Mobile terminal provided with display controlling function by detecting insertion of earphone jack

When a power source is turned on, a menu screen is displayed on LCD. When the insertion of an earphone jack is detected with the menu screen displayed, display on LCD is automatically switched from the menu screen to a dialing screen. A user can have conversation with a desired party by dialing using the displayed dialing screen. If the insertion of an earphone jack is detected while another processing is executed using the menu screen after the power source is turned on, the processing is temporarily interrupted and the dialing screen is displayed on LCD. The temporarily interrupted processing is executed again when a call is finished. Even during a call, another processing can be executed using the menu screen.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to a mobile terminal provided with a radio
 telephone function.
 2. Description of the Related Art
 Recently, a mobile terminal provided with a communication function such as
 a telephone and data communication, and so on, is widely popular. For a
 general mobile terminal provided with a telephone function, to solve a
 problem of large size caused by providing dial keys with which a normal
 telephone set is provided, a touch-panel is adopted. Therefore, if a user
 uses a telephone function, a dial screen is displayed on a liquid-crystal
 display (LCD) when the user presses a predetermined switch. The user can
 make a call and others by pressing each touch tone dial on the displayed
 dial screen.
 However, for such a mobile terminal, if such a mobile terminal is put in a
 bag or a pocket with a dial screen displayed on LCD, there is a problem
 that a key is pressed by mistake and a call is made.
 In a radio telephone disclosed in Japanese laid-open patent application
 heisei4-192850, calling operation is limited based upon whether an
 earphone jack is inserted or not. Therefore, in such a radio telephone, if
 the mobile telephone is put in a bag or a pocket, a call is prevented from
 being made when a user detaches an earphone jack from the mobile terminal
 even if a key is pressed by mistake.
 However, such a radio telephone has a problem that operability is
 deteriorated because predetermined key operation is required to make a
 call after the insertion of the earphone jack.
 SUMMARY OF THE INVENTION
 The object of the present invention is to provide a mobile terminal
 obtained by further improving a conventional type mobile terminal.
 Another object of the present invention is to provide a mobile terminal in
 which operability is enhanced by automatically displaying a dialing screen
 if an earphone jack is inserted into the mobile terminal.
 Further another object of the present invention is to provide a mobile
 terminal the flexibility of which is enhanced by enabling even a user who
 does not know a method of operating the mobile terminal at all to readily
 use the mobile terminal as a telephone set.
 Furthermore another object of the present invention is to provide a mobile
 terminal in which operation for users to communicate can be promptly
 executed by automatically displaying a dialing screen if a protective
 cover is opened with an earphone jack inserted into the mobile terminal.
 The other object of the present invention is to provide a mobile terminal
 in which a call is automatically finished if an earphone jack is pulled
 out of the mobile terminal and a user can do the next processing promptly
 by making a menu screen display.
 To achieve the above objects, a mobile terminal according to the present
 invention is provided with display means for displaying a menu screen,
 detection means for detecting the insertion of an earphone jack and
 control means for switching said menu screen to a dialing screen for
 executing a telephone function based upon the output of said detection
 means. The mobile terminal according to the present invention is also
 provided with communication means for enabling communication using a
 telephone function. The display means displays a dialing screen. The
 control means controls the above display means so that the above menu
 screen is switched to the above dialing screen if the insertion of an
 earphone jack is detected. It is desirable that the dialing screen is a
 ten key screen or an address book screen. The mobile terminal according to
 the present invention is also provided with selection means for selecting
 either the ten key screen or the address book screen. The mobile terminal
 according to the present invention is further provided with judgment means
 for judging whether the mobile terminal exists inside a receivable area or
 not and the display means displays a predetermined warning message if the
 insertion of an earphone jack is detected when it is judged that the
 mobile terminal does not exist inside a receivable area. The mobile
 terminal according to the present invention is also provided with
 comparison means for comparing the voltage value of a cell for driving the
 mobile terminal with a predetermined value and the display means displays
 a predetermined warning message if the insertion of an earphone jack is
 detected when the voltage value of the cell is smaller than a
 predetermined value. The mobile terminal according to the present
 invention is also provided with operation means for operating so that
 functions except the above telephone function are executed. The mobile
 terminal according to the present invention is also provided with
 interruption means for interrupting the execution of a function except the
 telephone function if the insertion of an earphone jack is detected when
 the function except the telephone function is executed. The mobile
 terminal according to the present invention is also provided with
 resumption means for resuming the execution of the function interrupted by
 the interruption means after a call is finished. The mobile terminal
 according to the present invention is provided with judgment means for
 judging whether an earphone jack is pulled out or not during a call and
 ring-off processing means for executing the ring-off processing of the
 call based upon the output of the above judgment means. The control means
 controls the display means based upon the output of the judgment means.
