CN114967247A

CN114967247A - Backlight assembly and display module

Info

Publication number: CN114967247A
Application number: CN202110223715.3A
Authority: CN
Inventors: 张二帽; 张冬冬; 李强; 邱红兵; 徐雷
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2021-02-27
Filing date: 2021-02-27
Publication date: 2022-08-30

Abstract

The application discloses backlight unit and display module assembly. The backlight assembly includes: a light source and a flexible circuit board; the lamp source is arranged on the flexible circuit board. The flexible circuit board comprises a first wiring layer, a first grounding layer and a second grounding layer; the flexible circuit board is provided with a first side and a second side which are opposite, the first grounding layer and the first routing layer are both positioned on the first side of the flexible circuit board, and the first grounding layer is continuously arranged around the first routing layer; the second ground layer is located on the second side of the flexible circuit board. The first grounding layer and the second grounding layer are electrically connected with the grounding pin of the flexible circuit board. Based on the first grounding layer and the second grounding layer, the static electricity can be timely conducted to the grounding pin of the flexible circuit board outside the iron frame required by the existing backlight assembly, so that the possibility of conducting the static electricity in the reflecting film is reduced, and the damage of the static electricity to the backlight assembly is reduced.

Description

Backlight assembly and display module

Technical Field

The application relates to the technical field of backlight assemblies, in particular to a backlight assembly and a display module.

Background

In the lcd module, the lcd panel cannot emit light, and thus, the lcd panel needs to be used in conjunction with the backlight assembly. The backlight assembly is internally provided with a reflecting film, and a metal layer is clamped in the middle of the reflecting film to reflect light rays emitted by the lamp source. In the process of performing an ESD (Electro-Static Discharge) test, Static electricity is easily conducted to a lamp or a display IC through a metal layer of a reflective film, which causes problems such as burning of the lamp, abnormal display of a liquid crystal display panel, or screen splash.

In this regard, the backlight assembly needs an additional bezel to ensure the normal performance of the ESD test. However, the addition of the bezel also increases the thickness and weight of the backlight assembly, and is not advantageous for controlling the cost of the backlight assembly.

Disclosure of Invention

An object of the present application is to provide a backlight assembly and a display module, so as to solve the problem that a reflective film is easily burnt in an ESD test, a liquid crystal display panel displays an abnormal display or a patterned screen under a non-iron frame strip.

In order to solve the above technical problem, the present application provides a backlight assembly including: a light source and a flexible circuit board; the lamp source is arranged on the flexible circuit board. The flexible circuit board comprises a first wiring layer, a first grounding layer and a second grounding layer; the flexible circuit board is provided with a first side and a second side which are opposite, the first grounding layer and the first routing layer are both positioned on the first side of the flexible circuit board, and the first grounding layer is continuously arranged around the first routing layer; the second ground layer is located on a second side of the flexible circuit board. The first grounding layer and the second grounding layer are electrically connected with a grounding pin of the flexible circuit board. It should be appreciated that the backlight assembly can reduce the damage of static electricity to successfully pass the ESD test without using an iron frame based on the cooperation of the first ground layer and the second ground layer. And because there is no chase, can also reduce the manufacturing cost of the back light assembly, realize the light and thin of the back light assembly.

In some embodiments, the first ground plane is in a zigzag shape and is continuously disposed around the first routing layer. Therefore, the conduction effect of the first grounding layer on static electricity can be improved, and the damage of the static electricity on structures such as a lamp source, a display IC of a display panel, metal wiring and the like can be reduced.

In some embodiments, the first ground layer or the second ground layer is a metal layer in a grid shape, so as to ensure flexibility of the flexible circuit board, and facilitate bending according to a use requirement.

In some embodiments, the first ground layer or the second ground layer is a sheet-like metal layer.

In some embodiments, the metal layer is a copper layer.

In other embodiments, the metal layer may also be an ITO layer.

