WO2000021111A1

WO2000021111A1 - Flat panel display and method of making

Info

Publication number: WO2000021111A1
Application number: PCT/US1999/021359
Authority: WO
Inventors: John Glesener
Original assignee: Litton Systems, Inc.
Priority date: 1998-10-01
Filing date: 1999-09-14
Publication date: 2000-04-13

Abstract

A FED type of flat panel display device (10) includes an array of cold-cathode electron emitters (24) and a display screen (34/34a) receiving electrons (26') in response to emission of electrons from the electron emitters (24) to produce light forming an image. The display device (10) includes a microchannel plate (28) interposed between the array of electron emitters (24) and the display screen (34/34a), which microchannel plate (28) receives electrons (26) from the emitters (24) and responsively provides a greatly amplified shower of secondary emission electrons (26'). A brighter image may result from the display device (10), or the device may be operated at lower voltages while providing an image of brigthness comparable to conventional display panels of the FED type.

Description

FLAT PANEL DISPLAY AND METHOD OF MAKING

Background of the Invention Field of the Invention

The present invention is in the field of image displays. More particularly, the present invention relates to a display device of the flat-panel variety. A flat panel display device according to the present invention includes a gain block functional element, which includes a microchannel plate of unique construction. Further, the present invention relates to a method of making such a flat panel display device.

Related Technology Flat panel display devices find wide application today, for example, in laptop and other computer devices, in aircraft displays, and in consumer appliances which need to have a visual image display function. A particular type of flat panel display is known as the field emission display (FED) type, and has an array of addressable electron emitters in juxtaposition to a phosphor screen. Color versions of this FED type of display device include an addressable gate structure which allows selection of particular color phosphors for illumination.

More particularly, Flat panel FED's consist of an X-Y (i.e., orthographically) matrix of electrically-addressable cold-cathode field-emission devices, opposing a phosphor-coated transparent plate; in which the volume of space between the emission devices and the phosphor-coated plate is evacuated. When an emitter in the matrix has been addressed and activated, electrons are accelerated from one or more of the cold cathode devices, dependent upon the number of such emitters activated, and toward the phosphor-coated transparent plate. This plate serves an anode, and has a positive voltage relative to the emitters in the array. The phosphor on the transparent plate is induced into cathodoluminescence by the electrons from the emitters, which bombard this phosphor coating by the same mechanism that is observed in a conventional cathode ray tube (CRT). This luminescence of the phosphor serves as the emissive light source seen by an observer of such a flat panel display device. One particular type of electron emitter used in such FED display devices is known as a Spindt emitter. Several US patents are issued to C. Spindt which relate to this type of electron emitter. Additionally, commercially available displays of this type are know from Micron Display, a division of Micron Technology, Inc.

Summary of the Invention

Persistent problems with conventional flat panel display devices of the type generally described above are in one respect is that the display device has a luminosity that is lower than desired; or in another respect, the turn-on voltage for useful electron emission from the cold-cathode emitters is high enough such that in order to accommodate this high turn-on or driving voltage for the cold cathode that costly electronic components are required for the circuits to drive the conventional flat panel displays. In other words because of this first problem mentioned above, if, for example, a conventional flat panel display is used for a television or a computer monitor the image provided by the display device would best be viewed in a darkened room. If attempts are made to use such display devices in a brightly lighted room or outdoors in day time, then difficulties will be encountered in seeing the image. This is the case simply because the conventional FED flat panel display device is unable to generate a sufficient light output. Because of the second problem explained above, the costs of conventional flat panel displays are much more than is desired because of the higher cost of the electronic circuits to drive these displays.

Accordingly, it is desirable and is an object for this invention to provide a FED type of flat panel display device that has a much higher light output. A further object of the present invention is to provide a method of making such a FED type of flat panel display device.

Still another object for this invention is to provide an FED type of flat panel display which is capable of generating a light output comparable to that of a conventional FED flat panel display device but does so while requiring a much lower cold-cathode electron emitter turn-on voltage than the conventional device.

Accordingly the present invention provides according to a particularly preferred exemplary embodiment of the invention, a flat panel display device comprising: an array of cold-cathode electron emitters, a display screen juxtaposed to the array of electron emitters and responsive to electron flux to provide localized emission of light, and a microchannel plate interposed between the array of electron emitters and the display screen to receive electron emissions from the former and provide a respective amplified shower of secondary emission electrons to the latter when the proper voltages required for MCP amplification are externally applied to the device.

