JP3247199B2 - Charging device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a charging device for a rechargeable electric device in which a secondary side and a secondary side are separated.

[0002]

2. Description of the Related Art Conventionally, a non-contact type non-contact type having a power supply unit and a load unit, a primary coil on a power supply unit side, and a secondary coil on a load unit side having a storage battery. A charging device is used. When charging the built-in storage battery with this charging device, the load unit is mounted on the power supply unit. This conventional charging device will be described with reference to FIG. FIG. 8 is a circuit diagram showing a load side of a conventional charging device.

The power induced in the secondary coil L0 on the load 21 by the primary coil on the power supply unit (not shown) is rectified by the diode D10 and smoothed by the capacitor C0. The low level signal is output from the output terminal P11 of the charge control circuit PC, the transistor QX1 is turned on, and the charge current is supplied to the storage battery B via the diode D11. Then, the input terminal P12 of the charge control circuit PC
Detects the full charge of the storage battery B, the output terminal P11
Output a high level signal to turn off the transistor QX1, thereby stopping the supply of the charging current.

[0004]

However, in the conventional charging device described above, even when the full charge of the storage battery B is detected and the transistor QX1 is turned off, the power induced in the secondary coil L0 does not change. Therefore, during the period in which the load unit 21 is mounted on the power supply unit, there is a problem that the state in which the power supply unit side operates continues to generate heat and power loss.

[0005] The present invention solves the above problem, and detects a state change on the secondary side due to a full charge of the storage battery by the power supply section on the primary side, so that the power supply section can supply power to the load section. An object of the present invention is to provide a charging device that reliably performs transmission control.

[0006]

In order to achieve the above object, the present invention provides a power supply unit having a primary coil and a switching element that is oscillated and switches power supply to the primary coil. In a power supply device that is detachable from a power supply unit and includes a load unit having a secondary coil and a storage battery connected in parallel to the secondary coil, and supplies power to the load unit by electromagnetic induction, the load unit includes: The power supply unit includes a control unit that detects a full charge of the storage battery and changes an output load of the secondary coil, and the power supply unit applies a change in load accompanying a control operation by the control unit to the primary coil via the secondary coil. A detecting means for detecting from the appearing voltage change, and an oscillation stopping means for stopping the oscillating operation of the switching element when the detecting means detects the voltage change (claim 1).

The primary coil includes a first coil and a second coil magnetically coupleable to the secondary coil connected in series, and the detecting means is magnetically coupled to the first coil. The control means comprises a switch for short-circuiting the secondary coil based on a full-charge detection signal, and the control means includes a switch for short-circuiting the secondary coil. When the voltage change of the induced voltage induced by the detection coil reaches a predetermined level, the oscillation stop means operates (claim 2).

[0008]

According to the first aspect of the invention, when the load section is mounted on the power supply section, the power generated by the oscillation of the switching element is transmitted from the primary coil to the secondary coil by electromagnetic induction, and the storage battery is charged. Is done. When the storage battery is fully charged, this is detected, and the control unit changes the output load of the secondary coil. The change in the load appears as a voltage change in the primary coil via the secondary coil, and this voltage change is detected by the detection unit of the power supply unit. When this voltage change is detected by the detecting means, the oscillation operation of the switching element is stopped, and the transmission of power to the load is stopped.

According to the second aspect of the present invention, when the load section is mounted on the power supply section, the power generated by the oscillation of the switching element is transmitted from the second coil to the secondary coil, and the storage battery is charged. You. When the storage battery is fully charged, the voltage across the secondary coil is limited to a low level, that is, both ends of the secondary coil are short-circuited or almost short-circuited, so that the voltage across the second coil is also limited. . Therefore, the power generated by the oscillation of the switching element
The signal is transmitted from the coil to the detection coil. Then, when the induced voltage of the detection coil rises and exceeds a predetermined level, the oscillation of the switching element is stopped.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the charging device according to the present invention will be described with reference to FIGS. FIG. 2 is a perspective view showing a cordless telephone as an example of an electric device to which the present invention is applied. The load unit 2 as a receiver is mounted on the power supply unit 1 as shown in FIG. 2, so that the load unit 2 having a built-in storage battery is mounted on the power supply unit 1. Thus, power transmission and its control are performed as described later.

