US3792449A - Ferroelectric ceramic storage display tube - Google Patents

Ferroelectric ceramic storage display tube Download PDF

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Publication number
US3792449A
US3792449A US00267750A US3792449DA US3792449A US 3792449 A US3792449 A US 3792449A US 00267750 A US00267750 A US 00267750A US 3792449D A US3792449D A US 3792449DA US 3792449 A US3792449 A US 3792449A
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layer
ferroelectric ceramic
image
material means
stored
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Expired - Lifetime
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US00267750A
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English (en)
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B Kazan
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International Business Machines Corp
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International Business Machines Corp
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    • 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
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11C—STATIC STORES
    • G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
    • G11C11/21—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements
    • G11C11/23—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using electric elements using electrostatic storage on a common layer, e.g. Forrester-Haeff tubes or William tubes

Definitions

  • ABSTRACT v V p U g i p A ferroelectric ceramic is mounted within a CRT in a l [22] J 1972 I strain-biased state, so that'it is birefringent;- A -re- [21] .A l, M 267,750 7 flective layer is mounted adjacent the ceramic, and a photoconductive layer is' mounted'adjacent the'r'eflecv H tive layer.
  • C 340/1731 178/785 178/75 photoconductive layercombination an image written 340/173 340/173 340/173 CR upon regions of a phosphor'target adjacent the photo- [51] II-lt.
  • Gllc conductive layer y an electron beam results in the [58] Field of Search 178/75 D; 340/1732, flow of local charge through corresponding regions of it the ceramic, thereby changing the polarization y l thereaL
  • the flow of polarization charge acts to modu- [561 References and I late the birefringence in the ceramic, in accordance UNITED STATESIPATENTS with the pattern ofthe image.
  • a iscattering modei arrangement isalsoem- IBM Tech. Dis. Bul.
  • CTR bistablephosphor cathode ray storage display tube
  • a ferroelectric ceramic storage display tube whereby electrical information can be stored and selectively erased, at high speeds.
  • non-stored images can be superimposed on stored images, and an electrical readout signal may readily be produced.
  • the inner surface of the glass faceplate of a CRT is provided with a transparent conductive coating upon which is mounted a ferroelectric ceramic wafer.
  • the surface of the wafer is then coated with a mosaic of reflecting conductive elements, and the mosaic surface of the conductive reflecting elements is, in turn, coated with a photoconductive layer.
  • the photoconductive layer is then coated with a transparent conductive coating, and the latter is, in turn, coated with a thin layer of phosphor;
  • the ceramic wafer is arranged to be strain-biased," so that it is birefringent.
  • a write potential applied across the transparent conductive coatings acts to develop, in the ceramic wafer, a transverse field having an intensity which is modulated by the local resistivity of the photoconductive layer.
  • the phosphor when selected areas of the layer of phosphor are bombarded by an electron beam, in accordance with electrical input signals, the phosphor is locally excited, inducing local conductivity in the adjacharge throughcorresponding areas of the ceramic layer, thereby modulating the birefringence in these areas, in accordance with the pattern written by the electron beam.
  • external plane-polarized light reflected back after passing through the ceramic wafer, exhibits a phase delay pattern of the two perpendicular components of the polarized light wherein the components vary from area to area across the ceramic wafer, resulting in a component of polarization perpendicular to the original polarization 7 direction in accordance with the polarization pattern produced therein, during writing. Since only the latter components are transmitduced in the reflected light which is projected upon a viewing screen, and a pattern of varying brightness corresponding to the stored image is produced.
  • the wafer may be operated in a scattering mode.
  • patterns written upon the photoconductive layer, by the electron beam act to cause local polarization changes in the ceramic wafer, whereby external light reflected by the mosaic of reflecting elements is scattered at local regions, in accordance with the written pattern.
