JP2003348224A - Method for concealing password, portable telephone set and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a portable telephone set capable of preventing a password from being inputted in error and securing the secrecy of the password. <P>SOLUTION: The portable telephone set enabled to be connected to a network comprises a display part 107 provided with a back light and a control part 103 for displaying a picture including a password input field for inputting a password on the display part 107, and when the password input field is selected, sending a control signal for turning off the back light to the display part 107. <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 password concealing method for inputting a password to a portable telephone connectable to the Internet, a portable telephone equipped with the method, and a program for password concealment processing.

[0002]

2. Description of the Related Art In recent years, portable telephones and PDAs (personal digital assistants) have been developed.
2. Description of the Related Art Portable terminal devices that can be connected to the Internet, such as nal Digital Assistants (portable information terminals), have become widespread. The purpose of the Internet connection by the portable terminal device was to use e-mail and browse contents for the portable terminal at first, but recently, there are bank caching and information provision for specific members.

[0003] Contents that provide information for bank caching and specific members include information that is highly confidential because of the need to handle personal data.
And the password is used to authenticate the content user. The information provider transmits a user ID and a password which are registered in advance by, for example, transmitting a user ID and a password consisting of a plurality of characters to a connection requester or an information requester of the content. Authenticate by comparing with.

As a method of displaying a user ID and a password on a mobile phone at the time of inputting the password, generally, the input number and characters are displayed as they are on the display screen of the mobile phone, but the password is kept secret. Due to the nature, input numbers and characters are often displayed as "*" instead of being displayed as they are.
Therefore, as the password, for example, “abcd”
, The characters displayed on the display screen of the mobile phone are "****".

When characters are input to a mobile phone, the number of buttons to be arranged is limited. Therefore, a plurality of characters are assigned to each button so that a plurality of characters can be input with one button. For example, the first button is a, b, c
Is assigned, and d, e, and f are assigned to the second button, the following operation is required to input "abcd".

[0006] First, the first button is pressed once to determine the character "a", and then the second button is pressed twice to determine the character "b". The character "c" is determined by pressing the button three times, and finally the character "d" is determined by pressing the second button once. Such operations are:
There is a risk that the user may make an erroneous input, and when inputting a password, the screen display becomes “****” as described above, so it is difficult to confirm whether the password has been input correctly. There are cases.

As a method for solving such a problem, for example, Japanese Patent Application Laid-Open No. 2001-168443 discloses a means for confirming input characters of a password while keeping the password secret. In this gazette, when entering a password, only the last one of the entered characters is displayed on the screen of the mobile phone from the time one character is input until the next character is input, and the input characters are displayed one by one. A method for preventing erroneous input by checking is disclosed.

[0008]

However, in the method disclosed in the above-mentioned publication, a character which is a part of the password is displayed on the screen from the time when one character is input until the time when the next character is input. This means that others may be able to see the entire password, one character at a time. Therefore, even if erroneous input of a password can be prevented, there is a problem in securing confidentiality and security of the password.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and a portable telephone capable of preventing erroneous input of a password and securing confidentiality of the password. It is an object to provide a password concealment method and a program for password concealment processing.

[0010]

A password concealment method according to the present invention for achieving the above object has a display unit provided with a backlight, and is used when a password is input to a portable telephone connectable to a network. A password concealing method, wherein a screen including a password input field for inputting a password is displayed on the display unit, and the backlight is turned off when the password input field is selected.

Further, the password concealing method of the present invention has a display unit provided with a backlight, and is a password concealment method when a password is input to a portable telephone connectable to a network. A screen including a password input field for inputting a password is displayed, and when the password input field is selected, the brightness of the backlight is reduced.

Further, the password concealing method of the present invention comprises:
A password concealment method when a password is input to a mobile phone connectable to a network, comprising a display unit having a liquid crystal screen, wherein a screen including a password input field for inputting a password to the display unit is provided. When the password input field is displayed, the display density of the liquid crystal screen is reduced.

A portable telephone according to the present invention for achieving the above object is a portable telephone connectable to a network, comprising a display unit having a backlight, and a password input field for inputting a password to the display unit. And a control unit that sends a control signal for turning off the backlight to the display unit when the password input field is selected.

A portable telephone according to the present invention is a portable telephone connectable to a network, comprising a display unit having a backlight, and a backlight lighting circuit for adjusting the brightness of the backlight in a stepwise manner. And displaying a screen including a password input field for inputting a password on the display unit, and when the password input field is selected, controls the backlight lighting circuit to reduce the brightness of the backlight. And a control unit for transmitting a signal.

