JP2007228643A - Ac adapter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a cost, and prevent an overcharge of a secondary battery and a quick charge by a large current. <P>SOLUTION: Power supply circuits 1, 2, 3 obtain a DC voltage output from an AC power supply AC by using an AC-DC conversion. A connection cable 4 and a connection connector 5 capture a charge request signal of the secondary battery from a notebook computer PC as a portable electronic device. A signal conversion circuit 6 and an insulation circuit 7 convert the charge request signal into an on/off signal. A switch 8 is controlled so as to be turned on, and supplies outputs from the power supply circuits to the portable electronic device as an external power supply when the charge request signal requests to charge the secondary battery. The switch 8 is controlled so as to be turned off, and interrupts the outputs from the power supply circuits when the charge request signal does not request to charge the secondary battery. The charge request signal is monitored by a remaining capacity checking means of the secondary battery in the portable electronic device, and captured as an ultrasonic signal or an optical signal instead of a cable connection. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an AC adapter that externally supplies power to a portable electronic device that incorporates a secondary battery (battery) and charges the secondary battery, and more particularly to an AC adapter that incorporates an output control function.

  Portable electronic devices (laptops, video cameras, etc.) have a secondary battery as a power source. The portable operating power source is a secondary battery. The indoor operating power source is a secondary battery or an external AC adapter. Use power. This AC adapter is also used as a secondary battery charger.

  FIG. 3 shows the basic configuration of the AC adapter. The transformer 1 takes in an alternating current that has been stepped down from a commercial alternating current power supply AC, the rectifier diode circuit 2 rectifies the alternating current from the transformer 1, and the smoothing circuit 3 rectifies. By smoothing the direct current from the diode circuit 2, low voltage direct current power can be output.

  A portable electronic device such as a notebook personal computer takes in power necessary for operation from the AC adapter and charges a secondary battery while the AC adapter is connected. In this charge, the overcharge of the secondary battery reduces its life. Further, rapid charging with a large current has disadvantages such as overheating of the secondary battery.

As these countermeasures, there is one that takes in a charging state signal of a secondary battery from a portable electronic device into an AC adapter and controls the output of the AC adapter based on this signal. This control method automatically switches between an adapter mode that supplies operating power to the portable electronic device and a charging mode that charges the secondary battery. In the adapter mode, a large amount of current is supplied at a relatively low voltage. However, a relatively low current is supplied at a high voltage (see, for example, Patent Document 1).
JP-A-8-237862

  In the conventional AC adapter with a control function, many circuit elements and control means are required to realize the automatic switching function between the adapter mode and the charging mode. Specifically, the conventional AC adapter has two types of power supply circuit configurations that differ depending on the output current and voltage, and as a signal input circuit, detects the state of charge of the secondary battery, and detects whether or not the portable electronic device is connected to the AC adapter. In addition, a control circuit (or a microcomputer) for controlling mode switching based on these signals and a changeover switch are required, which is expensive.

  An object of the present invention is to provide an AC adapter capable of preventing secondary batteries from being overcharged and preventing rapid charging due to a large current while reducing costs.

  In order to solve the above-mentioned problems, the present invention uses a battery remaining amount check function of a portable electronic device, and uses the battery charge request signal from the portable electronic device to an AC adapter as a battery charge request signal. The AC adapter supplies power to the portable electronic device only when there is a request for battery charging, so that the battery is always used as the operating power, and the AC adapter supplies operating power and charges the battery only when the battery level is low. And is characterized by the following configuration.

(1) An AC adapter for externally supplying power to a portable electronic device incorporating a secondary battery and charging the secondary battery,
A power supply circuit for obtaining a DC voltage output from an AC power supply by AC-DC conversion;
Means for capturing a charge request signal for the secondary battery from the portable electronic device;
When the charging request signal is required to charge the secondary battery, it is turned on to supply the output of the power circuit as an external power source to the portable electronic device, and the charging request signal is not required to charge the secondary battery Is provided with a switch which is controlled to be off and cuts off the output of the power supply circuit.

  (2) The charge request signal is monitored by a remaining battery level check means of the portable electronic device and is captured by cable connection, or is captured by an ultrasonic signal or an optical signal. .

  As described above, according to the present invention, the fact that the remaining battery level is lower than the threshold value is taken into the AC adapter from the portable electronic device as a battery charge request signal, and the AC adapter is transferred to the portable electronic device only when there is a battery charge request. Since the power is supplied, it is possible to prevent the secondary battery from being overcharged and to prevent rapid charging due to a large current.

  In addition, the circuit configuration requires additional battery charge request signal input / output means and switch means for on / off control between the power supply circuit and the portable electronic device, which is less expensive than conventional AC adapters. You can go down.

  FIG. 1 is a circuit configuration diagram of an AC adapter with a built-in control function according to an embodiment of the present invention. The transformer 1, the rectifier diode circuit 2, and the smoothing circuit 3 are configured as a power circuit by AC-DC (AC-DC) conversion equivalent to that of a conventional AC adapter, and are defined in a notebook personal computer PC as a portable electronic device. Get voltage output.

