JP2010062694A - Mobile terminal, and mobile terminal device with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To interconnect a charging cradle with a mobile terminal using the minimum number of terminals and the minimum number of poles. <P>SOLUTION: In a mobile terminal device 1, when the mobile terminal 10 is mounted in the charging cradle 30, a feeding terminal 31 and a power receiving terminal 13 are connected. Then, a switch 17 is turned off to stop power supply from a secondary battery 11 to a load 12, and power supply is performed to the load 12 only from the power receiving terminal 13. When the mobile terminal 10 is removed from the charging cradle 30, the switch 17 is turned on to supply the power from the secondary battery 11 to the load 12. In such a case, a diode 18 for preventing voltage from being applied to the power receiving terminal 13 is arranged in a circuit 21 for connecting the power receiving terminal 13 and the load 12. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a portable terminal that can be used, particularly a portable terminal that can be used close to a user's face, such as a wireless indoor parent unit, a wireless telephone cordless handset, and a portable telephone of an interphone, and a portable terminal device that includes the portable terminal.

  In general, a mobile terminal in a mobile terminal device always supplies power from a secondary battery to various circuits that are loads in the mobile terminal, regardless of whether or not the battery is attached to or detached from the charging stand. And since a portable terminal maintains a state, electric power more than predetermined amount is always needed. Therefore, since the portable terminal in this portable terminal device always supplies power from the secondary battery to the load, charging and discharging are repeated even while the portable terminal is mounted on the charging stand. As a result, the number of times the secondary battery repeats charging and discharging increases, resulting in a reduction in the life of the secondary battery.

  Patent Document 1 describes a portable terminal device having a portable terminal having a nickel-cadmium battery, which is a secondary battery, and a charging base connected to an external power source and detachable from the portable terminal. The portable terminal in this portable terminal device cuts off power supply from the nickel cadmium battery to various circuits that are loads in the portable terminal by being mounted on the charging stand. On the other hand, various circuits as loads in the portable terminal are connected to an external power source via a three-terminal plug or a predetermined terminal for power supply.

  Patent Document 2 discloses a portable terminal device in which a portable terminal having a secondary battery is connected to an external power source, and a portable terminal and a detachable charging stand are connected via a power supply terminal and a charging terminal. Are listed. In this portable terminal device, when the portable terminal is mounted on the charging stand, power is supplied from the external power source to the secondary battery via the charging terminal, and the secondary battery is charged. In addition, the portable terminal device is provided with switching means for switching the power supply target to various circuits. When the portable terminal is mounted on the charging stand, the portable terminal device is directly connected to various circuits via the power supply terminal. When power is supplied and the portable terminal is removed from the charging stand, power is supplied from the secondary battery to various circuits.

Japanese Patent No. 2773180 (FIG. 1) Japanese Patent No. 3191692 (FIG. 1)

  However, in the portable terminal device described in Patent Documents 1 and 2 described above, as a terminal for connecting the charging base and the portable terminal, a charging terminal and a terminal for supplying power to the load of the portable terminal are required separately, and the number of terminals is large. As the number increases, a charging terminal having a two-terminal structure dedicated to charging, which is widely used in general, cannot be used.

  Therefore, an object of the present invention is to provide a portable terminal that can be connected to a charging stand with simple terminals or a small number of terminals, and a portable terminal device including the portable terminal.

Means for Solving the Problems and Effects of the Invention

  The portable terminal of the present invention is a portable terminal that is detachable from a charging stand connected to an external power source, and receives power connected to a power feeding terminal of the charging stand when the portable terminal is attached to the charging stand. A terminal, a chargeable / dischargeable secondary battery, a load, a first circuit that connects the power receiving terminal and the secondary battery, a second circuit that connects the power receiving terminal and the load, and the secondary A third circuit for connecting the battery and the load; a switching means provided in the third circuit for switching a connection state between the secondary battery and the load; and detecting a voltage of the power receiving terminal; When the terminal is mounted on the charging stand, the secondary battery and the load are disconnected, the power supply from the secondary battery to the load is stopped, and the portable terminal is removed from the charging stand. When the secondary battery and the load are conducted, Switching control means for controlling the switching means so as to supply power from the secondary battery to the load; and first backflow prevention means provided in the second circuit for preventing current from flowing toward the power receiving terminal. And.

