Projection display system for a vehicle

Abstract

The invention relates to a projection display device for a motor vehicle, comprising: a projection device which is designed to output image-carrying light in order to project a display image into the eye region of a vehicle occupant; an optical system which has at least one optical element and which is designed to focus the image-carrying light into the eye region such that the display image can be perceived in the eye region of the vehicle occupant; and a movable housing element which can be moved into a normal position, which ensures a projection operation, and a shielding position, wherein in the shielding position, the housing element is arranged between the display device and the at least one optical element.

Description

[0001] Description

[0002] Projection display system for a vehicle

[0003] The invention relates to projection display systems for implementing head-up displays in a vehicle. The invention also relates to measures for protecting projection display systems from direct sunlight.

[0004] Projection display systems typically feature a self-illuminating display device whose image is projected into the eyes of a vehicle occupant via a concave mirror and a cover plate on a windshield area or a combiner surface. Additional optical elements can be arranged between the display surface of the display device and the concave mirror if necessary.

[0005] The concave mirror is designed to project and focus the display image onto the retina of the vehicle occupant's eye, so that the occupant perceives the image plane as floating several meters in front of the vehicle. Conversely, direct light, particularly solar radiation, shining through the cover plate into the interior of the projection display system can cause the concave mirrors to focus the image, causing the display to heat up considerably due to the concentrated sunlight. Accordingly, measures must be taken to protect the display from excessive heating. Due to the vehicle's movement during operation, the exposure time to concentrated sunlight on the display is limited, so no further protective measures are necessary.In addition, protection usually also impairs functions, in particular the perceptibility of the display image, which is unacceptable during operation.

[0006] However, if the vehicle is parked, concentrated sunlight shining through the cover onto the concave mirror over an extended period can heat up the display and potentially damage it. Therefore, it is generally recommended to pivot the concave mirror when parked to ensure that concentrated sunlight does not fall onto the display surface of the display.

[0007] However, pivoting the concave mirror requires considerable room for movement, as the concave mirror extends over a large portion of the housing's dimensions and largely determines the depth of the projection display. Typically, the concave mirror is tilted forward in a parking position, so that incoming sunlight is directed by the concave mirror onto an interior wall of the housing, or incoming sunlight does not even reach the mirror surface of the concave mirror.

[0008] When pivoting the concave mirror, care must be taken during the design of the projection display system to ensure that the upper edge of the concave mirror does not collide with the usually curved cover plate. Therefore, a gap must be provided between the concave mirror and the cover plate, which increases the overall height of the projection display system.

[0009] The document DE 10 2011 105 689 A1 also discloses a display device comprising a liquid crystal display for displaying an image, a sensor system for determining an illuminance of an incident optical radiation and for determining a current position of the sun relative to the liquid crystal display, an adjustable shading device for protecting the liquid crystal display from the incident optical radiation, and a control unit which is configured to check whether the illuminance determined by the sensor system is above a predetermined threshold value and whether the current position of the sun falls within a predetermined angular range, and depending on a result of this check, to control the shading device such that it interrupts a beam path of a part of the optical radiation falling on the liquid crystal display.The shading device can comprise a diaphragm that can be folded in front of the liquid crystal display and / or into said beam path and / or a pivotable mirror arranged in said beam path of the incident optical radiation and serving to project the images displayed on the liquid crystal display.

[0010] The document DE 102 20 180 B4 discloses a head-up display for a vehicle, with a display device built into the dashboard, with which images are projected upwards through an opening in the dashboard for reflection on a screen arranged above the dashboard, wherein the images are displayed in the driver's field of vision, and with a cover unit which has a cover body which is movable to open and close the opening, and a shielding plate which is movable in the standing position and in the lying position and which, when the opening is open, is arranged upright in the standing position on the part of the edge of the opening facing the driver, so that the driver's direct view of and through the opening is blocked, wherein the shielding plate is laid flat along the upper side of the dashboard when the opening is closed in the lying position.

[0011] The latter solutions require considerable design effort to achieve shading of the display device. The object of the present invention is to provide a way, particularly when the vehicle is parked or stationary, to prevent sunlight incident on the projection display device from causing damage to the display device due to excessive heating.

[0012] This object is achieved by the projection display system according to claim 1.

[0013] Further embodiments are specified in the dependent claims.

