GB2044526A - Method of adjusting a frequency of vibration of a tuning fork type piezo-electric vibrator - Google Patents
Method of adjusting a frequency of vibration of a tuning fork type piezo-electric vibrator Download PDFInfo
- Publication number
- GB2044526A GB2044526A GB7943144A GB7943144A GB2044526A GB 2044526 A GB2044526 A GB 2044526A GB 7943144 A GB7943144 A GB 7943144A GB 7943144 A GB7943144 A GB 7943144A GB 2044526 A GB2044526 A GB 2044526A
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- United Kingdom
- Prior art keywords
- vibration
- vibrator
- mode
- tuning fork
- frequency
- 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.)
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Links
- 238000000034 method Methods 0.000 title claims abstract description 32
- 239000000463 material Substances 0.000 claims abstract description 10
- 239000013078 crystal Substances 0.000 claims description 46
- 239000010453 quartz Substances 0.000 claims description 44
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 44
- 238000000151 deposition Methods 0.000 claims description 12
- 230000008021 deposition Effects 0.000 claims description 11
- 230000003247 decreasing effect Effects 0.000 claims 2
- 238000005259 measurement Methods 0.000 abstract description 2
- 238000005520 cutting process Methods 0.000 description 13
- 230000010355 oscillation Effects 0.000 description 8
- 210000000707 wrist Anatomy 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 5
- 230000008878 coupling Effects 0.000 description 4
- 238000010168 coupling process Methods 0.000 description 4
- 238000005859 coupling reaction Methods 0.000 description 4
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 3
- 230000008020 evaporation Effects 0.000 description 3
- 238000001704 evaporation Methods 0.000 description 3
- 229910052709 silver Inorganic materials 0.000 description 3
- 239000004332 silver Substances 0.000 description 3
- 239000000306 component Substances 0.000 description 2
- 230000005684 electric field Effects 0.000 description 2
- 238000004544 sputter deposition Methods 0.000 description 2
- 238000013459 approach Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005530 etching Methods 0.000 description 1
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 1
- 229910052737 gold Inorganic materials 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 230000003340 mental effect Effects 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
- H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
- H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
- H03H3/04—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks for obtaining desired frequency or temperature coefficient
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic elements; Electromechanical resonators
- H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
- H03H9/21—Crystal tuning forks
- H03H9/215—Crystal tuning forks consisting of quartz
Landscapes
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
Abstract
A method of adjusting a frequency of vibration of a tuning fork type piezo-electric vibrator (10) which, in operation, vibrates in coupled modes, the said method comprising adjusting the weight of at least one portion (13) of the vibrator, the position of the or each said portion (13) being selected in dependence upon the deviations of the frequencies of said modes from their desired values. Apparatus is described in which material is deposited on the vibrator through an apertured plate which is movable by a drive arrangement controlled by measurements of the frequencies. <IMAGE>
Description
SPECIFICATION
Method of adjusting a frequency of vibration of a tuning fork type piezo-electric vibrator
This invention concerns a method of adjusting a frequency of vibration of a tuning fork type piezo-electric vibrator and, although the invention is not so restricted, it is more particularly concerned with the adjustment of a frequency of vibration of a tuning fork type quartz-crystal vibrator.
According to the present invention, there is provided a method of adjusting a frequency of vibration of a tuning fork type piezo-electric vibrator which, in operation, vibrates in coupled modes, the said method comprising adjusting the weight of at least one portion of the vibrator, the position of the or each said portion being selected in dependence upon the frequencies of said modes.
The adjustment of the weight of the at least one portion may be effected either by adding weight to said portion, or by removing it therefrom e.g. by means of a laser.
The said position is preferably selected in dependence upon the extents to which the frequencies of said modes differ from predetermined values thereof.
Thus the said position may depend upon the ratio of the differences between the actual frequencies of the two modes and predetermined frequencies thereof.
The deposition of the material is preferably continued until the frequency of one of said modes has a predetermined value.
In one embodiment, the predetermined value of the said mode is not the final desired value thereof, and, after the predetermined value has been achieved, the above-mentioned method is repeated so that the frequency of the said mode reaches the final desired value.
The repetition of the method may involve the deposition of material at at least one position which differs from that at which the material was originally deposited.
A slit plate may be mounted for movement parallel to the vibrator, the slit plate being interposed between a deposition source and the vibrator, and there being means for moving the slit plate in dependence upon the frequencies of said modes.
A shutter may be interposed between the slit plate and the vibrator.
