JP2001268220A - Mobile communication terminal and its display control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mobile communication terminal that can maintain easy to see display image, even when the lightness is changed rapidly and to suppress the power consumption and to provide a display control method. SOLUTION: The mobile communication terminal is provided with a transmission reception, that transmits/receives a signal, a display section having a display screen on which data sent/received via the transmission reception section are displayed, a control section that controls the transmission reception section and the display section, an entry key that enters data or an operation command to the control section, and a photosensor that detects the surrounding lightness. When the display section displays an image and the surrounding lightness exceeds a predetermined lightness, the control section limits power supplied to the display section, when the surrounding lightness is the predetermined lightness or lower, the control section increases the power supplied to the display section. When the surrounding lightness reaches the predetermined lightness or lower within a predetermined time, the control section once increases the lightness of the display screen and then restores the lightness to the prescribed lightness as its control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable communication terminal device comprising a display unit having a display screen for displaying data to be transmitted and received, button keys for inputting signals, a timer for controlling them, and a control unit. And a brightness control method.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Laid-Open No. 02-104055
As disclosed in Japanese Unexamined Patent Application Publication No. H11-264, the control of the backlight that illuminates the display unit is turned on and off for a certain time when a signal is input. In addition to this, when a button is pressed, for example, in a mobile phone device, a backlight for illuminating the display unit is turned on so that the liquid crystal can be seen even in a dark place, and an operation such as pressing a button is performed for a certain time. If not, the backlight was turned off to reduce power consumption.

Further, as disclosed in Japanese Patent Application Laid-Open No. Hei 10-200615, there is an apparatus in which display control of a backlight is performed according to a detected program and an operation state of a telephone. In this prior art, the backlight is turned off during a call while an application program for a voice call is operating, and the backlight is turned on in other states such as dialing. Also, the backlight is controlled to be turned on whenever the short message application or the telephone setting application is operating.

Japanese Patent Application Laid-Open No. 9-27844 discloses that
2. Description of the Related Art A mobile phone that controls a backlight by detecting ambient brightness with a light receiving element has been disclosed. In this method, the surrounding brightness is detected by a light receiving element, and control is performed so that the backlight is turned on when the brightness is lower than a set threshold value. The backlight is turned off at a predetermined time after being turned on by a timer.

[0005]

Since a large-capacity battery cannot be mounted on a portable communication terminal device in order to reduce the size and weight, power consumption is a problem. For this reason, in the related art, on / off control of a backlight of a liquid crystal display is performed, but no consideration is given to a response to a sudden change in ambient brightness. For example, in a case where mail is transmitted and received in a passenger seat or a rear seat of a passenger car, or in a car such as a train or a bus, the brightness rapidly changes when the car, train or bus enters a tunnel.
In this case, although the backlight is turned on in the conventional technology for detecting the brightness, the phenomenon that the display screen becomes hard to see because the user's eyes cannot follow the rapid change in brightness may occur. If the brightness of the backlight is increased to prevent this, the power consumption may increase and the life of the battery may be shortened.

An object of the present invention is to provide a portable communication terminal device capable of maintaining the visibility of a display screen even when the brightness changes rapidly and suppressing power consumption, and a display control method therefor.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a portable communication terminal with a transmitting / receiving unit for transmitting / receiving signals and a display screen for displaying data transmitted / received via the transmitting / receiving unit. A control unit for controlling the transmitting and receiving unit and the display unit, an input key for inputting data or an operation command to the control unit, and an optical sensor for detecting ambient brightness. When display is performed on the screen, when the ambient brightness exceeds a predetermined brightness, the power supplied to the display unit is limited, and when the ambient brightness is equal to or less than the predetermined brightness, the power is supplied to the display unit. While increasing the power to be supplied, if the ambient brightness falls below a predetermined brightness within a predetermined time, the brightness of the display screen is increased once and then to the predetermined brightness. To return It is characterized in that Gosuru.

In a preferred embodiment, the display unit includes a liquid crystal display unit and a backlight for illuminating the liquid crystal display unit, and when the display is performed on the liquid crystal display unit, the surrounding brightness is set to a predetermined brightness. When the ambient brightness exceeds the predetermined brightness, the power supplied to the backlight is increased when the ambient brightness is equal to or less than the predetermined brightness. When the brightness becomes equal to or less than the predetermined brightness, the brightness of the backlight is increased once and then controlled to gradually return to the predetermined brightness.

