JP3612376B2 - Power supply circuit with backup battery and liquid container with display function provided with the circuit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a driving circuit for a solar cell that is used to display the temperature and water level of water stored in a pot or thermos that does not require an external power source by using power supplied from the solar cell.
[0002]
[Prior art]
Conventionally, in a thermos or the like, it is possible to display the temperature and the water level of water stored by using power supplied from a battery or the like. For example, (1) Japanese Utility Model Publication No. 61-12021, (2) Japanese Fairness 2 -43302 and (3) Japanese Utility Model Publication No. 4-43647.
[0003]
In (1), electrodes are arranged at the center and the outer periphery of the liquid container, respectively, and the LED is turned on by detecting the change in capacitance between the two electrodes due to the difference in water level by the power supplied from the battery. It is a thing.
[0004]
The (2) is devised so that the solar cell is installed in the most convenient place for condensing and the lead wire to the liquid amount display unit can be made the shortest. The liquid amount is displayed based on the change in the capacitance between the electrodes.
[0005]
In the case of (3), as in the cases (1) and (2), the liquid amount is displayed based on the change in the capacitance between the two electrodes. However, the liquid level is displayed by discharging the capacitor composed of both electrodes and counting the number of charging pulses while the terminal voltage drops to the reference voltage, and a battery is used as the power source. .
[0006]
[Problems to be solved by the invention]
However, in the above (1), there is a problem that a separate battery is required and it takes time and effort for replacement.
[0007]
In (2), since the supply voltage of the solar cell fluctuates due to the difference in ambient brightness, the thermos cannot be reliably displayed and has not yet been put into practical use. In addition, since the electric capacity of the solar cell is small, the negative lead wire of the liquid amount display unit is grounded to the exterior case in order to avoid the IC circuit from being affected by external noise. However, once the IC circuit malfunctions due to the influence of noise, there is a problem that the display on the liquid amount display unit remains as it is.
[0008]
Furthermore, in (3), since the water level is detected by discharging a capacitor composed of both electrodes, the power consumption is large, and a solar cell with a small electric capacity cannot be used.
[0009]
Therefore, the present invention causes a malfunction regardless of a power supply circuit with a backup battery capable of maintaining a stable supply voltage while effectively using power supplied from a solar battery, regardless of a low supply voltage from the circuit. It is an object of the present invention to provide a liquid container with a display function capable of performing appropriate display without any problem.
[0010]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides a power supply circuit with a backup battery,
A backup battery,
Solar cells,
Power replenishing means for supplying power from the backup battery by lowering the voltage value input from the solar battery lower than the minimum driving minimum required for driving other circuits;
A power supply stopping means for stopping the supply of power from the backup battery when the voltage value input from the solar battery falls below a driving unnecessary value lower than the minimum driving value ;
The power replenishing means maintains an off state if the voltage value input to the base from the solar cell is equal to or higher than the minimum driving value necessary for driving other circuits, and turns on if the voltage value is lower than the minimum driving value. A second transistor in a state,
Connecting the emitter of the second transistor to the base of the first transistor, connecting the emitter of the first transistor to the positive pole of the backup battery, and connecting the collector of the first transistor to the positive pole of the solar battery. Thus, if the second transistor maintains the off state, the first transistor also maintains the off state to supply power from the solar cell and stop supplying power from the backup battery, while the second transistor Is turned on, the first transistor is turned on to supply power from the backup battery in addition to the solar battery,
The power supply stopping means maintains an off state when a voltage value input to the base from the solar cell falls below a driving unnecessary value lower than the driving minimum value, and an on state if the driving value is equal to or higher than the driving minimum value. The third transistor is
If the third transistor is turned off by connecting the collector of the third transistor to the negative electrode of the solar battery and the backup battery and connecting the emitter to the collector of the second transistor, the second transistor and the first transistor In this configuration , the power supply from the backup battery is forcibly turned off sequentially and stopped .
[0011]
It is preferable to include power supply stopping means for stopping the supply of power from the backup battery when the voltage value input from the solar battery falls below a driving unnecessary value lower than the minimum driving value. In this case, when the amount of light is further reduced and power supply is considered unnecessary, the power supply from the backup battery is forcibly stopped by the power supply stop unit. As a result, the life of the backup battery can be further extended.
