It was more than 10 years ago that the first map navigation system, as an example of invehicle information system, has appeared in the market in Japan. Today's navigation system has been improved to the level that the latest system has 10 micro-processors, 7 MBytes of memories, and 4 GBytes of external data storage for map database. From the viewpoint of the automobile driver, there are still some problems with the system. Major problems in general are a lack of traffic information, better human interface, and a need for cost-reduction. The introduction of application specific ICs (ASICs) is expected to make systems smaller, costless, and give higher speed response. Today's in-vehicle information systems are reviewed function by function to discover what functions need to be implemented into ASICs for future systems, what ASICs will be required, and what technology has to be developed. It is concluded that more integration technology is expected including high parformance CPUs, large capacity memories, interface circuits, and some analog circuits such as DA converter. To develop this technology, some, major problems such as power consumption, number of input/output signals, as well as design aid and process technology are pointed out.

A fiextensional transmitter with a hinge-lever displacement amplifier has been developed. Investigation reults for the transmitter are reported. The transmitter has a two-stage displacement amplifier. The first-stage amplifier consists of a hinge-lever mechanism. The second-stage amplifier is a tapered oval shell. An electro-mechano-acoustical equivalent circuit is derived for the transmitter. The transmitter was designed, based on the equivalent circuit, and fabricated. For only the shell part, a modal analysis by a finite element method was applied and equivalent circuit constants were calculated. Transmitter dimensions are 36 cm in diameter and 25 cm in depth. The actually obtained resonant frequency is 400 Hz, and the mechanical quality factor is 6.2. A 188 dB source level re 1 µPa at 1 meter was obtained.

A power converter with a new piezoelectric transformer is presented. The piezoelectric transformer, made of lead titanate solid solution ceramic, is operated with a thickness extensional vibration mode. This transformer can operate at high frequency, over several megahertz, with about 90% high efficiency. The resonant frequency for the transformer is 2 MHz. The power converter with the transformer applies the theory for a class-E switching converter using an electromagnetic transformer. Maximum output power was obtained when the switching frequency was slightly higher than the resonant frequency. 4.4 W output power was successfully obtained with 52% efficiency at 2.1 MHz switching frequency.

A method has been investigated for calculating the material constants for piezoelectric ceramics under the one-dimensional stress, using a bolted Langevin resonator, which can apply compressive stress to the ceramics. For this method, the piezoelectric, dielectric and elastic constants under the static compressive stress can be determined, by measuring the resonant and antiresonant frequencies and the capacitance at constant stress for the resonator, in the same method as used under stress-free condition. Also, four types of lead zirconate titanate piezoelectric ceramics for transducers, NEPEC-1, NEPEC-6, NEPEC-63 and NEPEC-21, have been measured as a function of one-dimensional compressive stress parallel to the polar axis up to a 176 MPa maximum. The hysteresis loops for dielectric constants /ε0, electromechanical coupling factors k33, piezoelectric constants d33 and g33, and elastic constants and for these ceramics have been presented. These measurement results show inclinations analogous to those reported by Krueger and Meeks. The experimental feasibility and practicability of using a bolted Langevin resonator to measure the piezoelectric ceramic material constants have been established.

A 60-GHz CMOS transmitter with on-chip antenna for high-speed short-range wireless interconnections is presented. The radiation gain of the on-chip antenna is doubled using helium-3 ion irradiation technique. The transmitter core is composed of a resistive-feedback RF amplifier, a double-balanced passive mixer, and an injection-locked oscillator. The wideband and power-saving design of the transmitter core guarantees the low-power and high-data-rate characteristic. The transmitter fabricated in a 65-nm CMOS process achieves 5-Gb/s data rate with an EVM performance of $-$12 dB for BPSK modulation at a distance of 1,mm. The whole transmitter consumes 17,mW from a 1.2-V supply and occupies a core area of 0.64,mm$^{2}$ including the on-chip antenna. The gain-enhanced antenna together with the wideband and power-saving design of the transmitter provides a low-power low-cost full on-chip solution for the short-range high-data-rate wireless communication.

A 1.544 MHz timing-extraction ceramic filter is examined. This filter has been successfully introduced into a PCM carrier system. Second-order Gaussian approximated effective-parameter theory with gentle frequency-phase inclination characteristics is applied in the circuit design. A ladder transformer filter construction, employing two resonator units and a coupling capacitor, is adopted. A resonator unit, comprising a trapped-energy piezoelectric ceramic strip resonator operating in the width-shear vibration mode and a ceramic capacitor connected in series with the resonator, fulfils the function for easy frequency adjustment and temperature compensation of the resonant frequency. Filter input and output terminating resistances are 30 Ω and 1500 Ω, respectively. The 3 dB fractional bandwidth is 1.07% and the insertion loss at center frequency f0 is -4.8 dB. The frequency deviation of f0 is within 200 ppm over a -20 to 60 temperature range and the aging rate of f0 is about 0.01%/decade. The frequency deviation over the operating temperature range is less than one-third and the aging rate is about one-half of the conventional LC filter used for this application. The filter size is reduced to one-fifth that of the LC filter.

