Electric lamp and discharge devices – With luminescent solid or liquid material – Solid-state type
Reexamination Certificate
1999-03-12
2002-10-29
Patel, Vip (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
Solid-state type
C313S509000
Reexamination Certificate
active
06472816
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electroluminescent module comprising an electroluminescent element as combined with an circuit board, etc.
2. Description of the Related Art
An electroluminescent element comprises a transparent electrode layer of ITO as formed on the back surface of a transparent electrode film that is positioned in the front, in which a light-emitting layer, a dielectric layer and a back electrode layer are formed in that order on the back surface of the transparent electrode layer. With that constitution, an electroluminescent element is electrically connected with a circuit board, on which is mounted the electroluminescent element or a driving circuit for a portable electronic appliance as connected with the electroluminescent element, by connecting each electrode part of the transparent electrode layer and the back electrode layer of the electroluminescent element with the circuit pattern or the flexible print cable (FPC) as formed on the circuit board.
Integrating an electroluminescent element with a circuit board or the like in the manner mentioned above gives an electroluminescent module, which is built in various electronic appliances. For example, an electroluminescent element is much used as the backlight for the switch key and the display part of portable telephones, in which an electroluminescent element is fitted to and electrically connected with a circuit board provided with a driving circuit in such a manner that the electrode parts of the electroluminescent element are connected with the connecting pattern of the circuit board.
FIG.
3
A and
FIG. 3B
show interconnection structures of the electrode parts of a conventional electroluminescent module. In
FIG. 3A
, the electrode part
43
a
is in the side of the transparent electrode layer. In
FIG. 3B
, the electrode part
43
b is in the side of the back electrode layer. In those, the front of the circuit board
41
(upper surface in FIG.
3
A and
FIG. 3B
) is provided with a connecting pattern (not shown), and an electroluminescent element is fitted thereto via a conductive adhesive
42
a
. On the back surface of the transparent electrode film
44
of the electroluminescent element, formed is a transparent electrode layer
45
. In the part that is to be the electrode part
43
a
, a conductive layer
46
is formed on the back surface of the transparent electrode layer
45
. While pressing a hot iron against the electrode part
43
a
, the connecting pattern is electrically connected with the transparent electrode layer
45
via the conductive adhesive
42
a.
FIG. 3B
shows the electrode part
43
b
in the side of the back electrode layer. In this, an electroluminescent element is fitted under pressure to the connecting pattern as formed on the circuit board
41
in a position different from that of the electrode part
43
a
in the side of the transparent electrode layer, via a conductive adhesive
42
b
. The electroluminescent element comprises a light-emitting layer
47
, a dielectric layer
48
and a back electrode layer
49
as formed on the back surface of the transparent electrode layer
45
formed on the back surface of the transparent electrode film
44
. In the region to be the connecting electrode part, the light-emitting layer
47
is not formed. In that region, formed is a dielectric layer
48
to fill it, by which the contact of the transparent electrode layer
45
with the back electrode layer
49
is blocked. Under thermal pressure, the connecting pattern is electrically connected with the back electrode layer
49
via the conductive adhesive
42
b
therebetween.
As mentioned hereinabove, when each electrode part is connected with the connecting pattern under thermal pressure, the part against which a hot iron for thermal pressure is pressed is heated at high temperature of 160 C or higher. Therefore, that part thus heated under pressure shall receive residual peeling stress and external peeling force, whereby the electrode part in the side of the transparent electrode layer will be cracked or the transparent electrode layer and the electrode part will be delaminated at the boundary therebetween. Such cracking and delamination will often cause electrical interconnection failure. Also in the electrode part in the side of the back electrode layer, the transparent electrode layer and the back electrode layer will be delaminated at the boundary therebetween owing to the residual peeling stress and the external peeling force.
In the related art, the position at which the electroluminescent element is fitted to the circuit board differs from that at which each electrode part is connected with the circuit pattern, which, however, requires different steps for the fitting and the connection in different positions, thereby causing the increase in the production costs. In that, in addition, since the electrode interconnection area differs from the electroluminescent element-fitting area, a large space is needed for those areas, and the electroluminescent element fitting to the circuit board could not be well balanced with the electrode interconnection on the board. This brings about still another problem in that the fitting of the electroluminescent element to the circuit board is often unstable.
SUMMARY OF THE INVENTION
To solve the problems noted above, the electroluminescent module of the invention comprises an electroluminescent element as electrically connected with a circuit board on which is mounted the electroluminescent element or a driving circuit for a portable electronic appliance as connected with the electroluminescent element, and is characterized in that the connecting electrode part in the side of the transparent electrode layer and the connecting electrode part in the side of the back electrode layer are provided in the facing opposite sides of the electroluminescent element, and that the electroluminescent element is electrically connected with the circuit board via the connecting electrode parts by bonding it to the circuit board at those parts. With that constitution, the electroluminescent module of the invention saves any superfluous space of the circuit board to which the electroluminescent element is bonded.
In the electroluminescent module of the invention, a flexible, insulating resin layer is provided in two separate sites both adjacent to the transparent electrode layer in such a manner that the connecting electrode part to be electrically connected with the transparent electrode layer is provided on one insulating resin layer while the connecting electrode part to be electrically connected with the back electrode layer is provided on the other insulating resin layer. In this, these insulating resin layers are to absorb the residual peeling stress and the external peeling force applied to the boundary between the connecting pattern of the circuit board and each connecting electrode of the electroluminescent element so as to prevent the delamination at their boundary, thereby improving the quality of the electroluminescent module.
REFERENCES:
patent: 5844362 (1998-12-01), Tanabe et al.
patent: 0984688 (2000-03-01), None
patent: 58-52635 (1983-11-01), None
patent: 1-194291 (1989-08-01), None
patent: 2-197 (1990-01-01), None
JP 9-35873 English Abstract.
JP 62-111198 English Abstract.
JP 58-52635 English Abstract.
JP 2-197 English Abstract.
JP 1-194291 English Abstract.
Dobuchi Yoshikatsu
Ikeda Hidetsugu
Angotti, Esq. Donna L.
Lutzker, Esq. Joel E.
Patel Vip
Schulte Roth & Zabel
Seiko Precision, Inc
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