Nihon Dempa Kogyo Co., Ltd.

Takeru Mutoh

Mitsuaki Koyama

Shigenori Watanabe

Shunichi Wakamatsu

Hiroki Iwai

Hiroyuki Kukita

Ryoichi Ichikawa

Tomoya Yorita

Kazuo Akaike

Shinichi Sato

Takeshi Matsumoto

Yoshiaki Amano

Manabu Ishikawa

Junichiro Yamakawa

Toshihiko Kagami

A technique for detecting external force applied to a piezoelectric plate is provided. A crystal plate is cantilever-supported in a container. Excitation electrodes are formed on an upper face and lower face, respectively, of the crystal plate. A movable electrode is formed on the lower face side. A fixed electrode is provided on a bottom portion of the container facing the movable electrode. The excitation electrode on the upper face side and the fixed electrode are connected to an oscillation circuit. When the crystal plate bends by external force applied, capacitance between. A direction of the movable electrode along a length direction of the crystal plate is set to 30&#xb0; to 60&#xb0;, relative to a face orthogonal to an intended direction of the external force. The movable electrode and fixed electrode changes, and this capacitance change and a deformation of the crystal circuit.

External force detecting method and external force detecting device

A device is provided for a detecting external force applied to piezoelectric piece. A crystal piece is cantilever-supported in a container. Excitation electrodes are formed on an upper face and lower face, respectively. A movable electrode, connected via a lead-out electrode to the excitation electrode, is formed on the lower face side at a front end of the crystal piece. A fixed electrode is provided on a bottom portion of the container to face this movable electrode. The excitation electrode on the upper face side and the fixed electrode are connected to an oscillation circuit. When the crystal piece bends in response to an applied external force, capacitance between the movable electrode and fixed electrode, changes. This capacitance change results in a corresponding change in oscillation frequency of the crystal piece.

External force detecting device and external force detecting sensor

An acceleration measuring apparatus that can easily detect acceleration with high accuracy is provided. In the apparatus, positional displacement of a swingable pendulum member is detected, feedback control is performed to maintain the pendulum member in a stationary state using an actuator, and acceleration is measured by measuring the output of the actuator at this time. A movable electrode is provided to the pendulum member, and a loop is formed in which a fixed electrode provided to oppose the movable electrode, and an oscillating circuit, a crystal unit, and the movable electrode are electrically connected in series. By measuring an oscillating frequency of the oscillating circuit at this time, a change in the size of a variable capacitance formed between the movable electrode and the fixed electrode is detected, and thereby the positional displacement of the pendulum member is detected.

Acceleration measuring apparatus

In an external force detection apparatus, a crystal plate is cantilevered within a container. Excitation electrodes are formed on the top surface and the bottom surface of the crystal plate. A movable electrode is formed on a distal end on the bottom surface of the crystal plate and is connected to the excitation electrode on the bottom surface via an extraction electrode. A fixed electrode is provided on the bottom of the container to oppose the movable electrode. The excitation electrode on the top surface and the fixed electrode are connected to an oscillating circuit. When an external force acts on the crystal plate to bend it, the capacitance between the movable electrode and the fixed electrode changes, and this capacitance change is captured as a change in the oscillating frequency of the crystal plate.

External force detection apparatus and external force detection sensor

A crystal resonator comprises a first vibrating region provided on a crystal wafer, a second vibrating region provided on the crystal wafer, the second vibrating region having a different thickness and positive/negative orientation of the X-axis from those of the first vibrating region, and excitation electrodes which are provided respectively on the first vibrating region and the second vibrating region for causing the vibrating regions to vibrate independently. Frequencies that change by different amounts from each other relative to a temperature change can be retrieved from one vibrating region and the other vibrating region. Thus, based on an oscillating frequency of the vibrating region in which a clear frequency change occurs relative to the temperature, the oscillating frequency of the other vibrating region can be controlled. Thereby, increases in the complexity of the crystal oscillator can be suppressed.

Crystal resonator and crystal oscillator

Provided is a device capable of easily and accurately detecting a vibration period when, for example, an earthquake occurs. When a quartz-crystal plate bends upon application of a force, capacitance between a movable electrode provided at its tip portion and a fixed electrode provided on a vessel to face the movable electrode changes, so that an oscillation frequency of the quartz-crystal plate changes according to this capacitance. Therefore, when the vessel is vibrated, there appear a first state where the quartz-crystal plate ends to approach the fixed electrode and a second state where the quartz-crystal plate is in an original state or bends to be apart from the fixed electrode. Accordingly, an oscillation frequency corresponding to the first state and corresponding to the second state alternately appear, and therefore, it is possible to find the period (frequency) of the vibration.

Vibration detecting device

To provide a sensing device using a piezoelectric sensor having an oscillation area for detection and an oscillation area for reference and capable of achieving a high measurement sensitivity by improving shapes of excitation electrodes. On a quartz-crystal piece, there are provided strip-shaped left side area and right side area which are formed symmetrically to be separated from each other into left and right with respect to a center of a circlebeing a contour of a planar shape of a reaction channeland extend in a longitudinal direction in a parallel manner. Each of the areas is set to have a size in which both corner portionson the left side of the left side area and both corner portionson the right side of the right side area protrude to the outside of the circle, the corner portionsthat protrude to the outside are cut to make the left side area and the right side area position inside of the circle, and an excitation electrodefor measurement and an excitation electrodefor reference are respectively formed on the right side area and the left side area.

Sensing device

Objects of the present invention is to provide a piezoelectric resonator having high frequency stability and a sensing sensor using the piezoelectric resonator. In the present invention, a piezoelectric resonator 1 has: a first oscillation area 105 which is provided in a piezoelectric piece 100 and from which a first oscillation frequency is taken out; a second oscillation area which is provided in an area 105 different from the first oscillation area 106 via an elastic boundary area 107 and from which a second oscillation frequency is taken out; and excitation electrodes 101 to 103 provided on one surface side and another surface side of the oscillation areas 105, 106 across the piezoelectric piece 100, and a frequency difference between the first oscillation frequency and the second oscillation frequency is not less than 0.2% nor greater than 2.2% of these oscillation frequencies.

Piezoelectric resonator and sensing sensor

To provide a piezoelectric sensor in which a first electrode for measurement and a second electrode for reference are provided apart from each other on one surface side of a piezoelectric piece and a common electrode is provided on an opposite surface side so as to face the first and second electrodes. A piezoelectric sensor includes: a first electrode for measurement and a second electrode for reference provided apart from each other on one surface side of a piezoelectric piece; a common electrode provided on an opposite surface side of the piezoelectric piece commonly for the first electrode and the second electrode to face the first electrode and the second electrode; and an adsorption layer formed on an area, of the common electrode, to which the first electrode is faced across the piezoelectric piece, to adsorb a substance to be sensed.

Growing community of inventors

Sayama, Japan

Takeru Mutoh