JPS5918842Y2 - Solar cell output adjustment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a solar cell output adjustment device for controlling the output of the solar cell to a constant level in a power supply device having a solar cell and a secondary battery charged therein.

Conventionally, power supplies used in electronic devices such as electronic watches have used a combination of secondary batteries and solar cells, and by irradiating the solar cells with light, the electrical energy converted by the solar cells is generated. is now used to charge secondary batteries or drive loads such as electronic devices.
When the above solar cell is irradiated with strong light such as direct sunlight, the converted electrical energy greatly exceeds the voltage of the secondary battery, and the electrical energy from the solar cell in this state is transferred to the secondary battery for a long time. If the secondary battery is supplied to There was a risk.

Therefore, conventionally, a constant voltage diode is connected in parallel to a secondary battery that uses the output of the solar cell as a charging power source, and when the output voltage of the solar cell reaches the operating voltage set by the constant voltage diode and the resistor, A system has been proposed that prevents overcharging current from flowing to the secondary battery by breaking down a constant voltage diode and bypassing the charging current.

However, in the conventional circuit system described above, a resistor connected in series with a voltage regulator diode is required to set the operating voltage of the bypass circuit that prevents overcharging current to the secondary battery. As the number of devices increases, the space required for their implementation also increases, which creates problems with the layout when mounting them on devices with limited space, such as electronic wristwatches, which hinders the miniaturization and thinning of watches, etc. I will do it.

In addition, when a voltage regulator diode breaks down, a considerable amount of bypass current flows, so if there are circuit elements that are airtight, densely packed, and easily affected by heat, such as a wristwatch, the voltage regulator diode Therefore, the capacity, size, and shape of the voltage regulating diode to be mounted are limited, and it may not be applicable to circuits that bypass large currents due to heat generation. there were.

The present invention was developed in view of the above points, and consists of connecting a regulator circuit whose conductivity changes depending on the illuminance of light to the output side of a solar cell that supplies electrical energy to a secondary battery, etc. By adjusting the amount of light using a light amount setting means such as an aperture hole or a filter, the electrical energy from the solar cell can be controlled to a value suitable for charging a secondary battery or driving a load, and
It is an object of the present invention to provide an output adjustment device for a solar cell, which allows a light amount setting means (light amount adjustment means) to be implemented in a wristwatch or the like in an advantageous manner in terms of space and cost.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the principle of the power supply device according to the present invention, in which a regulator circuit 2 whose conductivity changes depending on the illuminance of light is connected to the output side of a solar cell 1, and a regulator circuit 2 whose conductivity changes according to the illuminance of light. The light-receiving surface of the regulator circuit 2 is designed to receive the same light as the solar cell 1, and when the power generated by the solar cell 1 changes depending on the illuminance of the light, the conductivity of the regulator circuit 2 changes according to this change. At the same time, a part of the output from the solar cell 1 is sent to the regulator circuit 2.
control so that the power to the secondary battery 4 connected to the solar cell 1 via the backflow prevention circuit 3 and the load 5 such as an electronic circuit driven by the output of the secondary battery 4 is almost constant. be done.

FIG. 7 shows a specific example of the circuit configuration of the block diagram shown in FIG.
A plurality of CdS photoconductive cells are used in the regulator circuit 2, and the photoconductive cells 2 are connected in series and parallel to each other in order to obtain the predetermined voltage and current capacity required for the regulator circuit 2. and are connected in parallel to the solar cell 1.

Further, a diode is used in the backflow prevention circuit 3, and this diode 3 is connected between the photoconductive cell 2, the connection point of the resistor 6, and the positive electrode of the secondary battery 5.
It is connected to the negative electrode of the positive battery 1.

Further, a light amount controlling means 7 consisting of a light transmitting window is installed opposite to the photoconductive cell 2.

In the circuit with the above configuration, when the solar cell 1 is irradiated with light and the illuminance is increased by 2 times, 3 times, etc., the voltage-current characteristics of the solar cell are as shown in Figure 2. It has become.

In addition, when the solar cell 1 is sufficiently activated, the current I(L) generated by the solar cell 1 with respect to the illuminance of light is proportional to the illuminance, so ■(L) = KL (K: proportional constant).

When the solar cell 1 is connected to a photoconductive cell 2 whose resistance value changes depending on the load, that is, the illuminance (having the characteristic that the resistance value decreases as the illuminance increases), the photoconductive cell 2 The potential difference ■ (L) appearing at both ends is ■ (L no i (L)
- R(L) (R(L): resistance value of the photoconductive cell 2 depending on illuminance; j (L): current flowing through the photoconductive element 2 depending on illuminance).

