JPH0619294B2 - Temperature measuring instrument - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a thermometer and a temperature measuring device for observing and maintaining a device, and in particular, has a function of confirming a previous temperature measurement result during a temperature measurement operation. And an electronic temperature measuring device.

[Conventional technology]

This kind of electronic measuring instrument has been adopted in many fields in recent years, and in particular, it is rapidly becoming popular for household use in place of the conventional mercury thermometer because of its inconvenience.

However, since it does not have a function such as a mercury thermometer that can confirm the previous temperature measurement result prior to the temperature measurement operation, it is necessary to make a note of the previous temperature measurement value for each temperature measurement. It was complicated.

In order to solve such a problem, an electronic temperature measuring device has been proposed which has a memory function and holds the temperature measurement result even after the power is turned off so that the temperature measurement result can be read and displayed as needed. : Electronics Digest, Inc., Dec. 10, 1975, "CMOS IC Handbook," pages 287 to 293).

[Problems to be solved by the invention]

In the above-mentioned conventional example, a dedicated memory switch for reading the temperature measurement result from the memory unit is provided in addition to the switch for starting temperature measurement, which complicates the circuit configuration and the entire device. Since the size of the switch is increased and the two switches have to be operated separately, the operation is complicated and erroneous, and is not suitable for home use mainly by women and girls.

[Means for solving problems]

The present invention has been made in view of the above circumstances,
With the operation of the switch, the temperature measuring section is started to operate, and at the same time, the previous measurement value of the previous measurement held in the first storage section is written in the second storage section, and the first storage section is written. To hold the current temperature measurement value obtained from the temperature measurement unit and display the temperature measurement value according to the temperature measurement value, and according to the length of the operation duration of the switch after the operation of the temperature measurement unit, The display can be switched to display according to the previous temperature measurement value and the temperature measurement can be stopped, the circuit configuration can be simplified and the entire machine can be downsized, and the operation can be simplified and easy to handle. It was done.

〔Example〕

Hereinafter, embodiments of the present invention and drawings will be described. FIG. 1 is a block diagram showing an embodiment of a temperature measuring device according to the present invention, in which 1 is a switch, 2 is an oscillator, 3 and 4 are counters, 5 and 6 are RS type latch circuits, and 7 and 8 are counter,
9 is a control unit, 10 is a temperature measuring unit, 11 and 12 are storage units, 13
Is a multiplexer, 14 is a display decoder, 15 is a display, 16 is an RS type latch circuit, 17 and 18 are falling edge detectors, 19 to 22 are NAND gates, and 23 to 29 are inverters.

In the figure, the oscillator 2, the counters 3, 4, 7, and 8, the latch circuits 5, 6, and 16, the control unit 9, the temperature measuring unit 10, the display decoder 14, and the falling edge detection units 17 and 18 are reset respectively. When the signal supplied to the terminal R is at a high level (hereinafter referred to as "H"), it is in the reset state.

The switch 1 is a normally-open switch that can be operated from the outside, such as a push-button switch, a slide switch, or a switch that operates a lead switch provided in a case (not shown) from the outside by a magnet or the like. Is. When the switch 1 is not operated (that is, not closed), the counter 4 and the latch circuit 6 are reset with their reset inputs being "H", and one of the NAND gates 19 is reset. The input is "H".

The oscillator 2 is a CR oscillator, a crystal oscillator, or the like, and generates the reference clock MCK. This reference clock MCK is divided into a predetermined frequency by the counter 3, and the counters 4, 8
And to the display decoder 14. The oscillator 2 and the counter 3 output the output of the NAND gate 19 to the inverter 23.
It is switched to the operating or non-operating state by the MCK • ON signal obtained by reversing with.

It constitutes a judgment unit for judging that the counter 4, the latch circuit 5, and the switch 1 have been operated. In this determination unit, the counter 4 counts the clock from the counter 3 when the switch 1 is operated and the reset is released. When the counter 4 counts the first n,
The Qn output is inverted from a low level (hereinafter referred to as “L”) to “H”, and thereafter, every time the counter 4 counts n, the Qn output is inverted. Further, when the counter 4 continues to count and its Qn output is inverted k times, its Q
The output is inverted from "L" to "H". That is, the counter 4 further divides the clock from the counter 3,
The frequency division ratio for the Q output is set to k times the frequency division ratio for the Qn output. In the following description, k = 16.

On the other hand, the latch circuit 5 is set at the rising edge of the Qn output of the counter 4 after the reset is released, and its output is inverted from "H" to "L".

The counter 4 and the latch circuit 5 are in the reset state when the switch 1 is open, and the reset is released when the switch 1 is closed, so that the latch circuit 5 is operated every time the switch 1 is operated to be in the closed state. The output is inverted from "H" to "L". Therefore, this output indicates that the switch 1 has been operated by inverting it from "H" to "L".

