JPH04362445A - Warning device - Google Patents

Abstract

PURPOSE:To provide a warning device having only one indicator which can give an alarm for the defective mounting of a seat belt and the failure of an occupant protection device, and also can inform an occupant of a broken electric circuit when the occupant protection device is not connected to the indicator. CONSTITUTION:The switching actions of switching transistors 8 and 11 are made different in response to the warning signal and the signal-indicating the connecting condition of a failure warning indicating device 3 which are outputted from a seat belt warning circuit 7 and a failure detection circuit 9 respectively, so that the indication pattern of an indicator 10 is thereby changed.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention provides an alarm to remind occupants of vehicles such as automobiles to fasten their seat belts, and to warn whether or not a failure has occurred in occupant protection devices such as pretensioners and airbags. Regarding equipment.

0002

2. Description of the Related Art Conventionally, a seatbelt alarm indicator that warns that the seatbelt is fastened and an occupant protection device alarm device that alerts the occupant of the occurrence of a failure of the occupant protection device are usually provided separately and independently. Ta.

0003

[Problems to be Solved by the Invention] However, if separate displays are provided for the seat belt warning display and the warning device for the occupant protection system, the cost of the display increases as a proportion of the product price, and This requires a large space to install the display, and there is also the disadvantage that the vehicle driver looking at the display is likely to confuse the display and misrecognize it.

[0004] In order to eliminate such drawbacks, attempts have been made to display the warning of the occupant protection device using a seatbelt warning indicator, but the connection between the occupant protection device and the seatbelt warning indicator is difficult. If the seatbelt warning indicator is incomplete or not connected at all, the seatbelt warning indicator will not display any warning even if the occupant protection device is malfunctioning, and the driver of the vehicle will not be able to detect any malfunction in the occupant protection device. There was a risk of mistakenly believing that there was no such thing.

[0005] The present invention has been made in order to eliminate the above-mentioned drawbacks of conventional warning devices, and uses only one display to warn of the fastening of a seat belt and to warn of a failure of an occupant protection device. It is an object of the present invention to provide a warning device which can also display this information when an occupant protection device is not connected to a seatbelt warning display.

[0006]

[Means for Solving the Problems] The warning device of the present invention includes a seatbelt warning means for outputting a warning signal warning that the seatbelt is fastened, and detects a failure of an occupant protection device and responds to the presence or absence of the failure. In the alarm device, the failure alarm means is connected to the display means, and the alarm device includes a failure alarm means that outputs an alarm signal that is output from the seatbelt alarm means, and a display means that displays an alarm based on at least the alarm signal output from the seatbelt alarm means. The present invention is characterized in that a display control means is provided for changing the display mode of the display means depending on whether or not the failure alarm means is present and an alarm signal output from the failure alarm means.

[0007]

[Operation] In the alarm device of the present invention, the display mode of the display means is changed depending on whether or not the failure alarm means is connected to the display means and the alarm signal output from the failure alarm means. The display means can alert the driver to fasten the seat belt and display whether or not there is a failure in the occupant protection device, and it is also possible to easily determine whether or not the failure alarm means is connected to the display means, so that the failure of the occupant protection device can be easily determined. There is no risk of misjudging the presence or absence of

[0008]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings.

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

This embodiment includes a power source E, an ignition switch 1 that is connected in series with the power source E and supplies power from the power source E to various parts, and a power source E that supplies power through the ignition switch 1. The seatbelt alarm display device 2 includes a seatbelt alarm display device 2, a failure alarm display device 3, and a display device 4 made of a light emitting diode or the like.

The seat belt warning display device 2 and the failure warning display device 3 are electrically connected through terminals 5,5 and 6,6.

In the seat belt alarm display device 2, the seat belt alarm circuit 7 is supplied with power from the power source E via the ignition switch 1, and when the ignition switch 1 is turned on, it issues a warning to fasten the seat belt for a predetermined period of time. Outputs a pulse signal. The output terminal of the seat belt warning circuit 7 is connected to the base of a switching transistor 8, the collector of the switching transistor 8 is connected to the display 4 and the terminal 5, and the emitter is connected to the terminal 6 and grounded.

