JPH0435934Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an improvement of a power supply circuit that uses a solar cell as a power source and operates the electronic circuit only when the electromotive force of the solar cell reaches a value sufficient for the operation of the electronic circuit. In particular, it detects when the electromotive force of a solar cell exceeds a certain value by a part of the solar cell, and operates the connected electronic circuit only when the electromotive force of the solar cell exceeds a certain value. This is intended to prevent malfunctions. A further characteristic is that the electromotive force is detected by focusing on the characteristics of the solar cell and detecting the electromotive force of the entire solar cell by applying a load to a part of it and detecting the electromotive force of the entire solar cell. This means that the power is determined, and that there is no need to waste power.

Solar cells, which do not require periodic battery replacement, have been used as a power source for electronic devices, but if the solar cells are not irradiated with sufficient light, their electromotive force decreases, causing the connection to be interrupted. It is well known that when electronic circuits are operated, the initial clear (temporary reset) signal has the disadvantage of being incomplete and prone to malfunction. FIG. 1a shows a conventional example. In the figure, a plurality of power supply solar cells 2 are connected to an electronic circuit 10 via a current limiting resistor 4, and a Zener diode 6 for overcurrent prevention and a smoothing capacitor 8 are further connected in parallel. There is. Therefore, if sufficient light is not irradiated to the power supply solar cell 2 and an electromotive force higher than the minimum operating voltage of the electronic circuit 10 is not generated in the power supply solar cell 2, even if it operates, it will be in an unstable state and normal operation will not occur. There is a possibility that it will not be carried out.

FIG. 1b shows an external switch 1 for supplying a clear signal to solve the problem of FIG. 1a.
This is a circuit with 2. In other words, if the electronic circuit 10 is not operating normally when the electromotive force of the solar cell goes from below the minimum operating voltage to above the minimum operating voltage, the external switch 12 is pressed to input an auto-clear signal and normalize. It is making a movement. However, it was extremely troublesome to operate the switch each time to restore normal operation.

For this reason, electronic devices that use solar cells as a power source have been used only for devices that are always exposed to sufficient light during use, such as calculators.

However, in recent years, attempts have been made to expand the scope of use of solar cells without being limited by the environment or time in which they are used. It was proposed to be used for toys and accessories that only operate when the above conditions are met. In this case, it was necessary to solve the above-mentioned problem that if the electromotive force of the solar cell becomes lower than the minimum operating voltage, the clear signal that should be supplied may not be supplied.

The present invention solves the above-mentioned conventional problems, and its purpose is to prevent malfunctions when the electromotive force of the solar cell is less than the minimum operating voltage in an electronic circuit using a solar cell as a power source.

In order to achieve the above object, the present invention detects that the electromotive force due to the light irradiated to the solar cell by a part of the solar cell has exceeded a certain value, the electronic It is characterized in that it has an operating circuit that operates the circuit, and operates the connected electronic circuit only when the amount of light irradiated to the solar cell is sufficient to operate the electronic circuit normally.

Embodiments of the present invention will be described below based on the drawings. FIG. 2 is a circuit diagram showing a first embodiment of the present invention. Components having the same configuration as those in FIG. 1 are given the same numbers and the description thereof will be omitted.

In the figure, a plurality of power supply solar cells 2 are lined up, and a detection solar cell 14 for detecting the amount of light irradiated to the power supply solar cell 2 has the same shape and the same shape as the power supply solar cell 2. placed in place. In this embodiment, the detection solar cell 14 serving as the light detection means is of lower efficiency than the power source solar cell 2.

On the other hand, an operation circuit 16 that turns on or off the operation of the electronic circuit 10 according to a signal from a photodetector includes a three-terminal variable resistor 18, fixed resistors 20, 22, and 2.
4, transistors 26 and 28, and a Zener diode 30.

One end of the aforementioned detection solar cell 14 is directly connected to the common line, and the other end is connected to the common line via the variable resistor 18. The sliding terminal of the variable resistor 18 is connected to the base terminal of the transistor 26. The emitter terminal of the transistor 26 is connected to the cathode of a Zener diode 30, and the anode of the Zener diode 30 is connected to a common line. Also, the emitter terminal of the transistor 26 is connected to the resistor 20
It is connected to one end of the solar cell 2 for power supply via.
And the collector terminal of transistor 26 is resistor 2
It is also connected to one end of the solar cell 2 for power supply via 2. Further, the collector terminal of the transistor 26 is connected to the base terminal of the transistor 28 via the resistor 24. The collector terminal of this transistor 28 is connected to one end of the electronic circuit 10, and the emitter terminal is connected to one end of the power supply solar cell 2.
The other end of the power supply solar cell 2 is connected to a common line.

The operation of this circuit will be explained below.

When the electromotive force generated in the power supply solar cell 2 exceeds the minimum operating voltage of the electronic circuit 10, the variable resistor 18
The position of the sliding terminal of the variable resistor 18 is adjusted in advance so that the voltage applied between the base and emitter of the transistor 26 by the electromotive force of the detection solar cell 14 divided by the voltage exceeds the threshold voltage. put.

