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Patent 2196040 Summary

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(12) Patent Application: (11) CA 2196040
(54) English Title: FLAT DISPLAY SPACER STRUCTURE AND MANUFACTURING METHOD
(54) French Title: ELEMENTS D'ESPACEMENT POUR DISPOSITIF D'AFFICHAGE PLAT, ET PROCEDE DE FABRICATION
Status: Dead
Bibliographic Data
(51) International Patent Classification (IPC):
  • H01J 5/48 (2006.01)
  • H01J 29/02 (2006.01)
  • H01J 63/02 (2006.01)
(72) Inventors :
  • JONES, GARY W. (United States of America)
  • ZIMMERMAN, STEVEN M. (United States of America)
(73) Owners :
  • JONES, GARY W. (Not Available)
  • ZIMMERMAN, STEVEN M. (Not Available)
(71) Applicants :
  • FED CORPORATION (United States of America)
(74) Agent: KIRBY EADES GALE BAKER
(74) Associate agent:
(45) Issued:
(86) PCT Filing Date: 1995-07-25
(87) Open to Public Inspection: 1996-02-08
Availability of licence: N/A
(25) Language of filing: English

Patent Cooperation Treaty (PCT): Yes
(86) PCT Filing Number: PCT/US1995/010028
(87) International Publication Number: WO1996/003764
(85) National Entry: 1997-01-27

(30) Application Priority Data:
Application No. Country/Territory Date
280,355 United States of America 1994-07-25

Abstracts

English Abstract




A spacer structure (10) for use in a flat panel display (100), and a
corresponding flat panel display article (100) are disclosed, together with an
appertaining method of fabricating the spacer structure utilizing a
photosensitive precursor material which is selectively irradiated, developed
and etchingly processed to produce shaped standoff elements for a unitary
spacer structure. The spacer structure may be dimensionally fabricated to
precisely align with a selected pixel region, comprising a single pixel or an
array of pixels, e.g., a color (red, blue, green) triad.


French Abstract

L'invention concerne une plaque à éléments d'espacement (10) prévue pour être utilisée dans un dispositif d'affichage à panneau plat (100), et un dispositif d'affichage à panneau plat (100). L'invention a également pour objet un procédé de fabrication de cette plaque utilisant un matériau précurseur photosensible qui est irradié, développé et traité par attaque chimique, de manière sélective, pour produire des éléments de séparation mis en forme pour obtenir une plaque à éléments d'espacement. Cette plaque peut être fabriquée, de manière dimensionnelle, pour s'aligner avec précision avec une zone d'éléments d'images sélectionnée, comprenant un seul élément d'image ou un ensemble d'éléments d'images, par exemple, un triplet de luminophores (rouge, bleu, vert).

Claims

Note: Claims are shown in the official language in which they were submitted.


17
THE CLAIMS
What Is Claimed is:
1. A display panel comprising:
an anode plate;
an electron source plate comprising an array of field emitter elements; and

spacing means for maintaining said anode plate and electron source plate
in spaced relationship to one another said spacing means comprising a planar
matrix support structure of intersecting elongate members which define a plurality
of individual cells therebetween, said matrix support structure being formed as a
unitary spacer structure having photoformed spacer elements integrally joined
perpendicularly to the planar support structure at points of intersection of theintersecting elongate members and interposed in bearing and supporting
relationship between said anode and electron source plates said individual cellsdefining pixel regions of the display panel.

2. A display panel according to claim 1, wherein said photoformed spacer
elements are arranged at each of said points of intersection of the intersectingelongate members to circumscribingly bound each of the individual cells.

3. A display panel according to claim 1 wherein each of the pixel regions
comprises a single pixel.

4. A display panel according to claim 2 wherein each of the pixel regions
comprises an array of pixels.

5. A display panel according to claim 1 wherein the intersecting elongate
members are perpendicularly arranged forming a grid-structure having the spacer
elements joined at the intersections thereof.

6. A display panel according to claim 5 wherein the spacer elements in said
spacer structure comprise columnar elements extending upwardly from the
grid-structure.

18
7. A display panel according to claim 1, wherein the intersecting elongate
members and photoformed spacer elements of said spacing means are formed,
developed, and etched from a unitary block of photoformable material to yield a
support grid structure having said spacer elements which bound openings which
define the pixel regions for throughput of electrons from the electron source plate
through the spacing means to the anode plate.

8. A display panel according to claim 1, wherein the unitary spacer structure isformed of a developed and etched glass material comprising said photoformed
spacer elements.

9. A display panel according to claim 1, wherein the anode plate comprises an
anode plate substrate metalized with a reflective/conductive metal anode layer of
patterned character defining non-metalized openings surrounded by metalized
regions of the metalized anode layer, wherein the spacer elements are aligned
with the non-metalized openings in the metalized anode layer.

10. A method of making a display panel comprising an anode plate, an electron
source plate including an array of field emitter elements, and a spacer structure
including a plurality of spacer elements, interposed between said anode and
electron source plates, comprising the steps of:

providing a photosensitive material workpiece as a precursor structure of at least
a portion of said spacer structure comprising said spacer elements;

exposing a surface of said photosensitive material workpiece to
photosensitizingly effective radiation for sufficient time and at sufficient intensity to
photosensitize selected portions of the photosensitive material workpiece;

removing non-photoexposed material from said workpiece to yield at least a
portion of said spacer structure including a plurality of spacer elements, and
forming the spacer structure to comprise a planar matrix support structure of
intersecting elongate members, which define a plurality of individual cells
therebetween, as a unitary spacer structure having photoformed spacer elements
integrally joined perpendicularly to the planar support structure at points of
intersection of the intersecting elongate members; and

19A

interposing the spacer structure between said anode and electron source plates,
such that the anode and electron source plates are maintained in spaced-apart
relationship to one another by said spacer structures and so that the individualcells define pixel regions of the display panel.