In some embodiments, the flexible circuit board further includes a first conductive via, and the first ground layer and the second ground layer are electrically connected through the first conductive via so as to control the overall size of the flexible circuit board 100.

In some embodiments, the flexible circuit board further includes a first conductive trace, one end of the first conductive trace is located at the first side of the flexible circuit board, and the other end of the first conductive trace is located at the second side of the flexible circuit board, and the first conductive trace is electrically connected to the first ground layer and the second ground layer. It should be appreciated that since the first ground layer, the second ground layer and the first conductive trace are located at the outer side of the flexible circuit board, the manufacture of these structures may be facilitated in some cases to improve the manufacturing yield of the flexible circuit board.

In some embodiments, the flexible circuit board further includes a reflective film for reflecting light emitted from the light source, and a heat dissipation film located on a side of the reflective film and away from the flexible circuit board. The heat dissipation film can improve the heat dissipation performance of the backlight assembly so as to reduce the possibility of generating wrinkles on the reflecting film.

In some embodiments, the heat dissipation film includes a main body portion and an extension portion, the main body portion is located on one side of the reflection film, and the extension portion extends from a side of the main body portion and extends to a side of the light source away from the flexible circuit board. It should be understood that the extension of the heat dissipation film may extend to the first side of the flexible circuit board. Based on this, the extension part can disperse the heat generated by the lamp source during the high-temperature and high-humidity environment test, so as to reduce the possibility that the reflecting film is wrinkled due to heating in the area close to the lamp source.

In some embodiments, the heat spreading film is a graphite sheet.

In some embodiments, the flexible circuit board further comprises a second routing layer located between the first routing layer and the second ground layer; the second routing layer is electrically connected with the first routing layer through a second conductive hole.

The application also provides a display module which comprises a display panel and the backlight assembly of each embodiment. The backlight assembly is used to provide a light source to the display panel.

In some embodiments, the display module is applied to an electronic device. The electronic device may include a mobile phone, a vehicle-mounted navigator, a display, a notebook computer, a tablet computer, a television, or the like.

According to the flexible circuit board, the surface of the flexible circuit board can be covered as much as possible through the first grounding layer and the second grounding layer, and the conduction efficiency of static electricity is improved. Based on this, outside canceling the iron frame required by the existing backlight assembly, static electricity can be conducted to the grounding pin of the flexible circuit board in time, so that the possibility of conducting the static electricity in the reflecting film is reduced, and the harm of the static electricity to the backlight assembly is reduced.

Drawings

Fig. 1 is a schematic view of a display module according to an embodiment of the present application.

Fig. 2 is a cross-sectional view of a flexible circuit board according to an embodiment of the present application.

Fig. 3 is a top view of a flexible circuit board of an embodiment of the present application on a first side.

Fig. 4 is a top view of a flexible circuit board on a second side according to an embodiment of the present application.

Fig. 5 is a top view of a flexible circuit board according to another embodiment of the present application.

Fig. 6 is a cross-sectional view of a flexible circuit board of another embodiment of the present application.

Fig. 7 is a schematic view of a display module according to another embodiment of the present application.

Fig. 8 is a partial top view of a flexible circuit board and heat sink of another embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.

In a passive light emitting display module, the display module comprises a display panel and a backlight assembly. The display panel cannot actively emit light, and the backlight assembly can provide a light source. Through the cooperation of the display panel and the backlight assembly, the display module can present images. The backlight assembly includes a lamp source, a flexible circuit board, and a reflective film. The lamp source can be welded on the PFC, and the flexible circuit board can be electrically connected with a main circuit board of the display module through pins. The reflective film may be positioned at a side of the lamp source and away from the display panel. The reflecting film is internally provided with a metal layer in a clamping way so as to improve the reflecting effect on the light rays emitted by the lamp source.

