US3749977A - Electroluminescent device - Google Patents
Electroluminescent device Download PDFInfo
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- US3749977A US3749977A US00102354A US3749977DA US3749977A US 3749977 A US3749977 A US 3749977A US 00102354 A US00102354 A US 00102354A US 3749977D A US3749977D A US 3749977DA US 3749977 A US3749977 A US 3749977A
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- 239000000463 material Substances 0.000 claims description 16
- -1 polypropylene Polymers 0.000 claims description 11
- 239000004743 Polypropylene Substances 0.000 claims description 9
- 229920001155 polypropylene Polymers 0.000 claims description 9
- 239000004793 Polystyrene Substances 0.000 claims description 8
- 229920005990 polystyrene resin Polymers 0.000 claims description 8
- 229920005989 resin Polymers 0.000 claims description 8
- 239000011347 resin Substances 0.000 claims description 8
- 239000004593 Epoxy Substances 0.000 claims description 7
- 229920002223 polystyrene Polymers 0.000 claims description 7
- 229920000728 polyester Polymers 0.000 claims description 6
- 229920002492 poly(sulfone) Polymers 0.000 claims description 5
- 229920000647 polyepoxide Polymers 0.000 claims description 2
- 229920001225 polyester resin Polymers 0.000 claims description 2
- 239000004645 polyester resin Substances 0.000 claims description 2
- 239000003989 dielectric material Substances 0.000 description 7
- 239000010408 film Substances 0.000 description 6
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 5
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- 238000010586 diagram Methods 0.000 description 2
- 230000010355 oscillation Effects 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 239000000725 suspension Substances 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 229920006267 polyester film Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
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Images
Classifications
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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 radiating surfaces
- H05B33/20—Light sources with substantially two-dimensional radiating surfaces characterised by the chemical or physical composition or the arrangement of the material in which the electroluminescent material is embedded
-
- 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 radiating surfaces
- H05B33/22—Light sources with substantially two-dimensional 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
- H05B44/00—Circuit arrangements for operating electroluminescent light sources
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10S315/00—Electric lamp and discharge devices: systems
- Y10S315/07—Starting and control circuits for gas discharge lamp using transistors
Definitions
- ABSTRACT An electroluminescent panel or sheeting requiring minimum power for acceptable brightness and including luminescent phosphors imbedded in a dielectric medium between a pair of electrodes connected" to an AC source, the medium being selected to have low electrical loss as determined by the ratio of its dissipation factor to its dielectric constant at the operation frequency of the source.
- the panel is connected with an inductor in a resonant circuit with the frequency of the AC source being adjusted to the resonant frequency of the circuit.
- Electroluminescent devices basically comprise luminescent phosphors suspended in a dielectric medium sandwiched between a pair of electrodes which are connected to a source of alternating current. Electroluminescent devices for use as large area panels or signs, for example, have not enjoyed widespread use for a variety of reasons, a principal one being that in order to achieve an acceptable level of brightness a large amount of power is required. Even if the power cost were not a significant factor, the large amount of power produces excessive heat with consequent rapid degradation of the components of the panels so that their useful life is shortened to such an extent that they are economically unacceptable for commercial use except as low-power, low-light-intensity units for such use as night lights and the like.
- the power requirements for an; electroluminescent panel can be reduced by treating the panel as a capacitor and connecting it with a properly matched inductor in a resonant circuit with the source being adjusted to the resonant frequency of the circuit. This arrangement eliminates the reactive load on the source due to the capacitance of the electroluminescent panel and thus lowers the power requirement.
- the dissipation factor of a medium is of a magnitude such that the ratio of the dissipation factor (D) to the dielectric constant (K) of the medium does not exceed a predetermined low value.
- D/K factor the electrical loss due to the pure resistance of the dielectric medium is also low so that when an electroluminescent panel utilizing such a medium is connected in a resonant circuit operating at resonance, not only is the capacitive reactance of the panel cancelled out but because of the low electrical loss of the medium, the panel requires less power to produce an acceptable level of brightness than has heretofore been achieved by panels of the prior art.
- the object of the invention is to provide an electroluminescent panel or sheeting and driving means therefore which operate at a high level of efficiency to provide acceptable light levels with minimum power requirements and consequent longer life than has been possible heretofore.
- FIG. 1 is an enlarged broken vertical cross sectional view of an electroluminescent panel which may incorporate the features of the invention
- FIG. 2 is a circuit diagram of an oscillator which may be utilized to drive the panel of FIG. 1 connected in a series resonant circuit;
- FIG. 3 is a circuit diagram of a modified oscillator drive means for the panel of FIG. 1;
- FIG. 4 is a graphical representation of the power requirements for operating at various frequencies electroluminescent panels utilizing different selected dielectric media.
- the numeral 10 designates a typical electroluminescent sheeting or panel comprising an integral substrate 12 which may be a flexible film.
- the film is selected to have the electrical loss characteristics on the order of that inherent in polystyrene or polypropylene film.
- a dielectric medium 114 Applied to one side of the film 12 is a dielectric medium 114 having characteristics in accordance with the present invention as will be further described hereinafter.
- luminescent phosphor crystallites 16 Imbedded in the dielectric medium 14 are luminescent phosphor crystallites 16 which preferably have their electrical axes parallel to each other and generally perpendicular to the outer or light emitting surface of the sheeting or panel.
