Patent Description:
Conventional mobile devices often focus on the requirements of portability, lightness, and thinness. As a result, the size of the display screen of the mobile device is limited. However, with the development of mobile devices, users' demand for large-size display screens has increased rapidly. Therefore, many related products that can expand the size of the display screen have been published in recent years, that is, the display screen area can be increased when the mobile device is used but still meet the requirements of light and thin when the mobile device is carried and stored. <CIT> gives an example for such a mobile device that can be expanded and retracted by telescopic sliding.

However, during the transition between the unfolded and retracted states of the foldable flexible display screen, the tensile stress or the material fatigue may easily lead to creases, damages, or cracks in the flexible display screen.

Therefore, a main objective of the present invention is to provide a mobile device with a retractable display screen, which can be selectively switched between the outstretched and retracted states according to the needs during use.

An objective of the present invention is to provide a retractable screen mobile device. The retractable screen mobile device comprises a main unit, a movable unit, at least one elastic member, a flexible display screen, and at least one constant force spring. The main unit includes a first shell, a first supporting element, and an accommodating space, wherein the first supporting element is disposed on the first shell and has a first supporting surface, and the accommodating space is surrounded and defined by the first shell and the first supporting element. The movable unit is slidably disposed on the main unit along a telescopic axis and being capable of converting between a retracted state and an outstretched state with respect to the main unit. The moveable unit includes a frame, a pivot shaft, at least one hook, a second supporting element, a steering shaft, and a moving plate, wherein the pivot shaft is disposed on one side of the frame away from the first shell, the at least one hook is pivotally hung on the pivot shaft, the second supporting element is pivotally connected to the at least one hook and has a second supporting surface, the second supporting element is able to switch between a lower position and an aligned position with respect to the pivot shaft, the steering shaft is connected to the frame and accommodated in the accommodating space, and the moving plate partially covers the first shell. The at least one elastic member with two ends respectively disposed on the first shell and the moving plate, and tends to keep the movable unit in either the retracted state or the outstretched state. The flexible display screen includes a first end and a second end, wherein the first end is disposed on the first supporting element and the second end is fixed to the first shell, and wherein the flexible display screen covers the first supporting surface, winds around the pivot shaft to change direction, and winds around the steering shaft to change direction again. The at least one constant force spring includes a winding part and a telescopic part, wherein the winding part is disposed on the first shell, and the telescopic part is disposed on the frame for constantly providing a pulling force on the frame, so that the steering shaft disposed on the frame constantly tightens the flexible display screen. The pivot shaft and the first shell are closest to each other when the movable unit is in the retracted state, and the pivot shaft and the first shell are farthest away from each other when the movable unit is in the outstretched state.

In one embodiment, when the movable unit is in the retracted state, the second supporting element is in the lower position, partially accommodated in the accommodating space and partially overlapped with the first supporting element, the first supporting surface and the second supporting surface are not coplanar, and the flexible display screen is mainly supported by the first supporting surface. When the movable unit is in the outstretched state, the second supporting element is in the aligned position, the first supporting element and the second supporting element do not overlap to each other, the first supporting surface and the second supporting surface are substantially coplanar, and the flexible display screen is jointly supported by the first supporting surface and the second supporting surface.

In one embodiment, the movable unit further includes at least one compression spring, which is disposed on the frame and abuts against the second supporting element, and provides a supporting force on the second supporting element. The at least one compression spring makes the second supporting element tend to approach the first supporting element when the movable unit is in the retracted state The at least one compression spring supports the second supporting element and makes the first supporting element and the second supporting element be coplanar to jointly support the flexible display screen when the movable unit is in the outstretched state.

In one embodiment, the flexible display screen winds with a Z-shaped section, and has a display area, a first inward area, and a second inward area, wherein the display area is located between the first end of the flexible display screen and the pivot shaft, the first inward area is located between the pivot shaft and the steering shaft, and the second inward area is located between the steering shaft and the second end of the flexible display screen. When the movable unit changes from the retracted state to the outstretched state with respect to the main unit, an area of the display area gradually increases, an area of the first inward area remains unchanged, and an area of the second inward area gradually decreases.

