Apparatus for measuring a blood parameter
First Claim
1. An apparatus for measuring a blood parameter comprising:
- at least first and second light sources for emitting light having first and second light intensities, respectively, toward a blood-receiving location, the light emitted by said first and second light sources having first and second wavelength characteristics, respectively, said first and second wavelength characteristics being different;
a detector for receiving light from the first and second light sources after interaction with blood at the blood-receiving location;
means for adjusting the intensity of the light emitted by the first light source so that intensity of the light at the detector from the first light source is substantially constant over a range of values of the blood parameter and for adjusting the intensity of the light emitted by the second light source so that intensity of light at the detector from the second light source is substantially constant over a range of values of the blood parameter; and
means for providing a signal which is related to the intensity of at least one of the first and second light sources and which provides an indication of the blood parameter.
2 Assignments
0 Petitions
Accused Products
Abstract
An apparatus for measuring a blood parameter comprising a red light source and an infrared light source for directing light toward a blood-receiving location and a detector, for receiving light from the first and second light sources which has been back scattered by the blood. The intensity of the first light source is adjusted so that the intensity of light at the detector from the first light source remains substantially constant over a range of values of the blood parameter and the intensity of the second light source is adjusted so that the intensity of light at the detector from the second light source is substantially constant over a range of values of the blood parameter. A signal is provided which is related to the intensity of one or both of the light sources and which provides an indication of the blood parameter. A circuit is provided to compensate for errors resulting from the light sources.
-
Citations
17 Claims
-
1. An apparatus for measuring a blood parameter comprising:
-
at least first and second light sources for emitting light having first and second light intensities, respectively, toward a blood-receiving location, the light emitted by said first and second light sources having first and second wavelength characteristics, respectively, said first and second wavelength characteristics being different; a detector for receiving light from the first and second light sources after interaction with blood at the blood-receiving location; means for adjusting the intensity of the light emitted by the first light source so that intensity of the light at the detector from the first light source is substantially constant over a range of values of the blood parameter and for adjusting the intensity of the light emitted by the second light source so that intensity of light at the detector from the second light source is substantially constant over a range of values of the blood parameter; and means for providing a signal which is related to the intensity of at least one of the first and second light sources and which provides an indication of the blood parameter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. An apparatus for measuring a blood parameter comprising:
-
a light source for emitting light having an intensity toward a blood-receiving location; a detector for receiving light from the light source after the emitted light interacts with the blood at the blood-receiving location; a feedback loop responsive to intensity of the light received by the detector for providing a feedback signal for adjusting the intensity of the light source so that the intensity of the light received by the detector from the light source is substantially constant over a range of values of the blood parameter; said emitted light intensity varying with the feedback signal in accordance with a predetermined relationship and being subject to deviating from said relationship; a reference detector for receiving at least some of the light emitted by the light source and providing a reference detector signal which is related to the intensity of the light it receives; means responsive to the feedback signal and the reference detector signal for providing a drive signal for energizing the light source to make the emitted light intensity more in accordance with said relationship; and means responsive to the feedback signal for providing an output signal which provides an indication of the blood parameter. - View Dependent Claims (12, 13, 14, 15)
-
-
16. An apparatus for measuring a blood parameter comprising:
-
at least first and second light sources for emitting light having first and second light intensities, respectively, toward a blood-receiving location, the light emitted by the first and second light sources having first and second wavelength characteristics, respectively, said first and second wavelength characteristics being different; a detector for receiving light from the first and second light sources after interaction with blood at the blood-receiving location; a feedback loop for adjusting the intensity of the light emitted by the first light source so that intensity of the light at the detector from the first light source is substantially constant over a range of values of the blood parameter and for adjusting the intensity of the light emitted by the second light source so that intensity of light at the detector from the second light source is substantially constant over a range of values of the blood parameter; and a signal processor for providing a signal which is related to the intensity of at least one of the first and second light sources and which provides an indication of the blood parameter.
-
-
17. An apparatus for measuring a blood parameter comprising:
-
a light source for emitting light having an intensity toward a blood-receiving location; a detector for receiving light from the light source after the emitted light interacts with the blood at the blood-receiving location; a feedback loop responsive to intensity of the light received by the detector for providing a feedback signal for adjusting the intensity of the light source so that the intensity of the light received by the detector from the light source is substantially constant over a range of values of the blood parameter; said emitted light intensity varying with the feedback signal in accordance with a predetermined relationship and being subject to deviating from said relationship; a reference detector for receiving at least some of the light emitted by the light source and providing a reference detector signal which is related to the intensity of the light it receives; a signal correction network responsive to the feedback signal and the reference detector signal for providing a drive signal for energizing the light source to make the emitted light intensity more in accordance with said relationship; and a signal processor responsive to the feedback signal for providing an output signal which provides an indication of the blood parameter.
-
Specification