- Electrodes l7, 18, at least one of which is of light transmitting material as, for example, a transparent thin film Connected to the electrode layers 17, 18 are respective conductors 20, 22 leading to a source of alternating current 24 and connected in series between the source 24 and the electrodes is an inductor 26.
- the electroluminescent panel 110 is depicted as comprising a capacitor 28 in series with a resistance 30 which is the normal resistive load or electrical loss of the dielectric medium.
- a second parallel capacitor and resistance 32, 34, representing the capacitive reactance and resistance of the luminescent phosphor materials is shown connected to the resistance 30 and connected in series with the foregoing components is the inductor 26 already mentioned in connection with FIG. I.
- the panel 10 may be operated by an oscillator circuit including three transistors 36, 38 and 41.
- the transistors 36 and 38 form a part of the series output circuit and require phase inversion which is provided by a driver transformer 40 having split secondary windings 4l2, 44.
- the transistor 38 operates as an emitter follower and provides gain of somewhat less than unity while the transistor 36 is connected in common emitter configuration and provides substantial voltage gain.
- the inductor 26 is connected in series with the panel 10 and cancels the reactive part of the load.
- a feed back winding 46 is employed with the inductor 26 to maintain the circuit at resonance at all times and to sustain self-oscillation.
- the oscillator of FIG. 3 is a self-tuned amplifier arranged to provide an exciting voltage between the base and emitter of the transistor 46 that is approximately l out of phase with respect to the alternating voltage developed between the collector and emitter of the transistor.
- the phase relation counteracts the phase reversal produced by the amplifying operation and enables the exciting voltage to have the polarity required to generate the amplifier output.
- the frequency of oscillation is set so that the reactive load due to the capacitance of the panel is cancelled, or if desired the panel can be operated at a predetermined frequency by employing extra capacitance or inductance in series or parallel as the case may be with the load.
- a feedback winding 46 is provided to sustain oscillation.
- f the operating frequency in Hertz
- the electrical loss is proportional to the factor D/K.
- the dielectric constant is not the controlling factor but rather the ratio of the dissipation factor of the medium to its dielectric constant which ratio I have determined should not exceed 0.003 at the operating frequency of the source.
- Dissipation factors and the dielectric constants are known or ascertainable for substantially all dielectric materials and provided the dissipation factor is sufficiently low with respect to the dielectric constant that a maximum D/K value of 0.003 at the operating frequency is not exceeded, any dielectric material may be used so long as it also possesses other necessary characteristics suiting it to use as a component of electroluminescent sheeting. Some of these characteristics are cohesiveness and adhesiveness, low moisture absorption, workability, curability and light transmitting and abo'srbing qualities. Dielectric materials having these qualifications are: polystyrene resins, polytetrafluoroethylene, polypropylene and polysulfones.
- FIG. 4 there is illustrated there the plots of volt ampere power requirements to product 50 foot-Lamberts of brightness at the indicated frequencies for panels of identical dimensions but using different dielectrics.
- the graph designated by the numeral 50 illustrates the power requirements for a panel employing a high dielectric constant material composed of a cyanothylated resin having a D/K ratio of 0.0043 and supporting a copper activated chlorine co-activated, green emitting electroluminescent phosphor.
- the dielectric media and the phosphor particles were mixed and coated to a thickness of 35 microns on a conductive substrate serving as one electrode.
- the panel is 0.1 square meter and after the application of a second electrode the panel had a capacitance of 0.32 microfarads.
- the essentially straight line of the graph 50 was obtained with the panel directly connected to an altemating current source and shows that about 723 volt amps are required to produce a light output of 50 foot- Lamberts at 1,000 Hertz.
- Cyanoethylated resin has a high dielectric constant and the power requirements of 723 volt amps at 1,000 Hertz is substantially less than the power requirements shown by graph 52 for similarly connected and constructed panel employing a low dielectric constant medium composed of polystyrene resin.
- the polystyrene resin requires 3,200 volt amps at 1,000 Hertz to produce the same light intensity as was produced by 723 volt amps for the cyanoethylated resin and this clearly demonstrates why the prior art selected the latter in preference to the former.
- polystyrene resin In addition to a low dielectric constant, polystyrene resin also has a low dissipation factor with a ratio of D/K equal to 0.00013 as compared to 0.0043 for the cyanoethylated material.
- the parameters of the circuit including an inductor of 365 millihenries, being selected to produce resonance at 1,000 Hertz there is, as indicated by the graph 54, a marked and dramatic drop in the power requirements to 42.7 volt amps to produce the same 50 foot-Lamberts of light output as was produced by 3,200 volt amps for the directly connected panel.
- an epoxy resin having a D/K factor equal to 0.0025 was used as a suspension medium for phosphor particles.
- the resin was coated to a dry thickness of 25 microns on a polyester film having a thickness of 12 microns and a D/K factor of 0.0016.
- the panel had an area of 0.1 sq. meter and when electroded on both sides had a capacitance of 0.087 micro farads.
- the panel thus produced had a capacitance of 0.28 microfarads and required 820 volt amps to produce 50 foot-Lamberts of light output at 1,000 Hertz.
- the volt amp requirement for the same light output dropped to 12.7.
