JP2000321071A - Gyroscope and input device employing it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gyroscope for reducing the size, enhancing the detection sensitivity and lowering the driving voltage of a device. SOLUTION: The gyroscope 1 comprises a tuning fork 2 having a plurality of legs 7 and a supporting part 8 made of a conductive material, upper and lower glass substrates 5, 6 clamping the tuning fork 2, a plurality of driving electrodes 3 coupled capacitively with each leg 7 to drive the plurality of legs 7, and detection electrodes 4 provided in correspondence with respective legs 7 and oppositely to the forward end face 7a thereof in the extending direction.

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. 11 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 has a vibrating reed made of a conductive material and a tuning fork having a support for connecting a base end side of the vibrating reed. And a driving electrode capacitively coupled to the vibrating reed and driving the vibrating reed, and a distal end surface provided corresponding to the vibrating reed so that at least a part thereof faces a distal end surface in a direction in which the vibrating reed extends. It is characterized by having at least one detection electrode per vibrating element for detecting a capacitance formed therebetween.

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 it detects a change in the facing area between the leg and the detection electrode during vibration, that is, a change in capacitance due to a change in the electrode area S in the above equation (1).

That is, the gyroscope of the present invention comprises:
The greatest feature of the configuration is that a detection electrode that forms at least a capacitance between the tip end surface of the vibrating piece and the tip end surface in the direction in which the vibrating piece extends is provided. With this configuration, when a voltage is applied to the driving electrode, each vibrating piece of the tuning fork starts to vibrate, and in this state, when an angular velocity with the longitudinal direction of the vibrating piece as a rotation axis is input, the vibration direction is orthogonal to the vibration direction. A directional vibration occurs. At this time, the tip end surface of the vibrating reed faces the detection electrode, and the area of opposition between the tip end surface of the vibrating reed and the detection electrode changes with the vibration of the vibrating reed, so that a capacitance change occurs. The angular velocity can be detected by detecting this change in capacitance.

Therefore, in the gyroscope of the present invention, it is sufficient to provide the detecting electrode on the extension of the vibrating reed in the longitudinal direction, and it is not necessary to provide the detecting electrode between the legs as in the prior art. As a result, since the gap between the legs can be reduced to the processing limit of the material constituting the tuning fork, for example, silicon, the Q value can be increased,
It is possible to improve the detection sensitivity and reduce the driving voltage.
Of course, it is also possible to reduce the size of the device.

As for the detection electrodes, at least one detection electrode may be provided for each vibrating piece. That is,
When the number of detection electrodes is one, it is only necessary to detect a change in capacitance of one capacitor including one detection electrode and one resonator element. When the number of detection electrodes is two, for example, when the vibrating reed is configured to be driven in the vertical direction, two vibrating pieces are arranged in a horizontal direction such that the two detecting electrodes face the tip surface of one vibrating piece. It should just be arranged. In this case, 2
Two capacitors are composed of one detecting electrode and one vibrating reed. When the capacitance of one capacitor increases when vibrating in the horizontal direction, the capacitance of the other capacitor decreases by the increase in the capacitance. . Therefore, in this configuration, if the difference between the two capacitance changes is detected, a double capacitance change can be obtained even with the same vibration, which is preferable in that the detection sensitivity is improved.

The driving electrode may be formed so as to extend in the extending direction of each vibrating reed, and provided at a position corresponding to each vibrating reed on at least one surface of the tuning fork. In this case, each vibrating piece vibrates in the vertical direction with respect to the tuning fork, and the vibration generated by resonance is in the horizontal direction. However, the gyroscope of the present invention is not limited to the one that drives the vibrating reed in the vertical direction and detects the vibration in the horizontal direction, and drives the vibrating reed in the horizontal direction to detect the vibration in the vertical direction. It is also possible to apply to types.

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.

[0016]

DETAILED 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 a perspective view showing an exploded state of the gyroscope 1 of the present embodiment, FIG. 2 is a plan view, FIG. 3 is a side sectional view, and FIG. 4 is a process sectional view showing a method for manufacturing the gyroscope 1. In the figure, reference numeral 2 denotes a tuning fork, 3 denotes a driving electrode, 4 denotes a detection electrode, 5 denotes an upper glass substrate, and 6 denotes a lower glass substrate.

