Display devices and motor vehicles including display devices

Abstract

In order to provide a display device with variable viewing modes and that can be manufactured inexpensively with less technical cost, it is proposed in a display device (100) that a control unit (16) is designed to cause dynamic changes in the radiation characteristics of the display device (100) by manipulating liquid crystal optical units (12, 12a, 12b). The display device includes 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) includes liquid crystal (13) that changes its refractive index profile according to an applied voltage (22).

Description

[0001] This 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, wherein the liquid crystal optical unit comprises liquid crystal that changes its refractive index profile according to an applied voltage. Furthermore, this invention relates to a motor vehicle including a display device.

[0002] In modern motor vehicles, there is an increasing emphasis on providing drivers and other vehicle occupants with multiple visual information displays. However, not every piece of information is intended for every occupant. For example, a video might be displayed to the front passenger on a monitor. To avoid distracting the driver, it is preferable to ensure that the driver cannot view the video image. Therefore, a privacy mode is desired for displays within the vehicle's interior.

[0003] A display device with a private mode can not only be used to show movies or videos to the front passenger for entertainment, but also to display content to passengers in multi-person vehicles while preventing other passengers from seeing it. Conversely, for other information, it can be advantageous to allow it to be seen by everyone simultaneously. Therefore, it is advantageous for the corresponding display device to have a public viewing mode in addition to a private mode.

[0004] A filter for a passenger-side display is known from patent document DE 10 2019 005 193 A1. This filter is designed to be switchable to prevent viewing of the passenger-side display from the side. The filter includes a static privacy film and a switchable privacy film arranged overlapping each other. The filter also includes a light source associated with each privacy film to illuminate it.

[0005] Patent document 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 incident from the second backlight unit, converts light output from a light source into light with a narrow angular distribution, and radiates the converted light toward the back of the liquid crystal display panel. The second backlight unit includes a second optical element that converts light output from a light source into light with a wide angular distribution and radiates the converted light toward the back of the liquid crystal display panel.

[0006] Patent document 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] A backlight device comprising a waveguide and a light source arrangement structure is known from patent document US 2017 / 0336661 A1. The waveguide may have a hierarchical structure.

[0008] Patent document US 10,663,776B1 discloses a display control unit for controlling the viewing angle in a display system, wherein a private mode and a public mode can be set. The display control unit includes a backlight unit and a lens assembly.

[0009] In existing technology, so-called privacy films or venetian blind films are installed in front of and / or behind liquid crystal display panels to limit the viewing area. Such films are used, for example, in computer or laptop monitors. However, venetian blind films absorb a higher proportion of light, thus reducing the brightness of the liquid crystal display panel. Furthermore, switching between different modes is not possible.

[0010] Furthermore, it is known that placing a lens or biconvex lens in front of the liquid crystal display panel ensures that the display is visible only within a small angle range in front of the panel. While this solution provides a larger light output, it lacks the possibility of switching between private and public modes.

[0011] Another solution known from existing technology is to use two different backlight units, one for a larger viewing area and the other for a smaller viewing area. Depending on the mode, one of these two backlight units is turned on. However, using a solution with two backlight units implies significant additional overhead, as multiple LEDs and optical components must be used.

[0012] The technical problem to be solved by the present invention is to provide a display device that has a variable viewing mode and can be manufactured inexpensively with low technical cost.

[0013] To address this technical problem, a display device is proposed, 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 crystal that changes its refractive index profile according to an applied voltage. The control unit is further specified to dynamically change the radiation characteristics of the display device by manipulating the liquid crystal optical unit.

[0014] The liquid crystal optical unit comprises a liquid crystal, also known as a "liquid crystal" or LC, which can change its refractive index profile according to an applied electric field. This is achieved by changing the orientation of the liquid crystal relative to the optical axis when the electric field strength is changed. When the electric field is turned off, the liquid crystal reorients itself to its original position, in which light can pass through the liquid crystal optical unit without refraction.

[0015] The liquid crystal display panel can be designed as a TFT liquid crystal display panel, for example.

[0016] The backlight unit preferably includes a waveguide and an LED.

