Body movement and respiration monitor
View Patent ↗A monitor which can detect respiration of a sleeping person without being affected by the attitude of the sleeping person or the indoor illumination light and can easily evaluate detected respiration quantitatively through image measurement. The monitor comprises means ( 1 ) for projecting a specified illumination pattern, means ( 5 ) for picking up the image of projected light continuously, means ( 7 ) for calculating inter-frame moving amount of the illumination pattern from the image of two frames acquired by the image pickup means at different times, means ( 8 ) for generating a moving amount waveform data comprising inter-frame moving amounts arranged in time series, and means ( 9 ) for detecting the movement of an object from the moving amount waveform data.
1. A monitor comprising:
lighting pattern projecting means for projecting a specified lighting pattern;
image pickup means, whose optical axis is different from that of the lighting pattern projecting means, for picking up light of a projected wavelength continuously;
moving amount calculating means for calculating an inter-frame moving amount of the lighting pattern from two frames of images acquired by the image pickup means at different times;
moving amount waveform generating means for generating moving amount waveform data comprising inter-frame moving amounts arranged in time series; and
waveform detecting means for detecting a movement of an object to be picked up from the moving amount waveform data;
wherein the lighting pattern projecting means projects the lighting pattern that has a plurality of lighting spots or slit rays; and
the moving amount calculating means calculates an inter-frame moving amount of each lighting spot in an axial direction connecting the lighting pattern projecting means and the image pickup means while providing a positive or negative sign in accordance with a moving direction, and calculates a sum of moving amounts of pixels corresponding to the plurality of lighting spots or slit rays.
2. The monitor as set forth in claim 1 , wherein the waveform detecting means detects a body movement and respiratory movement of a sleeping person, the monitor further comprising:
safety deciding means for deciding the safety of the sleeping person from the body movement and respiratory movement of the sleeping person; and
signal outputting means for, when the safety deciding means decides that the sleeping person is in a dangerous state, outputting a signal indicating it.
3. The monitor as set forth in claim 2 , wherein the moving amount calculating means calculates an inter-frame moving amount in a partial region of the lighting pattern in an axial direction connecting the lighting pattern projecting means and the image pickup means, and determines a region in an image where an inter-frame moving amount in the partial region appears much greater than a predetermined amount or where an inter-frame movement in the partial region appears frequently beyond a predetermined amount as a region where the sleeping person exists, and the safety deciding means decides that the sleeping person is in a dangerous state when the region where the sleeping person exists moves in a shorter time than a predetermined time and moves frequently beyond a predetermined amount.
4. The monitor as set forth in claim 2 , wherein the moving amount calculating means calculates an inter-frame moving amount in a partial region of the lighting pattern in an axial direction connecting the lighting pattern projecting means and the image pickup means, and determines a region in an image where an inter-frame moving amount in the partial region appears much greater than a predetermined amount or where an inter-frame movement in the partial region appears more frequently than a predetermined frequency as a region where the sleeping person exists, and the safety deciding means decides that the sleeping person is in a dangerous state when the region where the sleeping person exists is brought closer to one end of the bed than a predetermined distance.
5. The monitor as set forth in claim 2 , comprising informing means for, based on a signal output from signal outputting means, informing a third party that the sleeping person is in a dangerous state.
6. The monitor as set forth in claim 5 , wherein the informing means informs the third party that the sleeping person is in a dangerous state by voices, characters, symbols, intensity of light including interior illumination light, or vibrations through a telecommunications line.
7. The monitor as set forth in claim 2 , wherein the waveform detecting means detects a periodic pattern as a respiratory pattern, and detects a variation having a high peak as a body movement pattern from the moving amount waveform data.
8. The monitor as set forth in claim 7 , wherein the safety deciding means decides that the sleeping person is in a dangerous state when a period of the respiratory pattern falls into disarray in a short time, when the period of the respiratory pattern suddenly changes, when the respiratory pattern continuously disappears, or when the body movement pattern frequently appears in a short time.
9. The monitor as set forth in claim 7 , wherein from among respiratory patterns, the waveform detecting means detects a value having a positive or negative sign corresponding to a movement in a direction from the lighting pattern projecting means to the image pickup means on an image and a value having a positive or negative sign corresponding to a movement in a direction from the image pickup means to the lighting pattern projecting means on the image as an expiratory pattern and as an inspiratory pattern, respectively, or vice versa.
10. The monitor as set forth in claim 9 , wherein the safety deciding means decides whether respiration belongs to normal respiration, Cheyne-Stokes respiration, central hyperventilation, ataxic respiration, or Kussmaul respiration from expiratory patterns and inspiratory patterns and decides that the sleeping person is in a dangerous state when the respiration belongs to any one of Cheyne-Stokes respiration, central hyperventilation, ataxic respiration, and Kussmaul respiration.
11. The monitor as set forth in claim 1 , wherein the waveform detecting means detects a periodic pattern as a respiratory pattern, and detects a variation having a high peak as a body movement pattern form the moving amount waveform data.
12. The monitor as set forth in claim 11 , wherein the safety deciding means decides that the sleeping person is in a dangerous state when a period of the respiratory pattern falls into disarray in a short time, when the period of the respiratory pattern suddenly changes, when the respiratory pattern continuously disappears, or when the body movement pattern frequently appears in a short time.
13. The monitor as set forth in claim 11 , wherein from among respiratory patterns, the waveform detecting means detects a value having a positive or negative sign corresponding to a movement in a direction from the lighting pattern projecting means to the image pickup means on an image and a value having a positive or negative sign corresponding to a movement in a direction from the image pickup means to the lighting pattern projecting means on the image as an expiratory pattern and as an inspiratory pattern, respectively, or vice versa.
14. The monitor as set forth in claim 13 , wherein the waveform detecting means counts zero crosses where signs are reversed between an expiratory pattern and an inspiratory pattern and counts respirations.
15. The monitor as set forth in claim 14 , wherein the waveform detecting means calculates a respiration number per unit time or a respiration period from the counted respirations.
16. The monitor as set forth in claim 13 , wherein the waveform detecting means calculates a respiration number per unit time or a respiration period by conducting a frequency analysis of the moving-amount waveform data or the sampling data obtained by sampling respiratory patterns, by calculating the most prominent frequency from a resulting frequency spectrum, and by calculating the respiration number per unit time or the respiration period from this frequency.
17. The monitor as set forth in claim 1 , wherein the waveform detecting means calculates a respiration number per unit time or a respiration period by conducting a frequency analysis of the moving-amount waveform data or the sampling data obtained by sampling respiratory patterns, by calculating the most prominent frequency from a resulting frequency spectrum, and by calculating the respiration number per unit time or the respiration period from this frequency.
18. The monitor as set forth in claim 17 , wherein the waveform detecting means conducts a frequency analysis with discrete Fourier transform or discrete wavelet transform.
19. The monitor as set forth in claim 1 , wherein the lighting pattern projecting means is disposed directly above a part close to one end of an edge of bedding facing a head or a foot of a person sleeping on the bedding, and the image pickup means is disposed directly above a part close to an opposite end thereof.
20. The monitor as set forth claim 1 , comprising presence-in-bed detecting means for detecting the presence/absence of a sleeping person.
21. The monitor as set forth in claim 1 , comprising a pressure sensitive switch that can be placed under the sleeping person and can be used to detect the presence/absence of the sleeping person.
22. The monitor as set forth in claim 1 , wherein the moving amount calculating means calculates an inter-frame moving amount of a lighting pattern in an axial direction connecting the lighting pattern projecting means and the image pickup means.