  According to the portable terminal of the present invention, only the two-pole power receiving terminals necessary for charging are connected to the charging stand, and the number of terminals can be reduced and the configuration can be simplified. Further, since the mobile terminal directly supplies power to the load from the external power source without going through the secondary battery when mounted on the charging stand, unnecessary discharge of the secondary battery can be suppressed and the life can be extended. In addition, if the 1st backflow prevention means is not arrange | positioned in the 2nd circuit, when a portable terminal is removed from a charging stand, the predetermined voltage based on a secondary battery will be via a load of a 3rd circuit or a portable terminal. It will occur at the power receiving terminal. Therefore, the first backflow prevention means provided in the second circuit for preventing the current from flowing toward the power receiving terminal is configured such that when the portable terminal is removed from the charging stand, the secondary battery is connected to the power receiving terminal. In order to prevent the voltage from returning, the switching means is switched based on the detection that the predetermined voltage does not exist at the power receiving terminal, and power is supplied from the secondary battery to the load of the portable terminal via the third circuit. To do. This also has the effect of preventing a failure or accident due to a short circuit of the power receiving terminal.

  The charging circuit further includes a charging circuit that is provided in the first circuit and controls a charging current to the secondary battery, and the charging circuit limits a charging current from the external power source to the secondary battery. It is preferable. When an external power supply supplies power to the load and the secondary battery at the same time, how much current flows in which depends on the size of the load and the charging current value required for the secondary battery. When the current flowing from the external power source to the load is small and the charging current to the secondary battery is large, the driving of the mobile terminal is stopped. Thus, by appropriately limiting the current from the external power supply to the secondary battery, it is possible to reliably supply power to the load. In addition, it is possible to prevent an unnecessary charging current from flowing to the secondary battery and suppress the heat generation phenomenon of the secondary battery. Furthermore, when the external power source is an AC power source, the AC adapter provided between the external power source and the charging stand can be made cheaper, and the cost can be reduced.

  Moreover, it is preferable that the said charging circuit performs only one charge when the said portable terminal is mounted | worn with the said charging stand. According to this, only one charging operation is performed when the battery is mounted on the charging stand, and the life of the secondary battery can be further extended by limiting to one charging / discharging cycle during mounting on the charging stand.

  Furthermore, it is preferable that a temperature sensor for detecting the ambient temperature is provided, and charging of the secondary battery is stopped when an outside air temperature not suitable for the secondary battery is detected.

  Further, the switching means is preferably a MOS transistor.

  In addition, it is preferable that the second backflow prevention means is arranged in series with the MOS transistor. If the switching means is a MOS transistor with a built-in noise prevention diode in particular, current flows into the secondary battery via the diode when the MOS transistor is OFF. Therefore, backflow can be prevented by arranging the second backflow prevention means.

  The portable terminal device of the present invention includes any one of the portable terminals described above and a charging base that is connected to the external power source and is detachable from the portable terminal.

  According to the portable terminal device of the present invention, the life of the secondary battery can be extended. In addition, it is possible to provide a portable terminal that can be connected to the charging stand with simple terminals or a small number of terminals, and a portable terminal device including the portable terminal.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an electrical block diagram of the mobile terminal device according to the present embodiment. In FIG. 1, only the plus signal line is shown, and the minus signal line, that is, the signal line connected to the ground is not shown. FIG. 2 is a circuit diagram of a part of the mobile terminal device according to the present embodiment. The portable terminal device according to the present embodiment is installed indoors, and can charge a portable terminal such as a wireless interphone master unit used for a call with an entrance cordless handset, a wireless phone cordless handset, or a cellular phone, and the portable terminal. A simple charging device.

