JP2001074470A - Gyroscope and input device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gyroscope for making a device smaller, improve detection sensitivity, and lower the drive voltage, etc. SOLUTION: This gyroscope 1 comprises a tuning fork 2, provided with three legs 9 and support part 10, upper and lower glass substrates 7 and 8 between which the tuning fork 2 is held, a driving movable electrode 3 provided on the upper surfaces of the legs 9, a driving fixed electrode 4 provided on the lower surface of the upper glass substrate 7 as to face it, six detecting movable electrodes 5, which are provided on the upper surface of the tip part of legs 9 connected in parallel, and six detecting fixed electrode 6, which are provided on the lower surface of the upper side glass substrate 7 to face it, connected in parallel.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gyroscope and an input device using the gyroscope, and more particularly to a gyroscope of a type for detecting displacement of a tuning fork leg when an angular velocity is input by a change in capacitance, and an input device using the gyroscope. It is about.

[0002]

2. Description of the Related Art A gyroscope using a tuning fork formed of a material such as silicon having conductivity has been known. This type of gyroscope vibrates the tuning fork leg in one direction, and generates vibration in the direction perpendicular to the vibration direction caused by Coriolis force when an angular velocity with the longitudinal axis of the leg as the central axis is input during vibration. It is to detect. Since the magnitude of the vibration generated by the Coriolis force corresponds to the magnitude of the angular velocity, this gyro sensor can be used as an angular velocity sensor, and can be applied to, for example, a coordinate input device of a personal computer.

FIG. 15 is a diagram showing a configuration of a tuning fork which is a main part of a conventional gyroscope. As shown in this figure, the tuning fork 100 of this example has three legs 101 and each leg 10.
1 and a supporting portion 102 for connecting the base end sides thereof, and is made of conductive silicon. Tuning fork 100
Are fixed on a substrate 103 by a support portion 102, and a driving electrode (not shown) is provided at a position below each leg 101.
Are provided respectively. Therefore, each leg 101 is caused by electrostatic attraction generated when a voltage is applied to the driving electrode.
Are configured to vibrate in the vertical direction.

In this gyroscope, when an angular velocity whose rotation axis is the longitudinal direction of the leg 101 is input during the vertical vibration, horizontal vibration is generated. The horizontal vibration is applied to both sides of each leg 101. Detection is performed by a pair of detection electrodes 104 arranged. That is, when the leg 101 is displaced in the horizontal direction and the distance between the detection electrode 104 disposed on one side of the leg 101 and the leg 101 is reduced, the detection electrode 104 disposed on the other side and the leg 101 The distance is widened, and two sets of capacitances formed by the detection electrodes 104 and the legs 101 change. From the change in the capacitance, the magnitude of the input angular velocity can be detected.

[0005]

In the gyroscope having the above-described structure, the detection electrodes 104 are arranged on both sides of each leg 101, so that the distance between the legs 101 (hereinafter referred to as the gap between the legs). Could not be made too narrow. That is, assuming that the width of the detection electrode 104 is x ₁ , the distance between the detection electrode 104 and the leg 101, and the distance between the detection electrodes 104 is x ₂ , the inter-leg gap G is G = 2 × ₁ + 3 × ₂ . Due to the processing limits of x ₁ and x ₂ in silicon processing using a conventional semiconductor device manufacturing technology, there is a limit in reducing the gap G between legs.

On the other hand, it has been found that when the gap G between legs is reduced in a three-legged tuning fork, the "Q value" which is a performance index indicating the magnitude of resonance of this type of device is increased. If the Q value can be increased, in addition to improving the detection sensitivity of the angular velocity, the conversion efficiency of electric energy input to the device into vibration energy is improved, so that the drive voltage can be reduced.

However, as described above, if the gap between the legs can be reduced, the size of the device can be reduced and the detection sensitivity can be improved.
Although it is expected that various advantages, such as a reduction in driving voltage, can be obtained, the conventional gyroscope cannot be realized due to a limitation in reducing a gap between legs.

The present invention has been made in order to solve the above-mentioned problems, and provides a high-quality, low-cost gyroscope which can obtain the above-mentioned various advantages, and an input device using the gyroscope. With the goal.

[0009]

In order to achieve the above object, a gyroscope according to the present invention comprises a vibrating reed forming a tuning fork, a base material opposed to the vibrating reed, and driving the vibrating reed. Driving means and a plurality of detection means provided on a plane parallel to the displacement detection direction of the tip of the vibrating reed, each having a width equal to or greater than the maximum amplitude in the displacement detecting direction of the vibrating reed, and connected in parallel with each other Movable electrode, and the plurality of detection movable electrodes are disposed on the base member so as to face the plurality of detection movable electrodes so as to form a capacitance between the plurality of detection movable electrodes. It has a width equal to or greater than the maximum amplitude, and has a plurality of fixed electrodes for detection connected in parallel with each other.

