JP2000180176A - Vibration-type angular velocity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce air resistance received by a mass constituting a vibration- type angular velocity sensor during displacement, improve detection sensitivity and reduce a size. SOLUTION: The vibration-type angular velocity sensor includes, on a substrate 10, a mass 11, a beam 14 for supporting the mass 11, driving electrodes 15, 16 for driving the mass 11, and detection parts 11f, 26 for detecting a displacement amount when the driven mass 11 is displaced by angular velocity. The mass 11 is placed at the center of the substrate 10, and the beam 14 is formed in an L-shape wherein it extends horizontally from above and below the mass 11 and further is bent toward the center of the substrate 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration-type angular velocity sensor which is capable of reducing the air resistance applied to a mass constituting a vibration-type angular velocity sensor when it is displaced, improves the detection sensitivity, and can be downsized. .

[0002]

2. Description of the Related Art FIGS. 5A and 5B show a first conventional example. FIG. 5A is a plan view showing the vibration type angular velocity sensor 1 with the case removed, and reference numeral 10 denotes an insulating substrate, 11 denotes an opening hole 11a, and comb-shaped electrodes 11b and 11 on the side.
c is a conductive flat plate-shaped mass part, one end of which is fixed to the substrate 10 by the fixing part 13 and the other end is the mass part 1
Beams 15 and 16 which are formed integrally with each other and extend linearly in the vertical direction in the drawing, have one end fixed to the substrate 10 and the other end interposed between the comb electrodes 11b and 11c alternately.
a, a fixed drive electrode having 16a. Here, the comb-shaped electrodes 11b and 11c cooperate with the mass parts 11b and 11c, and together with the fixed comb-shaped electrodes 15a and 16a, the driving unit 17,
18 are formed.

FIG. 5B is a cross-sectional view taken along the line AA ′ of FIG. 5A. Reference numeral 19 denotes an insulating case which covers the mass unit 11, the driving units 17, 18 and the fixing unit 13. The substrate 10 and the case 19 are provided with detection electrodes 20 and 21 for detecting when the mass portion 11 is displaced in the Z-axis direction. As shown in FIG. 5B, the mass portion 11 and the comb electrodes 15a and 16a are formed so as to float from the substrate 10, and although not shown, the comb electrodes 11b and 11c also float from the substrate 10. Is formed.

FIGS. 6A and 6B are views showing a second conventional example. In the figure, portions corresponding to those of the first conventional example are denoted by the same reference numerals. FIG. 6A is a plan view showing the vibration type angular velocity sensor 2 when the case is removed, where 10 is an insulating substrate, 11 is an opening 11a, and the comb-shaped electrode 1 is on the side.
1b, 11c, a conductive flat plate-shaped mass portion having comb-shaped electrodes 11d, 11e formed on the upper and lower sides.
3 is a beam which is fixed to the substrate 10 and the other end is integrally formed with the mass portion 11. Fixed drive electrodes having 15a, 16a, 2
2, 23 are comb-shaped electrodes 22a, 22a, one end of which is fixed to the substrate 10 and the other end is interposed between the comb-shaped electrodes 11d, 11e alternately.
It is a fixed detection electrode having 3a. Here, the comb-shaped electrodes 11b, 11c, 11d, and 11e cooperate with the mass unit 11, and the comb-shaped electrodes 11b and 11c are fixed comb-shaped electrodes 15a,
Drive units 17 and 18 are formed together with the comb-shaped electrode 11a.
d and 11e are Y together with the fixed comb electrodes 22a and 23a.
Detectors 24 and 25 for detecting axial displacement are formed.

FIG. 5B is a cross-sectional view taken along the line AA ′ of FIG. 5A, and 19 is a mass unit 11, driving units 17 and 18, and a detecting unit 2.
4 and 25 and a case that covers the fixing portion 13. Substrate 1
0, the case 19 is provided with detection electrodes 20 and 21 for detecting when the mass portion 11 is displaced in the Z-axis direction. FIG.
As shown in (B), the mass part 11 and the comb-shaped electrode 15
a and 16a are formed so as to float from the substrate 10, and although not shown, the comb-shaped electrodes 11b, 11c, 11d, 11
Similarly, e is formed so as to float from the substrate 10.

[0006]

However, in the first prior art, as shown in FIG. 5A, since the beams 14 are formed in a straight line, a space is formed on both sides of the beams 14. As a result, the area of the mass part cannot be made large with respect to the area of the substrate 10, and since the gas escape hole 11a is provided for countermeasures against the viscous resistance of air, the mass of the mass part 11 is further reduced and the sensitivity of the sensor is reduced. And the problem that it is not suitable for miniaturization.

