Patent Application
20140276149
The present application is based on and claims priority from Japanese Patent Application No. 2013-054493, filed Mar. 18, 2013, and Japanese Patent Application No. 2013-54492, filed Mar. 18, 2013, the disclosures of which are incorporated herein by reference.
1. Technical Field
The present invention relates to a biological information detection apparatus and the like.
2. Related Art
A biological information detection apparatus which detects biological information, such as a pulse wave of a human, is hitherto known. JP-A-2011-139725 and JP-A-2009-201919 disclose a pulsimeter of the related art which is an example of the biological information detection apparatus. The pulsimeter is put on, for example, an arm, a wrist, a finger, or the like, and detects pulsation resulting from heartbeat of a human body to measure a pulse rate.
The pulsimeter disclosed in JP-A-2011-139725 and JP-A-2009-201919 is a photoelectric pulsimeter, and a detection unit (pulse wave sensor) of the pulsimeter has a light emitting unit which emits light toward a subject (a region to be detected), and a light receiving unit which receives light (light having biological information) from the subject. In this pulsimeter, change in blood flow is detected as change in the amount of received light, thereby detecting a pulse wave. JP-A-2011-139725 discloses a pulsimeter which is put on a wrist, and JP-A-2009-201919 discloses a pulsimeter which is put on a finger.
In JP-A-2011-139725 and JP-A-2009-201919, a light transmitting member which transmits light from the light emitting unit or light from the subject is provided, and the light transmitting member has a contact surface with the subject (the skin of the wrist or the finger). Then, if a convex portion is provided on the contact surface of the light transmitting member, a pressing force is easily applied when coming into contact with the skin of the subject.
However, as a side effect, there is the effect of change in pressing force caused by shaking of the instrument of the biological information detection apparatus by body motion, motion (for example, clasp and unclasp operation) of the hand of a user on which the biological information detection apparatus is put. When change in pressing force is large, this means that a body motion noise component which is superimposed on a detection signal of the biological information is large.
For example, when a load by a load mechanism is small, or the like, if it is not possible to give a sufficient initial pressing force by the convex portion to the subject, there is a problem in that it is not possible to obtain an appropriate detection signal of the biological information.
An aspect of the invention relates to a biological information detection apparatus including a detection unit which has a light receiving unit receiving light from a subject, a light transmitting member which is provided on a housing surface side in contact with the subject of the biological information detection apparatus, transmits light from the subject, and has a convex portion in contact with the subject to give a pressing force to the subject when measuring biological information of the subject, and a pressing force suppression unit which is disposed periphery of the convex portion above the housing surface and suppresses the pressing force given to the subject by the convex portion, in which, when a value obtained by subtracting the height of the pressing force suppression unit from the height of the convex portion in a direction orthogonal to the housing surface is Δh, Δh>0.
Another aspect of the invention is directed to a biological information detection apparatus including a detection unit which has a light receiving unit receiving light from a subject, a light transmitting member which is provided on a housing surface side in contact with the subject of the biological information detection apparatus, transmits light from the subject, and has a convex portion in contact with the subject to give a pressing force to the subject when measuring biological information of the subject, and a pressing force suppression unit which is disposed in periphery of the convex portion above the housing surface and suppresses the pressing force given to the subject by the convex portion, in which the pressing force suppression unit has a pressing force suppression surface which extends in a second direction orthogonal to a first direction as a circumferential direction of a region to be detected of the subject in plan view in a direction orthogonal to the housing surface.
Still another aspect of the invention relates to a biological information detection apparatus including a detection unit which has a light receiving unit receiving light from a subject, a light transmitting member which is provided on a housing surface side in contact with the subject of the biological information detection apparatus, transmits light from the subject, and has a convex portion in contact with the subject to give a pressing force to the subject when measuring biological information of the subject, and a pressing force suppression unit which is disposed in periphery of the convex portion above the housing surface and suppresses the pressing force given to the subject by the convex portion, in which, when a latitudinal direction of the pressing force suppression surface is a first direction, a longitudinal direction of the pressing force suppression surface is a second direction, a position away from the position of the convex portion at a first distance in the second direction is a first position, a position away from the position of the convex portion at a second distance longer than the first distance in the second direction is a second position, the height of the pressing force suppression surface in a direction orthogonal to the housing surface at the first position is HS1, and the height of the pressing force suppression surface in the direction orthogonal to the housing surface at the second position is HS2, HS1>HS2.
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
According to some aspects of the invention, it is possible to provide a biological information detection apparatus or the like which can give an appropriate initial pressing force while reducing adverse effects caused by change in pressing force or the like.
According to some aspects of the invention, it is possible to provide a biological information detection apparatus or the like which can suppress degradation in quality of a detection signal caused by change in pressing force or the like.
An embodiment of the invention relates to a biological information detection apparatus including a detection unit which has a light receiving unit receiving light from a subject, a light transmitting member which is provided on a housing surface side in contact with the subject of the biological information detection apparatus, transmits light from the subject, and has a convex portion in contact with the subject to give a pressing force when measuring biological information of the subject, and a pressing force suppression unit which is disposed in periphery of the convex portion above the housing surface and suppresses the pressing force given to the subject by the convex portion, in which, when a value obtained by subtracting the height of the pressing force suppression unit from the height of the convex portion in a direction orthogonal to the housing surface is Δh, Δh>0.
According to this embodiment, the convex portion of the light transmitting member comes into contact with the subject when measuring the biological information of the subject, and light passing through the light transmitting member is received by the light receiving unit of the detection unit, thereby detecting the biological information of the subject. In this embodiment, the pressing force suppression unit which suppresses the pressing force given to the subject by the convex portion is disposed in periphery of the convex portion, and, in regard to Δh which is the value obtained by subtracting the height of the pressing force suppression unit from the height of the convex portion, the relationship of Δh>0 is established. In this way, the convex portion protrudes such that Δh>0, making it possible to give an appropriate initial pressing force to the subject by the convex portion with a small load. The pressing force given by the convex portion is suppressed by the pressing force suppression unit, making it possible to reduce change in pressing force or the like. Therefore, it is possible to provide a biological information detection apparatus which can given an appropriate initial pressing force to the subject while reducing adverse effects caused by change in pressing force or the like.
