Patent Description:
The importance of a display device has steadily increased with the development of multimedia technology. Accordingly, various types of the display device such as a liquid crystal display ("LCD"), an organic light emitting display ("OLED") and the like have been used.

Meanwhile, a mobile electronic device includes a display unit to provide images to a user. The market share of mobile electronic devices having the same or a smaller volume or thickness and a larger display screen than those of the conventional mobile electronic devices has increased. Further, a foldable display device or a bendable display device has also been developed, which has a structure that can be folded and unfolded to provide a larger screen when used only.

<CIT>, <CIT> and <CIT> disclose portable electronic devices comprising a flexible display. The flexible display is folded and unfolded using hinge structure. The hinge structure comprises a four of rotation axes, all four rotation axes being parallel to each other and to the folding axis. The documents further disclose first and second supporting members connected respectively to one side of the hinge structure and rotatable around a first rotation axis and a second rotation axis. <CIT> further discloses first and second hinge pins disposed each on one side of the hinge providing a third and a fourth rotation axis, the hinge structure further comprising a first and a second hinge barrel respectively connected to the first and second hinge pin.

Aspects of the present disclosure provide a display device that is capable of stopping at a certain angle in the course of being folded or unfolded.

However, aspects of the present disclosure are not restricted to the one set forth herein. The above and other aspects of the present disclosure will become more apparent to one of ordinary skill in the art to which the present disclosure pertains by referencing the detailed description of the present disclosure given below. The invention is defined in the appended independent claim <NUM>. Particular embodiments are defined in the dependent claims.

The display device according to various embodiments can stop at a certain angle in the course of being folded or unfolded.

The effects of the present disclosure according to the invention are not limited to the aforementioned effects, and various other effects are included in the present specification.

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. The same reference numbers indicate the same components throughout the specification. In the attached figures, the thickness of layers and regions is exaggerated for clarity.

It will also be understood that when a layer is referred to as being "on" another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms, including "at least one," unless the content clearly indicates otherwise. The exemplary term "lower," can therefore, encompasses both an orientation of "lower" and "upper," depending on the particular orientation of the figure. The exemplary terms "below" or "beneath" can, therefore, encompass both an orientation of above and below.

Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings.

<FIG> is a perspective view of a display device according to an exemplary embodiment. <FIG> is a perspective view illustrating the display device of <FIG> in a folded state. <FIG> is an exploded perspective view of the display device of <FIG>.

In the present disclosure, a first direction DR1, a second direction DR2, and a third direction DR3 cross each other in different directions. The first direction DR1 may be a vertical direction, the second direction DR2 may be a horizontal direction, and the third direction D3 may be a thickness direction with respect to a plan view of the display device. The third direction DR3 may include an upward direction toward the top of <FIG> and a downward direction toward the bottom of <FIG>. One surface of a member that is oriented in the upward direction may be referred to as top surface, and the other surface of the member that is oriented in the downward direction may be referred to as bottom surface. However, the above examples are just relative ones, and the directions are not limited thereto in the following embodiments.

A display device <NUM> according to an exemplary embodiment of the present disclosure may include various devices that display an image on a screen. Examples of the display device <NUM> may include, but are not limited to, a smartphone, a mobile phone, a tablet PC, a personal digital assistant ("PDA"), a portable multimedia player ("PMP"), a television, a game machine, a wristwatch-type electronic device, a head-mounted display, a monitor of a personal computer, a laptop computer, a car navigation system, a car's dashboard, a digital camera, a camcorder, an external billboard, an electronic billboard, various medical devices, various inspection devices, various household appliances such as a refrigerator and a washing machine including a display portion DPA, an Internet-of-Things device, and the like.

With reference to <FIG> and <FIG>, the display device <NUM> may, in a plan view of the unfolded state, have a rectangular shape with two short sides extended in the first direction DR1 and two long sides extended in the second direction DR2. However, the display device <NUM> according to the invention is not limited thereto and may have one of various shapes such as a square, a circle, and a diamond.

The display device <NUM> includes a display surface DS. The display surface DS may provide the user with a screen. At least one surface of the display device <NUM> is the display surface DS. Although the display surface DS of the display device <NUM> may be the top surface of the display device <NUM> in an embodiment, the present disclosure according to the invention is not limited thereto. In some embodiments, the display surface DS of the display device <NUM> may include the side surfaces and/or the bottom surface of the display device <NUM>.

The display surface DS may include a display area DA and a non-display area NDA. The display area DA is configured to display an image. The display area DA may be disposed over a first non-folding area NFA1, a second non-folding area NFA2, and a folding area FA, which will be described later. The non-display area NDA does not display an image. The non-display area NDA may be disposed around the display area DA. In one embodiment, the display area DA may be arranged on the top surface of the display device <NUM> in a rectangular manner, and the non-display area NDA may be arranged to surround the display area DA.

The display device <NUM> may include a folding area FA, a first non-folding area NFA1, and a second non-folding area NFA2. The folding area FA is an area that is folded or bent when the display device <NUM> is folded. The first non-folding area NFA1 and the second non-folding area NFA2 are areas that are not folded or bent even when the display device <NUM> is folded. Although the first non-folding area NFA1, the folding area FA, and the second non-folding area NFA2 may be arranged in order in an embodiment, the present disclosure according to the invention is not limited thereto.

The display device <NUM> may be a foldable device. The display device <NUM> may be folded or unfolded according to a state. Specifically, the display device <NUM> may be folded such that a portion of the display device <NUM> overlaps the other portion or is inclined with respect to the other portion, or the display device <NUM> may be unfolded to be entirely flat. Although one part of the display device <NUM> may be a section arranged in the first non-folding area NFA1 and the other part of the display device <NUM> may be a section arranged in the second non-folding area NFA2, the present disclosure according to the invention is not limited thereto. In another embodiment, the one part and/or the other part of the display device <NUM> may each include a portion arranged in the folding area FA.

The display device <NUM> may be completely folded such that the one and the other parts of the display device <NUM> form an angle of approximately <NUM> degrees (°) or <NUM>°, partly folded such that the one and the other parts of the display device <NUM> form an angle in the approximate range greater than <NUM>° and less than <NUM>°, or unfolded such that the one and the other part of the display device <NUM> form an angle of approximately <NUM>°.

The display device <NUM> may be in-folded. Being in-folded means that the display device <NUM> is folded such that the one part of the display surface DS of the display device <NUM> faces the other part of the display surface DS. In some embodiments, the display device <NUM> may be out-folded. Being out-folded means that the display device <NUM> is folded such that one part of the opposite surface of the display surface DS (e.g., bottom surface of the display device <NUM> opposite to the display surface DS) faces the other part of the opposite surface. The opposite surface may be, for example, the bottom surface of the display device. In some embodiments, the display device <NUM> may be in-folded and/or out-folded.