[0007] Further, as shown in FIG.
Is limited by the gap size between the case 19 and the substrate 10, and the vibrator cannot be made thick. Further, since the mass portion 11 comes into contact with the substrate 10 on the surface, a sticking phenomenon called sticking occurs, and In some cases, it becomes impossible, and there is a problem that the sensitivity and stability of the sensor are not suitable.

In the second conventional example, FIG.
As shown in (A) and (B), when the comb-shaped electrodes 11b, 11c, 11d, and 11e are provided on four sides of the square mass portion 11,
The area of the mass portion 11 cannot be made large with respect to the area of the substrate 10, and a gas escape hole 11a for countermeasures against viscous resistance of air.
Is provided, the mass of the mass part 11 is further reduced, and there is a problem that the sensitivity and the size of the sensor are not suitable.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a vibration-type angular velocity sensor capable of reducing the air resistance applied to a mass part constituting the vibration-type angular velocity sensor when it is displaced, improving the detection sensitivity, and miniaturizing the vibration-type angular velocity sensor. And

[0010]

The object of the present invention is to provide a mass section, a beam supporting the mass section, a driving electrode for driving the mass section, and a driving electrode for driving the mass section on a substrate. In a vibration-type angular velocity sensor including a detecting unit that detects a displacement amount of a mass unit according to an angular velocity, the mass unit is disposed at a central portion of the substrate, and the beams are disposed above and below the mass unit. , And can be achieved by forming an L-shape extending horizontally from the substrate and bent toward the center of the substrate.

Further, on the substrate, a mass, a beam supporting the mass, a driving electrode for driving the mass, and the mass in a driven state are displaced by an angular velocity, and the amount of displacement is In the vibration type angular velocity sensor having a detecting portion for detecting the mass portion, the driving electrode, and a case covering the detecting portion, the detecting portion has an opening hole in the mass portion, This can be achieved by forming the detection electrode disposed in the hole fixed to the substrate.

A mass part made of a silicon material, a beam supporting the mass part, a driving electrode for driving the mass part, and the mass part in a driven state are displaced by an angular velocity on the substrate. Has a detection unit for detecting the amount of displacement,
In the vibration-type angular velocity sensor including a case that covers the mass, the driving electrode, and the detection unit, a step is formed on the substrate and the case so that a distance corresponding to the mass between the substrate and the case is increased. Can be achieved.

Further, on the substrate, a mass part, a beam supporting the mass part, a driving electrode for driving the mass part, and the mass part in a driven state are displaced by an angular velocity, and the displacement amount In the vibration type angular velocity sensor having a detecting portion for detecting the mass portion, the driving electrode, and a case covering the detecting portion, an opening for air escape is provided in a portion of the case corresponding to the mass portion. This can be achieved by forming a hole.

Further, on the substrate, a mass part, a beam supporting the mass part, a driving electrode for driving the mass part, and the mass part in a driven state are displaced by an angular velocity, and the displacement amount In the vibration-type angular velocity sensor including a mass section, a driving electrode, and a case covering the detection section, the detection section includes the mass section and an electrode provided on the case. This can be achieved by forming an opening for air escape in a portion of the case excluding the electrodes.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments shown in the drawings. FIG. 1 (A), (B)
FIG. 1 is a schematic plan view showing a first embodiment of a vibration type angular velocity sensor according to the present invention, in which a case is removed and a sensor is viewed from above, and a cross-sectional view taken along line AA ′ of FIG. In the figure, portions corresponding to the first and second conventional examples are denoted by the same reference numerals.

A mass portion 11 made of a silicon material and an L-shaped beam 14 that can be deformed in three axial directions (X, Y, Z) in accordance with the displacement of the mass portion 11 are provided. The L-shaped beam 14 extends left and right from the top and bottom in the drawing of the mass portion 11 and has a shape that is bent toward the upper and lower central portions of the substrate 10 at an intermediate portion. By forming the beam 14 into an L-shape, the mass 11
However, as shown in the drawing, it is formed in an elongated shape having a large area extending upward and downward.

The driving parts 17 and 18 are formed on the comb-shaped electrodes 11b and 11c formed on the sides of the mass part 11 and the fixed driving electrodes 15 and 16, and are alternately interposed between the comb-shaped electrodes 11b and 11c. And the comb electrodes 15a and 15b.

Reference numeral 26 denotes a detection electrode. As will be described later, when the mass part 11 is displaced in the direction B in FIG. 1A, the distance between the edge 11f of the opening 11a of the mass part 11 and the detection electrode 26 changes, and the distance is changed accordingly. A detection unit that detects a change in the capacitance value is configured.

As shown in FIG. 1B, the comb-shaped electrodes 15a,
16a, mass part 11, and comb-shaped electrodes 11b, 11c, beam part 1 (not shown) formed on mass part 11
Reference numeral 4 denotes a configuration that can be displaced by a physical quantity in a floating state without being fixed on the substrate 10.

