EP0625277A1 - Flat screen having individually dipole-protected microdots - Google Patents
Flat screen having individually dipole-protected microdotsInfo
- Publication number
- EP0625277A1 EP0625277A1 EP94900903A EP94900903A EP0625277A1 EP 0625277 A1 EP0625277 A1 EP 0625277A1 EP 94900903 A EP94900903 A EP 94900903A EP 94900903 A EP94900903 A EP 94900903A EP 0625277 A1 EP0625277 A1 EP 0625277A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- dipoles
- dipole
- microtips
- produced
- protected
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
- H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
- H01J29/04—Cathodes
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
- H01J1/02—Main electrodes
- H01J1/30—Cold cathodes, e.g. field-emissive cathode
- H01J1/304—Field-emissive cathodes
- H01J1/3042—Field-emissive cathodes microengineered, e.g. Spindt-type
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2201/00—Electrodes common to discharge tubes
- H01J2201/30—Cold cathodes
- H01J2201/319—Circuit elements associated with the emitters by direct integration
Definitions
- the present invention relates to a flat screen with microtips individually protected by dipole.
- Known microtip screens are vacuum tubes generally consisting of two thin glass plates sealed in a sealed manner, the rear plate or cathode plate comprising a matrix array of field effect emitters formed by microtips, and the front plate or anode plate being covered with a transparent conductive layer and phosphors.
- Each light point (pixel) is associated with a cathodic emissive surface located opposite and made up of a large number of microtips (around 10,000 per mm2).
- This emissive surface is defined by the intersection of a line (grid) and a column (cathode conductor) of the matrix. Thanks to the short tip-grid distance ( ⁇
- a potential difference of less than 100 volts applied between line and column makes it possible to obtain at the top of the tip, an electric field sufficient to cause electron emission and high luminance with a low voltage phosphor.
- the conventional structure of the cathode of a microtip screen comprises in particular, deposited successively on a glass or silicon substrate:
- resistive layer of silicon or other material A resistive layer of silicon or other material.
- Cold conductors consisting of a metal layer which can be deposited either below or above the resistive layer.
- An insulating layer (Si or Si02) which constitutes the gate insulator.
- a metallic layer which constitutes the grid or line conductors.
- holes are made in the insulating grid, by known etching techniques, in which the microtips are then produced.
- the main purpose of the resistive layer is to limit the current in each emitter in order to homogenize the electronic emission, and to limit the maximum current which would pass through the tip in the event of a tip / gate short circuit.
- the load characteristic which results from putting a resistance in series with the point is a straight line.
- the voltage drop across this resistor is proportional to the current flowing through it and can be quite large if the current emitted by the tip is large.
- the voltage which must be applied to the tip-resistance protection system is increased by the same amount, which has significant consequences on the consumption of the screen in particular.
- the device according to the present invention proposes to solve these problems. It makes it possible not only to obtain an effective limitation of the current passing through each microtip by self-regulation of the emission current beyond a threshold, even if the tip is in direct contact with the grid, but also a better homogeneity of emission, as well as an efficient and simplified control of the luminance of the screen.
- an emissive flat screen cathode with field emission comprising microtips each protected individually by means of an electrical coupling in series with a dipole formed by a depleting field effect transistor.
- the current-voltage characteristic of such a dipole is not linear.
- FIG. 1 is a cross section illustrating the operating principle of a known microtip screen
- FIG. 2 is an elementary symbolic diagram of a microtip of FIG. 1
- FIG. 3 is an elementary symbolic diagram of a microtip individually protected by a dipole
- FIG. 4 represents the cross section of an emissive microtip cathode according to the invention
- FIG. 5 is a partial section showing in perspective the channel of the field effect transistor around the microtip.
- FIG. 1 The basic principle of a microtip screen is shown diagrammatically in FIG. 1, in which we see successively from bottom to top (in practice from back to front): A plate 1 of glass or silicon, an underlay d coating 2, the cathode conductors or column conductors 3, a resistive layer 4 an insulating layer 5, the line or grid conductors 6, an empty space 7 and a layer of front glass 8 covered on its internal face with a conductive layer transparent constituting the anode 9, and phosphors 10.