The detection principle of the gyroscope of the present invention is to detect the vibration of the vibrating piece of the tuning fork (corresponding to the above-mentioned "leg") by a change in capacitance, as in the prior art. Usually, capacity C
Is represented by C = ε · (S / d) (1) (ε: dielectric constant of dielectric, S: area of electrode, d: gap between electrodes). However, the conventional gyroscope detects a change in the distance between the leg and the detection electrode during vibration, that is, a change in capacitance due to a change in the gap d between the electrodes in the above equation (1). The gyroscope is different in that a change in the area of the detection electrodes facing each other during vibration, that is, a change in capacitance due to a change in the electrode area S in the above equation (1) is detected.

That is, the gyroscope of the present invention comprises:
On the vibrating reed side, a plurality of detection movable electrodes each having a width not less than the maximum amplitude in the displacement detecting direction of the vibrating reed and being connected in parallel to each other are provided on a plane parallel to the displacement detecting direction of the tip of the vibrating reed. On the other hand, on the base material side, a plurality of fixed electrodes for detection are arranged in opposition to the plurality of movable electrodes for detection, each having a width equal to or greater than the maximum amplitude in the direction of detecting the displacement of the resonator element, and connected in parallel with each other. The provision of this is the largest feature of the configuration.

With this configuration, when an angular velocity whose rotation axis is the longitudinal direction of the vibrating reed is input in a state where the vibrating reed of the tuning fork is vibrated by the driving means, a direction orthogonal to the vibrating direction is generated by Coriolis force. Vibration occurs. At this time, the movable electrode for detection on the vibrating piece side and the fixed electrode for detection on the base material side face each other, and the facing area of the movable electrode for detection and the fixed electrode for detection changes with the vibration of the vibrating piece. Therefore, a capacitance change occurs. The angular velocity can be detected by detecting this change in capacitance. The reason that the width of each detection electrode is equal to or greater than the maximum amplitude in the displacement detection direction of the vibrating reed is that if the width of each detection electrode is smaller than the maximum amplitude of the vibrating reed, the vibrating reed has a large angular velocity. When the vibrating reed vibrates to the maximum, a state occurs in which the movable electrode for detection on the vibrating reed and the fixed electrode for detection on the substrate side do not face each other,
This is because capacitance detection becomes impossible. The "amplitude" referred to here is, as described as the "amplitude in the displacement detection direction", the amplitude of the vibration generated by the Coriolis force when the angular velocity is input, not the amplitude of the vibration by the driving means.

That is, in the gyroscope of the present invention,
When the base end of the resonator element is supported on an arbitrary substrate, a fixed detection electrode may be provided on the substrate so as to face the movable electrode for detection of the resonator element. There is no need to provide a detection electrode between them. As a result, the gap between the legs can be reduced to the processing limit of the material forming the tuning fork, for example, silicon, so that the Q value can be increased, the detection sensitivity can be improved, and the drive voltage can be reduced. it can. Of course, it is also possible to reduce the size of the device.

As the driving means, for example, a driving electrode may be provided on the vibrating piece side and the base material side so as to face each other. In this case, it is preferable that the driving electrodes are formed so as to extend in the direction in which the respective vibrating bars extend, and the electrodes are preferably separated from each other in order to prevent generation of parasitic capacitance between the driving electrodes and the detection electrodes. If a parasitic capacitance is generated between the driving electrode and the detection electrode, when detecting the angular velocity and detecting a change in capacitance generated between the driving electrode and the detection electrode, the parasitic capacitance is also detected. The noise component causes a problem that the S / N ratio decreases. However, if the driving electrode and the detection electrode are arranged apart from each other, such a problem is prevented from occurring. The movable electrode for detection can be provided on the upper or lower surface of the vibrating reed of the tuning fork. In this case, the detection capacity can be increased, and the electrodes can be easily formed. Further, the movable electrode for detection can be provided on the end face in the extending direction of the resonator element. In this case, the detection fixed electrode can be formed in the same process as the tuning fork, and interference between the detection fixed electrode and the driving means can be reduced.

When the vibrating reed is made of a conductive material,
It is preferable that the plurality of movable electrodes for detection are provided via an insulating film formed at least at a distal end portion of the resonator element.

The positional relationship between each of the movable electrodes for detection and the fixed electrodes for detection is such that the ends of the movable electrodes for detection and the fixed electrodes for detection in the direction of detecting the displacement of the vibrating bar are determined by the displacement of the vibrating bar. It is desirable to dispose them at a distance greater than the maximum amplitude in the detection direction.

