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
  • H01J29/86—Vessels; Containers; Vacuum locks
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J31/00—Cathode ray tubes; Electron beam tubes
  • H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
  • H01J31/10—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes
  • H01J31/12—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes with luminescent screen
  • H01J31/123—Flat display tubes
  • H01J31/125—Flat display tubes provided with control means permitting the electron beam to reach selected parts of the screen, e.g. digital selection
  • H01J31/127—Flat display tubes provided with control means permitting the electron beam to reach selected parts of the screen, e.g. digital selection using large area or array sources, i.e. essentially a source for each pixel group
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2201/00—Electrodes common to discharge tubes
  • H01J2201/30—Cold cathodes
  • H01J2201/304—Field emission cathodes
  • H01J2201/30446—Field emission cathodes characterised by the emitter material
  • H01J2201/30453—Carbon types
  • H01J2201/30469—Carbon nanotubes (CNTs)

Definitions

• the present invention relates generally to the field of cold cathode electronic tubes.
• the invention particularly relates to a method of manufacturing a cathodoluminescent capsule comprising at least one envelope capable of being closed, sealed and evacuated, a cold cathode emitting electrons by field effect, an anode and a control gate, the envelope being at least formed of a first internal wall receiving the electrons.
• the present invention aims to provide in particular a cathodoluminescent capsule and its manufacturing method free from at least one of the limitations mentioned above, allow to realize large display panels (for example more than 3 meters of sides).
• the invention aims in particular to reduce the size of the electronic tubes, as well as their heating, and to propose a suitable non-complex manufacturing process.
• the invention notably proposes a cathodoluminescent capsule that can operate at low voltage (for example between 5 and 7kV), preferably using a cold source, preferably having millimeter dimensions, as well as an optimization of the quality of the image.
• each capsule can be a pixel of a display panel that can be consisting of hundreds of thousands of these capsules, to obtain a high quality video image.
• the capsules can also be applied to lighting or backlighting systems.
• a cathodoluminescent capsule comprising at least one envelope, a cold cathode emitting electrons by field effect, an anode and a control gate, the casing being at least formed of a first inner wall adapted to receive the electrons and disposed facing the cathode.
• the method comprises at least the steps of: depositing a phosphor layer and a reflective layer at least on the first inner wall, the phosphor layer being between the first inner wall and the reflective layer;
• a conductive layer on at least a portion of a second internal wall adjacent to the first inner wall, the conductive layer being at least in contact with the phosphor layer; providing a base carrying at least the anode, the cathode and the control gate, the base being further provided with an open tube; assembling the base with the envelope to close and form the capsule, the anode being brought into contact with the conductive layer and the phosphor layer being placed facing the cathode; - Vacuuming the capsule via the tube of the base; and
• the casing and the base may be made of glass, and the embodiment of the base may comprise at least the steps of: pressing and melting of glass around three metal conductors; and
• the assembly step comprises at least steps of:
• the vacuum of the capsule is to make a secondary vacuum.
• the sealing of the tube of the base is made by melting the outer end of the tube of the base a few millimeters long to plug the tube.
• the invention also relates to a cathodoluminescent capsule consisting of at least one envelope, a cold cathode emitting electrons by field effect, an anode and a control gate, the envelope being at least formed of a first inner wall adapted to receive electrons emitted by the cold cathode.
• the capsule further comprises: a phosphor layer and a reflective layer on the first inner wall, the phosphor layer being interposed between the first inner wall and the reflective layer, the cathode being preferably placed facing the reflective layer;
• a conductive layer on at least a portion of a second internal wall adjacent to the first wall, providing at least one electrical connection between the anode, the phosphor layer and the reflective layer; a base comprising at least first, second and third metal conductors respectively welded to the anode, the cathode and the control gate; and
