Display device with a light guide layer and method for its operation

Abstract

Display device (10, 20) with a plurality of pixels (11) each configured to generate light (16) and a light guide layer (13) arranged and configured to receive and direct the light (16) generated by the pixels (11) in such a way as to concentrate it onto a display area (14) that is smaller than the light emission area (12) formed by the totality of the pixels (11) for viewing display content by a user (17); and method for operating such a display device (10, 20).

Description

The invention relates to a display device in which light generated by pixels is guided through an optical structure, i.e., a light guide layer. The invention further relates to a method for operating such a display device. A display device is designed to visually present content to a user. Such a display device can be designed and named as a display, monitor, flat screen, or similar device. Display devices are known from the prior art in which fiber layers serve to deflect or distribute the light generated by pixels. For example, US patent 8,976,324 B2 describes a display with two superimposed layers of optical fibers. A first fiber layer with a first numerical aperture receives the light generated by pixels and transmits it to a second fiber layer, which has a larger numerical aperture. The second fiber layer includes partially inclined fibers that fan the light outwards to allow it to overlap the display edges and thus enable a borderless display. From DE 10 2017 207 041 B4 a display system of a vehicle is further known which has a display device, a holographic light guide module and a cover plate, wherein the light guide module projects the light of a display field onto a line defined outside a display frame, so that the display frame is optically hidden and a display content is seemingly enlarged. US 9 709 783 B2 discloses a display device comprising a housing with a screen and a surrounding frame, wherein an optical element with prismatic projections mounted thereon refracts the light emanating from the edge of the screen and deflects it selectively forward, so that the frame is optically concealed. Against this background, the invention aims to provide a display device with a space-saving display area that enables high-resolution, bright, and energy-efficient display of content. Furthermore, a method for operating a display device of the type according to the invention is to be specified. This problem is solved by a display device having the features of claim 1 and by an operating method having the features of claim 10. Further particularly advantageous embodiments of the invention are disclosed in the respective dependent claims. It should be noted that the features listed individually in the claims can be combined with one another in any technically meaningful way (possibly even across category boundaries, for example between method and apparatus) and demonstrate further embodiments of the invention. The description further characterizes and specifies the invention, particularly in conjunction with the figures. It should also be noted that the conjunction “and / or” used herein, which stands between two features and links them together, is always to be interpreted in such a way that in a first embodiment of the object according to the invention only the first feature may be present, in a second embodiment only the second feature may be present, and in a third embodiment both the first and the second feature may be present. The use of the term "approximately" herein is intended to include a tolerance range that a person skilled in the art in this field would consider customary. In particular, the term "approximately" is to be understood as a tolerance range of the relative quantity of a maximum of + / -20%, preferably a maximum of + / -10%. The invention relates to a display device comprising a plurality of image points (hereinafter also referred to as pixels) and a light guide layer. The image points are each designed to generate light. The light guide layer is arranged and configured to receive the light generated by the image points and to direct it in such a way that it is concentrated onto a display area that is smaller than the light emission area formed by the entirety of the image points, for the purpose of viewing the displayed content by a user. The display area of ​​the display device is understood to be the area in which the user can clearly and sharply see the display content generated and displayed by the display device. For the purposes of this invention, a "plurality of pixels" generally means that several light-emitting elements (pixels) are present, which generate an image. These pixels can be arranged in any geometric configuration. Preferably, however, the pixels are arranged in the form of a pixel matrix, i.e., in a regular grid structure of rows and columns, as is common in conventional flat panel displays (e.g., LCD, OLED, µLED, or MicroLED). However, the reference to a "plurality of pixels" also permits embodiments in which the pixels are arranged in irregular patterns or alternative configurations. Concentrating the light generated by the pixels onto the display area, which is smaller than the total active pixel area (i.e., the light-emitting area), results in a higher perceived pixel density (i.e., resolution) and a brighter display. The display area itself requires less space. Alternatively, the higher perceived resolution on the display area can be used to manufacture displays with larger pixels, thereby reducing the display's energy consumption and manufacturing costs. Furthermore, the light concentration and the associated increased brightness on the display area can be used to operate the pixels at a lower luminance (i.e., light output), enabling the creation of an energy-efficient display without compromising the display quality of the content. In a first advantageous embodiment, the optical fiber layer is arranged directly adjacent to the plane of the pixels, i.e., the light-emitting surface. In alternative embodiments, an intermediate layer is provided between the light-emitting surface and the optical fiber layer, which selectively couples or introduces the light generated by the pixels into the optical fiber layer. This intermediate layer can be configured as a microlens array and / or have prism structures that couple the light into the optical fiber layer at a predetermined angle, and / or be configured as a refractive index matching layer and / or as a diffractive or holographic structure. In this way, the light coupling efficiency can be further increased. In further preferred embodiments, there is only a single light guide