The reason is that, in general, when a vibrating reed receives an angular velocity with its longitudinal direction as a rotation axis, the direction perpendicular to the driving direction depends on whether the direction of the angular velocity is clockwise or counterclockwise. The direction of the vibration of the vibrating reed changes in. Therefore, if the movable electrodes for detection and the fixed electrodes for detection are arranged so as to be shifted from each other, when the vibrating piece is displaced in any one direction, the facing area between the movable electrodes for detection and the fixed electrodes for detection increases, and the capacitance is increased. If the vibrating reed is displaced in the direction opposite to the previous direction, the facing area of each movable electrode for detection and each fixed electrode for detection is reduced,
The capacitance will change in a decreasing direction. Therefore, since the direction of the angular velocity can be detected by observing the sign of the amount of change in the capacitance, it is preferable to dispose each movable electrode for detection and each fixed electrode for detection in a staggered manner. In other words, if the ends of the movable electrodes for detection and the fixed electrodes for detection are arranged to be aligned with each other, the facing area between the movable electrodes for detection and the fixed electrodes for detection is set even if the vibrating bar is displaced in any direction. Changes only in the direction in which the angular velocity decreases, the absolute value of the angular velocity can be detected but the direction of the angular velocity cannot be detected. In addition, there is also a problem that it is difficult to align the ends of the movable electrodes for detection and the fixed electrodes for detection in terms of manufacturing.

An input device according to the present invention uses the gyroscope according to the present invention. By using the gyroscope of the present invention, a small device such as a coordinate input device of a personal computer can be realized.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is an exploded perspective view showing the entire configuration of the gyroscope according to the present embodiment, FIG. 2 is a plan view thereof, and FIG.
FIG. 4 is a cross-sectional view taken along line III-III, FIG. 4 is a cross-sectional view taken along line IV-IV in FIG. 2 (an enlarged view showing one leg), and FIG. 5 is a process cross-sectional view showing a method for manufacturing a gyroscope. Symbol 2 in the figure
Is a tuning fork, 3 is a movable electrode for driving, 4 is a fixed electrode for driving, 5
Is a movable electrode for detection, 6 is a fixed electrode for detection, 7 is an upper glass substrate (base material), and 8 is a lower glass substrate.

As shown in FIGS. 1 and 2, the gyroscope 1 of the present embodiment has a three-leg type having three legs 9 (vibrating pieces) and a supporting portion 10 connecting these base ends. Tuning fork 2 is used. A frame 11 is provided around the tuning fork 2, and the tuning fork 2 and the frame 11 are
Originally, it is formed from one silicon substrate having a thickness of about 200 μm and having conductivity. As shown in FIG. 3, the frame portion 11 is sandwiched and fixed between the upper glass substrate 7 and the lower glass substrate 8, and the two glass substrates 7, 8 are fixed.
Of the inner surface of the tuning fork 2 are recessed portions 7a and 8a having a depth of about 10 μm,
By forming a gap of about 10 μm between each of the glass substrates 7 and 8 and the tuning fork 2, each leg 9 of the tuning fork 2 is in a state of being suspended in the air, and can vibrate.

As shown in FIG. 1 and FIG. 2, one driving movable electrode 3 extends in the longitudinal direction of each leg 9 at a position on the base end side of the upper surface of each leg 9. It is provided as follows. Although not shown in FIG. 1 to make the drawing easier to see, the drive movable electrode 3 is, as shown in FIG. 3, an insulating film 12 made of a silicon oxide film or the like having a thickness of about 500 nm formed on a silicon substrate. Is formed through.

On the other hand, at the position on the lower surface of the upper glass substrate 7 facing the movable electrode 3 for driving, one fixed electrode 4 for driving is provided for each leg 9 so as to extend in the longitudinal direction of the leg 9. Is provided. The driving movable electrode 3 and the driving fixed electrode 4 are made of an Al (aluminum) film having a thickness of about 300 nm,
Wirings 13 and 14 for supplying a drive signal to these electrodes 3 and 4 are formed of a material such as a Cr (chromium) film and a Pt (platinum) / Ti (titanium) film.
And is integrally formed by an aluminum film or a chromium film of the same layer as the above.

Further, six movable movable electrodes 5 for each leg 9 are provided at positions on the upper surface of each leg 9 closer to the distal end of the leg 9 than the position where the movable movable electrode 3 is formed. 9 are provided so as to extend in the longitudinal direction. These six movable electrodes 5 for detection are made of an aluminum film or a chromium film having a thickness of about 300 nm similarly to the driving electrodes, and are formed via an insulating film 12 made of a silicon oxide film or the like on a silicon substrate. I have. Further, these six movable electrodes 5 for detection are used.
Are connected in parallel with each other, and a wiring 15 for extracting a detection signal is formed.

On the other hand, at a position closer to the distal end of the leg 9 than the formation position of the driving fixed electrode 4 on the lower surface of the upper glass substrate 7, each leg 9 is opposed to the detection movable electrode 5. Each of the fixed electrodes for detection 6 is provided. Like the movable electrode 5 for detection, these six fixed electrodes 6 for detection are also connected in parallel to each other, and the wiring 1 for extracting a detection signal is provided.
6 are formed.

As shown in FIG. 4, the movable electrode 5 for detection on each leg 9 and the fixed electrode 6 for detection on the upper glass substrate 7 are arranged to face each other. The electrodes 6 are not completely opposed to each other so that the ends of the legs 9 in the displacement detection direction of the electrodes 6 are aligned with each other.
Are displaced from each other by a distance equal to or greater than the maximum amplitude in the displacement detection direction of the leg 9.
In addition, the width W1 of each detection movable electrode 5 and the width W2 of each detection fixed electrode 6 are set to dimensions larger than the maximum amplitude of the leg 9.

