Temperature starting circuit for electronic thermometer, electronic thermometer and temperature measuring method

Abstract

The invention relates to the technical field of electronic thermometers, and discloses a temperature starting circuit for an electronic thermometer, the electronic thermometer and a temperature measurement method, and the starting circuit comprises a resistance measurement control unit, a temperature judgment unit, an LCD refresh signal generation unit, a phase inverter INV1, a phase inverter INV2, a phase inverter INV3, an OR gate OR1, an AND gate AND1, an AND gate AND2 and a D trigger DFF1. In actual use, when the temperature starting circuit works, whether the temperature of the thermistor measured for the first time is within a set interval or not and whether the temperature value measured later rises or not are judged, so that whether the temperature contacted with the electronic thermometer is the environment temperature or the human body temperature is judged, and then whether the electronic thermometer directly enters a stability judgment stage or not is judged; and the accuracy of the display result of the electronic thermometer is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic thermometers, and particularly to a temperature starting circuit for an electronic thermometer, an electronic thermometer, and a temperature measuring method. Background Art

[0002] In order to replace the traditional mercury thermometer and quickly measure body temperature, the electronic thermometer came into being. The working process of the existing electronic thermometer can be sequentially divided into a full display stage, a display memory temperature stage, a display self-check temperature stage, a measurement stage, a stability judgment stage, and a beeping stage according to the running program; Among them, the full display stage is used to detect whether the LCD screen can correctly display all contents, and outputs a full display end signal after the full display stage ends; the display memory temperature stage is used to display the temperature at the time of the previous shutdown; the self-check temperature displayed in the display self-check temperature stage is determined according to the temperature of the reference resistance measured twice; the measurement stage is used to measure the temperature on the thermistor; the stability judgment stage is used to judge whether the measured body temperature has reached stability; in the beeping stage, the user is reminded that the measurement has ended and the measured temperature value of the electronic thermometer can be viewed; In addition, the process of measuring the resistance of the existing electronic thermometer is as follows: first, perform two consecutive reference resistance measurements. If the temperatures measured twice are the same, then display 37°C / 98.6°F in the display self-check temperature stage; among them, the start of measuring the reference resistance in this stage is controlled and enabled by the corresponding signal; after the self-check stage, the temperature is measured in the order of first measuring the reference resistance and then measuring the thermistor, and the temperature value on the LCD screen is updated in real time; in addition, the first measurement of the thermistor is also enabled by the corresponding control signal; In addition, when the existing electronic thermometer performs LCD liquid crystal display, a special LCD control signal is required, that is, after there is an LCD control signal, the LCD liquid crystal display screen displays information.

[0003] For the existing electronic thermometer, when it is used to quickly measure the human body temperature, if the electronic thermometer is not promptly placed in the temperature measurement part after being turned on by pressing the button, the electronic thermometer will always measure the ambient temperature, and then perform stability judgment and beeping after reaching the stability judgment time. And this measurement process will cause the stability judgment of the thermometer to be the ambient temperature rather than the human body temperature, resulting in an error in use and inaccurate temperature measurement. Summary of the Invention

[0004] In view of the deficiencies of the background art, the present invention provides a temperature starting circuit for an electronic thermometer, an electronic thermometer, and a temperature measuring method. On the basis of being compatible with the existing electronic thermometer, by processing the measured temperature in the display self-check temperature stage, it is judged whether the electronic thermometer is connected to the ambient temperature or the human body temperature when it is turned on, so as to determine whether to enter the stability judgment stage, thereby improving the reliability of the electronic thermometer.

[0005]

[0005] In order to solve the above technical problems, in a first aspect, the present invention provides the following technical solution: a temperature starting circuit for an electronic thermometer, including a resistance measurement control unit, a temperature judgment unit, an LCD refresh signal generation unit, an inverter INV1, an inverter INV2, an inverter INV3, an OR gate OR1, an AND gate AND1, an AND gate AND2, and a D flip-flop DFF1; The resistance measurement control unit generates a measurement signal RF1st and a measurement signal RS1st based on the input full display end signal. The measurement signal RS1st is later than the measurement signal RF1st. The measurement signal RF1st is used to turn on the reference resistance measurement of the electronic thermometer, and the measurement signal RS1st is used to turn on the thermistor measurement of the electronic thermometer; The temperature judgment unit is used to judge whether the temperature measured by the thermistor is within the set range, and outputs a judgment signal TP based on the judgment result; The LCD refresh signal generation unit is used to judge the temperature on the thermistor, and generates an LCD refresh signal based on the judgment result, the measurement signal RF1st, and the measurement signal RS1st; The measurement signal RS1st is input to the inverter INV1, the judgment signal TP is input to the inverter INV2, the measurement signal RF1st is input to the inverter INV3. The output end of the inverter INV1 and the output end of the inverter INV2 are electrically connected to the two input ends of the OR gate OR1. The output end of the OR gate OR1, the output end of the inverter INV3, and the two input ends of the AND gate AND1 are electrically connected. The two input ends of the AND gate AND2 are respectively connected to the input end of the AND gate AND1 and the LCD refresh signal output end of the LCD refresh signal generation unit. The output end of the AND gate AND2 is connected to the CP end of the D flip-flop DFF1. The CDN end of the D flip-flop DFF1 is used to input a reset signal RESET. The Q output end of the D flip-flop DFF1 is used to output an enable signal EnStaTime, and the enable signal EnStaTime is used to make the electronic thermometer enter the stability judgment stage.

