High Performance Electrolummlscent Memory Display
Abstract
Thin film Electrolummlscent (EL) devices with memory are very attractive for panel displays with high information context. Practical development of EL memory displays have been hampered by problems of instability and reproducibility. Professor I. Solomon of the Ecole Polytechnique in Paliaseau, France, and Dr. P. Thioulouse of the nearby Centre National d'Etudes des Telecommunication (CNET) Laboratoire in Bagneux, proposed a new thin film structure in 1986 which overcomes these problems. Prototype displays have since been developed. In this device, a photoconducting (PC) thin film of amorphous silicon is added to the usual sandwich structure for EL displays. The memory effect results from the optical coupling between the PC thin film and EL active layer. In the off state, the PC layer is high impedance and thus the voltage drop across the EL layer is small. In the on state, the PC layer has a low impedance caused by the illumination from the EL film. The hysteretic switching of the PC film provides a memory effect which is controlled by the external bias. The PC film also improves the contrast ratio by providing a high impedance isolation of the EL film in the off state.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 07, 1989
- Accession Number
- ADA233606
Entities
Organizations
- Office of Naval Research