JPH02144886A - Solar cell type power supply circuit and illumination fixture - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention uses solar cells and secondary batteries as power sources and can be used in various devices such as garden lights, gate lights, foot lights, pumps, and marker lights. Regarding battery-powered power supply circuits.

2. Description of the Related Art In a power source that charges a secondary battery using a solar cell, an overdischarge prevention circuit is used to prevent performance deterioration of the secondary battery. In addition, a circuit that monitors and switches the output of solar cells is also used for a daylight switch that automatically turns on the lighting device only at night.

Problems to be Solved by the Invention However, these conventional circuits use dedicated ICs and use logic circuits to judge the monitored power supply voltage and optical sensor output, resulting in complex circuits and a large number of components. It was something.

Therefore, there is a drawback that the IC cost and circuit assembly cost are high.

In addition, there is a second drawback that the transistor in the output section is easily damaged due to circuit failure or load overload during long-term outdoor use. Devices using solar cells are often used for a very long time in a nearly maintenance-free state, and cost requirements are also very strict.

The present invention solves the above-mentioned conventional drawbacks in cost and reliability, and provides a low-cost, highly reliable power supply circuit with over-discharge prevention and daylight switch functions that is ideal for solar cell application equipment, and utilizes the same. The purpose of this project is to provide lighting equipment with a

Means for Solving the Problems The present invention provides a bipolar switch with low on-resistance for a switch at the output section of a DC power supply in which the positive electrode and the positive electrode and the negative electrode and the negative electrode of a solar cell and a secondary battery are connected through one backflow prevention diode. A type transistor is used, and a junction type transistor whose base has an inversion function and whose current saturates is connected to the source or drain of a field effect transistor (FIT). and F
If the IT is P-channel, connect the drain and base, and connect a constant voltage diode between the positive power supply and the source; if it is N-channel, connect the source and base, and connect the constant voltage diode between the source and the negative power supply. Connect the voltage diode. Further, in the case of a P channel, the positive side of the solar cell is connected to the gate, and in the case of an N channel, the negative side of the solar cell is connected to the gate. Therefore, the output end of the solar cell connected to the backflow prevention diode is always connected to the gate.

At least one light emitting diode (LICD) is used instead of the Zener diode normally used as a constant voltage diode.
When used individually, the rise characteristics can be made steeper. In addition, even if the load of a lamp etc. is cut off, the FI of 0.6 to 3 mm
The LICD is made to light up with the drain current of T.

Effect The effect will be described below in the case of using the FIT of the P channel. The operating voltage of solar cells decreases at night, causing FIT
When the gate potential of drops below about 1V with respect to the source,
The FICT is switched on, and a current several meters below the current flows from the power supply through the constant voltage diode and the FICT to the base of the bipolar transistor. Therefore, a load current of several hundred mA or more can flow depending on the load impedance. When the voltage of the secondary battery becomes lower than the set voltage of the constant voltage diode due to current consumption, the drain current of the FET suddenly decreases, and the base current of the transistor also decreases rapidly, and the load current is cut off regardless of the gate potential, regardless of day or night. Prevents over-discharge of secondary batteries. At this time, the current flowing through the FICT is small and can be ignored. Since the switch here is an analog switch, no chattering occurs due to potential recovery of the secondary battery when the switch is turned on. In addition, if a bypass resistor is connected between the drain and base and the ground, the base current can be adjusted even if the drain current is constant at the same illumination intensity and the same power supply voltage, so the setting of the illuminance at which the switch is turned on can be changed. It is also possible to adjust the emission intensity of the LED used as a constant voltage diode when the load is cut off.

Even if N-channel FICT is used, the operation is the same, only the connection is different.

Embodiment Among the embodiments according to the present invention, an embodiment of a solar cell type power supply circuit using a P-channel FIT is shown in FIG. 1, and the measurement results of its current-voltage characteristics are shown in FIGS. 2 and 3. .

