JP2003100222A - Plasma display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a plasma display panel having high contrast, high image quality and high resolution by reducing reflected light from a discharge cell and also making sure of useful brightness. SOLUTION: In this plasma display panel, plural barrier ribs 10 are disposed between substrates arranged in face-to-face relation with each other, and plural shade layers 4 are formed on the one of the substrates in perpendicular direction to the barrier ribs 10, and a discharge cell is formed in a region 18 demarcated with adjacent barrier ribs 10 and adjacent shade layers 4. Here, a shade body (a bus electrode 14b) is formed in a region with higher intensity of the reflected light when viewing the light incident from outside of a panel and reflected on the inside of a discharge cell from the perpendicular direction to the panel.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma display panel used for an image display device such as a computer and a television.

[0002]

2. Description of the Related Art A conventional plasma display panel (hereinafter referred to as "panel") generally has a structure as shown in FIG.

As shown in FIG. 7, on the front substrate 1, a plurality of stripe-shaped discharge electrode pairs forming a pair of the scan electrodes 2 and the sustain electrodes 3 are formed, and adjacent discharge electrode pairs on the front substrate 1 are formed. A light-shielding layer (black stripe) 4 is formed between them. The scan electrodes 2 and the sustain electrodes 3 are transparent electrodes 2a and 3a and transparent electrodes 2a and 3a, respectively.
And bus electrodes 2b and 3b made of silver or the like electrically connected to each other. The bus electrodes 2b and 3b are arranged at the ends of the transparent electrodes 2a and 3a on the side of the light shielding layer 4, respectively. A dielectric layer 5 made of lead glass or the like is formed on the front substrate 1 so as to cover the discharge electrode pair and the light shielding layer 4, and a magnesium oxide (MgO) vapor deposition film or the like is formed on the dielectric layer 5. The protective film 6 is formed.

A plurality of stripe-shaped data electrodes 9 covered with an insulating layer 8 made of lead glass or the like are formed on a rear substrate 7 which faces the front substrate 1.
The data electrode 9 is formed on the insulator layer 8 between the data electrodes 9.
A plurality of stripe-shaped barrier ribs 10 are arranged in parallel with, and a phosphor layer 11 is provided on the side surface between the barrier ribs 10 and on the surface of the insulator layer 8.

The front substrate 1 and the rear substrate 7 are arranged so as to face each other across the discharge space so that the scan electrodes 2 and the sustain electrodes 3 and the data electrodes 9 are orthogonal to each other, and the periphery thereof is sealed. The discharge space is filled with a mixed gas of neon (Ne) and xenon (Xe) as a discharge gas. Further, the discharge space is partitioned into a plurality of sections by partition walls 10, and discharge cells are formed at the intersections of the discharge electrode pairs and the data electrodes 9. The discharge cells are red, green and blue. Thus, the phosphor layers 11 are sequentially arranged for each color. By applying a voltage between the scan electrode 2 and the sustain electrode 3 forming the discharge electrode pair, the ultraviolet rays emitted by the discharge generated in each discharge cell excite the phosphor layer 11 to emit display light. It is generated and the image is displayed.

[0006]

However, in the above-mentioned conventional structure, since the partition wall 10 and the phosphor layer 11 formed on the rear substrate 7 are white, there is much external light reflection and the contrast ratio is lowered. Had. Also, when displaying black, the brightness due to external light reflection is high, so CR
Compared to T, black was close to gray when displaying an image. Therefore, no matter how much the peak brightness is increased to improve the contrast ratio, when a video source such as a movie where there are many dark scenes is displayed, the color of the dark portion appears to appear whitish.

In order to improve this, the contrast ratio can be improved by disposing a neutral density filter on the front surface of the panel to reduce the external light entering the panel. In that case, the contrast ratio from the phosphor layer 11 is increased. Since the display light emission is also attenuated and the display brightness is lowered, the transmittance of the neutral density filter cannot be reduced so much. Further, when a color filter having the same color as the display color of the phosphor layer 11 is provided on each discharge cell of the front substrate 1, the contrast margin and the color purity of the display color are improved. As a result, the yield decreases. Further, the contrast ratio can be improved by increasing the area ratio of the light-shielding layer 4 occupying one discharge cell, but in that case, the aperture ratio of the discharge cell is lowered and the display brightness is also lowered, which is practical. It is difficult to improve only the contrast ratio while maintaining the brightness.

