JPH0314656B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a device for preventing drowsy driving based on the open/closed state of the driver's eyelids, and more particularly to a drowsy driving prevention device that more reliably prevents drowsy driving.

[Technical Background of the Invention and Problems Therewith] In recent years, various devices have been proposed to prevent drowsy driving and improve driving safety. For example, the dozing prevention device disclosed in Japanese Patent Application Laid-Open No. 127198/1983 is one of the devices for this purpose. This anti-drowsiness device uses glasses equipped with a means for transmitting electromagnetic waves to the wearer's eyes and a means for receiving reflected waves from the wearer's eyes, and transmits electromagnetic waves such as infrared rays to the eyelids and cornea of the eyes. Focusing on the fact that the level of reflected waves from the eyelids becomes higher when the waves are transmitted, it detects that the eyelids are closed and if this state continues for a predetermined period of time, it determines that the person is dozing off and issues an alarm. . That is, by making the driver wear glasses related to this dozing prevention device, it is possible to detect dozing off while driving and warn the driver.

By the way, in the case of the dozing prevention device, the dozing state is determined by detecting that the duration of time that the eyelids of the wearer of glasses are closed reaches a predetermined time, as described above. In other words, the device is configured to detect dozing immediately before or after entering a complete dozing state. However, when trying to apply this drowsiness prevention device to detecting drowsiness while driving, it is inappropriate to detect drowsiness immediately before or after entering a complete drowsiness state from the viewpoint of preventing drowsiness while driving. It is necessary to detect dozing at an earlier stage by detecting whether or not there is a risk of dozing off based on the situation.

For this reason, we have focused on the fact that humans tend to blink more frequently than when they are awake in order to counteract sleepiness, as a prelude to the onset of a closed-eye state in which the eyelids are closed due to drowsiness as the level of alertness decreases. When the number of blinks per hour exceeds a predetermined number, it is conceivable to issue a warning in advance, indicating that there is a risk of dozing off. However, it is known that there are individual differences in the number of blinks associated with this decrease in alertness, and the standard number of times for determining whether there is a risk of falling asleep based on the increase in the number of blinks is not suitable for making accurate judgments. It is not appropriate to determine it unambiguously, and there has been a strong desire for an appropriate means of determining the number of times as a criterion.

[Object of the Invention] The present invention has been made in view of the above, and has the object of: detecting drowsiness early in a device for preventing drowsiness while driving based on the opening/closing state of the driver's eyelids; To provide a drowsy driving prevention device capable of accurately preventing drowsy driving even if the driver changes.

[Summary of the invention] In order to achieve the above object, this invention
As shown in the figure, the drowsy driving prevention device prevents drowsy driving based on the opening/closing state of the driver's eyelids, and the setting means 1 counts the number of blinks per unit time in a predetermined period of time immediately after the device starts operating. Setting a reference number of blinks per unit time, comparing the number of blinks per unit time measured by the measuring means 3 with the reference number in the drowsy driving detection means 5, and detecting drowsy driving based on the comparison result. The gist is:

[Embodiments of the Invention] Examples of the invention will be described below with reference to the drawings.

FIG. 2 is a circuit diagram of a drowsy driving prevention device according to an embodiment of the present invention. This drowsy driving prevention device is provided near the bottom part 1a of the frame that holds the lenses of the glasses 1 shown in FIG.
A wave transmitting/receiving unit 3 that transmits an electromagnetic wave of a specific wavelength near infrared light to the wearer's eyes and receives a reflected wave from the wearer's eyes, and a wave transmitting/receiving unit 3 that is provided on one vine 1b of the glasses 1. a telemeter transmission signal 5, which is housed in a small box, and has a telemeter function for driving and controlling the wave transmitting/receiving section 3, receiving a signal from the wave transmitting/receiving section 3, and further transmitting the received signal; and glasses 1.
For example, it may be housed in a suitable case and installed at a suitable place in the vehicle, or it may be portable and stored in the driver's pocket, etc., and the telemeter transmitter 5 may be The control unit 7 receives a signal and detects dozing by the driver who wears the glasses 1 based on the signal.