layer between the light emission surface and the display surface, which simplifies the design and makes it more cost-effective. A particularly advantageous design is that of a light guide bundle with several directed light channels concentrated on the smaller display area. The light channels can be made of glass or plastic and / or be designed as mirrored hollow channels, for example similar to a kaleidoscope. A diffuser layer can be applied to the display surface to selectively adjust a viewing angle range. The invention further relates to a method for operating a display device, in particular a display device according to one of the embodiments disclosed herein. The method comprises the steps of: - generating light by a plurality of pixels, - receiving the generated light by a light guide layer, and - guiding the received light through the light guide layer onto a display area that is smaller than the light emission area formed by the entirety of the pixels, for viewing display content by a user. It is understood that, with regard to process-related definitions as well as the effects and advantages of process-related features, full reference can be made to the disclosure of analogous definitions, effects, and advantages of the display device according to the invention, and vice versa. A repetition of explanations of analogous features, their effects, and advantages can therefore be omitted in favor of a more concise description, without such omissions being to be interpreted as a limitation of any of the disclosed subject matter of the invention. In preferred embodiments, the method additionally comprises the step of selectively coupling the light generated by the pixels into the optical fiber layer via an intermediate layer. This intermediate layer can be designed, in particular, as a microlens array, a prism structure, a refractive index matching layer, or a diffractive or holographic structure. Furthermore, the method can provide that the light guide layer is designed as a light guide bundle with a multitude of directed light channels that concentrate the light onto the display surface. Finally, a diffuser layer can be used on the display surface to selectively adjust the viewing angle range. Further features and advantages of the invention will become apparent from the following description of exemplary embodiments of the invention, which are not to be understood as limiting and are explained in more detail below with reference to the drawing. In this drawing, Fig. 1 schematically shows a cross-sectional view of a display device according to a first embodiment of the invention, and Fig. 2 shows a cross-sectional view of a display device according to a second embodiment of the invention. The specific examples described below are purely illustrative in nature and serve to clarify the basic structures and processes. Fig. 1 schematically depicts a cross-sectional view of a display device 10 according to the invention, which has a plurality of pixels 11 arranged in this case as a pixel matrix, although the arrangement of the pixels 11 is not necessarily limited to a matrix-like arrangement. Such a pixel matrix can be advantageously provided in display devices that are designed, for example, as LCD, OLED, or µLED or MicroLED display devices. The display device 10 further comprises a light guide layer 13 adjacent to the pixel matrix or the image points 11, i.e., to a light emission surface 12 formed by the entirety of the image points 11, as well as a display surface 14, which in this example is covered with a diffuser layer 15. The display device 10 is not necessarily limited to providing the diffuser layer 15. However, in Fig. 1, it at least represents the lateral extent of the display surface 14. A lateral extent of the light emission surface 12 is indicated in Fig. 1 for clarity by a wider line in the transition area from the image points 11 to the light guide layer 13. A comparison of the lateral extent of the light-emitting surface 12 with the lateral extent of the display area 14 makes it clear that the display area 14 is significantly smaller than the light-emitting surface 12 formed by all the image points 11 or pixels. In other words, the light guide layer 13 concentrates the light 16 generated by the image points 11 and coupled into the light guide layer 13 by the light-emitting surface 12 (which is shown in Fig. 1 by way of example at only one image point 11) onto the smaller display area 14, on which a user 17 views the display content generated by the display device 10. In the display area 14, the user 17 perceives the display content with a higher resolution than in the light-emitting surface 12. Furthermore, the brightness (i.e., surface brightness) of the displayed content is higher in the display area 14 than in the light-emitting surface 12. As further shown in Fig. 1, the optical fiber layer 13 in the present example is designed as an optical fiber bundle with several directed light channels 18. These are concentrated on the smaller display area 14. The light channels 18 can be made of glass or plastic and / or be designed as mirrored hollow channels, e.g., in the manner of a kaleidoscope, as is indicated by the light 16 being reflected multiple times within one of the light channels 18 in Fig. 1. The display device 10 has a housing 19 in which the pixels 11, the light guide layer 13 and, if applicable, the diffuser layer 15 are accommodated. In the display device 10 shown in Fig. 1, the light guide layer 13 is arranged directly adjacent to the light emission surface 12. Fig. 2 schematically shows a cross-sectional view of a display device 20 according to a second embodiment of the invention, in which, in contrast to the display device 10 from Fig. 1, an intermediate layer 21 is provided between the light emission surface 12 and the light guide layer 13, which is designed to selectively introduce or couple the light 16 generated by the pixels 11 into the light guide layer 13. This intermediate layer 21 can be designed as a microlens array and / or have prism structures that couple the light 16 into the optical fiber layer 13 at a predetermined angle, and / or be designed as a refractive index matching layer and / or as a diffractive or holographic structure to increase the light coupling efficiency of the light 16 from the pixels 11 into the optical fiber layer 13. REFERENCE MARK LIST: 10 Display device 11 Pixel 12 Light emission surface 13 Light guide layer 14 Display surface 15 Diffuser layer 16 Generated light 17 User 18 Light channel 19 Housing 20 Display device 21 Intermediate layer QUOTES INCLUDED IN THE DESCRIPTION This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature US 8 976 324 B2

