JPH06164285A - Manufacture of thickness-shear crystal vibrator - Google Patents

Abstract

PURPOSE:To manufacture a thickness-shear crystal vibrator remarkably small and having stable principal vibration characteristic easily and with high production efficiency. CONSTITUTION:An ordinary AT cut crystal master plate 22 provided with coordinates(X, Y', Z') in which X'-axis and Y'-axis are set by rotating Y-axis and Z-axis by about 35 deg. around the X-axis of crystal is used, and thickness can be uniformalized along the Z'-axis and it can be thinned as advancing from a center part to both terminal parts by applying cylindrical surface working to the plane on one side of the crystal master plate 22 along the direction of Z'-axis. Thence, X''-axis and Z''-axis are set by rotating the X-axis and Z'-axis by an angle (phi) (phi=3-30 deg.) around the Y'-axis, and the crystal master plate is divided into plural pieces along a cut plane set so as to be parallel with the X''-axis and also to incline by a prescribed angle (zeta) in the direction of Z''-axis for the plane of X''-axis-Y'-axis. In such a case, the angle (phi) is set at about 15 deg., and correspondingly, the angle (zeta) is set at about 5 deg..

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a crystal unit that vibrates in thickness shear.

[0002]

2. Description of the Related Art Conventionally, there has been a disk-shaped AT-cut crystal resonator as a crystal resonator that causes thickness shear vibration. This AT-cut crystal oscillator is widely used because of its excellent frequency-temperature characteristics, but it has a drawback that it is difficult to miniaturize it.

A rectangular AT-cut crystal oscillator has also been proposed. However, even in this case, when the crystal unit is downsized to reduce the width-thickness ratio of the crystal element, that is, the side ratio, the main vibration level is lowered and the number and level of unnecessary vibrations are increased, and the main vibration characteristics are It fell and was not suitable for practical use.

Further, a rectangular AT-cut crystal resonator in which the side surface of the crystal piece is inclined by about 5 degrees has been proposed. This is intended to prevent the main vibration characteristic from being deteriorated by reducing the coupling with the contour system vibration. However, even in this crystal unit, the main vibration level is lowered as the size is reduced. The drawbacks were not eliminated.

As described above, it has heretofore been difficult to manufacture a crystal unit that can be miniaturized without deteriorating the main vibration characteristic by any of the methods.

[0006]

It is an object of the present invention to allow a thickness-sliding quartz crystal resonator, which can be extremely miniaturized without lowering the main vibration level, and an unnecessary vibration group of a contour system, to be kept away from the main vibration region. An object of the present invention is to provide a method for easily and efficiently manufacturing a thickness-sliding quartz crystal resonator that can oscillate stably with main vibration.

[0007]

In order to achieve the above object, according to the present invention, the X axis of the crystal and the Y axis with the X axis as the center.
A rectangular shape in which each piece is formed along a Y'axis set by rotating the axis about 35 degrees in the Z-axis direction and a Z'axis set by rotating in the same manner as the Y'axis. Using an AT-cut quartz crystal blank, the quartz crystal blank is processed to have a uniform thickness along the Z′-axis direction and become thinner along the X-axis direction from the center to both ends. ,
The X ″ axis and the Z ″ axis are set by rotating the X axis and the Z axis about the Y ′ axis by a predetermined angle φ, respectively, and the Z ″ axis and the Z ″ axis are parallel to the X ″ axis direction and Z ′ with respect to the X ″ axis-Y ′ axis plane. It is characterized in that the original quartz plate is divided into a plurality of pieces along a cutting surface set to be inclined by a predetermined angle ζ in the axial direction.

The angle φ is set within the range of 3 degrees to 30 degrees, and the angle ζ is determined in correspondence with the angle φ.

[0009]

The rod-shaped thickness-sliding quartz crystal oscillator manufactured according to the present invention is stable even if it is made smaller than the conventional one, because the coupling with the vibration of the contour system can be loosened and the resonance level of the main vibration becomes high. It can oscillate.

