Browse Prior Art Database

Light Baffles in Field-Emissive Displays

IP.com Disclosure Number: IPCOM000104852D
Original Publication Date: 1993-Jun-01
Included in the Prior Art Database: 2005-Mar-19
Document File: 2 page(s) / 58K

Publishing Venue

IBM

Related People

Beanlands, P: AUTHOR [+3]

Abstract

Described are physical improvements in the structure of Field-Emissive Display (FED) elements that maintain light output of prime pixels, while reducing unwanted illumination of adjacent pixels, so enhancing pixel contrast.

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This is the abbreviated version, containing approximately 64% of the total text.

Light Baffles in Field-Emissive Displays

      Described are physical improvements in the structure of
Field-Emissive Display (FED) elements that maintain light output of
prime pixels, while reducing unwanted illumination of adjacent
pixels, so enhancing pixel contrast.

      Referring to Fig. 1, Field-emissive displays use a large number
of micro-tip electron emitters 1 in a pixel 2, to emit cones of
electrons 3 across a 150-200um vacuum gap 4 to a phosphor screen 5,
as shown from one pixel P1.  Because the phosphor screen 5 runs at
just a few hundred volts, back surface metallization is not possible,
and light 6 generated by the phosphor is both transmitted to the user
and back into the display 7.  The gate structure 8 in FED displays is
highly reflecting - typically being made of niobium or aluminium -
and the light is reflected back to the phosphor, so that adjacent
pixels P2,P3,P4 are also illuminated, as shown in Fig. 1.  This
illumination of adjacent pixels is depicted in the bar chart (Fig.
2), and reduces the MTF of the display.  Design improvements proposed
to improve reduction of unwanted reflections are as follows.

1.    At the interstices of the cathodes, where a gap is left, light
    baffles 9 are deposited by a suitable process.  The baffles would
    be preferably non-reflecting.  Fig. 3 shows in simplified form
    that the light baffles 9 would reduce the unwanted illumination
    from pixels P2 and P3 to quite low levels. ...