[0012]
Moreover, in order to achieve the said subject, while displaying the liquid container with a display function with the electric power supplied from the power supply circuit with a backup battery of the said Claim 1 or 2, a display part is based on the detection signal of a water level detection means. A water level display circuit for displaying a water level, the water level display circuit having an oscillation circuit for outputting a pulse signal, a detection signal of the water level detection means being inputted to a set terminal, and a pulse signal of the oscillation circuit being inputted to a reset terminal. A latch circuit that displays the water level on the display unit when input is provided.
[0013]
In this liquid container, the power supply circuit with the backup battery automatically replenishes the power from the backup battery when the supply voltage from the solar battery is not stable, so that the constant voltage is maintained and a malfunction occurs in the display unit. There is no. In particular, even if it is adversely affected by external noise, a pulse signal is input from the oscillation circuit to the reset terminal of the latch circuit so that it is always reset. Thus, a stable display operation can be performed.
[0014]
Furthermore, in order to achieve the said subject, while driving with the electric power supplied from the power supply circuit with a backup battery of the said Claim 1 or 2, the liquid temperature in a liquid container is displayed based on the detection signal of a temperature detection means. The temperature display circuit includes an oscillation circuit that outputs a pulse signal, a system reset IC that determines a liquid temperature based on a detection signal of the temperature detection unit, and a circuit from the system reset IC. An output signal is input to the set terminal, and a pulse circuit from the oscillation circuit is input to the reset terminal, thereby providing a latch circuit that displays the temperature on the display unit.
[0015]
Even in this liquid container, as described above, a constant voltage can be maintained by the power supply circuit with a backup battery and the latch circuit, so that no malfunction occurs in the display unit. In addition, by using the system reset IC as a voltage comparator, it is possible to achieve a further excellent effect of preventing malfunction in the display unit in that a liquid temperature determination unit with low power consumption can be configured.
[0016]
If the power supplied from the power supply circuit with the backup battery to the water temperature determination circuit is supplied via a Zener diode connected in parallel, the change in the backup battery electromotive force due to the change in the room temperature can be reduced, and the water temperature can be determined. The error can be reduced.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0018]
(First Embodiment) FIG. 1 shows a water level / water temperature detection circuit provided with a power circuit 1 according to the present invention and provided in a liquid container 11. The oscillation circuit 3, the one-shot multivibrator 4, and the water level determination circuit 5 are configured.
[0019]
The power supply circuit 1 is provided with a solar battery 6 and a backup battery 7. A capacitor C is connected in parallel to the solar cell 6 so as to smooth the supply voltage. Further, the positive pole of the solar cell 6, _{V CC} terminal of the one-shot multivibrator 4 via the diode _{D 1, V OUT} terminal of the system reset IC9 the first transistor Tr ₁ of the collector, and via a resistor _{R 11} to the following And is connected to the base of the second transistor Tr ₂ which is a power supplement means via the diode D ₂ and the resistor R ₁ . Further, the negative electrode of the solar cell 6 is connected to a reference terminal of each display unit 14 and 15 of the LCD 13 described below, a GND terminal of the one-shot multivibrator 4, and a GND terminal of the system reset IC 9. While the the second transistor Tr ₂ emitter the first base of the transistor Tr ₁ is connected, the resistor R ₃ and a backup battery 7 is connected in parallel between the emitter and the collector. The supply voltage from the power supply circuit 1 to the temperature judging circuit 5 is adapted to constant voltage is achieved by the resistor R ₄ and the Zener diode ZD.
[0020]
The water temperature determination circuit 2 includes a thermistor 8, a system reset IC 9, and a water temperature detection latch circuit 10a.
[0021]
The thermistor 8 is disposed in the liquid container 11 (in FIG. 1, it is shown at a position away from the liquid container 11 for simplicity), and one terminal is a solar cell via resistors R ₄ and R _5. It is connected to a positive pole, and the other terminal is connected to the V _CC terminal of the system reset IC 9. Here, the one whose output voltage becomes low when the liquid temperature becomes 70 ° C. or lower is used.
