OLED module heat dissipation structure and OLED display screen

Abstract

The application relates to an OLED module heat dissipation structure and an OLED display screen, and relates to the technical field of OLED display. The application relates to an OLED module heat dissipation structure and an OLED display screen, and relates to the technical field of OLED display. The application relates to an OLED module heat dissipation structure and an OLED display screen, and relates to the technical field of OLED display. The application relates to an OLED module heat dissipation structure and an OLED display screen, and relates to the technical field of OLED display. The application relates to an OLED module heat dissipation structure and an OLED display screen, and relates to the technical field of OLED display. The application relates to an OLED module heat dissipation structure and an OLED display screen, and relates to the technical field of OLED display. The application relates to an OLED module heat dissipation structure and an OLED display screen, and relates to the technical field of OLED display. The application relates to an OLED module heat dissipation structure and an OLED display screen, and relates to the technical field of OLED display. The application relates to an OLED module heat dissipation structure and an OLED display screen, and relates to the technical field of OLED display. The application relates to an OLED module heat dissipation structure and an OLED display screen, and relates to the technical filed of OLED display. The application relates to an OLED module heat dissipation structure and an OLED display

Description

Technical Field

[0001] This application relates to the field of OLED display technology, and in particular to a heat dissipation structure for an OLED module and an OLED display screen. Background Technology

[0002] OLED displays have been widely used in consumer electronics such as smartphones, tablets, and TVs due to their excellent characteristics such as self-illumination, high contrast, and flexibility. During the electroluminescence process, the organic material layer of OLED devices generates significant heat. With the continuous improvement of screen brightness and refresh rate, as well as the popularization of high-performance applications such as HDR and games, the heat generation problem of OLED displays is becoming increasingly prominent.

[0003] Existing technologies involve OLED displays, screen components, and terminal devices. The OLED display includes a display body and a heat dissipation layer. In display mode, the display area of ​​the display body has a high-brightness region, whose brightness is greater than other areas of the display area. The heat dissipation layer is disposed on one side of the display body, and its position corresponds to the high-brightness region, so that the brightness decay rate of the high-brightness region is more consistent with that of other areas. This disclosure addresses the setting of a corresponding heat dissipation layer for the high-brightness region in commonly used software during display mode, thereby enhancing the heat dissipation capacity of the high-brightness region and making its heat dissipation capacity greater than that of other areas. In this way, the operating temperature and display brightness of different areas of the OLED display can be coordinated and matched, thereby achieving a more consistent brightness decay rate across different areas of the OLED display and solving the problem of localized display retention in OLED displays.

[0004] In the aforementioned and existing OLED display modules, air gaps are generally used to insulate the OLED to prevent backflow crosstalk caused by heat generated by the chip. However, due to the extremely low thermal conductivity of air, these air gaps, while blocking the backflow of heat from the chip, also block the heat dissipation path of the OLED display module's own light-emitting layer due to electroluminescence efficiency loss. This causes a continuous rise in localized temperature within the display module, resulting in color shift. If the air gap is removed and heat dissipation is directly achieved through the solid thermal conductivity of the mid-frame, the heat transferred from the chip to the mid-frame will cause thermal crosstalk to the display module, similarly leading to color shift and uneven brightness decay. Summary of the Invention

[0005] This application provides a heat dissipation structure for an OLED module and an OLED display screen, which can solve the problems of existing OLED display modules using air gaps for heat insulation, which makes it difficult to dissipate their own heat, and using conventional mid-frames for heat conduction and dissipation, which is subject to heat crosstalk from the chip.

[0006] The technical solution of this application is as follows: an OLED module heat dissipation structure, comprising: The middle frame has a chip on its outside, and the heat of the chip is conducted through the middle frame. The display module, the first heat conduction layer and the heat conduction buffer layer are stacked in the middle frame from top to bottom. The thermally conductive buffer layer includes a PCM buffer layer and a thermally conductive layer. One side of the PCM buffer layer and the thermally conductive layer are both disposed on the inner wall of the middle frame. The PCM buffer layer has a gap inside, and the thermally conductive layer is embedded in the gap. The other side of the PCM buffer layer and the thermally conductive layer are in contact with the first heat-conducting layer. The thermally conductive buffer layer directs the heat from the display module to the middle frame, while the PCM buffer layer buffers the return heat conducted from the chip to the middle frame.

[0007] By adopting the above solution, the thermally conductive layer in the thermally conductive buffer layer is embedded in the gaps of the PCM buffer layer, thereby forming a continuous solid thermal conductive path between the display module and the middle frame through the first heat-conducting layer and the thermally conductive layer. This allows the heat generated by the display module to be conducted to the middle frame along this path, solving the problem that the heat of the display module itself cannot be conducted out in the traditional air gap insulation solution. At the same time, one side of the PCM buffer layer is set on the inner wall of the middle frame and the other side is connected to the first heat-conducting layer. When the heat returning from the chip to the middle frame is transferred to the display module through the inner wall of the middle frame, the PCM buffer layer uses its characteristic of absorbing latent heat during the phase transition to buffer the heat returning from the chip, delay the rate at which the heat returns to the display module, and reduce the heat flow to the display module per unit time. This reduces the local temperature of the display module and reduces color shift and brightness attenuation inconsistencies caused by uneven temperature.

