Display device and means of transport

Abstract

The present invention relates to a display device (1) with a display panel (2) and a backlight (3) for the display panel (2). The backlight (3) comprises an arrangement (30) of light sources (31) that is smaller in at least one dimension than a corresponding dimension of the display panel (2), and an arrangement (32) of lenses (33) associated with the light sources (31). The lenses (33) are each configured to distribute the light (310) emitted by the associated light sources (31) over the entire surface of the display panel (2). The present invention also relates to a means of transportation with such a display device (1).

Description

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

[0002] The number and size of display devices in vehicles are constantly increasing. Display devices can be found, for example, as instrument clusters for the driver, central displays, and passenger displays. Non-self-illuminating transmissive displays require backlighting for image display. The purpose of the backlighting is to illuminate the display panel as uniformly as possible across its entire active area, in order to create a homogeneous display right to the edges.

[0003] Matrix backlights utilize a multitude of light sources arranged in a matrix to generate light. A reflector directs the light from these sources towards the display panel.

[0004] Head-up displays are increasingly common in vehicles. A head-up display, also known as a HUD, is a display system that allows the viewer to maintain their line of sight by projecting the displayed content into their field of vision. While such systems were initially used primarily in aviation due to their complexity and cost, they are now also being mass-produced in the automotive industry.

[0005] Head-up displays generally consist of an image-generating unit (PGU), an optical unit, and a mirror unit. The image-generating unit creates the image, using at least one display element. Most modern head-up displays use LCD-based displays (LCD: Liquid Crystal Display) for image generation. The optical unit directs the image to the mirror unit. The mirror unit is a partially reflective, translucent disc. The viewer thus sees the content displayed by the image-generating unit as a virtual image while simultaneously seeing the real world behind the disc. In automotive applications, the windshield often serves as the mirror unit, and its curved shape must be taken into account during the projection process. Through the interaction of the optical unit and the mirror unit, the virtual image is a magnified representation of the image generated by the image-generating unit.

[0006] Display lighting for head-up displays requires a highly directional beam pattern. This is typically achieved using collimators or reflector systems and multiple LEDs.

[0007] For example, EP 2 690 484 B1 describes a head-up display with a light source for emitting a beam of light, a lens arrangement for generating a multitude of images of the light source by splitting the beam of light, and a field lens for shining the beam of light emitted by the images of the light source generated by the lens arrangement onto a display element at a predetermined angle.

[0008] DE 11 2016 002 506 T5 describes a head-up display, comprising a light source unit with a light source, a converging lens facing the light source unit and focusing light, a field lens that collects the light transmitted by the converging lens and projects light at a predetermined angle, and an image-generating element that generates an image when the light arriving from the field lens is input into it and projects the light of an image towards a windshield.

[0009] The problem with existing approaches is that the homogeneity of the lighting is not optimal when only a few light sources are used. Conversely, if many light sources are installed, the costs of the overall system increase considerably.

[0010] It is an object of the invention to provide a display device that achieves homogeneous illumination with a small number of light sources.

[0011] This problem is solved by a display device having the features of claim 1 and by a means of propulsion according to claim 9. Preferred embodiments of the invention are the subject of the dependent claims.

[0012] According to a first aspect of the invention, a display device comprises a display panel and a backlight for the display panel. The backlight comprises an arrangement of light sources that is smaller in at least one direction of extension than a corresponding dimension of the display panel, and an arrangement of lenses associated with the light sources. The lenses are each configured to distribute the light emitted by the associated light sources over the entire surface of the display panel.

[0013] In the solution according to the invention, the backlight comprises an arrangement of light sources that is significantly smaller than the display panel above it, at least in one direction of extension. To nevertheless illuminate the display panel completely, the backlight also includes an arrangement of lenses that distribute the light from the light sources accordingly. In this way, a compact backlight is achieved with a reduced number of light sources and, consequently, reduced costs. The light sources can, for example, be light-emitting diodes (LEDs).

