Abstract:
A two side display device includes: a flexible substrate including a first substrate part, a second substrate part under the first substrate part, and a bending part coupling the first substrate part to the second substrate part; a first display panel on the first substrate part and configured to display a first image in a first direction; a second display panel under the second substrate part and configured to display a second image in a second direction opposite the first direction; and a driving chip coupled to the first substrate part. 
     According to exemplary embodiments, first and second display panels are positioned on the same surface of a flexible substrate and configured to display images in opposing directions by bending the flexible substrate, which may reduce the thickness and manufacturing cost of the two side display device.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2012-0119159 filed in the Korean Intellectual Property Office on Oct. 25, 2012, the entire content of which is incorporated herein by reference. 
     BACKGROUND 
     1. Field 
     The described technology relates generally to a two side display device and a manufacturing method thereof. 
     2. Description of the Related Art 
     A display device may include a liquid crystal display (LCD) or an organic light emitting diode (OLED) display capable of displaying an image on one surface of the display device. A two side display device is capable of displaying an image on two surfaces of the display device. 
     Two side display devices using an LCD may be made by positioning two display modules back-to-back, with each of the two display modules including a display panel, a backlight unit (BLU), and a driving chip (driver IC). Alternatively, a two side display device may include one BLU capable of emitting light in two directions to reduce the overall thickness of the two side display device. Further, a two side display device may include one BLU capable of emitting light in two directions and one driver IC, shared by two display panels that are connected by a flexible printed circuit (FPC). 
     However, two side display devices with two display panels are difficult to realize a thin thickness, and the process for attaching two display panels together increases manufacturing costs. 
     The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it 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 
     Exemplary embodiments according to the present invention provide a two side display device with a thin thickness and a low manufacturing cost and a manufacturing method thereof. 
     A two side display device according to an exemplary embodiment includes: a flexible substrate including a first substrate part, a second substrate part under the first substrate part, and a bending part coupling the first substrate part to the second substrate part; a first display panel on the first substrate part and configured to display a first image in a first direction; a second display panel under the second substrate part and configured to display a second image in a second direction opposite the first direction; and a driving chip coupled to the first substrate part. 
     An adhesion member may be between the first substrate part and the second substrate part. 
     The driving chip may be formed as a chip on film. 
     The first substrate part may include a first image display part and a first scan driver configured to transmit a first scan signal to the first image display part, the second substrate part may include a second image display part and a second scan driver configured to transmit a second scan signal to the second image display part, a the first scan driver may be coupled to the driving chip through a first scan connection line, and the second scan driver may be coupled to the first scan driver through a second scan connection line. 
     The driving chip may transmit a first scan driver start signal to the first scan driver and a second scan driver start signal to the second scan driver. 
     The first image display part and the second image display part may be coupled by a bending data line formed at the bending part. 
     A first light emission control driver may be configured to transmit a first light emission control signal to the first image display part, a second light emission control driver may be configured to transmit a second light emission control signal to the second image display part, and the first light emission control driver may be coupled to the driving chip through a first light emission control connection line, and the second light emission control driver may be coupled to the first light emission control driver through a second light emission control connection line. 
     The driving chip may be configured to transmit a first light emission control driver start signal to the first light emission control driver and a second light emission control driver start signal to the second light emission control driver. 
     A demux circuit may be between the driving chip and the first image display part. 
     The driving chip may be directly on the first substrate part. 
     A demux circuit may be between the driving chip and the first image display part. 
     A manufacturing method of a two side display device according to another exemplary embodiment includes: forming a first display panel and a second display panel at a first substrate part and a second substrate part, respectively, of a flexible substrate; coupling a driving chip to the first substrate part; and bending a bending part between the first substrate part and the second substrate part of the flexible substrate to position the second substrate part under the first substrate part. 
     The method may further include adhering the first substrate part and the second substrate part by an adhesion member. 
     The two side display device may include a first scan driver configured to transmit a first scan signal to the first image display part of the first substrate part, and a second scan driver configured to transmit a second scan signal to the second image display part of the second substrate part, wherein the first scan driver is coupled to the driving chip through a first scan connection line and the second scan driver is coupled to the first scan driver through a second scan connection line. 
     According to exemplary embodiments, the first display panel and the second display panel are on the same surface of a flexible substrate and configured to display images in opposing directions by bending the flexible substrate at a bending part of the flexible substrate, which may reduce the thickness and manufacturing cost of the two side display device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic cross-sectional view of a two side display device according to the first exemplary embodiment. 
         FIG. 2  is a schematic top plan view of a bending part of a two side display device according to the first exemplary embodiment before a bending. 
         FIG. 3  is a schematic cross-sectional view of a manufacturing method of a two side display device according to the first exemplary embodiment. 
         FIG. 4  is a schematic top plan view of a bending part of a two side display device according to the second exemplary embodiment before a bending. 
         FIG. 5  is a schematic cross-sectional view of a two side display device according to the third exemplary embodiment. 
         FIG. 6  is a schematic top plan view of a bending part of a two side display device according to the third exemplary embodiment before a bending. 
         FIG. 7  is a schematic top plan view of a bending part of a two side display device according to the fourth exemplary embodiment before a bending. 
     
