Patent Description:
A display device is a device having a function of receiving, processing, and displaying a video that a user may watch. For example, the display device receives a broadcast selected by the user from broadcast signals transmitted from a broadcasting station, separates a video signal from the received signals, and displays the separated video signal on a display.

In recent years, because of a development of a broadcasting technology and a network technology, functions of the display device have also been considerably diversified, and a performance of the device has been improved accordingly. That is, the display device has been developed to provide not only broadcast contents but also various other contents to the user. For example, the display device may provide game play, music listening, internet shopping, user customized information, and the like using various applications as well as programs received from the broadcasting station. In order to perform such extended functions, the display device may be basically connected to other devices or networks using various communication protocols, and may provide the user with a ubiquitous computing environment. In other words, the display device has evolved into a smart device that enables connectivity to a network and continuous computing.

In one example, recently, the mobile terminal is providing a larger screen to the user. The mobile terminal may provide a large screen that is folded in one direction as a foldable mobile terminal or provide a large screen that is expanded or contracted in one direction as a rollable mobile terminal.

<CIT>, <CIT> and <CIT> are related prior art documents.

The present disclosure relates to a mobile terminal capable of expanding a screen exposed from a front face thereof using a roller, and has an object of preventing a wrinkle of a flexible display panel outputting the screen.

The invention is specified by the independent claim <NUM>. One aspect of the present disclosure proposes a mobile terminal including a first frame, a second frame including a third rear portion disposed on a rear face of the first frame and coupled to the rear face of the first frame in a manner of being movable in a first direction, and a first roller disposed at an end in the first direction of the third rear portion, a third frame disposed on a rear face of the third rear portion and coupled to the rear face of the third rear portion in a manner of being movable in the first direction, a flexible display panel disposed to surround the first roller and having one end disposed on a front face of the first frame and the other end disposed on the third frame, a driving unit for driving the second frame from the first frame in the first direction or in a reverse direction of the first direction, and a spring member for providing a constant force in the reverse direction of the first direction to the third frame.

The spring member includes a fixed shaft, and a spiral spring disposed to be wound around or unwound from the fixed shaft, wherein the spiral spring generates a constant attractive force while being wound around or unwound from the fixed shaft.

In one implementation, when the spiral spring provides the constant attractive force in a state of being unwound by a length equal to or greater than a first length, the spring member may connect the third frame and the third rear portion with each other such that the spiral spring is maintained in the state of being unwound by the length equal to or greater than the first length.

In one implementation, the third frame may be maintained in a state of being maximally moved in the reverse direction of the first direction with respect to the third rear portion in a first state, wherein the spring member may connect the third frame and the third rear portion with each other in the state where the spiral spring is unwound by the length equal to or greater than the first length in the first state.

In one implementation, when the spiral spring provides the constant attractive force in a state of being unwound by a length equal to or less than a second length, the spring member may connect the third frame and the third rear portion with each other such that the spiral spring is maintained in the state of being unwound by the length equal to or less than the second length.

In one implementation, the third frame may be maintained in a state of being maximally moved in the first direction with respect to the third rear portion in a second state, wherein the spring member may connect the third frame and the third rear portion with each other in the state where the spiral spring is unwound by the length equal to or less than the second length in the second state.

The fixed shaft is a shaft of the first roller.

The spring member includes a wire for connecting an end of the spiral spring and the third frame with each other, and a shaft fixed to the third rear portion and surrounded by the wire such that both ends of the wire are directed in the first direction.

In one implementation, the shaft may include a bearing rotating in response to a movement of the wire.

In one implementation, the first roller may include a first region rotating in contact with a rear face of the flexible display panel, and a second region wound by the spiral spring.

In one implementation, in the first roller, a diameter of the second region may be equal to or smaller than a diameter of the first region in a state where the spiral spring is maximally wound.

In one implementation, the first roller may not rotate in the second region.

According to the above object, the mobile terminal according to an embodiment may prevent a user from recognizing a luminance deviation in dividing a large screen through two drivers and outputting an image.

In addition, the mobile terminal according to an embodiment may prevent the user from recognizing a time difference of the image output in dividing the large screen through the two drivers and outputting the image.

Description will now be given in detail according to exemplary embodiments disclosed herein, with reference to the accompanying drawings. For the sake of brief description with reference to the drawings, the same or equivalent components may be provided with the same reference numbers, and description thereof will not be repeated. In general, a suffix such as "module" and "unit" may be used to refer to elements or components. Use of such a suffix herein is merely intended to facilitate description of the specification, and the suffix itself is not intended to give any special meaning or function. In the present disclosure, that which is well-known to one of ordinary skill in the relevant art has generally been omitted for the sake of brevity. 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. As such, 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.

It will be understood that when an element is referred to as being "connected with" another element, the element can be connected with the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly connected with" another element, there are no intervening elements present.

The mobile terminal <NUM> is shown having components such as a wireless communication unit <NUM>, an input unit <NUM>, a sensing unit <NUM>, an output unit <NUM>, an interface unit <NUM>, a memory <NUM>, a controller <NUM>, and a power supply unit <NUM>. It is understood that implementing all of the illustrated components is not a requirement, and that greater or fewer components may alternatively be implemented. Referring now to <FIG>, the mobile terminal <NUM> is shown having wireless communication unit <NUM> configured with several commonly implemented components. It is understood that implementing all of the illustrated components is not a requirement, and that greater or fewer components may alternatively be implemented.

The mobile communication module <NUM> can transmit and/or receive wireless signals to and from one or more network entities. Typical examples of a network entity include a base station, an external mobile terminal, a server, and the like. Such network entities form part of a mobile communication network, which is constructed according to technical standards or communication methods for mobile communications (for example, Global System for Mobile Communication (GSM), Code Division Multi Access (CDMA), CDMA2000(Code Division Multi Access <NUM>), EV-DO(Enhanced Voice-Data Optimized or Enhanced Voice-Data Only), Wideband CDMA (WCDMA), High Speed Downlink Packet access (HSDPA), HSUPA(High Speed Uplink Packet Access), Long Term Evolution (LTE) , LTE-A(Long Term Evolution-Advanced), and the like).

One example of the wireless area networks is a wireless personal area network.

Such cameras <NUM> may process image frames of still pictures or video obtained by image sensors in a video or image capture mode. The processed image frames can be displayed on the display unit <NUM> or stored in memory <NUM>. In some cases, the cameras <NUM> may be arranged in a matrix configuration to permit a plurality of images having various angles or focal points to be input to the mobile terminal <NUM>. As another example, the cameras <NUM> may be located in a stereoscopic arrangement to acquire left and right images for implementing a stereoscopic image.

The sensing unit <NUM> is typically implemented using one or more sensors configured to sense internal information of the mobile terminal, the surrounding environment of the mobile terminal, user information, and the like. If desired, the sensing unit <NUM> may alternatively or additionally include other types of sensors or devices, such as a touch sensor, an acceleration sensor, a magnetic sensor, a G-sensor, a gyroscope sensor, a motion sensor, an RGB sensor, an infrared (IR) sensor, a finger scan sensor, a ultrasonic sensor, an optical sensor (for example, camera <NUM>), a microphone <NUM>, a battery gauge, an environment sensor (for example, a barometer, a hygrometer, a thermometer, a radiation detection sensor, a thermal sensor, and a gas sensor, among others), and a chemical sensor (for example, an electronic nose, a health care sensor, a biometric sensor, and the like), to name a few. The mobile terminal <NUM> may be configured to utilize information obtained from sensing unit <NUM>, and in particular, information obtained from one or more sensors of the sensing unit <NUM>, and combinations thereof.