Here, an example of the dimensions of each part will be described. The width W of one leg 9 is 200 μm, and the width W of each movable electrode 5 for detection.
1, the width W2 of each fixed electrode 6 for detection is 20 μm, the gap G1 between the movable electrodes 5 for detection and the gap G2 between the fixed electrodes 6 for detection are both 10 μm, the end of the movable electrode 5 for detection and the fixed electrode for detection. The shift amount Z at the end of No. 6 is 5 μm.
The maximum amplitude of the leg 9 in the displacement detection direction is set to 1 μm.

Further, the function of the gyroscope 1 is not particularly necessary, and is necessary for the convenience of manufacturing described later.
On the inner surface side of the upper glass substrate 7 and the inner surface side of the lower glass substrate 8 other than the area where the driving fixed electrode 4 and the detection fixed electrode 6 are provided, the driving fixed electrode 4 and the detection fixed electrode 6 The same potential pattern made of the same aluminum film or chromium film is provided.

Next, an example of a method for manufacturing the gyroscope 1 having the above configuration will be described. As shown in FIG. 5A, a silicon substrate 17 is prepared, and a thermal oxidation method, TEOS-CVD
A silicon oxide film 18 is formed on the upper surface of the silicon substrate 17 using a method such as a method, and the silicon oxide film 18 is patterned by a known photolithography technique so as to be formed in a region other than a portion serving as the frame portion 11 connected to the upper glass substrate 7. The silicon oxide film 18 is left. This silicon oxide film 18 functions as the insulating film 12 for electrically insulating the conductive silicon from the electrodes formed thereon.

Next, as shown in FIG. 5B, a film thickness of 3 is formed over the entire upper surface of the silicon substrate 17 including the silicon oxide film 18.
An aluminum film or a chromium film having a thickness of about 00 nm is sputtered and then patterned by a well-known photolithography technique to form the driving movable electrode 3 and the detection movable electrode 5 at predetermined positions on the upper surface of the silicon substrate 17.

Although not shown, two glass substrates are separately prepared, a chromium film is sputtered on the surface, a resist pattern is formed, and the chromium film is etched using the resist pattern as a mask. Next, using the resist pattern and the chromium film as a mask, the surface of the glass substrate is etched with hydrofluoric acid to form a recess having a depth of about 10 μm in a region corresponding to the position of the tuning fork on the glass substrate. After that, the resist pattern and the chrome pattern are removed. Next, for one glass substrate, a film thickness of 300 n
An aluminum film or a chromium film of about m is sputtered over the entire surface and then patterned using a well-known photolithography technique to form a fixed electrode 4 for driving, a fixed electrode 6 for detection, and the same potential pattern. The substrate is referred to as an upper glass substrate 7. Similarly, with respect to another glass substrate, an aluminum film or a chromium film is sputtered on the entire surface and then patterned to form the same potential pattern, thereby obtaining a lower glass substrate 8.

Next, as shown in FIG. 5C, the lower surface of the silicon substrate 17 and the lower glass substrate 8 are bonded by using an anodic bonding method. At this time, a portion of the silicon substrate 17 which will be the frame 11 later is bonded. In the anodic bonding method, a silicon substrate and a glass can be bonded by applying a positive potential to the silicon substrate and a negative potential to the glass substrate. In a portion where the silicon substrate 17 becomes the tuning fork 2, a gap between the silicon substrate 17 and the surface of the lower glass substrate 8 is formed. Since it is only about 10 μm, when the silicon substrate 17 is bent by electrostatic attraction during anodic bonding and comes into contact with the lower glass substrate 8, this portion is also bonded, and the vibrating tuning fork 2 cannot be formed. Therefore, the surface of the lower glass substrate 8 is set to the same potential as the silicon substrate 17 in order to prevent a portion that should not be bonded to the lower glass substrate 8 from being bonded. The potential pattern is used. The same applies to the upper glass substrate 7.

Next, as shown in FIG. 5D, a resist pattern 19 is formed on the surface of the silicon substrate 17. On this occasion,
The planar shape of the resist pattern 19 is a shape of a portion where silicon is left, such as the tuning fork 2 and the frame portion 11 as shown in FIG. Using the resist pattern 19 as a mask, etching that penetrates the silicon substrate 17 is performed using anisotropic etching such as reactive ion etching. This allows
The tuning fork 2 and the frame portion 11 are formed, and the portion of the tuning fork 2 is suspended above the lower glass substrate 8. After that, when the resist pattern 19 is removed, the shape shown in FIG. 5E is obtained.

Next, the upper surface of the silicon substrate 17 bonded to the lower glass substrate 8 and the upper glass substrate 7 are bonded by using an anodic bonding method. At this time, as shown in FIG. 3, the frame 11 of the silicon substrate 17 is joined to the upper glass substrate 7. Through the above steps, the gyroscope 1 of the present embodiment is completed.

