WO2008054185A1

WO2008054185A1 - Method of moving/enlarging/reducing a virtual screen by movement of display device and hand helded information equipment using the same

Info

Publication number: WO2008054185A1
Application number: PCT/KR2007/005555
Authority: WO
Inventors: Hee Han
Original assignee: Hee Han
Priority date: 2006-11-03
Filing date: 2007-11-05
Publication date: 2008-05-08
Also published as: KR20070004466A; KR100963679B1; KR20080040614A

Abstract

Provided is a method of moving on a virtual screen displayed on a display device of a portable information terminal and enlarging/reducing the virtual screen by detecting movement of the display device unlike a conventional method of moving a virtual screen using an input unit such as a mouse or a keyboard. Thus, a high-resolution virtual screen can be easily used and limitations of a small display device of a portable information terminal can be removed. A desired region of the virtual screen can be seen, and the virtual screen can be enlarged or reduced by moving the display device above the virtual screen like the case of moving a magnifier above a newspaper, therefore a user can easily and conveniently use the virtual screen. Furthermore, movement of the display device can be accurately detected using a gyro sensor or a camera.

Description

METHOD OF MOVING/ENLARGING/REDUCING A VIRTUAL

SCREEN BY MOVEMENT OF DISPLAY DEVICE AND HAND

HELDED INFORMATION EQUIPMENT USING THE SAME

Technical Field

[1] The present invention relates to technology for a portable information terminal, and more particularly, to a method of moving on a virtual screen, enlarging/reducing the virtual screen, and moving a virtual cursor by moving a display device of a portable information terminal, and a portable information terminal using the method. Background Art

[2] The use of portable information terminals has been increased over the years.

Furthermore, with the development of wired/wireless communications, multimedia service markets have been rapidly expanded for providing a variety of multimedia data services through portable information terminals.

[3] However, current portable information terminals have a small display device for portability, thereby limiting the expansion of the multimedia service markets. That is, since a large display device increases the weight and size of portable information terminals although it is advantageous for displaying information, current portable information terminals use a small display device for portability.

[4] Since it is difficult to reduce the size of pixels of small display devices, small display devices have poor resolution. This is one of the major factors reducing the legibility. For example, cellular phones provide web images or other information after converting the resolution of such contents in accordance with the wireless application protocol (WAP) due to poor display environments thereof.

[5] For these reasons, many efforts have been made to reduce the size of pixels of small display devices. However, under the current technology, it is very difficult or expensive to reduce the size of pixels of small display devices. For example, a small, high-resolution display device for a portable information terminal, such as a 1024x768 display device, is expensive and not enough to provide good legibility for tiny objects or characters of an image.

[6] In an attempt to overcome the limitations of a small display device, an enlarged virtual screen having high resolution is made using software. The enlarged virtual screen can be moved to the real screen of the small display device using a keyboard or mouse. This technology had been applied to some laptop computers. This technology is advantageous in that an enlarged virtual screen can be displayed on a small screen of a display device by manipulating a keyboard or a mouse. However, the manipulation of the keyboard or mouse is difficult, and the movement of the virtual screen is not smooth.

Disclosure of Invention

Technical Problem

[7] In the related art, a high-resolution virtual screen created using software for overcoming limitations of a small display screen is moved relative to the fixed display screen by using a mouse or a keyboard. Current portable information terminal are much smaller and lighter than conventional laptop computers or notebook computers and thus they are more easily carried. The present invention uses this fact for manipulating a virtual screen.

[8] Accordingly, the present invention is provides a method of moving on a virtual screen and enlarging/reducing the virtual screen by moving a display device of an information terminal relative to the fixed virtual screen like the case of seeing a newspaper using a magnifier, and a portable information terminal using the method. Technical Solution

[9] In one embodiment, there is provided a method of moving on a virtual screen and enlarging/reducing the virtual screen by moving a display device of a portable information terminal so as to display a desired region of the virtual screen on the display device, the virtual screen having an increased resolution and configured to be displayed on the display device for improving legibility of an image displayed on the display device, the method being characterized in that the method includes: setting a reference position of the display device; enlarging or reducing the virtual screen displayed on the display device using detected information about forward or backward movement of the display device relative to the reference position; and moving upward, downward, leftward, or rightward on the virtual screen using detected information about vertical or horizontal movement of the display device relative to the reference position.