The display device <NUM> may have a folded state or an unfolded state. The folded state is a state where the display device <NUM> is bent such that one part of the display device <NUM> is inclined with respect to the other part. The folded state may include a first folded state and a second folded state. The first folded state may be a state where the display device <NUM> is partially folded. In the first folded state, the one and the other parts of the display device <NUM> may form an angle in an approximate range greater than <NUM>° and less than <NUM>° or greater than <NUM>° and less than <NUM>°. The second folded state may be a state where the display device <NUM> is completely folded. In the second folded state, the one and the other parts of the display device <NUM> may form an angle of approximately <NUM>° and/or <NUM>°. The unfolded state is a state where the display device <NUM> is completely unfolded such that the one and the other parts of one surface of the display device <NUM> are arranged to be level with each other on one plane (i.e., coplanar). In the unfolded state, the one and the other parts of the display device <NUM> may form an angle of approximately <NUM>°. In one embodiment, the display device <NUM> may freely transition between the folded state and the unfolded state.

As to be described later, during a motion of transitioning between the folded state and the unfolded state, the display device <NUM> may stop the movement of the one part and/or the other part of the display device <NUM> at a certain angle and retain the certain angle. The certain angle may be an angle formed between the one and the other parts of the display device <NUM> in the folded state and/or the unfolded state.

The display device <NUM> may be folded or unfolded with respect to a folding axis FX. In one embodiment, the display device <NUM> may be folded or unfolded with respect to the folding axis FX arranged in the first direction DR1, but the present disclosure according to the invention is not limited thereto.

The folding axis FX may include a plurality of rotation axes RX. Although two rotation axes are depicted as an example in <FIG>, the arrangement and number of the plurality of rotation axes according to the invention are not limited thereto.

As shown in <FIG>, the display device <NUM> includes a display module DM and a folding member FM.

The display module DM is arranged on the display surface DS of the display device <NUM>. The display module DM may have a rectangular shape elongated in the second direction DR2 in the unfolded state. The display module DM may be arranged over the folding member FM (to be described later).

The display module DM has flexibility. The display module DM may be folded or unfolded as the folding member FM is folded or unfolded.

The display module DM may be folded to form a curvature. In detail, the folding area FA of the display module DM may form a curvature as the display device <NUM> is folded. Members constituting the folding member FM (to be described later) and the plurality of rotation axes RX may be arranged symmetrically about the curvature center of the display module DM. A radius of the curvature of the folding area FA may increase as the display device <NUM> is unfolded and decrease as the display device <NUM> is folded. In one embodiment, the display module DM may have a predetermined curvature in the state of being completely folded. As to be described later, the plurality rotation axes RX may be arranged with respect to a predetermined curvature center and/or curvature radius.

The folding member FM is arranged beneath the display module DM. The folding member FM supports the display module DM. The display module DM may be folded or unfolded along with the folding member FM.

The folding member FM includes a first supporting member <NUM>, a second supporting member <NUM>, and a hinge <NUM>. The folding member FM may further include a supporting bracket <NUM>, a hinge cover <NUM>, and a lower cover <NUM>.

The first and second supporting members <NUM> and <NUM> are arranged beneath the display module DM. The first and second supporting members <NUM> and <NUM> may be arranged in order in the second direction DR2 on the bottom surface of the display module DM. The first and second supporting members <NUM> and <NUM> are arranged.

symmetrically about the folding area FA or the folding axis FX. The first supporting member <NUM> may be arranged in the first non-folding area NFA1, and the second supporting member <NUM> may be arranged in the second non-folding area NFA2. The first supporting member <NUM> and/or the second supporting member <NUM> may partly overlap the folding area FA. The first and second supporting members <NUM> and <NUM> may be identical with or different from each other in shape and/or size. In one embodiment, the first and second supporting member <NUM> and <NUM> may have a substantially rectangular shape in a plan view. However, the shape of the first and second supporting member <NUM> and <NUM> according to the invention is not limited thereto.

The hinge <NUM> connects the first and second supporting members <NUM> and <NUM>. The hinge <NUM> may be arranged to overlap the folding axis FX in the thickness direction. The hinge <NUM> may be arranged in the folding area FA. The hinge <NUM> may be arranged across the first non-folding area NFA1, the second non-folding area NFA2, and the folding area FA. There may be a plurality of hinges arranged in the first direction DR1. The hinge <NUM> provides a plurality of rotation axes RX. The first and second supporting members <NUM> and <NUM> are each connected to the hinge <NUM>. In detail, the first supporting member <NUM> is connected to one side of the hinge <NUM> and rotatable with respect to a first rotation axis RX1_1 (See <FIG>), and the second supporting member <NUM> is connected to the other side of the hinge <NUM> and rotatable with respect to a second rotation axis RX1_2 (See <FIG>).

The supporting bracket <NUM> is arranged between the first and second supporting members <NUM> and <NUM>. The supporting bracket <NUM> may be arranged between a plurality of hinges <NUM>. The supporting bracket <NUM> may support a portion of the display module DM arranged between the first and second supporting members <NUM> and <NUM> and/or between the plurality of hinges <NUM>. The supporting bracket <NUM> may define at least one opening.

The hinge cover <NUM> covers one side of the hinge <NUM>. The hinge <NUM> may be placed or fixed onto the hinge cover <NUM>. The top surface of the hinge cover <NUM> may have a shape concave downward to accommodate the hinge <NUM> (See <FIG>).

The lower cover <NUM> may include a first lower cover 500_1 covering the bottom surface of the first supporting member <NUM> and a second lower cover 500_2 covering the bottom surface of the second supporting member <NUM>. The first and second lower covers 500_1 and 500_2 may further cover at least part of the hinge <NUM> and/or hinge cover <NUM>.

<FIG> is a cross-sectional view of a display module of <FIG>. <FIG> is a cross-sectional view of a display panel of <FIG>.

With reference to <FIG> and <FIG>, the display module DM may include a display panel <NUM>, an upper stacked structure <NUM>, and a lower stacked structure <NUM>. In one embodiment, the display panel <NUM> may display an image in a direction toward the upper stacked structure <NUM>. The display panel <NUM>, the upper stacked structure <NUM>, and the lower stacked structure <NUM> may be folded or unfolded as the display device <NUM> is folded or unfolded.

The display panel <NUM> is a panel for displaying a screen or an image. Examples of the display panel <NUM> may include not only a self-luminous display panel such as an organic light emitting display ("OLED") panel, an inorganic electroluminescence ("EL") display panel, a quantum dot ("QED") display panel, a micro-LED display panel, a nano-LED display panel, a plasma display panel ("PDP"), a field emission display ("FED") panel and a cathode ray tube ("CRT") display panel, but also a light receiving display panel such as a liquid crystal display ("LCD") panel and an electrophoretic display ("EPD") panel. Hereinafter, an organic light emitting display panel will be described as an example of the display panel <NUM>, and the organic light emitting display panel applied to the embodiment will be simply referred to as the display panel <NUM> unless special distinction is required. However, the embodiment according to the invention is not limited to the organic light emitting display panel, and other display panels mentioned above or known in the art may be applied within the scope of the same technical ideas.