The failure alarm display device 3 includes a failure detection circuit 9 that outputs a high-level pulse signal when a failure occurs in the occupant protection device, and a switching transistor 10.
11, comparators 12, 13, resistors 14, 15, 16, and a capacitor 17.

The output terminal of the failure detection circuit 9 is connected to the base of a switching transistor 10, the emitter of the switching transistor 10 is grounded, and the collector is connected to the terminal 5. The inverting input terminal of the comparator 12 is connected to the terminal 5, and the collector of the switching transistor 11 is also connected to the terminal 5.

A reference voltage Vs is applied to the non-inverting input terminal of the comparator 12, and a pull-up resistor 14 is applied to the output terminal.
and a capacitor 17 are connected. capacitor 17
The other electrode is grounded via a resistor 16 to form a differential circuit, and is connected to the non-inverting input terminal of the comparator 13.

The reference voltage V is applied to the inverting input terminal of the comparator 13.
TH is applied, and the output terminal is connected to the base of the switching transistor 11.

The base of the switching transistor 11 is pulled up by a resistor 15, and the emitter is connected to the terminal 6 and grounded.

Next, the operation of this embodiment will be explained with reference to the timing chart of FIG.

When the ignition switch 1 is turned on, the power supply voltage shown in FIG. 2(1) is supplied from the power supply E to each circuit.

By applying this power supply voltage, the seat belt alarm circuit 7 outputs a pulse signal shown in FIG. 2(2).

Here, the seat belt alarm display device 2 and the failure alarm display device 3 are not connected to each other, and the terminal 5
and 6 are open (hereinafter referred to as "state 1"), the potential at the connection point between terminal 5 and display 4 (hereinafter referred to as "point (A)") is Since the switching transistor 8 is switched by the pulse signal output from the belt alarm circuit 7, the state is as shown in FIG. 2(3). Therefore, the display 4 performs a blinking display as shown in FIG. 2(4). Here, the pulse waveform in FIG. 2 (4) indicates a high level when the display 4 is lit, and a low level when the display 4 is off (hereinafter, the pulse waveform indicating the operation of the display 4 are all expressed in the same way).

Next, the seat belt alarm display device 2 and the failure alarm display device 3 are connected (that is, the terminals 5, 5
and 6 and 6 are connected to each other), and the occupant protection device is normal without any failure (hereinafter, this state will be referred to as "state 2").

In this case, no output signal is output from the failure detection circuit 9, and the output level of the failure detection circuit 9 is kept at a low level as shown in FIG. 2(5). Therefore, the switching transistor 10 is kept in an off state.

On the other hand, when the ignition switch 1 is turned on, the switching transistor 8 is turned on by the output pulse signal of the seat belt alarm circuit 7 (FIG. 2 (2)), and the potential at point (A) becomes low level. , the output level of the comparator 12 becomes high level, this stepped up signal is differentiated by the capacitor 17, and the connection point between the capacitor 17 and the non-inverting input terminal of the comparator 13 (hereinafter, this point will be referred to as "(B)" Figure 2 shows the potential at
(6).

At the same time as the ignition switch 1 is turned on, the potential at point (B) becomes higher than the reference voltage VTH, and the potential at the output terminal of the comparator 13 (hereinafter referred to as point (C)) is As shown in 2(7), the level becomes high. As a result, the switching transistor 11 is turned on, and current flows from the power source E to the switching transistor 11 and the switching transistor 8 via the display 4, and the display 4 lights up (FIG. 2 (8)).

In this state, after a predetermined period of time has elapsed, the output pulse signal of the seat belt alarm circuit 7 falls and the switching transistor 8 turns off, but since the switching transistor 11 is still on, the display 4 continues to light up. .

During this time, the charge stored in the capacitor 17 continues to be discharged via the resistor 16, and when the potential at point (B) becomes smaller than the reference voltage VTH, the potential at point (C) becomes low level (Fig. 2 (6)). ), (7)), the switching transistor 11 is turned off. At this time, since the switching transistor 8 is off, the potential at point (A) becomes high level as shown in FIG. 2(9). Therefore, the display 4 turns off ((8) in FIG. 2).

