JP3457515B2 - Occupant protection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] The present invention relates to a vehicle mounted on a vehicle.
Occupant protection systems, especially for vehicles
To protect the occupant from side-to-side collisions
The present invention relates to an occupant protection device having a protection function. [0002] 2. Description of the Related Art An occupant protection device is provided for occupant protection in the event of a collision.
And the occupant hits the vehicle interior equipment.
This is a device to reduce injury due to
There are a bag and a seat belt pretensioner. Airba
The bag inflates the bag between the occupant and indoor equipment during a collision.
To reduce contact injury with passengers' indoor equipment
The seat belt pretensioner is
Immediately tighten the seat belts to connect the occupants to the indoor equipment.
It is intended to alleviate tactile disorders. [0003] Japanese Patent Application Laid-Open No. 8-119060 describes an airbag.
As described in the official gazette, a collision from the front of the vehicle
Front collision airbag and vehicle side to be activated in response to so-called front collision
Side collision air activated in response to a collision from one side, so-called side collision
There is a bag, and these activation controls are controlled by one electronic control unit.
Often done in knitwear. [0004] By the way, this kind of power
The personnel protection device detects acceleration changes due to collisions.
Sensors are provided, each of which should be detected.
It is located at an optimum location according to the acceleration direction. Ma
Usually, a collision determination means is provided for each sensor,
Together with the sensor, and collide on the sensor unit side
The passengers against the central electronic control unit
Sends a signal (start request signal) requesting activation of the protection means
It is supposed to. [0005] The start request signal is a binary signal,
The communication between the unit and the electronic control unit is a binary signal.
Values correspond to the high and low voltage values.
It is possible to do. For example, an electronic control unit on the receiving side
Power supply and a resistor with one end connected to it.
Then, a switch whose one end is grounded to the sensor unit on the transmitting side
Switch (transistor), and the other end of this switch
Connect the other end of the resistor on the electronic control unit side via a communication path.
A configuration of column connection is conceivable. According to this configuration, the switch on the sensor unit side is provided.
When the switch is on, the resistance of the electronic control unit is
The other end, that is, the potential of the input terminal of the electronic control unit
The value is obtained by subtracting the voltage drop at the resistor from the voltage.
When the switch is off, the potential of its input terminal is
To be raised. In other words, start on the sensor unit side
If the switch is turned on and off based on the request signal,
The voltage appearing at the input terminal of the slave control unit is
Either high or low depending on the state.
As a result, the electronic control unit receives the start request signal.
It will be. However, such a sensor unit side
The power of the input terminal on the electronic control unit side is controlled by switch control.
According to the configuration in which the pressure is directly changed, the sensor unit and
The voltage of the communication path with the slave control unit fluctuates greatly,
There is a problem that noise radiation due to this communication path is large.
In particular, since the occupant protection device is very urgent, the start request signal
Communication between the vehicles is performed at a relatively high speed. for example
For example, a pulse signal with a frequency of about 50 KHz is a start request signal.
When used as
Or the frequency band of the FM radio signal,
It interferes with FM radio reception. [0009] In addition, in this configuration, the switch is turned on and off.
Communication is performed by control.
, The impedance of the communication path becomes high. Communication channel
If the impedance of the
Low sound quality. [0010] SUMMARY OF THE INVENTION The occupant protection system of the present invention is described.
The activation device was made to solve such a problem
The occupant is restrained in the event of a vehicle collision.
In the occupant protection device that protects the occupants, the occupants are restrained.
One or more occupant protection means operating in
An electronic control unit for controlling the activation of the worker protection means;
A communication path is formed between the electronic control unit and the vehicle.
Activating the occupant protection means based on the acceleration-related value in the left-right direction of the vehicle
The electronic control unit sends a start request signal requesting the operation via a communication path.
The unit has an acceleration detection unit that transmits to the
The request signal is a binary signal,The electronic control unit has a negative feedback
With an operational amplifier, and the inverting input of this operational amplifier
A start request signal for the acceleration detection unit is sent to the terminal via a communication path.
Signal output terminal,Two of these binary signals
Values correspond to the forward and reverse directions of the current on the communication path.
Communication between the electronic control unit and the acceleration detection unit.
Is what you do. Signals are transmitted according to the direction of current flow.
