JP3980972B2 - Strip-shaped IT-cut crystal unit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an IT-cut quartz crystal resonator, and particularly to a holding position where good vibration characteristics can be obtained.
[0002]
[Prior art]
(Background of the Invention) Conventionally, as an example of a twice-rotated crystal resonator, an SC-cut crystal resonator as disclosed in Japanese Patent Application Laid-Open No. 11-177376 is known.
In this SC-cut crystal unit, for example, as shown in FIG. 4, the surface perpendicular to the Y-axis of the crystal is rotated about 33 ° around the X-axis, and from this rotated position around the Z-axis. The electrode is formed on the crystal piece 1 cut out from the surface rotated about 22 °.
[0003]
This SC-cut quartz crystal has a temperature characteristic of a cubic curve similar to that of the AT-cut, and its inflection point is 94 ° C., and is used as a quartz crystal of a so-called thermostatic crystal oscillator. .
[0004]
However, since the temperature of the inflection point is 94 ° C. in the SC-cut crystal resonator, the target temperature becomes 65 ° C. to 85 ° C. when the extreme value lower than this is set as the target temperature of the thermostatic bath.
For this reason, when an oscillator having a wide operating temperature range is required to use the high temperature side up to 80 ° C., for example, the margin with the set temperature of the thermostatic bath is reduced.
For this reason, it becomes difficult to control the thermostat to a constant temperature, and a constant oscillation frequency cannot be maintained.
[0005]
For this reason, it is considered to use an IT cut crystal resonator.
The IT-cut crystal resonator is a two-fold rotation crystal resonator similar to the SC-cut crystal resonator.
In the IT cut crystal resonator, for example, as shown in FIG. 5, the plane orthogonal to the Y axis of the crystal of the crystal is rotated by about 34 ° around the X axis, and further from this rotated position around the Z axis. An electrode is formed on a crystal piece 2 cut out from a surface rotated about 19 °.
[0006]
The temperature characteristics of this IT-cut quartz resonator are also similar to those of the SC-cut quartz resonator, and the inflection point temperature is as low as 74 ° C.
Therefore, the extreme value on the higher temperature side than the inflection point is 85 ° C. to 105 ° C.
Therefore, even when the maximum temperature of the operating temperature range is required to be 80 ° C., the set temperature of the thermostatic bath can be set in the range of 85 ° C. to 105 ° C., and temperature control can be performed relatively easily. .
[0007]
However, there are few practical examples of IT-cut quartz resonators, and the relationship between the support position and vibration characteristics has not been clarified at all.
[0008]
[Problems to be solved by the invention]
The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an IT-cut crystal resonator capable of obtaining good vibration characteristics by defining a support position.
[0009]
[Means for Solving the Problems]
According to the first aspect of the present invention, a plane orthogonal to the Y-axis of the crystal of the crystal is rotated about 34 ° around the X-axis, and cut from a plane rotated about 19 ° about the Z-axis from this rotated position. In this case, the crystal piece is a strip shape elongated in the Z′-axis direction, and holds the portions facing each other at 18 ° and 198 ° from the Z′-axis of the plate surface of the crystal piece. This is a strip-shaped IT-cut crystal resonator.
[0010]
According to the second aspect of the present invention, a plane orthogonal to the Y axis of the crystal of the crystal is rotated about 34 ° about the X axis, and the surface rotated about 19 ° about the Z axis from this rotated position. In the case where electrodes are formed on a strip-shaped quartz piece cut out from the above, the quartz piece is a strip that is elongated in the X′-axis direction, and is a portion of the quartz plate that faces each other at 108 ° and 288 ° from the Z′-axis. It is a strip-shaped IT-cut crystal resonator characterized by holding
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a plan view of a strip-shaped IT-cut crystal piece 3 elongated in the Z′-axis direction.
