JP2002334659A - Plasma display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma display panel with high brightness of which, light emitting property is improved not only by effectively utilizing visible light emitted from a phosphor, but also by effectively utilizing ultraviolet ray. SOLUTION: For the plasma display panel having a plurality of discharge cells separated by a separation wall 8 formed on a substrate 5, having a phosphor layer 9 at its inside, glass beads 20, having ultraviolet ray surface reflection property and visible light retroreflection property, are distributed at the lower layer side of the phosphor layer 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a plasma display panel, and more particularly to a plasma display panel having improved emission characteristics of a phosphor layer in a discharge cell.

[0002]

2. Description of the Related Art Plasma display panels (PDPs)
Is in an airtight space formed between a pair of parallel flat substrates,
A plurality of discharge cells are formed in a striped or matrix shape, and an image is displayed by selectively generating a discharge in the plurality of discharge cells.

FIG. 5 is an explanatory view showing a general structure of a plasma display panel. Reference numeral 1 denotes a front glass substrate, on which a display electrode 2, a dielectric layer 3, and a protective film 4 such as MgO (magnesium oxide) are provided. Reference numeral 5 denotes a back glass substrate, on which address electrodes 6, address protection layers 7 and partition walls 6 having a predetermined shape are formed. The fine space defined by the front glass substrate 1, the rear glass substrate 5, and the partition walls 6 is the above-described discharge cell. In each of the discharge cells, an address electrode 6 is provided, and a phosphor layer of each of RGB colors is provided. 9 (9a, 9b, 9c) are formed. Further, a discharge gas in which neon, xenon, or the like is mixed is injected into the discharge cell.

In such a plasma display panel, a voltage is applied between the display electrode 2 and the address electrode 6,
An image is displayed by selectively discharging and emitting light from the phosphor layer 9 formed on the inner surface of the discharge cell. A black stripe 10 is formed on the rear surface of the front glass substrate 1 so as to correspond to the upper surface of the partition 8. In the example shown,
The partition walls 8 are formed in a grid pattern, and the discharge cells are arranged in a matrix. As a form of the discharge cells, there is a method in which the partition walls 8 are formed in parallel to form stripe-shaped discharge cells.

FIG. 6 is a sectional view showing a discharge cell of the above-mentioned conventional plasma display panel. According to this, when a voltage is applied between the display electrode 2 and the address electrode 6, plasma discharge occurs in the discharge cell,
Ultraviolet light generated by this plasma discharge is applied to the phosphor layer 9.
Is excited, and RGB visible light is emitted as display light from the phosphor.

[0006]

The phosphor excited by ultraviolet rays emits visible light isotropically around the phosphor particles and emits light in all directions. That is, the visible light emitted from the phosphor is emitted from the phosphor directly to the front of the plasma display panel, and is emitted to the front of the plasma display panel by changing the direction by repeating reflection in the discharge cell. Only the light is visually recognized as display light, and other emitted light is absorbed by discharge cell constituent members such as partition walls or becomes leakage light emitted from the back side, thereby improving the brightness of the plasma display panel. It will be a loss in doing so.

In order to cope with this, there has been proposed a method in which an address electrode provided on the bottom surface of a discharge cell is formed of a material having a high reflectance. However, when the material of the address electrode is made of a material having a high reflectivity, there is a problem that the material of the electrode is limited, and the electrical characteristics that should be originally required cannot be made sufficient, and the formation of the electrode becomes difficult. There is also a problem that it is impossible to prevent light leakage from gaps that are not formed. As another measure, the phosphor layer itself is formed of a phosphor having a high visible light reflectance. The emission characteristics originally required
This is an obstacle to pursuing something higher.

On the other hand, when the phosphor layer is thickened in anticipation of an increase in the amount of light emission, the phosphor on the surface layer blocks ultraviolet rays, and the ultraviolet rays do not reach the phosphor inside the layer, resulting in a decrease in luminous efficiency. Because of the problem, a method of forming the phosphor layer in a porous shape, mixing a phosphor which is excited by ultraviolet rays and further emits ultraviolet rays in the inside of the phosphor layer is adopted. When such a method is adopted, the ultraviolet rays reach the bottom surface of the phosphor, but the ultraviolet rays passing through the phosphor layer are generated without contributing to the excitation of the phosphor. Is reduced.

The present invention has been proposed in order to cope with such circumstances, and effectively utilizes visible light emitted from a phosphor as display light and effectively utilizes ultraviolet light. An object is to improve the luminous efficiency of the phosphor.

[0010]

In order to achieve the above object, a plasma display panel according to the present invention has the following arrangement.

According to a first aspect of the present invention, there is provided a plasma display panel including a plurality of discharge cells partitioned by a partition formed on a substrate and having a phosphor layer therein, wherein the lower side of the phosphor layer is provided. And glass beads having visible light retroreflection property are arranged thereon.

According to a second aspect of the present invention, in the plasma display panel according to the first aspect, the glass beads have an ultraviolet surface reflectivity.

According to a third aspect of the present invention, in the plasma display panel according to the first or second aspect, the glass beads are disposed on at least one of a surface layer of the partition wall and a bottom protective layer of the discharge cell. It is characterized by that.

According to a fourth aspect of the present invention, in the plasma display panel according to the first or second aspect, the glass beads are arranged on a reflective layer formed on the inner surface of the discharge cell.

According to a fifth aspect of the present invention, in the plasma display panel according to any one of the first to fourth aspects, the glass beads have a refractive index of 1.5 to 1.7.

The invention according to each of the above-mentioned claims has the following effects by having the above-described configuration.

According to the first aspect of the invention, the visible light emitted from the phosphor and directed to the lower layer side of the phosphor layer is returned to the front side of the panel by the visible light retroreflection action of the glass beads. Therefore, the emitted visible light can be effectively used as display light. In addition, since the emitted light having an angle with respect to the front direction can be surely reflected and emitted from the front side of the panel, the luminance in a wide viewing angle region can be increased, and the viewing angle can be increased. it can.

According to the second aspect of the present invention, the ultraviolet rays reaching the lower layer of the phosphor layer can be reflected inside the phosphor layer by the ultraviolet surface reflection effect of the glass beads disposed below the phosphor layer. As a result, the utilization efficiency of the generated ultraviolet light increases, and the luminous efficiency of the phosphor can be improved. In addition, the visible light emitted from the phosphor and directed to the lower layer side of the phosphor layer is returned to the front side of the panel by the visible light retroreflection action of the glass beads, so the emitted visible light is effective as display light. Can be used for

According to the third aspect of the present invention, in addition to the above-described effects, in the barrier layer and the bottom surface protective layer of the discharge cell, a loss is caused by being absorbed on the surface or passing through the surface. It is possible to effectively use the ultraviolet light and visible light that have been used.

According to the fourth aspect of the present invention, the utilization ratio of ultraviolet light and visible light is improved by the reflective layer formed on the inner surface of the discharge cell, and the ultraviolet light and visible light which are not used due to irregular reflection on the surface of the reflective layer are further improved. It can be effectively used by the presence of glass beads.

According to the fifth aspect of the present invention, by setting the refractive index of the glass beads to 1.5 to 1.7, the visible light incident on the glass beads is fed back in substantially the same direction, and the discharge cells are surely formed. Since it is returned to the inside, the effective use of visible light is improved.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings (the same parts as those in the prior art are denoted by the same reference numerals, and redundant description will be omitted). FIG. 1 is an explanatory diagram showing a discharge cell of a plasma display panel according to one embodiment of the present invention. The structure of the discharge cell itself is the same as the conventional one. In this embodiment, glass beads 20 are arranged below the phosphor layer 9.

The structure and operation of the glass beads 20 will be described with reference to FIG. The glass beads 20
Glass particles having a particle size of 5 to 20 μm, which is approximately the same as the particle size of the phosphor, having a refractive index of approximately 1.5 to 1.7, and a thin film coating 21 for reflecting ultraviolet light on the surface thereof. It has been subjected. The thin film coating 21 is formed by depositing an ultraviolet reflecting material such as chromium on the surface. The glass beads 20 having such a structure have ultraviolet surface reflection and visible light retroreflectivity.

According to the ultraviolet surface reflectivity, the ultraviolet light (c in the figure) reaching the lower layer of the phosphor layer 9 is
Is reflected by the surface of the phosphor layer, the direction is changed, and the light is emitted again to the phosphor layer 9. As a result, the reflected ultraviolet light irradiates the not-excited phosphor in the phosphor layer 9 and excites the same, so that the utilization efficiency of the ultraviolet light increases, and at the same time, the luminous efficiency of the phosphor layer increases. improves.

The visible light retroreflectivity will be described. When visible light (a1, a2) emitted from the phosphor and emitted toward the lower layer of the phosphor layer 9 is incident on the glass beads 20, This is the function of (b1, b2) reflecting this on the inner surface and emitting in the opposite direction substantially parallel to the incident light.
To obtain this effect, the refractive index of the glass beads 20 is an important factor, and by selecting this as 1.5 to 1.7, a reliable visible light retroreflection characteristic can be obtained.

To further describe the advantage of the visible light reflection characteristic, when the glass beads 20 are not provided, even if a reflective layer is formed on the inner surface of the discharge cell, the visible light incident on the reflective layer surface is not affected by the visible light. Light that is reflected in various directions due to irregular reflection on the surface and the like and is returned in the same direction and can be effectively used is reduced to about 50% (when the incident angle is about 30 °). On the other hand, when the visible light retroreflective glass beads 20 are provided, the visible light incident on the glass beads 20 returns almost 100% in the same direction. Even if the transmittance is 75%, 0.75 × 0.75 = 0.56, and 56% return light is obtained. This is 12% more efficient than without glass beads.

When the glass beads having such a visible light retroreflective property are employed, of the visible light emitted from the phosphor in all directions, the component absorbed by the partition walls 8 and the address protection layer 7 and lost. When a reflective layer is provided, components that cannot be used due to irregular reflection on the surface can be efficiently returned to the incident direction, and display luminance can be increased by increasing the amount of light returning to the discharge space. In particular, emission light having an angle with respect to the front direction can be surely reflected by the glass beads and emitted from the front side of the panel, so that luminance in a wide viewing angle region can be increased and the viewing angle can be increased. Can be enlarged.

In the above embodiment, the glass beads 20 are provided with the thin film coating 21, but the thin film coating 21 is not always necessary. A certain degree of ultraviolet reflectivity can be obtained only by the surface of the glass beads 20, and the effect of improving brightness and expanding the viewing angle can be obtained only by the visible light retroreflectivity of the glass beads 20 alone.

Next, an embodiment of a place where the glass beads 20 are installed will be described with reference to FIGS. In the embodiment of FIG. 3, the glass beads 20 are provided on the surface layer of the partition wall 8 and also on the address protection layer (bottom protection layer of the discharge cell) 7 on the rear glass substrate 5. According to this, the visible light a emitted from the excited phosphor 91 in the phosphor layer 9 and conventionally absorbed by the partition 8 or the address protection layer 7 is used.
However, due to the visible light retroreflection characteristics of the glass beads 20,
It is effectively utilized as visible light b returning to the discharge space.
In addition, the ultraviolet light c that has reached the lower layer of the phosphor layer 9 and has been absorbed by the partition walls 8 and the address protection layer 7 is changed to the glass beads 20.
Is reflected by the surface of the phosphor layer 9 to excite the phosphor 92 in the phosphor layer 9 which has not been excited yet. In the figure, the glass beads 2 are provided on both the partition 8 and the address protection layer 7.
Although the example where 0 is provided is shown, it may be provided on either one of the partition wall 8 or the address protection layer 7, and in this case, needless to say, a sufficient effect can be obtained as compared with the case where the glass beads 20 are not provided. No.

In the embodiment shown in FIG. 4, the glass beads 20 are arranged on the reflection layer 11 formed on the inner surface of the discharge cell. In this case, ultraviolet light and visible light can be effectively returned to the discharge space side by surface reflection and retroreflection of the glass beads 20. According to this, the reflection layer 11
And a more effective increase in luminance can be obtained in combination with the reflection of ultraviolet light and visible light.

According to each of the above-described embodiments, the emitted visible light and the generated ultraviolet light can be used effectively, the emission characteristics of the phosphor layer are improved, and a high-luminance plasma display panel is formed. Can be.

Hereinafter, a method of forming the plasma display panel according to the above-described embodiment will be described. The formation of the discharge cell itself is the same as the conventional method, and
An address electrode 6, an address protection layer 7, and a partition 8 are formed thereon. Then, the reflection layer 11 is formed on the inner surface of the discharge cell partitioned by the partition 8. The reflection layer 11 is made of titanium oxide,
A material having high reflectivity such as barium sulfate is kneaded with a binder such as an acrylic resin and applied by a screen printing method or the like.

After the formation of the reflective layer 11, the glass beads 20 are disposed thereon. As described above, the glass beads 20 are formed by coating glass particles having a particle size of about 5 to 20 μm with an ultraviolet reflecting material such as chromium by vapor deposition. In forming the coating film thickness, the reflection characteristics of ultraviolet light and the transmittance of visible light are adjusted by the thickness. The refractive index of the glass beads 20 is set to 1.5 to 1.7 at which the visible light retroreflectivity can be obtained.

As for the method of arranging the glass beads 20, similarly to the formation of the above-mentioned reflective layer 11, a method of mixing the glass beads 20 with an acrylic transparent binder and applying the mixture by a screen printing method, or a method of dispersing a spacer is used. A method of directly applying on the reflective layer is employed. Then, after the glass beads 20 are arranged, R, G, B
A phosphor layer of each color is formed in the discharge cell.

In the above description, an example in which the reflective layer 11 is formed and the glass beads 20 are disposed thereon has been described. However, the glass beads 20 are directly formed on the partition 8 and the address protection layer 7 without forming the reflective layer 11. When the glass beads 20 are mixed with the partition wall material and the material of the address protection layer, and the partition walls 8 and the address protection layer 7 are formed by this, the partition walls having a part of the glass beads 20 buried in the surface layer are formed. 8. Address electrodes 7 can be formed. In this case, glass beads 20 are mixed as a kind of filler into the material for forming the partition walls or the address protection layer to make the material base. In this case, the mixing amount of the glass beads is determined by taking into consideration the coefficient of thermal expansion of the partition 8 or the address protection layer 7 in consideration of the coefficient of thermal expansion of the rear glass substrate 5 to which the partition 8 or the address protection layer 7 is applied. Adjust to a value close to the expansion coefficient.
Incidentally, when the glass beads 20 are mixed into the partition wall material and the address protection material, their thermal expansion coefficients are reduced.

In the plasma display panel of the present invention, the form of the discharge cells is not particularly limited. That is, the present invention is also applicable to a discharge cell having a matrix arrangement partitioned by barrier ribs formed in a grid pattern on a substrate, and a discharge cell having a stripe arrangement partitioned by partition walls formed in parallel on a substrate. Can be applied.

[0037]

Since the present invention is configured as described above,
By disposing glass beads having an ultraviolet surface reflection property and a visible light retroreflection property on the lower layer side of the phosphor layer of the discharge cell, the visible light emitted from the phosphor can be effectively used as display light, and Can be effectively used to improve the luminous efficiency of the phosphor, thereby improving the luminous characteristics of the phosphor layer and providing a high-luminance plasma display panel.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a discharge cell of a plasma display panel according to one embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the structure and operation of a glass bead according to the embodiment.

FIG. 3 is an explanatory diagram showing a main part of a plasma display panel according to another embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a main part of a plasma display panel according to another embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a structure of a general plasma display panel.

FIG. 6 is a cross-sectional view illustrating a discharge cell of a general plasma display panel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Front glass substrate 2 Display electrode 3 Dielectric layer 4 Protective layer 5 Back glass substrate 6 Address electrode 7 Address protective layer 8 Partition 9 Phosphor layer 10 Black stripe 11 Reflective layer 20 Glass beads 21 Thin film coating

Claims (5)

[Claims] 1. A plasma display panel comprising a plurality of discharge cells partitioned by a partition formed on a substrate and having a phosphor layer therein, wherein a visible light retroreflection is formed on a lower layer side of the phosphor layer. A plasma display panel comprising glass beads having a characteristic. 2. The plasma display panel according to claim 1, wherein the glass beads have an ultraviolet surface reflectivity. 3. The plasma display panel according to claim 1, wherein the glass beads are disposed on at least one of a surface layer of the partition wall and a bottom protective layer of the discharge cell. 4. The plasma display panel according to claim 1, wherein the glass beads are disposed on a reflection layer formed on an inner surface of the discharge cell. 5. The glass beads having a refractive index of 1.5 to 1.5.
The plasma display panel according to any one of claims 1 to 4, wherein 1.7 is set.