In this case, the backlight has a plurality of light emitting diodes, and the backlight lighting circuit includes an ON / OF of each light emitting diode connected to each of the light emitting diodes.
The control unit may include an FET serving as an F switch, and may output a control signal for turning off some of the FETs.

Further, the mobile phone of the present invention is a mobile phone connectable to a network, and stores a display unit having a liquid crystal screen and a density setting value for making the display density of the liquid crystal screen lower than usual. Display a screen including a password input field for inputting a password on the display unit, and when the password input field is selected, the density setting value is read from the memory unit, and the read density setting is read. A control unit for sending a control signal for setting the value to the display unit.

According to another embodiment of the present invention, there is provided a program having a display unit provided with a backlight, and concealing a password displayed on the display unit in a processor provided in a mobile phone connectable to a network. A program including a password input field for inputting a password on the display unit, and controlling the backlight to be turned off when the password input field is selected. A signal is sent to the display unit.

Further, the program of the present invention has a display unit provided with a backlight, and causes a processor provided in a portable telephone connectable to a network to perform processing for concealing a password displayed on the display unit. A program including a password input field for inputting a password on the display unit, and when the password input field is selected, a control signal for reducing the brightness of the backlight is displayed. It is sent to the display unit.

Further, the program of the present invention has a display unit provided with a liquid crystal screen, and causes a processor provided in a portable telephone connectable to a network to perform a process of concealing a password displayed on the display unit. A screen including a password input field for inputting a password on the display unit, and when the password input field is selected, a control signal for reducing the display density of the liquid crystal screen is displayed. It is sent to the display unit.

(Operation) In the present invention having the above configuration, when the password is input, the backlight provided on the display unit is turned off. Therefore, when the password is input to the password input field, the password displayed on the display unit is displayed. Visibility becomes worse. Therefore, the visibility of the password displayed on the display unit is ensured for the user, but the contents displayed on the display unit are difficult for others around the user to see.

In the present invention, when a password is input,
Since the brightness of the backlight provided on the display unit is weakened, when a password is input in the password input field, the visibility of the password displayed on the display unit is reduced. Therefore, it is difficult for others around the user to see the contents displayed on the display unit, and the user can sufficiently maintain the visibility of the password displayed on the display unit.

In the present invention, when a password is input,
Since the display density of the liquid crystal screen provided in the display unit is reduced, when a password is input in the password input field, the visibility of the password displayed on the display unit is further reduced. Therefore, the content displayed on the display unit becomes more difficult for others around the user to see.

Further, in the present invention, the backlight is made up of a plurality of light emitting diodes, and at the time of inputting a password, some of the light emitting diodes are turned off to reduce the brightness of the backlight. By turning on the other light emitting diodes except for the light emitting diode to be turned off, the visibility of the password displayed on the display unit is adjusted.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a portable telephone which can be connected to the Internet or the like. Can check the password displayed on the display screen, but it is characterized in that it is difficult for others around the user to see the contents of the display screen, thereby keeping the password confidential.

(First Embodiment) The first embodiment of the portable telephone according to the present invention.
An example will be described.

FIG. 1 is a block diagram showing one embodiment of the configuration of the portable telephone in the first embodiment.

The portable telephone of the present invention has an antenna 101
A radio unit 102 for transmitting and receiving radio waves to and from a mobile phone base station via an antenna 101; and an ear receiver 1 for outputting an audio signal based on data received from the radio unit 102
05 and a microphone 106 for capturing a user's voice
A display unit 107 for displaying image data received by the wireless unit 102; a wireless unit 102 and the ear receiver 10
5, a control unit 103 for controlling operations of the microphone 106 and the display unit 107, a memory unit 104 storing a control program, an operation unit 108 for inputting an instruction to the control unit 103, and power supply to each unit And a battery 109 serving as a main power supply for the power supply.

The control section 103 converts the user's voice input from the microphone 106 into a voice signal and outputs the voice signal to the radio section 102 as transmission data. Also, when receiving the received data from the wireless unit 102, the audio data is converted into audio and output to the ear receiver 105 as audio.
The image data is displayed on the display unit 107.

The control unit 103 has a processor.
A predetermined process is executed according to a control program stored in the memory unit 104.