• the cathode is formed of at least one carbon nanotube and is a cold cathode of nanometric dimension.
• the cold cathode is for example formed of at least one carbon nanotube, or carbon fibers, or a carbon film in crystalline form.
• control gate includes a getter advantageously to maintain the vacuum in the capsule.
• the second inner wall of the casing may be tubular, of thickness at most equal to 1 millimeter, of diameter and length of between 1 millimeter and 10 millimeters.
• the invention also relates to a display device comprising at least a plurality of individual display elements distributed in a matrix on a substrate, and a set of control means for these individual display elements, each individual element of the display element.
• display being a cathodoluminescent capsule as described above.
• FIG. 1 shows a schematic section of a cathodoluminescent capsule according to a particular embodiment of the invention
• - Figure 2 shows the main steps of a manufacturing method according to a particular embodiment of the invention.
• the cathodoluminescent capsule 1 (or electron tube cold cathode or microtube), Figure 1, comprises in particular a sealed envelope 10 with a base 80, a cathode 20 (or source) cold emitting field effect electrons, an anode 30 and a control gate 40 (or control electrode).
• the cold cathode may consist of carbon nanotubes and may have a structure as disclosed in Application FR 2 857 379.
• the cathode may also be a metal tip, for example nickel or tantalum or Kovar, on which nanotubes grow. carbon (or CNT).
• the control gate 40 preferably made of a metal part, for example of annular or lattice shape, makes it possible to control the emission of electrons by controlling the electric field in the vicinity of the cathode 20.
• the gate is positioned symmetrical way with respect to the axis of the cathode.
• the envelope 10 (or bulb) is for example made of transparent glass, such as the glasses conventionally used for cathode ray tubes, of tubular form having, for example, a diameter D of 8 millimeters, a length L of 8 millimeters, and a thickness e of 1 millimeter.
• the envelope 10, preferably open, is for example formed of a first inner wall 101 for receiving the electrons emitted by the cold cathode 20.
• the base 80 preferably made of glass, comprises for example first, second and third metal conductors respectively welded to the anode, the cathode and the control gate.
• the capsule may further include: a phosphor layer 50, a material emitting light when it receives electrons of sufficient energy (for example phosphorus), on the first internal wall 101, the cathode being placed facing the phosphor layer 50; a reflective layer 60 (for example of aluminum or silver) deposited such that the phosphor layer 50 is interposed between said first inner wall 101 and this reflecting layer 60, this reflecting layer having the advantage of intensifying the emitted light by phosphores; and a conductive layer 70 (eg graphite or carbon) on a second inner wall 102 adjacent to the first inner wall 101, providing at least the contact between the anode 30 and the phosphor layer 50.
• a phosphor layer 50 a material emitting light when it receives electrons of sufficient energy (for example phosphorus), on the first internal wall 101, the cathode being placed facing the phosphor layer 50
• a reflective layer 60 for example of aluminum or silver
• a conductive layer 70 eg graphite or carbon
• the phosphor 50 and reflective layers 60 are deposited on the entire surface of the first inner wall 101.
• This capsule can thus emit a constant red, green or blue light by excitation of phosphors using electron beams generated by a carbon nanotube emitter.
• This cathodoluminescent capsule 1 can be made according to a particular manufacturing process, including in particular the following steps (FIG. 2):
• A deposition of a phosphor layer 50 and a reflective layer 60 at least on the first inner wall 101, the phosphor layer 50 being interposed between the first inner wall 101 and the reflective layer 60. It is for example possible to deposit the phosphor layer using the methods used in the manufacture of conventional cathode screens.
• B depositing a conductive layer 70 on a second inner wall 102 adjacent to the first inner wall 101, this conductive layer 70 being at least in contact with the phosphor layer 50; The envelope thus produced can be cleaned and stored cleanly until the final assembly.
• the base 80 comprises at least first, second and third metal conductors 21, 31, 41 respectively welded to the anode 30, the cathode 20 and the gate 40 control.
• the base 80 is obtained by pressing and melting of glass around the metal conductors whose composition allows a glass-metal seal.
