JPH0965491A - Electromechanical transducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromechanical transducer using a subminiature integrated electrostatic actuator with a high efficiency by arranging a stator and a moving part opposite to each other so as to control an electrostatic force between them. SOLUTION: The electroacoustic transducer using the integrated electrostatic actuator formed by the micro machine technology is made up of the integrated electrostatic actuator 1, a power supply and controller 2, a signal and power supply connection section 3, a moving part 4, and a transmission part 5. A drive power and an operating signal are fed from the power supply and controller 2 to the electrostatic actuator 1 via the connection part 3. The electrostatic actuator 1 provides a mechanical motion to the moving part 4 via the transmission part 5 according to an operation signal to move the moving part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electro-mechanical conversion device using an integrated electrostatic actuator manufactured by micromachine technology. More specifically, the electric signal is converted into mechanical movement or vice versa. The present invention relates to a microminiaturized system for converting physical movement into an electric signal.

[0002]

2. Description of the Related Art A conventional electro-mechanical conversion device, for example, a microphone or a speaker, converts a change in current flowing in an electromagnet into a mechanical movement, and vice versa. Was there.

[0003]

However, the conventional method using such an electromagnet has problems that the conversion efficiency of electric energy or mechanical energy is low and the dynamic range is small. Further, in the conventional conversion system, the size is limited by the electromagnet, so that miniaturization is impossible. All of these are due to the use of electromagnets in which electric wires are wound many times.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and the conversion efficiency is improved by an electro-mechanical conversion system using an integrated electrostatic actuator made by micromachine technology. It has a high dynamic range and a large dynamic range. That is, using an integrated electrostatic actuator,
It proposes a microminiature system that converts an electrical signal into a mechanical movement, or vice versa.

[0005]

The electro-mechanical conversion system using the integrated electrostatic actuator manufactured by the micromachine technology according to the present invention is as shown in FIG.
And a power supply and control device 2 for supplying signals and electric power thereto, a signal and electric power supply connecting portion 3, and a transmitting portion 5 connecting the integrated actuator 1 and the movable portion 4. When the operation signal is transmitted through the connection portion 3 while supplying the driving power to the electrostatic actuator 1 from the power source and the control device 2, the electrostatic actuator 1 performs the mechanical motion according to the operation signal. It transmits to the movable part 4 through the transmission part 5, and moves the movable part.

On the contrary, the movement of the movable portion 4 is transmitted to the electrostatic actuator 1 through the transmission portion 5, and an electric signal corresponding to the movement of the movable portion 4 is transferred to the electrostatic actuator 1.
Generated by the control unit 2, transmitted to the control unit 2 through the connection unit 3, and taken out as a signal. Since only the charging current effectively flows through the electrostatic actuator 1, the efficiency can be made very high, and the efficiency can be improved as compared with the conventional system.

The size of the electrostatic actuator 1 is
The size can be made very small because it is formed by micromachine technology using semiconductor fine processing technology. For example, if the minimum processing size is 0.5 μm, the size of only the main body of the electrostatic actuator 1 can be 1 mm or less. The size can be reduced to 1/10 or less as compared with the structure using the conventional coil.

[0008]

【Example】

Example 1 This example discloses the structure of an electrostatic actuator.
FIG. 2A is a schematic view of the structure of the electrostatic actuator having the simplest structure, and shows a state in which the comb tooth-shaped electrodes 13 are formed in a nested manner in the structures 11 and 12 made of a conductor. When a voltage V is applied between the electrodes of the conductors 11 and 12, these conductors 11,
The force F acting between 12 is expressed by the following equation.

It is represented by F = αV (1). Where α is a constant of proportionality.

Therefore, when the conductor 11 is fixed and a voltage V is applied between the conductors 11 and 12, the conductor 1
For the displacement x of 2, the value represented by the following equation corresponding to the generated force F represented by the equation (1) is obtained.

X = βF (2) where β is a proportional constant.

Therefore, the relationship between the final displacement amount x and the applied voltage V is expressed by the following equation.

X = αβV (3) From equation (3), it is understood that there is a linear relationship between the displacement amount and the applied voltage, and the relationship can be uniquely defined as a structural parameter. Therefore, it is theoretically supported that the electro-mechanical conversion can be performed at a very high rate by setting appropriate structural parameters.

The basic structure of the comb-teeth-shaped electrodes 13 of the conductors 11 and 12 is that the comb-teeth-shaped electrodes 13 are alternately formed on one plane as shown in the sectional view of FIG. The cross-sectional view of FIG. 3 is seen in the direction of the arrow at the position AA in FIG. If the width of the tooth-shaped electrodes 13 of these combs is set to w1 and the spacing is set to w2, and the width and the spacing are made the same for simplification, the force F acting between these conductors 11 and 12 is calculated from the equation (1). The smaller w2 is, the larger it becomes. The reason for this is that the parameter α in the equation (1) is increased by increasing the capacitance between the electrodes. Therefore, it is necessary to reduce the interval w2 for higher sensitivity.

In the sectional view of the electrode shown in FIG. 3, the width and the thickness of the electrode are almost the same, but this is not necessarily a necessary condition, and the mechanical strength of the electrode and the natural frequency of the electrode are It is an amount that is determined by an evaluation parameter such as an affected weight.

On the other hand, when the capacitance between the electrodes is increased, the charging current for the electrode capacitance flows as described above, which causes a problem that the power consumption increases. Therefore, the value of w2 is a value that is a balance between the required force and the power consumption. Need to decide. Suitable w
The value of 2 and the width of the entire electrostatic actuator were generally about 0.1 μm to 10 μm and 3 μm to 1500 μm, respectively, but particularly 0.2 μm to 1 μm and 10 μm.
In the range of m to 200 μm, miniaturization and supersensitivity could be achieved at the same time. It goes without saying that the value of w2 and the value of the width of the entire electrostatic actuator have some differences depending on the application, and an appropriate value can be selected depending on each application.

The structure shown in FIG. 3 can be easily designed by a skilled expert and can be realized by an ordinary semiconductor fine processing technique. That is, by growing a sacrificial layer such as a silicon oxide film on a silicon wafer, depositing a thin film made of a material such as polycrystalline silicon on the sacrificial layer, and processing the sacrificial layer, the sacrificial layer made of the silicon oxide film is removed. The electrostatic actuator structure can be realized.

As shown in FIGS. 2A and 3, the electrostatic actuator does not necessarily have to be a comb-shaped electrode. For example, it is possible to obtain the same action with a parallel plate electrode. However, it is clear that the comb electrode structure or a structure similar thereto has the highest efficiency. For example, as shown in FIG. 2B, a structure in which the movable electrodes 15 are formed between the fixed electrodes 14 and 16 so that the comb electrodes are nested with each other is also effective.

It is clear that such a comb-shaped electrode structure can be formed not only in the horizontal direction as shown here, but also in the vertical direction. Further, the voltage application method is not limited to a method in which one electrode is grounded and a voltage is applied between both electrodes. For example, in FIG. The structure 12 made of a body is displaced by a spring structure, for example, to the right in the plane of the drawing, and the amount of the displacement is compensated by the voltage applied between the structures 11 and 12 made of the conductor. The structure 12 made of a conductor of the electrostatic actuator that operates only in the right direction in the drawing and has a small distance can be operated in both left and right directions in the drawing plane.

In FIG. 2B, the structure 15 made of a conductor is set to the ground potential, and a positive and negative voltage is applied to the structure 14 made of a conductor and the structure 16 made of a conductor. Allows proper operation of the electrostatic actuator. In this case, the structures 14, 16
Should be structurally fixed and the connecting arm should be taken out from the structure 15 so that the movement of the structure 15 can be utilized.

Embodiment 2 This embodiment discloses a structure of a speaker using an electrostatic actuator. FIG. 4 shows a structure including an electrostatic actuator 21 and a speaker 23 mechanically connected to the electrostatic actuator 21 via a connecting portion 22. When an electric signal is input to the electrostatic actuator 21 from the signal generator 24 through the cable 25, the electrostatic actuator 21
Operate according to the electrical signal. Transmitting this mechanical actuation to the speaker via the connecting portion 22,
Finally, the electric signal from the signal generator becomes sound.

