JP2013072733A - Manufacturing method for clinical electronic thermometers - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce costs of a clinical electronic thermometer manufacturing process.SOLUTION: A manufacturing method for clinical electronic thermometers comprises a step of mounting a circuit to which a thermistor for temperature measurement is connected over a substrate; a step of inserting the substrate into a body case and fixing the thermistor within a metal cap; a step of soaking at least the whole of the metal cap in water in a constant-temperature bath; a step of determining whether or not a calibration value for use in temperature measurement has already been calculated; and a step of calculating, if the calibration value is determined not to have been calculated, the calibration value on the basis of the result of the temperature measurement in a state in which the whole of the metal cap is soaked in water in the constant-temperature bath and storing the value into memory means.

Description

  The present invention relates to a method for manufacturing an electronic thermometer.

  In the field of electronic thermometers, a single-input integrating A / D conversion circuit and a CR oscillation circuit have been conventionally used as a technique for measuring a resistance change of the thermistor accompanying a temperature change.

  A single-input integral type A / D converter circuit stores an amount of charge proportional to the resistance change of the thermistor when a predetermined power supply voltage is applied, and changes resistance when the stored charge is discharged. It is a circuit that can output an ON signal having a time proportional to.

  In the electronic thermometer using the single input integration type A / D conversion circuit, a system for accumulating charges via a reference resistor is added to the above circuit, and the accumulated charges are discharged via a thermistor. The temperature is calculated by adding a predetermined coefficient (calibration value) to the ratio of the discharge time of the battery and the discharge time when the charge accumulated via the reference resistor is discharged (for example, the following patent) Reference 1).

  On the other hand, in an electronic thermometer using a CR oscillation circuit, an oscillation circuit using a thermistor and a capacitor that oscillates when applied at a predetermined voltage, and a reference resistor and capacitor that oscillates when applied at a predetermined voltage are used. An oscillation circuit is provided, and the temperature is calculated by adding a predetermined coefficient (calibration value) to the ratio between the oscillation frequency of the thermistor and the capacitor and the oscillation frequency of the reference resistor and the capacitor.

  Here, these coefficients used to calculate the temperature need to take into account variations in the temperature characteristics of the thermistor and individual differences in the circuit to which the thermistor is connected. It is carried out.

  Specifically, in the manufacturing process of an electronic thermometer, the board on which the circuit is mounted is electrically connected to the calibration facility before being incorporated into the housing of the electronic thermometer, and then the thermistor portion is kept at a constant temperature. The calibration process is performed by putting it in the tank.

  FIG. 6 is a diagram schematically showing the manufacturing process of the electronic thermometer including the calibration process. As shown in FIG. 6, in step I, a circuit is mounted on the substrate, and in step II, the substrate on which the circuit is mounted is electrically connected to a calibration facility. In Step III, the thermistor is submerged in a thermostatic chamber controlled at 37 ° C. with a highly insulating liquid (Galden, registered trademark of Techno Alpha), and calibration processing is performed in the calibration facility. Is done. Thereafter, in step IV, the calibration equipment is removed, and a power source (battery) is mounted on the substrate in step V. Then, in step V, the substrate is fixed in the housing.

JP 2010-014501 A

  However, in the case of the manufacturing process as described above, since the substrate before being incorporated in the case of the electronic thermometer is put in the thermostat, a highly insulating liquid is used for the thermostat so that an electrical short circuit does not occur. There is a need to. For this reason, there exists a problem that manufacturing cost starts.

  This invention is made | formed in view of the said subject, and aims at reducing the cost in the manufacturing process of an electronic thermometer.

In order to achieve the above object, a method for manufacturing an electronic thermometer according to the present invention has the following configuration. That is,
A method of manufacturing an electronic thermometer including a thermistor for measuring temperature,
Mounting a circuit to which the thermistor is connected on a substrate;
Inserting the substrate into the body case and fixing the thermistor in a metal cap;
Submerging at least the entire metal cap in a thermostatic chamber;
Determining whether a calibration value used for the temperature measurement has been calculated;
When it is determined that the calibration value has not been calculated, the calibration value is calculated based on the result of the temperature measurement in a state where the entire metal cap is submerged in the thermostatic bath, and stored in the storage unit. And a step of performing.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to aim at the cost reduction in the manufacturing process of an electronic thermometer.