Next, when the output pulse signal of the seat belt 7 rises, the display 4 blinks by repeating the same operation as above.

In this way, when the predetermined time period during which the seat belt alarm circuit 7 outputs a pulse signal has elapsed while the display 4 is flashing, the switching transistor 8 is no longer turned on, and therefore (B The potential at point ) is low level, the potential at point (C) is low level, (
The potential at point A) is kept at a high level (Fig. 2 (6), (7)
), (9)), so that the display 4 continues to be turned off (FIG. 2 (8)).

That is, in state 2, the display 4 is in state 1.
The light will blink for a predetermined period of time with a different duty ratio than when the light is on and off (compare (4) and (8) in FIG. 2).

Next, the seat belt alarm display device 2 and the failure alarm display device 3 are connected (that is, the terminals 5, 5
and 6 and 6 are connected to each other), and the occupant protection device has a failure and is abnormal (hereinafter, this state will be referred to as "state 3"). The operation will be described.

In this case, the failure detection circuit 9 outputs a high-level pulse signal indicating an abnormality in the occupant protection device at the same time as the ignition switch 1 is turned on (see FIG.
10)) The switching transistor 10 is turned on by this pulse signal, and the potential at point (A) is kept at a low level (FIG. 2 (11)). Therefore, the indicator 4 lights up at the same time as the ignition switch 1 is turned on, and maintains that state ((12) in FIG. 2).

FIG. 3 is a circuit diagram of a second embodiment of the present invention. In this figure, the same components as in the first embodiment of FIG. 1 are given the same numbers, and their explanations will be omitted.

In this embodiment, the failure alarm display device 3
are a failure detection circuit 9, a switching transistor 11,
A monostable multivibrator (hereinafter abbreviated as "MM") 20, an AND gate circuit (hereinafter abbreviated as "AND") 21, 22, an OR gate circuit (hereinafter abbreviated as "OR") 23, and an inverter 24. have

The trigger input terminal of MM20 is connected to the ignition switch 1, and the output terminal is connected to one input terminal of AND22.

The output terminal of the failure detection circuit 9 is connected to the input terminal of the inverter 24 and one input terminal of the AND 21.

The output terminal of the inverter 24 is connected to the other input terminal of the AND22, and the output terminal of the AND22 is connected to the output terminal of the AND22.
It is connected to one input terminal of R23.

The other input terminal of AND21 is connected to the ignition switch 1, and the output terminal is connected to the other input terminal of OR23.

The output terminal of OR23 is connected to the base of switching transistor 11.

Next, the operation of this embodiment will be explained with reference to the timing chart of FIG.

When the ignition switch 1 is turned on, power from the power source E is supplied to each circuit (FIG. 4(1)), and the seatbelt alarm circuit 7 receives a pulse for a predetermined time, as in the first embodiment. A signal is output (Fig. 4 (2)). As a result, the MM 20 outputs a pulse signal that becomes high level for the set time (in this embodiment, the same time as the seat belt alarm circuit 7 outputs the pulse signal) (Fig. 4 (3)
)).

In state 1, display 4 displays exactly the same as in the first embodiment (FIG. 4(4)).

In state 2, since the output level of the failure detection circuit 9 is low level (FIG. 4 (5)), the output level of the inverter 24 is high level (FIG. 4 (6)).
, the output level of AND22 is high level only while the output pulse signal of MM20 is high level (Fig. 4 (7)
)), this pulse signal is applied to the switching transistor 11 via the OR 23, and the switching transistor 11 is turned on only while the output pulse signal of the MM 20 is at a high level. Therefore, the potential at point (A) is MM20
After the time period during which the output pulse signal is at high level has elapsed, it becomes high level (Fig. 4 (8)), and the display 4 lights up until this time after the ignition switch 1 is turned on (Fig. 4 (8)).
9)).

