JPS5842914Y2 - temperature detection device - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a temperature detection device using a crystal sensor.

The number of air conditioning equipment and other important equipment for temperature control is increasing, and in order to perform remote temperature measurement, temperature information detected by temperature sensors, etc. is converted into a frequency change signal, and that signal is transmitted over a transmission line. For example, there is a device on the market that compares the frequency with a reference frequency in a temperature detection device provided in a central monitoring unit and detects the temperature from the difference in frequency.

This method has the advantage that not only does the length of the transmission line (cable) and temperature changes in the location where the transmission line is wired not affect the measurement results at all, but it also allows remote measurement over 100 meters. There is.

The present invention relates to an improvement of the signal processing section in a temperature detection device other than a thermometer sensor using this method, and will be described in detail below.

First of all, since crystal sensors are well known, I will give only an overview.A crystal oscillation circuit (oscillation frequency is, for example, The slope of the frequency versus temperature characteristic (28MHz) is 1000Hz/'C, and a thermometer using such a crystal sensor is said to have a resolution of 0.0001C.

The crystal piece is attached to the tip of the sensor probe, and together with a sensor oscillation circuit using the crystal piece as a resonator, the crystal piece is housed in a stainless steel probe, making up a sensor as a whole.

Since the oscillation frequency of the sensor oscillation circuit changes linearly depending on the temperature of the object to be measured, a part of the output of the oscillator is guided to the thermometer body, that is, the temperature detection device, by a cable.

Figure 1 is a block diagram of a configuration example of a conventional temperature detection device;
The figure is a block diagram of an example of a configuration in which the present invention is implemented, and the same symbols represent circuit parts having the same function.

First, in Figure 1, 1 is the input from the sensor oscillation circuit, 2
is a reference temperature frequency input, 3 is a mixer part (frequency difference pulse conversion circuit), and 4 is a reference oscillator (for example, 28.208 MHz l/i with respect to 0°C.

(This is a 2.8208MH7 oscillator that requires remarkable stability and is generally housed in a constant temperature bath), 5 is a 10x frequency multiplication circuit (hereinafter referred to as frequency doubling circuit), 6 is a frequency division circuit, 1 is a gate control circuit, 8 is a counter section, for example, a 6-digit counter and its display, and 9 is a positive/negative temperature indicator, ie +
or - indicator, 10 is a digital signal output.

The output 1 of the sensor oscillator for the measured temperature is the reference oscillator 4
The mixer 3 compares the frequency output 2 with the frequency output 2 which is 10 times higher than the frequency output 2 and detects a difference frequency, which is converted into a pulse and sent to the counter section 8.

+ depending on which one is higher by comparing the frequencies of inputs 1 and 2.

Set the indicator 9 to + or -.

In addition, the output pulse to the counter section 8 is, for example, if the input 2 on the reference oscillator side corresponding to 0°C is 28MHz, the difference from the human power 1 on the sensor side is 1100OH'C and 20kHz at 20°C, so the pulse is 20kHz. becomes.

The counter section 8 measures the reference time (for example, 0.1, 1.1
The pulses sent within 0 sec) are counted, and the result is digitally displayed on a display using a light emitting diode, for example.

This reference time, that is, the gate time, is inputted from the reference oscillator 4 and divided by the frequency corresponding to the reference time in the frequency dividing circuit 6, and converted into a gate pulse in the gate control circuit γ. It is something.

In this way, if the temperature difference from 0° C. is directly counted by the frequency and the unit is set to 0° C., the temperature can be directly displayed, but the gate time setting is linked to the decimal point on the display.

That is, the gate time is 0. When I See, the resolution is 0.
．． The temperature reached 01°C for 1 sec.

0.001℃ and 0.0 at 10sec respectively
It becomes 001℃.

Note that the output 10 is used as an input to a temperature recorder, etc.

