GB2272054A - Solid state vibrational gyroscope - Google Patents
Solid state vibrational gyroscope Download PDFInfo
- Publication number
- GB2272054A GB2272054A GB9222980A GB9222980A GB2272054A GB 2272054 A GB2272054 A GB 2272054A GB 9222980 A GB9222980 A GB 9222980A GB 9222980 A GB9222980 A GB 9222980A GB 2272054 A GB2272054 A GB 2272054A
- Authority
- GB
- United Kingdom
- Prior art keywords
- circuit board
- printed circuit
- gyroscope
- bell
- resonator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01C—MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY
- G01C19/00—Gyroscopes; Turn-sensitive devices using vibrating masses; Turn-sensitive devices without moving masses; Measuring angular rate using gyroscopic effects
- G01C19/56—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces
- G01C19/567—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode
- G01C19/5691—Turn-sensitive devices using vibrating masses, e.g. vibratory angular rate sensors based on Coriolis forces using the phase shift of a vibration node or antinode of essentially three-dimensional vibrators, e.g. wine glass-type vibrators
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Gyroscopes (AREA)
Abstract
The gyroscope includes a resonator bell 30 attached to a printed circuit board 40 by mounting means 43, which mounting means also provides for electrical connection of conductive tracks on the printed circuit board 40 to electrodes on the resonator bell 30. <IMAGE>
Description
A SOLID STATE VIBRATIONAL GYROSCOPE
This invention relates to a solid state vibrational gyroscope comprising a resonator in the form of a resonator bell, and in particular, but not exclusively, to such gyroscopes wherein the inputs and outputs from the resonator bell are provided by piezoelectric transducers upon a base portion of the resonator bell.
A vibrational gyroscope of the above type is disclosed in UK Patent No. 2164749B. The gyroscope comprises a resonator bell which term for the purposes of this specification, including the claims, means a member having a substantially circular rim susceptible to resonance. If the resonator bell is substantially U-shaped in cross-section along the axis about which rotation is to be sensed, then it can conveniently be supported by a central mounting point on the axis.
One possible resonator bell shape is illustrated in
Figure 1A of the accompanying drawings. Pairs of piezoelectric drive transducers are conventionally attached to opposite sides of the resonator bell such that they cause the resonator bell to resonate as illustrated in cross section in Figure 1B and in plan view in Figure 2. The forces applied to the resonator bell cause the rim, or rims, to oscillate as shown in Figure 2, in the same manner in which a plastic beaker does when diametrically opposite edges of its upper lip are squeezed between thumb and forefinger. It can be seen from Figure 2 that if drive transducers are mounted on diameter A then this will become an antinode, and a corresponding antinode occurs on the diameter B perpendicular to diameter A.Drive sense transducers are mounted along diameter B, the outputs of which provide feedback to the input signal for drive transducers on diameter A, to maintain the energising of the resonator bell in phase with its resonant frequency.
From Figure 2 it can be seen that diameters C and D are nodal points. However if the resonator bell is rotated about axis X then Coriolis forces shift the antinodes around the axis X such that the amplitude of vibration along diameters C and D is proportional to the angular velocity about axis X. Rate sense transducers mounted on axis C and
D are used to provide a signal, the amplitude of which is dependent on the angular velocity of the resonator bell about axis X.
At present in gyroscopes of the above type the resonator resonator bell is supported at a fixed point such that the resonator bell is free to vibrate, and the transducers, which are normally piezoelectric material, are electrically connected to a rigid frame around the resonator bell by means of fine gold wires in order to avoid reducing the sensitivity of the resonator bell by the wires damping vibration. However the attachment of these fine wires to the piezoelectric transducers, typically numbering twelve or more, is a very slow and time consuming process.
It is the object of the present invention to provide a solid state transducer which is easier to manufacture than those presently available.
According to a first aspect of the present invention there is provided a solid state vibrational gyroscope comprising a resonator bell having a plurality of electromechanical transducers thereon, a printed circuit board, and means for mounting the resonator bell on the printed circuit board, wherein the transducers are retained in electrical contact with the conductive tracks on the printed circuit board by the mounting means.
By employing the present invention electrical connections are made between the resonator bell and the printed circuit board by the mounting, thereby eliminating the need to provide individual electrical connections to each transducer on the resonator bell.
Preferably the resonator bell has a substantially planar circular base portion remote from a rim, or rims, of the bell, and is secured by the mounting means at a central region of the base portion, via which central region electrical connections are made. As the central region of the base portion of the resonator bell is always a nodal point the resonator bell may be physically attached at this point without unduly affecting the sensitivity of the resonator bell.
