Passenger seat having occupant detector for automotive vehicle

• US 20080011732A1
• Filed: 07/03/2007
• Published: 01/17/2008
• Est. Priority Date: 07/11/2006
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Ito, Hiroyuki, Yamanaka, Shoichi, Kamizono, Tsutomu
• Granted Patent: US 7,928,341 B2
• Time in Patent Office: Days
• US Class Current: 219/217
• 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: B60N 2/0033 mounted on or in the foam cushion
• CPC Class Codes: B60N 2/0035 characterised by the sensor data transmission, e.g. wired connections or wireless transmitters therefor; characterised by the sensor data processing, e.g. seat sensor signal amplification or electric circuits for providing seat sensor information
• CPC Class Codes: B60N 2/5685 Resistance
• CPC Class Codes: B60N 2210/12 Capacitive; Electric field
• CPC Class Codes: Y10T 29/49826 Assembling or joining

Abstract

An electrode unit for detecting whether a seat is occupied or not (occupancy conditions) is embedded in a seat of an automotive vehicle together with an electrically powered seat heater. Both of the electrode unit and the seat heater are flat, and the electrode unit is laminated on the heat heater. The electrode unit is composed of an upper electrode, a lower electrode and an insulating film disposed between both electrodes. The occupancy conditions are detected based on changes in a capacitance between the upper electrode and a member grounded to a vehicle body. To reduce a capacitance between the upper electrode and seat heater and to thereby improve sensitivity of the detection of the occupancy conditions, an alternating voltage that alternates in accordance with an alternating voltage supplied to the upper electrode is supplied to the lower electrode.

Claims

1. A passenger seat device for an automotive vehicle, comprising:

a seat heater embedded in a seat in parallel to a seat surface, electric current being supplied to the seat heater in a controlled manner from an on-board power source;

an upper electrode embedded in the seat above the seat heater in parallel thereto;

an alternating current power source for supplying an alternating voltage having a predetermined frequency to the upper electrode; and

a detector for detecting occupancy conditions of the seat based on changes in a capacitance between the upper electrode and a member grounded to a vehicle body, wherein;

the passenger seat device further includes a lower electrode embedded in the seat between the upper electrode and the seat heater in parallel thereto; and

the alternating current power source supplies to the lower electrode a shielding alternating voltage that changes in accordance with the alternating voltage supplied to the upper electrode.

2. The passenger seat device as in claim 1, wherein:

the upper electrode is fixedly disposed on an upper surface of an insulating film and the lower electrode is fixedly disposed on an lower surface of the insulating film, thereby forming an integral electrode unit.

3. The passenger seat device as in claim 1, wherein:

the alternating current power source supplies an alternating voltage between the upper and the lower electrodes

4. The passenger seat device as in claim 1, wherein:

the alternating current power source includes a current-buffer circuit having a low output impedance for supplying to the lower electrode a potential following potential changes of the upper electrode.

5. The passenger seat device as in claim 1, wherein:

at least either one of the upper electrode or the lower electrode entirely covers the seat heater along a surface of the seat.

6. The passenger seat device as in claim 1, wherein:

the occupancy conditions include whether the seat is occupied or not and types of an occupant.

7. The passenger seat device as in claim 1, wherein:

the seat heater is also embedded in a seat-back of the seat.

8. A method of manufacturing a passenger seat for an automotive vehicle, the passenger seat having a seat heater embedded therein, an upper electrode embedded in the seat above the seat heater in parallel thereto, an alternating current power source for supplying alternating voltage having a predetermined frequency between the upper electrode and a member grounded to a vehicle body, and a detector for detecting occupancy conditions of the seat based on changes in a capacitance between the upper electrode and the member grounded to the vehicle body, the method comprising:

forming a heater-electrode unit integrally including at least the seat heater and the upper electrode, both being disposed in parallel to each other with an insulating layer disposed therebetween; and

embedding the heater-electrode unit in the passenger seat.

9. The method of manufacturing a passenger seat as in claim 8, wherein:

a wire harness including wires connecting the upper electrode to the alternating current power source and to the detector and another wire harness including wires for supplying power to the seat heater are formed integrally at least at a portion of both wire harnesses.

10. The method of manufacturing a passenger seat as in claim 8, wherein:

wires for supplying power from an on-board battery to the seat heater are commonly used as wires for supplying power to the alternating current power source.