[0014] According to a first aspect, a projection display device for a motor vehicle is provided, comprising:

[0015] - a projection device configured to emit image-bearing light for projecting a display image into an eye area of ​​a vehicle occupant,

[0016] - an optical system with at least one optical element designed to focus the image-bearing light into the eye area so that the display image is perceptible in the eye area of ​​the vehicle occupant;

[0017] - a movable housing part which can be adjusted into a normal position ensuring projection operation and a shielding position, wherein in the shielding position the housing part is arranged between the display device and the at least one optical element.

[0018] A projection display system for implementing a head-up display in a vehicle is typically installed in a dashboard. A transparent cover plate is located on the upper surface, protecting the projection optics and the display device. The projection display system focuses a display image from a self-illuminating display device via the concave mirror, directs it through the cover plate, and reflects the display light off a combiner surface or the windshield before focusing it in the eye of a vehicle occupant, particularly the driver. The focusing is achieved in such a way that the display image is perceived by the driver in a display plane that appears several meters in front of the vehicle. However, the installation space for a projection display device is very limited, particularly in small and mid-size vehicles.

[0019] As mentioned above, previous measures for implementing a shielding position to prevent excessive heating of the display device are disadvantageous in terms of the overall height of the projection display device and / or the design complexity. According to the above projection display device, a housing element of the projection display device is designed to be movable, so that this can be positioned as a shielding element in the beam path between the display device and the concave mirror when a protective condition exists or when the vehicle is inactive.

[0020] The at least one optical element may comprise a concave mirror or a converging lens.

[0021] The housing element, designed as a shielding element, is preferably pivotably mounted so that it can be moved, for example, by a mechanical toggle lever construction, and can be easily moved from an operating position to the protective position using a control actuator or manually. The core idea behind the above projection display device is to prevent the possibility of sunlight directly incident via the cover plate being directed onto the display surface by the concave mirror.

[0022] The housing element can comprise a base plate (base part) opposite a cover plate or a side wall of the housing. It can be provided that the base plate is arranged pivotably, in particular on a pivot axis, below a concave mirror as the at least one optical element.

[0023] A surface of the housing element facing away from the display device can be at least partially reflective.

[0024] Furthermore, the housing element can be automatically movable by means of an actuator, wherein a control unit is designed to adjust the shielding position when the vehicle is inactive, when the measured temperature of the display device is too high and / or when the projection device is switched off.

[0025] Embodiments are explained in more detail below with reference to the attached drawings. They show:

[0026] Figure 1 is a schematic cross-sectional view through a

[0027] Projection display device for a motor vehicle;

[0028] Figure 2 is a schematic perspective view of a

[0029] projection display device; and

[0030] Figure 3 is a schematic sectional view of the projection display device of Figure 2 in a shielding position.

[0031] Figure 1 schematically shows a cross-sectional view of a projection display device 1, such as a head-up display. The projection display device 1 comprises an optical projection device 2 and a cover with a cover plate 3. The projection display device 1 is essentially inserted into an opening 9 in an upper side 8 of an instrument panel 7 between a steering wheel and a windshield 5 such that it is essentially flush with or adjacent to the upper side 8.

[0032] The projection device 2 outputs a projection beam L in a suitable manner, which is directed in a projection direction P onto a display area 4 of a windshield 5 (alternatively, for example, onto the display area of ​​a combiner surface) of a motor vehicle. The projection device 2 comprises, in a known manner, a system of one or more mirrors 21, in particular a concave mirror and optionally lenses (not shown), and a display device 22.

[0033] The display device 22 may preferably be designed as a self-luminous LCD, MicroLED, OLED and the like to output a display image.

[0034] A display image output by the display device 22 is aligned as a projection beam L by the one or more mirrors 21 in the projection direction P and projected onto the display area 4. The projection beam L projected onto the display area 4 is reflected by the display area 4 and directed onto an eye region B of a vehicle occupant, so that an image is created in the eye of the vehicle occupant that corresponds to the display image of the display device 22 and by which information can be displayed.

[0035] A cover plate 3 can be provided directly on the projection device 2, which protects the projection device 2 from contamination by, for example, dust particles and ensures glare protection. The cover plate 3 can be substantially curved. However, flat or approximately flat shapes of the cover plate 3 are also conceivable. Figure 2 schematically shows a projection display device 1 in a housing 23. A display surface of the display device 22 is located at the rear end of a housing of the projection display device 1, with respect to the longitudinal direction of the vehicle.

