JP2738673B2 - Ceramic resonator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a multimode ceramic resonator. <Prior Art> This type of ceramic resonator mainly separates an audio intermediate frequency (hereinafter, referred to as SIF) included in a video signal from a video intermediate frequency (hereinafter, referred to as PIF) in a television receiver. It is used as a ceramic trap element to be removed. FIG. 15 is a diagram showing the structure of a conventional ceramic resonator of this type, and FIG. 16 is an equivalent circuit diagram thereof.
In FIG. 15, 1 is a piezoelectric ceramic substrate, 2 and 3 are a pair of divided electrodes formed on one surface side of the piezoelectric ceramic substrate 1 in the thickness direction, and 4 is divided on the other surface side of the piezoelectric ceramic substrate 1. This is a common electrode formed to face the electrodes 2 and 3. In the above ceramic resonator, when terminals a to d are connected to the divided electrodes 2 and 3 and the common electrode 4 and used as a four-terminal circuit element, a multiplex having a symmetric mode (a) and an oblique symmetric mode (b) is used. Operate in vibration mode. The above ceramic resonator is included in the video signal
When used as a ceramic trap element for removing SIF signals, the resonance frequency f
Set r to 4.5 MHz. FIG. 17 shows a trap characteristic diagram when the ceramic resonator shown in FIG. 15 is used as a ceramic trap element. The horizontal axis represents frequency (MHz), and the vertical axis represents trap amount (dB). . As shown in the characteristic diagram, the trap amount increases rapidly at the frequency of 4.5 MHz, so that the SIF signal is trapped. <Problems to be Solved by the Invention> However, the conventional ceramic resonator shown in FIG. 15 has one resonance frequency fr and one resonance frequency as shown in FIG.
Has only one anti-resonant frequency fa. For this reason, it is effective as a ceramic trap element for removing SIF signals of a television receiver, but cannot be used for applications such as a multi-mode group delay equalizer and has a narrow application range. <Means for Solving the Problems> In order to solve the above-described conventional problems, the ceramic resonator according to the present invention has a pair of divided electrodes and a common electrode arranged on both surfaces of a piezoelectric ceramic substrate so as to face each other. is there.
One of the pair of split electrodes is connected to the common electrode, and a terminal connected to the outside is drawn out only from the common electrode and the other of the pair of split electrodes. Here, the two resonance frequencies of the frequency Frs and the frequency Fra, and the frequency Fas, are set to have two anti-resonance frequencies of Faa, the resonance frequency Frs, Fra and the anti-resonance frequency Fas, Faa are Frs <Fas <Fra <Faa, the resonance frequencies Frs and Fra and the anti-resonance frequency Fa
It has transmission characteristics determined by s and Faa. <Operation> The ceramic resonator according to the present invention is set so as to have two resonance frequencies of the frequency Fra and the frequency Fra, and the frequency Fas has an anti-resonance frequency.
And the anti-resonance frequencies Fas and Faa satisfy Frs <Fas <Fra <Faa, and the resonance frequencies Frs and Fra and the anti-resonance frequencies Fas and F
It has transmission characteristics determined by aa. For this reason, by connecting the terminal drawn out from the common electrode and the other of the pair of split electrodes to an external circuit, it can be used not only as a ceramic trap element for SIF signals etc. but also for applications such as multi-mode group delay equalizers. Can also be used, and the range of applications is significantly expanded. <Embodiment> FIG. 1 is a symbol diagram of a ceramic resonator according to the present invention. In the figure, 1 is a piezoelectric ceramic substrate, 2 and 3 are a pair of divided electrodes formed on one surface side of the piezoelectric ceramic substrate 1 in the thickness direction, and 4 is a pair of divided electrodes on the other surface side of the piezoelectric ceramic substrate 1. This is a common electrode formed to face the electrodes 2 and 3. One of the pair of divided electrodes 2, 3, for example, the divided electrode 3 is directly connected to the common electrode 4 by the conducting wire 5. Reference numeral 6 denotes a terminal connected to the divided electrode 2, and reference numeral 7 denotes a terminal drawn from the common electrode. FIG. 2 is an equivalent circuit diagram of the ceramic resonator shown in FIG. 1, and FIG. 3 is a frequency attenuation characteristic diagram. As shown in FIG. 3, the ceramic resonator shown in FIG.