[0010]

EXAMPLES Examples of the present invention will be described below. First, the thickness-sliding quartz crystal resonator manufactured by the method of the present invention will be described. The X axis, Y axis, and Z axis shown in FIG. 1 are the electric axis, mechanical axis, and optical axis of the crystal, respectively. Here, the coordinate axes of the AT-cut quartz crystal original plate used in the present invention are the Y ′ axis set by rotating the Y axis in the Z axis direction by an angle θ with the X axis as the center, and the Z axis in the same direction. The Z'axis is set by rotating by θ. This angle θ is about 3
It is 5 degrees.

In the present invention, further rotated coordinate axes are set based on the coordinate axes (X, Y ', Z') of such an AT-cut crystal original plate. That is, with the Y'axis as the center,
The X ″ axis is set by rotating the X axis in the Z ′ axis direction by an angle φ, and the Z ″ axis is set by rotating the Z ′ axis in the same direction by an angle φ. The angle φ is set in the range of 3 degrees to 30 degrees.

1 to 5 show a crystal piece 1 manufactured by the manufacturing method according to the present invention. In the following examples, the length L is about 6 mm, the width w is about 1 mm, and the thickness t.
Is about 0.4 mm and the side ratio (width w / thickness t) is 2.5.

In the crystal piece 1, the longitudinal direction thereof coincides with the X "axis direction, the main surface 1b is formed parallel to the X" axis-Z "plane, and the other main surface 1a is X". It is formed into a convex curved surface in the Y′-axis direction from a plane parallel to the axis −Z ″ plane. That is, one main surface 1a of the crystal blank 1 is a part of a side surface of a cylinder parallel to the Z ′ axis. Thus, the main surface 1a has a uniform thickness along the Z'-axis direction, and has a thick central portion at both end portions along the X "-axis direction. It has a cylindrical shape that becomes thinner as it goes. And the longitudinal side surface 1
c and 1d are inclined in the Z ″ direction by an angle ζ with respect to the X ″ -axis-Y ′ axis plane. In the present invention, the angle ζ is determined from the relationship of FIG. 6 based on the angle φ within the range of 1 degree to 6 degrees. The end faces 1e and 1f of the crystal blank 1 are processed so as to be parallel to the Y'axis-Z "axis plane. As shown in FIGS. 3 and 5, cylindrical surface processing is performed in the Z'axis direction. In the end faces 1e and 1f, the thickness changes.

7 to 9 show a manufacturing process of the above crystal piece. First, a normal AT-cut crystal original plate 22 cut out from a crystal at a cutting angle of about 35 degrees is prepared.
Then, on one surface of this AT-cut crystal original plate 22, Z '
After the cylindrical surface is machined along the axial direction, it is cut obliquely at angles φ and ζ. The crystal piece 21 cut in this manner has its longitudinal direction aligned with the X ″ axis obtained by rotating the X axis in the Z ′ axis direction by an angle φ, and one main surface 21a is formed by the above cylindrical surface processing. , Z ′ axis has a uniform thickness, and the thickness decreases from the central portion toward both ends along the X axis. 21c, 21
d is inclined by an angle ζ in the Z ″ -axis direction with respect to the X ″ -axis-Y′-axis plane. The end faces 21e and 21f are parallel to the Y'axis-Z'axis plane. In this embodiment, the angle φ is about 15 degrees, and the angle ζ is set to about 5 degrees based on the relationship shown in FIG. When the crystal blank 21 is manufactured in this manner, an AT that is usually commercially available
A large number of crystal pieces 21 can be easily obtained from the cut crystal original plate, and the production efficiency is good.

The end faces 21e, 21f of the crystal piece 21 thus obtained can be made parallel to the Z ″ axis by polishing or the like.
The crystal piece has the same shape as that of (1), and the side surface in the longitudinal direction and the side surface in the width direction are orthogonal to each other, which simplifies the holding structure.

In the crystal piece 21 of the above embodiment,
Cylindrical surface processing can be applied to both main surfaces. Then, the thickness of both ends can be further reduced.
In this case, it is necessary to increase the radius of curvature when machining the cylindrical surface.

