Patent Description:
Flexible displays, such as rotatable displays can be used to provide adaptive form factors for electronic devices. For example, a mobile phone with a flexible display could be configured in a first configuration which is more compact and easier to transport and a second configuration which provides a large display area.

<CIT> discloses a display device that includes a rollable display panel that has two surfaces opposed to each other, and a heat dissipation sheet disposed on one of the two surfaces of the display panel that is rollable together with the rollable display panel. The heat dissipation sheet has a thermal conductivity greater than <NUM> W/mK. <CIT> discloses oscillating heat pipes for use in bendable electronic devices. <CIT> discloses a self-excited oscillation heat pipe having flexibility, and a computer provided therewith.

According to examples of the invention there is provided an apparatus comprising:.

The oscillating heat pipe may be positioned behind the flexible display in the flexible portion.

The one or more condenser regions in the flexible portion may be configured to enable surfaces of the flexible portion to be used as heat rejection surfaces.

The flexible portion may be a rollable portion.

The housing may comprise a rotatable member and one end of the rollable portion may be coupled to the rotatable member such that rotation of the rotatable member enables the rollable portion to be moved between the open configuration and the closed configuration.

The rotatable member may be thermally coupled to a non-rotatable member and one or more heat sources are thermally coupled to the non-rotatable member.

The flexible display may comprise organic light emitting diodes.

The oscillating heat pipe may be configured to transfer heat to one or more organic light emitting diodes in the flexible display.

Pressure within the oscillating heat pipe may be above atmospheric pressure so that the oscillating heat pipe provides structural rigidity to the flexible portion when the flexible portion is in the open configuration.

The oscillating heat pipe may comprise a polymer.

The flexible portion may comprise a diffusion barrier.

The oscillating heat pipe may comprise a first section having a first diameter and a second section having a second diameter such that the different diameters enable different heat transfer rates by the respective sections.

The apparatus may comprise one or more vapor chambers wherein the vapor chambers are configured to transfer heat between the one or more heat sources and the oscillating heat pipe.

The apparatus may comprise means for detecting whether the flexible portion is in an open configuration or a closed configuration and causing a first thermal management strategy for the one or more heat sources to be implemented if the flexible portion is in the open configuration and causing a second thermal management strategy to be implemented for the one or more heat sources if the flexible portion is in the closed configuration.

According to various, but not necessarily all, examples of the disclosure there may be provided an electronic device comprising an apparatus as described herein wherein the electronic device comprises one or more of: a mobile phone, a teleconferencing device, a television.

While the above examples of the invention and optional features are described separately, it is to be understood that their provision in all possible combinations and permutations is contained within the disclosure. It is to be understood that various examples of the disclosure can comprise any or all of the features described in respect of other examples of the disclosure, and vice versa.

Certain features and views of the figures can be shown schematically or exaggerated in scale in the interest of clarity and conciseness. For example, the dimensions of some elements in the figures can be exaggerated relative to other elements to aid explication. Corresponding reference numerals are used in the figures to designate corresponding features. For clarity, all reference numerals are not necessarily displayed in all figures.

Examples of the invention relate to an apparatus with a flexible display. The flexible display can be moved between an open configuration and a closed configuration. In the closed configuration the flexible display is housed within a housing. In the open configuration the flexible display is not housed in the housing. In the open configuration the flexible display can provide a large surface area. In examples of the disclosure an oscillating heat pipe is thermally coupled to the flexible display to enable the large surface area of the flexible display to be used for improving cooling of electronic components that might be comprised within the housing.

<FIG> schematically show an example apparatus <NUM> according to examples of the disclosure. The example apparatus <NUM> comprises a housing portion <NUM> and a flexible portion <NUM>. The apparatus <NUM> could comprise additional features that are not shown in <FIG>.

<FIG> show the apparatus <NUM> in an open configuration. <FIG> shows the apparatus <NUM> in a closed configuration. <FIG> show a side view of the apparatus <NUM> and <FIG> shows a front view of the apparatus <NUM>.

The housing <NUM> can comprise a rigid casing that is configured to enclose or at least partially enclose one or more heat sources <NUM> or other components of the apparatus <NUM>. The housing <NUM> can be configured to protect the one or more heat sources <NUM> or other components. For example, it can protect the heat sources <NUM> or other components from impacts and/or from dirt, fluids and other contaminants.

The housing <NUM> can be formed from a rigid plastic or any other suitable material. The housing <NUM> is rigid in that it cannot be easily deformed by a user of the apparatus <NUM> during normal use of the apparatus <NUM>.

