Display device with cover glass

Abstract

The present invention relates to a display device (1) with a cover glass (7). The invention also relates to a means of transportation with such a display device (1). The display device (1) comprises a display panel (3), a backlight (4) for the display panel (3), and a cover glass (7). The cover glass (7) is connected to the backlight (4) by means of an adhesive (8). The adhesive (8) at least partially fills a gap (80) between the cover glass (7) and the backlight (4) and encloses an edge region (30) of the display panel (3).

Description

[0001] The present invention relates to a display device with a cover glass. The invention also relates to a means of transportation with such a display device.

[0002] The number and size of displays in vehicles are constantly increasing. Displays can be found on the market, for example, as instrument clusters for the driver, as central displays, or 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 surface, creating the most homogeneous display possible right up to the edges. Displays are typically fitted with a cover glass to protect them from damage and dirt.

[0003] For displays with a cover glass, the backlight is attached using adhesive tape or liquid adhesive. The backlight is glued either to the display panel of the display or to the cover glass, which is larger than the display panel.

[0004] For example, EP 3 125 028 A1 describes a liquid crystal display device comprising a liquid crystal display panel, a backlight unit, a cover glass, a frame, and a filler. The cover glass covers an upper surface of the liquid crystal display panel. The frame is bonded to the cover glass by the filler and surrounds the liquid crystal display panel and the backlight unit. The filler bonds the frame, the liquid crystal display panel, and the backlight unit together.

[0005] WO 2020 / 239851 A1 describes a display device comprising a display with a display surface on a front side and a rear side facing away from the display surface, and a cover plate arranged in front of the display surface. Furthermore, the display device comprises a decorative frame connected to the edge of the cover plate, which protrudes beyond the edge of the display on all sides, and a rear housing shell having a rear wall with an edge web projecting therefrom. The rear wall of the housing shell is arranged at a distance from the rear of the display, with the edge web of the housing shell being connected to the decorative frame by means of an adhesive.

[0006] When bonded to the display panel, the edges of the display panel are not protected against environmental influences or light leakage. Bonding to the cover glass can avoid this problem, but this requires a significantly wider edge. This often conflicts with the design requirements of the display device users.

[0007] It is an object of the invention to provide improved solutions for the design of a display device with a cover glass.

[0008] This object is achieved by a display device having the features of claim 1. Preferred embodiments of the invention are the subject of the dependent claims.

[0009] According to a first aspect of the invention, a display device comprises: - a display panel; - a backlight for the display panel; and - a cover glass which is bonded to the backlight; wherein the bond at least partially fills a gap between the cover glass and the backlight and encloses an edge region of the display panel.

[0010] In the inventive solution, the cover glass is bonded to the display panel and the backlight at an overlapping point. This bond seals the display panel and the backlight against environmental influences. Only a narrow edge of the cover glass is required, i.e., it allows for a reduction of the peripheral edge adjacent to the active surface of the display panel. Furthermore, the bond allows for compensation of tolerances in the step between the display panel and the cover glass. Such tolerances can be caused, for example, by lateral misalignment or uneven components.

[0011] According to one aspect of the invention, the bond is formed from a liquid adhesive. The use of liquid adhesive offers the advantage of high adhesion combined with a small wetting surface. Furthermore, tolerance compensation can be achieved particularly well with liquid adhesive. This enables stress-free installation and thus reduces errors in black image homogeneity.

[0012] According to one aspect of the invention, the bond is designed to ensure a force flow from the cover glass to the backlight. This bond ensures a mechanically stable connection, which also has a positive effect on black image homogeneity. A force flow via the display panel, on the other hand, would lead to errors in black image homogeneity.

[0013] According to one aspect of the invention, the bond is light-tight. A light-tight composition of the medium used for the bond can effectively prevent light leakage.

[0014] According to one aspect of the invention, the display panel is bonded to the cover glass by means of an optical bonding layer. The optical bonding creates a mechanically stable connection between the display panel and the cover glass. At the same time, the optical bonding layer ensures high optical quality of the image display.

[0015] According to one aspect of the invention, the backlight has a retaining element for holding optical components. Such a retaining element allows the backlight to be prefabricated with all required components and then bonded to the cover glass and the display panel as a complete module. This simplifies the manufacture of the display device. The bonding can be done directly to a backlight housing or to the retaining element.

[0016] According to one aspect of the invention, the cover glass is curved. The inventive solution is suitable for display devices of various sizes, in particular for singly or multiply curved display devices, regardless of the radius of curvature.

[0017] According to one aspect of the invention, the backlight comprises at least one planar light guide or is designed as a matrix backlight. The solution according to the invention is applicable both to backlights in which the light from one or more light sources is distributed across the surface of the display panel by means of a planar light guide, and to backlights that use a matrix of light sources for illumination, optionally in conjunction with a suitable reflector.

[0018] A display device according to the invention is preferably used in a means of transport. The means of transport can be, for example, a motor vehicle, but alternatively also an aircraft, a rail vehicle, or a watercraft. Furthermore, a display device according to the invention can also be used for display panels or in the consumer sector, e.g., for TV sets, PC monitors, smartphones, tablets, etc.

[0019] Further features of the present invention will become apparent from the following description and the appended claims taken in conjunction with the figures. Figure overview Fig. 1 schematically shows a first embodiment of a display device according to the prior art; Fig. 2 schematically shows a second embodiment of a display device according to the prior art; Fig. 3 shows a first embodiment of a display device according to the invention; Fig. 4 shows a second embodiment of a display device according to the invention; Fig. 5 shows a third embodiment of a display device according to the invention; and Fig. 6 schematically shows a means of transport that uses a display device according to the invention. Character description

[0020] 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.

