JP3813967B2 - Fluorescent display device - Google Patents

Description

  The present invention relates to a fluorescent display device using a phosphor that emits and emits light by collision of electrons.

  A fluorescent display device is an electron tube that uses light emitted by causing electrons emitted from an electron emitting portion to collide with a fluorescent substance in a vacuum container at least one of which is transparent. As this fluorescent display device, a triode structure having a grid for controlling the function of electrons is most often used. One type of such a fluorescent display device is an image tube that constitutes a pixel of a large screen display device.

  As shown in FIG. 14, the conventional picture tube includes a vacuum vessel (envelope) in which a face glass 302 having translucency is bonded and fixed to a cylindrical glass bulb 301 with a low melting point frit glass 303. A fluorescent screen 304, an anode electrode assembly 305, and a cathode assembly 306 constituting an electron emission portion are disposed therein. The face glass 302 has a convex lens-shaped spherical surface portion 302a formed on the front side, and a flange-shaped stepped portion 302b formed on the peripheral edge portion. A fluorescent screen 304 is formed on the main surface of the inner surface 302 c, and an Al metal back film 307 is formed on the surface of the fluorescent screen 304.

  One end side of a contact piece 307a having an elastic force formed by processing, for example, a stainless steel thin plate by a press molding method is inserted in a peripheral portion of the inner surface 302c of the face glass 302. The contact piece 307a is bonded and fixed to a predetermined portion of the inner surface 302c of the face glass 302 by contacting the Al metal back film 307 with a conductive adhesive made of, for example, a mixture of carbon or silver and frit glass. The other end side of the contact piece 307 a extends toward the inner wall surface of the glass bulb 301.

  Further, lead pins 309a to 309e are inserted into the stem glass 308 constituting the bottom of the glass bulb 301, and in addition, an exhaust pipe 308a is integrally formed. An anode lead 310 is fixed to the tip of the lead pin 309a on the stem glass 308 by welding, and a cylindrical anode electrode assembly 305 is fixed to the tip of the anode lead 310 by welding. The anode electrode assembly 305 includes, for example, a ring-shaped anode 305a formed by rolling a metal wire made of stainless steel into a ring shape, and a portion in which a rectangular stainless steel thin plate is wound around the outer peripheral surface of the ring-shaped anode 305a and overlapped. And a cylindrical anode 305b formed in a cylindrical shape by welding at two points.

This anode electrode assembly 305 is welded to the tip of the anode lead 310 at a predetermined location with the ring-shaped anode 305a, and further welded at the contact portion with the inside of the cylindrical anode 305b at the most distal end portion of the anode lead 310. ing. Further, a Ba getter 305c is attached to a part of the ring-shaped anode 305a by welding.
Further, cathode leads 311b to 311e are attached to the tip portions of the lead pins 309b to 309e by welding, and a cathode structure 306 is fixedly disposed to the tip portions of the cathode leads 311b to 311e by welding.

  The cathode structure 306 is configured as follows. First, a back electrode 306b is disposed at the center on the ceramic substrate 306a, and a filament cathode 306c, which is an electron emission portion, is disposed above the back electrode 306b with a predetermined interval. Further, a grid housing 306d having an elliptical opening 306f is mounted on the ceramic substrate 306a so as to cover them. Further, a mesh-like grid 306e is welded to the fluorescent screen 304 side of the grid housing 306d so as to cover the opening 306f.

  The image tube configured as described above applies a predetermined voltage to the filament cathode 306c via the cathode leads 311c and 311d by first supplying a voltage (heating power) to the lead pins 309c and 309d from an external circuit. Thus, thermal electrons are emitted. Further, by supplying a voltage from the external circuit to the lead pin 309b, a negative potential is applied to the back electrode 306b via the cathode lead 311b with respect to the filament cathode 306c. In addition, by supplying a voltage to the lead pin 309e from an external circuit, a positive potential is applied to the grid housing 306d with respect to the filament cathode 306c via the cathode lead 311e, so that the mesh grid 306e of the grid housing 306d An electron beam is emitted.

  Then, a high voltage is supplied from the external circuit to the lead pin 309a, and the high voltage is applied to the Al metal back film 307 through the paths of the anode lead 310 → the anode electrode assembly 305 (cylindrical anode 305b) → the contact piece 307a. In this state, the emitted electrons are accelerated by the cylindrical anode 305b, penetrate the Al metal back film 307, and collide with the phosphor screen 304. As a result, the phosphor screen 304 is excited by electron impact, and emits light with a light emission color corresponding to the phosphor constituting the phosphor screen 304. This emitted light is transmitted through the face glass 302 and emitted from the spherical portion 302a on the front surface side, and is displayed.

Such an image tube has a problem in that the beam diameter increases until the electron beam exiting the mesh grid reaches the phosphor screen, so that the light emission area is widened and a clear display cannot be obtained. Further, the beam diameter is widened, which hinders the improvement of light emission luminance.
The present invention has been made to solve the above-described problems, and provides a fluorescent display device capable of converging an electron beam with a simple structure and providing a clear display and improved light emission luminance. With the goal.

  In order to solve the above-described problems, the fluorescent display device according to the present invention includes at least one electron emission portion, an anode, and a control electrode disposed at a predetermined distance between the electron emission portion and the anode. A built-in envelope including at least part of a light-transmitting display surface and the inside of which is evacuated, and an anode applied to the inner wall on the display surface side of the envelope and emitted from the electron emission portion A metal member having an opening through which the control electrode passes electrons emitted from the electron emission portion to the display surface side, and an opening portion. And a metal mesh member disposed between the metal member and the electron emission portion so as to cover the metal member and electrically connected to the metal member.

