Optically powered sensor system

• US 4,820,916 A
• Filed: 05/05/1987
• Issued: 04/11/1989
• Est. Priority Date: 05/05/1987
• Status: Expired due to Term

• Current Assignee: Simmonds Precision Products, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Original Assignee: Simmonds Precision Products, Inc. (Raytheon Technologies Corporation d/b/a RTX)
• Inventors: Patriquin, Douglas R.
• Primary Examiner(s): Nelms, David C.
• Assistant Examiner(s): Messinger, Michael
• Application Number:
  US07/046,075
• Time in Patent Office: 707 Days
• Field of Search: 250/231 R, 250/231 P, 250/227, 250/551, 350/96.15, 350/96.16, 350/96.17, 455/602, 455/605, 455/606, 455/607, 455/608, 455/610, 455/612, 455/617, 455/613
• US Class Current: 250/208.2
• CPC Class Codes: H04B 10/807 Optical power feeding, i.e. transmitting power using an optical signal

Abstract

An optically powered sensor system includes a plurality of sensors connected to a system optical bus that communicates with a system controller. Optical energy is transmitted along the bus for distribution to all sensors in the system with return pulses from the various sensors transmitted on the bus to the system controller. Each sensor includes a photodiode array for converting optical energy transmitted system-wide by the controller into electrical energy for storage in a storage capacitor associated with each sensor. A transducer, such as a thermistor, and a fixed-value reference, such as a resistor, are connected to a pulse encoder and, in response to power switched from the capacitor, the pulse encoder produces a series of short-duration pulses having a pulse spacing that is dependent upon the fixed value of the reference and the parameter-affected value of the transducer. The pulses are used to drive an optical source for transmitting optical pulses from the sensor to the system controller. The parameter value is determined by multiplying the known value of the reference resistor by a time factor ratio which is related by the reference pulse timing and the parameter-affected pulse timing. An optical sensor system is provided in which the measurement of a parameter by each sensor is immune to variations in the electrical components at each sensor.

Claims

1. An optically powered sensor system comprising:

an optical energy source for transmitting optical energy;

an optical pathway for conveying the optical energy transmitted by said optical energy source;

at least one sensor connected to said optical pathway for receiving optical energy from said optical energy source, said sensor including means for converting optical energy from said optical pathway to electricity and storing the electrical energy, a transducer responsive to a selected parameter and having an electrical characteristic that varies as a function of the selected parameter, a reference component having an electrical characteristic that is independent of the selected parameter, circuit means for providing electrical energy from said converting and storing means to said transducer and said reference component and producing a multi-pulse output having a first time attribute that is a function of the electrical characteristic of said transducer and a second time attribute that is a function of the electrical characteristic of said reference component.

2. The optically powered sensor system of claim 1, further comprising:

means for converting the pulse output of said circuit means to an optical pulse output.

3. The optically powered sensor system of claim 1, further comprising:

means for converting the pulse output of said circuit means to an optical pulse output and for introducing the optical pulse output onto said optical pathway.

4. The optically powered sensor system of claim 1, wherein said transducer comprises a temperature-responsive resistor and said reference component comprises a fixed-value resistor.

5. The optically powered sensor system of claim 1, wherein said circuit means produces at least a first set of two pulses, the interpulse spacing of which is a function of the electrical characteristic of said transducer, and another set of pulses, the interpulse spacing of which is a function of the electrical characteristic of said reference component.

6. The optically powered sensor system of claim 5, wherein the pulses of said first and second sets of pulses are fixed-duration pulses.

7. The optically powered sensor system of claim 1, wherein said circuit means further comprises a first pulse generator for generating pulses having pulse widths that are a function of the transducer electrical characteristic and of the reference component electrical characteristic and a second pulse generator connected to said first pulse generator for providing fixed-duration pulses in response to the leading and trailing edge transitions of said pulse-width modulated pulses.

8. The optically powered sensor system of claim 7, wherein said circuit means further comprises:

means for selectively switching electricity from said converting and storing means between said transducer and said reference component.

9. The optically powered sensor system of claim 8, wherein said circuit means further comprises:

a bi-state latch between said first and second pulse generators, said latch changing state with the leading and trailing edge transitions of the pulse-width modulated pulses to trigger said second pulse generator.

10. An optically powered sensor for sensing a parameter and providing a pulse output representative of the sensed parameter, comprising:

means for converting optical energy to electricity and storing the electrical energy, a transducer responsive to a selected parameter and having an electrical characteristic that varies as a function of the selected parameter, a reference component having an electrical characteristic that is independent of the selected parameter, circuit means for providing electrical energy from said converting and storing means to said transducer and said reference component and producing a multi-pulse output having a first time attribute that is a function of the electrical characteristic of said transducer and a second time attribute that is a function of the electrical characteristic of said reference component.

11. The optically powered sensor of claim 10, wherein said circuit means produces at least a first set of two pulses, the interpulse spacing of which is a function of the electrical characteristic of said transducer, and another set of pulses, the interpulse spacing of which is a function of the electrical characteristic of the reference component.

12. The optically powered sensor of claim 11, wherein the pulses of said first and second sets of pulses are fixed-duration pulses.

13. The optically powered sensor of claim 10, wherein said circuit means further comprises a first pulse generator for generating successive pulses having respective pulse widths that are a function of the parameter-affected electrical characteristic of the transducer and of the electrical characteristic of the reference component and a second pulse generator connected to said first pulse generator for providing fixed-duration pulses in response to the leading and trailing edge transitions of said pulse-width modulated pulses.

14. The optically powered sensor of claim 13, wherein said circuit means further comprises:

means for selectively switching electricity from said converting and storing means between said transducer and said reference component.

15. The optically powered sensor of claim 14, wherein said circuit means further comprises:

a bi-state latch between said first and second pulse generators, said latch changing state with the leading and trailing edge transitions of the pulse-width modulated pulses to trigger said second pulse generator.

16. The optically powered sensor of claim 10, further comprising:

means for converting the pulse output of said circuit means to an optical pulse output.

17. The optically powered sensor of claim 10, wherein said transducer comprises a temperature responsive resistor and said reference component comprises a fixed-value resistor.