JP2008113891A - Optical measurement unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate measurement by miniaturizing an optical measurement unit and non-invasively executing measurement and to improve measuring accuracy. <P>SOLUTION: When measuring a blood glucose level using a transmission light 22, a near-infrared laser light absorbed by glucose at a high absorptance and a visible light non-absorbed by glucose are transmitted through a measurement object site 25. After transmitting the lights through the measurement object site a plurality of times by a reflection means 40, this optical measurement unit detects the light transmission amount. This method can secure the sufficient optical path length of the transmission light 22 so as to improve the measurement accuracy, even if the thickness of the measurement object site 25 is thin. The transmission amount of the visible light is used as a reference to correct a state change in the skin tissue of the measurement object site 25. The optical path length is also calculated in the measurement so as to correct the change in the transmission amount due to the change in the optical path length caused by dispersion of the measurement object site. This method can provide the optical measurement unit executing a highly accurate measurement, being miniaturized and invasively executing the measurement. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical measurement unit, and more particularly to an optical measurement unit that is non-invasive, downsized, and has high measurement accuracy.

  There are an invasive method and a non-invasive method as a method for detecting a specific component (for example, sugar) inside the measurement site. As an example of a non-invasive measurement method, a method of optical measurement using near infrared light is known.

  Hereinafter, a blood glucose concentration (blood glucose level) measurement method will be described as an example of an optical measurement method for a specific component.

In order to measure the blood glucose concentration (blood glucose level), there is a method of detecting a difference in absorption amount of near-infrared light by glucose. Specifically, it is a method in which near-infrared light is transmitted through a certain site and blood glucose level is measured from the amount of transmitted light. As the method, a fingertip or the like is considered as the most useful part (see, for example, Patent Document 1 and Patent Document 2).
Japanese Patent No. 3038771 (pages 2, 3 and 1) Japanese Patent No. 3692751 (page 3, FIG. 1)

  When measuring blood glucose level optically, there are a method of using transmitted light and a method of using reflected light as described above, both of which measure the amount of light absorbed by glucose. The blood sugar level is calculated. However, since the amount of absorbed light of glucose is very small, particularly highly sensitive measurement is required in the method using reflected light (diffuse reflected light) with a small amount of light.

  On the other hand, in the method using transmitted light, since the transmitted light can be directly handled, the light use efficiency is high, and the blood sugar level can be detected relatively easily. However, since light is transmitted, the same measurement cannot be performed regardless of the measurement site. For example, in order to obtain a certain degree of measurement sensitivity (measurement accuracy), it is necessary to measure at a part having a certain thickness as a part to be measured.

  However, in a portion having a certain thickness, there may be a tissue such as a bone that does not transmit light or a thick blood vessel. Since transmitted light is strongly influenced by blood components other than glucose (specifically, hemoglobin), measurement at a site where a thick blood vessel is present is not preferable. Therefore, measurement accuracy and reproducibility may not be ensured.

  Conventionally, a fingertip or the like has been used as a measurement site, but even a fingertip may contain bones or thick blood vessels, and the fingertip has a high surface curvature and the measurement position is not stable. For this reason, there is a problem that the reproducibility is lowered.

  In other words, in order to ensure measurement accuracy, it is necessary to be a site that can be measured with capillaries and that does not contain bones. However, in the case of such a region to be measured, the thickness of the tissue through which light passes is thin. Therefore, when the thin tissue is irradiated with light for measurement, there is a possibility that the probability of the light being absorbed by glucose may be lowered, leading to a problem of a decrease in measurement sensitivity.

  The present invention is to solve the above-described problems.

  The present invention has been made in view of the various circumstances described above. First, it is an optical measurement unit that measures the sugar content in a measurement site by transmitting near-infrared laser light to the measurement site. A measuring unit that holds the measurement site between the first holding piece and the second holding piece, and the near-infrared laser beam having a high absorption rate due to the sugar content as outgoing light from the first holding piece. A light emitting unit that emits to the site; a reflection unit that transmits a part of the emitted light by reflection to the site to be measured a plurality of times; and a light receiving unit that receives a part of the emitted light that has passed through the site to be measured. And a control unit that calculates a transmission amount of the emitted light through the measurement site based on a light reception result of the light receiving unit, and converts the calculated amount into the sugar content.

  Second, an optical measurement unit that measures sugar in the measurement site by transmitting near-infrared laser light to the measurement site. The measurement unit includes a first clamping piece and a second clamping piece. A measurement unit that sandwiches the region, a light emitting unit that emits the near-infrared laser light having a high absorptance due to the sugar to the measurement site from the first sandwiching piece serving as a waveguide, and the measurement site Based on the transmitted light, a reflecting means for reflecting a part of the emitted light that has passed through the light and entering the measured site, a light receiving unit that receives light transmitted through the measured site multiple times as transmitted light, and the transmitted light It solves by providing the control part which calculates the permeation | transmission amount in the said to-be-measured site | part of the said emitted light, and converts into the said sugar content.

  Further, the measuring unit is provided with a plurality of the reflecting means.

  Further, a light distribution element is disposed in an optical path from the light emitting unit to the light receiving unit, and the emitted light and the transmitted light are separated by the light distribution element.

  The light distribution element is a polarization beam splitter.

  In addition, a polarization state changing unit is provided in an optical path from the light emitting unit to the light receiving unit, and the transmitted light is changed to a polarization state different from the emitted light.

  The polarization state changing means is a quarter-wave plate.

  The light emitting unit emits a reference light for the near infrared laser light as a part of the emitted light, and the light receiving unit receives a reference transmitted light of the reference light included in the transmitted light. And the controller calculates the sugar content based on the transmitted light and the reference transmitted light.

  According to the present invention, it is possible to provide an optical measurement unit that can be reduced in size, is noninvasive, and has high measurement accuracy.