Upon receiving radio waves from the mobile phone base station via antenna 101, radio section 102 amplifies and demodulates the received radio waves and sends the demodulated received data to control section 103. Further, upon receiving the transmission data from the control unit 103, the transmission data is modulated, converted to a frequency that propagates in space, amplified to a required power, and unnecessary frequency components are removed, and then transmitted via the antenna 101. The radio wave of the data is transmitted to the mobile phone base station.

The memory unit 104 includes a radio unit 102, an ear receiver 105, a microphone 106, and a display unit 107.
A control program for controlling the operation of the control unit 103 and various data necessary for processing performed by the control unit 103 are stored.

The operation unit 108 includes a character input button for inputting a dial number and characters, a clear button for deleting input characters, a cursor key for moving a cursor, and a field and an instruction indicated by the cursor. It has a selection button and so on.

The display unit 107 displays, on the basis of a signal from the control unit 103, a screen indicating the state of the mobile phone, such as a standby state and a call state, and a dial number and characters input by the user operating the operation unit 108. indicate. Display 107
For example, a liquid crystal display device provided with a backlight is used. Since the liquid crystal screen does not emit light by itself, a backlight illuminates the liquid crystal screen from the back and side surfaces so that the contents displayed on the liquid crystal screen can be easily seen by a user. A backlight lighting circuit is connected to the backlight, and turning on and off of the backlight is controlled by a control signal input from the control unit 103 to the backlight lighting circuit.

Next, the backlight lighting circuit will be described in detail.

FIG. 2 is a circuit diagram showing a configuration of a backlight lighting circuit for operating a backlight provided in the display unit 107 of this embodiment. Although two light emitting diodes are shown in FIG. 2, the number is not limited.

As shown in FIG. 2, the backlight lighting circuit includes a power supply (Vdd) connected to the battery 109.
201 and a resistor 202 connected to the power supply unit 201
And light emitting diodes 203 and 204 as backlights
FE with ON / OFF switch function connected to
T205.

The light emitting diodes 203 and 204 are connected in parallel, the plus terminals of the light emitting diodes 203 and 204 are connected to the resistor 202, and the minus terminals are connected to the FET 20.
5 D (drain).

The operation of the above-described backlight lighting circuit will be described.

When the lighting of the backlight is instructed by the control signal EN1 from the control unit 103, the D
−S (source) conducts, and the light emitting diodes 203 and 2
04 emits light because current is supplied from the power supply unit 201 via the resistor 202.

On the other hand, when the turning off of the backlight is instructed by the control signal EN1, the space between the DS and the FET 205 is opened, and the light emitting diodes 203 and 204 cannot receive the current supply from the power supply unit 201. To stop.

In this embodiment, when the user operates the operation unit 108 while looking at the display unit 107, the backlight is turned on as described above, and the contents displayed on the liquid crystal screen of the display unit 107 are changed. Make it easier for users to see. When the user operates the operation unit 108 to input a password while looking at the display unit 107, the backlight is turned off as described above, and the user can see the contents displayed on the liquid crystal screen. It is hard to see for others around the user.

Next, an operation procedure of the portable telephone having the above configuration will be described.

FIG. 3 is a flowchart showing the operation procedure of the control unit 103 in the content display processing.

As shown in FIG. 3, the user operates the operation unit 108.
Is operated to request the control unit 103 to connect to the Internet, the control unit 103 performs an operation of connecting to the Internet (S301), and obtains reception data of the specified homepage via the wireless unit 102 and the antenna 101 (S301). S302). The control unit 103 analyzes the received data of the specified home page described in a home page-specific language such as HTML (S303), and displays the screen display data of the analysis result on the display unit 107 (S30).
4).

Here, the login screen of the home page displayed on the display unit 107 will be described.

FIG. 4 is a view showing an example of a homepage login screen displayed on the display unit 107.

As shown in FIG. 4, an area 701 of the login screen includes a character area written in text and an image area, and the character area describes a description of a page. The user can see characters and images in the area 701 on the screen of the display unit 107.

The link 702 is for accessing a page different from the currently displayed page. Generally, when a link is set, an underline is displayed in a character string indicating the link destination. When the user selects the link 702, the page specified by the link is displayed on the display unit 107.

In the character input field 703, the user I
There are a D input field 704 and a password input field 705, which are fields used for character input.

When the user operates the operation unit 108 to select the character input field 703, the character input field 7
03 is in a state where characters can be input. Operation unit 1
When a character is input to the character input field 703 by operating 08, and the input is completed, the display unit 107 returns to the screen shown in FIG. 4 with the character input to the character input field 703.