The signal is transmitted depending on the voltage level.
In comparison, the voltage fluctuation of the communication path is small. Therefore, the voltage
Noise radiation due to fluctuations is also reduced. Also, the signal transmission by the direction of the current is
Eliminates the situation where the impedance of the communication path is high
Therefore, the noise resistance is also good. [0013] FIG. 1 shows an embodiment of the present invention.
It is a figure showing arrangement of each component of an occupant protection device. Real truth
The occupant protection device according to the embodiment includes an airbag as occupant protection means.
1 to 4 and seat belt pretensioners 5, 6,
Electronic control unit 11, acceleration detection units 7, 8
And front satellite acceleration sensors 9 and 10
Each of them has a predetermined
Placed in place. [0014] Of the airbags, a front collision airbag 1 and
And 2 are located in front of the driver and passenger seats,
The side collision airbags 3 and 4 are provided in the driver's seat and the passenger's seat.
It is arranged in the seat or at the B pillar. these
Some airbags have an ignition device called a squib.
In the event of a collision, the electronic control unit 11
The filament generates heat and burns the gas generating agent.
Opens the airbag. Also, the seat belt pretensioner 5 and
And 6 are located in the seatbelt mountings on the driver's seat and the passenger's seat.
And each is provided with a squib.
In the event of a collision, the electronic control unit is
The cut 11 generates heat in the filament inside the squib to
Burns the steam generator, but in the case of a pretensioner,
Of the seat belt using the gas pressure
I do. The acceleration detecting units 7 and 8 are respectively
This is a unit that detects acceleration changes due to side collision on the side where
Knit, and the acceleration-related value, here, the lateral acceleration
When the integrated value during a fixed period exceeds a predetermined threshold
And the corresponding airbag or seatbelt pretension
The electronic control unit sends a start request signal to start the
To the client 11. The electronic control unit 11 includes an acceleration detecting unit.
When an activation request signal is received from the unit 7 or 8,
Airbag or seatbelt pretensioner screen.
Eve is operated by passing an ignition current. In addition, the
An acceleration sensor that detects speed changes is provided.
Integral value of longitudinal acceleration, which is a speed-related value, during a predetermined period
The corresponding airbag when
Or activate the squib of the seat belt pretensioner.
Let Front satellite acceleration sensors 9 and 10
Is a sensor that detects an offset collision from the front, for example.
For example, in the front left half of the vehicle body 12,
If there is a collision, the acceleration detected by the acceleration sensor 10
Speed is greater than acceleration detected by acceleration sensor 9
No. In this case, the acceleration sensor 10 is turned on,
The degree sensor 9 remains off. At this time, the electronic control unit
The knit 11 determines that an offset collision has occurred,
Front collision airbags 1, 2 or seat belt pretension
Threshold of acceleration related value for frontal collision which is the operation standard of
Lower the value. As a result, the offset collision
In the case, the acceleration sensor in the electronic control unit 21
Even front-end airbags 1, 2 or sea
The belt pretensioners 5 and 6 operate. Body 12
Similarly, in the case of an offset collision in the right half, the offset
If a collision is determined, the threshold value of the acceleration related value for
Can be lowered. Next, referring to FIG. 2, the inside of each component will be described.
The configuration and a specific connection relationship will be described. Note that in FIG.
Are acceleration detection units
Seat, airbag, seat belt pretensioner, flow
The same configuration is used for the left and right acceleration sensors.
For simplicity, the right side of the vehicle body 12, ie, the driver's seat
Side acceleration detection unit 7, airbags 1, 3, seat
Belt pretensioner 5 and front acceleration sensor
9 is drawn as a representative. Also, correspondingly, each squared
Current in electronic control unit 11 for personnel protection means
The supply circuit is also drawn only for the driver's seat side,
The ignition current supply circuit is omitted. The electronic control unit 11 is a DC-DC booster.
Control circuit 22, satellite power supply control circuit 23, 5V power supply
Regulator 24, squib ignition control circuit 25, squib
Diagnostic circuit 26 and communication interface circuit 2
7 is provided. The DC-DC boost control circuit 22 is not shown.
12V voltage of the onboard battery needed for squib ignition
This is a circuit that boosts the voltage to about 15 V, for example. Satella
The power supply control circuit 23 operates the acceleration detection unit 7.
