JP3227680B2 - AC adapter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an AC adapter for supplying predetermined DC power to various portable electronic devices such as a notebook personal computer and a printer.

[0002]

2. Description of the Related Art In recent years, in various portable electronic devices such as notebook personal computers and printers, in order to promote the reduction in size and weight of the device itself, a power supply section is separated from the device body, and the main body is separated by a separate AC adapter. Power is supplied to Such an AC adapter includes a primary connector serving as a power plug connected to an AC power supply, a secondary connector connected to a load such as a device main body, and an AC power applied from the primary connector converted to a predetermined DC power. And an AC-DC conversion unit for converting.
The DC power obtained by the AC-DC converter is supplied to the load via the secondary connector.

[0003]

In the above-mentioned prior art, not only the required voltages of the load-side equipment main units are different from each other, but also the shapes of the secondary-side connectors are not unified, and However, even if the shape of the secondary connector is similar, there is a problem that the voltage polarity is different. Therefore, a dedicated AC adapter must be prepared for each device main body, and the versatility and portability have been extremely impaired.

[0004] Therefore, the present invention eliminates the above problems,
In response to a wide variety of electronic devices connected as loads,
If the input voltage polarity of the load connected to the secondary connector is positive or negative
An object of the present invention is to provide an AC adapter that supplies DC power of an appropriate polarity and prevents erroneous output of DC power of a reverse polarity to a load.

[0005]

According to the present invention, there is provided an AC adapter comprising: a primary connector connected to an AC power supply; a secondary connector connected to a load; and an AC adapter applied from the primary connector. An AC-DC converter configured to convert power to a predetermined DC power and output the DC power to the secondary connector, a polarity for determining an input voltage polarity of a load connected to the secondary connector. A determination unit, and the second unit is provided in accordance with a determination result by the polarity determination unit.
Output for switching the voltage polarity output from the secondary connector to the load
It has a force polarity switching unit .

The AC adapter according to claim 2 is
A switch is provided between the AC-DC converter and the secondary connector.
A switch is provided, and according to the determination result by the polarity determination unit,
Switching the voltage polarity output from the secondary side connector to the load
The voltage output to the load by the switch until
Is configured to shut off the supply of water .

The AC adapter according to claim 3 is
A load current measuring unit that detects the load current, and a load connection state monitoring unit that operates the polarity determination unit when a load is disconnected from the secondary connector based on a detection signal from the load current measuring unit. It is provided with.

[0008]

[Action] The arrangement of claim 1, the input voltage polarity of the load connected between the secondary side connector, pre-determined by the polarity judging unit in the AC adapter, the input voltage of the load is determined by the polarity determination unit In accordance with the polarity, the voltage polarity output from the secondary connector to the load via the output polarity switching unit is switched. This allows the load to be connected to the secondary connector
Proper polarity regardless of whether the input voltage polarity is positive or negative.
Can be supplied simply and reliably.

According to the configuration of claim 2, the polarity judging section
The power output from the secondary connector to the load according to the judgment result
Output to load by switch until piezo polarity is switched
The supply of voltage is cut off.

According to the third aspect of the present invention, if the load is disconnected from the secondary connector while a predetermined DC power is being supplied to the load, the load connection state monitoring unit connects the load again, and The polarity determining unit is operated until the polarity is determined.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. In FIG. 1 showing the basic configuration of an AC adapter according to the present invention, reference numerals 1, 1 'denote primary connectors as power plugs connected to an AC power supply 2,
The AC power applied from the AC power supply 2 via the primary connectors 1 and 1 'is constituted by a main converter for generating a DC output voltage + V and a sub converter for generating DC test voltages + Vt and -Vt. Is converted into a predetermined DC power by the AC-DC conversion unit 3 and the secondary connectors 4, 4 '.
Output in between. Reference numeral 5 denotes a voltage setting unit connected to the AC-DC conversion unit 3. By operating a changeover switch (not shown) provided in the voltage setting unit 5, the voltage setting unit 5 responds to a load-side required voltage described later. Thus, the DC output voltage + V can be appropriately set and changed. AC-D
A DC output voltage + V line between the C converter 3 and the secondary connector 4 is provided as a switch for supplying / cutting off the DC output voltage + V between the secondary connectors 4 and 4 ′.
Of the main relay contacts 6 are inserted and connected.