The driving electrodes 15 and 16, the detection electrode electrode 26 and the beam 14 which are disposed in the opening 11 a of the mass section 11.
Is fixed to the substrate 10.

As shown in FIG. 1B, steps 27 and 28 are formed between the substrate 10 and the case 19 so that the distance corresponding to the mass portion 11 is increased. This step 27,
By virtue of 28, the thickness of the mass portion 11 can be made large, the viscosity resistance of air can be reduced, and the sensitivity can be improved.
Further, since the distance between the mass portion 11 and the substrate 10 and the case 19 can be increased, it is effective in preventing the above-described sticking.

Next, the operation of this device will be described. The angular velocity is detected by, for example, applying V to each of the outer comb electrodes (11b, 15a) and (11c, 16a) facing each other in the X-axis direction.
When the voltages t + Vdsin (ωt) and Vt−Vdsin (ωt) (Vt: DC bias voltage, Vdsin (ωt): AC voltage for driving) are applied, the comb-shaped electrodes 11b, 1
When the electrostatic force is generated in 1c and the drive frequency is made equal to the resonance frequency in the X-axis direction, the mass unit 11 resonates in the X-axis direction. When an angular velocity (Ωz) is applied around the Z axis in this state, resonance also occurs in the Y axis direction perpendicular to the vibrating X axis by Coriolis force, and the mass portion 11 is displaced in the direction of the arrow B. The magnitude of this vibration is proportional to the angular velocity, and the mass 11
The distance between the edge 11f of the opening hole 11a and the detection electrode 26 changes, resulting in a change in capacitance, and the angular velocity (Ωz) can be detected.

In some cases, the acceleration signal, the angular velocity, and the vibration component are added to the detection signal, and the angular velocity component is H
After the acceleration component is removed by the PF, separation and detection can be performed by synchronous detection at the excitation frequency.

Here, in an angular velocity sensor having a movable mass part having a small mass, a surface force such as a viscous resistance of air has a greater influence on the operation than a body force such as gravity applied to the mass part. I have. Therefore, in order to secure the detectable capacitance when detecting with the capacitance, and to increase the driving force when performing the electrostatic driving, the mass unit 11 and the substrate 1 are used.
Since it is necessary to narrow the gap between the electrodes to 0 (or the case 19), it is necessary to design in consideration of the damping of the gas existing in the gap by the squeeze film.

In addition, it is necessary to provide a configuration for improving the space utilization efficiency and reducing the air resistance of the displaced mass portion 11 in order to reduce the size and increase the sensitivity.

FIGS. 2A and 2B show a second embodiment of the vibration type angular velocity sensor according to the present invention. FIG. 2A is a schematic plan view showing the sensor with the case removed. A
It is a sectional view taken on line -A '. In the figure, parts corresponding to those of the first and second conventional examples and the first embodiment are denoted by the same reference numerals.

The angular velocity of the vibration type sensor 4 is detected by applying a drive voltage to each of the outer comb electrodes (11b, 15a) and (11c, 16a) facing each other in the X-axis direction as in the first embodiment. Then, when an angular velocity (Ωz) is applied around the Z axis, resonance occurs due to the Coriolis force in the Y axis direction, and the mass section 11 is displaced in the arrow C direction. Therefore,
There is no displacement of the mass 11 in the Z-axis direction.

In the present embodiment, the case 19 located in the direction in which no displacement occurs is provided with an opening
Is formed. With this configuration, when the mass unit 11 is displaced in the Y-axis direction, the compressed air escapes from the opening hole 29, and the effect of reducing the viscous resistance of the air of the mass unit 11 is obtained.

FIGS. 3A and 3B show a vibration type angular velocity sensor according to a third embodiment of the present invention. FIG. 3A is a schematic plan view of the sensor with the case removed, and FIG. A
It is a sectional view taken on line -A '. In the figure, parts corresponding to the first and second conventional examples, the first embodiment and the second embodiment are denoted by the same reference numerals.

The angular velocity of the vibration type sensor 5 is detected by detecting the outer comb electrodes (11b, 15a) and (1) facing each other in the X-axis direction.
1c and 16a), when a drive voltage is applied to each of them and an angular velocity (Ωz) is applied around the Y axis, resonance occurs due to the Coriolis force in the Z axis direction, and as shown in FIG. In the direction.

In the present embodiment, the case 19 has a structure in which holes 30 of a similar size are formed in the case 19 in correspondence with the opening holes 11a for the air escape of the mass portion 11. The holes 30 allow escape of gas for measures against the viscous resistance of air to improve detection sensitivity.

FIGS. 4A and 4B show a vibration type angular velocity sensor according to a fourth embodiment of the present invention. FIG. 4A is a schematic plan view of the sensor with the case removed, and FIG. A
It is a sectional view taken on line -A '. In the figure, parts corresponding to those in the first embodiment are denoted by the same reference numerals.

