Display panels and display modules

Abstract

The present disclosure relates to a display panel comprising a flexible substrate having a first side and a second side opposite each other. An OLED device is provided on the first side, and a heat dissipation film layer is directly bonded to the second side, or a heat conductive film layer and a heat dissipation film layer are sequentially provided on the second side in a direction away from the flexible substrate. The heat conductive film layer includes at least one stacked sub-heat conductive film layer. The present disclosure also relates to a display module.

Description

Technical Field

[0001] The present disclosure relates to the technical field of display product manufacturing, and in particular to a display panel and a display module. Background Art

[0002] Organic light-emitting diodes (OLEDs) are known as "dream displays" due to their self-luminescence, high efficiency, vibrant colors, thinness, power efficiency, rollability, and wide operating temperature range. In recent years, OLEDs have been widely used in small and medium-sized displays and are gradually entering the fields of large-area displays, automotive applications, and lighting.

[0003] Flexible, foldable panels allow for more flexible design, significantly enhancing the technological appeal of automotive display panels and representing a future trend in automotive display technology. However, OLED display panels also generate Joule heating during use, raising the temperature of the display panel (for example, at an ambient temperature of 26.3°C, or room temperature, a full-white display with no heat dissipation structure reaches a temperature of 37.6-43.1°C at 600 nits, with an in-plane temperature difference of 5.5°C). This temperature increase accelerates the brightness decay of the OLED display panel (for example, the lifetime decay rate of an OLED display panel at 85°C is much faster than at room temperature. For example, after 500 hours, the brightness decays to 97.97% of the initial brightness at room temperature, but to 72% at 85°C). Given the longevity of a car, which often lasts 10 years or more, the long-term heat resistance requirements for the panel are very high. Improving the heat dissipation of OLED panels is a technical challenge that those skilled in the art need to address. Summary of the Invention

[0004] In order to solve the above technical problems, the present disclosure provides a display panel and a display module to improve the heat dissipation problem of the display panel.

[0005] In order to achieve the above-mentioned objectives, the technical solution adopted in the embodiments of the present disclosure is: a display panel, including a flexible substrate, the flexible substrate including a first side and a second side opposite to each other, the first side being provided with an OLED device, the second side being directly adhered with a heat dissipation functional film layer, or a thermal conductive film layer and a heat dissipation functional film layer being sequentially provided on the second side in a direction away from the flexible substrate, the thermal conductive film layer including at least one sub-thermal conductive film layer being stacked.

[0006] Optionally, the heat dissipation functional film layer includes a high thermal conductivity adhesive, and the high thermal conductivity adhesive is made of one or more of acrylic resin, silicon-based material, thermal grease, and liquid metal.

[0007] Optionally, the heat dissipation functional film layer further includes a metal layer located on a side of the high thermal conductive adhesive away from the flexible substrate.

[0008] Optionally, the heat dissipation functional film layer includes one or more film layers made of Al, Cu, graphite sheets, and nano-copper carbon.

[0009] Optionally, the heat-conducting film layer includes one or two film layers selected from the group consisting of a back film layer, a grid adhesive layer, and a buffer layer.

[0010] Optionally, the thermally conductive film layer includes the stacked back film layer and / or the grid adhesive layer, and a buffer layer is provided on a side of the heat dissipation functional film layer away from the flexible substrate.

[0011] Optionally, a heat insulation layer is provided on a side of the heat dissipation functional film layer away from the flexible substrate.

[0012] Optionally, the heat dissipation functional film layer includes a temperature vapor chamber.

[0013] Optionally, a plurality of heat dissipation columns are provided on a side of the temperature homogenizing plate away from the flexible substrate.

[0014] Optionally, the display panel includes a flexible circuit board electrically connected through a chip-on-film, the flexible circuit board is bent to a side of the temperature vapor chamber away from the flexible substrate, the orthographic projection of the flexible circuit board on the temperature vapor chamber is located in a first area, and the heat dissipation column is located in a second area of ​​the temperature vapor chamber adjacent to the first area.

[0015] Optionally, the height of the heat dissipation column in a direction perpendicular to the flexible substrate increases sequentially along a direction from the second area to the first area.

[0016] Optionally, a cross-sectional area of ​​the heat dissipation column in a direction parallel to the flexible substrate gradually decreases in a direction away from the flexible substrate.

[0017] Optionally, the distribution density of the heat dissipation columns increases sequentially along the direction from the second area to the first area.

[0018] Optionally, the flexible substrate is a curved surface structure that is bent in at least a first direction, and along the first direction, the distribution density of the heat dissipation columns gradually increases from both ends of the temperature vapor chamber to the middle.

[0019] Optionally, the area of ​​the direct projection of the heat dissipation column located in the middle area of ​​the temperature homogenizing plate on the temperature homogenizing plate is a first area, and the area of ​​the direct projection of the heat dissipation column located in the edge area of ​​the temperature homogenizing plate on the temperature homogenizing plate is a second area, and the first area is greater than the second area.

