Claims:CLAIMS

We claim:
1. An electroluminescent display device(101)comprising:

a first layer(1);

a second layer(5) located under the first layer;

a third layer (3) located under the second layer;

a fourth layer (4) located under the third layer;and

a housing to encapsulate said first layer(1), second layer(5), third layer(3) and fourth layer(4);

wherein;
the second layer(5) acting as a capacitive layer comprises of an ion induced layer (5a) sandwiched between two dielectrics (5b,5c);

theelectroluminescent display device(101)illuminates at a power supply ranging from 0-230Vrmsand frequency ranging from 50-60 Hz;

the electroluminescent display device(101) has a dielectric constantin the rangeof 1400-1600 F/M; and

theelectroluminescent display device(101)operates at a power supply in the range of 22-23 mw cm2 and exhibits a brightnessin the range of 100 to 120 cd/m.

2. The device (101)as claimed in claim 1, wherein, the first layer(1)acts as a conductive layerand is made up of a material includingbut not limited to silver nanoparticles ink.

3. The device (101)as claimed in claim 1, wherein, thethird layer(3) acts as an active layer and is made up of a material including but not limited to doped zinc sulphide.

4. The device (101)as claimed in claim 1, wherein, thefourth layer(4)is a substrate and is made up of a materialincludingbut not limited to ITO.

5. The device(101) as claimed in claim 1, wherein, the housing is layered and made of a material includingbut not limited to a ceramic based ink.

6. The device (101)as claimed in claim 1, wherein, the ion induced layer(5a) of said second layer(5)is made of a materialincluding but not limited to polydiallyldimethylammonium chloride.

7. The device (101) as claimed in claim 1, wherein, the dielectrics (5b, 5c) of said second layer (5) are made of a material including but not limited to calcium copper titanate.
, Description:FIELD OF THE INVENTION
The present invention relates to a novel electroluminescent display device. More particularly, the present invention relates to an electroluminiescent display device having a capacitive layer to illuminate the device at low frequency and helps in lowering the power consumption with optimum brightness having inverter free applications.

BACKGROUND OF THE INVENTION
An electroluminescent display device is a flat panel display created by sandwiching a thin film of electroluminescent material between two plates.The device is similar to capacitor that consists of an electroluminescent material inserted among two plates where one plate is layered and sandwiched with rear/counter and front/transapernt electrodes. In an electroluminescent display device, the atoms in the active layer are moved to an excitation state with the help of electricity that results in radiation being emitted in the form of visible light.By varying excitation level of atoms, the color displayed can be changed in the electroluminescent display.
CN102769955B discloses a high-brightness electroluminescent flat panel display comprising: a conductive metal back layer, the electron-emitting layer, the high dielectric layer, a light emitting layer, an outer layer of a high dielectric, external electron-emitting layer, transparent conductive layer, a transparent conductive layer electrode, the conductive metal back electrode layer, plastic film moisture absorption, fluorine plastic transparent sealing layer; a conductive layer on the metal back electrode and the transparent conductive layer of the electrode voltage AC50-400V added, 0.05-20KHz generate high frequency luminance. The main drawback of the invention is that the display uses very high frequency that leads to excessive use of power and requires an invertor and transformer assembly
CN1747612A discloses an inorganic electroluminescent display device including a substrate, a first electrode formed on the substrate, a first insulation layer formed on the first electrode, a luminescent layer formed on the first insulation layer, a second insulation layer formed on the luminescent layer, and a second electrode formed on the second insulation layer. A diffraction grid is provided at atleast one of a first interface between the first insulation layer and the luminescent layer and a second interface between the second insulation layer and the luminescent layer. The main drawback of the invention is that the diffraction grid formed has protrusions that limits the wavelength of the light.
CN(101)754511A discloses lower conducting dome of an inorganic electroluminescent display, wherein the material of the lower conducting dome is Ti-Au composite film and also provides a method of manufacturing a bottom electrode in non-organic electroluminescent displays, TFT glass substrate is first blown dry cleaned, the glass substrates were placed in an electron beam evaporation apparatus, applying vacuum to 1.5x10-3Pa-3.0x10-3Pa air pressure, the glass substrate temperature was heated to 130-180°C, the evaporation rate wasusing a Ti target with an electron beam evaporation and the plated onto 45-thick Ti film and then the Au target goes to the evaporation position also deposited on the 140-thick Au film is removed from the vacuum chamber gas amplification glass substrate, the bottom electrode in forming the completed. The main drawback of the invention is the high cost of materials used in formation of composite.
Therefore, there is a need to develop a cost effective inorganic electroluminescent display device that operates under low frequency and consumes less power.