In which, the backlight assembly needs to be tested in ESD and high temperature and humidity environment before being shipped out of a factory to meet the relevant compliance standards. However, in the ESD test, static electricity is easily conducted through the metal layer of the reflective film based on the characteristics of the reflective film, thereby causing a certain damage to the backlight assembly. For example: the static electricity is easy to discharge through the edge of the metal layer, so that the lamp source is broken down and burnt, and the light emitted by the backlight assembly is not uniform; even, when all lamp sources are burnt out by static electricity, the backlight assembly can not provide a light source, the display panel can not be lightened, and the display module can also correspondingly generate the problem of black screen. In addition, static electricity of the ESD test may also interfere with or break down a display IC or a metal trace of the display panel, resulting in problems such as a black screen or a patterned screen of the display module.

And because the high temperature resistance of the reflective film is poor, the reflective film is easy to wrinkle in a high-temperature high-humidity environment test, and the reflection effect of the reflective film on the lamp source is reduced. Wherein the elevated temperature may be, for example, 60 ℃ and the elevated humidity may be, for example, 90% relative humidity.

It should be understood that, in order to ensure that the backlight assembly can successfully pass the above test, an iron frame is additionally provided to the backlight assembly, so that static electricity generated during the ESD test can be conducted through the iron frame and wrinkles of the reflective film can be prevented from being generated during the high temperature and high humidity environment test. However, the added bezel also increases the cost of the backlight assembly, and further increases the weight and thickness of the backlight assembly, which is not favorable for controlling the manufacturing cost of the backlight assembly, and is also not favorable for realizing the lightness and thinness of the backlight assembly and improving the integration level of the display module.

Referring to fig. 1, in view of the above problems, the present embodiment provides a display module 10 including a display panel 20 and a backlight assembly 30. It should be understood that the backlight assembly 30 smoothly passes the above-mentioned ESD and high temperature and high humidity environment test without using an iron frame. Since there is no bezel, the manufacturing cost of the backlight assembly 30 can be reduced, the backlight assembly 30 can be made thinner, and the integration level of the corresponding display module 10 can be improved.

In some embodiments, the backlight assembly 30 is disposed on one side of the display panel 20, and it should be understood that the backlight assembly 30 may be further away from the user relative to the display panel 20 during normal use of the display module 10. The display panel 20 may be, for example, a liquid crystal display panel or other panels that require an external light source; correspondingly, the backlight assembly 30 can emit light to illuminate the display panel 20, so that the user can see the corresponding picture.

In some embodiments, the display module 10 can also be applied to an electronic device as a part of the electronic device. The electronic device may include a mobile phone, a car navigator, a display, a notebook computer, a tablet computer, or a television.

Taking the display panel 20 as an example of a liquid crystal display panel, the backlight assembly is located at one side of the liquid crystal display panel, and the liquid crystal display panel 20 may include, for example, a first substrate and a second substrate, and liquid crystal is disposed between the first substrate and the second substrate. Under the power-on condition, the backlight assembly can emit light rays, and the light rays are emitted to the liquid crystal display panel after the steps of convergence, diffusion and the like. The liquid crystal of the liquid crystal display panel can correspondingly control the transmission degree of the light so as to present images.

Referring to fig. 1, a backlight assembly 30 provided in the present embodiment may include a flexible circuit board 100, a light source 210, and a reflective film 220. The flexible circuit board 100 has a pad, and the lamp source 210 may be fixed on the pad of the flexible circuit board 100 by soldering or the like, thereby achieving electrical connection between the lamp source 210 and the flexible circuit board 100. The reflective film 220 may be positioned at a side of the light source 210 and away from the display panel 20. It should be understood that the reflective film 220 may reflect light emitted from the lamp source 210 in a direction toward the display panel 20 under a power-on condition.

In some embodiments, the flexible circuit board 100 may be located directly above or obliquely above the reflective film 220, which is not limited thereto. The reflective film 220 may be, for example, a silver reflective film or esr (enhanced Specular reflector). The light source 210 may be, for example, an LED lamp or a fluorescent lamp. The number of the light sources can be one, two or more, and the number can be adjusted adaptively according to the type of the light sources.