[0014] According to one aspect of the invention, the lens arrangement includes one lens for each light source. This makes it possible to optimize the lenses for the respective light source and its position relative to the display panel. In principle, however, several light sources can also be assigned to one lens, for example, 2×2 light sources from a matrix of light sources.

[0015] According to one aspect of the invention, the arrangement of light sources in both directions of expansion is smaller than the corresponding dimensions of the display panel. This allows for a further reduction in the number of light sources required and thus an additional reduction in costs.

[0016] According to one aspect of the invention, the arrangement of light sources comprises a single row of light sources. This has the advantage that only a very small number of light sources are required.

[0017] According to one aspect of the invention, the lenses each have a freeform surface designed to distribute the light emitted by the associated light sources evenly across the entire surface of the display panel. This has the advantage of providing homogeneous illumination of the display panel. Furthermore, the backlighting is stable in terms of tolerance, since all light sources distribute the light across the entire display panel.

[0018] According to one aspect of the invention, the angular distribution of the light incident on the display panel is approximated to a predetermined angular distribution. Due to the different arrangements of the light sources relative to the display panel, the illuminated light strikes the display panel at different angles. The geometry of the arrangement is therefore preferably selected such that the angular distribution is already as close as possible to the angular distribution required by the optics of the system, e.g., a head-up display. In this way, only minor further adjustments to the angular distribution are necessary.

[0019] According to one aspect of the invention, the display device comprises at least one field lens arranged on the display panel. By using one or more field lenses on the display panel, fine adjustment of the angular distribution can be achieved.

[0020] According to one aspect of the invention, the display device has at least one diffuser arranged on the display panel. Such a diffuser eliminates the discrete point characteristic of the light sources and thus ensures, for example, that continuous illumination is achieved in the eyebox of a head-up display.

[0021] Preferably, a display device according to the invention is 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. The solution according to the invention is particularly suitable for use in all display and head-up display systems that require narrow light distributions.

[0022] Further features of the present invention will become apparent from the following description and the attached claims in conjunction with the figures. Figure overview Fig. 1 schematically shows a side view of a first embodiment of a display device according to the invention along a first direction; Fig. Figure 2 schematically shows a side view of the display device. Fig. 1 along a second direction; Fig. Figure 3 schematically shows a side view of a second embodiment of a display device according to the invention along a first direction; Fig. Figure 4 schematically shows a side view of the display device. Fig. 3 along a second direction; and Fig. Figure 5 schematically shows a means of transport that uses a display device according to the invention. Character description

[0023] To better understand the principles of the present invention, embodiments of the invention are explained in more detail below with reference to the figures. The same reference numerals are used in the figures for identical or equivalently acting elements and are not necessarily described again for each figure. It is understood that the invention is not limited to the embodiments shown and that the described features can also be combined or modified without departing from the scope of protection of the invention as defined in the appended claims.

[0024] Fig. Figure 1 schematically shows a side view of a first embodiment of a display device 1 according to the invention along a first direction. Fig. Figure 2 shows a side view of the display device 1 along a second direction perpendicular to the first direction. The display device 1 comprises a display panel 2 and a backlight 3 for the display panel 2. The backlight 3 comprises an arrangement 30 of light sources 31, the extent of which is smaller in one direction than a corresponding extent of the display panel 2. Additionally, the backlight 3 comprises an arrangement 32 of lenses 33. The lenses 33 are associated with the light sources 31 and are each configured to distribute the light 310 emitted by the associated light sources 31 over the entire area of ​​the display panel 2. In the example shown, the arrangement 30 of light sources 31 consists of a single row of five light sources.

