Thermoelectric product and method

• US 6,074,089 A
• Filed: 01/30/1998
• Issued: 06/13/2000
• Est. Priority Date: 01/31/1997
• Status: Expired due to Term

• Current Assignee: Omega Engineering Incorporated (Spectris PLC)
• Original Assignee: Omega Engineering Incorporated (Spectris PLC)
• Inventors: Baghai, Shahin, Macchiarelli, Michael A. Jr., Hollander, Milton Bernard, McKinley, William Earl
• Primary Examiner(s): Gibson, Randy W.
• Application Number:
  US09/015,928
• Time in Patent Office: 865 Days
• Field of Search: 374/171, 374/181
• US Class Current: 374/181
• CPC Class Codes: G01D 3/022 having an ideal characteristic, map or correction data stored in a digital memory
• CPC Class Codes: G01K 7/13 Circuits for cold-junction compensation

Abstract

A thermoelectric cold junction compensator connector module, for use with a thermoelectric device such as a thermistor, thermocouple, or resistance-temperature device, has within a housing a cold junction compensator circuit which has means for linearization of voltage output of the circuit relative to input to the circuit. Preferably the circuit also includes potentiometer means for adjustment of at least one parameter of the circuit, and means for adjustment of its voltage output to correspond to degrees Centigrade and degrees Fahrenheit. In a preferred form there are included within the housing a pair of input terminals shielded by ferrite material against stray electromagnetic induction signals, a printed circuit board which comprises a cold junction compensation circuit, a signal linearization circuit, a converter/amplifier circuit, and a circuit for selectively providing a degree Centigrade and degree Fahrenheit output, a battery power supply, and a battery status indicator with means for bringing it into and out of operation, a plurality of potentiometers for preliminary setting up of the circuits, an on-off switching means for the powered circuits, and output terminal means for connection to, for example, a voltmeter or a voltage recording device. The compact body may have a base portion on which the circuits and other items are mounted, and one or more removable cover portions securable on the base portion.

Further, a thermocouple voltage-to-analog connector is in the form of a compact hand-held module which contains all the components and power supplies for converting an input of thermocouple output voltage to a linear and cold-junction-compensated analog output. A particularly advantageous feature is that an on-board analog-to-digital converter only calculates and provides the linearity correction, necessary for the specific thermocouple at a specific temperature, in the form of a pulse width modulation signal output, so that about 95% of the analog output is derived from the output of a thermocouple amplifier and temperature sensor, and only 5% of the remaining signal is derived from the on-board micro-processor.

Claims

1. In a hand-held thermoelectric cold junction compensator connector module comprising:

(i) a thermocouple connector housing;

(ii) a cold junction compensator circuit mounted within said housing; and

including input and output means;

(iii) input terminal means on said housing connected to said input means or said compensator circuit;

(iv) a signal linearization circuit mounted within said housing and including input mean and output means, said input means being connected to said output means of said compensator circuit;

(v) converter/amplifier means in said housing having input means and output means, said input means being connected to said output means of said signal linearization circuit;

(vi) output terminal means on said housing connected to said output means of said converter/amplifier means;

(vii) a logic circuit in said housing connected to said signal linearization circuit and constructed to provide selectively degree Centigrade and degree Fahrenheit correction to the output of said signal linearization circuit;

(viii) battery power supply means disposed within said housing and connected to supply power to said cold junction compensator circuit, to said signal linearization circuit, to said logic circuit, and to said converter/amplifier circuit, the improvement comprising;

said logic circuit further including

a microprocessor having an eight bit analogue to digital converter which provides both linearity correction, as a pulse width modulation signal, and also provides thermoelectric cold junction compensation.