 The mobile terminal according to the present invention is further provided
 with judgment means for judging whether a protective cover for protecting
 the display means is open or not. The control means controls the display
 means based upon the output of the detection means and the judgment means.
 The display means displays a dialing screen if a protective cover is
 opened with an earphone jack inserted. The mobile terminal according to
 the present invention is also provided with judgment means for judging
 whether the mobile terminal exists in a receivable area or not if an
 earphone jack is inserted with a protective cover closed. The display
 means displays a predetermined warning message if it is judged by the
 above judgment means that the mobile terminal does not exist in a
 receivable area. The mobile terminal according to the present invention is
 also provided with judgment means for judging whether an earphone jack is
 pulled out during a call or not. The mobile terminal according to the
 present invention is also provided with ring-off processing means for
 executing the ring-off processing of the call based upon the output of the
 above judgment means. The control means controls the display means based
 upon the output of the above judgment means.
 Also, the mobile terminal according to the present invention is provided
 with LCD for displaying a menu screen, earphone jack insertion detecting
 means for detecting the insertion of an earphone jack and CPU for
 switching menu screen to a dialing screen for executing a telephone
 function based upon the output of earphone jack insertion detecting means.
 The mobile terminal according to the present invention is also provided
 with a protective cover opening/closing detecting section for judging
 whether a protective cover for protecting the LCD is open or not.
 A display control method of the mobile terminal according to the present
 invention is provided with a step for turning on a power source, a step
 for displaying a menu screen, a step for detecting the insertion of an
 earphone jack and a step for switching the above menu screen to a dialing
 screen for executing a telephone function based upon detection in the
 detection step. The display control method is also provided with a step
 for judging whether the mobile terminal exists inside a receivable area or
 not, a step for displaying information showing whether the mobile terminal
 exists inside a receivable area or not and a step for displaying a
 predetermined warning message if an earphone jack is inserted when the
 mobile terminal exists outside the receivable area. The display control
 method is also provided with a step for comparing the voltage value of a
 cell built in the mobile terminal with a predetermined value and a step
 for displaying a predetermined warning message if the voltage value of the
 cell is smaller than the predetermined value. The display control method
 is also provided with a step for inputting a dial and a step for having
 conversation. The display control method is also provided with a step for
 operating so that another function different from the telephone function
 is executed, a step for executing the function based upon the above
 operation and a step for interrupting the execution of the function if an
 earphone jack is inserted while the function based upon the operation is
 executed. The display control method is also provided with a step for
 resuming the interrupted execution of the function when a call is
 finished. The display control method is also provided with a step for
 judging whether a protective cover is open or not and a step for
 displaying a dialing screen when the protective cover is opened if an
 earphone jack is inserted with the protective cover closed. The display
 control method is also provided with a step for judging whether the mobile
 terminal exists in a receivable area or not and a step for displaying a
 predetermined warning message when the mobile terminal does not exist in a
 receivable area and a protective cover is opened. The display control
 method is also provided with a step for detecting the extraction of an
 earphone jack and a step for switching a dialing screen to a menu screen
 based upon detection in the above extraction detecting step. The display
 control method is also provided with a step for detecting the extraction
 of an earphone jack and a step for terminating a call based upon the
 detection in the extraction detecting step.
 Therefore, according to the present invention, predetermined operation for
 switching a menu screen to a dialing screen is not required because the
 dialing screen is automatically displayed by inserting an earphone jack
 into a mobile terminal and operability can be enhanced.
 Also, according to the present invention, flexibility can be enhanced
 because even a user who does not know a method of operating a mobile
 terminal at all can use it as a telephone set only by inserting an
 earphone jack into the mobile terminal.
 Also, according to the present invention, a user can promptly perform
 operation for making a call because a dialing screen is automatically
 displayed when a protective cover is opened with an earphone jack inserted
 into a mobile terminal.
 Further, according to the present invention, a user is not required to
 perform any operation for displaying a menu screen after a call is
 terminated and can promptly perform the next processing because a call is
 automatically terminated and a menu screen is displayed if an earphone
 jack is extracted from a mobile terminal.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
 Referring to FIG. 1, the configuration of a suitable example of a mobile
 terminal according to the present invention will be described below.