The wave transmitting/receiving unit 3 includes a wave transmitting means 9 that transmits electromagnetic waves of a specific wavelength to the eyes of the wearer of the glasses 1, and this wave transmitting means 9.
The wavelength band of the electromagnetic waves transmitted from the wave transmitting means 9 is different from that of the first wave receiving means 11 which receives reflected waves from the cornea or eyelids of the wearer's eyes with respect to the electromagnetic waves of a specific wavelength transmitted from the first wave receiving means 11. It has a second wave receiving means 13 that receives electromagnetic waves in a wavelength band. The wave transmitting means 9 includes a light emitting diode 15 that outputs an electromagnetic wave in a wavelength band near near-infrared light, and a transmitting narrowband transmission filter 17 that passes only the electromagnetic wave of the specific wavelength among the output electromagnetic waves. It is. 1st
The wave receiving means 11 includes a receiving narrowband transmission filter 19 that passes only the electromagnetic waves of a specific wavelength received from the wave transmitting means 9, and a receiving narrowband transmission filter 19 that passes the electromagnetic waves that have passed through the receiving narrowband transmission filter 19. This configuration includes a light receiving element 23 that receives light and converts it into an electrical signal.
The second wave receiving means 13 includes a wave receiving transmission filter 21 that receives electromagnetic waves (for example, headlamp light) in a wavelength band different from the wavelength band of the specific wavelength transmitted from the wave transmitting means 9, and This configuration includes a light receiving element 25 that receives electromagnetic waves that have passed through the transmission filter 21 and converts them into electrical signals. Note that the light receiving elements 23 and 25 are composed of, for example, phototransistors.

The telemeter transmitter 5 includes the light emitting diode 1
5 and drives and controls the light emitting diode; the light receiving element 23 of the first wave receiving means 11 and the light receiving element 25 of the second wave receiving means 13;
These light receiving elements 23 and 25 are connected to
amplifiers 31 and 33 that amplify the light reception signal from the
A telemeter transmission circuit 3 transmits the received light signal amplified by these amplifiers 31 and 33 as a wireless signal.
5, 37.

The control unit 7 includes telemeter transmission circuits 35 and 37
telemeter receiving circuits 41 and 43 which respectively receive transmission signals from the telemeter receiving circuit 4;
Comparators 45 and 47 whose outputs from 1 and 43 are respectively connected to the inverting input terminal (-)
and resistors 49, 51 and 53, which are connected in series between the power supply voltage Vcc and the ground and divide the power supply voltage Vcc and supply a reference voltage to the ratio inverting input terminals (+) of the comparators 45 and 47, respectively.
55, a first differentiation circuit 57 which differentiates the output signal of the comparator 45, detects the rising edge of the output signal, and outputs a rising signal B corresponding to the rising signal; A second differentiating circuit 59 detects the falling edge of the output signal and outputs a falling signal C corresponding to the falling signal, a rising signal B from the first differentiating circuit 57, and a rising signal B from the second differentiating circuit 59. A microcomputer 6 receives the falling signal C and the output signal D from the comparator 47 and detects dozing by the driver who wears the glasses 1 based on these signals.
1, a sensor 63 consisting of, for example, a manual switch, etc., which supplies a signal to the microcomputer 61 to command the start of operation of this device, and a sensor 63, which is driven by an output signal from the microcomputer 61 and issues an alarm, such as a buzzer, melody IC, etc. This configuration includes alarm devices 65 and 67. Note that two alarm devices, devices 65 and 67, are provided and used depending on the state of dozing, but one device may be used.
Further, the sensor 63 may be configured to input a vehicle speed signal taken out from the vehicle to the microcomputer 61.

