US1899163A - Piezo-electric crystal - Google Patents
Piezo-electric crystal Download PDFInfo
- Publication number
- US1899163A US1899163A US492668A US49266830A US1899163A US 1899163 A US1899163 A US 1899163A US 492668 A US492668 A US 492668A US 49266830 A US49266830 A US 49266830A US 1899163 A US1899163 A US 1899163A
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- Prior art keywords
- frequency
- resonator
- piezo
- crystal
- temperature
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- 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.)
- Expired - Lifetime
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- 239000013078 crystal Substances 0.000 title description 17
- 239000010453 quartz Substances 0.000 description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 5
- 230000000694 effects Effects 0.000 description 4
- 230000005540 biological transmission Effects 0.000 description 2
- 230000008878 coupling Effects 0.000 description 2
- 238000010168 coupling process Methods 0.000 description 2
- 238000005859 coupling reaction Methods 0.000 description 2
- 238000005259 measurement Methods 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 101100400378 Mus musculus Marveld2 gene Proteins 0.000 description 1
- 241000009328 Perro Species 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
- H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
- H03H9/19—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator consisting of quartz
Definitions
- This invention relates to piezo-electr1c crystals and particularly to crystals having a small temperature coeflicient of frequency, and methods of cutting such crystals.
- An object of this invention is to provide a piezo-electric resonator whose resonant frequency of vibration does not change with variations in temperature.
- a feature of this invention is a disc shaped piezoelectric-resonator having a zero temperature coefficient of frequency.
- the drawing shows perspective views of a series of piezo-electric resonators of the invention, formed from a single crystal, the resonator of Fig. 2 having been cut from that of Fig. 1, and the resonator of Fig. 3 having been cut from that of Fig. 2.
- the stiffness, and the temperature coefficient of stiffness, of quartz crystals are dif ferent along difierent axes.
- the effective stiffness along any given axis is the sum of at least two effects, one being the usual mechanical stiffness, such as exists in ordinary 150- Serial N0. 492,668.
- the effective stiffness which determines the resonant frequency of a resonator in a given mode is a complex quantity dependent on the relative dimensions along different resonator axes, the orientation with respect to the original crystal axes, the size, number, spacing, and arrangement of electrodes about the resonator, the voltage impressed upon the resonator in various directions in relation to the dimensions and orientation of the resonator, and the impedance of the electrical circuit to which the resonator is coupled.
- the inherent temperature coefficient of frequency is different along an electrical axis of a crystal from that in a perpendicular direction along'a crystallographic axis.
- a disc shaped plate is out from a quartz crystal in the plane of an electrical axis and the optical axis and having a sufficiently large cross-sectional area in proportion to its thickness, as in Fig. 1 without the center removed, it will be found to have a positive temperature coefficient of frequency. If an outer rim is removed and another measurement is taken of the resulting disc, having greater thickness in proportion to its crosssectional area, as Fig. 2 without the center removed, it will be found to have a smaller positive temperature coefficient of frequency. If another rim is removed from the smaller plate, the temperature coeflicient of frequency of the resulting disc, as in Fig. 3 will again be found to have decreased. It will continue to decrease passing through zero to negative values. These measurements are, of course, all made at the same temperature so the crystal will vibrate at the desired frequency at a desired temperature.
- a disc is first cut from a crystal parallel to an electrical axis and the optical axis, ground to the thickness corresponding to a frequency slightly lower than the frequency desired, and its temperature coefficient adjusted by grinding the periphery until the point has been reached where it has a slightly negative temperature coefficient. A final adjustment of frequency and temperature coetficient is then made by grinding to the proper thickness.
- resonators which have a zero temperature coeflicient of frequency are that the necessity for temperature controlling means is avoided, and furthermore as the resonator heats up due to load applied to it, the frequency does not change due to either the initial heating or to variations in load.
- a quartz crystal piezo-electric resonator disc the plane of which is parallel to the
Landscapes
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
- Oscillators With Electromechanical Resonators (AREA)
Description
Elli 158991163 F'eb. 28, 1933.
W. A. MARRISON PIEZO ELECTRIC CRYSTAL Original Filed Dec. 19, 1928 /NVEN7'0/? WAMA PRISON gt/y 7T ATTORNEY Patented Feb. 28, 1933 UNITED STATES PATENT OFFICE WARREN A MARRISON, 0F MAPLEWOOD, NEW JERSEY, ASSIGNOR TO BELL TELEPHONE LABORATORIES, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK PIEZO-ELECTRIC CRYSTAL Original application filed December 19, 1928, Serial No. 327,017. Divided and this application filed November 1, 1930.
This application is a division of my copending application Serial No. 327,017, filed December 19, 1928.
This invention relates to piezo-electr1c crystals and particularly to crystals having a small temperature coeflicient of frequency, and methods of cutting such crystals.
The advantages of utilizing the piezo-elec tric effect of substances possessing such properties have been known for some time. The uses for a constant frequency control and especially the need of such control within more rigid limits, are constantly increasing. Such uses include the control of broadcasting stations on their assigned wave lengths, Whether locally or by transmission of a wave from a central control point, and control of the frequency of local oscillations in a heterodyne receiver. Frequency control means are also useful in connection with sending and receiving sets of picture transmission and television in order to avoid the necessity of a synchronization channel and similarly in systems of carrier Wave telephony and telegraphy, and are also important elements of laboratory reference standards.