The construction method for ladder filters employing piezoelectric ceramic resonators, widely used in consumer radio communication equipments, is investigated with the object of obtaining low-cost high-performance filters. For the presented method, the resonant or antiresonant frequencies of the resonators included in a filter are staggered one after another, perceiving that a small difference in these frequencies between electrically adjacent resonators can be tolerated. The allowable frequency limits for this filter are about four times as great as those for a usual filter, designed using the image parameter or near-image parameter method. The filter can exhibit performances equal to the usual filter. The frequency adjustment process for resonators is able to be fairly well curtailed. Filters based on this construction method include ceramic filters for CB transceiver and pocket-bell receiver, which were designed and trially produced. As a result, low-ripple filters with rough frequency adjustment at most were obtained.

A wideband and high efficiency underwater ultrasonic transducer with a single acoustic matching plate has been presented. The transducer consists of a piezoelectric ceramic resonator, operating in unstiffened longitudinal mode, and a single acoustic matching plate bonded to the ceramic resonator. The matching plate is made of a Al2O3-epoxy composite. The ceramic resonator is T-shaped with a taper, where its polarized part is a thin rectangular bar, which can be driven with low voltage, and where its non-polarized parts comprise a horn part and a head part. The transducer has been designed based on a double mode filter synthesis theory, because it has two resonant modes, whose phases differ byπfrom each other. The optimum specific acoustic impedance and length for the matching plate have been calculated. The 30 kHz array, including four transducers supported at their vibrational nodes, has been fabricated and evaluated. As a result, it has been confirmed that the array has the following characteristics: 33% fractional bandwidth, 211.6 dB sound pressure level re lµPa at l meter,177 dB receiving voltage sensitvity re 1 V/µPa and possible operating depth over 3000 meters. Excellent agreement between theoretical values and experimental results has been obtained. It has been proved that this transducer is useful as a transducer with high resolution for deep oceans.

Low-profile inverter power supplies are increasingly required for backlight systems of liquid crystal displays (LCDs). A great deal of attention has been focused on the application of piezoelectric transformers (PTs) to such power supplies. To miniaturize PT inverters still further, PTs need to have sufficient high voltage-step-up-ratio, which can be achieved by a multilayered PT. First, this paper describes a method for simulating such performance using a distributed constant equivalent circuit model. The results of the simulation for a multilayered PT operated in the third order longitudinal vibration mode show that the resistance of internal electrodes causes the dominant loss factor. Next, a power inverter incorporating the multilayered PT was fabricated. This power inverter can be operated over a wide input DC voltage range from 7-20 V. Regarding a conventional inverter drive circuit, when input DC voltage range was extended, the inverter efficiency remarkably decreased. For the reason, we developed a new inverter circuit, which is equipped with an automatic drive voltage control circuit to maintain the drive voltage to the PT at a constant value. As a result, the fabricated power inverter exhibited more than 90% overall efficiency and 3.5 W output power, which is enough to light up a 12.1-inch color LCD. The maximum luminance efficiency on a light transmission plate of the backlight was as high as 30 cd/m2/W.

Wide-band, low-ripple underwater transducers with high-power acoustic radiation capability have been designed on the basis of multiple-mode filter synthesis theory. They are composed of triple acoustic matching plates and double backing plates with optimized specific acoustic impedances,besides piezoelectric ceramic elements. One of the backing plates employs a Fe damping-alloy to suppress unwanted response peaks in the frequency range above the passband region. Two 33 array transducers were fabricated, each with a center frequency of 200 kHz, one as a transmitter and the other as a receiver. The two transducers show high-sensitivity, low-ripple and wide-band transmitting and receiving responses. Then, the transducers were applied in a color video picture digital transmission system.Clear color video pictures, composed of 256240 pixels, were successfully received within one second.

The efficiency and reliability of an ultrasonic motor, operating in longitudinal-torsional degenerate-mode, are investigated. It is essential to miniaturize both longitudinal and torsional mode piezoelectric ceramic elements, in order to produce low-cost ultrasonic motors, and to realize a motor with low battery power consumption. The ultrasonic motor is designed with an accurate mechanical equivalent circuit, which can produce high design precision notwithstanding low computation cost. It is important in this design that the resonant frequencies of longitudinal mode and torsional mode coincide with each other under the pertinent rotor pressing force and longitudinal and torsional mode piezoelectric ceramic elements are located in the vibration nodes for the longitudinal mode and the torsional mode, respectively. As a result, the fabricated motor, whose rotor diameter was 12 mm, produced 480 r.p.m. no-load revolution speed, 0.55 kgfcm maximum torque, 50% maximum efficiency, 2.5 W consumed power and a lifetime over 1000 hours with continuous rotation.

