Patent Description:
Flexible and especially rollable displays are manufactured on an organic substrate and are very thin. This makes it possible to repeatedly bend them with a small radius, a requirement for a rollable display. The advantages of a rollable display are the small volume needed for storing in the closed position and the lack of glass making the display unbreakable and of light weight.

A number of product concepts have been developed for flexible displays. The most important concepts are the 'book', the 'wrap' and the 'roll'.

The 'book' concept is the simplest implementation of a rollable display comprising two hingeably connected support halves with a continuous display. In the middle near the hinge mechanism is a hollow space to accommodate the curved segment of the display in the situation where the 'book' is in the closed position. The display size is at most twice the size of the closed display system. In practice, it will be around <NUM>. 8x the size due to the bezel of the support halves needed around the display.

The 'wrap' concept comprises a display, wrapped with its front side to the inside.

Thus the display is protected when the 'wrap' is in the closed position. The display currently makes one complete turn around the device body when wrapped. Therefore, the size of the display will be about twice the size of the device. For larger displays compared to the device body more turns are required, which adds mechanical complexity.

In these 'book' or 'wrap' concepts with hinge constructions in the connection of the support halves, the display is fixed at either end at the support halves. The flexible display in such display systems may interfere in two ways with the hinge constructions (in either the open or closed position). First in a literal sense. In concepts where the hinge constructions are directly below or behind the display there may not be enough space to create a functional hinge. Secondly, normally the freedom of position (relative to the display) of the hinge pins is also limited, because their relative position to the display needs to be taken into account in open as well as closed position. While flexing, the curvature of the display should not exceed a certain value, as this will result in damage to the display. Often, this flexed shape takes quite a bit of room and the construction of the device and especially the position of the hinge pin(s) must provide enough space to allow the display to do this.

Basically, often there is not enough space for the hinge construction or the hinge(s) would need to be positioned in a way that would not be desirable from a product design point of view.

Since the backside of the display in the hinge area between the display supports is less suitable to be connected with stiff parts, at the unsupported parts of the display in this area the backside and the lateral sides become vulnerable to damage in the open position. This can result in special problems when touch functionality has to be integrated into the display.

It is an object of the invention to increase the design freedom for hinge constructions and their positioning in such a display system with a continuous flexible display.

<CIT> discloses an electronic device that includes a main body and a flexible display panel. The main body includes a body portion, a connecting portion, and a cover portion. The connecting portion is pivotally connected to the body portion. The cover portion is pivotally connected to the connecting portion so as to be capable of rotating relative to the body portion. The cover portion, the body portion, and the connecting portion form a containing space cooperatively. The flexible display panel is disposed in the containing space in a curved manner. The flexible display panel includes a first display section and a second display section. The first display section is fixed to the cover portion. The second display section is slidably disposed on the body portion.

<CIT> discloses a flip-type mobile communication terminal including a first main body, a second main body coupled to the first main body; a flexible display; a connection member connected to the flexible display; and a length-adjusting assembly to adjust the length of the flexible display.

<CIT> discloses a foldable electronic device that includes a foldable casing and a flexible display. The flexible display is disposed in the foldable casing, and is connected to the foldable casing through an elastic member, and the elastic member provides the flexible display the extending flexibility when being unfolded or folded together with the foldable casing.

<CIT> discloses an electronic device having a windable screen that includes a flexible screen, a first chassis and a second chassis. The flexible screen has a windable free portion at an upper side that has a first anchor structure and a fastening portion at a lower side to be fastened to the first chassis. The first chassis has a plane to flatly hold and anchor the fastening portion of the flexible screen. The second chassis has at least one operation interface and a second anchor structure which is incorporated with the first anchor structure to wind and anchor the flexible screen.

<CIT> discloses a case for supporting a foldable display panel that includes a first main body located to correspond to a first area of the foldable display panel; a second main body located to adjoin the first main body and correspond to a second area of the foldable display panel, and folded in a direction of the first main body so that the second area of the foldable display panel faces the first area; and a mover, responsive to an elastic restitution force, located within at least the first main body to be supported by a rear surface of the foldable display panel, at least one of the first area and the second area of the foldable display panel being slidable in conjunction with the mover in a direction of at least one an end of the foldable display panel.

<CIT> discloses hybrid hinges used for rotatably adjoining segments of a suitable electronic apparatus. The hybrid hinges comprise rigid hinges arranged to rotate the segments about respective shafts. The hybrid hinges further comprise respective elastic hinges having respective portions.

