U.S. patent application number 13/755432 was filed with the patent office on 2013-08-08 for physiological sensor.
This patent application is currently assigned to Covidien IP. The applicant listed for this patent is Covidien LP. Invention is credited to BRUCE J. BARRETT, Oleg Gonopolskiy, Rick Scheuing, Ronald A. Widman.
Application Number | 20130204141 13/755432 |
Document ID | / |
Family ID | 40622059 |
Filed Date | 2013-08-08 |
United States Patent
Application |
20130204141 |
Kind Code |
A1 |
BARRETT; BRUCE J. ; et
al. |
August 8, 2013 |
PHYSIOLOGICAL SENSOR
Abstract
A sensor used to measure physiological characteristics of body
tissues is provided. The physiological sensor includes a first
light source assembly having a first light source in parallel with
a second light source. Each of the first light source and the
second light source have an anode and a cathode. A second light
source assembly includes a third light source in parallel with a
fourth light source. Each of the third light source and the fourth
light source have an anode and a cathode. The anode of the first
light source is electrically connected to the cathode of the second
light source, the anode of said third light source, and the cathode
of said fourth light source. The anode of the third light source is
electrically connected to the cathode of the fourth light
source.
Inventors: |
BARRETT; BRUCE J.;
(Birmingham, MI) ; Gonopolskiy; Oleg; (West
Bloomfield, MI) ; Widman; Ronald A.; (Macomb, MI)
; Scheuing; Rick; (Rochester Hills, MI) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Covidien LP; |
Boulder |
CO |
US |
|
|
Assignee: |
Covidien IP
Boulder
CO
|
Family ID: |
40622059 |
Appl. No.: |
13/755432 |
Filed: |
January 31, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
11963174 |
Dec 21, 2007 |
8380272 |
|
|
13755432 |
|
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Current U.S.
Class: |
600/476 |
Current CPC
Class: |
A61B 5/6814 20130101;
A61B 2562/046 20130101; A61B 5/0059 20130101; A61B 5/14553
20130101; A61B 2562/0233 20130101; A61B 2562/0242 20130101; A61B
5/02427 20130101 |
Class at
Publication: |
600/476 |
International
Class: |
A61B 5/00 20060101
A61B005/00 |
Claims
1-13. (canceled)
14. A sensor comprising: a first light source assembly including a
first light source and a second light source, each of said first
light source and said second light source having an anode and a
cathode; a second light source assembly including a third light
source and a fourth light source, each of said third light source
and said fourth light source having an anode and a cathode; and
wherein said anode of said first light source is electrically
connected to each of said cathode of said second light source, said
anode of said third light source, and said cathode of said fourth
light source and wherein said anode of said third light source is
electrically connected to said cathode of said fourth light
source.
15. The sensor of claim 16, wherein said cathode of said first
light source is electrically connected to said anode of said second
light source and said cathode of said second light source is
electrically connected to said cathode of said fourth light
source.
16. The sensor of claim 14, further comprising a third light source
assembly including a fifth light source and a sixth light source
and each of said fifth light source and said sixth light source
having an anode and a cathode, and wherein said anode of said fifth
light source is electrically connected to said cathode of said
first light source, said anode of said second light source, and
said cathode of said sixth light source.
17. The sensor of claim 16, wherein said cathode of said fifth
light source is electrically connected to said cathode of said
third light source, said anode of said fourth light source, and
said anode of said sixth light source.
18. The sensor of claim 16, wherein said anode of said sixth light
source is electrically connected to said cathode of said third
light source and said anode of said fourth light source, and said
cathode of said sixth light source is electrically connected to
said cathode of said first light source and said anode of said
second light source.
19. The sensor of claim 14, further comprising a light detector in
optical communication with said first light source assembly and
said second light source assembly.
20. The sensor of claim 14, further comprising a pad defining at
least one opening and wherein at least one of said first light
source assembly and said second light source assembly is disposed
in said at least one opening.
21. The sensor of claim 14, wherein at least one of said first
light source assembly and said second light source assembly
includes at least one of a light emitting diode and a laser
diode.
22. A sensor comprising: a first light source assembly having two
light sources arranged in a first anti-parallel pair; and a second
light source assembly having two light sources arranged in a second
anti-parallel pair; wherein one light source from the first light
source assembly is arranged in parallel with one light source from
the second light source assembly.
