Method and system to transmit signals being generated by a measuring sensor, and specifically a temperature sensor

• US 4,848,923 A
• Filed: 09/29/1987
• Issued: 07/18/1989
• Est. Priority Date: 10/04/1986
• Status: Expired due to Fees

• Current Assignee: Heraeus Holding GMBH
• Original Assignee: WC Heraeus GmbH (Heraeus Holding GMBH)
• Inventors: Hauptmann, Veit, Brendecke, Hermann, Ziegler, Horst
• Primary Examiner(s): YASICH, DANIEL
• Application Number:
  US07/102,111
• Time in Patent Office: 658 Days
• Field of Search: 374/117, 374/102, 331/66, 310/68 C, 340/870.17
• US Class Current: 374/117
• CPC Class Codes: G01D 18/00 Testing or calibrating apparatus or arrangements provided for in groups G01D1/00 - G01D15/00

Abstract

Temperature measurement is effectively carried out by converting pulses derived from a pulse generator, in which the pulse gaps change as a result of a measured condition, for example temperature, by converting electrical pulses received from the pulse generator into light pulses, and then evaluating the light pulses with respect to a clock rate in a counter (22). The light pulses can readily be transmitted via a light pickup (9b) and fiber optic or the like (9a) to a remote evaluation unit. Preferably, the light is generated by a light emitting diode or a laser diode (8'"'"'), serially connected with a switching transistor (13'"'"') and energized upon receipt of a pulse from the pulse generator. The arrangement permits use of a piezoelectric element (2) such as a frequency determining quartz to control the frequency of an oscillator, the frequency of which is then converted into the pulses with the respective pulse gaps.

Claims

1. A method of wirelessly transmitting and reading out signals which are being generated in the form of electrical signals by a remote measuring sensor, especially a temperature sensor, comprising the steps of

subjecting a quartz crystal (2) to a physical parameter;

coupling said quartz crystal to an oscillator (3) and generating (5) electrical signals as a sequence of pulses in which gaps between pulses represent a specific measured value of said parameter, especially temperature level;

providing a time base (20);

converting the electrical signals into light impulses;

detecting (21) and evaluating (22), at a location remote from said crystal (2) and oscillator (3), the light impulses with respect to said time base, and

indicating or reading out results of said evaluating step.

2. The method of claim 1, wherein the step of evaluating the light impulses with respect to said time base comprises

reconverting the light impulses into electrical signals;

and evaluating the electrical signals with respect to clock pulses.

3. The method of claim 2, including the step of transmitting said light pulses after conversion thereinto over a distance prior to reconverting the light pulses into electrical signals.

4. The method of claim 1, wherein said pulse-generating step comprises changing the duration of said gap between pulses by up to 10% of a maximum value thereof, over a predetermined maximum range of said physical parameter.

5. System for sensing and evaluating a measurable condition or parameter including

an oscillator (3);

a quartz measuring transducer (2) coupled to the oscillator (3) and converting the frequency received therefrom to a sequence of pulses in which the time duration of pulse gaps is representative of said frequency and hence of the measured condition;

a light generator (8, 8'"'"') coupled to and controlled by the pulse generator and providing light flashes or pulses, the spacing of which is representative of the frequency of oscillations of the oscillator and hence of the measured condition;

means (9b) for detecting said light pulses and converting them to electrical signals; and

means (20a), coupled to said detecting means, for evaluating said electrical signals and indicating values of the measured condition.

6. System according to claim 5, further comprising a frequency divider (4) coupled between the oscillator (3) and the pulse generator (5).

7. System according to claim 6, wherein the frequency divider has a controllable frequency ratio;

and a control switching circuit (7) controlling the division factor of the frequency divider to permit correction of tolerances of the measuring transducer.

8. System according to claim 5, wherein the measuring transducer (2) comprises a piezoelectric element.

9. System according to claim 8, wherein the measuring transducer (2) comprises a frequency determining quartz element.

10. System according to claim 5, further including an electronic switch (13) having a control terminal (12) connected to the output (6) of the pulse generator;

and a light generator (8) connected serially in the main current path (14,

     15) of the electronic switch (13).

11. System according to claim 10, wherein the light generator (8) is a light emitting diode (LED) (8'"'"').

12. System according to claim 10, wherein the light generator (8) comprises a laser diode.

13. System according to claim 10, wherein the light generator emits humanly perceptible visible light.

14. System according to claim 5, wherein the light generator (8) emits infrared light.

15. System according to claim 5, further including an optical-to-electrical signal transducer (21) optically responsible to the light emitted by the light generator (8,8'"'"') and optically coupled thereto.

16. System according to claim 15, further including a light pickup (9b), and a light guide, or fiber optic (9a), the light pickup (9b) being optically coupled to the light generator and the light guide or fiber optic being optically coupled to the optical-electrical transducer (21).

17. System according to claim 15, further including a counter (22) receiving light pulses from the optical-electrical transducer, and comparing the gaps between said pulses with a counter clock.

18. System according to claim 16, further including a counter (22) receiving light pulses from the optical-electrical transducer, and comparing the gaps between said pulses with a counter clock.

19. System according to claim 16, wherein the time duration of the pulse gaps, changing as a result of change in said measured condition or parameter, is in the order of about 10% of the time duration between gaps.

20. System according to claim 17, further including a counter (22) receiving light pulses from the optical-electrical transducer, and comparing the gaps between said pulses with a counter clock.