SU1125478A1 - Digital thermometer - Google Patents

Abstract

DIGITAL THERMOMETER contained (IC thermocouple with frequency output connected to the first input of the mixer, the output of which is connected to the first input of the first circuit AND, and the second input connected to the input of the time base counter, setting input which is connected to the first output of the control circuit, and the outputs through the first switching element are connected to the coincidence circuit, the output of which is connected to the first input of the control circuit, the second output of which is connected to the second input of the first And the third output - with the installation input in the position O of the measurement result counter and the installation input in position 1 of the sign trigger, the counting input of which is connected to the transfer output of the measurement result counter, and the fourth output of the control circuit is connected with the clock input of the display register, whose inputs connected to the outputs of the result counter and the sign trigger, and the output through the code converter is connected to the input of the display unit, the second switching element and the second AND circuit, characterized in that, in order to simplify the calibration process, a thermometer, a frequency divider with a tunable division factor and an additional counter, the outputs of which are connected to the installation inputs of the result counter, are entered, the installation input in the O position is connected to the fifth output of the control circuit, and the input is connected to the output of the second circuit I, inputs which are respectively connected to the second output of the control circuit and to the output of 1 9 SP 4 home houses with a tunable division factor, the installation inputs of which are connected to the output of the second switching element The input is connected to the reference frequency generator, npw this three intermediate outputs of the time base counter are connected to the second, third and fourth inputs of the control circuit, the sixth output of which is connected to the installation input of the result counter. .

