JP2003348197A - Mobile communication terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make flash charging for a mobile communication terminal while securing the operation of the terminal even with a battery residual capacity reduced and to accurately display the battery residual capacity even during the flash charging. <P>SOLUTION: A battery residual capacity discrimination function 20a discriminates whether the battery residual capacity is equal to or larger than a preliminarily set first threshold TH1 or not. A capacitor 34 of a flash unit FU is charged in a normal charging mode by a charging mode control function 20b when the battery residual capacity is equal to or larger than the first threshold TH1, and the capacitor 34 of the flash unit FU is charged in a smaller current charging mode having a charging current value smaller than that of the normal charging mode by the charging mode control function 20b when the battery residual capacity is smaller than the first threshold TH1. Charging operation is inhibited when the battery residual capacity is reduced to a second threshold TH2 or lower. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable telephone, a personal digital assistant (PDA),
The present invention relates to a mobile communication terminal such as an S (Personal Handyphone System) terminal, and particularly to a mobile communication terminal having a flash function.

[0002]

2. Description of the Related Art In recent years, portable telephones, portable information terminals, PHs, etc.
2. Description of the Related Art Mobile communication terminals represented by an S terminal and the like are rapidly spreading, and as one of them, a mobile communication terminal having a camera function and a flash function has been developed. These mobile communication terminals record or transmit an image captured by a camera, and can transmit, for example, a user's face, surrounding scenery, and the like to a communication partner as image information. Further, by using the flash function, it is possible to take a picture at night or in a dark room, which is very convenient.

Generally, this type of terminal is provided with a charging / discharging circuit for flash emission, and is configured to charge the charging / discharging circuit by the battery voltage of the terminal and cause a lamp or the like to emit light. Here, when charging the flash circuit using the battery voltage, a large charging current is consumed, so that the voltage drop of the battery becomes large, and depending on the value, the original circuit of the terminal such as the baseband LSI may malfunction. It is very unfavorable because it may cause it. For this reason, when charging, the battery voltage is compared with a threshold value, and when the battery voltage is less than the threshold value, charging is not performed.

[0004]

To ensure the operation of the terminal, the threshold value may be set to a high value. However, in this case, the flash cannot be used even if the battery remaining amount is slightly reduced, and the use time of the flash is shortened. For this reason, it is inconvenient for a user who frequently performs camera flash photography.

In general, the output voltage of a battery is periodically detected in a mobile communication terminal, and the remaining battery level is displayed based on the detected voltage value. However,
As described above, the battery temporarily causes a large voltage drop during the charging period of the flash circuit, so if the remaining battery level is displayed during this period, an erroneous display will be displayed, and the user will have to change the battery replacement time. There is a risk of making a mistake.

The present invention has been made in view of the above circumstances, and has as its object to ensure that the operation of the terminal is ensured even when the remaining battery power is low so that the flash circuit can be charged and used. Another object of the present invention is to provide a mobile communication terminal capable of displaying a more accurate remaining battery level even during flash charging.

[0007]

According to a first aspect of the present invention, there is provided a battery-operated mobile communication terminal including a camera and a flash circuit which emits light in response to a photographing operation of the camera. First charging means for charging the flash circuit with a first charging current value based on the output voltage of the battery; and second charging means for charging the flash circuit based on the output voltage of the battery. Second charging means for charging the flash circuit with a charging current value, remaining battery level detecting means for detecting the remaining battery level, and a first battery level detected by the remaining battery level detecting means. A determination unit for determining whether the value is equal to or larger than a threshold value or less and a control unit for controlling each of the charging units are provided. When the determination means determines that the detected remaining battery level is equal to or greater than the first threshold value, the first charging means is selected to charge the battery. If it is determined that the charge is less than the predetermined value, the second charging means is selected to perform charging.

Therefore, according to the present invention, even when the remaining battery charge falls below the threshold value where charging of the flash has been prohibited in the past, the second charging current value is small.
By using the charging means, the flash circuit can be charged. For this reason, the user can perform flash photography for a long time without replacing the battery. Further, by using the second charging means, the voltage drop of the battery during charging is suppressed.
Therefore, even during charging, the remaining battery level can be displayed more accurately than before.

According to a second aspect of the present invention, the determination means further includes a function of determining whether the remaining battery level is equal to or greater than a second threshold value smaller than the first threshold value. The control means prohibits charging when the remaining battery charge falls below the second threshold value.