Further, the present invention provides a display unit having a display screen for displaying data transmitted / received via a transmission / reception unit for transmitting / receiving a signal, a control unit for controlling the transmission / reception unit and the display unit, and an ambient brightness. A display control method for a mobile communication terminal device including an optical sensor that detects the ambient brightness based on an output of the optical sensor, and the ambient brightness is reduced when a display is performed on a display screen. When the brightness exceeds a predetermined brightness, the control unit limits the power supplied to the display unit, and when the surrounding brightness becomes equal to or less than the predetermined brightness when the display is performed on the display screen, the control unit performs It is determined whether the surrounding brightness has become equal to or less than a predetermined brightness within a predetermined time, and when the surrounding brightness has become equal to or less than a predetermined brightness within a predetermined time, the above display is performed. Reduce screen brightness The power supplied to the display unit is controlled so as to return to the predetermined brightness after the increase, and the display screen is displayed when the ambient brightness becomes equal to or less than the predetermined brightness for more than a predetermined time. Controlling the power supplied to the display unit such that the brightness of the image becomes a predetermined brightness.

[0010]

FIG. 1 is a block diagram showing an embodiment of the present invention.
This will be described with reference to FIG. FIG. 1 is a block diagram showing a configuration of a mobile communication terminal device according to the first, second, and third embodiments of the present invention.
The hardware is common to each embodiment, and will be described together. The mobile communication terminal device according to the present embodiment includes a transmitting / receiving unit 5 for transmitting / receiving signals, a display unit 3 having a display screen 32 for displaying data transmitted / received via the transmitting / receiving unit 5, The control unit 2 includes a control unit 2 for controlling the display unit 3, an input key 1 for inputting data or an operation command to the control unit 2, and an optical sensor 4 for detecting ambient brightness. The input key 1 is configured as a key button section, and performs operations of the mobile communication terminal device and input of characters by pressing one or more buttons (input keys) among a plurality of key buttons. The transmission / reception unit 5 receives a signal from the communication line A, outputs communication data and control data to the control unit 2, and transmits a signal from the control unit 2 and data to be sent to the communication line A. For example, when the mobile communication terminal device is a mobile phone, the transmission / reception unit 5 includes an antenna, a high-frequency circuit, a modulation / demodulation circuit, and a signal processing circuit.

The control unit 2 includes a microcomputer (hereinafter referred to as C).
PU) and controls the entire mobile communication terminal device, and also controls the display unit 3 based on a signal from the input key 1, an input signal from the transmission / reception unit 5, and an input signal from the optical sensor 4. As the optical sensor 4, a photodiode, a phototransistor, or the like is used to reduce the occupied area on the substrate. The control unit 2 further controls the timer unit 21 to control the power supply time to the display screen 32 of the display unit 3 so that the display screen 32 has a predetermined brightness for the time set by the timer unit 21. I do. In the present embodiment, the display screen 32 of the display unit 3 is a liquid crystal display, and the backlight 3
Illuminated by 1. The control unit 2 receives a signal input by pressing the input key 1, a communication line input from the transmission / reception unit 5, a signal for identifying voice communication or non-voice communication, an optical sensor 4
When the input signal is input to the backlight 31 as a control start condition, the backlight 31 is turned on and a display based on the signal input is displayed on the liquid crystal display unit 32 when the signal is input. The brightness of the backlight 31 is controlled by the control unit 2. The lighting time of the backlight 31 is controlled by the timer unit 21. In the present embodiment, the timer unit 21
Is the control unit 2 itself, and the CPU performs a timing operation by software. Therefore, the control unit 2 controls the brightness and the lighting time of the backlight 31.

The controller 2 detects the brightness of the surroundings based on the output of the optical sensor 4 when displaying on the display screen 32, and when the brightness of the surroundings exceeds a predetermined brightness. The power supplied to the display unit is limited, and the power supplied to the display unit is increased when the ambient brightness is equal to or less than a predetermined brightness. Specifically, the controller 2 limits the power supplied to the backlight 31 when the surrounding brightness exceeds a predetermined brightness when the display is performed on the display screen 32 of the liquid crystal display. To reduce the brightness of the backlight 31 or to turn off the backlight 31. On the other hand, when the surrounding brightness is equal to or less than the predetermined brightness, the control unit 2 increases the power supplied to the backlight 31 to turn on the backlight 31 or increase the brightness of the backlight 31.

