Patent for “Diode structure flat panel display”

Nanotechnology – Nalin Kumar, Chenggang Xie, Applied Nanotech Holdings Inc

Search Patent for “Diode structure flat panel display”

Abstract for “Diode structure flat panel display”

A matrix-addressed diode flatpanel display of field emission type is described. It uses a diode (two terminals) pixel structure. Flat panel displays consist of a cathode with a plurality cathodes. Each cathode includes a layer cathode-conductive material and another layer of low-effective work-function material. An anode has a plurality anodes. The anode is located near the cathode to receive charged particle emission from the cathode. The cathodoluminescent materials emits light in response to these charged particle emissions. Flat panel displays can be controlled to vary the field emission between the plurality light-emitting and field-emission anodes. This allows for an addressable grey scale operation.

Background for “Diode structure flat panel display”

CRTs (conventional cathode-ray tubes) are used in television sets and display monitors to display information. A luminescent phosphor coating is applied to a transparent surface, such as glass. This allows the CRT’s ability to communicate quality such as brightness, contrast, resolution, and color. Together, these qualities form a picture that can be viewed by a viewer.

Conventional CRTs, among other disadvantages, require significant physical depth (i.e. These units are heavy and cumbersome because they require a lot of space beyond the actual display screen. This physical depth can be detrimental for a variety of applications. The depth of many portable computer displays is too small to use conventional CRTs. Portable computers are unable to withstand the extra weight and power consumption associated with conventional CRTs. Displays have been created that are lighter, more compact, and consume less power than conventional CRTs to overcome these problems. These flat panel displays can be used with technologies such as active or passive matrix liquid crystal displays (‘LCD”), electroluminescent displays (‘EL”), or gas plasma displays.

A flat panel display fills in the gap left by CRTs. Flat panel displays that are based on liquid crystal technology produce pictures with low fidelity and/or non-emissive. Although some liquid crystal displays can overcome the problem of non-emissiveness by using a backlight, this comes with its own drawback: it consumes more energy. This is a major disadvantage because portable computers are often powered by very limited batteries. Although passive matrix LCD can be made to perform better, active matrix LCD technology is not as efficient due to the complex manufacturing processes and tight tolerances. While EL and gas plasma display are brighter than liquid crystal displays and easier to read, they are also more costly and consume more energy.

Field emission displays combine the visual benefits of the CRT with the depth and weight, as well as the power consumption, of flat panel liquid crystal, gas plasma, and EL displays. These field emission displays employ very sharp micro-tips of silicon, molybdenum, and tungsten as the cold electron emitter. The presence of an electrical field between the cathode’s grid and the cathode generates light by generating electrons.

U.S. Patent. No. No. 5,015,912, issued to Spindt and al. on May 14, 1991. It uses micro-tip cathodes that emit field energy type. The cathodes are integrated into the display backing structure and activate the corresponding cathodoluminescent zones on a faceplate. In the preferred embodiment, the face plate is placed 40 microns away from the cathode arrangement. A vacuum is also provided between the plate (and cathodes) in this space. The spacing is maintained by spacers that look like legs interspersed between the pixels. Electrical connections to the bases of the cathodes can be diffused through the backing structure.

Spindt and al. It provides its matrix-addressing scheme entirely within its cathode assembly. Each cathode has a number of electron emitting tips that project upwardly towards the face structure. To control and generate electron emission from the tips, an electrically conductive gate is placed adjacent to them. This arrangement is perpendicular the base stripes and contains apertures through the which electrons may be emitted from the tips. To produce emission from selected cathodes, the extraction electrode must be used in conjunction with the individual cathodes. In micro-tip cathodes made of silicon, molybdenum, or tungsten, the grid-cathode arrangement must be used. This is because the extraction field required to cause electron emission exceeds 50 Megavolts per mile (“MV/m ). The grid must be within 1 micrometer of the micro-tip cathodes. This tight tolerance requires that gate electrodes are produced using optical lithographic techniques on an electric insulating layer. This electrically separates each pixel’s gates from the common base. This type of photolithography can be expensive and time-consuming. It also results in higher rejection rates for finished displays.

Spindt and colleagues have identified two main problems with the device. 1) Formation of micro-tip cathodes; 2) Formation and alignment of extraction electrodes relative to the cathodes. Spindt and colleagues have described the structure. It is difficult to construct large-area displays because of its complexity. Spindt and co. However, it does not address the need to make a flat panel display that is simpler and more affordable to produce.

If the grid structure is not required and the micro-tips do not need to be sharp, these problems can be solved. You can use a flat cathode to emit electrons in a diode configuration, where the anode has been coated with aphosphor. This display is easy to build because it doesn’t require an extraction grid.

“Unfortunately, field emission flat panel displays with a diode (cathode/anode configuration) suffer from several disadvantages.”

The voltage between the cathode’s phosphors and the anode’s anode determines the energy of electrons that bombard phosphors. Color displays require that the cathode/anode voltage be greater than 300 volts. This is because the phosphors need to be excited by a high electron energy. The high voltage requirements make it more difficult for cathode/anode drivers to handle higher voltages, which makes them more expensive to produce. High voltage drivers can also be slow because it takes time to create the higher voltage on the conductors in the display.

Fowler-Nordheim theory (F-N) states that the current density of field emission changes by up to 10 percent when cathode/anode separators change by just 1 percent. Flat panel displays of the past have not been able to overcome field emission variations.

Flat panel displays must use an addressing scheme to place any information sent to them by a computer or another device in the correct order. Addressing simply refers to the way individual display elements or picture elements are accessed and set up to display the information.

Proper spacing between cathode and anode assemblies is another important issue in flat panel displays. Proper spacing is crucial in controlling field emission variation between pixel and minimizing the required voltage to drive the display. To maintain proper separation in triode displays, glass balls and fibers, as well as polyimides, polyimides, and other insulators, have been used. Because the electron extraction grid’s electric field is less than the one between the anode, electron extraction grid, and cathode (the electric field), separation is not as important. A spacer for diode displays must have a breakdown field that is greater than the electron extraction field of the cathode.

Flat panel displays are essential for today’s computer and video market. They must be capable of creating greys (halftones) images, which allows them to create graphic images as well as textual images. To implement grey-scale operation on a flat panel display, analog and duty cycle modulation techniques were used in the past.

“Analog control is the first. Individual pixels can be excited by varying voltage continuously, which allows grey-scale operation. Duty-cycle modulation is the second. The most popular version of this control is pulse-width modulation. In this case, a pixel is switched rapidly between the two states. If dwell times are not equal, the state can be altered to appear to be in any of a variety of grey states, including black or white. These two methods can be used to control diode displays.

To overcome these disadvantages, a matrix-addressable flat-panel display that is easy to make and inexpensive to maintain and has redundancy to allow for the continued operation of each pixel is needed. A sophisticated cathode/anode spacing system should be used to make the display reliable and affordable. The display should include a method of implementing a greyscale mode in a flat panel display with diode pixels structure. This allows individual pixels to assume shades of black or white and increases information-carrying capability and versatility.

The present invention is a flat panel display that uses the advantages of a cathodoluminescent-phosphor similar to the one used in CRTs. It also maintains a thin display. Flat panel displays are field emission types with diode (two terminals) pixel structures. The matrix-addressable display uses anode or cathode assemblies that are arranged in strips in a perpendicular relation. Each anode strip is individually addressable using cathode drivers. Each crossing of an anode and cathode strips results in a pixel. To maintain their addressability, both the anode and cathode strip are separated from each other. This allows each pixel to be illuminated individually.