[0004] DE 10 2017 207 041 B4

[0005] US 9 709 783 B2

[0006]

Claims

Display device (10, 20) with a plurality of pixels (11) each designed to generate light (16) and a light guide layer (13) arranged and designed to receive and direct the light (16) generated by the pixels (11) in such a way that it is concentrated onto a display area (14) that is smaller than the light emission area (12) formed by the totality of the pixels (11) for viewing display content by a user (17). Display device according to claim 1, in which the light guide layer (13) is arranged directly adjacent to the light emission surface (12). Display device according to claim 1, in which an intermediate layer (21) is provided between the light emission surface (12) and the light guide layer (13), which is designed to selectively introduce the light (16) generated by the pixels (11) into the light guide layer (13). Display device according to claim 3, wherein the intermediate layer (21) is configured as a microlens array or has prism structures that couple the light into the optical fiber layer (13) at a predetermined angle. Display device according to claim 3, wherein the intermediate layer (21) comprises a refractive index matching layer. Display device according to claim 3, wherein the intermediate layer (21) has diffractive or holographic structures. Display device according to one of the preceding claims, in which only a single light guide layer (13) is provided between the light emission surface (12) and the display surface (14). Display device according to one of the preceding claims, wherein the light guide layer (13) is designed as a light guide bundle with several directed light channels (18). Display device according to claim 8, wherein the light channels (18) are designed as mirrored hollow channels. Method for operating a display device (10, 20) comprising the steps:- generating light (16) by a plurality of pixels (11),-receiving the generated light (16) by a light guide layer (13) and-guiding the received light (16) by the light guide layer (13) onto a display area (14) smaller than a light emission area (12) formed by the totality of the pixels (11) for viewing display content by a user (17).

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