Source: https://patents.google.com/patent/EP2340764A1/en
Timestamp: 2019-12-16 11:42:40
Document Index: 268545255

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EP2340764A1 - Biological information detector and biological information measurement device - Google Patents
EP2340764A1
EP2340764A1 EP20100197367 EP10197367A EP2340764A1 EP 2340764 A1 EP2340764 A1 EP 2340764A1 EP 20100197367 EP20100197367 EP 20100197367 EP 10197367 A EP10197367 A EP 10197367A EP 2340764 A1 EP2340764 A1 EP 2340764A1
EP20100197367
2010-12-30 Application filed by Seiko Epson Corp filed Critical Seiko Epson Corp
2011-07-06 Publication of EP2340764A1 publication Critical patent/EP2340764A1/en
239000000758 substrates Substances 0 description 73
230000001012 protector Effects 0 description 39
A biological information detector includes a first sensor unit for detecting composite information including biological information of a detection site of a test subject and first noise information originating in external light, and a second sensor unit for detecting second noise information originating in the external light. The first sensor unit has a light-emitting part for emitting a first light toward the detection site, a first light-receiving part for receiving the light including the biological information obtained from the first light emitted toward the detection site being reflected by the detection site, and the light including the first noise information obtained from the external light being transmitted through the test subject, and a first reflecting part for reflecting the light including the biological information and the light including the first noise information and leading the light to the first light-receiving part. The second sensor unit has a second light-receiving part for receiving the light including the second noise information obtained from the external light being transmitted through the test subject, and a second reflecting part for reflecting the light including the second noise information and leading the light to the second light-receiving part.
According to a second aspect of the present invention, a relation S2 < S1 may be satisfied, where S1 is an area of a reflecting surface of the first reflecting part, and S2 is an area of a reflecting surface of the second reflecting part.
Because the first sensor unit has a light-emitting part, a part of the external light transmitted through the test subject is blocked or reflected by the light-emitting part, and is suppressed from reaching the first reflecting part. That is, the amount of external light reaching the first reflecting part is made less than the amount of external light reaching the second reflecting part, by the amount blocked or reflected by the light-emitting part. Therefore, by satisfying the relation S2 < S1, the amount of external light transmitted through the test subject is suppressed from reaching the second reflecting part, by the amount of reduction of area (S1 - S2) of the reflecting surface of the second reflecting part. The difference between the amount of external light received by the second light-receiving part and the amount of external light received by the first light-receiving part can thus be reduced. The first noise information detected by the first sensor unit and the second noise information detected by the second sensor unit can thereby be more accurately corrected or cancelled, and the detecting accuracy of the biological information detector is further improved.
Because a first sensor unit has a light-emitting part (and a third reflector), a part of the external light transmitted through the test subject is blocked or reflected by the light-emitting part (or the third reflector), and is suppressed from reaching the first reflecting part. That is, the amount of external light reaching the first reflecting part is made less than the amount of external light reaching the second reflecting part, by the amount blocked or reflected by the light-emitting part (or the third reflector), Therefore, by the presence of the fourth reflector (dummy reflector), the part of the external light transmitted through the test subject is suppressed from reaching the second reflecting part, by being blocked or reflected by the fourth reflector. The difference between the amount of external light received by the second light-receiving part and the amount of external light received by the first light-receiving part can thus be reduced. The first noise information detected by the first sensor unit and the second noise information detected by the second sensor unit can thereby be more accurately corrected or cancelled, whereby the detecting accuracy of the biological information detector is further improved.
Because the first sensor unit has a first wiring to the light-emitting part, the amount of external light transmitted through the test subject is blocked or reflected by the wiring to the light-emitting part, and is suppressed from reaching the first reflecting part. Specifically, the amount of external light reaching the first reflecting part is made less than the amount of external light reaching the second reflecting part, by the amount blocked or reflected by the wiring to the light-emitting part. Therefore, by the presence of the pseudo-wiring, the part of the external light transmitted through the test subject is suppressed from reaching the second reflecting part, by being blocked or reflected by the pseudo-wiring. The difference between the amount of eternal light received by the second light-receiving part and the amount of external light received by the first light-receiving part can thus be reduced. The first noise information detected by the first sensor unit and the second noise information detected by the second sensor unit can thereby be more accurately corrected or cancelled, whereby the detecting accuracy of the biological information detector is further improved.
According to a sixth aspect of the present invention: the first reflecting part may be formed as a spherical surface or a parabolic surface; the second reflecting part may be formed as a spherical surface or a parabolic surface; and a relation Δhc > Δh may be satisfied, where Δh is a distance between a light-receiving surface of the first light-receiving part and a center of an arc defining the spherical surface of the first reflecting part or a focus of a parabola defining the parabolic surface of the first reflecting part, and Δhc is a distance between a light-receiving surface of the second light-receiving part and a center of an arc defining the spherical surface of the second reflecting part or a focus of a parabola defining the parabolic surface of the second reflecting part.
Thus, by satisfying the relation Δhc > Δh, the difference between the amount of external light received by the second light-receiving part and the amount of external light received by the first light-receiving part can be reduced. The first noise information detected by the first sensor unit and the second noise information detected by the second sensor unit can be more accurately corrected or cancelled, whereby the detecting accuracy of the biological information detector is further improved.
A seventh aspect of the present invention relates to a biological information, measurement device, characterized in comprising: a biological information detector described above; and a biological information measurement unit for measuring the biological information on the basis of signals generated in the first light-receiving part and signals generated in the second light-receiving part.
In FIG. 1, the detecting light-emitting part 14-1 emits light R1 toward a detection site O. The detecting light-receiving part 16-1 receives light R1' containing biological information obtained by the light R1 (reflected light) emitted toward the detection site O being reflected by the detection site O, and light R3' (transmitted light: noise) containing first noise information, obtained from external light R3 being transmitted through a test subject (e.g., user). The detecting reflector 18-1 reflects the light R1' (reflected light) containing the biological information from the detection site O and the light R3' (transmitted light) containing the first noise information from inside the test subject, and leads the light to the detecting light-receiving part 16-1. The detecting reflector 18-1 may have a reflecting surface on a domed surface provided on an optical path between the detecting light-emitting part 14-1 and the detecting light-receiving part 16-1. The first sensor unit is used for detecting composite information including the biological information in the detection site of the test subject and the first noise information originating in the external light R3.
