cross section taken along line LL ′ of FIG. 17A, and the insulating film and the like are omitted. In this modification, as shown in FIG. 17B, two spring wires 124 pass through one flexible spring 105. The two spring wires 124 are arranged on a plane (neutral plane) where distortion is the smallest.

Here, according to the material mechanics (for example, by Nishimura,
"Material mechanics learned by example" Maruzen (1987)), a deflection curve v showing a beam shape when a concentrated load W acts on a free end of a cantilever having a length l is given by: v = (W / 6EI) × (x ³ −3l ² x + 2l ³ ) (0 ≦ x ≦ l). Here, x represents the distance to the fixed end side, with the free end side of the beam being 0. Also, E
Is the longitudinal modulus of elasticity of the beam, and I is the second moment of area of any line in the neutral plane. When calculating the I in rectangular ^{cross-section, I = ab 3/12 (} a: the length of a side perpendicular to the direction deflection of the cantilever, b: the length of the sides parallel to the direction of deflection of the cantilever) is. When v becomes the same for two members at the same W for two different members,
The boundary between the two members is a neutral plane.

Therefore, the longitudinal elasticity of polyimide and silicon
E number₁And E_TwoThen E ₁t₁ ^Three= E_Twot_Two ^ThreeIn
You. Therefore, t₁= T_Two(E_Two/ E₁)^1/3.. (Equation 5) holds, the flexure spring 105 shown in FIG.
The boundary between the polyimide layer 140 and the silicon layer 160 is
It becomes an upright surface, and the spring wire 124 is less likely to break.

For example, from the sixth modification of the first embodiment,
Assuming that E ₂ = 130 GPa and the Poisson's ratio of the polyimide is 0.3, G ₁ = 2.75 G from the sixth modification of the first embodiment.
Pa, E ₁ = 7.15 GPa, silicon thickness t ₂ = 1
In the case of 0 μm, from Equation 5, the polyimide thickness t ₁ = 40 μm
Becomes

Therefore, in the above configuration, since the spring wire 124 is disposed on the surface where the stress is the smallest, the durability of the spring wire 124 is improved.

When it is difficult to form the polyimide film to the above-mentioned thickness in one process, the film may be formed in two or more steps, and the total thickness of the two or more polyimide layers is 26 μm.
m.

A ninth modification of the first embodiment will be described with reference to FIG. In the drawing, members that are functionally the same as the members of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

The actuator according to the present modification has a movable plate 10
In order to detect the position 2, a detection coil 164 provided on the movable plate 102 is provided separately from the drive coil 122. Both ends of the detection coil 164 are connected to a spring line 168 via a jump line 166 extending over the drive coil 122, respectively. The spring line 168 is
The flexible spring 105 extends and is connected to an electrode 170 provided on the support 106.

In this actuator, the detection coil 16
4 and the permanent magnet 108 generate an induced electromotive force. As a result, an electric signal reflecting the position of the movable plate 102 flows to the detection coil 164, and this electric signal is
0, and the position of the movable plate 102 can be determined based on the extracted electric signal.

In the above-described embodiments and their modifications, the elastic member, that is, the torsion spring 104 or the flexible spring 1 is used.
The spring wire extending through 05 is a wire for supplying a current to the drive coil, but is not limited to this. For example, as in the present modification, the spring wire is a wiring for flowing an electric signal flowing through the detection coil 164 provided on the movable plate 102 for detecting the position of the movable plate 102 from the movable plate 102 to the support portion 106. There may be.

The detection coil of the present modification is applied to a cantilevered flexible spring type actuator. However, a cantilevered spring type actuator shown in FIG. 16 and a double-ended torsion type shown in FIG. 1 are used. It may be applied to a spring type actuator.

Of course, Equations 1 and 5 may be applied to the spring wire 168 connected to the detection coil 164 to improve the reliability.

Hereinafter, a second embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

As shown in FIG. 19A, the actuator 200 includes a movable plate 202, a torsionally flexible spring 204 which is an elastic member extending from the movable plate 202, and a support for supporting the torsionally flexible spring 204 in a cantilever manner. And a piezoelectric element 208 for holding the support portion 206.