  As shown in FIG. 1, the mobile terminal device 1 includes a portable terminal 10 that can be carried, and a charging stand 30 that is connected to an AC power source 32 (external power source) such as a commercial power source via an AC adapter 33. Yes.

  The AC adapter 33 is a power supply device that converts AC power supplied from the AC power supply 32 into DC power and supplies it to the charging stand. The charging stand 30 outputs the DC power supplied from the AC adapter 33 from the power supply terminal 31.

  As shown in FIGS. 1 and 2, the mobile terminal 10 includes a secondary battery 11, a load 12, a power receiving terminal 13, a charging circuit 14, an MPU 15, and a power supply switching control unit 40. The load 12 is a general term for various circuits and elements to which power is supplied in the mobile terminal 10.

  The power receiving terminal 13 can be connected to the power feeding terminal 31 when the mobile terminal 10 is mounted on the charging stand 30. The power receiving terminal 13 is connected to the secondary battery 11 via a power supply switching control unit 40, a circuit 20 (first circuit) in which the charging circuit 14 is arranged, and a common circuit 23. In addition, the power receiving terminal 13 is connected to the load 12 via a power source switching control unit 40, a circuit 21 (second circuit) in which a diode 18 (first backflow prevention means) is disposed, and a common circuit 24. The diode 18 has an anode on the power receiving terminal 13 side and a cathode on the load 12 side.

  The secondary battery 11 is connected to the load 12 via a circuit 22 (third circuit) in which a diode 19 (second backflow prevention means) and a switch 17 (switching means) are arranged on the way, and common circuits 23 and 24. Yes. The diode 19 has an anode on the secondary battery 11 side and a cathode on the load 12 side. In addition, the secondary battery 11 can be charged with DC power supplied from the power receiving terminal 13 and can supply power by discharging the load 12. The common circuit 23 corresponds to the first circuit and the third circuit in the present invention, and the common circuit 24 corresponds to the second circuit and the third circuit in the present invention.

  The charging circuit 14 controls the charging current to the secondary battery 11 according to the charging state of the secondary battery 11. The MPU 15 is a microprocessor (Micro Processing Unit) that performs arithmetic processing, and monitors the ON / OFF of the charging circuit 14. As an example of the monitoring, a thermistor 50 (see FIG. 2), which is a temperature sensor, is externally attached to the MPU 15. When the thermistor 50 detects that the battery temperature is not suitable for the charging temperature, the MPU 15 sends a charging start / stop signal to the charging circuit 14 so that charging is not forcibly performed.

  The switch 17 is a MOS transistor, and is turned on when no voltage is applied to the gate (that is, 0 V), and the circuit 21 makes the secondary battery 11 and the load 12 conductive. Further, the switch 17 is turned OFF when a voltage is applied to the gate, and the circuit 21 cuts off the secondary battery 11 and the load 12.

  The power supply switching control unit 40 controls the ON / OFF operation of the switch 17 depending on whether or not the mobile terminal 10 is mounted on the charging stand 30. In the present embodiment, the power supply switching control unit 40 divides the voltage value supplied from the power receiving terminal 13 by a resistor and applies it to the switch 17. Specifically, the power supply switching control unit 40 turns on the switch 17 by applying 0 V from the power receiving terminal 13 when the mobile terminal 10 is detached from the charging stand 30. In addition, when the mobile terminal 10 is mounted on the charging stand 30, the power supply switching control unit 40 turns off the switch 17 by applying the voltage value supplied from the power receiving terminal 13 by dividing it with a resistor. It should be noted that the capacitance values of the capacitor 61 of the circuit 21 and the capacitor 62 of the common circuit 24 of the circuit 20 and the circuit 22 are optimized in order to smoothly switch the ON / OFF of the switch 17 and to perform the current supply to the load 12 without interruption. It has become.