  In addition to these circuits, circuit elements 4 to 10 are provided in this embodiment. One end of the connection cable 4 is connected to the USB or serial I / O of the notebook computer PC, and takes in a battery charge request signal from the notebook computer PC. This battery charge request signal is obtained from a battery remaining amount check function of the notebook personal computer PC. This check function is to monitor the remaining battery level from the battery voltage and charge / discharge amount, and when the remaining battery level falls below the threshold value, it flashes on the notebook PC or warns on the screen. This monitoring signal is captured as a battery charge request signal.

  The connection connector 5 is connected to the other end of the connection cable 4 and takes in a battery charge request signal into the AC adapter. The signal conversion circuit 6 determines the presence / absence of a battery charge request signal through the connection connector 5 and converts it into an on / off hold signal.

  The insulation circuit 7 has, for example, a photocoupler configuration, and electrically isolates and amplifies and extracts the on / off hold signal from the signal conversion circuit 6. The switch 8 is configured as a semiconductor switch or a control relay and is on / off controlled. When the on / off hold signal from the insulating circuit 7 is in the on state, the switch 8 is turned on to extract the DC output of the smoothing circuit 3.

  The power output terminal 9 is used as a DC output lead terminal from the switch 8 and is connected to an external power cable 10 of the notebook personal computer PC. A connector (not shown) that can be connected to an external power input terminal of the notebook personal computer PC is provided at the tip of the external power cable 10.

  The power supply from the AC adapter configured as described above to the notebook computer PC is executed in accordance with a battery charge request signal from the notebook computer PC. This power supply is performed according to the operation flowchart shown in FIG.

  In the figure, the notebook personal computer PC periodically checks the remaining battery level when it is activated (S1), and determines whether or not the remaining battery level is below the threshold value (S2). This determination is whether or not battery charging is necessary and is output to the AC adapter as an on / off battery charging request signal.

  When the input battery charging request signal requires battery charging, the AC adapter turns on the switch 8 (S3) and supplies external power to the notebook personal computer PC (S4). If the battery charge request signal does not require battery charging, the switch 8 is turned off (S5), the power supply to the notebook personal computer PC is cut off, and the notebook personal computer PC is driven only by the battery (S6).

  Therefore, even when the notebook personal computer PC is connected to the AC adapter, the notebook personal computer PC operates using the battery as a power source when it is not necessary to charge the battery. When the battery is discharged and the amount of charge falls below the threshold value, the operation is continued using the AC adapter as a power source, and the battery is charged in parallel with this operation. When the battery charging is completed, the switch 8 is controlled to be turned off again to supply power by the battery alone.

  In this control, when power is supplied from the AC adapter to the notebook computer PC, the current necessary for the CPU, display, etc. in the notebook computer PC and the charging current of the battery are supplied. Will never charge you. Moreover, since the AC adapter is disconnected when the charging of the battery is completed, the battery is not overcharged.

  In the embodiment, the case where the battery charge request signal is taken into the AC adapter by cable connection is shown, but it can be replaced with other signal input / output means. For example, a battery charge request signal is transmitted from the notebook personal computer PC to the AC adapter using an ultrasonic signal or an optical signal. In these cases, since insulation is also ensured, a conversion circuit for sound waves and optical signals is required on the AC adapter side, but the insulation circuit 7 is unnecessary.

  In the embodiment, the power supply circuits (1 to 3) can be appropriately changed in design. For example, a power supply circuit having a constant voltage circuit can be used. In this case, the function of the switch 8 can be given to the constant voltage circuit, and the switch 8 can be omitted.

The circuit block diagram of the AC adapter with a built-in control function showing the embodiment of the present invention. The operation | movement flowchart in embodiment. The basic block diagram of the conventional AC adapter.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transformer 2 Rectifier diode circuit 3 Smoothing circuit 4 Connection cable 5 Connection connector 6 Signal conversion circuit 7 Insulation circuit 8 Switch 9 Power supply output terminal 10 External power supply cable

Claims (2)

An AC adapter for externally supplying power to a portable electronic device containing a secondary battery and charging the secondary battery,
A power supply circuit for obtaining a DC voltage output from an AC power supply by AC-DC conversion;
Means for capturing a charge request signal for the secondary battery from the portable electronic device;
When the charging request signal is required to charge the secondary battery, it is turned on to supply the output of the power circuit as an external power source to the portable electronic device, and the charging request signal is not required to charge the secondary battery An AC adapter comprising: a switch that is controlled to be off and cuts off the output of the power supply circuit. 2. The charge request signal is monitored by a remaining battery remaining amount check unit of the portable electronic device, and is captured by cable connection, or is captured by an ultrasonic signal or an optical signal. AC adapter as described in 2.

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