Safety Assurance System for Road Vehicles

Field of the Invention

This invention relates to a safety assurance system for use in a road vehicle and, more particularly, to such a system adapted to make an alarm so as to bring the driver to his senses if the driver falls into a doze or fatigued condition during driving the vehicle.

Description of the Prior Art

Such safety assurance systems have already been proposed which are adapted to give an alarm in order to bring the driver to his senses if the driver falls into a doze or fatigued condition during driving a road vehicle. One difficulty with such conventional safety assurance systems is that their arousing effect becomes too low after long alarming to prevent the driver from falling again into a doze. In addition, the driver can reset the alarm and completely invalidate the alarming without his senses.

It is therefore one object of the present invention to provide an improved safety assurance system for use in road vehicles which is free from the above described disadvantages found in conventional systems.

The present invention will be described in greater detail by reference to the following description taken in connection with the accompanying drawings, in which:

FIG. 1 is a block diagram showing one embodiment of the safety assurance system made in accordance with the present invention,

FIGS. 2 to 4 are block diagrams showing several additional embodiments of the present invention; and

FIG. 5 is a timing chart used in explaining the operation of the safety assurance system of the present invention.

Referring now to FIG. 1, there is illustrated one embodiment of a safety assurance system made in accordance with the present invention. The safety assurance system is illustrated as including a decision circuit 10 which is adapted to make a decision whether or not the driver is in a doze or fatigued condition in accordance with vehicle running conditions. If there is any driver's doze or fatigued condition, the decision circuit 10 provides a warning signal a at its output. An example of appropriate decision circuits that may be used is shown and described in U.S. Pat. No. 3,877,541 issued on Apr. 15, 1975 is adapted to detect a driver's doze or fatigued condition in accordance with the oscillations of the steering wheel of a vehicle.

The output of the decision circuit 10 is coupled to first alarm means 12 and also to second alarm means 14. The first alarm means 12 is for urging the driver to rest from driving by giving various audible or visible signals, such as sounding a buzzer, flashing a light, etc. The second alarm means 14 is for bringing the driver to his senses by blowing a pulsated air stream from an air-conditioner to the driver, sounding a buzzer, etc.

The safety assurance system also includes a sensor 16 which is adapted to determine whether the road vehicle runs or rests. The sensor 16 provides at its output a run signal b when the road vehicle is running. The sensor 16 may be arranged to provide a run signal in accordance with a signal from a vehicle speed sensor or a tape switch set on the dashboard. The output of the sensor 16 is coupled to the input of an inverter 18. The output of the inverter 18 is connected to the reset terminal of the first alarm means 12 and also to one input of an OR gate 20, the output of which is coupled to the reset terminal of the second alarm means 14. The other input of the OR gate 20 is connected toareset switch 22 which is manually operated, by the driver, to provide a reset signal c through the OR gate 20 to the reset terminal of the second alarm means 14 if there is a need to reset the second alarm means 14.

The operation of the safety assurance system of the present invention will now be described with reference to the timing chart of FIG. 5.

When the driver drives the road vehicle in a doze or fatigued condition, the decision circuit 10 generates a warning signal a, which is shown as a high level in waveform 10a of FIG. 5, causing the first and second alarm means 12 and 14 to start giving an alarm, as seen in waveforms 12a and 14a of FIG. 5. If the driver comes into his senses by the alarm and operates the reset switch 22, a reset signal c, which is shown as a high level in waveform 22a of FIG. 5, is applied through the OR gate 20 to the reset terminal of the second alarm means 14. This resets the second alarm means 14, as seen in waveform 14a of FIG. 5, while the first alarm means 12 remains making an alarm, as seen in waveform 12a of FIG. 5, until the driver brings the road vehicle to rest.

If the road vehicle rests, then the sensor 16 stops the generation of the run signal b, which is shown as a high level is waveform 16a of FIG. 5, and the inverter 18 provides a rest signal b, which is shown as a high level in waveform 18a of FIG. 5, directly to the first alarm means 12 which thereby is reset, as seen in waveform 12a of FIG. 5, and also through the OR gate 20 to the second alarm means 14 which thereby is reset if it is still in operation.

If the driver continues driving the road vehicle in spite of the alarm, then the decision circuit 10 provides an additional warning signal a, as seen in waveform 10a of FIG. 5, to the second alarm means 14 which thereby starts making an alarm again, as seen in waveform 14a of FIG. 5. The first alarm means 12 gives the alarm continuously, as seen in waveform 12a of FIG. 5.

As shown in FIG. 1, a delay circuit 24 may be provided between the first alarm means 12 and the decision circuit 10 for delaying the start of operation of the first alarm means 12 a predetermined time with respect to the start of operation of the second alarm means 14. The delay circuit 24 is optional.