When the gyroscope 1 of the present embodiment is used, an oscillator as a drive source is connected between the wiring 13 of the movable driving electrode 3 and the wiring 14 of the fixed driving electrode 4 and detection is performed. A capacitance detector is connected between the wiring 15 of the movable electrode 5 for use and the wiring 16 of the fixed electrode 6 for detection, and the tuning fork 2 is grounded. Driving movable electrode 3 by driving oscillator
When a voltage having a frequency of about several kHz is applied between the driving fixed electrodes 4, each leg 9 of the tuning fork 2 vibrates in the vertical direction. In this state, when an angular velocity whose rotation axis is the longitudinal direction of the leg 9 is input, a horizontal vibration corresponding to the magnitude of the input angular velocity is generated. At this time, the movable electrode 5 for detection of each leg 9 of the tuning fork 2 and the fixed electrode 6 for detection of the upper glass substrate 7 are in an opposed state, and the movable electrode 5 for detection and the movable electrode 5 for detection are caused by the horizontal vibration of the leg 9. Since the facing area of the fixed electrode 6 changes, a capacitance change occurs. The magnitude of the angular velocity can be detected by detecting the change in the capacitance with the capacitance detector.

Further, in the case of the present embodiment, as shown in FIG. 4, the ends of the detection movable electrode 5 and the detection fixed electrode 6 which face each other are displaced from each other. When the leg 9 is displaced rightward (in the direction indicated by the arrow A) with respect to the glass substrates 7 and 8, each movable electrode 5 for detection
And the fixed area for each detection fixed electrode 6 increases, and the capacitance changes in a direction to increase. When the leg 9 is displaced leftward (in the direction indicated by the arrow B) with respect to the glass substrates 7 and 8, the facing area between each detection movable electrode 5 and each detection fixed electrode 6 is reduced, and the capacitance is reduced. It changes in a decreasing direction. Therefore, the direction of the angular velocity can also be detected by detecting whether the amount of change in the capacitance is positive or negative.

Therefore, in the gyroscope 1 of the present embodiment, it is not necessary to provide a detection electrode between the legs unlike the conventional gyroscope. As a result, the gap between the legs can be reduced to near the processing limit of the silicon substrate, for example, to about several tens of μm, and the Q value can be increased. For example, in a gyroscope having a leg width of 200 μm, the gap between legs is 300 μm to 400 μm.
If it is about m, the Q value is about 1000, but if the gap between the legs is reduced to about several tens of μm, the Q value can be increased to about 2000, which is about double. By increasing the Q value, it is possible to improve the detection sensitivity as an angular velocity sensor and reduce the drive voltage. Further, the size of the device can be reduced.

The present applicant has already filed a gyroscope of another configuration in order to achieve the object of the present invention.
The gyroscope of the present invention is an improved version of the gyroscope of the prior application, and has the following advantages over the gyroscope of the previous application. FIG. 13 is an exploded perspective view showing the entire configuration of the gyroscope of the prior application, and FIG. 14 is a cross-sectional view taken along line XIV-XIV of FIG. 13 and 14, the same reference numerals are given to the same components as those of the gyroscope of the present embodiment shown in FIGS. 1 to 4, and the detailed description will be omitted.

The gyroscope 21 shown in FIGS. 13 and 14 is different from the gyroscope 1 of the above embodiment in that the lower part of the upper glass substrate 7
Each of the fixed electrodes for detection 6 is provided. And
Since the leg 9 itself made of conductive silicon functions as an electrode, each leg 9 has neither a driving electrode nor a detecting electrode.

In the case of the gyroscope 1 of the present embodiment, one movable leg 5 is provided with six movable electrodes 5 for detection and one fixed electrode 6 for detection.
And the fixed electrodes for detection 6 are connected in parallel with each other. FIG. 9 shows this in an equivalent circuit diagram. Further, the capacitances formed by the electrode pairs of the movable electrode 5 for detection and the fixed electrode 6 for detection are represented by C ₁ , C ₂ , C ₃ , C ₄ , respectively.
And C _5, C _6. If the angular velocity is not input to the leg 9 and the displacement per leg is C _dt1 when the displacement is 0 (initial state) without Coriolis force _acting , C _dt1 = C ₁ + C ₂ + C ₃ + C ₄ + C ₅ + C ₆ (2) Next, if an arbitrary angular velocity is input to the leg 9 and the total capacity when displacement occurs due to the _{action of} Coriolis force is C _dt2 , C _dt2 = (C ₁ + ΔC ₁ ) + (C ₂ + ΔC ₂₎ ) + ... + (C ₆ + ΔC ₆ ) ... (3) (where ΔC ₁ , ΔC ₂ ,..., ΔC ₆ are the amount of capacitance change in each capacitance). When this is modified, the following expression (4) is obtained.