The correcting light-receiving part 16-2 receives the light R3' (transmitted light: noise) containing second noise information obtained from the external light R3 being transmitted through the test subject. The correcting reflector 18-2 reflects the light R3' containing the second noise information from inside the test subject, and leads the light to the correcting light-receiving part 16-2. The correcting reflector 18-2 may have a reflecting surface on a domed surface provided on an optical path between the detection site O and the correcting light-receiving part 16-2. The correcting sensor unit is used for detecting the second noise information originating in the external light R3. The correcting sensor unit does not necessarily require a light-emitting part such as the detecting light-emitting part 14-1 of the first sensor unit.
In the example in FIG. 1, the detection site O (e.g., a blood vessel) is inside the test subject. The first light R1 enters into the test subject, and is diffused or scattered in the epidermis, dermis, and hypodermis. The first light R1 then reaches the detection site O, and is reflected by the detection site O. The light R1' reflected by the detection site O is diffused or scattered by the hypodermis, dermis, and epidermis, and proceeds toward the detecting reflector 18-1. The first light R1 is partially absorbed by the blood vessel. Accordingly, the absorption rate in the blood vessel changes due to an effect of the pulse, and the amount of light R1' reflected by the detection site O also changes. The biological information (e.g., the pulse count) thus is reflected in the light R1' reflected by the detection site O.
On the other hand, the external light R3 (e.g., sunlight) is diffused or scattered inside the test subject. The transmitted light R3' transmitted through the test subject without reaching the detection site O proceeds toward the detecting reflector 18-1 or the correcting reflector 18-2. Accordingly, the biological information (pulse count) is not reflected in the transmitted light R3' transmitted through the test subject. The external light R3 is also diffused or scattered inside the test subject, for example, in locations where tendons, bones, or other obstructions are not present, and noise information is therefore reflected in the transmitted light R3' transmitted through the test subject.
In the example in FIG. 1, the first light R1 is reflected also by an outer surface (skin surface) SA of the test subject. In the case when the detection site O is inside the test subject, the biological information (pulse count) is not reflected in the light R1" (directly reflected light) reflected by the outer surface SA of the test subject. In the example in FIG. 1, the reflected light R1" (in the broad sense, noise) is prevented from reaching the correcting light-receiving part 16-2.
In FIG, 1, the reflected light R1' (valid light) reflected by the detection site O reaches the detecting light-receiving part 16-1 by way of the detecting reflector 18-1, but is suppressed from reaching the correcting light-receiving part 16-2. Accordingly, the detecting light-receiving part 16-1 efficiently receives the light emitted by the detecting light-emitting part 14-1, but the correcting light-receiving part 16-2 receives almost no light emitted by the detecting light-emitting part 14-1. The external light R3 has a wavelength of 700 [nm] to 1100 [nm] that is easily transmitted through the so-called "biological window," and the transmitted light R3' (in the broad sense, noise) transmitted through the test subject reaches the detecting reflector 18-1 and the correcting reflector 18-2. The correcting light-receiving part 16-2 thus is independent from the detecting light-receiving part 16-1, and can efficiently sense the second noise information originating in the external light R3 transmitted through the test subject. Here, the transmitted light R1' containing the first noise information obtained from the external light R3 being transmitted through the test subject also is received by the detecting light-receiving part 16-1, but the biological information in the detection site O can be efficiently detected upon correction or cancellation of the first noise information by the second noise information. The detecting accuracy (S/N ratio) of the biological information detector is thereby improved. In the case when the reflecting surface of the detecting reflector 18-1 is a domed surface, the reflected light R1' reflected by the detection site O is more easily condensed on the detecting light-receiving part 16-1, and the reflected light R1' can be made less likely to reach the correcting light-receiving part 16-2 to that extent. In such case, the detecting accuracy (S/N ratio) of the biological information detector is further increased.
For example, the detecting light-emitting part 14-1 is an LED. For example, the maximum value (in the broad sense, peak value) of intensity of light emitted by an LED is in a wavelength range from 425 [nm] to 625 [nm]. For example, green light is emitted. For example, the thickness of the detecting light-emitting part 14-1 is 20 [µm] to 1000 [µm]. For example, the detecting light-receiving part 16-1 is a photodiode, and generally can be configured with a Si photodiode. For example, the thickness of the detecting light-receiving part 16-1 is 20 [µm] to 1000 [µm]. For example, the maximum value (in the broad sense, peak value) of sensitivity to light received by a Si photodiode is in a wavelength range from 800 [nm] to 1000 [nm]. Preferably, the detecting light-receiving part 16-1 is configured with a GaAsP photodiode, and for example, the maximum value (in the broad sense, peak value) of sensitivity to light received by a GaAsP photodiode is in a wavelength range from 550 [nm] to 650 [nm]. A biological substance (water or hemoglobin) easily transmits infrared radiation included in a range of 700 [nm] to 1100 [nm], and a detecting light-receiving part configured with a GaAsP photodiode is therefore more capable of reducing the noise component originating in the external light, for example, compared with a light-receiving part 16-1 configured with a Si photodiode.
FIG. 3 illustrates an example of the sensitivity characteristics to light received by the detecting light-receiving part 16-1. In the example in FIG. 3, the maximum value of sensitivity is indicated for light having a wavelength of 565 [nm], and the sensitivity to light in other wavelengths is normalized by that sensitivity. The maximum value of sensitivity to wavelength of light received by the detecting light-receiving part 16-1 illustrated in FIG. 3 is within the wavelength range of light emitted by the detecting light-emitting part 14-1 illustrated in FIG. 2, but is not within the range of 700 [nm] to 1100 [nm] referred to as the "biological window." In the example in FIG. 3, the sensitivity to infrared radiation included in the range from 700 [nm] to 1100 [nm] is set to a relative sensitivity of 0.3 (30 [%]) or lower. The maximum value (e.g., 565 [nm]) of sensitivity to wavelength of light received by the detecting light-receiving part 16-1 is preferably closer to the maximum value (520 [nm]) of the intensity of the wavelength of light emitted by the light-emitting part 14 from the 700 [nm] lower limit of the biological window.
