DE102014214946A1 - Display device for a particular motor vehicle and method for operating such a display device - Google Patents

Abstract

The invention relates to a display device (1), in particular in a motor vehicle, comprising an imaging unit (2) for generating image content to be displayed, imaging optics for influencing radiation beams emitted by the imaging unit (2) in a beam path (12) and for projecting the radiation beams via a windshield or a combiner in a field of view of a driver or other vehicle occupants for generating a virtual image, and an optical filter (6), characterized in that the optical filter (6) for reducing a heat input by sunlight to the imaging unit (2 ) is arranged in the beam path (12) and is selectively transmissive such that the transmission of sunlight is reduced.

Description

State of the art

The present invention relates to a display device, in particular for a motor vehicle, and a method for operating such a display device. In particular, the display device may be a head-up display (HUD), which is used, inter alia, in vehicles to display to the driver by mirroring a virtual image in his field of view information about the vehicle condition or speed information, navigation aids or driver assistance functions , There is generally the problem that sunlight passes through or through the windshield and the optics of the head-up display to the imaging unit of the head-up display and heats them.

Known solutions to this problem are, for example, shutters that are closed from a certain temperature inside the head-up display or from a certain intensity of sunlight and thereby protect the imaging unit from excessive heating.

In the DE 10 2011 105 689 A1 discloses a head-up display with a sensor system for determining an intensity of incident radiation and a shutter for protecting the head-up display from the incident radiation.

Furthermore, in the DE 103 53 156 B4 discloses a shutter for a head-up display, which is variable in shape and size and thereby on the one hand can vary the incidence of sunlight on the imaging unit, but on the other hand limits the size of the image to be displayed.

Disclosure of the invention

• – eine bildgebende Einheit (2) zur Erzeugung darzustellender Bildinhalte,
• – eine Abbildungsoptik zur Beeinflussung von der bildgebenden Einheit (2) emittierten Strahlenbündeln in einem Strahlengang (12) und zur Projektion der Strahlenbündel über eine Windschutzscheibe oder einen Combiner in ein Sichtfeld eines Fahrers oder anderer Fahrzeuginsassen zur Erzeugung eines virtuellen Bildes, sowie
• – ein optisches Filter (6), dadurch gekennzeichnet, dass das optische Filter (6) zur Verringerung eines Wärmeeintrags durch Sonnenlicht auf die bildgebende Einheit (2) in dem Strahlengang (12) angeordnet ist und derart selektiv transmissiv ist, dass die Transmission von Sonnenlicht verringert wird.

The device according to the invention is based on a display device, in particular for a motor vehicle, having the following features:

• - an imaging unit ( 2 ) for generating image content to be displayed,
• An imaging optics for influencing the imaging unit ( 2 ) emitted beams in a beam path ( 12 ) and for projecting the beams through a windshield or a combiner into a field of vision of a driver or other vehicle occupant to create a virtual image, and
• An optical filter ( 6 ), characterized in that the optical filter ( 6 ) for reducing heat input by sunlight to the imaging unit ( 2 ) in the beam path ( 12 ) and is selectively transmissive such that the transmission of sunlight is reduced.

A display device can be understood to mean any type of displays or displays, in particular head-up displays. The imaging unit generates the image content to be displayed. It generally has a flat screen, which may in particular be a TFT-controlled liquid crystal display (TFT = Thin Film Transistor: thin-film transistor). The non-self-luminous liquid crystal display is illuminated by an external light source, which may be configured, for example, as an LED module or laser diode module, whereby the image contents to be displayed are generated. By a bundle of rays one can understand the sum of all the light rays emitted by the imaging unit. A beam path can be understood as a geometric course of a radiation through the display device. A combiner can be understood as meaning a semipermeable glass pane which is fixed in a region of the field of vision of the driver on the dashboard or which, if required, is moved out of the dashboard into an area of the field of vision of the driver. An optical filter can be understood to mean a planar element, such as a rectangular or round plate made of a material with specific optical properties. Under a selectively transmissive filter can be understood that the filter has certain advantageous transmission properties. For example, these transmission properties are such that the entire spectrum of the sunlight is attenuated by the filter except for certain wavelength ranges in which the light sources of the imaging unit mainly emit light. The introduction of such an optical filter into the beam path has the advantage that it prevents the heating by sunlight of the display device or the components contained therein, in particular the imaging unit and that emitted by the imaging unit beams and thus the quality of the image produced by the optical filter is not affected. Only the spectral properties of a virtual image are thereby possibly influenced, depending on the design of the filter.