In one embodiment, the second supporting element includes a main plate, two wing plates, two abutting parts, and at least one pivot part, wherein the wing plates are disposed respectively on both sides of the main plate and fixed on the frame, and the abutting parts are respectively disposed on the wing plates, opposite to and substantially parallel to the main plate, and are abutted by the at least one compression spring. The second supporting element is pivotally connected to the at least one hook.

In one embodiment, the first supporting element further has a first inner surface and a first inclined surface, wherein the first inner surface is opposite to the first supporting surface, and the first inclined surface connects the first supporting surface and the first inner surface. The second supporting element further has a second inner surface and a second inclined surface, wherein the second inner surface is opposite to the second supporting surface, and the second inclined surface connects the second supporting surface and the second inner surface. The first inclined surface and the second inclined surface are matched and substantially abutted against with each other when the movable unit is in the outstretched state.

In one embodiment, a first inner acute angle is formed between the first supporting surface and the first inclined surface, a first inner obtuse angle is formed between the first inner surface and the first inclined surface, a second inner obtuse angle is formed between the second supporting surface and the second inclined surface, and a second inner acute angle is formed between the second inner surface and the second inclined surface.

In one embodiment, the first shell includes a main body and a fixing plate. The fixing plate is disposed on the main body and has at least one displacement guide body The at least one displacement guide body has a first positioning section, a panning section, a lifting section, and a second positioning section in sequence. The second supporting element further includes at least one moving guide, which is disposed on the wing plates corresponding to the at least one displacement guide body and abuts against the at least one displacement guide body. When the movable unit is in the retracted state, the at least one moving guide is positioned at the first positioning section. When the movable unit is moved out of the retracted state, the at least one moving guide slides along the panning section. When the movable unit is converted from the retracted state to the outstretched state, the at least one moving guide slides from the panning section to the lifting section for lifting the second supporting element until the at least one moving guide is positioned at the second positioning section, and the movable unit is in the outstretched state.

In one embodiment, the movable unit further includes two guide pieces, each of the wing plates has a guide groove, and the guide pieces respectively slide in the corresponding guide grooves.

In one embodiment, the second end of the flexible display screen is fixed on the fixing plate. When the movable unit is in the outstretched state, the display area is supported by the first supporting surface and the second supporting surface and is partially wound around the pivot shaft. When the movable unit is in the retracted state, the display area is supported by the first supporting surface and is partially wound around the pivot shaft. When the movable unit is in either the retracted state or the outstretched state, the first inward area and the second inward area are accommodated in the accommodating space.

In one embodiment, the moving plate has a cover and a sliding part, the fixing plate has at least one hollow part and a fixing portion, the at least one elastic member is accommodated in the at least one hollow part and has a first end part and a second end part, the first end part is disposed on the fixing portion, and the second end part is disposed on the sliding part. When the movable unit is in the retracted state, the second end part is located away from the pivot shaft relative to the first end part, and tends to push the sliding part away from the pivot shaft thus to remain in the retracted state. When the movable unit is in the outstretched state, the second end part is located closer to the pivot shaft relative to the first end part, and tends to push the sliding part towards the pivot shaft thus to remain in the outstretched state.

In one embodiment, the sliding part further has at least one sliding protrusion, the fixing plate further has at least one sliding groove extending along the telescopic axis. The at least one sliding protrusion corresponds to and engages with the at least one sliding groove. When the movable unit moves relative to the main unit, the at least one sliding protrusion moves along the at least one sliding groove.

In one embodiment, the pivot shaft is a damping shaft, which provides a damping force when the movable unit moves relative to the main unit.

In one embodiment, the damping shaft has a hollow outer tube, an inner tube, a filling area, a damping oil, and two oil seals. The inner tube passes through the hollow outer tube and two ends of the inner tube are respectively fixed on the frame. The hollow outer tube rotates relative to the inner tube. The filling area is formed between the hollow outer tube and the inner tube. The damping oil is filled in the filling area. The oil seals are respectively disposed on both ends of the filling area to seal the damping oil in the filling area.

In one embodiment, the pivot shaft has a rod body and at least one hook recess. The rod body is disposed along a steering axis that is substantially perpendicular to the telescopic axis. The at least one hook recess is formed on the rod body for the at least one hook part hanging thereon.

Reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings, and are not intended to limit the present invention, applications or implementations described in these embodiments. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. It shall be appreciated that, in the following embodiments and the attached drawings, elements unrelated to the present invention are omitted from depiction; and dimensional relationships among individual elements in the attached drawings are provided only for ease of understanding, but not to limit the actual scale.

The present invention relates to a retractable screen mobile device <NUM> as shown in <FIG> and <FIG> in a retracted state and an outstretched state, respectively, and in an exploded view in <FIG>. The retractable screen mobile device <NUM> primarily comprises a main unit <NUM>, a movable unit <NUM>, two elastic members <NUM>, a flexible display screen <NUM>, and two constant force springs <NUM>. Referring to <FIG>, the main unit <NUM> comprises a first shell <NUM>, a first supporting element <NUM>, and an accommodating space <NUM>. The first supporting element <NUM> is roughly plate-shaped and is disposed on the first shell <NUM> and surrounds the accommodating space <NUM> in conjunction with the first shell <NUM>. The first shell <NUM> comprises a main body <NUM>, a fixing plate <NUM>, two hollow parts <NUM>, and two sliding parts <NUM>. The main body <NUM> has two bases <NUM>, two first hollow areas <NUM>, and two first sliding areas <NUM>. The fixing plate <NUM> is disposed on the main body <NUM> and has two interspaced displacement guide bodies <NUM>, two second hollow areas <NUM>, two fixing portions <NUM>, two second sliding areas <NUM>, and two locking portions <NUM>. Each displacement guide body <NUM> has a first positioning section <NUM>, a panning section <NUM>, a lifting section <NUM>, and a second positioning section <NUM> in sequence. The first hollow area <NUM> and the second hollow area <NUM> correspond to each other and overlap to form the hollow parts <NUM>. The first sliding area <NUM> and the second sliding area <NUM> correspond to each other and overlap to form the sliding part <NUM>. The locking portion <NUM> fixes one end of the flexible display screen <NUM>.

In detail, referring to the enlarged portion of the first supporting element <NUM> shown in <FIG>, the first supporting element <NUM> has a first supporting surface <NUM>, a first inner surface <NUM>, a first inclined surface <NUM>, a first inner acute angle <NUM>, and a first inner obtuse angle <NUM>. The first inclined surface <NUM> connects the first supporting surface <NUM> and the first inner surface <NUM>, and the first inner acute angle <NUM> is formed between the first supporting surface <NUM> and the first inclined surface <NUM>, and the first inner obtuse angle <NUM> is formed between the first inner surface <NUM> and the first inclined surface <NUM>.

Additionally, the main unit <NUM> also includes a panel body (not shown in the figure) electrically connected to the flexible display screen <NUM>, i.e. a module of electronic components such as a circuit board or battery, to provide corresponding functions for the mobile device. Further details are not discussed here.

The movable unit <NUM> is disposed on the main unit <NUM> and can be outstretched and retracted relative to the main unit <NUM> along a telescopic axis A1 between a retracted state (<FIG>) and an outstretched state (<FIG>).

In detail, as shown in <FIG>, the movable unit <NUM> includes a frame <NUM>, a pivot shaft <NUM>, three hooks <NUM>, a second supporting element <NUM>, a steering shaft <NUM>, a moving plate <NUM>, two compression springs <NUM> (referring to <FIG>), and two guide pieces <NUM>. The frame <NUM> has an arc-shaped panel <NUM> and two sliding side panels <NUM>. The arc-shaped panel <NUM> is disposed on one side away from the first shell <NUM> and the sliding side panels <NUM> are correspondingly disposed at both ends of the arc-shaped panel <NUM> (i.e., they form a U-shape together), and the pivot shaft <NUM> is pivotally connected to it. The pivot shaft <NUM> is a damping shaft, with both ends pivotally disposed on the sliding side panels <NUM> correspondingly, away from the first shell <NUM>, and having a rod body <NUM> and three hook recesses <NUM>. The rod body <NUM> is disposed along a steering axis A2 which is substantially perpendicular to the telescopic axis A1.