The slit plate, deposition source and vibrator may be mounted in a vacuum chamber.
Preferably the modes are flexural and tor- sional modes. For example, the first overtone of the flexural mode may be coupled to the fundamental vibration of the torsional mode.
Preferably a main mode of vibration is coupled to a secondary mode thereof, the frequency of the main mode being adjusted by the adjustment of the weight.
The invention is illustrated, merely by way of example, in the accompanying drawings, in which:
Figure 1 is a perspective view of a conventional tuning fork type quartz crystal vibrator and shows the directions of vibration in the tuning fork arms thereof,
Figure 2 is a graph which shows the resonant frequency-temperature characteristics of the tuning fork type quartz crystal vibrator of
Fig. 1,
Figure 3 is a diagram which shows how a mode coupled tuning fork type quartz crystal vibrator may be cut from quartz crystal,
Figure 4 is a graph which shows the first temperature coefficient with respect to the thickness of the tuning fork type quartz crystal vibrator and the difference between the resonant frequency and the first overtone vibration of the flexural mode of vibration and the resonant frequency of the fundamental vibration of the torsional mode of vibration,
Figure 5 is a graph which shows the second temperature coefficient with respect to the cutting angle of the tuning fork type quartz crystal vibrator,
Figure 6 is a graph which shows the resonant frequency-temperature characteristics of the conventional tuning fork type quartz crystal vibrator and the mode coupled tuning fork type quartz crystal vibrator,
Figure 7 is a graph which shows a curve of the best frequency-temperature characteristic in the region from 0,C to 40"C, Figure 8 is a perspective view of a mode coupled tuning fork type quartz crystal vibrator in accordance with this invention,
Figure 9 is a mode chart illustrating the situation In which the cutting angle, the width and the length of the vibrator are equal to the most suitable values and the thickness thereof is variable,
Figure 10 is a graph which shows a position of a weight and the ratio of change of resonant frequencies of two modes of vibration, and
Figure 11 shows a device for the frequency adjustment of one embodiment of a mode coupled tuning fork type quartz crystal vibrator in accordance with the invention.
Fig. 1 is a perspective view of a conventional tuning fork type quartz crystal vibrator 1 in which the directions of vibration in the tuning fork arms are indicated. The tuning fork type quartz crystal vibrator 1 has two tuning fork arms 1 a extending from a base 1 b. 2 are electrodes, 3 is a plug to support the vibrator. Arrows 4 indicate the directions of vibration in the two tuning fork arms 1 a at a certain time. Arrows 5 indicate the directions of vibration in the two tuning fork arms 1 a after one-half of the period of oscillation has passed. As indicated by the arrows 4 and 5, the two tuning fork arms 1 a experience the flexural mode of vibration, the fixed ends of which (i.e. their ends adjacent the base 1 b) are roots of the tuning fork arms.The resonant frequencies of most vibrators are less than 100 KHz. A vibrator for an electronic wrist watch is of low frequency and small size since such a vibrator uses less power.
Fig. 2 shows the resonant frequent-temperature characteristic of the tuning fork type quartz-crystal vibrator in Fig. 1. The abscissa represents the temperature and the ordinate represent the variations of the resonant frequency. (If the resonant frequencies af T"C and 20"C are respectively fT and f20, then the variation is given in the form of (fT - f20)/f20, hereinafter referred to as Af/f). The resonant frequency-temperature characteristic is a parabolic curve having a peak thereof at the normal temperature. The second temperature coefficient is about -35 X 10-9/"C2.
When such a conventional tuning fork type quartz crystal vibrator is used for an electronic wrist watch, the considerable change of resonant frequency with temperature which is shown in Fig. 2 leads to time error. Hitherto, a thermosensitive element such as a capacitor using a dielectric substance, or a thermistor has been included in an oscillator circuit in order to compensate the resonant frequencytemperature characteristic. However, since the characteristic of such a thermosensitive element does not agree with the resonant frequency-temperature characteristic af the quartz crystal vibrator, the resonant frequencytemperature characteristic is not completely compensated.In the mass production of electronic wrist watches, some wrist watches are produced having a temperature characteristic af the oscillation frequency which is inferior to an uncompensated temperature characteristic due to the variation or to the difference in characteristics of the thermo-sensitive element and the quartz crystal vibrator.
