ROLLABLE DISPLAY
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`CROSS-REFERENCE TO RELATED APPLICATIONS
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`[0001]
`
`This application is a continuation of U.S. Patent Application Serial No. 15/404,155
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`filed on January 11, 2017, which claims the priority benefit of Republic of Korea Patent
`
`Application No. 10-2016-0052725 filed on April 29, 2016, which are hereby incorporated
`
`herein by reference for all purposes as if fully set forth herein.
`
`Field of the Invention
`
`BACKGROUND
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`[0002]
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`The present invention relates to a rollable display.
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`Discussion of the Related Art
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`[0003] With the development of information technology, the market for displays, which
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`act as an intermediary between users and information, is growing. Thus, display devices such
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`as organic light-emitting displays (OLEDs),
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`liquid crystal displays (LCDs), and plasma
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`display panels (PDPs) are increasingly used.
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`[0004]
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`Among the above-explained display devices, an organic light-emitting display
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`comprises a flexible display panel comprising a plurality of subpixels and a drive part that
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`drives the flexible display panel. The drive part comprises a scan driver that supplies a scan
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`signal (or gate signal) to the flexible display panel, a data driver that supplies a data signal to
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`the flexible display panel, etc.
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`[0005]
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`Since the organic light-emitting display offers flexibility, the flexible display panel
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`can be bent or curved and the shape of the flexible display panel can be changed by rolling
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`and unrolling it like a scroll. For this reason, more and more attempts are being made to
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`

`

`design the flexible display panel of the organic light-emitting display and a mechanical
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`structure for holding it in various shapes.
`
`SUMMARY
`
`[0006] Embodiments relate to a rollable display comprising a flexible display panel, a
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`reinforcing structure, a roller, a printed circuit board, a control board and a connecting
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`member. The flexible display panel has pixels to display an image on a front side of the
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`flexible display panel. The reinforcing structure is attached to a rear side of the flexible
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`display panel and includes a plurality of segments with through holes. The roller is attached
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`to one end of the flexible display panel and has a circumference surface onto which the
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`flexible display panel is rolled. The printed circuit board is on the flexible display pane. The
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`control board is in the roller. The connecting member connects the control board to the
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`printed circuit board, the connecting member slidably inserted into the through holes.
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`[0007] In one embodiment, the rollable display further includes an auxiliary sheet between an
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`end of the flexible display panel to the roller to couple the flexible display panel to the roller.
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`[0008] In one embodiment, each of the segments has a shape of a bar that extends in a first
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`direction and is arranged side by side in a second direction perpendicular to the first direction.
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`[0009] In one embodiment, adjacent segments are spaced apart by a set distance.
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`[0010] In one embodiment, a buffering member is provided in at least part of an inside
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`surface of a through hole of a segment.
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`[0011] In one embodiment, each of the segments includes an attaching surface bonded to the
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`flexible display panel, and an attached surface opposite the attaching surface. The surface
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`between the attaching surface and the attached surface has a predetermined curvature.
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`

`

`[0012] In one embodiment, each of the segments includes an attaching surface bonded to the
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`flexible display panel, and an attached surface opposite the attaching surface. The rollable
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`display further includes a buffering member bonded to the attached surface.
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`[0013] In one embodiment, at least one of the segments further includes a recess having a
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`shape of a hole or the shape of a groove.
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`[0014] In one embodiment, the rollable display further includes at least another connecting
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`member. Each of the segments of the reinforcing structure includes at least another through
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`hole. At least another connecting member is inserted into the at least another through hole.
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`[0015] In one embodiment, the rollable display further includes an adhesive member that
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`fixes part of the connecting member to at least one side of the control board.
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`[0016] In one embodiment, the rollable display further includes a support block provided
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`between the flexible display panel and the printed circuit board, and a cover holder that is
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`bonded to the support block and accommodates part of the connecting member.
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`[0017] In one embodiment, each of the segments comprises a front case bonded to the rear
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`side of the flexible display panel, a rear case placed opposite the front case, and at least one
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`middle case placed between the front case and the rear case. A through hole is an internal
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`space between the front case, rear case, and middle case.
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`[0018] In one embodiment, each of the segments is attached to a rear surface of the flexible
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`display panel via one or more adhesive films.
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`[0019] In one embodiment, a substrate of the flexible display panel includes a first section of
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`a first thickness and a second section of a second thickness thicker than the first thickness.
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`The second section is provided at an end of the flexible display panel that is located away
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`from the roller.
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`[0020] In one embodiment, the flexible display panel includes a glass substrate and a metal
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`substrate, and the metal substrate having a larger area than the glass substrate.
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`3
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`