In this case, one configuration example of the metal mesh member is shaped into a shape in which the central portion protrudes from the opening of the metal member in the direction of the electron emission portion. Another configuration example of the metal mesh member includes a planar lattice member and a spacer member for separating the lattice member from the opening of the metal member in the direction of the electron emission portion.
In the configuration example of the metal member of the fluorescent display device described above, the opening is formed in a circular shape. In another configuration example of the metal member, the opening is formed in an oval shape.

In one configuration example of the metal member of the fluorescent display device in which the phosphor film has a rectangular shape, the opening is formed in a shape that is long in the longitudinal direction of the phosphor film.
One configuration example of the electron emission portion of the above-described fluorescent display device includes a filament cathode that emits thermoelectrons when energized and heated. Further, another configuration example of the electron emission portion is configured by carbon nanotubes. Still another configuration example of the electron emission portion includes a carbon nanotube having an open end.
In one configuration example of the display surface of the fluorescent display device described above, phosphor films having different emission colors are arranged adjacent to each other.

  As described above, the fluorescent display device of the present invention includes at least one electron emission portion, an anode, and at least one control electrode disposed at a predetermined distance between the electron emission portion and the anode, And at least a part of the envelope containing a light-transmitting display surface and the inside of which is evacuated, and applied to the inner wall of the envelope on the display surface side, emitted from the electron emission portion and accelerated by the anode. At least one phosphor film that emits and emits light by collision of electrons, and the control electrode covers the opening and a metal member having an opening through which electrons emitted from the electron emitting portion pass to the display surface side. Since the metal mesh member is disposed between the metal member and the electron emission portion and electrically connected to the metal member, the equipotential surface near the opening is formed on the metal mesh member side. Bend. As a result, electrons passing through the periphery of the opening are deflected toward the center of the opening, so that it is possible to obtain an effect of enabling light emission display with good convergence of the electron beam on the phosphor screen and improvement of light emission luminance.

Embodiments of the present invention will be described below with reference to the drawings.
First, a first reference example in the fluorescent display device of the present invention will be described.
FIG. 1 shows the configuration of an image tube which is a first reference example of the present invention. In FIG. 1, (a) shows the overall configuration, and (b) shows the top surface of a grid housing having a mesh-like grid. The image tube in this reference example has a vacuum vessel (envelope) in which a face glass 102 is bonded and fixed to a cylindrical glass bulb 101 with a low melting point frit glass 103, and a phosphor screen 104 and an anode are included therein. An electrode assembly 105 and a cathode assembly 106 constituting an electron emission portion are disposed.

  In this case, the face glass 102 has a convex lens-shaped spherical surface portion 102a formed on the front side and a flange-shaped stepped portion 102b formed on the peripheral edge portion. Although not shown in the figure, an inner surface 102c of the face glass 102 is formed with a concave recess in a part of its peripheral portion. A fluorescent screen 104 is formed on the main surface of the inner surface 102c, and an Al metal back film 107 is formed on the surface of the fluorescent screen 104. Note that the phosphor screen 104 is not formed in the above-described recess, and only the Al metal back film 107 is formed. In the recess, for example, one end side of a contact piece 107a having elastic force formed by processing a thin plate of stainless steel by a press molding method is inserted. The contact piece 107a is formed by bonding and fixing to a concave portion of a conductive adhesive made of a mixture of carbon or silver and frit glass, for example. The other end of the contact piece 107 a extends toward the inner wall surface of the glass bulb 101.

Here, the phosphor screen 104 is a white phosphor, for example, after a paste prepared by dissolving a Y ₂ O ₂ S: Tb + Y ₂ O ₃ : Eu mixed phosphor in a solvent is printed on the inner surface 102 c with a thickness of about 20 μm. Dry to form. Note that the phosphor screen 104 is not applied in the recesses (not shown). The Al metal back film 107 is formed by depositing an aluminum film with a thickness of about 150 nm on the surface of the phosphor screen 104 by vapor deposition. Here, since the fluorescent screen 104 is not applied inside the recess, only the Al metal back film 107 is formed. After forming the phosphor screen 104 and the Al metal back film 107, the face glass 102 is baked in the air at 560 ° C. for about 30 minutes, for example, by an electric furnace or the like to remove the solvents in the coating film. If the Al metal back film 107 is too thin, pinholes increase and reflection on the phosphor screen 104 decreases. On the other hand, if the thickness is too thick, the penetration of the electron beam into the phosphor screen 104 is hindered and the light emission becomes weak. Therefore, control of the thickness of the Al metal back film 107 is important. Therefore, as described above, the Al metal back film 107 should have a thickness of about 150 nm.

  The face glass 102 is, for example, fitted with a low melting point frit glass 103 with a flange-shaped stepped portion 102b fitted into one open end of a glass bulb 101 having a diameter of about 20 mm and a length of about 50 mm and cut at both ends. ing. This is formed by applying a low melting point frit glass paste to the bonding surface, bringing the stepped portion 102b of the face glass 102 and the opening end of the glass bulb 101 together through the low melting point frit glass paste, and heating and firing these. Is done. As a matter of course, the face glass 102 is bonded and fixed to the glass bulb 101 after the phosphor screen 104, the anode electrode structure 105, and the cathode structure 106 constituting the electron emission portion are arranged.

