JPH0831348A - Electrode structure of fluorescent character display tube - Google Patents

Abstract

PURPOSE:To connect a conductive layer as a grid with a grid wiring layer formed at different levels while a small area is used, simple works are required, and a high reliability is secured. CONSTITUTION:A fluorescent character display tube is structured so that rib is provided at the periphery of a phosphor layer and the second conductive layer as a grid is formed at the top of the rib, wherein a grid conduction layer 8 is formed from the second conductive layer. Further a rib 9a for pad having a closed shape is formed to constitute a pad part 9, and a grid wiring layer 16 is arranged on the rear surface of an insulative layer 2 in such a way as passing at least the position mating with the pad part 9, and a through hole 2a for confronting the grid conduction layer 8 to the front of the insulative layer 2 is furnished on the insulative layer 2 in a position inside of the rib 9a. A conductive paste 17 is poured in to the inside of the rib 9a, and thereby electric connection of the grid conduction layer 8 with the grid wiring layer 16 is generated through the hole 2a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent display tube in which a rib is formed around a phosphor layer, a conductive layer is formed on the top of the rib, and the conductive layer functions as a grid. Electrode structure.

[0002]

2. Description of the Related Art A fluorescent display tube displays a desired pattern by causing thermoelectrons emitted from a cathode to collide with a fluorescent material on the anode. A pattern design that is clear and easy to see, and is easy to perform multicolor display. It has excellent features such as a high degree of freedom and a low operating voltage, and is widely used as a display device for automobiles and audio equipment.

In such a fluorescent display tube, a triode structure having a grid arranged between a cathode and an anode is often used in order to control electrons emitted from the cathode. By applying a positive voltage to this grid,
The electrons emitted from the cathode are accelerated and diffused to be directed to the anode, or conversely, by applying a negative voltage, the electrons directed to the anode are blocked and the display is erased.

As this grid, for example, the actual exploitation 57
As described in JP-A-154059, JP-B-60-71063, JP-A-60-9040 and the like, mesh-shaped stainless steel plates are most often used.

However, since this mesh-shaped grid is a bridge-shaped one that is supported by several leg portions and is hollowly arranged so as to cover the anode, it may cause uneven brightness due to thermal deformation during driving. This causes problems such as short circuit due to contact with the anode or cathode. Therefore, in a fluorescent display tube using a mesh grid, the size of the grid and the driving voltage are significantly restricted.

Since the entire surface of the phosphor is covered with the mesh, a part of the emitted light is blocked by the body of the grid, which occupies about 8 to 15% of the grid area. It causes unevenness.

Further, when a positive voltage is applied to one of the grids arranged adjacently and a negative voltage is applied to the other grid, fluorescence under the grid to which the negative voltage is applied is near the boundary between both grids. A part of the electrons attracted to the grid, to which a positive voltage is applied, is taken into the body, causing leakage light emission. For this reason, in the conventional technique, it is impossible to perform grid division without leaking a portion having a dense pattern and causing light emission.

On the other hand, Japanese Utility Model Publication No. 3-52945 discloses that
There has been proposed a planar grid structure formed of a conductive material such as Al around the phosphor layer on the anode substrate.

According to the grid structure described in the publication, unlike the conventional grid made of a stainless steel plate, there is nothing that blocks the front surface of the phosphor, so that the shield reduces the amount of light, uneven brightness, and mesh grid. It is possible to solve various problems such as the problem of thermal expansion due to the provision of.

However, in this grid structure, since the grid is formed directly and planarly on the anode substrate, the protruding portion of the anode electrode below the phosphor is required in order to evenly emit light to the end of the phosphor. It is necessary to form a constant gap and to prevent a short circuit between the anode electrode and the grid. For this reason, it can be applied only to a sparse pattern in which the intervals between the segments are large, and the same problem as in the conventional mesh grid remains.

Further, since the grid surface is at the same level as or lower than the phosphor surface, the effect of diffusing the electrons emitted from the anode and blocking the electrons when a negative voltage is applied is poor. Therefore, the grid structure disclosed in Japanese Utility Model Laid-Open No. 3-52945 can be used only for static driving which does not require control by the grid.

