JPH11113858A - Infrared ray clinical thermometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an infrared ray clinical thermometer which improves the measuring accuracy without increasing the number of a calibration point. SOLUTION: This infrared ray clinical thermometer is provided with a temperature detecting part having an infrared sensor and a temperature sensor, an arithmetic part 311, a control means having a memory and a timer, an A/D converter, a display part, and a buzzer. The output value (x) of the infrared sensor is inputted in the computing element 311b of the arithmetic part 311. The output value (y) of the temperature sensor is inputted in a linearization means 311a of the arithmetic part 311, converted into 'y', and inputted into the computing element 311b. The characteristics showing the relation between the y' and the environment temperature is formed into approximately linear shape. The output values (x) of the infrared sensor, the output value y' of the linearization means 311a, and respective coefficients (a-i) and (j) read from a memory 312 are substituted for a prescribed polynomial expression f12 (x, y') so as to find the body temperature in the computing element 311b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an infrared thermometer.

[0002]

2. Description of the Related Art In recent years, as infrared technology has advanced, infrared thermometers have been widely used.

In an infrared thermometer, the intensity of infrared rays generated from a measurement site is detected by an infrared sensor, the environmental temperature is detected by a temperature sensor, and the body temperature is obtained in a short time from the output of the infrared sensor and the output of the temperature sensor. For this reason, there is a great advantage that the measurement time can be reduced as compared with a general thermometer conventionally used, and is extremely useful, for example, when measuring the body temperature of a restless infant or child. .

As a method of obtaining body temperature from the infrared sensor output and the temperature sensor output, a relation between the infrared sensor output and the temperature sensor output and the body temperature is approximated by a polynomial, and the values of the infrared sensor output and the temperature sensor output are expressed by the polynomial. To obtain the body temperature value. Hereinafter, this method will be specifically described.

The output value of the infrared sensor is represented by a parameter x,
Assuming that the output value of the temperature sensor is a parameter y, the body temperature value can be represented by a polynomial f ₁ (x, y) shown in the following (1).

F ₁ (x, y) = a ₁ x ³ + b ₁ x ² + c ₁ x + d ₁ x ² y + e ₁ xy + f ₁ xy ² + g ₁ y + h ₁ y ² + i ₁ y ³ + j ₁ (1)

Here, a _{1 to} j ₁ in the above equation (1) are constants (a _{1 to} i ₁ are coefficients). Therefore, this polynomial f ₁
If the coefficients a _{1 to} i ₁ and j _{1 of} (x, y) are known, the output value x of the infrared sensor and the output value y of the temperature sensor are substituted into the polynomial f ₁ (x, y). , Body temperature can be determined.

In this case, each of the coefficients a _{1 to} i ₁ and j ₁
Is the calibration, ie, x and y at multiple calibration points
(Data) and the target temperature value at that time are substituted in the above equation (1), and the simultaneous equations obtained by this are solved to set in advance.

However, the above equation (1) is merely an approximate equation and does not accurately represent the relationship between the values of x and y and the target temperature (the temperature of the measurement site). There is a drawback that a thermometer cannot measure body temperature with high accuracy.

Although approximation accuracy can be improved by increasing the number of calibration points, in this case, since the number of calibration points increases, calibration (the coefficients a _{1 to} i
₁ and j ₁ ) is troublesome and takes a long time.

[0011]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an infrared thermometer capable of improving measurement accuracy without increasing the number of calibration points.

[0012]

This and other objects are achieved by the present invention which is defined below as (1) to (3).

(1) It has an infrared sensor for detecting infrared rays emitted from the measurement site and a temperature sensor for detecting the environmental temperature. The signal value from the infrared sensor and the signal value from the temperature sensor are used as the signal values. In an infrared thermometer that calculates a body temperature value by substituting into an approximation polynomial with parameters as parameters, a signal value from a temperature sensor to be substituted into the approximation polynomial has a substantially linear dependence on the environmental temperature. And infrared thermometer.