The latch circuit 6 is in the reset state when the output of the latch circuit 5 is H, in the reset release state when the output is "L", and outputs the Q output of the counter 4 and the GRST1 signal from the inverter 24 described later after the reset is released. It is set at the rising edge of the signal obtained by processing in NAND gate 22 and inverter 26. Latch circuit 6
When the switch 1 is set, its Q output is inverted from L to H, but even if the switch 1 is operated, if the operation duration is shorter than the 16n counting period of the counter 4,
The counter 4 is reset before its Q output is inverted from "L" to "H", so the counter 6 is not set. On the other hand, when the operation duration of the switch 1 is longer than the 16n counting period of the counter 4, the latch circuit 6 is set. Therefore, the latch circuit 6 has a function as a determination circuit for determining whether the operation duration of the switch 1 after releasing the reset is longer or shorter than the counting period of 16n of the counter 4. The Q output of the latch circuit 6 is used as the SA signal by the multiplexer 13
It is used for switching control.

The counter 7 is a bit binary counter and counts one at the falling edge of the Q output of the latch circuit 5, and the Q output is inverted each time it counts. Q of counter 7
The output is inverted by the inverter 24 and supplied to the NAND gates 19, 21 and 22 as the GRST1 signal. The counter 7 is provided with a temperature measuring unit 10 as will be apparent from the description below.
It forms a selection unit for selecting whether to continue or stop the operation of.

The output of the latch circuit 5 is also supplied to the NAND gate 21, and the output of the NAND gate 21 is supplied to the inverter 2.
It is inverted at 5 to form the GRST2 signal. This GR
The ST2 signal is supplied to the reset terminal R of each of the counter 8, the control unit 9, the temperature measuring unit 10, the display decoder 14, the latch circuit 16 and the falling edge detection unit 17, and is inverted by the NAND gate 27 to be inverted by the NAND gate 20. Will also be supplied.

The counter 8 further divides the clock from the counter 3. The Ql output having the predetermined frequency division ratio is supplied to the control unit 9,
The temperature measurement by the temperature measuring unit 10, that is, the timing of temperature measurement is controlled. The Qm output having a frequency division ratio twice that of the Ql output is supplied to the latch circuit 16 as a set input. Latch circuit 1
After the reset is released, 6 is set at the first rising edge of the Qm output of the counter 8 and its output is inverted from "H" to "L". The trailing edge of this output is detected by the trailing edge detection unit 17, and a MAX.R signal representing the trailing edge is formed. This MAX.R signal resets the storage unit 11 composed of the D-type flip-flop, and erases the previously measured temperature value held so far.
The output of the latch circuit 16 is also supplied to the NAND gate 20.

The temperature measuring unit 10 operates when the reset is released, and measures the temperature once for each cycle of the Ql output of the counter 8. Each temperature measurement is completed immediately before the rising edge of the Ql output of the counter 8. Then, in synchronization with the rising edge of the Ql output, the temperature measurement value obtained at that time (hereinafter referred to as the current temperature measurement value) is compared with the temperature measurement value stored in the storage unit 11,
When the current temperature measurement value is large, MAX.phi. Is generated, and the current temperature measurement value is written in place of the temperature measurement value held so far. Therefore, the storage unit 11 retains the maximum temperature measurement value obtained so far after the temperature measurement unit 10 is reset.

In the storage unit 12, the temperature measurement value held in the storage unit 11 is written by the MEMO · φ signal of “L” obtained by inverting the Q output of the falling edge detection unit 18 by the inverter 29. The reset terminal R of the falling edge detector 18 is supplied with the MCK.ON signal obtained by inverting the output of the NAND gate 19 by the tomverter 23. After the resetting is released, the falling edge detection unit 18 detects the falling edge of the GRST2 signal from the inverter 25, and the inverter 29 outputs the "L" MEMO.
Generate φ signal.

The multiplexer 13 is controlled by the SA signal from the latch circuit 6, selects the temperature measurement value from one of the storage units 11 and 12 and sends it to the display decoder 14.

Although not shown, the multiplexer 13 is provided with a measurement range outside detection means, and when the selected temperature measurement value is outside the predetermined measurement range, the temperature is measured by the display unit 15 to display that fact. Data representing fixed numerical values, symbols, patterns, etc., instead of the values, is supplied to the display decoder 14.