FIG. 4 illustrates another example of the configuration of the first sensor unit. As illustrated in FIG. 4, the first sensor unit of the biological information detector may include a detecting reflector 42-1 (corresponding to the third reflector) for reflecting light. Identical reference numerals are assigned to identical configurations with the above configuration example, and the description of the correcting sensor unit is omitted. In the following description, the detecting reflector 42-1 is referred to as "first detecting reflector," and the detecting reflector 18-1 in FIG. 1 is referred to as "second detecting reflector."
In the example in FIG. 4, the first sensor unit of the biological information detector includes a detecting light-emitting part 14-1, a first detecting reflector 42-1, a detecting light-receiving part 16-1, and a second detecting reflector 18-1. The detecting light-emitting part 14-1 emits a first light R1 toward the detection site O of the test subject (user), and a second light R2 toward a different direction (the first detecting reflector 42-1) than the detection site O. The first detecting reflector 42-1 reflects the second light R2 and leads the light to the detection site O. The detecting light-receiving part 16-1 receives lights R1' and R2' (reflected lights) containing the biological information obtained from the first light R1 and the second light R2 being reflected by the detection site O. The second detecting reflector 18-1 reflects the lights R1' and R2' (reflected lights) containing the biological information from the detection site O and leads the lights to the detecting light-receiving part 16-1. By the presence of the first detecting reflector 42-1, the second light R2 not directly reaching the detection site O of the test subject (user) also reaches the detection site O. In other words, the amount of light reaching the detection site O is increased by way of the first detecting reflector 42-1. Accordingly, the detecting accuracy (S/N ratio) of the biological information detector is improved.
In the example in FIG. 4, the second light R2 enters into the test subject, and the light R2' reflected by the detection site O proceeds toward the second detecting reflector 18-1. The biological information (pulse count) is reflected also in the light R2' reflected by the detection site O. In the example in FIG. 4, the first light R1 is partially reflected by the outer surface (skin surface) SA of the test subject. In the case when the detection site O is inside the test subject, the biological information (pulse count) is not reflected in the light R1" (directly reflected light) reflected by the outer surface SA of the test subject. In the example in FIG. 4, the transmitted light R3' transmitted through the test subject proceeds toward the same direction as the reflected light R1".
The wall part of the first detecting reflector 42 may further have a second reflecting surface (corresponding to the reference numeral 42C indicated in FIGS. 5(A) to (C) for reflecting light (invalid light: noise) not containing the biological information, reflected by the outer surface of the test subject, and thereby suppressing the light not including the biological information from being input to the detecting light-receiving part 16-1. The second reflecting surface (42C) can reflect also the transmitted light R3' and suppressing input to the detecting light-receiving part 16-1. The configuration example of the first sensor unit of the biological information detector is not limited by FIG. 4, and the shape, or the like, of a part (e.g., first detecting reflector 42-1) of the configuration example may be modified.
FIGS. 5(A), (B), and (C) illustrate an example of the configuration of the first detecting reflector 42-1 in FIG. 4. As illustrated in FIG. 5(A), the first detecting reflector 42-1 may have a support part 42A for supporting the detecting light-emitting part 14-1, and an inner wall surface 42B and a top surface 42C of a wall part surrounding the second light-emitting surface 42B of the detecting light-emitting part 14-1. In FIGS. 5(A) to (C), the detecting light-emitting part 14-1 is omitted. In the example in FIG. 5(A), the first detecting reflector 42-1 can reflect the second light R2 on the inner wall surface 42B to the detection site O (see FIG. 4), and has a first reflecting surface on the inner wall surface 42B. For example, the thickness of the support part 42A is 50 [µm] to 1000 [µm], and for example, the thickness of the wall part (42C) is 100 [µm] to 1000 [µm].
In the example in FIG. 5(A), the inner wall surface 42B has an inclined surface (42B) that is displaced toward the side of the detection site O in a height direction (a direction perpendicular to a first direction) while going away from the center of the first detecting reflector 42 in a width direction (the first direction) in sectional view. The inclined surface (42B) in FIG. 5(A) is formed as an inclined plane, but may be formed as a curved surface or other inclined surface. The inner wall surface 42B may be formed as a plurality of inclined planes having different angles of inclination, or may be formed as curved surfaces having a plurality of curvatures. In the case when the inner wall surface 42B of the first detecting reflector 42-1 has an inclined surface, the inner wall surface 42B of the first detecting reflector 42-1 can reflect the second light R2 toward the detection site O. In other words, the inclined surface of the inner wall surface 42B of the first detecting reflector 42-1 may be considered as a first reflecting surface for increasing the directionality of the detecting light-emitting part 14-1. In this case, the amount of light reaching the detection site O is further increased. The top surface 42C in FIGS. 5(A) and (C) may be omitted, for example, as illustrated in FIG. 5(B). In the case when the first detecting reflector 42-1 has a top surface 42C, the light R1" (directly reflected light) reflected by the outer surface SA of the test subject can be reflected to the detection site or the periphery thereof, and the reflected light R1" can be suppressed from reaching the detecting light-receiving part 16-1 (see FIG. 4). In short, the top surface 42C in FIGS. 5(A) and (C) can be considered as a second reflecting surface for reflecting the directly reflected light (in the broad sense, noise) that would reach the second detecting reflector 18-1 and the detecting light-receiving part 16-1, and reducing the noise. In FIGS. 5(A) and (C), the range indicated by the reference numeral 42D functions as a mirror surface.
In the example in FIG. 4, the first detecting reflector 42-1 may project toward the detection site O, for example, by a given height (e.g., Δh1 = 50 [µm] to 950 [µm]) with reference to the surface of the detecting light-emitting part 14-1 defining the shortest distance from the outer surface SA of the test subject. In other words, a gap (e.g., Δh2 = Δh0 - Δh1 = 200 [µm] to 1200 [µm]) between the first detecting reflector 42-1 and the outer surface SA of the test subject can be made smaller than a gap (e.g., Δh0 = Δh1 + Δh2) being between the detecting light-emitting part 14-1 and the outer surface SA of the test subject. Accordingly, the area of the reflecting surface (42B) of the first detecting reflector 42-1 can be increased, for example, by the presence of the protruding amount Δh1 from the detecting light-emitting part 14-1, and the amount of light reaching the detection site O can be increased. An optical path for the light reflected on the detection site O to reach the second detecting reflector 18-1 from the detection site O can be secured by the presence of the gap Δh2 between the first detecting reflector 42-1 and the outer surface SA of the test subject. In the case when the first detecting reflector 42-1 has a second reflecting surface (92C), the amounts of light (valid light) containing the biological information and light (invalid light; noise) not containing the biological information input to the detecting light-receiving part 16-1 can be respectively adjusted by adjusting Δh1 and Δh2, whereby the S/N can be further improved.
