JPH02234849A - Winking detecting device - Google Patents

Abstract

PURPOSE:To enable the precise detection of winking of an objective person of test by detecting the winking from the difference in tone between eye opening state and eye closing state by means of a tone detecting means, and also correcting the tone signal with the environmental light significantly affecting the tone judgment. CONSTITUTION:When the device is practiced in a doze preventing device for automobile, a tone sensor 1 provided with two photodiodes having respective peaks of light receiving sensitivity in different light wavelength ranges is provided on the lens frame of glasses 7, whereby the tone of the eyes of a wearing person is detected. Similarly, an illumination sensor 2 as an environmental light intensity detecting means for detecting the illumination of the skin in the lower part of the eye is provided on the lens frame of the glasses 7. From the outputs of these sensors 1, 2, the winking state is detected in a transmitter part 5 on the basis of a tone signal corrected by the illumination signal, and the wink signal is transmitted to a receiver part 6. In the receiver part 6, the frequency of winking per unit time is measured, and when the frequency of winking is outside a determined range, a buzzer is operated to give an alarm.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an eye blink detection device useful for detecting the physiological state of a test subject, such as dozing off or eye fatigue. It is commonly used in devices that prevent drowsy driving based on the following.

[Conventional technology]

Conventionally, as this type of device, for example, Japanese Patent Application Laid-Open No. 59-127
No. 198, electromagnetic waves such as infrared rays are directed to the eyelids using glasses equipped with means for transmitting electromagnetic waves to the wearer's eyes and means for receiving reflected waves from the wearer's eyes. Some devices detect the open/closed state of the eyelids by focusing on the fact that when the waves are transmitted to the cornea of the eye, the level of the reflected waves from the eyelids becomes higher. Note that a light emitting element that emits near-infrared light is used as a means for transmitting electromagnetic waves to the wearer's eyes.

[Problem to be solved by the invention]

However, since this device is specially equipped with a means for transmitting electromagnetic waves such as infrared rays to the wearer's eyes, there are limits to power saving of the power source and miniaturization and weight reduction of the device.

Therefore, the present inventors focused on detecting blinking based on changes in the ambient light that is diffusely reflected from the eyes using ambient light as a light source, that is, changes in color tone in the eyes. However, according to experiments conducted by the present inventors, it has been found that this method is greatly affected by environmental light as a light source in color tone discrimination.

The present invention has been made in view of the above points, and an object of the present invention is to provide an eye blink detection device that does not include a light emitting element and can accurately detect eye blinks even under the influence of environmental light.

[Means to solve the problem]

In order to achieve the above-mentioned object, the present invention includes a color tone detecting means provided in a frame of eyeglasses for detecting the color tone of the wearer's eyes and generating a color tone signal; Ambient light intensity detection means detects the intensity of ambient light in the vicinity of the detection area of the color tone detection means and generates an ambient light signal; A technical means is adopted in which the wearer comprises a blinking detection means for correcting the signal and detecting the blinking state of the wearer based on the corrected color tone signal.

[Operation] The color tone detection means detects the color tone of the wearer's eyes and generates a color tone signal, and the environmental light intensity detection means detects the intensity of environmental light in the vicinity of the detection area of the color tone detection means and generates an environmental light signal. occurs. The blink detection means corrects the color tone signal using the ambient light signal and detects the blink state of the wearer based on the corrected color tone signal.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention shown in the drawings will be described. 1st
The figure is a system configuration diagram showing an embodiment of the present invention in a dozing prevention device. ■ indicates different optical wavelength ranges (850ns on the high side, 600ns on the low side) as shown in Figure 2.
This is a color tone sensor serving as a color tone detection means, which includes two built-in photodiodes, each having a peak of light receiving sensitivity at m). Since there is a one-to-one relationship between the wavelength of the light incident on the color sensor 1 and the current ratio of the currents flowing through the two photodiodes, it is possible to determine the color by determining this current ratio. can. Further, the color tone sensor 1 is installed in the lens frame of the glasses 7, and detects the color tone of the wearer's eyes. 2 is an illuminance sensor as an ambient light intensity detection means;
Like the color tone sensor 1, it is installed in the lens frame of the glasses 7, and has a detection area near the detection area of the color tone sensor. 1st
In the figure, the illuminance of the skin below the eyes is detected.

Furthermore, the illuminance sensor 2 has a peak luminance near a light wavelength of 600 nm. Reference numerals 3 and 4 are electrodes disposed along the inside of the left and right frames (skin contact side) of the glasses 7, respectively, for detecting the skin resistance of the living body, and made of a conductive material.

