Abstract:
A display device includes: a flexible display panel including a recognition pattern; a housing for holding the flexible display panel, wherein varying amounts of a display area of the flexible display panel are exposable to the outside to display an image; and a sensor in the housing for sensing an amount of the exposed display area corresponding to the recognition pattern.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2011-0079674 filed in the Korean Intellectual Property Office on Aug. 10, 2011, the entire content of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     The described technology relates generally to a display device. More particularly, the described technology relates to a display device including a flexible display panel. 
     2. Description of Related Art 
     A display device is a device for displaying an image, and flexible display devices have recently been more widely developed and implemented in various devices and applications. 
     A conventional flexible display device is a device including a flexible display panel for displaying an image, and can be more portable because the size of the flexible display can be reduced by being folded or rolled. 
     The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology, and therefore, may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
     SUMMARY OF THE INVENTION 
     The described technology has been made in an effort to provide a display device for displaying an image that has optimized or improved characteristics in view of the flexibility of a flexible display panel. 
     One aspect of an exemplary embodiment of the present invention provides a display device including: a flexible display panel including a recognition pattern; a housing for holding the flexible display panel, wherein varying amounts of a display area of the flexible display panel are exposable to the outside to display an image; and a sensor in the housing for sensing an amount of the exposed display area corresponding to the recognition pattern. 
     The display device may further include a controller connected with the sensor and the flexible display panel for displaying an image corresponding to the amount of the exposed display area sensed by the sensor. 
     The flexible display panel may further include a non-display area neighboring the display area, wherein the recognition pattern may be in the non-display area. 
     The flexible display panel may be configured to enter and exit the housing along a first direction, and the recognition pattern may be formed in the flexible display panel along the first direction. 
     The recognition pattern may include first sub-patterns for absorbing light and second sub-patterns for reflecting light that are alternately arranged along the first direction, and the sensor may include a photo sensor including a light emitting portion and a light receiving portion neighboring each other. 
     The recognition pattern may include a bar code and the sensor may be configured to read or recognize the bar code. 
     The recognition pattern may include an ideogram and the sensor may be configured to read or recognize the ideogram. 
     The recognition pattern may include first sub-patterns for transmitting light and second sub-patterns for blocking light, wherein the first sub-patterns and the second sub-patterns are alternately arranged along the first direction, and the sensor may include a photo sensor including a light emitting portion and a light receiving portion that are arranged on opposite sides of the recognition pattern. 
     The housing may include a roll portion in the housing for rolling or storing the flexible display panel. 
     According to exemplary embodiments of the present invention, a display device that can display an image optimized to the characteristic of flexibility of the flexible display panel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a display device according to a first exemplary embodiment; 
         FIG. 2  shows a flexible display panel of the display device according to the first exemplary embodiment; 
         FIG. 3  is provided to describe a sensing method of the display device according to the first exemplary embodiment; 
         FIG. 4  shows an image that the flexible display panel of the display device according to the first exemplary embodiment displays; 
         FIG. 5  shows a flexible display panel of a display device according to a second exemplary embodiment; 
         FIG. 6  shows a flexible display panel of a display device according to a third exemplary embodiment; 
         FIG. 7  shows a flexible display panel of a display device according to a fourth exemplary embodiment; and 
         FIG. 8  is provided to describe a sensing method of the display device according to the fourth exemplary embodiment. 
         FIG. 9  shows a display device according to another embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The present invention will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. As those skilled in the art will recognize, the described embodiments may be modified in various different ways without departing from the spirit or scope of the present invention. 
     In order to more clearly describe the embodiments, parts that are not related to the description thereof will be omitted. In addition, like reference numerals designate like elements throughout the specification. 
     Elements having the same or similar structures throughout the embodiments are denoted by the same reference numerals and are described in a first exemplary embodiment. In subsequent exemplary embodiments, only the elements other than the same or similar elements from previous embodiments will be described in greater detail. 
     In addition, the size and thickness of each component shown in the drawings are arbitrarily shown for understanding and ease of description, but the present invention is not limited thereto. 
