JP2880940B2 - Mobile phone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable telephone provided with a circuit for charging a battery.

[0002]

2. Description of the Related Art FIG.
This will be described with reference to the block diagram of FIG. The mobile phone 1 of FIG.
In A, the radio unit 18 forms an interface circuit for radio waves with a communication partner. The receiving circuit 19 and the transmitting circuit 20 form a voice interface circuit with the user.
The receiving circuit 19 includes a receiver amplifier and a receiver, and the transmitting circuit 20 includes a microphone amplifier and a microphone. A battery 15, which is a secondary battery such as a nickel-cadmium battery, generates a battery voltage Vb of about 4.8V. In this mobile phone 1A, the battery 15 is shown as being built in the main body, but the battery 15 may be mounted outside the main body. The DC / DC converter 16 serving as a power supply circuit converts the battery voltage Vb of the battery 15 into a predetermined voltage and supplies the voltage to the device control unit 17, the wireless unit 18, the receiving circuit 19, and the transmitting circuit 20. DC / DC converter 1
6 is activated by turning on a power switch (not shown). The device control unit 17A includes a microprocessor circuit (C
PU) as a main component, and controls a predetermined circuit among the above circuits to perform outgoing / incoming call control, call control, and various operation controls. The charging circuit 21 charges the battery 15 with electric power from the external power supply 3. FIG. 1 shows only connections related to power supply as to connections between the above circuits.

[0003] The plug 31 of the external power supply 3 is connected to the mobile phone 1A.
The charging circuit 21 connected to the jack 22 charges the battery 15 irrespective of whether the mobile phone 1A is talking or waiting. Therefore,
The DC / DC converter 16 is supplied with the power from the charging circuit 21 and the power from the battery 15 in a floating state. The charging circuit 21 performs pulse width modulation (P
This is a constant current supply circuit using the WM) method. The external power supply 3 has an AC / DC converter for converting 240V AC to 9V DC.
AC adapter with built-in DC converter, DC / DC to convert DC12V from car battery to DC9V
In general, battery voltage V such as power adapter with built-in converter
A dedicated power supply with an output voltage slightly higher than b is used.

[0004]

In the above-described conventional portable telephone, the pulse charging current generated by the charging circuit 21 is:
During a telephone call, the light is directly radiated to the telephone function unit including the device control unit 17A, the radio unit 18, the reception circuit 19, and the transmission circuit 20, or leaks into the telephone function unit by conduction through the DC / DC converter 16 to cause a call. In some cases, pulse noise was generated in the voice generated by the receiving circuit 19 or the voice signal generated by the transmitting circuit 20, and the voice quality was sometimes deteriorated.

Further, since the external power supply 3 needs a peak current capacity larger than the specified average charging current of the charging circuit 21, there is a great restriction on the selection such as the need to use a dedicated power supply as the external power supply 3. Was.

[0006]

SUMMARY OF THE INVENTION A portable telephone according to the present invention comprises a radio section serving as an interface circuit for radio waves with a communication partner, a receiving circuit and a transmitting circuit serving as a voice interface circuit with a user, and a battery. A secondary battery that generates a voltage, a power supply circuit that converts the battery voltage to a predetermined voltage and supplies the voltage to a predetermined circuit in the device, and a power supply from an external power supply to a first external power supply terminal or a second external power supply A portable device including a charging circuit of a pulse width modulation system for receiving the terminal and charging the secondary battery, and a device control unit for controlling a predetermined circuit in the device to perform transmission / reception control, call control, and various operation controls. The telephone further includes a charge control circuit that controls the charging circuit to stop charging the secondary battery when receiving a busy signal from the device control unit, wherein the charge control circuit is If it is not receiving a signal during a call and it is detected that the power from the external power supply is being received at the first external power supply terminal, the charging current of the charging circuit is set to a first current value. Setting, and detecting that the power supply from the external power supply is being received by the second external power supply terminal without receiving the busy signal, the charging current of the charging circuit is A second current value lower than the first current value, wherein each of the first and second external power supply terminals has a switch for detecting insertion of a plug from the external power supply; The charge control circuit
By detecting plug insertion due to the switching of the switch, it is determined which of the first and second external power supply terminals is receiving power from the external power supply.

[0007]

[0008]

[0009]

Next, the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a portable telephone according to an embodiment of the present invention. FIG. 2 is a waveform diagram of output current Ic of charging circuit 14 in the present embodiment.

The portable telephone 1 is a portable telephone 1 shown in FIG.
Battery 15, DC having the same configuration, function and connection as A
A DC / DC converter 16, a radio section 18, a receiving circuit 19 and a transmitting circuit 20 are provided. Device control unit 1 of mobile phone 1
Reference numeral 7 has a function of transmitting a busy signal S3 to the charging control circuit 13 when the mobile phone 1 is busy, in addition to the function of the device control unit 17A of FIG. While the mobile phone 1 is waiting, the device control unit 17 stops transmitting the busy signal S3. The PWM charging circuit 14 charges the battery 15 with the power from the external power supply 3. However, the charging circuit 14 can set two kinds of charging currents, rapid charging and low current charging, for the battery 15 by controlling the switch signal S4 generated by the charging control circuit 13, and the charging of the battery 15 is turned on.・ It is turned off.