Next, the circuit configuration of the power supply unit 1 and the load unit 2 will be described. FIG. 1 is a circuit diagram showing a first embodiment of the charging device according to the present invention.

An AC power supply such as a commercial power supply can be connected between input terminals via a cord K. The AC power is rectified and smoothed by the rectifier diode BD and the capacitor C1 to obtain a DC power. This DC power supply includes a second coil LC, a first coil L
1 and a field effect transistor (FET) 3 as a switching element are connected in series.

The FET3 has resistors R2 and R3 connected in series between its source and ground, a series oscillation circuit including a feedback coil L2 and a capacitor C2 connected between its gate and drain, and a diode D2 and a transistor between its gate and ground. A series circuit consisting of Q10 is connected.

The detecting coil L3 is connected to a rectifying diode D1 and a smoothing capacitor C3, and generates a smoothing voltage V3.
Is made to occur. Further, it is connected to a connection point between the resistors R2 and R3 via a Zener diode ZD and a resistor. The Zener diode ZD has a predetermined Zener voltage. That is, the Zener voltage is set to a value such that it does not turn on at the generated smoothed voltage V3 during charging but turns on at the generated smoothed voltage V3 generated after full charge, as described later. When the Zener diode ZD turns on, the transistor Q10
Is turned on to drop the gate of FET3 to ground.

Further, a positive electrode of a DC power supply and a feedback coil L2
An activation resistor R1 for activating the FET3 is connected between the connection point of the capacitor C2 and the capacitor C2.

The secondary coil L0 of the load section 2 is magnetically coupled to the second coil LC, and is further connected in parallel to the storage battery B via a diode D0 and a smoothing capacitor C0. The transistor Q1 has an emitter connected to the positive electrode of the storage battery B, a base connected to the collector of the transistor Q2, and a collector connected to the base of the transistor Q2. The emitter of the transistor Q2 is connected to the ground. Further, a base resistor RX is connected between the positive electrode of the storage battery B and the base of the transistor Q2.

The charge control circuit PC has an input terminal P1 connected to the positive electrode of the storage battery B in order to detect the voltage of the storage battery B, and detects the full charge of the storage battery B from the detected voltage. Further, the output terminal P2 is connected to the base of the transistor Q2, and outputs a low level signal until full charge is detected, and outputs a high level signal when the full charge of the storage battery B is detected.

Next, the positional relationship between the coils will be described with reference to FIGS. FIG. 3 is a partial cross-sectional view of the power supply unit showing the positional relationship between the first coil L1 and the second coil LC.
FIG. 2 is a schematic perspective view showing mounting of a power supply unit 1 and a load unit 2 according to the first embodiment.

Inside the power supply unit 1, a printed wiring board PB on which the above-described circuit components are mounted is disposed. The first coil L1 is in close contact with the printed wiring board PB.
A core around which the feedback coil L2 and the detection coil L3 are wound is arranged. On the other hand, the second coil LC is disposed in a state of being wound around the core at a protruding portion 12 provided substantially at the center of the upper surface of the frame 11 of the power supply unit 1, away from the printed wiring board PB. Thus, the first coil L1, the feedback coil L2, and the detection coil L3 are magnetically coupled to each other,
The second coil LC is disposed so as not to be magnetically coupled to each of these coils.

As shown in FIG. 4, a concave portion 22 having a diameter slightly larger than the peripheral diameter of the projecting portion 12 is provided on the lower surface of the frame 21 of the load portion 2. The secondary coil L0 is wound around the concave portion 22. Then, when the concave portion 22 of the load portion 2 is loosely fitted to the projecting portion 12 of the power supply portion 1 and the load portion 2 is mounted on the power supply portion 1,
The second coil LC and the secondary coil L0 are magnetically coupled.

Next, the operation of this circuit will be described with reference to FIGS.
It will be described based on. FIG. 5 is a voltage waveform diagram of each part showing the operation of the first embodiment.

The cord K of the power supply unit 1 is connected to an AC power supply,
When the load unit 2 is mounted on the power supply unit 1, a gate voltage is applied via the starting resistor R1, and the FET 3 starts to turn on. Then, the feedback coil L2 due to the induced voltage of the first coil L1
FET3 is rapidly turned on by the induced voltage. And
When the source current of FET3 increases and the voltage generated at resistor R3 rises to a predetermined level, transistor Q10 turns on, the gate voltage of FET3 drops, and FET3 turns off. Thus, the oscillation of the FET 3 is started. When the oscillating operation is started, a voltage is induced in the secondary coil L0 by the voltage generated in the second coil LC, and a charging current is supplied to the storage battery B via the diode D0 and the capacitor C0 ("Charging" in FIG. 5). Area ").

When charging is continued and the charge control circuit PC detects the full charge of the storage battery B (see "Charge completed" in FIG. 5), a high-level signal is output from the output terminal P2, and the transistor Q2 is turned on. Further, the transistor Q1 turns on, and the load state on the output side of the secondary coil L0 changes.
That is, the forward voltage of the diode D0 is Vd0, the voltage between the base and the emitter of the transistor Q1 is Vbe, and the saturation voltage between the collector and the emitter of the transistor Q2 is Vce (s
at), the voltage across the secondary coil L0 is Vd0 + Vb
Since it is limited by e + Vce (sat), that is, substantially short-circuited, the secondary coil L0 no longer oscillates (see "oscillation OFF" in FIG. 5). Thus, the second coil LC magnetically coupled to the secondary coil L0 also does not oscillate.

Therefore, 1 by switching of FET3
Oscillation on the secondary side is performed by the first coil L1 that is not magnetically coupled to the second coil LC. As a result, the first coil L1
Is higher than during charging, so the voltage induced by the detection coil L3 also increases. This detection coil L
3, the generated smoothed voltage V3 exceeds the sum of the Zener voltage of the Zener diode ZD and the generated voltage of the resistor connected to the anode side thereof, turning on the transistor Q10 and stopping the oscillation of the FET3. It becomes.

Since the battery voltage of the storage battery B is applied to the emitter of the transistor Q1 of the load section 2, the transistor Q1 is latched in an off state, whereby the oscillation is stopped.

Next, a second embodiment of the charging device according to the present invention will be described with reference to the circuit diagram of FIG. 6 and the voltage waveform diagram of FIG. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In the second embodiment, a diode D01 is connected to the circuit of the load section 2 of the first embodiment between the emitter of the transistor Q1 and the positive electrode of the storage battery B with the charging direction being the forward direction. Thus, the power supply unit 1 performs power transmission control different from that of the first embodiment.

The operation of the circuit of the second embodiment will be described. The power supply unit 1 operates until the charge control circuit PC detects the full charge of the storage battery B and the oscillation of the FET 3 stops (the "charge area" in FIG. 7). To “charging completed”), the same operation as in the first embodiment is performed. However, in the second embodiment, the diode D
01 is connected in the forward direction from the emitter of the transistor Q1 to the positive electrode of the storage battery B.
The voltage of the storage battery B is not applied to one of the emitters. Therefore, when the oscillation of the FET 3 stops, no electromotive force is generated in the second coil LC, that is, the secondary coil L0. Therefore, when the charge of the capacitor C0 is discharged, no voltage is applied to the emitter of the transistor Q1. As a result, the transistor Q1 is turned off.

Accordingly, the voltage at both ends of the secondary coil L0 is no longer limited, so that the energy on the primary side can be transmitted again to the secondary coil L0 via the second coil LC. Therefore, the transistor Q10 is turned off, and the FET3
Oscillation is restarted. Due to the restart of the oscillation, a voltage induced in the secondary coil L0 and rectified and smoothed by the diode D0 and the capacitor C0 is applied to the emitter of the transistor Q1. On the other hand, since the high level signal is continuously output from the output terminal P2 of the charge control circuit PC, the transistor Q1 is turned on, and the change to the on state is caused by the voltage change via the first coil L1 and the detection coil L3. And the oscillation of the FET 3 stops again. This oscillation and its stop are intermittently repeated (“oscillation OFF”, “oscillation ON” in FIG. 7).
(Auxiliary charging area) ”).

As described above, after the storage battery B is fully charged, the FE
Trickle charging can be performed by intermittently oscillating T3.

[0031]

As described above, according to the present invention,
In a power supply device for transmitting power from a main body to a load by electromagnetic induction, a full charge of a storage battery is detected to change an output load of a secondary coil, and this load change is converted to a primary coil through the secondary coil. Is detected on the power supply side from the voltage change appearing in the power supply, and the oscillation operation of the switching element is stopped, so that the oscillation operation of the power supply unit after full charge can be reliably stopped even though it is a non-contact charging device. This eliminates problems such as heat generation and power loss.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a charging device according to the present invention.

FIG. 2 is a perspective view showing an external appearance of an electric device to which the charging device according to the present invention is applied.

FIG. 3 is a partial cross-sectional view of a power supply unit showing a positional relationship between a first coil and a second coil.

FIG. 4 is a schematic perspective view showing mounting of a power supply unit and a load unit according to the first embodiment.

FIG. 5 is a voltage waveform diagram of each part showing the operation of the first embodiment.

FIG. 6 is a circuit diagram showing a second embodiment of the charging device according to the present invention.

FIG. 7 is a voltage waveform diagram of each part showing the operation of the second embodiment.

FIG. 8 is a circuit diagram showing a load section of a conventional charging device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power supply part 2 Load part 3 Field effect transistor (FET) 11, 21 Frame 12 Projection part 22 Concavity B Storage battery BD Rectifier diode C0, C1, C2, C3 Capacitor D0, D01, D1, D2 Diode K code L1 1st coil L2 Feedback coil L3 Detection coil LC Second coil L0 Secondary coil PC Charge control circuit P1 Input terminal P2 Output terminal Q1, Q2, Q10 Transistor R1, R2, R3, RX Resistance ZD Zener diode

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02J ^7/ 00-7/12 H02J ⁷ /34-7/36

Claims (2)

(57) [Claims] 1. A power supply unit having a primary coil and a switching element controlled to oscillate to switch power supply to the primary coil, a secondary coil detachable from the power supply unit, and parallel to the secondary coil. A load unit having a storage battery connected thereto and transmitting power to the load unit by electromagnetic induction, wherein the load unit detects a full charge of the storage battery and changes an output load of a secondary coil. Control means for detecting a change in load caused by a control operation by the control means from a voltage change appearing in the primary coil via the secondary coil; and A charging device, comprising: oscillation stop means for stopping an oscillation operation of the switching element when a change is detected. 2. The method according to claim 1, wherein the primary coil includes a first coil and the second coil.
A second coil magnetically coupleable to the next coil is connected in series, and the detecting means comprises a sensing coil magnetically coupled to the first coil, while the control means controls a full charge detection signal. A switch for short-circuiting the secondary coil on the basis of the above, and the voltage change of the induced voltage of the detection coil induced via the first coil, which is generated due to the short-circuit of the secondary coil, becomes a predetermined level. 2. The charging device according to claim 1, wherein said oscillation stopping means is operated when the charging time is reached.