<CIT> relates to a multi-folding electronic device. An elastic hinge unit is provided with an elastic parallel biaxial hinge structure where subjects to be interconnected are greatly varied in their distance and operating direction while the friction resistance of axial holes is kept low to prevent turnability from being hindered so as to eliminate the need to give tolerance to the axial holes to keep their connection loose.

<CIT> discloses a portable communication apparatus that includes a first unit having at least a display section and a second unit having at least a main operation section, which are coupled by a slide coupling and are freely slidable in a longitudinal direction between a retracted state and an extended state. The first unit and the second unit are urged by an urging member in an extension direction and are releasably locked by a releasable lock mechanism in the retracted state. The locking is released by a predetermined operation.

<CIT> discloses a communications device having a spring mechanism for forcing open a sliding keypad cover. The spring mechanism comprises at least one guide rod, and an end of each guide rod is attached to the backside mechanics of the sliding keypad cover, each guide rod having a travel limit. The spring mechanism further comprises a guide frame having at least one guide hole, the at least one guide hole for receiving the at least one guide rod. The improved spring mechanism further comprises a spring positioned around the guide rod and between the at least one guide hole and the travel limit, the spring having a compressed state when the sliding keypad cover is closed. The spring mechanism further comprises a release mechanism coupled with the at least one guide rod when the sliding keypad cover is in the closed position.

<CIT> discloses an electronic device including a first display panel and a casing. The first display panel has a first displaying part and a second displaying part. The first display panel includes a first bending mechanism which is disposed between the first displaying part and the second displaying part to bend or spread the first display panel. The casing has a first surface and a second surface opposite to the first surface. The casing includes a rail mechanism which is disposed on the second surface. The second displaying part is slid on the rail mechanism to shift the first display panel relatively to the casing.

The embodiments and/or clauses and/or examples of the following description which are not covered by the appended claims are considered as not being part of the present invention.

According to one aspect the disclosure provides a display system comprising a continuous flexible display, a support frame comprising first and second main display supports, coupled by a hinge mechanism with at least one hinge axis and each structurally configured to support respectively a first and a second portion of the flexible display, the two main display supports being hingeable between a configuration for fixing the flexible display in a closed storage position and a planar configuration for fixing the flexible display in an open position, a segment of the flexible display is located between the said respective portions of the flexible display in the open position, wherein the display system comprises a spring force biased mechanism operative in either the open or closed position or both the open and closed positions of the flexible display, biasing said segment of the flexible display in the respective position.

The advantages of certain aspects of the disclosure are that by the spring force biased mechanism a construction for a display system of this kind is created enabling that the flexible display has sufficient stiffness in the extended situation, but yet occupies only a small volume in the collapsed, closed situation. Standard available hinge solutions on the market can potentially be used for the display system in accordance with the invention instead of a dedicated proprietary construction. Due to the increased space available in the hinge area more space is available for additional display support mechanisms such has described in <CIT>, later published as <CIT>.

According to a preferred embodiment of the disclosure the first portion of the flexible display is fixed to the first main display support, whereas the second portion of the flexible display is slidably mounted on the second main display support, allowing at the location of the mounting during movement of the display between the storage and open position a sliding movement of the second portion of the flexible display with respect to the second main display support in a direction substantially perpendicular to the direction of the hinge axis, the spring force biased mechanism comprises spring means located in the coupling between the second portion of the flexible display and the second main display support, biasing said segment of the flexible display in the respective position. In this embodiment the second portion of the display is fixed onto the slidable mounting, which allows a sliding in one direction. In order to keep the display flat in the open position of the device, the mounting is connected via the spring means to the second main display support.

This solution, with a spring means, causes the display in the closed position to be moved away from the hinge(s) giving more room for the hinge construction at this point. Of course some extra space is needed elsewhere in the device (in closed position) to make this possible. Another advantage is that the display in open position of the device can be pre-stretched by the spring means, thus preventing sagging of the display in the hinge area in the open position. Because of this pre-stretching, the display will also be more able to withstand touching with less deformation. Due to the pre-stretching the user will have a more consistent feeling of touch across the whole display, also in the unsupported areas.

Preferably the spring force biased mechanism comprises a slider element, the second portion of the flexible display is fixed to the slider element, which is slidably mounted on the second main display support.

