Electric lamp or space discharge component or device manufacturi – Process – Electrode making
Patent
1996-06-24
1998-07-28
Ryan, Patrick
Electric lamp or space discharge component or device manufacturi
Process
Electrode making
313496, H01J 920, H01J 9227
Patent
active
057855706
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to anodes for flat display screens. It more particularly relates to the realization of connections of luminescent elements of an anode for color screens such as color screens including microtips.
2. Discussion of the Related Art
FIG. 1 represents the structure of a flat display screen with microtips of the type used according to the invention.
Such microtip screens are mainly constituted by a cathode 1 including microtips 2 and by a gate 3 provided with holes 4 corresponding to the positions of the microtips 2. Cathode 1 is disposed so as to face a cathodoluminescent anode 5, formed on a glass substrate 6 that constitutes the screen surface.
The operation and the detailed structure of such microtip screens are described in U.S. Pat. No. 4,940,916 assigned to Commissariat a l'Energie Atomique.
The cathode 1 is disposed in columns and is constituted, onto a glass substrate 10, of cathode conductors arranged in meshes from a conductive layer. The microtips 2 are disposed onto a resistive layer 11 that is deposited onto the cathode conductors and are disposed inside meshes defined by the cathode conductors. FIG. 1 partially represents the inside of a mesh, without the cathode conductors. The cathode 1 is associated with the gate 3 which is arranged in rows. The intersection of a row of gate 3 with a column of cathode 1 defines a pixel.
This device uses the electric field generated between the cathode 1 and gate 3 so that electrons are transferred from microtips 2 toward phosphor elements 7 of anode 5. The anode 5 is provided with alternate strips of phosphor elements 7, each corresponding to a color (red, green, blue). The strips are separated one from the other by an insulating materiel 8. The phosphor elements 7 are deposited onto electrodes 9, which are constituted by corresponding strips of a transparent conductive layer such as indium and tin oxide (ITO). The groups of red, green, blue strips are alternatively biased with respect to cathode 1 so that the electrons extracted from the microtips 2 of one pixel of the cathode/gate are alternatively directed toward the facing phosphor elements 7 of each color.
The control of the phosphor element 7 (the phosphor element 7g in FIG. 1) that should be bombarded by electrons from the microtips 2 of cathode 1 requires to selectively control the biasing of the phosphor elements 7 of anode 5, for each color.
FIG. 2 schematically illustrates a conventional anode structure. FIG. 2 partially represents a perspective view of an anode 5 fabricated according to known techniques. The interconnection paths 12 and 13 are realized for two (7g, 7b) of the three colors of phosphor elements 7. These paths are connected to pads 15, 16, respectively, which are connected, through electrical links 17 and 18, to a control system (not shown). The connection of the phosphor elements 7r of the third color is achieved, through a connector 20 including pins 18, on pads 14 disposed at one end of each strip of phosphor elements 7r of the corresponding color. The same technique is used for the deposition of phosphor elements 7g, 7b, 7r onto the anode conductor strips with which they are associated. In fact, the phosphor elements 7 are deposited in three successive cataphoresis steps (one for each color). Thus, it must be possible to selectively drive the strips of anode conductors associated with each color.
Using pin connectors requires a plurality of connections, which complicates the structure of the anode and impairs, more particularly, its reliability. In addition, conventional techniques cause a high consumption of expensive metals, especially gold, due to both the anode structure and its fabrication method.
SUMMARY OF THE INVENTION
A specific object of the invention is to avoid the above drawbacks of the prior art techniques by providing an anode for a flat display screen which simplifies the connections between the series of anode conductors and the control system. The invention also aims at simplif
REFERENCES:
patent: 5577943 (1996-11-01), Vickers et al.
patent: 5578902 (1996-11-01), Vickers
patent: 5592056 (1997-01-01), Peyre et al.
Knapp Jeffrey T.
Pixtech S.A.
Ryan Patrick
LandOfFree
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