Mobile terminal having touch screen and method for displaying cursor thereof

A portable terminal including a touch screen and method for displaying a cursor thereof are provided. The method includes determining whether a capacitance is equal to or greater than a first critical value and is less than a second critical value, if the change of the capacitance is sensed in the touch screen, displaying a cursor in an area where the change of the capacitance is sensed, if the capacitance is equal to or greater than the first critical value and is less than the second critical value, and performing a function corresponding to the area where the cursor is displayed, if the capacitance sensed in the area where the cursor is displayed is equal to or greater than the second critical value.

PRIORITY

This application claims the benefit under 35 U.S.C. §119(a) of a Korean patent application filed in the Korean Intellectual Property Office on Jul. 28, 2008 and assigned Serial No. 10-2008-0073653, the entire disclosure of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a portable terminal including a touch screen and a method for displaying a cursor thereof. More particularly, the present invention relates to a portable terminal having a capacitive overlay type touch screen and a method for displaying a cursor according to a touch sensed in the portable terminal.

2. Description of the Related Art

A touch screen has an advantage in that an input unit and a display unit can be implemented through one apparatus, and the touch screen can be mounted on a small terminal, such as a portable terminal. Touch screens mounted on the portable terminal include a capacitive overlay type, a resistive overlay type, a surface acoustic wave type, a transmitter type and an infrared beam type. Among the various types of touch screens, the capacitive overlay type touch screen is commonly used for portable terminals.

The capacitive overlay type touch screen can detect an area where touch occurs through the change of capacitance which is generated when an object that is conductive, such as the body of a user or a stylus including a dielectric substance, comes into contact with the touch screen. The change of capacitance is in proportion to dimensions of the object that contacts the touch screen. Therefore, as the dimensions of the object which is sensed in the touch screen is increased, the area where the touch is sensed can be more accurately.

However, since the size of the touch screen is limited, a small terminal, such as the portable terminal, has a problem in that a user can misrecognize the area touched by the object in the capacitive overlay type touch screen as another area. Accordingly the portable terminal displays an undesired icon or location or the portable terminal malfunctions.

Therefore, a need exists for a portable terminal and a method for accurately determining an area touched on a capacitive overlay type touch screen of the portable terminal.

SUMMARY OF THE INVENTION

An aspect of the present invention is to address at least the above-mentioned problems and/or disadvantages and to provide at least the advantages described below. Accordingly, an aspect of the present invention is to provide a portable terminal including a capacitive overlay type touch screen and a method for displaying a cursor in the portable terminal.

In accordance with an aspect of the present invention, a method for displaying a cursor of a portable terminal including a capacitive overlay type touch screen is provided. The method includes determining whether a capacitance is equal to or greater than a first critical value and is less than a second critical value, if the change of the capacitance is sensed in the touch screen, displaying a cursor in an area where the change of the capacitance is sensed, if the capacitance is equal to or greater than the first critical value, and is less than the second critical value, and performing a function corresponding to the area where the cursor is displayed, if the capacitance sensed in the area where the cursor is displayed is equal to or greater than the second critical value.

In accordance with another aspect of the present invention, a portable terminal is provided. The portable terminal includes a touch screen including a touch sensor for sensing a change of capacitance, a display unit for displaying a cursor corresponding to the sensed capacitance, a storage for storing a first critical value and a second critical value for displaying the cursor corresponding to the capacitance, and a controller for determining whether the capacitance is equal to or greater than the first critical value and is less than the second critical value if the change of the capacitance is sensed in the touch screen, for controlling the touch screen to display the cursor in an area where the change of the capacitance is sensed if the capacitance is equal to or greater than the first critical value and is less than the second critical value, for determining whether the capacitance sensed in the area where the cursor is displayed is equal to or greater than the second critical value stored in the storage, and for performing a function corresponding to the area where the cursor is displayed.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1is a block diagram illustrating a schematic configuration of a portable terminal according to an exemplary embodiment of the present invention.FIGS. 2A and 2Bare graphs illustrating a change of capacitance of a touch screen according to an exemplary embodiment of the present invention.