Therefore, according to the second invention, when the remaining battery charge is less than the first threshold value and equal to or more than the second threshold value, the second charging means performs charging with a small current. When the remaining amount decreases further below the second threshold value, the charging operation is automatically stopped. For this reason, it is possible to prevent a problem that another circuit in the terminal becomes inoperable due to a decrease in the battery voltage.

In the first and second inventions, when the second charging means is selected, the user may be notified of the fact. With this configuration, it is possible to notify the user that the flash charging is a charging operation in a state where the remaining amount of the battery is low.
The second charging means takes a longer time to charge than the first charging means. However, the user is notified that the second charging unit has been selected as described above, so that the user can recognize that charging takes time.

Further, in the second invention, when the result of the determination by the determining means is less than the second threshold value, the user may be notified of the result of the determination. With this configuration, it is possible to notify the user that the flash function cannot be used, so that when the user wants to perform flash photography, it is possible to call attention to recharging the battery in advance.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a mobile communication terminal according to the present invention will be described below with reference to the drawings. FIG. 1 is an external view showing a configuration in a state where a flash unit FU is connected to a mobile phone MU having a camera function according to an embodiment of the present invention. A key input unit 21, a display unit 22, and a camera 2 are provided on the front panel of the housing of the mobile phone MU.
3 are arranged. An antenna 1 is provided on the upper part of the housing. Further, an earphone jack is provided on a side surface of the housing. A flash unit FU can be detachably attached to the earphone jack. On the front surface of the flash unit FU, a light emitting device 37 and a charging indicator 32 are provided. The charge indicator 32 is made of a neon tube.

FIG. 2 is a block diagram showing a circuit configuration of the mobile phone MU. In the figure, a radio signal transmitted from a base station (not shown) via a radio channel is:
Antenna duplexer (DUP) after received by antenna 1
The signal is input to the receiving circuit (RX) 3 via the second circuit 2. In the receiving circuit 3, the received radio signal is mixed with the local oscillation signal and down-converted into an intermediate frequency signal. The local oscillation signal is generated by a frequency synthesizer (SYN) 4 according to a control signal SCS output from the control circuit 20.
Generated from. The down-converted intermediate frequency signal is converted to a digital signal by an A / D converter 6 including a low-pass filter, and then input to a digital demodulation circuit (DEM) 7.

The digital demodulation circuit 7 first establishes frame synchronization and bit synchronization with the digital intermediate frequency signal, and then performs digital demodulation processing. The baseband demodulated signal obtained by this demodulation processing is input to a time division multiple access (TDMA) circuit 8. The TDMA circuit 8 extracts a time slot addressed to the own terminal from each transmission frame of the baseband demodulated signal. The information of the frame synchronization and the bit synchronization obtained in the digital demodulation circuit 7 is notified to the control circuit 20.

The baseband demodulated signal extracted by the TDMA circuit 8 is subsequently sent to an error correction code decoding circuit (C
H-COD) 9 where it is subjected to error correction decoding processing. The baseband demodulated signal subjected to the error correction decoding includes information data such as mail in the data communication mode, and includes communication data in the communication mode.

The speech data is stored in a speech codec (SP-
The digital audio signal is input to the COD 10 and subjected to voice decoding processing, whereby a digital reception signal is reproduced. The reproduced digital reception signal is converted into an analog reception signal by the D / A converter 11, and then input to a reception amplifier (not shown) via the switching circuit 12. Then, after being amplified by the receiving amplifier, it is supplied to the speaker 13 and output.

Further, information data such as mail and download data is taken into the control circuit 20. Control circuit 20
Stores the fetched information data in a memory (MEM) 24
, And decrypted and displayed on the display unit 22.

On the other hand, a user's transmission signal output from the microphone 14 is amplified to a predetermined level by a transmission amplifier (not shown), and then is switched through an A / D via a switching circuit 15.
It is input to the converter 16. Then, this A / D converter 1
At step 6, it is converted into a digital transmission signal. Subsequently, after the echo is canceled by an echo canceller (not shown), the digital transmission signal is voice-encoded by a voice codec (SP-COD) 10 to become speech data.

The speech data is subsequently input to an error code decoding circuit (CH-COD) 9, where it is subjected to error correction coding. The image data and information data such as mail output from the control circuit 20 are also transmitted to the error code decoding circuit 9.
And error-correction-coded. The transmission data output from the error code decoding circuit 9 is input to the TDMA circuit 8. The TDMA circuit 8 creates a TDMA transmission frame. Then, the transmission data is inserted into the time slot allocated to the own terminal in the created TDMA transmission frame, and the digital modulation circuit (MO
D) Output to 17.

