Backlight for a display panel, display device and transport means

Abstract

The present invention relates to a backlight (3) for a display panel (2). The invention also relates to a display device having such a backlight (3) and to a transport means having such a display device. A backlight (3) according to the invention for a display panel (2) has a printed circuit board (33) with a plurality of light sources (32) arranged thereon, a film reflector (30) with a plurality of reflective cavities (31), and a carrier element (34) for the film reflector (30). At least one light source (32) is arranged in each of the cavities (31). The carrier element (34) is adapted to the shape of the film reflector (30) such that the film reflector (30) rests on the printed circuit board (33).

Description

[0001] Description

[0002] Backlight for a display panel, display device and means of transport

[0003] The present invention relates to a backlight for a display panel. The invention also relates to a display device with such a backlight and a means of transportation with such a display device.

[0004] The number and area of ​​display devices in vehicles are constantly increasing. Display devices can be found on the market, for example, as instrument clusters for the driver, as central displays, and even as passenger displays. Non-self-luminous transmissive displays require backlighting to display the image. The purpose of the backlight is to illuminate the display panel as evenly as possible across the entire active area, creating the most homogeneous display possible right up to the edges.

[0005] Matrix backlights use a multitude of light sources arranged in a matrix to generate light. A reflector directs the light from the light sources toward the display panel.

[0006] For example, DE 10 2007 007 353 A1 describes a lighting device with a luminous surface that can be assembled in a modular manner from a plurality of radiation reflectors. Honeycomb-shaped, scale-shaped, triangular, or rectangular radiation reflectors are preferably used. Each of the radiation reflectors has a plurality of radiation-reflecting surfaces that are curved outwardly from a center in which a light source is arranged. Film reflectors, in particular, can also be used as reflectors. For example, US 10,613,386 B2 describes a backlighting device with a plurality of light sources arranged in the form of a matrix and with a reflective film with partition walls. The partition walls are arranged such that they surround the light sources in four directions.

[0007] To ensure a defined position, the foil reflectors can be bonded to a lighting circuit board using an adhesive foil. The use of the adhesive foil affects the height of the reflector. The reflector is raised by the thickness of the adhesive foil. This has a negative impact on the light output, especially with side-emitting light sources.

[0008] Against this background, US 2023 / 0 012 552 A1 describes a light-emitting device comprising a substrate, a plurality of light sources arranged on the substrate, and a plurality of light-reflecting elements arranged on the substrate. The light-reflecting elements are back-injected with a resin through openings in the substrate.

[0009] However, back-injection with resin is quite labor-intensive.

[0010] It is an object of the invention to provide improved solutions for the realization of a backlight for a display panel.

[0011] This object is achieved by a background lighting system having the features of claim 1, by a display device according to claim 9, and by a means of transport according to claim 10. Preferred embodiments of the invention are the subject of the dependent claims.

[0012] According to one aspect of the invention, a backlight for a display panel comprises: - a circuit board having a plurality of light sources arranged thereon;

[0013] - a film reflector with a plurality of reflective cavities, in each of which at least one light source is arranged; and

[0014] - a support element for the foil reflector, which is adapted to the shape of the foil reflector so that the foil reflector rests on the circuit board.

[0015] With the inventive solution, the adhesive film can be eliminated by using a support element for the film reflector. The support element positions the film reflector so that it rests directly on the circuit board. The support element enables easy installation of the film reflector. Furthermore, the efficiency of the film reflector can be increased because the curvature of the film reflector's reflective surfaces can begin closer to the light sources.

[0016] According to one aspect of the invention, during the manufacture of the backlight, the carrier element is first mounted, followed by the foil reflector on the carrier element. Alternatively, the carrier element and the foil reflector can be pre-assembled. This has the advantage of reducing the number of assembly steps for the backlight assembly.

[0017] According to one aspect of the invention, the support element is made of plastic. For example, the support element can be manufactured by injection molding. The use of plastic allows for a high degree of design freedom while simultaneously keeping the support element lightweight.