`

`[0021] Embodiments also relate to a rollable display including a flexible display panel, a
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`flexible display panel, a reinforcing structure, a roller, a printed circuit board, a control board,
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`a connecting member and at least one buffer member. The flexible display panel has pixels
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`to display an image on a front side of the flexible display panel. The reinforcing structure is
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`attached to a rear side of the flexible display panel and comprising a plurality of segments.
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`The roller is attached to one end of the flexible display panel and has a circumference surface
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`onto which the flexible display panel is rolled. The printed circuit board is on the flexible
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`display panel. The control board is in the roller. The connecting member connects the control
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`board to the printed circuit board. At least one buffer member is attached to the reinforcing
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`structure.
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`[0022] In one embodiment, the at least one buffer member is a foam tape or a foam board.
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`[0023] In one embodiment, the rollable display further includes an auxiliary sheet between an
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`end of the flexible display panel to couple the flexible display panel to the roller.
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`BRIEF DESCRIPTION OF THE DRAWINGS
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`[0024]
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`The accompanying drawings, which are included to provide a further understanding
`
`of the invention and are incorporated in and constitute a part of this specification, illustrate
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`embodiments of the invention and together with the description serve to explain the
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`principles of the invention. In the drawings:
`
`[0025]
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`FIG. 1 is a schematic block diagram of an organic light-emitting display according
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`to an exemplary embodiment of the present invention;
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`[0026]
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`FIG. 2 is a schematic view showing the circuit configuration of a subpixel of FIG.
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`1;
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`[0027]
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`FIG. 3 illustrates an example of the configuration of a subpixel according to an
`
`exemplary embodiment of the present invention;
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`4
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`

`

`[0028]
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`FIG. 4 illustrates the top plane of a flexible display panel according to an
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`exemplary embodiment of the present invention;
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`[0029]
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`FIG. 5 illustrates a cross-section of the flexible display panel according to the
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`exemplary embodiment of the present invention;
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`[0030]
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`FIGS. 6A and 6B are cross-sectional views showing an example of etching a first
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`substrate;
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`[0031]
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`FIG. 7 is a cross-sectional view showing an example of joining a first substrate and
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`a second substrate, according to one embodiment;
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`[0032]
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`FIG. 8 is a top plan view showing a flexible display panel implemented as a
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`module;
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`[0033]
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`FIGS. 9A and 9B are views showing a rollable display according to an exemplary
`
`embodiment of the present invention;
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`[0034]
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`FIG. 10 is a perspective view showing a flexible display panel and a roller;
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`[0035]
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`FIGS. 11A through 12 are views for explaining the basic structure of the rollable
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`display panel;
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`[0036]
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`FIGS. 13 through 18B are views for explaining a first exemplary embodiment of
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`the present invention;
`
`[0037]
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`FIGs. 19A and 19B is a cross-sectional view for explaining a second exemplary
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`embodiment of the present invention;
`
`[0038]
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`FIGS. 20A through 21 are views for explaining a third exemplary embodiment of
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`the present invention;
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`[0039]
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`FIG. 22 is a view for explaining a fourth exemplary embodiment of the present
`
`invention;
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`[0040]
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`FIG. 23 is a cross-sectional view for explaining a fifth exemplary embodiment of
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`the present invention;
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`