The display panel <NUM> may further include a touch member. The touch member may be provided as a panel or film separate from the display panel <NUM> and attached onto the display panel <NUM>, but may also be provided in the form of a touch layer inside the display panel <NUM> in another embodiment. In the following embodiment, a case in which the touch member is provided inside the display panel <NUM> and included in the display panel <NUM> is illustrated, but the present disclosure according to the invention is not limited thereto.

Referring to <FIG> and <FIG>, the display panel <NUM> may include a substrate SUB, a circuit driving layer DRL on the substrate SUB, a light emitting layer EML on the circuit driving layer DRL, and an encapsulation layer ENL on the light emitting layer EML, and a touch layer TSL on the encapsulation layer ENL.

The substrate SUB may be a flexible substrate including a flexible polymer material such as polyimide or the like. Accordingly, the display panel <NUM> can be bent, folded or rolled. In some embodiments, the substrate SUB may include a plurality of sub-substrates overlapping in a thickness direction (e.g., the third direction DR3) with a barrier layer interposed therebetween. In this case, each sub-substrate may be a flexible substrate.

The circuit driving layer DRL may be disposed on the substrate SUB. The circuit driving layer DRL may include a circuit that drives the light emitting layer EML of the pixel. The circuit driving layer DRL may include a plurality of thin film transistors.

The light emitting layer EML may be disposed on the circuit driving layer DRL. The light emitting layer EML may include an organic light emitting layer. The light emitting layer EML may emit light with various luminance levels according to a driving signal transmitted from the circuit driving layer DRL.

The encapsulation layer ENL may be disposed on the light emitting layer EML. The encapsulation layer ENL may include an inorganic layer or a laminated layer of an inorganic layer and an organic layer.

The touch layer TSL may be disposed on the encapsulation layer ENL. The touch layer TSL is a layer for recognizing a touch input, and may function as a touch member. The touch layer TSL may include a plurality of sensing areas and sensing electrodes.

With reference to <FIG> again, the upper stacked structure <NUM> is arranged on the top surface of the display panel <NUM>. The upper stacked structure <NUM> may include a polarization member <NUM>, a cover window <NUM>, and a cover window protective layer <NUM> that are stacked in order upward from the display panel <NUM>.

The polarization member <NUM> polarizes the light passing therethrough. The polarization member <NUM> may serve to reduce the reflection of external light. In one embodiment, the polarization member <NUM> may be a polarizing film. The polarizing film may include a polarizing layer and protective substrates sandwiching the polarizing layer therebetween. The polarizing layer may include a polyvinyl alcohol film. The polarizing layer may be stretched in one direction. The stretching direction of the polarizing layer may be an absorption axis, and a direction perpendicular to the stretching direction may be a transmission axis. The protective substrates may be disposed on one surface and the other surface of the polarizing layer, respectively. The protective substrate may be made of cellulose resin such as triacetyl cellulose, polyester resin, or the like, but is not limited thereto.

A cover window <NUM> may be disposed on the polarization member <NUM>. The cover window <NUM> serves to protect the display panel <NUM>. The cover window <NUM> may include or be made of a transparent material. The cover window <NUM> may include, for example, glass or plastic.

When the cover window <NUM> includes glass, the glass may be ultra-thin glass ("UTG") or thin glass. When the glass is ultra-thin glass or thin glass, it may have a flexible property such that it can be bent, folded, or rolled. The thickness of the glass may be, for example, in the range of <NUM> micrometers (µm) to <NUM>, particularly, <NUM> to <NUM> or about <NUM>. The glass of the cover window <NUM> may include soda-lime glass, alkali aluminosilicate glass, borosilicate glass, or lithium alumina silicate glass. The glass of the cover window <NUM> may include chemically strengthened or thermally strengthened glass to have strong rigidity. Chemical strengthening may be achieved through an ion exchange process in alkaline salts. The ion exchange process may be performed two or more times.

If the cover window <NUM> includes plastic, this may serve to improve flexible characteristics such as fordable characteristic. Examples of plastics applicable to the cover window <NUM> may include, but are not limited to, polyimide, polyacrylate, polymethylmethacrylate ("PMMA"), polycarbonate ("PC"), polyethylenenaphthalate ("PEN"), polyvinylidene chloride, polyvinylidene difluoride ("PVDF"), polystyrene, ethylene vinylalcohol copolymer, polyethersulphone ("PES"), polyetherimide ("PEI"), polyphenylene sulfide ("PPS"), polyarylate ("PAR"), triacetyl cellulose ("TAC"), and cellulose acetate propionate ("CAP"). The plastic cover window <NUM> may be formed to include one or more of the plastic materials mentioned above.

The cover window protective layer <NUM> may be disposed on the cover window <NUM>. The cover window protective layer <NUM> may perform at least one of functions of prevention of scattering, impact absorption, prevention of scratch, prevention of fingerprint smudges and prevention of glare on the cover window <NUM>. The cover window protective layer <NUM> may be formed to include a transparent polymer film. The transparent polymer film includes at least one of polyethylene terephthalate ("PET"), polyethylene naphthalate (PEN), polyether sulfone (PES), polyimide ("PI"), polyarylate (PAR), polycarbonate (PC), polymethyl methacrylate (PMMA), or cycloolefin copolymer ("COC").

The upper stacked structure <NUM> may include upper bonding members 25_1, 25_2, and 25_3 for bonding adjacently stacked members. For example, a first bonding member 25_1 may be disposed between the cover window protective layer <NUM> and the cover window <NUM> to bond them, a second bonding member 25_2 may be disposed between the cover window <NUM> and the polarization member <NUM> to bond them. A third bonding member 25_3 may be disposed between the polarization member <NUM> and the display panel <NUM> to bond them. That is, the upper bonding members 25_1, 25_2, and 25_3 may be members that attach the layers to one surface of the display panel <NUM>. The first bonding member 25_1 may be a protective layer bonding member for attaching the cover window protective layer <NUM>, the second bonding member 25_2 may be a window bonding member for attaching the cover window <NUM>, and the third bonding member 25_3 may be a polarizing portion bonding member for attaching the polarization member <NUM>. All of the upper bonding members 25_1, 25_2, and 25_3 may be optically transparent.

The lower stacked structure <NUM> is arranged under the display panel <NUM>. The lower stacked structure <NUM> may include a polymer film layer <NUM> and a heat dissipation member <NUM> stacked in order downward from the display panel <NUM>.

The polymer film layer <NUM> may include a polymer film. The polymer film layer <NUM> may include, for example, polyimide (PI), polyethylene terephthalate (PET), polycarbonate (PC), polyethylene ("PE"), polypropylene ("PP"), polysulfone ("PSF"), polymethylmethacrylate (PMMA), triacetylcellulose (TAC), cycloolefin polymer ("COP") or the like. The polymer film layer <NUM> may include a functional layer on at least one surface thereof. The functional layer may include, for example, a light absorbing layer. The light absorbing layer may include a light absorbing material such as a black pigment or dye. The light absorbing layer may be formed by coating or printing black ink on a polymer film.