[0008] In one embodiment of this application, a second heat-conducting layer is provided on the outer side of the middle frame from top to bottom, and the second heat-conducting layer is used to further buffer the heat transferred by the chip.

[0009] By adopting the above scheme, the second heat conduction layer is placed outside the middle frame, on the path of heat transfer from the chip to the middle frame. Before reaching the middle frame, the heat of the chip is diffused in-plane through the second heat conduction layer, reducing the local heat flux density peak value transferred to the middle frame. After the heat passes through the middle frame, it is then absorbed and buffered by the PCM buffer layer in the thermal buffer layer. Thus, the heat of the chip is treated in two stages on the outside and inside of the middle frame. The former reduces the heat flux density, and the latter absorbs the heat peak value, reducing the heat flux density peak value of the heat returning to the display module.

[0010] In one embodiment of this application, both the first and second heat conduction layers include a graphene layer and a metal thermal conductive layer, wherein the graphene layer and the metal thermal conductive layer are stacked on top of each other, and the graphene layer is located on the side of the metal thermal conductive layer opposite to the middle frame.

[0011] By adopting the above scheme and setting the graphene layer, the received heat can be rapidly diffused in the horizontal direction; the metal thermal conductive layer has a high Z-axis thermal conductivity and structural stiffness, which can transfer heat in the thickness direction and provide structural support for the graphene layer. The graphene layer and the metal thermal conductive layer are stacked on each other, so that the first heat conduction layer and the second heat conduction layer have effective thermal conductivity in both the in-plane direction and the normal direction. The return heat must first pass through the metal thermal conductive layer and then be diffused and distributed by the graphene layer, which reduces the degree to which the return heat is concentrated to reach the display module.

[0012] In one embodiment of this application, the ratio K of the projected area S1 of the thermal conductive layer on the horizontal plane and the projected area S2 of the PCM buffer layer on the horizontal plane satisfies 0.05≤K≤0.1.

[0013] By adopting the above scheme, the projected area S1 of the heat-conducting layer on the horizontal plane determines the flux cross-section of the heat conduction from the heat-conducting layer to the middle frame of the display module, and the projected area S2 of the PCM buffer layer on the horizontal plane determines its interception coverage area for backflow heat and the total latent heat buffer capacity. By limiting the ratio K to the range of 0.05 to 0.1, it is possible to ensure that the PCM buffer layer has sufficient coverage area and buffer capacity to cope with the backflow heat of the chip while maintaining the effective heat dissipation of the display module by the heat-conducting layer.

[0014] In one embodiment of this application, the display module is provided with a cover glass, a touch layer, a light-emitting layer, a circuit layer and a back plate stacked from top to bottom, and the first heat conduction layer is bonded to the back plate.

[0015] By adopting the above scheme, the heat generated by the light-emitting layer is transferred downwards through the circuit layer and the backplate in sequence. Since the first heat-conducting layer is attached to the backplate, the heat is directly received by the first heat-conducting layer after passing through the backplate, which shortens the heat transfer path of the light-emitting layer to the first heat-conducting layer and reduces the thermal resistance of the intermediate interface. At the same time, since the first heat-conducting layer covers the entire bonding surface of the backplate, the concentrated heat generated by the light-emitting layer in the local high-brightness area is dispersed by in-plane heat-conducting layer when passing through the first heat-conducting layer, avoiding the occurrence of conduction bottleneck due to excessive local heat flux density in the heat-conducting layer.

[0016] In one embodiment of this application, the metal heat-conducting layer on the first heat-conducting layer has strip-shaped grooves on both sides along its width direction, and the upper end of the heat-conducting layer has a protrusion adapted to the shape of the inner wall of the strip-shaped groove. The protrusion passes through the gap and contacts the inner wall of the strip-shaped groove.

[0017] By adopting the above scheme, the protrusion at the upper end of the heat-conducting layer passes through the gap and enters the strip-shaped grooves opened on both sides of the metal heat-conducting layer on the first heat-conducting layer along its own width direction. The protrusion contacts the inner wall of the strip-shaped groove, thereby forming a direct solid surface contact between the heat-conducting layer and the metal heat-conducting layer, which improves the efficiency of heat transfer from the first heat-conducting layer to the heat-conducting layer through the metal heat-conducting layer. In addition, the protrusion is embedded in the strip groove after passing through the gap of the PCM buffer layer, so that the heat-conducting layer and the metal heat-conducting layer form a direct solid surface contact across the PCM buffer layer, which reduces the thermal resistance of the forward heat conduction path at the interface. Combined with the structure of the heat-conducting layer embedded in the gap of the heat-conducting buffer layer, it further ensures the continuity and low thermal resistance of the forward heat conduction path.

[0018] In one embodiment of this application, a heat conduction switching structure is further included, the heat conduction switching structure comprising: The sidewall ring has an annular cavity circumferentially formed inside the middle frame on the outside of the light-emitting layer. An annular window is formed on the side of the annular cavity near the light-emitting layer, and the sidewall ring is disposed in the annular window. The cavity ring is slidably sealed inside the annular cavity. Both the sidewall ring and the cavity ring include heat-conducting rings. The sidewall ring and the cavity ring are in contact with each other so that part of the heat of the light-emitting layer is conducted to the middle frame.

