JPH09220165A - Liquid container with temperature indication function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to indicate appropriate liquid temperatures without causing any faulty action, even if a solar cell of small current capacity is used. SOLUTION: The temperatures of a liquid stored in a liquid container 8 are indicated on an indicator part based on a detection signal from a temperature detecting means. Next, the detection signal is entered to a system resetting IC 5 using the temperature detecting means, and an output signal from the system resetting IC 5 is inputted to the setting terminal S of a latch circuit 6a for liquid temperature detection. Further a pulse signal sent from an oscillation circuit 2 is inputted to the resetting terminal R of the latch circuit 6a for liquid temperature detection. Consequently, temperatures are indicated on the indicator part based on an electric power supplied from a solar cell 1 through the latching circuit 6a for liquid temperature detection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid container such as a pot or a water bottle having a temperature display function capable of displaying the liquid temperature of the liquid contained in the display unit based on the electric power supplied from the solar cell. It relates to a liquid container.

[0002]

2. Description of the Related Art Conventionally, a liquid container such as a pot which does not use an external power source is disclosed in Japanese Patent Publication No. 4-43647, which is capable of displaying the temperature of hot water contained therein. This relates to a pot having a liquid display function, and discloses a pot using a temperature sensor in order to solve the drawback of the liquid temperature display using a thermometer or a bimetal. More specifically, the pot uses a comparator to compare a detection signal from the temperature sensor with a reference signal to perform a predetermined display on the display unit.

[0003]

However, the current consumption of the comparator used in the pot is about 200 μA.
Since it is necessary, the supply current is several tens of microamperes like solar cells.
The one (when the brightness is 200 Lx) cannot be used and requires another power source such as a battery. For this reason, there is a problem that a troublesome work such as replacing the battery has to be performed. Further, even if a power source with a small current capacity such as a solar cell can be used, the IC circuit is easily affected by external noise, so that there is a risk of malfunction, and measures for that are necessary. Further, the solar cell has a problem that the supply voltage fluctuates and it is difficult to use it for temperature detection.

Therefore, it is an object of the present invention to provide a liquid container with a temperature display function capable of displaying an appropriate liquid temperature without causing a malfunction even when a solar cell having a small current capacity is used.

[0005]

In order to achieve the above object, in the present invention, a liquid container with a temperature display function is arranged to display the liquid temperature in the liquid container on a display portion based on a detection signal of the temperature detection means. In the above, a temperature display circuit driven by a solar cell is provided, and the temperature display circuit outputs a pulse signal, a system reset IC that determines a liquid temperature based on a detection signal of the temperature detection means, A latch circuit for inputting an output signal from a system reset IC to a set terminal and a pulse signal from the oscillation circuit to a reset terminal to cause the display unit to display a temperature. is there.

In the system reset IC, despite being a solar cell having a small current capacity, the detection signal from the temperature detecting means is accurately discriminated and an output signal is issued to the set terminal of the latch circuit. The latch circuit is constantly reset by the pulse signal from the oscillation circuit input to the reset terminal. As a result, even if the external noise is adversely affected, the original state is instantly restored and no malfunction occurs. Then, according to the input signal from the system reset IC, a predetermined temperature is displayed on the display unit.

The temperature detecting means comprises a thermistor,
As the system reset IC, it is possible to use one that switches the output signal to the set terminal of the latch circuit when the input voltage drops below a predetermined value in accordance with the voltage drop accompanying the increase in the electric resistance value of the thermistor due to the change in liquid temperature. Is.

It is preferable that the resistance combined with the thermistor is also used as the internal resistance of the system reset IC.

It is preferable that the power supplied from the solar cell is supplied through a Zener diode connected in parallel. Even if the supply voltage from the solar cell fluctuates, the fluctuation range can be suppressed sequentially by the Zener diode.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) In the liquid container with a temperature display function according to the first embodiment, the water temperature / water level of the contained water can be detected by the water temperature / water level detection circuit shown in FIG. Has become.

This water temperature / water level detection circuit generally includes a solar cell 1, an oscillation circuit 2, a one-shot multivibrator 3, a thermistor 4, a system reset IC 5,
It is composed of latch circuits 6a, 6b and 6c.