In another preferred embodiment of the disclosure the hinge mechanism comprises a flexible hinge, which is part of the spring force biased mechanism and enables a freedom of movement of the hinge pin in a direction substantially parallel to the display surface in the open position. In this embodiment the hinges are moving to have "flexible" hinge axis positions. Basically the hinge pins would be mounted in an elastic substance (such as rubber). By applying the display in such a way that in open device position it would be over-stretched the hinge pin or pins will shift to accommodate the required display length. This would also provide a spring like function which could keep the display taut in the unsupported areas, while preventing too high stress in the display due to "over-stretching".

In another solution such a mechanism is applied to a 'wrap' type concept. According to another aspect of the disclosure the system comprises a continuous flexible display, a body, a support frame comprising first and second main display supports, coupled by a first hinge mechanism and each structurally configured to support respectively a first and a second portion of the flexible display, the first main display support is coupled by a second hinge mechanism with the body, the two main display supports being hingeable between a wrapped configuration around the body for fixing the flexible display in a closed storage position and a planar configuration for fixing the flexible display in an open position, a first segment of the flexible display is located near the first hinge mechanism between the said respective portions of the flexible display in the open position, a third portion of the flexible display being coupled with the body, a second segment of the flexible display is located near the second hinge mechanism between the first and third portion of the flexible display, wherein the third portion of the flexible display is slidably mounted on the body, wherein the display system comprises a spring force biased mechanism operative in either the open or closed position or both the open and closed positions of the flexible display, biasing said second segment of the flexible display in the respective position.

In this solution a slider could be applied in the device body. In this case freedom of movement would be provided for either the last hinge mechanism or for both mechanisms if the display is also slidably mounted to the first main display support.

These embodiments of the disclosure are applicable for different kinds of flexible displays, i.e. of 'wrap' or of 'book' type. The proposed solutions can be used for devices with hinge mechanisms comprising one hinge axis or more hinge axes.

Two product concepts developed for flexible displays are the 'book', the 'wrap' and the `roll'. A 'wrap' concept is shown in <CIT>, a 'book' in non-prepublished <CIT>. Later published as <CIT>.

The display system <NUM> schematically shown in <FIG> and <FIG> is a 'book' type embodiment as disclosed in the non-prepublished <CIT>, later published as <CIT>. This display system comprises a flexible display <NUM> and display support means comprising two main display supports <NUM>, <NUM>, located in book housing halves <NUM>, <NUM> respectively. The display is fixed at fixation points at the display supports <NUM>, <NUM>. Between the fixation points the display has a central segment 2a. The book halves <NUM>, <NUM> with their supports <NUM>, <NUM> are connected via two hinges <NUM>, <NUM> which are part of a hinge mechanism <NUM> and are each structurally configured to support a respective portion of the flexible display <NUM>. In order to have a flat display <NUM>, in the open position shown in <FIG> the length of the unfixed central display segment 2a needs to match the distance between the fixation points of the display. Since in the storage position of the flexible display <NUM> shown in <FIG> and <FIG> the mutual distance of these fixations points of the display at the respective supports <NUM>, <NUM> is much smaller compared with the open position, the central display segment 2a needs to flex to compensate for this reduction of distance.

Moreover, while flexing, the curvature of the display <NUM> should not exceed a certain value, as this will result in damage to the display. This flexed shape may take much room inside the housing halves <NUM>, <NUM> and the construction of these housing halves with the display supports <NUM>, <NUM> must provide enough space to allow the display segment 2a to be (partially) curved. The display should not interfere with the hinges <NUM>, <NUM> both in open and closed storage position, but also in any intermediate state, while moving between these positions.

In practice, due to the position of the hinges <NUM>, <NUM> in relation to the flexed display, also in combination with the required material thicknesses and with the required minimum radius of curvature, this results in a either a very limited freedom of the position of the hinges and/or almost no space for designing strong enough hinges.

The limitation in the positioning of the hinges <NUM>, <NUM> inside the housing halves <NUM>, <NUM> is explained by the following. In this double hinge 'book' type embodiment the distance between the fixation points of the display is determined by twice the horizontal distance (l1) to the hinge points of hinges <NUM>, <NUM> from the fixation point of the display at the main display supports <NUM>, <NUM>, plus the distance between the hinge points (l2) , e.g.: <MAT>.

Reducing the distance between the hinge points (l2) to zero would result in a single hinge 'book' type of the display system. However the calculation of the unfixed display length would still hold.

