WO1994010700A1

WO1994010700A1 - Matrix addressed screen with row/column contacts through the substrate

Info

Publication number: WO1994010700A1
Application number: PCT/FR1993/001062
Authority: WO
Inventors: Jean-Luc Grand Clement; Michel Garcia
Original assignee: Pixel International S.A.
Priority date: 1992-10-29
Filing date: 1993-10-28
Publication date: 1994-05-11
Also published as: FR2697660B1; FR2697660A1

Abstract

A matrix addressing screen with row/column contacts through the substrate. The screen consists of a flat matrix addressed screen in which conductive areas (9) are formed in a known manner through a rear substrate (1) in order to locate the row (4)/column (2) contacts directly on the back of the screen, and is useful in the field of flat row/column addressed display screens, in particular those using microdot technology, i.e. consisting of a vacuum tube made up of two thin glass plates (1, 6) containing a field-effect emitter array and an anode (7) having electroluminescent elements.

Description

MATRIX ADDRESSING SCREEN WITH TAKING CONTACT LINES AND COLUMNS THROUGH THE SUPPORT

The present invention relates to a screen with matrix addressing with row and column contact making through the support.

It generally relates to the field of flat display screens with row-column matrix addressing, and more particularly display screens using microtip technology, that is to say constituted by a vacuum tube formed of two thin glass plates, the rear plate or cathode plate comprising a matrix array of field effect emitters deposited by thin film techniques, and the front plate or anode plate being covered with a transparent conductive layer and phosphors .

In this type of screen, each light point (pixel) is associated with an emissive surface located opposite and made up of a large number of microtips. This emissive surface is defined by the intersection of a line (grid) and a column (cathode conductor) of the matrix.

Microtip screens are characterized by electronic field effect emission from an extended flat cathode with microtips, a low consumption cold cathode, a fast response time (1 μs), matrix addressing from the structure integrated tip-grid and light emission by low to medium voltage cathodoluminescence.

The cathode of a microtip screen consists essentially of three deposited layers successively on a glass or silicon substrate, namely: a metallic layer (Niobium or Aluminum) playing the role of "column conductor", an insulating layer (Si02) and a second metallic layer constituting the grid. Some embodiments include a fourth resistive silicon layer deposited above or below the "column conductor" layer. After depositing the above layers, holes are made in the grid and the insulating layer in which the microtips are then deposited.

To date, the contact points for rows and columns of flat screens with matrix addressing of all types have come out on the edge of the screen, which requires a lateral connector increasing the size of the screens and not allowing their juxtaposition.

The device according to the present invention eliminates these drawbacks. Indeed, it allows a random taking of the row and column contacts on the rear face of the cathode, the elimination of the connectors at the edge of the screen and therefore a reduction in the lateral dimensions as well as the possibility of juxtaposing several cathodes one at a time. side of the others without discontinuities.

It consists of a flat screen with matrix addressing in which conductive zones have been produced by known means through the rear substrate so as to be able to directly transfer the contact points for rows and columns to the rear face of said screen. In the accompanying drawings, given by way of nonlimiting examples of embodiments of the subject of the invention: FIG. 1 is a schematic cross-section of a flat microtip screen in the rear substrate from which conductive zones have have been formed by local modification of the structure of the constituent material, and FIGS. 2 and 3 show, under the same conditions, the cathode of the screen in which conductive zones have been formed by various methods described below.

A microtip screen successively comprises from back to front: a rear layer or cathode substrate 1, the cathode conductors or column conductors 2 carrying the microtips, an insulating layer 3, the line or grid conductors 4, an empty space 5 and a front glass layer 6, covered on its internal face with a transparent conductive layer constituting the anode 7, as well as phosphors in contact with said anode.

An electron beam is emitted under vacuum by the microtips and modulated by the potential of the grid 4 is accelerated towards the anode 7 where it excites the phosphors (triode type operation).

Thanks to the short tip-anode distance, focusing is obtained by proximity effect without any electronic optics.

The conventional structure of the cathode 8 of a microtip screen comprises, successively deposited on the rear substrate 1 of glass or silicon: - A coating sublayer (not shown). - The "column conductor" 2 consisting of a metallic layer of Niobium, Aluminum or other conductor.

- An insulating layer 3 (Si02 for example) which constitutes the grid insulator.

- A metallic layer of Niobium for example which constitutes the grid 4.

According to the embodiments, other layers intended to improve the functioning of the system can complete this set. For example a "resistive layer" of silicon which can be deposited either below or above the metal layer constituting the "column conductors" 2.

The inventive principle of the invention consists in using one of the known techniques for producing conductive zones through the rear substrate 1 so as not to have to take out the row and column contacts on the edge of the screen like this. is done today, but to be able to directly transfer the contact to the rear face of the cathode.