[0020] Optionally, the flexible circuit board is connected to the temperature equalizing plate via a connector.

[0021] Optionally, the heat dissipation column is reused as the connecting piece.

[0022] The present disclosure also provides a display module, comprising a cover plate and the display panel, and an optical film layer located between the cover plate and the display panel.

[0023] The temperature t1 at the first position on the light-emitting side of the OLED device satisfies the following formula:

[0024]

[0025] The temperature t2 of the second position located on the backlight side of the OLED device satisfies the following formula:

[0026]

[0027] R1 or R2 is obtained by the following formula:

[0028] q0 is obtained by the following formula: q0 = p / s

[0029] Wherein, q0 is the total heat flux density, p is the heat generation power of the display panel, s is the heat dissipation area of ​​the display panel, R1 is the thermal resistance of the light-emitting side of the OLED device, R2 is the thermal resistance of the backlight side of the OLED device, x is the distance between the first position or the second position and the OLED device, λ is the thermal conductivity of each film layer between the first position or the second position and the OLED device, h is the air convection heat transfer coefficient, t ∞ is the ambient temperature.

[0030] The beneficial effect of the present disclosure is to remove the film layer with poor thermal conductivity between the flexible substrate and the heat dissipation functional film layer, or even directly attach the heat dissipation functional film layer to the backlight side of the flexible substrate, thereby effectively achieving heat dissipation of the display panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram showing the structure of a display panel in related art Figure 1 ;

[0032] Figure 2 Schematic diagram showing the structure of the display panel in the embodiment of the present disclosure Figure 1 ;

[0033] Figure 3 Schematic diagram showing the structure of the display panel in the embodiment of the present disclosure Figure 2 ;

[0034] Figure 4 Schematic diagram showing the structure of the display panel in the embodiment of the present disclosure Figure 3 ;

[0035] Figure 5 Schematic diagram showing the structure of the display panel in the embodiment of the present disclosure Figure 4 ;

[0036] Figure 6 Schematic diagram showing the structure of the display panel in the embodiment of the present disclosure Figure 5 ;

[0037] Figure 7 Schematic diagram showing the structure of the display panel in the embodiment of the present disclosure Figure 6 ;

[0038] Figure 8 Schematic diagram showing heat dissipation simulation results;

[0039] Figure 9 Schematic diagram showing the comparison between measured values ​​and calculated values;

[0040] Figure 10 Schematic diagram showing the structure of the display panel in the embodiment of the present disclosure Figure 7 ;

[0041] Figure 11 Schematic diagram showing the structure of the display panel in the embodiment of the present disclosure Figure 8 ;

[0042] Figure 12 Schematic diagram showing the temperature distribution of the display panel Figure 1 ;

[0043] Figure 13 Schematic diagram showing the temperature distribution of the display panel Figure 2 ;

[0044] Figure 14 Schematic diagram showing the structure of the display panel in the embodiment of the present disclosure Figure 9 ;

[0045] Figure 15 Schematic diagram showing the structure of the display panel in the embodiment of the present disclosure Figure 10 ;

[0046] Figure 16 Schematic diagram showing the structure of the display panel in the embodiment of the present disclosure Figure 10 one;

[0047] Figure 17 Schematic diagram showing the structure of a display panel in related art Figure 2 ;

[0048] Figure 18 express Figure 17 Side view of;

[0049] Figure 19 Schematic diagram showing the structure of the display panel in the embodiment of the present disclosure Figure 10 two;

[0050] Figure 20 express Figure 19 Side view of;

[0051] Figure 21 Schematic diagram of the structure of a flexible circuit board Figure 1 ;

[0052] Figure 22 Schematic diagram of the structure of a flexible circuit board Figure 2 ;

[0053] Figure 23 Schematic diagram showing the structure of the display panel in the embodiment of the present disclosure Figure 10 three;

[0054] Figure 24 Schematic diagram showing the structure of the display panel in the embodiment of the present disclosure Figure 10 Four;

[0055] Figure 25 Schematic diagram showing the structure of the display panel in the embodiment of the present disclosure Figure 10 five;

[0056] Figure 26 Schematic diagram showing the structure of the display panel in the embodiment of the present disclosure Figure 10 six;

[0057] Figure 27 express Figure 26 Side view of;

[0058] Figure 28 Schematic diagram showing the structure of the display panel in the embodiment of the present disclosure Figure 10 seven;

[0059] Figure 29 express Figure 28 Side view of;

[0060] Figure 30 Schematic diagram showing the structure of the display panel in the embodiment of the present disclosure Figure 10 eight. DETAILED DESCRIPTION

[0061] To make the purpose, technical solutions, and advantages of the embodiments of the present disclosure more clear, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the described embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of this disclosure.