- an electroluminescent panel comprising electroluminescent material including a dielectric medium between a pair of spaced electrodes, said dielectric-medium having low electrical loss as determined by a ratio of its dissipation factorto its dielectric constant not in excess of 0.003 and including material selected from the group consisting of polystyrene, polytetrofluroethylene, polypropylene, polysulfone, polyester and epoxy, said panel being connected with an inductor in a resonant circuit, and an alternating current source connected in driving relationship to said prising electroluminescent material including a dielectric medium between a pair of spaced electrodes, said dielectric medium having low electrical loss as determined by a ratio of its dissipation factor to its dielectric constant not in excess of 0.003 and being selected from the group consisting of polystyrene, polytetrofluroethylene, polypropylene, polysulfone, polyester and epoxy, said panel being connected with an inductor in a resonant circuit, and an
- an electroluminescent panel comhaving a D/K ratio not in excess of 0.003 and selected from the group consisting of epoxy, polystyrene, and
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- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Optics & Photonics (AREA)
- Electroluminescent Light Sources (AREA)
- Illuminated Signs And Luminous Advertising (AREA)
Abstract
An electroluminescent panel or sheeting requiring minimum power for acceptable brightness and including luminescent phosphors imbedded in a dielectric medium between a pair of electrodes connected to an AC source, the medium being selected to have low electrical loss as determined by the ratio of its dissipation factor to its dielectric constant at the operation frequency of the source. The panel is connected with an inductor in a resonant circuit with the frequency of the AC source being adjusted to the resonant frequency of the circuit.
Description
[111 3,749,977 [451 July 31,1973
1 1 ELECTROLUMINESCENT DEVICE [75] Inventor: Lawrence S. Sliker, Welland, Fort Erie, Canada [73] Assignee: International Scanning Devices, Inc.,
Fort Erie, Canada [22] Filed: Dec. 29, 1970 [21] Appl. No.: 102,354
[52] -U.S. Cl. 315/276, 313/108 A, 315/169 TV',
315/283 [51] Int. Cl H01j l/64, 1-105b 43/02 [58] Field of Search 315/276, 169, 169 TV, 315/258, 283; 313/108; 324/78 0 [56] References Cited UNITED STATES PATENTS 3,306,770 2/1967 Klug et al. 313/108 A 3,037,137 5/1962 Motson.. 313/108 A 2,810,883 10/1957 Camine 324/78 Q 3,235,799 2/1966 Hurvitz 315/169 TV 2,624,857 1/1953 Mager 313/108 A 3,281,619 10/1966 Greene.. 315/169 TV 3,247,390 4/1966 Kazam. 315/169 TV 2,796,584 6/1957 Hurvitz 324/78 Q X 2,886,777 5/1959 Hurvitz 324/78 Q 3,161,797 12/1964 Butler et a1. 315/169 R X OTHER PUBLICATIONS Von l-lippel, Dielectric Materials and Applications MIT Press, Cambridge, Mass. 1961 QC 585 V6, page 332.
Von Hippel, Dieletric Materials and Applications, MIT Press, Cambridge Cambridge, Mass. 1961, QC .585 V6, Title Page & pp. 327-328, 335-336, 348-350.
Primary Examiner-Rudolph V. Rolinec Assistant Examiner-Marvin Nussbaum Attorney-Scrivener, Parker, Scrivener & Clarke [57] ABSTRACT An electroluminescent panel or sheeting requiring minimum power for acceptable brightness and including luminescent phosphors imbedded in a dielectric medium between a pair of electrodes connected" to an AC source, the medium being selected to have low electrical loss as determined by the ratio of its dissipation factor to its dielectric constant at the operation frequency of the source. The panel is connected with an inductor in a resonant circuit with the frequency of the AC source being adjusted to the resonant frequency of the circuit.
3 Claims, 4 Drawing Figures PAIENIEDJULQ 1 ms SHEEI 1 0f 2 IIIIIIIIIII llllllllllllllll INVENTOR LAWRENCE S. SLIKER ATTORNEYS PATENTED 19H 3'. 749,977 SHEEI 2 0F 2 o O O O o 8 O O o o rm m INVENTOR LAWRENCE S..SL| KER BY mmwmmdauhmvm ATTORNEYS ELECTROLUMINIESCENT DEVICE This invention relates to electroluminescent devices.
Electroluminescent devices basically comprise luminescent phosphors suspended in a dielectric medium sandwiched between a pair of electrodes which are connected to a source of alternating current. Electroluminescent devices for use as large area panels or signs, for example, have not enjoyed widespread use for a variety of reasons, a principal one being that in order to achieve an acceptable level of brightness a large amount of power is required. Even if the power cost were not a significant factor, the large amount of power produces excessive heat with consequent rapid degradation of the components of the panels so that their useful life is shortened to such an extent that they are economically unacceptable for commercial use except as low-power, low-light-intensity units for such use as night lights and the like.
The power requirements for an; electroluminescent panel can be reduced by treating the panel as a capacitor and connecting it with a properly matched inductor in a resonant circuit with the source being adjusted to the resonant frequency of the circuit. This arrangement eliminates the reactive load on the source due to the capacitance of the electroluminescent panel and thus lowers the power requirement.
