Patent Description:
With the development of the information society, there have been growing demands for various types of display devices, and in order to meet these demands, research has been conducted thereon and various display devices have been used recently, including a liquid crystal display (LCD), a plasma display panel (PDP), an electroluminescent display (ELD), a vacuum fluorescent display (VFD), and the like.

Among them, a display device using an organic light emitting diode (OLED) has excellent luminance and viewing angle characteristics in comparison with a liquid crystal display device, and requires no backlight unit, such that the OLED display device can be implemented as an ultrathin display device.

In addition, a flexible display panel may be bent or rolled on a roller. By using the flexible display panel, a display device rolled or unrolled on the roller may be implemented. Many studies are conducted on the structure of rolling or unrolling the flexible display on the roller.

<CIT> Al relates to a projection screen, and more particularly to a cabinet projection screen with an automatic cover-lifting function.

It is an object of the present disclosure to solve the above and other problems. It is another object of the present disclosure to provide a display device having shafts for providing power for opening and closing a door of the display device. It is yet another object of the present disclosure to provide a display device capable of reducing noise and vibration produced during driving of the door of the display device.

According to an aspect of the present disclosure in order to achieve the above objects, there is provided a display device including: a flexible display panel; a roller on which the display panel is rolled or unrolled; a housing having an opening through which the display panel passes, and providing an internal accommodation space, the roller rotatably mounted in the internal accommodation space; and a door assembly mounted in the internal accommodation space at a position adjacent to the opening of the housing, and opening and closing the opening, wherein the door assembly includes: a door for opening and closing the opening; a motor for providing power to the door; a first shaft gear disposed between the motor and the door, and transmitting the power, provided by the motor, to the door; a first shaft having a first end connected to the first shaft gear, and rotating together with the first shaft gear; a joint connected to a second end of the first shaft; a second shaft having a first end connected to the joint, and rotating together with the first shaft; and a second shaft gear connected to a second end of the second shaft, and transmitting power to the door.

The display device according to the present disclosure has the following effects.

According to at least one of embodiments of the present disclosure, shafts for providing power for opening and closing a door of a display device may be provided.

According to at least one of embodiments of the present disclosure, noise and vibration produced during driving of the door of the display device may be reduced.

However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the present disclosure, are given by illustration only, since various changes and modifications within the scope of the present disclosure will become apparent to those skilled in the art from this detailed description.

<FIG> are diagrams illustrating examples of a display device according to embodiments of the present disclosure.

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings, in which the same or similar elements are designated by the same reference numerals, and a redundant description thereof will be omitted.

The terms "module" and "unit" for elements used in the following description are given simply in view of the ease of the description, and do not have a distinguishing meaning or role.

In addition, it will be noted that a detailed description of known arts will be omitted if it is determined that the detailed description of the known arts can obscure the embodiments of the present disclosure. Further, the accompanying drawings are used to help easily understand various technical features and it should be understood that the embodiments presented herein are not limited by the accompanying drawings, and the present disclosure should be construed to extend to any alterations, equivalents and substitutes in addition to those which are particularly set out in the accompanying drawings.

As used herein, the singular forms are intended to include the plural forms as well, unless the context clearly indicates otherwise.

In the following description, even if an embodiment is described with reference to a specific figure, if necessary, reference numeral not shown in the specific figure may be referred to, and reference numeral not shown in the specific figure is used when the reference numeral is shown in the other figures.

Referring to <FIG>, a display device <NUM> may include a display unit <NUM> and a housing <NUM>. The housing <NUM> may have an internal space. At least a portion of the display unit <NUM> may be located inside the housing <NUM>. At least a portion of the display unit <NUM> may be located outside of the housing <NUM>. The display unit <NUM> may display an image.

A direction parallel to a longitudinal direction of the housing <NUM> may be referred to as a first direction DR1, a positive x-axis direction, a negative x-axis direction, a left direction, or a right direction. A direction in which the display unit <NUM> displays an image may be referred to as a positive z-axis direction, a forward direction or the front. A direction opposite to the direction in which the display unit <NUM> displays the image may be referred to as a negative z-axis direction, a rearward direction or the rear. A third direction DR3 may be parallel to the positive z-axis direction or the negative z-axis direction. A direction parallel to a height direction of the display device <NUM> may be referred to as a second direction DR2, a positive y-axis direction, a negative y-axis direction, an upward direction, or a downward direction.

The third direction DR3 may be a direction perpendicular to the first direction DR1 and/or the second direction DR2. The first direction DR1 and the second direction DR2 may be collectively referred to as a horizontal direction. Also, the third direction DR3 may be referred to as a vertical direction. A left-right direction LR may be parallel to the first direction DR1, and an up-down direction UD may be parallel to the second direction DR2.

Referring to <FIG>, the entire display unit <NUM> may be located inside the housing <NUM>. At least a portion of the display unit <NUM> may be located outside of the housing <NUM>. A degree of exposure of the display unit <NUM> to the outside of housing <NUM> may be adjusted as needed.

Referring to <FIG>, the display unit <NUM> may include a display panel <NUM> and a plate <NUM>. The display panel <NUM> may be flexible. For example, the display panel <NUM> may be an Organic Light Emitting Display (OLED).

The display panel <NUM> may have a front surface for displaying an image. The display panel <NUM> may have a rear surface disposed opposite the front surface. The front surface of the display panel <NUM> may be covered with a light-transmissive material. For example, the light-transmissive material may be a synthetic resin or plastic.

The plate <NUM> may be coupled, fastened, or attached to the rear surface of the display panel <NUM>. The plate <NUM> may include a metal material. The plate <NUM> may be referred to as a module cover <NUM>, a cover <NUM>, a display panel cover <NUM>, a panel cover <NUM>, and an apron <NUM>.

Referring to <FIG>, the plate <NUM> may include a plurality of segments 15c. A magnet <NUM> may be disposed in a recess <NUM> of the segment 15c. The recess <NUM> may be formed in a surface facing the display panel <NUM> of the segment 15c. The recess <NUM> may be formed in a front surface of each segment 15c. The magnet <NUM> is received in the recess <NUM>, such that the magnet <NUM> may be prevented from being exposed to the outside of the segment 15c. Even when being in contact with the segments 15c, the display panel <NUM> may be flat without being creased.

Referring to <FIG>, a plurality of magnets <NUM> may be disposed on a link <NUM>. For example, at least one magnet <NUM> may be disposed on a first arm 73a, and at least one magnet <NUM> may be disposed on a second arm 73b. The plurality of magnets <NUM> may be spaced apart from each other.

Referring to <FIG>, one magnet <NUM> may be disposed on the first arm 73a and the second arm 73b, respectively. The magnet <NUM> may have a shape which is elongated toward a long side of the first arm 73a and the second arm 73b. As the magnet <NUM> has a shape which is elongated toward the long side of the first arm 73a and the second arm 73b, an area of a portion of the link <NUM> that comes into close contact with the display panel and the module cover may increase. Accordingly, adhesion force between the link <NUM>, the display panel, and the module cover may be enhanced.

Referring to <FIG>, the magnet <NUM> may be disposed in a recessed portion <NUM> formed in the link <NUM>. The recessed portion <NUM> may have a shape which is recessed inwardly of the link <NUM>. The magnet <NUM> may be coupled to the link <NUM> by at least one screw <NUM>.

A width LHW of the recessed portion <NUM> which is recessed inwardly of the link <NUM> may be equal to or greater than a thickness MGW of the magnet <NUM>. If the thickness MGW of the magnet <NUM> is greater than the width LHW of the recessed portion <NUM>, the display panel <NUM> and the module cover <NUM> may not come into close contact with the link <NUM>. In this case, the display panel <NUM> may be creased or may not be flat.

A panel protection part <NUM> may be disposed on a rear surface of the display panel <NUM>. The panel protection part <NUM> may protect the display panel <NUM> from damage due to friction between the display panel <NUM> and the module cover <NUM>. The panel protection part <NUM> may include a metal material. The panel protection part <NUM> may be ultra-thin. For example, the panel protection part <NUM> may have a thickness of about <NUM>.

As the panel protection part <NUM> includes a metal material, an attraction force may be generated between the panel protection part <NUM> and the magnet <NUM>. Accordingly, even when the module cover <NUM>, disposed between the panel protection part <NUM> and the link <NUM>, does not include a metal material, the module cover <NUM> may come into close contact with the magnet <NUM>.

Referring to <FIG>, the module cover <NUM> may come into close contact with the link <NUM> by an upper bar <NUM> disposed at an upper side, and a guide bar <NUM> (see <FIG>) disposed at a lower side. In the link <NUM>, a portion between the upper bar <NUM> and the guide bar <NUM> may not come into close contact with the module cover <NUM>. Alternatively, a center portion of the link <NUM> may not come into close contact with the module cover <NUM>. The center portion of the link <NUM> may be in the vicinity of an arm joint <NUM>. In this case, distances APRD1 and APRD2 between the module cover <NUM> and the link <NUM> may not be kept constant. In this case, the display panel <NUM> may be curved or bent.

Referring to <FIG>, in the case where the magnet <NUM> is disposed in the recessed portion <NUM> of the link <NUM>, the magnet <NUM> attracts the panel protection part <NUM>, such that the module cover <NUM> may also come into close contact with the magnet <NUM>. That is, the center portion of the link <NUM> may come into close contact with the module cover <NUM>.

Referring to <FIG>, a bead <NUM> may be formed on an upper surface of a segment 15b. The bead <NUM> may have a shape which is recessed inwardly of the segment 15b. The bead <NUM> may have a shape which is recessed in the negative y-axis direction. For example, the bead <NUM> may be formed by pressing the segment 15b. A plurality of beads <NUM> may be formed on the segment 15b. The plurality of beads <NUM> may be spaced apart from each other. The bead <NUM> may improve rigidity of the segment 15b. The bead <NUM> may prevent the segment 15b from being deformed due to external impact. The segment 15b may be fixed to a rear side of the display panel <NUM> by an adhesive member <NUM>. The panel protection part <NUM> (see <FIG>) may be disposed between the adhesive member <NUM> and the display panel <NUM>. For example, the adhesive member <NUM> may be a double-sided tape.

Referring to <FIG>, a source PCB <NUM> may be disposed over the module cover <NUM>. During rolling up or rolling down, the source PCB <NUM> may be changed in position in accordance with the movement of the module cover <NUM>. An FFC cable <NUM> may be disposed at the center of the module cover <NUM> in the first direction. The FFC cable <NUM> may also be disposed at both ends of the module cover <NUM> in the first direction.

Referring to <FIG>, a segment 15d may include a recessed portion <NUM> which is recessed in the negative z-axis direction. The recessed portion <NUM> may form
a space between the display panel <NUM> and the module cover <NUM>. The FFC cable <NUM> may be accommodated in the space formed by the recessed portion <NUM>. In addition, the recessed portion <NUM> may improve rigidity of the segment 15d.

The bead <NUM> may be disposed on the segment 15d, except for a portion where the recessed portion <NUM> is formed. At the portion where the recessed portion <NUM> is formed, the thickness of the segment 15d decreases in the third direction, such that the bead <NUM> may not be disposed at the portion.