The digital modulation circuit 17 digitally modulates the transmission data. The modulated transmission data is converted into an analog signal by the D / A converter 18 and then input to the transmission circuit (TX) 5. The digital modulation method is, for example, π / 4 shift DQPSK.
(Π / 4 shifted, differentially encoded quadrature
phase shift keying) method is used.

The transmission circuit 5 mixes the modulated transmission data with a local oscillation signal and up-converts it into a radio signal. This radio signal is amplified to a predetermined transmission power level by a transmission power amplifier (not shown), and then supplied to an antenna 1 via an antenna duplexer 2.
Is transmitted to a base station (not shown).

The portable telephone MU has a key input unit 21, a display unit 22, a camera 23, and a memory (ME).
M) 24. The key input unit 21 includes a plurality of function keys such as a call key and an end key, a dial key, a shutter key for operating the camera 23, and a charge key for charging the flash unit FU. ing. The shutter key and the charging key can be shared by the keys required for the communication under software control.

The display section 22 has a liquid crystal display (LCD: Li
quid Crystal Display). Display data output from the control circuit 20 is displayed on the LCD. The display data includes information data such as e-mail and image data, management data such as a telephone directory and transmission / reception history, and pictogram information indicating an operation state of the terminal such as a received electric field strength and a remaining battery level.

The camera 23 is, for example, a CCD (Charge Cou).
pled Device) or CMOS (Complementary Metal Oxi)
The semiconductor device uses a solid-state imaging device such as a de-semiconductor, and is controlled by the control circuit 20. The memory 24 includes, for example, a RAM or a flash memory, and stores a telephone directory, mail and download data received from a terminal or an information site of a communication partner user, and also stores image data captured by the camera 23, outgoing mail, and the like. save.

Reference numeral 26 denotes a power supply circuit, based on the output voltage of a battery 25 composed of a secondary battery, a portable telephone M.
A power supply voltage Vcc required for operation of each circuit of U and a power supply voltage Vss required for charging the flash unit FU are generated.

The battery voltage detecting circuit 19 includes a battery 2
5 is a circuit for detecting the output voltage, and the detected value is converted into digital data by an A / D converter (not shown). The control circuit 20 periodically reads the battery voltage detection value to calculate the remaining battery power, and displays the remaining battery power on the display unit 22. The detected value of the battery voltage is also used for comparison with a threshold value by a battery remaining amount determination function 20a described later.

The mobile phone MU includes an earphone jack 31 and a plug insertion / removal detection circuit 2 as circuits necessary for mounting and using the flash unit FU.
7, a mounting identification circuit 28, and a charging current control circuit 29.

The earphone jack 31 is used for mounting an earphone unit (not shown), and is also used as a connector jack for mounting the flash unit FU. The earphone jack 31 is
The D / A converter 11 and the A / D converter 16 are connected via the switching circuits 12 and 15. Switching circuits 12, 15
Is controlled by the control circuit 20.

The plug insertion / removal detection circuit 27 detects the insertion / removal of the connector plug of the earphone unit or the flash unit FU into / from the earphone jack 31, and notifies the control circuit 20 of the detection signal DET1.

The mounting identification circuit 28 applies a predetermined identification signal to a specific terminal of the earphone jack 31 when the plug insertion is detected by the plug insertion / removal detection circuit 27. Then, it is monitored whether or not the applied identification signal is returned from the flash unit FU as a detection voltage via another specific terminal. The mounting identification signal DET2 indicating whether or not the detection voltage is returned is notified to the control circuit 20.

A charging current control circuit 29 selectively selects a first charging current and a second charging current smaller than the first charging current in accordance with a charging current control signal CAC supplied from the control circuit 20. And supplies it to the flash unit FU.

The control circuit 20 has a microcomputer. As a control function, in addition to a normal control function such as a wireless access control function and a call control function, a new control function according to the present invention includes a battery remaining amount determination function 20a.
And a charging mode control function 20b.

The remaining battery charge determining function 20a has a first threshold value TH1 and a second threshold value TH2 smaller than the first threshold value. Then, the voltage value detected by the battery voltage detection circuit 19 is compared with the first and second threshold values, and a first region where the battery voltage value is equal to or more than the first threshold value TH1 is compared with a first region. It is determined which of three regions, a second region that is less than the threshold value TH1 and equal to or more than the second threshold value TH2, and a third region that is less than the second threshold value TH2.