In this embodiment, when the amount of change in pressing force of the convex portion with respect to a load by a load mechanism generating the pressing force of the convex portion is defined as the amount of change in pressing force, the pressing force suppression unit may suppress the pressing force given to the subject by the convex portion such that the amount of change in pressing force in a second load range in which the load of the load mechanism is greater than FL1 becomes smaller than the amount of change in pressing force in a first load range in which the load of the load mechanism is 0 to FL1.
In this way, if the pressing force of the convex portion is suppressed such that the amount of change in pressing force in the second load range becomes smaller than the amount of change in pressing force in the first load range, it becomes possible to suppress the pressing force given to the subject by the convex portion to reduce change in pressing force or the like while giving an appropriate initial pressing force to the subject by the convex portion.
In this embodiment, the pressing force suppression unit may have a pressing force suppression surface which expands outward from around the convex portion.
With this configuration, it becomes possible to suppress the pressing force given to the subject by the convex portion equally and efficiently using the pressing force suppression surface which expands outward from around the convex portion.
In this embodiment, when a position away from the position of the convex portion at a first distance in a predetermined direction is a first position, a position away from the position of the convex portion at a second distance longer than the first distance in the predetermined direction is a second position, the height of the pressing force suppression surface in a direction orthogonal to the housing surface at the first position is HS1, and the height of the pressing force suppression surface in the direction orthogonal to the housing surface at the second position is HS2, HS1>HS2.
If the relationship of HS1>HS2 is established, it is possible to effectively suppress the occurrence of change in pressing force of the convex portion or the like due to change in the contact state with the subject or the like at a location away from the convex portion.
In this embodiment, the pressing force suppression surface may be inclined such that the height in the direction orthogonal to the housing surface decreases toward a predetermined direction from the position of the convex portion.
If the inclination is provided, since the height of the pressing force suppression surface in the direction orthogonal to the housing surface decreases toward the side away from the convex portion, it is possible to reduce adverse effects due to change in the contact state with the subject or the like at a location away from the convex portion.
In this embodiment, the light transmitting member may have the convex portion at least a part of which protrudes toward the subject, and a body potion which is provided on the lower side of the convex portion opposite to the subject, the body portion may be formed to extend from the position of the convex portion to the lower side of a cover member of the housing surface, and the pressing force suppression surface may be the surface of the cover member.
With this configuration, it becomes possible to form the pressing force suppression surface effectively using the cover member above the body portion.
In this embodiment, when a direction orthogonal to a first direction is a second direction, and a direction opposite to the second direction is a third direction, the pressing force suppression surface may be a continuous surface in at least the first direction, the second direction, and the third direction around the convex portion.
With this configuration, since it becomes possible to suppress the pressing force of the convex portion by the pressing force suppression surface around the convex portion in at least the first, second, and third directions, it becomes possible to suppress the pressing force equally and efficiency.
In this embodiment, the convex portion may protrude from the pressing force suppression surface toward the subject such that Δh>0.
If the convex portion protrudes from the pressing force suppression surface such that Δh>0, after the convex portion comes into contact with the subject to give the initial pressing force, the pressing force suppression surface comes into contact with the subject, thereby suppressing the pressing force given to the subject by the convex portion.
In this embodiment, the biological information detection apparatus may further include a diaphragm unit which is provided between the light transmitting member and the detection unit, between the light transmitting member and the subject, or inside the light transmitting member, and narrows light from the subject in an optical path between the subject and the detection unit.
If the diaphragm unit is provided, even when stray light occurs due to change in the contact state of the contact surface with the subject or the like, it is possible to suppress the entrance of stray light to the light receiving unit and to detect appropriate biological information.
In this embodiment, the detection unit may include a light emitting unit which emits light to the subject, the light transmitting member may transmit light from the light emitting unit, and the biological information detection apparatus may further include a light shielding unit which is provided between the light receiving unit and the light emitting unit.
If the light shielding unit is provided, it is possible to suppress the entrance of direct light from the light emitting unit to the light receiving unit and to detect appropriate biological information.
In this embodiment, 0.01 mm≦Δh≦0.5 mm. Also, in this embodiment, 0.05 mm≦Δh≦0.35 mm.
In this way, Δh is set to a small value, and thus an increase in noise component due to change in pressing force or the like is suppressed while giving the minimum pressing force necessary for detecting the biological information to the subject, making it possible to improve quality of a detection signal of the biological information.
In this embodiment, the convex portion may have a curved shape in at least a portion in contact with the subject.
With this configuration, it becomes possible to give a pressing force to the subject by the convex portion in a stable contact state.
In this embodiment, when the radius of curvature of the curved shape of the convex portion is R, R≧8 mm.
With this configuration, it becomes possible to give a pressing force efficiently under a condition of a radius of curvature at which the contact state with the surface of the subject is stable.
In this embodiment, the light transmitting member having the convex portion may be fixed to the housing surface.
With this configuration, for example, even when a load is applied by a load mechanism or the like, it becomes possible to prevent the light transmitting member from relatively moving with respect to the housing surface.
In this embodiment, the pressing force suppression unit may be formed of an insulating member.
With this configuration, the pressing force suppression unit is formed by the insulating member formed of an insulating material, instead of a conductive member, thereby suppressing the pressing force of the convex portion.
In this embodiment, a pulse wave may be detected as the biological information.
However, the biological information to be detected by the biological information detection apparatus is not limited to the pulse wave.
Another embodiment of the invention relates to a biological information detection apparatus including a detection unit which has a light receiving unit receiving light from a subject, a light transmitting member which is provided on a housing surface side in contact with the subject of the biological information detection apparatus, transmits light from the subject, and has a convex portion in contact with the subject to give a pressing force when measuring biological information of the subject, and a pressing force suppression unit which is disposed in periphery of the convex portion above the housing surface and suppresses the pressing force given to the subject by the convex portion, in which the pressing force suppression unit has a pressing force suppression surface which extends in a second direction orthogonal to a first direction as a circumferential direction of a region to be detected of the subject in plan view in a direction orthogonal to the housing surface.
