JPH1063351A - Power unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power unit where supply of power from a battery is effectively utilized. SOLUTION: Since the voltage of an AC adapter 2 is higher than that of the battery 1 because of the charging of the battery 1 by using the AC adapter 2, the AC adapter 2 is connected so as to open a contact rla, the battery 1 is connected so as to prevent the back flow of current from the AC adapter 2 to the battery 1 by a first diode D1, current is permitted to flow from the AC adapter 2 by way of the second diode D2, the voltage obtained by subtracting forward direction voltage for the portion of lowering V2 by the second diode D2 from the voltage of the AC adapter 2 is inputted to a DC/DC converter 4 and the DC/DC converter 5 converts it into a prescribed voltage so as to supply a power source.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply for information processing equipment such as a personal computer and a printer, and more particularly to a power supply provided with a diode OR circuit for connecting an AC adapter and a battery.

[0002]

2. Description of the Related Art A conventional power supply device such as a personal computer or a printer using an AC adapter and a battery uses an AC adapter 2 and a battery 1 at the same time, as shown in FIG.
And a connection circuit 103 for connecting each of them.
C adapter 2 and battery 1 are connected to diodes D2 and D, respectively.
Although a diode OR circuit connected by 1 is widely used, in recent years, a connection circuit using a MOS field effect transistor instead of the diodes D2 and D1 has also been adopted.

As shown in FIG. 2, the operation of this conventional power supply device is performed when only the AC adapter 2 is connected and used.
When a current flows through the diode D2 and only the battery 1 is connected and used, a current flows through the diode D1 and when the AC adapter 2 and the battery 1 are connected and used, the AC adapter 2 or the battery 1 is connected. Since the current flows from the higher voltage side, the voltage of the AC adapter 2 is generally higher than the voltage of the battery 1, so that the diode D
2 and the diode D1 prevent the current of the AC adapter 2 from flowing to the battery 1 or the current of the battery 1 from flowing to the AC adapter 2.

On the other hand, in general, the voltage of the AC adapter 2 and the voltage of the battery 1 are different, and the voltage of the battery 1 decreases due to the connection of the load, so that the voltage output from the connection circuit 103 also varies. The voltage output from the circuit 103 is stabilized by the DC / DC converter 4.

[0005]

As described above, the conventional power supply uses the diode OR circuit to connect the AC adapter 2 and the battery 1. Therefore, when the battery 1 is used, the diode D1 is used. And the forward voltage drop V
There was a problem that a one-minute loss occurred and the power supplied from the battery could not be used effectively.

[0006] Therefore, an object of the present invention is to provide a power supply device that can effectively use power supplied from a battery.

[0007]

In order to solve the above-mentioned problems, a power supply device according to the present invention comprises a battery, an AC adapter for generating a DC power supply from an input AC power supply, and an AC adapter.
D driven by C adapter or battery
A C / DC converter, a first diode for supplying the output power of the battery to the DC / DC converter, a switch connected in parallel to the first diode,
When detecting the connection of only the battery and the second diode for supplying the DC power generated by the C adapter to the DC / DC converter, controlling to turn on the switch to short-circuit the first diode, A connection circuit comprising: a control circuit that controls to turn off the switch and open the first diode when connection of only the AC adapter is detected / connection of the AC adapter and the battery is detected. And

[0008]

Next, a power supply device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a power supply device according to an embodiment of the present invention.

A power supply according to an embodiment of the present invention comprises:
As shown in FIG. 1, a battery 1, an AC adapter 2 for generating a DC power supply from an input AC power supply, and a DC / DC drive driven by the AC adapter 2 or the battery 1.
A DC converter 4, a first diode D1 for supplying output power of the battery 1 to the DC / DC converter 4,
The switch RL connected in parallel to the first diode D1
And DC / DC power generated by the AC adapter 2
When the connection of only the second diode D2 supplied to the converter 4 and the battery 1 is detected, the switch RL is turned on to control the first diode D1 to be short-circuited. And a control circuit 31 for controlling to turn off the switch RL and open the first diode D1 when detecting the connection of the first connection.

Next, the operation of the power supply according to one embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, when the power supply device according to the embodiment of the present invention is operated using only the AC adapter 2, the control means 31 detects the connection of the AC adapter 2 and RL coil rlb does not work,
With the contact rla kept open, a current flows from the AC adapter 2 via the second diode D2, and a forward voltage drop V from the voltage of the AC adapter 2 due to the second diode D2.
2 is input to the DC / DC converter 4, and the DC / DC converter 4 converts the voltage into a predetermined voltage to supply power.

When the operation is performed using only the battery 1, the control means 31 detects the connection of the battery 1 and the coil rlb of the switch RL is operated, so that the short-circuited contact r
A current flows through la, and the voltage of the battery 1 is input to the DC / DC converter 4 without passing through the first diode D1. The DC / DC converter 4 converts the voltage into a predetermined voltage to supply power.

Further, when the battery is operated using the AC adapter 2 and the battery 1, the voltage of the AC adapter 2 is generally higher than the voltage of the battery 1 because the battery 1 is charged by using the AC adapter 2. , The AC adapter 2 is connected to open the contact rla, the battery 1 is connected, and the first diode D1 prevents current from flowing back from the AC adapter 2 to the battery 1.
A current flows from the adapter 2 via the second diode D2, and a voltage obtained by subtracting the forward voltage drop V2 due to the second diode D2 from the voltage of the AC adapter 2 is DC / DC.
The power is supplied to the converter 4 and converted to a predetermined voltage by the DC / DC converter 5 to supply power.

[0015]

As described above, according to the power supply device of the present invention, when a battery is used, the forward voltage drop of the diode in the connection circuit composed of the diode OR circuit to which the AC adapter and the battery are connected. As a result, there is an effect that the power supplied from the battery can be effectively used.

[Brief description of the drawings]

FIG. 1 is a block diagram of a power supply device according to an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional power supply device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery 2 AC adapter 3 Connection circuit 4 DC / DC converter 31 Control means D1 1st diode D2 2nd diode RL switch rla switch (contact) rlb switch (coil)

Claims (1)

[Claims] 1. A battery, an AC adapter for generating a DC power supply from an input AC power supply, a DC / DC converter driven by the AC adapter or the battery, and an output power supply of the battery to the DC / DC converter , A switch connected in parallel to the first diode, a second diode supplying DC power generated by the AC adapter to the DC / DC converter, and detecting connection of only the battery. When you do
The switch is turned on to control the first diode to be short-circuited, and when connection of only the AC adapter / connection of the AC adapter and the battery is detected, the switch is turned off to open the first diode. And a connection circuit having control means for controlling the power supply.