Abstract: A series piezoelectric resonator is connected in series between an input terminal and an output terminal. A first electrode of a first parallel piezoelectric resonator is connected to a connection point between the input terminal and the series piezoelectric resonator, and a second electrode of the first parallel piezoelectric resonator is connected to a first terminal of a first inductor. A first electrode of a second parallel piezoelectric resonator is connected to a connection point between the series piezoelectric resonator and the output terminal, and a second electrode of the second parallel piezoelectric resonator is connected to a first terminal of a second inductor. Second terminals of the first and second inductors are grounded. An additional piezoelectric resonator is connected between the second electrode of the first parallel piezoelectric resonator and the second electrode of the second parallel piezoelectric resonator.

Abstract: A thin film bulk acoustic resonator (507b) comprises a substrate (101b), an acoustic mirror layer (508b) provided on the substrate (101b), including a plurality of impedance layers (502b, 503b) alternatively having a high acoustic impedance and a low acoustic impedance, and a piezoelectric thin film vibrator (509b) provided on the acoustic mirror layer (508b), including a lower electrode (504b), a piezoelectric thin film (105b) and an upper electrode (506b). The sum of a thickness of the lower electrode (504b) and a thickness of the upper electrode (506b) is 5% or more and 60% or less of a whole thickness of the piezoelectric thin film vibrator (509b), and the thickness of the lower electrode (504b) is larger than the thickness of the upper electrode (506b).

Abstract: A piezoeletric resonator includes: a substrate; a lower electrode formed on or above the substrate; a piezoeletric body formed on or above the lower electrode; an upper electrode formed on or above the piezoeletric body; and a cavity under a vibrating portion formed by the lower electrode, the piezoeletric body, and the upper electrode. Where a resonant frequency of vibration with a thickness of the vibrating portion being a half of a wavelength is taken as fr, an average of ultrasonic velocity in a material forming the cavity is taken as Vc, and a value determined based on the resonant frequency fr and the average of ultrasonic velocity Vc is taken as ?c (=Vc/fr), a depth of the cavity is set so as to be equal to or larger than n×?c/2??c/8 and equal to or smaller than n×?c/2+?c/8.

Abstract: The present invention is directed to a piezoelectric resonator filter for allowing a high-frequency signal in a desired frequency band to pass therethrough, including: two or more reactance elements in serial connection between input and output terminals; at least three or more piezoelectric resonators in parallel connection between the input and output terminals; and an inductor having a grounded end. Among the three or more piezoelectric resonators, only those piezoelectric resonators which do not adjoin each other in the equivalent circuit are connected in common to the inductor.

Abstract: A driving circuit for a piezoelectric transformer is provided, which ensures lighting of all the cold-cathode tubes connected to the piezoelectric transformer, and reduces the difference in brightness between the cathode tubes during steady lighting, thereby enhancing reliability and performance. A plurality of cold-cathode tubes connected to a secondary side of the piezoelectric transformer, and a cold-cathode tube output detector circuit connected in series to a plurality of cold-cathode tubes, for detecting an output state of the respective cold-cathode tubes are provided, and the driving of the piezoelectric transformer is controlled based on a detection signal from the cold-cathode tube output detector circuit. Because of this, the piezoelectric transformer performs the same operation as that with respect to one cold-cathode tube.

Abstract: A driving circuit for a piezoelectric transformer is provided, which is capable of driving a piezoelectric transformer at a high efficiency and with low distortion, and being miniaturized. At the commencement of lighting a cold-cathode fluorescent tube, a digital controller fixes frequencies of first and second control signals VC1 and VC2 at a predetermined frequency and controls the phase difference therebetween so that an output power of the piezoelectric transformer becomes from substantially zero to a predetermined output power. After lighting of the cold-cathode fluorescent tube, the digital controller controls the phase difference between the first and second control signals VC1 and VC2 so that current detecting data CD substantially is matched with reference data RD.

Abstract: A low loss, small scale piezoelectric transformer, suited for a cold cathode tube load, and having a high effective coupling factor, is provided using a piezoelectric plate having a single polarization direction. Controlling the dimensions of the third electrode portion 15a constituting the high impedance portion makes it possible easily to adjust the capacitance of the electrostatic capacitor formed between the first electrode portion 12 and the third electrode portion in accordance with the load. Also, the second electrode portion 13 and the fourth electrode portion 15b constituting the low impedance portion are substantially equal in area and the third electrode portion and the fourth electrode portion are formed in one piece, so that energy propagation efficiency can be increased.