In the example of <FIG> the housing <NUM> has a cuboid, or substantially cuboid, shape. The housing <NUM> has rectangular cross sections. Other shapes for the housing <NUM> could be used in other examples of the invention.

One or more heat sources <NUM> are contained within the housing <NUM>. The heat sources <NUM> could be a component that generates unwanted heat during use of the apparatus <NUM>. For example, the heat sources <NUM> could be an electronic or photonic component such as a battery or processing unit.

In the example of <FIG> the heat sources <NUM> are shown as discrete components. In some examples the heat sources <NUM> can be integrated for instance the components <NUM> heat sources <NUM> could comprise integrated circuits or any other suitable type of components or combinations of components.

Two heat sources <NUM> are shown in <FIG>. Any number of heat sources could be contained within the housing <NUM> in other examples.

The flexible portion <NUM> configured to be moved between a closed configuration and an open configuration. In the closed configuration the flexible portion <NUM> is housed in the housing <NUM>. <FIG> shows the flexible portion <NUM> in the closed configuration. In this example the flexible portion <NUM> is entirely contained within the housing <NUM>. In other examples, the flexible portion <NUM> could be housed within the housing <NUM> so that a small section of the flexible portion <NUM> is not within the housing <NUM>. For example, a small section of the flexible portion <NUM> could be positioned on or outside of the surface of the housing <NUM>. This could enable a user of the apparatus <NUM> to pull the flexible portion <NUM> into the open configuration.

In the open configuration the flexible portion <NUM> is positioned outside of the housing <NUM>. <FIG> show the flexible portion <NUM> in the open configuration. In this example the flexible portion <NUM> is entirely positioned outside of the housing <NUM>. In other examples, the flexible portion <NUM> could be positioned outside of the housing <NUM> so that a small section of the flexible portion <NUM> is retained within the housing <NUM>. For example, a small section of the flexible portion <NUM> could be coupled to a mechanism within the housing <NUM>. The mechanism could enable the flexible portion <NUM> to be moved between the open configuration and the closed configuration.

The flexible portion <NUM> is flexible in that it can be rolled or bent. The flexibility of the flexible potion <NUM> enables the flexible portion <NUM> to be folded or bent into a compact configuration that can be housed within the housing <NUM>. This can provide for a compact form factor that is convenient for transporting the apparatus <NUM> and/or for storing the apparatus <NUM>. The flexibility of the flexible portion <NUM> also enables the flexible portion <NUM> to be arranged into a flat or substantially flat configuration. The flat configuration provides a large surface are of the flexible portion. This large surface area can be used to display images or to enable any other suitable functions to be performed.

The flexible portion <NUM> comprises a flexible display <NUM> and an oscillating heat pipe <NUM>. The flexible portion <NUM> could comprise other components in other examples of the disclosure.

The flexible display <NUM> can comprise any means for displaying images that can be rolled or bent between the open and closed configurations. In some examples the flexible display <NUM> can comprise an array of light emitting diodes. The array of light emitting diodes can be configured so that moving the flexible display <NUM> between the open and closed configurations does not damage the light emitting diodes. The light emitting diodes could comprise organic light emitting diodes (OLEDs) or any other suitable type of diodes.

The flexible display <NUM> can be controlled by a controller or other suitable means that could be housed within the housing <NUM>. The flexible display <NUM> can be electronically coupled to the controller or any other suitable means to enable images to be displayed on the flexible display <NUM> when the flexible display <NUM> is in the open configuration.

The oscillating heat pipe <NUM> is flexible and is configured to move with the flexible portion <NUM> between the closed configuration and the open configuration. The oscillating heat pipe <NUM> can be formed from a flexible material such a polymer or any other suitable material.

The oscillating heat pipe <NUM> can comprise means for transferring heat from the one or more heat sources <NUM> in the housing <NUM> to the surface of the foldable portion <NUM>. One or more intervening components can be provided between the heat source <NUM> and the oscillating heat pipe <NUM>. One or more intervening components can be provided between the oscillating heat pipe <NUM> and the surface of the foldable portion <NUM>.

The oscillating heat pipe <NUM> comprises one or more evaporator regions and one or more condenser regions. The evaporator regions and condenser regions are shown in more detail in <FIG>.