Next, in state 3, the failure detection circuit 9
, a high-level pulse signal (Fig. 4 (10)) is output at the same time as ignition switch 1 is turned on, and AND2
1, applied to the base of the switching transistor 11 via OR23, so the switching transistor 1
1 is turned on at the same time as the ignition switch 1 is turned on, so the display 4 lights up at the same time and maintains this state (FIG. 4 (11)).

That is, in this embodiment, the display 4
In state 1, it blinks for a predetermined time (Fig. 4 (4)), and in state 2, it remains lit for a predetermined time and then turns off (Fig. 4 (9)).
)), it continues to light up in state 3 ((11) in FIG. 4).

FIG. 5 is a circuit diagram of a third embodiment of the present invention, which realizes the same display mode as the first embodiment of FIG. 1 with a different circuit configuration. In this embodiment, the failure alarm display device 3 outputs a pulse signal having the same frequency and the same duty ratio as the pulse signal output from the seat belt alarm circuit 7, in addition to the circuit of the second embodiment. A pulse generator (hereinafter abbreviated as "PG") 30,
Delay circuit (hereinafter abbreviated as "DLY") 31 and OR
32, AND33.

The PG 30 is supplied with power from the power source E via the ignition switch 1, and starts oscillating at the same time as the ignition switch 1 is turned on.

The input terminal of DLY31 and one input terminal of OR32 are connected to the output terminal of PG30. The output terminal of DLY31 is connected to the other input terminal of OR32, and the output terminal of OR32 is connected to one input terminal of AND33.

The other input terminal of AND33 is connected to the output terminal of MM20, and the output terminal of AND33 is connected to A.
It is connected to one input terminal of ND22. The configuration of other parts is the same as the second embodiment.

Next, the operation of this embodiment will be explained with reference to the timing chart of FIG.

In state 1, the display 4 displays exactly the same display as in the first embodiment (FIG. 6(1)).

In state 2, the output level of the failure detection circuit 9 is kept at a low level, and the switching transistor 11
The switching operation is controlled by the output signal level of AND22.

The PG 30 starts oscillating at the same time as the ignition switch 1 is turned on (FIG. 6 (2)), and the DLY 31 delays the output signal of the PG 30 by a set time and outputs it (FIG. 6 (3)). Since OR32 adds the output signal of PG30 and the output signal of DLY31 and outputs the result, Figure 6
As shown in (4), a pulse signal having a different duty ratio from the output signal of the PG 30 is output from the OR 32. This OR
The output signal of 32 is multiplied by the output signal of MM20 (FIG. 6 (5)) in AND33, and only while the output signal of MM20 is at a high level, the pulse signal of the duty ratio is outputted from AND33. (Figure 6 (6)). In state 2, this pulse signal is AND22, OR2
3 to the switching transistor 11,
This causes the display 4 to blink at a duty ratio different from that in state 1 ((7) in FIG. 6).

In state 3, the switching operation of the switching transistor 11 is controlled by the output pulse signal of the AND 21, so the display 4 displays exactly the same display as in the second embodiment (FIG. 6 (8)). .

That is, in this embodiment, as in the first embodiment, the display 4 blinks for a predetermined period of time in state 1 (FIG. 6(1)), and in state 2, which is different from state 1. It blinks for a predetermined time depending on the duty ratio (FIG. 6 (7)), and remains lit in state 3 (FIG. 6 (8)).

FIG. 7 is a circuit diagram of a fourth embodiment of the present invention, in which the output pulse signal of PG 30 is used as the input signal of AND 21 instead of the voltage of power supply E via ignition switch 1. This embodiment differs from the second embodiment only in this respect, and is completely the same as the second embodiment in other respects. Therefore, only the display mode of state 3 in which the output signal of the AND 21 controls the display mode of the display 4 differs from the second embodiment.

That is, in this embodiment, the display 4
blinks for a predetermined period of time in state 1 (Fig. 8 (1)), and turns off after remaining lit for a predetermined period of time in state 2 (Fig. 8 (2)).
, continues to blink in state 3 (FIG. 8(3)).