Therefore, the predetermined measurement range is 32.0 ° C to 42.0 ° C.
And When displaying the previous temperature measurement value from the storage unit 12 selected by the multiplexer 13, this is 32.0.
When the temperature is below ℃,
“32.0 ° C.” is displayed, and when it exceeds 42.0 ° C., “42.0 ° C.” is displayed. When displaying the current temperature measurement value from the storage unit 11 selected by the multiplexer 13, when it is lower than 32.0 ° C.,
When “LO ° C” is displayed and the temperature exceeds 42.0 ° C,
“HI ° C” is displayed. As described above, in order to make the display contents of the previous temperature measurement value and the current temperature measurement value outside the predetermined measurement range different, the above-mentioned measurement range detection means is also controlled by the SA signal.

The display decoder 14 and the display 15 constitute a display section. The display decoder 14 does not send any signal to the display unit 15 at the time of resetting, so that the display unit 15 displays a blank display (that is, nothing is displayed). GRST
When the 2 signals become L and the display decoder 14 is reset, the output of the multiplexer 13 is decoded as long as the DisPR signal obtained by inverting the output of the NAND gate 20 by the inverter 28 is "L", The above display is performed at 15, but when the DisPR signal becomes "H", the display decoder 14 is preset and the reception of the output of the multiplexer 13 is prohibited, and the display 11 is provided with a signal for lighting all the segments. Supply.

Next, the operation of this embodiment will be described with reference to the timing charts of FIGS. 2 (a) and 2 (b).

First, regarding FIG. 2A, the previous temperature measurement value Nx ′ is held in the storage unit 12 even in the non-use state. When the power supply (not shown) is turned on, the display 11 is in operation and the counter 7 is reset, but the Q output of the counter 7 is "L" and the GRST1 signal is "H". Is. At this time, the switch 1 is in the open state,
Since the counter 4 and the latch circuit 5 are also in the reset state and the output of the latch circuit 5 is "H", the inverter 25
The GRST2 signal obtained from the above is also "H". For this reason, the display decoder 14 is in the reset state and the display 1
1 is displayed blank. In addition, the counter 8, the control unit 9,
Temperature measuring unit 10, latch circuit 16, falling edge detection unit 17
Is also in reset state. Further, since the latch circuit 6 is reset by the "H" output of the latch circuit 5, the SA signal which is the Q output of the latch circuit 6 is "L". The temperature measurement value from (in this case, the previous temperature measurement value Nx ') is selected. Furthermore, since one input on the switch 1 side of the NAND gate 19 is "H" and the other input which is the GRST1 signal is also "H", the MCK.ON signal is "H",
Therefore, the oscillator 2, the counter 3, and the falling edge detection section 18 are also in the reset state. Furthermore, GRS
The T2 signal is "H" and the Q output of the latch circuit 16 is "H". Therefore, the DisPR signal is "L".

In this state, when the switch 1 is closed, the reset between the counter 4 and the latch circuit 5 is released, and the input "H" to "L" at the switch 1 side of the NAND gate 19 is "inverted". It becomes "L", and the oscillator 2, the counter 3, and the falling edge detector 18 are reset. Therefore, the oscillator 2 generates the reference clock MCK, which is divided by the counter 3.

The counter 4 counts the clock from the counter 3, but when the count is n, the Qn output is inverted from "L" to "H", and the latch circuit 5 is set at the rising edge of the Qn output. Therefore, the output of the latch circuit 5 is inverted from "H" to "L", the latch circuit 6 is reset, and at the falling edge of the output, the counter 7 counts by 1 and its Q output is "1". The GRST1 signal is inverted from “L” to “H”, and the GRST1 signal is changed from “H” to “L”.
Flip to.

The output of the latch circuit 5 and this "L" of the GRST1 signal
GRST from the inverter 25
The 2 signal becomes "L", and the counter 8, the control unit 9, the temperature measuring unit 10, the display decode 14, the latch circuit 16 and the falling edge detection unit 17 are released from the reset state and brought into the operating state. Further, the trailing edge of the GRST2 signal is detected by the trailing edge detection unit 18, and the “L” MEMO · φ signal representing this trailing edge is supplied to the storage unit 12.
As a result, the previous temperature measurement value N stored in the storage unit 11
x ′ is written in the storage unit 12.

On the other hand, the output of the latch circuit 16 is kept at "H" and GR
Since the ST2 signal becomes "L", the DisPR signal becomes "H", the display decoder 14 is preset, and all the segments of the display 15 are turned on. At this time, the latch circuit 6 has been released from reset, but since it has not been reset, its Q output, and therefore the SA signal is "L".
And. The multiplexer 13 selects the temperature measurement value from the storage unit 11 (in this case, the previous temperature measurement value Nx '). However, since the display decoder 14 is preset, it does not accept the output of the multiplexer 13.

The switch 1 is continuously closed and the counter 4 is set to n.
Although the Qn output is inverted each time it is counted, the latch circuit 5 is kept in the set state as it is, and therefore the SA signal from the latch circuit 6 is kept at "L" and the GRST2 signal is kept at "L".

