US3796909A - Electroluminescent storage display - Google Patents

Electroluminescent storage display Download PDF

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Publication number
US3796909A
US3796909A US00263038A US3796909DA US3796909A US 3796909 A US3796909 A US 3796909A US 00263038 A US00263038 A US 00263038A US 3796909D A US3796909D A US 3796909DA US 3796909 A US3796909 A US 3796909A
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Prior art keywords
write
storage
layer
potential
gun
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US00263038A
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English (en)
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I Chang
W Pennebaker
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International Business Machines Corp
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International Business Machines Corp
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B33/00—Electroluminescent light sources
    • 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
    • H01J29/10—Screens on or from which an image or pattern is formed, picked up, converted or stored
    • H01J29/18—Luminescent screens
    • H01J29/182—Luminescent screens acting upon the lighting-up of the luminescent material other than by the composition of the luminescent material, e.g. by infra red or UV radiation, heating or electric fields
    • 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
    • H01J31/122—Direct viewing storage tubes without storage grid

Definitions

  • ABSTRACT A bistable storage and display tube using an electrolu- [52] U.S. Cl. 315/12, 313/92 R, 313/108 B, 1 bl f h 340/166 EL mmescent ayer capa e o storing an on c arge pattern, created by an electron write gun, on the mner [51] Int. Cl. H011 29/41 surface thereof.
  • An electron flood gun is employed to [58] Field of Search 315/1 313/92 clam the otential of the inner surface of the electro- 313/92 R, 108 R, 108 B; 340/166 EL P luminescent layer, in the on regions where a charge [56] References Cited pattern is created, to the potent1al of a collector elec' trode.
  • An a.c. signal applied to the electroluminescent UNITED STATES PATENTS layer, via a transparent conductive layer in contact 3,641,533 2/1972 Sylvander 340/166 EL X with the outer urface theregf acts to develop an 3,673,572 6/1972 Silva et a1.
  • the present invention relates to bistable storage and display devices, and more particularly to bistable storage and display tubes which utilize electroluminescence and cathodoluminescence to achieve bright storage display.
  • an improved bistable storage and display device is obtained by employing an electron flood gun to clamp the potential on the inner surface of display material, at those regions where the material is in an on state, to a fixed potential and to allow the potential on the inner surface of the display material at those regions where the material is in an off state to float with an a.c. voltage applied thereto.
  • a bistable storage and display tube exhibiting relatively high brightness and long life is obtained by using electroluminescence, in addition to possible cathodoluminescence, in an arrangement wherein an electroluminescent material is employed as the display surface, and has applied thereto an a.c. voltage.
  • the a.c. voltage creates an alternating field across the electroluminescent material to produce electroluminescence in on regions where the inner surface of the electroluminescent material is held at a fixed potential by an electron flood gun, in response to a charge pattern produced thereon by a high energy electron writing gun. In the off" regions where no charge pattern is formed, the electron flood gun has no effect thereon, and the a.c. voltage fails to produce an alternating field to cause electroluminescence thereat.
  • FIG. 1 shows a cross-section of the bistable storage and display tube, in accordance with the present invention.
  • FIG. 2 shows a plot of typical secondary electron emission ratio characteristics for the electroluminescent display material employed in FIG. 1.
  • FIG. 1 there is shown an embodied configuration of the electroluminescent storage and display tube, in accordance with the principles of the present invention.
  • the overall configuration of the storage tube shown in FIG. 1 is analogous to any of the variety of cathode ray type storage tubes, employed in the prior art.
  • conventional two gun cathodoluminescent bistable storage tubes employ a configuration and a structure, somewhat analogous to that shown in FIG. 1.
  • the layer of material shown at 1 is cathodoluminescent while in the arrangement, in accordance with the principles of the present invention, the layer of material at 1 is electroluminescent.
  • the arrangement shown in FIG. 1 employs a fine mesh 3 in front of electroluminescent material 1 and a conductive baclc plate 5, behind the electroluminescent material 1.
  • the arrangement in FIG. 1 utilizes the application of an a.c. voltage, via a.c. source 7 to the conductive plate 5.
  • storage tube 9 may comprise any of a variety of conventional storage tube materials and configurations. Typically, storage tube 9 would be made of glass.
  • the high energy electron writing gun shown at 11 comprises a conventional configuration, well known to those skilled in the art.
  • high energy electron source 13 acts to emit high energy electrons through focusing element 115 to the vertical and horizontal fields created by the deflection plates shown at l7, l9 and 21.
  • plates 17 and 19 act to vertically deflect the high energy electron beam while plate 21, V another plate not shown, acts to horizontally deflect the electron beam.
  • flood guns 23 and 25 acting through respective focusing elements 27 and 29, serve to flood the entire surface of electroluminescent layer 3 with relatively low energy electrons.
  • Flood guns 23 and 25 are coupled, as shown, to the negative side of respective power supplies 31 and 33, while the positive side of latter supplies are coupled to ground.
  • high energy electron source 13 is coupled to the negative side of power supply 35, while the positive side of latter supply is coupled to ground.
  • source 13 may be a two kv. high energy electron source.
  • d.c. supplies 31, 33 and 35 may, for example, be set at around 300 volts. However, it is clear that the value of these supplies is not critical, and accordingly, their values may be set anywhere within the range of from 1 to several hundred volts.
  • conductive mesh 3 is coupled to ground, and serves to act as the collector for the secondary emission electrons, given off by electroluminescent layer 1. It is understood, however, that this collector may comprise any configuration, such as a ring electrode arrangement, and may be fixed to any potential level, as long as the positive voltage difference relative to the cathode is maintained.
  • Electroluminescent layer ll may comprise any of a variety of well known electroluminescent materials.
  • layer 1 comprises an electroluminescent phosphor, in powder form, embedded in an inorganic dielectric binder.
  • layer 1 may comprise Cu doped ZnS uniformly mixed into a glass binder.
  • Exemplary of the electroluminescent materials that may be employed, and methods for fabricating same, are those described by Blazej et al. in U. S. Pat. No. 3,313,652.
  • An alternative scheme may be employed whereby an electroluminescent layer is coated with another layer having a high secondary emission ratio.
  • conductive layer 5, shown in FIG. 1, must nec essarily be of a transparent nature.
  • any of a variety of transparent conductors may be employed, such as, oxides of tin. indium or copper, or etched thin metal layers.
  • thin layers of copper iodide may be employed.
  • electroluminescent layer I may be deposited upon oxide layer 5, or vice-versa. With layers I and 5 mounted in the envelope of tube 9, the tube is finally sealed with transparent layer 37, which typically may be a relatively thick layer of glass.
  • electroluminescent material exhibits luminescence in response to an alternating field applied thereacross as known in the art.
  • an alternating field is applied to selected local re gions of electroluminescent layer 1, for purposes of bistable storage and display, by the utilization of the secondary emission characteristics of the electroluminescent material, and the action of the electron flood guns, as shown in FIG. ll.
  • alternating current source 7, designated V acts to apply an alternating field across electroluminescent layer 1 in those regions where writing gun 11 has created a charge pattern, in accordance with the information to be stored and displayed.
  • alternating current source 7 designated V acts to apply an alternating field across electroluminescent layer 1 in those regions where writing gun 11 has created a charge pattern, in accordance with the information to be stored and displayed.
  • the alternating current is developed across layer 1, luminescence is produced.
  • the regions in luminescent layer 1 where a luminescence condition exists corresponding to the regions where a charge pattern has been written, will be considered in the on" condition.
  • the on condition corresponds to the high potential equilibrium condition of the device.
  • the non-luminescent condition will be con sidered the off condition, or the low potential equilibrium state.
  • alternating fields are produced across luminescent layer l at regions in the on" condition by clamping the charged surface thereof to the potential of collector electrode 3, via the flood gun beams.
  • Those regions of electroluminescent layer 1 which are uncharged are in the low potential equilibrium state having no flood beam landing, and are thus free to float with potential variations in the alternating current source 7, as will be described below.
  • do source 39 V is to bias electroluminescent layer 1 so as to prevent leakage current and breakdown.
  • source 39 is selected so as to establish an operating point for layer 1 so that the potential variations thereon will not swing into the breakdown regions thereof.
  • FIG. 2 shows the typical electron emission characteristics as a function of electron energy, for conventional electroluminescent phosphors.
  • the horizontal straight line across the characteristic curve corresponds to 6 l, where 8 is the ratio of electrons coming away from the material to the electrons going into the material.
  • the electrons coming away from the material are considered the sum of the two secondary electrons plus any back scattered or reflected electrons.
  • the electron energy is O or negative, corresponding to the region to the left-hand of the ordinate, 8 I.
  • This ratio implies that all electrons entering the vicinity of the material do not have sufficient energy to enter therein to produce secondary electrons, but are rather scattered or reflected on a lzl basis. This corresponds to a condition of equilibrium, and as designated in FIG.
  • V At 0 electron energy, a low potential equilibrium condition exists, designated V
  • V As the electron energy increases from 0 potential at V the ratio 5 declines. This declination indicates that more electrons are entering the electroluminescent material than are being given off. Thus, the material is accumulating a charge. At V the ratio is unity and thereafter it can be seen that more electrons pass from than enter the material. This point is an unstable point since any deviation in electron energy would either charge down to V or charge up to V
  • the dotted line projecting from the peak of the characteristic curve between V and V represents the normal decline seen in the number of electrons coming away from the material, as the electron energy increases. As shown, a unity ratio is again seen at V
  • the solid line passing through V represents the effect of collector 3, adjacent electroluminescent material 1. Positioning collector 3 at this potential level has the effect of modifying the ratio in question to establish an equilibrium point at VEQQ.
  • collector electrode 3 is positioned adjacent electroluminescent layer 1 at a d.c. potential less than, but close thereto.
  • collector electrode 3 is positioned adjacent electroluminescent layer 1 at a d.c. potential less than, but close thereto.
  • Such a condition corresponds to the low potential equilibrium condition V as shown in FIG. 2. Since electroluminescent material 1 is not affected by the electron beam from the flood guns to give off secondary emission, the inner surface 1A thereof is electrically free to vary in potential in accordance with the potential applied to back plate 5. Thus, the potential of inner surface 1A of electroluminescent material 1 follows the potential of alternating voltage source 7, applied to plate 5. Under such a condition, no alternating field is effected across the electroluminescent material.
  • electroluminescent material 1 in its low voltage equilibrium condition V the alternating current source 7 initially commences to operate about the 0 potential ordinate, shown in FIG. 2.
  • electroluminescent material 1 is basically a dielectric
  • the charges accumulated on this and subsequent positive half cycles of the alternating current source tend to build up in the material.
  • This build up acts to produce a self-biasing effect, whereby after several cycles, a net negative d.c. bias equal to the peak voltage of the alternating current signal is produced in the material. Accordingly, with this self-biased condition produced, the alternating voltage source swings between 0 and some negative potential.
  • 8 in the negative electron energy region is l and no secondary electrons are produced.
  • writing gun 11 is initially employed to effect a desired charge pattern image on the inner surface 1A thereof.
  • this charge pattern image may comprise any of a variety of images, such as an array of alphanumeric characters.
