EP0237171A2
Expired / Lapsed
EP
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Inductance divider sensor
Assignee: Eldec Corp
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Filing: 1987-02-03
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Granted: —
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Expires: 2007-02-03
Abstract
Abstract A method and apparatus for sensing the proximity of a target object includes a sensor inductor (L s , 38) connected in series with an identical reference inductor (L R , 36) between an input and ground to form an inductive divider network. The sensor inductor is positioned so that its inductance can be varied in response to the proximity of a target object (14, 40) while the inductance of the reference inductor remains constant. Voltage pulses are periodically applied to the divider network from a source (32, 34) and divide across the reference and sensor inductors in accordance with the ratio of the inductances, as varied or not by the presence of the target object. A detector (30) monitors the output of the divider network and provides a target status signal indicative of the proximity of the target object. For low-power operation, the detector circuit and conductive divider network are periodically and momentarily energized in synchronism. This enables configuration of a self-contained, leadless proximity sensor having a battery power source and an optical output.
Inventors
- 👤 Bernard J. Burreson
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 02:52
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/94; H03K17/945; H03K17/95; H03K17/952; H03K17/9537
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
109 words
A proximity sensor comprising: an inductive divider network having a reference inductor and a sensor inductor connected in series between an input and ground to receive a voltage signal, said network having an output at the junction between said inductors, said sensor inductor having an inductance that varies in a predetermined manner with the proximity of a target object thereto; means for applying an input voltage to the input of said inductive divider network to produce an output voltage at the output thereof; and detector means responsive to said output voltage for providing a target status signal indicative of the proximity of the target object to said sensor inductor.
Claim 2
Dependent Claim
109 words
A proximity sensor comprising: an inductive divider network having a reference inductor and a sensor inductor connected in series between an input and ground to receive a voltage signal, said network having an output at the junction between said inductors, said sensor inductor having an inductance that varies in a predetermined manner with the proximity of a target object thereto; means for applying an input voltage to the input of said inductive divider network to produce an output voltage at the output thereof; and detector means responsive to said output voltage for providing a target status signal indicative of the proximity of the target object to said sensor inductor.
Claim 3
Dependent Claim
32 words
The proximity sensor of Claim 1, wherein said reference inductor has an inductance that remains substantially constant as the inductance of said sensor inductor varies with the proximity of the target object.
Claim 4
Dependent Claim
26 words
The proximity sensor of Claim 1, wherein said reference inductor has an inductance that varies in a predetermined manner with the proximity of said target object.
Claim 5
Dependent Claim
27 words
The proximity sensor of Claim 1, wherein said means for applying comprises pulse means for applying a voltage pulse to the input of said inductive divider network.
Claim 6
Dependent Claim
17 words
The proximity sensor of Claim 4, wherein said sensor inductor and reference inductor have equal characteristic inductances.
Claim 7
Dependent Claim
69 words
The proximity sensor of Claim 5, wherein said sensor inductor comprises a sense coil and said reference inductor comprises a reference coil, said sense and reference coils being wound upon a core and arranged and connected with one another such that a given external magnetic field induces a current in each of said coils, the current induced in said sense coil cancelling the current induced in said reference coil.
Claim 8
Dependent Claim
55 words
The proximity sensor of Claim 4, wherein said pulse means applies a voltage pulse having a predetermined duration during each one of a plurality of successive system periods and wherein said detector means is energized during each of said system periods in synchronism with the application of the voltage pulse to said inductive divider network.
Claim 9
Dependent Claim
21 words
The proximity sensor of Claim 7, wherein the detector means is energized by the voltage pulse produced by said pulse means.
Claim 10
Dependent Claim
22 words
The proximity sensor of Claim 7, further including a battery, said battery being the sole source of power for said proximity sensor.
Claim 11
Dependent Claim
20 words
The proximity sensor of Claim 7, wherein the target status signal produced by said detector means L an optical signal.
Claim 12
Dependent Claim
20 words
The proximity sensor of Claim 7, wherein the target status signal produced by said detector means is an AC signal.
Claim 13
Dependent Claim
20 words
The proximity sensor of Claim 7, wherein the target status signal produced by said detector means is a DC signal.
Claim 14
Dependent Claim
56 words
A proximity-sensing element comprising a reference coil and a sense coil connected in series between an input terminal and ground to receive a voltage signal, said coils having characteristic inductances that are related in a predetermined manner, the inductance of said sense coil being variable in a predetermined manner with the proximity of a target object.
Claim 15
Dependent Claim
56 words
A proximity-sensing element comprising a reference coil and a sense coil connected in series between an input terminal and ground to receive a voltage signal, said coils having characteristic inductances that are related in a predetermined manner, the inductance of said sense coil being variable in a predetermined manner with the proximity of a target object.
Claim 16
Dependent Claim
14 words
The proximity-sensing element of Claim 13, wherein said coils have substantially equal characteristic inductances.
Claim 17
Dependent Claim
45 words
The proximity-sensing element of Claim 14, wherein said coils are disposed relative to one another so that the inductance of said reference coil remains substantially constant and the inductance of said sense coil varies in a predetermined manner with the proximity of a target object.
Claim 18
Dependent Claim
52 words
The proximity-sensing element of Claim 15, wherein said sense coil and said reference coil are wound upon a core and arranged and connected such that, when a given external magnetic field induces current in each of said coils, the current induced in said sense coil cancels the current in said reference coil.
Claim 19
Independent Claim
66 words
A method for sensing proximity of a target object to a sensor inductor, comprising the steps of: connecting said sensor inductor in series with a reference inductor to form an inductive divider network; applying a voltage signal to said inductive divider network; and, detecting the resultant voltage across said sensor inductor to provide an indication of the proximity of the target object to said sensor inductor.
Claim 20
Independent Claim
66 words
A method for sensing proximity of a target object to a sensor inductor, comprising the steps of: connecting said sensor inductor in series with a reference inductor to form an inductive divider network; applying a voltage signal to said inductive divider network; and, detecting the resultant voltage across said sensor inductor to provide an indication of the proximity of the target object to said sensor inductor.
Claim 21
Dependent Claim
20 words
The method of Claim 17, wherein said step of applying comprises applying a voltage pulse to said inductive divider network.
Claim 22
Dependent Claim
54 words
The method of Claim 18, wherein said step of applying comprises applying a voltage pulse to said inductive divider network during each one of a plurality of successive system periods, and wherein said step of detecting comprises detecting the resultant voltage across said sensor inductor in synchronism with the application of said voltage pulses.
Claim 23
Dependent Claim
28 words
The method of Claim 19, wherein said step of detecting includes providing an optical output signal indicative of the proximity of said target object to said sensor inductor.
References Cited (Backward Citations)
No citation records indexed.
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