JP2010101727A - Vibrating body package and vibration gyro sensor using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vibration gyro sensor which reduces steep temperature change in a zero point output and which is highly accurate in a wide-ranging environment from low temperature to high and suitable for miniaturization. <P>SOLUTION: In regard to a vibrator package constituted by disposing a vibrator inside a container and sealing it airtightly with a flat-plate-shaped lid, the thickness distribution of the lid is made uneven. The lid is shaped so that the central part thereof is convex, that the central part is concave, that there is one or more projections in portions other than the portion contacting the container, that there is one or more grooves in portions other than the portion contacting the container, or in other ways. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vibration gyro sensor in which a vibration body made of a piezoelectric material such as quartz is disposed in a container made of a substrate such as ceramics and hermetically sealed with a lid body.

  The gyro sensor is used for detecting the rotational angular velocity for the purpose of attitude control of a vehicle-mounted car navigation system, a robot, an aircraft, an automobile, or the like, or camera shake correction. Vibrating gyros are inferior in sensitivity and resolution compared to ring-rate gyros and optical fiber gyros that use light interference, but they have medium-precision performance, a simple structure, a small number of parts, and low cost. The market is expanding for consumer use such as camera rotation detection for navigation angular velocity sensors, handy cameras, still cameras, and digital cameras.

The principle of the vibration gyro sensor is as follows. In general, the Coriolis force Fc generated when a mass point that makes a single vibration rotates is expressed by the following equation.

Fc = 2mvΩ

Here, m is the mass of the vibrating gyroscope, v is the vibrating velocity of the vibrating gyroscope, and Ω is the angular velocity around the Z axis of the vibrating gyroscope. If the mass m and the vibration velocity v are known, the angular velocity Ω can be derived by observing the action of the Coriolis force. In the vibrating gyroscope, the displacement of the vibrating body due to the Coriolis force is detected by the generated charge.

  FIG. 8A is a top view of the conventional vibrating body package 101 and shows the top surface of the lid 102. The lid 102 has a flat plate shape. FIG. 8B is a cross-sectional view taken along the line BB in FIG. 8A and shows the structure of the conventional vibrator package 101. The vibrating body package 101 is configured by hermetically sealing a container 103 made of a substrate such as ceramics, silicon, or glass with a lid 102 made of metal, silicon, or glass. The hermetic sealing is performed by heat sealing using gold tin or solder, anodic bonding, surface activated bonding, or the like. The vibrating body 104 is fixed in the container 103 with an adhesive. A large number of electrode pads are arranged in the container 103 to be electrically connected to the vibrating body 104, and the vibrating body 104 is connected to each electrode pad by wire bonding, GGI, or the like. The electrode pad is electrically connected from inside the container 103 to a pad outside the container 103.

  A specific example of the vibrating body 104 shown in FIG. 8 is the vibrating body 1 shown in a perspective view in FIG. The structure will be described below. The vibrating body 1 is, for example, a tuning fork type composed of a rectangular parallelepiped base 2 and two arms 3a and 3b. A piezoelectric single crystal material such as quartz or a langasite piezoelectric material is used and formed by machining, a wet etching process or a dry etching process.

Driving electrodes 4 a and 4 b are arranged on the surfaces of the arm portions 3 a and 3 b, and a VDD electrode pad 5 a and a VSS electrode pad 5 b are formed on the base portion 2. These pads are connected to a number of electrode pads formed in the container by wires such as Au (gold) and Al (aluminum). Furthermore, an electrode pad formed outside the container and electrically connected to the electrode pad in the container is connected to an integrated circuit such as a power source and an oscillation circuit. By applying different voltages to the drive electrodes 4a and 4b, an electric field is generated inside the vibrating body 1. Since the vibrating body 1 is a piezoelectric material, the vibrating body 1 expands and contracts according to the direction of the electric field generated inside, and the arm portions 3a and 3b bend and vibrate due to the stretching motion. As a result, the arms 3a and 3b are excited to open and close in the Y-axis direction.

