DEVICE FOR MEASURING TWO PHYSICAL QUANTITIES

Abstract

A device for measuring a level of a physical condition includes a sensor configured to sense the physical condition and to produce an electrical output indicative of the sensed physical condition, the sensor having an input and an output, a direct voltage source connected to the sensor input, a current regulator connected in an electrical path between the direct voltage source and the sensor input, and a voltmeter connected in parallel with the sensor such that a voltage detected by the voltmeter is indicative of the level of the sensed physical condition.

Claims

1. A method comprising: providing a sensor configured to sense a physical condition and to produce an output signal indicative of the sensed physical condition, the sensor having an input and an output, electrically connecting a direct voltage source to the sensor, connecting a current regulator in an electrical path from the direct voltage source to the sensor, electrically connecting a voltmeter in parallel with the sensor, and determining a level of the sensed physical condition from the voltage detected by the voltmeter.

2. The method according to claim 1, wherein the current regulator has a precision tolerance of less than or equal to 0.2%.

3. The method according to claim 1, wherein the current regulator has a precision tolerance of less than or equal to 0.2%.

4. The method according to claim 3, wherein the physical quantity is a temperature or an acceleration.

5. An integrated circuit comprising a measuring device according to claim 1.

6. The method according to claim 1, wherein the physical condition is a condition of an environment in which the sensor is located.

7. A device for measuring a level of a physical condition comprising: a sensor configured to sense the physical condition and to produce an electrical signal indicative of the sensed physical condition, the sensor having an input and an output, a direct voltage source connected to the sensor input, a current regulator connected in an electrical path between the direct voltage source and the sensor input, and a voltmeter connected in parallel with the sensor, wherein a voltage detected by the voltmeter is indicative of the level of the sensed physical condition.

8. The device according to claim 7, wherein the current regulator has a precision tolerance of less than or equal to 0.2%.

9. The device according to claim 7, wherein the current regulator has a precision tolerance of less than or equal to 0.2%.

10. The device according to claim 7, wherein the physical condition is a temperature or an acceleration.

11. An integrated circuit comprising a measuring device according to claim 7.

12. The device according to claim 7, wherein the physical condition is a condition of an environment in which the sensor is located.

13. A circuit comprising: a DC voltage source having an input and an output, the voltage source being configured to produce a voltage output signal from the output, a current regulator having an input and an output, the current regulator input being configured to receive the voltage output signal and the current regulator being configured to produce a current output signal at the current regulator output, a sensor configured to sense a physical condition and produce an electrical signal indicative of the sensed physical condition, the sensor having a first connection and a second connection, the first connection being configured to receive the current output signal from the current regulator, and the second connection being connected to the input of the DC voltage source, and a voltmeter connected to the first connection and the second connection and configured to detect a voltage across the sensor, wherein the sensed voltage is indicative of a level of the sensed physical condition.

14. The circuit according to claim 13, wherein the physical condition is a condition of an environment in which the sensor is located.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention and its advantages will be better understood by studying the detailed description of a specific embodiment given by way of a non-limiting example and illustrated by the appended drawings in which:

[0031] FIGS. 1A and 1B illustrate a conventional measuring device.

[0032] FIGS. 2A and 2B schematically illustrate a measuring device according to a first and a second embodiment of the invention.

[0033] FIG. 3 is a schematic representation of a current regulator of the measuring device of FIG. 2.

DETAILED DESCRIPTION

[0034] FIGS. 1A and 1B show a measuring device 1 configured to measure two physical quantities such as temperature and acceleration.

[0035] In order to collect temperature data, the measuring device 1 of FIG. 1B includes a resistance temperature detector RTD with a typical resistance of 1000 ohm at 0° C. that is suitable for receiving a current with a precision tolerance of less than or equal to 0.2% to deliver accurate temperature values.

[0036] Of course, the resistance temperature detector may be replaced by any temperature sensor with the same tolerance interval.

[0037] To measure the acceleration, the measuring device 1 of FIG. 1A includes an accelerometer AC of conventional structure which may be supplied with a constant current with a wide tolerance of ±20%.

[0038] The resistance temperature detector RTD and the accelerometer AC are powered by a direct voltage source generator SC such as a battery, which delivers an electrical voltage V.sub.IN.

[0039] The generator SC is coupled to a current regulator PCS configured to deliver a constant direct current I.sub.0 and to a non-precision current generator NPCS configured to deliver a non-constant direct current I.sub.10.

[0040] In particular, the current regulator PCS is coupled to the resistance temperature detector RTD and the non-constant direct current NPCS is coupled to the accelerometer AC.

[0041] As the current regulator PCS has a precision tolerance of 0.2% in this example, it allows the resistance temperature detector RTD to be operational.

[0042] The connections are here established by two switches SW1 and SW2 wherein switch SW1 is configured to enable or disable the flow of current I.sub.10 from the non-constant direct current NPCS to power the accelerometer AC.

[0043] Similarly, switch SW2 is configured to enable or disable the flow of current I.sub.0 from the current regulator PCS to power the resistance temperature detector RTD.

[0044] As switches SW1 and SW2 are configured to select the sensor to be supplied according to the delivered current, this embodiment requires an addition of programmed modules to control switches SW1, SW2 and thus the selection between the accelerometer AC and the resistance temperature detector RTD.

[0045] In order to overcome the use of these components, FIGS. 2A and 2B illustrate only one current regulator PCS which can be coupled to the accelerometer AC or to the resistance temperature detector RTD.

[0046] To read the acceleration, the accelerometer AC is coupled in parallel, at nodes C and D, to a first voltmeter V1 configured to measure a voltage U.sub.CD at its terminals as shown in FIG. 2A.

[0047] As for the acceleration reading, the resistance temperature detector is coupled in parallel, at nodes E and F, to a second voltmeter V2 configured to measure a voltage U.sub.EF at its terminals as illustrated in FIG. 2B.

[0048] FIG. 3 shows a schematic representation of the PCS current controller with conventional circuitry that may be used in the measuring device. Alternatively, other types of PCS current controller may be used.

[0049] The current regulator PCS includes here an electronic amplifier OP which receives as an input the voltage V.sub.IN, delivered by the source generator SC.

[0050] The amplifier OP is configured to output a control voltage to drive a field effect transistor T.sub.R1 which is coupled to a bipolar transistor T.sub.R2.

[0051] The transistor T.sub.R1 is here configured to drive the bipolar transistor in order to output the regulated current I.sub.0 that will power the accelerometer AC and the resistance temperature detector RTD.

[0052] Furthermore, it should be noted that the gain of the amplifier OP depends on the parameters of the transistors T.sub.R1, T.sub.R2 and the resistors R1 and R2.

[0053] The invention is not limited to these embodiments but comprises all the variants. For example, other components may be connected between the accelerometer AC or the resistance temperature detector RTD as long as they do not influence the accuracy of the regulated current I.sub.0.

[0054] Representative, non-limiting examples of the present invention were described above in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Furthermore, each of the additional features and teachings disclosed above may be utilized separately or in conjunction with other features and teachings to provide improved devices for measuring two physical quantities.

[0055] Moreover, combinations of features and steps disclosed in the above detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Furthermore, various features of the above-described representative examples, as well as the various independent and dependent claims below, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings.

[0056] All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter.