JP3215379B2 - Fluorescent display tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a fluorescent display tube having a structure in which a cathode support on which a filamentary cathode is stretched projects outside through a sealing portion of an envelope. It is.

[0002]

2. Description of the Related Art A fluorescent display tube has a flat box-shaped envelope in which various electrodes and the like are housed. As shown in FIG. 2, a general envelope 50 is configured by sealing a box-shaped container portion 52 having an open lower surface on the upper surface of a substrate 51. An anode (not shown) serving as a light-emitting display unit is formed on the upper surface of the substrate 51 in the envelope 50, a control electrode (not shown) is provided above the anode, and an electron source is provided above the control electrode. A filament cathode 53 is stretched. The filament cathode 53 is stretched between a pair of cathode supports 54 arranged at both ends of the envelope 50. Each cathode support 5
4 is a frame portion 55 that hermetically penetrates the sealed portion of the envelope 50, and a support portion 56 fixed to the frame portion 55.
And One of the support portions 56 of the pair of cathode supports 54 is a support for fixing one end of the filament cathode 53, and the other support portion 56 is an anchor for fixing and pulling the other end. The cathode support 54 in FIG. 2 is the side having the anchor.

[0003]

In the structure described above, the sealing portion of the envelope 50 has a shape of the lower end surface of the container portion 52 or a frame shape along the outer peripheral edge of the substrate 51. The frame 55 of the cathode support 54 supporting the filament cathode 53 is
Although it is fixed at the sealing portion, it is not adhesively fixed to the substrate inside the envelope 50. That is, the envelope 5
0, the cathode support 54 excluding the sealing portion
Is in contact with the upper surface of the substrate 51 except for the sealing portion or with a small gap, but is not fixed.

When the fluorescent display tube is driven, a pulse signal of a digit signal (grid scan) is sequentially applied to each grid in order to perform display, and each anode is synchronized with each digit signal to each anode. An ON (positive) or OFF (negative) pulse signal is selectively applied according to each timing. At this time, the frame 55 vibrates due to the influence of the electric field by the pulse signal from the wiring, and abnormal noise is generated.

[0005] The applicant of the present invention has proposed a fluorescent display tube having the above-described structure improved in Japanese Patent Application No. 9-37780 for the purpose of preventing the generation of the abnormal noise.

Referring to FIG. 3, the present applicant has filed Japanese Patent Application No. 9-3.
The fluorescent display tube proposed in the publication No. 7780 will be described. The envelope 61 of the fluorescent display tube is configured by sealing a box-shaped container 63 having an open lower surface on the upper surface of a substrate 62. For sealing, a sealing material 64 mainly composed of low melting point glass is used.
Is used. The substrate 62 is made of a glass plate, and the container portion 63 is also made by assembling a plurality of glass plates with a sealing material.

An anode (not shown) serving as a light emitting display section is formed on the upper surface of the substrate 62 in the envelope 61, and a control electrode (not shown) is provided above the anode, and further above the anode. A filament cathode 65 as an electron source is stretched.

The filament cathode 65 is stretched between a pair of cathode supports 66, 66 arranged at both ends of the envelope 61. Each cathode support 66 has a frame 67 that hermetically penetrates the sealed portion of the envelope 61, and a support portion 68 fixed to the frame 67. A pair of cathode supports 6
6 and 66, one of the support portions 68 is
5 is a support for fixing one end of the support member 5, and the other support portion 68
Is an anchor for fixing and pulling the other end.

The frame 67 penetrates through the sealed portion of the envelope 61, so that 42% of Ni, 6% of Cr, and F
The support portion 68, which is made of an alloy having a coefficient of thermal expansion close to that of glass, such as 426 alloy made of e, and requires spring properties like an anchor, is made of a material such as stainless steel.

The entire lower surface of the frame 67 is
2 is fixed to the upper surface by a sealing material 64. In order to fix the frame 67 to the substrate 62 in this way, as shown in FIG.
A sealing paste 64 is applied to a predetermined position on the upper surface of the substrate 62 with which the substrate 7 contacts. At the time of assembling, the frame 67 to which the support portion 68 is welded is placed thereon, and the container portion 6
3 is put on, assembled, heated and sealed.

In the above-described structure, the sealing portion of the envelope 61 has a frame shape along the shape of the lower end surface of the container portion 63 or the outer peripheral edge of the substrate 62. The frame 67 of the cathode support 66 that supports the filamentary cathode 65 is fixed at the sealing portion, and is entirely fixed on the upper surface of the substrate 62 inside the envelope 61. That is, inside the envelope 61, the lower surface of the cathode support 66 is entirely fixed to the upper surface of the substrate 62.