According to this embodiment, the convex portion of the light transmitting member comes into contact with the subject when measuring the biological information of the subject, light passing through the light transmitting member is received by the light receiving unit of the detection unit, thereby detecting the biological information of the subject. The pressing force suppression unit which suppresses the pressing force to the subject by the convex portion is disposed in periphery of the convex portion. When the circumferential direction of the region to be detected of the subject is the first direction, and the direction orthogonal to the first direction is the second direction, in this embodiment, the pressing force suppression unit has the pressing force suppression surface which extends in the second direction. In this way, if the pressing force suppression surface which extends in the second direction is provided, even when there is motion or the like in the subject, it becomes possible to reduce change in pressing force or the like in the convex portion due to the motion or the like. Therefore, it becomes possible to effectively suppress degradation in quality of a detection signal by change in pressing force or the like.
In this embodiment, when the housing surface is divided into a first region and a second region by a center line in the first direction, the convex portion may be provided in the first region, the second direction may be a direction orthogonal to the first direction and from the convex portion toward the center line, and the pressing force suppression surface may be a surface which extends in the second direction from the position of the convex portion.
In this way, if the convex portion is arranged at a position deviated from the center portion, and the pressing force suppression surface which extends in the second direction from the position of the convex portion, even when there is motion or the like in the subject, it becomes possible to reduce change in pressing force or the like in the convex portion due to the motion or the like.
In this embodiment, when a direction opposite to the second direction is a third direction, the distance between the position of the convex portion and a first end portion in the second direction of the pressing force suppression surface is LE1, and the distance between the position of the convex portion and a second end portion in the third direction of the pressing force suppression surface is LE2, LE1>LE2.
With this configuration, since the convex portion is arranged at a position near the second end portion (the end portion at the distance LE2) of the pressing force suppression surface, and the distance LE1 between the position of the convex portion and the first end portion of the pressing force suppression surface becomes longer, it becomes possible to form the pressing force suppression surface which extends in the second direction from the position of the convex portion.
In this embodiment, when the width of the pressing force suppression surface in the first direction at the position of the convex portion is WS, WS<LE1.
With this configuration, the width WS of the pressing force suppression surface in the first direction decreases, thereby forming the pressing force suppression surface in which the first direction becomes the latitudinal direction and the second direction becomes the longitudinal direction.
In this embodiment, the pressing force suppression surface may be a surface which extends in the second direction from the position of the convex portion beyond a center line in the first direction of the housing surface.
In this way, if the pressing force suppression surface is the surface which extends in the second direction beyond the center line, since it is possible to increase the area of the contact surface with the subject, it becomes possible to effectively suppress change in pressing force or the like in the convex portion.
In this embodiment, when the length of the pressing force suppression surface in the second direction at the position of the convex portion is LS, and the length of the housing surface in the second direction at the position of the convex portion is LC, LS<LC.
With this configuration, it is possible to effectively suppress a situation in which the length LS of the pressing force suppression surface in the second direction becomes too long, and change in pressing force or the like occurs and causes degradation in signal quality of a detection signal.
In this embodiment, when the biological information detection apparatus is put on a wrist of the subject, the convex portion may be provided on a hand side out of a hand and a lower arm of the subject, and the second direction may be a direction from the hand of the subject to the lower arm.
With this configuration, since the convex portion is provided in the first region on the hand side, and the pressing force suppression surface becomes the surface which extends from the convex portion provided on the hand side toward the lower arm, it becomes possible to realize improvement of comfort of the biological information detection apparatus put on the wrist, suppression of change in pressing force, or the like.
In this embodiment, when a position away from the position of the convex portion at a first distance in the second direction is a first position, a position away from the position of the convex portion at a second distance longer than the first distance in the second direction is a second position, the width of the pressing force suppression surface in the first direction at the first position is WS1, and the width of the pressing force suppression surface in the first direction at the second position is WS2, WS1>WS2.
If the relationship of WS1>WS2 is established, since the contact area with the subject decreases toward the side away from the convex portion, it is possible to suppress adverse effects by change in the contact state with the subject at a location away from the convex portion.
In this embodiment, the pressing force suppression surface may decrease in width in the first direction toward the second direction beyond a center line in the first direction of the housing surface.
With this configuration, since the width of the pressing force suppression surface decreases toward the side away from the convex portion, and the contact area with the subject decreases, it is possible to suppress adverse effects by change in the contact state with the subject or the like at a location away from the convex portion.
In this embodiment, when the length of the pressing force suppression surface in the second direction at the position of the convex portion is LS, 15 mm<LS<25 mm.
In this way, if the length Ls of the pressing force suppression surface is set, it is possible to effectively suppress a situation in which LS becomes too short to cause a decrease in the contact area, the pressing force suppression effect is deteriorated, or LS becomes too longer to cause the occurrence of change in pressing force or the like, and signal quality of a detection signal is degraded.
Still another embodiment of the invention relates to a biological information detection apparatus including a detection unit which has a light receiving unit receiving light from a subject, a light transmitting member which is provided on a housing surface side in contact with the subject of the biological information detection apparatus, transmits light from the subject, and has a convex portion in contact with the subject to give a pressing force when measuring biological information of the subject, and a pressing force suppression unit which is disposed in periphery of the convex portion above the housing surface and suppresses the pressing force given to the subject by the convex portion, in which, when a latitudinal direction of the pressing force suppression surface is a first direction, a longitudinal direction of the pressing force suppression surface is a second direction, a position away from the position of the convex portion at a first distance in the second direction is a first position, a position away from the position of the convex portion at a second distance longer than the first distance in the second direction is a second position, the height of the pressing force suppression surface in a direction orthogonal to the housing surface at the first position is HS1, and the height of the pressing force suppression surface in the direction orthogonal to the housing surface at the second position is HS2, HS1>HS2.
If the relationship of HS1>HS2 is established, it is possible to effectively suppress change in pressing force of the convex portion or the like due to change in the contact state with the subject or the like at a location away from the convex portion.