The one or more evaporator regions of the oscillating heat pipe <NUM> can be positioned in the flexible portion so that they are close to the housing <NUM> or are located in the housing <NUM>. The one or more evaporator regions are thermally coupled to one or more heat sources <NUM> to allow for heat transfer into the oscillating heat pipe <NUM>. In some examples the evaporator region could be thermally coupled to a single heat source <NUM>. In other examples the evaporator region could be thermally coupled to a plurality of different heat sources <NUM>. The one or more evaporator regions could be directly connected to the one or more heat sources <NUM> so that there are no intervening components between the heat sources <NUM> and the one or more evaporator regions. In other example intervening components could be used to transfer heat from the heat sources <NUM> to the one or more evaporator regions. For instance, one or more vapor chambers can be configured to transfer heat between the heat sources <NUM> and the one or more evaporator regions of the oscillating heat pipe <NUM>.

One or more of the condenser regions are located in the flexible portion <NUM>. The one or more condenser regions can be located in the flexible portion <NUM> so that they are not close to the housing <NUM> when the flexible portion105 is in an open configuration. For instance, the one or more of the condenser regions could be located towards a distal end of the flexible portion <NUM>. The distal end could be the end of the flexible portion <NUM> that is opposite to the end that is attached to the housing <NUM>.

The one or more of the condenser regions are coupled to a heat sink to allow for heat transfer out of the oscillating heat pipe <NUM>. The heat sink could be a heat spreader, a vapour chamber or any other suitable means for removing heat from the oscillating heat pipe <NUM>.

In the examples of <FIG> the oscillating heat pipe <NUM> is positioned behind the flexible display <NUM> in the flexible portion <NUM>. This means that the oscillating heat pipe <NUM> does not obstruct the images displayed by the flexible display <NUM>. Other positions for the oscillating heat pipe <NUM> could be used in other examples of the disclosure.

The oscillating heat pipe <NUM> can be configured to have any suitable size or shape within the foldable portion <NUM>. In the example of <FIG> the oscillating heat pipe <NUM> is distributed over all of, or substantially all of, the area of the foldable portion <NUM>. This can enable all of, or substantially all of the surface area of the flexible portion <NUM> to be used to transfer heat away from the heat sources <NUM>.

In the example of <FIG> the flexible portion <NUM> is thin. The flexible portion <NUM> is thin in that the depth of the flexible portion <NUM> much smaller than the height and width of the flexible portion <NUM>. The flexible portion <NUM> could be several millimeters thick or even thinner whereas the height and width of the flexible portion <NUM> could be several cm or even over a meter in the case of televisions.

Having a thin flexible portion <NUM> can make it easier to move the flexible portion <NUM> between the open and closed configurations. This can also make it easier to fit the flexible portion <NUM> inside the housing <NUM> in the closed configuration because the thin flexible portion <NUM> will not require much volume for storage.

Having a thin flexible portion <NUM> can also improve the efficiency of the heat transfer by the oscillating heat pipe <NUM> because it can enable either surface of the flexible portion <NUM> to be used or rejecting heat.

The apparatus <NUM> is therefore configured so that, when the apparatus <NUM> is in an open configuration heat from the heat sources <NUM> in the housing can be transferred into the oscillating heat pipe <NUM>. The oscillating heat pipe <NUM> can then transfer the heat to the one or more condenser regions in the flexible portion <NUM>. The relatively large surface area of the flexible portion <NUM> can then be used to enable heat to be transferred out of the oscillating heat pipe <NUM>. For instance, the surface area of the flexible portion <NUM> can allow for cooling by convection from the respective surfaces. As the flexible portion <NUM> can be thin this can enable both of the surfaces of the flexible portion <NUM> to be used for cooling by convection which can improve the efficiency of the heat transfer. The apparatus <NUM> therefore provides for cooling of heat sources <NUM> within electronic devices comprising flexible portions.

The oscillating heat pipe <NUM> provides a passive cooling system for the apparatus <NUM>. The cooling system is passive in that it does not require a pump or other driver to move working fluid within the oscillating heat pipe <NUM>. The oscillating heat pipe <NUM> can be designed so that the apparatus <NUM> can function in different orientations. The efficiency of the apparatus <NUM> can be improved if the oscillating heat pipe <NUM> is configured so that the movement of working fluid in the oscillating heat pipe <NUM> is aided by gravity.

The apparatus <NUM> according to examples of the invention can be provided in any suitable types of devices. In some examples the apparatus <NUM> could be provided in portable devices such as mobile phones or other types of communication devices. In such cases the closed configuration can provide a compact configuration that makes the portable device easy to transport. For instance, having the flexible portion <NUM> in a closed configuration can enable the portable device to be transported in a user's pocket or bag for example. The open configuration can provide a large surface area for a display or user interface or other suitable means.

