Liquid crystal display device with optoelectronic component and method for controlling backlighting of such a display device

#This application is a continuation of copending International Application No. PCT/DE01/00772 filed Nov. 21, 2000, which designates the United States.

#The invention concerns an LC display with at least one optoelectronic component and a light source for backlighting of the display, as well as the method for controlling backlighting.

#Control of backlighting in LC displays that have backlighting can occur as a function of the surrounding brightness. This is particularly advantageous in battery-operated equipment or portable equipment equipped with batteries, since the energy consumption of backlighting is very high. In order to permit expedient control of backlighting, a light sensor, generally a photodiode, must, if possible, accurately measure the light intensity of the surrounding light falling on the display. Suitable arrangement of the sensor is problematical precisely in small devices. In particular, unintended shading, for example, by the hands of the user, must be avoided. Similar problems occur in infrared sensors for receiving signals of an electronic device (for example, remote control), which are often also arranged in the vicinity of the display.

#Additional advantages, features and application possibilities of the invention are apparent from the description of practical examples in conjunction with the drawings. In the drawing:

#FIG. 1 shows a section through a transflective LC display with a light guide and reflector,

#FIG. 2 shows a view of the light guide of FIG. 1, in which possible positions for an optoelectronic component are shown,

#FIG. 1 shows a simple transflective LC display that reflects daylight or surrounding light and is additionally provided with backlighting. It has a front and rear pole filter 1, between which two parallel glass substrates 2 are arranged. A liquid crystal layer 10 is embedded between two glass substrates 2. The glass substrates 2 are connected to each other via a joining frame. The joining frame prevents emergence of the liquid crystal.

#A light guide 4 is arranged on the rear pole filter 1 of the display. The light guide 4 is therefore situated on the backside or side 9 (backside) of the display facing away from a viewer. Light for backlighting of the display is coupled into the fiber-optic light guide 4 from a light source 5, just as incoming surrounding light is reflected in the direction of the viewer. For this purpose, the fiber-optic light guide 4 is provided with a reflector 11 on the side facing away from the glass substrate. The light source 5 is arranged parallel to the glass substrate 2 and emits light only of one part of the visible spectrum. Advantageously, it is a light source that furnishes monochromatic light.

#An optoelectronic component 6 is arranged on one side of the fiber-optic light guide 4, which is aligned perpendicular to the glass substrate 2. The component 6 is aligned in an axis that essentially coincides with the radiation axis of light source 5. Component 6 is arranged in a plane parallel to the rear pole filter 1 and farther removed from the front pole filter than from the rear pole filter. A phototransistor, which can be used as a transmitter and/or receiver, a photodiode or another means of light measurement (CCD), is considered as optoelectronic component 6. Component 6 in this practical example is a photodiode that serves as sensor.