Referring toFIG. 1, the portable terminal includes a touch screen110, a controller120and a storage unit130. The touch screen110includes a display unit115and a touch sensor117. The display unit115may display various data related to a state and an operation of the portable terminal. More particularly, if the display unit115, under control of the controller120, senses access to the touch screen110by an object, a cursor may be displayed in an area accessed where the object is sensed.

Accordingly, the user may confirm the area selected through the cursor displayed on the display unit115. Here, the cursor may be displayed with a type of highlight or a type of block. According to a change of capacitance which is sensed in the given area of the touch screen110under the control of the controller120, the display unit115may display the cursor as a dark or light color or the size of the cursor as large or small.

The touch sensor117may be mounted on the display unit115. The display unit115may sense the touch generated by the access by the object or contact and canceled contact by the object. The touch sensor117determines a coordinate of the area in which the access by the object or contact and canceled contact by the object is sensed, and transmits the detected coordinate to the controller120. Here, the touch sensor117may sense the capacitance which changes according to the access by the object or contact and canceled contact by the object sensed on the touch screen110.

The touch screen110using the touch sensor117may recognize the area in which the touch is sensed through the change of the capacitance which is generated when the object having conductivity, such as the finger of the user, contacts the touch screen110coated with a conductive material. As a result, the value of the capacitance increases as the object having conductivity approaches the touch screen110and as the area contacted on the touch screen110has widened.

Referring toFIGS. 2A and 2B, if an object, such as the finger of the user, approaches the touch screen110, the capacitance gradually begins to increase as illustrated in the graph inFIG. 2A. If the object contacts the touch screen110, the capacitance has a maximum value as illustrated in the graph inFIG. 2B. The touch sensor117mounted on the capacitive overlay type touch screen110may transmit information corresponding to the capacitance, which changes according to the access by the object or contact and canceled contact by the object, to the controller120to confirm the area in which the access by the object or contact and canceled contact by the object is sensed.

The controller120controls the state and the operation of the overall configurations of the portable terminal. More particularly, the controller120determines whether the information corresponding to the capacitance received from the touch screen110is included in a critical value stored in the storage unit130, and may confirm the area in which the access by the object or contact and canceled contact by the object is sensed.

A peak compare method and a frequency conversion method may be used for the controller120to determine an area in which the access by the object or contact and canceled contact by the object is sensed according to the change of capacitance. In the peak compare method, the peak, which is a maximum demand voltage, reduces when the capacitance increases due to the contact by the object having conductivity, such as the finger of the user or a stylus, on the touch screen110. In the frequency conversion method, the frequency is decreased when the capacitance increases due to the contact by the object having conductivity on the touch screen110.

In other words, the controller120confirms the peak or the frequency which changes according to the capacitance, and may sense the access by the object or contact and canceled contact by the object on the touch screen110. Moreover, the controller120may determine the area in which the access by the object or contact and canceled contact by the object is sensed through the peak or the frequency which changes according to the capacitance. In an exemplary implementation, by using the change of the capacitance, the controller120may display the cursor in the area in which the access by the object or contact and canceled contact by the object is sensed.

More specifically, the controller120may display the cursor in the area in which the capacitance is confirmed by comparing the confirmed capacitance and the critical value stored in the storage unit130. At this time, the critical value stored in the storage130may be classified into a plurality of critical values, for example, a first critical value and a second critical value. The first critical value is a reference value which displays the cursor in the area where the access by the object is sensed on the touch screen110, and the second critical value is a reference value which confirms the contact by the object with the touch screen110.