A thickness-shear quartz crystal vibrator which itself has a good resonant frequencytemperature characteristic has been used to avoid the above faults. The resonant frequency-temperature characteristic of the thickness-shear quartz crystal vibrator is a cubic curve at the normal temperature. This vibrator has a good temperature characteristic in which the change of the resonant frequency in the region 0 to 40"C is 1/10 of the corresponding change of a tuning fork type quartz crystal vibrator having the flexural mode of vibration. However, since the thickness-shear quartz crystal vibrator has an extremely high resonant frequency of several MHz, when the vibrator is used for an electronic wrist watch, the current required for oscillation and frequency division is increased and the battery life is made extremely short.
A quartz crystal vibrator used for an electronic wrist watch requires a low resonant frequency, in order to achieve low power
consumption, and a good resonant frequencytemperature characteristic, in order to achieve
time accuracy. These requirements can be
satisfied by employing a tuning fork type
quartz crystal vibrator in which there is cou
pling between two different modes of vibra
tion. (Hereinafter such a vibrator is referred to
as a mode coupled tuning fork type quartz
crystal vibrator).
Such a mode coupled tuning fork quartz
crystal vibrator may be cut from quartz crystal
as shown in Fig. 3. The X axis, Y axis and Z
axis are respectively an electric axis, a me
chanical axis and an optical axis of quartz
crystal. The tuning fork type vibrator is cut
from a quartz crystal plate which is rotated
about about the X axis by an angle H (theta)
so that the longitudinal direction of the tuning
fork arm is directed toward the Y axis. When
electrodes are arranged in the same manner
as Fig. 1 on the vibrator thus made and the
vibrator is excited with alternating current,
components of the electric field in the X axis
direction are produced within the tuning fork
arms.In each tuning fork arm, the compo
nents of the electric field cause the flexural
mode of vibration and the torsional mode of
vibration, the axis of which is the centre of
the longitudinal direction of the tuning fork
arm. At this time, the fundamental vibration
and the overtone vibration are excited in both
the flexural mode of vibration and the tor
sional mode of vibration.
Coupling occurs when the resonant fre
quency of the torsional mode of vibration
approaches the resonant frequency of the first
overtone which is about six times the resonant
frequency of the fundamental vibration of the
flexural mode of vibration. In practice such a
coupling phenomenon is achieved by control
ling the thickness of the tuning fork arms.
That is to say, use is made of the fact that,
although the resonant frequency of the flex
ural mode of vibration scarcely depends on
the thickness, the resonant frequency of the
torsional mode of vibration is increased as the
tuning fork arms are thickened.
Fig. 4 shows the difference fF-fr between
the resonant frequency fF of the first overtone
vibration of the flexural mode of vibration and
the resonant frequency fT af the fundamental
vibration of the torsional mode of vibration,
and the first temperature coefficient a of the
first overtone vibration of the flexural mode of
vibration, when the thickness t is changed.
The abscissa represents the thickness, the
value of the thickness increasing in the direc
tion of the arrow. The left ordinate represents
the first temperature coefficient a, the right
ordinate represents the resonant frequency
difference fF-fT, and the direction of the arrow
from the point 0 is positive. As will be seen
from Fig. 4 there is a thickness at which the
first temperature coefficient of the first overtone vibration of the flexural mode of vibration is zero.
Fig. 5 shows the second temperature coefficient ss of the first overtone vibration of the flexural mode of vibration with respect to the cutting angle O (theta). The abscissa represents the cutting angle 8, and the ordinate represents the second temperature coefficient ss. The curve satisfies the condition that the first temperature coefficient a is zero at any point on the curve.
As will be seen from Figs. 4 and 5, there is a thickness t and a cutting angle 8 at which the first temperature coefficient a and the second temperature coefficient ss of the first overtone vibration of the flexural mode of vibration are zero. At this time, the resonant frequency-temperature characteristic depends on the third temperature coefficient y.
Fig. 6 shows the resonant frequent-temperature characteristics of the conventional tuning fork type quartz crystal vibrator and of the mode coupled tuning fork type quartz crystal vibrator. The abscissa represents the temperature and the ordinate represents the variation of the resonant frequency. 6 shows the resonant frequency-temperature characteristic of the conventional tuning fork type quartz crystal vibrator. 7 shows the resonant frequencytemperature characteristic of the mode coupled tuning fork type quartz crystal vibrator.
