JP2001307666A - Fluorescent display tube and driving method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluorescent display tube having thin-film flat grids capable of optionally and easily setting a height of a phosphor layer with respect to the grid, and of preventing a shading phenomenon of electrons by reducing charging-up in an insulation layer. SOLUTION: A first substrate S1 has recessed parts comprising tapers Ts and bottoms Bs, and thin-film anode electrodes A1 to An having stripe shapes are formed on an upper surface of the first substrate S1 including the recessed parts. Thin-film grids G1 to G7 having stripe shapes are formed in matrix thereon with a thin-film insulation layer D therebetween. The insulation layer D and each of the grids G1 to G7 have opening parts Od, Og on the bottom of the recessed parts (Kg is a recessed part of the grid) corresponding to the recessed parts of the first substrate S1, wherein phosphors H11 to H7n are coated on the anode electrodes A1 to An which are exposed inside the opening parts. The height of the phosphors H11 to H7n is approximately equal to or higher than that of the grids G1 to G7. The relation of this height can be optionally set by adjusting the depth of the recessed parts of the first substrate S1. Each of the grids G1 to G7 has a taper Tg at a recessed part Kg.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a fluorescent display tube using a flat grid and a driving method thereof.

[0002]

2. Description of the Related Art FIG. 10 shows a plan view and a sectional view of a part of an anode electrode side substrate of a conventional fluorescent display tube using a flat grid. 10 (b) and 10 (c) show enlarged cross-sectional views of a part in the direction of arrow X in FIG. 10 (a). FIG. 10 (b) and FIG. ing. S1 is
A plurality of striped anode electrodes A1 to Am are formed on a glass substrate on the anode electrode side, and the anode electrodes A
A solid insulating layer D is formed on 1 to Am, and grids G1 to G7 are formed on the insulating layer D. The anode electrodes A1 to Am and the grids G1 to G7 are arranged in a matrix. Grids G1 to G7 and insulating layer D
Is formed with a rectangular opening, and the phosphors H11 to H7m are applied on the anode electrode in the opening. Anode electrodes A1 to Am, grids G1 to G7, phosphor H
11 to H7m and the insulating layer D are thick films formed by printing.

In the case of FIG. 10 (b), the phosphor H21 is formed at the same height as the insulating layer D. In the case of FIG. 10 (c), the phosphor H21 is located at a position lower than the insulating layer D. Is formed. The filament not shown is stretched above the grids G1 to G7 (on the side opposite to the anode electrode). (See, for example, Japanese Utility Model Laid-Open No. 63-69354).

[0004]

Since the grid has a function of extracting electrons emitted from the filament to the anode electrode, it is necessary to arrange the grid closer to the filament than the anode electrode. In both cases of FIGS. 10B and 10C, the grids G2 and G3 are composed of the phosphors H21 and H21.
It is arranged at a position higher than 31 (closer to the filament). As a result, in the case of FIG. 10B, some of the electrons emitted from the filament to the anode electrode A1 collide with the exposed surface Ds1 of the insulating layer D and are charged up. In the case of FIG. 10 (c), it collides with the exposed surface Ds2 of the insulating layer D and charges up.

In the cases shown in FIGS. 10B and 10C, for example, the electrons arriving at the end of the phosphor H21 are repelled by this charged-up charge and cannot reach the phosphor H21. A peeling phenomenon occurs, and as a result, a portion that does not emit light occurs at the end of the phosphor H21.
The same applies to the phosphor H31. The effect of this electron eclipse phenomenon becomes greater as the width of the anode electrode and the grid decreases and the distance between them decreases. That is,
The higher the definition of the fluorescent display tube, the greater the effect of the electron eclipse phenomenon and the lower the display quality.

Further, the conventional fluorescent display tube has grids G1 to G1.
Since G7 and the insulating layer D are formed of a thick film, for example, the thickness of the insulating layer D is limited to about 0.2 mm. Therefore, it is difficult to increase the definition of the fluorescent display tube with a thick film. It is. Further, when the openings are formed in the grids G1 to G7, if the shape of the openings is as shown in FIG. 10A, a bridge cannot be provided on the mask for forming the openings.
Virtually no mask deposition can be employed.

