JPS5932005B2 - crystal oscillator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a crystal oscillator used in, for example, a crystal watch.

Conventionally, many crystal resonators have been sealed in a special container, and the drive circuit has been implemented by mounting independent circuit components such as integrated circuits, capacitors, and trimmers on a circuit board together with the crystal resonator. It was formed by doing.

However, this makes mounting work such as soldering difficult,
What's worse is that because the high-frequency part is exposed to the outside, even if the oscillation frequency of the crystal resonator is adjusted to the desired value, the oscillation frequency will shift due to the influence of stray capacitance around the circuit board. There was a drawback.

Therefore, after mounting on a circuit board, the oscillation frequency had to be finely adjusted with a trimmer, and the trimmer's capacitance variable width had to be widened to widen the frequency adjustment range.

It is an object of the present invention to eliminate the above-mentioned conventional drawbacks, and to make the crystal drive unit smaller, lower in price, and labor-saving in manufacturing.

A feature of the present invention is that a lead frame for connecting a crystal resonator and an integrated circuit element is disposed on the upper surface of a metal substrate, which is one of the components constituting the sealed container, with a dielectric material interposed therebetween. A fixed load capacitance for the crystal resonator drive circuit is generated between the metal substrate and the lead frame, and in addition, a portion extending outward from the cap is formed on at least one side of the metal substrate, and this An elastic electrode plate integrally formed with one of the lead frames is provided toward the protruding part.
A dielectric material is sandwiched between this elastic electrode plate and the above-mentioned extended portion, and the variable load capacitance of the drive circuit for the crystal resonator is generated at that portion.

Embodiments of the present invention will be described below with reference to the drawings.

In FIGS. 1 and 2, 1 is a flat metal substrate which is one of the parts constituting the sealed container, 2 is a first dielectric material disposed in a layer over the entire upper surface of this metal substrate, 3at
3bt...3h are a plurality of lead frames disposed on the upper surface of the dielectric material, and 31 is an elastic electrode plate integrally formed to extend from the lead frame 3h.

In this embodiment, the dielectric material 2 used is a woven or nonwoven fabric made of various synthetic fibers, natural fibers, glass fibers, etc., impregnated with an insulating adhesive such as epoxy, and formed into a sheet.

The lead frames 3a, 3b...3h and the electrode plates 31 are formed from a single metal plate into an appropriate wiring pattern by press punching or etching. Before being bonded to the dielectric material 2, it is connected to the outer peripheral piece 3j as shown in the third figure.

The metal substrate 1, the dielectric material 2, and each lead frame 3a, 3b, .
By heat-suppressing for 70 minutes, the three components are adhesively bonded together.

Thereafter, the outer peripheral piece 3J is cut off from the position indicated by the chain line in FIG.

4 is an integrated circuit element (hereinafter abbreviated as IC chip) die-bonded onto the lead frame 3d.

), and this IC chip and each lead frame 3a, 3
b...3h is wire bonding.

Further, a window hole 2a for exposing the metal substrate 1 near the IC chip 4 is pre-drilled in the dielectric material 2, and the lead frame 3d and the metal substrate 1 are wire bonded through this window hole. has been done.

Further, holding springs 5 and 6 are fixed to the lead frames 3g and 3h, and a crystal resonator 7 is attached to the holding springs in parallel to the metal substrate 1.

8 is a sealing material made of the same material as the dielectric material 2; this sealing material is placed on the same edge of the dielectric material 2, and the flange 9a of the cap 9 and the peripheral edge of the metal substrate 1 are heated and pressed. As a result, the cap 9 and the metal substrate 1 are hermetically sealed.

Note that this sealing work is performed in a vacuum or inert gas atmosphere, and the inside of the cap is replaced with vacuum or inert gas.

Elastic electrode plate 31 integrally formed from lead frame 3h
protrudes outward from the cap 9 and faces the metal substrate 1 as a counter electrode plate, and the elastic electrode plate 31 and the metal substrate 1
A second dielectric material 10 is sandwiched between the two.

As the dielectric material 10, a plastic film sheet such as Mylar or polypropylene is used in this embodiment, but it is not particularly limited.

The elastic electrode plate 31 is bent slightly upward, and a spring force is applied to the elastic electrode plate 31 so that it tends to separate from the metal substrate 1.

The opposing gap between the electrode plate 31 and the metal substrate 1 is defined by the adjustment screw 11 passing through the metal substrate 1, the dielectric material 10, and the elastic electrode plate 31, and the insulating receiving plate 12 into which this adjustment screw is screwed. The adjustment function is achieved by means of an adjustment means.

FIG. 4 shows an example of a drive circuit for the crystal resonator 1.
13 is an inverter, 14 is a resistor, 15 is a buffer, 16
is a divider, 11 is a driver circuit, and each IC
It is formed within the chip 4.

C, , C2 are fixed load capacities, and CT is a variable load capacity.

