JPH0134352B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a charging shortage warning device for an electronic device equipped with a solar cell.

The use of solar cells is attracting much attention as an energy supply source in various fields as well as energy saving. For example, in the field of watches, the commercial value of solar-powered watches has increased over the past few years due to their longer battery life and the elimination of battery replacement.

However, the solar cell watches currently on the market do not have enough area for the solar cells, as can be seen from the size of the watch body, so they are hardly charged in dark places. Additionally, watches are used in different ways depending on the user's living environment, and some people do not spend much time outdoors, so the solar cells receive little light and may become insufficiently charged. right.

FIG. 1 shows the charging function of the secondary battery.
AmAH is the initial capacity, BmAH is the residual capacity after discharge, and CmAH is the recovery capacity by charging after discharge. The depth of discharge is expressed as B/A x 100%, and the recovery efficiency is expressed as C/A x 100%. Therefore, by plotting the depth of discharge on the horizontal axis and the recovery efficiency on the vertical axis, the recovery efficiency at each depth of discharge of the secondary battery is shown. From the figure, it can be seen that the charging and discharging performance of the secondary battery at a deep depth of discharge deteriorates significantly compared to charging and discharging at a shallow depth of discharge.

In conventional solar cell-equipped electronic devices, users are unable to determine how much the battery capacity has decreased, and as a result, users intentionally leave the solar cell watch in the light even though the battery is insufficiently charged. Because the rechargeable battery is not exposed to water, the secondary battery is discharged more and more, and as mentioned above, the depth of discharge becomes deeper and the charging and discharging performance deteriorates significantly, which reduces the ability of the solar cell watch to have a long life due to charging. The drawback was that it was impossible to fulfill the mission.

In order to eliminate the above-mentioned drawbacks, the present invention provides an electronic device with a solar cell, which is equipped with a circuit that warns the user of insufficient charging if there is no operational output from the limiter for a certain period of time. It is something.

FIG. 2 is a circuit diagram of a conventional general solar cell watch, in which 1 is a solar cell and 2 is a secondary battery charged by the solar cell 1. In FIG. Reference numeral 3 denotes a watch body operating circuit which operates using the secondary battery 2 as a power source and drives the display body 4. 5 is a limiter circuit, which is a circuit that prevents overcharging of the secondary battery 2. A backflow prevention diode 6 prevents the current from flowing back from the secondary battery 2 when there is no output from the solar cell 1.

FIG. 3 shows an embodiment of a circuit diagram of an electronic device with a solar cell according to the present invention, and is particularly explained by taking a watch as an example. Note that the same components as in FIG. 2 are indicated by the same numbers to avoid duplication of explanation. 7
is an insufficient charge warning circuit that outputs a signal to the watch body operating circuit if there is no operating output from the limiter for a certain period of time. In other words, when the limiter operates, it means that the capacity of the secondary battery has recovered to 100%, and if there is no operating output from the limiter for a certain period of time, it means that the secondary battery has discharged to some extent. That's true.
For example, if the lifespan calculated from the initial capacity and current consumption of the secondary battery is 2 years, if there is no output from the limiter for 1 to 2 months, the insufficient charge warning circuit will operate. When the battery's depth of discharge reaches 5% to 10%, a warning circuit activates and prompts the user to charge the battery. Therefore, secondary batteries are used for charging and discharging at shallow depths of discharge, and thus the secondary battery It is possible to use the battery efficiently without deteriorating its charge/discharge performance.

FIG. 4 shows an embodiment of the insufficient charging warning circuit. 8 is the output from the monthly carry counter, 9 is the output from the limiter circuit, 10
is a flip-flop.

FIG. 5 shows an example of the operation of the insufficient charge warning circuit. If there is no output from the limiter 5 for one to two months, Q2 becomes Hi and outputs a charging insufficient warning signal to the watch body operation circuit 3.

On the other hand, when there is an output from the limiter circuit (when it is reset), Q2 becomes Lo and the insufficient charge warning signal is no longer output.

This insufficient charging warning signal makes it possible to prompt the user to charge the battery through a display on a liquid crystal display or a buzzer sound.

As described above in detail, the present invention can prompt the user to charge the secondary battery by providing a circuit that warns the user that the secondary battery is insufficiently charged when there is no operational output from the limiter for a certain period of time. Secondary batteries are repeatedly charged and discharged at shallow depths of discharge, making it possible to prevent deterioration in the charging performance of secondary batteries, which has a great effect on extending the lifespan of electronic devices equipped with solar cells. It brings about.

[Brief explanation of drawings]

Figures 1 (1) to (4) are diagrams showing the charging and discharging performance of secondary batteries. FIG. 2: A diagram showing an example of a circuit diagram of a conventional solar cell watch. FIG. 3: A diagram showing an embodiment of the circuit diagram of the solar cell watch of the present invention. FIG. 4: A diagram showing an embodiment of the charging shortage warning circuit of the present invention. FIG. 5: A diagram showing an example of the operation of the circuit of FIG. 4. 1...Solar cell, 2...Secondary battery, 3...Clock body operation circuit, 4...Display body, 5...Limiter,
6... Diode for backflow prevention, 7... Insufficient charge warning circuit, 8... Output from the monthly carry counter, 9... Operation output from the limiter, 10...
Flip flop.

Claims (1)

[Claims] 1. In a solar cell-equipped electronic device having a solar cell and a secondary battery charged by the solar cell,
A limiter that detects that the secondary battery is fully charged and outputs a signal, a counter that starts counting the elapsed time based on the signal from the limiter, and a warning of insufficient charging when the counter counts a predetermined time. 1. A solar cell electronic device, comprising: insufficient charge warning means for outputting a signal indicating that the secondary battery is over-discharged.