 As shown in FIG. 1, a sending/receiving section 2 receives a radio signal
 from a base station not shown via an antenna 1, while it sends a radio
 signal to a base station not shown via the antenna 1 under the control of
 CPU 3. RAM 4 stores screen information displayed on LCD 8. ROM 5 stores
 various programs for controlling the mobile terminal. An earphone jack
 insertion detecting section 6 detects whether an earphone jack 10 is
 inserted into an earphone jack inserting part 9 or not. A Notification
 section 7 outputs a notification sound if a radio signal is received by
 the sending/receiving section 2 under the control of CPU 3. LCD 8 displays
 screen information stored in RAM 4 under the control of CPU 3. CPU 3
 controls the screen information displayed on LCD 8 when the insertion of
 an earphone jack is detected by the earphone jack insertion detecting
 section 6. A menu screen shown in FIG. 2 is normally displayed on LCD 8
 when a power source is turned on. When a user selects one of plural
 application programs displayed on the menu screen, for example, touches
 the icon, the selected application program is initialized. If a user
 touches a telephone icon, a ten key screen shown in FIG. 3 is displayed
 and the user can use it as a mobile telephone.
 FIG. 4 is a suitable outside drawing showing the mobile terminal shown in
 FIG. 1.
 As shown in FIG. 4, the earphone jack inserting part 9 is provided to the
 side of the body of the mobile terminal. The notification section 7 is not
 limited to a speaker and may be also a light emitting diode (LED) or a
 vibrator. A power source 17 is provided to the side of the mobile
 terminal. A user can turn on the power source by operating a power switch.
 FIG. 5 shows a state when the mobile terminal shown in FIG. 4 is used.
 As shown in FIG. 5, if the mobile terminal is used as a telephone set, a
 user can catch the voice of the other party by inserting one end of the
 earphone jack 10 into the earphone jack inserting part 9 of the body of
 the mobile terminal and putting the other end of the earphone jack 10 in
 either ear of the user.
 Next, referring to FIGS. 6a to 6c, the operation of a suitable example of
 the mobile terminal shown in FIG. 1 will be described in detail.
 As shown in FIG. 6a, when the power source is turned on (YES in a step
 101), a menu screen is displayed on LCD 8 in a step 102. Afterward, it is
 judged in a step 103 whether the mobile terminal exists in a receivable
 area or not.
 If it is judged that the mobile terminal does not exist in the receivable
 area, that is, if it is judged that the mobile terminal exists outside the
 receivable area (NO in the step 103), a mark for showing that the mobile
 terminal exists outside the receivable area is displayed on LCD 8 as shown
 in FIG. 6b in a step 122. Afterward, it is judged in a step 123 whether a
 user operates to select an application program on the menu screen or not,
 for example touches an icon or not. If the user does not operate to select
 an application program on the menu screen (NO in the step 123), it is
 judged in a step 124 whether the earphone jack 10 is inserted into the
 earphone jack inserting part 9 or not. If the earphone jack 10 is inserted
 into the earphone jack inserting part 9 (YES in the step 124), a sentence
 for caution, for example "You cannot receive call outside area" is
 displayed on LCD 8 in a step 125. Afterward, it is judged in a step 130
 whether the power source is turned off or not and if the power source is
 not turned off (NO in the step 130), the display on LCD 8 is switched from
 the sentence for caution to a menu screen in the step 102.
 On the other hand, if a user operates to select an application program on
 the menu screen (YES in the step 123), the selected application program is
 initialized on LCD 8 and is executed in a step 126. It is judged in a step
 127 whether the earphone jack 10 is inserted into the earphone jack
 inserting part 9 or not. If the earphone jack 10 is inserted into the
 earphone jack inserting part 9 (YES in the step 127), the sentence for
 caution, for example "You cannot receive call outside area" is displayed
 on LCD 8 in a step 128. Afterward, it is judged in a step 129 whether the
 execution of the selected application program is finished or not and if
 the execution of the selected application program is not finished (NO in
 the step 129), the execution of the selected application program is
 continued in the step 126. If the execution of the selected application
 program is finished (YES in the step 129), the screen of the selected
 application program is deleted and it is judged in a step 130 whether the
 power source is turned off or not. If the power source is not turned off
 (NO in the step 130), a menu screen is displayed on the step 102.