(2) The temperature sensor is a thermistor, and converts a direct signal value from the thermistor so that the dependence characteristic on the environmental temperature becomes substantially linear, thereby obtaining a temperature to be substituted into the approximate polynomial. The infrared thermometer according to (1), which calculates a signal value from the sensor.

(3) The infrared ray according to the above (1) or (2), wherein the order of the approximation polynomial is second order or higher for the parameter of the signal value from the infrared sensor and the parameter of the signal value from the temperature sensor. Thermometer.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an infrared thermometer according to the present invention will be described in detail based on a preferred embodiment shown in the accompanying drawings.

FIGS. 1 and 2 are a front view and a side view, respectively, of an infrared thermometer (hereinafter simply referred to as a "thermometer") of the present invention, and FIG. 3 is a thermometer of the present invention in which a probe cover is attached to a probe. AA in FIG. 1 showing a state.
4 is a cross-sectional side view schematically showing the internal structure of the thermometer of the present invention, FIG. 5 is a perspective view showing the structure of a thermometer, and FIG. 6 is a circuit configuration example of the thermometer of the present invention. FIG. 1 and 2 are referred to as "upper", the lower side is referred to as "lower", the upper side in FIGS. 3 and 4 is referred to as "tip", and the lower side is referred to as "base".

As shown in FIGS. 1 to 4, the thermometer 1 of the present invention is an ear-type thermometer that detects body temperature by measuring the intensity of infrared rays emitted from the inside of the ear (the eardrum) and has a casing 21. The thermometer includes a thermometer main body 2, a power switch 3 and a display unit 5 installed on the front of the thermometer main body 2, and a measurement switch 4 installed on an upper rear surface of the thermometer main body 2.

The probe 6 is mounted on the front side of the thermometer main body 2 so as to be detachable from the thermometer main body 2. As shown in FIG. 3, the support 7 has a large-diameter portion 71 and a small-diameter portion 72 at the distal end thereof, and the large-diameter portion 71 and the small-diameter portion 72.
Male screws 73 and 74 are respectively formed on the outer periphery of.

On the other hand, at the base end of the tubular probe 6, there is provided a base portion 61 which comes into contact with the front end surface of the large diameter portion 71.
A female screw 62 that is screwed with the male screw 74 is formed on the inner surface on the proximal end side of the probe 6. By screwing the male screw 74 and the female screw 62, the probe 6 is supported and fixed on the support 7.

The probe 6 has a shape whose outer diameter gradually decreases toward the distal end, and the outer peripheral portion (edge) 63 of the distal end of the probe 6 is designed for safety when inserted into the ear cavity. It has a rounded shape.

At the center of the support 7, an infrared ray (heat ray) introduced from the tip of the
A light guide (waveguide) 8 leading to 01 is provided upright. The light guide 8 is preferably made of a metal such as copper having good heat conductivity, and its inner surface is plated with gold.

The light guide 8 is covered with a protective sheet 81 so as to cover the opening at the tip. This prevents dust, dust and the like from entering the light guide 8. The protective sheet 81 has infrared transmittance, and examples of the constituent material include the same resin material as the probe cover 11 described later.

A ring nut 9 is screwed into the large diameter portion 71 of the support 7. That is, a female screw 91 is formed on the base end side inner surface of the ring nut 9, and the female screw 91 is screwed with the male screw 73 of the large diameter portion 71, so that the ring nut 9 is supported on the support base 7. Fixed.

The ring nut 9 has a tapered portion 92 whose outer diameter gradually decreases from the vicinity of the distal end of the female screw 91 toward the distal end, and the inner surface of the tapered portion 92 is provided on the body 12 of the probe cover 11. An engaging portion 93 to be engaged is formed.

The probe 6 is covered with the probe cover 11,
When the ring nut 9 is attached and rotated and screwed in a predetermined direction, the body 12 of the probe cover 11 is sandwiched between the inclined portion 64 of the probe 6 and the engaging portion 93 of the ring nut 9, and the probe cover 11 is It is securely fixed to the probe 6.

A flange mounting base and the like are provided around the open end (base end) of the probe cover 11 of this embodiment,
The probe cover 11 can be fixed by sandwiching the flange or the like between the probe 6 and the ring nut 9.

