RU2039953C1 - Digital thermometer - Google Patents

Abstract

FIELD: measurement technology. SUBSTANCE: digital thermometer has wider functional capabilities determined by use of multiplication-division operation with simultaneous realization of summing operation when reversible counter combines functions of frequency-to-time interval converter and storage and frequency-pulse sequences are commutated under control of time-pulse signals. EFFECT: widened functional capabilities. 2 dwg

Description

 The invention relates to temperature measurements and can be used in the construction of digital thermometers working with thermal converters having a frequency output signal, for example piezoelectric transducers.

 A known digital thermometer containing a temperature converter with a frequency output, a reference frequency generator, a counter, two switching elements, a matching circuit, a control circuit, a reversible display system, a sign trigger, a result counter, circuit I.

 The disadvantages of the known device are its complexity, due to its construction structure, and limited functionality.

 A known digital thermometer comprising a thermocouple with a frequency output, a counter, two switching elements, a circuit And, a result counter, a sign trigger, a reversible display system.

 The disadvantages of a digital thermometer are its complexity, due to its construction structure, and limited functionality.

 A known digital thermometer comprising a temperature converter with a frequency output, an offset frequency generator, a mixer, a counter, two switching elements, a matching circuit, a control circuit, an I circuit, a result counter, a sign trigger, a reversible indication system.

 The disadvantages of a digital thermometer are its complexity, due to its construction structure, and limited functionality.

 The closest in combination of features and in technical essence to the claimed technical solution is the well-known digital thermometer, which is adopted as a prototype and is shown in figure 1.

 The thermometer of the prototype (figure 1) contains a temperature converter 1 with a frequency output, the first 2 and second 3 frequency generators, a reverse counter 4, an element 5, a trigger 6, an indication unit 7, a frequency to code converter 8, a code to frequency converter 9, the frequency input of which is connected to the output of the second frequency generator 3, while the summing input of the reverse counter 4 is connected to the output of the element And 5, the first input of which is connected to the output of the trigger 6, and the output of the frequency converter 8 to the code is connected to the input of the display unit 7. In addition, the prototype contains a counter 10 and elements 11, 12, the outputs of which are connected respectively to the inputs of the frequency converter 8 to code and a counter 10, the output of which is connected to the reset input of trigger 6, the installation input of which is connected to the output of thermal converter 1, and its output combined with the first inputs of the elements And 11, 12, the second inputs of which are connected to the outputs of the code converter 9 to the frequency and the frequency generator 2, respectively, while the output of the code converter 9 is connected to the subtracting input of the reverse frequency a sensor 4 connected by an output to the code input of the code-to-frequency converter 9, the frequency input of which is connected to the second input of AND element 5.

где F(t) выходная частота термопреобразователя;
t температура;
а постоянный коэффициент;
Прототип работает следующим образом.The prototype runs continuously. It provides linearization of the characteristics of thermal converters with the dependence
F (t) = a

where F (t) is the output frequency of the thermal converter;
t temperature;
a constant coefficient;
The prototype works as follows.

Generators 2 and 3 frequencies produce pulse sequences with frequencies F ₁ and F _2, respectively, and the frequencies F ₁ and F ₂ must be much higher than the output frequency F (t) of the thermal converter 1.

The pulse from the output of the thermal converter 1, arriving at the input of the trigger 6, translates it into a single state. The signal from the output of the trigger 6 opens the elements And 5, 11, 12. Through the element And 12 to the input of the counter 10 starts to receive pulses from the generator 2, following with a frequency of F ₁ . After a time τ = k / F ₁ , where k is the division coefficient of the counter 10, it will overflow and a signal will be generated at its output, setting trigger 6 to the zero state. The next pulse from the output of the thermocouple 1 again puts the trigger 6 in a single state for a time τ. Thus, at the output of trigger 6, a train of pulses of duration τ is formed, followed by a frequency F (t).

During the time θ, which is much longer than the pulse repetition period from the thermal converter 1, NF ₂ ˙ τ ˙ F (t) θ pulses arrive at the summing input of the reversing counter 4 through the And 5 element. The output code of the reverse counter 4 is supplied to the inputs of the code converter 9 to the frequency, the pulse input of which has a pulse sequence with a frequency of F ₂ from the generator 3. The frequency signal from the output of the converter 9 is fed to the subtracting input of the reverse counter 4. In a steady state with a large conversion coefficient K _{9 of the} converter 9, the number of pulses arriving at the summing and subtracting inputs of the reverse counter for the time interval θ is equal to each other
F ₂ ˙ τ ˙ F (t) θ F ₉ ˙ θ where F _{9 is the} frequency of the pulse signal at the output of the code converter 9 to the frequency.

F²(t) импульсов, в результате чего код на выходе преобразователя 8 пропорционален квадрату частоты термопреобразователя. При выполнении условия F₂ ˙ K² ˙ θ / F₁ ² а выходной код N_x преобразователя 8 однозначно связан с измеряемой температурой N_x t. Этот код отражается цифровым индикатором блока 7 индикации.The frequency signal from the output of the Converter 9 is supplied through the element 11 to the input of the frequency Converter 8 in the code. For the time interval θ, determined by the design of the Converter 8, the input of the Converter 8 will
N _x

F ² (t) pulses, as a result of which the code at the output of the converter 8 is proportional to the square of the frequency of the thermal converter. Under the condition F ₂ ˙ K ² ˙ θ / F ₁ ² and the output code N _{x of the} converter 8 is uniquely associated with the measured temperature N _x t. This code is reflected by the digital indicator of the indication unit 7.

 The disadvantage of the prototype is its limited functionality, due to the presence of only multiple-dividing operations in the functional characteristics of the device.

 The essence of the proposed technical solution consists in creating a digital thermometer with wider functional capabilities, determined by the use of a multiplying-dividing operation while simultaneously performing the summing operation, by combining a frequency-time converter and a memory device with a reversible counter and switching pulse-frequency sequences under the control of time-pulse signals .

 The essential features of the claimed invention are that in a digital thermometer comprising a converter with a frequency output, a first and second frequency generators, a reversible counter, an I element, a trigger, an indication unit, a frequency to code converter, a code to frequency converter, the frequency input of which is connected with the output of the second frequency generator, while the summing input of the reverse counter is connected to the output of the element And, the first input of which is connected to the output of the trigger, and the output of the frequency converter to the code is connected to input By the indication block input, a commutator, a third frequency generator, and a scalable coefficient input connected to the code input of the code-to-frequency converter are introduced, the output of which is connected to the first information input of the switch, the second information input of which is connected to the output of the third frequency generator, and its control input is inverse the trigger output, the information D-input of which is connected to the transfer output of the reverse counter, the subtracting input of which is combined with the control C-input of the trigger and the thermal output the educator, while the output of the first frequency generator is connected to the second input of the And element, and the output of the switch with the input of the frequency converter to the code.

 The above indicates the presence in the claimed technical solution of distinctive signs from the prototype, including both additional elements (switch, frequency generator), and new connections between them and the elements of the prototype. These elements are widely used in measurement technology. In the claimed technical solution, all elements of the device are used for their intended purpose, while exhibiting individually known properties. However, taken together, these elements and elements of the prototype, preserved and new relationships characterize a new property that is not inherent in either the prototype or any of the known analogues: expanding the functionality of the thermometer. This property does not repeat any of the known properties of distinctive features and is not their sum. In other words, each of the introduced elements, taken separately, is necessary to ensure the formulated positive effect, and all of them together, i.e. taking into account all the interconnections, they are sufficient to distinguish the device as a whole from others of a similar purpose and characterize it in that quality, which manifests itself in an ultimately total result, namely in expanding the functionality of the thermometer.

 Figure 2 shows the proposed device.

 The proposed device comprises a temperature converter 1 with a frequency output, first 2 and second 3 frequency generators, a reversible counter 4, element 5, trigger 6, an indication unit 7, a frequency to code converter 8, a code to frequency converter 9, the frequency input of which is connected to the output the second frequency generator 3, while the summing input of the reverse counter 4 is connected to the output of the And 5 element, the first input of which is connected to the output of the trigger 6, and the output of the frequency converter 8 to the code is connected to the input of the display unit 7. In addition, the thermometer contains a switch 10, a third frequency generator 11 and an input 12 of a scalable coefficient connected to the code input of the code to frequency converter 9, the output of which is connected to the first information input of the switch 10, the second information input of which is connected to the output of the third frequency generator 11, and its control input to the inverse output of trigger 6, the information D-input of which is connected to the transfer output of the reverse counter 4, the subtracting input of which is combined with the control C-input of trigger 6 and the output one of the thermocouple 1, while the output of the first frequency generator 2 is connected to the second input of the element And 5, and the output of the switch 10 with the input of the frequency converter 8 in the code.