OBJECT OF THE INVENTION
The main object of the present invention is to provide an electroluminescent display device having a capacitive layer to illuminate the device at low frequency and provides high brightness and further having inverter free applications.
Another object of the present invention is to provide an electroluminescent display device having a capacitive layer to form a high capacitance based capacitor.
Yet another object of the present invention is to provide an electroluminescent display device having a capacitive layer comprising of an ion induced layers which is sandwiched between the two dielectrics.
Still another object of the present invention is to provide an electroluminescent display device with a plurality of layers that are screen printed over one another,annealed and further encapsulated to form a housing of an efficient capacitor.

SUMMARY OF THE INVENTION
The present invention relates to an electroluminescent display device.More particularly, the present invention relates to an electroluminiescent display device having a capactive layer to illuminate at low frequency and power consumption in the range of 2-3 mW cm2with brightness ranges from 100 to 120 cd/m.
In a main embodiment, the present invention provides an electroluminescent display device comprising a first layer acting as a conductive layer; a second layer acting as a capacitive layer located under the first layer; a third layer acting as an active layer located under the second layer; a fourth layer acting as a substrate located under the third layer and said layers are fused together and encapsulated to form a housing of an electroluminsescent display device; wherein,the first layer acting as a conductive layer is made up of materials including but not limited to silver nanoparticles ink;the second layer comprises of an ion induced layer sandwiched between the two dielectrics; the third layer acting as an active layer made of materials including but not limited to doped zinc sulphide; the fourth layeracting as a substrate is made up of material including but not limited to ITO; the housing is layered and made by material including but not limited to ceramic based ink; said device illuminates at a power supply ranging from 0-230Vrmsand frequency ranging from 50-60 Hz; and said device has a dielectric constant in the range of 1400-1600 F/M.
The present invention provides an electroluminescent display device having a capacitive layer comprising of an ion induced layer sandwiched between two dielectrics. The ion induced layer is made up of material including but not limited to poly diallyldimethylammonium chloride and the dielectric is made of a material including but not limited to calcium copper titanate. The capacitive layer increases the dielectric constantin order of 1400-1600 F/M at 1KHz and increases the capacitance to enable the device to operate under a low frequency ranging from 50-60 Hz with a voltage ranging from 220-230 volts. The device consumes power in the range of 2-3 mW cm2with brightness ranging from 100 to 120 cd/m.

BRIEF DESCRIPTION OF THE DRAWINGS
A complete understanding of the system and method of the present invention may be obtained by reference to the following drawings:
Fig.1 is a perspective view of a conventional electroluminescent display device in accordance with an embodiment of the prior art.
Fig.2 is a perspective view of an electroluminescent display device in accordance with an embodiment of the present invention.
Fig.3 is a process flowchart of preparing an electroluminescent display device in accordance with an embodiment of the present invention.