5 is a receiving unit which performs each detection process of the wearing of glasses 7 and the blinking of the living body based on the signals from the color tone sensor 1, the illuminance sensor 2, and the electrodes 3 and 4, and receives the blinking signal using weak radio, which will be described later. This is a transmitter that transmits data to 6. This transmitter 5 is attached to the frame of eyeglasses 7. 6 is the receiving section,
The number of blinks per unit time is measured based on the blink signal from the transmitter 5, and if the number of blinks is not within a predetermined range, a buzzer or the like is used to alert the wearer. Furthermore, since the receiving section 6 is small, it can be placed in a jacket pocket or the like. Reference numerals 52 and 61 are power switches for the transmitter and receiver, respectively.

Next, an overview of the operation of this embodiment will be explained using FIG.
When the power switches 52 and 61 of the transmitter 5 and the receiver 6 are turned on, the receiver 6 immediately starts operating. On the other hand, the transmitter 5 measures the resistance (skin resistance) between the electrodes 3 and 4, and when the resistance becomes a predetermined value or less, that is, when the glasses 7 are worn, the color tone sensor 1, the illuminance sensor 2 and a processing circuit built into the transmitter 5, which will be described later, are supplied with power. Then, a blinking signal corresponding to the blinking of the living body is created by the processing circuit built in the transmitting section, and the receiving section 6
Send to. As described above, the receiving unit 6 calculates the number of blinks per unit time, and uses the calculated value to notify the wearer of dozing off.

As described above, since blink detection is started after the eyeglasses 7 are worn, erroneous detection caused by putting on and taking off the eyeglasses 7 and unnecessary operation can be prevented, and power consumption can be further reduced.

Next, FIG. 2 is a circuit diagram of the transmitter 5 shown in FIG. 1.

In FIG. 2, reference numeral 5 is a battery which is a power supply source for the internal circuit of the transmitter 5. 52 is a power switch of the transmitter 5. 53 is a power switch 520N that controls the voltage of the battery 51.
This is a battery voltage monitoring circuit that constantly monitors the battery voltage and, when the voltage drops below a predetermined voltage, makes the speaker 54 sound to notify the wearer of the battery voltage drop.

55 measures the inter-electrode resistance of the electrodes 3.4 attached to the left and right frames of the glasses 7, and if the inter-electrode resistance is infinite, the output voltage +■ is cut off, and if it is less than several hundred MΩ, it is output. This is a glasses wearing detection circuit that outputs a voltage +■. The outputs +■ of the glasses wearing detection circuit 55 are 56, 57, which will be described later.
This is the power supply for each circuit of 58 and 59.

56 calculates the logarithm of the current ratio of the currents flowing through the two photodiodes by amplifying the photocurrents of the two photodiodes of the color tone sensor 1 with a log amplifier and subtracting the two photocurrents with a differential amplifier. This is a color tone processing circuit that outputs a color tone signal a corresponding to the light wavelength. Since the color tone sensor 1 is attached to the eyeglass frame and detects the color tone of the wearer's eyes, the color tone signal a includes color tone changes caused by the wearer's blinking, as shown in FIG.

57 amplifies the illuminance signal near the eyes output from the illuminance sensor 2, processes it with a low-pass filter, and outputs it as an illuminance correction signal b, and also detects that the illuminance correction signal b changes by a predetermined value or more per unit time. In this case, the illuminance processing circuit as a prohibiting means outputs an illuminance change signal d that prohibits the output of an envelope detection signal g, which will be described later, for a predetermined period of time by cooperation of a differentiator, a first comparator, and a one-shot multi-by-break. be. Further, in this circuit, even when the illuminance is not above a predetermined value, an illuminance reduction signal e that prohibits the output of the envelope detection signal g is outputted in cooperation with the minimum operating illuminance setting resistor 571 and the second comparator.

Reference numeral 58 denotes a blink processing circuit as a blink detection means that outputs a blink signal h corresponding to a blink based on the output signals from the color tone processing circuit 56 and the illuminance processing circuit 57 by a method described later.

59 is a radio circuit that frequency modulates the blink signal h from the blink processing circuit 58 and transmits the blink signal to the receiving unit 6 using weak radio as a medium.

The operation of each of the processing circuits 56 to 58 of the transmitter 5 shown in FIG. 2, that is, the process of creating the blink signal h, will be explained using each processed signal. Note that FIG. 3 is a time series characteristic diagram of a typical processed signal.

First, from time t0 to time t1, the illuminance near the face centering on the eyes is extremely low. In this case, no change corresponding to blinking is observed in the color tone signal a. Therefore, the illuminance correction signal b in the second comparator and the operating minimum illuminance setting resistor 5
By comparison with the operating minimum illuminance voltage C set by 71, the signal level of the illuminance reduction signal e becomes "L"',
Output of the blink signal h is prohibited.