FIG. 1 is a diagram showing an external configuration of an electronic thermometer 100 according to an embodiment of the present invention. FIG. 2 is an internal block diagram showing a functional configuration of the electronic thermometer 100. FIG. 3 is a flowchart showing the flow of the calibration process and temperature measurement processing program of the electronic thermometer 100. FIG. 4 is a flowchart showing the flow of the body temperature measurement processing program of the electronic thermometer 100. FIG. 5 is a diagram schematically showing the flow of the manufacturing process of the electronic thermometer 100. FIG. 6 is a diagram schematically showing the flow of the manufacturing process of the conventional electronic thermometer. FIG. 7 is a flowchart showing a flow of a calibration process and a temperature measurement process program of a conventional electronic thermometer.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings as necessary.

[First Embodiment]
<1. External structure of electronic thermometer>
FIG. 1 is a diagram showing an external configuration of an electronic thermometer 100 according to an embodiment of the present invention. FIG. 1A shows a plan view and FIG. 1B shows a bottom view. Reference numeral 101 denotes a main body case (housing), and 102 denotes a housing cap, in which an electronic circuit such as a control unit 220 described later, a battery (power supply unit) 230, and the like are stored. The body case (housing) 101 and the housing cap 102 are screwed with screws 106. Instead of screwing with the screw 106, the main body case (housing) 101 and the housing cap 102 are engaged via the O-ring, and then the main body case (housing) 101 and the housing cap 102 are engaged. These joints may be fused by ultrasonic waves over the entire circumference.

  Reference numeral 103 denotes a stainless steel metal cap in which a thermistor (details will be described later) for measuring temperature is stored. Reference numeral 104 denotes a power ON / OFF switch, which is turned on when pressed once and turned off when pressed again.

  The power ON / OFF switch 104 may further have a backlight on / off function and a buzzer ON / OFF function. Alternatively, a permanent magnet is provided in a storage case (not shown) of the electronic thermometer 100, and a magnet reed switch is provided in place of the power ON / OFF switch 104 of the electronic thermometer 100, whereby the electronic thermometer 100 is stored in the storage case. You may comprise so that a power supply may be turned ON whenever it removes from.

  Reference numeral 105 denotes a display unit that displays the body temperature of the subject. A transparent window member 105a covers the display unit 105. The window member 105a and the main body case (housing) 101 are preferably formed in a liquid-tight manner by two-color shaping.

<2. Functional structure of electronic thermometer>
FIG. 2 is an internal block diagram showing a functional configuration of the electronic thermometer 100 according to the present embodiment.

  The electronic thermometer 100 includes an oscillation circuit unit 210, a control unit 220, a power supply unit 230, a display unit 240, and an audio output unit 250.

  In the oscillation circuit unit 210, a reference resistor 211 and a thermistor 212 connected in parallel to each other are connected in series to a capacitor 213. The voltage V is alternately applied to the both ends of the system including the reference resistor 211 and the capacitor 213 and the both ends of the system including the thermistor 212 and the capacitor 213 through the voltage switching unit 221 to be discharged. It is configured as follows.

  Here, the reference resistor 211 is a resistance element having a constant resistance value regardless of variations in ambient temperature. For this reason, when the voltage V is constant, the discharge time when the charge stored in the capacitor 213 is discharged via the reference resistor 211 is constant.

  On the other hand, the thermistor 212 is a resistance element whose resistance value varies according to variations in ambient temperature. For this reason, the discharge time when the charge stored in the capacitor 213 is discharged via the thermistor 212 varies according to the ambient temperature.

  That is, when the voltage V is constant, the discharge time when the charge stored via the reference resistor 211 is discharged is always constant, and the discharge time when the charge stored via the thermistor 212 is discharged. Depends on the ambient temperature.

  The control unit 220 includes a voltage switching unit 221, an A / D conversion unit 222, a calculation unit 223, and a storage unit 224.

  The voltage switching unit 221 performs switching for alternately applying the voltage V to the reference resistor 211 and the thermistor 212 arranged in the oscillation circuit unit 210 when temperature measurement is started.

  The A / D conversion unit 222 includes a comparator, and is predetermined while the capacitor 213 has a voltage equal to or higher than a voltage (for example, 0.25 V) of a predetermined ratio of the voltage V applied via the voltage switching unit 221. The signal is output. As a result, the A / D converter 222 outputs an ON signal corresponding to the discharge time as a digital signal. As described above, the capacitor 213 and the A / D conversion unit 222 form a single input integration type A / D conversion circuit.

  The calculation unit 223 includes a CPU and a memory, and implements various functions by executing programs (calibration processing and temperature measurement processing program 225, body temperature measurement processing program 226, etc.) stored in the storage unit 224. In the following description, among the various functions realized by the calculation unit 223, the calibration processing function, the temperature measurement processing function, and the body temperature measurement processing function will be mainly described in detail.

  Whether the calibration process is executed or the temperature measurement process is executed, the calculation unit 223 measures the ON time (discharge time) of the digital signal output from the A / D conversion unit 222. Specifically, the discharge time when discharging the charge accumulated in the capacitor 213 via the reference resistor 211 and the discharge time when discharging the charge accumulated in the capacitor 213 via the thermistor 212 are measured. To do.

  Then, during the calibration process, the calculation unit 223 calculates a coefficient (calibration value) α used for temperature calculation based on each measured discharge time, and stores it in the storage unit 224. On the other hand, during the temperature measurement process, the temperature is calculated based on the following equation using the measured discharge times and the coefficient α stored in the storage unit 224.

T = 37 ° C. × (Tth / Tref) × α (1)
α = Tref37 / Tth37 (2)
In the above formula, 37 ° C. is a reference temperature, which is the water temperature of the thermostatic chamber in the calibration process described later.

  Tref37 indicates a discharge time measured when a voltage V is applied / discharged to both ends of the system of the reference resistor 211 and the capacitor 213 under the reference temperature in the calibration process. Tth37 indicates a discharge time measured when a voltage V is applied / discharged across the system of the thermistor 212 and the capacitor 213 under the reference temperature in the calibration process.

  Further, Tref indicates a discharge time measured when the voltage V is applied / discharged to both ends of the system of the reference resistor 211 and the capacitor 213 in the temperature measurement process. Tth represents the discharge time measured when the voltage V is applied / discharged to both ends of the thermistor 212 and capacitor 213 in the temperature measurement process.

  The storage unit 224 stores the coefficient α calculated by the calibration process in addition to various programs. The stored coefficient α is read by the calculation unit 223 and used for calculating the temperature T during the temperature measurement process. The storage unit 224 stores a calibrated code indicating that the calibration process has been completed. Thereby, in the calculating part 223, the electronic thermometer 100 can recognize whether the calibration process has been completed. Further, the storage unit 224 stores the body temperature data of the subject calculated based on the calculated temperature during the temperature measurement process.

  The power supply unit 230 supplies power to each unit (210, 220, 240) of the electronic thermometer 100. When the power ON / OFF switch 104 is pressed, the power supply unit 230 supplies power to each unit, and the calculation unit 223 starts executing a calibration process and a temperature measurement process program or a body temperature measurement process program. Further, when the power ON / OFF switch 104 is further pressed, the power supply from the power supply unit 230 to each unit is cut off.

The display unit 240 (corresponding to the display unit 105 in FIG. 1) displays the body temperature of the subject calculated based on the calculated temperature in the body temperature measurement process. In addition, the past temperature data of the subject stored in the storage unit 224 is displayed. The voice output unit 250 outputs a voice to the subject when the body temperature of the subject is calculated.
<3. Flow of calibration processing and temperature measurement processing program>
Next, the flow of the calibration process and temperature measurement process program in the electronic thermometer 100 will be described.
<3.1 General Electronic Thermometer Calibration Process and Temperature Measurement Processing Program Flow>
First, a flow of a general electronic thermometer calibration process and a temperature measurement process program for comparison will be described. FIG. 7 is a flowchart showing the flow of a general electronic thermometer calibration process and a temperature measurement process program.

