Measuring and testing – Liquid level or depth gauge – Immersible electrode type
Reexamination Certificate
2001-02-22
2004-11-30
Williams, Hezron (Department: 2856)
Measuring and testing
Liquid level or depth gauge
Immersible electrode type
C073S30400R, C361S284000, C324S658000, C340S620000
Reexamination Certificate
active
06823730
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a capacitive fill level measurement device with a fill level sensor which has several sensor fields, with electrical wires connected to the sensor fields of the fill level sensor, with a selector switch connected by its multipole side to ends of the wires away from the sensor fields of the fill level sensor, and with a power supply and evaluation circuit which is connected to the monopole side of the selector switch, the sensor fields of the fill level sensor being made planiform and located on top of one another, and consisting preferably of metal.
2. Description of the Related Art
Capacitive fill level measurement devices are used for capacitive acquisition of the fill level of liquids, bulk materials and other loads in a closed or an open container and are common (compare, for example, German patent publication DE 196 44 777, European patent disclosure documents 0 916 930, 0 926 474, French patent disclosure document FR 2 662 249, U.S. Pat. Nos. 3,935,739, 4,350,039, 4,350,040, 4,589,077, 4,780,705, 5,142,909 and 5,406,843).
In capacitive fill level measurement devices, in terms of measurement engineering, the fact is often used that the load with a fill level which is to be determined influences the capacitance between the fill level sensor or between a sensor field of the fill level sensor on and a conventional reference electrode. This is because the dielectric constant of the load, which is also important for the capacitance between the fill level sensor or between one sensor field of the fill level sensor and the reference electrode differs from the dielectric constant of air. Consequently, as described above, capacitive fill level measurement devices of the type under consideration here as dictated by the needs of operation include a fill level sensor which has several sensor fields, a power supply and evaluation circuit.
As necessary, the sensor fields of the fill level sensor can be connected to the power supply and the evaluation circuit. This is done by the electrical wires which are connected to the sensor fields of the fill level sensor and the selector switch, which is connected by its multipole side to the ends of the wires away from the sensor fields of the fill level sensor, and the power supply and evaluation circuit is connected to its monopole side. The selector switch, therefore, as dictated by the requirements of operation on the one side, called the multipole side, has a plurality of terminals, while on the other side, called the monopole side, there is only one terminal; the selector switch therefore makes it possible to electrically connect one selectable terminal of the multipole side to the terminal of the monopole side or vice versa.
In examining the power supply and evaluation circuit in functional terms, it includes a power supply circuit and an evaluation circuit; while the power supply circuit is used to make available the necessary power supply voltage and the necessary power supply current to the fill level sensor, using the evaluation circuit the fill level of the load is determined, therefore, it is determined which sensor field of the fill level sensor has already been or is no longer being or has not yet reached by the load. With reference to the selector switch which can be made, for example, as a multiplexer (compare German patent publication DE 196 44 777) it can be stated that for the power supply function the power supply and evaluation circuit can be connected from the terminal of the monopole side to the terminal of the multipole side, while for the evaluation function the sensor field of the fill level sensor can be connected via the terminal of the multipole side and the terminal of the monopole side to the power supply and evaluation circuit.
It was stated initially that in the capacitive fill level measurement device underlying the invention (compare German patent publication DE 196 44 777), the sensor fields of the fill level sensor are made planiform and are located on top of one another and consist preferably of metal. Here planiform does not mean that the sensor field should be made essentially only two-dimensionally, but rather, only that the two-dimensional execution is significant, because for determining the fill level a change of the capacitance between a sensor field which acts as the measurement electrode and a conventional reference electrode is significant. The sensor elements are located on top of one another with respect to the fact that the fill level of a load located in a vessel is to be determined means only that the sensor fields is their geometrical extension are in any case also located on top of one another. Accordingly, the sensor fields can also be located next to one another and also overlapping on top of and/or next to one another. Ultimately, the sensor fields of the fill level sensor need not consist of metal; what is important with respect to material is in turn that each sensor field must be suitable as a measurement electrode, therefore must be suitable for accomplishing a capacitance which is changed by a changing dielectric constant, together with only one electrode.
SUMMARY OF THE INVENTION
An object of the invention is to devise a capacitive fill level measurement device of the type under consideration and described above, which can be manufactured with simple production technology and economically for a host of different applications and/or which largely meets the requirements of today in terms of electricity.
The capacitive fill level measurement device in accordance with the present invention is characterized by either electrical-mechanical, electrical-construction, or electrical-geometrical measures, and, in addition to the sensor fields which are located on top of one another, on one side or on both sides there includes a matrix of printed conductors which run vertically and horizontally, each horizontally running printed conductor on one side is connected to one sensor field and on the other side to a vertically running printed conductor, and each horizontally running printed conductor with the vertically running printed conductor which is connected to it forms an electrical line or a part of an electrical line.
It is important for the capacitive fill level measurement device in accordance with the present invention has a fill level sensor which is made such that the individual sensor fields are implemented, activated or connected to the electrical wires, or are provided with electrical wires in manner which is advantageous over conventional prior art devices. The special fill level sensor built in accordance with the present invention consists mainly in that the matrix provided next to the sensor fields including horizontally and vertically running printed conductors makes it possible to use a starting material for the fill level sensor which can be used for a host of different applications, in particular, different fill level measurement devices.
One such starting material which includes a conductor support, made preferably planiform, of a plurality of sensor fields which are made on top of one another in one plane parallel to the plane of the conductor support, which are made planiform and which are provided on the conductor support. and a matrix which is provided next to the sensor fields, on one side or on both sides, consisting of horizontally and vertically running printed conductors, all horizontal printed conductors with all vertical printed conductors being connected to one another so that all horizontal printed conductors and all vertical printed conductors are electrically connected to one another.
In the above described starting material for a fill level sensor, has several sensor fields, therefore, the sensor fields, horizontal printed conductors and vertical printed conductors are electrically connected to one another. In addition, the sensor fields, horizontal printed conductors and vertical printed conductors are at the same potential, this, of course, is not functionally
Buck Bernd
Gundlach Jochen
Palata Jaromir
i f m electronic GmbH
Jackson André K.
Nixon & Peabody LLP
Safran David S.
Williams Hezron
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