JPS5854706A - Frequency modulation oscillator - Google Patents

Abstract

PURPOSE:To realize the frequency modulation of microwave band simply, by providing a piezoelectric oscillator oscillated with an electric signal such as audio signal near a resonator. CONSTITUTION:In applying an AC voltage to a piezoelectric element 11a through the input of an electric signal such as audio signal from a terminal 15, the element 11a performs bending oscillation in the thickness direction with electrostrictive effect. Thus, a diaphragm 11b incorporatedly mounted to this element 11a also oscillates. Since the internal volume of a case 1 is changed accompanied with the oscillation of the diaphragm 11b, the resonance frequency of a dielectric resonator 7 is also changed. As a result, FM modulation can be applied. The similar effect can be obtained by using a cavity resonator. The surrounding of the diaphragm plate is desired to be enclosed with a wave absorber to prevent unnecessary resonance and the leakage of electromagnetic waves.

Description

Detailed Description of the Invention The present invention relates to a frequency modulation oscillator (frequency modulator), and in particular, by providing a piezoelectric vibrator around a dielectric resonator and changing the resonant frequency of the dielectric resonator, The present invention relates to an FM oscillator that applies microwave band frequency modulation (hereinafter simply referred to as FM).

Many conventional FM oscillators are of a type in which a resonator is coupled with an 18I variable reactance element (varactor, etc.) to change the resonant frequency. However, in this type of FM oscillator, the variable reactance element is very expensive, so
The problem is that it lacks economic efficiency. Furthermore, as an FM oscillator that includes a mechanical resonance thread, there is a system that uses a sweep motor (sweep motor)4. However, this glazed li'M oscillator has many problems as described below. ing.

The range of use is limited to the low frequency band and no consideration is given to unnecessary oscillations in the microwave band, the electromagnet is large and cannot be used in the microwave band, and there is external noise due to magnetic coupling. Because it is easy to collect, a magnetic shield is required, which increases the cost, and because the drive coil has a movable structure, it is susceptible to changes in position and magnetic circuit over time due to elastic fatigue of the material H. be.

An object of the present invention was to solve the above-mentioned problems, and by using a piezoelectric vibrator, it is possible to reduce the size and cost of the resonator, and to reduce the Q of the resonator.

To provide an FM oscillator capable of applying FM without lowering the frequency.

In order to achieve this object, according to the present invention, in an oscillator using a cavity resonator or a dielectric resonator, a piezoelectric vibrator is mounted on the upper part or the side around the cavity resonator or dielectric resonator. An FM oscillator is provided, characterized in that an FM oscillator is provided, and the FM is applied by vibrating the vibrator with an electric signal such as a sound. Furthermore, there is provided an FM oscillator in which a radio wave absorber is installed around the diaphragm of the piezoelectric vibrator to suppress unnecessary resonance around the diaphragm.

That is, the present invention is constructed using a cavity resonator or a dielectric resonator, and has been achieved by skillfully utilizing the properties of a generally known oscillator.

Next, a schematic cross-sectional view of an oscillator using a dielectric resonator is shown in the first section.
It is shown in the figure and its properties are explained. In the figure, a microstrip line (unbalanced type) 3 is placed on the bottom wall of the oscillator housing 1.
has been installed. The IJ knob line 3 consists of a line conductor 3a, a ground conductor 3b, and a dielectric plate 3c, and the conductors 3a and 3b are separated by the dielectric plate 3c. A dielectric resonator 7 is installed on the dielectric plate 3c with a spacer 5 in between. At the tip of the microstrip line 3, there is an oscillation element (
(as shown) are combined. A frequency adjustment screw 9 made of metal is provided above the resonator 7 and screwed into the earthen wall of the housing 1 . This adjustment screw 9 adjusts the resonant frequency fr of the resonator 7.
used to make adjustments.