And two anti-resonance frequencies of frequency Fra and frequency Fas. The resonance frequencies Frs and Fra are expressed by the following equations using the equivalent circuit of FIG. Therefore, by selecting circuit constants such as Ls, Cs, La, Ca, etc.,
A ceramic trap element having two trap frequencies, a multi-mode group delay equalizer, and the like can be realized. FIG. 4 is a plan view showing a specific structure of the ceramic resonator shown in FIG. 1, FIG. 5 is a side view thereof, and FIG. 6 is a bottom view. In this embodiment, a pair of split electrodes 2 and 3 are arranged on one side in the thickness direction of a piezoelectric ceramic substrate 1 formed in a rectangular flat plate shape with a gap g1 therebetween, and on the other side, A common electrode 4 facing the divided electrodes 2 and 3 is provided, and a lead electrode 31 extended from the divided electrode 3 is provided.
And the lead electrode 41 extended from the common electrode 4 are electrically connected by the conducting wire 5. A lead terminal 6 is connected to a lead electrode 21 extended from the split electrode 2,
The lead terminal 7 is connected to the lead electrode 31 of the divided electrode 3 which is connected to the lead electrode 41 of the common electrode 4 by the conducting wire 5. FIG. 7 is a symbol diagram in another embodiment. In this embodiment, the split electrode 3 and the long electrode 4 are connected via a capacitor C. Also in the case of this embodiment, a ceramic resonator having two resonance frequencies fra and Fra can be obtained. FIG. 8 is a plan view showing a specific structure of the ceramic resonator shown in FIG. 7, and FIG. 9 is also a bottom view of the same, showing a lead electrode 31 extended from the divided electrode 3 and a lead electrode 31 extended from the common electrode 4. The capacitor C is formed by the overlapping area of the lead electrode 41 and the overlapped area. Although not shown, a resistor may be inserted in place of the capacitor C. 10 to 12 show another embodiment of the ceramic resonator according to the present invention. First, the symbol diagram of FIG. 10 has a circuit configuration in which two resonators A and B are combined. Resonator A is
A pair of split electrodes 2A and 3A are provided on one side of the piezoelectric ceramic substrate 1A.
And a common electrode 4A facing the divided electrodes 2A and 3A on the other surface.The resonator B also has a pair of divided electrodes 2B and 3B on one surface of the piezoelectric ceramic substrate 1B. In addition to the above, the common electrode 4B facing the divided electrodes 2B and 3B is provided on the other surface side. The split electrodes 3A and 3B of the resonators A and B are connected in common to the common electrodes 4A and 4B by the conducting wire 5. Split electrode 2A of resonator A
Is connected to a lead terminal 6A, and the split electrode 2B of the resonator B is connected to a lead terminal 6B. In order to obtain a ceramic resonator as shown in the symbol diagram of FIG. 10, two ceramic resonators having the configuration as shown in FIG. 1 may be combined, but as shown in FIGS. 11 and 12, The use of the same piezoelectric ceramic substrate 1 to form the ceramic resonators A and B is advantageous in terms of miniaturization, cost reduction, and ease of use of the device. FIG. 11 and FIG.
In FIG. 12, a pair of divided electrodes 2A and 3A and a common electrode 4A constituting a resonator A are provided near one end of the piezoelectric ceramic substrate 1 using a piezoelectric ceramic substrate 1 formed in a rectangular flat plate shape. The structure is such that divided electrodes 2B and 3B and a common electrode 4B that constitute the resonator B are provided at an appropriate distance from the portion. Split electrode 3A of resonator A and split electrode of resonator B
3B is commonly connected by a lead electrode 32, the common electrodes 4A and 4B are commonly connected by a lead electrode 42, and the lead electrode 32 and the lead electrode 42 are electrically connected by, for example, a conductive wire 5 or the like. Then, the split electrode 2 of the resonator A
The lead terminal 6A is connected to the lead electrode 21A extended from the lead electrode 21A, and the lead electrode 21
The lead terminal 6B is connected to B, and the lead terminal 7 is electrically connected to the lead electrode 32. Since the lead electrode 32 is electrically connected to the lead electrodes 42 of the common electrodes 4A and 4B by the conductive wire 5, the lead terminal 7 may be electrically connected to the lead electrode 42. FIG. 13 is a trap characteristic diagram of the ceramic resonator according to the present invention. This characteristic diagram is obtained by the circuit configuration shown in FIG. In FIG. 14, a circuit is formed by combining two ceramic resonators A and B having the structure shown in FIG. As shown in the characteristic diagram of FIG. 13, the resonance frequency F of 10.5 MHz
rs and a resonance frequency Fra of 10.7 MHz, and a ceramic trap element for trapping frequency signals of the two resonance frequencies Frs and Fra is obtained. <Effects of the Invention> As described above, according to the present invention, it is possible to provide a ceramic resonator that can be used not only as a ceramic trap element for SIF signals and the like, but also for applications such as a multi-mode group delay equalizer. it can.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a symbol diagram of a ceramic resonator according to the present invention,
2 is an equivalent circuit diagram of the ceramic resonator shown in FIG. 1, FIG. 3 is a frequency attenuation characteristic diagram, FIG. 4 is a plan view showing a specific structure of the ceramic resonator shown in FIG. Fifth
FIG. 6 is a side view thereof, FIG. 6 is a bottom view, FIG. 7 is a symbol diagram of another embodiment, FIG. 8 is a plan view showing a specific structure of the ceramic resonator shown in FIG. 9 is a bottom view thereof, FIG. 10 is a symbol diagram of another embodiment, FIG. 11 is a plan view showing a specific structure of the ceramic resonator shown in FIG. 10, and FIG. Figure, No.
13 is a trap characteristic diagram of the ceramic resonator according to the present invention, FIG. 14 is a circuit diagram provided for obtaining the trap characteristics shown in FIG. 13, and FIG. 15 is a diagram of a conventional ceramic resonator of this type. FIG. 16 is a diagram showing the structure, FIG. 16 is an equivalent circuit diagram thereof, and FIG. 17 is a trap characteristic diagram when the ceramic resonator shown in FIG. 15 is used as a ceramic trap element. 1, 1A, 1B ... piezoelectric ceramic substrate 2, 3, 2A, 2B, 3A, 3B ... divided electrode 4, 4A, 4B ... common electrode

Claims (1)

(57) [Claims] In a ceramic resonator in which a pair of divided electrodes and a common electrode are disposed on both sides of a piezoelectric ceramic substrate so as to face each other, one of the pair of divided electrodes is connected to the common electrode, and the common electrode and the pair of divided electrodes are connected to each other. It is configured to have two resonance frequencies of frequency Frs and frequency Fra and two anti-resonance frequencies of frequency Fas and Faa, The resonance frequencies Frs, Fra and the anti-resonance frequencies Fas, Faa
Satisfies the following condition: Frs <Fas <Fra <Faa, and has a transmission characteristic determined by the resonance frequencies Frs and Fra and the antiresonance frequencies Fas and Faa. 2. The ceramic resonator according to claim 1, wherein one of the pair of split electrodes and the common electrode are directly connected. 3. The ceramic resonator according to claim 1, wherein one of the pair of split electrodes and the common electrode are connected via a capacitor. 4. The ceramic resonator according to claim 1, wherein one of the pair of split electrodes and the common electrode are connected via a resistor. 5. A plurality of resonators each comprising a pair of said pair of divided electrodes and said common electrode are provided, and said plurality of resonators are formed on the same piezoelectric ceramic substrate. 3. The ceramic resonator according to item 1 or 2. 6. The ceramic resonator according to claim 5, wherein the common electrodes of the plurality of resonators are connected to each other on a piezoelectric substrate.