11. A method according to claim 10, wherein the array of field emitter elements
and said anode plate define a multiplicity of pixels, and wherein the photoformed
spacer elements circumscribingly bound a predetermined pixel region.

12. A method according to claim 11, wherein the pixel region comprises a pixel
array.

13. A method according to claim 11, wherein the pixel region comprises a single
pixel.

14. A method according to claim 10, wherein the spacer structure comprises a
support matrix of perpendicularly arranged arrays of elements forming a grid
structure having the spacer elements joined thereto.

15. A method according to claim 14, wherein the spacer elements in said spacer
structure comprise columnar elements extending upwardly from the grid structure.
16. A method according to claim 10, wherein the spacer structure is formed,
developed, and etched from a unitary block of photoformable material to yield a
support grid structure having said spacer elements which bound openings which
define the pixel regions for throughput of electrons from the electron source plate
through the spacing means to the anode plate.

17. A method according to claim 10, wherein the spacer structure is formed of a
developed and etched glass material comprising said photoformed spacer
elements.

18. A method according to claim 10, wherein the anode plate comprises an
anode plate substrate metalized with a reflective/conductive metal anode layer of
patterned character defining non-metalized openings surrounded by metalized
regions of the metalized anode layer, and wherein the spacer elements are
aligned with the non-metalized openings in the metalized anode layer.

19B

19. A display panel comprising:
an anode plate;
an electron source plate comprising an array of field emitter elements; and

spacing means for maintaining said anode plate and electron source plate
in spaced relationship to one another, said spacing means comprising a planar
matrix support structure of intersecting elongate members, which define a plurality
of individual cells therebetween, said matrix support structure being formed as a
unitary spacer structure having spacer elements integrally mounted to and
extending perpendicularly from the planar support structure at points of
intersection of the intersecting elongate members and interposed in bearing andsupporting relationship between said anode and electron source plates, said
individual cells defining pixel regions of the display screen, and wherein said
spacer elements have been formed of photoreactive material which has been
selectively shaped by preferential etching of the material and coated with an
insulative layer for charge leakage control.

Description

Note: Descriptions are shown in the official language in which they were submitted.


W0 96/03764 1 ~ u.,,~
21 96040
~ 1

--FLAT DISPLAY SPACER STRUCTURE AND MANUFACTURING METHOD--


DESCRIPTION
Fleld of the l"~_..llon
This invention relates generally to flat panel displays coll~ aillg spaced-apartanode and field emitter plates, and more particularly to a flat panel display
assembly of such type utilizing novel spacer means.

De~ n of the Related Art

In the use of field emitter l~chl)ology, a wide variety of flat panel display
asse,",'" have been proposed by the prior art. In general, these display
ass~",' ' comprise spaced-apart cathode (emitter) and anode plates, wherein
the emitter plate comprises a multiplicity of field emission elements which produce
electron beams which are lldll~,,,iLL~d to the anode display plate, which may for
example comprise an array of phosphor elements or other lu",i"es~,~"l materials
or members, which are lull,i,lesc~,ltly responsive to the i,,,,ui,,ge,,,e,,L of electrons
thereon.

In the manufacturing of flat panel display asst:" ' " of the above-discussed type,
the respective emitter and anode plates must be readily fabricated in spaced-
apart ,~ldlional,;~. to one another, and a variety of spacer means and methods
have been proposed in the prior art to effectuate the required spaced-structuralIt:ldliollsl,i~- between the plates.

More ~- ~r- lly, the spacer structure is a critical element in the development of
large-area reduced-pressure flat panel displays, which is a practical obstacle to
the convergence of other aspects of display It:~:hl lology, such as emitter sources
and pho:,,ullu,:,. The use of displays in a wide spectrum of ,, ' ' ls, including
defense, scientific, medical, educational, business and r~ dliondl usages, has
pl~ ,.dltld, and yet the potential for additional:,, ' " ,s and l~fi"t:",~"l in the
conventional It:~,hllulogy is substantial. With the p,.' ~ dliun of devices such as
portable work stations, lap tops, palm tops, pen-based pads, video phones,
cellular phones, digital high definition television (HDTV), etc., and the prulilt1rdlion

WO 96/03764 2 1 9 6 0 4 0 PCT/US95/10028


of world-wide multimedia networks and satellite direct access --r '"" 1~ the
volume of available cyberspace ill~ulllldliull is aldu5Jelillg in amount, and the
visual display appears to be the only device which is effectively poised to
communicate in a quick and efficient manner the vast amount of available
illrullllaLiull to users thereof.

Concerning specific ", " l areas of flat panel displays, ~ ' ls such asportable equipment and miniaturized ,,,i..ruele.,llu,,ic devices require extremely
small volume to viewing area ratios, which more generally are desirable in a wide
variety of othem,, ' la. Lap top, notebook and pen-based computer devices
require flat panel displays to constitute cu"""~,..ial'y viable devices. The current
promise of digital HDTV may never be realized in many households if it demands
space for a 10û cubic foot cathode ray tube (CRT) or rear-projection based
monitor. A truly functional and affordable flat panel display le..h,loloyy is likely to
displace virtually every other form of two-di",el)siollal display, including those
used in stereo pair gent" 1 for 3-D viewing.

Despite its promise, many ~ u~ ~c l~,,ll"oloyias including liquid crystal
displays (LCD's), active matrix liquid crystal displays (AMLCD's), plasma displays,
electrolu",i"esce"l displays and vacuum fluorescent displays have been utilized
as coll""el.;idl alternatives to flat panels, but all of these " u.ltk/c displaydevices fall far short of providing an optimum flat panel illl~ lllelltdliuil. Major
issues such as cost, power efficiency, viewing angle, briul,tl,esa, and color purity
diminish their utility, non t~lhele55, the demand for flat panel functionality is
sufficiently great so that such serious limitations currently not only are tolerated,
but su~-recRf~llly compete with traditional display Lt:~.l),lology.

Field emitter array (FEA) displays provide a new display l~.hnology that is at least
Ll,eo~ .al'y capable of meeting all of the requirements for a general purpose flat
panel display. Advantages of FL--A display l~ull~uloyy include thinness of the
panel (no bulky CRT tube and yoke, or back light, is required), low weight
ullala~ liatics, wide viewing angle capability, wide range of color viewing
capacity, high efficiency (direct light yelleldlioll~ cold cathode electron source
means), high b,i~hl,leaa, high resolution, very fast response time, wide dynamicrange ffrom night levels to direct sunlight visibility), wide l~ ,uel Ire range
operating capability, instant turn-on character, back site co,,,,uune,,l mounting
ability, and reduced cost (being less expensive and much simpler in structure
than the AMLCD).

2~1 96040
WO 96103764 PCTIUS95/10028

~ 3

Although the art has directed col,aide,dble effort to basic structures, materials,
and manufacturing p~ucesses necessary to produce emitters for display purposes,
unfortunately the critical spacer structure has not received a significant amount of
attention.

Display structures using field emitters require a sufficient distance between the
emitter (cathode) and the phosphor plate (anode) to isolate high anode voltages
used to achieve the most efflcient excitation of the light-gene,dLi"g phosphOIa.Spacing dil,lerlaiu"a on the order of from about û.5 mm to about 1.5 mm are
typical. These spacing .li",el,sior,s, while seemingly small, are in fact very large
compared to the mean free path of electrons in dLIIIua~ ulic pressure gases
between the respective cathode and anode plates. As a result, the spacing
between plates must be evacuated to the pressure levels found in typical CRT's.
Other flat panel display L~-,lllloloyies also require partial (plasma displays) or
co",yd,dL,le (vacuum fluorescent displays) levels of evacuation. Evacuation of
the space between the cathode and anode plates places a one dLIII0afJIl~l~ (760
mm) static load on the plates and produces a plate deflection that is d~.endel,L o
the area, strength and thickness of the material of construction of the plate,
typically glass. Excessive deflection may seriously adversely affect the operating
ulldla.~L~IibLk,a of the flat panel display, in such respects as pixel size, uniformity of
L,iyl,L"es:" and may increase the risk of anode to grid or cathode arcing. For
small displays, such deflection is not a problem of significant character, due to the
di~ .iulls involved. Typical glass Ll,i.:hl,esses of 2-3 mm may be used in
perimeter-supported displays of up to 50 mm and potentially higher dilll~llaiOIls,
but for larger area display articles, the corlt:a,uondillg need to increase plate
thickness to acco"""o.ldL~ such pressure levels would suuaLd,,'i~ add to the
thickness and weight ulldld~iLt:liaLius of the overall display and is not conside,esd
P~cepb ~IP or desirable for collllllt:ll,idl and aesthetic reasons. Accordingly, for
larger area displays, internal spacer means are necessary to prevent undue
deflection with the consequent adverse effects on operability, it being l~coy"i~t:d
that excessive pressure deflection in the absence of suitable spacer (support)
means in the interior volume of the flat panel display article may result in rupturing
of the evacuated plate and loss of its utility for its intended purpose.

The plate spacer structure introduces a number of structural and design
cu~,ul~iLies to the ~dbliCdLiUn of the flat panel display article. The spacer
stnucture must be strong enough to support the static pressure load, as well as

WO 96/03764 2 1 9 6 0 4 0 PcrluS9~l10028


any additional dynamic load resulting from handling, assembly, and use of the
display. Further, the spacer structure must be fabricated to fit between pixels or
pixel arrays (e.g., triads of color sub-pixels). The spacer structure further must
stand off (insulate) the high anode potential. The spacer structure additionallymust provide a continuous open pathway parallel to the plates to allow both initial
evacuation of the display panel article, and long-term gettering of slowly released
gas cu~ llilldl~ts (off-gassing in situ in the interior volume of the display panel).

From a design sLdlldlJoilll, the spacer structure must permit alignment to the
emitter (cathode) pixel structures, as well as to the anode plates phosphor color
patterns in color display articles. The spacer structure must also be cost-effective
in ~dbliCdLiOn and assembly.

The foregoing requirements present a great challenge in the development of
conllller~.i..lly Arre},~ le, mass-producible flat panel display articles that are field
emitter-based, and provide medium to large area display capability.

Currently practiced spacing means and methods have r--- ' ' 3C' severe
:.hulL..u~ , One fleld emitter display article prototype devised by LETI in
France, utilizes glass spheres which are adhered to the emitter plates with a
screened-on organic adhesive medium. The spherical spacer elements are
ulldesildule because their aspect ratio (1:1) do not satisfy the requirements ofhigher resolution displays and their shape increases the potential for arcing
between the anode and the grid or emitters. Organic adhesives also are
u~desildule because of the ~c~O~ d high temperature sealing con" ~.,s
required, evacuation bake requirements during pump-out, long-term outgassing
loads in the small volume static vacuum space, and because the low dielectric
constant of the organic adhesive at the interface promotes splash-over.