Therefore, it is possible to prevent the probe cover 11 from being displaced from the probe 6 or being easily separated from the probe 6 during measurement of body temperature or the like. In order to remove the probe cover 11 from the probe 6, it is necessary to rotate the ring nut 9 with a considerable force to release the screw engagement with the large diameter portion 71. Inconvenience such as putting in the mouth is also prevented.

The distal end surface 94 of the ring nut 9 forms a substantially flat surface. When the probe 6 is inserted into the ear cavity, the distal end surface 94 abuts near the entrance of the ear cavity, and regulates the insertion depth of the probe 6 into the ear cavity to a certain depth. For this reason, it is always possible to perform measurement under appropriate conditions, it is possible to prevent a measurement error due to a variation in the insertion depth into the ear cavity, and to damage the inner part of the ear because the probe 6 enters the ear cavity too deeply. Such inconvenience does not occur.

On the outer peripheral surface of the tapered portion 92 of the ring nut 9, a plurality of grooves (slip preventing means) 95 for exerting an anti-slip effect when rotating the ring nut 9 in a tightening direction or a loosening direction are circled. They are formed at predetermined intervals in the circumferential direction. In addition, not only the concave portion such as the groove 95 but also a convex portion can exert the same function. Further, a high friction material such as rubber may be provided.

The probe cover 11 has a shape whose base end is open and whose end is closed. This probe cover 11
A cylindrical body 12 whose outer diameter and inner diameter gradually decrease toward the tip, a film 14 formed at the tip of the body 12 that can transmit infrared rays, Membrane 14
And a ring-shaped lip portion 15 protruding further to the distal end side.

The body 12, the film 14, and the lip 15 are preferably integrally formed of a resin material. Examples of the resin material include polyolefins such as polyethylene, polypropylene, and ethylene-vinyl acetate copolymer, and polyesters such as polyethylene terephthalate and polybutylene terephthalate.

In the probe cover 11, the lip 1
5 allows the membrane 14 to be
From the front end to the base end side by a predetermined distance (H).

Thus, when the probe cover 11 is attached to the probe 6 and inserted into the ear cavity, the membrane 14 touches the inner surface of the ear cavity and its peripheral portion, and the probe cover 11
Is prevented from being touched by a finger or the like at the time of attachment / detachment operation to / from the probe 6, and the surface of the film 14 can be kept clean.
Higher measurement accuracy can be maintained.

The lip 15 has a shape such that the inside thereof is fitted to the tip of the probe 6. That is, as shown in FIG. 3, when the probe cover 11 is attached to the probe 6, the lip portion 15 is fitted to the distal end outer peripheral portion 63 of the probe 6. Thus, when the probe cover 11 is inserted into the ear cavity (at the time of measurement), the tip of the probe cover 11 is
Of the film 14 is prevented.
Is stretched with a constant tension, thereby preventing the film 14 from wrinkling or sagging, thereby contributing to an improvement in measurement accuracy.

The tip of the lip 15 has a rounded shape. Thus, when inserted into the ear cavity, high safety is secured without feeling pain or damaging the inner wall of the ear cavity.

As shown in FIG. 4, a circuit board 30 is provided in the casing 21.
Is mounted with a temperature detecting section 10, a control means 31 including a microcomputer, an A / D converter 32, and a buzzer 33. A power supply unit 40 for storing a battery is provided in the casing 21.
Electric power is supplied to each part of the circuit board 30.

As shown in FIG. 6, the temperature detecting section 10 includes an infrared sensor 101 and a temperature sensor 107.

The control means 31 has a built-in arithmetic unit 311, a memory (RAM, ROM, EEPROM) 312 and a timer 313. The timer 313 includes an auto power off timer for suppressing unnecessary power consumption.

This auto power-off timer automatically turns off the power after a predetermined time (60 seconds) from the start of the timer when the power switch 3 is left in an on state. Even if the power switch 3 is turned off within 60 seconds after the start of the auto power-off timer, the timer continues its counting operation (time measurement) until 60 seconds elapse.