The heat dissipation member <NUM> may be disposed under the polymer film layer <NUM>. The heat dissipation member <NUM> serves to diffuse heat generated from the display panel <NUM> or other components of the display device <NUM>. The heat dissipation member <NUM> may be a heat dissipation sheet including graphite, carbon nanotubes or the like. In one embodiment, the heat dissipation members <NUM> may be separated by the folding area FA to facilitate folding of the display device <NUM> as illustrated in <FIG> and <FIG>. In some embodiments, the heat dissipation members <NUM> may be connected as one body.

The lower stacked structure <NUM> may include lower bonding members 35_1 and 35_2 for bonding adjacently stacked members. For example, a fourth bonding member 35_1 may be disposed between the display panel <NUM> and the polymer film layer <NUM> to bond them, and a fifth bonding member 35_2 may be disposed between the polymer film layer <NUM> and the heat dissipation member <NUM> to bond them.

In some embodiments, the lower stacked structure <NUM> may further include a buffer member. The buffer member may be disposed, for example, between the polymer film layer <NUM> and the heat dissipation member <NUM>.

<FIG> is a perspective view of a hinge of <FIG>. <FIG> is an exploded perspective view of the hinge of <FIG>. <FIG> is a perspective view of the hinge of <FIG> with exclusion of a rotor bracket and a connection bracket.

With reference to <FIG> and <FIG>, the hinge <NUM> includes a base frame <NUM>, a hinge barrel <NUM>, and a hinge pin <NUM>. The hinge <NUM> may further include a plurality of cams <NUM>, a rotor bracket <NUM>, and a connection bracket <NUM>.

The base frame <NUM> may have a rod shape elongated in the first direction DR1 in a plan view. The top surface of the base frame <NUM> includes a plurality of indented parts for receipt and/or engagement with other members. The top surface and/or bottom surface of the base frame <NUM> may have a curvature convex downward. The base frame <NUM> may receive a first hinge barrel 240_1, a second hinge barrel 240_2, a first hinge pin 250_1, a second hinge pin 250_2, a plurality of cams <NUM>, and/or the rotor bracket <NUM>. The base frame <NUM> may include at least one groove and/or at least one guide surface for guiding the plurality of cams <NUM>. The at least one guide surface may be at least part of the top surface of the base frame <NUM>.

The hinge barrel <NUM> includes the first hinge barrel 240_1 and the second hinge barrel 240_2. A pair of the first hinge barrel 240_1 and the second hinge barrel 240_2 is arranged at one side of the base frame <NUM>, and another pair of first hinge barrel 240_1 and the second hinge barrel 240_2 is arranged at the other side of the base frame <NUM>. In detail, the first hinge barrel 240_1 may be arranged at one side of the base frame <NUM> close to the first supporting member <NUM>, and the second hinge barrel 240_2 may be arranged at the other side of the base frame <NUM> close to the second supporting member <NUM>. With reference to <FIG>, <FIG>, and <FIG>, the first and second hinge barrels 240_1 and 240_2 are arranged symmetrically with respect to the base frame <NUM>. The first and second hinge barrels 240_1 and 240_2 may be arranged to rotate in opposite directions. The first and second hinge barrels 240_1 and 240_2 are engaged to rotate about the first and second hinge pins 250_1 and 250_2 (to be described later) with respect to the base frame <NUM>, respectively. It may also be possible that a plurality of first and second hinge barrels 240_1 and 240_2 is arranged. In one embodiment, two first hinge barrels 240_1 may be arranged at one side of the base frame <NUM>, and two second hinge barrels 240_2 may be arranged at the other side of the base frame <NUM>. Although the first and second hinge barrels 240_1 and 240_2 may each have a shape of a cuboid block with an indentation in an embodiment, the present disclosure according to the invention is not limited thereto.

The hinge pin <NUM> includes the first hinge pin 250_1 and the second hinge pin 250_2. The first and second hinge pins 250_1 and 250_2 are inserted into the first and second hinge barrels 240_1 and 240_2, respectively. The first and second hinge pins 250_1 and 250_2 may be placed and fixed on the top surface of the base frame <NUM>. In detail, the first and second hinge pins 250_1 and 250_2 may be received into parts of the base frame <NUM>, recessed downward by a predetermined depth from the top surface thereof. It may also be possible that a plurality of first and second hinge pins 250_1 and 250_2 is arranged. In one embodiment, two first hinge pins 250_1 are arranged at one side of the base frame <NUM>, and two second hinge pins 250_2 are arranged at the other side of the base frame <NUM>.

The plurality of cams <NUM> are placed on the top surface of the base frame <NUM>. In detail, the plurality of cams <NUM> may be slidably placed in parts of the base frame <NUM>, recessed downward from the top surface thereof to allow rotational and/or linear motions of the respective cams <NUM>. The plurality of cams <NUM> may each have a semi-circular cross-section. In one embodiment, the bottom surfaces of the plurality of cams <NUM> may include convex surfaces, respective, the top surface of the base frame <NUM> may include concave surfaces corresponding to the convex surfaces, and the rotational and/or linear motions of the plurality of cams <NUM> may be guided by the convex and concave surfaces.

The plurality of cams <NUM> may include a first rotor cam <NUM>, a second rotor cam <NUM>, and a slide cam <NUM>.

The first and second rotor cams <NUM> and <NUM> may connect to first and second connection brackets 260_1 and 260_2 (to be described later), respectively. The first and second rotor cams <NUM> and <NUM> may have convex surfaces facing the top surface of the base frame <NUM> and flat surfaces connecting one and the other ends of the convex surfaces at the upper parts thereof. In one embodiment, the first and second rotor cams <NUM> and <NUM> may include at least one connection protrusion 221_1 and 222_1 protruded upward from the flat surface thereof, respectively. The connection protrusion 221_1 of the first rotor cam <NUM> is engaged with the rotor connection hole 261_1 of the first connection bracket 260_1, and the connection protrusion 222_1 of the second rotor cam <NUM> may be engaged with the rotor connection hole 261_2 of the second connection bracket 260_2.

The slide cam <NUM> is arranged between the first and second rotor cams <NUM> and <NUM>. The slide cam <NUM> may be arranged on the top surface of the base frame <NUM> and include a guide hole 223_1 engaged with a guide bump 210_BP protruded upward.

In one embodiment, the first rotor cam <NUM>, the second rotor cam <NUM>, and the slide cam <NUM> may each be a negative end cam. In the case where the display device <NUM> is folded or unfolded, the first rotor cam <NUM> may perform a rotational motion in a first rotation direction, the second rotor cam <NUM> may perform a rotational motion in a second rotation direction, and the slide cam <NUM> may perform a linear motion in the first direction DR1. Here, the first rotation direction and the second rotation direction are opposite rotational directions from each other. The slide cam <NUM> may transfer the rotation of the first rotor cam <NUM> to the second rotor cam <NUM> and transfer the rotation of the second rotor cam <NUM> to the first rotor cam <NUM> such that the first and second supporting members <NUM> and <NUM> are evenly folded or unfolded.

