Title: Flat lamp with horizontal facing electrodes
Abstract: A flat lamp with horizontal facing electrodes is provided, in which a front substrate and a rear substrate are spaced such as to face each other. Walls between the front and rear substrates form a discharging space filled with a discharge gas. A plurality of front electrodes and a plurality of rear electrodes are provided on facing surfaces of the front and rear substrates, respectively. The front and rear electrodes, formed in strips, are arranged in such a way that the front electrodes alternate with the rear electrodes. Accordingly, the discharging distance between front and rear electrodes is lengthened, and many fine discharging operations occur between tip electrodes extending from the lateral sides of the electrode strips and flat portions of corresponding electrode strips. Therefore, a current concentration is prevented, thereby achieving uniform discharging. Also, brightness of the flat lamp increases.
Patent Number: 6,885,151 Issued on 04/26/2005 to Kim, et al.
| Inventors:
|
Kim; Gi-young (Chungcheongbuk-do, KR);
Park; Hyoung-bin (Kyungki-do, KR);
Im; Seoung-jae (Seoul, KR);
Hong; Ji-hyun (Kyungki-do, KR);
Lee; Yoon-jung (Seoul, KR)
|
| Assignee:
|
Samsung Electronics Co., Inc. (Suwon-Si, KR)
|
| Appl. No.:
|
347456 |
| Filed:
|
January 21, 2003 |
Foreign Application Priority Data
| Jan 19, 2002[KR] | 10-2002-0003193 |
| Current U.S. Class: |
313/631; 313/484; 313/491; 313/631 |
| Intern'l Class: |
H01J 017//04; H01J 001//62 |
| Field of Search: |
313/582-583,484,491,494-495,621,631,243,610
|
References Cited [Referenced By]
U.S. Patent Documents
| 4336535 | Jun., 1982 | Albertine, Jr.
| |
| 4359663 | Nov., 1982 | Shinoda et al.
| |
| 6246171 | Jun., 2001 | Vollkommer et al.
| |
| 6441554 | Aug., 2002 | Nam et al.
| |
| 6628066 | Sep., 2003 | Eberhardt et al.
| |
| Foreign Patent Documents |
| 60044943 | Mar., 1985 | JP.
| |
Other References
Ilmer, M., et al., Hg-free Flat Panel Light Source PLANON®—a Promising
Candidate for Future LCD Backlights, Society for Information Display International
Symposium, Digest of Technical Papers 31, (2000), pp. 931-933.
Ikeda, Y., et al., Mercury-Free, Simple-Structured Flat Discharge LCD Backlights
Ranging from 0.5 to 5.2-in. Diagonals, Society for Information Display International
Symposium, Digest of Technical Papers 31, (2000), pp. 938-941.
Choi, J.Y., et al., Mercury-Free, 18″ class flat fluorescent Lamp with
good uniformity, Proceedings of the 1st International Display Manufacturing
Conference, (2000), pp. 231-232.
|
Primary Examiner: Patel; Nimeshkumar D.
Assistant Examiner: Colón; German
Attorney, Agent or Firm: Burns, Doane, Swecker & Mathis, L.L.P.
Claims
1. A flat lamp with horizontal facing electrodes, the flat lamp comprising:
a front substrate and a rear substrate which are spaced to face each other;
walls between the front and rear substrates to form a discharging space filled
with a discharge gas; and
a plurality of strip-like front electrodes and a plurality of strip-like rear
electrodes which are provided on facing surfaces of the front and rear substrates,
respectively,
wherein the front electrodes and the rear electrodes are arranged alternately
and in parallel,
wherein each of the front and rear electrodes has a plurality of tip electrodes
formed at predetermined intervals, and
the tip electrodes of the front electrode alternate with the tip electrodes of
the adjacent rear electrode.
2. The flat lamp with horizontal facing electrodes of claim 1, wherein the front
or rear electrodes have a plurality of tip electrodes formed at predetermined intervals.
3. The flat lamp with horizontal facing electrodes of claim 2, wherein the tip
electrodes are formed along longitudinal sides of the front or the rear electrode
in such a way that tip electrodes at one longitudinal side alternate with tip electrodes
at the other longitudinal side.
4. The flat lamp with horizontal facing electrodes of claim 1, wherein each of
the electrodes has two unit electrodes disposed side by side.
5. The flat lamp with horizontal facing electrodes of claim 4, wherein a plurality
of tip electrodes are formed at predetermined intervals at the outer longitudinal
sides of the unit electrodes of the front or the rear electrode in such a way that
the tip electrodes at one outer longitudinal side alternate with the tip electrodes
at the other outer longitudinal side.
6. The flat lamp with horizontal facing electrodes of claim 1, wherein each selected
electrode between the front electrode and the rear electrode has two unit electrodes.
7. The flat lamp with horizontal facing electrodes of claim 6, wherein a plurality
of tip electrodes are formed at predetermined intervals at the outer longitudinal
sides of the unit electrodes of the selected electrode in such a way that the tip
electrodes at one unit electrode alternate with the tip electrodes at the other
unit electrode.
8. The flat lamp with horizontal facing electrodes of claim 6, wherein a plurality
of tip electrodes are formed at predetermined intervals on both longitudinal sides
of a non-selected electrode in such a way that the tip electrodes at one side alternate
with the tip electrodes at the other side.
9. The flat lamp with horizontal facing electrodes of claim 1, wherein a dielectric
layer is formed over each of the electrodes.
10. The flat lamp with horizontal facing electrodes of claim 1, further comprising
a reflective layer between the rear substrate and the rear electrodes.
11. A flat lamp with horizontal facing electrodes, the flat lamp comprising:
a front substrate and a rear substrate which are spaced to face each other;
walls between the front and rear substrates to form a discharging space filled
with a discharge gas; and
a plurality of strip-like front electrodes and a plurality of strip-like rear
electrodes which are provided on facing surfaces of the front and rear substrates,
respectively,
wherein the front electrodes and the rear electrodes are arranged alternately
and in parallel, and
wherein the tip electrodes are formed along both longitudinal sides of the front
and the rear electrode in such a way that the tip electrodes at one longitudinal
side alternate with the tip electrodes at the other longitudinal side and that
the tip electrodes of the front electrode alternate with the tip electrodes of
the adjacent rear electrode.
12. A flat lamp with horizontal facing electrodes, the flat lamp comprising:
a front substrate and a rear substrate which are spaced to face each other;
walls between the front and rear substrates to form a discharging space filled
with a discharge gas; and
a plurality of strip-like front electrodes and a plurality of strip-like rear
electrodes which are provided on facing surfaces of the front and rear substrates,
respectively,
wherein the front electrodes and the rear electrodes are arranged alternately
and in parallel,
wherein each of the electrodes has two unit electrodes disposed side by side,
and
wherein a plurality of tip electrodes are formed at predetermined intervals on
the outer longitudinal sides of the unit electrodes of each of the front and the
rear electrodes in such a way that the tip electrodes at one outer longitudinal
side alternate with the tip electrodes at the other outer longitudinal side and
that the tip electrodes at one side of each of the front electrodes alternate with
the tip electrodes at a corresponding side of an adjacent rear electrode.
13. A flat lamp with horizontal facing electrodes, the flat lamp comprising:
a front substrate and a rear substrate which are spaced to face each other;
walls between the front and rear substrates to form a discharging space filled
with a discharge gas; and
a plurality of strip-like front electrodes and a plurality of strip-like rear
electrodes which are provided on facing surfaces of the front and rear substrates,
respectively,
wherein the front electrodes and the rear electrodes are arranged alternately
and in parallel,
wherein each selected electrode between the front electrode and the rear electrode
has two unit electrodes; and
wherein a plurality of tip electrodes are formed at predetermined intervals at
the outer longitudinal sides of the unit electrodes of the selected electrode so
that the tip electrodes at one unit electrode alternate with the tip electrodes
at the other unit electrode; a plurality of tip electrodes are formed at predetermined
intervals on both sides of the non-selected electrode so that the tip electrodes
at one side alternate with the tip electrodes at the other side; and the tip electrodes
of each of the front electrodes alternate with the tip electrodes of an adjacent
rear electrode.
Description
BACKGROUND OF THE INVENTION
This application claims the priority of Korean Patent Application No. 2002-3193,
filed on Jan. 19, 2002, in the Korean Intellectual Property Office, the disclosure
of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a fiat lamp with horizontal facing electrodes,
and more particularly, to a flat lamp with horizontal facing electrodes, in which
electrodes are disposed on front and rear substrates in such a way that the electrodes
on the front substrate do not face the electrodes on the rear substrate, and accordingly
stable discharging occurs and brightness increases.
2. Description of the Related Art
Flat lamps for use as a backlight of a liquid crystal display (LCD) have been
developed from conventional light-edging or light-directing cold cathode fluorescent
lamps to surface discharging type or facing surfaces discharging type plasma lamps.
The surface discharging type or facing surfaces discharging type plasma lamps are
considered and developed in that the entire space under a light emitting diode
serves as a discharging space in order to achieve luminous efficiency, the uniformity
of luminescent brightness, or the like.
Surface discharging type plasma lamps generally provide more stable discharge
characteristics than facing surfaces discharging type plasma lamps, but the brightness
of the former lamps is lower than that of the latter lamps. In an example of a
conventional surface discharging flat lamp (see M. Ilmer et al., Society for Information
Display International Symposium, Digest of Technical Papers 31, 931 (2000)), an
entire discharging area is divided into many fine discharging areas in order to
prevent local concentration of discharge, and stable discharging can be performed.
However, since the uniformity of the entire luminescent brightness is not good
due to the difference in the luminescent brightness between fine discharging areas
and the gap therebetween, this lamp must adopt a diffuser sheet to evenly diffuse light.
FIG. 1 shows another example of a conventional surface discharging flat lamp.
A discharging space, which is filled with a discharge gas, is formed between front
and rear substrates
1 and
2 spaced apart from each other by a wall
7. Discharging electrodes
3 and
4 are formed at both sides
on the inner surface of the rear substrate
2 and each has a dielectric layer
5 formed thereon. A fluorescent layer
6 is formed on the inner surface
of each of the front and rear substrates
1 and
2. It is known (see
Y. Ikeda et al., Society for Information Display International Symposium, Digest
of Technical Papers 31, 938 (2000)) that a surface discharging type flat lamp having
such a structure provides low brightness according to the discharge characteristics.
FIG. 2 shows an example of a conventional facing surfaces discharging type flat
lamp. A wall
7a isolates a front substrate
1a from
a rear substrate
2a by a predetermined interval such that a discharging
space is formed between the front and rear substrates
1a and
2a.
Discharging electrodes
3a and
4a are formed on the
outer surface of the front substrate
1a and the inner surface of
the rear substrate
2a, respectively, such that the discharging electrodes
3a and
4a face each other. A dielectric layer
5a
is formed on the electrode
4a, and a fluorescent layer
6b
is formed on the electrode
4a and on the inner surface of the
front substrate
1a. Such a facing surfaces discharging type flat
lamp (see J. Y. Choi et al., Proceedings of the 1
st International Display
Manufacturing Conference, 231(2000)) provides a higher brightness than the surface
discharging flat lamp of FIG.
1. However, this lamp has a low discharge
efficiency due to excessive flowing of current and performs unstable discharging.
FIG. 3 shows another example of a conventional facing surfaces discharging type
flat lamp. Electrodes
3b and
4b are formed on the inner
surfaces of facing walls
7b so as to face each other. Each of the
electrodes
3b and
4b is protected by a dielectric layer
5b. Also, the facing walls
7b separate the front and
rear substrates
1b and
2b from each other such as to
form a discharging space between the electrodes
3b and
4b.
A fluorescent layer
6b is formed on each of the inner surfaces of
the front and rear substrates
1b and
2b. A facing surfaces
discharging type flat lamp having facing electrodes at a wall can prevent over-flowing
of current, but is prone to have an unstable performance, and particularly, local discharging.
To sum up, conventional flat lamps provide low brightness if they perform stable
discharging. Alternatively, if they have a high brightness, they suffer unstable discharging.
SUMMARY OF THE INVENTION
The invention provides a flat lamp with horizontal facing electrodes, which achieves
stable discharging and has high brightness.
According to an embodiment of the present invention, there is provided
a flat lamp with horizontal facing electrodes, in which a front substrate and a
rear substrate are spaced to face each other. Walls between the front and rear
substrates forms a discharging space filled with a discharge gas. A plurality of
strip-like front electrodes and a plurality of strip-like rear electrodes are provided
on facing surfaces of the front and rear substrates, respectively. Here, the front
and rear electrodes are arranged alternately and in parallel.
Preferably, a plurality of tip electrodes are formed at predetermined
intervals along both longitudinal sides of each of the front or rear electrodes
in such a way that the tip electrodes at one longitudinal side alternate with the
tip electrodes at the other longitudinal side.
It is also preferable that a plurality of tip electrodes are formed at predetermined
intervals along both longitudinal sides of each of the front or rear electrodes
in such a way that the tip electrodes of a front electrode alternate with the tip
electrodes of an adjacent rear electrode.
According to another embodiment of the present invention, each of the electrodes
has two unit electrodes disposed side by side.
According to still another embodiment of the present invention, each selected
electrode between the front electrode and the rear electrode has two unit electrodes.
BRIEF DESCRIPTION OF THE DRAWINGS
The above features and advantages of the present invention will become more apparent
by describing in detail exemplary embodiments thereof with reference to the attached
drawings in which:
FIG. 1 is a schematic cross-section of a conventional surface discharging type
flat lamp;
FIG. 2 is a schematic cross-section of a conventional flat lamp with facing
electrodes at front and rear substrates;
FIG. 3 is a schematic cross-section of a conventional flat lamp with facing
electrodes at walls;
FIG. 4 is a partial cross-section of a flat lamp with horizontal facing electrodes
according to a first embodiment of the present invention;
FIG. 5 is a perspective plan view schematically showing the arrangement of the
electrodes of FIG. 4;
FIG. 6 is a partial cross-section of a flat lamp with horizontal facing electrodes
according to a second embodiment of the present invention;
FIG. 7 is a perspective plan view schematically showing the arrangement of the
electrodes of FIG. 6;
FIG. 8 is a partial cross-section of a flat lamp with horizontal facing electrodes
according to a third embodiment of the present invention; and
FIG. 9 is a perspective plan view schematically showing the arrangement of the
electrodes of FIG. 8.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will now be described more fully with reference to the
accompanying drawings, in which preferred embodiments of the invention are shown.
In the drawings, the thickness of layers or regions is exaggerated for clarity.
FIG. 4 is a partial cross-section of a flat lamp
100 with horizontal
facing electrodes according to a first embodiment of the present invention. FIG.
5 is a perspective plan view schematically showing the arrangement of the electrodes
of FIG.
4. In FIG. 5, dotted electrodes over a rear substrate
120
are electrodes disposed on a front substrate
110.
Referring to FIGS. 4 and 5, a discharging space, which is filled with a
discharge gas, is formed between the front and rear substrates
110 and
120
which are isolated from each other by a wall
140. Electrodes
112
and
122 are formed in strips at predetermined intervals on the facing surfaces
of the front and rear substrates
110 and
120, respectively, in such
a way that the electrodes
112 alternate with the electrodes
122.
Each of the front and rear electrodes
112 and
122 is protected by
a dielectric layer
130, which prevents each of the front and rear electrodes
112 and
122 from contacting a discharge gas. The front electrodes
112 are made of transparent indium tin oxide (ITO). The front and rear electrodes
112 and
122 are connected to an external power source (not shown).
A fluorescent layer
150 is formed on the inner surfaces of the front and
rear substrates
110 and
120 and on the inner surface of the wall
140 and covers the dielectric layer
130. A reflective plate (not
shown) may be interposed between the rear substrate
120 and the fluorescent
layer
150 on the rear substrate
120. A plurality of spacers
160
stand between the front and rear substrates
110 and
120 so as to
maintain a gap therebetween in order to prevent the flat lamp
100 from breaking
due to a difference between inside and outside pressures of the flat lamp
100.
A diffuser sheet
114, for preventing generation of a difference in luminescent
brightness between fine discharging areas, may be further installed on the front
substrate
110.
The front and rear electrodes
112 and
122, formed in strips, have
a plurality of tip electrodes
112a and
122a, respectively.
The tip electrodes
112a are arranged along both sides of the front
electrode
112 in such a way that the tip electrodes on one side alternate
with the tip electrodes on the other side, and likewise for the tip electrodes
122a. As shown in FIG. 5, the tip electrodes
112a and
122a are formed at the front and rear electrodes
112 and
122,
respectively, in such a way that the tip electrodes
112a at a front
electrode
112 alternate with the tip electrodes
112a at an
adjacent rear electrode
122. In other words, a tip electrode
112a
at a front electrode
112 is disposed to face and stably discharge with
a nearest portion with no tip electrodes
122a of a rear electrode
122. The portion with no tip electrodes
122a, with which the
tip electrode
112a discharges, is connected by a horizontal dashed
line starting from the tip electrode
112a of FIG.
5.
A flat lamp according to the present invention operates according to a widely-known
driving method. In a discharging space filled with a discharge gas, plasma discharging
is generated and maintained by a voltage, e.g., an AC voltage, applied between
electrodes
112 and
122. At this time, high temperature electrons
for exciting neutral gas atoms and molecules are generated. Atoms and molecules
excited by the high temperature electrons emit ultraviolet rays while returning
to a normal state, and the emitted ultraviolet rays excite the fluorescent layer
150 coated within the discharging space and generate visible light. In order
to prevent the front electrodes
112 formed on the front substrate
110
from being viewed by viewers, the front electrodes
112 and the dielectric
layers
130 are formed of a material with high light transmittance, and the
diffuser sheet
114 may be further installed on the front substrate
110.
A front electrode
112 on the front substrate
110 discharges together
with two rear electrodes
122 on the rear substrate
120, which are
associated with the front electrode
112 and are located under the front
electrode
112. To be more specific, as shown by the two horizontal dashed
lines of FIG. 5, a tip electrode
112a at one side of the front electrode
112 stably discharges with a nearest portion at the rear electrode
122
where a tip electrode
122a is not formed, in order to form a stable
plasma discharge. A tip electrode
112a at the other side of the front
electrode
112 generates stable discharging together with a nearest portion
of a rear electrode
122 where a tip electrode
122a is not
formed. Hence, many fine charging operations are performed by the tip electrodes
112a and
122a. Consequently, current concentration
is prevented, discharging evenly occurs over the entire flat lamp, and brightness
of the lamp increases.
The reflective plate (not shown) increases the brightness by reflecting descending
light upward within the flat lamp
100.
In the first embodiment, tip electrodes are formed on both of the front and rear
electrodes. However, in a modified embodiment, while a tip electrode is formed
on a front electrode or a rear electrode, no tip electrodes are formed on a rear
electrode corresponding to the front electrode or a front electrode corresponding
to the rear electrode with a tip electrode. In the modified embodiment, a DC voltage
is applied. In order to achieve a highly-efficient, stabilized discharging of flat
lamps, preferably, a cathode is connected to the electrodes with tip electrodes,
and an anode is connected to the electrodes with no tip electrodes. In another
modified embodiment, tip electrodes are formed on neither the front electrodes
nor the rear electrodes. In this modified embodiment, preferably, an AC voltage
is applied to the front and rear electrodes as in the first embodiment of the present invention.
FIG. 6 is a partial cross-section of a flat lamp
200 with horizontal
facing electrodes according to a second embodiment of the present invention. FIG.
7 is a perspective plan view schematically showing the arrangement of the discharging
electrodes of FIG.
6. The same elements as those in the first embodiment
will not be described in detail.
Referring to FIGS. 6 and 7, a discharging space filled with a discharge
gas is formed between front and rear substrates
210 and
220 which
are isolated from each other by a wall
240. Electrodes
212 and
222
are formed in strips at predetermined intervals on the facing surfaces of the front
and rear substrates
210 and
220, respectively, in such a way that
the electrodes
212 alternate with the electrodes
222. Each of the
front electrodes
212 is composed of two unit electrodes
212a and
212b disposed side by side, and each of the rear electrodes
222
is composed of two unit electrodes
222a and
222b disposed
side by side. Each of the unit electrodes
212a,
212b,
222a, and
222b is protected by a dielectric layer
230.
A fluorescent layer
250 is formed on the inner surfaces of the front and
rear substrates
210 and
220 and on the inner surface of the wall
240.
The unit electrodes
212a and
212b, formed in strips,
have a plurality of tip electrodes
212c arranged at predetermined
intervals along their outer sides. Likewise, the unit electrodes
222a
and
222b, formed in strips, have a plurality of tip electrodes
222c arranged at predetermined intervals along their outer sides.
The tip electrodes
212c and
222c are arranged at the
front and rear electrodes
212 and
222, respectively, in such a way
that the tip electrodes
212c of a front electrode
212 alternate
with the tip electrodes
222c on an adjacent rear electrode
222.
When power is applied to the front and rear electrodes
212 and
222
of the flat lamp
200 having such a structure, either an electrode
212a
or
212b of a front electrode
212 discharge together with
the nearest unit electrode
222a or
222b of two rear
electrodes
222 which are associated with the front electrode
212.
To be more specific, a tip electrode
212c of the front electrode
212 performs stable plasma discharging together with a closest portion of
an adjacent rear electrode
222 where a tip electrode
222c is
not formed.
FIG. 8 is a partial cross-section of a flat lamp
300 with horizontal
facing electrodes according to a third embodiment of the present invention. FIG.
9 is a perspective plan view schematically showing the arrangement of the discharging
electrodes of FIG.
8. The same elements as those in the first and second
embodiments will not be described in detail.
Referring to FIGS. 8 and 9, a discharging space filled with a discharge
gas is formed between front and rear substrates
310 and
320 which
are isolated from each other by a wall
340. Electrodes
312 are formed
in strips at predetermined intervals on the inner surface of the front substrate
310, and electrodes
322, each of which is composed of two unit electrodes
322a and
322b, are formed in strips at predetermined
intervals on the inner surface of the rear substrate
320. The front electrodes
312 alternate with the rear electrodes
322. Each of the front and
rear electrodes
312 and
322 is protected by a dielectric layer
330.
A fluorescent layer
350 is formed on the inner surfaces of the front and
rear substrates
310 and
320 and on the inner surface of the wall
340.
The unit electrodes
322a and
322b, formed in strips,
have a plurality of tip electrodes
322c arranged along their outer
sides in such a way that the tip electrodes
322c of the unit electrode
322a alternate with those of the unit electrode
322b.
Also, the front electrodes
312, formed in strips, have a plurality of
tip electrodes
312c arranged on their both sides. The tip electrodes
312c and
322c are arranged on the front and rear electrodes
312 and
322, respectively, in such a way that the tip electrodes
312c of a front electrode
312 alternate with the tip electrodes
322c at an adjacent rear electrode
322.
When power is applied to the front and rear electrodes
312 and
322
of the flat lamp
300 having such a structure, a front electrode
312
discharges with the unit electrodes
322a and
322b of
two rear electrodes
322 which are associated with the front electrode
312.
To be more specific, a tip electrode
312c of the front electrode
312 performs stable plasma discharging together with a closest portion of
an adjacent rear electrode
322 where a tip electrode
322c is
not formed.
As described above, a flat lamp with horizontal facing electrodes according to
the present invention has discharging electrodes formed on two substrates in such
a way that the electrodes on one substrate alternate with the electrodes on the
other substrate. Accordingly, the discharging distance between front and rear electrodes
is lengthened, and many fine discharging operations occur between tip electrodes
extending from the lateral sides of the electrode strips and flat portions of corresponding
electrode strips. Therefore, current concentration is prevented, and thus uniform
discharging is achieved and brightness increases. Furthermore, stable discharging
is achieved, and thus a large brightness area can be selectively obtained.
While the present invention has been particularly shown and described with
reference to exemplary embodiments thereof, it will be understood by those of ordinary
skill in the art that various changes in form and details may be made therein without
departing from the spirit and scope of the present invention as defined by the
following claims.
*