[0019] By adopting the above scheme, by contacting the sidewall ring and the cavity ring with each other, and both of them including heat-conducting rings, an auxiliary heat conduction path is established between the light-emitting layer and the middle frame through the solid contact surface between the heat-conducting ring in the sidewall ring and the heat-conducting ring in the cavity ring, so that part of the heat of the light-emitting layer can be conducted to the middle frame through this path.

[0020] In one embodiment of this application, a sensing cavity is formed between the upper end of the cavity ring and the inner wall of the upper end of the annular cavity, and a reset cavity is formed between the lower end of the cavity ring and the inner wall of the lower end of the annular cavity; The sensing cavity is equipped with a PCM sensing layer, and the reset cavity is equipped with an inert gas.

[0021] By adopting the above scheme, when the temperature of the middle frame rises to the phase change temperature of the PCM sensing layer, the PCM sensing layer changes from solid to liquid and its volume expands. Since the sensing cavity is a closed space between the upper end of the cavity ring and the inner wall of the cavity, the pressure generated by the volume expansion pushes the cavity ring to move towards the reset cavity along the axial direction. The reset cavity is located between the lower end of the cavity ring and the inner wall of the cavity. The inert gas inside is compressed when the cavity ring moves, the internal pressure increases and elastic potential energy is stored.

[0022] When the temperature of the middle frame drops below the phase change temperature of the PCM sensing layer, the PCM sensing layer re-solidifies and shrinks, the pressure inside the sensing cavity decreases, and the compressed inert gas in the reset cavity releases elastic potential energy, pushing the cavity ring back to its initial position. This achieves the switching of the relative positions between the side wall ring and the cavity ring, thereby switching the contact area of ​​the heat-conducting rings inside them and thus regulating the heat conduction efficiency of the mechanism.

[0023] In one embodiment of this application, the sidewall ring and cavity ring further include a heat insulation ring, and multiple heat insulation rings and heat conduction rings are provided and alternately arranged from top to bottom; The PCM sensing layer expands when heated to push the cavity ring, causing the heat-conducting rings in the cavity ring to interlock with the heat-conducting rings in the sidewall ring.

[0024] By adopting the above scheme, multiple heat insulation rings and heat conduction rings are arranged in the side wall ring and cavity ring, and are arranged alternately from top to bottom. At the same time, the thickness of the two rings is matched with the axial displacement of the cavity ring caused by the expansion of the PCM sensing layer. When the temperature of the middle frame is lower than the phase change temperature of the PCM sensing layer, the cavity ring is in the initial position. Each heat conduction ring in the cavity ring is aligned axially with the corresponding heat conduction ring in the side wall ring and makes face contact with each other, forming multiple sets of parallel solid heat conduction contact surfaces. Part of the heat of the light-emitting layer is conducted to the middle frame through the contact surfaces between the heat conduction rings.

[0025] When the PCM sensing layer expands and pushes the cavity ring to move by the thickness of one heat-conducting ring during heating, the heat-conducting ring in the cavity ring aligns with the heat-insulating ring in the sidewall ring. This alignment results in no longer a direct solid contact surface between the heat-conducting rings of each layer, and the heat conduction path of each layer is cut off by the heat-insulating ring. The overall thermal resistance between the sidewall ring and the cavity ring increases, thereby inhibiting the transfer of backflow heat from the middle frame to the light-emitting layer along this path. After the temperature of the middle frame drops, the cavity ring resets under the push of the inert gas, the heat-conducting rings realign, and the heat conduction path returns to its initial state, continuously conducting heat from the light-emitting layer to the middle frame, thus realizing the adaptive heat conduction switching of the device.

[0026] The second objective of this application is to provide an OLED display screen.

[0027] The technical solution is as follows: An OLED display screen includes an OLED module heat dissipation structure and a VC layer. The VC layer is located above the chip and is attached to the chip to transfer the heat of the chip to the middle frame.

[0028] By adopting the above scheme, the VC layer is located above the chip and is attached to the chip. The heat generated by the chip is diffused along the in-plane direction by the VC layer and transferred to the middle frame. This allows the heat of the chip to be homogenized before reaching the middle frame, reducing the local temperature peak of the corresponding chip area on the middle frame. At the same time, when the middle frame receives the heat homogenized by the VC layer and transfers it to the display module, the local heat flux density peak of the PCM buffer layer in the thermal buffer layer of the OLED module heat dissipation structure is reduced accordingly, and its effective buffering time is extended. In addition, the VC layer performs heat source homogenization on the chip side, and the OLED module heat dissipation structure performs backflow heat buffering and forward heat dissipation on the display module side. Both reduce the backflow heat reaching the display module on both sides of the heat transfer path.

[0029] In summary, this application includes at least one of the following beneficial technical effects: by setting a thermally conductive buffer layer composed of a PCM buffer layer and a thermally conductive layer inside the middle frame, with the thermally conductive layer embedded in the gaps of the PCM buffer layer, the forward thermal conduction path and the reflow heat buffer area coexist in the same layer structure and are spatially independent of each other. The thermally conductive layer forms a continuous solid thermal conduction path between the display module and the middle frame to dissipate the heat generated by the display module itself. The PCM buffer layer uses the latent heat absorption characteristics of phase change to buffer the reflow heat transferred by the chip through the middle frame. Thus, without relying on air gap insulation, the forward heat dissipation of the display module and the suppression of the chip's reflow heat are achieved simultaneously, solving the problem of the contradiction between heat dissipation and insulation requirements in the prior art.

