Abstract:
A control and display unit for differentiated colored marking of texts or symbols provided with a monochrome LC-display and a backlight of the LC-display. A film, which is provided with a microstructure on at least one side, is arranged between the backlight and the LC-display.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to an operating and display unit for differentiated colored marking of texts or symbols, with a monochrome LC display (liquid crystal display) and direct or indirect backlighting. 
     The colored marking of texts or symbols by means of color LC displays such as CSTN (color super twisted nematic) or TFT (thin film transistor) is known. However, these are expensive, and not suitable for all environmental conditions. 
     From U.S. Pat. No. 5,694,793, LC display systems for washing machines are known, whereby a distinction is made between passive and active illumination systems. Common to all the forms of embodiment described is a very complex structure, together with the lack of a possibility for being able to illuminate an individual display area with different colors, depending on a program. 
     SUMMARY OF THE INVENTION 
     One object of the invention consists in devising a low-price operating and display unit with which the differentiated colored marking of texts or symbols in a monochrome LC display is possible. Another object is to give greater design freedom in the structuring of operating and display units, in particular in the choice of position, dimension and color of the colored marking. Further objects are to achieve improved visualization of different program states compared to monochrome LC displays, and to provide a low-cost way of enhancing an LC display with monochrome backlighting into a display and operating unit with several display colors. 
     These objects are achieved by an operating and display unit for differentiated colored marking of texts or symbols, with a monochrome LC display and backlighting of the LC display, in which a foil is provided between the backlight and the LC display, the foil having a microstructure. The microstructure can be on one side or on several sides of the foil. Further, the microstructure can be provided within the foil, for example by particles which form the microstructure. A uniform alignment, for example of magnetic particles, can be effected by means of a magnetic field while the foil is being manufactured. In addition, the microstructure can be provided directly on the backlight or on the LC display. It is then possible to forgo any separate foil with microstructure. 
     The backlighting can be implemented, preferably as a single color, for example by means of LEDs (light emitting diodes) EL foils (electro-luminescence) or CCFL (cold cathode fluorescent lamp). 
     Here, the foil will preferably have regions with and without microstructure. The foil will preferably be an almost transparent foil, capable of transmitting light, with a preferred thickness of 1 to 2 mm. Due to the transparency of the foil, the backlighting can pass almost unhindered through the regions of the foil which have no microstructure. The sections of the LC display covered by regions of the foil which has no microstructure can instead also be implemented with no foil, so that only those sections of the monochrome LC display which are to be marked in color are provided with a foil with microstructure. 
     Furthermore, the regions of the foil can have microstructures which are similar or different from one another. Here, several forms of implementation can be distinguished. For example, a first region might have exclusively a microstructure of one and the same type, and a second region exclusively a microstructure which differs from the first region. A conceivable alternative to this is one single region which is made up of different microstructures. The individual regions can be arranged to be separated by a gap or equally to be adjoining one another. 
     In addition, the regions will preferably have geometric boundaries. The boundaries of the regions of the foil which have a microstructure will then preferably correspond exactly to the geometries which are to be marked or highlighted, as applicable, by a different color from the backlighting. 
     Furthermore, each region can be individually illuminated, independently of other regions, in one or more colors. For this purpose, one or more LEDs are provided adjoining the regions. Preferably, use will be made of one single-colored LED or a RGB LED (red-green-blue LED) for each region. Several LEDs of different colors and several LEDs of the same color or the same type, as applicable, can also be provided for each region. The LEDs will preferably be arranged in such a way that their light is introduced from the side into the regions of the foil which have a microstructure. The LEDs could be arranged on one side or on different sides of the foil, whereby the alignment of the LEDs relative to the foil can be varied. The LED colors which could be used are, for example, red, green, blue and yellow. 
     The microstructure can in addition have surfaces for the purpose of reflecting the light from the LEDs. These surfaces can, for example, be arranged in such a way that the light on the surfaces from the LEDs is radiated away perpendicularly to the surface of the foil, towards the LC display. The light from the LEDs will thereby preferably be reflected only at these surfaces, perpendicularly to the foil surface or at some other predetermined angle to it. The size, shape and alignment of the surfaces, together with the number of them per region, can be varied depending, for example, on the level of the desired intensity of the colored highlighting, or on predefined viewing angles from which the display is to be recognizable. For example, in order to ensure that the information, in the form of texts and/or symbols, which is to be marked in color and which can be switched by a program, is recognizable over a range of viewing angles, the surfaces provided can also be dished or curved, for example in the form of hemispheres. 
     The operating and display unit in accordance with the invention will be used, in particular, in home appliances such as washing machines, dryers, dishwashers and cooking devices, in which the differentiated, switchable multi-colored backlighting highlights visually for the user certain program states and interactive program functions by the colored marking of texts or symbols. The use of the operating and display unit in accordance with the invention is not restricted to these application examples. 
     The principle of the invention is explained in more detail below by examples, by reference to figures in which 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         FIG. 1  shows a schematic diagram of an operating and display unit in accordance with the invention; 
         FIG. 2  shows a schematic diagram of a foil with microstructure regions; and 
         FIG. 3  shows an operating and display unit in accordance with the invention, with a display of different program functions. 
     