“The cathode assembly may be either a flat cathode or a set of micro-tips which may be randomly patterned or photo-lithographically patterned. Flat cathodes are made up of a conductive layer that is deposited on top of a substrate, and a resistive layer that is deposited on top. The resistive layer is then covered with a thin film with a low effective work function. The preferred embodiment of this invention’s thin film is an amorphic diamond. You can further subdivide the cathode strips to permit operation at a specific pixel site, even if one of the divisions fails. The resistive layer is made of high-resistivity materials such as diamond or other similar materials and provides sufficient isolation between the different subdivisions. This multiple subdivisions of one pixel can be applied to either the cathode or anode.

The anode assembly is composed of transparent conductive materials such as indium-tinoxide (ITO), which are deposited on top of a substrate with low energy phosphors such as zinc oxide, ZnO.

The anode and cathode assemblies are then assembled using a peripheral glass frit seal on a printed circuit board. Spacers made of glass fibers, glass balls, or a fixed spacer using typical deposition technology ensure that the proper spacing between the assemblies. The preferred embodiment of this invention provides spacing by placing a number of spacers within holes in the cathode substrate to create a long surface path that will prevent current leakage from the cathode into the anode. An exhaust tube removes gases from the cathode assembly to create a vacuum. These structures have well-known systems for maintaining vacuums. A getter is used to eliminate any impurities in the vacuum.

Flexible connectors are used to make individual rows and columns of cathode and anode strips externally accessible. They are typically made from semiconductor packaging technology. These connectors can be attached to cathode and anode drivers to ensure that each pixel is addressable.

An individual pixel is lit when the potential between the anode strip and cathode is sufficient to emit electrons. These electrons then travel to the low-energy phosphor material. This type of electron emission requires a significant amount of voltage. Additional circuitry is required to switch this high voltage. Therefore, the constant potential between cathode and anode assemblies does not provide enough voltage to allow electron emission. Each anode or cathode strip is equipped with voltage drivers that provide the voltage necessary to enable electron emission. These voltage drivers are also known as cathode and anode drivers.

A pixel is addressed when the required driver voltage applied to the corresponding cathode and anode strips results in the emission of electrons from the portion of the cathode that is adjacent to the anode. Because the threshold potential between anode/cathode is not reached, electrons cannot be emitted from a pixel.

The present invention allows for grey-scale display by either providing a variable voltage to individual pixels or modulating a constant voltage (as is pulse-width modulation). Each anode strip can be subdivided into strips of different widths that are individually addressable using the anode drivers. The individual strips can be combined to activate different amounts of light emitting Phosphor material within a pixel using emitted electrons from their respective cathodes.

The present invention has many advantages, including low power consumption, high brightness and low drive voltage. The cathode assembly according to the present invention is simpler and cheaper to make than micro-tip-based triode displays. This is because sophisticated photolithography isn’t required to create a flat cathode arrangement.

Accordingly, the primary object of the invention is to provide a flat panel LCD display that includes 1) a cathode with a plurality cathodes and 2) an anode having a plurality anodes. Each anode has a layer cathode-conductive material and a lower effective work-function material. The anode assembly is located near the cathode to receive the cathode’s charged particle emissions. The cathodoluminescent materials emitting light.

“Another object in the present invention is to provide an electronic display wherein a plurality cathodes have relatively flat emission surfaces comprising a low-effective work-function material that has been arranged to form a plurality micro-crystallites.”

“A further object in the present invention is to provide an array of cathodes with micro-tipped emission surface.”

“A further object of this invention is to provide a display in which a plurality cathodes can be randomly manufactured.”

“Yet another object of the present invention is to provide a display wherein a plurality of cathodes are photolithographically fabricated.”

“Another object in the present invention” is to provide a display in which micro-crystallites act as emission sites.

“Another object of the present invention” is to make a display in which a low-effective work-function material, such as amorphic diamond films, is used.

“And another object is the present invention to provide a display in which emission sites contain dopant Atoms.”

“Another object of the present invention” is to display a dopant carbon atom.

“Yet another object of the present invention, however, is to provide a display in which emission sites have a distinct bonding structure than surrounding non-emission sites.”

“Yet another object of this invention is to provide an example where emission sites have a different bonding pattern from non-emission sites.”

“Another object of the present invention” is to provide a display in which emission sites contain dopants from an element other than a low-effective work-function material.

“And yet another object of this invention is to provide a display in which emission sites have defects in the crystalline structure.”

“Yet another object in the present invention is to provide an interface where defects are not point defects.”

“Yet another object of the present invention, is to provide a display in which defects are only line defects.”

“A further object of this invention is to provide a display in which defects are dislocations.”

“Another primary purpose of the present invention” is to provide a flat-panel display consisting of 1) a plurality corresponding light emitting anodes as well as field-emission cthodes, each anode emitting light in response electron emission from the respective cathodes; and 2) means for selectively changing field emission between the plurality corresponding anodes or field-emission cthodes to effect an addressable grey scale operation of the flat-panel display.

“Another object of the present invention” is to provide a display in which emission between a plurality corresponding light emitting anodes or field-emission canodes is varied through the application of a variable electric potential between selectable one of the plurality corresponding light emitting anodes or field-emission canodes.

“Another object in the present invention is to provide an electronic display wherein emission between a plurality corresponding light emitting anodes or field-emission cthodes can be varied by switching a constant electrical potential between selectable one of the plurality corresponding light emitting anodes or field-emission cthodes.”

“Another object of the present invention” is to provide a flat-panel display in which a constant electrical potential can be pulse width modulated to provide an addressable gray-scale operation.

The flat panel display of the invention also has the primary objective of 1) providing a plurality light-emitting and/or dark-emitting anodes that are excited by electrons emitted from one of a plurality field-emission cathodes, and 2) a circuit to electrically excite a specific cathode or anode pair by altering the electrical potential of each of them.”

“Another object of the present invention” is to provide a display in which the plurality of cathodes are divided into cathode subdivisions.

“Another object in the present invention is to provide an anode display that divides the plurality into anode subdivisions.”

“Another object of the present invention” is to display each cathode subdivision separately addressable.

“Another object of the present invention” is to display each anode subdivision separately addressable.

“Another object of the present invention” is to provide a display in which the cathode subdivisions can be addressed in different combinations, allowing grey scale operation of cathodes.

“Another object of the present invention” is to provide a display in which the anode subdivisions can be addressed in different combinations, allowing grey scale operation of anodes.

“Another object in the present invention is to provide an LCD display where the cathode subdivisions can be of different sizes.”

“Another object of the present invention” is to display anode subdivisions of different sizes.

“Another object of the present invention” is to display cathode subdivision sizes in a way that powers of 2 relate them.

“Another object of the present invention” is to display anode subdivision sizes in a way that powers of 2 relate to each other.

“Another object of the present invention” is to provide a display in which the plurality anodes are made up of phosphor strips.

“Another object in the present invention is to provide an LCD display wherein each plurality of cathodes includes:

“a substrate;”

“An electrically resistive layer that is deposited on top of the substrate; and

“A layer of material with a low effective function that is deposited on top of the resistive layer.”

“Another object of the present invention” is to provide a display in which the plurality and cathodes can be continuously separated by an electrical potential that is provided by a diode biasing system.

“Another object of the present invention” is to provide a display in which a particular corresponding anode and cathode pair activates when a total electric potential equals the sum of the electrical pot provided by the diode biasing and driver circuits.

“Another object of the present invention” is to provide a display in which the electrical potential provided through the driver circuit is substantially lower than that provided by diode biasing.

The preferred embodiment of this invention is a system to implement a grey scale on a flat panel display. It comprises: 1) a plurality field emission cathodes arranged horizontally, 2) a plurality light emitting anodes arranged vertically, each column sub-divided into columns, which are responsive to electrons from the cathodes. 3) a circuit to join the columns of cathodes and rows of cathodes to create a pattern of pixels, and 4) A circuit to address a combination of anode column, and for separately and simultaneously to produce different levels of pixel intensity.

“The above has provided a broad overview of the technical features and advantages of the present invention so that you can better understand the detailed description of this invention. The claims of the invention contain additional features and benefits. These will be described in detail here. The inventive concept and its specific embodiment can be used to modify or design other structures. This is a benefit that should be recognized by all who are skilled in the art. Those skilled in the art should realize that similar constructions to the invention do not violate the spirit or scope of the invention, as defined in the appended claims.

Referring to FIG. “Referring to FIG. 1, is a schematic of an exemplary system 100 for implementing the matrix addressed flatpanel display of the present invention. Data representing video, alphanumeric characters, or video data typically arrives in the system 100 via a serial data bus 110. It is then transferred through a buffer 120 into a memory 150. The buffer 120 also generates a synchronization signal, which is passed on to the timing circuit 130.

“A microprocessor 140 manages the data in the memory 150. If the data is video, and not information defining alphanumeric character codes, it is sent directly to shift register 170 as bitmap data represented by flow line 194. To actuate the anode driver 180, the shift register 170 uses received bitmap data. FIG. FIG. 3.”

“If the data entering the system 100 is alphanumeric characters the microprocessor 140 transfers the data from the memory 150 to the character generator 160. This feeds the information necessary to define the desired character to the shift register 170, which controls the operation of the anode drive 180. The shift register 170 also refreshes the images displayed on the display panel.

“The timing circuit 130 sends timing signals to the cathode and anode drivers 180, 190. This allows them to synchronize the operation of the cathode and anode drives 180 and 190. Only the anode driver 180 is concerned with actual data and the corresponding bitmap images that will be displayed by the display panel. The cathode driver’s sole responsibility is to provide synchronization with anode drivers 180 in order to present the desired image on display panel 192.

“In FIG. 1. The serial data bus 110 determines the mode of presentation, including screen resolution, color, and other attributes, on the display panel. The buffer 120 would use the data to send the appropriate synchronization signal 130 to the timing circuit 130. This would then send timing signals 180 and 190 to the anode and cathode driver 190 to ensure the image is displayed in the right synchronization. The data would be provided by the microprocessor 140 to the memory 150. This would then send any video or graphics data to shift register 170 or alphanumeric data into the character generator 160. To present the correct images on the display panel 192, the shift register 170 and anode drivers 180 would work as described previously.

“Referring to FIG. “Referring next to FIG. 2, you will see a typical operation for the embodiment of this invention at two locations. A cathode strip 200 has multiple field emitters 210 to 220, 235, 230, 244, and 250 to 260, 270, and 280 respectively for each pixel. This reduces the failure rate of each pixel and increases its lifetime and manufacturing yield. Each emitter (210, 220-230, 230 and 240 for each pixel) has an independent resistive coating. This means that other emitters for the same pixels will continue to emit electrons even if one emitter fails. Anode strip 220 will still be excited by electrons if field emitter 230 is not working. This happens because anode strips 290 and 200 cross each other. Field emitters 210 and 220 are still available. Except for the rare event of all field emitters being unable to operate at a particular pixel location, this redundancy will take place at every pixel location. Field emitters 250, 262, 270, 280, and 280 would have to all fail to make the pixel location at crossing of cathode strips 292 and 200 inoperable.

“As mentioned previously, current-limiting anode/cathode drivers can be used to reduce field emission variation. These drivers are available commercially (voltage driver chips like the Texas Instruments serial numbers 755,777 or 751,516). Current-limiting drivers are capable of generating the same operating current/voltage Q points as all other pairs as long as it exceeds the voltage necessary to cause the cathode/anode pairing with the highest threshold emission voltage to activate.

FIG. 3 shows an example of the principle behind this method. 3. shows the current-voltage curve of a diode display. V0 could be the voltage at which drivers are biased. Display brightness and intensity can be adjusted by changing V0 to V1. You can also change I0 to adjust the display’s brightness or intensity. FIG. 5 shows how to connect the current-limiting drivers and the display. 5.”

“Turning Now to FIG. 4. As mentioned previously, F-N theory states that the current density of field emission changes by up to 10 percent when cathode/anode separator separation changes only by 1 percent. This variation can be reduced by interposing a resistive element between each of the cathodes and their corresponding cathode conductor, as described in Ser. No. 07/851,701. Interposing the resistive elements can cause a voltage drop across them, and a corresponding power loss, which can increase the overall power consumption. Sometimes, the additional power consumption can be acceptable.

“FIG. “FIG. 4” illustrates an arrangement that uses a resistive element in the cathode to reduce field variation. A first method of providing the proper spacing in flat-panel diode displays is also shown. FIG. FIG. 4 shows a cathode substrate 400. A cathode substrate 400 is covered by a cathode conductive layer 420, an conductive pillar 444, a resistive element 455, and an emission material 465.

A material with a threshold electric field of less than 50 Megavolts per square meter is considered low-effective work-function material (“MV/m ). Amorphic diamond is an example of a low-effective work-function material. It is a non-crystalline carbon that has been prepared without hydrogen. It also has diamond-like properties, as described by Collins et.al., The Texas Journal of Science vol. 41, no. 4th of April 1989, Thin Film Diamond”. pp. 343-58), cermets (defined as any of a group of composite materials made by mixing, pressing and sintering metal with ceramic or by thin film deposition technology, such as graphite-diamond, silicon-silicon carbide and tri-chromium monosilicide-silicon dioxide) or coated micro-tips (which have been either randomly or photo-lithographically fabricated).”

“In addition, FIG. “In FIG. 4, there is an anode substrate (410) upon which is deposited the cathodoluminescent coating 430. The pillar 470 ensures that the cathodoluminescent layers 430 and 460 are separated by a proper space. The preferred embodiment of the invention has the following components: the cathode substrate 400 consists of glass; the cathode-conductive layer 420 consists of a metal trace such as copper; the conductive pillar 405 consists amorphic, thin-film amorphic glass; the anode substrate 410 consists mainly glass; the cathodoluminescent layers 430 and 470 are ITO, while the pillar 475 is made up of a dielectric

A diode display requires that a pillar has a breakdown voltage greater than the electron extraction field. The electron extraction field for a cathode made of amorphic, diamond film is around 15-20 MV/m. However, a diode-field emission display has shown that pillars have a breakdown potential of around 5 MV/meter. This is due to electron-induced conductivity on the surface. FIG. 4. The goal of spacing well is to increase the distance between the cathode and the anode in order to minimize the effect of electron-induced conductivity. In order for current to travel along surface 480 in FIG., it must follow a circuitous route. 4. FIG. 4 The cathode, anode, and cathode conductors can be separated by 100 micorns. While the emission surface of both the cathode or anode conductor is separated by 20 microns, the two conductors can be seen separated by the cathode.

“Turning to FIG. 5 is another method of ensuring proper spacing in a flat diode display panel, which is used in the preferred embodiment. This second method is superior to the one shown in FIG. 4. It requires only 1000-2000 spacers for a flat panel display as opposed to the 200,000-1,000,000 required by the first method. FIG. 5 shows the procedure. 5 shows how a spacer (470) is placed within a recess of 510 in the cathode substrat 400. You can make the spacer 470 from tungsten, molybdenum or aluminum. The spacer 470 is conductive due to the separation of the emission material (460) from the cathodoluminescent layers (430). This discourages electron-induced conduction. You can also make the spacer 470 from an insulating material such as silicon dioxide. The cathode substrate 400 has a number of recesses 510 that are small enough to hold the spacers. They measure between 25-50 microns in size and 75-250 millimeters deep. They can be spaced at 0.5 cm, and should be located between individual anode and cathode stripes. FIG. 5 shows the structure. FIG. 5 shows the structure. The cathode, anode, and conductors 420 and 430 are separated 20 microns. The emission material 460, 430, and the anode-conductive layer 430 are roughly separated by the same distance. Preferably, spacers are 30 microns in size.

Referring to FIG. 6. A diode biasing circuit 600 drives the display 192 at an operating voltage of a threshold potential. This is required by the low-effective work-function material deposited onto the cathode. The threshold voltage is applied between an ode strip610 and a cathode strips620. This causes electrons to be emitted from the field emitter 630 to anode 610. The anode610 is patterned with three sets of stripes and each one covered with a cathodoluminescent substance to provide full color display. A cathode 622 is used to address pixels. It is located perpendicularly to an anode strip 610. The 25 volt driver 655, which addresses the cathode strip 622, and the 25 volt driver 646, which drives anode strips 610 and 620 respectively, is used. A second 25 volt driver 642, which is powered by a 250-volt DC power supply, is used to drive the anode strip 6. The display’s threshold voltage is reached by the output voltage of 250 V from the DC power supply. These electrodes can be sequentially addressed to display a color or monochrome image. These voltages are not representative of all possible combinations and can be changed by others. Other thin film cathodes might require different threshold potentials to emit field radiation.

“FIG. 7 shows how emission from a cathode can be obtained at a location near a pixel by addressing the anode and cathode strips within the display with the voltage drivers 640 and 650.

Referring to FIG. 8 shows the top view of the flat panel LCD display 192. It illustrates the anode-cathode base structure that is used to present images onto the display. As shown in FIGS. 8 and 9, an anode 820 is joined to a cathode 810 in a perpendicular relation. 2, and 6 on a printed circuitboard (PCB), 800 or another suitable substrate. The typical semiconductor mounting technology provides external contacts 830 to the cathode assembly, and external contacts 840 to the anode assembly.

“A combination of current-limiting drivers and resistive elements is a great way to reduce field variation, as we have already mentioned. The drivers control the total display current, while the resistive elements reduce field variation between different cathode/anode pairs or within specific portions of those pairs. Resistive elements also help limit current in the event that a specific cathode/anode pair is shorted together (such as there is no gap between cathode, and anode). FIG. FIG. 8 shows 8 current-limiting drivers, which are not shown. They each have a plurality voltage outputs that are coupled in a traditional manner to the contacts 830 and 840. This provides the contacts 830 and 840 with the appropriate voltages to control their display. The current-limiting voltage drivers reduce current delivery to the contacts 830 and 840 as described in FIG. 3.”

“Turning to FIG. 9 shows the cross-section 9-9 of the display panel. 192. 8. The PCB 800 is used for mounting the anode and cathode assemblies 810 and 820 with well-known technology. FIG. 6 shows the cathode assembly (620). FIG. 6 shows one row of a 1000-gauge cathode strip. 11. Connectors 830 allow you to access the cathode strip 1000 from the outside. Anode 820 and cathode 810 are joined together by a peripheral glass frit sealing 1010. Spacers 910 ensure proper electron emission by maintaining the required anode-cathode spacing. Spacers 910 can be made of glass fibers, glass balls, or a fixed spacer that is implanted using well-known deposition technology.

An exhaust tube 1020 is used in conjunction with a vacuum pump (not illustrated) to maintain a vacuum between the anode 820 and cathode 810. The panel is sealed when the vacuum in the space 920 between the anode assembly 820 and the cathode assembly 810 reaches 10-6 Tort. If the vacuum is not too high, the exhaust tube 1020 can be closed. The getter 1030 is used for attracting undesirable elements to outgassing from various materials used in the construction of the display. A getter is typically made of a material with strong chemical affinity for other substances. Barium, for example, could be used as a filament getter. It would fit into the space 920 which is a vacuum sealed to extract any residual gases.

“Referring to FIG. 10 is shown the cross-section 10–10. 8 shows the cathode strip 1000 in their perpendicular relationship with the anode strip 900 in more detail. The 1000 cathode strips are sufficiently spaced apart to permit isolation between the 1000 strips. These are the external connectors 840 and 820 to the anode assemblies 820.

“Observe the perpendicular relationship between the anode strips (900) and the cathode strip 1000 (FIGS. It is clear from FIGS. 2-10 that the present invention allows matrix addressing of particular pixels within the display panel. FIG. 2 shows how the present invention addresses pixels. 1. Anode drivers 180 provide a voltage driver to a specific anode strip of 900, while cathode driver 190 provide a voltage driver to a cathode strips 1000. External connectors 840 connect the anode strips 900 to the anode drivers 180. External connectors 830 connect the cathode driver 190 to the cathode strip 1000. The voltage drivers of the respective cathode strips 1000 and 900 drive a particular “pixel”. The driver voltage applied at the anode drive 180 and the driver voltage applied at the cathode drivers 190 create a threshold potential. This results in electrons being released from the cathode strips 1000 to the theode strips 900. Light is also emitted by the low-energy phosphor applied on the anode 900 at the location where the perpendicularly arranged anode stripes 1000 and 900 cross paths.

Referring to FIG. “Referring now to FIG. 11, you will see a detailed illustration showing a pixel” 1100. The cathode assembly 810 is made up of a substrate 1110 (typically glass), a resistive and conductive layers 1160, and flat cathodes 170. A cathode strip 1000 is made up of the resistive layer 1160, conductive layer 1150 and flat cathodes 170. Each flat cathode 1170 is spaced apart, resulting in isolation maintained by resistive layer 1160. Anode assembly 820 is composed of a substrate 1120 made of glass and a conductive layer 1130 made from low-energy phosphors 1140 such as ZnO.

“The pixel 11100 is illuminated when a sufficient voltage is applied to conductive layer 1150 on the cathode strips 1000 that corresponds to the pixel 11100. A sufficient driver voltage also applies to ITO conductive layers 1130 and 900 that correspond to the particular pixel 11100. Combining the two driver voltages with the constant DC supply, the total threshold potential between sections of the anode strips 900 and 1000 is sufficient to illuminate the pixel 1100. The total threshold potential causes electron emission from the flat cathodes 1170 and the low energy phosphor 1400, which in turn emit light.

“As can be seen in FIGS. 2, 11 and 2 each cathode strip 1000 uses a multitude isolated flat cathodes 170 that illuminate the pixel 1100, even if some or all of the flat cathodes 970 fail. The remaining flat cathodes 110 will continue to work.

“Referring to FIG. 12 shows an implementation of grey scale mode on flat panel display 192. The anode strips 990 and the cathode strips 1000 are laid perpendicularly. Each anode strip 1000 may be subdivided into smaller strips 1200-1220, 1230 or 1240 of equal widths. Each subdivision is separated from its neighboring subdivisions by a sufficient gap. Each of the sub-strips 1200, 1220 and 1230 can be addressed independently by the anode drivers 180. A pixel 1100 can be illuminated in grey scale mode. If subdivisions 1200, 1230 and 1240 receive a driver voltage from their respective anode drivers 180 and subdivisions 1210-1220 and 1240 do not receive a driver current, then only the low-energy phosphor associated to subdivisions 1200 or 1230 will activated by the corresponding cathode strips 1000, which will result in less illumination than the pixel 1100.

“As you can see, the subdivisions 1210, 1220 and 1230 may be activated in different combinations to provide different intensities of illumination for the pixel 1100. Each subdivided strip is of different sizes and can be related by powers of 2. For example, if there are five strips with relative sizes of 1, 2, 4, 8, 16 and 16, then activation can be done in discrete steps from 0 to 32 to produce a greyscale. If you want a pixel intensity of 19, the strips 16 and 2 must be activated.

The present invention is unique in that it provides a flat panel display consisting of 1) a cathode with a plurality cathodes and 2) an anode assembled having a plurality anodes. Each anode includes a layer cathode-conductive material and a coating of low-effective work-function material. The anode is located near the cathode to receive the charged particle emission from the cathode.

“Even though the advantages of the present invention have been explained in detail, it is important to understand that many modifications, substitutions, and alterations may be made without departing from its spirit and scope as described by the attached claims.”

Summary for “Diode structure flat panel display”