DISPLAY DEVICE FOR A MOTOR VEHICLE

Abstract

In a motor vehicle, a display device has a display area displaying an image projected by an optical device by way of a reflection area as a virtual image. The optical device has at least one reflector and an actuator which moves the reflector. The actuator includes a shape memory material, which is designed to be deformed by a temperature-dependent phase transition and thereby move the reflector. By the provision of a thermal shape memory actuator that functions without an electric current, the optical path can be changed, so that overheating of internal temperature-sensitive components of the display device can be prevented in a way that is particularly inexpensive and efficient in terms of installation space and it is also possible to dispense with electronic sensing, evaluation and activation entirely.

Claims

1-7. (canceled)

8. A display device for a motor vehicle, the display device, comprising: a display with a display area configured to display an image; and an optical device configured to project the image displayed on the display area, the optical device having at least one reflector, and an actuator, configured to move the at least one reflector, the actuator including a shape memory material responding to temperature change with a temperature-dependent phase transition and thereby moving the at least one reflector, the optical device configured to project the image displayed on the display area in at least one direction of projection when the at least one reflector is in a first position, the actuator configured to move the at least one reflector out of the first position so that light impinging on the optical device opposite to the direction of projection is not incident on the display area, the reflector being formed as a reflective coating on a reflection area of the actuator.

9. The display device as claimed in claim 8, wherein the actuator is configured to move the reflector, when the temperature goes above a first predefined limit temperature, out of the first position.

10. The display device as claimed in claim 9, wherein the actuator is configured to move the reflector, when the temperature goes below a second predefined limit temperature, into the first position.

11. The display device as claimed in claim 10, wherein the reflector is mounted rotatably about an axis of rotation, the actuator being configured to rotate the reflector about the axis of rotation.

12. The display device as claimed in claim 9, wherein the reflector is mounted rotatably about an axis of rotation, the actuator being configured to rotate the reflector about the axis of rotation.

13. The display device as claimed in claim 8, wherein the reflector is mounted rotatably about an axis of rotation, the actuator being configured to rotate the reflector about the axis of rotation.

14. The display device as claimed in claim 8, wherein the actuator is configured to move the reflector, when the temperature goes below a predefined limit temperature, into the first position.

15. A motor vehicle with a display device, comprising: a display with a display area configured to display an image; and an optical device having at least one reflector configured to project the image displayed on the display area in at least one direction of projection when in a first position, and an actuator, including a shape memory material responding to temperature change with a temperature-dependent phase transition causing the at least one reflector to move out of the first position so that light impinging on the optical device opposite to the direction of projection is not incident on the display area, the reflector being formed as a reflective coating on a reflection area of the actuator.

16. The motor vehicle as claimed in claim 15, further comprising a windshield, and wherein the display device is arranged in the motor vehicle so that the optical device is configured to project the image displayed on the display area onto the windshield.

17. The motor vehicle as claimed in claim 15, wherein the actuator is configured to move the reflector, when the temperature goes above a first predefined limit temperature, out of the first position.

18. The motor vehicle as claimed in claim 17, wherein the actuator is configured to move the reflector, when the temperature goes below a second predefined limit temperature, into the first position.

19. The motor vehicle as claimed in claim 18, wherein the reflector is mounted rotatably about an axis of rotation, the actuator being configured to rotate the reflector about the axis of rotation.

20. The motor vehicle as claimed in claim 17, wherein the reflector is mounted rotatably about an axis of rotation, the actuator being configured to rotate the reflector about the axis of rotation.

21. The motor vehicle as claimed in claim 15, wherein the reflector is mounted rotatably about an axis of rotation, the actuator being configured to rotate the reflector about the axis of rotation.

22. The motor vehicle as claimed in claim 15, wherein the actuator is configured to move the reflector, when the temperature goes below a predefined limit temperature, into the first position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] These and other aspects and advantages, features and details will become more apparent and more readily appreciated from the following description of the exemplary embodiments, taken in conjunction with the accompanying drawings of which:

[0019] FIG. 1 is a schematic representation of a display device arranged in a motor vehicle with a thermal shape memory actuator in a starting position below a limit temperature for changing the optical path in the display device according to an exemplary embodiment; and

[0020] FIG. 2 shows a schematic representation of the display device according to FIG. 1 with the thermal shape memory actuator in its expanded position above the limit temperature according to an exemplary embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0021] Reference will now be made in detail to the preferred embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout.