Reference numeral 7 denotes a test voltage switching relay for selectively supplying a DC test voltage + Vt or a DC test voltage -Vt for polarity determination between the secondary connectors 4, 4 'when the main relay contact 6 is turned off. It is a contact point. The common terminal of the test voltage switching relay contact 7 and the DC output voltage + V
A series circuit of a current limiting resistor 8 and a test current measuring unit 9 for detecting a test current flowing through the resistor 8 line is connected between the lines. 10 is the secondary connector 4, 4
, A load-end voltage measuring unit for detecting a load-side voltage connected to the load current measuring unit, and a load-current measuring unit 11 for detecting a load current. These test-current measuring unit 9, load-end-voltage measuring unit 10, and load-current measuring unit A detection signal from 11 is input to a CPU 12 as a control unit having a built-in input / output interface (not shown). On the other hand, reference numeral 13 denotes a polarity switching relay contact for switching the polarity of the DC output voltage + V from the secondary side connectors 4, 4 'to the load side as an output polarity switching unit. Although not specifically shown in the drawing, the polarity switching relay contact 13
, Together with the main relay contact 6 and the test voltage switching relay contact 7, are operated by a relay drive signal output from the CPU 12. Also, CPU
A display unit 14 such as an LED is connected to 12 so that the polarity on the load side is displayed.

According to the present invention, a device body requiring an AC adapter is designed by incorporating a protection circuit as shown in an equivalent circuit of FIG. 2 or 3 in advance in order to protect the device main body from damage due to reverse connection of the power supply. It is based on the knowledge that That is, in the equivalent circuit shown in FIG. 2, a diode 16 for blocking a reverse voltage is inserted and connected to an input voltage line of a load 15 which is a power supply input circuit. On the other hand, the equivalent circuit shown in FIG. 3 has a diode 17 connected in parallel with the load 15 and a fuse 18 inserted and connected to the input voltage line of the load 15. In this case, a current flows through the diode 17 to immediately blow the fuse 18.
The resistance 8 in FIG. 1 is a DC test voltage + V
The fuse 18 is provided to prevent the fuse 18 from being blown when t and -Vt are supplied to the load 15.

Next, an input / output block configuration around the CPU 12 will be described in detail with reference to FIG. The CPU 12 responds to the detection signals from the test current measuring section 9 and the load-end voltage measuring section 10 by connecting the loads connected to the secondary connectors 4, 4 '.
In accordance with a detection signal from the load current measuring unit 11, whether the load 15 is connected between the secondary connectors 4, 4 'is monitored. After the load 15 is disconnected from the secondary connectors 4, 4 ', the load
And a load connection state monitoring unit 22 for operating the polarity determination unit 21 until the polarity is determined. Then, while executing a predetermined processing procedure based on a program stored in the CPU 12, a polarity drive signal is supplied from the polarity determination unit 21 to the main relay contact 6, the test voltage switching relay contact 7, and the polarity switching relay contact 13, and the display unit Indicate the polarity of the load 15 via 14.

Next, the AC adapter having the above configuration will be described.
The operation will be described with reference to the flowcharts shown in FIGS. First, the procedure for determining the polarity of the load 15 will be described. As shown in FIG. 5, by turning off the main relay contact 6 in response to a relay drive signal from the CPU 12, the DC output to the secondary-side connectors 4, 4 'is established. The supply of the voltage + V is cut off and the polarity switching relay contact 13 is set to the positive polarity (FIG. 1).
Position). Then, the test voltage switching relay contact 7 is switched so that the DC test voltage + Vt is supplied between the secondary connectors 4, 4 '. At this time, the CPU 12
Based on the detection signals from the test current measurement unit 9 and the load terminal voltage measurement unit 10, the value of the test current Ip and the value of the load terminal voltage Vp are stored and held, respectively. Thereafter, the CPU 12 switches the test voltage switching relay contact 7 so that the DC test voltage -Vt is supplied between the secondary side connectors 4 and 4 ', and the value of the test current Im and the value of the load terminal voltage Vm in this state. Are stored in the same manner.

