Pressure sensitive switch and seating detector having the same

• US 6,450,046 B1
• Filed: 10/20/2000
• Issued: 09/17/2002
• Est. Priority Date: 10/22/1999
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Maeda, Tsutomu
• Primary Examiner(s): NOORI, MAX H
• Application Number:
  US09/693,142
• Time in Patent Office: 697 Days
• Field of Search: 738/620.41, 738/620.42, 738/620.43, 738/620.44, 738/620.45, 738/620.46, 738/624.51, 738/624.73
• US Class Current: 73/862.473
• 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 21/01532 using electric or capacitive field sensors
• 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
• CPC Class Codes: G01L 1/20 by measuring variations in ohmic resistance of solid materials or of electrically-conductive fluids of piezo-resistive materials G01L1/18; by making use of electrokinetic cells, i.e. liquid-containing cells wherein an electrical potential is produced or varied upon the application of stress

Abstract

A pressure sensitive switch disposed in the seat of a vehicle and a seating detector having the pressure sensitive switch are provided. Loss in its production can be reduced for obtaining an inexpensive pressure sensitive switch. The pressure sensitive has a movable contact layer formed underneath a top sheet and a fixed contact layer formed over a bottom sheet. A mark showing the resistance characteristic of the contact layer in the pressure sensitive switch is indicated on the top surface of the top sheet.

Claims

1. A pressure sensitive switch comprising:

a top sheet made of flexible insulating film;

a movable contact layer made of resin with conductive powder dispersed therein underneath said top sheet;

a bottom sheet made of flexible insulating film under said top sheet;

a fixed-contact layer made of resin with conductive powder dispersed therein over said bottom sheet;

an insulating spacer layer formed between said top sheet and said bottom sheet; and

a mark over at least one of said top sheet and said bottom sheet, said mark showing a contact resistance characteristic between said movable contact layer and said fixed contact layer.

2. A pressure sensitive switch comprising:

a top sheet made of flexible insulating film;

a movable contact layer made of resin with conductive powder dispersed therein underneath said top sheet;

a bottom sheet made of flexible insulating film under said top sheet;

a fixed-contact layer made of resin with conductive powder dispersed therein over said bottom sheet;

an insulating spacer layer formed between said top sheet and said bottom sheet; and

a wiring layer over one of said top sheet and said bottom sheet, said wiring layer being changed in a conducting condition corresponding to a contact resistance characteristics between said movable contact layer and said fixed contact layer.

3. The pressure sensitive switch as defined in claim 2, wherein an opening-hole is formed at a position on other of the one of said top sheet and said bottom sheet, the position opposing said wiring layer.

4. The pressure sensitive switch comprising:

a top sheet made of flexible insulating film;

a movable contact layer made of resin with conductive powder dispersed therein underneath said top sheet;

a bottom sheet made of flexible insulating film under said top sheet;

a fixed-contact layer made of resin with conductive powder dispersed therein over said bottom sheet;

an insulating spacer layer formed between said top sheet and said bottom sheet; and

a resistance layer over one of said top sheet and said bottom sheet, said resistance layer being changed in a resistance corresponding to a contact resistance characteristic between said movable contact layer and said fixed contact layer.

5. The pressure sensitive switch as defined in claim 4, wherein an opening-hole is formed at a position on other of the one of said top sheet and said bottom sheet, the position opposing said resistance layer.

6. A seating detector comprising:

a pressure sensitive switch including;

a top sheet made of flexible insulating film;

a movable contact layer made of resin with conductive powder dispersed therein underneath said top sheet;

a bottom sheet made of flexible insulating film disposed under said top sheet;

a fixed contact layer made of resin with conductive powder dispersed therein over said bottom sheet;

an insulating spacer layer disposed between said top sheet and said bottom sheet; and

a mark over at least one of said top sheet and said bottom sheet, said mark showing a contact resistance characteristic between said movable contact layer and said fixed contact layer; and

a control circuit coupled to said pressure sensitive switch,

wherein a predetermined threshold voltage in said control circuit is corrected corresponding to the contact resistance characteristic by selecting one of a plurality of resistors disposed in said control circuit.

7. A seating detector comprising:

a pressure sensitive switch including;

a top sheet made of flexible insulating film;

a movable contact layer made of resin with conductive powder dispersed therein underneath said top sheet;

a bottom sheet made of flexible insulating film disposed under said top sheet;

a fixed contact layer made of resin with conductive powder dispersed therein over said bottom sheet;

an insulating spacer layer disposed between said top sheet and said bottom sheet; and

a wiring layer over one of said top sheet and said bottom sheet, said wiring layer being changed in a conducting condition corresponding to a contact resistance characteristic between said movable contact layer and said fixed contact layer; and

a control circuit coupled to said pressure sensitive switch and detecting the contact resistance characteristic with the conducting condition,

wherein a threshold voltage in said control circuit is corrected corresponding to the contact resistance characteristic.

8. A seating detector comprising:

a pressure sensitive switch including;

a top sheet made of flexible insulating film;

a movable contact layer made of resin with conductive powder dispersed therein underneath said top sheet;

a bottom sheet made of flexible insulating film disposed under said top sheet;

a fixed contact layer made of resin with conductive powder dispersed therein over said bottom sheet;

an insulating spacer layer disposed between said top sheet and said bottom sheet; and

a resistance layer over one of said top sheet and said bottom sheet, said resistance layer being changed in a resistance corresponding to a contact resistance characteristic between said movable contact layer and said fixed contact layer; and

a control circuit coupled to said pressure sensitive switch, determining the contact resistance characteristic from the resistance,

wherein a threshold voltage in said control circuit is corrected corresponding to the contact resistance characteristic.