The solar cell 1 has a capacitor C and a resistor R ₁
And Zener diode ZD ₁ are connected in parallel, the positive pole thereof is connected to the _Vcc terminal of the one-shot multivibrator 3, and the negative pole thereof is connected to the reference terminal of the LCD 7 and the GND terminal of the one-shot multivibrator 3, respectively. There is.

The oscillator circuit 2 oscillates a pulse signal (rectangular wave) whose oscillation frequency is set to 100 Hz, outputs the pulse signal from the first output terminal a and the second output terminal b, respectively, and inverts this. The pulse signal is output from the third output terminal c. This oscillation frequency is the same as the operating frequency when the LCD 7 is statically driven. This allows
A drive circuit dedicated to the LCD 7 is unnecessary, and the number of parts can be reduced.

The input terminal of the one-shot multivibrator 3 is connected to the second output terminal b of the oscillation circuit 2, and the output terminal of the one-shot multivibrator 3 is provided on the bottom of the liquid container 8.
It is connected to a and outputs a pulse signal synchronized with the on-edge of the pulse signal from the second output terminal b of the oscillation circuit 2.

The thermistor 4 is arranged in the liquid container 8 (in FIG. 1, it is shown at a position separated from the liquid container 8 for simplification), and one terminal is connected via resistors R ₁ and R _2. It is connected to the positive pole of the solar cell 1, and the other terminal is connected to the _Vcc terminal of the system reset IC 5. Here, the one whose output becomes low when the liquid temperature becomes 70 ° C. or lower is used.

The system reset IC 5 is originally an element for monitoring the input voltage to prevent malfunction of the microcomputer (for example, Mitsumi Electric Co., Ltd .; PST9011, etc. can be used). The internal configuration will be described. As shown in FIG. 2, two operational amplifiers 10a, 10b and 2 are provided.
It has two transistors Tr ₁ and Tr ₂ . Negative input terminal of the operational amplifier 10a is connected to the midpoint of the resistors R _3, R _4, which are internally connected between V _cc and GND, the positive input terminal is connected to the low voltage circuit 11. On the other hand, the output terminal of the operational amplifier 10a is connected to the base of the transistor Tr ₁ via a resistor R _5, are connected to the negative input terminal of the operational amplifier 10b the collector of the transistor Tr ₁ is connected through a resistor R _6. The output terminal of the operational amplifier 10b is connected to the base of the transistor Tr ₂ via the resistor R _7. Transistor T
The collector of r ₂ and the positive input terminal of the operational amplifier 10b are connected to the output terminal V _out of the system reset IC 5, and the emitters of the transistors Tr ₁ and Tr ₂ are grounded.

System reset I having such a circuit configuration
C5 is connected to the positive pole of the solar cell 1 and the output terminal V _out through the resistor R _8, is connected to the set terminal S of the latch circuit 6a, GND (ground) terminal minus pole of the solar cell 1 It is connected to the. Further, as described above, since the V _cc terminal is connected to the thermistor 4 and the resistor R ₂ , it is input to the V _cc terminal by dividing the combined resistance of the thermistors 4 and R ₂ and the internal resistance of the system reset IC 5. The voltage value to be applied is determined. Since the system reset IC 5 can detect the change in the input voltage with the voltage of 1.1 V as a reference value, the system reset IC 5 can be used as a normal voltage comparator, and its low power consumption can be achieved. It can be used for detecting the liquid temperature of a solar cell because of its excellent properties.

The latch circuit 6a is for detecting the liquid temperature, and the latch circuits 6b and 6c are for detecting the water level.

In the liquid temperature detecting latch circuit 6a, the set terminal S has an output terminal V of the system reset IC 5.
_out is connected to the reset terminal R.
The output terminal a is connected. As a result, the liquid temperature detection latch circuit 6a can reset the input signal from the system reset IC 5 at a cycle of 1/100 second based on the pulse signal from the oscillation circuit 2. Therefore, even if the system reset IC 5 or the like malfunctions due to the influence of external noise, the liquid temperature detection latch circuit 6a is instantly reset, so that the LCD 7 is not erroneously displayed.