[0007] Further, since the filament of the fluorescent display tube is stretched at a predetermined interval, the amount of emitted electrons is different between a portion where the anode electrode is close to the filament and a portion which is far from the filament. A difference in light emission luminance (luminance unevenness) occurs. In order to solve these problems, the present applicant has formed a grid, an anode electrode, an insulating layer, and the like of a flat grid type fluorescent display tube with a thin film, and set the grid to substantially the same height as the phosphor, Also filed an application for the invention to be arranged at a lower position (see Japanese Patent Application No. 2000-79237). By the way, the diameter of the phosphor particles generally used in the fluorescent display tube is about 2 to 3 μm, and the phosphor layer is formed by overlapping at least 2 to 3 phosphor particles in relation to the emission luminance. It is desirable to have a thickness of For example, assuming that the thickness of the phosphor layer is equivalent to three phosphor particles, the thickness is 6 to 9
It becomes about μm. On the other hand, the thicknesses of the anode electrode, the grid, and the insulating layer are each about 1 μm in the case of a thin film. Therefore, when an insulating layer and a grid are formed on the anode electrode and a phosphor is applied on the insulating layer and the anode electrode at the opening of the grid, the phosphor layer becomes higher than the grid, and the phosphor layer becomes higher. It is not easy to make the height of the grid equal to that of the grid.

In view of the above, an object of the present invention is to provide a fluorescent display tube having a structure in which the height of the phosphor layer and the grid can be easily formed to the same level. It is a further object of the present invention to provide a high-definition fluorescent display tube in which the charge-up of the insulating layer is small, electrons emitted from the filament are uniformly diffused in a plane, and luminance unevenness is small. Another object of the present invention is to form a grid of a fluorescent display tube by mask evaporation.

[0009]

The fluorescent display tube of the present invention has a stripe-shaped anode electrode and a stripe-shaped grid formed in a matrix with an insulating layer interposed therebetween. An opening is formed in the insulating layer and the grid, and a phosphor is applied on the anode electrode in the opening between the first substrate and the second substrate facing the first substrate (including on the second substrate). A cathode is arranged, and a recess for accommodating at least the phosphor is formed in the first substrate. In the fluorescent display tube of the present invention, a taper is formed on an inner surface of the concave portion of the first substrate. The insulating layer and the grid of the fluorescent display tube of the present invention have a concave portion stacked along the inner surface of the concave portion of the first substrate. In the fluorescent display tube of the present invention, a taper is formed on the inner surface of the concave portion of the grid. In the fluorescent display tube of the present invention, the surface of the phosphor is arranged on the cathode side with respect to the surface of the grid in contact with the insulating layer. In the fluorescent display tube of the present invention, the surface of the first substrate opposite to the surface on which the concave portion is formed is a rough surface. In the fluorescent display tube of the present invention, a striped back electrode is formed on the second substrate. The fluorescent display tube of the present invention is provided with a means for setting a potential gradient to the filament selection voltage applied to the back electrode.

The fluorescent display tube of the present invention is driven so as to select a filament from which electrons are emitted by applying a filament selection voltage and a filament non-selection voltage in a time division manner to each filament control group of the back electrode. . The fluorescent display tube of the present invention is driven so that a filament selection voltage and a filament non-selection voltage are applied to the filament in a time-division manner to select a filament that emits electrons. The fluorescent display tube of the present invention is driven by providing a potential gradient to the filament selection voltage. The fluorescent display tube of the present invention is driven so that a grid selection voltage is applied to the grid in a time-division manner, and a data signal is input to the anode electrode to select a phosphor to emit light.

[0011]

1 and 2 show a plan view and a sectional view of a part of a fluorescent display tube according to an embodiment of the present invention. 1 is a plan view of the first substrate, FIG. 2A is an enlarged cross-sectional view in the direction of arrow B in FIG. 1, and FIG. 2B is an enlarged cross-sectional view in the direction of arrow A in FIG. Shown respectively.

First, in FIG. 1, S1 is a first glass substrate, A1 to An are striped thin film anode electrodes,
, H71 to H7n are phosphors, G1 to G
Reference numeral 7 denotes a striped thin-film grid having a concave portion having an opening at the bottom. The anode electrodes A1 to An and the grids G1 to G7 are arranged in a matrix, and the phosphors H11 to H7
n is applied. The width of the anode electrodes A1 to An is
125 μm, the interval between the anode electrodes A1 to An is 125
μm.