[0036] At an opposite end of the housing 23, the mirror 21, in particular the concave mirror, is arranged so that the display image is reflected in the vertical direction so that it is directed onto the display area of ​​the windshield 5 or a combiner surface of the vehicle.

[0037] Furthermore, the housing 23 has two opposite side walls 24 and a base part 25, which enclose the optics of the projection device 2.

[0038] The angular arrangement of the concave mirror 21 is selected such that, depending on the inclination angle of the windshield, the display image is directed via the combiner surface into the eye area B of a vehicle occupant. The focal length of the concave mirror 21 is selected such that the display image is focused in the eye of the vehicle occupant.

[0039] When direct sunlight enters through the cover plate 3, it must be ensured that this is not directed via the concave mirror 21 onto the display surface of the display device 22, since the light-bundling effect can cause particular heat development in the area of ​​the display surface.

[0040] For this purpose, as shown in the sectional view of Figure 3, the base part 25 of the housing 23 can be pivotally mounted so that it can be pivoted with a free end in a shielding position into the beam path between the display surface and the concave mirror 21. In particular, the base part 25 of the housing 23 can be pivotally attached to a lower end of the concave mirror 21 and pivoted upwards using a toggle lever 26 or another adjustment mechanism so that the protruding end moves in front of the display surface of the display device 22. In this way, sunlight can be efficiently shielded from the display device 22.

[0041] The side of the pivotable base part 25 facing the concave mirror 21 can be designed to at least partially reflect sunlight, so that the absorption of sunlight does not result in excessive heat development in the area of ​​the base part 25. Furthermore, the distance between the base part 25 and the display surface ensures that even if the base part 25 heats up, no excessive heat can be introduced into the display device 22.

[0042] The adjustment of the base part 25 into the shielding position can be carried out automatically under the control of a control unit 27. The control unit 27 can be designed such that the shielding position is assumed when the vehicle is inactive (e.g., when stationary or not in use), when the temperature of the display device is too high (measured by a temperature sensor arranged there), and / or when the projection display device 1 is switched off.

[0043] List of reference symbols

[0044] 1 projection display device

[0045] Projection device 1 Mirror 2 Display device 3 Housing 4 Side walls 5 Base part 6 Toggle lever 7 Control unit 8 Position sensor

[0046] 3 Cover plate

[0047] 4 Display area

[0048] 5 Windscreen

[0049] 7 Instrument panel

[0050] 8 Top

[0051] 9 Opening

[0052] L projection beam

[0053] P Projection direction

Claims

Claims 1 . Projection display device (1) for a motor vehicle, comprising: - a projection device (2) designed to emit image-bearing light for projecting a display image into an eye area of ​​a vehicle occupant, - an optical system with at least one optical element (21) designed to focus the image-bearing light into the eye area so that the display image is perceptible in the eye area of ​​the vehicle occupant; - a movable housing element (25) which can be adjusted into a normal position ensuring projection operation and a shielding position, wherein in the shielding position the housing element (25) is arranged between the display device (22) and the at least one optical element (21).

2. Projection display device (1) according to claim 1, wherein the housing element (25) comprises a bottom part (25) opposite a cover plate (3) or a side wall (24) of the housing (23).

3. Projection display device (1) according to claim 2, wherein the base part is designed in particular as a base plate and is arranged pivotably on a pivot axis below a concave mirror as the at least one optical element (21).

4. Projection display device (1) according to claim 2, wherein the base part is designed in particular as a base plate and is pivotally mounted on a pivot axis below the display device (22).

5. Projection display device (1) according to claim 3 or 4, wherein the base part is pivotable into the interior of the housing (23).

6. Projection display device (1) according to one of claims 2 to 5, wherein a surface of the housing element (25) facing away from the display device (22) is at least partially reflective.

7. Projection display device (1) according to one of claims 1 to 6, wherein the at least one optical element (21) comprises a concave mirror or a converging lens.

8. Projection display device (1) according to one of claims 1 to 7, wherein the housing element (25) is automatically movable by means of an actuator, wherein a control unit is designed to adjust the shielding position by means of the actuator when the vehicle is inactive, when the measured temperature of the display device is too high and / or when the projection device is switched off.

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