JPH06335236A - Power supply circuit - Google Patents

Abstract

PURPOSE:To eliminate the need for a diode for rectification and a capacitor for smoothing inside an AC adapter, at the same time, eliminate the need for a special circuit protective element even in the internal circuit of an electronic equipment, and further drive the electronic apparatus with a commercial AC power supply regardless of the polarity of the AC adapter to be connected by providing a rectifier circuit in a power supply circuit. CONSTITUTION:In this power supply circuit of an electronic apparatus where a battery 4 and a commercial AC power supply are switched, a diode 6 is provided on a circuit connecting the cathode of the battery 4 and a cathode terminal c of a DC input jack 2 is provided, the diode 6 protects a circuit when connecting an AC adapter with a different voltage polarity, at the same time the AC voltage supplied from the terminal of the DC input jack 2 is rectified, and the rectified pulsating current voltage is converted to a DC voltage by an electrolytic capacitor 8 for smoothing, thus driving the electronic apparatus.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a transformer (hereinafter referred to as
It can be used as a power source using an AC adapter)
The present invention relates to a power supply circuit of an electronic device that can be used by switching two power supplies.

[0002]

2. Description of the Related Art Conventionally, some battery-powered electronic devices can be used by a commercial AC power source via an AC adapter. The AC adapter 50 is shown in FIG.
As shown in, an AC plug 52 for receiving a voltage supply from a commercial AC power supply, an AC power transformer 54 for converting the commercial AC power supply into a low voltage, a diode 56 for rectifying the voltage-converted AC voltage, and a rectifier And a DC output plug 60 for supplying a rectified voltage to an electronic device.

The DC output plug 60 outputs a DC voltage of a predetermined polarity, and the AC adapter 5
0 has a positive polarity. By connecting to the DC input jack 40 of the power supply circuit of the electronic device, the positive DC output of the DC output plug 60 of FIG. 4 is connected to the terminal a of the DC input jack 61 shown in FIG. The 0V output of the DC output plug 60 is input.

As shown in FIG. 5, the power supply circuit of the electronic apparatus has a DC input jack 61 for switching the voltage supply source according to the connection state of the AC adapter 50, a replaceable battery 62, and an output voltage. Is composed of an electrolytic capacitor 63 for smoothing, a diode 64 and a fuse 65 for preventing supply of a voltage different from the polarity desired by the electronic device. An internal circuit of the electronic device continues on the right side of FIG. 4 and is connected to the terminals d and e. The DC input jack 61 has a selector switch 66 for switching the power supply.
Is provided, and the terminal a and the terminal b are normally short-circuited.

Power supply voltage + E used inside electronic equipment
When the AC adapter 50 shown in FIG. 4 is connected, since the terminal a and the terminal b are separated by mounting the DC output plug 60, the changeover switch 66 is turned off, and the positive DC output of the DC output plug 60 of the AC adapter 50. Voltage is supplied from. On the contrary, when the AC adapter 50 is not connected, the changeover switch 66 in the DC input jack 61 is in the ON state, and the terminal a and the terminal b are electrically connected to each other, so that they are connected to the terminal b. A voltage is supplied from the positive terminal of the battery 62.

The AC adapter 70 shown in FIG. 6 has an AC plug 7 for receiving a voltage from a commercial AC power source.
2, an AC power supply transformer 74 for converting the commercial AC power supply into a low voltage, a diode 76 for rectifying the voltage-converted AC voltage, and an electrolytic capacitor 7 for smoothing the rectified voltage.
8 and DC for supplying rectified voltage to electronic devices
The output plug 80 and the DC output plug 80 output a DC voltage of a predetermined polarity.
The C adapter 70 has a negative polarity.

The conventional power supply circuit has a DC input jack 61.
When an AC adapter 70 having a different voltage polarity as shown in FIG. 6 is connected to the diode 64, a diode 64 is provided in order to prevent the electrolytic capacitor 63 shown in FIG. The terminal a and the terminal c are short-circuited with each other to generate an excessive current, and thereby the fuse 65 is melted to cut off the circuit.

[0008]

However, the power supply circuit as described above requires the AC adapter 50 for outputting a direct current with a predetermined voltage polarity as shown in FIG. Accordingly, the circuit inside the AC adapter 50 needs a diode 56 and a smoothing capacitor 58 for rectifying a commercial AC power source from AC to DC, and further requires a printed board on which these elements are mounted. . Therefore, the AC adapter tends to be large and it is difficult to reduce the size.

Further, for example, when the AC adapters 70 having different voltage polarities shown in FIG. 6 are connected, not only the electronic equipment cannot be driven, but also the elements of the internal circuit of the electronic equipment are destroyed. Therefore, as described above, in order to prevent element destruction, the fuse 65 and the diode 6 shown in FIG.
Special circuit protection elements such as 4 were required. However, this circuit protection element has the complexity of having to be replenished each time the circuit protection operation is performed.