Hereinafter, this embodiment will be described. This embodiment described below is not unduly limited to the disclosure of the invention described in the appended claims. All configurations described in this embodiment are not necessarily the essential components of the invention.
As shown in
An indicator 343 is provided in the fixing member 342, and a scale for indicating an appropriate slide range is attached to the indicator 343. Specifically, points P1 and P2 which indicate an appropriate slide range (pressing force range) are attached to the indicator 343. If the end portion on the band 320 side of the slide member 344 is located within the range of the points P1 and P2, it is ensured that the slide member is within an appropriate slide range (pressing force range), and an appropriate tensile force is applied. A user inserts the rod of the connection 340 corresponding to a buckle into the band hole of the band 322 so as to be within the appropriate slide range, and puts the biological information detection apparatus on his/her wrist. With this, it is ensured to some extent that the pressing force of the pulse wave sensor (a convex portion of a light transmitting member) to the subject becomes an assumed appropriate pressing force. The details of the structure of the biological information detection apparatus shown in
In
The light transmitting member 30 is provided on the housing surface 22 side in contact with the subject of the biological information detection apparatus, and transmits light from the subject. The light transmitting member 30 comes into contact with the subject when measuring the biological information of the subject. For example, a convex portion 40 of the light transmitting member 30 comes into contact with the subject. While it is preferable that the surface shape of the convex portion 40 is a curved shape (spherical shape), the invention is not limited thereto, and various shapes may be used. The light transmitting member 30 may be transparent to the wavelength of light from the subject, and a transparent material may be used, or a colored material may be used.
As shown in
As shown in
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As shown in
The convex portion 40 comes into contact with the subject when measuring the biological information of the subject and gives a pressing force. Specifically, when the user puts the biological information detection apparatus on his/her wrist to detect biological information, such as a pulse wave, the convex portion 40 comes into contact with the skin of the wrist of the user to give the pressing force. The pressing force is generated by a load of the load mechanism described in
On the housing surface 22 of the biological information detection apparatus, a pressing force suppression unit 60 which suppresses the processing force to be given to the subject (the skin of the wrist) by the convex portion 40 is provided. In
In
As shown in
The detection unit 130 has a light receiving unit 140 and a light emitting unit 150. The light receiving unit 140 and the light emitting unit 150 are mounted on a substrate 160. The light receiving unit 140 receives light (reflected light, transmitted light, or the like) from the subject. The light emitting unit 150 emits light to the subject. For example, if the light emitting unit 150 emits light to the subject, and light is reflected by the subject (blood vessel), the light receiving unit 140 receives and detects reflected light. The light receiving unit 140 can be realized by, for example, a light receiving element, such as a photodiode. The light emitting unit 150 can be realized by a light emitting element, such as an LED. For example, the light receiving unit 140 can be realized by a PN junction diode element formed on a semiconductor substrate. In this case, an angle limiting filter for narrowing a light receiving angle or a wavelength limiting filter for limiting the wavelength of light entering the light receiving element may be formed on the diode element.
In the case of a pulsimeter as an example, light from the light emitting unit 150 travels inside the subject, and is diffused or scattered by an epidermis, a corium, a subcutaneous tissue, and the like. Thereafter, the light reaches the blood vessel (a region to be detected) and is reflected. At this time, a part of light is absorbed by the blood vessel. Since the absorption rate of light in the blood vessel changes due to the effect of a pulse, and the amount of reflected light also changes, the light receiving unit 140 receives the reflected light to detect change in the amount of light, thereby detecting a pulse rate or the like as biological information.
In
In this embodiment, as shown in
In
As shown in
In this embodiment, for example, when the height of the convex portion 40 in the direction DRH orthogonal to the housing surface of the biological information detection apparatus is referred to as HA (for example, the height of the vertex of the curved shape of the convex portion 40), the height of the pressing force suppression unit 60 is referred to as HB (for example, the height at the highest location), and the value (the difference between the heights HA and HB) obtained by subtracting the height HB from the height HA is referred to as Ah, the relationship of Δh=HA−HB>0 is established. For example, the convex portion 40 protrudes from the pressing force suppression surface of the pressing force suppression unit 60 toward the subject such that Δh>0. That is, the convex portion 40 protrudes toward the subject by the amount corresponding to Ah from the pressing force suppression surface of the pressing force suppression unit 60.
In this way, the convex portion 40 having the relationship of Δh>0 is provided, making it possible to give an initial pressing force for exceeding, for example, a vein vanishing point to the subject. The pressing force suppression unit 60 for suppressing the pressing force given to the subject by the convex portion 40 is provided, making it possible to minimize change in pressing force in the use range in which the biological information is measured by the biological information detection apparatus, and to achieve reduction in noise component or the like. If the convex portion 40 protrudes from the pressing force suppression surface such that Δh>0, after the convex portion 40 comes into contact with the subject to give the initial pressing force, the pressing force suppression surface of the pressing force suppression unit 60 comes into contact with the subject, thereby suppressing the pressing force given to the subject by the convex portion 40. The vein vanishing point is a point which, when the convex portion 40 is brought into contact with the subject and the pressing force gradually increases, a signal due to a vein superimposed on a pulse wave signal is vanished or becomes small without affecting pulse wave measurement.
For example, in
In this case, the pressing force suppression unit 60 suppresses the pressing force given to the subject by the convex portion 40 such that the amount VF2 of change in pressing force in a second load range RF2 in which the load of the load mechanism is greater than FL1 becomes smaller than the amount VF1 of change in pressing force in a first load range RF1 in which the load of the load mechanism becomes 0 to FL1. That is, in the first load range RF1 as an initial pressing force range, the amount VF1 of change in pressing force increases, and in the second load range RF2 as the use range of the biological information detection apparatus, the amount VF2 of change in pressing force decreases.
That is, in the first load range RF1, the amount VF1 of change in pressing force increases, thereby increasing the slope of the characteristic of change in pressing force with respect to the load. The pressing force having a large slope of the change characteristic is realized by Δh corresponding to the amount of protrusion of the convex portion 40. That is, the convex portion 40 having the relationship of Δh>0 is provided, whereby, even when the load by the load mechanism is small, it becomes possible to give the initial pressing force necessary for exceeding the vein vanishing point to the subject.