[0017] According to the present invention, the control unit is designed to cause dynamic changes in the radiation characteristics of the display device by manipulating the liquid crystal optical unit. To this end, the control unit controls the voltage applied to the liquid crystal optical unit.

[0018] Due to the dynamic changes in radiation characteristics, display devices offer multiple viewing modes, such as private and public modes. Furthermore, the dynamic changes in radiation characteristics enable the variable design of viewing modes, or, for example, the dynamic and smooth design of transitions between different viewing modes.

[0019] The viewing range of a display device can be dynamically changed by dynamically altering its radiation characteristics, which greatly improves the flexibility of the display device, especially in automotive applications.

[0020] Furthermore, compared to solutions known from the prior art, the display device according to the present invention has only one backlight unit, and preferably only one liquid crystal optical unit. Therefore, compared to devices known from the prior art, the manufacturing process is significantly less technically demanding and the manufacturing cost is lower.

[0021] Preferably, the at least one liquid crystal optical unit is arranged between the backlight unit and the liquid crystal display panel, or the liquid crystal display panel is arranged between the backlight unit and the at least one liquid crystal optical unit.

[0022] In addition, it is preferred that the liquid crystal display panel and / or liquid crystal optical unit be designed to be touch-sensitive.

[0023] Therefore, the liquid crystal display panel and / or liquid crystal optical unit can be designed as a touch screen. Preferably, the liquid crystal display panel is designed as a touch display, and the liquid crystal optical unit is arranged between the backlight unit and the liquid crystal display panel.

[0024] Preferably, the dynamic changes in radiation characteristics include changes in the radiation angle of light transmitted through the liquid crystal optical unit by the backlight unit, wherein the changes in the radiation angle are preferably the focusing or defocusing and / or scattering of light.

[0025] Preferably, the backlight unit is a so-called "privacy backlight" which has a reduced radiation angle.

[0026] For example, the backlight unit can have a vertical radiation range of + / -45° and / or a horizontal radiation range of + / -15°. The preset radiation range of the backlight unit can be changed by dynamically altering the radiation characteristics implemented by the control unit and the liquid crystal optical unit. Therefore, it can be specified that the horizontal radiation range of the backlight unit can be dynamically extended to + / -60° by dynamically changing the radiation characteristics. Such alteration of the horizontal radiation characteristics is particularly advantageous in motor vehicles to ensure that all occupants can read the liquid crystal display panel.

[0027] Similarly, the vertical radiation range of the backlight unit can be dynamically expanded by dynamically changing its radiation characteristics. For example, reflections from vehicle windows can be reduced by selectively limiting the horizontal radiation range of the backlight unit.

[0028] Furthermore, it is advantageous to stipulate that the dynamic changes in radiation characteristics are stable and / or continuous in time.

[0029] In other words, the transition between individual viewing modes, such as between private and public modes, can be smooth and continuous.

[0030] It is further advantageous to specify that the dynamic changes in radiation characteristics are designed differently in different areas of the liquid crystal display panel, wherein preferably, the changes in radiation characteristics between and / or in different areas are stable.

[0031] Therefore, the radiation characteristics are not only dynamic over time, but also dynamic or variable on the radiating surface of the liquid crystal display panel. Consequently, the first region of the radiating surface of the liquid crystal display panel can have different radiation characteristics than the second region. For example, the right side of the liquid crystal display panel can switch to a private mode, while the left side switches to a public mode.

[0032] Particularly preferably, the transition of radiation characteristics between different regions is stable or continuous. In other words, the horizontal and / or vertical radiation characteristics change continuously and stably on the radiating surface of the liquid crystal display panel. Furthermore, since the change in radiation characteristics is preferably also stable and continuous in time, the viewing angle can be changed differently at different times for an observer looking from different directions. Moreover, the continuous dynamic change of radiation characteristics in space and / or time can dynamically produce optical effects. For example, the visible range, i.e., the range from which information output on the radiating surface of the liquid crystal display panel can be seen, can be swung across space like a searchlight. Lens effects can be produced, or optical distortion of the displayed content caused to the viewer due to the viewing angle can be compensated.

[0033] It is further advantageous to specify that the control of the liquid crystal optical unit is performed by software executed in the control unit.

