Level
OwnerJingdong Zhanginventor
Life of this patent
Estimating the term…
Abstract
The present invention provides a level sensor, preferably a level switch, which in use is mounted at the position at which a fluid level is to be monitored and uses a relatively low resolution TDR circuit to discriminate only between wet and dry states.
Claims19
A method of determining when an interface between a first fluid of a first permittivity and a second fluid of a second permittivity is at a defined level, said method comprising:
- providing an electromagnetic transmission line having an outer end;
- causing an electromagnetic pulse to be propagated along and reflected back along said transmission line by a time domain reflectometry (TDR) technique;
- and detecting an interval between an initial time reference and the time of receipt of a reflected pulse, said method being characterized in that in includes:
- mounting said transmission line at said defined level;
- and
- assessing only whether said transmission line is in said first fluid or said second fluid from an observation of a time interval between said initial time reference and receipt of a pulse reflected from said outer end.
A level sensor operable to determine when the interface between a first fluid of a first permittivity and a second fluid of a second permittivity is at a defined level, said sensor including an electromagnetic transmission line having an outer end;
- an electromagnetic pulse generator operable to cause an electromagnetic pulse to be propagated along and reflected back along said transmission line by a time domain reflectometry (TDR) technique;
- and a detection facility operable to detect a time interval between an initial time reference and the time of receipt of a reflected pulse, said sensor being characterized in that:
- in use, said transmission line is mounted at said defined level;
- and
- said detection facility is operable to assess only whether said transmission line is in said first fluid or in said second fluid from an observation of a time interval between said initial time reference and receipt of a pulse reflected from said outer end.
Dependencies are inferred from the claim text.