JPH0727597Y2 - Electroluminescence - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to electroluminescence (hereinafter abbreviated as EL), and more particularly to an EL incorporated as a backlight on the back side of a liquid crystal display device.

[Conventional technology]

FIG. 2 is a sectional view showing the basic structure of a distributed EL. In the figure, EL1 is a combination of the EL element 2 and a pair of sealing films 3, 4
The seal film 3 has a light-transmitting property. Also, the EL element 2 is on one side
A transparent sheet 6 having a transparent electrode 5 formed of an ITO film or the like
And a light emitting layer 7 in which a phosphor is dispersed in an organic binder
And a counter electrode 8 made of a metal foil or the like are laminated. By connecting a terminal (not shown) to an AC power source and applying a predetermined voltage between both electrodes 5 and 8, the light emitting layer 7 emits light. Can be made. Then, the light of the light emitting layer 7 passes through the transparent electrode 5, the transparent sheet 6 and the sealing film 3 and is emitted to the outside.
It becomes the light emitting surface of.

In recent years, this type of EL has been widely used as a backlight for a liquid crystal display device. That is, as shown in FIG. 3, by incorporating EL1 on the rear surface 11 side of the liquid crystal display device 10, the EL1
The light emitted from the outer surface 3a of the sealing film 3, which is the light emitting surface, is visible from the display surface 12 side of the liquid crystal display device 10.

[Problems to be solved by the device]

By the way, as the sealing film 3 for covering the transparent electrode 5 side of the EL1, generally, trifluoroethylene chloride, which is transparent, rich in moisture proof and excellent in processability, is used, and EVA-based adhesive is applied to one side thereof. The EL element 2 is hermetically covered by stacking the laminated layers with a sealing film 4 made of, for example, an aluminum composite film and heat-sealing the peripheral edge portion. However, since the outer surface 3a of the sealing film 3 made of trifluoroethylene chloride is glossy, it functions as an optical plane, and the outer surface 3a
Since it is difficult to make a complete surface contact with the back surface 11 of the liquid crystal display device 10, there is a problem that a black speckled striped pattern called Newton's ring is visually observed from the display surface 12 side of the liquid crystal display device 10. Atsuta

Further, in the conventional EL1, the local unevenness of the light intensity of the EL element 2 itself may be seen, and the reddishness when not lit is too strong due to the dyeing type, and the improvement thereof is also desired. .

Therefore, the object of the present invention is to solve the above-mentioned problems of the prior art, prevent uneven light intensity such as Newton's ring, and be suitable as a backlight for liquid crystal display devices.
To provide.

[Means for Solving the Problems]

In order to achieve the above object, the present invention provides the transparent electrode in the electroluminescence in which a transparent electrode, a counter electrode, and a light emitting layer interposed between these electrodes are hermetically covered with a pair of sealing films. While integrally forming an adhesive layer on the entire one surface of the sealing film covering the side, roughening the entire outer surface of each of the sealing film and the adhesive layer, the portion of the adhesive layer facing the transparent electrode It is characterized in that the pair of sealing films are joined by heat-sealing the removed peripheral edge portion.

[Action]

With the above structure, since the outer surface of the sealing film covering the transparent electrode side does not form an optical plane for the liquid crystal display device, Newton's ring does not occur, and the adhesive layer of the sealing film is not formed. Since the surface is also roughened, the unevenness of the light intensity of the EL element itself is difficult to see from the outside.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a partially enlarged sectional view of an EL according to an embodiment of the present invention, in which reference numeral 9 denotes an adhesive layer laminated on one side of a sealing film 3, and a portion corresponding to FIG. Are denoted by the same reference numerals and redundant description will be omitted as appropriate.

As is apparent from FIG. 1, this EL1 has a depth of 10 at the outer surface 3a of the sealing film 3 covering the transparent electrode 5 side of the EL element 2.
An unevenness of about 10 μm is formed on the surface 9a of the adhesive layer 9 laminated on the other surface of the sealing film 3 as well. That is, the sealing film 3 made of trifluoroethylene chloride becomes an optical flat surface on the back side of the liquid crystal display device (not shown) unless surface treatment is performed, and a Newton ring is generated, but the outer surface 3a Since it does not become an optical flat surface when used after roughening, the Newton ring does not occur even when pressed against the back surface of the liquid crystal display device. The EVA-based adhesive layer 9 integrally formed on the lower surface of the sealing film 3 in the drawing is for sealing the peripheral portions of both sealing films 3 and 4, and therefore the outer surface of the adhesive layer 9 is not covered. It will be difficult to bring the surface contact with the transparent sheet 6 on which the transparent electrode 5 is formed. However, since the outer surface of the adhesive layer 9 is also roughened, Newton's rings do not occur at that portion, and the unevenness of the light intensity of the EL element 2 itself becomes difficult to see from the outside, and at the time of non-lighting. Since the redness, which is the color of the light emitting layer 7, is softened, the defect rate is reduced and the quality is improved.

As a method of roughening both surfaces of the sealing film 3 with the adhesive layer 9, for example, passing between a pair of upper and lower rollers having fine irregularities on the surface may be performed.

[Effect of device]

As described above, in the EL according to the present invention, since the outer surface of the sealing film covering the transparent electrode side is roughened,
Even if this EL is incorporated as a backlight for a liquid crystal display device, there is no risk of generating a Newton's ring, and the surface of the adhesive layer integrally formed on the other surface of the sealing film is also roughened. However, it is possible not only to prevent the occurrence of Newton's rings, but it is also possible to expect the effect that the unevenness of the light intensity of the EL element itself becomes difficult to see from the outside, and the reddishness of the light emitting layer becomes inconspicuous when not illuminated even with the dyed type. .

[Brief description of drawings]

FIG. 1 is a partially enlarged sectional view of an EL according to an embodiment of the present invention,
FIG. 2 is a sectional view for explaining the basic structure of an EL, and FIG. 3 is an explanatory view showing an EL incorporated as a backlight for a liquid crystal display device. 1 ... EL, 2 ... EL element, 3 ... sealing film, 3a ...
Outer surface (light emitting surface), 5 ... Transparent electrode, 9 ... Adhesive layer.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-62-76187 (JP, A) JP-A-1-315992 (JP, A) Actual opening Sho-62-160499 (JP, U) Actual opening Sho-62- 127698 (JP, U) Actual public Sho 59-7750 (JP, Y2) Actual public Sho 60-164798 (JP, Y2)

Claims (1)

[Scope of utility model registration request] 1. In electroluminescence in which a transparent electrode, a counter electrode, and a light-emitting layer interposed between these electrodes are hermetically covered with a pair of sealing films, the encapsulation covering the transparent electrode side. The adhesive layer is integrally formed on the entire one surface of the film, and the entire outer surface of each of the sealing film and the adhesive layer is roughened, and the peripheral portion of the adhesive layer excluding the portion facing the transparent electrode is heat-sealed. As a result, the pair of sealing films are joined together to provide electroluminescence.