The measured current values Ip,
Based on Im and the voltage measurement values Vp, Vm, the polarity determination unit 21 of the CPU 12 determines the connection state of the load 15 between the secondary connectors 4, 4 'according to the flowchart of FIG. First, when the connection between the secondary connectors 4 and 4 'is open, the values of the test currents Ip and Im when the DC test voltages + Vt and -Vt are supplied become 0. Accordingly, when the current measurement values Ip and Im are both 0, the polarity determination unit 21 determines that the load 15 is not connected (step S1), and returns to the procedure of the flowchart of FIG.
Im and voltage measurement values Vp and Vm are measured. Next, when the measured current value Im when the DC test voltage −Vt is supplied is 0 and the measured current value Ip when the DC test voltage + Vt is supplied indicates a certain value, the polarity determination unit 21 determines whether the DC test voltage −Vt is supplied. Diode of equivalent circuit in FIG. 2 when voltage -Vt is supplied
16 determines that the current has been interrupted, and determines that the load 15 has been connected in a forward direction (step S2). Conversely, when the measured current value Ip when the DC test voltage + Vt is supplied is 0 and the measured current value Im when the DC test voltage −Vt is supplied indicates a certain value, the polarity determination unit 21 determines whether the DC test voltage + Vt is supplied. Voltage + Vt
It is determined that the diode 16 of the equivalent circuit in FIG. 2 has interrupted the current at the time of supply, and it is determined that the load 15 has been reversely connected (step S3).

On the other hand, if both the current measurement value Ip and the current measurement value Im indicate a certain value, the process proceeds to step S4.
In S5, the polarity determination unit 21 determines the voltage measurement value Vm when the DC test voltage −Vt is supplied and the DC test voltage + V
It is determined whether the voltage measurement value Vp when t is supplied is small. This is because when the equivalent circuit in FIG. 3 is connected between the secondary connectors 4 and 4 ′, a large current flows from the anode to the cathode of the diode 17 when a reverse voltage is applied to the load 15. And load end voltage measurement unit 10
This is based on the fact that the load-end voltages Vp and Vm measured by (1) and (2) show a small value almost in agreement with the forward voltage drop of the diode 17. That is, when the measured voltage value Vm when the DC test voltage −Vt is supplied is a small value of about the forward voltage drop of the diode 17, the polarity determination unit 21 determines that the load 15 is connected in the forward direction. Conversely, DC test voltage +
The measured voltage Vp when Vt is supplied is
If the value is as small as the forward voltage drop, the polarity determining unit 21 determines that the load 15 is reversely connected. Further, when both the current measurement value Ip and the current measurement value Im indicate a certain value and the voltage measurement value Vp and the voltage measurement value Vm indicate a value larger than the forward drop voltage of the diode 17, the polarity determination unit 21 compares the measured voltage value Vp with the measured voltage value Vm (step S6). At this time, the measured voltage value Vp
Is larger than the voltage measurement value Vm, the polarity determination unit 21 determines that the load 15 is connected in order, and if the voltage measurement value Vm is larger than the voltage measurement value Vp, the polarity determination unit 21
Are determined to be reverse-connected.