Abstract: A filter module includes a substrate and a plurality of resonators formed on the substrate and utilizing longitudinal vibration along the thickness of a piezoelectric layer. A plurality of external connection terminals are formed above or below the piezoelectric layer so as to be electrically connected to external circuits and also electrically connected to some of the plurality of resonators through a plurality of interconnects formed to the side of the piezoelectric layer to which the external connection terminals are formed.

Abstract: The present invention provides a light emission control device that can drive a plurality of cold cathode fluorescent tubes independently only by connecting a plurality of piezoelectric transformers to only one piezoelectric inverter circuit. A first phase control portion that outputs a signal for changing a phase of the third and the fourth driving control signals with respect to a phase of the first and the second driving control signals to the second driving portion, and a second phase control portion that outputs a signal for changing a phase of the fifth and the sixth driving control signals with respect to a phase of the first and the second driving control signals to the third driving portion are provided in the piezoelectric inverter circuit. Thus, the phase difference of the driving control signals is controlled, so that the output powers to the plurality of cold cathode fluorescent tubes are controlled.

Abstract: A low loss, small scale piezoelectric transformer, suited for a cold cathode tube load, and having a high effective coupling factor, is provided using a piezoelectric plate having a single polarization direction. Controlling the dimensions of the third electrode portion 15a constituting the high impedance portion makes it possible easily to adjust the capacitance of the electrostatic capacitor formed between the first electrode portion 12 and the third electrode portion in accordance with the load. Also, the second electrode portion 13 and the fourth electrode portion 15b constituting the low impedance portion are substantially equal in area and the third electrode portion and the fourth electrode portion are formed in one piece, so that energy propagation efficiency can be increased.

Abstract: A compact and high-power piezoelectric transformer is realized by using higher order longitudinal extensional mode vibrations and increasing an effective electromechanical coupling factor by a primary electrode which consists of plural electrodes.

Abstract: A driving circuit for a piezoelectric transformer is provided, which ensures lighting of all the cold-cathode tubes connected to the piezoelectric transformer, and reduces the difference in brightness between the cathode tubes during steady lighting, thereby enhancing reliability and performance. A plurality of cold-cathode tubes connected to a secondary side of the piezoelectric transformer, and a cold-cathode tube output detector circuit connected in series to a plurality of cold-cathode tubes, for detecting an output state of the respective cold-cathode tubes are provided, and the driving of the piezoelectric transformer is controlled based on a detection signal from the cold-cathode tube output detector circuit. Because of this, the piezoelectric transformer performs the same operation as that with respect to one cold-cathode tube.

Abstract: The area of an opening C of a cavity 31 is equal to or greater than the area of a horizontal cross section D of a vibrating section 10. The vibrating section 10 is placed on a support section 20 at a position such that a vertical projection of the vibrating section 10 onto a substrate 30 is accommodated within the opening C of the cavity 31. Moreover, the sum of a vertical thickness t1 of the vibrating section 10 and a vertical thickness t2 of the support section 20 is equal to one wavelength of a resonance frequency fr of an acoustic resonator 1 (one wavelength=t1+t2), while the thickness t1 of the vibrating section 10 and the thickness t2 of the support section 20 are different from each other (t1?t2). Thus, neither the thickness t1 of the vibrating section 10 nor the thickness t2 of the support section 20 is equal to the half wavelength of the resonance frequency fr.

Abstract: There is provided a method for driving a piezoelectric transformer in which a driving efficiency and the reliability in terms of withstand power and distortion can be enhanced by suppressing a higher order vibration mode exited by a harmonic component other than a driving frequency included in a driving signal of the piezoelectric transformer without using an inductive element. The driving signal applied to a primary side electrode of the piezoelectric transformer is a signal in a rectangular waveform having a time period ?T in which a level is a maximum potential (2V) or a minimum potential (0), obtained by multiplying a period T of the driving signal by a predetermined time ratio ?. The time ratio ? is set to be smaller than 0.5 and so as to minimize a sum of ratios of amplitudes of respective higher order vibration modes with respect to an amplitude of a vibration mode exciting the piezoelectric transformer.

