JP2003243933A - Highly stable piezoelectric oscillator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly stable piezoelectric oscillator with high frequency stability, which can be downsized and a low height with excellent mass- productivity. <P>SOLUTION: In the piezoelectric oscillator wherein a printed circuit board with a piezoelectric vibrator, an oscillation circuit, a temperature sensing element, and a heater mounted thereon is contained in a package, the inside of the package is suctioned into a vacuum. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a high stability type piezoelectric oscillator, and it is possible to reduce the size and height of the high stability type piezoelectric oscillator while maintaining the stability of the oscillation frequency against the change of the ambient temperature. Concerning the structure of.

[0002]

2. Description of the Related Art High-stability crystal oscillators are widely used for measuring devices, mobile radio base stations, communication equipments mounted on satellites, etc. because of their excellent frequency accuracy, frequency temperature characteristics, frequency aging characteristics, etc. . In recent years, the demand has increased more and more, and high frequency stability is required.
In particular, base stations have been added due to the rapid increase in mobile phone subscribers,
The demand for highly stable oscillators used in base stations is also increasing.

As is well known, a crystal oscillator is widely used as a stable reference frequency transmission source. However, when a highly stable oscillation as described above is required, a constant temperature set to a temperature higher than room temperature is set. A relatively large thermostatic crystal oscillator in which a crystal oscillator is housed in a tank has been used.

For example, as shown in FIG. 6 disclosed in Japanese Utility Model Laid-Open No. 62-2811, a thermostatic chamber type crystal oscillator 1 that oscillates a highly stable frequency is a storage container (constant temperature) containing a crystal oscillator and its oscillation circuit. Bath 2), temperature sensing element 3 for measuring the internal temperature, and the constant temperature bath 2 based on the output of the temperature sensing element 3.
A heating element (heater) 4 that generates heat for keeping the internal temperature of the container at a constant temperature is enclosed in an inner container 5,
The inner container 5 is filled with an inert gas such as nitrogen or argon, the inner container 5 is covered with an outer container 6, and a vacuum is formed between the inner and outer containers.

With such a structure, the crystal oscillator and its oscillation circuit are provided in the temperature-controlled chamber 2 inside the thermostat 2.
Based on the temperature information detected by a thermistor (for example, a heater wire wound around the outer circumference of the thermostatic chamber 2) 4 and a heater control circuit (not shown), the frequency turnover of the crystal oscillator is performed. It is heated to the temperature (vertical temperature) and is controlled so as to always maintain the peak temperature.

Since a vacuum is formed between the outer container 6 and the inner container 5, heat conduction between the outer container 6 and the inner container 5 can be made extremely small due to the heat insulating effect of this portion. .

The temperature-controlled crystal oscillator 1 constructed as described above has a high frequency stability under any conditions such as an atmosphere, and is therefore effective as a reference frequency transmission source for measuring devices and communication equipment.

[0008]

By the way, in recent years, there is an increasing tendency toward downsizing of communication equipment, and there is a demand for downsizing and high profile of a highly stable oscillator provided for the communication equipment. However, the constant temperature chamber type crystal oscillator 1
Has a triple structure consisting of a constant temperature bath 2, an inner container 5, and an outer container 6, and is structurally large, and it is difficult to reduce the size and height of the container. Since the containers 5 must be tightly sealed so as to prevent vacuum leakage, mass productivity is low and there is a problem in cost reduction.

The present invention has been made in order to solve various problems relating to the above-described conventional constant temperature oven type crystal oscillator, and has high frequency stability and enables miniaturization and height reduction.
Another object of the present invention is to provide a highly stable piezoelectric oscillator excellent in mass productivity.

[0010]

SUMMARY OF THE INVENTION In order to solve the above problems, a high stability type piezoelectric oscillator according to the present invention has a piezoelectric vibrator, an oscillating circuit, a temperature sensitive element, and a heating element. A high-stability piezoelectric oscillator, wherein the inside of the container is a vacuum in a piezoelectric oscillator in which the printed circuit board is housed in a container.