In some examples the apparatus <NUM> could be provided in electronic devices that are not portable. For instance, the apparatus <NUM> could be provided in a wall mounted display that could be part of a television of conferencing system. In these examples, having the flexible portion <NUM> in a closed configuration can enable the device to be stored compactly so that it Is not taking up a large area of a wall or room. The open configuration can provide a large surface area for a display or user interface or other suitable means.

Various modifications and/or additions could be made to the apparatus <NUM> in implementations of the invention.

For instance, in the examples of <FIG> the flexible portion <NUM> is shown as a rollable portion. Other types of flexible portion <NUM> could be used in other examples. For instance, the flexible portion <NUM> could be a foldable portion that could be folded into the housing <NUM> in a concertina arrangement.

In some examples the heat transferred by the oscillating heat pipe <NUM> could be used to heat one or more components in the flexible portion <NUM>. For instance, if the flexible display <NUM> comprises organic light emitting diodes (OLEDs) these can operate more efficiently at a temperature that is higher than ambient temperature. In such cases the condenser region of the oscillating heat pipe <NUM> can be designed so that the heat transferred out of the oscillating heat pipe <NUM> is used to heat the OLEDs. This can improve the efficiency of the flexible display <NUM>. Therefore, in these cases the oscillating heat pipe <NUM> is configured to transfer heat from a region where it is unwanted or disadvantageous, to a region where the heat is beneficial.

In some examples the flexible portion <NUM> can comprise a diffusion barrier. The diffusion barrier can be configured to protect both the oscillating heat pipe <NUM> and the components of the display <NUM> such as the OLEDs. In other examples different diffusion barriers could be used to protect the respective components. For example, a first diffusion barrier could be used to protect the oscillating heat pipe <NUM> and a second diffusion barrier could be used to protect the OLEDs or other components of the flexible portion <NUM>.

The diffusion barrier can be configured to help to prevent working fluid from leaking out of the oscillating heat pipe <NUM> and/or to help to prevent ingress of non-condensable gases into the oscillating heat pipe <NUM>. The diffusion barrier can be formed from any suitable material.

In some examples the pressure within the oscillating heat pipe <NUM> can be above atmospheric pressure. The pressurization of the working fluid within the oscillating heat pipe <NUM> can help to provide a structural rigidity to the oscillating heat pipe <NUM>. This structural rigidity can help to support the flexible portion <NUM> and provide some structural rigidity to the flexible portion <NUM> when the flexible portion <NUM> is in the open configuration.

In some examples the oscillating heat pipe <NUM> can be designed so that the support provided by the pressurized oscillating heat pipe <NUM> can provide a particular shape for the flexible portion <NUM>. For instance, the oscillating heat pipe <NUM> can be designed so that in the open configuration the flexible portion <NUM> is concave or convex or in any other suitable configuration.

The oscillating heat pipe <NUM> can be moved between the open and closed configurations, even when the working fluid is pressurized, due to the compressibility of the vapor within the oscillating heat pipe <NUM>.

The working fluid used in the oscillating heat pipe <NUM> can be selected so as to reduce or minimize the diameter for the oscillating heat pipe <NUM>. In such examples the working fluid that is used within the oscillating heat pipe <NUM> can be selected to have a small confinement number. In some examples the working fluid is selected to have a confinement number less than one. The suggested confinement number can be between <NUM> and <NUM>.

The confinement number is given by: <MAT> where <MAT> is the capillary length, γ is the working fluid surface tension, g is the acceleration due to gravity, Δp is the density difference between the liquid and vapour phase of the working fluid and ri is the inner radius of the oscillating heat pipe <NUM>.

Having a small confinement number, for example a confinement number below one, reduces the impact of surface tension related instabilities on the functioning of the oscillating heat pipe <NUM>.

The working fluid that is used within the oscillating heat pipe <NUM> can comprise fluorine. For example, the working fluid could be R236fa, R1233zd, R245fa or any other suitable working fluid. Such working fluids have characteristically small γ and large Δρ and so provide low confinement numbers. Such working fluids are dielectric and may have low global warming potential (GWP) values.