The present invention has been made to solve such a problem, and by reducing the reflected light of the discharge cell and ensuring a practical brightness, high image quality and high definition with a high contrast ratio can be obtained. The purpose is to realize a plasma display panel.

[0009]

In order to achieve this object, a plasma display panel of the present invention has a plurality of partition walls provided between opposed substrates, and one of the substrates is arranged in a direction perpendicular to the partition walls. In a plasma display panel in which a plurality of light-shielding layers are provided and discharge cells are formed in a region defined by the adjacent barrier ribs and the adjacent light-shielding layers, external light incident on the discharge cells from outside the panel is generated. When the reflected light reflected in the discharge cells is viewed from the vertical direction of the panel, a light shield is provided in a region where the intensity of the reflected light is high. With this configuration, the intensity of reflected light can be reduced.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings of FIGS. The same parts as those shown in FIG. 7 are designated by the same reference numerals.

(First Embodiment) The difference between the panel according to the first embodiment of the present invention and the conventional panel shown in FIG. 7 lies in the formation positions of the bus electrodes forming the scan electrodes and the sustain electrodes. . 1 and 2 are schematic plan views showing the positional relationship among the scan electrodes, the sustain electrodes, the partition walls, and the light shielding layers in the panel according to the first embodiment.

As shown in FIG. 1, scan electrodes 13 and sustain electrodes 14 arranged with a discharge gap 12 therebetween are transparent electrodes 13a and 14a and bus electrodes 13b and 1b, respectively.
4b, the bus electrode 13b is arranged on the transparent electrode 13a on the light shielding layer 4 side, and the bus electrode 14b is arranged on the transparent electrode 14a on the discharge gap 12 side. The bus electrode 13b is provided on the transparent electrode 13a on the discharge gap 12 side to form the scanning electrode 13, and the bus electrode 14b is provided.
Is provided on the light-shielding layer 4 side on the transparent electrode 14a, and the sustain electrode 14
May be configured.

Further, as shown in FIG. 2, the bus electrode 14
b and 15b are disposed on the discharge gap 12 side on the transparent electrodes 14a and 15a, respectively, and the sustain electrode 14 and the scan electrode 1 are provided.
5 are configured. 1 and 2, the bus electrodes 13b, 14b, 15b are hatched.

The front substrate 1 on which the scan electrodes 13 (or the scan electrodes 15) and the sustain electrodes 14 having the above structure are formed and the rear substrate 7 on which a predetermined member similar to the conventional panel is formed are opposed to each other. A panel is constructed by placing and sealing the periphery. The discharge space formed between the front substrate 1 and the rear substrate 7 is filled with a mixed gas containing Xe (for example, a mixed gas of Ne and Xe) at a pressure of about 200 to 500 Torr. Further, the discharge space is partitioned into a plurality of sections by the partition wall 10, and the scanning electrode 13 (or the scanning electrode 1) is divided.
A discharge cell is formed at the intersection of the discharge electrode pair consisting of 5) and the sustain electrode 14 and the data electrode 9. That is, the discharge cell has a region 1 indicated by a one-dot chain line in FIGS.
8 and this region is defined by the adjacent barrier ribs 10 and the adjacent light shielding layer 4. Then, in each discharge cell, the phosphor layer 11 is provided so as to be red, green and blue.
Are sequentially arranged one by one.

Next, a method for driving this panel will be described with reference to FIGS. 3 and 4. FIG. 3 is a block conceptual diagram of a plasma display device using the panel of the present invention, and FIG. 4 is a waveform diagram showing an example of a drive waveform applied to each electrode of the panel.