The reason why the temperature characteristic 7 is a cubic curve with respect to the temperature is that the first temperature coefficient a and the second temperature coefficient ss is zero. The change of resonant frequency of the mode coupled vibrator in the region 0 C to 40"C is 1/10 of the corresponding change of the conventional tuning fork vibrator. When ss is zero and a is about -300y, the inflection points 8 and 9 on the frequency-temperature characteristic curve respectively have the values of resonant frequency at 40"C and 0 C as shown in Fig. 7. At this time, the change of resonant frequency in the region 0 C to 40"C is further lessened.In addition, when ss is about 1 5y and a is about - 300y, the low temperature characteristic is greatly improved.
Thus, a and P with respect to y are optionally determined according to requirements.
If one uses a tuning fork type quartz crystal vibrator in which two different modes of vibration are coupled for an electronic wrist watch, the current consumption is reduced since the oscillation frequency thereof is 200 KHz or so, and the time accuracy is greatly improved since the change of resonant frequency is 1 /1 0to of that of the conventional tuning fork type quartz crystal vibrator.
The resonant frequency-temperature characteristic of the mode coupled tuning fork type quartz crystal vibrator depends on the cutting angle 8 and its external dimensions (the lengths of the tuning fork arms, and the overall thickness, width and length). In particular, the external dimensions have a considerable effect on the resonant frequency-temperature characteristic. The variations of the cutting angle O and the external dimensions which occur in mass production of such a mode coupled tuning fork type quartz crystal vibrator cause the variation of the resonant frequency-temperature characteristic.Although the variation of the cutting angle during mass production is almost controlled by selecting the quartz crystal plates, the control of the external dimensions by the present processing technique is difficult since the influence of the external dimensions on the resonant frequency-temperature characteristic is consderable. In particular, since the resonant frequency-temperature characteristic largely depends on the thickness and a control of thickness of under 0.1 lb is required, it is impossible to control the thickness by grinding. Besides, although it is possible to control the thickness by etching after the thickness of each vibrator has been measured, the yield of accepted articles is then low.Moreover, in the case where the vibrator is manufactured by a lithographic process, many manufacturing processes are required since a unified process is impossible.
An object of this invention is to decrease the variation of the resonant frequency-temperature characteristic of the mode coupled tuning fork type quartz crystal vibrator and to adjust the frequency at the same time at a low price.
Fig. 8 is a perspective view of an embodiment in accordance with this invention. 10 is a mode coupled tuning fork type quartz crystal vibrator having two tuning fork arms 1 0a.
The vibrator 10 has a main mode of vibration, which is constituted by the first overtone vibration of the flexural mode of vibration, this mode being coupled to a secondary mode of vibration which is constituted by fundamental vibration of the torsional mode of vibration.
11 are electrodes, 1 2 is a plug, 1 3 are silver weights each of which is deposited e.g. by evaporation, between the end of the respective tuning fork arm 1 0a and the nodal point of the vibration. In the conventional tuning fork type quartz crystal vibrator shown in Fig.
1, gold or silver have been deposited on the end of the tuning fork arm as a weight, in order merely to adjust the oscillation frequency. However, the weights 1 3 in Fig. 8 are for the adjustment not only of the oscillation frequency but also of the resonant frequency-temperature characteristic. Such a mode coupled vibrator has a resonant frequency-temperature characteristic constituted by a cubic curve as shown by 7 in Fig. 6.
Fig. 9 is a mode chart of the coupling with respect to the thickness of the mode coupled tuning fork type quartz crystal vibrator when the cutting angle 8 is 00, the width of each tuning fork arm is wO, and the length of each tuning fork arm is lo. The abscissa represents
the thickess t of the vibrator, and the ordinate
represents the resonant frequency f. The
curves shown in Fig. 9 represent the resonant
frequencies of the first overtone vibration of the flexural mode of vibration and the funda
mental vibration of the torsional mode of
vibration.If the cutting angle, the width and
the length of the vibrator are respectively 80, w, and 1o without any dimensional error, the two curves show how the resonant frequen
cies of the first overtone vibration of the
flexural mode of vibration and the fundamen
tal vibration of the torsional mode of vibration vary with the change of the thickness. When the thickness is tot the first overtone vibration of the flexural mode of vibration has the
resonant frequency of a point A and the fundamental vibration of the torsional mode of vibration has the resonant frequency of a
point B.At this thickness, the resonant fre
quency-temperature characteristic which is shown by the curve 7 in Fig. 6 is obtained, and the resonant frequency of the first overtone vibration of the flexural mode of vibration has a specified value. Namely, when the -eut- ting angle, the thickness, the width and the
length are respectively 00, to, Wo and 1o the vibrator is an acceptable finished article in which there is no necessity to adjust the resonant frequency and the resonant frequency-temperature characteristic.However, when the cutting angle, the thickness, the width and the length deviate from Sot to, w0 and 1o due to variations of dimensions which occur in mass production and to the limits of processing accuracy, the resonant frequencies of the first overtone vibration of the flexural mode of vibration and of the fundamental vibration of the torsional mode of vibration respectively shift to the points C and D. The resonant frequency-temperature characteristic differs from that shown by 7 in Fig. 6, due to the deviation of the cutting angle and the external dimensions from the most suitable values, and to the fact that the oscillation frequency also deviates from the specified value.It is necessary to make the resonant frequency of the point C coincide with that of the point A and the resonant frequency of the point D with that of the point B by some method in order to remove such deviations.