[0034] Preferably, the software of the control unit is provided as an option. This allows new viewing modes to be added to the display device.

[0035] Preferably, the liquid crystal optical unit has two substrates, preferably made of glass, wherein liquid crystal is disposed between the two substrates.

[0036] In addition, it is preferred that the light-transmitting electrodes are arranged on the substrate in order to establish an electric field.

[0037] Preferably, the control unit is designed to cause dynamic changes in the radiation characteristics of the display device based on the observer's position, preferably based on detected sensor data, and / or based on the displayed content.

[0038] To determine the observer's position, a sensor, such as a camera, can be provided, which detects sensor data related to the observer's position.

[0039] For example, it can be stipulated that the position and orientation of the vehicle occupant's head are determined by a camera and software-based analysis in the motor vehicle, and the radiation characteristics of the liquid crystal display panel are dynamically changed according to the position and orientation of the vehicle occupant's head.

[0040] Another solution to the aforementioned technical problem lies in a motor vehicle that includes the aforementioned display device.

[0041] The invention is described in detail below with reference to the accompanying drawings. In the drawings:

[0042] Figure 1 A display device is shown, which includes a backlight unit, a liquid crystal display panel, and a liquid crystal optical unit;

[0043] Figure 2 A display device with altered radiation characteristics is shown;

[0044] Figure 3 The liquid crystal optical unit is shown;

[0045] Figure 4a The first radiation characteristic is shown;

[0046] Figure 4b The second radiation characteristic is shown;

[0047] Figure 4c The third radiation characteristic is shown;

[0048] Figure 4d The fourth radiation characteristic is shown;

[0049] Figure 5 A display device with two liquid crystal optical units is shown; and

[0050] Figure 6 This shows another display device.

[0051] Figure 1 A display device 100 is shown. The display device 100 includes a backlight unit 10, a liquid crystal display panel 11, and a liquid crystal optical unit 12 disposed between the backlight unit 10 and the liquid crystal display panel 11. The liquid crystal optical unit 12 includes liquid crystal 13 (…). Figure 3 These liquid crystals can change their refractive index profiles according to the applied voltage. The backlight unit 10 includes an LED 14 and a light guide 15. Light 18 radiated from the backlight unit 10 is incident on the liquid crystal optical unit 12. The radiation angle of the light passing through the liquid crystal optical unit 12 is changed according to the voltage applied to it. Figure 2 Subsequently, light 18 transmitted through the liquid crystal optical unit 12 is incident on the liquid crystal display panel 11, which is designed as a touch-sensitive TFT liquid crystal display panel 11a. The voltage applied to the liquid crystal optical unit 12 is dynamically controlled by the control unit 16, thus dynamically changing the radiation characteristics of the radiating surface 17 of the display device 100, i.e., the liquid crystal display panel 11.

[0052] exist Figure 2 The diagram illustrates how to scatter the light 18 emitted from the backlight unit 10 by dynamically changing the radiation characteristics of the display device 100 in order to expand the viewing angle of the display device 100.

[0053] Figure 3 A detailed view of the liquid crystal optical unit 12 is shown. The liquid crystal optical unit 12 has two substrates 20 designed as glass plates 19, with liquid crystal 13 disposed between the two substrates. Transparent electrodes 21 are disposed on each substrate 20, and an electric field can be generated between the electrodes by applying a voltage 22. The liquid crystal 13 is oriented according to the applied electric field and, in the case shown, causes scattering of light 18 transmitted through the liquid crystal optical unit.