  Detection electrodes 6a and 6b are arranged on the arm 3b and connected to detection electrode pads 7a and 7b on the base 2, respectively. When an angular velocity Ω is applied to the vibrating body 1 around the Z axis parallel to the arm portions 3a and 3b, the vibration direction of the arm portions 3a and 3b is changed by the Coriolis force Fc and bends and vibrates in the X axis direction. Signals corresponding to changes in the vibration direction of the arm portions 3a and 3b are output from the detection electrodes 6a and 6b. By measuring these signals, a signal corresponding to the angular velocity Ω can be obtained.

  With the development of mobile communication devices and portable devices, miniaturization, high accuracy, and low cost of components are required. Among them, in recent years, applications for detecting angular velocity Ω in a wide range of environments from low temperature to high temperature are expanding. Therefore, in order to sense vibration gyro sensors with high accuracy in a wide range of temperature environments, there is an increasing demand for temperature stability of zero point output. The zero point output is a signal output from the vibration gyro sensor when the angular velocity Ω is not applied in the Z-axis direction. If the temperature fluctuation of the zero point output is unstable, the zero point output changes even though the angular velocity Ω is not actually applied, and the angular velocity Ω is erroneously recognized.

  As a method for improving the temperature fluctuation of the zero point output, a method of improving the signal output from the vibrating body by an external correction circuit (see, for example, Patent Document 2), and the shape of the wire connecting the vibrating body and the electrode terminal There has been proposed a method (see, for example, Patent Document 3).

JP-A-11-177364 JP 2006-189353 A JP 2003-315047 A

  In each of the above existing methods for improving the temperature fluctuation of the zero point output, the method of improving the signal output from the vibrating body by an external correction circuit requires a large number of circuit elements to form the correction circuit. Therefore, a large mounting area is required. Therefore, it is not suitable for downsizing. Also, with respect to various and steep zero point output temperature fluctuations, the correction range is limited by one type of correction circuit, and it is difficult to sufficiently correct the zero point output temperature fluctuations. In addition, it does not eradicate the cause of the sudden temperature fluctuation of the zero point output, so it is not suitable for a permanent improvement method.

  The method of improvement by the wire shape connecting the vibrating body and the electrode terminal only requires a space for connecting at a short distance, but it is necessary to provide an extra space in the container in order to make the wire a desired shape. I need. Therefore, it is not suitable for downsizing. In addition, due to variations in the frequency of the vibrating body and variations in the wire shape, there may be a sudden temperature fluctuation of zero point output. However, even if a steep change occurs after the container is hermetically sealed with the lid, the wire shape cannot be changed and it is difficult to improve.

  An object of the present invention is to provide a vibration gyro sensor that reduces a steep temperature fluctuation of a zero point output and is highly accurate and suitable for downsizing in a wide range of environments from a low temperature to a high temperature.

  In order to solve the above problems, the present invention provides a vibrating body package in which a vibrating body is disposed inside a container and hermetically sealed with a lid, and the lid has a flat outer surface. Therefore, the thickness distribution is non-uniform.

In addition, the shape of the lid has a convex shape at the central portion, a concave shape at the central portion, a shape having one or more protrusions other than the portion in contact with the container, and one or more other than the portion in contact with the container. It is characterized by a groove.

  ADVANTAGE OF THE INVENTION According to this invention, the vibrating body package which suppresses the vibration coupling | bonding with the cover body which is a cause of the rapid temperature fluctuation of zero point output in the temperature range of -40 to 85 degreeC can be provided.

  In addition, it is possible to provide a vibration gyro sensor that is highly accurate and suitable for downsizing in a wide range of environments from low temperature to high temperature.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 1A is a top view of the vibrating body package 8 according to the first embodiment of the present invention, and shows the top surface of the lid body 9. The lid 9 has a convex shape at the center. FIG. 1B is a sectional view taken along the line BB in FIG. 1A and shows the structure of the vibrating body package 8. The vibrating body package 8 is configured by hermetically sealing a container 10 made of a ceramic substrate with a lid body 9 made of metal. Airtight sealing is performed by gold-tin heat sealing. The vibrating body 11 is fixed in the container with an adhesive. A large number of electrode pads are arranged in the container 10, and each electrode pad is electrically connected to the vibrating body 11. The electrode pad is connected to the integrated circuit to constitute a vibration gyro sensor.