The use of an electroluminescent panel as part of a resonant circuit has been resorted to by the prior art but heretofore the art has not realized that unexpectedly superior results can be achieved through a careful selection of the dielectric medium supportingthe luminescent phosphors in the electroluminescent panel. For example, the prior art has relied on dielectric suspension media having high dielectric constants such as cyanoethylated resins apparently because such substances require less power than low dielectric constant materials when the panel is directly connected to an AC source in a conventional circuit. Materials having low dielectric constants have been generally shunned because of the relatively much higher power requirement when used in a conventional circuit.
l have discovered that previously discarded dielectric media which may have low dielectric constants produce results superior to the media usually employed heretofore provided also that the dissipation factor of a medium is of a magnitude such that the ratio of the dissipation factor (D) to the dielectric constant (K) of the medium does not exceed a predetermined low value. When the D/K factor is low, the electrical loss due to the pure resistance of the dielectric medium is also low so that when an electroluminescent panel utilizing such a medium is connected in a resonant circuit operating at resonance, not only is the capacitive reactance of the panel cancelled out but because of the low electrical loss of the medium, the panel requires less power to produce an acceptable level of brightness than has heretofore been achieved by panels of the prior art.
Thus the object of the invention is to provide an electroluminescent panel or sheeting and driving means therefore which operate at a high level of efficiency to provide acceptable light levels with minimum power requirements and consequent longer life than has been possible heretofore.
Referring now to the drawings wherein:
FIG. 1 is an enlarged broken vertical cross sectional view of an electroluminescent panel which may incorporate the features of the invention;
FIG. 2 is a circuit diagram of an oscillator which may be utilized to drive the panel of FIG. 1 connected in a series resonant circuit;
FIG. 3 is a circuit diagram of a modified oscillator drive means for the panel of FIG. 1; and
FIG. 4 is a graphical representation of the power requirements for operating at various frequencies electroluminescent panels utilizing different selected dielectric media.
Referring now to the drawings and particularly to FIG. l, the numeral 10 designates a typical electroluminescent sheeting or panel comprising an integral substrate 12 which may be a flexible film. For purposes of the invention, the film is selected to have the electrical loss characteristics on the order of that inherent in polystyrene or polypropylene film. Applied to one side of the film 12 is a dielectric medium 114 having characteristics in accordance with the present invention as will be further described hereinafter. Imbedded in the dielectric medium 14 are luminescent phosphor crystallites 16 which preferably have their electrical axes parallel to each other and generally perpendicular to the outer or light emitting surface of the sheeting or panel. Applied to the upper surface of the dielectric material and to the lower surface of the substrate 12 are respective electrodes l7, 18, at least one of which is of light transmitting material as, for example, a transparent thin film. Connected to the electrode layers 17, 18 are respective conductors 20, 22 leading to a source of alternating current 24 and connected in series between the source 24 and the electrodes is an inductor 26.
Referring now to FIG. 2, the electroluminescent panel 110 is depicted as comprising a capacitor 28 in series with a resistance 30 which is the normal resistive load or electrical loss of the dielectric medium. A second parallel capacitor and resistance 32, 34, representing the capacitive reactance and resistance of the luminescent phosphor materials is shown connected to the resistance 30 and connected in series with the foregoing components is the inductor 26 already mentioned in connection with FIG. I.
The panel 10 may be operated by an oscillator circuit including three transistors 36, 38 and 41. The transistors 36 and 38 form a part of the series output circuit and require phase inversion which is provided by a driver transformer 40 having split secondary windings 4l2, 44. The transistor 38 operates as an emitter follower and provides gain of somewhat less than unity while the transistor 36 is connected in common emitter configuration and provides substantial voltage gain. In the load part of the circuit, the inductor 26 is connected in series with the panel 10 and cancels the reactive part of the load. A feed back winding 46 is employed with the inductor 26 to maintain the circuit at resonance at all times and to sustain self-oscillation.
In lieu of the series arrangement of FIG. 2 a parallel arrangement as shown in FIG. 3 may be employed. The oscillator of FIG. 3 is a self-tuned amplifier arranged to provide an exciting voltage between the base and emitter of the transistor 46 that is approximately l out of phase with respect to the alternating voltage developed between the collector and emitter of the transistor. The phase relation counteracts the phase reversal produced by the amplifying operation and enables the exciting voltage to have the polarity required to generate the amplifier output. The frequency of oscillation is set so that the reactive load due to the capacitance of the panel is cancelled, or if desired the panel can be operated at a predetermined frequency by employing extra capacitance or inductance in series or parallel as the case may be with the load. As with FIG. 2, a feedback winding 46 is provided to sustain oscillation.
Using known functions, it can be shown that the electrical loss in a dielectric material is R, 9 Dd/S flcA X 10" ohms, where:
D dissipation factor of the dielectric media;
d thickness of the dielectric media in meters;
f= the operating frequency in Hertz;
K dielectric constant of the media;
A useful area in square meters.
Where the physical dimensions of the panel and the frequency of the electric drive means are constant, the electrical loss is proportional to the factor D/K. ln accordance with the invention, with the D/K factor of the dielectric medium as small as possible when an electroluminescent panel employing such a medium is connected in a resonant circuit operating at resonance, surprisingly low power is required to operate the panel at an acceptable degree of brightness despite the fact that the dielectric medium may have a lower dielectric constant than had heretofore been considered feasible. in accordance with the invention, the dielectric constant is not the controlling factor but rather the ratio of the dissipation factor of the medium to its dielectric constant which ratio I have determined should not exceed 0.003 at the operating frequency of the source.
