Blood flow sensor and blood flow measurement device
Inventors
KANAUMI, Eiichi • OGINO, Hiroaki • Ogawa, Tomoyuki
Assignees
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Publication Number
US-11202581-B2
Publication Date
2021-12-21
Expiration Date
Abstract
To provide a blood flow sensor in which a fluctuation of measurement results is suppressed during measurement of the blood flow volume. A probe portion is provided with a sensor portion which has a laser diode generating laser light, a photodiode receiving light, and a sensor housing having a contact surface contacting a subject and which irradiates a subject with the laser light generated by the laser diode through the contact surface, receives reflected light from the subject in the photodiode, and outputs a signal relating to the received light amount, a holding portion holding the sensor housing so as to be movable in an up-and-down direction crossing the contact surface, and a coil spring absorbing and transmitting external force applied to the holding portion to the sensor portion.
Core Innovation
The invention relates to a blood flow sensor having an optical sensor portion that includes a laser element and a light receiving element. The laser element irradiates a subject with laser light through a contact surface of a housing, and the light receiving element receives reflected light and outputs a first signal relating to a received light amount. The housing is held by a holding portion that is movable relative to the housing in movement directions toward and away from the contact surface.
A first and a second non-electromagnetic elastic member within the holding portion bias the optical sensor portion so that a moving member can shift under an external force applied to the sensor. The moving member includes a first projection, a second projection, and a first section located between the non-electromagnetic elastic members, and a pressure sensor within the holding portion detects pressure from contact with the first projection when the moving member is moved in a second direction opposite a first direction.
In an equilibrium state with no external force acting on the elastic members, the first projection is spaced apart from the pressure sensor by a first distance and the second projection is spaced apart from the optical sensor portion by a second distance. In related configurations, sensor behavior is governed by first and second threshold values so that contact of the first projection with the pressure sensor and contact conditions involving the second projection relative to a seat of the optical sensor portion depend on the magnitude of the external force.
A blood flow volume measuring device uses the first and second signals to calculate blood flow volume, stores the first and second threshold values to issue a warning based on pressure sensor readings when the predetermined contact conditions indicate excessive load, and applies predetermined timings to perform or stop and delete pressure-based calculations before computing and displaying the blood flow measure based on retained calculation results.
Claims Coverage
The independent claim defines the movable housing and elastic-member biased contact mechanism with a pressure sensor and equilibrium-state spacing, while identifying how the first and second signals relate to received light and pressure-from-projection contact. Dependent claims add threshold-based contact behavior, quantify equilibrium distance relationships, and extend the concept to blood flow volume measurement with warning and timing-controlled pressure-based calculation processing.
Movable housing with non-electromagnetic elastic bias for projection-based pressure sensing
A blood flow sensor with an optical sensor portion including a laser element and a light receiving element, a housing having a contact surface, a holding portion movable relative to the housing, a first and a second non-electromagnetic elastic member within the holding portion, and a moving member biased by the first non-electromagnetic elastic member such that a pressure sensor outputs a second signal in response to pressure from contact with a first projection under an externally applied force.
Equilibrium spacing between the first projection and the pressure sensor, and between the second projection and the optical sensor portion
The blood flow sensor has an equilibrium state with no external force acting upon the first and second non-electromagnetic elastic members, where the first projection is spaced apart from the pressure sensor by a first distance and the second projection is spaced apart from the optical sensor portion by a second distance.
Threshold-governed projection contact with a pressure sensor and optical sensor seat
A blood flow sensor having a moving member with a first projection and a second projection, wherein external force is compared to first and second threshold values to determine whether the first projection contacts the pressure sensor and whether a seat of the optical sensor portion is in contact with the second projection depending on the external force level.
Quantified equilibrium distance relationship between projections and sensor components
A blood flow sensor configured such that, in an equilibrium state, a second distance is greater than a first distance.
Blood flow volume calculation with threshold storage and warning based on pressure conditions
A blood flow volume measuring device that calculates blood flow volume from the first signal and the second signal, stores first and second threshold values, and issues a warning based on pressure sensor readings based on pressure-related contact conditions of the first and second projections relative to the pressure sensor and a seat of the optical sensor portion.
Timing-controlled pressure-based calculation gating with display of blood flow measure
A blood flow volume measuring device that calculates a blood flow measure from first and second signals, stores and uses predetermined timings, performs or stops and deletes pressure-based calculations based on pressure and optical sensor projection contact conditions, and computes and displays the blood flow measure based on retained calculation results.
Across the independent and dependent claims, the invention provides an optical blood flow sensor with a movable housing mechanism biased by non-electromagnetic elastic members, a pressure sensor that outputs a pressure-related second signal when a first projection contacts it, equilibrium-state spacing between projections and sensors, and threshold-based contact behavior. The dependent claim set further links the pressure conditions to warning, and uses predetermined timings to control whether pressure-based calculations are performed, stopped, deleted, or retained before displaying the blood flow measure.
Stated Advantages
Suppresses low-reliability outputs by controlling whether blood-flow calculations are performed and whether results are averaged/displayed based on detected contact pressure conditions.
Issues a warning when excessive load is detected based on pressure exceeding a second threshold value.
Documented Applications
Blood flow volume measurement using an LDF blood flow sensor where blood flow volume is calculated from first and second signals and displayed based on retained calculation results under predetermined timing and contact conditions.
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