Referring to fig. 1, in some embodiments, the backlight assembly 30 is illustrated as an edge-lit backlight assembly 30. Correspondingly, the backlight assembly 30 may further include a light guide 230, and the light guide 230 is disposed on the reflective film 220 and may be used for transmitting light emitted from the light source 210.

Referring to fig. 2, fig. 3 and fig. 4, in some embodiments, the flexible circuit board 100 has a first side 100a and a second side 100b opposite to each other, the first side 100a is a side where the light source 210 is disposed, the second side 100b is a side away from the light source 210, and an area between the first side 100a and the second side 100b is an interior of the flexible circuit board 100. The flexible circuit board 100 includes a wiring layer 110, and a pad 118 is disposed on the wiring layer 110 to facilitate electrical connection with the light source 210. In order to reduce the possibility that the lamp 210 will be broken down and burned down by static electricity during the ESD test, the flexible circuit board 100 further includes a ground layer 120 for conducting static electricity. The ground layer 120 and the routing layer 110 may be separated by an insulating medium 150 to ensure that the respective functions of the ground layer 120 and the routing layer 110 are normally achieved.

It should be understood that the ground layer 120 may be partially disposed on the first side 100a of the flexible circuit board 100, and partially disposed on the second side 100b of the flexible circuit board 100, and the two portions may be electrically connected through the first conductive via 126, so as to control the overall size of the flexible circuit board 100. Based on this, the ground layer 120 can cover the surface of the flexible circuit board 100 as much as possible and improve the efficiency of conduction of static electricity. Based on the ground layer 120, static electricity can be timely conducted to the ground pin (GNDPIN) of the flexible circuit board 100, so as to reduce the possibility of static electricity conducting in the reflective film 220 and reduce the damage of static electricity to the backlight assembly 30.

Referring to fig. 2 and fig. 3, in some embodiments, the routing layer 110 may include a first routing layer 112 and a second routing layer 114, where the first routing layer 112 is located on the first side 100a of the flexible circuit board 100, and the second routing layer 114 is located inside the flexible circuit board 100. It should be understood that first routing layer 112 and second routing layer 114 may be spaced apart by insulating medium 150, and that electrical connection between first routing layer 112 and second routing layer 114 may be made through second conductive via 116.

Referring to fig. 2, 3 and 4 simultaneously, in some embodiments, the ground plane 120 may include a first ground plane 122 and a second ground plane 124; the first ground layer 122 is disposed on the first side 100a of the flexible circuit board 100, and the second ground layer 124 is disposed on the second side 100b of the flexible circuit board 100. The first ground layer 122 and the second ground layer 124 can be electrically connected through the first conductive hole 126 to conduct static electricity to the ground pin 140 of the flexible circuit board 100. The ground pin 140 of the flexible circuit board 100 can be connected to the ground of the main circuit board of the display module 10, so as to reduce the possibility of electrostatic breakdown and burning of the lamp source 210 during the ESD test, thereby ensuring the normal operation of the backlight assembly 30.

In some embodiments, the first ground layer 122 and the first routing layer 112 may be located on the same layer, and the first ground layer 122 may be continuously disposed around the first routing layer 112. It should be understood that the first ground plane 122 may be exposed; that is, when the user picks up the flexible circuit board 100, the user's finger can directly touch the first ground layer 122. In contrast, static electricity can more easily achieve conduction through the first ground layer 122 to improve conduction efficiency.

Referring to fig. 3, in some embodiments, the first ground layer 122 is substantially "loop" shaped and is disposed continuously around the first wiring layer 112. Therefore, the effect of the first ground layer 122 on conducting static electricity can be improved, and the damage of static electricity to the lamp source 210, the display IC of the display panel 20, the metal wiring and other structures can be reduced.