In FIG. 1, the positive electrode of a solar cell 1 is connected to a Ni-C
Secondary battery 3 with a rated voltage of 6V, such as a battery or lead-acid battery
A charging circuit was constructed by connecting the positive terminal to the positive terminal of the terminal, and connecting the negative terminal in common as the ground terminal. As a monitor of the power supply voltage from the positive electrode of the secondary battery, three red LEDs with a steep rise are connected.
The solar cell 1 was connected to the source of a P-channel junction type FICT via a constant voltage diode 6 connected in series, and the positive electrode of the solar cell 1 was connected to the gate of the FICT. Also, the output side is 0.5
A general-purpose bipolar transistor 6 was connected in series to the negative electrode side of the W lamp 7, and the drain of the FiCT was connected to its base. Further, a resistor 8 of 10Ω to 200Ω was connected between the base and the emitter, which is a ground terminal. Junction type F
In IT, the absolute value of the gate potential with respect to the source is 1v to 1.
Since it has an inversion function that switches off when the voltage exceeds 6V and switches on when the absolute value of the gate potential is near Ov, you can simply connect the operating voltage of the solar cell to the gate of the FICT by properly combining it with a solar cell. in,
Indicates a switch function that is switched on only at night. In the case of a single crystal solar cell, the gate potential during nighttime use is 0.
ranges from 1 to 1v, and gate potentials o, 1v and 1v
Figure 2 shows the measurement results of the load current and power supply voltage at the time of . The load current that the lamp lights up at a voltage of 5.6 to 6.7 V is approximately 80 V in proportion to the steep rise of the constant voltage diode using the LED! IIA flows, and at voltages higher than that, the increase in current is suppressed reflecting the current saturation characteristics of the FIT. In the case of a secondary battery with a rated voltage of 6V, the usage range is approximately 5.5V to 6.8V, so when the power supply voltage changes, the load current will be 80mA to 95m, and as the voltage decreases, the lamp lighting range will change. The effect of suppressing current consumption was also good.

Figure 3 shows the measurement results of the load current against the gate potential.As the voltage of the secondary battery decreases within the operating range, the gate potential at which the switch is turned on, that is, the illuminance, decreases, and the lighting time and load current automatically change within the lighting range. has been reduced. Furthermore, compared to N-channel, P-channel junction FIT is
The temperature change in the gate potential at which the switch is turned on was very small, making it ideal for implementing the present invention. FIG. 4 is a perspective view of an embodiment of the solar-powered lighting device according to the invention, and FIG. 6 is a plan view of the same from below. A solar cell 1 made into a module with a glass window material is fitted into an aluminum or plastic casing 1o in which the circuit part, the secondary battery and the base part of the lamp shown in Fig. 1 are housed, and a waterproof rubber is sandwiched between them.
Cover 9 was fixed with presser bolts. A shade 11 having a window made of glass or transparent plastic is fixed to a casing 1o with screws, and a post 12 is inserted into a hole in a support part of the casing 10 to fix it, and the shade 11 is fixed while being lifted from the ground or floor. If the LKDl 3 used as a constant voltage diode is exposed to the outside of the housing 10 inside the shade 11 together with the lamp 7, and the power supply voltage is 4V or more, even if the miniature bulb goes out or burns out at a voltage of 6.6V or less. LKDl 3 was able to light up at night to indicate its location. In addition, since the solar cell 1 is integrated with the housing 10, it is easy to construct a groove, and since the solar cell is placed horizontally, there is no need to adjust the installation location or angle, and objects cannot be placed on top of the solar cell. It could be easily turned on even in the daytime by simply emitting light in one part, and there was no need to use an unreliable contact switch.

Effects of the Invention According to the present invention, it is possible to achieve low cost, high reliability, and save power consumption with a simple analog element groove bottom.

A solar power supply circuit with daylight switch function and overdischarge prevention function was obtained. Furthermore, even when the load lamp goes out, the LED indicates the location, and the solar cell also serves as a switch, making it possible to obtain a low-cost and highly reliable solar-powered lighting fixture.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a solar cell type power supply circuit using a P-channel FIT according to an embodiment of the present invention, and FIGS. 2 and 3 show current and voltage measurement results of the embodiment of FIG. 1. FIG. 4 is a perspective view of an embodiment of the solar cell type lighting device according to the present invention, and FIG. 6 is a plan view of the embodiment of FIG. 4 viewed from below. 1... Solar cell, 2... Backflow prevention diode, 3... Secondary battery, 4... FK
T, 5... Constant voltage diode, 6... Transistor 7... Lamp 8......
resistance. Name of agent: Patent attorney Shigetaka Awano and 1 other person1-
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Claims (3)

[Claims] (1) In a DC power supply in which a solar cell for charging power is connected to a secondary battery via a backflow prevention diode, a constant voltage diode is connected to the source or drain of a junction field effect transistor, and the constant voltage diode is not connected. By connecting the base of the bipolar transistor to the drain or source, and connecting the output terminal of the solar cell connected to the reverse current prevention diode to the gate of the field effect transistor, the overdischarge prevention switch of the secondary battery and the low A solar battery power supply circuit characterized by an automatic switch-on function based on illuminance. (2) It has a solar battery type power supply circuit according to claim 1, and together with a lamp connected to the output end of the power supply circuit, light from at least one light emitting diode used as a constant voltage diode is emitted from the outside. A solar-powered lighting device characterized by being arranged so that it can be seen more clearly. (3) A solar cell type lighting device according to claim 2, characterized in that a solar cell is arranged horizontally on the upper surface of a lamp housing.