Referring to <FIG>, a segment 15e may have a pass-through portion <NUM> formed at the center thereof in the first direction. The pass-through portion <NUM> may pass through the center of the segment 15e in the second direction. That is, the pass-through portion <NUM> may be a hole formed in the segment 15e. The pass-through portion <NUM> may be a portion where the FFC cable <NUM> is disposed. The pass-through portion <NUM> is formed in the segment 15e, such that a thickness of the segment 15e may be reduced, compared to the case where the FFC cable <NUM> is disposed in the recessed portion <NUM>.

The bead <NUM> may be disposed on the segment 15e, except for a portion where the pass-through portion <NUM> is disposed. At the portion where the pass-through portion <NUM> is disposed, the thickness of the segment 15e decreases in the third direction, such that the bead <NUM> may not be disposed at the portion.

Referring to <FIG>, a top case <NUM> may cover the source PCB <NUM> and the upper bar <NUM>, in addition to the display panel <NUM> and the module cover <NUM>. The upper bar <NUM> has one surface coupled to a rear surface of the module cover <NUM>, and the other surface coupled to the source PCB <NUM>. The upper bar <NUM> may be fixed to the module cover <NUM> to support the source PCB <NUM>.

A lower end of the FFC cable <NUM> may be connected to a timing controller board <NUM> (see <FIG>) in a panel roller <NUM> (see <FIG>). The FFC cable <NUM> may be wound around or unwound from the panel roller <NUM> along with the display unit <NUM>.

A portion of the FFC cable <NUM> may be disposed between the display panel <NUM> and the module cover <NUM>. The portion of the FFC cable <NUM>, which is disposed between the display panel <NUM> and the module cover <NUM>, may be referred to as a first portion 231a. The first portion 231a may be disposed in the recessed portion <NUM> of the segment 15d. Alternatively, the first portion 231a may be received in the recessed portion <NUM> of the plurality of segments 15d.

A portion of the FFC cable <NUM> may pass through a segment 15f. The portion of the FFC cable <NUM>, which passes through the segment 15f, may be referred to as a second portion 231b. The segment 15f may include a first hole 521a formed in a front surface, and a second hole 521b formed in a rear surface. The first hole 521a and the second hole 521b may be connected to each other to form one hole <NUM>. The hole <NUM> may pass through the segment 15f in the third direction. The second portion 231b may pass through the hole <NUM>. The hole <NUM> may be referred to as a connection hole <NUM>.

An upper end of the FFC cable <NUM> may be electrically connected to the source PCB <NUM>. A portion of the FFC cable <NUM> may be disposed on the rear surface of the module cover <NUM>. The portion of the FFC cable <NUM>, which is disposed on the rear surface of the module cover <NUM>, may be referred to as a third portion 231c. The third portion 231c may be electrically connected to the source PCB <NUM>.

The third portion 231c may be covered by the top case <NUM>. Accordingly, the third cover 231c may be prevented from being exposed to the outside.

Referring to <FIG>, the FFC cable <NUM> may be connected to the timing controller board <NUM> mounted in the panel roller <NUM>. A through-hole <NUM> may be formed in the panel roller <NUM>, and the FFC cable <NUM> may pass through the through-hole <NUM> to be connected to the timing controller board <NUM>.

The through-hole <NUM>, formed at a first side of the panel roller <NUM>, may pass through an outer circumference of the panel roller <NUM>. The FFC cable <NUM> may pass through the through-hole <NUM> to be connected to a first side of the timing controller board <NUM>.

Even when the FFC cable <NUM> is disposed on the outer circumference of the panel roller <NUM>, the through-hole <NUM> may allow the the FFC cable <NUM> to remain connected to the timing controller board <NUM>. Accordingly, the FFC cable <NUM> may be rotated together with the panel roller <NUM> without being twisted.

A portion of the FFC cable <NUM> may be wound around the panel roller <NUM>. The portion of the FFC cable <NUM>, which is wound around the panel roller <NUM>, may be referred to as a fourth portion 231d. The fourth portion 231d may come into contact with an outer circumferential surface of the panel roller <NUM>.

A portion of the FFC cable <NUM> may pass through the through-hole <NUM>. The portion of the FFC cable <NUM>, which passes through the through-hole <NUM>, may be referred to as a fifth portion 231e.

A lower end of the FFC cable <NUM> may be electrically connected to the timing controller board <NUM>. A portion of the FFC cable <NUM> may be disposed inside the panel roller <NUM>. The portion of the FFC cable <NUM>, which is disposed inside the panel roller <NUM>, may be referred to as a sixth portion 231f. The sixth portion 231f may be electrically connected to the timing controller board <NUM>.

Referring to <FIG>, a lower end of the display panel <NUM> may be connected to the roller <NUM>. The display panel <NUM> may be rolled on or unrolled from the roller <NUM>. A front surface of the display panel <NUM> may be coupled to the plurality of source PCBs <NUM>. The plurality of source PCBs <NUM> may be spaced apart from each other.

A source chip-on film (COF) <NUM> may connect the display panel <NUM> and the source PCBs <NUM>. The source COF <NUM> may be located on the front surface of the display panel <NUM>. The roller <NUM> may include a first part <NUM> and a second part <NUM>. The first part <NUM> and the second part <NUM> may be fastened by a screw. The timing controller board <NUM> may be mounted in the roller <NUM>.

The source PCBs <NUM> may be electrically connected to the timing controller board <NUM>. The timing controller board <NUM> may transmit digital video data and a timing control signal to the source PCBs <NUM>.

A cable <NUM> may electrically connect the source PCBs <NUM> and the timing controller board <NUM>. For example, the cable <NUM> may be a flexible flat cable (FFC). The cable <NUM> may pass through a hole 331a. The hole 331a may be formed in a seating part <NUM> or the first part <NUM>. The cable <NUM> may be disposed between the display panel <NUM> and the second part <NUM>.

The seating part <NUM> may be formed on an outer circumference of the first part <NUM>. The seating part <NUM> may be formed on a stepped portion of the outer circumference of the first part <NUM>. The seating part <NUM> may form a space B. When the display unit <NUM> is rolled on the roller <NUM>, the source PCBs <NUM> may be accommodated in the seating part <NUM>. As the source PCBs <NUM> are accommodated in the seating part <NUM>, the source PCBs <NUM> may not be twisted or bent, and durability may be improved.

The cable <NUM> may electrically connect the timing controller board <NUM> and the source PCBs <NUM>.

Referring to <FIG>, the roller <NUM>, around which the display unit <NUM> is rolled, may be mounted on the first base <NUM>. The first base <NUM> may be a base of the housing <NUM>. The roller <NUM> may be elongated in the longitudinal direction of the housing <NUM>. The first base <NUM> may be connected to a side surface 30a of the housing <NUM>.

Referring to <FIG> and <FIG>, beams 31a may be formed at the first base <NUM>. The beams 31a may improve bending or torsional rigidity of the first base <NUM>. Many components may be mounted on the first base <NUM>, such that the first base <NUM> may be under a heavy load. As the rigidity of the first base <NUM> is improved, sagging of the first base <NUM> due to the load may be prevented. For example, the beams 31a may be formed by a press process.

A second base <NUM> may be spaced upwardly from the first base <NUM>. A space S1 may be formed between the first base <NUM> and the second base <NUM>. The roller <NUM>, around which the display unit <NUM> is rolled, may be accommodated in the space S1. The roller <NUM> may be disposed between the first base <NUM> and the second base <NUM>.

The second base <NUM> may be connected to the side surface 30a of the housing <NUM>. A bracket <NUM> may be fastened to an upper surface of the first base <NUM>. The bracket <NUM> may be fastened to the side surface 30a of the housing <NUM>.

Beams 32a may be formed at the second base <NUM>. The beams 32a may improve bending or torsional rigidity of the second base <NUM>. The beams 32a may be formed by a press process.

A third part 32d may be connected to the first part 32b and the second part 32c. A fourth part 32e may be connected to the first part 32b and the second part 32c. A space S2 may be formed between the third part 32d and the fourth part 32e. Accordingly, bending or torsional rigidity of the second base <NUM> may be improved. The third part 32d may be referred to as a reinforcing rib 32d or a rib 32d. The fourth part 32e may be referred to as a reinforcing rib 32e or a rib 32e.

Many components may be mounted on the second base <NUM>, such that the second base <NUM> may be under a heavy load. As the rigidity of the second base <NUM> is improved, sagging of the second base <NUM> due to the load may be prevented.

A first reinforcing plate <NUM> may be disposed between the first base <NUM> and the second base <NUM>. The first reinforcing plate <NUM> and the second base <NUM> may be fastened by a screw. The first reinforcing plate <NUM> may support the second base <NUM>. The first reinforcing plate <NUM> may prevent sagging of the second base <NUM>. The first reinforcing plate <NUM> may be disposed at a center portion of the first base <NUM> or at a center portion of the second base <NUM>. The first reinforcing plate <NUM> may have a curved portion 34a. The curved portion 34a may be formed along the roller <NUM>. The curved portion 34a may not come into contact with the roller <NUM> or the display unit <NUM> rolled on the roller <NUM>. The curved portion <NUM> may be maintained at a predetermined distance from the roller <NUM>, so as not to interrupt rotation of the roller <NUM>.

A second reinforcing plate <NUM> may be fastened to the first base <NUM> and the first reinforcing plate <NUM>. The second reinforcing plate <NUM> may support the first reinforcing plate <NUM>. The second reinforcing plate <NUM> may be disposed at the rear of the first reinforcing plate <NUM>. The second reinforcing plate <NUM> may be disposed at the rear of the first base <NUM>. The second reinforcing plate <NUM> may be disposed perpendicular to the first base <NUM>. The second reinforcing plate <NUM> may be fastened to the beams 31a of the first base <NUM>. The second base <NUM> may face the front surface or the rear surface of the housing <NUM>.

Referring to <FIG>, a second base 32f may not form a space. If the second base 32f is not under a heavy load, beams <NUM> of the second base 32f may provide sufficient rigidity to the second base 32f. A first base <NUM>' may include beams 31a'.

Referring to <FIG> and <FIG>, a motor assembly <NUM> may be mounted on the second base <NUM>. The motor assembly <NUM> may have drive shafts formed on both sides thereof. A right drive shaft and a left drive shaft of the motor assembly <NUM> may rotate in the same direction. Alternatively, the right drive shaft and the left drive shaft of the motor assembly <NUM> may rotate in opposite directions.

The motor assembly <NUM> may include a plurality of motors. The plurality of motors may be connected in series to each other. The plurality of motors of the motor assembly <NUM> are connected in series, thereby outputting high torque.

Lead screws <NUM> may be disposed on each of the left side and the right side of the motor assembly <NUM>. The motor assembly <NUM> may be connected to the lead screws <NUM>. Couplings <NUM> may connect the lead screws <NUM> with the drive shafts of the motor assembly <NUM>.

The lead screw <NUM> may have a screw thread formed in a longitudinal direction. A direction of the screw thread formed on the right lead screw <NUM> may be opposite to a direction of the screw thread formed on the left lead screw <NUM>. The direction of the screw thread formed on the right lead screw <NUM> may be the same as the direction of the screw thread formed on the left lead screw <NUM>. A pitch of the left lead screw <NUM> may be the same as a pitch of the right lead screw <NUM>.