Thus, the resonant frequency-temperature characteristic almost coincides with that of a vibrator having the most suitable cutting angle, thickness, width and length if one makes the deviating resonant frequencies of the first overtone vibration of the flexural mode of vibration and the fundamental vibration of the torsional mode of vibration coincide with the most suitable values thereof. The oscillation frequency will in this case also coincide with the specified value.
The following is a method to make the resonant frequencies at C and D coincide with the most suitable frequencies at A and B.
If the differences between the actual values and the most suitable values of the respective
resonant frequencies of the first overtone vi
bration of the flexural mode of vibration and the fundamental vibration of the torsional
mode of vibration are AfF and AfT, then Fig.
10 indicates the position where the weight should be added on the tuning fork vibrator and the value of AfF/AfT. The abscissa respresents the distance I in the longitudinal direction of the tuning fork vibrator where the
nodal point of the first overtone vibration of the flexural mode of vibration is 0 and the end of the tuning fork vibrator is 1. The ordinate is the ratio of AfF to AfT. The ratio of -the change of the respective resonant frequencies -with respect to the position where the fixed weight is added is shown in Fig. 10.
The ratio of the change of resonant frequency is almost proportional to the square root of the ratio of amplitude. That is to say, the position where the weight should be added is determined by measuring aft and AfT.
Fig. 11 shows a device for effecting the frequency adjustment. 14 is a vacuum chamber, 1 5 is a deposition source, the deposition being made in the direction of an arrow 16, 1 7 is a shutter, 18 is a slit plate having slits
19. The slit plate 1 8 is connected to a screw 21 and a pulse motor 22 so that it can be moved parallel to a mode coupled tuning fork type quartz crystal vibrator 20.
The tuning fork vibrator 20 is set up in the vacuum chamber 14. A resonance circuit 23 measures the resonant frequencies fF and fT of the first overtone vibration of the flexural mode of vibration and of the fundamental vibration of the torsional mode of vibration respectively. A comparative operational circuit 24 measures the differences AfT and AfF between the measured resonant frequencies, fT and fF, and the desired resonant frequencies, fTO and fFO. Then, the position where the weights are to be added is calculated by determining AF/Afr. The result of the calculation is applied to a drive circuit 25 for the pulse motor 22, and the pulse motor 22 is rotated thereby.This rotation is transmitted by transmission gears 22' and 21' to move the screw 21 or operating the slit plate 18, whereby the position of the slit plate 18, and consequently the position of the slits 1 9 are determined. The shutter 1 7 is then opened, and the deposition is started. When the resonant frequency fp of the first overtone vibration of the flexural mode of vibration (which may constitute the main mode of vibration) reaches the desired value fFO, the shutter 1 7 is closed. Thus, the frequency adjustment is finished. As for AfF/fFo and AfT/fTo after the frequency adjustment, 60 ppm or less and 600 ppm or less are respectively acceptable.
The above-mentioned frequency adjustment is for a standardized tuning fork type quartz crystal vibrator.
In the case where the accuracy is to be further improved or the tuning fork is imperfectly shaped, the frequency adjustment is performed twice. For example, 80 percent of AfF is adjusted at the first time. ff and fT are then measured again, the position where the weights are added is altered according the calculation, and then the frequency is adjusted for the second time. The frequency adjustment may be also performed by effecting measuremnets of fF and fit at all times with an instrument such as a spectro-analyzer and feeding back to the pulse motor 22, and hence to the slits 19, the information of the position where the weights are to be added, such information being calculated on the basis of the said measurements.
Thus, as mentioned above, a mode coupled tuning fork type quartz crystal vibrator of low power consumption and highly accurate frequency-temperature characteristic can be adjusted to have a desired frequency-temperature characteristic at a low price.