[10] In another embodiment, when the display device of the portable information terminal is moved forward relative to the reference position, the virtual screen displayed on the display device is enlarged, and when the display device is moved backward relative to the reference position, the virtual screen displayed on the display device is reduced. When the display device is moved leftward relative to the reference position, a left region of the virtual screen is displayed on the display device. When the display device is moved rightward relative to the reference position, a right region of the virtual screen is displayed on the display device. When the display device is moved upward relative to the reference position, an upper region of the virtual screen is displayed on the display device. When the display device is moved downward relative to the reference position, a lower region of the virtual screen is displayed on the display device.

[11] In a further embodiment, there is provided a portable information terminal for displaying a desired region of a virtual screen on a display device and enlarging/ reducing the virtual screen according to movement of the display device, the portable information terminal including: a memory configured to store contents to be displayed; a display device configured to display the contents stored in the memory according to a control signal; a position detector configured to detect position information; an input unit; and a controller, wherein when a set command is input through the input unit, the controller sets a current position of the display device detected by the position detector to a reference position; when movement of the display device is detected, the controller compares the reference position with a position of the display device detected by the position detector so as to calculate displacements of the display device in upward, downward, leftward, rightward, forward, and backward directions; when the display device is moved forward or backward, the controller enlarges or reduces the virtual screen displayed on the display device according to the calculated displacement in the forward or backward direction; and when the display device is moved upward, downward, leftward, or rightward, the controller controls the display device to display an upper, lower, left, or right region of the virtual screen according to the calculated displacement in the upward, downward, leftward, or rightward direction. The position detector may be a gyro sensor or a camera.

[12] In a still further embodiment, there is provided a method of manipulating a virtual mouse by moving a display device of a portable information terminal, the method including: fixing a mouse cursor to a predetermined position of the display device; moving the mouse cursor relative to a virtual screen by moving the display device upward, downward, leftward, or rightward; when the virtual cursor is placed on a click bar of the virtual screen, displaying the state of the virtual cursor placed on the click bar; and clicking the click bar using the virtual cursor by clicking an input unit of the portable information terminal.

Advantageous Effects

[13] In the related art, a desired region of a virtual screen can be displayed on a display device by moving the virtual screen relative to the display device using a mouse or a keyboard. However, according to the present invention, a desired region of the virtual screen can be seen by moving the display device so that a user can feel that he/she sees a desired region of a virtual screen by moving a window to the region.

[14] Furthermore, according to the present invention, a high-resolution virtual screen is used to overcome limitations of a small display device of a portable information terminal so that much data or more menus can be provided for a user using a much wider virtual screen. Therefore, according to the present invention, even a cellular phone can provide a wide screen for a user without having to increase the size of a display device of the cellular phone. Furthermore, according to the present invention, a desired region of an enlarged virtual screen can be displayed on a display device by moving the display device upward, downward, leftward, or rightward like the case of moving a magnifier above a spread newspaper. A user can easily enlarge or reduce the virtual screen by moving the display device forward or backward, like the case where a person moves forward to see details of an object and backward to see the object broadly. Furthermore, since the virtual screen can be used by natural movement of a user without having to manipulate a keyboard or buttons, users can conveniently use the virtual screen. Furthermore, when the present invention is applied to an information terminal having a camera, movement of the information terminal can be detected using the existing camera without an additional device, thereby reducing manufacturing costs. Furthermore, according to the present invention, a virtual cursor or keypad can be used to manipulate the virtual screen instead of a mouse or a keypad so that a small and light information terminal can be provided. Brief Description of the Drawings

[15] FIG. 1 is a schematic view illustrating a method of displaying another region of a virtual screen on a screen of a portable information terminal by moving the portable information terminal according to an embodiment of the present invention.

