Integrated sensor

• US 5,756,899 A
• Filed: 04/30/1997
• Issued: 05/26/1998
• Est. Priority Date: 05/01/1996
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Shoji, Yasunori, Ugai, Seiichi, Shimizu, Yasushi
• Primary Examiner(s): Dombroske, Geroge M.
• Assistant Examiner(s): AMROZOWICZ, PAUL DOUGLAS
• Application Number:
  US08/846,936
• Time in Patent Office: 391 Days
• Field of Search: 73/714, 73/716, 73/717, 73/718, 73/719, 73/720, 73/721, 73/723, 73/724, 73/725, 73/726, 73/727, 73/700, 73/335.04, 73/335.05
• US Class Current: 73/714
• CPC Class Codes: G01F 1/383 with electrical or electro-mechanical indication
• CPC Class Codes: G01F 23/18 Indicating, recording or alarm devices actuated electrically
• 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 19/0627 Protection against aggressive medium in general
• CPC Class Codes: G01L 9/0072 using variations in capacitance
• CPC Class Codes: G01N 33/18 Water

Abstract

The first glass substrate having the first pressure admitting entrance for leading the pressure of fluid to be measured, is arranged at a side of a diaphragm of a pressure sensor, for measuring differential pressure. The second glass substrate is arranged at the side opposite to the first glass substrate, a spacer being sandwiched therebetween. The second pressure admitting entrance is formed at the second glass substrate, at the position opposite to the first presser admitting entrance of the first glass substrate. The first conductive film and the second conductive film are formed on two surfaces facing to each other, of the first and second glass substrates, respectively. By measuring the specific conductance and the dielectric constant of the object fluid between the two conductive films, these physical constants indicating the quality of the fluid, the quality of the fluid can be also detected. Thus, it becomes possible to realize and provide an integrated sensor capable of measuring the differential pressure (flow rate) and the quality of fluid by using one transmitter.

Claims

1. An integrated sensor, comprising:

a pressure sensor including a diaphragm displacing corresponding to a pressure of an object substance to be measured;

a first substrate connected to said diaphragm, possessing a first pressure admitting entrance for leading said pressure of said substance to be measured, to said diaphragm, and a first conductive film formed on said first substrate;

a second substrate possessing a second pressure admitting entrance for leading said pressure of said substance to be measured, to said diaphragm via said first pressure admitting entrance, and a second conductive film at a position facing to said first conductive film, which is separated with a predetermined interval; and

a signal processing unit for measuring at least one of a specific conductance and a dielectric constant of said substance filled between said first conductive film and said second conductive film, and said pressure of said substance, by using output signals transmitted from said pressure sensor.

2. An integrated sensor according to claim 1, wherein said diaphragm in said pressure sensor is made of single crystal silicon, at which a temperature-sensitive element is provided, and said signal processing unit measures a temperature of substance in the vicinity of said pressure sensor by using an output signal transmitted from said temperature-sensitive element.

3. An integrated sensor according to claim 1, wherein at least a strain-sensitive gauge element is provided at a surface of said diaphragm in said pressure sensor, and another surface of said diaphragm is connected to said first substrate.

4. An integrated sensor according to claim 1, wherein at least a strain-sensitive gauge element is provided at a surface of said diaphragm in said pressure sensor, said surface of said diaphragm at which said strain-sensitive gauge element is connected to said first substrate.

5. An integrated sensor according to claim 1, wherein a first electrode plate is provided at a position facing to said diaphragm, of said first substrate, said diaphragm being a conductive electrode, and a second electrode plate is provided at a position opposite to said first electrode plate so that said first and second electrode plate sandwiches said diagram, and said signal processing unit measures said pressure of said substance, based on a difference between, an electrostatic capacity between said first electrode plate and said diaphragm and an electrostatic capacity between said second electrode plate and said diaphragm.

6. An integrated sensor according to claim 1, wherein said pressure sensor is made of single crystal silicon, said first substrate is made of boro-silicated glass, and said pressure sensor is airtightly connected to said first substrate by a anodic bonding method.

7. An integrated sensor according to claim 1, wherein said pressure sensor is made of single crystal silicon, and an oxidation film is formed at a surface area exposed to said substance, of said pressure sensor.

8. An integrated sensor according to claim 1, wherein said pressure sensor is made of single crystal silicon, and a nitriding film is formed at a surface area exposed to said substance, of said pressure sensor.

9. An integrated sensor according to claim 1, wherein said pressure sensor is made of single crystal silicon, and a corrosion-resistant metal film is formed at a surface area exposed to said substance, of said pressure sensor.

10. An integrated sensor according to claim 1, wherein each of said first conductive film and said second conductive film is made of a corrosion-resistant metal film.

11. An integrated sensor according to claim 1, wherein, for at least one of said first substrate and said second substrate, a through-hole is provided for electrically connecting a conductive film on a surface of said substrate and a conductive film on another surface of said substrate.

12. An integrated sensor according to claim 1, wherein said first conductive film and said second conductive film are connected to terminals provided at said signal processing unit via electrical connection wires, and a covering member for protecting said first conductive film, said second conductive film and said electrical connection wires from said substance, is attached to at least said second substrate.

13. An integrated sensor according to claim 1, wherein said pressure of said substance is led to a surface of said diaphragm via said first pressure admitting entrance and said second pressure admitting entrance, and another surface of said diaphragm is contained in an isolation chamber.

14. An integrated sensor according to claim 13, wherein a pressure of said isolation chamber is kept constant.

15. An integrated sensor according to claim 13, wherein said isolation chamber is kept as an almost vacuum state.

16. An integrated sensor according to claim 13, wherein at least one pressure leading path to said isolation chamber is provided to set said pressure of said isolation chamber as a desired level.

17. An integrated sensor according to claim 13, wherein said substance to be measured is liquid, a pressure of said liquid is led to said a surface of said diaphragm, and a pressure leading path to said isolation chamber is provided to set said pressure of said isolation chamber as an atmosphere pressure.

18. An integrated sensor according to claim 13, wherein said substance is fluid flowing in a pipe in which an orifice is provided, a pressure of said fluid in the upstream of said orifice is led to a surface of said diaphragm via said first pressure admitting entrance and said second pressure admitting entrance, and a pressure leading path is connected to said isolation chamber, in order to lead a pressure of said fluid in the downstream of said orifice to another surface of said diaphragm.

19. An integrated sensor according to claim 17, wherein at least a part of the signal processing unit is placed over a surface of liquid, which is separated from and connected to said pressure sensor with a water-proofing wire.

20. An integrated sensor according to claim 17, wherein at least a part of the signal processing unit is placed over a surface of liquid, which is separated from and electrically connected to said pressure sensor, a pressure leading path is connected between said signal processing unit and said isolation chamber, and at least a signal transmitting wire for connecting said signal processing unit and said pressure sensor is provided in said pressure leading path.

21. A fluid management system including a fluid storing part, a fluid feeding part with a first control valve, for flowing said fluid into said fluid storing part, a fluid draining part with a second control valve, for draining said fluid from said fluid storing part, a control part for adjusting a level of said fluid in said fluid storing part by controlling said first control valve at said fluid feeding part and said second control valve at said fluid draining part,

wherein said integrated sensor according to claim 17 is arranged in said fluid storing part, and said control part for adjusting said level of fluid in said fluid storing part by controlling said first control valve, detects the specific conductance of said fluid expressing a quality of said fluid, and generates an alarm if the detected specific conductance is out of a predetermined range, based on output signals transmitted from said integrated sensor.