23. The sensor of claim 22, further comprising a third light source
assembly having two light sources arranged in a third anti-parallel
pair, wherein one light source from the first light source assembly
and one light source from the second light source assembly are
arranged in parallel with one light source from the third light
source assembly.
24. The sensor of claim 22, further comprising a light detector in
optical communication with the first light source assembly and the
second light source assembly.
25. The sensor of claim 22, further comprising a pad defining at
least one opening and wherein at least one of the first light
source assembly and the second light source assembly is disposed in
the at least one opening.
26. The sensor of claim 22, wherein at least one of the first light
source assembly and the second light source assembly includes at
least one of a light emitting diode and a laser diode.
27. The sensor of claim 22, wherein the first light source assembly
and the second light source assembly are electrically connected to
a monitoring device, wherein a number of wires connecting the first
and second light source assemblies to the monitoring device is less
than a total number of light sources in the first and second light
source assemblies.
28. A physiological sensor system comprising: a sensor having a
first light source assembly having two light sources arranged in a
first anti-parallel pair and a second light source assembly having
two light sources arranged in a second anti-parallel pair, wherein
one light source from the first light source assembly is arranged
in parallel with one light source from the second light source
assembly; and a monitoring device electrically connected to the
sensor, wherein a number of wires connecting the sensor to the
monitoring device is less than a total number of light sources in
the first and second light source assemblies.
29. The physiological sensor system of claim 28, wherein a maximum
number of light source assemblies disposed on the sensor is defined
by the following equation: N.sub.LSA=N.sub.W*(N.sub.W-1)/2, wherein
N.sub.LSA is the number of light source assemblies and N.sub.w is
the number of wires connecting the sensor to the monitoring
device.
30. The physiological sensor system of claim 28, wherein the
monitoring device includes plurality of switches arranged in pairs
and wherein no more than one switch in each pair is enabled at any
time.
31. The physiological sensor system of claim 30, wherein enabling
select combinations of the plurality of switches activates more one
light source from each of the first and second light source
assemblies.
32. The physiological sensor system of claim 30, wherein enabling
each of the plurality of switches in a predetermined sequence
activates each of the light sources in the first and second light
source assemblies according to the predetermined sequence.
33. The physiological sensor system of claim 28, wherein the sensor
includes a light detector in optical communication with the first
light source assembly and the second light source assembly.
Description
BACKGROUND
[0001] Physiological sensor systems, such as pulse, tissue and
cerebral oximeters, are used to measure a variety of physiological
characteristics in body tissues using two wavelengths of light. The
system generally includes a monitoring system connected to a sensor
pad that adheres to the portion of the body being tested. The
sensor pad includes a plurality of light sources in optical
communication with at least one light detector. The light sources
are activated by applying an excitation current source to an
electrical wire connected to each light source. When activated, the
light sources transmit light at specific wavelengths through the
body tissue to the optical detector. The amount of light received
by the light detector after attenuation by the body tissue is
indicative of the physiological characteristic being tested.
[0002] To improve the accuracy of the measurement, or to enable the
measurement of additional physiological characteristics, additional
wavelengths of light can be used. This generally necessitates the
addition of light sources requiring additional wires to carry the
excitation potentials. Unfortunately, the addition of wires adds to
the cost and complexity of the system. Moreover, monitoring systems
are generally configured to work with sensor pads having a fixed
number of wires. For example, if a monitoring system is configured
to work with sensor pads having a three wire configuration, a
sensor pad using additional light sources and having any more than
three wires may not be compatible with the existing monitoring
system.
[0003] One known method used to minimize the number of wires in a
sensor pad when increasing the number of light sources includes
having multiple light sources connected in a matrix of rows and
columns of wires. The light sources in this configuration are
activated by sequentially addressing the row and column of each
light source with an excitation path. In this way, four wires
provide connection and activation of four light sources. If pairs
of light sources are connected in parallel, the same configuration
of four wires can be used to connect and activate up to eight light
sources. This configuration, however, requires a minimum of four
wires and is limited to a maximum of eight light sources.