[16] FIG. 2 is a schematic view for explaining enlargement/reduction of a virtual screen upon forward/backward movement of a display device when image data having a resolution higher than that of the display device are stored in a memory according to an embodiment of the present invention.

[17] FIG. 3 is a flowchart illustrating procedures for initially setting display conditions, calculating screen magnification ratios and displaying a virtual screen upon movement of a display device according to an embodiment of the present invention.

[18] FIG. 4 is a block diagram of an information terminal providing a virtual screen using position information detected by a gyro sensor according to an embodiment of the present invention.

[19] FIG. 5 is a block diagram of an information terminal providing a virtual screen using position information detected by a camera according to another embodiment.

[20] FIG. 6 is a schematic view for explaining a method of detecting movement by comparing a reference region with a comparison image according to an embodiment of the present invention.

[21] FIG. 7 is a schematic view for explaining a method of detecting forward/backward movement by comparing a reference region with a comparison image according to an embodiment of the present invention.

[22] FIG. 8 is a schematic view illustrating a virtual cursor created using software at a fixed position of a display device and movement of the virtual cursor relative to a virtual screen according to an embodiment of the present invention. Best Mode for Carrying Out the Invention

[23] Reference will now be made in detail to the embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. The present disclosure may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein.

[24] 1. Method of displaying virtual screen using movement information of portable information terminal.

[25] FIG. 1 is a schematic view illustrating a method of displaying another region of a virtual screen on a screen of a portable information terminal by moving the portable information terminal according to an embodiment of the present invention.

[26] Referring to FIG. 1, when a user 40 moves an information terminal 10 vertically or horizontally, an upper, lower, left, or right region of a virtual screen 30 can be displayed on a display device 20 of the information terminal 10. Furthermore, when the user 40 moves the information terminal 10 forwardly away from himself/herself, the virtual screen 30 can be displayed on the display device 20 on a large scale. In addition, when the user 40 moves the information terminal 10 backwardly to himself/ herself, the virtual screen 30 can be displayed on the display device 20 on a small scale.

[27] In FIG. 1, the information terminal 10 has a position detection function, and reference numeral 20 denotes the display device of the information terminal 10. Reference numeral 30 denotes the virtual screen.

[28] In a conventional portable information terminal, a display window of a display device has substantially the same meaning as a screen. For example, a cellular phone having a 240x320 pixel QVGA graphic display device may have a 240x320 screen size. However, according to the present invention, a large virtual screen such as the virtual screen 30 (e.g., a 1024x768 pixel screen) is stored in a memory using a graphic driver, and a 240x320 region of the virtual screen 30 is displayed on the display device 20 according to movement of the information terminal 10.

[29] According to the present invention, it would seem that the virtual screen 30 is located at a place along which the display device 20 moves. Therefore, the user 40 can use the display device 20 of the information terminal 10 as a magnifier by moving the display device 20 relatively to the virtual screen 30 formed at a front side of the user 40 so that the virtual screen 30 having a resolution larger than that of the display device 20 can be provided to the user 40 without having to physically increase the size or resolution of the display device 20. Here, the size of the virtual screen 30 can be determined based on the distance between the user 40 and the display device 20 positioned at a front side of the user 40.

[30] FIG. 2 is a schematic view for explaining enlargement/reduction of a virtual screen upon forward/backward movement of a display device when image data having a resolution higher than that of the display device are stored in a memory according to an embodiment of the present invention.

[31] Referring to FIG. 2, reference numeral 1 denotes resolution Rd of the display device, reference numeral 2 denotes resolution Rv of the virtual screen, and reference numeral 3 denotes resolution Rc of contents stored in the memory. Reference numeral 4 denotes an enlarged virtual screen region where the contents stored in the memory can be showed on an enlarged scale, and reference numeral 5 denotes a reduced virtual screen region wherein the contents can be showed on a reduced scale.