    
    
     DETAILED DESCRIPTION 
     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 would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification. The size and thickness of each component shown in the drawings may have been exaggerated for clarity, understanding, and ease of description, but the present invention is not limited thereto. 
     Through the specification, it will be understood that when an element such as a layer, film, region, or substrate is referred to as being “on” another element, it can be directly on the other element or intervening elements may also be present. 
       FIG. 1  is a schematic cross-sectional view of a two side display device according to the first exemplary embodiment, and  FIG. 2  is a schematic top plan view of a bending part of a two side display device according to the first exemplary embodiment before a bending. 
     As shown in  FIG. 1 , a two side display device according to the first exemplary embodiment includes a flexible substrate  100  including a first substrate part  110 , a second substrate part  120  located (e.g. formed or positioned) under the first substrate part  110 , and a bending part  130  that is bent (e.g., curved or bowed) for connecting the first substrate part  110  to the second substrate part  120 . A first display panel  210  is positioned on the first substrate part  110  and is configured to display an image upward (i.e., in a direction away from the flexible substrate  100 ). A second display panel  220  is positioned under the second substrate part  120  and is configured to display an image downward (i.e., in a direction away from the flexible substrate  100 ). A driving chip  310  is positioned on a film  320  and connected to the first substrate part  110 . The chip  310  and the film  320  constitute a chip on film  300  (e.g., see  FIG. 3 ). 
     The first substrate part  110 , the bending part  130 , and the second substrate part  120  are continuously connected (e.g., formed as a single sheet or layer of material) thereby forming the flexible substrate  100 . 
     An adhesion member  1  is formed between the first substrate part  110  and the second substrate part  120  thereby adhering the first substrate part  110  and the second substrate part  120  to each other. 
     The first display panel  210  includes a first light emitting element  211 , a first encapsulation substrate  212  covering (e.g., encapsulating) the first light emitting element  211 , and a first polarizing plate  213  formed on the first encapsulation substrate  212  and improving outer visibility. 
     Also, the second display panel  220  includes a second light emitting element  221 , a second encapsulation substrate  222  covering (e.g., encapsulating) the second light emitting element  221 , and a second polarizing plate  223  attached to the second encapsulation substrate  222  and improving outer visibility. 
     The driving chip  310  is formed on a film  320 , and a flexible printed circuit (FPC)  400  is connected to the film  320 , which is an anisotropic conductive film (ACF). 
     As described above, in the two side display device according to an exemplary embodiment, the first display panel  210  and the second display panel  220  are both (e.g., simultaneously) positioned on the same surface (or same side) of a single flexible substrate  100  and the second display panel  220  is positioned under the first display panel  210  by bending the bending part  130  of the flexible substrate  100  such that the thickness of the two side display device is thin and the manufacturing process of the two side display device is simplified thereby reducing the manufacturing cost. 
     As shown in  FIG. 2 , the first substrate part  110  includes a first image display part  111  including a plurality of light emitting elements connected between scan lines and data lines in a matrix method to form a plurality of pixels, a first scan driver  112  transmitting the first scan signal SCAN 1  to the first image display part  111 , and a first light emission control driver  113  transmitting the first light emission control signal to the first image display part  111 . The first scan driver  112  and the first light emission control driver  113  process signals provided from the outside to generate the first scan signal SCAN 1  and the first light emission control signal EM 1 , and are formed in the manufacturing process of the light emitting element or are formed of an additional driving chip  310 , and are mounted on the first substrate part  110 . The driver formed in the first substrate part  110  is not limited to the first scan driver  112  and the first light emission control driver  113 , and the first light emission control driver  113  may be formed externally with respect to the first substrate part  110 . 
     The second substrate part  120  includes a second image display part  121 , a second scan driver  122  transmitting the second scan signal SCAN 2  to the second image display part  121 , and a second light emission control driver  123  transmitting the second light emission control signal EM 2  to the second image display part  121 . The second scan driver  122  and the second light emission control driver  123  process signals provided from the outside to generate the second scan signal SCAN 2  and the second light emission control signal EM 2  and are formed in the manufacturing process of the light emitting element or are formed of an additional driving chip  310 , and are mounted on the first substrate part  120 . The driver formed in the second substrate part  120  is not limited to the second scan driver  122  and the second light emission control driver  123 , and the second light emission control driver  123  may be formed externally with respect to the second substrate part  120 . 