As can be seen from FIG. 19B, the movable plate 20
2 is the center axis EE ′ of the torsion flexible spring 204.
Is out of range. The support portion 206 is fixed to the piezoelectric element 208 by, for example, an adhesive.

The movable plate 202, the torsion flexure spring 204, and the support portion 206 are integrally formed with high processing accuracy by semiconductor manufacturing technology. This structure includes a silicon layer 212 and a metal film 214 covering the silicon layer 212, as shown in FIG.

An AC voltage of a desired frequency is applied to the piezoelectric element 208 from, for example, a power supply (not shown). The piezoelectric element 208 expands and contracts in the z direction at the frequency of the AC voltage in FIG. 19C in response to the application of the AC voltage. The expansion and contraction movement of the piezoelectric element 208 is transmitted to the movable plate 202 via the torsion bending spring 204, and the movable plate 202 bends in the z direction.

As described above, since the center of gravity of the movable plate 202 is displaced from the central axis EE ′ of the torsion flexure spring 204, the movable plate 202 is moved together with the flexure motion.
4 make a torsional movement about the central axis EE ′.

The metal film 214 formed on the movable plate 202
Functions as a reflection unit. Therefore, the light beam reflected by the reflecting section is deflected in accordance with the bending movement accompanied by the torsional movement of the movable plate 202.

The spring characteristic of the torsion flexure spring 204 is determined by the characteristic of the material of the silicon layer 212. Silicon layer 2
12 has high rigidity, but has low impact resistance, but the metal film 214 covering it, on the contrary, has high impact resistance. Accordingly, the torsion flexure spring 204 has both high rigidity and high impact resistance. As a result, an actuator having high impact resistance while having desired driving characteristics can be obtained.

The actuator of this embodiment is manufactured, for example, as follows.

Step 1 (FIG. 20): A shape corresponding to the movable plate 202, the torsion flexure spring 204, and the support portion 206 is formed on a silicon wafer 220 having both sides polished, using a resist. In FIG. 20, two pieces are shown,
The number is not limited to two and may be changed.

Step 2 (FIG. 21A): The silicon wafer 220 is etched using, for example, RIE with the resist formed in Step 1 as a mask, and corresponds to the movable plate 202, the torsion flexure spring 204, and the support section 206. Is formed and separated from the silicon wafer 220.
FIG. 21A shows the structure corresponding to one actuator.

Step 3 (FIGS. 21 (b), 21 (c), 21)
(c) is a cross-sectional view taken along the line FF 'in FIG. 21 (b)): The movable plate 202 and the torsion flexure spring 20 manufactured in step 2
Electroless plating of, for example, nickel is applied to the entire surface of the structure corresponding to the support 4 and the support portion 206. As a result, the entire surface of the silicon layer 212, which is a structure corresponding to the movable plate 202, the torsion bending spring 204, and the support portion 206, is covered with the nickel metal film 214.

Step 4 (see FIG. 19 (c)): The piezoelectric element 208 is attached to the support portion 206 of the structure thus manufactured by using, for example, an adhesive.

According to the present embodiment, an actuator having desired driving characteristics and high impact resistance is provided. In addition, since the member having high impact resistance is located outside the member having high rigidity, even when the portion of the elastic member becomes the point of application of the impact force when the actuator falls, the member having high impact resistance can be subjected to impact. Because it absorbs force, it is difficult for impact to be transmitted to highly rigid members.

A first modification of the second embodiment will be described with reference to FIG. In the figure, members that are functionally the same as the members of the second embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 22A shows an actuator of this modification.
FIG. 22 which is a cross-sectional view taken along line EE ′ of FIG. 22 (A).
As shown in (B), except for a part of the movable plate 202,
Movable plate 202, torsion flexible spring 204, and support 106
Has a polyimide layer 230 on its upper surface. Movable plate 2
02 which is not covered with the polyimide layer is the metal film 2
14 is exposed, and functions as a reflection portion 232.