According to a second aspect of the present invention, the printed circuit board is coated with a resin so as to cover at least the piezoelectric vibrator, the temperature sensitive element, and the heating element. It is an oscillator.

According to a third aspect of the present invention, in a piezoelectric oscillator in which a printed board on which a piezoelectric vibrator, an oscillation circuit, a temperature sensitive element, and a heating element are mounted is housed in a container, the container has a hollow wall. It is a highly stable piezoelectric oscillator characterized in that the inside of the hollow is a vacuum.

According to a fourth aspect of the present invention, the printed circuit board is coated with resin so as to cover at least the piezoelectric vibrator, the temperature sensitive element, and the heating element. It is an oscillator.

A fifth aspect of the present invention is the high-stability piezoelectric oscillator according to the third or fourth aspect, characterized in that the inside of the container is vacuum.

According to a sixth aspect of the present invention, in a piezoelectric oscillator in which a printed board on which a piezoelectric vibrator, an oscillation circuit, a temperature sensitive element, and a heating element are mounted is housed in a container including a base and a cover, the base and the cover are provided. Highly stable piezoelectric oscillators having a hollow structure and a vacuum inside.

According to a seventh aspect of the present invention, the printed circuit board is coated with a resin so as to cover at least the piezoelectric vibrator, the temperature sensitive element, and the heating element. It is an oscillator.

The invention according to claim 8 is the highly stable piezoelectric oscillator according to claim 6 or 7, characterized in that the inside of the container is vacuum.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below based on the illustrated embodiments. FIG. 1 is a sectional view showing the structure of a highly stable crystal oscillator according to a first embodiment of the present invention, in which a crystal resonator 8 and a temperature sensitive material are provided on the front and back surfaces of a printed circuit board 7 having excellent thermal conductivity. An element (thermistor) 9, a heating element (heater) 10, an oscillation circuit (not shown), a temperature control circuit (not shown) are mounted, and a lead terminal penetrating a hermetic glass portion provided with the printed circuit board 7 on a base 11. It is also mechanically supported by soldering to 12. Further, the base 11 and the metal cover 14 are hermetically sealed in a vacuum atmosphere so that the inside 13 of the container is evacuated to form a highly stable crystal oscillator 15.

As a result, the temperature change of the crystal unit is detected by the thermistor 9 via the printed circuit board 7, and the temperature control circuit operates the heater 10 based on the temperature information obtained as a result.
It is possible to heat the crystal oscillator 8 via the printed circuit board 7 by using, and control so that the turn-over temperature is always maintained. Since the printed circuit board 7 has a function of heat transfer, it is desirable that the printed circuit board 7 has excellent thermal conductivity.

Further, since the inside 13 of the container is evacuated, the influence of the temperature change in the external environment can be largely cut off.

Therefore, in contrast to the conventional thermostat-type crystal oscillator 1 shown in FIG. 6, the container has a triple structure, whereas the container of the highly stable crystal oscillator 15 has a base 11 and a metal cover 1.
Since the single seal structure composed of 4 is used, the size of the high stability type crystal oscillator can be reduced in size and height, and the mass production can be improved.

FIG. 2 is a sectional view showing the structure of a highly stable crystal oscillator 16 according to the second embodiment of the present invention.
In the high stability type crystal oscillator 15 of FIG. 1, the high stability type crystal oscillator 16 is configured by coating the printed circuit board 7 with the resin 17 so as to cover at least the crystal resonator 8, the thermistor 9 and the heater 10. Is.

In the structure of the high stability type crystal oscillator 15 shown in FIG.
Part of the heat generated by is lost as radiant heat. Therefore, by coating the printed circuit board 7 with the resin 17 as shown in FIG. 2, the loss of thermal energy due to radiant heat is absorbed by the resin 17, and the crystal unit 8, the thermistor 9, and the heater 10 are interposed via the resin 17. It is possible to transfer heat uniformly to and from. As a result, more stable temperature correction of the crystal unit can be performed, and thermal efficiency is significantly improved, so that power consumption can be reduced.