[0006]

[0006] In a certain implementation manner of the first aspect, the resistance measurement control unit includes an inverter INV4, a D flip-flop DFF2, a D flip-flop DFF3, a D flip-flop DFF4, a NOR gate NOR1, and a NOR gate NOR2; The input end of the inverter INV4 is used to input the full display end signal. The output end of the inverter INV4 is electrically connected to the D input end of the D flip-flop DFF2. The Q output end of the D flip-flop DFF2 is electrically connected to the D input end of the D flip-flop DFF3; The two input terminals of the NOR gate NOR1 are electrically connected to the QN output terminal of the D flip-flop DFF2 and the Q output terminal of the D flip-flop DFF3 respectively, and the output terminal of the NOR gate NOR1 is used to output the measurement signal RF1st; The two input terminals of the NOR gate NOR2 are electrically connected to the QN output terminal of the D flip-flop DFF3 and the Q output terminal of the D flip-flop DFF4 respectively, and the output terminal of the NOR gate NOR2 is used to output the measurement signal RS1st; The CP terminals of the D flip-flop DFF2, the CP terminal of the D flip-flop DFF3, and the CP terminal of the D flip-flop DFF4 are used to input a clock signal; The CDN terminals of the D flip-flop DFF2, the CDN terminal of the D flip-flop DFF3, and the CDN terminal of the D flip-flop DFF4 are used to input a reset signal RESET.

[0007] In a certain implementation manner of the first aspect, the clock signal is generated by dividing the system clock of the electronic thermometer.

[0008] In a certain implementation manner of the first aspect, the system clock is 32.768KHz, and the clock signal is generated after dividing the system clock by 32768.

[0009] In a certain implementation manner of the first aspect, the temperature judgment unit includes a NOR gate NOR3, a NOR gate NOR4, a NOR gate NOR5, an AND gate AND3, an AND gate AND4, an AND gate AND5, an AND gate AND6, an OR gate OR2, and a NAND gate NAND1; The two input terminals of the NOR gate NOR3, the two input terminals of the NOR gate NOR4, the two input terminals of the NOR gate NOR5, the two input terminals of the AND gate AND6, one input terminal of the AND gate AND3, and one input terminal of the AND gate AND4 are used to input the BCD codes corresponding to the temperature measured by the thermistor; the output terminal of the NOR gate NOR3 is electrically connected to the other input terminal of the AND gate AND3, the output terminal of the NOR gate NOR4 is electrically connected to the other input terminal of the AND gate AND4, and the output terminal of the NOR gate NOR5, the output terminal of the AND gate AND6, and the two input terminals of the AND gate AND5 are electrically connected; The output terminal of the AND gate AND3, the output terminal of the AND gate AND4, and the two input terminals of the OR gate OR2 are electrically connected, the output terminal of the OR gate OR2, the output terminal of the AND gate AND5, and the two input terminals of the NAND gate NAND1 are electrically connected, and the output terminal of the NAND gate NAND1 outputs the judgment signal.

[0010] In a certain implementation manner of the first aspect, the third and fourth bits of the BCD code corresponding to the units digit of the temperature measured by the thermistor are input to the two input terminals of the NOR gate NOR3; One input terminal of the AND gate AND3 inputs the second digit of the BCD code corresponding to the units digit of the temperature measured by the thermistor; Two input terminals of the NOR gate NOR4 input the second digit and the fourth digit of the BCD code corresponding to the units digit of the temperature measured by the thermistor; One input terminal of the AND gate AND4 inputs the third digit of the BCD code corresponding to the units digit of the temperature measured by the thermistor; Two input terminals of the NOR gate NOR5 input the third digit and the fourth digit of the BCD code corresponding to the tens digit of the temperature measured by the thermistor; Two input terminals of the AND gate AND6 input the first digit and the second digit of the BCD code corresponding to the tens digit of the temperature measured by the thermistor.

[0011] In a certain implementation manner of the first aspect, the LCD refresh signal generation unit includes a numerical comparison unit, an OR gate OR3, an OR gate OR4, an AND gate AND6, and an RS flip-flop SR1; The numerical comparison unit is used to compare the temperature measured by the thermistor with the stored memory temperature of the electronic thermometer, and input a high-level signal to one input terminal of the OR gate OR3 after the temperature measured by the thermistor is greater than the memory temperature. Two input terminals of the OR gate OR4 are used to input a measurement signal RF1st and a measurement signal RS1st. The output terminal of the OR gate OR4 is electrically connected to the other input terminal of the OR gate OR3. The output terminal of the OR gate OR3 is electrically connected to the S input terminal of the RS flip-flop SR1; The R input terminal of the RS flip-flop SR1 is used to input a signal RSBeg. The signal RSBeg is the pulse signal at the start of each measurement of the thermistor of the electronic thermometer. The Q output terminal of the RS flip-flop SR1 is electrically connected to one input terminal of the AND gate AND6. The other input terminal of the AND gate AND6 is used to input a signal RSEnd. The signal RSEnd is the pulse signal generated after each measurement of the thermistor of the electronic thermometer ends. The CDN terminal of the RS flip-flop SR1 is used to input a reset signal RESET. The output terminal of the AND gate AND6 is used to output an LCD refresh signal.