The use of cured phuLusen ~c polyimide spacer blocks formed directly on the
emitter plate from 100 ~;.,Iu~ ,.-thick films has been proposed. This technique
also is severely limited in aspect ratio l.ihdldULeli Lil ::- and long-term outgassing
properties of the polyimide material in small high vacuum as~e",' ' has not
been de" ,u"~L, dled .

Other plasma dispiays have been produced using tall, velLi~.ally standing metal
wire segment spacers. The insulated AC operation of these panels allows the
use of these metal spacers which are individually placed on an adhesive material,



, . , _ _ _ _ _ _ == . . . . _ _ ... _ _ . _ .

WO 96/03764 2 ~ 9 6 0 4 0 PCT/US95/10028

~ 5
in a standing position but they are u"~ for field emitter displays. The
Illaill~.ndllce of spacers in a precise vertical position during the fabricationoperation is a difficult and yield-limiting task. Although collld~ ldliull is less of a
problem in plasma display ~F ~s which work in a moderate pressure gas
environment, the colltcllllilldliun ;.~ oc;~l~d with the use of such adhesive material
with the metal spacers is highly ~",deai,dule in field emitter-based panel article
'15.

Accordingly none of the d~u,~",t:"Liol,ed conventional spacer techniques satisfies
the req~ ",~"t~ of high pe,ru""d"~.e vacuum panel displays.

It therefore is an object of the present invention to provide a means and method of
spacing emitter and anode plates in a field emitter-based flat panel display
assembly, which overcomes the L'u,~",~"t;oned various disadvantages of the
prior art spacer means and methods.

it is another object of the present invention to provide such improved spacer
means and method which are effectively utilized in large area display panel
~i~ ns.

It is a further object of the present invention to provide such improved spacer
means and method which are non-deleterious to the pixel a"d"~",~"l and
operation of the display panel.

Other objects and advantages of the present invention will be more fully apparent
from the ensuing disclosure and appended claims.

~RY OF THE INVENTION
In one aspect, the present invention relates to a display panel cu~utiai~g an
anode plate, an electron source plate co",,u,i:,i"g an array of field emitter
elements defining with the anode plate pixels of the display panel, with the anode
plate and electron source plate being ",c.i"td;"ed in spaced l~ldlioll:~hiu to one
another by spacing means co~ JIiaillg a unitary spacer structure cor"urisi"g
pllutufv~ ed spacer elements joined to a support structure and i" uosed in
bearing and supporting ~tlldliullshiu between said anode and electron source
plates. As used herein, the term ul,utulu"" means that a material is formed by

WO 96/03764 2 1 9 6 0 4 0 PCTNS9S/10028


irradiation of a precursor workpiece and then processed to form a structural
member or cu",uone"t.

The pl,uLuru,~,,ed spacer elements preferably are constructed and arranged in
arrays to circu" lacliLJil Iyly bound a pixel region, e.g., cu",~u, iail ,9 a single pixel, or
an array of pixels.

The spacer structure may suitably comprise a support matrix of perpendicularly
arranged arrays of elements forming a grid-structure having the spacer elements
joined thereto.

Preferably, the spacer elements in the spacer structure comprise columnar
elements extending upwardly from the grid support structure.

The unitary spacer structure advantageously is formed, developed, and etched to
yield an array of vertically upwardly extending spacer elements extending from
and integral with a support grid structure having the spacer elements arranged to
bound openings ac-;or"",ocklli"g pu:~it;urlillg in relation to pixel regions forthroughput of electrons from the electron source plate through the spacer
structure to the anode plate.

The unitary spacer structure for example may be formed of a developed and
etched glass material co,,,,u,i:,i,,g the ,chutufulllled spacer elements.

Co,,t~polldi,,~u,ly, the anode plate may comprise an anode plate substrate
metalized with a reflective/conductive metal anode layer of patterned character
defining non-metalized openings surrounded by metalized regions of the
metalized anode layer, wherein the spacer elements are aligned with the non-
metalized openings in the metalized anode layer.

In another aspect, the present invention relates to a method of making a displaypanel cu~,uliai''g an anode plate, an electron source plate including an array of
field emitter elements, and a spacer structure including a plurality of spacer
elements, i"lt:"uosed between the anode and electron source plates, cor",uriai"ythe steps of:

providing a pllutuae"aili"e material workpiece as a precursor structure of at least
a portion of the spacer structure culll,uliainy the spacer elements;



,, , . ... .. = . _ . _ . . , , _

WO 96/03764 2 1 9 6 0 4 0 PCT/US95/lOOU

~ 7

exposing a surface of the phulusenailive material workpiece to phuLusellaili~ lyeffective radiation for sufficient time and at sufficient intensity to phulosenaili~e
selected portions of the phutùst:,,ailive material ~.J,hpi~ce,

removing non-ph.~ ,osed material from said workpiece to yield at least a
portion of the spacer structure including a plurality of spacer elements; and

osi"g the spacer structure between the anode and electron source plates,
such that the anode and electron source plates are ",d;"ld;"ed in spaced-apart
liu~ lahi~J to one another by the spacer structure.

Other aspects, features, and e",bodi",e"ta of the invention will be more fully
apparent from the ensuing disclosure and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a top plan view of a spacer structure according to one e",bo.li",t:"l of
the present invention.

Figure 2 is a front elevation view of the Figure 1 spacer structure.

Figure 3 is a bottom plan view of the spacer structure of Fj9UrQ 1.

Flgure 4 is a top plan view of a portion of a field emitter flat panel display
assembly, ~,or"~.,iai"a a spacer structure according to one ~",bodi",el,l of thepresent invention, of the type shown in Figure 1, shown superposed on a field
emitter color triad array.