 If it is judged (YES in the step 103 shown in FIG. 6a) that the mobile
 terminal exists in a receivable area, a mark showing that the mobile
 terminal exists in the receivable area is displayed on LCD 8 in a step
 104. It is judged in a step 105 whether a user operates to select an
 application program on the menu screen or not, for example touches an icon
 or not.
 If the user operates to select the application program on the menu screen
 (YES in the step 105), the selected application program is initialized on
 LCD 8 as shown in FIG. 6c and is executed based upon the operation of the
 user in a step 131. It is judged in a step 132 whether the earphone jack
 10 is inserted into the earphone jack inserting part 9 or not. If the
 earphone jack 10 is not inserted into the earphone jack inserting part 9
 (NO in the step 132), it is judged in a step 136 whether the execution of
 the selected application program is finished or not and if the execution
 of the selected application program is not finished (NO in the step 136),
 it is continued in the step 131. If the execution of the selected
 application program is finished (YES in the step 136), it is judged in a
 step 137 whether the power source is turned off or not and if the power
 source is not turned off (NO in the step 137), the display on LCD 8 is
 switched from the sentence for caution to a menu screen in the step 102.
 If it is judged (YES in the step 132) that the earphone jack 10 is inserted
 into the earphone jack inserting part 9, it is judged in a step 133
 whether the voltage value of a cell built in the mobile terminal and not
 shown is higher than a predetermined value or not. The above predetermined
 value shows the lowest voltage value at which a telephone function can be
 used and if a lithium ion cell is built, the predetermined value is preset
 to 3.6 V for example. If it is judged (NO in the step 133) that the
 voltage value of the cell is a predetermined value or lower, a sentence
 for caution, for example "Charge" is displayed on LCD 8 in a step 135.
 Afterward, it is judged in a step 136 whether the execution of the
 selected application program is finished or not and it is judged in a step
 137 whether the power source is turned off or not.
 If it is judged (YES in the step 133) that the voltage value of the cell is
 larger than the predetermined value, the application program being
 executed is interrupted in a step 134 and the ten key screen shown in FIG.
 3 is displayed on LCD 8 in a step 109.
 If a user does not operate to select an application program on a menu
 screen (NO in the step 105 shown in FIG. 6a), it is judged in a step 106
 whether the earphone jack 10 is inserted into the earphone jack inserting
 part 9 or not. If the earphone jack 10 is not inserted into the earphone
 jack inserting part 9 (NO in the step 106), the menu screen is continued
 to be displayed in the step 102.
 If the earphone jack 10 is inserted into the earphone jack inserting part
 9, it is judged in a step 108 whether the voltage value of a cell built in
 the mobile terminal and not shown is higher than a predetermined value or
 not. The above predetermined value is the same as the predetermined value
 described in the step 133 in FIG. 6c. If it is judged (NO in the step 108)
 that the voltage value of the cell is a predetermined value or lower, the
 sentence for caution, for example "Charge" is displayed on LCD 8 in a step
 107. Afterward, when predetermined time elapses, a menu screen is
 displayed on LCD 8 again in the step 102.
 If it is judged (YES in the step 108) that the voltage value of the cell is
 larger than a predetermined value, a ten key screen stored in RAM 4 is
 displayed on LCD 8 in the step 109. Screen information stored in RAM 4 is
 not limited to the ten key screen. A method of storing screen information
 in RAM 4 will be described in detail later.
 Next, it is judged in a step 110 whether a user dials on the ten key screen
 displayed on LCD 8 or not, for example whether a user touches a desired
 number or not. If the user does not dial (NO in the step 110), it is
 judged in a step 111 whether the earphone jack 10 is inserted or not. If
 the earphone jack 10 is not inserted (NO in the step 111), a menu screen
 is displayed on LCD 8 again in the step 102. If the earphone jack 10 is
 inserted (YES in the step 111), the ten key screen is displayed as it is
 in the step 109.
 If a user dials (YES in the step 110), it is judged in a step 112 whether a
 call to the other party corresponding to the dialed number is received or
 not. If the call is not received (NO in the step 112), it is judged in a
 step 113 whether the call is made or not. If it is judged (NO in the step
 113) that no call is made, it is judged that the call was not received and
 a sentence for caution, for example "Your call cannot be received" is
 displayed on LCD 8 in a step 138. Afterward, when a predetermined time
 elapses (YES in a step 139), a ten key screen is displayed on LCD 8 again
 in the step 109. On the other hand, if a call is received (YES in the step
 112), the user and the other party have conversation in a step 114. During
 a call, it is judged in a step 115 whether a user switches a screen
 displayed on LCD 8 from the dialing screen to a menu screen and operates
 to select an application program on the menu screen or not, for example
 touches an icon or not. If the user does not operate to select an
 application program on the menu screen (NO in the step 115), it is judged
 in a step 119 whether the call is finished or not.
 On the other hand, if the user operates to select an application program on
 the menu screen (YES in the step 115), the selected application program is
 initialized on LCD 8 and is executed based upon the operation by the user
 in a step 116. It is judged in a step 117 whether the call is finished or
 not and it is judged in a step 118 whether the execution of the selected
 application program is finished or not. If the call is finished (YES in
 the step 117) and the execution of the selected application program is
 finished (YES in the step 118) or if the call is finished without a user
 operating to select an application program on a menu screen during the
 call (YES in the step 119), it is judged in a step 120 whether there is an
 application program interrupted before the call or not as described in the
 step 134 shown in FIG. 6c. If there is the interrupted application program
 (YES in the step 120), each processing shown in FIG. 6c is executed.
 If there is no application program interrupted before the call (NO in the
 step 120), it is judged in a step 121 whether the earphone jack 10 is
 inserted into the earphone jack inserting part 9 or not. If the earphone
 jack 10 is inserted (YES in the step 121), processing after the step 109
 is executed again. If the earphone jack 10 is not inserted (NO in the step
 121), processing after the step 102 is executed again.
 For a dialing screen, an address book screen shown in FIG. 7 is also
 conceivable in addition to the ten key screen shown in FIG. 3.
 As shown in FIG. 7, the name of the other party registered by a user
 beforehand, the name and the phone number of a company to which the other
 party belongs are displayed on the address book screen. When a user
 selects the other party to be called on the address book screen, the ten
 key screen shown in FIG. 3 is displayed on LCD 8 and connection to the
 other party selected is automatically started. A call is terminated by a
 user pressing a call terminating button on the ten key screen.
 A user can set a screen displayed when the earphone jack 10 is inserted.
 For example, a user can preset which of the ten key screen and the address
 book screen is to be displayed on LCD 8.
 FIG. 8 is a flowchart showing the details of a method of initializing a
 screen automatically displayed if the earphone jack 10 is inserted.
 As shown in FIG. 8, when the power source is turned on (YES in a step 201),
 a menu screen is displayed on LCD 8 in a step 202. It is judged in a step
 203 whether a user operates to select a dialing screen on the menu screen
 with the menu screen displayed or not. If the user does not operate to
 select the dialing screen on the menu screen (NO in the step 203), the
 menu screen is displayed as it is in the step 202.
 If the user operates to select the dialing screen on the menu screen (YES
 in the step 203), it is judged in steps 204 and 206 which of a ten key
 screen and an address book screen is selected. If the ten key screen is
 selected, it is registered in RAM 4 in a step 205 and if the address book
 screen is selected, it is registered in RAM 4 in a step 207. When the
 screen is registered in RAM 4, a menu screen is displayed on LCD 8 again
 in the step 202. If neither the ten key screen nor the address book screen
 is selected, it is judged in a step 208 whether predetermined time, for
 example ten seconds elapse or not. When no screen is selected and
 predetermined time elapses, it is judged in a step 209 whether the power
 source is turned off or not and if the power source is not turned off (NO
 in the step 209), a menu screen is displayed again in the step 202.
 Next, referring to FIGS. 9a and 9b, the configuration of a suitable example
 of the earphone jack insertion detecting section 6 shown in FIG. 1 will be
 described. FIG. 9a shows a state in which the earphone jack 10 is not
 inserted into the earphone jack inserting part 9 and FIG. 9b shows a state
 in which the earphone jack 10 is inserted into the earphone jack inserting
 part 9.
 As shown in FIG. 9a, as a terminal X does not come in contact with a
 terminal Y in a state in which the earphone jack 10 is not inserted, the
 voltage of the control section, for example 3 V, that is, a voltage value
 at a high level is output to CPU 3.
 FIG. 10a shows an equivalent circuit of the earphone jack insertion
 detecting section 6 if the earphone jack 10 is not inserted.
