CA1319389C - Microdot trichromatic fluorescent screen - Google Patents
Microdot trichromatic fluorescent screenInfo
- Publication number
- CA1319389C CA1319389C CA000604030A CA604030A CA1319389C CA 1319389 C CA1319389 C CA 1319389C CA 000604030 A CA000604030 A CA 000604030A CA 604030 A CA604030 A CA 604030A CA 1319389 C CA1319389 C CA 1319389C
- Authority
- CA
- Canada
- Prior art keywords
- bands
- anodes
- va3max
- addressing
- series
- 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.)
- Expired - Fee Related
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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
- H01J29/08—Electrodes intimately associated with a screen on or from which an image or pattern is formed, picked-up, converted or stored, e.g. backing-plates for storage tubes or collecting secondary electrons
-
- 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
- H01J29/08—Electrodes intimately associated with a screen on or from which an image or pattern is formed, picked-up, converted or stored, e.g. backing-plates for storage tubes or collecting secondary electrons
- H01J29/085—Anode plates, e.g. for screens of flat panel displays
-
- 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
- H01J31/15—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes with luminescent screen with ray or beam selectively directed to luminescent anode segments
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N9/00—Details of colour television systems
- H04N9/12—Picture reproducers
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Control Of Indicators Other Than Cathode Ray Tubes (AREA)
- Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
- Devices For Indicating Variable Information By Combining Individual Elements (AREA)
Abstract
DESCRIPTIVE ABSTRACT.
Microdot trichromatic fluorescent screen constituted by two facing substrates (10,22). The first substrate (10) supports cathode conductors (12) provided with microdots (14), grids (16) and an insulating layer (18) separating the same. The second sub-strate (22) supports three series of parallel conductive bands (26). The conductive bands (26) of each series are electrically interconnected and covered with a material (28,29,30) luminescing in one of the three primary colours red, green and blue. Each series of conductive bands (26) corresponds to a red, green or blue anode (A1, A2, A3).
During its production, this screen requires no positioning between the two substrates (10,22).
Application to the display of fixed or moving pictures.
(Fig. 3) B 9678.3 PM
Microdot trichromatic fluorescent screen constituted by two facing substrates (10,22). The first substrate (10) supports cathode conductors (12) provided with microdots (14), grids (16) and an insulating layer (18) separating the same. The second sub-strate (22) supports three series of parallel conductive bands (26). The conductive bands (26) of each series are electrically interconnected and covered with a material (28,29,30) luminescing in one of the three primary colours red, green and blue. Each series of conductive bands (26) corresponds to a red, green or blue anode (A1, A2, A3).
During its production, this screen requires no positioning between the two substrates (10,22).
Application to the display of fixed or moving pictures.
(Fig. 3) B 9678.3 PM
Description
13~93~,~
The present invention relates to a microdot trichromatic fluorescent screen, its addressing process and its production process. This type of screen is more particularly used in the colour display of fixed or moving images or pictures.
me known microdot ~luorescent screens are monochromatic, a description being provided in the report of the "Japanese Display 86 Congress"; p. 512 or in French patent application published under No. 2, 568,394 on January 31, 1986. The procedure used for monochromatic screens can be extrapolated to trichromatic screens.
More specifically, the present invention relates to a microdot trichromatic fluorescent screen having a first substrate on ~hich are arranged in the two directions of the matrix conductivecolumns (cathodeconductors) supportingthemicrodots and above the columns perforated conductive rows (grids), the rows and columns being separated by an insulating layer having apertures permitting the passage of the microdots, each intersection of a row and a column corresponding to a pixel.
On a second substrate facing the first, said screen has regularly spaced, parallel conductive bands, which are alternately covered by a material luminescing in the red (these bands forming a so-called red anode), a material luminescing in the green (these bands forming a so-called green anode) and a material luminescing in the blue (these bands forming a so-claled blue anode), the conductive bands covered by the same luminescent material being electrically interconnected.
m is arrangement of three anodes in comb-like configuration on the second substrate makes it possible to overcome any positioning problem. For example, ~he conductive bands of the anodes are placed substantially in the same direction as the .,'' -~
131~389 cathode conductors, three successive red, green and blue bands advantageously facing a cathode conductor.
As the conductive bands can obviously assume any direction with respect to that of the cathode conductors. Moreover, the number of conductive bands is independent of the number of cathode conductors. Preferably, the number of conductive bands is greater than three times the number of cathode conductors in order to ensure a better visual fusion of the colour.
The presen~ invention also relates to a process for addressing a microdot trichromatic fluorescent screen. This process consists of successively raising the anodes Ai, i ranging from 1 to 3, periodically to a potential VAimax adequate for attracting the electrons emitted by the microdots of the cathode conductors corresponding to the pixels which are to be "illuminated/switched on" in the colour of the considered anode Ai. When they are not raised to th~ potential VAimax, the anodes Ai are raised to a potential VAimin, such that the electrons emitted by the microdots are repelled or have an energy below the threshold cathodoluminescence energy of the luminescent materials covering the anodes Ai.
In a first preferred embodiment, the display of a trichromatic field or frame of the image takes place during a frame time T, the anodes Ai being raised to the potential VAimax for a period equal to the frame time T, the latter being divided into three times tl, t2 and t3 corresponding to the times during which the anodes Al, A2 and A3 are raised to the potentials VAlmax, VA2max and VA3max.
In a second preferred embodiment, the display of a trichromatic frame of the image takes place by sequentially addressing each row of the grid conductor for a selection time t, the anodes Ai being raised to the potential VALmax for a period equal to the 3 8 ~
selection time t, the latter being divided into three periods ~ 2 and ~3 corresponding to the times during which the anodes Al, A2 and A3 are raised to the potentials V~lmax, ~A2max and VA3max.
In these embodiments of the proces~, the three colours are never displayed at the same time. The colour sensation on a broad spectrum perceived by an observer of the screen is due to a reconstitution of the coloured spectrum by the viewer's eye.
The eye is a "slow" detector compared with the screen frame time and the perception of the full colour is due to an aYeraging effect over several frames of the image or picture.
m e present invention also rela~es to a process for the production of a microdot trichromatic fluorescent screen. This production process comprises covering the second substrate with a conductive material, etc~ing in said material regularly spaced, parallel bands, which are alternately grouped into three series, a first series of said bands being electrically connected by a first conductive material connection band, the latter being perpendicular to the parallel bands and is placed at one of the ends thereof, a second series of said parallel bands being electrically connected by a second conductive material connection band, the lat~er being perpendicular to the parallel bands and placed at the other end thereof, electrically interconnecting the third series of parallel bands by an anisotropic conductive ribbon or tape and covering a series of parallel bands by a material able to emit luminescence in the red, a second series of parallel bands by a material able to emit luminescence in the blue and the final series of parallel bands by a material able to emit luminescence in the green.
The conductive material of the first and second connection bands can be the same as that of the parallel bands~
/J, , 8 ~
In a variant of the production process, the first and second connection bands are anisotropic conductive ribbons.