In the second load range RF2, since the amount VF2 of change in pressing force is small, it is possible to decrease the slope of the characteristic of change in pressing force with respect to the load. The pressing force having a small slope of the change characteristic is realized by pressing force suppression by the pressing force suppression unit 60. That is, the pressing force given to the subject by the convex portion 40 is suppressed by the pressing force suppression unit 60, whereby, in the use range of the biological information detection apparatus, even when there is change in load or the like, it becomes possible to minimize change in pressing force. Therefore, reduction in the noise component or the like is achieved.
In this way, an optimum pressing force (for example, about 16 kPa) is given to the subject, making it possible to obtain a pulse wave detection signal having a higher M/N ratio (S/N ratio). That is, it is possible to increase a signal component of the pulse wave sensor and to reduce a noise component. Here, M represents a signal level of the pulse wave detection signal, and N represents a noise level.
The range of the pressing force for pulse wave measurement is set to a range corresponding to the second load range RF2, making it possible to minimize change in pressing force (for example, about ±4 kPa) and to reduce the noise component.
The pressing force suppression unit 60 has the pressing force suppression surface which expands outward from around the convex portion 40. Specifically, as shown in
In
In
In
In
As the distance between the light receiving unit 140 and the light emitting unit 150 decrease, optical efficiency or performance is improved. However, if the distance between the light receiving unit 140 and the light emitting unit 150 decreases, there is an increasing possibility that direct light from the light emitting unit 150 enters the light receiving unit 140 and performance is deteriorated. Accordingly, in
For example, in
As in
In
In this way, in this embodiment, the convex portion 40 having the relationship of Δh>0 is provided, whereby, in the initial pressing force range, the pressing force given to the subject by the convex portion 40 increases quickly. In the other hand, the pressing force suppression unit 60 (pressing force suppression surface) is provided around the convex portion 40, whereby, in the use range, with pressing force suppression by the pressing force suppression unit 60, the amount of change in pressing force which is the amount of change in pressing force with respect to the load decreases to reduce change in pressing force.
Δh which represents the amount of protrusion of the convex portion 40 is an important parameter which specifies an optimum pressing force. That is, in order to constantly give the pressing force for exceeding the vein vanishing point, a certain amount of protrusion is required, and Δh should be set to a large value. However, if Δh becomes an excessive value, this may cause a decrease in the signal component of the pulse wave sensor or an increase in change in pressing force.
Accordingly, the minimum Δh is selected in a range in which the signal component of the pulse wave sensor can be sufficiently ensured, that is, in a range in which the optimum pressing force can be given. That is, in the range in which the optimum pressing force can be given, the smaller Δh, the lower the noise component can be suppressed.
For example,
For example, in
As Δh decreases from 0.5 mm to 0.35 mm, the MN ratio tends to increase. As Δh decreases from 0.35 mm to 0.25 mm, the MN ratio tends to increase. The rate of increase of the MN ratio in the range of 0.35 mm to 0.25 mm tends to be higher than the rate of increase in the range of 0.5 mm to 0.35 mm.
From above, the range of Δh is preferably 0.01 mm≦Δh≦0.5 mm, and more preferably, 0.05 mm≦Δh≦0.35 mm. For example, when Δh=about 0.25 mm, it becomes possible to maximize the MN ratio. That is, in this way, Δh is set to a small value, whereby an increase in the noise component due to change in pressing force or the like is suppressed while gives the minimum pressing force for exceeding the vein vanishing point to the subject, making it possible to increase the MN ratio representing signal quality.
In this regard, if the convex portion 40 is provided in the light transmitting member 30, and Δh>0, even if the load by the load mechanism is not so large, it becomes possible to efficiently give the optimum pressing force (initial pressing force) within the range between the vein vanishing point and the artery vanishing point to the subject. Accordingly, it is possible to obtain a pulse wave detection signal having a high MN ratio as shown in
In this embodiment, the convex portion 40 has a curved shape in at least a portion in contact with the subject. In this way, if the surface shape of the convex portion 40 is a curved shape, it becomes possible to give the pressing force to the subject by the convex portion in a stable contact state.
In this case, if the radius of curvature of the curved shape of the convex portion is R, for example, it is preferable that R≧8 mm. With this, it becomes possible to efficiently give the pressing force under a condition of a radius of curvature at which the contact state with the surface of a living body, such as hide, is stable.
For example,
Until the radius R of curvature becomes 8 mm (R8), as the radius of curvature increases, the pulse DC value (Δ pulse DC value) increases. If the radius R of curvature becomes equal to or greater than 8 mm, the increase in the pulse DC value is saturated. In other words, the radius R of curvature is equal to or greater than 8 mm, whereby the pulse DC value is made stable. In this way, the minimum R such that an appropriate pressing force (the pressing force for exceeding the vein vanishing point) can be given under a condition in which the contact state with hide is stable becomes, for example, 8 mm. Accordingly, it is preferable that, in regard to the radius R of curvature, the relationship of R≧8 mm is established. The diaphragm units 82 and 84 or the light shielding unit 100 described below in detail is provided, making it possible to make the pulse DC value more stable.
Next, a detailed example of the pressing force suppression unit 60 will be described. In the pressing force suppression unit 60 (bank structure), the area (the contact area with the subject) of the pressing force suppression surface 62 increases, thereby suppressing change in pressing force (contact pressure) applied near the convex portion 40.
However, if the area of the pressing force suppression surface 62 is too large, or the height of the pressing force suppression surface 62 with respect to the pulse wave sensor is too high, there is a problem in that the pressing force applied near the convex portion 40 may not reach an appropriate range, and quality of the pulse wave detection signal may not be sufficient.
If the area of the pressing force suppression surface 62 is small or the height of the pressing force suppression surface 62 is low, there is a problem in that the pressing force suppression effect may not be sufficiently exhibited. When the pressing force suppression effect may not be exhibited, this means that change in pressing force increases and the noise component of the pulse wave detection signal increases.