     The first scan signal SCAN 1  is a signal for switching to transmit the data signal DAT to the first image display part  111 , the first light emission control signal EMI is a signal for controlling light emitted from the first image display part  111 , the second scan signal SCAN 2  is a signal for switching to transmit the data signal DAT to the second image display part  121 , and the second light emission control signal EM 2  is a signal for controlling the light emitted from the second image display part  121 . 
     The first scan driver  112  is connected to the driving chip  310  through a first scan connection line  10 , and the first light emission control driver  113  is connected to the driving chip  310  through a first light emission control connection line  30 . Also, the second scan driver  122  is connected to the first scan driver  112  through a second scan connection line  20 , and the second scan driver  122  is again connected to the driving chip  310  through the first scan driver  112  and the first scan connection line  10 . Further, the second light emission control driver  123  is connected to the first light emission control driver  113  through a second light emission control connection line  40 , and the second light emission control driver  123  is again connected to the driving chip  310  through the first light emission control driver  113  and the first light emission control connection line  30 . The second scan driver  122  or the second light emission control driver  123  may be directly connected to the driving chip  310  through an additional signal line. 
     The second scan connection line  20  and the second light emission control connection line  40  are formed at the bending part  130 . 
     The first image display part  111  and the second image display part  121  are connected by the bending data line  60  formed at the bending part  130 . The data signal DAT generated in the driving chip  310  is transmitted to the first image display part  111  through a driving data line  50 , and the data signal DAT passing through the second image display part  121  is transmitted to the second image display part  121  through a bending data line  60 . 
     A demux circuit  500  increasing a channel of the driving chip  310  is formed between the driving chip  310  and the first image display part  111 . The driving data line  50  includes a demux input terminal  51  connecting the channel of the driving chip  310  and the demux circuit  500  and a demux output terminal  52  connecting the first image display part  111  and the demux circuit  500 . A number of demux output terminals  52  is greater than a number of demux input terminals  51 . 
     The driving chip  310  independently transmits the first scan driver start signal FLM1 to the first scan driver  112 , and the second scan driver start signal FLM2 to the second scan driver  122  to independently control the operation of the two scan drivers. 
     Also, the driving chip  310  independently transmits the first light emission control driver start signal EM_FLM 1  to the first light emission control driver  113 , and the second light emission control driver start signal EM_FLM 2  to the second light emission control driver  123 , to independently control the operation of the two light emission control drivers. 
     Accordingly, the driving chip  310  may independently control the driving of the first display panel  210  and the second display panel  220 . Accordingly, the first display panel  210  and the second display panel  220  may independently or simultaneously display the image. 
     For example, when the first display panel  210  displays the image, the first scan driver start signal and the first light emission control driver start signal EM_FLM 1  are operated, but the second scan driver start signal and the second light emission control driver start signal EM_FLM 2  are not operated such that the first display panel  210  displays the image and the second display panel  220  does not display the image. 
     Alternatively, when the second display panel  220  displays the image, the second scan driver start signal and the second light emission control driver start signal EM_FLM 2  are operated, but the first scan driver start signal and the first light emission control driver start signal EM_FLM 1  are not operated such that the second display panel  220  displays the image and the first display panel  210  does not display the image. 
     Alternatively, the first display panel  210  and the second display panel  220  may both display the same image concurrently (e.g., simultaneously) or sequentially, such that the first scan driver start signal and the first light emission control driver start signal EM_FLM 1 , and the second scan driver start signal and the second light emission control driver start signal EM_FLM 2 , are operated such that the first display panel  210  and the second display panel  220  concurrently (e.g., simultaneously) display the image or sequentially display the image. 
     Next, a manufacturing method of the two side display device according to the first exemplary embodiment will be described with reference to  FIG. 1  through  FIG. 3 . 
       FIG. 3  is a schematic cross-sectional view of a manufacturing method of a two side display device according to the first exemplary embodiment. 
     Firstly, as shown in  FIG. 2  and  FIG. 3 , the first display panel  210  and the second display panel  220  are respectively formed over the first substrate part  110  and the second substrate part  120  of the flexible substrate  100 . 