As shown in FIG. 3, the electrode array of the panel body has a matrix structure of discharge cells of M rows × N columns, and M rows of scanning electrodes 13 or scanning electrodes 15 (symbol SC) are arranged in the row direction. ₁ to SC expressed by _M) and sustain electrodes 14
(Represented by symbols SU _{1 to} SU _M ) are arranged, and N is arranged in the column direction.
Data electrodes 9 (represented by symbols D _{1 to} D _N ) in columns are arranged. Scan electrodes SC _{1 to} SC _M and sustain electrodes SU _{1 to} S
U _M is driven by the scan electrode driving device and the sustain electrode driving device, and the data electrodes D _{1 to DN} are driven by the data electrode driving device.

Next, the display operation of this panel will be described. When displaying a TV image, the image is composed of 60 fields per second in the NTSC system. When an image is displayed on the panel, the number of light emission pulses having a certain intensity is set to, for example, 1, 2, 4, 8, 16, 32, 6
Eight subfields such as 4 and 128 are binary weighted to form one field, and a combination thereof represents an intermediate color. 8 for 1 field
When configured with one subfield, each color of red (R), green (G), and blue (B) can express 256 gradations, and a display of about 16.77 million colors can be performed.

Further, the number of subfields is increased to further improve the image quality, and a plurality of weighting combinations of subfields for displaying gradations are used to generate a pseudo contour generated by the movement of the line of sight when displaying a moving image. Is used.

FIG. 4 shows a drive waveform of the panel in one subfield, and the subfield is composed of an initialization period, a writing period, a sustaining period and an erasing period.

As shown in FIG. 4, an initializing pulse is applied to the scan electrodes SC ₁ -SC _M in the initializing period to initialize the wall charges in the discharge cells. Next, in the writing period,
Data electrodes D _{1 to} D _N corresponding to discharge cells for displaying while applying a scan pulse to the _first scan electrode SC _1.
A write pulse is applied to write discharge to cause wall charges to accumulate on the surface of the dielectric layer 5. Second scan electrode S
A scan pulse is applied to C ₂ , and a write pulse is applied to the data electrodes D _{1 to} D _N corresponding to the discharge cells for display to cause a write discharge and accumulate wall charges on the surface of the dielectric layer 5. Since similarly sequentially scans the scanning electrodes SC ₃ to SC _M, writes the image information for one screen by accumulating wall charges on the dielectric layer 5 surface of the discharge cell to be displayed.

Next, in the sustain period, in order to perform sustain discharge, the data electrodes D _{1 to DN} are grounded, and sustain pulses are alternately applied to all scan electrodes SC _{1 to} SC _M and sustain electrodes SU _{1 to} SU _M. By applying, the sustain discharge is generated in the discharge cell (the discharge cell in which the image information is written) in which the wall charge is accumulated on the surface of the dielectric layer 5, and the discharge is maintained while the sustain pulse is applied. In the subsequent erase period, the erase is performed for an incomplete discharge is extinguished generated wall charges by applying a narrow erase pulse width to the sustain electrodes SU ₁ to SU _M.

Next, the result of measuring the reflection brightness by the external light (external light reflection brightness) using the panel according to the first embodiment will be described. In the measurement, an electrode in which each type of electrode shown in FIG. 1 and FIG. 2 was divided into two areas and formed in one panel was used. Here, the pixel pitch P is 1 mm, the width L of the transparent electrodes 13a, 14a, 15a is 360 μm, the width We of the bus electrodes 13b, 14b, 15b is 80 μm, and the width Wbs of the light shielding layer 4 is 100 μm. Further, the distance de from the center of the discharge cell to the center line of the bus electrode arranged at the center of the discharge cell was 100 μm. Table 1 shows the results of measuring the external light reflection luminance when the illuminating device was arranged at an angle of 45 ° above the surface of this panel and the vertical illuminance on the panel surface was 150 lx.

[0023]

[Table 1]

In Table 1, Example 1 is an electrode of the type shown in FIG. 1, and Example 2 is an electrode of the type shown in FIG. Further, as shown in FIG. 7, the conventional example is a conventional panel in which the bus electrodes 2b and 3b are arranged on the outer ends (on the side of the light shielding layer 4) on the transparent electrodes 2a and 3a, that is, the end portions of the discharge cells. Is. The external light reflection brightness is shown as a relative value with the external light reflection brightness of the conventional example being 1.

