JPH08138592A - Fluorescent display tube - Google Patents

Abstract

PURPOSE: To provide favorable light emission characteristic even if an ineffective part is made small by enabling cathode structure to be formed easily. CONSTITUTION: Display elements 6, where transparent display electrodes 4 and phosphor layers 5 are overlaid on the display electrodes, are arranged in plural numbers in the shape of a matrix on the inner face of the translucent front glass 1 constituting a vacuum container 3. This fluorescent display tube is constituted, being provided further with selective electrodes 8 arranged in matrix form, corresponding to the disposition of the display elements 6, a plurality of coil-shaped cathodes 14 larger in cathode emission capacity per unit area or length, and a diffusion electrode 15 which widens the electrons emitted from this coil-shaped cathode 14 to the side of the display element 6.

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 applied as an image display device, and in particular, it is formed by arranging a plurality of display elements along the X and Y directions, and has a light emitting surface formed of a phosphor. The present invention relates to a transmissive fluorescent display tube of a type that allows transmission and observation.

[0002]

2. Description of the Related Art Generally, fluorescent display tubes are classified into a reflective type in which a fluorescent substance light emitting surface is directly observed and a transmissive type in which a fluorescent substance is transmitted for observation. It is the back surface side in the mold, and the display surface side in the transmission type. The reflection type fluorescent display tube has a feature that high brightness can be obtained as compared with the transmission type because the light emitting surface is directly observed.The transmission type fluorescent display tube has a large viewing angle because the light emitting position is close to the front surface. ,
It is characterized by good display quality. The present invention relates to this transmission type fluorescent display tube.

FIG. 4 is an enlarged sectional view of an essential part for explaining the structure of this type of fluorescent display tube. In FIG. 4, the translucent front glass plate 1 and the non-translucent back plate 2 which are opposed to each other sandwich a side face plate (not shown) formed in the peripheral portion, and are sealed by seal glass to form a vacuum. The container 3 is configured.
The side plate may be integrally formed with the front glass plate 1 or the rear plate 2 or may be used as a seal glass. The external terminal is taken out through this seal glass.

On the inner surface side of the front glass plate 1, a display electrode 4 and a phosphor layer 5 placed on the display electrode 4 are adhered to form a display element 6, and the rear plate 2 is formed. A filamentary hot cathode 7 suspended and supported, and a selection electrode 8 formed between the filamentary hot cathode 7 and the display element 6 are arranged in a space formed between the filament hot cathode 7 and the display element 6. It constitutes a triode vacuum tube structure.

Here, the display electrode 4 constituting the display element 6 is a transparent electrode formed of a transparent material such as ITO or a blind or mesh shape that can transmit the light emitted from the phosphor layer 5 through the front glass plate 1. An electrode having an opening is used.

The selection electrode 8 for controlling the electron path is arranged at a position where it does not prevent the electrons emitted from the hot cathode 7 from reaching the display portion, but it is in the shape of a grid or a mesh so that the electrons can pass through. It is formed into a shape. A matrix is formed of wirings to which a plurality of display electrodes 4 are connected in order to drive a large number of display elements 6 with a small number of electrode terminals, and selection electrodes 8 common to the plurality of display electrodes 4 in a direction intersecting with the display electrodes 4. Configured and addressed.

The hot cathode 7 is usually a filamentary tungsten thin wire having an emitter material deposited on the surface thereof. Since the hot cathode 7 is an ultrafine wire, it does not interfere with the display even if it is a reflective fluorescent display tube. The hot cathode 7 is suspended and supported so as not to loosen the aerial portion in order to provide an appropriate space from the display electrode 4 and the selection electrode 8 or for heat separation. Therefore, columns for determining the height of the hot cathode 7 from the front glass plate 1 and springs for applying tension are used.

FIG. 5 is an enlarged sectional view of an essential part for explaining the suspension structure of the conventional filamentary hot cathode 7. In FIG. 5, a pair of metallic columns 9 and 10 having an L-shaped cross section are fixedly arranged at both ends on the inner surface side of the front glass plate 1. The height is defined by inserting the hot cathode 7 at the tip. The filamentary hot cathode 7 has one end side welded and fixed to the leg portion of one of the columns 9 at a position indicated by a point P1, and the other end side of the leaf spring 11 fixedly arranged to the leg portion of the other column 10. Is welded and fixed at a position indicated by a point P2 to give tension. The pair of columns 9 and 10 for suspending and supporting the filamentary hot cathode 7 may be provided on the back plate 2 or a side plate (not shown).

Even in the filamentary cathode 7 heated to the operating temperature, the ends thereof are conduction-cooled through the contact points of the pillars, and the cooling portion CS shown in the figure is below the operating temperature. The length of the cooling part CS is usually about several mm, but since electrons are not emitted, it forms an invalid display part. of course,
The portions between the tips of the struts 9 and 10 and the welding points P1 and P2 and the formation portion of the leaf spring 11 are also invalid display portions. That is,
The area between the two cooling parts CS is the effective display portion HS, and the other portions are the invalid display portions. The shorter the length of the filamentary hot cathode 7, the larger the proportion of the invalid display portion.

In a tile type image display device in which a large number of fluorescent display tubes having display elements 6 arranged in the X and Y directions are arranged to form a screen, an invalid display section from the display section to the tube wall determines the dot pitch. That is, since the dot pitch becomes coarser as the length of the invalid display portion becomes longer, this is particularly important in this type of fluorescent display tube.

The electrons emitted from the filamentary hot cathode 7 are spread according to the area of the anodes which are the display electrodes 4 and the selection electrodes 8. Therefore, in order to ensure the display, the shape of the selection electrode 8 is selected so as to cover the display electrode 4. However, even if the anode area is increased, the uniform electron diffusion region does not become infinitely large. In the case of a flat anode, the range of a radius of 5 to 10 times the distance from the position closest to the hot cathode 7 is the limit of the uniform diffusion region. Also,
Since the display electrodes 4 and the selection electrodes 8 which are address electrodes are limited in display pattern and pitch, there are also restrictions in their areas.

Further, even when the area of the address electrode and the distance between the cathodes are increased without restriction on the area, the following disadvantages are pointed out. Since the address voltage increases as the distance between the cathodes increases, the load on the driving element for addressing increases. Also, because it diffuses the electrons over a large area,
The burden of cathode power is large. Since the conventional filamentary hot cathode 7 has a small surface area, the amount of emitter material that can be deposited is limited. Therefore, the brightness and lifetime determined by the consumption of this emitter material are limited.

In order to solve such a restriction, the distance between the address electrode and the cathode is shortened to a few mm or less to reduce the driving load, and a plurality of filaments are arranged at short intervals to widen a uniform display area. The conventional structure is one in which the cathodes 7 are installed in parallel.

[0014]

As described above, in the conventional fluorescent display tube, much labor is required to form the filamentary hot cathode 7, and the invalid display portion is also large. Further, if the number of invalid display portions is reduced, there are problems such as a restriction on display patterns, an increased load on driving elements, and a reduction in brightness and life.

Therefore, the present invention has been made in order to solve the above-mentioned conventional problems, and an object thereof is to easily form a cathode structure and obtain good light emission characteristics even if the invalid display portion is made small. The present invention provides a fluorescent display tube.

[0016]

In order to achieve such an object, a fluorescent display tube according to the present invention emits from a hot cathode having a large amount of cathode emitter material per unit area or length and a hot cathode. And a diffusion electrode for spreading electrons to the display electrode side.

[0017]

In the fluorescent display tube according to the present invention, electrons emitted from a relatively small hot cathode reach the display electrode on which the phosphor layer is formed by spreading the electron path by the diffusion electrode.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1A and 1B are views for explaining the configuration of an embodiment of a fluorescent display tube according to the present invention. FIG. 1A is a plan view of a main part, and FIG. 1B is a sectional view taken along line BB 'in FIG. 1A. It is a cross-sectional view, and the same parts as those in the above-mentioned drawings are denoted by the same reference numerals. In FIG. 1, a pair of metallic columns 12, 13 each having an L-shaped cross section are fixedly arranged on the rear plate 2 with a predetermined distance therebetween. The direct heating type cathode 14 formed in a coil shape has both terminal portions fixedly arranged by, for example, an electric welding method.

The cathode 14 is formed by coating a tungsten wire formed into a double coil with an emitter material, and has a coil diameter of about 1 mm and a coil length of about 10 mm.
It has the size of. By forming the cathode 14 into a double coil structure, it is possible to coat the emitter about 100 times or more as compared with a filament having a length of about 10 mm. As a matter of course, the mounting positions of the columns 12 and 13 are arranged at positions where they do not obstruct the electron path from the cathode 14 to the display electrode 4.

The selection electrode 8 and the first diffusion electrode 15 formed between the cathode 14 and the display electrode 4 are processed into, for example, a blind shape or a mesh shape so as to have an opening through which electrons can pass. Is formed. The selection electrode 8 is
As shown in FIG. 1A, a structure that covers the phosphor pattern formed of the phosphor layer 5 is preferable, and the first diffusion electrode 15 preferably has a structure that covers the entire display portion formed of a large number of display elements 6.

The degree of diffusion of electrons emitted from the cathode 14 depends on the distance between the cathode 14 and the first diffusion electrode 15 and the electrode area of the first diffusion electrode 15. The larger the distance and the larger the area, the larger the area where electrons can be uniformly emitted. For example, in the case of the first diffusion electrode 15 having a structure that covers the entire surface of the display unit as shown in FIG. 1B, a region having a radius of about 5 to 10 that is the distance between the cathode 14 and the first diffusion electrode 15. Uniform diffusion is possible with. Accordingly, in order to deal with a wider display section, a plurality of coiled cathodes 14 may be arranged, and they can be connected in parallel and driven by the same power source.

In such a structure, the cathode 14 is supplied with electric power for heating to the operating state, and at the same time, a predetermined potential is applied to each of the display, selection and diffusion electrodes. As described above, if the distance between the cathode 14 and the first diffusion electrode 15 is increased in order to spread the diffusion of electrons, the voltage applied to the first diffusion electrode 15 also needs to be large. However, it is sufficient for the first diffusion voltage 15 to have one system for all the display elements 6, so that the driving load is small. The address voltage applied to the display electrode 4 and the selection electrode 8 may be set based on the voltage of the first diffusion electrode 15. Further, if the distance between these electrodes is reduced, the burden on the address driving element, which is required in large numbers, can be made the same as in the conventional case.

According to this structure, by forming the cathode 14 in a coil shape, heating can be facilitated and a large amount of emitter material can be applied, so that the cathode emitter amount can be increased. You can That is, the double coil is preferable to the single coil, and the triple coil is preferable to the double coil. The more the multiple coils are, the more the cathode emitter amount can be increased. Also, the cathode 1
Since 4 is formed in a coil shape, since it has an elastic force, it is possible to omit a leaf spring or the like, which is particularly required in the conventional structure, which simplifies the manufacturing work, and reduces the coil length against vibration and impact. If it is about 10 mm or less, there is no problem, and since there is the first diffusion electrode 15, there is no need for a coil length longer than that.

Further, as another embodiment of this embodiment, even if the arrangement positions of the selection electrode 8 and the first diffusion electrode 15 are exchanged in the vertical direction and they are arranged opposite to each other, the same effect as described above is obtained. Is obtained.

(Embodiment 2) FIG. 2 is an enlarged sectional view of an essential part for explaining the construction of a fluorescent display tube according to another embodiment of the present invention. The same parts as those in FIG. There is. 2 is different from FIG. 1 in that
In addition to the diffusion electrode 15 of FIG. 1, a second diffusion electrode 16 made of a conductive film is formed on the back plate 2 by deposition. These two
The first diffusion electrode 15 and the second diffusion electrode 16 are
The same voltage may be applied or different voltages may be applied.

In such a structure, the cathode 14 is shown in FIG.
Similarly to the above, a double coil structure is used, and the distance between the cathode 14 and the first diffusion electrode 15 and the second diffusion electrode 16 in the direction perpendicular to the display surface is set to 10 mm. When the display element 6 is made to emit light with one cathode 14, a radius of about 70 m
A uniform display was obtained in the range of m. When driving a light emitting region of the same extent as this, it is necessary to hang about 10 in parallel in the conventional fluorescent display tube using the filament cathode 7.

In addition, the first embodiment as another embodiment of this embodiment
Even if the diffusion electrode 15 is not provided and only the second diffusion electrode 16 is provided on the back plate 2, the same operational effect as described above can be obtained. In this case, the first diffusion electrode 15 is the cathode 14
Since it is formed closer to the display electrode 4, the electron diffusion effect is larger than that of the second diffusion electrode 16 formed on the opposite side. However, this difference is not so large, so the second diffusion 1
It is possible to use only 6 and, of course, if both are used together, the electron diffusion effect is the largest. In addition, since the second diffusion electrode 16 can be deposited on the back plate 2, the second diffusion electrode 16 can be easily formed, but the first diffusion electrode 15 that must be disposed in the hollow requires much labor. Therefore, the selection of these diffusion electrodes may be determined in consideration of the characteristics and the ease of formation.

(Embodiment 3) FIG. 3 is a diagram showing the construction of a fluorescent display tube according to still another embodiment of the present invention.
3A is a plan view of a main part, and FIG. 3B is B- in FIG. 3A.
It is a cross-sectional view taken along the line B ', and the same parts as those in the above-mentioned drawings are denoted by the same reference numerals. 3 is different from FIG. 2 in that
The display electrodes 4 constituting the display elements 6 arranged in the X and Y directions with respect to the display surface shown in FIG. 2 are commonly connected and formed, and also serve as the third diffusion electrode 17. The third diffusion electrode 17 is formed on the entire display surface on the inner surface side of the front glass plate 1 by a transparent material such as ITO.

Below the display element 6, a first selection electrode 81 and a second selection electrode 82 are arranged in a direction intersecting with each other.
And a selection electrode 8 composed of two types of electrode groups. In this case, the first selection electrode 81 is arranged directly below the phosphor layer 4, and the portion where the two selection electrodes 81 and 82 intersect is the phosphor layer when viewed from the observation direction. Covering 5 is desirable.

According to this structure, the electrons radiated from the cathode 14 and reaching the third diffusion electrode 17 are controlled by the first selection electrode 81 and the second selection electrode 82,
Since this address voltage may be the same as or lower than the conventional one, the circuit load can be reduced. On the other hand, the third diffusion electrode 17 is formed as a so-called solid electrode on the entire inner surface of the front glass plate 1 and is a single system, so that the circuit load does not become so large even when driven at a high voltage. Third diffusion electrode 17
If the power consumption is the same, high-luminance light emission can be obtained by using a high voltage in a short time rather than displaying a low voltage for a long time.
Therefore, in a fluorescent display tube having a large number of time divisions, it is desirable to drive the third diffusion electrode 17 at a high voltage.

If the selection electrode 8 has a large area with respect to the cathode 14, the third diffusion electrode 17 can be omitted, but this makes fine display difficult. Considering the dot pitch arranged in the X and Y directions, it is about 2 mm, especially about 1 m.
The third diffusion electrode 17 is indispensable at a pitch of m or less.

It is known that one select electrode group is divided into a plurality of groups for multiple addressing. For example N ×
The dual address is a method in which the selection electrode group formed by M lines is matrix-driven by M groups connected every N display elements and N groups connected by M continuous display elements. This embodiment can be realized by dividing the third diffusion electrode (display electrode) 17 into N pieces and connecting every N pieces of selection electrodes 8 in the same direction as the divided direction. Of course, if the divided group is further divided, it becomes a multiple address.

In the above-described embodiment, the case where the direct heating type coiled cathode 14 is used as the cathode has been described, but the present invention is not limited to this, and is composed of a cathode and a heater. The same effect as described above can be obtained by using the indirectly heated cathode. Although the indirectly heated cathode has a complicated cathode structure, it has an advantage that the potential of energization heating does not affect the display voltage. Further, the indirectly heated cathode is preferably a cathode of a type in which a porous metal is impregnated with an emitter material. Further, since the large amount of emitter material can be applied to the indirectly heated cathode, long life can be obtained even when the current is increased and the rigidity is high, so that it is not necessary to use a leaf spring for applying tension. In addition, for the indirectly heated cathode, only one column is required,
It is installed at a position avoiding an electron path toward the display electrode 4.

[0034]

As described above, according to the present invention,
By providing a cathode with a large emitter deposition amount per unit area or length and a diffusion electrode for increasing the electron emission diffusion from this cathode, it is possible to display a large area uniformly with a small cathode. Further, since the cathode may be small and a cathode having high rigidity or a coiled cathode having elasticity can be selected, it is not necessary to form a leaf spring having elasticity. Therefore, the number of cathodes can be reduced as well as the labor for forming the cathodes is small. Furthermore, if the number of cathodes is small,
The heat dissipation from the pillars is also small, so the power consumption is low. Also, since there is no invalid display area due to columns etc.,
The fluorescent display tube can be made small and a fine tile type fluorescent display tube can be obtained. Further, when the diffusion electrode is used as the display electrode, the driving load is small even if the voltage is high and the brightness is high. Furthermore, since conventional manufacturing techniques can be applied, extremely excellent effects such as simplification of manufacturing can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration according to an embodiment of a fluorescent display tube according to the present invention.

FIG. 2 is an enlarged cross-sectional view of an essential part showing the configuration of another embodiment of the fluorescent display tube according to the present invention.

FIG. 3 is a diagram showing a structure of a fluorescent display tube according to another embodiment of the present invention.

FIG. 4 is an enlarged sectional view of an essential part showing the structure of a conventional fluorescent display tube.

FIG. 5 is an enlarged sectional view of an essential part for explaining a suspension structure of a filament cathode of a conventional fluorescent display tube.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Front glass plate, 2 ... Back plate, 3 ... Vacuum container, 4 ... Display electrode, 5 ... Phosphor layer, 6 ... Display element, 7 ... Cathode, 8 ...
Select electrode, 81 ... First select electrode, 82 ... Second select electrode, 9 ... Strut, 10 ... Strut, 11 ... Leaf spring, 12 ... Strut, 13 ... Strut, 14 ... Coiled cathode, 15 ... First Diffusion electrode, 16 ... second diffusion electrode, 17 ... third diffusion electrode.

Claims (4)

[Claims] 1. A display element is a matrix comprising a translucent display electrode adhered to the inner surface of translucent glass constituting a vacuum container and a phosphor layer adhered to the display electrode. A display unit arranged in a pattern, a hot cathode arranged to face the display unit, a selection electrode for controlling the electrons emitted from the hot cathode reaching the display electrode, and emitted from the hot cathode. And a diffusion electrode that spreads the direction of electrons to the display unit. 2. The fluorescent display tube according to claim 1, wherein the hot cathode is a coiled cathode. 3. The fluorescent display tube according to claim 1 or 2, wherein the diffusion electrode is arranged closer to the display unit side than the hot cathode. 4. The fluorescent display tube according to claim 1, 2 or 3, wherein the display electrodes are commonly connected between the display elements and also serve as diffusion electrodes.