Dissipation factors and the dielectric constants are known or ascertainable for substantially all dielectric materials and provided the dissipation factor is sufficiently low with respect to the dielectric constant that a maximum D/K value of 0.003 at the operating frequency is not exceeded, any dielectric material may be used so long as it also possesses other necessary characteristics suiting it to use as a component of electroluminescent sheeting. Some of these characteristics are cohesiveness and adhesiveness, low moisture absorption, workability, curability and light transmitting and abo'srbing qualities. Dielectric materials having these qualifications are: polystyrene resins, polytetrafluoroethylene, polypropylene and polysulfones.
Referring now to FIG. 4, there is illustrated there the plots of volt ampere power requirements to product 50 foot-Lamberts of brightness at the indicated frequencies for panels of identical dimensions but using different dielectrics. The graph designated by the numeral 50 illustrates the power requirements for a panel employing a high dielectric constant material composed of a cyanothylated resin having a D/K ratio of 0.0043 and supporting a copper activated chlorine co-activated, green emitting electroluminescent phosphor. The dielectric media and the phosphor particles were mixed and coated to a thickness of 35 microns on a conductive substrate serving as one electrode. The panel is 0.1 square meter and after the application of a second electrode the panel had a capacitance of 0.32 microfarads. The essentially straight line of the graph 50 was obtained with the panel directly connected to an altemating current source and shows that about 723 volt amps are required to produce a light output of 50 foot- Lamberts at 1,000 Hertz. Cyanoethylated resin has a high dielectric constant and the power requirements of 723 volt amps at 1,000 Hertz is substantially less than the power requirements shown by graph 52 for similarly connected and constructed panel employing a low dielectric constant medium composed of polystyrene resin. As can be seen, the polystyrene resin requires 3,200 volt amps at 1,000 Hertz to produce the same light intensity as was produced by 723 volt amps for the cyanoethylated resin and this clearly demonstrates why the prior art selected the latter in preference to the former.
In addition to a low dielectric constant, polystyrene resin also has a low dissipation factor with a ratio of D/K equal to 0.00013 as compared to 0.0043 for the cyanoethylated material. Thus when the same panel employing polystyrene resin as the dielectric medium was placed in a resonant circuit with the parameters of the circuit, including an inductor of 365 millihenries, being selected to produce resonance at 1,000 Hertz there is, as indicated by the graph 54, a marked and dramatic drop in the power requirements to 42.7 volt amps to produce the same 50 foot-Lamberts of light output as was produced by 3,200 volt amps for the directly connected panel.
Though connecting a panel using cyanoethylated material in a resonant circuit would also lower the power requirements, experiments have shown that this would at best lower the power to between and volt amps which is not as great an improvement as achieved by the polystyrene resin with its significantly lower D/K factor.
In another experiment, an epoxy resin having a D/K factor equal to 0.0025 was used as a suspension medium for phosphor particles. The resin was coated to a dry thickness of 25 microns on a polyester film having a thickness of 12 microns and a D/K factor of 0.0016. The panel had an area of 0.1 sq. meter and when electroded on both sides had a capacitance of 0.087 micro farads. It was found that in a direct connection with an AC source, 2,650 volt amps were required at 1,000 Hertz to produce a light output of 50 foot-Lamberts whereas when the same panel was connected in a resonant circuit with an inductance equal to 292 millihenries, 58.7 volt amps were required to produce the same foot-Lamberts of light intensity.
When materials were used having better D/K factors than those used in the example immediately above, the results were markedly improved. For example, a polystyrene resin having a D/K factor equal to 0.00013 was used in place of the epoxy on a polypropylene film having a D/K factor equal to 0.00014. All dimensions and other materials were the same and when this panel was electroded it had a capacitance equal to 0.06 microfarads. When used in a direct circuit 3,830 volt amps were required to produce a light output of 50 foot-Lamberts but when an inductor equal to 420 millihenries was added to the circuit only 43.8 volt amps were required to produce the same light output.
As a final example illustrating again the significance of the low D/K factor, when a 2-micron-thick electroluminescent layer was evaporated directly on a 6-micronthick polypropylene film having an area of 0.1 sq. meter, the panel thus produced had a capacitance of 0.28 microfarads and required 820 volt amps to produce 50 foot-Lamberts of light output at 1,000 Hertz. When a millihenry inductor was added to the circuit, the volt amp requirement for the same light output dropped to 12.7.
Though one specific electroluminescent panel has been shown and described, it should be understood that the invention is not limited to this type of panel but may be used with the same results with panels or sheeting of other configurations. What is claimed is:
1. In combination, an electroluminescent panel comprising electroluminescent material including a dielectric medium between a pair of spaced electrodes, said dielectric-medium having low electrical loss as determined by a ratio of its dissipation factorto its dielectric constant not in excess of 0.003 and including material selected from the group consisting of polystyrene, polytetrofluroethylene, polypropylene, polysulfone, polyester and epoxy, said panel being connected with an inductor in a resonant circuit, and an alternating current source connected in driving relationship to said prising electroluminescent material including a dielectric medium between a pair of spaced electrodes, said dielectric medium having low electrical loss as determined by a ratio of its dissipation factor to its dielectric constant not in excess of 0.003 and being selected from the group consisting of polystyrene, polytetrofluroethylene, polypropylene, polysulfone, polyester and epoxy, said panel being connected with an inductor in a resonant circuit, and an alternating current source connected in driving relationship to said resonant circuit polytetrofiuroethylene, and polyester and said resin resonant circuit and operating atthe resonant frequency of said circuit.