[0022]
The system reset IC 9 is originally an element for monitoring the input voltage and preventing a 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 100a and 100b and two transistors Tr ₁₀₁ and Tr ₁₀₂ are provided. The negative input terminal of the operational amplifier 100 a is connected to the middle point of the resistors R ₆ and R ₇ internally connected between the _VCC terminal and the GND terminal, and the positive input terminal is connected to the low voltage circuit 11. On the other hand, the output terminal of the operational amplifier 100a is connected to the base of the transistor _{Tr 101} via a resistor _{R 8,} and is connected to the negative input terminal of the operational amplifier 100b collector of the transistor _{Tr 101} via a resistor _{R 9.} The output terminal of the operational amplifier 100b is connected to the base of the transistor _{Tr 102} via the resistor _{R 10.} Collector and the positive input terminal of the operational amplifier 100b of the transistor _{Tr 102} is connected to the output terminal _{V OUT} of the system reset IC 9, the emitter of the transistor _{Tr 101, Tr 102} is connected to the ground.
[0023]
System reset IC9 of such a circuit arrangement is connected to the positive pole of the solar cell 6 and the output terminal _{V OUT} through the resistor _{R 11,} is connected to the set terminal S of the latch circuit 10a, GND (ground) The terminal is connected to the negative electrode of the solar cell 6. Further, as described above, since the V _CC terminal is connected to the thermistor 8 and the resistor R _5, the thermistor 8, the combined resistance of the resistor R _5, the V _CC terminal by the partial pressure of the internal resistance of the system reset IC9 The input voltage value is determined. Since the system reset IC 9 can detect a change in the input voltage with a voltage of 1.1V as a reference value, the system reset IC 9 can be used as a normal voltage comparator, and its low consumption. It can be used for displaying the liquid temperature of the solar cell 6 from the viewpoint of power.
[0024]
The oscillation circuit 3 oscillates a pulse signal (rectangular wave) whose oscillation frequency is set to 100 Hz and a pulse signal inverted thereto from the first output terminal a and the second output terminal b, respectively. This oscillation frequency is the same as the operation frequency when the LCD 13 is statically driven. As a result, a drive circuit dedicated to the LCD 13 is not required, and the number of components can be reduced.
[0025]
As shown in FIG. 3, the LCD 13 includes a water temperature display unit 14 (a portion representing steam is turned on or off) indicating whether or not the temperature of the stored water exceeds a predetermined temperature, and the side surface of the liquid container 11. The water level display unit 15 is composed of two display units 15 a and 15 b having a shape similar to that shown in the figure, and is disposed, for example, on the upper front surface of the liquid container 11. In the water level display portions 15a and 15b, when both are lit, the water level is more than half, when the lower display portion 15b is lit, the water level is less than half, and when both are not lit, 400CC or less is indicated. When 15b is turned off, the characters "hot water supply" printed and displayed there can be recognized.
[0026]
The one-shot multivibrator 4 has an input terminal connected to the second output terminal b of the oscillation circuit 3, and an output terminal connected to a reference electrode 16 a provided on the bottom of the liquid container 11. A pulse signal synchronized with the on-edge of the pulse signal from the second output terminal b is output.
[0027]
The water level determination circuit 5 includes a reference electrode 16a disposed on the bottom of the liquid container 11, a first measurement electrode 16b and a second measurement electrode 16c disposed on the top and bottom, and a first water level detection latch circuit. 10b and a second water level detection latch circuit 10c.
[0028]
As the first and second water level detection latch circuits 10b and 10c, so-called NOR latches are used as in the case of the liquid temperature detection latch circuit 10a, and the output terminals of the display units 15a and 15b of the water level display unit 15 of the LCD 13 are used. Are connected to one of the terminals. The first measurement electrode 16b provided at the bottom of the liquid container 11 is connected to the set terminal S of the first water level detection latch circuit 10b, and the set terminal S of the second water level detection latch circuit 10c is connected to the intermediate portion. The provided second measurement electrode 16c is connected. Further, the first output terminal a of the oscillation circuit 3 is connected to the reset terminal R of each of the latch circuits 10b and 10c. Furthermore, the first and second measuring electrodes 16b, 16c are connected respectively to the first, the negative pole of the solar cell 6 via a second resistor _{R 12, R 13.}
[0029]
In the water level / water temperature detection circuit configured as described above, the supplied power is switched between the solar battery 6 alone and both the solar battery 6 and the backup battery 7, and the water temperature and the water level are detected.
[0030]
(Battery switching) For example, when the brightness is 100 Lx or more, such as when used in the daytime, the supply voltage from the solar battery 6 is 2.5 V or more, so the second transistor Tr ₂ is turned off. . Thus, the voltage equal between the base and emitter of the first transistor Tr _1, the first transistor Tr ₁ is kept off, no current flows from the backup battery 7.