The login screen as described above is displayed on the display unit 107.
After that, as shown in FIG. 3, the control unit 103
It is determined whether or not there is an instruction from the user to terminate the Internet connection via the operation unit 108 (S305). When the user inputs an instruction to end the Internet connection, the control unit 103 performs an operation of disconnecting from the Internet,
All operations end.

If there is no instruction to end the Internet connection from the user, the control section 103 determines which of the character input field 703 and the link 702 the user has selected (S306). When the user selects the link 702 displayed in the page, the control unit 103 proceeds to step S3
02, the data of the newly designated home page is acquired and displayed on the display unit 107.

When the user selects the character input field 703, the control unit 103 determines the type of the selected character input field 703 (S307). When the type of the character input field 703 selected by the user is the password input field 705, the control unit 103 performs a password input process (S308). This password input processing will be described later in detail.

Character input field 70 selected by user
If the third type is the user ID input field 704, the control unit 103 writes a character input by the user via the operation unit 108 into the user ID input field 704 (S309). When the input to the character input field 703 is completed, the control unit 103 waits for an input from the user.

Next, the operation procedure of the password input process in step S308 will be described.

FIG. 5 is a flowchart showing an operation procedure of the control unit 103 in the password input processing.

When the user selects the password input field 705 in step S307 shown in FIG. 3, the control unit 103 switches the password input field 705 to a state where characters can be input (S401), and controls the backlight at the time of password input. The operation starts (S402). As shown in FIG. 2, the start operation of the backlight control is based on the control signal EN1 from the control unit 103 and the FET2.
05 is turned off, and the light emission of the light emitting diodes 203 and 204 is stopped. By stopping the light emission of the light emitting diodes 203 and 204, the liquid crystal screen of the display unit 107 becomes dark, and the visibility of the liquid crystal screen deteriorates.

The control section 103 determines whether or not there is a character input (S403). If there is a character input, the inputted character is displayed on the display section 107 (S404). Usually, the password is four digits or more, so the control unit 1
In step 03, the process of step S404 is repeated until a signal indicating the end of password input is received from the operation unit 108.

The password to be entered is a four-digit “abc”
Assuming that the character is "d", the user inputs characters "a", "b", "c", and "d" sequentially from the operation unit 108 to determine the character. a "," a
"b", "abc", and "abcd" are sequentially displayed.
Here, since the backlight of the display unit 107 is turned off, the displayed characters are difficult to see,
Since the user is not in a state where no character is visible, the user can confirm the character of the input password.

Therefore, the user can recognize the mistake of the input character by looking at the display unit 107 even if the character is erroneously input, and can erase the erroneously input character by pressing the clear button provided on the operation unit 108. It is possible.

When the user finishes inputting the four-digit password, the control unit 103 receives a password input end signal from the operation unit 108 (S405), and displays the page screen shown in FIG. (S406), “****” is displayed in the password input field 705 (S407), and the backlight control operation at the time of inputting the password is ended (S408). In FIG. 2, the control signal EN1 from the control unit 103 turns on the FET 205 to cause the light emitting diodes 203 and 204 to emit light. The liquid crystal screen of the display unit 107 becomes bright, and the visibility of the liquid crystal screen is improved.

In this embodiment, when a password is input for personal authentication, the backlight of the display unit is turned off and the visibility of the display unit is switched to allow the user to input the password displayed on the display unit. In addition to being able to confirm the password, it is difficult for other persons around the user to see the contents displayed on the display unit, and the confidentiality of the password can be maintained.

(Second Embodiment) A second embodiment of the present invention will be described.

In the first embodiment, when the screen shifts to the password input screen, all the light emitting diodes which are the light sources of the backlight provided in the display unit 107 are turned off.
In this embodiment, the brightness of the backlight at the time of inputting the password is adjusted so that the user can see the liquid crystal screen even in darkness.

The backlight lighting circuit of this embodiment will be described. Since the configuration other than the backlight lighting circuit is the same as that of the first embodiment, a detailed description thereof will be omitted.

FIG. 6 is a circuit diagram showing a backlight lighting circuit according to the second embodiment.

As shown in FIG. 6, the backlight lighting circuit includes a power supply (Vdd) connected to the battery 109.
501 and a resistor 502 connected to the power supply unit 501
And light emitting diodes 503 and 504 as backlights
FE with ON / OFF switch function connected to
T505 and 506.