The measures listed in the dependent claims advantageous refinements and improvements of the independent claim device are possible.

Appropriately, it is provided in one embodiment of the invention that the filter is an interference filter. Under an interference filter can a filter are understood, the carrier material consists for example of a transparent glass or of a transparent plastic, wherein the carrier material is provided at least on one side with a plurality of periodically alternating, different dielectric layers. The periodically alternating dielectric layers differ in particular by their refractive index. The layer thicknesses of the individual layers are essentially a fraction of the wavelength of the light. The advantages of an interference filter include the fact that the optical properties of the interference filter can be set very precisely by the choice of the dielectric materials and by the variable layer thicknesses.

Furthermore, the filter can advantageously be designed as an absorption filter. Absorption filters consist essentially of a transparent carrier material such as glass or plastic, to which organic or inorganic compounds have been added. These organic or inorganic additives absorb light of a certain wavelength, or a specific wavelength range, while transmitting other wavelengths or wavelength ranges. It is also conceivable to combine several absorption filters with different absorption properties in order to achieve the desired selective transmissivity of the optical filter. The advantages of absorption filters are, among other things, that they are technically simple to manufacture and therefore cost-effective.

In a further embodiment of the invention, the filter is positioned in the beam path of the display device such that the part of the radiation or of the light which is reflected by the filter is deflected out of the beam path. This can be accomplished, for example, by positioning the filter in the beam path such that the angle between a main beam of the beam path and a solder of the filter is not equal to zero. This prevents light emitted from the imaging unit from being reflected back into the imaging unit. It is also prevented that sunlight or solar radiation is reflected through the optics of the display device and the windshield towards the driver and can dazzle.

Advantageously, the filter is arranged between the imaging unit and a covering glass terminating the display device in the beam path. This ensures that incident through the cover glass incident sunlight or sunlight on the filter and is absorbed or reflected there so that it can not get further to the imaging unit and it can heat too much.

Furthermore, it is provided in a further embodiment of the invention that the filter is designed as the cover glass finalizing the display device. This ensures, for example, that sunlight or solar radiation does not even get into the display device, but is already absorbed or reflected on the cover glass.

In a further advantageous embodiment of the invention it is provided that the filter is movable in the beam path. This can for example be realized in that the filter is rotatably or displaceably mounted, and can be rotated or pushed over a mechanical, electro-mechanical or pneumatic device in the beam path. The drive of this device can be realized, for example, as an electric motor, in particular as a stepping motor or as a reluctance motor. This has the advantage that in certain environmental conditions where no direct sunlight enters the display device, such as in overcast skies, at dusk or at night, the filter can be removed from the beam path to increase the contrast and brightness of the display increase.

It is further contemplated that the selective transmissivity of the filter is tuned to the emission wavelength of the imaging unit such that the filter for the emission wavelengths of light emitted by the imaging unit is substantially transmissive and substantially reflective or absorbing for other wavelengths is. As a result, only a small part of the sunlight or the solar radiation, namely the wavelength range of the light which is also emitted by the imaging unit, passes through the filter. This protects the imaging unit from overheating.

It is also conceivable that the intensity of the image contents to be displayed by the imaging unit is selected as a function of the setting of the filter. Depending on whether the filter is moved completely into the beam path, or whether it is screwed, for example, only at a certain angle, the dimming of the imaging unit is adjusted so that for a driver, the brightness of the virtual image advantageously remains almost the same. This should be z. B. during installation of the display device in the vehicle they are calibrated once to compensate for the angular dependence of the setting of the filter in the beam path in the subsequent use can.