Bearings 830a and 830b may be mounted on the second base <NUM>. The bearings 830a and 830b may support both sides of the lead screws <NUM>. The bearings 830a and 830b may include inner bearings 830b disposed close to the motor assembly <NUM>, and outer bearings 830a disposed away from the motor assembly <NUM>. The lead screws <NUM> may be rotated stably by the bearings 830a and 830b.

Slides <NUM> may be engaged with the lead screws <NUM>. The slides <NUM> may be movable in a longitudinal direction of the lead screws <NUM> during rotation of the lead screws <NUM>. The slide <NUM> may move between the outer bearing 830a and the inner bearing 830b. The slides <NUM> may be disposed at the left lead screw <NUM> and the right lead screw <NUM>, respectively. A left slide <NUM> may be engaged with the left lead screw <NUM>. A right slide <NUM> may be engaged with the right lead screw <NUM>.

The left slide <NUM> and the right slide <NUM> may be disposed symmetrically with respect to the motor assembly <NUM>. By driving the motor assembly <NUM>, the left slide <NUM> and the right slide <NUM> may be moved away from or closer to each other by the same distance.

Referring to <FIG>, the motor assembly <NUM> may include a plate <NUM>. The plate <NUM> may be referred to as a mount plate <NUM> or a motor mount plate <NUM>. Coupling portions <NUM> may be formed on an upper surface of the second base <NUM>. The plate <NUM> may be fastened to the coupling portions <NUM> b screws S. The motor assembly <NUM> may be spaced apart from the upper surface of the second base <NUM>. Washers <NUM> may be disposed between the plate <NUM> and the screws S. The washers <NUM> may include a rubber material. The washers <NUM> may reduce vibration occurring in the motor assembly <NUM>. The washers <NUM> may improve driving stability of the display device <NUM>.

Referring to <FIG>, a guide rail <NUM> may be disposed at the second base <NUM>. The guide rail <NUM> may be disposed in parallel to the lead screw <NUM>. The slide <NUM> may be engaged with the guide rail <NUM>. A first stopper 861b may be disposed on a first side of the guide rail <NUM>, and a second stopper 861a may be disposed on a second side of the guide rail <NUM>. The slide <NUM> may move within a limited range between the first stopper 861b and the second stopper 861a.

A spring <NUM> may surround the lead screw <NUM>. The lead screw <NUM> may pass through the spring <NUM>. The spring <NUM> may be disposed between the inner bearing 830b and the slide <NUM>. A first side of the spring <NUM> may come into contact with the inner bearing 830b, and a second side of the spring <NUM> may come into contact with the slide <NUM>. The spring <NUM> may provide elasticity to the slide <NUM>.

When the slide <NUM> is stopped by the first stopper 861b, the spring <NUM> may be compressed to the maximum. When the slide <NUM> is stopped by the first stopper 861b, the spring <NUM> has a minimum length. When the slide <NUM> is stopped by the first stopper 861b, a distance between the slide <NUM> and the inner bearing 830b may be minimum.

Referring to <FIG>, when the slide <NUM> is stopped by a second stopper 861a, the spring <NUM> may be stretched to the maximum. When the slide <NUM> is stopped by the second stopper 861b, the spring <NUM> may have a maximum length. When the slide <NUM> is stopped by the second stopper 861a, a distance between the slide <NUM> and the inner bearing 830b may be maximum.

Referring to <FIG>, the first part 820a may be engaged with the guide rail <NUM>. The first part 820a may move along the guide rail <NUM>. The first part 820a may be restricted from moving in a longitudinal direction of the guide rail <NUM>. The second part 820b may be disposed over the first part 820a. The first part 820a and the second part 820b may be fastened to each other by a screw. The second part 820b may be spaced apart from the guide rail <NUM>. The lead screw <NUM> may pass through the second part 820b. For example, the second part 820b may include a male thread engaged with a female thread. Accordingly, even when the lead screw <NUM> is rotated, the slide <NUM> is stably movable along the guide rail <NUM> without being rotated.

The third part 820c may be coupled to a first side of the second part 820b. The third part 820c may come into contact with the spring <NUM>. The third part 820c may receive elastic force from the spring <NUM>.

Referring to <FIG> and <FIG>, a link mount <NUM> may be mounted on the second base <NUM>. A first side of a second arm <NUM> may be pivotally connected to the link mount <NUM>. A second side of the second arm <NUM> may be pivotally connected to a joint <NUM>. The second side of the second arm <NUM> may be pivotally connected to a second shaft 913b. A first side of a rod <NUM> may be pivotally connected to the slide <NUM>. A second side of the rod <NUM> may be pivotally connected to the second arm <NUM> or a third arm <NUM>. A first side of the third arm <NUM> may be pivotally connected to the link mount <NUM>. A second side of the third arm <NUM> may be pivotally connected to the second side of the rod <NUM>. The link mount <NUM> may include a shaft <NUM>. The second arm <NUM> or the third arm <NUM> may be pivotally connected to the shaft <NUM>.

A link bracket <NUM> may be referred to as a link cap <NUM>. The link bracket <NUM> may be coupled to a top case <NUM>. The top case <NUM> may be referred to as a case top <NUM>, an upper bar <NUM>, a top <NUM>, or a bar <NUM>. The top case <NUM> may be disposed at an upper end of the display unit <NUM>. The display unit <NUM> may be fixed to the top case <NUM>.

A first side of a first arm <NUM> may be pivotally connected to the joint <NUM>. The first side of the first arm <NUM> may be pivotally connected to a first shaft 913a. A second side of the first arm <NUM> may be pivotally connected to the link bracket <NUM> or the top case <NUM>.

A gear g1 may be formed on the first side of the first arm <NUM>. A gear g2 may be formed on the second side of the second arm <NUM>. The gear g1 of the first arm <NUM> and the gear g2 of the second arm <NUM> may be engaged with each other.

When the slide <NUM> moves closer to the outer bearing 830a, the second arm <NUM> or the third arm <NUM> may be raised. In this case, a direction in which the second arm <NUM> or the third arm <NUM> is raised may be referred to as a raised direction DRS.

The second arm <NUM> may include a protrusion <NUM> protruding in the raised direction DRS. The protrusion <NUM> may be referred to as a connection part <NUM>. The third arm <NUM> may include a protrusion <NUM> protruding in the raised direction DRS. The protrusion <NUM> may be referred to as a connection part <NUM>. The protrusion <NUM> of the second arm <NUM> and the protrusion <NUM> of the third arm <NUM> may face or come into contact with each other. The second side of the rod <NUM> may be fastened to the protrusion <NUM> of the second arm <NUM> or the protrusion <NUM> of the third arm <NUM>.

A link <NUM> may include the first arm <NUM>, the second arm <NUM>, the third arm <NUM>, and/or the joint <NUM>.

Referring to <FIG> and <FIG>, an angle formed between the second arm <NUM> or the third arm <NUM> and the second base <NUM> may be referred to as theta S. When the rod <NUM> is connected to an upper side of the second part 820b, an angle formed between the rod <NUM> and the second base <NUM> may be referred to as theta A, and a minimum force required for the rod <NUM> to raise the second arm <NUM> or the third arm <NUM> may be referred to as Fa. When the rod <NUM> is connected to the middle of the second part 820b, an angle formed between the rod <NUM> and the second base <NUM> may be referred to as theta B, and a minimum force required for the rod <NUM> to raise the second arm <NUM> or the third arm <NUM> may be referred to as Fb. When the rod <NUM> is connected to a lower side of the second part 820b, an angle formed between the rod <NUM> and the second base <NUM> may be referred to as theta C, and a minimum force required for the rod <NUM> to raise the second arm <NUM> or the third arm <NUM> may be referred to as Fc.

If theta S is the same, a relationship of theta A < theta B < theta C may be formed. Further, if theta S is the same, a relationship of Fc <Fb <Fa may be formed. If the angle formed between the second arm <NUM> or the third arm <NUM> and the second base <NUM> is the same, as an angle between the rod <NUM> and the second base <NUM> increases, a force required for raising the second arm <NUM> or the third arm <NUM> may be reduced. As the rod <NUM> is connected to the lower side of the second part 820b, load applied to the motor assembly <NUM> may be reduced.

Referring to <FIG>, a rod <NUM>' may not be connected to a protrusion of a second arm <NUM>' or a protrusion of a third arm <NUM>'. If an angle formed between the second arm <NUM>' or the third arm <NUM>' and the second base <NUM> is theta S, an angle formed between the rod <NUM>' and the second base <NUM> may be referred to as theta <NUM>, and a minimum force required for the rod <NUM>' to raise the second arm <NUM>' or the third arm <NUM>' may be referred to as F1.

Referring to <FIG>, the rod <NUM> may be connected to the protrusion <NUM> of the second arm <NUM> or the protrusion <NUM> of the third arm <NUM>. If an angle formed between the second arm <NUM> or the third arm <NUM> and the second base <NUM> is theta S, an angle formed between the rod <NUM> and the second base <NUM> may be referred to as theta <NUM>, and a minimum force required for the rod <NUM> to raise the second arm <NUM> or the third arm <NUM> may be referred to as F2.

Referring to <FIG>, if theta S is the same, theta <NUM> may be greater than theta <NUM>. If theta S is the same, F1 may be greater than F2. If the angle formed between the second arms <NUM> and <NUM>' and the second base <NUM> is the same, as an angle formed between the rods <NUM> and <NUM>' and the second base <NUM> increases, a force required for raising the second arms <NUM> and <NUM>' may be reduced. As the rod <NUM> is connected to the protrusions <NUM> and <NUM>, a less force is required to raise the second arm <NUM>, compared to the case where the rod <NUM>' is not connected to the protrusions. As the rod <NUM> is connected to the protrusions <NUM> and <NUM>, load applied to the motor assembly <NUM> may be reduced.

Referring to <FIG>, the second arm <NUM> or the third arm <NUM> may have a central axis CR. When the rod <NUM> is fastened to the second arm <NUM> at a position spaced apart from the central axis CR by a distance r, an angle formed between the rod <NUM> and the second base <NUM> may be referred to as theta <NUM>, and a minimum force required for the rod <NUM> to raise the second arm <NUM> or the third arm <NUM> may be referred to as F3. When the rod <NUM> is fastened to the second arm <NUM> at a position spaced apart from the central axis CR by a distance r', an angle formed between the rod <NUM> and the second base <NUM> may be referred to as theta <NUM>', and a minimum force required for the rod <NUM> to raise the second arm <NUM> or the third arm <NUM> may be referred to as F4. When the rod <NUM> is fastened to the second arm <NUM> at a position spaced apart from the central axis CR by a distance r", an angle formed between the rod <NUM> and the second base <NUM> may be referred to as theta <NUM>", and a minimum force required for the rod <NUM> to raise the second arm <NUM> or the third arm <NUM> may be referred to as F5.

Referring to <FIG>, if theta S is the same, theta <NUM>" may be greater than theta <NUM>', and theta <NUM>' may be greater than theta <NUM>. If theta S is the same, F3 may be greater than F4, and F4 may be greater than F5. As the rod <NUM> is fastened at a position far away from the central axis CR, a force required for raising the second arm <NUM> may be reduced. As the rod <NUM> is fastened at a position far away from the central axis CR, load applied to the motor assembly <NUM> may be reduced.