As shown in FIG.
Includes a thermopile (thermocouple train) 102. The hot junction 103 of the thermopile 102 is provided on the heat collecting portion 106 located on the center side via the heat insulating band 105, and the cold junction 104 is provided on the outer peripheral side of the heat insulating band 105.

The infrared sensor 101 outputs a signal corresponding to the temperature difference between the hot junction 103 and the cold junction 104.

As shown in FIG. 6, this infrared sensor 1
01 is output to the A / D converter 32
After being converted into a digital signal by the controller, the digital signal is input to the control means 31. Hereinafter, the output signal of the infrared sensor 101 converted into a digital signal by the A / D converter 32 is simply referred to as the output signal of the infrared sensor 101. The infrared sensor 101 and the A / D converter 32 constitute infrared detecting means.

As shown in FIG. 5, a temperature sensor 107 is provided near the infrared sensor 101. This temperature sensor 107 is the infrared sensor 101
Temperature on the outer peripheral side of the heat insulating zone 105, that is, the cold junction 1
In addition to detecting the temperature of 04, the temperature of the atmosphere (environmental temperature) is detected. As the temperature sensor 107, for example, a thermistor can be used.

From the temperature sensor 107, the cold junction 1
A signal corresponding to the temperature of 04 (environmental temperature) is output.

As shown in FIG. 6, this temperature sensor 10
The output signal (analog signal) 7 is converted into a digital signal by the A / D converter 32 and then input to the control means 31. Hereinafter, the output signal of the temperature sensor 107 converted into a digital signal by the A / D converter 32 is simply referred to as the output signal of the temperature sensor 107. The temperature sensor 107 and the A / D converter 32 constitute a temperature detecting means.

In such a temperature detecting section 10, a signal corresponding to the temperature difference between the hot junction 103 heated by the infrared irradiation and the cold junction 104 not irradiated with the infrared by the infrared sensor 101 and the temperature sensor 107, respectively, and the environmental temperature Is obtained, and the arithmetic unit 311 of the control means 31 described later measures the body temperature by using these functions.

FIG. 7 is a block diagram (conceptual diagram) showing a configuration example of the arithmetic unit 311 of the control means 31.

As shown in the figure, an operation unit 311 receives an output signal (direct signal) from the temperature sensor 107 and converts the value (data) into a linearizing means 311a.
And an arithmetic unit 311b for obtaining a body temperature based on the output signal from the linearization means 311a and the output signal from the infrared sensor 101.

The linearizing means 311a is connected to the temperature sensor 10
The output value (direct signal value) y of 7 is converted to y '. This conversion does not convert y to a temperature value (environmental temperature value),
The characteristic indicating the relationship between the output value (the converted value of y) y 'of the linearizing means 311a and the environmental temperature (the characteristic of the dependence of y' on the environmental temperature) is substantially linear.

In this embodiment, the linearizing means 311a converts the output value y of the temperature sensor 107 into y 'according to the following equations (2) and (3).

Z = (y−β) / β (2)

Y ′ = z / (1 + z / 2) (3)

Here, β in the above equation (2) is an output value of the temperature sensor 107 when the environmental temperature is a reference temperature (reference environmental temperature).

The reference temperature is set at a temperature substantially near the center of the environmental temperature range in which the operation of the thermometer is guaranteed. For example, if the guaranteed environmental temperature range is 5 ° C to 35 ° C,
It is set around 20 ° C. This β is set in advance by a calibration described later for each thermometer.

In this case, the following equation (4) may be used instead of the above equation (3).

Y ′ = αz / (1 + z / 2) (4)

Here, α in the above equation (4) is a constant (real number).
It is. Note that the above (3) is obtained by using the above equation (4).
This corresponds to the case where α = 1.

The arithmetic unit 311b is connected to the infrared sensor 101
Of the output value (signal value) x and the output value y 'of the linearizing means 311a are approximated by a third order (third order for each of the parameters x and y') representing the relationship between these x and y 'and the body temperature. Substituting into the polynomial f ₂ (x, y ′), that is, the following equation (5), and calculating the body temperature (the temperature of the measurement site)
Ask for.