(Equation 1) More generally, when n detection electrodes are provided for one leg, the following equation (5) is obtained.

(Equation 2) As an example of a specific capacitance value, C _dt1 is about 1 pF, Δ
C _i is set to about 0.01～0.1PF.

In the case of the gyroscope 21 shown in FIGS. 13 and 14, since two detection electrodes 6 are provided for one leg 9, n in Expression (5) is 2
For example, the capacity change amount per leg is 0.02 to
It is about 0.2 pF. On the other hand, in the case of the gyroscope 1 of the present embodiment, n in the equation (5) is 6, and for example, the amount of change in capacitance per leg is 0.06-0.
It is about 6 pF. Therefore, even if the leg 9 receives the angular velocity of the same magnitude and the displacement of the same magnitude occurs, the gyroscope 1 of the present embodiment changes the capacity three times as much as the gyroscope 21 of the already applied patent, in other words, , 3
Double sensitivity can be obtained. Therefore, if n detection electrodes are provided for one leg 9, it is possible to obtain (n / 2) times higher sensitivity than the gyroscope 21 of the already applied patent. Thus, the gyroscope 1 of the present embodiment
According to the method, the detection sensitivity can be further improved.

The gyroscope 1 of the present embodiment
Since the tuning fork 2 is sandwiched between the two glass substrates 7 and 8, the portion of the tuning fork 2 is protected by the glass substrates 7 and 8, making it easy to handle. Further, since the structure is such that dust does not easily enter the tuning fork 2, disturbance is suppressed, and sensor accuracy can be improved. Also,
The structure can also perform vacuum sealing, and according to this, the Q value can be further improved.

[Second Embodiment] Hereinafter, a second embodiment of the present invention will be described.
The embodiment will be described with reference to FIG. FIG. 6 is an enlarged view showing an electrode configuration for one leg of the gyroscope of the present embodiment. The basic configuration of the gyroscope of the present embodiment is completely the same as that of the first embodiment, and the point that the gyroscope of the present embodiment is different from the first embodiment is that the configuration of the electrode per one leg is different. Only. Below,
Only the different parts will be described with reference to FIG. 6 in which the same components as those in FIG. 4 are denoted by the same reference numerals, and description of the common parts will be omitted.

In the first embodiment, the detection movable electrode 5 and the detection fixed electrode 6 are provided only on the upper surface of the leg 9 and the lower surface of the upper glass substrate 7, respectively. In the scope 23, similar electrodes are provided on the upper surface of the lower glass substrate 8 and the lower surface of the legs 9. That is, the position of each leg 9 near the tip of the lower surface of each leg 9 is
, Six movable electrodes for detection 5 are provided so as to extend in the longitudinal direction of the leg 9. These six movable electrodes for detection 5 have a film thickness of 300 like the electrodes on the upper surface side of the leg 9.
made of aluminum film or chromium film of about nm,
It is formed via an insulating film 12 made of a silicon oxide film or the like. The six movable electrodes 5 for detection are connected in parallel with each other, and furthermore, a wiring (not shown) for extracting a detection signal is formed.

On the other hand, on the upper surface of the lower glass substrate 8, six fixed detection electrodes 6 are provided for each leg 9 in correspondence with the movable movable electrode 5. The drive electrodes 5 and 6 on the upper surface of the leg 9 and the movable electrodes 5 and 6 on the lower surface of the leg 9 are both connected to the end of the movable electrode 5 for drive and the end of the fixed electrode 6 for drive. They are shifted by a distance equal to or greater than the maximum amplitude in the detection direction.

Also in the gyroscope 23 of the present embodiment, the Q value can be increased by eliminating the detection electrodes between the legs 9, thereby improving the detection sensitivity as an angular velocity sensor, reducing the drive voltage, and improving the device. Can be downsized,
Thus, the same effect as in the first embodiment can be obtained.

Further, regarding the detection sensitivity, in the case of the present embodiment, all the six capacitors formed on the upper surface side of the leg 9 and the six capacitors formed on the lower surface side of the leg 9 are all connected in parallel. Thus, twelve capacitors are formed for one leg, and the gyroscope 1 of the first embodiment is formed.
The sensitivity can be improved by a factor of two, and by a factor of six compared to the gyroscope 21 of the patent application shown in FIGS.

[Third Embodiment] Hereinafter, a third embodiment of the present invention will be described.
Will be described with reference to FIGS. 7 and 8. FIG. In the claims, "... provided on a plane parallel to the displacement detection direction of the tip of the vibrating reed ... a plurality of movable electrodes for detection ..." is described in the first and second embodiments. In the embodiment, the “plane parallel to the displacement detection direction” that the vibrating reed (leg) has
Among them, the example in which the movable electrode for detection is formed on the upper surface or the lower surface of the leg is described. On the other hand, in the third embodiment,
An example in which a detection movable electrode is formed on the tip end surface of a leg will be described.
FIG. 7 is an exploded perspective view showing the entire configuration of the gyroscope according to the present embodiment, and FIG. 8 is a plan view thereof. This embodiment also differs from the first and second embodiments only in the configuration of the detection electrodes. Therefore, FIGS. 7 and 8
1, the same components as those in FIGS. 1 and 2 are denoted by the same reference numerals, and detailed description of the common portions will be omitted.