2. In combination, an electroluminescent panel comhaving a D/K ratio not in excess of 0.003 and selected from the group consisting of epoxy, polystyrene, and
polyester resin.
* I I 1 t
Claims (3)
1. In combination, an electroluminescent panel comprising electroluminescent material including a dielectric medium between a pair of spaced electrodes, said dielectric medium having low electrical loss as determined by a ratio of its dissipation factor to its dielectric constant not in excess of 0.003 and including material selected from the group consisting of polystyrene, polytetrofluroethylene, polypropylene, polysulfone, polyester and epoxy, said panel being connected with an inductor in a resonant circuit, and an alternating current source connected in driving relationship to said resonant circuit and operating at the resonant frequency of said circuit.
2. In combination, an electroluminescent panel comprising electroluminescent material including a dielectric medium between a pair of spaced electrodes, said dielectric medium having low electrical loss as determined by a ratio of its dissipation factor to its dielectric constant not in excess of 0.003 and being selected from the group consisting of polystyrene, polytetrofluroethylene, polypropylene, polysulfone, polyester and epoxy, said panel being connected with an inductor in a resonant circuit, and an alternating current source connected in driving relationship to said resonant circuit and operating at the resonant frequency of said circuit.
3. The electroluminescent sheeting of claim 2 wherein said dielectric medium comprises flexible film and a resin applied to said film, said film having a D/K ratio not in excess of 0.0016 and selected from the group consisting of polystyrene, polypropylene, polytetrofluroethylene, and polyester and said resin having a D/K ratio not in excess of 0.003 and selected from the group consisting of epoxy, polystyrene, and polyester resin.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US10235470A | 1970-12-29 | 1970-12-29 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3749977A true US3749977A (en) | 1973-07-31 |
Family
ID=22289411
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US00102354A Expired - Lifetime US3749977A (en) | 1970-12-29 | 1970-12-29 | Electroluminescent device |
Country Status (11)
Country | Link |
---|---|
US (1) | US3749977A (en) |
JP (1) | JPS4862387A (en) |
BE (1) | BE777481A (en) |
BR (1) | BR7108645D0 (en) |
CA (1) | CA947372A (en) |
DE (1) | DE2165424C3 (en) |
FR (1) | FR2120927A5 (en) |
GB (1) | GB1382256A (en) |
IT (1) | IT951617B (en) |
NL (1) | NL7117935A (en) |
SE (1) | SE7116687L (en) |
Cited By (27)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4253097A (en) * | 1979-03-29 | 1981-02-24 | Timex Corporation | Method and apparatus for reducing power consumption to activate electroluminescent panels |
US4254362A (en) * | 1979-07-30 | 1981-03-03 | Midland-Ross Corporation | Power factor compensating electroluminescent lamp DC/AC inverter |
US4266223A (en) * | 1978-12-08 | 1981-05-05 | W. H. Brady Co. | Thin panel display |
US4319164A (en) * | 1979-07-30 | 1982-03-09 | Midland-Ross Corporation | Power factor compensating electroluminescent lamp DC/AC inverter |
WO1986001364A1 (en) * | 1984-08-16 | 1986-02-27 | Ball Engineering Corp. | Load responsive inverter for electroluminescent lamp |
WO1986005304A1 (en) * | 1985-02-28 | 1986-09-12 | Motorola, Inc. | A low voltage power source power inverter for an electroluminescent device |
US4707692A (en) * | 1984-11-30 | 1987-11-17 | Hewlett-Packard Company | Electroluminescent display drive system |
US4733228A (en) * | 1985-07-31 | 1988-03-22 | Planar Systems, Inc. | Transformer-coupled drive network for a TFEL panel |
US4775964A (en) * | 1988-01-11 | 1988-10-04 | Timex Corporation | Electroluminescent dial for an analog watch and process for making it |
US4877988A (en) * | 1982-03-01 | 1989-10-31 | Battelle Memorial Institute | Piezoelectric and pyroelectric polymers |
US4882517A (en) * | 1988-02-09 | 1989-11-21 | Shin-Etsu Chemical Co., Ltd. | Electroluminescent composition containing organopolysiloxane and electroluminescent device usable as a back-lighting unit for liquid crystal display |
US5027040A (en) * | 1988-09-14 | 1991-06-25 | Daichi Company, Ltd. | EL operating power supply circuit |
US5532553A (en) * | 1994-10-19 | 1996-07-02 | Hubbell Incorporated | Operating circuit for electroluminescent panel |