The polyimide layer 230 is formed, for example, by forming a film on the upper surface by, for example, a jet printing system between the steps 3 and 4 of the manufacturing process in the second embodiment.

In the present modification, as shown in FIG. 22C and FIG. 22C which is a cross-sectional view taken along line FF ′ of FIG. The silicon layer 212 is covered with a metal film 214, and a polyimide layer 230 is further provided thereon. As described above, since the metal film 214 and the polyimide layer 230, which are members having high impact resistance, are provided on the outside of the member having high rigidity, the actuator according to the present modification has a higher impact resistance than the second embodiment. High in nature.

A second modification of the second embodiment will be described with reference to FIG. In the figure, members that are functionally the same as the members of the second embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 23A shows an actuator of this modification.
As shown in FIG. 4, a layer of a polymer material such as a resin, such as a polyimide layer, covering the entire surface of the movable plate 202, the torsion flexible spring 204, and the support portion 106 except for a part of the movable plate 202.
30. The portion of the movable plate 202 that is not covered with the polyimide layer has the metal film 214 exposed, and this functions as the reflection portion 232.

Such a polyimide layer 230 is formed, for example, by forming a film on the upper surface by, for example, a jet printing system between steps 3 and 4 of the manufacturing process in the second embodiment described above. Instead of coating the entire surface of the polyimide with a jet printing system, a film of a resin or a polymer material such as polyimide may be formed by a technique such as potting or dipping. In this case, since it is difficult in mass production to selectively expose the metal film 214 only on a part of the movable plate 202 as in a jet printing system, a mirror is attached to the movable plate 202 with an adhesive or the like after polyimide is formed. It is good to attach.

In this modification, as can be seen from FIG. 23A and FIG. 23B which is a cross-sectional view taken along line FF ′ of FIG. 23A, the spring characteristics of the torsion bending spring 204 are determined. The silicon layer 212 is covered with a metal film 214, and the metal film 214 is almost covered with a polyimide layer 230. As described above, since the member having high rigidity is covered with the metal film 214 and the polyimide layer 230 which are members having high impact resistance, the actuator of the present modification is different from the first modification of the second embodiment. Also have higher impact resistance.

When a desired thickness cannot be obtained by a single film formation using a jet printing system or potting or dipping, for example, as shown in FIG. The polyimide layer 234 may be formed by the second deposition on the polyimide layer 230 formed by the first deposition. The film formation process may be performed three or more times.

A third modification of the second embodiment will be described with reference to FIG. In the figure, members that are functionally the same as the members of the second embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 24, the actuator of this modification has the entire surface of the movable plate 202, the torsion flexure spring 204, and the support portion 106 except for a part of the movable plate 202 and a portion of the torsion flexure spring 204. Polyimide layer 23 covering
It has 0. The portion of the movable plate 202 that is not covered with the polyimide layer has the metal film 214 exposed, and functions as the reflection portion 232. Also, the torsion flexure spring 204
The portion not covered by the polyimide layer is a metal film 214
Are exposed, and function as the position detecting reflector 236.

The polyimide layer 230 is formed, for example, by the same method as the second modification of the second embodiment.

The light beam emitted from the position detecting light source 238 is reflected by the position detecting reflector 236 and detected by the light detecting array 240.
2 is performed. The position detecting reflector 236 may be divided by about 5 to 10% by a beam splitter into a light beam irradiated to the reflector 232 for deflection, and may be irradiated.

A fourth modification of the second embodiment will be described with reference to FIG. In the figure, members that are functionally the same as the members of the second embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 25 (A), the actuator of this modification has the same appearance as that of the second embodiment, and the driving principle is the same as that of the second embodiment.

25B and FF 'in FIGS. 25A and 25B.
As can be seen from FIG. 25C, which is a cross-sectional view taken along the line, the structure of the movable plate 202, the torsion flexure spring 204, and the support portion 206 includes a hollow gold film 242, a chrome film 244 covering the outside thereof, And a polyimide layer 246 further covering the outside.

