JPH06339232A - Charger - Google Patents

Abstract

PURPOSE:To effectively stop an oscillation of a power source of a primary side after full charging of a non-contact type charger. CONSTITUTION:When a storage battery B is fully charged, a high level signal is output from an output terminal of a charge control circuit PC, and transistors Q2, Q1 are turned ON. A voltage across a secondary coil LO is limited by the transistors Q2, Q1, and a voltage across a second coil LC is also limited. Accordingly, an energy of oscillation of an FET 3 is transmitted to a sensing coil L3 through a first coil L1. When a voltage across a sensing coil L3 exceeds the Zener voltage of a Zener diode ZD, a transistor Q10 is turned ON to stop oscillation of the FET 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is based on an electromagnetic induction method.
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 power supply unit and a load unit are separately configured, and a primary coil is provided on the power supply unit side and a secondary coil is provided on the load unit side having a storage battery. A charging device is used. When the built-in storage battery is charged by this charging device, the load part is attached to the power supply part. This conventional charging device will be described with reference to FIG. FIG. 8: is a circuit diagram which shows the load part side of the conventional charging device.

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

[0004]

However, in the above-mentioned conventional charging device, even when the full charge of the storage battery B is detected and the transistor QX1 is turned off, the electric power induced in the secondary coil L0 does not change. Therefore, while the load unit 21 is attached to the power supply unit, there is a problem that the power supply unit side continues to operate and generates heat and power loss.

The present invention solves the above problem, and detects the change in the state of the secondary side due to full charge of the storage battery in the power source section of the primary side, so that the power source section supplies power to the load section. An object is to provide a charging device that reliably performs transmission control.

[0006]

In order to achieve the above-mentioned object, the present invention provides a power supply section having a primary coil and a switching element which is controlled to oscillate and switches the power supply to the primary coil. In a power supply device that is detachable from a power supply unit and has a secondary coil and a storage battery that is 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 the output load of the secondary coil, and the power supply unit changes the load due to the control operation of the control unit to the primary coil via the secondary coil. It is provided with a detecting means for detecting from the voltage change appearing, and an oscillation stopping means for stopping the oscillation operation of the switching element when the detecting means detects the voltage change (claim 1).

Further, the primary coil comprises a first coil and a second coil which can be magnetically coupled to the secondary coil, which are connected in series, and the detecting means is magnetically coupled to the first coil. On the other hand, the control means includes a switch that short-circuits the secondary coil based on a full-charge detection signal, and through the first coil that occurs when the secondary coil is short-circuited. When the voltage change of the induced voltage of the detection coil induced by the above reaches a predetermined level, the oscillation stopping means is operated (claim 2).

[0008]

According to the invention described in claim 1, when the load part is attached to the power supply part, the electric 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. To be done. When the storage battery is fully charged, this is detected and the control means 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 means of the power supply section. When the detecting means detects this voltage change, the oscillating operation of the switching element is stopped, and the power transmission to the load section is stopped.

According to the second aspect of the invention, when the load section is attached to the power supply section, the electric 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. It 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 the voltage across the second coil is also limited. . Therefore, the electric power generated by the oscillation of the switching element is
It 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 which is an example of an electric device to which the present invention is applied. As shown in FIG. 2, the load unit 2 as a receiver is placed on the power supply unit 1 so that the load unit 2 having a built-in storage battery can be attached to the power supply unit 1. Thus, power transmission and its control are performed as described later.

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

An AC power source such as a commercial power source can be connected via a cord K between the input terminals. The AC power supply is rectified and smoothed by the rectifier diode BD and the capacitor C1 to obtain the DC power supply. This DC power supply includes a second coil LC and 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 composed of 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 composed of Q10 is connected.

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

The positive electrode of the DC power source and the feedback coil L2
A starting resistor R1 for starting the FET3 is connected between the capacitor C2 and the connection point of 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 the diode D0 and the smoothing capacitor C0. The emitter of the transistor Q1 is connected to the positive electrode of the storage battery B, the base is connected to the collector of the transistor Q2, and the collector is 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. 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 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 section showing the positional relationship between the first coil L1 and the second coil LC.
FIG. 3 is a schematic perspective view showing the mounting of the power supply unit 1 and the load unit 2 of the first embodiment.

Inside the power supply unit 1, a printed wiring board PB on which the above-mentioned circuit components are mounted is arranged. The first coil L1 and the first coil L1 are closely attached to 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 arranged apart from the printed wiring board PB in a state of being wound around a core on a projecting portion 12 provided substantially in the center of the upper surface of the frame 11 of the power supply unit 1. 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 arranged so as not to be magnetically coupled to each of these coils.

