Device to detect seat belt buckle status

• US 6,079,744 A
• Filed: 04/24/1998
• Issued: 06/27/2000
• Est. Priority Date: 04/24/1998
• Status: Expired due to Fees

• Current Assignee: Key Safety Systems, Inc. (Ningbo Junsheng Investment Group Co., Ltd.)
• Original Assignee: Breed Automotive Technology, Inc. (Ningbo Junsheng Investment Group Co., Ltd.)
• Inventors: Patel, Vihang C., Patel, Ashok F., Husby, Harald Snorre
• Primary Examiner(s): Dickson, Paul N.
• Application Number:
  US09/065,684
• Time in Patent Office: 795 Days
• Field of Search: 280/801.1, 180/268, 180/270, 24/303, 24/633
• US Class Current: 280/801.1
• CPC Class Codes: B60R 2022/4816 for sensing locking of buckle
• CPC Class Codes: B60R 22/48 Control systems, alarms, or interlock systems, for the correct application of the belt or harness
• CPC Class Codes: G01D 5/147 influenced by the movement of a third element, the position of Hall device and the source of magnetic field being fixed in respect to each other
• CPC Class Codes: Y10T 24/45623 and operator therefor

Abstract

A seat belt buckle and latch indicating system employs a seat belt buckle with a Giant Magnetoresistive (GMR) sensor spaced from a magnet above a gap through which a ferromagnetic latch protrudes. The latch may reside at three distinct positions: unlatched, latched, and latched without the presence of a hasp. The latch functions as a magnetic field concentrator with the result that the sensed magnetic field is dependent on latch position. The GMR sensor provides a signal indicating the sensor is working at all times, and provides specific information based on physical positioning of the critical components of the belt and which indicates that the buckle is mated to the seat belt hasp.

Claims

1. A seat belt buckle and latch indicator sensor comprising:

a seat belt buckle;

a flexible seat belt;

a seat belt hasp connected to the seat belt, the hasp fitting within the seat belt buckle to releasably connect the seat belt to the buckle;

a latch formed of ferromagnetic material mounted within the seat belt buckle, the latch being movable between an unlatched position a latched position in which the seat belt hasp is mechanically retained within the seat belt buckle, and a latched-without-a-hasp-present position;

a magnetic field sensor fixedly mounted to the seat belt buckle; and

a magnet having a magnetic field, the magnet being spaced from the magnetic field sensor and fixedly mounted to the seat belt buckle, the magnet and the sensor defining a gap therebetween, wherein the movement of the latch between the unlatched position, the latched position, and the latched-without-a-hasp position is such that the magnetic field sensed by the sensor changes.

2. The seat belt buckle and latch indicator of claim 1 wherein the latched position is closer to the gap than the unlatched position, and the latched-without-a-hasp position is closer to the gap than the latched position.

3. The seat belt buckle and latch indicator of claim 1 wherein the magnetic field sensor is a Giant Magnetoresistive sensor.

4. The seat belt buckle and latch indicator of claim 1 further comprising a ferromagnetic body, the body forming a hole for attaching the seat belt to a vehicle, the body forming an opening through which the latch moves, wherein the magnetic field sensor is positioned on one side of the opening through which the latch moves and the magnet is positioned on an opposite side so that the opening defines the gap between the sensor and the magnet.

5. The seat belt buckle and latch indicator of claim 1 further comprising a ferromagnetic body, the body forming a hole for attaching the seat belt to a vehicle, the body forming an opening through which the latch moves, and wherein the body also forms an opening through the body and positioned to overlie the seat belt hasp when the hasp is within the seat belt buckle, wherein the magnetic field sensor is mounted through the opening adjacent the hasp, and wherein the magnet which is spaced from the magnetic field sensor is also mounted through the opening adjacent the hasp.

6. The seat belt buckle and latch indicator of claim 1 wherein the magnetic sensor and magnet are positioned so that movement of the latch between the unlatched position and the latched position moves a portion of the latch away from the gap such that latching of the seat belt buckle decreases the magnetic field sensed by the sensor.

7. A seat belt buckle and latch indicator comprising:

a seat belt buckle;

a seat belt;

a seat belt hasp connected to the seat belt, the hasp fitting within the seat belt buckle to join the seat belt to the buckle;

a latch formed of ferromagnetic material mounted within the seat belt buckle, the latch being movable wherein the latch is movable between three positions, an unlatched position, a latched position, wherein the seat belt hasp is mechanically retained within the seat belt buckle, and a latched-without-a-hasp-present position;

a magnetic field sensor fixedly mounted to the seat belt buckle;

a magnet having a magnetic field, the magnet being spaced from the magnetic field sensor and fixedly mounted to the seat belt buckle, wherein a gap is defined between the magnet and the sensor;

a means for changing the magnetic field at the sensor;

wherein the attributes of the magnetic field detected at the magnetic sensor is detectably different for each of said three latch positions.

8. The seat belt buckle and latch indicator of claim 7 wherein the magnetic field sensor is a Giant Magnetoresistive sensor.

9. The seat belt buckle and latch indicator of claim 7 further comprising a ferromagnetic body, the body having portions defining a hole for attaching the seat belt to a vehicle, wherein the body has portions defining an opening through which the latch moves, and wherein the magnetic field sensor is positioned on one side of the opening through which the latch moves and the magnet is positioned on an opposite side so the opening defines the gap between the sensor and the magnet.

10. A seat belt buckle and latch status detector comprising:

a seat belt;

a ferromagnetic latching member connected to the seat belt, the latching member having portions defining a latch hole;

a buckle having a body with spaced plates which receive portions of the latching member therein, the latching member extending downward into the buckle;

a latch which is supported on the buckle body for displacement transverse to the latching member, the latch being movable between an unlatched position spaced from a body first plate and a latched position in which portions of the latch extend through the latch hole and through a slot in the first plate, the latch comprising a protuding nose which extends at least partially through the slot in the latched position and a face on either side of the nose which engage against the latching member in the latched position to restrain the transverse displacement of the latch, such that the nose protrudes to a greater extent through the slot when in a latched position with the latching member absent than when the latching member is present, and wherein the sensor is thereby able to detect a difference in magnetic field between a state in which the latching member is engaged within the buckle in a latched condition and a latched condition in which the latching member is not present in the buckle body;

a spring connected to the buckle body which urges the latch toward the latching member;

a magnet mounted to the buckle body in proximity to the slot through which the latch extends in the latched position; and

a magnetic field sensor mounted to the seat belt buckle spaced from the magnet, such that a gap is defined between the sensor and the magnet into which portions of the latch extend in the latched position, such that the magnetic field detected by the sensor is different in the latch latched and unlatched positions, such that latching of the seat belt buckle changes the magnetic field detected by the sensor.

11. The seat belt buckle and latch status detector of claim 10 wherein the magnetic field sensor is a Giant Magnetoresistive sensor.

12. A seat belt buckle and latch indicator sensor comprising:

a seat belt buckle, the seat belt buckle having a ferromagnetic body;

a latch formed of ferromagnetic material mounted within the seat belt buckle, the buckle body having portions defining an opening through which the latch moves, the latch being movable between an unlatched position and a latched position in which a seat belt hasp is mechanically retained within the seat belt buckle;

said buckle body having a sensor opening;

a magnetic field sensor fixedly mounted to the buckle within the sensor opening and positioned therein to overlie the seat belt hasp when the hasp is retained within the seat belt buckle; and

a magnet having a magnetic field, the magnet being spaced from the magnetic field sensor and fixedly mounted to the buckle, the magnet being mounted within the sensor opening to overlie the hasp, the magnet being spaced from the sensor to define a gap therebetween, wherein movement of the latch between the unlatched position and the latched position is such that latching of the seat belt buckle changes the magnetic field sensed by the sensor.

13. The seat belt buckle and latch indicator of claim 12 wherein the presence of the hasp changes the magnetic field sensed by the sensor.

14. The seat belt buckle and latch indicator of claim 12 wherein the magnetic field sensor is a Giant Magnetoresistive sensor.