[0012] In the second aspect, the present invention provides an electronic thermometer, including the above temperature calculation circuit.

[0013] In the third aspect, the present invention provides a temperature measurement method, which is implemented by the above electronic thermometer. The steps when the electronic thermometer measures temperature are as follows: S1: The electronic thermometer starts and performs full display; S2: The electronic thermometer displays the memory temperature; S3: The electronic thermometer displays 37°C or 98.6°F; S4: The electronic thermometer displays the temperature of the thermistor measured for the first time; S5: Determine whether the temperature of the measured thermistor is within the starting algorithm temperature range. If it is within the range, execute step S6; otherwise, execute step S7; S6: Determine whether the measured temperature is rising. If the temperature is rising, execute step S7; otherwise, return to step S4; S7: The electronic thermometer enters the stability judgment stage.

[0014] In a certain implementation manner of the third aspect, the endpoint values of the starting algorithm temperature range are adjustable.

[0015] The beneficial effects of the present invention compared with the prior art are as follows: In actual use, when the temperature starting circuit of the present invention is working, by judging whether the temperature of the thermistor measured for the first time is within the set range and whether the temperature value measured later is rising, it is determined whether the electronic thermometer is in contact with the ambient temperature or the human body temperature, and then it is determined whether to directly enter the stability judgment stage, improving the accuracy of the display result of the electronic thermometer. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic structural diagram of the temperature starting circuit in Embodiment 1; Figure 2 It is a circuit diagram of the resistance measurement control unit in Embodiment 1; Figure 3 It is a circuit diagram of the temperature judgment unit in Embodiment 1; Figure 4 It is a circuit diagram of the LCD refresh signal generation unit in Embodiment 1; Figure 5 It is a relevant signal waveform diagram of the circuit operation of the present invention in Embodiment 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] Now, the present invention will be further described in detail with reference to the accompanying drawings. These drawings are all simplified schematic diagrams, only illustrating the basic structure of the present invention in a schematic manner, so they only show the components related to the present invention.

[0018] Embodiment 1 As Figure 1 shown, the temperature starting circuit for an electronic thermometer provided in this embodiment includes a resistance measurement control unit 1, a temperature judgment unit 2, an LCD refresh signal generation unit 3, an inverter INV1, an inverter INV2, an inverter INV3, an OR gate OR1, an AND gate AND1, an AND gate AND2, and a D flip-flop DFF1.

[0019] In this embodiment, the connection relationships of the above units and devices are as follows: The resistance measurement control unit 1 generates a measurement signal RF1st and a measurement signal RS1st based on the input full display end signal AllDisEnd. The measurement signal RS1st is later than the measurement signal RF1st. The measurement signal RF1st is used to turn on the reference resistance measurement of the electronic thermometer, and the measurement signal RS1st is used to turn on the thermistor measurement of the electronic thermometer; The temperature judgment unit 2 is used to judge whether the temperature measured by the thermistor is within the set range, and outputs a judgment signal TP based on the judgment result; The LCD refresh signal generation unit 3 is used to judge the temperature on the thermistor, and generates an LCD refresh signal LCDRefresh based on the judgment result, the measurement signal RF1st and the measurement signal RS1st; The measurement signal RS1st is input to the inverter INV1, the judgment signal TP is input to the inverter INV2, the measurement signal RF1st is input to the inverter INV3. The output end of the inverter INV1 and the output end of the inverter INV2 are electrically connected to the two input ends of the OR gate OR1. The output end of the OR gate OR1 and the output end of the inverter INV3 are electrically connected to the two input ends of the AND gate AND1. The two input ends of the AND gate AND2 are respectively electrically connected to the input end of the AND gate AND1 and the LCD refresh signal output end of the LCD refresh signal generation unit. The output end of the AND gate AND2 is electrically connected to the CP end of the D flip-flop DFF1. The CDN end of the D flip-flop DFF1 is used to input a reset signal RESET. The Q output end of the D flip-flop DFF1 is used to output an enable signal EnStaTime. The enable signal EnStaTime is used to make the electronic thermometer enter the stability judgment stage.

[0020] In actual use, when the temperature starting circuit of the present invention is working, by judging whether the temperature of the thermistor measured for the first time is within the set range and whether the temperature value measured later increases, it is judged whether the electronic thermometer is in contact with the ambient temperature or the human body temperature, and then it is judged whether to directly enter the stability judgment stage, improving the accuracy of the display result of the electronic thermometer.