Thus, the controller120may display the cursor in the area in which the capacitance is confirmed. That is, the controller120may display the cursor in the area accessed in which the object is sensed on the touch screen110when the confirmed capacitance is equal to or greater than the first critical value, and is less than the second critical value. The controller120confirms the capacitance in the area in which the cursor is displayed and determines whether the confirmed capacitance is equal to or greater than the second critical value. If the capacitance is equal to or greater than the second critical value, the controller120may perform a function mapped in the area in which the cursor is displayed. At this time, the first critical value and the second critical value may be set by a manufacturer of the portable terminal or may be set by the user.

In an exemplary implementation, the first critical value and the second critical value, as described in an exemplary embodiment of the present invention, are set by the user. If the user selects a setup mode through a menu or a function key to set the first critical value and the second critical value, the controller120displays a screen which indicates a cursor setup mode on the touch screen110. At this time, the controller120displays a first sensing window which may set the first critical value and a second sensing window which may set the second critical value.

The controller120confirms the capacitance which changed according to the access by the object to the first sensing window, and displays the cursor in the area in which the change of the capacitance is sensed. The controller120confirms the capacitance which changes according to the access of by the object. Here, if the access by the object is sensed in the first sensing window, the controller120displays the cursor in the area in which the access by the object is sensed in the first sensing window. The controller120may display a message, such as ‘move finger or stylus near touch screen110’ on the display unit115with a pop up message or an overlay type message. Accordingly, the user may recognize that an object, such as the finger or the stylus, should not have contact with the first sensing window displayed on the touch screen110.

The controller120then confirms whether the contact by the object is sensed in the second sensing window and confirms the capacitance changed according to the contact by the confirmed object. In this case, the controller120may display a message, such as ‘contact finger or stylus to touch screen110’ on the display unit115with the pop up message or the overlay type message. Based on the message displayed, the user may recognize that the object has to have contact with the second sensing window displayed on the touch screen110.

If the capacitance is confirmed, the controller120determines whether the storing of a value corresponding to the capacitance is selected through the touch screen110. If the storing of the capacitance value is selected, the controller120may store the capacitance value confirmed in the first sensing window and the second sensing window in the storage unit130with the first critical value and the second critical value. Here, a method implemented by the controller120determines whether an object has contact with the touch screen110is described below.

An assumption is made herein that a maximum capacitance which may be confirmed in the capacitive overlay type touch screen110is preset in the storage unit130. The controller120confirms the capacitance which is generated when the object has contact with the touch screen110. The controller120determines whether the confirmed capacitance has a value which is close to the preset capacitance. If the confirmed capacitance has a value which is close to the preset capacitance, the controller120may determine that the object has contact with the touch screen110. The storage unit130stores various applications which are necessary when the portable terminal performs functions and various data which is generated while functions are performed in the portable terminal. More particularly, the storage unit130stores the first critical value and the second critical value which is set to sense the contact by the object in the capacitive overlay type touch screen110. Here, the first critical value is a reference value for displaying the cursor in the area in which the access by the object is sensed, and the second critical value is a reference value for confirming the contact by the object in the touch screen110.

Although not illustrated in the drawings, the portable terminal may further include various configurations according to the functions which may be performed in the portable terminal, such as a communications unit which performs a communication function between the portable terminal and a base station, a camera unit which takes a picture of images, a Digital Multimedia Broadcasting (DMB) receiver which receives a digital broadcasting signal, an internet receiver which performs an internet function by communicating with an internet network, and the like. In an exemplary implementation, if the access by the object is sensed through the touch screen110of the portable terminal, the controller120determines whether the capacitance changing according to the access by the object is equal to or greater than the first critical value, and is less than the second critical value.

If the changed capacitance is equal to or greater than the first critical value, and is less than the second critical value, the controller120displays the cursor in the area in which the access by the object is sensed by controlling the touch screen110. Moreover, if the contact by the object is sensed, the controller120determines whether the capacitance which changes according to the contact by the object is equal to or greater than the second critical value. If the changed capacitance is equal to or greater than the second critical value, the controller120confirms the function mapped in the area in which the contact by the object is sensed and may perform the confirmed function. The method implemented by the controller120for displaying the cursor according to the access by the object, contact and canceled contact by the object is illustrated with reference toFIG. 3.

