Magnetostrictive sensor device having one interface providing information regarding mode converter signal volatage and sensed object position

• US 6,583,615 B1
• Filed: 08/03/2000
• Issued: 06/24/2003
• Est. Priority Date: 08/05/1999
• Status: Expired due to Fees

• Current Assignee: Leopold Kostal GmbH & Company KG
• Original Assignee: Leopold Kostal GmbH & Company KG
• Inventors: Kathol, Meinolf
• Primary Examiner(s): Strecker, Gerard R.
• Application Number:
  US09/631,216
• Time in Patent Office: 1,055 Days
• Field of Search: 324/207.12, 324/207.13, 324/207.22, 324/207.24, 732/90.R, 733/13, 733/14, 732/90.V, 367/98, 367/900, 367/908
• US Class Current: 324/207.13
• CPC Class Codes: G01D 5/485 using magnetostrictive devices

Abstract

A sensor device for detecting a physical measurement variable is proposed including a sensor module as well as an electronic circuit module, wherein each value of the measurement variable is determined by comparison of an electrical voltage signal generated in the sensor module with a reference voltage generated in the circuit module and each value is output as a digital or analog coded signal at an output. Such a sensor device should solve the technical problem of making information about the amplitude of an internal electrical voltage signal accessible at all times for evaluation of the current tolerance situation. This is achieved in that the amplitude of this electrical voltage signal is represented by the period of a delay between the activation of the supply voltage for the sensor device and the output of the first valid measurement value.

Claims

1. A magnetostrictive sensor device comprising:

a delay line;

a pulse generator coupled to the delay line for periodically generating electrical current pulses in the delay line from an initial starting time;

a magnet located proximate the delay line for converting the current pulses propagating in the delay line into acoustic pulses propagating in the delay line;

a mode converter coupled to the delay line for detecting the acoustic pulses and converting the acoustic pulses into corresponding mode converter signals, each having an electrical voltage indicative of the corresponding acoustic pulse;

a reference voltage signal generator for generating a reference voltage signal having an electrical voltage which increases in accordance with a known function over time from the initial starting time;

a comparator coupled to the mode converter and the reference voltage signal generator for comparing each mode converter signal to the reference voltage signal, wherein the comparator switches when the voltage of a mode converter signal at a given time after the initial starting time becomes equal to the voltage of the reference voltage signal, wherein the comparator switches a second time when the voltage of the next mode converter signal occurring after the given time is equal to the voltage of the reference voltage signal; and

a logic component coupled to the comparator and the reference voltage generator, wherein the logic component causes the reference voltage generator to maintain the voltage of the reference voltage signal upon the comparator switching at the given time, the logic component being operable for, upon the comparator switching the second time, outputting an output signal indicative of the given time and the time period between the mode converter signal at the given time and the next succeeding mode converter signal occurring after the given time;

wherein the voltage of the mode converter signal at the given time is determined using the known function and the given time indication provided by the output signal.

2. The sensor device of claim 1 wherein:

the position of the magnet with respect to the delay line is determined from the output signal as a function of the time period between the mode converter signal at the given time and the next succeeding mode converter signal occurring after the given time.

3. The sensor device of claim 1 wherein:

the voltage of the reference voltage signal increases linearly over time.

4. The sensor device of claim 1 wherein:

the voltage of the reference voltage signal increases over time in accordance with a logarithmic function.

5. The sensor device of claim 1 wherein:

the comparator generates a pulse-width modulated signal after switching.

6. The sensor device of claim 1 wherein:

the comparator generates a coded analog voltage signal after switching.

7. The sensor device of claim 1 wherein:

the delay line is a ferromagnetic delay line.

8. The sensor device of claim 1 wherein:

the magnet is a permanent magnet.

9. A method for use with a magnetostrictive sensor device, the method comprising:

coupling a pulse generator to a delay line for periodically generating electrical current pulses in the delay line from an initial starting time;

locating a magnet proximate the delay line for converting the current pulses propagating in the delay line into an acoustic pulses propagating in the delay line;

detecting the acoustic pulses and converting the acoustic pulses into corresponding mode converter signals each having an electrical voltage indicative of the corresponding acoustic pulse;

generating a reference voltage signal having an electrical voltage which increases in accordance with a known function over time from the initial starting time;

comparing each mode converter signal to the reference voltage signal;

generating a switch signal when the voltage of a mode converter signal at a given time after the initial starting time becomes equal to the voltage of the reference voltage signal;

generating a second switch signal when the voltage of the next mode converter signal occurring after the given time is equal to the voltage of the reference signal;

causing the voltage of the reference voltage signal to be maintained upon the generation of the switch signal at the given time;

upon the generation of the second switch signal, outputting an output signal indicative of the given time and the time period between the mode converter signal at the given time and the next succeeding mode converter signal occurring after the given time; and

determining the voltage of the mode converter signal at the given time using the known function and the given time indication provided by the output signal.