The rotor bracket <NUM> covers at least part of the plurality of cams <NUM>. In one embodiment, the rotor bracket <NUM> may cover the slide cam <NUM> in whole and the first and second rotor cams <NUM> and <NUM> in part. The rotor bracket <NUM> may guide the rotational motion and/or linear motion of the plurality of cams <NUM>.

The connection bracket <NUM> may include the first connection bracket 260_1 and the second connection bracket 260_2. The first and second connection brackets 260_1 and 260_2 are arranged symmetrically with respect to the base frame <NUM> and/or the folding axis FX. The first connection bracket 260_1 may be arranged at one side of the base frame <NUM>, and the second connection bracket 260_2 may be arranged at the other side of the base frame <NUM>. The first connection bracket 260_1 may connect the first rotor cam <NUM> and the first supporting member <NUM>, and the second connection bracket 260_2 may connect the second rotor cam <NUM> and the second supporting member <NUM>. The first and second connection brackets 260_1 and 260_2 may rotate in opposite directions. The first and second connection brackets 260_1 and 260_2 may be arranged to cover at least one of the base frame <NUM>, the plurality of cams <NUM>, the rotor bracket <NUM>, the first hinge pin 250_1, and the second hinge pin 250_2. The first and second connection brackets 260_1 and 260_2 may expose at least part of the first and second hinge barrels 240_1 and 240_2, respectively. Although the first and second connection brackets 260_1 and 260_2 may have a cuboid shape elongated in the first direction DR1 in an embodiment, the present disclosure according to the invention is not limited thereto.

Hereinafter, detailed descriptions are made regarding the first and second hinge barrels 240_1 and 240_2 and the first and second hinge pins 250_1 and 250_2 with reference to <FIG> and <FIG>.

<FIG> is an exploded perspective view of first and second hinge barrels and first and second hinge pins of <FIG>.

With reference to <FIG> and <FIG>, the first and second hinge barrels 240_1 and 240_2 may include respective body parts 241_1 and 241_2, respective barrel parts 242_1 and 242_2, and respective sliding poles 244_1 and 244_2. The first and second hinge barrels 240_1 and 240_2 may further include respective connection parts 243_1 and 243_2, respective hinge cover-receiving grooves 245_1 and 245_2, and respective stepped parts 246_1 and 246_2.

The first and second hinge barrels 240_1 and 240_2 may be substantially identical with or similar to each other in structure. Hereinafter, the description is mainly directed to the first hinge barrel 240_1 as an example.

The body part 241_1 constitutes the body of the first hinge barrel 240_1. At least part of the body part 241_1 may be slidably inserted into the hinge barrel receiving part 263_1 of the first connection bracket 260_1. The insertion depth of the body part 241_1 inside the hinge barrel receiving part 263_1 may vary according to an angle between the first and second supporting members <NUM> and <NUM> (See <FIG>). The body part 241_1 may include a pair of branches split off in the direction toward the first supporting member <NUM>. A pair of sliding poles 244_1 may be arranged for the pair of branches, respectively. The body part 241_1 may have a recess portion recessed toward the base frame <NUM> between the paired branches to receive a guide wall GL (See <FIG>) of the hinge barrel receiving part 263_1 of the first connection bracket 260_1 (to be described later).

The barrel part 242_1 is arranged, close to the base frame <NUM>, at one side of the body part 241_1. The first hinge pin 250_1 is inserted into the barrel part 242_1. In one embodiment, a plurality of barrel parts 242_1 may be arranged in the first direction DR1. In some embodiments, one barrel part 242_1 may be arranged. Hereinafter, detailed description is made regarding the barrel part 242_1 with reference to <FIG>.

The sliding pole 244_1 may be arranged to protrude from the body part 241_1. In detail, the sliding poles 244_1 may be composed of two paired parts that are arranged at one and the other sides of the body part 241_1. The sliding pole 244_1 may be slidably received in the hinge barrel receiving part 263_1 of the first connection bracket 260_1 (to be described later). A part of the sliding pole 244_1 that contacts the first connection bracket 260_1 may have a curved surface. For example, the sliding pole 244_1 may have a cylindrical shape. Accordingly, the first hinge barrel 240_1 may be arranged to be inclined with respect to the first connection bracket 260_1 when the display device <NUM> is folded or unfolded, as to be described with reference to <FIG>. In some embodiments, the first hinge barrel 240_1 may be arranged in parallel with the first connection bracket 260_1 when the display device <NUM> is folded or unfolded.

The connection part 243_1 connects one side of the body part 241_1 and one side of the barrel part 242_1. The thickness of the connection part 243_1 may be less than each of the thickness of the body part 241_1 and the barrel part 242_1.

The hinge cover-receiving groove 245_1 is provided beneath the connection part 243_1. The hinge cover-receiving groove 245_1 may be defined to be recessed upward. The hinge cover-receiving groove 245_1 may prevent the hinge cover <NUM> and the first hinge barrel 240_1 from interfering with each other during the folding or unfolding motion of the display device <NUM>.

The stepped part 246_1 is provided on top of the body part 241_1. The stepped part 246_1 may be slidably received in the upper recess 263_G_1 of the first connection bracket 260_1 (to be described later). The insertion depth of the first hinge barrel 240_1 inside the hinge barrel receiving part 263_1 may be limited depending on the condition whether the stepped part 246_1 contacts or is separated from a part of the first connection bracket 260_1 that defines the upper recess 263_G_1.

The first and second hinge pins 250_1 and 250_2 include respective cylindrical parts 251_1 and 251_2, respective head parts 252_1 and 252_2, and respective tail parts 253_1 and 253_2. The first and second hinge pins 250_1 and 250_2 may further include respective locking parts 254_1 and 254_2 and respective oil grooves 255_1 and 255_2.

The first and second hinge pins 250_1 and 250_2 may be substantially identical with or similar to each other in structure. Hereinafter, the description is mainly directed to the first hinge pin 250_1.

The first cylindrical part 251_1 is arranged in the first direction DR1. The cylindrical part 251_1 provides a rotation axis in the first direction DR1. At least part of the cylindrical part 251_1 is inserted into the barrel part 242_1 of the first hinge barrel 240_1.

The head part 252_1 is arranged at one end of the cylindrical part 251_1. The head part 252_1 may have a flat rectangular parallelepiped shape. The head part 252_1 may define a first connection hole H1.

The tail part 253_1 is arranged at the other end of the cylindrical part 251_1. The tail part 253_1 may penetrate the barrel part 242_1. The tail part 253_1 may be smaller in size than the head part 252_1. The tail part 253_1 may have a wedge shape, by way of example, tapering in width toward one end. The tail part 253_1 may define a second connection hole H2.