Advantageously the transducers are piezoelectric transducers defined in a layer of piezoelectric material on the base portion of the resonator bell by electrodes deposited on the piezoelectric material, which electrodes extend to the central region. In such a gyroscope it is necessary to deposit the electrodes on the piezoelectric material, and therefore these electrodes can be extended to the central region of the base portion by the same process.
The mounting means can comprise insulating material having conductive tracks extending from conductive tracks on the printed circuit board to electrodes for making connection to the transducers on the resonator bell. The insulating material thereby provides a spacer for the resonator bell to space it apart from the printed circuit board and also provides the electrical contacts. The conductive tracks which make these electrical contacts can be formed by solder extending along the channels, or apertures, in the insulator material, which solder retains the resonator bell on the printed circuit board.Preferably these conductive tracks of solder extending along the channels, or apertures, are obtained by reflowing solder deposited on the resonator bell, printed circuit board, or both as this enables the resonator bell to be assembled by positioning the insulating material between the printed circuit board and the resonator bell and heating such that the solder reflows both making electrical contacts and structurally fixing the resonator bell in position.
In an alternative embodiment, the mounting means may comprise a raised portion on the printed circuit board over which the conductive tracks of the printed circuit board extend, or likewise the mounting means may comprise a raised portion on the surface of the resonator bell over which the conductive tracks to the electrodes for making connection to the transducers extend. In either embodiment the raised portion will space apart the resonator bell and printed circuit board and also bring the conductive tracks on the printed circuit board into electrical contact with the electrodes on the resonator bell. The mounting may conveniently comprise an adhesive which contracts on setting ensuring the resonator bell is in firm contact with the printed circuit board and that good electrical contact is established between the raised solder bumps.
In a further alternative embodiment the mounting can comprise a plurality of electrical contacts on the printed circuit board which are soldered to electrical contacts on the resonator bell. It is preferable that the electrical contacts on the printed circuit board are formed by vias extending through a layer of the printed circuit board to the conductive tracks. The thickness of the protruding portion of the vias thereby spacing the resonator bell from the printed circuit board.
According to a second aspect of the present invention there is provided a method of manufacturing a solid state vibrational gyroscope comprising the step of mounting a resonator bell of the gyroscope on a printed circuit board wherein the mounting process forms electrical connections between conductive tracks on the printed circuit board and electrodes on the resonator bell.
One embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings of which:
Figure 1A is a cross section of a resonator resonator bell suitable for use with the present invention;
Figure 1B is a schematic illustration of the cross sectional mode of vibration of the resonator bell of Figure 1A; Figure 2 is a plan view of the vibrational movement of the rim of the resonator bell of Figure lA; Figure 3 shows the electrode structure on a base portion of a resonator bell for use in the present invention;
Figure 4 illustrates a printed circuit board and mounting which, with the resonator bell of Figure 3, forms the present invention;;
Figures 5, 6, 7, 8, 9 and 10 illustrate alternative mounting arrangements for a vibrational gyroscope in accordance with the present invention; and
Figure 11 schematically illustrates the electrical circuit employed in operating a gyroscope in accordance with the present invention.
Referring to Figure 3 a resonator bell 30 having a
U-shaped longitudinal section, similar to that illustrated in Figure 1A, has a layer of piezoelectric material 32 and a layer of insulating material 33 on a lower surface. A plurality of electrodes 34 are deposited on the insulator 33, each having a conductive track 35 extending to solder bumps 36 in a central portion 37. Each electrode 35 defines a transducer in the piezoelectric material between the electrode and the resonator bell 30 which is of a conductive metallic material such as steel or aluminium. The arrangement of the electrodes, and therefore transducers is explained below with reference to Figure 10.
Referring now to Figure 4, there is illustrated a printed circuit board 40 with conductive tracks 41 connecting drive circuitry for the resonator bell in the form of integrated circuit chip 42 to mounting member 43, which is a ceramic disc with apertures therethrough. Each conductive track 41 terminates at a solder bump below a respective aperture in the ceramic disc 43. External connections to the gyroscope are made by a push on connector (not shown) connecting with conductive tracks 44.
Figure 5, in which like reference numerals have been used for like parts illustrated in Figures 3 and 4, illustrates the assembled gyroscope. The printed circuit board 40 and integrated circuit 42 have been connected to the resonator bell 30 of figure 3 by means of the ceramic disc 43. The gyroscope is assembled by placing the ceramic disc 43 on the printed circuit board, placing the resonator bell on the ceramic disc then heating the region of the ceramic disc 43 such that solder bumps on the resonator bell and printed circuit board melt. The solder then flows through the apertures 50 forming conductive tracks connecting respective pairs of conductive tracks and electrodes on the resonator bell and printed circuit board respectively, and also physically fixing the resonator bell to the printed circuit board.