[0004] Accordingly, the embodiments described hereinafter were
developed in light of these and other drawbacks associated with
increasing the number of light sources in a physiological sensor
without increasing the number of wires.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] FIG. 1 is a perspective view of an exemplary physiological
sensor according to an embodiment;
[0006] FIG. 2 is a bottom view of a pad of the physiological
sensor, according to an embodiment;
[0007] FIG. 3 is a bottom view of the physiological sensor
according to another embodiment with multiple light source
locations;
[0008] FIG. 4 is a bottom view of the physiological sensor
according to third embodiment with multiple light source
locations;
[0009] FIG. 5 is a bottom view of a physiological sensor having a
plurality of sensing pads;
[0010] FIG. 6 is a block diagram illustrating an exemplary control
scheme, according to an embodiment;
[0011] FIG. 7 is a diagram illustrating an exemplary control
circuit and light assembly, according to an embodiment;
[0012] FIG. 8 is a diagram illustrating another exemplary control
circuit and light assembly, according to an embodiment;
[0013] FIG. 9 is a diagram illustrating another exemplary control
circuit and light assembly, according to an embodiment;
[0014] FIG. 10 is a diagram illustrating the exemplary control
circuit and light assembly as set forth in FIG. 9 having multiple
current sources; and
[0015] FIG. 11 is a diagram illustrating another exemplary control
circuit and light assembly, according to an embodiment.
DETAILED DESCRIPTION
[0016] A physiological sensor that allows for an increased number
of light sources without an increase in the number of wires is
provided. Specifically, the physiological sensor can use four or
six light sources in a three-wire configuration, or alternatively,
up to twelve light sources in a four-wire configuration. In either
embodiment, the physiological sensor includes one or more light
source assemblies electrically connected to a monitoring system and
in optical communication with at least one light detector. Each
light source assembly includes at least one light source.
[0017] The arrangement of the light sources allows the
physiological sensor to measure physiological characteristics of
body tissue such as oxygen saturation or other various hemoglobin
species with increased accuracy and without a significant increase
in size or cost. The arrangement of the light sources may also
measure concentrations of additional chromospheres in tissue
besides hemoglobin. The spatial relationship of the light sources
relative to the light detector may enhance spatial resolution and
provide values at different depths, which may help in organ oxygen
delivery monitoring.
[0018] Moreover, because the physiological sensor maintains a three
or four wire configuration, the physiological sensor may be used
with pre-existing monitoring systems, thus making the physiological
sensor described herein backwards compatible. It is to be
understood that the physiological sensor may be configured to work
with any number of wires since the number of light assemblies (each
having two light sources) is related to the number of wires.
Specifically, the number of light source assemblies can be
calculated by the equation: N.sub.LSA=N.sub.W*(N.sub.W-1)/2,
wherein N.sub.LSA is the number of light source assemblies and
N.sub.W is the number of wires.
[0019] FIG. 1 illustrates an exemplary physiological sensor system
10 that includes a monitoring system 12 connected to a sensor pad
14 through a cable 16. As best shown in FIG. 2, the sensor pad 14
includes a plurality of light sources 18 in optical communication
with first and second light detectors 20, 22. It is to be
appreciated that multiple light sources 18 may be disposed in
multiple openings of the sensor pad 14. The plurality of light
sources 18 may include any light source known in the art, including
but not limited to, light emitting diodes, laser diodes or any
combination thereof. Typically, the frequency of the light
excitation and wavelength of the light source is dependent upon the
application. For instance, in cerebral oximetry, pulse oximetry, or
tissue oximetry applications, the light sources 18 may have a
wavelength in the visible and/or infrared spectrum. For instance,
the light sources 18 may have a wavelength between 600 nm and 1000
nm, including, but not limited to, a wavelength of 660 nm, 724 nm,
750 nm, 770 nm, 812 nm, 850 nm, 905 nm, or any combination thereof.
It is to be understood that the light sources 18 may have other
wavelengths to measure other physiological characteristics.