Next, according to the enlarged view of FIG. 2, the first substrate S1, the anode electrodes A1 to An, the grids G1 to G1 of this embodiment are shown.
The detailed structure of G7, insulating layer D, and phosphors H11 to H7n will be described. Note that FIG. 2 shows only a part of the anode electrode and the like, but parts that are not shown are the same as in FIG.

The first substrate S1 has phosphors H51, H5
2, a recess is formed at a location corresponding to H61. The recess has a taper Ts and a bottom Bs. As shown in FIG. 2B, the anode electrode A1 is formed in a stripe shape on the surface including the concave portion of the first substrate S1. An insulating layer D is formed on the anode electrodes A1 and A2, and grids G5 and G6 are formed thereon in a stripe shape. The grids G5, G6 and the insulating layer D have recesses of the same shape as the recesses of the first substrate S1, and openings Og, Od are formed at the bottoms of the grids G5, G6 and the recesses of the insulating layer D, respectively. ing. A taper Tg is formed on the inner periphery of the concave portion Kg of the grids G5 and G6. Also in the concave portion of the insulating layer D, like the taper Tg of the grids G5 and G6, the first
A taper is formed along the taper Ts of the substrate S1. Openings Og, O of grids G5, G6 and insulating layer D
In d, a part of the anode electrodes A1 and A2 is exposed, and the exposed portions are coated with the phosphors H51, H52 and H61.

In the case of FIG. 2, the phosphors H51, H52, H6
1 is located at substantially the same height as the grids G5 and G6, the electrons emitted from the filament are
1. Focus on H52 and H61. Therefore, the charge-up of the insulating layer D is reduced, and the phenomenon of electron eclipsing is also reduced. Although the heights of the phosphors H51, H52, H61 and the grids G5, G6 in FIG. 2 are almost the same, the height of the phosphor may be higher than that of the grid. Body H51, H52, H61
And the charge-up of the insulating layer D is further reduced.

The grids G5 and G6 in FIG. 2 have a taper Tg in the concave portion Kg, so that the cutoff characteristics are improved.
In addition, since the exposed surface of the insulating layer D becomes smaller, the charge-up of electrons also becomes smaller. Since the insulating layer D of the present embodiment is a thin film, the film thickness of the insulating layer D is 1 in the case of a conventional thick film.
The charge can be reduced to 1/0 or less, and the charge-up of electrons is reduced from this point as well.

In this embodiment, the thickness of the anode electrode, the grid, the insulating layer and the phosphor and the thickness of the first substrate S1
The height of the grid and the phosphor can be arbitrarily selected by appropriately selecting the depth of the concave portion. Note that since the height of the grid and the phosphor is related to the depth of the concave portion of the first substrate S1, the taper Ts is not necessary from the viewpoint of the height adjustment, but the cut-off characteristic of the grid is not required. From the viewpoint of improvement and reduction of the charge-up of the insulating layer, it is desirable to provide them. Further, in the present embodiment, the description has been given of the case where the concave portion of the first substrate S1 is formed in a rectangular shape at the intersection of the grid and the anode electrode. However, the concave portion is formed in the stripe-shaped groove for each stripe-shaped anode electrode. Can also. In this case, since the concave portion Kg of the grid has no side perpendicular to the anode electrode or has a side that is lower than that of the phosphor, the cutoff characteristic of the grid is slightly inferior, but there is no practical problem.

FIG. 3 shows a concave portion (FIG. 2) of the grid according to the present invention.
(Kg) of FIG. A is an anode electrode, D is an insulating layer, G is a grid, Tg is a taper of a concave portion of the grid, and H is a phosphor. The phosphor H is shown in FIG.
In the same manner as described above, the grid G and the insulating layer D are formed in the openings of the concave portions. In the case of FIG. 3A, the concave portion of the grid G is
1 is similar to FIG. 1, but in the case of FIG. 3B, a notch C is formed in a part of the rectangular recess. Notch C
May extend over one side of the rectangle. In addition, the cutouts C may be formed at two locations above and below the rectangular recess. The opening of the concave portion of the grid G is shown in FIG.
In the case of (1), it is formed by a photolithography method, but in the case of FIG. 3B, a bridge can be provided on the evaporation mask by using the cutout portion C. it can.

