Display device and motor vehicle comprising a display device

Abstract

Display device (100) comprising a backlighting unit (10), a liquid crystal display panel (11), at least one liquid crystal optics unit (12, 12a, 12b) and a control unit (16), wherein the liquid crystal optics unit (12, 12a, 12b) comprises liquid crystals (13) which change their refractive index profiles depending on applied electrical voltages (22), wherein the control unit (16) is configured to effect a dynamic change in the emission characteristics of the display device (100) by controlling the liquid crystal optics unit (12, 12a, 12b), wherein the control of the liquid crystal optics unit (12, 12a, 12b) is effected by means of software implemented in the control unit (16), characterized in that the dynamic change in the emission characteristics is configured differently in different areas (23, 24) of the liquid crystal display panel (11).wherein the change in the emission characteristic between and / or in the different areas (23, 24) is continuous, such that the emission characteristic can be changed continuously and steadily in a horizontal and in a vertical direction over an emission surface (17) of the liquid crystal display panel (11), and that the dynamic change in the emission characteristic is continuous and steady over time, such that a viewing angle can be varied differently for different observers from different directions at different times.

Description

[0001] The present invention relates to a display device comprising a backlight unit, a liquid crystal display panel, at least one liquid crystal optical unit, and a control unit. The liquid crystal optical unit comprises liquid crystals that change their refractive index profiles depending on applied electrical voltages. Furthermore, the present invention relates to a motor vehicle comprising a display device.

[0002] In modern motor vehicles, increasing emphasis is being placed on providing the driver and other passengers with a wide range of visual information. However, not every piece of information is intended for every passenger. For example, a video may be shown to a passenger on a display device. To avoid distracting the driver, it is therefore preferable to ensure that they cannot view the video image. Therefore, there is a desire for a privacy mode for display devices in the vehicle interior.

[0003] Displays with a private mode not only make it possible to show the passenger, for example, films or videos for entertainment. Vehicles that transport multiple passengers also make it possible to show the passengers content while simultaneously protecting it from being viewed by other passengers. For other information, however, it can be advantageous if it can be viewed by everyone simultaneously. It is therefore advantageous for such display devices to have a public viewing mode in addition to a private mode.

[0004] DE 10 2019 005 193 A1 discloses a filter for a passenger display that is switchable to prevent lateral views of the passenger display. The filter comprises a static and a switchable privacy screen arranged one above the other, as well as light sources assigned to each privacy screen for illuminating it.

[0005] DE 11 2010 004 660 T5 discloses a liquid crystal display device having a first backlight unit and a second backlight unit. The first backlight unit includes a first optical element that transmits light emitted from the second backlight unit, converts light emitted from a light source into light having a narrow-angle directional distribution, and radiates the converted light toward the back surface of the liquid crystal display panel. The second backlight unit includes a second optical element that converts light emitted from a light source into light having a wide-angle directional distribution and radiates the converted light toward the back surface of the liquid crystal display panel.

[0006] US 2018 / 0364405 A1 discloses a viewing angle control element comprising a biaxial compensation layer and a plurality of polarizers. The polarizers are arranged on opposite sides of the biaxial compensation layer.

[0007] US 2017 / 0336661 A1 discloses a backlighting device comprising a waveguide and a light source arrangement. The waveguide may have a stepped structure.

[0008] US 10,663,776 B1 discloses a display control unit that controls a viewing angle in a display system, wherein a private mode and a public mode can be set. The display control unit comprises a backlight unit and a lens assembly.

[0009] US 2020 / 0319512 A1 discloses a display with locally dimmable backlighting and an active privacy mode. The display may include a backlight source, lenses, a passive diffuser, an active diffuser, and a transmissive display. The backlight source may define a two-dimensional array of light sources configured to generate an output light. The lenses may be mounted adjacent to the backlight source and aligned with the light sources to produce collimated light.

[0010] US 10,649,248 B1 discloses a display with liquid crystal layers arranged between a color filter layer and a thin-film transistor layer or a layer containing organic light-emitting diodes. The display can be configured to form an array of pixels and display images. A viewing angle adjustment layer can overlap the liquid crystal layers.

[0011] In the prior art, so-called barrier or louvre films are applied in front of and / or behind a liquid crystal display panel to restrict the viewing area. Such films are used, for example, for computer or laptop monitors. However, the louvre films absorb a high proportion of the light, thus reducing the brightness of the liquid crystal display panel. Furthermore, switching between different modes is not possible.

[0012] It is also known to arrange lenses or lenticulars in front of a liquid crystal display panel, so that the liquid crystal display is only visible within a small angular range in front of the liquid crystal display panel. While this solution provides greater light output, there is no option to switch between a private and a public mode.