  • This process whereby scattering is produced in a ferroelectric ceramic is described in the paper Scattering Mode Ferroelectric Photoconductor Image Storage and Display devices, by W. D. Smith and C. E. Land, Applied Physics Letters, Vol. 20, No. 4, Feb. 15,1972, pp. 169-171.
  • It is a further object of the present invention to provide a ferroelectric ceramic storage and display device wherein the image to be stored and projected thereby I i I bi'ite r"diSjfrekittfeaiidliavn tages of the invention will be'apparent from the following more particular description of preferred embodiing drawings BRIEF DESCRIPTION 'OF THE DRAWINGS DESCRIPTION OF THE PREFERRED *-'EMBODIMENTS'-
  • a ferroelectric ceramic layer or wafer is arranged to operate within the envelope 1 of a cathode ray type storage'tube in a strainbiased mode.
  • the overall configuration of'th'etube is, in general, analogous to any of the variety of conventional cathode ray type storage and display tube arrangements, heretofore employed in the prior art.
  • the envelope land faceplate 3 maybe made of glass, with the faceplate obviously being transparent.
  • the electron writing gun shown generally at 5, comprises a conventional configuration for producing a focused electron beam which can be scanned across the target structure of the tube.
  • electron source 7 acts to emit electrons through focusing element 9, and the field created by the vertical deflection plates 11 and 13.
  • deflection plates 11 and 13 act to control the vertical position of the electron beam.
  • horizontal deflection plates have not been shown.
  • the omitted pair of horizontal deflection plates act to control the horizontal position of the electron beam.
  • this write surface comprises a layer 27 of phosphor, to be described in more detail, hereinafter.
  • Electron source 7 is connected, as shown, to the negative terminal of an appropriate dc source 15. Typically, source 15 may be 5 kv.
  • the intensity of the electron beam is modulated by the control grid of the electron source, i.e., electron gun, in accordance with an input signal (not shown), thereby creating a luminescent pattern on the phosphor layer in accordance with the time varying magnitude or the like of the signal.
  • the inner surface of glass faceplate 3, is provided with a transparent conductive coating or layer 17. Typically, such a conductive layer would be deposited upon.the faceplate.
  • a transparent conductive coating or layer 17 is mounted upon transparent conductive layer 17, is a layer or wafer 19 of ferroelectric ceramic. It isclear, that the ceramic layer 19 may be ments of theinvention, as illustrated in the accompanya 4 forr'nd s par'atelyfarid then cemented to the transparent conductive lay er l7.
  • the ceramic aye ma .bqflsp te ,di El y ne n ucti e layer 17 by any'of a y ariety of conventional techniques, such as byvapordeposition or sputtering techniques
  • the ceramic lay'e r would be about l'inch in diam eter, and '2 mils thickfl I g
  • both the faceplate and the ceramic wafer are maintained in a mechanicallystressed condition so that the polarization direction of the ceramic tends tobe in the direction along the surface of the ferroelectric ceramic.
  • the wafer may be taken as fabricated from fine-grained lead zirconate-lead titanate ferroelectric ceramic materials.
  • the surface of ceramic layer 19 is coated with a mosaic 21 of conductive reflecting elements, comprising, for example, evaporated aluminum.
  • the reflecting elements are, in turn, coated with a photoconductive layer 23.
  • the photoco'nductive material 1 may typically comprise CdS, produced, for example, by
  • transparent conductive layers 17 and 25 may comprise a thin layer of any of a variety of metals or metal oxides, suchas gold or aluminum metal, or metal oxides such as the oxides of tin or indium. Likewise, these materials may be fabricated by any of a variety of conventional fabricating techniques.
  • a thin layer 27 of phosphor is formed thereon, as shown.
  • the thin layer of phosphor may comprise, for example, ZnO, or ZnS, either in powder form, or produced as a continuous film by evaporation.
  • ceramic layer 19, in the embodiment of FIG. 1 is operated in the strain-biased mode.
  • Strain-biasing ferroelectric ceramics is well known to those skilled in the art. Typical of the techniques for achieving a strain-biased condition, are
  • the ferroelectric ceramic layer 19 may typically be strain-biased to produce a uniform strain condition, by bending the faceplate 3.
  • the faceplate may be flexed either inwardly or outwardly to produce of the optical indicatrix along the strain axes.
  • the magnitude of the resultant birefringence can then be controlled by an electric field applied in the thickness di- -tioned to terminal 33 so that dc potential 35 acts to apply a dc voltage across the photoconductive layer 23 ferroelectric ceramic wafer 19 combination, interposed between transparent conductors 17 and 25.
  • dc source 35 would be of the order of 200 volts.