[0021] Specifically, in this embodiment, as Figure 2 shown, the resistance measurement control unit 1 includes an inverter INV4, D flip-flops DFF2, DFF3, DFF4, a NOR gate NOR1 and a NOR gate NOR2; The input terminal of inverter INV4 is used to input the all-display end signal AllDisEnd, where the all-display end signal AllDisEnd is provided by the original circuit of the electronic thermometer, that is, a low-level all-display end signal AllDisEnd is generated after the end of the all-display stage. The output terminal of inverter INV4 is electrically connected to the D input terminal of D flip-flop DFF2, and the Q output terminal of D flip-flop DFF2 is electrically connected to the D input terminal of D flip-flop DFF3; The two input terminals of NOR gate NOR1 are respectively electrically connected to the QN output terminal of D flip-flop DFF2 and the Q output terminal of D flip-flop DFF3. The output terminal of NOR gate NOR1 is used to output the measurement signal RF1st; The two input terminals of NOR gate NOR2 are respectively electrically connected to the QN output terminal of D flip-flop DFF3 and the Q output terminal of D flip-flop DFF4. The output terminal of NOR gate NOR2 is used to output the measurement signal RS1st; The CP terminals of D flip-flop DFF2, D flip-flop DFF3, and D flip-flop DFF4 are used to input the clock signal; The CDN terminals of D flip-flop DFF2, D flip-flop DFF3, and D flip-flop DFF4 are used to input the reset signal RESET.

[0022] In this embodiment, the clock signal is generated by dividing the system clock OSC of the electronic thermometer. Among them, the system clock OSC is 32.768KHz, and the clock signal is generated after being divided by the system clock 32768 times. In this way, the period of the clock signal input to the CP terminals of D flip-flop DFF2, D flip-flop DFF3, and D flip-flop DFF4 is 1s. In a certain implementation manner, the system clock OSC can select other frequencies, and the specific division ratio can also be other values, which are not limited here.

[0023] In this embodiment, Figure 2 The working process of the shown circuit is as follows: After the all-display stage of the electronic thermometer ends, the low-level all-display end signal AllDisEnd first becomes a high-level signal after passing through inverter INV4, and then passes through three-stage D flip-flops, namely D flip-flop DFF2, D flip-flop DFF3, and D flip-flop DFF4. The outputs of the D flip-flops generate the measurement signal RF1st and the measurement signal RS1st with a pulse width of 1s through logical combination. Both the measurement signal RF1st and the measurement signal RS1st are pulse signals, and the specific process is as follows: After the electronic thermometer runs for 2 s, the all-display end signal AllDisEnd becomes valid and starts to be sent into the D flip-flop DFF2. Since the D flip-flop DFF2 has a 1 s clock cycle, the outputs of the D flip-flops DFF2, DFF3, and DFF4 are all delayed by 1 s. That is, the Q terminal of the D flip-flop DFF2 goes high at 3 s, the Q terminal of the D flip-flop DFF3 goes high at 4 s, and the Q terminal of the D flip-flop DFF4 goes high at 5 s. The QN terminal of the D flip-flop DFF2 and the Q terminal of the D flip-flop DFF3 are connected to the input terminals of the NOR gate NOR1 to generate the measurement signal RF1st of the first measurement reference resistor, which is high from 3 to 4 seconds and has a pulse width of 1 s. The QN terminal of the D flip-flop DFF3 and the Q terminal of the D flip-flop DFF4 generate the measurement signal RS1st of the first measurement thermistor through the NOR gate NOR2. The measurement signal RS1st is high from 4 to 5 seconds and also has a pulse width of 1 s. The measurement signal RF1st for measuring the reference resistor can make the LCD screen display the self-check temperature of 37 °C / 98.6 °F after the measurement ends. After the end of the self-check stage, the measurement signal RS1st is used to start the process of measuring the temperature value of the first measurement thermistor.

[0024] Specifically, in this embodiment, the circuit of the temperature judgment unit 2 is as Figure 3 shown, including the NOR gate NOR3, the NOR gate NOR4, the NOR gate NOR5, the AND gate AND3, the AND gate AND4, the AND gate AND5, the AND gate AND6, the OR gate OR2, and the NAND gate NAND1; The two input terminals of the NOR gate NOR3, the two input terminals of the NOR gate NOR4, the two input terminals of the NOR gate NOR5, the two input terminals of the AND gate AND6, one input terminal of the AND gate AND3, and one input terminal of the AND gate AND4 are used to input the BCD code corresponding to the temperature measured by the thermistor; the output terminal of the NOR gate NOR3 is electrically connected to the other input terminal of the AND gate AND3, the output terminal of the NOR gate NOR4 is electrically connected to the other input terminal of the AND gate AND4, and the output terminal of the NOR gate NOR5, the output terminal of the AND gate AND6, and the two input terminals of the AND gate AND5 are electrically connected; The output terminals of the AND gate AND3 and the AND gate AND4 are electrically connected to the two input terminals of the OR gate OR2, the output terminal of the OR gate OR2, the output terminal of the AND gate AND5, and the two input terminals of the NAND gate NAND1 are electrically connected, and the output terminal of the NAND gate NAND1 outputs the judgment signal TP.

[0025] It should be noted that the BCD code is a method of representing a decimal value with a four-bit binary code. Since the body temperature measured by the electronic thermometer is a two-digit number, there are a total of eight binary numbers.