  • the charge acts to attract electrons from flood guns 23 and 25.
  • the attracted electrons in turn, produce secondary electron emission which is collected by collector 3. Accordingly, at these charge locations, corresponding to the information written,
  • the electroluminescent material is at the high potential equilibrium condition corresponding to V shown in FIG. 2.
  • the effect of collector 3 collecting the electrons emitted from the electroluminescent material in the regions of the charge image, is to clamp the surface 1A in these regions to the potential of the collector, i.e., ground.
  • alternating voltage source 7 is able to produce an alternating current thereat. Accordingly, electroluminescence is generated in the electroluminescent material beneath the regions on surface 1A containing the charge pattern.
  • flood guns 23 and 25 are employed to clamp the surface 1A of electroluminescent material 1, at regions corresponding to the charge pattern written therein, whereby the alternating current applied to back plate 5 is allowed to develop across the electroluminescent material to produce luminescence.
  • the surface is allowed to vary in potential in accordance in which the manner in which the alternating current source 1 1 varies. These latter regions correspond to the of or low potential equilibrium condition of the electroluminescent material.
  • the writing gun 11 acts to produce a beam of much higher landing energy and current density than electrons from flood guns 23 and 25, whereby selected electroluminescent target elements are shifted positive above the first crossover V to V shown in FIG.
  • J can be shown to be greater than CV by choosing parameters and conditions as follows:
  • electroluminescent layer 1 in addition to obtaining electroluminescence at selected regions of electroluminescent layer 1, it is also possible to obtain at these same regions a certain amount of cathodoluminescence.
  • electroluminescent materials also exhibit cathodoluminescence.
  • electrons from the flood guns which are attracted to the selected regions, act to provide a certain amount of cathodoluminescence thereat.
  • cathodoluminescent material be deposited upon the inner surface 1A of electroluminescent material 1, whereby both electroluminescence and cathodeluminescence would be effected, in accordance with the principles of the present invention.
  • the electroluminescent material will have a limited life. Accordingly, in order to provide a replaceable electroluminescent layer, rather than replace the whole tube, it should be appreciated that the inner layer of the tube, corresponding to layer 1 in FIG. I, may comprise merely a secondary electron emissive material in a dielectric binder. With such an arrangement. an electroluminescent layer with contact- 6 be made between emissive layer 1 and the outer electroluminescent layer by an array of conductive feedthrough pins, through glass layer 37. Such an arrangement would be analagous to the metal pin arrangement described in the IBM Technical Disclosure Bulletin, Vol. 12, No. 12, May 1970, page 2324, in an article entitled Gas Discharge Display Device by D. M. Hart.
  • a cathode ray type storage display device having a higher energy electron write gun, electron flood gun means and a write surface means capable of retaining a charge pattern written by said write gun, the improvement comprising:
  • said write surface means to produce a visible change at selected points on the viewing surface thereof according to a charge pattern written by said write gun thereon, with said visible change occurring in response to an a.c. signal applied to the said selected points, said means included in said write surface means also acting to produce secondary electron emission at said selected points in response to electrons from said flood gun means entering said write surface means at said selected points according to said charge pattern;
  • means for applying an a.c. signal to said write surface means and collector electrode means positioned adjacent said write surface means for collecting the said secondary electrons emitted from said selected points and causing said selected points to become clamped in potential to the potential of said collector electrode means so as to cause said a.c. signal to be developed thereat to produce said visible change.
  • means included in said write surface means comprises electroluminescent material held in a dielectric binder to form an insulating layer at said write surface.
  • a storage display tube device comprising: storage means including a layer of storage material means having an inner write surface and an outer display surface thereof and being responsive at selected local regions on said inner surface to electrons provided thereto to produce secondary electron emission on at least the said inner surface thereof, said storage material means further being responsive to an a.c. signal applied to the said selected local regions thereof to produce a visible change on the said outer display surface thereof;
  • collector electrode means positioned adjacent the said inner surface of said storage material means for collecting electrons
  • electron write gun means for selectively writing a charge storage image pattern at said local regions on the said inner surface of said storage material means
  • electron flood gun means for flooding the said charge storage image pattern with electrons to cause said storage material means to produce secondary electron emission at said local regions and clamp the potential thereat to the potential of said collector electrode means such as to cause the said a.c. signal applied to said storage material means to produce the said visible change on the said outer display surface, according to said charge storage image pattern.
  • said layer of storage material means comprises a first transparent conductive layer on the said outer display surface thereof and second electroluminescent material layer means in contact with said conductive layer and arranged to provide said secondary emission on the said inner surface thereof in response to said electrons attracted to the charge storage image pattern thereon so as to thereby provide electroluminescence at said selected regions on said display surface in response to said a.c. signal applied to said conductive layer.
  • collector electrode means is in the form of a conductive grid positioned adjacent the said inner surface.
  • said means to apply an a.c. signal includes DC bias means arranged to DC bias said electroluminescent material so as to reduce leakage current therefrom.
  • a method of operating a cathode ray type storage and display tube device having an electron write gun means, electron flood gun means and an insulating layer at the display surface thereof for storing a charge pattern thereon with said write gun means, the improvement comprising: 1

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US00263038A 1972-06-15 1972-06-15 Electroluminescent storage display Expired - Lifetime US3796909A (en)

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3875447A (en) * 1972-12-12 1975-04-01 Ibm High writing speed dark-trace tube with flood beam enhancement
US3968394A (en) * 1974-04-01 1976-07-06 Massachusetts Institute Of Technology Cathode ray tube employing faceplate-deposited cathodochromic material and electron beam erase
US4149108A (en) * 1977-06-17 1979-04-10 International Business Machines Corporation Multistable cathode ray type storage display device
US6979947B2 (en) * 2002-07-09 2005-12-27 Si Diamond Technology, Inc. Nanotriode utilizing carbon nanotubes and fibers
US20080012461A1 (en) * 2004-11-09 2008-01-17 Nano-Proprietary, Inc. Carbon nanotube cold cathode
US11519323B1 (en) 2021-09-17 2022-12-06 Caterpillar Inc. Prechamber sparkplug assembly having sparkplug housing structured for liquid cooling

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3875447A (en) * 1972-12-12 1975-04-01 Ibm High writing speed dark-trace tube with flood beam enhancement
US3968394A (en) * 1974-04-01 1976-07-06 Massachusetts Institute Of Technology Cathode ray tube employing faceplate-deposited cathodochromic material and electron beam erase
US4149108A (en) * 1977-06-17 1979-04-10 International Business Machines Corporation Multistable cathode ray type storage display device
US6979947B2 (en) * 2002-07-09 2005-12-27 Si Diamond Technology, Inc. Nanotriode utilizing carbon nanotubes and fibers
US20080012461A1 (en) * 2004-11-09 2008-01-17 Nano-Proprietary, Inc. Carbon nanotube cold cathode
US11519323B1 (en) 2021-09-17 2022-12-06 Caterpillar Inc. Prechamber sparkplug assembly having sparkplug housing structured for liquid cooling

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FR2189863B1 (enExample) 1976-11-12
GB1412206A (en) 1975-10-29
FR2189863A1 (enExample) 1974-01-25
DE2315794A1 (de) 1974-01-03

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