EP0446041A2 - Elektronisches Fluoreszenzanzeigesystem - Google Patents

Elektronisches Fluoreszenzanzeigesystem Download PDF

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Publication number
EP0446041A2
EP0446041A2 EP91301882A EP91301882A EP0446041A2 EP 0446041 A2 EP0446041 A2 EP 0446041A2 EP 91301882 A EP91301882 A EP 91301882A EP 91301882 A EP91301882 A EP 91301882A EP 0446041 A2 EP0446041 A2 EP 0446041A2
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EP
European Patent Office
Prior art keywords
cathode
electrodes
anode
grid electrodes
scanning
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP91301882A
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English (en)
French (fr)
Other versions
EP0446041A3 (en
Inventor
Ge Shichao
Victor Lam
Huang Xi
Jin Weicheng
Ruan Shiping
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hangzhou University
Panocorp Display Systems
Original Assignee
Hangzhou University
Panocorp Display Systems
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Priority claimed from CN90101232.7A external-priority patent/CN1026943C/zh
Application filed by Hangzhou University, Panocorp Display Systems filed Critical Hangzhou University
Publication of EP0446041A2 publication Critical patent/EP0446041A2/de
Publication of EP0446041A3 publication Critical patent/EP0446041A3/en
Withdrawn legal-status Critical Current

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J31/00—Cathode ray tubes; Electron beam tubes
    • H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
    • H01J31/10—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes
    • H01J31/12—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes with luminescent screen
    • H01J31/15—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes with luminescent screen with ray or beam selectively directed to luminescent anode segments
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
    • H01J1/02—Main electrodes
    • H01J1/13—Solid thermionic cathodes
    • H01J1/15—Cathodes heated directly by an electric current
    • H01J1/18—Supports; Vibration-damping arrangements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
    • H01J29/02—Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
    • H01J29/028—Mounting or supporting arrangements for flat panel cathode ray tubes, e.g. spacers particularly relating to electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J31/00—Cathode ray tubes; Electron beam tubes
    • H01J31/08—Cathode ray tubes; Electron beam tubes having a screen on or from which an image or pattern is formed, picked up, converted, or stored
    • H01J31/10—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes
    • H01J31/12—Image or pattern display tubes, i.e. having electrical input and optical output; Flying-spot tubes for scanning purposes with luminescent screen
    • H01J31/123—Flat display tubes
    • H01J31/125—Flat display tubes provided with control means permitting the electron beam to reach selected parts of the screen, e.g. digital selection
    • H01J31/126—Flat display tubes provided with control means permitting the electron beam to reach selected parts of the screen, e.g. digital selection using line sources
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
    • G09G2310/00—Command of the display device
    • G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
    • G09G2310/0235—Field-sequential colour display

Definitions

  • This invention relates in general to electronic fluorescent display devices and in particular, to a low voltage cathodoluminescent device particularly useful for flat mosaic large-screen and ultra-large screen full color hang-on-wall type displays.
  • Cathode ray tubes have been used for display purposes in general, such as in conventional television systems.
  • the conventional CRT systems are bulky primarily because depth is necessary for an electron gun and an electron deflection system.
  • U.S. Patent No. 3,935,500 to Oess et al. for example, a flat CRT system is proposed where a deflection control structure is employed between a number of cathodes and anodes.
  • the structure has a number of holes through which electron beams may pass with a set of X-Y deflection electrodes associated with each hole.
  • the deflection control structure defined by Oess et al. is commonly known as a mesh-type structure. While the mesh-type structure is easy to manufacture, such structures are expensive to make, particularly in the case of large structures.
  • Mosaic large-screen full color displays have been used frequently in public environments such as sports stadiums and exhibition halls.
  • Several types of mosaic full color large-screen displays have been in use or proposed.
  • the flat matrix CRT its anode voltage is as high as 8 kilovolts or higher and has low phosphor dot density. It is mainly used in the outdoor environment. Because of the above-described characteristics, it is difficult to construct a thin, high dot density display for use in indoor applications such as for hang-on-wall televisions using the flat matrix CRT.
  • Jumbotron Another conventional system currently used is known as the Jumbotron such as that described in Japanese Patent Publication Nos. 62-150638, 62-52846.
  • the structure of Jumbotron is somewhat similar to the flat matrix CRT described above. Again the anode voltage is as high as 8 kilovolts or above and the display panel at least over 1 inch in thickness. Each anode includes only less than 20 pixels so that it is difficult to construct a high phosphor dot density type display system using the Jumbotron structure.
  • Both the flat matrix CRT and Jumbotron structures are somewhat similar in principle to the flat CRT system described by Oess et al. discussed above. These structures amount to no more than enclosing a number of individually controlled electron guns within a panel, each gun equipped with its own grid electrodes for controlling the X-Y addressing and/or brightness of the display.
  • the control grid electrodes used are in the form of mesh structures. These mesh structures are typically constructed using photo-etching by etching holes in a conductive plate. The electron beams originating from the cathodes of the electron guns then pass through these holes in the mesh structure to reach a phosphor material at the anodes. As noted above, mesh structures are expensive to manufacture and it is difficult to construct large mesh structures.
  • each cathode has its own dedicated mesh structure for controlling the electron beam originating from the cathode. Since the electron beam must go through the hole in the mesh structure, a large number of electrons originating from the cathode will travel not through the hole, but lost to the solid part of the structure to become grid current so that only a small portion of the electrons will be able to escape through the hole and reach the phosphor material at the anode. For this reason the osmotic coefficient, defined as the ratio of the area of the hole to the area of the mesh structure of the cathode, of the above-described devices is quite low.
  • each cathode has its own dedicated mesh structure, in order to avoid mutual interference between adjacent mesh structures, it is necessary to leave sufficient spacing between the mesh structures of adjacent cathodes. For this reason, each display panel in the above-described devices includes less than 20 pixels so that it is difficult to construct a high phosphor dot density type display system using the above-proposed structures.
  • Another conventional mosaic full color large-screen display system is the color vacuum fluorescent display such as that described in Japanese Patent Publication No. 62-52836. It employs a cathode, an anode, and one grid. An auxiliary cathode and light leader are used to increase dot density.
  • the anode voltage used is around 300 volts.
  • the anode and grid are used for X-Y addressing. Since the anode is used in addressing, the anode voltage cannot be higher than 300 volts in order to prevent electrical shorts between anodes.
  • the luminescence of the three primary colors red, blue and green (R, B and G) phosphors are low at voltages such as 300 volts and below. Furthermore, at such voltages, the phosphors have short lifetimes.
  • LCD back lighting liquid crystal displays
  • R, B, G photoarrays so that it is difficult and expensive to manufacture.
  • a large number of lighting sources need to be used behind the display screen and only a small portion of the light from the light sources is transmitted so that it is inefficient.
  • This invention is based on the observation that by using two or more sets of elongated grid electrodes with electrodes in each set overlap those in the other set at pixel dots, the above-described difficulties with conventional systems are alleviated or avoided altogether.