  First, since the near-infrared laser beam is emitted and transmitted to the measurement site and the glucose concentration of the measurement site is measured based on the amount of transmission, the measurement apparatus can be downsized and non-invasive and easy measurement can be performed. Is possible. In addition, it is possible to measure at a site where a tissue such as a bone that hardly transmits light or a thick blood vessel is not present. The site to be measured is, for example, a thin pleat-like region of tissue such as between the earlobe or the finger of the palm, but the light used for measurement is reflected by reflecting the transmitted light by a mirror and reciprocating in the site to be measured ( The optical path length of transmitted light) can be earned. Therefore, the probability that transmitted light is absorbed by glucose increases, and the measurement accuracy (measurement sensitivity) can be improved.

  Second, by providing a plurality of mirrors that reflect the transmitted light, the number of times the transmitted light is transmitted through the region to be measured can be increased. Thereby, for example, although the measurement site is a thin pleated portion, a long optical path length such as 3 or 4 times the thickness of the tissue can be secured, and the measurement accuracy can be further improved.

  Third, a light distribution element is disposed in the optical path from the light emitting unit to the light receiving unit of the optical measurement unit, and light emitted from the light emitting unit by the light distribution element (emitted light) and light received by the light receiving unit (transmitted light) ). Further, a polarization state changing means is provided in the optical path so that the transmitted light is in a polarization state different from that of the outgoing light. Thereby, even when the area of the measurement site is small and the emitted light and the transmitted light propagate through the same waveguide, the transmitted light can be accurately received.

  Fourthly, since the change due to the state of the skin tissue of the measurement site and the change of the transmission amount due to the change (variation) of the measurement site can be automatically corrected, this also improves the measurement accuracy. Can do.

  More specifically, in addition to near-infrared laser light, reference visible light (visible laser light) is emitted to and transmitted through the measurement site, and the amount of visible light transmitted through the measurement site is measured. The transmission amount of the near infrared laser beam is corrected based on the amount. Thereby, the change of the permeation | transmission amount by the state of skin tissue can be reflected in a measured value, and a measurement error can be reduced. Further, the measurement accuracy can be further improved by detecting the optical path length of the light transmitted through the measurement site and correcting the measurement value based on the amount of change.

  Hereinafter, an example of an embodiment of the optical measurement unit according to the present invention will be described in detail with reference to FIGS. 1 to 6.

  First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing an example of the case where the optical measurement unit according to the first embodiment is adopted in a blood glucose level measuring device, FIG. 1 (A) is an external plan view, and FIG. 1 (B) is FIG. It is the sectional view on the aa line of A).

  For example, a power switch 4, a measurement start / stop button 5, a display unit 2, and the like are provided on one main surface of the external housing 8 of the blood glucose level measuring apparatus 100. The blood glucose level measuring apparatus 100 includes an optical measurement unit 1.

  The optical measuring unit 1 includes a measuring unit 3, a light emitting unit 11, a light receiving unit 12, a control unit 6, and a reflecting means 40, and measures the measurement by transmitting near-infrared laser light to the measurement site. Measure sugar content inside the site.

  The measurement unit 3 serves as a contact portion with the part to be measured and is led out from the external housing 8. Moreover, the measurement part 3 has the 1st clamping piece 31 and the 2nd clamping piece 32, and clamps a to-be-measured site | part by these. Here, as an example, the first sandwiching piece 31 and the second sandwiching piece 32 are configured such that, for example, one end of each is fixed and the other end can be opened and closed. ) To clip.

  The measuring unit 3 is set to be small enough to clamp a limited part of the living body end even when the first holding piece 31 and the second holding piece 32 are opened to the maximum. Moreover, the measurement part 3 is set as the structure which can always clamp a to-be-measured site | part with a predetermined load. By configuring the first sandwiching piece 31 and the second sandwiching piece 32 in a clip shape, it is possible to limit the part of the living body that can be sandwiched by the measuring unit 3, and the measured site is sandwiched by the measuring unit 3 to measure the blood sugar level. The measurement stability is improved.

  One end of the first clamping piece 31 is connected to the light emitting unit 11 and the light receiving unit 12 in the optical measurement unit 1, and the other end is provided with, for example, a mirror 311, a condenser lens 312, and a polarization state changing unit 41. Here, the polarization state changing means is, for example, a quarter-wave plate (hereinafter referred to as λ / 4 plate) 41. The light output from the light emitting unit 11 (hereinafter referred to as outgoing light 20) propagates through the first sandwiching piece 31 serving as a waveguide and is reflected by the mirror 311 as indicated by the arrow in FIG. The light is collected, passes through the λ / 4 plate 41, and is emitted to the site to be measured.

  For example, the second sandwiching piece 32 is provided with the reflecting means 40 at an end portion of the first sandwiching piece 31 that faces the emitting portion (the condensing lens 312 and the λ / 4 plate 41). The first embodiment shows a case where one reflecting means is provided. The reflecting means is, for example, a concave mirror 40 having a main surface on the measurement site side as a reflection surface, reflects a part of the emitted light 20 that has passed through the measurement site, and makes the reflected light 21 incident on the measurement site again. .

  A part of the reflected light 21 transmitted again through the measurement site is collected as transmitted light 22 by the condenser lens 312, reflected by the mirror 311, propagated through the first sandwiching piece 31, and received by the light receiving unit 12.

  The first sandwiching piece 31 serving as a waveguide has a shape (for example, a cylindrical shape) and a material such that the emitted light 20 and the transmitted light 22 to be received do not leak to the outside, and the first sandwiching piece 31 and the second sandwiching piece 32. Constitutes a part of the optical measurement unit 1 together with the light emitting part 11 and the light receiving part 12.

  The light emission part 11 outputs the emitted light 20 containing the 1st emitted light with the high absorption factor by glucose, and the 2nd emitted light used as a reference | standard. Although details will be described later, the light emitting unit 11 includes a semiconductor laser diode as a light emitting element, and outputs a near-infrared laser beam having a single wavelength as the first emitted light. The near-infrared laser beam employs a wavelength of, for example, 1580 nm, which has a high absorption rate by glucose in the transmitted light.

  The light emitting unit 11 includes another semiconductor laser diode or LED (Light Emitting Diode), and outputs visible light as the second emitted light. In the present embodiment, for example, laser light having a wavelength of 660 nm (visible laser light) is employed as visible light. This wavelength is a wavelength that has no or very little absorption with respect to glucose, is long to some extent, and is a wavelength at which a certain amount of attenuation is recognized by the skin tissue of the measurement site. By using the visible light as a reference, it is possible to correct “variation” of the near-infrared laser light due to the measurement site.

  The light receiving unit 12 includes, for example, a light detector (Photo Detector), transmits the measurement target portion of the first emitted light (near infrared laser light), is reflected by the concave mirror 40, and transmits the measurement target portion again. The light incident on the first sandwiching piece 31 is received as first transmitted light (hereinafter referred to as laser transmitted light). Further, the second outgoing light (visible light) is transmitted through the measurement site, reflected by the concave mirror 40, and again transmitted through the measurement site and incident on the first clamping piece 31 as second transmitted light (hereinafter referred to as “second transmission light”). (Visible transmitted light).

  By detecting the visible transmitted light, the light receiving unit 12 can calculate the transmission amount (transmittance) of visible light in the measurement site. Therefore, the transmission amount of near-infrared laser light can be corrected based on this.

  Further, in order to further improve the measurement accuracy, for example, an optical path length detection unit 19 or the like may be provided, and the thickness of the actual measurement site may be measured and corrected accordingly.

  Explaining an example, the optical path length detection unit 19 detects the actual thickness of the site to be measured (the optical path length of the light that passes through the site to be measured) by the first clamping piece 31 and the second clamping piece 32. For example, an angle detector.

  The angle detector 19 detects an angle θ formed by the first clamping piece 31 and the second clamping piece 32. The angle detection unit 19 includes, for example, a digital counter that counts pulses from the encoder, and a rotary plate provided with a slit, and the first clamping piece 31 and the second clamping piece 32 clamp the measurement site. These movement amounts are converted into distances according to the angle θ.

  The optical path length detection unit is not limited to the angle detection unit 19 and may be a unit that converts the movement amount of the first clamping piece 31 and the second clamping piece 32 into a distance, such as a micrometer. In the case where the measurement unit 3 is not clip-shaped and is configured such that the measurement site is clamped by the slide of the first clamping piece 31 and the second clamping piece 32, for example, the optical path length of the measurement site is detected by the slide amount. it can. However, it is possible to stabilize the load on the part to be measured by making the measuring unit 3 a clip. Considering the advantage that the measurement site 3 can be clamped and limited to some extent, the present embodiment will be described by taking the case where the angle detection unit 19 is employed as an example.

  The control unit 6 is configured by, for example, a semiconductor integrated circuit integrated on a printed circuit board, and includes an arithmetic processing unit. The arithmetic processing unit calculates the transmission amount (or transmittance) of the near-infrared laser light at the measurement site from the light amount of the laser transmission light detected by the light receiving unit 12.

  Further, the arithmetic processing unit calculates the transmission amount (or transmittance) of visible light in the measurement site from the light amount of the visible transmission light detected by the light receiving unit 12.

  Further, the arithmetic processing unit calculates the optical path length of the near-infrared laser light in the measurement site based on the angle θ formed by the first clamping piece 31 and the second clamping piece 32 detected by the angle detection unit 19.

  Then, the transmission amount of near-infrared laser light (hereinafter referred to as laser transmission amount) is corrected based on the transmission amount of visible light (hereinafter referred to as visible transmission amount) and the optical path length.

  Although details will be described later, based on the amount of change in visible transmission, by correcting the amount of laser transmission that has passed through the same site to be measured, changes in the site to be measured and changes in skin tissue at the site to be measured The measurement error due to “variation” can be reduced.

  Further, by correcting the laser transmission amount based on the optical path length of the measurement site, it is possible to reduce measurement errors due to “variation” of the measurement site.

  Further, as described above, the arithmetic processing unit converts the corrected laser transmission amount into blood glucose level data, and the control unit 6 displays the blood glucose level data on the display unit 2 by the display driver.

  The display unit 2 is connected to a display driver that is a part of the control unit 6. The display unit 2 is, for example, an LCD (Liquid Crystal Display) panel, an organic EL (Electronic Luminescent) display panel, etc., and displays a blood glucose level and other measurement information (for example, notification of measurement error, date and time) so that the measurer can recognize it. Anything can be used. In addition, a power supply unit (not shown) connected to the control unit 6 is provided. The power source is charged by an AC adapter, a battery, or a combination thereof.

  In addition, it is good also as a structure by which a contact detection sensor is provided in the 1st clamping piece 31 and the 2nd clamping piece 32, and a measuring apparatus is operated after a normal contact is detected.

  With reference to FIG. 2, the optical measurement unit 1 of this embodiment is demonstrated. FIG. 2A is a schematic view showing a state in which the emitted light 20 and the transmitted light 22 pass through the measurement site 25 in a state where the measurement site 25 is sandwiched by the measurement unit 3, and FIG. FIG. 2 is a schematic diagram illustrating an example of a main part of the optical measurement unit 1.

  As described above, the emitted light 20 output from the semiconductor laser diode LD1 passes through the measurement site 25, is reflected by the concave mirror 40, and is incident again on the measurement site 25, and is transmitted to the photodetector PD as transmitted light 22. Is received.

  As shown in FIG. 2B, the emitted light 20 is converted into parallel light by the collimator lens 43 and passes through the light distribution element 42. The light distribution element is, for example, a polarizing beam splitter (PBS) 42. A λ / 4 plate 41 is provided in the optical path from the light emitting unit 11 (semiconductor laser diode LD) to the light receiving unit 12 (photodetector PD).

  In the first embodiment, since the emitted light 20 and the transmitted light 22 propagate through the same waveguide (first sandwiching piece 31), they should be received by the polarization beam splitter (hereinafter referred to as PBS) 42 and the λ / 4 plate 41. The transmitted light 22 is separated.

  That is, when the outgoing light 20 having a linear polarization state, for example, P-polarized light passes through the λ / 4 plate 41, it becomes circularly polarized light and passes through the measurement site 25. A part of the outgoing light 20 is reflected by the concave mirror 40. In the present embodiment, the concave mirror 40 is employed as the reflecting means, and the beam of the reflected light 21 incident on the measurement site 25 can be narrowed down. The reflected light 21 passes through the measurement site 25 again, passes through the λ / 4 plate 41 as the transmitted light 22, and is in a linear change state rotated 90 degrees from the linearly polarized state of the outgoing light 20. That is, by passing through the λ / 4 plate 41 twice, the linearly polarized state of the transmitted light 22 becomes S-polarized light and can be separated from the emitted light 21 by the PBS 42. The separated transmitted light 22 is detected by the photodetector PD through the collimator lens 44.

  Part of the emitted light 20 that has been transmitted through the measurement site 25 multiple times (here, twice) by reflection propagates through the first sandwiching piece (waveguide) 31 as transmitted light 22 and is received by the photodetector PD. . That is, the optical path length of the reflected light 21 is also added as the optical path length of the transmitted light 22, which is almost twice the thickness of the actual measurement site 25.

  In order to measure the blood glucose level, it is efficient to detect the glucose concentration in the living body. In addition, when measuring blood sugar levels non-invasively (without blood sampling), light in a wavelength band that is transparent to the human body is used. In the case of glucose, some spectra of near-infrared light are used. It is known to have light absorption characteristics. Therefore, in the present embodiment, near-infrared laser light is employed as the emitted light 20 and is transmitted through the measurement site 25 to detect the absorption rate by glucose, thereby measuring the blood glucose level.

  At this time, the thicker the portion to be measured 25, the longer the optical path length of the transmitted light 22, and the higher the probability of being absorbed by glucose. In the present embodiment, the reflected light 21 from the concave mirror 40 is also transmitted to the measurement site, whereby a part of the emitted light 20 is reciprocated in the measurement site 25, thereby increasing the optical path length (FIG. 2A). .

  Although FIG. 2 shows an example in which the λ / 4 plate 41 is disposed between the PBS 42 and the measurement site 25, the present invention is not limited to this. That is, the transmitted light 22 only needs to be in a linearly polarized state different from that of the outgoing light 20 before entering the PBS 42, and therefore, for example, a λ / 4 plate 41 may be disposed between the measurement site 25 and the concave mirror 40.

  As will be described later, visible light (visible laser light) is emitted as the emitted light 20 in addition to the near-infrared laser light. Therefore, the optical measurement unit 1 has the configuration of FIG. 2 for each laser beam, but the concave mirror 40 and the λ / 4 plate 41 are common.

  FIG. 3 is a schematic diagram showing a blood sugar level measurement site 25 and a blood sugar level measuring apparatus 100.

  The measurement site 25 sandwiched by the blood sugar level measuring apparatus 100 of the present embodiment will be described. For example, the thickness is relatively thin, such as between fingers (FIG. 3A) and earlobe (FIG. 3B). It is preferable that the pleated portion is the measurement site 25. This is because the measurement error can be reduced when the optical path length of the light passing through the measurement site is shorter.

  When measuring the glucose concentration based on the amount of transmitted light absorbed by glucose, it is desirable that the portion to be measured that is the optical path length of the transmitted light is thick to some extent because the probability of being absorbed by glucose increases.

  However, for example, in a human body, there are many cases where a tissue that does not transmit light, such as bones, or a thick blood vessel exists in such a measurement site. In particular, the transmitted light is strongly influenced by blood components other than glucose (specifically, hemoglobin), so measurement at a site where a thick blood vessel exists is not preferable, and measurement accuracy and reproducibility may not be ensured.

  Therefore, in the present embodiment, a measurement is possible with a capillary vessel as the measurement site, and a site where no bone or the like is present is employed. Specifically, it is a pleated part such as a finger or an earlobe as described above.

  Then, in order to increase the probability of being absorbed by glucose, the outgoing light 20 is reflected by the concave mirror 40 and transmitted again to the measurement site. And the transmitted light 22 is received and glucose is measured. That is, although it is a thin site to be measured, the optical path length can be increased by adding the optical path length of the reflected light 21, so that the probability of absorption by glucose can be increased and the measurement accuracy can be improved (see FIG. 2). ).

  Each of the first clamping piece 31 and the second clamping piece 32 has a clip-like configuration in which one end is fixed by, for example, the angle detection unit 19 and the other end can be opened and closed. . At this time, reproducibility can be improved by always applying a predetermined load to the measurement site 25.

  Furthermore, the angle θ formed by the first sandwiching piece 31 and the second sandwiching piece 32 is set so small that the maximum angle can sandwich a limited part of the living body end. More specifically, even when the measuring unit 3 is opened to the maximum, the measurement site can be limited to some extent by adopting a configuration in which only a thin and limited site such as a fold-like part of a living body can be sandwiched. For example, as the maximum opening angle between the first sandwiching piece 31 and the second sandwiching piece 32, the condenser lens 312 located at the tip of the first sandwiching piece 31 and the condenser lens 322 located at the tip of the second sandwiching piece 32. The measurement part sandwiched between them is limited to a specific part such as a finger or an earlobe, for example, depending on the part to be measured. It is possible to avoid a large “variation” in the measured value.

  FIG. 4 is an example of a circuit block diagram illustrating an outline of the optical measurement unit 1 of the present embodiment.

  The light emitting unit 11 includes a first light emitting element LD1 and a second light emitting element LD2. The first light emitting element LD1 is, for example, a semiconductor laser diode, and the second light emitting element LD2 is a semiconductor laser diode or LED. Here, a case where a semiconductor laser diode is employed as the second light emitting element LD2 will be described as an example.

  The first light emitting element LD1 is driven by the laser driver 63a of the control unit 6 and outputs first emitted light (near infrared laser light) 201 having an emission wavelength of, for example, 1580 nm. The second light emitting element LD2 is driven by the laser driver 63b of the control unit 6, and outputs second emitted light (visible light: laser light) 202 having an emission wavelength of, for example, 660 nm. Note that the emission wavelength of the second light emitting element LD2 is a wavelength different from that of the near-infrared laser light 201, and has a wavelength that does not absorb or very little absorbs glucose, and has a certain degree of attenuation by skin tissue. Although not limited, a semiconductor laser diode having an emission wavelength of 660 nm is common and inexpensive.

  Part of the near-infrared laser light 201 output from the first light emitting element LD1 passes through the PBS or analyzer 24 that aligns the polarization of the near-infrared laser light 201, and further collimator lens 43a, half mirror 15a, and FMD. (Front Monitor Diode) 16a is input to an APC (Auto Power Control) 13a.

  Part of the visible light 202 output from the second light emitting element LD2 is input to an APC (Auto Power Control) 13b via a collimator lens 43b, a half mirror 15b, and an FMD (Front Monitor Diode) 16b.

  The APCs 13a and 13b perform control such as maintaining the power of the near infrared laser beam 201 and the visible light 202 constant, respectively.

  The collimator lens 43a and the PBS 42a are provided corresponding to the first light emitting element LD1, and the collimator lens 43b and the PBS 42b are provided corresponding to the second light emitting element LD2. The near-infrared laser beam 201 becomes parallel light by the collimator lens 43a and enters the PBS 42a, and the visible light 202 also becomes parallel light by the collimator lens 43b and enters the PBS 42b (see FIG. 2).

  The near-infrared laser beam 201 and the visible light 202 are combined by the dichroic mirror 17 that passes through one of the PBSs 42a and 42b provided in correspondence with each other and then reflects the other. The light passes through the plate 41 and is emitted from the end of the first clamping unit 31 to the measurement site 25. A part of the emitted light 20 in the measurement site 25 is absorbed by glucose and slightly attenuated by the skin tissue, and is emitted from the measurement site 25 and provided at the end of the second clamping piece 32. Reflected by the concave mirror 40. The reflected light 21 passes through the measurement site 25 again, and a part of the reflected light 21 is absorbed by glucose and is attenuated by the skin tissue to be emitted from the measurement site 25 as transmitted light 22. .

  In this way, by irradiating the measurement site 25 with the emitted light 20 obtained by synthesizing the near-infrared laser beam 201 and the visible light 202, the optical path through which the emitted light 20 passes through the measurement site 25 can be unified. Therefore, the amount of basic transmitted light 22 can be measured at a site where blood glucose is actually measured.

  In addition, even in the measurement using the near-infrared laser beam 201 and the visible light 202 having different wavelengths, the measurement only needs to be performed once. Compared to the case where the near-infrared laser beam 201 and the visible light 202 are sequentially switched and measured. Thus, the measurement time can be shortened. Further, since the near-infrared laser beam 201 cannot be visually recognized, it can be recognized that the visible light 202 is being emitted at the same time that the measurement is being performed.

  The transmitted light 22 emitted from the part to be measured 25 passes through the λ / 4 plate 41, thereby changing the straight line state different from that of the emitted light 20, and enters the dichroic mirror 17 in this state.

  The transmitted light 22 is separated into a first transmitted light (laser transmitted light) 221 and a second transmitted light (visible transmitted light) 222 by the dichroic mirror 17 and received by the light receiving unit 12.

  The light receiving unit 12 includes a first light receiving unit PD1 and a second light receiving unit PD2. The laser transmitted light 221 separated by the dichroic mirror 17 is incident on the PBS 42a again. Since the laser transmitted light 221 (transmitted light 22) is in a linearly polarized state different from that of the emitted light 21 (near infrared laser light 201), only the laser transmitted light 221 is separated by the PBS 42a in the first light receiving unit PD1. Detected. The detected amount of received laser transmitted light 221 (hereinafter referred to as laser transmission amount N) is an actual measurement value.

  Similarly, the separated visible transmitted light 222 is incident on the PBS 42b again. Since the visible transmitted light 222 (transmitted light 22) is in a linearly polarized state different from that of the emitted light 21 (visible light 202), only the visible transmitted light 222 is detected by the second light receiving unit PD2 after being separated by the PBS 42b. .

  Thus, by separating the outgoing light 20 and the transmitted light 22 by polarization, the area of the measurement site is small, and even when the outgoing light and the transmitted light propagate through the same waveguide, the transmitted light can be accurately measured. Can be received.

  Each of the first light receiving part PD1 and the second light receiving part PD2 is, for example, an InGaAs photodiode or the like, and converts each received transmitted light 22 into an electric signal. The electric signal is proportional to the intensity of the received light, is amplified by the amplifiers 14 a and 14 b, and is output to the A / D converter 62 of the control unit 6.

  The control unit 6 includes a DSP (Digital signal processor) 61, an A / D conversion circuit 62, laser drivers 63 a and 63 b, and an arithmetic processing unit 65. The control unit 6 also includes a display driver 64 for outputting data such as measurement results to the display unit, other circuits (not shown) necessary for other controls, and the like.

  A signal (reception signal) based on the amount of received light amplified by the optical measurement unit 1 is converted into a digital signal by the A / D conversion circuit 62 and input to the arithmetic processing unit 65 in the DSP 61.

  The arithmetic processing unit 65 calculates the glucose concentration at the measurement site based on the received signal. In the present embodiment, the glucose concentration is calculated based on the absorbance I using near-infrared laser light 201 having a wavelength that is largely absorbed by glucose. The absorptance I can be obtained from the amount of emitted light (intensity) of the near-infrared laser light 201 emitted from the light emitting unit 11 and the amount of received light (intensity) of the laser transmitted light 221 that has passed through the measurement site 25. Assuming that the intensity of the emitted light 20 having the wavelength λ emitted to the measurement site 25 is L0 (λ) and the intensity of the transmitted light 22 having the received wavelength λ is L (λ), the absorbance I ( λ) is obtained by ln (L (λ) / L0 (λ)) (in the case where the emitted light 20 is constant, the received light intensity itself is equivalent to the absorbance).

  The absorbance I has a predetermined correlation with the glucose concentration. Therefore, the glucose concentration of the measurement site 25 can be calculated by causing the control unit 6 to hold the correlation function between the absorbance I and the glucose concentration.

  Further, the control unit 6 corrects the change in the laser transmission amount N (measured value) accompanying the change in the state of the skin tissue of the measurement site 25. Furthermore, in order to improve the measurement accuracy, it is preferable to correct the change in the laser transmission amount N accompanying the change in the optical path length due to the change in the measurement site 25. This will be described below.

  The change in the laser transmission amount N accompanying the change in the state of the skin tissue is corrected by the transmission amount of the visible light 202 emitted to the same measurement site 25 (hereinafter, the visible transmission amount V).

  As described above, the visible light 202 has a wavelength that is not absorbed by glucose and is attenuated to some extent by the skin tissue. Therefore, the reference transmission state can be measured by the change amount of the visible transmission amount V.

  More specifically, the permeation amount (hereinafter referred to as reference permeation amount) of a specific part of the living body is measured in advance and held in the control unit 6, and this is compared with the visible permeation amount V. Thereby, the change amount of the visible transmission amount V (difference between the visible transmission amount and the reference transmission amount) is the change (deviation) of the measured region 25 itself, the change of the state of the skin tissue, or the tissue change of the skin tissue. It can be measured as the first shift amount shown.

  Since the near-infrared laser beam 201 passes through the same site to be measured 25 as the visible light 202, the measured laser transmission amount N (measured value) includes the first reference shift amount. Therefore, the arithmetic processing unit 65 performs a calculation for correcting the laser transmission amount N based on the first shift amount.

  In addition, the arithmetic processing unit 65 determines the optical path length L of the near-infrared laser light 201 in the measurement site 25 based on the angle θ formed by the first clamping piece 31 and the second clamping piece 32 detected by the angle detection unit 19. Calculate (see FIG. 3B). If the part to be measured 25 varies, the amount of laser transmission N transmitted through the part to be measured 25 also changes, causing a measurement error. In the present embodiment, an expected value is stored in the control unit 6 in advance, and by calculating the amount of change (second shift amount) of the optical path length L of the measured region 25 from the expected value, Even if there is "variation" in the measurement site, this can be corrected.

  As a result, even when the measurement site 25 changes, for example, with a fingernail portion, between fingers, or an earlobe, the laser is always corrected with the amount of change peculiar to that site and the change in optical path length. A transmission amount N can be obtained.

  More specifically, the arithmetic processing unit 65 calculates the first shift amount and the second shift amount according to the following equation (1), and the laser transmission amount N due to the change in the state of the skin tissue or the like or the change in the optical path length. The blood glucose level data G from which the measurement error is eliminated is calculated.

G = f (N, A, V) (1)
Here, N: laser transmission amount, A: angle (θ) formed by the first clamping piece 31 and the second clamping piece 32, and V: visible transmission amount.

  The control unit 6 causes the display driver 64 to display the blood glucose level data G as a measurement result on the display unit. Further, the measurement unit 6 performs various known controls corresponding to pressing of a measurement start / stop button, monitoring of a measurement state, and the like. Further, when a contact detection sensor is provided in the measurement unit 3, the control unit 6 performs a process related to detection of a contact state, such as starting a measurement process (laser drive or the like) after detecting normal contact.

  Although not shown, the optical measurement unit 1 may be provided with a temperature detector (for example, a temperature sensor). The temperature sensor measures the temperature of the measurement site 25 (or in addition to the outside air temperature). The absorption characteristics of glucose by the near-infrared laser light 201 vary with temperature. Therefore, the temperature is measured by the temperature sensor before the blood glucose level is measured, and the wavelength of the near infrared laser beam 201 is corrected within a minute range from the measurement result. Note that visible light is not affected by temperature and does not require temperature correction.

  For example, since the oscillation wavelength of the near-infrared laser beam 201 emitted from the first light emitting element LD1 has a characteristic that changes depending on the current supplied to the first light emitting element LD1 or the temperature of the first light emitting element LD1, it is measured in advance. The temperature or drive current of the first light emitting element LD1 that emits the near-infrared laser light 201 is controlled based on the temperature dependence of the absorption characteristics of glucose. For example, when controlling with the drive current of the near-infrared laser beam 201, the laser drive amount is calculated and fed back to the laser driver 63a. Thereby, the near-infrared laser beam 201 is selected with the most efficient wavelength within the range satisfying the wavelength condition of the present embodiment according to the temperature of the measurement site 25, and is shifted by, for example, several nm. Thereby, a more accurate blood glucose level can be measured.

  In the above example, the case where the near-infrared laser beam 201 and the visible light 202 are synthesized by the dichroic mirror 17 to be the emitted light 20 has been described. However, the present invention is not limited thereto, and the near-infrared laser beam 201 and the visible light are combined. 202 may be sequentially output individually at a predetermined timing.

  If the measurement unit 3 maintains the state where the measurement site 25 is sandwiched, the near-infrared laser beam 201 and the visible light 202 may be emitted with a predetermined time difference. The laser transmitted light 221 can be corrected.

  In this case, since it is not necessary to synthesize the emitted light 20, the dichroic mirror 17 is unnecessary. Further, for example, when parallel light is used as measurement light (light received by the light receiving unit 12), a semiconductor laser diode is diffused light, so a collimator lens is required. However, when measuring diffused light as it is, a lens is used. Is unnecessary.

  Then, near-infrared laser light 201 and visible light 202 are output from the first light-emitting element LD1 and the second light-emitting element LD2, respectively, with a predetermined time difference at the timing created by the CPU that controls light emission.

  In the light receiving unit 12 also, the laser transmitted light 221 and the visible transmitted light 222 are individually received, so that the dichroic mirror 23 is unnecessary.

  Further, the light detector of the light receiving unit 12 may be configured by one photodiode PD that can receive and detect two wavelengths of the laser transmitted light 221 (1580 nm) and the visible transmitted light 222 (660 nm). When a photodiode is employed for the light receiving unit 12, generally, the photodiode has a narrow light receiving sensitivity, so that photodiodes PD1 and PD2 are provided corresponding to two wavelengths as shown in FIG. However, if light can be received by one photodiode, it is not necessary to separate them, and only one amplifier is required, which can contribute to reduction in the number of components and downsizing of the apparatus.

  In the present embodiment, for example, a long optical path length required for an optical measurement unit such as a spectroscopic analyzer or an FTIR analyzer, or an operating part such as a mirror is unnecessary, and downsizing can be achieved. In addition, since the transmitted light of the laser light having a single wavelength is received, it is not necessary to split the light with a diffraction grating or the like, and the light receiving side can be composed of, for example, a lens and a photo detector. Therefore, the optical measurement unit 1 can be reduced in size and weight. For example, when the optical measurement unit 1 is employed in a blood glucose level measuring apparatus, portability can be greatly improved. The size is small enough to fit in the palm of the hand and can be carried and operated with one hand.

  Furthermore, in the present embodiment, only the absorption spectrum of glucose is measured, and unnecessary spectrum is not measured, so that the measurement time can be shortened.

  Next, a second embodiment of the present invention will be described with reference to FIG. In the second embodiment, the measuring unit 3 is provided with a plurality of reflecting means 40. The description of the same components as those in the first embodiment is omitted.

  FIG. 5 is a schematic diagram illustrating an example of a main part of the optical measurement unit 1 according to the second embodiment.

  In order to increase the probability of being absorbed by glucose and improve the measurement accuracy, it is desirable that the optical path length of the transmitted light 22 (reflected light 21) is long. Therefore, the measurement unit 3 is provided with two concave mirrors 40 (a first concave mirror 401 and a second concave curve 402).

  The first concave mirror 401 is provided on the second sandwiching piece 32, and the second concave mirror 402 reflects the emitted light 20 output from the light emitting element LD by the first concave mirror 401, and further reflects the reflected light 21. Adjustment is made so as to pass through the measurement site 25. The transmitted light 22 that has passed through the measurement site 25 three times is received by the light receiving unit 12 through the lens 44 and the mirror 321 with the second sandwiching piece 32 as a waveguide. That is, the optical path length of the transmitted light 22 can be ensured to be three times the optical path length of the measurement site 25.

  In this case, since the waveguides of the outgoing light 20 and the transmitted light 22 are different from each other, it is not necessary to separate them by polarized light. Specifically, a λ / 4 plate or PBS is not necessary.

  As described above, when the measurement site 25 can be secured to some extent, the optical path length of the transmitted light 22 can be gained by repeatedly arranging a plurality of concave mirrors in the first clamping unit 31 and the second clamping unit 32. . Further, if the number of times of transmission through the measurement site 25 is an odd number, the outgoing light 20 and the transmitted light 22 propagate through different waveguides, so that separation by polarization is unnecessary.

  Next, a third embodiment of the present invention will be described with reference to FIG. In the third embodiment, the measuring unit 3 is provided with three reflecting means 40. The description of the same components as those in the first embodiment is omitted.

  FIG. 6 is a schematic diagram illustrating an example of a main part of the optical measurement unit 1 according to the third embodiment.

  When three concave mirrors 40 (401, 402, 403) are provided in the measurement unit 3, the first concave mirror 401 is provided in the second clamping piece 32, the second concave mirror 402 is provided in the first clamping unit 31, and the first Three concave mirrors 403 are provided in the second clamping unit 32. The second concave curve 402 is that the emitted light 20 emitted from the light emitting element LD is reflected by the first concave mirror 401, further reflects the reflected light 21, passes through the measurement site 25, and enters the third concave curve 403. To be adjusted. The third concave surface strength 403 is adjusted so that the reflected light 21 is further reflected and transmitted through the measurement site 25.

  Then, the transmitted light 22 that has passed through the measurement site 25 four times enters the first holding piece 31 through the lens 44, is separated from the emitted light 20 by the PBSs 42a and 42b, and the mirror 311 ′, and enters the photodetector PD. Is received. That is, the optical path length of the transmitted light 22 can be ensured to be four times the optical path length of the measurement site 25.

  In this case, since the waveguides of the outgoing light 20 and the transmitted light 22 are the same, separation by polarization is necessary as in the first embodiment, and each of the laser transmitted light 221 and the visible transmitted light 222 is changed to near red. PBSs 42a and 42b are provided to separate the external laser beam 201 and the visible light 202 from each other.

  Further, the λ / 4 plate 41 is provided between the second concave mirror 402 and the measurement site 25, for example. Thereby, the transmitted light 22 in a linearly polarized state different from the emitted light 20 can be obtained.

  Furthermore, in the third embodiment, the polarization state changing means may be a half-wave plate (λ / 2) plate. For example, when P-polarized light passes through the λ / 2 plate, it changes to S-polarized light. Therefore, the λ / 2 plate is provided at a position where light passes only once on the optical path between the light emitting unit 11 and the light receiving unit 12. For example, it is between the part to be measured 25 and the lens 44 of the first clamping unit 31 through which the reflected light 21 (transmitted light 22) reflected by the third concave mirror 403 passes.

As described above, the blood sugar level measuring apparatus employing the optical measuring unit 1 has been described as an example. However, the present invention is not limited to this, and the optical measuring unit 1 according to the present embodiment may be employed in an apparatus for measuring fruit fructose, for example.

It is explanatory drawing which shows one Embodiment at the time of using the optical measuring unit which concerns on this invention for a blood glucose level measuring apparatus, (A) is an external appearance top view, (B) is the sectional view on the aa line of (A). It is. It is the schematic which shows the main components of an optical measurement unit. It is explanatory drawing which shows the state by which the to-be-measured site | part was pinched | interposed by the blood glucose level measuring apparatus which employ | adopted the optical measurement unit, (A) is the schematic diagram by which the to-be-measured part was set between the fingers of a hand, (B) is an earlobe It is the schematic diagram made into the to-be-measured site | part. 1 is a circuit block diagram showing a first embodiment of an optical measurement unit according to the present invention. It is the schematic which shows 2nd Embodiment of the optical measurement unit which concerns on this invention. It is the schematic which shows 3rd Embodiment of the optical measurement unit which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical measuring unit 2 Display part 3 Measuring part 4 Power switch 5 Measurement start / stop button 6 Control part 8 External housing 11 Light emitting part 12 Light receiving part 13a, 13b APC
14a, 14b Amplifier 15a, 15b Half mirror 16a, 16b FMD
17 Dichroic mirror 19 Optical path length detector (angle detector)
20 outgoing light 201 near infrared laser light (first outgoing light)
202 Visible light (second outgoing light)
21 Reflected light (emitted light)
22 Transmitted light 221 Laser transmitted light (first transmitted light)
222 Visible transmitted light (second transmitted light)
25 measurement site 31 first clamping piece 32 second clamping piece 311, 311 ′, 321 mirror 312, 322 condenser lens 40, 401, 402, 403 concave mirror (reflecting means)
41 λ / 4 plate (polarization state changing means)
42a, 42b PBS (polarization beam splitter)
43a, 43b, 44a, 44b Collimator lens 61 DSP
62 A / D converter circuit (A / D converter)
63a, 63b Laser driver 64 Display driver 65 Arithmetic processing unit 100 Blood glucose level measuring device LD Laser diode (light emitting unit)
LD1 Laser diode (first light emitting part)
LD2 Laser diode (second light emitting part)
PD photodiode (light receiving part)
PD1 photodiode (first light receiving part)
PD2 photodiode (second light receiving part)

Claims (8)

An optical measurement unit that measures sugar in the measurement site by transmitting near-infrared laser light to the measurement site,
A measurement unit for clamping the measurement site by the first clamping piece and the second clamping piece;
A light emitting unit that emits the near-infrared laser light having a high absorption rate due to the sugar as the emitted light from the first clamping piece to the measurement site;
Reflecting means for transmitting a part of the emitted light into the measurement site a plurality of times by reflection;
A light receiving unit for receiving a part of the emitted light transmitted through the measurement site;
A control unit that calculates the amount of transmission of the emitted light in the measurement site based on the light reception result of the light receiving unit, and converts it into the sugar content;
An optical measurement unit comprising: An optical measurement unit that measures sugar in the measurement site by transmitting near-infrared laser light to the measurement site,
A measurement unit for clamping the measurement site by the first clamping piece and the second clamping piece;
A light emitting unit that emits the near-infrared laser light having a high absorption rate due to the sugar to the measurement site from the first sandwiching piece serving as a waveguide;
Reflecting means for reflecting a part of the emitted light transmitted through the measurement site and entering the measurement site;
A light receiving unit that receives light transmitted through the measurement site a plurality of times as transmitted light;
A control unit that calculates a transmission amount of the emitted light in the measurement site based on the transmitted light, and converts the calculated amount into the sugar;
An optical measurement unit comprising:   The optical measurement unit according to claim 2, wherein a plurality of the reflection means are provided in the measurement unit.   The optical measurement unit according to claim 2, wherein a light distribution element is disposed in an optical path from the light emitting unit to the light receiving unit, and the emitted light and the transmitted light are separated by the light distribution element.   The optical measurement unit according to claim 4, wherein the light distribution element is a polarization beam splitter.   The optical measurement unit according to claim 4, wherein a polarization state changing unit is provided in an optical path from the light emitting unit to the light receiving unit, and the transmitted light is set to a polarization state different from that of the emitted light.   The optical measurement unit according to claim 6, wherein the polarization state changing unit is a quarter-wave plate.   The light emitting unit emits a reference light for the near-infrared laser light as a part of the emitted light, and the light receiving unit detects a reference transmitted light of the reference light included in the transmitted light. The optical measurement unit according to claim 2, wherein the control unit calculates the sugar content based on the transmitted light and the reference transmitted light.

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