Referring to <FIG>, the first arm <NUM> and the second arm <NUM> may come into contact with or may be disposed close to the rear surface of the display unit <NUM>. As the first arm <NUM> and the second arm <NUM> may come into contact with or may be disposed close to the rear surface of the display unit <NUM>, the display unit <NUM> may be stably rolled on or unrolled from the roller. The link mount <NUM> may include a first part <NUM> and a second part <NUM>. The first part <NUM> and the second part <NUM> may face each other. A space S4 may be formed between the first part <NUM> and the second part <NUM>. The first part <NUM> may face the display unit <NUM>. The first part <NUM> may be disposed closer to the display unit <NUM> than the second part <NUM>. The second arm <NUM> may be pivotally connected to a front surface of the first part <NUM>. A portion of the third arm <NUM> may be accommodated in the space S4, and may be pivotally connected to the first part <NUM> or the second part <NUM>.

Referring to <FIG>, the rod <NUM> may include a first part <NUM> and a second part <NUM>. The first part <NUM> may have a connection part 871a formed on a first side thereof. The second part <NUM> of the slide <NUM> may have a space S5 formed therein. The connection part 871a may be inserted into the space S5. The connection part 871a may be pivotally connected to the second part 820b (see <FIG>) of the slide <NUM>. A second side of the first part <NUM> may be connected to a first side of the second part <NUM>. The second side of the second part <NUM> may be pivotally connected to the second arm <NUM> or the third arm <NUM>. The first part <NUM> may have a space S3 formed therein. The first part <NUM> may have a hole 871b. The lead screw <NUM> may be accommodated in the hole 871b or the space S3.

A distance between the second part <NUM> and the display unit <NUM> may be D1. The second arm <NUM> may have a thickness of W1. A portion of the third arm <NUM> which is accommodated in the space S4 may have a thickness of W3. The thickness W3 may be equal to a distance between the first part <NUM> and the second part <NUM>. A portion of the third arm <NUM>, which is not accommodated in the space S4, may have a thickness of W2. The first part <NUM> may have a thickness of W4. The thickness W2 may be greater than the thickness W3. The thickness W2 may be equal to a sum of the thickness W3 and the thickness W4. The distance D1 may be a sum of the thickness W1 and the thickness W2.

The second arm <NUM> may come into contact with or may be disposed close to the rear surface of the display unit <NUM>. The third arm <NUM> may be disposed between the second arm <NUM> and the second part <NUM>. The third arm <NUM> allows the second part <NUM> to stably transmit power for raising the second arm <NUM>. In order to stably raise the second arm <NUM> or the third arm <NUM>, the second part <NUM> may move forward with respect to a rotation axis of the lead screw <NUM>, to be connected to the first part <NUM>. In this manner, a clearance gap between the second arm <NUM> and the second part <NUM> may be minimized.

Referring to <FIG>, a pusher <NUM> may be mounted to the link mount <NUM>. The pusher <NUM> may be referred to as a lifter <NUM>. A second part <NUM> may be fastened to a first part <NUM>. The second part <NUM> may come into contact with or may be separated from the link bracket <NUM>. The second part <NUM> may be a material having high elasticity. The first part <NUM> may be a material having lower elasticity than the second part <NUM>. The first part <NUM> may be a material having higher rigidity than the second part <NUM>. The first part <NUM> and the second part <NUM> may be collectively referred to as a head <NUM>. The head <NUM> may be disposed at the upper side of the link mount <NUM>.

A third part <NUM> may be connected to the first part <NUM>. Alternatively, the third part <NUM> may extend downwardly from the first part <NUM>. The third part <NUM> may be referred to as a tail <NUM>. A fourth part <NUM> may protrude from the third part <NUM>. The link mount <NUM> may have a space S6, and the third part <NUM> may be accommodated in the space S6. The space S6 may be opened upward. The space S6, in which the third part <NUM> is accommodated, may be next to the space S4 (see <FIG>) in which the third arm <NUM> is accommodated. The second part <NUM> of the link mount <NUM> may have a hole <NUM>. The hole <NUM> may be a long hole which is vertically elongated. The hole <NUM> may have a length of H1. The fourth part <NUM> may be inserted into the hole <NUM>. A spring <NUM> may be accommodated in the space S6. The spring <NUM> may be disposed under the third part <NUM>. The spring <NUM> may provide an elastic force to the third part <NUM> in a vertical direction.

The head <NUM> may be greater than a diameter of the space S6. When the head <NUM> is caught by an upper end of the space S6, the head <NUM> may have a minimum height from the second base <NUM>. The minimum height of the head <NUM> may be H2. When the head <NUM> has the minimum height, the fourth part <NUM> may be caught by a lower end of the space S6. When the head <NUM> has the minimum height, the spring <NUM> may provide a maximum elastic force. When the head <NUM> has the minimum height, a height of the top case <NUM> may be minimum.

While being in contact with the link bracket <NUM>, the pusher <NUM> may provide an elastic force to the link bracket <NUM>. In this manner, load applied to the motor assembly <NUM> to raise the link <NUM> may be reduced.

Referring to <FIG>, when the link <NUM> is sufficiently raised, the pusher <NUM> may be separated from the link bracket <NUM>. When the pusher <NUM> is separated from the link bracket <NUM>, the head <NUM> has a maximum height from the second base <NUM>. The maximum height of the head <NUM> may be H3. When the head <NUM> has the maximum height, the fourth part <NUM> may be stopped at an upper end of the hole <NUM> (see <FIG>). When the head <NUM> has the maximum height, the spring <NUM> may be stretched to the maximum. When the head <NUM> has the maximum height, the spring <NUM> may provide a minimum elastic force. The maximum height H3 of the head <NUM> may be substantially equal to a sum of the minimum height H2 of the head <NUM> and the length H1 of the hole.

Referring to <FIG>, the display unit <NUM> may be rolled on the roller <NUM> to the maximum. The display device <NUM> may be symmetric with respect to the motor assembly <NUM>. The top case <NUM> may have a minimum height. The slide <NUM> may be at a position closest to the inner bearing 830b. The slide <NUM> may be stopped by the first stopper 861b. The spring <NUM> may be compressed to the maximum. The pusher <NUM> may come into contact with the link bracket <NUM>. The pusher <NUM> may have a minimum height.

Referring to <FIG>, about half of the display unit <NUM> may be rolled on the roller <NUM>. The display device <NUM> may be symmetric with respect to the motor assembly <NUM>. A half of the display device <NUM> may be unrolled from the roller <NUM>. The slide <NUM> may be disposed between the first stopper 861b and the second stopper 861a. The pusher <NUM> may be separated from the link bracket <NUM>. The pusher <NUM> may have a maximum height.

Referring to <FIG>, the display unit <NUM> may be unrolled from the roller <NUM> to the maximum. The display device <NUM> may be symmetric with respect to the motor assembly <NUM>. The top case <NUM> may have a maximum height. The slide <NUM> may be disposed closest to the outer bearing 830a. The slide <NUM> may be stopped by the second stopper 861a. The spring <NUM> may be stretched to the maximum. The pusher <NUM> may be separated from the link bracket <NUM>. The pusher <NUM> may have a maximum height.

Referring to <FIG>, link mounts 920a and 920b may be mounted on the base <NUM>. The link mounts 920a and 920b may include a right link mount 920a, which is spaced rightwardly from a first right bearing 830a, and a left link mount 920b which is spaced leftwardly from a second left bearing 830d.

Links 910a and 910b may be connected to the link mounts 920a and 920b. The links 910a and 910b may include a right link 910a connected to the right link mount 920a and a left link 910b connected to the left link mount 920b.

The right link 910a may be referred to as a first link. The left link 910b may be referred to as a second link. The right link mount 920a may be referred to as a first link mount 920a. The left link mount 920b may be referred to as a second link mount 920b.

The links 910a and 910b may include first arms 911a and 911b, second arms 912a and 912b, and arm joints 913a and 913b. First sides of the second arms 912a and 912b may be rotatably connected to the link mounts 920a and 920b. Second sides of the second arms 912a and 912b may be rotatably connected to the arm joints 913a and 913b. First sides of the first arms 911a and 911b may be rotatably connected to the arm joints 913a and 913b. Second sides of the first arms 911a and 911b may be rotatably connected to link brackets 951a and 951b.

The link brackets 951a and 951b may include a right link bracket 951a connected to the first arm 911a of the right link 910a, and a left link bracket 951b connected to the first arm 911b of the left link 910b. The link brackets 951a and 951b may be connected to the upper bar <NUM>.

The upper bar <NUM> may connect the right link bracket 951a and the left link bracket 951b.

Rods 870a and 870b may connect sliders 860a and 860b with the links 910a and 910b. First sides of the rods 870a and 870b may be rotatably connected to the sliders 860a and 860b. Second sides of the rods 870a and 870b may be rotatably connected to the second arms 912a and 912b. The rods 870a and 870b may include a right rod 870a for connecting the right slider 860a and the second arm 912a of the right link 910a, and a left rod 870b for connecting the left slider 860b and the second arm 912b of the left link 910b. The right rod 870a may be referred to as a first rod 870a. The left rod 870b may be referred to as a second rod 870b.

Specifically, a structure formed by a right lead screw 840a, the right slider 860a, the right rod 870a, and the right link 910a will be described below. The right slider 860a may include a body 861a and a rod mount 862a. The body 861a may have a screw thread SS formed on an outer circumference thereof. The screw thread formed on the body 861a may be engaged with a screw thread RS of the right lead screw 840a. The right lead screw 840a may pass through the body 861a.

The rod mount 862a may be formed on the right side of the body 861a. The rod mount 862a may be rotatably connected to a first side of the right rod 870a. The rod mount 862a may include a first rod mount 862a1 and a second rod mount 862a2. The first rod mount 862a1 may be disposed at the front of the right lead screw 840a. The second rod mount 862a2 may be disposed at the rear of the right lead screw 840a. The first rod mount 862a1 and the second rod mount 862a2 may be spaced apart from each other. The second rod mount 862a2 may be spaced apart from the first rod mount 862a1 in the negative z-axis direction. The right lead screw 840a may be disposed between the first rod mount 862a1 and the second rod mount 862a2.

The rod mount 862a may be rotatably connected to a first side of the rod 870a by a connection member C1. The connection member C1 may pass through the rod mount 862a and the right rod 870a.

The right rod 870a may be rotatably connected to the second arm 912a by a connection member C2. The connection member C2 may pass through the second arm 912a and the right rod 870a.

The right rod 870a may include a transmission unit 871a connected to the second arm 912a of the right link 910a, and a cover 872a connected to the rod mount 862a of the right slider 860a. The transmission unit 871a may transmit a force, generated during movement of the right slider 860a along the right lead screw 840a, to the right link 910a.

The cover 872a may include a first plate 873a disposed at the front of the right lead screw 840a. The first plate 873a may be disposed perpendicular to the base <NUM>. Alternatively, the first plate 873a may face the right lead screw 840a.

The cover 872a may include a second plate 874a disposed at the rear of the right lead screw 840a. The second plate 874a may be disposed perpendicular to the base <NUM>. Alternatively, the second plate 874a may face the right lead screw 840a. Alternatively, the second plate 874a may be spaced apart from the first plate 873a. The right lead screw 840a may be disposed between the first plate 873a and the second plate 874a.

The cover 872a may include a third plate 875a connecting the first plate 873a and the second plate 874a. The third plate 875a may be connected to the transmission unit. The third plate 875a may be disposed over the right lead screw 840a.

The cover 872a may include a fourth plate 876a connecting the first plate 873a and the second plate 874a. The fourth plate 876a may be connected to the third plate 875a. The fourth plate 876a may be disposed over the right lead screw 840a.

A first side of the first plate 873a may be connected to the first rod mount 862a1. The first plate 873a may be connected to the first rod mount 862a1 by a connection member C1'. A second side of the first plate 873a may be connected to the third plate 875a.

A first side of the second plate 874a may be connected to the second rod mount 862a2. The second plate 874a may be connected to the second rod mount 862a2 by a connection member C1. A second side of the second plate 874a may be connected to the third plate 875a.

When the right slider 860a moves closer to the motor assembly <NUM>, the right lead screw 840a and the right rod 870a may come into contact with each other. When the right lead screw 840a and the right rod 870a come into contact with each other, mutual interference may occur, and movement of the right slider 860a may be restricted.

The cover 872a may provide the space S1 formed therein. The first plate 873a, the second plate 874a, the third plate 875a, and the fourth plate 876a may form the space S1. When the right slider 860a moves closer to the motor assembly <NUM>, the right lead screw 840a may be accommodated in the space S1 provided by the cover 872a, or may escape. By the space S1 provided by the cover 872a, the right slider 860a may move closer to the motor assembly <NUM>, compared to the case where the cover 872a is not provided. That is, as the cover 872a provides the space S1 formed therein, a movable range of the right slider 860a may be expanded. In addition, as the right lead screw 840a is accommodated in the cover 872a, there is an effect of reducing the size of the housing <NUM> (see <FIG>).

Further, the cover 872a may limit a minimum value of an angle theta S formed between the second arm 912a and the base <NUM>. When the angle theta S is sufficiently reduced, the third plate 875a of the cover 872a may come into contact with the second arm 912a and may support the second arm 912a. As the third plate 875a supports the second arm 912a, the minimum value of theta S may be limited, and sagging of the second arm 912a may be prevented. That is, the cover 872a may serve as a stopper for preventing sagging of the second arm 912a. In addition, as the third plate 875a limits the minimum value of theta S, an initial load for raising the second arm 912a may be reduced.

The lead screws 840a and 840b may be driven by one motor assembly <NUM>. As the lead screws 840a and 840b are driven by one motor assembly <NUM>, the second arms 912a and 912b may be raised while being symmetric to each other. However, when the lead screws 840a and 840b are driven by one motor assembly <NUM>, a load applied to the motor assembly <NUM> for raising the second arms 912a and 912b may be extremely increased. In this case, the third plate 875a limits the minimum value of theta S, thereby reducing the load applied to the motor assembly <NUM> for raising the second arms 912a and 912b.

A structure formed by the left lead screw 840b, the left slider 860b, the left rod 870b, and the left link 910b may be symmetric to the aforementioned structure formed by the right lead screw 840a, the right slider 860a, the right rod 870a, and the right link 910a. In this case, a symmetry axis may be a symmetry axis ys of the motor assembly <NUM>.

Referring to <FIG>, guides 850a, 850b, 850c, and 850d may be connected to the bearings 830a, 830b, 830c, and 830d. The guides 850a, 850b, 850c, and 850d may include right guides 850a and 850b disposed on the right side of the motor assembly <NUM>, and left guides 850c and 850d disposed on the left side of the motor assembly <NUM>.

First sides of the right guides 850a and 850b may be connected to the first right bearing 830a, and second sides thereof may be connected to the second right bearing 830b. The right guides 850a and 850b may be disposed parallel to the right lead screw 840a. Alternatively, the right guides 850a and 850b may be spaced apart from the right lead screw 840a.

The right guides 850a and 850b may include a first right guide 850a and a second right guide 850b. The first right guide 850a and the second right guide 850b may be spaced apart from each other. The right lead screw 840a may be disposed between the first right guide 850a and the second right guide 850b.

The right slider 860a may include a protrusion. Alternatively, the display device may include a protrusion formed on the right slider 860a. The protrusion may be formed on the body of the slider. The protrusion may include a front protrusion (not shown) protruding from the body 861a of the right slider 860a in the positive z-axis direction, and a rear protrusion 865a protruding from the body of the slider in the negative z-axis direction.

The first right guide 850a may pass through the rear protrusion 865a. Alternatively, a first hole 863a formed in the rear protrusion may be included, and the first right guide 850a may pass through the first hole 863a. The first hole 863a may be formed in the x-axis direction. The first hole 863a may be referred to as a hole 863a.

The second right guide (not shown) may pass through the front protrusion (not shown). Alternatively, a second hole (not shown) formed in the front protrusion may be included, and the second right guide may pass through the second hole. The second hole may be formed in the x-axis direction.

When the right slider 860a moves along the right lead screw 840a, the right guides 850a and 50b may guide more stable movement. As the right guides 850a and 850b stably guide the right slider 860a, the right slider 860a may move along the right lead screw 840a without rotating with respect to the right lead screw 840a.

A structure formed by the left guides 850c and 850d, the left bearings 830a, 830b, 830c, and 830d, the left slider 860b, and the left lead screw 840b may be symmetric to the aforementioned structure formed by the right guides 850a and 850b, the right bearings 830a, 830b, 830c, and 830d, the right slider 860a, and the right lead screw 840a. In this case, a symmetry axis may be a symmetry axis ys of the motor assembly <NUM>.

Referring to <FIG>, first springs 841a and 841b may be inserted into the lead screws 840a and 840b. Alternatively, the lead screws 840a and 840b may pass through the first springs 841a and 841b. The first springs 841a and 841b may include a first right spring 841a disposed on the right side of the motor assembly <NUM>, and a first left spring 841b disposed on the left side of the motor assembly <NUM>.

The first right spring 841a may be disposed between the right slider 860a and the second right bearing 830b. A first end of the first right spring 841a may come into contact or may be separated from the right slider 860a. A second end of the first right spring 841a may come into contact or may be separated from the second right bearing 830b.

When the second arm 912a fully lies with respect to the base <NUM>, a distance between the right slider 860a and the second right bearing 830b may be a distance RD3. While not being compressed or stretched, the first right spring 841a may have a greater length than the distance RD3. Accordingly, when the second arm 912a fully lies with respect to the base <NUM>, the first right spring 841a may be compressed between the right slider 860a and the second right bearing 830b. Further, the first right spring 841a may provide a restoring force to the right slider 860a in the positive x-axis direction.

When the second arm 912a changes from a fully lying position to a raised position with respect to the base <NUM>, the restoring force provided by the first right spring 841a may assist in raising the second arm 912a. As the first right spring 841a assists in raising the second arm 912a, load applied to the motor assembly <NUM> may be reduced.

The lead screws 840a and 840b may be driven by one motor assembly <NUM>. As the lead screws 840a and 840b are driven by one motor assembly <NUM>, the second arms 912a and 912b may be raised while being symmetric to each other. However, when the lead screws 840a and 840b are driven by one motor assembly <NUM>, a load applied to the motor assembly <NUM> for raising the second arms 912a and 912b may be extremely increased. In this case, the first right spring 841a assists in raising the second arm 912a, thereby reducing the load on the motor assembly <NUM> and the load applied to the motor assembly <NUM> for raising the second arm 912a.

Alternatively, when the second arm 912a changes from a raised position to a fully lying position with respect to the base <NUM>, the restoring force provided by the first right spring 841a may lessen the impact caused when the second arm 912a lies with respect to the base <NUM>. That is, when the second arm 912a lies with respect to the base <NUM>, the first right spring 841a may act as a damper. As the first right spring 841a acts as a damper, the load on the motor assembly <NUM> may be reduced.

A structure formed by the first left spring 841b, the left bearings 830a, 830b, 830c, and 830d, the left slider 860b, the left lead screw 840b, and the second arm 912a may be symmetric to the aforementioned structure formed by the first right spring 841a, the right bearings 830a, 830b, 830c, and 830d, the right slider 860a, the right lead screw 840a, and the second arm 912a. In this case, a symmetry axis may be a symmetry axis ys of the motor assembly <NUM>.

Referring to <FIG>, the second springs 851a and 851b may be inserted into the guides 850a, 850b, 850c, and 850d. Alternatively, the guides 850a, 850b, 850c, and 850d may pass through the second springs 851a and 851b. The second springs 851a and 851b may include a second right spring 851a disposed on the right side of the motor assembly <NUM>, and a second left spring 851b disposed on the left side of the motor assembly <NUM>.

There may be a plurality of second right springs 851a. The second right springs 851a may include springs 940a and 940b inserted into the first right guide 850a, and springs 940a and 940b inserted into the second right guide 850b. Alternatively, the second right springs 851a may include springs 940a and 940b through which the first right guide 850a passes, and springs 940a and 940b through which the second right guide 850b passes.

The guides 850a, 850b, 850c, and 850d may include stopper protrusions 852a and 852b. The stopper protrusions 852a and 952b may include a right stopper protrusion 852a disposed on the right side of the motor assembly <NUM>, and a left stopper protrusion 852b disposed on the left side of the motor assembly <NUM>.

The right stopper protrusion 852a may be disposed between the right slider 860a and the second right bearing 830b. Further, the second right spring 851a may be disposed between the right slider 860a and the second right bearing 830b. A first end of the second right spring 851a may come into contact with or may be separated from the right slider 860a. A second end of the second right spring 851a may come into contact with or may be separated from the right stopper protrusion 852a.

When the second arm 912a fully lies with respect to the base <NUM>, a distance between the right slider 860a and the right stopper protrusion 852a may be a distance RD4. While not being compressed or stretched, the second right spring 851a may have a greater length than the distance RD4. Accordingly, when the second arm 912a fully lies with respect to the base <NUM>, the second right spring 851a may be compressed between the right slider 860a and the second stopper protrusion 852a. Further, the second right spring 851a may provide a restoring force to the right slider 860a in the positive x-axis direction.

When the second arm 912a changes from a fully lying position to a raised position with respect to the base <NUM>, the restoring force provided by the second right spring 851a may assist in raising the second arm 912a. As the second right spring 851a assists in raising the second arm 912a, load applied to the motor assembly <NUM> may be reduced.

The lead screws 840a and 840b may be driven by one motor assembly <NUM>. As the lead screws 840a and 840b are driven by one motor assembly <NUM>, the second arms 912a and 912b may be raised while being symmetric to each other. However, when the lead screws 840a and 840b are driven by one motor assembly <NUM>, a load applied to the motor assembly <NUM> for raising the second arms 912a and 912b may be extremely increased. In this case, the second right spring 851a assists in raising the second arm 912a, thereby reducing the load on the motor assembly <NUM> and the load applied to the motor assembly <NUM> for raising the second arm 912a.

Alternatively, when the second arm 912a changes from a raised position to a fully lying position with respect to the base <NUM>, the restoring force provided by the second right spring 851a may lessen the impact caused when the second arm 912a lies with respect to the base <NUM>. That is, when the second arm 912a lies with respect to the base <NUM>, the second right spring 851a may act as a damper. As the second right spring 851a acts as a damper, the load of the motor assembly <NUM> may be reduced.

A structure formed by the second left spring 851b, the left stopper protrusion 852b, the left slider 860b, the left guides 850c and 850d, and the second arm 912a may be symmetric to the aforementioned structure formed by the second right spring 851a, the right stopper protrusion 852a, the right slider 860a, the right guides 850a and 850b, and the second arm 912a. In this case, a symmetry axis may be a symmetry axis ys of the motor assembly <NUM>.

Referring to <FIG>, the second arm 912a may be raised by receiving the restoring force from the first right spring 841a and the second right spring 851a.

An angle formed between the second arm 912a and the base <NUM> may be an angle theta S. An angle formed between the right rod 870a and the base <NUM> may be an angle theta T. A force required for the motor assembly <NUM> to move the right slider 860a in the positive x-axis direction may be FA. A force applied by the first right spring 841a to the right slider 860a may be FB. A force applied by the second right spring 851a to the right slider 860a may be FC. A force transmitted by the right rod 870a to the second arm 912a may be FT.

When the second arm 912a fully lies with respect to the base <NUM>, the angles theta S and theta T may have minimum values. When the second arm 912a changes from a fully lying position to a raised position with respect to the second base <NUM>, the angles theta S and theta T may gradually increase.

When the second arm 912a fully lies with respect to the base <NUM>, the first right spring 841a may be compressed. The compressed first right spring 841a may provide the restoring force FB to the right slider 860a. The restoring force FB may be applied in the positive x-axis direction. When the second arm 912a fully lies with respect to the base <NUM>, compression displacement of the first right spring 841a may be maximum, and a magnitude of the restoring force FB may have a maximum value. When the second arm 912a changes from a fully lying position to a raised position with respect to the base <NUM>, the compression displacement of the first right spring 841a may gradually decrease, and the magnitude of the restoring force FB may gradually decrease.

When the second arm 912a fully lies with respect to the base <NUM>, the second right spring 851a may be compressed. The compressed second right spring 851a may provide the restoring force FC to the right slider 860a. The restoring force FC may be applied in the positive x-axis direction. When the second arm 912a fully lies with respect to the base <NUM>, compression displacement of the second right spring 851a may be maximum, and a magnitude of the restoring force FC may have a maximum value. When the second arm 912a changes from a fully lying position to a raised position with respect to the base <NUM>, the compression displacement of the second right spring 851a may gradually decrease, and the magnitude of the restoring force FC may gradually decrease.

The force FT transmitted by the right rod 870a to the second arm 912a may be a resultant force composed of the force FA required for the motor assembly <NUM> to move the right slider 860a in the positive x-axis direction, the restoring force FB of the first right spring 841a, and the restoring force FC of the second right spring 851a.

When the second arm 912a starts to be raised after fully lying with respect to the base <NUM>, the motor assembly <NUM> may be under a maximum load. In this case, a magnitude of the restoring force FB provided by the first right spring 841a may be maximum. Further, the restoring force FC provided by the second springs 851a and 851b may be maximum.

When the second arm 912a changes from a fully lying position to a raised position with respect to the base <NUM>, the restoring force provided by the first right spring 841a and the second right spring 851a may assist in raising the second arm 912a. As the first right spring 841a and the second right spring 851a assist in raising the second arm 912a, the load on the motor assembly <NUM> may be reduced.

The first right spring 841a and the second right spring 851a may simultaneously provide the restoring force (a resultant force of the restoring force FB and the restoring force FC) to the right slider 860a. The restoring force (the resultant force of the restoring force FB and the restoring force FC) may be provided to the right slider 860a until a distance RD5 between the right slider 860a and the right stopper protrusion 852a becomes equal to a length of the second right spring 851a.

When the distance RD5 between the right slider 860a and the right stopper protrusion 852a becomes equal to the length of the second right spring 851a, compression displacement of the second right spring 851a may become zero. When the compression displacement of the second right spring 851a becomes zero, the restoring force FC provided by the second right spring 851a to the right slider 860a may become zero.

When the distance RD5 between the right slider 860a and the right stopper protrusion 852a is greater than the length of the second right spring 851a, only the first right spring 841a may provide the restoring force FB to the right slider 860a. The restoring force FB may be provided to the right slider 860a until a distance RD6 between the right slider 860a and the second right bearing 830b becomes equal to a length of the first right spring 841a.

When the distance RD6 between the right slider 860a and the right second bearing 830b becomes equal to the length of the first right spring 841a, compression displacement of the first right spring 841a may become zero. When the compression displacement of the first right spring 841a becomes zero, the restoring force FB provided by the first right spring 841a to the right slider 860a may become zero.

When the distance RD6 between the right slider 860a and the second right bearing 830b is greater than the length of the first right spring 841a, the motor assembly <NUM> may raise the second arm 912a without receiving the restoring force from the first right spring 841a or the second right spring 851a.

A structure formed by the first left spring 841b, the second left spring 851b, the left stopper protrusion 852b, the left slider 860b, the left guides 850c and 850d, the left lead screw 840b, the left rod 870b, and the second arm 912a may be symmetric to the aforementioned structure formed by the first right spring 841a, the second right spring 851a, the right stopper protrusion 852a, the right slider 860a, the right guides 850a and 850b, the right lead screw 840a, the right rod 870a, and the second arm 912a. In this case, a symmetry axis may be a symmetry axis ys of the motor assembly <NUM>.

Referring to <FIG>, pushers 930a and 930b may be connected to the link mounts 920a and 920b. The pushers 930a and 930b may include a right pusher 930a disposed on the right side of the motor assembly <NUM>, and a left pusher 930b disposed on the left side of the motor assembly <NUM>.

The link mounts 920a and 920b may form an accommodation space A. The accommodation space A may serve to accommodate the springs 940a and 940b and the pushers 930a and 930b. The springs 940a and 940b may include the right spring 940a disposed on the right side of the motor assembly <NUM>, and a left spring 940b disposed on the left side of the motor assembly <NUM>. The accommodation space A may be referred to as an internal space A.

The link mounts 920a and 920b may have a first hole 922a for connecting the accommodation space A and an external space (a first hole corresponding to the link mount 920b is not shown). The first hole 922a may be formed in an upper surface of the link mounts 920a and 920b. The first hole 922a may be referred to as a hole 922a.

The pushers 930a and 930b may be disposed perpendicular to the base <NUM>. Alternatively, the pushers 930a and 930b may be disposed parallel to the y-axis. The springs 940a and 940b may be disposed perpendicular to the base <NUM>. Alternatively, the springs 940a and 940b may be disposed parallel to the y-axis.

The pushers 930a and 930b may include first parts 931a and 931b and second parts 932a and 932b. The second parts 932a and 932b may be connected to lower sides of the first parts 931a and 931b. Lower ends of the second parts 932a and 932b may be connected to the springs 940a and 940b. All or a portion of the second parts 932a and 932b may be accommodated in the accommodation space A formed by the link mounts 920a and 920b. The second parts 932a and 932b may have the same diameter as a diameter of the first hole 922a, or may have a smaller diameter than the diameter of the first hole 922a. The second parts 932a and 932b may pass through the first hole 922a.

The first parts 931a and 931b may be disposed outside of the link mounts 920a and 920b. Alternatively, the first parts 931a and 931b may be disposed outside of the accommodation space A of the link mounts 920a and 920b. The first parts 931a and 931b may have a greater diameter than the diameter of the first hole 922a.

The first parts 931a and 931b may come into contact with or may be separated from the link brackets 951a and 951b. For example, when the second arms 912a and 912b fully lie with respect to the base <NUM>, the first parts 931a and 931b may come into contact with the link brackets 951a and 951b. Alternatively, when second arms 912a and 912b are fully raised with respect to the base <NUM>, the first parts 931a and 931b may be separated from the link brackets 951a and 951b.

When the first parts 931a and 931b come into contact with the link brackets 951a and 951b, the pushers 930a and 930b may receive force from the link brackets 951a and 951b. The pushers 930a and 930b may receive a downward force. The pushers 930a and 930b may receive the force in the negative y-axis direction. Alternatively, the link brackets 951a and 951b may press the pushers 930a and 930b. The link brackets 951a and 951b may downwardly press the pushers 930a and 930b. Alternatively, the link brackets 951a and 951b may press the pushers 930a and 930b in the negative y-axis direction.

When the first parts 931a and 931b receive the force, the springs 940a and 940b may be compressed. The compressed springs 940a and 940b may provide a restoring force to the pushers 930a and 930b. The restoring force may be opposite to a direction of the force applied to the first parts 931a and 931b. Alternatively, the restoring force may be applied in the positive y-axis direction.

The link mounts 920a and 920b may have a second hole 921a (a second hole corresponding to the link mount 920b is not shown). The second hole 921a may connect the accommodation space A and an external space. All or a portion of the springs 940a and 940b may be exposed to the outside through the second hole 921a. All or a portion of the pushers 930a and 930b may be exposed to the outside through the second hole 921a. During maintenance or repair of the display device, service providers may check an operating state of the pushers 930a and 30b through the second hole 921a. The second hole 921a may provide convenience in repair and maintenance for the service providers.

Referring to <FIG>, the right link 910a may be raised by receiving a restoring force from the right pusher 930a. The following description will be given based on the right link 910a.

An angle formed between the second arm 912a and the base <NUM> may be an angle theta S. A force transmitted by the right rod 870a to the second arm 912a may be FT. A force transmitted by the right pusher 930a to the right link bracket 951a may be FP.

Referring to <FIG>, when the second arm 912a fully lies with respect to the base <NUM>, the angle theta S may have a minimum value. The right spring 940a connected to the right pusher 930a may be compressed to the maximum, and a magnitude of the restoring force FP may have a maximum value. The compressed right spring 940a may provide the restoring force FP to the right pusher 930a. The right pusher 930a may transmit the restoring force FP to the right link bracket 951a. The restoring force FP may be applied in the positive y-axis direction.

When the second arm 912a fully lies with respect to the base <NUM>, a distance HL from the base <NUM> to the right pusher 930a may have a minimum value. The first part 931a of the right pusher 930a may protrude to the outside of the right link mount 920a, and all of the second part 932a of the right pusher 930a may be accommodated in an accommodation space 923a of the right link mount 920a.

Referring to <FIG>, when the second arm 912a changes from a fully lying position to a raised position with respect to the base <NUM>, the angle theta S may gradually increase. Compression displacement of the right spring 940a may gradually decrease, and a magnitude of the restoring force FP may gradually decrease.

As the angle theta S gradually increases, at least a portion of the second part 932a of the right pusher 930a may protrude to the outside of the right link mount 920a. A length of the right pusher 930a that protrudes to the outside of the right link mount 920a may be referred to as a length HP. A distance HL from the base <NUM> to an upper end of the right pusher 930a may increase by HP, compared to the case where the second arm 912a fully lies with respect to the base <NUM>.

Referring to <FIG>, while the second arm 912a is raised with respect to the base <NUM>, the right pusher 930a and the right link bracket 951a may be separated from each other. The compression displacement of the right spring 940a may become zero. When the compression displacement of the right spring 940a becomes zero, the restoring force FP provided by the right pusher 930a to the right link bracket 951a may become zero.

In addition, the length HP of the second part 932a of the right pusher 930a that protrudes to the outside of the right link mount 920a, may have a maximum value. Further, the distance HL from the base <NUM> to the upper end of the right pusher 930a may have a maximum value.

That is, while the right pusher 930a and the right link bracket 951a are in contact with each other, the right pusher 930a applies a restoring force to the right link bracket 951a, thereby assisting in raising the second arm 912a, and reducing the load on the motor assembly <NUM>.

The lead screws 840a and 840b may be driven by one motor assembly <NUM>. As the lead screws 840a and 840b are driven by one motor assembly <NUM>, the second arms 912a and 912b may be raised while being symmetric to each other. However, when the lead screws 840a and 840b are driven by one motor assembly <NUM>, a load applied to the motor assembly <NUM> for raising the second arms 912a and 912b may be extremely increased. In this case, the right pusher 930a applies the restoring force to the right link bracket 951a, thereby assisting in raising the second arm 912a, and reducing the load on the motor assembly <NUM>.

Alternatively, when the second arm 912a changes from a raised position to a fully lying position with respect to the base <NUM>, the restoring force provided by the right pusher 930a to the right link bracket 951a may lessen the impact caused when the second arm 912a lies with respect to the base <NUM>. That is, the restoring force provided by the right pusher 930a to the right link bracket 951a may act as a damper when the second arm 912a lies with respect to the base <NUM>. As the right pusher 930a acts as a damper, the load on the motor assembly <NUM> may be reduced.

A structure formed by the left pusher 930b, the left spring 940b, the left link bracket 951b, the left link mount 920b, and the left rod 870b may be symmetric to the aforementioned structure formed by the right pusher 930a, the right spring 940a, the right link bracket 951a, the right link mount 910a, and the right rod 870a. In this case, a symmetry axis may be a symmetry axis ys of the motor assembly <NUM>.

Referring to <FIG>, the panel roller <NUM> may be mounted on the base <NUM>. The panel roller <NUM> may be mounted in front of the lead screws 840a and 840b. Alternatively, the panel roller <NUM> may be disposed parallel to a longitudinal direction of the lead screws <NUM> and 840b. Alternatively, the panel roller <NUM> may be spaced apart from the lead screws 840a and 840b.

The display unit <NUM> may include the display panel <NUM> and the module cover <NUM>. A lower side of the display unit <NUM> may be connected to the panel roller <NUM>, and an upper side of the display unit <NUM> may be connected to the upper bar <NUM>. The display unit <NUM> may be rolled on or unrolled from the panel roller <NUM>.

A distance from the symmetry axis ys of the motor assembly <NUM> to the right slider 860a may be a distance RD. A distance from the symmetry axis ys of the motor assembly <NUM> to the left slider 860b may be a distance LD. A distance from the right slider 860a to the left slider 860b may be a distance SD. The distance SD may be a sum of the distance RD and the distance LD. A distance from the base <NUM> to the upper end of the display unit <NUM> may be a distance HD.

Referring to <FIG>, when the second arms 912a and 912b fully lie with respect to the base <NUM>, the distance SD between the right slider 860a and the left slider 860b may have a minimum value. The distance RD from the symmetry axis ys of the motor assembly <NUM> to the right slider 860a may be equal to the distance LD from the symmetry axis ys of the motor assembly <NUM> to the left slider 860b.

When the second arms 912a and 912b fully lie with respect to the base <NUM>, the distance HD from the base <NUM> to the upper end of the display unit <NUM> may have a minimum value.

When the second arms 912a and 912b fully lie with respect to the base <NUM>, the first springs 841a and 841b may come into contact with the sliders 860a and 860b. Further, the second springs 851a and 851b may come into contact with the sliders 860a and 860b. In addition, the pushers 930a and 930b may come into contact with the link brackets 951a and 951b.

When the second arms 912a and 912b fully lie with respect to the base <NUM>, an amount of compression of the first springs 841a and 841b may have a maximum value, and a magnitude of the restoring force provided by the first springs 841a and 841b to the sliders 860a and 860b may have a maximum value.

When the second arms 912a and 912b fully lie with respect to the base <NUM>, an amount of compression of the second springs 851a and 851b may have a maximum value, and a magnitude of the restoring force provided by the second springs 851a and 851b to the sliders 860a and 860b may have a maximum value.

When the second arms 912a and 912b fully lie with respect to the base <NUM>, an amount of compression of the springs 940a and 940b may have a maximum value, and a magnitude of the restoring force provided by the springs 940a and 940b to the pushers 930a and 930b may have a maximum value.

When the second arms 912a and 912b start to be raised with respect to the base <NUM>, the second arms 912a and 912b may be raised by receiving the restoring force from the first springs 841a and 841b, the second springs 851a and 851b, and springs 940a and 940b. In this manner, the load applied to the motor assembly <NUM> may be reduced.

Referring to <FIG>, while the second arms 912a and 912b are raised with respect to the base <NUM>, the distance SD between the right slider 860a and the left slider 860b may gradually increase. Even when the distance SD increases, the distance LD and the distance RD may be equal to each other. That is, the right slider 860a and the left slider 860b may be disposed symmetrical to each other with respect to the symmetry axis ys of the motor assembly <NUM>. In addition, a raised degree of the second arms 912a and 912b of the right link 910a with respect to the base <NUM> may be equal to a raised degree of the second arms 912a and 912b of the left link 910b with respect to the base <NUM>.

While the second arms 912a and 912b are raised with respect to the base <NUM>, the distance HD from the base <NUM> to the upper end of the display unit <NUM> may gradually increase. The display unit <NUM> may be unrolled from the panel roller <NUM>. Alternatively, the display unit <NUM> may be unfolded from the panel roller <NUM>.

When the second arms 912a and 912b are sufficiently raised with respect to the base <NUM>, the first springs 841a and 841b may be separated from the sliders 860a and 860b. In addition, when the second arms 912a and 912b are sufficiently raised with respect to the base <NUM>, the second springs 851a and 851b may be separated from the sliders 860a and 860b. Further, when the second arms 912a and 912b are sufficiently raised with respect to the base <NUM>, the pushers 930a and 930b may be separated from the link brackets 951a and 951b.

Separation of the first springs 841a and 841b from the sliders 860a and 860b, separation of the second springs 851a and 851b from the sliders 860a and 860b, and separation of the pushers 930a and 930b from the link brackets 951a and 951b may be performed independently of each other. That is, a sequence of separation of the first springs 841a and 841b from the sliders 860a and 860b, separation of the second springs 851a and 851b from the sliders 860a and 860b, and separation of the pushers 930a and 930b from the link brackets 951a and 951b may vary.

An angle formed between an axis xs1 parallel to the base <NUM> and the second arm 912a may be referred to as theta R. Further, an angle formed between the axis xs1 parallel to the base <NUM> and the first arm 911a may be referred to as theta R'. The axis xs1 may be parallel to the x axis.

When the second arm 912a fully lies with respect to the base <NUM>, or while the second arm 912a is raised with respect to the base <NUM>, or when raising of the second arm 912a with respect to the base <NUM> is complete, theta R and theta R' may be maintained equal to each other.

An angle formed between an axis xs2 parallel to the base <NUM> and the second arm 912b may be referred to as theta L. Further, an angle formed between the axis xs2 parallel to the base <NUM> and the first arm 911b may be referred to as theta L'. The axis xs2 may be parallel to the x axis.

When the second arm 912b fully lies with respect to the base <NUM>, or while the second arm 912b is raised with respect to the base <NUM>, or when raising of the second arm 912a with respect to the base <NUM> is complete, theta L and theta L' may be maintained equal to each other.

The axis xs1 and the axis xs2 may be the same axis.

Referring to <FIG>, when the second arms 912a and 912b are fully raised with respect to the base <NUM>, the distance SD between the right slider 860a and the left slider 860b may have a maximum value. Even when the distance SD has the maximum value, the distance LD and the distance RD may be equal to each other.

When the second arms 912a and 912b are fully raised with respect to the base <NUM>, the distance HD from the base <NUM> to the upper end of the display unit <NUM> may have a maximum value.

Referring to <FIG> and <FIG>, a door assembly <NUM> is be mounted in the housing <NUM> at a position adjacent to an upper plate of the housing <NUM>. A door <NUM> covers an opening 30P of the upper plate of the housing <NUM>. The opening 30P of the upper plate of the housing <NUM> may be elongated in a longitudinal direction of the housing <NUM> on the upper plate of the housing <NUM>. A door <NUM> may be an elongated plate. The door <NUM> may move by sliding in a forward and backward direction of the housing <NUM>. A holder <NUM> may be coupled to the door <NUM>. A first side of the holder <NUM> may be fixed to a lower surface of the door <NUM>. In this case, the holder <NUM> may be disposed adjacent to a right end in a longitudinal direction of the door <NUM>. The holder <NUM> may be referred to as a door holder <NUM>.

The holder <NUM> may be coupled to a slider <NUM>. A second side of the holder <NUM> may be fixed to the slider <NUM>. The slider <NUM> may move on a rail <NUM>. The rail <NUM> may be fixed to a lower side of the upper plate of the housing <NUM>. The rail <NUM> may have slots <NUM> extending in the forward and backward direction of the housing <NUM>. The slider <NUM> is inserted into the slots <NUM> and may move in an extended direction of the slots <NUM>. A rack gear 43R may be formed on a lower surface of the slider <NUM>.

A shaft gear <NUM> may include a first gear 45a and a second gear 45b. The first gear 45b may be engaged with the rack gear 43R, and the second gear 45a may be fixed to the first gear 45b. For example, the first gear 45b and the second gear 45a may be integrally formed with each other. A shaft <NUM> may be inserted into the first gear 45a and the second gear 45b. The shaft <NUM>, the first gear 45a, and the second gear 45b may rotate together.

A motor <NUM> provides torque. For example, the motor <NUM> may provide a torque of <NUM>·m. The motor <NUM> may be mounted in the housing <NUM>. The motor <NUM> may be connected to a worm <NUM>. When the motor <NUM> rotates, the worm <NUM> may rotate. A worm gear <NUM> may be engaged with the worm <NUM> connected to the motor <NUM>. The worm gear <NUM> may be connected to a torque limiter <NUM>. For example, the torque limiter <NUM> may limit a torque exceeding <NUM>·m. The torque limiter <NUM> may be connected to the shaft gear <NUM>. For example, the torque limiter <NUM> may be engaged with the second gear 45a of the shaft gear <NUM>.

When the motor <NUM> rotates, the worm <NUM> may provide power to the worm gear <NUM>. Accordingly, when driving of the door <NUM> is interrupted, it is possible to prevent damage to the mechanism and injury caused when a user's hand is caught, and the like.