  • the appropriate electrical potentials are applied to the anode, cathode, and a set of grid electrodes, the electrons emitted by the cathode are caused to travel to the anode at the pixel dots for displaying images. Since overlapping elongated grid electrodes are used in place of the conventional mesh structure, the osmotic coefficient is greatly increased. Since the grid electrodes serve to address and/or supply brightness data to a number of pixel dots, the pixel dots can be much closer together than the conventional displays where adequate spacing must be maintained between the adjacent mesh structures of adjacent electron guns.
  • one aspect of the invention is directed towards a cathodoluminescent visual display device having a plurality of pixel dots.
  • the device comprises an anode, luminescent means that emits light in response to electrons, and that is on or adjacent to the anode and the cathode.
  • the device further comprises two or more sets of elongated grid electrodes between the anode and cathode and means for heating the cathode, causing the cathode to emit electrons.
  • the electrodes in each set overlap those in at least one other set at points, wherein the overlapping points define the pixel dots.
  • the device further includes means for applying electrical potentials to the anode, cathode and the two or more sets of grid electrodes, causing the electrons emitted by the cathode to travel to the anode at the pixel dots for displaying images.
  • a first, second and third set of grid electrodes are used which are respectively in the first, second and third planes between the planes of the cathode and anode.
  • Each of at least some grid electrodes in the first set is parallel to and corresponds to a grid electrode in the third set defining a pair of corresponding electrodes.
  • the same electrical potential is applied to the pair of corresponding electrodes to enable more electrons to travel beyond to the second set of grid electrodes and to reach the anodes, thereby increasing the luminescence of the device.
  • the cathode includes one or more filaments, each comprising a center core material and a coating, and two springs connecting each filament to the housing.
  • the springs are made of substantially the same material as the filament center core material, thereby reducing cold terminal effects.
  • a display device includes a housing which has a face plate having an edge and an inside surface inside the housing, and a side plate connected to the face plate at or near the edge to form a portion of the housing.
  • the face plate is made of a transparent material.
  • the device further includes luminescent means on or in the vicinity of set inside surface and in the vicinity of set edge. The luminescent means emits light through the face plate for displaying visual images.
  • the face plate has an outside surface at or near the edge through which light from the luminescent means passes.
  • the outside surface of the face plate is curved and of such a shape that the virtue image of the luminescent means to an observer outside of the housing appears to be at a predetermined fixed location in the side plate to reduce the effects of mosaic slots in mosaic displays constructed using the device.
  • the device is useful in PDP, flat CRT, EL, LCD, EPD, or ECD type.
  • a visual display device comprises an anode, a cathode, a plurality of sets of elongated grid electrodes between the anode and cathode, and housing means holding the anode, cathode and grid electrodes.
  • the anode and cathode are in respectively the anode plane and the cathode plane that are spaced apart.
  • the sets of grid electrodes are each in its respective plane that is different from one another, set planes of the grid electrodes being located between the anode and cathode planes where the first set of grid electrodes closer to the cathode than the anode and the second set of grid electrodes between the first set of electrodes and the anode.
  • the device further comprises a first spacer means between the back plate and the first set of grid electrodes, one or more second spacer means between the first and second sets of grid electrodes and a third spacer means between the anode and the second set of grid electrodes.
  • the first, second and third spacer means are elongated members where the length of the member of at least one of the second spacer means transfers to the lengths of the members of the first and third spacer means.
  • a mosaic visual display device comprises N rows and M columns of display panels, N, M being positive integers.
  • Each panel includes an anode, luminescent means that emits light in response to electrons and that is on or adjacent to the anode and the cathode.
  • Each panel further includes two or more sets of elongated grid electrodes between the anode and cathode, said sets including one set of n scanning electrodes and a set of m data electrodes, n, m being positive integers.
  • the n scanning electrodes and m data electrodes overlap one another at points and define a matrix of n.m pixel dots at the overlapping points, said matrix having n rows.