`

`[0041]
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`FIG. 24 is a cross-sectional view for explaining a sixth exemplary embodiment of
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`the present invention;
`
`[0042]
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`FIGS. 25A and 25B are perspective views for explaining a seventh exemplary
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`embodiment of the present invention.
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`DETAILED DESCRIPTION
`
`[0043]
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`Reference will now be made in detail
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`to embodiments
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`illustrated in the
`
`accompanying drawings, examples of which are illustrated in the accompanying drawings.
`
`Wherever possible, the same reference numbers will be used throughout the drawings to refer
`
`to the same or like parts.
`
`It will be paid attention that detailed description of known arts will
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`be omitted if it is determined that the arts can mislead the embodiments of the invention.
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`In
`
`describing various exemplary embodiments, descriptions of the same or like components will
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`be given in the beginning but omitted in other exemplary embodiments.
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`[0044]
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`Although terms including ordinal numbers such as “first” and “second” may be
`
`used to describe various components, the components are not limited by the terms. The terms
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`are used only to distinguish one component from other components.
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`[0045]
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`As an example of an organic light-emitting display,
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`the implementation of a
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`rollable display will be described below according to an exemplary embodiment. However, a
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`flexible display panel for the rollable display is not limited to this example. For example, a
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`rollable display according to the present invention may be implemented based on displays
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`such as a liquid crystal display (LCD), a field emission display (FED), a plasma display panel
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`(PDP), an organic light-emitting display (OLED), an electrophoresis display (EPD), a
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`quantum dot display (QDD), etc.
`
`[0046]
`
`FIG. 1 is a schematic block diagram of an organic light-emitting display according
`
`to an exemplary embodiment of the present invention. FIG. 2 is a schematic view showing
`
`6
`
`

`

`the circuit configuration of a subpixel of FIG. 1.
`
`FIG. 3 illustrates an example of the
`
`configuration of a subpixel according to an exemplary embodiment of the present invention.
`
`[0047]
`
`As illustrated in FIG.
`
`1, an organic light-emitting display according to an
`
`exemplary embodiment of the present invention comprises an image processor 110, a timing
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`controller 120, a data driver 140, a scan driver 130, and a flexible display panel 150.
`
`[0048]
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`The image processor 110 outputs a data enable signal DE, etc., along with a data
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`signal DATA supplied from the outside.
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`In addition to the data enable signal DE, the image
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`processor 110 may output one or more among a vertical synchronization signal, a horizontal
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`synchronization signal, and a clock signal. But,
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`these signals will not be shown for
`
`convenience of explanation.
`
`[0049]
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`The timing controller 120 receives the data signal DATA, along with the data
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`enable signal DE or driving signals including a vertical synchronization signal, horizontal
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`synchronization signal, and clock signal,
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`from the image processor 110.
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`The timing
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`controller 120 outputs a gate timing control signal GDC for controlling the operation timing
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`of the scan driver 130 and a data timing control signal DDC for controlling the operation
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`timing of the data driver 140, based on a driving signal.
`
`[0050]
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`The data driver 140 samples and latches the data signal DATA supplied from the
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`timing controller 120, in response to the data timing control signal DDC supplied from the
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`timing controller 120, and converts this signal to a gamma reference voltage and outputs it.
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`The data driver 140 outputs the data signal DATA through data lines DLl to DLn. The data
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`driver 140 may be formed in the form of an IC (integrated circuit).
`
`[0051]
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`The scan driver 130 outputs a scan signal while shifting the level of a gate voltage,
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`in response to the gate timing control signal GDC supplied from the timing controller 120.
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`The scan driver 130 outputs a scan signal through scan lines GL1 to GLm. The scan driver
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`

`

`130 is formed in the form of an IC (integrated circuit), or formed on the display panel 150 in
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`the form of a Gate-In-panel.
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`[0052]
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`The flexible display panel 150 displays an image in response to the data signal
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`DATA and scan signal respectively supplied from the data driver 140 and scan driver 130.
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`The flexible display panel 150 comprises subpixels SP that work to display an image.
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`[0053]
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`The subpixels SP may be top-emission type, bottom-emission type, or dual-
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`emission type according to their structure. The subpixels SP may comprise a red subpixel, a
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`green subpixel, and a blue subpixel, or may comprise a white subpixel, a red subpixel, a
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`green subpixel, and a blue subpixel. One or more of the subpixels SP may have a different
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`light-emission area depending on the light-emission characteristics.
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`[0054]
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`As illustrated in FIG. 2, one subpixel comprises a switching transistor SW, a
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`driving transistor DR, a capacitor Cst, a compensation circuit CC, and an organic light-
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`emitting diode OLED.
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`[0055]
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`The switching transistor SW is switched on to store a data signal supplied through
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`the first data line DLl as a data voltage in the capacitor Cst, in response to a scan signal
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`supplied through the first scan line GL1. The driving transistor DR works to cause a drive
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`current to flow between a first power supply line EVDD and a second power supply line
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`EVSS according to the data voltage stored in the capacitor Cst. The organic light-emitting
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`diode OLED works to emit light by the drive current formed by the driving transistor DR.
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`[0056]
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`The compensation circuit CC is a circuit that is added within the subpixel to
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`compensate a threshold voltage, etc. The compensation circuit CC is made up of one or more
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`transistors. The configuration of the compensation circuit CC varies widely with the method
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`of compensation, an example of which will be described below.
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`[0057]
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`As illustrated in FIG. 3, the compensation circuit CC comprises a sensing transistor
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`ST and a sensing line VREF. The sensing transistor ST is connected between a source line of
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`8
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`