The oscillating heat pipe <NUM> can be configured to reduce or minimize the effects of ingress of non-condensable gases from the atmosphere into the oscillating heat pipe <NUM>. The non-condensable gases, such as oxygen and nitrogen could diffuse into the oscillating heat pipe <NUM>. Such gases would degrade the performance of the oscillating heat pipe <NUM>. In some examples the oscillating heat pipe <NUM> could comprise a diffusion barrier, as described above, which could restrict the ingress of the non-condensable gases.

In some examples the working fluid that is used within the oscillating heat pipe <NUM> is configured to have a vapour pressure that is high enough to reduce effects of ingress of non-condensable gases into the oscillating heat pipe <NUM>. The working fluid can be selected to have a high vapour pressure (low boiling point) so that if the concentration of non-condensable gases within the oscillating heat pipe <NUM> is equilibrated with the external pressure the mass fraction of the non-condensable gases remains low relative to the working fluid. This ensures that the thermal performance of the oscillating heat pipe <NUM> remains high. Working fluids such as R236fa, R1233zd, R245fa have suitably high vapour pressures at operating temperatures of the oscillating heat pipe <NUM>.

In some examples the oscillating heat pipe <NUM> can be formed from polymer. The polymer that is used can be selected so as to reduce interaction between the oscillating heat pipe <NUM> and the working fluid. The polymer can be selected to have a good chemical compatibility and low mass uptake with respect to the working fluid. The polymer that is used can be weakly permeable to a high molecular weight working fluid. For instance, if R1233zd is used as the working fluid then suitable polymers for the oscillating heat pipe <NUM> could comprise Epichlorohydrin rubber (ECO), Neoprene, silicone, or Butyl.

The oscillating heat pipe <NUM> could be weakly permeable to the working fluid and so in some examples the oscillating heat pipe <NUM> can be configured to reduce or minimize this fluid loss. For instance, in some examples the surface area of oscillating heat pipe <NUM> can be minimized. In some examples the oscillating heat pipe <NUM> can be overfilled to begin with so as to allow for a predictable, but acceptable, change in the thermal performance of the oscillating heat pipe <NUM> during the lifetime of apparatus <NUM>. For instance, the initial charging ratio could be between <NUM> to <NUM>% and could drop, over the lifetime of the apparatus <NUM>, to around <NUM>% which would still provide an acceptable thermal performance.

The polymer that is used for the oscillating heat pipe <NUM> can be selected to have sufficient tensile strength to avoid bursting of the oscillating heat pipe <NUM> as the flexible portion <NUM> is moved between the open configuration and the closed configuration. The burst pressure for the oscillating heat pipe <NUM> is given by: <MAT> where σT is the tensile strength of the polymer used for the bendable region <NUM>, ro is the outer radius of the oscillating heat pipe <NUM> and ri is the inner radius of the oscillating heat pipe <NUM>.

Due to the small dimensions of the oscillating heat pipe <NUM> that would be used in examples of the disclosure the burst pressures can be very large. As an example, Neoprene has σT ~ <NUM> bar (Shore A <NUM> hardness), typical dimensions for the oscillating heat pipe <NUM> could be ro/ri = <NUM>/<NUM> and a safety factor of <NUM>, this gives Δpburst/<NUM> = <NUM> bar. This compares favorably with R236fa saturation pressure of <NUM> bar at <NUM>.

The oscillating heat pipe <NUM> can also be designed to reduce ingress of non-condensable gases into the oscillating heat pipe <NUM>. For example, the oscillating heat pipe <NUM> can be designed to reduce the diffusion of non-condensable gases across the polymer of the oscillating heat pipe <NUM>. It can be difficult to prevent ingress of such gases due to the small molecular size of diatomic oxygen and nitrogen. In some examples a diffusion barrier, as mentioned above, can be used. In some examples selection of working fluid could be used instead of, or in addition to the diffusion barrier. For example, a working fluid with a low boiling point (high vapor pressure) can be used so that even if the concentration of non-condensable gases in the oscillating heat pipe <NUM> reaches equilibrium with the external pressure, the mass fraction of non-condensable gases remains low relative to the working fluid so that thermal performance of the oscillating heat pipe <NUM> remains high. Working fluids such as R236fa, R1233zd, R245fa demonstrate high vapor pressures at the oscillating heat pipe <NUM> operating temperature and could be suitable choices. Other fluids could be used in other examples.