DETAILEDDESCRIPTION OF THE INVENTION
The present invention will now be described hereinafter with reference to the accompanying drawings in which a preferred embodiment of the invention is shown. This invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiment set forth herein. Rather, the embodiment is provided so that this disclosure will be thorough, and will fully convey the scope of the invention to those skilled in the art.
The present invention relates to an electroluminescent display device.More particularly, the present invention relates to an electroluminiescent display device having a capactive layer to illuminate at low frequency and power consumption in the range of 2-3 mW cm2with brightness ranges from 100 to 120 cd/m.
In a main embodiment, the present invention provides an electroluminescent display device comprising a first layer acting as a conductive layer; a second layer acting as a capacitive layer located under the first layer; a third layer acting as an active layer located under the second layer; a fourth layer acting as a substrate located under the third layer and said layers are fused together and encapsulated to form a housing of an electroluminsescent display device; wherein, the first layer acting as a conductive layer is made up of materials including but not limited to silver nanoparticles ink; the second layer comprises of an ion induced layer sandwiched between two dielectrics; the third layeracting as an active layer made of materials including but not limited to doped zinc sulphide; the fourth layer acting as a substrate is made up of material including but not limited to ITO; the housing is layered and made by material including but not limited to ceramic based ink; said device illuminates at a power supply ranging from 0-230Vrmsand frequency ranging from 50-60 Hz; and said device has a dielectric constant in the range of 1400-1600 F/M.
The present invention provides an electroluminescent display device having a capacitive layer comprising of an ion induced layer sandwiched between two dielectrics. The ion induced layer is made of a material including but not limited to poly diallyldimethylammonium chloride and the dielectric is made of a material including but not limited tocalcium copper titanate. The capacitive layer increase the dielectric constant in order of 1400-1600 F/M at 1kHz and increases the capacitance that enable the device to operate under a low frequency ranging from 50-60 Hz with a voltage ranging from 220-230 volts. The device consumes power in the range of 2-3 mW cm2with brightness ranges from 100 to 120 cd/m.
Now referring to Fig.1, the conventional electroluminescent display device (100)in accordance with a prior art is shown.Said conventional electroluminescent display devicecomprises of a first layer (1) preferably made up of silver, a second layer (2) that acts as a dielectric and preferably made of printed barium titanate located under the first layer (1), a third layer (3) that acts as a light emitting layerand preferably made of doped zinc sulphide located under the second layer (2) and a fourth layer (4) that acts as a substrate located under the third layer. The conventional electroluminescent display device operates at an input alternating voltage of 110 volts with frequency ranging from 2 kHz to 4 kHz using an amplifier and transformer.
Now referring to Fig.2, the perspective view of an electroluminescent display device (101) is shown. Said electroluminescent display device (101) comprises of a first layer (1) acting as a conductive layer made up of a material including but not limited to silver nanoparticles ink, a second layer (5) acting as a capacitive layer is located under the first layer and comprises of an ion induced layer sandwiched between two dielectrics, a third layer (3) acting as an active layer is located under the second layerand is made up of a material that includes but is not limited to doped zinc sulphide; and a fourth layer (4) acting as a substrate islocated under the third layer and is made up of a material that includes but is not limited to transparent ITO. All the layers (1,3,4,5) are sandwiched together and are encapsulated to form a housing using a ceramic based ink. The second layer (5) that acts as a capacitive layer is a multilayer structure and incorporates an ion induced layer (5a)sandwiched between the two dielectrics (5b,5c). The integration of dielectrics (5b,5c)made up of a material including but not limited to calcium copper titanate (CCTO) with the ion induced layer (5a)made of polydiallyldimethylammonium chloride increases the capacitance and the dielectric constantof the second layer (5) in order of 1400-1600 F/M at 1kHz. The increase in capacitance drops the capacitive reactance and the decrease in capacitive reactance excites the photons of layers at low frequency maintaining arequired brightness level. The electroluminescent display device (101) does not use an amplifier or transformer and operates under a low frequency ranging from 50-60 Hz with voltage ranging from 220-230 volts.
In the present invention, when an alternating current is applied to the electroluminescent display device (101), the molecules of the third layer (3) acting as active layes excite to next level thereby releasing photons and the capacitance of the capacitive layer (5)shoots up due to sandwiched structure of polydiallyldimethylammonium chloride(5a)between the two calcium copper titanate (CCTO) dielectrics (5b,5c). The increase in capacitance lowers the frequency and decreases the capacitive reactance. The decrease in capacitive reactance enables the device to operate under low frequency ranging from 50-60 Hz and low power supply ranging from 220-230 volts.
Now referring to Fig.3, aprocess flowchart for preparing the electroluminescent display device (101) is shown. The fourth layer (4)acting as a substrate is subjected to annealing at a high temperature ranging from 100-130 degrees to improve the interatomic spacing and to avoid the shrinking is screen printed on the third layer (3) acting as an active layer and subsequently the third layer (3)is screen printed on the second layer (5). The layers (1,3,4,5) are encapsulated to form a housing using ceramic based ink. The second layer (5) acting as a capacitive layer comprising an ion induced layer (5a)screen printed on the CCTO dielectrics (5b,5c). The integration of ion induced layer (5a)between the two dielectrics (5b,5c)led to increase in the thickness of the electroluminescent display device (101)and this increased thickness avoidsshort circuit and traps occurred due to screen printing. Table 1 provides the comprehensive informationon all the materials used in the layers.

Table 1
Material Information of the layers in Electroluminescent Device
Sl. No Material Chemical Content Source Method of Printing Mesh Size Ink Formulation
1 ITO PET Indium Tin Oxide Sputtered Poly ethylene terephthalate Gus Industries (China) N/A N/A N/A
2 Active/Light Emitting Layer Doped Zinc Sulfide (Phosphor) Advanced Electronic Material Korea Screen Printing 200 TPI Binder, Additive ratio and Phosphor layer is optimized to 50:50
3 Dielectric (CCTO) Calcium copper Titanate Thermograde Process Technology Screen Printing 256 TPI Binder, Additive ratio and Calcium copper titanate is optimized to 50:50
4 Dielectric (PDADMAC) Polydiallyl dimethyl ammonium chloride Sigma-Aldrich Screen Printed 172TPI 20% PDADMAC in Water, Titanium Dioxide Binder, Additives and Surfactants
5 Conductor conductive Silver Ink Advanced Electronic Material Korea Screen Printing 305 TPI N/A
6 Encapsulation Ceramic based ink Henkel Electronic Materials Screen Printing 305 TPI N/A

The conventional electroluminescent display device (100)perceives photon excitation by stimulus of electricity and illuminates at high frequency with the help of an inverter and transformer.The present invention provides an electroluminescent display device (101)having high k dielectric (5b,5c) and an ion induced layer (5a) to form a high capacitance based capacitive layer (5) that illuminates at a low frequency of 50-60 Hz and lower the voltage of 220-230 volts without using inverter.
Many modifications and other embodiments of the invention set forth herein will readily occur to one skilled in the art to which the invention pertain having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.