The comparator 45 focuses on the level of the reference signal supplied to the non-inverting input terminal, that is, the level of the electromagnetic wave transmitted from the wave transmitting means 9 reflected by the eyelid is higher than the level of the reflected wave by the cornea. Since the setting is made so that this difference becomes clear, it is detected that the received light signal, that is, the output signal of the telemeter receiving circuit 41, is at a higher level than the reference signal, that is, that the received light signal is a wave reflected by the eyelid. Then, a high level (H) signal is output. As described above, this high level signal is differentiated by the first differentiating circuit 57 and the second differentiating circuit 59, and the first differentiating circuit 57 produces a rising signal B indicating the point in time when the eyelids are closed, and a second differentiating circuit 59. The differential circuit 59 supplies a falling signal C indicating the point at which the eyelids are opened to the microcomputer 61, and the microcomputer 61 measures the time the eyelids are closed, the number of times the eye blinks, etc. based on these signals. , glasses 1
It is determined whether or not the driver wearing the driver is drowsy while driving, and if drowsiness is detected, an alarm is issued using the alarm devices 65 and 67.

The comparator 47 determines whether the level of the reference signal supplied to the non-inverting input terminal is equal to the level of near-infrared electromagnetic waves in the vicinity of the wave transmitting/receiving section 3, which is transmitted from the wave transmitting means 9 by the headlights of an oncoming vehicle. It is set to be able to determine whether or not the level of the electromagnetic waves reflected by the cornea or eyelids of the driver's eyes is high enough to affect the level of the electromagnetic waves reflected by the cornea or eyelids of the driver's eyes. Alternatively, it is detected that the level is high enough to affect the waves reflected by the eyelids, and a high level (H) signal is supplied to the microcomputer 61. While the microcomputer 61 is being supplied with this high-level output signal D, the rising signal B and the falling signal C are supplied from the comparator 45 via the first differentiating circuit 57 and the second differentiating circuit 59. The system also ignores these signals, assuming that they are caused by extraneous light from the headlights of oncoming vehicles. Note that instead of providing the circuit from the second wave receiving means 13 to the comparator 47 described above, a vapor-deposited film of a filter may be coated on the lens surface of the glasses 1 in order to block external electromagnetic waves in the near-infrared region. good.

Next, the operation of the drowsy driving prevention device shown in FIG. 2 will be explained using the flowcharts shown in FIGS. 4 and 5.

The flowcharts in FIGS. 4 and 5 show the initial processing flow (steps 110 to 120) for determining whether 10 minutes have passed since the device was activated, and 1, which is the unit time.
A blink count counting flow (steps 130 to 180) in which a counter counts the number of blinks per minute, and a timer 2 measures when the eyelids are closed for a predetermined period of time, for example, 3 seconds or more, and activates the alarm device 67. Eye-closing time measurement flow (steps 190 to 220)
and the first 10 to determine the reference blink number.
A blink count memory flow (steps 230 to 260) that repeatedly stores the number of blinks per minute counted by a minute counter, and a reference value determination flow that determines a reference value for the blink count from the memorized blink count (steps 300 and 310). and a dozing detection flow (steps 400 to 440) in which dozing is detected by comparing the number of blinks counted by a counter with a reference value after 10 minutes have elapsed, and the alarm device 65 is activated.

First, the microcomputer 61 uses the sensor 63
A check is made to see if a command signal A for starting the device has been input (step 110). If command signal A is not input, the timer and reference value are reset and the process returns to the original state (step 115). If the command signal A has been input, the process advances to step 120 to check whether 10 minutes have elapsed since the command signal A was input. This 10-minute check is to store the data on the number of blinks for determining the reference value for the number of blinks in the last 10 minutes, as described above, and is performed at least 10 times after starting the device in this way.
Most people do not doze off for about a minute and perform relatively normal movements, so by counting the number of blinks in the last 10 minutes and calculating the average, it is possible to obtain a relatively accurate number of blinks. This allows a reference value to be determined.

In other words, if 10 minutes have not passed, the step
Proceeding to steps 130 onwards, a one-minute timer for unit time is set, and it is checked whether one minute has elapsed (steps 130-140). If one minute has not elapsed, it is checked whether the output signal D from the comparator 47 is being input, that is, whether an external signal such as the headlights of an oncoming vehicle is being input as described above. In this case, it is impossible to measure blinking, etc., and the process returns to the beginning (step 150). If there is no external noise, check whether or not a rising signal B indicating the time when the eyelids are closed is input, and if it is input, set timer 2 and measure the time the eyelids are closed. At the same time, a counter is incremented to count the number of blinks (steps 160 to 180).