As shown in FIGS. 1 and 2, the gyroscope 1 of the present embodiment has a tuning fork 2 having three legs 7 (vibrating pieces) and a supporting portion 8 connecting these base ends. Used. One detection electrode 4 is provided so as to face the tip end surface 7a in the direction in which each leg 7 extends. The areas of the opposing surfaces of the leg 7 and the detection electrode 4 are substantially the same. A frame 9 is provided around the tuning fork 2, and the tuning fork 2, the detection electrode 4, and the frame 9 originally have a conductivity of about 200 μm in thickness.
It is formed from two silicon substrates. 1 and 3
As shown in the figure, the frame portion 9 is sandwiched and fixed between the upper glass substrate 5 and the lower glass substrate 6, and the upper and lower portions of the tuning fork 2 among the inner surfaces of the two glass substrates 5, 6. Are concave portions 5a, 6 having a depth of about 10 μm.
a, and a gap of about 10 μm is formed between each of the glass substrates 5 and 6 and the tuning fork 2 so that each leg 7 of the tuning fork 2
Can be vibrated. The detection electrode 4 is fixed to the lower glass substrate 6.

As shown in FIG. 1 and FIG. 2, one driving electrode 3 is provided corresponding to each leg 7 of the tuning fork 2.
As shown in the figure, the upper glass substrate 5 is formed of an aluminum film or a chromium film having a thickness of about 300 nm formed on the lower surface. The drive electrode 3 and the detection electrode 4 are provided with terminals (not shown) for voltage application or extraction, respectively.

Further, the function of the gyroscope 1 is not particularly necessary, and is necessary for the convenience of manufacturing described later. Therefore, although not shown, the area where the driving electrode 3 is provided is actually provided. On the inner surface sides of the other glass substrates 5 and 6, the same potential pattern made of the same aluminum film or chromium film as the driving electrode 3 is provided.

Next, an example of a method for manufacturing the gyroscope 1 having the above configuration will be described. As shown in FIG. 4A, a glass substrate 6 is 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, hydrofluoric acid etching is performed on the surface of the glass substrate 6 to form a concave portion 6 a having a depth of about 10 μm in a region corresponding to the position of the tuning fork 2 on the glass substrate 6. After that, the resist pattern and the chrome pattern are removed. Next, an aluminum film or a chromium film having a thickness of about 300 nm is sputtered over the entire surface, and is then patterned using a well-known photolithography technique to form the same potential pattern 10, thereby forming the lower glass substrate 6. The upper glass substrate 5 is also manufactured in the same manner. In the case of the upper glass substrate 5, the same potential pattern 10 and the driving electrode 3 are simultaneously formed by an aluminum film or a chromium film having a thickness of about 300 nm.

As shown in FIG. 4B, the silicon substrate 1
1 is prepared, and the lower surface of the silicon substrate 11 and the lower glass substrate 6 are bonded by using an anodic bonding method. At this time, a portion of the silicon substrate 11 which will later become the support portion 8 and a portion which becomes the detection electrode 4 will be joined. In the anodic bonding method, a silicon substrate and a glass can be bonded by applying a positive potential to the silicon substrate 11 and a negative potential to the lower glass substrate 6. Since the gap is only about 10 μm, when the silicon substrate 11 is bent by the electrostatic attraction during anodic bonding and comes into contact with the glass substrate 6, this portion is also bonded, and the tuning fork 2 cannot be formed. Therefore, in order to prevent the portion that should not be bonded to the glass substrate 6 from being bonded to the glass substrate 6, the surface of the glass substrate 6 is set to the same potential as the silicon substrate 11 in order to prevent the surface from being bonded to the glass substrate 6. 10 is used.

Next, as shown in FIG. 4C, a resist pattern 12 is formed on the surface of the silicon substrate 11. At this time, the planar shape of the resist pattern 12 is the shape of the portion where silicon is left, such as the tuning fork 2, the frame 9, the detection electrode 4, and the like as shown in FIG. Using the resist pattern 12 as a mask, etching that penetrates the silicon substrate 11 is performed using anisotropic etching such as a reactive ion etching method. As a result, the tuning fork 2, the frame portion 9, and the detection electrode 4 are respectively formed, and the legs 7 of the tuning fork 2 float above the lower glass substrate 6. After that, the resist pattern 12 is removed.

Next, as shown in FIG. 4D, the upper surface of the silicon substrate 11 and the upper glass
Are bonded using an anodic bonding method. At this time, the frame 9 and the support 8 of the silicon substrate 11 are joined to the upper glass substrate 5. Through the above steps, the gyroscope 1 of the present embodiment is completed.