As is apparent from Table 1, the bus electrode 14b
On the transparent electrode 14a on the center side (on the side of the discharge gap 12)
The external light reflection luminance of the panel of Example 1 in which the bus electrode 13b is disposed on the transparent electrode 13a on the outer end side (on the side of the light shielding layer 4) is lower than that of the conventional panel. Recognize. In addition, the external light reflection luminance of the panel of Example 2 in which the bus electrodes 14b and 15b are arranged at the ends of the transparent electrodes 14a and 15a on the central portion side, that is, near the central portion of the discharge cell is the same as that of the panel of Example 1. The brightness is lower than the external light reflection brightness, which is about 10% lower than that of the conventional panel.

Generally, it is known that a phosphor used in a plasma display panel has a scattering characteristic for visible light which is close to Lambertian scattering. Therefore, most of the light such as indoor illumination light that obliquely enters the discharge cell from the outside of the panel is scattered and reflected on the surface of the phosphor layer 11, and part of the light is transmitted to the back surface of the panel. This phosphor layer 11
The light scattered on the surface is diffused in a hemispherical shape with respect to the scattering surface, most of it is directly extracted to the outside of the panel, and part of it is incident on the phosphor layer 11 or the like on the side surface of the partition wall 10 and further scattered. It is thought that multiple scattering is repeated. Therefore, when the external light incident on the discharge cell is extracted to the outside of the panel, the distribution of the external light reflection luminance viewed from the vertical direction of the panel is the central portion of the discharge cell (the central portion between the light shielding layers 4). The distribution characteristic of the mountain shape becomes higher at.

Further, the light shielding layer 4 and the bus electrodes 13b, 14
The opaque portions such as b and 15b serve as a light shield when external light is incident on the discharge cell, the shade of which is reflected on the surface of the phosphor layer 11 in the discharge cell, and the external light incident from the opening is inside the discharge cell. Will be scattered. By disposing the bus electrodes 14b and 15b in the central portion of the discharge cell (the central portion between the light shielding layers 4), it is possible to shade the bus electrodes 14b and 15b near the central portion of the discharge cell as compared with the conventional panel. It is thought that the reflected light could be reduced by the shadow.

FIG. 5 shows that the light shielding layer 4 prevents external light from entering the discharge cell from obliquely above the panel having the electrode arrangement shown in FIG.
Alternatively, it is a cross-sectional view schematically showing a shadow that is blocked by the bus electrodes 14 b and 15 b and dropped on the surface of the phosphor layer 11. In FIG. 5, the transparent electrodes 14a and 15a are shown with hatching omitted, and the broken line arrow represents the external light incident on the discharge cell. Further, when viewed from the vertical direction of the panel, a region where the light shielding layer 4 or the bus electrodes 14b and 15b exist is shown as a region A, and the light shielding layer 4 or the bus electrode 1 is shown.
Regions 4b and 15b which are shaded on the surface of the phosphor layer 11 are shown as regions B. This area A and area B
Is an area where the external light reflection brightness is low.

Referring to FIG. 5, the bus electrode 1
Considering the case where 4b and 15b are provided close to the light-shielding layer 4 side, when viewed from the vertical direction of the panel, it is better to place the bus electrodes closer to the central portion than to the end portions of the discharge cells.
It can be seen that the area A and the area B are less overlapped and the area A and the area B are closer to the central portion of the discharge cell, so that the external light reflection luminance is reduced.

From the above, when the external light incident on the discharge cell from the outside of the panel is reflected in the discharge cell as viewed from the vertical direction of the panel, as in the discharge cell structure in the first embodiment. By disposing the bus electrodes (light shields) 14b and 15b in the region where the intensity of the reflected light is high, the reflected light in the high intensity portion is blocked, and the contrast ratio is maintained without changing the discharge characteristics of the discharge cell. It is feasible to improve

In the first embodiment, the width We of the bus electrodes 13b, 14b, 15b is set to 80 μm, and the distance de from the center of the discharge cell to the center line of the bus electrodes 13b, 14b, 15b is set to 100 μm. However, We is 20 μm ≦ We ≦ 100 μm and de is 5
Similar effects can be obtained even in the range of 0 μm ≦ de ≦ 330 μm. The upper limit of the preferable range of de depends on the pixel pitch P, and is 50 μm ≦ de ≦ P /
When it is 3, the contrast ratio can be improved, and more preferably 50 μm ≦ de ≦ P / 6.