[0026] In this embodiment, the number of bits of the BCD code corresponding to the temperature measured by the thermistor input to the two input terminals of NOR gate NOR3, the two input terminals of NOR gate NOR4, the two input terminals of NOR gate NOR5, the two input terminals of AND gate AND6, one input terminal of AND gate AND3, and one input terminal of AND gate AND4 are different, resulting in different temperature judgment intervals.

[0027] Exemplarily, in this embodiment, the third bit CNT_One[2] and the fourth bit CNT_One[3] of the BCD code corresponding to the units digit of the temperature measured by the thermistor are input to the two input terminals of NOR gate NOR3; The second bit CNT_One[1] of the BCD code corresponding to the units digit of the temperature measured by the thermistor is input to one input terminal of AND gate AND3; The second bit CNT_One[1] and the fourth bit CNT_One[3] of the BCD code corresponding to the units digit of the temperature measured by the thermistor are input to the two input terminals of NOR gate NOR4; The third bit CNT_One[2] of the BCD code corresponding to the units digit of the temperature measured by the thermistor is input to one input terminal of AND gate AND4; The third bit CNT_Tne[2] and the fourth bit CNT_Tne[3] of the BCD code corresponding to the tens digit of the temperature measured by the thermistor are input to the two input terminals of NOR gate NOR5; The first bit CNT_Tne[0] and the second bit CNT_Tne[1] of the BCD code corresponding to the tens digit of the temperature measured by the thermistor are input to the two input terminals of AND gate AND6; For the connection method of the BCD code corresponding to the temperature measured by the above thermistor, the 4 signals of the tens digit of the BCD code corresponding to the temperature measured by the thermistor are screened out for the number 3 instead of 4 through AND gate AND5, AND gate AND6, and NOR gate NOR5. The 4 signal lines of the units digit of the BCD code corresponding to the temperature measured by the thermistor are divided into two groups. One group screens out the numbers 2 and 3 through AND gate ADN3 and NOR gate NOR3, and the other group screens out the numbers 4 and 5 through AND gate AND4 and NOR gate NOR4. The two groups of signals form an interval of numbers 2 to 5 through OR gate OR2. The above tens digit signal and units digit signal finally generate a low-level valid signal of 32 °C to 35 °C through NAND gate NAND1 to control the temperature judgment range of the starting point algorithm.

[0028] Specifically, in this embodiment, as Figure 4 shown, the LCD refresh signal generation unit 3 includes a numerical comparison unit 30, an OR gate OR3, an OR gate OR4, an AND gate AND6, and an RS flip-flop SR1; The numerical comparison unit 30 is used to compare the temperature measured by the thermistor with the stored memory temperature of the electronic thermometer, and input a high-level signal to one input terminal of the OR gate OR3 after the temperature measured by the thermistor is greater than the memory temperature. The two input terminals of the OR gate OR4 are used to input the measurement signal RF1st and the measurement signal RS1st. The output terminal of the OR gate OR4 is electrically connected to the other input terminal of the OR gate OR3. The output terminal of the OR gate OR3 is electrically connected to the S input terminal of the RS flip-flop SR1; The R input terminal of the RS flip-flop SR1 is used to input the signal RSBeg. The signal RSBeg is the pulse signal at the start of each measurement of the thermistor of the electronic thermometer. The Q output terminal of the RS flip-flop SR1 is electrically connected to one input terminal of the AND gate AND6. The other input terminal of the AND gate AND6 is used to input the signal RSEnd. The signal RSEnd is the pulse signal generated after each measurement of the thermistor of the electronic thermometer ends. The CDN terminal of the RS flip-flop SR1 is used to input the reset signal RESET. The output terminal of the AND gate AND6 is used to output the LCD refresh signal.

[0029] It should be noted that after the electronic thermometer completes the self-check stage (measuring the reference resistance twice in a row), it will continuously measure the reference resistance for 0.5s and the thermistor for 0.5s. The signal RSBeg is the start narrow pulse signal for each measurement of the thermistor, and the signal RSEnd is the narrow pulse signal after each measurement of the thermistor is completed.

[0030] In actual use, after the electronic thermometer goes through the full display stage and the display memory temperature stage, the LCD refresh signal controls the screen of the electronic thermometer to update the self-check temperature of 37°C / 98.6°F and the temperature value of the measured reference resistance; the numerical comparison unit is used to compare the memory temperature stored in the electronic thermometer with the temperature value of the internal current-measured thermistor. Only after the measured temperature value of the thermistor is greater than the memorized temperature value, the screen is allowed to update the temperature of this measurement; For Figure 4 Analyze the circuit shown as follows. First, the measurement signal RF1st is a pulse signal with a pulse width of 1s from 3s to 4s, and the measurement signal RS1st is a pulse signal with a pulse width of 1s from 4s to 5s. The measurement signal RF1st and the measurement signal RS1st can shield the signal sent by the numerical comparison unit 30 through the OR gate OR4 and the OR gate OR3. That is, during the self-check stage (3s to 4s) and the first measurement of the thermistor stage (4s to 5s) of the electronic thermometer, the S terminal of the RS latch SR1 is always at a high level, the Q terminal of the RS latch SR1 is also always at a high level, the enable terminal of the LCD refresh signal is always open, and the LCD can update the self-check temperature of 37°C / 98.6°F and the temperature value of the first measurement of the thermistor; Immediately afterwards, during the subsequent measurement of the thermistor, the narrow pulse signal of signal RSBeg is first sent to the R terminal of RS latch SR1, resetting the Q terminal of RS latch SR1, which means closing the enable terminal of the LCD refresh signal. After waiting for the measurement of the thermistor to end, if the temperature value measured inside the electronic thermometer is greater than the recorded temperature value, the S terminal of RS latch SR1 is set, and the Q terminal of RS latch SR1 is also set, which is equivalent to opening the enable terminal of the LCD, and then the RSEnd signal indicating the end of the measurement will update the LCD; If the temperature value measured inside the electronic thermometer is less than or equal to the recorded temperature value, the S terminal of RS latch SR1 is not effective, and the enable terminal of the LCD refresh is always turned off, so the LCD cannot be updated, that is, the highest temperature value measured previously will still be displayed on the screen, and the temperature value of the currently measured lower thermistor will not be updated.