Power supply transformer to regulate the supply of power needed to
This is a circuit for controlling the resistor 28. 5V power supply regulation
The circuit 24 includes various circuits inside the integrated integrated circuit 21 and its peripherals.
This is a circuit that supplies a power supply voltage of 5 V to the side circuit. The squib ignition control circuit 25 includes an airbag
1, 3 and the seat belt pretensioner 5
Of the ignition current supplied to each of the squibs 1a, 3a, 5a
One of the ignition transistors 32 to perform on / off switching
34 is a circuit for controlling the circuit. This squib ignition control circuit
25: ON / OFF control of the ignition transistors 32 to 34
Is a start request signal from the microcomputer 30 and a communication interface.
Acceleration detection unit provided through the interface circuit 27.
This is performed based on a start request signal from the unit 7. The other ignition transistors 36 to 38
Is directly controlled on / off by the microcomputer 30.
It is. The squib diagnostic circuit 26 is provided for each squib.
For 1a, 3a, 5a, a weak current that does not lead to ignition
Measure the resistance while flowing, and check if each squib is normal.
This is a circuit for self-diagnosis. The communication interface circuit 27 is an electronic
The control unit 11 decodes the acceleration detection units 7 and 8
This is an interface circuit for performing digital communication. The front collision acceleration sensor 29 is an electronic acceleration
Sensor, an electrical signal corresponding to the detected acceleration,
That is, the acceleration signal is always output. Here, the front
The speed sensor 29 has a linear output characteristic
The diaphragm type acceleration sensor that can obtain
ing. The microcomputer 30 performs acceleration for frontal collision.
The acceleration signal output from the degree sensor 29 is input and the acceleration
The integral value in the predetermined period is continuously calculated. this
The integrated value is called the acceleration-related value here, and
The computer 30 converts the acceleration-related value into a predetermined frontal collision.
Start request signal when the threshold is exceeded.
Is output to the squib ignition control circuit 25,
The ignition transistors 36 to 38 are turned on. Note that this
The value of the threshold for frontal collision is determined by the front satellite acceleration sensor.
If either of the output signals of the
Will be lower. An ignition current is supplied to the squibs 1a, 3a and 5a.
The supplied ignition current circuit is a DC-DC boost control which is a power supply.
Circuit 22, power supply control Tr28, safing sen for frontal collision
, Rectifier diodes 42 and 43, upstream side
Ignition transistor group 35, downstream ignition transistor group 3
9. Side collision safing sen in acceleration detection unit 7
And 53. [0029] Safting sensor 31 for front collision and side collision
Acceleration sensor exceeds a predetermined value.
A mechanical collision detector that switches on when added
And safety against malfunction of the acceleration sensors 29 and 51.
Functions as a switch. The backup capacitor 44 is used when an abnormality occurs.
Backup power to supply ignition current to each squib
Source. For example, in the event of a collision, an electronic control
The wire harness supplying power to the knit is disconnected, etc.
The ignition current cannot be supplied as in the case of
Sometimes, the ignition voltage is replaced with the DC-DC boost control circuit 22.
Feed the stream to the squib. The acceleration detection unit 7 has a 5V power supply regulation.
Product of the accelerator 50, the side collision acceleration sensor 51, and the acceleration.
My unit that performs minute calculation and communication with the electronic control unit 11
Cross computer 52 and the above-mentioned side collision safing
And a sensor 53. 5V power regulator 50
Is the power control transistor 2 in the electronic control unit 11
8 to receive the side collision acceleration sensor 51 and
And a 5V voltage power supply for the microcomputer 52
Function. The side collision acceleration sensor 51 is a front collision acceleration.
An electronic acceleration sensor similar to the sensor 29,
An Afram-type acceleration sensor is employed. The microcomputer 52 calculates a side collision acceleration.
The acceleration signal from the sensor 51 is input, and the acceleration
Continuously calculate the integrated value (acceleration-related value) for a predetermined period
Put out. This acceleration-related value is constantly monitored.
And a second, higher threshold,
The electronic control unit is compared when it is equal to or greater than the second threshold.
Airbag or seat for side collision corresponding to knit 11
Start request signal for starting the belt pretensioner
Send Further, the microcomputer 52 is operated by an acceleration
Self-diagnosis in the degree detection unit 7, for example, side collision acceleration
Diagnosis such as whether the degree sensor 51 is normal
Periodically and the result is dialed to the electronic control unit 11.
