Electronic fluorescent display

• US 5,565,742 A
• Filed: 07/02/1993
• Issued: 10/15/1996
• Est. Priority Date: 02/25/1991
• Status: Expired due to Fees

• Current Assignee: PixTech, Inc.
• Original Assignee: Panocorp Display Systems
• Inventors: Shichao, Ge, Liang, Jemm Y., Lam, Victor
• Primary Examiner(s): Issing, Gregory C.
• Application Number:
  US08/070,343
• Time in Patent Office: 1,201 Days
• Field of Search: 313/257, 313/249, 313/250, 313/252, 313/265, 313/417, 313/422, 313/474, 315/366
• US Class Current: 315/366
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• CPC Class Codes: H01J 1/18 Supports; Vibration-damping arrangements
• CPC Class Codes: H01J 2329/30 Shape or geometrical arrangement of the luminescent material
• CPC Class Codes: H01J 2329/8625 Spacing members
• CPC Class Codes: H01J 29/02 Electrodes; Screens; Mounting, supporting, spacing or insulating thereof
• CPC Class Codes: H01J 29/028 Mounting or supporting arrangements for flat panel cathode ray tubes, e.g. spacers particularly relating to electrodes
• CPC Class Codes: H01J 29/04 Cathodes
• CPC Class Codes: H01J 31/126 using line sources
• CPC Class Codes: H01J 31/15 with ray or beam selectively directed to luminescent anode segments printing by application of radiation B41J2/447

Abstract

In a cathodoluminescent display device, spacer elements are used to provide rigid mechanical support between the face and back plates when the chamber of the device is evacuated so that thin face and back plates may be used even for large-screen displays. The spacer support includes a spacer plate having holes therein for passage of electrons between the anode and cathode where a predetermined small number of one or more pixel dots corresponds to and spatially overlaps one hole, thereby reducing crosstalk. Shadow-reducing electrodes are employed on the back plate and spacer members alongside the cathode to cause the path of electrons from the cathode to the anode to spread out in order to reduce shadows caused by the presence of the spacer members. Various configurations of the two or three sets of grid electrodes may be employed to improve resolution and focusing. A linear array of cathode filament segments is used instead of one long integral cathode wire where the ends of the segments overlap to eliminate any visible gaps caused by the end portions of the segments being at lower temperatures than intermediate portions.

Claims

1. A cathodoluminescent visual display device having a plurality of pixel dots for displaying images when said device is viewed in a viewing direction, comprising:

a housing defining a chamber therein, said housing having a face plate, a back plate, and a side wall between the face and back plates surrounding and enclosing said chamber;

an anode on or near said face plate;

luminescent means that emits light in response to electrons, and that is on or adjacent to the anode;

at least one cathode in the chamber between the face and back plates;

at least a first and a second set of elongated grid electrodes between the anode and cathode, the electrodes in each set overlapping the luminescent means and grid electrodes in at least one other set at points when viewed in the viewing direction, wherein the overlapping points define pixel dots;

means for causing the cathode to emit electrons;

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 luminescent means at the pixel dots on or adjacent to the anode for displaying images; and

spacer means connecting the face and back plates to provide mechanical support for the plates so that the housing will not collapse when the chamber is evacuated, said spacer means including at least one spacer plate defining holes therein for passage of electrons between the anode and cathode, wherein a predetermined number of one or more pixel dots correspond to and spatially overlap one hole, thereby reducing crosstalk, said spacer plate attached to the side wall at locations surrounding the chamber to strengthen the housing against lateral forces.

2. The device of claim 1, wherein said anode and cathode are in two planes that are spaced apart, wherein the first and second sets of grid electrodes are in a first and a second plane respectively, said spacer means further comprising at least one net-shaped structure defining meshes that each permits electron passage to the luminescent means to address a plurality of pixel dots, said structure and said spacer plate rigidly connecting the face and back plates and the side wall.

3. The device of claim 1, wherein said face and back plates and the spacer plate have substantially the same planar dimensions, and wherein the three plates are attached directly or indirectly to the side wall at their edges to form a rigid structure.