[0060] _{f 2 (x, y') =} ax 3 + bx 2 + cx + dx 2 y'+ exy' + fxy' 2 + gy' + hy' 2 + iy' 3 + j ··· (5)

However, a, b, c, d,
e, f, g, h, and i are coefficients, respectively. The coefficients a to i and j are set in advance for each thermometer by calibration described later.

A calculation program including the above equations (2), (3) and (5) is stored in the memory 312 in advance.

Next, the output value y of the temperature sensor 107 is converted into y 'by the above equations (2) and (3), so that the characteristic indicating the relationship between the y' and the ambient temperature is substantially linear. And the function and effect of this linearization will be described.

When the temperature sensor 107 is a thermistor, the output value (direct signal value) y of the temperature sensor 107 changes according to the environmental temperature.
It corresponds to. The resistance value R of this temperature sensor 107
Is represented by the following equation (6).

R = R0 exp (B / T−B / T0) (6)

Where T in the above equation (6) is the environmental temperature, R
0 is the resistance value of the temperature sensor 107 when the environmental temperature is T0, and B is a constant.
This is called a "constant".

Here, the unit of the environmental temperatures T and T0 is [K], which is an absolute temperature value. By modifying the above equation (6), the following equation (6 ′) is obtained.

T = 1 / [{ln (R / R0) / B} + (1 / T0)] (6 ′)

From the above equation (6 '), it is found that the environmental temperature T changes along the 1 / log curve with respect to the change in the resistance value R. FIG. 12 shows a characteristic curve indicating the relationship between the environmental temperature T and the resistance value R. The scale of the environmental temperature in FIG. 12 is obtained by converting the environmental temperature into [° C.] (the value differs from [K] by about 273).

On the other hand, when the infrared sensor 101 is a thermopile, the output value x changes substantially linearly with a change in the temperature difference between the hot junction 103 and the cold junction 104.

When such a 1 / log curve and a linear sensor output characteristic coexist, it is difficult to approximate the body temperature by a polynomial such as the equation (1) described in the prior art. It is considered impossible, and therefore, the measurement accuracy of the body temperature is low.

Therefore, in the thermometer 1, as described above, the output characteristic of the 1 / log curve is substantially linearized by the linearizing means 311a.

Here, the resistance value (output value) of the temperature sensor 107 (thermistor) when the environmental temperature is the reference temperature (reference environmental temperature) TT is RR, and the resistance value R at an arbitrary temperature is
Assuming that the rate of change of the (output value) with respect to the RR is Z, the rate of change Z is expressed by the following equation (7). The following equation (7) corresponds to the above equation (2).

Z = (R−RR) / RR (7)

By substituting R in the above equation (6) into the above equation (7), the following equation (8) is obtained.

Z = exp {(B / T−B / TT)} − 1 (8)

Further, R ′ represented by the following equation (9) is defined. Note that the following equation (9) corresponds to the above equation (3). The environmental temperatures T and TT are values at absolute temperatures.

R ′ = Z / (1 + Z / 2) (9)

By substituting Z of the above equation (8) into the above equation (9), the following equation (10) is obtained.

[0080]

(Equation 1)

As shown in FIG. 8, the characteristic indicating the relationship between R 'represented by the above equation (10) and the environmental temperature T is a straight line which is approximately downward to the right. Here, as in FIG. 12, the scale of the environmental temperature is obtained by converting the environmental temperature into [° C.].

That is, in the linearizing means 311a,
According to the above equations (2) and (3), the temperature sensor 10
By converting the output value y from 7 into y '
And the characteristic indicating the relationship between the ambient temperature T and the ambient temperature T are substantially linear (substantially linear) (the 1 / log curve shown in FIG. 12 is changed to a straight line as shown in FIG. 8 by the linearizing means 311a). become).