Referring to FIG. 2, there is illustrated a second embodiment of the present invention which is substantially similar to the first embodiment except that an additional circuit is provided for intensifying the alarm provided by the first alarm means 12 in accordance with the time elapsed after the start of generation of the alarm in order to urge the driver to rest from driving with higher reliability.

The circuit includes an astable multivibrator 32 which has an input from the decision circuit 10 and a reset terminal connected to the output of the inverter 18. The output of the astable multivibrator 32 is connected to the input of an integrating circuit 34 which has a reset terminal connected to the output of the inverter 18. The integrator circuit 34 integrates the signal from the astable multivibrator 32 with time. The integrated signal is coupled to the input of the first alarm means 12.

It can be seen from waveform 34a of FIG. 5 that the output of the integrating circuit 34 increases with the time lapse after the decision circuit 10 provides a warning signal a first. For example, if the first alarm means 12 utilizes a buzzer, this increases the volume of the buzzer sound with time so as to strongly urge the driver to rest from driving.

When the driver brings the road vehicle to rest, the sensor 16 stops the generation of the run signal b and the inverter 18 provides a rest signal b, as seen in waveform 18a of FIG. 5, to render the astable multivibrator 32 out of operation and also reset the integrating circuit 34, thereby stopping the operation of the first alarm means 12.

Referring to FIG. 3, there is illustrated a third embodiment of the present invention which is substantially similar to the first embodiment except that a counter 36 is provided prior to the first alarm means 12 for intensifying the alarm provided by the first alarm means 12 in accordance with the accumulative frequency of generation of warning signals a.

The counter 36 has an input from the decision circuit 10 and counts the number of warning signals a produced by the decision circuit 10. The counter 36 provides, to the first alarm means 12, an output signal which corresponds to the count stored in the counter 36 and thus increases by a step each time a warning signal a occurs, as seen in waveform 36a of FIG. 5. As a result, the alarm provided by the first alarm means 12 increases in steps in accordance with the accmulative frequency of production of warning signals a. For example, if the first alarm means 12 utilizes a buzzer, the volume of the buzzer sound increases in steps as the accumulative frequency of occurrence of warning signals a increases.

The counter 36 has its reset terminal connected to the output of the inverter 18. When the driver brings the road vehicle to rest, the sensor 16 stops generating the run signal b, as seen in waveform 16a of FIG. 5, and the inverter 18 starts providing a rest signal b, as seen in waveform 18a of FIG. 5, to the counter 36 and also through the OR gate 20 to the second alarm means 14. As a result, the counter 36 is reset, as seen in waveform 36a of FIG. 5, to render the first alarm means 12 imoperative, as seen in waveform 12a of FIG. 5, and also the second alarm means 14 is reset, as seen in waveform 14a of FIG. 5.

Referring to FIG. 4, there is illustrated a fourth embodiment of the present invention which is substantially similar to the first embodiment except that the combination of an astable multivibrator 32 and an integrating circuit 34 such as one described in connection with the second embodiment and a counter 36 such as one described in connection with the third embodiment is connected through an adder 38 to the first alarm means 12. With this embodiment, the first alarm means 12 receives, from the adder 38, a signal, as seen in waveform 38a of FIG. 5, which corresponds to the sum of the output signal from the integrating circuit 34, as seen in waveform 34a of FIG. 5, and the output signal from the counter 36, as seen in waveform 36a of FIG. 5.

Accordingly, the alarm produced by the first alarm means 12 is intensified in accordance with the time lapse and also with the accumulative frequency of occurrence of warning signals a. That is, the first alarm means 12 starts giving an alarm at the time when the first warning signal a is generated by the decision circuit 10 and increases the intensity of the alarm steplessly with time. When the second warning signal a occurs, the intensity of the alarm further increases in a step and thereafter increases steplessly with time. Such an alarm continues until the driver brings the road vehicle to rest.

The operation of the other components will be apparent from the foregoing and will not be described further.

The above described safety assurance system of the present invention includes first alarm means adapted to continue making an alarm until the driver bring the road vehicle to rest and second alarm means adapted to be reset by the driver. The driver is brought to his senses by the second alarm means and urged to rest from driving by the first alarm means. This is highly effective to improve the safety of driving.

The invention also enables the driver to be urged to rest from driving with higher reliability by increasing the intensity of the alarm made by the first alarm means in accordance with the time lapse after the first warning signal occurs and/or with the accumulative frequency of occurrence of warning signals.

It is to be noted that the decision circuit 10 may be removed and replaced with a manually operable switch adapted to be turned on to provide a warning signal where necessary.

While the present invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, it is intended to embrace all alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.