    
    
     DESCRIPTION OF THE INVENTION 
       FIG. 1  shows an operating and display unit  10  in accordance with the invention, with a monochrome LCD display  12  and a backlight  14 . A foil  16  is arranged between the LC display  12  and the backlight  14 . The foil  16  has regions  20 ,  22 ,  24  and  26  with a microstructure  18 . The microstructure  18  consists of a plurality of surfaces  28 . At the surfaces  28 , the colored light  40 ,  42 ,  44  and  46  introduced from the LEDs  30 ,  32 ,  34  and  36  arranged on the sides of the foil  16  is radiated away at an angle to the surface of the foil  16 , towards the LC display  12 . In this form of embodiment yellow light  42 , for example, is introduced into the region  22  of the foil  16  by the LED  32  in order to highlight in yellow the program-dependent lettering “Hot-coloreds” against the single color, for example white, of the backlight  14 . 
     In this form of embodiment, the regions  20 ,  22 ,  24  and  26  are defined by a right-angled geometry. With the form of embodiment shown in  FIG. 1 , red light  40  is introduced from the side into region  20  by the red LED  30 , yellow light  42  into region  22  by the yellow LED  32 , blue light  44  into region  24  by the blue LED  34  and green light  46  into region  26  by the green LED  36 . 
       FIG. 2  shows the foil  16  of the operating and display unit  10  already described in  FIG. 1 . Here, the regions  20 ,  22 ,  24  and  26  of the foil  16  which are provided with a microstructure  18  are shown with a right-angled geometry. In this form of embodiment, the microstructure  18  of the regions  20 ,  22 ,  24  and  26  has circle-shaped surfaces  28 . Also shown are the LEDs  30 ,  32 ,  34  and  36 , from which the colored light  40 ,  42 ,  44 , and  46  is introduced from the side into the corresponding regions  20 ,  22 ,  24  and  26 . The regions  38  of the foil  16  between the regions  20 ,  22 ,  24  and  26  do not have a microstructure  18 , and because of the transparency of the foil  16  they enable the light from the backlight to pass virtually unhindered through the foil  16  for the purpose of illuminating the LC display. 
       FIG. 3  shows an operating and display unit  10  in accordance with the invention, with five sections  50 . Here the texts, shown in the sections  50  by way of example, which can be switched according to the program, can be identified or highlighted in color. In this form of embodiment it is possible, for example, to highlight the lettering block: “Hot-coloreds 30° C.” in green, the lettering block: “Hot-coloreds 40° C.” in blue, the lettering block: “Hot-coloreds 60° C.” in yellow, and the lettering block: “Hot-coloreds 90° C.” in red against the single-colored white backlighting. The lettering block “Easycare 60° C.” and all the sections between the individual lettering blocks which can be highlighted in color, together with any bordering sections  48  which may be provided on the LC display, are backlit in a single color, for example white as in this form of embodiment, by the backlight. 
     Finally, it is noted once again that the operating and display units in accordance with the invention, described in detail above, are exemplary embodiments which a specialist can modify in a wide variety of ways without going outside the bounds of the invention. In particular, specific embodiments of the operating and display units can also take other forms from those described here. Such an operating and display unit can also be arranged in another form if space or design reasons make this necessary. Apart from this, for the sake of completeness attention is called to the fact that the use of the indefinite article “a” does not exclude the possibility of the characteristics concerned also being multiply present. 
     LIST OF REFERENCE MARKS 
     
         
           10  Operating and display unit 
           12  LC display 
           14  Backlight 
           16  Foil 
           18  Microstructure 
           20  Region of the foil with a microstructure 
           22  Region of the foil with a microstructure 
           24  Region of the foil with a microstructure 
           26  Region of the foil with a microstructure 
           28  Surfaces in the microstructure 
           30  Red LED 
           32  Yellow LED 
           34  Blue LED 
           36  Green LED 
           38  Region of the foil with no microstructure 
           40  Light (red) 
           42  Light (yellow) 
           44  Light (blue) 
           46  Light (green) 
           48  Border section of the LC display 
           50  Section of the LC display with no colored marking