This series of steps is performed until the polarity determination unit 21 completes the polarity determination of the load 15 as shown in the flowchart of FIG. As a result, the load is
If it is determined that the load connection 15 is the forward connection, the polarity switching relay contact 7 is switched to the positive polarity position. If the load 15 is determined to be the reverse connection, the polarity switching relay contact 7 is set to the reverse polarity. , The polarity switching relay contact 7 is set to the appropriate position of the load 15, and the polarity of the load 15 is displayed via the display unit 14. And the main relay contact 6
Is turned on, and the load is connected via the secondary connectors 4, 4 '.
The normal operation of the AC adapter is performed by supplying the DC output voltage + V of an appropriate polarity to 15. At this time, when the disconnection of the load 15 from the secondary-side connectors 4 and 4 ′ is detected by the load connection state monitoring unit 22 based on the detection signal from the load current measurement unit 11, the load connection state monitoring unit 22
Controls the polarity determination unit 21 so that the polarity determination of the load 15 in the above processing procedure is performed again. Therefore, the main relay contact 6 is turned off until the load 15 is connected again between the secondary connectors 4 and 4 ', and the supply of the DC output voltage + V to the outside is forcibly shut off.

As described above, according to the above embodiment, the test current Ip and the load terminal voltage Vp when the DC test voltage + Vt is supplied between the secondary side connectors 4 and 4 ', and the DC test voltage-
Test current Im and load terminal voltage Vm when Vt is supplied
And a polarity determination unit 21 that determines the input voltage polarity of the load 15 connected between the secondary-side connectors 4 and 4 ′ based on the current measurement values Ip and Im and the voltage measurement values Vp and Vm. Provided in a conventional AC adapter, it is possible to supply DC power of an appropriate polarity from the determination result by the polarity determination unit 21 in accordance with various electronic devices connected as the load 15. become,
An AC adapter with excellent versatility and portability can be provided.

A polarity switching relay contact 13 for switching the voltage polarity output from the secondary connectors 4, 4 'to the load 15 in accordance with the result of the determination by the polarity determining unit 21 is provided in the AC adapter. Just connect to secondary side connectors 4, 4 '
Regardless of whether the input voltage polarity of the load 15 to be applied is positive or negative, it is possible to easily and reliably supply DC power having an appropriate polarity to the load 15.

Also, according to the result of the judgment by the polarity judgment unit 21,
Output from the secondary connectors 4, 4 'to the load 15
To the load 15 by the main relay contact 6 until the characteristic is switched
The supply of the output voltage can be cut off.

Further, the load current during normal operation of the AC adapter is constantly detected by the load current measuring section 11, and the load 15 is transmitted from the secondary connectors 4, 4 'based on this detection signal.
Is disconnected, the load connection state monitoring unit 22 causes the polarity determination unit 21 to perform the polarity determination of the load 15 again,
Even if the load 15 of the opposite polarity is connected after the 15 is temporarily disconnected, the polarity determination unit 21 supplies the DC output voltage + V of the appropriate polarity to the newly connected load 15. be able to. Therefore, it is possible to prevent the DC power having the opposite polarity from being output to the various electronic devices connected as the load 15 by mistake.

Next, a specific circuit example obtained from the basic configuration diagram of the AC adapter in FIG. 1 will be described with reference to FIG. In the figure, the same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description of the common parts is omitted. The configuration inside the CPU 12 is the same as that in FIG.

In this circuit example, the AC-DC converter 3
Is a well-known ringing choke comprising an input rectifier circuit 31 connected between both ends of the primary connectors 1 and 1 ', an N-channel junction type FET 32, a resistor 33 and a transformer 34.
It comprises a converter and a rectifying and smoothing circuit composed of diodes 35 and 36 and smoothing capacitors 37 and 38 connected to the secondary side of the transformer 34. When the gate potential of the FET 32 rises, the FET 32 turns on, the input voltage from the input rectifier circuit 31 is applied to the primary winding 34a of the transformer 34, and the FET 32 is rapidly turned on by the voltage generated between the primary windings 34b. Turn on. At this time, the transformer
The voltage induced in the secondary windings 34c and 34d of the 34 is a diode
Electromagnetic energy is applied in the opposite directions of 35 and 36, and electromagnetic energy is accumulated in each of the secondary windings 34c and 34d. Thereafter, when the current flowing through the primary winding 34a is only the exciting current of the transformer 34, the voltage between the respective primary windings 34a and 34b decreases, and a voltage in the opposite direction is applied to the gate of the FET 32, so that the FET 32 Turns off rapidly. The electromagnetic energy stored in the secondary windings 34c and 34d is supplied to the output side via diodes 35 and 36, and when all the electromagnetic energy is emitted from the secondary windings 34c and 34d, the gate of the FET 32 is again turned on. The potential rises and the same operation is repeated, resulting in a DC output voltage + V,-
V is output. Although not shown in this figure,
In order to stabilize the DC output voltages + V and -V, a feedback loop including an output voltage detection circuit is provided, and the reference voltage of the output voltage detection circuit is switched by the voltage setting unit 5 in FIG. The voltage values of + V and -V can be appropriately changed to, for example, +6 V, +12 V, and +18 V.