There are many alternative ways of mounting the resonator bell on the printed circuit in accordance with the present invention, and a few of these are illustrated in
Figures 6 to 10. Referring to figure 6, there is illustrated an embodiment where a resonator bell 60 is mounted to the printed circuit board 61 by means of vias 62, plated through apertures in the printed circuit board.
Extended tracks 63 of piezoelectric material on the resonator bell are soldered to the vias 62, both maintaining the bell in position and making electrical contact to the conductive tracks 64.
In the figure 7 embodiment, ceramic disc 70 has tracks on the outside, which make contact with respective solder pads on both the bell and the printed circuit board. In the figure 8 embodiment the printed circuit board 80 has a raised annular portion 81, over which conductive tracks 82 extend such that when the resonator bell of figure 3 is deposited on them each track makes a connection with a respective electrode. The resonator bell can again be held in place by solder or alternatively can be attached by a central fixing, such as a screw as shown in Figure 9.
In Figure 10 a further alternative embodiment is illustrated in cross section, where a polyimide mounting 100 has a plurality of conductive elements 101, in the form of stiff metal wires. The mounting is bonded to both the resonator bell and the printed circuit board by adhesive which contracts on setting, ensuring good electrical contact between the electrodes, conductive tracks and the wires 101.
Figure 11 schematically illustrates the electrical circuitry that is connected to the electrodes of the resonator resonator bell of figures 3, 5 and 10. The terminals of this circuitry are labelled with the reference numbers of the electrodes on the resonator bell 111 which they respectively contact. Pairs of drive electrodes la, 1b and 2a, 2b are located perpendicular to each other on the base portion of the resonator bell 111 (which is shown inverted and without support structure for clarity). These electrodes define transducers in the piezoelectric material beneath them which are energised by amplifier 112 and inverse amplifier 113.
The expansion contraction of the piezoelectric material beneath the electrodes la, lb, 2a and 2b, causes the resonator bell 101 to deform as illustrated in figure 1B and figure 2. This is due to lateral expansion contraction of the piezoelectric material causing the base to which it is attached to bend in the same way that a bi-metallic strip bends when heated.
Electrodes 7, 8, 9 and 10 define in the piezoelectric material drive sense transducers which detect vibration within the resonator bell 111. Signals from these transducers are fed to differential amplifier 114, the output of which is fed to phase locked loop 115 which is amplitude stabilised, such that the amplifiers 112 and 113 drive the resonator bell at its resonant frequency.
Differential amplifier 116 receives an input from electrodes 3 and 4, which define rate sense transducers in the piezoelectric material. These electrodes lie on nodes 117 and 118, and, in the absence of rotation of the gyroscope, provides a zero output. This is because each rate sense transducer defined by the electrode 3 and 4 has an equal area to either side of the nodal line, and therefore any voltage induced in one half will be cancelled by the opposite voltage being induced in the other half. On rotation of the resonator bell, the nodal lines 117, 118 rotate such that the voltage generated in one half of each rate sense transducer is greater than that generated in the other half, due to the area of each transducer to one side of the nodal line being greater than that to the other. The signals from electrodes 3 and 4 are in opposite sense so that differential amplifier 116 provides an output at the resonant frequency of the resonator bell when the resonator bell is rotated. The amplitude of the output is dependent on the rate of rotation.
Part of the output from differential amplifier 106 is phase shifted by phase shifter 119 which introduces a 900 phase shift. This signal drives amplifiers 120 and inverse amplifier 121, which are respectively connected to electrodes 5 and 6 of the bell. This causes transducers defined by the piezoelectric material below electrodes 5 and 6 to damp the vibration at the natural nodal lines.
The output of differential amplifier 116 also passes through band pass filter 122, which is tuned to the resonant frequency of the resonator bell to prevent spurious signals, arising from other vibrations induced into the resonator bell, from influencing the output signal of the gyroscope.
This signal is then fed to phase sensitive detector 123 which also receives a signal from the drive loop 114, 115, 112, 113 and 111. The phase sensitive detector 123 receives two in phase sine wave signals plus any other signals due to spurious noise. The two sine wave signals combine to give a full wave rectified output which passes through low pass filter 124 to output 125. The amplitude of this output is dependent upon the rate of rotation of gyroscope. Any spurious signals received by the phase sensitive detector 123 have a higher frequency component and are rejected by low pass filter 124.
