JPH0624094B2 - Fluorescent display tube control electrode - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrode material of a fluorescent display tube, and particularly to a material for a control electrode thereof.

[Conventional Technology] A conventional technology will be described by taking a fluorescent display tube having a general structure as an example.

In general, a fluorescent display tube has a box-shaped envelope whose inside is held in a high vacuum atmosphere. Inside the envelope, there are a filament-shaped cathode that emits electrons, a mesh-shaped control electrode that accelerates and controls the electrons, and an anode that is coated with a phosphor layer that emits light by electron bombardment. It is stored and arranged. And a typical mounting method of the control electrode
As a structure, a center attachment method and a spacer frame method are known. The centering method is to form a rising piece portion and an adhesive portion continuous to this on both ends of the mesh-shaped control electrode, and to form a wiring terminal on the inner surface of the substrate forming a part of the envelope by a conductive adhesive. The adhesive portion is adhered and fixed, and the mesh-shaped control electrode is arranged at a predetermined height above the inner surface of the substrate. As shown in FIG. 5, the spacer frame method uses an electrode structure 3 in which various electrodes are continuously provided inside an electrode frame 2 which is slightly larger than the substrate 1. That is, inside the electrode frame 2, the cathode support 4 and the cathode lead 4a, the mesh fixing frame 5 and the control electrode lead 5a continuous thereto, and the anode lead whose end is connected to the connection terminal on the substrate 1 6 is integrally formed. Then, as shown in FIG. 4, a mesh frame 10 having a mesh portion 9 composed of a mesh 7 and a mesh frame 8 integrally formed of the same metal is overlaid on the electrode frame 2, and the mesh portion 9 is formed into the mesh. Weld to the fixed frame 5. Then, after positioning the electrode structure 3 thus constructed on the substrate 1, the container portion 11 assembled in a box lid shape is sealed on the substrate 1 to form an envelope, and the sealing portion is formed. The leads 4a, 5a, 6 led out to the outside of the envelope by airtightly were separated from the electrode frame 2.

By the way, in the spacer frame type fluorescent display tube, since the lead portions 4a, 5a, 6 penetrate the sealing portion of the envelope, generally, the lead portions 4a, 5a,
6 and the electrode frame 2 and the like formed integrally therewith are well compatible with the sealing glass, and the coefficient of thermal expansion is close to that of the sealing glass, so that there is little leakage at the sealing portion 426.
Alloy (comprising at least Ni, Cr, Fe as main components, Ni 40 to 46%, Cr 3 to 8%, balance Fe, or a small amount of element added to this basic component for the purpose of improving specific characteristics) Since these groups of alloys are commonly referred to as 426 alloys, such alloys are again collectively referred to as 426 alloys). Then, for the mesh portion 9 welded to the mesh fixing frame 5 made of 426 alloy, a metal material cheaper than the 426 alloy, for example, SUS304, SUS430, etc., was used. These metals had a larger coefficient of thermal expansion than the 426 alloy. The 426 alloy and the coefficients of thermal expansion of these alloys are as follows.

[Problems to be Solved by the Invention] In the envelope of the fluorescent display tube, a part of the electrons emitted from the cathode collide with the mesh portion 9 of the control electrode to generate a reactive current. At this time, all the kinetic energy possessed by the electrons becomes heat, so that the temperature of the mesh portion 9 rises and the temperature during lighting reaches 200 ° C to 250 ° C. Mesh part 9
Although heat is transmitted to the mesh fixing frame 5 where is fixed,
Since the control electrode lead 5a is integrally provided on the mesh fixing frame 5 and is led out to the outside of the envelope, the temperature does not rise so much, and the temperature is about 90 ° C. at the highest. And, as described above, all the conventional metal materials forming the mesh portion 9 have a larger thermal expansion coefficient than the 426 alloy forming the mesh fixing frame 5 and the like. Therefore, the mesh fixing frame 5
The mesh portion 9 fixed at room temperature has a larger amount of thermal expansion than the electrode frame 2 at the time of lighting, and the mesh 7 is deformed into a shape in which the central portion is projected toward the cathode K side or the anode A side. I will end up. When the amount of deformation increases, the cathode K
Alternatively, there is a problem that the control electrode G may come into contact with the anode A. Even if the mesh 7 does not come into contact, the density of the anode current changes due to the deformation of the mesh 7, which may cause uneven brightness or flicker in the display.

In order to solve the above-mentioned problems, the following measures (1) to (4) have been conventionally taken, but as described in each section, each of these methods also has its own problems. However, the problem that the control electrode G is deformed is not completely solved.

(1) The display pattern is divided, and the size of one control electrode is reduced to reduce the amount of thermal deformation of each mesh so that each control electrode does not contact another electrode.

However, some display patterns cannot be divided, and if the display screen is composed of a large number of control electrodes having small dimensions, the display density becomes low.

(2) As shown in Japanese Utility Model Laid-Open No. 60-96763, a part of the mesh should be provided with a supporting claw protruding toward the substrate, and the mesh should be deformed into the shape protruding toward the substrate and contact the anode. Prevent.

However, this method has a problem in that the number of steps for processing the supporting claws is increased, so that the manufacturing cost is increased, and the supporting claws are obstructed to make it difficult to see.

(3) Fix the mesh grid of the internal mounting method to the electrode frame side in the state of being heated to a temperature higher than that at lighting and expanded,
A technique for applying a tensile stress to the mesh portion at room temperature is disclosed in Japanese Utility Model Publication No. 58-40523.

However, it is difficult to work at a temperature higher than that during lighting, that is, generally at a temperature of 250 ° C. or higher, and this method may deform the electrode frame during non-lighting.

(4) As shown in Japanese Utility Model Publication No. 58-41635, deformation is prevented by making a cut in a portion of the mesh portion that does not obstruct the display to reduce the area of the control electrode.

However, in this method, the deformation may be up or down on both sides of the cut, resulting in uneven brightness at the cut. Further, according to this method, there is a problem that the manufacturing cost increases due to an increase in the number of processing steps.

[Object of the Invention] The present invention determines the shape of the thermal expansion curve from the envelope glass or 42.
It is an object of the present invention to provide a control electrode material capable of significantly suppressing the deformation of the control electrode of the fluorescent display tube due to the thermal expansion and contraction of the control electrode of the 6-alloy frame, by judiciously matching it. I am trying.

[Means for Solving the Problems] The material for a fluorescent display tube control electrode of the present invention is Fe—Ni—C for a centering type or spacer frame type fluorescent display tube.
In the r-based material, C is 0.05% or less and Si is 0.
05-0.50%, Mn 0.05-0.50%, Ni over 37% 4
0.0% or less, Cr 1.0-7.5%, the balance Fe, and to keep the difference between the amount of nickel and the amount of chromium within an appropriate range, 3
The composition is characterized in that the composition satisfies the condition of 2.5% ≤ Ni-Cr ≤ 36%.

Furthermore, this composition contains 0.05-0.5% Al and 0.05% by weight.
Either or both of 0.5 to 0.50% Ti may be contained.

[Operation] The coefficient of thermal expansion of the material for controlling a fluorescent display tube of the present invention is lower than that of a sealing alloy such as 426 alloy at room temperature (30 ° C.) to about 250 ° C., and about 250 ° C. In the higher temperature region, the thermal expansion coefficient is close to that of the sealing alloy and the envelope glass.

[Examples] The reasons for limiting the components of the material for a fluorescent display tube control electrode according to the present invention are as follows.

That is, C needs to be contained to some extent as a deoxidizing agent when the alloy is melted, but if it exceeds 0.05%, it causes bubbles in the sealed glass during glass sealing, so the content is limited to 0.05% or less. Si is used as a deoxidizer when melting the alloy, but 0.05
If it is less than 0.1%, there is no effect, and if it exceeds 0.05%, the workability of the alloy is impaired, so it was limited to 0.05 to 0.50%. M
The reason for n is the same as that for Si. Ni and Cr are the basic compositions of the present alloy, and both are alloy elements that greatly affect the thermal expansion characteristics, but their thermal expansion coefficients are room temperature (30
C) to 250 ° C., smaller than glass, preferably smaller than 426 alloy, and higher temperature, 250 ° C. to 400 ° C., larger than glass, preferably larger than 426 alloy. % Or less, Cr
The condition of 32.5% ≦ amount of Ni−amount of Cr ≦ 36% was satisfied at 1.0 to 7.5%. That is, it is limited to the range within the rhombus shown in FIG. Particularly, the Ni content is 30 to 25
Related to the coefficient of thermal expansion on the low temperature side of 0 ° C., the higher the Ni content, the greater the coefficient of thermal expansion and the greater the elongation of the mesh. In the present invention, in a temperature range of 30 to 250 ° C. during lighting, a member for fixing a mesh, that is, a glass substrate is used for the in-core method and an elongation rate of the mesh is smaller than that of the spacer frame for the spacer frame method, and the mesh is transformed It is intended to reduce the lifting amount (displacement amount) of the mesh by applying an appropriate tension that does not cause peeling or peeling.

Therefore, in the case of the internal attachment method, the elongation rate may be slightly smaller than that of glass, and in the spacer frame method, the elongation rate may be slightly smaller than that of the 426 alloy which is the spacer frame member. If the elongation of the mesh is too small, the mesh will be over-tensioned, which may cause peeling at the bonded portion of the mesh in the in-core method. In the spacer frame method, since spot welding is partially performed, peeling does not occur, but the mesh may deform.

Therefore, the content of Ni satisfying the above conditions is 33.5.
-40%, but from the distribution of alloy examples within the trapezoid in Fig. 37
Divided into groups of less than% and groups of more than 37%.
The group containing Ni of 37% or less is alloy Nos. 1, 2, 6 and 7, and in FIG. 1, alloy examples of No. 1 and No. 2 are described. Alloys No. 3 to No. 5 for groups of 37% or more
And No. 8 to No. 10, of which N in FIG.
o.4 and No. 5 alloy examples are described.

As can be seen from FIG. 1, the group of Ni 37% or more has a value smaller than or closer to the elongation of the plate glass or the 426 alloy. That is, it is a better condition that tension is generated in the mesh but peeling or deformation does not occur completely.

Therefore, the range of Ni content of 37 to 40% (not including 37%) is a desirable range as the mesh material used for the fluorescent display tube. Therefore, this is adopted in the present invention.
The content of Cr is 1.0 to 7.5%, and the amount of Ni is C
It is a necessary condition to satisfy the condition of the value obtained by subtracting the amount of r, that is, 32.5% ≦ Ni—Cr ≦ 36%. And shown in Table 2
Alloys Nos. 11 to 13 are alloys having compositions that do not meet the above conditions, and are also shown in FIG. 2 for comparison with the present invention. With such is out of the range of rhombic, the average thermal expansion coefficient alpha _30-250 not within the range of ^{5.0 × 10 -6 /℃~7.3 × 10 -6} / ℃. Average thermal expansion coefficient α _30-250 is 7.3 ×
If it is higher than 10 ⁻⁶ / ° C., the mesh will be thermally deformed during use as described above, and peeling may occur at the bonded portion of the mesh depending on the in-core method. Α _30-250 is 5.0
If it is less than × 10 ^-6 / ° C, excessive tension will be applied to the mesh, and this force will be so large that it cannot be ignored in practice. Furthermore, Al and T
If necessary, i is contained to improve the adhesion of the oxide film to the base alloy, but if it is less than 0.05% it has no effect, and if it exceeds 0.50% the workability of the alloy is impaired. It was limited to 0.05 to 0.50%. Table 1 shows the conventional alloys of 426 alloy and 18Cr stainless steel (shown as No. 426 and No. 18 respectively).
The chemical compositions and average coefficients of thermal expansion of Examples Nos. 3 to 5 and Nos. 8 to 10 of the present invention and Comparative Examples Nos. 1 and 2 and Nos. 6 and 7 are shown. FIG. 2 plots the content rates of Ni and Cr in each of the examples and comparative examples, and further shows the ranges of the content rates of Ni and Cr in the present invention including these points. That is, an alloy having such a chemical composition range generally has an average thermal expansion coefficient lower than that of the 426 alloy at a temperature range of 30 ° C. to 250 ° C. which is considered to be a temperature range when the fluorescent display is lit, and its value is about 5.0. × 10 ^-6 / ℃ ~
It is within the range of 7.3 × 10 ^-6 / ° C. In addition, in FIG.
Correlation between elongation and temperature is shown for some Example Nos. 4, 5 and Comparative Examples 1, 2, 426 alloy and sheet glass. That is, as can be seen from FIG. 1, the elongation rate of alloy 426 is higher than that of alloys Nos. 1, 2, 4, and 5 up to about 250 ° C., and the elongation rates of both are higher in a temperature range higher than this. Are almost equal. However, Alloys Nos. 1 and 2 are somewhat inappropriate as described above and are not the present invention.

The alloys of Alloy Examples Nos. 1 to 10 were melted in a vacuum high frequency induction melting furnace with the composition shown in Table 1 and finished into plate materials by hot rolling and cold rolling. Next, a spacer frame type fluorescent display tube having a portion constituted by using these alloys will be described. The shape and structure thereof are almost the same as those of the fluorescent display tube illustrated and described in the section "Prior Art". .

First, an Al thin film is deposited on a glass substrate by a sputtering method, and an anode conductor and a wiring conductor having a desired pattern are formed by a photolithography method. A thick insulating layer is deposited on the glass substrate by a screen printing method so as to surround the anode conductor and baked, and a phosphor layer is deposited on the anode conductor by an electrodeposition method or a screen printing method and baked.

Next, an electrode structure having control electrodes is formed. The electrode frame is formed by processing 426 alloy, which has a thermal expansion coefficient substantially equal to that of glass, by pressing or etching. Then, the electrode frame is heat-treated in advance in a hydrogen furnace, and a chromium oxide layer is formed on the surface thereof to improve the adhesion with the sealing glass.

Then, the plate material made of the metal material of Alloy Nos. 1 to 10 is subjected to etching processing to form the mesh frame 10 having the mesh portion 9 composed of the mesh 7 and the mesh frame 8. The mesh frame 10 is overlaid on the electrode frame 2, the mesh frame 8 is welded to the mesh fixing frame 5 at several points, and the mesh portion 7 is separated from the mesh frame 10.
Then, the cathode K in the form of a filament is welded and stretched on the cathode support 4 to form the electrode assembly 3.

Next, the side plate and the top plate made of glass are assembled into a box shape with low melting point frit glass to form the container part 11.
Further, the electrode structure 3 is arranged on the glass substrate 1.
Then, the container portion 11 is covered from above, and the lead portion 5a of the electrode frame 2 is sandwiched between the container portion 11 and the glass substrate 1 to be sealed by frit glass which is heated and melted. The temperature at the time of sealing is generally 450 ° C to 550 ° C. As shown in FIG. 1 and Table 1, alloy No.
The elongation percentages of the metallic materials 1, 2, 4, 5 are almost the same as those of the 426 alloy. Therefore, in the sealing step in assembling the fluorescent display tube, the electrode frame 2 made of the 426 alloy and the mesh portion 9 made of the metal material of each alloy example have substantially the same thermal deformation amount, so that either one is plastically deformed. There is nothing that will cause it.

Then, the gas inside is discharged through an exhaust hole provided in a key part of the envelope, and when the inside is in a high vacuum state, the exhaust hole is sealed by an exhaust lid or a tip tube. Finally, lighting is performed to activate the cathode and further aging is performed.

Next, a case where the fluorescent display tube manufactured as described above is driven to emit light will be described. As shown in FIG. 1 and Table 1, in the temperature range below about 250 ° C., which is the maximum mesh temperature during operation of a general fluorescent display tube, the metal material of the example has a coefficient of thermal expansion of 426 alloy. Is smaller than. Therefore, when the fluorescent display tube of the present embodiment is turned on, the deformation amount is smaller in the mesh portion than in the electrode frame. More specifically, the mesh of the fluorescent display tube in each alloy example has a smaller lifting amount (deformation amount) at the time of lighting than the conventional product, and also has a lifting amount with the passage of time after energization. It decreases, and finally the lift amount becomes 0 or close to 0. That is, as shown in FIG. 3, a mesh part made of a metal material having a thermal expansion coefficient larger than that of the 426 alloy or an equivalent metal material is used as the 426 alloy.
According to the curve of the conventional example F426 fixed to the alloy electrode frame, the mesh portion is thermally deformed and lifted immediately after energization, and the deformation amount hardly changes with time. However, for example, according to the curves shown in the examples F1 and F5 of the fluorescent display tube in which the mesh portion made of the alloy examples No. 1 and No. 5 is fixed to the electrode frame of 426 alloy, the mesh lifting amount is about The maximum value is reached in 15 seconds, but this maximum value is smaller than the maximum value of the curve shown in the conventional example F426, and the mesh lifting amount decreases with the lapse of time and returns to the original value after about 1 minute. .

Next, the reason why the mesh using the alloy material of the embodiment changes with time and returns to its original state will be described. First, the mesh part having a small heat capacity quickly rises in temperature by the start of energization due to the difference in heat conduction between the mesh and the electrode frame.
The maximum thermal deformation occurs in seconds. At this time, the electrode frame having a large heat capacity has a low temperature and is not deformed. After 15 seconds, heat is also conducted to the 426 alloy electrode frame.
Although the temperature of the electrode frame at this time is not as high as that of the mesh portion, the coefficient of thermal expansion is larger than that of the mesh portion, so that the elongation rate is large. Then, the thermal expansion of the mesh portion having a small thermal expansion coefficient becomes relatively smaller than the thermal expansion of the electrode frame, and the mesh is pulled by the electrode frame to reduce the displacement amount (lifting amount). When the displacement amount decreases, the distance between the cathode and the control electrode increases, so that the control electrode current decreases and heat generation decreases. As a result, the temperature of the mesh is lowered, and the displacement amount of the mesh is further reduced. In this way, after about 1 minute of lighting, as shown by the solid line in FIG. 3, the lifting amount of the mesh is reduced to 0 or a value close to 0. As can be seen from the figure, according to the mesh portion made of the alloy material of the embodiment, unlike the conventional example F426 curve of FIG. 3, even when it is applied to a fluorescent display tube with considerably large power consumption, The lifting amount of the mesh can be made close to zero.

As described above, the control electrode material of this example has a coefficient of thermal expansion of 42 up to around 250 ° C. which is the lighting temperature of the fluorescent display tube.
Since it is smaller than 6 alloy, if the mesh part formed of this material is welded and fixed to the electrode frame of 426 alloy,
The deformation of the mesh during lighting can be minimized. Then, for example, the amount of deformation of the mesh can be stabilized to 0 in about one minute after energization, and the flicker of brightness can be eliminated.

In the embodiments described above, the lead frame type fluorescent display tube is taken as an example, and the example in which the mesh portion is made of the alloy of the present invention is shown, but the application range of the alloy material of the present invention is limited to the above examples. It is not something that will be done.

EFFECTS OF THE INVENTION According to the material for a fluorescent display tube control electrode of the present invention, the coefficient of thermal expansion is smaller than that of 426 alloy or glass in the temperature range lower than the lighting temperature of the display tube, and the temperature range is higher than the temperature range. Has a thermal expansion coefficient close to that of 426 alloy or glass. Therefore, according to the present invention, it is possible to suppress the deformation of the parts inside the tube when the display tube is lit, and it is possible to reduce the adverse effect on the performance of the display tube.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the elongation rate and temperature in the example of the present invention, the conventional example, and sheet glass, and FIG. 2 is a view showing the relationship between the Ni and Cr contents in each alloy example of the present invention.
FIG. 3 is a graph showing the relationship between the amount of mesh lifting and the elapsed time after energization in a fluorescent display tube having a mesh made of the material of each alloy example and a conventional fluorescent display tube, and FIG. 4 is a spacer frame type fluorescent display. FIG. 5 is a perspective view showing an electrode frame and a mesh frame in the display tube, and FIG. 5 is an exploded perspective view of a spacer frame type fluorescent display tube. 1 ... Substrate, 2 ... Electrode frame, 5 ... Mesh fixed frame, 7 ... Mesh, 8 ... Mesh frame, 9 ... Mesh part, 10 ... Mesh frame.

Claims (2)

[Claims] 1. A Fe-Ni-Cr-based material for a center-display type or spacer frame type fluorescent display tube, wherein the weight% is
C is 0.05% or less, Si is 0.05 to 0.50%, Mn is 0.05 to
0.50%, Ni over 37% and 40.0% or less, Cr 1.0-7.5
%, The balance being Fe, and having a composition satisfying 32.5% ≦ Ni—Cr ≦ 36%, a material for controlling a fluorescent display tube. 2. An Fe-Ni-Cr-based material for a fluorescent display tube having a centering method or a spacer frame method, wherein the weight% is
C is 0.05% or less, Si is 0.05 to 0.50%, Mn is 0.05 to
0.50%, Ni over 37% and 40.0% or less, Cr 1.0-7.5
%, And 0.05 to 0.50% Al and / or 0.05 to 0.50% Ti, and the balance is Fe, and the composition is 32.5% ≦ Ni—Cr ≦ 36%. Fluorescent display tube control electrode material.