[0030] By setting a heat conduction switching structure consisting of a sidewall ring and a cavity ring circumferentially around the outer surface of the light-emitting layer inside the middle frame, the heat conduction ring and the heat insulation ring in the sidewall ring and the cavity ring are alternately arranged from top to bottom. When the temperature of the middle frame rises, the PCM sensing layer in the sensing cavity expands and pushes the cavity ring to move axially, so that the heat conduction ring in the cavity ring and the heat conduction ring in the sidewall ring change from an aligned state to an interleaved state. The heat conduction path of each layer is cut off by the heat insulation ring, and the thermal resistance between the sidewall ring and the cavity ring increases accordingly. When the temperature of the middle frame drops, the inert gas compressed in the reset cavity releases elastic potential energy and pushes the cavity ring back to its initial position. The heat conduction ring is realigned and the heat conduction path is restored. This realizes the adaptive switching of the auxiliary heat conduction path between the light-emitting layer and the middle frame sidewall between the heat conduction state and the heat insulation state. The switching action of the heat conduction switching structure is driven by the phase change expansion of the PCM sensing layer and the elastic recovery of the inert gas, and does not depend on the external power input.

[0031] By setting a second heat conduction layer outside the middle frame, a heat conduction buffer layer inside the middle frame, and a VC layer above the chip, the VC layer transfers the heat from the chip to the middle frame after in-plane heat homogenization to reduce the local heat flux density peak. The second heat conduction layer diffuses the heat in-plane for a second time outside the middle frame. The PCM buffer layer in the heat conduction buffer layer absorbs and buffers the latent heat of the residual return heat passing through the middle frame inside the middle frame. The three layers are arranged sequentially along the heat transfer path from the chip to the display module, and the return heat is reduced step by step at three positions: the heat source end, the outside of the middle frame, and the inside of the middle frame, thereby gradually reducing the heat flux density of the return heat. Attached Figure Description

[0032] Figure 1 This is a cross-sectional view of a heat dissipation structure for an OLED module provided in an embodiment of this application; Figure 2 yes Figure 1 An enlarged schematic diagram of part A in the middle; Figure 3 yes Figure 1 Enlarged diagram of part B.

[0033] Explanation of reference numerals in the attached drawings: 1. Mid-frame; 11. Display module; 111. Cover glass; 112. Touch layer; 113. Light-emitting layer; 114. Circuit layer; 115. Backplate; 12. First heat conduction layer; 13. Thermal buffer layer; 131. PCM buffer layer; 1311. Gap; 132. Thermally conductive layer; 1321. Protrusion; 14. Second heat conduction layer; 15. Graphene layer; 16. Metal thermally conductive layer; 161. Strip groove; 17. Annular cavity; 18. Annular window; 2. Thermal switching structure; 21. Side wall ring; 22. Cavity ring; 23. Thermally conductive ring; 24. PCM sensing layer; 25. Inert gas; 26. Thermal insulation ring; 3. VC layer; 4. Chip. Detailed Implementation

[0034] The following is in conjunction with the appendix Figures 1-3 This application provides a further detailed description of an OLED module heat dissipation structure and an OLED display screen.

[0035] An OLED module heat dissipation structure provided in this application embodiment includes: a middle frame 1.

[0036] The outer side of the middle frame 1 is provided with a chip 4, and the heat of the chip 4 is conducted through the middle frame 1. The middle frame 1 is provided with a display module 11, a first heat conduction layer 12 and a heat conduction buffer layer 13 stacked from top to bottom inside the middle frame 1. The thermally conductive buffer layer 13 includes a PCM buffer layer 131 and a thermally conductive layer 132. One side of the PCM buffer layer 131 and the thermally conductive layer 132 are both disposed on the inner wall of the middle frame 1. A gap 1311 is opened inside the PCM buffer layer 131, and the thermally conductive layer 132 is embedded in the gap 1311. The other side of the PCM buffer layer 131 and the thermally conductive layer 132 are in contact with the first heat-conducting layer 12. The heat conduction buffer layer 13 conducts heat from the display module 11 to the middle frame 1 through the heat conduction layer 132, and at the same time buffers the return heat conducted to the middle frame 1 by the PCM buffer layer 131, so that the heat conduction layer 132 and the PCM buffer layer 131 respectively undertake the forward heat conduction and return heat buffering functions in the same layer structure.

[0037] In this embodiment, the middle frame 1 can be made of aluminum alloy with a wall thickness of 3mm to 8mm, and the PCM (Phase Change Material) buffer layer 131 can be made of paraffin-based phase change material with a phase change temperature of 40℃ to 55℃, a latent heat of phase change of 150 to 250J / g, and a thickness of 0.1mm to 0.5mm.

[0038] The side of the middle frame 1 is in contact with the outer shell of the terminal device. The heat from the display module 11, which is conducted to the middle frame 1 via the heat-conducting layer 132, diffuses to the side along the in-plane direction of the middle frame 1 and is dissipated to the environment through the outer shell. Among them, the paraffin-based phase change material in the PCM buffer layer 131 can be encapsulated in the form of microcapsules, with the phase change material encapsulated inside the microcapsule shell. The thermal conductive layer 132 can be made of copper pillars with a thermal conductivity of not less than 350 W / (m·K), and its height along the normal direction of the middle frame 1 is consistent with the thickness of the PCM buffer layer 131.