[0022] FIG. 1 and FIG. 2 show a schematic representation of a display device 10 arranged in a motor vehicle with an imaging unit 12 and an optical device 14, which has an adjustable reflector 14a, according to an exemplary embodiment. The imaging unit 12 may in this case have a display with a display area, on which an image to be displayed is output. The image is then projected by way of the optical device 14 onto the windshield 16 of the motor vehicle, so that it is perceived by a user in the driver's seat as a virtual image. In this example, the optical device 14 has a first reflector 14a of a planar form and a second reflector 14b of a concave shape. These are arranged such that light emitted by the imaging unit 12 is directed via the first reflector 14a onto the second reflector 14b and from the latter onto a predetermined area of the windshield 16 that can optionally be set by way of the optical device 14, for example by way of the setting of the reflectors 14a and/or 14b. Conversely, sunlight 20 radiated in through the windshield 16 can consequently also be directed via the second reflector 14b onto the first reflector 14a and via the latter onto the imaging unit 12, in particular the display.

[0023] In order then to prevent damage to the display or else other temperature-sensitive components of the imaging unit 12, an alteration of the path of rays in dependence on certain temperature parameters is provided. For this purpose, one of the reflectors 14a, 14b or mirror elements, in this example the first reflector 14a, can be adjusted by an actuator 18 in such a way that the light 20 entering from outside no longer falls directly on temperature-sensitive components, such as for example the display, of the imaging unit 12. It is particularly advantageous here that this actuator 18 is formed as a thermal shape memory actuator 18 that functions without an electric current. On the basis of its principle, this actuator changes its shape/length when the temperature goes above a certain limit temperature, and can thus turn or pivot the first reflector 14a by a suitable kinematic mechanism. If the temperature goes below a limit temperature, it resumes its original state in terms of shape/length and consequently moves the first reflector 14a or the mirror into its starting position.

[0024] The actuator 18 in this case includes a shape memory material, such as for example a shape memory alloy, or is formed completely from a shape memory material which, in dependence on its own temperature, is deformed by a phase transition when the temperature goes above and below a limit temperature. In this example, the actuator 18 expands in the direction of its longitudinal extent when the temperature goes above a limit temperature as a result of the solar radiation 20 radiating in, as represented in FIG. 2, and thereby rotates the reflector 14a about the bearing point, or the bearing axis 22, at which the first reflector 14a is rotatably mounted, so that the sunlight 20 radiated onto the second reflector 14b is at least largely not directed via the first reflector 14a onto the display. If the temperature of the actuator 18 drops again and, as a consequence, goes below a certain second limit temperature, the actuator 18 resumes its original shape, and consequently the first reflector 14a resumes its starting position, as represented in FIG. 1. The second limit value may in this case lie below the first limit value, which is dictated by the hysteretic properties of shape memory alloys. Depending on the material used, the shaping, size, volume and forming of the actuator 18, the first and second limit values may be predefined and also coincide within a predefined limit. Furthermore, as a result the amount of the change in shape or the change in length, and consequently the angle by which the first reflector 14a is rotated, can also be predefined. For example, the actuator 18 may in this case be formed in the manner of a spring or spiral, whereby its change in shape during the phase transition can be converted particularly effectively into a change in length for the movement of the first reflector 14a.

[0025] As an alternative or in addition, the actuator 18 may also be provided for the movement of the second reflector 14b, in order to change the optical light path when the temperature goes above a limit temperature. Both reflectors 14a and 14b may also be coupled with a respective shape memory actuator 18. In addition, depending on the application, the display device 10 may also have just one reflector, which is moved by the actuator 18, or else more than two reflectors, then at least one of these reflectors being moved by the actuator 18. The reflectors may also be formed differently than in the way presented here in the surface geometry of their reflective surfaces, such as for example planar, concave, convex, and in their arrangement in relation to one another.

[0026] Altogether, the invention thus provides a display device which, by the provision of a thermal shape memory actuator that functions without an electric current, can prevent overheating of the display or other internal temperature-sensitive components of the display device in a way that is particularly inexpensive and efficient in terms of installation space. By forming the actuator in this way, it consequently undertakes the sensory and actuary elements of the previously known methods and it is possible to dispense with electronic sensing, evaluation and activation entirely. The way in which the actuator functions completely without requiring an electric current ensures the protection of the internal temperature-sensitive components at any time, even when the vehicle is parked, and altogether a particularly energy-saving, purely mechanical protective device is provided by the shape memory actuator.

[0027] A description has been provided with particular reference to preferred embodiments thereof and examples, but it will be understood that variations and modifications can be effected within the spirit and scope of the claims which may include the phrase at least one of A, B and C as an alternative expression that means one or more of A, B and C may be used, contrary to the holding in Superguide v. DIRECTV, 358 F3d 870, 69 USPQ2d 1865 (Fed. Cir. 2004).