Next, a check is made to see if a falling signal C indicating the point at which the eyelids are opened is input, and if a falling signal C is input, the contents of the timer 2 are checked to see if 3 seconds or more have passed. Check whether or not (steps 190, 200). If the content of timer 2 indicates 3 seconds or more, it can be determined that the eyelids are closed due to dozing, and therefore alarm 2, that is, the alarm device 67 is activated to alert the driver (step 210). However, if 3 seconds or more have not elapsed, timer 2 is reset and the process returns to the original state (step 220).

Furthermore, in step 140, if one minute has elapsed, the process proceeds to step 230, where it is checked whether or not a reference value for the number of blinks for determining dozing has been determined.
After resetting the one-minute timer and storing the contents of the counter that counted the number of blinks, the counter is reset and the process returns to the original state. This routine is 10
This is repeated until a minute has elapsed, and the number of blinks is measured and memorized (steps 240 to 260).

When 10 minutes have elapsed, the process proceeds from step 120 to step 300, where it is checked whether or not a reference value for the number of blinks for determining dozing has been determined. Calculate the average value N and standard deviation σ from the number of blinks, and use these values to determine the standard value (=N+2σ)
is calculated (step 310). In this way, this reference value has a range by adding or subtracting a value twice the standard deviation σ to the average value N. Once the reference value for the number of blinks is determined, the process returns to step 130 and the number of blinks per minute is measured thereafter.

As described above, after 10 minutes have passed and the reference value for the number of blinks has been determined, the process returns to step 130 and counts the number of blinks. Each time the counting is completed, the process proceeds from step 140 to step 400 via step 230, and the contents of the counter that counted the number of blinks are compared with the reference value. The number of blinks counted by the counter is subject to deviation as described above.
If it is within the reference value having a width of 2σ, it can be determined that there is no problem and that there is no dozing off, so the counter and the one-minute timer are reset and the process returns to the original state (steps 430 and 440). However, if the number of blinks counted by the counter is not within the reference value having a deviation width of 2σ as described above, it is assumed that the driver wearing glasses 1 is dozing off, so step 410 is performed. In step 420, if such dozing is detected twice or more, alarm 1, that is, the alarm device 65 is activated to issue a warning to the driver (step 420).

In the above reference value, an alarm is issued when a dozing state is detected twice in step 420, but this is to reduce the possibility of issuing a warning to the driver by mistake, and is limited to two times. However, when considering the safety of driving in case of falling asleep, it is considered possible to issue a warning only once.

Further, in the above embodiment, the telemeter transmitting circuits 35, 37 and the telemeter receiving circuit 41,
43 to transmit data to the control unit 7 wirelessly has the advantage of reducing the weight of the device installed in the glasses 1 and also reducing the burden on the power supply battery, but this is not necessarily limited to this. It is not necessary to install it, but it may be installed in the glasses 1, or it may be connected by wire.

[Effects of the Invention] As explained above, according to the present invention, a reference value for the number of blinks is set for determining a decrease in the level of alertness based on the number of blinks of the individual driver when he or she is awake, which is counted immediately after the device starts operating. Since drowsy driving is detected by comparing this reference value with the number of blinks measured thereafter, drowsy driving can be detected early and accurately even if the driver changes.

[Brief explanation of drawings]

Fig. 1 is a diagram corresponding to the claims of this invention, Fig. 2 is a circuit diagram of a drowsy driving prevention device showing one embodiment of the invention, and Fig. 3 is a perspective view of glasses equipped with a part of the device shown in Fig. 2. , 4 and 5 are flowcharts showing the operation of the drowsy driving prevention device of FIG. 2. 1...Setting means, 3...Measuring means, 5...Drowsy driving detection means.

Claims (1)

[Claims] 1 A drowsy driving prevention device that prevents drowsy driving based on the open/closed state of the driver's eyelids, which calculates the standard number of blinks per unit time by counting the number of blinks per unit time during a predetermined period immediately after the device starts operating. The vehicle is characterized by comprising a setting means for setting, a measuring means for measuring the number of blinks per unit time, and a drowsy driving detection means for detecting drowsy driving based on a comparison between the measured number of blinks and the reference number of blinks. Drowsy driving prevention device.