Now, before the counter 4 counts 16n, the switch 1
Is opened (operation is completed), the counter 4 and the latch circuit 5 are reset, and the output of the latch circuit 5 is inverted from "L" to "H". However, since this does not affect the counter 7 at all, the GRST1 signal is held at "L" as it is, and GRST2 is also held at "L". Further, the latch circuit 6 is reset before being set, its Q output is held at "L", and the multiplexer 13 is stored in the storage unit 1.
The temperature measurement value Nx 'from 1 is selected as it is.

On the other hand, the counter 8 counts the clock from the counter 3. Then, when the predetermined number 1 is counted, the Ql output is inverted from "L" to "H", and the rising edge of the Ql output is detected by the control unit 9, but the control unit 9 controls the temperature measurement unit 1
Do not signal 0. Further, when the counter 8 continues counting and the count value becomes 2l, the Ql output is inverted from "H" to "L", and the Qm output is inverted from "L" to "H". At the rising edge of this Qm output, the latch circuit 16 is set, and its output is inverted from "H" to "L".
The falling edge of this output is detected by the falling edge detection unit 17 to form the MAX.R signal, whereby the storage unit 11 is reset. As a result, in the storage unit 11, the previous temperature measurement value Nx 'is erased and the value 0 is held.

Further, since the latch circuit 16 is set and its output is inverted from "H" to "L", the inverter 2
The DisPR signal from 8 is inverted from "H" to "L",
The display decoder 14 is released from presetting.

Therefore, the display decoder 14 decodes the output of the multiplexer 13, but in this case, the multiplexer 13 selects the temperature measurement value from the storage unit 11, and this temperature measurement value is 0.
Therefore, the display unit 15 displays “L0 ° C.” by the out-of-measurement range detecting means in the multiplexer 13.

This state continues until the switch 1 is operated again.
Meanwhile, the counter 8 continues the counting operation, and when the count value becomes 3 l, its Ql output is inverted from “L” to “H”, and the control unit 9 detects this inversion and sends a signal to the temperature measuring unit 10. To send.

On the other hand, the temperature measuring unit 10 has completed the first temperature measurement immediately before the rising edge of the Ql output of the counter 8, and when receiving a signal from the control unit 9, the temperature measurement value is read from the storage unit 11. Current temperature measurement value N ₁ obtained by the _first temperature measurement
Compare with. In this case, since the read temperature measurement value is 0 and the current temperature measurement value N ₁ is larger, the temperature measurement unit 10 outputs M
The AX / φ signal is sent to the storage unit 11, and the current temperature value N ₁ is written in the storage unit 11. As a result, the display unit 15 displays the numerical value "T ₁ ° C" corresponding to the current temperature measurement value N ₁ .

Further, the counter 8 continues to count, and the count value becomes 4
At 1, the Qn output is inverted from "H" to "L", and when the count value is 5l, the Qn output is inverted from "L" to "H", but at the rising edge of this Qn output, the temperature measuring unit 10 The current temperature measurement value N ₂ obtained immediately before that is compared with the temperature measurement value N ₁ stored in the storage unit 11, and when the current temperature measurement value N ₂ is larger, the current temperature measurement value N ₂ is stored in the storage unit 11. Rewrite to the value N ₂ . Therefore, the display unit 15 displays the numerical value "T ₂ ° C" corresponding to the current temperature measurement value N ₂ .

In this way, the counter 8 keeps counting, and at the rising edge of the Ql output every 2l counts, the temperature measurement unit 10 compares the current temperature measurement value with the temperature measurement value held in the storage unit 11, and When the measured temperature value is larger, the storage unit 11 rewrites the measured temperature value. Therefore, in the storage unit 11,
After the reset, the maximum value among the temperature measurement values obtained so far is held, and during the period in which the temperature is rising, the temperature measurement value held in the storage unit 11 is updated for each temperature measurement, The numerical value displayed on the display unit 15 is updated each time.

After that, when the switch 1 is operated to be in the closed state, the reset of the counter 4 and the latch circuit 5 is released, and the output of the latch circuit 5 is inverted from "H" to "L" as described above. 6 is reset. At the same time, the counter 7 counts by 1, its Q output is inverted from "H" to "L", and the GRST1 signal is inverted from "L" to "H". However, since the output of the latch circuit 5 is "L", the GRST2 signal is held at "L" as it is. Also, the switch 1 of the NAND gate 19
Since the input on the side is "L", the MCK.N signal is also held at "L" as it is.

The closed state of the switch 1 continues, and finally the counter 4 becomes 1
When counting 6n, the Q output is inverted from "L" to "H". Therefore, since the GRST1 signal is "H", the output G4 of the NAND gate 2 changes from "H" to "L".
The output of the inverter 26 is inverted from "L" to "H", and the latch circuit 6 is set by this inversion. For this reason, the Q output of the latch circuit 6 is inverted from "L" to "H", the SA signal becomes "H", and the multiplexer 13 is turned on.
Selects the previous temperature measurement value Nx 'from the storage unit 12. The display decoder 14 decodes this, and the display unit 15 displays a numerical value "Tx '° C" corresponding to the previous temperature measurement value Nx'. When the previous temperature measurement value Nx 'is out of the predetermined measurement range, the measurement range detection means in the multiplexer 13 indicates "32.0 ° C" or "4" on the display 15.
Needless to say, it is displayed as "2.0 ° C".

On the other hand, the counter 7 is preset at the rising edge of the Q output of the latch circuit 6, its Q output is inverted from "L" to "H", and the GRST1 signal is inverted from "H" to "L". Therefore, the output G4 of the NAND gate 22 is "H".
Becomes

While the switch 1 is in the closed state, the display 15 displays “Tx ′ ° C.” corresponding to the previous temperature measurement value Nx ′, the temperature measurement unit 10 performs the temperature measurement operation, and the storage unit 11 displays A larger current measured value is written.

Therefore, when the switch 1 is opened and the operation is completed, the counter 4 and the latch circuit 5 are reset, the output of the latch circuit 5 is inverted from "L" to "H", and the latch circuit 6 is reset. Therefore, the SA signal changes from "H" to "L".
Then, the multiplexer 13 selects the temperature measurement value Nn ₊₂ from the storage unit 11, and the numerical value “Tn _{+ 2} ° C.” corresponding thereto is displayed on the display unit 15. Further, since the GRST1 signal is held at "L", the GRST2 signal is also held at "L", and the temperature measuring unit 10 continues to operate and the temperature rises. The content is updated and the display content of the display unit 15 is also updated.

Since this state is the same as the state before the switch 1 is closed for a period of 16n counts or more of the counter 4, the switch 1 is closed again by the display 15 by closing the switch 1 for 16n counts or more of the counter 4. Previous temperature measurement value N
Display according to x'can be performed.

In order to stop the operation of the temperature measuring device, the switch 1 may be closed for a period shorter than the 16n counting period of the counter 14.

This is shown in FIG. 2 (b), which shows a continuous state from FIG. 2 (a).
Will be explained.

When the switch 1 is closed, the counter 4 and the latch circuit 5 are reset, and the output of the latch circuit 5 changes from "H" to "L". At the falling edge of this output, the counter 7 counts by 1, and with this, G
The RST1 signal is inverted from "L" to "H". But,
Since the output of the latch circuit 5 is "L", GRST2
The signal is held at "L" and the temperature measuring operation is being performed. Further, the latch circuit 6 is released from reset, but is not set, so that the Q output remains "L".
A numerical value “Tx ° C.” corresponding to the temperature measurement value Nx from the storage unit 11 is displayed on the display unit 15.

Before the Q output of the counter 4 becomes “H” (that is, 1
If you close switch 1 (before counting 6n),
The counter 4 and the latch circuit 5 are reset, and the output of the latch circuit 5 is inverted from "L" to "H". For this reason, the GRST2 signal is also inverted from "L" to "H", and the counter 8, the control unit 9, the temperature measuring unit 10, the display decoder 14, the latch circuit 16 and the falling edge detection unit 17 are also reset to measure the temperature. The section 10 is deactivated and the display 15 displays a blank. Further, since the two inputs of the NAND gate 19 are both "H", the MCK.N signal becomes "H", and the oscillator 2, the counter 3 and the falling edge detector 18 are also reset.

At this time, since the MAX.R signal is not generated, the storage unit 1
1 is not reset, and the maximum temperature measurement value Nx so far is retained in the storage unit 11 as it is. This temperature measurement value Nx becomes the previous temperature measurement value for the next temperature measurement. Also, GRS
Even if the T2 signal is inverted from "L" to "H", the falling edge detection unit 18 does not generate the "L" MEM.phi. Signal. Therefore, the previous temperature measurement value Nx 'remains unchanged in the storage unit 12. Retained. However, this is not particularly important because the temperature measurement value held in the storage unit 11 is written in the storage unit 12 with the next operation of the switch 1.

As described above, when the switch 1 is operated longer than the 16n counting period of the counter after the operation of the temperature measuring unit 10 is started,
The previous display according to the measured temperature value is performed until the switch 1 is opened, and when the switch 1 is operated for a period shorter than the 16n counting period, the operation of the temperature measuring unit 10 is stopped. Therefore, even during temperature measurement, you can display the previous temperature measurement value at any time and for any period without stopping the temperature measurement operation. It will be easier.