It is sent out at a fixed period as a switching signal. However, this
The acceleration signal exceeds the first threshold
Is forbidden while in use. FIG. 3 is a diagram showing a micro unit of the acceleration detecting unit 7.
Communication interface between the computer 52 and the electronic control unit 11
FIG. 10 is a circuit diagram showing a communication circuit with the interface 27.
The communication interface 27 is an operation to which negative feedback is applied.
A current-voltage conversion circuit 97 including an amplifier 90 is provided.
The current-voltage conversion circuit 97 includes an operational amplifier 90, a resistor 9
1, 93, 95, capacitor 92 and reference voltage power supply 9
4 whose output terminal is the input of the inverter 96.
Connected to terminal. The reference voltage power supply 94 is
It is set to 2.5 V, and its positive electrode is
Is connected to the non-inverting input terminal. Negative feedback
Operational amplifier 90 is a so-called imaginary short
So that the voltage at the inverting input terminal is always 2.5 V
Operate. The input side of the current / voltage conversion circuit 97,
The resistor 9 connected to the inverting input terminal of the operational amplifier 90
3 and the communication path 99, resistors 85 and 86
And a protection circuit 88 comprising a capacitor 87.
You. The protection circuit 88 is connected to the communication path 9 due to static electricity or the like.
9 is not destroyed by the surge noise applied to
It is a circuit for making sure. The micro computer on the acceleration detection unit 7 side
The computer 52 is connected to the central processing unit 80 and its output terminal.
Protection circuit 84 provided. The protection circuit 84
Like circuit 88, it protects the circuit from surge noise.
And includes resistors 81 and 82 and a capacitor 83.
ing. The central processing unit 80 operates from 0V and 5V.
Outputs a start request signal consisting of a combination of binary voltage values
I do. The output voltage of the central processing unit 80 is 0 V,
Output signal of the operational amplifier 90
To lower the potential of the inverting input terminal,
The amplifier 90 should maintain the voltage of the inverting input terminal at 2.5 V.
Raise the output voltage of the spider. At this time, the communication path 99
From the electronic control unit 11 side to the acceleration detection unit 7 side
Electric current flows. When the output voltage of the central processing unit 80 is 5 V,
When the signal is at a high level, this output signal
In order to raise the potential of the inverting input terminal of 0,
To maintain the voltage of the inverting input terminal at 2.5V.
The output voltage is decreased. In this case, the communication path 99
The acceleration detection unit 7 sends a signal to the electronic control unit 11.
The current flows. As described above, the output voltage of the central processing unit 80 is
When the output voltage of the current-voltage conversion circuit 97 is high,
The pressure decreases, and conversely increases when the level is low. Electric
The output of the current-voltage conversion circuit 97 is input to an inverter 96.
As a result, the communication interface
The high level and low level of the output of
And the high level and low level of the output of the central processing unit 80.
Is supported. FIG. 4 is a voltage waveform of each part of the communication circuit of FIG.
FIG. 5 is a signal waveform diagram showing The vertical axis is divided into upper and lower
Each of them shows a voltage value, and the horizontal axis shows time. wave
Type A is an output signal of the central processing unit 80, and waveform B is a communication path 99.
And the waveform C is the voltage at the node between the resistors 85 and 86.
Values and waveform D are output voltage values and waveforms of the current-voltage conversion circuit 97.
E is an output voltage value of the inverter 96. Referring to FIG. 7, the operation in the period T is explained.
When it is described, the output voltage (waveform A) of the central processing unit 80 becomes high.
Changes from low to low, the voltage (waveform B) of the communication path 99 also changes.
It starts to fall accordingly, but the current-voltage conversion circuit 97
Since the output voltage (waveform D) increases, the voltage of the communication
Does not increase so much. Here, the communication path 9
9 changes between 2V-4V. Inverter
96 inverts and amplifies this change and outputs (waveform E).
Note that the voltage of the communication path 99 varies between 2V-4V.
Is that the protection circuits 84 and 88 for surges are provided.
