JPH01208004A - Piezoelectric oscillator - Google Patents

Abstract

PURPOSE:To suppress microphonic noise by providing two pairs of electrodes on both main planes of a piezoelectric piece, and connecting the electrode on the main plane on one side of one of those pairs to the electrode on the main plane on the other side of another pair commonly, respectively. CONSTITUTION:The two pairs of electrodes 18(18a,18b) and 19(19a, 19b) confronting with both main planes of a crystal piece 17 are formed adjacently. And draw-out electrodes 20a and 20b to connect the electrodes 18a and 19b commonly are extended to an outer peripheral part on one end side. Also, draw-out electrodes 21a and 21b to connect the electrodes 18b and 19a commonly are extended to the outer peripheral part on the other end side, and are sealed by covering with a metallic cover 11. In such a way, capacitances Ca1, Ca2, Cb1, and Cb2 due to the electrodes 18a, 18b, 19a, and 19b are generated between the cover 11, and it follows that a synthetic capacitance Cx connecting the capacitances Ca1 and Cb2 in parallel is attached on one end side of a quartz oscillator 16 and similarly, on the other end side, a synthetic capacitance Cy is attached between the ground. Therefore, the capacitances Cx and Cy can be set constant even when the crystal piece 17 oscillates, then, the microphonic noise can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Application of the Invention) The present invention is applied to a piezoelectric oscillator using a piezoelectric vibrator as an oscillator, and particularly relates to a crystal oscillator that prevents microphone noise.

(Industrial Application Field) Crystal oscillators are often used as reference sources for frequency and time, etc., as they provide good frequency stability.In recent years, for example, portable ;L of machines etc.
It is frequently used in 1ilJ F Morishita, and there is a desire for something with less so-called microphonic noise caused by vibrations, shocks, etc. (Reference Patent Application No. Sho Fi 219!'10003) (Prior Art) Fig. 4 is a diagram showing a conventional example of a crystal oscillator;
is a schematic circuit diagram, and (b) is a front cross-sectional view of the crystal resonator.

A crystal oscillator uses a crystal oscillator 1 as an oscillator, and for example, a crystal oscillator 1 is connected between the base of an oscillation transistor 2 and a ground potential E.
7. Form an oscillation circuit with bias resistor 3.4.5 and capacitor 6.7. Please note that the power source is ■3. . , the output ■. shall be.

The crystal resonator 1 is, for example, AT-cut and has a disk shape, and has a pair of electrodes 9 facing each other on both main surfaces of a crystal piece 80, and vibrates in a shear-slip vibration state. Then, use the crystal piece 8 as the base 10
and a metal cover 11. A pair of lead wires 13 protrude through the base 1o, and a holder 14 having, for example, a chestnut-shaped tip is erected thereon. Part 1
At this point, attach the extraction electrode 15 of the crystal piece 8 to the tip of the holder 14.
It has a structure in which the outer circumferential portions of both extending ends are held together.

(Problems with the Prior Art) (7) However, in the crystal oscillator with the above configuration, as shown in FIG. ) "Side sectional view of the same figure (n)" where C1 and C2 exist.In other words, electrically, one end is connected to both sides of the crystal resonator 1, and the other end is applied as a ground potential. 5 (h>l. Then, when the crystal piece 8 oscillates due to, for example, vibration or impact, the distance between the training electrode pair 9 and the metal cover 11 is changed to change the values of capacitances C1 and C2, For example, the oscillation frequency is phase-modulated, resulting in so-called micro-on-crystal noise.Especially, in recent years, the housings of electronic devices have become smaller and lighter, and external shocks are more directly transmitted to the crystal oscillator than in the past. For,
There were many terms during which this kind of noise occurred.

(Objective of the Invention) An object of the present invention is to provide a crystal oscillator that suppresses microphonic noise.

(Step 1 of Solution) The present invention provides a multi-electrode type crystal resonator having two pairs of electrodes provided on the living surface of a piezoelectric piece, one set of the electrode pairs on the living surface and the other electrode on the living surface of the piezoelectric piece. The solution is to connect the electrodes on the surface in common, and to connect the electrodes of one set of the electrode pairs and the electrodes on the other surface in common to the oscillator.

(Function of the Invention) The present invention provides a capacitor with a set of electrodes on a single surface between a metal cover that encloses a piezoelectric piece and a metal cover that encloses a piezoelectric piece.
a, and the combined capacitance IL of the capacitance C5□ due to the electrode on the other main surface of the other group, and the electrode field M of the other main surface of the − group, Cbr and the life surface of the other group? 1'Sti by Yong! # produces CV in the synthetic volume with c-2. Therefore, even if the distance between the main surface of the piezoelectric piece and the metal cover changes17 due to rocking, the combined capacitance C8 is the change due to the rocking of the capacitance M, C□ and cbl, and the combined capacitance Cy is the capacitance. Let c b r and the same change in capacitance 0°2 cancel each other out. An embodiment of the present invention will be described below.

(Example) Fig. 1 is a diagram of a crystal oscillator for explaining an example of the present invention.
)) is a side view of a crystal piece. Note that the same parts as in the previous embodiment drawings are given the same numbers and explained.

As with the previous conventional example, the crystal oscillator has a power supply of V, and an as output of V. A crystal resonator 16 serving as an oscillator is connected, for example, between the pace and collector of the oscillation transistor 2, and a bias resistor 3.4.5 and a capacitor 6.7 are provided.
A Colpitts type oscillation circuit is formed (see Figure 4 above).

