Electricity: measuring and testing – Magnetic – Displacement
Reexamination Certificate
2002-05-07
2004-12-07
Patidar, Jay (Department: 2862)
Electricity: measuring and testing
Magnetic
Displacement
C324S207150, C324S207240
Reexamination Certificate
active
06828780
ABSTRACT:
The present disclosure relates to the subject matter disclosed in German applications No. 101 24 483.5 of May 19, 2001 and No. 200 09 335.5 of May 24, 2000, which are incorporated herein by reference in its entirety and for all purposes.
BACKGROUND OF THE INVENTION
The invention relates to a position or path measuring system comprising a transmitter and a sensor which comprises at least one inductive element, to which the transmitter is coupled electromagnetically, wherein sensor and transmitter can be positioned relative to one another and the at least one inductive element is arranged on a support so as to be areally extended.
Position measuring systems of this type are used, for example, for measuring positions on pneumatic cylinders, for measuring the position of valves, in particular, in closed-loop control circuits or in gripping devices. It is very advantageous for such uses when a relative path between transmitter and sensor can be measured absolutely.
It is known from DE 42 05 957 A1 to provide a transmitter guide which is movable relative to a coil structure with a triangular attenuating surface consisting of an electrically conductive material, wherein the attenuation increases, the nearer the coil structure approaches the end of the attenuating surface which reaches over the entire width of the transmitter guide.
The object underlying the invention is to improve a position measuring system of the type specified at the outset in such a manner that a great number of possibilities for its use result.
SUMMARY OF THE INVENTION
This object is accomplished in accordance with the invention in that the support with the at least one inductive element is designed to be at least partially flexible.
The shape of the support may be varied due to its flexible design and, in particular, varied such that the support with the inductive element arranged thereon can be curved, i.e. can be brought into a shape which is not flat. For example, the support may, as a result, be adapted to contours of an object in order to be able to carry out a position determination in the case of curved path movements. If, for example, the support is adapted to the path curvature, the relative distance between the support and the transmitter may be kept constant even with a curved path movement and so the position determination is not influenced by any alteration in the relative distance, i.e. the sensor signal experiences in accordance with the invention a change solely due to the movement along the path direction and not along transversely to the path direction.
As a result of an at least partially flexible design of the support, the useful length range with respect to the position determination of the position measuring system is also increased, namely with the same length of a corresponding measurement section or with the same useful area the length of the corresponding measurement section is reduced: Edge areas of the inductive element influence the sensor signal so that a non-monotonic dependence of a characteristic value of the inductive element, such as factor Q or effective inductance, results, for example, at these areas. This means for the application that only a certain section of the inductive element can be used for the position determination and the edge areas outside this are necessary in order to provide the areally extended inductive element but, otherwise, increase the length of the system. In the case of a flexible design of the support, such edge areas can be bent away and, in particular, folded out of the measurement field so that the length of the measurement section can be reduced along the measurement direction. As a result, an increase in thickness is caused to a certain degree but this may be kept slight in that, for example, the edge sections bent away are folded or rolled behind the support.
It is advantageous when the at least one inductive element is imprinted on the support. As a result, an areal extension thereof may be provided in a simple manner and corresponding path conductors may also be produced so as to be thin so that a flexibility of the support is ensured at least in a section with the inductive element arranged thereon.
A flexible design of the support may be achieved in a simple manner when this comprises a flexible foil. The flexible foil is a printed circuit board foil, on which the inductive element is arranged. A foil has a bending flexibility parallel to its surface in its normal directions.
It is particularly advantageous when the support comprises a rigid support section and one or more flexible support sections which are arranged on the rigid support section. The flexible support sections may then be bent away from the rigid support section in order to move them out of the measurement field of the sensor. The length of the usable measurement range is then determined by the dimensions of the rigid support section.
It is advantageous when, for providing a usable measurement area with respect to the at least one inductive element, one or more edge sections of the support are arranged with respect to the measurement section of the support in such a manner that they are located outside a measurement field. The length dimensions of the measurement section in a position measuring direction determine the usable distance measuring area and also the outer dimensions of the sensor since the edge sections may be bent away from the measurement section and, therefore, contribute nothing or only little to the longitudinal extension of the sensor. The measurable path is then essentially determined by the length of the measurement section.
Due to the edge section or sections of the support, end edge areas of the at least one inductive element are favorably located outside the measurement field. Such end edge areas, such as, for example, the apexes of triangles in the case of a triangular flat coil as inductive element, influence the sensor signal since, on the one hand, a transition takes place at this point between an electromagnetically couplable area and an area which is not electromagnetically couplable and since, on the other hand, the winding density and also line directions, for example, differ more greatly at these edge areas than in the case of areas outside these edge areas.
It is favorable when the measurement section of the support is of a rigid design since the edge sections of the support may then be folded away in a simple manner and may also be positioned behind the measurement section in order to keep the thickness extension slight as a result of the edge sections being bent away.
The edge section or sections of the support are advantageously arranged so as to be flexible with respect to the measurement section in order to be able to bend them away from it. This may be achieved, for example, in that a flexible foil is arranged on a rigid subsupport which has essentially the dimensions of the measurement section. This flexible foil is then connected to the measurement section so that the support is rigid in this area. Outside the subsupport the measurement foil may be bent relative to it and therefore to the measurement section. An alternative possibility is to arrange the edge sections themselves on the measurement section so as to be flexible, for example, to arrange them on a rigid printed circuit board so as to be flexible.
It is, furthermore, favorable when an edge section is arranged on the measurement section so as to be bent away or to be bendable away from it in order to limit the usable measurement area essentially to the measurement section.
In order to keep the thickness dimensions transversely to the measurement direction small, the edge section or sections are favorably positioned behind the support in relation to a measurement field. On the one hand, they do not interfere with the measurement and, on the other hand, the corresponding thickness dimensions of the sensor are kept small. For this purpose, an edge section is, in particular, arranged so as to be rolled and, in particular, rolled behind the support or an edge section is arrange
Droxler Reinhard
Jagiella Manfred
BALLUFF GmbH
Lipsitz Barry R.
McAllister Douglas M.
Patidar Jay
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