An example of the control will be described with reference to FIGS. FIG. 2 shows the first embodiment of the present invention in which the control unit 2 determines the surrounding brightness and then controls the lighting of the backlight 31. FIG. 3 shows the second embodiment of the present invention. Light 3
1 is turned on once, and the control unit 2 determines the brightness of the surroundings to control the lighting of the backlight 31. In the first embodiment, as shown in FIG. 2, the controller 2 determines the surrounding brightness by pressing a key button or the like (step S201) (step S202). If it is dark, the backlight 31 is turned on (step S203), and it is determined whether or not a non-voice call is made (step S204). “Pressing a key button or the like” includes not only input from the key button but also detection of signal reception by the transmission / reception unit. The “non-voice call” is a communication by transmitting and receiving a character, a symbol, a graphic, or the like without using a voice represented by an email, for example. In the case of the mail communication mode, it is determined in step S204 whether the message is being read. When the determination in step S204 is No, that is, in the case of voice communication such as telephone, the display screen is hardly seen, so that the backlight 31 is turned on for a preset time T0 so that the backlight is turned on for a short time (step S204). S210) In the case of non-voice communication, the communication is performed while looking at the display screen, so that the backlight is turned on for a time T1, which is set long in advance so that the backlight is turned on for a long time (step S220). After the time T0 has elapsed in step S210 and after the time T1 has elapsed in step S220, the process proceeds to steps S215 and S225, respectively, where power supply to the backlight 31 is stopped and the backlight 31 is turned off. Also, even when the surroundings are determined to be bright in step S202, power is not supplied to the backlight 31, and the backlight 31 is kept off (step S205). In this embodiment, the power supply to the backlight 31 is limited by stopping the power supply.

In the second embodiment, as shown in FIG. 3, the controller 2 first turns on the backlight 31 by pressing a key button or the like (step S301) (step S302). “Pressing a key button or the like” includes not only input from the key button but also detection of signal reception by the transmission / reception unit. Next, the control unit 2 determines the surrounding brightness (step S303). When the surrounding brightness is low, the control unit 2 determines whether or not a non-voice call is made with the backlight 31 kept on (step S304). . The “non-voice call” is a communication by transmitting and receiving a character, a symbol, a graphic, or the like without using a voice represented by an email, for example. In the case of the mail communication mode, it is determined in step S304 whether a message is being read. Step S
When the determination in 304 is No, that is, in the case of voice communication such as telephone, the display screen is hardly seen, so that the backlight 31 is turned on for a preset time T0 so that the backlight is turned on for a short time (step S310). ),
In the case of non-voice communication, communication is performed while looking at the display screen, so that the backlight is turned on for a preset long time T1 so that the backlight is turned on for a long time (step S32).
0). After the time T0 elapses in step S310 and after the time T1 elapses in step S320, the process proceeds to steps S315 and S325, respectively, where power supply to the backlight 31 is stopped and the backlight 31 is turned off. Also,
If it is determined in step S303 that the surroundings are bright, the power supply to the backlight 31 is stopped, and the backlight 31 is turned off (step S205). In this embodiment, the power supply to the backlight 31 is limited by stopping the power supply.

In the first embodiment and the second embodiment, the backlight 21 is controlled by the timer 21 for the time T0 and the time T1 after determining the surrounding brightness and the non-voice communication. In the backlight control at the time of reading a mail, the backlight is turned on for a predetermined time T1 so that the backlight is turned on long at the time of the reading operation of the mail. If there is no timer, the backlight is turned on for a predetermined time T0 so that the backlight turns on shortly.
1 is controlled.