  When the substrate is electrically connected to the calibration facility, the flowchart shown in FIG. 7 (execution of the calibration processing and temperature measurement processing program) is started. In step S701, the memory in the arithmetic unit is cleared by executing an initialization process on the substrate side.

  In step S702, it is determined on the substrate side whether or not the terminal to be short-circuited during the calibration process is short-circuited. If it is determined in step S702 that the terminal is short-circuited, the process proceeds to step S711, and calibration processing is started under the instruction from the calibration facility.

  In step S711, it is determined whether or not an instruction to measure the discharge time when the electric charge accumulated in the capacitor 213 is discharged from the calibration facility via the thermistor 212 is input on the board side. If it is determined in step S711 that an instruction has been input from the calibration facility, the process proceeds to step S712, where electric charge is accumulated in the capacitor 213 via the thermistor 212 and then discharged to measure the discharge time (Tth). To do. Further, the measured discharge time (Tth) is transmitted to the calibration facility.

  In step S713, it is determined whether or not an instruction to measure the discharge time when the charge accumulated in the capacitor 213 is discharged from the calibration facility via the reference resistor 211 is input on the board side. If it is determined in step S713 that an instruction has been input from the calibration facility, the process proceeds to step S714, where charge is accumulated in the capacitor 213 via the reference resistor 211 and then discharged, thereby discharging time (Tref). Measure. The measured discharge time (Tref) is transmitted to the calibration facility.

  In the calibration equipment, after calculating the coefficient α using the above equation (2) based on the discharge time (Tth, Tref) transmitted from the substrate, the calculated coefficient α is transmitted to the substrate.

  In step S715, it is determined whether or not the coefficient α is transmitted from the calibration facility. If it is determined that the coefficient α is transmitted, the process proceeds to step S716, and after the coefficient α transmitted from the calibration facility is stored in the storage unit. Then, the calibration processing and temperature measurement processing program is terminated.

  On the other hand, if it is determined in step S702 that the terminal is not short-circuited, the process proceeds to step S721, and temperature measurement processing is started on the substrate side.

  In step S721, the coefficient α stored in the storage unit is read, and in step S722, the discharge time (Tth) when discharging the charge accumulated in the capacitor via the thermistor is measured.

  Further, in step S723, a discharge time (Tref) when the electric charge accumulated in the capacitor is discharged through the reference resistor is measured.

  In step S724, based on the coefficient α read in step S721, the discharge time (Tth) measured in step S722, and the discharge time (Tref) measured in step S723, the above equation (1) is obtained. To calculate the temperature.

  In step S725, the temperature data calculated in step S724 is transmitted to the body temperature measurement program.

In step S726, it is determined whether or not a temperature measurement end instruction is issued. If it is determined that there is no temperature measurement end instruction, the process returns to step S722 and the temperature measurement process is continued. On the other hand, if it is determined in step S726 that a temperature measurement end instruction has been issued, the calibration processing and temperature measurement processing program ends.
<3.2 Flow of Calibration Process and Temperature Measurement Processing Program of Electronic Thermometer According to this Embodiment>
Next, the calibration process and temperature measurement process program 225 in the electronic thermometer 100 will be described with reference to FIG. FIG. 3 is a flowchart showing the flow of the calibration processing and temperature measurement processing program 225 in the electronic thermometer 100.

  In step S301, the memory in the calculation unit 223 is cleared by executing an initialization process.

  In step S302, it is determined whether the coefficient (calibration value) α has been calculated. Specifically, the storage unit 224 is referenced to determine whether or not a calibrated code is stored at a predetermined address. If it is determined in step S302 that no calibrated code is stored, it is determined that the calibration process has not been executed, and the process proceeds to step S311 to start the calibration process.