Figure 5 is a pe,a~.e~ c view of a flat panel display assembly according to one
c:"lbodi"~e"l of the present invention, and featuring spacer structure in
au~o,.ld"ce with the invention in an exemplary e:lllbOdi~ lll thereof.

~ Figure 6 is a sectional elevation view of a portion of a flat panel display
assembly according to Figure 5, showing the Culll,udllc~llL structure thereof
including the emitter and anode plates and spacer structure.

WO 96/0376~ 2 1 9 6 0 4 0 PCT/US95/10028


Figure 7 is a schematic illustration of a process system for photo developing a
plluluaellaiIi\le material to form a conical mask region in a substrate.

Figure 8 is a schematic depiction of the conical element formed from the
irradiated substrate shown in Figure 7 subsequent to etch removal of
phul ~g.osed portions of the substrate.

Figure 9 is a schematic illustration of a process system for irradiating a
plluluse~siIi~/e substrate to produce a masked inverted fn,aluco,,iL.c,l region.
Figure 10 is a s- I~c~"~aIic depiction of an inverted fru~tucu"i.al structural element
formed by etch removal of irradiated portions of the substrate of Figure 9.

DET~ Fn l:~ESCRIPTION OF THE INVFNTION . AND PREFERRFn
~a~ODlMFNTS THEREOF

The present invention utilizes pllutusellaili~/e materials such as glasses polymers,
etc. that can be irradiated, thermally developed and ,he",ica:j etched into
complex patterns. The phulus~siIive material may for example comprise a
phutusel,sili~/e glass ceramic glass-ceramic material or polymeric material of
suitable character. Advantageous glass and ceramic (glass-ceramic) materials
suitable for usage include the materials co"""~ y available from Corning Inc.
under the I,~de",~,ks ~ FORM~ and FOTOCERAM~. A particuiarly preferred
illustrative material of such type is Fvtulullll~) UV-sensitive glass (Corning Inc.
Corning NY). Such material can provide aspect ratios of up to 4û:1 (aspect ratios
as used herein referring to the length or longitudinal dimension of a structure
relative to its width or transverse di",el1~iun)~ as well as high quality insulating
properties and a."en ~y to forming multilevel structures allowing transverse
pathways. Although such materials have inherent potential . ' ~ 'i 1 to use in
spacer structures the prior art has not seriously cùllaklelt:d same for flat panel
display l~u~ic.lt;on because of their excessive cost and limited size (for example
the ~lu,~",~"lioned Fotoform glass is currently available only in 7 x 7 inch
maximum sizes.

Accordingly the present invention utilizes such radiation-alterable materials in a
novel spacer structure which beneficially utilizes the desirable aspects of

WO 96/03764 2 1 9 6 0 4 0 PCTIUS95110028
.~ 9

materials such as the d~u,~",e"Lioned phulu~u,,,,~ble glass materials, while
overcoming their limitations of size and cost.

Accordingly, in a preferred aspect, the present invention cûlltulll,uldl~s the use of
relatively small, discreet spacer members, such as is shown in Figure 1.

Figure 1 is a top plan view of a spacer structure 10 in which such spacer
member cu",,ur;aes a regular array of standoffs 12, which are vertically upwardly
extending elements having upper bearing services 20 for abutting supportive
contact with a plate member of a display panel, or such contact with a
cc."t::"uondi.,9 opposedly facing spacer structure (i.e., wherein respective facing
spacer structures are mated in abutted contact with one another, with for example,
one spacer structure being r--- ~ ~ ' with the emitter (cathode) plate of the
display panel, and the other spacer structure being ~ ' 3C' with the anode
plate of the display article).

The standoffs 12 in this e,,lLu-li,,lt:lll are of truncated pyramidal shape. It will be
It:uoylli~t:d that the standoff elements of the support structure may be of any
suitable shape or geometry, as necessary or desirable in a given end use
~FF'- - 1.

The standoff elements 20 are i" -uu, " ,eulud in a matrix structure by means of the
horizontal support members 14 and the vertical support members 16 (such
horizontal and vertical directions referring to the O~ utdt;ull of the spacer structure
as shown in Figure 1, it being It:coyll;~:d that the shape of these members and
their ul;t:llLdl;ùl1s may be widely varied within the broad practice of the present
invention; in general, however, perpendicular and rectangular (square)
~e~ldl;ùnsl~;,us between the members are desirable, for ease of alignment and
olitlllldliun relative to the pixels defined by the emitter and anode plates, ashe,~i, Idll~l more fully described.

The standoff elements 20 and the support members 14 and 16 may be integrally
formed from a singie block or other form of precursor material. Alternatively, the
standoff elements 20 may be separately formed and affixed or secured to the grid~ or matrix formed by support members 14 and 16. In any event, the standoff
elements and support members cooperatively formed a unitary support structure
which is i,,~u.,uusable between plates or other structural portions of a displaypanel to contribute strength and ",eul,a"iudl integrity to the display article, and to

WO 9610376~ 2 1 9 6 0 4 0 PCT/US95110028


permit the display to be evacuated to low vacuum levels without undue static load
or, in use dynamic load dt:~icie~ s in the structure and operation of the display
panel article.

Fig ure 2 is an elevation view of the spacer structure 10 and Fig ure 3 is a
bottom plan view of such spacer structure wherein all parts and features of the
structure are col,t,auollui"yly numbered with respect to Figure 1.

