JPH0629776A - Multimode quartz vibrator - Google Patents

Abstract

PURPOSE:To raise a guaranteed extent of attenuation by setting the electrode gap to the peak value of the guaranteed extent of attenuation or its vicinity. CONSTITUTION:An input/output electrode is formed on one face of a quartz piece, and a common electrode is formed on the other face, and one face where the input/output electrode is formed is approximated to a shield electrode to raise the guaranteed extent of attenuation. A gap G between the face where the input/output electrode is formed and the shield electrode is set to the peak value of the guaranteed extent of attenuation or its vicinity, namely, 15 to 40mum. That is, the guaranteed extent of attenuation is raised in accordance with reduction of the electrode gap G in any case when a center frequency fo of a multimode vibrator is set to 22MBz, 45MHz, and 90MBz, but the peak value is held in the vicinity of 25mum in the range of 15 to 40mum, and the guaranteed extent of attenuation is quickly reduced when it is lower than 25mum. Consequently, the electrode gap G by which the high guaranteed extent of attenuation is obtained is obtained in accordance with relations between the electrode gap G and the guaranteed extent of attenuation.

Description

Detailed Description of the Invention

[0001]

The present invention relates to an MCF (Monolithic Cry).
The present invention relates to a multimode crystal oscillator (as a stal filter), which is a field of application, and particularly relates to a multimode oscillator that enhances a guaranteed attenuation amount.

[0002]

BACKGROUND OF THE INVENTION A multimode oscillator is used in communication equipment or the like as a device for obtaining a predetermined filter characteristic (transmission characteristic) by utilizing acoustic coupling between, for example, two pairs of electrodes formed on a quartz piece. . One of these is to increase the guaranteed attenuation by reducing the leakage signal due to the electrical coupling between the input and output electrodes (see Japanese Patent Application No. 60-118993 and Japanese Patent Application No. 63-27).
3981, Japanese Patent Application No. 1-83007).

[0003]

2. Description of the Related Art FIGS. 6 to 8 are views for explaining a conventional example of such a multi-mode oscillator. FIG. 6 (a) is a sectional view and FIG. 7 (ab) is a quartz piece. The figure which shows the front and back, 8th
The figure is a bottom view of the container body. The multimode oscillator is formed by enclosing the crystal piece 1 in a closed container 2. The crystal piece 1 is composed of, for example, an AT-cut thickness sliding oscillator. The divided input / output electrodes 3 and 4 are formed on one main surface 1a, and the common electrode 5 is formed on the other main surface 1b. Input / output electrode 3,
Extraction electrodes 6, 7, and 8 extend from the common electrode 5 and the common electrode 5, respectively. The closed container 2 is composed of a concave container body 9 and a metal lid 10 formed by seam welding. Bottom 9a of container body 9
In this case, the shield electrode 11 is centralized and the input / output connection electrodes 12 and 13 are metalized on both sides. Shield electrode 1
Reference numeral 1 is connected to the common electrode lead electrode 8 by wire bonding or the like (not shown), and the input / output connection electrodes 12 and 13 are connected to the input / output lead electrodes 6 and 7 by a conductive adhesive agent 14 or the like. The shield electrode 11 and the input / output electrodes 3 and 4 are opposed to each other by the thickness of the conductive adhesive 14 so that a gap (electrode gap G) is formed between one main surface of the crystal blank 1 and the bottom surface of the container body 9. And)). The shield electrode 11 and the input / output connection electrodes 12 and 13 are exposed on the outer surface of the container body 9 and serve as terminals for surface mounting. In such a structure, the leak signal that propagates directly due to the electrical coupling between the input / output electrodes 3 and 4 is shielded by the shield electrode 11, so that the reduction of the guaranteed attenuation amount is prevented. In particular, the electrode gap G corresponds to the thickness of the conductive adhesive 14 and is significantly reduced. Therefore, it is possible to enhance the shielding effect and expect a large increase in the guaranteed attenuation amount. The guaranteed attenuation amount here indicates the attenuation amount A (dB) at a point where the center frequency f _{0 is} lowered by 910 KHz, as shown in FIG. 9.