The charge mode control function 20b is a function for selecting a charge mode when the user presses a charge key for charging the flash. The mobile communication terminal of this embodiment has two types of charging modes. First
Is a normal charging mode in which charging is performed using the first charging current that is sufficiently large so that charging of the flash can be completed quickly. The second charging mode is a small current charging mode using a second charging current set smaller than the first charging current used in the normal charging mode,
Although the flash charging time is longer than in the normal charging mode, the voltage drop of the battery 25 can be kept low. The charge mode control function 20b selects the normal charge mode if the result of comparing the battery voltage value detected by the battery voltage detection circuit 19 with the battery remaining amount determination function 20a is the first area. Then, in the case of the second region, the small current charging mode is selected, and in the case of the third region, control is performed such that flash charging is prohibited.

On the other hand, the flash unit FU and its connector plug 30 are configured as follows. FIG. 3 is a block diagram showing the configuration. Flash unit FU
Is a charging indicator 32 using a neon tube and a power receiving circuit 3
3, a capacitor 34, a signal input circuit 35, a delay control circuit 36, and a light emitting device 37 having a flash lamp.

The power receiving circuit 33 supplies the charging current supplied from the charging current control circuit 29 of the mobile phone MU to the capacitor 34 for charging. When the charging is completed, the result is transmitted to the control circuit 20. Notice. The signal input circuit 35 receives the light emission control signal FRS output from the control circuit 20 of the mobile phone MU. The delay control unit 36 delays the light emission control signal FRS output from the signal input unit 35 by a predetermined delay time and supplies the light emission control signal FRS to the light emitting device 37, thereby discharging the charge of the capacitor 34 and causing the light emitting device 37 to operate. Flash.

The connector plug 30 has five terminals A,
B, C, D, and E are arranged in a line in order from the tip.
Inserted into earphone jack 31. The terminal A of the connector plug 30 is used as a power terminal.
It is connected to the charging current control circuit 29. The terminal B is used as a plug insertion / removal detection terminal and a power receiving terminal for a mounting identification signal. Terminal C is used as a ground terminal and terminal D
Is used as a terminal for receiving the light emission control signal FRS.
The terminal E is connected to the terminal B in the connector plug 30. The mounting identification signal applied to the terminal B is returned from the terminal E of the connector plug 30 to the mounting identification circuit 28 of the mobile phone MU as a detection voltage. You.

Next, the operation of the mobile communication terminal configured as described above will be described. Control circuit 2 in standby state
0 monitors the occurrence of incoming / outgoing calls and the operation of selecting other functions. If an outgoing / incoming call occurs in this state, the mode is shifted to the call mode.

On the other hand, if the user performs a camera mode selection operation, the control circuit 20 sets the camera mode and thereafter starts the control. FIG. 4 is a flowchart showing a control procedure and contents of the control circuit 20 in the camera mode.

When the camera mode is set, the control circuit 2
In step 4a, 0 causes the display unit 22 to operate as a finder, and causes image data captured by the camera 23 to be displayed on the display unit 22. If the user presses the shutter key without selecting the flash mode in step 4b, the process proceeds from step 4c to step 4d, and the captured image data at this point is stored in the memory 24.
When an erasing operation is performed, the corresponding image data stored in the memory 24 is selectively discarded.

When the photographing control operation corresponding to one photograph is completed, the control circuit 20 determines in step 4e whether or not the photographing is completed. Then, in this state, when the user performs an end operation of the camera mode using the key input unit 21, the process proceeds to step 4f, where the camera 23 and the display unit 22
Is stopped, and the camera mode setting is released. On the other hand, if the operation for ending the camera mode is not performed, the process returns to step 4a to repeatedly execute the above-described camera mode control.

On the other hand, suppose that the user presses the charge key to perform flash photography in the state where the camera mode is set. Then, the control circuit 20 detects this operation in step 4b, and thereafter starts the control of the flash mode. FIGS. 5 and 6 are flowcharts showing the control procedure and contents of the control circuit 20 in the flash mode.