Claims (16)
1. A solid state vibrational gyroscope comprising a resonator bell having a plurality of electromechanical transducers thereon, a printed circuit board, and means for mounting the resonator bell on the printed circuit board, wherein the transducers are retained in electrical contact with the conductive tracks on the printed circuit board by the mounting means.
2. A gyroscope as claimed in claim 1 wherein the resonator bell has a substantially planar circular base portion remote from a rim, or rims, of the bell and is secured by the mounting means at a central region of the base portion via which central region the electrical connections are made.
3. A gyroscope as claimed in claim 2 wherein the transducers are piezoelectric transducers defined in a layer of piezoelectric material on the base portion of the resonator bell by electrodes deposited on the piezoelectric material, which electrodes extend to the central region.
4. A gyroscope as claimed in any preceding claim wherein the mounting means comprises insulating material having conductive tracks extending from conductive tracks on the printed circuit board to electrodes for making connection to the transducers on the resonator bell.
5. A gyroscope as claimed in claim 4 wherein the conductive tracks are formed by solder extending along channels or apertures in the insulator material, which solder retains the resonator bell on the printed circuit board.
6. A gyroscope as claimed in claim 5 wherein the conductive tracks of solder extending along the channels or apertures are obtained by reflowing solder deposited on the resonator bell, printed circuit board, or both.
7. A gyroscope as claimed in any one of claims 1 to 4 wherein the mounting means comprises a raised portion on the printed circuit board over which the conductive tracks of the printed circuit board extend.
8. A gyroscope as claimed in any one of claims 1 to 4 wherein the mounting means comprises a raised portion on the surface of the resonator bell over which electrodes for making connection to the transducers extend.
9. A gyroscope as claimed in claim 7 and claim 8.
10. A gyroscope as claimed in any one of claims 1 to 4, 7, 8 or 9 wherein the mounting comprises an adhesive which contracts on setting.
11. A gyroscope as claimed in any one of claims 1 to 3 wherein the mounting comprises a plurality of electrical contacts on the printed circuit board which are soldered to electrical contacts on the resonator bell.
12. A gyroscope as claimed in claim 11 wherein the electrical contacts on the printed circuit board are formed by via's extending through a layer of the printed circuit board to the conductive tracks.
13. A gyroscope substantially as hereinbefore described with reference to, or as illustrated in any one of Figures 3 to 10 of the accompanying drawings.
14. A method of manufacturing a solid state vibrational gyroscope comprising the step of mounting a resonator bell of the gyroscope on a printed circuit board wherein the mounting process forms electrical connections between conductive tracks on the printed circuit board and electrodes on the resonator bell.
15. A method as claimed in claim 14 wherein the mounting process includes placing a spacer between the resonator bell and the printed circuit board, which spacer has apertures or channels therein, and heating the region in which the spacer is located such that solder deposited on one, or both, of the resonator bell and printed circuit board flows along the apertures or channels forming electrical contact between the conductive tracks on the printed circuit board and the electrodes on the resonator bell.
16. A method of manufacturing a solid state gyroscope substantially as hereinbefore described with reference to, or as illustrated in, figures 3 to 9 of the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9222980A GB2272054A (en) | 1992-11-03 | 1992-11-03 | Solid state vibrational gyroscope |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9222980A GB2272054A (en) | 1992-11-03 | 1992-11-03 | Solid state vibrational gyroscope |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2272054A true GB2272054A (en) | 1994-05-04 |
Family
ID=10724433
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9222980A Withdrawn GB2272054A (en) | 1992-11-03 | 1992-11-03 | Solid state vibrational gyroscope |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2272054A (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2378517A (en) * | 2000-05-22 | 2003-02-12 | Toyota Motor Co Ltd | Sensing device having a vibrator displaceably supported with respect to a substrate and directed in a downward direction when the device is operated |