[0039] The thermally conductive layer 132 is embedded in the gap 1311 of the PCM buffer layer 131. The cross-sectional shape of the gap 1311 matches the cross-sectional shape of the thermally conductive layer 132. The thermally conductive layer 132 and the inner wall of the gap 1311 are filled with an interference fit or thermally conductive adhesive to reduce the interfacial thermal resistance.

[0040] The thickness of the first heat conduction layer 12 can be 0.02mm to 0.1mm, covering the back of the display module 11 and adhering to the upper surface of the heat conduction buffer layer 13.

[0041] It should be noted that, in the working state, the heat generated by the display module 11 is diffused through the first heat conduction layer 12 and then conducted to the middle frame 1 through the heat conduction layer 132 in a solid conduction manner; when the heat of the chip 4 is transferred to the heat conduction buffer layer 13 through the inner wall of the middle frame 1, the PCM buffer layer 131 changes from solid to liquid after reaching the phase change temperature, absorbs latent heat, thereby slowing down the rate at which the return heat is transferred to the display module 11.

[0042] A second heat-conducting layer 14 is provided on the outside of the middle frame 1 from top to bottom. The second heat-conducting layer 14 is used to further buffer the heat transferred by the chip 4.

[0043] In this embodiment, the second heat-conducting layer 14 is disposed on the lower surface of the outer wall of the middle frame 1. It can be bonded to the outer wall of the middle frame 1 by thermally conductive double-sided adhesive or pressure-sensitive adhesive, so that the thermal resistance of the bonding interface between the second heat-conducting layer 14 and the middle frame 1 is not greater than 0.1℃·cm² / W.

[0044] The planar dimensions of the second heat-conducting layer 14 match the planar dimensions of the corresponding area on the outer wall of the middle frame 1. Its coverage area is not less than three times the projected area of ​​the chip 4 on the horizontal plane. Before the heat generated by the chip 4 reaches the middle frame 1, it first spreads evenly in the in-plane direction through the second heat-conducting layer 14, so that the heat flux density distribution reaching the outer wall of the middle frame 1 tends to be uniform. Then, it is conducted through the wall of the middle frame 1 to the PCM buffer layer 131 side of the thermally conductive buffer layer 13, where the latent heat is absorbed by the PCM buffer layer 131.

[0045] The first heat conduction layer 12 and the second heat conduction layer 14 both include a graphene layer 15 and a metal heat conduction layer 16. The graphene layer 15 and the metal heat conduction layer 16 are stacked on top of each other, and the graphene layer 15 is located on the side of the metal heat conduction layer 16 away from the middle frame 1.

[0046] In this embodiment, the graphene layer 15 is a multilayer graphene film with a thickness of 0.017 mm to 0.05 mm, an in-plane thermal conductivity of 1000 to 1500 W / (m·K), and a normal thermal conductivity of 5 to 20 W / (m·K).

[0047] The metal thermally conductive layer 16 is made of copper foil with a thickness of 0.01 mm to 0.035 mm and a thermal conductivity of 380 to 400 W / (m·K). The graphene layer 15 and the metal thermally conductive layer 16 are bonded together by hot pressing or thermally conductive adhesive, with an interfacial thermal resistance of no more than 0.05 °C·cm² / W. The graphene layer 15 is located on the side of the metal thermally conductive layer 16 away from the middle frame 1. Specifically, in the first heat-conducting layer 12, the graphene layer 15 faces the back plate 115, and the metal thermally conductive layer 16 faces the heat-conducting buffer layer 13; in the second heat-conducting layer 14, the graphene layer 15 faces the chip 4, and the metal thermally conductive layer 16 faces the outer wall of the middle frame 1. Thus, heat is first rapidly diffused in the in-plane direction by the graphene layer 15, and then transferred along the normal direction by the metal thermally conductive layer 16 to the next layer structure.

[0048] The ratio K of the projected area S1 of the heat-conducting layer 132 on the horizontal plane and the projected area S2 of the PCM buffer layer 131 on the horizontal plane satisfies 0.05≤K≤0.1.

[0049] In this embodiment, the projected area S2 of the PCM buffer layer 131 on the horizontal plane is the sum of the planar area of ​​the entire thermally conductive buffer layer 13 minus the sum of the projected areas of all thermally conductive layers 132. That is, S2 is equal to the total area of ​​the thermally conductive buffer layer 13 supported by the inner wall of the middle frame 1 minus the sum of the projected areas S1 of all thermally conductive layers 132.

[0050] Specifically, when K=0.05, the heat-conducting layer 132 occupies approximately 4.76% of the total area of ​​the heat-conducting buffer layer 13, and the PCM buffer layer 131 occupies approximately 95.24%; when K=0.1, the heat-conducting layer 132 occupies approximately 9.09%, and the PCM buffer layer 131 occupies approximately 90.91%. In practical applications, when the heat dissipation power density of the display module 11 is 0.02~0.05W / cm², a K value of 0.05 is sufficient to meet the forward heat dissipation requirements; when the heat dissipation power density is 0.05~0.1W / cm², a K value of 0.08~0.1 is used to increase the forward heat conduction flux. When K is less than 0.05, the total projected area of ​​the heat-conducting layer 132 is too small, and the forward heat conduction cross section is insufficient to dissipate the working heat of the display module 11; when K is greater than 0.1, the coverage area of ​​the PCM buffer layer 131 is relatively reduced, and its interception area for backflow heat and total latent heat capacity are reduced, resulting in insufficient buffering effect.

