JPS6362990B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a charging circuit for an electric shaver that can be used for both AC and DC functions.

Conventional AC/DC electric shavers require an external adapter for charging, which has the disadvantage of increasing the number of extra parts, and for this reason, so-called switchable electric shavers that do not require a charging adapter have been provided. That is, since the charging power is generally smaller than the power for driving the razor, when charging, the voltage is lowered by a resistor to reduce the charging current, and when driving the razor, the resistance is shorted to increase the output. However, this switching type has the disadvantage that loss due to resistance is large and heat generation adversely affects other electronic circuits.

In view of the above-mentioned points, it is an object of the present invention to provide a charging circuit for an electric shaver that not only allows charging without using an external adapter, but also eliminates loss due to resistance during charging.

The present invention will be explained in detail based on illustrated embodiments. In the present invention, a series circuit including a storage battery 6, a power switch 7, and a DC motor 5 for driving a razor is connected in parallel to the output end 4 of a transistor inverter 3 connected in parallel to a full-wave rectified power source 2 obtained by full-wave rectifying a commercial power source 1. Connect the preset reference voltage Vr and storage battery 6
Compare the voltage Vc across the
An inverter control circuit 8 is provided to reduce the output of the transistor inverter 3 when the output is higher than Vr,
The inverter control circuit 8 is controlled by an auxiliary switch 9 which is reversely interlocked so that the power switch 7 is turned off when the power switch 7 is on, and the operation of the inverter control circuit 8 is stopped when power is supplied to the DC motor 7. Each part will be explained in more detail below. The transistor inverter 3 includes inductors L ₁ , L ₂ , L ₃ wound around the same pulse transformer as the oscillation transistor Q ₃ , a backflow blocking diode D ₇ , and protection elements F ₅ , C ₂ , R ₈ , C ₁ and current limiting resistors R ₆ and R ₇ . Thus, when a full-wave rectified voltage is applied to the transistor inverter 3, a base current flows to the transistor _Q3 via the resistors _R6 , _R7 and the inductor _L3 , turning on the transistor _Q3 . And the collector current of transistor _Q3 is Ic=Vint/ _L1 (t is time, _L1 is the inductance of inductor _L1 ).
flows, and at this time, the transistor Q ₃ is further turned on due to the positive bias base voltage induced in the inductor L ₃ , and when the collector current Ic flows up to the maximum collector current Icp determined by hfe of the transistor Q ₃ , the current changes. disappears, the voltage across the inductor _L1 suddenly becomes reverse polarity, and this reverse polarity voltage is induced in the inductor _L3 , turning off the transistor _Q3 . And inductor L ₁
The energy stored in is induced in inductor _L2 and released to the outside via diode _D7 . After the energy is released, the voltage across the inductor L ₂ reverses its polarity, and the reversed voltage is induced in the inductor L ₃ to forward bias Q ₃ and turn on the transistor Q ₃ again. As described above, the transistor inverter 3 oscillates and releases energy to the outside from the inductor _L2 . Figure 2 shows the waveforms of each part mentioned above, where A is the collector-emitter voltage Vce of the transistor _Q3 , B is the collector current Ic of the transistor _Q3 , and C is the output current Io of the inductor _L2. It shows.

On the other hand, the inverter control circuit 8 includes a Zener diode _D1 that makes the full-wave rectified voltage a constant voltage, and a voltage dividing resistor that divides the voltage across the Zener diode _D1 .
R ₂ , R ₃ and diodes D ₂ , D ₃ , D ₄ , D ₅ , D ₆
, control transistors Q ₁ , Q ₂ , and current limiting resistor R ₂₀
and a relatively small voltage adjustment resistor R ₄ , and the voltage at the connection point of both voltage dividing resistors R ₂ and R ₃ is set as the reference voltage Vr. Therefore, if the auxiliary switch 9 is turned on, the reference voltage Vr
is compared with the voltage Vc across the storage battery 4 via the resistor R4, and when the voltage Vc across the storage battery ₄ is higher than the reference voltage Vr, the transistor _Q1 is turned off, the transistor _Q2 is turned on, and the base current of the transistor _Q3 is , and transistor _Q3 stops oscillating. Conversely, when the voltage Vc across the transistor is lower than the reference voltage Vr, the transistor _Q1 is turned on and absorbs the base current of the transistor _Q2 , so the transistor _Q2 is turned off and the transistor _Q3 continues to oscillate. In addition, when using a storage battery 6 with a low voltage Vc at both ends when fully charged, use a resistor.
By increasing the resistance value of R ₄ , the voltage drop across resistor R ₄
By increasing _VR , the inverter control circuit 8 can operate to control the operation of the transistor inverter 3 when the storage battery 6 is fully charged without changing the reference voltage Vr.