In the other extreme situation one could (theoretically) align the hinge points with the fixation points - in other words reduce the distance to the hinge points (l1) to zero. Due to the linear relationship between these extremes situations the upshot of these considerations is that the hinge points need to lie on the dotted lines a, b indicated in <FIG>. Put in another way, freedom in choosing their position is limited: <MAT>.

In accordance with the invention, by allowing one of the fixed parts of the display to slide, the position of the hinge points can be shifted.

In a first embodiment of the invention schematically shown in <FIG> the display system <NUM> has display supports <NUM>, <NUM> inside housing halves <NUM>, <NUM> which are hingeably connected by a hinge <NUM>. The display <NUM> is connected at a first display portion with the display support <NUM> in the housing halve <NUM> and the display <NUM> is fixed at a second portion onto a slider element <NUM> which is slidably mounted on the display support <NUM>. During movement from the open (<FIG>) to closed position (<FIG>) this element <NUM> allows a sliding movement on the display support in the housing halve together with the fixed display part in the direction of arrow c, i.e. in a direction substantially perpendicular to the direction of the axis of the hinge <NUM>. According to the invention, during this movement of the housing halves <NUM>, <NUM>, the display segment 2a is moved away from the hinge <NUM>, giving more room for the hinge mechanism inside the display housing at the location of the hinge <NUM> compared with the display system of <FIG>. In order to keep the display segment 2a flat after the housing halves have been moved to the open position, the display system comprises a spring force biased mechanism comprising spring means formed by a spring <NUM> connected with the slider element <NUM> and the housing halve <NUM>, said spring biases said segment 2a of the flexible display in the direction of arrow c, i.e. away from the hinge <NUM>. According to the invention, due to the location of the axis of the hinge <NUM> with respect to the display <NUM>, during movement to the open position the display becomes "over-stretched" and thus the location of the hinge in combination with the working of the spring <NUM> ensure a stable open position of the display.

As shown in <FIG> when moving to the closed position the outward movement of the slider element <NUM> by the spring <NUM> in the direction c is limited by a stop formed by an abutment <NUM> on the housing halve <NUM>.

In <FIG> an embodiment is schematically shown with a slider element <NUM>, a spring <NUM> and an abutment <NUM> which correspond with the preceding embodiment, but in this embodiment the housing halves <NUM>, <NUM> are coupled by a hinge mechanism <NUM> provided with two hinges <NUM>, <NUM>. Compared with the display system of <FIG> due to the slider element <NUM> also this double hinge embodiment shows in the closed position of <FIG> more room for the hinge mechanism <NUM> inside the display housing at the location of the hinges <NUM> and <NUM>. After movement to the flat open position the housing halves <NUM>, <NUM> are stably positioned with respect to each other in a way not shown, for example by a locking mechanism, a bi-stable spring mechanism and/or magnetic means.

In another embodiment of a 'book' concept shown in <FIG>, the segment 2a of the flexible display <NUM> is coupled with the support frame by a fixation 9a at the hinge mechanism <NUM> substantially in the middle between the first and the second portion of the flexible display. Each of the portions of the flexible display is fixed on a slider element <NUM> slidably mounted on the main display support <NUM>, <NUM> respectively, allowing at the location of each mounting during movement of the display between the closed storage and open position a sliding movement of the respective portion of the flexible display with respect to the main display support in a direction substantially perpendicular to the direction of the hinge axes of the hinges <NUM>, <NUM>. At both sides of the display a spring <NUM> is located in the coupling between the respective portion of the flexible display and the main display support, biasing said segment of the flexible display in the respective position away from the hinges <NUM>, <NUM>. Stops <NUM> are located at both display supports <NUM>, <NUM>, limiting the outward movement of respective slider element <NUM>. This embodiment with springs at both sides of the display <NUM> has the advantage of a profitable distribution of forces over the display during closing and opening, whereas in the planar open position both springs keep the display segment 2a flat. Due to the springs <NUM> and the support of the fixation 9a in the middle of the segment 2a, the segment 2a may withstand touching with less deformation. Due to the chosen dimensions and position of the fixation 9a to the hinge mechanism <NUM>, in the closed position the shape of curvature of the segment 2a is positively influenced by the fixation 9a.

It is observed that this embodiment with the two slider elements <NUM> can also be configured without the fixation 9a of the segment 2a so that the display is only connected with the slider elements <NUM>. Such a configuration has the advantage of an easy mounting of the display in the housing, whereas in the display itself a smooth transition exists between the parts supported by the slider elements and the non-supported parts of the segment 2a.