The locking part 254_1 is arranged between the head part 252_1 and the cylindrical part 251_1. The locking part 254_1 may limit the insertion depth of the first hinge pin 250_1 inside the barrel part 242_1. The locking part 254_1 may be greater in radius than each of the head part 252_1, the tail part 253_1, and the cylindrical part 251_1. The locking part 254_1 may have a radius greater than that of the curvature of a concave surface formed by a first curvature part 242_1_1 and a second curvature part 242_1_2 of the barrel part 242_1 (to be described later).

The oil groove 255_1 may be defined in a circumferential direction on the outer circumferential surface of the cylindrical part 251_1 in a recessed manner. A plurality of oil grooves 255_1 may be defined on the outer circumferential surface of the cylindrical part 251_1.

Hereinafter, detailed descriptions are made of the shape of the barrel part 242_1 and the connection relationship between the first hinge barrel 240_1 and the first hinge pin 250_1.

<FIG> show a cross-sectional view and plan views of a first hinge barrel of <FIG>.

<FIG> is a cross-sectional view of the first hinge barrel 240_1 taken along line B-B'. <FIG> is a plan view of the first hinge barrel 240_1. <FIG> is a plan view of the first hinge barrel 240_1 according to another embodiment.

With reference to <FIG> and <FIG>, one side of the barrel part 242_1 may be connected to the connection part 243_1. The other end of the barrel part 242_1 opposite to the one end of the barrel part 242_1 may be hollowed with respect to the curvature center of the barrel part 242_1 or the first hinge pin 250_1. In detail, at one side of the barrel part 242_1, a slit or an opening is defined to extend in a direction of insertion (i.e., the first direction DR1) of the first hinge pin 250_1. Accordingly, the barrel part 242_1 may have a C-shaped cross-section.

The barrel part 242_1 may include the first curvature part 242_1_1 and the second curvature part 242_1_2.

The first and second curvature parts 242_1_1 and 242_1_2 may each have a predetermined width in the first direction DR1 to surround at least part of the outer circumferential surface of the cylindrical part 251_1. The surfaces of the first and second curvature parts 242_1_1 and 242_1_2 that face the cylindrical part 251_1 of the first hinge pin 250_1 may be connected to each other to form a concave surface contacting at least part of the outer circumferential surface of the cylindrical part 251_1. The first and second curvature parts 242_1_1 and 242_1_2 may each be connected, at one side thereof, to the connection part 243_1, and may be separated, at the other sides thereof, by a predetermined distance. Accordingly, a slit-shaped opening BR_OP extending in the first direction DR1 may be defined at one side of the barrel part 242_1. In cross-sectional view (See <FIG>), the hollow of the barrel part 242_1 may communicate with the outside through the opening BR_OP such that part of the outer circumferential surface of the first hinge pin 250_1 inserted into the barrel part 242_1 is exposed to the outside.

The first hinge pin 250_1 may be inserted into the barrel part 242_1 of the first hinge barrel 240_1 in an interference fit manner. In detail, the first hinge pin 250_1 may be greater in radius than the first hinge barrel 240_1. Accordingly, in the case where the first hinge pin 250_1 is inserted into the first hinge barrel 240_1 in a press-fit manner, the barrel part 242_1 of the first hinge barrel 240_1 may be elastically deformed, and a restoration force P caused by the elastic deformation may produce a predetermined friction force between the cylindrical part 251_1 of the first hinge pin 250_1 and the barrel part 242_1 of the first hinge barrel 240_1. The predetermined friction force may produce a friction torque when the display device <NUM> is folded or unfolded. The size of the torque for folding or unfolding the display device <NUM> may be determined by the friction torque. That is, the display device <NUM> may stop the folding or unfolding motion thereof at a certain angle, and retain the certain angle. In one embodiment, the first hinge barrel 240_1 and the first hinge pin 250_1 may be made of a metal material, and the surfaces of the barrel part 242_1 and the cylindrical part 251_1 may be heat-treated to improve the hardness and wear resistance.

With reference to <FIG> and <FIG>, the friction torque may be determined by at least one of the thickness of the first curvature part 242_1_1, the thickness of the second curvature part 242_1_2, widths B1 and B2 of the barrel part 242_1, a radius r of the barrel part 242_1, a difference between the radius of the barrel part 242_1 before insertion of the cylindrical part 251_1 and the radius of the cylindrical part 251_1, or an angle α at which the opening BR_OP is defined with respective to the center of the curvature of the barrel part 242_1 or cylindrical part 251_1.

With reference to <FIG>, a plurality of barrel parts 242_1 may be arranged to adjust the total width of the barrel parts 242_1 through which the cylindrical part 251_1 is inserted. The total width of the barrel parts 242_1 may be the sum of the first width B1 of one side barrel part 242_1 and the second width B2 of the other side barrel part 242_1. That is, the barrel parts 242_1 may define a recessed portion that makes it possible to adjust the total width of the barrel parts 242_1, leading to adjustment of the amount of friction torque. The first and second widths B1 and B2 may be equal or unequal to each other.

With reference to <FIG>, one barrel part 242_1 may be provided unlike the embodiment of <FIG>. The barrel part 242_1 according to the embodiment of <FIG> may produce a friction torque greater than that of the barrel part_242_1 of the embodiment of <FIG> because a width B3 of the barrel part 242_1 is wider than a sum of the widths B1 and B2 of the barrel part 242_1 in <FIG>,.

Hereinafter, detailed descriptions are made of the first and second connection brackets 260_1 and 260_2 with reference to <FIG> and <FIG>.

<FIG> is a perspective cross-sectional view taken along line A-A' of <FIG>. <FIG> is an enlarged perspective view of a hinge barrel receiving part of a first connection bracket of <FIG>.

With reference to <FIG>, <FIG>, and <FIG>, the first and second connection brackets 260_1 and 260_2 may include base plates BT_1 and BT_2, the rotor connection holes 261_1 and 261_2, supporting member connection holes 262_1 and 262_2, and the hinge barrel receiving parts 263_1 and 263_2, respectively.

Because the first and second connection brackets 260_1 and 260_2 are substantially identical with or similar to each other, the description is mainly directed to the first connection bracket 260_1.

The base plate BT_1 may have, but is not limited to, a rectangular shape in a plan view.

The rotor connection holes 261_1 is defined to penetrate the base plate BT_1. The rotor connection hole 261_1 of the first connection bracket 260_1 may receive the connection protrusion 221_1 of the first rotor cam <NUM>, and the rotor connection hole 261_2 of the second connection bracket 260_2 may receive the connection protrusion 222_1 of the second rotor cam <NUM>.

The supporting member connection hole 262_1 is defined to penetrate the base plate BT_1. Although not shown in the drawings, the supporting member connection hole 262_1 of the first connection bracket 260_1 may receive a connection member such as a bolt for connection to the first supporting member <NUM>, and the supporting member connection hole 262_2 of the second connection bracket 260_2 may receive a connection member such as a bolt for connection to the second supporting member <NUM>.

