Measuring and testing – Dynamometers – Responsive to force
Reexamination Certificate
1998-04-03
2001-09-25
Fuller, Benjamin R. (Department: 2855)
Measuring and testing
Dynamometers
Responsive to force
Reexamination Certificate
active
06293160
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a load sensor and a pointing equipment incorporating the load sensor, built in, for example, game machines for their operating board, pointing device of personal computers, remote controllers of various electronic appliances, for inputting coordinates (two-dimensional) on a display screen by manipulating an operating rod in the front-rear and right-left directions.
BACKGROUND OF THE INVENTION
Among the conventional load sensors, a load sensor as disclosed in the Japanese Patent Laid-open No. 07-174646 is widely known.
FIG. 30
shows a perspective view of the conventional load sensor. An elastic board
1
is fixed at four corners to a base
3
with a fixing member
4
, and an operating rod
2
made of a rigid material is provided at the center of elastic board
1
. When the end of operating rod
2
is given with a force in parallel with the elastic board
1
, the elastic board
1
makes a deformation. In the areas between the operating rod
2
and the fixing member
4
, a pair of strain detecting elements
5
and
6
are provided respectively on lines connecting the fixing member
4
and the operating rod
2
forming right angles to each other at a same distance from the operating rod
2
, totalling two pairs; the first pair of strain detecting elements
5
comprising elements
5
A and
5
B, while the second pair of strain detecting elements
6
comprising elements
6
A and
6
B. These elements
5
A,
5
B,
6
A and
6
B are strain-responsive resistor elements and have a same value of resistance.
Operation of the load sensor is described referring to FIG.
31
. When the operating rod
2
is given at its end with a force in the direction P
1
that is parallel to the elastic board
1
and going towards element
5
A, the element
5
A makes, together with the elastic board
1
, a concave deformation, while the element
5
B a convex deformation. As a result of the deformation, the resistance value of element
5
A goes down, while that of element
5
B goes up. Through calculation of difference in the shift of resistance value between element
5
A and element
5
B, the shift of resistance value is doubled, and outputted to represent the force applied to. In the mean time, the elements
6
A and
6
B receive only a torsional stress of a same direction, and there is no difference in the shift of resistance value between elements
6
A and
6
B. Therefore, only a force in the direction of coordinate axis of the first pair of strain detecting elements
5
is detected.
When the operating rod
2
is given at its end with a force in the direction P
2
that is parallel to the elastic board
1
and going towards the middle point between element
5
A and element
6
A, the element
5
A and the element
6
A make a concave deformation, while the element
5
B and the element
6
B a convex deformation. As a result of the deformations, the resistance value of the elements
5
A and
6
A goes down, while that of the elements
5
B and
6
B goes up. The difference in the shift of resistance value between element
5
A and element
5
B of the first pair of strain detecting element
5
, and the difference in the shift of resistance value between element
6
A and element
6
B of the second pair of strain detecting element
6
are calculated respectively to compare the differences, and the strength and the direction of the force applied to are detected and outputted. In the way described above, a force applied to the operating rod
2
is split into the elements of two coordinate axes, and the strength and direction are detected.
The conventional load sensors, however, carry with them tasks for improvement with respect to the ease of operation, in the following points.
Point
1
is that a load sensor is employed only as means for moving cursor on a display screen, and an execute switch is provided separately. An operator has to move his or her fingers to the execute switch every time when to make execute action.
Point
2
is that an operating rod is protruding for a certain length in excess of an overall contour shape of an appliance. This is a limiting factor in designing an appliance slim. Also, such an operating rod is readily affected by an external force, and could easily be deformed if the force is big.
Point
3
is that an expensive ceramic plate or enamel plate is used for the elastic board, and that the operating load-output voltage level relation of a load sensor is determined only by stiffness of the elastic board. Which means that the designing freedom is limited, and it is not easy to meet the diversifying requirements of customers swiftly and economically.
SUMMARY OF THE INVENTION
The present invention offers an easy-to-use load sensor.
An exemplary embodiment of the invented load sensor comprises an elastic board having at least two strain detecting elements, an operating portion having a through hole positioned at the center of the elastic board, a base on which the elastic board is to be fixed at the edges, and an operating rod inserted in the through hole.
Preferably, a switch is provided under an operating rod inserted through the through hole of the elastic board. With such structure, an action for applying a force in parallel with the elastic board and an action of applying a vertical force for operating the switch may be conducted by an operator without changing the position of hand. This contributes to improve the efficiency of operation significantly.
Preferably, a spring is provided for always pushing an operating rod inserted through a through hole up, or a lock mechanism is provided for having an operating rod stop at a predetermined position within a range of up/down movement of the operating rod. With such structure, an operating rod is normally kept popped-out for the ease of manipulation, while it can be shrunk for storage when it is out of use to avoid possible deformation. Also, the overall height of a load sensor may made lower.
In a still other embodiment, an elastic insulating resin substrate overlaid together for reinforcement with an elastic metal sheet is employed for the elastic board. Under such a structure, any desired combinations of the operating load—the output voltage property may be established easily by changing the material, shape, thickness etc. of the reinforcing sheet to be coupled with a certain substrate. Furthermore, because this makes it possible to use any of insulating resin materials in combination with any of elastic metal materials readily available in the market, an inexpensive load sensor may be offered.
REFERENCES:
patent: 4064744 (1977-12-01), Kistler
patent: 4876524 (1989-10-01), Jenkins
patent: 5231386 (1993-07-01), Bradenburg et al.
patent: 5361642 (1994-11-01), Welch
patent: 5499041 (1996-03-01), Bradenburg et al.
patent: 5657051 (1997-08-01), Liao
patent: 5705778 (1998-01-01), Matsui et al.
patent: 0663 648 A2 (1995-07-01), None
patent: 0717 424 A2 (1996-06-01), None
patent: 59-210603 (1984-11-01), None
patent: 7-174646 (1995-07-01), None
patent: 07174646 (1995-07-01), None
patent: 08087375 (1996-02-01), None
European search report for application No. 98105365.5 dated Aug. 14, 1998.
Fuller Benjamin R.
Matsushita Electric - Industrial Co., Ltd.
Ratner & Prestia
Thompson Jewel V.
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