4. The device of claim 2, said face and back plates being substantially parallel to each other, said spacer means further including elongated spacer members between the second plane and the back plate, said members connecting the structure to the back plate, wherein said structure, said spacer plate and spacer members include portions abutting each other and the face and back plates, said portions arranged along a line normal to the face and back plates forming a support for the face and back plates along said line, said device further comprising means for attaching said spacer plate, said spacer members to the face, back and side walls to form one rigid structure, wherein said structure comprises bars between meshes, said members being arranged so that they and some of the bars match and abut one another and lie along lines normal to the face and back plates.

5. The device of claim 2, wherein said structure comprises bars between meshes, and wherein each bar matches a space between two adjacent pixel dots.

6. The device of claim 2, wherein said structure comprises bars between meshes and adjacent to portions of the grid electrodes, wherein portions of at least some of the grid electrodes adjacent to the bars are spaced apart at closer spacings than those further away from the bars to reduce any dark shadows caused by the structure.

7. The device of claim 2, wherein said structure comprises bars between meshes and adjacent to portions of the grid electrodes, and wherein the potentials applying means applies potentials to at least some of the grid electrodes adjacent to the bars that are higher than those further away from the bars to reduce any dark shadows caused by the structure.

8. The device of claim 2, wherein said spacer means includes a plurality of said net-shaped structures, said structures being in the shape of plates placed substantially in a plane adjacent to one another to form a larger plate structure.

9. The device of claim 1, wherein said anode and cathode are in two planes that are spaced apart, wherein the first and second sets of grid electrodes are in a first and second plane respectively, said spacer plate being located between the anode and the closest of the first or second plane to the anode, said spacer plate defining holes therein having tapered surfaces, said spacer means further comprising at least one net-shaped structure, said structure including bars attached to one another to form the structure, said bars being tapered at substantially the same angle as the surfaces of the holes to form substantially smooth tapering surfaces.

10. The device of claim 1, wherein said anode and cathode are in two planes that are spaced apart, wherein the first and second sets of grid electrodes are in a first and second plane respectively, said spacer plate being located between the first and second planes, said spacer plate defining holes therein having tapered surfaces, said spacer means further comprising at least one net-shaped structure, said structure including bars attached to one another to form the structure, said bars being tapered at substantially the same angle as the surfaces of the holes to form substantially smooth tapering surfaces.

11. The device of claim 1, wherein the pixel dots are arranged in groups of adjacent dots displaying one or more colors, wherein each group of adjacent pixel dots for displaying the color or colors corresponds to and overlaps one hole in the viewing direction, said spacer plate further comprising means in said one hole for separating electrons addressing one of the group of pixel dots from electrons addressing a different one of the group of pixel dots to further reduce crosstalk.

12. The device of claim 11, wherein the pixel dots are arranged in groups of three or more adjacent dots displaying the colors red, green and blue, wherein each group of three or more adjacent pixel dots for displaying the colors red, green and blue correspond to and overlap one hole, said separating means comprising two or more separating walls separating the hole into three or more smaller holes, each corresponding to and overlapping each of the three or more red, green and blue pixel dots.

13. The device of claim 11, further comprising a conductive layer on said spacer plate or blocks to reduce the buildup of electrostatic charges.

14. The device of claim 1, further comprising adhesive means attaching said grid electrodes to said spacer means to reduce vibrations.

15. The device of claim 1, wherein said spacer plate is made of a photosensitive glass-ceramic material.

16. The device of claim 1, wherein dimensions of the holes at one side of the spacer plate are larger than those at the other side.

17. The device of claim 16, wherein the pixel dots are arranged in groups of adjacent dots, wherein each group corresponds to and overlaps one hole in the viewing direction, said spacer plate further comprising two or more separating walls separating at least one hole into smaller holes, each corresponding to and overlapping each of the pixel dots in a group of pixel dots corresponding to and overlapping said at least one hole, wherein each smaller hole tapers from one side of the spacer plate to the other, and wherein each smaller hole matches a pixel dot at the larger end of the hole.