  In the manufacturing method of the vibrator 11, a quartz substrate generally called a Z plate is used. The Z plate is a substrate that is substantially perpendicular to the Z axis in the crystal direction of the crystal, that is, the upper and lower surfaces form an angle of 85 to 95 degrees with respect to the Z axis. Note that the crystallographic Z-axis here is different from the Z-axis of the coordinate system defined in relation to the shape of the vibrator 11.

  A metal film is formed on the quartz substrate, and the outer shape of the vibrating body 11 is formed by photolithography and etching. After removing the metal film by an etching method, an electrode film is formed. In this embodiment, a 0.15 μm thick Au film (upper layer) and a 0.03 μm thick Cr film (lower layer) are formed on a quartz substrate by sputtering, and the film is subjected to photolithography to drive electrodes. Then, a detection electrode is formed.

  The material of the vibrator is not limited to quartz, and piezoelectric single crystals such as lithium tantalate and lithium niobate can be used. Further, it can be formed not only by wet etching but also by dry etching or machining.

  A vibration gyro sensor is configured by electrically connecting the vibration body package 8 and the integrated circuit. FIG. 2 is a schematic diagram of a circuit configuration of the vibration gyro sensor. The vibrating body 11 is, for example, the vibrating body 1 shown in a perspective view in FIG. The oscillation circuit 12 is connected between the VDD electrode pad 5a and the VSS electrode pad 5b. Thereby, bending vibration is performed so that the arm portions 3a and 3b of the vibrating body 1 are opened and closed.

  On the other hand, the detection electrode pads 7 a and 7 b are connected to the differential circuit 13. The differential circuit 13 is configured by an operational amplifier, a resistor, and the like. Further, the output terminal of the differential circuit 13 is connected to the synchronous detection circuit 14. In the synchronous detection circuit 14, the output signal of the differential circuit 13 is detected in synchronization with the signal of the oscillation circuit 12. The output signal of the synchronous detection circuit 14 is converted into a DC signal by the integration circuit 15. Further, the output signal of the integrating circuit 15 is amplified by a DC amplifier circuit.

When the rotational angular velocity Ω is not applied to the vibration gyro sensor, the two arms 3a and 3b of the vibrating body 1 vibrate in the same state with respect to the polarization direction, and thus are output from the detection electrode pads 7a and 7b. The signal is the same. Therefore, no output signal is generated.

  When the rotational angular velocity Ω is applied, the Coriolis force Fc works in the X-axis direction orthogonal to the Y-axis. Therefore, the arms 3a and 3b vibrate in the direction in which the driving force applied in the opening / closing direction and the Coriolis force Fc are combined, and during rotation, when the output from one detection electrode 6a increases, the other detection is performed. The output from the working electrode 6b decreases, or the reverse operation occurs. Therefore, if the difference between the output signals of the detection electrode pads 7a and 7b is obtained by the differential circuit 13, a signal corresponding to the Coriolis force can be obtained. The output signal of the differential circuit 13 is detected by the synchronous detection circuit 14 and amplified by the DC amplification circuit 16.

  Since the level of the output signal from the detection electrode pads 7a and 7b is determined by the magnitude of the displacement of the arm portions 3a and 3b of the vibrating body 1, the level of the output signal increases when a large Coriolis force Fc acts. Therefore, the magnitude of the rotational angular velocity Ω can be detected from the level of the output signal of the DC amplifier circuit 16.

  If the integrated circuit of the vibration gyro sensor is electrically connected to the vibration body, the integrated circuit can be embedded in the vibration package 8 or the container 10 instead of being formed outside the vibration package 8.

  FIG. 3 shows an example of the temperature fluctuation of the zero point output using the conventional vibrating body package 101 of FIG. 8, and a steep temperature fluctuation occurs in the vicinity of 10 ° C.-20 ° C. On the other hand, FIG. 4 shows an example of the temperature fluctuation of the zero point output using the vibrating body package 8 obtained by processing the lid body 9 into a convex shape in the first embodiment. The temperature range is -40 ° C to 85 ° C.