Description

1 1 The invention relates to the field of temperature measurements and can be used in the construction of digital thermometers, operating in a composition with thermal converters that have a frequency output, for example, piezoquartz temperature sensors. A device for temperature measurement is known, which contains a temperature output temperature transducer connected to a key input, a reference frequency generator connected to a frequency divider, a control unit whose input is connected to higher-level outputs of a frequency divider, and outputs connected to a key control input, reference generator Frequency- and the input of the installation of the tel frequency, the display unit. However, this device is characterized by the inconvenience of its graduation due to its structural scheme. The closest in technical essence to the invention is a digital thermometer containing a thermal output transducer connected to the first input of the mixer, the output of which is connected to the first input of the first cxe№i I, and the second input is connected to the output of the reference frequency generator, the Id input with the input of the time base counter, the installation input of which is connected to the first output. control, and the outputs through the first switching element are connected to the same circuit, g (the output of which is connected to the first input of the control circuit, the second output of which is connected to the second input of the first AND circuit, the third output to the installation input O of the measurement result counter and the installation of the input in 1 sign trigger, the counting input of which is connected to the transfer output of the measurement result counter, and the fourth output of the control circuit - to the clock input of the display register, whose inputs are connected to the outputs of the result counter and trigger ka, and the outputs through the code converter are connected to the input of the display unit, the second switching element and the second circuit AND 2 However, the known digital thermometer is characterized by the inconvenience of its calibration due to its building structure. 2 The purpose of the invention is to simplify the calibration process of the digital thermometer by introducing separate calibration 6, and e g (for example, 9 liters of UOS). The goal is achieved by the fact that a digital thermometer containing a temperature converter with a frequency output connected to the first input an output whose output is connected to the first input of the first I circuit, and a second input connected to the output of the reference frequency generator, connected to the input of a time base counter, whose setup input is connected to the first output of the control circuit, and the outputs through the first switching element are connected to the coincidence circuit, the output of which is connected to the first input of the control circuit, the second output of which is connected to the second input of the first I circuit, the third output to the installation input in O of the measurement result counter and the installation input to 1 sign trigger, sec The second input of which is connected to the transfer output of the measurement result counter, and the fourth output of the control circuit is connected to the clock input of the display register, the inputs of which are connected to the outputs of the result counter and the sign trigger, and the output through the code converter are connected to the input of the display unit, the second switching element and the second circuit And, introduced a frequency divider with a tunable division factor and an additional counter, the outputs of which are connected to the installation inputs of the result counter, the input set In O, it is connected to the fifth output of the control circuit, and the input is connected to the output of the second circuit AND, the inputs of which are respectively connected to the second input of the control circuit and the output of the divider with a tunable 1m dividing factor, the set inputs of which are connected to the output of the second switching element, and the input is connected to a reference frequency generator, while the three intermediate outputs of the time base counter are connected to the second, third and fourth inputs of the control circuit, the sixth output of which is connected to the installation input of the counter result. FIG. 1 is a block diagram of the digital thermometer j in FIG. 2 control circuit; in fig. 3 - time I diagrams that explain the operation of a digital thermometer. The digital thermometer contains a thermocouple converter 1 with a frequency output, a generator 2 of the reference frequency, a mixer 3, a divider 4 frequencies with a tunable division factor, switching element 5, two circuits AND 6 and 7, a control circuit 8, a coincidence circuit 9, a switching element 10, a counter 11 time base, additional counter 12, result counter 13, trigger 14 characters, display register 15, controllable code converter 16, display unit 17, with inputs 18–20 of the control circuit connected to intermediate outputs of the counter base for short, and Control circuit 21 in a yield soEladeni circuit. The output 22 of the control circuit is connected to the second inputs of the circuits 6 and 7, the output 23 to the installation input to the additional counter 12, the output 24 to the installation input of the result counter 13, the output 25 to the installation input to the result counter 13 and the installation input in 1 flip-flop 14 characters, output 26 - with a ticking input of register 15 of the indication and output 21 - with an installation input in O of the time base counter 11. The control circuit 8 comprises three inverters 28-30, six AND 31-36 circuits and a trigger 37, moreover, the input of the inverter 28 is connected to the input 18, the output of which is connected to the first inputs of the AND circuits 31, 33 and 35, and the second inputs of the circuits 32 and 34. Input 19 is connected to the second input of the AND 33 circuit, the third input of the AND 3 circuit and the input of the inverter 29, the output of which is connected to the second inputs of the And 31 and 35 circuits and the first input of the And 32 circuit. Input 20 is connected to the input of the inverter 30, output which is connected to the third inputs of the circuits And 31-33 and the first input of the circuit And 34, and to the third input of the circuit And 35, connected by its output to the input set to 1 flip-flop 37. Input 21 of the control circuit is connected to the first input of the AND 36 circuit and input of the installation to O of the flip-flop 37, the inverse of the HbBJ output of which is connected to the fourth inputs of the And 31-35 circuits and the second input of the And 36 circuit whose output is connected to exit 27. 