In order to minimize the temperature difference among the crystal unit 8, the thermistor 9, and the heater 10, it is desirable to use the resin 17 having excellent thermal conductivity.

Next, FIG. 3 is a sectional view showing the structure of a highly stable crystal oscillator 18 according to a third embodiment of the present invention, which is used for the highly stable crystal oscillator 15 shown in FIG. Instead of the metal cover 14 having a single plate structure, a metal cover 19 having a hollow structure and having a vacuum inside is used to hermetically seal the base 11.

By constructing a part of the container as a hollow wall as described above, since the metal cover 19 already has a heat insulating effect before the sealing step, the atmosphere in the container 20 is evacuated. It is not necessary to seal the atmosphere in the container as an inert gas atmosphere such as nitrogen or argon. Therefore, the sealing process is facilitated, and the sealing can be performed as in the conventional case, which facilitates the sealing. Further, the gas in the container 20 also functions as a heat retaining tank, so that the temperature stability is improved.

FIG. 4 is a sectional view showing the structure of a highly stable crystal oscillator 21 according to the fourth embodiment of the present invention.
As suggested in FIG. 2, in the high stability type crystal oscillator 18 of FIG. 3, a resin 17 is used to coat the printed circuit board 7 so as to cover at least the crystal oscillator 8, the thermistor 9 and the heater 10 to achieve high stability. Type crystal oscillator 21
Is configured.

As described with reference to FIG. 2, the resin 17 absorbs the loss of thermal energy due to radiant heat, and the absorbed energy loss is transmitted through the resin 17 to the crystal oscillator 8.
Since heat can be uniformly transferred to the thermistor 9 and the heater 10, more stable temperature correction of the crystal unit can be performed, and thermal efficiency is significantly improved, so that power consumption is reduced. It can also be converted.

Next, FIG. 5 is a sectional view showing the structure of a highly stable crystal oscillator 22 according to a fifth embodiment of the present invention, in which the hollow structure shown in FIG. 3 and the inside of the hollow are vacuum. For the highly stable crystal oscillator 18 using the metal cover 19,
Further, the base 23 also has a hollow structure and a vacuum inside. Therefore, the heat insulating effect can be further improved. Here, if the printed board 7 is coated with the resin 17 as described above, more stable temperature correction of the crystal unit can be performed, and
The thermal efficiency can be improved.

Further, in the embodiment shown in FIGS. 3 to 5, either or both of the metal cover and the base have a double structure, and the inside thereof is evacuated in advance, so that the stages of each component are different. If the vacuum inspection is performed, it is not necessary to inspect the vacuum leakage after the container is assembled, so that the number of manufacturing processes can be reduced and the non-defective product rate can be expected to be improved as compared with the case of FIG.

A double vacuum structure in which the atmosphere inside the container 24 of FIG. 5 is a vacuum may be adopted. By making the vacuum structure a double vacuum structure, it is possible to further improve the heat insulating effect and also obtain the effect of vacuum compensation when the vacuum atmosphere of one vacuum structure is deteriorated or broken.

[0032]

Since the highly stable piezoelectric oscillator according to the present invention is constructed as described below, it has the following excellent effects. According to the invention of claim 1, since the vacuum atmosphere structure inside the container is realized by the single seal structure, the container can be downsized and the height can be reduced, and the mass productivity can be improved.

The invention of claim 2 has an excellent effect that the container can be downsized and the height can be reduced, and the thermal efficiency related to the temperature correction of the crystal unit can be improved so that the power consumption can be reduced.

Furthermore, since the container has a single seal structure, it has an excellent effect that mass productivity can be improved.

According to the third aspect of the invention, since the container has a wall having a hollow structure, and the inside of the hollow is made to be a vacuum, it is not necessary to perform vacuum sealing in the sealing step, so that the sealing can be easily performed. It has an excellent effect.

Further, since the container has the single seal structure, the container can be miniaturized and the height can be reduced, and the mass productivity can be improved.