In addition, in this embodiment, the operation duration of the switch 1 when the operation is started is not particularly significant. In the above description, the operation duration is set to the 16n count period or less of the counter 4, but the case where it is set to the 16n count period or more will be described with reference to FIG.

When the switch 1 is closed in the stop state, the output of the latch circuit 5 is inverted from "H" to "L" and the GRST1 and GRST2 signals are also changed from "H" to "L" as described above. Become. As a result, all the circuits are reset and the operation of the temperature measuring unit 10 is started, the multiplexer 13 selects the temperature measuring value from the storage unit 11, and the previous temperature measurement value Nx 'is written in the storage unit 12. Later, storage unit 1
1 is reset and the current temperature measurement value from the temperature measurement value 10 is written. Further, the display unit 15 lights up all the segments and displays “LO ° C.”, and then displays according to the current temperature measurement value written from the temperature measurement unit 10 to the storage unit 11.

Therefore, if the switch 1 is kept closed even after the counter 4 has counted 16n, the Q output of the counter 4 becomes "L".
To "H". However, since the GRST1 signal is "L", the G4 signal from the NAND gate 22 is kept at "H" as it is, and the latch circuit 6 is not set. Therefore, the Q output of the latch circuit 6 remains "L", and the multiplexer 13 selects the temperature measurement value from the storage unit 11 as it is. After that, even if switch 1 is opened,
The output of the latch circuit 5 is only inverted from "L" to "H" and does not affect the operation of other circuits.

After that, the switch 1 is closed for longer than the 16n counting period of the counter 4, so that the display 15
The display corresponding to the previous temperature measurement value Nx 'is displayed, and the switch 1
Is closed for a shorter period than the 16n counting period, all operations are stopped, as in the above description.

FIG. 4 is a block diagram showing another embodiment of the temperature measuring device according to the present invention, in which parts corresponding to those in FIG.

In the embodiment shown in FIG. 1, the reset terminal R of the latch circuit 6 is used.
The output of the latch circuit 5 is supplied to the latch circuit 5, but in this embodiment shown in FIG. 4, the GRST2 signal from the inverter 25 is supplied to the reset terminal R of the latch circuit 6 to operate the temperature measuring section 10. After starting, switch 1 to counter 4
If the switch is closed for longer than the 16n count period of, the display according to the previous temperature measurement value is displayed. In this display, the switch is closed for a shorter period than the 16n count period of the counter 4 and all circuits are closed. Continue until stopped. The operation of this embodiment will be described below with reference to FIGS. 5 (a) and 5 (b).

First, referring to FIG. 5 (a), when the switch 1 is operated to the closed state while all the circuits are reset, the oscillator 2, the counter and the falling edge detection section 18 are reset and the latch is released. The output of the circuit 5 is inverted from "H" to "L", and the GRST1 signal and the GRST2 signal are also inverted from "H" to "L". As a result, the counter 8, the control unit 9, the temperature measuring unit 10, the display decoder 14, the latch circuit 16 and the falling edge detecting unit 17 are reset and the temperature measuring unit 10 starts operating, and the falling edge detecting unit is started. The previous temperature measurement value Nx 'held in the storage unit 11 is written in the storage unit 12 by the MEM.phi. Signal from 18, and the storage unit 11 is reset by the MAX.R signal from the falling edge detection unit 17. .

Further, since the latch circuit 6 is released from reset by the GRST2 signal becoming "L", its Q output is "L", so the multiplexer 13 selects the temperature measurement value from the storage section 11. There is. The above state is maintained even when the switch 1 is opened.

The display unit 15 first resets the display decoder 14 and, at the same time, illuminates all the segments, and then displays "LO".
After the display of “° C.”, the temperature measurement value from the storage unit 11 is displayed.

The above operation is similar to that of the embodiment shown in FIG.

Next, when the switch 1 is closed again, the counter 4 and the latch circuit 5 are reset, and the output of the latch circuit 5 is inverted from "H" to "L". At the falling edge of this output, the counter 7 counts by 1 and GRST1
The signal changes from "L" to "H", but since the output of the latch circuit 5 is "L", the GRST2 signal remains "L". At this time, the Q output of the counter 4 is "L" and the G4 signal from the NAND gate 22 is "H".

When the switch 1 is kept closed for the 16n counting period of the counter 4 or more, when the counter 4 counts 16n, its Q output is inverted from "L" to "H", and the G4 signal from the NAND gate 22 becomes "H". "L" is inverted. At the falling edge of this G4 signal, the latch circuit 6 is set, and its Q output is inverted from "L" to "H". As a result, the multiplexer 13 selects the previous temperature measurement value Nx ′ from the storage unit 12, and the corresponding numerical value “Tx ′ ° C.” is displayed on the display unit 15.