[0062] In the description of this disclosure, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of this disclosure and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this disclosure. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0063] refer to Figure 2-Figure 30 This embodiment provides a display panel, including a flexible substrate 1, wherein the flexible substrate 1 includes a first side and a second side opposite to each other, wherein an OLED device 2 is provided on the first side, and a heat dissipation functional film layer 4 is directly adhered to the second side, or a thermal conductive film layer 3 and a heat dissipation functional film layer 4 are sequentially provided on the second side in a direction away from the flexible substrate 1, wherein the thermal conductive film layer 3 includes at least one sub-thermal conductive film layer stacked.

[0064] refer to Figure 1 In the related art, the effective heat dissipation functional film layer 4 is not in direct contact with the OLED display screen (that is, it is not in direct contact with the flexible substrate 1), and there are many plastic insulation layers in between (that is, thermal conductive film layers 3, each thermal conductive film layer has a different thermal conductivity, some film layers have poor thermal conductivity and strong thermal insulation performance), such as PSA (pressure sensitive adhesive) and PI (polyimide) FILM. The main purpose of the plastic insulation layer is to prevent the heat of other electronic components such as IC, CPU, etc. from diffusing to the screen. Therefore, the function achieved by the combination of the heat dissipation functional film layer 4 and the thermal conductive film layer 3 is actually to insulate the OLED screen and prevent the heat of other components from diffusing to the OLED screen, rather than to dissipate the heat generated by the OLED screen 2.

[0065] In this embodiment, all the thermally conductive film layers 3 between the heat dissipation functional film layer 4 and the flexible substrate 1 are removed, and the heat dissipation functional film layer 4 is directly adhered to the second side of the flexible substrate 1, or part of the thermally conductive film layer 3 is removed (the thermally conductive film layer 3 includes multiple sub-thermal conductive film layers, which refers to reducing the number of sub-thermal conductive film layers included in the thermally conductive film layer 3), leaving only a part of the sub-thermal conductive film layer between the flexible substrate 1 and the heat dissipation functional film layer 4, and the thermally conductive film layer 3 and the heat dissipation functional film layer 4 are sequentially arranged on the second side. The thermally conductive film layer 3 includes at least one sub-thermal conductive film layer arranged in a stacked manner. This is beneficial to reducing the temperature of the OLED device 2, slowing down the brightness decay of the OLED display panel, and extending the service life.

[0066] In an exemplary embodiment, the heat dissipation functional film layer 4 includes a high thermal conductivity adhesive, and the high thermal conductivity adhesive is made of one or more of acrylic resin, silicon-based material, thermal conductive silicone grease, and liquid metal.

[0067] The heat dissipation of the OLED device is achieved by using the high thermal conductivity adhesive with a high thermal conductivity coefficient, which accelerates the heat dissipation in a direction perpendicular to the flexible substrate and improves the overall heat dissipation effect of the display panel.

[0068] The thermal conductivity of the highly thermally conductive adhesive may vary depending on the material used. For example, the thermal conductivity of liquid metal is 80 W / m·k.

[0069] In an exemplary embodiment, the heat dissipation functional film layer 4 further includes a metal layer located on a side of the high thermal conductive adhesive away from the flexible substrate 1, Figure 7 This can further improve the overall heat dissipation effect of the display panel.

[0070] The function of the heat dissipation functional film layer 4 is to achieve heat dissipation. Its specific structural form can be various, and can include a single layer or multiple layers of heat dissipation film layers. In an exemplary embodiment, the heat dissipation functional film layer 4 includes one or more film layers made of Al, Cu, graphite sheets, and nano copper carbon.

[0071] In a display module including the display panel, an optical film layer 40 is further provided on the light-emitting side of the display panel, and a cover plate CG is further provided on the light-emitting side of the optical film layer 40. The optical film layer 40 may include a polarizer and a touch layer (but is not limited thereto). The OLED device 2 serves as a heat source, transferring heat to the light-emitting side and the backlight side, respectively. The thickness, thermal conductivity, and other parameters of each film layer located on the light-emitting side or the backlight side of the OLED device 2 are different, resulting in different surface temperatures of the corresponding film layers. The number of sub-thermal conductive film layers in the thermal conductive film layer and the specific structure of the sub-thermal conductive film layers can be selected based on the temperature of the light-emitting surface of the cover plate CG of the display module and the temperature of the bottom surface of the display module.

[0072] This method uses the heat transfer formula, and the heat flux density q0 is:

[0073] Total heat flux Where p is the heat generation power of the OLED device, s is the heat dissipation area, q1 is the heat flux density transferred to the light-emitting side, and q2 is the heat flux density transferred to the backlight side.

[0074] According to the third type of boundary conditions, the steady-state heat transfer resistance of the multilayer wall is: The heat transfer resistance R1 for transferring heat to the light-emitting side and the heat transfer resistance R2 for transferring heat to the backlight side can be obtained.

[0075] Wherein, x is the thickness of the film layer located on the light-emitting side or the backlight side of the OLED device, λ is the thermal conductivity of the film layer on the light-emitting side or the backlight side of the OLED device, and h is the air convection heat transfer coefficient.

[0076] When the temperature is in thermal equilibrium, the highest point is located at the OLED device (actually the light-emitting layer in the OLED device), x = 0, then according to the following formula and get That is, q1R1=q2R2; where a is the thickness at a first position on the light-emitting side of the OLED device (i.e., the distance between the OLED device and the first position), b is the thickness at a second position on the backlight side of the OLED device (i.e., the distance between the OLED device and the second position). λ1 is the thermal conductivity of the film layer on the light-emitting side of the OLED device, λ2 is the thermal conductivity of the film layer on the backlight side of the OLED device, and t ∞ is the ambient temperature.

[0077] According to the formula q1R1=q2R2 and q0=q1+q2, we can obtain:

[0078] According to the above formula, when x=a, the temperature of the first position

[0079] When x=b, the temperature of the second position

[0080] The following structural forms are selected for temperature calculation of each film layer:

[0081] Structure 1: The thermal conductive film layer 3 includes a sub-thermal conductive film layer, which is a back film layer (BF) 31 (no heat dissipation function film layer is provided), refer to Figure 2 .

[0082] Structure 2: The thermal conductive film layer 3 includes two sub-layer thermal conductive film layers, the two sub-layer thermal conductive film layers include a back film layer (BF) 31 and a mesh adhesive layer (Embo tape) 32 stacked, and the heat dissipation functional film layer 4 includes a graphite layer (Graphite sheet) and a copper metal layer (Cu) stacked. Figure 3 .

[0083] Structure 3: The thermal conductive film layer 3 includes two sub-layers of thermal conductive film layers, which include a back film layer (BF) 31 and a mesh adhesive layer (Embo tape) 32 stacked together. The heat dissipation functional film layer 4 includes a graphite layer (Graphite sheet) and a copper metal layer (Cu) stacked together. A mesh adhesive layer (Embo tape) and an Al plate are stacked on the side of the heat dissipation functional film layer 4 away from the flexible substrate 1. Figure 4 .

[0084] Structure 4: The thermal conductive film layer 3 includes two sub-layer thermal conductive film layers, the two sub-layer thermal conductive film layers include a stacked back film layer (BF) 31 and a mesh adhesive layer (Embo tape) 32, and the heat dissipation functional film layer 4 only includes an AL board, reference Figure 5 .

[0085] Structure 5: The thermal conductive film layer 3 includes a sub-thermal conductive film layer, the sub-thermal conductive film layer includes a mesh adhesive layer (Embo tape) 32, and the heat dissipation functional film layer includes an AL board, reference Figure 6 .

[0086] Structure 6: There is no thermal conductive film layer between the flexible substrate 1 and the heat dissipation functional film layer 4. The flexible substrate 1 is in direct contact with the heat dissipation functional film layer 4. The heat dissipation functional film layer 4 includes a stacked high thermal conductive adhesive and an AL plate. Figure 7 .

[0087] The thickness and thermal conductivity of each film layer structure are shown in Table 1 below:

[0088]

[0089] It should be noted that the high thermal conductivity adhesive in the above table is made of liquid metal, but is not limited to this. In actual applications, acrylic resin or the like can also be used to make the high thermal conductivity adhesive.

[0090] The calculated temperature values ​​are shown in Table 2 below:

[0091]

[0092] It should be noted that a backplane BP is provided on one side of the flexible substrate 1, an OLED light-emitting layer is provided on the backplane BP, an encapsulation layer TFE is provided on the light-emitting side of the OLED light-emitting layer, an optical film layer 40 is provided on the side of the encapsulation layer away from the OLED light-emitting layer, and a cover plate CG is provided on the side of the optical film layer 40 away from the OLED light-emitting layer. The above table does not indicate the specific surface temperature of each film layer.

[0093] Figure 8 The dot numbered 300 represents the temperature of the heat source (i.e., the temperature of the light-emitting layer of the OLED device), the dot numbered 200 represents the temperature of the top surface (i.e., the light-emitting surface of the cover plate) in the above six structures, and the dot numbered 100 represents the temperature of the bottom surface in the six structures.

[0094] From the above table and Figure 8 It can be obtained that, among the above structures, when structure six is ​​adopted, the temperature of the upper surface of the cover plate is the lowest.

[0095] On a white screen, the calculated value obtained by the above formula is compared with the measured value. Figure 9 As shown ( Figure 9 The measured and calculated values ​​of four structures, structure 1 to structure 4, were selected for comparison): Figure 9 The twill pattern represents the calculated value, and the dot pattern represents the measured value.

[0096] refer to Figure 9 It can be seen that for different structures, the temperature values ​​(calculated values) obtained by the above formula and the actually measured temperature values ​​(measured values) have the same change trend. For example, the measured value in structure one is 46.6, and the measured value in structure two is 44.4, and the temperature is decreasing. The calculated value in structure one is 43.45, and the calculated value in structure two is 43.41, and the temperature is also decreasing. Therefore, the calculated value obtained by the above formula is of guiding significance, and the corresponding sub-thermal conductive film layer can be increased or decreased according to the corresponding calculated value to meet the corresponding heat dissipation requirements.

[0097] When the display panel is used in a display screen, at room temperature of 25°C, the heating power P of the vehicle display screen is 21.84W. The thermal conductivity coefficients of the display screen's film stack structure and the thickness of each film layer are shown in the following table. The air convection heat transfer coefficient h is 10W / (m².k). Please calculate the maximum display screen temperature (heat source temperature, i.e., OLED device temperature) t, as well as the cover plate (CG) surface temperature t1 and the Al plate surface temperature t2.

[0098] The following table shows that the light-emitting side of the display panel is sequentially laminated with a polarizer pol, a first optical adhesive layer COA2, a touch substrate TSP, a second optical adhesive layer COA1, and a cover plate CG, and the backlight side of the display panel is sequentially laminated with a back film BF, a mesh adhesive layer EMBO, a foam adhesive layer FOAM, a graphite layer GRAPHITE, a double-sided adhesive layer DOUBLE TAPE, and an aluminum plate AL.

[0099]

[0100] Maximum temperature

[0101] Upper surface temperature

[0102] Lower surface temperature

[0103]

[0104] From the above formula, we obtain: R1=0.1100, R2=0.1022, q0=386.1181, t=45.4573, t1=43.6003, t2=45.0115.

[0105] Several structural forms in this embodiment are introduced below.

[0106] In an exemplary embodiment, the thermally conductive film layer 3 includes one or two film layers selected from the group consisting of a back film layer (BF) 31 , an Embo tape 32 , and a buffer layer 33 (eg, a foam layer).

[0107] Compared with traditional technologies, the thermally conductive film layer 3 not only omits the PSA (pressure-sensitive adhesive layer) and the PI (polyimide film layer), but also removes one of the back film layer (BF) 31, the mesh adhesive layer (Embo tape) 32, and the buffer layer 33. In this way, the heat generated by the OLED display panel during operation can be better transferred through the heat dissipation functional film layer 4, thereby helping to reduce the temperature of the OLED display panel.

[0108] In an exemplary embodiment, the thermal conductive film layer 3 includes the stacked back film layer (BF) 31 and / or the mesh adhesive layer (Embo tape) 32, and a buffer layer 33 is provided on the side of the heat dissipation functional film layer 4 away from the flexible substrate 1 (using a foam adhesive layer Foam, the foam adhesive layer Foam is bonded to one side of the heat dissipation functional film layer 4 through an adhesive layer (Adhesive layer). Figure 11 .

[0109] The contrast structure is Figure 1 The heat dissipation functional film layer 4 has a PSA (pressure sensitive adhesive layer) and a PI (polyimide film layer) above it. Figure 11 In the embodiment, the heat dissipation functional film layer 4 is a metal layer (Cu) with a thickness of 80 μm and a graphite sheet ( Figure 11 (not shown), the screen is lit at 800 nits for 1 hour, Figure 1 The screen brightness and surface temperature distribution corresponding to the structure in are as follows Figure 13 As shown, the temperature distribution is 38.9-45.2℃, Figure 11 The screen brightness and surface temperature distribution corresponding to the structure in are as follows Figure 12 As shown, the temperature distribution is 38.1-44.7℃, and the temperature drops by about 0.5℃.

[0110] After the OLED light-emitting layer and encapsulation layer are prepared on the OLED screen, in order to prevent the OLED screen from being scratched in the subsequent process, a temporary protective film is usually attached to the bottom of the flexible substrate 1, which is generally called a bottom film. The material of this film is usually plastic such as PI or PET, which has very poor thermal conductivity. In one embodiment of this embodiment, Figure 11 The back film BF is removed based on Figure 14 , relative to Figure 11 The structure is more conducive to the heat dissipation of the OLED panel.

[0111] In an exemplary embodiment, a heat insulation layer is provided on a side of the heat dissipation functional film layer 4 away from the flexible substrate 1 .

[0112] If there are electronic components under the heat dissipation functional film layer 4, such as the Tcon FPC required to drive the OLED screen, it is necessary to prevent the heat of the Tcon FPC from diffusing to the OLED display screen. A heat insulation layer can be added on the side of the heat dissipation functional film layer 4 away from the flexible substrate 1. The heat insulation layer can be made of insulating materials such as PSA / PI. Figure 15 The thermal insulation layer includes a pressure-sensitive adhesive layer (PSA) 5 and a polyimide layer (PI) 6.

[0113] If the display screen's mechanical vibration resistance meets the requirements, the foam layer for buffering can be omitted. Figure 16 .

[0114] refer to Figure 20-30 In an exemplary embodiment, the heat dissipation functional film layer 4 includes a temperature vapor chamber.

[0115] The setting of the temperature equalizer is beneficial to reducing the overall temperature of the OLED module (the temperature equalizer can achieve uniformity and cooling at the same time (neutralization of the high temperature part and the low temperature part, actually achieving cooling)) and improving the temperature uniformity within the surface.

[0116] It should be noted that heat pipes (Heatpipe) and vapor chambers (VC) are widely used in high-power or highly integrated electronic products. The vapor chamber is a vacuum cavity with a capillary microstructure on the inner wall. The basic principle and theoretical framework are the same as those of the heat pipe. The difference is that the heat conduction method is different. The heat pipe conduction is one-dimensional and linear, while the vapor chamber is two-dimensional and surface conduction. Specifically, after absorbing the heat from the chip, the liquid at the bottom of the vacuum cavity evaporates and diffuses into the vacuum cavity, conducting the heat to the heat dissipation fins, and then condenses into liquid and returns to the bottom. This evaporation and condensation process, similar to that of a refrigerator and air conditioner, circulates rapidly in the vacuum cavity, achieving a very high heat dissipation efficiency.

[0117] The heat spreader is a two-piece structure whose width can be customized arbitrarily and is theoretically unlimited. Due to its large area, its maximum heat transfer is also relatively large. Etching technology is used to etch bosses on the copper plate, which serve as support. A copper mesh is attached to the inside of the other copper plate as a capillary structure. The gaps between the copper pillars (i.e., the bosses) are the steam flow channels, and the copper mesh is the liquid return channel.

[0118] The VC temperature spreader is also a representative of phase change heat conduction. It is also a heat dissipation unit made of pure copper, which is internally sealed and hollow (the inner wall is not smooth and covered with capillary structures) and filled with condensate. However, its shape is not the flat "strip" of the heat pipe, but a wider flat "sheet". The working principle of the VC temperature spreader is similar to and different from that of the heat pipe, but generally includes four steps: conduction → evaporation → convection → solidification. When the VC evaporation section is heated, the liquid in the liquid absorption core on the inside of the evaporation section evaporates, the pressure here increases, and the steam is transferred to the condensation section under the action of the pressure difference. When the gas is transferred to the condensation section, it is condensed into liquid. The condensed liquid is transferred to the evaporation section by capillary force in the liquid absorption core, forming a cycle (the specific structural setting of the temperature spreader can refer to the relevant technology, and will not be repeated here).

[0119] In an exemplary embodiment, a plurality of heat dissipation columns 20 are provided on a side of the temperature vapor chamber away from the flexible substrate.

[0120] It should be noted that Figure 20-30 In the figure, the flexible substrate and OLED device are represented as a whole, that is, Figure 20-30 The display substrate is indicated by 10.

[0121] On the basis of the temperature spreader, heat dissipation columns 20 are added to further expand the heat dissipation area, which is beneficial to lowering the temperature of the OLED module, reducing the temperature difference within the surface of the OLED module, and improving the yellowing MURA (uneven brightness) phenomenon in the back fold area of ​​the PCB.

[0122] In an exemplary embodiment, the display panel includes a flexible circuit board 7 electrically connected via a chip-on-film, the flexible circuit board 7 is bent to a side of the temperature vapor chamber away from the flexible substrate, the orthographic projection of the flexible circuit board 7 on the temperature vapor chamber is located in a first area, and the heat dissipation column 20 is located in a second area of ​​the temperature vapor chamber adjacent to the first area.

[0123] The conventional heat dissipation method of OLED modules is to attach a heat dissipation film or heat dissipation aluminum plate to the non-display surface of the screen, and fold the PCB (flexible circuit board) back onto the aluminum plate. Figure 17 and Figure 18 As shown, because the PCB contains high-heat-generating devices such as chips, heat from the PCB 7 is transferred to the screen, causing temperature inconsistencies between the lower and upper ends of the screen. The upper end is cooler, while the lower end is hotter. Consequently, the brightness at the lower end decays faster than at the upper end, which can cause the image at the lower end to appear yellow over time. In this embodiment, the heat dissipation film layer 4 includes a vapor chamber. The flexible circuit board 7 is bent to the side of the vapor chamber away from the flexible substrate, improving the overall temperature uniformity of the display panel.

[0124] Will Figure 17 and Figure 19 For comparison, Figure 18 and Figure 20 By comparison, it can be seen that in this embodiment, the length of the flexible circuit board 7 (the length in the direction from the cover chip film to the flexible circuit board) is shortened, thereby reducing the area of ​​the positive projection of the flexible circuit board 7 on the display substrate 10, thereby reducing the temperature difference caused by the flexible circuit board 7.

[0125] For example, in order to reduce the length of the flexible circuit board 7 (the length in the direction from the COF to the flexible circuit board), the flexible circuit board can be made to have a multi-layer structure, or even the number of layers in the flexible circuit board can be increased. Figure 21 and Figure 22 , Figure 21In the flexible circuit board, a 4-layer structure is adopted (including two signal layers (signal routing layers), and a GND plane layer (ground layer) and a power plane layer (functional routing layer) located between the two signal routing layers). Figure 22 The flexible circuit board adopts an 8-layer structure (including four signal layers (signal routing layers), which are respectively the first signal routing layer, the second signal routing layer, the third signal routing layer and the fourth signal routing layer along the first direction, a GND plane layer (ground layer) is provided between the first signal routing layer and the second signal routing layer, a GND plane layer (ground layer) is provided between the third signal routing layer and the fourth signal routing layer, and a GND plane layer (ground layer) and a power plane layer (functional routing layer) are provided between the second signal routing layer and the third signal routing layer). Figure 22 The stacked structure in Figure 21 In the laminated structure, the length of the flexible circuit board 7 (the length in the direction from the COF to the flexible circuit board) is reduced by more than 50%, but is not limited thereto.