Further, in the first embodiment, the light shielding layer 4
However, the width Wbs is not limited to this, and the width Wbs is not limited to this. By decreasing Wbs by the ratio of the brightness of the bright place decreased by decreasing de, light emission during display is achieved even with the same contrast. The brightness can be improved.

(Embodiment 2) FIG. 6 is a schematic plan view showing the positional relationship among the scan electrodes, sustain electrodes, partition walls and light-shielding layers in the panel of Embodiment 2 in the area indicated by the alternate long and short dash line. Reference numeral 18 indicates a region of one discharge cell. The difference from the panel of the first embodiment is that the electrode 16 and the electrode 17 are arranged and formed so that two discharge gaps are formed in each discharge cell, and the electrode 16 is composed of a transparent electrode 16a and a bus electrode 16b. At the same time, the bus electrode 16b is arranged near the center of the discharge cell, and the electrode 17 made of metal is arranged at the outer end of the discharge cell. A discharge gap is formed between the electrode 16 and the electrode 17,
Discharge for display is performed by 6 and the electrode 17.

When the external light reflection brightness in the case of the conventional panel is 1, the relative value of the external light reflection brightness in the panel of the second embodiment is 0.87, and the bright place contrast is 84. Therefore, in the panel of the second embodiment, compared with the conventional panel and the panel of the first embodiment, the external light reflection luminance is lowered and the bright place contrast is improved. here,
Pixel pitch P = 1 mm, bus electrode 16b width We = 40
The width Wbs of the light-shielding layer 4 was 100 μm. Also,
The distance de from the center of the discharge cell to the center line of the bus electrode 16b was de = 60 μm, and the width of the electrode 17 was 40 μm, which was the same as the width of the bus electrode 16b.

Generally, in a surface discharge AC type panel, the emission brightness in the discharge cell is highest near the discharge gap,
It decreases as the distance from the discharge gap increases.

On the other hand, when the external light incident from the outside of the discharge cell is reflected inside the discharge cell, the light is scattered on the surface of the phosphor layer 11 and halation due to multiple reflections among the respective components causes diagonally upward movement of the panel. When the external light that has entered through the discharge opening exits from the discharge cell, the brightness is highest near the center of the discharge cell, and the reflected brightness decreases toward the end of the discharge cell.

In the electrode structure of the first embodiment, the discharge gap 12 is located in the center of the discharge cell, and the maximum portion of the emission luminance distribution due to discharge is in the center of the discharge cell. Further, the maximum portion of the external light reflection luminance distribution is also the central portion of the discharge cell, and the maximum portion of the light emission luminance distribution due to the discharge and the maximum portion of the external light reflection luminance distribution overlap. Therefore, although the external electrode reflection brightness can be reduced by disposing the bus electrode in the center of the discharge cell, at the same time, high-luminance light emission due to discharge is also blocked.

Therefore, in the panel of the second embodiment, the bus electrode 16b is provided in the vicinity of the central portion of the discharge cell having high external light reflection brightness.
By arranging the (light-shielding body) to block the reflected light, and by disposing the discharge gap with high emission brightness at a position away from the bus electrode 16b, a panel with high contrast in bright place and high image quality with high brightness can be obtained. Can be realized.

In the second embodiment, two discharge gaps are formed in each discharge cell forming a pixel,
Although the bus electrode 16b is arranged at the center of the discharge cell and the electrode 17 is arranged at the outer end of the discharge cell, the same effect can be obtained by disposing a black stripe as a light shield at the center of the discharge cell. Is obtained. Further, even when three or more discharge gaps are provided in one discharge cell, the discharge gaps may be arranged at positions apart from the light shield.