In this modification, the gold film 242 and the chromium film 244 are members having high rigidity but low impact resistance, and the polyimide layer 246 is a member having high impact resistance.

The actuator of this modification is manufactured, for example, as follows. Since the first step is similar to the step of the second embodiment, it will be briefly described.

Step 1 (see FIG. 20): The step of replacing the silicon wafer of the second embodiment with a glass substrate is performed.

Step 2 (FIG. 26A): A glass structure 250 having a shape corresponding to the movable plate 202, the torsion flexure spring 204, and the support portion 206 by etching glass instead of silicon in the second embodiment. To form RI
When E is used, it is performed by a device for glass etching.

Step 3 (FIG. 26B): Glass structure 250
A gold film 242 is formed on almost the entire surface by gold, for example, by electroless plating. At the time of plating, by holding a part of the glass structure 250 so as not to be exposed to the plating solution, plating is not applied to a part of the support portion, and a portion where the glass structure 250 is exposed is left.

Step 4 (FIG. 26C): This structure is immersed in a hydrogen fluoride solution to etch only the glass structure 250. The gold film 242 remains intact without being affected by the hydrogen fluoride solution, resulting in a hollow structure.

Step 5 (FIG. 26D): A chromium film 244 is formed on almost the entire surface outside the hollow gold film 242 by, for example, electroless plating. At the time of plating, the hollow gold film 242 is held by an appropriate holding means so that the opening of the hollow gold film 242 is not immersed in the plating solution so that the plating solution does not enter the inside of the hollow gold film 242.

Step 6 (FIG. 26E): A polyimide layer 246 is formed on the entire surface of the chromium film 244 by, for example, potting. At the time of potting, the hollow gold film 24
The hollow structure is held by an appropriate holding means so that the opening is not immersed in the polyimide solution, so that the polyimide solution does not enter the inside of 2.

Step 7 (see FIG. 25B): The piezoelectric element 208 is attached to the support portion 206 using an adhesive or the like to complete the actuator of this modification.

In this modification, a sufficient thickness cannot be obtained by only one gold plating, and thus a sufficient rigidity cannot be obtained. Rigidity was obtained. Of course, when the desired rigidity can be obtained only by one time of gold plating, as shown in FIG. 25 (D), chrome plating is omitted and directly on the gold film 242.
A polyimide layer 246 may be formed.

In the present modification, the torsion flexible spring 204 has a hollow structure. Comparing the hollow structure and the solid structure, the hollow structure generally has higher torsional rigidity at the same cross-sectional area. Therefore, if a rigid member is made hollow,
In addition to the properties of the material, the rigidity can be further increased. As described above, in the present modification, the torsion flexible spring 204 has high rigidity based on the structural characteristics in addition to the properties of the material.

Further, in the actuator of this modification, the movable plate 202 has a hollow structure in addition to the torsion flexible spring 204. Thus, the weight of the movable plate 202 is reduced, and therefore, the moment of inertia of the movable plate 202 is small. For this reason, the resonance frequency of the actuator can be increased as necessary.

In the actuator of this modified example, the member having high shock resistance is provided outside the member having high rigidity. Therefore, when the actuator falls, the elastic member becomes the point of application of the impact force. However, since the member having high impact resistance absorbs the impact force, it is difficult for the impact to be transmitted to the member having high rigidity. That is, the actuator of the present modification has high impact resistance.

In step 4 described above, only the glass corresponding to the support portion 206 and the torsion flexure spring 204 is etched by controlling the amount of etching of the glass with the hydrogen fluoride solution by controlling the etching time. The glass corresponding to the movable plate 202 may be left. In this case, the movable plate 202 having high rigidity is obtained. In step 1 described above, a silicon wafer may be used instead of a glass substrate as in the second embodiment. In this case, silicon may be etched using a mixed solution of a hydrogen fluoride solution and nitric acid instead of the hydrogen fluoride solution in the above-described step 4.