Referring to fig. 5, in other embodiments, the first ground layer 122 may also be disposed continuously around the first routing layer 112, which may also achieve the function of conducting static electricity.

In some embodiments, the ground layer 120 may be a grid-shaped metal layer while satisfying the effect of conducting static electricity, so as to ensure flexibility of the flexible circuit board 100 and facilitate bending according to the use requirement. For example: the ground plane 120 in various embodiments may be a grid-like layer of copper. In other embodiments, the ground layer 120 may also be a grid-shaped ITO layer.

In other embodiments, the ground layer 120 may be a sheet-like metal layer with a large area coverage, which is not limited to this. For example: the ground layer 120 may be a sheet-like copper layer or an ITO layer, etc.

Further, from another point of view, the flexible circuit board 100 as a whole can also be understood to have a three-layer structure. The first layer structure includes a first routing layer 112 and a first ground layer 122, the first ground layer 122 being exposed and disposed about the first routing layer 112. The second layer structure includes a second routing layer 114, and the second routing layer 114 is electrically connected to the first routing layer 112 through a second conductive via 116. The third layer structure includes a second ground layer 124, and the second ground layer 124 may be electrically connected to the first ground layer 122 through the first conductive via 126. In order to conduct static electricity, the first ground layer 122 and the second ground layer 124 may be connected to the ground pin 140 of the flexible circuit board 100 and conduct static electricity.

Referring to fig. 2 again, in some embodiments, the flexible circuit board 100 may further include a protection layer 130, where the protection layer 130 is located on the first routing layer 112 and is far away from the second routing layer 114. It should be appreciated that the protective layer 130 may protect the first routing layer 112 to some extent, reduce the possibility of static electricity entering the first routing layer 112, and reduce the possibility of scratching or marking the first routing layer 112. The material of the protection layer 130 may be the same as the material of the insulating medium 150. And in the area corresponding to the pad 118, the portion of the protective layer 130 may be removed to facilitate the positioning of the light source 210.

In some embodiments, the flexible circuit board 100 may have a positive electrode pin, a negative electrode pin, and the like, in addition to the ground pin 140.

It should be understood that the first ground layer 122 and the second ground layer 124 may be electrically connected by other means besides using the first conductive hole, etc. Referring to fig. 6, the first ground layer 122 and the second ground layer 124 may be electrically connected by a first conductive trace 128. The first conductive trace 128 is disposed on a side of the flexible circuit board 100, one end of the first conductive trace 128 may be located on the first side 100a of the flexible circuit board 100, and the other end of the first conductive trace 128 may be located on the second side 100b of the flexible circuit board 100, so as to connect the first ground layer 122 and the second ground layer 124 located on different sides of the flexible circuit board 100.

It should be appreciated that since the first ground layer 122, the second ground layer 124 and the first conductive trace 128 are all located at the outer side of the flexible circuit board 100, the fabrication of the structures (122, 124, 128) may be facilitated in some cases to improve the yield of the flexible circuit board 100.

Referring to fig. 7 and 8 simultaneously, in some embodiments, in order to reduce the damage of static electricity and reduce the possibility of wrinkles generated in the reflective film 220 under the high temperature and high humidity environment test, the backlight assembly 30 may further include a heat dissipation film 240, and the heat dissipation film 240 is disposed on one side of the reflective film 220 and is far away from the flexible circuit board 100. It should be appreciated that the heat dissipation film 240 has better heat dissipation performance, thereby improving the heat dissipation performance of the backlight assembly 30. In the high temperature and high humidity environment test, the possibility of the wrinkle of the reflective film 220 can be reduced based on the heat dissipation effect of the heat dissipation film 240 on the reflective film 220.