`

`the driving transistor DR and the anode (hereinafter, sensing node) of the organic light-
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`emitting diode. The sensing transistor ST works to supply a reset voltage (or sensing voltage)
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`passed through the sensing line VREF to the sensing node or to sense the voltage or current at
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`the sensing node.
`
`[0058]
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`The switching transistor SW has a first electrode connected to the first data line
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`DLl and a second electrode connected to a gate electrode of the driving transistor DR. The
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`driving transistor DR has a first electrode connected to the first power supply line EVDD and
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`a second electrode connected to the anode of the organic light-emitting diode OLED. The
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`capacitor Cst has a first electrode connected to the gate electrode of the driving transistor DR
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`and a second electrode connected to the anode of the organic light-emitting diode. The
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`organic light-emitting diode OLED has the anode connected to the second electrode and a
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`cathode connected to the second power supply line EVSS. The sensing transistor ST has a
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`first electrode connected to the sensing line VREF and a second electrode connected to the
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`anode, which is a sensing node, of the organic light-emitting diode OLED. For reference, the
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`first and second electrodes are defined as source and drain electrodes or drain and source
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`electrodes depending on the transistor type.
`
`[0059]
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`The operating time of the sensing transistor ST may be similar to or the same as or
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`different from that of the switching transistor SW depending on the compensation algorithm
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`(or the configuration of the compensation circuit).
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`In an example, the switching transistor
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`SW may have a gate electrode connected to a la-th scan line GLla, and the sensing transistor
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`ST may have a gate electrode connected to a lb-th scan line Gle. In another example, the
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`la-th scan line GLla connected to the gate electrode of the switching transistor SW and the
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`lb-th scan line Gle connected to the gate electrode of the sensing transistor ST may be
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`connected so that they can be commonly shared.
`
`

`

`[0060]
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`The sensing line VREF may be connected to the data driver.
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`In this case, the data
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`driver may sense the sensing node of the subpixel and perform compensation according to the
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`sensing result, in real time during a non-display period of an image or an N frame period (N
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`is an integer equal to or greater than 1). Meanwhile, the switching transistor SW and the
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`sensing transistor ST may be turned on at the same time.
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`In this case, a sensing operation
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`through the sensing line VREF and a data output operation for outputting a data signal are
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`distinguished based on the time-division method of the data driver.
`
`[0061]
`
`A digital data signal, an analog data signal, or a gamma voltage may be
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`compensated according to a sensing result. Also, a compensation circuit that generates a
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`compensation signal
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`(or compensation voltage) based on the sensing result may be
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`implemented within the data driver, within the timing controller, or as a separate circuit.
`
`[0062]
`
`FIG. 3 illustrates, by way of example, a subpixel with a three-capacitor one-
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`capacitor 3T1C structure which comprises a switching transistor SW, a driving transistor DR,
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`a capacitor Cst, an organic light-emitting diode OLED, and a sensing transistor. Besides, the
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`subpixel may consist of 3T2C, 4T2C, 5T1C, 6T2C, etc., with the addition of a compensation
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`circuit CC.
`
`[0063]
`
`Organic light-emitting displays require no backlight unit, so the flexible display
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`panel may be made thinner, compared to liquid crystal displays. Moreover, since the organic
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`light-emitting display offers flexibility because of its thinness, the flexible display panel can
`
`be bent or curved and the shape of the flexible display panel can be changed by rolling and
`
`unrolling it like a scroll. For this reason, more and more attempts are being made to design
`
`the flexible display panel of the organic light-emitting display and a machine structure for
`
`holding it in various shapes.
`
`[0064]
`
`Now, the structure of a flexible display panel that can be rolled and unrolled like a
`
`scroll to realize a rollable display panel will be described.
`
`10
`
`