Hereinafter, the operation of charging the battery 15 will be described in detail. The jack switch 11 is an external power supply terminal for quick charging, and the jack switch 12 is an external power supply terminal for low current charging. The rapid charging is, for example, a case where the battery 15 is charged with an average current of 350 mA, and the low-current charging is, for example, a case where the battery 15 is charged with an average current of 100 mA. For example, the peak current capacity of the external power supply 3 is 700
If it is about mA, the plug 31 which is a power supply terminal of the external power supply 3 is inserted into the jack switch 11, and if the peak current capacity is about 200mA, the plug 31 is inserted into the jack switch 12. Jack switches 11 and 12
In both cases, when the plug 31 is inserted, the input terminal is switched to connect the plug 31 to the common terminal. These common terminals are connected to a resistor Ra which is a power input terminal of a charging circuit 14 for quick charging in the case of the jack switch 11, and are connected to a power input terminal of the charging circuit 14 for low current charging in the case of the jack switch 12. It is connected to a certain resistor Rb. The terminals of the jack switches 11 and 12 connected to the plug 31 are connected to the charging control circuit 13. When the plug 31 is inserted, the jack switch 11
Insertion detection signal S1, that is, output voltage Ve of external power supply 3
To the charge control circuit 13, and the jack switch 12 sends a detection signal S 2 of the insertion of the plug 31 to the charge control circuit 13.

The charging circuit 14 receives the current I from the external power supply 3
a current limiting circuit for limiting c, a switch circuit for switching the current Ic, and a switch width control circuit for controlling the switch width W of the current Ic passing through the switch circuit in accordance with the switch signal S4 from the charge control circuit 13. The charging circuit 14 sets the peak charging current Id to a first current value, for example, 700 mA when receiving power supply from the jack switch 11, and sets the peak charging current Id to the first current value when receiving power supply from the jack switch 12. It is set to a second current value lower than the value, for example, 200 mA. However, during the telephone call of the mobile phone 1, the charging control circuit 13 receives the busy signal S3 and does not generate the switch signal S4, and the switch circuit blocks passage of the current Ic. No current Id is generated. That is, the charging circuit 14 does not charge the battery 15 during a call of the mobile phone 1. Therefore, during a call, circuits related to the call, such as the reception circuit 19 and the transmission circuit 20, do not receive the pulse noise generated by the charging circuit 14,
The communication quality of the mobile phone 1 can be kept good.

On the other hand, when the portable telephone 1 is on standby, the charging control circuit 13 does not receive the busy signal S3, and therefore generates a switch signal S4 having a period T and a switch width W. When the charging control circuit 13 detects that the power from the external power supply 3 has been received by the jack switch 11 by receiving the detection signal S1, the charging control circuit 13 changes the average charging current Im to the battery 15 to a first current value Imr, for example, 350 mA. Set to. That is, the charge control circuit 13 determines that Imr = Id · Wr / T, that is, Wr
Switch signal S with a duty such that /T=0.5
4 to the charging circuit 14. The average charging current Imr can be changed by appropriately setting the duty.
The charging circuit 14 rapidly charges the battery 15 with the current Ic having the same waveform as the received switch signal S4.

The charge control circuit 13 detects the detection signal S2
Receiving the power from the external power supply 3 to the jack switch 12, the average charging current Im to the battery 15 is changed to a second current value Ims, for example, 100
Set to mA. That is, the charge control circuit 13 determines that Ims = I
The switch signal S4 having a duty such that d · Ws / T, that is, Ws / T = 0.5 is sent to the charging circuit 14. The charging circuit 14 charges the battery 15 at a low current with the current Ic having the same waveform as the received switch signal S4. As described above, since the mobile phone 1 has the two modes of the quick charge and the low current charge, there is an effect that the battery 15 can be charged using various external power sources 3.

The charging circuit 13 will be described in detail. The resistors Ra and Ra constitute a current limiting circuit, and the resistor R
1, the diode D1 and the FET transistor Q1 form a switch circuit, and the resistors R2 and R3 and the NPN transistor Q2 form a switch width control circuit. The switching circuit is connected between the common terminal of the jack switch 11 via the resistor Ra and the anode of the diode D1 for backflow prevention, and connected between the common terminal of the jack switch 12 and the anode of the diode D1 via the resistor Rb. Connect to The cathode of the diode D1 is connected to the drain of the transistor Q1, and the drain and gate of the transistor Q1 are connected to each other.
4 is a charging current output terminal. The resistor R1 is connected between the gate and the drain of the transistor Q1.

In the switching width control circuit of the charging circuit 14, the base of the transistor Q2 receives the switching signal S4 via the resistor R2. The collector of transistor Q2 is connected to the gate of transistor Q1, and the emitter is connected to ground potential. Resistor R3 is transistor Q
2 between the base and the emitter. When a positive-level switching signal S4 is applied to the resistor R2, the transistor Q2 is turned on, and the transistor Q1 is turned on.
Gate changes to the on level. As a result, the transistor Q1 is turned on to generate the charging current Ic (Id).