[0018] According to one aspect of the invention, the support element is designed in white. This has the advantage that the reflection of the thin film of the film reflector is not impaired. According to one aspect of the invention, the support element has positioning elements. These facilitate the alignment of the support element during assembly of the backlight.

[0019] According to one aspect of the invention, the carrier element is fastened to the circuit board or a housing of the backlight. The fastening can be detachable, for example by screwing or by plugging. Locking lugs can optionally be provided for this purpose. A detachable connection has the advantage that the carrier element and the circuit board can be reused in the event of repair. Alternatively, a non-detachable fastening of the carrier element is possible, e.g., bonding using liquid adhesive or adhesive tape. Plastic deformation of fastening elements can also occur, optionally with heat input. In particular, the fastening elements can also be used as positioning elements.

[0020] According to one aspect of the invention, the carrier element rests entirely or partially on the circuit board. This ensures a very well-defined position of the carrier element relative to the circuit board or relative to the light sources.

[0021] According to one aspect of the invention, the film reflector is bonded to the carrier element. Bonding can be achieved, for example, using liquid adhesive or adhesive tape. Alternatively, the film reflector can be detachably connected to the carrier element, e.g., by plugging it in. Optional locking lugs can be provided for this purpose. A detachable connection has the advantage that the carrier element and the film reflector can be reused in the event of repair.

[0022] According to one aspect of the invention, the support element is designed in a grid-like manner. Since the light sources, and thus also the reflective cavities, are generally arranged in a grid-like manner, it is advisable to also design the support element in a grid-like manner. In particular, it can be provided that the number of webs of the support element corresponds to the number of lines in the matrix of the film reflector, i.e., all cavities of the film reflector are supported by the support element. To save weight, the webs of the support element can be partially interrupted or reduced in size.

[0023] According to one aspect of the invention, the grid structure of the support element is coarser than the grid structure of the foil reflector. This allows for weight and material savings for the support element. It is at the discretion of the person skilled in the art to determine a compromise between material savings and the support effect of the support element.

[0024] According to one aspect of the invention, the support element is designed as a single piece or multiple pieces. A single piece design simplifies handling of the support element, whereas a multiple piece design allows for assembling support elements of different sizes from basic elements.

[0025] According to one aspect of the invention, a shape of the support element is adapted to an inner contour of the film reflector. The inner contour of the film reflector can, in particular, be curved. By adapting the shape of the support element to this inner contour, deformations are avoided.

[0026] Preferably, a backlight according to the invention is used in a display device with a display panel. Such a display device is characterized by more efficient illumination, which enables higher brightness or a reduction in power consumption. Preferably, a display device according to the invention is used in a means of transportation. The means of transportation can be, for example, a motor vehicle, but alternatively also an aircraft, a rail vehicle, or a watercraft.

[0027] Further features of the present invention will become apparent from the following description and the appended claims taken in conjunction with the figures.

[0028] Figure overview

[0029] Fig. 1 shows schematically a cross section of a display device according to the prior art;

[0030] Fig. 2 shows schematically a detailed view of the backlight of the display device from Fig. 1;

[0031] Fig. 3 shows schematically the optical light alignment through the foil reflector of the backlight from Fig. 2;

[0032] Fig. 4 shows schematically a detailed view of a backlight according to the invention;

[0033] Fig. 5 shows schematically the optical light alignment through the foil reflector of the backlight from Fig. 4;

[0034] Fig. 6 shows schematically an oblique view of a foil reflector pre-assembled on a carrier element according to a first embodiment;

[0035] Fig. 7 shows a schematic oblique view of a foil reflector pre-mounted on a support element according to a second embodiment; Fig. 8 shows a schematic oblique view of a foil reflector pre-mounted on a support element according to a third embodiment; and

[0036] Fig. 9 shows schematically a means of transport that uses a display device according to the invention.

[0037] Character description

[0038] To better understand the principles of the present invention, embodiments of the invention are explained in more detail below with reference to the figures. Like reference numerals are used in the figures for like or equivalent elements and are not necessarily described again for each figure. It is understood that the invention is not limited to the illustrated embodiments and that the described features can also be combined or modified without departing from the scope of the invention as defined in the appended claims.

[0039] Fig. 1 schematically shows a cross-section of a display device 1 according to the prior art. The display device 1 has a display panel 2, which is glued to a cover glass 4. The cover glass 4 seals off a housing 8 of the display device 1 from the environment. A backlight 3 for the display panel 2 is arranged in a further housing 7. The backlight 3 has a film reflector 30 with a plurality of cavities 31. A light source 32, typically a light-emitting diode, is arranged in each of the cavities 31. The light sources 32 are arranged on a circuit board 33, which can be glued to the housing 7 of the backlight 3. The film reflector 30 is attached to the circuit board 33 by means of an adhesive film 35. In the example shown, an optical plate 5 with an optical film stack 6 arranged thereon is located between the backlight 3 and the display panel 2.The films of the optical film stack 6 are designed to scatter, collect, or direct the light from the film reflector 30 in such a way that the requirements for the solid angle of the backlight 3 are met. Typical films for light alignment are brightness enhancement films (BEF) and light control films (LCF). The optical plate 5 is a transparent plate that ensures the optical distance between the optical film stack 6 and the light sources 32. The cover glass 4, the optical plate 5, and the housing 7 of the backlight 3 are connected to one another by suitable connecting elements 9, e.g., adhesives.

[0040] Fig. 2 shows a schematic detailed view of the background lighting 3 of the display device from Fig. 1. The circuit board 33 with the light sources 32 arranged thereon and the film reflector 30 fastened to the circuit board 33 by means of the adhesive film 35 can be seen. The optical light alignment by the film reflector 30 is shown schematically in Fig. 3. In this example, the light sources 32 are laterally emitting light-emitting diodes that emit light L on all sides. As can be clearly seen, the lower light rays Lu emitted in the lower area cannot be used because they do not hit the reflective surfaces 300 of the film reflector 30.

[0041] Fig. 4 shows a schematic detailed view of a backlight 3 according to the invention. The circuit board 33 with the light sources 32 arranged thereon and the film reflector 30 are again visible. In the inventive solution, the film reflector 30 is not attached to the circuit board 33 by means of an adhesive film. Instead, a support element 34 for the film reflector 30 is installed. This is preferably made of plastic and adapted to the shape of the film reflector 30 such that the film reflector 30 rests on the circuit board 33. The film reflector 30 can be detachably or non-detachably connected to the support element 34. In the embodiment shown, the support element 34 has positioning elements 340 that engage in openings 330 in the circuit board. The support element 34 is preferably attached to the circuit board. The attachment can be detachable or non-detachable.The support element 34 is designed such that it completely or partially fills at least some of the cavities 301 of the film reflector 30. The shape of the support element 34 is preferably adapted to an inner contour of the film reflector 30.

[0042] The optical light alignment by the film reflector 30 is schematically shown in Fig. 5. The light sources 32 are again side-emitting light-emitting diodes that emit light L from all sides. As can be clearly seen in comparison with Fig. 3, a larger proportion of the lower light rays Lu emitted in the lower area strike the reflective surfaces 300 of the film reflector 30 and can therefore be used for backlighting the display panel.

[0043] Fig. 6 schematically shows an oblique view of a film reflector 30 pre-assembled on a carrier element 34 according to a first embodiment. The grid structure of the film reflector 30 is clearly visible. The carrier element 34 also has a grid structure to match this grid structure. However, this grid structure is coarser than that of the film reflector 30, i.e., in the example shown, each grid cell 341 of the carrier element 34 comprises 4x5 cavities 31 of the film reflector 30. The grid cells 341 are enclosed by a surrounding frame 342 of the carrier element 34. In the example shown, the carrier element 34 is designed as a single piece, but it can also be designed as multiple pieces. Individual positioning elements 340 of the carrier element 34 are also visible.

