JPH0450549B2 - - Google Patents

Description

Detailed Description of the Invention The present invention provides discharge control of a high-capacity capacitor during power backup of a long-life electric clock that has a solar cell and stores the output current of the solar cell in a high-capacity capacitor to maintain the movement of the clock. Regarding.

A conventional discharging circuit (charging circuit omitted) is shown in FIG. In Fig. 1, 1 is a clock load, A is a parallel connection with a secondary battery 2, B is a connection via an electric double layer capacitor 3 and a discharge diode 4, and C is a connection via a switch element 5. . In c.
6 is a flip-flop, and 7 is the output from the month carry counter. Solar cell output 8 is 1~
If it is not present for two months, the switch element 5 is turned off.
In any case, in A, the discharge cannot be controlled, in B, there is a loss due to a drop in the forward voltage of the diode 4, and in C, the discharge is stopped and wasteful if the output voltage from the solar cell does not reach the set value for a certain period of time. Although this is a circuit that prevents voltage drops, it predicts the discharge voltage over time based on the discharge characteristics of the secondary battery, and does not detect the true terminal voltage, but due to variations in the characteristics of the secondary battery. It becomes difficult to set a strict discharge stop voltage. Particularly when an electric double layer capacitor, which has a lower capacity than a secondary battery, is provided as a secondary power source, wasteful discharge after the clock has stopped significantly delays the charging time when restarting the clock.

The present invention has been made to eliminate such drawbacks, and aims to improve the duration of the watch during back-up in a solar powered wristwatch equipped with a high-capacity capacitor, and to prevent as much as possible the drop in discharge voltage when the watch is not operating. It is said that

The present invention will be described in detail below based on Examples. FIG. 2 shows an embodiment of a discharge circuit (solar cell and charging circuit omitted) according to the present invention, in which a watch load 1 is connected to an electric double layer capacitor 3 via a switch element 5.
It is connected to the. 9 is a solar cell electromotive voltage detection circuit, and its output 12 is output when the electromotive voltage is below a reference value. 10 is a terminal voltage detection circuit of the electric double layer capacitor 3, and its output 11 is output when the terminal voltage is higher than a reference value. 1
3 is an AND gate which turns on the switch element 5 when both inputs 11 and 12 have signals. The reference voltages at 9 and 10 are set to the minimum operating voltage of the clock load 1, and if the capacitor 3 is charged above the minimum operating voltage, it will naturally back up, but if it is discharged below the minimum operating voltage, the clock will Discharging to load 1 is prohibited. In other words, the loss in the non-operating voltage range of the watch is mainly due to the self-discharge of the capacitor.

As seen in the above example, the watch is equipped with a detection circuit for the electromotive voltage of the solar cell and a detection circuit for the terminal voltage of the high-capacity capacitor, and the discharge circuit is opened and closed depending on the level of the detected voltage. This prevents wasteful current loss during operation and shortens the charging time, making it possible to provide the optimal product as a solar battery wristwatch. Furthermore, it is of great significance to expand the scope of application from secondary batteries to highly reliable electric double layer capacitors as a backup for solar cells.

[Brief explanation of drawings]

A, B, and C in Figure 1 are discharge circuit diagrams of a conventional solar powered wristwatch. FIG. 2 is a discharge circuit diagram of the solar battery wristwatch according to the present invention. 1...Clock load, 2...Secondary battery, 3...Electric double layer capacitor, 4...Diode, 5...Switch element, 6...Flip-flop, 7...Month carry signal, 8...Solar cell Output signal, 9...
Solar battery electromotive voltage detection circuit, 10... Capacitor terminal voltage detection circuit, 11... Output signal from the capacitor terminal voltage detection circuit, 12... Output signal from the solar battery electromotive voltage detection circuit, 13... AND gate.

Claims (1)

[Scope of Claims] 1. A solar cell watch comprising a watch load, a solar cell serving as a power source for the watch load, a high-capacity capacitor for storing an output current of the solar cell, and a means for charging the high-capacity capacitor, The switch element connects the clock load and the high-capacity capacitor, a means for detecting the electromotive voltage of the solar cell, and a means for detecting the terminal voltage of the high-capacity capacitor, and the switch element detects the detected voltage of the high-capacity capacitor. is above the set voltage and the detected voltage of the solar cell is below the set voltage, the switch element is turned on and opens or closes in response to the level of the detected voltage of the solar cell and the high capacity capacitor. A solar cell watch characterized by: 2. The solar cell watch according to claim 1, characterized in that an electric double layer capacitor is used as the high-capacity capacitor.