A third embodiment of the present invention will be described with reference to FIG. In this embodiment, the backlight 31 is controlled by always detecting the surrounding brightness. As shown in FIG. 10, the controller 2 determines the surrounding brightness by pressing a key button or the like (step S401) (step S40).
2) If the surrounding brightness is low, the control unit 2 determines whether the backlight 31 needs to be turned on (step S40).
3). The determination in step 403 is made based on whether or not a non-voice call or, in the case of the mail communication mode, whether or not a message is being read. If the determination in step S403 is No
In the case of, that is, during a non-voice call or reading a message, the communication is performed while looking at the display screen, so that the backlight 31 is turned on (step S404). Step S
If at least one of step 402 and step S403 is Yes, the process proceeds to step S405, in which the power supply to the backlight 31 is stopped and the backlight 31 is turned off. After the backlight 31 is turned on or off in step S404 or S405, it is determined in step 406 whether the communication state or the operation state is completed. If the determination is Yes, the process proceeds to step S415 to turn off the backlight 31 (step S415). ). If step S405 is No, the process returns to step S402, and steps S402 to S40
Repeat 6.

In the first and second embodiments of the present invention, the control unit 2 further measures the time required for the surrounding brightness fluctuation by the timer unit 21 so that the surrounding brightness is determined in advance. When the brightness becomes equal to or less than a predetermined brightness within a predetermined time, control is performed so that the brightness of the display screen 32 is increased once and then returned to the predetermined brightness. In particular,
As shown in FIG. 5 and FIG.
Is controlled to increase the brightness once and then gradually return to a predetermined brightness. The term “gradually return” means that the brightness is reduced continuously or stepwise from the brightness increased within the time set by the timer unit 21 to a preset brightness. Alternatively, the brightness that has been increased by the time set by the timer unit 21 may be maintained, and then the brightness may be reduced to a preset brightness.

Now, it is assumed that, as shown in FIG. 5A, the surrounding brightness level L has decreased to a level below the threshold value Lth after a time T3. The level after this decrease is a level of brightness in which it is difficult to read characters and the like with the naked eye without the help of lighting, for example, in an unlit tunnel or outdoors at night. When the time T3 is short, for example, a few seconds or less, the brightness level S visually perceived by the user drops once as shown in FIG. Ascend to a certain level. The time T4 at which the eyes become accustomed varies from individual to individual, but is considered to be in the range of several seconds to several minutes.

In the first embodiment of the present invention, step S
If the brightness level falls below the threshold value Lth within the short time T3 in 202, the backlight 31 becomes brighter than the normal brightness for the time T5 as shown in FIG. 5C. The control unit 2 controls the power supplied to 31. The time T5 is desirably slightly longer than the time T4, but is set to about 10 seconds from the viewpoint of power consumption reduction. If a non-voice call is determined in step S204, the backlight 31 is turned on for a time T1 thereafter. As a power supply pattern to the backlight 31, in addition to FIG. 5C, as shown in FIG.
5 (e), the power gradually decreases within a time T5 as shown in FIG. 5 (e), and FIG. 5 (f).
As shown in FIG. 5, there is a case where the power drops to the power of the normal brightness after the time T5.

On the other hand, in step S202, if the brightness level falls below the threshold value Lth within the time T6 (T6> T3) (for example, T6 = several tens of seconds), the brightness visually sensed by the user As shown in FIG. 6 (b), the level S is almost the same as the change in the level of the brightness, because the familiarity of the eye can be almost followed. In this case, as shown in FIG. 6C, when the brightness level L falls below the threshold value Lth, the backlight 31 is turned on at normal brightness, and step S
If a non-voice call is determined in 204, the backlight 31 is turned on for a time T1 thereafter.

In the second embodiment of the present invention, first, the backlight 31 is turned on with normal brightness, and step S3 is performed.
If the brightness level falls to below the threshold Lth within the short time T3 at 03, the backlight 31 becomes brighter than the normal brightness for a time T5 from that point in time, as shown in FIG. 7C. The control unit 2 controls the power to be supplied to the backlight 31. The time T5 is set to about 10 seconds as in the first embodiment. Step S30
If a non-voice call is determined in step 4, then time T1
During this time, the backlight 31 is turned on. Backlight 31
As shown in FIG. 5D, FIG. 5E, and FIG. 5F, the power supply pattern to the power supply is the same as in the first embodiment.

On the other hand, if the brightness level falls below the threshold value Lth within the time T6 (T6> T3) in step S303 (for example, T6 = several tens of seconds), the brightness visually sensed by the user As shown in FIG. 8 (b), the level S is almost the same as the change in the brightness level because the familiarity of the eye can be almost followed. In this case, as shown in FIG. 8C, the backlight 31 is turned on at normal brightness in step S302, and if a non-voice call is determined in step S204, the same brightness is maintained for the time T1 thereafter. It is turned on.

In order to determine the time when the brightness level changes, another threshold value Ls is set on the side brighter than the threshold value Lth as shown in FIG. 9, for example, and the brightness is changed from Ls to Lth.
The determination may be made from the time between the two.

In the third embodiment of the present invention, FIG.
One of the power supply pattern shown in FIG. 7C and the power supply pattern shown in FIG. In the case of the third embodiment, the backlight 31 is turned off not at a predetermined time T0 or T1, but at steps S402 and S402.
Although it is different from the first embodiment and the second embodiment at the time when it is determined that the backlight is turned off in 403 and S406, the power supply pattern is the same.

Thus, for example, when sending and receiving e-mails in a passenger seat or a rear seat of a passenger car, or in a car such as a train or a bus, the passenger car or the train or a bus enters the tunnel and the surrounding brightness is reduced. Suddenly darkens, the backlight 31 is initially lit brightly, and returns to the preset brightness when the user's eyes are accustomed to darkness. Since the change in brightness on the display screen takes time even before and after, it is possible to prevent the display from being temporarily difficult to see, and information can be continuously obtained from the display screen. Also, backlight 3
Since 1 is brightly lit only during the first time when the brightness suddenly becomes dark, a large increase in power consumption can be prevented.

The control unit 2 has a transmitting / receiving unit 5
When there is an input from the user, there is a function of negotiating communication settings such as setting of voice communication or data communication, and setting of communication speed by setting communication rate. That is, as shown in FIG. 4, when calling, (1) a signal is sent from the terminal side to the line side to report the desired communication setting, and (2) an approval signal is sent from the line side if the desired setting is possible. I will send you. If it is not possible, a non-approval signal and possible communication settings are sent. (3) The communication setting is determined by negotiating several times as in (4), and (5) communication based on the determined setting is started. Conversely, even at the time of reception, negotiations are similarly performed with the line side to start communication. As described above, since the control unit 2 negotiates with the line side to set the communication with respect to the signal input from the transmission / reception unit 5, the communication state can be known. Therefore, it is possible to determine whether the communication state is voice communication or non-voice communication as described in FIGS. Also, since the control unit 2 controls the liquid crystal display at each operation, it knows what operation is being performed when the button is pressed. It is possible to determine when a liquid crystal backlight is required, and to determine an operation state such as a message reading operation.

In the communication state of data reception only, when it is not necessary to particularly look at the display screen but wants to check only the connection, the backlight of the liquid crystal may be controlled to blink slowly. . In this case, the connection can be checked at any time and the power consumption can be reduced.

[0028]

According to the present invention, it is possible to obtain a portable communication terminal device capable of maintaining the visibility of the display screen even when the brightness changes suddenly and suppressing power consumption, and a display control method thereof.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a portable communication terminal device according to a first embodiment and a second embodiment of the present invention.

FIG. 2 is a flowchart illustrating a flow of a backlight control operation of the mobile communication terminal device according to the first embodiment of the present invention.

FIG. 3 is a flowchart showing a backlight control operation flow of the mobile communication terminal device according to the second embodiment of the present invention.

FIG. 4 is a diagram illustrating exchange of communication settings between a communication device of a portable communication terminal device and a line side according to the first embodiment and the second embodiment of the present invention.

FIG. 5 is a diagram illustrating a power supply pattern for backlight control of the mobile communication terminal device according to the first embodiment of the present invention, and FIG. 5 (a) illustrates a sudden change in ambient brightness. FIG. 2B is a diagram showing a change in visual brightness.
FIG. 3C shows the first pattern of the power supply pattern to the backlight.
FIG. 3D is a diagram showing a second example of a power supply pattern to the backlight, and FIG. 4E is a diagram showing a third example of a power supply pattern to the backlight; FIG. 11F is a diagram showing a fourth example of a power supply pattern to the backlight.

