Patent Description:
Portable electronic devices, such as smart phones or tablets, have display screens. Typically, the display screen is fixed within a frame and occupies a fixed surface area.

Recently, electronic devices have been developed with display screens that are extendible and retractable (hereinafter, retractable screens). Electronic devices with foldable screens have also been developed.

One of the challenges facing the development of retractable screens is the implementation of a suitable extension and retraction mechanism. Conventional mechanisms for extension and retraction of retractable screens have a large number of moving components, such as motorized rollers. The mechanisms may also require extensions of the frame for supporting the extended display screen. Such extension mechanisms are power-inefficient, and make the electronic device complex, bulky, and expensive.

<CIT> discloses an electronic display device comprising a housing, a support panel and a guide in lieu of housing, the support panel and the guide, respectively. The guide guides and directs turning of the support panel and further moves or drives the support panel and the flexible display panel in at least one direction between at least one compact state and at least one extended state. The guide comprises a rotatable roller having sprocket teeth and a retractor extender. In one implementation, the retractor extender comprises a torsion spring having one portion coupled to the housing and a second portion coupled to the roller of the guide.

<CIT> discloses a slide mechanism including a base frame, a slide part sliding on the base frame, racks disposed on the base frame and facing each other, a pair of pinions which are disposed on the slide part freely rotatably and engaged with the racks, and a torsion spring with pins formed at both terminal parts.

It is an object of the present invention to provide a mechanism for extending and retracting a display screen that is power-efficient and compact.

According to a first implementation, a mechanism for retracting and extending a retractable portion of a display screen comprises a frame supporting the display screen and comprising an upper and a lower edge. A first rack is configured along the upper edge of the frame and is mechanically connected to the retractable portion. A second rack is configured along the lower edge of the frame and is mechanically connected to the retractable portion. At least one helical torsion spring extends between the upper and the lower edge of the frame. A first pinion is mechanically connected to the at least one torsion spring and is configured to drive the first rack linearly, and a second pinion is mechanically connected to the at least one torsion spring and is configured to drive the second rack linearly, such that rotation of the first and second pinions is transferred to in-plane movement of the retractable portion. When the retractable portion of the screen is retracted, the first and second pinions are rotated in a direction that increases a potential energy in the at least one helical torsion spring, and when the retractable portion of the screen is extended, the first and second pinions are rotated in a direction that decreases the potential energy in the at least one helical torsion spring.

Advantageously, the display screen is extended and retracted with a purely mechanical rack-and-pinion system, without requiring any motorized parts. In addition, the rack-and-pinion system and the torsion spring are integrated, so that retraction of the display screen automatically supplies the energy for subsequent extension of the display screen, without requiring supply of any additional energy.

In another implementation according to the first aspect, the mechanism includes at least one stopper locking rotation of the pinions when the retractable portion is retracted. Advantageously, the stopper maintains the screen in place without requiring constant application of manual force.

In another implementation according to the first aspect, upon release of the at least one stopper, the retractable portion is ejected automatically due to release of potential energy from the torsion spring. Advantageously, the automatic ejection mechanism is intuitive and easy to use. In addition, the force for the ejection comes from the potential energy stored in the torsion spring during the retraction of the screen, and thus does not require motorized force or substantial effort by a user.

The at least one torsion spring comprises at least two helical torsion springs joined by a grounding section, wherein, for each of the at least two helical torsion springs, a first end is attached to a pinion, and a second end is attached to the grounding section. Advantageously, a design with multiple torsion springs may permit a configuration that requires less space for the at least one torsion spring within the frame of the device, allowing for different configurations of electronic components within the frame.

In another implementation according to the first aspect, when the retractable portion is extended, the entire display screen is configured facing a first direction, and, when the retractable portion is retracted, the retractable portion of the display screen remains configured facing the first direction, and a non-retractable portion is configured facing a second direction. Advantageously, the arrangement of a portion of the screen facing the second direction when the retractable portion is retracted allows the screen to wrap around the frame, thereby allowing the screen to occupy less space.

