Apparatus and methods for proximity sensing circuitry
First Claim
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1. An inductive proximity sensor comprising:
- a source circuit containing only a current source, a switch, and an inductive source element, wherein the source circuit is a circuit loop containing only the switch which is coupled to the current source and the inductive source element which is coupled to the switch at a connection point, and wherein the switch is configured to operatively couple the current source to the inductive source element in a first state and to operatively isolate the current source from the inductive source element in a second state; and
a resonant circuit comprising a target sensing inductive element and a reference inductive element directly coupled together at a node, and a capacitive element having a first side directly connected to the node and a second side directly connected to the connection point,wherein the source circuit is configured to energize the resonant circuit via the capacitive element, andwherein the target sensing inductive element is oriented in a substantially orthogonal direction relative to the reference inductive element.
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Abstract
An inductive proximity sensor is disclosed. The proximity sensor includes a source circuit with an inductive element configured to deliver energy to a resonator when a source current is changed. In various embodiments, the source current is provided a step current source. In various embodiments, the source current is provided by constant current source coupled to the inductive element by a switch. Apparatus and methods for operating the inductive proximity sensor are disclosed.
16 Citations
19 Claims
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1. An inductive proximity sensor comprising:
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a source circuit containing only a current source, a switch, and an inductive source element, wherein the source circuit is a circuit loop containing only the switch which is coupled to the current source and the inductive source element which is coupled to the switch at a connection point, and wherein the switch is configured to operatively couple the current source to the inductive source element in a first state and to operatively isolate the current source from the inductive source element in a second state; and a resonant circuit comprising a target sensing inductive element and a reference inductive element directly coupled together at a node, and a capacitive element having a first side directly connected to the node and a second side directly connected to the connection point, wherein the source circuit is configured to energize the resonant circuit via the capacitive element, and wherein the target sensing inductive element is oriented in a substantially orthogonal direction relative to the reference inductive element. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A proximity detector, comprising:
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an inductive proximity sensor comprising a circuit loop containing only a current source, an inductive circuit element, and a control element configured to initiate a change in a current flowing in the inductive circuit element, the control element located in the circuit loop, and wherein the inductive circuit is coupled to the control element at a connection point; and the inductive proximity sensor further comprising a resonant circuit coupled to the inductive circuit element, the resonant circuit comprising a target sensing inductive element and a reference inductive element both directly connected to a first side of a capacitive element wherein a second side of the capacitive element is directly connected to the connection point, wherein the reference inductive element is oriented substantially orthogonally relative to the target sensing inductive element and wherein the current flowing in the inductive circuit element and a voltage across the resonant circuit are initially unchanged upon activating the control element. - View Dependent Claims (10, 11, 12, 13)
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14. A process control system, comprising:
- an inductive proximity sensor comprising a source current circuit containing only a current source, an inductive circuit element and a control component, the control component configured to initiate a change in a current flowing in the inductive circuit element, wherein the control component is coupled in the source current circuit, and wherein the inductive circuit element is coupled to the control component at a connection point;
the inductive proximity sensor further comprising a resonant circuit coupled to the inductive circuit element, the resonant circuit connected to the control component, the resonant circuit comprising a target sensing inductive element and a reference inductive element directly connected together at a node and oriented substantially orthogonally relative to one another, and a capacitive element having a first side directly connected to the node and a second side directly connected to the connection point, wherein the current flowing in the inductive circuit element and a voltage across the resonant circuit are initially unchanged upon activating the control component; and
a processor coupled to at least one of the source current circuit or the inductive proximity sensor, wherein the processor is configured to process signals associated with eddy currents generated in a metal based on an output of the inductive proximity sensor. - View Dependent Claims (15, 16, 17, 18, 19)
- an inductive proximity sensor comprising a source current circuit containing only a current source, an inductive circuit element and a control component, the control component configured to initiate a change in a current flowing in the inductive circuit element, wherein the control component is coupled in the source current circuit, and wherein the inductive circuit element is coupled to the control component at a connection point;
Specification