FIGS. 6(A) and (B) illustrate an example of the external appearance in plan view of the first detecting reflector 42-1 and the detecting light-emitting part 14-1 in FIG. 4. In the example in FIG. 6(A), the outer perimeter of the first detecting reflector 42-1 expresses a circle in plan view (e.g., on the side of the detection site O in FIG. 4), and, for example, the diameter of the circle is 200 [µm] to 11000 [µm]. In the example in FIG. 6(A), the wall part (42B) of the first detecting reflector 42-1 surrounds the detecting light-emitting part 14-1 (see FIGS. 4 and 5(A)). The outer perimeter of the first detecting reflector 42-1 expresses a quadrangular shape (in the narrow sense, a square shape) in plan view, for example, as illustrated in FIG. 6(B). In the example in FIGS. 6(A) and (B), the outer perimeter of the detecting light-emitting part 14-1 expresses a quadrangular shape (in the narrow sense, a square shape) in plan view (e.g., on the side of the detection site O in FIG. 4), and, for example, one side of the square shape is 100 [µm] to 10000 [µm]. The outer perimeter of the detecting light-emitting part 14-1 may describe a circular shape.
The first detecting reflector 42-1 itself is forked with metal, and the top surface is mirror-finished to have a reflective structure (in the narrow sense, a mirror-reflective structure). The first detecting reflector 42-1 may be formed, for example, with resin, and the top surface may be mirror-finished. Specifically, for example, a metal undercoating of the first detecting reflector 42-1 is prepared, and then, for example, the top surface is plated. Or, for example, a thermoplastic resin is filled into a mold (not illustrated) of the first detecting reflector 42-1, and then, for example, a metal film is vapor-deposited on the top surface.
In the example in FIGS. 5(A), (B), and (C), the mirror surface part 42D preferably has high reflectivity. For example, the reflectivity of the mirror surface part 42D is 80% to 90% or higher. The mirror surface part 42D may be formed only on the inclined surface of the inner wall surface 428. In the case when the mirror surface 42D is formed not only on the inclined surface, but also on the support part 42A, the directionality of the detecting light-emitting part 14 becomes even higher. In the case when the mirror surface part 42D is forme on the top surface 42C, the first detecting reflector 42-1 can reflect the light R1" (directly reflected light: invalid light) reflected by the outer surface SA of the test subject to the detection site O or the periphery thereof, and the reflected light R1" can be suppressed from reaching the second detecting reflector 18-1 and the detecting light-receiving part 16-1, for example, as illustrated in FIG. 4. Because the directionality of the detecting light-emitting part 14-1 becomes higher, and because the directly reflected light (in the broad sense, noise) is reduced, the detecting accuracy of the "biological information detector is improved.
In the example in FIG. 4, the transmitted light R3' transmitted trough the test subject proceeds in the same direction as the reflected light R1". That is, by the presence of the first detecting reflector 42-1, the transmitted light R3' transmitted through the test subject is suppressed from reaching the second detecting reflector 18-1. Likewise, by the presence of the detecting light-emitting part 14-1, the transmitted light R3' transmitted through the test subject is suppressed from reaching the second detecting reflector 18-1. For example, in the case when the detecting light-emitting part 14-1 in FIG. 1 is as large as the first detecting reflector 42-1 in FIG. 4, the transmitted light R3' transmitted through the test subject is blocked or reflected by the detecting light-emitting part 14-1, and is suppressed from reaching the second detecting reflector 18-1. That is, the amount of transmitted light R3' (external light) reaching the second detecting reflector 18-1 is made less than the amount of transmitted light R3' (external light) reaching the correcting reflector, by the amount blocked or reflected by the detecting light-emitting part or the first detecting reflector.
Then, in the example in FIG. 1, a relation S2 < S1 may be satisfied, for example, as in the example in FIG. 8, where S1 is the area of the reflecting surface of the detecting reflector 18-1 (second detecting reflector 18-1 in FIG. 4), and S2 is the area of the reflecting surface of the correcting reflector 18-2. In the case when the relation S2 < S1 is satisfied, the transmitted light R3' transmitted through the test subject can be suppressed from reaching the correcting reflector 18-2, by the amount of reduction of area (S1 - S2) of the reflecting surface of the correcting reflector 18-2. In other words, the amount of transmitted light R3' (external light) reaching the correcting reflector 18-2 is reduced by the amount of reduction of area (S1 - S2) of the correcting reflector 18-2. In the case when S1 = S2, as previously described, the amount of transmitted light R3' (external light) reaching the second detecting reflector 18-1 becomes less than the amount of transmitted light R3' (external light) reaching the correcting reflector 18-2, and therefore the difference between the amount of transmitted light R3' (external light) received by the correcting light-receiving part 16-2 and the amount of transmitted light R3' (external light) received by the detecting light-receiving part 16-1 can be reduced by reducing the amount of transmitted light R3' (external light) reaching the correcting reflector 18-2.
FIG. 7 illustrates another example of the configuration of the biological information detector of the present embodiment. As illustrated in FIG. 7, the correcting sensor unit of the biological information detector may have a dummy reflector 42-2 (corresponding to the fourth reflector) for reflecting a part of the transmitted light R3' (external light) transmitted through the test subject and suppressing the transmitted light R3' from reaching the correcting light-receiving part 16-2. Identical reference numerals are assigned to identical configurations with the above-described configuration example, and the description is omitted. The dummy reflector 42-2 is referred to as "first correcting reflector," and the correcting reflector 18-2 is referred to as "second correcting reflector." In the example in FIG. 7, because the correcting sensor unit does not have a light-emitting part such as the detecting light-emitting part 14-1 of the first sensor unit, the dummy reflector 42-2 (first correcting reflector) is originally not required. However, by the presence of the dummy reflector 42-2 (first correcting reflector), a part of the transmitted light R3' (external light) transmitted through the test subject is suppressed from reaching the correcting reflector 18-2 (second correcting reflector). In other words, even in the case when the area (S1) of the reflecting surface of the detecting reflector 18-1 (second detecting reflector) is equal to the area (S2) of the correcting reflector 18-2 (second correcting reflector), the substantial area (S2') of the reflecting surface of the correcting reflector 18-2 (second correcting reflector) is reduced by the presence of the dummy reflector 42-2 (first correcting reflector). The difference between the amount of transmitted light R3' (external light) received by the correcting light-receiving part 16-2 and the amount of transmitted light R3' (external light) received by the detecting light-receiving part 16-1 can thus be reduced, or the difference can be brought substantially to zero.
FIG. 8 illustrates another example of the configuration of the biological information detector of the present embodiment. As illustrated in FIG. 8, the biological information detector may further include a substrate 81 having a first surface (e.g., top surface) and a second surface (e.g., bottom surface) opposed to the first surface. Identical reference numerals are assigned to identical configurations with the above-described configuration example, and the description is omitted. The detecting light-receiving part 16-1 and the correcting light-receiving part 16-2 are disposed on the first surface, and the first detecting reflector 42-1 is disposed on the second surface. A relation W1 ≤W2 may be satisfied, where W1 is the maximum length of the first detecting reflector 42-1 in a direction parallel to the first surface in sectional view, and W2 is the maximum length of the detecting light-receiving part 16 in that direction.
For example, the substrate 81 is made of a transparent material (e.g., polyimide), and transmits the reflected light R1' of the first light R1 emitted to the detection site O. The amount of light reaching the second detecting reflector 18-1 can be increased by setting the maximum length W1 of the first detecting reflector 42-1 to the maximum length W2 of the light-receiving part 16 or lower. In other words, the maximum length W1 of the first detecting reflector 42-1 can be set so that the reflected light R1' on the detection site O is not blocked or reflected by the first detecting reflector 42-1. For example, the thickness of the substrate 81 is 10 [µm] to 1000 [µm]. A wiring to the detecting light-emitting part 14-1, a wiring to the detecting light-receiving part 16-1, and a wiring to the correcting light-receiving part 16-2 may be formed on the board. For example, the substrate 81 is a printed board, but a printed board is not usually made of a transparent material. In other words, the present inventors ventured to constitute a printed board with a material that is at least transparent to the wavelength of light emission of the detecting light-emitting part 14-1.
In the example in FIG. 8, the second light R2 emitted by way of the first detecting reflector 42-1, the reflected light R2' on the detection site O, the light R1" (directly reflected light) reflected by the outer surface SA of the test subject, or the transmitted light R3' transmitted through the test subject are omitted (see FIG. 4). Persons skilled in the art should be able to easily understand the path for the second light R2, the correct path for the first light R1, or the correct path for the external light R3.
As illustrated in FIG. 8, the biological information detector may include a protector 89 for protecting the first detecting reflector 42-1 and the detecting light-emitting part 14-1. For example, the protector 89 is made of a transparent material (e.g., glass), and transmits the first light R1 emitted to the detection site O and the (reflected light R1' of the first light R1. The protector 89 may ensure a gap (e.g., Δh2) is present between the first detecting reflector 42-1 and the detection site O. A gap (e.g., Δh2') between the first detecting reflector 42-1 and the protector 89 is also present. For example, the thickness of the protector 89 is 1 [µm] to 1000 [µm].
In the example in FIG. 8, a relation S2 < S1 may be satisfied, where S1 is the area of the reflecting surface of the second detecting reflector 18-1, and S2 is the area of the reflecting surface of the correcting reflector 18-2. By satisfying the relation S2 < S1, the transmitted light R3' transmitted through the test subject is suppressed from reaching the correcting reflector 18-2, by the amount of reduction of area (S1 - S2) of the reflecting surface of the correcting reflector 18-2. In the case when S1 = S2, the amount of transmitted light R3' (external light) reaching the second detecting reflector 18-1 becomes less than the amount of transmitted light R3' (external light) reaching the correcting reflector 18-2, by the amount of transmitted light R3' (external light) blocked by the first detecting reflector 42-1 and the detecting light-emitting part 14-1. Therefore, the difference between the amount of transmitted light R3' (external light) received by the correcting light-receiving part 16-2 and the amount of transmitted light R3' (external light) received by the detecting light-receiving part 16-1 can be reduced by reducing the amount of transmitted light R3' (external light) reaching the correcting reflector 18-2.
FIG. 9 illustrates an example of the external appearance of the detecting light-receiving part 16-1 in FIG. 8. In the example in FIG. 9, the outer perimeter of the detecting light-receiving part 16-1 expresses a quadrangular shape (in the narrow sense, a square shape) in plan view (e.g., on the side of the second detecting reflector 18-1 in FIG. 8), and for example, one side of the square shape is 104 [µm] to 10000 [µm]. The outer perimeter of the first detecting reflector 42-1 describes a circle in plan view (e.g., on the side of the second detecting reflector 18-1 in FIG. 8). The outer perimeter of the first detecting reflector 42-1 may describe a quadrangular shape (in the narrow sense, a square shape) as in the example in FIG. 6(B). The outer perimeter of the detecting light-receiving part 16-1 may describe a circular shape.
In the example in FIG. 9, a relation W1 ≤W2 may be satisfied, where W1 is the maximum length of the first detecting reflector 42-1, and W2 is the maximum length of the detecting light-receiving part 16-1, as indicated by the line segment A-A'. The sectional view along the line segment A-A' in FIG. 9 corresponds to FIG. 8. The sectional view along the line segment B-B' in FIG. 9 is similar to FIG. 7, and the maximum length W1 of the first detecting reflector 42-1 is longer than the minimum length of the detecting light-receiving part 16-1. The maximum length W1 of the first detecting reflector 42-1 may be set to the minimum length of the detecting light-receiving part 16-1 or shorter, but the efficiency of the first detecting reflector 42-1 (in the broad sense, the efficiency of the detecting light-emitting part 14-1) is reduced. In the example in FIG. 9, the maximum length W1 of the first detecting reflector 42-1 is set to maximum length W2 of the detecting light-receiving part 16-1 or shorter, and the maximum length W1 of the first detecting reflector 42-1 is set larger than the minimum length of the detecting light-receiving part 16-1, so that the reflected light R1' is not blocked or reflected while the efficiency of the detecting light-emitting part 14-1 is maintained.
