Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
2000-02-29
2004-08-03
Wu, Xiao (Department: 2674)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
C313S503000
Reexamination Certificate
active
06771236
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to a display panel and a display device to which the display panel is applied. More specifically, it relates to a display panel having a fluorescence layer which is excited by electrons from a vacuum space to emit light, and a display device into which the display panel is incorporated.
Various flat type (flat panel type) displays are being studied as image display devices which are to replace currently main-stream cathode ray tubes (CRT). The flat type displays include a liquid crystal display (LCD), an electroluminescence display device (ELD) and a plasma display panel (PDP). Further, there is also proposed a cold cathode field emission display device, a so-called field emission device (FED), which is capable of emitting electrons into vacuum from a solid without relying on thermal excitation, and it attracts attention from the viewpoint of a brightness on a screen and a low power consumption.
FIG. 24
shows a typical configuration of FED, in which a display panel
500
and a rear panel
400
are placed to be opposed to each other. These panels
400
and
500
are bonded to each other in circumferential end portions through a frame (not shown), so that vacuum space VAC is formed in a closed space between these two panels. The rear panel
400
has cold cathode field emission devices (to be referred to as “field emission devices” hereinafter) as electron emitting members. In
FIG. 24
, there is shown a so-called Spindt type field emission device having a conical electron emitting portion
45
as an example of the field emission device. The Spindt type field emission device comprises a cathode electrode
41
formed on a supporting member
40
, an insulating interlayer
42
formed on the cathode electrode
41
and the supporting member
40
, a gate electrodes
44
formed on the insulating interlayer
42
, and the conical electron emitting portion
45
formed in opening portions
43
provided in the gate electrodes
44
and the insulating interlayer
42
. Generally, a predetermined number of the electron emitting portions
45
having a predetermined alignment are so arranged as to correspond to one fluorescence layer
51
to be explained later. A relatively negative voltage (video signal) is applied to the electron emitting portion
45
from a cathode electrode driving circuit
46
through the cathode electrode
41
, and a relatively positive voltage (scanning signal) is applied to the gate electrode
44
from a gate electrode driving circuit
47
. Electrons are emitted from the top of the electron emitting portion
45
depending upon an electric field generated by the application of these voltages. The electron emitting member is not limited to the above Spindt type field emission device. A so-called edge type field emission device is used in some cases, and other types such as a flat type field emission device, a crown type field emission device and the like are also used in some cases. Further, sometimes the above is the other way round, that is, a scanning signal is inputted to the cathode electrode
41
, and a video signal is inputted to the gate electrode
44
.
The display panel
500
has a plurality of fluorescence layers
51
formed on a transparent substrate
50
composed of glass or the like, and a conductive reflective film
52
. The fluorescence layer
51
is formed in the form of a matrix or stripes, and the conductive reflective film
52
is formed on the fluorescence layer
51
and the transparent substrate
50
. A positive voltage higher than the positive voltage applied to the gate electrode
44
is applied to the conductive reflective film
52
from an acceleration power source (anode electrode driving circuit)
53
, and the conductive reflective film
52
works to direct electrons emitted into the vacuum space VAC from the electron emitting portion
45
toward the fluorescence layer
51
. Further, the conductive reflective film
52
has the following functions. It protects fluorescence particles constituting the fluorescence layer
51
from the sputtering by particles such as ions, it reflects light emitted by the fluorescence layer
51
due to electron excitation toward the transparent substrate
50
to improve the brightness of a display screen viewed from outside the transparent substrate
50
, and it also prevents an excess charge to stabilize the potential of the display panel
500
. That is, the conductive reflective film
52
has both the function of an anode electrode and the function of a member known as a metal-back layer in the field of cathode ray tubes (CRT). The conductive reflective film
52
is generally composed of an aluminum thin film.
FIG. 25A
shows a schematic plan view of a display panel in which the fluorescence layers
51
R,
51
G and
51
B are formed in a matrix form, and
FIG. 25B
shows a schematic partial cross-sectional view taken along an X—X line in
FIG. 25A. A
region where the fluorescence layers
51
R,
51
G and
51
B are arranged is an effective region which practically works as a display device, and an anode electrode forming region corresponds nearly to the above effective region. For clarification, the anode electrode forming region is indicated by slanting lines in
FIG. 25A. A
circumferential region of the effective region is an idle region which supports functions of the effective region such as the housing of peripheral circuits and the mechanical support of a display screen. A lead portion
54
used for connecting the anode electrode to the acceleration power source (see acceleration power source
53
in
FIG. 24
) which supplies a power, for example of 5 kV is formed on an edge portion of the transparent substrate
50
. Between the acceleration power source and the anode electrode is generally provided a resistance member (a resistance value of 100 M&OHgr; in a shown example) for preventing an over-current and discharging. The resistance member is provided outside the substrate.
The anode electrode in an FED is not so necessarily required to be composed of the conductive reflective film
52
as described above. As is shown in a schematic partial cross-sectional view of
FIG. 25C
taken along an X—X line in
FIG. 25A
, there may be employed a constitution in which a transparent conductive film
55
formed on the transparent substrate
50
has the function of the anode electrode. The region where the conductive reflective film
52
or the transparent conductive film
55
which works as an anode electrode is formed covers nearly the entire area of the effective region on the transparent substrate
50
.
FIG. 26A
shows a schematic plan view of a display panel in which the fluorescence layers are formed in a stripe form, and
FIGS. 26B and 26C
show schematic partial cross-sectional views taken along an X—X line in FIG.
26
A. Some members in
FIGS. 26A
to
26
C are the same as those in
FIGS. 25A
to
25
c
and indicated by the same reference numerals, and detailed explanations thereof are omitted.
FIG. 26B
shows a configuration in which the anode electrode is composed of a conductive reflective film
52
.
FIG. 26C
shows a configuration in which the anode electrode is composed of a transparent conductive film
55
. The region where the conductive reflective film
52
or the transparent conductive film
55
which works as an anode electrode is formed covers nearly the entire area of the effective region of the display panel.
Meanwhile, an FED which is a flat type display device has a far smaller flying distance of electrons than a cathode ray tube, so that the electron acceleration voltage cannot be so increased as a cathode ray tube. That is, when the electron acceleration voltage is too high in the FED, a spark discharge is liable to take place very easily between the electron emitting portion on the rear panel and the film which works as an anode electrode, which may highly possibly downgrade the image quality to a large extent. In the discharge generating mechanism in a vacuum space, presumably, a small discharge is first trigg
Igarashi Takahiro
Konishi Morikazu
Kusunoki Tsuneo
Ohno Katsutoshi
Okita Masami
Kananen Ronald P.
Nguyen Kevin
Rader & Fishman & Grauer, PLLC
Sony Corporation
Wu Xiao
LandOfFree
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