[0126] It should be noted that Figure 7 and Figure 8 In the flexible circuit board, the flexible circuit board includes a signal layer (signal wiring layer), a GND plane layer (ground layer), and a power plane layer (functional wiring layer).

[0127] In an exemplary embodiment, the height of the heat dissipation column 20 in a direction perpendicular to the flexible base (ie, perpendicular to the display substrate 10) increases sequentially from the second area to the first area. Figure 23 Due to the arrangement of the flexible circuit board 7, the temperature of the area close to the flexible circuit board is higher than the temperature of the area far from the flexible circuit board. The arrangement of the heat dissipation columns 20 in a direction perpendicular to the flexible substrate, in which the height increases successively from the second area to the first area, can reduce the temperature difference between the first area and the second area.

[0128] In an exemplary embodiment, the cross-sectional area of ​​the heat dissipation column in a direction parallel to the flexible substrate gradually decreases in a direction away from the flexible substrate. Figure 24 .

[0129] In an exemplary embodiment, the height of the heat dissipation column 20 in a direction perpendicular to the flexible substrate (i.e., perpendicular to the display substrate 10) increases gradually from the second region to the first region, and the cross-sectional area of ​​the heat dissipation column in a direction parallel to the flexible substrate gradually decreases in a direction away from the flexible substrate. Figure 25 .

[0130] In an exemplary embodiment, the distribution density of the heat dissipation columns increases in sequence from the second area to the first area. Figure 26 and Figure 27 .

[0131] In an exemplary embodiment, the flexible substrate is a curved surface structure that is curved in at least a first direction (i.e., the display substrate 10 is a curved surface structure that is curved in at least a first direction). Along the first direction, the distribution density of the heat dissipation columns 20 gradually increases from the two ends of the vapor chamber to the middle. Figure 28 and Figure 29 .

[0132] In an exemplary embodiment, the area of ​​the orthographic projection of the heat dissipation column 20 located in the middle area of ​​the temperature vapor chamber on the temperature vapor chamber is a first area, and the area of ​​the orthographic projection of the heat dissipation column 20 located in the edge area of ​​the temperature vapor chamber on the temperature vapor chamber is a second area. The first area is larger than the second area. Figure 28 and Figure 29 .

[0133] It should be noted that the size, spacing, height, diameter, etc. of the heat dissipation columns are determined according to the actual heat dissipation needs. The diameter is generally between 1 and 50 mm, the spacing between adjacent heat dissipation columns is generally between 1 and 30 mm, and the height of the heat dissipation columns is generally between 0.5 and 100 mm. The shape can be cylindrical (including cylinders with different upper and lower diameters), elliptical, square, rectangular, conical, etc. The distribution can be uniform or uneven, the height can be consistent or inconsistent, and can be upright or inclined.

[0134] In an exemplary embodiment, the flexible circuit board 7 is connected to the temperature plate through a connector 30, referring to Figure 30 .

[0135] The connecting member 30 may be a screw column, which prevents the flexible circuit board from directly contacting the temperature homogenizing plate.

[0136] In an exemplary embodiment, the heat dissipation column 20 is reused as the connecting member.

[0137] The present disclosure also provides a display module, comprising a cover plate and the display panel, and an optical film layer located between the cover plate and the display panel.

[0138] The temperature t1 at the first position on the light-emitting side of the OLED device satisfies the following formula:

[0139]

[0140] The temperature t2 of the second position located on the backlight side of the OLED device satisfies the following formula:

[0141]

[0142] R1 or R2 is obtained by the following formula:

[0143] q0 is obtained by the following formula: q0 = p / s

[0144] Wherein, q0 is the total heat flux density, p is the heat generation power of the display panel, s is the heat dissipation area of ​​the display panel, R1 is the thermal resistance of the light-emitting side of the OLED device, R2 is the thermal resistance of the backlight side of the OLED device, x is the distance between the first position or the second position and the OLED device, λ is the thermal conductivity of each film layer between the first position or the second position and the OLED device, h is the air convection heat transfer coefficient, t ∞ is the ambient temperature.

[0145] The calculation result of the above formula can be used as a reference to determine the number of sub-thermal conductive film layers included in the thermal conductive film layer and the specific material to be used.

[0146] It is understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present disclosure, and the present disclosure is not limited thereto. Those skilled in the art may make various modifications and improvements without departing from the spirit and substance of the present disclosure, and such modifications and improvements are also considered to be within the scope of protection of the present disclosure.

