Meter sensor light tamper detector

• US 5,750,983 A
• Filed: 01/06/1997
• Issued: 05/12/1998
• Est. Priority Date: 03/20/1995
• Status: Expired due to Fees

• Current Assignee: Itron, Inc.
• Original Assignee: Schlumberger Industries Incorporated (SLB)
• Inventors: Swanson, Scott C.
• Primary Examiner(s): Allen, Stephone B.
• Application Number:
  US08/779,330
• Time in Patent Office: 491 Days
• Field of Search: 250/231.13, 250/221, 250/222.1, 324/110
• US Class Current: 250/231.13
• CPC Class Codes: G01D 4/008 Modifications to installed utility meters to enable remote reading
• CPC Class Codes: G01D 5/34715 Scale reading or illumination devices
• CPC Class Codes: G01R 11/24 Arrangements for avoiding or indicating fraudulent use
• CPC Class Codes: Y02B 90/20 Smart grids as enabling technology in buildings sector smart grids supporting the management or operation of end-user stationary applications in general, or like technologies with no associated climate change mitigation effect Y04S20/00
• CPC Class Codes: Y04S 20/30 Smart metering, e.g. specially adapted for remote reading

Abstract

A meter sensor light tamper detector includes at least one light emitter and one or more sensors. The sensors have some parameter, i.e., conductivity in the case of phototransistor sensors, to provide an indication that they are in the presence of light. The system also includes a microprocessor which is capable of independent control of the light emitter and the sensors, and can determine the state of the electrical parameter, i.e., conductivity or nonconductivity, of the sensors. The microprocessor determines whether the sensors are being tampered with by checking the state of the sensors when a particular light condition is known to be present or absent.

Claims

1. A meter sensor light tamper detector, comprising:

a first and a second light sensor, each being in a first operating state in the presence of an amount of light and in a second operating state in the absence of said amount of light;

a first light emitter operable to illuminate at least said first light sensor with said amount of light; and

a microprocessor determining said first and second operating states of said first and said second sensors and controlling emission of said first light emitter, wherein said microprocessor recognizes said meter sensor is subject to tampering whenever it determines said first and second light sensors are both in said first operating state at a time when said first light emitter is emitting said amount of light.

2. The tamper detector of claim 1 further comprising a second light emitter operable to illuminate at least said second light sensor with said amount of light and controlled by said microprocessor to emit said amount of light concurrently with said first light emitter.

3. The tamper detector of claim 1 further comprising a meter disk, said meter disk disposed proximate to said first light emitter.

4. The tamper detector of claim 3 wherein said first light emitter is positioned to reflect light off a surface of said meter disk and wherein said first and second light sensors are positioned to detect the reflection of said light off said surface.

5. The tamper detector of claim 3 wherein said meter disk has a plurality of light absorbing areas.

6. The tamper detector of claim 3 wherein said meter disk has a plurality of apertures.

7. The tamper detector of claim 6 wherein said first light emitter is positioned to create a light path through at least one of said plurality of apertures and wherein one of said first and second light sensors is positioned in said light path when said meter disk is in a specific rotational position.

8. The tamper detector of claim 1 wherein said microprocessor sets an alarm condition whenever said first light sensor and said second light sensor are both in said first operating state.

9. The tamper detector of claim 1 wherein said microprocessor notifies a monitor whenever said first light sensor and said second light sensor are both in said first operating state.

10. The tamper detector of claim 1 wherein said first operating state is an electrically conductive state and said second operating state is an electrically nonconductive state.

11. A method for detecting tampering of a meter sensor, including a first light emitter and a first and a second light sensor, for use with a meter including a rotor shaft having a disk affixed thereto, said disk having at least a first opening positioned to pass light from said first light emitter to said first light sensor when the disk is in a first position, the method comprising the steps of:

causing said first light emitters to became conductive;

checking at substantially the same time whether said first light sensor and said second light sensor are in a particular operating state while said first light emitter is conductive; and

establishing that said meter sensor is subject to tampering whenever said step of checking indicates that both said first light sensor and said second light sensor are in said particular operating state.

12. The method of claim 11 further comprising the step of notifying a monitor that tampering is occurring.

13. The method of claim 11 wherein said particular operating state is an electrically conductive state.

14. The method of claim 13 wherein said meter sensor includes a second light emitter, and said step of causing said first light emitter to become conductive further includes the step of causing said second light emitter to become conductive at substantially the same time, and wherein said second light emitter is also conductive during said step of checking said first and second light sensors.

15. The method of claim 14 wherein said disk includes a second opening positioned to pass light from said second light emitter to said second light sensor when said disk is in a second position, said first opening and said second opening being arranged such that light cannot simultaneously be received by both said first light sensor and said second light sensor from said first light emitter and second light emitter, respectively.

16. A method for detecting tampering of a meter sensor, the method comprising the steps of:

turning on a first light emitter;

checking whether a first light sensor is conductive or noncondutive while said first light emitter is on, said first light emitter selectively conveying light to said first light sensor;

checking a second light sensor to determine whether said second light sensor is conductive or nonconductive at the same time as said first light sensor; and

establishing that said meter sensor is subject to tampering whenever said steps of checking indicate that both said first light sensor and said second light sensor are conductive.

17. The method of claim 16 further comprising the steps of turning on a second light emitter and keeping said second light emitter on during said steps of checking said first and second light sensors, said second light emitter selectively conveying light to said second light sensor.

18. A system for detecting tampering of a meter sensor for use with a meter including a rotor shaft, the system comprising:

a first light emitter and a second light emitter;

a first light sensor and a second light sensor disposed proximate to said first light emitter and said second light emitter, respectively;

a disk affixed to the rotor shaft, said disk having a first opening positioned to pass light from said first light emitter to said first light sensor when said disk is in a first position, and a second opening position to pass light from said second light emitter to said second light sensor when said disk is in a second position, said first and second openings being arranged such that light cannot simultaneously be received by both said first light sensor and said second light sensor from said first light emitter and said second light emitter, respectively;

a microprocessor having a first input for receiving a first signal indicative of the conductivity or nonconductivity of said first light sensor;

said microprocessor further having a second input for receiving a second signal indicative of the conductivity or nonconductivity of a second light sensor;

wherein said microprocessor determines that said meter sensor is being tampered with by receiving signals indicating that both said first and second light sensors are conductive at the same time while said first and second light emitters are asserted.

19. A system for detecting tampering of a meter sensor for use with a meter including a rotor shaft, the system comprising:

a light emitter;

a first light sensor and a second light sensor disposed proximate to said first light emitter;

a disk affixed to the rotor shaft, said disk having a first opening positioned to pass light from said light emitter to said first light sensor when said disk is in a first position, and a second opening positioned to pass light from said light emitter to said second light sensor when said disk is in a second position, said first opening and said second opening being arranged such that light from said emitter cannot simultaneously be received by both said first light sensor and said second light sensor;

a microprocessor having a first input for receiving a signal indicative of the conductivity or nonconductivity of said first light sensor, and a second input for receiving a signal indicative of the conductivity or nonconductivity of said second light sensor;

wherein said microprocessor determines that said meter sensor is being tampered with by the receipt at about the same time of both a signal indicative of the conductivity of said first light sensor and a signal indicative of the conductivity of said second light sensor while said emitter is asserted.