JPH04232467A - Apparatus and method for measuring blood sugar - Google Patents

Abstract

PURPOSE: To provide an apparatus and method for measuring blood sugar to minimize the blood sugar value measurement error. CONSTITUTION: The apparatus for measuring blood sugar comprises a microcomputer, a key unit for inputting a signal for starting the measurement to the microcomputer, a light source selector for selecting green or red light source under the control of the microcomputer, a light emitting unit for emitting a light to a blood sugar test sheet via a light emitting diode selected by the selector, a light regulator for regulating the intensity of the light emitted from the emitting unit to the sheet constant, a reflected light detector for detecting the reflected light from the sheet, an amplifier for amplifying an inducted current for the reflected light, an analog-digital converter for converting the analog data amplified by the amplifier into digital data to input it to the microcomputer, and a display unit for displaying the blood sugar value converted by the microcomputer.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a blood sugar measuring device for measuring blood sugar level, which selectively uses a plurality of light emitting diodes to measure blood sugar level to minimize measurement errors. It is related to the measurement method.

0002

[Prior art] As a conventional blood sugar measuring device,
There is a portable blood glucose measuring device disclosed in Publication No. 9-14843,
This portable blood glucose measuring device is formed as shown in FIG.
0, a calculation unit 20 that includes an AD converter 70 and a microcomputer and calculates a blood sugar level based on the output signal of the blood sugar level detection unit 10, an alarm buzzer 40, and a blood sugar level display 3.
0, and the blood sugar level detection section 10 and calculation section 20 are configured to be worn on the body. Since the blood glucose level detecting section 10 includes the blood glucose level measuring electrode 50 that is inserted into the body, the burden on the patient is reduced, so that it can be used continuously for a long time.
This has the advantage of making it more compact and portable, but on the other hand, the measurement electrodes may be damaged or the blood circulation may be abnormal depending on the patient's physical condition, so the measurement results may not be accurate. The disadvantage was that it was inaccurate.

[0003] In addition, in order to measure the amount of blood sugar, a method that is somewhat more advanced than the well-known test strip method for clinical chemistry tests is to emit light onto a blood glucose test strip that changes color depending on the blood glucose concentration. Electronic automatic blood glucose meters are used that measure blood sugar levels by detecting the intensity of light reflected from test strips. However, the above-mentioned test strip method and electronic automatic blood glucose meter used for blood glucose measurement check the light reflectance of the blood glucose test strip depending on the wavelength of the light source that reacts with the light of the blood glucose test strip, as shown in Figure 6. As a result, the wavelength of the light from the light source was 700 nm (n
= 1 x 10-9 (m)), that is, 700 x 10-9 [m
] Band (red band) is dense and decomposition due to each concentration is reduced, but on the other hand, the wavelength of light is 500 to 60.
In the 0 [nm] band (green-yellow band), the measurement bands are relatively evenly spaced and generally widely distributed, so it is easy to use, but the blood sugar measurement results are relatively inaccurate. was there.

0004

[Problems to be Solved by the Invention] Based on these characteristics, we used a red light emitting diode and a green light emitting diode as light sources for blood sugar measurement, and measured the optical sensor induced current depending on the blood sugar concentration. The results are shown in FIG. As described above, when a green light emitting diode is used, the photosensor induced current, which decreases as the blood sugar concentration increases, shows a relatively smooth curve with a small rate of change. On the other hand, when a red light emitting diode is used, the photosensor induced current, which decreases as the blood sugar concentration increases, has a large rate of change and exhibits a relatively steep curve. Therefore, as a result, the resolution ability in the low concentration area is good, but saturation phenomenon occurs in the high concentration area, so if the red and green light emitting diodes are used indiscriminately, the measurement itself is difficult. In addition, there is a problem in that a considerable amount of measurement error occurs due to this.

The present invention was developed in view of the various problems mentioned above, and is controlled by a microcomputer. When the blood sugar concentration is low, a red light emitting diode is used to measure it, and when the blood sugar concentration is high, it is measured using a red light emitting diode. It is an object of the present invention to provide a blood glucose measuring device and a blood glucose measuring method that minimize measurement errors by measuring using green light emitting diodes.

[0006]

Means for Solving the Problems In order to achieve the above object, the blood glucose measuring device of the present invention as set forth in claim 1 is a blood glucose measuring device for measuring blood sugar level, which includes a microcomputer and a computer for starting measurement. a key unit for inputting a signal to the microcomputer; a light source selection unit for selecting a green or red light source under the control of the microcomputer; and a light emitting diode selected by the light source selection unit to emit light to the blood sugar test strip. a light emitting section, a light adjustment section that adjusts to a constant intensity of light emitted from the light emitting section to the blood sugar test strip, a reflected light detection section that detects reflected light reflected from the blood sugar test strip, and the detection section. an amplifying section that amplifies the induced current in response to the reflected light; an analog/digital converting section that converts the analog data amplified by the amplifying section into digital data and inputs the digital data to a microcomputer; 1. A blood glucose measuring device comprising: a display section that displays a value.

[0007] Furthermore, the blood glucose measuring device according to the present invention as set forth in claim 2 is characterized in that the light emitting section always emits a constant amount of light to the blood glucose test strip using a comparator of the light adjusting section.

Further, in the blood glucose measuring device of the present invention as set forth in claim 3, the comparator has a non-inverting input terminal connected to a variable resistor for variable adjustment to keep the intensity of light emitted from the light emitting portion constant. characterized in that it is configured to adjust.

Further, in the blood glucose measuring device of the present invention as set forth in claim 4, the amplifying section includes a digital converting section that amplifies the induced current for the reflected light detected by the photodiode using an operational amplifier, and a photodiode. It is characterized in that it is input to the adjustment section.

[0010] Furthermore, the blood glucose measuring method of the present invention as set forth in claim 5 is a first blood glucose concentration method in which the blood glucose concentration is measured by emitting light onto a blood glucose test paper whose color is changed depending on the blood glucose concentration and using the reflected light. a measurement step, a light source replacement step of determining whether the blood sugar concentration is high or low from the measurement value of the first blood sugar concentration measurement step, and determining whether or not the light source replacement is appropriate; a second blood sugar concentration measurement step of measuring blood sugar concentration using a light source, a blood sugar level conversion step of converting the data measured in the second blood sugar concentration measurement step into a blood sugar level, and displaying the converted blood sugar level. and a blood sugar level display step.

The blood glucose measuring device of the present invention according to claim 6 is characterized in that in the light source changing step, the light source is replaced by one of a plurality of light emitting diodes each having a different color. shall be.

[0012] Furthermore, the blood glucose measuring device of the present invention according to claim 7 is characterized in that the intensity of the light emitted from the plurality of light emitting diodes is adjusted to a constant level by a light adjustment section. .

[0013] Furthermore, in the blood sugar measuring device of the present invention as set forth in claim 8, in the blood sugar conversion step, the measured value is converted by a microcomputer and displayed on the display unit.

[0014]

[Operation] According to the blood glucose measuring device and blood glucose measuring method of the present invention, a light source is selected using a plurality of light emitting diodes, and then the blood glucose concentration of the blood glucose test strip is measured by the light source, thereby eliminating measurement errors. Blood sugar levels can be measured with compensation.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a graph showing the measurement error rate with respect to blood sugar concentration when measuring blood sugar using a green light emitting diode and a red light emitting diode applied to the present invention, and FIG. 3 is a detailed circuit diagram of FIG. 2, and FIG. 4 is a flowchart showing the operation sequence of the blood glucose measuring method of the present invention.

In FIG. 1, when a red light emitting diode is used, relatively fewer errors occur overall than when a red light emitting diode is used;
When looking at the center point (P) as a reference, the measurement error rate is lower in low concentration areas than when using green light emitting diodes, but the measurement error rate is lower in high concentration areas than when using green light emitting diodes. It can be seen that the ratio is large. That is, the red light emitting diode has a small measurement error rate in a low concentration area, and the green light emitting diode has a small measurement error rate in a high concentration area, and the present invention utilizes these characteristics.

In FIGS. 2 and 3, reference numeral 1 denotes a microcomputer, which has two output terminals S1 and S2. Reference numeral 2 denotes a light source selection section, and the output terminal S1 of the microcomputer 1 has a resistor. One side of the resistor R1 is connected to the base of the transistor TR1, the other side of the resistor R1 is connected to the base of the transistor TR1, one side of the resistor R2 is connected to the output terminal S2 of the microcomputer 1, and the other side of the resistor R2 is connected to the base of the transistor TR2. A low level signal is connected to the base of each transistor TR from each of the output terminals S1 and S2.
1, it operates when input to TR2.

Reference numeral 3 denotes a light emitting unit which emits red or green light to the blood sugar test strip upon application of a signal by the light source selection unit 2, and the positive (+) terminal of the green light emitting diode LED1 is connected to the collector of the transistor TR1. , the positive terminal of the red light emitting diode LED2 is connected to the collector of the transistor TR2, and the transistors TR1 and TR2 are operated by the voltage VCC1 to emit light.
It emits green or red light onto blood sugar test strips.

Reference numeral 4 denotes a reflected light detecting section for detecting the reflected light emitted by the light emitting section 3 onto the blood sugar test strip, and the reference numeral 5 denotes a reflected light detecting section which detects the reflected light of the light emitted onto the blood sugar test strip by the light emitting section 3, and is composed of a photodiode PD1. The positive terminal of the photodiode PD1 that constitutes the reflected light detection section 4 is connected to the non-inverting input terminal (+) of the operational amplifier OP1, and the negative terminal of the photodiode PD1 is connected to the non-inverting input terminal (+) of the operational amplifier OP1. is connected to the connection point between the resistor R6 and the capacitor C2, and is connected to the inverting input terminal (-) of the operational amplifier OP1, so that it is inverted and amplified by the resistor R6 and the capacitor C2.

Reference numeral 6 denotes a light adjusting section that adjusts the intensity of light emitted from the light emitting section 3 to the blood sugar test strip to a constant level based on the voltage inverted and amplified by the amplifying section 5; The output terminal of the operational amplifier OP1 constituting 5 is connected to the resistor R.
4. It is connected to the point where R5, variable resistor VR1, and the negative terminal of Zener diode ZD1 are connected, and the other side of resistor R5 is connected to the inverting input terminal (-) of comparator COM1.
The operational amplifier OP1 output is input, and the comparator C
A non-inverting input terminal (+) of OM1 is connected to a variable resistor VR1 so that the resistance value can be changed appropriately as necessary.

Further, the connection point to which one side of the output terminal capacitor C1 of the comparator COM1 is connected is connected to the transistor T.
The transistor TR3 is connected to the base of the comparator COM1, and is turned on or off according to the output of the comparator COM1, so that the amount of light emitted from the light emitting diodes LED1 and LED2 is maintained constant.

Reference numeral 8 is a key unit for inputting a signal to the microcomputer 1 to start blood sugar measurement, and reference numeral 9 is a display that displays the blood sugar level determined by the microcomputer 1 so that the user can confirm it. Department.

Next, the operation of this embodiment will be explained.

The blood glucose measuring device according to the present invention configured as described above has an output terminal S1 of the microcomputer 1.
If a low level signal is sent through the resistor R1, this signal is applied to the transistor TR1 through the resistor R1.

As the transistor TR1 operates, the light emitting diode LED1 connected to the collector of the transistor TR1 is operated to emit green light to the blood sugar test strip.

Then, the reflected light of the green light emitted to the blood sugar test paper is detected by the photodiode PD1 of the reflected light detection section 4.
After detecting it and converting it into a current, it is input to the inverting input terminal (-) and the non-inverting input terminal (+) of the operational amplifier OP1.

Accordingly, the operational amplifier OP1 connects the photodiode P using the resistor R6 and the capacitor C2.
The reflected light data detected by D1 is inverted and amplified, and the inverted and amplified value is input to an analog/digital converter 7 to be converted into digital data.

The digital data is input to the microcomputer 1 and compared with a reference program for determining blood sugar concentration.

On the other hand, if the intensity of the light emitted by the light emitting section 3 is inputted to the inverting input terminal (-) of the comparator COM1 through the resistor R5 of the light adjusting section 6, it is kept constant by the Zener diode ZD1 through the resistor R4. Since it is compared with the reference voltage VCC2 input to the non-inverting input terminal (+) of the comparator OP2 while maintaining the voltage, the output value of the operational amplifier OP1 input to the inverting input terminal (-) at this time becomes non-invert. If it is higher than the reference voltage VCC2 input to the input terminal (+), adjust the variable resistor VR1 so that the reference voltage of the non-inverting input terminal (+) becomes higher.
By activating the high level signal to the transistor TR3, the amount of light emitted from the light emitting diode LED1 to the blood sugar test strip becomes constant.

On the other hand, the inverting input terminal (-
) is input to the non-inverting input terminal (+
) is lower than the reference voltage input to
By sending out the high level signal without adjusting the variable resistor VR1 to operate the transistor TR3, the amount of light emitted to the blood sugar test strip by the light emitting diode LED1 is made constant.

Next, when the light source is replaced and a low level signal is sent out through the output terminal S2 of the microcomputer 1, this signal is applied to the transistor TR2 through the resistor R2.

Accordingly, the operation of the transistor TR2 causes the light emitting diode connected to the collector of the transistor TR2 to be operated to emit red light to the blood glucose test strip.

Thereafter, the reflected light reflected by the blood sugar test strip is received from the photodiode PD1, the value is converted into a current, and the value is inputted to the operational amplifier OP1, and the value is inputted to the resistor R6.
and capacitor C2 to invert and amplify the value, input the amplified value to the inverting input terminal (-) of comparator COM1, and similarly to the case where the light emitting diode LED1 emits green light to the blood sugar test strip. , and a reference voltage input to the non-inverting input terminal (+), and adjusts the variable resistor VR1 appropriately based on the comparison result so that the light emitting diode LED2 always emits a constant amount of light.

Next, FIG. 4 will be explained.

First, when power is supplied to the blood glucose meter of the present invention, in step S1, the microcomputer 1
The initialization operation is performed and all the circuit operation parts are brought to the initial state.

Next, in step S2, it is determined by the key unit 8 whether the measurement switch for measuring blood sugar is ON, and if the measurement switch is not ON (N
In the case of O), it is continuously determined whether the measurement switch is turned on while maintaining the non-measurement mode, and if the measurement switch is turned on in step S2 (in the case of YES), the process proceeds to step S3. Then, under the control of the microcomputer 1, the display section 9 displays that the preparation for measurement has been completed.

[0038] Next, in step S4, blood whose blood glucose concentration is to be measured is dropped onto the blood glucose test paper, and in step S5, it is determined whether the measurement start switch is turned on, and it is determined whether the measurement start switch is not turned on. Case (in case of NO)
To do this, continuously determine whether the measurement start switch is turned on,
When the measurement start switch is turned on (in case of YES)
In step S6, the microcomputer 1 starts subtracting the reference measurement time (the time that should elapse in order to measure the blood glucose concentration of the blood dropped onto the blood glucose test strip) that has been input in advance to the microcomputer 1.

If the reference measurement time starts to be subtracted and a certain reaction time (the time for blood sugar to react to the blood sugar test strip at low and high concentrations) has elapsed in step S7 (YES).
), the process proceeds to step S8, where a warning sound to ``remove the dropped blood from the blood glucose test strip'' is generated through the buzzer, so that the person taking the test removes the blood, and in step S7, a certain response is detected. If the time has not elapsed (NO), it is determined whether the reaction time has elapsed continuously.

[0040] Subsequently, in step S9, step S
It is determined whether the reference measurement time started in step 6 has been completed, and if the subtraction has been completed (in the case of YES), the process proceeds to step S10, and the output terminal S of the microcomputer 1 is
1 through the green light emitting diode LED 1 of the light source selection section 2
is operated, and while the emitted light is maintained constant by the light control unit 6, green light is emitted onto the blood sugar test paper, which has changed color according to the blood sugar concentration.

[0041] Next, in step S11, the reflected light of the green light emitted by the green light emitting diode LED1 is detected by the reflected light detecting section 5, and the current induced by the detected reflected light is applied to the amplifying section 6. After amplifying it to a certain level, inputting it to the analog/digital converter 7,
Proceeding to step S12, the data is compared with reference data for determining blood sugar concentration that has been input into the microcomputer 1 in advance.

If the blood sugar concentration determined in step S12 is low (in the case of YES), as shown in FIG. 1, the measurement error rate of the green light emitting diode LED1 is higher than that of the red light emitting diode LED2. Since the measurement error rate is large, the process proceeds to step S13, where the microcomputer 1 sends a high level signal through the output terminal S1 to turn off the light emitting diode LED1, and sends a low level signal through the output terminal S1 to turn off the red light emitting diode. LED
2 makes the blood sugar test strip emit red light.

Thereafter, in step S14, the light reflected from the blood sugar test strip is detected by the reflected light detection section 5, and the induced current due to the reflected light is amplified to a constant level by the amplification section 6, and the amplified analog signal is If the signal is converted into a digital signal by the analog/digital converter 7 and input to the microcomputer 1, in step S15, the microcomputer 1 calculates an accurate blood sugar level using a blood sugar level conversion program using reflected light that has been input in advance. Then, the converted blood sugar level is displayed on the display section 9 by the microcomputer 1 in step S15.

