JPH10129418A - Crew detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To judge whether an object existing on a seat is a human being or a stationary substance without providing a sensor in the seat and regardless of seat being a sliding or a reclining type. SOLUTION: An infrared ray emission element 3 and an infrared ray receiving element 1 are provided on a seat belt 10 buckle 11 with the receiving surface and the emission surface facing toward the seat. Also provided herewith is a judging means judging that the object on the seat is a static substance when the magnitude of an output signal from the infrared ray receiving element 1 is of a specific level and its variation is below the reference value, that the object on the seat is a human being when the manitude of the output signal is of more than the specific level and its variation is the reference value or more, and that no object exists on the seat when the magnitude of the output signal is below the prescribed level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an occupant detection device effective for an occupant restraint device such as an airbag for protecting an occupant in the event of a vehicle collision.

[0002]

2. Description of the Related Art First, an occupant detection device according to the present invention will be described. That is, Japanese Utility Model Laid-Open No. 1-130857 discloses a system in which a sheet-shaped pressure sensor is incorporated in a seat, and the resistance is changed by adding the weight of an occupant, and the system is disclosed in Japanese Patent Publication No. 7-78539. Has a pair of electrodes placed on the floor side and ceiling side of the car body of the seat with the seat interposed,
There is a method of detecting whether or not an occupant is seated on a seat by detecting a change in capacitance due to a change in dielectric constant between the electrodes. Further, Japanese Unexamined Patent Publication No.
In the -19609, an infrared sensor is installed near the glove box in front of the passenger seat, emits infrared rays at a predetermined radiation angle in the seat direction, calculates a distance between the vehicle and a reflector on the seat, There has been a method of distinguishing between a human and a stationary object from a detection distance.

[0003]

However, among the various types of sensors described above, those in which a sheet-shaped pressure sensor is inserted into a seat, those in which the sheet material of the pressure sensor is rigid and not pliable, include There is a problem that it is difficult to secure a comfortable sitting feeling because there is a feeling that foreign matter is contained in the inside.

[0004] Further, since stress strain is applied to the sheet-shaped pressure sensor every time a person moves when the person sits down, it is difficult to ensure mechanical durability.
In addition, since the material of the seat skin may differ depending on the vehicle, in that case, there is a problem that a pressure sensor having sensitivity characteristics according to the material of the seat skin is required. Furthermore, this pressure sensor has a problem that it is impossible to distinguish between a human and a stationary object.

Further, in the case where the infrared sensor is installed near the glove box, when the seat is slid or reclined due to a large infrared radiation angle, the sliding amount and The detection distance had to be corrected according to the reclining amount.

Therefore, the present invention has been made in view of the above-mentioned problems, and there is a case where a sensor is not provided in a seat, and the sensor exists in a seat regardless of sliding and reclining of the seat. It is an object of the present invention to provide a device that can determine whether the object is a stationary object.

[0007]

An occupant detection device according to the present invention is provided with an infrared light emitting element and an infrared light receiving element on a buckle portion of a seat belt with their light receiving surface and light emitting surface facing the seat. When the magnitude of the output signal from the infrared light receiving element is within a predetermined range, and when the level fluctuation is equal to or less than a reference value, the object existing in the seat is determined to be a stationary object, and the magnitude of the output signal is within a predetermined range. Above,
When the level change is equal to or more than a reference value, a judgment means for judging that there is nothing in the seat as a human, and further, when the magnitude of the output signal is equal to or less than a predetermined range, judges that there is nothing in the seat. It is provided.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. First Embodiment A first embodiment of the present invention will be described with reference to FIGS. 1 to 6, and the description will be made using an occupant restraint device for a passenger seat. That is, reference numeral 1 denotes an infrared light receiving element, which is attached to, for example, a buckle 11 of a passenger seat belt 10 together with an infrared light emitting element 3 described later. Reference numeral 2 denotes a seat determination circuit which receives an infrared light receiving signal from the infrared light receiving element 1 and a control circuit 6 which will be described later.
A drive signal supplied to the infrared light emitting element 3 is input as a timing signal for emitting infrared light, a time required from light emission to light reception is detected based on the timing signal, and a passenger seat is detected based on the detected time. The distance to the reflective object existing on the seat is calculated, and based on the distance, it is determined whether a stationary object is present on the seat or a person is seated according to the flowchart shown in FIG. Is output to the control circuit 6. The details of the flowchart of FIG. 2 will be described later.

Next, reference numeral 3 denotes an infrared light emitting element, which is supplied with a drive signal having a constant period from a control circuit 6 described later and emits infrared rays based on the drive signal. Reference numeral 4 denotes an acceleration sensor which detects an acceleration generated at the time of a vehicle collision and outputs a signal corresponding to the acceleration. Reference numeral 5 denotes a collision determination circuit, which determines whether the collision is a serious collision or a light collision based on the acceleration signal supplied from the acceleration sensor 4, and indicates a serious collision to a control circuit 6 described later only when the collision is determined to be a serious collision. Supply signal.

Reference numeral 6 denotes a control circuit, which has a light emission control function, a judgment function, and a diagnosis function. First, as a judgment function, the seating judgment circuit 2 judges that a human is sitting on the passenger seat. Only when a signal indicating a serious collision is supplied from the collision judging circuit 5, a driving signal for igniting the squib is supplied to the airbag driving circuit 7 and the pretensioner driving circuit 8. . Next, as a light emission control function, a drive signal of a constant cycle is supplied to the infrared light emitting element 3, and the drive signal is transmitted from the infrared light emitting element 4 to the seat determination circuit 2. Is supplied as a timing signal indicating that Next, the diagnostic function performs a failure diagnosis of each part of the occupant restraint device, and when a failure is detected, supplies a display signal of the content of the failure to the display 9 for display. The seat determination circuit 2, the collision determination circuit 5, and the control circuit 6
Since it is constituted by a microcomputer, only the parts related to the present invention will be described below according to the flowchart shown in FIG.

That is, when the power is turned on, the process proceeds to step 100, in which the control circuit 6 generates and supplies a drive pulse, which is a drive signal, to the infrared light emitting element 3 at a constant cycle, and seats the infrared light in the passenger seat. It emits light toward the part where the waist of the human being is located. Next, the routine proceeds to step 110, where the emitted infrared reflected light is received by the infrared light receiving element 1. In step 120, the time from when the infrared light emitting element 3 emits light when the driving signal is supplied from the control circuit 6 to when the infrared light receiving element 1 receives the reflected light is measured, so that the buckle 11 of the seat belt 10 The distance to the object on the passenger seat is calculated, and the process proceeds to the next step 130. In step 130, every time the measured distance calculated by the seating determination circuit 2 is calculated at a constant period, the measured distance is averaged based on a plurality of signals calculated so far, and the average value and the range of change are shown. A predetermined number of items are stored in a time-series manner in a memory that is not used.

In step 140, the process proceeds to step 160 in which it is determined that the average value of the distance stored in the memory in step 130 is equal to or larger than a predetermined value, and it is determined that there is a stationary object on the passenger seat or that the seat is empty. The control circuit 6 stops outputting signals for driving the airbag drive circuit 7 and the pretensioner drive circuit 8. If it is determined in step 140 that the average value of the distances stored in the memory is equal to or smaller than the predetermined value, the process proceeds to step 150, and
If it is determined at 0 that the change width of the distance stored in the memory is equal to or smaller than a predetermined value, the routine proceeds to step 160, where it is determined that there is a stationary object on the passenger seat, and the airbag driving circuit 7 and the pretensioner The output of the signal for driving the drive circuit 8 is stopped, and the process returns to step 100.

Further, in step 150, the process proceeds to step 170 in which it is determined that the change width of the distance stored in the memory is equal to or greater than a predetermined value, and it is determined that a human is sitting on the passenger seat. Return to

Next, the infrared light emitting element 1 and the infrared light receiving element 3 in the above description of the structure will be described below. The infrared light emitting element 1 and the infrared light receiving element 3 are a passenger seat belt 10 fixed at one end to the floor of the vehicle.
Of the buckle 11 (see FIG. 3), and is always provided in the direction of the seat. Therefore, since the detection distance may be in the range of the seating portion of the seat, a short distance of 1 mm to 200 mm may be sufficient as shown in FIG. On the other hand, when the infrared light emitting element and the infrared light receiving element are provided near the glove box of the instrument panel as in the related art, the detection distance is as long as 80 mm to 1000 mm. If the light emission output is not increased, the magnitude of the reflected light is small, so that the signal processing becomes complicated or the signal processing amount increases. Note that reference numeral 12 in FIG.
Is a mounting hole provided in the buckle 11, and a fitting for mating is engaged and connected as required.

Next, the operation of the above configuration will be described.
When the control circuit 6 starts operating, it supplies a drive signal with a constant period to the infrared light emitting element 3 and supplies the drive signal to the seating determination circuit 2 as a timing signal of infrared light emission. Upon receiving the drive signal, the infrared light emitting element 3 emits light within the range of the solid angle shown by oblique lines in the perspective view of FIG. In addition, as shown in FIG. 6, the light is emitted with a spread of the angle θ in the vertical direction.

As a result, after receiving the timing signal, the seat determination circuit 2 receives the timing signal, and after receiving the timing signal, the infrared light receiving element 1 changes the reflected light from the object 22 existing in the seating portion 21 of the passenger seat 20. The time until the light is received is detected, and based on the detected time, the seat determination circuit 2
The distance from the infrared light emitting element 3 and the infrared light receiving element 1 to the object in the passenger seat and the change width of the detected distance are detected.

Based on the detected distance and the range of change of the distance, it is determined whether the object 22 present on the seat 21 of the passenger seat 20 is a stationary object such as luggage or a human. If it is determined that the seat is vacant, the seat determination circuit 2 supplies the control circuit 6 with a signal for suppressing the output. As a result, even if the control circuit 6 receives a judgment signal indicating a serious collision from the collision judgment circuit 5, the control circuit 6 does not output a drive signal to the airbag driving circuit 7 and the pretensioner driving circuit 8.

On the other hand, when it is determined that a person is sitting on the seat 21 of the front passenger seat 20 on the basis of the distance detected by the seat determination circuit 2 and the range of change in the distance, the control circuit 6 is inhibited. To release. As a result, when the control circuit 6 is supplied with a determination signal indicating a serious collision from the collision determination circuit 5, the control circuit 6 outputs a drive signal to the airbag drive circuit 7 and the pretensioner drive circuit 8.

[0019]

As described above, according to the present invention, it is possible to easily detect whether or not a person is sitting on a seat with weak infrared light, so that the power consumption of infrared light receiving and light emitting elements can be reduced. The effect of extending the life is exhibited.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of an occupant restraint system according to a first embodiment of the present invention.

FIG. 2 is a flowchart illustrating an algorithm for determining whether or not there is a human in a seat in FIG.

FIG. 3 is an explanatory diagram showing a state where an infrared light receiving element and a light emitting element are attached to a buckle of a seat belt.

FIG. 4 shows a relative light output /
FIG. 4 is a diagram for explaining distance characteristics.

FIG. 5 is an explanatory perspective view for explaining a detection range of an infrared light receiving element.

FIG. 6 is an explanatory sectional view for explaining a detection range of the infrared light receiving element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Infrared light receiving element 2 Seating judgment circuit 3 Infrared light emitting element 4 Acceleration sensor 5 Collision judgment circuit 6 Control circuit 7 Airbag drive circuit 8 Pretensioner drive circuit 10 Seat belt 11 Buckle

Claims (1)

[Claims] 1. An infrared light emitting element and an infrared light receiving element,
The light receiving surface and the light emitting surface are provided on the buckle portion of the seat belt facing the seat direction, and when the magnitude of the output signal from the infrared light receiving element is within a predetermined range and the level fluctuation is equal to or less than a reference value, An object existing in the seat is determined to be a stationary object, and when the magnitude of the output signal is equal to or higher than a predetermined range and the level variation is equal to or higher than a reference value, the object existing in the seat is determined to be a person, and the output signal is further determined. An occupant detection device provided with a determination means for determining that nothing is present in the seat when the size of the seat is equal to or less than a level within a predetermined range.