FIG. 9 is a circuit diagram of a fifth embodiment of the present invention. This embodiment is a combination of the third embodiment and the fourth embodiment, and is a state 2 in which the output signal of the AND22 controls the switching operation of the switching transistor 11.
This is the same as the third embodiment in that the output pulse signal of the OR32 having a different duty ratio from the output signal of the seatbelt alarm circuit 7 is used as the input signal when the output signal of the AND21 controls the switching operation of the switching transistor 11. PG3 as an input signal when in the governing state 3
This embodiment is the same as the fourth embodiment in that a continuous pulse signal of 0 is used.

That is, in this embodiment, the display 4
blinks for a predetermined time in state 1 (Fig. 10 (1)), in state 2 it blinks for a predetermined time with a different duty ratio than state 1 (Fig. 10 (2)), and in state 3 it blinks for a predetermined time with a different duty ratio than state 1. It continues to blink at the ratio (Figure 10 (3)).

FIG. 11 is a circuit diagram of a sixth embodiment of the present invention.

In this embodiment, the output signal of PG30 and the output signal of MM20 are input to AND40, and this A
The output signal of ND40 and the inverted output signal of MM20 are OR4
2 is input. The output signal of this OR42 is AND2
1 and becomes the display control signal for state 3. The other circuit configurations are similar to the second embodiment shown in FIG.

That is, in this embodiment, the display 4
blinks for a predetermined time in state 1 (Fig. 12 (1)),
In state 2, the output signal of the MM20 (FIG. 12(2)) is turned on while it is at a high level, and then turned off. Also, in state 3, P
The AND output (Fig. 12 (4)) of the output signal of G30 (Fig. 12 (3)) and the output signal of MM20 (Fig. 12 (2)) and the inversion of the output signal of MM20 (Fig. 12 (2)) Since the OR output (FIG. 12 (6)) with the output (FIG. 12 (5)) controls the switching operation of the switching transistor 11, the display 4 continues to light up after blinking for a predetermined period of time.

FIG. 13 is a circuit diagram of a seventh embodiment of the present invention, and this embodiment is a combination of the third embodiment and the sixth embodiment.

That is, the output terminal of MM20 has AN
One input terminal of D33, the input terminal of inverter 41,
One input terminal of AND40 is connected. Also,
The output terminal of PG30 is the other input terminal of AND40,
An input terminal of DLY31 and one input terminal of OR32 are connected. The output terminal of the inverter 41 is connected to one input terminal of the OR42, and the output terminal of the AND40 is connected to the other input terminal of the OR42. OR42
The output terminal of is connected to one input terminal of an AND 21 that controls the switching operation of the switching transistor 11 in state 3.

The output terminal of DLY31 is connected to the other input terminal of OR32, and the output terminal of OR32 is connected to AN
It is connected to the other input terminal of D33. AND33
The output terminal of is connected to one input terminal of an AND 22 that controls the switching operation of the switching transistor 11 in state 2.

With this configuration, in this embodiment, in state 1, the display 4 blinks for a predetermined period of time (FIG. 14(1)), and in state 2, the output signal of the PG 30 (FIG. 14 (2)) and the signal (Fig. 14 (3)) in which the output signal of the PG30 is delayed by the set time (Fig. 14 (3)), the signal (Fig. 14 (4)) is the output signal of the MM20 (Fig. AND3 only while 14(5)) is at high level.
3 (Fig. 14 (6)), the display 4 is
It blinks for a predetermined time at a duty ratio different from state 1, and then turns off.

In state 3, the output signal of MM20 and PG3
An output signal of the AND of the output signals of 0 (FIG. 14 (7)),
Since the signal (FIG. 14 (9)) obtained by ORing with the inverted signal of MM20 (FIG. 14 (8)) is output from the OR 42, the display 4 blinks for a predetermined period of time and then remains lit. Take.

FIG. 15 is a circuit diagram of an eighth embodiment of the present invention, and this embodiment takes the same display mode as the second embodiment in states 1 and 2, and takes a different display mode in state 3. .

For this reason, in this embodiment, MM2
In addition to one input terminal of AND22, the output terminal of 0 is connected to the input terminal of inverter 51 and one input terminal of OR54, and the output terminal of inverter 51 is connected to DL
It is connected to the input terminal of DLY52, which has a different delay time than Y31. The output terminal of DLY52 is A
Connected to one input terminal of ND53, AND5
The other input terminal of PG30 is connected to the output terminal of PG30. The output terminal of AND53 is connected to the other input terminal of OR54, and the output terminal of OR54 is connected to one input terminal of AND21.

In this embodiment, the display 4 is in state 1.
In state 2, the light blinks for a predetermined period of time and then goes out (FIG. 16(1)), and in state 2, it lights only while the output signal of the MM 20 (FIG. 16(2)) is at a high level and then goes out.

Inverted output signal of MM20 (Fig. 16 (3))
is delayed by the delay time set by DLY52 (Fig. 16 (4)), and the output signal of PG30 (Fig. 16 (5)
) (Figure 16 (6)) and then OR54
You will be asked to enter the information. Therefore, the output signal of OR54 becomes as shown in FIG. 16 (7), and in state 3, this OR
Since the display mode of the display 4 is controlled by the output signal of 54, the display 4 is turned on for a predetermined time, then once turned off, starts blinking after the set time has elapsed, and continues blinking thereafter.

FIG. 17 is a circuit diagram of a ninth embodiment of the present invention. This example is a combination of the third example and the eighth example, and in states 1 and 2, the display form of the third example is used, and in state 3, the display form of the eighth example is used. Take.

For this reason, in this embodiment, state 2
A pulse signal with a duty ratio different from the output signal of PG30 formed by DLY31 and OR32 is used as the input signal of AND22 which outputs the display control signal of the display 4 when the state 3 is reached. As the input signal of AND21 which outputs the signal, MM20, inverter 51, DLY52, PG30, AND53 and OR5
4, which remains at a high level for a predetermined period of time and then blinks.

That is, in state 1, the display 4 blinks for a predetermined period of time (FIG. 18(1)). In state 2, the output signal of PG30 (FIG. 18 (2)) is
is delayed by the time set in (Figure 18 (3)), and OR
At 32, the logical sum with the undelayed signal is taken, and PG3
A pulse signal (FIG. 18(4)) with a duty ratio different from the output signal of 0 is formed. This pulse signal and MM20
The display control signal in state 2 (FIG. 18 (6)) is logically ANDed with the output signal (FIG. 18 (5)) of AN
It is supplied to the base of the switching transistor 11 via D30, 22, and OR23. That is, in state 2, the indicator 4 blinks for a predetermined period of time at a different duty ratio from state 1.

The inverted signal of MM20 (FIG. 18 (7)) is
Delayed by the time set by DLY52 (Fig. 18 (8)
)), AND53 outputs the PG30 output signal (Figure 18 (2)
) is taken (Figure 18 (9)), and M
After being logically summed with the output signal of M20 (FIG. 18 (5)) (FIG. 18 (10)), it is input to one input terminal of AND21. In state 3, this signal becomes the display control signal for the display 4, so the display 4 lights up for a predetermined time, turns off for a set time, and then repeats blinking.

Although circuit examples for realizing each display mode will not be shown below, examples of other display modes will be shown.

FIG. 19 is a first example of another display mode,
The display 4 continues to light up for a predetermined time in state 1 (Fig. 19
(1)), and blinks for a predetermined time in state 2 (Fig. 19 (2)).
, it continues to light up in state 3 (FIG. 19(3)).

FIG. 20 is a second example of another display mode,
The display 4 continues to light up for a predetermined period of time in state 1 (Fig. 20
(1)), and blinks for a predetermined time in state 2 (Fig. 20 (2)).
)), it continues to blink in state 3 (Fig. 20 (3)).

FIG. 21 is a third example of another display mode,
In state 1, the display 4 continues to light up for a predetermined period of time (Fig. 21
(1)), and blinks for a predetermined time in state 2 (Fig. 21(
2)), and in state 3, it continues to light up after blinking for a predetermined period of time (FIG. 21 (3)).

FIG. 22 is a fourth example of another display mode,
The display 4 continues to light up for a predetermined period of time in state 1 (Fig. 22
(1)), and blinks for a predetermined time in state 2 (Fig. 22 (2)).
), in state 3, it lights up for a predetermined period of time, then turns off for a set period of time, and continues blinking after the set period of time has elapsed (Figure 22 (3)).
.

Note that the display mode of the present invention is not limited to the display mode described above, and other display modes may be used.

Further, the circuit configuration for realizing the above display mode is not limited to the above-described circuit configuration, and other circuit configurations may be used.

Further, in the second to ninth embodiments described above, a gate circuit was used to switch the output of the display control signal in state 2 or 3, but it is also possible to switch the output of the display control signal in state 2 or 3. good.

Furthermore, although the display device 4 has been assumed to be a light-emitting display device in the above embodiments, it is not limited to this, and an audio display device such as a buzzer or a chime may be used.

[0085]

Effects of the Invention Since the warning device of the present invention is constructed as described above, it is possible to issue a seatbelt fastening warning and to display whether or not the occupant protection device is malfunctioning using a single display means, thereby reducing the cost and space of the display means. It is possible to save space and reduce the possibility that the driver will misidentify the display means.

Furthermore, since the display means also displays the connection status of the occupant protection device, if there is a failure in the occupant protection device, the display means will definitely indicate that the occupant protection device is not connected. It is possible to prevent the driver from misidentifying the driver.

[Brief explanation of drawings]

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

FIG. 2 is a timing chart showing waveforms of various parts in the first embodiment.

FIG. 3 is a circuit diagram of a second embodiment of the invention.

FIG. 4 is a timing chart showing waveforms of various parts in the second embodiment.

FIG. 5 is a circuit diagram of a third embodiment of the present invention.

FIG. 6 is a timing chart showing waveforms of various parts in the third embodiment.

FIG. 7 is a circuit diagram of a fourth embodiment of the present invention.

FIG. 8 is a timing chart showing the display mode of the fourth embodiment.

FIG. 9 is a circuit diagram of a fifth embodiment of the present invention.

FIG. 10 is a timing chart showing the display mode of the fifth embodiment.

FIG. 11 is a circuit diagram of a sixth embodiment of the present invention.

FIG. 12 is a timing chart showing waveforms of various parts in the sixth embodiment.

FIG. 13 is a circuit diagram of a seventh embodiment of the present invention.

FIG. 14 is a timing chart showing waveforms of various parts in the seventh embodiment.

FIG. 15 is a circuit diagram of an eighth embodiment of the present invention.

FIG. 16 is a timing chart showing waveforms of various parts in the eighth embodiment.

FIG. 17 is a circuit diagram of a ninth embodiment of the present invention.

FIG. 18 is a timing chart showing waveforms of various parts in the ninth embodiment.

FIG. 19 is a timing chart showing a first example of another display mode of the present invention.

FIG. 20 is a timing chart showing a second example of another display mode of the present invention.

FIG. 21 is a timing chart showing a third example of another display mode of the present invention.

FIG. 22 is a timing chart showing a fourth example of another display mode of the present invention.

[Explanation of symbols]

1 Ignition switch 2 Seatbelt warning display device 3 Malfunction alarm display device 4 Display unit 5,6 Terminal 7 Seatbelt alarm circuit 9 Failure detection circuit 12, 13 Comparator 20 Monostable multivibrator 30 Pulse generator 31, 52 Delay circuit

Claims (1)

[Claims] 1. Seatbelt warning means for outputting a warning signal warning that the seatbelt is fastened; failure warning means for detecting a failure of an occupant protection device and outputting a warning signal corresponding to the presence or absence of the failure; In an alarm device comprising at least a display means for displaying an alarm based on an alarm signal output from the seatbelt alarm means, it is determined whether the failure alarm means is connected to the display means or not, and whether the failure alarm means outputs an alarm from the failure alarm means. 1. An alarm device comprising display control means for changing the display mode of the display means in response to an alarm signal.