JP3042432B2 - Color plasma display panel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a color plasma display panel. More specifically, the present invention relates to a color plasma display panel in which maintenance of display luminance and further improvement of a contrast ratio under external light are compatible.

[0002]

2. Description of the Related Art In recent years, a color plasma display panel (hereinafter referred to as a color PDP) has been regarded as a promising device for realizing a large flat panel.
The color PDP excites the three primary color phosphor layers formed in the panel by ultraviolet rays generated by gas discharge,
A color image is displayed by emitting light spontaneously. Therefore, large panels can be manufactured at relatively low cost, wide viewing angles,
It is known to have advantageous features such as good color reproduction and fast response speed.

[0003] A conventional color PDP will be described below with reference to the drawings.

FIG. 7 is a partial cross-sectional view of one example of a conventional color PDP, and FIG. 8 is a partial perspective view showing the structure of the color PDP shown in FIG.

[0005] As shown in FIG.
Are the front substrate 101 on the image display side and the front substrate 1
And a rear substrate 102 provided opposite to the first substrate 101, and a discharge space 103 is formed between the front substrate 101 and the rear substrate 102.

On the front substrate 101, a large number of sustain electrodes 105 for maintaining a discharge for generating ultraviolet light are provided on the surface of the front substrate glass 104 located on the outermost surface of the color PDP facing the rear substrate 102. I have. Sustain electrode 10
5 is provided with a dielectric layer 106 made of low-melting glass on the surface thereof, and MgO is formed on the surface thereof.
A protective layer 107 made of a deposited film is formed. Further, on the surface, as shown in FIG. 8, a front partition wall 109a formed in a lattice shape is provided. As shown in FIG. 8, the sustain electrode 105 is composed of a transparent electrode 105a and a bus electrode 105b. One cell 114 surrounded by the lattice-shaped front partition 109a has two sustain electrodes. The electrodes 105 are arranged in pairs and are provided in parallel with each other.

[0007] As shown in FIG.
Address electrodes 111 are provided on the upper surface of rear substrate glass 108 in a direction orthogonal to sustain electrodes 105. Each address electrode 111 has a number of rear-side partition walls 109b provided in parallel and at equal intervals on the upper surface of the rear substrate glass 108.
By combining the back side partition 109b and the front side partition 109a,
A large number of discharge cells 110 serving as units for generating plasma discharge are formed. Further, a phosphor layer 112 is printed on at least the bottom surface of each discharge cell 110. The phosphor layer 112 includes a red phosphor layer 112a, a blue phosphor layer 11
2b, a green phosphor layer 112c is used.
12a, 112b and 112c are regularly applied to the respective discharge cells 110 in stripes.

In a space between the front substrate 101 and the rear substrate 102, a Xe gas that generates ultraviolet rays by electric discharge is provided.
A mixed gas 113 with Ne gas or He gas, which is a main discharge gas, is sealed.
It has become.

In discharge cell 110, when a voltage is applied between one sustain electrode 105 of two pairs of sustain electrodes 105 and address electrode 111, discharge space 103 is discharged.
Gas discharge occurs and ultraviolet rays are generated. The ultraviolet light excites the phosphor layer 112 on the rear substrate 102 to emit visible light. The light emitted in this manner is applied to the front substrate 1
01, the emitted light is transmitted through the front substrate 101 directly after light emission, and is emitted to the outside. Some light is transmitted and emitted. The color image is displayed on the display by the emitted light emitted as described above.

Note that, as shown in FIG.
White reflective layer 1 that reflects all wavelengths of visible light underneath
14 when the emitted light is reflected by the inner surface of the discharge cell 110 as described above.
There is also known a light-emitting device improved so that emitted light is not absorbed as much as possible. This makes it difficult for the emitted light to be absorbed by the partition walls 109 and the like when reflected on the inner surface of the discharge cell 110, and the emitted light is efficiently reflected to improve display luminance.

However, in the above-described conventional example, when external light, which is white light, enters from the front substrate 101 side, it is reflected on the surface of the phosphor layer 112,
2 is reflected on the surface of the discharge cell 110, so that the contrast ratio is reduced, and the display quality of an image is reduced. In particular, in a color PDP, the effect of reflection by the reflection layer 114 is generally greater than the surface of the phosphor layer 112, and therefore, the reflection layer 11 is formed below the phosphor layer 112.
In the case where No. 4 is provided, the external light is strongly reflected by the white reflective layer 114, so that the problem becomes remarkable.