When the output voltage of the external power supply 3 is Ve, the ON voltage of the diode D1 is Vd, the ON voltage of the transistor Q1 is Vq, and the voltage of the battery 15 is Vb, the resistance value of the resistor Ra is RA. , Average charging current Imr = {(Ve−Vq−Vb) · Wr} / (T
RA). When the resistance value of the resistor Rb is RB, the average charging current Ims = ｛(V
e−Vq−Vb) · Ws / (T · RB). Therefore, the resistors RA and RB of the resistors Ra and Rb are:
The battery voltage Vb of the battery 15 is a fixed value of about 4.8 V,
If it is determined that the external power supply 3 has a voltage Ve of about 9 V, it can be determined according to the value of the average charging current Im.

FIG. 3 is a flowchart of the operation of charging battery 15 in the present embodiment. Hereinafter, the charging operation of the battery 15 in the mobile phone 1 will be described with reference to FIGS.

When the plug 31 of the external power supply 3 is inserted into the jack switch, for example, the jack switch 11 while the power switch of the portable telephone 1 is turned on, and the external power supply 3 is activated, the charging control circuit 13 switches the jack switch 11 from the jack switch 11. A detection signal S1 for quick charging is received (step 1). At this time, the device control unit 17 determines whether the mobile phone 1 is in a call, that is, in a state of transmitting radio waves from the wireless unit 18 or in a standby state. The circuit 13 receives the busy signal S3 from the device control unit 17 (step 2). When receiving the busy signal S3 (Y in step 2), the charging control circuit 13 stops transmitting the switch signal S4 and stops the battery 1
5 is stopped (step 4). Step 2
When the charging control circuit 13 does not receive the busy signal S3 (N in step 2), the charging control circuit 13 sends out the switch signal S4 to cause the charging circuit 14 to
5 is started (step 3). Thereafter, when a call state is entered (Y in step 2), the flow proceeds to step 4.
And the charging of the battery 15 is stopped.

In this embodiment, the value of the charging current Im is set to Imr for quick charging and Ims for low current charging.
However, these types of charging current Im increase the number of jack switches and increase the charging current Ic.
It is needless to say that more than two types can be achieved by using the same technology as in the present embodiment, such as providing a large number of limit values.

[0022]

As described above, according to the present invention, the charging control circuit controls the PWM type charging circuit to stop the charging of the secondary battery during a telephone call of a mobile phone. There is an effect that the circuit does not generate pulse noise, so that voice quality with low noise and high intelligibility can be obtained.

In the present invention, the charging control circuit and the charging circuit include a mode in which the secondary battery is charged with a low current and a mode in which the secondary battery is rapidly charged with a large current. There is an effect that a simple power supply can be used.

[Brief description of the drawings]

FIG. 1 is a block diagram of a mobile phone according to an embodiment of the present invention.

FIG. 2 is a waveform diagram of an output current Ic of a charging circuit 14 in the present embodiment.

FIG. 3 is a flowchart of an operation of charging battery 15 in the present embodiment.

FIG. 4 is a block diagram of a mobile phone according to the related art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mobile telephone 3 External power supply 11, 12 Jack switch 13 Charging control device 14 Charging circuit 15 Battery 16 DC / DC converter 17 Device control unit 18 Radio unit 19 Receiving circuit 20 Transmission circuit 31 Plug D1 Diode Q1, Q2 Transistors R1 to R3 , Ra, Rb resistor

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-56574 (JP, A) JP-A-9-130456 (JP, A) JP-A-1-279640 (JP, A) JP-A-2- 146937 (JP, A) JP-A-2-155439 (JP, A) JP-A-2-13339 (JP, U) JP-A-60-93454 (JP, U) JP-A-1-105236 (JP, U) 60-192630 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04M 1/00 H02J 7/00 301 H02J 7/34

Claims (1)

(57) [Claims] 1. A radio unit serving as an interface circuit of a radio wave with a communication partner, a receiving circuit and a transmitting circuit serving as a voice interface circuit with a user, a secondary battery generating a battery voltage, and the battery voltage And a power supply circuit for converting the power from the external power supply into a first external power supply terminal or a second external power supply terminal.
A portable device comprising: a pulse width modulation type charging circuit for receiving the secondary battery to charge the secondary battery; and a device control unit for controlling a predetermined circuit in the device to perform outgoing / incoming control, call control, and various operation controls. The telephone, further comprising: a charge control circuit that controls the charging circuit to stop charging the secondary battery when receiving a busy signal from the device control unit, wherein the charge control circuit is configured to control the busy signal. Receiving the power from the external power supply to the first external power supply terminal, and setting the charging current of the charging circuit to a first current value; Further, when it is not receiving the call-in-progress signal and it is detected that the power from the external power supply is being received by the second external power supply terminal, the charging current of the charging circuit is changed to the first current. No. lower than the current value Wherein each of the first and second external power supply terminals has a switch for detecting insertion of a plug from the external power supply, and the charge control circuit switches the switch. A mobile phone that determines which of the first and second external power supply terminals is receiving power from the external power supply by detecting plug insertion by the external power supply.