Measuring and testing – Specimen stress or strain – or testing by stress or strain... – Specified electrical sensor or system
Reexamination Certificate
2000-12-05
2003-03-11
Noori, Max (Department: 2855)
Measuring and testing
Specimen stress or strain, or testing by stress or strain...
Specified electrical sensor or system
Reexamination Certificate
active
06530283
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a force sensor and, more particularly, to a force sensor which also functions as a push-button switch.
Push-button switches are used as input means to input ON/OFF information into a variety of electric appliances. In particular, low priced push-button switches employing silicon rubber have been widely used as operational buttons in various remote controllers, cellular phones, game machines, etc. In such types of push-buttons, a bowl-shaped silicon rubber is arranged upside down on an electronic circuit board and the bottom of the bowl is depressed to contact with the electrode pattern on the circuit board. The state of contact is detected electrically to thereby recognize the ON/OFF state. The push-button switch of such a type can provide a long stroke that corresponds to the height of the bowl-shaped portion. The switch also can provide a unique click feeling obtained by the elastic deformation of the bowl-shaped silicon rubber. Thus, this makes it easier for an operator to intuitively recognize through the sense of touch as to whether it is in the ON or OFF state, thereby providing highly favorable operability.
On the other hand, force sensors have also been used as devices that convert the operational inputs of operators to electrical signals. Force sensors can input operational amounts having a predetermined dynamic range as the magnitude of a force applied by the operator, while the push-button switch described above can only input ON/OFF information. Two-dimensional or three-dimensional force sensors are also used which are capable of decomposing an applied force into directional components to detect the force. In particular, capacitance-type force sensors have been used in various fields since the sensors provide the advantages of simplified structure and reduced cost. The sensor has a capacitance element formed of two electrodes to detect force based on the change in capacitance resulting from the change in spacing between the two electrodes. For example, capacitance-type multidimensional force sensors are disclosed in Japanese Laid Open Patent Publication No. 4-148833 of 1992, No. 4-249726 of 1992, No. 4-299227 of 1992, No. 4-337431 of 1992.
As described above, push-button switches and force sensors have been used in different applications, but devices having both functions are expected to be in demand in the coming years. For example, as an input device for use with game machines, a device is used having a push-button switch and a force sensor, which are separately incorporated into the device. Here, the push-button switch is to input ON/OFF information and the force sensor (i.e., the so-called “joy-stick”) is to perform operational input in multidimensional directions. However, in order to improve operability, the magnitude of an applied force as well as the ON/OFF operational input can be preferably detected by means of a single device.
An object of the present invention is to provide a force sensor that can recognize the magnitude of predetermined directional components of an applied force, while providing the function of a push-button switch that detects ON/OFF operational input. A further object of the present invention is particularly to provide a force sensor which provides a sufficient stroke and favorable click feeling to serve as a push-button and provides reduced cost as well.
According to the present invention, a force sensor is realized which detects a magnitude of a predetermined directional component of an applied force, while functioning as a push-button switch that detects the operational ON/OFF input.
SUMMARY OF THE INVENTION
(1) The first feature of the present invention resides in a force sensor comprising:
a circuit board arranged at a position where an upper surface thereof is contained in an X-Y plane when an XYZ three-dimensional coordinate system is defined;
an acting body attached to the upper surface of the circuit board, the acting body having a displacement portion arranged above the circuit board and displaced when an external force is applied thereto, a securing portion fixed to the circuit board, and a connecting portion for connecting the displacement portion to the securing portion;
an elastic deformation body, formed on a lower surface of the displacement portion and having elastic deformation properties;
a switch displacement electrode formed on a lower surface of the elastic deformation body;
a switch securing electrode formed on a position opposite to the switch displacement electrode on the circuit board; and
a capacitor adapted to produce a variation in capacitance caused by a displacement of the displacement portion;
wherein the connecting portion has flexibility so that when a force is applied to the displacement portion, a deflection is produced in the connecting portion, thereby causing a displacement in the displacement portion relative to the circuit board;
wherein when no force is applied to the displacement portion, the switch displacement electrode and the switch securing electrode are not kept in contact with each other, and when a force of a predetermined amount, directed in a Z-axis direction of the coordinate system, is applied to the displacement portion, the switch displacement electrode and the switch securing electrode are brought into contact with each other;
wherein when a further force, directed in the Z-axis direction, is applied to the displacement portion, the elastic deformation body is elastically deformed, thereby allowing capacitance of the capacitor to vary, with the contact state kept unchanged between the switch displacement electrode and the switch securing electrode; and
wherein a switch is composed of the switch displacement electrode and the switch securing electrode, and a contact state therebetween is electrically detected to thereby recognize the state of the switch and a change in capacitance of the capacitor is electrically detected to thereby recognize a magnitude of a predetermined directional component of a force applied.
(2) The second feature of the present invention resides in a force sensor according to the first feature:
wherein an acting body having a bowl-shaped portion is prepared and attached to the upper surface of the circuit board to be upside down, to use a portion corresponding to a bottom of the bowl as a displacement portion, to use a portion corresponding to a side of the bowl as a connecting portion, and to use a portion corresponding to a mouth of the bowl as a securing portion.
(3) The third feature of the present invention resides in a force sensor according to the second feature:
wherein an intermediate displacement board is disposed between the circuit board and the acting body so that a part of the intermediate displacement board is secured to the circuit board as a displacement board securing portion and another part of the intermediate displacement board constitutes a displacement board displacement portion for generating a displacement caused by a displacement in the displacement portion or a deformation in the connecting portion; and
a capacitor securing electrode formed on the circuit board and a capacitor displacement electrode formed on the displacement board displacement portion constitute a capacitor.
(4) The fourth feature of the present invention resides in a force sensor according to the third feature:
wherein a flexible plate having a bowl-shaped portion constitutes the intermediate displacement board, the intermediate displacement board being attached to the upper surface of the circuit board so as to arrange the bowl-shaped portion upside down, an open window being formed for allowing the elastic deformation body to penetrate therethrough on a portion corresponding to a bottom of the bowl, a portion surrounding the open window constituting the displacement board displacement portion, a portion corresponding to a mouth of the bowl constituting the displacement board securing portion, and the displacement portion or the connecting portion being brought into physical contact with the displ
Morimoto Hideo
Okada Kazuhiro
Taniguchi Nobumitsu
Ladas & Parry
Noori Max
Wacoh Corporation
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