[32] When the size of the virtual screen 30 is smaller than the resolution Rc of the contents stored in the memory (that is, when the virtual screen 30 is located in the reduced virtual screen region 5 close to a user), the contents can be displayed on the limited display device 20 on a reduced scale based on movement of the display device 20. When the size (resolution Rv) of the virtual screen 30 is larger than the resolution Rc of the contents (i.e., when the virtual screen 30 is located in the enlarged virtual screen region 4), the contents can be displayed on the display device 20 on an enlarged scale based on movement of the display device 20.

[33] As shown in FIG. 2, when the resolution of the contents stored in the memory is

Rc(3), the resolution of the display device 20 is Rd(I), the resolution of the virtual screen 30 selected by moving the display device 20 backward or forward is Rv (2), and the display device 20 is located at an initial position dl, the Rc(3)-resolution contents is displayed on the entire area of the Rd(l)-resolution display device 20 on a reduced scale. In this case, the reduction ratio is Rc/Rd = kL, where k denotes an adjustable proportional constant, and L denotes a distance between the initial position dl of the display device 20 and a position d2 corresponding to the resolution Rc(3) of the contents stored in the memory. For example, when k = 2, the resolution Rc of the contents is ten times the resolution Rd of the display device 20, the reduction ratio is 10, and the L can be 5 cm. When d < L (d denotes a distance between the initial position dl of the display device 20 and a position corresponding to the resolution Rv of the virtual screen), the resolution Rv of the virtual screen 30 is Rv = Rc/k(L-d), and when d > L, Rv = Rc(d-L)*k. Here, only a portion of the virtual screen 30 corresponding to Rd/Rv is displayed on the display device 20. However, the other portions of the virtual screen 30 can be displayed on the display device 20 by moving the display device 20 vertically or horizontally. If the resolution Rv of the contents is equal to the resolution Rd of the display device 20, the initial position of the display device 20 is the position d2. In this case, forward movement of the display device 20 results in operation of the display device 20 in the enlarged virtual screen region 4.

[34] When the above-described method of using a virtual screen is applied to an information terminal, it may be unnecessary to increase the size of the virtual screen to an unlimited extent. That is, an upper limit of the size of the virtual screen can be set. Furthermore, when the display device 20 is moved vertically or horizontally, it may be unnecessary to display an outer region of the virtual screen 30. Thus, when the display device 20 reaches an edge of the virtual screen 30 while moving over the virtual screen 30, although the display device 20 is further moved to an outer region of the virtual screen 30, relative movement between the display device 20 and the virtual screen 30 may be disabled to inform a user that the display device 20 has reached edge of the virtual screen 30. For example, when the display device 20 is moved out of a region ABCD (refer to FIG. 2), relative movement between the display device 20 and the virtual screen 30 may be disabled.

[35] FIG. 3 is a flowchart illustrating procedures for initially setting display conditions, calculating screen magnification ratios and displaying a virtual screen upon movement of a display device according to an embodiment of the present invention.

[36] Referring to FIG. 3, in operation Sl, a user initially sets a reference position, an operation length L, and a maximal magnification ratio. The virtual screen can be displayed only when the user selects a virtual screen mode using a button switch or keyboard so as to reduce calculation works of an information terminal.

[37] When the user selects the virtual screen mode, a location detection module detects the location of the display device and transmits detected results to a processor in operation S2. Then, in operation S3, the processor calculates a screen magnification ratio based on the distance between the user and the display device, and a location of the display device relative to the virtual screen based on movement of the display device on a plane parallel to the virtual screen.

[38] Thereafter, in operations S4 and S5, a display controller transmits a necessary portion of contents stored in a memory to the display device for displaying the contents on an enlarged or reduced scale according to calculation results received from the processor.

[39] When a user moves an information terminal forwardly away from himself/herself, a portion of an enlarged virtual screen can be displayed on a display device of the information terminal according to the above-described procedures, thereby providing an enlarged screen to the user of the information terminal. When the user moves the in- formation terminal toward himself/herself, a portion of the virtual screen can be displayed on the display device of the information terminal on a less enlarged scale, thereby providing scale-down effects for the user. In other words, the virtual screen spreads out in front of a user like a newspaper, and the user can move the display device above the virtual screen like a magnifier to see a desired region of the virtual screen on a desired scale. Therefore, according to the present invention, problems concerned with legibility caused by a small display device of an information terminal can be removed.