где F(t) выходная частота термопреобразователя 1;
t температура;
а постоянный коэффициент.The digital thermometer is in continuous operation. It provides linearization of the characteristics of thermal converters with the dependence
F (t) = a

where F (t) is the output frequency of the thermal converter 1;
t temperature;
but a constant coefficient.

 The device operates as follows.

Suppose that at the initial moment of time, the reverse counter 4 and trigger 6 are in the zero state. A scale code N is applied to input 12. Frequency generators 2,3 and 11 generate pulse sequences with frequencies F ₁ , F ₂ and F _3, respectively, with F (t) <F ₁ ≥ 2 ^l F (t), F ₂ ≥ F (t) and F ₃ ≥ F (t), where l is the bit depth of the reverse counter 4.

 On the information input of the trigger 6 from the output of the reversible counter 4 is a signal of a unit level. Therefore, the first pulse of the thermal Converter 1 on the leading edge translates the trigger 6 into a single state.

The reversible counter 4 on the subtracting input is triggered on the trailing edge of the pulses of the input signal, and trigger 6 on the leading edge. Logical "1" from the direct output of trigger 6 opens the And 5 element. The pulses from the frequency generator 2, following with a frequency of F ₁ , begin to pass through the And 5 element to the summing input of the reversing counter 4. Since the state of the reversing counter 4 changes, then it the logical signal "0" appears at the output, which is input to the D-input of trigger 6. The leading edge of the next pulse coming from the thermal converter 1 to the control C-input of trigger 6 sets trigger 6 to zero. As a result of this, the passage of pulses through the element And 5 to the summing input of the reverse counter 4 is stopped.

Thus, a signal is generated at the direct output of trigger 6, which is equal to the period τ _{o of the} input pulses F (t) of the thermal converter 1. Therefore, m pulses of the reference frequency will arrive at the summing input of the reverse counter 3 during the time τ _o :
m F ₁ τ _o .

Since during the pulse counting, the summing input to the subtracting input of the counter 4 receives one trailing edge of the input frequency, the number recorded in the reverse counter 4 will be equal to
m _pc m-1.

Next, the pulses of the input signal from the output of the thermocouple 1 continue to be fed to the subtracting input of the reversible counter 4. After receipt of m-1 pulses, the reversible counter 4 returns to zero and a logical “1” appears at its output. The next pulse from the output of the thermocouple 1 again puts the trigger 6 in a single state at a time τ _o , and the process is similarly repeated.

 The device’s operation is based on the digital conversion method frequency, time interval, frequency, at the frequency setting of reference values and the organization of their two-channel frequency switching.

а на инверсном длительностью τ₁ T τ_o F₁τ_o ² τ_o.In the steady state, a pulse sequence of duration τ _o is formed at the direct output of trigger 6, and at its inverse output, τ ₁ = (m-1) τ _o with a repetition period
T τ _o + τ ₁ τ _o + (m 1) τ _o
τ _o + mτ _o τ _o mτ _o
F ₁ τ _o τ _o F ₁ τ _o ²
Thus, at the direct output of trigger 6, a sequence of time-pulse signals of duration τ _{o is formed} , which follows with a frequency
F (x)

and on the inverse duration τ ₁ T τ _o F ₁ τ _o ² τ _o .

 The code-to-frequency converter 9 linearly converts the code to a frequency, i.e. produces a pulse sequence with a frequency, the average value of which is proportional to the corresponding control code, and can be made in the form of a binary frequency multiplier with a dynamic frequency output.

где n разрядность преобразователя 9 кода в частоту.The frequency input of the code converter 9 into the frequency receives a pulse sequence from the frequency generator 3, the next with a frequency of F ₂ . Therefore, at its output, a pulse sequence with a frequency of
F _{d / f}

where n is the bit depth of the code-to-frequency converter 9.

где t текущее время;
Т период следования времяимпульсного сигнала на инверсном выходе триггера 6, равный F₁τ_o ²;
τ_o длительность времяимпульсного сигнала на прямом выходе триггера 6;
k 0,1,2,
n разрядность преобразователя 9 кода в частоту.This sequence of pulses is fed to the first information input of the switch 10, made in the form, for example, of the 2-OR element. The second information input of the switch 10 receives a pulse sequence with a frequency F ₃ from the output of the frequency generator 11, and its control input is time-pulse signals from the inverse output of the trigger 6, under the control of which the pulse sequences are transmitted to its information inputs, i.e., through switch 10 to the frequency input of the frequency Converter 8 in the code receives a pulse sequence with a frequency
F _MUX (t)

where t is the current time;
T is the repetition period of the time-pulse signal at the inverse output of trigger 6, equal to F ₁ τ _o ² ;
τ _{o the} duration of the time-pulse signal at the direct output of the trigger 6;
k 0,1,2
n the capacity of the Converter 9 code to frequency.

