JP3221290B2 - Acceleration sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an element for measuring various mechanical quantities, and more particularly to an acceleration sensor for measuring acceleration.

[0002]

2. Description of the Related Art In an acceleration sensor, a spring having a damping function is attached to a firm frame, and a mass is connected to the spring, and a relative displacement between the frame and the mass when an external force or vibration is applied to the frame. Forces and accelerations are obtained by measuring the electric signals and the like, and are roughly classified into four types: a piezoelectric type, a dynamic type, a servo type, and a strain gauge type.

[0003] A piezoelectric acceleration sensor uses a piezoelectric element,
The acceleration is obtained by detecting a charge generated when a force is applied to the piezoelectric element. The electrodynamic acceleration sensor obtains acceleration by detecting an electromotive force generated in proportion to the speed of a conductor moving in a magnetic field. The servo type acceleration sensor uses a pendulum, and detects acceleration by detecting a change in capacitance due to displacement of the pendulum by a current. There are two types of strain gauges: resistance strain gauges and semiconductor strain gauges. Resistance strain gauges are diaphragms (springs).
A resistance strain gauge is attached to a device and the like, and acceleration is obtained from the change in applied force and resistance. The semiconductor strain gauge type uses the piezoresistive effect of Si and Ge single crystals to apply the applied force and resistance. Is obtained from the change in

[0004] Such acceleration sensors include aircraft gyros, jet engine vibration and fatigue diagnosis, seismometers, analyzers, robot self-localization, airbag impact detection, machine vibration analysis, active suspension attitude detection,
It is used in many industrial fields such as detection of a control force for an anti-lock brake, and its use is considered to be further diversified in the future.

[0005] With the recent development of semiconductor microfabrication technology, micromachine technology for making micron-sized motors and manipulators and vacuum microelectronics technology for making micro vacuum tubes have been actively researched. I have.

[0006] In particular, vacuum microelectronics
A micron-sized vacuum microstructure with a built-in cold cathode and control electrode integrated on a substrate such as a semiconductor to realize a high-performance vacuum device based on the high speed of electrons in a vacuum and the integration of the structure. In contrast to current semiconductor devices, which utilize the transport phenomena of electrons in solids, they are characterized by utilizing the high speed of electrons in vacuum, good trajectory control, or coherence. It is.

The most important component in the vacuum microelectronics is a cold cathode that emits electrons into a vacuum, and field emission devices are currently being studied most widely as cold cathodes. Vertical and horizontal field emission devices are known, and these will be described with reference to FIG.

FIG . 8A is a perspective view schematically showing a field-emission element called a Spindt type, which is a kind of vertical field-emission element. As shown in this figure, in a vertical field emission device, a cathode electrode 2 made of a metal such as aluminum is provided on a substrate 1 such as silicon or glass.
Conical emitter 5 made of metal such as molybdenum
Are formed. An insulating layer 3 made of silicon dioxide (SiO ₂ ) or the like is formed on a portion of the cathode electrode 2 where the emitter 5 is not formed, and a gate electrode 4 is further formed thereon. An opening 6 is provided in the gate electrode 4 and the insulating layer 3, and the cone-shaped emitter 5 is located in the opening 6. That is, the tip of the cone-shaped emitter 5 faces the opening 6.

In such a configuration, since the distance between the gate electrode 4 and the tip of the cone of the emitter 5 is on the order of submicron, only a few tens of volts are required between the gate electrode 4 and the emitter 5. By applying the emitter-to-emitter voltage V _GE , electrons can be field-emitted from the emitter 5. When the anode electrode 7 to which the positive voltage _VA is applied is provided opposite to the gate electrode 4 so as to be separated from the gate electrode 4, electrons emitted from the emitter 5 by field emission can be collected by the anode electrode 7. You can do it.