[40] 2. Method of detecting movement of display device from portable information terminal.

[41] A. Use of gyro sensor for three-dimensional position detection.

[42] FIG. 4 is a block diagram of an information terminal 10 providing a virtual screen using position information detected by a gyro sensor 11 according to a first embodiment of the present invention. The gyro sensor 11 is attached to the information terminal 10, and the information terminal 10 provides a virtual screen using position information detected by the gyro sensor 11.

[43] Referring to FIG. 4, the information terminal 10 of the current embodiment the gyro sensor 11 for detecting position information, a processor 12, a memory 13 for storing display data, a display controller 14, an input unit 18, and a display 20.

[44] Information detected by the gyro sensor 11 is transmitted to the processor 12, and then the processor 12 calculates the position of the display 20 using the received information. The calculation results of the processor 12 are transmitted to the display controller 14 so that a portion of high-resolution display data stored in the memory 13 can be displayed on the display 20. In the current embodiment, although the price, volume, and weight of the information terminal 10 can increase due to the gyro sensor 11, the information terminal 10 can provide a virtual screen based on accurate position information.

[45] B. Use of camera attached to portable information terminal

[46] FIG. 5 is a block diagram of an information terminal providing a virtual screen using position information detected by a camera 17 according to a second embodiment of the present invention. In the current embodiment, the information terminal uses position information detected by the camera 17 that is not used in normal mode.

[47] The information terminal of the current embodiment includes the camera 17, a controller 16, a dedicated signal processor 15, a processor 12, a memory 13, a display controller 14, an input unit 18, and a display 20.

[48] Referring to FIG. 5, information detected by the camera 17 is processed by the dedicated signal processor 15 and is stored in the memory 13. In the current embodiment, when the processor 12 receives a position detection command through the input unit 18 such as a button, the processor 12 operates the dedicated signal processor 15 or a software module to detect the position of the display 20 as follows.

[49] 1) Detecting movement on two-dimensional plane in up, down, left, and right directions.

[50] Images detected by the camera 17 are selected at regular time intervals or on a frame basis, and then the selected images are compared to detect movement of the display 20. In an embodiment shown in FIG. 6, a reference image window 22 having MxN pixels (Lg., 5x5 pixels) is extracted from a center portion of a reference image 21. Then, while moving the reference image window 22 on a comparison image 23, differences between the reference image window 22 and regions of the comparison image 23 are calculated. Thereafter, a region of the comparison image 23 corresponding to the minimum of the calculated differences is compared with the center of the reference image 21 to calculate the amount and direction of movement of the display 20. Reference numeral 24 denotes an arrow indicating the amount and direction of movement of the display 20. This method corresponds to two-dimensional correlation image processing technology. That is, when the comparison image 23 is denoted by Y(i,j) and the reference image 21 is denoted by X(n,m), the result of a two- dimensional correlation calculation can be W(i,j) as shown in Equation 1 below.

[51] [Equation 1]

[52]

[53] where [] indicate an absolute value, n and m denote the numbers of rows and columns of pixels of the reference image 21, respectively. L calculations are performed by n and m times, respectively. This calculation can be performed on sequential image frames to obtain sequential position information.

[54] 2) Detecting forward and backward movement of display device

[55] FIG. 7 is a schematic view for explaining a method of detecting forward/backward movement by comparing a reference region with a comparison image according to an embodiment of the present invention.

[56] A reference image window 22 having MxN pixels is extracted from a center portion of a reference image 21. Then, while moving the reference image window 22 on a comparison image 23, differences between the reference image window 22 and regions of the comparison image 23 are calculated.

[57] Images captured by the camera 17 while moving the information terminal 10 forward or backward are sequentially enlarged or reduced images. Thus, the comparison image 23 is compared with the reference image window 22 while gradually enlarging or reducing the comparison image 23 to find out a magnification ratio of the comparison image 23 at which the different between the comparison image 23 and the reference image window 22 is minimal. Information about forward/ backward movement of a display device can be obtained from the magnification ratio.

