JPS6236339B2 - - Google Patents

Description

Detailed Description of the Invention The present invention aims at increasing display brightness and luminous efficiency by selecting the pore diameter of the discharge cell and the diameter of the through hole of the cathode electrode, as well as selecting the distance between the front plate and the cathode electrode. The present invention relates to a DC type gas discharge display device.

First, an example of a conventional DC discharge type gas discharge display device will be described with reference to a cross-sectional view of a main part in FIG. 1 is a front plate glass, 2 is a back plate glass, and a cathode electrode 3 is placed between them.
and an anode electrode 4 are disposed with spacers 5, 6 and an insulating layer 7 interposed therebetween. These front plate 1 and back plate 2 constitute an outer casing, and the periphery of the casing is vacuum-sealed to form a vacuum container, and rare gases such as neon, argon, xenon, and krypton are contained inside. A gas that mainly contributes to the discharge is sealed. The insulating layer 7 may be formed by thick film printing of powdered glass or thin plate glass, or may be formed integrally with the front plate by drilling a negative glow overflow space 11 in the front plate glass 1. Note that 10 is a discharge cell, and 11 is a space between the front plate glass 1 and the cathode electrode 3 through which the negative glow 9 overflows. The thickness D of the insulating layer 7 is equal to 4 to 4 of the equilibrium collision distance (electron mean free path) λ _e between the electrons in the plasma caused by the discharge and the gas molecules.
It is selected to be about 25 times larger. And cathode electrode 3
By applying a DC voltage contributing to a predetermined discharge between the anode electrode 4 and the anode electrode 4, a desired discharge display is performed.

By the way, during the discharge operation of this conventional DC discharge type gas discharge display device, a negative glow 9 is distributed from the side surface of the edge of the through hole 8 of the cathode electrode 3 to the lower surface as shown in the figure. For example, when the thickness of the insulating layer 7 is selected to be 6λ _e , the discharge display state of the gas discharge display device is negative glow 9 as shown in FIG.
is distributed from the central part of the side surface of the edge of the through hole 8 to the lower surface, as shown in FIG. 2 when viewed from the top surface of the front plate glass 1, and only around the edge of the through hole 8 of the cathode electrode 3 distributed, but not in the central part. In addition, when the thickness of the insulating layer 7 is selected to be 20λ _e , the negative glow 9 does not reach the top surface of the cathode electrode 3 as shown in FIG. When visually observed from the top surface of the front plate glass 1, as shown in FIG.

That is, when the thickness of the insulating layer 7 is in the range of 6λ _e to 20λ _e , the negative glow 9 does not go around to the front plate glass 1 side, which is the upper surface of the cathode electrode 3, and even if the discharge current is increased, the negative glow 9 is forced. Even if an attempt is made to expand and distribute the negative glow 9 toward the front plate glass 1 side, it is difficult to form a negative glow 9 due to the loss of charged particles to the front plate glass 1, and even if it is formed, it is unstable. Since the discharge light emission of the negative glow 9 is extremely limited as shown in FIGS. 3 and 4, the light emission brightness is low and the light emission efficiency is poor.

Note that when the thickness of the insulating layer 7 is in the range of 20λ _e to 25λ _e , negative glow 9 may be formed on the upper surface of the cathode electrode 3 on the front plate glass 1 side, and others may not be formed due to manufacturing variations in each discharge cell. Therefore, a stable discharge display cannot be expected as a whole.

Further, in order to form a negative glow on the upper surface of the cathode electrode 3, in addition to the thickness D of the above-mentioned loose edge layer 7, the discharge cell 10
It is also necessary to consider the hole diameter d ₁ of the cathode electrode 3 and the diameter d ₂ of the through hole 8 of the cathode electrode 3 .

In view of this, the present invention provides a method for adjusting the pore diameter of the discharge cell 10.
By appropriately selecting d ₁ , the diameter d ₂ of the through hole of the cathode electrode 3, and the distance D between the front plate glass 1 and the cathode electrode 3, a DC gas discharge display device with improved display brightness and luminous efficiency is provided. This is what I am trying to do.

Hereinafter, an embodiment of the DC gas discharge display device according to the present invention will be described in detail with reference to FIGS. 5 and 6. Housings corresponding to those in FIGS. 1 to 4 are designated by the same reference numerals. The duplicate explanation will be omitted.

In the DC type gas discharge display device according to the present invention, the thickness D of the discharge space 11 between the front plate glass 1 and the cathode electrode 3, which overflows the negative glow 9, is reduced by the equilibrium collision of electrons and ions in the plasma caused by the discharge. If the distance, that is, the mean free path of electrons is λ _e , the discharge cell pore diameter d ₁ , and the cathode electrode pore diameter d ₂ , then the range that satisfies both the expressions d ₁ > d ₂ and 25λ _e ≦d ₁ ≦500λ _e 25λ _e ≦D≦70λ _e .

That is, first, the discharge space 1 where the negative glow 9 overflows between the front plate glass 1 and the cathode electrode 3 is created.
1 is selected to be 25λ _e or more, which causes almost no loss of charged particles to the front plate glass 1, and 70λ _e or less, which allows the negative glow to be visually observed. For example, if the main component is Ne, gas pressure P
120 Torr. That is, if λ _e is 5 μm, D is 350 μm
Negative glow can be seen visually. Furthermore, in the present invention, the hole diameter d ₁ of the discharge cell 10 and the diameter d ₂ of the through hole 8 of the cathode electrode 3 are selected so that d ₁ > d ₂ so that the portion where the negative glow 9 is expanded and distributed is formed. so as not to be omitted,
Also, the discharge starting voltage is kept from becoming too high to be of practical use.

In addition, the pressure P of the gas that contributes to discharge is set to a lower limit value at which the sputtering phenomenon increases and the discharge starting voltage also increases.
The pore diameter d of the discharge cell 10 is set between 70 Torr. and the upper limit value 300 Torr., where so-called discharge concentration occurs, making it difficult to uniformly distribute the negative glow 9 over the entire cathode, and causing the discharge starting voltage to rise again. ₁ is selected to be 25λ _e ≦d ₁ ≦500λ _e so that a stable discharge display can be obtained.

That is, when the pore diameter d ₁ of the discharge cell 10 is reduced, the loss of charged particles to the insulating layer 7 increases, and the pore diameter d ₁ is reduced to 25λ _e
If it is selected below, stable discharge cannot be maintained, and it becomes extremely difficult to generate a negative glow on the upper surface of the cathode electrode 3. This loss of charged particles increases as the pressure P of the discharge gas decreases, so we conducted an experiment with the gas pressure P set to the lower value between 70 Torr and 300 Torr, and found that the pore diameter d ₁ lower limit of 25
λ _e is obtained. To give an experimental example, gas pressure P = 75 Torr. In other words, mean free path of electrons λ _e = 8 μm
When set to , the hole diameter d ₁ = 0.2 mm, and P =
100 Torr. That is, when λ _e = 6 μm, d ₁ = 0.15 mm
Even if d ₁ was reduced to 100%, stable generation of negative glow 9 on the upper surface of cathode electrode 3 was observed.

On the other hand, if the pore diameter d ₁ of the discharge cell 10 is increased,
The discharge area of the cathode electrode 3 increases, and the pore diameter d ₁ increases.
If it is selected to exceed 500λ _e , it becomes difficult to form a uniform negative glow over the entire cathode electrode 3. The unevenness of the negative glow distribution due to this discharge concentration becomes more pronounced as the pressure P of the discharge gas increases, so the experiment was conducted by setting the gas pressure P to the higher value between 70 Torr and 300 Torr. As a result, the upper limit of pore diameter d ₁ is 500
λ _e is obtained. To give an experimental example, P=
300 Torr. That is, when λ _e = 2 μm, d ₁ = 1.0 mm,
Further, when P=150 Torr., that is, λ _e =4 μm, even if d ₁ was increased to d ₁ =2.0 mm, a uniform negative glow was observed over the entire surface of the cathode electrode.

As described above, the thickness D of the discharge space 11 between the front plate glass 1 and the cathode electrode 3 through which the negative glow 9 overflows, the mean free path of electrons in the filled gas is λ _e , the discharge cell hole diameter d ₁ , The pore size of the cathode electrode
If d ₂ , then by selecting 25λ _e ≦D≦70λ _e within the range that satisfies both the expressions d ₁ > d ₂ and 25λ _e ≦d ₁ ≦500λ _e , the negative glow 9 is emitted from the top surface of the cathode electrode 3. The negative glow 9 is distributed around the edge of the through hole 8 and toward the lower surface of the cathode electrode 3, and the thickness of the negative glow 9 increases in the vertical direction, which is the display direction. The state of the light emitting display when visually observed from the front plate glass 1 side is not only around the edge of the through hole 8 but also on the front plate glass 1 outside the through hole 8, and the light emitting display area increases dramatically. . As a result, the brightness and luminous efficiency of the discharge display are improved, and the amount of metal material deposited from the cathode electrode 3 due to the spatter phenomenon is reduced, which helps extend the life of the gas discharge display device.

The following is a further explanation based on experimental data.

What is shown in Figure 7 is experimental data showing the reason for choosing D as 25λ _e ≦D ≦70λ _e . That is, D
Seven types of discharge tubes with values of 50, 150, 200, 300, 400, 500, and 600 (all in μm) were made, and d ₂ /
_d1 was selected to be 0.67 for each tube, 100% Ne gas was filled in as the discharge gas, and the filled gas pressure was set to 75, 150, 150,
225 and 300 (both Torr), visually observe the discharge state, and from this visual observation, the discharge state is A,
The table is divided into four categories: B, C, and D.

A is a state in which a small amount of negative glow is generated only inside the through hole 8 of the cathode electrode 3, as shown in FIG. 9, and B is a state in which a small amount of negative glow is generated on the surface of the cathode electrode 3, as shown in FIG. C indicates a state in which a small amount of negative glow oozes out from the cathode electrode 3 as shown in FIG.
As shown in Figure 12, D shows a state in which negative glow is generated on a part of the surface of the cathode electrode 3. Therefore, not only state C but also state B is effective in use.

In Figure 7, if the Ne gas pressure is determined, the mean free path λe of the electron can be found, so
This λe is shown in parentheses for each gas pressure.

Since λe can be found for each gas pressure in this way, the ratio between λe and D can be determined. In Figure 7, these ratios are shown in parentheses. For example, when D is 50μm, gas pressure is 75Torr, 50μm≒6.3×8μ
m, that is, D≒6.3λe.

If state A is excluded from this, D becomes D≧25λe. In other words, if D becomes less than 24λe, due to loss of charged particles to the front plate glass 1, etc.
This prevents negative glow from seeping onto the cathode surface.

Also, according to Figure 7, D is 200λe, 300
It shows a good discharge condition even if it is as large as λe. In fact, the larger D is, the better the negative glow will be produced. However, such display devices are not always visible only from the front. In other words, it can be viewed from an oblique direction, and unless it can be seen even in this case, it is of no use. In this case, the larger the value of D, the more the discharge occurs at the back of the display panel, making it difficult to visually see it from an oblique direction.

The present inventor has determined the size of D at which the negative glow discharge becomes a certain amount (a certain amount of light that can be put into practical use) when viewed from a certain angle (for example, 60 degrees) with respect to the perpendicular line in front of the display panel. After calculating the D value, we found that if D was greater than 70λe, it would not be possible to obtain a sufficient amount of light for practical use.

For the above reasons, 25λe≦D≦70λe was obtained.

To explain Fig. 8, cathode electrode 3
The diameter d ₁ of the through hole 8 is 100, 200, respectively.
6 of 500, 1000, 2000 and 3000 (all μm)
Make different types and add 100% Ne to each of them.
Fill with gas and use 75, 150, 225 and
We changed the gas pressure to 300 (Torr) and visually observed the occurrence of negative glow. A, B, C, and D listed in the table are the same as above.
In addition, d ₂ /d ₁ is also selected as 0.67 as above, and D is 250
I chose μm. Furthermore, d ₁ in parentheses was calculated in the same way as in Figure 7.

As is clear from Fig. 8, when d ₁ becomes smaller than 25λe, negative glow occurs only within the through hole 8 as shown in Fig. 9, which is not desirable. or
If d ₁ exceeds 500λe, negative glow will occur partially as shown in Figure 12, which is also not desirable. These reduce d ₁ to 25λ
It is selected such that e≦d ₁ ≦500λe.

In addition, in each of the above-mentioned examples, the discharge gas was 100%
However, almost the same results as above were obtained when 0.5% Ar gas and 0.2% Xe gas were filled with Ne gas. .

According to the DC discharge type gas discharge display device of the present invention, a stable discharge operation can be performed, and the negative glow can be distributed around the edge of the through hole of the cathode electrode to extend toward the front plate glass side. Therefore, display brightness and luminous efficiency can be dramatically improved.

[Brief explanation of the drawing]

1 and 3 are sectional views of main parts of a conventional gas discharge display device, and FIGS. 2 and 4 are sectional views of the main parts of a conventional gas discharge display device.
FIG. 5 is a sectional view of essential parts of an embodiment of the gas discharge display device according to the present invention; FIG. 6 is a plan view showing the glow discharge state of FIG. 5; FIG. 7 is a plan view showing the glow discharge state of FIG. 12 are diagrams for explaining the present invention based on experimental results. 1 is a front plate glass, 2 is a back plate glass, 3 is a cathode electrode, 4 is an anode electrode, 8
9 is a through hole of the cathode electrode 3, 9 is a negative glow, 10 is a discharge cell, and 11 is a discharge space of the negative glow 9.

Claims (1)

[Scope of Claims] 1. A cathode electrode having a small hole arranged opposite to an anode electrode, with the small hole facing a negative glow overflow space formed between the cathode electrode and the front plate. sealed inside the outer casing with
In the DC gas discharge display device, a negative glow discharge is caused in the negative glow overflow space including the periphery of the small hole of the cathode electrode by applying a voltage between the two electrodes. When D is the mean free path of electrons, λe is the pore diameter of the negative glow _{overflow space, and d 2 is the diameter of the small hole in the cathode electrode, d 1 > d 2 and 25λe ≦} d ₁ ≦500λe A direct current type gas discharge display device characterized in that 25λe≦D≦70λe is selected within a range that satisfies both formulas.