FIG. 8B is a perspective view schematically showing a wedge-type field emission device which is an example of a horizontal field emission device. In this figure, 1 is a substrate, 5 is an emitter formed in a wedge shape on the substrate 1, 4 is a gate electrode also formed on the substrate 1, and 7 is an anode electrode also formed on the substrate 1. As shown in the figure, the emitter 5, the gate electrode 4, and the anode electrode 7 are arranged side by side in a plane. The distance from the tip of the emitter 5 to the gate electrode 4 is, for example, about 5 μm. The distance is, for example, about 20 μm.
By applying a positive gate-emitter voltage V _GE between the gate electrode 4 and the emitter 5, to generate a strong electric field between the gate and the emitter, thereby electrons from the tip of the emitter 5 is drawn into the vacuum. By applying a positive voltage _VA to the anode electrode 7, the electrons can be collected by the anode 7 electrode.

By using such vacuum microelectronics technology or micromachine technology, it is possible to realize an active element or a high-performance element which is extremely miniaturized and which is resistant to high temperature and radiation environment. Become.

[0012]

As described above, various types of acceleration sensors are known, and they are selectively used depending on the purpose of use, such as an acceleration detection range, an accuracy, a frequency range, a use temperature range, and a weight of an object to be measured. However, each has the following problems. That is, the piezoelectric acceleration sensor has a problem that its output is easily changed with a rapid temperature change, and is weak against a high temperature. The electrodynamic acceleration sensor has difficulty in detecting static displacement and acceleration in one direction, and has an electric circuit, which makes it difficult to reduce its size and weight. Furthermore, it has the property that high precision is required for the processing accuracy of the parts, which makes the parts expensive. The servo type acceleration sensor has a property that it is larger and heavier than the piezoelectric type, and the processing accuracy of the parts requires high precision and is expensive. The resistance strain gauge type acceleration sensor has a problem that the sensitivity is not so high, and the semiconductor strain gauge type acceleration sensor has a problem that the temperature characteristics are not so good.

Accordingly, the present invention is to apply the micromachine technology and the vacuum microelectronics technology to an acceleration sensor to provide a small, lightweight acceleration sensor having stable characteristics, high reliability, and high reliability. . Still another object of the present invention is to provide an acceleration sensor capable of detecting three-dimensional acceleration in one element.

[0014]

In order to achieve the above object, an acceleration sensor according to the present invention is formed in a cone shape.
Emitter and above the tip of the cone-shaped emitter
A gate electrode portion provided with an opening adjacent thereto;
Of the electron flow emitted from the emitter and passing through the opening
Transformers arranged in a direction substantially perpendicular to the traveling direction
And the displacement electrode part is disposed in a vacuum vessel, and the displacement electrode part is
Swing in three-dimensional direction by a spring part that can be deformed in the vacuum vessel
Movably supported and in at least two or more areas
Divided and based on the electron flow flowing in the divided area
To measure acceleration. A plurality of the displacement electrodes are arranged so that a three-dimensional direction of the acceleration can be detected. Further, the displacement electrode is an anode electrode or a deflection electrode. Further, an electronic circuit such as an A / D conversion circuit or an amplification circuit is provided on the same substrate.

[0015]

When the acceleration is applied, the displacement electrode supported by the elastically deformable spring structure is relatively displaced. Thus, when the displacement electrode is an anode electrode, the state of arrival of electrons at the anode electrode changes, and when the displacement electrode is a deflection electrode, the trajectory of electrons emitted from the field electron-emitting device. Is changed by the deflection electrode, and the state of electron arrival at the anode electrode changes. The acceleration can be measured by detecting the change in the state of arrival of the electrons as a change in the current. Further, by arranging a plurality of field emission devices, acceleration in a three-dimensional direction can be detected and measured. Further, since the field emission device is formed on the substrate, an electronic circuit such as an A / D conversion circuit or an amplification circuit for processing detection data can be formed on the same substrate.

[0016]

FIG. 1 shows a first embodiment of the acceleration sensor of the present invention.
This will be described with reference to FIG. FIG. 1A is a diagram illustrating an example of an electrode structure of the acceleration sensor according to the present invention. In this figure, 2 is a cathode electrode formed on a substrate,
Reference numeral 3 denotes an insulating layer formed on the cathode electrode 2, 4 denotes a gate electrode formed on the insulating layer 3, and 5 denotes an emitter formed on the cathode electrode 2. 7 is an anode electrode,
In this embodiment, it is divided into two parts a1 and a2. Numeral 8 denotes a displacement electrode disposed between the gate electrode 4 and the anode electrode 7 and supported by a spring attached to a frame. When a force or vibration is externally applied to the acceleration sensor, the displacement electrode 8 has an inertia. It is configured to be displaced by force in the direction of the arrow in the figure. In this embodiment, a deflection voltage is applied to the displacement electrode 8 to act as a deflection electrode for changing the trajectory of electrons emitted from the emitter 5.

In the device configured as described above, when the gate-emitter voltage V _GE is applied between the cathode electrode 2 and the gate electrode 4 and the anode voltage _VA is applied to the anode electrode 7 as described above, Electrons are field-emitted from 5 and are collected by the anode electrode 7. Here, as described above, the displacement electrode (deflection electrode) 8 are positive deflection electrode voltage V _D is applied, the direction of the arrow by the force and vibration from the outside, the displacement electrode (deflection electrode) 8 Figure , The trajectory of the electrons emitted from the emitter 5 is changed by the displacement of the displacement electrode (deflection electrode) 8, and the amount of electrons collected by the portions a 1 and a 2 of the anode electrode 7 is reduced. Differences occur. Therefore, the anode current flowing through the anode 7 (a1) divided into two by the displacement of the displacement electrode (deflection electrode) 8 and the anode 7 (a2)
Is different from the anode current flowing through the device, and by detecting the ratio (distribution ratio) of the two currents, the displacement of the displacement electrode (deflection electrode) 8, that is, the acceleration applied to the device can be measured. .

FIG. 2 shows this state, in which the trajectory of electrons emitted from the emitter 5 is analyzed. This figure shows the trajectory of electrons when the deflection electrode 8 moves to the right by 500 nm, and a part of the electrons emitted from the emitter 5 are captured by the deflection electrode 8.
It can be seen that the current density at the anode 7 is higher on the left side of the figure.

FIG. 1B shows that the anode voltage V _A = 20
0 [V], gate-emitter voltage V _GE = 100
The distribution ratio with respect to the deflection electrode moving distance when driven under the condition of [V] and the cathode voltage of 0 [V] is shown.
As shown in this figure, the deflection electrode voltage V _D is changed to the gate voltage V
When the same 100 [V] and _GE is deflection electrode 10 can not measure the acceleration does not change even distribution rate moves, the deflection electrode voltage V _D is 0.99 [V] and 20
In the case of 0 [V], a difference occurs between the anode currents flowing through the anode 7 (a1) and the anode 7 (a2), and it can be seen that a component of acceleration in the left-right direction (X direction) in the figure can be detected. .

When the displacement electrode (deflection electrode) 8 moves in the Z direction (up and down direction in the figure), the electrons emitted from the emitter 5 emit electrons, as can be seen from the analysis results of the electron orbit shown in FIG. The amount captured by the displacement electrode 8 varies. That is, when the displacement electrode 8 moves upward,
Since the number of electrons captured by the displacement electrode 8 increases and the number of electrons captured by the anode electrode 7 decreases, the anode current flowing through the anode electrode 7 (the divided anode electrode 7 (a1) and anode electrode 7 (The sum of the anode currents flowing through (a2)) decreases. On the other hand, when the displacement electrode 8 moves downward, the number of electrons captured by the displacement electrode 8 decreases and the number of electrons captured by the anode electrode 7 increases, so that the anode current flowing through the anode electrode 7 increases. I do. Therefore, the anode current (divided anode electrode 7 (a1) and anode electrode 7 (a1)
By detecting the amount of change in (a2), the amount of displacement of the displacement electrode 8 in the Z direction can be measured.

FIG. 3 shows another embodiment of the present invention. FIG. 3A shows an electrode structure in this embodiment.
The cathode electrode 2, the insulating layer 3, the gate electrode 4, and the emitter 5 are the same as those shown in FIG. In this embodiment, the displacement electrode 8 configured to move in the direction of the arrow in the figure by external force or vibration is divided into two parts a1 and a2 and used as an anode electrode. This is different from that shown in FIG.

That is, in the embodiment shown in FIG. 1, the change in the electron trajectory due to the displacement of the displacement electrode 8 is detected by the change in the current density distribution at the anode electrode 7. In this embodiment, The change in the electron trajectory caused by the displacement electrode 8 is detected by the current flowing through the displacement electrode itself. Reference numeral 9 denotes a Nesa film provided above and set to the ground level (0 [V]), so that electrons passing through the position of the displacement electrode 8 are attracted to the displacement electrode 8 again. ing.

The displacement electrode (anode) in this embodiment
FIG. 2 shows the distribution ratio (a1 / a2) characteristics with respect to the moving distance of FIG.
(B) of FIG. As is clear from this figure, the anode voltage applied to the displacement electrode (anode) 8 is 150 [V].
When the distance is increased, the distribution ratio increases as the moving distance of the displacement electrode (anode) increases, and it can be seen that the acceleration can be measured by measuring the distribution ratio as in the case of FIG.

Also, in this embodiment, when the displacement electrode (anode) 8 moves in the Z direction (vertical direction in the figure), as shown in the analysis results of the electron trajectory shown in FIG. The amount of the emitted electrons captured by the displacement electrode (anode) 8 varies. That is, when the displacement electrode 8 moves upward, the displacement electrode (anode)
The number of electrons captured by the electrode 8 increases, and the anode current flowing through the displacement electrode (anode) 8 (the divided displacement electrode (anode) 8 (a1) and the displacement electrode (anode) 8)
(The sum of the anode currents flowing in (a2)) increases. On the other hand, when the displacement electrode (anode) 8 moves downward, the number of electrons captured by the displacement electrode (anode) 8 decreases, and the anode current flowing through the displacement electrode (anode) 8 increases. Therefore, by detecting the amount of change in the anode current (the sum of the anode currents flowing through the divided displacement electrode (anode) 8 (a1) and the displacement electrode (anode) 8 (a2)), the displacement electrode 8 The displacement amount in the Z direction, that is, the component of acceleration in the Z direction can also be measured.

FIG. 4 shows still another embodiment of the present invention.
In this figure, a cathode electrode 2, an insulating layer 3, a gate electrode 4, an emitter 5, and a displacement electrode (deflection electrode) 8 are the same as those shown in FIG. 1A, and a detailed description thereof will be omitted. . In this embodiment, the insulating layer 3 is further disposed on the gate electrode 4, and the focusing electrode 15 is provided thereon. Also, the anode electrode 7 is shown in FIG.
A material having a predetermined resistance value is not used as the anode electrode 7 as in the case of the above.

In this configuration, when a predetermined potential is supplied to each of the cathode electrode 2, the gate electrode 4, the focusing electrode 15, the displacement electrode (deflection electrode) 8, and the anode electrode 7, electrons emitted from the emitter 5 are emitted. The flow is made into a sharp beam by the focusing electrode 15 and reaches the anode electrode 7. The arrived electrons pass through the anode electrode 7 and flow to the anode terminal A. At this time, since the anode electrode 7 is formed of a material having a predetermined resistance value, a resistance r proportional to the distance from the end of the anode electrode 7 to the position where the electrons have arrived is connected in series with the anode current path. Has been inserted.

When a force or vibration is applied from the outside and the displacement electrode (deflection electrode) 8 is displaced relative to the other electrodes, the direction of the electron beam emitted from the emitter 5 is changed. The position of the electron beam reaching the anode electrode 7 is changed by moving the electrode 8. As a result, the distance from the end of the anode electrode 7 to the arrival point of the electron current changes, so that the value of the resistor r inserted in the anode current path changes, and the anode current changes. Therefore, by detecting the anode current, the displacement of the displacement electrode (deflection electrode) 8, that is, the acceleration can be measured.

An example of a configuration embodying the above-described acceleration sensor of the present invention will be described. FIG. 5 is a perspective view showing the inside of one configuration example of the acceleration sensor of the present invention. In FIG. 5, 1 is a substrate made of silicon or the like, 2 is a cathode electrode provided on the substrate 1, 4 is a gate electrode provided on the cathode electrode 2 via an insulating layer (not shown), and 5 is
A cone-shaped emitter is provided in the opening provided in the gate electrode 4 and the insulating layer and provided on the cathode electrode 2. Reference numeral 11 denotes an insulating layer formed on the outer peripheral portion of the cathode electrode 2. Reference numeral 12 denotes a frame portion, 13 denotes a pantograph-shaped spring portion which is elastically deformed, and 8 denotes a displacement electrode.

In this configuration example, the frame portion 12 is separated on the way, and the two portions 8 (a1) and 8 (a2) of the displacement electrode 8 are electrically separated. I have. And the frame part 12, the spring part 13
The displacement electrode 8 is integrally formed, and the frame portion 12 is arranged on the insulating layer 11. Although not shown in this figure, a second substrate is provided on the upper portion, and the inside of the sensor is kept in a vacuum state. Then, a lead electrode is provided from each electrode to the outside of the sensor.

The pantograph-shaped spring portion 13 is the same as that used in a microactuator of a micromachine, and can be manufactured by a photolithography method or the like.

AA 'of the acceleration sensor shown in FIG.
Sectional views are shown in FIGS. 6 (a) and 6 (b). FIG. 6A is a sectional view when the displacement electrode 8 is used as an anode as shown in FIG. In this figure, a substrate 1, a cathode electrode 2, a gate electrode 4, an emitter 5, a displacement electrode 8, an insulating layer 11, a frame portion 12, and a spring portion 13 are the same as those described above, and therefore detailed description thereof is omitted. I do. Reference numeral 3 denotes an insulating layer provided on the cathode electrode 2, on which a gate electrode 4 is formed. Reference numeral 14 denotes a sealing member arranged on the frame portion 12, and on the sealing member 14,
The second substrate 15 provided with the Nesa film 9 is arranged. The sealing member 14 keeps the inside of the apparatus in a vacuum state.

In the acceleration sensor configured as described above, when a force or vibration is applied from the outside of the sensor, the spring portion 13 is deformed by the inertial force, and the displacement electrode (anode) 8 supported by the spring portion 13 and other components Relative displacement occurs between the first and second portions. As described above, this allows the respective displacement electrodes (anodes) 8 (a1) and 8 (a)
A difference occurs in the anode current flowing in 2), and the acceleration (X-direction component) can be obtained by measuring the distribution ratio of the anode current. Also, as mentioned above,
Each displacement electrode (anode) 8 (a1) and 8
By measuring the sum of the anode currents flowing through (a2), the Z-direction component of the acceleration can also be measured.

FIG. 6B is a cross-sectional view of the acceleration sensor when the displacement electrode 8 is used as a deflection electrode as shown in FIG. However, in this case, the frame portion 12 in FIG. 5 is not separated in the middle, and the two portions 8 (a1) and 8 (a) of the displacement electrode 8 are not separated.
2) is assumed to be electrically connected. In this figure, the same members as those in FIG. 6A are denoted by the same reference numerals, and detailed description thereof will be omitted. In the case of this figure, the second substrate 15 is different from the one shown in FIG. 6A in that the anode electrode 7 divided into an a1 portion and an a2 portion is provided. I have.

In the acceleration sensor configured as described above, when a force or vibration is applied from outside the sensor, the displacement electrode (deflection electrode) 8 supported by the spring portion 13 moves as described above. The direction of the electrons emitted from the anode electrode 7 is changed, and the portions a1 and a2 of the anode electrode 7 are changed.
A difference occurs in the anode current flowing to the portion. By measuring this, the acceleration (X direction) can be measured. Also, by measuring the current value of the sum of the anode currents flowing through the portions a1 and a2 of the anode electrode 7,
It can measure the Z-direction component of the acceleration.

As described above, the acceleration sensor of the present invention
Since it is provided on the substrate 1 such as silicon, a plurality of acceleration sensors can be provided on a single substrate. In this case, each acceleration sensor is connected to the displacement electrode 8.
Is formed so that the directions of the displacements are different, it is possible to detect the components of the acceleration in both the X and Y directions or the components in the three directions of XYZ. Further, an electronic circuit can be formed on the same substrate, and peripheral circuits such as an A / D conversion circuit and an amplifier circuit for processing an anode current output from the acceleration sensor or other electronic circuits can be formed on the same substrate. It can be formed into an acceleration sensor module and can be very easy to handle.

In the above description, the acceleration in one dimension (X direction) or in the X direction and the Z direction is measured by a single element. However, according to the present invention, one element is measured. It is also possible to simultaneously measure accelerations in the X direction and the Y direction, or in three directions of X, Y and Z. FIGS. 7A and 7B show an internal configuration example of such an acceleration sensor.

In FIG. 7A, the substrate 1, the cathode electrode 2, the insulating layer 11, and the frame portion 12 are the same as those described above, so that detailed description thereof will be omitted. Further, as shown in the figure, a field emission portion including a gate electrode 4 and an emitter 5 is provided at the center of the substrate 1. The displacement electrode 8 has four parts (a1, a
2, a3, a4), and each is connected to each side of the frame 12 by the corresponding spring 13. And each side of the frame part 12 is electrically separated. That is, FIG. 7A shows a case where the displacement electrode 8 is used as an anode electrode. Although not shown, a second substrate 15 is provided above the frame portion 12 via a sealing member 14 as in FIG. 6A, and the inside of this sensor is in a vacuum state. It is made to be held.

In the acceleration sensor configured as described above, when a force or vibration is applied from the outside, the components in the X direction are displaced electrodes (anodes) 8 (a2) and 8 (a4).
And the component in the Y direction can be detected by the distribution ratio of each anode current between the displacement electrode (anode) 8 (a
It can be detected by the distribution ratio of each anode current in 1) and 8 (a3). Further, by detecting a change in the total current of the anode currents flowing through the divided displacement electrodes (anodes) 8 (a1) to 8 (a4), Z
Directional components can be detected. Therefore, with this configuration, three-dimensional acceleration can be detected with one element.

Next, the embodiment shown in FIG. 7B will be described. In this figure, a substrate 1, a cathode electrode 2, a gate electrode 4, an emitter 5, an insulating layer 11, and a frame portion 12 are the same as those described above, and thus detailed description thereof will be omitted. In the embodiment shown in this figure, the displacement electrode 8 is not divided and is supported on each side of the frame portion 12 by a plurality of spring portions 13. In other words, the one shown in this figure uses the displacement electrode 8 as a deflection electrode, and the second substrate (not shown) provided above has an anode electrode 7 divided into four with the center right above the emitter 5 as the center. It has been formed.

In the acceleration sensor thus configured, when a force or vibration is applied from the outside, the displacement electrode (deflection electrode) 8 supported by the spring portion 13 is displaced in a three-dimensional space. As described above, the XY components of the displacement can be measured by comparing the anode currents flowing through the corresponding portions of the four divided anode electrodes (not shown). The measurement can be performed by obtaining the sum of the anode currents flowing through the four divided anode electrodes. Therefore, also in this embodiment, it is possible to obtain three-dimensional acceleration with one element.

In each example shown in FIG. 7, the displacement electrode 8 or the anode electrode 7 is described as being divided into four parts. However, the present invention is not limited to this. It is possible to measure acceleration in a plane. Also, as described above, peripheral circuits such as an A / D converter circuit and an amplifier circuit for processing the anode current output from the acceleration sensor and other electronic circuits are formed on the same substrate to form a module, thereby achieving a small size. And can be easily handled.

Thus, an electronic circuit is formed on the same substrate.
To process the output from the acceleration sensor.
Peripheral circuits such as A / D conversion circuits and amplification circuits
Sensor module with multiple electronic circuits formed on the same substrate
Rules.

In each of the above embodiments, the displacement electrode is
Although provided separately, the gate electrode itself is supported by a spring part.
It is also possible to have a structure to hold. In addition, each of the above
In the embodiment, the outer shape of the acceleration sensor is square.
However, it is not limited to this,
Shape.

[0044]

According to the present invention, semiconductor fine processing technology
Field electron-emitting device manufactured in a vacuum and operating in a vacuum.
Small, lightweight, high precision, and very stable
Acceleration sensor having improved characteristics can be provided.
You. Also, three-dimensional acceleration is detected by a single element.
be able to. Furthermore, an electronic circuit is formed on the same substrate.
Can reduce the size of the entire device.
To provide an acceleration sensor that is easy to handle
be able to.

Although the displacement electrodes are separately provided in each of the above embodiments, a structure in which the gate electrode itself is supported by a spring portion is also possible. Further, in each of the above-described embodiments, the external shape of the acceleration sensor is a square. However, the present invention is not limited to this.

[0046]

According to the present invention, since a field electron emitting device manufactured by a semiconductor fine processing technique and operated in a vacuum is used, it has a small and light weight, high accuracy, and very stable characteristics. An acceleration sensor can be provided. In addition, a three-dimensional acceleration can be detected with a single element. Furthermore, since an electronic circuit can be formed on the same substrate, the entire device can be reduced in size and an acceleration sensor that can be easily handled can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an embodiment of an acceleration sensor according to the present invention.

FIG. 2 is a diagram for explaining an operation state in one embodiment of the acceleration sensor of the present invention.

FIG. 3 is a diagram for explaining another embodiment of the acceleration sensor of the present invention.

FIG. 4 is a view for explaining another embodiment of the acceleration sensor of the present invention.

FIG. 5 is a perspective view for explaining the internal structure of an embodiment of the acceleration sensor of the present invention.

FIG. 6 is a cross-sectional view for explaining an internal structure of an embodiment of the acceleration sensor according to the present invention.

FIG. 7 is a perspective view for explaining an internal structure of another embodiment of the acceleration sensor of the present invention.

FIG. 8 is a view for explaining a field emission device .

Continuation of the front page (56) References JP-A-7-63780 (JP, A) JP-A-6-11517 (JP, A) JP-A-6-288843 (JP, A) JP-A-6-34652 (JP) JP-A-6-235733 (JP, A) JP-A-63-186114 (JP, A) JP-A-7-174780 (JP, A) JP-A-8-5651 (JP, A) 7-198741 (JP, A) JP-A-8-54409 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01P 15/08-15/18 H01L 29/84

Claims (4)

(57) [Claims] 1. An emitter formed in a cone shape, a gate electrode portion provided with an opening near an upper end of the cone-shaped emitter, and an opening emitted from the emitter, A displacement electrode portion disposed in a direction substantially orthogonal to a traveling direction of a passing electron flow, and a displacement electrode portion disposed in a vacuum container; and the displacement electrode portion is three-dimensionally moved by a spring portion deformable in the vacuum container. An acceleration sensor, which is swingably supported by and is divided into four or more regions, and measures acceleration based on an electron flow flowing through the divided regions. 2. A method according to claim 1, characterized in that the focusing electrode is provided in the middle between the displacement electrode and the gate electrode portion
Serial mounting acceleration sensor. 3. An emitter formed in a cone shape, a gate electrode portion provided with an opening in proximity to a point above a tip of the cone-shaped emitter, A displacement electrode portion arranged in a direction substantially perpendicular to the traveling direction of the passing electron flow, the displacement electrode portion allowing the electron flow to pass through an opening provided at a substantially central portion, and an opening of the displacement electrode portion And an anode electrode portion arranged to supplement the electron flow passing through the vacuum container, and the displacement electrode portion is swingable in a three-dimensional direction by a spring portion deformable in the vacuum container. An acceleration sensor which is supported and measures acceleration based on an electron flow flowing in each of the anode electrode portions divided into four or more regions. 4. according to any one of claims 1 to 3 in which electronic circuits such as A / D conversion circuit or the amplifier circuit is characterized in that provided on the substrate on which the emitter is formed Acceleration sensor.