Further, JP-A-61-29056 and JP-A-62-29050 describe that the grid surface is provided at a position higher than the phosphor surface. However, in the fluorescent display tube described in Japanese Patent Laid-Open No. 61-29056, since a plate-shaped grid is vertically erected on the anode substrate, the grid manufacturing process is complicated and the grid machine is complicated. There is a problem that the dynamic strength is reduced. Further, in the fluorescent display tube described in Japanese Patent Application Laid-Open No. 62-29050, the manufacturing process of the anode substrate is complicated by using a very advanced technique such as a photolithography method or thick film printing through a filling substance. Therefore, there is a problem that the cost becomes very high and it is almost impossible to mass-produce a product having stable quality.

Therefore, a grid structure of a fluorescent display tube having a novel structure for solving these problems was proposed by the present applicant and filed as Japanese Patent Application No. 5-37008 on February 25, 1993. Has been done.

In the structure of the fluorescent display tube described in the above-mentioned Japanese Patent Application No. 5-37008, a first conductive layer serving as an anode is formed on an insulating layer formed on an insulating substrate. A phosphor layer having a shape corresponding to the display pattern is formed on the first conductive layer, and a rib made of an insulating material having a height higher than that of the phosphor layer is formed around the phosphor layer. A second conductive layer to be a grid is formed on the top of the rib.

[0015]

[Patent Document 1] Japanese Patent Application No. 5-370
According to the structure described in the specification of No. 08, grid division can be performed in the pattern dense portion without causing leakage light emission, and electron acceleration and cutoff can be surely controlled.

In the previously proposed fluorescent display tube described above, the second conductive layer serving as the grid is formed on the top of the rib, whereas the grid wiring conductor for connecting the grid and the external circuit is not formed. Since the insulating layer is formed on the back surface, the two layers have different heights. For this reason, it is necessary to connect the second conductive layer to be the grid and the grid wiring conductor with some kind of conductor.

Generally, in such a case, a wide bonding pad is provided at an end of each wiring layer, and both bonding pads are connected by a bonding wire.

However, the connection between the bonding pad and the bonding wire requires the bonding wire to be pressure-bonded or welded to the bonding pad, which complicates the work and increases the number of work steps. Further, there is a problem in that the contact is poor between the bonding pad and the bonding wire and the bonding wire may be cut off, resulting in a lack of reliability.

It is also possible to use conductive paste to connect the ends of the respective wiring layers to each other. However, if the amount of conductive paste used is large, the conductive paste will reach areas other than the target area. There is a problem that it spreads and short-circuits with other electrodes. For this reason, conventionally, it is necessary to design the conductive paste with a margin in a spreading range, which causes a problem that a wasteful area is generated on the substrate. On the contrary, when the amount of the conductive paste used is small, there is a problem that connection failure occurs.

In addition, when the conductive paste is applied by using the technique of thick film printing, the conductive paste is formed at the target location using a plate. In this case, the back surface of the plate is Since it is pressed down by the squeegee, there is a problem in that the conductive paste cannot be uniformly applied due to the influence of the arrangement of the patterns already formed on the substrate. That is, when the conductive paste is attached in the vicinity of the place where the pattern is already formed, even when the back surface of the plate is pressed by the squeegee, the surface of the substrate and the surface of the plate are different due to the height of the existing pattern. There is a constant distance between them, and there is sufficient space for the conductive paste to adhere. Therefore, it is possible to sufficiently supply the target amount of the conductive paste. However, when attaching the conductive paste to a place away from the existing pattern,
When the back surface of the plate is pressed by the squeegee, the pressing force deforms the plate, and the surface of the substrate and the surface of the plate come close to each other. Therefore, it is not possible to secure a sufficient space for attaching a necessary amount of the conductive paste between the surface of the substrate and the surface of the plate,
The adhered amount may be insufficient. If the amount of conductive paste adhered is insufficient, connection failure will occur. In addition, if the gap between the surface of the substrate and the surface of the plate is narrow, if you try to forcefully inject a certain amount of conductive paste, it will not be possible to deposit in the direction perpendicular to the surface of the substrate. There is also a problem that the conductive paste spreads in a direction wider than the intended area in a direction parallel to the surface, and a short circuit occurs with other electrodes.

Therefore, according to the present invention, the conductive layer serving as a grid and the grid wiring conductors, which are respectively formed at different heights, are connected to each other in a small area with a simple operation and with high reliability. The purpose is to do.

