Drowsiness detecting apparatus and method

• US 20060038689A1
• Filed: 06/23/2005
• Published: 02/23/2006
• Est. Priority Date: 08/23/2004
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Yanai, Kenichi, Nanba, Shinji, Ikegami, Tatsuya
• Granted Patent: US 7,397,382 B2
• Time in Patent Office: Days
• US Class Current: 340/575
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/03 Detecting, measuring or recording fluid pressure within the body other than blood pressure, e.g. cerebral pressure; Measuring pressure in body tissues or organs A61B5/205 takes precedence
• CPC Class Codes: A61B 5/08 Detecting, measuring or recording devices for evaluating the respiratory organs A61B5/0205 takes precedence
• CPC Class Codes: A61B 5/1135 by monitoring thoracic expansion
• CPC Class Codes: A61B 5/18 for vehicle drivers or machine operators
• CPC Class Codes: A61B 5/6887 mounted on external non-worn devices, e.g. non-medical devices
• CPC Class Codes: G08B 21/06 indicating a condition of sleep, e.g. anti-dozing alarms

Abstract

A drowsiness detecting apparatus has a pulse wave sensor and a determination circuit. The sensor is provided to a steering wheel to detect a pulse wave of a vehicle driver gripping the steering wheel. The determination circuit generates a thorax pressure signal indicative of the depth of breathing by envelope-detecting a pulse wave signal of the sensor and determines whether the driver is drowsy by comparing a pattern of the thorax pressure signal with a reference pattern. The display and the buzzer notify the driver and any other passengers in the vehicle of the drowsiness of the driver by a visual indication and buzzing sound, respectively. A body surface motion may be used as a signal that indicates the depth of breathing.

Claims

1. A drowsiness detecting apparatus comprising:

breath depth detecting means for detecting a depth of breathing of a person;

determining means for determining drowsiness of the person, when the depth of breathing falls in a predetermined breathing condition including at least one of a sudden decrease in the depth of breathing and a periodic repetition of deep breathing and shallow breathing.

2. The drowsiness detecting apparatus as in claim 1, wherein the periodic repetition is set to 3 to 7 breaths.

3. The drowsiness detecting apparatus as in claim 1, wherein the breath depth detecting means includes:

a pulse wave sensor provided to a vehicle steering wheel for detecting a pulse wave of the person; and

a signal processor for detecting the depth of breathing based on a thorax pressure inside a thorax of the person by processing a pulse wave signal produced by the pulse wave sensor to detect the thorax pressure.

4. The drowsiness detecting apparatus as in claim 1, wherein the breath depth detecting means includes:

a body surface motion sensor provided to a vehicle seat for detecting a motion of a body surface of the person; and

a signal processor for detecting the depth of breathing by processing a detection signal produced by the body surface motion sensor.

5. The drowsiness detecting apparatus as in claim 1, wherein the determining means samples the depth of breathing for a predetermined period to generate a breathing waveform and compares the breathing waveform with a predetermined reference pattern.

6. The drowsiness detecting apparatus as in claim 1, wherein the determining means samples the depth of breathing for a predetermined period to generate a breathing waveform, calculates a change in amplitude of the breathing waveform and compares the change in amplitude with a predetermined reference value.

7. The drowsiness detecting apparatus as in claim 1, wherein the breath depth detecting means is thorax pressure detecting means that detects a thorax pressure inside a thorax of the person as the breath depth.

8. The drowsiness detecting apparatus as in claim 7, wherein the periodic repetition is set to 3 to 7 breaths.

9. The drowsiness detecting apparatus as in claim 7, wherein the thorax pressure detecting means includes:

a pulse wave sensor provided to a vehicle steering wheel for detecting a pulse wave of the person; and

a signal processor for detecting the thorax pressure by processing a pulse wave signal of the pulse wave sensor to detect the thorax pressure.

10. The drowsiness detecting apparatus as in claim 7, wherein the determining means samples the thorax pressure for a predetermined period to generate a thorax pressure waveform and compares the thorax pressure waveform with a predetermined reference pattern.

11. The drowsiness detecting apparatus as in claim 7, wherein the determining means samples the thorax pressure for a predetermined period to generate a thorax pressure waveform, calculates a change in amplitude of the thorax pressure waveform and compares the change in amplitude with a predetermined reference value.

12. The drowsiness detecting apparatus as in claim 1 further comprising:

notifying means for notifying drowsiness of the person when the drowsiness is determined by the determining means.

17. The drowsiness detecting method as in claim 12, wherein the detecting includes sampling the depth of breathing for a predetermined period to generate a breathing waveform, and determining includes comparing the breathing waveform with a predetermined reference pattern.

18. The drowsiness detecting method as in claim 12, wherein the determining includes sampling the depth of breathing for a predetermined period to generate a breathing waveform, calculating a change in amplitude of the breathing waveform and comparing the change in amplitude with a predetermined reference value.

19. The drowsiness detecting method as in claim 18, wherein the breathing waveform is generated by detecting each local maxima and local minima of sampled depth of breathing.

20. The drowsiness detecting method as in claim 12 further comprising:

notifying drowsiness of the person when the drowsiness is determined.

13. A drowsiness detecting method comprising:

detecting a depth of breathing of a person; and

determining drowsiness of the person, when the depth of breathing falls in a predetermined breathing condition including at least one of a sudden decrease in the depth of breathing and a periodic repetition of deep breathing and shallow breathing.

14. The drowsiness detecting method as in claim 13, wherein the periodic repetition is set to 3 to 7 breaths.

15. The drowsiness detecting method as in claim 13, wherein the detecting includes:

detecting a pulse wave of the person by a pulse wave sensor; and

detecting the depth of breathing based on a thorax pressure inside a thorax of the person by processing a pulse wave signal produced by the pulse wave sensor to detect the thorax pressure.

16. The drowsiness detecting method as in claim 13, wherein the detecting includes:

detecting a motion of a body surface of the person by a body surface motion sensor provided to a vehicle seat; and

detecting the depth of breathing by processing a detection signal produced by the body surface motion sensor.