JP2001204693A - Water transpiration measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water transpiration measuring instrument which measures water transpiration from the surface of the skin of a human body by a ventilation capsule method, can objectively discriminate the stabilization of a base line or measured value, and can shorten the measuring time. SOLUTION: In the water transpiration measuring instrument 1A, a control and arithmetic unit 8A discriminates that the output values f(ti) (where, i=1, 2,..., n) of the instrument 1A with respect to a humidity sensor 4 when sampling is made n times at prescribed time intervals Δt from an arbitrary point of time t0 after measurement is started are stable when the relation |f(ti)-f(ti-1)|<=a is met between the output values f(ti) and a reference output value (a) with respect to the range of fluctuation at stable time and a visual or aural displaying means displays the discriminated result.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a moisture transpiration measuring device for measuring the amount of moisture transpiration from the skin surface by a ventilation capsule method, wherein the moisture transpiration amount for automatically determining the steady-state value of the output of a humidity sensor. It relates to a measuring device.

[0002]

2. Description of the Related Art When examining the sweating function clinically, or examining the amount of water evaporating from the skin or the surface of the eyes to evaluate the properties of the skin or examining the effects of moisturizing agents on the skin,
Alternatively, the amount of water evaporating from the skin surface (including mucous membranes) is measured when examining the dryness of the eyes.

[0003] One of the methods of measuring the amount of water evaporation is to cover a capsule provided with a humidity sensor inside on a measurement site of the skin, and to output the humidity sensor when a carrier gas having a predetermined humidity flows into the capsule. And a ventilating capsule method for determining the amount of water transpiration from the skin surface based on the difference between the humidity sensor output in a blank test and the humidity test.

As shown in FIG. 4, an apparatus 1 for measuring the amount of water transpiration generally includes a gas supply source 2 such as a gas cylinder filled with dry air, and a carrier supplied from the gas supply source 2 to the capsule 5. A flow meter 3 for adjusting the flow rate of gas, a capsule 5 having a humidity sensor 4 such as a quartz oscillator type humidity sensor therein, an oscillator 6 connected to the humidity sensor 4, a frequency counter 7 connected to a succeeding stage, and an arithmetic unit It consists of eight. The capsule 5 has a gas inlet 9, and the carrier gas flowing into the capsule 5 from the gas inlet 9 flows from the side wall of the capsule 5 toward the center of the measurement site of the skin S as shown by an arrow A. Send out. In addition, a shutter 10 is provided on the installation surface of the capsule 5 on the skin S. An output display device such as a monitor 11, a printer 12, and a pen recorder is connected to the arithmetic unit 8.

[0005] When measuring the amount of moisture evaporation of the skin S with the moisture evaporation amount measuring device 1, the capsule 5 is applied to the skin S, and the carrier gas is caused to flow into the capsule 5 with the shutter 10 closed and the oscillator 6 is operated. Oscillation frequency is set to frequency counter 7
Measure with Next, the shutter 10 is opened, a carrier gas is caused to flow into the capsule 5 in the same manner, and the oscillation frequency of the oscillator 6 is counted. In this case, the opening of the shutter 10 causes the carrier gas in the capsule 5 to contain moisture B evaporated from the skin S. On the other hand, the output of the humidity sensor 4 changes the oscillation frequency from the oscillator 6, so that the shutter The oscillation frequency of the oscillator 6 after the opening of the shutter 10 is different from the oscillation frequency of the shutter 10 before the opening. Therefore, when the oscillation frequency from the start of the measurement is counted by the frequency counter 7, a relationship between time and frequency can be obtained as shown in FIG. Arithmetic unit 8
Is the difference between the frequencies before and after the opening of the shutter 10 (that is,
Based on the magnitude of the (frequency shift), the amount of water loss is calculated.

[0006]

When determining the amount of water transpiration from the skin S by the water transpiration measuring device 1 shown in FIG. 4, the actual measurement operation of the measurer includes the relationship between the time and the frequency shown in FIG. Observe the figure with a monitor, pen recorder, etc.
A steady value (base line) of the frequency before the opening of 0 is found, and the frequency F ₀ (Hz) is obtained by the arithmetic unit 8. Next, the shutter 10 is opened, and the relationship between time and frequency is monitored again. Then, a steady value of the frequency after the shutter 10 is opened is found, the frequency F ₁ (Hz) is obtained by the arithmetic unit 8, and the shutter 10 is closed. Then, based on the difference between the frequency F ₀ (Hz) and the frequency F ₁ (Hz), the amount of water loss calculated by the arithmetic unit 8 is obtained.

