A medical device such as a catheter or endoscope device includes an illumination light source having one or more organic light-emitting diodes (OLEDs). The OLEDs are energized to produce illumination light that is received by an image sensor or camera to produce images of tissue within a patient's body....http://www.google.de/patents/US20050137459?utm_source=gb-gplus-sharePatent US20050137459 - Medical device with OLED illumination light source