The light emitting diodes 503 and 504 are connected in parallel, and the plus terminals of the light emitting diodes 503 and 504 are connected to the resistor 502. Light emitting diode 503
Is connected to D (drain) of the FET 505, and the negative terminal of the light emitting diode 504 is FE.
It is connected to D of T506.

With the above configuration, the FETs 505 and 506 can be individually turned on / off by the control signals EN1 and EN2 from the control unit 103. Therefore,
The light emitting diodes 503 and 504 can also be individually turned on / off. During normal operation, the light emitting diodes 505 and 506 are controlled so as to light up.

Next, the operation procedure of the backlight of the backlight lighting circuit having the above configuration will be described with reference to the flowchart of the password input processing shown in FIG.

As a start operation of the backlight control in step S402 shown in FIG.
T505 is turned on to turn on the light emitting diode 503, but the control signal EN2 turns off the FET 506 to turn off the light emitting diode 504, thereby weakening the brightness of the backlight.

As an operation of ending the backlight control in step S408, the light emitting diode 503 is kept lit, and the FET 506 is turned on by the control signal EN2.
Then, the light emitting diode 506 is turned on.

By controlling as described above, one of the light emitting diodes 503 is turned on when a password is input,
Even in the dark, the user can confirm the password displayed on the display unit, and by turning off the other light emitting diode 504 to reduce the brightness of the backlight, other users around the user can be checked. It is difficult for a person to see the contents displayed on the display unit.

In this embodiment, when a password is input, the brightness of the backlight provided on the display unit is adjusted so that the user can view the contents displayed on the display unit even in darkness. By securing, compared to the first embodiment,
The user can easily see the password displayed on the display unit.

In the present embodiment, two light emitting diodes are used as a backlight for adjusting the brightness, but the number is not limited.

(Third Embodiment) A third embodiment of the present invention will be described.

In the first embodiment, the backlight lighting control is performed to reduce the visibility of the liquid crystal screen at the time of inputting the password. In this embodiment, however, the use of the liquid crystal screen is changed by changing the display density. This ensures the visibility of the password displayed on the display unit for the user, and makes it more difficult for others around the user to see the contents displayed on the display unit.

The configuration of this embodiment will be described. In addition,
In the present embodiment, except for the configuration for changing the display density of the liquid crystal screen, except for the backlight lighting control at the time of inputting the password in the first embodiment or the second embodiment, the first embodiment or the second embodiment. Therefore, the detailed description is omitted.

The memory unit 104 stores the density setting value X in the normal operation and the density setting value Y when the display density is lower than the density setting value X for the display density of the liquid crystal screen of the display unit 107. are doing.

Upon receiving from the operation unit 108 a signal indicating that the user selects the password input field 705, the control unit 103 sets the density setting value Y when the display density becomes low.
Is read from the memory unit 104, and a control signal for setting the density setting value to Y is sent to the display unit 107, so that the display density of the liquid crystal screen is made lower than usual. If the background of the displayed character is colorless, setting the density setting value to Y reduces the display density, making it difficult to distinguish the background from the liquid crystal screen from the character, and lowering the visibility of the character.

The operation procedure of the password input processing by the portable telephone having the above configuration will be described.

FIG. 7 is a flowchart showing a password input process in the third embodiment. In addition, the first
Since the difference from the first embodiment is the processing of steps S402 and S408 shown in FIG. 5, only the differences from the first embodiment will be described below.

As shown in FIG. 7, in the present embodiment, instead of the backlight control in steps S402 and S408 shown in FIG. 4, the display density of the liquid crystal screen is changed as follows.

When the control unit 103 receives a signal indicating that the user selects the password input field 705 from the operation unit 108, the control unit 103 sets the password input field 705 to a state where characters can be input (S601), and the memory unit 104
, And a control signal for setting the density setting value to Y is sent to the display unit 107 to reduce the display density (S602). When the displayed characters become thin, it becomes difficult to distinguish them from the background of the liquid crystal screen. In this state, the user inputs a password, and when the input of the password is completed, the control unit 103 receives an instruction to end the password input and displays a control signal for returning the density setting value to X on the display unit 10.
7 to make the characters displayed on the liquid crystal screen easy to see (S608).

In this embodiment, the user can confirm the characters displayed on the display unit by changing the display density of the liquid crystal screen when inputting the password. The contents displayed on the display unit are more difficult for others around.

In any of the first to third embodiments, the backlight is turned on when an operation other than the password input operation is performed, and the backlight is turned on after a lapse of a predetermined time after the user operation. Control is performed to turn off all lights, making it easy for the user to see the contents displayed on the display unit 107 and suppressing power consumption.