[0004]

However, in the above-mentioned structure, when the thickness of the conductive adhesive 14 is reduced to reduce the electrode gap G, there is a problem that the guaranteed attenuation amount decreases contrary to the expectation.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to further clarify the relationship between the electrode gap and the guaranteed attenuation amount, and to provide a multimode oscillator which enhances the guaranteed attenuation amount.

[0006]

SOLUTION: The solution is to find that the electrode gap has an optimum value (singular point), and set the electrode gap to the peak value of the guaranteed attenuation amount and its vicinity. Furthermore,
Specifically, the solution is to set the electrode gap to 15 μm to 40 μm. Hereinafter, one embodiment of the present invention,
This will be described with an experimental example that clarifies these.

[0007]

EXAMPLE FIG. 1 (abc) shows the electrode gap (horizontal axis, μ
It is a figure explaining the relationship between a guaranteed attenuation amount (vertical axis, dB) and m). Note that FIG. 1 (a) shows the center frequency f ₀ of the multimode oscillator at about 22 MHz, and FIG. 1 (b) shows 45 MHz.
FIG. 6C shows the case of 90 MHz. Further, in these experimental examples, the bottom wall 9 of the container body 9 in the previous conventional example is used.
The crystal piece 1 was fixed on the holding plate corresponding to a, and the electrode gap G corresponding to the thickness of the conductive adhesive 14 was measured with a microscope (photograph). From these experimental results, in any case, the guaranteed attenuation increases as the electrode gap G becomes smaller, but reaches a peak value in the vicinity of 25 μm out of 15 to 40 μm, and sharply decreases below this value. Especially 22MH
In the case of z "Fig. 1 (a)", the peak value is 80 dB or more, and below is about 8 MHz at 45 MHz "Fig. 1 (b)".
It is understood that it becomes 70 dB in 0 dB and 90 MHz "FIG. 1 (c)". It should be noted that the higher the center frequency, the smaller the electrode gap G for obtaining the peak value. When the present inventor considered the phenomenon with respect to the result of this experiment, it was presumed that it was caused by the following. That is, as shown in FIG. 3, the electrode gap G reaches a peak value, for example, 2
When approaching apart by more than 5 μm, input / output electrodes 3, 4
The leakage signal P ₁ due to the electrical coupling (stray capacitance C ₁ ) between
It flows into (is attracted to) the shield electrode 11 and flows out to the reference potential. Therefore, the input / output electrodes 3 and 4 are shielded and the guaranteed attenuation amount increases. Next, when approaching within 25 μm,
Stray capacitances C ₂ and C ₃ are generated between the input / output electrodes 3 and 4 and the shield electrode 11. Then, the leak signal P ₂ leaks from the input electrode 3 to the output electrode 4 via the stray capacitances C ₂ and C ₃ (FIG. 4). Therefore, it was estimated that the guaranteed attenuation would drop sharply. Also in FIG. 3, the stray capacitance C ₂ , between the shield electrode 11 and the input / output electrodes 3 and 4,
Although it is considered that C ₃ is generated, the leakage signal P ₂ is so small that the leakage signal P ₁ between the input / output electrodes 3 and 4 is further shielded. Further, although the leak signal P ₁ between the input / output electrodes 3 and 4 is a particular problem, the same applies to the leak signal (not shown) generated between the input / output electrodes 3 and 4 and the common electrode 5. Conceivable. Therefore, from the above, by setting the electrode gap G to the peak value of the guaranteed attenuation amount or in the vicinity thereof, for example, between 15 and 40 μm, a multimode oscillator having a good guaranteed attenuation amount is obtained. be able to.

[0008]

[Other Matters] In the above-described embodiment (experimental example), the holding plate (bottom wall of the container body) 9a is provided with the conductive adhesive 1 on both ends of the crystal blank 1.
4 and the electrode gap G between the shield electrode 11 and the input / output electrodes 3 and 4 was used as the thickness.
However, since it is difficult to make the gap G constant (uniform), the gap G may be set as shown in FIG. 5, for example. That is, the thicknesses of the shield electrode 11 provided on the bottom wall of the container body 9 and the output connection electrode 4 are made different by about 20 μ when metallized. Then, one end of the crystal piece 1 is fixed by a conductive adhesive 14 of about 5 μm to obtain an electrode gap G. By doing so, the metallization can be made uniform, so that it is easier to control the electrode gap G to be constant than in the case where only the conductive adhesive 14 is used. Further, since only one end is fixed and the other end is a free end, impact resistance can be improved. In this figure, the input / output electrodes and the extraction electrodes of the crystal blank 1 are omitted. The electrode is led from the other end by wire bonding. As described above, the present invention can be variously modified, and basically, the holding structure of the crystal blank 1 and the like may be designed arbitrarily, that is, the electrode gap between the shield electrode 11 and the input / output electrodes 3 and 4 is basically required. A configuration in which G is close to the peak value of the guaranteed attenuation amount is included in the technical scope of the present invention. Of course, the shield electrode 11 may be a metal plate or the like.

[0009]

The present invention has an optimum value (singular point) for the electrode gap.
Therefore, since the electrode gap is set to the peak value of the guaranteed attenuation amount and its vicinity, it is possible to provide a multi-mode oscillator that enhances the guaranteed attenuation amount, and the practical merit thereof is extremely great.

[Brief description of drawings]

FIG. 1 is a characteristic diagram of a guaranteed attenuation amount with respect to an electrode gap G for explaining the function and effect of the present invention. FIG. 1A shows a center frequency of 22 MHz, FIG. 1B shows 45 MHz, and FIG. 9
This is the case of 0 MHz.

FIG. 2 is a structural cross-sectional view of a multimode oscillator for one example (experimental example) of the present invention.

[Fig. 3] Fig. 3 is a schematic diagram for explaining the function and effect of the present invention, and is a diagram when the electrode gap G is approached with a distance of 25 µm or more.

FIG. 4 is a schematic diagram for explaining the function and effect of the present invention, and is a diagram when the electrode gap G approaches within 25 μm.

FIG. 5 is a cross-sectional view of a multimode oscillator for explaining another embodiment of the present invention.

FIG. 6 is a sectional view of a multimode oscillator for explaining a conventional example.

[FIG. 7] FIG. 7 (a) is a view of one main surface of a quartz piece for explaining a conventional example, and FIG. 7 (b) is a view of the other main surface.

FIG. 8 is a bottom view of a container body for explaining a conventional example.

FIG. 9 is a band characteristic diagram showing a guaranteed attenuation amount of a multimode oscillator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 crystal piece, 2 sealed container, 3 input electrodes, 4 output electrodes, 5 common electrodes, 6, 7 and 8 extraction electrodes, 9 container body, 9a container bottom surface, 10 metal cover, 11 shield electrode, 12 input connection electrodes, 13 output connection electrode, 14 conductive adhesive.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeo Seki 2 days at 1275 Kamihirose, Sayama City, Saitama Prefecture Saitama Office

Claims (2)

[Claims] 1. A guaranteed attenuation amount, wherein an input / output electrode is formed on one main surface of a crystal piece and a common electrode is formed on the other main surface, and one main surface of the crystal piece is brought close to a shield electrode. In the multimode crystal resonator, the multimode crystal resonator is characterized in that the gap between the one principal surface of the crystal piece and the shield electrode is set to the peak value of the guaranteed attenuation amount and its vicinity. . 2. A multimode crystal resonator, wherein a gap for obtaining the peak value of the guaranteed attenuation amount and its vicinity is 15 μm to 40 μm.