Also the embodiment shown in <FIG> , an alternative of the embodiment of <FIG> with a single hinge <NUM>, comprises two sliders <NUM>, two springs <NUM> and two stops <NUM>. In this embodiment the segment 2a of the flexible display <NUM> is not coupled the support frame. The only coupling of the display <NUM> with the support frame is via the sliders <NUM> and the springs <NUM>. In the open position of <FIG> the springs <NUM> keep the display in a position, substantially symmetric with respect to the hinge <NUM>. After being moved into the closed position the sliders <NUM> are biased by the springs <NUM> against the respective stop <NUM> enabling the segment 2a to be positioned in a well defined curvature, free from parts of the housing. Another advantage is the possibility to use identically shaped housing halves for assembling the display system <NUM>. Further advantage is that the spring force of the springs <NUM> can be limited to a comparatively low level.

An unclaimed embodiment of the display system <NUM> schematically shown in <FIG> is a 'wrap' embodiment as disclosed in <CIT>. It comprises a flexible display <NUM> and a display cover having two main display supports <NUM>, <NUM>. The first support <NUM> is connected via a hinge mechanism <NUM> provided with double hinges 25a,b to a body <NUM>, the second cover <NUM> is connected via a hinge mechanism <NUM> provided with double hinges 26a,b to the cover <NUM>. The supports <NUM> and <NUM> are each structurally configured to respectively support a first and a second portion of the flexible display <NUM>, whereas a first segment 2b of the display is located near the hinge mechanism <NUM> between the first and a third portion of the display and a second segment 2c near the hinge mechanism <NUM> between the first and second portion of the display. Due to the hinge mechanisms <NUM>, <NUM> the two main display supports <NUM>, <NUM> can be wrapped and unwrapped between a configuration shown in <FIG> for fixing the flexible display in a closed storage position and a planar configuration shown in <FIG> for fixing the flexible display in an open position. Also in this 'wrap' type embodiment a slider mechanism is applied, formed by a slider element <NUM> located in a bottom part 27a of the device body <NUM> and movable on this bottom part 27a between two end stops formed by abutments 27b and 27c. A portion of the display <NUM> is fixed at the slider element <NUM>. In this case freedom of movement would be provided for the hinge mechanism <NUM> or for both hinge mechanisms <NUM>, <NUM>, if the display is not glued to the display support <NUM>. In the storage position of the flexible display <NUM> at the location of the hinge mechanisms <NUM>, <NUM> between the main display supports <NUM>, <NUM> there is sufficient free space for enabling a partial curvature of the display segments 2b, 2c without conflicting with the respective main display supports.

In <FIG> another unclaimed 'wrap' type embodiment is shown comprising two slider elements, one slider element <NUM> in the bottom part 27a of the device body <NUM> and one slider element <NUM> on the display support <NUM> of the cover. In this embodiment the spring force biased mechanism comprises a sliding mounting of two sliding elements <NUM>, <NUM> both connected with a respective portion of the flexible display and both biased by the spring <NUM> in the direction of arrow d.

A spring <NUM> biases in the embodiment of <FIG> the slider element <NUM> and in the embodiment of <FIG> the two slider elements <NUM>, <NUM> with the attached part of the display <NUM> in the direction of arrow d. In these 'wrap' concepts in the closed position due to the spring <NUM> the display will be "stretched" around the main body. Thus the curved segments 2b, 2c are positioned at a distance from the hinge mechanisms providing design freedom for the construction of the hinge mechanisms. Preferably, when moving to the closed position the movement of the slider element <NUM> by the spring <NUM> in the direction d is limited by the abutment 27b on the bottom part 27a of the body <NUM>. Due to the spring force biased mechanism comprising the slider element in the open planar position sagging of the display at the location of the hinge mechanisms <NUM>, <NUM> is prevented. Due to this "stretching" in this position at the segments 2b, 2c the display <NUM> will feel stiff which gives a good quality perception of the display system and at these segments the display becomes more able to withstand touching with less deformation.

In <FIG> is shown a part of another unclaimed 'book' type embodiment with a hinge pin <NUM> in the connection between the housing halves <NUM> and <NUM>. In this embodiment the hinge pin <NUM> is part of a flexible hinge which has "flexible" hinge axis positions inside a hinge mechanism <NUM> and which is part of a spring force biased mechanism and enables a freedom of movement of the hinge pin in opposite directions e, f substantially parallel to the display surface in the open position.

