JPH103870A - Fluorescent character display tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an interval between a filament shaped cathodes more than conventional one in a fluorescent character display tube structured so that plural filament shaped cathodes are stretched in parallel to each other between an anchor and a support. SOLUTION: Plural first filaments 2a are stretched at specified pitches between a first anchor 8a and a first support 9a of a pair of first cathode support bodies 3a and 4a coupled. Plural second filaments 2b are expanded at the same pitches between a second anchor 8b and a second support 9b of a pair of second cathode support bodies 3b and 4b coupled. The second cathode support bodies 3b and 4b are arranged inside the first cathode support bodies 3a and 4b, and both filaments 2a and 2b are combined by shifting them at half pitch in the direction orthogonal to the longitudinal direction and arranged on an anode substrate 1. The pitches of the filaments are smaller than conventional one, and the luminous brightness of the anode is improved. Both anchors 8a and 8b are on the same side relevant to the longitudinal direction of both filaments, both filaments thermally expanded are moved in the same direction, they do not come into contact with each other without their intervals changed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filamentary cathode of a fluorescent display tube, and more particularly to a fluorescent display tube having a plurality of filamentary cathodes stretched at a smaller pitch than in the prior art.

[0002]

2. Description of the Related Art A general fluorescent display tube has an envelope maintained in a high vacuum atmosphere. In general, an envelope is constructed by assembling a plurality of glass substrates into a box shape with sealing glass. Inside the envelope, an anode having a phosphor layer is formed on an anode substrate which is a part of the glass substrate, a control electrode is provided above the anode, and an electron is provided above the control electrode. A filament-shaped cathode (hereinafter, abbreviated as a filament) that emits helium. The electrons emitted from the cathode are controlled by the control electrode and strike the anode to cause the phosphor layer to emit light.

[0003] As shown in FIG.
Is stretched between the anchor 101 and the support 102. The anchor 101 has a leaf spring-like arm formed by bending a stamped plate material, and one end of the filament 100 is fixed to apply tension to the filament. The other end of the filament 100 is fixed to the support 102. A cathode support 103 to which a plurality of anchors 101 are welded at a predetermined pitch, and a cathode support 104 to which a plurality of supports 102 are welded at a predetermined pitch, have a frame 105.10.
6, a plurality of filaments 100 are stretched with tension applied between a plurality of pairs of anchors 101 and supports 102.

As shown in FIG. 5, cathode supports 103 and 104 connected in a frame shape are positioned with respect to an anode substrate 107, and are connected to an anode (not shown) and a control electrode (not shown) formed on the anode substrate 107. The position of the filament 100 is determined. On the anode substrate 107, the cathode support 103,
The box-shaped container portion is sealed with the external leads 108 and the like 104 interposed therebetween.

[0005]

The fluorescent display tube is also used for a vehicle. In the case of an in-vehicle fluorescent display tube, if it can be directly driven at 12 V, it is not necessary to provide a circuit for voltage adjustment or the like, and it is advantageous in terms of cost. In addition, a fluorescent display tube for use in a vehicle needs to have sufficient luminance so that the fluorescent display tube can be reliably viewed even in the daytime. In order to obtain sufficient luminance at such a low anode voltage, it is necessary to increase the cathode current by improving the emission from the cathode. In order to increase the cathode current while reducing the load per filament, it is necessary to reduce the interval between the stretched filaments and increase the number of filaments.

However, in a conventional structure in which a plurality of filaments are stretched between a pair of cathode supports each having an anchor and a support fixed at predetermined intervals, the interval between the cathodes arranged in parallel is reduced due to a design problem. Could not be smaller than a certain. That is, the height of the arm required to provide the required resiliency to the arm of the anchor, the thickness of the support portion of the arm required to provide the required strength at the root of the arm of the anchor, etc. Is considered, the distance between the anchors is at least 1.5 in the conventional structure.
mm or more, and the pitch of the cathode could not be further reduced.

An object of the present invention is to provide a fluorescent display tube having a structure in which a plurality of filamentary cathodes are stretched in parallel with each other between an anchor and a support, in which the distance between the filamentary cathodes is made smaller than before.

