JPS59128422A - Crystal thermometer - Google Patents

Abstract

PURPOSE:To obtain a highly accurate crystal thermoemeter, by using a pair of crystal vibrators, which are cut out within a specified angle range of a crystal wafer that is cut out in a specified rotary angle range, thereby reducing temperature calibrating points. CONSTITUTION:A crystal wafer is cut out in a rotary angle range of 20 deg.-160 deg. with respect to an axis X or Y. A oair of crystal vibrators 1 and 2 are cut out in a cut out range of + or -60 deg.-+ or -120 deg. in the crystal wafer W and formed. One of the pair of the vibrators 1 and 2 is used as a temperature measuring element, and the other is used as a reference locking element. Then, the temperature coef ficient characteristics are canclelled to each other out, temperature calibrating points are decreased, and a highly accurate crystal thermometer is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a crystal thermometer using a crystal resonator as a temperature measuring element. More specifically, the present invention has two crystal oscillators made of the same crystal Ueno 1, one of which is used as a temperature measuring element, and the other oscillator is used as an oscillation element for obtaining a reference clock. This relates to a crystal thermometer.

Since quartz crystal has crystal anisotropy, by appropriately selecting the cutting angle, the temperature coefficient can be reduced to zero, or conversely, the temperature coefficient can be increased.

You can also A crystal thermometer uses a crystal resonator with a large temperature coefficient as a temperature measuring element, and has features such as high resolution, high stability, and 9-frequency output.

In conventional crystal thermometers of this type, the crystal oscillator as the temperature measuring element and the crystal oscillator for obtaining the reference clock are constructed completely separately, so many temperature calibration points are required. It took a lot of effort to proofread it.

The present invention has been made in view of this point, and its purpose is to reduce the number of temperature calibration points and provide a highly accurate crystal thermometer.

The device according to the present invention has a rotation angle of 2 on the Y axis or on the Y axis.
On a crystal wafer cut out in the range of 0° to 160°,
A pair of crystal oscillators were made at an angle of ±60° to ±120°9, and one crystal oscillator was used as a temperature measuring element, and the other crystal oscillator was used as a crystal oscillator to obtain a total reference clock. The points are distinctive.

FIG. 1 is an electrical block diagram showing an example of a crystal thermometer according to the present invention. In this figure, 1 is a first crystal resonator, which serves as a temperature measuring element. This crystal oscillator 1 is not shown, but in order to quickly transfer heat,
It is installed in a metal case with high thermal conductivity that is filled with an inert gas such as helium gas.

2 is a second crystal oscillator, which is used to obtain a reference clock. 31 and 32 are amplifiers, which respectively connect the first crystal oscillator 1. An oscillation circuit os together with a second crystal resonator 2,
, os2, and each oscillation circuit os4.
os2 to oscillation frequency signal f1. f2 is served.

40 is a gate circuit that inputs the oscillation frequency signal f from the oscillation circuit OS (and the oscillation frequency signal f2 from the oscillation circuit O82), 5 is a counter, and 6 is an arithmetic display circuit that inputs the signal from the counter 5.

FIGS. 2 and 4 are explanatory diagrams for explaining how to make the first crystal oscillator 1 and the second crystal oscillator 2. FIG.

As shown in Fig. 2, a crystal resonator is made from a crystal unit/% cut by varying the rotation angle α with respect to the Y-axis (or Y-axis), and its temperature characteristics are determined as shown in Fig. 3. The total number will be 9. In Figure 3, the vertical axis is the change in resonance frequency Δf/f
shows.

First, in the present invention, in FIG.
The rotation angle α with respect to the axis) is in the range of 20° to 160°, that is, the range in which the temperature coefficient becomes large (Δf/f is −2
A crystal wafer W cut at a temperature of 0 ppm/° C. or higher is used.

Next, as shown in FIG. 4, a pair of crystal oscillators 1 and 2 are placed on this crystal wafer W so that their cut surfaces form an angle of θ to each other using, for example, photolithography technology.
Made using etching technology. Here, the crystal wafer W
Crystal bending oscillator 1 (for example, tuning fork oscillator) made on top
The first-order temperature coefficient for the cutting angle W (see FIG. 4) is as shown in FIG. 5. That is, when the cutting angle V is 0° (when cutting parallel to the Y axis), the temperature coefficient is the largest, whereas when V is around 90', the temperature coefficient is small and close to zero.

In the present invention, the bending oscillator l cut out near 1=0 is used as the first crystal oscillator that serves as a temperature measuring element, and V is around 90°, that is, the angle with respect to the bending oscillator 1. A bending oscillator 2 cut so that θ is at an angle of ±60° to ±12σ, preferably ±90°, is used as a second crystal oscillator for obtaining a reference clock.

The bending vibrator 1 and the bending vibrator 2 can be created using the same mask on the same crystal wafer cut out with the Y-axis or a rotation angle α of 20° to 160° with respect to the Y-axis. The angle θ can be made to be aligned with high precision.

