JPS6015009B2 - temperature display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a temperature display device that switches the display when the measured temperature range is wide, such as when measuring and displaying the temperatures of the freezing compartment and the refrigerating compartment of a refrigerator-freezer or the like.

Conventionally, in temperature measurement, when measuring the temperatures at two or more different points, the temperature sensors are switched and inputted to the measurement circuit, and the same temperature range is displayed.

However, as the measurement temperature range of temperature sensors such as thermistors becomes larger, the linearity of the conversion between temperature and electricity deteriorates, making it extremely difficult to accurately display temperatures with large temperature differences within the same temperature range. It's coming. Also, the temperature range becomes wider. Therefore, in this invention, instead of switching the temperature sensor, the initial setting value of the counting circuit built in the temperature display circuit can be set according to the measurement temperature range, and two or more thermoelectric conversion circuits each having a temperature sensor, By making it possible to switch the range of the measured temperature display device at the same time, the purpose is to accurately display temperatures that have a large temperature difference, such as in the freezer compartment and the refrigerator compartment.

In this temperature display circuit, the temperature sensor and thermoelectric conversion circuit are adjusted so that the output frequency of each thermoelectric conversion circuit is the same when the measured temperature is the lowest value in the measured temperature range, and the temperature at that time is adjusted so that the output frequency of each thermoelectric conversion circuit is the same. Make the display the initial value of the counting circuit.

For example, in a refrigerator-freezer, the temperature of the freezer compartment is -25q0
When displaying in the range of -10℃ and the temperature of the refrigerator room -5℃ to -10qo, the measured temperature is -25℃ and -5℃, respectively, and the output frequency of each thermoelectric conversion circuit is 100KH.
Z, the counting circuit does not count, and the temperature display is the initial set value of -25°C and -5°C. According to the present invention, it is possible to use the temperature sensor's range of good linearity by simply switching the temperature display, and the display temperature range is also significantly reduced, allowing for highly accurate display.

A detailed explanation will be given below with reference to FIG. 1, which is an embodiment of the present invention.

Reference numerals la, lb, and 2 are oscillation circuits, and part of the resistance that determines the oscillation frequency is constituted by thermistor claws a, Thb, and fixed resistor R, respectively.

The output of an oscillation circuit 2 which oscillates at a constant oscillation frequency with a fixed resistor R is frequency-divided by a frequency divider circuit 3, and converted into predetermined timing signals T, , L, T3 by a timing circuit 4. Here, with the timing signal T, each frequency divider circuit 8 except frequency divider circuit 3.
10, the initial value of the temperature of the freezing or refrigerating compartment stored in the preset circuit 13, that is, the lowest value of the measured temperature, is read out and the value is set in the counting circuit 11.

FIG. 3 shows a specific example of the preset circuit 13 and the counting circuit 11. That is, a 7-stage flip-flop circuit 110
1, 1102, . . . 1107 are connected in series, and the output of the Q terminal of each circuit is supplied to the latch circuit 12. Further, the preset terminal P of each of the flip-flop circuits is
r has seven AND circuits 1301, 1302...1307
The contents of the counting circuit 11 are preset by the timing signal T, with the stored contents of the respective AND circuits. That is, according to the present invention, the first four stages store the displayed value of the first digit of the thermometer, the next two stages store the second digit, and the final stage stores the displayed value with a minus sign. .

Table 1 below shows the encoded minimum temperatures of the freezer compartment and refrigerator compartment. Table 1 As is clear from this figure, the first digit of the temperature in the freezer and refrigerator compartments was unified to 5, and was commonly encoded and stored as a BCD code.