A fifth modification of the second embodiment will be described with reference to FIG. In the figure, members that are functionally the same as the members of the second embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 27, the actuator of the present modification has a movable plate 202 and a torsion flexure spring 204.
The support 206 comprises a polyimide layer 252 and a phosphor bronze film 254 covering the polyimide layer 252. In this modification, the phosphor bronze film 254 is a member having high rigidity, and the polyimide layer 252 is a member having high impact resistance.

Such an actuator is manufactured, for example, as follows. Since the steps are similar to those of the second embodiment, the description will be simplified.

Step 1 (see FIG. 20): The step of replacing the silicon wafer of the second embodiment with a polyimide substrate is performed.

Step 2 (see FIG. 21A): The polyimide is etched instead of silicon in the second embodiment, and the movable plate 202, the torsion flexure spring 204 and the support 2 are etched.
A polyimide structure having a shape corresponding to 06 is formed. When RIE is used, the setting is performed for polyimide.

Step 3 (see FIG. 21B): Phosphor bronze is electrolessly plated on the entire surface of the polyimide structure instead of nickel in the second embodiment.

Step 4 (FIG. 27A, FF 'in FIG. 27A)
FIG. 27 (B) is a cross-sectional view along the line: The piezoelectric element 208 is attached to the support portion 206 using an adhesive or the like, and the actuator of the present modification is completed.

When the hollow structure is compared with the solid structure, the hollow structure generally has higher torsional rigidity at the same sectional area. Therefore, when a member having high rigidity is formed into a hollow structure, the rigidity can be further increased in addition to the properties of the material. In this modification, the torsion flexure spring 204 is equivalent to a structure in which the internal space of a hollow structure of a member having high rigidity is filled with a member having high impact resistance. Therefore, it has high rigidity and high impact resistance.

A sixth modification of the second embodiment will be described with reference to FIG. In the figure, members that are functionally the same as the members of the second embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 28A shows an actuator of this modification.
FIG. 28 is a sectional view taken along line FF ′ of FIG.
As shown in (B), the movable plate 202, the torsion flexure spring 204, and the support portion 206 are composed of a polyimide layer 252, a phosphor bronze film 254 covering the whole surface thereof, and a phosphor bronze film 254.
And a polyimide layer 256 covering the entire surface of the substrate 54. In this modification, the phosphor bronze film 254 is a member having high rigidity, and the inner polyimide layer 252 and the outer polyimide layer 256 are members having high impact resistance.

In such an actuator, for example, after the step 3 in the fifth modification, the polyimide layer 256 is formed on the entire surface of the phosphor bronze film 254 by, for example, a jet printing system.
08 is attached.

In the actuator of this modified example, since the polyimide layer 256 having high impact resistance is provided outside the phosphor bronze film 254 which is a member having high rigidity, it is higher than that of the fifth modified example. Has impact resistance.

In the formation of the outer polyimide layer 256, if the desired thickness cannot be obtained by one film formation, for example, as shown in FIG. The polyimide layer 25 formed in the first film formation
On polyimide film 6, a polyimide layer 258 may be formed by a second film formation. The film formation process may be performed three or more times.

In the above-described second embodiment and its modifications, an actuator having a torsion flexible spring has been described as an example. However, the present invention is not limited to this, and includes an actuator having a flexible spring, for example. .

Further, in the first embodiment and its modification, and in the second embodiment and its modification, an electromagnetically driven actuator which generates and drives a force by the interaction of a magnetic field and a current, and responds to a voltage application. Although a piezoelectric element type actuator using a piezoelectric element which expands and contracts has been described as an example, the principle of driving is not limited to these, and an actuator driven by other principles is also included in the present invention.

Although some embodiments have been described in detail with reference to the drawings, the present invention is not limited to the above-described embodiments, and may be carried out without departing from the scope of the invention. Including all implementations.

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

1. The actuator includes a movable plate, an elastic member extending from the movable plate, and a support portion that supports the movable plate via the elastic member. In an actuator in which the movable plate can move relative to the support portion, the elastic member has high rigidity. An actuator including a member and a member having high impact resistance, wherein the member having high rigidity is a main member that determines the elastic modulus of the entire elastic member, and thereby the elastic member has both high rigidity and high impact resistance. .

