Thermal effect and off-center load compensation of a sensor

• US 8,191,428 B2
• Filed: 12/28/2007
• Issued: 06/05/2012
• Est. Priority Date: 12/28/2007
• Status: Active Grant

• Current Assignee: Ypoint Capital, Inc,
• Original Assignee: Ypoint Capital, Inc,
• Inventors: Harish, Divyasimha
• Primary Examiner(s): Noori, Max
• Application Number:
  US11/965,737
• Publication Number:
  US 20090167327A1
• Time in Patent Office: 1,621 Days
• Field of Search: 351/47, 351/48, 351/57, 351/58, 351/44, 351/153, 351/158, 162/28, 737/80, 738/620.9, 737/60
• US Class Current: 73/780
• CPC Class Codes: G01L 1/142 using capacitors
• CPC Class Codes: G01L 19/04 Means for compensating for effects of changes of temperature , i.e. other than electric compensation
• CPC Class Codes: G01L 9/0075 using a ceramic diaphragm, e.g. alumina, fused quartz, glass
• CPC Class Codes: Y10T 29/53174 Means to fasten electrical component to wiring board, base, or substrate

Abstract

A method and system of thermal effect and off-center load compensation of a sensor are disclosed. In one embodiment, a sensor includes a first conductive surface and a second conductive surface substantially parallel to the first conductive surface, a processing and communication zone of the first conductive surface and the second conductive surface having circuitry to enable communication with an external system (e.g., using a Universal Serial Bus (USB) interface) and a sensing area having partially a ceramic substrate surrounding a sensor surface and a reference surface of the first conductive surface and the second conductive surface. The sensor may include a set of electrical leads that enable the sensing area to communicate with the processing and communication zone and with external devices, and a guard ring surrounding the first conductive surface and the second conductive surface to minimize an effect of stray capacitance.

Claims

1. A sensor, comprising:

a first conductive surface;

a second conductive surface substantially parallel to the first conductive surface;

a processing and communication zone of at least one of the first conductive surface and the second conductive surface having circuitry to enable communication with an external system; and

a sensing area having at least partially a ceramic substrate surrounding at least one of a sensor surface and a reference surface of the at least one of the first conductive surface and the second conductive surface,

wherein a jig having a preset force is configured to be applied to the ceramic substrate and a housing of the sensor to minimize hysteresis of the sensor.

2. The sensor of claim 1, wherein the circuitry to enable communication with the external system comprises a Universal Serial Bus (USB) interface.

3. The sensor of claim 1, wherein the circuitry is a wireless enabled circuitry that enables the sensor to operate through a wireless network including at least one of a Bluetooth®

network, a WiFi™

network, and a ZigBee™

network.

4. The sensor of claim 1, wherein a portion of at least one of the processing and communication zone and the sensing area is fabricated with a FR4 printed circuit board material adjacent to the ceramic substrate to reduce a cost of manufacture of the sensor.

5. The sensor of claim 1, further comprising:

a set of electrical leads that enable the sensing area to communicate with the processing and communication zone and with at least one external device, and

a guard ring surrounding the at least one of the first conductive surface and the second conductive surface to minimize an effect of stray capacitance.

6. The sensor of claim 1, wherein the ceramic substrate comprises alumina created through a form of aluminum oxide, Al₂O₃, occurring naturally as corundum, in a hydrated form in bauxite, and with various impurities including ruby, sapphire, and emery.

7. The sensor of claim 1,

wherein the ceramic substrate has a low thermal expansion coefficient that is well matched to the housing of the sensor, and

wherein the housing of the sensor comprises a stainless steel material.

8. The sensor of claim 1, wherein a film material bonds the ceramic substrate to the housing of the sensor after a roughness pattern is introduced on the housing to better secure the bond between the ceramic substrate and the housing of the sensor, the film material providing for a more linear thermal characteristic, thereby making error correction of the sensor simpler.

9. The sensor of claim 8, wherein the roughness pattern is a spiral groove pattern.

10. The sensor of claim 1, wherein the ceramic substrate is attached to the housing using three stainless steel spacers of 10 mils a piece.

11. The sensor of claim 1, wherein a glass layer is created between the housing and the ceramic substrate such that the ceramic substrate rests above the glass layer separating the ceramic substrate from the housing.

12. The sensor of claim 1, wherein the ceramic substrate is directly fused to the housing using a 900 degree F. temperature process optimized to minimize air bubbles between the ceramic substrate and the housing.

13. The sensor of claim 1, wherein multiple sensing zones make up the sensor surface to minimize tilt in case of off-center loading.

14. The sensor of claim 13, further comprising a curved surface of at least one of the sensor surface, first conductive surface, and the second conductive surface to keep an area between a set of plates predictable when the off-center loading occurs.

15. The sensor of claim 13 ,further comprising a double-diaphragm sensor with a hollow interior cavity housing surrounding a solid central portion to minimize tilt effects due to the off-center loading, the double-diaphragm sensor having physical properties of a three dimensional four bar linkage swept across an axis.

16. A sensor, comprising:

a first conductive surface;

a second conductive surface substantially parallel to the first conductive surface;

a processing and communication zone of at least one of the first conductive surface and the second conductive surface having circuitry to enable communication with an external system;

a set of electrical leads that enable the sensing area to communicate with the processing and communication zone and with at least one external devices;

a guard ring surrounding the at least one of the first conductive surface and the second conductive surface to minimize an effect of stray capacitance; and

a sensing area having at least partially a ceramic substrate surrounding at least one of a sensor surface and a reference surface of the at least one of the first conductive surface and the second conductive surface,

wherein a jig having a preset force is configured to be applied to the ceramic substrate and the housing to minimize hysteresis of the sensor.

17. The sensor of claim 16, wherein at least one of:

a film material bonds the ceramic substrate to the housing of the sensor after a roughness pattern is introduced on the housing to better secure the bond between the ceramic substrate and the housing of the sensor,

the roughness pattern is a spiral groove pattern, and

the film material provides for a more linear thermal characteristic, thereby making error correction of the sensor simpler.

18. A sensor, comprising:

a ceramic substrate surrounding at least one of a sensor surface and a reference surface of the sensor; and

a film material to bond the ceramic substrate to a housing of the sensor after a roughness pattern is introduced on the housing to better secure the ceramic substrate and the housing of the sensor,

wherein the sensor includes a hollow interior cavity in a double-diaphragm form surrounding a solid central portion to minimize tilt effects due to off-center loading, the double-diaphragm form having physical properties of a three dimensional four bar linkage swept across an axis.

19. The sensor of claim 18, wherein at least one of:

the roughness pattern is a spiral groove pattern, and

the film material provides for a more linear thermal characteristic, thereby making error correction of the sensor simpler.

20. The sensor of claim 18, wherein at least one of:

a jig having a preset force is configured to be applied to the ceramic substrate and the housing to minimize hysteresis of the sensor, and

the film material compresses from 3 mils to 1 mil when 350 degrees F. temperature is applied for 10 minutes using a thermoset process.