For example, as shown in
In order to solve the problem as described above, as shown in
As shown in
For example, a direction which is orthogonal to the first direction DR1 and from the convex portion 40 toward the center line CL is referred to as the second direction DR2. When the biological information detection apparatus is put on the wrist of the subject, the second direction DR2 becomes the direction from the hand of the subject toward the lower arm. At this time, the convex portion 40 is provided on the hand side out of the hand and the lower arm of the subject. That is, the convex portion 40 is provided in the first region RG1 on the hand side out of the first region RG1 on the hand side and the second region RG2 on the lower arm side.
In this embodiment, as shown in
Specifically, the pressing force suppression surface 62 is the surface which extends in the second direction DR2 from the position PS of the convex portion 40 beyond the center line CL. For example, as shown in
The lengths LS and LC are the length of the pressing force suppression surface 62 (pressing force suppression unit) in the second direction DR2 at the position PS of the convex portion 40. Specifically, when a line which is orthogonal to the center line CL and passes through the position PS of the convex portion 40 is referred to as ML, LS is the length of the pressing force suppression surface 62 on the line ML, and LC is the length of the housing surface 22 (rear lid) on the line ML.
It is assumed that a direction opposite to the second direction DR2 is the third direction DR3, the distance between the position PS of the convex portion 40 and the first end portion ES1 toward the second direction DR2 of the pressing force suppression surface 62 (pressing force suppression unit) is LE1, and the distance between the position PS of the convex portion 40 and a second end portion ES2 toward the third direction DR3 of the pressing force suppression surface 62 is LE2. In this case, in
With this configuration, since LE2 is small, the convex portion 40 is arranged near the second end portion ES2 of the pressing force suppression surface 62. Since LE1 is large, it becomes possible to form the pressing force suppression surface 62 which expands over a long distance from the position of the convex portion 40 toward the first end portion ES1.
When the width of the pressing force suppression surface 62 in the first direction DR1 at the position PS of the convex portion 40 is WS, WS<LE1.
With this configuration, the width WS of the pressing force suppression surface 62 in the first direction DR1 decreases, thereby forming the pressing force suppression surface 62 in which the first direction DR1 becomes the latitudinal direction and the second direction DR2 becomes the longitudinal direction.
The first and second end portions ES1 and ES2 are, for example, the end portions of the pressing force suppression surface 62 (pressing force suppression unit) on the line ML orthogonal to the center line CL. LE1 is the distance between the position PS of the convex portion 40 and the first end portion ES1 on the line ML, and LE2 is the distance between the position PS of the convex portion 40 and the second end portion ES2 on the line ML. WS is the width of the pressing force suppression surface 62 (pressing force suppression unit) on a line which passes through the position PS of the convex portion 40 and is parallel to the center line CL.
For example, the arm of a human has a tapered shape which increases in thickness from the hand side toward the elbow side, and the elbow side has greater change in diameter of the arm than the hand side.
In this regard, in this embodiment, as shown in
As described referring to
In this case, if the contact area of the pressing force suppression surface 62 expands toward the first direction DR1 of
Accordingly, in
With this configuration, the width WS decreases to suppress interference between the pressing force suppression surface 62 and the radius or ulna, it becomes possible to sufficiently ensure the initial pressing force by the convex portion 40 (D1 of
In this case, if the length of the pressing force suppression surface 62 in the second direction DR2 is too long so as to ensure the contact area, motion of a muscle, a tendon, or the like, change in diameter of the arm, or the like at a position (for example, the first end portion ES1 on the lower arm side) away from the convex portion 40 is transmitted to the portion of the convex portion 40 (pulse wave sensor). Accordingly, change in pressing force in the convex portion 40 occurs, and as a result, body motion noise is more greatly superimposed.
Accordingly, in
In this embodiment, as shown in
For example, in
The inclination is provided, whereby, for example, it is possible to suppress pressing force concentration near the first end portion ES1 on the second direction DR2 side (nine o'clock side) of the pressing force suppression surface 62. Accordingly, the load is easily applied to the convex portion 40, and it becomes easy to obtain an appropriate pressing force. For example, as described above, the arm has a tapered shape. Accordingly, for example, if the first end portion ES1 on the second direction DR2 side is high, even if the bands 320 and 322 of
As shown in
For example, when the pressing force suppression surface 62 has a perfect circular shape, the contact surface may come into contact with the radius or the ulna to make it difficult to sufficiently apply the initial pressing force, or the area of the contact surface decreases to make it not possible to sufficiently suppress the pressing force of the convex portion 40 in the use range.
In this regard, as in this embodiment, the contact surface expands toward the second direction DR2 (nine o'clock side), whereby change in load in the convex portion 40 decreases and change in pressing force decreases. As a result, the MN ratio (the magnitude of a power spectrum of a pulse component/the magnitude of a power spectrum of a noise component) which represents quality of the pulse wave detection signal increases.
If LS is too long to be LS≧25 mm, motion of a muscle, a tendon, or the like, change in diameter of the arm, or the like near the first end portion ES1 of the pressing force suppression surface 62 is transmitted to the convex portion 40 and body motion noise is greatly superimposed, causing a decrease in the MN ratio.
In this regard, in this embodiment, the length LS of the pressing force suppression surface 62 in the second direction DR2 at the position of the convex portion 40 is, for example, 15 mm<LS<25 mm. Specifically, LS is about 20 mm. With this configuration, since LS is long, it is possible to sufficiently ensure the contact area, and since LS is not too long and motion in the first end portion ES 1 is less transmitted as much, it becomes possible to realize a high MN ratio.
As shown in
Next, modifications of this embodiment will be described.
In
In this case, in the first modification of
The pressing force suppression surface 62 having a shape shown in
In the second modification, while the convex portion 40 is provided in the light transmitting member 30, the convex portion 40 is provided at a position deviated from the center position of the light transmitting member 30. While the pressing force suppression unit 60 is provided through a groove portion 42 around the convex portion 40, the shape or structure of the pressing force suppression unit 60 (pressing force suppression surface) is different from that in
In the second modification, as shown in
In this way, in regard to the shape or structure of the pressing force suppression unit 60, various modifications may be made. For example, when the biological information detection apparatus is put on a region other than the wrist, it is not necessary that, as in
For example, when the inclination or the like as shown in
In
Next, various examples of the shape or structure of the light transmitting member 30 will be described.
