A solid-state image-storage panel based on field-effect conductivity control

A solid-state display panel has been developed capable of converting a transient optical image into a stored luminescent image. Such panels are two-layer devices, employing a special photoconductively controlled field-effect layer for the input and a conventional type of powder-binder electroluminescent layer for the output. Image storage times of the order of an hour may be obtained or the image can be electrically erased in a second or less when desired, leaving the panel ready for the acceptance of a new image. Erasing may also be accomplished gradually to produce a controlled persistence or selective areas of the image may be erased. In addition to its long storage time, the output image contains good halftones and has high contrast. Since the image brightness is as high as 20-foot lamberts, the panel may be viewed in moderate room illumination. Because of the relative transparency of the control layer the stored image may be viewed with approximately equal brightness from both sides of the panel. In present panels optical feedback is prevented by employing a green-emitting electroluminescent layer whose spectral emission is of longer wavelength than the radiation to which the control layer is responsive. Panels have been fabricated in sizes up to and are capable of displaying image details 0.020" or smaller.