Temperature sensor

• US 4,332,081 A
• Filed: 07/10/1980
• Issued: 06/01/1982
• Est. Priority Date: 06/22/1978
• Status: Expired due to Term

• Current Assignee: North American Philips Corp. (Koninklijke Philips N.V.)
• Original Assignee: North American Philips Corp. (Koninklijke Philips N.V.)
• Inventors: Francis, Gaylord L.
• Primary Examiner(s): Gilden, Leon
• Application Number:
  US06/168,842
• Time in Patent Office: 691 Days
• Field of Search: 338/25, 338/195, 338/22 R, 338/22 SD, 338/260, 338/307-309, 338/319, 338/320, 73/362 AR, 29/610, 29/612, 29/613, 29/620, 29/626, 29/627, 29/611
• US Class Current: 29/612
• CPC Class Codes: G01K 7/223 characterised by the shape of the resistive element
• CPC Class Codes: H01C 17/24 by removing or adding resistive material H01C17/23, H01C17/232, H01C17/235 take precedence
• CPC Class Codes: Y10T 29/49085 Thermally variable

Abstract

A temperature sensor is constructed as a bridge circuit using thick film technology. Both thermistor and resistor thick film inks are applied to a substrate to form a bridge circuit for producing a highly sensitive and accurate indicator when a predetermined temperature has been reached. The resistor thick film circuit is laser scribed at a specific temperature value for greater accuracy.

Claims

1. A method of adjusting the resistance of a temperature sensor comprising:

printing a plurality of first resistive material films, at least one second resistive material film forming a thermistor and a plurality of conductive termination films on the surface of a non-conductive substrate in a partially overlapping pattern to provide an electrical network;

firing said substrate to bond said films to said substrate and fix their properties;

immersing said substrate having said fired, formed films in a liquid bath maintained at a precise temperature, said temperature being the exact temperature at which said temperature sensor is to be responsive;

measuring the resistance through each of said resistive films while said films are in said bath;

removing said substrate from said bath;

trimming the resistance of at least one of said first resistive films to a precise resistance value.