Load sensor, method of detecting load and pedestrian protection system

• US 20060091299A1
• Filed: 10/28/2005
• Published: 05/04/2006
• Est. Priority Date: 10/28/2004
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Iyoda, Motomi, Takahashi, Hiroyuki, Miyata, Yujiro, Kachu, Ryotaro, Inamoto, Takashi, Ohtaka, Koji
• Granted Patent: US 7,456,382 B2
• Time in Patent Office: Days
• US Class Current: 250/221
• CPC Class Codes: B60R 2021/01068 between different sensors and airbag control unit
• CPC Class Codes: B60R 2021/01095 optical
• CPC Class Codes: B60R 21/0136 responsive to actual contact with an obstacle , e.g. to vehicle deformation, bumper displacement or bumper velocity relative to the vehicle monitoring crash strength in combination with passenger seat detection B60R21/01558
• CPC Class Codes: B60R 21/36 using airbags

Abstract

A load sensor includes a optical fiber sensor that provides output analog signals in response to shocks of various magnitudes caused by hits by a vehicle on various objects, two or more amplifiers each of which approximates a non linear function of the analog signals and a unit that converts the linear functions into digital data. Therefore, each analog signal either in a lower magnitude range or a higher magnitude range can be amplified by one of the amplifiers that has a more suitable gain, so that the magnitude of the shock can be accurately converted into digital data for a pedestrian protection airbag system.

Claims

1. A load sensor comprising:

first means for providing one of output signals in response to a shock caused by a hit on an object;

second means for providing a plurality of linear functions by approximating various output analog signals of said first means corresponding to shocks of various magnitudes; and

third means for providing digital data that correspond to the one of output signals caused by the hit on an object from one of the linear functions.

2. The load sensor according to claim 1, wherein said second means comprises a plurality of amplifiers each of which has a prescribed gain.

3. The load sensor according to claim 1, wherein said first means comprises a light emitting element, an light sensing element and an optical fiber connecting said light emitting element and said light sensing element and fourth means for deforming said optical fiber in response to the shocks.

4. A pedestrian protection system comprising:

the load sensor according to claim 1;

an object examining unit for providing an output signal when discriminating a pedestrian according to the digital data; and

an air bag control unit for providing an airbag operating signal when receiving the output signal from said object examining unit.

5. The pedestrian protection system according to claim 4, wherein said second means comprises a plurality of amplifiers each of which has a prescribed gain.

6. The pedestrian protection system according to claim 5, wherein said second means comprises a lower load amplifier and a higher load amplifier.

7. The pedestrian protection system according to claim 5, further comprising a single communication line for sending the digital data from said third means to said airbag control unit.

8. A method of detecting a load caused by hitting an object comprising:

a first step of providing output analog signals in response to shocks caused by hits of various magnitudes;

a second step of approximating the output analog signals by a plurality of linear functions; and

a third step of providing digital data converted from one of the linear functions that corresponds to one of the output analog signals that is caused by hitting the object.