EP1510995B1 - Display apparatus - Google Patents

Description

The invention relates to a display device with a display, which display is at least temporarily transparent at least partially transparent and can be seen in this way on the background of a viewer behind the display device background in the transparent switched area of the display.

Display devices of the aforementioned type are sometimes used in articles of the consumer goods industry, eg. As in electronic grandfather clocks, which have a special design by means of this arrangement.

From the EP-A-0778440 For example, a display is known which has, at least in some areas, a switchable first filter which can be switched back and forth between a substantially diffuse, at least partial transmission and a substantially transparent, at least partial, transmission.

However, the lack of readability of conventional transparent display fields is already noticeable in fluctuating light conditions, for example in the case of ordinary cornering in a backlight situation or out of a backlight situation. Even here, the human eye is no longer able to satisfactorily capture the information presented due to the strongly fluctuating contrast and the considerable brightness difference.

Based on the problems and disadvantages of the prior art, the invention has the object to provide a display device with an at least partially and temporarily transparent display, which is particularly well readable even in changing light conditions.

According to the invention the object is achieved with the features of claim 1.

According to the invention, a second filter is arranged in series with the first filter, which at least partially back and forth between a first state in which it is substantially transmissive and a second state in which it is substantially non-transmissive is switchable. As with the switchability of the first filter, it is not only the purely binary setting of two different states that makes sense in the switchability of the second filter, but also preferably a gradual adaptation of the transparency or the scattering effect in the first filter and the transmission in the second filter. In this way, an optimal adaptation to the ambient situation can always take place and the user can, depending on his preference, for example by means of a controller, set desired brightnesses and scattering effects, which each offer him a more or less sharp contrast. Preferably, instead of or in addition to the setting possibility for the user, automatic adaptation of the scattering effect and the brightness to the ambient light is preferred.

The possibility of diffuse transmission eliminates the disturbing influence of changing ambient light conditions on the readability of the display as needed. Thus, for example, in daylight by means of switching the first filter in the diffusely scattering mode, a homogeneous glowing background can be generated, on which the information to be conveyed is displayed. If the brightness of the ambient light increases, the homogeneously glowing background also becomes advantageously brighter. The contrast ratios remain highly constant due to the diffuse scattering of the backlight despite changing light conditions. For operation in the dark or at night, when brightness variations of the background less strong, it is expedient to operate the first filter substantially transparent and, if necessary, additionally to illuminate.

An advantageous development of the invention provides that the first filter is a polymer-dispersed liquid crystal cell, or a polymer-dispersed liquid crystal display (PDLCD). A PDLCD is extremely easy to read because it does not require a polarizing filter and is therefore particularly bright. In addition, since PDLCDs do not require much accuracy in the thickness of the liquid crystal dispersion layer, they are relatively inexpensive to produce over other known display devices.

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

When using the display device according to the invention in a motor vehicle as an information system, it makes sense if the display device is arranged so that from the outside einstrahlendes ambient light pass and can be perceived by the viewer and the viewer of him from behind the display device located landscape image on request in the transparent areas of the display. If just the landscape image are perceived as disturbing, the readability can be improved by switching to the diffusely scattering mode of the first filter.

Suitably, the second filter is designed as a liquid crystal cell (LCD), in particular as a positive LCD. In particular, all kinds of transparent and graphic-capable ones come here Liquid crystal displays in question, preferably also displays with the ability to color representation. In this case, it is particularly useful if the second filter is not only transmissive in the first state, but is essentially transparent. If necessary, the background can be seen through the display.

For excellent readability in all ambient light conditions, especially in the dark, it makes sense if the viewer from behind the display backlight is located. Taking advantage of the special properties of the first filter, the arrangement of at least one illumination is advantageously possible, which irradiates laterally into the first filter substantially perpendicular to the viewing direction. If the beam path of this light source is substantially parallel to the display plane, a decoupling in the direction of the viewer takes place only in the areas in which the first filter is connected in a diffusely scattering manner. In other areas, the viewer does not perceive any lighting. In this way it is useful to display the information to be displayed in the form of symbols and similar designs. In an arrangement of a lighting behind the display this is expediently transparent, for example, as a planar organic light emitting diode (OLED).

In order for a good readability not a constant manual correction by the viewer, it is expedient if the display device has at least one sensor and a controller, the sensor measures the ambient brightness and the result of the measurement is transmitted to the control of the display device. The control of the display device accordingly adjusts the scattering effect of the first filter and the transmission of the second filter in regions to the ambient light conditions and the information to be displayed.

