Patent Grant
6879097
This invention relates to flat-panel displays of the cathode-ray-tube (“CRT”) type.
A flat-panel CRT display basically consists of an electron-emitting device and a light-emitting device. Electrons emitted by the electron-emitting device, commonly referred to as a cathode, strike the light-emitting device and cause it to emit light that produces an image on the viewing surface of the display.
Light-emitting device 12 consists of transparent faceplate 30, an array of equally spaced rows and equally spaced columns of light-emissive regions 32, black matrix 34, and light-reflective anode layer 36 arranged as shown in FIG. 1. Each light-emissive region 32 is situated directly opposite a corresponding different one of electron-emissive regions 22. Upon being selectively struck by electrons emitted by regions 22, light-emissive regions 32 emit light to produce an image on the exterior surface of faceplate 30 at the front of the display.
As indicated in
The present invention furnishes a flat-panel CRT display in which a group of electron-emissive regions situated in a line are non-uniformly spaced apart from one another so as to provide better utilization of the space where the electron-emissive regions are located. A spacer, typically a spacer wall, can readily be positioned above the space between one pair of consecutive electron-emissive regions whose separation is greater than the separation between another pair of consecutive electron-emissive regions. Due to the non-uniform spacing of the electron-emissive regions, the presence of such a spacer wall places less restriction on the dimensions of the electron-emissive regions in the direction perpendicular to the spacer wall than would occur if the electron-emissive regions were spaced uniformly apart from one another in that direction. The lateral dimensions of the electron-emissive regions in the present flat-panel display can thereby be made greater in the direction perpendicular to the spacer wall than could otherwise reasonably be achieved.
More particularly, a flat-panel CRT display having improved space utilization in accordance with the invention contains an electron-emitting device and a light-emitting device which together act to produce an image. The electron-emitting device has at least three laterally separated electron-emissive regions arranged in a line extending in a main direction. Each pair of consecutive electron-emissive regions in the line is at a center-to-center spacing which is at least 3% greater in the main direction for one pair of consecutive electron-emissive regions than for another pair of consecutive electron-emissive regions. A spacer, e.g., a spacer wall, is typically situated between the electron-emitting and light-emitting devices above the space between a pair of consecutive electron-emissive regions whose center-to-center spacing is at least 3% greater in the main direction than that of another pair of consecutive electron-emissive regions.
The light-emitting device similarly has at least three light-emissive regions arranged in a line extending in the main direction. Each light-emissive region is situated generally opposite a corresponding different one of the electron-emissive regions. Upon being struck by electrons emitted by one of the electron-emissive regions, the corresponding oppositely situated light-emissive region emits light to produce at least part of a dot of the display's image. In contrast to the electron-emissive regions, the light-emissive regions are normally of approximately uniform center-to-center spacing in the main direction. Consequently, certain of the light-emissive regions are slightly laterally offset from the corresponding electron-emissive regions in the main direction.
The present flat-panel display normally includes a system for focusing electrons emitted by each electron-emissive region on the corresponding light-emissive region. The electron-focusing system has at least three focus openings arranged in a line extending generally in the main direction. Each focus opening is located at least partially, typically substantially fully, above a corresponding different one of the electron-emissive regions so that electrons emitted by each electron-emissive region pass at least partially, typically substantially fully, through the corresponding focus opening. In focusing the electrons emitted by the electron-emissive regions respectively on the corresponding light-emissive regions, the electron-focusing system appropriately compensates for any lateral offset of certain of the light-emissive regions to the corresponding electron-emissive regions in the main direction. This compensation is typically achieved by arranging for each electron-emissive region and the corresponding focus opening to be at a suitable non-zero center-to-center spacing in the main direction.
The electron-emissive regions are preferably allocated into alternating first and second pairs of consecutive electron-emissive regions for which each second pair of consecutive electron-emissive regions is at a greater, normally at least 3% greater, center-to-center spacing in the main direction than each first pair of consecutive electron-emissive regions. A spacer, e.g., again a spacer wall, is typically situated between the electron-emitting and light-emitting devices above the space between one of the second, more widely separated, pairs of consecutive electron-emissive regions. For the normal case in which the light-emissive regions are uniformly spaced apart in the main direction, the present display utilizes the electron-focusing system to compensate for the resultant lateral offset of the light-emissive regions to the electron-emissive regions.
Each electron-emissive region may be divided into two or more electron-emissive portions laterally separated in the main direction. In that case, the focus opening corresponding to each electron-emissive region is replaced with two or more focus openings, each located at least partially above a corresponding different one of the electron-emissive portions of that electron-emissive region. The compensation for the lateral offset of certain light-emissive regions to the corresponding electron-emissive regions in the main direction is then achieved by arranging for the composite center of the electron-emissive portions of each of certain of the electron-emissive regions to be appropriately laterally separated in the main direction from the composite center of the focus openings above those electron-emissive portions.
The present invention also furnishes a flat-panel CRT display having highly concentrated electron focusing. In particular, this further display is designed so that electrons emitted by an electron-emissive region of the display's electron-emitting device converge generally on a narrow location in an oppositely situated light-emissive region of the display's light-emitting device. The concentrated electron focusing enables the average distance between the electron-emitting and light-emitting devices to be increased, thereby permitting the voltage applied to an anode in the electron-emitting device to be made higher relative to the average voltage applied to the electron-emissive region. Increasing the anode voltage, in turn, enables the display to operate more efficiently and results in longer display life. Alternatively or additionally, the average electric field in the space between the electron-emitting and light-emitting devices can be reduced so as to improve display reliability and decrease the likelihood of electrical arcing.
The electron-emissive region in the display with concentrated electron focusing is divided into a pair of laterally separated electron-emissive portions. Electrons emitted by the electron-emissive portions pass respectively at least partially through a pair of at least partially overlying focus openings in an electron-focusing system of the electron-emitting device. The concentrated electron focusing is achieved by arranging for the two electron-emissive portions of the electron-emissive region to be at a greater lateral center-to-center spacing than the two focus openings. With one or more suitable voltages applied to the electron-focusing system, configuring the focus openings in this manner relative to the electron-emissive portions enables the electron-focusing system to act like a convergent lens. After passing through the focus openings, the electrons emitted by the electron-emissive portions thus converge generally on a line of the light-emissive region.
The configuration feature which enables space in the electron-emitting device to be used more efficiently can be combined with the electron-focusing concentration feature. In a typical implementation, electron-emissive regions situated in a line are non-uniformly spaced apart from one another in one direction in order to improve the space utilization while each electron-emissive region is divided into a pair of electron-emissive portions laterally separated from each other in another direction largely perpendicular to the first-mentioned direction. With all the electron-emissive portions being exposed through respective overlying openings in an electron-focusing system, the two electron-emissive portions of each electron-emissive region are at a greater center-to-center spacing than the two overlying focus openings so as to achieve concentrated electron focusing. In short, the invention provides substantial advantages over conventionally organized flat-panel CRT displays.
Like reference symbols are employed in the drawings and in the description of the preferred embodiments to represent the same, or very similar, item or items.
General Considerations
Various structures are described below for a flat-panel CRT display configured according to the invention to enhance space utilization in the display's electron-emitting device or/and achieve concentrated electron focusing. Each of the present flat-panel CRT displays, typically of the field-emission type, is generally suitable for a flat-panel television or a flat-panel video monitor for a personal computer, a laptop computer, a workstation, or a hand-held device such as a personal digital assistant.
The electron-emitting device in each of the present flat-panel CRT displays contains a two-dimensional array of electron-emissive regions arranged in rows and columns. The display's light-emitting device similarly contains a two-dimensional array of light-emissive regions arranged in rows and columns. Each light-emissive region is situated generally opposite a corresponding one of the electron-emissive regions.
A flat-panel CRT display produces its image in an active region of the display. The active region consists of an active light-emitting portion of the light-emitting device, an active electron-emitting portion of the electron-emitting device, and the space between the active light-emitting and electron-emitting portions. The active light-emitting portion extends from the first row of light-emissive regions to the last row of light-emissive regions and from the first column of light-emissive regions to the last column of light-emissive regions. The active electron-emitting portion similarly extends from the first row of electron-emissive regions to the last row of electron-emissive regions and from the first column of electron-emissive regions to the last column of electron-emissive regions.
Each of the present flat-panel displays is typically a color display but can be a monochrome, e.g., black-and-green or black-and-white, display. Each light-emissive region and the corresponding oppositely situated electron-emissive region form a pixel in a monochrome display, and a sub-pixel in a color display. A color pixel typically consists of three sub-pixels, one for red light, another for green light, and the third for blue light. Each pixel, whether color or monochrome, provides a dot of the image produced by the display. A subpixel in a color display thus provides part of a dot of the display's image.
The electron-emitting device in each of the present flat-panel displays contains a group of control electrodes for controlling the magnitudes of the electron currents travelling to the oppositely situated light-emitting device. When the electron-emitting device operates according to field (cold) emission, the control electrodes extract electrons from the electron-emissive elements. An anode in the light-emitting device attracts the extracted electrons toward the light-emissive regions.
When the electron-emitting device contains electron-emissive elements which continuously emit electrons during display operation, e.g., by thermal emission, the control electrodes selectively pass the emitted electrons. That is, as electrons are emitted under conditions which, in the absence of the control electrodes, would enable those electrons to go past the locations of the control electrodes. The control electrodes permit certain of those electrons to pass the control electrodes and collect the remainder of those electrons or otherwise prevent the remaining electrons from passing the control electrodes. The anode in the light-emitting device attracts the passed electrons toward the light-emissive regions.
In the following description, the term “electrically insulating” or “dielectric” generally applies to materials having a resistivity greater than 1010 ohm-cm at 25° C. The term “electrically non-insulating” or “non-dielectric” thus refers to materials having a resistivity of no more than 1010 ohm-cm at 25° C. Electrically non-insulating or non-dielectric materials are divided into (a) electrically conductive materials for which the resistivity is less than 1 ohm-cm and (b) electrically resistive materials for which the resistivity is in the range of 1 ohm-cm to 1010 ohm-cm at 25° C. Similarly, the term “electrically non-conductive” refers to materials having a resistivity of at least 1 ohm-cm, and includes electrically resistive and electrically insulating materials. These categories are determined at an electric field of no more than 10 volts/μm.
Flat-Panel Display Having Line of Non-uniformly Spaced Electron-Emitting Regions
A spacer system is situated between devices 40 and 42 inside enclosure 44 for resisting external forces exerted on the flat-panel display and for maintaining a relatively uniform separation between devices 40 and 42. In particular, the spacer system prevents the external-to-internal pressure difference of approximately 1 atm. from collapsing the display. The spacer system here consists of a group of spacer walls 46 extending general parallel to one another in a direction referred to here as the row direction. One such spacer wall 46 is indicated in
Each of spacer walls 46 normally consists of a main wall (not separately shown) and one or more electrodes (also not separately shown) situated over the main wall. For instance, each spacer wall 46 may contact devices 40 and 42 through a pair of respective edge electrodes situated over opposite edges of that spacer's main wall. Face electrodes may overlie the face (side) surfaces of the main walls for controlling the trajectories of electrons moving from electron-emitting device 40 to light-emitting device 42. Exemplary configurations for spacer walls 46 are presented in U.S. Pat. Nos. 5,990,614, 6,049,165, and 6,107,731.
Electron-emitting device, or backplate structure, 40 is formed with a generally flat electrically insulating backplate 50 and a group of layers and regions 52 situated over the interior surface of backplate 50. Layers/regions 52 include a two-dimensional array of rows and columns of laterally separated electron-emissive regions 54. The rows of electron-emissive regions 54 are largely straight and extend laterally in the row direction. The columns of regions 54 are likewise largely straight and extend laterally perpendicular to the row direction in a direction referred to here as the column direction. The number of columns of regions 54 is at least three and is normally considerably greater than three. The same applies to the number of rows of regions 54. Each region 54 consists of one or more electron-emissive elements (not separately shown here) which emit electrons directed toward light-emitting device 42.
The spacings between consecutive rows of electron-emissive regions 54 are non-uniform in the flat-panel display of
More particularly, the center of a row of electron-emissive regions 54 is a line that extends in the row direction and goes through the centers of regions 54 in that row. The center-to-center spacing between each first pair of consecutive rows of regions 54 is largely the same for all the first pairs of consecutive rows of regions 54. The center-to-center spacing between each second pair of consecutive rows of regions 54 is likewise largely the same for all the second pairs of consecutive rows of regions 54. Let SEC1 represent the (average) center-to-center spacing between each first pair of consecutive rows of regions 54. Similarly let SEC2 represent the (average) center-to-center spacing between each second pair of consecutive rows of regions 54. Center-to-center spacing SEC2 of the second pairs of consecutive rows of regions 54 is normally at least 3% greater than, preferably at least 5% greater than, more preferably at least 10% greater than, and even more preferably at least 20% greater than, center-to-center spacing SEC1 of the first pairs of consecutive rows of regions 54.
Alternatively stated, each column of electron-emissive regions 54 in the display of
Electron-emissive regions 54 can be configured laterally in various ways. Regions 54 are typically of largely the same size, of largely the same orientation, and are largely laterally symmetrical about their centerlines (not shown) in the row direction.
More generally, electron-emissive regions 54 are configured so that (as viewed perpendicular to backplate 50) regions 54 in each row are largely mirror images, relative to the row direction, of regions 54 in each directly adjacent row. In other words, regions 54 in alternating rows are largely mirror images, relative to the row direction, of regions 54 in the remaining alternating rows. The layout of
A pixel, whether color or monochrome, is typically largely square as seen from the front of a flat-panel display. The display of
Electron-emissive regions 54 are spaced largely uniformly apart from one another in the row direction in the display of
Each spacer wall 46 is located above (part of) the space between one of the second pairs of consecutive rows of electron-emissive regions 54, i.e., above the space between a pair of the more widely separated rows of regions 54. In particular, each spacer wall 46 is preferably equidistant from the two nearest rows of regions 54 on opposite sides of that wall 46. From a column perspective, each wall 46 is located above the space between, and preferably centered on that space between, one of the second pairs of consecutive regions 54 in each column.
There are normally considerably less spacer walls 46 than second pairs of consecutive rows of electron-emissive regions 54. Hence, no walls 46 are normally located over the spaces between many of the second pairs of consecutive rows of regions 54. There is normally only one wall 46 for every 30-40 rows of regions 54. Walls 46 are also normally distributed approximately uniformly across the active region of the display. Accordingly, one wall 46 is located above the space between every fifteenth to twentieth pair of consecutive rows of regions 54.