  Further, the bottom of the glass bulb 101 is constituted by a stem glass 108, through which lead pins 109a to 109e are inserted, and in addition, an exhaust pipe 108a is integrally formed. An anode lead 110 is fixed to the tip of the lead pin 109a on the stem glass 108 by welding, and a cylindrical anode electrode assembly (electron acceleration electrode) 105 is fixed to the tip of the anode lead 110 by welding. The anode electrode assembly 105 includes, for example, a ring-shaped anode 105a formed by rolling a stainless steel metal wire having a wire diameter of about 0.5 mm into a ring shape, and a rectangular shape having a plate thickness of 0.01 to 0.02 mm. A stainless steel plate is wound around the outer peripheral surface of the ring-shaped anode 105a, and the overlapping portion is welded at two points to form a cylindrical anode 105b formed in a cylindrical shape.

In this anode electrode assembly 105, a ring-shaped anode 105 a is welded to a tip portion of the anode lead 110 at a predetermined location, and an inner side of the cylindrical anode 105 b is welded to the most distal portion of the anode lead 110. A Ba getter 105c is attached to a part of the ring-shaped anode 105a by welding. In addition, cathode leads 111b to 111e are attached to the tip portions of the lead pins 109b to 109e by welding, and the cathode structure 106 is fixedly disposed to the tip portions of the cathode leads 111b to 111e by welding. In FIG. 1A, the anode electrode assembly 105, the anode lead 110, the cathode leads 111b to 111e, the lead pins 109a to 109e, and the exhaust pipe 108a are not shown in cross section.
The above is almost the same as that of the conventional picture tube.

  The cathode structure 106 includes a ceramic substrate 106a, a back electrode 106b disposed in the center of the ceramic substrate 106a, a filament cathode 106c disposed above the back electrode 106b at a predetermined interval, and a ceramic substrate so as to cover them. It is comprised from the grid housing 106d mounted on 106a. The back electrode 106b is a cap whose outer shape obtained by press-molding a stainless steel plate is a rectangular parallelepiped, and is connected to the cathode lead 111c through a mounting hole (not shown) provided in the ceramic substrate 106a. The filament cathode 106c, which is an electron emission portion, is supported by two filament supports 106j attached on the ceramic substrate 106a, and the two filament supports 106j are connected to the cathode leads 111b and 111d, respectively.

  The grid housing 106d is a cap having a rectangular parallelepiped shape, and an elliptical opening 106f having a major axis of 6 mm and a minor axis of 4 mm is provided in a portion facing the filament cathode 106c. A mesh-like grid 106e is arranged between the opening 106f and the filament cathode 106c, and the mesh-like grid 106e is arranged via a spacer 106i for maintaining a predetermined distance from the opening 106f. It is attached to the housing 106d. Here, the grid housing 106d, the spacer 106i, and the mesh grid 106e are all made of stainless steel, and are welded to each other so that the mesh grid 106e is electrically connected to the cathode lead 111e via the spacer 106i and the grid housing 106d. ing. The grid housing 106d is formed by press-molding a stainless steel plate having a plate thickness of about 200 μm.

  The image tube configured as described above applies a predetermined potential to the filament cathode 106c via the cathode leads 111b and 111d by first supplying a voltage (heating power supply) to the lead pins 109b and 109d from an external circuit. Thus, thermal electrons are emitted. Further, by supplying a voltage to the lead pin 109c from an external circuit, a negative potential is applied to the back electrode 106b via the cathode lead 111c with respect to the filament cathode 106c. In addition, by supplying a voltage to the lead pin 109e from an external circuit, a positive potential is applied to the grid housing 106d via the cathode lead 111e with respect to the filament cathode 106c, so that the mesh grid 106e of the grid housing 106d An electron beam is emitted.

  Further, a high voltage is supplied from an external circuit to the lead pin 109a, and the high voltage is applied to the Al metal back film 107 through the respective paths of the anode lead 110 → the anode electrode assembly 105 (cylindrical anode 105b) → the contact piece 107a. In this state, the emitted electrons are accelerated by the cylindrical anode 105b, penetrate the Al metal back film 107, and collide with the phosphor screen 104. As a result, the phosphor screen 104 is excited by electron impact, and emits light with a light emission color corresponding to the phosphor constituting the phosphor screen 104. The emitted light passes through the face glass 102 and is emitted from the spherical portion 102a on the front surface side to be displayed.

  In this reference example, as shown in FIG. 2, since a step is formed between the grid housing 106d and the mesh grid 106e, the equipotential surface 130 in the vicinity of the opening 106f is curved toward the mesh grid 106e. To do. As a result, electrons passing through the periphery of the opening 106f are deflected toward the center of the opening 106f, so that an electron beam is converged on the fluorescent screen 104 and can be used as a point light source to display light with good brightness. Become. In this case, the distance between the Al metal back film 107 and the opening 106f is 25 mm, the distance between the mesh grid 106e and the opening 106f is 0.7 to 1.5 mm, and the anode voltage applied to the Al metal back film 107 is The grid voltage applied to 10 KV and the mesh-like grid 106e was 300-500V. As a result, the light emitting portion of the phosphor screen 104 was narrowed down to an area of 5 mm with respect to the diameter of the face glass 102 of about 20 mm. According to this reference example, there is an advantage that the degree of convergence of the electron beam 131 can be easily adjusted by changing the thickness of the spacer 106i.

Next, a second reference example in the fluorescent display device of the present invention will be described.
FIGS. 3A and 3B show a configuration of an image tube according to a second reference example of the present invention, in which FIG. 3A shows the overall configuration and FIG. 3B shows an upper surface of a grid housing having a mesh grid. 1 denote the same parts. This image tube is different from that shown in FIG. 1 in that the mesh-like grid 106h is shaped concavely and directly attached to the grid housing 106d. In this case, the mesh grid 106h is shaped to be curved toward the filament cathode 106c with a predetermined curvature so that the electron beam converges on the phosphor screen 104.

