Liquid crystal indicator, preferably for motor vehicles

Details Liquid crystal indicator, preferably for motor vehicles Liquid crystal indicator, preferably for motor vehicles

1989-04-21

1991-11-05

Brier, Jeffery A.

Communications: electrical

Land vehicle alarms or indicators

Internal alarm or indicator responsive to a condition of the...

340702, 3408151, 359103, G09G 336

Patent

active

050633791

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention relates to a display device preferably for motor vehicles for measured values, trouble indications and the like comprising at least one liquid crystal cell, illuminated from the rear to have areas with different colorations of letters, symbols, or indications illuminated.
In a known display device of this type, areas of the liquid crystal cell with various coloring of the letters and symbols and the data to be displayed, respectively, are provided by color foils which are inserted between the liquid crystal cell and a transflector arranged behind the latter, so that a good coloration is achieved in bright ambient light as well as in darkness (Elektronik, 1983, 19, page 16). In addition, it is also known to arrange a corresponding color imprint on the back of the LCD in the areas with different coloration when using transmissive LCDs. This is particularly desirable in large liquid crystal displays in motor vehicles where warning or trouble indications are to be emphasized over other indications, such as time, velocity, engine speed and the like, by different colors.
However, a disadvantage in the known solutions is that each area of the LCD can only have one color assigned to it. If different colors are desired in the various areas of the LCD, in each instance, in different types of vehicles it is necessary to have available a corresponding wide assortment of liquid crystal cells, which requires a considerable expenditure on storage. It is also disadvantageous that the different coloring produced by foils or color printing also affects the blocked areas of the LCD which are not being controlled, so that an unwanted background brightness varying in color and intensity results in these areas.


SUMMARY OF THE INVENTION

The object of the present invention is to make it possible to freely select a different coloring in different areas of the LCD at any time so as to provide complete flexibility for the selection of the coloration with limited storage.
This object is achieved in the display device, according to the invention, by providing at least one light guide at the rear side of an area so that the areas of the LCD with different coloring can be delimited relative to one another and can be illuminated by variously colored light sources. The desired coloring can be freely chosen, since the desired coloring is effected only after the assembly of the display device with the insertion of the light sources in the individual areas of the LCD. Another advantage consists in that a uniform background brightness is made possible in the blocked areas of the LCD by known measures, such as e.g., the arrangement of scattering foils and fluorescent plates, screen print and the like, and in that a uniform transmission of light in the controlled surface area segments of the LCD is achieved. The transition of colors between the areas of different coloration can be made so smooth in this way that a very good visual appearance results accordingly.
It is particularly advantageous to arrange a plurality of light sources of different colors at the rear end area of the light guide in order to enable a change of color in an area of the LCD by switching the bulbs. Accordingly, it is possible, in addition, to provide a bulb with white light for a uniform background brightness of the LCD. If, for example, the area is provided in the vehicle for function and status indications of various devices, it is advantageous to switch on a green light for displaying normal values and functions. In contrast, a red light is switched on for this area of the LCD when displaying disturbances, wherein the trouble indication is distinguished on the LCD e.g. by intermittent illumination of the problem function.
Moreover, the use of light guides for illuminating the LCD has the advantage that the light sources can be arranged laterally next to, behind or outside the display device, so that the space requirement for the illumination of the LCD is very small and the construction design of the display device is acc

REFERENCES:
patent: 4714983 (1987-12-01), Lang
patent: 4965564 (1990-10-01), Fabry et al.

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