 As shown in FIG. 10a, as input impedance at the input terminal of CPU is
 high, voltage at a point Z is acquired based upon the ratio of the input
 impedance to a resistor R. However, as current hardly flows if input
 impedance is high, .DELTA.V.apprxeq.0 because I.apprxeq.0 based upon an
 expression .DELTA.V=I R showing voltage drop at the resistor R. Therefore,
 the voltage at the point Z is 3 V.
 On the other hand, as the terminal X is pressed by the earphone jack and
 comes in contact with the terminal Y in a state in which the earphone jack
 10 is inserted as shown in FIG. 9b, a voltage value at a ground level,
 that is, at a low level is output to CPU 3.
 FIGS. 10b and 10c respectively show an equivalent circuit of the earphone
 jack insertion detecting section 6 if the earphone jack 10 is inserted.
 As shown in FIG. 10b, as a smaller value of parallel resistance is
 dominant, an equivalent circuit shown in FIG. 10c is obtained. As voltage
 drop is finished at the point Z, voltage at the point Z is at a ground
 level.
 Therefore, CPU 3 can judge whether the earphone jack 10 is inserted into
 the earphone jack inserting part 9 or not depending upon that a voltage
 value output from the earphone jack insertion detecting section 6 is at a
 high level or at a low level.
 Next, referring to FIG. 11, the circuitry configuration of a mobile
 terminal equivalent to another embodiment of the present invention will be
 described.
 As shown in FIG. 11, the same reference number is allocated to the same
 component as in the mobile terminal shown in FIG. 1. The mobile terminal
 in this embodiment is newly provided with a protective cover
 opening/closing detecting section 12 in addition to the mobile terminal
 shown in FIG. 1 and provided with CPU 14 in place of CPU 3. The protective
 cover opening/closing detecting section 12 detects that a protective cover
 13 provided to protect LCD 8 is open or closed for the body of the mobile
 terminal. CPU 14 controls a screen displayed on LCD 8 based upon the
 output of the earphone jack insertion detecting section 6 and the output
 of the protective cover opening/closing detecting section 12.
 FIG. 12 is a suitable outside drawing showing the mobile terminal shown in
 FIG. 11.
 As shown in FIG. 12, LCD 8 is protected by closing the protective cover 13.
 The protective cover opening/closing detecting section 12 is composed of a
 switch 15 and a convex portion 16 for example. In this case, when the
 protective cover 13 is closed, the switch 15 is turned on by the convex
 portion 16. Therefore, CPU 14 can judge whether the protective cover 13 is
 closed or not based upon whether the switch 15 is turned on or not. At
 this time, the switch 15 and the convex portion 16 are required to be
 respectively provided in positions corresponding when the protective cover
 13 is closed.
 The protective cover opening/closing detecting section 12 may be also
 composed of a light receiving part 15 and a luminance level detecting part
 built in the mobile terminal and not shown. The luminance level detecting
 part detects a luminance level in the light receiving part 15. The
 luminance level detected by the luminance level detecting part is compared
 with a predetermined level. It is judged whether the protective cover 13
 is closed or not based upon whether a luminance level detected by the
 luminance level detecting part is higher than a predetermined level or
 not.
 The constitution of the protective cover opening/closing detecting section
 12 is not limited to the constitution of the switch 15 and the convex
 portion 16, and the constitution of the light receiving part 15 and the
 luminance level detecting part not shown.
 A power switch 18 is provided not only to the side of the mobile terminal
 but at the same level as LCD 8. As shown in FIG. 4, the power switch 18
 may be also provided only to the side of the mobile terminal. Therefore, a
 user can turn on a power source by operating the power switch 18 when the
 protective cover 13 is open or when the protective cover is closed.
 Next, referring to FIG. 13, the operation of a suitable example of the
 mobile terminal shown in FIG. 11 will be described in detail.
 As shown in FIG. 13, when the power source is turned on (YES in a step
 301), it is judged in a step 302 whether the protective cover 13 is open
 or not. If it is judged (YES in the step 302) that the protective cover 13
 is open, a menu screen is displayed on LCD 8 in a step 303. It is judged
 in a step 304 whether an earphone jack 10 is inserted into an earphone
 jack inserting part 9 or not. If the earphone jack 10 is not inserted into
 the earphone jack inserting part 9 (NO in the step 304), processing after
 the step 302 is executed again. On the other hand, if the earphone jack 10
 is inserted into the earphone jack inserting part 9 (YES in the step 304),
 a dialing screen shown in FIG. 3 is displayed on LCD 8 in a step 305. When
 a user dials on the dialing screen displayed on LCD 8 in a step 306, the
 user and the other party have conversation in a step 307. When the call is
 finished (YES in a step 308), it is judged in a step 309 whether the power
 source is turned off or not and if the power source is not turned off (NO
 in the step 309), processing after the step 302 is executed again.