On the other hand, in the water level detecting latch circuits 6b and 6c, the set terminal S thereof has a first measuring electrode 9b and a second measuring electrode 9c which are arranged above and below the liquid container 8, respectively.
Are connected to the reset terminal R and the oscillation circuit 2
The third output terminal c of is connected. As a result, when the water level of the water contained in the liquid container 8 is full above the second measurement electrode 9c, the pulse signal from the one-shot multivibrator 3 is synchronized with the pulse signal from the oscillation circuit 2. It is input to each water level detection latch circuit 6b, 6c, and an output signal is obtained from both. If the water level is in an intermediate state between the first measurement electrode 9b and the second measurement electrode 9c, the pulse signal is input only to the set terminal S of the lower second water level detection latch circuit 6c, and the second An output is obtained only from the water level detection latch circuit 6c. further,
When the liquid container 8 is empty, no output is obtained from any of the water level detection latch circuits 6b and 6c.

As shown in FIG. 3, the LCD 7 has a water temperature display section 12 (a portion representing steam is lit or extinguished) indicating whether or not the temperature of the contained water exceeds a predetermined temperature. A water level display section 13 having two upper and lower display sections 13a and 13b having a shape similar to the side view of the liquid container 8.
And is disposed on the upper front surface of the liquid container 8, for example.

The water temperature / water level detection circuit having the above-mentioned configuration detects the water temperature as follows. That is, when hot water is poured into the liquid container 8 and the temperature thereof exceeds the set temperature (for example, 70 ° C.), the electric resistance value of the thermistor 4 becomes low, and the combined resistance of the thermistor 4 and the resistor R ₂ and the system The voltage division with the internal resistance of the reset IC5 becomes high and the reference voltage
It becomes more than 1.1V. As a result, the system reset IC5
Goes high.

When the temperature of the hot water contained in the liquid container 8 falls below the set temperature due to the passage of time, the electric resistance value of the thermistor 4 rises,
As shown in FIG. 4, the voltage input to the _Vcc terminal of the system reset IC 5 drops. As a result, the input voltage becomes lower than the reference voltage, and the output from the system reset IC 5 becomes low.

As a result, in the liquid temperature detecting latch circuit 6a, as shown in FIG. 5, when the output from the system reset IC 5 is high, the pulse signal from the oscillation circuit 2 input to the reset terminal R is inputted. The output becomes high while being reset at a cycle of 1/100 second, and the water temperature display portion 12 of the LCD 7 is turned on. When the liquid temperature decreases and the output from the system reset IC 5 becomes low, the output from the output terminal becomes low and the water temperature display section 12 is turned off.

On the other hand, the water temperature / water level detection circuit having the above-mentioned configuration detects the water level as follows. That is, if hot water is poured into the liquid container 8 and the water level is located above the first measurement electrode 9b, as shown in FIG.
Since the "a" and the first measuring electrode 9b and the second measuring electrode 9c are electrically connected, the water level detecting latch circuits 6b, 6c are provided.
One-shot multi-vibrator 3 for set terminal S of
The pulse signal from is input. This allows the LCD 7
Both the display units 13a and 13b of the water level display unit 13 are turned on.

If the water level decreases due to use, the reference electrode 9, the first measuring electrode 9b, and the second measuring electrode 9c are sequentially arranged.
6B, the insulating state is formed in this order, and as shown in FIG. 6B, the first water level detection latch circuit 6b and the second water level detection latch circuit 6c are no longer output pulse signals in this order, and
The corresponding part of CD7 goes out. As a result,
It is possible to determine which range of the liquid container 8 the water level is, that is, more than half, less than half, or empty.

In the above embodiment, only one system reset IC 5 is provided so that the liquid temperature can be displayed only in two stages, but the number of liquid temperatures can be further increased so that the liquid temperature can be displayed in a plurality of stages. It may also be used to detect cold water.

Further, in the above embodiment, the first measuring electrode 9b, the second measuring electrode 9c and the corresponding first water level detecting latch circuit 6b and second water level detecting latch circuit 6c are provided to change the water level. Although it is possible to recognize in three modes of half or more, half or less, and sky, it is also possible to further subdivide to detect the water level. However, in this case, the measurement electrode and the water level detection latch circuit are required for each water level desired to be detected.

(Second Embodiment) In a liquid container with a temperature display function according to a second embodiment, the temperature of water contained can be detected by a temperature detection circuit shown in FIG.