However, the frequency F ₀ (Hz) serving as a baseline before the opening of the shutter 10 and the shutter 10
The selection of the steady-state value F ₁ (Hz) of the frequency after the opening is left to the subjectivity of the measurer, so that the magnitude of the frequency shift may vary from measurer to measurer and lacks objective reliability of the measurement. There is a problem.

In addition, a frequency F ₀ (Hz) as a baseline before the shutter opening and a frequency F ₁ (Hz) stable after the shutter opening are obtained by measuring on a recording paper of a pen recorder. However, according to this method, immediately after the measurement operation on the skin S is completed, the frequency F ₀ (Hz) serving as the baseline before the shutter is opened.
Also, a stable value F ₁ (Hz) of the frequency after the shutter is opened cannot be obtained, and the measurement time is long.

[0009] For such a problem, the present invention provides a water evaporation quantity measuring device of water loss is measured by the ventilation capsule method from the skin surface, steady-state value as a shutter opening before baseline (frequency F ₀ (Hz)) and a steady value (frequency F ₁ (Hz)) related to the humidity sensor after opening the shutter.
The objective of the present invention is to obtain the measurement objectively without depending on the measurer's arbitrary judgment, and to shorten the measurement time.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a capsule having a humidity sensor inside and an opening at a lower end thereof, the opening of which is closed by a shutter, and the carrier gas being supplied to the capsule. The control arithmetic unit detects the difference between the output from the humidity sensor at the time of flowing the water and the output from the humidity sensor when the carrier gas flows into the capsule at the opening of the capsule. Is a moisture transpiration rate measuring apparatus of the ventilation capsule method for calculating the moisture transpiration rate of the humidity sensor, wherein an output value of the humidity sensor at an arbitrary time point t ₀ after the start of measurement is f (t ₀ ), and a predetermined time interval from t ₀ Δt
The output value of the humidity sensor when sampling n times for each time is f (t _i ) (where i = 1, 2,..., N)
When the reference output value relating to the fluctuation range at the time of stability is a,
The control arithmetic unit: (a) at each sampling

[0011]

When | f (t _i ) −f (t _i−1 ) | ≦ a is satisfied, or (b) the straight line of the output value f (t _i ) at the time of sampling n times by the least square method Expression

[0012]

When f (t) = bt + c (where b and c are coefficients), at each sampling time

[0013]

[6] │f (t _i) - when the _{(bt i + c) │ ≦} a is satisfied, it is determined that the output of the humidity sensor is taken constant value, the judgment of the processing device, visual A target or auditory display means provides a moisture transpiration measuring device that indicates that the output of the humidity sensor has a steady value.

Further, in such a moisture evaporation amount measuring apparatus, a shutter is provided so as to be opened and closed by a control arithmetic unit, and the control arithmetic unit takes a steady value of the output of the humidity sensor with the shutter closed. It is determined whether or not the average value of the output values of the n-th sampling at this time is calculated,
Open the shutter, and then determine whether the output related to the humidity sensor has a steady value with the shutter open,
When it is determined that a steady value has been obtained, the average of the output values of the n times of sampling at this time is obtained, and the average of the output value with the shutter closed and the output value with the shutter open The present invention provides a moisture transpiration measurement device that calculates the amount of water transpiration from the skin based on the difference from the average.

According to the apparatus for measuring the amount of evaporated water of the present invention,
(A) When the reference output value a relating to the fluctuation range at the time of stability is set, a state in which the difference between the measurement value sampled i-th at a predetermined interval and the measurement value sampled before it is equal to or smaller than the reference output value a when n times, or
(B) When the deviation of the output value of each sampling in the n-times sampling and the deviation of the output value of each sampling in the n-times sampling is equal to or smaller than the reference output value a, the control arithmetic unit determines the humidity by Since it is determined that the output value of the sensor has a steady value, the steady value of the output at the time of measuring the baseline or skin can be objectively obtained without arbitrary determination by the measurer.

In addition, the apparatus for measuring the amount of evaporated water of the present invention visually or audibly displays the determination result to the measurer, and the measurer immediately confirms that the baseline has been stabilized by this display. The shutter can be opened to start measuring the skin, and after confirming from the above display that the measured value of the skin has a steady value, the shutter can be immediately closed to end the measuring operation. Therefore, waste of the measurement time can be omitted, and the measurement time can be shortened.

