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US 2015/0084646 A1Published application
Low power inductive proximity sensing system
OwnerFred Mirowinventor
Life of this patent
Estimating the term…
Abstract
A low power inductive proximity sensing system in which a DC voltage to the inductors is only applied for a short time period needed to detect the presence or absence of an appropriate object. After the detection time period is over, DC voltage is no longer applied to the inductors.
Claims4
An inductive proximity detector comprising:
- a first and second inductor wherein the inductance value of one or both of said first and second inductor varies in response to proximity of an object to be sensed;
- first and second time delay comprising said first and second inductor;
- time constant of said first time delay responsive to the inductance value of said first inductor;
- time constant of said second time delay responsive to the inductance value of said second inductor;
- oscillator for controlling time at which DC voltage supply is connected to inputs of both first and second time delay;
- first voltage level detector output level responsive to said first time delay time constant;
- second voltage level detector output level responsive to said second time delay time constant;
- said first or second voltage level detector determining time at which said DC voltage supply is no longer connected to both said first and second time delay;
- an output signal determined by comparing said first time delay time constant to said second time delay time constant;
- and
- said oscillator having time period longer then time required for said first and second time delay output voltage level to reach a low voltage level after said DC voltage supply is no longer connected to both said first and second time delay.
8 more elements
An inductive proximity detector comprising:
- an inductor wherein the inductance value of said inductor varies in response to proximity of an object to be sensed;
- first time delay comprising said inductor;
- a second time delay circuit;
- time constant of said first time delay responsive to the inductance value of said first inductor;
- time constant of said second time delay is substantially constant;
- oscillator for controlling time at which DC voltage supply is connected to inputs of both first and second time delay;
- first voltage level detector output level responsive to said first time delay time constant;
- second voltage level detector output level responsive to said second time delay time constant;
- said first or second voltage level detector determining time at which said DC voltage supply is no longer connected to both said first and second time delay;
- an output signal determined by comparing said first time delay time constant to said second time delay time constant;
- and
- said oscillator having time period longer then time required for said first and second time delay output voltage level to reach a low voltage level after said DC voltage supply is no longer connected to both said first and second time delay.
9 more elements
Dependencies are inferred from the claim text.