In some embodiments, the heat dissipation film 240 has a substantially "Contraband" shape or a U-shape, that is, the heat dissipation film 240 can be bent and extended toward the flexible circuit board 100 while wrapping the reflective film 220. The heat dissipation film 240 may include a main body portion 242 and an extension portion 244, and the extension portion 244 is located at one side of the main body portion 242. The main body 242 is disposed on one side of the reflective film 220. The extension 244 extends toward the flexible circuit board 100 and is disposed around the flexible circuit board 100 and the light source 210.

It should be understood that the extension portion 244 of the heat dissipation film 240 may extend to the first side 100a of the flexible circuit board 100 and be located on the light source 210. Based on this, during the testing of the high temperature and high humidity environment, the extension 244 of the heat dissipation film 240 can dissipate the heat generated by the lamp source 210, so as to reduce the possibility that the reflection film 220 will wrinkle due to heat in the area near the lamp source 210.

In addition, since the heat dissipation film 240 can wrap the side of the reflective film 220, static electricity can be shielded to some extent during the ESD test, so as to reduce the possibility that static electricity enters the reflective film 220 from the side of the reflective film 220. Based on this, the reflective film 220 can also reduce the damage of static electricity to the backlight assembly, and reduce the possibility of static electricity breaking through the display IC or metal traces of the display panel 20.

In some embodiments, the heat dissipation film 240 may be a film structure with good heat dissipation performance, such as a graphite sheet. The heat dissipation film 240 may have a size of about one third of that of the reflection film 220.

While the foregoing is directed to embodiments of the present application, it will be appreciated by those skilled in the art that various changes and modifications may be made without departing from the principles of the application, and it is intended that such changes and modifications be covered by the scope of the application.

Claims

1. A backlight assembly, comprising: a light source and a flexible circuit board; the lamp source is arranged on the flexible circuit board;

the flexible circuit board comprises a first wiring layer, a first grounding layer and a second grounding layer; the flexible circuit board is provided with a first side and a second side which are opposite, the first grounding layer and the first routing layer are both positioned on the first side of the flexible circuit board, and the first grounding layer is continuously arranged around the first routing layer; the second grounding layer is positioned on the second side of the flexible circuit board;

the first grounding layer and the second grounding layer are electrically connected with a grounding pin of the flexible circuit board.

2. The backlight assembly of claim 1, wherein the first ground layer is in a zigzag shape and is continuously disposed around the first wiring layer.

3. The backlight assembly of claim 1 or 2, wherein the first ground layer or the second ground layer is a mesh-shaped metal layer.

4. The backlight assembly of claim 1 or 2, wherein the first ground layer or the second ground layer is a sheet-like metal layer.

5. The backlight assembly of claim 3 or 4, wherein the metal layer is a copper layer.

6. The backlight assembly of claim 1, wherein the flexible circuit board further comprises a first conductive hole, and the first ground layer and the second ground layer are electrically connected through the first conductive hole.

7. The backlight assembly of claim 1, wherein the flexible circuit board further comprises a first conductive trace, one end of the first conductive trace is located at a first side of the flexible circuit board, the other end is located at a second side of the flexible circuit board, and the first conductive trace electrically connects the first ground layer and the second ground layer.

8. The backlight assembly of any one of claims 1 to 7, wherein the flexible circuit board further comprises a reflective film for reflecting light emitted from the lamp source and a heat dissipation film on a side of the reflective film and away from the flexible circuit board.

9. The backlight assembly of claim 8, wherein the heat dissipation film comprises a main body portion at a side of the reflection film and an extension portion extending from a side of the main body portion and to a side of the light source away from the flexible circuit board.

10. The backlight assembly of claim 8, wherein the heat dissipation film is a graphite sheet.

11. The backlight assembly of claim 1, wherein the flexible circuit board further comprises a second routing layer between the first routing layer and the second ground layer; the second routing layer is electrically connected with the first routing layer through a second conductive hole.

12. A display module comprising a display panel and the backlight assembly of any one of claims 1 to 11; the backlight assembly is used for providing a light source to the display panel.

13. The display module of claim 12, wherein the display module is used in an electronic device.