This has the advantage of allowing contact to be made at any level of the column or of the line (subject to certain precautions not described here) and no longer systematically at the end of the line or column. This saves space by removing the side connector and saving a connection operation, which enables contact on small screens and offers the possibility of juxtaposition of several cathodes side by side without discontinuities due to contact between rows and columns (production of large screens by the juxtaposition of several cathodes: mosaic screens). In the case of the rear glass substrate 1, two techniques exist.

The first is to use a specially charged glass and to locally insulate it using a laser or other beam of energy.

The laser exposure promotes the migration of the salts previously included in the glass, these precipitate and a conductive passage 9 ("via") is created through the thickness. This method is known to some glass manufacturers. It requires the use of a specially prepared glass.

The second technique is not specific to glass. It is used in the production of printed circuits. This is called the metallization of the holes.

In a multilayer printed circuit to connect the different layers to each other, thin holes (about 100 microns) are made which are then metallized. This metallization phase is such that the hole is plugged after the operation.

The idea developed here is to take inspiration from this technique and transpose it to flat screens. It is therefore a question of making holes 10 in the glass at precise locations to allow contact to be made on the rows or columns and then to fill them with metal 11 as is done in the technique of printed circuits.

To make the holes in the glass, one can use any of the methods known by glass specialists (use of a drill, use of an energy beam, use of a chemical, plasma or other etching) .

Other techniques are also possible. For example, metal piles 12 are inserted into a hole 10 previously made in the glass, then fixed by glass-metal sealing or use of a loaded glue, etc. The hole 10 can also be filled with a paste 13 of epoxy type resin or the like charged with metallic particles making it conductive.

In the case of the silicon substrate, either the technique derived from the metallization of the holes in the printed circuits of which we have just spoken is used, the holes 10 being produced by chemical etching in a plasma (Reactive Ion (s) Etching) or all other suitable means, either conductive passages ("vias") are carried out by diffusion of impurities through the substrate 1, diffusion of aluminum, for example.

The electrical connections between grid 4 (line conductors) and conductive passages 9, 12, 13 or metallized holes 10 of the cathode substrate 1 are produced by diffusion of impurities 14 through the insulating layers 3, resistive or otherwise, or by making a well 15 in said layers allowing the metal layer forming the grid 4 to be in contact with the conductive element, or any other technique making it possible to obtain the same result.

The positioning of the various constituent elements gives the object of the invention a maximum of useful effects which had not, to date, been obtained by known methods.

Claims

1 °. Matrix addressing screen with contact of rows and columns through the support, particularly applicable to display devices using microtip technology, and in general to flat display systems with matrix addressing comprising in particular a layer back or substrate (1), column conductors (2), an insulating layer (3) and line conductors (4), characterized by the combination of a flat screen in which conductive zones (9, 11, 12, 13) have been produced by known means through the rear substrate (1) at precise locations so as to be able to directly transfer the contact points for rows and columns to the rear face of said screen.

2 °. Device according to claim 1, characterized in that electrical connections are established between grid conductors of lines (4) and the conductive areas (9, 11, 12, 13) of the rear substrate (1), these connections being obtained by diffusion of impurities (14), by making a well (15) in the insulating layers allowing the metal layer forming the line conductors (4) to be in contact with a conductive area, or by an equivalent technique .

3 °. Device according to any one of the preceding claims, characterized in that the rear substrate (1) is made of glass and that, for the creation of the conductive zones, holes (10) are made by any means known in the art. this glass, these holes being filled with metal (11) thanks to the technique of metallized holes used for printed circuits.

4 °. Device according to claims 1 and 2, characterized in that the rear substrate (1) is made of glass and that, for the creation of the conductive zones, holes (10) are made by any means known in this glass , metal piles (12) being inserted into said holes, and fixed by glass-metal sealing, use of a charged adhesive, or equivalent technique.

5 °. Device according to Claims 1 and 2, characterized in that the rear substrate (1) is made of glass and that, for the creation of the conductive zones, holes (10) are made by any known means in this glass , said holes being filled with a paste (13) of epoxy resin type or other charged with metallic particles making it conductive.

6 °. Device according to claims 1 and 2, characterized in that the rear substrate (1) is made of a specially loaded glass and that, for the creation of the conductive zones, this glass is exposed locally using a laser or other beam of energy so as to promote the migration of salts previously included in said glass to cause them to precipitate and thus create conductive passages (9) through the thickness of said rear substrate.

7 °. Device according to claims 1 and 2, characterized in that the substrate rear (1) is made of silicon and that, for the creation of conductive areas, holes (10) are made in this substrate by any known means, and metallized according to the technique used for printed circuits.

8 °. Device according to claims 1 and 2, characterized in that the rear substrate (1) is made of silicon and that, for the creation of the conductive zones, conductive passages are made by diffusion through the substrate, of impurities such as than aluminum particles.