FIGS. 10 to 13 show a third crystal piece according to the present invention.
Shows an example of. The crystal piece 31 has a larger side ratio w / t than in the above example, and the angle φ is set to about 10 degrees and the angle ζ is set to about 5.1 degrees. Then, it is formed by performing bevel processing for processing both sides of the crystal element into inclined surfaces along the Z ′ axis. As a result, the crystal piece 31 has a uniform thickness along the Z ′ axis, and both end portions have a thickness that decreases toward the edge along the X axis. The crystal piece 31 has its longitudinal direction aligned with the X ″ -axis direction, and both ends of the principal surfaces 31a and 31b are beveled. The side surfaces 31c and 31d in the longitudinal direction have X ″ -axis-Y ′. The end surface 31 is inclined with respect to the axial plane in the Z ″ -axis direction by an angle ζ.
e and 31f are processed so as to be parallel to the Y′-axis-Z ″ -axis plane. The beveling may be performed on only one of the main surfaces. The end surfaces are Y′-axis-Z ′. It may remain parallel to the axial plane.

14 to 17 show a fourth embodiment of the present invention. In manufacturing the crystal piece 41, the X ″ axis is set by rotating the X axis in the direction opposite to the Z ′ axis by an angle φ about the Y axis, and the Z axis is rotated in the same direction by an angle φ. Z ″ axis is set. In this example,
The angle φ is set to about 5 degrees and the angle ζ is set to slightly more than 5 degrees. Then, along the Z ″ axis, both main surfaces 41a of the crystal piece 41,
41b is bicylindrical processed. As a result, the crystal piece 41 has a uniform thickness along the Z ″ axis and is formed thinner along the X ″ axis from the center to both ends. The longitudinal side surfaces 41c and 41d are inclined with respect to the X "-axis-Y'-axis plane in the Z" -axis direction by an angle ζ. The end faces 41e and 41f are processed so as to be parallel to the Y′-axis-Z ″ -axis plane.

Since quartz belongs to the trigonal system, the X ″ axis,
When the Z ″ axis is set, the same effect can be obtained by rotating the X axis and the Z ′ axis to either side within the range of 3 to 30 degrees around the Y axis.

The crystal piece according to the present invention is formed as described above. Next, this driving method will be described with reference to FIGS.

Driving electrodes 12 and 13 are respectively formed on the central portions of both main surfaces 11a and 11b of the crystal blank 11 by vapor deposition or the like. From the driving electrodes 12 and 13, the extraction electrode 1 is formed.
2a and 13a are extended to the end of the crystal piece 11. When an electric field is applied to the drive electrodes, the crystal blank 11 oscillates. This driving method is the same for all the crystal pieces in the first to fourth embodiments.

The applicant has conducted experiments under various conditions. First, FIG. 20 and FIG.
This will be described with reference to FIG. In these experiments,
In the same manner as the crystal piece 11 shown in the embodiment of FIG.
A crystal piece having a thickness of about 6 mm and a thickness t of about 0.4 mm was formed by cylindrically processing one main surface of the crystal piece.

As a first experiment, the resonance frequency of the above crystal piece formed under the conditions of angle φ = about 15 degrees and angle ζ = about 5 degrees was measured. The relationship between the width w of the crystal piece and the resonance frequency is shown in FIG. In this graph, x indicates the main vibration, and the size of ◯ overlapping this x indicates the height of the resonance level. Other circles indicate secondary vibration,
Vibrations with low resonance levels are indicated by dots. From these results, it can be seen that the resonance level of the main vibration is very high and the sub-vibrations close to the main vibration are small and the best vibration characteristics are exhibited in the widths w near 1 mm and around 1.35 mm. However, the width w is 1.
Those smaller than 55 mm generally show good vibration characteristics.

In the second experiment, the angle φ = about 30
The resonance frequency of the above-mentioned crystal piece formed under the condition of the angle and angle ζ = about 4.5 degrees was measured. The relationship between the width w of the crystal piece and the resonance frequency is shown in FIG. 21, and the symbols in the graph are the same as those shown in FIG. According to this, when the width w is in the range of about 0.95 mm to 1.35 mm, the resonance level of the main vibration is high, the secondary vibration close to the main vibration is small, and the vibration characteristics are excellent. Especially, it is remarkable at 1.25 mm or less.

The applicant of the present invention conducted experiments under various conditions other than the above first and second experiments. Next, from FIG.
The experiment shown in 28 will be described. In these graphs, the vertical axis represents the size of the resonance level and the horizontal axis represents the frequency.