(Function / Effect) By forming an elastic member having high rigidity with a member having high impact resistance while absorbing a shock with a member having high impact resistance, it is possible to obtain desired rigidity while improving impact resistance. Can be

[0161] 2. 2. The actuator according to claim 1, wherein the highly rigid member has a hollow structure.

(Effects) When the shape of the torsion spring is compared between the case of the solid shaft and the case of the hollow shaft, the torsional rigidity is generally higher in the case of the hollow shaft if the sectional area is the same.
Therefore, when a member having high rigidity is formed on the hollow shaft, there is an effect that the rigidity can be easily increased from the shape in addition to the properties of the material.

3. 2. The actuator according to claim 1, wherein the member having high rigidity covers the member having high impact resistance.

(Function and Effect) By providing a member having high impact resistance in the hollow portion of the hollow shaft formed of a member having higher rigidity, the impact resistance can be enhanced.

[0165] 4. 2. The actuator according to claim 1, wherein the member having high impact resistance covers the member having high rigidity.

(Function / Effect) Since the member having high impact resistance is located outside the member having high rigidity, even if the elastic member becomes the point of application of the impact force when the actuator falls, the impact resistance is reduced. High members absorb the impact force,
As a result, the impact is hardly transmitted to the member having high rigidity, and high impact resistance is obtained.

[0167] 5. 2. The actuator according to claim 1, wherein the elastic member includes a planar layer of a highly rigid member and a planar layer of a highly impact-resistant member stacked on each other.

(Function / Effect) When the thickness of the member is insufficient for a desired thickness in one film forming step, a plurality of layers are formed by performing a plurality of film forming steps to obtain a desired layer. The thickness can be secured.

6. Further provided is a wiring passing through the inside of the elastic member, wherein the wiring is disposed at or near a position where the generated strain is least in a cross section of the elastic member perpendicular to a straight line connecting the movable plate and the support portion. The actuator according to claim 1, wherein

(Function and Effect) For example, the actuator can be easily manufactured by a manufacturing technique of stacking flat layers such as a general semiconductor manufacturing technique or a printed wiring board manufacturing technique.

When the plane layer has an internal stress, the stress can be relaxed / canceled by overlapping the plane layer having a tensile stress and the plane layer having a compressive stress in some cases. By maintaining the desired shape, the characteristics of the actuator caused by the elastic member may be able to be made as desired.

In the case where the plane layer has an internal stress, the stress can be relaxed / canceled by overlapping the plane layer having a tensile stress and the plane layer having a compressive stress in some cases, thereby preventing deformation of the elastic member. By maintaining the desired shape, the characteristics of the actuator caused by the elastic member can be made as desired.

When the flat layer having high impact resistance is the end layer of the elastic member, when the elastic member acts as a point of action and an impact force is applied, the flat layer having high impact resistance absorbs and the impact resistance is reduced. improves. Further, when the flat layer having high impact resistance is a layer at both ends of the elastic member, the effect is further improved.