[0022]

In order to solve the above problems, the present invention provides an insulating layer, a first conductive layer to be an anode, and a display pattern on an insulating substrate arranged facing a cathode. A phosphor layer having a shape to be sequentially stacked, a rib made of an insulating material having a height higher than that of the phosphor layer is formed around the phosphor layer, and a second grid serving as a grid is formed on the top of the rib. In the fluorescent display tube having the conductive layer, the third portion is provided on the top.
For forming a grid leading rib having the same height as the rib on which the conductive layer is formed, and a pad rib having the same height as the rib and having a closed shape in plan view, for grid connection. A pad is provided, a grid wiring conductor is provided on the back surface of the insulating layer so as to pass through at least a position corresponding to the grid connecting pad, and the third conductive layer is provided inside the pad rib. Is provided in the insulating layer, and a conductive paste is poured inside the pad ribs to electrically connect the third conductive layer and the grid wiring conductor to each other through the through hole. It is characterized by performing.

Further, according to the present invention, an insulating layer, a first conductive layer serving as an anode, and a phosphor layer having a shape corresponding to a display pattern are sequentially laminated on an insulating substrate arranged to face a cathode, In a fluorescent display tube in which a rib made of an insulating material having a height higher than that of the phosphor layer is formed around the phosphor layer, and a second conductive layer serving as a grid is formed on the top of the rib, 3. The rib for deriving the grid having the same height as the rib on which the conductive layer 3 is formed, the grid wiring conductor arranged on the back surface of the insulating layer, and the insulating layer for exposing the grid wiring conductor to the front side of the insulating layer. And a grid connection pad having a pad rib having the same height as the rib, which is arranged at a position sandwiching at least the through hole on the front side of the insulating layer, in the through hole portion. By the conductive paste is applied by thick film printing, and performing an electrical connection between said third conductive layer and the grid wiring conductor through said through hole.

[0024]

When the conductive paste is applied or poured into the inside of the pad rib, the third conductive layer connected to the second conductive layer to be the grid and the grid wiring conductor formed on the back surface of the insulating layer are formed. The spaces are electrically connected through the through holes formed in the insulating layer. At this time, since the pad rib has a closed shape in a plan view, the conductive paste does not spread outside the target area.

When the conductive paste is applied by thick film printing, since the pad ribs are formed at the positions sandwiching the through holes, the back surface of the plate for thick film printing is pressed by a squeegee. Even in such a case, the presence of the pad rib maintains a constant distance between the surface of the substrate and the surface of the plate, and there is a sufficient space for attaching the conductive paste. Therefore, regardless of the shape of the pattern formed on the substrate, the target amount of the conductive paste can be supplied at any place.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The features of the present invention will be specifically described below based on embodiments with reference to the drawings.

FIG. 1 is a schematic perspective view for explaining the basic structure of a fluorescent display tube to which the present invention is applied, FIG. 2 is a plan view of the same part, and FIG. 3 is a line AA of FIG. FIG.

With reference to FIGS. 1 to 3, 1 is an insulating substrate (anode substrate) made of glass, 2 is an insulating substrate formed on the insulating substrate 1 by a thick film printing method and made of a low melting point glass and a color pigment. It is a layer. A plurality of anode conductors 3 are provided to connect the first conductive layer 4 and the lead pins 13 through the through holes formed in the insulating layer 2. 16 is a grid wiring conductor, which is connected to the grid as described later. Reference numeral 6 is an insulating rib made of low melting glass formed by a thick film printing method.

This insulating rib is 10 to 3 in one printing.
A thickness of 0 μm is secured, and printing and drying are repeated 2 to 10 times to form the film. By dividing and printing in a plurality of steps in this way, it becomes possible to accurately form thin and high ribs vertically.

When forming the insulating rib,
JP-A-3-196441, Sakamoto et al .: "AS
screen-printing Process fo
rthe Fabrication of Plasma
a Display Panels ", Digest
of Technical Papers, 1994
Display Manufacturing Tec
hology Conference, pp. 127
-130, Atsumi et al .: "Printing Technology for Ultra-High-Definition Plasma Display Panels", 1989 IEICE Technical Report EID 89-7, pp. The printing techniques used to form barrier ribs in plasma display panels, such as those described in 69-71, can be applied.

On the top of the rib 6, a second aluminum film formed by thick film printing in the same pattern as the rib 6 is formed.
Conductive layer 7 is formed. The second conductive layer 7 is
It functions as a grid as described later. Inside the ribs 6, a first conductive layer 4 containing carbon is formed by a thick film printing method during the formation of the ribs 6, and a phosphor layer 5 is similarly formed on the upper surface by a thick film printing method. Are formed. In this embodiment, the rib thickness is 50 μm, and the protrusion amount from the upper surface of the phosphor layer is 100 μm.

Numeral 8 is a grid conductive layer for energizing the conductive layer 7 formed on the top of the rib 6. The grid conductive layer 8 is connected to a grid wiring conductor 16 formed on the back surface of the insulating layer 2 through a grid connecting pad 9 and a through hole formed in the insulating layer 2. The grid wiring conductor 16 extends along the back surface of the insulating layer 2 (see FIG. 3).

FIG. 4A is a plan view showing the detailed structure of the grid connection pad 9, and FIG. 4B is a plan view thereof.
FIG. 6 is a sectional view taken along line BB of FIG. The grid conductive layer 8 is shown in FIG.
As shown in (b), it is formed at the top of the grid leading rib 10 having the same height as the rib 6. The grid lead-out rib 10 and the grid conductive layer 8 are extended from the second conductive layer 7 serving as a grid to the grid connecting pad 9 (see FIG. 2). It is desirable to form two grid lead-out ribs 10 and grid conductive layers 8 in parallel as shown in FIG. 4A to prevent disconnection. Also,
The grid lead-out rib 10 and the grid conductive layer 8 are preferably 1.5 to 2 times as wide as the width of the second conductive layer 7 serving as a grid.

The grid connection pad 9 is a rectangular frame-shaped rib 9a including the grid lead-out rib 10 and the ends 10a, 8a of the grid conductive layer 8 inside, and the conductive layer 9b formed on the top of the rib 9a. It consists of and. In addition,
The shape of the rib 9a is not limited to the rectangular frame shape, but has a closed shape in plan view, and may have any shape as long as it is. A through hole 2a is formed in the insulating layer 2 at approximately the center of the rectangular frame-shaped rib 9a. A grid wiring conductor 16 is formed on the back surface of the insulating layer 2 by a thick film printing method, and a part of the grid wiring conductor 16 faces the through hole 2a. At this time, the end portion 8a of the grid conductive layer 8 is positioned substantially at the end portion of the through hole 2a. The grid wiring conductor 16 extends along the back surface of the insulating layer 2 and is connected to the lead pin lead-out pad 11 (see FIG. 2) via the wiring conductor 3.

In the grid connection pad 9, the conductive paste 17 is applied to the grid conductive layer 8 inside the rectangular frame-shaped rib 9a using a dispenser (not shown).
Then, the conductive paste 17 electrically connects the end portion 8a of the grid conductive layer 8 and the other end portion of the grid wiring conductor 16 by way of the through hole 2a. As the conductive paste 17, for example, one made of carbon, aluminum, nickel or the like is used.

At this time, the end portion 8a of the grid conductive layer 8
Is surrounded by the rectangular frame-shaped rib 9a, the conductive paste 17 does not spread outside the rib 9a, and a short circuit does not occur with other electrodes. Further, since the area where the conductive paste 17 spreads can be defined in advance, it is not necessary to provide a margin in the area, and the grid conductive layer 8 and the grid wiring conductor 16 can be connected in a small area. In addition, the grid conductive layer 8 and the grid wiring conductor 1
Since the connection with 6 is made by the conductive paste 17 which is a fluid at the beginning of pouring, the contact between the grid conductive layer 8 and the conductive paste 17 and the conductive paste 1
The contact between the wiring 7 and the grid wiring conductor 16 is made over a large area, and the electrical and mechanical connection is ensured. In addition, the work itself is conductive paste 17
Since it is only poured, the work becomes easy.

FIG. 5 is a perspective view showing the grid connection pad 9 before the conductive paste 17 is poured, and FIG.
FIG. 6 is a perspective view showing the grid connection pad 9 after the conductive paste 17 is poured.

In the above-described embodiment, the dispenser (not shown) is used to pour the conductive paste 17 into the inside of the rib 9a having a rectangular frame shape, but the conductive paste 17 is formed by thick film printing. It may be applied.

