This application claims a priority from Japanese Patent Application No. 2010-200535, filed on Sep. 8, 2010, the entire contents of which are herein incorporated by reference.
1. Technical Field
The present invention relates to a biological information measuring apparatus, and in particular, to a biological information measuring apparatus using a confocal optical system.
2. Related Art
When a subject under test is irradiated with light from a light source by making use of near-infrared spectroscopy, and so forth, light absorption characteristics according to an amount of a component of the subject under test is indicated in a wavelength range unique to the component contained in the subject under test, and therefore, techniques have since been known whereby absorbance (light absorption capacity of a specific component) is worked out from measurement light such as reflected light from the subject under test, and so forth to thereby analyze components contained in the subject under test on the basis of a absorbance spectrum of the measurement light.
As a biological information measuring apparatus for measuring components of the internal tissues of a biological object {for example, various substances (concentration of a component such as a blood glucose value in blood, and so forth) contained in blood of a blood vessel of, for example, a human body. an animal, or in a tissue fluid of the tissues thereof}, in particular, there has been proposed a biological information measuring apparatus for measuring respective reflected light beams by measuring respective laser beams at not less than two wavelengths, outgoing from a wavelength tunable laser, and reflected by the internal tissues of a biological object as a subject under test, and light transmitted through a biological object with the use of the wavelength tunable laser, and a confocal optical system, as is the case with Patent Document 1, thereby measuring components of the internal tissues of the biological object.
More specifically, the respective laser beams at not less than two wavelengths are irradiated against the internal tissues of the biological object as the subject under test, components of the internal tissues of the biological object are worked out by conducting a well-known test after an absorbance spectrum is found from light reflected by the internal tissues of the biological object, and light transmitted through the biological object, and a formula for expressing correlation between the absorbance spectrum, and the components of the internal tissues of the biological object (hereinafter referred to as correlation formula) is prepared to be kept in memory in advance, and absorbance worked out from the reflected light from the internal tissues of the biological object, and the light transmitted through the biological object are substituted for those in the correlation formula, whereupon the components of the internal tissues of the biological object have been measured.
Further, the biological information measuring apparatus according to Patent Document 1 is provided with a transfer-drive mechanism capable of causing the confocal optical system, and the biological object to be relatively and three-dimensionally transferred. In Patent Document 1, there has been proposed the biological information measuring apparatus in which the focal position of the confocal optical system is relatively and three-dimensionally transferred against the biological object by relatively and three-dimensionally transferring the confocal optical system, and the biological object with the use of the transfer-drive mechanism, thereby acquiring three-dimensional data on the internal tissues of a biological object, and reliably identifying a site of the biological object, to be measured, whereupon components of the biological object, at the site, can be reliably and noninvasively measured.
In
The parallel rays having transmitted through the half mirror 3 is condensed by an objective lens 4 to be irradiated against the internal tissues of a biological object BL placed on a placement platform T. The laser beam reflected from the internal tissues of the biological object BL falls on the objective lens 4 again to be shaped into parallel rays, and the parallel rays are caused to fall on the half mirror 3, whereupon an optical path thereof is changed such that the parallel rays are reflected in a direction at an angle of approximately 90° against the optical axis of the objective lens 4.
The parallel rays whose optical path has been changed by the half mirror 3 to be thereby reflected are condensed into a laser beam by a lens 5, the laser beam falling on a pinhole 6. The laser beam having passed through the pinhole 6 is caused to fall on a photo detector 7 to be subsequently converted into an electric signal.
The photo detector 7 converts the laser beam into the electric signal whose intensity and magnitude will increase or decrease according to luminous energy of the laser beam as received, and the electric signal is delivered to an A/D converter 8. The A/D converter 8 converts the electric signal delivered from the photo detector 7 into digital data to be delivered to a data analyzer 9.
When respective laser beams at not less than two wavelengths differing from each other are irradiated against the biological object BL, the data analyzer 9 executes quantitative analysis of a component of the biological object BL on the basis of a plurality of electric signals as converted and outputted from the photo detector 7.