[0051] The display module 11 is provided with a cover glass 111, a touch layer 112, a light-emitting layer 113, a circuit layer 114 and a back plate 115 stacked from top to bottom, and the first heat conduction layer 12 is bonded to the back plate 115.

[0052] In this embodiment, the back plate 115 is made of polyimide (PI) film or ultra-thin glass substrate with a thickness of 0.01mm to 0.05mm. Its lower surface is connected to the first heat conduction layer 12 by thermally conductive adhesive or direct bonding, and the interface thermal resistance is not greater than 0.08℃·cm² / W.

[0053] The metal heat-conducting layer 16 on the first heat-conducting layer 12 has strip-shaped grooves 161 on both sides along its width direction. The upper end of the heat-conducting layer 132 has a protrusion 1321 that matches the shape of the inner wall of the strip-shaped groove 161. The protrusion 1321 passes through the gap 1311 and contacts the inner wall of the strip-shaped groove 161.

[0054] In this embodiment, the metal heat-conducting layer 16 in the first heat-conducting layer 12 can be a copper foil layer with a thickness of 0.01mm to 0.035mm. The strip groove 161 is opened on both sides along the width direction of the metal heat-conducting layer 16 and extends along the length direction of the metal heat-conducting layer 16. The depth of the groove can be 0.005mm to 0.02mm and the width can be 0.3mm to 1.0mm.

[0055] The protrusion 1321 at the upper end of the heat-conducting layer 132 is adapted to the shape of the inner wall of the strip groove 161. The cross-sectional shape of the protrusion 1321 is rectangular or trapezoidal. The height of the protrusion 1321 is equal to the depth of the strip groove 161. The difference between the width of the protrusion 1321 and the width of the strip groove 161 is no more than 0.05mm, so as to achieve clearance fit or transition fit and ensure that the actual contact area between the protrusion 1321 and the inner wall of the strip groove 161 is not less than 80% of the total area of ​​the inner wall of the groove.

[0056] The protrusion 1321 passes through the gap 1311 of the PCM buffer layer 131 and is embedded in the strip groove 161. The cross-sectional dimension of the gap 1311 at the point where the protrusion 1321 passes through can be 0.05mm to 0.2mm larger than the cross-sectional dimension of the protrusion 1321, so as to avoid extrusion interference between the protrusion 1321 and the PCM buffer layer 131.

[0057] It also includes a heat conduction switching structure 2, which includes a side wall ring 21 and a cavity ring 22. An annular cavity 17 is provided circumferentially outside the light-emitting layer 113 inside the middle frame 1. An annular window 18 is provided on the side of the annular cavity 17 near the light-emitting layer 113. The side wall ring 21 is disposed in the annular window 18. The cavity ring 22 is slidably sealed inside the annular cavity 17. Both the side wall ring 21 and the cavity ring 22 include heat conduction rings 23. The side wall ring 21 and the cavity ring 22 are in contact with each other so that part of the heat of the light-emitting layer 113 is conducted to the middle frame 1.

[0058] In this embodiment, the annular cavity 17 is circumferentially opened outside the light-emitting layer 113 along the inner side of the middle frame 1. The radial cross-section of the annular cavity 17 is rectangular, and its radial width can be 1.0mm to 3.0mm and its axial height can be 2.0mm to 5.0mm.

[0059] The annular window 18 is opened along the side of the annular cavity 17 near the light-emitting layer 113, and the axial height of the annular window 18 is equal to or slightly smaller than the axial height of the annular cavity 17.

[0060] A sidewall ring 21 is disposed in an annular window 18. The outer ring surface of the sidewall ring 21 is fixed to the inner wall of the annular window 18 by thermally conductive adhesive or interference fit. The inner ring surface of the sidewall ring 21 faces the light-emitting layer 113. The inner ring surface of the sidewall ring 21 is connected to the outer edge of the light-emitting layer 113 by thermally conductive filling material to achieve heat transfer.

[0061] The heat-conducting ring 23 in the sidewall ring 21 and the cavity ring 22 can be made of copper or aluminum with a thermal conductivity of not less than 200 W / (m·K). In the initial state, the end face of the cavity ring 22 facing the sidewall ring 21 is in contact with the corresponding end face of the sidewall ring 21, and the contact surface pressure is 0.01 to 0.05 MPa.

[0062] A sensing cavity is formed between the upper end of the cavity ring 22 and the inner wall of the upper end of the annular cavity 17, and a reset cavity is formed between the lower end of the cavity ring 22 and the inner wall of the lower end of the annular cavity 17. A PCM sensing layer 24 is provided inside the sensing cavity, and an inert gas 25 is provided inside the reset cavity.

[0063] In this embodiment, the sensing cavity is located between the upper end of the cavity ring 22 and the inner wall of the annular cavity 17. Its axial length can be 0.5mm to 2.0mm, and its radial width is consistent with the radial width of the annular cavity 17.