The resonant frequency f of the bending vibrator l made in this way,
The characteristics of the resonant frequency f2 of the bending vibrator 2 with respect to temperature can be expressed by the fi1 equation and the equation (2).

t,′=,t,. (1+A, (T-To)10B, (T
-To)2+C4(T-To>5)...mx
2'=f2o(x+A2(T-To)+B2(T-To
) 2+C2(T-To)3) ・-(2+tap, f,." 20 'Resonance frequency A at temperature T.,
, A2. B,, B2. C,,C2: 1st order, 2nd order
Next.

With a third-order temperature coefficient, A2. B2゜C2Vi In this case, return to Figure 1. The oscillation circuit OS including the first crystal resonator 1
, outputs a temperature-related frequency f1,
Further, from the oscillation circuit O82 including the second crystal resonator 2, a frequency signal f2 (
reference clock signal) is output. The splitter 40 separates the frequency signal f, and applies it to the gate 4, which applies the frequency signal f2 to the counter 5 while the gate 4 is open. The counter 5 counts this signal, and its count value N is expressed by equation (3).

・・・・・・・・・・・・・・・・・・・・・・・・
・・・・・・・・・・・・・・・・・・・・・(3) However, t=(r-To) The calculation optical display circuit 6 inputs the count value from the counter 5,
From this, calculations for converting to temperature, calculations for linearization, etc. are performed, and the calculation results are displayed.

In a crystal thermometer with such a configuration, the first crystal oscillator 1 and the second oscillator 2 are made on the same crystal wafer in the same process using the same mask, and both crystal oscillators are cut out. The angle θ formed by the corners can always be maintained at an accurate value. Also, since both oscillators are obtained in the same process,
The influence of disturbances such as electrodes and dust layers can be made almost the same. Therefore, if only the cutting angle α of the crystal wafer W is determined accurately and f and /f2 are obtained,
The effects of various disturbances can be canceled, and highly accurate crystal temperature measurement with a small number of calibration points can be achieved.

In addition, in the above description, the crystal wafer W was first cut at a rotation angle α with respect to the May be used.

FIG. 6 is a diagram showing the first-order temperature coefficient with respect to the cutting angle da of a crystal bending vibrator manufactured on a crystal wafer rotated by β-50° with respect to the Y axis. In this case, a bending vibrator can be obtained that has a small temperature coefficient near γ-〇° and a large temperature coefficient near ri=90°. Therefore, it is preferable to use a bending vibrator cut out near 90° as a temperature measuring element, and a bending vibrator cut out near 1=O° to obtain a reference clock.

In the above description, the first crystal resonator 1 and the second crystal resonator 2 are bare and in the same shape on the same crystal wafer W at an angle of θ, as shown in FIG. Although it is assumed that the first and second crystal oscillators do not have the same shape, the first crystal oscillator 1 may include
A second crystal oscillator 2 may also be manufactured.

FIGS. 7 and 8 are explanatory diagrams showing an example of the shape of each crystal resonator in this case.

In the example shown in FIG. 7, the first crystal oscillator 1 is a tuning fork oscillator that vibrates as shown by the arrow, and the non-vibrating part of this crystal oscillator 1 has a smaller shape than the crystal oscillator in Series 1. Then, the second crystal resonator 2 is cut out so that the cutting direction forms an angle of θ=90° with respect to the cutting direction of the first crystal resonator.
It is composed of a tuning fork vibrator.

In the example of FIG. 8, the second vibrator 2 in FIG.
It is a vertical vibrator that vibrates as shown by the arrow.

In FIG. 1, an oscillation frequency signal f from the oscillation circuit OS and an oscillation frequency signal f2 from the oscillation circuit O82 are shown.
The configuration shown in the figure performs signal processing including calculations f, /'f2, but instead of this, f, , f2 are counted in colors, respectively, and
It may also be a circuit that applies digital signals from these counters to a microprocessor, performs predetermined calculations, and displays the temperature.

As described above, according to the present invention, a highly accurate crystal thermometer with fewer temperature calibration points can be realized.

[Brief explanation of the drawing]

FIG. 1 is an electrical block diagram showing an example of a crystal thermometer according to the present invention, FIGS. 2 and 4 are explanatory diagrams for explaining how to operate a second crystal resonator, 3, 5, and 6 are all diagrams showing the temperature characteristics with respect to the cutting angle, and FIGS. 7 and 8 are diagrams showing the temperature characteristics with respect to the cutting angle. FIG. 7 is an explanatory diagram showing an example of the shape of a second crystal resonator. 1... First crystal oscillator 2... Second crystal oscillator 31.32... Amplifier O81, O82... Oscillation circuit 40... Frequency divider 5... Counter 6・
...Calculation display circuit W...Crystal Ueno-Figure 5, tail 7, figure 6, figure 8

Claims (3)

[Claims] (1) A pair of crystal wafers are cut out from a crystal wafer 1 that is cut out at a rotation angle of 20° to 160° relative to the Y axis or the Y axis, and cut out so that the cutting angles are ±60° to ±120° to each other. A crystal thermometer constructed using a crystal oscillator, one crystal oscillator is used as a temperature measuring element, and the other crystal oscillator is used to obtain a reference clock. (2) The crystal thermometer according to claim 1, wherein the pair of crystal oscillators are formed using photolithography technology and etching technology. (3) The crystal thermometer according to claim 1, which is constructed by integrating a pair of crystal oscillators.