The angular velocity of the vibration type sensor 6 is detected by applying a drive voltage to each of the outer comb electrodes (11b, 15a) and (11c, 16a) facing each other in the X-axis direction as in the first embodiment described above. Then, when an angular velocity (Ωz) is applied around the Z axis, resonance occurs due to the Coriolis force in the Y axis direction, and the mass section 11 is displaced in the direction of arrow E.

In the first embodiment, it has been described that the thickness of the mass portion 11 can be increased by providing steps 28 and 29 in the substrate 10 and the case 19. Only by providing steps 28 and 29 in 19, the gap with the mass portion 11 is widened, the viscous resistance of the air is reduced, and the sensitivity is improved.

[0035]

As described above, according to the present invention, the mass resistance of the vibration type angular velocity sensor is reduced by the air resistance when the displacement occurs, the detection sensitivity is improved, and the size can be reduced. Vibration type angular velocity sensor can be provided.

[Brief description of the drawings]

1A and 1B show a first embodiment of a vibration type angular velocity sensor according to the present invention, wherein FIG. 1A is a plan view and FIG.
FIG. 3 is a sectional view taken along line A ′.

FIGS. 2A and 2B show a second embodiment of a vibration type angular velocity sensor according to the present invention, wherein FIG. 2A is a plan view and FIG.
FIG. 3 is a sectional view taken along line A ′.

3A and 3B show a vibration type angular velocity sensor according to a third embodiment of the present invention, wherein FIG. 3A is a plan view, and FIG. 3B is AA ′ of FIG.
It is a line sectional view.

4A and 4B show a vibration-type angular velocity sensor according to a fourth embodiment of the present invention, wherein FIG. 4A is a plan view and FIG. 4B is a cross-sectional view taken along line AA ′ of FIG.

5A and 5B show a vibration type angular velocity sensor according to a first conventional example, where FIG. 5A is a plan view and FIG. 5B is a sectional view taken along line AA ′ of FIG. 5A.

6A and 6B show a vibration type angular velocity sensor according to a first conventional example, wherein FIG. 6A is a plan view and FIG. 6B is a sectional view taken along line AA ′ of FIG. 6A.

[Explanation of symbols]

 1, 2, 3, 4, 5, 6 Vibration type angular velocity sensor 10 Substrate 11 Mass part 13 Fixed part 14 Beam 15, 16 Fixed drive electrode 17, 18 Drive part 19 Case 20, 21, 22, 23, 26 Detection electrode 24, 25 Detector 27, 28 Step 29, 30 hole

Claims (5)

[Claims] 1. A mass part, a beam supporting the mass part, a driving electrode for driving the mass part, and the mass part in a driven state are displaced by an angular velocity on a substrate, and the displacement amount is In the vibration-type angular velocity sensor provided with a detection unit for detecting the mass, the mass is disposed at the center of the substrate, and the beam extends horizontally from above and below the mass, and further, the center of the substrate A vibration-type angular velocity sensor characterized by being formed in an L-shape bent in a part direction. 2. A mass part, a beam supporting the mass part, a driving electrode for driving the mass part, and the mass part in a driven state are displaced by an angular velocity on a substrate, and the displacement amount is In the vibration type angular velocity sensor having a detecting portion for detecting the mass portion, the driving electrode, and a case covering the detecting portion, the detecting portion has an opening hole in the mass portion, A vibration type angular velocity sensor formed by fixing a detection electrode disposed in a hole to the substrate. 3. A mass part, a beam supporting the mass part, a driving electrode for driving the mass part, and the mass part in a driven state are displaced by an angular velocity on a substrate, and the displacement amount is In the vibration-type angular velocity sensor including the mass part, the driving electrode, and the case covering the detection part, the distance corresponding to the mass part between the substrate and the case increases. Thus, a vibration type angular velocity sensor characterized in that a step is provided on the substrate and the case. 4. A mass part, a beam supporting the mass part, a driving electrode for driving the mass part, and the mass part in a driven state are displaced by an angular velocity on a substrate, and the displacement amount In the vibration type angular velocity sensor having a mass portion, a driving electrode, and a case covering the detection portion, a portion corresponding to the mass portion of the case is provided for air escape. A vibration type angular velocity sensor characterized in that an opening is formed. 5. A mass part, a beam supporting the mass part, a driving electrode for driving the mass part, and the mass part in a driven state are displaced by an angular velocity on a substrate, and the displacement amount is In the vibration-type angular velocity sensor including a mass section, a driving electrode, and a case covering the detection section, the detection section includes the mass section and an electrode provided on the case. And the capacitance change
A vibration type angular velocity sensor characterized in that an opening for air escape is formed in a part of the case other than the electrode.