The biological information detector may further include an infrared-cutting filter 89-1. An infrared-cutting filter 89-1 is disposed on the optical path from the detecting light-emitting part 14-1 to the detecting light-receiving part 16-1. An infrared-cutting filter 89-1 is likewise disposed also on the optical path from the external light to the correcting light-receiving part 16-2. In the example in FIG. 10, an infrared-cutting filter 89-1 is formed on the contact surface of a detection protector 89-1A and on the contact surface of a correction protector 89-2A. In the example in FIG. 8, the contact surface of the detection protector 89-1A, and the correction protector 89-2A are formed as a single protector 89 (composite protector). The infrared-cutting filter 89-1 in FIG. 10 may be formed on the contact surface of the single protector 89. For example, the infrared-cutting filter 89-1 may be constituted by coating the contact surface of the detection protector 89-1A and the contact surface of the correction protector 89-2A with an infrared-absorbing material. In the case when the detection protector 89-1A and the correction protector 89-2A (single protector 89) are made of glass, the detection protector 89-1A and the correction protector 89-2A (single protector 89) having the infrared-cutting filter 89-1 may be referred to as "infrared-cutting glass." The infrared-cutting filter 89-1 may be formed on the entire surface on the outside of the detection protector 89-1A and on the entire surface on the outside of the correction protector 89-2A, rather than only on the contact surface of the detection protector 89-1A and the contact surface of the correction protector 89-2A. The infrared-cutting filter 89-1 may be formed on the entire surface on the inside of the detection protector 89-1A and on the entire surface on the inside of the correction protector 89-2A. Or, the infrared-cutting filter 89-1 may be formed on the surface of the substrate 81, the detecting light-receiving part 16-1 and on the surface of the correcting light-receiving part 16-2, instead of on the contact surface of the detection protector 89-1A and the contact surface of the correction protector 89-2A. Because a biological substance (water or hemoglobin) easily transmits infrared light, the noise component originating in the external light can be reduced by an infrared-cutting filter 89-1 disposed on the optical path from the detecting light-emitting part 14-1 to the detecting light-receiving part 16-1. In the correcting sensor unit, just as in the first sensor unit, the noise component originating in the external light can be reduced by disposing an infrared-cutting filter 89-1 on the optical path from the external light to the correcting light-receiving part 16-2.
FIG. 11 illustrates an example of the transmission characteristics of light through a substrate 81 coated with a light-transmitting film 81-1. In the example in FIG. 11, the transmittance is calculated by using the intensity of the light before transmission through the substrate 81 and the intensity of the light after transmission through the substrate 81. In the example in FIG. 11, the transmittance having a wavelength of 525 [nm] indicates the maximum value in the wavelength region at or below 700 [nm], being the lower limit of the biological window. Or, in the example in FIG. 11, the maximum value of transmittance of the light transmitted through the light-transmitting film 81-1 in the wavelength region at or below 700 [nm], being the biological window, for example, enters a range of within ±10% of the maximum value of the intensity of the wavelength of light emitted by the detecting light-emitting part 14-1 in FIG. 2. Thus, the light-transmitting film 81-1 is preferably one that selectively transmits the light emitted by the detecting light-emitting part 14-1 (e.g., the first light R1 in FIG. 10 (in the narrow sense, the reflected light R1' of the first light R1)). By the presence of the light-transmitting film 81-1, the flatness of the substrate 81 is improved, and a lowering of efficiency of the detecting light-emitting part 14-1 or the detecting light-receiving part 16-1 can be prevented to a certain extent. As illustrated in the example in FIG. 11, for example, in the case when the transmittance of the light having a wavelength of 525 [nm] indicates the maximum value (in the broad sense, peak value) in the visible light region, for example, the light-transmitting film 81-1 expresses green light.
FIG. 12 illustrates an example of the external appearance in plan view of the light-transmitting film 81-1 in FIG. 10. As illustrated in FIG. 12, the substrate 81 on which the light-transmitting film 81-1 is formed expresses a rectangular shape in plan view (e.g., on the side of the second detecting light-receiving part 16-1 in FIG. 10). In the example in FIG. 12, the detecting light-receiving part 16-1 and the correcting light-receiving part 16-2 are placed on the first surface (e.g., top surface) of the substrate 81. The light-transmitting film 81-1 maybe formed in a region of the first surface of the substrate 81 where the detecting light-receiving part 16-1 and the correcting light-receiving part 16-2 are not placed.
The composite reflector 18 can then be formed or fixed on the substrate 81 (and the light-transmitting film 81-1). As illustrated in FIG. 12, the external shape of the composite reflector 18 describes a quadrangular shape. The external shape of a boundary 18-1A between the reflecting surface (domed surface) of the second detecting reflector 18-1 of the composite reflector 18 and the substrate 81 (light-transmitting film 81-1) describes a circular shape. A boundary 18-2A between the reflecting surface (domed surface) of the correcting reflector 18-2 of the composite reflector 18 and the substrate 81 (light-transmitting film 81-1 also expresses a circular shape. The light-transmitting film 81-1 may be applied selectively only in the light-transmitting regions inside the boundary 18-1A (circular shape) and the boundary 18-2A (circular shape). In other words, the light-transmitting film 81-1 may be applied selectively only in the light-transmitting regions where the light received by the detecting light-receiving part 16-1 and the light received by the correcting light-receiving part 16-2 are transmitted.
In the example in FIG. 12, a pseudo-wiring 125 is formed on the second surface (e.g., bottom surface) of the substrate 81. By the presence of the pseudo-wiring 125, a part of the transmitted light R3' (external light) transmitted through the test subject is suppressed from reaching the correcting reflector 18-2. The difference between the amount of transmitted light R3' (external light) received by the correcting light-receiving part 16-2 and the amount of transmitted light R3' (external light) received by the detecting light-receiving part 16-1 can thus be reduced.
FIGS. 13(A) and (B) illustrate graphs for describing the infrared-cutting filter 89-1 in FIG. 10. FIG. 13(A) illustrates one example of the transmission characteristics of light passing through the protector 89 without the infrared-cutting filter 89-1. FIG. 13(B) illustrates one example of the transmission characteristics of light passing through an infrared-absorbing material constituting the infrared-cutting filter 89-1. Referring to FIGS. 13(A) and (B), light (e.g., external light) in a range from 700 [nm] to 1100 [nm], referred to as the "biological window," can be prevented from entering by the presence of the infrared-cutting filter 89-1. The infrared-cutting filter 89-1 may be used for preventing the entrance of only a part of the wavelength (e.g., 700 [nm] to 800 [nm]) in the range from 700 [nm] to 1100 [nm].
FIG. 15 is a diagram for describing the placement positions of the detecting reflector 18-1 and the correcting reflector 18-2 in FIG. 1, and the like. In FIG. 15, the detecting light-emitting part 14-1, and the like, in FIG. 1, and the like, are omitted. For example, the reflecting surface of the detecting reflector 18-1 (second detecting reflector 18-1) maybe constituted as a spherical surface (in the broad sense, domed surface) so that the reflected light R1' of the first light R1 on the detection site O is reflected to the detecting light-receiving part 16-1. As illustrated in FIG. 15, the reflecting surface of the detecting reflector 18-1 (second detecting reflector 18-1) expresses an arc in sectional view. For example, the radius of the arc is 1000 [µm] to 15000 [µm]. The center C of the arc defining the spherical surface is disposed inside the test subject. In the case when there is a detection site O inside the test subject, the light R1" (directly reflected light) reflected by the outer surface SA of the test subject is invalid light not including the biological information. The present inventors recognized that, in the case when the reflecting surface of the detecting reflector 18-1 (second detecting reflector 18-1) is constituted as a spherical surface and the center C of the arc defining the spherical surface is set inside the test subject, the light (in the broad sense, noise) reflected by the outer surface SA of the test subject is suppressed by the detecting reflector 18-1 (second detecting reflector 18-1). In FIG. 15, the distance between the light-receiving surface of the detecting light-receiving part 16-1 and the center C of the arc defining the spherical surface is indicated as Δh.
The reflecting surface of the detecting reflector 18-1 (second detecting reflector 18-1) may be constituted as a parabolic surface (in the broad sense, domed surface) instead of a spherical surface. As illustrated in FIG. 15, the reflecting surface of the detecting reflector 18-1 (second detecting reflector 18-1) describes an arc in sectional view, but may describe a parabola instead of an arc. In FIG. 15, assuming that the reflecting surface of the detecting reflector 18-1 (second detecting reflector 18-1) is a parabolic surface, the focus of the parabola defining the parabolic surface is indicated by the reference numeral F. The focus F of the parabola defining the parabolic surface is disposed toward the side of the test subject, with reference to the light-receiving surface of the detecting light-receiving part 16-1. Because the light perpendicular to the outer surface SA of the test subject is reflected by the reflecting surface (parabolic surface) of the detecting reflector 18-1 (second detecting reflector 18-1), and is resolved on the focus F of the parabola defining the parabolic surface, the light (e.g., the reflected light R1' (valid light) of the first light R1) close to the light perpendicular to the outer surface SA of the test subject is more easily condensed by arranging the focus F so as not to coincide with the light-receiving surface of the detecting light-receiving part 16-1.
The reflecting surface of the correcting reflector 18-2 may be formed, for example, as a domed surface (spherical surface or parabolic surface), just as the detecting reflector 18-1 (second detecting reflector 18-1). As illustrated in FIG. 15, the reflecting surface of the correcting reflector 18-2 describes an arc in sectional view, but may describe a parabola. In the case when the reflecting surface of the correcting reflector 18-2 describes an arc in sectional view, the radius of the arc of the correcting reflector 18-2 may be set equal to the radius of the arc of the detecting reflector 18-1 (second detecting reflector 18-1), or may be set smaller than that radius. In FIG. 15, the distance between the light-receiving surface of the correcting reflector 16-2 and the center C of the arc defining the spherical surface of the correcting light-receiving part 16-2 is indicated by Δhc. By satisfying the relation Δhc > Δh, the difference between the amount of transmitted light R3' (external light) received by the correcting light-receiving part 16-2 and the amount of transmitted light R3' (external light) received by the detecting reflector 18-1 (second detecting reflector 18-1) can be reduced. In other words, by satisfying the relation Δhc > Δsh, a relation S2 (area of the reflecting surface of the correcting reflector 18-2) < S1 (area of the reflecting surface of the detecting reflector 18-1 (second detecting reflector 18-1)) may also be satisfied. The relation S2 < S1 may be satisfied by setting the radius of the arc of the correcting reflector 18-2 smaller than the radius of the arc of the detecting reflector 18-1 (second detecting reflector 18-1).
For example, the detecting reflector 18-1 (second detecting reflector 18-1) is made of resin, and the top surface (the reflecting surface on the side of the detecting light-receiving part 16-1) is mirror-finished to have a reflective structure (in the narrow sense, a mirror-reflective structure). In other words, the detecting reflector 18-1 (second detecting reflector 18-1) may be rendered to mirror-reflect light and not to diffusely reflecting the light. In the case when the detecting reflector 18-1 (second detecting reflector 18-1) has a mirror-reflective structure, this detecting reflector 18-1 (second detecting reflector 18-1) can prevent reflection of the reflected light R1" (directly reflected light) of the first light R1, having a different angle of reflection from the angle of reflection of the reflected light R1' of the first light R1, to the detecting light-receiving part 16-1. In such a case, the detecting accuracy of the biological information detector is further improved. As illustrated in FIG. 15, because the origin of the reflected light R1' of the first light R1 is the detection site O inside the test subject, the angle of reflection of the reflected light R1' of the first light R1 is generally small. On the other hand, because the origin of the reflected light R1" of the first light R1 is the outer surface SA of the test subject, the angle of reflection of the reflected light R1" of the first light R1 is generally large. For example, the correcting reflector 18-2 also may be made of resin, and the top surface (the reflecting surface on the side of the correcting light-receiving part 16-2) may be mirror-finished to have a reflective structure (in the narrow sense, a mirror-reflective structure).
