摘要:
In a directional loudspeaker, an audible sound signal that is modulated with a carrier wave in the ultrasonic wave band is input to a piezoelectric element, and thereby a diaphragm having the piezoelectric element is vibrated and a sound wave is generated. In such a directional loudspeaker, the diaphragm is fixed to a fixed part via a plurality of beams disposed along the outer circumference of the diaphragm.
摘要:
A sound reproduction device includes a superdirective speaker having a first surface, and an attachment part having a second surface opposed to the first surface. The first surface has a convex face, and the second surface has a concave face which can come into contact with the convex face. A curvature of the convex face is set larger than that of the concave face. A direction of emitting a sound wave of the superdirective speaker can be adjusted by making the convex face move along the concave face.
摘要:
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.
摘要:
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. Consequently, the effective coupling factor resulting from the electrode structure and the vibration mode can be kept high even if the capacitance is changed freely, and thus high element efficiency and a small amount of generated heat can be maintained and stress can be decreased.
摘要:
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.
摘要:
The invention provides a method of driving a piezoelectric transformer and a power source apparatus using the same. For a circuit for driving a piezoelectric transformer which steps up a voltage input from a primary electrode by a piezoelectric effect to output the stepped up voltage from a secondary electrode, the gradient (linear differential value) of a step-up ratio at the piezoelectric transformer is detected, and the detected gradient is used to control the driving frequency for the piezoelectric transformer so that the driving frequency approaches to the resonant frequency of the piezoelectric transformer.
摘要:
A driving method and a driving circuit for a piezoelectric transformer are capable of driving the piezoelectric transformer with high driving efficiency independently of an impedance change of a load such as a cold cathode tube by corresponding to the characteristic variance of the piezoelectric transformer, thereby also suppressing mechanical damage to be imposed on the piezoelectric transformer itself even if the load changes abruptly. The piezoelectric transformer is driven with a predetermined first frequency, and a power supply for a load connected to the secondary side of the piezoelectric transformer is started, and when an impedance of a load changes and reaches a predetermined impedance during the power supply, the driving frequency of the piezoelectric transformer is changed without a sweep from the first frequency to a predetermined second frequency. Furthermore, the second frequency is determined by detecting characteristics of the piezoelectric transformer before supplying the load steadily with electric power.
摘要:
A wafer with a reversed domain is prepared for two piezoelectric single crystal plates and of about the same thickness by using direct bonding without any adhesive. Driving electrodes are formed on two principal planes of the wafer with a reversed domain to provide a piezoelectric resonator. A piezoelectric resonator having the structure with a reversed polarization and using odd-order vibration modes vibrating with a fundamental wave has a wavelength of a thickness thereof and suppresses scattering of the thickness of the domains with a reversed polarization. In the direct bonding, the axes of the spontaneous polarization of the two piezoelectric single crystal plates are reverse to each other and crystalline axes other than the axes of polarization are shifted intentionally by an angle other than zero. Thus, spurious modes are suppressed in a simple way.
摘要:
An acceleration sensor includes: a piezoelectric vibrator including a piezoelectric element having a first principal surface and a second principal surface opposed each other, a first and a second electrode formed on the first and the second principal surface, and conductive protrusions made of a metal material or a ceramic material and formed by a thermal spraying process; and a holding body for holding the piezoelectric vibrator via the conductive protrusions.
摘要:
A wafer with a reversed domain is prepared for two piezoelectric single crystal plates 11 and 12 having about the same thickness as each other by using direct bonding without any adhesive. Then, driving electrodes 13 are formed on two principal planes of the wafer with a reversed domain to provide a piezoelectric resonator. A piezoelectric resonator having the structure with a reverses polarization and using odd-order vibration modes vibrating with a fundamental wave has a wavelength of a thickness thereof suppresses scattering of the thickness of the domains with a reversed polarization. In the direct bonding, the axes of the spontaneous polarization of the two piezoelectric single crystal plates are reverse to each other and crystalline axes other than the axes of polarization are shifted intentionally by an angle other than zero. Thus, spurious modes are suppressed in a simple way.