The crystal resonator 16 has a crystal piece 17 shaped like an AT-cut disk, for example. Two pairs of electrodes 18 and 19 facing each other on the whole surface of the crystal blank 17 are formed by approaching I7.

- Extracting electrodes 20a, 20)) which commonly connect the electrode 18iz on the main surface of one set and the ri electrode 9h on the other main surface of the other set are extended to the outer periphery of one end. In addition, four lead-out poles 21a and 21b, which commonly connect the electrode 18b on the other main surface of the negative group and the electrode 19a on the main surface of the other group, extend to the outer periphery of the other end. Then, the holder 14 erected on the base 10 described above
The outer peripheries of both extended ends of the extraction electrodes 20 and 21 are held between the tips of the electrodes 20 and 21 , and the metal cover 11 is covered and sealed tightly. The vibration state of the crystal resonator 16 is assumed to be thickness shear vibration in the ♀F symmetric mode due to the elastic coupling between the two electrode pairs 18 and 19 [curve (a) i in FIG. 1(b).

Therefore, the crystal oscillator having such a configuration has the following effects.

In the crystal resonator described above, as shown in FIG. 2, electrodes 18n, 18b, 19n, 19b
Niyoru M c -1,c,2,cb,,C,.

``Side sectional view of the same figure (,)'' that produces. That is, electrically, one end side of the crystal resonator 16 has capacitances cal, cb,
A composite capacitor C8 is connected in parallel to set the ground potential to the other end, and a composite capacitor r'ttcy is added to the other end by connecting the capacitors C0 and cbl in parallel to set the ground potential to the ground potential. hll.Therefore, the crystal piece 17 swings due to the external vibration/l!lI7 impact, causing the metal cover 11 and each electrode IF to oscillate.
Even if the excretion changes between in, 18h, 19a, and 19h,
Combined capacitance: 2 with C8 and C7 constant, i.e. various fields)
Even if CAI, CA2, Ch+, CH2 change with distance, container, C11, Chz, and container CA□, Cb
+ cancels out the changes by setting III in the opposite direction of magnitude.

Therefore, in the crystal oscillator with the above configuration, even if the crystal piece 7 oscillates, the combined capacitances Cw and Cy added to both ends of the crystal resonator 16 are kept almost constant, thereby preventing the generation of microphonic noise. It can be prevented.

(Other Matters) In addition, in the second embodiment, the oblique mode of the thickness edge vibration mode was applied, but for example, as shown in FIG. ``Song 1M (b) of the same figure () +)'' may be set to 17 so that no elastic coupling occurs and each is excited in a symmetric mode.

In this case, for example, the 18 side of one electrode is used as the oscillator 17, and the counter electrode 19 side of the other paper is used to simply cancel the vibration by adding mass to change the vibration frequency or suppress the vibration. You can also use it as a convenience. Also, electrode pair 18.1
9 is placed at the end of the crystal piece 17 (by arranging the holder 14, even if the overtone is generated, it will be L. The present invention can be applied to a structure in which the crystal piece 17 substantially oscillates and lies between the electrode and the metal cover, and the present invention can be modified as appropriate without departing from the spirit thereof. In addition, in the present invention, even if electric charges are generated in the electrode pair 18 and 19 due to external electromagnetic wave induction, they will not kill each other, so it can be expected that the influence of EMT (electromagnetic interference) will be reduced. reactor.

(Effects of the Invention) The present invention provides a multi-pole type crystal resonator having two pairs of electrodes provided on both main surfaces of a piezoelectric piece. The electrodes on the other main surface are all connected in common, and the electrodes on the other main surface of the set of electrode pairs and the electrodes on the other main surface + fij are connected in common to form an oscillator, so microphonic noise can be reduced. Please provide a suppressed crystal generator.

[Brief explanation of the drawing]

FIG. 1 is a diagram of a crystal resonator for explaining the crystal oscillator of the present invention, where (11) is a front sectional view and FIG. 1(b) is a side sectional view of a crystal piece. Figure 2 is a diagram explaining the effect of the above embodiment, where (a) is a side view of the crystal resonator, and (b) is a side view of the crystal resonator.
is an electrical equivalent circuit diagram. FIG. 3 is a diagram of a crystal resonator for explaining another embodiment of the present invention, in which FIG. 3(a) is a front view of the crystal piece, and FIG. 3(b) is a side view thereof. Figure 4 is a diagram of a crystal oscillator explaining a conventional example.
) is a schematic circuit diagram, the same figure (bl is a front cross-sectional view of the crystal resonator,
FIG. 5(a) is a side sectional view of the crystal resonator, and FIG. 5(b) is an electrical equivalent circuit diagram. 1.16 ・Crystal resonator, 2 Oscillation transistor, 3
．． 4.5 - Resistor, 6.7 Capacitor, 8.17 Crystal piece, 9.18.19... Electrode pair, 10 Base, 11
Cover, 12 Metal container, 13.Lead wire, 14. Holding, 15.20.21.Extraction electrode. Figure 4 (a) Figure 4 Figure 5 Figure 5 (b) 1

Claims (1)

[Claims] In a piezoelectric oscillator in which an oscillation circuit uses a piezoelectric vibrator sealed in a metal container with electrode pairs facing each other on both main surfaces of a piezoelectric piece as an oscillator, there are two sets of electrode pairs provided on both main surfaces of the piezoelectric piece. , an electrode on one main surface of one set of the electrode pairs and an electrode on the other main surface of the other set are commonly connected, and an electrode on the other main surface of the one set of the electrode pairs and an electrode on the other main surface of the other set are connected in common. A piezoelectric oscillator characterized in that thickness-shear vibration is excited by commonly connecting the oscillators.