JPH1044923A - Occupant protective device for front passenger seat - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect an occupant in a front passenger seat and a child in a child seat by one unit by calculating the distance from a transmitter to an object on the front passenger seat, and detecting presence/absence of the object on the front passenger seat using the ultrasonic wave. SOLUTION: An ultrasonic element 11a for transmission and an ultrasonic element 11b for reception are provided in the vicinity of the globe box fitting position of a dashboard 10, and a circuit 12 to drive the ultrasonic element 11a for transmission and to process the detected signal from the ultrasonic element 11b for reception is connected thereto. A microcomputer 12e inputs the ultrasonic signal of reflection by the outputted pulse from an A/D converter 12d, and calculates the time required from the time point of feeding the signal to the ultrasonic element 11a for transmission to the time point when the reflected wave is received by the ultrasonic element 11b for reception, judges whether or not a child seat 5 is installed by comparing the calculated time with the reference value, and prohibits development of an air bag.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an occupant protection device for a front passenger seat which determines whether or not an occupant is in a passenger seat and activates the occupant protection device for a front passenger seat.

[0002]

2. Description of the Related Art A conventional passenger protection device for a passenger seat of this type will be described below. First, a case will be described in which it is determined whether or not an occupant is sitting in a passenger seat of a vehicle so that the airbag can be deployed or cannot be deployed or controlled.
That is, as shown in FIG. 6, a pressure sensor 2 such as a conductive rubber formed in a sheet shape is provided on a seat 1a of a passenger seat 1, and an occupant 3 sits on the sheet pressure sensor 2. When a load is applied, it is detected that the occupant 3 is sitting on the passenger seat 1. The detection signal from the pressure sensor 2 is supplied to an airbag deployment control circuit 4 mounted on the vehicle side to enable the deployment of the airbag in the event of an accident, and the detection signal from the pressure sensor 2 controls the deployment of the airbag. When the airbag is not supplied to the circuit 4, it is determined that the occupant 3 is not sitting on the passenger seat 1 and the airbag deployment is disabled.

[0003] Next, a description will be given of a control in a case where it is determined whether or not a child seat, that is, a so-called child seat 5 is placed on the passenger seat 1 to enable or disable the deployment of the airbag. I do. That is, FIG.
As shown in (1), the child seat 5 includes an antenna, a power supply circuit that receives and accumulates power transmitted by an electromagnetic wave by the antenna, and a transmission circuit that is fed from the power supply circuit and outputs a unique code from the antenna as an electromagnetic wave. Tag IC
7 is buried, an antenna 8 is buried in the seat 1a of the passenger seat 1, and power is supplied to the tag IC 7 by supplying a power AC signal from the control circuit 6 to the antenna 8 buried in the seat 1a. Thereafter, the antenna 8 receives a unique code supplied by an electromagnetic wave from the tag IC 7, and when the control circuit 6 receives the unique code, controls the airbag to be undeployable, and otherwise controls the airbag to be deployable.

[0004]

However, in the above-described occupant protection device for a passenger seat, an occupant detection function for detecting whether or not an occupant is present in the passenger seat and a detection of whether or not a child seat is attached. However, since these functions are separate devices (units), there is a problem in that if both devices are to be installed, the cost increases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to enable one unit to detect a passenger in a passenger seat and a child seat.

[0006]

According to a first aspect of the present invention, there is provided an occupant protection system for a passenger seat, which is installed in front of a passenger seat and continuously emits ultrasonic waves toward the passenger seat for a first predetermined time. And a second state continuously outputting for a second predetermined time shorter than the first predetermined time, and outputting from the second state to the first state. An ultrasonic transmitter that is in a non-output state when moving to an ultrasonic receiver that receives an ultrasonic wave output from the ultrasonic transmitter and reflected by an object on the passenger seat, and from the ultrasonic transmitter A distance calculation unit that calculates a distance from the ultrasonic transmitter to an object on a passenger seat based on the reception timing of the ultrasonic receiver based on the output of the ultrasonic waves caused by the intermittent output of the ultrasonic waves. And the ratio of the fluctuation of the envelope of the ultrasonic wave output from the ultrasonic receiver to a reference value. An object detection unit that detects the presence or absence of an object on the passenger seat, and compares the distance calculated by the distance calculation unit with a reference value.When the distance is smaller than the reference value, an airbag deployment non-permission signal is output. And an airbag deployment control circuit for outputting the airbag deployment permission signal in response to the detection signal from the object detection unit.