In another implementation according to the first aspect, the display screen is part of a smart phone, tablet, or smart television device. Advantageously, the mechanism is usable to enhance screen size for these devices.

According to a second aspect, a method of retracting and extending a retractable portion of a display screen is disclosed. The display screen is supported by a frame comprising an upper and a lower edge. A first rack is configured along the upper edge of the frame and is mechanically connected to the retractable portion. A second rack is configured along the lower edge of the frame and is mechanically connected to the retractable portion. At least one helical torsion spring extends between the upper and lower edges of the frame. A first pinion is mechanically connected to the at least one torsion spring and is configured to drive the first rack linearly, and a second pinion is mechanically connected to the at least one torsion spring and is configured to drive the second rack linearly, such that rotation of the first and second pinions is transferred to in-plane movement of the retractable portion. The method comprises: retracting the retractable portion of the screen while rotating the first and second pinions in a direction that increases a potential energy in the at least one helical torsion spring, and extending the retractable portion of the screen while rotating the first and second pinions in a direction that decreases the potential energy in the at least one helical torsion spring.

Advantageously, the extending and retracting steps are performed with a purely mechanical rack-and-pinion system, without requiring any motorized parts. In addition, the rack-and-pinion system and the torsion spring are integrated, so that retraction of the display screen automatically supplies the energy for subsequent extension of the display screen, without requiring supply of any additional energy.

In another implementation according to the second aspect, the method further comprises, after the first moving step, engaging at least one stopper for locking rotation of the pinions. Advantageously, the stopper maintains the screen in place without requiring constant application of manual force.

In another implementation according to the second aspect, the method further comprises releasing the at least one stopper and thereby automatically ejecting the retractable portion due to release of potential energy from the torsion spring. Advantageously, the automatic ejection is intuitive and easy to use. In addition, the force for the ejection comes from the potential energy stored in the torsion spring during the retraction of the screen, and thus does not require motorized force or substantial effort by a user.

In another implementation according to the second aspect, when the retractable portion is extended, the entire display screen is configured facing a first direction, and, when the retractable portion is retracted, the retractable portion of the display screen remains configured facing the first direction, and a non-retractable portion is configured facing a second direction. Advantageously, the arrangement of a portion of the screen facing the second direction when the retractable portion is retracted allows the screen to wrap around the frame, thereby allowing the screen to occupy less space.

In another implementation according to the second aspect, the display screen is part of a smart phone, tablet, or smart television device. Advantageously, the mechanism is usable to enhance screen size for these devices.

According to a third aspect, a method of assembling a display screen with a retractable portion is disclosed. The method comprises: mounting the display screen onto a frame comprising an upper edge and a lower edge; configuring a first rack that is mechanically connected to the retractable portion along an upper edge of the frame, and configuring a second rack that is mechanically connected to the retractable portion along a lower edge of the frame; extending at least one helical torsion spring between upper and lower edges of the frame; and mechanically connecting first and second pinions to the at least one torsion spring, and configuring the first pinion to drive the first rack linearly, and the second pinion to drive the second rack linearly, such that rotation of the first and second pinions is transferred to in-plane movement of the retractable portion. When the retractable portion of the screen is retracted, the first and second pinions are rotated in a direction that increases a potential energy in the at least one helical torsion spring, and when the retractable portion of the screen is extended, the first and second pinions are rotated in a direction that decreases the potential energy in the at least one helical torsion spring.

Advantageously, a display screen assembled according to the disclosed method is extended and retracted with a purely mechanical rack-and-pinion system, without requiring any motorized parts. In addition, the rack-and-pinion system and the torsion spring are integrated, so that retraction of the display screen automatically supplies the energy for subsequent extension of the display screen, without requiring supply of any additional energy.

In another implementation according to the third aspect, the method further comprises further comprises installing at least one stopper for locking rotation of the pinions when the retractable portion is retracted. Advantageously, the stopper maintains the screen in place without requiring constant application of manual force.