[0021] Fig. 1 schematically shows a first embodiment of a display device 1 according to the prior art. It shows a section through the display device 1. The display device 1 has a display panel 3 and a backlight 4 for the display panel 3. The display panel 3 is connected to a cover glass 7 by means of an optical bonding layer 9. The backlight 4 has a housing 2 in which a planar light guide 40 and a light source arrangement 41 are located. The light source arrangement 41 has a number of light-emitting diodes 42 arranged on a circuit board 43, the light from which is coupled into the planar light guide 40. The underside of the planar light guide 40 is provided with a reflector 400 to reduce light losses through the underside.Arranged on top of the planar light guide 40 is a foil stack 401, which may include, for example, a polarizing filter and other optically effective foils. The planar light guide 40, the reflector 400, and the foil stack 401 are held by a retaining element 5, which in this embodiment is attached to the housing 2 by means of an adhesive tape 6. The cover glass 7 is connected to the backlight 4 by means of an adhesive bond 8. For this purpose, the cover glass 7 is significantly larger than the display panel 3. A force flow F from the cover glass 7 into the housing 2 of the backlight 4 occurs via the adhesive bond 8.

[0022] Fig. Figure 2 schematically shows a second embodiment of a display device 1 according to the prior art. It shows a section through the display device 1. The display device 1 largely corresponds to the display device 1 of Fig. 1. However, in this case, the cover glass 7 is not directly bonded to the backlight 4. Instead, the display panel 3 is connected to the backlight 4 by means of adhesive tape 6. The cover glass 7 can therefore have a reduced edge. However, in this case, a force flow F from the cover glass 7 into the housing 2 of the backlight 4 occurs via the display panel 3.

[0023] Fig. 3 shows a first embodiment of a display device 1 according to the invention. A section through the display device 1 is shown. The display device 1 largely corresponds to the display device 1 from Fig. 1. However, the adhesive bond 8 is designed according to the invention such that it at least partially fills a gap 80 between the cover glass 7 and the backlight 4 and encloses an edge region 30 of the display panel 3. Preferably, the adhesive bond 8 is formed from a liquid adhesive, whereby good tolerance compensation is achieved. The liquid adhesive is applied in liquid or viscous form during production and then hardens. The adhesive bond 8 ensures a direct flow of force from the cover glass 7 into the backlight 4. In the example shown, the cover glass 7 is connected to the retaining element 5. This is clamped onto the housing 2 of the backlight 4. Alternatively, the retaining element 5 can be adhesively bonded to the housing 2, as shown in Fig. 1 is the case. The bond 8 is preferably light-tight, whereby light leakage can be effectively prevented.

[0024] Fig. 4 shows a second embodiment of a display device 1 according to the invention. A section through the display device 1 is shown. The display device 1 largely corresponds to the display device 1 from Fig. 3. However, in this example, the cover glass 7 is connected to the housing 2 of the backlight 4. The retaining element 5 is attached to an inner wall of the housing 2.

[0025] Fig. Figure 5 shows a third embodiment of a display device 1 according to the invention. It shows a section through the display device 1. The display device 1 largely corresponds to the display device 1 from Fig. 3. However, in this example, the backlight 4 does not use a planar light guide to distribute the light from a light source arrangement 41 across the surface of the display panel 3. Instead, a matrix of light-emitting diodes 42 is used, which are arranged on a circuit board 43. The light-emitting diodes 42 are each arranged in cavities of a reflector 44. Between the reflector 44 and the display panel 3 is an optical plate 402 with a film stack 401 arranged thereon. The optical plate 402 is a transparent plate that ensures the optical distance between the optical film stack 401 and the light-emitting diodes 42. In the example shown, the cover glass 7 is in turn glued to the retaining element 5, which is clamped onto the housing 2 of the backlight 4. Alternatively, the retaining element 5 can also be glued to the housing 2 in this embodiment.It is also possible that the cover glass 7 is glued to the housing 2 of the backlight 4.

[0026] Fig.6 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 display device 1 is arranged in a dashboard in this example. 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 1 display device 2 housings 3 Display panel 30 Marginal area 4 Backlight 40 light guides 400 reflector 401 slide stacks 402 Optical disk 41 Light source arrangement 42 LEDs 43 circuit board 44 Reflector 5 Retaining element 6 adhesive tape 7 Cover glass 8 Bonding 80 gap 9 Optical bonding layer 100 means of transport 101 Sensor Technology 102 Navigation system 103 Data transmission unit 104 memory 105 Network F Power flow QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 3 125 028 A1

[0004] WO 2020 / 239851 A1

[0005]

Claims

[1] Display device (1) with: - a display panel (3); - a backlight (4) for the display panel (3); and - a cover glass (7) which is connected to the backlight (4) by means of an adhesive bond (8); wherein the adhesive bond (8) at least partially fills a gap (80) between the cover glass (7) and the backlight (4) and encloses an edge region (30) of the display panel (3). [2] Display device (1) according to claim 1, wherein the bond (8) is formed from a liquid adhesive. [3] Display device (1) according to claim 1 or 2, wherein the adhesive bond (8) is designed to ensure a flow of force from the cover glass (7) into the background lighting (4). [4] Display device (1) according to one of the preceding claims, wherein the adhesive bond (8) is light-tight. [5] Display device (1) according to one of the preceding claims, wherein the display panel (3) is connected to the cover glass (7) by means of an optical bonding layer (9). [6] Display device (1) according to one of the preceding claims, wherein the backlight (4) has a retaining element (5) for holding optical components (40, 400, 401, 44, 402). [7] Display device (1) according to one of the preceding claims, wherein the cover glass (7) is curved. [8] Display device (1) according to one of the preceding claims, wherein the backlight (4) has at least one planar light guide (40) or is designed as a matrix backlight. [9] Means of transport (100) with a display device (1) according to one of the preceding claims.

Images