Further, as shown in FIG. 4, a concave portion 22 having a diameter slightly larger than the circumferential diameter of at least the protruding portion 12 is provided on the lower surface of the frame 21 of the load portion 2 and the inside of the frame 21 is provided. The secondary coil L0 is wound around the recess 22. Then, when the concave portion 22 of the load portion 2 is loosely fitted to the protruding 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 explained based on. FIG. 5 is a voltage waveform diagram of each part showing the operation of the first embodiment.

Connect the cord K of the power source unit 1 to an AC power source,
When the load unit 2 is attached to the power supply unit 1, the gate voltage is applied via the starting resistor R1 and the FET 3 starts to turn on. Then, the feedback coil L2 by the induced voltage of the first coil L1
FET3 is rapidly turned on by the induced voltage. And
When the source current of the FET3 increases and the voltage generated in the resistor R3 rises to a predetermined level, the transistor Q10 turns on, the gate voltage of the FET3 drops, and the FET3 turns off. In this way, 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 the charging is continued and the charging control circuit PC detects that the storage battery B is fully charged (see "charging 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 is turned 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 base-emitter voltage of the transistor Q1 is Vbe, and the collector-emitter saturation voltage 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, is substantially short-circuited, the secondary coil L0 is no longer oscillated thereafter (see “oscillation OFF” in FIG. 5). As a result, the second coil LC magnetically coupled to the secondary coil L0 also stops oscillating.

Therefore, 1 by switching the FET3
The oscillation on the next side is performed by the first coil L1 which is not magnetically coupled to the second coil LC. As a result, the first coil L1
Since the induced voltage of is higher than that during charging, the voltage induced in the detection coil L3 is also increased. This detection coil L
The generated smoothed voltage V3 obtained from No. 3 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, so that the transistor Q10 is turned on and the oscillation of the FET3 is stopped. 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 the off state, and the oscillation is stopped continuously.

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 parts as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the second embodiment, the diode D01 is connected to the circuit of the load unit 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 forward. Thus, the power supply unit 1 performs power transmission control different from that of the first embodiment.

Explaining the operation of the circuit of the second embodiment, the power supply unit 1 does not operate until the charge control circuit PC detects the full charge of the storage battery B and the oscillation of the FET 3 is stopped (“charge area” in FIG. 7). ~ "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 toward the positive electrode of the storage battery B, the transistor Q1
The voltage of the storage battery B is not applied to the emitter of 1. Therefore, when the oscillation of the FET3 is stopped, no electromotive force is generated in the second coil LC, that is, the secondary coil L0. Therefore, when the charge charged in 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.

Therefore, since the voltage across the secondary coil L0 is no longer limited, the energy on the primary side can be transmitted to the secondary coil L0 again via the second coil LC. Therefore, the transistor Q10 is turned off and the FET3
Oscillation is restarted. By restarting this oscillation, the voltage induced by the secondary coil L0, 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 this change to on causes the voltage change via the first coil L1 and the detection coil L3. Then, the oscillation of the FET 3 is stopped again. Then, such oscillation and its stop are repeated intermittently (“oscillation OFF”, “oscillation ON” in FIG. 7).
(Complementary 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 that supplies electric 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 changed through the secondary coil to the primary coil. The oscillation operation of the switching element is stopped by detecting the voltage change appearing on the power supply side, so that the oscillation operation of the power supply unit after the full charge can be surely stopped even though it is a non-contact type charging device. This eliminates problems such as heat generation and power loss.

[Brief description of 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 section 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]

 1 Power Supply Section 2 Load Section 3 Field Effect Transistor (FET) 11 and 21 Frame 12 Projection Section 22 Recessed Section B Storage Battery BD Rectifying Diode C0, C1, C2, C3 Capacitor D0, D01, D1, D2 Diode K Code L1 First Coil L2 Feedback coil L3 Detection coil LC Second coil L0 Secondary coil PC Charging control circuit P1 input terminal P2 output terminal Q1, Q2, Q10 Transistor R1, R2, R3, RX resistance ZD Zener diode

Claims (2)

[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 power supply unit detachably mountable to the secondary coil, and parallel to the secondary coil. In a power supply device comprising a load unit having a connected storage battery and transmitting electric power to the load unit by electromagnetic induction, the load unit detects the full charge of the storage battery and changes the output load of the secondary coil. The power source section detects 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 the detection means detects the voltage. A charging device, comprising: an oscillation stopping means for stopping the oscillation operation of the switching element when a change is detected. 2. The primary coil comprises a first coil and the second coil.
A second coil that can be magnetically coupled to the next coil is connected in series, and the detection means is a detection coil that is magnetically coupled to the first coil, while the control means is a full-charge detection signal. A switch for short-circuiting the secondary coil based on the above-mentioned, and a voltage change of the induced voltage of the detection coil induced through the first coil, which occurs with the short-circuiting of the secondary coil, reaches a predetermined level. 2. The charging device according to claim 1, wherein the oscillation stopping means is activated when reaching.