Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
2001-07-25
2003-04-22
Ball, Michael W. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S299000, C156S154000, C313S505000, C313S506000, C313S112000, C315S169300, C257S088000, C445S025000
Reexamination Certificate
active
06551440
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of manufacturing a color electroluminescent display apparatus applied to various types of thin-plate display apparatuses, and a method of bonding light-transmitting substrates used for the same.
2. Description of the Related Art
An electroluminescent (hereinafter, abbreviated as “EL”) display apparatus is a thin display apparatus capable of matrix display like a liquid crystal display apparatus. The EL display apparatus comprises a plurality of EL devices arranged on a substrate. Each of the EL devices comprises an EL light emission layer interposed between a pair of electrodes, and acts as a picture element of the EL display apparatus. When a so-called high alternating field is generated between the pair of electrodes, the EL light emission layer causes electroluminescence, so that light is emitted from the EL light emission layer. This light is so-called EL light. That is, unlike the liquid crystal display apparatus, the EL display apparatus is of a self-light-emission-type display apparatus that is constituted only by solid-state devices. Moreover, compared to the liquid crystal display apparatus, the EL display apparatus is high in contrast and excellent in legibility. Since the EL display apparatus has the above-mentioned characteristics that cannot be obtained from the liquid crystal display apparatus, research thereon is being widely performed. In recent years, research has been performed on the achievement of a thin-film EL display apparatus capable of color display. The thin-film EL display apparatus, which is a type of the EL display apparatus, uses so-called thin-film EL devices as the EL devices.
The applicant has proposed a first prior art regarding the achievement of an EL display apparatus capable of color display in Japanese Examined Patent Publication JP-B2 3-77640 (1991). A color EL display apparatus using thin-film EL devices according to the first prior art has a structure such that three kinds of EL light emission layers that emit light beams of wavelengths of red, green and blue by electroluminescence, respectively, are arranged in parallel and the EL light emission layers are each sandwiched between a pair of electrodes. In order to put the color EL display apparatus to practical use, it is necessary for the EL light emission layers to emit light beams of the wavelengths with a brightness necessary for matrix display. Generally, the wavelength and the brightness of the light emitted from an EL light emission layer by electroluminescence depends on the material of the EL light emission layer. Since there are few materials that emit light beams of the wavelengths of red, green and blue with the above-mentioned brightness, it is difficult to realize the color EL display apparatus.
A second prior art regarding the achievement of a color EL display apparatus is disclosed in Japanese Unexamined Patent Publication JP-A 64-40887 (1989). The color EL display apparatus of this prior art includes a plurality of thin-film EL devices of a double insulation structure including a light emission layer that emits so-called white light by electroluminescence, and a plurality of organic color filters each transmitting light of the wavelength of only one of red, green and blue. The color filters are each placed directly on one electrode of the pair of electrodes of each thin-film EL device. The white light emitted from each EL device is divided into spectra by the color filters. Consequently, light beams of the wavelengths of red, blue and green exit from the color EL display apparatus.
The thin-film EL devices of the double insulation structure in which thin-film insulation layers are interposed between the electrodes and the light emission layers has a structure such that a multiplicity of thin film pieces are laminated. In forming the film pieces, a defect such as a pinhole is sometimes caused in the film pieces. In the case where the insulation layer has a defect such as a pinhole, when the high alternating field is created between the pair of electrodes of the thin-film EL devices, an electrical breakdown is caused at the pinhole and in the vicinity thereof, so that a microdischarge is caused. There are cases where the color filters on the electrodes deteriorates and breaks due to the microdischarge.
As a third prior art regarding the achievement of a color EL display apparatus, Japanese Unexamined Patent Publication JP-A 64-40888 (1989) discloses an art to prevent the above-mentioned deterioration and breakage of the color filters.
FIG. 20
is an enlarged partial cross-sectional view of a color EL display apparatus
1
according to this prior art. The color EL display apparatus
1
comprises a main substrate
3
, a light-transmitting substrate
4
, a plurality of thin-film EL devices
5
of the double insulation structure, a plurality of color filters
6
and a sealing portion
7
. The thin-film EL devices
5
are arranged on one surface
9
of the main substrate
3
. The color filters
6
are arranged on one surface
10
of the light-transmitting substrate
4
. The main substrate
3
and the light-transmitting substrate
4
are disposed so that the surfaces
9
and
10
are opposed with a predetermined gap in between. The sealing portion
7
, which is so-called passivation protecting means, is disposed between the main substrate
3
and the light-transmitting substrate
4
.
The method of manufacturing the color EL display apparatus
1
will briefly be described below. First, a plurality of lower electrodes
11
which are thin film strips are formed on the one surface
9
of the substrate
3
. Then, a lower insulation layer
12
, a light emission layer
13
and an upper insulation layer
14
are successively laminated in this order on all the lower electrodes
11
. Then, a plurality of upper electrodes
15
which are thin film strips are formed on the upper insulation layer
14
. The upper electrodes
15
each transmit light. The direction of length of the lower electrodes
11
and the direction of length of the upper electrodes
15
are perpendicular to each other when viewed from the direction of the normal
16
to the one surface
9
of the substrate
3
. The portions where the lower electrodes
11
and the upper electrodes
15
intersect when viewed from the direction of the normal
16
are the thin-film EL devices
5
. In order to improve the crystallinity of the light emission layer
13
, after the light emission layer
13
is formed or after the upper insulation layer
14
is formed, annealing is performed in a vacuum or in an inert gas.
Then, the color filters
6
are formed on the one surface
10
of the light-transmitting substrate
4
. Then, the substrate
3
and the light-transmitting substrate
4
are bonded by an epoxy resin
17
so that the surfaces
9
and
10
are opposed with the predetermined gap in between. Lastly, in order to form a protective material layer
18
, the gap between the substrate
3
and the light-transmitting substrate
4
is filled with a gaseous or a liquid protective material. The epoxy resin
17
and the protective material layer
18
constitute the sealing portion
7
. By the above-described process, the color EL display apparatus is completed.
Generally, the inactivation protecting means, that is, the sealing portion
7
is provided for shielding the thin-film EL devices from the atmosphere to thereby stabilize the thin-film EL devices and protecting the thin-film EL devices from mechanical failures. A so-called seal life which is one of the greatest characteristics of typical EL display apparatuses depends on the structure of the sealing portion.
A sealing portion currently used in a typical thin-film EL display apparatus is formed by use of a sealing substrate and a mixture liquid of silica gel and silicone oil. The process of forming the currently-used sealing portion will be described below. The typical thin-film EL display apparatus comprises a plurality of EL devices arranged on one surface of a substrate. First, a concave p
Ball Michael W.
Nixon & Vanderhye P.C.
Rossi Jessica
Sharp Kabushiki Kaisha
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