On the other hand, a reference voltage (for example, +2.5 V) obtained by dividing the DC output voltage + V by resistors 43 and 44 is applied to the non-inverting input terminals of the operational amplifiers 41 and 42. The DC output voltage + V is applied to the power supply terminal of one operational amplifier 41, and the DC output voltage −V is applied to the power supply terminal of the other operational amplifier 42. And CPU
By applying a control voltage of, for example, +0 V or +5 V from the twelve control terminals P4, P5 to the inverting input terminals of the operational amplifiers 41, 42, the DC test voltages + Vt, -V having substantially the same value as the DC output voltages + V, -V. Vt is equal to each operational amplifier 41,
Generated at the 42 output terminal. That is, the pair of operational amplifiers 41 and 42 are used in place of the test voltage switching relay contact 7.

The test current measuring section 9 and the load terminal voltage measuring section
10 and a load current measuring unit 11 are both built in a one-chip CPU 12 having an A / D converter, and connect the voltage value of the output terminal of the operational amplifier 41 to the connection point between the main relay contact 6 and the polarity switching relay contact 13. And the voltage value on the cathode side of the diode 45 inserted and connected between the ground lines, the input terminals IN0, IN1, IN1 of the CPU 12.
2, respectively. Then, the test current measuring section 9 obtains a potential difference between the resistors 8 based on a voltage difference between the input terminal IN0 and the input terminal IN1, and divides the potential difference by a resistance value of the resistor 8 to double the same, thereby obtaining the test current. Ip,
Calculate Im. Further, the load terminal voltage measuring unit 10 measures the voltage value of the input terminal IN1 as load terminal voltages Vp and Vm. Further, the load current measuring section 11 has an input terminal IN0 and an input terminal I in the same manner as the test current measuring section 9.
The load current is measured based on the voltage value of N2. In addition,
Resistors 46, 47 and 48 are inserted and connected to the input terminals IN0, IN1 and IN2 lines, respectively.

Between the control terminals P0 and P1 of the CPU 12 and the reference voltage terminal VREF, LEDs 5 constituting the display unit 14 are provided.
A series circuit of 1, 52 and current limiting resistors 53, 54 is connected. The control terminals P2 and P3 of the CPU 12 are connected to the bases of transistors 57 and 58 via resistors 55 and 56, respectively. A main relay is connected between the collectors of the transistors 57 and 58 and the reference voltage terminal VREF. The coil 6a of the contact 6 and the coil 13 of the polarity switching relay contact 13
a is inserted and connected, and a relay drive signal is supplied from the control terminal P2 or the control terminal P3, the transistors 57 and 58
Are turned on, the coils 6a and 13a are energized, and the main relay contact 6 and the polarity switching relay contact 13 are switched. Then, by performing a series of processing procedures such as polarity determination in accordance with the flowcharts of FIGS. 5 to 7, it is possible to achieve the same operations and effects as in the above-described embodiment.

