This application claims the benefit of Korean Patent Application No. 10-2005-0096231, filed on Oct. 12, 2005 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 embodiments relate to a plasma display panel (PDP), and more particularly, to a PDP comprising an accelerated electron emitter between sustain electrodes to effectively emit electrons in a discharge space so as to provide high brightness and high luminescence efficiency.
2. Description of the Related Art
Plasma display panels (PDPs) display images using visible light emitted through a process of exciting a phosphor material with ultraviolet rays generated from a discharge of a discharge gas between electrodes when a direct voltage or an alternating voltage is applied to the electrodes.
PDPs are classified into DC type panels and AC type panels according to discharge types. Also, PDPs are classified into facing discharge type panels and surface discharge type panels according to the arrangement of electrodes.
However, conventional PDPs generate ultraviolet rays by ionizing the discharge gas and allowing excited xenon (Xe*) to stabilize by performing a plasma discharge. Therefore, conventional PDPs have a high driving voltage and low luminescence efficiency since a large amount of energy is necessary to ionize the discharge gas.
According to one aspect of the present embodiments, there is provided a PDP comprising: first and second substrates separated by a predetermined distance and facing each other to form a discharge space therebetween; a plurality of barrier ribs interposed between the first and second substrates and partitioning the discharge space into discharge cells; a plurality of pairs of sustain electrodes; address electrodes crossing the plurality of pairs of sustain electrodes; electron emission members comprising electron emission amplification layers to amplify the emission of electrons in the discharge cells being formed, and corresponding to the plurality of pairs of sustain electrodes; phosphor layers formed in the discharge cells; and a discharge gas in the discharge cells.
The plurality of pairs of sustain electrodes may be parallel to one another and disposed in the barrier ribs.
The electron emission members may have the same width as the sustain electrodes, and the sustain electrodes may comprise bus electrodes, and the electron emission members may have the same width as the bus electrodes.
Another embodiment refers to a PDP comprising a first substrate and a second substrate spaced apart from each other with a discharge space therebetween; a plurality of barrier ribs interposed between the first and second substrates and partitioning the discharge space into a plurality of discharge cells; first discharge electrodes disposed on the first substrate; second discharge electrodes disposed on the second substrate and crossing the first electrodes; electron emission members comprising electron emission amplification layers to amplify the emission of electrons in discharge cells being formed corresponding to one of the first and second discharge electrodes; phosphor layers arranged in the discharge cells; and a discharge gas in the discharge cells.
The electron emission amplification layers may have any of the following characteristics: be oxidized porous silicon (OPS) layers, have a metal-insulator-metal (MIM) structure, be formed of a boron nitride bamboo shoot (BNBS), be formed of carbon nanotubes (CNTs), and further comprise emission electrodes disposed on the electron emission amplification layers.
The phosphor layers may include a quantum dot (QD).
The above and other features and advantages of the present embodiments will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:
The present embodiments will now be described more fully with reference to the accompanying drawings, in which exemplary embodiments are shown.
The first substrate 110 and the second substrate 120 are separated by a predetermined distance and face each other to form a discharge space. The second substrate 120 is formed of a transparent material such as glass to transmit visible light. However, the present embodiments are not limited thereto. For example, the first substrate 110 can be formed of a transparent material, or both the first substrate 110 and the second substrate 120 can be formed of a transparent material. Also, the first substrate 110 and the second substrate 120 can be formed of a translucent material and comprise a color filter. Therefore, the present embodiments can be applied to a backlit PDP or a reflective PDP in which visible light generated by projecting vacuum ultraviolet (VUV) rays from an excited discharge gas onto the phosphor layers 115 is reflected as well.
The barrier ribs 113 partitions the discharge space between the first substrate 110 and the second substrate 120 into discharge cells as basic units of an image, and prevents cross talk between discharge cells. The barrier ribs 113 can have rectangular cross-sections, but the present embodiments are not limited thereto. For example, the barrier ribs 113 can have cross-sections in the shape of ovals, circles, or polygons such as hexagons, octagons, etc.
The X and Y sustain electrodes 121 and 122 are parallel to one another on the bottom surface of the second substrate 120. The X electrodes 121 each include a transparent electrode 121 a and a bus electrode 121 b, and the Y electrodes 122 each include a transparent electrode 122a and a bus electrode 122b. The transparent electrodes 121a and 122a are formed of a transparent material such as indium tin oxide (ITO) to transmit visible light. However, ITO has high electrical resistance and causes a large voltage drop, and thus cannot itself apply a constant driving voltage to all discharge cells. Therefore, to supplement the transparent electrodes 121a and 122a, the bus electrodes 121b and 122b that have narrower widths and greater electrical conductivity than the transparent electrodes 121a and 122a are disposed on the transparent electrodes 121a and 122a and electrically connected to the transparent electrodes 121a and 122a, but the present embodiments are not limited thereto. In an embodiment, the PDP includes transparent electrodes not formed of ITO and excludes bus electrodes.
In the backlit PDP, the X and Y electrodes 121 and 122 are not transparent electrodes, and are formed of an opaque and electrically conductive material such as Cu, Al, or the like, however, there is no particular restriction to an electrode material in this case.
The first dielectric layer 112 covers the address electrodes 111 and is formed of a material having high resistance since it is used to insulate the address electrodes 111. The first dielectric layer 112 does not need to transmit visible light, and thus, does not need to be formed of a material having high light transmittance, whereas the second dielectric layer 123 transmits visible light. The second dielectric layer 123 covers the X and Y electrodes 121 and 122 disposed on the second substrate 120, and insulates the X and Y electrodes 121 and 122. Thus, the second dielectric layer 123 is formed of a material having high resistance and high light transmittance. The protective layer 124 covers the second dielectric layer 123 and discharges secondary electrons to facilitate the discharge.
The protective layer 124 is formed of magnesium oxide (MgO). The protective layer 124 covers the surface of the electron emission members 125 and the second dielectric layer 123 but the present embodiments are not limited thereto. In detail, the protective layer 124 can be disposed on a dielectric layer on which the electron emission members 125 are not formed, or on the electron emission members 125.
The phosphor layers 115 cover inner walls of discharge cells 114 partitioned by the barrier ribs 113 and the first dielectric layer 112, and provide photoluminescence (PL) by emitting visible light when electrons excited by absorbed VUV rays generated by the discharge are stabilized. The phosphor layers 115 include red, green, blue phosphor layers such that the PDP can display a color image. A combination of three adjacent discharge cells including the red, green, and blue phosphor layers constitute a unit pixel. The phosphor layers 115 can be formed of at least one of a PL phosphor layer that generates visible light when atoms receive energy in a region of ultraviolet rays and are stabilized, a cathodoluminescence (CL) phosphor layer, and a quantum dot (QD). The CL phosphor layer or the QD can be arranged in the discharge cells 114 when an electron beam is directly radiated from the electron emission members 125, and the PL phosphor layer can be arranged in the discharge cells 114 when an electronic beam is not directly radiated from the electron emission members 125.
In particular, there is no interference between atoms in the QD when the QD receives energy from the outside. Therefore, since the discharge gas can be excited using low energy, the PDP of the present embodiments can have increased luminescence efficiency, perform a printing process, and be large-sized.
Each of the electron emission members 125 comprises a base electrode 125a disposed on the bottom surface of the second dielectric layer 123 and an electron emission amplification layer 125b that is formed on the bottom surface of the base electrode 125a and has the same width as the base electrode 125a. The base electrodes 125a correspond to the X and Y electrodes 121 and 122, are formed on the bottom surface of the second dielectric layer 123, and can have the same width as the X and Y electrodes 121 and 122. For example, referring to
The base electrodes 125a serve as cathode electrodes and provide electrons to the electron emission amplification layers 125b. The base electrodes 124a can be formed of one of ITO, Al, Ag, etc. Referring to
The electron emission amplification layers 125b accelerate or amplify the electrons from the base electrodes 125a. The electron emission amplification layers 125b may be oxidized porous silicon (OPS) layers. OPS layers can be oxidized porous polysilicon (OPPS) layers or oxidized porous amorphous silicon (OPAS) layers. A method of forming an OPS layer includes applying a proper current density to a silicon layer and anodizing the silicon layer using a solution mixing hydrogen fluoride (HF) and ethanol to change the silicon layer into a porous layer. The anodized silicon layer is electrochemically oxidized and is changed into the OPS layer having a predetermined thickness.
The electron emission amplification layers 125b can have a metal-insulator-metal (MIM) structure. The MIM structure includes a thin insulating layer. The thickness of the insulating layer is relevant to increase electron emission efficiency of the electron emission members 125 having the MIM structure. The insulating layer can be formed of, for example, one of A12O3, Si3N4, SiO2, etc., and must be thin enough to allow tunneling. However, the insulating layers must be sufficiently thick not to break when voltages are applied to ends of the base electrodes 125a and emission electrodes.
The electron emission amplification layers 125b can be formed of a boron nitride bamboo shoot (BNBS). The BNBS has transparent properties over a wavelength range of from about 380 to about 780 nm, which is a visible light range, and good electron emission characteristics since it has negative electronic affinity. The BNBS formed in the sustain electrodes has very sharp ends, and thus it produces a strong electric field, thereby maintaining a sustain discharge at a low voltage.
The electron emission amplification layers 125b can be formed of carbon nanotubes (CNTs). However, the present embodiments are not limited thereto. The electron emission amplification layers 125b can be formed of a material that amplifies electron emission and generates an electron beam. The electron emission amplification layers 125b can be also formed of a material such as MgO for reducing the discharge voltage.
A discharge gas of a general PDP can be a mixture containing one or more of Ne gas, He gas, and Ar gas mixed with Xe gas. However, the electron beam emitted from the electron emission member 125 of the current embodiment excites a gas that in turn generates ultraviolet rays. That is, various gases including N2, deuterium, carbon dioxide, hydrogen gas, carbon monoxide, Kr, etc. and air at atmospheric pressure can be used instead of gases including Xe. Therefore, the PDPs according to some embodiments can use discharge gases used by general PDPs as well as other gases.
The function and operation of the PDPs will now be described. First, the PDPs perform an initial reset operation to produce wall charges in each of the discharge cells 114. When an operating voltage is applied between the X and Y electrodes 121 and 122 in a selected discharge cell, the discharge between the X and Y electrodes 121 and 122 is performed. When the discharge is performed, discharge gas particles of the discharge cells 114 and charges collide, thereby generating plasma. The phosphor layers 115, which cover the sidewalls and bottom surface of the barrier ribs 113, absorb VUV rays emitted when discharge gas atoms excited in the plasma are stabilized. The absorbed VUV rays excite electrons in the phosphor layers 115, and the excited electrons are stabilized, thereby emitting visible light. The emitted visible light from the discharge cells 114 transmit through the second substrate 120, thereby forming an image.
When an alternating current voltage (for example, ranging between 0 V and 200 V) is applied to the X electrodes 121 and the Y electrodes 122, an electric field is formed between a portion of a dielectric layer corresponding to the X electrodes 121 and a portion of the dielectric layer corresponding to the Y electrodes 122 in the discharge cells 114, such that electrons flow from the base electrodes 125a on the Y electrodes 122 to the electron emission amplification layers 125b and are accelerated or amplified to emit the electron beam into the discharge cells 114. If the voltage applied between the X and Y electrodes 121 and 122 is reversed, the electrons are accelerated or amplified through the electron emission member 125 on the X electrodes 121 to emit the electron beam into the discharge cells 114. The emitted electron beam excites the gas and the exited gas is stabilized to emit ultraviolet rays. The ultraviolet rays excite the phosphor layers 115 to emit visible light.
With regard to the PDP illustrated in
That is, in addition to the VUV rays generated when discharge gas atoms ionized by the plasma discharge are stabilized, the electron beams that are accelerated and emitted through the electron emission amplification layers 125 further excite the discharge gas, resulting in the generation of additional VUV rays. Also, the electron beams that are accelerated through the emission amplification layers 125 such as the OPS layers in the discharge cells to augment the discharge, thereby realizing high brightness and high luminescence efficiency. Although the PDPs illustrated in
Referring to
Referring to
Referring to
The sustain electrodes 221 and 222 disposed in the barrier ribs 213 surround the discharge cell 214 and cross the address electrode 211. Since the sustain electrodes 221 and 22 are disposed in the barrier ribs 213, common electrodes 221 and scan electrodes 222 constituting the sustain electrodes 221 and 222 are not transparent, and can be formed of a material including a conductive metal such as, for example, Ag, Al, Cu, etc. In
The electron emission members 225 and 226 respectively comprise base electrodes 225a and 226a that are disposed on the barrier ribs 213 and correspond to the sustain electrodes 221 and 222, and electron emission amplification layers 225b and 226b that are formed on the base electrodes 225a and 226a and have the same width as the base electrodes 225a and 226a. The base electrodes 225a and 226a serve as cathode electrodes providing electrons to the electron emission amplification layers 225b and 226b. The base electrodes 225a and 226a do not need to be formed of a transparent conductive material since they are not disposed on the first substrate 210 or the second substrate 220. As in the PDP illustrated in
Referring to
The function and operation of the PDPs illustrated in
The PDPs illustrated in
The PDPs illustrated in
The two pairs of sustain electrodes 321 and 322 are discharge electrodes in the form of strips and disposed in the barrier ribs 313, include common electrodes 321 and scan electrodes 322 that are spaced apart from each other, and cross the address electrode 311. The electron emission members 325 and 326 respectively comprise base electrodes 325a and 326a that are disposed on the barrier ribs 313 and correspond to the common electrodes 321 and the scan electrodes 322, and electron emission amplification layers 325b and 326b that are formed on the base electrodes 325a and 326a and have the same width as the base electrodes 325a and 326a. The base electrodes 325a and 326a serve as cathode electrodes providing electrons to the electron emission amplification layers 325b and 326b. The base electrodes 325a and 326a do not need to be formed of a transparent conductive material since they are not disposed on the first substrate 310 and the second substrate 320. As with the PDP illustrated in
In the embodiment illustrated in
The function and operation of the PDPs illustrated in
Therefore, electrons flow from the base electrode 325a adjacent to the common electrodes 321 to the electron emission amplification layer 325b and are accelerated or amplified to form the electron beam in the discharge cell 314. When the voltage between the sustain electrodes 321 and 322 is reversed, the electrons are accelerated or amplified by the electron emission members 325 adjacent to the scan electrodes 322 to emit the electron beam into the discharge cell 314. The emitted electron beam excites a gas and the exited gas stabilizes to emit ultraviolet rays. The ultraviolet rays excite the phosphor layers 315 to emit visible light.
The facing discharge PDP has sufficient space between the sustain electrodes 321 and 322, which facilitate the sustain discharge, and thus has high luminescence efficiency. However, the driving voltage for initiating the discharge is increased due to the wide space between the sustain electrodes 321 and 322. Since the electron beam is emitted through the electron emission members 325 and 326, the driving voltage for initiating the discharge is reduced and luminescence efficiency is increased. Other functions and operations of the PDPs illustrated in
The PDPs of
The first discharge electrode 411 is disposed on the upper surface of the first substrate 410. The second discharge electrode 421 is disposed on the bottom surface of the second substrate 420 and crosses the first discharge electrode 411. The first discharge electrode 411 and the second discharge electrode 421 serve as a scan electrode and an address electrode, respectively, or vice versa. The first discharge electrode 411 and the second discharge electrode 421 form strips, but the present embodiments are not limited thereto. That is, the first discharge electrode 411 and the second discharge electrode 421 can form various patterns, including a zigzag.
The electron emission members 425 and 426 respectively comprise base electrodes 425a and 426a that are disposed on the second discharge electrode 421 and the second dielectric layer 412 and correspond to the second discharge electrode 421 and the first discharge electrode 411, and electron emission amplification layers 425b and 426b that are formed on the base electrodes 425a and 426a and have the same width as the base electrodes 425a and 426a. The base electrodes 425a and 426a serve as cathode electrodes providing electrons to the electron emission amplification layers 425b and 426b. The base electrodes 425a and 426a may be formed of a transparent conductive material to transmit visible light. As with the PDP illustrated in
In the PDP illustrated in
The function and operation of the PDPs illustrated in
Therefore, electrons flow from the base electrode 426a on the first discharge electrode 411 (but only electron emitter 425 is above the first discharge electrode 411) to the electron emission amplification layers 425b and 426b and are accelerated or amplified to produce the electron beam in the discharge cell 414. When the voltage between the first and second discharge electrodes 411 and 421 is reversed, electrons are accelerated or amplified by the electron emission member 425 on the second discharge electrode 421 (but only electron emitter 425 is above the second discharge electrode 421) to form the electron beam in the discharge cell 414. Since the electron beam is emitted through the electron emission members 425 and 426, the driving voltage required to initiate the discharge is reduced and luminescence efficiency is increased. Other functions and operations of the PDPs illustrated in
The PDPs illustrated in
The first discharge electrode 511 is disposed on the upper surface of the first substrate 510. The second discharge electrode 521 is disposed on the bottom surface of the second substrate 520 and crosses the first discharge electrode 511. The first discharge electrode 511 and the second discharge electrode 521 are formed in strips, but the present embodiments are not limited thereto. That is, the first discharge electrode 511 and the second discharge electrode 521 can also have various patterns including a zigzag.
The electron emission member 526b comprises an electron emission amplification layer 526b that is formed on the first discharge electrode 511 and has the same width as the first discharge electrode 511. The first discharge electrode 511 contacts the electron emission member 526, is a base electrode 526a of the electron emission member 526, and serves as a cathode electrode. Therefore, a base electrode is not required. The electron emission amplification layer 526b is formed on the first discharge electrode 511 but the present embodiments are not limited thereto. For example, the electron emission amplification layer 526b can be formed on the second discharge electrode 521. In this case, the second discharge electrode 521 serves as the cathode electrode.
As in the PDP illustrated in
The function and operation of the PDPs illustrated in
In this regard, the discharge is performed directly between the first discharge electrode 511 and the second discharge electrode 512, causing the flow of a discharge current. To control the discharge operation, the discharge current must be properly controlled. In the PDP illustrated in
Since the electron beam is emitted through the electron emission members 526, a driving voltage for initiating the discharge is reduced and luminescence efficiency is increased. The DC 2D opposed discharge PDPs illustrated in
The flat lamp comprises upper and lower panels. The upper and lower panels face each other and form a discharge space therebetween. A plurality of spacers are interposed between the upper and bottom panels and partition the discharge space into a plurality of discharge cells. The discharge cells are filled with a discharge gas containing Ne, Xe, a mixture of He and Xe, a mixture of Ne, Ar and Xe or a mixture of He, Ne and Xe. Phosphor layers are formed on inner walls of the discharge cells. The bottom panel comprises a bottom substrate, and at least one discharge electrode disposed on the bottom substrate. The upper panel comprises an upper substrate, and at least one discharge electrode disposed on the upper substrate. The flat lamp further comprises a base electrode that is disposed on one of the upper and bottom panels and corresponds to the discharge electrode, and an electron emission member including an electron emission amplification layer formed on the base electrode. The electron emission member can further comprise an emission electrode on the electron emission amplification layer. The emission electrode can be formed of ITO or fine wire mesh. The electron emission amplification layer can be formed of a material that amplifies emitted electrons and generates an electronic beam such as an OPS, an MIM, a BNBS, a CNT, etc. A phosphor layer can be formed in any location of the discharge cell. As in the PDP illustrated in
In connection with the function and operation of the flat lamp, when a predetermined voltage is applied to the discharge electrode, electrons are amplified or accelerated in the electron emission amplification layer, and are emitted into the discharge cell, thereby increasing brightness and luminescence efficiency of the flat lamp.
The present embodiments provide a plasma display panel (PDP) with improved electronic emission characteristics due to the inclusion of an electronic emission member such as an oxidized porous silicon layer that reduces an operating voltage and increases luminescence efficiency.
While the present embodiments have 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 embodiments as defined by the following claims.
Number | Date | Country | Kind |
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10-2005-0096231 | Oct 2005 | KR | national |