JPS58214824A - Temperature measuring apparatus - Google Patents

Abstract

PURPOSE:To enable the indication of temperature linearized by reading out and displaying temperature data corresponding to a digital signal giving a thermistor output from an ROM IC. CONSTITUTION:The relationship between output voltage of a thermistor circuit and temperature data is determined by measurement or calculation and the temperature data is memorized into memorys IC 5 and 6 corresponding to the output voltage. Consequently, temperature data corresponding to the output voltage of a thermistor is obtained in a BCD code 3 digit from IC 5 and 6. The temperature data from data terminals 5D and 6D of the IC 5 and 6 is inputted into BCD-7 segment conversion sections 7-9 digit by digit to drive numerical displays 10-12 for displaying data for the first, second, and third digit data separately whereby the temperature data is displayed in digital number.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides (1) a frog measuring device that converts a temperature change into a resistance change, such as a thermistor, resistance temperature detector, or thermoelectric lamp, and measures the temperature by measuring this resistance value; It is related to.

Conventionally, temperature has been determined using a thermistor, resistance temperature detector, or thermocouple that converts temperature changes into resistance changes. However, since the resistance change of these elements is not linear with respect to temperature change, some sort of arranging function is required to increase measurement accuracy or to use them over a wide temperature range. For example, if we take a thermistor as an example of a device with the most extreme resistance change, the thermistor exhibits a temperature-resistance change as shown in FIG.

In FIG. 1, the horizontal axis shows the temperature T, and the vertical axis shows the resistance value R. One of these changing characteristics as shown in Figure 1
1, it is not possible to directly read the temperature from the resistance value, so do this;
In many cases, a circuit like the one shown in FIG. 2 is constructed for arranging. In the figure, / is a thermistor connected in parallel with a resistor λ, which is further connected in series with a resistor 3, and connected between the power source and ground of one circuit. Then, the voltage V between the ground and the terminal is taken out as an output.

This output voltage V shows a change as shown in FIG. 3 with respect to temperature. That is, if the horizontal axis is the temperature T and the vertical axis is the voltage (2), the output voltage decreases almost linearly as the temperature rises. If resistances C and 3 are appropriately selected, this graph can be made almost straight.

However, when widening the measurement temperature range or requiring highly accurate temperature measurement, characteristics closer to a straight line are required, and for these purposes a linearization circuit or device called a linearizer is required. It is. However, since such circuits and devices use a large number of precision resistors, variable resistors, or operational amplifiers, adjustment is complicated and expensive.

This invention was made in order to eliminate the drawbacks of such conventional devices and circuits, and the output voltage of the thermistor circuit is converted into a digital signal by an analog-to-digital conversion circuit, and this signal is written in advance in a memory such as a ROMIC. temperature data corresponding to the digital signal,
It is an object of the present invention to provide a temperature measuring device capable of displaying a magnified temperature by displaying it on a readout display, without requiring a special grinning device.

Further, according to the present invention, by providing a multiplexer, temperature signals from a large number of temperature detection circuits can be selectively measured and displayed.

Hereinafter, one embodiment of the present invention will be explained based on the block diagram of FIG. 4. In the figure, the thermistors 2a to
2f is a parallel resistance, and 3a to 3f are series resistances. M is a multiplexer which selects the thermistor circuit of the corresponding circuit by the selection signal S. DA is an analog-to-digital converter (hereinafter referred to as A/D converter), which inputs the output voltage of the thermistor circuit selected by the multiplexer M and converts it into a digital signal.

! and 6 are memory ICs that are configured with ROMICs that do not lose data even in the event of a power outage. This includes chip select signal terminals a and 6a and read signal terminals b and 6b.
etc., but this should be in the active state so that it can be read at all times. and.

The A/D converter q is connected to the address terminals jc and Ac.
Connect the output signal of , and access the memory directly. Memory IC! For example, if a cokilobyte is used for 6 and 6, the address signal will have a //bit configuration of AO to A/θ, so the output signal of the A/D converter DA may also have a //bit configuration. Of course, if the memory of the memory IJIC is not to use all λ kilobytes but only 1 kilobyte, the output signal of the A/D converter only needs to be IO bits. The data configuration of memory ICs and 6 is Po-Pt.
This is the t-bit configuration of . When this t bit is used as a BCD signal, the BCD signal can only be configured with a number of digits, so if two memo IJICs are used, a 3-digit or double-digit BCD can be configured. In this example, Memo+7 I
This shows a case where one of C and B is used and the BCD is configured with three digits.

As the memorized contents of the memo IJIC3 and B, temperature data corresponding to the digital output signal of the A/D converter DA is written in advance at an address corresponding to the output signal and is filled to an appropriate size.