At the rising edge of the Q output of the latch circuit 6, the counter 7 is reset, the GRST1 signal is inverted from "H" to "L", and the G4 signal from the NAND gate 22 is inverted from "L" to "H". However, the GRST2 signal remains "L".

After that, when the switch 1 is opened, the counter 4 and the latch circuit 5 are reset and the output of the latch circuit 5 is inverted from "L" to "H", but the counter 7 is not affected at all, so that the GRST1 signal is "L". ", So that the GRST2 signal also remains" L ". For this reason, the latch circuit 6 is not reset and the multiplexer 1
3 continues to select the previous temperature measurement value Nx 'from the storage unit 12.

In this way, even when the switch 1 is opened, the display unit 15 displays the numerical value "Tx '° C" corresponding to the previous temperature measurement value Nx'.

Next, in FIG. 5 (b), when the switch 1 is closed again, the counter 4 and the latch circuit 5 are reset, and the output of the latch circuit 5 is inverted from "H" to "L". Along with this, the counter 7 counts 1 and the GRS
The T1 signal is inverted from "L" to "H". However, since the output of the latch circuit 5 is "L", the GRST2 signal remains "L", the latch circuit 6 is not reset, and "Tx '° C" is displayed on the display unit 15.

If the switch 1 is opened before the counter 4 has counted 16n, the MCK.N signal is inverted from "L" to "H", the oscillator 2, the counter 3 and the rising edge detection 18 are reset, and the counter 4 and the latch are reset. The circuit 5 is also reset, and the output of the latch circuit 5 is inverted from "L" to "H". At the rising edge of this output, the GRST1 signal remains "H" and the GRST2 signal is inverted from "L" to "H" while the counter 7 is counting.

As a result, the latch circuit 6 is reset and its Q output is inverted from "H" to "L", and the counter 8, the control unit 9, the temperature measuring unit 10, the display decoder 14, the latch circuit 16 and the falling edge. The detection unit 17 is also reset and the temperature measurement unit 1
The operation of 0 is stopped, and the display 15 displays a blank.

Also in this embodiment, the upper work duration of the switch 1 for starting the operation may be longer or shorter than the 16n counting period of the counter 4, and the display may be made according to the temperature measurement value from the storage unit 11. It is similar to the embodiment shown in FIG. 1 that if the switch 1 is closed for a shorter period than the 16n counting period of the counter 4 while the display 15 is operating, all the operations are stopped. .

This point will be briefly described with reference to the timing chart of FIG. 6. When the switch 1 is closed while all the circuits are reset, the latch circuit 5 is set as described above. The output, GRST
“H” to “L” for both 1 signal and GRST2 signal
And the latch circuit 6 is released from reset,
The operation of the temperature measuring unit 10 is started, and the display 15 turns on all the segments. At this time, the Q output of the counter 4 is "L" and the G4 signal from the NAND gate 22 is "H".

When the switch 1 is continuously closed and the counter 4 then counts 16n, its Q output changes from "L" to "H".
However, since the GRST1 signal is "L", the G4 signal from the NAND gate 22 is "H" as it is, and the latch circuit 6 is not set. Therefore, the Q output is held at "L", the display 15 displays "LO ° C", and then displays according to the temperature measurement value from the storage unit 11.

Even if the switch 1 is opened and the counter 4 and the latch circuit 5 are reset, this state is maintained as it is, and the display unit 15 displays an indication according to the temperature measurement value from the storage unit 11.

Next, when the switch 1 is closed and the reset of the counter 4 and the latch circuit 5 is released, the counter 7 is set to 1 as the output of the latch circuit 5 is inverted from "H" to "L".
Counting, and the GRST1 signal is inverted from "L" to "H".

When the switch 1 is opened before the counter 4 counts 16n, the output of the latch circuit 5 changes from "L" to "H".
And the latch circuit 6 is not set,
The counter 7 is not preset and the GRST1 signal is held at "H" as it is. Therefore, when the output of the latch circuit 5 changes from “L” to “H”, GRST
The two signals are inverted from "L" to "H", the operation of the temperature measuring unit 10 is stopped, and the latch circuit 6 is reset.
When the switch 1 is opened, the MCK · N signal is inverted from “L” to “H”, and the oscillator 2 and the counter 3
It goes without saying that the falling edge detection unit 18 is reset.

As described above, in this embodiment, after the operation of the temperature measuring unit 10 is started, if the switch 1 is operated shorter than the 16n count period of the counter 4 16n counter 4, all the operations are stopped, but this 16n count period If the switch 1 is operated longer than that, the display according to the previous temperature measurement value is performed until the switch 1 is operated shorter than the next 16n counting period. Therefore, it is possible to check the previous temperature measurement value immediately after the maximum temperature of the desired temperature measurement value is found by performing sufficient temperature measurement, so it is necessary to compare both and to accurately grasp the tendency of temperature change. You can

In the case of this embodiment as well, it is needless to say that the maximum current measured value is held in the storage unit 11 even after all the operations are completed.