- An electron beam 11 emitted under vacuum by the microtips 12 electrically connected to the cathode conductors and modulated by the potential of the grid 6 is accelerated towards the anode 9 where it excites the phosphors 10 (triode type operation). Thanks to the short tip-anode distance, focusing is obtained by proximity effect without any electronic optics.
- each microtip 12 is protected against an excess of current by placing a load resistor in series (FIG. 2).
- This resistance generally consists of a layer resistive 3 of amorphous silicon (or other resistant material).
- each microtip 12 is achieved, no longer by putting a load resistor in series, but by putting a dipole 13 in series with the voltage-current characteristic n is not linear.
- This dipole consists of a field effect transistor (FET), preferably of the type with an insulated depletion gate, the drain D of which is connected to the microtip 12 and the source S to the corresponding column conductor 3, the gate or " gate "G (or pinch electrode) of each transistor being directly connected either to the source S or to the drain D.
- FET field effect transistor
- This arrangement allows complete protection of the microtip 12 against frank short circuits between tip and grid 6 by complete blocking of the current in the tip.
- the dipoles 13 will advantageously be manufactured in integrated technology, on a single silicon substrate 14 (solid or thin layer), so that one can, by polarizing said substrate, which can be common to all the dipoles 13, modify globally (on all points at the same time) the protection threshold and the level of the emission current (modulation of the screen brightness).
- FIG. 4 shows a partial section of an emissive cathode with microtips protected by dipoles 13, these being produced from a P-type substrate 14 in which overdoped zones 15 of the type are formed.
- N obtained by diffusion or other (implantation) and constituting the sources, the channel 20 (depletion transistor) formed for example by an N-type ion implantation, as well as an insulating layer of gate 16 made of silica obtained by surface oxidation or deposition .
- the pinch electrode 17 is created at the same time as the column conductor 3 by metallization.
- the tip is produced in the usual way, but rests on the pinch gate of the transistor.
- the drains located under the microtips are not overdoped, as usually in conventional MOS structures.
- the field effect transistor constituting the dipole 13 can advantageously have a circular geometry, its conduction channel being situated all around the microtip 12 (FIG. 5).
- the operation of the dipole 13 is then as follows: The extraction voltage is applied to the electrode 6 (grid). When this voltage is low (low enough for the peak / source voltage to be less than the threshold of the depletion transistor), the dipole in series with the tip 12 is roughly equivalent to the resistance of the channel 20 implanted, its value is quite weak. When the extraction voltage increases so that the peak / source voltage is of the order of, or greater than, the threshold of said depletion transistor, the pinch gate 17 does its job and "clamps" the channel 20 limiting the current in the dipole at a value
- saturation current of the depletion transistor which is, in the first order, only a function of the geometric dimensions of the assembly and the voltage of the substrate 14 relative to the source 15.
- the voltage loss in the dipole n being more function itself current in the tip, but only the threshold voltage of said depletion transistor. In fact each point will be crossed by the saturation current of the depletion transistor which protects it.
- the geometries of said transistors being identical, the currents in the tips (whatever the specific emission characteristics of the tips) will be identical.
- the emissive cathode can itself be produced on silicon using integrated technology.