The hinge barrel receiving part 263_1 is arranged beneath the base plate BT_1. The hinge barrel receiving part 263_1 may slidably receive at least part of the first hinge barrel 240_1 in a pocket-shaped inner space.

The hinge barrel receiving part 263_1 may include the upper recess 263_G_1, a lower recess 263_G_2, and a slot S_1.

The upper recess 263_G_1 is arranged at the upper part of the hinge barrel receiving part 263_1. The upper recess 263_G_1 may be defined to be recessed in a direction from a side edge, close to the base frame <NUM>, of the base plate BT_1 to the other edge at which the first supporting member <NUM> is arranged. The upper recess 263_G_1 may receive the upper part of the first hinge barrel 240_1. In detail, the upper recess 263_G_1 may receive the stepped part 246_1 of the first hinge barrel 240_1. The stepped part 246_1 of the first hinge barrel 240_1 may be caught in the upper recess 263_G_1 to limit the insertion depth of the first hinge barrel 240_1.

The lower recess 263_G_2 is arranged at the lower part of the hinge barrel receiving part 263_1. The lower recess 263_G_2 may be defined to recessed in a direction from a side edge, close to the base frame <NUM>, of the lower part of the hinge barrel receiving part 263_1 to the other side at which the first supporting member <NUM> is arranged. The lower recess 263_G_2 may prevent any interference between the first hinge barrel 240_1 and the lower part of the hinge barrel receiving part 263_1 while the display device <NUM> is folded or unfolded.

The slot S_1 is arranged toward the base frame <NUM>. The slot S_1 may slidably receive at least part of the first hinge barrel 240_1. The sliding pole 244_1 of the first hinge barrel 240_1 may slide between a top surface GS1_1 and a bottom surface GS2_1 of the slot S_1 extending in the second direction DR2 as the display device <NUM> is folded or unfolded. In one embodiment, the slot S_1 may be arranged between the upper recess 263_G_1 and the lower recess 263_G_2 in <FIG> and <FIG>.

The first and second hinge barrels 240_1 and 240_2 and the first and second rotor cams <NUM> and <NUM> may rotate about the plurality of rotation axes RX when the display device <NUM> is folded or unfolded.

Hereinafter, detailed descriptions are made of the plurality of rotation axes RX and rotations of the members about the rotation axes RX with reference to <FIG>.

<FIG> is a cross-sectional view taken along line A-A' of <FIG> in an unfolded state of the display device. <FIG> is a cross-sectional view taken along line A-A' of <FIG> in a first folded state of the display device. <FIG> is a cross-sectional view taken along line A-A' of <FIG> in a second folded state of the display device.

With reference to <FIG> and <FIG>, the hinge <NUM> may provide the plurality of rotation axes RX as described above.

The plurality of rotation axes RX may include the first rotation axis RX1_1, the second rotation axis RX1_2, a third rotation axis RX2_1, and a fourth rotation axis RX2_2.

The first rotation axis RX1_1, the second rotation axis RX1_2, the third rotation axis RX2_1, and the fourth rotation axis RX2_2 extend in parallel in the first direction DR1. In one embodiment, the first and second rotation axes RX1_1 and RX1_2 may be provided by the first and second rotor cams <NUM> and <NUM>, respectively, and the third and fourth rotation axes RX2_1 and RX2_2 may be provided by the first and second hinge pins 250_1 and 250_2, respectively.

The first and second rotation axes RX1_1 and RX1_2 may be arranged symmetrically about the center of the hinge <NUM> in a plan view. Likewise, the third and fourth rotation axes RX2_1 and RX2_2 may be arranged symmetrically about the center of the hinge <NUM> in a plan view. That is, the first and second rotation axes RX1_1 and RX1_2 and the third and fourth rotation axes RX2_1 and RX2_2 may be arranged symmetrically about a virtual center line CL passing through the center of the hinge <NUM> in cross-sectional view, as shown in <FIG>.

The distance between the first and second rotation axes RX1_1 and RX1_2 may be less than the distance between the third and fourth rotation axes RX2_1 and RX2_2. The distance between the first and third rotation axes RX1_1 and RX2_1 and the distance between the second and fourth rotation axes RX2 and RX4 may be equal to each other.

The first supporting member <NUM> rotates about the first rotation axis RX1_1, and the second supporting member <NUM> rotates about the second rotation axis RX1_2. In detail, the first supporting member <NUM> may rotate along with the first rotor cam <NUM> rotating about the first rotation axis RX1_1, and the second supporting member <NUM> may rotate along with the second rotor cam <NUM> rotating about the second rotation axis RX1_2. As described above, the first and second supporting members <NUM> and <NUM> may rotate in opposite directions. For example, the first supporting member <NUM> may rotate in the clockwise direction and the second supporting member <NUM> may rotate in the counterclockwise direction when the display device <NUM> is folded.

The first hinge barrel 240_1 rotates about the third rotation axis RX2_1, and the second hinge barrel 240_2 rotates about the fourth rotation axis RX2_2. The first and second hinge barrels 240_1 and 240_2 may rotate in opposite directions. The first and second hinge barrels 240_1 and 240_2 may rotate along with the first rotor cam <NUM> (the first supporting member <NUM>) and the second rotor cam <NUM> (the second supporting member <NUM>), respectively. For example, the first hinge barrel 240_1 may rotate in the clockwise direction and the second hinge barrel 240_2 may rotate in the counterclockwise direction when the display device is folded.

The insertion depth of the hinge barrel receiving part 263_1 of the first connection bracket 260_1 of the first hinge barrel 240_1 and the insertion depth of the hinge barrel receiving part 263_2 of the second hinge barrel 240_2 may vary according to the angle between the first and second supporting members <NUM> and <NUM>. In detail, as the angle between the first and second supporting members <NUM> and <NUM> decreases, the distance between the end of the first hinge barrel 240_1 received in the hinge barrel receiving part 263_1 of the first hinge barrel 240_1 and the inner wall of the hinge barrel receiving part 263_1 facing the end and the distance between the end of the second hinge barrel 240_2 received in the hinge barrel receiving part 263_2 of the second hinge barrel 240_2 and the inner wall of the second connection bracket 260_2 facing the end may increase. The angle between the first and second supporting members <NUM> and <NUM> may be an angle between the top surface of the first supporting member <NUM> and the top surface of the second supporting member <NUM>. Depending on the arrangement of the plurality of rotation axes RX, the first and second hinge barrels 240_1 and 240_2 may be arranged to be inclined with respect to the first and second connection brackets 260_1 and 260_2, respectively, when the display device <NUM> is in the first folded state.