In FIGS. 1 to 3, the opening of the concave portion of the grid and the insulating layer has been described as having a square shape, but may have other shapes such as a polygon and a circle. Note that the insulating layer D in FIGS. 2 and 3 also has the function of a black matrix, so that it is not necessary to separately provide a black matrix. In addition, the invention relating to the first substrate S1 described with reference to FIGS. 1 to 3 combines the height of the grids G1 to G7 with the phosphors H11 to H11 by combining with the back electrode described with reference to FIGS.
Even if it is about the same or lower than H7n,
Since the back electrode supplements the control action of the electrons of the grids G1 to G7, both can reliably control the electrons emitted from the filament to the anode electrode.

FIG. 4 shows a process for forming the first substrate S1 and the anode electrode and the like in FIGS. First, a resist pattern is formed on the glass substrate S (plate thickness 1.1 mm) of (1) by a photolithographic method, and has a taper Ts as shown in (2) using BHF (buffered hydrofluoric acid). A recess Ks is formed. The concave portion Ks is several μm to several tens μm.
m to a depth of m. In this embodiment, the thickness is 10 μm. The taper Ts has a horizontal length of 10 μm.
Is formed at an angle which rises by 10 μm. Note that a rough surface P is formed on the surface of the glass substrate S opposite to the surface on which the concave portion Ks is formed. The rough surface P is a non-reflective surface.

A metal film such as ITO (compound of indium and tin) or Al (aluminum) is formed on the upper surface of the glass substrate S including the concave portion Ks by sputtering or EB vapor deposition to form a metal film for an anode electrode. By patterning by the method, a striped anode electrode A is formed as shown in (3). At this time, the anode electrode A was formed simultaneously with the formation of the anode electrode metal film using a deposition mask.
Can also be formed. Here, Ka is a concave portion of the anode electrode, and Ta is a taper of the concave portion. The thickness of the anode electrode A may be in the range of 0.1 μm to several μm, but is selected to be 0.5 μm in the present embodiment. The thickness of the anode electrode A is selected in consideration of the resistivity of the metal material used, the wiring pattern, the depth of the concave portion Ks, and the like. The material of the anode electrode is ITO or Al when the fluorescent display tube is of a direct-view type, that is, a type in which the light emission of the phosphor is directly observed.
And any other metal such as a transmission type (FL type),
In the case of a type for observing the light emission of the phosphor from the substrate S side, IT
O is used. In the case of the direct view type, the rough surface P is not formed.

On the striped anode electrode A,
As shown in (4), SiOx (silicon oxide) is CVD (C
chemical Vapor Deposition)
An insulating layer D is formed by using a photolithography method, and by chemical etching or RIE dry etching, etc.
An opening Od of 120 μm square is formed in the concave portion Kd. Here, Td is the taper of the concave portion Kd. The anode O is exposed at the opening Od. The thickness of the insulating layer D is
The range may be from 0.01 μm to several μm, but in the present embodiment, it is selected to be 1.0 μm.

On the insulating layer D, an aluminum (Al) film is formed by covering the opening Od with a vapor deposition mask, and (5)
The grid G is formed as shown in FIG. Kg is a concave portion of the grid G, Tg is a taper of the concave portion, and Og is an opening.
An opening Og is formed in the grid G simultaneously with the film formation. The thickness of the grid G may be in the range of 0.01 μm to several tens of μm, but is selected to be 1.0 μm in the present embodiment. A phosphor layer H is formed on the insulating layer D and the anode electrode A exposed at the openings Od and Og of the grid G by a slurry method as shown in (6).

Next, a driving method of the fluorescent display tube according to the embodiment of the present invention will be described. FIG. 5 shows a first substrate S1 on which an anode electrode, an insulating layer, and a grid having the same structure as FIGS. 1 to 3 are formed, and a second substrate S on which back electrodes B1 to B9 are formed.
2 and 3 are a plan view and a cross-sectional view of a fluorescent display tube in which No. 2 is combined. FIG. 5A is a cross-sectional view, and FIG. 5B is a plan view in the direction of the arrow Y in FIG. F1 and F2 are filaments serving as cathodes and are stretched in the longitudinal direction of the grids G1 to G7. The back electrodes B1 to B9 are connected to the filaments F1, F
2 so that the filaments F1 and F2 can be easily controlled.
Along the longitudinal direction of the grids G1 to G7 (direction intersecting the anode electrodes).