In addition to the display device and its advantageous developments, the invention proposes a method for operating such a display device, in which the ambient brightness is measured and when a certain brightness is exceeded, the first filter is switched substantially diffuse and displayed on a display of the display device Information by means of a second filter arranged in the viewing direction in series with the first filter, which at least partially switchable back and forth between a substantially transmissive and a substantially non-transmissive state and by means of switching these areas the information to be displayed can be displayed. This type of control helps the display device according to the invention according to the task in changing light conditions to an excellent readability. In a further development of the method according to the invention, the readability is improved in the dark when falls below the measured ambient brightness under a certain brightness of the second filter is substantially transmissive or transparent and displayed on the display information by means of the first filter, which partially to display the information to be displayed is displayed. Here, the illumination, as described above, by means of a transparent rear illumination of the display or a laterally irradiating in the first filter light source appropriate.

Figur 1:

eine schematische Darstellung einer Einbausituation einer erfindungsgemäßen Anzeigevorrichtung in einem Kraftfahrzeug und die Wirkungsweise,

Figur 2:

eine schematische Darstellung des Aufbaus einer erfindungsgemäßen Anzeigevorrichtung im vom Umgebungslicht gespeisten Durchlichtbetrieb,

Figur 3:

eine schematische Darstellung einer erfindungsgemäßen Anzeigevorrichtung mit einer transparenten Hintergrundbeleuchtung,

Figur 4:

eine schematische Darstellung einer erfindungsgemäßen Anzeigevorrichtung mit einer seitlich in den ersten Filter einstrahlenden Lichtquelle,

Figur 5:

eine schematische Darstellung des erfindungsgemäßen Verfahrens zum Betrieb einer erfindungsgemäßen Anzeigevorrichtung.

In the following, the invention is based on embodiments with reference to drawings only for clarity without restriction to the examples described. Show it:

FIG. 1:

a schematic representation of a mounting situation of a display device according to the invention in a motor vehicle and the mode of action,

FIG. 2:

a schematic representation of the structure of a display device according to the invention in the transmitted by ambient light transmitted light mode,

FIG. 3:

a schematic representation of a display device according to the invention with a transparent backlight,

FIG. 4:

a schematic representation of a display device according to the invention with a laterally irradiating in the first filter light source,

FIG. 5:

a schematic representation of the inventive method for operating a display device according to the invention.

In the presentation of the FIG. 1 a display device 1 according to the invention is provided with the reference numeral 1 and installed in a motor vehicle 2. A viewer 3 of the display device 1 guiding the motor vehicle 2 perceives the information 5 shown in detail in detail on the display 4. In the information 5 is the display of the current driving speed of the motor vehicle 2, the display 4 can recognize the located in the background of the display 4 landscape image 6 due to their transparency.

FIG. 2 shows a simple design of a display device 1 according to the invention 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 is formed as a polymer dispersion display (PDLCD) and the second filter 12 as a liquid crystal display 13. The polymer-dispersed liquid crystal display 11 can be changed with respect to the transparency or the scattering effect in such a way that, for example, a complete transparency is adjustable, in which the landscape image 6 is clearly visible by the ambient light 7 through the display 4 or that For example, in the case of completely diffuse scattering, the display 54, except for any information shown, appears as a display area illuminated homogeneously by the ambient light 7.

In the FIG. 3 illustrated embodiment of a display device 1 according to the invention comprises, in addition to the first filter 10 and the second filter 12 following in the viewing direction, a transparent, planar backlight 14, by means of which in the dark by means of the polymer-dispersed liquid crystal display 11 formed first filter or the As a liquid crystal display 13 formed second filter 12 information shown 5 can be brought to the viewer 3 for display.

In the FIG. 4 illustrated embodiment of a display device 1 according to the invention provides that by means of a laterally arranged illumination 15, the matrix-based control of the first filter 10 or the second filter 12, which as a polymer-dispersed liquid crystal display 11, or as a liquid crystal display 13 are formed , displayed information 5 is brought to the viewer 3 for display. The essentially parallel beam path of the illumination 15 is scattered in regions which are controlled for displaying the information 5 and in this way is directed into the eye of the observer 3. Unscattered light of the illumination 15 does not reach the eye of the observer 3.

FIG. 5 shows a mode of operation of the display device 1 according to the invention according to the inventive method for controlling the display device 1 both in the daytime mode 21 as well as in the nighttime mode 22 synoptically. The illustrated display device 1 comprises substantially in an order from the viewer 3 a positive liquid crystal display 23, a polymer dispersed liquid crystal display 24, and a transparently formed backlight 25. In addition, the display device 1 comprises a controller 26 which is shown in FIG Cooperation with a sensor 27 for measuring the ambient brightness of the control of the display 4 is used.