Furthermore, it is provided that the color of the image content to be displayed by the imaging unit is selected as a function of the setting of the filter. Because depending on the angle at which the filter in the beam path This affects both the level of transmissivity and the wavelength range of the transmissivity, especially in the case of an interference filter. This means that the imaging unit has to adjust the color of the image information to be displayed, depending on the setting of the angle of the filter in the beam path, to the transmission properties of the filter at this angle. It is also conceivable that when using a neutral density filter, or gray filter, which is transmissive only for the visible wavelength range, the imaging unit generates the image content to be displayed in gray levels.

This ensures that no image content, such as a hazard warning, is filtered out through the filter. Conveniently, particularly important image contents, such as warnings, etc., highlighted in another way, for example by an enlarged view, a representation with a wider outline, a brighter presentation or flashing.

Again, z. B. during installation of the display device in the vehicle they are calibrated once to compensate for the angular dependence of the setting of the filter in the beam path in the subsequent use can.

Appropriately, it is provided that the filter in at least one of the wavelength ranges from 445 nm to 495 nm, from 520 nm to 570 nm and / or 605 nm to 655 nm transmissivity of greater than 85%, preferably greater than 90%, particularly preferred greater than 95%. These wavelength ranges correspond, for example, to the LED light sources that can be used in the imaging unit. The better the LED emission wavelength ranges match the transmission ranges of the filter and the higher the transmissivity in these ranges, the higher the contrast of the display and the lower the heat input through the solar radiation passing through the filter in these transmission windows.

Furthermore, it is conceivable that the transmission ranges of the filter are made even narrower by the use of laser diodes as light sources for the imaging unit. As a result, when using laser light sources, a particularly efficient filter can be used which on the one hand absorbs or reflects a large part of the solar radiation and on the other hand transmits the light of the image generator to a large extent. If the filter is transmissive in all three wavelength ranges, a polychromatic image can be displayed.

It is also conceivable, for example, for the filter to be transparent only to green light, for example from 520 nm to 570 nm. Since the spectral sensitivity of the human eye is highest, especially in this wavelength range, a high contrast of the display is achieved. It will then essentially display a monochromatic image.

• – Erzeugen darzustellender Bildinhalte durch eine bildgebende Einheit,
• – Beeinflussen der von der bildgebenden Einheit emittierten Strahlenbündel in einem Strahlengang durch eine Abbildungsoptik,
• – Projizieren der Strahlenbündel über eine Windschutzscheibe oder einen Combiner in ein Sichtfeld eines Fahrers oder anderer Fahrzeuginsassen zur Erzeugung eines virtuellen Bildes, sowie
• – Verringern eines Wärmeeintrags durch Sonnenlicht auf die bildgebende Einheit durch ein optisches Filter, das in dem Strahlengang angeordnet ist und derart selektiv transmissiv ist, dass die Transmission von Sonnenlicht verringert wird.

The approach described here creates a method for operating a display device, the method comprising the following steps:

• Generating image content to be displayed by an imaging unit,
• Influencing the radiation beam emitted by the imaging unit in a beam path through imaging optics,
• Projecting the beam through a windshield or a combiner into a field of vision of a driver or other vehicle occupant to create a virtual image, and
• - Reduction of heat input by sunlight on the imaging unit by an optical filter, which is arranged in the beam path and is selectively transmissive, that the transmission of sunlight is reduced.

The above-mentioned advantages arise accordingly from the method claim.

Brief description of the drawings

Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description.

Show it

1 a schematic representation of a display device according to the invention with a movable optical filter;

2 a schematic representation of the operation of an absorption filter;

3 a schematic representation of an interference filter;

4 an exemplary transmission diagram of an optical filter; and

5 a schematic representation of a possible embodiment of a display device according to the invention with a filter as cover glass.

