JP2002050311A - Fluorescent display tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a quiet fluorescent display tube without producing abnormal noise during light-emitting drive. SOLUTION: The fluorescent display tube has an envelope consisting of an insulating board 1 and a container 11 sealed on a top face side of the board, and inside the envelope are an anode 2 and a cathode 8 equipped with phosphor. A wiring conductor 3 formed on the top face of the board is covered with an insulating layer 4. On a conductive layer 20 formed partially on the insulating layer 4, an electrode member 15 fitted with a stretch-set member 9 of the cathode 8. Since the conductive layer 20 does not move even when the wiring conductor 3 and the conductive layer 20 make up a capacitor to endow the conductive layer 20 with electrostatic force, the electrode member will not vibrate.

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 which has solved the problem of abnormal noise generated during light emission driving.

FIG. 4 is an exploded perspective view illustrating the configuration of a conventional fluorescent display tube. A wiring conductor 3 connected to the anode 2 is formed on the upper surface of the insulating substrate 1. An insulating layer 4 is provided on the upper surface of the substrate 1 so as to cover at least a part of the wiring conductor 3. An anode conductor 5 is provided on the insulating layer 4. The anode conductor 5 and the wiring conductor 3 are connected and conductive via a conductive material in a through hole formed in the insulating layer 4. Phosphor 6 is provided on anode conductor 5 to constitute anode 2. Slender rectangular substrate 1
Is provided with an elongated plate-shaped electrode member 7. The electrode member 7 is arranged on and in contact with the insulating layer 4. An extension member 9 such as an anchor support for extending the cathode 8 is attached on the electrode member 7. A part of the substrate 1 on which the insulating layer 4 is not formed has I
C10 is provided, and the wiring conductor 3 is connected. A box-shaped container portion 11 having an open lower surface is sealed on the upper surface side of the substrate 1 to form an envelope containing the electrodes therein. The inside of the envelope is evacuated to a high vacuum state.

[0003]

When the fluorescent display tube emits light and is driven, an unpleasant noise may occur. In particular,
This is a concern when the surroundings are quiet, and an important problem when used as a display unit of an audio product.

SUMMARY OF THE INVENTION An object of the present invention is to investigate the cause of abnormal noise generation in a fluorescent display tube, find a solution to the problem, and realize a quiet fluorescent display tube.

[0005]

According to a first aspect of the present invention, there is provided a fluorescent display tube comprising an envelope comprising an insulating substrate and a container sealed on the upper surface of the substrate. A fluorescent display tube provided with the wiring conductor (3) formed on the upper surface of the substrate, an insulating layer (4) provided on the upper surface of the substrate so as to cover the wiring conductor, and formed on the upper surface of the insulating layer. A conductive layer (20), and an electrode member (15) provided on the conductive layer.

According to a second aspect of the present invention, there is provided a fluorescent display tube provided with an envelope comprising an insulating substrate (1) and a container (11) sealed on the upper surface side of the substrate. ,
A wiring conductor (3) formed on the upper surface of the substrate, an insulating layer (4) provided on the upper surface of the substrate so as to cover the wiring conductor, and a conductive layer (2) formed on the upper surface of the insulating layer
0) and a conductive electrode member (15) which is provided on the conductive layer and is led out of the envelope by being sandwiched between the portions where the container and the substrate are sealed. Have.

According to a third aspect of the present invention, there is provided a fluorescent display tube having an envelope comprising an insulating substrate (1) and a container (11) sealed on the upper surface side of the substrate. In a fluorescent display tube provided with an anode (2) having a phosphor (6) and a cathode (8) for emitting electrons, a wiring conductor formed on the upper surface of the substrate and connected to the anode (3)
And an insulating layer (4) provided on at least a part of an upper surface of the substrate so as to cover at least a part of the wiring conductor.
And a conductive layer (2) formed on a part of the upper surface of the insulating layer.
0), and a conductive layer provided on the conductive layer to support the cathode, and is led out of the envelope by being sandwiched between portions where the container and the substrate are sealed. It has an electrode member (15) and a drive source for applying a fluctuating voltage between the anode and the cathode.

According to a fourth aspect of the present invention, there is provided the fluorescent display tube according to the third aspect, wherein the wiring conductor (3) is provided on a portion of the substrate (1) where the insulating layer (4) is not formed. An electronic component (IC10) to which is connected is provided, and one ends of the plurality of wiring conductors are arranged substantially parallel to each other along a predetermined direction in order to be connected to the electronic component. The electrode member (15) has a rectangular shape in a plan view, and is provided so as to cover the one end so that a direction intersecting the predetermined direction of the wiring conductor is a longitudinal direction.

According to a fifth aspect of the present invention, there is provided the fluorescent display tube according to the third aspect, wherein the conductive layer (20) has the same potential as the electrode member (15).

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The inventor of the present invention will explain the reason why abnormal noise is generated during driving in a conventional fluorescent display tube. The present inventor has found that abnormal noise is generated by vibration of a cathode electrode member. As a result of intensive studies on the causes, the following phenomena were recognized. That is, as shown in FIG. 3, when the fluorescent display tube is driven, a capacitor is formed by the electrode member 7 and the wiring conductor 3,
It is considered that the ON and OFF signals alternately applied to the anode 2 and the like at the time of driving cause the electrode member 7 to be repeatedly bent by the electrostatic force. Then, it is considered that this action caused the electrode member 7 to vibrate, and the vibration energy was converted to sound energy, thereby generating abnormal noise.

The present inventor has devised, for the first time, a means for solving this problem based on elucidation of the cause of the abnormal noise. That is, in the past, it was naturally considered that the electrode member 7 supporting the cathode 8 was directly provided on the insulating layer 4. However, in the embodiment of the present invention, a conductive layer was provided on the insulating layer, The electrode member was disposed thereon. Then, as a more preferable configuration, the conductive layer was set to the same potential as the electrode member. With this configuration, the electrode member does not cause practically harmful vibration.

An embodiment of the present invention having such an electrode member will be described with reference to FIGS. FIG. 1 is an exploded perspective view showing the configuration of the fluorescent display tube of this example, and FIG.
It is sectional drawing in the cutting line in a middle. The insulating substrate 1 is a long and narrow rectangular plate material, and a wiring conductor 3 connected to the anode 2 is formed on the upper surface thereof. An insulating layer 4 is provided on the upper surface of the substrate 1 so as to cover at least a part of the wiring conductor 3. An anode conductor 5 is provided on the insulating layer 4. The anode conductor 5 and the wiring conductor 3 are connected and conductive via a conductive material in a through hole formed in the insulating layer 4. Phosphor 6 is provided on anode conductor 5 to constitute anode 2.

As shown in FIGS. 1 and 2, a conductive layer 20 is partially formed on the insulating layer 4 at the end of the substrate 1. The conductive layer 20 of this example is a graphite layer, and its thickness is about 20 μm. The conductive layer 20 can be made by printing and firing graphite paste. The conductive layer 20 is electrically connected to a dedicated wiring 21 formed on the substrate 1 via a conductive material filled in a through hole formed in the insulating layer 4. The wiring 21 is routed on the substrate 1 and connected to the lead 22. The lead 22 is airtightly penetrated through the portion where the container 11 and the substrate 1 are sealed, and is led out of the envelope.

The conductive layer 20 of the present embodiment is formed of an electrode member 1 described later.
5 and the wiring conductor 3 are provided at portions facing each other with the insulating layer 4 interposed therebetween. That is, they are provided in an arrangement, area, and shape that shield the electrode member 15 and the wiring conductor 3 from each other.

An elongated plate-like electrode member 15 is provided at an end of the elongated rectangular substrate 1 in an arrangement orthogonal to the longitudinal direction of the substrate 1. Although the elongated plate-shaped electrode member 15 is on the conductive layer 20, the electrode member 15 may or may not be in contact with the conductive layer 20. That is, if the plate-like electrode member 15 is placed on the flat conductive layer 20 and fixed at the sealed portion of the envelope, the electrode member 15 is considered to be in contact with the conductive layer 20; There is no problem even if it is in a raised state.

Both end portions of the electrode member 15 are fixed by being sandwiched between portions where the container portion 11 and the substrate 1 are sealed, and one end portion of the electrode member 15 is led out of the envelope and connected to the lead portion 16. Have been. An extension member 9 such as an anchor support for extending the cathode 8 is attached on the center of the electrode member 15.

In this embodiment, the leads 22 of the conductive layer 20
And the lead portion 16 of the electrode member 15 projecting to the outside,
The same potential is applied. Although not shown, a control electrode is provided between the cathode 8 and the anode 2.

At the longitudinal end of the substrate 1, there is a portion where the insulating layer 4 is not formed, and an IC 10 is provided here. At the end of the substrate 1, the plurality of wiring conductors 3 are densely arranged in parallel with each other along the longitudinal direction of the substrate 1 and are connected to the IC 10.

A box-shaped container portion 11 having an open lower surface is sealed on the upper surface side of the substrate 1 to constitute an envelope containing the electrodes therein. The inside of the envelope is evacuated to a high vacuum state.

In the above configuration, an AC voltage or a pulse voltage is applied between the wiring conductor 3 and the electrode member 15 so that the anode 2
Is displayed, and the abnormal noise due to the vibration of the electrode member 15 is measured in the anechoic chamber. In this example, measurement was performed on five test specimens having the same specifications. For comparison, an abnormal sound was measured on a conventional fluorescent display tube under the same conditions as in this example. The measurement was also performed on five specimens having the same specifications in the conventional example. To the fluorescent display tubes of this example and the comparative example, a driving voltage of 30 V and a duty ratio of 1/16 was applied to the anode 2 and the control electrode.

According to the fluorescent display tube of the present embodiment, the abnormal noise generated was a value of 30 dB or less in all cases. This is a boundary level of whether the sound can be heard at a distance of 20 cm from a normal person's ear, and there is almost no problem in consideration of a normal use state as a display device. If it is 35 dB or more, it is unpleasant and cannot be used as an audio display device. Here, the noise of the conventional fluorescent display tube is 6
The range is from 2.3 dB to 69.6 dB, and the average is 6 dB.
Since it is 6.6 dB, it can be said that the value reaches a level that is not practically acceptable.

In this example, the conductive layer 20 and the wiring conductor 3 face each other with the insulating layer 4 interposed therebetween, which is considered to constitute a capacitor. However, since the conductive layer 20 is in close contact with the insulating layer 4, static electricity is generated. Receives power but does not move. Therefore, even if the electrode member 15 is in contact with the conductive layer 20, it does not vibrate.

As described above, according to the fluorescent display tube of the present embodiment,
A conductive layer 20 having the same potential as that of the cathode electrode member 15 is provided on the insulating layer 4 covering the wiring conductor 3.
5, the electrode member 15 does not vibrate due to electrostatic force.

In particular, when the present embodiment is a fluorescent display tube for graphic display, the number of pixels to be driven and controlled is large, and therefore the number of wiring conductors is also large. When a control electronic element (IC 10 in this example) is provided on the substrate 1, the wiring conductor must be routed on the substrate to concentrate on the position where the IC 10 is provided. Usually I
Since C is arranged at the end of the substrate remote from the display unit, the wiring conductors are collected at that portion. This portion also corresponds to the end of the cathode of the fluorescent display tube, and the electrode member supporting the cathode is also located here. Therefore, in such a fluorescent display tube for graphic display, etc., it can be said that the conditions under which the vibration of the electrode member is likely to occur are prepared. However, such a disadvantage can be avoided by employing the configuration of this example.

In the example described above, the conductive layer 20 is a graphite layer made of a graphite paste, but may be made of a silver paste. In addition, as long as a conductive film such as a deposited ITO, a deposited metal, or a printed ITO can be formed, the material and the manufacturing method are not limited.

In the example described above, since the conductive layer 20 is electrically pulled out of the envelope by the lead 22 to have the same potential as the cathode 8, the electrode member 15 does not always contact the conductive layer 20. It was good. However, if the electrode member 15 is placed on the conductive layer 20 and electrical contact is secured, the lead 22 for the conductive layer 20 is not necessarily required.

In the above-described example, the electrode member which supports the cathode support has been exemplified as a member in which vibration has conventionally been a problem. However, other conductive members opposed to each other with a wiring conductor and an insulating layer interposed therebetween are exemplified. The present invention can be similarly applied to members.

In the example described above, an AC voltage (or a pulse wave) is applied between the wiring conductor 3 and the electrode member 15, but the AC voltage is the term in the broadest sense, and the sine wave in a narrow sense. It includes not only the alternating voltage but also the fluctuating voltage of any time-varying waveform such as a square wave, a sawtooth wave, and a pulse wave, which may cause the above-described conventional problems.

[0029]

As described above, according to the fluorescent display tube of the present invention, in a fluorescent display tube in which an insulating layer is provided so as to cover a wiring conductor on the upper surface of a substrate, an upper surface of the insulating layer above the wiring conductor is provided. Since the conductive layer was provided and the electrode member was provided thereon,
There is no possibility that the electrode member generates harmful vibration.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a fluorescent display tube according to an embodiment of the present invention.

FIG. 2 is a sectional view of the fluorescent display tube taken along a section line in FIG.

FIG. 3 is a diagram schematically showing a mechanism of vibration of an electrode member in the fluorescent display tube.

FIG. 4 is an exploded perspective view of a conventional fluorescent display tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 3 ... Wiring conductor 4 ... Insulating layer 10 ... IC which is an electronic element 11 ... Container part 15 ... Electrode member 20 ... Conductive layer

Continued on the front page (72) Inventor Kazuhiko Tojo 629 Oshiba, Mobara-shi, Chiba Futaba Electronics Industry Co., Ltd. (72) Inventor Yoshiaki Washio 629 Oshiba, Mobara-shi, Chiba Futaba Electronics Industry Co., Ltd. (72) Inventor Toi Shinichiro 629 Oshiba, Mobara-shi, Chiba Futaba Electronics Co., Ltd. F-term (reference) 5C036 EE19 EG02 EG11 EG48 EH04

Claims (5)

[Claims] 1. A fluorescent display tube provided with an envelope comprising an insulating substrate and a container sealed on the upper surface side of the substrate, wherein: a wiring conductor formed on the upper surface of the substrate; A fluorescent display tube comprising: an insulating layer provided on the upper surface of the substrate so as to cover the conductive layer; a conductive layer formed on the upper surface of the insulating layer; and an electrode member provided on the conductive layer. 2. A fluorescent display tube provided with an envelope comprising an insulating substrate and a container sealed on the upper surface side of the substrate, wherein: a wiring conductor formed on the upper surface of the substrate; An insulating layer provided on the upper surface of the substrate covering the insulating layer; a conductive layer formed on the upper surface of the insulating layer; and a portion provided on the conductive layer and sealing the container and the substrate. And a conductive electrode member led out of the envelope by being sandwiched between them. 3. An envelope comprising an insulating substrate and a container sealed on the upper surface side of the substrate, wherein an anode provided with a phosphor and a cathode emitting electrons are provided in the envelope. A wiring conductor formed on the upper surface of the substrate and connected to the anode; and an insulating layer provided on at least a part of the upper surface of the substrate so as to cover at least a part of the wiring conductor. A conductive layer formed on a part of the upper surface of the insulating layer, provided on the conductive layer to support the cathode,
A conductive electrode member that is led out of the envelope while being sandwiched by a portion where the container and the substrate are sealed, and a drive source that applies a fluctuating voltage between the anode and the cathode. A fluorescent display tube having: 4. An electronic component to which the wiring conductor is connected is provided on a portion of the substrate where the insulating layer is not formed, and one end of the plurality of wiring conductors to be connected to the electronic component. The portions are arranged substantially parallel to each other along a predetermined direction, the electrode member is rectangular in plan view, and the longitudinal direction is a direction intersecting the predetermined direction of the wiring conductor. 4. The fluorescent display tube according to claim 3, wherein the fluorescent display tube is disposed so as to cover one end. 5. The fluorescent display tube according to claim 3, wherein said conductive layer has the same potential as said electrode member.