Now, the illuminance of the light irradiating the solar cell 1 is shown in Figure 3.
2L, 3L, etc., in order to keep the potential difference (L) between both ends of the photoconductive cell 2 at a constant value E as shown by the broken line 10 in FIG. The resistance value R(L) of the photoconductive cell 2, which depends on the resistance, must satisfy R(L no E/i (L)).

In other words, as the illuminance increases, the photoconductive cell 2
By decreasing the resistance value R(L) so that (L) remains constant, the potential difference between both ends of the photoconductive cell 2 can be kept constant regardless of the intensity of illumination.

That is, by utilizing the fact that the conductivity of the photoconductive cell 2 changes depending on the intensity of light, out of the power generated by the solar cell 1, the electrical energy and secondary energy required to drive the electronic device (load) 5 are reduced. However, extra electrical energy is consumed in the photoconductive cell 2 other than the electrical energy required to adequately charge the battery.

Also, when (L) is kept equal and constant the voltage of the secondary battery 4, the charging current to the secondary battery is zero, and when the illuminance changes, V(L) is the voltage of the secondary battery. The change in resistance value R(L) with respect to illuminance to maintain it equal to
It becomes like curve 11 in the figure.

Here, the resistance value R(L) depending on the illuminance is the characteristic curve 1
When the illuminance-resistance characteristic shown by the straight line 12 is slightly larger than 1, 1, that is, when the conductivity of the photoconductive cell 2 with respect to the illuminance is made very low (when taken at a point higher than the voltage E shown in Fig. 2). ), the potential difference across the photoconductive cell (regulator circuit) 2 becomes larger than the terminal voltage of the secondary battery 4, and the accompanying charging current to the secondary battery 4 also increases as the voltage across the photoconductive cell increases. Since it is constant, it is kept at a small constant value regardless of the magnitude of illuminance.

However, in the regulator circuit 2 of the present invention, Cd
A CdS photoconductive cell is used, but when this CdS photoconductive cell is placed in the same illuminance atmosphere as the solar cell 1, its illuminance-resistance characteristic is approximately inversely proportional to the illuminance, as shown by the straight line 13 in Figure 3. Moreover, since the manufacturing error in the resistance value of the CdS photoconductive cell is ±50%, if this CdS photoconductive cell is simply placed in an atmosphere with the same illuminance as the solar cell 1, its illuminance-resistance characteristic 13 cannot match the characteristic 12 required for the device of the present invention.

Therefore, in accordance with the present invention, by reducing the amount of light illuminated on the CdS photoconductive cell 2, the relative difference between the illuminance of the light incident on the solar cell 1 and the illuminance of the light incident on the CdS photoconductive cell 2 is reduced. Then, the illuminance-resistance characteristic 13 of the CdS photoconductive cell 2 was made to match the characteristic 12.

Figures 4 and 5 show the solar cell 1 and the CdS photoconductive cell 2.
This shows an example of the light amount adjusting means of the present invention for creating a relative illuminance difference between the solar cell 1 and the CdS photoconductive cell 2 in a hand display type electronic watch having a built-in power supply device consisting of a secondary battery 4 and a case. The movement 21 installed inside the movement 20 has a crystal oscillator, a CMO5IC assembly, a drive mechanism for the hands (long, short, and second hands) 22, a secondary battery, etc., and the movement 21 has characters on the side of the hands 22. A plate 23 is attached, and a solar cell 1 and a CdS photoconductive cell 2 are attached to the movement 21 located directly below this dial plate 23, and this solar cell 1
Separate through holes 24 and 25 are formed in the dial 23 facing each light receiving surface of the CdS photoconductive cell 2.

Then, the opening area of the through hole 25 is limited so that the amount of light to the light-receiving surface of the CdS photoconductive cell 2 is smaller than the amount of light to the light-receiving surface of the solar cell.
The amount of light is adjusted by providing a difference in illumination between the S photoconductive cells 2 so that the illuminance-resistance characteristic of the CdS photoconductive cell 2 matches the characteristic 12 in FIG. 3.

Note that 27 is a cover glass attached to the case 20 so as to cover the dial 23 and the hands 22.

