Differential pressure transmitter

• US 5,012,677 A
• Filed: 11/23/1988
• Issued: 05/07/1991
• Est. Priority Date: 11/27/1987
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Ugai, Seiichi, Shimizu, Yasushi, Shimada, Satoshi
• Primary Examiner(s): Woodiel, Donald O.
• Application Number:
  US07/275,580
• Time in Patent Office: 895 Days
• Field of Search: 73/756, 73/720, 73/721, 73/726, 73/727, 73/706, 73/708, 73/DIG. 4, 73/182, 338/4
• US Class Current: 73/721
• CPC Class Codes: G01L 13/025 using diaphragms
• CPC Class Codes: G01L 19/0092 Pressure sensor associated with other sensors, e.g. for measuring acceleration or temperature G01L9/025, G01L9/045, G01L9/065, G01L9/085, G01L9/105, G01L9/125, G01L19/02, G01L19/04 take precedence; measuring two or more variable G01D21/02; temperature sensors with pressure compensation G01K1/26
• CPC Class Codes: G01L 19/0645 using isolation membranes, specially adapted for protection
• CPC Class Codes: G01L 19/147 Details about the mounting of the sensor to support or covering means
• CPC Class Codes: G01L 19/148 Details about the circuit board integration, e.g. integrated with the diaphragm surface or encapsulation

Abstract

A differential pressure transmitter is an improvement over the drawbacks of conventional apparatuses and provides a differential pressure transmitter which compensates for adverse effects of a static pressure by using a static pressure detecting piezoresistive gauge. The transmitter includes a highly sensitive static pressure sensor with high outputs, and a composite sensor with small crosstalk between the static pressure sensor and a differential pressure sensor. The differential pressure transmitter is constructed of semiconductor sensor substrate and a fixed mount on which the sensor substrate is securely mounted; whereby the differential pressure of a fluid is detected by utilizing the difference in Young'"'"'s modulus between the sensor substrate and the mount. The sensor substrate is processed on one side or on both sides to make a part of the sensor substrate thinner than the surrounding parts and thereby cause a peak stress due to a static pressure load to occur at the thin part, and a change in resistance of a semiconductor piezoresistive gauge formed at that thin portion is detected.

Claims

1. A differential pressure transmitter, comprising:

a sensor substrate;

a mount holding said sensor substrate;

a differential pressure sensor formed on one portion of said sensor substrate; and

a static pressure sensor, sensing a static pressure of a fluid by utilizing a difference in Young'"'"'s modulus between the sensor substrate and the mount, formed on another portion of the sensor substrate;

wherein the sensor substrate has a first groove so that said static pressure sensor detects a peak stress caused by a static pressure, and the sensor substrate also has a second groove formed between the differential pressure sensor and the static pressure sensor to reduce crosstalk between the two sensors.