When using the gyroscope 1 of the present embodiment, an oscillator is connected to the driving electrode 3, a capacitance detector is connected to the detecting electrode 4, and the tuning fork 2 is grounded. By driving the oscillator, several k
When a voltage having a frequency of about Hz is applied, each leg 7 of the tuning fork 2
Vibrates vertically. In this state, when an angular velocity whose rotation axis is the longitudinal direction of the leg 7 is input, a horizontal vibration corresponding to the magnitude of the input angular velocity is generated. At this time, the tip surface 7a of each leg 7 of the tuning fork 2 and the detection electrode 4 are in a state of facing each other, and the facing area between the tip surface 7a of the leg 7 and the detection electrode 4 changes with the vibration of the leg 7. Therefore, a capacitance change occurs. The angular velocity can be detected by detecting the change in the capacitance with a capacitance detector.

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 is set close to the processing limit of the silicon substrate, for example, 10 g.
It can be reduced to about 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. In addition, the structure can also perform vacuum sealing, whereby the Q value can be further improved.

The gyroscope 1 of the present embodiment
Since the tuning fork 2 is sandwiched between the two glass substrates 5 and 6, the portion of the tuning fork 2 is protected by the glass substrates 5 and 6 and is 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.

Further, if the tuning fork portion and the detection electrode were formed completely separately and fixed on a substrate, it would be expected that a lot of trouble and time would be required for positioning these components during the manufacturing process. However, in the method of manufacturing the gyroscope 1 according to the present embodiment, since one silicon substrate 11 is originally separated by etching to form the tuning fork 2 portion and the detection electrode 4 portion, the alignment is performed. A gyroscope with high processing accuracy can be manufactured without necessity.

[Second Embodiment] Hereinafter, a second embodiment of the present invention will be described.
Will be described with reference to FIGS. 5 to 7. FIG. FIG. 5 is a perspective view showing a state where the gyroscope 20 of the present embodiment is disassembled, FIG. 6 is a plan view, and FIG. 7 is a side sectional view. The gyroscope 20 of the present embodiment differs from the gyroscope 1 of the first embodiment only in the configuration of the detection electrodes. Therefore, in FIGS. 5 to 7, the same reference numerals are given to the same components as those in FIGS. 1 to 3, and the detailed description will be omitted.

The gyroscope 20 of the present embodiment also
Similar to the gyroscope 1 of the first embodiment, as shown in FIGS. 5 and 6, a tuning fork 2 having three legs 7 (vibrating pieces) and a supporting portion 8 connecting these base ends is provided. Used. However, in the first embodiment, one detection electrode 4 is provided for the distal end surface 7a of each leg 7, whereas in the present embodiment, the detection electrode 4 is provided for the distal end surface 7a of each leg 7. And two detection electrodes 21 are provided. In particular, as shown in FIG. 6, the two detection electrodes 21 for each leg 7 are arranged so as to protrude outside the extension of the side surface of each leg 7.

The other structure is the same as that of the first embodiment. A frame 9 is provided around the tuning fork 2, and the tuning fork 2, the detection electrode 21, and the frame 9 are originally formed of one silicon substrate. Is formed from. As shown in FIG. 7, the frame 9 is sandwiched between the upper glass substrate 5 and the lower glass substrate 9, and 10 μm is provided between each of the glass substrates 5 and 6 and the tuning fork 2.
By forming a gap of about m, each leg 7 of the tuning fork 2 is configured to be able to vibrate. The detection electrodes 21 are fixed to the lower glass substrate 6, and the driving electrodes 3 made of an aluminum film are formed on the lower surface of the upper glass substrate 5, one for each leg 7 of the tuning fork 2.

The gyroscope 20 of the present embodiment can also provide the same effects as those of the first embodiment, such as improvement in detection sensitivity, reduction in drive voltage, and downsizing of a device.

However, in the case of the present embodiment, two capacitors are constituted by two detection electrodes 21 and one leg 7, and when the leg 7 vibrates in the horizontal direction, the capacitance of one capacitor increases. Then, the capacity of the other capacitor is reduced by the increase in the capacity. Therefore, if the difference between the two capacitance changes is detected, a double capacitance change can be obtained even with the same vibration, and the detection sensitivity is improved as compared with the first embodiment.