[0087]

Since the present invention is configured as described above, the following effects can be obtained.

In the password concealing method and the portable telephone according to the present invention, when the password is input, the input characters are displayed on the display unit to prevent erroneous input of the password, and the visibility of the display unit is adjusted. Although the characters displayed on the display unit can be confirmed by the user, it is difficult for others around the user to see the characters, and the confidentiality of the password is improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a configuration of a mobile phone according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a configuration of a backlight lighting circuit for operating a backlight in the first embodiment of the present invention.

FIG. 3 is a diagram showing a flowchart of a content display process according to the first embodiment of the present invention.

FIG. 4 is a diagram showing an example of a homepage login screen in the first embodiment of the present invention.

FIG. 5 is a diagram showing a flowchart of a password input process in the first embodiment of the present invention.

FIG. 6 is a circuit diagram showing a configuration of a backlight lighting circuit for operating a backlight according to a second embodiment of the present invention.

FIG. 7 is a diagram illustrating a flowchart of a password input process according to a third embodiment of the present invention.

[Explanation of symbols]

101 antenna 102 Radio section 103 control unit 104 Memory section 105 ear receiver 106 microphone 107 Display 108 Operation unit 109 Battery 201, 501 power supply 202, 502 resistance 203, 204, 503, 504 Light emitting diode 205, 505, 506 FET

Claims (10)

[Claims] 1. A password concealing method having a display unit provided with a backlight and inputting a password to a mobile phone connectable to a network, wherein a password is input to the display unit for inputting a password. A password concealing method, comprising displaying a screen including a field, and turning off the backlight when the password input field is selected. 2. A method for concealing a password when a password is input to a mobile phone connectable to a network, comprising a display unit having a backlight, wherein a password is input to the display unit for inputting a password. A password concealing method, comprising: displaying a screen including a field; and, when the password input field is selected, reducing the brightness of the backlight. 3. A method for concealing a password when a password is input to a mobile phone connectable to a network, comprising a display unit having a liquid crystal screen, wherein a password is input to the display unit for inputting a password. A password concealing method, comprising: displaying a screen including a field; and, when the password input field is selected, reducing the display density of the liquid crystal screen. 4. A mobile phone connectable to a network, comprising: a display unit having a backlight; and a screen including a password input field for inputting a password on the display unit, wherein the password input field is displayed. When selected, a control unit that sends a control signal for turning off the backlight to the display unit,
A mobile phone comprising: 5. A mobile phone connectable to a network, comprising: a display unit having a backlight; a backlight lighting circuit for adjusting brightness of the backlight in a stepwise manner; A control unit that displays a screen including a password input field for inputting a password, and when the password input field is selected, sends a control signal for reducing the brightness of the backlight to the backlight lighting circuit. A mobile phone comprising: 6. The mobile phone according to claim 5, wherein the backlight has a plurality of light emitting diodes, and the backlight lighting circuit is an on / off switch of the light emitting diodes connected to each of the light emitting diodes. The mobile phone according to claim 1, wherein the control unit outputs a control signal for turning off some of the FETs. 7. A mobile phone connectable to a network, comprising: a display unit having a liquid crystal screen; a memory unit for storing a density setting value for lowering a display density of the liquid crystal screen than usual; A screen including a password input field for inputting a password is displayed on the unit, and when the password input field is selected, the density setting value is read from the memory unit, and a control signal for setting the read density setting value is read. And a control unit that sends the control signal to the display unit. 8. A program that has a display unit provided with a backlight and causes a processor provided in a mobile phone connectable to a network to perform a process of concealing a password displayed on the display unit, A program for displaying a screen including a password input field for inputting a password on the display unit, and transmitting a control signal for turning off the backlight to the display unit when the password input field is selected. . 9. A program that has a display unit provided with a backlight and causes a processor provided in a mobile phone connectable to a network to perform a process of concealing a password displayed on the display unit, A screen including a password input field for inputting a password is displayed on the display unit, and when the password input field is selected, a control signal for weakening the brightness of the backlight is transmitted to the display unit. Program for. 10. A program that has a display unit provided with a liquid crystal screen and causes a processor provided in a mobile phone connectable to a network to perform a process of concealing a password displayed on the display unit. A screen including a password input field for inputting a password is displayed on the display unit. When the password input field is selected, a control signal for reducing the display density of the liquid crystal screen is transmitted to the display unit. Program for.