[0020] As shown in FIGS. 3 and 4, the plurality of light sources 18
may be mounted in two or more different physical locations on the
sensor pad 14 or in openings in the pad 14. By adding additional
light source assemblies when the physiological sensor system 10 is
used as a cerebral oximeter sensor, the monitoring system 12 can
obtain additional absorption spectra at additional wavelengths. The
additional absorption spectra can help to better define the
extinction curves for various blood and tissue chromophores,
allowing more accurate determination of their relative
concentrations. In one embodiment, each light source 18 is
illuminated sequentially and independently, allowing measurement of
light absorption at specific wavelengths by one or more of the
light detectors 20, 22. Alternatively, two or more light sources 18
may be illuminated simultaneously to provide additional light
output and an improved signal-to-noise ratio at specific
wavelengths. This may be necessary because certain wavelengths of
light do not penetrate as deeply into tissue as other wavelengths
do. As will be discussed in greater detail below, illuminating
several light sources 18 simultaneously may include multiple
current sources. Alternatively, certain light sources may not have
the same light output as others. Simultaneously illuminating two or
more of these lower output light sources can increase the effective
light output, improving signal-to-noise ratio and stability.
[0021] In another embodiment, the physiological sensor system 10
may be used for fractional oximetry to measure fractional oxygen
saturation and additional hemoglobin species in deep tissue of the
brain, other organs, skin, or in skeletal muscle tissue. By
selecting wavelengths of light appropriately, additional fractional
concentrations of other hemoglobin species such as
carboxyhemoglobin and methemoglobin can be determined. Most
noninvasive oximeters measure functional hemoglobin oxygen
saturation, which is defined as the ratio of oxyhemoglobin to the
unbound hemoglobin that is available for oxygen binding. As such,
it does not measure or take into effect the proportion of
hemoglobin that is bound to other compounds such as carbon monoxide
(carboxyhemoglobin) or hydrogen sulfide (sulfhemoglobin).
Additional species of hemoglobin such as methemoglobin, where the
ferrous iron has been oxidized to ferric iron, are not measured
either. By incorporating additional wavelengths of light, the
effect of additional chromophores with unique extinction curves can
be measured, enabling estimation of the fraction of each hemoglobin
compound, or fractional saturation.
[0022] In yet another embodiment, some of the plurality of light
sources 18 may be used for cerebral or tissue oximetry and others
of the plurality of light sources 18 may be used for pulse oximetry
to measure arterial blood hemoglobin oxygen saturation. This allows
the physiological sensor system 10 to measure various physiological
characteristics with the same sensor pad 14. In this embodiment, a
first light source assembly 44 may use selected wavelengths of
light and be located a sufficient distance from one of the
detectors 20, 22 to measure cerebral oxygen saturation while a
second light source assembly 46 may use wavelengths suited for
measurement of arterial oxygen saturation using reflectance pulse
oximetry and would therefore be located close to another of the
light detectors 20, 22. Alternatively, the first light detector 20
may be used to measure arterial oxygen saturation based on the
spatial relationship of the plurality of light sources 18. This
embodiment also allows arterial saturation of deeper tissues to be
measured because the depth of penetration of photons is
proportional to the separation distance between the light source 18
and the light detector 20, 22.
[0023] In yet another embodiment, the plurality of light sources 18
can be spatially arranged to increase the accuracy of the
measurements. For instance, the first light source assembly 44 can
have different wavelengths that penetrate less deeply into the body
tissue than other light source assemblies. For instance, as shown
in FIG. 3, placing the first light source assembly 44 closer to the
light detector 20 and slightly offset from the first light source
assembly 46 allows the first light source assembly 44 to penetrate
into the body tissue shallower than the second light source
assembly 46. Likewise, placing the second light source 46 further
away from the light detector 20 and slightly offset from the first
light source assembly 44 causes light generated by the second light
source assembly 46 to penetrate deeper into the body tissue.
Alternatively, as shown in FIG. 4, the first light source assembly
44 may be spaced away from the second light source assembly 46 and
more offset from the second light source assembly 46 to achieve a
similar result. In this embodiment, the ratios of the signals from
each of the light detectors 20, 22 can be computed using both light
source assemblies 44, 46.