Therefore, when the light that has passed through the cover glass 27 is irradiated onto the dial 23, the light that has passed through the through hole 24 of the dial 23 will irradiate the solar cell 1 and generate an output according to the illuminance. The CdS photoconductive cell 2 whose light amount is adjusted by the through hole 25 automatically controls the output from the solar cell 1 to a constant value at a low rate suitable for charging the secondary battery 4 and driving the load 5.

FIG. 6 shows another embodiment of the light amount adjusting means of the present invention for creating a relative illuminance difference between the solar cell 1 and the CdS photoconductive cell 2 in a digital display type electronic watch. A module (CMO8IC) in which a conductive cell 2 and a liquid crystal display mechanism 30 are arranged on the cover glass 31 side
(including assembly, crystal oscillator, movement, etc.)3
2 is installed in the case 33, and the cover glass 31
By forming a coating layer 34 on the inner surface of the solar cell 1 and the CdS photoconductive cell 2, a light transmitting window 35, 36 is formed in a portion facing the light receiving surface of the solar cell 1 and the CdS photoconductive cell 2, and a light transmitting window 35, 36 is formed on the inner surface of the CdS photoconductive cell 2. A display window 37 is provided in each portion.

Then, the amount of light to the light receiving surface of the CdS photoconductive cell 2 is
The light amount is adjusted so that the illuminance-resistance characteristic of the CdS photoconductive cell 2 matches the characteristic 12 in FIG. 3 by limiting the opening area of the light transmission window 36 so that it is smaller than that of the solar cell.

Also in this embodiment, the amount of electricity supplied by the solar cell 1 to the secondary battery 4 etc. can be controlled to a constant value at a low rate, regardless of the illuminance of the incident light.

Note that in each of the above embodiments, the amount of light to the CdS photoconductive cell 2 is set by the opening area of the through hole 25 or the light transmission window 36, but the present invention is not limited to these; for example, The same method as in the above embodiment can also be achieved by attaching a filter to the light-receiving surface of the CdS photoconductive cell 2 to limit transmission of light.

Furthermore, the present invention is of course applicable not only to electronic watches but also to electronic desktop calculators that use solar cells and secondary batteries as power sources.

As described above, according to the device of the present invention, the amount of light incident on the regulator circuit connected to the output side of the solar cell is reduced.
Since the illuminance resistance characteristics of the regulator circuit can be changed by adjusting it with a light amount setting means such as a filter, the electrical energy supplied from the solar cell for charging the secondary battery etc. can be controlled to the optimum value. , there is no risk of the secondary battery being overcharged or the load becoming overvoltage, and it is possible to prevent performance degradation and damage due to overcharging of the secondary battery, and to improve the life of the secondary battery. This can contribute to the realization of electronic watches that do not require battery replacement.

In addition, in this invention, the means for adjusting the amount of light incident on the regulator circuit for controlling the output of the solar cell to a value suitable for charging the secondary battery and driving the load is provided with a device facing the photoconductive cell of the regulator circuit. By using the through-hole provided in the device, it is easy to install the light amount adjustment means in wristwatches, etc., and it is more advantageous in terms of space and cost than the conventional method using constant voltage diodes. There is no need to consider any thermal considerations during implementation, and when applied to a wristwatch, it has the effect of easily making it smaller and thinner.

In particular, when a light transmission window for adjusting the amount of light to the photoconductive cell is formed on the dial or coating layer, it is easy to implement the light amount adjustment means in the watch, and almost no space is required for installation in the watch. .

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the principle of the power supply device in this invention, Fig. 2 is a voltage-current characteristic diagram of a solar cell, Fig. 3 is an illuminance-resistance characteristic diagram of a photoconductive element in this invention, and Fig. 4 The figure is a plan view of a hand display type electronic timepiece to which this invented device is applied, FIG. 7 are specific circuit configuration diagrams of the block diagram in FIG. 2. 1...Solar cell, 2...Regulator circuit (CdS
photoconductive cell), 4... secondary battery, 5... load, 23
...Dial board, 25...Through hole, 27...Cover glass, 36...Light transmission window.

Claims (1)

[Scope of utility model registration request] A solar cell that supplies electrical energy to at least a secondary battery, and a photoconductive conductor that is connected in parallel to the solar cell and controls the output of the solar cell to a constant level by changing the conductivity according to the illuminance of the light. The cell is equipped with a regulator circuit and a light transmitting window for limiting the amount of light formed opposite to the light receiving part of the regulator circuit. 1. A solar cell output adjustment device, characterized in that it is suitable for charging secondary batteries, etc.