The controller <NUM> typically functions to control overall operation of the mobile terminal <NUM>, in addition to the operations associated with the application programs
The controller <NUM> may provide or process information or functions appropriate for a user by processing signals, data, information and the like, which are input or output by the various components depicted in <FIG>, or activating application programs stored in the memory <NUM>.

<FIG> is an exploded perspective view of a mobile terminal according to one embodiment. Further, <FIG> shows perspective views respectively illustrating a first state and a second state viewed from one side of a mobile terminal according to one embodiment. Further, <FIG> shows rear face views respectively illustrating a first state and a second state of a mobile terminal according to one embodiment. Further, <FIG> shows cross-sectional views respectively taken along a line A-A and a line B-B of <FIG>. In these drawings, <FIG>, <FIG>, and <FIG> show a first state of the mobile terminal, and <FIG>, <FIG>, and <FIG> show a second state of the mobile terminal.

As shown, a mobile terminal <NUM> in a first state is contracted, and has a smaller size than the mobile terminal <NUM> in a second state. In addition, a size of a display unit <NUM> located disposed on a front face of the mobile terminal <NUM> also becomes smaller than that of the display unit <NUM> in the second state. The mobile terminal <NUM> of the first state is expanded in a first direction D1 to be in the second state. In the second state, a size of the mobile terminal <NUM> and a size of the front face of the display unit <NUM> become larger than that in the first state as shown in <FIG>, and a size of the rear face of the display unit <NUM> is reduced as shown in <FIG>. That is, the display unit <NUM> positioned on the rear face of the mobile terminal <NUM> in the first state moves to the front face of the mobile terminal <NUM> in the second state.

In a following description, a direction in which the mobile terminal <NUM> and the display <NUM> thereof are extended or enlarged is referred to as a first direction D1, a direction in which the mobile terminal <NUM> and the display <NUM> thereof are contracted or retracted, or reduce to be converted into the first state from the second state is referred to as a second direction D2, and a direction perpendicular to the first and second directions D1 and D2 is referred to as a third direction.

As such, the display unit may use a flexible display unit <NUM> that may be bent such that the position of the display unit may be varied. The flexible display is a lightweight, unbreakable, and durable display that is built on a thin and flexible substrate that may be bent, crooked, folded, twisted, or rolled while retaining properties of a conventional flat panel display.

In addition, an electronic paper is a display technology to which properties of general ink are applied. The electronic paper may be different from the conventional flat panel display in using reflected light. The electronic paper may change information using a twisted ball or electrophoresis using a capsule.

In a state in which the flexible display unit <NUM> is not deformed (e.g., a state of having an infinite curvature radius, hereinafter referred to as a basic state), a display region of the flexible display unit <NUM> becomes flat. In a state in which the flexible display unit <NUM> is deformed by an external force from the basic state (e.g., a state of having a finite radius of curvature, hereinafter referred to as a deformed state), the display region may become a curved face. As shown, information displayed in the deformation state may be visual information output on the curved face. Such visual information is implemented by independently controlling light emission of sub-pixels arranged in a matrix. The sub-pixel refers to a minimum unit for implementing one color.

The flexible display unit <NUM> may be in a curved state (e.g., a vertically or horizontally curved state) rather than a flat state in the basic state. In this case, when the external force is applied to the flexible display unit <NUM>, the flexible display unit <NUM> may be deformed into the flat state (or a less curved state) or more curved state.

The flexible display unit <NUM> may be combined with a touch sensor to implement a flexible touch screen. When a touch is made on the flexible touch screen, the controller <NUM> (see <FIG>) may perform control corresponding to such touch input. The flexible touch screen may be configured to detect the touch input in the deformed state as well as in the basic state.

The touch sensor detects the touch (or touch input) applied on the touch screen using at least one of various touch schemes such as a resistive film scheme, a capacitance scheme, an infrared scheme, an ultrasonic wave scheme, a magnetic field scheme, and the like.

As an example, the touch sensor may be configured to convert a change in pressure applied on a specific portion of the touch screen, capacitance generated at the specific portion, or the like into an electrical input signal. The touch sensor may be configured such that a touch object applying a touch on the touch screen may detect touched position and area on the touch sensor, a pressure during the touch, a capacitance during the touch, and the like.

Further, the mobile terminal <NUM> may have a deformation detection means for detecting the deformation of the flexible display unit <NUM>. Such deformation detection means may be included in the sensing unit <NUM> (see <FIG>).

The deformation detection means may be disposed in the flexible display unit <NUM> or a case (first to second frames <NUM> to <NUM> to be described later) to detect information related to the deformation of the flexible display unit <NUM>. In this connection, the information related to the deformation may include a direction in which the flexible display unit <NUM> is deformed, a degree of the deformation, a deformed position, a deformed time, an acceleration at which the deformed flexible display unit <NUM> is restored, and the like. In addition, the information related to the deformation may be various information that may be detected due to the bending of the flexible display unit <NUM>.

In addition, the controller <NUM> may change information displayed on the flexible display unit <NUM> or generate a control signal for controlling a function of the mobile terminal <NUM> based on the information related to the deformation of the flexible display unit <NUM> detected by the deformation detection means.

The state conversion (first or second state) of the flexible display unit <NUM>, i.e., the size change at the front and rear faces of the mobile terminal <NUM> of the display unit <NUM> based on the size change of the mobile terminal <NUM> may be performed manually by a force applied by the user, but may be not limited to such manual scheme. For example, when the mobile terminal <NUM> or the flexible display unit <NUM> is in the first state, the mobile terminal <NUM> or the flexible display unit <NUM> may be converted into the second state by the user or an application command without the external force applied by the user. As such, in order for the flexible display unit <NUM> to be automatically deformed without the external force, the mobile terminal <NUM> may include a driving unit <NUM> to be described later.

The flexible display unit <NUM> of the present disclosure is bent <NUM> degrees while being rolled on a side of the mobile terminal <NUM> in the first direction. Thus, a portion of the display unit <NUM> is disposed on the front face of the mobile terminal <NUM> based on such side, and the other portion thereof is disposed on the rear face of the mobile terminal <NUM>. A portion of the display unit <NUM> located on the front face of the mobile terminal <NUM> may be fixed to the front face so as not to move. Further, the other portion thereof located on the rear face of the mobile terminal <NUM> may be movable to the rear face.

In addition, the display unit <NUM> may be rolled on or released from the side. Accordingly, the portion disposed on the rear face of the mobile terminal <NUM> moves, so that the size of the portion disposed on the front face of the mobile terminal <NUM> may be adjusted. Since the area of the flexible display unit <NUM> is determined and the flexible display unit <NUM> is formed of one continuous body, an area of the portion on the rear face decreases as an area of the portion on the front face increases. Such a display unit <NUM> may be rolled in a second frame <NUM>, which is movable relative to a first frame <NUM> to be described later, more correctly, on one of sides of the second frame <NUM>. The display unit <NUM> may be withdrawn or pulled out from or inserted or pushed into the second frame <NUM> while being rolled in the second frame <NUM> along a moving direction of the second frame <NUM> to adjust the area of the display unit <NUM> on the front face of the mobile terminal <NUM>. Such operation will be described in more detail below along with other relevant components of the mobile terminal <NUM>.

Typically, an antenna is disposed in the case or the housing of the mobile terminal <NUM>, but a portion where the antenna is installed in the case or the housing may be limited because of the flexible display unit <NUM> that covers not only the front face of the mobile terminal <NUM> but also the rear face thereof. For this reason, the antenna may be implemented on the flexible display unit <NUM>. An antenna on display (AOD) is an antenna in which a transparent film is formed by stacking an electrode layer and a dielectric layer that have patterns engraved thereon, respectively. The antenna on display may be implemented thinner than an antenna implemented using a laser direct structuring (LDS) technology using a conventional copper nickel plating scheme, so that the antenna on display may not be exposed to the outside without affecting a thickness. In addition, the antenna on display may transmit and receive a signal directly to or from the display unit <NUM>. Accordingly, the antenna on display may be used in the mobile terminal <NUM> in which the display unit <NUM> is located on the both faces of the mobile terminal <NUM> as in the present disclosure.

Referring to <FIG>, a detailed configuration of the mobile terminal <NUM> according to the present disclosure will be described in detail below. In a following description, <FIG> illustrating an overall configuration is basically referred to, and <FIG> are referred to describe detailed features of corresponding components in the first and second states of the mobile terminal <NUM>.

The mobile terminal <NUM> of the present disclosure includes frames <NUM> and <NUM> in which components are mounted, and the frames <NUM> and <NUM> of the present disclosure may vary in size in the first direction as shown in <FIG>. One or more frames <NUM> and <NUM> move relative to each other, and sizes thereof may vary in the first direction. Electronic components are mounted in the frames <NUM> and <NUM>, and the flexible display unit <NUM> is located out of the frames <NUM> and <NUM>.

Since the mobile terminal <NUM> of the present disclosure includes the flexible display unit <NUM>, the flexible display unit <NUM> may be combined in a form surrounding front faces and rear faces of the frames <NUM> and <NUM>. The frame may include the first frame <NUM> and the second frame <NUM> moving in the first direction with respect to the first frame <NUM>. The first frame <NUM> and the second frame <NUM> include front portions, rear portions, and side portions, respectively, and are coupled to each other. Thus, the mobile terminal <NUM> may have a hexahedral outer shape by such coupled first and second frames <NUM> and <NUM>.

First, the first frame <NUM> corresponds to a main body of the mobile terminal <NUM>, and may have a space therein for accommodating various components. In addition, the first frame <NUM> may accommodate the second frame <NUM> movably coupled to the first frame <NUM> in such a space. More specifically, as shown in <FIG> and <FIG>, the first frame <NUM> may include a first front portion <NUM> disposed at a front portion of the mobile terminal <NUM> and supporting the front face of the display unit <NUM> and a first rear portion <NUM> disposed at a rear portion of the mobile terminal and on which various components are mounted.

The first front portion <NUM> and the first rear portion <NUM> may be spaced apart from each other at a predetermined spacing to define a predetermined space therebetween, and may be connected to each other by a side portion <NUM>. The side portion <NUM> may be integrally formed with the first rear portion <NUM> or the first front portion <NUM>. The camera <NUM>, the audio output module <NUM>, and the input/output terminal <NUM>, the controller <NUM>, and the power supply unit <NUM> may be accommodated as components of the mobile terminal <NUM> in the space in the first frame <NUM>. For example, the controller <NUM> may be a circuit board <NUM> including a processor and an electronic circuit for controlling the operation of the mobile terminal, and the power supply unit <NUM> may be a battery <NUM> and related components. In addition, the driving unit <NUM> that controls the slide movement of the second frame <NUM>, which will be described later, may also be accommodated in the first frame <NUM>.

As described above, the display unit <NUM> has the continuous body, and thus, may be disposed on both the front face and the rear face of the mobile terminal <NUM> while being rolled in the mobile terminal <NUM>. The display unit <NUM> may include the front face positioned at the front face of the mobile terminal <NUM>, the rear face positioned at the rear face of the mobile terminal <NUM>, and the side face positioned between the front face and the rear face thereof and surrounding the side face of the mobile terminal. The front face and the rear face of the display unit <NUM> are flat, and the side face of the display unit <NUM> may form a curved face. When the flexible display unit <NUM> may be damaged when being bent. Thus, the flexible display unit <NUM> may be formed to be bent with a predetermined curvature.

The display unit <NUM> may be divided into a fixed portion and a variable portion. The fixed portion means a portion fixed to the frame. Because of being fixed to the frame, the fixed portion maintains a constant shape without changing a bending degree. On the other hand, the variable portion means a portion in which a bending angle or a position of the bent portion changes. The variable portion in which the position or bending angle of the bent portion changes requires a structure for supporting a rear face of the variable portion in response to the change.

A first region <NUM> of the display unit <NUM> may be coupled to the first front portion <NUM> corresponding to the front face of the mobile terminal <NUM>.

In one example, as illustrated well in <FIG>, the various physical input units <NUM> and the sensing unit <NUM> for manipulation of the mobile terminal <NUM> may be located on the first rear portion <NUM>, and the display unit <NUM> may be disposed only on a second rear portion <NUM>. The first rear portion <NUM> is not overlapped with the flexible display unit <NUM> regardless of the state of the mobile terminal, and is always exposed to the outside. Thus, the input unit <NUM> such as various buttons, a switch, the camera <NUM>, and a flash, and the sensing unit <NUM> such as a proximity sensor <NUM> may be disposed on the first rear portion <NUM>. In a usual bar-type terminal, a display unit is provided only on a front face of a terminal. Therefore, in order for a user to photograph an object on the other side while viewing the display unit, a main camera is disposed on a rear face of the terminal. In one example, in order for the user to photograph while viewing himself through the display unit, an auxiliary camera is additionally required on the front face of the terminal.

However, in the mobile terminal <NUM> according to the present disclosure, the display unit <NUM> is located on both the front face and the rear face of the terminal. Therefore, when the user photographs himself, a display unit on the same face as the camera <NUM>, that is, a portion of the display unit <NUM> on the rear face of the mobile terminal <NUM> in the drawing may be used. When the user photographs the object on the other side of the user, a display unit on an opposite side to the camera <NUM>, that is, a portion of the display unit <NUM> on the front face of the mobile terminal <NUM> in the drawing may be used. For this reason, the mobile terminal <NUM> may use one camera <NUM> to photograph the object located on the opposite side of the user or to photograph the user. The camera may include a plurality of cameras having different angles of view, such as a wide angle, a super wide angle, a telephoto, and the like. In addition to the camera, the proximity sensor, a sound output unit, and the like may be located on the first rear portion <NUM>, and an antenna <NUM> may be installed on the first rear portion <NUM>.

The side portion <NUM> may extend along edges of the first front portion <NUM> and the first rear portion <NUM>/the second rear portion <NUM> so as to surround a perimeter of the first frame <NUM>, and may form an outer shape of the mobile terminal <NUM>. However, as mentioned above, the second frame <NUM> is accommodated in the first frame <NUM> and is also movably coupled to the first frame <NUM>. Thus, in order to allow a relative movement of the second frame <NUM> for the first frame <NUM>, a portion of the first frame <NUM> needs to be opened. As well illustrated in <FIG>, as an example, the second frame <NUM> is movably coupled to one of both side portions of the first frame <NUM>, so that the first frame <NUM> may include a first side portion 101a that is substantially closed and a second side portion 101b that is disposed opposite to the first side portion 101a and opened. Because the side portion <NUM> is exposed to the outside of the mobile terminal <NUM>, the interface unit <NUM> for connecting a power port or an ear jack, the user input unit <NUM> such as a volume button, and the like may be arranged thereon. When the side portion <NUM> contains a metal material, the side portion <NUM> may serve as an antenna.

The second rear portion <NUM> of the first frame <NUM> may be covered by the display unit, but may also be disposed on the front face of the display unit using a transparent material.

The second frame <NUM> may include a second front portion <NUM> disposed at the front portion of the mobile terminal <NUM> and a third rear portion <NUM> disposed at the rear portion of the mobile terminal <NUM>. Like the first front portion <NUM> and the first rear portion <NUM> of the first frame <NUM>, the second front portion <NUM> and the third rear portion <NUM> may be made of a substantially flat plate-shaped member. In addition, the second frame <NUM> accommodates various components therein, and should not interfere with components accommodated in the first frame <NUM> during a movement. Therefore, the second front portion <NUM> and the third rear portion <NUM> may be coupled to each other in a state of being spaced apart from each other to define a predetermined space therebetween, and may have a shape that does not interfere with the components in the first frame <NUM>.