The number of "cells" or repeating units in a spacer strurture such as is shown in
Figure 1 (such cells referring to the portion of the structure surrounding a given
open area 1 8 in the structure) will be d~ ll,i,led by the material and
construction, its strength and the frequency of pld~ elll~llt (i.e. number of spacer
segments per unit area of the display panel). These spacer structure segments
can be individually placed at an d~J~JIu,~ddl~ density across display panels of very
large size.

In practice, the spacer structure segments of the type shown in Figures 1-3 may
be i,lt~,uosed between respective emitter and anode plates of the display article,
in continuous fashion with the spacer segments being contiguous to one another
across the full areal extent of the display panel. /'~' u~..iicly the spacer
segments may be disposed in spaced-apart l~:ldliullslli,u to one another across
such areal extent of the display panel interior volume. The specific dlldllgt:lllelll
spacing, size of the spacer segment and frequency may be readily dult:""i"ed
without undue exu~lilll~llldliuo by those of ordinary skill in the art based on
dt~ ll,,iudliùns of static and dynamic loads and deflection levels of the platesutilized in a given display panel with and without support by the spacer structure.

Fig ure 4 is a top plan view of the spacer structure 10 shown in Fig ures 1 -3
(and whose co""~ont:"l elements are cullt::,,uulldi,l~'y numbered with respect to
Figures 1-3) poailioned on a matching field emitter color triad array coi"u,i~i"g
a multiplicity of red color elements 26, green color elements 28, and blue colorelements 30, each of said color element triplets (red, green blue) constituting a
pixel of the overall array.

This Figure 4 e",bodi",c:lll illustrates the manner in which spacer "en:,iolls
can be Illd7~ d and aspect ratios of the support structure reduced by the
dlldn~ lll of the emitter color sub-fields within the pixel. The need to stand up
an individual high aspect ratio spacer element is eliminated by making the spacer

WO 96/03764 2 1 9 6 0 4 0 PCTNS95/10028

1 1
structure segment large enough to cover many pixels, thereby making the aspect
ratio of the spacer structure segment relatively small. The spacer structure
segment is readily handled and requires no greater alignment control than any
other discreetly posilivned element utilized in the display article.

The fine resolution and high aspect ratio capability of the preferred phuLu~u~ dl)le
glass material allows the creation of an open structure for both electron passage
and lateral gas evacuation within the support structure segment. Concerns about
matching of coefficients of exlJallaion are also minimized, since any t~ Jdll:.iVn
mismatch is accumulated over only the length of the spacer structure segment
and not over the entire length of the display article. The clusters of supports in the
spacer structure segment provide greater bearing and racking strength than do
isolated individually placed spacer elements, and afford the potential for greatly
reducing the number of spacer elements requiring pldc~",elll in the interior
volume of the display panel, as dut~,,llliut:d on a unit area of display basis.

The provision of the spacer structure segment of the type illustratively described
he,~:.,aboic likewise serves to minimize costs. The small size of the spacer
structure segment allows hundreds or even thousands of segments to be
fabricated from a plate of precursor (raw) material. The design and divergent
exposure process he,t:i"drlt:r more fully described allows complex three-
di,,,en:.iu,,al stnuctures of the spacer structure segment to be fabricated with a
single exposure which: ' lI;lldlt:S mask ~, ""t:"ts and reduces both processing
and mask costs.

Further, the repetitive pattern of the spacer structure segment allows many types
of damaged segments (standoff elements) such as those with missins corners, to
be employed as long as the remaining spacer structure meets minimum load
requirements. Thus, the spacer structure segment tolerates mechanical
il,,~.e,r~.,t;vn in the standoff elements and enhances the yield character of the
~dbli " n process, particularly in the instance where the standoff elements are
subjected to impact, abrasion, and other forces incident to manufacture and
handling which may result in localized i~pe~ ,tivlls in the bearing surfaces of the
standoff elements.

The spacer structure of the present invention also has benefits in respect of
flashover (arcing) control. Flashover control is of special concern in the
rdLIil;dlivn and operation of flat panel field emitter displays because the small

WO 96/03764 2 1 9 6 0 4 0 PCT/US95/10028

12
spacings clldl d~ ri:~lic of the structure encourage its occurrence. As a
countervailing coll:,ideldlioll it is desirable to use as high an anode potential as
possible in order to improve efficiency and bl iyl ,I"ess beyond the levels
achievable at larger spacing di",t~ iulls. The spacer structures of the present
invention are amenable to a, ' ~ ~ of coatings to selected surfaces or portions
thereof which enhance high voltage operation while reducing the tendency of the
spacer structure to flashover.

Maximum anode potential in operation of the flat panel display is principally
governed by the tendency of charge to suddenly and violently travel across the
spacer surface as the ~iu~ enliuned flashover pheno",elloll. Flashover
generally occurs when the surface charge on the spacer is contiguous enough to
fomn an initiating conductive pathway rather than as a result of the spacer
structure's bulk insulator properties or defects. The maximum potential therefore
is generaliy defined by the absence of flashover. Surface llc:dtlllt~ may be
employed to minimize surface charge while electron bu",L,d,d",e"l (due to normaloperation) generally reduces the maximum potential by i"- ,~a:ii"g surface
charge.

Figure 5 is a perspective view of aflat panel display 100 colll,uliaillg spaced-apart anode plate 102 and cathode plate 104 of a general type in which the
spacer structure of the present invention may advantageously be employed.