     In the drawings, the thickness of layers, films, panels, regions, etc., are exaggerated for clarity. In addition, in the drawings, for understanding and ease of description, the thicknesses of some layers and areas are exaggerated. It will also be understood that when an element is referred to as being “on” another element, it can be directly on the other element, or one or more intervening elements may also be present. 
     In addition, throughout the specification, “on” implies being positioned above or below a target element, and does not necessarily imply being positioned on top based on, for example, a gravitational direction. 
     Hereinafter, a display device according to a first exemplary embodiment will be described with reference to  FIG. 1  to  FIG. 4 . 
     As shown in  FIG. 1 , the display device according to the first exemplary embodiment includes a flexible display panel  100 , a housing  200 , a sensor  300 , and a controller  400 . 
     The flexible display panel  100  displays an image processed in the display device. For example, if the display device is provided as a portable terminal such as a mobile phone, the flexible display panel  100  may display an image such as a user interface (IU) or a graphic user interface (GUI). The flexible display panel  100  may include flexible substrates or films arranged opposite to each other, with interposing liquid crystals or organic light emitting diodes therebetween. The flexible display panel  100  may be a transparent or light transmissive type display panel, through which it is possible to view the outside or other side. On a top side of the flexible display panel  100 , a touch sensor provided as a touch film, a touch sheet, or a touch pad may be provided to sense touch operations. The flexible display panel  100  is connected with the controller  400 , and displays an image using a signal transmitted from the controller  400 . The flexible display panel  100  has flexibility, and may be put or retracted into or taken out of the housing  200 . The flexible display panel  100  may be put into and taken out of the housing  200  along a first direction, and a display area of the flexible display panel  100  is variably exposed to the outside. 
       FIG. 2  shows the flexible display panel of the display device according to the first exemplary embodiment. 
     As shown in  FIG. 2 , the flexible display panel  100  includes a display area DA for displaying an image, a non-display area NDA neighboring the display area DA, and a recognition pattern  110  disposed on the non-display area NDA. 
     In the display device according to the first exemplary embodiment, the display area DA and the non-display area NDA may be disposed on a top or first side of the flexible display panel  100 , but the present invention is not limited thereto. For example, the display area DA may be disposed on the top side of the flexible display panel  100 , while the non-display area NDA may be disposed on the bottom or second side of the flexible display panel  100 . In other words, when an image is displayed on the top side of the flexible display panel  100 , the recognition pattern  110  may be disposed on the bottom side or on the top side of the flexible display panel  100  according to different embodiments. 
     The recognition pattern  110  of the display device according to the first exemplary embodiment is disposed in the non-display area NDA, but a recognition pattern of a display device according to another exemplary embodiment may instead be disposed in a display area DA where an image is displayed, as shown in  FIG. 9 , for example. 
     The recognition pattern  110  (or  110 ′) may also be disposed between two neighboring substrates, and it may be formed simultaneously when a wire or a touch sensor of the flexible display panel  100  (or  100 ′) is formed. The recognition pattern  110  (or  110 ′) is arranged along a first direction along which the flexible display panel  100  (or  100 ′) is put into or taken out of the housing  200 . The recognition pattern  110  (or  110 ′) includes first sub-patterns  111  (or  111 ′) and second sub-patterns  112  (or  112 ′) that are alternately arranged along the first direction. The first sub-pattern  111  (or  111 ′) may have a black color for absorbing light and the second sub-pattern  112  (or  112 ′) may have a white color for reflecting light. 
     Referring back to  FIG. 1 , the housing  200  supports one end of the flexible display panel  100 , and receives or discharges the flexible display panel  100 , so that the display area of the flexible display panel  100  is variably exposed. The housing  200  includes a roll portion  210  around which the flexible display panel  100  can be rolled. The roll portion  210  is disposed in the housing  200  and supports one end of the flexible display panel  100 . The roll portion  210  rolls the flexible display panel  100  clockwise or counterclockwise, to allow the housing  200  to receive or discharge the flexible display panel  100  along the first direction. The roll portion  210  is rotatable in a passive or active manner, and the flexible display panel  100  can be put into or taken out of the housing  200  along the first direction as the roll portion  210  rotates. The sensor  300  may also be disposed in the housing  200 . 