The at least one torsion spring comprises at least two helical torsion springs joined by a grounding section, wherein, for each of the at least two helical torsion springs, the step of configuring at least one torsion spring comprises attaching a first end to a pinion, and a second end to the grounding section. Advantageously, a design with multiple torsion springs may permit a configuration that requires less space for the at least one torsion spring within the frame of the device, allowing for different configurations of electronic components within the frame.

The present invention, in some embodiments thereof, relates to a mechanism for retracting and extending a retractable portion of a display screen and, more specifically, but not exclusively, to a retractable electronic display screen that is extended and retracted by a rack-and-pinion system acting in concert with a torsion spring.

Reference is now made to <FIG>. Device <NUM> includes a retractable display screen <NUM>. Device <NUM> may be any device that has a display screen, such as a smart phone, tablet, or smart television device.

Display screen <NUM> is supported on a frame <NUM>. Frame <NUM> includes two parallel supports <NUM>. One support <NUM> is configured along an upper edge <NUM> of the frame <NUM>, and a second support <NUM> is configured along a lower edge <NUM> of the frame <NUM>. The terms upper edge <NUM> and lower edge <NUM> are used to describe opposing edges. Since the device <NUM> may be held in any direction, either of supports <NUM> may be an upper edge <NUM>, or a lower edge <NUM>. For purposes of illustration, upper edge <NUM> is depicted adjacent to cameras <NUM>, which would usually be upright when the device is held by a user, and lower edge <NUM> is depicted on the opposing edge. Helical torsion spring <NUM>, roller <NUM>, and stopper <NUM> are not visible in <FIG>, but their locations are indicated. The supports <NUM>, torsion spring <NUM>, roller <NUM>, and stopper <NUM> are part of a mechanism for retracting and extending the retractable portion <NUM>, in a manner that will be described further herein.

In <FIG>, the retractable display screen <NUM> is in an extended position. In the extended position, the entire screen <NUM> is visible from one side of the device <NUM>, referred to herein as the front of the device <NUM>. In <FIG>, the retractable display screen <NUM> is in a retracted position. In the retracted position, only portion <NUM> of the display screen is visible from the front of the device <NUM>, and portion <NUM> of the display screen is visible from the rear of the device <NUM>. Axis A depicts the dividing point between portion <NUM> and portion <NUM> of the display screen <NUM>. The term "retractable portion" refers to portion <NUM>, which is retracted or extended using the system described herein. Portion <NUM> is referred to herein as the non-retractable portion, because portion <NUM> moves only ancillary to movement of the retractable portion <NUM>. The direction of retraction is indicated by arrow B in <FIG>.

As seen in <FIG>, frame <NUM> also includes user interfaces <NUM>, <NUM>, for controlling features of device <NUM>. User interfaces <NUM>, <NUM> may be depressible buttons. User interface <NUM> may control a release of stopper <NUM> for extending the display screen <NUM>, as will be explained further herein. User interface <NUM> may be an on/off switch for the device <NUM>. The frame <NUM> may also include other components typically included in the electronic device <NUM>, such as one or more cameras <NUM>.

As seen best in <FIG>, racks <NUM> are mechanically connected to the retractable portion <NUM> of the screen. When the screen <NUM> is supported within the frame <NUM>, racks <NUM> are configured along the upper edge and lower edge of the frame <NUM>, respectively.

Referring now to <FIG>, the mechanism for retracting and extending retractable portion <NUM> is shown in detail. As seen in <FIG>, helical torsion spring <NUM> extends between the upper and lower edges of the frame <NUM>. The length of the torsion spring <NUM> is selected so that each end of the torsion spring <NUM> attaches to an upper or lower edge, respectively, of the frame <NUM>. Pinions <NUM> are mechanically connected to the torsion spring <NUM> and are configured to rotate along the racks <NUM>. The pinions <NUM> have gear teeth that cooperate with the racks <NUM> in a rack-and-pinion system, in a manner known to those of skill in the art. Rotation of the pinions <NUM> is thus transferred to in-plane movement of the retractable portion <NUM>.