Other features and advantages of the invention can be gathered from the following non-limitative description with reference to the drawings, wherein show:
Fig. 1 illustrates diagrammatically and in perspective a trichromatic screen extrapolated from a monochromatic screen.
Fig. 2 illustrates diagrammatically a section of a trichromatic screen extrapolated from a monochromatic screen.
Fig. 3 diagrammatically and in perspective a screen according to the invention.
Fig. 4 diagrammatically a connection method between the conductive bands.
Fig. 5 diagrammatically another connection method between the conductive bands.
Fig. 6 diagrammatically a section of a screen according to the invention.
Fig. 7 the timing charts relating to a first process for addressing a screen according to the invention.
Fig. 8 the timing charts relating to a second process for addressing a screen according to the invention.
Fig. 1 diagrammatically shows in perspective a trichromatic screen which could be extrapolated from a monochromatic screen.
On a first e.g. glass substrate 10 are arranged conductive columns 12 (cathode conductors) supporting metal microdots 14.
The columns intersect perforated conductive rows 15 (grids).
All the microdots 14 positioned at an intersection of a row and a column have their apex substantially facing a perforation of the row. Cathode conductors 12 and grids 16 are separated by an e.g. silica insulating layer 18, which has openings or apertures s. ,~^3~
13193~
permitting the passage of the microdots 14.
A layer 20 of conductive material (anode) is deposited on a second transparent, e.g. glass substrate 22. Parallel bands 24 alternately in red, green and blue phosphor are deposited on the anode 20 facing the ca~hode conductors 12. The bands can be replaced by a mosaic pattern.
In this con*iguration, it is necessary to have a triplet of cathode conductors 12 (one facing a red band, another facing a green band and another facing a blue band) in order to ensure a colour display along a column of the screen.
Each intersection of a grid 16 and a cathode conductor 12 in this embodiment corresponds to a monochromatic pixel. A "colour"
pixel is formed by three red, green and blue monochromatic pixels. me association of these three primary colours (red, green and blue) enables the eye to reconstitute a wide coloured spectrum.
A matrix screen having e.g. 575 rows and 720 columns (French television standard) corresponds to a microdot fluorescent screen with 575 grids and 720 x 3 = 2160 cathode conductors.
Fig. 2 diagrammatically shows a section of a trichromatic screen extrapolated from a monochromatic screen. The first substrate 10 and second substrate 22 are bonded with the aid of a fusible glass joint 25 in order to form a cell, which is under a vacuum for a satisfactory operation of the screen.
Fig. 2 shows the cathode conductors 12 separated from the grids 16 by an insulating layer 18. The cathode conductors 12 face red, green and blue phosphor bands 24, tha microdots not being sh~wn.
,, ~319~
The width L of a cathode conductor and the facing band 24 i approximately 100 micrometres. The distance D separating two cathode conductors 12 (and therefore two bands 24) is approximately 50 micrometres. The distance G between the cathode conductors 12 and the anode 20 is approximately 150 micrometres (the latter distance corresponding rou~hly to the thickness of the cement joint 25 located between ~he two substrates~.
The two substrates 10 and 22 are sealed hot ~at a temperature of approximately 400C) by melting and crushing a fusible glass rod.
In order toensure satisfactory operation, a precise positioning in facing manner of the parallel red, green and blue phosphor bands 24 and the cathode conductors 12 associated therewith is necessary. In practice, the maintaining of the positioning of the two substrates 10, 12 facing one another is very difficult during sealing. As the G/D ratio increases, this difficulty becomes more marked.
A similar problem has been solved for liquid crystal colour display cells. However, in the case of the latter, the equivalent thickness G between the two substrates is only 5 micrometres (instead of 150 micrometres for the microdot screen) for the same resolution of the patterns and the same required positioning precision. In addition, sealin~ takes place at low temperature by cement joints hardened by W light irradiation follo~ing positioning and prior to the stoving of the seal. The use of this type of bond or cement joint is not possible in the case of microdot screens. mus, the cements give off vapours, which would break the vacuum of the cell. It is not possible to carry out positioning prior to the hardening of the cement due to the high temperature necessary for melting and crushing the ~, ., 131 ~8~
fusible or meltable glass.
As compared with a microdot monochromatic fluorescent screen for a trichromati~ screen the number of cathode conductors is multipliedby three. Additional costs result from ~he increased number of addressing circuits of the cathode con~uctors.
m e present invention makes it possible to produce a microdot trichromatic fluorescent screen not requiring a precise positioning between two substrates 10, 22. Moreover, the invention makes it possible to reduce the number of control circuits (which is divided by three) of the cathode conductors by only adding three additional addressing circuits for the anode electrodes.
The invention recommends the use of three anodes (one for red, one for green and the other for blue). At a giYen instant, one of these anodes only is raised to a sufficiently high potential to attract the electrons emitted by the microdots. The two other anodes are raised to a po~ential such that the electrons emitted are repelled.
In an apparatus according to the in~en~ion, the arrangement on the substrate lQ of ca~hode conductors 12, grids 16 and the interposed insulant 18 is the same as for monochromatic screens.
Fig. 3 diagrammatically shows in perspective a screen according to ~he invention. On a first e.g. glass substrate 10 are provided along the columns cathode conductors 12 of I.T.O.
(indium tin oxide), e.g. supporting the microdots 14, along the rows e.g. niobium grids 16 separated from the cathode conductors 12 by an insulating material and e.g. silica layer 18. m is first part of the apparatus is identical to that used in the monochromatic screens.
1 3~ 9389 On a second e.g. glass substrate 22 are arranged regularly spaced, parallel conductive bands 26, which are represented diagonallly with respect to the direction of the cathode conductors 12 in order to clearly show that no positioning is required in this type of screen. It is obviously advantageous to place the bands 26 substantially facing the cathode conductors 12 and in a para-llel direction. These bands 26 are alternately covered, for a first series of said bands 26, by a material 28 able to emdt luminescence in the red, whereby said material 28 can be europium-doped Y202S; for a second series of said bands 26, by a material 29 able to emit luminescence in the green, whereby said material 29 can be CuAL-doped ZnS; and for a third series of said bands 26, by a material 30 able to emit luminescence in the blue, where-by said material 30 can be Ag-doped 7,nS.
Preferably, the conductive bands 26 are spaced in such a way that a red, green and blue triplet is superimposed at each inter-section by a cathode conductor 12 and a grid 16.
The conductive bands 26 of the first series covered with material 28 are electrically interconnected by a first connection band 32 indicated in fig. 3 by a connecting wire. This first series of bands 26 corresponds to an anode Al. The conductive bands 26 of the second series covered by material 29 are electrically interconnected by a second connection band 34 indicated in fig.
3 by a connecting wire. This second series of conductive bands 26 corresponds to an anode A2. The conductive bands 26 of the third series covered by material 30 are electrically interconn-ected by an anisotropic conductive ribbon or tape 36 indicated in fig. 3 by a connecting wire. Said third series of conductive bands 26 corresponds to an anode A3.