[0024] In yet another embodiment, the physiological sensor system
10 may contain a plurality of sensor pads 14 and each sensor pad 14
may contain at least one light source assembly 44 and one light
detector 20. This arrangement of the physiological sensor system 10
may be used to measure two physiological parameters including, but
not limited to, cerebral blood saturation and arterial blood
saturation. The cerebral measurement may require a low skin
perfusion site on the forehead to reduce interference from
extra-cranial signals. However, arterial blood oxygen saturation
may require high skin perfusion. Thus, in one embodiment, for
cerebral oximetry, the sensor pad 14 may be placed on the forehead
directly below the hair line. On the other hand, for pulse
oximetry, the sensor pad 14 may be placed on the forehead directly
above the eyes. In this embodiment, a single sensor pad 14 may be
inconvenient to use at least for an adult patient. Therefore, two
sensor pads 14 may be used.
[0025] Referring now to FIG. 5, in one exemplary approach, the
physiological sensor system 10 includes a first sensor pad 14A and
a second sensor pad 14B. The first sensor pad 14A may be used, for
instance, for tissue oximetry, and the second sensor pad 14B may be
used, for instance, for pulse oximetry. The first sensor pad 14A
may include the light source assemblies 44, 46, in optical
communication with the first and second light detectors 20, 22. It
is to be appreciated that the first sensor pad 14A may include any
number of light source assemblies 44, 46 and any number of light
detectors 20, 22. Likewise, the second sensor pad 14B may include
the light source assemblies 44, 46, in optical communication with
the first and second light detectors 20, 22. It is to be
appreciated that the second sensor pad 14B may include any number
of light source assemblies 44, 46 and any number of light detectors
20, 22.
[0026] Other cases where two or more sensor pads 14 may be used
include measuring cerebral oxygenation from at least two sites of
the brain, or measuring cerebral and tissue oxygenation
simultaneously in infants. In this embodiment, the physiological
sensor system 10 may include at least two sensor pads 14, each
having at least two light detectors 20, 22 and at least two light
source assemblies 42, 46. The light source assemblies 42, 46 may be
connected as described above and excited sequentially in time.
[0027] As shown in FIG. 6, monitoring system 12 includes a control
circuit 24 and a processor 26 in communication with the plurality
of light sources 18 and light detectors 20, 22. The processor 26 is
configured to receive signals from light detectors 20, 22 and
converts the signals into data that indicates the physiological
characteristics of the body tissue. Furthermore, the processor 26
controls the control circuit 24 as will be discussed in greater
detail below. It is to be understood that the control circuit 24
may alternatively be controlled by a dedicated processor (not
shown) other than the processor 26 shown in FIG. 6. The monitoring
system 12 may output the data to a display 27 as shown in FIG.
1.
[0028] FIG. 7 illustrates an exemplary control circuit 24, which
includes at least one high switch 28 and at least one low switch
30. As discussed in greater detail below, it is to be understood
that the high switch 28 connects the light sources 18 to a higher
potential than the low switch 30. The high switch 28 and the low
switch 30 may be any switch known in the art, and even the same
type of switch. For instance, the high switch 28 and the low switch
30 may be transistors. In one embodiment, the high switch 28 may be
a PMOS type transistor and the low switch 30 may be an NMOS type
transistor. The high switch 28 and the low switch 30 may be
connected in an H-Bridge configuration.
[0029] The at least one high switch 28 and the at least one low
switch 30 are controlled by the processor 26 in the monitoring
system 12. In other words, the processor 26 opens and closes the at
least one high switch 28 and the at least one low switch 30 of the
control circuit 24 to activate a select combination of the
plurality of light sources 18. The monitoring system 12 includes a
voltage source 32 electrically connected to the control circuit 24
for providing voltage to the control circuit 24 and the plurality
of light sources 18. In addition, the monitoring system 12 may
further include a current source 34 that causes current to flow
from the voltage source 32 to ground 36. The low switches 30
connect each of the plurality of light sources 18 to the current
source 34. The current source 34 is connected to the ground 36 at a
ground potential. It is to be understood that the low switches 30
may connect to the plurality of light sources 18 directly to the
ground potential. Otherwise, in at least one embodiment, there is
no structural or functional difference between the high switches 28
and the low switches 30.
[0030] The control circuit 24 may include any number of high
switches 28 or low switches 30. For instance, as shown in FIG. 7,
the control circuit 24 includes a first high switch HI1 in series
with a first low switch L1, the combination of which defines a
first switch pair 38. Likewise, the control circuit 24 includes a
second high switch HI2 in series with a second low switch L2, the
combination of which defines a second switch pair 40. It is to be
understood that the control circuit 24 may include any number of
high switches 28 and low switches 30 to define any number of switch
pairs. For instance, referring to FIG. 8, the control circuit 24
may include a third high switch HI3 and a third low switch L3 in
series with the third high switch 1413 to define a third switch
pair 42. As shown in FIG. 8, the first switch pair 38 is in
parallel with the second switch pair 40 and the third switch pair
42.