  • the device further comprises n first drivers, each connected to one of the n scanning electrodes for scanning the n rows of the matrix and N second drivers, each connected to the cathodes of one of the N rows of panels, said first and second drivers in combination scanning all the n.N rows of pixel dots in the device.
  • Fig. 1a is a top view of a flat matrix electronic fluorescent device to illustrate the preferred embodiment of the invention.
  • Fig. 1b is a partially side view and partially cross-sectional view of the device in Fig. 1a.
  • Fig. 1c is a side view of the device in Fig. 1a for a direction perpendicular to the view taken in Fig. 1b.
  • Fig. 2 is a cross-sectional view of a portion of the device in Fig. 1a showing in more detail the internal structure of the device.
  • Figs. 3a, 3b are schematic views of two embodiments of pixel dots and the corresponding addressing and data grid electrodes to illustrate the invention.
  • Fig. 4 is a cross-sectional view of a portion of the device in Fig. 1a showing in more detail the internal construction of the device.
  • Fig. 5a is a cross-sectional view of a portion of a top corner portion of the device in Fig. 1a and of a similar portion of a second device of the same structure as that in Fig. 1a when the two devices are placed together side by side in a mosaic arrangement to illustrate the effectiveness of the invention in reducing the visual effects of mosaic slots.
  • Fig. 5b is a graphical illustration of the feature of the invention in Fig. 5a.
  • Fig. 6a is a schematic scanning circuit diagram of the control circuits for operating a mosaic visual display device having N rows and M columns of the display panels to illustrate the preferred embodiment of the invention.
  • Fig. 6b is a timing diagram to illustrate the operation of the circuit of Fig. 6a.
  • Fig. 7 is a schematic diagram of a mosaic visual display device comprising two rows and three columns of display panels to illustrate the preferred embodiment of the invention.
  • Fig. 8 is a schematic circuit diagram which operates in conjunction with the circuit of Fig. 6a for operating the mosaic visual display device.
  • Fig. 9 is a cross-sectional view of a portion of the device in Fig. 1a to illustrate the preferred embodiment of the invention.
  • Fig. 1a is a top view of a flat electronic fluorescent display device 101 to illustrate the preferred embodiment of the invention.
  • device 101 has twelve rows and twelve columns of pixels. Where a large number of devices such as 101 are placed side by side next to each other in a two-dimensional array, these devices form a mosaic full color full screen display.
  • Figs. 1b, 1c are side views from two different directions of device 101 of Fig. 1a where in Fig. 1b, a portion of the device is shown in cross-section.
  • device 101 includes a direct heating type oxide-coated filament cathode 104, two or three grids 105, anode 107 on which is deposited three primary color phosphor dots 106. While in the preferred embodiment, dots 106 are shown as being present on anode 107, it will be understood that, for the purposes of the invention, the dots may also be adjacent to the anode; such modifications and other arrangements are within the scope of the invention.
  • the cathode grids and anode are housed within a housing comprising a face plate 108 and a back plate 109 connected together by means of a side wall 110 to form a flat panel housing with a chamber therein which is evacuated.
  • Cathode 104, grids 105 and anode 107 are sealed to the housing of this chamber by means of glass frit.
  • the side walls of the vacuum chamber and spacers 111 are used to support and fix the positions of the grid electrodes and to increase the strength of the housing in resisting atmospheric pressure.
  • Exhaust pipe 112 has a getter 113 therein and is protected by a cover 114.
  • the leads (not shown) for connecting the anode, cathodes and grid electrodes to the outside drive circuits are wires or conductive traces on printed circuit board 115.
  • board 115 is glued to the display panel to form a unitary body.
  • Board 115 has connectors 116 for connecting the board electrically to outside devices and screws 117 for mounting device 101 onto a support structure.
  • a DC/AC converter 118 is connected to board 115 for applying a AC voltage for the purpose of heating the cathode filament.
  • a black sealing elastic protective ring 119 is mounted onto the side wall of the device.
  • cathode filament When a rated voltage is applied to cathode filament by means of converter 118, and when the filament is heated to a high temperature, the cathode filament will emit electrons. These electrons are accelerated by means of the potential difference between cathode 104 and grids 105 and will travel to the phosphor dots on the anode which is at a much higher voltage than the cathode. The phosphor will be excited by the electrons to emit red, green or blue light for full color display image.
  • Fig. 2 is a cross-sectional view of a portion of device 111 of Fig. 1a to illustrate in more detail the structure of the device.
  • Direct heating oxide-coated filament cathode includes a metallic core 202 with a coating 203 of electron emitting material.
  • filament 201 emits electrons.
  • device 101 includes three sets of grid electrodes 208 (G3), 209 (G2) and 210 (G1).
  • these three sets of grid electrodes are each made of elongated members such as small gauge alloy wires.