• the base 80 is further provided with an opening on which is welded a tube 90 (preferably also glass) open to perform the evacuation of the capsule. All the electrodes (cathode 20, anode 30 and control gate 40) are preferably laser-welded to the connectors of the base 80 in order to maintain a determined position between them.
• the position of the connector of the cathode is offset relative to the position of the tube 90 of the base.
• D assembly of the base 80 with the envelope 10 to form the capsule 1, the anode 30 being brought into contact with the conductive layer 70 and the cathode 20 being placed facing the phosphor layer 50.
• a part of the glass of the base 80 and a part of the glass of the envelope are heated until melting. These melt parts are then positioned and put in contact, and a rotation of the base and the envelope allows to mix these two melt parts.
• the assembly is cooled to seal the base with the envelope sealingly. The assembly must further ensure an exact position of the emitter in front of the phosphors.
• E the capsule is then placed on a vacuum pump via the tube 90 of the base 80.
• the vacuum may consist in a high vacuum (e.g. of the order of 10 "8 torr) F.
• a high vacuum e.g. of the order of 10 "8 torr
• this operation consists for example in melting an end of the tube 90 a few millimeters long which retracting will plug and maintain the capsule under empty.
• the control gate 40 can integrate an active getter.
• This getter (or degasser) is a substance for maintaining the vacuum at a good level by absorbing the residual gases that would have remained in the capsule after sealing the tube 90 of the base.
• the getter also allows a maintenance of the vacuum level such as after the sealing operation.
• An operation to check the proper functioning of the capsule can then be conducted. During this operation all the performance characteristics and main operating points of the capsule can be adjusted.
• cathodoluminescent capsules may be used in the production of a display device.
• this display device comprises a plurality of these cathodoluminescent capsules distributed in a matrix on a substrate, each capsule preferably representing an individual display element (or pixel).
• the substrate may further comprise a set of control means for these capsules.
• the combination of three different capsules of the three colors red, green and blue, will generate a color image and realize a large viewing panel (for example more than 3 meters) with a video image of high quality.
• the screen has a size greater than 5.8 meters for example, it will have a definition of the VGA (Video Graphics Array) type, seen at a distance sufficient for the visual resolution to be very large in front of the size of the capsules.
• the substrate may be a flexible polymer to ensure the panel a great flexibility of use.
• These capsules can be used in the realization of billboard advertising, big screen cinema, sports information and airport.
• the size of each capsule can be optimized to ensure optimum matrix assembly of the light spots or a correct white balance (or gamut), for example with a larger size for green light emitting capsules.
• the phosphors are designed to work at low voltages (preferably less than 10 kV).
• the supply of the capsule can be done using a voltage of 2 to 5 kV to provide a current of at least 100 ⁇ A to excite the phosphors.
• the electron beam emitted from the cathode to the wall makes an angle ⁇ preferably between 10 and 20 degrees, for example 15 degrees.
• ⁇ preferably between 10 and 20 degrees, for example 15 degrees.
• the connectors 21, 31, 41 of the base can for example be positioned on a diameter of 3 to 4 mm and can be located respectively at 0 °, 90 ° and 180 ° of the axis X of the capsule.
• the distance of the connector 21 of the cathode relative to the tube 90 is for example between 0.5 and 1 mm.
• the thicknesses of the phosphor, reflective and conductive layers 50, 60, 70 are respectively 0.2 mm, 0.2 mm and 0.3 mm.
• the getter is for example made of porous barium metal and can be laser welded to one of the walls of the grid 40 in the shadow of the passage of the electron beam.

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• Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=40674187

Family Applications (1)

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• 2008
  • 2008-10-15 FR FR0856984A patent/FR2937180B1/fr not_active Expired - Fee Related
• 2009
  • 2009-09-07 WO PCT/FR2009/051683 patent/WO2010043793A1/fr active Application Filing
  • 2009-09-07 US US13/123,985 patent/US20110266941A1/en not_active Abandoned
  • 2009-09-07 EP EP09743901A patent/EP2335267A1/de not_active Withdrawn

Non-Patent Citations (1)

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