In addition, the display unit <NUM> may be bent <NUM> degrees while being wound inside the second frame <NUM> so as to be disposed on both the front face and the rear face of the mobile terminal <NUM>. For such an arrangement of the display unit <NUM>, the second frame <NUM> may include a roller <NUM> rotatably disposed therein. The roller <NUM> may be disposed at any position inside the second frame <NUM>. However, the display unit <NUM> must be spread flat on the front face and rear face of the mobile terminal <NUM> in order to provide a good quality screen to the user. For such spread, an adequate tension must be provided to the display unit <NUM>. In order to provide the adequate tension, the roller <NUM> may be disposed at a first directional end of the second frame <NUM>. Such roller <NUM> may be extended in the second direction, and may be rotatably coupled to the second frame <NUM>.

The display unit <NUM> may be wound on the roller <NUM> while gently bending with a predetermined curvature. The flexible display unit <NUM> may include a first face on which an image is output and is exposed to the outside, and an inner face facing the frame on the opposite side. The roller <NUM> may be installed to freely rotate in the second frame <NUM> while being in contact with the inner face of the display unit <NUM>. Therefore, the roller <NUM> may actually move the display unit <NUM> in a lateral direction, that is a direction perpendicular to a longitudinal direction of the mobile terminal <NUM>. As will be described below, when the second frame <NUM> slides, the display unit <NUM> may move to the front face or the rear face of the mobile terminal <NUM> relative to the second frame <NUM> in different directions (i.e., the first direction D1 or the second direction D2) by the tension applied by the second frame <NUM>. The roller <NUM> may guide such movement while rotating.

In addition, the roller <NUM> is disposed on a first side portion 102a of the second frame <NUM>, and the first side portion 102a actually corresponds to an outermost side portion of the mobile terminal <NUM>. When the first side portion 102a of the second frame <NUM> is exposed, the display unit <NUM> wound on the roller <NUM> may be damaged. Accordingly, the second frame <NUM> may include a side frame <NUM> disposed on the first side portion 102a.

The side frame <NUM> may extend in a longitudinal direction of the second frame <NUM> to cover the first side portion 102a, thereby protecting the roller <NUM> and the display unit <NUM> wound on the roller <NUM>. That is, the side frame <NUM> covers the side face of the display unit <NUM>, and the side face is located in a third region. The first region <NUM> to the third region are respectively located at specified positions and do not change in size or position, but sizes of the front face and rear face and a position of the side face of the display unit <NUM> are determined based on a state of a main frame.

The first region <NUM> and the second region <NUM> correspond to the aforementioned fixed portion, and the third region <NUM> corresponds to the aforementioned variable portion.

The position of the third region <NUM> may vary based on the state of the mobile terminal. Because the side face is wound by the roller, the side face may be bent with a predetermined curvature, and an inner face of the side frame may have a curved face corresponding to the curvature of the side face.

The second frame <NUM> may have the substantially closed first side portion 102a by such side frame <NUM>, and the side frame <NUM> may substantially form the outer shape of the mobile terminal <NUM> together with the side portion <NUM> of the first frame <NUM>. In addition, in order to minimize interference with the components in the first frame <NUM> during the movement, the second frame <NUM> may include a second side portion 102b disposed opposite to the first side portion 102a and opened.

Such second frame <NUM> may be movably coupled to the first frame <NUM>, and accordingly, may slide in the predetermined first or second direction D1 or D2 with respect to the first frame <NUM>. More specifically, as described above, the second frame <NUM> may be movably coupled to the first frame <NUM> through the side portion of the first frame <NUM>, precisely through the open second side portion 101b. More specifically, the second side portion 102b of the second frame may be disposed relatively adjacent to the first side portion 101a of the first frame <NUM> to be closed. Accordingly, the first side portion 102a of the second frame may be disposed opposite to the first side portion 101a. Accordingly, the second side portion 102b may be inserted into the first frame <NUM> through the side portion of the first frame, that is, the second side portion 101b thereof. The first side portion 102a may not be inserted into the first frame <NUM> and may always be located outside the first frame <NUM>. Accordingly, as described above, the first side portion 102a may form the outer shape of the mobile terminal <NUM>. However, if necessary, such first side portion 102a of the second frame <NUM> may also be inserted into the first frame <NUM>.

Because of such positional relationship, the second frame <NUM> may be expanded from or contracted into the first frame <NUM> in a direction perpendicular to the longitudinal direction of the mobile terminal <NUM> or the first frame <NUM>. That is, the first and second directions D1 and D2 may be basically directions perpendicular to the longitudinal direction of the mobile terminal <NUM> or the first frame <NUM>. In one example, the first and second directions D1 and D2 may also be described as a lateral direction or a horizontal direction of the mobile terminal <NUM> or the first frame <NUM>. In addition, in the movement in the first direction D1, the second frame <NUM> is extended from the first frame <NUM>. Accordingly, the first direction D1 may be a direction in which the second frame <NUM> moves away from the first frame <NUM>, that is, outwardly of the mobile terminal <NUM> or the first frame <NUM>. On the other hand, in the movement in the second direction D2, the second frame <NUM> is contracted into the first frame <NUM>. Therefore, the second direction D2 may be a direction opposite to the first direction D1. In addition, the second direction D2 may be a direction in which the second frame <NUM> moves to be closer to the first frame <NUM>, that is, inwardly of the mobile terminal <NUM> or the first frame <NUM>. When moved in the first direction D1, such second frame <NUM> may be expanded, may apply a force to the portion of the display unit <NUM> that was disposed on the rear face of the mobile terminal <NUM> to additionally dispose the portion of the display unit <NUM> on the front face of the mobile terminal <NUM>, and may define a region for such additional disposition. Accordingly, the second frame <NUM> may switch the state of the mobile terminal <NUM> to the second state having a relatively expanded front face display unit <NUM> by the movement in the first direction D1. On the other hand, when moved in the second direction D2, the second frame <NUM> may be contracted to an original state, and may apply a force to the portion of the display unit <NUM> that was disposed on the front face of the mobile terminal <NUM> to return the portion of the display unit <NUM> to the rear face of the mobile terminal <NUM> again. Accordingly, the second frame <NUM> may switch the state of the mobile terminal <NUM> to the first state having a relatively reduced front face display unit <NUM> by the movement in the second direction D2. Therefore, the second frame <NUM> may selectively expose the display unit <NUM> on the front face of the mobile terminal <NUM> based on to the movement direction (i.e., the first or the second direction D1 or D2), and accordingly, switch the state of the mobile terminal <NUM> to the first or the second state defined above.

During such expansion and contraction in the first and the second directions D1 and D2, the second frame <NUM> may overlap with the first frame <NUM>, precisely, the first front portion <NUM> and the first rear portion <NUM> thereof so as not to interfere with the first frame <NUM>. More specifically, the display unit <NUM> may be coupled to and supported by the first front portion <NUM> of the first frame <NUM>, as described above. Accordingly, the display unit <NUM> does not need to be additionally supported by the second front portion <NUM> of the second frame <NUM>. When the second front portion <NUM> is interposed between the first front portion <NUM> and the display unit <NUM>, the display unit <NUM> may rather be deformed or damaged due to friction between the second front portion <NUM> that moves repeatedly. Accordingly, the second front portion <NUM> may be disposed below the first front portion <NUM> as illustrated well in <FIG>. That is, a front face of the second front portion <NUM> may face a rear face of the first front portion <NUM>. In addition, the rear face of the first front portion <NUM> may be in contact with the front face of the second front portion <NUM> to stably support the movement of the second frame <NUM>.