[0044] Fig. 7 schematically shows an oblique view of a foil reflector 30 pre-assembled on a support element 34 according to a second embodiment. Here, too, the support element 34 has a grid structure that is coarser than the grid structure of the foil reflector 30. However, the size of the grid cells 341 of the support element 34 varies.

[0045] Fig. 8 schematically shows an oblique view of a foil reflector 30 pre-assembled on a support element 34 according to a third embodiment. This embodiment largely corresponds to that of Fig. 6, i.e., the grid cells 341 are of a uniform size. However, the webs 343 of the support element 34 have recesses 344. These allow for weight and material savings without unduly compromising the stability and support effect of the support element 34.

[0046] Fig. 9 schematically shows a means of transport 100 that uses a display device 1 according to the invention. In this example, the means of transport 100 is a motor vehicle. The motor vehicle has a display device 1 according to the invention, which is arranged in a dashboard. Data on the vehicle's surroundings can be acquired using a sensor system 101. The sensor system 101 can, in particular, comprise sensors for environmental detection, e.g., ultrasonic sensors, laser scanners, radar sensors, lidar sensors, or cameras. The information acquired by the sensor system 101 can be used to generate content to be displayed for the display device 1. Further components of the motor vehicle in this example are a navigation system 102, by means of which position information can be provided, and a data transmission unit 103. By means of the data transmission unit 103, for example,A connection to a backend can be established, for example, to obtain updated software for components of the motor vehicle. A memory 104 is provided for storing data. Data exchange between the various components of the motor vehicle takes place via a network 105. List of reference symbols.

[0047] 1 display device

[0048] 2 display panel

[0049] 3 Backlight

[0050] 30 foil reflector

[0051] 300 Reflective surface

[0052] 301 Cavity

[0053] 31 Cavity

[0054] 32 light source

[0055] 33 circuit board

[0056] 330 Opening

[0057] 34 support element

[0058] 340 Positioning element

[0059] 341 grid cell

[0060] 342 frames

[0061] 343 jetty

[0062] 344 recess

[0063] 4 Cover glass

[0064] 5 Optical disk

[0065] 6 stacks of slides

[0066] 7 Backlight housing

[0067] 8 Housing of the display device

[0068] 9 Connecting element

[0069] 100 means of transport

[0070] 101 Sensor Technology

[0071] 102 Navigation system

[0072] 103 Data transmission unit

[0073] 104 memory

[0074] 105 Network

[0075] L Light Lu Lower light beam

Claims

Patent claims 1 . Backlight (3) for a display panel (2), with: - a circuit board (33) with a plurality of light sources (32) arranged thereon; - a film reflector (30) with a plurality of reflective cavities (31), in each of which at least one light source (32) is arranged; and - a carrier element (34) for the film reflector (30), which is adapted to the shape of the film reflector (30) such that the film reflector (30) rests on the circuit board (33).

2. Backlight (3) according to claim 1, wherein the carrier element (34) is attached to the circuit board (33) or a housing (7) of the backlight (3).

3. Backlight (3) according to claim 2, wherein the carrier element (34) rests wholly or partially on the circuit board (33).

4. Backlight (3) according to one of the preceding claims, wherein the film reflector (30) is glued to the carrier element (34) or is detachably connected to the carrier element (34).

5. Backlight (3) according to one of the preceding claims, wherein the carrier element (34) is designed in the shape of a grid.

6. Backlight (3) according to claim 5, wherein a grid structure of the carrier element (34) is coarser than a grid structure of the film reflector 7. Backlight (3) according to one of the preceding claims, wherein the carrier element (34) is designed in one part or in several parts.

8. Backlight (3) according to one of the preceding claims, wherein a shape of the carrier element (34) is adapted to an inner contour of the film reflector (30).

9. Display device (1) with a display panel (2), wherein the display device (1) has a backlight (3) according to one of the preceding claims.

10. Means of transport (100) with a display device (1) according to claim 9.

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