Next, from time L to t t', the illuminance around the eyes and the vicinity of the face gradually becomes brighter and becomes constant at a certain illuminance. At this time, the signal level of the illuminance reduction signal e is ``
It is H''.

As the illuminance increases, the color tone signal a becomes able to better detect color tone changes near the eyes. In Figure 3, the maximum value is the state when the eyes are closed. However, in this case, there are changes in the illuminance around the face, centering on the eyes.
There are fluctuations in the DC component (baseline component). In order to prevent false detection due to fluctuations in the DC component, the addition/subtraction amplifier within the blink processing circuit performs addition/subtraction processing on the color tone signal a and the illuminance correction signal b according to the increase/decrease in illuminance to correct fluctuations in the DC component. The corrected signal f is taken as the corrected signal f. Next, the envelope line detector inputs this correction signal f, obtains an envelope signal i (see Figure 3) through a filter with a large time constant, and compares the correction signal r with the envelope signal i, i.e. By performing envelope detection, fluctuations in the DC component according to the color tone signal a are removed due to gradual changes in illuminance, and an envelope detection signal g corresponding only to blinking is output. In this case, the envelope detection signal g is output as the blink signal h. From the next time t8 to t3, the illuminance of the face centered on the eyes changes rapidly. 2. Due to drastic changes in illuminance, a spike-like signal remains in the correction signal f that cannot be corrected only by correcting the DC component. The envelope signal i obtained by smoothing the correction signal f has a large time constant and cannot follow the spike-like signal, so no influence can be seen. However, when comparing the correction signal r and the envelope signal i, As shown in FIG. 3, the envelope detection signal g obtained is affected by the magnitude of the spike-like signal of the correction signal f.

Therefore, in response to sudden changes in illuminance, the illuminance processing circuit 57
The differentiator, the first comparator, and the one-shot multi-by-break determine whether there is a change in illuminance of more than a predetermined value per unit time, and if there is, the signal level is set to "L" for a predetermined period of time from the time of the change in illuminance. An illuminance change signal d is created, and noise associated with a sudden change in illuminance included in the envelope detection signal g is prohibited from being output to the blink signal h. Therefore, as shown in FIG. 3, the blink signal h
is not affected by rapid changes in illuminance.

As described above, the blink signal h is obtained, and the transmitter 5
The signal is input to a built-in wireless circuit 59.

Note that in the above embodiments, fluctuations in the DC component due to changes in illuminance are corrected, but the magnitude of the blink component included in the color tone signal a may be corrected from the color tone signal a and the illuminance correction signal b. ．． Further, the color tone detection means used in the above embodiments was a color tone sensor that had two built-in light-receiving elements with light-receiving sensitivities in different light growth regions, but the sensor is not limited to this, and can detect color tone changes. Anything is fine. In the above embodiment, the present invention is used in a dozing prevention device, but the present invention is not limited to this. For example, a device that controls the humidity around a living body by utilizing the change in the number of blinks due to the dryness and humidity of the eyeballs, etc. It can also be implemented. [Effect of the invention] As stated above, in the invention set forth in claim 1,
The color tone detection means detects blinking based on the difference in color tone between the eyes open and closed eyes, and also compensates for it using environmental light, which has a large effect on color tone discrimination.Therefore, there is no need to provide a special light emitting element, and the blinking can be detected by the wearer. This has the excellent effect of accurately detecting the blinking of the eyes.

Furthermore, in the invention as claimed in claim 2, since the detection of eye blinks is prohibited when the change in the intensity of the environmental light is above a predetermined level, it is possible to eliminate false detection when the environmental light changes. It has a positive effect.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment in which the present invention is applied to a dozing prevention device, Fig. 2 is a detailed circuit diagram of the transmitting section in Fig. 1, and Fig. 3 is a signal waveform diagram of each part in Fig. 2. It is. 1... Color tone sensor, 2... Illuminance sensor. 5... Transmitting section, 6... Receiving section, 7... Glasses. 56... Color tone processing circuit, 57... Illuminance processing circuit, 58... Blink processing circuit. Representative Patent Attorney Takashi Okabe (and 1 other person) Figure

Claims (2)

[Claims] (1) A color tone detection means provided on the frame of the glasses to detect the color tone of the wearer's eyes and generate a color tone signal; Ambient light intensity detecting means detects the intensity of ambient light and generates an ambient light signal, and the color tone signal from the color tone detecting means is corrected by the ambient light signal from the ambient light intensity detecting means, and the corrected color tone is An eye blink detection device comprising: blink detection means for detecting a blink state of the wearer based on a signal. (2) The invention further comprises a prohibiting means for detecting a change in the environmental light signal from the environmental light intensity detecting means and prohibiting the blink detecting means from detecting blinking when the change is greater than a predetermined level. 1. The blink detection device according to 1.