As shown in
The body portion 50 is provided on the lower side (in the drawing, the upper side) of the convex portion 40 which is the side (detection unit side) opposite to the subject. The body portion 50 is the main body of the light transmitting member 30, and the convex portion 40 for coming into contact with the subject is formed as the body portion 50 as a main body.
In the light transmitting member 30 (body portion 50), a surface on the side on which the convex portion 40 is formed is referred to as a first surface, and a surface on the rear side of the first surface is referred to as a second surface. Then, in
In
For example, if a relatively soft subject, such as skin, comes into contact with the contact surface of the light transmitting member 30 formed of a hard material, such as resin or glass, a region which does not come into contact with skin or a region where a contact pressure is weak occurs near the marginal portion (peripheral portion) of the light transmitting member 30. Accordingly, for example, if a flat portion is provided around the convex portion 40 with no groove portion 42 as shown in
In this regard, if the groove portion 42 as shown in
As indicated by E1 of
That is, as in
With this structure, it becomes possible to improve waterproof performance, and to prevent a situation in which, for example, a liquid, such as water, intrudes inside the biological information detection apparatus and causes failure of the detection unit 130 or the like. That is, for example, if a structure is made, in which the body portion 50 is cut at a portion indicated by E2 of
In this regard, at E1 of
In
In regard to the shape or structure of the light transmitting member 30, various modifications may be made. For example, in the light transmitting member 30 of
In
In the biological information detection apparatus of this embodiment, in the light transmitting member 30, a surface which comes into contact with skin as the subject becomes a contact surface having a finite area. In this embodiment, for example, a relatively soft subject, such as skin, comes into contact with the contact surface having a finite area of the light transmitting member 30 formed of a hard material, such as resin or glass. Then, from the viewpoint of theory of elasticity, a region which does not come into contact with skin or a region where a contact pressure is weak occurs near the marginal portion (peripheral portion) of the light transmitting member 30. Even when an external force is applied to the instrument of the biological information detection apparatus, and momentum is generated in the instrument, and a region near the marginal portion of the contact surface is most likely to be steady.
In light passing among the light emitting unit 150, skin, the light receiving unit 140 through this region, light intensity is likely to be optically generated due to change in dynamic contact state. If light enters the light receiving unit 140, light becomes noise having no correlation with a pulse component.
Even in a static contact state, signal quality may be degraded. If there is no proper contact with skin, external light which does not arise from the light emitting unit 150 enters the light receiving unit 140. When the contact pressure is excessive, a subcutaneous blood vessel is crushed, whereby a pulsation component is less brought into light which passes through this region.
As such noise is greatly superimposed, signal quality of the pulse wave detection signal is degraded, and in various kinds of biological measurements, such as pulse measurement, reliability of measured data is degraded.
For example,
For example,
For example, in
However, as will be apparent from
In this case, if optimization is made with the contact pressure of the center portion, the contact pressure of the marginal portion is less than an optimum range. If optimization is made with the contact pressure of the marginal portion, the contact pressure of the center portion is excessive with respect to the optimum range.
When the contact pressure is less than the optimum range, in a case where the pulse wave sensor comes into contact with skin or is detached from skin due to shaking of the apparatus, or even if the pulse wave sensor is in contact with skin, the pulse wave sensor does not crushes the vein, whereby body motion noise is superimposed on the pulse wave detection signal. If the noise component is reduced, it becomes possible to obtain a pulse wave detection signal having a higher M/N ratio (S/N ratio).
In order to solve the above-described problem, as shown in
In this way, in this embodiment, the diaphragm units 80 and 82 are provided such that light (stray light) at the locations or the like indicated by A1 and A2 of
In
That is, as the distance between the light receiving unit 140 and the light emitting unit 150 decreases, optical efficiency or performance is improved. For example, optical efficiency or performance is deteriorated in inverse proportion to the square of the distance. Accordingly, it is preferable to decrease the distance between the light receiving unit 140 and the light emitting unit 150 as small as possible.
However, if the distance between the light receiving unit 140 and the light emitting unit 150 decreases, there is an increasing possibility that direct light from the light emitting unit 150 enters the light receiving unit 140 and performance is deteriorated.
Accordingly, the light shielding unit 100 is provided between the light receiving unit 140 and the light emitting unit 150 to inhibit direct light from the light emitting unit 150 from entering the light receiving unit 140. That is, in this embodiment, as described above, in order to eliminate optical adverse effects from a path in which the contact state of the subject and the contact surface becomes unstable, the diaphragm units 80 and 82 are provided. The adverse effects by direct light of the light emitting unit 150 are eliminated by the light shielding unit 100. With this configuration, it becomes possible to ensure optical stability of a photoelectric pulse wave sensor by the diaphragm units 80 and 82 which eliminate noise due to change in the contact state of the subject and the contact surface, and the light shielding unit 100 which eliminates direct light of the light emitting unit 150. The light shielding unit 100 may not be provided.
In
For example, in
A method of manufacturing the diaphragm units 80 and 82 is not limited to a method of forming diaphragm units 80 and 82 separately from the light transmitting member 30 or the like as in
In this embodiment, the diaphragm units 80 and 82 and the light shielding unit 100 may be integrally formed as a light shielding member 78. That is, the diaphragm units 80 and 82 and the light shielding unit 100 (light shielding wall) have an integral structure.