To retract the screen <NUM>, a user pushes the retractable portion <NUM> in the direction of arrow B in <FIG>, for example, with a finger. The non-retractable portion <NUM> (not shown in <FIG>) curls in the direction of arrow R around roller <NUM> until it assumes the position of <FIG>. Simultaneously, the movement of rack <NUM> causes pinions <NUM> to rotate. This rotation of the pinions <NUM> causes an increase in potential energy of the torsion spring <NUM>.

The user continues to push the retractable portion <NUM> until the retractable portion <NUM> is completely retracted. At this point, stopper <NUM> (not shown in <FIG>) engages one or both pinions <NUM>, and/or the retractable screen <NUM>, to prevent further rotation of the pinions <NUM> and fix the screen <NUM> in the retracted position. Stopper <NUM> may take any form suitable for fixing the screen <NUM>. For example, stopper <NUM> may be a rod that is removably inserted between the teeth of pinions <NUM> when the screen <NUM> is completely retracted. Optionally, the stopper <NUM> may include a mechanical actuator which is automatically engaged by the screen <NUM> itself, when the screen <NUM> is fully retracted. Stopper <NUM> may also be manually actuated, such as with push button <NUM>. The location of the stopper <NUM> is highly dependent on the detailed architecture design of the device <NUM>, and can vary according to design needs for other architectural elements.

To extend the retractable portion, the user releases the stopper <NUM>, for example, by pushing push button <NUM>. The release of the stopper <NUM> allows the potential energy stored in the torsion spring <NUM> to be discharged through rotation of the torsion spring <NUM>. The rotation of torsion spring <NUM>, in turn, causes the pinions <NUM> to rotate. The rotation of the pinions <NUM> is translated to in-plane movement of the rack <NUM>, which causes retractable portion <NUM> to extend outward, until the position of <FIG> is attained again.

Advantageously, the mechanism for expanding and retracting the screen <NUM> disclosed herein utilizes a small number of moving parts. This allows the device <NUM> to be constructed in a compact and simple fashion. In addition, the use of the torsion spring <NUM> makes the mechanism entirely reliant on mechanical forces, without requiring use of motors. In addition, the rack-and-pinion system and the torsion spring are integrated, so that retraction of the display screen automatically supplies the energy for subsequent extension of the display screen, without requiring supply of any additional energy.

Referring now to <FIG>, helical torsion spring <NUM> may include two torsion springs 24a, 24b, joined by grounding section <NUM>. Each of the torsion springs 24a, 24b has, respectively, a first end 32a, 32b attached to a pinion, and a second end 34a, 34b, attached to the grounding section. The two helical torsion springs 24a, 24b may, in combination, function mechanically similarly to a single torsion spring <NUM>. An advantage of using two helical torsion springs 24a, 24b, is that the grounding <NUM> takes up less space than torsion spring <NUM>, and thus frees up space for inclusion of other components of device <NUM>. The number of torsion springs used in the device <NUM> may be determined by detailed antenna design and the clearance needed by other components of the device. Thus, more than two torsion springs <NUM> may also be used in device <NUM>.

The physical parameters of spring <NUM>, such as material, diameter, number of coils, and the like, may be engineered to meet requirements of roll and unroll speed and feeling. In one exemplary embodiment, the spring is made of music wire. Preferably, the music wire complies with the parameters of ASTM standard A228/A228M, for Steel Wire and Music Spring Quality. In one exemplary embodiment, the minimum tensile strength of the music wire spring material is around <NUM> x <NUM><NUM> psi, which corresponds to <NUM> MPa. The Design Stress may be less than <NUM>% of Minimum Tensile, which is 986MPa.

Similarly, the physical parameters of the pinions <NUM> and forces exerted thereby may be engineered according to desired size and feeling requirements. In one exemplary embodiment, the pinions rotate three times during a rolling or unrolling process. The length of each round is <NUM>. The gear pitch radius may be <NUM>. The intermittent torque may be <NUM> mNm (milli-Newton meters), and the intermittent force, calculated as intermittent torque divided by gear pitch radius, may be <NUM> N. The continuous torque may be <NUM> mNm, so that the continuous force, calculated as continuous torque divided by gear pitch radius, is <NUM> N.