In this embodiment, w2 is set to 0.3 μm, and the width of the entire electrostatic actuator is set to about 100 μm. In general, a sufficient force can be generated. In this case, the natural frequency of the electrostatic actuator 21 is about 3
Since the frequency can be set sufficiently high as 0 kHz, a complete frequency response was obtained in a wide range from bass to treble. On the other hand, in order to realize a large speaker, the electrostatic actuator 21
Needless to say, it is necessary to increase, but at this time, the natural frequency becomes small, and therefore the response to high frequencies becomes small.

A detailed structure of the electrostatic actuator 21 shown in FIG. 4 is shown in FIG. The electrostatic actuator including the comb-shaped electrode 31, the connecting portion 32 connected to the electrostatic actuator, and the vibration plate 33 are fixed to the frame 34. The mechanical vibration of the comb-shaped electrode 31 actuates the diaphragm 33 to change it into sound energy. The vibration plate 33 may be made of any material having a good vibration frequency response, for example, diamond, paper, plastic, metal or the like can be used.
In addition, it is necessary to use a material for the connecting portion 32 that does not deform due to vibration and does not cause vibration damping. For example, ceramic, hard plastic, etc. can be used, but this material is not necessarily an essential requirement of the invention.

Embodiment 3 This embodiment discloses the structure of a microphone using an electrostatic actuator. FIG. 6 shows the vibration plate 41 and the connecting structure 4.
2. In the structure including the electrostatic actuator 43, the electric signal transmission portion 44, and the electric signal control device 45, the sound from the outside is converted into mechanical motion by the diaphragm 41, and the electrostatic actuator 43 by the coupling mechanism 42. Be transmitted to. The mechanical vibration is converted into an electric signal by the electrostatic actuator 43, the electric signal reaches the electric signal control device 45 through the electric signal transmitting portion 44, and is taken out as an electric signal to the outside.

Needless to say, the conversion of mechanical vibration by the electrostatic actuator 43 into an electric signal can be performed by measuring the electrostatic capacitance by the operation of the comb electrodes, but a more accurate conversion method is to measure the tunnel current. It is due to. To explain this in detail, in the configuration shown in FIG. 7, the vibration excited in the diaphragm 53 is transmitted to the electrostatic actuator composed of the comb-shaped electrode 51 by the connecting structure 52. The comb-shaped electrode 51 has a portion 5 that functions as a probe.
5 and a portion 56 functioning as a counter electrode, and between the comb electrodes 51 so that the tunnel current flowing between the portion 55 functioning as the probe and the portion 56 functioning as the counter electrode becomes constant. By controlling the voltage applied to, it is possible to detect a movement of the diaphragm 53 of only about 0.1 nm or less and convert it into an electric signal, so that a very sensitive microphone can be realized. Therefore,
Since it becomes possible to detect even minute air vibrations that were impossible in the past, its engineering significance is great.

Embodiment 4 This embodiment discloses the structure of a micro radio using an electrostatic actuator. FIG. 8 shows a receiver 74, an electric signal transmitting portion 75, an electrostatic actuator 71, a mechanical connecting portion 72,
In the structure including the speaker 73, the electric wave received by the receiver 74 is converted into an electric signal, and the electrostatic actuator 71 is operated through the electric signal transmitting portion 75. The mechanical vibration generated by the electrostatic actuator 71 moves the mechanical connecting portion 72 and is transmitted to the speaker 73 as vibration. The vibration transmitted to the speaker 73 vibrates the air as a sound, and this device functions as a radio.