Claims

1. A display panel, wherein: The flexible substrate includes a first side and a second side opposite to each other, the first side is provided with an OLED device, the second side is directly attached with a heat dissipation functional film layer, or a heat conductive film layer and a heat dissipation functional film layer are sequentially provided on the second side in a direction away from the flexible substrate, the heat conductive film layer includes at least one sub-heat conductive film layer arranged in a stacked manner; The heat dissipation functional film layer includes a temperature homogenizing plate; A plurality of heat dissipation columns are provided on a side of the temperature homogenizing plate away from the flexible substrate; According to the temperature t1 at a first position on the light-emitting side of the OLED device and the temperature t2 at a second position on the backlight side of the OLED device, the number of sub-thermal conductive film layers included in the thermal conductive film layer and the specific material used can be obtained; The temperature t1 at the first position on the light-emitting side of the OLED device satisfies the following formula: The temperature t2 of the second position located on the backlight side of the OLED device satisfies the following formula: R1 or R2 is obtained by the following formula: q0 is obtained by the following formula: q0 = p / s Wherein, q0 is the total heat flux density, p is the heat generation power of the display panel, s is the heat dissipation area of ​​the display panel, R1 is the thermal resistance of the light-emitting side of the OLED device, R2 is the thermal resistance of the backlight side of the OLED device, and x i is the distance between the first position or the second position and the OLED device, λ i is the thermal conductivity of each film layer located between the first position or the second position and the OLED device, h is the air convection heat transfer coefficient, t ∞ is the ambient temperature.

2. The display panel according to claim 1, wherein The heat dissipation functional film layer includes a high thermal conductivity adhesive, and the high thermal conductivity adhesive is made of one or more of acrylic resin, silicon-based material, thermal grease, and liquid metal.

3. The display panel according to claim 2, wherein: The heat dissipation functional film layer further includes a metal layer located on a side of the high thermal conductive adhesive away from the flexible substrate.

4. The display panel according to claim 1, wherein: The heat dissipation functional film layer includes one or more film layers made of Al, Cu, graphite sheets, and nano copper carbon.

5. The display panel according to claim 1, wherein: The heat-conducting film layer includes one or two film layers among a back film layer, a grid adhesive layer and a buffer layer. The display panel according to claim 5 , wherein: The thermal conductive film layer includes the stacked back film layer and / or the grid adhesive layer, and a buffer layer is provided on a side of the heat dissipation functional film layer away from the flexible substrate.

7. The display panel according to claim 1, wherein: A heat insulation layer is provided on a side of the heat dissipation functional film layer away from the flexible substrate.

8. The display panel according to claim 1, wherein: The display panel includes a flexible circuit board electrically connected via a chip-on-film, the flexible circuit board is bent to a side of the temperature vapor chamber away from the flexible substrate, the orthographic projection of the flexible circuit board on the temperature vapor chamber is located in a first area, and the heat dissipation column is located in a second area of ​​the temperature vapor chamber adjacent to the first area.

9. The display panel according to claim 8, wherein: The height of the heat dissipation pillars in a direction perpendicular to the flexible substrate increases sequentially along a direction from the second area to the first area.

10. The display panel according to claim 1 or 8, wherein: The cross-sectional area of ​​the heat dissipation column in a direction parallel to the flexible substrate gradually decreases along a direction away from the flexible substrate.

11. The display panel according to claim 8 or 9, wherein: The distribution density of the heat dissipation columns increases sequentially along a direction from the second area to the first area.

12. The display panel according to claim 8 or 9, wherein: The flexible substrate is a curved surface structure that is bent in at least a first direction. Along the first direction, the distribution density of the heat dissipation columns gradually increases from the two ends of the temperature vapor chamber to the middle.

13. The display panel according to claim 12, wherein: The area of ​​the direct projection of the heat dissipation column located in the middle area of ​​the temperature homogenizing plate on the temperature homogenizing plate is a first area, and the area of ​​the direct projection of the heat dissipation column located in the edge area of ​​the temperature homogenizing plate on the temperature homogenizing plate is a second area, and the first area is greater than the second area.

14. The display panel according to claim 9, wherein: The flexible circuit board is connected to the temperature equalizing plate through a connector.

15. The display panel according to claim 14, wherein: The heat dissipation column is reused as the connecting piece.

16. A display module, wherein: comprising a cover plate and the display panel according to any one of claims 1 to 15, and an optical film layer located between the cover plate and the display panel, The temperature t1 at the first position on the light-emitting side of the OLED device satisfies the following formula: The temperature t2 of the second position located on the backlight side of the OLED device satisfies the following formula: R1 or R2 is obtained by the following formula: q0 is obtained by the following formula: q0 = p / s Wherein, q0 is the total heat flux density, p is the heat generation power of the display panel, s is the heat dissipation area of ​​the display panel, R1 is the thermal resistance of the light-emitting side of the OLED device, R2 is the thermal resistance of the backlight side of the OLED device, and x i is the distance between the first position or the second position and the OLED device, λ i is the thermal conductivity of each film layer located between the first position or the second position and the OLED device, h is the air convection heat transfer coefficient, t ∞ is the ambient temperature.

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