In a second aspect of the present invention, the object detector calculates a voltage difference and a time between characteristic points of a waveform of an envelope of the received ultrasonic wave, and when the voltage difference and the time exceed a reference value. It is characterized in that it is determined that there is an occupant in the passenger seat.

[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. In FIG. 1, FIG. 6 and FIG.
The same reference numerals are given to the same or equivalent components described in the above, and the description thereof is omitted, and only different portions will be described below. That is, reference numeral 10 denotes a dashboard (instrument panel) of the vehicle, and the transmitting ultrasonic element 1 is located near the glove box mounting position.
1a and a receiving ultrasonic element 11b are provided, and the driving and receiving ultrasonic element 11b of the transmitting ultrasonic element 11a are provided.
A circuit 12 for signal processing of the detection signal from is connected.

Next, the circuit 12 will be described with reference to FIG. A drive circuit 12a outputs a plurality of pulses (for example, a pulse of 40 Hz for 1 ms) from the transmitting ultrasonic element 11a based on a pulse signal intermittently supplied from a microcomputer 12e described later. The transmitting ultrasonic element 11a is driven at a constant frequency, that is, intermittently, and based on a pulse of a constant frequency, for example, 40 KHz (FIG. 3A) continuously supplied from the microcomputer 12e. Output an ultrasonic signal. This intermittent drive is performed when the ignition switch is turned on, and then the pattern of continuous drive is repeated. 12b is a band-pass filter with an amplification function for extracting and amplifying an output signal from the receiving ultrasonic element 11b, and 12c detects an output from the band-pass filter 12b and outputs an A / D converter 12d.
Detection circuit that outputs to

Reference numeral 12e denotes a microcomputer which, when the ignition switch is turned on to turn on the power to the drive circuit 12a, turns on a set of plural pulses at regular intervals and continuously outputs pulse signals. Supply to
Repeat thereafter. Further, the microcomputer 12e outputs a set of a plurality of pulses at regular intervals,
An ultrasonic signal reflected by the pulse is input from the A / D converter 12d, and from the time when a set of plural pulses is supplied to the transmitting ultrasonic element 11a, the reflected wave is changed to the receiving ultrasonic element 11b. Is calculated by the microcomputer 12e, the distance to the obstacle in front is calculated based on the calculated time, and the distance signal is compared with a reference value to determine whether the child seat 5 is installed. It is determined whether the child seat 5 has been installed if the calculated distance is smaller than the reference distance. To disallow the deployment of an airbag (not shown).

The microcomputer 12e continuously outputs a pulse to the drive circuit 12a, and outputs an ultrasonic reflected wave corresponding to the pulse to the A / D converter 12d.
If you are input, the magnitude of the fluctuation width v ₁ between adjacent poles of the waveform of the input signal is greater than a predetermined value v _X in from
When the time t ₁ between the adjacent poles is equal to or less than a predetermined value t _x, it is determined that the occupant 3 is seated, and the airbag can be deployed.

Next, an outline of the operation of the above configuration will be described with reference to FIG. That is, when power is supplied to the circuit, the microcomputer 12e is ready to output a pulse of a constant frequency, for example, 40 KHz, to the drive circuit 12a as shown in FIG. As a set, the first mode (first state) in which the transmitting ultrasonic element 11a is continuously driven for 10 ms, and 10 m
When switching from the first mode to the second mode alternately with the second mode (second state) of continuously driving for a predetermined time longer than s, the output is maintained at the zero level for, for example, 10 ms. Then, the process is repeated so that the distance can be calculated. A signal output from the transmitting ultrasonic element 11a, reflected and received by the receiving ultrasonic element 11b is extracted by the band-pass filter 12b (for example, when the reflecting object is a fixed object, FIG. 3B). (D), when the reflecting object is a moving object such as a human, the waveform shown in FIG. 3 (D) fluctuates, and furthermore, in the detection circuit 12c (when the reflecting object is a fixed object, FIG. 3 (C)
(E) outputs a constant voltage having an amplitude of 0, and outputs a waveform whose amplitude fluctuates as shown in FIG. 3 (E) when the reflecting object is a moving object such as a human.
The data is supplied to the microcomputer 12e via the line d.

The microcomputer 12e receives a received signal (FIG. 3C) supplied from the A / D converter 12d.
It is determined whether or not there is an occupant in the passenger seat 1 and whether or not the child seat 5 is installed based on the (digitalized signal of (E)). I do.