[58] More accurate information can be obtained by increasing the size of the reference image window 22 or enlarging/reducing the comparison image 23 in much more steps. However, this adjustment increases calculation time. Therefore, the adjustment can be carried out in a manner such that the increased calculation time is less than a time interval between images captured by the camera 17.

[59] 3. Creating virtual mouse and keyboard using movement information of display device.

[60] A. Use of virtual cursor

[61] The size of Information terminals reduces to, for example, the size of mice.

Therefore, the sizes of peripheral devices largely affect the design of an information terminal. To obviate these problems, a virtual mount and a virtual keyboard are provided according to an embodiment of the present invention.

[62] Referring to FIG. 8, a mouse cursor 50 (hereinafter, referred to as a virtual cursor) is fixedly overlapped on a predetermined position (i.g., a center position) of a display device of an information terminal 10 in a software manner. It can be programmed such that the virtual cursor 50 presents on the display device only when the display device moves so as to prevent the virtual cursor 50 from screening an image displayed on the display device. Next, the virtual cursor 50 can be located at a predetermined position such as a linked position of a virtual screen 52 by moving the information terminal 10. Then, the predetermined position can be clicked using the virtual cursor 50 by pressing a predetermined button of the information terminal 10.

[63] As explained above, the virtual cursor 50 is used in a manner opposite to a conventional method in which a mouse curse is moved on a fixed screen of a fixed display device. That is, in the current embodiment, a virtual cursor is fixed to a predetermined position of a display device, and then the display device is moved to see a desired region of a virtual screen and place the virtual cursor on a click point of the virtual cursor. Furthermore, the same concept can be applied to a keyboard or keypad for realizing a virtual keyboard. For example, after creating a virtual keypad on a virtual screen of a cellular phone or personal digital assistant (PDA), a virtual cursor can be placed on a desired key of the virtual keypad by moving the cellular phone or PDA upward, downward, leftward, or rightward. Then the desired key can be clicked using the virtual cursor.

[64] B. Use of camera attached to portable information terminal

[65] When a virtual cursor is fixed to a predetermined position of a display device, a linked point located in a boundary region of a virtual screen cannot be clicked using the virtual cursor. Thus, an outer margin region adjoining the virtual screen can also be displayed in order to allow a linked point located in a boundary region of the virtual screen to be clicked using the virtual cursor. However, in this case, an additional storage space of a memory may be required to store information about the outer margin region, and it may be unnatural to display the virtual screen together with the outer margin region.

[66] It is necessary to reduce the size of the outer margin region. For this, a user can move the display device forward away from himself/herself to display a boundary region of the virtual screen on an enlarged scale. This practically reduces the distance between the boundary of the virtual screen and the virtual cursor. For example, the virtual cursor can be placed on a linked point located at a boundary region of the virtual screen by adding a margin region about 1/4 times as wide as that of the display device to the virtual screen when the magnification ratio of the virtual screen is 4.

[67] According to the above-described method, interface devices such as a mouse and a keyboard can be replaced with virtual devices. Therefore, inexpensive, small, and light information terminals can be realized.

[68] C. Clicking by moving virtual cursor using information about movement of display device.

[69] Instead of using an outer margin region, the virtual cursor can be moved on the display device according to movement of the display device when the display device re aches a boundary of a virtual screen. In this case, it is unnecessary to add an outer margin region to a virtual screen to place the virtual cursor on a boundary region of the virtual screen. That is, when the display device reach a boundary region of a virtual screen, relative movement between the display device and the virtual screen is disabled, and then the virtual cursor is moved according to movement of the display device so as to place the virtual cursor on a liked point located in the boundary region of the virtual screen. Here, the speed of the virtual cursor on the display device can be set to a proper value according to movement of the display device for convenience use of the virtual cursor.

[70] While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.