As described above, in the thermometer 1, the output value from the temperature sensor 107 (direct signal) is set by the linearizing means 311a so that the characteristic indicating the relationship between y 'and the environmental temperature T becomes substantially linear. Value) y is converted to y ′, and the body temperature is determined using the y ′, the output value x of the infrared sensor 101, and the approximate polynomial of Expression (5).
The accuracy of measuring body temperature is improved.

The output value y of the temperature sensor 107 is
First, it is converted into a temperature value (environmental temperature) T, and the parameter X
A method of obtaining a body temperature value using an approximation polynomial of the temperature sensor 107 (thermistor) and the parameter T is also conceivable. Electrical calibration may be required. On the other hand, in the thermometer 1, since the body temperature is obtained without converting the output value y of the temperature sensor 107 into the environmental temperature T, it is not necessary to perform the thermoelectric calibration, and the labor and time are reduced. Has advantages.
That is, the productivity is good, which is advantageous for mass production.

In the thermometer 1, as described above, β in the above equation (2) and the coefficients a to i and j in the above equation (5) are used.
Is set in advance by calibration. Hereinafter, this calibration will be described.

First, β is set. In this case, the output value of the temperature sensor 107 when the environmental temperature is the reference temperature (for example, 25 ° C.) is stored in the memory 312 as β.

Next, at a plurality of calibration points, for example, at a plurality of environmental temperatures (for example, 7 ° C., 15 ° C., 25 ° C., and 35 ° C.), the temperatures of a plurality of targets (reference targets) whose temperatures are known, respectively. (For example, 32 ° C., 37 ° C., 42
C), and the output value x of the infrared sensor 101 and the output value y of the temperature sensor 107 are detected.

At this time, the output value y of the temperature sensor 107
Using the above β and the above equations (2) and (3), y ′
Y ′ and the output value x of the infrared sensor 101
And the target temperature into the above equation (5) to obtain a
Obtain simultaneous equations for ~ j. Then, a to j are obtained from the simultaneous equations by, for example, the least square method, and are stored in the memory 312. This completes the calibration.

Next, the operation of the thermometer 1 will be described.
The probe 6 is screwed and attached to the small-diameter portion 72 of the support 7 of the thermometer main body 2 as described above.
Cover the probe cover 11. Then, from above,
The ring nut 9 is inserted and screwed into the large diameter portion 71 of the support base 7. As a result, the body 12 of the probe cover 11 is sandwiched between the inclined portion 64 of the probe 6 and the engaging portion 93 of the ring nut 9, and the probe cover 11 is fixed to the probe 6. Thus, the mounting of the probe cover 11 is completed.

Next, the power switch 3 is turned on,
After a lapse of a predetermined time, the thermometer main body 2 is gripped, and the probe 6 covered with the probe cover 11 is inserted into the ear cavity.

Next, the measurement switch 4 is pressed for a predetermined time. Thereby, the measurement of the body temperature is performed. That is, the infrared rays (heat rays) emitted from the inside of the ear (the eardrum) sequentially pass through the membrane 14 and the protective sheet 81, are introduced into the light guide 8, and are repeatedly reflected on the inner surface thereof to repeat the reflection on the infrared sensor 101 of the temperature measuring unit 10. And irradiates the heat collecting section 106.

As shown in FIG.
The output value x of the calculation unit 311 of the calculation unit 311 of the control means 31
11b.

On the other hand, the output value y of the temperature sensor 107 is
The data is input to the linearizing means 311a of the calculating unit 311 of the control means 31. In this linearizing means 311a, the output value y of the temperature sensor 107 and β read from the memory 312
Is used to perform arithmetic processing. That is, the temperature sensor 1
By substituting the output value y of 07 and β read from the memory 312 into the above equations (2) and (3), y ′ is obtained, and the y ′ is output. The output value y 'of the linearizing means 311a is input to the calculator 311b.

In the arithmetic unit 311b, the infrared sensor 10
1 and the output value y ′ of the linearizing means 311a,
The arithmetic processing is performed using the coefficients a to i and j read from the memory 312. That is, the infrared sensor 1
01 and the output value y 'of the linearizing means 311a.
And the coefficients a to i and j read from the memory 312 are substituted into the above equation (5) to determine the body temperature.