[0008]

According to a first aspect of the present invention, there is provided a fluorescent display tube comprising: a first cathode support having a plurality of first anchors and a plurality of first supports arranged in pairs; A plurality of first filamentary cathodes stretched at a predetermined pitch between the first anchor and the first support so as to be substantially parallel to each other, and a position close to each of the first anchors. A second cathode support in which a plurality of second anchors arranged in a plurality and a plurality of second supports arranged in positions close to the respective first supports are arranged in pairs; and the first filamentary cathode is The second anchor and the second anchor disposed in pairs at substantially the same pitch and at substantially the same pitch as the first filamentary cathode;
It is characterized by having a plurality of second filamentary cathodes stretched close to the respective first filamentary cathodes between the supports.

According to a second aspect of the present invention, in the fluorescent display tube of the first aspect, a DC voltage is applied to the first filament cathode and the second filament cathode. .

According to a third aspect of the present invention, in the fluorescent display tube according to the second aspect, the second anchor and the second support are inside the first anchor and the first support, The second filament cathode is shorter than the first filament cathode.

According to a fourth aspect of the present invention, there is provided the fluorescent display tube according to the second aspect, wherein the second anchor comprises:
The first anchor is inside the first support and the second support is outside the first support.

According to a fifth aspect of the present invention, in the fluorescent display tube of the third aspect, the DC voltage applied to the first filament cathode and the second filament cathode is substantially the same. The first filament cathode has a larger weight per unit length of the filament cathode than the second filament cathode.

According to a sixth aspect of the present invention, there is provided the fluorescent display tube according to the second aspect, wherein a DC voltage applied to the first filamentary cathode and a DC voltage applied to the second filamentary cathode are applied. The DC voltage is provided by two independent DC power supply circuits, and each DC power supply circuit can be opened and closed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. The fluorescent display tube of the present example has a box-shaped envelope held in a high vacuum atmosphere. The envelope is formed by sealing a box-shaped container part having an open lower surface on the upper surface of the rectangular anode substrate 1 shown in FIG. Although not shown, an anode having a phosphor layer is formed on the anode substrate 1 inside the envelope, and a control electrode is provided above the anode. Above the control electrode, a plurality of filaments 2 (2a, 2b) for emitting electrons are provided as shown in FIG.

As shown in FIG. 1, in the fluorescent display tube of the present embodiment, a pair of first cathode supports 3a, 4a having a plurality of first filaments 2a stretched at a predetermined pitch, and a plurality of first filaments 2a are provided. A pair of second cathode supports 3b, 4b having two filaments 2b stretched at the same pitch are arranged on the anode substrate 1 by being shifted by a half pitch in a direction orthogonal to the longitudinal direction of the filaments 2 and arranged on the anode substrate 1; The arrangement pitch of No. 2 is half of the predetermined size.

The first cathode supports 3a and 4a are elongated plate-like members having external leads 5a. The pair of first cathode supports 3a and 4a are formed of a pair of elongated plate-like frames 1.
0 and 11 are connected in a frame shape. Frame 11
Are provided with a plurality of external leads 14. First
Since the cathode supports 3a and 4a penetrate the sealing portion of the envelope, they are composed of a 426 alloy (42% Ni, 6% Cr, balance Fe) having a coefficient of thermal expansion close to that of the glass sealing material. . First cathode support 3 corresponding to a diagonal position of anode substrate 1
A getter ring 7 in which an evaporable getter substance is filled is attached to each of two positions on a and 4a.

The first cathode support 3a has a first anchor 8
a is welded at a predetermined pitch. In this example, the predetermined pitch is 2 mm. The first anchor 8a is formed by punching a plate material into a predetermined shape and bending the plate material into a shape as shown in FIG. 2A in which a predetermined spring property is obtained. The first anchor 8a is formed of stainless steel so as to obtain a necessary spring property.

The other first cathode support 4a has the first
The same number of first supports 9a as the anchors 8a are welded at the same pitch as the first anchors 8a. First support 9a
Is obtained by punching a plate material into a predetermined shape, bending the plate material, and forming it into a shape as shown in FIG.