When the control circuit 20 detects the operation of the charge key, the control circuit 20 proceeds to step 5a.
Read the battery voltage detection value from. Then, in step 5b, the detected battery voltage value and the first threshold value T
H1 is compared, and if it is equal to or greater than the first threshold value TH1, the normal charging mode is selected in step 5c. On the other hand, if the detected battery voltage value is less than the first threshold value TH1, the process proceeds to step 5d, where the read battery voltage detected value is compared with the second threshold value TH2. If the detected battery voltage value is equal to or greater than the second threshold value TH2, the small current charging mode is selected in step 5e.
If the battery voltage detection value is less than the second threshold value TH2, charging is prohibited in step 5f, and
After that, the photographing operation without using the flash is executed. At this time, the control circuit 20 performs step 5g.
, A message indicating that the flash cannot be used is created, and the created message is displayed on the display unit 22.

Now, the above step 5c or step 5e
When the normal charging mode or the small-current charging mode is selected in, the control circuit 20 first causes the display unit 22 to display a message, an icon or a symbol indicating the charging mode selected in step 6a. Next, in order to perform flash charging, in step 6b, a charging current control signal CAC which is an instruction signal of a charging current corresponding to each charging mode.
To the charging current control circuit 29. As a result, the charging current control circuit 29 outputs the first or second charging current corresponding to the specified mode, and the charging current is supplied to the capacitor of the flash unit FU via the earphone jack 31 and the connector plug 30. 34. Thus, the capacitor 34 of the flash unit FU is charged. FIGS. 7A and 7B show the change in the battery voltage during this charging. FIG. 7A shows the case of the normal charging mode, and FIG. 7B shows the case of the small current charging mode. As shown in the figure, when the small current charging mode is used, the voltage drop of the battery is smaller than that in the normal charging mode. As a result, even when the battery voltage is less than the threshold value TH1, the battery voltage after the voltage drop is reduced. Charging can be performed without the voltage dropping below the threshold value TH2.

When the charging is started, the control circuit 20 monitors in step 6c whether the charging is completed. When the charging is completed, the control circuit 20 continues to step 6d
Step 6 monitors the photographing operation and detects the photographing operation in Step 6.
At step e, the light emission control signal FRS is given to the signal input circuit 35 of the flash unit FU. As a result, the charge of the capacitor 34 is emitted by the light emitter 37 with a delay of a preset delay time.

Therefore, according to this embodiment, even if the battery voltage is lower than the first threshold value TH1 which conventionally prohibited charging of the flash unit FU, the battery voltage is equal to or higher than the second threshold value TH2. Then, flash charging becomes possible by using the small current charging mode.
In the small current charging mode, the charging current is small and the voltage drop of the battery can be suppressed low. Therefore, even if the battery voltage is detected during the charging period to display the remaining battery level, the voltage drop is usually large. It is possible to display more accurately than in the charging mode.

Further, when the small-current charging mode is selected, the user is notified that the small-current charging mode is selected, so that the flash charging is a charging operation in a state where the remaining amount of the battery is low. You can let them know. The small current charging mode takes a longer time to charge than the normal charging mode. However, by being notified that the small current charging mode is selected as described above,
The user can recognize that charging takes time.

Further, in the above embodiment, when the result of the determination by the remaining battery charge determining function 20a is less than the second threshold value TH2, the user is notified of the fact. Therefore, the user can know that the flash function cannot be used, and can take measures such as charging or replacing the battery in advance when flash photography is desired.

The present invention is not limited to the above embodiment. For example, in the above-described embodiment, a case has been described in which two modes of the normal charging mode and the small current charging mode are used as the charging mode. However, three or more charging modes having different charging current values are prepared and the battery voltage detection value is set. May be configured to selectively use these charging modes in accordance with. With this configuration, it is possible to further extend the period during which flash charging is possible.

In each charging mode, a configuration may be adopted in which a battery voltage drop is detected during the charging period, the remaining battery voltage is corrected, and the remaining battery capacity is calculated and displayed. With this configuration, the effect of the battery voltage drop can be reduced, and more accurate remaining battery level display can be performed.

Further, the flash unit may be a built-in type other than the external type.

In addition, the type and configuration of the mobile communication terminal, the configuration of the flash unit, the type of the light emitting element used as the light emitting unit, the procedure and contents of the camera photographing and flash photographing control, and the procedure and contents of the charge control of the flash unit ,
The control procedure and contents of the remaining battery level display can be variously modified without departing from the gist of the present invention.