  • the diameter of these wires are relatively small compared to the spacing between the wires so that the osmotic coefficient of these grid electrodes is much higher than that of the mesh structures in conventional mosaic devices; this greatly increases the proportion of electrons emitted by the cathode that will reach the phosphor material on the anode and therefore greatly increases the luminescence of the device.
  • these three sets of electrodes are each located in one of three planes defining a first, second and third plane in which the three sets of electrodes G1, G2, G3 are respectively located.
  • each set of grid electrodes comprises a number of wires arranged parallel to one another where the middle set of electrodes 209 are substantially perpendicular to the electrodes in the remaining two sets 208, 210. As shown in Fig. 2, the electrodes in set 209 are substantially parallel to cathode 201 whereas those in sets 208, 210 are substantially perpendicular to the cathode and to the plane of Fig. 2.
  • One of the three sets of grid electrodes is used for scanning and another set of carrying brightness information (data) for the phosphor. Points at which these two sets of electrodes overlap define the pixel dots of device 101. Obviously, a pixel may include one or more pixel dots.
  • the DC level of the cathode is in the range of 0-60 volts, the anode at 2,000 volts, set 209 of electrodes at voltages in the range of 0-60 volts and sets 208, 210 at voltages between 0-12 volts.
  • the anode is operated at a voltage substantially within the range of 500-3,000 volts.
  • the AC current used to heat the cathode may be supplied at a low voltage such as between 6-8 volts.
  • set 208 may be eliminated from device 101 although the use of set 208 will further increase the luminescence of device 101 for reasons explained below. Since it is possible for electrodes in set 209 to be under lower voltage compared to electrodes in set 210, when this happens and when the electrons travel past set 210 to reach the space between sets 209 and 210, some electrons may become attracted back towards the electrodes in set 210 and becomes grid current, thereby never reaching the phosphor material on the anode. This is caused by the local reverse electrical fields in the space between the electrodes in sets 209 and 210. As shown in Fig.
  • each electrode such as 208′ overlaps electrodes in set 209 at the same pixel dot as a corresponding grid electrode 210′ in set 210, forming a pair of corresponding electrodes.
  • each pair of corresponding electrodes in sets 208, 210 is connected electrically by a wire W so that the pair of corresponding electrodes are at the same electrical potential.
  • an electrode in set 209 is at a low voltage such as 0 volts whereas the corresponding pair 208′, 210′ are at a relatively higher voltage (12 volts)
  • the presence of a higher voltage on electrode 208′ would dilute the effect of the localized reverse electric field which otherwise would be present between such electrode in set 209 and electrode 210′.
  • Such dilution would reduce the tendency of the electrons to double back in the space between set 209 and electrode 210′ and encourages such electron to penetrate the plane of set 209 and continue its travel towards the phosphor on the anode. While only three sets of grid electrodes are shown, it will be obvious that more than three sets of grid electrodes may be used and are within the scope of the invention. While the use of a device without set 208 is not as desirable, using only two sets of small gauge wire grid electrodes still achieves better performance compared to conventional mosaic devices discussed above.
  • the cathode may comprise a number of substantially parallel filaments where each filament emits electrons for one column of pixels such as shown in Fig. 1a.
  • Each filament is connected at two ends to the printed circuit board by means of springs 204 and leads 205.
  • the core 202 of the cathode is usually made of a very fine gauge wire and springs that are available commercially are typically much thicker and difficult to connect to the core 202.
  • conventional springs typically have low resistance and will therefore be heated to a low temperature compared to core 202. The temperature differential between such spring and the end portion of core 202 will cause such end portion of the core to be at the lower temperature, thereby reducing the effectiveness of this portion of the filament in emitting electrons.
  • spring 204 is formed from a continuation of core 202 by simply bending the two ends of core 202 into springs. These springs would permit the cathode to expand or contract without sagging and the tension maintained by these springs in the filament would reduce the amplitude of vibrations. By bending the end portions of core 202 into springs, it is unnecessary to connect the core to a separate spring and also reduces dark areas of the display caused by cold terminal effects discussed above. Springs 205 also serve as the support frame and leads followed onto board 206 and connected through connectors 207 to the system circuit.
  • Grid electrodes in sets 208, 209 and 210 are supported by side walls 211 and spacers to ensure that they have sufficient tension so as to reduce the amplitude of vibrations and the chances of short circuit which may cause damage to the device.
