VEHICLE OCCUPANT CLASSIFICATION SYSTEM

• US 20090143943A1
• Filed: 11/30/2007
• Published: 06/04/2009
• Est. Priority Date: 11/30/2007
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Technical Center North America Incorporated (Nissan Motor Co., Ltd.)
• Inventors: Jaramillo, Jamison, Gauger, Aaron J., Strunk, David
• Granted Patent: US 7,860,625 B2
• Time in Patent Office: Days
• US Class Current: 701/45
• CPC Class Codes: B60N 2/002 Seats provided with an occupancy detection means mounted therein or thereon detection means responsive to presence or absence of children B60N2/266
• CPC Class Codes: B60R 21/01516 using force or pressure sensing means
• CPC Class Codes: B60R 21/01526 using piezoelectric elements
• CPC Class Codes: B60R 21/01534 using electromagneticwaves, e.g. infrared
• CPC Class Codes: G01B 11/002 for measuring two or more coordinates
• CPC Class Codes: G01B 11/16 for measuring the deformation in a solid, e.g. optical strain gauge

Abstract

A vehicle seat pressure sensor includes a light source, a non-fiber optical polymer sheet, a boundary layer and a detection unit. The non-fiber optical polymer sheet is composed of non-woven flexible optical polymer material and has a first surface with a peripheral edge surrounding the first surface. The peripheral edge of the optical polymer sheet is aligned with the light source such that light emitted from the light source projects into the optical polymer sheet through the peripheral edge. The boundary layer is disposed along the first surface of the optical polymer sheet. The detection unit is disposed relative to the optical polymer sheet to detect changes in attenuation of light emitted from the peripheral edge of the optical polymer sheet in response to elastic deformation of the boundary layer and the optical polymer sheet.

Claims

1. A vehicle seat pressure sensor comprising:

a light source;

a non-fiber optical polymer sheet of non-woven flexible optical polymer material having a first surface with a peripheral edge surrounding the first surface aligned with the light source such that light emitted from the light source projects into the optical polymer sheet through the peripheral edge;

a boundary layer disposed along the first surface of the optical polymer sheet; and

a detection unit disposed relative to the optical polymer sheet to detect changes in attenuation of light emitted from the peripheral edge of the optical polymer sheet in response to elastic deformation of the boundary layer and the optical polymer sheet.

2. The vehicle seat pressure sensor according to claim 1, further comprising

a first optical insulating layer covering a second surface of the optical polymer sheet that is opposite the boundary layer;

and

a second optical insulating layer covering a surface of the boundary layer that is opposite the optical polymer sheet.

3. The vehicle seat pressure sensor according to claim 2, wherein

the detection unit detects dielectric capacitance changes of the optical polymer sheet and at least one of the first and second optical insulating layers in response to changes in dielectric capacitance proximate the at least one of the first and second optical insulating layers and the optical polymer sheet.

4. The vehicle seat pressure sensor according to claim 1, wherein

the light source and the detection unit are arranged perpendicularly to one another along the peripheral edge of the optical polymer sheet.

5. The vehicle seat pressure sensor according to claim 1, wherein

the light source and the detection unit are arranged opposite to one another along the peripheral edge of the optical polymer sheet.

6. The vehicle seat pressure sensor according to claim 1, wherein

the optical polymer sheet includes a plurality of optical polymer sheet sections defining a plurality of sensing zones with each of the sensing zones at least partially forming a part of the peripheral edge of the optical polymer sheet,

the light source is configured to emit a separate light beam to each of the sensing zones, and

the detection unit is disposed to separately detect the separate light beam from each of the sensing zones.

7. The vehicle seat pressure sensor according to claim 6, wherein

each of the optical polymer sheet sections has an L-shape with a first end disposed along the peripheral edge of the optical polymer sheet adjacent the light source and a second end disposed along the peripheral edge of the optical polymer sheet adjacent the detection unit.

8. The vehicle seat pressure sensor according to claim 7, wherein

the light source includes a first light emitting device disposed at a first location along the peripheral edge of the optical polymer sheet and a second light emitting device disposed at a second location along the peripheral edge of the optical polymer sheet.

9. The vehicle seat pressure sensor according to claim 7, wherein

the optical polymer sheet includes at least four of the optical polymer sheet sections with the L-shape that are arranged such that the first ends of a first pair of the at least four of the optical polymer sheet sections face in a first direction and a second pair of the at least four of the optical polymer sheet sections face in a second direction that is opposite the first direction.