FIG. 16 is a graph of the relationship between the placement position of the detecting reflector 18-1 in FIG. 15 and the amount of light received by the detecting light-receiving part 16-1. As illustrated in FIG. 16, as the distance Δh between the light-receiving surface of the detecting light-receiving part 16-1 and the center C of the arc defining the spherical surface becomes greater, the light (in the broad sense, noise, for example, corresponding to the reflected light R1") directly reflected by the outer surface SA of the test subject decreases, and the light (in the broad sense, biological information, for example, corresponding to the reflected light R1') increases and then decreases. The position of Δh can therefore be optimized. In the case when the reflecting surface of the detecting reflector 18-1 (second detecting reflector 18-1) is a parabolic surface, the distance between the light-receiving surface of the detecting light-receiving part 16-1 and the focus F of the parabola defining the parabolic surface also can be optimized.
FIGS. 17(A) and (B) are examples of the external appearance of a biological information measurement device including the biological information detector in FIG. 1, and the like. As illustrated in FIG. 17(A), for example, the biological information detector in FIG. 1 may further include a wristband 170 attachable to an arm (in the narrow sense, wrist) of the test subject (user) of the biological information detector. In the example in FIG. 17(A), the biological information is a pulse count, for example, as indicated by "72." The biological information detector is incorporated in a wristwatch, and the time (e.g., 8:15 a.m.) is displayed. As illustrated in FIG. 17(B), two openings are provided on the back cover of the wristwatch, and for example, the detection protector 89-1 in FIG. 10 is exposed in one of the two openings. For example, the correction protector 89-2A is exposed in the other of the two openings. One opening may be provided on the back cover of the wristwatch, and for example, the single protector 89 (composite protector) in FIG. 18 may be exposed in that opening. In the example in FIG. 17(B), the second detecting reflector 18-1 (detecting reflector 18-1) and the detecting light-receiving part 16-1 are incorporated in the wristwatch, and the boundary 18-1A between the reflecting surface (domed surface) of the second detecting reflector 18-1 and the substrate 81 is depicted by a dotted line. The correcting reflector 18-2 and the correcting light-receiving part 16-2 also are incorporated in the wristwatch, and the boundary 18-2A between the reflecting surface (domed surface) of the correcting reflector 18-2 and the substrate 81 is depicted by a dotted line. In the example in FIG. 17(B), the first detecting reflector 42-1, the detecting light-emitting part 14-1, and the like, are omitted.
In the example in FIG. 17(B), the detecting light-receiving part 16-1 (in the broad sense, first sensor unit) and the correcting light-receiving part (in the broad sense, correcting sensor unit) are disposed along the direction of extension of the wristband 170. The external light R3 enters between the wristband 170 and the arm from the surface side of the arm (the side of the wrist on the side where the biological information detector is worn). As illustrated in FIG. 17(A), the external light R3 enters, for example, from the direction from the peripheral side (e.g., the side of the back of the hand) toward the central side (shoulder joint) in plan view. The transmitted light R3' transmitted through the test subject proceeds toward the detecting light-receiving part 16-1 and the correcting light-receiving part 16-2. Accordingly, the detecting light-receiving part 16-1 and the correcting light-receiving part 16-2 may be disposed along the direction of extension of the wristband 170, so that the transmitted light R3' (external light R3) equally enters both the correcting sensor unit and the first sensor unit.
The A/D conversion circuit 193 in FIG. 19 is used for converting AC signals generated in the amplification circuit 192 to digital signals (first digital signals). The acceleration rate sensor 96 is used for detecting the weight acceleration rate, for example, on three axes (X, Y, and Z axes), and to generate acceleration rate signals. Movement of the body (arm), and accordingly movement of the biological information measurement device, is reflected in the acceleration rate signals. The A/D conversion circuit 197 in FIG. 19 is used for converting the acceleration rate signals generated in the acceleration rate sensor 196 to digital signals (second digital signals).
A biological information detector comprising:
a first sensor unit for detecting composite information including biological information of a detection site of a test subject and first noise information originating in external light; and
a second sensor unit for detecting second noise information originating in the external light;
a light-emitting part for emitting a first light toward the detection site,
a first light-receiving part for receiving the light including the biological information obtained from the first light emitted toward the detection site being reflected by the detection site, and the light including the first noise information obtained from the external light being transmitted through the test subject, and
a first reflecting part for reflecting the light including the biological information and the light including the first noise information and leading the light to the first light-receiving part;
a second light-receiving part for receiving the light including the second noise information obtained from the external light being transmitted through the test subject, and
a second reflecting part for reflecting the light including the second noise information and leading the light to the second light-receiving part.
The biological information detector of claim 1, wherein
a relation S2 < S1 is satisfied, where S1 is an area of a reflecting surface of the first reflecting part, and S2 is an area of a reflecting surface of the second reflecting part.
the light-emitting part further emits a second light toward a different direction from the detection site;
the first sensor unit further has a third reflector for reflecting the second light and leading the light to the detection site; and
the first light-receiving part receives the light including the biological information obtained from the second light being reflected by the detection site.
The biological information detector in claim 1, wherein
the second sensor unit further has a fourth reflector for reflecting a part of the light including the second noise information and suppressing the light including the second noise information from reaching the second light-receiving part.
the first sensor unit further has
the second sensor unit further has
a relation Δhc > Δh is satisfied, where Δh is a distance between a light-receiving surface of the first light-receiving part and a center of an arc defining the spherical surface of the first reflecting part or a focus of a parabola defining the parabolic surface of the first reflecting part, and Δhc is a distance between a light-receiving surface of the second light-receiving part and a center of an arc defining the spherical surface of the second reflecting part or a focus of a parabola defining the parabolic surface of the second reflecting part.
A biological information measurement device comprising
the biological information detector described in claim 1; and
The biological information measurement device in claim 7, wherein
EP20100197367 2010-01-05 2010-12-30 Biological information detector and biological information measurement device Withdrawn EP2340764A1 (en)
JP2010000451A JP5454147B2 (en) 2010-01-05 2010-01-05 Biological information detector and biological information measuring device
EP2340764A1 true EP2340764A1 (en) 2011-07-06
EP20100197367 Withdrawn EP2340764A1 (en) 2010-01-05 2010-12-30 Biological information detector and biological information measurement device
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