18. The device of claim 16, wherein the holes at their larger dimensions match the pixel dots.

19. The device of claim 1, wherein said grid electrodes comprise wires, and wherein each hole is located so that it overlaps one wire, or two or more wires electrically connected, to form one or more electrodes for scanning the one or more pixel dots corresponding to the hole or controlling the brightness of such dots.

20. The device of claim 1, said spacer means further comprising adhesive means attaching the face, side wall and spacer plate or blocks to form a single rigid housing structure.

21. The device of claim 1, said spacer means including two or more spacer plates arranged in an array between the face and back plates, said spacer plates being net-shaped structures, wherein each of all of said spacer plates in the array, except for one or more of the spacer plates closest to the face plate, includes a side bar on one side of the net-shaped structure, said side bar attached to the side wall.

22. The device of claim 1, wherein said side wall is of such size that it extends from the face plate to the back plate or extends beyond the back plate.

23. The device of claim 22, further comprising wiring traces or other electrodes on inside surfaces of said side walls.

24. The device of claim 23, further comprising:

a printed circuit board attached to said back plate, said board having circuits thereon; and

electrical connection means connecting said grid electrodes to circuits on the board outside the housing through the wiring traces or other electrodes on the side wall surfaces.

25. The device of claim 1, wherein said grid electrodes comprises perforated or etched foil and elongated finger connectors.

26. The device of claim 25, wherein said side wall is of such size that it extends from the face plate to the back plate or extends beyond the back plate, and wherein said elongated finger connectors also extend beyond the back plate for connection to circuits outside the chamber.

27. The device of claim 1, wherein said grid electrodes are made of metal wire cloth meshes, wherein the orientation of the meshes is at an angle other than 0 or 90 degrees to the side walls, to minimize effect of thermal expansion differences.

28. The device of claim 1, said housing comprising both a side plate and a side wall, said side plate being a reinforcement bar in the chamber and attached to a surface of said side wall, wherein the reinforcement bar abuts and is attached to the back plate and the spacer plate.

29. The device of claim 1, wherein said side wall is at an acute angle to a plane normal to the face plate to reduce inter tile gap of front face plate and to minimize impact of dust or other foreign particles when the device is adjacent to other similar devices in a mosaic display.

30. The device of claim 1, further comprising a protective or buffering material wrapping, coating attached to the side wall at surfaces outside the chamber.

31. The device of claim 1, said device further comprising a metal core glass tube electrically connecting said anode to circuits outside the housing.

32. The device of claim 1, said device having an outgassing hole, said device further comprising a metal core glass tube through an isolation bench on top of, overlapping, but not covering up, the outgassing hole.

33. The apparatus of claim 1, wherein said side wall includes a unitary plate between and abutting the face and back plates.

34. The apparatus of claim 33, wherein the thickness of the side wall is in a range of about 0.2 mm to 2 mm.

35. The apparatus of claim 29, wherein said acute angle is less than about 10 degrees.

36. A cathodoluminescent visual display apparatus comprising a mosaic of devices arranged side by side to form a larger display, each device having a plurality of pixel dots for displaying images when viewed in a viewing direction and comprising:

a housing defining a chamber therein, said housing having a face plate, and a back plate;

an anode on or near said face plate;

luminescent means that emits light in response to electrons, and that is on or adjacent to the anode;

at least one cathode in the chamber between the face and back plates;

at least a first and a second set of elongated grid electrodes between the anode and cathode, the electrodes in each set overlapping the luminescent means and electrodes in at least one other set at points when viewed in the viewing direction, wherein the overlapping points define pixel dots;

means for causing the cathode to emit electrons;

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 luminescent means at the pixel dots on or adjacent to the anode for displaying images; and

spacer means connecting the face and back plates to provide mechanical support for the plates so that the housing will not collapse when the chamber is evacuated, said spacer means including a spacer plate defining holes therein for passage of electrons between the anode and cathode, wherein a predetermined number of one or more pixel dots correspond to and spatially overlap one hole, thereby reducing crosstalk.