  By processing the central portion of the lid 9 into a convex shape, the resonance frequency of the primary mode of the lid 9 is increased, and vibration coupling with the resonance frequency of the vibrating body 11 (FIG. 2) is suppressed. Therefore, as shown in FIG. 4, the sharp temperature fluctuation of the zero point output is improved and almost disappeared, and a vibration gyro suitable for miniaturization can be provided with high accuracy in a wide range of environments from low temperature to high temperature.

  The convex shape processing of the central portion of the lid body 9 was performed by local deposition technology using silver.

  The method of processing into a convex shape is not limited to the local deposition technique, and various film forming methods such as adhesive coating, solder coating, sputtering, and vapor deposition can be applied.

  The material for forming the convex shape is not limited to silver, but a metal or an insulator having good adhesion to the lid 9 and a large mass is preferable.

(Second Embodiment)
FIG. 5A is a top view of the vibrating body package 17 according to the second embodiment of the present invention, and shows the top surface of the lid 18. The lid 18 has a concave shape at the center. FIG. 5B is a cross-sectional view taken along the line B-B in FIG. The vibrator package 17 is configured by hermetically sealing a container 19 made of a ceramic substrate with a lid 18 made of metal. Hermetic sealing is performed by gold-tin heat sealing. The vibrating body 20 is fixed in the container 19 with an adhesive. A large number of electrode pads are arranged in the container 19 to be electrically connected to the vibrating body 20, and each electrode pad is electrically connected to the vibrating body 20. The electrode pad is connected to the integrated circuit to constitute a vibration gyro sensor.

By processing the central portion of the lid 18 into a concave shape, the resonance frequency of the primary mode of the lid 18 is lowered, and vibration coupling with the resonance frequency of the vibrating body 20 is suppressed. Therefore, the sharp temperature fluctuation of the zero point output is improved, and a vibration gyro suitable for downsizing can be provided with high accuracy in a wide range of environments from low temperature to high temperature.

  The concave shape processing of the center part of the lid 18 was performed using a sandblast method.

  The method of processing into a concave shape is not limited to the sandblasting method, and laser processing, machining, chemical etching, and the like can be applied.

(Third embodiment)
FIG. 6A is a top view of the vibrating body package 21 according to the third embodiment of the present invention, and shows the top surface of the lid body 22. The lid 22 forms one or more protrusions 24 other than the portion in contact with the container 23. 6B is a cross-sectional view taken along the line BB in FIG. 6A and shows the structure of the vibrating body package 21. FIG. The vibrating body package 21 is configured by hermetically sealing a container 23 made of a ceramic substrate with a lid body 22 made of metal. Airtight sealing is performed by gold-tin heat sealing. The vibrating body 25 is fixed in the container 23 with an adhesive. A large number of electrode pads are arranged in the container 23 to be electrically connected to the vibrating body 25, and each electrode pad is electrically connected to the vibrating body 25. The electrode pad is connected to the integrated circuit to constitute a vibration gyro sensor.

  The lid body 22 is formed with one or more protrusions 24 other than the portion in contact with the container 23, whereby the resonance frequency of the primary mode of the lid body 22 is increased and vibration with the resonance frequency of the vibrating body 25 is performed. Binding is suppressed. Therefore, the sharp temperature fluctuation of the zero point output is improved, and a vibration gyro suitable for downsizing can be provided with high accuracy in a wide range of environments from low temperature to high temperature.

  The method of forming one or more protrusions 24 other than the portion in contact with the container 23 on the lid 22 was performed by a local deposition technique using silver.

  The method for forming the protrusion 24 is not limited to the local deposition technique, and various film forming methods such as adhesive coating, solder coating, sputtering, and vapor deposition can be applied.

  The material for forming the protrusions 24 is not limited to silver, but a metal or an insulator having good adhesion to the lid 22 and a large mass is preferable.

(Fourth embodiment)
FIG. 7A is a top view of the vibrating body package 26 according to the fourth embodiment of the present invention, and shows the top surface of the lid 27. The lid 27 forms one or more grooves 29 in addition to the portion in contact with the container 28. FIG. 7B is a cross-sectional view taken along the line BB in FIG. 7A and shows the structure of the vibrating body package 26. The vibrating body package 26 is configured by hermetically sealing a container 28 made of a ceramic substrate with a lid body 27 made of metal. Hermetic sealing is performed by gold-tin heat sealing. The vibrating body 30 is fixed in the container 28 with an adhesive. A large number of electrode pads are arranged in the container 28 to be electrically connected to the vibrating body 30, and each electrode pad is electrically connected to the vibrating body 30. The electrode pad is connected to the integrated circuit to constitute a vibration gyro sensor.