First, the operation of the back electrodes B1 to B9 will be described. For the back electrodes B1 to B9,-several tens of volts to + several tens of volts
Is applied to control the emission of electrons emitted from the filaments F1 and F2 to the anode electrodes A1 to An (only A1 is shown in FIG. 5) and stop emission of electrons. Back electrode B1
Of the B9, the back electrodes B1 to B5 are filament F
1 and the back electrodes B5 to B9 control the filament F2 in groups. For example, when the filament F1 is an electron emission filament and the filament F2 is an electron emission stop filament, a positive control voltage is applied to the back electrodes B1 to B5 as a filament selection voltage, and the back electrode B6
To B9, a negative control voltage is applied as a filament non-selection voltage (the emission of electrons from the filament is stopped by covering the filament F2 with a negative potential). The filament selection voltage and the filament non-selection voltage are as follows: filament potential (0 V in this case) to +10 V, and −10 V to filament potential (0 in this case).
V).

When the filament selection voltages applied to the back electrodes B1 to B9 are the same, for example, when the filament F1 and the anode electrode A1 are viewed, the fluorescent material H21 close to the filament F1, H
31 and the phosphors H11 and H41 on both sides thereof have different distances to the filament F1, so that the amount of electrons emitted to the phosphors is different and the emission luminance is different. Therefore, the present invention is devised so that electrons emitted from the linear filament are emitted substantially uniformly in a planar manner by providing a potential gradient to the control voltage applied to the back electrodes B1 to B9. .

FIG. 5B shows the state of the potential gradient of the control voltage applied to the back electrodes B1 to B9.
1 indicates a selected state. In FIG. 5B, 0V is applied to the back electrode B3 closest to the filament F1, 2V is applied to the back electrodes B2 and B4 on both sides, and 4V is applied to B1 and B5. By thus providing a potential gradient to the control voltage applied to the back electrode, electrons emitted from the filament can be uniformly and planarly diffused in a region including both sides of the filament. The invention of the back electrode of FIG. 5 can also be applied to a conventional fluorescent display tube.

Next, a method for directly selecting a filament according to the embodiment of the present invention will be described with reference to FIG. FIG. 6A shows the same sectional view as FIG. 5A, and FIG.
Shows a plan view in the direction of arrow C in FIG.

In the example of FIG. 6, the filament that emits electrons is selected depending on whether the voltage applied to the filament is negative or positive. For example, when a negative filament selection voltage is applied to the filament F1 and a positive filament non-selection is applied to the filament F2, the filament F1 can emit electrons, but the filament F2 cannot emit electrons. State.

FIG. 6B shows a state in which a negative filament selection voltage is applied to the filament F1 and a positive filament non-selection voltage is applied to the filament F2. In this state, since the phosphors H11 to H4n can receive electron emission from the filament F1, they belong to the range where light emission is possible, but the phosphors H51 to H7n cannot receive electron emission from the filament F2. From the range where light emission is impossible. By applying the filament selection voltage to the filament F1 or the filament F2 as described above, it is possible to select a range in which the phosphors H11 to H7n can emit light. In this example, the phosphor H41 located between the filaments F1 and F2 is located at a position to receive the electron emission from both the filaments F1 and F2, and is overlapped with the phosphor at another position by overlapping the scan timing. The light emission luminance can be made the same, and the light emission luminance of each phosphor can be made uniform.

The direct selection method of the filament shown in FIG. 6 is used in combination with the method of applying a control voltage having a potential gradient to the back electrode shown in FIG. The emitted electrons can be uniformly and planarly diffused.

As described above, according to the present invention, the filament which emits electrons to the anode electrode is selected by the filament selection voltage applied to the back electrode or the filament selection voltage applied to the filament, and at the same time, the potential gradient is applied to the filament selection voltage. Is set to make the electrons emitted to the anode electrode uniform.

For the selection of the anode electrode and the grid, a selection method used in a conventional fluorescent display tube in which the anode electrode and the grid are arranged in a matrix can be used. For example, in the grids G1 to G7, a time division
A voltage of V to + several tens of volts (a voltage higher than the filament potential and lower than the anode potential (e.g., + several volts) on the selected grid, and a voltage less than the filament potential (e.g.-several tens of volts) on the non-selected grid) are sequentially applied; By inputting a data signal of + several tens of volts to the anode electrodes A1 to An, a predetermined phosphor can be selected from the phosphors H11 to H7n to emit light.

