U.S. patent application number 11/844189 was filed with the patent office on 2007-12-20 for electromagnetic interference shielding filter and manufacturing method thereof.
Invention is credited to Hong Rae Cha, Myeong Soo Chang, Kyung Ku Kim, Young Sung Kim, Byung Gil Ryu.
Application Number | 20070289774 11/844189 |
Document ID | / |
Family ID | 33411588 |
Filed Date | 2007-12-20 |
United States Patent
Application |
20070289774 |
Kind Code |
A1 |
Kim; Kyung Ku ; et
al. |
December 20, 2007 |
ELECTROMAGNETIC INTERFERENCE SHIELDING FILTER AND MANUFACTURING
METHOD THEREOF
Abstract
An electromagnetic interference (EMI) shielding filter includes
a conductive pattern for shielding electromagnetic waves; and
blackened layers formed on a surface of the conductive pattern. The
electromagnetic interference (EMI) shielding filter is manufactured
by preparing a base film; forming on the base film a first
blackened layer, a conductive layer, and a second blackened layer
in sequence; and patterning the first blackened layer, the
conductive layer, and the second blackened layer by using a same
mask, and forming on front and rear surfaces of an EMI shielding
layer a conductive pattern comprising the first and second
blackened layers.
Inventors: |
Kim; Kyung Ku; (Seoul,
KR) ; Cha; Hong Rae; (Seoul, KR) ; Kim; Young
Sung; (Yongin-si, KR) ; Chang; Myeong Soo;
(Woowang-si, KR) ; Ryu; Byung Gil; (Seoul,
KR) |
Correspondence
Address: |
LEE, HONG, DEGERMAN, KANG & SCHMADEKA
660 S. FIGUEROA STREET
Suite 2300
LOS ANGELES
CA
90017
US
|
Family ID: |
33411588 |
Appl. No.: |
11/844189 |
Filed: |
August 23, 2007 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11215478 |
Aug 29, 2005 |
|
|
|
11844189 |
Aug 23, 2007 |
|
|
|
10821304 |
Apr 9, 2004 |
|
|
|
11215478 |
Aug 29, 2005 |
|
|
|
Current U.S.
Class: |
174/350 |
Current CPC
Class: |
Y10T 29/49002 20150115;
Y10T 29/49117 20150115; H01J 11/44 20130101; H05K 9/0096 20130101;
H01J 11/12 20130101; H01J 2211/446 20130101 |
Class at
Publication: |
174/350 |
International
Class: |
H05K 9/00 20060101
H05K009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 10, 2003 |
KR |
10-2003-0022682 |
Claims
1. An electromagnetic interference (EMI) shielding filter,
comprising: a conductive pattern for shielding electromagnetic
waves; and blackened layers formed on a surface of the conductive
pattern.
2-13. (canceled)
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an electromagnetic
interference shielding filter and a manufacturing method thereof,
in which the surface of an electromagnetic interference shielding
layer is melanized (or blackened) to improve contrast ratio.
[0003] 2. Discussion of the Background Art
[0004] In general, image display devices have an electromagnetic
interference (EMI) shielding filter on the front surface to shield
emission of electromagnetic waves to outside. The EMI filters not
only shield electromagnetic waves but also transmit visible rays,
so they usually have a conductive mesh pattern. A related art
conductive mesh pattern, however, reflected an external light or a
visible ray from a display panel. As a result, contrast was
deteriorated. This problem is apparent in a plasma display panel
(hereinafter it is referred to as "PDP") that displays images by
using a gas discharge.
[0005] PDPs regulate gas discharge time of each pixel on the basis
of digital video data, and display an image. Typical examples of
these PDPs are AC PDPS, as shown in FIG. 1, which includes three
electrodes and are driven by an AC voltage.
[0006] FIG. 1 is a perspective view of a related art AC PDP. More
particularly, FIG. 1 illustrates the structure of a discharge cell
corresponding to a sub-pixel.
[0007] As shown in FIG. 1, the discharge cell is divided into an
upper plate 15 and a lower plate 25. The upper plate 15 includes an
upper substrate 10 where a sustain electrode pair 12A and 12B, an
upper dielectric layer 14, and a protective film 16 are formed in
sequence. The lower plate 25 includes a lower substrate 18 where an
address electrode 20, a lower dielectric layer 22, a barrier rib
24, and fluorescent layers 26.
[0008] The upper substrate 10 and the lower substrate 18 are spaced
out in parallel by the barrier rib 24. The sustain electrode pair
12A and 12B respectively includes a transparent electrode for
transmitting visible rays, and a metal electrode for compensating
resistance of the transparent electrode. The transparent electrode
is relatively wider than the metal electrode. The sustain electrode
pair 12A and 12B includes a scan electrode 12A and a sustain
electrode 12B. The scan electrode 12A provides scan signals for
determining data supply time, and sustain signals for sustaining
the gas discharge. On the other hand, the sustain electrode 12B
mainly provides sustain signals for sustaining the discharge. The
upper dielectric layer 14 and the lower dielectric layer 22 are
piled up with charges from the gas discharge. The protective film
16 protects the upper dielectric layer 14 from damages caused by a
sputtering of plasma and thus, extends lifespan of the PDP and
improves the emission efficiency of secondary electrons. The
protective film 16 is usually made from magnesium oxide NgO). The
dielectric layers 14 and 22 and the protective film 16 lower an
externally applied discharge voltage. The address electrode 20 is
formed at tight angles to the sustain electrode pair 12A and 12B.
The address electrode 20 provides data signals for selecting cells
to be displayed. The barrier rib 24 together with the upper and
lower substrates 10 and 18 create a discharge space. The barrier
rib 24 is formed in parallel with the address electrode 20, and
prevents ultraviolet rays generated by the gas discharge from being
leaked to the adjacent discharge cells. The fluorescent layer 26 is
applied to the surface of the lower dielectric layer 22 and barrier
rib 24, and generate one of visible rays in red, blue, or blue. The
discharge space is filled with different compositions of inert gas
mixtures including He, Ne, Ar, Xe, and Kr, or Excimer gas for
generating ultraviolet rays.
[0009] Thusly structured discharge cell is selected by an opposing
electrode discharge between the address electrode 20 and the scan
electrode 12A, and sustained by a surface discharge between the
scan electrode 12A and the sustain electrode 12B. Therefore, the
fluorescent layer 26 is excited by ultraviolet rays generated
during the sustain discharge, and visible rays are emitted to the
outside of the cell. In this case, the discharge cell controls the
cell's discharge sustain period, namely frequency of the sustain
discharge, according to video data, and emits a light at a gray
scale level.
[0010] FIG. 2 is a schematic perspective view of a PDP set
including the PDP 30 of FIG. 1.
[0011] As shown in FIG. 2, the PDP set includes a case 60, a
printed circuit board 50 (hereinafter, it is referred to as ("PCB")
housed in the case 60, a PDP 30, a glass type front filter 40, and
a cover 70 connected to the case 60 and encompassing the glass type
front filter 40.
[0012] As discussed before with reference to FIG. 1, the PDP 30
includes an upper plate 15 and a lower plate 25 connected to the
upper plate 15.
[0013] The PCB 50 disposed on the rear surface of the PDP 30
includes a plurality of driving and control circuits for driving
the sustain electrode pair 12A and 12B and the address electrode 20
formed on the PDP 30. Situate between the PCB 50 and the PDP 30 is
a heat radiation plate (not shown) for radiating heat emitted from
the PDP 30 and the PCB 50.
[0014] The glass type front filter 40 shields electromagnetic waves
generated from the PDP 30 towards the front surface, prevents
external light reflection, blocks near-infrared rays, and corrects
colors. To this end, the glass type front filter 40 includes, as
shown in FIG. 3, a first antireflection coating 44 attached to a
front surface of a glass substrate 42, an EMI shielding filter 46,
a NIR (near infrared ray) blocking film 48, a color correcting film
52, and a second antireflection coating 54, the EMI shielding film
46, the NIR blocking film 48, the color correcting film 52 and the
second antireflection coating 54 being layered in cited order on
the rear surface of the glass substrate 42.
[0015] The glass substrate 42 is made from a reinforced glass to
support the glass type front filter 40 and to protect the front
filter 42 and the PDP 30 from damages caused by external impacts.
The first and second antireflection coatings 44 and 54 prevent
incident light rays from outside from being reflected back to the
outside and thus, improve contrast effects. The EMI shielding
filter 46 absorbs electromagnetic waves generated from the PDP 30,
and shields the emission of the electromagnetic waves to outside.
The NIR blocking film 48 absorbs near infrared rays at a wavelength
band of 800-1000 nm that are generated from the PDP 30, and blocks
the emission of the near infrared rays to outside. This is how
infrared rays (approximately 947 nm) generated from a remote
controller are normally input to an infrared ray receiver built in
the PDP set. The color correcting film 52 contains a color dye,
which is used to adjust or correct colors, whereby color purity can
be improved. These films 44, 46, 48, 52, and 54 are adhered to the
glass substrate 42 through an adhesive or glue.
[0016] The case 60 protects the PCB 50, the glass type front filter
40 and the PDP 30 from external shocks, and shields electromagnetic
waves emitted from side and rear surfaces of the PDP 30. Also, to
ensure that the glass type front filter 40 is separated from the
PDP 30, the case 60 is electrically connected to the EMI shielding
filter 46 of the glass type front filter 40 through a support
member (not shown) that supports from the rear surface of the case
60. Therefore, the case 60 and the EMI shielding filter 46 of the
glass type front filter 40 are both earthed to a ground voltage,
and absorb electromagnetic waves emitted from the PDP 30 and
discharge them. This is how the emission of the electromagnetic
waves to outside is blocked.
[0017] Lastly, the cover 70 encompasses the outside of the glass
type front filter 40, and is connected to the case 60.
[0018] As discussed above, the related art PDP set includes the
glass type front filter 40 for shielding electromagnetic waves and
correcting optical characteristics. However, because the glass type
front filter 40 includes a glass substrate made from the reinforced
glass, which is relatively thick, the thickness and weight of the
PDP set were increased, and the cost of manufacture was also
increased.
[0019] As an attempt to solve the above-described problems, a film
type front filter without a glass substrate, as shown in FIG. 4,
has been suggested. The film type front filter 65 shown in FIG. 4
includes a color correcting film 68, a NIR blocking film 66, an EMI
shielding filter 64, and an antireflection layer 62, each being
sequentially adhered to an upper plate 15 of the PDP 30.
[0020] The antireflection coating 62 prevents incident light rays
from outside from being reflected back to the outside. The EMI
shielding filter 64 absorbs electromagnetic waves generated from
the PDP 30, and shields the emission of the electromagnetic waves
to outside. The NIR blocking film 66 absorbs near infrared rays
that are generated from the PDP 30, and blocks the emission of the
near infrared rays to outside. The color correcting film 68
contains a color dye, which is used to adjust or correct colors,
whereby color purity can be improved. These films 62, 64, 66, and
68 are adhered to the PDP 30 through an adhesive or glue.
[0021] Both the glass type front filter 40 of FIG. 3 and the film
type front filter 65 include an EMI shielding filter 46 or 64 for
shielding EMI from the PDP 30. As shown in FIGS. 5 and 6, the EMI
filter 46 or 64 includes an EMI shielding layer 75 formed of
conductive meshes 74 and frames 72 for supporting the conductive
meshes 74, and a base film 75 formed on the EMI shielding layer
75.
[0022] Referring to FIGS. 5 and 6, to form the conductive meshes 74
and the frames 72 a metal layer made from silver (Ag) or copper
(Cu) for example undergoes photolithography and etching processes
to be patterned. To be more specific, a metal foil is formed on the
base film 76, and the metal foil is coated with a photoresist.
Later, the photoresist coating is patterned by using a mask and
thus, the frame and a photoresist pattern in mesh type are formed.
The metal foil is patterned by using the photoresist pattern as a
mask, and as a result, the EMI shielding layer 75 including the
frames 72 and the conductive meshes 74 is formed on the base film
76, as illustrated in FIG. 6. Any photoresist patterns remaining on
the frames 72 and the conductive meshes 74 are removed through a
strip process.
[0023] The EMI shielding layer 75, namely the conductive meshes 74
and the frames 72, of the related art EMI shielding filter 46 or 64
is usually made from highly lustrous metals. Thus, an externally
incident lights R1 or display lights R2 emitted from the PDP 30 are
reflected by the metallic conductive meshes 74 and frames 72. These
reflected lights by the EMI shielding filter 75 increases overall
black level or brightness of the PDP 30, resulting in deterioration
of contrast ratio.
SUMMARY OF THE INVENTION
[0024] An object of the invention is to solve at least the above
problems and/or disadvantages and to provide at least the
advantages described hereinafter.
[0025] Accordingly, one object of the present invention is to solve
the foregoing problems by providing an electromagnetic interference
shielding filter and a manufacturing method thereof, in which the
surface of an electromagnetic interference shielding layer is
melanized (or blackened) to improve contrast ratio.
[0026] The foregoing and other objects and advantages are realized
by providing an electromagnetic interference (EMI) shielding
filter, including: a conductive pattern for shielding
electromagnetic waves; and blackened layers formed on a surface of
the conductive pattern.
[0027] Another aspect of the invention provides a manufacturing
method of an electromagnetic interference (EMI) shielding filter,
the method including the steps of preparing a base film; forming on
the base film a first blackened layer, a conductive layer, and a
second blackened layer in sequence; and patterning the first
blackened layer, the conductive layer, and the second blackened
layer by using a same mask, and forming on front and rear surfaces
of an EMI shielding layer a conductive pattern comprising the first
and second blackened layers.
[0028] Still another aspect of the invention provides a
manufacturing method of an electromagnetic interference (EMI)
shielding filter, the method including the steps of: preparing a
base film; forming on the base film a first blackened layer and a
conductive layer; patterning the first blackened layer and the
conductive layer by using a same mask, and forming on the rear
surface of an EMI shielding layer a conductive pattern comprising
the first blackened layer; and forming a second, third, and fourth
blackened layer for encompassing a front surface and both side
surfaces of the conductive pattern.
[0029] Another aspect of the invention provides a front filter of a
plasma display panel, in which the front filter includes a
conductive pattern for shielding electromagnetic waves, and a base
film for supporting the conductive pattern, and blacked layers are
formed on a part of the conductive pattern.
[0030] Additional advantages, objects, and features of the
invention will be set forth in part in the description which
follows and in part will become apparent to those having ordinary
skill in the art upon examination of the following or may be
learned from practice of the invention. The objects and advantages
of the invention may be realized and attained as particularly
pointed out in the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] The invention will be described in detail with reference to
the following drawings in which like reference numerals refer to
like elements wherein:
[0032] FIG. 1 is a perspective view of a related art
three-electrode AC surface discharge plasma display panel
(PDP);
[0033] FIG. 2 is a schematic perspective view of a PDP set
including a PDP of FIG. 1;
[0034] FIG. 3 is a cross-sectional view showing a vertical
structure of a glass type front filter and PDP of FIG. 2,
respectively;
[0035] FIG. 4 is a cross-sectional view showing a vertical
structure of a PDP to which a related art film type front filter is
attached;
[0036] FIG. 5 is a plan view showing a detailed structure of a
related art electromagnetic interference (EMI) shielding filter of
FIG. 3 and FIG. 4;
[0037] FIG. 6 is a cross-sectional view of a related art EMI
shielding filter, taken along line A-A' in FIG. 5;
[0038] FIG. 7 is a cross-sectional view showing a structure of an
EMI shielding filter according to a first embodiment of the present
invention,
[0039] FIGS. 8A and 8B are cross-sectional views showing a
step-by-step procedure for manufacturing an EMI shielding filter
according to the present invention;
[0040] FIG. 9 is a cross-sectional view showing a structure of an
EMI shielding filter according to a second embodiment of the
present invention; and
[0041] FIGS. 10A through 10C are cross-sectional views showing a
step-by-step procedure for manufacturing an EMI shielding filter
according to the present invention.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0042] The following detailed description will present an
electromagnetic interference (EMI) shielding filter and a
manufacturing method thereof according to a preferred embodiment of
the invention in reference to the accompanying drawings.
[0043] FIG. 7 is a cross-sectional view showing a structure of an
EMI shielding filter according to a first embodiment of the present
invention. As shown in FIG. 7, the EMI shielding filter includes an
EMI shielding layer 83 formed of conductive meshes 84 and frames 86
for supporting the conductive meshes 84, and a base film 82 on
which the EMI shielding layer 83 is formed.
[0044] The conductive meshes 84 of the EMI shielding layer 83 are
positioned at an area where light (visible rays) from a display
panel (e.g., a PDP) is transmitted, and secure transmittance and
absorb electromagnetic waves emitted from the display panel. The
frames 86 encompasses outside of the conductive meshes 84 to
support the conductive meshes 84 and to form a discharge path for
absorbed electromagnetic waves. The EMI shielding layer 83 formed
of the conductive meshes 84 and the frames 86 are made from metals
including silver (Ag) or copper (Cu).
[0045] The base film 82 supports the EMI shielding layer 83.
[0046] Also, a blackened layer 88 is formed on the surface of the
metallic EMI shielding layer 83 to prevent light reflection. More
specifically, the blackened layer 88 includes a first blackened
layer 88A formed on a rear surface of the EMI shielding layer 83 to
absorb a display light from the display panel, and a second
blackened layer 88B formed on a front surface of the EMI shielding
layer 83 to absorb an externally incident light. Therefore, the
blackened layer 88 is useful for preventing the external light
reflection and display light reflection by the EMI shielding layer
83, and as a result thereof, contrast ratio can be improved.
[0047] Here, the blackened layer 88 can be formed by oxidizing
metals like Cu or Ni or oxidizing an alloy.
[0048] In addition, at least one of the first and second blackened
layers 88A and 88B can be formed by oxidizing the EMI shielding
layer 83.
[0049] A manufacturing method of the EMI shielding filter with the
above structure will be now explained.
[0050] As shown in FIG. 8A, a base film 82 is first prepared, and
then the first blackened layer 88A, a conductive layer 85 and the
second blackened layer 88B are sequentially formed on the top of
the base film 82. Here, the conductive layer 85 is formed trough a
deposition process like a sputtering. The first and second
blackened layers 88A and 88B are formed through a screen printing,
compound thin film coating, or electrochemical blackening
process.
[0051] The second blackened layer 88B is coated with a
photo-resist, and the photoresist is patterned through a mask. In
this manner, a photoresist pattern is formed on the frames and
meshes. Using the photoresist pattern as a mask, the second
blackened layer 88B, the conductive layer 85, and the first
blackened layer 88A are patterned in like manner. Hence, as shown
in FIG. 8B, the first and second blackened layers 88A and 88B are
formed on the rear and front surfaces of the EMI shielding layer,
that is on the rear and front surfaces of the conductive meshes 84
and frames 86, respectively. Lastly, any photoresist patterns
remaining on the second blackened layer 88B are removed through a
strip process.
[0052] FIG. 9 is a cross-sectional view showing a structure of an
EMI shielding filter according to a second embodiment of the
present invention. As shown in FIG. 9, the EMI shielding filter
includes an EMI shielding layer 93 formed of conductive meshes 94
and frames 96 for supporting the conductive meshes 94, and a base
film 92 on which the EMI shielding layer 83 is formed.
[0053] The conductive meshes 94 of the EMI shielding layer 93 are
positioned at an area where light (visible rays) from a display
panel (e.g., a PDP) is transmitted, and secure transmittance and
absorb electromagnetic waves emitted from the display panel. The
frames 96 encompasses outside of the conductive meshes 94 to
support the conductive meshes 94 and to form a discharge path for
absorbed electromagnetic waves. The EMI shielding layer 93 formed
of the conductive meshes 94 and the frames 96 are made from metals
including silver (Ag) or copper (Cu).
[0054] The base film 92 supports the EMI shielding layer 93.
[0055] Also, a blackened layer 98 is formed on the surface of the
metallic EMI shielding layer 93 to prevent light reflection. More
specifically, the blackened layer 98 includes first through fourth
blackened layers 98A through 98D that are formed on the front, rear
and both side surfaces of the EMI shielding layer 93, respectively.
The second blackened layer 98B formed on the front surface of the
EMI shielding layer 93 absorbs an externally incident light, the
first blackened layer 98A formed on the rear surface of the EMI
shielding layer 93 absorbs a display light from the display panel,
and the third and fourth blackened layers 98C and 98D formed on
both sides of the EMI shielding layer 93 absorb the external light
and the display light, respectively. Therefore, the blackened layer
98 is useful for preventing the external light reflection and
display light reflection by the EMI shielding layer 93, and as a
result thereof, contrast ratio can be improved.
[0056] A manufacturing method of the EMI shielding filter with the
above structure will be now explained.
[0057] As shown in FIG. 10A, a base film 92 is first prepared, and
then the first blackened layer 98A, and a conductive layer 95 are
sequentially formed on the top of the base film 92. Here, the
conductive layer 95 is formed through a deposition process like a
sputtering. The first blackened layers 88A is formed through a
screen printing or compound thin film coating process.
[0058] The conductive layer 95 is coated with a photoresist, and
the photoresist is patterned through a mask. In this manner, a
photoresist pattern is formed on the frames and meshes. Using the
photoresist pattern as a mask, the conductive layer 95 and the
first blackened layer 98A ate patterned in like manner. Hence, as
shown in FIG. 10B, the EMI shielding layer, that is, the conductive
meshes 94 and frames 96, is formed on the base film 92, and the
first blackened layer 98A is formed on the rear surfaces of the
conductive meshes 94 and frames 96, respectively. Any photoresist
patterns remaining on the conductive meshes 94 and frames 96 are
removed through a strip process.
[0059] Referring to FIG. 10C, after the first blackened layer 98A
is formed, the second through fourth blackened layers 98B through
98D are formed on the surface of the EMI shielding layer 93 formed
of the conductive meshes 94 and frames 96. The second through
fourth blackened layers 98B through 98D can be formed on the front
and both side surfaces of the conductive meshes 94 and frames 96
through an electrochemical blackening, e.g., electroless plating,
or screen printing or compound thin film coating process.
[0060] In conclusion, the EMI shielding filter and manufacturing
method thereof can be advantageously used for preventing external
light reflection and display light reflection by blackening the
surface of the EMI shielding filter and thus, can improve contrast
ratio of the display device.
[0061] While the invention has been shown and described with
reference to certain preferred embodiments thereof, it will be
understood by those skilled in the art that various changes in form
and details may be made therein without departing from the spirit
and scope of the invention as defined by the appended claims.
[0062] The foregoing embodiments and advantages are merely
exemplary and are not to be construed as limiting the present
invention. The present teaching can be readily applied to other
types of apparatuses. The description of the present invention is
intended to be illustrative, and not to limit the scope of the
claims. Many alternatives, modifications, and variations will be
apparent to those skilled in the art. In the claims,
means-plus-function clauses are intended to cover the structures
described herein as performing the recited function and not only
structural equivalents but also equivalent structures.
* * * * *