This temperature display circuit is different from that of the first embodiment in that three Zener diodes ZD are provided for the solar cell 1.
₁ , ZD ₂ and ZD ₃ are connected in parallel and each Zener diode Z
The difference is that resistors R ₉ and R ₁₀ are connected between D ₁ and ZD _{2 and} between ZD ₂ and ZD ₃ . Zener diode ZD ₁ , Z used
As D ₂ and ZD ₃ , for example, a silicon planar type (manufactured by NEC Corporation; RD-HS series or the like) having a relatively stable zener voltage even when the zener current is small is preferable.

Thus, the Zener diodes ZD ₁ and ZD
Since D ₂ and ZD ₃ are connected in parallel, the zener voltage is stabilized by the zener diodes ZD ₁ , ZD ₂ and ZD ₃ sequentially even if the supply voltage / current from the solar cell 1 fluctuates due to changes in brightness. . Specifically, Zener diodes ZD ₁ and Z
When RD-2.7HS manufactured by NEC is used for D ₂ and ZD ₃ , the resistance R ₁ is set to 250 KΩ, and the resistances R ₉ and R ₁₀ are set to ₁₀₀ KΩ, the supply voltage changes (2.5 to 5 V). Zener voltage obtained by the Zener diode ZD _1, ZD _2, ZD _3, as shown in FIG. 8, eventually 1.91 to 1.
It was 96V, and the fluctuation range could be suppressed to 0.05V.

In the second embodiment, the three zener diodes ZD ₁ , ZD ₂ and ZD ₃ are connected in parallel, but the number is not limited. However, in actuality, considering the voltage drop and the like, about three is appropriate.

[0034]

As is apparent from the above description, according to the liquid container with a temperature display function of the present invention, the system reset IC can be applied even when the solar cell having a small current capacity is used. The temperature can be properly displayed by.

Further, since the latch circuit is used to frequently reset the display on the display portion again on the basis of the pulse signal from the oscillation circuit, an external noise does not cause a malfunction.

Furthermore, since the supply voltage from the solar cell is supplied to the system reset IC via a plurality of Zener diodes connected in parallel, the fluctuation range of the supply voltage is reduced, and more stable temperature detection is possible. Becomes

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a temperature display circuit of a liquid container according to a first embodiment.

FIG. 2 is a circuit diagram of the system reset IC shown in FIG.

FIG. 3 is a front view of the LCD shown in FIG.

FIG. 4 is a graph showing a relationship between inputs and outputs of the system reset IC of FIG.

5 is a graph showing the relationship between the input and output of the liquid temperature detection latch circuit of FIG. 1. FIG.

6 is a graph showing the relationship between the input and output of the water level detection latch circuit of FIG.

FIG. 7 is a circuit diagram showing a temperature display circuit for a liquid container according to a second embodiment.

8 is a table showing Zener voltages obtained by the Zener diodes in FIG.

[Explanation of symbols]

 1 Solar Cell 2 Oscillation Circuit 4 Thermistor 5 System Reset IC 6a Liquid Temperature Detection Latch Circuit 6b, 6c Water Level Detection Latch Circuit 7 LCD 8 Liquid Container 12 Water Temperature Display

Claims (4)

[Claims] 1. A liquid container with a temperature display function, wherein a liquid temperature in the liquid container is displayed on a display unit based on a detection signal of a temperature detection means, the liquid container having a temperature display circuit driven by a solar cell, The temperature display circuit inputs an oscillation circuit that outputs a pulse signal, a system reset IC that determines the liquid temperature based on the detection signal of the temperature detection unit, and an output signal from the system reset IC to a set terminal. By inputting the pulse signal from the oscillation circuit to the reset terminal,
A liquid container with a temperature display function, comprising: a latch circuit that causes the display unit to display a temperature. 2. The temperature detecting means comprises a thermistor, and the system reset IC latches if the input voltage drops below a predetermined value according to a voltage drop accompanying an increase in an electric resistance value of the thermistor due to a change in liquid temperature. The liquid container with a temperature display function according to claim 1, wherein the output signal to the set terminal of the circuit is switched. 3. The liquid container with a temperature display function according to claim 2, wherein a resistance combined with the thermistor is also used as an internal resistance of the system reset IC. 4. The liquid container with a temperature display function according to claim 1, wherein the power supplied from the solar cell is supplied through a Zener diode connected in parallel. .