That is, 1. For example, find the relationship between the output voltage of the thermistor circuit shown in the graph on the left and the temperature data by measurement or calculation, and store the temperature data in correspondence with the output voltage in the memories TC and 6. . In the left diagram, for example, point 20 on the graph is the point at 0° C., and the output voltage at this time is 20V. Further, point 2/ is a point at 30° C., and the output voltage at this time is /, lv. Similarly, the point here is set at -30°C, and the output voltage at this time is J, 2 V.

Although the graph is not based on direct current, a fixed curve can be obtained as long as the values of the series resistor 3 and the parallel resistor 2 are determined. Therefore, find the temperature value corresponding to each JmV increment or mVq increment of the output voltage, and first calculate the temperature value corresponding to the address in the memory corresponding to this output voltage by BCD.
, 7 digits, the above configuration allows temperature data corresponding to the output voltage of the thermistor to be obtained from the memory card C and 6 as a 3 digit BCD code. This temperature data is output from data terminals 5d and 6d of memory cell Cj,4. BCD this temperature data for each digit
- 7-segment conversion unit 71g: Numerical display 10 that inputs data into 9 and displays the 1st digit, 0th digit, and 3rd digit data, respectively.
//, drive /2.

The temperature data is displayed in digital numbers.

In addition, in the above embodiment, the output voltage is λmV or ! m
V has been shown in increments of K, but the capacity of the memory IC can be increased, and the scale of the fifth output voltage can be made smaller increments, such as /mV increments, and the corresponding temperature can be stored. For example, even higher precision can be obtained, and even higher precision can be obtained by using double digits as the counter button numeric display. Further, although the multiplexer M has six circuits a through in this embodiment, if a larger number of circuits is provided, a larger number of temperature sensors can be connected.

Further, the multiplexer selection signal S may be a signal from an external computer or may be a manual signal.

Further, in this embodiment, a thermistor has been described, but the present invention can also be applied to a case where a thermocouple or a temperature-measuring resistor is used as a temperature sensor. Also memo +7 IC! It is also possible to output the output of B to a display circuit, branch it out, input it to a computer, etc., and perform data processing. Furthermore, if it is incorporated into a device that uses an arithmetic processing device such as a microcomputer, there is an advantage that the memory of the microcomputer can be utilized. Furthermore, if a target salinity setting means and a temperature comparison means are added, the present invention can be used as a temperature controller or an alarm, and the scope of application of the present invention is extremely wide.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the temperature-resistance characteristics of a general thermistor, and FIG. 2 is a circuit diagram showing an example of a general linearization circuit for directing the characteristics of the thermistor. FIG. 3 is a diagram showing the temperature-resistance characteristics of the circuit of FIG. 2. FIG. q is a block diagram showing a temperature measuring device according to an embodiment of the present invention, and FIG. 5 is a diagram for explaining the operation of the QIA. In the figure, / is the thermistor, 2 is the parallel resistor, 3 is the series resistor, q is the A/D converter, ! and 6
is memo+7 IC, and RIa and 6a are chip select signal terminals of each IC. sb and 6b are read signal terminals of each IC. 3c and 6c are address signal terminals of each IC. jd and 6d are data signal terminals of each IC. ? , t and de are 1 digit, ko digit and 3 digit BC respectively
D-7 segment converter, 10. // and 12 are f'L1 digit, C digit and 3 digit number display 1M are multiplexers, and S is a multiplexer selection signal. Note that the same reference numerals in the figures indicate the same or corresponding parts. Agent Makoto Kuzuno - Written amendment to Homura 2 drawing procedure (voluntary) Commissioner of the Japan Patent Office 1, Indication of case Patent application No. 1983-, No. 17/σ-
21 Name of the invention Temperature measuring device 3, person making the amendment Subject of amendment (1) Column 4 for detailed explanation of the invention in the description Contents of the amendment The description will be corrected as follows.

Claims (3)

[Claims] (1) A plurality of temperature detection means for extracting signals corresponding to m degrees, a signal selection means for selecting signals from the plurality of temperature detection means, and a signal selected by the signal selection means as a digital signal. an A/D converter for converting the temperature data into a temperature data, a memory section for storing temperature data corresponding to the output of the A/D converter, and a memory section for reading out the temperature data corresponding to the temperature data from the memory section based on the output of the converter and storing the temperature data. 1. A temperature measuring device comprising: means for displaying numbers. (2) The hot water temperature measuring device according to claim 1, wherein each of the plurality of temperature detection means includes a thermistor, a parallel resistance, and a series resistance. (3) The temperature measuring device according to claim 1 or 1, wherein the storage section is constituted by a ROMIC.