If this protection circuit is not provided, the communication path 99
The voltage hardly changes like the waveform C. As described above, the activation request signal is
Since the current is transmitted in the opposite direction,
The voltage fluctuation on the path 99 is very small. Therefore, communication
To minimize noise radiation due to voltage fluctuations in the path 99
Can be. Also, a current always flows through the communication path 99.
In other words, since there is no high impedance, noise
Less susceptible to Next, the present embodiment configured as described above
The overall operation of the occupant protection device will be described. First, a collision from the front will be described.
You. When the vehicle body 12 receives a collision from the front, the electronic control unit
The acceleration sensor 29 for front collision in the knit 11
Detect changes in speed. The microcomputer 30
Acceleration-related value by constantly integrating the ever-changing acceleration value
Output at the time of a frontal collision.
Rises sharply. And this acceleration related value is
If it exceeds the preset front collision set value, it is judged as a front collision
A start request signal is output, and the squib ignition control circuit 25
The ignition transistors 32 and 33 are turned on. At this point
Micro transistors are used for the fire transistors 36 and 37.
Data 30 is directly turned on. At this time, the safing sensor 31 for front collision
Is also turned on by collision, DC-DC boost system
From the control circuit 22 to the frontal safing sensor 31,
Transistor 32, squib 1a, ignition transistor 36
And a circuit grounded through the DC-DC boost control circuit 22
From the frontal safing sensor 31, the diode 42,
Ignition transistor 33, squib 5a, ignition transistor
And a closed circuit that is grounded through the driver 37,
Airbag 1 and seat belt pretensioner 5
to start. Similarly, the passenger seat omitted from FIG.
Side airbag 2 and seat belt pretensioner 6
Also starts. In the case of an offset collision, which is one of the front collisions,
Are front satellite acceleration sensors 9 and 10
Only one of them is turned on, and the squib ignition control circuit 2
In step 5, the front collision set value is lowered based on this. before this
Except for the change of the collision setting value, it operates in the same way as a normal front collision,
When the acceleration related value exceeds the set value for front collision after this change,
Airbags 1, 2 and seat belt pretensioner
5 and 6 are activated. Next, the operation at the time of a side collision will be described. Body 1
2 receives a collision from the right side of the acceleration detection unit 7
Change in acceleration due to this side collision
Is detected, and the microcomputer 52 calculates the acceleration-related value.
Is calculated. If this acceleration related value is greater than or equal to the second threshold
Then, the microcomputer 52 sends an activation request signal.
I believe. The electronic control unit 11 sends this activation request signal
The squib ignition control circuit 25 receives the ignition transistor 3
The microcomputer 30 controls the ignition transistors 3 and 34.
The stars 37 and 38 are turned on. This side
The collision safety sensor 53 is closed due to this side collision.
If the DC-DC boost control circuit 22
Sensor 53, ignition transistor 34, squib 3
a, a circuit grounded via the ignition transistor 38,
From the C-DC boost control circuit 22
, A diode 43, an ignition transistor 33,
Eve 5a, circuit grounded via ignition transistor 37
Are formed, and the side collision airbag 3 and the seat on the driver's seat side are formed.
The belt pretensioner 5 is activated. When a collision is received from the left side of the vehicle body 12
The acceleration detection unit 8 detects this collision and requires activation.
Request signal to the electronic control unit 11,
The seat 11 is on the passenger seat side based on the activation request signal.
Impact airbag 4 and seat belt pretensioner 6
Start Next, the starting of the acceleration detecting unit 7 will be described.
The operation of transmitting the operation request signal and the diagnosis signal will be described.
You. FIGS. 5 and 6 show the acceleration detection unit 7.
Showing the operation of the microcomputer 52 of FIG.
FIG. 5 is a chart related to the interruption processing of the side collision determination.
FIG. 6 relates to a diagnostic interrupt transmission process.
It is. FIG.
The timing chart of the side collision judgment and transmission processing
FIG. 7A shows an acceleration-related value which is an integral value of the acceleration.
FIG. 5B shows the time change of the diagnostic signal.
Signal and the start request signal transmission timing.
You. First, the side collision determination interrupt processing will be described.
Will be explained. As shown in FIG.
Reference numeral 52 denotes an acceleration based on the acceleration signal from the side collision acceleration sensor 50.
The speed value G is sampled (step 101), and
Of the acceleration value G sampled within a predetermined period at
The current acceleration value is added to the value and a predetermined value is calculated from the integrated value.
