JPH07106904A - Crystal vibrator - Google Patents

Abstract

PURPOSE:To provide a crystal vibrator which is applicable to an oscillator by controlling the inside atmosphere of an airtight container of the crystal vibrator in order to shorten the rise time of the oscillator. CONSTITUTION:The helium gas is used in an airtight container of a crystal oscillator and the pressure of this gas is set at 50-5000Pa. Otherwise the nitrogen gas or the dried air is used at 100-10000Pa. By controlling a heat transmission speed to a crystal vibrator piece fromt he container, the starting time of an oscillator can be shortened.

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 is generally 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, if the power of the constant temperature oven is increased in order to shorten the initial rise time, the oscillation frequency overshoots. Therefore, there is a problem that it is difficult to shorten the rise time.

[0004]

As means for solving the problems, the gas inside the airtight container of the crystal unit is helium gas, and the pressure is selected to be 50 to 5000 Pa, or nitrogen gas or dry air is used. The pressure is 1
By adjusting the heat transfer rate from the container to the crystal vibrating piece by selecting from 00 to 10000 Pa, the overshoot of the oscillation frequency at the time of the rise of the oscillator is reduced to shorten the rise time and solve the problem.

[0005]

[Examples] The thermal conductivities of gases are as follows: air = 3.17 × 10 ⁻⁴ W / cm · deg, nitrogen gas = 3.12 × 10 ⁻⁴ W / cm · deg, helium gas = 100 ° C.
It is 17.06 × 10 ⁻⁴ W / cm · deg. The thermal conductivity of air and nitrogen gas are almost equal, but the thermal conductivity of helium gas is obviously high.

The element that determines the oscillation frequency is the crystal piece in the crystal unit. In an oscillator using a thermostatic chamber, 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 conduction heat transmitted from the container wall surface through the atmosphere in the container, radiant heat radiated from the container wall surface, and conduction heat transferred from the support portion 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 the 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 important 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 helium gas in the airtight container of the crystal unit, Fig. 1 shows the rising time of the frequency with respect to the type of the filling gas and the filling pressure, that is, the time from the start of energization to the stabilization of the frequency. Show the relationship. From this graph, with nitrogen gas and dry air, 100 to 1000
0 Pa is suitable, and 50 ~ 50 for Helium gas.
00 Pa is suitable.

As shown in FIG. 2, the relationship between the atmospheric pressure of the filling gas and the CI (crystal impedance) of the crystal unit is shown. According to this graph, the lower the atmospheric pressure of the filling gas is C
It shows that I becomes low. But 10,000P
Even if the pressure of the filling gas becomes lower than that of a, the CI does not decrease much. From this, the pressure of the filling gas of the crystal oscillator is 10,000 Pa or less. From FIG. 1 and FIG. 2 described above, it is appropriate that the type and pressure of the filling gas in the airtight container of the crystal unit be 50 to 5000 Pa in the case of helium gas and 100 to 10000 Pa in the case of nitrogen gas or dry air.

[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 characteristics of the oscillator were stabilized, so reliability was improved and inexpensive products could be provided.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the rise time of an oscillator depending on the type of gas and the pressure in an airtight container.

FIG. 2 is a graph showing a relationship between gas pressure and CI of a crystal resonator.

Claims (3)

[Claims] 1. A crystal unit comprising a crystal swing piece housed in a hermetically sealed container, wherein an atmosphere inside the airtight container is changed in order to adjust a heat transfer rate from the container to the crystal swing plate. And a crystal unit. 2. The atmosphere inside the container is set to a pressure of 50 to 5000.
The crystal resonator according to claim 1, wherein the helium gas is Pa. 3. The pressure inside the container is 100 to 100.
The crystal unit according to claim 1, wherein nitrogen gas or dry air of 00 Pa is used.