That is, the lead frame 3h shown in FIGS. 1 and 2,
The capacitance generated between the elastic electrode plate 31 and the metal substrate 1 is the fixed load capacitance C1 and C2 shown in the fourth diagram, and the capacitance generated between the elastic electrode plate 31 and the metal substrate 1 is the fixed load capacitance C1 and C2 shown in the fourth diagram. These are load capacitances C1, C2, and the capacitance generated between the elastic electrode plate 31 and the metal substrate 1 is a variable load capacitance CT shown in FIG.

The fixed load capacity C1t C2 is the lead frame 3h,
By appropriately selecting the facing area between 3g and the metal substrate 1, the facing distance, the material of the dielectric substance 2, etc., the variable load capacity CT can be set to a desired constant value, and the variable load capacity CT can be adjusted by tightening or loosening the adjusting screw 11. By doing so, the bullet is connected to the electrode plate 31
By changing the facing distance between the metal substrate 1 and the metal substrate 1, the capacitance value can be adjusted as appropriate.

Of course, capacitance is generated between the remaining lead frames 3a, 3b, . . . , 3f and the metal substrate 1, but the lead frames 3d and 3e are power terminals, and the lead frame 3b.

3c is an output terminal, lead pieces 3a and 3f are check terminals, and the capacitance between these lead frames and the metal substrate has almost no effect on the vibration of the crystal resonator 7.

In addition, in this embodiment, the oscillation frequency of the crystal oscillator 7 is adjusted by depositing the same material on the drive electrode 7a of the crystal oscillator 1 at a stage before sealing the cap 9 (see FIG. 2). This is done by applying heat by the method described above, or by trimming a part of the drive electrode 7a using an electron beam, a laser beam, or the like.

According to this configuration, the t\luck of the fixed load capacities C1 and C2 is originally small, but even if there is some variation,
Since the frequency can be adjusted by absorbing the l\lack, the oscillation frequency of the crystal resonator γ can be adjusted with extremely high precision.

In addition to minimizing changes in the external conditions that affect the oscillation circuit, the capacitance variable width of the variable load capacitor CT has an oscillation frequency of approximately 4.2 MHz, taking into account the aging of the crystal resonator γ. It suffices if the frequency change amount is about 110PP.

For reference, conventional variable load capacitances require a capacitance variable width that allows a frequency change of 100 PPM or more in the same oscillation frequency band.

FIG. 5 shows an example of a bullet in which the electrode plate 31 is curved in a wavy manner.
By doing so, the bullet has an increased degree of bounce on the electrode plate 31, and the amount of change in capacitance relative to the amount of rotation of the adjustment screw 11 can be reduced, making fine adjustment easier.

Further, depending on the type of the first dielectric material 2, the second dielectric material 10 can be formed integrally with the first dielectric material 2.

As described above, according to the present invention, the fixed load capacitance of the drive circuit of the crystal resonator is generated between the metal substrate, which is one part of the sealed container, and the lead frame. Since the structure generates variable load capacitance of the crystal resonator drive circuit between the integrated elastic electrode plate and the metal substrate, the number of parts of the crystal drive circuit can be reduced, miniaturization, cost reduction, and manufacturing efficiency. It saves labor and is easy to mount on the circuit board.Moreover, since there are few high-frequency parts exposed to the outside, it is less susceptible to external influences such as stray capacitance around the circuit board, and the oscillation frequency is stabilized. It is easy to adjust and can be matched with high precision, and the variable load capacity can be set to a small range of 5 J, making design easy, and the effects are tremendous.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is an enlarged sectional view thereof, FIG. 2 is an exploded perspective view thereof, FIG. 3 is a plan view of the lead piece connected to the outer peripheral piece, and FIG. The figure is a circuit diagram of the crystal driving section, and FIG. 5 is an enlarged perspective view of another embodiment of the elastic electrode substrate. 1... Metal substrate, 3a, 3b to 3h...
・Lead frame, 31...Elastic electrode plate, 4.
... Integrated circuit element, 5, 6 ... Holding spring, 1 ... Bent crystal oscillator, 9 ... Cap, 10
...Dielectric material, 11゜12...Gap adjustment means, C,', C2...Fixed load capacity,
CT...Variable load capacity.

Claims (1)

[Scope of Claims] 1. A sealed container is constituted by a flat metal substrate and a cap, a first dielectric material is formed on the upper surface of the metal substrate, and a plurality of lead frames are formed on the dielectric material. A crystal resonator is connected to a predetermined part of the lead frame via an integrated circuit element and a holding means, and the metal substrate has a portion extending outward from the cap on at least one side thereof. an elastic electrode plate integrally formed with one of the lead frames extends toward the extended portion, and a second dielectric material is provided between the elastic electrode plate and the extended portion. , an adjusting means is provided for adjusting a gap between the elastic electrode plate and the extending portion, and the capacitance generated between the metal substrate and the lead frame is reduced to a fixed load of the drive circuit of the crystal resonator. A crystal oscillator, characterized in that the capacitance generated between the metal substrate and the elastic electrode plate is used as a variable load capacitance of a drive circuit for the crystal resonator. 2. The crystal oscillator according to claim 1, wherein the electrode plate is curved in a wavy manner at a portion facing the extending portion.