JP3102377B2 - Hermetic crystal oscillator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal oscillator,
In particular, the present invention relates to an airtight crystal oscillator that satisfies both functions of airtightness inside an oscillator case while facilitating frequency readjustment.

[0002]

2. Description of the Related Art A crystal oscillator generally comprises a crystal oscillator and an oscillation circuit. The frequency change rate of the oscillation frequency is given by equation (1). ΔF = 1 / [2 · Y (1 + C _L / C ₀ )] (1) where ΔF is the frequency change rate, C _L is the load capacity, C ₁ ,
C ₀ is the series capacitance and the parallel capacitance of the crystal unit, and Y
(= C ₀ / C ₁ ) represents the capacitance ratio of the crystal resonator.
At this time, the load capacitance is a capacitance when the circuit side is viewed from the crystal unit, and is constituted by a capacitor or a stray capacitance of a circuit board. For this reason, when humidity is applied from the outside, the stray capacitance of the circuit board may change due to the humidity. Therefore, there has been proposed an airtight crystal oscillator in which a crystal unit and an oscillation circuit are provided in a case, and the case is completely sealed in order to prevent a change in the stray capacitance of the circuit board.

[0003]

However, in such a hermetic crystal oscillator, even if the oscillation frequency is adjusted at the time of manufacture, slight frequency fluctuations occur due to differences in external conditions when the crystal oscillator is actually mounted. Is inevitable. For this reason, when mounting the crystal oscillator, it is necessary to attach a frequency adjusting component such as a variable resistor as an external component, and readjust the frequency using this component. For this reason, the work of mounting the frequency adjustment component is required, which causes a problem that the mounting operation is complicated, and the mounting area for mounting the frequency adjustment component is also increased, and the size of the device is reduced. The problem of becoming an obstacle has arisen.

The present invention makes it possible to easily re-adjust the frequency of an airtight crystal oscillator, while preventing an increase in the mounting area and the complexity of the mounting operation caused by external components. It is an object to provide a type crystal oscillator.

[0005]

According to the present invention, a quartz oscillator and a frequency adjusting component are provided inside a case, and the case has an opening for adjusting the frequency adjusting component from outside the case. And a closing member for closing the opening, and a lid that covers the opening and the closing member and is soldered to the case. Here, a concave portion is formed in the case, the concave portion has the opening at the bottom surface, and has a tapered step at the peripheral portion thereof, and the lid is a flat surface corresponding to the concave portion. It is preferable that a tapered surface is formed at the peripheral edge of the tapered surface so as to be in contact with the tapered step. Preferably, the opening is formed as a screw hole, and the closing member is configured as a sealing screw screwed into the screw hole. In addition, the lid is
It is preferable to have a concave groove filled with solder along the peripheral edge of the surface, and to have a recess at the center of the surface with which the tip of the solder iron can be engaged.

[0006]

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a partially exploded perspective view showing a schematic configuration of an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of a main part thereof. In these figures, a substrate 10 on which a crystal oscillator (not shown) is mounted is housed in a rectangular parallelepiped case 1. The case 1 has a configuration in which, for example, a rectangular container-shaped cover is placed on a rectangular base, and the joint surface is hermetically sealed. The case 1 is
For example, it is formed by processing a tin-plated iron plate having a thickness of about 2 mm. A circular recess 2 is formed in a part of the upper surface of the case 1, and a screw hole 3 as a circular opening is formed at a substantially central position on the inner bottom surface of the recess 2. The substrate 10 has mounted thereon a frequency adjusting component 11 such as a volume (variable resistor) and a trimmer (variable capacitor) for adjusting the oscillation frequency of the crystal oscillator. Is located just below the screw hole 3.

[0007] A sealing screw 4 can be screwed into the screw hole 3. The annular peripheral edge of the concave portion 2 is formed as a tapered stepped portion 2a having a tapered shape. A disk-shaped lid 5 having a diameter capable of supporting the peripheral portion of the tapered step portion 2a is placed in the concave portion 2, and is integrated with the case 1 by solder 6 at the peripheral portion. Is attached. As shown in plan and side views in FIGS. 3 (a) and 3 (b), the lid 5 has a depth at which the tip of a soldering iron can be engaged at a substantially central position on the upper surface thereof as described later. A depression 5a having a thickness of about 0.5 mm is formed. On the upper surface of the peripheral portion of the lid 5, an annular concave groove 5b is formed along the peripheral edge, and is filled with the solder 6. Further, the lower surface of the concave groove 5b is formed as a tapered surface 5c corresponding to the tapered step 2a of the case 1.