  The diodes 18 and 19 are elements having a rectifying action, and flow current only from the anode to the cathode. That is, in the circuit 21, current flows only from the power receiving terminal 13 toward the load 12. In the circuit 22, current flows only from the secondary battery 11 toward the load 12.

  Next, the case where the portable terminal 10 is attached to the charging stand 30 and the case where it is detached from the charging stand 30 will be described.

  First, when the mobile terminal 10 is mounted on the charging stand 30, a voltage is applied to the power receiving terminal 13, so that the power supply switching control unit 40 turns off the switch 17. Then, the secondary battery 11 and the load 12 are disconnected in the circuit 22, and power is not supplied from the secondary battery 11 to the load 12. The power supplied from the power receiving terminal 13 is supplied to the load 12 via the circuit 21. The power supplied from the power receiving terminal 13 is also supplied to the secondary battery 11 via the charging circuit 14. At this time, the current supplied to the secondary battery 11 is reduced by limiting the current flowing through the secondary battery 11 by the charging circuit 14.

  The secondary battery 11 is discharged by the supply of electric power from the secondary battery 11 to the load 12 when a discharge current flows, mainly when the portable terminal 10 is detached from the charging stand 30, and the battery voltage decreases. The charging circuit 11 starts charging from an arbitrary discharge state when the mobile terminal 10 is placed on the charging stand 30. The charging current during charging is limited so as not to exceed a certain current value, and charging is terminated under a fully charged condition. In the recent secondary battery function, spontaneous discharge is almost zero, and when the mobile terminal 10 is placed on the charging stand 30, only one charge is performed, and once it reaches a fully charged state, the charging operation is performed. Even if it is not performed, a proper charge state can be maintained for a considerably long time. That is, in this example, the charging / discharging cycle of the secondary battery is only one charging operation every time the mobile terminal 10 is placed on the charging stand 30, and the number of charging / discharging cycles is greatly reduced. This can contribute to extending the life of the secondary battery 11.

  Note that the charging current value of the secondary battery 11 is limited so as not to exceed a certain current value as described above, and as a result, the secondary battery 11 cannot be rapidly charged. An unnecessary charging current can be prevented from flowing, and problems such as heat generation of the secondary battery can be avoided. In addition, even if the AC adapter has a relatively small capacity, when the portable terminal 10 is attached to the charging stand 30 and installed, the load 12 of the portable terminal 10 has at least a waiting function and a function display. A sufficient current value can be secured.

  Especially when the mobile terminal is a wireless intercom base unit that is installed indoors and is used for calls with the entrance unit, it is used less frequently even if the charging current to the secondary battery is limited. In many cases, the process is completed in a short time, so that it can be used almost without any problem in actual use.

  The MPU 15 monitors the charging state of the secondary battery 11 and inputs a charging end signal from the charging circuit 14. The MPU 15 measures the outside air temperature of the portable terminal 10 by using a temperature sensor 50 of an externally attached thermistor. When the portable terminal 10 is attached to the charging base 30, the temperature sensor 50 detects that the portable terminal 10 has been attached to the charging base 30 by supplying power from the outside and generating a voltage at the sensor terminal. In order to charge the secondary battery 11, a charging start signal is output from the MPU 15 to the charging circuit 14. At this time, when the temperature sensor 50 detects that the outside air temperature is not preferable for the secondary battery, for example, other than 0 ° C. to 40 ° C., the temperature sensor 50 outputs a charge stop signal to the charging circuit 14. When the charging circuit 14 receives the charging stop signal, the charging circuit 14 does not start charging the secondary battery 11 on the assumption that the temperature is not preferable for the secondary battery.

  In this embodiment, since the switch 17 is a MOS transistor having a built-in noise prevention diode in particular, a minute reverse current flows when the switch is OFF, and a current flows toward the secondary battery 11. End up. Therefore, by arranging the diode 19, it is possible to prevent the current from flowing back to the secondary battery 11. Further, leakage current from the charging circuit 14 to the power receiving terminal 13 is prevented by the characteristics of the charging circuit 14 itself.