Further, in this moisture evaporation measuring device, when the control arithmetic unit determines a baseline or a steady value at the time of measurement, the opening and closing of the shutter and the calculation of the moisture evaporation are automatically performed in accordance with the determination. When the measurement is performed, the measurement can be completed more easily in a short time.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. In each of the drawings, the same reference numerals represent the same or equivalent components.

FIG. 1 is a block diagram of one embodiment of the apparatus for measuring the amount of evaporated water according to the present invention. The moisture evaporation amount measuring apparatus 1A includes a gas cylinder filled with dry air, a gas supply source 2 such as an air pump, a flow meter 3 for adjusting a flow rate of a carrier gas supplied from the gas supply source 2 to the capsule 5, and a crystal inside. A capsule 5 having a humidity sensor 4 such as a vibrator-type humidity sensor and a shutter 10 on an installation surface on the skin S; an oscillator 6 connected to the humidity sensor 4; a frequency counter 7 connected to the subsequent stage; The output device comprises a monitor 11, a printer 12, a pen recorder and the like connected to the control arithmetic unit 8A. The carrier gas flowing from the gas inlet 9 of the capsule 5
Is similar to the conventional moisture transpiration measuring apparatus 1 in FIG. 4 in that the water is transmitted from the side wall of the skin S toward the center of the measurement site of the skin S as indicated by an arrow A.

Therefore, when the oscillation frequency of the oscillator 6 that changes according to the output of the humidity sensor 4 is counted by the frequency counter 7, a relationship between time and frequency is obtained as shown in FIG.

In the moisture evaporation amount measuring apparatus 1A, the oscillation frequency of the oscillator 6 at an arbitrary time point t ₀ after the start of the measurement is represented by f
(T ₀ ), and the output value of the humidity sensor when sampling is performed n times at predetermined time intervals Δt from t ₀ is represented by f
(T _i ) (where i = 1, 2,..., N), and when the reference output value relating to the fluctuation width at the time of stability is a,

[0022]

When | f (t _i ) −f (t _i−1 ) | ≦ a is satisfied, the control arithmetic unit 8A determines that the oscillation frequency of the oscillator 6 has a steady value, and this determination is made. Is notified to the measurer by a visual display such as a display on the monitor 11 or emission of an arbitrary signal lamp, or by an audible display such as emitting a predetermined sound.

More specifically, when the measurement is started with the shutter 10 closed, the control arithmetic unit 8A samples the frequency counted by the frequency counter 7 at predetermined time intervals Δt immediately after the start of the measurement. When the frequency f ₀ (t _i ) at the time of sampling is compared with the frequency f ₀ (t _i-1 ) at the time of the previous sampling, and the difference is equal to or smaller than the reference output value a for n times. Then, it is determined that the baseline is stable and has a steady value.

Even after the shutter 10 is opened and the water B evaporated from the skin S is contained in the carrier gas in the capsule 5, the control arithmetic unit 8A keeps the frequency counter 7 at a predetermined time interval Δt. Is sampled, and the frequency f ₁ (t _i ) at a certain sampling point and the frequency f _{1 at} the previous sampling point are sampled.
₁ (t _i-1 ), and if the difference is less than or equal to the reference output value a for n times, it is determined that the frequency has a steady value.

As shown in FIG. 3, when a drift is observed in the relationship diagram between time and frequency, a straight-line equation by the least squares method is obtained from each frequency f (t _i ) at the time of sampling n times.

[0026]

F (t) = bt + c (where b and c are coefficients)

[0027]

Equation 9] │f (t _i) - when the _{(bt i + c) │ ≦} a is satisfied, the frequency is determined that the control arithmetic unit 8A taking the constant value, a visual or audible that effect Is notified to the measurer.

More specifically, when the measurement is started in a state where the shutter 10 is closed, the control arithmetic unit 8A calculates a straight line formula by the least square method from each frequency f ₀ (t _i ) at the time of sampling n times.

[0029]

[Mathematical formula-see original document] f ₀ (t) = b ₀ t + c ₀ (where b ₀ and c ₀ are coefficients)

[0030]

When | f ₀ (t _i ) − (b ₀ t _i + c ₀ ) | ≦ a is satisfied, it is determined that the baseline is stable.