[0013] Another prior art solution involves the use of two different backlighting units, each assigned to a large and a small viewing area. Depending on the mode, one of the two backlighting units is switched on. However, the solution using two backlighting units requires a significant increase in complexity, as multiple LEDs and optical components are required.

[0014] The object of the present invention is to provide a display device which has variable viewing modes and can be manufactured cost-effectively with little technical effort.

[0015] To achieve the object underlying the invention, a display device comprising a backlight unit, a liquid crystal display panel, at least one liquid crystal optical unit and a control unit is proposed, wherein the liquid crystal optical unit comprises liquid crystals which change their refractive index profiles as a function of applied electrical voltages, wherein it is further provided that the control unit is designed to cause a dynamic change in a radiation characteristic of the display device by controlling the liquid crystal optical unit, that the control of the liquid crystal optical unit takes place by means of software executed in the control unit, that the dynamic change in the radiation characteristic is designed differently in different regions of the liquid crystal display panel, wherein the change in the radiation characteristic is continuous between and / or in the different regions,such that the radiation characteristic can be varied continuously and steadily in a horizontal and vertical direction across a radiation surface of the liquid crystal display panel, and that the dynamic change in the radiation characteristic is steady and continuous in time, so that a viewing angle can be varied differently for different observers from different directions at different times.

[0016] The liquid crystal optical unit contains liquid crystals, also called "liquid crystals" (LCs), which can change their refractive index depending on an applied electric field. This occurs when the liquid crystals change their orientation relative to the optical axis when the intensity of the electric field is changed. When the electric field is switched off, the liquid crystals return to their original position, allowing light to pass through the liquid crystal optical unit without refraction.

[0017] The liquid crystal display panel can, for example, be designed as a TFT liquid crystal display panel.

[0018] The backlighting unit preferably comprises a waveguide and LEDs.

[0019] According to the invention, the control unit is designed to effect a dynamic change in the radiation characteristics of the display device by controlling the liquid crystal optical unit. For this purpose, the control unit controls the electrical voltage applied to the liquid crystal optical unit.

[0020] Due to the dynamic change in the radiation characteristics, the display device has multiple viewing modes, for example, a private mode and a public mode. Furthermore, the dynamic change in the radiation characteristics makes it possible to vary the viewing modes or, for example, to create dynamically smooth transitions between the different viewing modes.

[0021] By dynamically changing the radiation characteristics, the field of view of the display device can be changed dynamically, which leads to a significant increase in the flexibility of the display device, especially in automotive applications.

[0022] Compared to solutions known from the prior art, the display device according to the invention also has only one backlight unit and preferably only one liquid crystal optical unit. Production is therefore technically much less complex and more cost-effective than with the devices known from the prior art.

[0023] It is preferably provided that the at least one liquid crystal optical unit is arranged between the backlighting unit and the liquid crystal display panel, or that the liquid crystal display panel is arranged between the backlighting unit and the at least one liquid crystal optical unit.

[0024] It is further preferably provided that the liquid crystal display panel and / or the liquid crystal optical unit are designed to be touch-sensitive.

[0025] The liquid crystal display panel and / or the liquid crystal optical unit can thus be designed as a touchscreen. It is preferably provided that the liquid crystal display panel is designed as a touch display and that the liquid crystal optical unit is arranged between the backlight unit and the liquid crystal display panel.

[0026] It is preferably provided that the dynamic change in the emission characteristic comprises a change in an emission angle of a light of the backlighting unit transmitted through the liquid crystal optical unit, wherein the change in the emission angle is preferably a focusing or a defocusing and / or a scattering of the light.

[0027] The backlighting unit is preferably a so-called “privacy backlight”, which has a reduced beam angle.

[0028] For example, the backlighting unit can have a radiation range of + / - 45° vertically and / or + / - 15° horizontally. The radiation range specified by the backlighting unit can be changed by means of the dynamic variation of the radiation characteristics enabled by the control unit and the liquid crystal optics unit. Thus, it can be provided that the radiation range of the backlighting unit can be dynamically expanded to + / - 60° horizontally by dynamically varying the radiation characteristics. Such a variation of the horizontal radiation characteristics is particularly advantageous in motor vehicles to ensure that the liquid crystal display panel can be read by all passengers.

[0029] Similarly, the vertical beam range of the backlighting unit can be dynamically expanded by dynamically changing the beam pattern. By selectively restricting the horizontal beam range of the backlighting unit, reflections in vehicle windows can be reduced, for example.

[0030] According to the invention, the dynamic change of the radiation characteristic is constant and / or continuous over time.

[0031] In other words, the transition between the individual viewing modes, for example between a private mode and a public mode, can be fluid and continuous.