Figure 6 is a sectional elevation view of a flat panel display according to one
embodiment of the invention. The display panel 205 comprises a bottom plate
206 which may be formed of glass or other suitable material, on the top surface
which is provided a series of emitters 207 wherein the emitter cc"",e.:tions areoriented perpendicular to the plane of the drawing page. The emitters 207 are
provided with gate row cu,,,,e-liùlls 208, and gate lines 210. The emitters are
constnucted over a vertically conducting resistor layer on the substrate. The panel
205 comprises a top plate 212 of a suitable material such as glass. The top plate
is ",di"L:.,ed in spaced ItlldLio~ J to the bottom plate by means of spacer
elements 213 which feature a flashover control coating 214 on their surfaces
exposed to vacuum space 215.

The spacers at the sides of the display may be sealed to the r-- ~ ' d plates bymeans of frits 216 which may for example comprise silica as their material of
construction. The top plate 212 may be coated on rts lower surface with a black

W096/03764 21 9 6 0 4 0 PCTlUS95/lQ028

~ 13
matrix material, such as a mixture of barium and titanium, and the RGB phosphors217 are disposed on the top plate against the black matrix material 218. The
RGB pl lo~ u,a may optionally be coated with a thin aluminum coating, and may
be provided with an IT0 underlayer.

The emitters shown in the panel alldny~",~"l of Figure 6 may alternatively be
organized in llwl)o~ llle displays, light panels, sequenceable light strips, andother configurations.

Figures 7-10 illustrate the ~dbl; " I of a spacer structure according to a
preferred e",i odi",e"l of the invention.

As shown in Figure 7, a divergent light source 40 is arranged in lightLldll:,lllission l~ldlional,i~, to precursor block 42 formed of a phuluse~silivematerial, such asthe ' ~ el~;u~ed Fotoform glass collllllt:ll,ia"y available from
Corning, Inc. (Corning, NY). The light source 40 is selected to emit divergent light
beams 46 of a selected suitable wavelength and intensity. The upper
(illl~Jillg~ L) surface of the precursor block 42 is masked over a selected area48 by means of masked element 44.

Bysuch d~dngell,~,~t~ the divergent radiation 46 is impinged on surface 49 and
into the interior of the precursor block glass material 42. The mask 44 is
disposed in relation to the divergent radiation 46 so that the surface region 48 is
masked and the radiation path co"t:spu"d;"~ly forms an u"exposecl 42 conical
portion of the precursor block 42, with the remainder of the block being
pl,~ ,pose~l Thus, the divergent light source produces a controlled degree of
exposure under the mask which is d~Jendelll on the distance from the mask or
the image plane in the case of projection printing. When mask features are
narrow in di~enaions, the light from both sides of the mask crosses within th
body of the material, and when developed and etched, results in an illlt~lllledidlt:
height feature. The edges of larger mask features do not meet within the body ofthe precursor block material and therefore result in full height features. In spacer
structure segments, height control in the illlt~lllledidl~ structures is non-critical.

The phutu~,~posed precursor block 42 then is baked and fiood exposed to a
suitable etchant for the material construction of the precursor block. In such
manner, the ~hut ~pùsed portion 52 of the block as shown in Figure 8 is

W O 96103764 ~ 2 1 9 6 0 4 0 PC~rN S9S/10028

14
etchingly removed, yielding the conical-shaped element 50 as a shortened
structure in relation to the height or thickness dimension of the precursor block.

Figures 9 and 10 show an analogous process, utilizing a wider mask, to
produce a truncated inverted conical shape from the precursor block. In Figure
9, the divergent light source 60 is shown as producing divergent light beams 6 6which impinge on the surface 69 which is partially masked by mask element 64
to provide an u,,t,xposed surface portion 68 on the precursor block 62. The
pl,u~ l.osllre is conducted to cw~ lion. The precursor block after
phut~ Ypo.~llre then is baked at suitable elevated temperature to develop the
phhI ~Q~posed portions of the precursor block, following which the block is
subjected to flood exposure of suitable etchant. The etching removes portion 7 2of the precursor block as shown in Figure 10 (wherein the dashed outline
denotes the original bounding surfaces of the precursor block 62 (See Figure
9)), yielding the inverted frualu.,o"ical shape of the standoff element 70.

In general, a wide variety of phutusel,aili,le materials may be utilized in the
production of spacer structures in acco,dal1ce with the present invention. In the
typical process flow, the phutuaell,it;~le material exposed to suitable radiation,
e.g., visible or collimated UV light, while selected areas of the phulusensilivematerial workpiece are masked. The ph..~ )osed image then is developed,
typically under elevated temperature or other development conditions, followed
by optional further development steps including flood exposure in which clear
areas of the previously irradiated workpiece are exposed to u" ", ' UV or
other radiation without a mask, followed by etch or other removal of the non-
masked areas of the workpiece. For example, in the case of a phulusensiti\/e
glass material, the unmasked areas of the workpiece may be dissolved in a
suitable etchant or reagent medium, such as dilute hydrofluoric acid. Finally, the
resulting structural article may be subjected to selected post-treatment ope"~lions
such as C~ldlll' ' ' n and/or heat treatment.

Co",,ua,iaon of Figures 8 and 10 shows that the size and shape of the support
structure elements may be widely varied by the simple expedient of varying mask
size with respect to the resultingly produced shaped member. The technique
illustratively described with reference to Figures 7-10 may be employed to
produce discreet standoff elements which, as previously described, can be
structurally coupled to or secured to other structural elements, e.g., the grid-like
matrix of the support structure 10 shown in Figures 1-4. Alternatively, the

W096/03764 2 1 9 6 0 4 0 PCTIUS95110028

~ 15
precursor block utilized to form the standoff elements may be selectively irradiated
by suitable masking members to produce a unitary, integral support structure,
such as the unitary support structure segment shown in Figures 1-4 hereof.