In some examples the oscillating heat pipe <NUM> can be designed so that it has different diameters at different sections. For instance, the oscillating heat pipe <NUM> could comprise a first section having a first diameter and a second section having a second diameter. The different diameters can enable different heat transfer rates by the respective sections. This can enable different levels of cooling to be provided for different parts of the apparatus <NUM>. For instance, a first heat source <NUM> could generate more unwanted heat than a second heat source <NUM>. In these cases, the section of the oscillating heat pipe <NUM> that transfers heat away from the first heat source <NUM> could have a larger diameter than the section of the oscillating heat pipe <NUM> that transfers heat away from the second heat source <NUM>. This can enable a higher rate of cooling to be provided to the heat sources <NUM> that requires the most cooling.

In some examples the apparatus <NUM> can comprise a detector or other suitable means for detecting whether the flexible portion <NUM> is in the open configuration or the closed configuration. For instance, a sensor could be located in the housing <NUM> and used to detect the position of the flexible portion <NUM>. The detector can cause a thermal management strategy for the heat sources <NUM> to be implemented based on the detected position of the flexible portion <NUM>. For instance, a first thermal management strategy can be implemented if the flexible portion <NUM> is detected to be in the open configuration and a second thermal management strategy can be implemented if the flexible portion <NUM> is detected to be in the closed configuration. The first thermal management strategy could allow the temperatures of the one or more heat sources <NUM> to exceed a threshold temperature because efficient heat transfer is available through the oscillating heat pipe <NUM> and the surface of the flexible portion <NUM>. The second thermal management strategy could throttle the operation of the one or more heat sources <NUM> and prevent them from exceeding the threshold temperature because efficient heat transfer is not available through the oscillating heat pipe <NUM> and the surface of the flexible portion <NUM> when the flexible portion <NUM> is inside the housing <NUM>.

<FIG> show part of an example apparatus <NUM>. In this example the flexible portion <NUM> is shown in a closed configuration. The housing <NUM> is not shown in <FIG>. The flexible portion <NUM> is shown in a side view in <FIG> and a perspective view in <FIG>. The flexible portion <NUM> can comprise a flexible display <NUM> and an oscillating heat pipe <NUM>. The flexible display <NUM> and the oscillating heat pipe <NUM> can be as described above or in any other suitable arrangement. The flexible display <NUM> and theoscillating heat pipe <NUM> are not shown in <FIG>.

<FIG> show a mechanism <NUM> for moving the flexible portion <NUM> between the open configuration and the closed configuration. In this example the flexible portion <NUM> is a rollable portion comprising a rollable display and the mechanism <NUM> comprises a roller mechanism. Other types of mechanism <NUM> could be used for other types of flexible portions <NUM> such as foldable portions.

The mechanism <NUM> comprises a rotatable member <NUM> and a non-rotatable member <NUM>. The mechanism <NUM> could comprise additional components that are not shown in <FIG>.

The rotatable member <NUM> is configured to rotate. The rotatable member <NUM> is mechanically coupled to an end of the flexible portion <NUM> so that rotation of the rotatable member <NUM> causes movement of the flexible portion <NUM>. The flexible portion <NUM> can be coupled to the rotatable member <NUM> so that rotation of the rotatable member <NUM> in a first direction causes the flexible portion <NUM> to be moved toward the closed configuration. In the example of <FIG> this direction would be a clockwise direction. In the closed configuration the flexible portion <NUM> is wrapped around the rotatable member <NUM>.

The flexible portion <NUM> can be coupled to the rotatable member <NUM> so that rotation of the rotatable member <NUM> in a second direction causes the flexible portion <NUM> to be moved toward the open configuration. In the example of <FIG> this direction would be an anti-clockwise direction. In the open configuration the flexible portion <NUM> is not wrapped around the rotatable member <NUM>.

The rotatable member <NUM> is coupled to the non-rotatable member <NUM>. The rotatable member <NUM> can be thermally and mechanically coupled to the non-rotatable member <NUM>.

The non-rotatable member <NUM> is configured so that it does not rotate when the rotatable member <NUM> rotates. The non-rotatable member <NUM> can be fixed in position within the housing <NUM> so that the non-rotatable member <NUM> does not move relative to the housing <NUM> and other components within the housing.

In some examples the non-rotatable member <NUM> can be configured to secure the rotatable member <NUM> in position within the housing <NUM> while allowing rotation of the rotatable member <NUM>. For example, the non-rotatable member <NUM> can be configured to enable rotation of the rotatable member <NUM> but can be configured to restrict translational movement of the rotatable member <NUM>.

