JPH06338751A - Crystal resonator - Google Patents

Abstract

PURPOSE:To obtain a crystal resonator adapted to an oscillator by adjusting the atmosphere in the air-tight vessel of the crystal resonator in onder to reduce the overshoot of the oscillation frequency at the time of the rise of an oscillator to shorten the rise time. CONSTITUTION:Gaseous argon is used as gas in the air-tight vessel of the crystal resonator and its pressure is set to 50000+ or -10000Pa or gaseous nitrogen or dry air is used as this gas and its pressure is set to 35000+ or -75000Pa to control the transmission speed of heat from the vessel to the crystal resonator piece, thereby reducing the overshoot of the oscillation frequency at the time of the rise of the oscillator to shorten the rise time.

Description

Detailed Description of the Invention

[0001]

[Industrial application] The present invention relates to an atmosphere inside a container of a crystal unit.

[0002]

2. Description of the Related Art Conventionally, the atmosphere inside the container of a crystal oscillator has generally been atmospheric pressure or pressure of dry air, nitrogen gas, argon gas, or vacuum.

[0003]

In a thick crystal oscillator used in a highly stable crystal oscillator using a constant temperature oven, the oscillation frequency overshoots when the power of the constant temperature oven is increased in order to shorten the initial rise time. Therefore, there is a problem that it is difficult to shorten the rise time.

[0004]

As means for solving the problems, as a gas in the airtight container of the crystal unit, argon gas is used, and the pressure is selected to be 50,000 ± 10000 Pa, or nitrogen gas or dry air is used. By adjusting the heat transfer rate from the container to the crystal vibrating piece by selecting the pressure to be 35000 ± 7500 Pa, the overshoot of the oscillation frequency at the time of the rise of the oscillator is reduced and the rise time is shortened. Settled.

[0005]

[Example] The thermal conductivity of gas is air = 2.6 × 10 ⁻⁴ W
/ Cm · deg, nitrogen gas = 2.61 × 10 ⁻⁴ W / cm
・ Deg, argon gas = 1.77 × 10 ^-4 W / cm ・
It is deg. The thermal conductivities of air and nitrogen gas are almost equal, but that of argon gas is obviously low.

The element that determines the oscillation frequency is the crystal piece in the crystal unit. In an oscillator using a constant temperature oven, the factor that determines the rising characteristics depends on how quickly the crystal piece reaches a temperature that is set to everywhere. The heat transfer path to the crystal piece includes conductive heat transmitted from the container wall surface through the atmosphere in the container, radiant heat radiated from the container wall surface, and conductive heat transferred from the support part of the crystal piece.

The heat from the supporting portion and the radiant heat from the wall surface of the container are uniquely determined by the crystal oscillator. The radiant heat of this heat is small, and most of it is heat from the supporting portion. The heat supplied from the support part is supplied to the crystal piece from the connection part with the support part. This results in local heating of the crystal piece from the connection with the support. From the viewpoint of thermal conductivity, the thermal conductivity is quartz = 0.14 W / cm · de.
g, brass = 1.4 W / cm · deg, which is an order of magnitude worse than the metal used for the support. Poor heat conduction of the crystal not only causes a delay in heat transfer but also causes distortion in the crystal piece and causes frequency fluctuations. Therefore, it is necessary to prevent distortion as much as possible. For this purpose, it is necessary to uniformly heat the entire crystal piece.

In order to uniformly heat the entire crystal piece, it is essential to use conduction heat in an atmosphere having the highest degree of heat transfer to the crystal piece. The amount of conduction heat through the atmosphere in the airtight container needs to be sufficient to offset the trouble caused by the heat transferred from the support portion to the crystal piece.
Considering the gas, air, nitrogen gas, and argon gas in the airtight container of the crystal unit, the pressure is set to 1 as shown in FIG.
When the pressure is set to 01080 Pa, the frequency rises quickly, but since it overshoots once and then falls, it takes time to stabilize. The cause of this is that heat is largely transferred to the crystal piece by the atmosphere in the airtight container, and the countermeasure may be to reduce the thermal conductivity of the atmosphere in the airtight container.
The method was solved by lowering the pressure of the gas and adjusting the thermal conductivity so as not to cause overshoot and to supply heat to the entire crystal piece in balance with the heat from the support.

For argon gas, 50000 ± 1
Just balance at 0000Pa. The thermal conductivity of dry air or nitrogen gas is higher than that of argon gas, so the pressure is much lower and 35000 ± 7500P.
Just balance with a. In addition to the characteristics, the gas was selected considering that it is usually available and that the price is relatively low. Krypton gas is the best choice because of its characteristics. The thermal conductivity of krypton gas is 0.94 × 1
Since it is 0 ⁻⁴ W / cm · deg, the pressure is 94150 ±
Just balance at 15000Pa. Regarding pressure, neither depressurization nor pressurization is required, and the pressure can be used at 101080 Pa.

[0010]

EFFECTS OF THE INVENTION By adjusting the atmosphere of the airtight container of the crystal oscillator, the rising characteristic of the oscillation frequency can be remarkably improved in the oscillator using the constant temperature oven. Not only was the productivity of the oscillator used greatly improved and the cost was reduced, but the oscillator characteristics were improved and stabilized, so reliability was improved and inexpensive products could be provided.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between an overshoot of a rising frequency of an oscillator depending on a type of gas and a pressure in an airtight container.

Claims (3)

[Claims] 1. A crystal unit comprising a quartz oscillating piece housed in a hermetically sealed container, wherein an atmosphere inside the airtight container is changed to adjust a heat transfer rate from the container to the crystal oscillating piece. And a crystal unit. 2. The atmosphere inside the container is set to a pressure of 50,000 ± 1.
The quartz oscillator according to claim 1, wherein the argon gas is 0000 Pa. 3. The atmosphere inside the container is set to a pressure of 35000 ± 7.
The crystal oscillator according to claim 1, wherein nitrogen gas or dry air of 500 Pa is used.