Referring to <FIG> and <FIG>, the shaft <NUM> is elongated in the longitudinal direction of the housing <NUM> (see <FIG>). The shaft gear <NUM> (see <FIG>) may be coupled to both ends of the shaft <NUM>. The shaft <NUM> may include a shaft body <NUM> and gear coupling parts <NUM> and <NUM>. The gear coupling parts <NUM> and <NUM> may include a first part <NUM> and a second part <NUM>. The first part <NUM> may have a smaller diameter than a diameter of the shaft body <NUM>. The first part <NUM> may include fixing parts <NUM> and <NUM>. The fixing parts <NUM> and <NUM> may be formed by cutting out an outer circumferential surface of the first part <NUM>. The second part <NUM> may have a smaller diameter than a diameter of the first part <NUM>.

The gear coupling parts <NUM> and <NUM> may include first gear coupling parts 52a and 52a and second gear coupling parts 52b and 53b. The first gear coupling parts 52a and 53a may be formed at a first end of the shaft body <NUM>, and the second gear coupling parts 52b and 53b may be formed at a second end of the shaft body <NUM>. For example, the gear coupling parts <NUM> and <NUM> may be sequentially processed. As a second end of the shaft <NUM> is fixed to a shelf jig, the first gear coupling parts 52a and 53a may be formed at a first end of the shaft <NUM>. After the first gear coupling parts 52a and 53a are formed, the first end of the shaft <NUM> is fixed to the shelf jig, and then the second gear coupling parts 52b and 53b may be formed at the second end of the shaft <NUM>. In this case, it may be difficult for the first gear coupling parts 52a and 53a and the second gear coupling parts 52b and 53b to have a concentric axis. In this case, vibration and noise may occur during rotation of the shaft <NUM>.

In the case where the shaft <NUM> is formed as a polygonal shaft having a polygonal cross-section, a concentric axis may be provided when the aforementioned shaft <NUM> is formed, but there may be a problem in that when the shaft <NUM> rotates, the shaft <NUM> may be caught by a holder <NUM> (see <FIG>) holding the shaft <NUM>.

Referring to <FIG>, if the shaft <NUM> is reduced in length, vibration and noise occurring during rotation of the shaft <NUM> may be reduced even when the gear coupling parts <NUM> and <NUM> do not have a concentric axis. A first shaft 50a is coupled to a second shaft 50b by a joint <NUM>. The joint <NUM> may include an insertion-fixing portion 59I, into which the first coupling parts 52a and 53a and the second coupling parts 52b and 53b are inserted and fixed. Here, when torque applied to the shaft <NUM> increases, the shafts <NUM> run idle in the joint <NUM>, thereby leading to a loss of power.

Referring to <FIG>, the shaft <NUM> may include the shaft body <NUM>, the gear coupling parts <NUM> and <NUM>, and a joint hole <NUM>. The shaft body <NUM> may be an elongated bar. The gear coupling parts <NUM> and <NUM> may be formed at the first end of the shaft body <NUM>. The gear coupling parts <NUM> and <NUM> may include the first part <NUM> and the second part <NUM>. The first part <NUM> may have a smaller diameter than a diameter of the shaft body <NUM>. The first part <NUM> may include a fixing part <NUM>. The fixing part <NUM> may be formed by cutting out an outer circumferential surface of the first part <NUM>. The fixing part <NUM> may include a first fixing part 521a formed by cutting out a portion of the outer circumferential surface of the first part <NUM>, and a second fixing part 521b formed opposite to the first fixing prat 521a with respect to a central axis of the first part <NUM>. The second part <NUM> may have a smaller diameter than a diameter of the first part <NUM>.

The joint hole <NUM> may be formed at a position adjacent to the second end of the shaft body <NUM>. The joint hole <NUM> may be formed by passing through both sides of the outer circumferential surface of the shaft body <NUM>. The joint hole <NUM> may be formed in a direction perpendicular to a central axis of the shaft body <NUM>.

Referring to <FIG> and <FIG>, the joint <NUM> includes a body <NUM> and locking pins <NUM> and <NUM>. The body <NUM> has an elongated cylindrical shape. An inclined surface 61a may be formed between an upper surface and an inner circumferential surface at both ends of the body <NUM>. Accordingly, the shaft <NUM> (see <FIG>) may be easily inserted.

The locking pins <NUM> and <NUM> may pass through the outer and inner circumferential surfaces of the body <NUM> in a direction perpendicular to an axial direction of the body <NUM>. First ends of the locking pins <NUM> and <NUM> may protrude to the outer circumferential surface on a first side of the body <NUM>, and second ends of the locking pints <NUM> and <NUM> may protrude to the outer circumferential surface on a second side of the body <NUM>. The first ends of the locking pins <NUM> and <NUM> may be disposed opposite to the second ends of the locking pins <NUM> and <NUM> with respect to the body <NUM>. The locking pins <NUM> and <NUM> may have slits <NUM> and <NUM>. The slits <NUM> and <NUM> may be formed by cutting the outer and inner circumferential surfaces of the locking pins <NUM> and <NUM> in a longitudinal direction of the locking pins <NUM> and <NUM>. There may be a plurality of locking pins <NUM> and <NUM>. A first locking pin <NUM> may be disposed adjacent to a first end of the body <NUM>, and a second locking pin <NUM> may be disposed adjacent to a second end of the body <NUM>.

The first shaft 50a is inserted into the joint <NUM> in a longitudinal direction of the joint <NUM>. The second shaft 50b may be inserted into the joint <NUM> in the longitudinal direction of the joint <NUM>. The first shaft 50a may be disposed opposite to the second shaft 50b with respect to the joint <NUM>. An end surface of the first shaft 50a may face an end surface of the second shaft 50b. The joint holes <NUM> (see <FIG>) of the shafts 50a and 50b are aligned at positions of the locking pins <NUM> and <NUM>.

Referring to <FIG>, press-fit pins f1 and f2 may be inserted into the locking pins <NUM> and <NUM>. A diameter of the press-fit pins f1 and f2 may be greater than an inner diameter of the locking pins <NUM> and <NUM>. As the press-fit pins f1 and f2 are inserted into the locking pins <NUM> and <NUM>, the locking pins <NUM> and <NUM> may increase in diameter. Accordingly, the locking pins <NUM> and <NUM> may firmly fix the body <NUM> of the joint <NUM> and the shafts 50a and 50b. The joint <NUM> may be held in the holder <NUM>. The joint <NUM> may be rotated in the holder <NUM>.

The holder <NUM> may include a body 60H1 and hangers 60H2 and 60H3. The hangers 60H2 and 60H3 may be formed at the body 60H1. An inner diameter of the hangers 60H2 and 60H3 may correspond to an outer diameter of the joint <NUM>. The hangers 60H2 and 60H3 may hold the joint <NUM>, and the joint <NUM> may be rotated at a position fixed by the hangers 60H2 and 60H3. A first hanger 60H2 may be formed in an arch shape on one surface of the body 60H1. A second hanger 60H3 may be formed in an arch shape on the other surface of the body 60H1. The second hanger 60H3 may be spaced apart from the first hanger 60H2 by a first distance D1. The first hanger 60H2 may have a first width D2, and the second hanger 60H3 may have a second width D3. A sum of the first width D2, the second width D3, and the first distance D1 may be smaller than a gap between the locking pins f1 and f2.

Referring to <FIG>, the shaft <NUM> may be rotated in the holder <NUM>. The shaft <NUM> may be held in the holder <NUM>. The holder <NUM> may include the body 60H1 and the hangers 60H2 and 60H3. The hangers 60H2 and 60H3 may be formed at the body 60H1. An inner diameter of the hangers 60H2 and 60H3 may correspond to an outer diameter of the shaft <NUM>. The hangers 60H2 and 60H3 may hold the shaft <NUM>, and the shaft <NUM> may be rotated at a position fixed by the hangers 60H2 and 60H3. The first hanger 60H2 may be formed in an arch shape on one surface of the body 60H1. The second hanger 60H3 may be formed in an arch shape on the other surface of the body 60H1. The second hanger 60H3 may be spaced apart from the first hanger 60H2 by a first distance D1. The first hanger 60H2 may have a first width D2, and the second hanger 60H3 may have a second width D3.

Referring to <FIG> and <FIG>, a first shaft gear <NUM> may be mounted adjacent to the motor <NUM> and may receive a driving force from the motor <NUM>. The first shaft gear <NUM> may be fixed to the first shaft 50a to provide torque to the first shaft 50a. The first shaft 50a may be elongated in the left-to-right direction of the housing <NUM> and may be held by the first holder <NUM>.

A second shaft gear <NUM>' is mounted on a second side which is opposite to a first side of the housing <NUM> on which the motor <NUM> is disposed, and is fixed to the second shaft 50b. The second shaft gear <NUM>' may be rotated by the rotation of the second shaft 50b. The first shaft 50a is may-be- connected or coupled to the second shaft 50b by the joint <NUM> (see <FIG>). <FIG> may be a diagram illustrating connection of the first shaft 50a and the second shaft 50b between <FIG> and <FIG>. The shafts <NUM> may be two or more in number. When the number of the shafts <NUM> increases to n, the number of the joints <NUM> may increase accordingly to n-<NUM>.

The door <NUM> may be opened and closed in such a manner that the first shaft gear <NUM> moves the first slider <NUM> in the forward and backward direction of the housing <NUM>, and the second shaft gear <NUM>' moves the second slider <NUM>' in the forward and backward direction of the housing <NUM>.

Accordingly, the door <NUM> may be opened and closed as the shafts <NUM> rotate without being caught by the holder <NUM> or causing noise and/or vibration.

Claim 1:
A display device comprising:
a flexible display panel (<NUM>);
a roller (<NUM>) on which the display panel (<NUM>) is rolled or unrolled;
a housing (<NUM>) having an opening (30P) through which the display panel (<NUM>) passes, and providing an internal accommodation space, the roller (<NUM>) rotatably mounted in the internal accommodation space; and
a door assembly (<NUM>) mounted in the internal accommodation space at a position adjacent to the opening (30P) of the housing (<NUM>), and opening and closing the opening (30P),
wherein the door assembly (<NUM>) comprises:
a door (<NUM>) for opening and closing the opening (30P);
a motor (<NUM>) for providing power to the door (<NUM>);
a first shaft gear (<NUM>) disposed between the motor (<NUM>) and the door (<NUM>), and transmitting the power, provided by the motor (<NUM>), to the door (<NUM>);
a first shaft (50a) having a first end connected to the first shaft gear (<NUM>), and rotating together with the first shaft gear (<NUM>);
a joint (<NUM>) connected to a second end of the first shaft (50a);
a second shaft (50b) having a first end connected to the joint (<NUM>), and rotating together with the first shaft (50a); and
a second shaft gear (<NUM>') connected to a second end of the second shaft (50b), and transmitting power to the door (<NUM>),
characterized in that
the first shaft (50a) comprises a first joint through hole (<NUM>) formed adjacent to the second end of the first shaft (50a) in a diametral direction of the first shaft (50a), and
the joint (<NUM>) comprises:
a body (<NUM>) which has an elongated cylindrical shape, and into which the second end of the first shaft (50a) with the first joint hole (<NUM>) is inserted; and
a first locking pin (<NUM>) inserted into the first joint hole (<NUM>) in a diametral direction through the body (<NUM>).