In this case, when the electromotive force generated in the power supply solar cell 2 is below the minimum operating voltage of the electronic circuit 10,
Transistor 26 is in an off state, and accordingly transistor 28 is also turned off. Therefore, the electronic circuit 10 does not operate.

However, when the electromotive force generated in the power supply solar cell 2 exceeds the minimum operating voltage of the electronic circuit 10, the transistor 26 turns on, and the transistor 26 is connected from the emitter to the base of the transistor 28 via the resistor 24.
Since current flows to the collector side of transistor 6, transistor 28 is turned on. As a result, the electronic circuit 10 operates normally due to the electromotive force generated by the solar cell 2.

As described above, according to this embodiment, the electronic circuit 10 is activated only when the electromotive force generated in the power supply solar cell 2 exceeds the voltage value at which the electronic circuit 10 can operate normally. Therefore, when used in accessories or toys that operate when the electromotive force of the solar cell reaches a sufficient value, malfunctions will not occur. Furthermore, in this embodiment, since a low-efficiency solar cell is used as the detection solar cell 14, which is a detection means for detecting the intensity of sunlight, the electromotive force generated in the power supply solar cell 2 is more reliably reduced. It is possible to detect that the voltage has exceeded the minimum operating voltage. The Zener diode 30 is provided to form a constant voltage circuit, but since the Zener diode 6 forms the constant voltage circuit, it may be omitted.

FIG. 3 is a circuit diagram showing another embodiment of the present invention. In FIG. 3, components having the same configuration as those in FIG. 2 are given the same numbers and their explanations will be omitted.

In FIG. 3, the operating circuit 32 includes a variable resistor 3
4, a resistor 36, and a transistor 38.

The variable resistor 3 is connected to both ends of the detection solar cell 14.
4 is connected, and the sliding terminal of the variable resistor 34 is connected to the base terminal of a transistor 38. The collector of the transistor 38 is connected to the resistor 38 and the operation signal input terminal of the electronic circuit 40.

The operation of this circuit will be explained below.

Similarly to FIG. 2, when the voltage generated in the power supply solar cell 2 exceeds the minimum operating voltage of the electronic circuit 10,
The position of the sliding terminal of the variable resistor 34 is adjusted in advance so that the voltage applied between the base and emitter of the transistor 38 exceeds the threshold voltage.

In this way, the electromotive force generated in the power supply solar cell 2 is
If the voltage is lower than the minimum operating voltage of the electronic circuit 10, the transistor 38 is turned off and the voltage is lowered from the collector to the electronic circuit 4.
No operation start signal is input to the operation start signal line connected to 0. Therefore, the electronic circuit 40 does not operate.

However, when the electromotive force generated in the power supply solar cell 2 exceeds the minimum operating voltage of the electronic circuit 40, the transistor 38 is turned on and a falling operation start signal is input to the electronic circuit 40. This causes the electronic circuit 40 to operate.

According to this embodiment, as in FIG. 2, when the electromotive force generated in the power supply solar cell 2 exceeds the minimum operating voltage for the electronic circuit 40 to operate normally, the electronic circuit 40 is activated. When used in accessories or toys that operate only when the electromotive force of the solar cell reaches a sufficient value, malfunctions will not occur.

As described above, according to the present invention, since the electromotive force of the solar cells is detected by some of the solar cells,
In addition to preventing wasteful power consumption, we have made it possible to judge the electromotive force with a margin for the load, so the electronic circuit is turned on only when the electromotive force generated in the solar cell exceeds a certain value. By doing so, when used in electronic devices that operate only when the electromotive force of the solar cell reaches a sufficient value, such as accessories or toys, malfunctions such as auto-clear not being activated can be prevented.

[Brief explanation of the drawing]

FIGS. 1a and 1b are circuit diagrams showing a conventional example. FIG. 2 is a circuit diagram showing an embodiment of the present invention. FIG. 3 is a circuit diagram showing another embodiment of the present invention. 2... Solar cell for power supply, 10... Electronic circuit, 1
4...Detection solar cell, 16...Operation circuit, 32
...Operation circuit, 40...Electronic circuit.

Claims (1)

[Claims for Utility Model Registration] (1) In a power supply circuit using a solar cell as a power source, a solar cell for detecting electromotive force is provided, and when the electromotive force exceeds a certain value, it is detected that the power supply circuit uses a solar cell as a power source. It has an operating circuit that supplies power to the connected electronic circuit to operate it, and when it becomes possible to generate sufficient electromotive force to operate the electronic circuit normally by the light irradiated to the solar cell. A power supply circuit using a solar cell, which operates the electronic circuit. (2) The detection solar cell that detects when the electromotive force of the solar cell exceeds a certain value as stated in claim 1 of the utility model registration claim is characterized by a lower efficiency than other solar cells. Power supply circuit using solar cells.