Delete the oldest sampled acceleration value in the period
(Step 102). Here, this operation is called the integral operation
Call. Next, this integral value, which is an acceleration-related value, is
2 is compared with the threshold value Th2 (step 103).
If the threshold value is equal to or greater than Th2, an activation request signal is transmitted.
(Step 104). In step 103, the integrated value is
If it is smaller than the threshold value Th2, the process proceeds to step 105,
Set the integral value to a value smaller than the second threshold value Th2
Is compared with the first threshold value Th1. Where the product
If the minute value is equal to or greater than the first threshold value Th1, the diagnostic signal
Transmission of signals other than the start request signal such as
106). In step 105, the integral value becomes the first threshold value.
If smaller than, allow transmission of diagnostic signals, etc.
(Step 107). This interrupt processing is performed by a diagnosis signal described later.
In the diagnostic signal transmission enabled state during signal interrupt processing
A cycle shorter than the cycle (about 5 ms), for example, 0.2
It is repeated at a cycle of about 5 ms. Next, the diagnostic signal transmission interrupt shown in FIG.
The processing will be described. First, the side collision determination interrupt of FIG.
Transmission of diagnostic signal etc. is prohibited in processing
It is determined whether or not this is the case (step 201). Transmission prohibited state
, The subsequent steps 202 and 203 are skipped.
Return to step 201 again and repeat this
And waits until the transmission prohibition is released. Step
That the transmission of diagnostic signals etc. is not prohibited by
If it is determined, a diagnostic signal is transmitted after 50 ms.
(Steps 202 and 203). Next, under these two processes,
FIG. 7 shows the timing of the transmission signal when a collision occurs.
Will be explained. Assuming that a side collision occurs at time t1, FIG.
As shown in (a), there was almost no change until then.
The acceleration-related value (integral value) starts to rise sharply. At time t2
When the acceleration-related value exceeds the first threshold value Th1, at time t3
If the second threshold value Th2 is exceeded, the time t2
Diag signals 501 and 502 are transmitted every 50 ms
However, at time t2, a collision is determined by the side collision determination interrupt processing.
Transmission of iag signal etc. is prohibited, so if there is no side collision
The diagnostic signal 503 to be transmitted is not transmitted. Therefore, the activation request signal is transmitted at time t3.
Transmission of this activation request signal
It is not disturbed by the Ag signal 503. In this embodiment
Is a two-byte 1-byte (8-bit) code.
One of the code signals 60
When the 1 and the other code signal 602 are transmitted,
This means that the motion request signal has been transmitted. Table 1 shows an example of the type of transmission data and the like.
It is. [0059] [Table 1] As shown here, the activation request signal includes 16
Uses two types of code signals, "98" and "0E" in hexadecimal notation
The two types of code signals are transmitted at intervals of 96 μs.
To send alternately. Normal as a diagnostic signal
Is a hexadecimal "E0", indicating an error.
Signal is “1C”. Therefore, FIG.
The signals 501 and 502 shown in FIG.
"E0" has been sent. FIG. 8 shows communication in the acceleration detection unit 7.
FIG. 1 is a diagram illustrating a configuration of a system. Microcomputer
Reference numeral 52 denotes an electronic control unit for transmitting a start request signal, a diagnostic signal, and the like.
8 bits to be transmitted when transmitting to
The data is written to the data register 61. Data Regis
The data written to the data register 61 is transferred to the shift register 62.
The communication interface of the electronic control unit 11 is transmitted serially.
Interface 27. Therefore, the diagnosis
Is transferred from the data register 61 to the shift register 62
Immediately after that, the activation request signal is sent to the data register 61.
Even if written, the dial in shift register 62
Transmission of the activation request signal unless the transmission of the
Can't do it. However, according to this embodiment, the activation request
Before sending a signal, send a signal other than the activation request signal,
For example, since the transmission of the diagnostic signal is prohibited, the activation request signal
When trying to send a diagnostic signal etc.
And the activation request signal is sent to the data register 61.
As soon as it is written, it is transferred to the shift register 62 and
It is transmitted to the child control unit 11. The electronic control unit 11 on the communication path 99
The communication with the acceleration detection unit 7 has already been described with reference to FIG.