The present invention has been made in order to solve the above-mentioned problems and eliminates the need for a rectifying diode and a smoothing capacitor inside a transformer, and a special circuit in a power supply circuit inside an electronic device. Provides a power supply circuit that protects the internal circuit of the electronic device when the connected transformer has different polarities without using a protective element and that can drive the electronic device even if a transformer that outputs alternating current is used. The purpose is to

[0011]

In order to achieve this object, the power supply circuit of the present invention is connected to a state in which it is driven by a DC power source by a battery and a transformer for converting a commercial AC power source into a voltage, so that the commercial An input for an electronic device that is driven by either an AC power source or a state in which the power supply source is switched between a DC power source using a battery and a commercial AC power source in response to attachment / detachment of the transformer. A jack, a voltage smoothing circuit for smoothing the supply voltage supplied through the input jack, and a reverse direction with respect to the application direction of the DC power by the battery when the transformer is attached to the input jack. And a rectifying circuit that cuts off a current that is about to flow.

The rectifier circuit may be a half-wave rectifier circuit, and the input jack has an anode terminal and a cathode terminal for receiving the output of the transformer, and an intermediate terminal connected to the anode of the battery. And a switch formed between an anode terminal and an intermediate terminal thereof and opened / closed in accordance with attachment / detachment of the transformer, and the half-wave rectification circuit connects the cathode of the battery and the cathode terminal of the input jack. A diode may be provided on the connecting circuit, and the anode may be connected to the cathode side of the battery and the cathode may be connected to the cathode terminal side of the input jack.

The rectifier circuit may be a full wave rectifier circuit.

[0014]

In the power supply circuit of the present invention having the above-mentioned structure, the rectifier circuit tries to flow in the direction opposite to the direction in which the DC power is applied by the battery when the input jacks are equipped with transformers having different voltage polarities. Current to shut off and protect the internal circuits of electronic devices. At the same time, when the AC voltage is supplied from the DC jack terminal, the power supply circuit rectifies the rectified current by the rectifying circuit, converts the rectified pulsating current voltage into the DC voltage by the voltage smoothing circuit, and uses it as a power source for electronic equipment. Drive.

[0015]

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

The AC adapter 10 is, as shown in FIG.
The AC plug 12 supplies commercial AC power to the AC power transformer 14, the AC power transformer 14 converts the commercial AC power into a low voltage, and the voltage output plug 16 outputs AC.

Further, as shown in FIG. 1, the power supply circuit of the electronic device has a DC input jack 2 for switching the voltage supply source according to the connection state of the AC adapter 10, a replaceable battery 4, and an input voltage. From the smoothing electrolytic capacitor 8 and the diode 6 connected between the cathode terminal of the replaceable battery 4 and the terminal c of the DC input jack 2 with the anode connected to the cathode terminal side of the battery 4 and the cathode connected to the terminal C side. It is configured. The internal circuit of the electronic device continues on the right side of FIG. 1, and is connected to the terminals d and e. The DC input jack 2 is provided with a changeover switch 3 for changing the power source, and short-circuits / opens the terminals a and b.

The electrolytic capacitor 8 corresponds to the voltage smoothing circuit of the present invention, the diode 6 corresponds to the rectifying circuit of the present invention, and the AC adapter corresponds to the transformer of the present invention.

In addition, the AC adapter 10 connects the voltage output plug 16 to the DC input jack 2 of the power supply circuit of the electronic device, so that the terminal a of the DC input jack 2 shown in FIG.
2, the output A of the voltage output plug 16 and the output B of the voltage output plug 16 are input to the terminal c of the DC input jack 2.

Then, as shown in FIG. 1, the power supply voltage + E used inside the electronic device is equal to the AC adapter 1 shown in FIG.
At the time of connection of 0, by inserting the voltage output plug 16 into the DC input plug 2, the terminals a and b of the changeover switch 3
By disconnecting, the voltage is supplied from the AC adapter 10. On the contrary, when the AC adapter 10 is not connected, the terminals a and b in the DC input jack 2 are connected, and therefore the anode of the replaceable battery 4 connected to the terminal b of the DC input jack 2 is connected. Voltage is supplied from the terminal.

The diode 6 has a rectifying function. Thereby, the electrolytic capacitor 8 and the internal circuit of the electronic device are prevented from being ruptured or destroyed by the supply of the voltage different from the predetermined polarity to the input jack.

For example, when an AC voltage is applied between the terminals a and c of the DC input jack 2 by connecting the AC adapter 10 shown in FIG. 2, a pulsating voltage half-wave rectified by the diode 6 is generated. At the same time, due to the smoothing action of the electrolytic capacitor 8, a DC voltage having a normal polarity is generated between the terminals d and e, and the electronic device can operate.

When a positive output AC adapter 50 as shown in FIG. 4 is connected to the DC input jack 2 of FIG. 1, the diode 6 carries a forward bias current,
A voltage of normal polarity is applied between the terminals d and e, and the electronic device can operate.

