Circuit configuration compensating for disturbance variables for a measurement pickup

• US 20010005134A1
• Filed: 12/14/2000
• Published: 06/28/2001
• Est. Priority Date: 12/14/1999
• Status: Abandoned Application

• Current Assignee: Jorg Friedel, Ludwig Schifferl
• Original Assignee: Jorg Friedel, Ludwig Schifferl
• Inventors: Friedel, Jorg, Schifferl, Ludwig
• Application Number:
  US09/737,059
• Publication Number:
  US 20010005134A1
• Time in Patent Office: Days
• US Class Current: 324/225
• CPC Class Codes: G01D 3/036 on measuring arrangements themselves

Abstract

A circuit configuration compensates for disturbance variables in a measurement pickup which has a measured-variable dependent resistance that is added from a fundamental resistance, which is independent of measured variables, and a measuring resistance, which is dependent on measured variables. The fundamental resistance and the measuring resistance are disturbance variable-dependent in opposite directions. A bridge circuit has two measurement pickups using difference evaluation to eliminate the disturbance variable dependency of the fundamental resistance. A bridge voltage controller sets the bridge diagonal voltage in the opposite direction to the disturbance variable dependency of the measuring resistance, and thus compensates for the disturbance variable-dependency of the measuring resistance.

Claims

1. A circuit configuration, comprising:

two measurement pickups each having a resistance dependent on measured variables, the resistance additively including a fundamental resistance independent of the measured variables, and a measuring resistance dependent on the measured variables, the fundamental resistance and the measuring resistance being disturbance variable-dependent in mutually opposite directions;

said two measurement pickups having mutually identical disturbance variable-dependency and being connected in a bridge circuit, with difference evaluation to eliminate the disturbance variable-dependency of the fundamental resistance; and

a bridge voltage controller connected to said bridge circuit for setting a bridge diagonal voltage in opposite direction to the disturbance variable dependency of the measuring resistance for eliminating the disturbance variable dependency of the measuring resistance.

2. The circuit configuration according to

claim 1

, wherein said bridge circuit includes a first series circuit of a resistor and one of said measurement pickups connected in parallel with a second series circuit of a resistor and the other of said measurement pickups, a differential amplifier tapping off a potential of each of said first and second series circuits at a respective node between said resistor and said measurement pickup.

3. The circuit configuration according to

claim 2

, wherein said bridge voltage controller has an operational amplifier with an inverting input, a non-inverting input, and an output, said bridge circuit is connected in a negative feedback path of said operational amplifier such that said measurement pickups are connected in parallel in a feedback path, said inverting input of said operational amplifier connected to ground via a resistor, and said noninverting input connected to receive feedback from said output of said operational amplifier via a resistor.

4. The circuit configuration according to

claim 3

, which comprises a resistor in the negative feedback path of said operational amplifier connected in series with said bridge circuit.

5. The circuit configuration according to

claim 2

, which comprises a resistor connected between a noninverting input of said differential amplifier to a reference voltage.

6. The circuit configuration according to

claim 1

, wherein the bridge circuit includes a parallel circuit comprising a respective said measurement pickup connected in series with a respective said resistor, and a differential amplifier is connected for tapping off a potential between the measurement pickups and said respective resistors in each case.

7. The circuit configuration according to

claim 6

, wherein said bridge voltage controller has an operational amplifier with an inverting input, a non-inverting input, and an output, said bridge circuit is connected in a negative feedback path of said operational amplifier such that said measurement pickups are connected in parallel in a feedback path, said inverting input of said operational amplifier connected to ground via a resistor, and said noninverting input connected to receive feedback from said output of said operational amplifier via a resistor.

8. The circuit configuration according to

claim 7

, which comprises a resistor in the negative feedback path of said operational amplifier connected in series with said bridge circuit.

9. The circuit configuration according to

claim 6

, which comprises a resistor connected between a noninverting input of said differential amplifier to a reference voltage.