[0095] The obtained body temperature is displayed on the display unit 5. When the measurement of the body temperature is completed, the buzzer 33 sounds to notify the user of the measurement. By the notification of this buzzer 33,
The operator pulls out the probe 6 from the ear cavity.

[0096]

EXAMPLES Next, specific examples of the thermometer of the present invention will be described.

The above-mentioned thermometer 1 of the present invention is calibrated to obtain β in the above equation (2) and each coefficient a in the above equation (5).
~ I and j were set. The conditions of this calibration are as follows: the environmental temperatures are 7 ° C., 15 ° C., 25 ° C., and 35 ° C. For these four environmental temperatures, the target temperatures are 32 ° C., 37 ° C.,
42 ° C. (the number of calibration points = 12). Further, the output value of the temperature sensor 107 when the environmental temperature was 25 ° C. was set as β. This β and the coefficients a to i and j are shown in Table 1 below.

As a comparative example, the linearizing means 311a
, That is, a thermometer that obtains the body temperature by substituting the output value x of the infrared sensor and the output value y of the temperature sensor into the above equation (1). This thermometer was calibrated to set the coefficients a _{1 to} i ₁ and j ₁ of the above equation (1). The conditions for this calibration were the same as in the present invention. The respective coefficients a _{1 to} i ₁ and j ₁ are shown in Table 1 below.

[0099]

[Table 1]

For the present invention and the comparative example, when the environmental temperature was set to 10 ° C., 20 ° C., and 30 ° C., respectively, the temperature of the target whose temperature was known was measured, and the actual temperature of the target and the measured value were measured. And the residual (error) was determined.

FIG. 9 shows the residual (S1) in the present invention when the environmental temperature is 10 ° C. and the residual (S2) in the comparative example.
And

FIG. 10 shows the residual (S3) in the present invention when the ambient temperature is 20 ° C. and the residual (S4) in the comparative example.

FIG. 11 shows the residual (S5) in the present invention when the ambient temperature is 30 ° C. and the residual (S6) in the comparative example.

As can be seen from the graphs of FIGS. 9 to 11, in the present invention, the calibration points (environmental temperatures: 7 ° C., 15 ° C., 2 ° C.)
(5 ° C., 35 ° C.), there is almost no residual. That is, in the present invention, the output value y from the temperature sensor is converted into y 'by the linearization means 311a so that the characteristic indicating the relationship between y' and the environmental temperature T becomes substantially linear, and the y value is converted to y '. Since the body temperature is obtained by using 'and the output value x of the infrared sensor, the measurement accuracy of the body temperature is high.

On the other hand, in the comparative example, the linearizing means 31
1a, so when the ambient temperature is 10 ° C,
When a residual of about 0.3 ° C occurs and the ambient temperature is 20 ° C,
A residual of about −0.1 ° C. occurs, and when the environmental temperature is 30 ° C., a residual of about 0.1 ° C. occurs, and measurement accuracy of body temperature is low.

Although the thermometer of the present invention has been described based on the embodiment shown in the accompanying drawings, the present invention is not limited to this, and each component may have any configuration having the same function. Can be replaced by

For example, in the above-described embodiment, the body temperature is obtained by using a third-order approximate polynomial for each of x and y ′. However, in the present invention, the order of the approximate polynomial is limited to the third order. However, for example, it may be primary, secondary, quaternary or higher.

In this case, the degree of the approximation polynomial is preferably higher than the second order (particularly, each of x and y 'is higher than the second order). Are more preferably three or more).

In the above embodiment, the linearizing means 311
a is configured to convert y into y ′ according to the above equations (2) and (3).
It is sufficient that y can be converted to y 'so that the characteristic indicating the relationship with the environmental temperature T becomes substantially linear. The equation (conversion equation) used when converting y to y' is the above (2). ) And (3) are not limited.

Further, the present invention may be configured so that a predetermined temperature correction is performed on the body temperature obtained from the above equation (5).