τ_oF(x)+F₃τ₁F(x)

+

+ F

1

+ F

1

+ F

F(t) +

(F₁-F(t)).During the time θ, which is much longer than the pulse repetition period from the thermal converter 1 and determined by the design of the converter 8, N _x pulses will arrive at the input of the converter 8:
N _x

τ _o F (x) + F ₃ τ ₁ F (x)

+

+ F

1

+ F

1

+ F

F (t) +

(F ₁ -F (t)).

 Thus, the device reproduces the functional dependence, due to which a wide range of frequency dependencies can be realized.

F²(t).As an example, to obtain a square dependence, it is enough to ask the following frequency ratio:
F ₂ F (t), F ₃ 0, in the particular case we get
N _x

F ² (t).

a выходной код N_х преобразователя 8 однозначно связан с измеряемой температурой N_х t. Этот код отражается цифровым индикатором блока 7 индикации.Consequently, with this ratio of frequencies, the code at the output of the converter 8 is proportional to the square of the frequency of the thermal converter 1, which corresponds to the functional characteristic of the prototype. When the condition is met

a output code N _{x of the} converter 8 is uniquely associated with the measured temperature N _x t. This code is reflected by the digital indicator of the indication unit 7.

a,

b,F₃θ= c, F(t) x, устройство воспроизводит функциональную зависимость полинома вида ах²-bx+c.An important advantage of the claimed device is its wider functionality. For example, while providing the value of F ₂ F (t), denoting

a,

b, F ₃ θ = c, F (t) x, the device reproduces the functional dependence of a polynomial of the form ax ² -bx + c.

Например, при обеспечении исходных соотношений частот F₂ 0, F₃ F₁ получаем зависимость вычитания двух частот
N_x θ [F₁-F(t)]
Например, при обеспечении исходных соотношений F₂

(F₁-F(t)) получаем зависимость суммирования двух частот
N_x

F(t) +

или
N_x

(F(t)+F₃)
При обеспечении исходных соотношений частот F₃ 0, F₁=F(t) получаем
N_x

Таким образом предлагаемое устройство по отношению к прототипу имеет более широкие функциональные возможности, что приводит и к расширению класса решаемых задач.For example, while ensuring the value of F ₃ 0, we obtain a multiplier-dividing dependence
N _x

For example, while providing the initial frequency ratios F ₂ 0, F ₃ F ₁ we obtain the dependence of the subtraction of two frequencies
N _x θ [F ₁ -F (t)]
For example, while providing initial ratios F ₂

(F ₁ -F (t)) we obtain the dependence of the summation of two frequencies
N _x

F (t) +

or
N _x

(F (t) + F ₃ )
Providing the initial frequency ratios F ₃ 0, F ₁ = F (t) we obtain
N _x

Thus, the proposed device in relation to the prototype has wider functionality, which leads to the expansion of the class of tasks.

 At the same time, the proposed device is much simpler than the prototype, as it allowed to abandon the use of a number of prototype blocks (one counter, two AND elements), and in addition to this, only a two-digit frequency switch was added.

 As a result of reducing equipment costs, the reliability of the device also increased, the numerical characteristics of which will depend on the method of technological implementation.

Claims (1)

 A DIGITAL THERMOMETER containing a temperature converter with a frequency output, first and second frequency generators, a reversible counter, an I element, a trigger, an indication unit, a frequency to code converter, a code to frequency converter with a frequency input connected to the output of the second frequency generator, and with a code input wherein the summing input of the reverse counter is connected to the output of the element And, the first input of which is connected to the output of the trigger, and the output of the frequency converter to the code is connected to the input of the display unit, characterized in that it introduced a switch, a third frequency generator, the code input of the code to frequency converter is made in the form of a scalable coefficient input, and its output is connected to the first information input of the switch, the second information input of which is connected to the output of the third frequency generator, and its control input to the inverse trigger output , the information D-input of which is connected to the transfer output of the reversible counter, the subtracting input of which is combined with the control C-input of the trigger and the output of the thermal converter, while Exit first oscillator frequency is coupled to the second input of AND and kommutatota output to the input of the frequency converter to the code.

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