An object of this invention is to provide a piezo-electric resonator whose resonant frequency of vibration does not change with variations in temperature.
A feature of this invention is a disc shaped piezoelectric-resonator having a zero temperature coefficient of frequency.
The drawing shows perspective views of a series of piezo-electric resonators of the invention, formed from a single crystal, the resonator of Fig. 2 having been cut from that of Fig. 1, and the resonator of Fig. 3 having been cut from that of Fig. 2.
The stiffness, and the temperature coefficient of stiffness, of quartz crystals, are dif ferent along difierent axes. The effective stiffness along any given axis is the sum of at least two effects, one being the usual mechanical stiffness, such as exists in ordinary 150- Serial N0. 492,668.
tropic substances, and another being due to the reaction of the electric field set up within and around a piece of mechanically strained piezo-electrically active material.
When an elastic body is deformed in a given direction by a force applied in that direction, there is a corresponding, but smaller deformation in the perpendicular direction, as well as a change in volume. When a quartz resonator isset in resonant vibration, there is a large periodic change of length in one direction, called the direction of vibration, and a Vibration of the same frequency in a transverse direction. The transverse vibration is due partly to the mechanical tendency of the material to maintain constant volume, partly to the mechanical coupling between the two modes of vibration, and partly to the electrical coupling between the electrodes and the resonator perpendicular to the principal direction of vibration. Thus the effective stiffness which determines the resonant frequency of a resonator in a given mode is a complex quantity dependent on the relative dimensions along different resonator axes, the orientation with respect to the original crystal axes, the size, number, spacing, and arrangement of electrodes about the resonator, the voltage impressed upon the resonator in various directions in relation to the dimensions and orientation of the resonator, and the impedance of the electrical circuit to which the resonator is coupled.
Because of the various factors above mentioned which determine the stiffness characteristics for given modes of vibration, there results a similar complexity as to the temperature cocflicient of stilfness for the corresponding modes of vibration, hence it tends to result that the temperature coefficient of stiffness, and therefore the frequency, of a resonator in a given mode may be varied over a considerable range by suitably proportioning the resonator.
The inherent temperature coefficient of frequency is different along an electrical axis of a crystal from that in a perpendicular direction along'a crystallographic axis. (A discussion of the axes of a quartz crystal may be found in a paper on the Uses and Possibilities of Piezo-Electric Crystals, by Auust Hund, in the Journal of the Institute of lfadio Engineers, for August, 1926, commencing on page 447.)
If a disc shaped plate is out from a quartz crystal in the plane of an electrical axis and the optical axis and having a sufficiently large cross-sectional area in proportion to its thickness, as in Fig. 1 without the center removed, it will be found to have a positive temperature coefficient of frequency. If an outer rim is removed and another measurement is taken of the resulting disc, having greater thickness in proportion to its crosssectional area, as Fig. 2 without the center removed, it will be found to have a smaller positive temperature coefficient of frequency. If another rim is removed from the smaller plate, the temperature coeflicient of frequency of the resulting disc, as in Fig. 3 will again be found to have decreased. It will continue to decrease passing through zero to negative values. These measurements are, of course, all made at the same temperature so the crystal will vibrate at the desired frequency at a desired temperature.
To cut a disc shaped resonator with a zero temperature coefficient of frequency, a disc is first cut from a crystal parallel to an electrical axis and the optical axis, ground to the thickness corresponding to a frequency slightly lower than the frequency desired, and its temperature coefficient adjusted by grinding the periphery until the point has been reached where it has a slightly negative temperature coefficient. A final adjustment of frequency and temperature coetficient is then made by grinding to the proper thickness.
It is necessary to make the adjustment in three steps instead of two because the first adjustment of frequency has an effect on the temperature coefficient, and the adjustment of the temperature coefiicient has a very slight effect on the frequency. If the exact dimensions are known for a desired frequency with a zero temperature coefficient at a given orientation of the resonator with respect to its crystal axes, it may be out directly to these dimensions in two steps.
Advantages of resonators which have a zero temperature coeflicient of frequency are that the necessity for temperature controlling means is avoided, and furthermore as the resonator heats up due to load applied to it, the frequency does not change due to either the initial heating or to variations in load.
What is claimed is:
1. A quartz crystal piezo-electric resonator disc, the plane of which is parallel to the
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US492668A US1899163A (en) | 1928-12-19 | 1930-11-01 | Piezo-electric crystal |
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US327017A US1907425A (en) | 1928-12-19 | 1928-12-19 | Piezo electric resonator |
US492668A US1899163A (en) | 1928-12-19 | 1930-11-01 | Piezo-electric crystal |
US497783A US1907427A (en) | 1928-12-19 | 1930-11-24 | Piezo-electric crystal |
Publications (1)
Publication Number | Publication Date |
---|---|
US1899163A true US1899163A (en) | 1933-02-28 |
Family
ID=27406495
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US492668A Expired - Lifetime US1899163A (en) | 1928-12-19 | 1930-11-01 | Piezo-electric crystal |
Country Status (1)
Country | Link |
---|---|
US (1) | US1899163A (en) |
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1930
- 1930-11-01 US US492668A patent/US1899163A/en not_active Expired - Lifetime
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