As described, the two values of the binary signal are
The communication path 99
Voltage fluctuation is small. Therefore, noise radiation is almost
No. Also, since current always flows through the communication path 99,
Impedance is always low and is affected by external noise.
Hateful. In this figure, the protection circuit shown in FIG.
The illustration of 84 is omitted. FIG. 9 is a diagram showing the structure of transmission data.
Send one start bit before data bit
Followed by 8-bit data bits including parity bits
And one stop bit at the end.
You. By the way, the start bit and the stop bit
In the present embodiment, each type of data signal including
One or both of the adjacent bits
Are selected at the same level. Transmission data
Is configured in this way, the effective transmission frequency is
1 or less, and the frequency can be
Noise can be prevented from being caused by high
You. Table 2 lists such bit arrangements.
When the start bit is low level “0”,
Bit is high level “1”, communication idle period is high
It is assumed that the level is “1”. [0068] [Table 2] In Table 2, bit 0 of the transmission data is the most significant.
The lower bit 7 is the most significant 8-bit data.
Bits 0 to 3 correspond to the lower number in hexadecimal notation,
Bit 4 to bit 7 correspond to the upper hexadecimal number
You. Bit 7 is used as a parity bit.
You. As can be seen from this table, the activation of the present embodiment
The aforementioned hexadecimal “9” used in the request signal
8 "," 0E "and" E "used for the diagnostic signal.
Both “0” and “1C” are “each bit is adjacent before and after.
One or both bits are at the same level. ''
And the generation of noise is suppressed. [0071] As described above, the occupant protection of the present invention is described.
According to the device, the electronic control unit and the acceleration detection unit
The signal is transmitted between the forward and reverse directions of the current
The signal is transmitted according to the voltage level.
In comparison, the voltage fluctuation of the communication path is small. Therefore, voltage change
Noise radiation accompanying movement is also reduced. Therefore, the same vehicle
Other communication systems on board, such as radio
No noise is given to the receiver. The signal transmission based on the direction of the current is
Eliminates the situation where the impedance of the communication path is high
Therefore, the noise resistance is also good.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view showing an arrangement of each component of an occupant protection device according to an embodiment of the present invention. FIG. 2 shows an electronic control unit 11 and an acceleration detection unit 7
The block diagram which clarified the internal structure of FIG. FIG. 3 is a circuit diagram showing a communication circuit according to the embodiment. 4 is a diagram showing voltage waveforms at various points in the communication circuit shown in FIG. 3; FIG. 5 is a flowchart showing a side collision determination interrupt process executed by a microcomputer 52 in the acceleration detection unit 7; FIG. 6 is a flowchart showing a diagnostic signal interruption process. FIG. 7 is a timing chart of side collision determination and signal transmission. FIG. 8 is a block diagram showing a transmission system of the microcomputer 52. FIG. 9 is a diagram showing transmission data and a structure. [Description of Signs] 1, 2 ... front collision airbag, 3, 4 ... side collision airbag, 5, 6 ... seat belt pretensioner, 7, 8 ... side collision acceleration detection unit, 9, 10 ... Front satellite acceleration sensor, 11: electronic control unit, 25: squib ignition control circuit, 29: front collision acceleration sensor, 3
0, 52: microcomputer, 51: side collision acceleration sensor, 35, 39: ignition transistor group, 1a, 3
a, 5a: squib, 80: central processing unit, 84, 88 ...
Protection circuit, 90: operational amplifier, 97: current-voltage conversion circuit, 99: communication path.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-8-282432 (JP, A) JP-A-6-69965 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60R 21/16-21/32 B60R 22/48

Claims (1)

(1) An occupant protection device for protecting an occupant by restraining the occupant in the event of a vehicle collision, comprising: one or more occupant protection means operable to restrain the occupant; An electronic control unit for controlling the activation of the occupant protection means, and a communication path is formed between the electronic control unit and the electronic control unit. start request signal and an acceleration detection unit to be transmitted to the electronic control unit via said communication path, said activation request signal is a binary signal, said electronic control uni
The unit has an operational amplifier with negative feedback,
To the inverting input terminal of the amplifier via the communication path.
Output start request signal output terminal
The communication between the electronic control unit and the acceleration detection unit is performed by associating the two values of the binary signal with forward and reverse current directions on the communication path, respectively. Protection device.