FIG. 3is a flowchart illustrating a method for displaying a cursor according to an exemplary embodiment of the present invention.FIG. 4is an exemplary view of a screen displaying a cursor on a touch screen according to an exemplary embodiment of the present invention.

Referring toFIG. 3, the controller120displays a screen corresponding to a mode performed in the portable terminal on the touch screen110in step310. Here, the mode operated in the portable terminal denotes all modes that may be operated in the portable terminal, such as a standby mode, a game mode, a short message writing mode, and the like. The controller120then determines whether a change of capacitance is sensed through the touch screen110in step315.

For example, the controller120determines whether access by an object of a user for selecting a given area on the touch screen110is sensed. If the object approaches the touch screen110, the controller120senses the capacitance which changes according to the access by the object through the touch screen110. The controller120then confirms the changed capacitance and the area in which the change of the capacitance is sensed in the touch screen110in step320. The controller120compares the confirmed capacitance with a first critical value stored in the storage unit130, and determines whether the confirmed capacitance is equal to or greater than the first critical value in step325.

At this time, the controller120may confirm whether the confirmed capacitance is equal to or greater than the first critical value, as well as whether the confirmed capacity is less than a second critical value. If the confirmed capacitance is equal to or greater than the second critical value, the controller120may determine the contact by the object, since the second critical value is set to sense the contact by the object.

Accordingly, the controller120may determine that the confirmed capacitance is equal to or greater than the first critical value and less than the second critical value. If the confirmed capacitance is less than the set first critical value, the controller120returns to step315and determines whether the change of the capacitance is sensed. If the confirmed capacity is equal to or greater than the set first critical value, the controller120, as illustrated inFIG. 4, displays the cursor in the area in which the capacitance is sensed in step330.

More specifically, an assumption is made herein that the first critical value is stored with 5 μF, and the second critical value is stored with 9 μF. If the object approaches the touch screen110, the controller120confirms the change of the capacitance through the touch screen110. If the changed capacitance is 6 μF, the confirmed capacitance is 5 μF or greater than 5 μF, which is the set first critical value, and less than 8 μF, which is the second critical value, so that the controller120, as illustrated inFIG. 4, may display the cursor in the area in which the change of the capacitance is sensed. For example, an assumption is made herein that the touch screen110, as illustrated inFIG. 4, displays a website in an internet mode under the control of the controller120. If the user moves the object, such as the finger of the user or the stylus, close to the touch screen110to select contents in the website which are displayed, the controller120senses the change of capacitance due to the access by the object and confirms the area in which the capacitance is sensed.

The controller120confirms the changed capacitance, and determines whether the confirmed capacitance is equal to or greater than the first critical value, and is less than the second critical value. If the confirmed capacitance is equal to or greater than the first critical value, and is less than the second critical value, the controller120may display a block type cursor in the area in which the change of the capacitance is sensed. In other words, as illustrated inFIG. 4, in the touch screen110, the block type cursor may be displayed in the area to which the finger of the user is approaching.

In an exemplary implementation, the controller120displays the block type cursor in the area in which the change of the capacitance is sensed. However, the present invention is not limited thereto. The area in which the change of the capacitance is sensed may be displayed with a highlight. The controller120may enlarge and display the content (for example, a character, an image, an icon, and the like) displayed in the area in which the change of the capacitance is sensed. Accordingly, when the object, such as the finger of the user, approaches the touch screen110and the object moves, the controller120may enlarge and display the content displayed in the area in which the change of the capacitance is sensed according to the movement of the object.

Moreover, the controller120displays a colored cursor displayed in the area in which the change of the capacitance is sensed according to a variation of the capacitance to be darker or lighter than the original color of the contents displayed on the touch screen110. For example, if the capacitance sensed through the touch screen110is 1 μF, the controller120displays the color of the cursor displayed in the area in which the change of the capacitance is sensed. If the sensed capacitance is increased, the controller120may display the color of the cursor displayed in the area in which the change of the capacitance is sensed. Then, if the sensed capacitance is decreased, the controller120may display the color of the cursor displayed in the area in which the change of the capacitance is sensed to be light according to the reduced capacitance.

