Voltage level indicator

Abstract

Integrated voltage level indicator comprising a plurality of polymer LEDs between two contact leads, in which the number of luminescing LEDs and/or the intensity of the light in each LED is determined by the external voltage level.

1 . A display device comprising a plurality of electroluminescent diodes and means for causing one or more of the diodes to luminesce in dependence upon a voltage to be supplied between two connection points, characterized in that at least the electroluminescent diodes are integrated in one semiconductor body.  
     
     
         2 . A display device as claimed in  claim 1 , characterized in that the electroluminescent diodes comprise a layer of electroluminescent material with a common active layer of an organic material, which layer is present between a first and a second pattern of electrodes, at least one of the two patterns being transparent to light to be emitted by the active layer, and the first pattern comprising a material which is suitable for injecting charge carriers.  
     
     
         3 . A display device as claimed in  claim 1 , characterized in that the electroluminescent diodes are arranged in parallel branches and are provided with mutually different series resistors in the parallel branches.  
     
     
         4 . A display device as claimed in  claim 3 , characterized in that said display device comprises parallel resistors arranged parallel to the electroluminescent diodes in the parallel branches.  
     
     
         5 . A display device as claimed in  claim 3 , characterized in that the electroluminescent diodes are provided with mutually different series resistors, and the parallel branches are arranged between a common point and connections to a voltage divider.  
     
     
         6 . A display device as claimed in  claim 5 , characterized in that the voltage divider comprises resistors.  
     
     
         7 . A display device as claimed in  claim 3 , characterized in that the display device comprises a voltage-controlled oscillator arranged between a connection point and the part of the parallel branches which is common for the series resistors.  
     
     
         8 . A display device as claimed in  claim 3  or  6 , characterized in that series resistors or resistors are integrated in the semiconductor body.  
     
     
         9 . A display device as claimed in  claim 3 , characterized in that the display device comprises a diode having a steeper current/voltage characteristic than the electroluminescent diodes, which diode is arranged between a connection point and the part of the parallel branches which is common for the series resistors.  
     
     
         10 . A display device as claimed in  claim 8 , characterized in that the display device comprises an optical filter.