[0031] In addition, for Figure 1 the logic devices in, when the electronic thermometer is in the stage of measuring the reference resistor for the first time, the measurement signal RF1st is at a high level, and after passing through the inverter INV3, AND gates AND1 and AND2, the LCD refresh signal at this time will be blocked. When the electronic thermometer is in the stage of the first measurement, the measurement signal RS1st is at a high level. If the temperature of the measured thermistor is within the temperature range, that is, within the temperature range of the temperature judgment unit, the signal sent to the OR gate OR1 is at a low level, and after passing through the AND gates AND1 and AND2, the LCD refresh signal at this time will also be blocked; On the contrary, if the temperature of the measured thermistor is not within the temperature range, the signal sent to the OR gate OR1 is at a high level, and after passing through the AND gate AND1, it remains high, which is equivalent to opening the control terminal of the LCD refresh signal, and the LCD refresh signal can be sent to the CP terminal through the AND gate AND2; After the first measurement of the thermistor ends, the CP signal is directly connected to the LCD refresh signal and changes with the LCD refresh signal.

[0032] Figure 5 is the timing diagram of the relevant signals when the circuit in this embodiment actually works. From Figure 5It can be obtained that the LCD refresh signal LCDRefresh used to update the screen value after the memory temperature display stage will only form a narrow pulse signal after the first measurement of the reference resistor, the first measurement of the thermistor, and the subsequent measurement of the thermistor with increasing temperature. According to the circuit design, when the temperature value of the first measurement of the thermistor is within the temperature range of the starting circuit, the LCD refresh signal will not be sent to the CP terminal of the D flip-flop DFF1; only when the temperature of the measured thermistor is higher than the temperature value of the first measured thermistor, the LCD refresh signal will arrive, and the electronic thermometer will enter the stability judgment stage from the starting stage.

[0033] Embodiment 2 This embodiment provides an electronic thermometer, including the temperature starting circuit in Embodiment 1.

[0034] Embodiment 3 This embodiment provides a temperature measurement method, which is implemented by the electronic thermometer in Embodiment 2. The steps of the electronic thermometer for temperature measurement are as follows: S1: The electronic thermometer starts for full display; S2: The electronic thermometer displays the memory temperature; S3: The electronic thermometer displays 37°C or 98.6°F; S4: The electronic thermometer displays the temperature of the first measured thermistor; S5: Determine whether the temperature of the measured thermistor is within the starting algorithm temperature range. If it is within the range, execute step S6; otherwise, execute step S7; S6: Determine whether the measured temperature is increasing. If the temperature is increasing, execute step S7; otherwise, return to step S4; S7: The electronic thermometer enters the stability judgment stage.

[0035] Specifically, in combination with Figure 5 , when the high-level effective measurement signal RF1st is generated, the high-level effective measurement signal RF1st becomes low after passing through the inverter INV3, and then after passing through the AND gates AND1 and AND2, the CP terminal of the D flip-flop DFF1 is pulled low, and the D flip-flop DFF1 does not work. This is equivalent to shielding the CP signal of the D flip-flop DFF1 in the self-check stage, and the electronic thermometer will not enter the stability judgment stage; After the self-check stage, the electronic thermometer is in the stage of measuring the thermistor for the first time. The high-level effective measurement signal RS1st enters the OR gate OR1 after passing through the inverter INV1. If the temperature value measured on the thermistor at this time is not within the temperature range of the starting point algorithm, the signal sent to the other input terminal of the OR gate OR1 through the inverter INV2 is high level, and the output of the OR gate OR1 is high level, which is sent into the AND gate AND1. Since the electronic thermometer has passed the time of the self-check stage at this time, the measurement signal RF1st is low level, and the output is high level after passing through the inverter INV3, and is sent into the AND gate AND1. At this time, the high level output by the AND gate AND1 enters the AND gate AND2, which is equivalent to enabling the LCD refresh signal to enter the CP terminal of the D flip-flop DFF1. When the first measurement of the thermistor is completed, the narrow pulse LCD refresh signal will be allowed to pass through the AND gate AND2 and be sent to the CP terminal of the D flip-flop DFF1. The reset signal of the D flip-flop DFF1 is the system reset signal RESET composed of POR and the key switch. When there is a rising edge at the CP terminal, the Q terminal outputs a high level, and the electronic thermometer enters the stability judgment stage.

[0036] On the contrary, if the temperature value of the first measurement of the thermistor is within the temperature range of the starting point algorithm, the signal sent to one end of the OR gate OR1 through the inverter INV2 is low level. At this time, both inputs of the OR gate OR1 are low level, and the output of the OR gate OR1 is also low level. After passing through the AND gates AND1 and AND2, the signal sent to the CP terminal of the D flip-flop DFF1 is also low level, and the D flip-flop DFF1 will not work. This is equivalent to shielding the CP signal of the D flip-flop DFF1 in the first thermistor measurement stage, and the electronic thermometer will not enter the stability judgment stage.

[0037] After the stage of first measuring the temperature value of the thermistor ends, the electronic thermometer is either in the starting stage of cyclic judgment or working in the measurement stage where stability can be judged. In the starting stage, if the measured temperature value of the thermistor is the same as the temperature value of the thermistor in the first measurement and remains unchanged all the time, the LCD refresh signal will not be valid and will always be at a low level, and the electronic thermometer will still be in the starting stage. If the measured temperature value of the thermistor is higher than the temperature value of the thermistor in the first measurement, the LCD refresh signal will send a corresponding narrow pulse signal. Since the thermometer has passed the self-check stage and the stage of first measuring the thermistor at this time, both the measurement signal RF1st and the measurement signal RS1st are at a low level. The measurement signal RS1st becomes high level after passing through the inverter INV1 and is sent into the OR gate OR1. The output of the OR gate OR1 is high level and is sent to the AND gate AND1. The measurement signal RF1st becomes high level after passing through the inverter INV3 and is also sent into the AND gate AND1. At this time, the high level output by the AND gate ADN1 will cause the LCD refresh signal to pass through the AND gate AND2. The CP terminal of the D flip-flop DFF1 receives a rising edge signal, and the Q terminal outputs a high level, and the thermometer enters the stability judgment stage from the starting stage.

[0038] In addition, in this embodiment, the interval endpoint values of the starting point algorithm temperature interval are adjustable. Based on the inspiration of the present invention, through the above description, relevant staff can completely make various changes and modifications without departing from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. Temperature starting circuit for electronic thermometer, characterized in that, It includes a resistance measurement control unit, a temperature judgment unit, an LCD refresh signal generation unit, an inverter INV1, an inverter INV2, an inverter INV3, an OR gate OR1, an AND gate AND1, an AND gate AND2, and a D flip-flop DFF1; The resistance measurement control unit generates a measurement signal RF1st and a measurement signal RS1st based on the input full display end signal. The measurement signal RS1st is later than the measurement signal RF1st. The measurement signal RF1st is used to start the reference resistance measurement of the electronic thermometer, and the measurement signal RS1st is used to start the thermistor measurement of the electronic thermometer; The temperature judgment unit is used to judge whether the temperature measured by the thermistor is within the set range and outputs a judgment signal TP based on the judgment result; The LCD refresh signal generation unit is used to judge the temperature on the thermistor and generate an LCD refresh signal based on the judgment result, the measurement signal RF1st, and the measurement signal RS1st; The measurement signal RS1st is input to the inverter INV1, the judgment signal TP is input to the inverter INV2, the measurement signal RF1st is input to the inverter INV3. The output terminals of the inverter INV1 and the inverter INV2 are electrically connected to the two input terminals of the OR gate OR1. The output terminal of the OR gate OR1, the output terminal of the inverter INV3, and the two input terminals of the AND gate AND1 are electrically connected. The two input terminals of the AND gate AND2 are respectively connected to the input terminal of the AND gate AND1 and the LCD refresh signal output terminal of the LCD refresh signal generation unit. The output terminal of the AND gate AND2 is connected to the CP terminal of the D flip-flop DFF1. The CDN terminal of the D flip-flop DFF1 is used to input a reset signal RESET. The Q output terminal of the D flip-flop DFF1 is used to output an enable signal EnStaTime, and the enable signal EnStaTime is used to make the electronic thermometer enter the stability judgment stage.

2. The temperature starting circuit for an electronic thermometer according to claim 1, wherein The resistance measurement control unit includes an inverter INV4, a D flip-flop DFF2, a D flip-flop DFF3, a D flip-flop DFF4, a NOR gate NOR1, and a NOR gate NOR2; The input terminal of the inverter INV4 is used to input the full display end signal. The output terminal of the inverter INV4 is electrically connected to the D input terminal of the D flip-flop DFF2. The Q output terminal of the D flip-flop DFF2 is electrically connected to the D input terminal of the D flip-flop DFF3; The two input terminals of the NOR gate NOR1 are respectively connected to the QN output terminal of the D flip-flop DFF2 and the Q output terminal of the D flip-flop DFF3. The output terminal of the NOR gate NOR1 is used to output the measurement signal RF1st; The two input terminals of the NOR gate NOR2 are respectively connected to the QN output terminal of the D flip-flop DFF3 and the Q output terminal of the D flip-flop DFF4. The output terminal of the NOR gate NOR2 is used to output the measurement signal RS1st; The CP terminals of the D flip-flop DFF2, the CP terminal of the D flip-flop DFF3, and the CP terminal of the D flip-flop DFF4 are used to input a clock signal; The CDN terminals of the D flip-flop DFF2, the CDN terminal of the D flip-flop DFF3, and the CDN terminal of the D flip-flop DFF4 are used to input a reset signal RESET.