[0025] The lenses 33 are shown schematically only. In reality, each lens 33 has a freeform surface designed to distribute the light 310 emitted by the associated light sources 31 evenly over the entire surface of the display panel 2. The angular distribution of the light 311 incident on the display panel 2 is preferably already approximated to a predetermined angular distribution. At least one field lens 34 is arranged on the display panel 2 for fine-tuning the angular distribution. Additionally, a diffuser 35 is arranged on the display panel 2. This diffuser ensures that the point-like characteristics of the light sources 31 are blurred. In this way, continuous illumination can be achieved, for example, in the eyebox of a head-up display.

[0026] Fig. Figure 3 schematically shows a side view of a second embodiment of a display device 1 according to the invention along a first direction. Fig. Figure 4 shows a side view of the display device 1 along a second direction perpendicular to the first direction. The display device 1 is largely identical to the one in Fig. 1 and Fig. The display device 1 shown in Figure 2 is an example of a different embodiment. However, in this embodiment, the arrangement 30 of light sources 31 consists of a matrix of 2x4 light sources 31. The arrangement 30 of light sources 31 is smaller in both dimensions than the corresponding dimensions of the display panel 2. In this embodiment as well, each light source 31 is assigned a lens 33. It is also possible to assign one lens 33 to several light sources 31. For example, one lens 33 could be assigned to 2x2 light sources 31. In this case, the arrangement 32 of lenses 33 in the illustrated example would comprise only two lenses 33 for the total of eight light sources 31.

[0027] Fig.Figure 5 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, in the illustrated example in the form of a head-up display. Data about the vehicle's environment can be acquired by means of sensors 101. The sensors 101 can, in particular, include sensors for environmental detection, e.g., ultrasonic sensors, laser scanners, radar sensors, lidar sensors, or cameras. The information acquired by the sensors 101 can be used to generate content to be displayed on the display device 1. Further components of the motor vehicle in this example are a navigation system 102, which can provide position information, and a data transmission unit 103. The data transmission unit 103 can, for example, be used to transmit the vehicle's location to the display device 1.A connection to a backend is established, for example, to obtain updated software for vehicle components. A memory 104 is available for data storage. Data exchange between the various vehicle components takes place via a network 105. Reference symbol list 1 Display device 2 Display panels 3 Backlight 30 Arrangement of light sources 31 Light source 310 Emitted light 311 Incident light 32 Arrangement of lenses 33 lens 34 Field lens 35 Diffuser 100 means of transport 101 Sensors 102 Navigation system 103 Data transmission unit 104 storage 105 Network QUOTES INCLUDED IN THE DESCRIPTION

[0000] 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

[0000] EP 2 690 484 B1

[0007] DE 11 2016 002 506 T5

[0008]

Claims

[1] Display device (1) with a display panel (2) and a backlight (3) for the display panel (2), wherein the backlight (3) comprises: - an arrangement (30) of light sources (31) which is smaller in at least one direction of extension than a corresponding extension of the display panel (2); and - an arrangement (32) of lenses (33) associated with the light sources (31), wherein the lenses (33) are each configured to distribute the light (310) emitted by the associated light sources (31) over the entire surface of the display panel (2). [2] Display device (1) according to claim 1, wherein the arrangement (32) of lenses (33) comprises one lens (33) for each light source (31). [3] Display device (1) according to claim 1 or 2, wherein the arrangement (30) of light sources (31) in both directions of extension is smaller than a corresponding extension of the display panel (2). [4] Display device (1) according to claim 3, wherein the arrangement (30) of light sources (31) comprises a single row of light sources (31). [5] Display device (1) according to one of the preceding claims, wherein the lenses (33) each have a freeform surface designed to distribute the light (310) emitted by the associated light sources (31) uniformly over the entire surface of the display panel (2). [6] Display device (1) according to claim 5, wherein an angular distribution of the light (311) incident on the display panel (2) is approximated to a predetermined angular distribution. [7] Display device (1) according to one of the preceding claims, comprising at least one field lens (34) arranged on the display panel (2). [8] Display device (1) according to one of the preceding claims, comprising at least one diffuser (35) arranged on the display panel (2). [9] Means of transport (100) with a display device (1) according to one of the preceding claims.

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