37. The apparatus of claim 36, said housing further comprising a side wall between the face and back plates surrounding and enclosing said chamber, said spacer plate attached to the side wall at locations surrounding the chamber to strengthen the housing against lateral forces.

38. A cathodoluminescent visual display device which comprises:

a housing defining a chamber therein, said housing having a front face plate, a back face plate, and a side wall between the front and back plates surrounding and enclosing said chamber, said face plates and said side wall having inside surfaces facing the chamber;

at least one cathode;

an anode on or adjacent to the inside surface of the front face plate;

one or more layers of spacer plates or spacer bar arrays or layers of both placed between the front face and back face plates, said spacer plates and/or spacer bar arrays abutting one another and the front and back face plates to form a support for the front and back face plates when the chamber is evacuated, wherein said spacer plate layers, or spacer bar arrays, the front face plate and the back face plate define alignment holes therein;

alignment pins placed in said holes to fix the relative positions between said plates and/or arrays;

a multitude of cathodoluminescent phosphor dots on top of the anode;

at least a first and a second set of grid electrodes between the anode and cathodes and separated from the anode, cathode and each other by said layers of spacer plates or spacer bar arrays;

means for causing the cathode to generate an electron cloud; and

means for applying electrical potentials to the sets of grid electrodes, the anode and cathode, to cause the electrons in the cloud to travel from the cathode to the phosphor dots for displaying images.

39. The device of claim 38, said housing including a side wall, said device further comprising reinforcement bars attached to the inside surface of the side wall, said reinforcement bars abutting the back face plate and spacer plate or spacer bar array layers, wherein said side wall reinforcement bars have multiple alignment slots on one side, and wherein said spacer bar array layers have edges that fit into said slots, for aligning said layers relative to the side wall.

40. The device of claim 38, said housing including a side plate, said side plate abutting the back face plate and spacer plate or spacer bar array layers, wherein said side plate has multiple alignment slots on one side, and wherein said spacer bar array layers have edges that fit into said slots, for aligning said layers relative to the side plate.

41. The device of claim 38, wherein said spacer plate layers each comprises a plurality of spacer plates arranged adjacent to one another in substantially the same plane, each of such spacer plates having alignment through holes, protrusions and grooves that fit matching grooves and protrusions of adjacent spacer plates to enable high precision alignment of such spacer plates to form one of said spacer plate layers, and to enable such layers to withstand lateral forces on the device.

42. The device of claim 38, wherein the spacer bars have surfaces and are each made of a unitary piece of glass for increased mechanical strength, said spacer bars have through holes therein for alignment, and alignment slots to align the position of spacer bars with the side walls.

43. The device of claim 38, said device having layers of both spacer plates and spacer bar arrays, wherein said spacer bar array and the spacer plate layers all have tapered wall surfaces which, when stacked together and aligned using said alignment pins, will form a forest of wedge shaped walls between front face plate and back face plate, said wedge shaped walls being thicker at locations adjacent the back face plate than at locations adjacent the front face plate, and said forest of wedge shaped walls become being of a higher density at locations adjacent the front face plate than at locations adjacent the back face plate.

44. The device of claim 38, wherein said spacer plates have edges and define alignment notches along their edges for holding and aligning the grid electrodes.

45. The device of claim 38, wherein said alignment pins comprise glass tubes with electrically conductive cores, said cores connected to the anode to provide electrical connections to the anode.

46. The device of claim 38, further comprising adhesive means for attaching the front face plate, spacer plates, spacer bars and back face plate together along contacting surfaces to form one compound solid structure to provide high mechanical strength for large size display screens.

