Field sequential color AMEL display

• US 5,986,628 A
• Filed: 05/14/1997
• Issued: 11/16/1999
• Est. Priority Date: 05/14/1997
• Status: Expired due to Term

• Current Assignee: Beneq Oy (Qingdao Sifang SRI & Intellectual Co., Ltd.)
• Original Assignee: Planar Systems Incorporated (Leyard Optoelectronic Co., Ltd.)
• Inventors: Wald, Steven, Larsson, Terrance, Tuenge, Richard, King, Christopher N.
• Primary Examiner(s): Hjerpe, Richard A.
• Assistant Examiner(s): Tran, Henry N.
• Application Number:
  US08/856,140
• Time in Patent Office: 916 Days
• Field of Search: 345/76, 345/65, 345/77, 345/80-84, 345/205, 345/213, 345/109, 345/88, 315/169.3, 340/757
• US Class Current: 345/76
• CPC Class Codes: G09G 2300/08 Active matrix structure, i.e. with use of active elements, inclusive of non-linear two terminal elements, in the pixels together with light emitting or modulating elements
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: G09G 3/30 using electroluminescent panels

Abstract

A full color active matrix electroluminescent display includes an active matrix of pixel electrodes, a broad spectrum electroluminescent phosphor stack placed atop the active matrix of pixel electrodes and a transparent electrode placed atop the electroluminescent phosphor stack. A liquid crystal color shutter device is placed atop the transparent electrode for selectively filtering light from the electroluminescent phosphor stack selectively permitting the transmission of red, green or blue colored light in response to commands from a synchronizing circuit that synchronizes the operation of the shutter with the illumination of selected pixels in the active matrix display. Performance is further enhanced by the use of a double notch filter for the white light emitting broad spectrum electroluminescent phosphor so as to provide it with a uniform response at all waves lengths of interest.

Claims

1. A full color active matrix electroluminescent display comprising:

a) a matrix of active thin film electroluminescent (TFEL) pixel electrodes;

b) a broad band white light emitting phosphor material placed atop the matrix of active TFEL pixel electrodes;

c) a transparent electrode placed atop the phosphor material;

d) a liquid crystal color shutter device having at least three logic states for transmitting selected primary colors during three subframes of video; and

e) a synchronizing circuit for synchronizing the energization of selected pixel electrodes in said matrix with said liquid crystal color shutter device to produce frames of video at a predetermined frame repetition rate, each frame of video comprising three subframes of video wherein during a first subframe of video red light is transmitted, during a second subframe of video green light is transmitted and during a third subframe of video blue light is transmitted.

2. The full color active matrix TFEL display of claim 1 further including a notch filter having at least one notch at a wave length of high intensity light emission produced by the broad band white light emitting phosphor material so as to provide a substantially flat profile of the frequency spectrum of light emitted by the white light emitting phosphor.

3. The full color active matrix TFEL of claim 2 wherein said phosphor material is ZnS:

Mn/SrS;

Ce and said notch filter has a notch at each one of a pair of wavelengths of high intensity light emission from said phosphor material.