According to the cross-sectional view of the pivot shaft <NUM> shown in <FIG>, the pivot shaft <NUM> has a hollow outer tube <NUM>, an inner tube <NUM>, a filling area <NUM>, a damping oil <NUM>, and two oil seals <NUM>. The inner tube <NUM> is inserted into the hollow outer tube <NUM>, and the two ends of the inner tube <NUM> are fixed to the frame <NUM>. The hollow outer tube <NUM> and the inner tube <NUM> can rotate relative to each other. The filling area <NUM> is formed between the hollow outer tube <NUM> and the inner tube <NUM>, and the damping oil <NUM> is filled in the filling area <NUM>. The oil seals <NUM> are respectively set at both ends of the filling area <NUM> to seal the damping oil <NUM> in the filling area <NUM>. When the hollow outer tube <NUM> rotates relative to the inner tube <NUM>, the damping oil <NUM> provides a damping force.

The hooks <NUM> are pivotally connected to the second supporting element <NUM> and are correspondingly hung on the three hook recesses <NUM> of the pivot shaft <NUM> respectively to pivot relative to the pivot shaft <NUM>.

Refer to <FIG> (partially enlarged view) and <FIG> (three-dimensional illustration) for more details. The second supporting element <NUM> has a main plate <NUM>, two wing plates <NUM>, two abutting parts <NUM>, three pivot parts <NUM>, a moving guide <NUM>, a second supporting surface <NUM>, a second inner surface <NUM>, a second inclined surface <NUM>, a second inner acute angle <NUM>, and a second inner obtuse angle <NUM>. The second supporting element <NUM> is hung on the pivot shaft <NUM> via the hooks <NUM> and can pivot relative to the hooks <NUM>. It can pivot between a lower position (<FIG>) and an aligned position (<FIG>).

The wing plates <NUM> are respectively arranged on both sides of the main plate <NUM> and extend perpendicular to the main plate <NUM>. They are fixed to the frame <NUM> and each has a guide groove <NUM>. The abutting parts <NUM> are respectively arranged on the side of the wing plates <NUM> adjacent to each other and extend substantially parallel to the main plate <NUM>, and abut against the compression spring <NUM>. The second supporting element <NUM> is connected to the hooks <NUM> through the pivot parts <NUM>.

Specifically, the moving guide <NUM> is disposed on the wing plate <NUM> corresponding to the displacement guide body <NUM> on the first shell <NUM> and abuts against the displacement guide body <NUM>. As shown in <FIG>, the moving guide <NUM>, for example, is a roller, when the movable unit <NUM> is in the retracted state, the moving guide <NUM> is located in the first positioning section <NUM>, causing the second supporting element <NUM> to be positioned at the lower position. When the movable unit <NUM> is moved out of the retracted state, the moving guide <NUM> slides along the panning section <NUM>. When the movable unit <NUM> departs from the retracted state and switches to the outstretched state, the moving guide <NUM> slides from the panning section <NUM> to the lifting section <NUM> to lift the second supporting element <NUM>, until the moving guide <NUM> is positioned in the second positioning section <NUM>, the second supporting element <NUM> switches to the aligned position as shown in <FIG>, with the movable unit <NUM> in the outstretched state.

Furthermore, referring to <FIG>, the second inner surface <NUM> is opposite to the second supporting surface <NUM>, the second inclined surface <NUM> connects the second supporting surface <NUM> and the second inner surface <NUM>, and there is a second inner obtuse angle <NUM> formed between the second supporting surface <NUM> and the second inclined surface <NUM>, and a second inner acute angle <NUM> formed between the second inner surface <NUM> and the second inclined surface <NUM>. The first inner acute angle <NUM> and the second inner obtuse angle <NUM> are complementary, and the first inner obtuse angle <NUM> and the second inner acute angle <NUM> are complementary. As a result, the transformation between the second supporting element <NUM> in the lower position and the aligned position can be smoother.

The steering shaft <NUM> is connected at both ends to the frame <NUM> and disposed within the accommodating space <NUM>, with the moving plate <NUM> partially covering the first shell <NUM>.