Next, an outline of the judgment operation of the microcomputer 12e will be described with reference to FIG. That is, in step 100, the distance from the dashboard 10;
In other words, the transmitting and receiving ultrasonic elements 11a (11
b), the distance in the direction of the backrest of the seat 1 is calculated based on the time required from the emission of the ultrasonic wave to the reception thereof. When it is determined in step 200 that the calculated distance is smaller than the reference value, the child seat 5 When it is determined that the airbag is installed as indicated by 7, the process proceeds to step 500, where the deployment of the airbag is disabled, and the process returns to step 100.

When it is determined in step 200 that the distance calculated in step 100 is larger than the reference value, in step 300, the fluctuation width v ₁ of the amplitude of the detection output and the time t ₁ are set to the respective predetermined values v _X. , T _X
If the variation width v ₁ is larger than the predetermined value v _X and the time t ₁ is smaller than the predetermined value t _X, it is recognized that the occupant 3 is present in the front passenger seat 1, and then step 400
If it is determined that the occupant 3 does not exist,
00, and if it is determined in step 400 that the occupant 3 is present, the flow proceeds to step 600, where the distance from the transmitting and receiving ultrasonic elements 11a (11b) to the occupant 3 is received from the emission of ultrasonic waves. The next step 700 is to instruct the airbag to be deployable at a timing based on the distance calculated in step 600, and then the process returns to step 100.

With this configuration, for example, when there is nothing in the passenger seat 1, the ultrasonic wave is only reflected by the backrest, so that the maximum distance is detected.
The deployment of the passenger airbag is prevented and the passenger seat 1
When the occupant 3 is seated in the vehicle, the airbag for the passenger seat can be deployed. Furthermore, child seat 5
Is installed, since the ultrasonic wave is reflected on the back of the child seat 5, the minimum distance is detected,
The deployment of the passenger airbag is prevented.

[0017]

As described above, according to the first aspect of the present invention, the detection of the occupant in the passenger seat and the detection of the child seat can be performed by one unit, and the effect that the cost can be reduced is exhibited. Further, according to the second aspect, an effect that the occupant detection of the passenger seat can be easily performed is exhibited.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram for explaining an overall outline of a first embodiment according to the present invention.

FIG. 2 is an explanatory diagram of the entire circuit according to the present invention.

FIG. 3 is an explanatory diagram of waveforms of the circuit shown in FIG. 2;

FIG. 4 is a flowchart explanatory diagram of the microcomputer in FIG. 2;

FIG. 5 is a state explanatory view when a child seat is attached to the passenger seat 1.

FIG. 6 is an explanatory diagram for explaining a conventional occupant detection method.

FIG. 7 is an explanatory diagram for detecting a conventional child seat.

[Explanation of symbols]

 Reference Signs List 1 seat 3 occupant 5 child seat 6 control circuit 12e mylocomputer 11a transmitting ultrasonic element 11b receiving ultrasonic element 12d A / D converter

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Toshikazu Sawahata 2-1910 Nisshincho, Omiya-shi, Saitama Kansai Co., Ltd.

Claims (2)

[Claims] 1. A first device installed in front of a passenger seat for continuously outputting ultrasonic waves toward the passenger seat for a first predetermined time.
And a second state that is continuously output for a second predetermined time shorter than the first predetermined time, and is output. When the state changes from the second state to the first state, there is no output. An ultrasonic transmitter that is in a state, an ultrasonic receiver that receives an ultrasonic wave output from the ultrasonic transmitter and reflected by an object on the passenger seat, and an ultrasonic wave that is intermittent from the ultrasonic transmitter. A distance calculation unit that calculates a distance from the ultrasonic transmitter to an object on a passenger seat based on an output of the ultrasonic wave that is output to the ultrasonic receiver based on a reception timing at the ultrasonic receiver; An object detection unit that detects the presence or absence of an object on the passenger seat by comparing the fluctuation of the envelope of the ultrasonic wave output from the receiver with a reference value, and the reference value is the distance calculated by the distance calculation unit. Compared to,
An airbag deployment control circuit that outputs an airbag deployment non-permission signal when the reference value is smaller than the reference value, and that outputs the airbag deployment permission signal in response to a detection signal from the object detection unit. Characterized passenger occupant protection device. 2. The object detection unit calculates a voltage difference and a time between characteristic points of a waveform of an envelope of a received ultrasonic wave, and when the voltage difference and the time exceed a reference value, an occupant enters the passenger seat. The passenger seat occupant protection device according to claim 1, wherein it is determined that there is a passenger.