On the other hand, as shown in FIG. 10, disposing the ND filter 115 on the surface of the front substrate glass 104 is the simplest means for improving the reduction of the contrast ratio under external light. Absorbs not only external light but also emitted light, so that the contrast ratio is improved, but the display luminance is also reduced accordingly. As shown in FIG. 11, a means for preventing reflection of external light by applying a pigment or the like that absorbs light other than the wavelength of emitted light on the phosphor layer 112 may be considered. Since the exciting ultraviolet light is also absorbed, the luminous efficiency is reduced and the display luminance is reduced.

Therefore, as a color PDP for improving the contrast ratio without lowering the display brightness, for example, Japanese Patent Application Laid-Open Nos. 8-138559 and 4-476.
No. 40 is disclosed.

As shown in FIG. 12, the color PDP disclosed in Japanese Patent Application Laid-Open No. 8-138559 reflects a wavelength component of emitted light and absorbs other wavelength components instead of the above-mentioned reflective layer 114. In this case, a wavelength selective reflection layer 116 made of a reflective film is formed. Wavelength selective reflection layer 1
In 16, a pigment or the like corresponding to each emission color of the phosphor layer 112 is applied or mixed.

According to the above configuration, external light that has entered the discharge cell 110 from the front substrate 101 side and has passed through the phosphor layer 112 is reflected by the wavelength selective reflection layer 116.
The same wavelength component as the emitted light is reflected, and the other wavelength components are absorbed. On the other hand, about half of the light emitted from the phosphor layer 112 is emitted to the front substrate 101 side and is emitted to the outside as it is. The other half of the emitted light is
The light is radiated to the second side, is reflected by the wavelength selective reflection layer 116, and is radiated to the outside. As described above, the contrast ratio is improved without significantly lowering the display luminance.

As shown in FIG. 13, a color PDP disclosed in Japanese Patent Application Laid-Open No. 4-47640 transmits a wavelength component of emitted light to a lower surface of a front substrate glass 104, and transmits other wavelength components. Is provided with a filter layer 117 that absorbs light. The filter layer 117 includes a red filter 117a and a green filter 117 according to each emission color of the phosphor layer 112 applied to the discharge cell 110 located thereunder.
b, blue filter 117c.

According to this configuration, external light is transmitted to the front substrate 101.
When the light enters the discharge cell 110 from the side, the filter layer 1
At this time, among the wavelength components of the external light, the same wavelength component as the emitted light is transmitted, and the other wavelength components are absorbed. Further, the external light thus incident is reflected on the surface of the phosphor layer 112 and the surface of the discharge cell 110 and is emitted to the outside. At this time, the external light from which unnecessary wavelength components have been removed at the time of the incident is again reflected. By transmitting the light through the filter layer 117, unnecessary wavelength components of the external light are further removed. On the other hand, when the emitted light passes through the filter layer 117, it is transmitted efficiently. As described above, the contrast ratio has been improved without lowering the display luminance.

[0018]

The above-mentioned JP-A-8-13
In the color PDP disclosed in Japanese Patent No. 8559, when external light is reflected by the wavelength selective reflection layer, many unnecessary wavelength components of the external light are absorbed. Furthermore, about half of the light emitted from the phosphor layer is emitted toward the front substrate,
Since the light is radiated to the outside without being reflected by the wavelength-selective reflective layer, the minute attenuation of the emitted light due to reflection by the wavelength-selective reflective layer is reduced to about half that of the case where all the emitted light passes through the filter layer. Can be.

However, in order to efficiently absorb unnecessary wavelength components of external light, it is necessary to form a wavelength-selective reflection layer with a sufficient thickness. However, plasma discharge is efficiently generated in a narrow discharge cell. There is a limit to making it thicker. Therefore, the thickness of the formed wavelength selective reflection layer must be insufficient, and the external light is emitted to the outside while still having unnecessary wavelength components.
Therefore, the display luminance can be maintained, but the improvement of the contrast ratio is insufficient.