Specifically, the moving plate <NUM> has a cover <NUM> and a sliding part <NUM>. The sliding part <NUM> further has two sliding protrusions <NUM>, respectively corresponding to and engaging with the sliding parts <NUM> of the first shell <NUM>. When the movable unit <NUM> moves relative to the main unit <NUM>, the sliding protrusions <NUM> move along the sliding parts <NUM>. As shown in <FIG>, when the movable unit <NUM> is in the retracted state, the sliding protrusions <NUM> are respectively located at a first stopping end <NUM> of the sliding parts <NUM>, and as shown in <FIG>, when the movable unit <NUM> is switched to the outstretched state, the sliding protrusions <NUM> are respectively located at a second stopping end <NUM> of the sliding part <NUM>.

The compression spring <NUM> is disposed on the frame <NUM> and abuts against the abutting part <NUM> of the second supporting element <NUM>. The compression spring <NUM> continuously provides support to the second supporting element <NUM>. As shown in <FIG>, in the retracted state, the compression spring <NUM> causes the second supporting element <NUM> to be inclined towards the first supporting element <NUM>. As shown in <FIG>, in the outstretched state, the compression spring <NUM> supports the second supporting element <NUM> (i.e., the compression spring <NUM> continuously tends to provide upward support) and maintains the second supporting element <NUM> in a plane with the first supporting element <NUM>, together supporting the flexible display screen <NUM> (<FIG>).

Referring to <FIG> and <FIG>, the guide pieces <NUM> are disposed on the moving plate <NUM> and each has a guide post <NUM>. The guide post <NUM> corresponds to the guide groove <NUM> and can slide within the guide groove <NUM>. As shown in <FIG>, when the second supporting element <NUM> is at the lower position, the guide post <NUM> is at the first end portion <NUM> of the guide groove <NUM>, and as shown in <FIG>, when the second supporting element <NUM> is at the aligned position, the guide post <NUM> is at the second end portion <NUM> of the guide groove <NUM>, in order to restrict the movement path of the second supporting element <NUM> during conversion between the lower position and the aligned position, and to ensure that the second supporting element <NUM> will not exceed the aligned position due to the upward support force provided by the compression spring <NUM>.

Referring to <FIG> and <FIG>, the elastic member <NUM> is a torsion spring, which comprises a first end part <NUM> and a second end part <NUM>. The elastic members <NUM> are disposed in the hollow parts <NUM>. The first end part <NUM> is fixed to the fixing portion <NUM> of the first shell <NUM> of the main unit <NUM>. The second end part <NUM> is fixed to the sliding part <NUM> of the moving plate <NUM> of the movable unit <NUM>. The elastic members <NUM> can assist the movable unit <NUM> to convert between the retracted state and the outstretched state.

As shown in <FIG>, when the movable unit <NUM> is in the retracted state, the elastic member <NUM> tends to cause the movable unit <NUM> to remain in the retracted state. However, when it is desired to convert to the outstretched state, an external force is required to push the movable unit <NUM> and overcome the elasticity provided by the elastic member <NUM>, causing the movable unit <NUM> to depart from the retracted state and gradually move away from the main unit <NUM>. After the movable unit <NUM> moves a certain distance relative to the main unit <NUM>, the elastic member <NUM> provides the elasticity to bring the movable unit <NUM> to the outstretched state, as shown in <FIG>, and causes the movable unit <NUM> to tend to remain in the outstretched state. Further, during the conversion between the retracted state and the outstretched state, the first end part <NUM> is fixed to the fixing portion <NUM>, so it is relatively immovable, while the second end part <NUM> is attached to the sliding part <NUM>. In the retracted state shown in <FIG>, the second end part <NUM> is located on one side (i.e., the right side) of the first end part <NUM>, distant from the pivot shaft <NUM>, and tends to push the sliding part <NUM> away from the pivot shaft <NUM>, thus tending to remain in the retracted state. In the outstretched state shown in <FIG>, the second end part <NUM> is relative to the first end part <NUM> near one side (i.e. the left side) of the pivot shaft <NUM>, and tends to push the sliding part <NUM> towards the pivot shaft <NUM>, thus tending to maintain in the outstretched state. In other embodiments, the elastic member <NUM> may each be a serpentine spring, which may provide the same effect.