| FR2969751A1 (en) * | 2010-12-22 | 2012-06-29 | Sagem Defense Securite | VIBRANT GYROSCOPE, AND PROCESSING METHOD |
| US8991249B2 (en) | 2011-05-23 | 2015-03-31 | Sagem Defense Securite | Vibrating gyroscope and treatment process |
| JP2016031237A (en) * | 2014-07-25 | 2016-03-07 | ローム株式会社 | MEMS piezoelectric sensor |
| US20160334438A1 (en) * | 2015-05-15 | 2016-11-17 | Invensense, Inc. | Offset rejection electrodes |
| US10295558B2 (en) | 2015-05-15 | 2019-05-21 | Invensense, Inc. | Offset rejection electrodes |
| US11231441B2 (en) | 2015-05-15 | 2022-01-25 | Invensense, Inc. | MEMS structure for offset minimization of out-of-plane sensing accelerometers |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2061502A (en) * | 1979-10-19 | 1981-05-13 | Marconi Co Ltd | A Sensor for Detecting Rotational Movement |
| GB2164749A (en) * | 1984-09-07 | 1986-03-26 | Marconi Co Ltd | Vibrational gyroscope |
| GB2208318A (en) * | 1987-07-24 | 1989-03-22 | Yazaki Corp | A glass vacuum housing for a vibratory turn-sensitive device |
-
1992
- 1992-11-03 GB GB9222980A patent/GB2272054A/en not_active Withdrawn
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2061502A (en) * | 1979-10-19 | 1981-05-13 | Marconi Co Ltd | A Sensor for Detecting Rotational Movement |
| GB2164749A (en) * | 1984-09-07 | 1986-03-26 | Marconi Co Ltd | Vibrational gyroscope |
| GB2208318A (en) * | 1987-07-24 | 1989-03-22 | Yazaki Corp | A glass vacuum housing for a vibratory turn-sensitive device |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2378517A (en) * | 2000-05-22 | 2003-02-12 | Toyota Motor Co Ltd | Sensing device having a vibrator displaceably supported with respect to a substrate and directed in a downward direction when the device is operated |
| GB2378517B (en) * | 2000-05-22 | 2003-08-06 | Toyota Motor Co Ltd | Sensing device and sensor apparatus |
| FR2969751A1 (en) * | 2010-12-22 | 2012-06-29 | Sagem Defense Securite | VIBRANT GYROSCOPE, AND PROCESSING METHOD |
| US8991249B2 (en) | 2011-05-23 | 2015-03-31 | Sagem Defense Securite | Vibrating gyroscope and treatment process |
| JP2016031237A (en) * | 2014-07-25 | 2016-03-07 | ローム株式会社 | MEMS piezoelectric sensor |
| US20160334438A1 (en) * | 2015-05-15 | 2016-11-17 | Invensense, Inc. | Offset rejection electrodes |
| US9952252B2 (en) * | 2015-05-15 | 2018-04-24 | Invensense, Inc. | Offset rejection electrodes |
| US10295558B2 (en) | 2015-05-15 | 2019-05-21 | Invensense, Inc. | Offset rejection electrodes |
| US10466268B2 (en) | 2015-05-15 | 2019-11-05 | Invensense, Inc. | Offset rejection electrodes |
| US11231441B2 (en) | 2015-05-15 | 2022-01-25 | Invensense, Inc. | MEMS structure for offset minimization of out-of-plane sensing accelerometers |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0859219B1 (en) | A vibrating structure gyroscope | |
| JP3007216B2 (en) | Inertial rate detector for tuning fork with one end closed | |
| US7849572B2 (en) | Method of manufacturing a piezoelectric device | |
| US5698784A (en) | Vibratory rate gyroscope and methods of assembly and operation | |
| US5396144A (en) | Rotation rate sensor with center mounted tuning fork | |
| EP0881465B1 (en) | Vibrating gyroscope | |
| JPH053536B2 (en) | ||
| JPH0777538A (en) | Rotational speed sensor with built-in type test circuit | |
| US5757107A (en) | Tuning-fork vibratory gyro and sensor system using the same | |
| US8225663B2 (en) | Tuning fork-type vibrator, tuning fork-type vibrator manufacturing method, and angular velocity sensor | |
| JP2006105614A (en) | Vibrating gyroscope and manufacturing method of vibrating gyroscope | |
| KR20070040727A (en) | Angular velocity sensor | |
| GB2272054A (en) | Solid state vibrational gyroscope | |
| EP0800058A2 (en) | Vibrating gyroscope | |
| US5635641A (en) | Vibratory gyroscope with reduced stress and stable characteristics | |
| GB2272053A (en) | A solid state vibrational gyroscope | |
| JPH11287658A (en) | Vibrating gyro | |
| KR20080020529A (en) | Vibration sensor | |
| JP3286902B2 (en) | Vibrator support structure | |
| EP0751375B1 (en) | Vibrating gyroscope | |
| JP2005321221A (en) | Piezoelectric vibrator | |
| JP5277593B2 (en) | Angular velocity sensor | |
| JP2004138390A (en) | Oscillator support structure | |
| US20080105051A1 (en) | Vibration sensor and method for manufacturing the same | |
| JP2005308683A (en) | Piezoelectric vibrator |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |