JPH10147207A - Occupant detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily discriminate an object and a human being without increasing circuit scale by receiving infrared ray from the symmetrical location of a seat, judging whether an object exists on the seat or not by detecting displacement of the object and outputting an operation control signal by judging whether the object on the seat is a human being or a stationary object. SOLUTION: First and second infrared ray sensors 8 and 9 are fitted on the inside of an installment panel, infrared ray is emitted to the symmetrical location of a backrest part and reflected light is detected. A pyroelectric infrared ray sensor 10 receives infrared ray of a front-seat passenger's seat by a light receiving lens surface and it is shown that an object on the front passenger's seat is a stationary object by outputting voltage when emitted light quantity of infrared ray does not change. When received light quantity exists, output voltage is changed by judging the object to be a human being. An occupant seating judgment circuit 12 judges the seating of the occupant of the front passenger s seat by receiving detection signals from the first infrared ray sensor 8, the second infrared ray sensor 9 and the pyroelectric infrared sensor 10. Thus, a human being and a stationary object are discriminated and circuit scale can be reduced.

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 for detecting whether or not an occupant is sitting in a passenger seat of a vehicle.

[0002]

2. Description of the Related Art As a conventional occupant detection device, for example, a device in which a pressure sensor is incorporated in a seat as disclosed in Japanese Utility Model Laid-Open Publication No. 1-130857, or a Japanese Patent Publication No. 7-78.
As disclosed in Japanese Patent No. 539, a plurality of electrodes are arranged on and around a seat to measure the capacitance between the electrodes. Whether or not it is used in the device will be described below.

That is, in the occupant protection system shown in FIG. 6, the acceleration at the time of collision is detected by the acceleration sensor 1, and the signal processing circuit 2 determines whether or not a serious collision is based on the acceleration signal. If it is determined that a serious collision has occurred, the driver's seat squib 4 is driven by the ignition via the first drive circuit 3, and the airbag for protecting the driver is deployed. At the same time, whether or not an occupant is seated in the passenger seat is detected by the occupant detection device 13 having the same function as the above occupant detection device, and the normally open switch circuit 5 is turned on based on the detection signal. As a result, the signal processing circuit 2 drives the squib 7 for the front passenger's seat through the second drive circuit 6, and when the occupant detection device 13 determines that the occupant is not seated on the front passenger's seat, the switch circuit 5 is activated. Is turned off, the passenger seat squib 7 is not driven by ignition.

[0004]

However, in such a conventional occupant detection device, for example, one in which a pressure sensor is built in a seat, every time the occupant is seated, the occupant is also subject to the vertical vibration of the occupant during traveling. Since the bending stress repeatedly acts on the sheet, the sheet is apt to be damaged quickly, causing disconnection, etc., and the appearance is not good. Further, since it is detected by the load, it is difficult to distinguish an object from a person. .

In a configuration in which a plurality of electrodes are arranged on and around a sheet and the capacitance between the electrodes is measured, the value of the capacitance formed by the electrodes is small.
Even if a person enters between the electrodes, the capacitance does not change significantly. For this reason, signal processing cannot be facilitated without increasing the area of the electrodes. As a result, a problem that the size of the electrodes is increased occurs. There is a problem that it is difficult to distinguish from

The present invention has been made in view of such a problem, and has as its object to propose an apparatus which does not increase the scale of a circuit or the like and can easily distinguish an object from a person.

[0007]

According to a first aspect of the invention, a pair of occupant detection devices are provided toward a symmetric position of a center line of a seat and receive infrared rays from the symmetric position of the seat. A distance sensor, a pyroelectric infrared sensor for detecting displacement of the object on the seat, and determining whether or not there is an object on the seat based on outputs from the pair of distance measurement sensors; Determine whether the object on the seat is human or stationary based on the sensor output from the electric infrared sensor,
A decision circuit for outputting an operation control signal.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Hereinafter, a first embodiment of the occupant detection device of the present invention will be described in the description of the configuration of the occupant protection device shown in FIG. In FIG. 1, components having the same configuration as that already described in FIG. 6 or equivalent components are denoted by the same reference numerals, and redundant description will be omitted. That is, in FIG.
Reference numerals 9 and 9 denote first and second infrared sensors (distance measuring sensors) each formed of a pair of an infrared light emitting element and an infrared light receiving element, and the instrument panel 1 in front of a passenger seat.
The first and second infrared sensors 8 and 9 are attached to the inside of the instrument panel 14 through small holes (not shown) provided in the instrument panel 14.
Below the backrest 15a, ie, the backrest 1
Infrared light is emitted from the infrared light emitting element to the left and right symmetrical positions A and B on the side of the seating portion 15b of the 5a (based on the center line L0 indicated by the broken line in FIG. 3), and the reflected light from the points A and B Is detected by the infrared light receiving element.

Reference numeral 10 denotes the first and second infrared sensors 8,
9, a pyroelectric infrared sensor mounted at substantially the same position as the pyroelectric infrared sensor 10. The pyroelectric infrared sensor 10 has a light-receiving lens surface divided into a plurality of sections, and a convex lens is formed for each section. A light-receiving element for receiving the reflected light condensed by the lens is built-in, and infrared rays from a plurality of points A to F over the entire passenger seat 15 are received on each of the light-receiving lens surfaces, and each point is received. If there is no change in the amount of emitted infrared light in A to F, a constant voltage is output to indicate that the object on the passenger seat is merely an object (stationary object) such as luggage. If there is a change in the amount of received light, it is determined that the object is a moving object, that is, a human, and the output voltage is changed. That is, although there is a difference in size in time with respect to time, a person always moves a part of the body, so that the pyroelectric infrared sensor 10 receiving infrared rays generated by a person receives infrared rays from a person. Utilizes the fact that the amount of infrared light emitted from each part of the human body is different, so that the amount of light incident on each convex lens on the light receiving lens surface is different, and the output changes over time. The pyroelectric infrared sensor 10
When schematically described, detection areas of respective light receiving surfaces are set as shown by oblique lines in FIG. 5, for example, and infrared rays from those detection areas are detected.

Reference numeral 11 denotes a front / rear position sensor for the front passenger seat.
The position when the front end 5 is moved forward to the maximum is defined as a reference position X, and a value proportional to the movement distances S1 and S2 of the passenger seat 15 from the reference position X to the rear of the vehicle is determined as a movement amount by a slide resistance or the like. To detect. An occupant seat determination circuit 12 receives detection outputs from the first infrared sensor 8, the second infrared sensor 9, the pyroelectric infrared sensor 10, and the front / rear position sensor 11 for the occupant to sit on the passenger seat 15. It is determined whether or not.

Next, the determination algorithm in the occupant seating position determination circuit 12 will be described with reference to the flowchart shown in FIG. That is, the occupant seat determination circuit 12
When the power is turned on, the process proceeds from step 100 to step 110, in which the respective infrared light emitting elements of the first and second infrared sensors 8 and 9 provided on the instrument panel 14 are driven to emit infrared light from the respective infrared light emitting elements. Is emitted toward the symmetrical positions A and B about the center line L0 of the passenger seat 15, and in the next step 120, the reflected light from the points A and B is received by the respective infrared light receiving elements. In step 130, the first and second infrared sensors are calculated by calculating the time from when the infrared light is emitted toward the backrest 15a of the passenger seat 15 in step 110 until the reflected light is received in step 120. The distances L1, L2 between 8, 9 and the points A, B of the passenger seat 15 are measured.

Next, in step 140, based on the reference position X of the passenger seat 15 as a reference, how much the passenger seat 15 is moved from the reference position X toward the rear of the vehicle is determined by a front-rear position of the passenger seat including a slide resistance and the like. The signal detected by the sensor 11 is input to the occupant seating position determination circuit 12, and the process proceeds to step 150. In step 150, it is determined whether or not the following three conditions are satisfied. If any one is satisfied, the process proceeds to step 160. That is, the satisfaction condition is that the left and right distances L1 and L2 from the first and second infrared sensors 8 and 9 detected in step 130 to the points A and B of the backrest 15a of the passenger seat 15 are substantially the same. This is the case when it is determined that they are equal.
The seat position S of the passenger seat 15 detected in step S4 is the seat position S in FIG.
If it is determined that the value is smaller than the reference value S0 as in the case of 1, the passenger seat 1
5 is a case where it is determined that there is a high possibility that no luggage is placed or nothing is placed, and thirdly, a passenger seat 15 is mounted on the passenger seat 15 in order to mount a child seat.
Is shifted as far forward as possible and the seat position S is approaching the reference position X.

Therefore, in step 150, step 1
If it is determined that the left and right distances L1 and L2 from the first and second infrared sensors 8 and 9 detected at 30 to the points A and B of the backrest 15a of the passenger seat 15 are different, the assistant detected at step 140 When it is determined that the seat position S of the seat 15 is shifted rearward as shown by the reference numeral S2 and is larger than the reference value S0, it is determined that there is a high possibility that a human is sitting on the passenger seat 15 and step 180 is performed. Proceed to.

In step 160, the first and second infrared sensors 8, 9 detect points A, A on the backrest 15 a of the passenger seat 15.
It is determined whether the detection distances L1 and L2 to B have changed over time, and if it is determined that no change has occurred over time, that is, it can be asserted that no human is sitting on the passenger seat 15. Therefore, the routine proceeds to step 170, in which the switch circuit 5 in FIG. 1 is switched to the off state, so that the squib 7 for the passenger seat is not ignited. On the other hand, if it is determined in step 160 that the detection distances L1 and L2 have changed with time and there is a possibility that a human is sitting, the process proceeds to step 180.

In step 180, the occupant seat determination circuit 1
2 receives the supply of the infrared light receiving signal from the pyroelectric infrared sensor 10, and in step 190, determines whether or not the received infrared light reception amount changes with time, and determines that there is no change with time. Then, the process proceeds to step 170, and if it is determined that there is a change, the process proceeds to step 200, and the switch circuit 5 is switched to the ON state. That is, the passenger seat 15
If it is determined that a human is seated on the vehicle, the occupant must be protected in the event of a collision, so that the supply of the ignition current to the squib 7 for the passenger seat is permitted and the deployment of the airbag is permitted.

[0016]

According to the present invention, it is possible to easily distinguish a person from a stationary object such as luggage and to provide an apparatus having a small circuit scale.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing a first embodiment of the present invention.

FIG. 2 is a flowchart explanatory diagram of an occupant seat determination circuit of FIG. 1;

FIG. 3 is an explanatory diagram showing a positional relationship between detection points of first and second infrared sensors and a passenger seat.

FIG. 4 is an explanatory diagram showing a relationship between detection points of first and second infrared sensors and a front-rear position of a passenger seat.

FIG. 5 is an explanatory diagram showing a relationship between a detection area of a pyroelectric infrared sensor and a passenger seat.

FIG. 6 is a circuit block diagram of a conventional occupant protection device using an occupant detection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Acceleration sensor 2 Signal processing circuit 4, 7 Squib 5 Switch circuit 8, 9 Infrared sensor (ranging sensor) 10 Pyroelectric infrared sensor 11 Passenger seat front-back position sensor 12 Occupant seating judgment circuit

Claims (1)

[Claims] 1. A distance measuring sensor provided in a pair toward a symmetric position of a center line of a seat and receiving infrared rays from the symmetric position of the seat, and a pyroelectric sensor for detecting displacement of an object on the seat. Type infrared sensor, and determines whether or not there is an object on the seat based on the output from the pair of distance measurement sensors, and detects the object on the seat based on the sensor output from the pyroelectric infrared sensor. Is a human or a stationary object,
An occupant detection device, comprising: a disconnection circuit that outputs an operation control signal.