Low-profile, miniaturized and highly efficient power inverters are required to light up backlights, which include cold cathode fluorescent lamps (CCFLs), in color liquid crystal displays (LCDs), replacing conventional power inverters with electromagnetic transformers. The object of this study is to actualize a power inverter to which a novel multilayered piezoelectric ceramic transformer operating in the third order longitudinal mode is applied. The piezoelectric transformer has a symmetrical structure in the lengthwise direction and its generating part operates in a piezoelectric stiffened mode in order to increase both energy conversion efficiency and power density. This transformer has great advantages. Namely, all the electronic terminals in this transformer can be connected at the vibration nodes of the transformer, which contributes to the guarantee of stable transformer performances at high power operation, and this transformer is superior in impedance matching against the backlight load at steady state, because the output impedance of this transformer is much lower than that of conventional Rosen type transformers. Then a power inverter with the transformer was fabricated. In this power inverter, a separately excited oscillation circuit was adopted to drive the transformer with high efficiency, and the transformer drive frequency was controlled by detecting the backlight current in order to adjust the backlight luminance properly. As a result, the fabricated power inverter exhibited more than 90% overall efficiency and 4. 5-W output power, which is enough power to light up a 9. 4 inch color LCD, including the stray capacitance loss resulting from CCFL mounting. The luminance value on a light transmission plate of the backlight was more than 2000 cd/m2.

This paper presents a new sort of multilayer piezoelectric ceramic transformer for switching regulated power supplies. This piezoelectric transformer operates in the second thickness extensional vibration mode. Its resonant frequency is higher than 1 MHz. First, numerical simulation was implemented using a distributed constant electromechanical equivalent circuit method. It was calculated that this piezoelectric transformer, which has higher than 200 mechanical quality factor Qm, could work with higher than 90% efficiency and in more than 20-W/cm3 high power density. Second, a trially fabricated transformer, which is 15 mm long, 15 mm wide and 2.2 mm thick, was examined. Modified PbTiO3 family ceramics were used for the piezoelectric transformer material, because of the large anisotropy between electromechanical coupling factors kt and kp. Obtained results indicate that the piezoelectric transformer has good resonant characteristics, with little spurious vibration, and exhibits 16-W/cm3 power density with high efficiency at 2 MHz. Moreover, a switching regulated power supply, applying the piezoelectric ceramic transformer, was built and examined.

A number of Tonpilz piezoelectric transducers generally form a large matrix array. They may be required to be only light in weight, or both miniaturized and light in weight as well as to have high-power capability, according to their use. This paper describes the results obtained in an investigation of miniaturized, light-weight Tonpilz piezoelectric transducers with high-power capability. An electromechanical energy conversion system and mechanical vibration system for the transducer are theoretically investigated on transducer configuration, using a Martin equivalent circuit and distributed-constant equivalent mechanical circuits. For simplification of the theoretical analysis, the transducer was considered as being divided into a front-half section, from the head mass end to the vibration nodal section, and a rear-half section, from the vibration nodal section to the tail mass end. Figures of merits, FMm for the front-half section and FM'm for the rear-half section, are calculated to achieve lightening as well as high-power capability. In addition, figures of merits FMml for the front-half section and FM'ml for the rear-half section are calculated to achieve miniaturization and lightening as well as high-power capability. To corroborate the theoretical results obtained, three kinds of Tonpilz transducers having the same 30 kHz resonant frequency but different configurations were built. Then, three kinds of 33 matrix arrays composed of nine Tonpilz transducers with the same configuration were fabricated. To evaluate the high-power characteristics for the arrays, a water tank to which high hydraulic pressure can be applied was adopted and a high-power test was carried out. As a result, it was found that transducers with high FMm and FM'm figures of merits are light in weight and exhibit high performance in high-power handling capability. Also, it was found that transducers with high FMml and FM'ml figures of merits are miniaturized and light in weight and exhibit high performance in high-power handling capability.

Tonpilz piezoelectric transducers are one style of transducers for high-power sound generation. However, the transducers have mainly been designed by the trial-and-error method. The object of this paper is to precisely estimate the transducer performances beforehand by a equivalent circuit analysis. The precise electro-mechano-acoustical equivalent circuit is derived for the transducer, including housing, an acoustic rubber layer and a bolt, and its transmission matrix is presented. To improve the calculation accuracy, the effects of adhesive layers in a piezoelectric ceramic stack part and compressive stress by bolting them together are included into the electrical and mechanical equivalent constants for the ceramic stack. Also, to accurately evaluate any errors between theoretical values and measured values, transducer performances are expressed as absolute values by MKS units. Then, based on this analysis, a Tonpilz transducer has been built. Transmitting and receiving voltage sensitivities for the transducer, as well as the respective resonant frequencies, mechanical quality factors and free admittance loci in air and in water, have been measured. As a result, a good agreement between theoretical values and experimental results has been achieved.