Abstract: An acoustic resonator device includes a substrate, a first acoustic resonator and a second acoustic resonator. The first acoustic resonator is formed on the substrate, and has a first upper electrode, a first piezoelectric layer, and a first lower electrode layer, and resonates in a ?/4 mode at a first resonant frequency. The second acoustic resonator is formed on the substrate, and has a second upper electrode layer, a second piezoelectric layer, and a second lower electrode layer, and resonates in a ?/2 mode at a second resonant frequency different from the first frequency. In the acoustic resonator device, materials and thicknesses of the first lower electrode layer and the second lower electrode layer are common and substantially equal, and materials and thicknesses of the first piezoelectric layer and the second piezoelectric layer are common and substantially equal.

Abstract: A piezoelectric element of the present invention includes a substrate, a lower electrode layer, a piezoelectric layer, an upper electrode layer, a cavity portion formed below a piezoelectric vibrating portion, and at least two bridging portions. The at least two bridging portions are formed so as not to be line-symmetric with respect to any line segment traversing the piezoelectric vibrating portion and/or so as not to be point-symmetric with respect to any point in the piezoelectric vibrating portion in a projection of the piezoelectric vibrating portion in the laminating direction.

Abstract: A series piezoelectric resonator 11 is connected in series between an input terminal 15a and an output terminal 15b. A first electrode of a parallel piezoelectric resonator 12a is connected to a connection point between the input terminal 15a and the series piezoelectric resonator 11, and a second electrode of the parallel piezoelectric resonator 12a is connected to a first terminal of an inductor 13a. A first electrode of a parallel piezoelectric resonator 12b is connected to a connection point between the series piezoelectric resonator 11 and the output terminal 15b, and a second electrode of the parallel piezoelectric resonator 12b is connected to a first terminal of an inductor 13b. Second terminals of the inductors 13a, 13b are grounded. An additional piezoelectric resonator 14 is connected between the second electrode of the parallel piezoelectric resonator 12a and the second electrode of the parallel piezoelectric resonator 12b.

Abstract: The present invention relates to a piezoelectric resonator including: a substrate; a lower electrode provided on or above the substrate; a piezoelectric member 101 provided on or above the lower electrode; an upper electrode 102 provided on or above the piezoelectric member; and a cavity 104 provided below a vibration member consisting of the lower electrode, the piezoelectric member, and the upper electrode. In the case where a resonance frequency of vibration with a thickness of the vibration member being a half of a wavelength is taken as fr1, an average of ultrasonic velocity in a material forming the cavity is taken as Vc2, and a value determined based on the resonance frequency fr1 and the average of ultrasonic velocity Vc2 is ?c (=Vc2/fr1), a depth t2 of the cavity is set as shown below, ( 2 ? n - 1 ) × ? ? ? ? c 4 - ?c 8 ? t2 ? ( 2 ? n - 1 ) × ? ? ? ? c 4 + ? ? ? ? c 8 , where n is an arbitrary natural number.

Abstract: A piezoelectric device 100 includes first and second piezoeletric resonators 110, 120. The first piezoeletric resonator 110 has a structure in which a cavity 111, a lower electrode 112, a piezoeletric layer 113, and an upper electrode 114 are formed on a substrate 101. The second piezoeletric resonator 120 has a structure in which a cavity 121, a lower electrode 122, a piezoeletric layer 123, and an upper electrode 124 are formed on the substrate 110. A feature of the above-structure piezoelectric device 100 is that the piezoeletric layers 113, 123 have the same film thickness and the depth t1 of the cavity 111 of the first piezoeletric resonator 110 is different from the depth t2 of the cavity 121 of the second piezoeletric resonator 120.

Abstract: A piezoeletric resonator includes: a substrate; a lower electrode formed on or above the substrate; a piezoeletric body formed on or above the lower electrode; an upper electrode formed on or above the piezoeletric body; and a cavity under a vibrating portion formed by the lower electrode, the piezoeletric body, and the upper electrode. Where a resonant frequency of vibration with a thickness of the vibrating portion being a half of a wavelength is taken as fr, an average of ultrasonic velocity in a material forming the cavity is taken as Vc, and a value determined based on the resonant frequency fr and the average of ultrasonic velocity Vc is taken as ?c (=Vc/fr), a depth of the cavity is set so as to be equal to or larger than n×?c/2??c/8 and equal to or smaller than n×?c/2+?c/8.