`

`[0065]
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`FIG. 4 illustrates the top plane of a flexible display panel according to an
`
`exemplary embodiment of the present invention. FIG. 5 illustrates a cross-section of the
`
`flexible display panel according to the exemplary embodiment of the present invention.
`
`FIGS. 6A and 6B are cross-sectional views showing an example of etching a first substrate.
`
`FIG. 7 is a cross-sectional view showing an example of joining the first substrate and a
`
`second substrate together.
`
`FIG. 8 is a top plan view showing a flexible display panel
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`implemented as a module.
`
`[0066]
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`As illustrated in FIGS. 4 through 8, the flexible display panel 150 according to the
`
`exemplary embodiment of the present
`
`invention comprises a first substrate GLS, an
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`intermediate layer IL having a display area AA. The display area AA includes a plurality of
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`pixels P, and a second substrate MS.
`
`[0067]
`
`The intermediate layer IL has an adhesion layer ADL, along with the pixels P
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`constituting the display area AA. The pixels P may be made up of subpixels that emit light of
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`red (R), white (W), blue (B), and green (G), but are not limited to them. The adhesion layer
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`ADL is made of an adhesive material that facilitates the joining of the first substrate GLS and
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`the second substrate MS and seals the intermediate layer IL located between the first
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`substrate GLS and the second substrate MS.
`
`[0068]
`
`The first substrate GLS is made of glass or resin. The first substrate GLS may have
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`a thickness of 0.01 mm to 0.2 mm. A test result showed that, if the first substrate GLS is thin
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`with a thickness of 0.01 mm to 0.1 mm, this makes it very easy to change the shape by rolling
`
`and unrolling it like a scroll.
`
`[0069]
`
`The first substrate GLS has an etched region (or first thickness portion) GLSl and
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`an unetched region (or second thickness portion) GLS2. The unetched region GLS2 is
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`formed where a pad portion for connecting to an external substrate is provided. The unetched
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`region GLS2 is in the shape of a rectangle which is horizontally long. The unetched region
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`11
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`

`

`GLS2 is provided to increase the rigidity of the area connected to the external substrate. Due
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`to the shape of GLS2, the unetched region GLS2 may take up only 1 to 2 % of the entire area
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`of the first substrate GLS. Also, the thickness t2 of the unetched region GLS2 may range
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`from 0.5 mm to 0.7 mm.
`
`[0070]
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`The rest of the first substrate GLS, except for the unetched region GLS2,
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`is all
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`removed by an etching process, etc., and becomes the etched region GLS1. The etched
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`region GLS1 is provided to mitigate the tensile stress that the first substrate GLS may be
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`subjected to when the flexible display panel 150 is rolled and unrolled like a scroll. Hence,
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`the thickness t1 of the etched region GLS1 may range from 0.01 mm to 0.1 mm.
`
`[0071]
`
`The second substrate MS is made of metal. The thickness of the second substrate
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`MS may range from 0.01 mm to 0.2 mm. The second substrate MS serves to absorb,
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`distribute, and mitigate the tensile stress that the first substrate GLS may be subjected to
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`when the flexible display panel 150 is rolled or unrolled like a scroll. A test result showed
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`that, if the first substrate GLS is thin with a thickness of 0.01 mm to 0.2 m, it is possible to
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`efficiently absorb, distribute, and mitigate the tensile stress that the first substrate GLS may
`
`be subjected to when the flexible display panel 150 is rolled or unrolled like a scroll.
`
`[0072]
`
`The second substrate MS has better resistance to impacts compared to the first
`
`substrate GLS since it is made of metal. Hence, the second substrate MS may be made larger
`
`than the first substrate GLS. That is,
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`the second substrate MS may have at least one
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`protruding part GP that protrudes outwards further than the first substrate GLS1 as illustrated
`
`in FIG. 7. The protruding part GP of the second substrate MS may serve to efficiently protect
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`fragile parts like the comers from impacts the first substrate GLS may be subjected to.
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`[0073] Meanwhile, the flexible display panel 150 is electrically connected and attached to
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`the timing controller 120, data driver 140, scan driver 130, etc. (the image processor, a power
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`supply part, etc. are not shown), and implemented as a module as shown in FIG. 8.
`
`12
`
`