47. A cathodoluminescent visual display device which comprises:

a housing defining a chamber therein, said housing having a front face plate, a back face plate, and a side wall between the face and back plates surrounding and enclosing said chamber;

at least one cathode;

an anode on or adjacent to the inside surface of front face plate;

one or more layers of spacer plates or spacer bar arrays placed between the front face and back face plates, said spacer plates and/or spacer bar arrays abutting one another and the front and back face plates to form a support for the front and back face plates when the chamber is evacuated, said spacer plate defining holes therein for passage of electrons between the anode and cathode, wherein a predetermined number of pixel dots correspond to and spatially overlap one hole when the device is viewed in a viewing direction, thereby reducing crosstalk;

a multitude of cathodoluminescent phosphor dots on top of the anode;

at least a first and a second set of grid electrodes between the anode and cathodes and separated from the anode, cathode and each other by said layers of spacer plates or spacer bar arrays, wherein said grid electrodes comprise groups of parallel fine metal wires, metal wire cloth meshes, perforated or etched metal foils, or plated electrodes on the surfaces of the spacer plates or spacer bar arrays;

means for causing the cathode to generate an electron cloud; and

means for applying electrical potentials to the sets of grid electrodes, the anode and cathode, to cause the electrons in the cloud to travel from the cathode to the phosphor dots for displaying images.

48. The device of claim 47, wherein a first set of grid electrodes is for controlling the brightness of the display defining the data electrodes and a second set, defining the scanning electrodes that are transverse to the data electrodes, is for scanning lines of pixel dots across the anode and wherein the data electrodes comprise two arrays arranged with the data electrodes aligned substantially along a direction, so that each line of pixel dots along the direction of the data electrodes overlap two independently addressable data electrodes, so that two lines of pixel dots in two different areas of the image can be scanned simultaneously.

49. A cathodoluminescent visual display device which comprises:

a housing defining a chamber therein, said housing having a face plate, a back plate, and a side wall between the face and back plates surrounding and enclosing said chamber;

at least one cathode;

an anode on or adjacent to the inside surface of front face plate;

one or more layers of spacer plates or spacer bar arrays placed between the front face and back face plates;

a multitude of cathodoluminescent phosphor dots on top of the anode;

at least a first and a second set of grid electrodes between the anode and cathodes and separated from the anode, cathode and each other by said layers of spacer plates or spacer bar arrays;

means for causing the cathode to generate an electron cloud; and

means for applying electrical potentials to the sets of grid electrodes, the anode and cathode, to cause the electrons in the cloud to travel from the cathode to the phosphor dots for displaying images;

wherein one or more of the said side walls, the spacer bars, spacer plates and the back face plate have electrodes printed on their surfaces in or facing the chamber, said electrodes containing material that emits secondary electrons upon being impinged by electrons, thereby spreading out the electrons generated by the cathode to improve the uniformity of the device and countering the electric field caused by static charge build up.

50. A cathodoluminescent visual display device which comprises:

a housing defining a chamber therein, said housing having a face plate, a back plate, and a side wall between the face and back plates surrounding and enclosing said chamber;

at least one cathode;

an anode on or adjacent to the inside surface of front face plate;

one or more layers of spacer plates or spacer bar arrays placed between the front face and back face plates, said spacer plates and/or spacer bar arrays abutting one another and the front and back face plates to form a support for the front and back face plates when the chamber is evacuated;

a multitude of cathodoluminescent phosphor dots on top of the anode, areas of the dots that emit light upon impingement of electrons defining the active areas of the dots, wherein the active areas of at least some dots are different from those of other dots;

at least a first and a second set of grid electrodes between the anode and cathodes and separated from the anode, cathode and each other by said layers of spacer plates or spacer bar arrays;

means for causing the cathode to generate an electron cloud; and

means for applying electrical potentials to the sets of grid electrodes, the anode and cathode, to cause the electrons in the cloud to travel from the cathode to the phosphor dots for displaying images.

51. The device of claim 50, wherein at least some phosphor dots are larger and contain larger active areas than other phosphor dots.

52. The device of claim 50, wherein, for a group of phosphor dots, the dots are of the same size but some dots contain smaller areas that do not emit light upon impingement of electrons than others in the group.

53. A cathodoluminescent visual display device which comprises:

a housing defining a chamber therein, said housing having a face plate, a back plate, and a side wall between the face and back plates surrounding and enclosing said chamber;

at least one cathode;

an anode on or adjacent to the inside surface of front face plate;

one or more layers of spacer plates or spacer bar arrays placed between the front face and back face plates, said spacer plates and/or spacer bar arrays abutting one another and the front and back face plates to form a support for the front and back face plates when the chamber is evacuated, said spacer plate defining holes therein for passage of electrons between the anode and cathode, wherein a predetermined number of one or more pixel dots correspond to and spatially overlap one hole, thereby reducing crosstalk,

a multitude of cathodoluminescent phosphor dots on top of the anode;

at least a first and a second set of grid electrodes between the anode and cathodes and separated from the anode, cathode and each other by said layers of spacer plates or spacer bar arrays;

means for causing the cathode to generate an electron cloud; and

means for applying electrical potentials to the sets of grid electrodes, the anode and cathode, to cause the electrons in the cloud to travel from the cathode to the phosphor dots for displaying images;

wherein said phosphor dots are arranged in linear arrays of the same color selected from the group;

red, green and blue.

54. The device of claim 53, wherein said arrays are vertical columns, said columns forming an alternating pattern of the following sequence:

a red column, a green column and a blue column.

55. The device of claim 53, wherein said arrays are vertical columns, said columns forming an alternating pattern of the following sequence:

a red column, a green column, a blue column and another green column.

56. The device of claim 53, wherein said arrays are diagonally oriented when viewed in the viewing direction, said arrays forming an alternating pattern of the following sequence:

a red array, a green array, a blue array and another green array.

57. A cathodoluminescent visual display device which comprises:

a housing defining a chamber therein, said housing having a face plate, a back plate, and a side wall between the face and back plates surrounding and enclosing said chamber;

at least one cathode;

an anode on or adjacent to the inside surface of front face plate;

one or more layers of spacer plates or spacer bar arrays placed between the front face and back face plates;

a multitude of cathodoluminescent phosphor dots on top of the anode;

wherein said front face plate is made of, or includes a layer of, spectrum selective glass with transmittance peaks that match the emission peaks of the said cathodoluminescent phosphor dots;

at least a first and a second set of grid electrodes between the anode and cathodes and separated from the anode, cathode and each other by said layers of spacer plates or spacer bar arrays;

means for causing the cathode to generate an electron cloud; and

means for applying electrical potentials to the sets of grid electrodes, the anode and cathode, to cause the electrons in the cloud to travel from the cathode to the phosphor dots for displaying images.

58. The device of claim 57, said phosphors including three types of phosphor dots that emit red, green and blue light, wherein said front face plate is made of spectrum selective glass with three transmittance peaks that match the emission peaks of the said red, green and blue cathodoluminescent phosphors.

59. The device of claim 57, wherein said phosphor dots include different types that emit light of different colors, wherein said front face plate comprises a transparent plate and, on the transparent plate, a filter coating in the shape of a two dimensional array of different types of filter dots, the different types of dots for filtering light of different colors, each type of filter dots being located on the transparent plate so that they overlap the corresponding phosphor dot of the same color when viewed in a viewing direction of the device, wherein, each filter dot'"'"'s transmittance peak matches the emission peaks of the corresponding phosphor dot.

60. The device of claim 59, said front face plate having an outside surface not in the chamber, wherein said filter dot array is coated on the outside surface of the front face plate, said array being located so that there are gaps G between the filter dots of different color.

61. A cathodoluminescent visual display device which comprises:

a housing defining a chamber therein, said housing having a face plate, a back plate, and a side wall between the face and back plates surrounding and enclosing said chamber;

wherein said front face plate comprises a Fresnel optical lens;

at least one cathode;

an anode on or adjacent to the inside surface of front face plate;

one or more layers of spacer plates or spacer bar arrays placed between the front face and back face plates;

a multitude of cathodoluminescent phosphor dots on top of the anode;

at least a first and a second set of grid electrodes between the anode and cathodes and separated from the anode, cathode and each other by said layers of spacer plates or spacer bar arrays;

means for causing the cathode to generate an electron cloud; and

means for applying electrical potentials to the sets of grid electrodes, the anode and cathode, to cause the electrons in the cloud to travel from the cathode to the phosphor dots for displaying images.