Switch status sensor

• US 6,255,748 B1
• Filed: 12/01/1998
• Issued: 07/03/2001
• Est. Priority Date: 01/11/1996
• Status: Expired due to Fees

• Current Assignee: Fusion Meters Limited
• Original Assignee: Fusion Meters Limited
• Inventors: Allcorn, Roger
• Primary Examiner(s): FLEMING, FRITZ M
• Application Number:
  US09/101,691
• Time in Patent Office: 945 Days
• Field of Search: 307/112, 307/113, 307/116, 307/125, 307/126, 307/130, 307/131, 324/418, 324/419, 324/424, 324/500, 324/512, 324/522, 324/523, 361/78, 361/79, 361/86, 361/87, 361/139, 361/152, 361/154, 361/160, 361/170, 361/187-190, 340/644, 377/19, 377/21, 377/28-30, 377/55, 377/111
• US Class Current: 307/125
• CPC Class Codes: H01H 35/405 the switch being of the reed switch type
• CPC Class Codes: H01H 9/167 Circuits for remote indication

Abstract

A switch status sensor is provided for counting on/off events of a switch of a water meter. When an on/off event is detected by a microcontroller, the microcontroller supplies a “signature” signal, which is distinguishable from electromagnetic noise, to the switch. If this “signature” signal is detected as having passed through the switch by the microcontroller, then it can be confirmed that the switch is closed. Alternatively, if the “signature” signal is not detected as having passed through the switch by the microcontroller, then it is verified that the switch is open. Thus, the switch status sensor can distinguish between false switch events caused by electromagnetic noise and true on/off events of the switch.

Claims

1. A switch status sensor for connection to a switch, the switch status sensor comprising:

a current detector that is configured to provide an indicated status of the switch,

a signal generator that is configured to apply a signal to the switch, so that the signal passes through the switch when the switch is closed, and does not pass through the switch when the switch is open, and

a signal detector that is configured to detect a communication of the signal via the switch, and thereby determine a verified status of the switch, and

wherein

the signal generator applies the signal to the switch in response to the indicated status of the switch from the current detector.

2. A switch status sensor according to claim 1, wherein

the indicated status corresponds to the switch being opened.

3. A switch status sensor according to claim 1, wherein

the indicated status corresponds to the switch being closed.

4. A switch status sensor according to claim 1, further including

a filter, operably coupled to the switch and the current detector, that is configured to filter signals communicated between the switch and the current detector.

5. A switch status sensor according to claim 4, further including

a switch that is configured to selectively disable the filter.

6. A switch status sensor according to claim 1, further comprising:

a counter that is configured to contain a count of changes in the verified status of said switch, and

an interface that is configured to make the count available to external apparatus.

7. A switch status sensor according to claim 1, further comprising

a current controller that is configured to control current applied to the switch to reduce power consumption by the switch status sensor.

8. A switch status sensor according to claim 1, wherein

at least one of:

the current detector, the signal generator, and the signal detector are embodied in a microprocessor.

9. A water meter for measuring a flow of water comprising:

a switch that is configured to change state in dependence upon the flow of water, and

a switch status sensor comprising;

a current detector that is configured to provide an indicated state of the switch,

a signal generator that is configured to apply a signal to the switch, so that the signal passes through the switch when the switch is closed, and does not pass through the switch when the switch is open, and

a signal detector that is configured to detect a communication of the signal via the switch, and thereby determine a verified state of the switch, and

wherein

the signal generator applies the signal to the switch in response to the indicated state of the switch from the current detector.

10. A switch status sensor circuit adapted for connection to an electrical switch, comprising:

a current detector responsive to an electrical current flowing through a connection from the switch to the current detector, to determine changes in status of the switch and

a signal generator responsive to the status of the switch, for supplying a signal to the switch, so that the signal passes through the switch when the switch is closed, and does not pass through the switch when the switch is open, and

a switch status verifier that is configured to sense communication of the signal through the switch, to test whether the status that is determined by the current detector is correct.

11. A switch status sensor according to claim 10, wherein

the status of the switch corresponds to the switch being opened.

12. A switch status sensor according to claim 10, wherein

the status of the switch corresponds to the switch being closed.

13. A switch status sensor according to claim 10, wherein

a filter is provided for filtering the electrical current flowing through the connection from the switch.

14. A switch status sensor according to claim 13, wherein

said filter is configured to be selectively disabled during detection of said electrical current.

15. A switch status sensor according to claim 10, further comprising:

a counter that is configured to accumulate a count that corresponds to changes in the status of the switch, and

an interface that is configured to make the count available to external apparatus.

16. A switch status sensor according to claim 10, further comprising

a current controller that is configured to control the electrical current applied to the switch, to reduce power consumption by the switch status sensor.

17. A water meter for measuring a flow of water comprising:

a switch that is configured to change state in dependence upon the flow of water, and

a switch status sensor comprising;

a current detector responsive to an electrical current flowing through a connection from the switch to the current detector, to determine changes in status of the switch and

a signal generator responsive to the status of the switch, for supplying a signal to the switch, so that the signal passes through the switch when the switch is closed, and does not pass through the switch when the switch is open, and

a switch status verifier that is configured to sense communication of the signal through the switch, to test whether the status that is determined by the current detector is correct.