In the color PDP disclosed in Japanese Patent Application Laid-Open No. 4-47640, since external light passes through the filter layer at least twice before entering the discharge cell and exiting, the external light has Regarding the removal of unnecessary wavelength components, a better effect can be obtained than in the conventional example. However, since the filter layer is provided on the front substrate, there has been a problem that the manufacturing process of the front substrate is complicated and the material of the pigment used for the filter layer is limited. That is, since the manufacturing process of the front substrate includes a high heat treatment step at about 500 ° C. to 600 ° C., it is necessary to select a material that is hardly affected by the heat treatment.

Further, in the present color PDP, all the light emitted from the phosphor layer passes through the filter layer and is radiated to the outside. Therefore, the light emitted by the filter layer is attenuated to a small extent by passing through the filter layer, and the display luminance is reduced. Was a factor in the decline.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a color plasma display panel which can maintain the display luminance and further improve the contrast ratio under external light, and can realize good display quality.

[0023]

In order to achieve the above object, a color plasma display panel according to the present invention has a front substrate for displaying an image, and a back substrate facing the front substrate. A large number of partition walls and address electrodes are provided side by side on the surface facing the front substrate, whereby a discharge cell serving as a unit for generating plasma discharge is formed in a region partitioned by the partition walls, In a color plasma display panel in which a phosphor layer is provided on at least a bottom portion of the discharge cell,
Between the bottom surface portion of the discharge cell and the phosphor layer, a white reflective layer that reflects all visible light wavelengths, and furthermore, an emission light generated from the phosphor layer on the reflective layer. A filter layer that transmits a wavelength component.

About half of the light emitted from the phosphor layer is emitted toward the front substrate, and the other half is emitted toward the rear substrate. Here, since the filter layer is provided on the rear substrate side, the emitted light emitted to the front substrate side is emitted to the outside without passing through the filter layer, so that all the emitted light passes through the filter layer. As compared with the conventional example, a decrease in display luminance is suppressed. In addition, since external light reflected by the reflective layer and emitted to the outside is transmitted at least twice through the filter layer, absorption efficiency of unnecessary wavelength components of the external light is high.

The thickness of the phosphor layer is set such that the reflectance of the phosphor layer alone on the surface of the phosphor layer with respect to white light is 50% or less. The lower contrast ratio is significantly improved.

Further, the reflectance of the combination of the filter layer and the reflection layer may be adjusted to the same wavelength as the emission light in the process of transmitting the emission light and the white light through the filter layer and reflecting on the reflection layer. Component reflectance is 70
% And the reflectance of wavelength components other than the wavelength component of the emitted light is desirably set to 30% or less.

Further, since the inorganic pigment powder, the metal powder and the metal film all reflect external light which is white light, any of them can be used for forming the reflection layer.

Further, if an address electrode provided on the back substrate is used as the metal film, it is not necessary to separately provide the reflective layer.

[0029]

Next, embodiments of the present invention will be described with reference to the drawings.

(First Embodiment) FIG. 1 is a partial sectional view of a color plasma display panel according to a first embodiment of the present invention.

As shown in FIG. 1, a color plasma display panel 1 (hereinafter, referred to as a color PDP 1) of the present embodiment is provided with a front substrate 2 on which an image is displayed, and opposed to the front substrate 2. And a discharge space 4 is formed between the front substrate 2 and the rear substrate 3.

The front substrate 2 has a surface facing the rear substrate of the front substrate glass 5 located on the outermost surface of the color PDP 1,
A large number of sustain electrodes 6 are provided for maintaining a discharge for generating ultraviolet light. A dielectric layer 7 made of low-melting glass is formed on the surface on which the sustain electrode 6 is provided, and a protective layer 8 made of an MgO vapor-deposited film is formed on the surface. Further, on the surface, a front side partition wall 10a formed in a lattice shape is provided similarly to the conventional example shown in FIG. Similarly to the conventional example shown in FIG. 8, the sustain electrode 6 includes a transparent electrode 6a and a bus electrode 6b (both not shown), and is surrounded by the lattice-shaped front-side partition 10a. One cell has two sustain electrodes 6
Are arranged in pairs and are provided in parallel with each other.