Therefore, AND circuits 1301 and 13 that memorize the first digit
03 is supplied with an “H” level signal, and 1302/130
4 is regarded as the "L" level. Then, for the second digit, switch 6 is turned on and turned OFF, and when it is turned on, the AND circuit 130
Only 6 is preset as "H" level, encoded and stored to display the number 2, and when switch 6 is OFF, AND circuits 1305 and 1306 are both set to "L", and the digit of the preset counting circuit is stored. is encoded and stored so that it is not displayed, and the displayed temperature of the freezer compartment and refrigerator compartment is switched. Further, the AND circuit 1307 at the final stage displays the lowest temperature regardless of whether it is in the freezer compartment or the refrigerator compartment by encoding it to the "H" level and storing and presetting it. These AND circuits have one input terminal connected in common, and when the timing signal T is supplied from the input terminal a, the presetting of the initial value is completed. Next, when the presetting is completed, the thermistor Tha,mb whose resistance value changes depending on the ambient temperature is activated by the output b of the timing circuit 4 for the time period of the timing signal T2.
The selection circuit 5 selects one of the outputs of the oscillation circuits la and lb whose oscillation frequency is determined by the measured voltage of the switch 6 and supplies it to the gate circuit 7, and its output d is supplied to the frequency dividing circuit 8.

When the frequency dividing circuit 8 counts a predetermined number, the gate circuit 9 is activated by the output e of the frequency dividing circuit 8, and the output f of the gate circuit 7 is activated.
A frequency dividing circuit is supplied. Further, when the frequency dividing circuit 10 counts a predetermined number, the output g is supplied to the counting circuit 11, and the counting circuit 11 counts the output g.

Then, when the time of the timing signal T2 ends, the content of the counting circuit 11 is latched in the output latch circuit 12 by the timing signal T3, and an output of 0 to on is obtained. Although not shown, this is converted into a code and displayed digitally. The internal temperature is measured. The value of this preset circuit 13 is determined by the state of the switch 6. For example, according to FIG. 3, when the switch 6 is closed, it is set to 15, and when it is closed, it is set to -25, and at the same time, the oscillation circuit la and lb selection circuit 5 selects la when the switch 6 is open, and lb when it is closed. do. Then, the next measurement is performed according to the timing described above. During this time the display will show the previously measured temperature. In the case of a refrigerator-freezer, the service
Mr. Tha is installed in the refrigerator compartment, and the thermistor Thb is installed in the freezer compartment.

Here, a more detailed explanation will be given assuming that the refrigerator compartment, that is, the oscillation circuit la is selected, and the initial setting value is -5. The oscillation frequency of the oscillation circuit la is set, the frequency of the oscillation circuit 2 is set to 5, the count number of time pulses of the timing signal T2 by the frequency divider circuit 3 is set to M, the count number of the frequency divider circuit 8 is set to N, and the frequency divider circuit 10 If the count number of is K, the content A of the counting circuit 11 for each measurement is A=-5
}/K.

Here, if M=N, the display will be -5℃ when fa=f2
becomes.

In this way, the values of M, N, and K are determined by thermistor ma or mlb.
By appropriately setting the temperature according to the temperature change rate, it is possible to use any thermistor, which is extremely effective. As explained in detail above, according to the present invention, even when the measured temperature range is large, the measured temperature display width can be made small, and the temperature sensor can be used according to the measured temperature, so the linearity of the temperature sensor is improved and the temperature accuracy is improved. It is possible to provide a temperature display circuit with different measurement temperature ranges.

[Brief explanation of the drawing]

Figure 1 is a block diagram of one embodiment of the present invention, and Figure 2 is a time chart explaining the operation of Figure 1.
~g is a diagram representing the signals at points a to g shown in FIG. 1,
FIG. 3 is a circuit diagram showing a specific example of the main blocks of FIG. 1. In addition, la, lb... hot electric conversion circuit, 5...
...Selection circuit, 11...Counting circuit, 13...
...This is a preset circuit that sets appropriate values in advance. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. Two or more thermoelectric conversion circuits that have temperature sensors and convert temperature into frequency, a selection circuit that switches the output of the thermoelectric conversion circuits according to the measured temperature range, and a reference signal generator that generates a reference frequency signal. a frequency dividing circuit that divides the frequency of the pulse signal of the reference signal generation circuit, a timing circuit that generates a timing signal from the frequency-divided reference signal, and a gate circuit that receives the output of the selection circuit and the timing signal as input; A frequency dividing circuit and a gate circuit that input the output of this gate circuit, a counting circuit that inputs the output of this gate circuit through the frequency dividing circuit, a preset circuit that is set by this counting circuit, and latches the contents of the counting circuit. Temperature display device equipped with a circuit.