The spacing between the conductive bands 26 corresponds with the pass band of the video chrominance signal (approximately 150 micrometres for a 1 dm2 screen). The number of cathode cond-uctors 12 corresponds to the pass band of the video luminosity B 9678.3 PM
signal (approximately 500 cathode conductors for a pass band of approximately 3 MHz).
Fig. 4A indicates the manner in which the different conductive bands 26 are interconnected in a preferred embodiment. These bands 26 are etched in a conductive material, e.g. I.TØ covering the substrate 22. For two series of said bands 26, etching simul-taneously takes place in the same conductive mat~rial of the connection bands 32,34, each placed at one end of the conductive bands 26. These two series assume the form of combs arranged in head to tail manner. The teeth of one of the combs alternate with those of the other comb and then with the conductive bands 26 of the third series. These conductive bands 26 of the third series are electrically interconnected by an anisotropic conduc-tive ribbon 36, which is deposited perpendicular to the conductive bands 26, Fig. 4B shows a section of the screen along the anisotropic cond-uctive ribbon 36. The latter is essentially formed by a conduc-tive strip 36" and a film 36'.
As can be seen in fig. 4B the conductive strip 36" crushes the film 36' via extra thicknesses of the strip positioned facing the bands 26 of the third series. The film 36' comprises cond-uctive carbide balls 37 distributed in an insulating binder for-ming the film 36', so as not to conduct electricity. The density of the balls 37 is such that at the crushed points the balls 37 are in contact, the tape or ribbon becoming conductive at these points. Thus, the conductive bands 26 of the third series ~are electrically connected to the conductive strip 36", whereas the non-crushed locations of film 36' are insulating.
As can be seen in fig. 5, the use of anisotropic conductive ribb-ons can be extended to the first and second connection bands 32,34.
B 9678.3 PM
13~38~
Fig. 6 diagrammatically shows a section of a screen according to the invention. During the exciting of a pixel corresponding to the intersection of a cathode conductor 12 and a grid 16, the microdots 14 emit electrons. If anode Al ~respectively A2,A3 corresponding to the conductive bands 26 covered by the material 28 luminescing in the red is addressed, the anodes A2 (or Al,A3) and A3 (or Al,A2) are raised to potentials such that the electrons are repelled. Thus, no matter what the positioning of th~ cond-uctive bands 26, the "dilution" of the colours due to a parasitic excitation of the anodes A2 (or Al,A3) and A3 (or Al,A2) is avoi-ded. Obviously the phenomenon is the same when anodes A2 and A3 are addressed.
A screen according to the invention makes it possiblP to divide by three the number of control circuits for the cathode conductors 12 compared with the number of such circuits required in the case of a trichromatic screen simply extrapolated from a mono-chromatic screen. This appreciable gain and this simplification of ~he control circuitry o~ly requires three additional addressing circuits for the anodes Al, A2 and A3.
Hereinafter are given two non-limitative embodiments of processes for addressing a triple anode screen according to the invention.
First example of addressing signals for the screen according to the invention.
This first addressing method is shown in fig. 7. According to this first addressing method, a colour picture is produced as a result of three successive scans or sweeps of the screen corr-eaponding to three red, green and blue subframes.
The display of a trichromatic frame of the image takes place during a frame time T. The anodes Al, A2 and A3 are respectively raised to potentials VAl, VA2 and VA3. Successively and , B 9678.3 PM
131 ~38~
periodically, potentials VAl, VA2 and VA3 assume values VAlmax, VA2max and VA3max adequate for attracting the electrons emitted by the microdots 14 of the cathode conductors 12 corresponding to the pixels which have to be "illuminsted" in the colour of the considered anode Al, A2 or A3.
Potentials VAl, VA2 and VA3 assume their values VAlmax, VA2max and VA3max with a period equal to the frame time T. The latter is divided into three periods tl, t2 and t3 during which the potentials VAl, VA2 and VA3 are maintained at the values VAlmax, VA2max and VA3max.
The values VAlmax, VA2max and VA3max and the durations tl, t2 and t3 are adapted to the respective efficiencies of the lumin-escent materials 28,29 and 30. These values are experimentally adjus~ed in such a way that the saturation of the luminescent materials 28,29,30 gives a pure white when all the pixels of the screen and all the colours are "illuminated", said measure being averaged over several frames of the picture, VAlmax, VA2max and VA3max being e.g. approximately lOOV.
In this example of the addressing process, the three periods tl, t2 and t3 correspond to subframes of the picture during which are successively displayed the three monochromatic components red, green and blue of said picture. Outside the periods during which they are raised to VAlmax, VA2max and VA3max, the potentials VAl, VA2 and VA3 re~pec~ively assume the values YAlmin, VA2min and VA3min. These values are such that the electrons emitted by the microdots 14 are repelled or received by the anodes with energies below the threshold luminescence energies of the mater-ials 28,29 and 30.
Fig. 7 shows the potential VGi to which the grid i is raised.
Periodically VGi assumes the value VGmax equal to e.g. 40V during the grid selection times tGl, tG2 and tG3. tGl is the grid B 9678.3 PM
~ 3 ~
selection time during which VGi=VGmax, said addressing taking place during the subframe time tl, tG2 being the grid selection time during which VGi=VGmax, said addressing taking place during the subframe time t2, and tG3 i5 the grid selection time during which VGi=VGmax during the subframe time t3. Outside these periods tG1, tG2 and tG3, VGi assumes the value VGmin equal to e.g. -40V. The period of these successive square wave pulses of duration tGl, tG2 and tG3 is equal to a frame time T.
The durations tGl, tG2 and tG3 are linked with the durations tl, t2 and t3 by the relation:
tl t2 t3 = _ = _ = N
t51 tG2 tG3 in which N is equal to the number of lines of the screen.
Fig. 7 gives the control signals VCj of the cathode conductor j making it possible to "illumina~e" the pixel ij. These control signals VCj are given in the three following cases:
timing diagram Cl : pixel ij illuminated in red;
timing diagram C2 : pixel ij illuminated in red, green and blue and pixel ij being "white";
; timing diagram C3 : pixel ij extinguished and "black" state.
For the pixel ij to be "extinguished" (i.e. in a black state), potential VCj assumes a value VCmax equal to e.g. OV. In order to "illuminate" the pixel ij (timing diagram Cl) in red (respect-ively green or blue), VCj is raised to a value VCmin equal toe.g. -40V for the grid selection time tGl (respectively tG2, tG3).
In order to l'illuminate" the pixel ij in the three primary colours B 9678.3 PM
~31938~
red, green and blue (i.e. to obtain a "white" state) (timing diagram C2), potential VCj assumes the value VCmin for the grid selection times tGl, tG2 and tG3 in the three colours. With pixel ij extinguished ("black" state) (~iming diagram C3~, poten-tial VCj is maintained at the value VCmax for the selection timestGl, tG2 and tG3.