8g; Outputs 23-26 of the control circuit are respectively connected to the outputs of the AND circuits 34-31 and output 22 to the direct input of trigger 37. The digital thermometer operates as follows. Mixer 3 extracts a signal whose frequency is equal to the frequency difference between temperature sensor 1 and frequency generator 2, the last of which is chosen less than the minimum frequency of thermal converter 1, as a result of which the sign of the difference of both frequencies in the entire temperature measurement range remains unchanged. The frequency of the oscillator 2 reference frequency divider 4 frequency with a tunable division factor using the commutating element 5 is converted into a frequency equal to the frequency of the output signal of the mixer 3 at a sensor temperature equal to 0 ° C. The pulses of the oscillator 2 of the reference frequency, which also arrive at the counting input of the time base counter 11, are converted by the switching element 10, the coincidence circuit 9 and the control circuit 8 into a series of signals shown in FIG. 3cx - Assuming that at time L (j (j, 3 "), the trigger 37 of the control circuit 8 and the first three outputs of the time base counter 11 connected to the inputs 18-20 of the control circuit B, respectively, are in the zero state, the output of the circuit And a positive pulse is generated through the output 26 of the control circuit 8 to the clock input of the display register 15, under the influence of which the state of the result counter 13 and the character trigger 14 is written to it. This increases by one, with the result that at the output of the AND circuit 32 of the control circuit 8 a positive pulse is generated (FIG. 36, time t) received through the output 25 of the control circuit 8 to the installation input in O of the result counter 13 and to the installation input to 1 the trigger of the 14th sign. Under the influence of the next pulse of the reference frequency generator 2, the state of the time base counter is increased again by one, and a positive pulse is formed at the output of the control circuit 33 of the control circuit (Fig. 8). Zv, time t2) is supplied via the output 24 of the control circuit 8 to the input of the installation of the result counter 13, as a result of which the contents of the additional counter 12 are recorded (Fig. 3 "j, i). In the following tact, at the output of the circuit AND 34 of the control circuit 8 forms: a positive pulse (11) ig. Zj.jMoneHT time tj), under the influence of which, through the output 23 of the control circuit 8, the additional counter 12 is set to the state O. Under the influence of the positive pulse to the input of the installation of 1 trigger that occurs in the next clock output of the circuit AND 35 of the circuit 8 37 of the control circuit 8 at its direct output is set noJio; KH the potential potential (Fig. Ze, moment of time) This signal goes through control output 22 cxeiviw 8 to the second inputs of the circuits 6 and 7 and thereby enables the counting of pulses from the output of the mixer 3 in the counter 13 rezat tata, operating in the forward counting mode, and pulse counting from the output of the 4 frequency divider with a tunable division factor in the additional counter 12, operating in the countdown mode. When the base 11 reaches the time base, the state corresponds to the value set by the switching element 10. schemes of coincidence 9 form a positive impulse (fig. DZ, time i,), acting through the input 21 of the control circuit 8, the installation input into the O flip-flop 37, and the second input of the circuit 36 of the control circuit 8, resulting in a zero. your sweat ntsiala on the forward trigger output. 37, coming through the control circuit output 22 to the second inputs of the And 6 and 7 circuits, the counting of pulses is stopped in both the counter 13 of the result and the auxiliary counter 12 ,. and because of the positive potential, a positive impulse occurs at the inverse output of the trigger 37 at the output of the circuit AND 36 of the control circuit 8 (Fig. 3, time tg), acting through the output 27 of the control circuit 8 to the input of the time base counter 11. By setting the counter 11 of the time base in O, the start: mc is the next measurement cycle (Fig. 3, time point t). The separate adjustment of the digital thermometer is that the installation of the switching element 5 implements such a division factor of the 4 frequency divider that its output frequency exactly corresponds to the frequency at the output of the mixer 3 at the sensor 1 temperature equal to 0 ° C. As a result, the number of pulses arriving at counter 13 and the additional counter 12 at the zero temperature of sensor 1 are identical. Taking into account the countdown mode of the additional counter 12 after entering its contents into the account-. 13 of the result (Fig. 3g, time instant -to) and the subsequent counting of pulses from the output of the mixer 3 during the time interval in the counter 13 of the result operating in the direct counting mode, is accumulated. a number equal to its maximum capacity, represented in the form of a transfer, setting the trigger 14 c.-1 to the zero state, and the zero state of the result counter 13 itself. The zero reading obtained in this case on the display block 17 of the digital thermometer does not depend on the randomly set length of the time interval, the exact value of which at this stage of calibration is not yet known. The installation of the switching element 10 determines that. the state of the time counter 11, on reaching which at the output of the coincidence circuit 9 there arises a positive pulse (Fig. 3d, time tg), ending the counting time of both the result counter and auxiliary counter 12. Providing the temperature of the second reference point on the thermal conversion I changing the setting of the switching element 10, we realize the duration of the time interval leading to the indication on the display unit 17 of the digital thermometer of the temperature of the second reference point without changing the setting element 5. Thus, the separate adjustment. Digital Thermometer Proizvgps in dvzts stages. At the first stage, the zero state is established with the help of the switching element 5.