Even after the shutter 10 is opened and the moisture B evaporated from the skin S is contained in the carrier gas in the capsule 5, the control arithmetic unit 8A continues to operate the frequency counter 7 every predetermined time interval Δt. Sample the frequency counted by

[0032]

F ₁ (t) = b ₁ t + c ₁ (where b ₁ and c ₁ are coefficients), and at each of n samplings

[0033]

When | f ₁ (t _i ) − (b ₁ t _i + c ₁ ) | ≦ a is satisfied, it is determined that the frequency is stable and has a steady value.

Therefore, after the measurer knows the stability of the baseline by means of a monitor display or the like, the shutter 1 is quickly released.
The measurement may be performed on the carrier gas containing the moisture B evaporated from the skin S by opening the opening 0. After the shutter 10 is opened, the measurement may be terminated after the stability of the frequency is known by a monitor display or the like. I just need. Therefore, the measurer does not need to wait more than necessary for the stability of the baseline or the frequency, and the entire measurement time can be reduced.

Here, the reference output value a relating to the fluctuation width at the time of stabilization is determined by the required measurement accuracy, measurement temperature, measurement area,
It can be appropriately determined according to the response of the humidity sensor, the flow rate of the carrier gas, and the like. That is, ΔH (%) indicates a change in relative humidity due to water evaporation from the skin S and ρ indicates a saturated water vapor amount at the measurement temperature, which is obtained based on the output of the humidity sensor 4.
(G / m ³ ), the flow rate of the carrier gas is V (m ³ / hr),
Assuming that the measurement area is A (m ² ), the amount of water evaporation J (g / m ² · hr) from the skin is

[0036]

## EQU14 ## J = ΔH · ρV / A · 100 Here, assuming that the response of the humidity sensor 4 to the relative humidity change ΔH is k (Hz /% RH) and the frequency change by the humidity sensor 4 is ΔF,

[0037]

Since ΔH = ΔF / k, the water loss J is

[0038]

J = ΔF · ρV / A · k · 100 Therefore, when the accuracy required for measuring the amount of water evaporation is X (g / m ² · hr),

[0039]

Since X = a · ρV / A · k · 100, the reference output value a regarding the fluctuation range at the time of stability is:

[0040]

A = X · A · k · 100 / ρV

The amount of water transpiration J from the skin is generally 1 to 5
0 (g / m ² · hr). For example, if the required measurement accuracy X is 0.5 (g / m ² · hr),
The reference output value a is

[0042]

[Mathematical formula-see original document] a = 0.5 · A · k · 100 / ρV Here, when the measurement temperature is 20 ° C., the saturated water vapor amount ρ
Is 17.3 (g / m ³ ), and the flow rate V of the carrier gas is 0.
015 (m ³ / hr), measuring area A is 0.0003
(M ² ), the response k of the humidity sensor 4 is set to 20 (Hz /% R).
H)

[0043]

A = 0.5 × 0.0003 × 20 × 100 / (17.3 × 0.015) = 1.1 (Hz)

The longer the time taken to judge whether or not the frequency has a stable steady value, the longer the reliability of the judgment is. In the determination of whether the measured value of the carrier gas containing the water B evaporated from the skin S has a steady value, the time taken for one determination is preferably 200 seconds or less, and 10 seconds or less. Is preferred.
The sampling interval Δt is preferably set to 0.05 to 100 seconds, and the sampling number n is preferably set to 1 to 2000.

The moisture evaporation amount measuring apparatus 1A not only informs the measurer of whether or not the measured value of the carrier gas containing the moisture B evaporated from the baseline or the skin S has a steady value, but also informs the measurer of the monitor display or the like. The control operation unit 8A controls the measurement operation performed by the measurer after the measured value of the carrier gas containing the water B evaporated from the baseline or the skin S takes a steady value, and is automatically performed. It is preferable to do so. For example, shutter 1
After the measurement is started with 0 closed, if the control arithmetic unit 8A determines that the baseline has a steady value, the control arithmetic unit 8A promptly sends a control signal for opening the shutter 10 to the shutter. Then, the measurement is continued for the carrier gas containing the water B evaporated from the skin S, and the stability of the frequency counted by the frequency counter 7 is determined. When the control arithmetic unit 8A determines that the frequency is stable, the control arithmetic unit 8A immediately sends a control signal for closing the shutter 10 to the shutter 10, and terminates the measurement.