[0031]
If the brightness is less than 100 Lx, such as when the room lighting is dark in the evening or at night, the supply voltage from the solar cell 6 becomes less than the minimum driving value (for example, 2.5 V), and the second transistor Tr ₂ is turned on. It becomes a state. As a result, current flows from the backup battery 7 to the resistors R ₃ and R ₂ , and the voltage drops at the resistor R ₃ . The first transistor Tr ₁ is turned on when the base voltage decreases, and power is supplied not only from the solar battery 6 but also from the backup battery 7 to the circuit.
[0032]
As a result, the supply voltage from the power supply circuit 1 is always kept constant regardless of changes in ambient brightness, the driving state of the water level / water temperature detection circuit is stabilized, and the LCD 13 can be appropriately connected without causing malfunction. A predetermined display can be performed.
[0033]
(Detection of water temperature) The water temperature / water level detection circuit configured as described above detects the water temperature as follows. That is, when hot water is poured into the liquid container 11 and the temperature exceeds a set temperature (for example, 70 ° C.), the electrical resistance value of the thermistor 8 becomes low, the combined resistance of the thermistor 8 and the resistor R ₅ , and the system The divided voltage with the internal resistance of the reset IC 9 becomes high and becomes 1.1 V or more which is a reference voltage. As a result, the output from the system reset IC 9 becomes high.
[0034]
When the temperature of the hot water stored in the liquid container 11 decreases and becomes lower than the set temperature due to the passage of time or the like, the electrical resistance value of the thermistor 8 increases, as shown in FIG. voltage input to the _{V CC} terminal of the reset IC9 falls. As a result, the input voltage becomes less than the reference voltage, and the output from the system reset IC 9 becomes low.
[0035]
In the liquid temperature detection latch circuit 10a, as shown in FIG. 5, when the output from the system reset IC 9 is high, the pulse signal from the oscillation circuit 2 inputted to the reset terminal R is 1/100 second. The output becomes high while being reset at the period of, and the water temperature display 14 of the LCD 13 is turned on. When the liquid temperature falls and the output from the system reset IC 9 becomes low, the output from the output terminal becomes low and the water temperature display unit 14 is turned off.
[0036]
(Detection of water level) If hot water is poured into the liquid container 11 and the water level is located above the first measurement electrode 16b, as shown in FIG. 6 (a), the reference electrode 16a, the first measurement electrode 16b, and Since the connection with the second measurement electrode 16c is in a conductive state, a pulse signal from the one-shot multivibrator 4 is input to the set terminals of the water level detection latch circuits 10b and 10c. Thereby, both the display parts 15a and 15b of the water level display part 15 of LCD13 are lighted.
[0037]
In addition, if the water level decreases due to use, an insulating state is formed in the order between the reference electrode 16a, the first measurement electrode 16b, and the second measurement electrode 16c, as shown in FIG. No pulse signal is output in the order of the first water level detection latch circuit 10b and the second water level detection latch circuit 10c, and the corresponding portion of the LCD 13 is turned off. As a result, it is possible to determine in which range of the liquid container 11 the water level is currently, that is, half or more, half or less, or 400 cc or less.
[0038]
In the first embodiment, only one system reset IC 9 is provided so that the liquid temperature can be displayed only in two stages. However, the number of the liquid temperatures may be increased and displayed in a plurality of stages. Moreover, you may utilize for the detection of cold water.
[0039]
In the first embodiment, the first measurement electrode 16b, the second measurement electrode 16c, the corresponding water temperature detection latch circuit 10a, and the first water level detection latch circuit 10b are provided so that the water level is more than half. However, it is possible to recognize in three modes of less than half and 400 cc or less, but it is also possible to further subdivide and detect the water level. However, in this case, a measurement electrode and a latch circuit are necessary for each water level desired to be detected.
[0040]
(Second Embodiment) FIG. 7 shows a water level / water temperature detection circuit according to a second embodiment, and the first embodiment is a third transistor Tr which is a power supply stop means. ₃ is different. That is, the third transistor Tr ₃ has a base connected between the resistors R ₁₄ and R ₁₅ connected in parallel to the solar cell 6, and a collector connected to the collector of the second transistor Tr ₂ via the resistor R _2. The emitter is connected to the negative electrode of the solar cell 6.