The embodiments of the present invention have been described above. However, these can start and stop the operation, and switch the display according to the temperature measurement value and the display according to the previous temperature measurement value by operating a single switch. Moreover, during the temperature measurement operation, the display according to the previous temperature measurement value can be displayed at any time and for any period, so that the current temperature measurement value and the previous temperature measurement value can be confirmed, compared, and the temperature change can be performed. It is possible to accurately and easily grasp the tendency of No. 1 by a simple operation, and in particular, there is no malfunction even when a woman or a woman uses it.

Further, at the start of the operation, all the segments of the display unit 15 are turned on, and then “LO ° C.” is displayed. Therefore, it is possible to confirm whether or not the display section operates normally by this, It can be confirmed that warming is performed, and the reliability of the displayed content is improved.

In addition, when the measured temperature value is outside the measurement range, fixed values, symbols, patterns, etc. are displayed, so meaningless temperatures outside the measurement range are displayed to allow the user to make unnecessary judgments. It is possible to prevent this, and in this case, since different numerical values, symbols, and patterns are displayed between the all-time temperature measurement value and the current temperature measurement value, the display according to which temperature value is displayed. It is possible to clearly distinguish whether it is the period during which

In the above embodiment, if the period for counting 1 by the counter 8 is about 0.7 seconds, the lighting period of all the segments of the display 15 is about 1.4 seconds, and it is possible to fully recognize that all the segments are lit at this level. . However, the numerical values and the specific numerical values used in the above description are merely examples, and the present invention is not limited to these numerical values.

Further, in the above embodiment, the previous temperature measurement value Nx ′ is written from the storage unit 11 to the storage unit 12 when the operation of the temperature measurement unit 10 is started, but instead of the falling edge detection unit 18, the rising edge detection unit 18 is used. The GRST2 signal is delayed and supplied to this reset terminal, and the MEM / φ signal is formed at the falling edge of the GRST2 signal. It is also possible to write the held temperature measurement value Nx in the storage unit 12 and use it as the previous temperature measurement value in the next temperature measurement.

〔The invention's effect〕

As described above, according to the present invention, not only can the operation be started and stopped by operating a single switch, but also the operation duration of the switch can be lengthened even during the temperature measurement operation. It is possible to select the display according to the previous temperature measurement value instead of the display according to the current temperature measurement value with a simple operation, the operation is extremely simple and the handling is extremely easy, and moreover, It is possible to obtain an excellent effect that the configuration is simple and the size can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the temperature measuring device according to the present invention, FIGS. 2 (a), (b) and 3 are timing charts for explaining the operation of FIG. 1, FIG. FIG. 5 is a block diagram showing another embodiment of the temperature measuring device according to the present invention, FIGS. 5 (a), 5 (b) and 6 are timing charts for explaining the operation of FIG. 1 ... Switch, 4 ... Counter, 5,6 ... Latch circuit, 7,8 ... Counter, 10 ... Temperature measuring section, 11,12
...... Memory section, 13 ...... Multiplexer, 15 ...... Display.

Continuation of front page (72) Inventor Isao Imagawa 4680 Ikata, Hachijo-machi, Tagawa-gun, Fukuoka Prefecture Within Kyushu Hitachi Maxell Co., Ltd. (56) Reference JP-A-58-46723 (JP, A) JP-A-56- 158640 (JP, A) JP-A-60-42625 (JP, A)

Claims (1)

[Claims] 1. A switch that can be operated from the outside, a first determination unit that determines the opening / closing operation state of the switch, a temperature measurement unit that starts operation in response to the output of the first determination unit, and the temperature measurement unit. A first storage unit that holds temperature measurement data of the temperature unit, and a second storage unit in which the measurement data held in the first storage unit is written when the operation of the temperature measurement unit starts or ends. And a second determination unit for determining whether the operation duration of the switch operated after the operation of the temperature measurement unit is long or short, and continuing or stopping the operation of the temperature measurement unit according to the output of the second determination unit. A selection unit for selecting the measurement data, a multiplexer for selecting the measurement data read from the first and second storage units according to the output of the second determination unit, and a measurement data selected by the multiplexer. A display unit for displaying the above, and after the operation of the temperature measuring unit is started, the first The storage unit holds the current measurement data by the temperature measurement unit, the second storage unit holds the previous measurement data by the temperature measurement unit, and displays a display corresponding to the current measurement data on the display unit. It is configured such that switching to display according to previous measurement data and stop of operation of the temperature measuring unit can be selected depending on the length of the operation time of the switch after the operation of the temperature measuring unit. And a temperature measuring device.