Although in the Fig. 8 embodiment silver is deposited as a weight by evaporation, the weight may be added by sputtering. Any material will do for the weights provided that the material is suitable for evaporation or sputtering.
Claims (11)
1. A method of adjusting a frequency of vibration of a tuning fork type piezo-electric vibrator which, in operation vibrates in coupled modes, the said method comprising adjusting the weight of at least one portion of the vibrator, the position of the or each said portion being selected in dependence upon the frequencies of said modes.
2. A method as claimed in claim 1 in which the said position is selected in dependence upon the extents to which the frequencies of said modes differ from predetermined values thereof.
3. A method as claimed in claim 2 in which the said position depends upon the ratio of the differences between the actual frequencies of the two modes and predetermined frequencies thereof.
4. A method as claimed in any preceding claim in which the weight of the or each said portion is adjusted by depositing material thereon.
5. A method as claimed in claim 4 in which the deposition of the material is continued until the frequency of one of said modes has a predetermined value.
6. A method as claimed in claim 5 in which the predetermined value of the said mode is not the final desired value thereof, and, after the predetermined value has been achieved, the method according to any preceding claim is repeated so that the frequency of the said mode reaches the final desired value.
7. A method as claimed in claim 4 and in claim 6 in which the repetition of the method involves the deposition of material at at least one position which differs from that at which the material was orginally deposited.
8. A method as claimed in any preceding claim in which a slit plate is mounted for movement parallel to the vibrator, the slit plate being interposed between a deposition source and the vibrator, and there being means for moving the slit plate in dependence upon the frequencies of said modes.
9. A method as claimed in claim 8 in which a shutter is interposed between the slit plate and the vibrator.
10. A method as claimed in claim 8 or 9 in which the slit plate, deposition source and vibrator are mounted in a vacuum chamber.
11. A method as claimed in any preceding claim in which the modes are flexural or torsional modes.
1 2. A method as claimed in any preceding claim in which the first overtone of the flexural mode is coupled to the fundamental vibration of the torsional mode.
1 3. A method as claimed in any preceding claim in which a main mode of vibration is coupled to a secondary mode thereof, the frequency of the main mode being adjusted by the adjustment of the weight.
1 4. A method of adjusting a frequency of vibration of a tuning fork type piezo-electric vibrator substantially as hereinbefore described with reference to Fig. 11 of the accompanying drawings.
1 5. A tuning fork type pieze-electric vibrator when made by the method claimed in any preceding claim.
1 6. A vibrator as claimed in claim 14 and substantially as hereinbefore described with reference to and as shown in Fig. 8.
1 7. Frequency adjustment of a tuning fork type quartz crystal vibrator in which the main mode of vibration and the secondary mode of vibration existing within said vibrator are coupled being characterised in that a weight on a position calculated on the basis of deviation of frequencies of said main mode of vibration and said secondary mode of vibration from desired values thereof is increased or decreased.
1 8. Frequency adjustment of a tuning fork type quartz crystal vibrator in which the main mode of vibration and the secondary mode of vibration existing within said vibrator are coupled being characterised in that a position where a weight is increased or decreased is controlled to adjust frequencies of said main mode of vibration and said secondary mode of vibration to respective desired values.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP16377278A JPS5591223A (en) | 1978-12-28 | 1978-12-28 | Frequency control method for tuning fork oscillator |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2044526A true GB2044526A (en) | 1980-10-15 |
Family
ID=15780416
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7943144A Withdrawn GB2044526A (en) | 1978-12-28 | 1979-12-14 | Method of adjusting a frequency of vibration of a tuning fork type piezo-electric vibrator |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS5591223A (en) |
| DE (1) | DE2951241A1 (en) |
| FR (1) | FR2445656A1 (en) |
| GB (1) | GB2044526A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE4101519A1 (en) * | 1991-01-19 | 1992-07-23 | Vdo Schindling | Tuning fork quartz for portable clock or wrist watch - has temp. reversal point in excess of 25 deg. C. and heater with temp. control |
-
1978
- 1978-12-28 JP JP16377278A patent/JPS5591223A/en active Pending
-
1979
- 1979-12-14 GB GB7943144A patent/GB2044526A/en not_active Withdrawn
- 1979-12-19 DE DE19792951241 patent/DE2951241A1/en not_active Withdrawn
- 1979-12-27 FR FR7931777A patent/FR2445656A1/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5591223A (en) | 1980-07-10 |
| DE2951241A1 (en) | 1980-07-17 |
| FR2445656A1 (en) | 1980-07-25 |
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