Embodiments of the invention

In 1 is a schematic representation of an exemplary display device according to the invention 1 with a movable optical filter 6 shown. The display device 1 includes one Imaging unit 2 , which in turn, for example, from an LED light source 4 , from a heat sink 5 , and a liquid crystal display 3 , is constructed. The display device 1 further comprises the movable optical filter 6 that is via a mechanical, electromechanical or pneumatic device 7 in the beam path 12 can be moved.

Furthermore, the display device comprises 1 in the embodiment shown here a light sink 8th on which of the optical filter 6 reflected light or radiation impinges and absorbs the incident light, or the radiation. Furthermore, the display device comprises 1 a plane mirror 9 and a concave mirror 10 , as well as a housing 14 in which the aforementioned elements of the display device 1 are located. Instead of the mirror construction shown here, the light path can also be formed in any other way.

The device 7 with which the optical filter 6 in the beam path 12 can be moved, for example, as a turning device, as in 1 shown, but also designed as a displacement device.

Light that from the LED light source 4 is emitted, hits the liquid crystal display 3 that generates the image to be displayed. However, it is also conceivable that instead of an LED light source other light sources, such as laser diodes, are used. The beam that the imaging unit 2 leaves, hits the optical filter 6 which is just transmissive to the wavelength ranges that make up the beam which is the imaging unit 2 leaves. The beam passes along the beam path 12 and hits the plane mirror 9 on, the beam path 12 on the concave mirror 10 deflects, which in turn the beam path 12 reflected out of the display device. The original of the imaging unit 2 emitted radiation beam runs along the beam path 12 and then hits the windshield 11 on, which reflects the beam in the direction of the viewer. The resulting virtual image gives the viewer the impression that it is at a certain distance, for example two to five meters in front of the windshield.

It is possible that sunlight, which is the windshield 11 happens in the display device 1 in occurs. Along the beam path 12 it will now be on the concave mirror 10 and the plane mirror 9 in the direction of the imaging unit 2 reflected. Before it enters the imaging unit 2 can enter, the light is through the optical filter 6 in one embodiment, either absorbed as an absorption filter or reflected in one embodiment as an interference filter. In the case of an interference filter, the light is deflected out of the beam path and onto the light sink 8th reflected back.

In one possible embodiment of the invention, the optical filter 6 and the device 7 for moving the optical filter 6 in the beam path 12 at any point in the beam path 12 after the imaging unit 2 be arranged.

In a further possible embodiment of the invention, the optical filter 6 permanently in the beam path 12 remain. This can be done on the rotating device 7 with which the optical filter 6 is rotated in the beam path, be waived.

2 shows schematically the operation of an absorption filter 21 , The visible special area of the sunlight is very small in comparison to the total spectral width of the sunlight. The unfiltered solar radiation is therefore in 2 as a thick arrow 20 shown. It hits the absorption filter 21 which absorbs a large part of the incident solar radiation and according to the transmission property of the absorption filter 21 only a small part of filtered solar radiation lets through, here as a thin arrow 25 shown.

Analogous to 2 shows 3 a schematic representation of the operation of an interference filter 22 , Unfiltered solar radiation hits, as a thick arrow 20 shown on the interference filter 22 that reflects as much of the unfiltered solar radiation as possible. The reflected solar radiation, as a middle arrow 26 is displayed, depending on the angle at which unfiltered solar radiation on the interference filter 22 impinges, reflected back in a certain direction. Only a fraction of the original on the interference filter 22 incident unfiltered solar radiation, the filter passes as filtered solar radiation, here as a thin arrow 25 shown.

In 4 For example, a transmission diagram of an optical filter is shown. On the X-axis, a wavelength range between 400 nm and 800 nm is plotted. The transmissivity or transmission in percent is plotted on the Y axis. The filter in question has so-called transmission windows for the wavelength ranges from 445 nm to 495 nm, from 520 nm to 570 nm and from 605 to 655 nm. This means that light from these wavelength ranges can pass through the filter almost unhindered, whereas other wavelength ranges are blocked by the filter.