- the column conductors 3, and possibly the row conductors (or grid 6) may be made up of diffused layers, buried or not, with the alternative of doubling, in places, the layer diffused by metallization (positioned in an uncluttered sector for example or in such a way as to minimize coupling capacities)
Landscapes
- Cold Cathode And The Manufacture (AREA)
- Control Of Indicators Other Than Cathode Ray Tubes (AREA)
- Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
Abstract
Un écran plat à micropointes protégées individuellement par dipôle est constitué d'une cathode émissive à émission de champ comportant des micropointes (12) protégées chacune individuellement grâce à un couplage électrique en série avec un dipôle (13) formé d'un transistor à effet de champ à déplétion, les dipôles étant réalisés de telle façon que l'on puisse modifier sur toutes les pointes en même temps le seuil de protection et le niveau du courant d'émission, en agissant uniquement sur la polarisation du substrat (14) commun de ces dipôles. Il concerne d'une façon générale le domaine des écrans d'affichage ou de visualisation.A flat screen with microtips individually protected by dipole consists of an emissive cathode with field emission comprising microtips (12) each protected individually by means of an electrical coupling in series with a dipole (13) formed by an effect transistor. depletion field, the dipoles being produced in such a way that the protection threshold and the level of the emission current can be modified on all the points, by acting only on the polarization of the common substrate (14) of these dipoles. It generally relates to the field of display or display screens.
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR9214893A FR2698992B1 (en) | 1992-12-04 | 1992-12-04 | Flat screen with microtips individually protected by dipole. |
FR9214893 | 1992-12-04 | ||
PCT/FR1993/001190 WO1994014153A1 (en) | 1992-12-04 | 1993-12-03 | Flat screen having individually dipole-protected microdots |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0625277A1 true EP0625277A1 (en) | 1994-11-23 |
EP0625277B1 EP0625277B1 (en) | 1998-06-17 |
Family
ID=9436433
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP94900903A Expired - Lifetime EP0625277B1 (en) | 1992-12-04 | 1993-12-03 | Flat screen having individually dipole-protected microdots |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP0625277B1 (en) |
JP (1) | JP3486904B2 (en) |
DE (1) | DE69319225T2 (en) |
FR (1) | FR2698992B1 (en) |
WO (1) | WO1994014153A1 (en) |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5514937A (en) * | 1994-01-24 | 1996-05-07 | Motorola | Apparatus and method for compensating electron emission in a field emission device |
JP3026484B2 (en) * | 1996-08-23 | 2000-03-27 | 日本電気株式会社 | Field emission cold cathode |
JP2000260299A (en) * | 1999-03-09 | 2000-09-22 | Matsushita Electric Ind Co Ltd | Cold electron emitting element and its manufacture |
US6648711B1 (en) * | 1999-06-16 | 2003-11-18 | Iljin Nanotech Co., Ltd. | Field emitter having carbon nanotube film, method of fabricating the same, and field emission display device using the field emitter |
JP4670137B2 (en) * | 2000-03-10 | 2011-04-13 | ソニー株式会社 | Flat panel display |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2656843B2 (en) * | 1990-04-12 | 1997-09-24 | 双葉電子工業株式会社 | Display device |
JPH04221990A (en) * | 1990-12-25 | 1992-08-12 | Sony Corp | Image display device |
US5212426A (en) * | 1991-01-24 | 1993-05-18 | Motorola, Inc. | Integrally controlled field emission flat display device |
-
1992
- 1992-12-04 FR FR9214893A patent/FR2698992B1/en not_active Expired - Fee Related
-
1993
- 1993-12-03 EP EP94900903A patent/EP0625277B1/en not_active Expired - Lifetime
- 1993-12-03 WO PCT/FR1993/001190 patent/WO1994014153A1/en active IP Right Grant
- 1993-12-03 JP JP51385294A patent/JP3486904B2/en not_active Expired - Fee Related
- 1993-12-03 DE DE69319225T patent/DE69319225T2/en not_active Expired - Fee Related
Non-Patent Citations (1)
Title |
---|
See references of WO9414153A1 * |
Also Published As
Publication number | Publication date |
---|---|
WO1994014153A1 (en) | 1994-06-23 |
JPH07506456A (en) | 1995-07-13 |
JP3486904B2 (en) | 2004-01-13 |
FR2698992A1 (en) | 1994-06-10 |
DE69319225D1 (en) | 1998-07-23 |
DE69319225T2 (en) | 1998-11-19 |
EP0625277B1 (en) | 1998-06-17 |
FR2698992B1 (en) | 1995-03-17 |
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