According to the invention of claim 4, the sealing process can be facilitated, the container can be made smaller and the height can be reduced, and the thermal efficiency related to the temperature correction of the crystal unit can be improved. It has an excellent effect that it can be converted.

The invention of claim 5 has an excellent effect that the heat insulating effect can be further improved because the inside of the container is evacuated.

The invention of claim 6 has an excellent effect that the heat insulating effect can be further improved because both the base and the cover constituting the container have a hollow structure and the inside of the hollow has a vacuum structure.

The invention of claim 7 has an excellent effect that the power consumption can be reduced because the thermal efficiency related to the temperature correction of the crystal unit is improved.

According to the invention of claim 8, in the invention of claim 6 or 7, the excellent effect of further improving the heat insulating effect and the double structure of the vacuum structure make one vacuum atmosphere deteriorated or broken. Even in such a case, it is possible to maintain an excellent vacuum atmosphere in the container of the highly stable piezoelectric oscillator.

[Brief description of drawings]

FIG. 1 is a sectional view for explaining a first preferred embodiment of a highly stable piezoelectric oscillator according to the present invention.

FIG. 2 is a sectional view for explaining a second preferred embodiment of a high stability piezoelectric oscillator according to the present invention.

FIG. 3 is a cross-sectional view for explaining a third preferred embodiment of a highly stable piezoelectric oscillator according to the present invention.

FIG. 4 is a sectional view for explaining a fourth preferred embodiment of a high stability piezoelectric oscillator according to the present invention.

FIG. 5 is a sectional view for explaining a fifth preferred embodiment of a highly stable piezoelectric oscillator according to the present invention.

FIG. 6 is a cross-sectional view for explaining a conventional highly stable piezoelectric oscillator.

[Explanation of symbols]

1 Temperature chamber type piezoelectric oscillator 2 constant temperature bath 3 Temperature-sensitive element (sensor) 4 Heating element (heater) 5 Inner container 6 outer container 7 printed circuit board 8 Piezoelectric vibrator 9 sensors 10 heater 11 base 12 lead terminals 13 Inside the container 14 cover 15 Highly stable piezoelectric oscillator 16 Highly stable piezoelectric oscillator 17 Resin 18 High stability piezoelectric oscillator 19 cover 20 Inside the container 21 Highly stable piezoelectric oscillator 22 Highly stable piezoelectric oscillator 23 base 24 Inside the container

Claims (8)

[Claims] 1. A high-stability piezoelectric oscillator in which a container contains a printed circuit board on which a piezoelectric vibrator, an oscillating circuit, a temperature sensitive element, and a heating element are housed is a vacuum. . 2. The highly stable piezoelectric oscillator according to claim 1, wherein the printed circuit board is coated with resin so as to cover at least the piezoelectric vibrator, the temperature sensitive element, and the heating element. 3. A piezoelectric oscillator in which a printed board on which a piezoelectric vibrator, an oscillation circuit, a temperature sensitive element, and a heating element are mounted is housed in a container, wherein the container has a wall with a hollow structure,
A highly stable piezoelectric oscillator characterized in that the inside of the hollow is a vacuum. 4. The highly stable piezoelectric oscillator according to claim 3, wherein the printed circuit board is coated with resin so as to cover at least the piezoelectric vibrator, the temperature sensitive element, and the heating element. 5. The highly stable piezoelectric oscillator according to claim 3, wherein the inside of the container is vacuum. 6. A piezoelectric oscillator in which a printed board on which a piezoelectric vibrator, an oscillation circuit, a temperature sensitive element, and a heating element are mounted is housed in a container consisting of a base and a cover, wherein the base and the cover have a hollow structure and are hollow. A highly stable piezoelectric oscillator characterized by having a vacuum inside. 7. The high-stability piezoelectric oscillator according to claim 6, wherein the printed circuit board is coated with resin so as to cover at least the piezoelectric vibrator, the temperature sensitive element, and the heating element. 8. The highly stable piezoelectric oscillator according to claim 6, wherein the inside of the container is vacuum.