The control arithmetic unit 8A includes a shutter 10
The average of the frequencies related to n samplings when the control arithmetic unit 8A determines that the baseline has a steady value before the opening of the shutter 10 and the frequency after the shutter 10 is opened When the control arithmetic unit 8A determines that a steady value is taken, the average of the frequencies pertaining to n times of sampling is obtained, and the amount of water evaporation from the skin S is automatically calculated based on the difference between these averages. Preferably.

Thus, it is possible to more easily and accurately measure the amount of water transpiration from the skin S.

Although the present invention has been described based on the moisture transpiration measuring device 1A shown in FIG. 1, the present invention can take various other forms. For example, as the humidity sensor 4, an electrostatic capacitance type humidity sensor, a resistance type humidity sensor, or the like may be used in addition to the quartz oscillator type humidity sensor. In this case, as a measurement value based on the output from the humidity sensor, not the frequency but the stability of the capacitance or electric resistance is determined by the control arithmetic unit.

[0049]

According to the moisture evaporation amount measuring apparatus of the present invention,
When measuring the amount of water transpiration from the skin surface by the ventilation capsule method, whether or not the baseline or the measured value is a stable steady value is not determined by the operator's subjective judgment, but by the judgment of the control arithmetic unit It can be determined objectively and the reliability of the measurement can be increased. Further, after the control arithmetic unit determines that the baseline or the measured value has a steady value, the process can immediately proceed to the next measuring operation, so that the measuring time can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram of a moisture evaporation amount measuring apparatus according to the present invention.

FIG. 2 is a diagram illustrating a relationship between time and frequency.

FIG. 3 is a diagram illustrating the relationship between time and frequency.

FIG. 4 is a block diagram of a conventional apparatus for measuring the amount of evaporated water.

FIG. 5 is a relationship diagram between time and frequency.

[Description of Signs] 1A Moisture Evaporation Measurement Device 2 Gas Supply Source 3 Flow Meter 4 Humidity Sensor 5 Capsule 6 Oscillator 7 Frequency Counter 8A Control Arithmetic Device 9 Gas Inlet 10 Shutter A Arrow indicating carrier gas flowing direction B Skin Moisture evaporating from skin S skin

Claims (5)

[Claims] 1. An output from a humidity sensor when a carrier gas is introduced into a capsule having a humidity sensor provided therein and having an opening at a lower end, the opening being closed by a shutter, and the opening of the capsule. The part is applied to the skin, and based on the difference from the output from the humidity sensor when the carrier gas flows into the capsule, the control processor calculates the amount of water transpiration from the skin. The output value of the humidity sensor at an arbitrary time point t ₀ after the start of the measurement is f (t ₀ ), and a predetermined time interval Δt from t ₀
The output value of the humidity sensor when sampling n times for each time is f (t _i ) (where i = 1, 2,..., N)
When the reference output value relating to the fluctuation range at the time of stability is a,
Control arithmetic unit, (a) ## EQU1 ## During each sampling _{│f (t i) -f (t} i-1) when │ ≦ a is satisfied, or (b) n times the sampling time of the output value When the equation of a straight line by the least square method of f (t _i ) is given by f (t) = bt + c (where b and c are coefficients), at each sampling time: (t _i) - when the _{(bt i + c) │ ≦} a is satisfied, it is determined that the output of the humidity sensor is taken constant value, the judgment of the processing device, a visual or audible display means Is a moisture transpiration rate measuring device that indicates that the output of the humidity sensor has a steady value. 2. The moisture transpiration measuring device according to claim 1, wherein the reference output value a is 0.05 to 10 Hz. 3. The sampling interval Δt is 0.05 to 10.
The moisture evaporation amount measuring apparatus according to claim 1 or 2, wherein the time is 0 second. 4. The moisture transpiration rate measuring apparatus according to claim 1, wherein the number of samplings n is 1 to 2000. 5. A shutter is provided so as to be opened and closed by a control arithmetic unit. The control arithmetic unit determines whether an output related to the humidity sensor has a steady value in a state where the shutter is closed, and If you decide that
At this time, the average of the output values of the n times of sampling is calculated, the shutter is opened, and then it is determined whether or not the output related to the humidity sensor has a steady value with the shutter opened, and the steady value is determined. Is determined, the average of the output values of the n samplings at this time is obtained, and the average of the output value when the shutter is closed and the average of the output value when the shutter is opened 5. The moisture evaporation measuring device according to claim 4, wherein the moisture evaporation from the skin is calculated based on a difference between the moisture evaporation and the skin evaporation.