       FIG. 3  is provided for describing a sensing method of the display device according to the first exemplary embodiment. 
     As shown in  FIG. 3 , the sensor  300  is disposed in the housing  200 , and may correspond to the recognition pattern  110  disposed in the non-display area NDA of the flexible display panel  100 . The sensor  300  may sense an amount of display area of the flexible display panel  100  that is exposed to the outside as the flexible display panel  100  is discharged from the housing  200 , by for example, detecting and recognizing the recognition pattern  110 . 
     The sensor  300  is a photo sensor including a first light emission portion  310  and a first light receiving portion  320  that may be arranged to be adjacent to each other. 
     The first light emission portion  310  emits light toward the recognition pattern  110 , and the first light receiving portion  320  receives the light that is emitted from the first light emission portion  310  and then reflected by the recognition pattern  110 . 
     The sensor  300  senses an amount of the display area of the flexible display panel  100  that is exposed to the outside as the flexible display panel  100  is discharged from the housing  200 , by recognizing the recognition pattern  110  using the first light emission portion  310  and the first light receiving portion  320 . Particularly, as shown in  FIG. 3(   b ), when the flexible display panel  100  enters or exits the housing  200  along the first direction, light emitted from the first light emission portion  310  is reflected only by the second sub-pattern  112  of the recognition pattern  110  and then recognized by the first light receiving portion  320 . Accordingly, the sensor  300  can count a number of second sub-patterns  112  recognized by the first light receiving portion  320 , to sense the amount of the display area of the flexible display panel  100  exposed to the outside, as the flexible display panel  100  is discharged from the housing  200  along the first direction. A signal related to the exposed display area of the flexible display panel  100 , and sensed by the sensor  300 , may be transmitted to the controller  400 . 
       FIG. 4  shows an image displayed by the flexible display panel of the display device according to the first exemplary embodiment. 
     As shown in  FIG. 4 , the controller  400  is connected with the sensor  300  and the flexible display panel  100 , and adjusts and displays an image corresponding to an amount of exposed display area of the flexible display panel  100  sensed by the sensor  300  through the flexible display panel  100 . 
     Particularly, as shown in  FIG. 4(   a ), when a first length of the flexible display panel  100  is discharged from the housing  200  along the first direction, where a first display area DS 1  is exposed, the sensor  300  senses the first display area DS 1  and transmits a signal adjusted for the display area DS 1  to the controller  400 . The controller  400  receives the signal and displays an image having a first size corresponding to the first display area DS 1  of the flexible display panel  100 . 
     In addition, as shown in  FIG. 4(   b ), when a second length of the flexible display panel  100  is discharged from the housing  200  along the first direction, where a second display area DS 2  that is larger than the first display area DS 1  is exposed, the sensor  300  senses the second display area DS 2  and transmits a signal adjusted for the second display area DS 2  to the controller  400 . The controller  400  receives the signal and displays an image having a second size corresponding to the second display area DS 2  of the flexible display panel  100 . 
     Further, as shown in  FIG. 4(   c ), when a third length of the flexible display panel  100  is discharged from the housing  200  along the first direction, where a third display area DS 3  that is larger than the second display area DS 2  is exposed, the sensor  300  senses the third display area DS 3  and transmits a signal adjusted for the third display area DS 3  to the controller  400 . The controller  400  receives the signal and displays an image having a third size corresponding to the third display area DS 3  of the flexible display panel  100 . 
     As described above, in the display device according to the first exemplary embodiment, the sensor  300  recognizes the recognition pattern  110  formed in the flexible display panel  100  to sense the amount of the display area of the flexible display panel  100  exposed to the outside, and an image corresponding to the exposed display area is displayed on or through the flexible display panel  100 , so that the image can be optimized for characteristics of flexibility of the flexible display panel  100  based on, for example, an exposed display area. 
     In particular, the display device according to the first exemplary embodiment recognizes the recognition pattern  110  formed in the flexible display pattern  100  using the sensor  300  to sense an amount of the display area of the flexible display panel  100  exposed to the outside as the flexible display panel  100  is discharged from the housing  200 , and as such, the amount of display area can be accurately sensed even though the exposed portion is non-linearly twisted. 