  • such structure of grid electrodes has high osmotic coefficient, causing the display panel to accomplish pulse luminescence above 500,000 cd/m2 when the anode is operated at about 2,000 volts. As discussed further below, this permits full screen scanning and achieves sufficient average luminescence as a full color large screen television.
  • Anode 212 is formed by a continuous transparent layer on the inner surface of face plate 213. On top of the anode is the RGB three primary color phosphor dot array 214. Black insulating strips 215 between the phosphor dots enhance contrast of the display.
  • Figs. 3a, 3b are schematic views of pixels and the associated grid electrodes to illustrate the preferred embodiment of the invention.
  • Fig. 3a illustrates one configuration of pixels.
  • each pixel 301 includes two areas, the top area includes red, green and blue portions and the bottom area includes similar portions.
  • the top area is addressed or scanned by four pairs of corresponding electrodes in sets 208, 210 in Fig. 2.
  • the brightness of the red portion is controlled by the common voltage on the electrodes G2′ connected together.
  • the brightness of the green portion is controlled by the voltage on the electrodes G2 ⁇ and that of the blue portion by G2 ⁇ ′.
  • the four pairs of corresponding electrodes in sets 208 and 210 are connected together as one common set G131 as shown in Fig. 3. Obviously, it is possible for the four pairs of electrodes within G131 not to be connected and for the five electrodes in each of G2′, G2 ⁇ , G2 ⁇ ′ not be connected to increase the resolution of the display.
  • Fig. 3b illustrates an alternative configuration for the makeup of the pixels. Again four pairs of corresponding electrodes in sets 208, 210 of Fig. 2 are connected together to form a common set G131.
  • the G2 electrodes are grouped together in groups of wires, each group connected together in a similar manner for displaying phosphor dot 302.
  • Fig. 4 is a cross-sectional view of a section of the device 101 of Fig. 1.
  • the transparent conductive film 402 forming the anode on face plate 401 may be made of SnO2 or ITO; its resistance is preferably minimized and its transparency maximized.
  • the primary color phosphor dots 403 and black insulating strips 404 are deposited onto the anode.
  • Anode lead 405 separates into two branches at right angles before it is connected to anode 402 to increase the area of contact. These two branches are kept in place by a glass inner wall.
  • a silver material 406 at the contact between lead 405 and film 402 further reduces resistance.
  • Lead 405 passes through exhaust hole 407 and the bottom portion of exhaust pipe 408 and is connected to printed circuit board 409.
  • Glass tube 410 surrounds lead 405 and prevents the high voltage applied to the anode to affect the grids and the uniformity of the display.
  • the back glass plate 411 has on its inner surface a conductive film 412 connected to cathode 413 in order to prevent stability in light emission caused by electrostatic effects. Electrodes 414, 415 and 416 form the three sets of grid electrodes.
  • the edge portion 503 of the face plate is curved so that to an observer 510, light originating from portion 504 of the phosphor material would appear to originate from the virtual image 505.
  • the top surface 512 of the face plate were at right angles to the external surface of side plate 514, an observer at 510 would see a dark line whose width is equal to the widths of side plates 514 together with the spacing between the side plates.
  • the virtual image 505 it is preferable for the virtual image 505 to remain stationary in position even though the observer at position 510 may move in a direction parallel to surface 512 of the face plate. For this reason it is desirable to design the curvature of portion 503 to accomplish such purpose. This feature is illustrated in Fig. 5b.
  • the phosphor dot density can be further increased to over 60,000 dots/m2.
  • the spacing between the scanning electrodes in areas overlapping the filament such as areas 506 in Fig. 5a, may be made smaller than the spacing in areas where the scanning electrodes do not overlap any springs.
  • the denser spacing of the scanning electrodes will cause more electrons to be attracted to the area of the phosphor elements overlapping the springs; this will further increase the brightness of the display areas corresponding to the springs to achieve a more uniform brightness of the display.
  • the scanning voltages applied to the scanning electrodes overlapping the spring may be made higher than the voltages applied to scanning electrodes not overlapping the spring, again resulting in the pulling of electrons to the phosphor elements overlapping the spring to achieve uniform brightness.
  • Figs. 6a and 7 illustrate the control circuit for controlling the display of information of a mosaic device constructed using panels of the type such as device 101 shown in Fig. 1a.
  • the mosaic display includes N rows and M columns of panels 601.
  • the mosaic display may include only two rows and three columns of panels as shown in Fig. 7.
  • panel 601 includes anode 602, scanning electrodes G1, G3 (604) and data or brightness electrodes G2.
  • G1, G3 604
  • a cathode filament 607 is heated by means of the secondary coil of a DC/AC converter 609.