Several benefits arise from locating each spacer wall above the space between one of the second pairs of consecutive rows of electron-emissive regions 54. Firstly, more dimensional tolerance in appropriately positioning spacer walls 46 on electron-emitting device 40 is available when they are positioned over the spaces between the more widely separated pairs of consecutive rows of regions 54 than what would occur if the rows of regions 54 were spaced uniformly apart. Slight deviations from the desired target positions of walls 46 can be better tolerated in the display of
Secondly, the presence of spacer walls 46 constrains the dimensions of electron-emissive regions 54 in the column direction, i.e., in the direction perpendicular to walls 46. By configuring the rows of regions 54 as alternating more widely separated and more narrowly separated pairs of consecutive rows of regions 54 and placing each spacer wall 46 over the space between a pair of more widely separated consecutive rows of regions 54, less constraint is placed on the dimensions of regions 54 in the column direction than would arise if consecutive rows of regions 54 were uniformly spaced apart. For a given lateral area of the active display region and a given number of rows of regions 54, the dimensions of regions 54 can be increased in the column direction, thereby yielding a more robust display. The voltages needed to switch regions 54 can also be reduced somewhat.
Thirdly, spacer walls 46 invariably disturb the trajectories of electrons traveling from electron-emissive regions 54 to light-emitting device 42. The disturbance that each spacer wall 46 produces on the electron trajectories is normally greatest on the trajectories of the electrons emitted by regions 54 in the two nearest rows of regions 54 on opposite sides of that wall 46, i.e., on the trajectories of electrons traveling closest to that wall 46. Compared to what would happen if regions 54 were spaced uniformly apart from one another, positioning walls 46 above the locations between more widely separated pairs of consecutive rows of regions 54 increases the average distance from each region 54 to the nearest electrons traveling from electron-emitting device 40 to light-emitting device 42. Consequently, less disturbance of the electron trajectories is caused by walls 46 in the display of
Light-emitting device, or faceplate structure, 42 is formed with a generally flat electrically insulating faceplate 60 and a group of layers and regions 62 situated on the interior surface of faceplate 60. Faceplate 60 is transparent, i.e., generally transmissive of visible light, at least where visible light is intended to pass through faceplate 60 to produce an image on the exterior surface (upper surface in
Light-emissive regions 64 emit light upon being struck by electrons. Each region 64 is situated generally opposite a corresponding different one of electron-emissive regions 54. The electrons emitted by each region 54 are thereby intended to strike corresponding light-emissive region 64 to produce suitable light.
The rows of light-emissive regions 64 are largely straight and extend in the row direction. The columns of regions 64 are likewise largely straight and extend in the column direction. In the display of
As indicated in
With the center-to-center spacing between pairs of consecutive rows of electron-emissive regions 54 alternating between spacing SEC1 and spacing SEC2 in the display of
Light-emissive regions 64 are also spaced largely uniformly apart from one another in the row direction in the display of
Black matrix 66 laterally surrounds each light-emissive region 64 and appears dark, largely black, as viewed from the front of the display. Matrix 66 enhances the contrast of the display's image. In the example of
The anode (again not shown) in the display of
The display of
The display in
Electron-emitting device 40 in the field-emission flat-panel CRT display (“field-emission display”) of
Lower non-insulating region 70 contains a group of laterally separated generally parallel emitter electrodes (not separately shown) situated on backplate 50. The emitter electrodes extend longitudinally in the column direction. Non-insulating region 70 also normally includes an electrically resistive layer (likewise not separately shown) which overlies the emitter electrodes and, dependent on its lateral shape, may extend down to backplate 50 in the spaces between the emitter electrodes. At a minimum, the resistive layer underlies electron-emissive regions 54.
Dielectric layer 72 lies on lower non-insulating region 50 and, dependent on the shape of the resistive layer, may extend down to backplate 70 in the spaces between the emitter electrodes. Each electron-emissive region 54 consists of multiple electron-emissive elements 78 situated largely in openings (not explicitly shown) extending through dielectric layer 72. Electron-emissive elements 78 of each region 54 are situated on a portion of the resistive layer above one of the emitter electrodes. Each element 78 typically consists of a cone or filament formed with metal such as molybdenum.
Control electrodes 74 lie on dielectric layer 72 and extend longitudinally generally parallel to one another in the row direction. Each control electrode consists of a main control portion 80 and an adjoining gate portion 82 situated above or below main control portion 80.
Gate portion 82 of each control electrode 74 may extend continuously across the active portion of electron-emitting device 40 or may be divided into laterally separated segments, typically one for each electron-emissive region 54 controlled by that electrode 74. In addition to the associated electron-emissive elements 78, each region 54 may be deemed to include the underlying part of the associated emitter electrode and the overlying part of associated gate portion 82.
Electron-focusing system 76 is situated on dielectric layer 72 and extends over control electrodes 74. A group of focus openings 86 arranged in rows and columns respectively corresponding to the rows and columns of electron-emissive regions 54 extend through system 76 down to electrodes 74. Accordingly, there at least three, and normally considerable more than three, focus openings 86 in each row of openings 86. The same applies to the columns of openings 86.
A suitable focus potential is applied to electron-focusing system 76 from an appropriate voltage source (not shown). An example of the internal configuration of system 76 is presented later in FIG. 21. In any event, system 76 is normally configured so that material carrying the focus potential extends from the tops of focus openings 86 at least partway down into each of them. Material carrying the focus potential also typically extends along the top of system 76.
Each focus opening 86 is located above a corresponding different one of electron-emissive regions 54 so as to fully expose that region 54 to enclosure 44. As viewed perpendicular to backplate 50, the lateral boundary of each region 54 is preferably fully situated within the lateral boundary of corresponding opening 86. Electrons emitted by each region 54 pass through overlying opening 86 on their way to light-emitting device 42.
Analogous to electron-emissive regions 54, focus openings 86 can be configured laterally in various ways. Openings 86 are typically of largely the same size, of largely the same lateral orientation, and are largely laterally symmetrical about their centerlines (not shown) in the row direction.
In general, focus openings 86 are configured so that (as viewed perpendicular to backplate 50) openings 86 in each row are largely mirror images, relative to the row direction, of openings 86 in each directly adjacent row. Hence, openings 86 in alternating rows are largely mirror images, relative to the row direction, of openings 86 in the remaining alternating rows. Openings 86 are typically configured in this alternating mirror-image arrangement when electron-emissive regions 54 are configured, as described above, in a corresponding alternating mirror-image arrangement relative to the row direction. The layout of
Focus openings 86 are positioned above electron-emissive regions 54 so as to enable electron-focusing system 76 to compensate for the lateral offsets of light-emissive regions 64 to corresponding electron-emissive regions 54 in the column direction. The compensation is achieved by appropriately offsetting the positions of openings 86 in the column direction relative to the positions of electron-emissive regions 54 in the column direction. That is, each region 54 and corresponding opening 86 are at a suitable non-zero center-to-center spacing in the column direction. The offset of each opening 86 to underlying region 54 is normally in the same absolute direction, but at a lesser magnitude, than the offset of corresponding light-emissive region 64 to that electron-emissive region 54.
More particularly, let the column direction to the right in
As
The opposite arises with a light-emissive region 64, such as the second one starting from the left-hand side of
Offset spacing dEFCR is less than spacing offset spacing dELCR as indicated in
The pair of focus openings 86 overlying each first, more narrowly separated, pair of electron-emissive regions 54 are at a center-to-center spacing SFC1 in the column direction. In light of the foregoing offset of openings 86 to underlying regions 54, center-to-center focus spacing SFC1 is the sum of center-to-center electron-emission spacing SEC1 and offset spacings dEFCL and dEFCR. Center-to-center electron-emission spacing SEC1 is thus less than center-to-center focus spacing SFC1. In other words, each first pair of regions 54 is at a lesser center-to-center spacing in the column direction than the pair of respectively overlying openings 86.