Claims

[1] A method of moving on a virtual screen and enlarging/reducing the virtual screen by moving a display device of a portable information terminal so as to display a desired region of the virtual screen on the display device, the virtual screen having an increased resolution and configured to be displayed on the display device for improving legibility of an image displayed on the display device, the method being characterized in that the method comprises: setting a reference position of the display device; enlarging or reducing the virtual screen displayed on the display device using detected information about forward or backward movement of the display device relative to the reference position; and moving upward, downward, leftward, or rightward on the virtual screen according to detected information about vertical or horizontal movement of the display device relative to the reference position.

[2] The method of claim 1, wherein when the display device of the portable information terminal is moved forward relative to the reference position, the virtual screen displayed on the display device is enlarged, and when the display device is moved backward relative to the reference position, the virtual screen displayed on the display device is reduced.

[3] The method of claim 1, wherein when the display device is moved leftward relative to the reference position, a left region of the virtual screen is displayed on the display device; when the display device is moved rightward relative to the reference position, a right region of the virtual screen is displayed on the display device; when the display device is moved upward relative to the reference position, an upper region of the virtual screen is displayed on the display device; and when the display device is moved downward relative to the reference position, a lower region of the virtual screen is displayed on the display device.

[4] The method of claim 2 or 3, wherein the enlarging or reducing of the virtual screen, or the moving upward, downward, leftward, or rightward on the virtual screen comprises disabling the enlarging or reducing of the virtual screen or the moving on the virtual screen to inform a user that the display device reaches a boundary region of the virtual screen when the display device is moved out of a preset region, wherein movement of the display device in the preset region is previously correlated with the resolution of the virtual screen.

[5] A portable information terminal for displaying a desired region of a virtual screen on a display device and enlarging/reducing the virtual screen according to movement of the display device, the portable information terminal comprising: a memory configured to store contents to be displayed; a display device configured to display the contents stored in the memory according to a control signal; a position detector configured to detect position information; an input unit; and a controller, wherein when a set command is input through the input unit, the controller sets a current position of the display device detected by the position detector to a reference position; when movement of the display device is detected, the controller compares the reference position with a position of the display device detected by the position detector so as to calculate displacements of the display device in upward, downward, leftward, rightward, forward, and backward directions; when the display device is moved forward or backward, the controller enlarges or reduces the virtual screen displayed on the display device according to the calculated displacement in the forward or backward direction; and when the display device is moved upward, downward, leftward, or rightward, the controller controls the display device to display an upper, lower, left, or right region of the virtual screen according to the calculated displacement in the upward, downward, leftward, or rightward direction.

[6] The portable information terminal of claim 5, wherein the position detector is a gyro sensor.

[7] The portable information terminal of claim 5, wherein the position detector is a camera configured to capture images for obtaining information about upward, downward, leftward, and rightward movement of the display device from the captured images, wherein the camera captures images at regular intervals; a center portion of one of the images is set to a reference image; differences between the reference image and regions of a subsequent image are calculated to find a region of the subsequent image corresponding to the minimum of the calculated differences; a length from a center of the reference image to a center of the found region is calculated; and a direction and distance of movement of the display device is determined using the calculated length.

[8] The portable information terminal of claim 5, wherein the position detector is a camera configured to capture images for obtaining information about forward and backward movement of the display device from the captured images, wherein the camera captures images at regular intervals; a center portion of one of the images is set to a reference image; differences between the reference image and a corresponding region of a subsequent image are calculated while enlarging/reducing the corresponding region in steps so as to find a magnification ratio corresponding to the minimum of the calculated differences; and a displacement of the display device, and whether the display device moved forward or backward are determined using the magnification ratio.

[9] A method of manipulating a virtual mouse by moving a display device of a portable information terminal, the method comprising: fixing a mouse cursor to a predetermined position of the display device; moving the mouse cursor relative to a virtual screen by moving the display device upward, downward, leftward, or rightward; when the virtual cursor is placed on a click bar of the virtual screen, displaying the state of the virtual cursor placed on the click bar; and clicking the click bar using the virtual cursor by clicking an input unit of the portable information terminal.