 If it is judged that the protective cover 13 is closed (NO in the step
 302), it is judged in a step 310 whether the earphone jack 10 is inserted
 in the earphone jack inserting part 9 or not. If the earphone jack 10 is
 not inserted into the earphone jack inserting part 9 (NO in the step 310),
 it is judged in a step 315 whether the protective cover 13 is opened or
 not. If the protective cover 13 is opened (YES in the step 315), a menu
 screen is displayed and processing after the step 303 is executed. On the
 other hand, if the earphone jack 10 is inserted into the earphone jack
 inserting part 9 (YES in the step 310), it is judged in a step 311 whether
 a mobile terminal exists in a receivable area or not. If the mobile
 terminal exists in a receivable area (YES in the step 311), it is judged
 in a step 312 whether the protective cover 13 is opened or not. If the
 protective cover 13 is opened (YES in the step 312), a dialing screen is
 displayed on LCD 8 and processing after the step 305 is executed. On the
 other hand, if the mobile terminal does not exist in the receivable area
 (NO in the step 311), it is judged in a step 313 whether the protective
 cover 13 is opened or not. If the protective cover 13 is opened (YES in
 the step 313), a sentence for caution, for example "You cannot call" is
 displayed on LCD 8 and processing after the step 302 is executed again.
 Next, referring to FIG. 14, the operation of a suitable example of the
 mobile terminals shown in FIGS. 1 and 11 when the earphone jack is
 extracted will be described in detail.
 If another function is used during a call, a screen corresponding to the
 function is displayed on LCD 8. If no other function is used, the dialing
 screen is displayed as it is.
 First, during a call (a step 401), it is judged in a step 402 whether the
 earphone jack 10 is extracted or not. That is, it is judged whether the
 insertion of the earphone jack 10 is detected or not. If the earphone jack
 10 is extracted during the call (YES in the step 402), call terminating
 operation is automatically executed in a step 403 and the screen displayed
 on LCD 8 is automatically switched to a menu screen in a step 404.
 On the other hand, if the earphone jack 10 remains inserted during the call
 (NO in the step 402), it is judged in a step 405 whether a call
 terminating button is pressed or not. If the call terminating button is
 not pressed (NO in the step 405), processing in the step 402 is executed
 again. If the call terminating button is pressed (YES in the step 405),
 the call is finished and it is judged in a step 406 whether a termination
 button is pressed or not. If it is judged that the termination button is
 not pressed (NO in the step 406), it is judged in a step 407 whether the
 earphone jack 10 is extracted or not. If the earphone jack 10 remains
 inserted without pressing the termination button (NO in the step 407),
 processing in the step 406 is executed again.
 If the call is finished and the termination button is pressed (YES in the
 step 406) and if the earphone jack 10 is extracted without pressing the
 termination button (YES in the step 407), a menu screen is displayed on
 LCD 8 in a step 408.
 In this embodiment, for a dialing screen, a ten key screen and an address
 book screen are given as an example, however, the dialing screen is not
 limited to these screens. In short, the dialing screen has only to be a
 screen required in case a telephone function is used.
 As described above, according to the present invention, as a dialing screen
 is automatically displayed by inserting the earphone jack 10 into the
 mobile terminal, predetermined operation for switching a menu screen to a
 dialing screen is not required and operability can be enhanced.
 As even a user who does not know a method of operating the mobile terminal
 at all can use the mobile terminal as a telephone set only by inserting
 the earphone jack 10 into the mobile terminal, flexibility can be
 enhanced.
 As a dialing screen is automatically displayed when the protective cover 13
 is opened with the earphone jack 10 inserted in the mobile terminal, a
 user can operate promptly to make a call.
 Further, as a call is automatically finished and a menu screen is displayed
 if the earphone jack is extracted from the mobile terminal, a user is not
 required to perform any operation for displaying the menu screen after the
 call is finished and can perform the next processing promptly. obviously,
 numerous additional modifications and variations of the present invention
 are possible in light of the above teachings. It is, therefore, to be
 understood that within the scope of the appended claims, the invention may
 be practiced otherwise than as specifically described herein.