Measuring and testing – Dynamometers – Responsive to multiple loads or load components
Reexamination Certificate
2002-09-19
2004-08-24
Lefkowitz, Edward (Department: 2855)
Measuring and testing
Dynamometers
Responsive to multiple loads or load components
Reexamination Certificate
active
06779408
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a force detector and an acceleration detector to which the force detector is applied, and more particularly to a detector suitable for detection of multidimensional force or acceleration components. Further, this invention provides a method suitable for mass producing such detectors.
In the automobile industry or the machinery industry, there has been increased demand for detectors capable of precisely detecting a physical quantity such as force, acceleration or magnetism. Particularly, it is required to realize small, detectors capable of detecting physical quantities every respective two-dimensional or three-dimensional components.
To meet such a demand, there has been proposed a force detector in which gauge resistors are formed on a semiconductor substrate such as silicon, etc. to transform a mechanical distortion produced in the substrate on the basis of a force applied from the external to an electric signal by making use of the piezo resistive effect. When a weight body is attached to the detecting unit of the force detector, an acceleration detector for detecting, as a force, an acceleration applied to the weight body can be realized. Further, when a magnetic body is attached to the detecting unit of the force detector, a magnetic detector for detecting, as a force, a magnetism exerted on the magnetic body can be realized.
For example, in U.S. Pat. Nos. 4,905,523, 4,967,605, 4,969,366, U.S. patent application Ser. Nos. 07/362,399, 07/470,102, 07/559,381, force detectors using gauge resistor, acceleration detectors, and magnetic detectors are disclosed. Further, in U.S. patent application Ser. No. 07/526,837, a manufacturing method suitable for these detectors is disclosed.
Since there generally exists temperature dependency in the gauge resistance or the piezo resistive coefficient, in the case of the above described detectors, if there occurs any change in the temperature of the environment where those detectors are used, a detected value would include an error. Accordingly, it is required for carrying out a precise measurement to conduct temperature compensation. Particularly, in the case where such detectors are used in the field of automotive vehicle, etc., temperature compensation is required over the considerably broad operating temperature range of −40 to +12° C.
In addition, in order to manufacture the above described detectors, a high level process for processing the semiconductor substrate is required, and a high cost apparatus such as an ion implanter is also required. For this reason, there is the problem that the manufacturing cost becomes high.
SUMMARY OF THE INVENTION
A first object of this invention is to provide a novel detector which can detect a physical quantity such as force, acceleration or magnetism, etc. without carrying out temperature compensation, and can be supplied at a low cost.
A second object of this invention is to provide a manufacturing method suitable for mass production of such a novel detector.
1. Feature Relating to the Detector
To attain the above described first object, the detector according to this invention is featured as follows:
(1) The first feature resides in a force detector comprising:
a flexible substrate including a fixed portion fixed to a detector casing, a working portion to which a force from the external is transmitted, and a flexible portion having flexibility formed between the fixed portion and the working portion,
a fixed substrate fixed on the detector casing so as to face the flexible substrate,
a working body adapted to receive a force from the external to transmit this force to the working portion of the flexible substrate,
a displacement electrode formed on the surface facing to the fixed substrate of the flexible substrate, and
a fixed electrode formed on the surface facing to the flexible substrate of the fixed substrate,
wherein any one of the displacement electrode and the fixed electrode, or both the electrodes are constituted by a plurality of electrically independent localized electrodes to form a plurality of capacitance elements by electrodes opposite to each other to detect a force exerted on the working body every multidimensional respective components on the basis of changes in the electrostatic capacitance values of the respective capacitance elements.
In the force detector having the above mentioned first feature, when a force from the external is applied to the working body, the flexible substrate bends, so a distance between the displacement electrode and the fixed electrode varies. Accordingly, an electrostatic capacitance between both electrodes varies. Because the change of the electrostatic capacitance is dependent upon a force applied from the external, detection of force can be made by detecting the change of the electrostatic capacitance. In addition, at least one of the displacement electrode and the fixed electrode is constituted by a plurality of localized electrodes. A change of an electrostatic capacitance of a capacitance element formed by a localized electrode is dependent upon a direction of a force exerted and a position of the local electrode. Accordingly, changes in electrostatic capacitance values of a plurality of capacitance elements formed by a plurality of localized electrodes include information relating to a direction of the force exerted. Thus, the force exerted can be detected every multidimensional respective components.
(2) In the force detector having the above described first feature, the second feature resides in a force detector,
wherein any one of the displacement electrode and the fixed electrode, or both the electrodes are constituted by four groups of localized electrodes arranged in positive and negative directions of a first axis and a second axis perpendicular to each other on the surface where the localized electrodes are formed (hereinafter referred to as the electrode formation surface), thus to form four groups of capacitance elements by using the four groups of localized electrodes, respectively,
a force component in the first axis direction being detected by a difference between electrostatic capacitance values of capacitance elements belonging to the two groups of capacitance elements on the first axis of the four groups of capacitance elements,
a force component in the second axis direction being detected by a difference between electrostatic capacitance values of capacitance elements belonging to the two groups of capacitance elements on the second axis of the four groups of capacitance elements.
In the force detector having the above described second feature, four groups of localized electrodes are formed. When the electrode formation surface is defined as an XY plane, respective groups are formed on the both positive and negative, sides of the X-axis and on the positive and negative sides of the Y-axis, respectively. When a force in the X-axis direction is exerted on the working body, since the electrostatic capacitance values with respect to the both groups positioned on the positive and negative sides of the X-axis complementarily changes, it is possible to detect a force in the X-axis direction by the difference between electrostatic capacitance values with respect to the both groups. Similarly, by the difference between electrostatic capacitance values with respect to the both groups positioned on the positive and negative sides of the Y-axis, it is possible to detect a force in the Y-axis direction.
(3) In the force detector having the above described first feature, the third feature resides in a force detector,
wherein anyone of the displacement electrode and the fixed electrode or both the electrodes are constituted by four groups of localized electrodes arranged in positive and negative directions with respect to a first axis and a second axis perpendicular to each other on the electrode formation surface to form four groups of capacitance elements by using four groups of localized electrodes, respectively,
a force component in the first axis direction being detecte
Ladas & Parry
Lefkowitz Edward
Thompson Jewel V.
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