The third rear portion <NUM> of the second frame <NUM> may be disposed below the second rear portion <NUM> of the first frame <NUM>. That is, a front face of the third rear portion <NUM> may face a rear face of the second rear portion <NUM>. In addition, the rear face of the second rear portion <NUM> may be in contact with the front face of the third rear portion <NUM> to stably support the movement of the second frame <NUM>. By such arrangement, the third rear portion <NUM> may be exposed to the outside of the first frame, precisely, of the second rear portion <NUM>, and may be coupled to the display unit <NUM>.

Alternatively, when the second rear portion <NUM> is made of a transparent material, the second rear portion <NUM> may form an outer shape of the rear face of the mobile terminal. The second rear portion <NUM> may be located rearward of the third rear portion <NUM> of the second frame, and the flexible display unit may be located between the second rear portion <NUM> and the third rear portion <NUM> in the first state.

When the second rear portion <NUM> forms the outer shape of the rear face of the mobile terminal using a material such as transparent glass, the first rear portion <NUM> may be implemented using the same member as the second rear portion <NUM>. That is, a plate-shaped member made of the transparent glass may be partially coated such that the internal components are not visible and the coating may be omitted only for a necessary portion to arrange the camera <NUM>, the flash, the sensing unit <NUM>, or the like.

In addition, the second frame <NUM> may expand and contract the mobile terminal <NUM> itself, particularly, the front face of the mobile terminal <NUM> by the expansion and the contraction in the first and the second directions D1 and D2. The display unit <NUM> must move by such the expanded or contracted front face to obtain the intended first and second states. However, when fixed to the second frame <NUM>, the display unit <NUM> may not be moved smoothly based on the front face of the mobile terminal <NUM> that is expanded or reduced. For this reason, the display unit <NUM> may be movably coupled to the second frame <NUM>. More specifically, the display unit <NUM> may include a first side end 151d disposed on the front face of the mobile terminal <NUM> and a second side end 151e opposite to the first side end 151d and disposed on the rear face of the mobile terminal <NUM>. The first side end 151d may be disposed on the front face of the first frame <NUM>, that is, a front face of the first front portion <NUM>, and may be disposed adjacent to the side portion of the mobile terminal <NUM>, that is, the first side portion 101a of the first frame. On the other hand, because the second end 151e is adjacent to the rear face of the mobile terminal <NUM>, that is, the third rear portion <NUM> of the second frame <NUM>, the second end 151e may be coupled to the third rear portion <NUM> of the second frame <NUM> in a manner of being movable in the first and second directions D1 and D2. In addition, the display unit <NUM> is not structurally strong, so that a third frame <NUM> may be coupled to such second end 151e. The third frame <NUM> may be formed of a plate-shaped member extending in the longitudinal direction of the mobile terminal <NUM>. Accordingly, the third frame <NUM> may be coupled to the second frame, that is, the third rear portion <NUM> of the second frame in a manner of being movable in the first and second directions D1 and D2, in place of the second end 151e. In addition, the second frame <NUM> may include a slot <NUM> extending in the lateral direction of the mobile terminal <NUM> or the second frame, that is, a direction perpendicular to the longitudinal direction of the mobile terminal <NUM> or the second frame. The third frame <NUM> may be stably moved while being guided by the slot <NUM>. The third frame <NUM> may include, for example, a protrusion inserted into the slot <NUM> for the movement along the slot <NUM>.

Referring to <FIG>, in connection with the configuration of the first to third frames <NUM>, <NUM>, and <NUM>, the display unit <NUM> may include the first region <NUM> extending from one side of the display <NUM>, that is, the first side end 151d to the second side end 151e opposite to the first side end 151d with a predetermined length, and the second region <NUM> disposed opposite to the first region <NUM> and extending from the second side end 151e to the first side end 151d with a predetermined length. In addition, the display unit <NUM> may include the third region <NUM> disposed between the first and the second regions <NUM> and <NUM>. Such first to third regions <NUM>,<NUM>, and1513 may be connected to each other, and may form the continuous body of the display unit <NUM>. In addition, as described above, for the movement of the third region <NUM> to the front face or rear face of the mobile terminal <NUM> based on the movement direction of the second frame <NUM>, the first region <NUM> may be fixed so as not to move on the front face of the mobile terminal <NUM>, and the second region <NUM> may be provided movably on the rear face of the mobile terminal. Such configuration of the display unit <NUM> will be described in more detail below.

The first region <NUM> may be disposed on the front face of the mobile terminal <NUM>, and more specifically, on the front face of the first frame <NUM>, that is, the first front portion <NUM>. The first region <NUM> is fixed to the first frame <NUM>, that is, the front face of the first front portion <NUM> so as not to move even when the second frame <NUM> moves. Accordingly, the first region <NUM> may always be exposed on the front face of the mobile terminal <NUM>. The third region <NUM> may be adjacent to the first region <NUM>, and may extend into the second frame <NUM> to be wound on the roller <NUM>. The third region <NUM> may continuously extend out of the second frame <NUM> again and partially cover the second frame <NUM>, that is, the rear face of the third rear portion <NUM>. In one example, the second frame <NUM>, that is, the third rear portion <NUM> is adjacent to the first frame <NUM>, that is, the second rear portion <NUM> and forms a rear casing of the mobile terminal <NUM> together with the first frame <NUM>, that is, the second rear portion <NUM>. Therefore, it may be described that the third region <NUM> is also disposed on the rear face of the first frame <NUM>.

The second region <NUM> may be adjacent to the third region <NUM>, and may be disposed on the rear face of the mobile terminal <NUM>, and more specifically, on the second frame, that is, the rear face of the third rear portion <NUM> of the second frame. The second region <NUM> may be coupled to the third frame <NUM> rather than directly coupled to the second frame <NUM>. As shown in (b) in <FIG>, the slot <NUM> extending in the lateral direction (i.e., the direction perpendicular to the longitudinal direction of the mobile terminal <NUM>) may be defined in the second frame <NUM>, that is, the third rear portion <NUM>, and the third frame <NUM> may move along the slot <NUM>. In (b) in <FIG>, the slot <NUM> is illustrated as being defined in the rear face of the second frame <NUM>, but may be defined in a side face of the second frame <NUM>. The second region <NUM> may move in the first or second direction D1 or D2 with respect to the second frame <NUM> together with the third frame <NUM>, but a range of the movement of the second region <NUM> may be limited to the rear face of the mobile terminal <NUM> by the slot <NUM>. That is, the second region <NUM> may not move out of the second frame <NUM> even when the second frame <NUM> expands or contracts, and may move along the slot <NUM> within the second frame <NUM> by an extended or contracted length of the second frame <NUM>. Thus, the second region <NUM> may always be exposed on the rear face of the mobile terminal <NUM>.

As a result, the first region <NUM> may be disposed on the front face of the mobile terminal <NUM> and may always be exposed to the front face regardless of the movement of the second frame <NUM>. The second region <NUM> may be disposed on the rear face of the mobile terminal <NUM> and may always be exposed to the rear face regardless of the movement of the second frame <NUM>. In addition, the third region <NUM> may be disposed between the first and second regions <NUM> and <NUM>, and may be selectively disposed on the front or rear face of the mobile terminal <NUM> based on the movement directions D1 and D2 of the second frame <NUM>.

Because of such selective disposition of the third region <NUM>, as shown in FIG. (b) in <FIG>, the second rear portion <NUM> of the first frame <NUM> may be covered by the second and third regions <NUM> and <NUM> of the display unit <NUM> and the third rear portion <NUM> in the first state, but may be exposed to the outside of the mobile terminal <NUM> in the second state because the third region <NUM> moves to the front face of the mobile terminal <NUM> and the third rear portion <NUM> also moves in the first direction D1. In addition, the second front portion <NUM> of the second frame <NUM> may be disposed below the first front portion <NUM> of the first frame <NUM> in the first state, but the second front portion <NUM> may be moved out of the first frame <NUM> in the second state to support the third region <NUM> of the display unit <NUM> disposed on the front face of the mobile terminal <NUM>.

The first and second regions <NUM> and <NUM> are always respectively arranged on the front face and the rear face of the mobile terminal <NUM>, so that curvatures of the first region <NUM> and the second region <NUM> may not be changed and maintained in a flat basic state. However, the third region <NUM> may be wound on the roller <NUM> and bent within the second frame <NUM>. When switching from the first state to the second state, the third region <NUM> may be extended from the second frame <NUM> to the front face of the mobile terminal <NUM> while being wound in one direction on the roller <NUM>. On the other hand, when switching from the second state to the first state, the third region <NUM> may contract to the second frame <NUM> from the front face of the mobile terminal <NUM> while being wound on the roller <NUM> in the opposite direction. At the same time, the third region <NUM> may return to the rear face of the mobile terminal <NUM> from the second frame <NUM>. Only a specific position of a foldable mobile terminal in a form of being unfolded like a book is repeatedly folded, so that the specific position thereof is likely to be damaged. On the other hand, a deformed portion of the flexible display unit <NUM>, that is, a portion wound on the roller <NUM> may be changed based on the first and second states of the mobile terminal <NUM>, that is, the movement of the second frame <NUM>. Therefore, the mobile terminal <NUM> according to the present disclosure may significantly reduce deformation and fatigue repeatedly applied to a specific portion of the display unit <NUM>, thereby preventing damage to the display unit <NUM>.

Based on the above-described configuration, an overall operation of the mobile terminal <NUM> will be described as follows. As an example, the switching of the state may be manually performed by the user, and an operation of the mobile terminal <NUM> during such manual state switching will be described. However, operations of the first to third frames <NUM> to <NUM> and the display unit <NUM> to be described below may be performed in the same manner when a power source other than the force of the user is used, for example, when the driving unit <NUM> to be described below is applied.

As shown in (a) in <FIG>, <FIG> in <FIG>, and <FIG> in <FIG>, the second frame <NUM> is completely contracted into the first frame <NUM> in the first state. Therefore, only the first region <NUM> of the display unit <NUM> fixed to the front face of the first frame <NUM> may be exposed to the front face of the mobile terminal <NUM>. Such first region <NUM> may be fixed to and supported by the first frame <NUM>, that is, the first front portion <NUM> of the first frame <NUM>. In addition, a great portion of the third region <NUM> is disposed on the rear face of the mobile terminal <NUM> together with the second region <NUM>, and may be disposed in the second frame <NUM> in a state of being partially wound on the roller <NUM>. The third region <NUM> on the rear face of the mobile terminal <NUM> may be supported by the second frame, that is, the third rear portion <NUM> of the second frame. The second region <NUM> may be fixed by the third frame <NUM> disposed on the second frame (i.e., the third rear portion <NUM>), and may be movably coupled to the second frame <NUM>.

In such first state, when the second frame <NUM> moves in the first direction D1, the mobile terminal <NUM> may be switched to the second state. As shown in (b) in <FIG>, <FIG> in <FIG>, and <FIG> in <FIG>, the second frame <NUM> may be extended from the first frame <NUM> by the movement in the first direction D1, and may increase an overall size of the mobile terminal <NUM>, in particular, a size of the front face of the mobile terminal <NUM>. During such movement in the first direction D1, the second frame <NUM> may apply the force, that is, the tension, to the display unit <NUM> in the first direction D1. The display unit <NUM> is fixed to the first frame <NUM>, but is movably coupled to the second frame <NUM> using the third frame <NUM>. Thus, the third region <NUM> may be rolled out from the roller <NUM> in the second frame <NUM> to the front face of the mobile terminal <NUM> by the force applied by the second frame <NUM>. That is, the third region <NUM> may be withdrawn or pulled out, extended, or moved out from the second frame <NUM>. At the same time, the third region <NUM>, particularly a portion of the third region <NUM> disposed on the rear face of the mobile terminal <NUM>, may be rolled into the second frame <NUM>, or inserted or pushed in, retracted, or moved into the second frame <NUM>. An entirety of the third region <NUM> may not be withdrawn from the second frame <NUM> to the front face of the mobile terminal <NUM>, and a portion of the third region <NUM> may still be disposed in the second frame <NUM> in a state of being wound on the roller <NUM>. In addition, for the smooth movement of such third region <NUM>, the second region <NUM> may also move in the first direction D1 with respect to the second frame <NUM> along with the third frame <NUM>. In addition, as described above, the second region <NUM> and the third frame <NUM> may be constrained to the second frame <NUM> and move in the first direction D1 with respect to the first frame <NUM> together with the second frame <NUM>. Accordingly, the second region <NUM> and the third frame <NUM> may move relatively in the first direction D1 with respect to the first frame <NUM> as well as to the second frame <NUM>. Accordingly, a moved distance of the second region <NUM> and the third frame <NUM> may be greater than a moved distance of the second frame <NUM>. Therefore, because of the movement of the long distance in the first direction D1 of the second region <NUM>, the third region <NUM> may be smoothly expanded to the front face of the mobile terminal <NUM>. In addition, for the movement of the third region <NUM> proportional to the expansion of the second frame <NUM>, the movement of the second region <NUM> and the third frame <NUM> in the first direction D1 may be simultaneously performed with the movement of the third region <NUM> and the second frame <NUM> so as to be proportional to the movement of the third region <NUM> and the second frame <NUM>.

When the second frame <NUM> is completely expanded in the first direction D1, the first and third regions <NUM> and <NUM> are arranged on the front face of the mobile terminal <NUM>, and only the second region <NUM> may be disposed on the rear face of the mobile terminal <NUM>. Such first and third regions <NUM> and <NUM> may be supported by the first frame (i.e., the first front portion <NUM> thereof) and the second frame (i.e., the second front portion <NUM> thereof). In addition, the second frame <NUM>, that is, the third rear portion <NUM> thereof may expose the second rear portion <NUM> of the first frame while expanding in the first direction D1 and may support the moving third region <NUM>. Therefore, in the second state, the mobile terminal <NUM> may have the expanded front face display unit <NUM>.

On the other hand, when the second frame <NUM> moves in the second direction D2 in the second state, the mobile terminal <NUM> may return to the first state again as illustrated in (a) in <FIG> in <FIG> in <FIG>. The second frame <NUM> may be contracted into the first frame <NUM> by the movement in the second direction D2, and may reduce the overall size of the mobile terminal <NUM>, in particular, the front face of the mobile terminal <NUM>. During such movement of the second frame <NUM>, the movement of the display unit <NUM> may be performed in a reverse order to the movement in the first direction D1 described above. Briefly, the third region <NUM> may be rolled into the second frame <NUM> and wound on the roller <NUM> from the front face of the mobile terminal <NUM> or may be inserted, retracted, or moved into the second frame <NUM>. At the same time, the third region <NUM> may be rolled out, withdrawn or pulled out, or moved out to the rear face of the mobile terminal <NUM> from the roller <NUM> of the second frame <NUM>. Not the entirety of the third region <NUM> is withdrawn from the second frame <NUM> to the rear face of the mobile terminal <NUM>. A portion of the third region <NUM> may still be disposed in the second frame <NUM> in a state of being rolled on the roller <NUM>. In addition, for the smooth movement of such third region <NUM>, the second region <NUM> may also move in the second direction D2 with respect to the second frame <NUM> along with the third frame <NUM>. The second region <NUM> and the third frame <NUM> may be constrained to the second frame <NUM> and move in the second direction D2 with respect to the first frame <NUM> together with the second frame <NUM>. Accordingly, the second region <NUM> and the third frame <NUM> may move relatively in the second direction D2 with respect to the first frame <NUM> as well as the second frame <NUM>. Accordingly, a moved distance of the second region <NUM> and the third frame <NUM> in the second direction D2 may be greater than a moved distance of the second frame <NUM> in the second direction D2. Therefore, because of the movement of the long distance of the second region <NUM>, the third region <NUM> may smoothly return to the rear face of the mobile terminal <NUM>. In addition, for the movement of the third region <NUM> proportional to the contraction of the second frame <NUM>, the movement of the second region <NUM> and the third frame <NUM> in the second direction D2 may be simultaneously performed with the movement of the third region <NUM> and the second frame <NUM> so as to be proportional to the movement of the third region <NUM> and the second frame <NUM>. When the second frame <NUM> is completely contracted in the second direction D2, the mobile terminal <NUM> may be switched to the first state as described above and may have the front face display unit <NUM> that is relatively contracted in the first state compared to the second state.

<FIG> is a rear face view of some components of a mobile terminal according to one embodiment. Specifically, (a) in <FIG> is a view corresponding to the first state of the mobile terminal, and (b) in <FIG> is a view corresponding to the second state of the mobile terminal.

The mobile terminal <NUM> according to an embodiment may further include a spring member <NUM> to prevent the flexible display panel <NUM> from being wrinkled. <FIG> is illustrated by omitting the flexible display panel <NUM> for convenience of description. A configuration of the flexible display panel <NUM> may refer to <FIG> below.

The spring member <NUM> may prevent the flexible display panel <NUM> from being wrinkled while the second frame <NUM> of the mobile terminal <NUM> moves with respect to the first frame <NUM>. Specifically, the spring member <NUM> may provide a constant force to the third frame <NUM> in a second direction B opposite to a first direction A.

<FIG> is an exploded view of some components of the mobile terminal <NUM> according to one embodiment.

The mobile terminal <NUM> according to an embodiment may include the first frame <NUM>, the second frame <NUM>, the third frame <NUM>, the flexible display panel <NUM>, the driving unit <NUM>, and the spring member <NUM>.

The first frame <NUM> may include the first front portion <NUM> constituting a front face of the first frame <NUM>, the second rear portion <NUM> constituting a rear face of the first frame <NUM>, and the third rear portion <NUM> protruding from the second rear portion <NUM> in a rear face direction. The first front portion <NUM> and the second rear portion <NUM> may define a mounting space therebetween.

The second frame <NUM> may include the third rear portion <NUM> disposed on the rear face of the first frame <NUM> and coupled to the rear face of the first frame <NUM> in a manner of being movable in the first direction A, and a first roller <NUM> disposed at an end in the first direction A of the third rear portion <NUM>. Specifically, the third rear portion <NUM> may be disposed such that at least a portion thereof overlaps a rear face of the second rear portion <NUM>.

The third frame <NUM> may be disposed on a rear face of the third rear portion <NUM> and may be coupled to the rear face of the third rear portion <NUM> in a manner of being movable in the first direction A or in the second direction B opposite to the first direction A.

The flexible display panel <NUM> may be disposed to surround the first roller <NUM>, so that one end of the flexible display panel <NUM> may be disposed on the front face of the first frame <NUM> and the other end thereof may be disposed on the third frame <NUM>. Specifically, the flexible display panel <NUM> may be disposed to cover a front face of the first front portion <NUM> and cover the first roller <NUM> to cover a rear face of the third frame <NUM>.

The driving unit <NUM> may drive the second frame <NUM> from the first frame <NUM> in the first direction A or in the second direction B that is opposite to the first direction A. A state in which the second frame <NUM> is maximally moved from the first frame <NUM> in the first direction A may correspond to the first state. A state in which the second frame <NUM> is maximally moved from the first frame <NUM> in the second direction B, which is opposite to the first direction A, may correspond to the second state. Specifically, in the second state, the third rear portion <NUM> may cover an entirety of the rear face of the second rear portion <NUM> and be in contact with the third rear portion <NUM>.

A movement of each component in response to the driving of the driving unit <NUM> is as follows. When the second frame <NUM> moves in the first direction A with respect to the first frame <NUM>, the third frame <NUM> may move in the first direction A with respect to the second frame <NUM>. This is because the flexible display panel <NUM> is not a tensioned. Conversely, when the second frame <NUM> is moved in the second direction B with respect to the first frame <NUM>, the third frame <NUM> may move in the second direction B with respect to the second frame <NUM>.

The spring member <NUM> may provide the constant force to the third frame <NUM> in the second direction B. The force provided by the spring member <NUM> may correspond to a force of pulling the flexible display panel <NUM> from one side. The flexible display panel <NUM> may be prevented from being wrinkled using the force provided by the spring member <NUM>. Specifically, the spring member <NUM> may exert the constant force in the second direction B on the third frame <NUM> even when the mobile terminal <NUM> is in the first state or in the second state. In addition, the spring member <NUM> may exert the constant force in the second direction B even when the third frame <NUM> moves in the first direction A. In addition, the spring member <NUM> may exert the constant force in the second direction B even when the third frame <NUM> moves in the second direction B.

As the spring member <NUM> used in the mobile terminal <NUM> according to an embodiment, a constant force spring may be used. The constant force spring will be described below.

<FIG> and <FIG> are views for describing some components of a mobile terminal according to one embodiment. Specifically, <FIG> and <FIG> are diagrams for describing a configuration and a characteristic of the spring member <NUM>.

The spring member <NUM> may include a fixed shaft <NUM>, and a spiral spring <NUM> disposed to be wound around or unwound from the fixed shaft <NUM> to generate a constant attractive force while being wound around or unwound from the fixed shaft <NUM>. Additionally, the spring member <NUM> may include a housing <NUM> in which the spiral spring <NUM> may be mounted in a wound state.

Specifically, (a) in <FIG> shows a state in which the spiral spring <NUM> of the spring member <NUM> is wound. (b) in <FIG> is a perspective view for illustrating an interior of the housing <NUM> of the spring member <NUM>. (c) in <FIG> shows an unwound state of the spiral spring <NUM> of the spring member <NUM>.

The spiral spring <NUM> may be wound around or unwound from the fixed shaft <NUM> while rotating along the fixed shaft <NUM>. Specifically, the fixed shaft <NUM> may not rotate, and an end of the spiral spring <NUM> may not be fixed to the fixed shaft <NUM> and may rotate along the fixed shaft <NUM>. In some cases, the fixed shaft <NUM> may rotate, and the end of the spiral spring <NUM> may be fixed to the fixed shaft <NUM>. The above structure is for generating a constant force in a winding direction while the spiral spring <NUM> is being unwound or wound or in the unwound or wound state of the spiral spring <NUM>. The spring member <NUM> having such characteristic may be the constant force spring.

Specifically, <FIG> is a view for describing a characteristic of the constant force spring. The constant force spring may be a spring that provides a constant force fc in a winding direction while being unwound or wound in a state of being unwound by a length equal to or greater than a first length L1. The constant force spring may provide the constant force fc in the winding direction until being in a state of being unwound by a second length L2.

<FIG> shows an enlarged view and a cross-sectional view of a portion C in <FIG>. <FIG> shows an enlarged view and a cross-sectional view of a portion D in <FIG>.

In the spring member <NUM>, the fixed shaft <NUM> may be fixed to the third frame <NUM>, and the end of the spiral spring <NUM> may be fixed to the third rear portion <NUM> and wound in the first direction A and unwound in the second direction B. In this connection, the second direction B may be opposite to the first direction A.

Specifically, the end of the spiral spring <NUM> may be fixed to a fastening portion <NUM> disposed on the third rear portion <NUM>.

In this case, the third rear portion <NUM> may include a guide groove 1029a recessed in a front face direction such that the spring member <NUM> may move.

The spring member <NUM> may connect the frame <NUM> and the third rear portion <NUM> with each other such that the spiral spring <NUM> is maintained in the state of being unwound by the length equal to or greater than the first length L1 when the spiral spring <NUM> provides a constant attractive force in the state of being unwound by the length equal to or greater than the first length L1. Specifically, referring to (a) in <FIG>, the third frame <NUM> may be maintained in a state of being maximally moved in the second direction B, which is opposite to the first direction A, with respect to the third rear portion <NUM> in the first state. The spring member <NUM> may connect the third frame <NUM> and the third rear portion <NUM> with each other in the state in which the spiral spring <NUM> is unwound by the length equal to or greater than the first length L1 in the first state.

The spring member <NUM> may connect the frame <NUM> and the third rear portion <NUM> with each other such that the spiral spring <NUM> is maintained in a state of being unwound by a length equal to or less than the second length L2 when the spiral spring <NUM> provides the constant attractive force in the state of being wound by the length equal to or less than the second length L2. Specifically, referring to (a) in <FIG>, the third frame <NUM> may be maintained in a state of being maximally moved in the first direction A with respect to the third rear portion <NUM> in the second state. The spring member <NUM> may connect the third frame <NUM> and the third rear portion <NUM> with each other in a state in which the spiral spring <NUM> is unwound by the length equal to or less than the second length L2 in the second state.

<FIG> is a front view of some components of a mobile terminal according to one embodiment. Specifically, (a) in <FIG> is a view corresponding to the first state of the mobile terminal, and (b) in <FIG> is a view corresponding to the second state of the mobile terminal.

The third rear portion <NUM> may include a slit 1029b communicating the rear face and the front face of the third rear portion <NUM> with each other such that the spiral spring <NUM> is disposed on the front face of the third rear portion <NUM>.

The spring member <NUM> may be disposed such that the fixed shaft <NUM> is fixed to the third rear portion <NUM> and the end of the spiral spring <NUM> is fixed to the third frame <NUM> and unwound in the first direction. Specifically, the third frame <NUM> may include an engaging portion <NUM> protruding in the rear face direction, and the engaging portion <NUM> may be disposed to penetrate the slit 1029b. The spiral spring <NUM> may be disposed to be wound around or unwound from the fixed shaft <NUM> fixed to the third rear portion <NUM>, and the end of the spiral spring <NUM> may be fixed to the engaging portion <NUM> disposed on the third frame <NUM>.

<FIG> is a cross-sectional view of some components of a mobile terminal according to one embodiment. Specifically, (a) in <FIG> illustrates a cross-section taken along a line E-E' in <FIG>, and <FIG> in <FIG> illustrates a cross-section taken along a line F-F' in <FIG>.

When the fixed shaft <NUM> of the spring member <NUM> is fixed to the third frame <NUM>, the third rear portion <NUM> may include the guide groove 1029a as a space along which the spring member <NUM> moves. The guide groove 1029a may be defined along the first direction A.

When the fixed shaft <NUM> of the spring member <NUM> is fixed to the third rear portion <NUM>, the third rear portion <NUM> may include the slit 1029b penetrating the front face and the rear face of the third rear portion <NUM>. The slit 1029b may be defined along the first direction A.

<FIG> is a rear face view of some components of a mobile terminal according to one embodiment. <FIG> is a cross-sectional view taken along a line G-G' in <FIG>. <FIG> is a view for describing some components of a mobile terminal according to one embodiment. Hereinafter, a description will be given focusing on a difference from <FIG>.

In the mobile terminal <NUM> according to an embodiment, the spring member <NUM> may be disposed differently from <FIG>. As a fixed shaft of the spring member <NUM>, a shaft 1028a of the first roller <NUM> may be used. Specifically, the spiral spring <NUM> may be wound around or unwound from the shaft 1028a of the first roller <NUM>.

The spiral spring <NUM> may be disposed to surround the shaft 1028a of the first roller <NUM> and may be disposed to be unwound in the second direction B, which is opposite to the first direction A. The spiral spring <NUM> may be fixed directly to the third frame <NUM> or may be connected to the third frame <NUM> through a connector.

In order for the spiral spring <NUM> to be fixed directly to the third frame <NUM>, the spiral spring <NUM> is necessary to be fixed to the third frame <NUM> in a state of being maximally unwound from the shaft 1028a of the first roller <NUM> in the first state. This is because the third frame <NUM> is spaced apart from the first roller <NUM> in the second direction B in the first state. In this case, the spiral spring <NUM> may be maintained in a state of being maximally wound around the shaft 1028a of the first roller <NUM> in the second state. However, the spiral spring <NUM> may be disposed to be wound and unwound by a length between the first length L1 and the second length L2.

In order for the spiral spring <NUM> to be fixed indirectly to the third frame <NUM>, the spring member <NUM> may additionally include a wire <NUM> for connecting the end of the spiral spring <NUM> with the third frame <NUM>, and a shaft <NUM> that is fixed to the third rear portion <NUM> and surrounded by the wire <NUM> such that both ends of the wire <NUM> are directed in the first direction A. In this case, the spiral spring <NUM> may be maintained in the state of being maximally wound around the shaft 1028a of the first roller <NUM> in the first state, and maintained in the state of being maximally unwound from the shaft 1028a of the first roller <NUM> in the second state.

The shaft <NUM> may further include a bearing <NUM> that rotates in response to the movement of the wire <NUM>. This is to prevent a force required to move the second frame <NUM> from increasing due to friction between the wire <NUM> and the shaft <NUM>.

The first roller <NUM> may be divided into two regions. A first region may be a region that rotates in contact with the rear face of the flexible display panel <NUM>. A second region may be a region around which the spiral spring <NUM> is wound. In this case, a diameter of the second region may be smaller than a diameter of the first region.

In addition, the first roller <NUM> may rotate in the first region and may not rotate in the second region. The second region may be a region where the shaft 1028a of the first roller <NUM> is exposed, and the first region may be a region including a component that rotates on the shaft 1028a of the first roller <NUM>. In some cases, the shaft 1028a of the first roller <NUM> may also rotate.

Claim 1:
A mobile terminal comprising:
a first frame (<NUM>);
a second frame (<NUM>) including a third rear portion (<NUM>) coupled to a rear face of the first frame (<NUM>) and being movable in a first direction, and including a first roller (<NUM>) disposed at an end in the first direction of the third rear portion (<NUM>);
a third frame (<NUM>) coupled to a rear face of the third rear portion being movable in the first direction;
a flexible display panel (<NUM>) surrounding the first roller (<NUM>) and having one end on a front face of the first frame (<NUM>) and another end disposed on the third frame (<NUM>);
a driving unit (<NUM>) configured to drive the second frame (<NUM>) from the first frame (<NUM>) in the first direction or in a second direction reverse to the first direction; and
a spring member (<NUM>) connecting the third frame to the third rear portion (<NUM>) of the second frame (<NUM>) and configured to provide a constant force in the second direction to the third frame,
wherein the spring member (<NUM>) includes:
a fixed shaft (<NUM>), wherein the fixed shaft (<NUM>) is a shaft (1028a) of the first roller;
a spiral spring (<NUM>) wound around or unwound from the fixed shaft (<NUM>),
a wire (<NUM>) connecting an end of the spiral spring (<NUM>) to the third frame; and
a shaft (<NUM>) fixed to the third rear portion (<NUM>) and surrounded by the wire (<NUM>) such that both ends of the wire are directed in the first direction and wherein the spiral spring (<NUM>) is configured to generate a constant attractive force while being wound around or unwound from the fixed shaft (<NUM>).