The gyroscope 25 of the embodiment is
As shown in FIGS. 7 and 8, one detection electrode installation unit 26 is provided for each leg 9 so as to face the front end surface 9 a in the direction in which each leg 9 extends. 8 is fixed. The areas of the opposing surfaces of the leg 9 and the detection electrode installation section 26 are substantially the same. In addition to the tuning fork 2 and the frame portion 11, the detection electrode installation portion 26 is originally formed from a single silicon substrate having a thickness of about 200 μm and having conductivity.

On the tip surface 9a of each leg 9, six detection movable electrodes 27 are provided for each leg 9 so as to extend in a direction perpendicular to the displacement detection direction of the leg 9, that is, in a vertical direction. It is provided in. These six movable electrodes 27 for detection
Is formed on an end face 9a of each leg 9 via an insulating film 12 made of a silicon oxide film or the like. Further, these six detection movable electrodes 27 are connected in parallel with each other. On the other hand, a surface 26 facing the tip end surface 9a of the leg 9 of the detection electrode
On the “a”, six detection fixed electrodes 28 are provided for each leg 9 via the insulating film 12 so as to extend in the vertical direction, corresponding to the detection movable electrodes 27. Each fixed electrode 28 for detection is arranged opposite to each movable electrode 27 for detection,
The six fixed electrodes for detection 28 are connected in parallel with each other. The configuration of the driving electrode is the same as in the first and second embodiments.

In the case of the gyroscope 25 of the present embodiment, since the vibration direction (displacement detection direction) of the leg 9 due to the Coriolis force at the time of inputting the angular velocity is in the vertical direction on the paper of FIG. The opposing area between the movable electrode 27 for detection and the fixed electrode for detection 28 changes, causing a change in capacitance. By detecting this change in capacitance, the magnitude of the angular velocity can be detected.

Also in the gyroscope 25 of the present embodiment, the Q value can be increased by eliminating the detection electrodes between the legs 9, thereby improving the detection sensitivity as an angular velocity sensor, reducing the drive voltage, and improving the device. Can be downsized,
The same effects as those of the first and second embodiments can be obtained.

[Fourth Embodiment] Hereinafter, a fourth embodiment of the present invention will be described.
Will be described with reference to FIGS. 10 to 12. FIG. This embodiment is an example of an input device using the gyroscope of the first to third embodiments, and more specifically, an example applied to a pen-type mouse which is a coordinate input device of a personal computer.

The pen-shaped mouse 30 of the present embodiment is similar to the one shown in FIG.
As shown in FIG. 0, a gyroscope 32 as shown in the first to third embodiments is provided inside a pen-shaped case 31.
a and 32b are accommodated. As shown in FIG. 11, when the pen-shaped mouse 30 is viewed from above (when viewed from the direction of the arrow A in FIG. 10), the two gyroscopes 32a and 32b serve as legs of the tuning forks of the gyroscopes 32a and 32b. Are arranged such that their extending directions are orthogonal. Also,
A drive detection circuit 33 for driving each of the gyroscopes 32a and 32b and detecting a rotation angle is provided. In addition, while the battery 34 is housed in the case 31,
Two switches 35 corresponding to a general mouse switch
a, 35b, a switch 36 of the mouse body, and the like.

The user holds the pen-shaped mouse 30,
By moving the pen tip in a desired direction, a cursor or the like on the screen of the personal computer can be moved in accordance with the moving direction of the pen tip. In other words, the pen tip is positioned on page 3 in FIG.
7, the gyroscope 32b detects the rotation angle θ1. When the gyroscope 32 is moved along the Y-axis direction of the drawing 37, the gyroscope 32a rotates the rotation angle θ.
2 is detected. When it is moved in any other direction, the combination of the rotation angles θ1 and θ2 is obtained. Therefore, the personal computer receives signals corresponding to the rotation angle θ1 and the rotation angle θ2 from the pen-shaped mouse 30, and as shown in FIG. The cursor 39 is moved by a distance corresponding to the rotation angles θ1 and θ2 in correspondence with the X ′ axis and the Y ′ axis. In this way, the pen-shaped mouse 30
Can realize the same operation as a general mouse using an optical encoder or the like.

The gyroscope 3 of the present invention used here
Since 2a and 32b have characteristics of small size, low drive voltage, and high sensitivity, they can be suitably used for a small coordinate input device such as the pen mouse 30 of the present embodiment. Further, the present invention can be applied to general input devices for detecting angular velocity, such as navigation and head-mounted displays.