In addition, as shown in FIG.
When the adapter 70 is connected to the DC input jack 2 of FIG. 1, the diode 6 cuts off the current by the reverse bias, so that the reverse voltage is not applied between the terminals d and e,
Protects internal circuits of electronic devices. Although the electronic device cannot operate, it does not enter into an unrecoverable state because the circuit is not cut off by fusing with a reverse polarity voltage unlike the protection circuit using the fuse 65 shown in FIG.

In this embodiment, the diode 6 is provided between the cathode terminal of the battery 4 and the terminal c of the DC input jack 2 as shown in FIG. 1, so that the diode 6 is not used when driving the battery. The voltage can be supplied. The reason is not only that the battery 4 does not require rectification because it has a DC output, but it also suppresses the wasted power consumed through the diode 6 and extends the life of the battery.

In addition to the present embodiment, the power supply circuit of the present invention is
In the power supply circuit shown in FIG. 1, the battery 4, the diode 6, and the electrolytic capacitor 8 may have their respective anodes (anodes) and cathodes (cathodes) interchanged and connected. In the case of this power supply circuit, the AC adapter 10 shown in FIGS.
When 70 is used, the electronic device is made operable, and FIG.
When the AC adapter 50 shown in is used, the power supply circuit protects the internal circuit.

Further, as shown in FIG. 3, the power supply circuit of the electronic device of the present invention has four diodes 2 so that full-wave rectification can be performed between the terminals a and c of the DC input jack 22.
It is also possible to provide 6, 28, 30, 32 in the shape of a bridge. This power supply circuit includes a DC input jack 22 having a power supply changeover switch 23, a replaceable battery 24, and an electrolytic capacitor 3 for smoothing the input voltage, as in FIG.
Have four.

Then, for example, when the AC adapter 50 as shown in FIG. 4 is connected to the DC jack 22 of FIG. 3, the diode 28 and the diode 30 cause a current to flow in the forward bias, so that the terminals d and e are connected. A voltage having a normal polarity is applied to the electronic device, and the electronic device can operate. At the same time, when the AC adapter 70 as shown in FIG. 6 is connected to the DC jack 22 of FIG.
Since a current is caused to flow forward by the diode 2 and the diode 26, a voltage having a normal polarity is applied between the terminals d and e, and the electronic device can operate. That is, in this full-wave rectification type power supply circuit, the terminals a and c of the DC input jack 22 are
Even if a positive polarity, a negative polarity, or an AC voltage is applied in between, a voltage of normal polarity is always generated between the terminals d and e.

The diode used in the power supply circuit of this embodiment is desired to be as efficient as possible.

[0030]

As is apparent from the above description,
In the power supply circuit of the present invention, since circuit protection and rectification are performed by the rectifier circuit, no special circuit protection element is required in the internal circuit of the electronic device, and the circuit can be simplified. At the same time, since a rectifying diode and a smoothing capacitor inside the AC adapter used for electronic equipment are not required, the AC adapter can be downsized and can be driven by an inexpensive AC type AC adapter.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of a power supply of an electronic device of the present invention.

FIG. 2 is a circuit diagram showing a configuration of an AC adapter that can be used in the present invention.

FIG. 3 is a circuit diagram showing an embodiment of the present invention.

FIG. 4 is a circuit diagram showing a configuration of a general AC adapter.

FIG. 5 is a circuit diagram showing a configuration of a power supply of a conventional electronic device.

FIG. 6 is a circuit diagram showing a configuration of an AC adapter having different voltage polarities.

[Explanation of symbols]

 2 DC input jack 3 Changeover switch 4 Dry battery 6 Diode 8 Electrolytic capacitor

Claims (4)

[Claims] 1. A state of being driven by a DC power source using a battery,
By connecting a transformer that converts the voltage of the commercial AC power supply,
In a power supply circuit of an electronic device driven in any one of the state of being driven by the commercial AC power supply, a power supply source is provided between the DC power supply by the battery and the commercial AC power supply in correspondence with the attachment / detachment of the transformer. An input jack to be switched, a voltage smoothing circuit to smooth the supply voltage supplied through the input jack, and a reverse direction to the DC power supply direction by the battery when the transformer is attached to the input jack. A power supply circuit, comprising: a rectifier circuit that interrupts a current that tends to flow in a direction. 2. The power supply circuit according to claim 1, wherein the rectifier circuit is a half-wave rectifier circuit. 3. The input jack is formed between an anode terminal and a cathode terminal for receiving the output of the transformer, an intermediate terminal connected to the anode of the battery, and the anode terminal and the intermediate terminal, The half-wave rectifier circuit includes a diode on the circuit connecting the cathode of the battery and the cathode terminal of the input jack, and an anode on the cathode side of the battery, 3. The cathode is connected to the cathode terminal side of the input jack.
Power supply circuit described in. 4. The power supply circuit according to claim 1, wherein the rectifier circuit is a full-wave rectifier circuit.