FIG. 22 shows the measurement result of the resonance level when the width w is set to about 1.00 mm in the conventional crystal oscillator, that is, the one in which the angle φ is 0 degree. According to this, although the resonance level of the main vibration A is sufficiently high, the resonance level of the sub-vibration B having a frequency close to the main vibration is large and is not suitable for practical use.

23 to 27, the angle φ is 5 °, 10 °, 1
It shows the respective measurement results when the width w was set to about 1.00 mm for the crystal oscillators of 5 degrees, 30 degrees, and 45 degrees. It can be seen that all of them have a sufficiently high resonance level of the main vibration A, and there is almost no sub-vibration having a frequency close to this main vibration, which is suitable for practical use. When φ = about 30 degrees shown in FIG. 28, a slightly larger auxiliary vibration B is seen, but since this is also away from the main vibration A, it is considered that there is no problem in practical use.

Then, FIG. 28 shows the measurement results for the crystal unit having an angle φ of 60 degrees and a width of about 1.00 mm. Although the resonance level of the main vibration A is high, the resonance level of the sub-vibration B adjacent thereto is large, which is not suitable for practical use.

Next, the graph shown in FIG. 29 will be described. This graph shows that the length L is about 5.90 mm, the width w is about 1.00 mm, and the angles φ are 0 degrees, 5 degrees, 10 degrees, and 15 degrees.
The results of measuring the crystal impedance (hereinafter referred to as "CI value") of the crystal oscillators of 30 degrees, 30 degrees, and 45 degrees are shown. Since there were variations in the measured values, the area near the center is indicated by a circle, and the range of variation is indicated by a solid line. Further, as a comparative example, a CI value and a range of its variation of a crystal resonator conventionally used for practical use, that is, a crystal resonator having a width w of about 1.67 mm and an angle φ of 0 degree are shown by Δ and a broken line. There is. The CI value decreases as the main vibration level increases, and the smaller the value, the more suitable it is for practical use.

As is clear from this graph, in the conventional crystal unit having the angle φ of 0 degree, the width w is 1.6.
The size of about 7 mm had a sufficiently low CI value and was suitable for practical use, but when the width w was as small as about 1.00 mm, C
Since the I value was too high to be used, the crystal unit could not be miniaturized. On the other hand, the angle φ is 5 degrees, 10
Degrees of 15 degrees and 30 degrees have a small CI value and are sufficiently suitable for practical use even if the width w is around 1.00 mm. However, it was found that the one having an angle φ of 45 degrees had a high CI value and was not suitable for practical use.

As described above, when the measurement results shown in FIGS. 22 to 28 and the measurement results shown in FIG. 29 are combined and the experimental error and variations are taken into consideration, the angle φ of the crystal oscillator is about 3 to 30 degrees. When it is within the range, it can be determined that the width w can be reduced to about 1.00 mm.

From the points of resonance level of the main vibration and the number and level of the sub vibrations, the optimum combination of the angle φ and the angle ζ for practical use is experimentally obtained and plotted in the graph in FIG.
Is. From this graph, the angle φ is 3 degrees as described above.
It can be seen that the angle ζ when in the range of 30 degrees is in the range of 1 degree to 6 degrees. Note that the range of the angle ζ is about 5 degrees, which is almost the same as the conventional product.

As described above, the crystal oscillator in the range of the angle φ = 3 to 30 degrees has a high resonance level of the main vibration, few secondary vibrations close to the main vibration, and a low CI value, and is practically used. It became clear that it had sufficient performance.

The angle θ in the present invention is in the range of 34 to 36 degrees, and the angle ζ is in the range of 1 to 6 degrees, as in the case of the conventional AT-cut crystal original plate.

As described above, according to the present invention, a crystal resonator having a small side ratio and excellent main vibration characteristics can be obtained. Therefore,
Even if the width of the crystal unit is reduced, the main vibration characteristic does not deteriorate, so that the crystal unit can be made smaller than the conventional one.

[0036]

As described above, according to the present invention, it is possible to easily and easily produce a thickness-sliding quartz crystal resonator which is extremely small in size and which can eliminate unnecessary vibrations from the main vibration region and stabilize the main vibration characteristics. It can be manufactured efficiently. The thickness-slipped quartz crystal resonator can stably oscillate even if the manufacturing tolerance is increased.