FIG. 6 is a diagram illustrating a power supply pattern for backlight control of the mobile communication terminal device according to the first embodiment of the present invention, and FIG. 6A illustrates a gradual change in ambient brightness. FIG. 2B is a diagram showing a visual change in brightness, and FIG. 2C is a diagram showing an example of a power supply pattern to a backlight.

FIG. 7 is a diagram illustrating a power supply pattern for backlight control of the mobile communication terminal device according to the second embodiment of the present invention, and FIG. 7A illustrates a sudden change in ambient brightness. FIG. 2B is a diagram showing a change in visual brightness.
FIG. 3C is a diagram illustrating an example of a power supply pattern to the backlight.

FIG. 8 is a diagram illustrating a power supply pattern for backlight control of the mobile communication terminal device according to the second embodiment of the present invention, and FIG. 8A illustrates a gradual change in ambient brightness. FIG. 2B is a diagram showing a visual change in brightness, and FIG. 2C is a diagram showing an example of a power supply pattern to a backlight.

FIG. 9 is a diagram illustrating an example of a method of detecting a change time of surrounding brightness by backlight control of the portable communication terminal device according to the first embodiment and the second embodiment of the present invention.

FIG. 10 is a flowchart illustrating a flow of backlight control operation of the mobile communication terminal device according to the third embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Input key, 2 ... Control part, 3 ... Display part, 4 ... Optical sensor, 5 ... Transceiving part, 21 ... Timer part, 31 ... Backlight, 32 ... Display screen

Continued on the front page (72) Inventor Akio Shinagawa 1410 Inada, Hitachinaka-shi, Ibaraki Prefecture F-term in Digital Media Products Division, Hitachi, Ltd. 5K027 AA11 BB17 GG08 5K067 BB04 CC21 DD51 EE02 FF02 FF23 FF32

Claims (3)

[Claims] A transmitting / receiving unit for transmitting / receiving a signal; a display unit having a display screen for displaying data transmitted / received via the transmitting / receiving unit; a control unit for controlling the transmitting / receiving unit and the display unit; An input key for inputting data or an operation command to the control unit, and an optical sensor for detecting ambient brightness, wherein when the display is performed on the display screen, the ambient brightness is set to a predetermined brightness. When the ambient brightness exceeds the predetermined brightness, the power supplied to the display unit is limited, and when the ambient brightness is equal to or less than a predetermined brightness, the power supplied to the display unit is increased, and the ambient brightness is predetermined. A mobile communication terminal device that, when the brightness becomes equal to or less than a predetermined brightness within a predetermined time, controls to increase the brightness of the display screen once and then return to a predetermined brightness. 2. The display section includes a liquid crystal display section and a backlight for illuminating the liquid crystal display section. When the display is performed on the liquid crystal display section, the surrounding brightness changes to a predetermined brightness. When it exceeds, the power supplied to the backlight is limited, and when the surrounding brightness is equal to or less than a predetermined brightness, the power supplied to the backlight is increased, and the surrounding brightness is set for a predetermined time. 2. The mobile phone according to claim 1, wherein when the brightness becomes lower than a predetermined brightness, the brightness of the backlight is increased once and then gradually returned to a predetermined brightness. Communication terminal device. 3. A display unit having a display screen for displaying data transmitted / received via a transmission / reception unit for transmitting / receiving a signal, a control unit for controlling the transmission / reception unit and the display unit,
A display control method for a mobile communication terminal device including an optical sensor that detects ambient brightness, wherein the control unit determines ambient brightness based on an output of the optical sensor, and a display is performed on the display screen. When the surrounding brightness exceeds a predetermined brightness when the display is on, the control unit limits the power supplied to the display unit, and when the display is performed on the display screen, the surrounding brightness is predetermined. When the brightness becomes equal to or less than the predetermined brightness, the control unit determines whether the surrounding brightness has become equal to or less than a predetermined brightness within a predetermined time, and determines whether the surrounding brightness has decreased within a predetermined time. When the brightness becomes equal to or less than a predetermined brightness, the brightness of the display screen is increased once, and then the power supplied to the display unit is controlled so as to return to the predetermined brightness. Beyond the specified time Display control method of the mobile communication terminal device and controls the power supplied to the display unit so that the brightness of the brightness of the display screen is predetermined when it becomes less than the brightness was fit.