Charging of the storage battery 6 using the charging circuit configured as described above is performed as follows. That is, when the auxiliary switch 9 is turned on (of course, the power switch 7 is off), the storage battery 2 is charged by the output of the transistor inverter 3. As charging progresses and the voltage Vc across the storage battery 6 rises, the voltage Vc across the storage battery 6 becomes larger than the reference voltage Vr and the oscillation of the transistor Q ₃ stops. Therefore, charging current is not supplied to the storage battery 6, and the voltage Vc between both ends decreases due to natural discharge, and the transistor _Q3 oscillates again to supply charging current. That is, during charging, there are regions in which the full-wave rectified voltage does not oscillate, as shown in FIG. 3A, and the output current Io does not flow in these regions, as shown in FIG. 3B, so overcharging can be prevented. Next, when the power switch 7 is turned on, the auxiliary switch 9 is turned off and the inverter control circuit 8 is turned off.
The operation of is stopped and the output of the transistor inverter 3 is supplied to the DC motor 5. At this time, since the inverter control circuit 8 is stopped, the transistor _Q3 oscillates in almost the entire range of the full-wave rectified voltage as shown in Fig. 3C, and supplies the output current Io as shown in Fig. 3D to the DC power supply. That's what I do. Here, both ends of the full-wave rectified voltage do not oscillate due to insufficient voltage of transistor _Q3 .

Incidentally, in this embodiment, charging control is not performed during operation of the DC motor 5, and the reason for this is as follows.

In other words, if the load current of the DC motor 5 is I _L and the charging current is I ₀ , then when the load current of the DC motor 5 is smaller than the charging current such as I ₀ > I _L , the battery is charged even when the DC motor 5 is driven. Therefore, it is necessary to perform charging control, but when driving the DC motor 5 with the output from the transistor inverter 3, it is necessary to set I ₀ < I _L in response to the user's desire to shave forcefully and quickly. In this case, if charging is not completed, most of the output must flow into the DC motor 5, so charging control becomes unnecessary.

In particular, if there is a large difference (I _L > I ₀ ) between the charging current I ₀ , which is set based on the battery capacity used and the charging time, and the load current I _L of the DC motor 5 used, the battery capacity is exhausted. To sometimes increase the output to drive a load, the method shown in JP-A-54-129438 or setting the current to obtain the load current I _L and reducing the charging current I ₀ from there is a method. There is a problem in that a method is required, which leads to an increase in costs.

As a countermeasure to this problem, in the present invention, when driving a load, the inverter control circuit 8 is disconnected and charging control is not performed, and the output is set to a current that can drive the DC motor 5. On the other hand, when charging, the inverter control circuit 8 is activated and the charging control is not performed. This reduces the current I ₀ . In the embodiment, the resistance R ₄ of the inverter control circuit 8
The charging current I ₀ is reduced by appropriately setting the value of , and setting the outputs as shown in A and B in Fig. 3. When the battery voltage rises as the storage battery 6 charges, the inverter control circuit 8 detects this voltage and sets a longer period for stopping the operation of the transistor inverter 3, and as a result, the charging current I ₀
This prevents overcharging. If there is a large difference between the current I _L when driving the load and the charging current I ₀ in this way, it is not compensated for by the capacity of the transistor inverter 3, but the inverter control circuit 8 is used or not used to prevent overcharging and to switch the load drive. By doing this, the total cost can be reduced.

