Current measuring apparatus using light-emitting devices

• US 4,378,496 A
• Filed: 10/22/1980
• Issued: 03/29/1983
• Est. Priority Date: 10/29/1979
• Status: Expired due to Term

• Current Assignee: Asea Aktiebolag (ABB Limited)
• Original Assignee: Asea Aktiebolag (ABB Limited)
• Inventors: Brogardh, Torgny, Ovren, Christer, Engstrom, Olof, Sander, Lars
• Primary Examiner(s): Nelms, David C.
• Assistant Examiner(s): Hostetter, Darwin R.
• Application Number:
  US06/199,446
• Time in Patent Office: 888 Days
• Field of Search: 250/227, 250/231 R
• US Class Current: 250/227.23
• CPC Class Codes: G01R 15/22 using light-emitting devices, e.g. LED, optocouplers G01R31/31901 takes precedence

Abstract

The invention relates to a device for measuring current which traverses a light-emitting structure, the current passage thus causing emission of light. It is characterized in that the emitted light signal is adapted to be supplied to two photo-detectors having different sensitivity spectra and/or with at least one photo-detector being provided with an optical filter. The output signals of the photo-detectors are adapted to be supplied to a quotient forming member and/or a calculating member for obtaining a signal which is compensated for temperature variations in the light-emitting structure and other sources of error.

Claims

1. A device for measuring current comprising:

electroluminescence means for generating light within first and second dissimilar wavelength intervals in response to stimulation by said current such that said electroluminescence means is modulated by said current;

said electroluminescence means further comprising a material compositionally formed and dimensioned such that said light exhibits a plurality of non-uniform current dependencies;

at least one optical fiber optically connected to said electroluminescence means;

first and second photo-detectors each optically connected to said at least one optical fiber and respectively having first and second sensitivity spectra and respectively adjusted to said first and second wavelength intervals such that said first photo-detector selectively senses said light in at least a portion of said first wavelength interval and said second photo-detector senses said light in at least a portion of said second wavelength interval.

2. A device as claimed in claim 1 wherein said electroluminescence means further comprises at least one diode.

3. A device as claimed in claim 1 wherein said material further comprises a doped semiconductor material including a plurality of light emitting structures containing a doping material, said doped semiconductor material having band to band junctions and having charge carriers injected therein by said current so as to recombine said charge carriers via said band to band junctions and via said light emitting structures.

4. A device as claimed in claim 1 wherein said electroluminescence means further comprises first and second material junctions electrically connected in series with said current, said first material junction having a first material composition and said second material junction having a second material composition different from said first material composition so as to generate dissimilar electroluminescent spectra within said first and second dissimilar wavelength intervals.

5. A device as claimed in claim 4 wherein said first and second material junctions further comprise pn junctions.

6. A device as claimed in claim 4 wherein said first and second material junctions further comprise Schottky junctions.

7. A device as claimed in claim 4 wherein said first material composition comprises first doping means and said second material composition comprises second doping means different from said first doping means so as to generate said dissimilar electroluminescent spectra.

8. A device as claimed in claim 16 wherein said first and second material junctions further comprise metal insulator semiconductor junctions.

9. A device as claimed in claim 4, 5, 6 or 7 wherein said material further comprises a plurality of charge carriers injected in said first and second material junctions by said current and recombining in said material.

10. A device as claimed in claim 1 wherein said material further comprises an undoped material.

11. A device as claimed in claim 9 wherein said material further comprises (Zn, O) doped material.

12. A device as claimed in claim 9 wherein said material further comprises (Cd, O) doped material.

13. A device as claimed in claim 9 wherein said material further comprises doped GaP material.

14. A device as claimed in claim 1 wherein said plurality of non-uniform current dependencies further comprises band to band type recombination current dependencies.

15. A device as claimed in claim 1 wherein said plurality of non-uniform current dependencies further comprises impurity type recombination current dependencies.

16. A device as claimed in claims 14 or 15 wherein said material further comprises GaAs.

17. A device as claimed in claim 13 further comprising:

means for dividing an output of said first photo-detector by an output of said second photo-detector and for producing a corresponding divided output; and

means for generating an output signal representative of said current from said divided output of said means for dividing wherein said output signal is compensated for intensity variations unrelated to said current in said light generated by said electroluminescence means.

18. A current measuring device, comprising:

means for generating light in response to stimulus by the current to be measured and being modulated thereby;

at least two photo-detectors for detecting the light generated by said generating means, said at least two photo-detectors having different spectral sensitivity characteristics with respect to the wavelength of said light wherein at least one of said at least two photo-detectors optically contacts a photo-luminescence material;

at least one optical fiber for transmitting said light from said generating means to said at least two photo-detectors;

an optical filter for filtering the light transmitted to at least one of said at least two photo-detectors;

means for generating a reference light signal;

means for modulating said reference light generating signal at a frequency different than the modulation frequency of the light generated by said generating means, said at least one optical fiber transmitting the modulated reference signal to said means for generating light;

means for dividing the output of one of said at least two photo-detectors by the output of another of said at least two photo-detectors; and

means for generating an output signal representative of the current to be measured from the output of said means for dividing, said output signal being compensated for intensity variations unrelated to said current in said light generated by said generating means.

19. A current measuring device, comprising:

means for generating light in response to stimulus by the current to be measured being modulated thereby;

at least two photo-detectors for detecting the light generated by said generating means, said at least two photo-detectors having different spectral sensitivity characteristics with respect to the wavelength of said light, wherein at least one of said at least two photo-detectors is in optical contact with a photo-luminescent material and includes two pn junctions made of material with different band gaps such that the emitted light signal traverses said two pn junctions;

at least one optical fiber for transmitting said light from said generating means to said at least two photo-detectors;

an optical filter for filtering the light transmitted to at least one of said at least two photo-detectors;

means for generating a reference light signal;

means for modulating said reference light generating signal at a frequency different than the modulation frequency of the light generated by said generating means, said at least one optical fiber transmitting the modulated reference signal to said means for generating light;

means for dividing the output of one of said at least two photo-detectors by the output of another of said at least two photo-detectors; and

means for generating an output signal representative of the current to be measured from the output of said means for dividing, said output signal being compensated for intensity variations unrelated to said current in said light generated by said generating means.

20. A current measuring device as in claim 19, wherein said means for generating light is a semiconductor diode.

21. A current measuring device as in claim 19, wherein said means for generating light is a semiconductor laser.

22. A current measuring device as in claim 19, wherein said means for generating light is a Schottky diode.

23. A current measuring device as in claim 19, wherein said means for generating light is a metal insulator semiconductor.

24. A current measuring device as in claim 19, wherein said means for generating light consists of two light emitting elements connected in series with one another.

25. A current measuring device as in claim 19, wherein said means for generating light is two light emitting elements connected in anti-parallel relationship and including a current transformer connected to the current to be measured.

26. A current measuring device as in claim 19, wherein said means for generating light is a semiconductor crystal doped such that two opposed sides have intersecting surfaces with both n type and p type conducting materials.

27. A current measuring device as in claim 25, wherein said reference light signal is transmitted to at least one of said at least two photo-detectors and the output signal thereof is input to said means for dividing.

28. A current measuring device as in claim 19 further comprising means for regulating the current and temperature of said means for generating a reference light signal.