Since the frame 67 is fixed to the substrate 62 as described above, the filament cathode 6 is used for use.
No abnormal noise is generated between the cathode support 66 and the substrate 62 even when an alternating current is applied to 5. Further, since the cathode support 66 does not vibrate, the height of the cathode support 66 on the substrate 62 is stabilized.

In the above-described example, the entire lower surface of the frame 67 is fixed to the upper surface of the substrate 62, but at least one portion of the lower surface of the frame 67 other than the sealing portion of the envelope 61 is The frame 67
Accordingly, a corresponding effect of preventing vibrations can be obtained.

The entire lower surface of the frame 67 of the cathode support is fixed to the upper surface of the glass substrate 62 with a sealing material 64. The frame 67 has a coefficient of thermal expansion close to that of glass.
Although it is made of an alloy such as alloy No. 6, there is a slight difference in the coefficient of thermal expansion from the sealing material 64 mainly composed of frit glass. For this reason, stress is generated between the frame 67 and the sealing material 64 due to heat generated during use, and cracks are generated in the frit glass in which the sealing material is solidified, and fine glass fragments may be generated in the envelope. is there. Such a foreign substance is harmful to the fluorescent display tube and its display, and thus another solution is required to prevent the above-mentioned abnormal noise.

The present inventor has further studied the cause of the above-mentioned abnormal noise in order to solve the problem. As a result, the present inventor considered that the above-mentioned abnormal
Attention was paid to the distance from the frame placed on the substrate.
In the conventional fluorescent display tube shown in FIG. 4, as a cause of the above-mentioned abnormal sound, the frame 75 and the wiring 73 on the substrate 72 are used.
Is not considered at all, and the frame 75 and the wiring 73 are overlapped or almost in contact with each other as shown in the figure. When a signal is applied to a wiring in such a state that the wiring and the frame are very close to each other, it is conceivable that vibration is generated in the frame due to the influence of an electric field generated by the signal.

Therefore, the present inventor conducted an experiment using the apparatus shown in FIG. 5 in order to confirm the above-mentioned hypothesis. 10
The output of the pulse oscillator 80 having a frequency of 0 Hz to 1 kHz is amplified by the amplifier 81, and this output is given to the anode or grid wiring 73. The negative side is the cathode frame 75.
Connected to. As a fluorescent display tube serving as a sample, a study was conducted using various samples, from those having no space between the frame 75 and the wiring 73 to those that do not overlap and those that touch or overlap. That is, FIG.
The wiring 73 and the frame 75 are separated as if two types were displayed at the same time (distance-Xmm)
And various distances ± X mm for the case where the wiring 73 and the frame 75 overlap (the overlapping distance + X mm).
A sample having the following was prepared and tested.

As a result of forcibly applying a pulse of the above-mentioned frequency to the fluorescent display tubes of these samples and measuring the resonance,
It has been found that a lot of abnormal noise is generated when the frame 75 and the wiring 73 overlap, touch, or are very close to each other. A pulse signal of the frequency
3, the electric field around the wiring 73 changes. When the wiring 73 and the frame 75 are close to each other, it is considered that the influence of the change in the electric field causes the frame 75 to resonate.

In view of the above experimental results, the main cause of the abnormal noise generation in the frame is the problem of the distance between the wiring to which the pulse signal is applied and the frame, and therefore, when the frame and the wiring are close to each other. The present inventor has considered that abnormal noise is generated when a pulse signal of a certain frequency is applied to the anode or the control electrode to drive the fluorescent display tube.

According to the present invention, in a fluorescent display tube having a structure in which a cathode support of a filament cathode is arranged on a substrate of an envelope, when a pulse signal is applied to wiring on the substrate,
It is intended to prevent the cathode support from vibrating and generating abnormal noise.

[0020]

According to a first aspect of the present invention, there is provided a fluorescent display tube provided with a flat box-shaped envelope in which a substrate (2) and a container are sealed , and disposed on the substrate. Wiring (3),
An insulating layer (9) provided on the wiring, and the insulating layer
Anode and a control electrode provided on the
A pole, a cathode support (frame 5) disposed on the insulating layer and penetrating the sealed portion of the envelope, and extended to the cathode support (frame 5) inside the envelope. The cathode support (frame 5) in a direction perpendicular to the substrate.
From the point of view that it was placed on the insulating layer in the area (6) where there is no wiring.
And features.

According to a second aspect of the present invention, in the fluorescent display tube according to the first aspect, when the fluorescent display tube is driven, the frequency of the anode and the control electrode ranges from 100 Hz to 100 Hz.
It is characterized in that a pulse signal of 1 kHz is applied.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a countermeasure against the above-mentioned abnormal noise and vibration, the structure of the wiring on the substrate is improved to provide portions without wiring on both sides of the substrate, and this is provided on the mounting area of the cathode support. The effective condition is that the cathode support and the wiring do not overlap or come into contact with each other and that the cathode support is sufficiently separated from the wiring so that harmful resonance does not occur.

An example of an embodiment of the present invention will be described with reference to FIG. The basic structure of the fluorescent display tube of this embodiment is substantially the same as the fluorescent display tube described in the section of the prior art and the fluorescent display tube described in Japanese Patent Application No. 9-37780 filed by the present applicant. is there.

That is, the envelope of the fluorescent display tube of the present embodiment is configured by sealing a box-shaped container having an open lower surface on the upper surface of the substrate 2. For sealing, a sealing material mainly composed of low-melting glass is used. Note that the substrate 2 is made of a glass plate, and the container portion is also made by assembling a plurality of glass plates with a sealing material.

An anode wiring 3 is provided on the upper surface of the substrate 2 in the envelope. An insulating layer 9 is provided on the wiring 3. On the insulating layer 9, an anode (not shown) serving as a light emitting display section is formed. The anode and the wiring 3 are connected via a through hole formed in the insulating layer 9. The wiring 3 of the anode is connected to an internal terminal 4 formed on the edge of the substrate 2. A control electrode (not shown) is also provided on the insulating layer 9.

Above the substrate 2, a filament cathode (not shown) serving as an electron source is extended. The filament cathode is stretched between a pair of cathode supports arranged at both ends of the envelope. Each cathode support comprises a frame 5 (pressing plate) which hermetically penetrates the sealed portion of the envelope, and a frame 5
And a support portion fixed to the support portion. One of the support portions of the pair of cathode supports is a support for fixing one end of the filament cathode, and the other support portion is an anchor for fixing and pulling the other end.

The frame 5 is made of an alloy having a thermal expansion coefficient close to that of glass, such as a 426 alloy composed of 42% of Ni, 6% of Cr and the balance of Fe. The supporting portion that requires the spring property is made of a material such as stainless steel.

As shown in FIG. 1, in this example, the wiring 3 on the substrate 2 is arranged so that no wiring is provided in the regions 6 and 6 at both ends of the substrate 2, and the region 6 without the wiring 3 is provided. The frame 5 was provided on the insulating layer 9. That is, when viewed from the direction perpendicular to the substrate 2, there is no wiring 3 below the frame 5, and the frame 5 and the wiring 3 are not in contact with each other.

[0029]

According to this embodiment, the cathode support provided at both ends of the substrate and the wiring on the substrate are sufficiently separated from each other, so that the cathode support can be resonated by a pulse signal applied to the wiring. Is prevented, and generation of abnormal noise between the cathode support and the substrate can be prevented. Further, if the vibration of the cathode support is prevented, the height of the cathode on the substrate is stabilized, so that the light emission luminance of the display section is stabilized.

[Brief description of the drawings]

FIG. 1 is a plan view of both ends of a substrate according to an example of an embodiment of the present invention.

FIG. 2A is a view taken along line aa of FIG. 2B, and is a plan view of a substrate in an example of a conventional fluorescent display tube;
(B) is a sectional view of an example of a conventional fluorescent display tube.

FIG. 3 (a) is a view taken along the line aa of FIG. 3 (b), and is a plan view of the substrate in the invention proposed by the present inventor in Japanese Patent Application No. 9-37780, and FIG. It is sectional drawing of this invention.

FIG. 4 is a plan view of both ends of a substrate in a conventional fluorescent display tube.

FIG. 5 is a schematic diagram of an experimental device proposed by the present inventor to study the cause of a conventional problem.

[Explanation of symbols]

 2 Substrate 3 Wiring 5 Frame (holding plate) 6 Frame mounting area without wiring (area)

Claims (2)

(57) [Claims] 1. A flat box-shaped envelope formed by sealing a substrate and a container, wiring provided on the substrate, and wiring of the wiring.
An insulating layer provided on the insulating layer,
An anode and a control electrode connected to the wiring, and the insulating layer
A fluorescent display tube having a cathode support disposed on the base and penetrating the sealing portion of the envelope, and a filament cathode stretched on the cathode support inside the envelope; Wiring the cathode support as viewed from the direction perpendicular to the substrate
A fluorescent display tube, which is disposed on an insulating layer in a region where there is no void. 2. The fluorescent display tube according to claim 1, wherein a pulse signal having a frequency of 100 Hz to 1 kHz is applied to the anode and the control electrode when the fluorescent display tube is driven.