In the second embodiment, the width We of the center bus electrode 16b is 40 μm and the distance de from the center of the discharge cell to the center line of the bus electrode 16b is de = 60 μm, but We is 20 μm ≦ We. ≦ 100 μm, de is 5
Similar effects can be obtained even in the range of 0 μm ≦ de ≦ 330 μm. The upper limit of the preferable range of de varies depending on the pixel pitch P. When 50 μm ≦ de ≦ P / 3, the contrast ratio can be improved, and more preferably 50 μm ≦ de ≦ P / 6.

Further, in the second embodiment, the light shielding layer 4
The width Wbs was set to 100 μm, but the width Wbs is not limited to this. By decreasing Wbs by the ratio of the brightness in the bright place, which is decreased by decreasing de, light emission at the time of display can be achieved even with the same contrast. The brightness can be improved.

[0042]

As described above, according to the present invention, it is possible to reduce the reflection brightness due to the reflected light by the external light incident from the outside of the panel, improve the contrast in the bright place, and have the high brightness and high image quality. It is possible to realize an excellent plasma display panel.

[Brief description of drawings]

FIG. 1 is a schematic plan view showing a plasma display panel according to a first embodiment of the present invention so that a positional relationship among a scan electrode, a sustain electrode, a partition and a light shielding layer can be seen.

FIG. 2 is a schematic plan view showing another example of the plasma display panel according to the first embodiment of the present invention so that the positional relationship among the scan electrodes, the sustain electrodes, the partition walls and the light shielding layer can be seen.

FIG. 3 is a block diagram of a drive circuit of an image display device using the plasma display panel of the present invention.

FIG. 4 is a timing chart of a driving method of the plasma display panel of the present invention.

FIG. 5 is a cross-sectional view schematically showing the shade generated on the surface of the phosphor layer by the light shielding layer and the bus electrode in the plasma display panel according to the first embodiment of the present invention.

FIG. 6 is a schematic plan view showing a plasma display panel according to a second embodiment of the present invention so that a positional relationship among a scan electrode, a sustain electrode, a partition and a light shielding layer can be understood.

FIG. 7 is a perspective view showing a main part of a conventional plasma display panel.

[Explanation of symbols]

1 Front substrate 2, 13, 15 scanning electrodes 3, 14 Sustain electrode 4 Light-shielding layer 5 Dielectric layer 6 protective film 7 Back substrate 8 Insulator layer 9 Data electrode 10 partitions 11 Phosphor layer 12 discharge gap 16, 17 electrodes

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Junpei Hashiguchi             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 5C040 FA01 FA04 GB03 GB14 GC02                       GC05 LA05 LA10 MA04                 5C058 AA11 AB06 BA08

Claims (6)

[Claims] 1. A plurality of partition walls are provided between opposed substrates, and a plurality of light shielding layers are provided on one of the substrates in a direction perpendicular to the partition walls, and the adjacent partition walls and the light shielding layer adjacent to each other. In a plasma display panel in which discharge cells are formed in a region defined by, when external light incident on the discharge cells from outside the panel is viewed in the vertical direction of the panel as reflected light reflected in the discharge cells, A plasma display panel characterized in that a light-shielding member is provided in a region where the intensity of the reflected light is high. 2. The plasma display panel according to claim 1, wherein the light shield is provided in a central portion between the light shield layers. 3. A pair of electrodes, which are arranged with a discharge gap, are formed between the light-shielding layers on the substrate provided with the light-shielding layer, and the electrodes are composed of a transparent electrode and a metal electrode as a light-shielding body. The plasma display panel according to claim 1, wherein the metal electrode constituting at least one of the paired electrodes is formed on the transparent electrode on the discharge gap side. 4. The plurality of electrodes are formed so that a plurality of discharge gaps are formed between the light shielding layers on the substrate, and the plurality of discharge gaps are provided separately from the light shield. Plasma display panel according to. 5. The width We of the metal electrode is 20 μm ≦ We ≦
The plasma display panel according to claim 3, wherein the plasma display panel has a thickness of 100 μm. 6. The plasma display panel according to claim 3, wherein the distance de from the center of the discharge cell to the center line of the metal electrode is 50 μm ≦ de ≦ 330 μm.