Display apparatus

0001The invention relates to a display device having a display, which display at least temporarily at least locally is transparent and can be switched in this manner on the located by a viewer from behind the display device Background in the transparent area connected Advert reveals.

0002Display devices of the aforementioned type are sometimes Use in products of consumer goods, for. Example, in electronic grandfather clocks, which means this arrangement have a special design. Despite the strong desire in the field of fittings of motor vehicles, will find such transparent displays here so far no application, because the usually changing light conditions during operation a motor vehicle poor readability of such have ads result. For example, the display on the transparent display for easy readability designed in high ambient light, for example by black numerals on the otherwise transparent display are generated, the vehicle driver is able at a Ride in an environment weak external light, for example, not when driving through a tunnel, the display read more. The lack of visibility of conventional transparent display panels but is already in fluctuating recorded lighting conditions, for example at a ordinary cornering in a backlight situation, or from a backlight situation. Already here can the human eye, the information provided due to the fluctuating contrast and brightness significant difference not to capture satisfactory.

0003Starting from the problems and disadvantages of the prior Art, the invention has the object, a display device with an at least locally and temporarily to provide transparent display, which even in changing Light is easy to read.

0004According to the invention the object is achieved in that the display at least locally a switchable first filter comprising which diffuse between a substantially, at least partial transmission and a substantially transparent at least partial transmission back and forth is switchable. eliminates the possibility of the diffuse transmission the disruptive effect of changing ambient light conditions demand on the readability of the display. For example, in daylight by circuit the first filter in the diffusing mode homogeneously shining background are generated, on which the is shown to be conveyed information. Any increase in Brightness of the ambient light, is equally advantageous also the homogeneously glowing background brighter. The Contrast ratios remain due to the diffuse scattering Backlight highly constant despite changing lighting conditions. For operation in the dark or at night when brightness variations of the background to be less severe, it is expedient for the first to operate filter substantially transparent and optionally to illuminate additionally.

0005An advantageous development of the invention provides that the first filter is a polymer disperse liquid crystal cell is, or a polymer disperse liquid crystal display (PDLCD). A PDLCD lends itself extremely well read, because it does not require a polarizing filter and therefore particularly is bright. Moreover PDLCD's because it is one great accuracy with regard to the thickness of the liquid-dispersion layer not required, compared to other known Display devices relatively cheap producible.

0006Advantageously, the PDLCD in the display device according to the invention is formed matrix moderately controlled, so that the information to be displayed are displayed directly on this can. In addition or instead, the PDLCD can also controllable having segments, by means of which displayed icons are, for example, in design of a 7-segment display.

0007When using the display device according to the invention in a Motor vehicle as an information system, it makes sense, when the display device is arranged such that from the outside sunlight coming ambient light to pass through, and from the viewer can be perceived and the viewer of the from him located behind the display device landscape if desired in the transparent areas connected the display can be seen. If just the landscape are bothersome, the readability can means switching to diffusely scattering mode of the first are filter improves.

0008A particularly advantageous development of the invention before that in series to the first filter a second filter is arranged, which at least in regions between a first state in which it is substantially transmissive is and a second state in which it substantially is not transmissive, back and forth is switchable. As well as in the switching capability of the first filter is also in the The ability to switch the second filter not only the pure binary Setting two different states but useful preferred a gradual adjustment of the transparency and the scattering effect in the first filter and the transmission wherein the second filter. In this way, always optimal done adaptation to the environment situation and the user can, depending on his preference, for example by means a regulator, desired brightness and scattering effects choose which each sharp him a more or less provide contrast. is preferably instead, or in addition to the adjustment for the user an automatic Adjusting the scattering effect and the brightness the ambient light is preferred.

0009Suitably, the second filter is a liquid crystal cell (LCD), in particular formed as a positive-LCD. Here come in particular all types of transparent and efficient graphic Liquid crystal displays in question, preferably also ads with the capability of color display. Here is it is particularly useful if the second filter in the first state Not only is transmissive but essentially is transparent. If needed, so the background recognized by the display through.

0010For an excellent readability in all ambient light conditions, especially in the dark, it is useful, if by the viewer from behind the display a Backlight is disposed. Taking advantage of the special characteristics of the first filter is with advantage the arrangement of at least one lighting possible, which in Substantially perpendicular to the viewing direction laterally in irradiates the first filter. If the beam path of this Light source is substantially parallel to the display plane, finds a coupling towards the viewer only diffuse into the areas of place in which the first filter connected springy. In other areas, the viewer perceives no lighting true. can in this way to sense the information to be presented in the form of Show icons and similar designs. In one arrangement, a lighting behind the display is this appropriate transparent design, for example as a flat organic light emitting diode (OLED).

0011This makes for good legibility not a permanent manual correction required by the viewer, it is useful if the display device at least one sensor and comprising a controller, the sensor detects the ambient brightness measures and the result of measurement to the control the display device is delivered. The control of the Display device adjusts accordingly, the scattering effect of the first filter and the transmission of the second filter regions on the ambient light conditions and the displayed Information.