[0041]
In this water level / water temperature detection circuit, if the brightness is less than 20Lx, such as when the night room lighting is turned off, it is determined that it is not necessary to view the LCD 13, and the display is not performed. . That is, if the supply voltage from the solar cell 6 is a driving unnecessary value (for example, 0.7 V) or more, the third transistor Tr ₃ is turned on, and the first transistor Tr ₁ and the second transistor Tr ₂ are in the first state. However, if the supply voltage drops below the unnecessary driving value, the third transistor Tr ₃ is turned off, forcing the first transistor Tr ₁ and the second transistor Tr. The power supply from the backup battery 7 can be stopped by turning ₂ off. Since the water temperature detection and the water level detection are the same as those in the first embodiment, description thereof is omitted.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of a water level / water temperature detection circuit including a battery switching type power supply circuit according to a first embodiment.
2 is a circuit diagram of the system reset IC shown in FIG. 1. FIG.
3 is a front view of the LCD shown in FIG. 1. FIG.
4 is a graph showing a relationship between input and output of the system reset IC of FIG. 1; FIG.
5 is a graph showing a relationship between input and output of the liquid temperature detection latch circuit of FIG. 1; FIG.
6 is a graph showing the relationship between input and output of the water level detection latch circuit of FIG. 1; FIG.
FIG. 7 is a circuit diagram of a water level / water temperature detection circuit including a battery switching type power supply circuit according to a second embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Power supply circuit 2 Water temperature determination circuit 3 Oscillation circuit 5 Water level determination circuit 6 Solar battery 7 Backup battery 8 Thermistor 9 System reset IC
10a Water temperature detection latch circuit 10a, 10b First and second water detection latch circuit 11 Liquid container 13 LCD
16a Reference electrodes 16b, 16c First and second measurement electrodes

Claims (4)

A backup battery,
Solar cells,
Power replenishing means for supplying power from the backup battery by lowering the voltage value input from the solar battery lower than the minimum driving minimum required for driving other circuits;
A power supply stopping means for stopping the supply of power from the backup battery when the voltage value input from the solar battery falls below a driving unnecessary value lower than the minimum driving value ;
The power replenishing means maintains an off state if the voltage value input to the base from the solar cell is equal to or higher than the minimum driving value necessary for driving other circuits, and turns on if the voltage value is lower than the minimum driving value. A second transistor in a state,
Connecting the emitter of the second transistor to the base of the first transistor, connecting the emitter of the first transistor to the positive pole of the backup battery, and connecting the collector of the first transistor to the positive pole of the solar battery. Thus, if the second transistor maintains the off state, the first transistor also maintains the off state to supply power from the solar cell and stop supplying power from the backup battery, while the second transistor Is turned on, the first transistor is turned on to supply power from the backup battery in addition to the solar battery,
The power supply stopping means maintains an off state when a voltage value input to the base from the solar cell falls below a driving unnecessary value lower than the driving minimum value, and an on state if the driving value is equal to or higher than the driving minimum value. The third transistor is
If the third transistor is turned off by connecting the collector of the third transistor to the negative electrode of the solar battery and the backup battery and connecting the emitter to the collector of the second transistor, the second transistor and the first transistor A power supply circuit with a backup battery, wherein the power supply from the backup battery is forcibly turned off sequentially and stopped . A liquid container with a display function, which is driven by power supplied from the power supply circuit with a backup battery according to claim 1 and includes a water level display circuit for displaying a water level on a display unit based on a detection signal of a water level detection means. The water level display circuit includes: an oscillation circuit that outputs a pulse signal; a detection signal of the water level detection means is input to a set terminal; and a pulse signal of the oscillation circuit is input to a reset terminal, A liquid container with a display function, comprising a latch circuit for displaying a water level on the display. A display function comprising a temperature display circuit that is driven by the power supplied from the power supply circuit with a backup battery according to claim 1 and that displays the liquid temperature in the liquid container on the display unit based on the detection signal of the temperature detection means. The temperature display circuit includes an oscillation circuit that outputs a pulse signal, a system reset IC that determines a liquid temperature based on a detection signal of the temperature detection means, and an output signal from the system reset IC And a latch circuit that causes the display unit to display a temperature when a pulse signal from the oscillation circuit is input to a reset terminal. container. 4. The liquid container with a display function according to claim 2, wherein power supplied from the solar cell drive circuit to the water temperature determination circuit is supplied via a Zener diode connected in parallel.

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