  The lid body 27 is formed with one or more grooves 29 other than the portion in contact with the container 28, thereby lowering the resonance frequency of the primary mode of the lid body 27 and vibration coupling with the resonance frequency of the vibrating body 30. Is suppressed. Further, depending on the formation position of the groove 29, it is possible to suppress the vibration coupling of the lid body 27 with the frequency of the second and third order higher modes. Therefore, the sharp temperature fluctuation of the zero point output is improved, and it is possible to provide a vibration gyro suitable for miniaturization with high accuracy in a wide range of environments from low temperature to high temperature.

  The method of forming one or more grooves 29 other than the portion in contact with the container 28 in the lid 27 was performed by a sandblast method.

  The method of processing the groove 29 is not limited to the sand blast method, and laser processing, machining, chemical etching, and the like can be applied.

  The present invention is not limited to the above configuration, and various modifications can be made without departing from the scope of the claims. For example, in the third embodiment shown in FIG. 6, three equilibrium protrusions 24 are provided on the lid body 22, but a rectangular continuous frame-like projection substantially similar to the outer shape of the lid body 22 is used as the lid body. It is good also to provide inside 22 from the outer peripheral part which is a location which 22 contacts the container 23. The same applies to the groove 29 in the fourth embodiment of FIG.

In the first embodiment of the vibrating body package of the present invention, (a) is a top view and (b) is a cross-sectional view. It is a schematic diagram which shows the circuit structure of the vibration gyro sensor of this invention. It is a figure which shows an example of the temperature fluctuation of the zero point output of the vibration gyro sensor using the conventional vibrating body package. It is a figure which shows an example of the temperature fluctuation of a zero point output of the vibration gyro sensor using the vibrating body package of this invention. In the second embodiment of the vibrating body package of the present invention, (a) is a top view and (b) is a cross-sectional view. In 3rd Embodiment of the vibrating body package of this invention, (a) is a top view, (b) is sectional drawing. In 4th Embodiment of the vibrating body package of this invention, (a) is a top view, (b) is sectional drawing. In the conventional vibrator package, (a) is a top view and (b) is a cross-sectional view. It is a perspective view which shows an example of the vibrating body used for a vibration gyro sensor.

Explanation of symbols

1, 11, 20, 25, 30, 104 Vibration body 2 Base 3a, 3b Arm 4a, 4b Driving electrode 5a VDD electrode pad 5b VSS electrode pad 6a, 6b Detection electrode 7a, 7b Detection electrode pad 8, 17 , 21, 26, 101 Vibration body package 9, 18, 22, 27, 102 Lid
10, 19, 23, 28, 103 Container 12 Oscillation circuit 13 Differential circuit 14 Synchronous detection circuit 15 Integration circuit 16 DC amplification circuit 24 Projection 29 Groove

Claims (7)

In the vibrator package configured by arranging a vibrator inside the container and hermetically sealing with a lid,
The vibrating body package is characterized in that the lid has a non-uniform thickness distribution by making the outer surface non-flat. The vibrator package according to claim 1,
The lid body is a vibrating body package characterized in that a central portion has a convex shape. The vibrator package according to claim 1,
The lid body is a vibrating body package characterized in that a central portion has a concave shape. The vibrator package according to claim 1,
The lid body is formed with one or more protrusions other than a portion in contact with the container. The vibrator package according to claim 1,
The lid body is formed with one or more grooves other than a portion in contact with the container.   6. A vibrating gyro sensor that detects an angular velocity applied from the outside using the vibrating body package according to claim 1. The vibration gyro sensor according to claim 6,
A vibration gyro sensor, wherein the resonance frequency of the lid and the resonance frequency of the vibration body are not vibrationally coupled in a temperature range of -40 ° C to 85 ° C.

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