The line or row selection potential VGmax is chosen in such a way that the electron emission is substantially zero when the potential YCmax is applied to the cathode conductor and corr-esponds to the maximum desired brightness of the screen (e.g.200 cd/m2), when the potential VCmin is applied to the cathode conductor.
Numerical data correeponding to this example:
N : number of lines = 575 15 T : frame time = 20 ms tl : selection time of anode Al (subframe 1) = 6.6 ms t2 : selection time of anode A2 (subframe 2) = 6.6 ms t3 : selection time of anode A3 (subframe 3) = 6.6 ms tGl : selection time of a line during subframe 1 = 11 ys 20 tG2 : selection time of a line during subframe 2 = 11 ,us tG3 : selection time of a line during subframe 3 = 11 ys VAl : potential of anode Al = VAlmax = lOOV, VAlmin = 40V
VA2 : potential of anode A2 = VA2max = lOOV, VA2min = 40V
VA3 : potential of anode A3 = VA3max = 150V, VA3min = 40V
25 VGi : potential of grid i = VGmax = 40V, VGmin = -40V
VCj : potential of cathode conductor j = VCmax = OV, VCmin =-40V.
Second example of signals for addressing the screen according to the invention.
This second addressing method is shown in fig. 8 and according B 9678.3 PM
~3~9389 to it a colour picture is produced through the writing of each of the three primary colours red, green and blue row by row.
Conventionally, each row i (grid) is addressed for a 8rid selec-tion time t, i.e. at the period T of the frame time, the potential VGi assuming the value VGmax for a duration T and otherwise VGi is equal to VGmin.
The anodes Al, A2 and A3 are raised respectively to potential~
VAl, YA2 and VA3. Periodically (at period t, row selection time), VAl, VA2 and VA3 successively assume the values VAlmax, VA2max and VA3max for respective times 91, 02 and 03. They otherwise assume the values VAlmin, VA2min and VA3min. The duration ~1, ~2 and 03 are linked with the grid selection time t by the rela-tion:
t = ~ 2 + ~3 Obviously the grid selection time is linked with the frame time T by the relation:
t N
in which N is the number of lines of the screen.
Fig. 8 also shows the control signals VCj of the cathode cond-uctor j making it possible to "illuminate" the pixel ij, which is "extinguished" ("black" state), potential VCj assuming a valu~
VCmax equal to e.g. OV.
;
; 25 The control signals VCj are given in the three ~ollowing cases:
Timing diagram C4 : pixel ij illuminated in red Timing diagram C5 : pixel ij illuminated in red, green and blue and pixel ij "white"
I
9678.3 PM
1319~8~
Timing diagram C6 : pixel ij extinguished and "black".
The timing diagram C4 describes the potential VCj during the addressing of the cathode conductor j making it possible to "illuminate" pixel ij in red (respectively green or blue). For duration 01 (respectively 02, 03) for the addressing of the red anode A1 (respectively green A2 or blue A3), VCj assumes the value VCmin7 VCj being equal to VCmax for the remainder of the selection time of row i.
Timing diagram C5 describes the potential VCj during the address-ing of the cathode conductor j making it possible to "illuminate"
pixel ij in red, green and blue, i.e. obtain a "white" state for pixel ij. In this case, VCj i9 raised to VCmin for the comp-lete selection time t of row i.
Timing diagram C6 describes the potential VCj during the address-ing of the cathode conductor j in the case where pixel ij is "extinguished". In this case VCj is maintained at the ~alue VCmax for the selection time t of row i.
Numerical data corresponding to this example:
N : number of lines = 575 T : frame time = 20 ms t : selection time of a row (grid) 33 ,us al selection time of anode Al = 11 ys 02 : selection time of anode A2 = 11 ~s ~3 : selection time of anode A3 = 11 ,us 25 VAl : potential of anode Al = VAlmax = 100V, VAlmin = 40V
VA2 : potential of anode A2 = VA2max = lOOV, YA2min = 40V
VA3 : potential of anode A3 = VA3max = 150V, VA3min = 40V
VGi : potential of grid i = VGmax = 40V, VGmin = -40V
VCj : potential of cathode conductor j = VCmax = OV, VCmin = -40V.
IB 9678.3 PM
The present invention relates to a microdot trichromatic fluorescent screen, its addressing process and its production process. This type of screen is more particularly used in the colour display of fixed or moving images or pictures.
me known microdot ~luorescent screens are monochromatic, a description being provided in the report of the "Japanese Display 86 Congress"; p. 512 or in French patent application published under No. 2, 568,394 on January 31, 1986. The procedure used for monochromatic screens can be extrapolated to trichromatic screens.
More specifically, the present invention relates to a microdot trichromatic fluorescent screen having a first substrate on ~hich are arranged in the two directions of the matrix conductivecolumns (cathodeconductors) supportingthemicrodots and above the columns perforated conductive rows (grids), the rows and columns being separated by an insulating layer having apertures permitting the passage of the microdots, each intersection of a row and a column corresponding to a pixel.
On a second substrate facing the first, said screen has regularly spaced, parallel conductive bands, which are alternately covered by a material luminescing in the red (these bands forming a so-called red anode), a material luminescing in the green (these bands forming a so-called green anode) and a material luminescing in the blue (these bands forming a so-claled blue anode), the conductive bands covered by the same luminescent material being electrically interconnected.
m is arrangement of three anodes in comb-like configuration on the second substrate makes it possible to overcome any positioning problem. For example, ~he conductive bands of the anodes are placed substantially in the same direction as the .,'' -~
131~389 cathode conductors, three successive red, green and blue bands advantageously facing a cathode conductor.
As the conductive bands can obviously assume any direction with respect to that of the cathode conductors. Moreover, the number of conductive bands is independent of the number of cathode conductors. Preferably, the number of conductive bands is greater than three times the number of cathode conductors in order to ensure a better visual fusion of the colour.
The presen~ invention also relates to a process for addressing a microdot trichromatic fluorescent screen. This process consists of successively raising the anodes Ai, i ranging from 1 to 3, periodically to a potential VAimax adequate for attracting the electrons emitted by the microdots of the cathode conductors corresponding to the pixels which are to be "illuminated/switched on" in the colour of the considered anode Ai. When they are not raised to th~ potential VAimax, the anodes Ai are raised to a potential VAimin, such that the electrons emitted by the microdots are repelled or have an energy below the threshold cathodoluminescence energy of the luminescent materials covering the anodes Ai.
In a first preferred embodiment, the display of a trichromatic field or frame of the image takes place during a frame time T, the anodes Ai being raised to the potential VAimax for a period equal to the frame time T, the latter being divided into three times tl, t2 and t3 corresponding to the times during which the anodes Al, A2 and A3 are raised to the potentials VAlmax, VA2max and VA3max.
In a second preferred embodiment, the display of a trichromatic frame of the image takes place by sequentially addressing each row of the grid conductor for a selection time t, the anodes Ai being raised to the potential VALmax for a period equal to the 3 8 ~
selection time t, the latter being divided into three periods ~ 2 and ~3 corresponding to the times during which the anodes Al, A2 and A3 are raised to the potentials V~lmax, ~A2max and VA3max.