The features of the micro radio according to the present invention are that it is small in size and consumes minimum power. For example, if the receiver 74, the electric signal transmitting portion 75, the electrostatic actuator 71, the mechanical connecting portion 72, and the speaker 73 are formed on the same chip by the semiconductor processing technology, the whole is integrated into an area within a few millimeters square. It is possible. Further, the driving battery is small, and it is possible to integrate it on the chip in the form of a solar cell or the like. For example, in this embodiment, all functions can be integrated in a chip size of 3 mm square by the integrated circuit technology with the minimum processing size of 0.5 μm. The micro radio according to the invention can be attached to the tip of a writing instrument and used for personal background music. It can also be used as a personal radio in the form of earrings and placed directly near the ears. There is no need to use inconvenient shapes such as earphones and radios as in the past,
In addition, since the energy is small, the efficiency is high and the energy can be saved. Therefore, the engineering meaning is great.

Embodiment 5 This embodiment discloses the structure of a one-chip scanning tunnel microscope using an electrostatic actuator. In FIG. 9, a first electrostatic actuator 81 and a second electrostatic actuator 82 are connected to a probe 85 by connecting structures 83 and 84, respectively, and one electrode of each of the electrostatic actuators 81 and 82 is a frame. The state of being fixed to 86 is shown. Further, a third electrostatic actuator (not shown) is formed in the vertical direction on the paper surface of FIG. In such a structure, the probe 85 is moved by the first electrostatic actuator 81 and the second electrostatic actuator 82 in the left and right direction and the up and down direction on the paper surface of FIG. Figure 9 with electrodes
Moved up and down the page. With such a structure, a scanning tunneling microscope capable of three-dimensional operation using an electrostatic actuator can be realized.

A one-chip scanning tunnel microscope can be constructed by using the scanning tunnel microscope capable of three-dimensional operation disclosed in FIG. FIG. 10 shows this configuration diagram. A scanning tunneling microscope microscope 92 shown in FIG. 9 and a control circuit of the scanning tunneling microscope 92 capable of three-dimensional operation shown in FIG. Device 93,
The storage device 94 necessary for the operation of the control circuit device, and the power supply device 95 for generating and / or storing the electric energy necessary for driving the control circuit device 93 and the storage device 94.
Consists of If necessary, the control circuit device 93 or /
The storage device 94 can also have a communication function. That is, it is possible to provide a function of transmitting and receiving data acquired by the one-chip scanning tunnel microscope or a signal instructing the operation of the one-chip scanning tunnel microscope. By providing these functions, it becomes possible to operate the one-chip scanning tunnel microscope without connecting to the outside with an electric wire and to capture the acquired data, so that the degree of freedom of operation is dramatically increased. To do.

Embodiment 6 This embodiment discloses a microminiature recording / reproducing apparatus using an electrostatic actuator. In FIG. 11, a first electrostatic actuator 101 and a second electrostatic actuator 102 are connected to a probe 105 by connecting structures 103 and 104, respectively, and one electrode of each of the electrostatic actuators 101 and 102 is a frame. The state of being fixed to 106 is shown. Further, a third electrostatic actuator (not shown) is formed in the vertical direction on the paper surface of FIG. In such a structure, the probe 105 is connected to the first electrostatic actuator 10
1 and the second electrostatic actuator 102.
It is moved in the left and right direction and the up and down direction of the paper surface, and is also moved in the up and down direction of the paper surface of FIG. 9 by a third electrode (not shown). An information recording medium 107 is installed so as to face the probe 105. With the probe 105, information can be recorded on the information recording medium 107 or information recorded on the information recording medium 107 can be read out.

FIG. 12 is a block diagram of a microminiature music reproducing apparatus using the microminiature recording and reproducing apparatus disclosed in FIG. On the chip 111, the microminiature recording / reproducing device 113 disclosed in FIG. 11, the control circuit 114, the control circuit memory circuit 115,
The power source 112 and the speaker 116 disclosed in FIG. 4 are provided. The size of the entire chip 111 is 0.
By using a fine processing technology of 5 μm, it is possible to make a square of about 3 mm. By fixing the chip 111 to the ear, the device is not a large-scale device like the conventional one, so that it is possible to mount the microminiature music reproducing device without any discomfort.