  Also in this reference example, as shown in FIG. 4, the equipotential surface 130 in the vicinity of the opening 106f is curved toward the mesh grid 106h, and electrons passing through the opening 106f are deflected toward the center of the opening 106f. Therefore, the light emission display with good brightness and brightness that can be used as a point light source by allowing the electron beam 131 to converge on the phosphor screen 104 becomes possible. According to this reference example, since the curved mesh grid 106h only needs to be welded to the grid housing 106d, there is an advantage that the structure is simple and the assembly is easy.

Next, a third reference example in the fluorescent display device of the present invention will be described.
FIG. 5 shows the configuration of an image tube which is a third reference example of the present invention. In FIG. 5, (a) shows the overall configuration, (b) to (e) show details of the electron emission section, and (f) shows Figure 3 shows the top surface of a grid housing with a mesh grid. 1 denote the same parts. This image tube is different from that shown in FIG. 1 in that the opening 106f is circular and that a field emission electron emission source using carbon nanotubes as an electron source is used for the electron emission portion of the cathode structure 106. It is.

  In this reference example, the cathode structure 106 was configured as follows. A substrate electrode 126 having a rectangular parallelepiped shape is disposed at the center of the ceramic substrate 106a, and connection wiring is drawn from the substrate electrode 126 to the lower side of the ceramic substrate 106a through a through hole (not shown) provided in the ceramic substrate 106a. And connected to the cathode lead 111f. Further, as shown in an enlarged view in FIG. 5B, in the region of about 3 mmφ on the upper surface of the substrate electrode 126, a needle-like columnar graphite 121 made of an aggregate of carbon nanotubes and having a length of several millimeters is almost in the longitudinal direction. The conductive adhesive 122 is fixedly arranged in the direction of the fluorescent screen 104.

  The columnar graphite 121 is fixed by, for example, disposing the columnar graphite 121 on the substrate electrode 126 via the conductive adhesive 122 to volatilize the solvent of the conductive adhesive 122 and then 400 to 600 in the air. What is necessary is just to heat for about 15 to 60 minutes and to bake at about degreeC. In this way, by performing firing in an atmosphere in which oxygen is present, the carbon powder adhering to the columnar graphite 121 as a by-product during the manufacturing process can be burned off. If this carbon powder remains, it may be scattered by vibrations or the like, which may cause adverse effects. Note that this baking may be performed in an atmosphere evacuated to about 0.1 Pa, for example.

As shown in FIG. 5C, the columnar graphite 121 is a structure in which carbon nanotubes 121a are gathered in substantially the same direction. In addition, this FIG.5 (c) is a perspective view which sees the cross section which cut the columnar graphite 121 on the way.
For example, as shown in FIG. 5 (d), the carbon nanotube 121a is completely graphitized to form a cylindrical shape, and its diameter is about 4 to 50 nm, and its length is on the order of microns. And as shown in FIG.5 (e), the front-end | tip part is closed when a five-membered ring enters.

  This carbon nanotube is a deposit in which carbon on the anode side evaporates and aggregates at the tip of the carbon electrode on the cathode side by causing a direct current arc discharge in a state where the two carbon electrodes are separated by about 1 to 2 mm in helium gas. Can be formed inside. That is, a stable arc discharge is maintained in helium with the gap between the carbon electrodes kept at about 1 mm, and a cylindrical deposit having a diameter substantially the same as the diameter of the carbon electrode of the anode is formed at the cathode tip. . This cylindrical deposit is composed of two regions: an outer hard shell made of graphite polycrystal and a fragile and black core inside. The inner core extends in the length direction of the deposit column. Has a stretchy fibrous structure. This fibrous structure is the above-described columnar graphite, and columnar graphite can be obtained by cutting out a deposit column.

  In this columnar graphite, a plurality of carbon nanotubes are aggregated together with carbon polyhedral fine particles (nanopolyhedron). This carbon nanotube has a shape in which a single layer of graphite schematically shown in FIGS. 5 (d) and 5 (e) is closed in a cylindrical shape, and a plurality of graphite layers are stacked in a nested structure. There is a shape that has a coaxial multilayer structure closed in a cylindrical shape, either of which may be used.

  Further, since the central axis portion of these carbon nanotubes is hollow, it is possible to obtain carbon nanotubes having a tip portion that is bent and opened in the middle. In this case, since the tip becomes sharper and higher electric field concentration can be obtained and the amount of electron emission can be increased, a carbon nanotube having such a tip opened may be used. Such a carbon nanotube having an open end is obtained by cutting the columnar graphite in the middle or by breaking and breaking the columnar graphite. Therefore, the cut or broken surface of the columnar graphite processed in this way has a phosphor screen 104. What is necessary is just to fix and arrange with the conductive adhesive 122 so that it may face in the direction. In addition, carbon nanotubes in which carbon enters the cavity of the central axis portion may be obtained in the columnar graphite, but it goes without saying that even those carbon nanotubes can be used as an electron emission source. In this case, you may make it use as a carbon nanotube with which the front-end | tip opened above.

  As described above, in this reference example, the substrate electrode 126 and the columnar graphite 121 constitute an electron emission portion, and electrons are emitted from the tips of the carbon nanotubes 121 a included in the columnar graphite 121. A grid housing 106d is mounted on the ceramic substrate 106a so as to cover the electron emission portion. Since the grid housing 106d is the same as that shown in FIG. 1 except that the opening 106f is circular, the description thereof is omitted.

  The image tube configured as described above first applies an electric field between the substrate electrode 126 and the grid housing 106d via the cathode leads 111f and 111e by supplying a voltage to the lead pins 109f and 109e from an external circuit. As a result, a high electric field is concentrated on the tip of the carbon nanotube 121a of the columnar graphite 121 fixedly disposed on the substrate electrode 126, and electrons are drawn out and emitted from the mesh grid 106e.

  Further, a high voltage is supplied from the external circuit to the lead pin 109a, and the high voltage is applied to the Al metal back film 107 through the respective paths of the anode lead 110 → the anode electrode assembly 105 (cylindrical anode 105b) → the contact piece 107a. In this state, the emitted electrons are accelerated by the cylindrical anode 105b, penetrate the Al metal back film 107, and collide with the phosphor screen 104. As a result, the phosphor screen 104 is excited by electron impact, and emits light with a light emission color corresponding to the phosphor constituting the phosphor screen 104. The emitted light passes through the face glass 102 and is emitted from the spherical portion 102a on the front surface side to be displayed.

  According to this reference example, as shown in FIG. 6, since the equipotential surface 130 in the vicinity of the opening 106f is curved toward the mesh-like grid 106e, electrons passing through the vicinity of the opening 106f are directed toward the center of the opening 106f. The electron beam 131 is converged on the fluorescent screen 104 by being deflected. As a result, it is possible to perform light emitting display with good brightness and brightness that can be used as a point light source. In this case, there is an advantage that the degree of convergence of the electron beam 131 can be easily adjusted by changing the thickness of the spacer 106i.

  In this reference example, the opening 106f is circular, the interval between the Al metal back film 107 and the opening 106f is 25 mm, the interval between the mesh grid 106e and the opening 106f is 0.7 to 1.5 mm, and the mesh grid 106e. And the distance between the tip of the columnar graphite 121 was about 0.5 to 1 mm. The anode voltage applied to the Al metal back film 107 was 10 KV, the grid voltage applied to the mesh grid 106 e was 300 to 500 V, and the cathode voltage applied to the substrate electrode 126 was 0 V. As a result, the light emitting portion of the phosphor screen 104 was narrowed down to an area of 5 mm in diameter with respect to the diameter of the face glass 102 of about 20 mm. It should be noted that the distance between the mesh grid 106e and the tip of the columnar graphite 121 should be as close as possible within a range where no discharge occurs.

  In addition to the effects of the first reference example, the image tube according to this reference example uses a field emission type electron emission source using carbon nanotubes in the electron emission portion, and thus requires a weak cathode filament-like component. Therefore, it can be easily handled and can be easily manufactured. In addition, since a heating power source for the cathode filament is not required, the number of lead pins can be reduced and the manufacturing can be simplified.

  Next, a fourth reference example in the fluorescent display device of the present invention will be described. FIGS. 7A and 7B show the configuration of an image tube which is a fourth reference example of the present invention, in which FIG. 7A shows the overall configuration and FIG. 7B shows the top surface of a grid housing having a mesh grid. 1 to 5 indicate the same parts. This image tube is different from that shown in FIG. 5 in that the mesh-like grid 106h is formed into a concave shape and directly attached to the grid housing 106d. In this case, the mesh grid 106h is shaped to be curved toward the columnar graphite 121 side with a predetermined curvature so that the electron beam converges on the phosphor screen 104.

  Also in this reference example, as shown in FIG. 8, the equipotential surface 130 in the vicinity of the opening 106f is curved to the mesh-like grid 106h side, and electrons passing near the opening 106f are deflected toward the center of the opening 106f. Therefore, the light emission display with good brightness and brightness that can be used as a point light source by allowing the electron beam 131 to converge on the phosphor screen 104 becomes possible. According to this reference example, since the curved mesh grid 106h only needs to be welded to the grid housing 106d, there is an advantage that the structure is simple and the assembly is easy.

Next, a first embodiment of the fluorescent display device according to the present invention will be described.
FIGS. 9A and 9B show the configuration of the image tube according to the first embodiment of the present invention, in which FIG. 9A shows the overall configuration, and FIG. 9B shows the configuration of the mesh-like grid mounting portion of the grid housing. FIG. 10 shows a partial cross section of the image tube. In the image tube in this embodiment, a front panel 202 and a back panel 208 are arranged to face each other via a frame-shaped side plate 201, which are bonded and fixed by a low melting point frit glass 203, and the inside is hermetically sealed and vacuumed. A container (envelope) is formed, in which a phosphor screen 204, an anode electrode assembly 205, and a cathode assembly 206 constituting an electron emission unit are arranged. As a matter of course, after arranging the phosphor screen 204, the anode electrode assembly 205, and the cathode assembly 206 constituting the electron emission portion, the front panel 202, the back panel 208, and the frame-shaped side plate 201 are bonded and fixed. .

  On the inner surface of the front panel 202, a phosphor screen 204 is formed in which pixels composed of a red light-emitting phosphor layer 204R, a green light-emitting phosphor layer 204G, and a blue light-emitting phosphor layer 204B are arranged in a matrix of 4 rows and 4 columns. An anode wiring 214 is formed around each phosphor layer 204R, 204G, 204B to contact the phosphor layer 204R, 204G, 204B to give a potential, and each phosphor layer 204R, 204G, 204B. An Al metal back film 207 is formed on the surface so as to be in contact with the anode wiring 214. In addition, a black insulating layer 213 is formed between the phosphor layers 204R, 204G, and 204B and between the pixels to separate the light emitting portions and improve the display contrast.

Here, the planar shape of each of the phosphor layers 204R, 204G, and 204B is a rectangular shape, and the red light emitting phosphor layer 204R, the green light emitting phosphor layer 204G, and the blue light emitting fluorescence are formed so that the planar shape of one pixel is a square shape. The body layer 204B is arranged in this order in the short side direction. The phosphor used for these may be an electron beam-excited phosphor used for a color cathode ray tube or the like. For example, Y ₂ O ₃ : Eu is used for the red light emitting phosphor layer 204R, and ZnS: Cu is used for the green light emitting phosphor layer 204G. ZnS: Ag may be used for the blue light emitting phosphor layer 204B.

  Further, an anode electrode assembly 205 in which metal plate anodes 205b are arranged in a lattice shape is provided so as to surround each phosphor layer 204R, 204G, 204B. The anode electrode assembly 205 is in contact with the anode wiring 214 and connected to the Al metal back film 207, and a central metal plate anode 205 b is welded and fixed to the tip of the anode lead 210. The anode lead 210 is welded and fixed to the tip of an anode lead pin (not shown) inserted through the center of the back panel 208 through a through hole provided in the center of the cathode structure 206. The anode lead pin is fitted in the center of a plug 216 that is bonded and fixed to the outside of the back panel 208. The plug 216 is a connector for connecting to an external circuit, and a plurality of lead pins 209 connected to each electrode of the cathode assembly 206 are arranged around the anode lead pin.

  On the other hand, on the back panel 208, a cathode structure 206 in which electron emission portions are formed corresponding to the respective phosphor layers 204R, 204G, and 204B is disposed. The cathode structure 206 includes a ceramic substrate 206a, an electron emission portion including a back electrode 206b, a filament cathode 206c, and a grid housing 206d provided on the ceramic substrate 206a. And an electrode wiring 211 for connecting to a lead pin 209 inserted in a plug 216 arranged in the connector 216. The ceramic substrate 206a has a rectangular shape and is provided with a through-hole for passing the anode lead 210 in the center, and is bonded and fixed to the back panel 208 with a low melting point frit glass 215.

  The back electrode 206b is formed of a metal film having a rectangular planar shape disposed on the ceramic substrate 206a in a one-to-one correspondence with each phosphor layer 204R, 204G, 204B, and each back electrode 206b is the same. They are connected in the row direction by metal film wiring. An insulating film 212 is formed on the ceramic substrate 206a between the back electrodes 206b and on the metal film wiring. The filament cathode 206c is formed by applying an electron emitting material to a tungsten wire having a diameter of 7 to 20 μm, and a pair of filaments arranged in the column direction on the ceramic substrate 206a with the back electrode 206b interposed between the back electrodes 206b. It is fixed on the back electrode 206b at a predetermined interval by a support (not shown). As the electron emitting substance, for example, a so-called ternary oxide composed of barium oxide, calcium oxide, and strontium oxide is used.

  The grid housing 206d is a cap having a rectangular parallelepiped shape that covers the back electrode 206b and the filament cathode 206c together for one row, and is mounted on the ceramic substrate 206a for a predetermined number of rows. In this case, since one pixel column is composed of three phosphors of red, green, and blue, twelve grid housings 206d are mounted on this image tube having four pixel columns. These grid housings 206d are provided with rectangular openings 206f at portions facing the filament cathodes 206c, and project from the openings 206f to the filament cathodes 206c as shown in FIG. 9B. A groove-shaped mesh grid 206h is attached.

  The mesh grid 206h has a rectangular flat surface in which the bottom surface of the groove has a short side shorter than the short side of the opening 206f and a long side longer than the long side of the opening 206f. It is formed to become. Here, the grid housing 206d and the mesh-like grid 106h are both made of stainless steel, and the mesh-like grid 206h is welded to the inner surface of the grid housing 106d. Note that the outer shape of the grid housing 206d is not necessarily the same as long as the opening 206f and the mesh-like grid 206h are the same, and may be deformed as necessary.

  Further, the filament support and grid housing 206d for supporting the back electrode 206b and the filament cathode 206c are partially drawn out from the opening (not shown) provided in the ceramic substrate 206a to the lower surface of the ceramic substrate 206a. The corresponding electrode wirings 211 are respectively connected. These electrode wirings 211 pass through the low melting point frit glass 203 from between the back panel 208 and the frame-shaped side plate 201 and are drawn out of the vacuum vessel, and are connected to lead pins 209 fitted into the plugs 216.

The image tube configured as described above first applies a predetermined voltage from an external circuit to the filament cathode 206c to emit thermoelectrons, and supplies a high voltage of about 10 KV to the anode electrode assembly 205. The high voltage is applied to the Al metal back film 207. In such a state, if a positive voltage is applied to the grid housing 206d with respect to the filament cathode 206c and the voltage applied to the back electrode 206b is set to a negative potential with respect to the filament cathode 206c, the mesh of the grid housing 206d is set. An electron beam is emitted from the grid 206h, accelerated by the metal plate anode 205b, passes through the Al metal back film 207, and collides with the phosphor screen 204. Thereby, the fluorescent substance which comprises the fluorescent screen 204 is excited, and it light-emits with the luminescent color according to the fluorescent substance. This emitted light is transmitted through the front panel 202 and emitted from the front side to be displayed.

  Further, when the voltage applied to the back electrode 206b is set to a positive potential with respect to the filament cathode 206c, emission of the electron beam is suppressed, so that no light emission display is performed. Therefore, by controlling the voltage applied to the back electrode 206b, the current of the electron beam can be controlled to turn on / off the display pixels and adjust the luminance at the time of lighting. Therefore, the grid housings 206d in each column are sequentially provided. Scanning is performed so that a positive potential is applied, and by controlling the voltage applied to the back electrode 206b of each row, light emission of the pixels arranged in a matrix can be controlled to display a desired pattern. In this case, it goes without saying that the grid housing 206d that has not been selected suppresses unnecessary light emission as a negative potential with respect to the filament cathode 206c.

  In this embodiment, a rectangular opening 206f is provided in a portion facing the filament cathode 206c of the grid housing 206d corresponding to each of the rectangular phosphor layers 204R, 204G, 204B, and the filament is formed from the opening 206f side. A groove-shaped mesh grid 206h protruding toward the cathode 206c was attached. The mesh grid 206h has a rectangular flat surface in which the bottom surface of the groove has a short side shorter than the short side of the opening 206f and a long side longer than the long side of the opening 206f. It is comprised so that.

  As a result, as shown in FIG. 11, the equipotential surface 230 in the vicinity of the opening 206f is curved along the mesh grid 206h, so that electrons passing through the periphery away from the center line of the opening 206f The electron beam 231 is linearly converged on the phosphor screen 204 by being deflected in the direction of the center line of 206f. For this reason, the density of the electron beam 231 for exciting the phosphor is increased and the luminance is improved. Further, since the electron beam 231 converges in a linear shape, it is possible to prevent a leaky light emission of a phosphor display adjacent to the light emission display with good resolution. According to this embodiment, the degree of convergence of the electron beam 231 can be adjusted by changing the distance between the bottom surface of the mesh grid 206h and the opening 206f of the grid housing 206d and the slope of the slope of the mesh grid 206h.

Next, a second embodiment of the fluorescent display device according to the present invention will be described.
FIG. 12 is a partial cross-sectional view showing the configuration of an image tube according to the second embodiment of the present invention. In FIG. 12, the same reference numerals as those in FIG. 10 denote the same parts. This image tube is different from the image tube shown in the first embodiment in that a field emission type electron emission source using carbon nanotubes as an electron source is used for the electron emission portion of the cathode structure.

  The cathode assembly 206 includes a ceramic substrate 206a, an electron emission portion including a substrate electrode 221 provided on the ceramic substrate 206a, an electron emission layer 222, and a grid housing 206d. It is comprised from the electrode wiring 211 for connecting with the lead pin 209 inserted in the plug 216 arrange | positioned at the side. The ceramic substrate 206a has a rectangular shape and is provided with a through-hole for passing the anode lead 210 in the center, and is bonded and fixed to the back panel 208 with a low melting point frit glass 215.

  The substrate electrode 221 is formed by a conductive film having a rectangular planar shape arranged on the ceramic substrate 206a in a one-to-one correspondence with each phosphor layer 204R, 204G, 204B, and each substrate electrode 221 is the same. They are connected in the row direction by conductive film wiring. The conductive film is formed by screen-printing a conductive paste containing silver or carbon as a conductive material in a predetermined pattern on the ceramic substrate 206a so as to have a thickness of about 10 μm, and then firing. In this case, the substrate electrode 221 is not limited to the one formed by printing as described above, and may be composed of, for example, an aluminum thin film having a thickness of about 1 μm formed by using a known sputtering method and etching method. .

  In addition, an insulating film 212 is formed on the ceramic substrate 206a between the substrate electrodes 221 and on the wiring of the conductive film. The insulating film 212 is formed by screen-printing an insulating paste containing frit glass having a low melting point and then baking it. The electron emission layer 222 is composed of a conductive film including columnar graphite formed by aggregating a plurality of carbon nanotubes, and a paste in which columnar graphite is dispersed in a conductive viscous solution is screened on the substrate electrode 221. After printing, firing is performed, and then the surface is irradiated with laser to remove the conductive particles on the surface, the binder, and the carbon polyhedral particles in the columnar graphite by evaporation. The electron emission layer 222 has a thickness of 20 to 100 μm, and a large number of carbon nanotubes are uniformly distributed on the surface of the columnar graphite exposed from the conductive film, and each carbon nanotube operates as an electron emission source. In addition, as described in the third reference example, the columnar graphite may be processed so as to obtain a carbon nanotube having an open end.

  The grid housing 206d is a cap having a rectangular parallelepiped shape that covers the electron emission layers 222 in one row, and is mounted on the ceramic substrate 206a for a predetermined number of rows. Since the grid housing 206d has the same configuration as that of the first embodiment, description thereof is omitted. The substrate electrode 221 and the grid housing 206d are partly drawn from the opening (not shown) provided in the ceramic substrate 206a to the lower surface of the ceramic substrate 206a and connected to the corresponding electrode wiring 211 provided on the lower surface. ing. These electrode wirings 211 pass through the low melting point frit glass 203 from between the back panel 208 and the frame-shaped side plate 201 and are drawn out of the vacuum vessel, and are connected to lead pins 209 fitted into the plugs 216. Further, since the structure other than the cathode structure 206 is the same as that of the first embodiment, the description thereof is omitted.

  In the image tube configured in this manner, first, a high voltage of about 10 KV is supplied from the external circuit to the anode electrode assembly 205, and this high voltage is applied to the Al metal back film 207. In such a state, when a voltage of 300 to 500 V is applied to the grid housing 206d and the voltage applied to the substrate electrode 221 is 0 V or a negative voltage, the electron emission layer on the substrate electrode 221 intersecting with the grid housing 206d. Electrons are emitted from 222. The electrons emitted from the electron emission layer 222 are drawn out from the mesh grid 206h of the grid housing 206d, accelerated by the metal plate anode 205b, penetrate the Al metal back film 207, and collide with the phosphor screen 204. Is excited to emit light in an emission color corresponding to the phosphor. This emitted light is transmitted through the front panel 202 and emitted from the front side to be displayed.

  In addition, when the voltage applied to the substrate electrode 221 is set to an equipotential or positive potential with respect to the grid housing 206d, no electron beam is emitted, so that no light emission display is performed. Therefore, by controlling the voltage applied to the substrate electrode 221, the current of the electron beam can be controlled to turn on / off the display pixels and adjust the brightness at the time of lighting. Scanning is performed so that a predetermined positive voltage is applied, and by controlling the voltage applied to the substrate electrode 221 in each row, light emission of pixels arranged in a matrix can be controlled to display a desired pattern. . In this case, it goes without saying that the grid housing 206d that is not selected is set to 0 V or a negative voltage to suppress unnecessary light emission.

  Also in this embodiment, as shown in FIG. 13, the equipotential surface 230 in the vicinity of the opening 206f is curved so as to follow the mesh grid 206h, so that it passes through the periphery away from the center line of the opening 206f. Electrons are deflected in the direction of the center line of the opening 206f, and the electron beam 231 converges linearly on the phosphor screen 204. For this reason, the density of the electron beam 231 for exciting the phosphor is increased and the luminance is improved. In this embodiment, since the electron beam converges in a linear shape, the filament cathode is unnecessary in addition to the effect of enabling the prevention of leaking light emission of the bright phosphor display and the adjacent phosphor. Is simplified, and the assembly is simplified.

It is explanatory drawing which shows the structure of the 1st reference example. It is a figure explaining the effect | action of FIG. It is explanatory drawing which shows the structure of the 2nd reference example. It is a figure explaining the effect | action of FIG. It is explanatory drawing which shows the structure of the 3rd reference example. It is a figure explaining the effect | action of FIG. It is explanatory drawing which shows the structure of the 4th reference example. It is a figure explaining the effect | action of FIG. It is explanatory drawing which shows the structure of 1st Embodiment. It is a fragmentary sectional view which shows the structure of 1st Embodiment. It is a figure explaining the effect | action of FIG. It is a fragmentary sectional view showing the composition of a 2nd embodiment. It is a figure explaining the effect | action of FIG. It is explanatory drawing which shows the structure of the conventional image tube.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Glass bulb, 102 ... Face glass, 103, 203, 215 ... Low melting point frit glass, 104, 204 ... Phosphor screen, 105, 205 ... Anode electrode assembly, 105a ... Ring-shaped anode, 105b ... Cylindrical anode, 105c ... Ba getter, 106, 206 ... cathode structure, 106a, 206a ... ceramic substrate, 106b, 206b ... back electrode, 106c, 206c ... filament cathode, 106d, 206d ... grid housing, 106e, 106h, 206h ... mesh grid, 106f, 206f ... opening, 106i ... spacer, 106j ... filament support, 107, 207 ... Al metal back film, 107a ... contact piece, 108 ... stem glass, 108a ... exhaust pipe, 109a, 109b, 109c, 109d, 109e 109f, 209 ... lead pins, 110, 210 ... anode leads, 111b, 111c, 111d, 111e, 111f ... cathode leads, 121 ... columnar graphite, 121a ... carbon nanotubes, 122 ... conductive adhesive, 126, 221 ... substrate electrodes, 130, 230 ... equipotential surface, 131, 231 ... electron beam, 202 ... front panel, 201 ... side plate, 204B ... blue light emitting phosphor layer, 204G ... green light emitting phosphor layer, 204R ... red light emitting phosphor layer, 205b ... Metal plate anode, 208 ... back panel, 211 ... electrode wiring, 212 ... insulating film, 213 ... black insulating layer, 214 ... anode wiring, 216 ... plug, 222 ... electron emission layer.

Claims (6)

A display surface having at least one electron-emitting portion, an anode, and at least one control electrode disposed at a predetermined distance between the electron-emitting portion and the anode, and at least a part having a light-transmitting property And an envelope whose inside is evacuated,
A fluorescent display device comprising: at least one phosphor film that is applied to an inner wall of the envelope on the display surface side and is excited and emitted by collision of electrons emitted from the electron emission portion and accelerated by the anode electrode ,
The control electrode is
A metal member having an opening through which electrons emitted from the electron emission portion pass to the display surface side;
A metal mesh member disposed between the metal member and the electron emission portion so as to cover the opening, and electrically connected to the metal member;
The fluorescent display device, wherein the metal mesh member has a groove shape protruding from an opening of the metal member toward the electron emission portion.   2. The fluorescent display device according to claim 1, wherein the phosphor film has a rectangular shape, and the opening of the metal member has a shape that is long in the longitudinal direction of the phosphor film.   The fluorescent display device according to claim 1, wherein the electron emission portion is a filament cathode that emits thermoelectrons when energized and heated.   The fluorescent display device according to claim 1, wherein the electron emission portion is composed of carbon nanotubes.   The fluorescent display device according to claim 1, wherein the electron emission portion includes a carbon nanotube having an open end. 6. The fluorescent display device according to claim 1, wherein phosphor films having different emission colors are arranged adjacent to each other.

Images