DE29512835U1 (en) * | 1995-08-09 | 1996-12-05 | GEZ Gesellschaft für elektrische Zugausrüstung mbH, 60388 Frankfurt | Lighting device |
US5764599A (en) * | 1996-08-12 | 1998-06-09 | Timex Corporation | Electroluminescent lamp and dial for a timepiece |
US5838113A (en) * | 1995-02-28 | 1998-11-17 | Sgs-Thomson Microelectronics K.K. | Power supply circuit employing a differential amplifier connected to an AND gate that is in turn connected to flip-flop |
US5963443A (en) * | 1995-12-14 | 1999-10-05 | Stmicroelectronics K.K. | Power circuit for driving a capacitive load |
WO2000057425A1 (en) | 1999-03-19 | 2000-09-28 | Luminary Logic Limited | Illuminating device for watches, gauges and similar devices |
US6486561B1 (en) | 2000-09-12 | 2002-11-26 | Luminary Logic, Ltd. | Semiconductor light emitting element formed on a clear or translucent substrate |
US6729738B2 (en) | 2001-05-03 | 2004-05-04 | Luminary Logic Ltd. | Illumination devices for watches and other instruments |
EP1425773A1 (en) * | 2001-09-11 | 2004-06-09 | Frito-Lay North America, Inc. | Electroluminescent flexible film for product packaging |
US20040212988A1 (en) * | 2003-04-28 | 2004-10-28 | Fuwausa Michelle Jillian | Illumination devices using LEDs |
US6819308B2 (en) | 2001-12-26 | 2004-11-16 | Ifire Technology, Inc. | Energy efficient grey scale driver for electroluminescent displays |
US20050104531A1 (en) * | 2003-10-20 | 2005-05-19 | Park Joong S. | Apparatus for energy recovery of a plasma display panel |
US20050253530A1 (en) * | 2004-05-11 | 2005-11-17 | Harold Feldman | Electroluminescent device |
US20060290289A1 (en) * | 2004-05-11 | 2006-12-28 | Harold Feldman | Electroluminescent device including a programmable pattern generator |
US20140152621A1 (en) * | 2011-11-11 | 2014-06-05 | Panasonic Corporation | Touch-panel device |
Families Citing this family (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4149108A (en) * | 1977-06-17 | 1979-04-10 | International Business Machines Corporation | Multistable cathode ray type storage display device |
EP0131635A1 (en) * | 1983-07-06 | 1985-01-23 | Timex Corporation | Electroluminescent lighting system having a phosphor/epoxy mixture for a high frequency electroluminescent lamp |
BR8507087A (en) * | 1984-12-03 | 1987-03-31 | Luminescent Electronics Inc | ELECTROLUMINESCENT PANELS |
GB2196805B (en) * | 1986-10-30 | 1990-06-20 | Timex Corp | Low voltage electroluminescent lamp driver circuits |
JPS63202888A (en) * | 1987-02-13 | 1988-08-22 | インターナシヨナル・ビジネス・マシーンズ・コーポレーシヨン | Electric source circuit for el panel |
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- 1970-12-29 US US00102354A patent/US3749977A/en not_active Expired - Lifetime
-
1971
- 1971-12-23 CA CA131,016A patent/CA947372A/en not_active Expired
- 1971-12-27 SE SE7116687A patent/SE7116687L/sv unknown
- 1971-12-27 FR FR7146824A patent/FR2120927A5/fr not_active Expired
- 1971-12-28 NL NL7117935A patent/NL7117935A/xx unknown
- 1971-12-29 JP JP47004151A patent/JPS4862387A/ja active Pending
- 1971-12-29 BE BE777481A patent/BE777481A/en unknown
- 1971-12-29 GB GB6049771A patent/GB1382256A/en not_active Expired
- 1971-12-29 BR BR8645/71A patent/BR7108645D0/en unknown
- 1971-12-29 DE DE2165424A patent/DE2165424C3/en not_active Expired
- 1971-12-29 IT IT33086/71A patent/IT951617B/en active
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US3281619A (en) * | 1963-03-27 | 1966-10-25 | Gen Electric | Electroluminescent display device with edge terminated contacts overlying an apertured low dielectric insulator sheet |
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Cited By (38)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4266223A (en) * | 1978-12-08 | 1981-05-05 | W. H. Brady Co. | Thin panel display |
US4253097A (en) * | 1979-03-29 | 1981-02-24 | Timex Corporation | Method and apparatus for reducing power consumption to activate electroluminescent panels |
US4254362A (en) * | 1979-07-30 | 1981-03-03 | Midland-Ross Corporation | Power factor compensating electroluminescent lamp DC/AC inverter |
US4319164A (en) * | 1979-07-30 | 1982-03-09 | Midland-Ross Corporation | Power factor compensating electroluminescent lamp DC/AC inverter |
US4877988A (en) * | 1982-03-01 | 1989-10-31 | Battelle Memorial Institute | Piezoelectric and pyroelectric polymers |
WO1986001364A1 (en) * | 1984-08-16 | 1986-02-27 | Ball Engineering Corp. | Load responsive inverter for electroluminescent lamp |
US4611150A (en) * | 1984-08-16 | 1986-09-09 | Microlite, Inc. | Load responsive inverter for electroluminescent lamp |