That is, by moving the adjustment screw 9 one step lower,
The resonant frequency fr is changed. In other words, this type of oscillator has the property that the internal volume of the casing 1 changes as the adjustment screw 9 moves up and down, and the resonant frequency fr changes, that is, is modulated, by this volume change. Therefore,
If these 6 product changes are applied continuously by means other than the adjustment screw 9, the center frequency will be continuously modulated, assuming that the center frequency is the resonance frequency fr set by the adjustment screw 9. become. The present invention has been devised in view of these properties.

Hereinafter, practical examples of the present invention will be explained in detail with reference to the accompanying drawings.

FIG. 2 is a schematic cross-sectional view of a first embodiment of the present invention in a microwave band MIC (microwave integrated circuit) oscillator. In addition, in Fig. 2 and Figs. 3 to 6 described below,
The same parts as in Figure 1 above are designated by the same reference numerals.

Therefore, in Fig. 2, 1 is the oscillator housing, 3 is the microstrip line (unbalanced type), 3a is the line conductor, and 3b
is a ground conductor, 3C is a dielectric plate, 5 is a spacer, 7 is a dielectric resonator, 9' is a frequency adjustment screw, 11 is a piezoelectric vibrator,
lla is a piezoelectric element, 11b is a diaphragm made from a metal disk,
Reference numeral 13 indicates a 'N1 signal line, 15 indicates an electrical input terminal 11 for audio, etc., and 17 indicates an adhesive material. The components from the housing No. 1 to the resonator No. 7 are arranged in the same way as in FIG. 1 described above. A load (output end) and a negative resistance element (a Gunn diode or an impanto diode (not shown) are connected to the microstrip line 3, and a band reflection type oscillator is configured in the resonator 7.Resonator 7 is often used in microwave band oscillators, etc. these days, and is formed in the form of a vj dielectric cylinder with a high visiting factor.The spacer 5 is a dielectric plate made of a dielectric with a dielectric constant lower than that of the resonator 7. This prevents a decrease in Qo and the occurrence of unnecessary resonance.The adjustment screw q is made of a metal material, and is formed into a cylindrical shape with the upper end open, leaving a peripheral edge portion 9'a at the lower end. The peripheral edge portion 9'a is provided with a projecting edge 9'b that protrudes upward (in the opening direction) from its inner peripheral edge.This metal adjustment screw 9' is Q.

It also has the role of increasing The piezoelectric vibrator 11 includes a piezoelectric element 11a formed in a disk shape of barium titanate porcelain or the like;
It consists of a metal disc diaphragm 11b that is bonded to the bottom surface of the element 11a and also serves as a bottom electrode, and a metal electrode film 11c that is bonded to the top surface. The diaphragm 11b is attached to the flange 9'b via an adhesive lug 17. The adhesive 17 is made of, for example, silicone rubber, and is disposed at four locations on the ridge 9'b to support the diaphragm 11b, taking into consideration the vibration mode of the diaphragm 11b.

Electric signal lines 13 are connected to electrodes on the upper and lower surfaces of the piezoelectric element 11a, respectively. Therefore, when an electrical signal (alternating current) such as audio is input through the input terminal 15 and an alternating voltage is applied to the piezoelectric element 11a, the piezoelectric element 11a will move in the thickness direction (
It performs bending vibration in the vertical direction (in Fig. 1). Therefore, the diaphragm 11b, which is integrally bonded to the piezoelectric element 11a, also vibrates together with the piezoelectric element 1],a. This diaphragm 11
Since the internal volume of the housing 1 changes with the vibration of b, the resonant frequency fr of the resonator 7 is multiplied by FM.

The oscillation frequency of this oscillator is the resonance frequency fr of the resonator 7.
The resonant frequency fr is adjusted by the adjusting screw 9' in the same manner as described in FIG. 1 above when the diaphragm 11b is not vibrating.

As the piezoelectric vibrator 11, it is possible to use a high-performance, small, and inexpensive device (for example, a piezoelectric speaker) that has recently appeared.