[0054] exist Figures 4a to 4d The diagram schematically illustrates the different variations in the radiation characteristics of the display device 100 that can be achieved through the control unit 16 and the liquid crystal optical unit 12. According to... Figure 4a In the first mode, no voltage is applied between the electrodes 21 of the liquid crystal optical unit 12. Light 18 passes through the liquid crystal optical unit 12 without changing the radiation angle. Figure 4b In this process, applying a voltage to the electrodes 21 of the liquid crystal optical unit 12 causes the light 18 passing through the liquid crystal optical unit 12 to be focused. Figure 4c In this process, applying a voltage to the electrodes 21 of the liquid crystal optical unit 12 causes scattering or defocusing of the light 18 passing through the liquid crystal optical unit 12. Figure 4d Another application scenario is illustrated below. In this case, a suitable change curve of the voltage between electrodes 21 causes a change in radiation characteristics in the display device 100 or... Figure 4dThe first region 23 of the liquid crystal display panel 11 (not shown) differs from the second region 24. Therefore, light 18 is deflected less in the first region 23 and more strongly in the second region 24. The transition of radiation characteristics between these two regions 23 and 24 is stable or continuous. Therefore, the radiation characteristics are controlled regionally. The control unit 16 is designed to stably or continuously adjust the radiation characteristics over time. Figures 4a to 4d The radiation characteristics of the display device 100 are dynamically changed between the situations shown.

[0055] Figure 5 Another display device 100 is shown. Figure 5 The display device 100 and according to Figure 1 The main difference in the display device is that it has two liquid crystal optical units 12a and 12b. The first liquid crystal optical unit 12a is used to control the vertical radiation characteristics, while the second liquid crystal optical unit 12b is used to control the horizontal radiation characteristics.

[0056] Figure 6 Another variation of the display device 100 is shown. Figure 6 In the display device, the order of the liquid crystal optical unit 12 and the liquid crystal display panel 11 is interchanged, so the liquid crystal display panel 11 is arranged between the liquid crystal optical unit 12 and the backlight unit 10.

[0057] List of reference numerals

[0058] 100 display devices

[0059] 10 backlight units

[0060] 11 LCD display panel

[0061] 12 liquid crystal optical units

[0062] 12a Liquid Crystal Optical Unit

[0063] 12b Liquid Crystal Optical Unit

[0064] 13 LCD

[0065] 14 LED

[0066] 15 optical guides

[0067] 16 control units

[0068] 17 radiating surfaces

[0069] 18 light

[0070] 19 glass plates

[0071] 20 substrates

[0072] 21 electrodes

[0073] 22 voltage

[0074] 23 First District

[0075] 24 Second District

Claims

1. A display device (100), the 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 units (12, 12a, 12b) include liquid crystal (13), which changes its refractive index curve according to the applied voltage (22). The control unit (16) is designed to cause dynamic changes in the radiation characteristics of the display device (100) by manipulating the liquid crystal optical units (12, 12a, 12b). The manipulation of the liquid crystal optical units (12, 12a, 12b) is performed by software executed in the control unit (16). The dynamic changes in radiation characteristics are designed differently in different regions (23, 24) of the liquid crystal display panel (11). The changes in radiation characteristics between and / or within the different regions (23, 24) are stable, allowing the horizontal and vertical radiation characteristics to change continuously and stably on the radiation surface of the liquid crystal display panel. Furthermore, the dynamic changes in radiation characteristics are stable and continuous in time, allowing the viewing angle to be changed differently at different times for different observers viewing from different directions.

2. The display device (100) according to claim 1, characterized in that, 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 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. The display device (100) according to claim 1 or 2, characterized in that, The liquid crystal display panel (11) and / or the liquid crystal optical unit (12, 12a, 12b) are designed to be touch-sensitive.

4. The display device (100) according to claim 1, characterized in that, It is equipped with multiple liquid crystal optical units (12, 12a, 12b).

5. The display device (100) according to claim 1, characterized in that, The dynamic changes in radiation characteristics include the changes in the radiation angle of the light (18) transmitted through the liquid crystal optical units (12, 12a, 12b) of the backlight unit (10).

6. The display device (100) according to claim 5, characterized in that, The change in the radiation angle is the focusing of the light (18).

7. The display device (100) according to claim 5, characterized in that, The change in the radiation angle is the defocusing and / or scattering of the light (18).

8. The display device (100) according to claim 1, characterized in that, The control unit (16) is designed to cause dynamic changes in the radiation characteristics of the display device (100) based on the observer's position and / or the displayed content.

9. The display device (100) according to claim 1, characterized in that, The control unit (16) is designed to cause dynamic changes in the radiation characteristics of the display device (100) based on detected sensor data and / or based on the displayed content.

10. A motor vehicle comprising a display device (100) according to any one of claims 1 to 9.

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