[0174] 7. The wiring exists at the interface between the high rigidity member and the high impact resistance member, and the thickness of the high rigidity member is t ₂ ,
The transverse elastic modulus is G ₂ , the thickness of the high impact resistant member is t ₁ , the transverse elastic modulus is G ₁ , and the width of the elastic member is q,
When the shape of the elastic member is q> 2t ₁ and q> 2t ₂ , k ₁ ≡ (１) −0.21 × (2t ₁ / q) × (1- (2t ₁
/ q) ⁴ ), k ₂ ≡ (1/3) −0.21 × (2t ₂ / q) × (1-
(2t ₂ / q) ⁴ ), t ₁ and t ₂ (G ₂ k ₂ / G ₁ k ₁ )
^1/3 substantially matches, or the shape of the elastic member is q ≦ 2t ₁
And when q ≦ 2t ₂ , k ₁ ≡ (３) −0.21 ×
(q / 2t ₁ ) × (1− (q / 2t ₁ ) ⁴ ), k ₂ ≡ (３) −0.2
When 1 × (q / 2t ₂ ) × (1− (q / 2t ₂ ) ⁴ ), t ₁
And t ₂ (G ₂ k ₂ / G ₁ k ₁ ) approximately match, or when the shape of the elastic member satisfies 2t ₂ ≦ q ≦ 2t ₁ , k ₁ ≡ (1/1 /
3) −0.21 × (q / 2t ₁ ) × (1− (q / 2t ₁ ) ⁴ ), k ₂ ≡
When (1/3) −0.21 × (2t ₂ / q) × (1− (2t ₂ / q) ⁴ ), t ₁ and 4t ₂ ³ (G ₂ k ₂ / G ₁ k ₁ ) Item 7. The actuator according to Item 6, wherein q- ² substantially coincides with q- ² .

(Function / Effect) If there is a wiring on the surface of the elastic member, the stress is large and there is a problem such as disconnection. It becomes difficult.

8. The wiring exists at the interface between the high rigidity member and the high impact resistance member, and the thickness of the high rigidity member is t ₂ ,
Assuming that the longitudinal elastic modulus is E ₂ , the thickness of the member having high impact resistance is t ₁ , and the longitudinal elastic modulus is E ₁ , t ₁ and t ₂ (E ₂ / E ₁ )
Item 7. The actuator according to item 6, wherein ^1/3 substantially matches.

(Function / Effect) If there is a wiring on the surface of the elastic member, the stress is large and there is a problem such as disconnection. However, if the above conditions are satisfied, the wiring is arranged at the position in the elastic member where the distortion is the smallest. The stress acting on the wiring is small and the disconnection is difficult.

[0178]

According to the present invention, an actuator having sufficient rigidity to obtain desired characteristics and high impact resistance is provided.

[Brief description of the drawings]

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

FIG. 2 is a plan view in which a permanent magnet of the actuator shown in FIG. 1 is omitted.

FIG. 3 is a cross-sectional view of the actuator taken along line AA ′ of FIG. 2;

FIG. 4 is a sectional view of the actuator taken along line BB ′ of FIG. 2;

FIG. 5 shows a first half of a manufacturing process of the actuator shown in FIG. 1;

FIG. 6 shows a manufacturing step in the latter half of the actuator shown in FIG. 1 subsequent to the step shown in FIG. 5;

FIG. 7 schematically shows an actuator formed on one SOI substrate.

8 is a view showing an actuator of a first modified example of the first embodiment, and is a cross-sectional view of a step that follows Step 10 in FIG. 6D, and the cross section is a line CB ′ in FIG. 2; Corresponds to the cross section broken along the line.

9 is a view showing an actuator of a second modified example of the first embodiment, and is a cross-sectional view of a step that follows Step 10 in FIG. 6D, and the cross section is a line CB ′ in FIG. 2; Corresponds to the cross section broken along the line.

FIG. 10 is a view for explaining a manufacturing process of an actuator according to a third modified example of the first embodiment. The manufacturing process is the same as the manufacturing process of the first embodiment up to the middle. The step following the step 6 is shown.

FIG. 11 is a view for explaining a manufacturing process of the actuator according to the third modification of the first embodiment, and shows a step following FIG. 10;

FIG. 12 shows a cross section cut along the line DD ′ of FIG. 11 (b).

FIG. 13 is a cross-sectional view illustrating an actuator according to a fourth modification of the first embodiment, and the cross section corresponds to a cross section cut along line BB ′ in FIG. 2;

14 is a cross-sectional view illustrating an actuator according to a fifth modified example of the first embodiment, and the cross section corresponds to a cross section cut along line CB ′ in FIG. 2;

FIG. 15 is a diagram for explaining an actuator according to a sixth modification of the first embodiment, and shows a cross-sectional model of a torsion spring.

