Electronic device for monitoring the temperature of a medium to be monitored and method for implementing the same

• US 20020180406A1
• Filed: 05/28/2002
• Published: 12/05/2002
• Est. Priority Date: 05/29/2001
• Status: Active Grant

• Current Assignee: EM Microelectronic - Marin SA (The Swatch Group AG)
• Original Assignee: EM Microelectronic - Marin SA (The Swatch Group AG)
• Inventors: Lamothe, Christian
• Granted Patent: US 6,798,219 B2
• Time in Patent Office: Days
• US Class Current: 320/150
• CPC Class Codes: G01K 3/005 Circuits arrangements for indicating a predetermined temperature fire detection G08B17/00
• CPC Class Codes: G06K 19/0717 the sensor being capable of sensing environmental conditions such as temperature history or pressure

Abstract

The present invention concerns an electronic device for monitoring the temperature of a medium to be monitored enabling one to make sure that the temperature has not reached at least a pre-established index limit value, characterised in that it includes:

contact means able to close an electric charge flow circuit when said temperature reaches the or one of the index limit values;

electric charge storage means able to be connected to the charge flow circuit when the contact means close, the charges stored in these storage means being kept as long as the temperature does not reach its or one of its index limit values, and being able to flow through said charge flow circuit when the circuit is closed by said contact means, said storage means not returning to the charge state which they had before the charge flow circuit closed if the latter opens again, and

read means enabling the charge state of said storage means to be determined.

Claims

1. An electronic device for monitoring the temperature of a medium to be monitored enabling one to make sure that the temperature has not reached at least a pre-established index limit value, wherein it includes:

electrically conductive contact means able to close an electric charge flow circuit when said temperature reaches the or one of the index limit values;

electric charge storage means able to be connected to the charge flow circuit when the contact means close, the charges stored in these storage means being kept as long as the temperature does not reach its or one of its index limit values, and being able to flow through said charge flow circuit when the circuit is closed by said contact means, said storage means not returning to the charge state which they had before the charge flow circuit closed if the latter opens again, and

read means enabling the charge state of said storage means to be determined.

2. The electronic device according to claim 1, wherein the charge storage means include a floating gate separated from a semiconductor substrate by an electrically insulating layer, the floating gate having an electric contact point that is accessible from the exterior and that can be connected to an electric contact point of the charge flow circuit.

3. The electronic device according to claim 1, wherein, in order to be able to evaluate the impedance of the read means and thus to determined the charge state of the floating gate, an oscillator circuit is associated with the read means, a remote interrogation device being able to be coupled to said read means.

4. The electronic device according to claim 1, wherein the read means include a pn junction formed at least in part under the floating gate.

5. The electronic device according to claim 2, wherein the read means include a bipolar transistor formed at least in part under the floating gate.

6. The electronic device according to claim 3, wherein the read means include a bipolar transistor formed at least in part under the floating gate.

7. The electronic device according to claim 1, wherein it includes an MOS type transistor whose gate, which is electrically insulated, forms the storage means, and whose source and drain form the read means.

8. The electronic device according to claim 7, wherein it includes a depletion MOS type transistor.

9. The electronic device according to claim 1, wherein the storage and read means include a non-volatile semiconductor memory cell.

10. The electronic device according to claim 9, wherein the semiconductor memory cell is chosen from the group formed by FAMOS type cells, SIMOS type cells, EEPROM type cells and EPLD separate injector memory cells.

11. The electronic device according to claim 1, wherein the contact means are formed by a material that conducts electricity and having a precise solidification and melting temperature.

12. The electronic device according to claim 11, wherein the electrically conductive material is a mixture of an antifreeze liquid and water the proportions of which determine the solidification and melting temperature of the mixture.

13. The electronic device according to claim 12, wherein the antifreeze liquid is alcohol.

14. The electronic device according to claim 1, wherein the contact means are made of a metallic material capable of expanding or contracting as a function of temperature fluctuations.

15. The electronic device according to claim 14, wherein the metallic material is chosen from the group formed by aluminium, silver, copper, steel, iron, invar, nickel, gold, platinum, lead, silicon, tungsten and zinc.

16. The electronic device according to claim 14, wherein the contact means take the form of a rectilinear bar.

17. The electronic device according to claim 15, wherein the contact means take the form of a rectilinear bar.

18. The electronic device according to claim 14, wherein the contact means take the form of a bimetalic switch.

19. The electronic device according to claim 15, wherein the contact means take the form of a bimetalic switch.

20. The Electronic device according to claim 1, wherein it is associated with an electronic tag.

21. A method for implementing the electronic temperature monitoring device of claim 1, comprising the steps of:

writing data by injecting electric charges into the charge storage means;

placing the electronic device in the medium whose temperature evolution one wishes to monitor in order to ensure that this temperature has not reached at least one pre-established index limit value;

reading, in a non destructive manner, while the device is still in the medium to be monitored, the data written in the charge storage means, so as to determine whether or not the temperature of said medium to be monitored has, at a given moment, reached its or one of its pre-established index limit values, knowing that if the temperature has not reached its or one of its index limit values, the contact means are not closed and the charge state of the charge storage means has remained unchanged, whereas if the temperature has reached its or one of its index limit values, the contact means have closed and the charge state of the charge storage means has been modified, this modified charge state of the charge storage means being preserved even if the temperature of the medium being monitored again passes below or beyond the index value which it has reached and the contact means open again;

continuing or stopping temperature monitoring and, if necessary,

reprogramming the electronic temperature monitoring device in order to use it again.

22. The method according to claim 21, wherein the step of writing data by injecting electric charges into the charge storage means occurs while the contact means are closed.

23. The method according to claim 21, wherein the step of writing data by injecting electric charges into the charge storage means occurs while the contact means are open.

24. The method according to claim 21, wherein the step of reading data written in the electric charge storage means is achieved by applying an electric current or voltage across the terminals of said charge storage means which, in response, provide a voltage, or respectively a current allowing the electric resistance of said storage means, and thus their electric charge state, to be determined.

25. The electronic device according to claim 2, wherein, in order to be able to evaluate the impedance of the read means and thus to determined the charge state of the floating gate, an oscillator circuit is associated with the read means, a remote interrogation device being able to be coupled to said read means.

26. The electronic device according to claim 2, wherein the read means include a pn junction formed at least in part under the floating gate.

27. The electronic device according to claim 3, wherein the read means include a pn junction formed at least in part under the floating gate.

28. The electronic device according to claim 2, wherein the storage and read means include a non-volatile semiconductor memory cell.

29. The method according to claim 22, wherein the step of reading data written in the electric charge storage means is achieved by applying an electric current or voltage across the terminals of said charge storage means which, in response, provide a voltage, or respectively a current allowing the electric resistance of said storage means, and thus their electric charge state, to be determined.

30. The method according to claim 23, wherein the step of reading data written in the electric charge storage means is achieved by applying an electric current or voltage across the terminals of said charge storage means which, in response, provide a voltage, or respectively a current allowing the electric resistance of said storage means, and thus their electric charge state, to be determined.