US3072821A - Display device - Google Patents

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Publication number
US3072821A
US3072821A US72788A US7278860A US3072821A US 3072821 A US3072821 A US 3072821A US 72788 A US72788 A US 72788A US 7278860 A US7278860 A US 7278860A US 3072821 A US3072821 A US 3072821A
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US
United States
Prior art keywords
sheet
layer
voltage
electroluminescent
electrodes
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 - Lifetime
Application number
US72788A
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English (en)
Inventor
Yando Stephen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Verizon Laboratories Inc
GTE LLC
Original Assignee
General Telephone and Electronics Corp
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by General Telephone and Electronics Corp filed Critical General Telephone and Electronics Corp
Priority to US72788A priority Critical patent/US3072821A/en
Priority to GB41668/61A priority patent/GB1011542A/en
Priority to BE610849A priority patent/BE610849A/fr
Application granted granted Critical
Publication of US3072821A publication Critical patent/US3072821A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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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
    • H05B33/12—Light sources with substantially two-dimensional [2D] radiating surfaces
    • H05B33/22—Light sources with substantially two-dimensional [2D] radiating surfaces characterised by the chemical or physical composition or the arrangement of auxiliary dielectric or reflective layers
    • 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
    • H05B33/12—Light sources with substantially two-dimensional [2D] radiating surfaces
    • 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
    • H05B33/12—Light sources with substantially two-dimensional [2D] radiating surfaces
    • H05B33/20—Light sources with substantially two-dimensional [2D] radiating surfaces characterised by the chemical or physical composition or the arrangement of the material in which the electroluminescent material is embedded

Definitions

  • this device comprises a rectangular electroluminescent phosphor layer aflixed to one surface of a rectangular sheet of piezoelectric material.
  • the piezoelectric sheet is provided 'with iirst and third parallel edges ⁇ and second and lfourth parallel edges, the second and fourth parallel edges being located between and perpendicular to the iirst and third edges.
  • the surface arca of the electroluminescent layer is less than that of the piezoelectric sheet and its sides Iare parallel to the edges of the sheet.
  • a transparent conductive layer is placed over the electroluminescent layer while a common grounded conductive layer is secured to the other side of the piezoelectric sheet.
  • First, second, and third electrodes are secured to the piezoelectric sheet between its rst, second, and third edges respectively and the electroluminescent layer.
  • the rst and third electr-odes are parallel to each other land adjacent to opposite sides of the electroluminescent layer while the second electrode is perpendicular to the iirst and third electrodes. All four edges of the sheet are provided with terminations which absorb, substantially Without reflection, any incident elastic waves.
  • a first voltage pulse applied between the first electrode and the grounded layer produces a mechanical strain in the piezoelectric sheet proportion-al to the amplitude of the rst pulse.
  • a disturbance in the form of a first plane elastic wave accompanied by'a first electric field is propagated from the iirst electrode toward the opposite edge of the sheet where it is absorbed by the termination.
  • the intensity of the electric iield is proportional to the time rate of change of the strain that produced it; i.e. the intensity of the iirst electric field is proportional to the first time derivative of the rst pulse.
  • second and third voltage pulses applied between the second and third electrodes respectively and the grounded layer produce second and third plane elastic waves.
  • Each of these waves is accompanied by an electric iield which is propagated from the corresponding electrode toward the opposite edge of the sheet where it is Sabsorbed.
  • the intensity of the second electric field is' proportional to the first time Iderivative of the second voltage pulse, while the intensity of the third electric iield is proportional to the first time derivative of the third voltage pulse.
  • CCk trode is secured to the piezoelectric sheet between the fourth edge of the ysheet andthe electroluminescent layer.
  • a voltage pulse applied between this electrode and ground produces a fourth elastic Wave accompanied by an electric held-which propagates from the fourth electrode toward the opposite edge of the sheet where it is absorbed.
  • the four waves lare caused to intersect upon the selected point resulting in a bright spot of light in the electroluminescent layer at this point. Since the electric fields are additive, the use of four waves instead of three results in a brighter and more intense image.
  • ythe brightest spot yon the electroluminescent layer is always located at the point where all of the waves simultaneously inte-rsect since it is at this point that the greatest voltage is applied across the layer.
  • secondary light outputs may also be produced in the electrolurn-inescent layer Wherever two of the Waves intersect. This secondary light may create a background illumination which tends Contrast ratio may be deiined as the ratio of the light emitted at a selected point on the electrolurninescent layer t-o the light emitted by the remainder of the electroluminescent layer during the time required for an elastic Wave to traverse the layer.
  • the waves initiated at the three electrodes Will intersect at a selected point.
  • the total voltage across the layer at the selected point is 3 v.
  • the waves intersect along diagonal lines as well, producing voltages equal to 2 v. along thesel lines.
  • spurious faint lines of light will be emitted by the electrolurninescent layer along the diagonalsproduced by the intersection of the rst and second and second and third elastic waves.
  • the ratio of the voltages across the electroluminescent layer at the selected point to the voltage at the other intersection of the elastic waves may be only3 to 2 or 4 to 2, the Acontrast ratio is usually considerably higher. This is because the brightness of the light emitted by the electroluminescent layer is a nonlinear function of the voltage applied across it, the increase in brightness being relatively large for a given increase in voltage.
  • Another object is to provide an electroluminescent display device having a high contrast ratio.
  • Still another object is to provide an electro-luminescent display device in which* ahi'gh contrast ratio is achieved without degradation of the image resolution.
  • Yet Ianother object is to provide an electroluminescent ltoward the opposite ends of the sheet. ⁇ .where all of the elastic waves intersect, the non-linear aoraaai display device which presents a relatively low capacitance load to an applied modulation source.
  • a further object is to provide a new and improved electroluminescent display device characterized by the absence of spurious lines on the surface of the electroluminescent panel.
  • a still further object is to provide a display device which is relatively simple and inexpensive to manufacture.
  • a display device comprising a piezoelectric element, an electrically non-linear element and an electroluminescent layer elec- -trically coupled in series between a pair of spaced conductors.
  • Means are provided for exciting the piezoelectric element thereby generating a voltage across the non-linear element and across the electroluminescent layer.
  • ⁇ non-linear resistance layer is secured to the second surface.