3. The temperature starting circuit for an electronic thermometer according to claim 2, characterized in that, The clock signal is generated by dividing the system clock of the electronic thermometer.

4. The temperature starting circuit for an electronic thermometer according to claim 3, characterized in that, The system clock is 32.768 KHz, and the clock signal is generated after dividing the system clock by 32768.

5. The temperature starting circuit for an electronic thermometer according to claim 1, characterized in that The temperature judgment unit includes a NOR gate NOR3, a NOR gate NOR4, a NOR gate NOR5, an AND gate AND3, an AND gate AND4, an AND gate AND5, an AND gate AND6, an OR gate OR2, and a NAND gate NAND1; The two input terminals of the NOR gate NOR3, the two input terminals of the NOR gate NOR4, the two input terminals of the NOR gate NOR5, the two input terminals of the AND gate AND6, one input terminal of the AND gate AND3, and one input terminal of the AND gate AND4 are used to input the BCD codes corresponding to the temperatures measured by the thermistor; the output terminal of the NOR gate NOR3 is electrically connected to the other input terminal of the AND gate AND3, the output terminal of the NOR gate NOR4 is electrically connected to the other input terminal of the AND gate AND4, and the output terminals of the NOR gate NOR5, the AND gate AND6, and the two input terminals of the AND gate AND5 are electrically connected; The output terminals of the AND gate AND3, the AND gate AND4, and the two input terminals of the OR gate OR2 are electrically connected, the output terminal of the OR gate OR2, the output terminal of the AND gate AND5, and the two input terminals of the NAND gate NAND1 are electrically connected, and the output terminal of the NAND gate NAND1 outputs the judgment signal.

6. The temperature starting circuit for an electronic thermometer according to claim 5, characterized in that, The third and fourth bits of the BCD code corresponding to the units digit of the temperature measured by the thermistor are input to the two input terminals of the NOR gate NOR3; The second bit of the BCD code corresponding to the units digit of the temperature measured by the thermistor is input to one input terminal of the AND gate AND3; The second and fourth bits of the BCD code corresponding to the units digit of the temperature measured by the thermistor are input to the two input terminals of the NOR gate NOR4; The third bit of the BCD code corresponding to the units digit of the temperature measured by the thermistor is input to one input terminal of the AND gate AND4; The third and fourth bits of the BCD code corresponding to the tens digit of the temperature measured by the thermistor are input to the two input terminals of the NOR gate NOR5; The first and second bits of the BCD code corresponding to the tens digit of the temperature measured by the thermistor are input to the two input terminals of the AND gate AND6.

7. The temperature starting circuit for an electronic thermometer according to claim 1, characterized in that The LCD refresh signal generation unit includes a numerical comparison unit, an OR gate OR3, an OR gate OR4, an AND gate AND6, and an RS flip-flop SR1; The numerical comparison unit is used to compare the temperature measured by the thermistor with the stored memory temperature of the electronic thermometer, and input a high-level signal to one input terminal of the OR gate OR3 after the temperature measured by the thermistor is greater than the memory temperature. The two input terminals of the OR gate OR4 are used to input the measurement signal RF1st and the measurement signal RS1st. The output terminal of the OR gate OR4 is electrically connected to the other input terminal of the OR gate OR3. The output terminal of the OR gate OR3 is electrically connected to the S input terminal of the RS flip-flop SR1; The R input terminal of the RS flip-flop SR1 is used to input the signal RSBeg. The signal RSBeg is the pulse signal at the start of each measurement of the thermistor of the electronic thermometer. The Q output terminal of the RS flip-flop SR1 is electrically connected to one input terminal of the AND gate AND6. The other input terminal of the AND gate AND6 is used to input the signal RSEnd. The signal RSEnd is the pulse signal generated after each measurement of the thermistor of the electronic thermometer ends. The CDN terminal of the RS flip-flop SR1 is used to input the reset signal RESET. The output terminal of the AND gate AND6 is used to output the LCD refresh signal.

8. An electronic thermometer, characterized in that, Comprising the temperature starting circuit according to any one of claims 1-7.

9. A temperature measurement method, characterized in that, Implemented by the electronic thermometer according to claim 8. The steps of the electronic thermometer for temperature measurement are as follows: S1: The electronic thermometer starts and displays fully. S2: The electronic thermometer displays the memory temperature. S3: The electronic thermometer displays 37°C or 98.6°F. S4: The electronic thermometer displays the temperature of the thermistor measured for the first time. S5: Determine whether the temperature of the measured thermistor is within the starting point algorithm temperature range. If it is within the range, execute step S6; otherwise, execute step S7. S6: Determine whether the measured temperature is rising. If the temperature is rising, execute step S7; otherwise, return to step S4. S7: The electronic thermometer enters the stability judgment stage.

10. The temperature measurement method according to claim 9, wherein The endpoint values of the starting point algorithm temperature range are adjustable.

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