10. The vehicle seat pressure sensor according to claim 1, farther comprising

a seat cushion portion having an upper outer surface and a lower outer surface with the vehicle seat sensor disposed within the cushion portion between the upper and lower outer surfaces.

11. The vehicle seat pressure sensor according to claim 1, wherein

the optical polymer sheet is a flat member with a second surface parallel to the first surface.

12. The vehicle seat pressure sensor according to claim 11, wherein

the optical polymer sheet has a thickness that is no greater than four millimeters as measured between the first and second surfaces.

13. The vehicle seat pressure sensor according to claim 12, wherein

the first and second surfaces have a first linear dimension that is at least 23 millimeters as measured perpendicular to the thickness of the optical polymer sheet.

14. The vehicle seat pressure sensor according to claim 13, wherein

the first and second surfaces have a second linear dimension that is at least 40 millimeters as measured perpendicular to the thickness and the first linear dimension of the optical polymer sheet.

15. The vehicle seat pressure sensor according to claim 12, further comprising:

a processing unit connected to the detection unit to estimate a weight and location of a load placed on the cushion portion and presence of a passenger based upon signals outputted by the detection unit.

16. The vehicle seat pressure sensor according to claim 15, wherein

the processing unit is configured to selectively provide a plurality of deployment arming signals to an airbag control system that correspond to one of a plurality of predetermined passenger categories, including no passenger, a child passenger, a first weight category passenger and a second weight category passenger.

17. The vehicle seat pressure sensor according to claim 1, wherein the attenuation changes detected by the detection unit include changes in at least one of phase, polarity and intensity of light.

18. A vehicle occupant classification system comprising:

a seat having a cushion portion with upper and lower outer surfaces;

an optical polymer sheet sensor disposed within the cushion portion between the upper and lower outer surfaces of the cushion portion and to detect a change in attenuation of light transmitted through the optical polymer sheet sensor; and

a processing unit connected to the optical polymer sheet sensor to estimate a weight and location of a load placed on the cushion portion and presence of a passenger based upon detected changes outputted by the optical sensor.

19. The vehicle occupant classification system according to claim 18, wherein

the processing unit is configured to selectively provide a plurality of deployment arming signals to an airbag control system, based upon the detected changes outputted by the optical polymer sheet sensor.

20. The vehicle seat pressure sensor according to claim 18, wherein the attenuation changes detected by the detection unit include changes in at least one of phase, polarity and intensity of light.

21. The vehicle occupant classification system according to claim 19, wherein

the deployment arming signals from the processing unit to airbag control system, correspond to one of a plurality of predetermined passenger categories, including no passenger, a child passenger, a first weight category passenger and a second weight category passenger.

22. The vehicle occupant classification system according to claim 18, wherein

the optical polymer sheet sensor comprises:

an optical polymer sheet of flexible optical polymer material;

a boundary layer disposed along at least one surface of the optical polymer sheet of flexible optical polymer material;

a light source configured to project light into a first edge of the optical polymer sheet; and

a detection unit operably connected to provide signals to the processing unit disposed along a second edge of the optical polymer sheet configured and arranged to detect changes in attenuation of light emitted from the second edge of the optical polymer sheet corresponding to elastic deformation of the boundary layer and the optical polymer sheet.

23. The vehicle occupant classification system according to claim 22, wherein

the optical polymer sheet sensor further comprises:

a first optical insulating layer covering a side of the optical polymer sheet opposite the boundary layer; and

a second optical insulating layer covering a side of the boundary layer opposite the optical polymer sheet.

24. The vehicle occupant classification system according to claim 23, wherein

the optical polymer sheet sensor is further configured to detect changes in dielectric capacitance of the optical sensor assembly and output detected changes in dielectric capacitance to the processing unit.

25. The vehicle occupant classification system according to claim 22, wherein

the optical polymer sheet sensor further comprises:

a plurality of optical polymer sheet sections defining a plurality of sensing zones with each of the sensing zones at least partially forming a part of the peripheral edge of the optical polymer sheet,

the light source is configured to emit a separate light beam to each of the sensing zones, and

the detection unit is disposed to separately detect the separate light beam from each of the sensing zones.

26. A method of making a seat cushion, comprising:

forming a first cushion portion with an upper seating surface and a lower joining surface with a recess formed in the lower joining surface;

inserting a flexible optical sensor into the recess of the first cushion portion with a lead wire harness extending from the flexible optical sensor along the lower joining surface; and

joining a second cushion portion to the lower joining surface of the first cushion portion to form the seat cushion with the lead wire harness from the optical sensor assembly being externally exposed with respect to the first and second cushions.