Nihon Dempa Kogyo Co., Ltd.

Shigenori Watanabe

Shunichi Wakamatsu

Takeru Mutoh

Mitsuaki Koyama

Tomoya Yorita

Hiroyuki Kukita

Takayuki Ishikawa

Kazuo Akaike

Junichiro Yamakawa

Shigetaka Kaga

Tadashi Tamiya

Keisuke Miyashita

Chiaki Kato

Shuzi Osawa

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 shorten the time required for an oscillation frequency to stabilize in a sensing device sensing a substance to be sensed by using the fact that a natural frequency of a piezoelectric resonator changes when the substance to be sensed is adsorbed by an adsorption layer formed on the piezoelectric resonator. A sensing device includes: an oscillator circuitoscillating a quartz-crystal resonator; and an intense excitation circuit that is formed by the oscillator circuitincluding a series circuit of a resistorand a third transistorof PNP type and that intensely excites the quartz-crystal resonatorconnected to the oscillator circuitfor a period of time preset by a one-shot circuitby supplying the quartz-crystal resonatorwith high power equal to or more than twice regular power supplied at the time of the measurement of the substance to be sensed, to stabilize the oscillation of the quartz-crystal resonator. When the connection of the quartz-crystal resonatoris detected, the one-shot circuitbrings the oscillator circuitinto an aging state and the high power is supplied to the quartz-crystal resonatorto intensely excite the quartz-crystal resonator, thereby eliminating the distortion and stress of a quartz-crystal plate

There is provided a temperature compensated piezoelectric oscillator which excels in frequency stability and has a good electronic noise characteristic, and with which a circuit can be structured simply. An auxiliary oscillator unitsharing a crystal substratewith a main oscillator unitoutputting a set frequency fto an outside is used as a temperature detecting unitdetecting a temperature T for obtaining a compensation voltage &#x394;V in a temperature compensated piezoelectric oscillator (TCXO), and electrodesof the main oscillator unitand the auxiliary oscillator unitare provided separately on the crystal substrate. For example, a fundamental wave and an overtone are used or a thickness shear vibration and a contour shear vibration are used in the main oscillator unitand the auxiliary oscillator unit, respectively.

Piezoelectric oscillator

Bio-sensor

Crystal resonator for bio-sensor

A quartz crystal element in which unwanted response is suppressed, comprising a thickness shear quartz blank such as an AT-cut type. An area where an amplitude of unwanted response may be strong can be eliminated from the quartz blank by forming the quartz blank into a substantially hexagon. Preferably, each pair of three pairs of opposite sides are mutually parallel and one of the pairs is parallel to the longest diagonal line of the quartz blank. For an AT-cut type of quartz crystal element, the direction of the longest diagonal line of the quartz blank is within the range of 28.degree..+-.15.degree. or 118.degree..+-.15.degree. from the Z' axis direction of the quartz blank, and the quartz blank is held at the ends of the longest diagonal line.

Quartz crystal element using a thickness shear hexagonal quartz blank

Growing community of inventors

Saitama, Japan

Shigenori Watanabe