The anode plate of the flat panel display article of the present invention may be
formed and constructed in any suitable manner, within the skill of the art. In apreferred aspect, such anode plate may be aluminized with a reflective/
conductive aluminum anode layer on the surface of a plate of suitable material
construction, such as glass. This It:ileuii-~i,uu~ductive aluminum anode layer may
suitably be patterned so as to minimize the electric field directly across the spacer
structure and to provide an anode ccr",e.,liol1 point. The patterning colll~Jliaes
aluminized regions on the anode plate substrate member, and non-aluminized
openings defined by the circumscribing aluminized regions. The non-aluminized
openings pass and trap incident light more effectively than a black matrix, thereby
improving sunlight ,~ of the flat panel dispiay (although a black matrix
coating such as titanium or carbon may still be used with such patterned
aluminized layer). Such patterned aluminizing of the anode substrate member
also reduces the potential for culltdlllilldlion of the interior volume of the flat panel
display as a result of the spacer structure p~ujt:utio~ crushing particles or films on
the anode surface, or otherwise removing particulate or otherwise removing
particulate or finely divided metal or other material which can severely adversely
affect the operability of the flat panel display article.

The spacer structure of the present invention may be utilized with surface coatings
of various suitable types, which may for example provide enhanced structural or
",ecl1d"i.ial integrity to the spacer structure or otherwise improve its operating
(electrical) properties. For example, surface coatings on the spacer structure of
slightly leaky insulators may be used to control charging and surface charge
accumulation. Examples of such surface coatings include aluminum silicate,
alumina, and boron. In such respect, ,uhutusellailive glasses such as the
FotoformT~ glass may have very effective surface leakage clldldultlli~ ,s per se as suitable for various ~ a.
.




H will be l~co~u"i~t:d that the phuLufulllli,lg process may be widely varied, asregards the precursor block materials of construction, radiation intensity and
wavelength ~hdld~l~liaLil~s, coherency .,I,d,d~,L~riaLics of the radiation, use of other
than visible light radiation, e.g., ultraviolet or other actinic radiation, variation in
mask size, shape and plact:",e"L, variation in development (e.g., baking

WO 96/03764 2 1 9 6 0 4 0 PCT~S9~/10028

16
conditions) subsequent to initial radiation exposure, and variation in etching
reagents and etch conditions, etching here being broadly construed to include
any sol~ Ih~ ti~ln process by means of which material is removed from a
precursor workpiece sl~hseq~ent to radiation exposure and development.

As an alternative to etching removal of material from photodeveloped v.ol h,uieces,
it is within the purview of the present invention to utilize non-etching removaltechniques, including Ille.,l,a"icdl removal processes and procedures, either for
bulk removal of material, or for finishing of rough-formed support structures.

In respect of electrical clldldulc~ dtiull and o,ut;"~i~dlion of support structures
within the broad purview of the present invention, the testing and o,uLi,,,i~dLion
may be carried out in a manner within the skill of the art. For example, electrical
testing may be carried out by pldcellle:llL of spacer structures between conductive
surfaces onto plates, with the imposition of a variable potential difference across
the spacer structure. Leakage occurrence then can be measured together with
the occurrence and frequency of flashover events. The cathode plate may in such
testing comprise a field emitter array, positioned relative to the spacer structure so
that pixels in known positions may be selectively activated, for purposes of
measurement while the activated pixels are conducting. By use of different
pitches for pixel and spacer co""~on~"L~, pixels with different ,UlUAillliti~s to the
spacer structure can be activated without breaking vacuum conditions, or
otherwise changing empirical conditions, to thereby test the spacer structure's
sensitivity to pixel alignment.

While the invention has been illustratively described with respect to specific
preferred features, aspects, and elllL)odi,lld,lt~, it will be ,t:coy"i~ed that the
invention may be widely varied, and that numerous other variations"" ' ' ls
and alternative elllLJodi",~llt:, are possible, within the spirit and scope of the
present invention.

INDUSTRIAL APPLICABILITY

The flat panel displays of the invention have utility in a wide spectrum of
f p,B- ~- )5, including defense, scientific, medical, educational, business and
rdul~ ~- nal usages, in device ~ ns such as portable work stations, lap
tops, palm tops, pen-based pads, video phones, cellular phones, digital high
definition television (HDTV), and the like.



.....

Representative Drawing
A single figure which represents the drawing illustrating the invention.
Administrative Status

For a clearer understanding of the status of the application/patent presented on this page, the site Disclaimer , as well as the definitions for Patent , Administrative Status , Maintenance Fee  and Payment History  should be consulted.

Administrative Status

Title Date
Forecasted Issue Date Unavailable
(86) PCT Filing Date 1995-07-25
(87) PCT Publication Date 1996-02-08
(85) National Entry 1997-01-27
Dead Application 1998-07-27

Abandonment History

Abandonment Date Reason Reinstatement Date
1997-07-25 FAILURE TO PAY APPLICATION MAINTENANCE FEE

Payment History

Fee Type Anniversary Year Due Date Amount Paid Paid Date
Application Fee $0.00 1997-01-27
Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
JONES, GARY W.
ZIMMERMAN, STEVEN M.
Past Owners on Record
None
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
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Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Drawings 1996-02-08 4 36
Description 1996-02-08 16 643
Cover Page 1998-06-12 1 11
Abstract 1996-02-08 1 34
Claims 1996-02-08 4 121
Cover Page 1997-05-13 1 11
Abstract 1998-06-11 1 34
Description 1998-06-11 16 643
Claims 1998-06-11 4 121
Representative Drawing 1997-06-11 1 7
International Preliminary Examination Report 1997-01-27 18 619
Office Letter 1997-02-25 1 37