As shown in
As shown in
The height of the light shielding unit 100 in the direction DRH (see
The light shielding member 78 is attached toward the substrate 160 from the top (direction DRH) of the substrate 160 on which the light receiving unit 140 and the light emitting unit 150 are mounted (
It is preferable that processing for improving optical efficiency or performance of the pulse wave sensor is performed on the diaphragm units 80 and 82 and the light shielding unit 100. For example, processing for roughening the surfaces (wall surface) of the diaphragm units 80 and 82 and the light shielding unit 100 is performed, thereby suppressing reflectance of light. Alternatively, the surfaces of the diaphragm units 80 and 82 and the light shielding unit 100 has a moth eye structure. For example, a rugged structure in a cycle of tens to hundreds of nm is formed on the surface to form a reflection prevention structure. Alternatively, the color of the surfaces of the diaphragm units 80 and 82 and the light shielding unit 100 is a predetermined color, such as black, thereby preventing irregular reflection. With this configuration, it is possible to effectively suppress a situation in which reflected light in the diaphragm units 80 and 82 and the light shielding unit 100 becomes stray light, and stray light becomes the noise component of measured data.
As described above, in order to improve optical efficiency or performance of the pulse wave sensor, it is preferable to minimize the distance between the light receiving unit 140 and the light emitting unit 150. For this reason, it is necessary that the light shielding unit 100 has a wall-thickness structure as thin as possible. In particular, in the center portion 102 (a region intersecting a line which connects the center position of the light receiving unit 140 and the center position of the light emitting unit 150) of the light shielding unit 100 of
However, in a single structure of the light shielding unit 100 whose wall thickness is thin, strength is lacking. For example, during traveling in which the pulsimeter is used or during cycling, since strong impact (for example, about 10 G) is applied to the apparatus, enough strength to cope with this impact is required.
Accordingly, in
Since the diaphragm units 80 and 82 and the light shielding unit 100 are identical in terms of optical stabilization, the materials are readily shared. For example, it becomes easy to set the color of the surfaces of the diaphragm units 80 and 82 and the light shielding unit 100 in black so as to suppress the occurrence of irregular reflection.
The diaphragm units 80 and 82 and the light shielding unit 100 are integrally formed, thereby improving ease of assembling during component assembling and contributing to reduction in cost. For example, the light shielding member 78 is inserted into the concave portion 32 of the light transmitting member 30, the protrusions 86 and 88 of the light shielding member 78 are fixed to be engaged with the substrate 160 having the light receiving unit 140 and the light emitting unit 150 mounted thereon, thereby completing assembling of the pulse wave sensor.
Taking the productivity of the apparatus into consideration, it is preferable to manufacture the light shielding member 78 by injection molding. However, if the wall thickness of the light shielding unit 100 is too thin, during injection molding, there is a possibility that resin is not sufficiently filled in the portion of the light shielding unit 100.
Accordingly, in
In
For example, if the area of the opening 83 on the light emitting unit side is small, the paths of DP1 and DP2 of
In this way, if the area of the opening 83 on the light emitting unit side is small to allow resin to easily flow, and the wall thickness in the center portion 102 of the light shielding unit 100 or the like is thin, it is possible to decrease the distance between the light receiving unit 140 and the light emitting unit 150. Accordingly, it is possible to improve optical efficiency or performance. That is, it becomes possible to prevent resin from being not sufficiently filled during injection molding and to achieve improvement of yield or the like while achieving both strength and optical efficiency or performance of the light shielding unit 100.
The detection unit 130 detects biological information, such as a pulse wave, and includes a light receiving unit 140 and a light emitting unit 150. A pulse wave sensor (photoelectric sensor) is realized by the light receiving unit 140, the light emitting unit 150, and the like. The detection unit 130 outputs a signal detected by the pulse wave sensor as a pulse wave detection signal.
The body motion detection unit 190 outputs a body motion detection signal, which is a signal with change according to a body motion, on the basis of sensor information of various sensors. The body motion detection unit 190 includes, for example, an acceleration sensor 192, as a body motion sensor. The body motion detection unit 190 may have a pressure sensor or a gyro sensor as a body motion sensor.
The processing unit 200 performs various kinds of signal processing or control processing with the storage unit 240 as a work area, and can be realized by, for example, a processor, such as a CPU, or a logic circuit, such as an ASIC. The processing unit 200 includes a signal processing unit 210, a pulsation information calculation unit 220, and a display control unit 230.
The signal processing unit 210 performs various kinds of signal processing (filtering and the like), and performs signal processing on, for example, the pulse wave detection signal from the detection unit 130, the body motion detection signal from the body motion detection unit 190, or the like. For example, the signal processing unit 210 includes a body motion noise reduction unit 212. The body motion noise reduction unit 212 performs processing for reducing (eliminating) body motion noise as noise due to a body motion from the pulse wave detection signal on the basis of the body motion detection signal from the body motion detection unit 190. Specifically, for example, noise reduction processing using an adaptive filter or the like is performed.
The pulsation information calculation unit 220 performs calculation processing of pulsation information on the basis of a signal from the signal processing unit 210 or the like. The pulsation information is, for example, information, such as a pulse rate. Specifically, the pulsation information calculation unit 220 performs frequency analysis processing, such as FFT, on the pulse wave detection signal after the noise reduction processing in the body motion noise reduction unit 212 to obtain a spectrum, and performs processing for defining a representative frequency in the obtained spectrum as the frequency of heartbeat. A value 60 times the obtained frequency becomes a pulse rate (heart rate) which is generally used. The pulsation information is not limited to the pulse rate, and for example, various other kinds of information (for example, the frequency, cycle, or the like of heartbeat) representing the pulse rate may be used. Information representing the state of pulsation may be used, and for example, a value representing a blood volume may be used as the pulsation information.
The display control unit 230 performs display control for displaying various kinds of information or images on the display unit 310. For example, as shown in
Although this embodiment has been described above in detail, it can be easily understood by those skilled in the art that many modifications may be made without departing from the new matter and effects of the invention in a substantive way. Accordingly, such modifications still fall within the scope of the invention. For example, in the specification or the drawings, there are some terms which are presented at least once together with other terms which have a broader meaning or the same meaning, and each of these terms can be replaced with the other corresponding term at any location in the specification and the drawings. The configuration and operation of the biological information detection apparatus are not limited to those described in this embodiment, and various modifications may be made.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-054492 | Mar 2013 | JP | national |
| 2013-054493 | Mar 2013 | JP | national |
