Patent ID: 12259758

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments may be implemented in various forms, and should not be construed as being limited to the embodiments set forth herein; on the contrary, these embodiments are provided so that the present disclosure will be comprehensive and complete, and the concept of the example embodiments is fully conveyed to those skilled in the art. The same reference numerals in the figures indicate the same or similar structures, and thus their detailed descriptions will be omitted.

When a foldable flexible display device is folded inward and outward, various film layers thereof are subjected to different forces. For example, the film layer that is subjected to a pressure when being folded inward may be subjected to a tension when being folded outward. In the case where the foldable flexible display device can be folded both inward and outward, the strain of each film layer is relatively large, especially when the foldable display device is folded inward. Generally, each film layer will have a maximum strain when the foldable display device is folded inward, so that an adhesive material fails, and a functional layer of the flexible display panel also fails due to the large strain, which causes the foldable flexible display device to fail to display normally.

Moreover, in the related art, a water-drop shape formed when the foldable flexible display device is folded inward is not smooth, and a corner will be formed, which will also cause the strain of each film layer to be large and cause the adhesive to fail, and the functional layer of the flexible display panel35will also fail due to the large strain, so that the foldable flexible display device cannot display normally.

An exemplary embodiment provides a display device. Referring toFIGS.1to3, which show schematic structural diagrams of a display device according to an exemplary embodiment of the present disclosure, the display device may include: a first support member1, having a first surface11and a second surface12that are arranged oppositely; a second support member2, having a gap8with the first support member1, and having a third surface21and a fourth surface22that are arranged oppositely; and a flexible display module3, arranged on the first surface11of the first support member1and the third surface21of the second support member2. The first surface11includes a first mating surface111close to the second support member2, the third surface21includes a third mating surface211close to the first support member1, and the first mating surface111and the third mating surface211are arranged symmetrically to each other. A distance from at least part of the first mating surface111to the flexible display module3increases as a distance from the at least part of the first mating surface111to the second support member2decreases, and a distance from at least part of the third mating surface211to the flexible display module3increases as a distance from the at least part of the third mating surface211to the first support member1decreases, so that when the display device is folded inward, the flexible display module3contacts with the at least part of the first mating surface111and the at least part of the third mating surface211to form a water-drop shape.

In the display device of the exemplary embodiment, the distance from at least part of the first mating surface111to the flexible display module3increases as the distance from the at least part of the first mating surface111to the second support member2decreases, and the first mating surface111and the third mating surface211are arranged symmetrically to each other, that is, the distance from at least part of the third mating surface211to the flexible display module3increases as the distance from the at least part of the third mating surface211to the first support member1decreases, so that when the display device is folded inward, the flexible display module3contacts with at least part of the first mating surface111and at least part of the third mating surface211to form the water-drop shape. Due to the support of the first mating surface111and the third mating surface211, the water-drop shape formed by the flexible display module3is relatively smooth and does not have a corner, which avoids a large stress of each film layer, thereby avoiding the failure of the adhesive material and the functional layer, and being suitable for the display device that can be folded both inward and outward.

In an exemplary embodiment, the “away from” and “close to” is referred in a state when the display device is in a flat state. A length direction is a direction perpendicular to a bending direction of the display device, and a width direction is a direction perpendicular to the length direction and parallel to the flexible display module3.

In an exemplary embodiment, the first support member1has the first surface11and the second surface12, and the first surface11and the second surface12are arranged opposite to each other. The second surface12may be a plane, and the flexible display module3may be arranged on the first surface11. The second support member2has the third surface21and the fourth surface22, and the third surface21and the fourth surface22are arranged opposite to each other. The fourth surface22may be a plane, and the flexible display module3may be arranged on the third surface21.

The first support member1and the second support member2may have the same structure, the gap8is provided between the first support member1and the second support member2, and the first support member1and the second support member2are symmetrically arranged, that is, the first surface11and the third surface21are symmetrical to each other.

Specifically, an area of the first surface11close to the second support member2is the first mating surface111, and the first mating surface111may include a bonding plane a, an inclined surface b, and a limiting plane d. The bonding plane a is located at an end of the first mating surface111far away from the bending position, and the limiting plane d is located at an end of the first support member1close to the bending position. The limiting plane d is arranged parallel to the bonding plane a, and both the limiting plane d and the bonding plane a are parallel to the flexible display module3. The flexible display module3is bonded on the bonding plane a through a bonding layer5. In a flat state, there is a space between the limiting planed and the flexible display module3.