a digital thermometer (the first reference point uses melting ice), and in the second stage changing the setting of the switching element 10 is achieved on the display unit 17 of the digital thermometer temperature of the second reference point.

The pulse frequency f at the output of the thermal converter 1, depending on the measured temperature 0, is equal to J,

(one)

.5 (e-ej

0 0 frequency of sensor output 1 where about 5 temperature is the slope of the thermal frequency response of the thermal converter in DB - calibration temperature. If the time interval 1 - 5 is denoted by Tg (time base), then the number accumulated by the time point 1 $ from the counter 13 of the result is equal to,. -.- and Scratch e- Pts) 2) the point / BV scvsp "frequency at the output of the generator 2 reference frequency ;; the contents of the additional counter 12 by the time t J (the previous measurement cycle). Moreover, the minus sign in the formula (2 takes into account the countdown mode of the additional counter 12, the content of which is determined by the ratio N –T с оч с в сп bv to (3) where K is the division factor of 4 times 4 defined by the setting of the switching element 5, After the first the adjustment phase of co. human beings is next {C5e is the ratio o-S6 .- .. ,,, Point to JUSTER, is the value of the divider ratio of 4 frequencies after the adjustment, taking into account that the content of the additional counter 12 is equal to T68 () (

Then the contents of the counter 13 result after the first stage of the adjustment is equal to

 Easyr ® BV

and at. really goes to zero.

After the second adjustment phase, the following additional relationship is observed.

(7)

2 BV adjust the temperature of the repetition point of the digital thermometer; the time base after the second BV adjustment adjustment, taking into account that the relation (6) takes the form 9c, midrange 2d0, the contents of the counter 13, which rests at 6, after the second adjustment, means that the digital device, after separate adjustment of the parameters K and Tdr actually shows the value of the measured temperature. The control transducer 16 of the code, with a single value of the sign bit of the display register 15, converts the input code into the reverse one, which ensures correctness the digital thermometer readings when measuring negative temperatures (E 0 ° C), otherwise the control converter 16 of the code does not affect the transmission of the code c. the output of the register 15 of the display to the inputs of the block 17 of the display. The presence of a frequency divider with a tunable coefficient in the proposed digital thermometer, and takdae new connections between the elements distinguishes it from the known, as it allows to simplify the process of its calibration and thereby simplify its operation.

Fig. /

(rig 2

  i / 3 / epffffi / ff

Claims (1)

A DIGITAL THERMOMETER containing a thermocouple with a frequency output connected to the first input of the mixer, the output of which is connected to the first input of the first circuit And, and the second input is connected to the output of the reference frequency generator connected to the input of the base time counter, the installation input of which is connected to the first the output of the control circuit, and the outputs through the first switching element are connected to the coincidence circuit, the output of which is connected to the first input of the control circuit, the second output of which is connected to the second input of the first circuit And, rety output - to an input of setting to "0" counter measurement result and the input set to 'to' H trigger mark, the count input of which is connected with the counter output transfer the measurement result, and a fourth output connected to the control circuit. clock input of the display register, the inputs of which are connected to the outputs of the result counter and the sign trigger, and the output through the code converter is connected to the input of the display unit, the second switching element and the second circuit And, characterized in that, in order to simplify the calibration process, the thermometer into it a frequency divider with a tunable division factor and an additional counter are introduced, the outputs of which are connected to the setting inputs of the result counter, the input of setting to position 0 is connected to the fifth output of the control circuit phenomena, and the input is connected to the output of the second circuit And, the inputs of which are respectively connected to the second output of the control circuit and the output of the divider with a tunable division factor, the installation inputs of which are connected to the output of the second switching element, and the input is connected to the reference frequency generator, with three intermediate the outputs of the base time counter are connected to the second, third and fourth inputs of the control circuit, the sixth output of which is connected to the installation input of the result counter. . SU.-, 1125478