JPH05144392A - Fluorescent display tube - Google Patents

Abstract

PURPOSE:To prevent a control electrode from bending largely due to heat when it is used, by enabling the control electrode to be fixed in a tensile force applied condition in a fluorescent display tube having such a structure as to fix the control electrode onto a glass substrate by means of a glass adhesive. CONSTITUTION:A control electrode made of an alloy composed of Ni 34%, Cr 3% and the residual part Fe has an elongation percentage larger than that of a glass substrate around 350 deg.C being a fixing temperature of a glass adhesive. Thereby, this control electrode is fixed in an elongated condition, so that a tensile force is applied thereto. The elongation percentage of this electrode is smaller than that of the glass substrate around 150 deg.C being a control electrode temperature when a fluorescent display tube is lighted. Thereby, even if the control electrode temperature rises when the fluorescent display tube is lighted, neither the tensile force becomes 0, nor sagging is caused in the control electrode.

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 having a structure in which a control electrode is directly fixed on a glass substrate of an envelope by using a glass adhesive, and particularly, the control electrode is thermally deformed during operation. This is something that was not done.

[0002]

2. Description of the Related Art Generally, a fluorescent display tube has an envelope in which an insulating material such as a glass plate is assembled in a box shape with a glass adhesive, and the inside thereof is evacuated to a high vacuum state. An anode having a phosphor is provided on the inner surface of a glass substrate which is a part of the envelope, and a control electrode and a linear cathode are further provided above the anode.

The control electrode may be, for example, a mesh type or a wire type. These control electrodes are generally fixed to the glass substrate of the envelope by using a glass adhesive material. For example, the mesh-shaped control electrode may be directly adhered to the inner surface of the glass substrate by using a glass adhesive, and in the case of the wire-shaped control electrode, both ends of the tensioned control electrode may be enclosed in an envelope. It may be fixed by a glass adhesive at the sealing portion of the glass substrate.

The control electrode described above may be, for example, the actual development 54
-96149, SUS430 (α≈110) having a larger coefficient of thermal expansion than a glass substrate.
A metal material such as × 10 ⁻⁷ / ° C.) may be used. As shown as a conventional example in FIG. 1, SUS430
Shows a considerably larger elongation than the glass substrate at around 350 ° C., which is the fixing temperature of the glass adhesive. Therefore, in assembling the fluorescent display tube, the control electrode expands more than the glass substrate at the fixing temperature, and tension is applied to the control electrode after the fixing.

[0005]

However, the above-mentioned metallic material has a larger elongation than that of the glass substrate not only in the vicinity of the fixing temperature but also in all temperature ranges above room temperature. For this reason, when the temperature of the control electrode rises to some extent during the operation of the fluorescent display tube, the control electrode sometimes sags due to the difference in elongation.

For example, the grid span of the control electrode is 30.
mm, the fixing temperature is 320 ° C., the expansion coefficient of the glass substrate is 8
Considering 5 × 10 ⁻⁷ / ° C. and room temperature of 30 ° C., the length by which the control electrode is expanded to the glass substrate after being fixed is as follows. 30 mm × (320 ° C.−30 ° C.) × (110−85) × 10 ⁻⁷ / ° C. = 0.02 175 mm That is, the control electrode is subjected to a tensile tension of such a length at room temperature. Here, when the temperature T when the temperature of the control electrode rises and extends 0.02175 mm during use is calculated, if the temperature of the glass substrate is 30 ° C., then 30 mm × (T−30 ° C.) × 110 × 10 ⁻⁷ / ° C. = 0.02175 mm ∴T = 95.9 ° C. That is, if it becomes 95.9 ° C. or higher, the control electrode will bend. In some fluorescent display tubes mounted on a vehicle, the temperature of the control electrode during use becomes about 150 ° C., and the control electrode may be thermally deformed as described above with conventional materials.

According to the present invention, in a fluorescent display tube having a structure in which a control electrode is fixed to a glass substrate with a glass adhesive, the control electrode can be fixed while tension is applied, and the control electrode is largely bent due to heat during use. The purpose is not to.

[0008]

The fluorescent display tube of the present invention comprises:
An envelope having a glass substrate and being kept in a high vacuum state, an anode having a phosphor layer formed on an inner surface of the glass substrate, and an envelope provided above the anode in the envelope. In a fluorescent display tube having a control electrode fixed to the glass substrate with a glass adhesive and a linear cathode provided above the control electrode in the envelope, heat at the fixing temperature of the glass adhesive is used. The coefficient of expansion is greater than the coefficient of thermal expansion of the glass substrate, and the coefficient of thermal expansion at the temperature of the control electrode during operation of the fluorescent display tube is a metal material smaller than the coefficient of thermal expansion of the glass substrate, the control electrode, It is characterized by being configured.

[0009]

When the control electrode is fixed with the glass adhesive, the control electrode expands more than the glass substrate, so that tension is generated in the control electrode after the fixing. At the operating temperature of the fluorescent display tube, the elongation of the control electrode is smaller than that of the glass substrate, and therefore the thermal deformation of the control electrode is small.

[0010]

EXAMPLES Table 1 shown below shows Examples 1 and 2 of the present invention and the expansion coefficient of the glass substrate (soda glass). Further, FIG. 1 shows a comparison of the elongation percentages of the glass substrate with the conventional example and Examples 1 and 2 described above.

[0011]

[Table 1]

The metal material of Example 1 is Ni36%, Cr5
%, Balance Fe, and the metal material of Example 2 is Ni
It is an alloy of 34%, Cr 3% and balance Fe. Both
The coefficient of thermal expansion is higher than that of the glass substrate at around 350 ° C., which is the fixing temperature of the glass adhesive, and is smaller than that of the glass substrate up to about 150 ° C., which is the temperature of the control electrode when the fluorescent display tube is lit. ing.

In Example 1 having the above-mentioned thermal expansion coefficient, what kind of tension is applied to the control electrode fixed to the glass substrate with the glass adhesive, and how the tension is applied when the fluorescent display tube is turned on. Whether to change to will be described based on the calculation in the above-described conventional example.

When the grid span of the control electrode is 30 mm, the fixing temperature is 320 ° C., and the room temperature is 30 ° C., the elongation of the control electrode fixed to the glass substrate is as follows. 30mm × (320 ° C.−30 ° C.) × (105−85) × 10 ⁻⁷ / ° C. = 0.01 74 mm That is, the control electrode is fixed in a state of being stretched by 0.0174 mm and is under tension. ..

Next, at the time of lighting, the temperature of the control electrode rises and the control electrode expands due to heat.
The temperature T (° C.) at which the tension reaches 4 mm and the tension becomes 0 is calculated. 30 mm × (T−30 ° C.) × 50 × 10 ⁻⁷ / ° C. = 0.0174 mm ∴T = 146 ° C. That is, according to the first embodiment, the control electrode can be fixed in a state where sufficient tension is applied, Furthermore, the tension of the control electrode can be maintained even when heat is generated when the fluorescent display tube is turned on.

In addition, when the case of the second embodiment is calculated under the same conditions, as shown in Table 1, the control electrode at the time of adhesion is 0.
The temperature at which the tension is applied at the elongation of 0261 mm, and the tension of the control electrode becomes 0 when the elongation is cancelled, is 145 ° C.

FIGS. 2A and 2B show a so-called centering type control electrode 1 using a metal material as in the first and second embodiments.
Is shown. When the control electrode 1 is attached, the paste for paste is printed on the glass substrate 2, the claws 3 of the control electrode 1 are inserted therein, and baking is performed at 450 ° C to 500 ° C. The frit glass 4, which is the adhesive glass in the paste for inside coating, melts and flows. Then, the cooling process is started, and the temperature is lowered to about 320 ° C. where the frit glass 4 is fixed. During this time, since the frit glass 4 has fluidity, the control electrode 1 can freely expand. As described above, in this temperature range, the elongation of the control electrode 1 is larger than that of the glass substrate 2, so that at the fixing point of the frit glass 4, the control electrode 1 is fixed in the expanded state. Then, below the fixing temperature, tension is applied to the control electrode 1. Then, as described above, the tension of the control electrode 1 can be maintained with respect to the heat generated when the fluorescent display tube is used.

FIG. 3 shows a fluorescent display tube having a wire-shaped control electrode 5 made of a metal material as in the first and second embodiments. When attaching the wire-shaped control electrode 5 as described above, the control electrode 5 is pulled by using a jig (not shown) so that the thermal expansion of the control electrode 5 at the time of heat sealing is released to the outside of the envelope 6. .. Then, the wire-shaped control electrode 5 is fixed in a stretched state by the glass adhesive material 7 at the sealed portion of the envelope 6. Then, tension is generated in the control electrode 5 at a temperature equal to or lower than the fixing point of the glass adhesive material 7.

[0019]

As described above, according to the present invention,
The coefficient of thermal expansion near the fixing temperature is larger than that of the glass substrate,
Since the control electrode is made of a metal material whose coefficient of thermal expansion at the time of lighting is smaller than that of the glass substrate, tension is applied to the control electrode after sealing to prevent slack, and the coefficient of thermal expansion of the control electrode during operation is reduced. Since it is small, there is an effect that thermal deformation is small.

Therefore, even if a large amount of electric power is applied to the control electrode to generate heat, it does not deform up to a predetermined temperature.
It has become possible to increase the electric power applied to the control electrode by, for example, about twice. By doing so, the brightness of the fluorescent display tube can be improved by about 1.5 times, and a practically important effect can be expected as a vehicle-mounted graphic fluorescent display tube that requires high brightness.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between temperature and elongation for each of Examples 1 and 2, a conventional example, and a glass substrate.

FIG. 2 is a view showing a control electrode of a built-in type.

FIG. 3 is a cross-sectional view of a fluorescent display tube having a wire-shaped control electrode.

[Explanation of symbols]

 1,5 control electrode 2 glass substrate 4 frit glass as glass adhesive 6 envelope 7 glass adhesive

Claims (2)

[Claims] 1. An envelope which has a glass substrate and is held in a high vacuum state inside, an anode having a phosphor layer formed on the inner surface of the glass substrate, and an anode of the anode in the envelope. In a fluorescent display tube having a control electrode provided above and fixed to the glass substrate with a glass adhesive, and a linear cathode provided above the control electrode in the envelope, the glass adhesive A metal material whose coefficient of thermal expansion at a fixing temperature is larger than that of the glass substrate, and whose coefficient of thermal expansion at the temperature of the control electrode during operation of the fluorescent display tube is smaller than that of the glass substrate. A fluorescent display tube comprising the control electrode. 2. The glass substrate is made of soda glass, and has a coefficient of thermal expansion of 85 to 95 × 10 within a range of a temperature of the control electrode and a fixing temperature of the glass adhesive during operation of the fluorescent display tube. The fluorescent display tube according to claim 1, which has a temperature of ^-7 / ° C.