Capacitive-component reducing circuit in electrostatic-type transducer means
First Claim
1. A circuit comprising:
- an electrostatic-type transducer including a first terminal connected to ground and a second terminal connected to a drive power source, the electrostatic-type transducer having a damping capacitive component;
an amplifier having an input terminal coupled to the second terminal of the electrostatic-type transducer, andan electrostatic capacitor connected between an amplifying output terminal of the amplifier and the second terminal of the electrostatic-type transducer,wherein a gain of the amplifier and a capacitance of the electrostatic capacitor are selected such that the damping capacitive component of the electrostatic-type transducer is minimized.
0 Assignments
0 Petitions
Accused Products
Abstract
A drive voltage is supplied to a piezoelectric oscillator from an A.C. drive power source. Attached to an electrode of the piezoelectric oscillator is a loop circuit in which an amplifier having a (N+1) voltage amplification factor and an electrostatic capacitor are connected in series. When the electrostatic capacity is set to 1/N of a damping capacity of the piezoelectric oscillator, the current flowing through the damping capacity is replaced and shared by current from the electrostatic capacity, thus the drive current will not be consumed by the damping capacity. Therefore, a condition where the damping capacity is minimized depends on a capacity value of the electrostatic capacity and amplification factor of the amplifier only and does not depend on the frequency.
-
Citations
25 Claims
-
1. A circuit comprising:
-
an electrostatic-type transducer including a first terminal connected to ground and a second terminal connected to a drive power source, the electrostatic-type transducer having a damping capacitive component; an amplifier having an input terminal coupled to the second terminal of the electrostatic-type transducer, and an electrostatic capacitor connected between an amplifying output terminal of the amplifier and the second terminal of the electrostatic-type transducer, wherein a gain of the amplifier and a capacitance of the electrostatic capacitor are selected such that the damping capacitive component of the electrostatic-type transducer is minimized. - View Dependent Claims (2, 3, 4)
-
-
5. A drive apparatus for an electrostatic-type transducer driven by a drive power source, the apparatus comprising:
-
a path through which a drive power is supplied from the drive power source to a terminal of the electrostatic-type transducer; and a circuit for reducing a damping capacitive component of the electrostatic-type transducer, the circuit including an amplifier which amplifies voltage received at the terminal of the electrostatic-type transducer, and an electrostatic capacitor connected between an amplifying output end of the amplifier and the terminal of the electrostatic-type transducer wherein a gain of the amplifier and a capacitance of the electrostatic capacitor are selected such that the damping capacitive component of the electrostatic-type transducer is minimized; wherein the amplifier in the circuit for reducing the damping capacitive component is provided in a position where the drive power supplied to the electrostatic-type transducer via said path is amplified. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13)
-
-
14. A detection apparatus for an electrostatic-type transducer, the detection apparatus comprising:
-
an amplifier which amplifies a drive voltage applied to a first terminal of the electrostatic-type transducer; an electrostatic capacitor connected between an amplifying output terminal of the amplifier and a second terminal of the electrostatic-type transducer; and means for controlling a gain of the amplifier such that the amplifier and the electrostatic capacitor form a capacitive-component reducing circuit for minimizing a damping capacitive component of the electrostatic-type transducer. - View Dependent Claims (15, 16, 17)
-
-
18. A drive apparatus for an electrostatic-type transducer, comprising:
-
a frequency selection circuit including a capacitive component and resistance component of the electrostatic-type transducer; and an operational amplifier connected to said frequency selection circuit, wherein a portion of said frequency selection circuit is connected between an output and a non-inverting input of the operational amplifier to form a positive feedback loop, whereby self-oscillation occurs at a self-oscillation frequency determined by said frequency selection circuit. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25)
-
Specification