[Brief description of drawings]

FIG. 1 is a perspective view showing a crystal piece manufactured by a method according to the present invention.

FIG. 2 is a front view of the crystal piece shown in FIG.

FIG. 3 is a side view of the crystal piece shown in FIG.

4 is a bottom view of the crystal piece shown in FIG. 1. FIG.

5 is a view taken along the line SS in FIG.

FIG. 6 is a graph showing the relationship between angle φ and angle ζ.

FIG. 7 is an explanatory view showing a method for manufacturing a crystal piece according to the present invention.

8 is a side view of a crystal piece manufactured by the method shown in FIG.

9 is a view taken along the line TT of FIG.

FIG. 10 is a front view of another embodiment of the crystal piece.

11 is a side view of the crystal piece shown in FIG.

FIG. 12 is a bottom view of the crystal piece shown in FIG.

13 is a view taken along the line UU of FIG.

FIG. 14 is a front view of still another embodiment of the crystal piece.

FIG. 15 is a side view of the crystal piece shown in FIG.

16 is a bottom view of the crystal piece shown in FIG.

FIG. 17 is a view taken along the line VV of FIG.

FIG. 18 is a front view of a crystal unit in which drive electrodes are formed on a crystal piece.

19 is a rear view of the crystal unit shown in FIG.

FIG. 20 is a relationship diagram between the width and the resonance frequency of a crystal unit with an angle φ of about 15 degrees.

FIG. 21 is a diagram showing the relationship between the width and the resonance frequency of another crystal unit having an angle φ of about 30 degrees.

FIG. 22 is a diagram showing the relationship between the resonance level and the frequency of a crystal unit with an angle φ = 0 degree.

FIG. 23 is a relationship diagram between a resonance level and a frequency of a crystal unit with an angle φ = 5 degrees.

FIG. 24 is a relationship diagram between a resonance level and a frequency of a crystal unit with an angle φ = 10 degrees.

FIG. 25 is a relationship diagram between a resonance level and a frequency of a crystal unit with an angle φ = 15 degrees.

FIG. 26 is a relationship diagram between the resonance level and the frequency of the crystal unit with an angle φ = 30 degrees.

FIG. 27 is a relationship diagram between the resonance level and the frequency of a crystal unit with an angle φ = 45 degrees.

FIG. 28 is a diagram showing the relationship between the resonance level and the frequency of a crystal unit with an angle φ = 60 degrees.

FIG. 29 is a relationship diagram between the crystal unit angle φ and the CI value.

[Explanation of symbols]

1, 11, 21, 31, 41 ... Crystal pieces 11a, 11b, 21a, 21b, 31a, 31b, 4
1a, 41b ... Main surfaces 11c, 11d, 21c, 21d, 31c, 31d, 4
1c, 41d ... Side surface (cut surface) 22 ... AT-cut crystal original plate θ, φ, ζ ... Angle t ... Thickness w ... Width

Claims (2)

[Claims] 1. An X-axis of a crystal and Y around the X-axis.
A rectangular shape in which each piece is formed along a Y'axis set by rotating the axis about 35 degrees in the Z-axis direction and a Z'axis set by rotating in the same manner as the Y'axis. Using an AT-cut crystal original plate, the crystal original plate is processed to have a uniform thickness along the Z′-axis direction and become thinner along the X-axis direction from the center to both ends, In the above-mentioned crystal original plate, the above-mentioned X centering around the above Y'axis
Axis and the Z axis are respectively rotated by a predetermined angle φ to set the X ″ axis and the Z ″ axis, which are parallel to the X ″ axis direction and predetermined in the Z ″ axis direction with respect to the X ″ axis-Y ′ axis plane. A method of manufacturing a thickness-sliding quartz crystal resonator, characterized in that the above-mentioned quartz original plate is divided into a plurality of pieces along a cutting plane set so as to be inclined by an angle ζ. 2. The thickness slip according to claim 1, wherein the angle φ is set within a range of 3 degrees to 30 degrees, and the angle ζ is determined corresponding to the angle φ. Crystal oscillator manufacturing method.