`

`[0074]
`
`The scan driver 130 may be formed on the flexible display panel 150 by Gate In
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`Panel (GIP) technology. That is, the scan driver 130 may be formed on the flexible display
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`panel 150 may be formed by GIP technology on the left side, right side, or both the left and
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`right sides of the display area AA so that the flexible display panel 150 can be rolled like a
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`scroll. However, the present invention is not limited to this.
`
`[0075]
`
`A data printed circuit board (hereinafter, “data PCB”) 135 is electrically connected
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`to the flexible display panel 150 through a first connecting member 145. The first connecting
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`member 145 may be, but not limited to, a Chip On Film (COF) with the data driver 140
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`mounted on it. For example, the first connecting member 145 may be implemented by Tape
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`Carrier Package (TCP) technology and electrically connect the data PCB 135 and the flexible
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`display panel 150. To prevent or reduce the likelihood that the data PCB 135 is damaged due
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`to repeated stress due to rolling and unrolling, it is advantageous to place the data PCB 135 at
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`an end of the flexible display panel 150 further away from the roller 160.
`
`[0076]
`
`The data PCB 135 is connected to a control board 125 through a second connecting
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`member 127. A plurality of second connecting members 127 may be provided. The timing
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`controller 120, etc. is mounted on the control board 125. The second connecting member 127
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`may be, but not limited to, a Flexible Flat Cable (FFC). The control board 125 may be
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`connected to the image processor 110, the power supply part, etc. by a connecting cable to
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`transmit signals and power for displaying images on the flat display panel 150.
`
`[0077]
`
`The structure of a mechanical structure for realizing a rollable display will now be
`
`described.
`
`[0078]
`
`FIGS. 9A and 9B are views showing a rollable display according to an exemplary
`
`embodiment of the present invention. FIG. 10 is a perspective view showing a flexible
`
`display panel and a roller.
`
`13
`
`

`

`[0079]
`
`As illustrated in FIGS. 9A through 10,
`
`the rollable display according to the
`
`exemplary embodiment of the present invention comprises a flexible display panel 150
`
`implemented as a module (hereinafter, abbreviated as “flexible display panel”), a roller 160,
`
`and a retractable portion 170.
`
`[0080]
`
`The roller 160 provides a mechanical structure that allows the flexible display panel
`
`150 to be rolled up around its circumference surface and unrolled from it. The roller 160 is
`
`accommodated in the retractable portion 170.
`
`[0081]
`
`The retractable portion 170 can accommodate the flexible display panel 150 and the
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`roller 160. A driving device, such as a motor, a gear, a power source, etc. for electrically
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`rotating the roller 160 may be included within the retractable portion 170. As such, the
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`retractable portion 170 may be designed to be circular, elliptical, rectangular, or polygonal in
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`shape according to the configuration or design of the driving device.
`
`[0082]
`
`The flexible display panel 150 comes out of the retractable portion 170 or goes into
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`the retractable portion 170 depending on the direction of rotation of the driving device. For
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`example, when the driving device rotates in the rl direction, the roller 160 allows the flexible
`
`display panel 150 to be unrolled.
`
`In this case, the flexible display panel 150 moves in the y2
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`direction, coming out of the retractable portion 170. By contrast, when the driving device
`
`rotates in the r2 direction, the roller 160 allows the flexible display panel 150 to be rolled.
`
`In
`
`this case,
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`the flexible display panel 150 moves in the yl direction and goes into the
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`retractable portion 170.
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`[0083]
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`The structure of the rollable display will be described below with reference to FIGS.
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`11 and 12. FIGS. 11A through 12 are views for explaining the basic structure of the rollable
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`display panel.
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`14
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`