In the example of <FIG> the non-rotatable member <NUM> comprises a planar portion <NUM>. The planar portion <NUM> comprises a flat or substantially flat surface. In the example mechanism <NUM> a gap is provided between the rotatable member <NUM> and the planar portion <NUM> so that when the flexible portion <NUM> is rolled up in the closed configuration part of the rolled up flexible portion is positioned in the gap.

In some examples one or more heat sources <NUM> can be mounted on, or embedded in the planar portion <NUM>. This can enable the one or more heat sources <NUM> to be thermally coupled to the non-rotatable member <NUM>. In other examples the heat sources <NUM> might not be mounted on, or embedded in, the planar portion <NUM> but could be otherwise be thermally coupled to the non-rotatable member <NUM>. For example, one or more vapor chambers could be used to thermally connect a heat source <NUM> to the non-rotatable member <NUM>.

The rotatable member <NUM> can be thermally coupled to the non-rotatable member <NUM> so that heat from the non-rotatable member <NUM> can be transferred to the rotatable member <NUM>. This heat can be heat from one or more heat sources <NUM>.

The oscillating heat pipe <NUM> of the flexible portion <NUM> can be thermally coupled to the rotatable member <NUM>. This can enable heat from the rotatable member <NUM> to be transferred to the oscillating heat pipe <NUM>. For example, one or more evaporator regions of the oscillating heat pipe <NUM> can be positioned close to the rotatable member <NUM> so that heat from the rotatable member <NUM> heats working fluid in the evaporator regions of oscillating heat pipe <NUM>.

If the flexible portion <NUM> is in an open configuration oscillating heat pipe <NUM> can then transfer the heat away from the housing <NUM> and to the large surface area of the open flexible portion <NUM>. The mechanism <NUM> therefore enables rotation of the flexible portion <NUM> and also efficient heat transfer from the heat sources <NUM> to the oscillating heat pipe <NUM>.

<FIG> schematically shows an example oscillating heat pipe <NUM> that could be used in examples of the invention. The oscillating heat pipe <NUM> comprises a condenser region <NUM>, an evaporator region <NUM> and an adiabatic section <NUM>.

The evaporator region <NUM> comprises any means for transferring heat from a heat source <NUM> into the working fluid within the oscillating heat pipe <NUM>. The evaporator region <NUM> is thermally coupled to a heat source107. In this example the heat sources <NUM> can be any one or more of the heat sources <NUM> in the housing <NUM> of the apparatus <NUM>.

The condenser region <NUM> comprises any means for transferring heat out of the working fluid within the oscillating heat pipe <NUM>. The condenser region <NUM> is thermally coupled to a heat sink or any other suitable type of means for transferring heat out of the working fluid. The heat sink could be a heat rejection surface or any other suitable means. The heat sink can be within the flexible portion <NUM> of the apparatus <NUM>.

The oscillating heat pipe <NUM> is configured in a meandering or serpentine configuration comprising a plurality of bends. A first plurality of bends is located in the evaporator region <NUM> and a second plurality of bends is located in the condenser region <NUM>.

In the example shown in <FIG> three U-shaped bends are shown in the evaporator region <NUM> and two U-shaped bends are shown in the condenser region <NUM>. Other configurations and numbers of bends could be used in other examples of the disclosure. For instance, in other examples the bends might not be U-shaped. The meandering or serpentine configuration is configured so that the working fluid within the oscillating heat pipe <NUM> is alternately heated in the evaporator region <NUM> and cooled in the condenser region <NUM> of the oscillating heat pipe <NUM>.

In the example shown in <FIG> the oscillating heat pipe <NUM> forms a closed loop. Other types of oscillating heat pipe <NUM> could be used in other examples of the invention.

In the example shown in <FIG> an adiabatic section <NUM> is provided between the evaporator region <NUM> and the condenser region <NUM>. The adiabatic section <NUM> extends between the bends in the condenser region <NUM> and the bends in the evaporator region <NUM>. The adiabatic section <NUM> ensures that heat that is transferred into the working fluid in the evaporator region <NUM> is retained within the oscillating heat pipe <NUM> until the working fluid reaches the condenser region <NUM>. In some examples the oscillating heat pipe <NUM> does not comprise an adiabatic section <NUM>. Whether or not the oscillating heat pipe <NUM> comprises an adiabatic section <NUM> can depend on the application and system geometry of the oscillating heat pipe <NUM> and any other suitable factors.