On the other hand, as a result of analyzing the measured value of the reflected light with respect to the light emitted from the green light emitting diode LED1 to the blood sugar test paper in step S12, it is found that the concentration is not low (No.
), it is determined that the blood sugar concentration is high or high, so there is no need to replace the light emitting diode, and the process directly proceeds to step S15 where the microcomputer 1 converts the blood sugar level into a numerical value indicating the blood sugar level. The converted blood sugar level is displayed on the display section 9.

It should be noted that the present invention is not limited to the above embodiments, and can be modified as necessary.

[0046]

Effects of the Invention As described above, according to the blood sugar measuring device and blood sugar measuring method of the present invention, by appropriately selecting and using a light emitting diode with a low measurement error rate according to the blood sugar concentration, measurement errors can be minimized and accuracy can be achieved. Not only can it provide accurate measured values, but it can also be used not only as a blood glucose meter, but also as a urine sugar meter and a protein meter, and has considerable economical effects.

[Brief explanation of the drawing]

[Fig. 1] A graph showing the measurement error rate for blood sugar concentration when blood sugar is measured using a green light-emitting diode and a red light-emitting diode applied to the present invention.

[Fig. 2] Block diagram of the blood sugar measuring device of the present invention

[Figure 3] Detailed circuit diagram of Figure 2

FIG. 4 is a flowchart showing the operation sequence of the blood sugar measuring method of the present invention.

[Figure 5] Block diagram of a conventional blood sugar measuring device

[Figure 6] Graph showing the light reflectance of blood glucose test strips depending on the wavelength of the light source after the reaction of conventional blood glucose test strips to light.

[Fig. 7] Graph showing changes in photosensor-induced current with respect to blood sugar concentration when measuring blood sugar using conventional green light-emitting diodes and red light-emitting diodes.

[Explanation of symbols]

1 Microcomputer 2 Light source selection section 3 Light emitting part 4 Reflected light detection section 5 Amplification section 6. Light adjustment section 7 Analog/digital conversion section 8 Key part 9 Display section

Claims (8)

[Claims] 1. A blood sugar measuring device for measuring blood sugar level, comprising: a microcomputer; a key unit for inputting a signal to the microcomputer to start measurement; and a green or red light source selected under control of the microcomputer. a light source selection section for emitting light onto the blood sugar test paper through the light emitting diode selected by the light source selection section; and a light emitting section for emitting light onto the blood sugar test paper from the light emitting section to a constant level. an adjustment section, a reflected light detection section that detects the reflected light reflected from the blood sugar test strip, and an amplification section that amplifies the induced current for the detected reflected light;
It is characterized by comprising an analog/digital conversion section that converts the analog data amplified by the amplification section into digital data and inputs it to a microcomputer, and a display section that displays the blood sugar level converted by the microcomputer. Blood sugar measuring device. 2. The blood glucose measuring device according to claim 1, wherein the light emitting section always emits a constant amount of light to the blood glucose test strip using a comparator of a light adjusting section. 3. The comparator is configured to connect a variable resistance for variable adjustment to a non-inverting input terminal so as to adjust the intensity of light emitted from the light emitting part to a constant value. Item 2. Blood sugar measuring device according to item 2. 4. The amplifying section inputs the induced current caused by the reflected light detected by the photodiode to a digital converting section and a light adjusting section, which are amplified using an operational amplifier. The blood sugar measuring device described. 5. A first blood sugar concentration measuring step of emitting light to a blood sugar test paper whose color has changed depending on the blood sugar concentration and measuring the blood sugar concentration using the reflected light; and a measurement of the first blood sugar concentration measuring step. a light source replacement step of determining whether the blood sugar concentration is high or low based on the value and determining whether or not to replace the light source; and a second blood sugar concentration measurement that measures the blood sugar concentration using the light source replaced based on the measured value of the first blood sugar concentration measurement step. step, a blood sugar level conversion step for converting the data measured in the second blood sugar concentration measuring step into a blood sugar level, and a blood sugar level display step for displaying the converted blood sugar level. Measuring method. 6. The blood glucose measuring method according to claim 5, wherein in the light source changing step, the light source is changed to one of a plurality of light emitting diodes each having a different color. 7. The blood glucose measuring method according to claim 6, wherein the intensity of the light emitted from each of the plurality of light emitting diodes is adjusted to be constant by a light adjustment section. 8. The blood sugar measuring method according to claim 5, wherein in the blood sugar conversion step, the measured value is converted by a microcomputer and displayed on a display unit.