In 5 is an alternative embodiment of the display device 1 out 1 to see. This is in addition to the imaging unit 2 to the plane mirror 9 , to the concave mirror 10 also a cover glass 13 shown. The cover glass 13 that the display device 1 is here as the optical filter 6 designed. The optical filter 13 is stationary on or in the housing 14 the display device 1 attached or installed or integrated. This has the advantage that sunlight or solar radiation not even in the display device 1 can enter, but already through the cover glass 13 is blocked. Usually, cover glass 13 curved executed. This ensures the suppression of disturbing, direct sun reflexes in the Eyebox, so the area in which the driver can perceive the entire picture.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102011105689 A1 [0003]
• DE 10353156 B4 [0004]

Claims (12)

Display device ( 1 ), in particular in a motor vehicle, comprising - an imaging unit ( 2 ) for generating image content to be displayed, - imaging optics for influencing the imaging unit ( 2 ) emitted beams in a beam path ( 12 ) and for projecting the beams across a windshield or a combiner into a field of vision of a driver or other vehicle occupant to produce a virtual image, and - an optical filter ( 6 ), characterized in that the optical filter ( 6 ) for reducing heat input by sunlight to the imaging unit ( 2 ) in the beam path ( 12 ) and is selectively transmissive such that the transmission of sunlight is reduced. Display device ( 1 ) according to claim 1, characterized in that the optical filter ( 6 ) is designed as an absorption filter. Display device ( 1 ) according to claim 1, characterized in that the optical filter ( 6 ) is designed as an interference filter. Display device ( 1 ) according to one of the preceding claims, characterized in that the optical filter ( 6 ) in the beam path ( 12 ) of the display device ( 1 ) is arranged that of the optical filter ( 6 ) reflected light from the beam path ( 12 ) is distracted. Display device ( 1 ) according to one of the preceding claims, characterized in that the optical filter ( 6 ) between the imaging unit ( 2 ) and a display device ( 1 ) final coverslip ( 13 ) in the beam path ( 12 ) is arranged. Display device ( 1 ) according to one of claims 1 to 4, characterized in that the optical filter ( 6 ) than the display device ( 1 ) final cover glass ( 13 ) is configured. Display device ( 1 ) according to one of claims 1 to 5, characterized in that the optical filter ( 6 ) in and / or out of the beam path ( 12 ) is movable. Display device ( 1 ) according to one of the preceding claims, characterized in that the selective transmissivity of the optical filter ( 6 ) to the emission wavelengths of the imaging unit ( 2 ) is tuned such that the optical filter ( 6 ) for the emission wavelengths of the imaging unit ( 2 ) is transmissive and reflective or absorbing for other wavelengths. Display device ( 1 ) according to one of the preceding claims, characterized in that the intensity of the imaging unit ( 2 ) image content depending on the setting of the filter ( 6 ) is selected. Display device ( 1 ) according to one of the preceding claims, characterized in that the color of the imaging unit ( 2 ) image content depending on the setting of the filter ( 6 ) is selected. Display device ( 1 ) according to one of the preceding claims, characterized in that the optical filter ( 6 ) in at least one of the wavelength ranges from 445 nm to 495 nm, from 520 nm to 570 nm and or 605 nm to 655 nm has a transmissivity of greater than 85%, preferably greater than 90%, particularly preferably greater than 95%. Method for operating a display device ( 1 ), the method comprising the following steps: - generating image content to be displayed by an imaging unit ( 2 ), - influencing that of the imaging unit ( 2 ) emitted beams in a beam path ( 12 by imaging optics, projecting the beams across a windshield or combiner into a field of view of a driver or other vehicle occupant to create a virtual image, and reducing heat input by sunlight to the imaging unit. 2 ) through an optical filter ( 6 ), which in the beam path ( 12 ) and is selectively transmissive such that the transmission of sunlight is reduced.

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