`

`[0084]
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`Referring to FIGS. 11A through 12, the rollable display according to the present
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`invention comprises a roller 160, a control board 125, a flexible display panel 150, and a data
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`PCB 135.
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`[0085]
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`The roller 160 may be approximately cylindrical. That is, a cross-section of the
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`panel roller 150 may be circular. However, the roller 150 is not limited to this shape, but
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`may take any shape as long as the flexible display panel 150 can be rolled up with ease. The
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`roller 160 rotates about an axis 131 that extends in a longitudinal direction of the roller (in the
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`direction of x axis).
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`[0086]
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`The roller 160 may have an internal space for accommodating the control board
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`125. The internal space may further have a stationary structure for fixing the control board
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`125. The stationary structure may be provided on the inside of the roller 160 and fix the
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`control board 125 to prevent the control board 125 from falling out and colliding with other
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`structures. This means that the movement of the control board 125 may be restrained and
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`restricted within the roller 160.
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`[0087] The rollable display according to the present invention can improve space utilization
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`since the control board 125 is embedded in the roller 160 and give the user aesthetic pleasure
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`since the control board 125 is not visible from the outside.
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`[0088]
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`The roller 160 further comprises a slit 161 that opens to the internal space
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`accommodating the control board 125. That is, the slit 161 is an open part of the roller 160,
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`and functions as a path connecting the control board 125 accommodated in the roller 160 to
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`external structures like the data PCB 135.
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`[0089]
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`The flexible display panel 150 comprises a display area where an input image is
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`displayed. The user may recognize information output from the flexible display panel 150
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`through the display area. The front side of the flexible display panel 150 is one side of the
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`flexible display panel 150 where the display area is defined. By contrast, the rear side of the
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`15
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`

`

`flexible display panel 150 is the side opposite to the front side of the flexible display panel,
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`where the display area is not visible to the user.
`
`[0090]
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`The flexible display panel 150 may be rolled up around the roller 160. That is, the
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`rollable display according to the present invention allows the flexible display panel 150 to be
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`repeatedly rolled around or unrolled from the circumference of the roller 160 easily.
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`[0091]
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`The flexible display panel 150 may be rolled around or unrolled from the roller 160
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`and maintain a first state or second state. The first state may refer to the state in which the
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`flexible display panel 150 is rolled around the roller 160. In the first state, the display area on
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`the flexible display panel 150 is not exposed to the outside so that the display area is not
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`visible to the user.
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`In the first state, the display area of the flexible display panel 150 and the
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`outside surface of the roller 160 may be opposite each other.
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`In the first state, the display
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`device may be turned off so that no input image is displayed.
`
`[0092]
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`The second state may refer to the unrolled state of the flexible display panel 150.
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`In the second state, the flexible display panel 150 may remain approximately flat.
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`In the
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`second state, the display area on the flexible display panel 150 is visible to the user. In the
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`second state, the display device may be turned on so that an input image is displayed.
`
`[0093]
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`If required, the flexible display panel 150 may change from the first state to the
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`second state or from the second state to the first state. Changes in the state of the flexible
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`display panel 150 may be caused by physical external forces provided directly by the user.
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`The changes in the state of the flexible display panel 150 may be controlled by a control part,
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`in response to a predetermined signal. The rolling up of the flexible display panel 150 may
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`be controlled by a selected driving device, driving circuit, etc.
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`[0094]
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`One end of the flexible display panel 150 is fixed to the roller 160. To fix them, a
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`bonding member or fixing member may be further provided between one end of the flexible
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`display panel 150 and the roller 160.
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`16
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`

`

`[0095] In another embodiment, the flexible display panel 150 is connected to an auxiliary
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`sheet 190 that is secured to the roller 160 at location 176 next to or near slit 161. That is, the
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`flexible panel 150 is not directly connected to the roller 160 but is connected Via the auxiliary
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`sheet 190 to the roller 160. The auxiliary sheet 190 is a flexible sheet with a higher strength
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`and durability than the flexible panel 150. When the flexible panel 150 is fully unrolled from
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`the roller 160, the flexible panel 150 does not contact the circumference surface of the roller
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`160 and the flexible panel 150 hangs from the roller 160 Via the auxiliary sheet 190. The
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`auxiliary sheet 190 can have enough rigidity so that the end portion of the flexible display
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`panel 150 connected to the auxiliary sheet 190 is bent with a larger radius of curvature onto
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`the roller 160 (with a slight gap between the edge of the flexible panel 150 and the roller 160)
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`to mitigate the mechanical stress at the edge of the flexible display panel 150 when the
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`flexible display panel 150 is rolled around the roller 160.
`
`[0096]
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`The unetched region GLSZ is located on the other end of the flexible display panel
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`150 which is not bonded to the roller 160. The unetched region GLSZ protrudes outwards
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`further than the etch