FIG. 7 shows an embodiment of a filament selection circuit used in the direct filament selection method of FIG. Circuits related to the anode electrode A, the grid G, and the back electrode B are schematically illustrated, and a data writing circuit, a grid scan circuit, a control voltage application circuit, and the like are omitted. An AC filament voltage is applied to the filaments F1 and F2 from the secondary coils Ef1 and Ef2 of the transformer T.

The center taps Ek1 and Ek2 of the secondary coils Ef1 and Ef2 are connected to the power supply Eb via the resistors Rs and Rs.
And the switching elements Tr1, Tr
2 is grounded. The On / Off signal of the input terminal Ti is supplied directly to the switching element Tr1, and is supplied to the switching element Tr2 via a knot circuit. When the signal at the input terminal Ti is an On signal, the switching element Tr1 conducts and the secondary coil Ef
1 center tap Ek1 is grounded, and filament F1
Is applied with a ground potential. On the other hand, switching element Tr
2 is turned off because the On signal is inverted and the Off signal is supplied. Therefore, the center tap Ek
2 is connected to the power supply Eb, and the voltage of the same power supply is applied to the filament F2. When the signal of the input terminal Ti is Off
In the case of a signal, the conduction state of the switching elements Tr1 and Tr2 is opposite to the above, the ground potential is applied to the filament F2, and the voltage of the power supply Eb is applied to the filament F1. Thus, by continuously supplying the On / Off signal to the input terminal Ti, the filament F1 or the filament F2 can be selected in a time-division manner.

The circuit for switching or selecting the filament is not limited to the circuit shown in FIG. 7, but may be any circuit capable of alternately applying a positive voltage and a negative voltage to the filament F1 and the filament F2. FIG. 8 is a cross-sectional view of a model fluorescent display tube of an electric field analysis simulation performed to confirm the effect of the potential gradient of the control voltage applied to the back electrode according to the embodiment of the present invention. The model fluorescent display tube has the same structure as the fluorescent display tubes of FIGS. S1 is a first substrate, S2 is a second substrate, A1 is an anode electrode, G1 to G7 are grids, B1 to B9 are back electrodes,
F1 and F2 are filaments, and D is an insulating layer.

In the model fluorescent display tube, the first substrate S1
The distance between the second substrate S2 and the rear electrode B is 0.86 mm.
The distance between 1 to B9 and the filaments F1 and F2 is 0.1
5 mm, the distance between the filaments F1 and F2 and the anode electrode A1 is 0.7 mm, the distance between the filaments F1 and F2 is 2.0 mm, the voltage applied to the anode electrode A1 is 12.0 V, and the filament F1 F
The voltage applied to 2 is 0V. Also, grid G1
Of G7, +6 V is applied to a selected grid and -6 V is applied to a non-selected grid. FIG. 9 shows a simulation result of the model fluorescent display tube of FIG. FIG.
Due to the difference in the control voltage applied to the back electrodes B1 to B9,
It shows how the distribution of the current density of the anode electrode A1 and the back electrodes B1 to B9 changes. FIG. 9 (a)
9 shows the result when the potential gradient is provided in the control voltage applied to the back electrode, and FIG. 9B shows the result when the potential gradient is not provided in the control voltage.

In FIG. 9, the horizontal axis represents the first substrate S of FIG.
1 indicates a lateral distance (Distance), and 1.00 is -1.00 between the filament F1 and the filament F2.
Corresponds to the left end of the anode electrode A1, and 3.00 corresponds to the right end of the anode electrode A1. The vertical axis indicates the current density (Ip) of the anode electrode and the current density (Iback) of the back electrode.

FIG. 9A shows a case where a potential gradient is provided to the control voltage (Eback) applied to the back electrodes B1 to B9 as in FIG. 5, and the control voltages are (0V, 2V, 4V) and (0V).
V, 3V, and 6V) are shown. 0 V is applied to the back electrodes B3 and B7.
2V and 3V are the back electrodes B2, B4, B6, B8
And 4V and 6V are applied to the back electrodes B1, B5 and B9. FIG. 9B shows that the control voltage (Eback) is 0V and 3V.
The results of a simulation performed for two cases with V (no potential gradient) are shown.