0012In addition to the display device and its advantageous developments proposes an invention for solving the problem A method for operating such a display device in front, wherein the ambient brightness is measured and Exceeds a certain brightness of the first filter essentially is switched diffuse and on a display the display device to be displayed information means one in the viewing direction in series to the first filter disposed second filter which at least in regions between a substantially transmissive, and a substantially nichttransmissiven state reciprocating switchable is and by connection of these areas to be displayed Information can be displayed, are displayed. This type of Control helps the display device according to the invention according to the object under changing light conditions to excellent readability. In a further development of the invention Procedure, the readability is improved when it is dark, when falling below the measured ambient brightness below a certain brightness of the second filter substantially transmissive or is switched transparent and on the display to be displayed by the information first filter which regions to display the displayed Information is driven display. Here, the lighting as described previously, by means of a transparent rear illumination of the display or a laterally radiating into the first filter light source expedient.

0013In the following, the invention is by means of embodiments with reference to the drawings only for clarity closer without limitation to the examples described explained. Show it:<dl tsize="8"><dt>Figure 1:</dt><dd>a schematic representation of an installation situation a display device according to the invention in a motor vehicle and the operation,</dd><dt>Figure 2:</dt><dd>a schematic representation of the construction of a Display device according to the invention in the ambient light fed transmitted light mode,</dd><dt>Figure 3:</dt><dd>a schematic representation of an inventive Display device having a transparent Backlight,</dd><dt>Figure 4:</dt><dd>a schematic representation of an inventive Display device having a laterally in the first filter irradiating light source,</dd><dt>Figure 5:</dt><dd>a schematic representation of the invention Method for operating an inventive Display device.</dd></dl>

0014In the illustration of Figure 1 is a display device according to the invention 1 is provided with the reference numeral 1 and in a motor vehicle 2 installed. A motor vehicle 2 leading 3 viewer of the display device 1 refers to the Display 4 the information excerpts shown in detail 5 true. When information 5 is the display the current driving speed of the motor vehicle 2, wherein the display 4 because of their transparency on the background recognize the display 4 located scenery 6 leaves.

0015Figure 2 shows a simple design of the invention Display apparatus 1 schematically. The display 4 of the display device 1 consists essentially of a first Filter 10 and a second filter 12, wherein the first filter 10 as polymer-Dispers display (PDLCD) and the second filter 12 is formed as a liquid crystal display. 13 The polymer disperse liquid crystal display 11 leaves with regard to change the transparency or the scattering effect in the manner for example, a complete transparency adjustable is, in which the landscape 6 by the Ambient light 7 can be seen clearly through the display 4 or that, for example, in completely diffuse scattering the display 54, shown up on any information, as homogeneously by the ambient light 7 lit display area appears.

0016The formation shown in Figure 3 of the present invention Display device 1 has, in addition to the first filter 10 and the viewing direction in the following second filter 12 a transparent, flat backlight 14 to, by means of which in the dark by means of a polymer disperse liquid crystal display 11 trained first Filter or formed as a liquid crystal display 13 second filter 12 illustrated information 5 viewers 3 can be displayed.

0017The formation shown in Figure 4 of the present invention Display device 1 provides that the side by means of a arranged lighting 15 the result matrix moderate Controlling the first filter 10 or the second filter 12 that as the polymer disperse liquid crystal display 11, or are formed as liquid crystal display 13, shown brought information 5 the viewer 3 for display will. The substantially parallel beam path of the illumination 15 is driven in the presentation of information 5 scattered areas and in this manner in the eye the viewer 3 directed. Not scattered light illumination 15 does not reach the viewer's eye third

0018Figure 5 shows an operation of the display device according to the invention 1 according to the method of the invention Controlling the display device 1 both in day mode 21 as well as in night mode 22 synoptic. The display device shown 1 substantially comprises in sequence of the viewer 3 of a positive liquid crystal display 23, a polymer-disperse Flüsigkristall display 24 and a transparent trained backlight 25. In addition, comprises the display device 1, a controller 26, which in cooperation with a sensor 27 for measuring the Ambient brightness control of the display 4 is used.

0019In the case of the daytime operation 21, the controller 26 switches due the measured brightness of the ambient light 7 Backlight from 25th Largely unimpaired penetrates the incident ambient light 7 backlight 25 and is incident on the first filter 10 or the Polymer disperse liquid crystal display 11, of the Control 26 is switched to the diffusely scattering mode. diffusely scattered from the first filter 10 applies the transmitted Light on the positive liquid crystal display 23, the from the controller 26, the matrix proper control commands has received graphical representation of a symbol 30th The Symbol 30 indicates to the viewer 3 on the display 4 Display device 1 as dark display backlit 31st

0020During nighttime operation 22, the control switches 26 due the 27 measured by the sensor, the darkness transparent trained a backlight 25th The happened from the backlight 25 emitted light the first filter 10, which matrix moderately from the controller 26 segmented graphics instructions for displaying a symbol 30 receives. The field of view of the symbol of the 30 Polymer disperse liquid crystal displays 24 is due to the switched control commands transmissive transparent and the area the background 31 transmissive diffusely scattering. The transmitted by the polymer disperse liquid crystal display 24 Light incident on the positive liquid crystal display 23, which switched transmissive transparent from the controller 26 is, so that the viewer 3 in the display 4 a View perceives having a bright symbol 30 and illuminated dark a result of diffuse scattering Background 31. If, instead of a subtle light an illumination 14, 25 a lateral coupling-out a lateral illumination 15 in the first filter 10 or the polymer disperse liquid crystal display 11, 24 is selected, results in a substantially dark background 31 and a bright symbol 30 with good contrast for the viewer. 3