JPH0887971A - Graphic fluorescent character display tube - Google Patents

Abstract

PURPOSE: To improve the brightness of a graphic fluorescent character display tube (display tube). CONSTITUTION: An external casing 1 is composed of a front plate 2, a back plate 3, and side plates 4. A plurality of stripe-like anodes 5 are formed in parallel one another in the inner face of the front plate 2. A plurality of linear control electrodes 9 are laid in parallel one another at right angles to the anodes 5 above the anodes 5. A cathode 11 is laid in the inner face of the back plate 3. The control electrodes 9 are made of an alloy containing 56% of Ni, 44% of Ti, and a slight amount of Cu and Co. Of the alloy, the elastic limit is 6%, the coefficient of thermal expansion is 110×10<-7> / deg.C. The conversion of the elastic limit into temperature gives 0.06/(110×10<-7> / deg.C)=5454 deg.C. Tensile force is applied previously to the control electrodes to elastically expand the electrodes by necessary degree and fix the electrodes, so that no control electrode loosen even if the temperature of the control electrodes rises at the time of driving a fluorescent display tube. As a result, driving voltage for the control electrodes of the display tube is not limited practically. The brightness of the display tube increases proportionally to about 2.7 power of driving voltage of the control electrodes. Consequently, a display tube with high brightness can be provided and control electrodes are prevented from vibrating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a graphic fluorescent display tube having a plurality of linear control electrodes made of superelastic material.

[0002]

2. Description of the Related Art FIG. 2 is a sectional view showing an example of a graphic fluorescent display tube. The envelope 1 includes a light-transmitting front plate 2, a rear plate 3 facing the front plate 2, a front plate 2 and a rear plate 3.
And a side surface plate 4 provided between the outer peripheral portions thereof are sealed together to form a box shape. The inside of the envelope 1 is kept in a high vacuum state.

On the inner surface of the front plate 2 of the envelope 1, a plurality of strip-shaped anodes 5 are provided in parallel with each other at a predetermined interval. Each anode 5 is composed of a band-shaped light-transmissive anode conductor 6 provided on the inner surface of the front plate 2 and a phosphor layer 7 deposited on the upper surface of the anode conductor 6. Envelope 1
Above the anode 5 therein, a plurality of linear control electrodes 9 are stretched in parallel with each other at predetermined intervals via a spacer 8. The longitudinal direction of each control electrode 9 is orthogonal to the longitudinal direction of the anode 5. Both ends of each control electrode 9 penetrate the sealed portion of the envelope 1 in an airtight manner and are drawn out of the envelope 1. A linear cathode 11 serving as an electron source is provided on the inner surface of the back plate 3 in the envelope 1 via a mounting frame 10.
Is stretched.

Conventionally, as a material forming the control electrode 9, an alloy (426 alloy) having a composition of 42% Ni, 6% Cr and the balance of Fe, or stainless steel such as SUS430 has been used. . Since the 426 alloy has good compatibility with glass, the control electrode 9 penetrating the sealed portion of the envelope 1
Suitable as a material. However, since the narrow portion of the control electrode 9 penetrates the sealed portion of the envelope 1, not only 426 alloy is necessarily used, but SUS430 or the like having high elasticity may be used.

In order to drive the graphic fluorescent display tube, a scanning signal is simultaneously applied to two adjacent control electrodes 9 and the scanning electrodes are sequentially moved one by one to perform scanning. A display signal is given to the anode 5 in synchronization with the scanning of the control electrode 9. A region surrounded by the strip-shaped anode 5 and the two control electrodes 9, 9 orthogonal to the strip-shaped anode 5 serves as a unit light emitting region, and an arbitrary image display is performed by a set of the selected unit light emitting regions.

[0006]

The metal material used for the control electrode of the conventional graphic fluorescent display tube has an elastic limit of about 0.3% at most. The control electrode has a predetermined size so as not to expand and loosen when it is heated by a control current when the graphic fluorescent display is driven, or when it is heated by the heat of the anode by the anode current or the heat of the hot cathode. The tension is applied to the envelope to stretch it, and both ends are fixed. The temperature at the time of thermal expansion corresponding to the elastic limit elongation amount is calculated as follows based on the thermal expansion coefficient of each material.

0.003 / (80 × 10 ^-7 / ° C.) = 37
5 ° C. (for 426 alloy) 0.003 / (110 × 10 ⁻⁷ / ° C.) = 273 ° C. (S
In the case of US430) That is, in the case of the conventional 426 alloy, the mechanical strength is maintained up to 375 ° C, and in the case of SUS304, the mechanical strength is maintained up to 273 ° C.

However, from the fact that it is necessary to consider the safety factor, the conventional graphic fluorescent display tube is designed so that the temperature rise allowed for the control electrode during driving is 200 ° C. or less. If the temperature rise allowed for the control electrode is within this range, the voltage applied to the control voltage will be restricted accordingly, and a high voltage cannot be applied, and the graphic fluorescent display tube is inevitable. There was a limit to the brightness.

However, since the conventional graphic fluorescent display tube is used for a display device of a computer terminal or a measuring instrument, it is sufficient that the graphic fluorescent display tube has a brightness enough to obtain appropriate visibility in the room. Therefore, as described above, even if the control voltage is limited due to the material of the control electrode and there is a limit to high brightness, it can be used as long as it is used for the above purpose, and it is necessary to solve the problem that high brightness cannot be achieved It was never recognized as a problem.

However, recently, a graphic fluorescent display tube has been studied as a display device for car navigation. For automotive use, bright sunlight in the daytime and sunlight in the morning and evening may directly illuminate the display surface of the graphic fluorescent display tube.In such a case, in order to ensure sufficient visual recognition, the graphic It is necessary to sufficiently increase the brightness of the light emitting portion of the fluorescent display tube and to combine a filter having a low light transmittance. Also, the instrument panel of the car in which the graphic fluorescent display tube is installed is located near the engine, and heat and vibration of the engine adversely affect the linear control electrodes of the graphic fluorescent display tube such as vibration. It is also necessary to apply tension to the control electrode so as to prevent vibration.

However, in the conventional graphic fluorescent display tube, due to the restriction of the material of the control electrode as described above, it is not possible to apply a control voltage such that the control electrode has a temperature of 200 ° C. or higher, and sufficient tension may be applied. Since it was not possible, a high-luminance graphic fluorescent display tube for a vehicle could not be realized.

An object of the present invention is to improve the brightness of a graphic fluorescent display tube having a large number of linear control electrodes so that it can be applied to a vehicle.

[0013]

According to a first aspect of the present invention, there is provided a graphic fluorescent display tube including an anode having a phosphor, a cathode, and a plurality of control electrodes stretched with a predetermined tension. In the graphic fluorescent display tube inside, the control electrode is made of a super elastic material.

The graphic fluorescent display tube according to a second aspect of the present invention is the graphic fluorescent display tube according to the first aspect, in which deformation caused by heat generated during operation of the graphic fluorescent display tube is greater than a thermal expansion amount generated in the control electrode. It is characterized in that a tension to be generated is applied to the control electrode in advance.

A graphic fluorescent display tube according to a third aspect of the present invention is the graphic fluorescent display tube according to the first aspect, wherein the elastic limit of the superelastic material is 0.5% or more.

According to a fourth aspect of the present invention, there is provided the graphic fluorescent display tube according to the first aspect, wherein the superelastic material is a Ni-Ti alloy.

[0017]

[Function] A superelastic material having an elastic limit of 0.5% or more,
If a superelastic material such as Ni-Ti alloy is used as the material for the control electrode of the graphic fluorescent display tube, the control electrode is provided with an expansion amount larger than that of the graphic fluorescent display tube mounted on the vehicle which is expanded by the heat generated during operation. Since it can be attached by pulling, it is possible to realize the high brightness required for a graphic fluorescent display tube mounted on a vehicle and prevent vibration of the control electrode.

[0018]

The structure of the graphic fluorescent display tube according to the present invention is the same as the conventional one, but the material of the control electrode is different from the conventional one. The control electrode of the graphic fluorescent display tube of the present embodiment is made of a superelastic material having an elastic limit of 0.5% or more,
It is made of a superelastic alloy such as a Ni-Ti alloy. Table 1 shows examples of superelastic alloys that can be applied as the material of the control electrode in this example. In the table,% is% by weight.

[0019]

[Table 1]

The various alloys shown in Table 1 are known as shape memory alloys. In order to bring out the shape memory effect in these alloys, as shown in FIG. 3, first, the required shape is memorized in the high temperature phase, and after cooling to below the martensite transformation start point Ms, transformation is performed. When heated next, it starts to return to the original memorized shape from the reverse transformation start point As, and completely returns to the original shape at the reverse transformation end point As. This is the shape memory effect due to the so-called thermoelastic martensitic transformation. On the other hand, even in the parent phase having the reverse transformation end point Af or more, it is possible to cause the martensitic transformation by the application of stress. This is the deformation due to the stress-induced martensitic transformation, but when the stress is removed, it returns to the original matrix phase, so the given deformation disappears and returns to the original state. This is a so-called superelastic effect. For example, Ni
In the case of -Ti alloy, even if a deformation of up to 10% is applied, the original state is completely restored after the stress is removed.

For example, as a super elastic material, the composition is 56% N
The control electrode is manufactured by using an alloy of i, 44% Ti with a slight addition of Cu or Co. The elastic limit of this alloy is 6%, and the coefficient of thermal expansion is 110 × 10 ⁻⁷ / ° C. When this elongation is converted to temperature, it becomes 0.06 / (110 × 10 ⁻⁷ / ° C.) = 5454 ° C. That is, tension is applied to the control electrode in advance so that the control electrode is elastically stretched by a necessary amount so that slack does not occur in the control electrode even if the temperature rises in the control electrode when driving the graphic fluorescent display tube. It can be fixed in the state.

If this temperature rise can be endured, it can be said that the drive voltage of the control electrode of the graphic fluorescent display tube is virtually unlimited. As shown in FIG. 1, the brightness of the graphic fluorescent display tube increases in proportion to the drive voltage of the control electrode raised to the power of 2.7. A graphic fluorescent display tube can be realized.

[0023]

In the graphic fluorescent display tube of the present invention, since the linear control electrodes are made of a superelastic material, the control electrodes can be tensioned so as to withstand the high temperature during operation. Therefore, a high voltage or power can be applied to the control electrode, and a high-luminance graphic fluorescent display tube useful for in-vehicle use can be realized. Further, vibration of the control electrode can be prevented.

[Brief description of drawings]

FIG. 1 is a graph showing a relationship between brightness and a voltage of a control electrode in a graphic fluorescent display tube.

FIG. 2 is a cross-sectional view showing an example of the structure of a graphic fluorescent display tube.

FIG. 3 is a graph showing a relationship between temperature and electric resistance of a superelastic alloy, showing respective transformation points of the alloy.

Claims (4)

[Claims] 1. A graphic fluorescent display tube having an anode having a phosphor, a cathode, and a plurality of control electrodes stretched with a predetermined tension inside an envelope, wherein the control electrode is a superelastic material. A graphic fluorescent display tube characterized by being composed of. 2. The tension is applied to the control electrode in advance so that the control electrode is deformed by the heat generated during the operation of the graphic fluorescent display tube so as to be deformed by more than the thermal expansion amount. Graphic fluorescent display tube. 3. The graphic fluorescent display tube according to claim 1, wherein the elastic limit of the superelastic material is 0.5% or more. 4. The graphic fluorescent display tube according to claim 1, wherein the superelastic material is a Ni—Ti alloy.