[0031] Each high switch 28 and each low switch 30 have an anode and
a cathode. The anode of the high switch 28 directly or indirectly
connects to the voltage source 32 and the cathode of the low switch
30 directly or indirectly connects to a lower potential (i.e., a
ground potential 36 or the current source 34). When the control
circuit 24 includes multiple high switches 28, the anodes of each
of the high switches 28 are electrically connected to one another.
For example, referring to FIG. 7, the anode of the first high
switch HI1 may be electrically connected to the anode of the second
high switch HI2. Similarly, when the control circuit 24 includes
multiple low switches 30, the cathodes of each of the low switches
30 may be electrically connected. Again referring to FIG. 7, the
cathode of the first low switch L1 is electrically connected to the
cathode of the second low switch L2.
[0032] In operation, the processor 26 closes one of the high
switches 28 and one of the low switches 30 to activate one of the
plurality of light sources 18. In one embodiment, each light source
is connected to two switch pairs. The light source is powered by
the voltage source 32 when the high switch 28 in one of the switch
pairs is closed and the low switch 30 in another switch pair is
closed, completing an electrical circuit. It is to be understood
that multiple light sources may be illuminated by closing more than
one high switch 28 and/or more than one low switch 30. However,
closing the high switch 28 and the low switch 30 in the same switch
pair will cause an electrical short, and the light source will not
illuminate. In other words, the light source does not operate when
the high switch 28 and the low switch 30 from the same switch pair
are both closed. To prevent an electrical short, the processor 26
opens the low switch 30 in the switch pair when the high switch 28
in the switch pair is closed. Therefore, the light source is
electrically connected to the high switch 28 in one switch pair and
the low switch 30 in another switch pair. It is to be understood
that both the high switch 28 and the low switch 30 may be open at
the same time.
[0033] As shown in FIG. 7, the physiological sensor 10 includes a
first light source assembly 44 that is defined by at least one of
the plurality of light sources 18 and electrically connected to the
control circuit 24. As shown, the first light source assembly 44
includes a first light source LS1 in parallel with a second light
source LS2. As previously discussed, the first light source LS1 and
the second light source LS2 may be light emitting diodes or laser
diodes. Each of the first light source LS1 and the second light
source LS2 have an anode and a cathode. The anode of the first
light source LS 1 is electrically connected to the cathode of the
second light source LS2. In addition, the cathode of the first
light source LS1 is electrically connected to the anode of the
second light source LS2. Therefore, although disposed in parallel
with the second light source LS2, the first light source LS1 has an
opposite polarity to the second light source LS2. The first light
source LS1 and the second light source LS2 are each electrically
connected to at least two switch pairs. Specifically, the first
light source LS1 is electrically connected to the first high switch
HI1 and the second low switch L2, and the second light source LS2
is electrically connected to the second high switch HI2 and the
first low switch L1. The first high switch HI1 is in series with
the second low switch L2 when the first high switch HI1 and the
second low switch L2 are closed.
[0034] Likewise, the second high switch HI2 is in series with the
first low switch L1 when the second high switch HI2 and the first
low switch L1 are closed. In this embodiment, only one of the
plurality of light sources 28 may be illuminated at any time since
only one of the first high switch HI1 and the second high switch
HI2 may be closed because closing both the first high switch HI1
and the first low switch L1 or the second high switch HI2 and the
second low switch L2 would cause an electrical short. Therefore,
the processor 26 opens the first low switch L1 when the first high
switch RH is closed. Likewise, the processor 26 opens the second
low switch L2 when the second high switch HI2 is closed.
[0035] It is to be understood that the physiological sensor system
10 may include any number of light source assemblies. For instance,
referring to FIG. 8, the system 10 further includes a second light
source assembly 46 defined by at least one of the plurality of
light sources 18 and electrically connected to the monitoring
system 12. The second light source assembly 46 includes a third
light source LS3 in parallel with a fourth light source LS4.