In this embodiment the hinge pin is mounted in an elastic substance <NUM> (such as rubber). While moving from the closed position of <FIG> to the open position of <FIG> the display <NUM> becomes over-stretched and as shown in <FIG> the hinge pin will shift in the direction e and thereafter in opposite direction f between spring force biased positions to accommodate the required display length. This would also automatically provide a spring like function which would keep the display taut in the unsupported areas between the main display supports. In an alternative embodiment (not shown) instead of one hinge pin <NUM> a double hinge construction is applied of the type as shown in <FIG> in which both hinges are provided with a hinge pin mounted in an elastic substance <NUM>. In addition it is observed that instead of a rigid hinge pin rotatable in an elastic substance the pin may be made from an elastic material and the pin rotates in rigid substance.

It is observed that in an alternative solution (not shown) for the embodiments of <FIG> one of the portions of the flexible display <NUM> comprises an elastic border part, being connected with the respective main display support, biasing the flexible display in the open position. This elastic border part may be an alternative for the spring <NUM> or <NUM> in the respective embodiments, but may also be applied in these embodiments in combination with the spring <NUM> or <NUM> or in the embodiment of <FIG> in combination with the "flexible" hinge axis position.

The display system in accordance with the invention provides a way to assemble a flexible display in a housing, leaving one degree of freedom for movement of the display in the housing. Basically the invention allows one (or more) of the 'fixation' point(s) of the display to move relative to the hinge while closing the housing.

Essentially this reduces during closing the excess display length that needs to be compensated for.

An advantage of the invention is that the design freedom for the display system is much larger and not limited by the prior limited position of the hinge axis (or axes in case of double hinges).

A second advantage is that the display in open situation of the system can be pre-stretched by the spring (or spring means) <NUM> or <NUM>, located in the connection between the slider element and the housing, thus preventing the sagging of the display segment 2a, 2b, 2c respectively in the hinge area in the open situation. Because of this pre-stretching, the display will also be more able to withstand touching with less deformation.

In accordance with the invention the spring force biased mechanism - i.e. the slider or sliders <NUM> cooperating with the spring or springs <NUM> of <FIG>, the slider <NUM> or sliders <NUM>, <NUM> and the spring <NUM> of <FIG> and the flexible hinge <NUM> of <FIG> - is operative in either the open or closed position or both the open and closed positions of the flexible display, biasing the segment 2a, respective 2b, 2c of the flexible display in the respective position. Although in most cases the movement of the slider is limited by the end stop <NUM> during movement of the display from the open to the storage position the movement, alternatively this limitation occurs during movement of the display from the storage to the open position.

Finally due to the increased space available in the hinge area more space is available for a "touch support" mechanism such as described in <CIT>, later published as <CIT>. Such a "touch support" for the display segment 2a in combination with the pre-stretching of the display by the spring <NUM> may be advantageous for the life time of the display, especially in the gaps between the different display supports of the display system, where no support is available.

Claim 1:
A display system (<NUM>) comprising:
a continuous flexible display (<NUM>) comprising a first portion, a second portion and a central segment (2a), the central segment (2a) being unfixed and located between the first portion and the second portion;
a support frame comprising first (<NUM>) and second (<NUM>) display supports coupled by a hinge (<NUM>) having an axis, to be rotatable between a configuration for maintaining the flexible display in a closed position and a planar configuration for maintaining the flexible display in an open position, the first display support (<NUM>) fixed to the first portion of the flexible display (<NUM>) and the second display support (<NUM>) supporting the second portion of the flexible display (<NUM>);
a first slider element (<NUM>) being fixed with the second portion of the flexible display, and being slidably mounted on the second display support (<NUM>),
wherein a distance between a first fixation point of the first portion and the first display support (<NUM>), and a second fixation point of the second portion and the first slider element (<NUM>) in the closed position is smaller than a distance between the first fixation point and the second fixation point in the open position; and
the display system (<NUM>) further comprising a spring force biased mechanism comprising a spring (<NUM>) connected with the first slider element (<NUM>), and configured to bias the central segment (2a) of the flexible display away from the hinge (<NUM>) to maintain the display segment (2a) in a flat configuration when in the open position and configured to give more room for the hinge mechanism inside the display housing at the location of the hinge; and
wherein the location of the axis of the hinge (<NUM>) with respect to the display (<NUM>) in combination with the spring (<NUM>) is such that during movement to the open position the display (<NUM>) becomes over-stretched and thus ensures a stable open position of the display.