[0054]

As described above in detail, according to the first aspect, the remaining battery level is determined in a battery-driven mobile communication terminal including a camera and a flash circuit that emits light in response to a shooting operation of the camera. A first threshold value for performing flash charging by the first charging means when the detected remaining battery level is equal to or greater than the first threshold value. If the threshold value is less than 1, the flash charging is performed by the second charging means having a smaller charging current value than the first charging means.

Further, in the second invention, in addition to the configuration of the first invention, a second threshold value smaller than the first threshold value is further provided, and the detected remaining battery level is set to the second threshold value. If it is less than the threshold, the flash charging operation is prohibited.

Therefore, according to these inventions, even when the remaining battery charge falls below the threshold value where charging of the flash has been prohibited in the past, the second charging means having a small charging current value can be used. Thus, the flash circuit can be charged. For this reason, the user can perform flash photography for a long time without replacing the battery. Further, since the voltage drop of the battery during charging is suppressed by using the second charging means, a mobile communication terminal capable of displaying the remaining battery level more accurately even during charging than before is provided. Can be provided.

[Brief description of the drawings]

FIG. 1 is an external view showing a configuration in a state where a flash unit FU is connected to a mobile phone MU having a camera function according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a circuit configuration of the mobile phone MU shown in FIG.

FIG. 3 is a block diagram showing a circuit configuration of the flash unit FU shown in FIG. 1;

FIG. 4 is a flowchart showing a control procedure and contents in a camera mode of the mobile communication terminal shown in FIG. 1;

FIG. 5 is a flowchart showing a first half of a control procedure in a flash mode of the mobile communication terminal shown in FIG. 1;

FIG. 6 is a flowchart showing the latter half of the flash mode control procedure of the mobile communication terminal shown in FIG. 1;

FIG. 7 is a diagram showing changes in battery voltage in a normal charging mode and a small current charging mode of the mobile communication terminal shown in FIG.

[Explanation of symbols]

1. Antenna 2: Antenna duplexer (DUP) 3. Receiving circuit (RX) 4: Frequency synthesizer (SYN) 5. Transmission circuit (TX) 6,16 ... A / D converter 7 Digital demodulation circuit (DEM) 8. Time division multiple access circuit (TDMA) 9 ... Error correction code decoding circuit (CH-COD) 10. Voice code decoding circuit (SP-COD) 11, 18 ... D / A converter 12, 15 ... switching circuit 13. Speaker 14. Microphone 17 Digital modulation circuit (MOD) 19 ... Battery voltage detection circuit 20 ... Control circuit 20a: Battery remaining capacity judgment function 20b ... charge mode control function 21 ... Key input section 22 Display unit 23… Camera 24 ... Memory (MEM) 25 ... Battery 26 ... Power supply circuit (POW) 27 ... Plug insertion / removal detection circuit 28 ... Mounting identification circuit 29 ... Charge current control circuit 30 ... Connector plug 31 ... Earphone jack 32 ... Charge indicator 33 ... Power receiving circuit 34… Capacitor 35 ... Signal input circuit 36 ... Delay control circuit 37 ... Light emitter

Claims (4)

[Claims] 1. A battery-operated mobile communication terminal comprising: a camera; and a flash circuit that emits light in response to a photographing operation of the camera, wherein the first charging current value is determined based on an output voltage of the battery. First charging means for charging a flash circuit; second charging means for charging the flash circuit with a second charging current value smaller than the first charging current value based on the output voltage of the battery; Battery remaining amount detecting means for detecting the remaining amount of the battery; determining means for determining whether the battery remaining amount detected by the battery remaining amount detecting means is equal to or greater than a first threshold value; When the determination unit determines that the detected remaining battery level is equal to or greater than a first threshold value, the first charging unit is selected to perform charging, while the detected battery level is determined. Mobile communication terminal, characterized by comprising a control means for causing the charge to select the second charging means when Teri remaining is determined to be less than the first threshold. 2. The method according to claim 1, wherein the determining unit determines whether the remaining battery level detected by the remaining battery level detecting unit is equal to or greater than a second threshold value smaller than the first threshold value. The control unit further includes a function of prohibiting charging when the determination unit determines that the detected remaining battery level is less than a second threshold value. The mobile communication terminal according to claim 1. 3. The mobile communication terminal according to claim 1, further comprising a first notifying unit that notifies a user when the second charging unit is selected. 4. The method according to claim 1, wherein the determining unit determines that the remaining battery level is less than the second threshold value, and further notifies the user that charging is prohibited. The mobile communication terminal according to claim 2, comprising: