US3035200A - Electroluminescent display device - Google Patents

Electroluminescent display device Download PDF

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Publication number
US3035200A
US3035200A US855419A US85541959A US3035200A US 3035200 A US3035200 A US 3035200A US 855419 A US855419 A US 855419A US 85541959 A US85541959 A US 85541959A US 3035200 A US3035200 A US 3035200A
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Prior art keywords
sheet
electrodes
pulse
edges
light
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Expired - Lifetime
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US855419A
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English (en)
Inventor
Yando Stephen
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GTE Sylvania Inc
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Sylvania Electric Products Inc
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Priority to US855419A priority Critical patent/US3035200A/en
Priority to BE597075A priority patent/BE597075R/fr
Priority to GB39989/60A priority patent/GB971459A/en
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Publication of US3035200A publication Critical patent/US3035200A/en
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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
    • H05B33/26—Light sources with substantially two-dimensional [2D] radiating surfaces characterised by the composition or arrangement of the conductive material used as an electrode
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N3/00—Scanning details of television systems; Combination thereof with generation of supply voltages
    • H04N3/10—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical
    • H04N3/12—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical by switched stationary formation of lamps, photocells or light relays
    • 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

  • Electroluminescent phosphors when under the influence of an externally applied electric field, will luminesce, the intensity of the emitted light being a function of the strength of this applied field. Consequently, films or layers formed from such phosphors can be used as transducers for transforming electrical energy to light energy.
  • a crossed-grid structure is formed wherein a portion of the layer (defined as a cell) is connected between one horizontal conductor and one vertical conductor.
  • a suitable electric potential difference is applied between any one horizontal-vertical conductor pair, the cell connected between this pair will luminesce.
  • these applied potentials can be switched or commutated in such manner as to successively energize each cell in turn, thus producing an eflect analogous to a scanning action in a cathode ray tube.
  • Another object is to improve electroluminescent display devices by eliminating the necessity of using external switching circuitry.
  • Still another object is to provide an electroluminescent display device which, under the control of two or three separate signals, can product a television type image display.
  • 1 provide a rectangular sheet of piezoelectric material.
  • This sheet is provided with first, second, third and fourth edges, each of the second and fourth edges extending between the first and third edges.
  • First and second electrodes are resmctively secured to opposite surfaces of this sheet adjacent the first edge.
  • Third and fourth electrodes are respectively secured to opposite surfaces of the sheet adjacent the second edge.
  • An electroluminescent layer is placed in intimate engagement with one surface of the sheet and is separated from the appropriate electrodes.
  • All four edges of the sheet are terminated in such manner as to absorb, substantially without reflection, any incident elastic wave supplied thereto from the sheet.
  • a first signal for example, a first voltage pulse
  • This first pulse produces, in the region of the sheet subtended by the first and second electrodes, a mechanical strain proportional to the amplitude of the first pulse.
  • a disturbance in the form of a first elastic wave accompanied by a first electric field propagates from the first edge of the sheet towards the third edge where it is absorbed substantially without reflection.
  • the intensity of the first electric field is proportional to the time rate of change of the strain that produced it; stated diiferently, the intensity of the first field is proportional to the first time derivative of the first pulse.
  • a second signal for example a second voltage pulse
  • a second elastic wave accompanied by a second electric field, which propagates from the second edge of the sheet toward the fourth edge where it is absorbed substantially without reflection.
  • the intensity of the second electric field is proportional to the first time derivative of the second pulse.
  • the first and second waves propagate in mutually perpendicular directions.
  • the first and second waves propagate along the sheet, intersect at a small confined region or point, and then continue to propagate, the point of intersection propagating therealong, to generate a line of intersection.
  • the intensities of the first and second electric field are additive at this point of intersection; the resultant total electrical field intensity at this point produces in the electroluminescent layer a spot of light at a position coinciding with this point of intersection.
  • the amount of light emitted by this spot is determined by the total field intensity and increases monotonically therewith.
  • the first and second edges of the piezoelectric sheet can be regarded as representing the ordinate and abscissa of a rectangular coordinate system having an origin defined by the vertex formed by these edges.
  • the line of light extends outward from the origin at fixed angles with respect to the ordinate and abscissa.
  • the relative timing of these pulses is varied so that the second pulse leads the first pulse, the line of light, while maintaining the same fixed angles with respect to the ordinate and abscissa, extends outward from a point on the ordinate displaced from the origin, the ordinate displacement increasing as the time separation of the pulses increases.
  • the line of light While maintaining the same fixed angles, extends outward from a point on the abscissa displaced from the origin, the abscissa displacement increasing as the time separation of the pulses increases.
  • a plurality of parallel lines of ight can be produced in a manner directly analogous to the production of a raster in a cathode ray tube.
  • a modulation signal for example a video signal
  • a third electric field is produced across the entire electroluminescent layer.
  • the intensity of the third field is additive with the summation of the first and second electric fields at any point of intersection of the first and second waves; as a result, the intensity of the light produced at this point Varies with the modulation signal.
  • all of the lines of light can be modulated as desired and a television type image can be displayed.
  • FIG. 1 is an isometric view of one embodiment of my invention
  • FIG. 2 is a cross-sectional view of another embodiment of my invention.
  • FIG. 3 is a 'plot of elastic wave patterns as established in the devices of FIGS. 1 and 2.
  • a thin rectangular sheet 10 of piezoelectric material in this example, the material is a polarized ceramic strip composed of a sintered lead titanate-lead z-irconate mixture.
  • third and fourth electrode-is 18 and 2 which extend across substantially the entire length of the sheet, are secured to opposite surfaces of the sheet adjacent the top edge thereof.
  • An electroluminescent layer 24 is placed in intimate contact with one surface of sheet 10 and spaced apart from the electrodes 12 and 13.
  • Each edge of the sheet is terminated in such manner as to absorb, substantially without reflection, any incident elastic wave propagating in said sheet. This is accomplished by coating the edges and immediately adjacent portions of strip 10 with a material, such as lead, to provide terminations 30, 3'2, 34 and 36.
  • First and second voltage pulses ar applied between electrodes 12 and 14 and electrodes 13 and 2t respec tively. Each pulse establishes a corresponding electric field within a corresponding portion of the sheet subtended between thecorresponding electrodes.
  • the electric field intensity is proportional to the instantaneous value of the appropriate voltage pulse.
  • each. electric field produces, in the corresponding section, a mechanical strain proportional to the instantaneous field intensity. Hence, this strain is proportional to the instantaneous value of the corresponding pulse.
  • the strain produces a disturbance which is proportional to the time rate of change of the strain and, consequently, is also proportional to the first time derivative of the corresponding pulse. This disturbance propagates along the sheet in the form of oppositely directed elastic waves.
  • the first pulse produces a first elastic wave which travels from the left edge of sheet 10 toward the right edge. This wave extends across the entire width of sheet 10. (The first pulse also produces an oppositely directed Wave which is absorbed almost immediately in termination 30 and has no influence upon the operation of my device.)
  • the second pulse produces a second elastic wave which travels from the upper edge toward the lower edge of the strip. This wave extends across the entire length of sheet 10. (The second pulse also produces an oppositely directed wave which is absorbed in termination 34.)
  • Each of the first and second waves, due to the piezoelectric eifect, is accompanied by an electric field, the intensity of which is proportional to the first time derivative of the appropriate control pulse.
  • the widths of the wave fronts of these waves are substantially identical and can be of the same order as the Width of sheet 10 (which can be, for example, 30 mils).
  • the accompanying electric fields are efficiently coincident in space with the wave fronts.
  • the two propagating waves intersect in a small confined region which can be regarded as a point.
  • the region is a square, the length of each side being about 30-40 mils.
  • the intensities of both electric fields are additive at this point; the resultant field produces in the electroluminescent layer a spot of light at a position corresponding to the point of intersection.
  • the amount of light produced is determined by the summation of the electric field intensities and increases monotonically therewith.
  • Each of the first and second travelling electric fields also tends by itself to produce a moving spot of light in the manner described in more detail in my copending patent application Serial No. 784,212, filed December 31, 1958, now Patent No. 2,917,669.
  • the non-linear voltage-brightness characteristic of electroluminescent phosphors are such that any background lighting produced by each separate field is insignificant as compared to the light produced at the point of intersection.
  • the top and left edges of sheet 10 can be regarded as representing the abscissa and ordinate of a rectangular coordinate system having an origin defined by the vertex 0 of these edges.
  • the line of intersection 48 of the first and second waves (which, as indicated previously, is a line of light) will extend outward from the vertex at fixed angles with respect to the ordinate and abscissa.
  • each elastic wave propagates along the sheet with the same velocity V (which is a constant determined by the characteristics of the particular piezoelectric material used).
  • V which is a constant determined by the characteristics of the particular piezoelectric material used.
  • the line of light When the second pulse leads the first pulse, the line of light will be displaced downward and will extend outward from some point of the ordinate. In particular, when the time of lead is K, then the line will be extremely short and will be positioned at the extreme lower left corner of the sheet. (K is the time required for an elastic wave propogated with the velocity V .to travel from one edge of the electroluminescent layer to the opposite edge of the layer.)
  • the line of light will be displaced upward and will extend outward from some point on the abscissa.
  • the time of lag is K, then the line will again be extremely short and will be positioned at the extreme upper right corner of the sheet.
  • A'pulse time control circuit 40 (FIG. 2) responsive to incoming trigger pulses produces first and second pulse trains.
  • the first pulse train which contains x separate first control pulses (where x is the number of different lines of light to be produced), is applied between electrodes 12 and 14.
  • the first control pulses are generated at a fixed recurrence frequency; i.e. these first pulses are equidistantly spaced in time.
  • the second pulse train which contains x separate second control pulses, is applied between contacts 18 and 20.
  • the relative timing of each Nth pulse in the second train (where N is any integer from 1 to x) with respect to the corresponding Nth pulse in the first train must be smoothly varied from +K to K.
  • the scanning operation is initiated when the first pulse in the first train lags the first pulse in the second train by K and is completed when the xth pulse in the second train lags the xth pulse in the first train by K.
  • a description of circuit 40 for producing these pulse trains, together with appropriate waveforms, will be found in my copending application Serial No. 784,212 filed December 31, 1958.
  • the electroluminescent layer be excited by sharp spike-like pulses. Due to the differentiating action of the sheet 10, the pulses in both trains should have a sawtooth waveform to provide this type of excitation.
  • the recurrence frequency of the first pulse train is preferably not higher than the quantity /2 K where the frequency is expressed in cycles per second and K is expressed in seconds. Should higher frequencies be used, for example, the elastic wave produced by a single pulse applied to one set of electrodes can successively intersect with waves produced by two or more pulses applied to the other set of electrodes.
  • FIG. 1 The lines of light thus produced are unmodulated.
  • the structure of FIG. 1 should be modified as shown in FIG. 2. More particularly, in FIG. 2 the electrodes 14 and 20 are replaced by a single conductive film 100, and another conductive film 102 is applied over the exposed surface of the electroluminescent layer 24.
  • a video type signal for example a pulse train of amplitude modulated pulses, is applied between films 100 and 102.
  • this signal varies, the varying electric field produced in the electroluminescent layer by this signal is added to the summation of the first and second fields produced at any point of wave intersection. Consequently, the light intensities of these points are modulated in accordance with the video signal, and one or all of the lines of light can be modulated as desired.
  • An electroluminescent device comprising a four sided sheet of piezoelectric material having first, second, third and fourth edges, said second and fourth edges extending between said first and third edges; first and second electrodes secured to opposite surfaces of said sheet adjacent said first edge; third and fourth electrodes secured to said opposite surfaces adjacent said second edge of said sheet; and an electroluminescent layer placed in intimate engagement with one of said surfaces and spaced apart from said first and third electrodes, said electroluminescent layer and said first and third electrodes being coplanar.
  • An electroluminescent device comprising a four sided sheet of piezoelectric material having first, second, third and fourth edges, said second and fourth edges extending between said first and third edges; first and second electrodes secured to opposite surfaces of said sheet adjacent said first edge; third and fourth electrodes secured to said opposite surfaces adjacent said second edge of said sheet; an electroluminescent layer placed in intimate engagement with one of said surfaces and spaced apart from said first and third electrodes, said electroluminescent layer and said first and third electrodes being coplanar; and first, second, third and fourth terminations afiixed to corresponding edges of said sheet, said terminations absorbing substantially without reflection any incident elastic wave supplied thereto from said sheet.
  • An electroluminescent device comprising a four sided sheet of piezoelectric material having first, second, third and fourth edges, said second and fourth edges extending between said first and third edges; a conductive film secured to one surface of said sheet; a first electrode applied to the opposite surface of said sheet adjacent said first edge; a second electrode applied to said opposite surface adjacent said second edge; and an electroluminescent layer placed in intimate engagement with said opposite surface and spaced apart from said first and second electrodes, said electroluminescent layer and said first and second electrodes being coplanar.
  • An electroluminescent device comprising a four sided sheet of piezoelectric material having first, second, third and fourth edges, said second and fourth edges extending between said first and third edges; a conductive film secured to one surface of said sheet; a first electrode applied to the opposite surface of said sheet adjacent said first edge; a second electrode applied to said opposite surface adjacent said second edge; an electroluminescent layer placed in intimate engagement with said opposite surface and spaced apart from said first and second electrodes, said electroluminescent layer and said first and second electrodes being coplanar; and a second conductive film secured to the exposed surface of said electroluminescent layer, said second film being light transparent.
  • An electroluminescent device comprising a four sided sheet of piezoelectric material having first, second, third and fourth edges, said second and fourth edges extending between said first and third edges; -a conductive film secured to one surface of said sheet; a first electrode applied to the opposite surface of said sheet adjacent said first edge; a second electrode applied to said opposite surface adjacent said second edge; an electroluminescent layer placed in intimate engagement with said opposite surface and spaced apart from said first and second electrodes, said electroluminescent layer and said first and second electrodes being coplanar; a second conductive film secured to the exposed surface of said electroluminescent layer, said second film being light transparent; means to apply a first signal between said first electrode and said first film; means to apply a second signal between said second electrode and said first film; and means to apply a third signal between said second and first films.
  • An electroluminescent device comprising a four sided sheet of piezoelectric material having first, second, third and fourth edges, said second and fourth edges extending between said first and third edges; first and second electrodes secured to opposite surfaces of said sheet adjacent said first edge; third and fourth electrodes secured to said opposite surfaces adjacent said second edge of said sheet; an electroluminescent layer placed in intimate engagement with one of said surfaces and spaced apart from said first and third electrodes, said electroluminescent layer and said first and third electrodes being coplanar; first, second, third and fourth terminations afiixed to corresponding edges of said sheet, said terminations absorbing substantially without reflection any incident elastic wave supplied thereto from said sheet; means to apply a first signal between said first and second electrodes; and means to apply a second signal between said third and fourth electrodes.
  • each of said first and second signals is constituted by a corresponding pulse train.
  • An electroluminescent device comprising a four sided sheet of piezoelectric material having first, second, third and fourth edges, said second and fourth edges extending between said first and third edges; a conductive film secured to one surface of said sheet; a first electrode applied to the opposite surface of said sheet adjacent said first edge; a second electrode applied to said opposite surface adjacent said second edge; an electroluminescent layer placed in intimate engagement with said opposite surface and spaced apart from said first and second electrodes, said electroluminescent layer and said first and second electrodes being coplanar; a second conductive film secured to the exposed surface of said electroluminescent layer, said second film being light transparent; means to apply a first pulse train between said first electrode and said first film; means to apply a second pulse train between said second electrode and said first film; and means to apply a video type signal between said second and first films.
  • An electroluminescent device comprising a rectangular sheet of piezoelectric material; electrode means secured to one surface of said sheet; a first electrode secured to the opposite surface of said sheet adjacent one side thereof; a second electrode secured to said opposite surface adjacent another side thereof, said first and second electrodes extending in substantially orthogonal directions; and an electroluminescent layer secured to said opposite surface and spaced apart from both of said electrodes.
  • a device comprising a rectangular sheet of piezoelectric material; electrode means secured to one surface of said sheet; a first electrode secured to the opposite surface of said sheet adjacent one side thereof; a second electrode secured to said opposite surface adjacent another side thereof, said first and second electrodes extending in substantially orthogonal directions; means to apply a first electrical signal between said first electrode and said electrode means; means to apply a second electrical sig- 7 ma] between said second electrode and said electrode means; and means positioned adjacent said opposite surface and spaced apart from said electrodes, said means being responsive to the electrical fields established Within said sheet by said signals.

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  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Electroluminescent Light Sources (AREA)
  • Illuminated Signs And Luminous Advertising (AREA)
US855419A 1959-11-25 1959-11-25 Electroluminescent display device Expired - Lifetime US3035200A (en)

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US855419A US3035200A (en) 1959-11-25 1959-11-25 Electroluminescent display device
BE597075A BE597075R (fr) 1959-11-25 1960-11-16 Dispositif électroluminescent
GB39989/60A GB971459A (en) 1959-11-25 1960-11-21 Electroluminescent display device

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Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3121824A (en) * 1960-06-16 1964-02-18 Gen Telephone & Elect Electroluminescent information display system
US3145354A (en) * 1960-04-20 1964-08-18 Bell Telephone Labor Inc Circuit element
US3243648A (en) * 1962-03-28 1966-03-29 Gen Telephone & Elect Piezoelectric energy conversion and electroluminescent display device
US3434008A (en) * 1965-10-27 1969-03-18 Int Standard Electric Corp Solid state scanning system
US3453595A (en) * 1964-06-30 1969-07-01 Ibm Optic to acoustic converter for pattern recognition
US3536830A (en) * 1967-05-15 1970-10-27 Bell Telephone Labor Inc Solid state display and light sensitive devices
US3824586A (en) * 1972-09-07 1974-07-16 Univ Leland Stanford Junior Method of and apparatus for analog to digital conversion utilizing acoustic waves
US4403834A (en) * 1979-07-23 1983-09-13 Kley & Associates Acoustic-wave device
US11181799B2 (en) * 2018-05-17 2021-11-23 E Ink California, Llc Piezo electrophoretic display

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2796584A (en) * 1955-03-21 1957-06-18 Hurvitz Hyman Two dimensional electroluminescent display
US2816236A (en) * 1956-06-19 1957-12-10 Gen Electric Method of and means for detecting stress patterns
US2877376A (en) * 1955-09-06 1959-03-10 Itt Phosphor screen device
US2877371A (en) * 1955-08-16 1959-03-10 Itt Information display device
US2922923A (en) * 1959-03-19 1960-01-26 Sylvania Electric Prod Electroluminescent devices
US2951168A (en) * 1958-11-28 1960-08-30 Sylvania Electric Prod Electroluminescent device

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2796584A (en) * 1955-03-21 1957-06-18 Hurvitz Hyman Two dimensional electroluminescent display
US2877371A (en) * 1955-08-16 1959-03-10 Itt Information display device
US2877376A (en) * 1955-09-06 1959-03-10 Itt Phosphor screen device
US2816236A (en) * 1956-06-19 1957-12-10 Gen Electric Method of and means for detecting stress patterns
US2951168A (en) * 1958-11-28 1960-08-30 Sylvania Electric Prod Electroluminescent device
US2922923A (en) * 1959-03-19 1960-01-26 Sylvania Electric Prod Electroluminescent devices

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3145354A (en) * 1960-04-20 1964-08-18 Bell Telephone Labor Inc Circuit element
US3121824A (en) * 1960-06-16 1964-02-18 Gen Telephone & Elect Electroluminescent information display system
US3243648A (en) * 1962-03-28 1966-03-29 Gen Telephone & Elect Piezoelectric energy conversion and electroluminescent display device
US3453595A (en) * 1964-06-30 1969-07-01 Ibm Optic to acoustic converter for pattern recognition
US3434008A (en) * 1965-10-27 1969-03-18 Int Standard Electric Corp Solid state scanning system
US3536830A (en) * 1967-05-15 1970-10-27 Bell Telephone Labor Inc Solid state display and light sensitive devices
US3824586A (en) * 1972-09-07 1974-07-16 Univ Leland Stanford Junior Method of and apparatus for analog to digital conversion utilizing acoustic waves
US4403834A (en) * 1979-07-23 1983-09-13 Kley & Associates Acoustic-wave 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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GB971459A (en) 1964-09-30
BE597075R (fr) 1961-03-15

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