[0032]

As shown in the above embodiments, according to the present invention, a microminiature electric actuator using an integrated electrostatic actuator is used.
A mechanical conversion device can be realized. In addition, by applying this technology, it is possible to realize electro-mechanical conversion which is significantly smaller and more efficient than conventional ones, and therefore the technical and economic effects thereof are great.

[Brief description of drawings]

FIG. 1 is a diagram showing an electro-mechanical conversion system using an integrated electrostatic actuator produced by a micromachine technology according to the present invention.

FIG. 2A is a diagram showing a structure of an electrostatic actuator having the simplest structure. FIG. 6B is a view showing the structure of an electrostatic actuator in which movable electrodes are formed between fixed electrodes so that comb electrodes are nested with each other.

FIG. 3 is a diagram showing a cross-sectional basic structure of conductor portions of a comb-shaped fixed electrode and a comb-shaped movable electrode.

FIG. 4 is a diagram showing a structure of a speaker using an electrostatic actuator.

5 is a diagram showing a detailed structure of the electrostatic actuator shown in FIG.

FIG. 6 is a diagram showing a structure of a microphone using an electrostatic actuator.

FIG. 7 is a diagram showing a principle of a method of converting mechanical vibration by an electrostatic actuator into an electric signal by measuring a tunnel current.

FIG. 8 is a diagram showing a structure of a micro radio using an electrostatic actuator.

FIG. 9 is a diagram showing the structure of a one-chip scanning tunneling microscope using an electrostatic actuator.

FIG. 10 is a configuration diagram of a one-chip scanning tunnel microscope using a scanning tunnel microscope capable of three-dimensional operation.

FIG. 11 is a diagram showing the structure of a microminiature information recording / reproducing apparatus using an electrostatic actuator.

12 is a diagram showing a configuration of a microminiature music reproducing device using the microminiature information recording / reproducing device disclosed in FIG.

[Explanation of symbols]

1, 21, 43, 71, 81, 82, 101, 102:
Integrated electrostatic actuator, 2: power supply and control device,
3, 22, 32, 42, 52, 72, 83, 84, 9
5, 103, 104: connecting part, 4: movable part, 5, 25,
44 and 75: signal transmission parts, 11 and 12: conductors, 1
3, 14, 15, 16, 31, 51: electrodes, 23, 7
3: speaker, 24, 45, 93, 94: signal control device, 33, 41, 53: diaphragm, 34, 86, 106:
Frame, 55, 85, 105: probe, 56: counter electrode, 7
4: receiver, 91: one-chip scanning tunnel microscope chip, 92: scanning tunnel microscope capable of three-dimensional operation.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomihiro Hashizume, 2520 Akanuma, Hatoyama-cho, Hiki-gun, Saitama Stock Company Hitachi Research Laboratory (72) Inventor Seiji Heike 2520, Akanuma, Hatoyama-cho, Hiki-gun, Saitama Prefecture Stock Company Hitachi Basic Research Laboratory (72) Inventor Ratvic Mark 2520 Akanuma, Hatoyama-cho, Hiki-gun, Saitama Stock Company Hitachi Research Laboratory

Claims (5)

[Claims] 1. An electric device comprising an actuator in which a fixed portion and a movable portion are arranged so as to face each other, and an electrostatic force acting between them is controlled to control a relative movement amount. Machine conversion device. 2. The electrostatic actuator is manufactured in an integrated form by micromachine technology.
The electro-mechanical conversion device described. 3. A fixed part, a movable part arranged to face the fixed part, and an actuator for controlling a relative movement amount by controlling an electrostatic force acting between the fixed part and the fixed part. An electro-mechanical conversion device comprising: a variable portion that is displaced in cooperation with the movable portion, and a part of the variable portion is held by a member that mechanically cooperates with a support member that holds the fixed portion. . 4. The electrostatic actuator is manufactured in an integrated form by a micromachine technology.
The electro-mechanical conversion device described. 5. The electro-mechanical conversion device according to claim 1, wherein a relative movement amount between the fixed portion and a movable portion arranged to face the fixed portion is detected as a change in tunnel current.