When the oscillating heat pipe <NUM> is in use, heat is applied to the working fluid in the bends within the evaporator region <NUM>. This heat causes, at least some of, the working fluid to evaporate. This evaporation results in an increase of vapour pressure inside the oscillating heat pipe <NUM> which causes the growth of bubbles <NUM> within the evaporator region <NUM>. The growth of the bubbles <NUM> and the increase in vapour pressure forces liquid slugs <NUM> of the working fluid towards the condenser region <NUM>. The working fluid that is pushed to the condenser region <NUM> is then cooled by the condenser. This cooling reduces the vapour pressure within the working fluid and causes condensation of the bubbles <NUM> and provides a restoring force that pushes the working fluid back towards the evaporator region <NUM>. This process of alternate bubble growth and condensation causes oscillation of the working fluid within the oscillating heat pipe <NUM> and allows for an efficient heat transfer between the evaporator region <NUM> and the condenser region <NUM>.

The example oscillating heat pipe <NUM> in <FIG> comprises a single loop with a single evaporator region <NUM>. In some examples the oscillating heat pipe <NUM> could comprise a plurality of loops. The different loops could comprise different evaporator regions <NUM>. The different evaporator regions could be configured to dissipate heat from different heat sources <NUM> within the housing of the apparatus <NUM>. Having the plurality of loops can provide for design flexibility within the oscillating heat pipe111. This can enable the number of bends and the geometry of the oscillating heat pipe <NUM> to be optimized, or substantially optimized, for dissipating heat from the different heat sources <NUM> within the housing of the apparatus <NUM>.

In this description and claims the term coupled means operationally coupled. Any number or combination of intervening elements can exist between coupled components, including no intervening elements.

The apparatus can be provided in an electronic device, for example, a mobile terminal, according to an example of the present invention. It should be understood, however, that a mobile terminal is merely illustrative of an electronic device that would benefit from examples of implementations of the present invention and, therefore, should not be taken to limit the scope of the present invention to the same. While in certain implementation examples, the apparatus can be provided in a mobile terminal, other types of electronic devices, such as, but not limited to: mobile communication devices, hand portable electronic devices, wearable computing devices, portable digital assistants (PDAs), pagers, mobile computers, desktop computers, televisions, gaming devices, laptop computers, cameras, video recorders, GPS devices and other types of electronic systems, can readily employ examples of the present invention.

Furthermore, devices can readily employ examples of the present invention regardless of their intent to provide mobility.

In this description, the wording 'connect', 'couple' and 'communication' and their derivatives mean operationally connected/coupled/in communication. It should be appreciated that any number or combination of intervening components can exist (including no intervening components), i.e., so as to provide direct or indirect connection/coupling/communication. Any such intervening components can include hardware and/or software components.

As used herein, the term "determine/determining" (and grammatical variants thereof) can include, not least: calculating, computing, processing, deriving, measuring, investigating, identifying, looking up (for example, looking up in a table, a database or another data structure), ascertaining and the like. Also, "determining" can include receiving (for example, receiving information), accessing (for example, accessing data in a memory), obtaining and the like. Also, " determine/determining" can include resolving, selecting, choosing, establishing, and the like.

The term 'a', 'an' or 'the' is used in this document with an inclusive not an exclusive meaning. That is any reference to X comprising a/an/the Y indicates that X may comprise only one Y or may comprise more than one Y unless the context clearly indicates the contrary. If it is intended to use 'a', 'an' or 'the' with an exclusive meaning then it will be made clear in the context. In some circumstances the use of 'at least one' or 'one or more' may be used to emphasis an inclusive meaning but the absence of these terms should not be taken to infer any exclusive meaning.

Claim 1:
An apparatus (<NUM>) comprising:
a housing portion (<NUM>) comprising one or more heat sources (<NUM>);
a flexible portion (<NUM>) configured to be moved between a closed configuration and an open configuration wherein in the closed configuration the flexible portion (<NUM>) is housed in the housing portion (<NUM>) and in the open configuration the flexible portion (<NUM>) is positioned outside of the housing (<NUM>);
wherein the flexible portion (<NUM>) comprises a flexible display (<NUM>) ; characterised in that the flexible portion further comprises an oscillating heat pipe (<NUM>) and the oscillating heat pipe (<NUM>) is coupled to the one or more heat sources (<NUM>) in the housing portion (<NUM>) and the oscillating heat pipe (<NUM>) is flexible and configured to move with the flexible portion (<NUM>) between the closed configuration and the open configuration and wherein one or more condenser regions of the oscillating heat pipe (<NUM>) are positioned in the flexible portion (<NUM>).