  • a transparent conductive film is placed over the electroluminescent layer and a ground conductor is secured to the other side of the non-linear layer. Pairs of electrodes are fastened to opposite surfaces of the piezoelectric sheet at locations adjacent the electro-luminescent layer.
  • the total voltage across the nonlinear resistance and electroluminescent layers is less than at the point where all of the waves converge.
  • the initial current through the non-linear layer at these secondary locations is very much less than at the point where all of the waves intersect.
  • the voltage across the electroluminescent layer reaches only a small percentage of the total available ⁇ voltage during the time when the two waves sweep through their intersection and the I ight emitted by the electroluminescent layer at the secondary intersections is insignificant.
  • FIG. 1 is a cutaway perspective View of one embodiment of a display device utilizing the invention
  • FIG. 2 is a cross-sectional view of the display device of FIG. l.
  • FIG. 3 is a log-log plot depicting the instantaneous current density-voltage characteristic of a typical nonlinear resistance layer used in the device of FIG. 1.
  • FIGS. l and 2 there 'is shown a ⁇ thin, square, polarized, ceramic piezoelectric sheet ⁇ 10 ⁇ Ycomprising a lead titanate-lead zirconate mixture.
  • the non-linear resistance layer 1'2 may be of the type disclosed in my copending application Serial No. 72,789, filed November 30, 1960, which consists of an essentially non-photo-conductive cadmium sullite powder embedded in an epoxy resin.
  • FIG. 3 is a typical curve showing the current density in the non-linear resistance layer one microsecond after a voltage step is applied across the layer.
  • a rst electrode 19 extending across the entire width of the electroluminescent layer 11 is secured to the piezoelectric sheet adjacent one edge of layer 11 while second, third, and fourth electrodes 20, 21 and 22 are secured to the piezoelectric sheet Y10 adjacent the other edges of layer 1d. While four electrodes have been illustrated, it shall be understood that the non-linear resistance layer of this invention may be used with a piezoelectric sheet having any number of electrodes attached thereto.
  • a grounded conductive layer 13 is attached to the bottom of non-linear resistance layer 12 while grounded electrodes 19a (not shown), 20a, 21a (not shown), and 22a are secured to the bottom of the piezoelectric sheet .10 below corresponding top electrodes 19, 20, 21, and 22.
  • a transparent conductive layer 14 is aixed to the top of the electroluminescent layer 11.
  • Layer 14 may be connected directly to grounded conductive layer 13 or a source of modulating voltage 30 may be coupled across layers .14 and 13 4by means of a switch 31. Satisfactory operation may also be obtained if the external connection between layer y14 and layer 13 is omitted.
  • Each edge of the piezoelectric sheet ⁇ 10 is terminated in such manner as .to absorb, substantially without reilection, any incident elastic wave propagated in the sheet. This is accomplished by coating the edges and immediately adjacent portions of sheet 10 with lead to provide terminations 15, 16, 17 and 18.
  • a voltage pulse between electrode 19 and grounded electrode ⁇ 19a causes a irst elastic Wave to be propagated across the piezoelectric sheet l10 at constant speed toward absorbing termination 17.
  • This wave is accompanied by an electric eld having an intensity proportional to the time rate of change of the pulse applied to electrode 19.
  • a reverse wave also emanates from electrode i19 but is absorbed by termination 15 without aiecting the display.
  • Voltage pulses applied to electrodes 20, 21 and 22 cause second, third, and fourth elastic waves, accompanied by corresponding electric elds, to be propagated at the same speed as the first ywave toward terminations 18, 15, and 16 respectively.
  • a pulse voltage having an amplitude equal to 2 v. is applied across the electroluminescent and non-linear resistance layers in series. These voltages occur along diagonal lines forming the loci of the intersections of the waves from perpendicular pairs of electrodes 19 and 20, 20 and 21, 21 and 22, and 22 and y19. In addition, voltages equal to 2 v. appear across the non-linear and electroluminescent layers along vertical and horizontal lines formed by the intersection of vwaves from opposite electrodes 19, 21 and 20, 22
  • the large charging current produces a rapid increase in the voltage across layer 11 and, as a result, a relatively intense spot of light is emitted by the electroluminescent layer at the intersection of the four elastic waves.
  • the light emitted from the elec-troluminescent layer 11 at the point where the the voltage is 2 v. is insignificant when compared to the intensity of the image at the intersection where the applied voltage equals 4 v.
  • the current density in a typical non-linear resistance layer is approximatelyy twenty ve times as great one microsecond after a voltage step of 200 volts is applied to it as it is one microsecond after a step of 100 volts is applied across the layer.
  • a display device comprising a pair of spaced conductors; a sheet of piezoelectric material; an electroluminescent layer; and a voltage responsive electrically nonlinear resistance layer, said piezoelectric material, electroluminescent layer and non-linear resistance layer interposed between said pair of spaced conductors.
  • a display device comprising a pair of spaced conductors; an electroluminescent layer aixed to one of said pair of spaced conductors; a sheet of piezoelectric mate- 6 rial; and a voltageresponsive non-linear resistance layer located adjacent said sheet of piezoelectric material, said non-linear resistance layer and said sheet of piezoelectric material being interposed between said electroluminescent layer and the other of said pair of spaced conductors.
  • a display device comprising a pair of spaced conductors; an electroluminescent layer aixed to one of said pair of spaced conductors; a sheet of piezoelectric material; a voltage responsive non-linear resistance layer located adjacent said sheet of piezoelectric material, said non-linear resistance layer and said sheet of piezoelectric material being interposed between said electroluminescent layer and the other of said pair of spaced conductors; vand means for producing an electric iield across said sheet of piezoelectric material.
  • a display device comprising a pair of spaced conductors; a sheet of piezoelectric material; an electroluminescent layer; and a voltage responsive non-linear resistance layer, said sheet of piezoelectric material, electroluminescent layer, and non-linear resistance layer being interposed between said pair of spaced conductors; and electrode means adapted to receive an applied voltage afxed to said piezoelectric sheet, an elastic wave accompanied by an electric eld being propagated in said sheet of piezoelectric material upon excitation of said electrode means by said applied voltage.
  • a display device comprising a pair of spaced conductors; an electroluminescent layer aflixed to one of said pair of spaced conductors; a sheet of piezoelectric material; a voltage responsive nonrlinear resistance layer located adjacent said sheet of piezoelectric material, said non-linear resistance layer and said sheet of piezoelectric material being interposed between said electroluminescent layer and the other of said pair of spaced conductors; and
  • a display device comprising a pair of spaced conductors; an electroluminescent layer atlixed to one of said pair of spaced conductors; a sheet of piezoelectric material; a voltage responsive non-linear resistance layer located adjacent said sheet of piezoelectric material, said non-linear resistance layer and said sheet of piezoelectric material being interposed between said electroluminescent layer and the other of said pair of spaced conductors; and at least one pair of electrodes secured to opposite surfaces of said piezoelectric sheet adjacent said electroluminescent layer, an elastic wave accompanied by an electric field being propagated in said sheet of piezoelectric material when a voltage is applied across said pair of electrodes.
  • a display device comprising a sheet of piezoelectric material having lirst and second surfaces; an electroluminescent layer having one side affixed to the first surface v of said sheet; a non-linear resistance layer having one side atiixed to the second surface of said sheet; means for controlling the voltage between the sides of said electroluminescent and non-linear resistance layers remote from the surfaces of said piezoelectric sheet; and a plurality of electrode pairs secured to the surfaces of said sheet, an elastic wave accompanied by an electric field being propagated in said sheet when a voltage is applied across an electrode pair.
  • a display device comprising a sheet of piezoelectric material having first and second surfaces; an electroluminescent layer having one side affixed to the rst sur face of said sheet; a non-linear resistance layer having one side aixed to the second surface of said sheet; the sides of said electroluminescent layer and non-linear resistance layers remote from the surfaces of said piezoelectric sheet being maintained at the same potential; and a plurality of electrode pairs secured to the surfaces of said sheet, an elastic wave accompanied by an electric 7 lield being propagated in said sheet when a voltage is apF plied across an electrode pair.
  • a display device comprising a. rectangular sheet of piezoelectric material having first and second Surfaces; a rectangular electroluminescent layer aftiXed to the first surface of said sheet; a non-linear resistance layer aiiixed to the second surface of said sheet; a transparent conductive layer atiixed to the side of said electroluminescent layer remote from the first surface of said sheet; a conductive layer aiiixed to the side of said non-linear resistance layer remote from the second surface of said sheet; and first and second pairs of electrodes secured to said sheet adjacent said electroluminescent layer, said first and second pairs of electrodes being located along perpendicular edges of said rectangular sheet, elastic Waves accompanied by corresponding electric fields being propagated in said sheet when voltages are applied across said electrode pairs.
  • a display device comprising a rectangular sheet of piezoelectric material having first and second surfaces; a rectangular electroluminescent layer affixed to the first surface of said sheet; a non-linear resistance layer axed to the second surface of said sheet; a transparent conductive layer affixed to the sideI of said electroluminescent layer remote from the first surface of said sheet; a con- 2 ductive layer affixed to the side of said nonalinear resistance layer remote from the second surface of said sheet;
  • each of said pairs of electrodes being located along a corresponding edge of said rectangular piezoelectric sheet, elastic waves accompanied by corresponding electric fields being propagated in said sheet when voltages are applied across each of said electrode pairs.
  • a display device comprising a sheet of piezoelectric material having first and second surfaces;Y an electroluminescent layer affixed to the first surface of said sheet; a non-linear resistance layer afiixed to the second surface of said sheet; means for controlling the voltage between the sides of said electroluminescent and non-linear resistance layers remote from the surfaces of said piezoelectric sheet; a plurality of electrode pairs secured 4to the surfaces of said sheet, an elastic wave accompanied by an electric lield being propagated in said sheet When a voltage is -applied across an electrode pair; and termination means aiiixed to the edge of said sheet, said termination means absorbing substantially without reection any incident elastic wave supplied thereto from said sheet.

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  • Electroluminescent Light Sources (AREA)
  • Illuminated Signs And Luminous Advertising (AREA)
US72788A 1960-11-30 1960-11-30 Display device Expired - Lifetime US3072821A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
US72788A US3072821A (en) 1960-11-30 1960-11-30 Display device
GB41668/61A GB1011542A (en) 1960-11-30 1961-11-21 Display device
BE610849A BE610849A (fr) 1960-11-30 1961-11-28 Dispositif d'affichage de signaux électriques

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Application Number Priority Date Filing Date Title
US72788A US3072821A (en) 1960-11-30 1960-11-30 Display device

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US3072821A true US3072821A (en) 1963-01-08

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BE (1) BE610849A (fr)
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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3202868A (en) * 1962-10-24 1965-08-24 Gen Telephone & Elect Electroluminescent-piezoelectric bar graph display system
US3275871A (en) * 1964-02-17 1966-09-27 Sperry Rand Corp Display apparatus
US3453595A (en) * 1964-06-30 1969-07-01 Ibm Optic to acoustic converter for pattern recognition
US3824586A (en) * 1972-09-07 1974-07-16 Univ Leland Stanford Junior Method of and apparatus for analog to digital conversion utilizing acoustic waves
US4627182A (en) * 1985-06-03 1986-12-09 Tempo Instrument Incorporated Bi-stable display device
US11181799B2 (en) * 2018-05-17 2021-11-23 E Ink California, Llc Piezo electrophoretic display

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2816236A (en) * 1956-06-19 1957-12-10 Gen Electric Method of and means for detecting stress patterns
US2922923A (en) * 1959-03-19 1960-01-26 Sylvania Electric Prod Electroluminescent devices

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2816236A (en) * 1956-06-19 1957-12-10 Gen Electric Method of and means for detecting stress patterns
US2922923A (en) * 1959-03-19 1960-01-26 Sylvania Electric Prod Electroluminescent devices

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3202868A (en) * 1962-10-24 1965-08-24 Gen Telephone & Elect Electroluminescent-piezoelectric bar graph display system
US3275871A (en) * 1964-02-17 1966-09-27 Sperry Rand Corp Display apparatus
US3453595A (en) * 1964-06-30 1969-07-01 Ibm Optic to acoustic converter for pattern recognition
US3824586A (en) * 1972-09-07 1974-07-16 Univ Leland Stanford Junior Method of and apparatus for analog to digital conversion utilizing acoustic waves
US4627182A (en) * 1985-06-03 1986-12-09 Tempo Instrument Incorporated Bi-stable display device
US11181799B2 (en) * 2018-05-17 2021-11-23 E Ink California, Llc Piezo electrophoretic display
US11892740B2 (en) 2018-05-17 2024-02-06 E Ink Corporation Piezo electrophoretic display
US12298645B2 (en) 2018-05-17 2025-05-13 E Ink Corporation Piezo electrophoretic display

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BE610849A (fr) 1962-03-16
GB1011542A (en) 1965-12-01

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