The technical scope of the present invention is not limited to the above-described embodiment, and various changes can be made without departing from the spirit of the present invention. For example, in the gyroscope according to the above-described embodiment, the example in which the driving electrodes are provided on the upper glass substrate is shown, but the driving electrodes may be provided on the lower glass substrate. In addition, not only one glass substrate but also both glass substrates may be provided. On the other hand, as for the detection electrodes, the number of detection electrodes provided for each leg may be arbitrarily set. However, from the viewpoint of improving sensitivity, it is desirable to increase the number as long as processing is possible. The detection electrodes may be formed on three different legs, for example, on the upper surface, the lower surface, and the upper surface. Further, in the above-described embodiment, an example is shown in which a three-leg type tuning fork is used. However, the number of legs can be changed, and one leg may be used.

Further, instead of sandwiching the tuning fork made of silicon between two glass substrates, a configuration may be adopted in which there is no upper glass substrate. In this case, the gyroscope has a simpler structure. Further, considering the bonding by the anodic bonding method, the compatibility between silicon and glass is good, but a glass substrate formed by forming glass on the surface of an arbitrary substrate can be used instead. It is also possible to use carbon instead of silicon as the material of the tuning fork. Others
Specific descriptions of materials, dimensions, and the like of various constituent members are not limited to the above-described embodiments, and can be appropriately changed.

[0058]

As described above in detail, in the gyroscope of the present invention, there is no need to provide a detection electrode between the legs of the tuning fork as in the prior art.
The value can be increased, the detection sensitivity can be improved, the driving voltage can be reduced, and the device can be downsized. By using the gyroscope, a small device such as a coordinate input device of a personal computer can be realized.

[Brief description of the drawings]

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

FIG. 2 is a plan view of the same.

FIG. 3 is a side sectional view taken along the line III-III of FIG. 2;

FIG. 4 is a side sectional view taken along the line VI-VI of FIG. 2 and is an enlarged view showing an electrode configuration per leg.

FIG. 5 is a process sectional view sequentially showing a method of manufacturing the gyroscope.

FIG. 6 is an enlarged view showing an electrode configuration for one leg in the gyroscope according to the second embodiment of the present invention.

FIG. 7 is an exploded perspective view showing a gyroscope according to a third embodiment of the present invention.

FIG. 8 is a plan view of the same.

FIG. 9 is an equivalent circuit diagram showing a configuration of a capacitance of the gyroscope according to the embodiment.

FIG. 10 is a perspective view showing a pen mouse according to a fourth embodiment of the present invention.

FIG. 11 is a plan view showing the arrangement of two gyroscopes used in the pen-type mouse.

FIG. 12 is a front view showing a personal computer screen on which an operation is performed using a pen mouse.

FIG. 13 is an exploded perspective view showing an example of a gyroscope filed by the present applicant.

14 is a side sectional view taken along the line XIV-XIV in FIG.

FIG. 15 is a perspective view showing an example of a conventional gyroscope.

[Explanation of symbols]

1, 2, 23, 25, 32a, 32b Gyroscope 2 Tuning fork 3 Driving movable electrode 4 Driving fixed electrode 5, 27 Detection movable electrode 6, 28 Detection fixed electrode 7 Upper glass substrate (base material) 8 Lower side Glass substrate 9 Leg (vibrating piece) 10 Support part 11 Frame part 12 Insulating film 17 Silicon substrate 26 Detection electrode installation part 30 Pen-type mouse (input device)

Continued on the front page (72) Eiji Shinohara 1-7, Yutani-Otsuka-cho, Ota-ku, Tokyo Alps Electric Co., Ltd. (72) Inventor Masayoshi Esashi 1-11-9 Yagiyama Minami 1-chome, Taishiro-ku, Sendai, Miyagi F-term (Reference) 2F105 AA10 BB02 BB13 CC01 CC04 CD03 CD05 4M112 AA02 BA07 CA26 CA31 CA36 DA03 DA09 DA18 EA03 EA06 EA13

Claims (4)

[Claims] 1. A vibrating reed forming a tuning fork, a base material opposed to the vibrating reed, a driving means for driving the vibrating reed, and a vibrating reed on a surface parallel to a displacement detection direction of a tip of the vibrating reed. A plurality of movable electrodes for detection, each having a width equal to or greater than the maximum amplitude in the displacement detection direction of the vibrating piece and connected in parallel with each other, and forming a capacitance between the plurality of movable electrodes for detection. A plurality of fixed electrodes for detection are provided on the base member so as to be opposed to the plurality of movable electrodes for detection, each of which has a width equal to or greater than a maximum amplitude in a direction of detecting displacement of the vibrating piece and are connected in parallel with each other. And a gyroscope having: 2. The vibrating reed is made of a conductive material, and the plurality of movable electrodes for detection are provided via an insulating film formed at least at a tip end of the vibrating reed. Gyroscope as described. 3. An end of each of the movable electrodes for detection and a fixed electrode for detection in the displacement detection direction of the vibrating reed is displaced from each other by a distance equal to or greater than the maximum amplitude in the displacement detection direction of the vibrating reed. The gyroscope according to claim 1, wherein: 4. An input device using the gyroscope according to any one of claims 1 to 3.