  Next, when the portable terminal 10 is removed from the charging stand 30, no voltage is applied to the power receiving terminal 13 (that is, 0 V), so the switch 17 is turned on by the power supply switching control unit 40. Then, in the circuit 22, the secondary battery 11 and the load 12 are brought into conduction, and power is supplied from the secondary battery 11 to the load 12.

  At this time, if the diode 18 is not arranged in the circuit 21, the voltage of the secondary battery 11 is applied to the power receiving terminal 13 through the circuit 21. A diode 18 provided in the circuit 22 for preventing a current from flowing toward the power receiving terminal 13 prevents the voltage of the secondary battery 11 from returning to the power receiving terminal 13 when the portable terminal is removed from the charging base. Then, the output voltage of the power supply switching control circuit 40 is set to 0 V, the switch 17 is turned on, and power is supplied from the secondary battery 11 to the load 20 of the portable terminal via the circuit 22. This also prevents failure or accidents inside the portable terminal due to a short circuit of the power receiving terminal 13.

  According to the portable terminal device 1 described above, only the two power receiving terminals 13 are connected to the power feeding terminal 31 of the charging stand 30, and the number of terminals and the number of poles can be reduced.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. For example, in the present embodiment, the switch 17 is a MOS transistor, but is not limited thereto, and may be a bipolar transistor or a relay.

  Further, if the switch 17 does not have a characteristic of flowing a reverse current, the diode 19 may not be provided.

  Further, one end of the circuit 20 and one end of the circuit 23 may be directly connected to the secondary battery 11 without being connected to the secondary battery 11 via the common circuit 23. Further, one end of the circuit 21 and the other end of the circuit 23 may be directly connected to the load 12 without being connected to the load 12 via the common circuit 24.

It is an electrical block diagram of the portable terminal device which concerns on this embodiment. It is a partial circuit diagram of the portable terminal device concerning this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Portable terminal device 10 Portable terminal 11 Secondary battery 12 Load 13 Power receiving terminal 14 Charging circuit 17 Switch 18, 19 Diode 30 Charging stand 31 Feeding terminal 32 AC power supply

Claims (7)

A portable terminal that can be detached from a charging stand connected to an external power source,
When the portable terminal is mounted on the charging stand, a power receiving terminal connected to a power feeding terminal of the charging stand;
A rechargeable secondary battery;
Load,
A first circuit connecting the power receiving terminal and the secondary battery;
A second circuit connecting the power receiving terminal and the load;
A third circuit connecting the secondary battery and the load;
Switching means provided in the third circuit, for switching a connection state between the secondary battery and the load;
When the voltage of the power receiving terminal is detected and the portable terminal is mounted on the charging stand, the secondary battery and the load are disconnected, and power supply from the secondary battery to the load is stopped. And a switching control means for controlling the switching means so that the secondary battery and the load are electrically connected and power is supplied from the secondary battery to the load when the portable terminal is removed from the charging stand. When,
A portable terminal comprising: a first backflow prevention means provided in the second circuit and preventing current from flowing toward the power receiving terminal. A charging circuit provided in the first circuit for controlling a charging current to the secondary battery;
The mobile terminal according to claim 1, wherein the charging circuit limits a charging current from the external power source to the secondary battery.   The portable terminal according to claim 2, wherein the charging circuit performs only one charge when the portable terminal is mounted on the charging stand. It is further equipped with a temperature sensor that detects the ambient temperature,
The portable terminal according to claim 3, wherein charging of the secondary battery is stopped when an outside air temperature unsuitable for the secondary battery is detected.   The mobile terminal according to claim 1, wherein the switching unit is a MOS transistor.   6. The portable terminal according to claim 5, wherein second backflow prevention means is arranged in series with the MOS transistor. The mobile terminal according to any one of claims 1 to 6,
A portable terminal device comprising: a charging stand connected to the external power source and detachable from the portable terminal.

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