In this case, a plate having a hole at a position corresponding to the grid connection pad 9 is used, and the conductive paste is poured into the grid connection pad 9 by pressing it with a squeegee from the back surface of the plate. , In this case, since the pad ribs are formed surrounding the through hole, even if the back surface of the plate for thick film printing is pressed by the squeegee, the presence of the pad ribs causes A certain distance is maintained between the plate surface and the plate surface, and there is sufficient space for attaching the conductive paste. Therefore, regardless of the shape of the pattern formed on the substrate, the target amount of the conductive paste can be supplied at any place. Even in the case of thick film printing, the conductive paste flows down in a flowing state to some extent. It is possible to prevent the conductive paste from spreading more than necessary.
Therefore, in any case, it is highly desirable that the pad rib has a closed shape.

[0040]

According to the present invention, the following effects can be obtained.

(1) Between two conductive layers having different heights,
It is possible to connect with a simple structure and work with high reliability.

(2) Since the conductive paste does not flow outside the predetermined range, the area required for connection can be reduced.

(3) Since the distance between the substrate and the plate is kept constant, the two conductive layers can be surely connected without being affected by the shape of the printing pattern.

[Brief description of drawings]

FIG. 1 is a schematic perspective view for explaining a basic configuration of a fluorescent display tube to which the present invention is applied.

FIG. 2 is a plan view of a main part of the fluorescent display tube shown in FIG.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is an enlarged view of a main part of a fluorescent display tube to which the electrode structure of the present invention is applied. The figure (a) is a top view and the figure (b) is the BB sectional drawing of the figure (a).

FIG. 5 is a perspective view showing a grid connection pad before pouring a conductive paste.

FIG. 6 is a perspective view showing a grid connection pad after pouring a conductive paste.

[Explanation of symbols]

1 ... Insulating substrate (anode substrate), 2 ... Insulating layer, 3 ... Wiring conductor, 4 ... First conductive layer (anode), 5 ... Phosphor layer, 6 ... Rib, 7 ... Second conductive layer (grid) , 8 ... Grid conductive layer, 9 ... Grid connecting pad, 10 ... Grid lead-out rib, 11 ... Lead pin extracting pad, 12 ... Filament, 13 ... Lead pin, 14 ... Filament supporting frame, 15 ... Cover glass, 16 ... Grid Wiring conductor, 17 ... Conductive paste

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Tomiya 2160, Yatsunami, Nanami, Yasu Town, Asakura-gun, Fukuoka Prefecture, Kyushu Noritake Co., Ltd.

Claims (3)

[Claims] 1. A phosphor layer having an insulating layer, a first conductive layer serving as an anode, and a phosphor layer having a shape corresponding to a display pattern are sequentially laminated on an insulating substrate arranged to face a cathode, and the phosphor layer is formed. In a fluorescent display tube in which a rib made of an insulating material having a height higher than that of the phosphor layer is formed around and a second conductive layer serving as a grid is formed on the top of the rib, a third conductive layer is formed on the top. A grid connecting pad is formed by forming a grid lead-out rib having the same height as the layer-formed rib and a pad rib having the same height as the rib and having a closed shape when seen in a plan view. A grid wiring conductor is provided on the back surface of the insulating layer so as to pass through at least a position corresponding to the grid connection pad, and the third conductive layer is provided on the front side of the insulating layer inside the pad rib. Through hole The fluorescent material characterized in that the third conductive layer and the grid wiring conductor are electrically connected through the through hole by providing the conductive paste inside the insulating layer and filling the inside of the pad rib. Display tube electrode structure. 2. An insulating layer, a first conductive layer serving as an anode, and a phosphor layer having a shape corresponding to a display pattern are sequentially laminated on an insulating substrate arranged to face the cathode, and the phosphor layer is formed. In a fluorescent display tube in which a rib made of an insulating material having a height higher than that of the phosphor layer is formed around and a second conductive layer serving as a grid is formed on the top of the rib, a third conductive layer is formed on the top. The grid lead-out rib having the same height as the rib forming the layer, the grid wiring conductor disposed on the back surface of the insulating layer, and the through hole of the insulating layer that exposes the grid wiring conductor to the front side of the insulating layer. And a grid connection pad having a pad rib having the same height as the rib, which is arranged at a position sandwiching at least the through hole on the front side of the insulating layer, and a conductive paste is provided in the through hole portion. By applying a thick film printing, the third electrode structure of the fluorescent display tube of the electrical connection and performing through the through hole of the conductive layer and the grid interconnection conductor. 3. The electrode structure of the fluorescent display tube according to claim 2, wherein the pad rib of the grid connecting pad has a closed shape when seen in a plan view.