In the case of FIG. 9A, in each case, the current density (Ip) becomes almost uniform near and on both sides of the filament, and the current density (Ib) does not contribute to light emission.
ack) hardly flows. That is, it can be seen that the light emission luminance of each part of the anode electrode becomes uniform, and there is almost no reactive current.

In the case of FIG. 9B, the control voltage (Ebac
k) is 0 V, the current density (Iba
ck), but the current density (Ip) contributing to light emission hardly occurs in the intermediate portion between the filaments F1 and F2. That is, the phosphor of the anode electrode corresponding to the intermediate portion does not emit light. When the control voltage (Eback) is 3 V, the current density (Ip) contributing to light emission becomes almost uniform at all portions of the anode electrode, but the current density (Iback) serving as a reactive current is reduced by the filaments F1 and F2.
It becomes large near.

From this result, it can be seen that the potential gradient of the control voltage is effective in uniformly emitting electrons emitted from the filament to each portion of the anode electrode and making the current density in each portion uniform. Potential gradient voltage 0V, 2V, 4
V, 3 V, 6 V, etc. may be supplied using a power supply that generates these voltages, or may be supplied by a voltage dividing circuit using a resistor or the like. In the case of using a resistor, the resistance value of each electrode may be different depending on the shape and material of the back electrode.

Although the simulation was performed for the distance between the filaments F1 and F2 and the anode electrode A1 of 0.7 mm, the distance may be in the range of 0.1 mm to several mm. Here, if the cutoff potential applied to the control electrode is increased, the distance between the filament and the anode electrode can be increased. However, considering the withstand voltage and cost of the driving IC, the distance is set to 0. It is more preferably about 0.5 mm to 1.5 mm.

[0044]

As described above, the fluorescent display tube of the present invention comprises a substrate on which an anode electrode, an insulating layer, a grid and a phosphor layer are formed.
Since the concave portion is formed and the phosphor layer is formed in the concave portion, by adjusting the depth of the concave portion, the height of the phosphor layer can be arbitrarily easily adjusted such that the height of the phosphor layer is substantially the same as the height of the grid. Can be set. In the fluorescent display tube of the present invention, by providing the concave portion of the substrate with a taper, the concave portion of the grid can also be provided with a taper, so that the cut-off characteristic of the grid is improved, and the insulating layer exposed in the concave portion is formed. Since the size is reduced, charge-up of the insulating layer can be reduced.

In the fluorescent display tube of the present invention, since the back electrode supplements the function of the grid even when the grid is disposed at a lower position than the phosphor by providing the back electrode, the filament emits light from the filament to the anode electrode. The electronic control performed can be reliably performed without any trouble. In the fluorescent display tube of the present invention, the anode electrode, the insulating layer, and the grid are formed of a thin film, and the position of the grid is set to be substantially the same height as the phosphor or lower than the phosphor, so that the charge-up of the insulating layer is reduced. And the phenomenon of electron scuffing can be reduced. Further, since the insulating layer of the present invention is a thin film, the thickness of the insulating layer is 1 times that of a conventional thick film.
Since the value is 1/0 or less, the charge-up of the insulating layer can be improved from this point as well.

The fluorescent display tube of the present invention comprises an anode electrode,
By forming the insulating layer and the grid with thin films, it has become possible to manufacture a high-definition fluorescent display tube. By setting the height of the grid and the phosphor as described above, it is possible to suppress the charge-up of the insulating layer of the conventional fluorescent display tube even in the case of a high definition structure. In the fluorescent display tube of the present invention, the mask vapor deposition can be performed by forming the notch in the concave portion of the grid. As a result, the opening of the concave portion can be formed at the same time as the formation of the grid, so that the manufacturing process is simplified and grids having a small width can be arranged at a narrow pitch.

The fluorescent display tube of the present invention has a back electrode, which is disposed on the side opposite to the anode electrode with the filament interposed therebetween. The release stop can be easily controlled, and by providing a potential gradient to the control voltage,
Electrons emitted from the filament to each part of the anode electrode can be uniformly diffused, and a planar electron source having a substantially uniform electron density can be realized.

The fluorescent display tube of the present invention switches between a filament for emitting electrons and a filament for stopping emission by a filament voltage applied to the filament.
Alternatively, the emission of electrons emitted from the filament can be performed and stopped more easily and reliably, and the uniformity of the emitted electrons can be achieved by adding the action of the back electrode. .

[Brief description of the drawings]

FIG. 1 is a plan view of a first substrate of a fluorescent display tube according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a first substrate of the fluorescent display tube according to the embodiment of the present invention.

FIG. 3 shows an enlarged view of a part of FIG.

FIG. 4 shows a manufacturing process of a first substrate of the fluorescent display tube according to the embodiment of the present invention.

FIG. 5 shows a sectional view of a fluorescent display tube according to an embodiment of the present invention and a method of applying a control voltage.

FIG. 6 shows a sectional view of a fluorescent display tube according to an embodiment of the present invention and a method for applying a filament selection voltage.

FIG. 7 shows an embodiment of a filament switching circuit of the fluorescent display tube of the present invention.

FIG. 8 shows a structure of a model fluorescent display tube used for an electric field analysis simulation of the fluorescent display tube of the present invention.

FIG. 9 shows a result of an electric field analysis simulation of the fluorescent display tube of the present invention.

FIG. 10 shows a structure of a conventional fluorescent display tube.

[Explanation of symbols]

 A, A1 to An Anode electrode B1 to B9 Back electrode Bs Bottom part C Cutout part D Insulating layer F1, F2 Filament G, G1 to G7 Grid H, H11 to H7n Phosphor Ka, Kd, Kg, Ks Depression Od, Og Opening S glass substrate S1 first glass substrate S2 second glass substrate Ta, Td, Tg, Ts Taper

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Katsutoshi Mukago 629 Futaba Electronics Co., Ltd., Oshiba, Mobara City, Chiba Prefecture (72) Inventor Hiroaki Kawasaki 629 Futaba Electronics Industry Co., Ltd., Oshiba, Mobara City, Chiba Prefecture Reference) 5C036 EF01 EF06 EF08 EG02 EG36 EH04 EH06 5C080 AA08 BB05 DD05 HH18 JJ02 JJ05 JJ06

Claims (12)

[Claims] A striped anode electrode and a striped grid are formed in a matrix through an insulating layer, and an opening is formed in the insulating layer and the grid where the anode electrode and the grid intersect; In a fluorescent display tube in which a cathode is arranged between a first substrate coated with a phosphor on an anode electrode in an opening and a second substrate facing the first substrate, the first substrate includes at least the phosphor. A fluorescent display tube, wherein a recess for accommodating the fluorescent display tube is formed. 2. The fluorescent display tube according to claim 1, wherein
The concave portion of the first substrate has a tapered inner surface. 3. The fluorescent display tube according to claim 1, wherein
A fluorescent display tube, wherein a concave portion laminated along the inner surface of the concave portion of the first substrate is formed in the insulating layer and the grid. 4. The fluorescent display tube according to claim 3, wherein
A fluorescent display tube characterized in that a concave portion of the grid has a tapered inner surface. 5. The fluorescent display tube according to claim 1, wherein
A fluorescent display tube, wherein the surface of the phosphor is arranged on the cathode side with respect to the surface of the grid contacting the insulating layer. 6. The fluorescent display tube according to claim 1, wherein
A fluorescent display tube, wherein the surface of the first substrate opposite to the surface on which the recess is formed is a rough surface. 7. The fluorescent display tube according to claim 1, wherein
A fluorescent display tube characterized in that a stripe-shaped back electrode is formed on a second substrate. 8. The fluorescent display tube according to claim 7, wherein
A fluorescent display tube provided with means for setting a potential gradient to a filament selection voltage applied to a back electrode. 9. The fluorescent display tube according to claim 7, wherein
A method of driving a fluorescent display tube, characterized in that a filament selection voltage and a filament non-selection voltage are applied in a time division manner to each filament control group of a back electrode to select a filament from which electrons are emitted. 10. A fluorescent display tube according to claim 7, wherein a filament selection voltage and a filament non-selection voltage are applied to the filament in a time division manner to select a filament that emits electrons. Drive method. 11. The method according to claim 9, wherein a potential gradient is provided in the filament selection voltage. 12. The fluorescent display device according to claim 7, wherein a grid selection voltage is applied to the grid in a time-division manner, and a data signal is input to the anode electrode to select a phosphor to emit light. How to drive the display tube.