The present invention is not limited to the above embodiment, and various modifications can be made within the scope of the present invention. For example, A inside the AC adapter
Each circuit configuration such as a C-DC conversion unit and a polarity determination unit is as follows.
Various types can be applied in consideration of output power and the like. In addition, the procedure for determining the load polarity shown in the above embodiment is merely an example, and a suitable determination procedure that is more convenient can be obtained by appropriately changing the program in the CPU. Furthermore, A
In order to reduce the size of the C adapter, the output polarity switching unit is not limited to the relay in the embodiment, and other switch means may be used.

[0029]

According to the first aspect of the present invention, the AC adapter includes a primary connector connected to an AC power supply, a secondary connector connected to a load, and an AC power applied from the primary connector. An AC-DC converter for converting the DC power into DC power and outputting the DC power to the secondary connector.
In the adapter, determining polarity determination unit is provided an input voltage polarity of the connected to the secondary side connector load, the poles
The secondary side connector according to the determination result by the
Output polarity switching unit that switches the voltage polarity output from the load to the load
Are those having a, corresponding to a wide variety of electronic devices to be connected as a load, the load connected to the secondary side connector
Regardless of whether the input voltage polarity is positive or negative, it is possible to easily and reliably supply DC power having an appropriate polarity.

The AC adapter according to claim 2 is
A switch is provided between the AC-DC converter and the secondary connector.
A switch is provided, and according to the determination result by the polarity determination unit,
Switching the voltage polarity output from the secondary side connector to the load
The voltage output to the load by the switch until
Are those configured to block the supply of, polarity determination
Output from the secondary connector to the load according to the
The voltage polarity of the force to obtain switching, the load by the switch
The supply of the output voltage can be cut off.

The AC adapter according to claim 3 is
A load current measuring unit that detects the load current, and a load connection state monitoring unit that operates the polarity determination unit when a load is disconnected from the secondary connector based on a detection signal from the load current measuring unit. This can prevent erroneous output of DC power to the load to the load.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of an AC adapter according to an embodiment of the present invention.

FIG. 2 is an equivalent circuit diagram of a device main body connected to the AC adapter.

FIG. 3 is an equivalent circuit diagram of a device main body connected to the AC adapter.

FIG. 4 is a block diagram of essential parts of the same.

FIG. 5 is a flowchart showing a polarity determination procedure according to the first embodiment;

FIG. 6 is a flowchart showing a polarity determination procedure according to the first embodiment;

FIG. 7 is a flowchart showing an operation procedure after the polarity determination.

FIG. 8 is a circuit diagram of an AC adapter showing a specific example of the present invention.

[Explanation of symbols]

 1, 1 'primary connector 2 AC power supply 3 AC-DC converter 4, 4' secondary connector 6 main relay contact (switch) 13 polarity switching relay contact (output polarity switching unit) 15 load 21 polarity determination unit 22 load Connection status monitor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References Open to the public Showa 64-9425 (JP, U) Open to the public Showa 62-191333 (JP, U) Open to the public Showa 59-106072 (JP, U) (58) Field (Int.Cl. ⁷ , DB name) G01R 19/14 G05F 1/56 320

Claims (3)

(57) [Claims] A primary connector connected to an AC power supply, a secondary connector connected to a load, and converting AC power applied from the primary connector into predetermined DC power to convert the secondary power into a predetermined DC power. In an AC adapter constituted by an AC-DC conversion unit for outputting to a connector, a polarity judgment unit for judging the input voltage polarity of a load connected to the secondary connector is provided, and the polarity judgment unit responds to the judgment result by the polarity judgment unit. hand
Switching the voltage polarity output from the secondary side connector to the load
An AC adapter comprising an output polarity switching unit . 2. An AC-DC converter and said secondary-side connector.
The switch is provided between the
Output to the load from the secondary connector according to the fixed result
Until the voltage polarity is switched, the switch causes the load to change.
The AC adapter according to claim 1, wherein supply of a voltage output to the AC adapter is cut off . 3. A load current measuring unit for detecting the load current, and operating the polarity judging unit when a load is disconnected from the secondary connector based on a detection signal from the load current measuring unit. The AC adapter according to claim 1, further comprising a load connection state monitoring unit.