FIG. 16A is a perspective view of an actuator according to a seventh modification of the first embodiment, FIG. 16B is a cross-sectional view taken along line LL ′ of FIG. FIG. 4B is a cross-sectional view taken along line LL ′ of FIG. 3A in an example in which three spring lines pass through one torsion spring.

FIG. 17A is a perspective view of an actuator according to an eighth modification of the first embodiment, and FIG. 17B is a cross-sectional view taken along line LL ′ of FIG.

FIG. 18 is a perspective view of an actuator according to an eighth modification of the first embodiment.

19A is a perspective view of the actuator according to the second embodiment, FIG. 19B is a plan view of the actuator according to the second embodiment, and FIG. 19C is a view taken along line EE ′ of FIG. It is sectional drawing of the actuator of 2nd Embodiment fractured | ruptured.

FIG. 20 illustrates an initial step in a manufacturing process of the actuator illustrated in FIG. 19;

FIG. 21 shows a step of manufacturing the actuator shown in FIG. 19;

22A is a perspective view of an actuator according to a first modification of the second embodiment, FIG. 22B is a cross-sectional view of the actuator taken along line EE ′ of FIG. C) is the F of (B)
It is sectional drawing of the actuator cut | disconnected along the -F 'line.

FIG. 23A is a cross-sectional view of an actuator according to a second modification of the second embodiment, and its cross-section is taken along line E-E of FIG. 19B.
(B) corresponds to the cross section broken along the line E '.
3A is a cross-sectional view of the actuator taken along the line FF ′ in FIG. 3A, and FIG. 3C is a cross-sectional view corresponding to (B) of the actuator in which the polyimide layer is formed twice. FIG.

FIG. 24 is a cross-sectional view of an actuator according to a third modification of the second embodiment, and the cross-section corresponds to a cross-section taken along line EE ′ of FIG. 19B.

FIG. 25A is a plan view of an actuator according to a fourth modified example of the second embodiment, and FIG. 25B is a cross-sectional view of the actuator taken along line EE ′ in FIG. And (C)
FIG. 3B is a cross-sectional view of the actuator taken along line FF ′ in FIG. 3B, and FIG. 4D is a cross-sectional view corresponding to (C) of the actuator in which the chromium film is omitted.

FIG. 26 shows a step of manufacturing the actuator shown in FIG. 25.

FIG. 27A is a cross-sectional view of an actuator according to a fifth modified example of the second embodiment, and its cross-section is taken along line E-E of FIG. 19B.
(B) corresponds to the cross section broken along the line E '.
FIG. 3A is a cross-sectional view of the actuator taken along line FF ′ of FIG.

FIG. 28A is a cross-sectional view of an actuator according to a sixth modification of the second embodiment, and its cross-section is taken along line E-E of FIG. 19B.
(B) corresponds to the cross section broken along the line E '.
3A is a cross-sectional view of the actuator taken along the line FF ′ in FIG. 3A, and FIG. 3C is a cross-sectional view corresponding to (B) of the actuator in which the polyimide layer is formed twice. FIG.

[Explanation of symbols]

 Reference Signs List 102 movable plate 104 torsion spring 106 support 116 active layer (silicon layer) 140 polyimide layer

Claims (3)

[Claims] 1. An actuator comprising: a movable plate; an elastic member extending from the movable plate; and a support portion for supporting the movable plate via the elastic member, wherein the movable member is movable with respect to the support portion. Including a high-rigidity elastic material and a high-impact-resistance elastic material, the high-rigidity elastic material is a main material that determines the elastic modulus of the entire elastic member, whereby the elastic member has high rigidity and high impact resistance. Actuator that has both. 2. The actuator according to claim 1, wherein the high-impact elastic material covers the high-rigidity elastic material. 3. The apparatus according to claim 1, further comprising: a wire passing through the inside of the elastic member, wherein the wire is located at a position where the generated strain is least in a cross section of the elastic member perpendicular to a straight line connecting the movable plate and the support portion, or at a position thereof. The actuator according to claim 1, wherein the actuator is disposed in the vicinity.