[0032] Furthermore, the invention provides that the dynamic change in the radiation characteristic is designed differently in different regions of the liquid crystal display panel, wherein the change in the radiation characteristic is continuous between and / or in the different regions.

[0033] The radiation pattern is thus not only dynamic over time, but also dynamic or variable across the radiation surface of the liquid crystal display panel. Thus, a first area of ​​the radiation surface of the liquid crystal display panel can have different radiation patterns than a second area. For example, the right side of the liquid crystal display panel can be switched to a private mode, whereas the left side of the liquid crystal display panel can be switched to a public mode.

[0034] The transition of the radiation characteristics between the respective areas is intended to be smooth or continuous. In other words, the radiation characteristics change horizontally and / or vertically continuously and steadily across the radiation surface of the liquid crystal display panel. Since the change in the radiation characteristics is also smooth and continuous over time, the viewing angle can be varied differently for different observers from different directions at different times. Furthermore, optical effects can be dynamically created through the spatially and / or temporally continuous dynamic change of the radiation characteristics. For example, the field of view, i.e. the area from which information output on the radiation surface of the liquid crystal display panel is visible, can be swiveled through the room similar to a searchlight.Lens effects can be created, or optical distortion of the displayed content caused by the viewer's perspective can be compensated for.

[0035] According to the invention, the control of the liquid crystal optical unit is carried out by means of software executed in the control unit.

[0036] Preferably, the control unit is provided with the option of software updates. This makes it possible to add new viewing modes to the display device.

[0037] It is preferably provided that the liquid crystal optical unit has two substrates, preferably made of glass, wherein the liquid crystals are arranged between the two substrates.

[0038] It is further preferred that light-transmitting electrodes are arranged on the substrate to create an electric field.

[0039] It is preferably provided that the control unit is designed to effect the dynamic change in the radiation characteristic of the display device as a function of an observer position, preferably as a function of detected sensor data, and / or as a function of a display content.

[0040] To determine the observer position, sensors such as cameras can be provided which collect sensor data relating to the observer position.

[0041] For example, it can be provided that the position and orientation of the head of a vehicle occupant is determined in the motor vehicle by means of cameras and a software-based evaluation, and that the radiation characteristic of the liquid crystal display panel is dynamically changed depending on the position and orientation of the head of the vehicle occupant.

[0042] A further solution to the problem underlying the invention consists in a motor vehicle comprising a display device as described above.

[0043] The invention is explained in more detail below with reference to the accompanying figures. They show: Fig. 1 a display device comprising a backlight unit, a liquid crystal display panel and a liquid crystal optical unit, Fig. 2 a display device with a modified radiation characteristic, Fig. 3 a liquid crystal optical unit, Fig. 4a a first radiation characteristic, Fig. 4b a second radiation characteristic, Fig. 4c a third radiation characteristic, Fig. 4d a fourth radiation characteristic, Fig. 5 a display device with two liquid crystal optical units, and Fig. 6 another display device.

[0044] Fig. 1 shows a display device 100. The display device 100 comprises a backlight unit 10, a liquid crystal display panel 11, and a liquid crystal optical unit 12 arranged between the backlight unit 10 and the liquid crystal display panel 11. The liquid crystal optical unit 12 comprises liquid crystals 13 ( Fig. 3), which can change their refractive index depending on an applied electrical voltage. The backlight unit 10 comprises LEDs 14 and a light guide 15. Light 18 emitted by the backlight unit 10 strikes the liquid crystal optical unit 12. Depending on the voltage applied to the liquid crystal optical unit 12, the radiation angle of the light passing through the liquid crystal optical unit 12 is changed ( Fig. 2). The light 18 transmitted through the liquid crystal optical unit 12 then strikes the liquid crystal display panel 11, which is embodied as a touch-sensitive TFT liquid crystal display panel 11a. The voltage applied to the liquid crystal optical unit 12 is dynamically controlled by a control unit 16, so that the radiation characteristic of the display device 100, i.e., the radiation surface 17 of the liquid crystal display panel 11, is dynamically changed.

[0045] In Fig. 2 shows how the light 18 emitted by the backlight unit 10 is scattered by the dynamic change in the radiation characteristic of the display device 100, so that the viewing angle of the display device 100 is increased.

[0046] Fig. Figure 3 shows a detailed view of the liquid crystal optical unit 12. The liquid crystal optical unit 12 has two substrates 20 formed as glass panes 19, between which the liquid crystals 13 are arranged. Translucent electrodes 21 are arranged on each of the substrates 20, between which an electric field can be generated by applying a voltage 22. The liquid crystals 13 align themselves according to the applied electric field and, in the case shown, cause a scattering of the light 18 transmitted through the liquid crystal optical unit.

[0047] In the Fig. 4a to 4d schematically show different changes in the radiation characteristics of the display device 100 that can be achieved by means of the control unit 16 and the liquid crystal optics unit 12. In a first mode according to Fig. 4a, there is no voltage between the electrodes 21 of the liquid crystal optical unit 12. The light 18 passes through the liquid crystal optical unit 12 without changing the radiation angle. Fig. 4b, by applying a voltage to the electrodes 21 of the liquid crystal optical unit 12, a focusing of the light 18 passing through the liquid crystal optical unit 12 is effected. In Fig. 4c, by applying a voltage to the electrodes 21 of the liquid crystal optical unit 12, a scattering or defocusing of the light 18 passing through the liquid crystal optical unit 12 is effected. Another application is in Fig. 4d. In this case, a suitable voltage profile between the electrodes 21 causes the change in the radiation characteristic in a first region 23 to be different from that in a second region 24 of the display device 100 or of the Fig. 4d of the liquid crystal display panel 11 not shown. Thus, in the first region 23, the light 18 is deflected only slightly, whereas in the second region 24 it is strongly deflected. The transition of the radiation characteristic between the two regions 23, 24 is constant or continuous. The radiation characteristic is therefore controlled region by region. The control unit 16 is designed to change the radiation characteristic of the display device 100 continuously or steadily over time between the Fig. 4a to 4d shown cases to vary dynamically.

[0048] Fig. 5 shows a further display device 100. The display device 100 of the Fig. 5 differs from that according to Fig. 1 essentially consists in the provision of two liquid crystal optical units 12a, 12b. The first liquid crystal optical unit 12a serves to control the vertical radiation characteristic, while the second liquid crystal optical unit 12b controls the horizontal radiation characteristic.

[0049] Fig. 6 shows a further variant of the display device 100. In the display device of the Fig. 6, the order of the liquid crystal optical unit 12 and the liquid crystal display panel 11 is reversed, so that the liquid crystal display panel 11 is arranged between the liquid crystal optical unit 12 and the backlight unit 10. List of reference symbols 100 display device 10 Backlight unit 11 Liquid crystal display panel 12 Liquid crystal optics unit 12a Liquid crystal optics unit 12b Liquid crystal optics unit 13 Liquid crystal 14 LED 15 light guides 16 Control unit 17 Radiating surface 18 light 19 Glass pane 20 Substrat 21 Electrode 22 Voltage 23 First area 24 Second area

Claims

[1] A display device (100) comprising a backlight unit (10), a liquid crystal display panel (11), at least one liquid crystal optical unit (12, 12a, 12b) and a control unit (16), wherein the liquid crystal optical unit (12, 12a, 12b) comprises liquid crystals (13) which change their refractive index profiles as a function of applied electrical voltages (22), wherein the control unit (16) is designed to effect a dynamic change in a radiation characteristic of the display device (100) by controlling the liquid crystal optical unit (12, 12a, 12b), wherein the control of the liquid crystal optical unit (12, 12a, 12b) takes place by means of software executed in the control unit (16), characterized bythat the dynamic change in the radiation characteristic is designed differently in different areas (23, 24) of the liquid crystal display panel (11), wherein the change in the radiation characteristic between and / or in the different areas (23, 24) is continuous, so that the radiation characteristic can be changed continuously and continuously in a horizontal and in a vertical direction over a radiation surface (17) of the liquid crystal display panel (11), and that the dynamic change in the radiation characteristic is continuous and continuous in time, so that a viewing angle can be varied differently for different observers from different directions at different times. [2] Display device (100) according to claim 1, characterized bythat the at least one liquid crystal optical unit (12, 12a, 12b) is arranged between the backlight unit (10) and the liquid crystal display panel (11), or that the liquid crystal display panel (11) is arranged between the backlight unit (10) and the at least one liquid crystal optical unit (12, 12a, 12b). [3] Display device (100) according to claim 1 or 2, characterized by that the liquid crystal display panel (11) and / or the liquid crystal optical unit (12, 12a, 12b) is designed to be touch-sensitive. [4] Display device (100) according to one of the preceding claims, characterized by that several liquid crystal optical units (12, 12a, 12b) are provided. [5] Display device (100) according to one of the preceding claims, characterized byin that the dynamic change in the emission characteristic comprises a change in an emission angle of a light (18) of the backlighting unit (10) transmitted through the liquid crystal optical unit (12, 12a, 12b), wherein the change in the emission angle is preferably a focusing or a defocusing and / or a scattering of the light (18). [6] Display device (100) according to one of the preceding claims, characterized by that the control unit (16) is designed to effect the dynamic change of a radiation characteristic of the display device (100) as a function of an observer position, preferably as a function of detected sensor data and / or as a function of a display content. [7] Motor vehicle comprising a display device (100) according to one of claims 1 to 6.

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