The rear substrate 3 has an address electrode 12 provided on the upper surface of the rear substrate glass 9 in a direction perpendicular to the sustain electrodes 6, as in the conventional example shown in FIG. Each address electrode 12 is partitioned by a large number of rear-side partitions 10b provided at equal intervals in parallel with the upper surface of the rear substrate glass 9, and the rear-side partitions 10b and the front-side partitions 10a are combined. As a result, a large number of discharge cells 11 serving as units for generating plasma discharge are formed.

At least the bottom of each discharge cell 11
A white reflective layer 15 made of a white pigment powder such as titanium oxide and reflecting all wavelengths of visible light is printed by a screen printing method and baked. In addition, the reflective layer 15 may be provided on the surface of the partition wall 10 which is the side surface of the discharge cell 11. On the reflective layer 15, a filter layer 16 that transmits the same wavelength component as the emitted light and absorbs other wavelength components is provided. On the filter layer 16,
Further, the phosphor layer 13 is provided by being printed by a screen printing method and baked.

The phosphor layer 13 includes (Y, Ga) BO ₃ :
Red phosphor layer 13a made of Eu, Zn ₂ SiO ₄ : Mn
Green phosphor layer 13b made of BaMgAl ₁₄ O ₂₃ : E
A blue phosphor layer 13c made of u ²⁺ is used, and each of the phosphor layers 13a, 13b, and 13c is regularly applied to each discharge cell 11 in stripes.

The filter layer 16 is classified into three colors by a pigment corresponding to each emission color of the phosphor layer 13 provided thereon, and a red filter 16a, a green filter 16b, and a blue filter 16c are formed. . That is, the discharge cell 11 provided with the red phosphor layer 13a is provided with the red filter 16a that transmits the wavelength component efficiently and absorbs the other wavelength components. The same applies to green and blue.

In this embodiment, since the filter layer 16 is provided on the rear substrate 3, there is no need to consider a high heat treatment step, and a material which is relatively easily affected by the heat treatment can be used. In particular, when an inorganic material is used for the pigment, ferric oxide (red), Co
O · nZnO (green), such as CoO · nAl ₂ O ₃ (blue) are known.

In the space between the front substrate 2 and the rear substrate 3, a mixed gas 14 of Xe gas which generates ultraviolet rays by discharge and Ne gas or He gas which is a main discharge gas is provided.
And this space is the discharge space 4.

In the discharge cell 11, when a voltage is applied between one of the two sustain electrodes 6 forming a pair and the address electrode 12, gas discharge occurs in the discharge space 4. UV rays are generated. This ultraviolet light excites the phosphor layer 13 on the back substrate 3 to emit visible light. Note that, of the phosphor layer 13, the one that is excited by the ultraviolet light is a light emitting region near the surface of the phosphor layer 13. The light emitted in this manner is transmitted through the front substrate 2 and emitted, and a color image is displayed on the display.

The radiation path from which the above-mentioned light is emitted will be described with reference to FIG. FIG. 2 is an enlarged cross-sectional view of the bottom surface of the discharge cell 11. As described above, the bottom surface of the discharge cell 11 is formed with a reflective layer 15, a filter layer 16, and a phosphor layer 13 in order from the bottom. is there.

The emitted light is radiated outside through the following two paths, a radiation path 17a and a radiation path 17b. In other words, about half of the light emitted from the phosphor layer 13 is radiated directly to the outside by the radiation path 17 a without being reflected by the reflective layer 15. Further, about half of the emission light generated in the phosphor layer 13 travels in the lower layer direction by the radiation path 17b, passes through the filter layer 16 and is reflected by the reflection layer 15, then passes through the filter layer 16 again, and The light is radiated to the outside while repeating inter-layer multiple reflection accompanied by transmission of the filter layer 16 between the lower surface of the layer 13 and the surface of the reflective layer 15.

That is, assuming that the total amount of light emitted from the phosphor layer 13 is 1, the reflectance of the phosphor layer 13 is Rp, and the reflectance of the reflection layer 15 is Rt, the light is radiated to the outside through the radiation path 17a. The emitted light and the light emitted directly from the phosphor layer 13 to the outside once proceed in the lower direction once, and the phosphor layer 1
3 is the sum of the light reflected near the boundary between the light emitting region and the non-light emitting region.