Such an IT-cut crystal piece rotates about 34 ° about the X axis about the plane perpendicular to the Y axis of the crystal of crystal, and further about 19 ° about the Z axis from this rotated position. It is cut out from the surface.
[0012]
In FIG. 1, the horizontal direction shown is the Z ′ axis, and the vertical direction is the X ′ axis.
Then, the portions of 18 ° ± 18 ° (shown A) and 198 ° ± 18 ° (shown B) from the Z′-axis of the plate surface of the crystal piece are held.
[0013]
The reason why the holding position of the crystal piece 1 is defined in this way is as follows.
That is, when the displacement distribution of the plate surface was measured when the piezoelectric vibration was excited in the IT-cut crystal piece, it was observed as shown in FIG.
In general, in a quartz resonator, it is desirable to hold a portion with little displacement in order to minimize the influence on the vibration characteristics.
[0014]
In FIG. 2, the horizontal direction is the Z ′ axis, and the vertical direction is the X ′ axis.
And the position and magnitude | size of a displacement are represented with the contour line.
Therefore, a relatively large displacement is located on a line connecting the directions of 160 ° and 340 ° from the Z ′ axis.
Therefore, avoiding this direction, hold the part of 18 ° ± 18 ° (shown A) from the Z ′ axis, more preferably 18 ° ± 9 ° and 198 ° ± 18 ° (shown B), more preferably 198 ° ± 9 °. It was decided to.
[0015]
In this way, it is possible to retain a portion with relatively little vibration displacement, and thereby obtain good vibration characteristics.
Further, the influence of the stress from the holding structure on the vibration characteristics can be reduced, and the stability can be improved.
[0016]
In the embodiment shown in FIG. 1, the description has been given of the case using the strip-shaped crystal piece 3 elongated in the Z′-axis direction. However, the present invention is not limited to this, and for example, as shown in FIG. 3. The present invention can also be applied to a crystal piece 4 elongated in the X′-axis direction.
In this case, the diagonal of the crystal piece is 108 ° ± 18 ° (shown C) from the Z ′ axis, more preferably 108 ° ± 9 ° and 288 ° ± 18 ° (shown D), more preferably 288 ° ± 9 °. What is necessary is just to hold | maintain the part located in.
[0017]
【The invention's effect】
As described in detail above, the present invention is designed to hold a portion with as little vibration displacement as possible, so that it is possible to reduce the influence of the holding system on the vibration characteristics without impairing the vibration characteristics, thereby being favorable. It is possible to provide an IT-cut crystal resonator capable of obtaining excellent vibration characteristics.
[Brief description of the drawings]
FIG. 1 is a plan view of a crystal piece according to an embodiment of the present invention.
FIG. 2 is a diagram showing a distribution of vibration displacement of an IT-cut crystal piece.
FIG. 3 is a plan view of a crystal piece according to another embodiment of the present invention.
FIG. 4 is a diagram for explaining a cutting angle of an SC-cut crystal piece.
FIG. 5 is a diagram for explaining a cutting angle of an IT-cut crystal piece.
[Explanation of symbols]
1, 2, 3, 4 crystal

Claims (2)

The surface of the quartz crystal perpendicular to the Y-axis is rotated about 34 ° around the X-axis, and the electrode is applied to the strip-shaped crystal piece cut out from the surface rotated about 19 ° around the Z-axis from this rotated position. The crystal piece is a strip shape elongated in the Z′-axis direction, and holds the portions of the plate surface of the crystal piece that face each other at 18 ° and 198 ° from the Z′-axis. IT cut crystal unit. The surface of the quartz crystal perpendicular to the Y-axis is rotated about 34 ° around the X-axis, and the electrode is applied to the strip-shaped crystal piece cut out from the surface rotated about 19 ° around the Z-axis from this rotated position. In which the crystal piece is a strip shape elongated in the X′-axis direction, and holds a portion of 108 ° and 288 ° facing each other from the Z ′ axis of the plate surface of the crystal piece. IT cut crystal unit.

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