Now, the conventional device as mentioned above detects 0℃ using mixer 3.
Internally, this is done by comparing the magnitude of the frequencies of human power 1 and 2, so if you try to increase the detection accuracy, the circuit becomes complicated, and if you simplify the circuit, the detection accuracy at 0°C will decrease. , measurement range (e.g. -80 to +250
It was difficult to make the resolution the same over the whole range (°C).

The present invention was developed in view of these drawbacks, and will be explained in detail below with reference to FIGS. 2 to 4.

In FIG. 2, 11 is a part of a mixer, but unlike mixer 3 in FIG. 1, it is a circuit that only outputs pulses according to the frequency difference between two inputs 1 and 2.

Reference numeral 12 denotes a counter section, an example of its configuration is shown in FIG.

13 is a frequency divider, 14 is a gate control circuit, 15 is a temperature display, and 13 and 14 are the conventional circuits 6.
It can be considered to be the same as γ, but the input to 14 is the reference oscillator 4.
Alternatively, it may be obtained from an independent oscillator.

The structure of the counter section 12 is the focus of the present invention, and in FIG. 3 showing its structure contents, 16 is an addition/subtraction circuit, that is, a reversible (up/down) counter, and 1γ is an addition/subtraction switching signal generation circuit, that is, U p /D own ('U'
Aυ switching circuit, 18 is a 0°C detection circuit, 11a is the temperature signal (pulse) input from the mixer 11, 14a is the gate signal input from the gate circuit, and the temperature signal is controlled by the gate signal on the input side of the reversible counter 16. The circuit shall be included.

FIG. 4 is a time chart illustrating the operation of the counter section, and the operation of the circuit of FIG. 3 will be explained using this time chart.

(1) in FIG. 4 is a gate signal 14a supplied from the game circuit 14, and for example, a gate time τ of 1 second is used.

(2) is a temperature signal (frequency pulse) count signal (1)
It is passed only during the H level (or -, p) of , and becomes the counter input pulse of these reversible counters.

(3) is a zero detection signal, which is a pulse generated from the 0° C. detection circuit 18 when the outputs of each stage of the reversible counter all show the sign of O, as will be described later.

(4) is a pulse generated using the rising edge of the gate signal (1), and is generated in the U/I switching circuit 17.

The U/D switching circuit 17 starts the subtraction operation (giving the reversible counter a switching signal for negative level subtraction) with the signal (4), and resets it with the signal (3).

(5) is the above same Φ switching signal which is the output of the circuit IT,
The signal is input to the Φ signal input terminal of the counter circuit 16.

The above operation will be explained next using actual numerical values.

The measuring range of this temperature measuring device is, for example, -50°C to 10°C.
If the temperature is 0°C, a number corresponding to -50°C is preset in the reversible counter.

The temperature gradient of the sensor was set to 100. OHz/°C
The oscillation frequency of reference oscillator 4 is 2.8105MHz.
Assuming that 105MHz matches the oscillation frequency of the sensor oscillator at -50°C, the difference between the sensor oscillator frequency and the reference frequency at -50°C is 0kHz,
If this is pulsed, it becomes 0 pulses/second.

In other words, -50℃ is the preset value of the counter 50.00
Displayed as 0.

Note that when the gate time is 1 second, the resolution is 1/1000° C. as described above, so the decimal point is after 50 and up to three digits below the decimal point are displayed.

Now, if the temperature measured by the sensor is +20°C, the difference between the sensor oscillator frequency and the reference frequency is 70 kHz, and if you count this with a counter, it should be 70,000 pulses/second, but this is the third In the apparatus according to the present invention shown in FIGS.

First, 70 input to the counter by gate signal (1)
Since the counter is in a subtraction state at this time, the kHz pulse is subtracted from the preset value of 50 ffi O and finally corresponds to 0°C.

o, oo. reach.

The 0°C detection circuit 18 monitors each bit of the counter separately, and when all the bits indicate O, it outputs it to the 0°C detection signal history Φ switching circuit 11 and switches the counter to addition, so that the subsequent count 20. 000 indicates 20.000°C.