With reference to <FIG> and <FIG>, the display device <NUM> may stop at a certain angle in the course of being folded or unfolded. The certain angle may be an angle between the first and second hinge barrels 240_1 and 240_2, an angle between the first and second connection brackets 260_1 and 260_2, an angle between the first and second supporting members <NUM> and <NUM>, and/or an angle between the first and second non-folding areas NFA1 and NFA2. In detail, the display device <NUM> may retain the certain angle unless the external force or torque applied to the display device <NUM> is greater than a predetermined force or torque. The predetermined torque may be a friction toque produced by the friction force between the first hinge pin 250_1 and the first hinge barrel 240_1 and the friction force between the second hinge pin 250_2 and the second hinge barrel 240_2. The angle between the first and second hinge barrels 240_1 and 240_2, the angle between the first and second connection brackets 260_1 and 260_2, the angle between the first and second supporting members <NUM> and <NUM>, and/or the angle between the first and second non-folding areas NFA1 and NFA2 are substantially identical with one another.

For example, as shown in <FIG>, the display device <NUM> may maintain the angle between the first and second connection brackets 260_1 and 260_2 or between the first and second hinge barrels 240_1 and 240_2 at approximately <NUM>°. In the case where a torque equal to or greater than a predetermined level is applied, the display device <NUM> may be folded such that the first and second connection brackets 260_1 and 260_2 forms an angle in the approximate range greater than <NUM>° and less than <NUM>°, e.g., approximately <NUM>°, <NUM>°, or <NUM>°. Afterward, if it does not continue to apply the torque greater than the predetermined level, the angle between first and second connection brackets 260_1 and 260_2 may remain constantly. If it continues to apply the torque greater than the predetermined level, the display device <NUM> may be completely folded such that the first and second connection brackets 260_1 and 260_2 forms an angle of approximately <NUM>° or <NUM>°. Afterward, if it does not continue to apply the torque greater than the predetermined level, the display device <NUM> may remain in the completely folded state. That is, the display device <NUM> may continue being folded/unfolded by a torque equal to or greater than the predetermined level, changing the angle between the first and second supporting members <NUM> and <NUM>, and it may stop being folded/unfolded by a torque less than the predetermined level, maintaining the angle between the first and second supporting members <NUM> and <NUM>.

<FIG> is a cross-sectional view showing a locational relationship of rotation axes of <FIG>. <FIG> is a cross-sectional view of a display module and first and second rotation axes of <FIG>.

In <FIG>, other components are omitted with the exception of the display module for convenience of explanation.

With reference to <FIG>, the first and second rotation axes RX1_1 and RX1_2 may be arranged outside the hinge <NUM>. The third and fourth rotation axes RX2_1 and RX2_2 may be arranged to pass through the inside of the hinge <NUM>. In one embodiment, the first and second rotation axes RX1_1 and RX1_2 may be arranged in the display module DM, and the third and fourth rotation axes RX2_1 and RX2_2 may be arranged below the display module DM in a cross-sectional view. In detail, the first and second rotation axes RX1_1 and RX1_2 may be arranged on the top surface or bottom surface of the display module DM, or inside the display module DM.

The first and second rotation axes RX1_1 and RX1_2 may be arranged to have a first distance from a curvature center CC of the display panel <NUM>, and the third and fourth rotation axes RX2_1 and RX2_2 may be arranged to have a second distance from the curvature center CC of the display panel <NUM>. In one embodiment, the curvature center CC may not be arranged at the intersection of a first reference line RL1 and a second reference line RL2 (to be described later). In some embodiments, the curvature center CC may be arranged at the intersection of the first and second reference lines RL1 and RL2 (to be described later). As described above, the curvature center CC of the display panel <NUM> may be a curvature center of a portion of the display module DM arranged at the folding area FA to be folded or unfolded as the display device <NUM> is folded or unfolded. The curvature center CC of the display panel <NUM> may overlap the center of the hinge <NUM> in the thickness direction. In one embodiment, the first distance may be equal to or less than the second distance. In one embodiment, the first distance may be the curvature radius R of the display panel <NUM>. The curvature radius R may be a distance between the top surfaces or bottom surfaces of one and the other parts of the display panel <NUM> that are arranged to face each other when the display panel <NUM> is folded.

With reference to <FIG>, the first and second rotation axes RX1_1 and RX1_2 may be arranged on the first and second reference lines RL1 and RL2 respectively. In detail, it may be possible to define the center line CL that is, when the display device <NUM> is unfolded, perpendicular to the top surface or the bottom surface of the display panel <NUM> and passing through the curvature center CC of the display panel <NUM>. It may also be possible to define a first reference point RP1 and a second reference point RP2 separated by the curvature radius R of the display panel <NUM> from the center line CL in the second direction DR2 on the top surface of the display panel <NUM>. The first and second reference lines RL1 and RL2 may pass through the first and second reference points RP1 and RP2 respectively and each form an angle of <NUM>° with the center line CL. In detail, as shown in <FIG>, the first reference line RL1 may be arranged to form an angel of approximately <NUM>° with the center line CL in the clockwise direction, and the second reference line RL2 may be arranged to form an angle of approximately <NUM>° with the center line CL in the counterclockwise direction. That is, the first and second reference lines RL1 and RL2 may be arranged to cross each other at a right angle. The first and second rotation axes RX1_1 and RX1_2 may be arranged at parts of the first and second reference lines RL1 and RL <NUM>, respectively, overlapping the display module DM in cross-sectional view. The parts of the first and second reference lines RL1 and RL2 may include a point at which the stress applied to the display module DM is minimized, e.g. at least one point on a neutral surface NS or close to the neutral surface NS.

Claim 1:
A display device (<NUM>) comprising:
a display module (DM) including a first surface (DS) which displays an image and a second surface opposite to the first surface (DS);
a hinge (<NUM>) disposed on the second surface of the display module (DM) and providing a plurality of rotation axes (RX) in a first direction (DR1);
a first supporting member (<NUM>) connected to a first side of the hinge (<NUM>) and rotatable with respect to a first rotation axis (RX1_1) of the plurality of rotation axes (RX); and
a second supporting member (<NUM>) connected to a second side of the hinge (<NUM>) and rotatable with respect to a second rotation axis (RX1_2) of the plurality of rotation axes (RX), the second side being opposite the first side,
wherein the hinge (<NUM>) includes:
a base frame (<NUM>);
a first hinge pin (250_1) disposed on a first side of the base frame (<NUM>) and providing a third rotation axis (RX1_3) of the plurality of rotation axes (RX);
a second hinge pin (250_2) disposed on a second side of the base frame (<NUM>) and providing a fourth rotation axis (RX1_4) of the plurality of rotation axes (RX), the second side of the base frame (<NUM>) being opposite the first side of the base frame (<NUM>);
a first hinge barrel (240_1) rotatably coupled to the first hinge pin (250_1); and
a second hinge barrel (240_2) rotatably coupled to the second hinge pin (250_2),
characterized in that
each of the first hinge pin (250_1) and the second hinge pin (250_2) includes a cylindrical part (251_1), a head part (252_1) disposed on a first end of the cylindrical part (251_1), a tail part disposed on a second end of the cylindrical part (251_1), and a locking part (254_1) between the cylindrical part (251_1) and the head part (252_1).