More specifically, in the case of quantifying a blood glucose value, that is, concentration of glucose in blood, since an analytical curve indicating correlation between the concentration of glucose in a measured blood, and absorbance of a laser beam is stored in the data analyzer 9 beforehand, the data analyzer 9 executes quantification of the concentration of glucose in the blood of the biological object BL on the basis of the analytical curve.
The following Patent document 1 is available as a related art literature related to the conventional biological information measuring apparatus described as above, and the following Patent document 2 is also available as a related art literature related to biological information on a measurement site of a finger.
With the conventional biological information measuring apparatus described as above, however, because the laser diode 1 in use as a light source of the confocal optical system is continuously driven, if continuous measurement is carries out for relatively long time, or output luminous energy of the laser diode 1 is increased in order to enhance an S/N ratio of a detection signal, this will cause an increase in temperature of a measurement site of the biological object BL, thereby raising the risk that a component as a measurement subject, at the measurement site, undergoes alteration in quality, or the measurement site is damaged.
Further, in the case of the conventional biological information measuring apparatus, with respect to the measurement site, no description other than “a biological object, such as an arm, and so forth, is placed on a placement platform” is given, and a specific measurement site, such as, for example, which part of the arm is appropriate, and so forth, is not identified.
Accordingly, there is a possibility that an appropriate and specific measurement site is not necessarily selected by measurement, and there is a risk that measurement results based on a common measurement condition cannot be obtained because the measurement site varies.
Further, it has been described that blood is collected from a subject under test to measure the concentration of glucose in the blood, and at the same time, the laser diode 1 is adjusted to acquire data on an analytical curve indigenous to the subject under test, whereupon a CPU carries out quantification of a biological component of the biological object BL on the basis of the analytical curve, however, how to identify the subject under test has not been described.
In this case, it is required that information necessary for identifying each subject under test is separately acquired prior to those measurements to be inputted, in order to preserve and manage data on an analytical curve and measurement data for every subject under test, and the subject under test must be checked at the time of each measurement that the subject under test is the person in question on the basis of specific information on each subject under test, so that a fairly heavy burden will be forced upon a measurement worker.
Further, most of the reflected light that has passed through the pinhole 6 of the confocal optical system to fall on the photo detector 7 is the reflected light at a position of the internal tissue, identified at a focal position F, while scattered light other than the reflected light is unable to pass through the pinhole 6 and is left as it is without being processed although scattered light contains biological information on the periphery of the measurement site of the biological object BL, so that it can be said that utilization efficiency of output light of the laser diode 1 is not necessarily high.
Exemplary embodiments of the present invention address the above disadvantages and other disadvantages not described above. However, the present invention is not required to overcome the disadvantages described above, and thus, an exemplary embodiment of the present invention may not overcome any disadvantages.
According to one or more illustrative aspects of the invention, there is provided a biological information measuring apparatus capable of automatically identifying a subject under test, and executing continuous measurement under a common measurement condition having selected a properly identified site at a high S/N ratio for relatively long hours as necessary, the biological information measuring apparatus being also capable of improving utilization efficiency of the output light of a laser.
According to one or more illustrative aspects of the invention, there is provided a biological information measuring apparatus using a confocal optical system provided with a laser serving as a light source thereof, and the biological information measuring apparatus comprises a laser drive means for effecting AC-driving so as to cause pulsed light to be outputted from the laser.
Embodiments of the invention are described hereinafter with reference to the accompanying drawings.
The laser diode 1 of the conventional confocal optical system has been driven in such a continuous light-emitting state as shown in
If the laser diode 1 is AC driven so as to be in the pulsed light-emitting states shown in
Thus, even if the laser diode 1 is AC driven so as to be in the pulsed light-emitting states shown in
The AC driving of the laser diode 1, according to the invention, can be applied to not only the biological information measuring apparatus configured as shown in
A biological information measuring apparatus shown in
In
The laser beam having transmitted through the half mirror 3 is condensed by an objective lens 4 to be used for irradiation of the internal tissues of the biological object BL. Those elements including the laser diode 1, the half mirror 3, and the objective lens 4 make up an irradiation system for irradiating the internal tissues of the biological object BL, the irradiation system being disposed such that the respective optical axes thereof are opposed to the biological object BL
The laser beam reflected by the internal tissues of the biological object BL is caused to fall on the half mirror 3 again via the objective lens 4, whereupon the laser beam has its optical path altered so as to be reflected in a direction substantially at 90° to the optical axis of the laser diode 1. The laser beam reflected by the half mirror 3, the optical path thereof having been altered, is caused to fall directly on a pinhole 6 without traveling through a lens. The laser beam having passed through the pinhole 6 is caused to fall on a photo detector 7 to be subsequently converted into an electric signal.
The photo detector 7 converts the laser beam into an electric signal that varies in intensity and magnitude in accordance with luminous energy of the laser beam as received, thereby inputting the electric signal to an A/D converter 8. The A/D converter 8 converts the electric signal delivered from the photo detector 7 into digital data to be delivered to a data analyzer 9. Those elements including the pinhole 6, and the photo detector 7 make up a light reception system, and the optical axis of the light reception system is disposed in a direction orthogonal to the optical axis of the irradiation system. Further, the laser diode 1, the objective lens 4, the pinhole 6, and the photo detector 7 make up a confocal optical system.
The data analyzer 9 executes quantitative analysis of components of the biological object BL on the basis of a plurality of the electric signals converted and outputted from the photo detector 7 when respective laser beams at not less than two different wavelengths are irradiated against the biological object BL.
With the adoption of such a configuration as described, the lens 2, and the lens 5, provided in the case of the conventional biological information measuring apparatus shown in
Further, the laser beam outputted from the laser diode 1 is condensed by the objective lens 4 without being shaped into parallel rays to be used for irradiation of a measurement site inside a biological object, so that it is possible to precisely fetch measurement data on a desired measurement site in the biological object BL.
With a configuration shown in
Further, in combination with movement of objective lens 4, a pinhole 6 may be moved along the direction of an optical axis B, and a photo detector 7 may be moved along the direction of an optical axis C.
With such a configuration as shown in
Further, with the biological information measuring apparatus shown in
With each of the biological information measuring apparatus described in the foregoing, if the laser diode 1 is driven by use of an automatic output control loop such that intensity of light from the laser diode 1, irradiated against a measurement target, is maintained at a predetermined value, stable measurement can be carried out.
By so doing, it is possible to inhibit variation in intensity of output light, attributable to temperature variation of the laser diode 1, and spatial intensity variation thereof, so that stable component-measurement results can be obtained.
Further, the output signal of the second photo detector 13 is added to a data analyzer 9 via an A/D converter 15, whereupon an output signal of a first photo detector 7 is divided by the output signal of the second photo detector 13, and the result is standardized, thereby enabling compensation for variation due to variation in the output of the laser diode 1, and variation due to reflection at the surface of the biological object BL as the measurement target.
The output signal of the third photo detector is also delivered to the data analyzer 9 via an A/D converter 16, whereupon the output signal of the first photo detector 7 is divided by the output signal of the third photo detector, and the result is standardized. As a result, the data analyzer 9 executes linear combination of two standardized signals to find combination coefficients by multivariate analysis, thereby compensating, with high precision, for the variation due to output variation of the laser diode 1, and the variation due to reflection at the surface of the biological object BL, on the basis of these values.
Further, the output signal of the fourth photo detector 17 is also delivered to the data analyzer 9 via an A/D converter 18, whereupon the output signal of the first photo detector 7 is divided by the output signal of the fourth photo detector 17, and the result is standardized. As a result, the data analyzer 9 executes linear combination of three standardized signals to find combination coefficients by multivariate analysis, thereby compensating, with higher precision, for the variation due to output variation of the laser diode 1, spatial variation thereof, and the variation due to reflection at the surface of the biological object BL, on the basis of these values.
With the biological information measuring apparatuses shown in
Now, such configurations as shown in
With each of the biological information measuring apparatuses described in the foregoing, there has been shown an example in which a fixed focus lens is used as the objective lens 4, however, use may be made of a variable focus lens. For the variable focus lens, use can be made of a liquid crystal lens constructed by sealing liquid crystals in a space resembling a lens in shape to thereby cause a change of apparent refractive index of the liquid crystals by adjusting a voltage applied thereto. With the liquid crystal lens, a change in refractive index of a constituent material thereof will cause a change in focal length thereof although the shape of the liquid crystal lens remains unchanged.
If the variable focus lens described as above is used as the objective lens 4, a measurement position in the depth-wise direction within the internal tissues of the biological object BL can be suitably set by adjusting a voltage applied to the variable focus lens without moving a position thereof in the direction of the optical axis, thereby simplifying a lens-transfer mechanism.
With each of the biological information measuring apparatuses described in the foregoing, there has been shown an example in which the wavelength tunable laser is used as the light source, however, if a measurement component has been identified, use may be made of a single wavelength laser.
Meanwhile, a data analyzer 9 is provided with a blood glucose value measuring unit 91, a measurement site determination unit 92, a vein pattern detection unit 93, a vein pattern verification unit 94, a vein pattern registration unit 95, and so forth.
The blood glucose value measuring unit 91 measures a blood glucose value on the basis of a detection signal of a confocal optical system, outputted via an A/D converter 8, as previously described.
The measurement site determination unit 92 identifies the skin of the finger FG, and a nail “a” thereof on the basis of the detection signal of the confocal optical system, outputted via the A/D converter 8, to detect the portion of the skin, in the range of the nail epithelium “b” of the finger FG to the first joint “c” thereof, whereupon the measurement site determination unit 92 visualizes to the effect that a measurement site is appropriate by switching color of a display message in a display (not shown), or display color of a lamp from, for example, red to blue.
Thus, by visualizing the portion of the skin, in the range of the nail epithelium “b” of the finger FG to the first joint “c” thereof, as the appropriate measurement site, on the basis of the detection signal of the confocal optical system, and displaying the same, it is possible to decide, and direct the appropriate measurement site by use of a means in common with measurement of the blood glucose value without preparing a separate means for deciding a measurement site, thereby rendering it possible to prevent variation in the measurement site decided at the time of the measurement of the blood glucose value, and to obtain highly reliable measurement results with few measurement error, based on the common measuring condition.
The vein pattern detection unit 93 detects a vein pattern of the finger FG, as one type of biological information on the basis of the detection signal of the confocal optical system, outputted via the A/D converter 8.
The vein pattern verification unit 94 verifies the vein pattern of the finger FG, detected by the vein pattern detection unit 93, against vein patterns of the respective fingers FG of the known subjects under test registered in the vein pattern registration unit 95 in advance. Thereafter, if the vein patterns match each other, the vein pattern verification unit 94 identifies a subject under test on the basis of the registered data while if data on the matching vein pattern is unavailable, the vein pattern together with personal data of a subject under test, such as the name, date of birth, sex, and so forth, is newly registered in the vein pattern registration unit 95 in preparation of the subsequent verification.
Thus, by detecting a vein pattern of the finger FG on the basis of the detection signal of the confocal optical system before verification, thereby identifying a subject under test, it is possible to automatically identify the subject under test by use of the means in common with measurement of the blood glucose value without preparing a separate means for identifying a subject under test.
As a result, it is possible to automatically preserve, and manage measurement data on blood glucose values on a subject-by-subject basis, and to carry out highly accurate correction on the basis of data on an analytical curve unique to an individual subject under test at the time of the measurement of the blood glucose value where necessary.
In
The parallel rays whose optical path is changed by the half mirror 3 before reflection is condensed into a laser beam by a lens 5 to fall on the photo detector 7 comprised of a plurality of photodiodes to be converted into electric signals,
The photo detector 7 converts the laser beam into the electric signals whose intensity and magnitude will increase or decrease according to luminous energy of a laser beam as received, and delivers output signals of the plurality of photodiodes to the A/D converter 8 via the multiplexer 19. The A/D converter 8 converts the electric signals delivered from the plurality of the photodiodes of the photo detector 7 into digital data to be delivered to a data analyzer 9.
The data analyzer 9 executes quantitative analysis of components of the biological object BL on the basis of the plurality of electric signals that are converted and outputted from the respective photodiodes of the photo detector 7 when the biological object BL is irradiated with the respective laser beams at not less than two wavelengths differing from each other.
With the adoption of a configuration shown in
In
As a sectional configuration of the photo detector 7 shown in
With the use of the photo detector 7 provided with the plurality of the photodiodes PD1 to PD4, concentrically circular in shape, as show in
That is, with the use of the photo detector 7 shown in
Further, scattering signals from other than the focal position of the objective lens 4 are obtained as respective signals from the photodiodes PD2 to PD4, positioned on outer peripheries outside the photodiode PD1 capturing a signal large in intensity, and these scattering signals can be utilized for detection of biological information such as information on the surface of a skin, a vein pattern of a finger, and so forth.
In
It is conceivable that a sectional configuration of the photo detector 7 shown in
With the use of the photo detector 7 shown in
It is conceivable that a sectional configuration of the photo detector 7 shown in
With the use of the photo detector 7 shown in
More specifically, with the use of the photo detectors 7 shown in
The laser diode 1 is attached to the one end of the housing 20, and a photo detector 21 formed in the shape of a circle as shown in
In
In the biological information measuring apparatus of a configuration shown in
In the case where the photo detector 21 is as shown in
In the case where the photo detector 21 is as shown in
Further, if a confocal optical system is provided with a mechanism capable of scanning in an x-axis direction, and a y-axis direction, respectively (not shown in
Further, if the confocal optical system is configured so as to be tunable in a z-axis direction as well, this will render it possible to measure scattered and reflected light beams at wavelengths differing from each other (for example, at a wavelength for absorbing a target substance, and a wavelength less absorbing) by use of the same optical system, thereby measuring a blood glucose value on the basis of an analytical curve of glucose absorption.
With the respective biological information measuring apparatuses described in the foregoing, there has been described the case of measuring a blood glucose value in the blood of a human body, however, those biological information measuring apparatuses are also effective for quantitative measurement of blood components other than the blood glucose value, and tissue fluid components.
With those biological information measuring apparatuses, a measurement subject is not limited to the human body, and they are also effective for quantitative measurement of internal substances of an animal, a plant, and so forth, respectively.
Further, a measurement subject is not limited to a biological object, and they are also effective for non-destructive inspection of structure/composition of an agricultural product, a fishery product, a food product, an organic material, and so forth, and quantitative measurement of a chemical substance contained therein.
As described in the foregoing, with the present invention, it is possible to realize a biological information measuring apparatus capable of making adjustment in assembling with relative ease, and precisely fetching measurement data on a desired measurement site of a measurement subject, and the biological information measuring apparatus is suitable for measurement of various components including a blood glucose value in the blood of a human body, and so forth.
With the adoption of such a configuration as described in the foregoing, it is possible to automatically identify a subject under test, and to execute continuous measurement under a common measurement condition having selected a properly identified site at a high S/N ratio for relatively long hours as necessary, and utilization efficiency of the output light of a laser can be improved.
While the present invention has been shown and described with reference to certain exemplary embodiments thereof, other implementations are within the scope of the claims. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Number | Date | Country | Kind |
---|---|---|---|
2010-200535 | Sep 2010 | JP | national |