In these embodiments of the proces~, the three colours are never displayed at the same time. The colour sensation on a broad spectrum perceived by an observer of the screen is due to a reconstitution of the coloured spectrum by the viewer's eye.
The eye is a "slow" detector compared with the screen frame time and the perception of the full colour is due to an aYeraging effect over several frames of the image or picture.
m e present invention also rela~es to a process for the production of a microdot trichromatic fluorescent screen. This production process comprises covering the second substrate with a conductive material, etc~ing in said material regularly spaced, parallel bands, which are alternately grouped into three series, a first series of said bands being electrically connected by a first conductive material connection band, the latter being perpendicular to the parallel bands and is placed at one of the ends thereof, a second series of said parallel bands being electrically connected by a second conductive material connection band, the lat~er being perpendicular to the parallel bands and placed at the other end thereof, electrically interconnecting the third series of parallel bands by an anisotropic conductive ribbon or tape and covering a series of parallel bands by a material able to emit luminescence in the red, a second series of parallel bands by a material able to emit luminescence in the blue and the final series of parallel bands by a material able to emit luminescence in the green.
The conductive material of the first and second connection bands can be the same as that of the parallel bands~
/J, , 8 ~
In a variant of the production process, the first and second connection bands are anisotropic conductive ribbons.
Other features and advantages of the invention can be gathered from the following non-limitative description with reference to the drawings, wherein show:
Fig. 1 illustrates diagrammatically and in perspective a trichromatic screen extrapolated from a monochromatic screen.
Fig. 2 illustrates diagrammatically a section of a trichromatic screen extrapolated from a monochromatic screen.
Fig. 3 diagrammatically and in perspective a screen according to the invention.
Fig. 4 diagrammatically a connection method between the conductive bands.
Fig. 5 diagrammatically another connection method between the conductive bands.
Fig. 6 diagrammatically a section of a screen according to the invention.
Fig. 7 the timing charts relating to a first process for addressing a screen according to the invention.
Fig. 8 the timing charts relating to a second process for addressing a screen according to the invention.
Fig. 1 diagrammatically shows in perspective a trichromatic screen which could be extrapolated from a monochromatic screen.
On a first e.g. glass substrate 10 are arranged conductive columns 12 (cathode conductors) supporting metal microdots 14.
The columns intersect perforated conductive rows 15 (grids).
All the microdots 14 positioned at an intersection of a row and a column have their apex substantially facing a perforation of the row. Cathode conductors 12 and grids 16 are separated by an e.g. silica insulating layer 18, which has openings or apertures s. ,~^3~
13193~
permitting the passage of the microdots 14.
A layer 20 of conductive material (anode) is deposited on a second transparent, e.g. glass substrate 22. Parallel bands 24 alternately in red, green and blue phosphor are deposited on the anode 20 facing the ca~hode conductors 12. The bands can be replaced by a mosaic pattern.
In this con*iguration, it is necessary to have a triplet of cathode conductors 12 (one facing a red band, another facing a green band and another facing a blue band) in order to ensure a colour display along a column of the screen.
Each intersection of a grid 16 and a cathode conductor 12 in this embodiment corresponds to a monochromatic pixel. A "colour"
pixel is formed by three red, green and blue monochromatic pixels. me association of these three primary colours (red, green and blue) enables the eye to reconstitute a wide coloured spectrum.
A matrix screen having e.g. 575 rows and 720 columns (French television standard) corresponds to a microdot fluorescent screen with 575 grids and 720 x 3 = 2160 cathode conductors.
Fig. 2 diagrammatically shows a section of a trichromatic screen extrapolated from a monochromatic screen. The first substrate 10 and second substrate 22 are bonded with the aid of a fusible glass joint 25 in order to form a cell, which is under a vacuum for a satisfactory operation of the screen.
Fig. 2 shows the cathode conductors 12 separated from the grids 16 by an insulating layer 18. The cathode conductors 12 face red, green and blue phosphor bands 24, tha microdots not being sh~wn.
,, ~319~
The width L of a cathode conductor and the facing band 24 i approximately 100 micrometres. The distance D separating two cathode conductors 12 (and therefore two bands 24) is approximately 50 micrometres. The distance G between the cathode conductors 12 and the anode 20 is approximately 150 micrometres (the latter distance corresponding rou~hly to the thickness of the cement joint 25 located between ~he two substrates~.
The two substrates 10 and 22 are sealed hot ~at a temperature of approximately 400C) by melting and crushing a fusible glass rod.
In order toensure satisfactory operation, a precise positioning in facing manner of the parallel red, green and blue phosphor bands 24 and the cathode conductors 12 associated therewith is necessary. In practice, the maintaining of the positioning of the two substrates 10, 12 facing one another is very difficult during sealing. As the G/D ratio increases, this difficulty becomes more marked.
A similar problem has been solved for liquid crystal colour display cells. However, in the case of the latter, the equivalent thickness G between the two substrates is only 5 micrometres (instead of 150 micrometres for the microdot screen) for the same resolution of the patterns and the same required positioning precision. In addition, sealin~ takes place at low temperature by cement joints hardened by W light irradiation follo~ing positioning and prior to the stoving of the seal. The use of this type of bond or cement joint is not possible in the case of microdot screens. mus, the cements give off vapours, which would break the vacuum of the cell. It is not possible to carry out positioning prior to the hardening of the cement due to the high temperature necessary for melting and crushing the ~, ., 131 ~8~
fusible or meltable glass.
As compared with a microdot monochromatic fluorescent screen for a trichromati~ screen the number of cathode conductors is multipliedby three. Additional costs result from ~he increased number of addressing circuits of the cathode con~uctors.
m e present invention makes it possible to produce a microdot trichromatic fluorescent screen not requiring a precise positioning between two substrates 10, 22. Moreover, the invention makes it possible to reduce the number of control circuits (which is divided by three) of the cathode conductors by only adding three additional addressing circuits for the anode electrodes.
The invention recommends the use of three anodes (one for red, one for green and the other for blue). At a giYen instant, one of these anodes only is raised to a sufficiently high potential to attract the electrons emitted by the microdots. The two other anodes are raised to a po~ential such that the electrons emitted are repelled.
In an apparatus according to the in~en~ion, the arrangement on the substrate lQ of ca~hode conductors 12, grids 16 and the interposed insulant 18 is the same as for monochromatic screens.
Fig. 3 diagrammatically shows in perspective a screen according to ~he invention. On a first e.g. glass substrate 10 are provided along the columns cathode conductors 12 of I.T.O.
(indium tin oxide), e.g. supporting the microdots 14, along the rows e.g. niobium grids 16 separated from the cathode conductors 12 by an insulating material and e.g. silica layer 18. m is first part of the apparatus is identical to that used in the monochromatic screens.
1 3~ 9389 On a second e.g. glass substrate 22 are arranged regularly spaced, parallel conductive bands 26, which are represented diagonallly with respect to the direction of the cathode conductors 12 in order to clearly show that no positioning is required in this type of screen. It is obviously advantageous to place the bands 26 substantially facing the cathode conductors 12 and in a para-llel direction. These bands 26 are alternately covered, for a first series of said bands 26, by a material 28 able to emdt luminescence in the red, whereby said material 28 can be europium-doped Y202S; for a second series of said bands 26, by a material 29 able to emit luminescence in the green, whereby said material 29 can be CuAL-doped ZnS; and for a third series of said bands 26, by a material 30 able to emit luminescence in the blue, where-by said material 30 can be Ag-doped 7,nS.
Preferably, the conductive bands 26 are spaced in such a way that a red, green and blue triplet is superimposed at each inter-section by a cathode conductor 12 and a grid 16.
The conductive bands 26 of the first series covered with material 28 are electrically interconnected by a first connection band 32 indicated in fig. 3 by a connecting wire. This first series of bands 26 corresponds to an anode Al. The conductive bands 26 of the second series covered by material 29 are electrically interconnected by a second connection band 34 indicated in fig.
3 by a connecting wire. This second series of conductive bands 26 corresponds to an anode A2. The conductive bands 26 of the third series covered by material 30 are electrically interconn-ected by an anisotropic conductive ribbon or tape 36 indicated in fig. 3 by a connecting wire. Said third series of conductive bands 26 corresponds to an anode A3.
The spacing between the conductive bands 26 corresponds with the pass band of the video chrominance signal (approximately 150 micrometres for a 1 dm2 screen). The number of cathode cond-uctors 12 corresponds to the pass band of the video luminosity B 9678.3 PM
signal (approximately 500 cathode conductors for a pass band of approximately 3 MHz).
Fig. 4A indicates the manner in which the different conductive bands 26 are interconnected in a preferred embodiment. These bands 26 are etched in a conductive material, e.g. I.TØ covering the substrate 22. For two series of said bands 26, etching simul-taneously takes place in the same conductive mat~rial of the connection bands 32,34, each placed at one end of the conductive bands 26. These two series assume the form of combs arranged in head to tail manner. The teeth of one of the combs alternate with those of the other comb and then with the conductive bands 26 of the third series. These conductive bands 26 of the third series are electrically interconnected by an anisotropic conduc-tive ribbon 36, which is deposited perpendicular to the conductive bands 26, Fig. 4B shows a section of the screen along the anisotropic cond-uctive ribbon 36. The latter is essentially formed by a conduc-tive strip 36" and a film 36'.
As can be seen in fig. 4B the conductive strip 36" crushes the film 36' via extra thicknesses of the strip positioned facing the bands 26 of the third series. The film 36' comprises cond-uctive carbide balls 37 distributed in an insulating binder for-ming the film 36', so as not to conduct electricity. The density of the balls 37 is such that at the crushed points the balls 37 are in contact, the tape or ribbon becoming conductive at these points. Thus, the conductive bands 26 of the third series ~are electrically connected to the conductive strip 36", whereas the non-crushed locations of film 36' are insulating.
As can be seen in fig. 5, the use of anisotropic conductive ribb-ons can be extended to the first and second connection bands 32,34.
B 9678.3 PM
13~38~
Fig. 6 diagrammatically shows a section of a screen according to the invention. During the exciting of a pixel corresponding to the intersection of a cathode conductor 12 and a grid 16, the microdots 14 emit electrons. If anode Al ~respectively A2,A3 corresponding to the conductive bands 26 covered by the material 28 luminescing in the red is addressed, the anodes A2 (or Al,A3) and A3 (or Al,A2) are raised to potentials such that the electrons are repelled. Thus, no matter what the positioning of th~ cond-uctive bands 26, the "dilution" of the colours due to a parasitic excitation of the anodes A2 (or Al,A3) and A3 (or Al,A2) is avoi-ded. Obviously the phenomenon is the same when anodes A2 and A3 are addressed.
A screen according to the invention makes it possiblP to divide by three the number of control circuits for the cathode conductors 12 compared with the number of such circuits required in the case of a trichromatic screen simply extrapolated from a mono-chromatic screen. This appreciable gain and this simplification of ~he control circuitry o~ly requires three additional addressing circuits for the anodes Al, A2 and A3.
Hereinafter are given two non-limitative embodiments of processes for addressing a triple anode screen according to the invention.
First example of addressing signals for the screen according to the invention.
This first addressing method is shown in fig. 7. According to this first addressing method, a colour picture is produced as a result of three successive scans or sweeps of the screen corr-eaponding to three red, green and blue subframes.
The display of a trichromatic frame of the image takes place during a frame time T. The anodes Al, A2 and A3 are respectively raised to potentials VAl, VA2 and VA3. Successively and , B 9678.3 PM
131 ~38~
periodically, potentials VAl, VA2 and VA3 assume values VAlmax, VA2max and VA3max adequate for attracting the electrons emitted by the microdots 14 of the cathode conductors 12 corresponding to the pixels which have to be "illuminsted" in the colour of the considered anode Al, A2 or A3.
Potentials VAl, VA2 and VA3 assume their values VAlmax, VA2max and VA3max with a period equal to the frame time T. The latter is divided into three periods tl, t2 and t3 during which the potentials VAl, VA2 and VA3 are maintained at the values VAlmax, VA2max and VA3max.
The values VAlmax, VA2max and VA3max and the durations tl, t2 and t3 are adapted to the respective efficiencies of the lumin-escent materials 28,29 and 30. These values are experimentally adjus~ed in such a way that the saturation of the luminescent materials 28,29,30 gives a pure white when all the pixels of the screen and all the colours are "illuminated", said measure being averaged over several frames of the picture, VAlmax, VA2max and VA3max being e.g. approximately lOOV.
In this example of the addressing process, the three periods tl, t2 and t3 correspond to subframes of the picture during which are successively displayed the three monochromatic components red, green and blue of said picture. Outside the periods during which they are raised to VAlmax, VA2max and VA3max, the potentials VAl, VA2 and VA3 re~pec~ively assume the values YAlmin, VA2min and VA3min. These values are such that the electrons emitted by the microdots 14 are repelled or received by the anodes with energies below the threshold luminescence energies of the mater-ials 28,29 and 30.
Fig. 7 shows the potential VGi to which the grid i is raised.
Periodically VGi assumes the value VGmax equal to e.g. 40V during the grid selection times tGl, tG2 and tG3. tGl is the grid B 9678.3 PM
~ 3 ~
selection time during which VGi=VGmax, said addressing taking place during the subframe time tl, tG2 being the grid selection time during which VGi=VGmax, said addressing taking place during the subframe time t2, and tG3 i5 the grid selection time during which VGi=VGmax during the subframe time t3. Outside these periods tG1, tG2 and tG3, VGi assumes the value VGmin equal to e.g. -40V. The period of these successive square wave pulses of duration tGl, tG2 and tG3 is equal to a frame time T.