  • the ceramic is assumed to be uniformly polarized as a result of previous erasure.
  • the tube When no electron beam is present, the tube is in a dark condition and the conductivity of the photoconductor of layer 23 is negligible. Accordingly, no polarization charges flow through the ferroelectric layer interposed between the biased transparent conductive layers 17 and 25.
  • the phosphor layer 27 when selected regions of the phosphor layer 27 are bombarded by the electron beam from the electron gun, in accordance with the electrical input signals applied to the control grid thereof to create the image to be written, the phosphor is locally excited, causing local conductivity in the adjacent photoconductive layer 23.
  • This local conductivity in the photoconductive layer results in a flow of local charge through corresponding regions of the ferroelectric wafer, changing its polarization, thereat.
  • the flow of local polarization charge acts to modulate the birefringence in the ceramic wafer, in accordance with the written image.
  • the field applied across the opposite surfaces of the ferroelectricceramic has an intensity which is modulated by the photoconductive layer 23.
  • the image written on phosphor layer 27 remains stored, as a spatial modulation of the birefringence of the ceramic wafer 19.
  • an optical projection system is employed whereby the mosaic of reflecting elements within the tube, interposed between photoconductive layer 23 and ferroelectric ceramic wafer 19, acts to reflect polarized light, in a polarization pattern corresponding to the stored image.
  • Polarizing prism 45 may comprise any of a variety of conventional polarizing'prism's.
  • Light entering the polarizing prism45 in'this manner is passed through imagin'g lens 47, and enters the ferroelectric ceramic wafer 'l9as acollimated beam "of plane-polarizedlight; This light is then reflected back; after passing through the ferroelectric ceramic wafer, as shown.
  • the phase delay of the two perpendicular components of the polarized light will vary, from area to area, across the ferroelectric ceramic wafer, in accordance with the polarization pattern produced in the ferroelectric wafer during writing. Accordingly, a projected pattern of varying brightness, corresponding to the stored image, will pass through the polarizing prism 45, reaching-projection screen 49. Since viewing does not disturb the polarization' pattern in the ferroelectric ceramic during the viewing process, this process may be continued indefinitely.
  • switch 31 in order to erase, switch 31 is positioned at terminal 39, whereby a negative dc voltage is applied across the photoconductive layer-ferroelectrical wafer combination.
  • dc source 41 is of the order of l00 volts.
  • a relatively high resolution can be obtained from a small tube.
  • a 50p. thick ceramic wafer or layer is capable of a limiting resolution of 50 line pairs/mm.
  • a ceramic plate or wafer 2 cm X 2 cm in area With a ceramic plate or wafer 2 cm X 2 cm in area, a total of 1,000 line pairs/mm is possible in both the X and Y directions.
  • each primary electron will produce 100 photons. if these are all absorbed in the photoconductive layer whose quantum gain is, for example, 100, each photon will allow 100 electrons to flow through the photoconductor. In effect, then, each primary beam electron will cause a flow of IO electrons I through the photoconductive layer and ferroelectric ceramic wafer. With a 10p. amp electron beam, this will result in a current of 0.1 A through the ferroelectric ceramic wafer, where the phosphor is bombarded. This current level will produce the required polarization charge of lOOuC in approximately 1 millisecond, al-
  • this light may also be seen on the projection screen with appropriate 'minor'changes; Specifically, these minor changes involve replacing the mosaic of opaque reflecting elements interposed between the ferroelectric ceramic wafer 19 and photoconductive layer 23, with a slightlyconducting multilayer thin-film dichroic'filter which acts to transmit green light and reflect blue light.
  • this dichroic filter may comprise a mosaic of isolated elements having a relatively high conductivity.
  • the phosphor may be scanned, as'in a conventional CRT, producing dynamic or moving images on the viewing screen in green light, without disturbing the stored image (viewed in blue light).
  • switch 31 is maintained in the viewingposition at terminal 37, thus preventing-any changesin polarization in the ferroelectric ceramic wafer.
  • switch 31 is positioned to the erase condition at terminal 39, after an image has been stored in ferroelectric ceramic wafer 19.
  • Phosphor layer 27 is then scanned with the unmodulated electron beam. This causes the flow of charge through successive areas of the ferroelectric ceramic wafer where writing had previously occurred.
  • An electrical output signal may therebybe obtained, by monitoring the current flow through one of the transparent conductive layers, of the photoconductor-ferroelectric ceramic sandwich.
  • thenya storage display tube is capable of extremely high writing and erasing speeds (e.g., l millisecond per frame). Such a tube cannot only be selectively erased, but can also be used to present moving or transient images in one color, superimposed on stored images of another color. In addition, an electrical output signal can be obtained, corresponding to the stored information.
  • FIG. 2 the configuration of the storage tube shown therein, is essentially the same as that shown in FIG. 1.
  • FIG. 2 like reference characters have been employed to identify elements which are the same as corresponding elements in FIG. 1.
  • Typical ceramics exhibiting the scattering mode may comprise rhombohedral-phase.
  • lead-lanthanum zirconate-titanate (referred to as PL ZT materials) withthe ratio of La, Zr, Ti, about 7:65:35.
  • the grain size of the material should be about 4-5 microns.
  • switch 31 is maintained in the write position at terminal 33 to create a field across the ferroelectric ceramic wafer 19 photoconductive layer 23 combination.
  • diffused reflected light from a given scattering site at 51 is focused by lens 57, positioned in the reflection path, to thereby project a light spot or point on projection screen 49, corresponding to the scattering point.
  • those areas of the ceramic which are in the erased condition, i.e., do not cause scattering allow incident light to return to mirror 55, thus not reaching the screen 49.
  • local regions of the ferroelectric where scattering is produced allow a fraction of this light to pass around mirror 55 and therby reach screen 49, where an image is produced.
  • switch 31 is set to the erase position at terminal 39 whereby a negative potential is applied across the ferroelectric ceramic photoconductor amount of reverse current flow through the ceramic and leaving it in the state of zero remanent polarization.
  • the full beam current could be used for erasing, with switch 31 acting to be closed for a lim ited time so that the reverse charge flow leaves the ceramic in the zero remanent polarization condition. It is evident that a generator producing a negative pulse of controlled width may be'used for this latter purpose.
  • a layer of ferroelectric ceramic means mounted v within said tube adjacent the inner surfaceof the display faceplate thereof ina strainbiased condition so as to be birefringent;
  • a layer of reflective material means mounted adja cent said layer of ferroelectric ceramic means
  • a layer of cathodoluminescent phosphor means mounted adjacent said layer of photoconductive material means so that when said phosphor means is locally excited by the electron beam of said tube in accordance with the said image to be stored therein, corresponding regions of local conductivity are created in said layer of photoconductive material means in accordance with said image so as to thereby modulate the said birefringence in said layer of ferroelectric ceramic means to create a stored birefringence pattern therein corresponding to said image; and means to reflect plane-polarized light through the said birefringence pattern of said layer of ferroelectric ceramic means from said layer of reflective material means to thereby obtain a polarization pattern corresponding to the said image'stored in said layer of ferroelectric ceramic means.
  • said means to apply a voltage across the said combination of said layer of ferroelectric ceramic means and said layer of photoconductive material means includes a pair of transparent conductive layers respectivelymounted adjacent thereto oneach side "t f;
  • a cathode ray-type storage display tube arrangement comprising: a layer of rhombohedral-phase lead-lanthanum-zirconate-titinate ferroelectric ceramic material means mounted within said tube adjacent the inner surface of the display faceplate thereof and respon-' sive to have selectively produced therein local scattering sites for selectively diffusing light in accordance with a selected pattern; a layer of reflective material means mounted adjacent said layer of ferroelectric ceramic material means;
  • a layer of cathodolum'inescent phosphor means mounted adjacent said layer of photoconductive material means so that when said phosphor means is locally excited by the electron beam of said tube in accordance with the said image to be stored therein, corresponding regions of local conductivity are created in said layer of photoconductive material means in accordance with said image so as to 1 thereby effect local polarization in said layer offerroelectric ceramic material means to create a stored pattern of scattering sites therein corresponding to said image to be stored; and means to reflect collimated light through said layer of ferroelectric ceramic material means so that light reflected through said pattern of scattering sites is diffused to form said image.

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  • Engineering & Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Transforming Electric Information Into Light Information (AREA)
  • Devices For Indicating Variable Information By Combining Individual Elements (AREA)
  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
US00267750A 1972-06-30 1972-06-30 Ferroelectric ceramic storage display tube Expired - Lifetime US3792449A (en)

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US (1) US3792449A (fr)
JP (1) JPS5342385B2 (fr)
CA (1) CA978251A (fr)
DE (1) DE2329695A1 (fr)
FR (1) FR2191259B1 (fr)
GB (1) GB1374740A (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3859639A (en) * 1972-08-23 1975-01-07 Philips Corp Optical apparatus for establishing logical relationships and for storing
US3906462A (en) * 1973-05-04 1975-09-16 Itek Corp Optical storage device using piezoelectric read-out
US3978458A (en) * 1973-08-21 1976-08-31 Thomson-Csf Selectively erasable optical memory system utilizing a photo excitable ferroelectric storage plate
US4996667A (en) * 1987-04-29 1991-02-26 Sony Corporation Electron beam addressible recording device utilizing ferroelectric recording material
DE4030252A1 (de) * 1990-09-25 1992-03-26 Alten K Verformbare dichtung des spaltes zwischen dem rand einer gebaeudeoeffnung und dem heck eines an diese herangefahrenen fahrzeuges

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4010322A (en) * 1975-07-28 1977-03-01 Westinghouse Electric Corporation High resolution low bandwidth portable telecommunication system
JPH0158520U (fr) * 1987-10-06 1989-04-12
JP2681304B2 (ja) * 1990-05-16 1997-11-26 日本ビクター株式会社 表示装置
JP3747765B2 (ja) * 2000-10-10 2006-02-22 松下電器産業株式会社 ディスプレイ装置

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3659270A (en) * 1970-01-05 1972-04-25 Bell Telephone Labor Inc Strain-biased fine grain ferroelectric ceramic devices for optical image storage and display systems

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3499157A (en) * 1964-08-18 1970-03-03 Nippon Electric Co Light intensity amplifying device utilizing a semiconductor electron-sensitive variable resistance layer

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3659270A (en) * 1970-01-05 1972-04-25 Bell Telephone Labor Inc Strain-biased fine grain ferroelectric ceramic devices for optical image storage and display systems

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
IBM Tech. Dis. Bul. Vol. 5, No. 3, Aug. 1962 pp. 54 56. *
Photostorage System by R. M. Schaffort. *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3859639A (en) * 1972-08-23 1975-01-07 Philips Corp Optical apparatus for establishing logical relationships and for storing
US3906462A (en) * 1973-05-04 1975-09-16 Itek Corp Optical storage device using piezoelectric read-out
US3978458A (en) * 1973-08-21 1976-08-31 Thomson-Csf Selectively erasable optical memory system utilizing a photo excitable ferroelectric storage plate
US4996667A (en) * 1987-04-29 1991-02-26 Sony Corporation Electron beam addressible recording device utilizing ferroelectric recording material
DE4030252A1 (de) * 1990-09-25 1992-03-26 Alten K Verformbare dichtung des spaltes zwischen dem rand einer gebaeudeoeffnung und dem heck eines an diese herangefahrenen fahrzeuges

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FR2191259A1 (fr) 1974-02-01
FR2191259B1 (fr) 1976-05-28
CA978251A (en) 1975-11-18
JPS5342385B2 (fr) 1978-11-10
DE2329695A1 (de) 1974-01-10
GB1374740A (en) 1974-11-20
JPS4964368A (fr) 1974-06-21

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