US4707692A (en) * | 1984-11-30 | 1987-11-17 | Hewlett-Packard Company | Electroluminescent display drive system |
WO1986005304A1 (en) * | 1985-02-28 | 1986-09-12 | Motorola, Inc. | A low voltage power source power inverter for an electroluminescent device |
US4633141A (en) * | 1985-02-28 | 1986-12-30 | Motorola, Inc. | Low voltage power source power inverter for an electroluminescent drive |
US4733228A (en) * | 1985-07-31 | 1988-03-22 | Planar Systems, Inc. | Transformer-coupled drive network for a TFEL panel |
US4775964A (en) * | 1988-01-11 | 1988-10-04 | Timex Corporation | Electroluminescent dial for an analog watch and process for making it |
FR2625817A1 (en) * | 1988-01-11 | 1989-07-13 | Timex Corp | ELECTROLUMINESCENT DIAL FOR ANALOG WATCH |
US4882517A (en) * | 1988-02-09 | 1989-11-21 | Shin-Etsu Chemical Co., Ltd. | Electroluminescent composition containing organopolysiloxane and electroluminescent device usable as a back-lighting unit for liquid crystal display |
US5027040A (en) * | 1988-09-14 | 1991-06-25 | Daichi Company, Ltd. | EL operating power supply circuit |
AU631375B2 (en) * | 1988-09-14 | 1992-11-26 | Daichi Co., Ltd. | El operating power supply circuit |
US5532553A (en) * | 1994-10-19 | 1996-07-02 | Hubbell Incorporated | Operating circuit for electroluminescent panel |
US5838113A (en) * | 1995-02-28 | 1998-11-17 | Sgs-Thomson Microelectronics K.K. | Power supply circuit employing a differential amplifier connected to an AND gate that is in turn connected to flip-flop |
DE29512835U1 (en) * | 1995-08-09 | 1996-12-05 | GEZ Gesellschaft für elektrische Zugausrüstung mbH, 60388 Frankfurt | Lighting device |
US5963443A (en) * | 1995-12-14 | 1999-10-05 | Stmicroelectronics K.K. | Power circuit for driving a capacitive load |
US5764599A (en) * | 1996-08-12 | 1998-06-09 | Timex Corporation | Electroluminescent lamp and dial for a timepiece |
WO2000057425A1 (en) | 1999-03-19 | 2000-09-28 | Luminary Logic Limited | Illuminating device for watches, gauges and similar devices |
US6486561B1 (en) | 2000-09-12 | 2002-11-26 | Luminary Logic, Ltd. | Semiconductor light emitting element formed on a clear or translucent substrate |
US6729738B2 (en) | 2001-05-03 | 2004-05-04 | Luminary Logic Ltd. | Illumination devices for watches and other instruments |
US20040085752A1 (en) * | 2001-05-03 | 2004-05-06 | Fuwausa Michelle Jillian | Illumination devices for watches and other instruments |
EP1425773A1 (en) * | 2001-09-11 | 2004-06-09 | Frito-Lay North America, Inc. | Electroluminescent flexible film for product packaging |
EP1425773A4 (en) * | 2001-09-11 | 2009-09-02 | Frito Lay North America Inc | Electroluminescent flexible film for product packaging |
US6819308B2 (en) | 2001-12-26 | 2004-11-16 | Ifire Technology, Inc. | Energy efficient grey scale driver for electroluminescent displays |
US20040212988A1 (en) * | 2003-04-28 | 2004-10-28 | Fuwausa Michelle Jillian | Illumination devices using LEDs |
US7355350B2 (en) | 2003-10-20 | 2008-04-08 | Lg Electronics Inc. | Apparatus for energy recovery of a plasma display panel |
US7518574B2 (en) | 2003-10-20 | 2009-04-14 | Lg Electronics Inc. | Apparatus for energy recovery of plasma display panel |
US20050104531A1 (en) * | 2003-10-20 | 2005-05-19 | Park Joong S. | Apparatus for energy recovery of a plasma display panel |
US6977471B2 (en) * | 2004-05-11 | 2005-12-20 | Live Wire Enterprises, Inc. | Electroluminescent device |
US20060290289A1 (en) * | 2004-05-11 | 2006-12-28 | Harold Feldman | Electroluminescent device including a programmable pattern generator |
US7230387B2 (en) * | 2004-05-11 | 2007-06-12 | Live Wire Enterprises, Inc. | Electroluminescent device including a programmable pattern generator |
US20050253530A1 (en) * | 2004-05-11 | 2005-11-17 | Harold Feldman | Electroluminescent device |
US20140152621A1 (en) * | 2011-11-11 | 2014-06-05 | Panasonic Corporation | Touch-panel device |
US9001080B2 (en) * | 2011-11-11 | 2015-04-07 | Panasonic Intellectual Property Management Co., Ltd. | Touch-panel device |
Also Published As
Publication number | Publication date |
---|---|
NL7117935A (en) | 1972-07-03 |
BE777481A (en) | 1972-06-29 |
DE2165424B2 (en) | 1977-07-21 |
DE2165424C3 (en) | 1978-03-23 |
DE2165424A1 (en) | 1972-07-13 |
CA947372A (en) | 1974-05-14 |
BR7108645D0 (en) | 1973-07-03 |
IT951617B (en) | 1973-07-10 |
SE7116687L (en) | 1972-06-30 |
JPS4862387A (en) | 1973-08-31 |
FR2120927A5 (en) | 1972-08-18 |
GB1382256A (en) | 1975-01-29 |
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