  Here, in the case of the electronic thermometer 100 according to the present embodiment, since it is assumed that the calibration process is performed after the substrate is fixed to the housing, the terminals on the substrate are short-circuited like a general electronic thermometer. By doing so, the calibration process cannot be started. Therefore, the electronic thermometer 100 according to the present embodiment is configured to make a determination based on the presence or absence of a calibrated code stored at a predetermined address in the storage unit 224.

  In step S311, it is determined whether a calibration condition is satisfied. The calibration condition is that the thermistor 212 is immersed in a thermostatic chamber controlled to a reference temperature (for example, 37 ° C.), so that the temperature rises and then reaches equilibrium (converges within a predetermined range). )) State.

  Specifically, the process of measuring the discharge time when the charge accumulated in the capacitor 213 is discharged via the thermistor 212 is repeated every predetermined period. As a result, the calculation unit 223 can recognize that the temperature has reached an equilibrium state after detecting the tendency of temperature increase (because the coefficient α is not calculated, it is not possible to calculate an accurate temperature). Can be recognized that the temperature is rising, and that the temperature has reached equilibrium, etc.).

  The reason that the calibration condition is that the temperature has reached an equilibrium state is that an error will occur if the coefficient α is calculated based on the result during the temperature rise. In the case of a typical electronic thermometer, it is configured to be connected to a calibration facility and operate based on an instruction from the calibration facility side, whereas in the case of the electronic thermometer 100 according to the present embodiment, the electronic thermometer 100 itself This is because the measurement start timing is determined.

  In step S311, when it is determined that the calibration condition is satisfied, the process proceeds to step S312, and the discharge time (Tth) when the charge accumulated in the capacitor 213 is discharged via the thermistor 212 is measured.

  Further, in step S313, the discharge time (Tref) when the charge accumulated in the capacitor 213 is discharged via the reference resistor 211 is measured.

  In step S314, the coefficient α is calculated using the above equation (2) based on the discharge time (Tth) measured in step S312 and the discharge time (Tref) measured in step S313.

  In step S315, initialization processing is executed, and data stored in the memory of the calculation unit 223 is cleared. Furthermore, in step S316, the coefficient α calculated in step S314 is stored in the storage unit 224. In step S317, the calibrated code is stored at a predetermined address in the storage unit 224, and the calibration process is terminated. Thereby, thereafter, the calculation unit 223 can recognize that the electronic thermometer 100 has been calibrated.

  On the other hand, if it is determined in step S302 that the calibrated code is stored in the storage unit 224, it is determined that the calibration process has already been performed, the process proceeds to step S321, and the temperature measurement process is started.

  In step S321, the coefficient α stored in the storage unit 224 is read, and in step S322, the discharge time (Tth) when the charge accumulated in the capacitor 213 is discharged via the thermistor 212 is measured.

  Further, in step S323, the discharge time (Tref) when the charge accumulated in the capacitor 213 is discharged via the reference resistor 211 is measured.

  In step S324, the above equation (1) is calculated based on the coefficient α read in step S321, the discharge time (Tth) measured in step S322, and the discharge time (Tref) measured in step S323. To calculate the temperature.

  In step S325, the temperature data calculated in step S324 is transmitted to the body temperature measurement processing program 226.

  In step S326, it is determined whether or not there is a temperature measurement end instruction. If it is determined that there is no temperature measurement end instruction, the process returns to step S322 and the temperature measurement process is continued. On the other hand, if it is determined in step S326 that a temperature measurement end instruction has been issued, the calibration processing and temperature measurement processing program 225 ends.

<4. Flow of temperature measurement processing program>
Next, the flow of the body temperature measurement processing program 226 in the electronic thermometer 100 will be described. Here, the flow of the body temperature measurement process of the equilibrium temperature prediction formula will be described, but the present invention is not limited to this, and is applicable to an actual measurement type electronic thermometer and a prediction / measurement type electronic thermometer.

  When the power is turned on and the electronic thermometer 100 is attached to the measurement site of the subject, the electronic thermometer 100 starts temperature measurement at a predetermined cycle, and predicts the body temperature of the subject based on the time change of the acquired temperature data. To do.