Although disposed in parallel with the fourth light source LS4, the
third light source LS3 has an opposite polarity than the fourth
light source LS4. Each of the third light source LS3 and the fourth
light source LS4 have an anode and a cathode. The anode of the
third light source LS3 is electrically connected to the cathode of
the fourth light source LS4. The cathode of the third light source
LS3 is electrically connected to the anode of the fourth light
source LS4. In one embodiment, as shown in FIG. 8, the anode of the
third light source LS3 is also electrically connected to the anode
of the first light source LS1 and the cathode of the second light
source LS2. As in the previous embodiment, the first light source
LS1 is electrically connected to the first high switch HI1 and the
second low switch L2 and the second light source LS2 is
electrically connected to the second high switch HI2 and the first
low switch L1. In this embodiment, the third light source LS3 is
electrically connected to the first high switch HI1 and the third
low switch L3. The fourth light source LS4 is electrically
connected to the third high switch HI3 and the first high switch
HIL Again, the third high switch HI3 is in series with the third
low switch L3 to make up the third switch pair 42.
[0036] In this embodiment, it is possible for the processor 26 to
illuminate more than one of the plurality of light sources 18
simultaneously. For instance, the processor 26 may close the first
high switch HU and the second low switch L2 to illuminate the first
light source LS 1. The processor 26 may then close the third low
switch L3 to illuminate the third light source LS3 since both the
first light source LS1 and the third light source LS3 receive power
from the voltage source 32 when the first high switch HI1 is
closed. It is to be appreciated that the processor 26 may close the
third low switch L3 at the same time as closing the second low
switch L2 to illuminate the third light source LS3 simultaneously
with the first light source LS1, or the processor 26 may close the
third low switch L3 after closing the second low switch L2 to
illuminate the third light source LS3 sequentially with the first
light source LS 1. Alternatively, the processor 26 may close the
second high switch HI2 and the first low switch L1 to illuminate
the second light source LS2, and by closing the third high switch
HI3 while the second high switch HI2 and the first low switch L1
are closed, the processor 26 additionally illuminates the fourth
light source LS4. Therefore, in this embodiment, the processor 26
may illuminate two of the plurality of light sources 18.
[0037] Referring now to FIG. 9, the physiological sensor system 10
further includes a third light source assembly 48 that includes a
fifth light source LS5 in parallel with a sixth light source LS6.
Although disposed in parallel with the sixth light source LS6, the
fifth light source LS5 has an opposite polarity than the sixth
light source LS6. Each of the fifth light source LS5 and the sixth
light source LS6 have an anode and a cathode. The anode of the
fifth light source LS5 is electrically connected to the cathode of
the first light source LS1, the anode of the second light source
LS2, and the cathode of the sixth light source LS6. The cathode of
the fifth light source LS5 is electrically connected to the cathode
of the third light source LS3, the anode of the fourth light source
LS4, and the anode of the sixth light source LS6. The anode of the
sixth light source LS6 is electrically connected to the cathode of
the third light source LS3 and the anode of the fourth light source
LS4. The cathode of the sixth light source LS6 is electrically
connected to the cathode of the first light source LS1 and the
anode of the second light source LS2. As in the previous
embodiment, the processor 26 may illuminate more than one of the
plurality of light sources 18 simultaneously. For instance, the
processor 26 may close the first high switch HI1 and the second low
switch L2 to illuminate the first light source LS1. At the same
time, the processor 26 may close the third low switch L3 to
illuminate the third light source LS3. Therefore, the processor 26
may illuminate more than one of the plurality of light sources 18
simultaneously.
[0038] In one exemplary embodiment, to illuminate more than one of
the plurality of light sources 18 simultaneously, the physiological
sensor system 10 may include more than one current sources 34.
Referring now to FIG. 10, the physiological sensor 10 includes a
first current source 34A electrically connected to the first low
switch L1, a second current source 34B electrically connected to
the second low switch L2, and a third current source 34C
electrically connected to the third low switch L3. The current
sources 34A, 34B, and 34C help to ensure that the light sources 18
maintain a minimum amount of brightness when the light sources 18
are simultaneously illuminated.
[0039] Again, it is to be understood that the physiological sensor
system 10 may include any number of light source assemblies. For
instance, referring to FIG. 11, the physiological sensor system 10
further includes a fourth light source assembly 50, a fifth light
source assembly 54, and a sixth light source assembly 56. In
addition, the control circuit 24 includes a fourth switch pair 52
having a fourth high switch HI4 in series with a fourth low switch
L4. The fourth light source assembly 50 includes a seventh light
source LS7 in parallel with an eighth light source LS8. The seventh
light source LS7 and the eighth light source LS8 each have an anode
and a cathode. The anode of the seventh light source LS7 is
electrically connected to the fourth high switch HI4 and the
cathode of the seventh light source LS7 is electrically connected
to the third ground 36 source. The anode of the eighth light source
LS8 is electrically connected to the third high switch HI3 and the
cathode of the eighth light source LS8 is electrically connected to
the fourth low switch L4. The fifth light source assembly 54
includes a ninth light source LS9 in parallel with a tenth light
source LS10. The ninth light source LS9 and the tenth light source
LS10 each have an anode and a cathode. The anode of the ninth light
source LS9 is electrically connected to the fourth high switch HI4
and the cathode of the ninth light source LS9 is electrically
connected to the second low switch L2. The anode of the tenth light
source LS10 is electrically connected to the second high switch HI2
and the cathode of the tenth light source LS 10 is electrically
connected to the fourth low switch L4. The sixth light source
assembly 56 includes an eleventh light source LS11 in parallel with
a twelfth light source LS12. The eleventh light source LS11 and the
twelfth light source LS12 each have an anode and a cathode. The
anode of the eleventh light source LS11 is electrically connected
to the fourth high switch HI4 and the cathode of the eleventh light
source LS11 electrically connected to the first low switch L1. The
anode of the twelfth light source LS12 is electrically connected to
the first high switch HI1 and the cathode of the twelfth light
source LS12 is electrically connected to the fourth low switch L4.
As in the previous embodiments, the processor 26 may illuminate one
or more of the plurality of light sources 18. For instance, the
processor 26 may close the first high switch HIL the second low
switch L2, and the fourth low switch L4 to illuminate the first
light source LS1, the third light source LS3, and the twelfth light
source LS12. Alternatively, the processor 26 may close the first
high switch HIL the third high switch HI3, the fourth high switch
HI4, and the second low switch L2 to illuminate the first light
source LS1, the sixth light source LS6, and the ninth light source
LS9.
[0040] It is to be understood that the physiological sensor system
10 may include any number of light source assemblies, each
including any number of light sources 18. Also, the processor 26
may close different combinations of the high switches 28 and the
low switches 30 to illuminate alternative combinations of the
plurality of light sources 18.
[0041] It is to be understood that the above description is
intended to be illustrative and not restrictive. Many alternative
approaches or applications other than the examples provided would
be apparent to those of skill in the art upon reading the above
description. The scope of the invention should be determined, not
with reference to the above description, but should instead be
determined with reference to the appended claims, along with the
full scope of equivalents to which such claims are entitled. It is
anticipated and intended that future developments will occur in the
arts discussed herein, and that the disclosed systems and methods
will be incorporated into such future examples. In sum, it should
be understood that the invention is capable of modification and
variation and is limited only by the following claims.
[0042] The present embodiments have been particularly shown and
described, which are merely illustrative of the best modes. It
should be understood by those skilled in the art that various
alternatives to the embodiments described herein may be employed in
practicing the claims without departing from the spirit and scope
as defined in the following claims. It is intended that the
following claims define the scope of the invention and that the
method and apparatus within the scope of these claims and their
equivalents be covered thereby. This description should be
understood to include all novel and non-obvious combinations of
elements described herein, and claims may be presented in this or a
later application to any novel and non-obvious combination of these
elements. Moreover, the foregoing embodiments are illustrative, and
no single feature or element is essential to all possible
combinations that may be claimed in this or a later
application.
[0043] All terms used in the claims are intended to be given their
broadest reasonable constructions and their ordinary meanings as
understood by those skilled in the art unless an explicit
indication to the contrary is made herein. In particular, use of
the singular articles such as "a," "the," "said," etc. should be
read to recite one or more of the indicated elements unless a claim
recites an explicit limitation to the contrary.
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