Furthermore, if the DC motor 5 is driven when the charging current I ₀ is limited in a fully charged state, the motor cannot be driven due to the insufficient output of the transistor inverter 3, and the shortage is compensated for by the storage battery 6. I have to make up for it. However, if this is done, there is a problem that the capacity of the fully charged storage battery 6 is reduced. However, in the present invention, since charging control is removed, the drive current for the DC motor 5 can be supplied from the transistor inverter 3.

FIG. 4 shows another embodiment, in which a transistor for overcurrent protection is shown.
Q ₄ and protection diodes D ₂₀ and D ₂₁ are added, and when an overcurrent flows through resistor R ₂₁ , transistor Q ₄ operates and stops oscillation of transistor Q ₃ .

Thus, in the present invention, a storage battery, a series circuit of a power switch, and a DC motor are each connected in parallel to a transistor inverter connected to a full-wave rectified power source, and when the voltage across the storage battery is higher than the reference voltage, the transistor inverter An inverter control circuit is provided to stop the operation of the DC motor, and an auxiliary switch that is reversely linked to the power switch stops the operation of the inverter control circuit when power is being supplied to the DC motor, so the storage battery is charged and the voltage at both ends increases. Since the transistor inverter stops operating when the voltage becomes higher than the reference voltage, the storage battery will not be overcharged, and when the voltage of the storage battery drops below the reference voltage due to natural discharge, the transistor inverter will stop operating. This has the effect of allowing supplementary charging. In addition, when the power switch is on, the auxiliary switch is turned off, and when the inverter control circuit is stopped, the transistor inverter supplies power to the DC motor without reducing the output, which is sufficient to supply power to the DC motor, which requires a large amount of power. By simply turning on and off the auxiliary switch to start and stop the inverter control circuit, it is possible to supply appropriate power to storage batteries and DC motors with different power consumption. Since there is no need to reduce power consumption due to heat consumption, there is no need to adversely affect other electronic circuits due to heat generation, and there is no need to use an external adapter, so there is no need to increase the number of parts. There is none. Furthermore, when driving a load, the inverter control circuit is disconnected and charging control is not performed, and the output is set to a current that can drive the DC motor, while when charging, the inverter control circuit is activated to reduce the charging current. Even if there is a large difference between the current when driving the load and the charging current, it is not compensated for by the capacity of the transistor inverter, but by preventing overcharging and switching the load drive by using or not using the inverter control circuit. The total cost can be reduced, and the DC motor can be driven without using battery capacity even in a fully charged state.

[Brief explanation of drawings]

Fig. 1 is a specific circuit diagram of one embodiment of the present invention, Fig. 2 A, B, and C are explanatory diagrams of the operation of the same transistor inverter; Figure 4 is a specific circuit diagram of another embodiment, in which 1 is a commercial power supply, 2 is a full-wave rectified power supply, 3 is a transistor inverter, 4 is an output terminal, 5 is a DC motor, 6 is a storage battery, and 7 is a power switch. , 8 is an inverter control circuit, 9 is an auxiliary switch, Vr is a reference voltage, and Vc is a voltage at both ends.

Claims (1)

[Claims] 1 A series circuit consisting of a storage battery, a power switch, and a DC motor for driving a razor is connected in parallel to the output terminal of a transistor inverter connected in parallel to a full-wave rectified power supply obtained by full-wave rectification of a commercial power supply, and a series circuit of a DC motor for driving a razor is connected in parallel to a preset reference voltage. The inverter control circuit is equipped with an inverter control circuit that compares the voltage across the storage battery and stops the operation of the transistor inverter when the voltage across the storage battery is higher than the reference voltage.The inverter control circuit uses an auxiliary switch that is reversely linked so that the power switch is turned off when the power switch is on. A charging circuit for an electric shaver, which controls the inverter control circuit and stops the operation of the inverter control circuit when power is supplied to the DC motor.