As described above, the accuracy of the O.degree. C. detection signal is important, but it is certain because all bits of the counter are monitored.

The required number of bits for both the naori counter and the display differs depending on the required resolution, and the gate time τ is changed, but in order to keep the resolution the same within the measurement range, monitor up to the bit one digit smaller than the resolution of the detection device. I have decided to do so.

For example, even if the number of effective digits is 3 digits and the resolution ability is 1/10'C, the monitoring bits are 4 digits, and when all 4 bits are O, 0°C is detected.

In addition, the (to) display 90 input in FIG. 2 is the output 5 of the circuit 1γ.
Alternatively, the 0°C detection pulse (3) may be used.

If these are carried out using the device shown in Figure 1, the temperature 0°C can be detected by the fact that the frequency difference between the two manual inputs to the mixer 3 is equal to 50 kHz, and the positive/negative switching of the displayed temperature requires whether the temperature is greater or less than 50 kHz. It is clear that detection is required, and the circuitry is complicated and its accuracy is low, but since this device monitors all bits and detects 0°C, the detection accuracy is higher than conventional devices. , the resolution is also the same within the measurement range.

As explained above, the device of the present invention can generate the addition/subtraction switching signal of the reversible counter with high precision, so it is easy to measure and display the temperature continuously over the entire measurement range, and the sensor temperature at 0°C can be easily displayed. The advantages include that frequency variations can be easily absorbed by the counter section, for example, by correcting the preset value, and that the circuit configuration of the temperature detection device is simpler than conventional devices, and high accuracy can be obtained.
Since long-distance remote temperature control is possible, significant effects can be obtained when used in air conditioning equipment in places where temperature control is strict.

[Brief explanation of drawings]

Figure 1 is a block diagram of a configuration example of a conventional temperature detection device;
The figure is a block diagram of a configuration example of a temperature detection device embodying the present invention, FIG. 3 is a color measurement configuration of the counter section in FIG. 2, and FIG. 4 is a time chart L showing the operation of the counter section. 1... Input from sensor, 3... Part of mixer, 4... Reference oscillator, 5... Frequency doubler, 6... Frequency divider, 7... Kate control circuit, 8... Counter section, 9...
...ω indicator, 10...digital signal output,
11...Bexer part, 12...Counter part, 13...Divider, 14...Gate control circuit, 15...Temperature display Vessel, 16・
...Reversible counter, 1T...up/down switching circuit, 18...0°C detection circuit.

Claims (1)

[Scope of utility model registration request] An input that converts the temperature information of the object to be measured detected by a sensor into a frequency change signal, and an input from a reference oscillator or its frequency multiplier that generates a frequency corresponding to the lowest temperature in the measurement range or an integer fraction thereof. A temperature detection device that measures the high and low frequencies and the difference in frequency and digitally displays the temperature of the object to be measured and whether it is positive or negative is connected to the reference oscillator and frequency multiplier, the input from the sensor, and the reference. A mixer part that outputs a panel with a frequency equal to the difference between the inputs from the oscillator or frequency multiplier, a gate pulse generation circuit that generates a gate pulse that repeats the output of the mixer part and allows it to pass for a certain period of time, and the gate pulse a gate circuit that is opened and closed by a counter section, that is, a reversible counter that uses the rising edge of the gate pulse to subtract the pulse that has passed through the gate from a preset value that corresponds to the lowest temperature in the measurement range; a counter section comprising a 0°C detector that generates a 0°C detection pulse when all bits of the 0°C detection pulse become zero; and an up/down switching pulse generation circuit that converts the count of the reversible counter into addition from the 0°C detection pulse; Rise of the above gate pulse and 0°C
A temperature detection device comprising: a positive/negative temperature indicator whose display is inverted by a detection pulse; and a temperature indicator which displays the number of each bit of a reversible counter.