An area of the third surface21close to the first support member1is the third mating surface211, and the third mating surface211may also include a bonding plane a, an inclined surface b, and a limiting plane d. The bonding plane a is located at an end of the third mating surface211far away from the bending position, and the limiting plane d is located at an end of the second support member2close to the bending position. The limiting plane d is arranged parallel to the bonding plane a, and both the limiting plane d and the bonding plane a are parallel to the flexible display module3. The flexible display module3is bonded on the bonding plane a through the bonding layer5. In the flat state, there is a space between the limiting plane d and the flexible display module3.

The inclined surface b is connected between the bonding plane a and the limiting plane d. There is a smooth transition between the inclined surface b and the bonding plane a. The inclined surface b is inclined from the bonding plane a to the limiting plane d to a side away from the flexible display module3, and an inclination angle α of the inclined surface b is about 15 degrees, that is, the angle α between the inclined surface b and the second surface12is approximately 15 degrees, and the angle α between the inclined surface b and the fourth surface22is approximately 15 degrees. Of course, the inclination angle α of the inclined surface b may be greater than or equal to 10 degrees and less than or equal to 20 degrees.

The inclined surface b transitions to the limiting plane d through an arc surface c protruding to the flexible display module3, and the inclined surface b and a tangent plane of the arc surface c are coplanar with each other, that is, the arc surface c is connected between the inclined surface b and the limiting plane d, the arc surface c protrudes toward the flexible display module3, the arc surface c is tangent to the inclined surface b, so that there is a smooth transition between the arc surface c and the inclined surface b. That is, the first support member1forms a partial cylinder at the arc surface c, and the tangent plane of the cylinder is a plane that passes through a generatrix of the cylinder and is perpendicular to the axis cross section passing the generatrix. In addition, in other exemplary embodiments of the present disclosure, the arc surface c connected between the inclined surface b and the limiting plane d may also be an elliptical arc surface c, a parabolic arc surface c and the like, as long as it can contact with the flexible display module3when the display device is folded inward to cause the flexible display module3to form a smooth water-drop shape.

In an exemplary embodiment, referring toFIG.2, a width L1of the limiting plane d is about 6 mm±1 mm. It should be noted that the width L1of the limiting plane d is about 6 mm±1 mm, which means that the width L1of the limiting plane d is greater than or equal to 5 mm (6 mm-1 mm) and less than or equal to 7 mm (6 mm+1 mm). Each data mentioned later represents an interval value, not a point value and corresponds to a numerical range in the claims. A sum L2of the width of the inclined plane b and the width of the limiting plane d is approximately 14 mm±1 mm. After the display device is folded inward, a minimum distance H1between the first support member1and the second support member2is about 2 mm, and an inward folded shape of a smooth water-drop shape with a radius R1of about 3 mm is formed. Referring toFIG.3, after the display device is folded outward, a maximum distance H2between the first support member1and the second support member2is about 10 mm, an outward folded shape of a smooth “U” shape with a radius R2of about 5 mm is formed. Of course, the width of the limiting plane d and the width of the inclined surface b may also be set as required.

In an exemplary embodiment, the bonding plane a extends to the side away from the bending position to support the flexible display module3. Since the structures of the first support member1and the second support member2may be exactly the same, the extension length of the bonding plane a of the first support structure1is the same as the extension length of the bonding plane a of the second support member2.

Of course, in other exemplary embodiments of the present disclosure, the first mating surface111and the third mating surface211may be formed into a shape that completely matches the smooth water-drop shape that needs to be formed, so that when the display device is folded inward, the flexible display module3is fully attached to the first mating surface111and the third mating surface211to support the flexible display module3. The structures of the first support member1and the second support member2may also be different. For example, the width of the first support member1and the width of the second support member2may not be the same, that is, the extension length of the bonding plane a of the first support member1is different from the extension length of the bonding plane a of the second support member2, so that the bending position of the display device is not in the middle position. As long as the first mating surface111and the third mating surface211are symmetrically arranged, a smooth and symmetrical water-drop shape can be formed, thereby avoiding a display failure caused by uneven stresses of the flexible display module3and various functional layers when being folded inward.

Referring toFIGS.4and5, a first frame61is further arranged at the periphery of the first support member1, and the first frame61surrounds the other three edges of the first support member1than the edge where the first mating surface111is arranged. Two ends of the first frame61protrude with respect to the first mating surface111, the two ends of the first frame61protruding with respect to the first mating surface111are provided with two first fixing shafts in one-to-one correspondence, and a first gear13is provided on the first fixing shaft.

A second frame62is further arranged at the periphery of the second support member2, and the second frame62surrounds the other three edges of the second support member2than the edge where the third mating surface211is arranged. Two ends of the second frame62protrude with respect to the third mating surface211, the two ends of the second frame62protruding with respect to the third mating surface211are provided with two second fixing shafts in one-to-one correspondence, and a second gear23is provided on the second fixing shaft.

Referring toFIGS.4and5, the display device further includes two connecting parts7having the same structure. The connecting part7includes at least one matching gear71. The matching gear71is arranged between the first gear13and the second gear23, and externally engages with the first gear13and the second gear23, so that both the first support member1and the second support member2may rotate relative to the connecting part7to realize the inward or outward folding of the display device.

The specific structure of the flexible display module3will be described in detail below.

Referring toFIG.6, which shows a schematic structural diagram of the flexible display module3according to an exemplary embodiment of, the flexible display module3may include a flexible support plate31, a protective layer32, a backsheet layer33, a first adhesive layer34, and a flexible display panel35, a second adhesive layer36, a polarizer37, a third adhesive layer38, a first cover plate39, a fourth adhesive layer40and a second cover plate41.

The flexible support plate31is adhered to a part of the first surface11and a part of the third surface21. The protective layer32is arranged on a side of the flexible support plate31away from the first support member1and the second support member2; the backsheet layer33is arranged on a side of the protective layer32away from the flexible support plate31; the first adhesive layer34is arranged on a side of the backsheet layer33away from the flexible support plate31; the flexible display panel35is arranged on a side of the first adhesive layer34away from the flexible support plate31; the second adhesive layer36is arranged on a side of the flexible display panel35away from the flexible support plate31; the polarizer37is arranged on a side of the second adhesive layer36away from the flexible support plate31; the third adhesive layer38is arranged on a side of the polarizer37away from the flexible support plate31; the first cover plate39is arranged on a side of the third adhesive layer38away from the flexible support plate31; the fourth adhesive layer40is arranged on a side of the first cover plate39away from the flexible support plate31; the second cover plate41is arranged on a side of the fourth adhesive layer40away from the flexible support plate31.

The positional relationship of each film layer of the flexible display module3is described above, and the thickness and performance requirements of each film layer are described below.

The flexible support plate31may be a metal support plate, a thickness of the flexible support plate31may be 150 μm±10 μm, and an equivalent elastic modulus thereof may be 10 Kpa±2 Kpa. The flexible support plate31provides support for the entire flexible display module3.

A material of the protective layer32may be foam. The protective layer32may protect the backsheet layer33. The protective layer32may prevent the flexible support plate31from damaging the backsheet layer33. Adhesive layers are arranged on both sides of the protective layer32for bonding to the flexible support plate31and the backsheet layer33.

A material of the backsheet layer33may be polyimide, a thickness of the backsheet layer33may be 23 μm±3 μm, and an elastic modulus of the backsheet layer33may be 3.2 GPa±0.5 Gpa. The backsheet layer33may support and protect the flexible display panel35.

A material of the first adhesive layer34may be OCA optical adhesive (Optically Clear Adhesive), and a thickness of the first adhesive layer34may be 15 μm±3 When the temperature is 25° C., an elastic modulus of the first adhesive layer34is 45 KPa±10 Kpa; when the temperature is −20° C., the elastic modulus of the first adhesive layer34is 130 KPa±10 Kpa; when the temperature is 60° C., the elastic modulus of the first adhesive layer34is 40 KPa±5 KPa. The first adhesive layer34is used for bonding the flexible display panel35and the backsheet layer33.

The OCA optical adhesive is a special adhesive for bonding transparent optical components (such as lenses). The OCA optical adhesive is required to have the characteristics such as being colorless and transparent, light transmittance above 90%, good bonding strength, being cured at a room temperature or medium temperature, and a small curing shrinkage. The OCA optical adhesive is a special double-sided adhesive tape of an optically transparent layer with no substrate.

