Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1999-09-27
2004-08-10
Hjerpe, Richard (Department: 2674)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C345S204000, C345S206000, C345S068000
Reexamination Certificate
active
06774872
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention generally relates to display devices and more particularly to a light-emitting display device including a plasma display device or an EL (electro-luminescence) display device.
A plasma display device or an EL (electro-luminescence) display device is a flat display device of the light-emission type. One important application of such light-emitting flat display devices is televisions having a very large screen size.
FIG. 1
shows the construction of a plasma display panel
10
of a so-called AC-type PDP (plasma display panel).
Referring to
FIG. 1
, the plasma display panel
10
includes rear-side glass substrate
11
and a front-side glass substrate
15
, wherein the rear-side glass substrate
11
carries thereon a number of addressing electrodes
12
of a Cr/Cu/Cr stacked structure in the form of parallel bands extending in a column direction. Further, a dielectric layer
13
of a low-melting glass is deposited on the substrate
11
so as to cover the addressing electrode
12
, and a rib structure
14
also of a low-melting glass is formed on the dielectric layer
13
such that the rib structure
14
includes a number of ribs each extending in the column direction such that a pair of the ribs are disposed at both lateral sides of each of the addressing electrodes
12
. In the groove thus formed between a pair of the ribs, there is formed a layer of fluorescent material for the three primary colors of red (R), green (G) or blue (B), wherein the grooves for red, green and blue constitute together a single pixel.
On the front-side glass substrate
15
, more precisely on the bottom principal surface of the front-side glass substrate
15
(see FIG.
1
), there are provided a number of display electrodes
16
of a transparent conductive material such as ITO (In
2
O
3
·SnO
2
) in the form of parallel bands, wherein each of the display electrodes
16
extends in a row direction, which is perpendicular to the column direction. Further, a bus electrode
17
of the Cr/Cu/Cr structure extends on each of the display electrodes with a width substantially smaller than a width of the display electrode
16
, and there is formed a dielectric film
18
of a low-melting glass on the substrate
15
so as to cover the display electrodes
16
and the bus electrodes
17
thereon. Further, there is provided a protective film
19
of MgO on the dielectric film
18
.
The glass substrate
11
and the glass substrate
15
having such a construction are assembled such that the ribs
14
on the glass substrate
11
face the protective film
19
on the glass substrate
15
as represented in
FIG. 1
, and an inert gas such as Ar is confined between the space formed between the substrate
11
and the substrate
15
.
In operation, a drive voltage is applied between a selected addressing electrode
12
and a selected display electrode
17
, and the plasma induced as a result of the drive voltage causes a light emission in the predetermined fluorescent layers.
Because of the active, light-emitting nature of the plasma display panel, a plasma display device that uses such a plasma display panel requires a power drive circuitry for driving the plasma display panel, wherein such a power drive circuitry of a plasma display panel consumes an electric power far larger than the electric power that is consumed by a drive circuit of a liquid crystal panel. The same applies true also in other active type flat display device such as the one that uses an ELP (electro-luminescent panel) for the display panel.
In such a light-emitting flat display device, it is required that the number of the addressing electrodes
12
and/or the displaying electrodes
16
has to be increased in order to improve the resolution of representation, while this means that it is necessary to provide the driver integrated circuit chips constituting the power drive circuitry along the peripheral part of the display device with an increased mounting density.
For example, it is necessary, in the case of designing a 42-inch full-color plasma display device that has a resolution of 850×480 pixels, to provide the addressing electrodes
12
in total of 2550 (=850×3; 850 for each of R, G and B), in addition to the display electrodes
16
provided with the number of 480. Thus, when the drive circuitry is formed by using the integrated circuit chips each having 60 output terminals, it is necessary to arrange 40 or more integrated circuit chips side by side in the lateral direction or row direction of the display panel. The number of the required integrated circuit chips increases further when a higher resolution is desired.
In view of the foregoing, various constructions are proposed for achieving the desired dense arrangement of the driver integrated circuit chips.
FIGS. 2 and 3
respectively show conventional constructions
20
and
20
A for mounting the driver integrated circuit chips, wherein those parts in
FIGS. 2 and 3
corresponding to the parts described previously are designated by the same reference numerals and the description thereof will be omitted.
Referring to
FIG. 2
showing the construction
20
known as COB (chip-on-board), a driver integrated circuit chip is mounted directly on a printed circuit board for electrical interconnection. Thereby, the integrated circuit chips can be mounted with an increased density as compared with the case of mounting the same chips in the form accommodated in a package.
Referring to
FIG. 2
, the conventional construction
20
includes a printed circuit board
23
behind the glass substrate
11
and a driver integrated circuit chip
21
mounted on the printed circuit board
23
, wherein the printed circuit board
23
is connected electrically to the addressing electrodes
12
or the bus electrodes
17
on the glass substrate
11
or on the glass substrate
15
via a flat cable
22
′.
In the construction
20
of
FIG. 2
, the driver integrated circuits can be mounted on the printed circuit board
23
with high density. On the other hand, the printed circuit board
23
has a poor thermal conductivity due to the material used therefor, and because of this, the construction
20
has a drawback of poor heat dissipation. Thus, in the construction
20
, there is a problem in that not only the driver integrated circuit chip
21
but also the printed circuit board
23
itself experiences a severe temperature rise, while such a severe temperature rise of the printed circuit board
23
raises a question with regard to the reliability of the printed circuit
23
itself or with regard to the reliability of other driver integrated circuits held on the printed circuit board
23
.
On the other hand, the construction
20
A of
FIG. 3
is known as COG (chip-on-glass), which is under investigation particularly with regard to the art of liquid crystal display device for a high density mounting of the driver integrated circuit chips with reduced thickness. In the field of the liquid crystal display devices, there are reports that the COG construction
20
A is used in practice.
Referring to
FIG. 3
, it should be noted that the driver integrated circuit chip
21
is attached to the glass substrate
11
, and the driver integrated circuit
21
thus mounted on the substrate
11
is connected to the addressing electrodes
12
or to the bus electrodes
17
via bonding wires
21
a
and a flat cable
22
. In the illustrated example, the flat cable
22
carries a connector
22
A at a tip end thereof, and the connector
22
A is used to electrically connect the flat cable
22
to the printed circuit board
23
that is provided at the rear side of the substrate
11
. The printed circuit board
23
may carry integrated circuit chips
24
and
25
containing therein various control circuits.
In the construction
20
A of
FIG. 3
, it should be noted that the driver integrated circuit chips
21
are aligned on the glass substrate along the edge part thereof with a large mounting density. In such a structure of
FIG. 3
, the dissipation of heat from the driver integrated
Aoki Masami
Kawada Toyoshi
Fujitsu Limited
Hjerpe Richard
Nguyen Kimnhung
Staas & Halsey , LLP
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