[0064] The PCM sensing layer 24 can be made of low-melting-point paraffin wax, and the phase change temperature can be 45℃~60℃. This phase change temperature is 5℃~15℃ higher than the phase change temperature of the PCM buffer layer 131, so that the response of the heat conduction switching structure 2 lags behind the buffering action of the PCM buffer layer 131. The volume expansion rate of the PCM sensing layer 24 can be 8%~15%, and the axial displacement generated after the complete phase change is 0.1mm~0.5mm.

[0065] For example, when the axial length of the sensing cavity is 1.0 mm and the cross-sectional area is S, the volume of the sensing cavity is 1.0S mm³. When the PCM sensing layer (24) fills the entire sensing cavity and the volume expansion rate is 10%, the expansion volume is 0.1S mm³. Under the condition that the cross-sectional area of ​​the cavity ring 22 is S, the axial displacement is 0.1S / S = 0.1 mm. At this time, the axial thickness of the heat-conducting ring 23 and the heat-insulating ring 26 can be set to 0.1 mm to achieve complete interleaving.

[0066] The reset chamber is located between the lower end of the cavity ring 22 and the inner wall of the annular cavity 17. In the initial state, the axial length of the reset chamber is 1.0 mm to 3.0 mm. The inert gas 25 filled inside is nitrogen or argon, and the initial pressure is 0.1 to 0.3 MPa.

[0067] Specifically, when the PCM sensing layer 24 fully expands, the pressure of the inert gas 25 in the reset cavity rises to 0.15–0.5 MPa. The restoring force generated by this pressure is sufficient to push the cavity ring 22 back to its initial position after the PCM sensing layer 24 solidifies and contracts. The phase change temperature of the PCM sensing layer 24 must meet the following conditions: the temperature should be higher than the average temperature of the middle frame 1 of the display module 11 under normal operating conditions, and lower than the peak temperature that the middle frame 1 can reach due to the continuous high load operation of the chip 4, so that the heat conduction switching structure 2 will only trigger the switching action when the temperature of the middle frame 1 rises abnormally.

[0068] The sidewall ring 21 and the cavity ring 22 also include a heat insulation ring 26. Multiple heat insulation rings 26 and heat conduction rings 23 are provided and are arranged alternately from top to bottom. When the PCM sensing layer 24 is heated, it expands to push the cavity ring 22, so that the heat conduction rings 23 in the cavity ring 22 and the heat conduction rings 23 in the sidewall ring 21 are interleaved.

[0069] In this embodiment, 3 to 8 heat-conducting rings 23 and heat-insulating rings 26 are provided in the sidewall ring 21 and the cavity ring 22, and are arranged alternately from top to bottom. The axial thickness of each heat-conducting ring 23 and each heat-insulating ring 26 is equal, which is 0.1 mm to 0.5 mm, and is equal to the axial displacement of the cavity ring 22 when the PCM sensing layer 24 is fully expanded.

[0070] The heat-conducting ring 23 can be made of copper or aluminum, with a thermal conductivity of not less than 200 W / (m·K); Among them, the heat insulation ring 26 is made of polyimide, zirconia ceramic or aerogel composite material, with a thermal conductivity of no more than 0.5 W / (m·K), and the difference in thermal conductivity between the heat conduction ring 23 and the heat insulation ring 26 is no less than two orders of magnitude.

[0071] The arrangement order of the heat-conducting ring 23 and the heat-insulating ring 26 in the sidewall ring 21 is the same as that in the cavity ring 22. That is, in the initial state, the nth heat-conducting ring 23 in the sidewall ring 21 and the nth heat-conducting ring 23 in the cavity ring 22 are aligned one by one in the axial direction.

[0072] Specifically, when the cavity ring 22 moves axially by one ring layer thickness, the nth heat-conducting ring 23 in the cavity ring 22 aligns with the nth heat-insulating ring 26 in the sidewall ring 21, and the nth heat-insulating ring 26 in the cavity ring 22 aligns with the (n+1)th heat-conducting ring 23 in the sidewall ring 21. Thus, each contact layer is in contact with the heat-conducting ring 23 and the heat-insulating ring 26. The low thermal conductivity of the heat-insulating ring 26 cuts off the heat transfer path at this layer. Each heat-conducting ring 23 and the heat-insulating ring 26 are fixed together by hot pressing or nesting to ensure that the ring layers of the sidewall ring 21 and the cavity ring 22 do not separate or shift relative to each other during the sliding process.

[0073] The second objective of this application is to provide an OLED display screen.

[0074] The technical solution is as follows: an OLED display screen includes an OLED module heat dissipation structure and a VC layer 3. The VC layer 3 is located above the chip 4 and is attached to the chip 4 to transfer the heat of the chip 4 to the middle frame 1.

[0075] In this embodiment, the VC (Vapor Chamber) layer 3 is a heat exchanger plate, which has a capillary wick structure and a working fluid inside. The working fluid is deionized water or low-boiling-point fluorinated liquid, and the capillary wick structure is sintered copper powder or copper mesh. The overall thickness of the VC layer 3 is 0.2mm to 0.4mm.

[0076] The power density of chip 4 when running at full load is 1 to 5 W / cm². After being heated in-plane by VC layer 3, the heat flux density transferred to the outer wall of the middle frame 1 is reduced to 0.1 to 0.5 W / cm². After being conducted through the wall of the middle frame 1, the heat is gradually reduced by passing through the PCM buffer layer 131 of the second heat conduction layer 14 and the heat conduction buffer layer 13 before reaching the display module 11.