The first anchor 8a is bent inward in the longitudinal direction of the anode substrate 1, one end of the first filament 2a is fixed to the free end (tip) by welding, and the other end of the first filament 2a is fixed. Is fixed to the first support 9a by welding, and the first filament 2a is stretched with a predetermined tension. The number of the first filaments 2a in this example is seven. The filament 2 is obtained by depositing an oxide of (Ba, Sr, Ca) O as an electron emitting material around a tungsten core wire.

When the first filament 2a expands and expands, the bent first anchor 8a elastically returns outward in the longitudinal direction of the anode substrate 1. In FIG. 1, when the first filament 2a expands, the first anchor 8a returns to bend so that the free end moves to the left. While the first filament 2a remains stretched between the first anchor 8a and the first support 9a, the other end fixed to the first anchor 8a moves downward about the first support 9a.

A pair of second cathode supports 3b, 4b are arranged inside the pair of first cathode supports 3a, 4a. The second cathode supports 3b, 4b are elongated plate-shaped members having external leads 5b. Each second cathode support 3b, 4b
Are arranged at positions close to the first cathode supports 3a, 4a, respectively. The pair of second cathode supports 3b, 4b
They are connected in a frame shape by a pair of elongated plate-shaped frames 12 and 13. A plurality of external leads 15 are formed on the frame 13. The configuration of the second cathode supports 3b, 4b is substantially the same as that of the first cathode supports 3a, 4a, and the corresponding portions are denoted by the same reference numerals as those of the first cathode supports 3a, 4a, and description thereof is omitted. .

On one of the second cathode supports 3b provided near the first cathode support 3a having the first anchors 8a, the second anchors 8b of which the number is one less than the first anchors 8a are provided. It is welded at the same pitch as the anchor 8a. The material and structure of the second anchor 8b is the first anchor 8
Same as a.

On the other second cathode support 4b provided near the first cathode support 4a having the first support 9a, the second support 9b, which is one less than the first support 9a, is provided with the first support 9b. It is welded at the same pitch as the support 9a. The material and structure of the second support 9b are the first support 9
Same as a.

Six second filaments 2b are stretched between the second anchor 8b and the second support 9b. Second
The filament 2b is shorter than the first filament 2a. The first filament 2a and the second filament 2b have the same thickness. The position of the second anchor 8b in the direction orthogonal to the longitudinal direction of the filament 2 is shifted by a half pitch from the position of the first anchor 8a. The position of the second support 9b in the direction orthogonal to the longitudinal direction of the filament 2 is shifted from the position of the first support 9a by a half pitch. The second filament 2b is arranged at an intermediate position between two adjacent first filaments 2a, 2a.

A process for manufacturing a fluorescent display tube having the above-described filament extending structure will be briefly described. An anode is formed on the anode substrate 1, and a control electrode is formed thereon. As shown in FIG. 1, seven first filaments 2
a is a pair of first cathode supports 3 stretched at a pitch of 2 mm.
a, 4a and a pair of second cathode supports 3b, 4b on which six second filaments 2b are stretched at a pitch of 2 mm,
By combining the two filaments 2a and 2b at a half pitch (1 mm) in a direction orthogonal to the longitudinal direction,
The three filaments 2a and 2b are arranged in parallel at a pitch of 1 mm. In this state, the frames 10 and 11 of the first cathode supports 3a and 4a and the frames 1 and 2 of the second cathode supports 3b and 4b are arranged.
2, 13 are connected. The connected two cathode supports are arranged on the anode substrate 1, and the filament 2 is positioned with respect to an anode and a control electrode (not shown). The inner ends of the external leads 14 of the frames 10, 11 connecting the first cathode supports 3 a, 4 a are connected to a terminal (not shown) such as an anode formed on the anode substrate 1. Second cathode support 3
External leads 1 of frames 12 and 13 connecting b and 4b
5 is connected to a terminal (not shown) such as an anode formed on the anode substrate 1. A box-shaped container is sealed on the anode substrate 1 with the external leads 5, 14, and 15 interposed therebetween.
The external leads 5, 14, and 15 protrude to the outside through the sealed portion of the envelope in an airtight manner. Frames 10, 11, 1
2 and 13 are separated from the external leads 5, 14 and 15.

For example, a DC voltage is applied to the filament when used as an in-vehicle fluorescent display tube.
When a DC voltage is applied to the filament, which is a long cathode, a potential gradient occurs, and a difference occurs in the brightness of the anode along the filament. This phenomenon is called luminance gradient. In this example, the height of the arm portion of the anchor 8 set to provide a predetermined spring property is larger than the height of the support 9, so that the filament 2 is not completely parallel to the surface of the anode substrate 1. , The side of the anchor is inclined higher. Therefore, in this example, the support 9 having a small distance between the anode (or the control electrode) and the filament 2 is connected to the positive electrode of the DC power supply, and the anchor 8 having a large distance between the anode (or the control electrode) and the filament 2 is connected to the DC power supply. -Connected to the pole. In this way, the luminance gradient can be eliminated and the luminance of the light-emitting display at the anode can be made uniform.
If the distance between the filament and the anode can be reduced by changing the structure of the anchor 8, it is possible to make the anchor 8 side positive.

In this embodiment, the first anchor 8a and the second anchor 8a
The anchor 8b is commonly connected and connected to the negative pole of the DC power supply, and the first support 9a and the second support 9b are commonly connected and connected to the positive pole of the DC power supply. First filament 2a
And the second filament 2b have the same thickness (resistance per unit length) but different lengths, so that the emission of both filaments 2a and 2b is not the same, but the two filaments 2a and 2b are alternately , The display quality is not adversely affected.

Since the first filament 2a and the second filament 2b have the same thickness (resistance per unit length) and different lengths, a relatively high voltage is applied to the longer first filament 2a, If a relatively low voltage is applied to the second filament 2b, the emission becomes the same for both filaments 2a and 2b, but the length of the filament 2b does not substantially change, and the filament 2b can be driven at the same voltage. It is.

According to the fluorescent display tube of this embodiment, the pitch (interval) of the filament can be made smaller than that of the conventional fluorescent display tube without changing the structure or function of the anchor and the support. That is, conventionally, the pitch was required to be at least 1.5 mm or more (usually 2 mm or more) due to the problem of anchor design such as elasticity and strength. Pitch was realized. For this reason, a larger number of filaments can be stretched than in the conventional case in an envelope of the same size, and when the anode and the control electrode are driven at a low voltage of about 13.5 V, the value is 1.6 times the conventional value. Emission luminance of a certain anode 7000
cd / m ² was obtained.

According to the fluorescent display tube of the present embodiment, the first and second
In the longitudinal direction of the filaments 2a, 2b, the first anchor 8a and the second anchor 8b are on the same side, and the first support 9a and the second support 9b are on the same side.
When the first and second filaments 2a and 2b thermally expand and the deflection of the first and second anchors 8a and 8b returns, and the positions of the first and second filaments 2a and 2b change, the adjacent first and second filaments 2a and 2b change. There is no possibility that the filaments 2a and 2b come into contact with each other. That is, in FIG. 1, the thermally expanded first and second filaments 2a and 2b both move downward about the first and second supports 9a and 9b.

A second example of the embodiment of the present invention will be described with reference to FIG. The structure of the fluorescent display tube is the same as that of the first example. As shown in FIG. 3, in this example, the first filament 2
a and the second filament 2b can be driven separately. That is, the first anchor 8a and the first support 9a
Is connected to a DC power supply 17 via a switch 16, and the second anchor 8b and the second support 9b are connected to a DC power supply 19 via a switch 18. The polarity of the connection is the same as in the first example. The DC power supplies 17 and 19 may be common. In this case, both the filaments 2a and 2b are turned on at the same time, or one of the filaments is turned on (ie, only the first filament 2a is turned on or only the second filament 2b is turned on). (Or three) can be selected. For example, when used in a vehicle, both filaments 2a and 2b are turned on in the daytime to secure a sufficient light emission brightness against strong intense external light, and only one of the filaments is turned on at night to turn on the anode. Dim the display.

A third embodiment of the present invention will be described with reference to FIG. Parts substantially the same as those in the first example in terms of function are denoted by the same reference numerals as those in FIG. 1 and description thereof is omitted. In this example, the second cathode supports 3b, 4b, on which the second filaments 2b are stretched, are arranged at positions shifted to the right in the drawing with respect to the first cathode supports 3, 4a, on which the first filaments 2a are stretched. ing. That is, the second anchor 8b is located between the first anchor 8a and the first support 9a and at a position close to the first anchor 8a. The second support 9b is located outside the first support 9a and close to the first support 9a. Other configurations are substantially the same as those of the first example. With the above-described configuration, the length of the filament is the same for the first filament and the second filament, so that filaments having the same diameter can be used, and an effect that both can be driven at the same voltage can be obtained.

A fourth example of the embodiment of the present invention will be described. This example has the same configuration as the first example except that the weight per unit length of the first and second filaments 2a and 2b is different. That is, the weight of the long first filament 2a per unit length was made larger than the weight of the short second filament 2b per unit length. That is, the long first filament 2a is thickened, and the short second filament 2b
Was thinned. Then, the first cathode supports 3a, 4a and the second
If the cathode supports 3b and 4b are connected in common and driven by DC, the same emission can be obtained by the same DC power supply despite the different lengths of the two filaments 2a and 2b.

[0034]

According to the present invention, the two filaments stretched between the anchor and the support are combined in the same direction while being shifted in the juxtaposed direction, so that the pitch of the filaments can be made shorter than in the prior art, and sufficient emission can be achieved. And a high emission luminance can be achieved. Even when the filaments thermally expand during aging or use, adjacent filaments do not come into contact with each other.

[Brief description of the drawings]

FIG. 1 is a plan view showing a filament extending structure in a first example of an embodiment of the present invention.

2A is a perspective view of an anchor, and FIG. 2B is a perspective view of a support.

FIG. 3 is a plan view showing a filament extending structure in a second example of the embodiment of the present invention.

FIG. 4 is a plan view showing a filament extending structure in a third example of the embodiment of the present invention.

FIG. 5 is a plan view showing a filament extending structure in a conventional fluorescent display tube.

[Explanation of symbols]

2a 1st filament as a 1st filamentary cathode 2b 2nd filament as a 2nd filamentary cathode 3a, 4a 1st cathode support 3b, 4b 2nd cathode support 8a 1st anchor 8b 2nd anchor 9a 1st support 9b Second support

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[Procedure amendment]

[Submission date] September 3, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0028

[Correction method] Change

[Correction contents]

Further, an embodiment in which the same emission is obtained by changing the thickness (resistance per unit length) of the first filament 2a and the second filament 2b is also possible. That is, by using a relatively thick filament for the longer first filament 2a and a relatively thin filament for the shorter second filament 2b, the emission is the same for both filaments 2a and 2b, and the same It is also possible to drive with a voltage. By changing the thickness of the filament in this manner, there is an effect that the filament can be driven by the same power supply.

Claims (6)

[Claims] 1. A first cathode support having a plurality of first anchors and a plurality of first supports arranged in pairs, and substantially between the first anchors and the first supports arranged in pairs. A plurality of first filamentary cathodes stretched at a predetermined pitch so as to be parallel to each other, a plurality of second anchors arranged at positions close to the respective first anchors, and the respective first supports. A second cathode support in which a plurality of second supports arranged in close proximity to each other are arranged in pairs; substantially parallel to the first filamentary cathode, substantially parallel to the first filamentary cathode; At the same pitch,
And a plurality of second filamentary cathodes stretched between the second anchor and the second support arranged in a pair and in close proximity to the respective first filamentary cathodes. 2. The first filamentary cathode and the second filamentary cathode.
A DC voltage is applied to the filament cathode.
The fluorescent display tube as described. 3. The method according to claim 2, wherein the second anchor and the second support are inside the first anchor and the first support, and the second filamentary cathode is shorter than the first filamentary cathode. Fluorescent display tube. 4. The fluorescent display tube according to claim 2, wherein the second anchor is inside the first anchor and the first support, and the second support is outside the first support. 5. The first filament cathode and the second filament cathode.
The DC voltage applied to the filament cathode is substantially the same, and the weight per unit length of the filament cathode is greater in the first filament cathode than in the second filament cathode. Fluorescent display tube. 6. A DC voltage applied to the first filament cathode and a DC voltage applied to the second filament cathode are provided by two DC power circuits independent of each other, and each DC power circuit is opened and closed. The fluorescent display tube according to claim 2, which is capable of being used.