[0043]

(Equation 1) It is expressed as

Also, out of the total light amount, the emitted light reaching the filter layer 16 and the reflection layer 15 is:

[0045]

(Equation 2) It is expressed as

On the other hand, from the phosphor layer 13 side, the filter layer 16
The reflected light reflected by the reflection layer 15 after passing through the filter layer 16 passes through the filter layer 16 again, so that the reflectance of the combination of the filter layer 16 and the reflection layer 15 is represented by Rt · a ² . In addition, when the transmittance of the emitted light in the filter layer 16 is a and the above-described interlayer multiple reflection is taken into consideration, the emitted light emitted outside by the emission path 17b is

[0047]

(Equation 3) And the ratio (utilization rate) of the total light emission amount radiated to the outside is represented by the sum of Expression (1) and Expression (3).

[0048]

(Equation 4) Becomes

As described above, about half of the light emitted from the phosphor layer 13 passes through the filter layer 16 through the radiation path 17b, but the remaining light is directly emitted to the outside. However, the attenuation of the emitted light can be suppressed as compared with the related art in which the light passes through the filter layer 16. For example, Rp and Rt in the above equation (4) are general values (Rp = 0.3, Rt = 0.9) in a color PDP, and a =
If it is 0.7, the utilization rate of the total light emission amount is about 0.83, and it can be seen that about 83% of the total light emission amount is emitted to the outside.

That is, in the color PDP 1 of this embodiment, about half of the light emitted from the phosphor layer 13 is directly radiated to the outside, and the remaining half is attenuated by passing through the filter layer 16. There is a Japanese Patent Laid-Open No. 4-4764
Compared with a conventional example in which all emitted light passes through the filter layer 16 as disclosed in Japanese Patent Application Publication No. 0-104, a decrease in display luminance is suppressed, and display luminance can be maintained.

Next, referring to FIG. 3, a description will be given of an emission path through which external light, which is white light, incident from the front substrate 2 side, is reflected by the discharge cells 11 and emitted to the outside. FIG. 3 is an enlarged sectional view of the bottom surface of the discharge cell 11. Since the configuration is the same as that of FIG. 2, the description is omitted.

The external light is emitted to the outside through the following two paths, an emission path 18a and an emission path 18b. That is, the external light incident on the discharge cells 11 is reflected by the surface of the phosphor layer 13 and emitted to the outside through the emission path 18a.
The external light transmitted through the phosphor layer 13 is transmitted through the filter layer 16 and reflected by the reflection layer 15 through the emission path 18b, and then transmitted through the filter layer 16 again. The light is emitted to the outside while repeating inter-layer multiple reflection accompanied by transmission of the filter layer 16 with the surface.

Assuming that the total amount of incident external light is 1, the reflectance of the phosphor layer 13 is Rp, and the reflectance of the reflective layer 15 is Rt, the external light emitted to the outside through the emission path 18a is R
It is represented as p. Further, of the total light amount, the external light that passes through the phosphor layer 13 and reaches the filter layer 16 and the reflection layer 15 is:
It is represented as (1-Rp).

Here, the filter layer 16 has a transmittance of 100
Considering the case of using a% transparent filter, the outgoing path 1
External light emitted to the outside by 8b

[0055]

(Equation 5) And the total amount of external light reflected by the discharge cells 11 is Rp
And the sum of Equation (5),

[0056]

(Equation 6) Becomes

The filter layer 16 of the present embodiment has a red filter 16a, a green filter 16b, and a blue filter 16c.
The filter layer 16 and the reflective layer 1 are used.
If the reflectivity of the combination of the transparent filter and the reflective layer 15 is approximately １ ／ of the reflectivity of the combination of the transparent filter and the reflective layer 15, R
When t is replaced with Rt / 3, the color PDP of this embodiment
The total external light reflection at

[0058]

(Equation 7) It is expressed as

As described above, the reflectance Rp on the surface of the phosphor layer 13 in a general color PDP is about 0.3 and the reflectance Rt on the reflection layer 15 is 0.9 or more. Since the influence of the reflection on the reflection layer 15 is greater than the reflection on the surface of the layer 13, the absorption of unnecessary wavelength components of the external light in the emission path 18b can improve the contrast ratio under the external light. Connect. In the emission path 18b, of the wavelength components of the external light that is white light, only the same wavelength component as the emitted light passes through the filter layer 16, and other unnecessary wavelength components are absorbed. Further, the phosphor layer 13
Is transmitted through the filter layer 16 at least twice from the time when the light enters the filter layer 16 to the time when the light exits the filter layer 16, so that unnecessary wavelength components of the external light can be more reliably removed. .

Incidentally, Japanese Patent Laid-Open No. 4-4764 shown in FIG.
Since the reflectivity of the wavelength selective reflection layer 116 in the conventional example disclosed in Japanese Patent Publication No. 0 is expressed as Rt · a, the total output light amount of the emitted light in the conventional example is

[0061]

(Equation 8) It is expressed as

Further, if the reflectivity of the wavelength-selective reflective layer 116 is about の of the reflectivity of the combination of the transparent filter and the reflective layer 15, Rt in the equation (6) is calculated as Rt · (2
/ 3), the total external light reflection amount in this conventional example is

[0063]

(Equation 9) It is expressed as

As a result, the contrast ratio CRj under external light in the conventional example can be calculated from the equations (8) and (9).

[0065]

(Equation 10) It is expressed as

On the other hand, the contrast ratio CRh under external light in the present embodiment is obtained from the equations (4) and (7).

[0067]

[Equation 11] It is expressed as

The contrast ratio CRw under external light when a transparent filter is used is as follows:

[0069]

(Equation 12) Therefore, in Expression (10), Expression (11), and Expression (12),
Rp = 0.3, which is a general value of the color PDP described above.
Substituting Rt = 0.9 and a = 0.7, the value of equation (10) is 1.27, the value of equation (11) is 1.67, and the equation (12)
Is 1.05.

Comparing the above values, the contrast ratio of the present embodiment is about 1.6 times as compared with the example using the transparent filter, and the contrast ratio of the conventional example is compared with the example using the transparent filter. This means that the contrast ratio in the present embodiment is improved to about 1.32 times that of the conventional example.

As described above, in the present embodiment, the reflection layer 15
Since external light that is reflected by and exits outside passes through the filter layer 16 at least twice, the efficiency of absorbing unnecessary wavelength components of the external light is high. Therefore, even when the thickness of the two layers in which the reflection layer 15 and the filter layer 16 are combined is formed to be thinner than the thickness of the wavelength selection reflection layer 116 of the conventional example shown in FIG. Wavelength components can be further removed, and the contrast ratio under external light can be improved.

Accordingly, it is possible to achieve both the maintenance of the display luminance and the further improvement of the contrast ratio under external light, thereby realizing a good display quality.

Here, in order to confirm the effects of the present invention,
A color PDP without the reflective layer 15 (Comparative Panel 1), a color PDP without the filter layer 16 (Comparative Panel 2), and a color PDP without the reflective layer 15 and the filter layer 16 (Comparative Panel 3) are manufactured and compared. Was.

The display luminance was determined for the panel of the present invention and the comparative panel 1.
Showed almost the same luminance, and then, the comparative panel 2 and the comparative panel 3 showed good luminance in this order. Regarding the reflection of external light on the front surface of the panel when the panel is not allowed to emit light, the comparison panel 3 has the smallest reflection, the panel of the present invention and the comparison panel 2 have the next smallest reflection, and the comparison panel 1 has the largest reflection. Further, the color purity of the emission color was better in the panel of the present invention and the comparative panel 2 than the comparative panels 1 and 3. Comprehensively looking at the above results, the color PDP 1 of the present invention can improve the contrast ratio under external light and improve the color purity by suppressing the reflection of external light while maintaining the display luminance. It can be seen that the display characteristics are improved.

In the present embodiment, red, red, and red light correspond to the emission color of the phosphor layer 13 provided in each discharge cell 11.
Although the filter layers 16 of three colors of green and blue are provided, the filter layer 16 maintains the display luminance even if all three colors are not provided, for example, only two colors of red and blue. Thus, the contrast ratio under external light can be improved. Further, the reflectance of the phosphor layer 13 is Rp, and the reflectance of the emitted light by the combination of the filter layer 16 and the reflection layer 15 is Rp.
s (corresponding to the above-mentioned Rt · a ² ), also the filter layer 1
Assuming that the reflectance of external light due to the combination of the reflective layer 6 and the reflective layer 15 is Rw, the utilization rate L of emitted light and the reflectance C of external light are

[0076]

(Equation 13) It is expressed as

Rp is determined by the particle size and layer thickness of the phosphor, and Rs and Rw are determined by the material of the filter layer 16 and the reflective layer 15 and the layer thickness of the filter layer 16. Since the contrast ratio CR under external light is represented by L / C, it can be said that the CR value is improved by setting Rp and Rw as small as possible and Rs as large as possible. In particular, when Rp is large, the effect becomes extremely small even if a good filter is used. Here, FIGS. 4 to 6 show the results of evaluating how much the contrast ratio under external light has been improved as compared with the case where Rs = Rw = 1.

FIG. 4 shows that Rs = 0.441 (Rt = 0.
FIG. 9 is an evaluation result diagram showing the Rp dependency of the contrast ratio CR under external light when 9, a = 0.7) and Rw = 0.45.

Phosphor layer 13 provided in discharge cell 11
If the layer is too thick, the reflection of external light on the surface of the phosphor layer 13 increases, and the contrast ratio decreases. Therefore, as shown in FIG. 4, when the thickness of the phosphor layer 13 is set such that the external light reflectance of the phosphor layer 13 alone on the surface of the phosphor layer 13 becomes 50%, the contrast ratio becomes about 50%. It turns out that it improves by 1.4 times. Therefore, the phosphor layer 13
50% of external light reflectance of the phosphor layer 13 alone on the surface
By setting as follows, the contrast ratio under external light is significantly improved, and the effect of the present invention can be further improved.

The dotted line shown in FIG. 4 shows the dependence of the contrast ratio CR on Rp when the filter layer 16 is not used. It can also be seen that the contrast ratio cannot be improved. This result indicates that the influence of the reflection of the external light on the combination of the filter layer 16 and the reflection layer 15 is greater than the reflection on the surface of the phosphor layer 13.

FIG. 5 is an evaluation result diagram showing the Rs dependence of the contrast ratio CR under external light when Rp = 0.3 and Rw = 0.45. FIG. Rs = 0.
FIG. 10 is an evaluation result diagram showing the Rw dependency of the contrast ratio CR under external light at the time of 5.

From FIG. 5, when Rs = 0.7, the contrast ratio is improved by about 1.6 times, and from FIG. 6, Rw =
It can be seen that the contrast ratio is improved about 1.6 times at 0.3. Therefore, the filter layer 16 and the reflection layer 15
The reflectivity due to the combination of is that in the process in which emitted light and external light are transmitted through the filter layer 16 and reflected by the reflective layer 15,
Rs ≧ 0.7 (the reflectance of the same wavelength component as the emitted light is 70%
The contrast ratio is improved by at least 1.6 times or more by setting Rw ≦ 0.3 (the reflectance of unnecessary wavelength components other than the former is 30% or less). It is possible to further achieve both the maintenance of the luminance and the improvement of the contrast ratio under external light, and accordingly, the color purity of the display color can be improved.

In this embodiment, an inorganic pigment powder such as titanium oxide is used for the reflection layer 15. However, even if a metal powder or a metal film is used, external light that is white light is reflected. be able to. An inorganic pigment powder may be mixed with the metal powder, and if the address electrode 12 itself is used as a metal film, it is not necessary to separately provide the reflective layer 15, and the manufacturing of the back substrate 3 can be simplified. Further, an inorganic pigment powder may be mixed into the material of the rear substrate glass 9 and the partition 10 so that the rear substrate glass 9 and the partition 10 themselves also have the function of the reflection layer 15.

Although the present embodiment has been described using an AC-driven surface type plasma display panel, the light emitted from the phosphor layer 13 on the back substrate 3 is applied to the DC-driven surface type or counter discharge type. With a so-called reflective structure viewed through the front substrate 2, the effects of the present invention can be obtained in the same manner as described above.

[0085]

According to the color plasma display panel of the present invention, a white reflective layer for reflecting all visible light wavelengths is provided between the bottom surface of the discharge cell and the phosphor layer, and light emitted from the phosphor layer. Since a filter layer that efficiently transmits only the wavelength component is provided, the display luminance can be maintained and the contrast ratio under external light can be further improved, and good display quality can be realized.

Further, by setting the thickness of the phosphor layer such that the white light reflectance of the phosphor layer alone on the surface of the phosphor layer becomes 50% or less, the contrast ratio under external light is reduced. Can be further improved.

Further, the reflectivity of the combination of the filter layer and the reflective layer is set to 70% of the reflectivity of the same wavelength component as the emitted light.
% Or more, and the reflectance of wavelength components other than the wavelength component of the emitted light is set to be 30% or less, so that both the maintenance of the display luminance and the improvement of the contrast ratio under external light can be further achieved. Accordingly, the color purity of the display color can be improved.

When the address electrode provided on the rear substrate is used as a metal film for forming the reflection layer, it is not necessary to separately provide a reflection layer, and the production of the rear substrate can be simplified.

[Brief description of the drawings]

FIG. 1 is a partial sectional view of a first embodiment of a color plasma display panel of the present invention.

FIG. 2 is an enlarged sectional view of a bottom surface portion and a front substrate of the discharge cell shown in FIG.

FIG. 3 is an enlarged sectional view of a bottom surface portion and a front substrate of the discharge cell shown in FIG.

FIG. 4 is an evaluation result diagram showing the Rp dependency of the contrast ratio CR under external light.

FIG. 5 is an evaluation result diagram showing the Rs dependency of the contrast ratio CR under external light.

FIG. 6 is an evaluation result diagram showing the Rw dependency of the contrast ratio CR under external light.

FIG. 7 is a partial cross-sectional view of an example of a conventional color plasma display panel.

8 is a partial perspective view showing a configuration of the color plasma display panel shown in FIG.

9 is a partial cross-sectional view of an example in which the display brightness of the color plasma display panel shown in FIG. 7 is improved.

10 is a partial cross-sectional view of an example in which the contrast ratio of the color plasma display panel shown in FIG. 7 is improved.

11 is a partial sectional view of an example in which the contrast ratio of the color plasma display panel shown in FIG. 7 is improved.

FIG. 12 is a partial cross-sectional view of another example of a conventional color plasma display panel.

FIG. 13 is a partial sectional view of still another example of the conventional color plasma display panel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Color plasma display panel 2 Front substrate 3 Rear substrate 4 Discharge space 5 Front substrate glass 6 Sustain electrode 6a Transparent electrode 6b Bus electrode 7 Dielectric layer 8 Protective layer 9 Rear substrate glass 10 Partition 10a Front partition 10b Rear partition 11b Cell 12 Address electrode 13 Phosphor layer 13a Red phosphor layer 13b Green phosphor layer 13c Blue phosphor layer 14 Mixed gas 15 Reflective layer 16 Filter layer 16a Red filter 16b Green filter 16c Blue filter 17a Radiation path 17b Radiation path 18a Emission path 18b Outgoing path

Claims (7)

(57) [Claims] 1. A front substrate for displaying an image, and a rear substrate facing the front substrate. A large number of partition walls and address electrodes are alternately arranged on a surface of the rear substrate facing the front substrate. By being provided, a discharge cell serving as a unit for generating plasma discharge is formed in a region partitioned by the partition, and a color plasma display panel in which a phosphor layer is provided on at least a bottom surface portion of the discharge cell, Between the bottom surface portion of the discharge cell and the phosphor layer, a white reflective layer that reflects all visible light wavelengths, and furthermore, a light emitting light generated from the phosphor layer on the reflective layer. A color plasma display panel, comprising: a filter layer that transmits a wavelength component. 2. The phosphor layer according to claim 1, wherein the thickness of the phosphor layer is such that the reflectance of white light on the surface of the phosphor layer of the phosphor layer alone is 50% or less. Color plasma display panel. 3. The reflectivity of the combination of the filter layer and the reflection layer is the same as the wavelength of the emitted light in the process in which light transmitted through the phosphor layer is transmitted through the filter layer and reflected by the reflection layer. 3. The color plasma display panel according to claim 1, wherein the reflectance of the component is 70% or more, and the reflectance of a wavelength component other than the wavelength component of the emitted light is 30% or less. 4. The color plasma display panel according to claim 1, wherein the reflection layer is formed of an inorganic pigment powder. 5. The color plasma display panel according to claim 1, wherein the reflection layer is formed of a metal powder. 6. The color plasma display panel according to claim 1, wherein said reflection layer is formed of a metal film. 7. The color plasma display panel according to claim 6, wherein said metal film is an address electrode provided on a surface of said rear substrate.