[0077] In summary, this application integrates the functions of forward heat dissipation of the display module 11 and backflow heat buffering of the chip 4 by setting a thermally conductive buffer layer 13 containing a thermally conductive layer 132 and a PCM buffer layer 131 inside the middle frame 1. By setting a thermally conductive switching structure 2 with alternating thermally conductive rings 23 and thermally insulating rings 26, the adaptive thermal conduction-thermal insulation switching of the auxiliary thermal conduction path in the side wall direction of the middle frame 1 is realized. Through the step-by-step cooperation of the VC layer 3, the second heat conduction layer 14 and the thermally conductive buffer layer 13, a multi-level thermal management link from the chip 4 end to the display module 11 end is constructed, which solves the technical problem that the existing OLED display module 11 cannot balance heat dissipation and thermal insulation.

[0078] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A heat dissipation structure for an OLED module, characterized in that, include: The middle frame (1) has a chip (4) on its outside. The heat of the chip (4) is conducted through the middle frame (1). The middle frame (1) has a display module (11), a first heat conduction layer (12) and a heat conduction buffer layer (13) stacked from top to bottom inside the middle frame (1). The thermally conductive buffer layer (13) includes a PCM buffer layer (131) and a thermally conductive layer (132). One side of the PCM buffer layer (131) and the thermally conductive layer (132) are both disposed on the inner wall of the middle frame (1). A gap (1311) is opened inside the PCM buffer layer (131), and the thermally conductive layer (132) is embedded in the gap (1311). The other side of the PCM buffer layer (131) and the thermally conductive layer (132) are in contact with the first heat-conducting layer (12). The thermally conductive buffer layer (13) conducts the heat of the display module (11) to the middle frame (1) through the thermally conductive layer (132), and at the same time buffers the return heat of the chip (4) to the middle frame (1) through the PCM buffer layer (131).

2. The heat dissipation structure for an OLED module according to claim 1, characterized in that: The outer side of the middle frame (1) is provided with a second heat conduction layer (14) from top to bottom. The second heat conduction layer (14) is used to further buffer the heat transferred by the chip (4).

3. The heat dissipation structure for an OLED module according to claim 2, characterized in that: The first heat conduction layer (12) and the second heat conduction layer (14) both include a graphene layer (15) and a metal heat conduction layer (16). The graphene layer (15) and the metal heat conduction layer (16) are stacked on each other, and the graphene layer (15) is located on the side of the metal heat conduction layer (16) away from the middle frame (1).

4. The heat dissipation structure for an OLED module according to claim 1, characterized in that: The ratio K of the projected area S1 of the heat-conducting layer (132) on the horizontal plane and the projected area S2 of the PCM buffer layer (131) on the horizontal plane satisfies 0.05≤K≤0.

1.

5. The heat dissipation structure for an OLED module according to claim 1, characterized in that: The display module (11) is provided with a cover glass (111), a touch layer (112), a light-emitting layer (113), a circuit layer (114) and a back plate (115) stacked from top to bottom, and the first heat conduction layer (12) is bonded to the back plate (115).

6. The heat dissipation structure for an OLED module according to claim 3, characterized in that: The metal heat-conducting layer (16) on the first heat-conducting layer (12) has strip-shaped grooves (161) on both sides along its width direction. The upper end of the heat-conducting layer (132) has a protrusion (1321) that matches the shape of the inner wall of the strip-shaped groove (161). The protrusion (1321) passes through the gap (1311) and contacts the inner wall of the strip-shaped groove (161).

7. The heat dissipation structure for an OLED module according to claim 5, characterized in that, It also includes a heat conduction switching structure (2), which comprises: Side wall ring (21), the middle frame (1) has an annular cavity (17) circumferentially formed outside the light-emitting layer (113) inside, the annular cavity (17) has an annular window (18) on the side close to the light-emitting layer (113), and the side wall ring (21) is disposed in the annular window (18); The cavity ring (22) is slidably sealed inside the annular cavity (17). Both the side wall ring (21) and the cavity ring (22) include a heat-conducting ring (23). The side wall ring (21) and the cavity ring (22) are in contact with each other so that part of the heat of the light-emitting layer (113) is conducted to the middle frame (1).

8. The heat dissipation structure for an OLED module according to claim 7, characterized in that: A sensing cavity is formed between the upper end of the cavity ring (22) and the inner wall of the upper end of the annular cavity (17), and a reset cavity is formed between the lower end of the cavity ring (22) and the inner wall of the lower end of the annular cavity (17). The sensing cavity is provided with a PCM sensing layer (24), and the reset cavity is provided with an inert gas (25).

9. The heat dissipation structure for an OLED module according to claim 8, characterized in that: The sidewall ring (21) and cavity ring (22) also include a heat insulation ring (26), and multiple heat insulation rings (26) and heat conduction rings (23) are provided and are arranged alternately from top to bottom; The PCM sensing layer (24) expands when heated to push the cavity ring (22), causing the heat-conducting ring (23) in the cavity ring (22) to interlock with the heat-conducting ring (23) in the sidewall ring (21).

10. An OLED display screen, characterized in that: Includes an OLED module heat dissipation structure as described in any one of claims 1-9 and a VC layer (3), wherein the VC layer (3) is located above the chip (4) and is attached to the chip (4) to transfer the heat of the chip (4) to the middle frame (1).

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