  • the primary coil is not shown in Fig. 6a but is located in block 118 of Fig. 1.
  • the secondary coil 609 supplies an AC voltage to filament 607, heating up the element as long as the mosaic display is on.
  • All the anodes 602 of the panels in Fig. 6a are connected to node 603 and a constant voltage is applied to the node.
  • the display functions of the mosaic display is achieved by applying different voltages to the filaments and the grid electrodes.
  • the DC voltage of all the elements in the first N rows of panels are all connected to a common node "1" in the connector 610.
  • This connection is made between node "1" through a variable resistor 611 to the center point of secondary coil 609 so that the DC level applied through the node is not affected by the AC voltage in coil 609.
  • the function of resistor 611 is to permit the user to adjust the DC voltage of the particular cathode in a panel so as to achieve uniformity in brightness as between panels.
  • each panel 601 in the N x M array in Fig. 6a has n rows and m columns of pixel dots as shown in Fig. 7. In the particular case in Fig. 7, each panel has twenty-four rows and thirty-six columns of pixel dots. As again shown in Fig.
  • This pattern again repeats for all the n pairs of scanning electrodes in the panel, thereby connecting the pairs to the corresponding n nodes in connector 606.
  • the voltage at node 1 in connector 610 remains low but the voltage applied to node 1 at connector 606 falls low; when this happens, there is either no potential difference or insufficient potential difference between the cathodes and the scanning electrodes for the first line of pixel dots so that the phosphor elements in such line no longer emits light.
  • one pixel dot line is scanned and emits light at the same time. This is different from conventional devices where it is necessary to scan more than one line at a time. The difference is due to the fact that the luminscence of the panels is greater than conventional devices so that full screen scanning is possible and it is unnecessary to scan more than one line at the same time. This greatly reduces the complexity of the circuitry and therefore the thickness of the display device.
  • Circuit 800 includes the video line 802 which supplies video data to be sampled and displayed. Such data is sampled by a shift register 804 driven by a clock line 806 and a line pulse D 808.
  • the shift register 804 closes switches 812 sequentially, causing the sampled video signal to be stored in capacitors 814.
  • the capacitors 814 would store a large number of samples of the video signal as sampled in a time sequence.
  • the sampled values are each applied to the input of a corresponding comparator 816 through a switch 818 where the comparator compares the stored samples to a saw tooth signal to line 820.
  • the amplitude of the samples stored in capacitors 814 are converted by the comparators into square pulses whose widths are proportional to the amplitude of the stored samples.
  • the outputs of the comparators 816 are then applied directly to the data electrodes in set G2 of the different panels in Fig. 6a in a manner described below.
  • the entire pixel dot line of all the panels in a particular row of panels is scanned or addressed at the same time.
  • all of the outputs of comparators 816 present on the grid lines in sets G2 will affect the brightness of such lines scanned.
  • switch 818 would permit the stored samples from capacitors 814 to be supplied to comparators 816 so that the corresponding pulse width modulated square pulses will be applied to the electrodes in sets G2.
  • the number of comparators 816 should equal at least the number of grid electrodes in the sets G2 in one row of panels.
  • Two circuits 800 are employed so that when one is supplying data, the other is sampling the video data to prepare for the next line scan.
  • the spacers used extend all the way between the face plate and the back plate of the panel. This is undesirable since it creates a bigger obstacle to electrons reaching the phosphor material on the anode.
  • three levels of spacers are used between the face plate 901 and back plate 902.
  • Planes 903, 904 and 905 are where the three sets of grid electrodes G1, G2, and G3 are located. Only one cathode 906 filament is shown as substantially parallel to the grid electrodes G2 in plane 904.
  • Spacers 907, 908, 909 and 910 are each in the form of elongated strips where the lengths of spacers 907 and 909 are substantially perpendicular to the plane of Fig.
  • spacers 908 and 910 are substantially parallel to the plane of Fig. 9.
  • alternate layers of spacers formed a staggered criss-crossing structure. This substantially reduces the obstruction posed by the spacers to the paths of the electrons between the cathode and the anode and therefore reduces the dark areas of the display compared to conventional designs.
  • these spacers serve to support and fix spatially the positions of the grid electrodes and reduces sagging or vibrations of the grid electrodes.
  • spacers As more elongated strip type spacers are used, it will be evident that other geometrical shapes of spacers may also be used such as circular or curved as long as they are again separated into sections, each section fitting between the planes of electrodes will perform a similar function and are within the scope of the invention.

Landscapes

  • Cathode-Ray Tubes And Fluorescent Screens For Display (AREA)
EP19910301882 1990-03-06 1991-03-06 Electronic fluorescent display system Withdrawn EP0446041A3 (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
CN90101232 1990-03-06
CN90101232.7A CN1026943C (zh) 1990-03-06 1990-03-06 平板彩色显示器
US07/657,867 US5170100A (en) 1990-03-06 1991-02-25 Electronic fluorescent display system
US657867 1991-02-25

Publications (2)

Publication Number Publication Date
EP0446041A2 true EP0446041A2 (de) 1991-09-11
EP0446041A3 EP0446041A3 (en) 1992-01-15

Family

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Application Number Title Priority Date Filing Date
EP19910301882 Withdrawn EP0446041A3 (en) 1990-03-06 1991-03-06 Electronic fluorescent display system

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Country Link
EP (1) EP0446041A3 (de)

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS57174840A (en) * 1981-04-17 1982-10-27 Matsushita Electric Ind Co Ltd Picture image display device
US4368404A (en) * 1979-12-13 1983-01-11 Chowa Giken Kabushiki-Kaisha Matrix-type fluorescent display device
JPS5832340A (ja) * 1981-08-20 1983-02-25 Matsushita Electric Ind Co Ltd 陰極構体の製造方法
US4591757A (en) * 1983-06-12 1986-05-27 U.S. Philips Corporation Color display tube having screen with sharply curved surfaces
EP0196115A2 (de) * 1985-03-29 1986-10-01 Mitsubishi Denki Kabushiki Kaisha Anzeigeeinheit
WO1990000808A1 (en) * 1988-07-06 1990-01-25 Innovative Display Development Partners Field emission cathode based flat panel display having polyimide spacers

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4368404A (en) * 1979-12-13 1983-01-11 Chowa Giken Kabushiki-Kaisha Matrix-type fluorescent display device
JPS57174840A (en) * 1981-04-17 1982-10-27 Matsushita Electric Ind Co Ltd Picture image display device
JPS5832340A (ja) * 1981-08-20 1983-02-25 Matsushita Electric Ind Co Ltd 陰極構体の製造方法
US4591757A (en) * 1983-06-12 1986-05-27 U.S. Philips Corporation Color display tube having screen with sharply curved surfaces
EP0196115A2 (de) * 1985-03-29 1986-10-01 Mitsubishi Denki Kabushiki Kaisha Anzeigeeinheit
WO1990000808A1 (en) * 1988-07-06 1990-01-25 Innovative Display Development Partners Field emission cathode based flat panel display having polyimide spacers

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
* abstract * *
PATENT ABSTRACTS OF JAPAN vol. 7, no. 111 (E-175)(1256) 14 May 1983 & JP-A-58 032 340 ( MATSUSHITA DENKI SANGYO K.K. ) 25 February 1983 *
PATENT ABSTRACTS OF JAPAN vol. 7, no. 17 (E-154)(1162) 22 January 1983 & JP-A-57 174 840 ( MATSUSHITA DENKI SANGYO K.K. ) 27 October 1982 *

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