Passenger judging apparatus with load sensor

• US 20030154805A1
• Filed: 02/14/2003
• Published: 08/21/2003
• Est. Priority Date: 02/20/2002
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Takafuji, Tetsuya, Suzuki, Tomoji
• Granted Patent: US 6,957,591 B2
• Time in Patent Office: Days
• US Class Current: 73/862.391
• CPC Class Codes: B60R 21/01516 using force or pressure sensing means
• CPC Class Codes: B60R 21/01556 Child-seat detection systems
• CPC Class Codes: G01G 19/4142 for controlling activation of safety devices, e.g. airbag systems electrical circuits for triggering safety arrangements in case of vehicle accidents B60R21/015

Abstract

In a passenger judging apparatus with a load sensor excellent in practical use and capable of achieving not only the reduction of judgment delay in the case of the necessity for a quick judgment but also the improvement of the judgment accuracy in the other cases, a judgment indicating the occurrence of a state transition forming a transition between classes is made only when a load detected stays continuously in a predetermined class for a predetermined threshold time period, with the threshold time period being variably set to be different in length among inter-class state transitions. This contributes greatly to the improvement of the judgment accuracy by eliminating erroneous judgment stemming from a false signal without uselessly delaying the judgment on the state transition requiring a quick decision.

Claims

1. A passenger judging apparatus comprising:

a load sensor for detecting a load acting on a seat of a vehicle; and

judging means for classifying said load, converted into a signal, as one of a multiplicity of classes according to a predetermined load threshold to make a judgment on the presence or absence of a passenger or a type thereof,

said judging means making a judgment indicating the occurrence of a state transition forming a transition between said classes when the detected load stays continuously in said class for a predetermined threshold time period, with said threshold time period being variably set to be different in length in determining at least a plurality of state transitions.

2. The apparatus according to claim 1, wherein said judging means has an “

unoccupied”

, an “

adult” and

a “

child”

as said classes, and said threshold time period for said state transition between said “

unoccupied” and

said “

adult”

or said “

child”

is set to be shorter than said threshold time period for said state transition from said “

adult”

to said “

child”

.

3. The apparatus according to claim 1, wherein said judging means has an “

unoccupied”

, an “

adult” and

a “

child”

as said classes, and said threshold time period for said state transition between said “

unoccupied” and

said “

adult”

or said “

child”

is set to be shorter than said threshold time period for said state transition from said “

child”

to said “

adult”

.

4. The apparatus according to claim 1, wherein said judging means has an “

unoccupied”

, an “

adult” and

a “

child”

as said classes, and said threshold time period for said state transition from said “

child”

to said “

adult”

is set to be shorter than said threshold time period for said state transition from said “

adult”

to said “

child”

.

5. The apparatus according to claim 1, wherein said judging means has an “

unoccupied”

, an “

adult” and

a “

child”

as said classes, and said threshold time period for said state transition from said “

adult”

or said “

child”

to said “

unoccupied”

is set to be shorter than said threshold time period for said state transition from said “

unoccupied”

to said “

adult”

or said “

child”

.

6. The apparatus according to claim 1, wherein said judging means makes a judgment on said state transition between said “

unoccupied”

constituting said class and another class on the basis of said load including a relatively large quantity of high-frequency signal component in comparison with a judgment on said state transition between said classes other than said “

unoccupied”

.

7. The apparatus according to claim 1, wherein said judging means has an “

unoccupied”

, an “

adult” and

a “

child”

as said classes, and at said state transition from said “

unoccupied”

to said “

adult”

or said “

child”

, said threshold time for a judgment on said state transition between said “

adult” and

said “

child”

is prolonged in a state correlated with the elapsed time from when a judgment is made that said “

unoccupied”

is canceled.

8. The apparatus according to claim 1, wherein said load sensor detects a distribution of a surface pressure on a sitting face of a seat, and said judging means compares said load forming the sum of said surface pressures detected by said load sensor with a predetermined first load threshold to make a judgment as to whether or not said class is said “

unoccupied”

, and calculates a value of a function having a correlation with a body dimension of a passenger on the basis of a two-dimensional distribution of said surface pressures to compare said function value with a predetermined second load threshold for making a judgment between said “

adult” and

said “

child”

.