  FIG. 4 is a flowchart showing the flow of the body temperature measurement processing program 226 in the electronic thermometer 100. Hereinafter, the flow of the body temperature measurement process in the electronic thermometer 100 will be described with reference to FIG.

  When the power supply unit 230 of the electronic thermometer 100 is turned on, execution of the body temperature measurement processing program 226 shown in FIG. 4 is started. In parallel, the temperature measurement process of FIG. 3 is started (the calibration process and the temperature measurement process program 225 are executed and the temperature measurement process is started when it is determined that the calibration has been completed in step S302), and a predetermined interval is reached. For example, since temperature data calculated every 0.5 seconds is output, this is acquired in step S401.

  In step S402, it is determined whether a body temperature measurement start condition is satisfied. Specifically, the degree of increase from the value of the temperature data calculated by the previous temperature measurement (that is, the value of the temperature data before 0.5 seconds) has become a predetermined value (for example, 1 ° C.) or more. Judge whether or not.

  When it is determined that the degree of increase is equal to or greater than a predetermined value, it is determined that the body temperature measurement start condition is satisfied, and the timing at which the temperature data is measured is set as a reference point (t = 0) for predictive body temperature calculation. . That is, in the electronic thermometer 100, when a rapid temperature rise is measured, it is considered that the subject wears the electronic thermometer 100 at a predetermined measurement site (for example, armpit).

  If it is determined in step S402 that the body temperature measurement start condition is satisfied, the process proceeds to step S403, and temperature data acquisition is started. Specifically, the output temperature data and the timing at which the temperature data is measured are stored in the RAM in the calculation unit 223 as time series data.

  In step S404, the predicted body temperature is calculated by a predetermined prediction formula using the temperature data stored in step S403.

  In step S405, after a predetermined time (for example, 25 seconds) has elapsed from the reference point (t = 0), a predicted value in a certain section (for example, t = 25 to 30 seconds) calculated in step S404 is set in advance. It is determined whether or not the predicted establishment condition is satisfied. Specifically, it is determined whether or not the temperature is within a predetermined range (for example, 0.1 ° C.).

  If it is determined in step S405 that the prediction satisfaction condition is satisfied, the process proceeds to step S406 to instruct the end of the temperature measurement (the temperature measurement process in FIG. 3 ends in step S326). In step S407, a sound indicating that the calculation of the predicted body temperature has been completed is output, and the calculated predicted body temperature is displayed on the display unit 240.

  On the other hand, if it is determined in step S405 that the prediction satisfaction condition is not satisfied, the process proceeds to step S409. In step S409, it is determined whether a predetermined time (for example, 45 seconds) has elapsed from the reference point (t = 0). If it is determined that the time has elapsed, the temperature measurement is forcibly terminated. In addition, when forcedly ending, the predicted body temperature calculated at that time is displayed on the display unit 240 (step S407).

  In step S408, it is determined whether a body temperature measurement end instruction has been accepted. If it is determined in step S408 that a body temperature measurement end instruction has not been received, the process returns to step S402.

  On the other hand, if it is determined in step S408 that a body temperature measurement end instruction has been received, the body temperature measurement processing program 226 is terminated and the power supply unit 230 is turned off.

<5. Electronic thermometer manufacturing process flow>
Next, the manufacturing process of the electronic thermometer 100 will be described. FIG. 5 is a diagram schematically showing a manufacturing process of the electronic thermometer in which the calibration processing and temperature measurement processing program 225 shown in FIG. 3 is stored. As shown in FIG. 5, in step I, the circuit to which the thermistor 212 is connected is mounted on the substrate. In step II, the substrate is inserted into the main body case 101, and the thermistor 212 is bonded to the metal cap 103. It is fixed with an agent.

  In Step III, the electronic thermometer 100 is connected to a calibration facility (a plurality of electronic thermometers 100 can be connected), and at least the entire metal cap 103 is submerged in the thermostat and a calibration process is executed. Note that at least the steps so far are performed automatically.