The durations tGl, tG2 and tG3 are linked with the durations tl, t2 and t3 by the relation:
tl t2 t3 = _ = _ = N
t51 tG2 tG3 in which N is equal to the number of lines of the screen.
Fig. 7 gives the control signals VCj of the cathode conductor j making it possible to "illumina~e" the pixel ij. These control signals VCj are given in the three following cases:
timing diagram Cl : pixel ij illuminated in red;
timing diagram C2 : pixel ij illuminated in red, green and blue and pixel ij being "white";
; timing diagram C3 : pixel ij extinguished and "black" state.
For the pixel ij to be "extinguished" (i.e. in a black state), potential VCj assumes a value VCmax equal to e.g. OV. In order to "illuminate" the pixel ij (timing diagram Cl) in red (respect-ively green or blue), VCj is raised to a value VCmin equal toe.g. -40V for the grid selection time tGl (respectively tG2, tG3).
In order to l'illuminate" the pixel ij in the three primary colours B 9678.3 PM
~31938~
red, green and blue (i.e. to obtain a "white" state) (timing diagram C2), potential VCj assumes the value VCmin for the grid selection times tGl, tG2 and tG3 in the three colours. With pixel ij extinguished ("black" state) (~iming diagram C3~, poten-tial VCj is maintained at the value VCmax for the selection timestGl, tG2 and tG3.
The line or row selection potential VGmax is chosen in such a way that the electron emission is substantially zero when the potential YCmax is applied to the cathode conductor and corr-esponds to the maximum desired brightness of the screen (e.g.200 cd/m2), when the potential VCmin is applied to the cathode conductor.
Numerical data correeponding to this example:
N : number of lines = 575 15 T : frame time = 20 ms tl : selection time of anode Al (subframe 1) = 6.6 ms t2 : selection time of anode A2 (subframe 2) = 6.6 ms t3 : selection time of anode A3 (subframe 3) = 6.6 ms tGl : selection time of a line during subframe 1 = 11 ys 20 tG2 : selection time of a line during subframe 2 = 11 ,us tG3 : selection time of a line during subframe 3 = 11 ys VAl : potential of anode Al = VAlmax = lOOV, VAlmin = 40V
VA2 : potential of anode A2 = VA2max = lOOV, VA2min = 40V
VA3 : potential of anode A3 = VA3max = 150V, VA3min = 40V
25 VGi : potential of grid i = VGmax = 40V, VGmin = -40V
VCj : potential of cathode conductor j = VCmax = OV, VCmin =-40V.
Second example of signals for addressing the screen according to the invention.
This second addressing method is shown in fig. 8 and according B 9678.3 PM
~3~9389 to it a colour picture is produced through the writing of each of the three primary colours red, green and blue row by row.
Conventionally, each row i (grid) is addressed for a 8rid selec-tion time t, i.e. at the period T of the frame time, the potential VGi assuming the value VGmax for a duration T and otherwise VGi is equal to VGmin.
The anodes Al, A2 and A3 are raised respectively to potential~
VAl, YA2 and VA3. Periodically (at period t, row selection time), VAl, VA2 and VA3 successively assume the values VAlmax, VA2max and VA3max for respective times 91, 02 and 03. They otherwise assume the values VAlmin, VA2min and VA3min. The duration ~1, ~2 and 03 are linked with the grid selection time t by the rela-tion:
t = ~ 2 + ~3 Obviously the grid selection time is linked with the frame time T by the relation:
t N
in which N is the number of lines of the screen.
Fig. 8 also shows the control signals VCj of the cathode cond-uctor j making it possible to "illuminate" the pixel ij, which is "extinguished" ("black" state), potential VCj assuming a valu~
VCmax equal to e.g. OV.
;
; 25 The control signals VCj are given in the three ~ollowing cases:
Timing diagram C4 : pixel ij illuminated in red Timing diagram C5 : pixel ij illuminated in red, green and blue and pixel ij "white"
I
9678.3 PM
1319~8~
Timing diagram C6 : pixel ij extinguished and "black".
The timing diagram C4 describes the potential VCj during the addressing of the cathode conductor j making it possible to "illuminate" pixel ij in red (respectively green or blue). For duration 01 (respectively 02, 03) for the addressing of the red anode A1 (respectively green A2 or blue A3), VCj assumes the value VCmin7 VCj being equal to VCmax for the remainder of the selection time of row i.
Timing diagram C5 describes the potential VCj during the address-ing of the cathode conductor j making it possible to "illuminate"
pixel ij in red, green and blue, i.e. obtain a "white" state for pixel ij. In this case, VCj i9 raised to VCmin for the comp-lete selection time t of row i.
Timing diagram C6 describes the potential VCj during the address-ing of the cathode conductor j in the case where pixel ij is "extinguished". In this case VCj is maintained at the ~alue VCmax for the selection time t of row i.
Numerical data corresponding to this example:
N : number of lines = 575 T : frame time = 20 ms t : selection time of a row (grid) 33 ,us al selection time of anode Al = 11 ys 02 : selection time of anode A2 = 11 ~s ~3 : selection time of anode A3 = 11 ,us 25 VAl : potential of anode Al = VAlmax = 100V, VAlmin = 40V
VA2 : potential of anode A2 = VA2max = lOOV, YA2min = 40V
VA3 : potential of anode A3 = VA3max = 150V, VA3min = 40V
VGi : potential of grid i = VGmax = 40V, VGmin = -40V
VCj : potential of cathode conductor j = VCmax = OV, VCmin = -40V.
IB 9678.3 PM
Claims (8)
1. Matrix display microdot trichromatic fluorescent screen having a first substrate on which are arranged, in two directions of the matrix, conductor columns forming cathode conductors and supporting microdots and above the columns perforated conductive rows forming grids, the rows and columns being separated by an insulating layer having apertures permitting the passage of the microdots, each intersection of a row and a column corresponding to a pixel, said screen having on a second substrate facing the first, parallel, regularly spaced conductive bands, which form groups of three adjacent conductive bands, a material luminescing in the red forming a red anode A1 and covering a first band of each group, a material luminescing in the green forming a green anode A2 and covering a second band of each group and a material luminescing in the blue forming a blue anode A3 and covering a third band of each group, the conductive bands covered with the same luminescent material being electrically interconnected,said conductive bands being spaced in such a way that each intersection of a row and a column is facing a group of three adjacent conductive bands respectively covered with the materials luminescing in the red, the green and the blue.
2. Process for addressing a microdot trichromatic fluorescent screen according to claim 1, characterized in that it comprises raising the anodes A1, A2, A3 successively and periodically during respective preselected times to a potential respectively VA1max, YA2max, VA3max adequate for attracting the electrons emitted by the microdots of the cathode conductors corresponding to the pixels having to be "illuminated" in the colour of the considered anode ; and raising the anodes A1, A2, A3 at all other times to a potential respectively VA1min, VA2min, VA3min, such that the electrons emitted by the microdots are repelled.
3. Addressing process according to claim 2, the addressing of a trichromatic frame of the picture taking place during a frame time T, characterized in that the anodes A1, A2, A3 are raised to the potential VA1max, VA2max, VA3max for a period equal to the frame the T, which is subdivided into three periods t1, t2 and t3 corresponding to the times during which the anodes Al, A2 and A3 are raised to the potentials VA1max, VA2max and VA3max.
4. Addressing process according to claim 2, the display of a trichromatic frame of the picture taking place by sequentially addressing each grid conductor row for a selection time t, characterized in that the anodes A1, A2, A3 are raised to two potential VA1max, VA2max, VA3max for a period equal to the selection time t, which is subdivided into three periods .theta.1, .theta.2 and .theta.3 corresponding to the times during which the anodes A1, A2 and A3 are raised to the potentials VA1max, VA2max and VA3max.
5. Process for addressing a microdot trichromatic fluorescent screen according to claim 1, characterized in that it comprises raising the anodes A1, A2, A3, successively and periodically during respective preselected times to a potential respectively VA1max, VA2max, VA3max adequate for attracting the electrons emitted by the microdots of the cathode conductors corresponding to the pixels having to be "illuminated" in the considered colour of the anode ; and raising the anodes A1, A2, A3 at all other times to a potential VA1min, YA2min, VA3min, such that the electrons emitted by the microdot have an energy below the threshold cathodoluminescence energy of the luminescent materiels covering the anodes.
6. Addressing process according to claim 5, the addressing of a trichromatic frame of the picture taking place for a frame time T, characterized in that the anodes A1, A2, A3 are raised to the potential VA1max, YA2max, VA3max for a period equal to the frame tame T, which is subdivided into three durations t1, t2 and t3 corresponding to the times during which the anodes Al, A2 and A3 are raised to the potentials VA1max, VA2max and VA3max.
7. Addressing process according to claim 5, the display of a trichromatic frame of the picture taking place by sequentially addressing each grid conductor row for a selection time t, characterized in that the anodes A1, A2, A3 are raised to the potential VA1max, VA2max, VA3max for a period equal to the selection time t, which is subdivided into three durations .theta.1, .theta.2 and .theta.3 corresponding to the times during which the anodes A1, A2 and A3 are raised to the potentials VA1max, VA2max and VA3max.
8. Process for the production of a microdot trichromatic fluorescent screen according to claim 1, the second substrate being covered with a conductive material, characterized in that it comprises etching in said material regularly spaced, parallel bands, which are alternately grouped into three series, a first series of bands being electrically connected by a first conductive material connection band, which is perpendicular to the parallel bands and is placed at one of the ends thereof, a second series of the parallel bands being electrically connected by a second conductive material connection band, which is perpendicular to the parallel bands and is placed at the other of the ends thereof, electrically connecting the third series of parallel bands by an anisotropic conductive ribbon and covering one series of parallel bands by a material able to emit luminescence in the red, a second series of parallel bands by a material able to emit luminescence in the blue and the final series of parallel bands by a material able to emit luminescence in the green.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8808754 | 1988-06-29 | ||
| FR8808754A FR2633763B1 (en) | 1988-06-29 | 1988-06-29 | MICROPOINT TRICHROME FLUORESCENT SCREEN |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1319389C true CA1319389C (en) | 1993-06-22 |
Family
ID=9367860
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000604030A Expired - Fee Related CA1319389C (en) | 1988-06-29 | 1989-06-27 | Microdot trichromatic fluorescent screen |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0349425B1 (en) |
| JP (1) | JP2728739B2 (en) |
| KR (1) | KR0140537B1 (en) |
| CA (1) | CA1319389C (en) |
| DE (1) | DE68911403T2 (en) |
| FR (1) | FR2633763B1 (en) |
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| US6236381B1 (en) | 1997-12-01 | 2001-05-22 | Matsushita Electronics Corporation | Image display apparatus |
| US6278235B1 (en) | 1997-12-22 | 2001-08-21 | Matsushita Electronics Corporation | Flat-type display apparatus with front case to which grid frame with extended electrodes fixed thereto is attached |
| FR2786597B1 (en) * | 1998-11-27 | 2001-02-09 | Pixtech Sa | DIGITAL ADDRESSING OF A FLAT VISUALIZATION SCREEN |
| JP2005085728A (en) * | 2003-09-11 | 2005-03-31 | Toshiba Corp | Image display apparatus |
| JP4976787B2 (en) * | 2006-08-31 | 2012-07-18 | 株式会社ピュアロンジャパン | Field emission lamp |
| EP2472553B1 (en) * | 2010-12-28 | 2018-06-27 | LightLab Sweden AB | Field emission lighting arrangement |
Family Cites Families (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3036219A1 (en) * | 1980-09-25 | 1982-05-06 | Siemens Ag | Flat TV screen with cold cathode matrix - has bi-metal face column conductors with insulator separation from line conductors |
| JPS593469U (en) * | 1982-06-30 | 1984-01-10 | 株式会社日立製作所 | flat fluorescent display tube |
| DE3243596C2 (en) * | 1982-11-25 | 1985-09-26 | M.A.N. Maschinenfabrik Augsburg-Nürnberg AG, 8000 München | Method and device for transferring images to a screen |
| FR2561019B1 (en) * | 1984-03-09 | 1987-07-17 | Etude Surfaces Lab | PROCESS FOR PRODUCING FLAT VISUALIZATION SCREENS AND FLAT SCREENS OBTAINED BY IMPLEMENTING SAID METHOD |
| FR2568394B1 (en) * | 1984-07-27 | 1988-02-12 | Commissariat Energie Atomique | DEVICE FOR VIEWING BY CATHODOLUMINESCENCE EXCITED BY FIELD EMISSION |
| JPS62226546A (en) * | 1986-03-27 | 1987-10-05 | Nec Corp | Flat type color display |
-
1988
- 1988-06-29 FR FR8808754A patent/FR2633763B1/en not_active Expired - Lifetime
-
1989
- 1989-06-27 CA CA000604030A patent/CA1319389C/en not_active Expired - Fee Related
- 1989-06-28 DE DE68911403T patent/DE68911403T2/en not_active Expired - Lifetime
- 1989-06-28 EP EP89401852A patent/EP0349425B1/en not_active Expired - Lifetime
- 1989-06-29 JP JP1168282A patent/JP2728739B2/en not_active Expired - Lifetime
- 1989-06-29 KR KR1019890009382A patent/KR0140537B1/en not_active IP Right Cessation
Also Published As
| Publication number | Publication date |
|---|---|
| JP2728739B2 (en) | 1998-03-18 |
| FR2633763B1 (en) | 1991-02-15 |
| DE68911403T2 (en) | 1994-06-01 |
| JPH0261946A (en) | 1990-03-01 |
| FR2633763A1 (en) | 1990-01-05 |
| DE68911403D1 (en) | 1994-01-27 |
| EP0349425A1 (en) | 1990-01-03 |
| KR0140537B1 (en) | 1998-06-01 |
| KR900000956A (en) | 1990-01-31 |
| EP0349425B1 (en) | 1993-12-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |