JPH0243088Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The invention is applicable to fluorescent display tubes that are incorporated into various electronic devices such as VTRs and clocks, and instrument panels of automobiles, and display characters, figures, etc. In particular, the present invention relates to a fluorescent display tube having a filament-like cathode with a long stretching distance.

[Prior art]

In recent years, fluorescent display tubes have attracted attention as self-luminous devices, and in addition to character and numeric displays, various display types such as graphic displays and combinations of these have been commercialized, and they are becoming larger and larger. It's down.

FIG. 5 shows an example of a conventional composite type fluorescent display tube, and FIG. 6 is a sectional view taken along line A--A in FIG. 5.

1 in the figure is a substrate made of an insulating material such as glass,
A wiring conductor 2a and an insulating layer 3 are formed on the upper layer by, for example, screen printing in accordance with a display pattern. Further, the insulating layer 3 has a plurality of through holes 3a that communicate with the wiring conductor 2a, and an anode conductor 2 on the upper surface thereof is connected to the wiring conductor 2a through a conductive material filled in the through hole 3a.
are laminated according to the display pattern. Reference numeral 4 denotes a phosphor having a desired luminescent color and disposed on the anode conductor 2, and the phosphor 4 and the anode conductor 2 form an anode portion.

In addition, 5 is coated with oxide on the surface and has a 600~
It is a filament-shaped cathode that emits thermoelectrons when heated to 700°C, and the cathode support 1
A plurality of electrodes are suspended between 2a and 12b with a predetermined tension to form a cathode section. Furthermore, a control electrode 7 is disposed between the filament-shaped cathode 5 and the substrate 1 in a state where it is fixedly held on a frame-shaped frame 6.

Further, 8 is a connection terminal electrically connected to the wiring conductor 2a, and 10 is a filament damper made of an insulating material, which is fixed to the control electrode 7 on the frame 6. 11 is a lead wire for supplying electricity to each electrode.

And an upper lid 9 consisting of a front plate 9a and a side plate 9b.
is fixed to the substrate 1 with a sealing material 13 such as low melting point fritted glass, the air inside the fluorescent display tube is exhausted from the exhaust pipe 14, and then the exhaust pipe 1 is
4 is sealed to maintain a high vacuum inside.

Since the fluorescent display tube has the above-described configuration, the electrons emitted from the filamentary cathode 5 are accelerated and controlled by the control electrode 7, and further selected by the anode conductor 2 and made to strike the phosphor 4. , to obtain the desired fluorescent display.

By the way, as mentioned above, with the diversification of fluorescent display tubes, for example, those with composite displays or those with a large number of display digits, large or dot-shaped anodes are arranged in multiple rows in the horizontal direction to form light emitting arrays. There is also an increasing demand for long fluorescent display tubes. Therefore, the length of the filament-like cathode 5 inevitably becomes longer. Therefore, the filament cathode 5
In this case, vibration occurs due to a change in the potential difference between the anode conductor 2 or the control electrode 7 and the filament-shaped cathode 5. In addition, the filament cathode 5
It resonates when it is pulse-driven or driven with alternating current, and it also resonates due to external vibrations that the fluorescent display tube itself receives, causing the filament-shaped cathode 5 to vibrate.

When the filamentary cathode 5 vibrates, the distance between the control electrode 7 and the filamentary cathode 5 changes, resulting in a difference in the strength of the electric field. Therefore, flickering of the display may occur, or in the worst case, the filament-like cathode 5 may come into contact with the control electrode 7 and cause the control electrode 7 to shoot.

Incidentally, the vibration of the filamentary cathode 5 can be reduced by increasing the tension applied to the filamentary cathode 5. However, the filament-like cathode 5 has a diameter of only a few tens of micrometers, and if the tension is increased, it is likely to break. For that purpose, Figure 5,
A filament damper 10 as a vibration isolating member as shown in FIG. 6 is disposed close to the filament cathode 5. Normally, the filament damper 10 is separated from the filament cathode 5, but when the filament cathode 5 vibrates, it comes into contact with the filament damper 10 to reduce the vibration.

The filament damper 10 is generally made of an insulating material such as mica, and is fixed by adhesive directly onto the frame 6 or onto the control electrode 7 welded to the frame 6. However, board 1
It is also possible to arrange it on the substrate 1 if there is sufficient space above. Further, the filament damper 10 may be formed of a metal material, but
In this case, it is necessary to insulate the filament damper 10 so that the filament-shaped cathode 5 and the control electrode 7, anode conductor 2, etc. do not shoot.

[Problem that the invention attempts to solve]

However, since the filamentary cathode 5 contacts the filament damper 10 and its vibration is reduced, the oxide on the surface is likely to peel off at the contact portion 5a where the filamentary cathode 5 contacts the filament damper 10. Further, heat is conducted from the contact portion 5a of the filament-shaped cathode 5 to the filament damper 10, and the contact portion 5a
The temperature of the filament cathode 5 is lower than that of other parts of the filament cathode 5 by several tens to hundreds of degrees. Therefore, near the contact portion 5a, the thermionic emission ability is significantly lower than in other portions of the filamentary cathode 5. Therefore, near the filament damper 10, uneven light emission of the phosphor 4 occurs, resulting in extremely poor visibility. Furthermore, even if there is sufficient space for installing the filament damper 10, uneven light emission occurs, which causes the problem that the filament damper 10 cannot be installed effectively in terms of preventing vibration of the filament cathode. It was hot.

[Means for solving problems]

The present invention was devised in view of the above-mentioned problems, and an object of the present invention is to provide a fluorescent display tube that can prevent vibration of the filament cathode even when the filament cathode is long and does not cause uneven light emission. shall be. In order to achieve the above-mentioned object, the configuration of the present invention is such that the cathode part that emits thermionic electrons is formed from a plurality of small cathode parts, and each of the small cathode parts has at least two or more filament-shaped cathodes adjacent to each other. and is stretched between a pair of cathode supports, and near each of the filament cathodes, vibration isolating members are arranged at different positions in the longitudinal direction of the adjacent filament cathodes. It is something that

〔Example〕

The present invention will be explained in detail below using the drawings.

FIG. 1 is a plan view showing an embodiment of the fluorescent display tube of the present invention, and FIG. 2 is a sectional view taken along the line BB in FIG. 1.

Reference numeral 21 in the figure is a substrate made of an insulating material such as a glass plate, and the upper surface has a wiring conductor 22a and an insulating layer 2.
3 are sequentially stacked. In addition, the insulating layer 23
In the upper layer, an anode conductor 22 electrically connected to the wiring conductor 22a through a through hole 23a is disposed in accordance with the display pattern.
A phosphor 24 of a desired luminescent color is arranged on the top,
The anode conductor 22 forms an anode portion. Further, 28 is a connection terminal connected to the wiring conductor 22a, and 31 is a connection terminal connected to the anode conductor 22a from the outside of the fluorescent display tube.
It is also a lead wire for supplying electricity to a control electrode 27 and a small cathode section 25, which will be described later.

Reference numeral 29 denotes an upper lid, which is formed by fixing a front plate 29a and a side plate 29b made of glass plates with a sealing material 33. Then, the sealing material 3 is attached to the substrate 21.
After sealing the upper lid 29 through the exhaust pipe 34
After that, the air inside the fluorescent display tube is exhausted, and then the exhaust pipe 34 is sealed to maintain the interior in a high vacuum state. A substrate 21 is placed above the substrate 21.
A cathode section consisting of three small cathode sections 25 is disposed between cathode supports 32a and 32b disposed on the upper surface. Each small cathode section 25 consists of two filament cathodes 25a, 25b stretched in close proximity between cathode supports 32a, 32b disposed on the upper surface of the substrate 21.
It is heated by the lead wire 31 and emits thermoelectrons. Further, a control electrode 27 is welded and fixed on a frame 26 between the substrate 21 and the small cathode section 25, and accelerates and controls the electrons emitted from the small cathode section 25 to make them strike the phosphor 24 to achieve a desired result. This provides a luminescent display.

Furthermore, 30a and 30b are filament dampers whose upper part is L-shaped, made of an insulating material such as mica, and fixed to the control electrode 27 on the frame 26 with an adhesive, with one end attached to the filament cathodes 25a and 25b. They are provided so as to be adjacent to or in contact with each other. The filament damper 30a includes a filament cathode 25a.
control electrode 2 slightly to the left of the center with respect to the tensioning direction.
7 and also a filament damper 30
b is arranged on the control electrode 27 slightly to the right of the center with respect to the stretching direction of the filament-shaped cathode 25b. That is, the filament cathodes 25a, 25
The contact portions 25a' and 25b' of b are located at different positions with respect to the stretching direction.

The filament cathodes 25a, 25
Even if vibration occurs for the reason described above, the filament cathodes 25a and 25b individually abut against the filament dampers 30a and 30b, thereby reducing the vibration. In this case, the contact portions 25a', 2
In the vicinity of 5b', the electron emission ability is significantly reduced due to heat being transferred to the filament dampers 30a and 30b and the temperature being lowered as described above. However, filamentary cathode 2
5a and 25b are arranged adjacent to each other, so for example, considering the broken line area C, the filament-shaped cathode 25a vibrates and comes into contact with the filament damper 30a, and the electron emission capability decreases significantly, causing electron emission to occur. Even if the capacity becomes zero, the filammetal cathode 25b in region C
is completely unaffected by the filament damper 30b and has sufficient electron emission ability. Therefore, the small cathode 25 in region C can always obtain at least 1/2 or more electron emission capability. In general, the electron emission ability of the small cathode section 25 is determined by the cathode current required for actual light emission, taking into account manufacturing variations in the filament cathodes 25a and 25b, deterioration during use, changes in usage conditions, etc. It is set at least several times higher. Therefore, one filament-like cathode 25a is connected to the filament damper 3.
Even if the electron emission ability of the small cathode part 25 is reduced to 1/2 due to contact with the small cathode part 25,
The cathode current necessary for display is sufficiently secured, and there is almost no unevenness in light emission during display.

[Other Examples]

In the above embodiment, a type of fluorescent display tube in which the display is observed from the filament cathode side has been described, but as shown in FIG. members can be applied. The substrate 41 is made of a light-transmitting insulating material such as a glass plate, and has a transparent conductive film or a striped pattern on the top depending on the display pattern.
A transparent anode conductor 42 made of an Al thin film or the like and a phosphor 43 are deposited in this order. Furthermore, 44 is a crossover layer, which is arranged according to the display pattern so that the internal electrodes do not interfere with the display.

A small cathode portion 45 is made up of a plurality of filament cathodes, and is stretched between supports 48, 48. Further, 46 is a frame that holds the control electrode 47. Note that the small cathode section 45 and the control electrode 4
6 is the same as in the previous embodiment. 49 more
is a filament damper made of an insulating material such as mica, and has several arms 49a (two in the embodiment).
and is fixed to a lid member 50 facing the substrate 41 with an adhesive 51. and lid member 5
0 is attached to the substrate 41 with a sealing material 52, and after exhausting the air inside with an exhaust pipe (not shown), the exhaust pipe is sealed and the inside is maintained in a high vacuum state.

As shown in the schematic plan view of FIG.
The arms 49a of the filament damper 49,
49a is in contact with or adjacent to the filament cathodes 45a, 45b. Even if vibration occurs in the filament cathodes 45a and 45b for the above-mentioned reason, the arms 49a and 45b individually
49a, vibration is reduced. Further, the arm 4 for the filament-like cathode portions 45a and 45b
Since the abutting portions 9a and 49a are located at different positions with respect to the stretching direction, considering the small cathode portion 45 as a whole, sufficient cathode current necessary for display is ensured, and almost no unevenness of light emission occurs in display. Furthermore, the board 41
Because it is a type of fluorescent display tube that can be observed from the side,
The filament damper 49 does not appear to affect the display at all, and in addition, although not shown, a shielding film for external electric fields is formed on the lid member 50, and the filament damper 49 is not connected to the substrate 41 or the control electrode 47. There are almost no positional restrictions compared to placing it on the top. Therefore, the filament damper 49 can be placed at the optimal position for vibration prevention regardless of the display pattern.

Further, in the above two embodiments, the small cathode section is formed of two filament-shaped cathodes, but it is more effective if it is formed of three or more filament-shaped cathodes. Furthermore, although only one filament damper was provided for each filament-like cathode, a plurality of filament dampers may be provided depending on the length of the filament-like cathode, the space in which the filament damper is arranged, etc.

Furthermore, the location of the filament damper is
Since it can be placed on either the substrate, the control electrode, or the lid member facing the substrate, it can be used depending on the observation type, such as a type in which the display is observed from the filament cathode side or a type of fluorescent display tube in which the display is observed from the substrate side. Or they can be used in combination. Furthermore, it goes without saying that the present invention can also be applied to display types such as a fluorescent display tube capable of displaying figures and images, a bar graph in which light-emitting anodes are arranged in ten to several dozen rows, and a dot array type fluorescent display tube.

〔effect〕

As described above, in the fluorescent display tube of the present invention, the small cathode portion that emits electrons is formed from a plurality of filament cathodes, and at least the vicinity of the adjacent filament cathodes is provided with shields at different positions in the longitudinal direction. This structure includes a filament damper, which is a vibration member. Therefore, even if one filament-shaped cathode that constitutes one small cathode comes into contact with the filament damper for vibration isolation and the electron emission ability decreases at that contact area, the small cathode can still be formed. The remaining filamentary cathodes have different contact points with the filament damper, so
The electron emission capability of one small cathode section as a whole does not decrease significantly.

Therefore, the cathode current (amount of electrons) required for light emission
can be obtained sufficiently, and even luminescence does not occur in the display. In addition, conventionally, when a filament damper was installed, the electron emission ability of the filament cathode was reduced, so it was placed in a position that would not affect the display as much as possible, so the vibration prevention function of the filament damper was fully utilized. However, in the fluorescent display tube of the present invention, it is only necessary to place the filament damper at an appropriate position, and the vibration prevention function of the filament damper can be fully demonstrated. It has excellent effects such as:

[Brief explanation of the drawing]

FIG. 1 is a plan view showing one embodiment of the fluorescent display tube of the present invention, FIG. 2 is a sectional view taken along line B-B in FIG. 1, and FIG. 3 is another embodiment of the present invention. FIG. 4 is a schematic plan view of FIG. 3, and FIG. 5 is a cross-sectional view showing
FIG. 6, a plan view showing a conventional fluorescent display tube, is a sectional view taken along line A--A in FIG. 5. 21, 41... Substrate, 22, 42... Anode conductor, 24, 43... Fluorescent material, 25, 45... Small cathode section, 25a, 25b, 45a, 45b... Filament shaped cathode, 25a', 25b' ...Contact part, 2
6... Frame, 27... Control electrode, 30a, 3
0b, 49...Filament damper, 32a,
32b, 48... cathode support.

Claims (1)

[Claims for Utility Model Registration] A fluorescent device that accelerates and controls electrons emitted from a cathode part using a control electrode and selectively impinges on the phosphor surface of an anode part formed on a substrate to obtain a desired luminescent display. In the display tube, the cathode section is formed from a plurality of small cathode sections,
In the small cathode, at least two or more filament-shaped cathodes are disposed in close proximity between a pair of cathode supports, and in the vicinity of each of the filament-shaped cathodes, with respect to the mutually adjacent filament-shaped cathodes, A fluorescent display tube characterized in that vibration isolating members are provided at different positions in the longitudinal direction.