     Also, the film  320 , including the driving chip  310  mounted over the film  320 , is connected to the first substrate part  110 . As shown in  FIG. 2 , the first scan driver  112  is connected to the driving chip  310  through the first scan connection line  10 , and the second scan driver  122  is connected to the first scan driver  112  through the second scan connection line  20 . The first light emission control driver  113  is connected to the driving chip  310  through the first light emission control connection line  30 , and the second light emission control driver  123  is connected to the first light emission control driver  113  through the second light emission control connection line  40 . 
     Next, as shown in  FIG. 1 , the bending part  130  is bent between the first substrate part  110  of the flexible substrate  100  and the second substrate part  120  for the second substrate part  120  to be positioned under the first substrate part  110 . 
     Also, the first substrate part  110  and the second substrate part  120  are adhered by the adhesion member  1 . 
     As described above, in the manufacturing method of the two side display device according to an exemplary embodiment, the first display panel  210  and the second display panel  220  are both formed on the same surface (or same side) of a single flexible substrate  100  and the second display panel  220  is positioned under the first display panel  210  by bending the bending part  130  of the flexible substrate  100  such that the thickness of the two side display device is thin and the manufacturing process of the two side display device is simplified thereby reducing the manufacturing cost. 
     Meanwhile, in the first exemplary embodiment, the demux circuit is formed, however a second exemplary embodiment without the demux circuit is possible. 
       FIG. 4  is a top plan view of a bending part of a two side display device according to the second exemplary embodiment before bending. 
     As shown in  FIG. 4 , the data signal DAT generate in the driving chip  310  of the two side display device according to the second exemplary embodiment is transmitted to the first image display part  111  through the driving data line  50 , and the data signal DAT passing through the second image display part  121  is transmitted to the second image display part  121  through the bending data line  60 . In the two side display device of high resolution, the driving chip  310  has a sufficient number of channels such that the separate demux circuit  500  is not necessary. 
     Meanwhile, the driving chip  310  is mounted on the chip on film in the first exemplary embodiment, however a third exemplary embodiment of a structure of a chip on glass in which the driving chip  310  is directly mounted on the first substrate part is possible. 
     Next, the third exemplary embodiment will be described with reference to  FIG. 5  and  FIG. 6 . 
       FIG. 5  is a schematic cross-sectional view of a two side display device according to the third exemplary embodiment, and  FIG. 6  is a schematic top plan view of a bending part of a two side display device according to the third exemplary embodiment before a bending. 
     The third exemplary embodiment shown in  FIG. 5  and  FIG. 6  is similar to the first exemplary embodiment shown in  FIG. 1  to  FIG. 3  except for the chip on glass such that the repeated description is omitted. 
     As shown in  FIG. 5  and  FIG. 6 , in the two side display device according to the third exemplary embodiment, the driving chip  310  is directly mounted on the first substrate part  110 . Accordingly, the separate film  320  is not necessary such that the structural area occupied by the film  320  may be omitted, thereby reducing the thickness and the volume of the two side display device. 
     Meanwhile, the demux circuit  500  is formed in the third exemplary embodiment, as shown in  FIG. 6 . However a fourth exemplary embodiment without the demux circuit is possible. 
       FIG. 7  is a schematic top plan view of a bending part of a two side display device according to the fourth exemplary embodiment before bending. 
     As shown in  FIG. 7 , the data signal DAT generated in the driving chip  310  that is directly mounted at the first substrate part  110  of the two side display device according to the fourth exemplary embodiment is transmitted to the first image display part  111  through the driving data line  50 , and the data signal DAT passing through the second image display part  121  is transmitted to the second image display part  121  through the bending data line  60 . The driving chip  310 , which includes a large number of channels, is used in the two side display device of the high resolution such that the separate demux circuit is not necessary. 
     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, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. 
     
       
         
               
             
               
               
               
             
           
               
                   
               
               
                 &lt;Description of Symbols&gt; 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 100: flexible substrate 
                 110: first substrate part 
               
               
                   
                 120: second substrate part 
                 130: bending part 
               
               
                   
                 210: first display panel 
                 220: second display panel 
               
               
                   
                 300: chip on film 
                 310: driving chip 
               
               
                   
                 320: film 
                 400: flexible printed circuit (FPC)