The flexible display panel35may be an OLED (organic light emitting diode) display panel, a QLED (quantum dot light emitting diode) display panel or the like. The flexible display panel35may be any type of display panel that can be made flexible, and the specific structure of the display panel will not be repeated here.

A material of the second adhesive layer36may also be the OCA optical adhesive. A thickness of the second adhesive layer36may be 15 μm±5 μm. When the temperature is 25° C., an elastic modulus of the second adhesive layer36is 80 KPa+10 KPa; when the temperature is −20 At ° C., the elastic modulus of the second adhesive layer36is 130 KPa±10 Kpa; when the temperature is 65° C., the elastic modulus of the second adhesive layer36is 70 KPa+10 KPa. The second adhesive layer36is used for bonding the flexible display panel35and the polarizer37.

A thickness of the polarizer37may be 45 μm±5 and an elastic modulus of the polarizer37is 3.2 GPa+0.5 GPa. A basic structure of the polarizer37includes a middle PVA (polyvinyl alcohol) layer, two layers of TAC (triacetyl cellulose), a PSA (pressure sensitive adhesive) film, a release film and a protective film. The PVA layer plays the role of polarization. The PVA is easily hydrolyzed, and in order to protect the physical property of such polarizing film, TAC films with high light transmittance, good water resistance and certain mechanical strength are combined on both sides of the PVA respectively for protection, which forms the original plate of the polarizer37.

A material of the third adhesive layer38may also be the OCA optical adhesive. A thickness of the third adhesive layer38may be 50 μm±5 μm. When the temperature is 25° C., an elastic modulus of the third adhesive layer38is 55 KPa±10 KPa; when the temperature is −20° C., the elastic modulus of the third adhesive layer38is 120 KPa±10 Kpa; when the temperature is 60° C., the elastic modulus of the third adhesive layer38is 35 KPa±5 KPa. A curing rate of the third adhesive layer38is 68%±3%. The third adhesive layer38is used for bonding the polarizer37and the first cover39.

Thicknesses of the first cover plate39and the second cover plate41may both be 85 μm±5 Materials of the first cover plate39and the second cover plate41may be polyimide or polyimide and PET (polyethylene terephthalate). The fourth adhesive layer40is used for bonding the first cover plate39and the second cover plate41. Two layers of cover plates (the first cover plate39and the second cover plate41) may increase the scratch resistance and impact resistance of the display device, and prevent scratches and impacts from damaging each functional layer when the display device is folded outward.

In a second exemplary embodiment of the present disclosure, the thickness of the third adhesive layer38may be adjusted while keeping other conditions unchanged. Specifically, the material of the third adhesive layer38may also be the OCA optical adhesive. The thickness of the second adhesive layer36may be 100 μm±10 μm. When the temperature is 25° C., the elastic modulus of the third adhesive layer38is 55 KPa±10 KPa; when the temperature is −20° C., the elastic modulus of the third adhesive layer38is 120 KPa±10 Kpa; when the temperature is 60° C., the elastic modulus of the third adhesive layer38is 35 KPa+5 KPa. The curing rate of the third adhesive layer38is 68%±3%.

In a third exemplary embodiment of the present disclosure, the elastic modulus of the third adhesive layer38may be adjusted while keeping other conditions unchanged. Specifically, the material of the third adhesive layer38may also be the OCA optical adhesive, the thickness of the second adhesive layer36may be 50 μm±5 The elastic modulus of the third adhesive layer38is 140 KPa+10 KPa when the temperature is 25° C. The curing rate of the third adhesive layer38is 68%±3%.

In a fourth exemplary embodiment of the present disclosure, the thickness of the polarizer37may be adjusted while keeping other conditions unchanged. Specifically, the thickness of the polarizer37may be 90 μm±10 and the elastic modulus of the polarizer37is 3.2 GPa±0.5 GPa.

In a fifth exemplary embodiment of the present disclosure, the elastic modulus of the backsheet layer33may be adjusted while keeping other conditions unchanged. Specifically, the material of the backsheet layer33may be polyimide, the thickness of backsheet layer33may be 23 μm±3 μm, and the elastic modulus of the backsheet layer33is 9 GPa±1 Gpa.

The various film layers in the above exemplary embodiment are matched with each other, and are obtained through countless experiments.