<FIG> illustrates certain physical parameters of torsion spring <NUM>, as the spring <NUM> is subjected to increased bending stress when the screen <NUM> is moved from the extended position to the retracted position. Arrow F in <FIG> represents an increase in force as the spring is moved along deflection angle ϕ. The change in deflection angle ϕ is shown as a dot-dash line. The output force F exerted on the spring is calculated based on the following equation: <MAT> where d is the diameter of the spring (as illustrated in <FIG>), r is the spring length (as illustrated in <FIG>), and σ is the bending stress. The deflection angle ϕ is determined by the following equation: <MAT> where D is the mean coil diameter (as illustrated in <FIG>), E is the Young's modulus, d is the diameter of the spring wire, and σ is the bending stress.

As can be seen from these equations, for a given spring in which the spring diameter, mean coil diameter, Young's modulus, and spring length r are fixed, the angle ϕ and the force F are both linearly dependent on the bending stress σ. In one exemplary spring, the diameter d is <NUM> x <NUM>-<NUM> m, the mean coil diameter D is <NUM> x <NUM>-<NUM> m, the spring length r is <NUM> x <NUM>-<NUM> m, and the Young's modulus is <NUM> x <NUM><NUM> Pa. In addition, in an exemplary embodiment, the number of active coils n may be <NUM>, and the total spring length is <NUM> x <NUM>-<NUM> m (spring diameter d x number of active coils n). Following the above-referenced formulas, when the preload bending stress σ (also known as preload deflection) is <NUM> x <NUM><NUM> Pa, the output force F is <NUM> N, and the spring deflection ϕ is <NUM> degrees. When the bending stress σ is increased to <NUM> x <NUM><NUM> Pa, the output force is increased to <NUM> N, and the spring deflection ϕ is increased to <NUM> degrees.

The descriptions of the various embodiments of the present invention have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.

It is expected that during the life of a patent maturing from this application many relevant devices having display screens will be developed and the scope of the terms device and display screen is intended to include all such new technologies a priori.

Claim 1:
A mechanism for retracting and extending a retractable portion (<NUM>) of a display screen (<NUM>), comprising:
a frame (<NUM>) supporting the display screen (<NUM>) and comprising an upper (<NUM>) and a lower edge (<NUM>);
a first rack (<NUM>) configured along the upper edge (<NUM>) of the frame (<NUM>) and mechanically connected to the retractable portion (<NUM>), and a second rack (<NUM>) configured along the lower edge (<NUM>) of the frame (<NUM>) and mechanically connected to the retractable portion (<NUM>);
at least one helical torsion spring (<NUM>) extending between the upper (<NUM>) and the lower edge (<NUM>) of the frame (<NUM>);
a first pinion (<NUM>) mechanically connected to the at least one torsion spring (<NUM>) and configured to drive the first rack (<NUM>) linearly, and a second pinion (<NUM>) mechanically connected to the at least one torsion spring (<NUM>) and configured to drive the second rack (<NUM>) linearly, such that rotation of the first and second pinions (<NUM>) is transferred to in-plane movement of the retractable portion (<NUM>);
wherein, when the retractable portion (<NUM>) of the screen (<NUM>) is retracted, the first and second pinions (<NUM>) are rotated in a direction that increases a potential energy in the at least one helical torsion spring (<NUM>), and when the retractable portion (<NUM>) of the screen (<NUM>) is extended, the first and second pinions (<NUM>) are rotated in a direction that decreases the potential energy in the at least one helical torsion spring (<NUM>); and
characterised in that
the at least one torsion spring (<NUM>) comprises at least two helical torsion springs (24a, 24b) joined by a grounding section (<NUM>), wherein, for each of the at least two helical torsion springs (24a, 24b), a first end (32a, 32b) is attached to a pinion (<NUM>), and a second end (34a, 34b) is attached to the grounding section (<NUM>).