Occupant detection system

• US 20100171515A1
• Filed: 12/12/2009
• Published: 07/08/2010
• Est. Priority Date: 12/11/2008
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Ito, Hiroyuki, Yamanaka, Shoichi, Nakagawa, Hajime
• Granted Patent: US 8,193,820 B2
• Time in Patent Office: Days
• US Class Current: 324/658
• 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 21/01532 using electric or capacitive field sensors

Abstract

An occupant detection system is a part of a vehicle occupant protection system. The vehicle occupant protection system is enabled to be activated when the occupant detection system determines an ON state indicative of existence of an occupant on a seat. The vehicle occupant protection system is disabled to be activated when the occupant detection system determines an OFF state. The system includes a capacitive sensor which detects the occupant based on a capacitance around the seat. The system determines the ON state or the OFF state based on the detected value of the capacitive sensor and a predetermined threshold value. The system evaluates whether the determination result in the determination block is appropriate or not. Then, the system biases the threshold value to suppress a reversal determination from the determination result which is evaluated as appropriate.

Claims

1. An occupant detection system, comprising:

a capacitive sensor arranged on a seat in a vehicle;

a determination block which determines whether it is in an OFF state where an occupant protecting device is disabled or in an ON state where the occupant protecting device is enabled based on a comparison between a detected value of the capacitive sensor and a predetermined threshold value;

an evaluation block which evaluates whether the determination result in the determination block is appropriate or not; and

a correction block which biases the determination block so as to suppress a reversal determination from the determination result which is evaluated as appropriate by the evaluation block.

2. The occupant detection system in claim 1, wherein

the evaluation block evaluates whether an initial determination result determined by the determination block is appropriate or not.

3. The occupant detection system in claim 1, wherein

the correction block biases the determination block so as to reduce frequency of temporary reversal of the determination result, when the determination result is evaluated as appropriate.

4. The occupant detection system in claim 3, wherein

the correction block biases the threshold value in the determination block.

5. The occupant detection system in claim 1, wherein

the evaluation block detects a temporary reversal of the determination result, then, evaluates whether the determination result determined before the temporary reversal is detected is appropriate or not.

6. The occupant detection system in claim 1, wherein

the evaluation block evaluates that the determination result is appropriate, when a ratio of time of the determination result within a predetermined time period exceeds a predetermined ratio.

7. The occupant detection system in claim 1, wherein

the evaluation block evaluates that the determination result is appropriate, when duration of the determination result exceeds a predetermined time period.

8. The occupant detection system in claim 1, wherein

the evaluation block includes means for calculating a time ratio of the OFF state and/or the ON state within a predetermined time period, and

the correction block includes means for changing the threshold value to a predetermined value according to the time ratio calculated in the time ratio calculating means.

9. The occupant detection system in claim 8, wherein

the threshold value changing means increases the threshold value to a predetermined value, when the time ratio of the OFF state is equal to or higher than a predetermined ratio.

10. The occupant detection system in claim 8, wherein

the threshold value changing means decreases the threshold value to a predetermined value, when the time ratio of the ON state is equal to or higher than a predetermined ratio.

11. The occupant detection system in claim 1, wherein

the evaluation block includes means for determining a continuing state where the determination result is continuously maintained for a predetermined time period in a returned OFF state, when the determination result is returned again to the returned OFF state from the ON state after the determination result once reversed from the OFF state to the ON state, and

the correction block includes means for changing the threshold value increasingly to a predetermined value, when the continuing state determining means determines that the continuing state.

12. The occupant detection system in claim 1, wherein

the evaluation block includes means for determining a continuing state where the determination result is continuously maintained for a predetermined time period in a returned ON state, when the determination result is returned again to the returned ON state from the OFF state after the determination result once reversed from the ON state to the OFF state, and

the correction block includes means for changing the threshold value decreasingly to a predetermined value, when the continuing state determining means determines that the continuing state.

13. The occupant detection system in claim 1, wherein

the evaluation block includes means for determining whether it is in a first continuing state or a second continuing state,

the first continuing state being a state where the determination result is continuously maintained for a predetermined time period in a returned OFF state, when the determination result is returned again to the returned OFF state from the ON state after the determination result once reversed from the OFF state to the ON state, and the second continuing state being a state where the determination result is continuously maintained for a predetermined time period in a returned ON state, when the determination result is returned again to the returned ON state from the OFF state after the determination result once reversed from the ON state to the OFF state, and wherein

the correction block includes means for changing the threshold value increasingly to a predetermined value, when the continuing state determining means determines that the first continuing state, and for changing the threshold value decreasingly to a predetermined value, when the continuing state determining means determines that the second continuing state.