Therefore, according to the present invention, a small and inexpensive FM oscillator can be realized.

FIG. 3 is a schematic cross-sectional view of a second embodiment of the invention. In this second embodiment, the adjusting screw 9' and the piezoelectric vibrator 11 in FIG. 2 (first embodiment) are separated, and the vibrator 1l-f is
- is arranged on the side wall of the housing 1, and the principle is the same as that of the first embodiment. In this case, although the modulation sensitivity is slightly weaker than in the first embodiment, there is an advantage that the adjustment of the resonance frequency fr and the modulation sensitivity adjustment can be separated.

FIG. 4 is a schematic sectional view of a third embodiment of the present invention. In this third embodiment, a cylindrical part 1a surrounding the vibrator 11 in FIG. , a radio wave and sound wave absorber] 9 is disposed within the cylindrical portion 1a. This absorber 19 is made of carbon-coated fiber, for example, and absorbs radio waves to prevent unnecessary resonance from occurring due to leakage of electromagnetic fields from the adhesive 17 portion that holds the diaphragm 11b, and also suppresses acoustic effects. It serves to expand.

FIG. 5 is a schematic sectional view of a fourth embodiment of the present invention. In this fourth embodiment, the vertical positions of the piezoelectric element 11a and the diaphragm 11b of the vibrator 11 in the @1-increment implementation of FIG. 2 are reversed, and the piezoelectric element 11a is placed on the resonator 7 side. . Since there is a metal electrode film 11c on the surface of the 8E@element 11a, there is substantially the same effect as in the first embodiment.

FIG. 6 is a schematic cross-sectional view of a fifth embodiment of the present invention. This fifth embodiment is an embodiment for a waveguide type oscillator.

23 is a waveguide cavity resonator, 25 is a Gunn diode, 27
Is Rono'? circuit (low pass filter), 29 is R
F choke is shown. In this case, it is formed into a resonator whose resonant frequency fr is determined by the distance indicated by t.

Therefore, due to the vibration of the diaphragm 11b, t changes by Δt, so that FM is applied. In addition, the diaphragm 11b
Since this serves as a short plate, an RF choke structure is provided to reduce the loss caused by the adhesive [7]. In this case, the difference from the first embodiment shown in FIG. 2 is that it is easily influenced by the acoustic characteristics of the waveguide.

As explained above, since the FIVI oscillator of the present invention does not use a variable capacitance semiconductor element, there is a large high frequency loss due to this, and in cases such as the microwave band, the manufacturing cost is low, and the M lifespan is low. It is effective for a single radio because it can be expected that

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of an oscillator using a dielectric resonator, and FIGS. 2 to 6 show the first to fifth embodiments of the present invention, respectively.
This is a schematic cross-sectional view of an embodiment. 1... Oscillator housing, 7... Dielectric resonator, 9, 9
'...Frequency adjustment screw, 11...Piezoelectric vibrator, l
la... piezoelectric element, llb... diaphragm, 15... electrical signal input terminal for audio, etc., 17 - adhesive system, 19 - radio wave and sound wave absorber, 21... mesh lid, 23... tonami front Cavity resonator, 25-... Gunn diode. % Applicant Fujitsu Limited Patent Attorney Akira Seki Patent Attorney Kazuyuki Nishidate Patent Attorney 1) Yukio Patent Attorney Akira Yamaguchi Figure 3q b 3c Figure 4 3b 3c Figure 6 23 17 19

Claims (1)

[Claims] 1. In an oscillator using a cavity resonator or a dielectric resonator, a piezoelectric vibrator is disposed above or on the side around the cavity resonator or dielectric resonator, and the vibration A frequency modulation oscillator whose characteristic is that frequency modulation is applied by vibrating the device with an electrical signal such as a sound. 2. The frequency modulation oscillator according to claim 1, wherein a radio wave absorber is installed around the diaphragm of the piezoelectric vibrator to suppress unnecessary resonance around the diaphragm.