Also, the present invention provides a method of making such an FED flat panel display device.

In view of the above, it will be apparent that an advantage of the present invention resides in the provision of an FED type of flat panel display device that is capable of providing an image of much greater luminosity than conventional FED flat panel displays.

An advantage of the present invention resides in the provision of a flat panel display device with sufficient luminosity that the image provided by the display is visible in a brightly lighted room or in daytime outside.

Another advantage of the present invention results from the fact that it can be operated at a substantially lower voltage for the cold-cathode emitters than is possible with the conventional flat panel displays of this type, and while still producing a comparable light output. A safer display device results, that can be operated with less expensive cathode display driver electronic circuits, and also has a longer service life.

These and additional objects and advantages of the present invention will be apparent from a reading of the present detailed description of a single particularly preferred exemplary embodiment of the present invention, taken in conjunction with the appended drawing Figures, in which the same reference numeral refers to the same feature, or to features which are analogous in structure or function to one another.

Description of the Drawing Figures

Figure 1 provides a schematic perspective view of a flat panel display device embodying the present invention. Figure 2 is a greatly enlarged cross sectional view taken at line 2-2 of Figure 1. Detailed Description of a Preferred Exemplary Embodiment of the Invention

Viewing Figure 1, a flat panel display device 10 includes a body 12 which is generally a flattened prismatic solid. The body 12 has a width "W", and a height "H", both of which are several multiples of the thickness "t" of the body. At the front or image face 14 of the device 10, the body 12 includes a transparent plate 16, which may be formed of glass, although the invention is not so limited. A rear or back-plane plate

18 of the device 10 may be opaque, and the plates 16 and 18 are spaced from one another and sealingly united into a unitary structure by peripheral wall portions 20, only two of which are seen in Figure 1.

Along two sides of the device 10, the body 12 carries a respective one of a pair of multi-contact edge connectors, each indicated with the arrowed numeral 22. The edge connectors 22 are merely exemplary, and other types and configurations of connectors may be used with the present invention. However, it is seen in Figure 1 , that each of the connectors 22 provides a great multitude of electrical contacts 22a arrayed along the length of each of these connectors. Although it is not visible in Figure 1, those ordinarily skilled in the pertinent arts will understand that the connectors 22 may include additional contacts 22a on the side opposite to that seen in Figure 1. Thus, for example, if the display device 10 provides a vertical-by-horizontal resolution of 480-by- 640 pixels, the connector 22 along the vertical side of body 12 (i.e., along the left side of the body 12 as seen in Figure 1) will have 480 contacts 22a, while the connector 22 along the horizontal side of the body 12 (i.e., along the top of the body 12 as seen in Figure 1) will have 640 contacts 22a. These contacts 22a of the connectors 22 provide for X-Y electrical addressing of cold-cathode electron emitters within the device 10, as will be understood by those ordinarily skilled in the pertinent arts, and as is further described below.

Viewing now Figure 2, a greatly enlarged cross sectional view of the device 10 is depicted. This device 10 includes a two dimensional array (seen in only one dimension in the cross section of Figure 2) of cold cathode electron emitters 24, only a portion of which array is illustrated in Figure 1. The cold cathode emitters 24 each include a spike emitter portion 24a, and a respective portion of a control grid 24b, which has a great multitude of respective apertures 24c with which the multitude of spike emitter are individually aligned. Those ordinarily skilled in the pertinent arts will understand that the emitters 24a, or respective grid portions, or both, are individually electrically addressable (i.e., via contacts 22a of the connectors 22) in a row and column fashion) in order to control and effect electron emissions from selected portions of the emitter array 24. These electron emissions will proceed rightwardly in Figure 2, toward an anode, which will be further described. An exemplary electron emission is represented in Figure 2 by arrow 26.

Still viewing Figure 2, it is seen that the device 10 includes a microchannel plate (MCP) 28 disposed so as to receive electron emissions from the array 24. The microchannel plate 28 includes a perforate body 30 fabricated principally of glass, and defining a great multitude of microchannels 32 extending angularly through this body from one face to the other. The microchannels are angulated slightly for a purpose which is well understood in the pertinent art. The microchannel plate 28 carries a pair of opposite conductive electrodes 28a and 28b, exterior electrical connections to which are indicated in Figure 1 with these same reference numerals and an arrowed lead line. The electrodes 28a and 28b define respective openings at the microchannels 32, so that these microchannels are open to receive electrons such as the exemplary emission 26.

Considering the exemplary emission 26, it is seen that the electrons from this emission at least in part are received into microchannels 32 of the microchannel plate 28 which are generally aligned with the location of emitter array 24 which has been activated to produce this electron emission. The electrons 26 cause emission of secondary-emission electrons in microchannel plate 28 so that from the opposite face of this plate issues a greatly increased shower of electrons 26'. The shower of electrons 26' may be one or several orders of magnitude greater in intensity than the electron emission 26. This shower of electrons is driven by an electrostatic field applied between the electrode 28b and a screen electrode, generally indicated with the numeral 34, and which is carried on the inner face of the plate 16 (i.e., the face of this plate opposite to image face 14). The screen electrode 34 has associated with it a layer of phosphor, indicated by the arrowed numeral 34a, and as is well understood in the pertinent arts. Accordingly, the shower of electrons 26' causes a spot of light 36 to be illuminated on the phosphor of electrode 34. As is illustrated in Figure 2, this light is visible through plate 16. Accordingly, by selective application of control voltages to the spike emitters 24a and/or grid 24b, the location of light emissions from the image face 14 of the device 10 is controllable. This allows device 10 to be used as a display, as will be well understood by those ordinarily skilled in the pertinent arts. However, in contrast to the conventional FED type of flat panel displays, display 10 has an electron gain between the emitters 24 and the display electrode 34 which may provide several orders of magnitude of electron amplification. The resulting image created by the display device 10 is accordingly much brighter and more intense (and is, therefor, much more easily viewed in bright light conditions), than are conventional display devices of the FED type. Alternatively, the electron emitters can be operated at a lower voltage to achieve a light output comparable to a conventional FED flat panel display. This lower voltage operation for a display panel according to the invention can increase the service life of the display panel. Furthermore, the device can be operated with less costly electronic components in the voltage supply for the display panel, since, as described above, lower operating voltages will suffice for the inventive display panel.

While the present invention has been depicted, described, and is defined by reference to a particularly preferred embodiment of the invention, such reference does not imply a limitation on the invention, and no such limitation is to be inferred. The invention is capable of considerable modification, alteration, and equivalents in form and function, as will occur to those ordinarily skilled in the pertinent arts. The depicted and described preferred embodiment of the invention is exemplary only, and thus, is not exhaustive of the scope of the invention. Consequently, the invention is intended to be limited only by the spirit and scope of the appended claims, giving full cognizance to equivalents in all respects.

Claims

I Claim:

1. A flat panel display device comprising: an array of cold-cathode electron emitters, a display screen juxtaposed to said array of electron emitters and responsive to electron flux to provide localized emission of light, and a microchannel plate interposed between said array of electron emitters and said display screen to receive electron emissions from the former and provide a respective amplified shower of secondary emission electrons to the latter.

2. The flat panel display device of Claim 1 wherein said device includes a body having a front plate and a back plate spaced apart to define an evacuated cavity therebetween, and said microchannel plate is disposed within said evacuated chamber between said cold-cathode emitters and said display screen.

3. The flat panel display device of Claim 2 wherein said back plate carries said array of cold-cathode electron emitters, and said front plate carries said display screen.

4. The flat panel display device of Claim 1 wherein said device has a rectangular configuration viewed from an image output face of the device, and said microchannel plate has a substantially matching rectangular configuration.

5. A method of making a flat panel display device, said method comprising steps of: providing a flat panel housing having a back plate, a transparent front plate, an array of cold-cathode electron emitters, and a display screen visible through the front plate; interposing a microchannel plate between the array of electron emitters and the display screen; and utilizing the microchannel plate to amplify electron flux produced at said array of electron emitters and to responsively provide an amplified flux of secondary emission electrons for bombarding said display screen to produce light.

6. A method of operating a flat panel display device having an array of elecfron emitters and a display screen receiving electrons in response to electron emission at said array of electron emitters to produce visible light, said method comprising the steps of: providing a microchannel plate interposed between said array of election emitters and said display screen; utilizing said microchannel plate to receive electrons from said array of electron emitters and to responsively provide a shower of secondary emission electrons; and utilizing said shower of secondary emission elecfrons to bombard said display screen and to cause the responsive production of light.