     That is, the display device according to the first exemplary embodiment senses the display area of the flexible display panel  100  exposed to the outside using the sensor  300 , which recognizes the recognition pattern  110  when the flexible display panel  100  is put into or taken out of the housing  200  in real time, rather than sensing the entire area of the flexible display panel  100  after the flexible display panel  100  is taken out of the housing  200 . Thus, even though the exposed portion of the flexible display panel  100  is non-linearly twisted due to the characteristics of flexibility, an image having a size corresponding to the exposed display area of the flexible display panel  100  can be displayed by accurately sensing the exposed display area in such a manner. 
     Further, the display device according to the first exemplary embodiment senses the exposed display area of the flexible display panel  100  by recognizing the recognition pattern  110  formed in the flexible display panel  100  in real time in the above manner, rather than indirectly sensing the display area of the flexible display panel  100  by, for example, counting a number of rotations of the roll portion  210  or sensing the display area of the flexible display panel  100  after it is rolled out using a distance measurement means, such as using infrared rays or ultrasonic waves. Accordingly, an image having an accurate size that corresponds to the variable display area of the flexible display panel  100  is variably displayed by the flexible display panel  100 . This may act, for example, as a factor for improving satisfaction of a user of the display device. 
     A display device according to a second exemplary embodiment will be described with reference to  FIG. 5 . 
       FIG. 5  shows a flexible display panel of the display device according to the second exemplary embodiment. 
     As shown in  FIG. 5 , a flexible display panel  102  of the display device according to the second exemplary embodiment includes a display area DA for displaying an image, a non-display area NDA neighboring the display area DA, and a recognition pattern  120  in the non-display area NDA. 
     The recognition pattern  120  may be arranged on a top or a bottom side of the flexible display panel  102 , or may be between two neighboring substrates, and the recognition pattern  120  may be formed substantially simultaneously as when a wire or a touch sensor of the flexible display panel  102  is formed. The recognition pattern  120  is arranged along a first direction along which the flexible display panel  102  is put or retracted into or taken out of a housing  200 . The recognition pattern  120  has a shape of, for example, a bar code arranged along the first direction. 
     The sensor  300  senses an amount of display area of the flexible display panel  102  exposed to the outside as the flexible display panel  102  is discharged from the housing  200  by recognizing specific portions of the bar code of the recognition pattern  120 . 
     Particularly, when the flexible display panel  102  is discharged from the housing  200  along the first direction, the sensor  300  scans the bar code of the recognition pattern  120  to sense the amount of currently exposed display area according to the recognition pattern  120 . 
     As described above, the recognition pattern  120  has the shape of a bar code, and the sensor  300  scans the bar code of the recognition pattern  120  to sense an amount of the currently exposed display area of the flexible display panel  102 , to thereby display an image corresponding to the amount of exposed display area on the flexible display panel  102 . Therefore, the display device according to the second exemplary embodiment can also provide an image optimized for characteristics of flexibility of the flexible display panel  102  based on, for example, an exposed display area. 
     Hereinafter, a display device according to a third exemplary embodiment will be described with reference to  FIG. 6 . 
       FIG. 6  shows a flexible display panel of the display device according to the third exemplary embodiment. 
     As shown in  FIG. 6 , a flexible display panel  103  of the display device according to the third exemplary embodiment includes a display area DA, a non-display area NDA neighboring the display area DA, and a recognition pattern  130  in the non-display area NDA. 
     The recognition pattern  130  may be arranged on an upper or a bottom side of the flexible display panel  103 , or may be between two neighboring substrates, and may be formed substantially simultaneously as when a wire or touch sensor of the flexible display panel  103  is formed. The recognition pattern  130  is arranged along a first direction along which the flexible display panel  103  is put or retracted into or taken out of the housing  200 . The recognition pattern  130  has a shape (e.g., a predetermined shape) of an ideogram along the first direction. 
     The sensor  300  senses an amount of display area of the flexible display panel  103  exposed to the outside as the flexible display panel  103  is discharged from the housing  200  by recognizing the ideogram of the recognition pattern  130 . 
