JP2006223516A - Eyeball observation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To fix a pupil diameter without taking time in the case of successively irradiating an eyeball with the light of mutually different light emission wavelength bands. <P>SOLUTION: An eyeball observation device comprises: a plurality of light sources 106 having the plurality of light sources of the mutually different light emission wavelength bands to the eyeball; a light source switching means 105 for successively switching the light sources by controlling the ON and OFF of the light sources; a light source current control means 104 for controlling the current of the respective light sources; and a pupil diameter adjusting means 101 for outputting the current value of the light source to the light source current control means 104 so as to fix the pupil diameter when the light source switching means 105 switches the light source which is ON. The pupil diameter adjusting means 101 can fix the pupil diameter even in the case that the light source switching means 105 successively switches the light sources by selecting and outputting the current of the respective light sources so as to fix illuminance. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technique for making a pupil diameter constant when observing an eyeball by sequentially irradiating light of different emission wavelength bands to the eyeball.

  Conventionally, blood collected with a syringe at hospitals and clinics is measured with a high-accuracy blood glucose analyzer, and blood collected by puncturing a fingertip at home or on the go is measured with a portable simple blood glucose meter. Seeking blood glucose level. In any of the methods, since it is painful to hurt the human body, it is a mental and physical disorder in managing blood glucose levels. Consideration should also be given to the risk of infection and the disposal of waste with blood.

  Accordingly, various non-invasive methods for measuring blood glucose levels have been proposed. As a measuring means, a method utilizing an optical rotation angle of glucose, absorbance or reflectance of infrared light or visible light, electromagnetic waves, sound waves, electrical characteristics, etc. has been proposed. As measurement sites, skin surfaces such as arms, fingers and ears, eyeballs, nails and saliva have been proposed.

  In Patent Document 1, biological features that correlate with changes in blood glucose level from the iris portion of the eyeball image at the time of each light irradiation, which is obtained by sequentially irradiating the eyeball with light of different emission wavelength bands and imaged by imaging means such as a CCD. The amount is measured, and the blood glucose level is estimated from a correlation table between the blood glucose level prepared in advance at the time of each light irradiation and the biological feature amount. At this time, in order to calculate the biometric feature amount from the iris portion, if the pupil diameter changes, the image of the iris portion changes, and a reliable biometric feature amount cannot be obtained. Therefore, it is necessary to make the pupil diameter as constant as possible and to reduce the change in the image of the iris portion.

  On the other hand, as a technique for making the pupil diameter constant, there is a technique as described in Patent Document 2. In FIG. 1 of Patent Document 2, in an imaging apparatus, infrared light is applied to a photographer's eyeball looking into a finder screen, reflected light of the eyeball is incident on a photoelectric element array, and the pupil is based on an output signal of the photoelectric element array. The determination circuit detects the photographer's pupil diameter, and when the pupil diameter is larger than a predetermined value, the control circuit issues a control signal for increasing the brightness of the finder screen (conversely, when the pupil diameter is smaller than the predetermined value). A control signal for reducing the brightness of the finder screen is issued), and so-called feedback control is performed.

  FIG. 20 shows a block diagram of a conventional non-invasive blood sugar measuring device. In FIG. 20, a plurality of light sources 106 includes a plurality of light sources having different emission wavelength bands, a light source current control unit 104 controls the current of each light source to a current value output from the feedback light source current setting unit 1103, and a light source switching unit 105 is an eyeball. Switch the light source to be irradiated. The light source of the plurality of light sources 106 irradiates the eyeball with light, and the imaging means 107 images the reflected light from the eyeball and outputs imaging data 108. The pupil diameter calculating unit 1101 calculates the pupil diameter using a known image processing technique and outputs the calculated pupil diameter to the pupil diameter comparing unit 1102. The pupil diameter comparing means 1102 outputs the difference between the pupil diameter desired by the user and the pupil diameter output by the pupil diameter calculating means 1101 (hereinafter referred to as pupil diameter difference). The feedback light source current setting unit 1103 selects the current value of the light source according to the pupil diameter difference so that the pupil diameter difference is not more than an arbitrary threshold value, and outputs it to the light source current control unit 104.

  Using the feedback control as described above, assuming that the plurality of light sources 106 includes three light sources, the light source a, the light source b, and the light source c, first, feedback control is performed so that the pupil diameter difference at the light source a is equal to or less than a threshold value. If it is less than or equal to the threshold value, the imaging means 107 outputs the captured image data 108 to the iris part extraction means 109. Thereafter, feedback control is performed each time the light source switching unit 105 switches the light sources in the light sources b and c as well as the light source a.

Next, the iris part extraction unit 109 extracts the iris part from the imaging data 108 and outputs the iris part imaging data 110. The feature amount calculation unit 111 calculates a biometric feature amount at the time of each light source irradiation from the iris partial imaging data 110 and outputs it to the blood sugar level calculation unit 112. The blood sugar level calculating means 112 calculates the blood sugar level from the correlation table of the blood sugar level and the biometric feature amount prepared in advance in the blood sugar level correlation table 113. Details of the biometric feature amount calculation and the creation method of the blood glucose level correlation table 113 in the feature amount calculation means 111 are described in Patent Document 1.
Special Table 2003-524153 Japanese Patent Application Laid-Open No. 5-176717

  However, when switching the wavelength band of the light that is sequentially irradiated to the eyeball and using the feedback control, which is a conventional technique for making the pupil diameter constant, the feedback control is performed every time the wavelength band of the light that is sequentially irradiated is switched. It took a long time to go and make the pupil diameter constant. If the measurement time is long, the position of the eyeball, the focal position, and the line-of-sight direction are liable to occur.

  Therefore, an object of the present invention is to provide an eyeball observation apparatus that keeps the pupil diameter constant without spending time even when irradiating light with different wavelength bands to the eyeball by sequentially switching them.

  In order to solve the above-described conventional problems, the eyeball observation device of the present invention is an eyeball observation device that sequentially irradiates visible light in different emission wavelength bands to the eyeball, and observes the eyeball at that time. On the other hand, a plurality of light sources that emit visible light in different emission wavelength bands, a light source switching unit that controls turning on and off of the light sources, and sequentially switching the irradiation of the light sources, and a current that drives each of the light sources are controlled. Pupil diameter for outputting to the light source current control means a light source current control means and a current value of the other light source that makes the pupil diameter constant when the light source being turned on by the light source switching means is switched to another light source. And adjusting means.

  Further, in the eyeball observation apparatus, the pupil diameter adjusting means includes a light source table that stores in advance a relationship between illuminance and current value at the front position of the eyeball by irradiation light of each of the light sources, and each of the light sources having constant illuminance. And a light source current setting means for selecting the current value based on the light source table and outputting the current value to the light source current control means.

  Furthermore, in the eyeball observation device, an imaging means for imaging the eyeball and outputting imaging data obtained by imaging, a pupil diameter calculation means for calculating a pupil diameter from the imaging data, a desired pupil diameter and the pupil diameter calculation means, A pupil diameter comparison unit that outputs a difference between the pupil diameters to be calculated, and a current value is output to the light source current control unit so that an output of the pupil diameter comparison unit is a desired value, and an output of the pupil diameter comparison unit is When the desired value is reached, the feedback light source current setting means for outputting the current value output to the light source current control means at that time, and the current value output by the feedback light source current setting means when the desired value is reached. Current illuminance conversion means for selecting a corresponding illuminance from the light source table and outputting the selected illuminance to the light source current setting means, wherein the current illuminance conversion means controls the illuminance to the light source current control. After outputting the stage, the light source switching means sequentially switches the light source is obtained by said observing the eye.

  Further, in the eyeball observation device, the light source current setting unit selects a current value corresponding to an illuminance equal to or higher than an illuminance at which pupil diameter reduction is saturated from the light source table, and outputs the current value to the light source current control unit. Is.

  Further, in the eyeball observation apparatus, an imaging unit that images the eyeball and outputs imaging data obtained by imaging, a pupil diameter calculation unit that calculates a pupil diameter from the imaging data, and currents of different magnitudes that drive the light source Calibration light source current setting means for sequentially outputting values, the pupil diameter adjusting means, the pupil diameter calculated by the pupil diameter calculating means, and the calibration light source current control means to the light source current control means. A calibration table that stores the current value of the light source in association with each other and a light source current setting that selects a current value of each light source for an arbitrary pupil diameter based on the calibration table and outputs the current value to the light source current control unit And the light source switching means is prepared by creating the calibration table for each subject in advance. When the light source is sequentially switched, the eyeball is observed by selecting and irradiating a current value with a pupil size of a specific size for each light source.

  Furthermore, in the eyeball observation device, a pupil diameter comparing means for outputting a difference between a desired pupil diameter and a pupil diameter calculated by the pupil diameter calculating means, and a current value so that the output of the pupil diameter comparing means becomes a desired value. Feedback light source current setting means for outputting to the light source current control means, and outputting the current value outputted to the light source current control means at that time when the output of the pupil diameter comparison means reaches a desired value; A pupil diameter corresponding to the current value output from the feedback light source current setting means at the time point is selected from the calibration table, and further includes a current pupil diameter conversion means for output to the light source current setting means. After the pupil diameter conversion means outputs the pupil diameter to the light source current control means, the light source switching means sequentially switches the light sources and observes the eyeball. It is intended.

  Further, the eyeball observation device further comprises: a pupil diameter that saturates the pupil diameter reduction from the calibration table; and a saturation pupil diameter calculation means that outputs the pupil diameter to the light source current setting means. The current value of each light source for an arbitrary pupil diameter equal to or smaller than the pupil diameter output by the saturated pupil diameter calculation means is selected based on the calibration table, and is output to the light source current control means. is there.

  Furthermore, in the eyeball observation device, the light source switching means turns on one of the light sources after the light source current setting means outputs a current value to the light source current control means, and then sequentially switches the light sources, It is characterized by observing the eyeball at that time.

  Furthermore, in the eyeball observation device, one or more invisible light sources that irradiate the eyeball with invisible light in different emission wavelength bands, invisible light source current control means for controlling the current of each invisible light source, and the invisible light source current control An invisible light source current setting means for outputting an arbitrary current value to the means, and the light source switching means controls turning on and off of the light source and the invisible light source, and sequentially turning on the light source and turning the invisible light on. The light source is turned on.

  Further, in the eyeball observation device, the light source switching means sequentially turns on the light source, and then finishes turning on the invisible light source sequentially within the latency of pupillary light reflection to finish observation of the eyeball. It is a thing.

  Further, in the eyeball observation apparatus, the light source switching means is characterized in that after the light sources are sequentially turned on, the invisible light sources are turned on sequentially within 200 milliseconds, and the eyeball observation is finished.

  Furthermore, in the eyeball observation apparatus, the light source switching means is lit only in any one of the light sources.

  Further, in the eyeball observation device, the light source switching means sets a time during which all the light sources are turned off when the light source is switched for observing the eyeball (hereinafter referred to as a switching off time) to a time when the eyeball does not feel flicker. It is characterized by that.

  Furthermore, in the eyeball observation device, the switching-off time is 17 milliseconds or less.

  As described above, according to the eyeball observation apparatus of the present invention, it is possible to keep the pupil diameter constant without taking time even when the eyeballs are sequentially switched and irradiated with light having different wavelength bands.

  Embodiments of the eyeball observation apparatus of the present invention will be described below in detail with reference to the drawings.

  The embodiment of the invention described in claims 1, 2, 4, 8, 12, 13, and 14 of the present invention will be described below with reference to FIGS. It explains using.

  FIG. 1 is a block diagram of an eyeball observation apparatus in Embodiment 1 of the present invention. 1 is different from the conventional eyeball observation apparatus of FIG. 20 in that it does not include the pupil diameter calculation means 1101, the pupil diameter comparison means 1102, and the feedback light source current setting means 1103, but further includes the pupil diameter adjustment means 101. The same points are denoted by the same reference numerals, and the description may be omitted.

  The plurality of light sources 106 includes a plurality of light sources having different emission wavelength bands. For example, the multiple light sources 106 include a light source a, a light source b, and a light source c each having a light emission wavelength band 201a, a light emission wavelength band 201b, and a light emission wavelength band 201c as shown in FIG. 2, and these light sources are housed in one package. It is arranged to irradiate light on the eyeball of the subject when the light source is turned on.

  The light source current control unit 104 controls the current of each light source based on the output from the pupil diameter adjusting unit 101. The light source current control unit 104a, the light source current control unit 104b, and the light source current control unit 104c control the currents of the light source a, the light source b, and the light source c, respectively.

  The light source switching means 105 controls the turning on and off of each light source, and switches the light irradiated to the eyeball. The iris part extraction means 109 extracts the iris part from the image data 108 by a known extraction technique. A specific example will be described below with reference to FIGS. 3 (A) and 3 (B).

  FIG. 3A shows imaging data 108 obtained by imaging the eyeball with the imaging means 107. FIG. 3B is a plot of luminance data on the X line from the imaging data 108. As described above, the luminance of the eyeball imaging data 108 decreases in the order of sclera, iris, and pupil. Z1 and Z1 'are the boundary between the pupil and the iris, and Z2 and Z2' are the boundary between the iris and the sclera. Here, a threshold value S1 is set between the luminance values b and a, and a threshold value S2 is set between the luminance values c and b. If only the data having the luminance value of the imaging data 108 of the threshold values S2 to S1 is extracted, the iris partial imaging data 110 obtained by extracting the iris part from the imaging data 108 can be obtained.

  The blood glucose level correlation table 113 stores in advance the blood glucose level and the feature amount at the time of each light source irradiation. FIG. 4 shows an example of the blood glucose level correlation table 113. The correlation curve 401a, the correlation curve 401b, and the correlation curve 401c are correlation curves of blood glucose levels and feature amounts in the light source a, the light source b, and the light source c, respectively.

  The blood sugar level calculating means 112 calculates a blood sugar level from the characteristic amount at the time of each light source irradiation and the blood sugar level correlation table 113. Like the correlation curve 401a of FIG. 4, two blood glucose levels of 73 mg / dl and 125 mg / dl may be derived for one feature amount x. At this time, if the feature amount of the other correlation curve 401b is the feature amount y, 73 mg / dl is selected, and if the feature amount z is the feature amount z, 125 mg / dl is selected. Further, when there is a region where the change in the characteristic amount is small even if the blood glucose level changes as in the section n of the correlation curve 401b, the blood glucose level calculated from another correlation curve may be averaged. Thus, the blood glucose level can be specified and the accuracy can be improved by calculating the blood glucose level from a plurality of correlation curves.

  The pupil diameter adjusting means 101 selects a light source table 102 that stores the illuminance of light irradiating the eyeball and the current value of each light source, and selects a current value from the light source table 102 so that each light source has the same illuminance. A light source current setting unit 103 that outputs to the control unit 104 is provided.

  A method for creating the light source table 102 will be described in detail with reference to FIGS. 5, 6, and 7. Even though the human eye is an electromagnetic wave in the visible range and has the same energy, the brightness felt depends on the wavelength. This is because the sensitivity of the eye varies with wavelength. Therefore, a standard relative luminous sensitivity curve (standard relative luminous sensitivity curve) is determined by the CIE (Commission Internationale de l'Eclairage), and various photometric amounts are defined based on this, for example, luminous intensity and illuminance. There is something like this. FIG. 5 shows a CIE standard relative luminous efficiency curve. As shown in FIG. 5, humans feel the light with the wavelength of 555 nm brightest, and the brightness becomes harder to feel as they move away from 555 nm.

  On the other hand, the pupil diameter changes depending on the brightness perceived by humans. Therefore, in order to make the pupil diameter constant even when the light source is switched, the current of each light source may be controlled so that the brightness perceived by humans does not change even when the light source is switched. Here, when the illuminometer has illuminance in consideration of the standard relative luminous sensitivity curve described above and the illuminance to the eyeball is constant, a human may feel that the brightness is constant and the pupil diameter may be constant. it can.

  On the other hand, the brightness of a light source is often expressed by a photometric quantity called luminous intensity in a specification or the like. When the distance from the light source to the eyeball is L [m], if the light intensity of the light source is IV [cd], the illuminance E [lx] of the eyeball is expressed by the following equation.

仕様書に示されている各光源の電流に対する光度から、（数１）を用いて図６のような各光源の電流に対する照度のテーブルを作成し、光源テーブル１０２に記憶する。なお、光源テーブル１０２は、眼球を測定する前に予め作成しておく。

A table of illuminance with respect to the current of each light source as shown in FIG. 6 is created from the luminous intensity with respect to the current of each light source indicated in the specification, and stored in the light source table 102 as shown in FIG. The light source table 102 is created in advance before measuring the eyeball.

  In addition, there are cases where the light source does not emit light having a luminous intensity according to the specification because there are individual differences. Therefore, the light source table 102 may be created by measuring the light intensity and illuminance of each light source with a measuring instrument such as a photometer or illuminometer.

  The light source current setting means 103 selects a current value from the light source table 102 of FIG. 6 so that the illuminance of each light source is constant. For example, if the illuminance is 100 [lx], 14.7 [mA], 2.7 [mA], and 9.1 [mA] are selected as the current values of the light sources a, b, and c, respectively. Then, the selected current value is output to the light source current control means 104.

  Next, the operation in this embodiment will be described. First, the user creates the light source table 102 by the above-described method before measuring the eyeball. Next, the user selects the illuminance of light irradiating the eyeball (hereinafter referred to as illumination light illuminance) from the illuminance below the minimum illuminance (hereinafter referred to as minimum illuminance) among the illuminance at the maximum rated current of each light source. . In FIG. 6, assuming that the maximum rated current of all the light sources is 30 [mA], the illuminance at the maximum rated current is 165 [lx] for the light source a, 825 [lx] for the light source b, and 360 [lx] for the light source c. ]. Among these, the minimum illuminance is 165 [lx] of the light source a, and 165 [lx] is the minimum illuminance. The user selects an illuminance of 165 [lx] or less, which is the minimum illuminance, as the irradiation light illuminance. Here, it is assumed that 100 [lx] is selected as the illuminance of irradiation light.

  Next, the light source current setting unit 103 selects the current value of each light source from the light source table 102 based on the irradiation light illuminance selected by the user, and outputs it to the light source current control unit 104. In FIG. 6, the current value of each light source at an irradiation light illuminance of 100 [lx] is 14.7 [mA] for the light source a, 2.7 [mA] for the light source b, and 9.1 [mA] for the light source c. .

  Next, the light source current control unit 104 controls the current value of each light source to the value output by the light source current setting unit 103.

  Next, a plurality of light sources 106 are turned on to move to an imaging period in which the eyeball is imaged. FIG. 7 shows an example of a time chart in which the light source switching means 105 switches each light source. As shown in FIG. 7, the light source switching unit 105 is lit in the order of the light source a, the light source b, and the light source c from T1 to T2, T3 to T4, and T5 to T6, respectively. Preferably, only one light source is lit during the imaging period. This is because if two or more light sources are turned on simultaneously, the illuminance of the eyeball changes and the pupil diameter changes. Further, the time during which all the light sources are turned off (hereinafter referred to as “switching-off time”), such as the time from T2 to T3 and T4 to T5 in FIG. Generally, humans do not feel flicker if the light blinks at 60 Hz or higher. Therefore, the switching off time is preferably set to 17 milliseconds or less.

  In general, when a human irradiates light to the eyeball, the pupil diameter behaves as shown in FIG. When the eyeball is irradiated with light at time 0, the time until the TA when the pupil starts to contract is about 0.2 to 0.5 seconds, and from TA to TB when the pupil diameter reaches a minimum. Is 0.3 to 2 seconds. Here, if the light from the light source is irradiated at the timing as shown in FIG. 7, the pupil diameter fluctuates as shown in FIG. 8 immediately after T1. In order to solve this, as shown in FIG. 9, any one light source among the plurality of light sources 106 is lit in advance before T <b> 1 entering the imaging period. In FIG. 9, the light source a is turned on in advance, and the time from T0 to T1 is equal to or longer than TB until the pupil diameter reaches the minimum in FIG. 8, and preferably 2 seconds or longer.

  Next, when each light source is turned on, the imaging unit 107 images the eyeball and generates imaging data 108. Here, imaging data a, imaging data b, and imaging data c are generated for light source a, light source b, and light source c, respectively, and the imaging period ends.

  When the imaging period ends, the iris extraction unit 109 extracts the iris part from the imaging data a, the imaging data b, and the imaging data c, and the iris part imaging data a, the iris part imaging data b, and the iris part imaging data c. Is generated.

The feature amount calculation unit 111 calculates a feature amount a, a feature amount b, and a feature amount c from the iris partial imaging data a, the iris partial imaging data b, and the iris partial imaging data c.
The blood sugar level calculating unit 112 calculates a blood sugar level from the feature amount a, the feature amount b, the feature amount c, and the blood glucose level correlation table 113.

  As described above, when illuminating the eyeball with light from multiple light sources with different emission wavelength bands, the light source to be turned on is switched by setting the current value for driving the light source so that the illuminance to the eyeball is constant. However, the pupil diameter can be made constant, and it is not necessary to perform imaging repeatedly every time the light source is switched as in the conventional feedback control, so that the time can be shortened.

  Further, the light source current setting means 103 may select and output the current value of each light source at an illuminance equal to or greater than the illuminance at which the pupil diameter is saturated. In this embodiment, the pupil diameter with respect to illuminance changes as shown in FIG. Here, saturation means that the slope of the graph in FIG. When the inclination is small, fluctuations in the illuminance of the light source due to fluctuations in current and temperature greatly affect fluctuations in the pupil diameter. On the other hand, when the inclination is large, even if the illuminance of the light source varies, the variation of the pupil diameter can be small. In other words, when the inclination is large, the accuracy of the current of the light source may be low, and current control can be easily performed. Further, the threshold of inclination varies depending on the accuracy of the pupil diameter required by the apparatus and the magnitude of illuminance variation due to variations in the current and temperature of the light source, but in this embodiment, it is sufficient that the inclination is −0.005 or more. , When the illuminance is 152 [lx] or more.

  As described above, when the light source current setting means 103 selects and outputs the current value of each light source at an illuminance equal to or higher than the illuminance at which the pupil diameter is saturated, fluctuations in the pupil diameter can be further reduced.

  An embodiment of the invention described in claim 3 of the present invention will be described below with reference to FIG.

  FIG. 11 is a block diagram of an eyeball observation apparatus in Embodiment 2 of the present invention. The difference from the first embodiment is that it further includes a pupil diameter calculating unit 1101, a pupil diameter comparing unit 1102, a feedback light source current setting unit 1103, and a current illuminance conversion unit 1104, and a pupil diameter desired by the user by feedback control before the imaging period. Then, the image is picked up in the same manner as in the first embodiment.

  It is known that the pupil diameter changes depending on the condition of the subject at that time, and also changes, for example, when the emotional excitement or thought muscle movement is performed. Therefore, by performing feedback control before the imaging period, it is possible to match the pupil diameter desired by the user, and even if the subject's condition changes, measurement is performed with the same pupil diameter as the previous measurement. Can do.

  In FIG. 11, the pupil diameter calculation unit 1101 calculates the pupil diameter of the imaging data 108 output by the imaging unit 107. The pupil diameter can be calculated by a known image processing technique. For example, binarization is performed using S2 as a threshold value in FIG. Then, the pupil portion has a luminance value of 0, and the others have a luminance value of 255, for example. Then, when the area of the luminance value 0 is obtained, it becomes the area of the pupil portion, and the pupil diameter can be calculated from the area.

  The pupil diameter comparing means 1102 compares the pupil diameter output from the pupil diameter calculating means 1101 with the pupil diameter desired by the user, and outputs the difference (hereinafter referred to as pupil diameter difference).

  The feedback light source current setting means 1103 determines the current value of the light source current control means 104 that is output so that the pupil diameter difference output from the pupil diameter comparison means 1102 is equal to or less than an arbitrary threshold value. For example, a proportional / integral operation (hereinafter referred to as a PI operation) that combines a proportional operation in which the output is proportional to the input and an integral operation that works to make the integral value per unit time of the input zero with a known feedback control technique. Here, the input is the pupil diameter difference and the output is the current value of the light source. In this way, when the pupil diameter difference is equal to or less than an arbitrary threshold value, the current value of the light source at that time is output to the current illuminance conversion means 1104.

  The current illuminance conversion unit 1104 obtains the illuminance for the current value output from the feedback light source current setting unit 1103 from the light source table 102 and outputs the illuminance to the light source current setting unit 103.

  The light source current setting unit 103 selects the current value of each light source with respect to the illuminance output from the current illuminance conversion unit 1104 from the light source table 102, and outputs it to the light source current control unit 104.

  Next, the operation in this embodiment will be described. First, as in the first embodiment, the user creates the light source table 102 before measuring the eyeball. Next, a feedback control period for controlling the pupil diameter to the pupil diameter desired by the user is entered. Any light source may be lit during the feedback control period. For example, the light source a is lit here.

  First, the feedback light source current setting unit 1103 outputs an arbitrary current value of the light source a to the light source current control unit 104a. The light source current control unit 104a controls the current value output from the feedback light source current setting unit 1103, and the light source switching unit 105 turns on the light source a. The imaging means 107 images the eyeball at that time and outputs imaging data 108.

  Next, the pupil diameter calculation unit 1101 calculates the pupil diameter from the imaging data 108, obtains the pupil diameter difference, and outputs it.

  The feedback light source current setting means 1103 calculates and outputs the current value of the light source a if the pupil diameter difference is equal to or greater than the threshold value, and repeats the above operations until the difference is equal to or less than the threshold value. If it is equal to or less than the threshold value, the feedback control period ends, and the current value at that time is output to the current illuminance conversion means 1104. The current illuminance conversion means 1104 converts the current value into illuminance and outputs it to the light source current setting means 103. Subsequent operations enter the imaging period and are the same as those in the first embodiment.

  As described above, by performing feedback control in the feedback control period prior to the imaging period, it is possible to match the pupil diameter desired by the user, and even when the subject's condition changes, Measurements can be made with the same pupil diameter.

  Hereinafter, an embodiment of the invention described in claim 5 of the present invention will be described with reference to FIGS.

  The human eye has a different shape, size and response to light, and the behavior of the pupil diameter is also different. For example, the relative visibility curve shown in FIG. 5 is a standard human curve, and the curve varies from person to person. Therefore, when the current value of the light source is calculated using the standard relative luminous efficiency curve as in the first embodiment, the pupil diameter may not be constant due to the difference between the standard specific luminous efficiency curve and the subject specific luminous efficiency curve. .

  On the other hand, regarding the light intensity of the light source, the light intensity written in the specification is generally a standard light intensity, and actually has individual differences. Accordingly, the pupil diameter may vary depending on individual differences in the light intensity of the light source.

In order to solve such a problem, the third embodiment uses a table of pupil diameter and light source current instead of a table of illuminance and light source current as in the light source table 102 of the first embodiment.
FIG. 12 is a block diagram of an eyeball observation apparatus in Embodiment 3 of the present invention. The difference from the first embodiment is that a pupil diameter calculating unit 1101 and a calibration light source current setting unit 1203 are further provided, and the light source table 102 in FIG. The pupil diameter calculation unit 1101 is the same as that in the second embodiment.

  The calibration light source current setting unit 1203 outputs the current value of the light source to the light source current control unit 104 and the calibration table 1202 when the calibration table 1202 is created. The calibration table 1202 measures and stores in advance the current value for driving each light source and the pupil diameter at that time. A method for creating the calibration table 1202 will be described below.

  First, the calibration light source current setting unit 1203 sets the current value of the light source a to 2 [mA] and outputs the current value to the light source current control unit 104a. The light source current control means 104a controls the current value to 2 [mA], and the light source switching means 105 turns on the light source a. The imaging means 107 images the eyeball, and the pupil diameter calculation means 1101 calculates the pupil diameter from the imaging data 108 and outputs it to the calibration table 1202. The calibration table 1202 stores the current value output from the calibration light source current setting unit 1203 and the pupil diameter output from the pupil diameter calculation unit 1101 in association with each other.

  The calibration light source current setting unit 1203 performs the above operation while increasing the current value by 2 [mA] from 0 [mA] to the maximum rated current value, for example. The same applies to the other light sources b and c. In this way, the calibration table 1202 shown in FIG. 13 can be created.

The light source current setting unit 1201 selects the current value of each light source corresponding to the pupil diameter desired by the user from the calibration table 1202 and outputs it to the light source current control unit 104.
Next, the operation in this embodiment will be described. First, the calibration table 1202 is created as described above. Next, the user adjusts the pupil diameter from all the light sources, and in FIG. 13, from the pupil diameter 3.6 [mm] at the maximum rated current 30 [mA] of the light source a to the maximum pupil diameter 6.7 [mm]. ], The desired pupil diameter is selected. Here, when 4.0 [mm] is selected, the light source current setting unit 1201 selects the current value of each light source corresponding to the pupil diameter 4.0 [mm] from the calibration table 1202. In FIG. 13, the current values corresponding to the pupil diameter of 4.0 [mm] are 20.2 [mA] for the light source a, 2.8 [mA] for the light source b, and 11.8 [mA] for the light source c. . Then, these current values are output to the light source current control means 104. Subsequent operations are the same as those in the first embodiment.

  As described above, the pupil diameter with respect to the current of each light source is measured in advance, stored as the calibration table 1202, and the current value of each light source is set so that the pupil diameter is equal based on the calibration table 1202. Thus, it is possible to deal with individual differences in the behavior of the pupil diameter, the pupil diameter can be made constant with higher accuracy, and the pupil diameter desired by the user can be adjusted.

  An embodiment of the invention described in claim 6 of the present invention will be described below with reference to FIG.

  FIG. 14 is a block diagram of an eyeball observation apparatus in Embodiment 4 of the present invention. The difference from the third embodiment is that a pupil diameter calculating means 1101, a pupil diameter comparing means 1102, a feedback light source current setting means 1103, and a current pupil diameter converting means 1401 are further provided, and the second and third embodiments are combined. It is a thing. The pupil diameter calculating means 1101, the pupil diameter comparing means 1102, and the feedback light source current setting means 1103 are the same as those in the second embodiment.

  The current pupil diameter conversion means 1401 obtains the pupil diameter corresponding to the current value output from the feedback light source current setting means 1103 from the calibration table 1202 and outputs it to the light source current setting means 1201.

  Next, the operation in this embodiment will be described. First, a calibration table 1202 is created as in the third embodiment.

Next, a feedback control period is entered, and feedback control is performed as in the second embodiment. At this time, the pupil diameter desired by the user is set to Lx [mm].
When the feedback control period ends, the current pupil diameter conversion means 1401 obtains the pupil diameter corresponding to the current value output from the feedback light source current setting means 1103 from the calibration table 1202, and outputs 1201 to the light source current setting means. If this output pupil diameter is Ly [mm], Lx and Ly do not necessarily match. This is because the pupil diameter changes depending on the condition of the subject at that time, and also changes when, for example, emotions are excited or thought muscle movement is performed. Therefore, there is no problem even if Lx and Ly do not coincide with each other. Rather, it is possible to cope with a change in pupil diameter depending on the condition of the subject at that time. Next, the imaging period starts, but the subsequent operation is the same as in the third embodiment.

  As described above, in addition to the calibration table 1202 in which the pupil diameter and the current value of the light source are measured in advance, by using feedback control before the imaging period, it is possible to match the pupil diameter desired by the user and It is possible to cope with fluctuations in the pupil diameter depending on the condition of the person.

  The embodiment of the invention described in claim 7 of the present invention will be described below with reference to FIGS. FIG. 15 is a block diagram of an eyeball observation apparatus in Embodiment 5 of the present invention. The difference from the third embodiment is that a saturation pupil diameter calculation means 1501 is further provided.

  The saturation pupil diameter calculation means 1501 obtains the pupil diameter (hereinafter referred to as saturation pupil diameter) for each light source when the pupil diameter reduction is saturated from the calibration table 1202. Details will be described below.

  The human pupil diameter generally varies from about 2 [mm] to 8 [mm]. When the current of the light source is increased, the pupil diameter is reduced, and the reduction width when the current is gradually increased is reduced. When the light from the light source is brighter than in the first embodiment, for example, the calibration table 1202 may be as shown in FIG. At this time, the saturated pupil diameter calculating means 1501 first differentiates the graph of FIG. 16 to obtain the inclination. Then, an arbitrary threshold value with a certain inclination, for example, a saturated pupil diameter of −0.1 is calculated, and the saturated pupil region is defined as the saturated pupil diameter. Then, the saturation pupil diameter is output to the light source current setting means 1201.

  Next, the operation in this embodiment will be described. First, a calibration table 1202 is created as in the third embodiment. When the creation of the calibration table 1202 is completed, the saturated pupil diameter calculating unit 1501 calculates the saturated pupil diameter and outputs it to the light source current setting unit 1201. Next, the light source current setting means 1201 selects from the calibration table 1202 a current value equal to or greater than the current value corresponding to the saturation pupil diameter of each light source (hereinafter referred to as the saturation pupil current value), and outputs it to the light source current control means 104. To do. In FIG. 16, the saturation pupil current values are 20.3 [mA] for the light source a, 8.8 [mA] for the light source b, and 14.0 [mA] for the light source c, respectively.

  Next, the imaging period starts, but the subsequent operation is the same as in the third embodiment. Here, the pupil diameter when each light source is changed from the saturated pupil current value to the rated current value is 2.41 to 2.22 [mm] for the light source a and 2.48 to 2.20 [mm] for the light source b. The light source c is 2.52 to 2.25 [mm]. That is, the pupil diameter that can be changed in the present embodiment is 2.52 to 2.20 [mm], and may vary by 0.32 [mm] during the imaging period. However, in the case where the variation of 0.32 [mm] is in an allowable range and does not affect the blood glucose level measurement result, the light source current control unit 104 can make each light source equal to or greater than the saturation pupil current value by doing the above. The pupil diameter can be easily made constant because the current value may be low and the accuracy may be low.

  In addition, in FIG. 16, when the inclination is large, when the inclination is small, the influence on the fluctuation of the pupil diameter due to the fluctuation of the current of the light source becomes large. Accordingly, the light source current control means 104 outputs a current value in a region with a large inclination. For details, the saturation pupil diameter calculation means 1501 calculates the saturation pupil diameter of each light source, selects the minimum saturation pupil diameter (hereinafter referred to as the minimum saturation pupil diameter), and outputs it to the light source current control means 104. May be. Then, the light source current control means 104 selects from the calibration table 1202 and outputs the current value of each light source for a pupil diameter equal to or smaller than the minimum saturation pupil diameter.

  As described above, the pupil diameter can be made more constant by controlling the pupil diameter with a large inclination.

  Hereinafter, embodiments of the invention described in claims 9, 10, and 11 of the present invention will be described with reference to FIGS. 17 and 18.

  In the first to fifth embodiments, the plurality of light sources 105 includes a plurality of visible light sources. However, as described in Patent Document 1, changes in biological features due to blood sugar levels have been observed not only in visible light but also in near infrared light. Therefore, measurement may be performed using near-infrared light, and the pupil diameter needs to be controlled to be constant even when the plurality of light sources 105 include invisible light such as near-infrared light.

  FIG. 17 is a block diagram of an eyeball observation apparatus in Embodiment 6 of the present invention. The difference from the first embodiment is that an invisible light source current setting unit 1701 and an invisible light source current control unit 1702 are further provided.

  In FIG. 17, a plurality of light sources 106 includes a light source a, a light source b, and a light source c as in the first embodiment, and further includes an invisible light source a having an emission wavelength band of invisible light. The invisible light source current setting unit 1701 outputs a current value equal to or lower than the maximum rated current value of the invisible light source a arbitrarily selected by the user to the invisible light source current control unit 1702. The invisible light source current control unit 1702 controls the current of the invisible light source to the current value output by the invisible light source current setting unit 1701. The invisible light source current control unit 1702a controls the current of the invisible light source a. The light source switching unit 105 controls turning on and off of the light source including the invisible light source.

  Next, the operation in this embodiment will be described. First, the light source table 102 is created as in the first embodiment, and the light source current setting unit 103 obtains the current value of each light source corresponding to the illuminance selected by the user, and outputs it to the light source current control unit 104.

  Next, the invisible light source current setting unit 1701 outputs the current value of the invisible light source to the invisible light source current control unit 1702. The light source current control unit 104 and the invisible light source current control unit 1702 control the current of each light source.

  Next, the imaging period starts. By the way, the change of the pupil diameter from the time when the irradiation is finished from the state in which the eyeball is irradiated with light is generally as shown in FIG. Irradiation is terminated at time 0, the pupil diameter does not change until TA, and the pupil diameter gradually increases from TA and reaches a maximum at TB. Generally, TA is about 0.2 to 0.5 seconds, and this time is called latency. The time from TA to TB is about 12 seconds to 2 minutes.

  A time chart of the light source switching means 105 is shown in FIG. As illustrated in FIG. 19, the light source switching unit 105 switches the light source a, the light source b, and the light source c in the same manner as in the first embodiment, and the imaging unit 107 captures an image. The invisible light source is turned on last. Preferably, the light source switching means 105 turns on the invisible light source a and the imaging means 107 finishes imaging during the latency of about 0.2 to 0.5 seconds when the rear pupil diameter of T6 changes when the light source c is turned off.

  In this way, when the invisible light source is turned on during the latent time and the imaging is completed, the imaging can be performed with the same pupil diameter as when the visible light source is turned on. Further, after turning on the invisible light source, the pupil diameter changes as shown in FIG. 18, and when the visible light source is turned on again, it changes as shown in FIG. Assume that the lighting order of the light sources is a visible light source a, an invisible light source a, a visible light source b, and a visible light source c. Then, the pupil diameter changes as described above after turning on the invisible light source a, and it takes time to return to the pupil diameter when the visible light source a is turned on again even if the visible light source b is turned on. Therefore, the invisible light source is preferably turned on last. When the imaging period ends, the process is the same as in the first embodiment.

  As described above, the invisible light source is turned on last, and preferably by performing lighting and imaging until the pupil diameter starts to be enlarged, the pupil diameter can be set without taking time even when the plurality of light sources 106 include invisible light sources. Can be constant.

  The eyeball observation device according to the present invention can make the pupil diameter constant without taking time when sequentially irradiating light of different emission wavelength bands to the eyeball. Useful for observation.

1 is a block diagram of an eyeball observation apparatus according to Embodiment 1 of the present invention. The figure which shows the light emission wavelength spectrum of each light source of the several light source 106 in Example 1 of this invention. Sectional drawing of the imaging data 108 and the imaging data 108 in Example 1 of this invention The figure which shows the blood glucose level correlation table 113 in Example 1 of this invention. The figure which shows the standard specific luminous efficiency curve of CIE The figure which shows the light source table 102 in Example 1 of this invention. The time chart which the light source switching means 105 in Example 1 of this invention switches each light source Diagram showing changes in pupil diameter when the eyeball is irradiated with light The time chart which the light source switching means 105 in Example 1 of this invention switches each light source The graph which shows the relationship between the illumination intensity and pupil diameter in Example 1 of this invention Block diagram of an eyeball observation apparatus in Embodiment 2 of the present invention The block diagram of the eyeball observation apparatus in Example 3 of this invention The figure which shows the calibration table 1202 in Example 3 of this invention. Block diagram of an eyeball observation apparatus in Embodiment 4 of the present invention Block diagram of an eyeball observation apparatus in Embodiment 5 of the present invention The figure which shows the calibration table 1202 in Example 5 of this invention. Block diagram of an eyeball observation apparatus in Embodiment 6 of the present invention The figure which showed the change of the pupil diameter after finishing the irradiation of the light to the eyeball Time chart in which the light source switching means 105 in the sixth embodiment of the present invention switches each light source Block diagram of a conventional eyeball observation device

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Pupil diameter adjustment means 102 Light source table 103 Light source current setting means 104 Light source current control means 104a Light source current control means 104b Light source current control means 104c Light source current control means 105 Light source switching means 106 Multiple light sources 107 Imaging means 108 Imaging data 109 Iris part extraction Means 110 Iris partial imaging data 111 Feature amount calculation means 112 Blood glucose level calculation means 113 Blood glucose level correlation table 201a Emission wavelength band 201b Emission wavelength band 201c Emission wavelength band 401a Correlation curve 401b Correlation curve 401c Correlation curve 1101 Pupil diameter calculation means 1102 Pupil diameter Comparison means 1103 Feedback light source current setting means 1104 Current illuminance conversion means 1201 Light source current setting means 1202 Calibration table 1203 Calibration light source power Setting means 1401 current pupil diameter conversion unit 1501 saturated pupil diameter calculating means 1701 invisible light source current setting unit 1702 invisible light source current control means 1702a invisible light source current control means

Claims (14)

An eyeball observation device that sequentially irradiates visible light of different emission wavelength bands to the eyeball and observes the eyeball at that time,
A plurality of light sources that irradiate visible light in different emission wavelength bands to the eyeball;
Light source switching means for controlling turning on and off of the light source and sequentially switching the irradiation of the light source;
Light source current control means for controlling a current for driving each of the light sources;
Pupil diameter adjusting means for outputting to the light source current control means the current value of the other light source that has a constant pupil diameter when the light source switching means is switched to another light source.
An eyeball observation device characterized by comprising: The pupil diameter adjusting means includes
A light source table for storing in advance the relationship between the current value for driving each light source and the illuminance at the front position of the eyeball;
A light source current setting unit that selects a current value of each of the light sources that has a constant illuminance when the light source is switched based on the light source table, and outputs the light source current control unit;
The eyeball observation device according to claim 1, further comprising: Imaging means for imaging an eyeball and outputting imaging data obtained by imaging;
Pupil diameter calculating means for calculating the pupil diameter from the imaging data;
A pupil diameter comparing means for outputting a difference between a desired pupil diameter and a pupil diameter calculated by the pupil diameter calculating means;
The current value is output to the light source current control means so that the output of the pupil diameter comparison means becomes a desired value. When the output of the pupil diameter comparison means reaches the desired value, the current value is supplied to the light source current control means. Feedback light source current setting means for outputting the output current value;
Current illuminance conversion means for selecting from the light source table the illuminance corresponding to the current value output by the feedback light source current setting means when the desired value is reached, and outputting to the light source current setting means,
Further comprising
The eyeball observation apparatus according to claim 2, wherein after the current illuminance conversion means outputs illuminance to the light source current control means, the light source switching means sequentially switches the light sources to observe the eyeball. The said light source current setting means selects the electric current value corresponding to the illumination intensity more than the illumination intensity which the reduction | decrease of a pupil diameter saturates from the said light source table, and outputs it to the said light source current control means. Eye observation device. Imaging means for imaging an eyeball and outputting imaging data obtained by imaging;
Pupil diameter calculating means for calculating the pupil diameter from the imaging data;
Calibration light source current setting means for sequentially outputting different current values for driving the light source;
Further comprising
The pupil diameter adjusting means is:
A calibration table that stores the pupil diameter calculated by the pupil diameter calculating unit and the current value of the light source output to the light source current control unit by the calibration light source current control unit in association with each other;
A light source current setting means for selecting a current value of each light source for an arbitrary pupil diameter based on the calibration table and outputting to the light source current control means;
With
After creating the calibration table for each subject in advance, when the light source switching means sequentially switches the light sources, the current value of each light source is selected so as to have an arbitrary pupil diameter, and the eyeball is irradiated to perform irradiation. Observing the
The eyeball observation device according to claim 1. A pupil diameter comparing means for outputting a difference between a desired pupil diameter and a pupil diameter calculated by the pupil diameter calculating means;
The current value is output to the light source current control means so that the output of the pupil diameter comparison means becomes a desired value, and when the output of the pupil diameter comparison means reaches a desired value, the current value is output to the light source current control means at that time Feedback light source current setting means for outputting the measured current value;
A pupil diameter corresponding to the current value output by the feedback light source current setting means when the desired value is reached, is selected from the calibration table, and current pupil diameter conversion means is output to the light source current setting means;
Further comprising
6. The eyeball observation apparatus according to claim 5, wherein after the current pupil diameter conversion means outputs the pupil diameter to the light source current control means, the light source switching means sequentially switches the light sources to observe the eyeball. . Calculating a pupil diameter at which pupil diameter reduction is saturated from the calibration table, and outputting to the light source current setting means;
Further comprising
The light source current setting unit selects a current value of each light source for an arbitrary pupil diameter equal to or smaller than the pupil diameter output from the saturation pupil diameter calculation unit based on the calibration table, and outputs the current value to the light source current control unit. ,
The eyeball observation device according to claim 5, wherein: The light source switching means turns on one of the light sources after the light source current setting means outputs a current value to the light source current control means, and then sequentially switches the light sources to observe the eyeball at that time The eyeball observation device according to claim 2, wherein the eyeball observation device is provided. One or more invisible light sources that irradiate the eyeball with invisible light in different emission wavelength bands;
Invisible light source current control means for controlling the current of each invisible light source;
An invisible light source current setting means for outputting an arbitrary current value to the invisible light source current control means;
Further comprising
6. The eyeball according to claim 2, wherein the light source switching unit controls turning on and off of the light source and the invisible light source, and turns on the invisible light source after sequentially turning on the light source. Observation device. The light source switching means sequentially turns on the invisible light source within the latency of pupillary light reflection after sequentially turning on the light source,
The eyeball observation device according to claim 9, wherein the eyeball observation is finished. The light source switching means sequentially turns on the invisible light source within 200 milliseconds after sequentially turning on the light sources,
The eyeball observation apparatus according to claim 10, wherein the eyeball observation is finished. 6. The eyeball observing device according to claim 2, wherein only one of the light sources is turned on by the light source switching unit. The light source switching means sets a time during which all the light sources are turned off at the time of switching the light source for observing an eyeball (hereinafter referred to as a switching off time) to a time during which the eyeball does not feel flickering,
The eyeball observation device according to claim 2 or 5, characterized by the above. The eyeball observation device according to claim 13, wherein the switching off time is 17 milliseconds or less.

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