In the case of daytime operation 21, the controller 26 turns off the backlight 25 due to the measured brightness of the ambient light 7. Largely unimpaired penetrates the incident ambient light 7, the backlight 25 and strikes the first filter 10 and the polymer-dispersed liquid crystal display 11, which is connected by the controller 26 in the diffusely scattering mode. Diffused by the first filter 10, the transmitted light strikes the positive liquid crystal display 23, which has received from the controller 26 the matrix control commands for the graphic representation of a symbol 30. The symbol 30 is shown to the viewer 3 on the display 4 of the display device 1 according to the invention as a dark representation in front of a light background 31.

During night operation 22, the controller 26 turns on the transparently formed backlight 25 due to the darkness measured by the sensor 27. The light emitted by the backlight 25 passes through the first filter 10, which receives matrix-segmented graphics commands from the controller 26 to represent a symbol 30. The area of the representation of the symbol 30 of the polymer-dispersed liquid crystal display 24 is transmissively transparent due to the control commands and the area of the background 31 is transmissively diffusely scattering. The light transmitted from the polymer dispersed liquid crystal display 24 strikes the positive liquid crystal display 23, which is transmissively transparent by the controller 26, so that the viewer 3 in the display 4 perceives a representation which is a bright symbol 30 If, instead of a background illumination of a lighting 14, 25 a lateral coupling of a lateral illumination 15 in the first filter 10 and the polymer-dispersed liquid crystal display 11, 24 is selected and a darker illuminated due to the diffuse scattering , a substantially dark background 31 and a bright icon 30 with good contrast results for the viewer 3.

Claims (15)

1. Display apparatus (1) having a display (4), it being possible to at temporarily switch at least regions of the said display (4) to the transparent state and in this way make the background (31) which is behind the display apparatus (1) as seen by a viewer (3) visible in the regions of the display (4) which have been switched to the transparent state, with at least regions of the display (4) having a switchable first filter (10) which can be switched back and forth between substantially diffuse at least partial transmission and substantially transparent at least partial transmission, characterized in that a second filter (12) is arranged in series with the first filter (10), it being possible to switch at least regions of the said second filter back and forth between a first state, in which it is substantially transmissive, and a second state, in which it is substantially non-transmissive.
2. Display apparatus according to Claim 1, characterized in that the first filter (10) is a polymer-dispersed liquid crystal display (11).
3. Display apparatus according to Claim 2, characterized in that the polymer-dispersed liquid crystal display (11) can be activated in the manner of a matrix.
4. Display apparatus according to Claim 2, characterized in that the polymer-dispersed liquid crystal display (11) has activatable segments, in particular for displaying symbols.
5. Display apparatus according to one of the preceding claims, characterized in that the second filter (12) is a liquid crystal display.
6. Display apparatus according to at least one of the preceding claims, characterized in that the second filter (12) is a positive liquid crystal display LCD (23).
7. Display apparatus according to at least one of the preceding claims, characterized in that the second filter (12) can be activated in the manner of a matrix.
8. Display apparatus according to at least one of the preceding claims, characterized in that the second filter (12) is substantially transparent in the first state.
9. Display apparatus according to at least one of the preceding claims, characterized in that a background lighting system (14) is arranged behind the display (4) as seen by the viewer (3).
10. Display apparatus according to at least one of the preceding claims, characterized in that at least one lighting system (15) shines laterally into the first filter (10) substantially perpendicular to the viewing direction.
11. Display apparatus according to Claim 8, characterized in that the lighting system (15) generates a substantially parallel beam path to the display plane.
12. Display apparatus according to at least one of the preceding claims, characterized in that the display apparatus (1) has at least one sensor (27) and a control means (26), the sensor (27) measures the ambient brightness, and the result of the measurement is transmitted to the control means (26) of the display apparatus (1).
13. Motor vehicle having a display apparatus (1) according to at least one of the preceding claims, characterized in that the display apparatus (1) is arranged such that ambient light (7) which shines in from the outside passes through and can be perceived by the viewer (3), and the viewer (3) can see the landscape (6), which is located behind the display apparatus (1) as seen by him, in the regions of the display (4) which have been switched to the transparent state.
14. Method for operating a display apparatus (1) according to at least one of the preceding claims, characterized in that

    - the ambient brightness is measured, and

    - when a specific brightness is exceeded, the first filter (10) is switched to the substantially diffuse state and information (5) which is to be represented on the display (4) is displayed by means of a second filter (12), which is arranged in series with the first filter (10) in the viewing direction and at least regions of which second filter can be switched back and forth between a substantially transmissive state and a substantially non-transmissive state, and the information (5) to be represented can be displayed by means of switching these regions.
15. Method according to Claim 14, characterized in that

    - the ambient brightness is measured, and

    - when a specific brightness is undershot, the second filter is switched to the substantially transmissive or transparent state and information (5) which is to be displayed on the display (4) is displayed by means of the first filter, at least regions of which first filter are activated to display (4) the information to be displayed.

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