     Particularly, when the flexible display panel  103  is put into or discharged from the housing  200  along the first direction, the sensor  300  scans the ideogram of the recognition pattern  130  to sense the amount of currently exposed display area of the flexible display panel  103 . For example, if the predetermined ideogram of the recognition pattern  130  is represented by Arabic numerals, and when the sensor  300  scans Arabic numeral “5”, the display area of the flexible display panel  103  exposed to the outside corresponds to a fifth step, and the flexible display panel  103  may display an image having a size corresponding to the fifth step. 
     As described above, according to the third exemplary embodiment, the recognition pattern  130  includes an ideogram, and the sensor  300  scans the ideogram of the recognition pattern  130  to sense an amount of the currently exposed display area of the flexible display panel  103 , and thus an image corresponding to the currently exposed display area can be displayed on the flexible display panel  103 . Accordingly, the display device can display an image optimized for characteristics of flexibility of the flexible display panel  103  based on, for example, an exposed display area. 
     Hereinafter, a display device according to a fourth exemplary embodiment will be described with reference to  FIG. 7  and  FIG. 8 . 
       FIG. 7  shows a flexible display panel of the display device according to the fourth exemplary embodiment. 
     As shown in  FIG. 7 , a flexible display panel  104  includes a display area DA for displaying an image, a non-display area NDA neighboring the display area DA, and a recognition pattern  140  in the non-display area NDA. 
     The recognition pattern  140  may be arranged on an upper or a bottom side of the flexible display panel  104 , or may be between two neighboring substrates, and the recognition pattern  140  may be formed substantially simultaneously as when a wire or touch sensor of the flexible display panel  104  is formed, or may be formed in an additional window that can protect the flexible display panel  104 . The recognition pattern  140  is arranged along a first direction along which the flexible display panel  104  is put or retracted into or taken out of a housing  200 . The recognition pattern  140  includes third sub-patterns  141  and fourth sub-patterns  142  alternately arranged along the first direction. The third sub-pattern  141  may be made of a transparent material that transmits light or may be a hole, and the fourth sub-pattern  142  may be made of an opaque material that blocks light. 
       FIG. 8  is provided for description of a sensing method of the display device according to the fourth exemplary embodiment. 
     As shown in  FIG. 8 , a sensor  304  is positioned in the housing  200  corresponding to the recognition pattern  140  in the non-display area NDA. The sensor  304  senses an amount of display area of the flexible display panel  104  exposed to the outside as the flexible display panel  104  is discharged from the housing  200 . 
     The sensor  304  may be a photo sensor including a second light emitting portion  330  and a second light receiving portion  340  that are arranged opposite to each other, with the recognition pattern  140  interposed therebetween. 
     The second light emitting portion  330  emits light toward the recognition pattern  140 , and the second light receiving portion  340  receives light that is emitted from the second light emitting portion  330  and that passes through the recognition pattern  140 . 
     The sensor  304  recognizes the recognition pattern  140  using the second light emitting portion  330  and the second light receiving portion  340  to sense an amount of the display area of the flexible display panel  104  exposed to the outside as the flexible display panel  104  is discharged from the housing  200 . Particularly, when the flexible display panel  104  is discharged from the housing  200  along the first direction, light emitted from the second light emitting portion  330  only passes through the third sub-patterns  141  of the recognition pattern  140 , to then be recognized by the second light receiving portion  340 . Therefore, the sensor  304  counts the number of third sub-patterns  141  recognized by the second light receiving portion  340 , to sense and determine an amount of the display area exposed to the outside as the flexible display panel  104  is discharged from the housing  200 . A signal related to the amount of exposed display area of the flexible display panel  104 , sensed by the sensor  304 , may be transmitted to a controller  400 . 
     As described, the display device  304  according to the fourth exemplary embodiment senses the amount of display area of the flexible display panel  104  exposed to the outside as the flexible display panel  104  is put into or taken out of the housing  200 , by recognizing the recognition pattern  140  in the flexible display panel  104  using the sensor  140 . The flexible display panel  104  can then display an image corresponding to the amount of exposed display area. Accordingly, the image displayed by the flexible display panel  104  can be optimized for characteristics of flexibility of the flexible display panel  104  based on, for example, an exposed display area. 
     While this disclosure has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is instead intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.