Although the above embodiment is directed to an ear thermometer, the present invention is not limited to an ear thermometer as long as it is an infrared thermometer that measures the body temperature by detecting the intensity of infrared rays emitted from a measurement site. .

[0112]

As described above, according to the infrared thermometer of the present invention, the characteristic indicating the relationship between the converted value (signal value) and the environmental temperature of the output value (direct signal value) from the temperature sensor. Since there is a linearization means for converting (a characteristic of a signal value depending on environmental temperature) to be substantially linear, it is possible to improve the measurement accuracy of the body temperature without increasing the number of calibration points. it can.

In particular, since the output value from the temperature sensor is converted by the linearization means without converting it into a temperature value,
There is no need to perform thermoelectric calibration, thus improving productivity and
It is advantageous for mass production.

[Brief description of the drawings]

FIG. 1 is a front view of a thermometer according to the present invention.

FIG. 2 is a side view of the thermometer of the present invention.

FIG. 3 is a cross-sectional view taken along line AA in FIG. 1, showing a state in which a probe cover is attached to a probe in the thermometer of the present invention.

FIG. 4 is a sectional side view schematically showing the internal structure of the thermometer of the present invention.

FIG. 5 is a perspective view showing a configuration example of a temperature measuring unit in the thermometer of the present invention.

FIG. 6 is a block diagram illustrating a circuit configuration example of a thermometer according to the present invention.

FIG. 7 is a block diagram (conceptual diagram) illustrating a configuration example of a calculation unit of a control unit according to the present invention.

FIG. 8 shows an environmental temperature T and R ′ (resistance value R of a temperature sensor).
Is a graph showing the relationship between the value of the equation (7) and the value converted by the equations (9).

FIG. 9 is a graph showing a residual (S1) in the present invention when the environmental temperature is 10 ° C. and a residual (S2) in a comparative example.

FIG. 10 is a graph showing a residual (S3) in the present invention when the environmental temperature is 20 ° C. and a residual (S4) in a comparative example.

FIG. 11 is a graph showing a residual (S5) in the present invention when the environmental temperature is 30 ° C. and a residual (S6) in a comparative example.

FIG. 12 is a graph showing a relationship between an environmental temperature T and a resistance value R of a temperature sensor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermometer 2 Thermometer main body 21 Casing 3 Power switch 4 Measurement switch 5 Display part 6 Probe 61 Base 62 Male screw 63 Tip outer peripheral part 64 Inclined part 7 Support base 71 Large diameter part 72 Small diameter part 73, 74 Male screw 8 Light guide 81 Protection Sheet 9 Ring nut 91 Female screw 92 Taper part 93 Engagement part 94 Tip surface 95 Groove 10 Temperature detection part 101 Infrared sensor 102 Thermopile (thermocouple array) 103 Hot junction 104 Cold junction 105 Heat insulation zone 106 Heat collection part 107 Temperature sensor 11 Probe cover 12 Body part 14 Film 15 Lip part 30 Circuit board 31 Control means 311 Operation part 311a Linearization means 311b Operation unit 312 Memory 313 Timer 32 A / D converter 33 Buzzer 40 Power supply unit

Claims (3)

[Claims] 1. An infrared sensor for detecting infrared rays emitted from a measurement site and a temperature sensor for detecting an environmental temperature, wherein a signal value from the infrared sensor and a signal value from the temperature sensor are converted into a signal value. In an infrared thermometer that calculates a body temperature value by substituting into an approximation polynomial as a parameter, the signal value from the temperature sensor to be substituted into the approximation polynomial has a characteristic that the dependence on the environmental temperature is substantially linear. Infrared thermometer. 2. The temperature sensor according to claim 1, wherein the temperature sensor is a thermistor, and converts a direct signal value from the thermistor so that a characteristic dependent on the environmental temperature becomes substantially linear. The infrared thermometer according to claim 1, wherein a signal value from the infrared thermometer is calculated. 3. The degree of the approximation polynomial is second or higher for each parameter of a signal value from the infrared sensor and a signal value from the temperature sensor.
Or the infrared thermometer according to 2.