The opposite arises with each second, more widely separated, pair of electron-emissive regions 54 and the respectively overlying pair of focus openings 86. This pair of openings 86 is at a center-to-center spacing SFC2 in the column direction. Center-to-center electron-emission spacing SEC2 is the sum of center-to-center focus spacing SFC2 and offset spacings dEFCR and dEFCL. As a result, center-to-center electron-emission spacing SEC2 is greater than center-to-center focus spacing SFC2. Each second pair of regions 54 is thus at a greater center-to-center spacing in the column direction than the pair of respectively overlying openings 86.
As mentioned above in connection with the display of
Layers/regions 62 in light-emitting device 42 include a thin light-reflective anode layer 88 situated over light-emissive regions 64 and black matrix 66. The display's anode potential is furnished to light-reflective anode layer 88 from a suitable voltage source (not shown). When electrons emitted by regions 54 impinge on device 42, the electrons pass through light-reflective layer 88 before striking light-emissive regions 64 and causing light emission.
As indicated in
Each electron-emissive region 54 in the display of
The spacings between consecutive rows of electron-emissive regions 54 in the display of
As indicated in
Portions 54A and 54B of electron-emissive regions 54 can be configured laterally in various ways. Portions 54A are typically of largely the same size and of largely the same orientation and lateral shape. Portions 54B are likewise typically of largely the same size and of largely the same orientation and lateral shape. More particularly, portions 54A and 54B are typically largely symmetrical about their centerlines (not shown) in the row direction. Portions 54A and 54B are typically shaped laterally generally as rectangles. Each rectangle is usually of greater dimension in the column direction than in the row direction.
In any event, the lateral separation between portions 54A and 54B of each electron-emissive region 54 is largely the same in the column direction for all regions 54. Also, any center-to-center offset between portion 54A and 54B of each region 54 in the row direction is largely the same for all regions 54.
Electron-emissive portions 54B may be largely identical to, and oriented largely the same as, electron-emissive regions 54A. Portions 54B are then of largely the same size and lateral shape as portions 54A. In that case, electron-emissive regions 54 are largely identical since the lateral column-direction spacing between, and any center-to-center row direction offset between, portions 54A and 54B of each region 54 is largely the same for all regions 54. This example is depicted in
More generally, electron-emissive portions 54A and 54B are configured so that (as viewed perpendicular to backplate 50) electron-emissive regions 54 in each row are largely mirror images, relative to the row direction, of regions 54 in each directly adjacent row. Regions 54 in alternating rows are thus largely mirror images, relative to the row direction, of regions 54 in the remaining alternating rows. The layout of
In order to achieve the alternating mirror-image layout of electron-emissive regions 54 in the FED of
Subject to the lateral column-direction spacing between, and any center-to-center row-direction offset between, portions 54A and 54B of each electron-emissive region 54 being the same for all regions 54, the alternating mirror-image arrangement of regions 54 can be achieved by configuring portions 54A or 54B in each row of regions 54 to be largely mirror images, relative to the row direction, of portions 54A or 54B in each directly adjacent row of regions 54, where the row-direction mirror-images are laterally asymmetrical about their centerlines in the row directions. The alternating mirror-image arrangement can also be achieved by configuring portions 54B to be of significantly different lateral shape than portions 54A without requiring that portions 54A or 54B be laterally asymmetrical about their centerlines in the row direction. For instance, portions 54B can simply be longer or shorter than portions 54A in the column direction.
Portions 54A and 54B of each electron-emissive region 54 have a composite center which, due to the spacing between portions 54A and 54B of that region 54, often lies between portions 54A and 54B of that region 54. The composite center of portions 54A and 54B of each region 54 is the center of that region 54. With this in mind, consecutive rows of regions 54 in the display of
Rather than being divided into two portions 54A and 54B laterally separated in the column direction, each electron-emissive region 54 can be divided into more than two electron-emissive portions laterally separated in the column direction. There are various reasons for implementing each region 54 as two or more portions laterally separated in the column direction. Since spacer walls 46 extend in the row direction, the presence of walls 46 can cause electrons emitted by regions 54, especially those regions 54 closest to walls 46, to be deflected in the column direction. When each region 54 is implemented as a unitary (continuous) region, electrons traveling from that region 54 to oppositely situated light-emissive region 64 concentrate at a location, preferably the center, of that region 64. The presence of walls 46 can degrade the image by causing electrons emitted by certain of regions 54, especially those regions 54 closest to walls 46, to concentrate at locations significantly displaced in the column direction from the centers of oppositely situated light-emissive regions 64.
The foregoing problem can be alleviated by dividing each electron-emissive region 54 into two or more electron-emissive portions laterally separated in the column direction and appropriately controlling the focusing of electrons emitted by the two or more portions of that region 54. This electron-focusing technique is further described in International Patent Publication WO 00/02081, the contents of which are incorporated by reference herein. In brief, appropriately implementing each region 54 as two or more portions, such as electron-emissive portions 54A and 54B, enables the profile of the intensity at which electrons emitted by those two or more portions strike the oppositely situated light-emissive region 64 to be flatter in the column direction. As a result, column-direction electron deflection caused, for example, by the presence of spacer walls 46 has less effect on the light provided by regions 64 and thus less damaging effect on the display's image.
Aside from configuring each of electron-emissive regions 54 as electrons-emissive portions 54A and 54B and the consequent effect of configuring regions 54 in that manner, the display of
The FED of
A group of main control openings 84A and 84B extend through main control portions 80 of control electrodes 74 respectively above electron-emissive regions 54A and 54B. The pair of main control openings 84A and 84B situated respectively above portions 54A and 54B of each electron-emissive region 54 are laterally separated in the column direction. In effect, each main control opening 84 in the FED of
A group of focus openings 86A and 86B extend through electron-focusing system 76 down to control electrodes 74. Each focus opening 86A and 86B is located above a corresponding different one of electron-emissive portions 54A or 54B so as to fully expose that portion 54A or 54B. As viewed perpendicular to backplate 50, the lateral boundary of each portion 54A or 54B is preferably situated fully within the lateral boundary of corresponding opening 86A or 86B. Electrons emitted by each portion 54A or 54B pass through overlying opening 86A or 86B on their way to light-emitting device 42. As with focus openings 86 in the FED of
The pair of focus openings 86A and 86B which respectively expose portions 54A and 54B of each electron-emissive region 54 are laterally separated in the column direction. Openings 86A and 86B thereby form an array of rows and columns in which each row (extending in the row direction) consists solely of openings 86A or solely of openings 86B. Each column (extending in the column direction) consists of an opening 86A followed by a pair of openings 86B, a pair of openings 86A, a pair of openings 86B, and so on in an alternating pair arrangement. Each focus opening 86 in the FED of
Analogous to both focus openings 86 in the FED of
Let a “pair” of focus openings 86A and 86B here mean two directly adjacent openings 86A and 86B that respectively expose portions 54A and 54B of an electron-emissive region 54. The lateral spacing between each pair of openings 86A and 86B is largely the same in the column direction for all such focus-opening pairs. In addition, any center-to-center offset between each pair of openings 86A and 86B in the row direction is largely the same for all the focus-opening pairs.
Focus openings 86B may be largely identical to, and of largely the same orientation as, focus openings 86A. Openings 86B are then of largely the same size and lateral shape as openings 86A. In that case, all the pairs of openings 86A and 86B are largely identical since the lateral column-direction spacing between, and any center-to-center row-direction offset between, each pair of openings 86A and 86B is largely the same for all the pairs of openings of 86A and 86B. This example is shown in
Let a “pair” of rows of focus openings 86A and 86B here mean two directly adjacent rows of openings 86A and 86B that respectively expose electron-emissive portions 54A and 54B of a row of electron-emissive regions 54. With that in mind, openings 86A and 86B are normally configured so that (as viewed perpendicular to backplate 50) openings 86A and 86B in each pair of rows of openings 86A and 86B are respectively largely mirror images, relative to the row direction, of openings 86A and 86B in each directly adjacent pair of rows of openings 86A and 86B. Openings 86A and 86B in alternating pairs of rows of openings 86A and 86B are thus respectively largely mirror images relative to the row direction, of openings 86A and 86B in the remaining alternating pairs of rows of openings 86A and 86B. Opening 86A and 86B are typically configured in this alternating pair mirror-image arrangement when portions 54A and 54B of a row of electron-emissive regions 54 are configured, as described above, in a corresponding alternating pair mirror-image arrangement relative to the row direction. The layout of
Subject to the lateral column-direction spacing between, and any center-to-center row-direction offset between, each pair of focus openings 86A and 86B being largely the same for all the pairs of openings 86A and 86B, the alternating pair mirror-image arrangement of openings 86A and 86B can be achieved by configuring openings 86A or 86B in each pair of rows of openings 86A and 86B to respectively be largely mirror images, relative to the row direction, of openings 86A or 86B in each directly adjacent pair of rows of openings 86A and 86B, where the row-direction mirror images are largely laterally asymmetrical about their centerlines in the row direction. The alternating pair mirror-image arrangement of openings 86A and 86B can also be achieved by configuring openings 86B to be of significantly different lateral shape than openings 86A without requiring the openings 86A and 86B be laterally symmetrical about their centerlines in the row direction. For instance, openings 86B can simply be longer or shorter than openings 86A in the column direction.
Focus openings 86A and 86B are positioned respectively above portions 54A and 54B of electron-emissive regions 54 for enabling electron-focusing system 76 to compensate for the lateral offsets of light-emissive regions 64 to corresponding electron-emissive regions 54 in the column direction. The compensation is achieved by appropriately offsetting the positions of openings 86A and/or 86B in the column direction relative to the positions of portions 54A and/or 54B in the column direction. That is, each portion 54A and overlying opening 86A are at a suitable non-zero center-to-center offset spacing in the column direction and/or each portion 54B and overlying opening 86B are at a suitable non-zero center-to-center offset spacing in the column direction. The compensation can sometimes be attained by offsetting the positions of openings 86A in the column direction relative to the positions of portions 54A in the column direction without significantly offsetting the positions of portions 86B in the column direction relative to positions of portions 54B in the column direction, and vice versa.
In utilizing focus openings 86A and 86B to compensate for the lateral offsets of light-emissive regions 64 to corresponding electron-emissive regions 54 in the column direction, each pair of openings 86A and 86B is treated as a group. More particularly, each pair of openings 86A and 86B has a composite center which, due to the separation between openings 86A and 86B of that pair, often lies between that pair of openings 86A and 86B. Subject to each electron-emissive region 54 being implemented as portions 54A and 54B laterally separated in the column direction and subject to each focus opening 86 of the FED of
Consider a light-emissive region 64, such as the first one starting from the left-hand side of
As
The opposite occurs with a light-emissive region 64, such as the second one starting from the left-hand side of
The spacing from the composite center of the pair of focus openings 86A and 86B respectively overlying portions 54A and 54B of one of the first, more narrowly separated, pairs of electron-emissive regions 54 to the composite center of the adjoining pair of openings 86A and 86B respectively overlying portions 54A and 54B of the other of that first pair of regions 54 is focus spacing SFC1. In light of the foregoing offsets of openings 86A and 86B to portions 54A and 54B of underlying regions 54, center-to-center focus spacing SFC1 is the sum of center-to-center electron-emission spacing SEC1 and offset spacings dEFCL and dEFCR. Center-to-center electron-emission spacing SEC1 is thus again less than center-to-center focus spacing SFC1. That is, each first pair of regions 54 is at a less center-to-center spacing in the column direction than the two overlying pairs of openings 86A and 86B.
The opposite arises with each second, more widely separated, pair of electron-emissive regions 54 and the two overlying pairs of focus openings 86A and 86B. The spacing from the composite center of the pair of openings 86A and 86B respectively overlying portions 54A and 54B of one of the two pairs of regions 54 to the composite center of the adjacent pair of openings 86A and 86B respectively overlying portions 54A and 54B of the other of that pair of regions 54 is focus spacing SFC2. Center-to-center electron-emission spacing SEC2 is the sum of center-to-center focus spacing SFC2 and offset spacings dEFCR and dEFCL. Accordingly, center-to-center electron-emission spacing SEC2 is again greater than center-to-center focus spacing SFC2. Hence, each second pair of regions 54 is at a greater center-to-center spacing in the column direction than the two overlying pairs of openings 86A and 86B.
In addition to being positioned to compensate for the column-direction offsets of light-emissive regions 64 relative to electron-emissive regions 54 in the FED of
Compensating solely for the column-direction offsets of light-emissive regions 64 to electron-emissive regions 54 in the FED of
Analogous to what was said above about the display of
Light-emitting device 42 and spacer walls 46 in the FED of
Implementing each electron-emissive region 54 with two portions 54A and 54B in the manner shown in
The FED of
The FED of
Additionally, the dimension of each electron-emissive portion 54A or 54B is 20-60 μm, typically 30-35 μm, in the column direction. Each portion 54A or 54B has a dimension of 5-30 μm, typically 10-15 μm, in the row direction. The dimension of each focus openings 86A or 86B is 50-150 μm, typically 90 μm, in the column direction. Each openings 86A or 86B has a dimension of 40-120 μm, typically 80 μm, in the row direction. With focus openings 86A and 86B being respectively centered on underlying portions 54A and 54B in the row direction, the spacing between each pair of openings 86A or 86B in the row direction is 50-150 μm, typically 90-95 μm.
Flat-panel Display Having Concentrated Electron Focusing
The FED of
A spacer system may be situated between devices 100 and 42 for resisting external forces exerted on the FED and for maintaining a relatively uniform spacing between devices 100 and 42. Unlike the displays of
Electron-emitting device, or faceplate structure, 100 is formed with faceplate 50 and a group of layers and regions 102 situated over the interior faceplate surface. Layers/regions 102 include a lower electrically non-insulating region, dielectric layer 72, control electrodes 74, electron-emissive regions 54 arranged in generally straight rows and columns, and electron-focusing system 76.
The lower non-insulating region lies on backplate 50 and includes a group of emitter electrodes 104 extending generally parallel to one another in the column direction. The lower non-insulating region also includes an electrically resistive layer which lies on emitter electrodes 104 and, depending on its shape, may extend down to backplate 50 in the spaces between electrodes 104. The resistive layer is, for simplicity, not explicitly indicated in any of
Each electron-emissive region 54 in the FED of
Each row of electron-emissive regions 54 consists of electron-emissive portions 54C alternating with electron-emissive portions 54D. Each column of regions 54 consists of a column of portions 54C and an adjoining column of portions 54D. The columns of regions 54 are normally spaced largely uniformly apart from one another. The same applies to the rows of regions 54.
Electron-emissive portions 54C and 54D can be configured laterally in various ways. Portions 54C are normally of largely the same size and have largely the same orientation and lateral shape. Portions 54D are likewise of largely the same size and of largely the same orientation and lateral shape. Also, portions 54D are typically of largely the same size, orientation, and lateral shape as portions 54C. Portions 54C and 54D are typically largely symmetrical about their centerlines (not shown) in both the row and column directions. In particular, portions 54C and 54D are typically laterally shaped generally as rectangles. Each rectangle is usually of greater dimension in the column direction than in the row direction.
More generally, portions 54C and 54D of each electron-emissive region 54 are normally configured to be largely mirror images of each other relative to the column direction. As such, portions 54C and 54D of each region 54 may be asymmetrical about their centerlines in the column direction. However, portions 54C and 54D of region 54 are still typically largely symmetrical about their centerlines in the row direction. The layout of
The center-to-center spacing between portions 54C and 54D of each electron-emissive region 54 in the row direction is largely the same for all regions 54. This center-to-center spacing is indicated as item SER in
As in the displays of
A group of main control openings 84C and 84D extend through main control portions 80 of control electrodes 74 respectively above electron-emissive portions 54C and 54D. The pair of main control openings 84C and 84D situated respectively above portions 54C and 54D of each electron-emissive region 54 are laterally separated in the row direction. Electron-emissive elements 78 of each portion 54C or 54D are exposed to enclosure 44 through openings (not explicitly shown) in gate portion 82 of associated electrode 74 at the bottom of corresponding opening 84C or 84D. The size, orientation, and lateral shape of each portion 54C or 54D is defined by overlying opening 84C or 84D.
Portions 54C and 54D of each electron-emissive region 54 overlie one emitter electrode 104 and have a pair of main control openings 84C and 84D extending through main control portion 80 of one control electrode 74. Hence, portions 54C and 54D of each region 54 are controlled together. Provided that portions 54C and 54D of each region 54 are both operative, both of portions 54C and 54D in that region 54 normally emit electrons substantially simultaneously whenever that region 54 emits electrons. Each region 54 may be deemed to include the underlying part of associated emitter electrode 104 and the overlying part of associated gate portion 82.
Electron-focusing system 76 is again situated on dielectric layer 72 and extends over control electrodes 74. A suitable focus potential is again applied to system 76 from an appropriate voltage source (not shown).
A group of focus openings 86C and 86D extend through electron-focusing system 76 down to control electrodes 74. Each focus opening 86C or 86D is located above a corresponding different one of electron-emissive portions 54C or 54D so as to fully expose that portion 54C or 54D. As viewed perpendicular to backplate 50, the lateral boundary of each portion 54C or 54D is preferably situated fully within the lateral boundary of corresponding opening 86C or 86D. Electrons emitted by each portion 54C or 54D pass through overlying opening 86C or 86D on their way to light-emitting device 42. System 76 is normally configured so that the material carrying the focus potential extends from the tops of openings 86C and 86D at least partway down into each of them.
Analogous to electron-emissive portions 54C and 54D, focus openings 86C and 86D can be configured laterally in various ways. Openings 86C are typically of largely the same size and of largely the same lateral orientation and shape. Openings 86D are likewise typically of largely the same size and of largely the same lateral orientation and shape. Also, openings 86D are typically of largely the same size, lateral orientation, and lateral shape as openings 86C. Openings 86C and 86D are typically largely symmetrical about their centerlines (not shown) in both the row and column directions. In particular, openings 86C and 86D are typically laterally shaped generally as rectangles. Each rectangle is usually of considerably greater dimension in the column direction than in the row direction.
Let a “pair” of focus openings 86C and 86D here mean two directly adjacent openings 86C and 86D that respectively expose portions 54C and 54D of an electron-emissive region 54. In general, openings 86C and 86D in each focus-opening pair are normally configured to be largely mirror images of each other relative to the column direction. As a result, openings 86C and 86D in each pair may be asymmetrical about their centerlines in the column direction. Openings 86C and 86D are, however, still typically largely symmetrical about their centerlines in the row direction. Openings 86C and 86D of each pair are typically configured in this mirror-image arrangement when portions 54C and 54D of each region 54 are configured, as described above, in a corresponding mirror-image arrangement relative to the column direction. The layout of
The center-to-center spacing between focus openings 86C and 86D of each pair in the row direction is largely the same for all the pairs of openings 86C and 86D.
Center-to-center spacing SER between portions 54C and 54D of each electron-emissive region 54 is, in accordance with the invention, greater than center-to-center spacing SFR between the pair of focus openings 86C and 86D respectively overlying portions 54C and 54D of that region 54. In other words, portions 54C and 54D of each region 54 are at a greater center-to-center spacing than the pair of overlying openings 86C and 86D. As viewed in the column direction, portions 54C and 54D of each region 54 are thus laterally closer, on the average, to the most remote sides of that pair of openings 86C and 86D than to their closest sides. Due to the focus potential applied to electron focusing system 76, the electrons emitted by portions 54C and 54D of each region 54 are diverted in such a way as to converge.
More particularly, let the row direction to the right in
In one of the two remaining convergence scenarios, the electrons emitted by portion 54C of each electron-emissive region 54 are diverted slightly in the negative row direction. The electrons emitted from portion 54D of that region 54 are diverted slightly more in the negative row direction so as to converge with the electrons emitted from portion 54C of that region 54. The last convergence scenario is the inverse of the second-mentioned convergence scenario in which electrons emitted from portions 54C and 54D of each region 54 converge after being diverted in the positive row direction.
Regardless of which of the three convergence scenarios arises, configuring focus openings 86C and 86D relative to portions 54C and 54D in the preceding manner causes electron-focusing system 76 to function like a converging lens. More particularly, openings 86C and 86D of each pair act like individual converging lenses which converge at largely the same location.
Each electron-emissive portion 54C and overlying focus opening 86C are at a center-to-center offset spacing dEFRL in the row direction. Offset spacing dEFRL is positive when the center of that portion 54C is farther (more distant) in the negative column direction (more to the left in
Offset spacings dEFRL and dEFRR are typically both positive. In that case, the first-mentioned convergence scenario arises in which electrons emitted by portion 54C of each electron-emissive region 54 are diverted slightly in the positive row direction to converge with electrons which are emitted by portion 54D of that region 54 and are diverted slightly in the negative row direction. Spacings dEFRL and dEFRR are preferably positive and largely equal. Electrons emitted by portions 54C and 54D of each region 54 then converge on a location which, as viewed perpendicular to backplate 50, is largely centered between portions 54C and 54D of that region 54.
Referring to
The condition that offset spacings dEFRL and dEFRR be positive and largely equal can be replaced by the condition that center-to-center spacings SEFRL and SEFRR be largely the same and greater than center-to-center focus spacing SFR. Accordingly, electrons emitted by portions 54C and 54D of each electron-emissive region 54 converge in a generally symmetrical manner at a location directly above the composite center of portions 54C and 54D of that region 54.
Light-emitting device 42 here consists of backplate 60, light-emissive regions 64, black matrix 66, and light-reflective anode layer 88 configured and operable as described above in connection with the displays of
Subject to changes that arise from implementing each electron-emissive region 54 as portions 54C and 54D, the FED of
By concentrating the electron focusing in the preceding way, the average distance between electron-emitting device 100 and light-emitting device 42 can be increased. This permits the electrical potential applied to anode layer 88 to be increased. By operating at a higher anode potential, the display of
The display of
Also, the layout of
Flat-panel Display Having Focus-opening Offsets in Row and Column Directions
The FED of
As with primary electron-emissive portions 54C and 54D, each of additional electron-emissive portions 54E and 54F is formed with multiple electron-emissive elements situated largely in openings extending through dielectric layer 72. A group of additional main control openings (not shown here) extend through main control portions 80 of control electrode 74 respectively above additional portions 54E and 54F. Electron-emissive elements 78 of each of portions 54E and 54F are exposed to enclosure 44 through openings (likewise not shown) in gate portion 82 of associated electrode 74 at the bottom of the corresponding main control opening. The size, orientation, and lateral shape of each portion 54E or 54F is defined by the overlying main control opening. Hence, portions 54E and 54F are structured and organized largely the same as portions 54C and 54D.
Portions 54C-54F of each electron-emissive region in the FED of
Portions 54C and 54E of each electron-emissive region are situated in a line extending in the column, or further, direction and are laterally separated in the column direction. Portions 54D and 54F of each region 54 are situated in another line extending in the column direction and thus extend parallel to the line formed with portions 54C and 54E of that region 54. Portions 54D and 54F of each region 54 are laterally separated in the column direction by largely the same spacing as portions 54C and 54E of that region 54.
Electron-emissive portions 54C-54F are configured laterally in generally the manner described above for portions 54C and 54D in the FED of
The presence of additional electron-emissive portions 54E and 54F may impose further constraints on the lateral configurations of primary electron-emissive portions 54C and 54D. For instance, portions 54E and 54F of each electron-emissive region 54 are normally respectively mirror images of portions 54C and 54D in that region 54. Consequently, portions 54C-54F of each region 54 are normally in a mirror-image arrangement in both the row and column directions. The layout of
In light of the preceding symmetry, the center-to-center spacing between additional portions 54E and 54F of each electron-emissive region 54 in the row direction is largely the same for all regions 54 and largely equals spacing SER, the center-to-center spacing between primary portions 54C and 54D of each region 54 in the row direction. The center-to-center spacing between portions 54C and 54E of each region 54 in the column direction is largely the same for all regions 54. This center-to-center spacing is indicated as item SEC in FIG. 16. The center-to-center spacing between portions 54D and 54F of each region 54 in the column direction is likewise largely the same for all regions 54 and largely equals spacing SEC.
A group of additional focus openings 86E and 86F extend through electron-focusing system 76 down to control electrodes 74 in the FED of
Analogous to electron-emissive portions 54C-54F, focus openings 86C-86F are configured laterally in generally the manner described above for openings 86C and 86D in the FED of
With focus openings 86C and 86D of each focus-opening quartet normally being configured to be largely mirror images of each other relative to the column direction, focus openings 86E and 86F of each quartet are likewise normally configured to be largely mirror images of each other relative to the column direction. As with openings 86E and 86D of each quartet, openings 86E and 86F of each quartet may be asymmetrical about their centerlines (not shown) in the column direction. Openings 86E and 86F of each quartet are, however, normally largely symmetrical about their centerlines (not shown) in the row direction.
The presence of additional focus openings 86E and 86F may impose further constraints on the lateral configurations of focus openings 86C-86F. For instance, additional openings 86E and 86F of each quartet are normally respectively mirror images of primary openings 86C and 86D of that quartet. Accordingly, openings 86C-86F of each quartet are normally in a mirror-image arrangement in both the row and column directions. Openings 86C-86F are normally in such an orthogonal-direction mirror-image arrangement when portions 54C-54F of each electron-emissive region 54 are in a corresponding orthogonal-direction mirror-image arrangement. The layout of
The center-to-center spacing between additional focus openings 86E and 86F of each quartet in the row direction is largely the same for all the quartets of focus openings 86C-86F and is largely equal to spacing SFR, the center-to-center spacing between primary focus openings 86C and 86D of each quartet. The center-to-center spacing between openings 86C and 86E of each quartet of openings 86c-86F in the column direction is largely the same for all the focus-opening quartets.
As
Electrons emitted by portion 54D of each electron-emissive region 54 can converge with electrons emitted by portion 54C of that region 54 according to any of the three convergence scenarios described above in connection with the FED of
The manner in which electrons emitted by portions 54C-54F of each electron-emissive region 54 are diverted by electron-focusing system 76 so as to converge is determined, for the row direction, by the factors largely presented above in connection with the FED of
Each electron-emissive portion 54C or 54D and overlying focus opening 86C or 86D are largely at a center-to-center offset spacing dEFCT in the column direction. Each electron-emissive portion 54E or 54F and overlying focus opening 86E or 86F are largely at a center-to-center offset spacing dEFCB in the column direction. Let the column direction toward the top in
Offset spacings dEFRL, dEFRR, dEFCT, and dEFCB are typically all positive. In that case, electrons emitted by portions 54C and 54E of each electron-emissive region 54 are diverted slightly in the positive row direction to converge with electrons which are emitted by portions 54D and 54F of that region 54 and diverted slightly in the negative row direction. Also, electrons emitted by portions 54C and 54D of each region 54 are diverted slightly in the negative column direction to converge with electrons which are emitted by portions 54E and 54F of that region 54 and diverted slightly in the positive column direction.
Row direction offset spacings dEFRL and dEFRR are preferably largely equal. Column direction offset spacings dEFCT and dEFCB are also preferably largely equal. Electrons emitted by portions 54C-54F of each electron-emissive region 54 are then diverted in such a manner as to converge on an overlying position which, as viewed perpendicular to backplate 50, is largely centered between portions 54C-54F of that region 54.
Portion 54E of each electron-emissive region 54 and focus opening 86F overlying portion 54F of that region 54 are at largely the same center-to-center spacing SEFRR in the row direction as portion 54C of that region 54 and focus opening 86D overlying portion 54D of that region 54. Portion 54F of each region 54 and focus opening 86E overlying portion 54E of that region 54 are similarly at largely the same center-to-center spacing SEFRL in the row direction as portion 54D of that region 54 and focus opening 86C overlying portion 54C of that region 54. Portion 54C or 54D of each region 54 and opening 86E or 86F overlying portion 54E or 54F of that region 54 are largely at a center-to-center spacing SEFCT in the column direction. Portion 54E or 54F of each region 54 and opening 86C or 86D overlying portions 54C or 54D of that region 54 are largely at a center-to-center spacing SEFCB in the column direction.
The condition that both of row-direction offset spacings dEFRL and dEFRR be positive is again equivalent to the condition that each of row-direction center-to-center spacings SEFRL and SEFRR be greater than row-direction center-to-center focus spacing SFR. The condition that both of column-direction offset spacings SEFCT and dEFCB be positive is equivalent to the condition that each of column-direction center-to-center spacings SEFCT and SEFCB be greater than column-direction center-to-center focus spacing SFC. With both of these conditions being met, electrons emitted by portions 54C-54F of each electron-emissive region 54 converge above that region 54 at a location which, as viewed perpendicular to backplate 50, is generally located within the rectangle defined by the centers of portions 54C-54F of that region 54.
As in the FED of
The FED of
Focus openings 86C-86F of each focus-opening quartet in the FED of
As indicated in
Due to the focus potential applied to electron-focusing system 76, the electrons emitted by portions 54C and 54D of each electron-emissive region 54 are diverted slightly in the positive column direction. The electrons emitted by portions 54E and 54F of each region 54 are diverted slightly in the negative column direction and thus away from the electrons emitted by portions 54C and 54D of that region 54. In other words, the electrons emitted by portions 54E and 54F of each region 54 diverge from the electrons emitted by portions 54C and 54D of that region 54. This flattens the column-direction profile of the intensity at which electrons emitted by each region 54 strike oppositely situated light-emissive region 64. At the same time, the FED of
By flattening the column-direction profile of the intensity at which electrons emitted by each region 54 strike oppositely situated light-emissive region 64, phenomena that cause undesired electron deflections in the row direction have less damaging effect on the light provided by regions 64. For example, spacer walls situated in the active portion of enclosure 44 and extending in the row direction often cause undesired electron deflections in the column direction. The damaging effect that might result from undesired column-direction electron deflection caused by such spacer walls is significantly reduced in the FED of
Each light-emissive region 64 is situated largely opposite corresponding electron-emissive region 54 in the FED of
The FED employing light-emitting device 110 contains a light-emitting device such as device 42 of
Electron-emitting device 110 is configured the same as electron-emitting device 100 in the FED of
The FED employing electron-emitting device 112 contains a light-emitting device such as device 42 of
Electron-emitting device 112 is configured the same as electron-emitting device 100 in the FED of
Focus Structure, Display Fabrication, and Variations
Base focusing structure 120 consists of electrically non-conductive material, i.e., electrically insulating and/or electrically resistive material.
Focus coating 122 lies on top of base focusing structure 120 and extends partway down the sidewalls of structure 120 into the focus openings such as focus opening 86 illustrated in FIG. 21. Focus coating 122 can extend substantially all the way down the sidewalls of structure 120 provided that coating 122 is electrically insulated from control electrodes 74. Coating 122 consists of electrically non-insulating material, normally electrically conductive material such as metal. In any event, coating 120 is of lower average electrically resistivity, normally considerably lower average electrically resistivity, than structure 120. The focus potential is provided to coating 122.
Each focus opening is laterally separated from each other focus opening by at least the material of focus coating 122. Normally, the material of base focusing structure 120 also laterally separates each focus opening from each other focus opening. Nonetheless, electron-focusing system 76 can be configured so that certain of the focus openings extend through coating 122 at laterally separated locations but are connected together in structure 120. Since coating 122 carries the focus potential which, in combination with the spacing between each focus opening and corresponding electron-emissive region 54 or electron-emissive portion 54A, 54B, 54C, 54D, 54E, or 54F, determines the electron focusing, the interconnection of focus openings in structure 120 is not significant to the present invention.
Each of the present flat-panel CRT displays is fabricated in generally the following manner. Light-emitting device 42 is fabricated separately from electron-emitting device 40, 100, 110, or 112. When spacer walls 46 are employed in the flat-panel display, they are mounted on device 42 or on device 40, 100, 110, or 112. Device 42 is hermetically sealed through the above-mentioned outer wall in such a way that the assembled, sealed display is at a very low internal pressure, typically no more than approximately 10−6 torr.
The fabrication of electron-emitting device 40, 100, 110, or 112 involves forming lower non-insulating region 70 on backplate 50. In so doing, the resistive layer is formed over emitter electrodes 104. Dielectric layer 72 is then deposited on top of the resultant structure. Control electrodes 74, electron-emissive elements 54, and (when present) insulating layer 124 are subsequently formed according to any of a number of process sequences. Base focusing structure 120 is formed on top of the structure in the desired pattern for electron-focusing system 76. Finally, focus coating 122 is deposited on structure 120. Getter material (not shown) may be provided at various locations in device 40, 100, 110, or 112.
Fabrication of light-emitting device 42 involves forming black matrix 66 on faceplate 60. Light-emissive material, typically phosphor, is then introduced into the openings in matrix 66 to create light-emissive region 64. Light-reflective anode layer 88 is subsequently deposited on top of regions 64 and matrix 66. Getter material may be provided at various locations in device 42.
Directional terms such as “lateral”, “above”, and “below” have been employed in describing the present invention to establish a frame of reference by which the reader can more easily understand how the various parts of the invention fit together. In actual practice, the components of a flat-panel CRT display may be situated at orientations different from that implied by the directional terms used here. Inasmuch as directional terms are used for convenience to facilitate the description, the invention encompasses implementations in which the orientations differ from those strictly covered by the directional terms employed here.
The terms “row” and “column” are arbitrary relative to each other and can be reversed. Also, taking note of the fact that lines of an image are typically generated in what is now termed the row direction, control electrodes 74 and emitter electrodes 104 of lower non-insulating region 70 can be rotated one-quarter turn so that control electrodes 74 extend in what is now termed the row direction while emitter electrodes 104 extend in what is now termed the column direction.
While the invention has been described with reference to particular embodiments, this description is solely for the purpose of illustration and is not to be construed as limiting the scope of the invention claimed below. The spacer system can have spacers of shapes other than relatively flat walls. Examples include posts and combinations of flat walls such as crosses and, as viewed vertically, patterns in the shape of an “L”, a “T”, or an “H”.Field emission includes the phenomenon generally termed surface conduction emission.
Electron-focusing system 76 extends a significant distance above electron-emissive regions 54 in the examples presented above such that each focus opening 86 is located substantially fully above its region 54. Alternatively, system 76 can be configured to be in nearly the same plane as regions 54. In that case, each opening 86 may only partially overlie associated region 54. Electrons emitted by that region 54 then pass through only part of associated opening 76. The same applies to how focus openings 86A-86F are respectively situated relative to electron-emissive portions 54A-54F. Various modifications and applications may thus be made by those skilled in the art without departing from the true scope and spirit of the invention as defined in the appended claims.
| Number | Name | Date | Kind |
|---|---|---|---|
| 5374868 | Tjaden et al. | Dec 1994 | A |
| 5543683 | Haven et al. | Aug 1996 | A |
| 5569975 | Taylor et al. | Oct 1996 | A |
| 5574333 | Clerc | Nov 1996 | A |
| 5589728 | Levine et al. | Dec 1996 | A |
| 5621272 | Levine et al. | Apr 1997 | A |
| 5631518 | Barker | May 1997 | A |
| 5650690 | Haven | Jul 1997 | A |
| 5672933 | Wilson et al. | Sep 1997 | A |
| 5686782 | Hecker, Jr. et al. | Nov 1997 | A |
| 5838097 | Kasanuki et al. | Nov 1998 | A |
| 5859502 | Spindt et al. | Jan 1999 | A |
| 5898266 | Spindt et al. | Apr 1999 | A |
| 5990614 | Spindt | Nov 1999 | A |
| 5998923 | Jager | Dec 1999 | A |
| 6002199 | Spindt et al. | Dec 1999 | A |
| 6013974 | Haven et al. | Jan 2000 | A |
| 6049165 | Spindt et al. | Apr 2000 | A |
| 6064157 | Spindt et al. | May 2000 | A |
| 6107728 | Spindt et al. | Aug 2000 | A |
| 6107731 | Spindt et al. | Aug 2000 | A |
| 6242865 | Zimlich | Jun 2001 | B1 |
| 6320310 | Imai et al. | Nov 2001 | B1 |
| 6437503 | Konuma | Aug 2002 | B1 |
| 6472813 | Mitsutake et al. | Oct 2002 | B2 |
| Number | Date | Country |
|---|---|---|
| WO 0002081 | Jan 2000 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20030062823 A1 | Apr 2003 | US |