FIG.7shows a finite element simulation schematic diagram of a strain of the second adhesive layer36and the third adhesive layer38in which the ordinate is a strain amount, andFIG.8shows a finite element simulation schematic diagram of a strain of the flexible display panel35in which the ordinate is a strain amount. The strain amount in the figure is the maximum strain in the process that the display device changes from the inward folding state to the outward folding state. The comparison of the following data is a comparison of each exemplary embodiment with the first exemplary embodiment.

It can be seen from the drawings that in the first exemplary embodiment, the strain of the second adhesive layer36is approximately 124%, the strain of the third adhesive layer38is approximately 136%, the strain of the flexible display panel35is approximately 0.225%, and the strains of the flexible display panel35, the second adhesive layer36and the third adhesive layer38are all relatively small. In the second exemplary embodiment, the strain of the second adhesive layer36is slightly reduced to about 122%, however, the strain of the third adhesive layer38is increased greatly to about 180%, and the strain of the flexible display panel35is increased slightly to about 0.23%. In the third exemplary embodiment, the strain of the second adhesive layer36is increased greatly to about 162%, the strain of the third adhesive layer38is increased greatly to about 160%, and the strain of the flexible display panel35is increased greatly to about 0.42%. In the fourth exemplary embodiment, the strain of the second adhesive layer36is slightly increased to approximately 148%, the strain of the third adhesive layer38is slightly increased to approximately 142%, and the strain of the flexible display panel35is slightly reduced to about 0.21%. In the fifth exemplary embodiment, the strain of the second adhesive layer36remains basically unchanged, the strain of the third adhesive layer38is slightly reduced to about 134%, the strain of the flexible display panel35is increased greatly to about 0.46%.

Therefore, it can be seen from the above comparison that the first exemplary embodiment is the best, the second and fourth exemplary embodiments are the second-best, and the third and fifth exemplary embodiments are the third-best. However, the strain of each film layer in the above five exemplary embodiments is smaller than the strain of the corresponding film layer in the prior art. In the experiment, the strains of the second adhesive layer36and the third adhesive layer38in the prior art are greater than 200%, and the strain of the flexible display panel is greater than 0.5%.

Referring toFIG.9, in another exemplary embodiment of the present disclosure, the fourth adhesive layer40and the second cover plate41may not be provided.

The features, structures, or characteristics described above may be combined in one or more embodiments in any suitable manner. If possible, the features discussed in the embodiments are interchangeable. In the above description, many specific details are provided to provide a sufficient understanding of the embodiments of the present disclosure. However, those skilled in the art will realize that the technical solutions of the present disclosure may be practiced without one or more of the specific details, or by using other methods, components, material. In other cases, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the present disclosure.

The terms “about” and “approximately” used in the specification usually means within 20% of a given value or range, preferably within 10%, and more preferably within 5%. The quantity given herein is an approximate quantity, which means “about”, “approximately”, “substantially” and “round” in the absence of specific instructions.

Although relative terms such as “upper” and “lower” are used in this specification to describe the relative relationship between one component and another component shown, these terms are used in this specification only for convenience of description, for example, according to the direction shown in the drawings. It can be understood that if the device shown is turned upside down, the components described as “upper” will become the “lower” components. Other relative terms, such as “high”, “low”, “top”, and “bottom” have similar meanings. When a structure is “on” another structure, it may mean that a certain structure is integrally formed on another structure, or that a certain structure is “directly” disposed on another structure, or that a certain structure is “indirectly” disposed on another structure through an other structure.

In this specification, the terms “a”, “an”, “the”, “said” and “at least one” are used to indicate that there are one or more elements/components/etc.; the terms “including”, “comprising” and “having” are used to mean open-ended inclusion and means that in addition to the listed elements/components/etc., there may be additional elements/components/etc.; the terms “first” and “second” and “third” are only used as markers, and are not a limitation on the number of objects.

It should be understood that the present disclosure is not limited to the detailed structure and arrangement of the components provided in this specification. The present disclosure have other embodiments, and may be implemented and executed in various ways. The aforementioned changes and modifications fall within the scope of the present disclosure. It should be understood that the present disclosure disclosed and defined in this specification extends to all alternative combinations of two or more individual features mentioned or obvious in the text and/or drawings. All these different combinations constitute a plurality of alternative aspects of the present disclosure. The embodiments described in this specification illustrate the best implementation for the present disclosure, and will enable those skilled in the art to utilize the present disclosure.