Reference is made to <FIG> and <FIG>. The flexible display screen <NUM> includes a first end <NUM>, a second end <NUM>, a display area <NUM>, a first inward area <NUM>, and a second inward area <NUM>. The first end <NUM> is positioned on the first supporting element <NUM>, and the flexible display screen <NUM> covers the first supporting surface <NUM> and deflects (changes direction) around the pivot shaft <NUM> and deflects (changes direction) again around the steering shaft <NUM>, while the second end <NUM> is fixed on the locking portion <NUM> of the first shell <NUM>, so the flexible display screen <NUM> winds and presents a roughly Z-shaped mirror cross-section (from the other side view of <FIG>, it is a Z-shaped cross-section). Specifically, the display area <NUM> is between the first end <NUM> of the flexible display screen <NUM> and the pivot shaft <NUM>, the first inward area <NUM> is between the pivot shaft <NUM> and the steering shaft <NUM>, and the second inward area <NUM> is between the steering shaft <NUM> and the second end <NUM> of the flexible display screen <NUM>. When the movable unit <NUM> changes from the retracted state (<FIG>) to the outstretched state (<FIG>) relative to the main unit <NUM>, the flexible display screen <NUM> undergoes dynamic changes, but the area of the first inward area <NUM> remains unchanged, while the area of the display area <NUM> gradually increases and the area of the second inward area <NUM> gradually decreases (approximately, the increase in the area of the display area <NUM> is equal to the decrease in the area of the second inward area <NUM>). Conversely, when the movable unit <NUM> changes from the outstretched state (<FIG>) to the retracted state (<FIG>) relative to the main unit <NUM>, the area of the first inward area <NUM> remains unchanged, while the area of the display area <NUM> gradually decreases and the area of the second inward area <NUM> gradually increases.

In other words, in the outstretched state, the display area <NUM> is supported by the first supporting surface <NUM> and the second supporting surface <NUM> and partially wrapped around the pivot shaft <NUM>, and in the retracted state, the display area <NUM> is supported by the first supporting surface <NUM> and partially wrapped around the pivot shaft <NUM>. In both the retracted state and the outstretched state, the first inward area <NUM> and the second inward area <NUM> are constantly accommodated within the accommodating space <NUM>.

As shown in <FIG> and <FIG>, the constant force spring <NUM> each includes a winding part <NUM> and a telescopic part <NUM>. The winding part <NUM> is located on the base <NUM> of the first shell <NUM>, and the telescopic part <NUM> is fixed on the frame <NUM> for constantly providing the frame <NUM> with a tension force in the direction towards the first shell <NUM> along the telescopic axis A1, so that the steering shaft <NUM> located on the frame <NUM> constantly tightens the flexible display screen <NUM>.

Specifically, as shown in <FIG>, <FIG>, <FIG>, <FIG>, <FIG>, when the movable unit <NUM> is in its retracted state, the pivot shaft <NUM> is closest to the first shell <NUM>, the second supporting element <NUM> is located at its lower position and is disposed in the accommodating space <NUM>, partially overlapping with the first supporting element <NUM>. At this time, the first supporting surface <NUM> and the second supporting surface <NUM> are not coplanar and the flexible display screen <NUM> is primarily supported by the first supporting surface <NUM>. Furthermore, when the second supporting element <NUM> is at its lower position, the moving guide <NUM> is located in the first positioning section <NUM> and the compression spring <NUM> are compressed by the second supporting element <NUM>, and the area of the display area <NUM> of the flexible display screen <NUM> is minimized, and the area of the second inward area <NUM> is maximized. Additionally, as shown in <FIG>, when the movable unit <NUM> is in its retracted state, the sliding protrusions <NUM> is located at the first stopping end <NUM> of the sliding parts <NUM> and the elastic members <NUM> are compressed and disposed in the hollow parts <NUM>.

When converting the movable unit <NUM> from its retracted state to its outstretched state as illustrated in <FIG>, <FIG>, <FIG>, <FIG>, and <FIG> for increasing the display area of the flexible display screen <NUM>, the user can apply an external force to the movable unit <NUM> to cause it to depart from its retracted state. The elastic member <NUM> provides elasticity, allowing the movable unit <NUM> to gradually move along the telescopic axis A1. As the movable unit <NUM> moves away from the first shell <NUM> along the telescopic axis A1, the moving guide <NUM> of the second supporting element <NUM> moves along the panning section <NUM>, and the steering shaft <NUM> gradually moves away from the first end <NUM> of the flexible display screen <NUM> and towards the second end <NUM>, thus increasing the display area <NUM> and decreasing the second inward area <NUM> while maintaining the first inward area <NUM> unchanged. The telescopic part <NUM> of the constant force spring <NUM> is stretched as the steering shaft <NUM> gradually moves away, providing a pulling force that tightens the flexible display screen <NUM>. The sliding protrusion <NUM> slides in the sliding part <NUM> from the first stopping end <NUM> to the second stopping end <NUM>.

Subsequently, when the moving guide <NUM> moves from the panning section <NUM> to the lifting section <NUM> and then to the second positioning section <NUM>, the second supporting element <NUM> is lifted, and at the same time, the compression spring <NUM> provides an elastic force to the second supporting element <NUM>, causing the second supporting element <NUM> to slightly pivot around the pivot shaft <NUM>, so that the second supporting element <NUM> is aligned with the first supporting element <NUM>, as shown in <FIG>, with the second supporting surface <NUM> and the first supporting surface <NUM> forming a common plane and supporting the display area <NUM> of flexible display screen <NUM>. At this time, the area of the display area <NUM> of the flexible display screen <NUM> is at its maximum, and the area of the second inward area <NUM> is at its minimum. Furthermore, as shown in <FIG>, when the movable unit <NUM> is in the outstretched state, the sliding protrusion <NUM> is located at the second stopping end <NUM> of the sliding part <NUM>.

Furthermore, since the pivot shaft <NUM> is a damping shaft, when the movable unit <NUM> slides reciprocally relative to the main unit <NUM>, the pivot shaft <NUM> provides a damping force to prevent the movement of the movable unit <NUM> relative to the main unit <NUM> from being too fast, resulting in damage to the components, and provides a harmonious and smooth operation for the user to enhance the product quality and value. However, the pivot shaft <NUM> is not limited to a damping shaft and can also be a non-damping shaft. Additionally, if the pivot shaft <NUM> is a non-damping shaft, a damping rod (not shown in the figure) may be provided along the telescopic axis A1 to abut between the first shell <NUM> and the frame <NUM> to provide a damping effect.

Claim 1:
A retractable screen mobile device, comprising:
a main unit including a first shell, a first supporting element, and an accommodating space, wherein the first supporting element is disposed on the first shell and has a first supporting surface, and the accommodating space is surrounded and defined by the first shell and the first supporting element;
a movable unit slidably disposed on the main unit along a telescopic axis and being capable of converting between a retracted state and an outstretched state with respect to the main unit, wherein the movable unit includes a frame, a pivot shaft, at least one hook, a second supporting element, a steering shaft, and a moving plate, and wherein the pivot shaft is disposed on one side of the frame away from the first shell, the at least one hook is pivotally hung on the pivot shaft, the second supporting element is pivotally connected to the at least one hook and has a second supporting surface, the second supporting element is able to switch between a lower position and an aligned position with respect to the pivot shaft, the steering shaft is connected to the frame and accommodated in the accommodating space, and the moving plate partially covers the first shell;
at least one elastic member with two ends respectively disposed on the first shell and the moving plate, and tends to keep the movable unit in either the retracted state or the outstretched state;
a flexible display screen including a first end and a second end, wherein the first end is disposed on the first supporting element and the second end is fixed to the first shell, and wherein the flexible display screen covers the first supporting surface, winds around the pivot shaft to change direction, and winds around the steering shaft to change direction again; and
at least one constant force spring including a winding part and a telescopic part, wherein the winding part is disposed on the first shell, and the telescopic part is disposed on the frame for constantly providing a pulling force on the frame, so that the steering shaft disposed on the frame constantly tightens the flexible display screen;
wherein the pivot shaft and the first shell are closest to each other when the movable unit is in the retracted state, and the pivot shaft and the first shell are farthest away from each other when the movable unit is in the outstretched state.