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

FIG. 8 shows a pen-type mouse 30 according to this embodiment.
As shown in FIG. 7, a gyroscope 32 as described in the first or second embodiment is provided inside a pen-shaped case 31.
a and 32b are accommodated. As shown in FIG. 9, the two gyroscopes 32a and 32b extend in the extending directions of the tuning fork legs of the gyroscopes 32a and 32b when the pen-shaped mouse 30 is viewed from above (the direction of arrow A in FIG. 8). Are arranged to be orthogonal. Further, a drive detection circuit 33 for driving each of the gyroscopes 32a and 32b and detecting a rotation angle is provided. Other, case 31
A battery 34 is accommodated therein, and two switches 35a and 35b corresponding to switches of a general mouse, a switch 36 of a mouse body, and the like are provided.

The user holds the pen 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. That is, the pen tip is moved to
Gyroscope 3 when moved along the X-axis direction of
2b detects the rotation angle θ1 and moves it along the Y-axis direction of the paper 37, and the gyroscope 32a turns the rotation angle θ2.
Is detected. When it is moved in any other direction, the combination of the rotation angles θ1 and θ2 is obtained. Therefore,
On the personal computer side, signals corresponding to the rotation angles θ1 and θ2 are received from the pen-type mouse 30 and, as shown in FIG. Axis, the rotation angle θ corresponding to the Y 'axis
1. The cursor 39 is moved by a distance corresponding to the magnitude of θ2. In this manner, the pen-shaped mouse 30
An operation similar to that of a general mouse using an optical encoder or the like can be realized.

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 embodiment, and various changes can be made without departing from the spirit of the present invention. For example, the gyroscopes of the first and second embodiments have a configuration in which the upper and lower sides of a silicon substrate constituting a tuning fork are sandwiched between two glass substrates. However, if anodic bonding is performed in a vacuum chamber, It is also possible to vacuum seal the space for accommodating the tuning fork. With this configuration, the Q value can be further improved, and a highly efficient device can be realized.

Further, instead of sandwiching the silicon constituting the tuning fork and the detection electrode between the two glass substrates, the drive electrode may be provided on the lower glass substrate and the upper glass substrate may not be provided. In this case, the gyroscope has a simpler structure. Also, considering the bonding by the anodic bonding method, the compatibility between silicon and glass is good. However, as for a glass substrate, a material obtained by fusing glass to the surface of an arbitrary base material can be used instead. It is also possible to use carbon instead of silicon as the material of the tuning fork. In addition, specific descriptions of materials, dimensions, and the like of various constituent members are not limited to the above-described embodiment, and can be appropriately changed.

[0039]

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 in FIG. 2;

FIG. 4 is a process cross-sectional view showing a method of manufacturing the gyroscope step by step.

FIG. 5 is a perspective view showing a gyroscope according to a second embodiment of the present invention.

FIG. 6 is a plan view of the same.

7 is a side sectional view taken along the line VII-VII in FIG. 6;

FIG. 8 is a perspective view showing a pen mouse according to a third embodiment of the present invention.

FIG. 9 is a plan view showing an arrangement of two gyroscopes used in the pen-type mouse.

FIG. 10 is a front view showing a personal computer screen on which an operation is performed using a pen mouse.

FIG. 11 is a perspective view showing an example of a conventional gyroscope.

[Explanation of symbols]

 1, 20, 32a, 32b Gyroscope 2 Tuning fork 3 Driving electrode 4, 21 Detection electrode 5 Upper glass substrate 6 Lower glass substrate 7 Leg (vibrating piece) 8 Support 11 Silicon substrate 30 Pen-type mouse (input device)

Continued on the front page (72) Inventor Masayoshi Esashi 1-11-11 Yagiyama Minami 1-chome, Taihaku-ku, Sendai, Miyagi F-term (reference) 2F105 AA10 BB02 BB13 BB14 BB20 CC01 CC04 CC11 CD03 CD05

Claims (3)

[Claims] 1. A tuning fork comprising a vibrating reed made of a conductive material and a support for connecting a base end side of the vibrating reed, and a drive for driving the vibrating reed capacitively coupled to the vibrating reed. At least one per vibrating bar for detecting a capacitance formed between the electrode and the vibrating bar so that at least a part thereof faces a distal end surface in a direction in which the vibrating bar extends is provided. A gyroscope comprising: a plurality of detection electrodes. 2. The driving electrode according to claim 1, wherein the driving electrode is formed so as to extend in a direction in which the vibrating reed extends, and is provided at a position corresponding to the vibrating reed on at least one surface side of the tuning fork. The gyroscope according to claim 1. 3. An input device using the gyroscope according to claim 1 or 2.