  Further, in Step IV, the battery is inserted and mounted on the circuit, and the O-ring and the housing cap 102 are attached to the main body case (housing) 101 (this process is performed automatically). Or may be done manually). After that, if necessary, the joint between the main body case 101 and the housing cap 102 is ultrasonically welded over the entire circumference, and the window member 105a and the main body case (housing) 101 are liquid-formed by two-color molding. By forming it densely, the liquid tightness of the electronic thermometer 100 is maintained (in this case, the battery cannot be replaced).

  On the other hand, when the ultrasonic welding is not performed, the housing cap 102 is screwed to the main body case 101 with a screw (this process may be performed automatically or manually). In this case, the battery can be replaced).

  As is clear from the above description, the electronic thermometer 100 according to the present embodiment has a configuration in which the calibration processing and temperature measurement processing program 225 is arranged. In the program, it is determined whether or not the calibration is completed based on the calibrated code, and when it is determined that the calibration is not completed, the calibration process is automatically executed to obtain the coefficient α.

  Accordingly, it is not necessary to short-circuit the terminals on the substrate during the calibration process, and the calibration process can be executed after the substrate to which the thermistor is connected is fixed to the casing in the manufacturing process.

  As a result, it is no longer necessary to use a highly insulating (ie, inert) liquid such as Fluorinert or Galden in the thermostatic chamber, and water can be used, thereby reducing manufacturing costs. It became.

  Further, the electronic thermometer 100 according to the present embodiment is configured to wait until the calibration condition is satisfied before starting the calibration process, and measure the discharge time when the calibration condition is satisfied.

  As a result, the coefficient used for calculating the temperature can be calculated without error.

[Second Embodiment]
In the first embodiment, the electronic thermometer using a single input integral conversion circuit has been described. However, the present invention is not limited to this, and for example, a CR oscillation circuit including a thermistor, a reference resistor, and a capacitor is used. It can also be applied to the electronic thermometer used. In this case, the coefficient (calibration value) α is calculated by performing temperature measurement processing based on the ratio of the oscillation frequency of the thermistor and the capacitor and the ratio of the oscillation frequency of the reference resistor and the capacitor.

  In the first embodiment, the electronic thermometer 100 determines whether or not the calibration process has been completed based on whether or not a calibrated code is stored at a predetermined address in the storage unit 224. The present invention is not limited to this, and it may be configured to determine whether or not the electronic thermometer 100 has been calibrated based on whether or not the coefficient (calibration value) α is stored in the storage unit 224.

DESCRIPTION OF SYMBOLS 100: Electronic thermometer, 101: Main body case (casing), 102: Housing | casing cap, 103: Metal cap, 104: Power supply ON / OFF switch, 105: Display part, 106: Screw, 211: Reference resistor, 212: Thermistor 213: Capacitor, 221: Voltage switching unit

Claims (6)

A method of manufacturing an electronic thermometer including a thermistor for measuring temperature,
Mounting a circuit to which the thermistor is connected on a substrate;
Inserting the substrate into the body case and fixing the thermistor in a metal cap;
Submerging at least the entire metal cap in a thermostatic chamber;
Determining whether a calibration value used for the temperature measurement has been calculated;
When it is determined that the calibration value has not been calculated, the calibration value is calculated based on the result of the temperature measurement in a state where the entire metal cap is submerged in the thermostatic bath, and stored in the storage unit. The manufacturing method of the electronic thermometer characterized by including these processes.   The method for manufacturing an electronic thermometer according to claim 1, further comprising a step of mounting a battery on the circuit and mounting a housing cap to the main body case via an O-ring.   The method for manufacturing an electronic thermometer according to claim 2, further comprising a step of screwing the main body case and the housing cap.   The method for manufacturing an electronic thermometer according to claim 2, further comprising a step of fusing the entire circumference of a joint portion between the main body case and the housing cap with ultrasonic waves.   2. The method of manufacturing an electronic thermometer according to claim 1, wherein the determining step determines that the calibration value has been calculated when the calibration value is already stored in the storage unit.   The determining step determines that the calibration value has been calculated when a code indicating that the calibration value has been calculated is already stored at a predetermined address of the storage means. The manufacturing method of the electronic thermometer of Claim 1.

Images