JPS6027922A - Electronic equipment - Google Patents

Abstract

PURPOSE:To prevent an unnecessary leakage of current in a backup capacitor by charging the capacitor only when a battery is replaced while the capacitor is not charged in an in-use state. CONSTITUTION:When a battery cover DK is slid as shown by an arrow A, a switch S interlocked with the cover DK moves to turn on, and the capacitor C starts being charged by the battery B. While the battery B is replaced by opening the cover K, the capacitor C is charged sufficiently, and a memory M is backed up with charges accumulated in the capacitor C at the moment the battery B is detached; when a new battery B is installed and the cover DK is closed, the switch S turns off again and the capacitor C is disconnected electrically from the battery B. Therefore, the capacitor C is connected to the battery B electrically only when the cover DK is opened, so no unnecessary leak current flows in the normal in-use state and the life of the battery is prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field) The present invention relates to an electronic device equipped with a backup capacitor for a volatile memory, and particularly relates to charging control of the capacitor.

(Conventional) As shown in Figure 1, in the conventional method of this type, battery B is connected to a volatile memory M whose stored data disappears when the power is cut off, and the battery B is connected in parallel to the battery B. When battery B is removed for a short period of time to replace battery B, the charge stored in capacitor C is supplied to memory M, and the data in memory M is erased. It was preventing this. In this conventional system, the capacitor C was constantly charged compared to the battery B, and the leakage current of the capacitor CI:D was constantly flowing, accelerating the battery B's consumption.

The present invention was made in view of this point, and the backup capacitor is not charged during normal use, but the capacitor is charged only when the battery is replaced. The purpose of this is to prevent unnecessary leakage current from the capacitor under certain conditions.

(Example) An example of the present invention will be described below with reference to the drawings. Figure 2 shows an example of a JJ with the battery cover DK closed, 1
1, the switch S is OFF, and no current flows from the battery B to the capacitor C. battery cover dk
When the switch S is slid in the direction of the arrow A, the switch S linked to the battery cover DK moves down and turns ON, and charging of the capacitor C from the battery B starts. This battery cover DK
While opening the battery and replacing battery B, capacitor C will be sufficiently charged, and when battery B is removed, the charge stored in capacitor C will be able to back up memory M, and when a new battery B is inserted, the battery When the cover DK is closed, the switch date becomes 10FF again, and the capacitor C is electrically disconnected from the battery B. In other words, capacitor C is electrically connected to battery B only when battery cover DK is opened, so no unnecessary leakage current flows during normal use, reducing the load on the battery and extending battery life. I can do things.

FIG. 3 is an overview diagram of the electronic device equipped with the circuit shown in FIG. 2. By sliding the battery cover DK in the direction of arrow A, the battery housed inside can be replaced. T is a stopper to facilitate the operation of the battery cover DK. H is the main body, DIF is the display, and KB is the keyboard.

(Effects) As explained above, according to the present invention, 171) leakage current can be prevented with a simple configuration without requiring any special effort on the part of the operator. If necessary, it is also possible to connect a resistor R in series with the capacitor C as shown in FIG. 4 to limit the charging current to the capacitor C and reduce the voltage drop at the initial stage of charging the battery B.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a conventional example, Fig. 2 is a block diagram of an embodiment of the present invention, Fig. 3 is an external perspective view of an electronic device showing an embodiment of the present invention, and Fig. 4 is a current limiter. FIG. 2 is a diagram showing an example of a circuit. M...Memory C...Capacitor B...Battery DK...Battery cover S...Switch applicant Canon Corporation

Claims (2)

[Claims] (1) In an electronic device that has a volatile memory whose stored data disappears when the power is cut off, and a battery and a capacitor that retain the data in the memory, a 146-meter battery compartment for storing the battery is provided. means for detecting whether the battery cover is opened or closed;
An electronic device characterized by having a control circuit for executing. (2) The electronic device according to item 1 above, characterized in that a resistor is connected in series to the capacitor.