In the hermetically sealed crystal oscillator having this configuration, the case 1 is formed in a sealed structure as described above during manufacture, and then, when adjusting the frequency before shipping, as shown in FIG. Before soldering the lid 5 to the recess 2,
With the sealing screw 4 removed from the screw hole 3,
Then, a jig D such as a driver is inserted into the case, and the frequency adjustment component 11 is operated to adjust the frequency. After this adjustment is made, the sealing screw 4 is screwed into the screw hole 3 to bring the screw hole 3 into a sealed state. Further, the lid 5 is placed on the concave portion 2, and the lid 5 is brazed to the case 1 with the solder 6 at the peripheral edge thereof to be integrated. Thereby, the screw hole 3 in the recess 2 is also sealed by the lid 5, and the airtightness is improved. At this time, the lid 5 and the recess 2 are in a state where the tapered surface 5c and the tapered step 2a are in contact with each other.
Is stably supported in the recess 2.

In order to readjust the frequency after mounting the hermetically sealed crystal oscillator on any device, as shown in FIG. The cover 5 is heated by hitting a depression 5 a provided at the center of the cover 5. Then, when the solder 6 at the peripheral edge portion starts to be melted by this heating, the tip of the soldering iron H is pushed along the surface of the case 1 so that the lid 5 can be removed from the recess 2. At this time, the tapered surface 5c at the peripheral edge of the lid 5 is
Of the solder iron H is generated along the tapered surface 5c, and the tapered surface 5c slides up along the tapered step 2a. The lid 5 can be removed. And
After removing the lid 5, the frequency can be readjusted in the same manner as the frequency adjustment at the time of manufacturing described above.
After the readjustment, the lid 5 is soldered to the case 1 again on the concave portion 2 to ensure the airtightness.

As described above, in this crystal oscillator, the frequency adjusting component 11 is integrally hermetically sealed in the case 1 together with the crystal oscillator and the like. Since the provided screw hole 3 is double-sealed with the sealing screw 4 and the lid 5, high airtightness can be obtained, while the lid 5 and the sealing screw 4 are easily removed, and Since it can be attached, the frequency can be readjusted even after mounting. Therefore, an external component for adjusting the frequency is not required, and the operation for mounting the crystal oscillator can be simplified, and the mounting area can be reduced.

In the above embodiment, since the lid is formed in a circular shape, the removal of the lid by the soldering iron has no directionality, and the work can be facilitated. If so, the lid may have a shape other than circular. If there is no problem in durability or the like, the screw hole may be formed as a mere opening, and a sealing material such as rubber or resin may be inserted or press-fitted into this opening.

[0012]

As described above, according to the present invention, a quartz oscillator and a frequency adjusting component are provided in a case, and an opening for adjusting the frequency adjusting component from the outside of the case is provided in the case. Since a closing member that closes the opening and a lid that covers the opening and the closing member and are soldered to the case are provided, the inside of the case can be hermetically sealed with the closing member and the lid. While the frequency can be adjusted and readjusted. Since the lid is soldered to the case, the frequency can be readjusted by melting the solder and removing the lid, so that the frequency can be readjusted with a simple operation.
In addition, since frequency adjustment components are installed, external components are not required, which makes it possible to avoid complications in mounting work, prevents an increase in the mounting area of the crystal oscillator, and reduces the size of the device in which the crystal oscillator is mounted. realizable.

[Brief description of the drawings]

FIG. 1 is a partially exploded perspective view showing a schematic configuration of an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a part of FIG.

FIG. 3 is a plan view and a front view of a lid.

FIG. 4 is a schematic cross-sectional view for explaining a frequency adjustment operation and a readjustment operation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Case 2 Recess 2a Taper step part 3 Screw hole 4 Sealing screw 5 Lid 5a Depression 5b Recess 5c Tapered surface

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H03B 1/00 H03B 5/00 H03H 9/00 H05K 5/00

Claims (4)

(57) [Claims] 1. A quartz oscillator and a frequency adjusting component are provided in a case, and the case has an opening for adjusting the frequency adjusting component from outside the case, and the opening is closed. A hermetically sealed crystal oscillator, comprising: a closing member that covers the opening and the closing member and soldered to the case. 2. A concave portion is formed in the case, the concave portion has the opening at the bottom surface, and has a tapered step at a peripheral portion thereof, and the lid corresponds to the concave portion. The hermetically sealed crystal oscillator according to claim 1, wherein a flat surface shape is formed, and a tapered surface abutting on the tapered step portion is formed at a peripheral portion thereof. 3. The hermetic crystal oscillator according to claim 2, wherein the opening is formed as a screw hole, and the closing member is a sealing screw screwed into the screw hole. 4. The lid body has a concave groove along which the solder is filled along the peripheral edge of the surface, and has a recess at the center of the surface where the tip of the solder iron can be engaged. 3. An airtight crystal oscillator.