Otherwise, the controller120may enlarge or reduce to display together the cursor displayed in the area in which the change of the capacitance is sensed according to the variation of the capacitance and the content displayed in the area in which the change of the capacitance is sensed. For example, if the sensed capacitance is 1 μF, the controller120may display the cursor and content displayed in the area in which the change of the capacitance is sensed, with the originally displayed size. Also, if the sensed capacitance is increased, the controller120may display the cursor and content displayed in the area in which the change of the capacitance is sensed to be greater than the originally displayed size according to the increased capacitance. Then, if the sensed capacitance is decreased, the controller120may display the cursor and content displayed in the area in which the change of the capacitance is sensed with the originally displayed size according to the decreased capacitance.

Accordingly, by displaying the color and size of the cursor differently according to the variation of the capacitance, the user may recognize the distance from which the object, such as, the finger of the user or the stylus, approaches the touch screen110. The controller120displaying the cursor in the area in which the changed capacitance is sensed according to the access by the object determines whether the capacitance sensed in the area in which the cursor is displayed is equal to or greater than the second critical value in step335.

In other words, if the object, such as the finger of the user or the stylus, has contact with the touch screen110to select the area in which the cursor is displayed, the controller120confirms the capacitance changed from the contact by the object through the touch screen110. The controller120compares the confirmed capacitance with the second critical value stored in the storage unit130and determines whether the confirmed capacitance is equal to or greater than the second critical value. For example, if the second critical value is set to 15 μF, the controller120determines whether the value of the capacitance sensed in the area in which the cursor is displayed through the touch screen110is 15 μF or greater than 15 μF. If the capacitance is equal to or greater than the second critical value, the controller120confirms the function corresponding to the area in which the cursor is displayed in step340.

If the capacitance is confirmed to be equal to or greater than the second critical value, the object, such as the finger of the user or the stylus, has contact with a select area of the touch screen110. Accordingly, if the capacitance is equal to or greater than the second critical value, the controller120confirms the function mapped in the area in which the change of the capacitance is sensed. That is, the controller120confirms the function mapped in the area in which the cursor is displayed. On the other hand, if the capacitance is not equal to or greater than the second critical value, the controller120performs step315again. The controller120confirming the function corresponding to the area in which the cursor is displayed determines whether the contact is canceled in step345.

In the method for determining whether the contact is canceled, the controller120compares the capacitance with the first critical value and may determine that the contact is canceled when the capacitance is less than the first critical value. Moreover, the controller120may determine that the object that has contact with the touch screen110is released as the capacitance draws near 0μF. If the contact is not canceled, the controller120returns to step335. However, if the contact is canceled, the controller120performs the function corresponding to the area in which the cursor is displayed in step350.

Here, the function which may be performed includes all the functions which may be performed in all modes of the portable terminal. For example, if the mode of the portable terminal includes a menu selection mode, the selected menu may be displayed. If the mode of the portable terminal is a Moving Picture Expert Group Layer-3 (MP3) play mode, a selected MP3 file may be played. Also, if the mode of the portable terminal is a short message writing mode, the controller120may display a character corresponding to the area in which the cursor is displayed on the touch screen110. Further, if the mode of the portable terminal is an internet mode, the controller120connects to the website corresponding to the content corresponding to the area in which the cursor is displayed and may display the connected website on the touch screen110.

In an exemplary implementation, if the access by the object, such as the finger of the user, is sensed in the touch screen110which is included in the portable terminal, the controller120confirms the capacitance which changes according to the access by the object, and may display the cursor in the area in which the change of the capacitance is sensed according to the confirmed capacitance. Based on the cursor which is displayed, the user may confirm the area touched on the touch screen110.