Display device

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a display device such as a plasma display panel (hereinafter also referred to as PDP), and more particularly to a display device in which color split (or color separation) is difficult to occur and which presents less graininess in images.

2. Description of the Background Art

Trio- (or stripe-) arrangement pixels and delta-arrangement pixels exemplify matrix type displays having pixels arranged in a matrix form.

FIGS. 19 and 20

are schematic plan views showing a conventional trio-arrangement pixel PT and a conventional delta-arrangement pixel PD, respectively. Although each including three subpixels (or cells) C for emitting the three primary colors of light, red (R), green (G) and blue (B), respectively, these pixels differ from each other in arrangement of the subpixels C. A subpixel for emitting red, for example, is hereinafter also referred to as “red subpixel”.

For ease of comparison, both of the trio-arrangement pixels PT and the delta-arrangement pixels PD respectively adjacent to each other in first and second (in this case, vertical and horizontal) directions v and h are spaced at an equal arrangement interval (hereinafter also briefly referred to as “interval”) (the arrangement interval is indicated by p) or at an equal interval between pixel centers, respectively. The arrangement interval may be different in the first and second directions v and h. The subpixels C included in both of the pixels PD and PT have the same shape and area, each of which is rectangular with dimensions of (p/2) and (p/3) in the first and second directions v and h, respectively.

As shown in

FIG. 19

, in a display device

100

T having the trio-arrangement pixels PT, red, green and blue subpixels C are arranged in this order in the second direction h, and subpixels C for the same luminous color are arranged in the first direction v. Particularly, components of the interval between adjacent subpixels C in the display device

100

T are p and (p/3) in the first and second directions v and h, respectively. In this case, subpixels C in each pixel PT are aligned in a row in the second direction h, and pixels PT adjacent to each other either in the first or second direction v or h have the same subpixel arrangement.

On the other hand, as shown in

FIG. 20

, the red, green and blue subpixels C are arranged in the form of a delta (Δ) in each pixel PD. In the whole display of a display device

100

D having delta-arrangement pixels PD, the red, blue and green subpixels C are arranged in this order in the second direction h, and subpixels C for the same luminous color are arranged in the first direction v. Particularly, components of the interval between adjacent subpixels C in the display device

100

D are (p/2) and (p/3) in the first and second directions v and h, respectively.

In each delta-arrangement pixel PD, a subpixel C (for green, in this case) present singly in the second direction h is called “single subpixel” and two subpixels C (for red and blue, in this case) aligned adjacently in the second direction h are called “paired subpixels”. It is possible to consider that the single subpixel C and the paired subpixels C are arranged alternately at an interval of (p/2) in the first direction v.

In the whole display of the display device

100

D, pixels PD having the same subpixel arrangement are arranged adjacently in the first direction v. In the second direction h, two types of pixels PD are aligned alternately in which the single subpixel C and the paired subpixels C are arranged in reversed positions to each other in the first direction v.

In general, trio-arrangement pixels PT have good linearity both in the first and second directions v and h in spite of low resolution for the number of pixels, which are thus suitable for figure drawing. On the other hand, delta-arrangement pixels PD, whose adjacent subpixels C are spaced at an interval of (p/2) in the first direction v, generally have high resolution for the number of pixels, whereas being inferior to the pixels PT in linearity both in the first and second directions v and h. Since the pixels PT and PD both have advantages and disadvantages in display quality as described above, either of them is selected generally depending on images to be displayed or personal preference.

Japanese Patent Application Laid-Open No. 2000-357463, for example, discloses a basic configuration as an example of application of delta-arrangement pixels PD to a plasma display panel (PDP).

Further, as one application of such configuration, Japanese Patent Application Laid-Open No. 2000-298451 discloses a method of driving two data electrodes (W electrode) in common (hereinafter also referred to as “W electrode common address driving method”). With this method, circuit costs can be reduced.

As another application, Japanese Patent Application Laid-Open No. 2001-135242 discloses a method of distributing sustain discharge current paths (hereinafter also referred to as “current distributing method”). With this method, a peak current value in discharge current can be reduced, resulting in reduced circuit costs.

As described above, applications of delta-arrangement pixels PD to a PDP create the above-described various advantages which are not attainable by trio-arrangement pixels PT.

However, conventional delta-arrangement pixels PD have a problem of visibility in that “color split (or color separation)” easily occurs as compared to conventional trio-arrangement pixels PT.

The narrowest visual angle that a man of visual acuity of 1.0 can resolve is one minute angle. In a display device such as a PDP or CRT, one pixel is divided into three subpixels in area, to which the three primary colors, red, green and blue are assigned, respectively. These three subpixels are simultaneously illuminated, to thereby display white. However, when a visual angle between subpixels exceeds one minute angle, an observer sees the three colors splittingly (or separately) and becomes incapable of recognizing one pixel as white. Such phenomenon that the colors are seen splittingly (or separately) is called “color split (or color separation)”. This color split depends on an observation distance and may become more significant as a display (therefore, a pixel) is observed from a nearer position.

The visual angle between subpixels C is assumed to be equal to the arrangement interval between the subpixels C when viewed from the same distance. Regardless of whether in the same pixel or between adjacent pixels, a minimum value of the interval between the subpixels C for the respective luminous colors (or distance between pixel centers) greatly affects color split. As shown in

FIG. 19

, in each pixel PT, the minimum value of the interval between the subpixels C (or the minimum value of the distance between the pixel centers) is 0.33 p. On the other hand, as shown in

FIG. 20

, the above minimum value is 0.6 p in each pixel PD. Accordingly, the minimum value between the pixel centers of the subpixels C in the pixels PD is substantially twice that in the pixels PT. Thus, color split easily occurs in the pixels PD as compared to the pixels PT.

Further, the conventional delta-arrangement pixels PD have another problem of visibility of presenting “graininess” more than in the conventional trio-arrangement pixels PT. This phenomenon easily occurs when black layers are provided in non-display areas NC (see

FIGS. 19 and 20

) between the subpixels C.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a display device in which color split is difficult to occur and which presents less graininess in images.

According to the present invention, the display device includes a plurality of pixels aligned in a first direction and a second direction perpendicular to the first direction and arranged as a whole in a matrix form in a plan view, the plurality of pixels each including first to third subpixels arranged in the form of a delta in the plan view.

In the display device, expressions: pv

1

=pv

2

=pv/2; pv

3

=0; and ph

1

=ph

2

<ph/3 hold where: components of an arrangement interval between the plurality of pixels in the first and second directions are indicated by pv and ph, respectively; with respect to each of the plurality of pixels, components of the arrangement interval between the first and second subpixels in the first and second directions are indicated by pv

1

and ph

1

, respectively; components of the arrangement interval between the second and third subpixels in the first and second directions are indicated by pv

2

and ph

2

, respectively; and a component of the arrangement interval between the first and third subpixels in the first direction is indicated by pv

3

.

Further, expressions: pv

4

=pv/2; pv

5

=0; and ph

4

>ph/3 hold where: with respect to first and second subpixels among the plurality of pixels adjacent to each other in the second direction, components of the arrangement interval between the third subpixel of the first pixel and the first subpixel of the second pixel in the first and second directions are indicated by pv

4

and ph

4

, respectively; and a component of the arrangement interval between the second subpixel of the first pixel and the first subpixel of the second pixel in the first direction is indicated by pv

5

.

Further, adjacent ones of the plurality of pixels in the first direction have the same arrangement of the first to third subpixels.

In the display device, the minimum value of the arrangement interval between the first to third subpixels is smaller than that of the arrangement interval between three subpixels in conventional delta-arrangement pixels. Thus, color split is difficult to occur where the first to third subpixels display, for example, red, green and blue, respectively. Further, since the component of the arrangement interval between the second subpixel and the first and third subpixels in the first direction is equal to that in the conventional delta-arrangement pixels, the display device according to the present invention achieves high resolution for the number of pixels.

These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1

is a schematic plan view showing a display device according to a first preferred embodiment of the present invention;

FIG. 2

is a table showing evaluation results of color split in the display device according to the first preferred embodiment;

FIG. 3

is a table showing evaluation results of graininess in the display device according to the first preferred embodiment;

FIG. 4

is a schematic plan view showing a PDP according to the first preferred embodiment;

FIG. 5

show a schematic plan view and sectional views of the PDP according to the first preferred embodiment;

FIGS. 6 and 7

are schematic plan views showing the PDP according to the first preferred embodiment;

FIGS. 8

to

10

are schematic plan views showing first electrodes of a PDP according to a second preferred embodiment of the invention;

FIG. 11

is a schematic plan view showing a PDP according to a third preferred embodiment of the invention;

FIG. 12

is a schematic plan view showing a PDP according to a fourth preferred embodiment of the invention;

FIG. 13

is a schematic plan view showing a PDP according to a fifth preferred embodiment of the invention;

FIG. 14

is a schematic plan view showing a PDP according to a sixth preferred embodiment of the invention;

FIG. 15

is a schematic plan view showing a PDP according to a seventh preferred embodiment of the invention;

FIG. 16

is a schematic plan view showing a PDP according to an eighth preferred embodiment of the invention;

FIGS. 17 and 18

are schematic plan views showing a PDP according to a ninth preferred embodiment of the invention;

FIG. 19

is a schematic plan view showing a conventional trio-arrangement pixel; and

FIG. 20

is a schematic plan view showing a conventional delta-arrangement pixel.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

<First Preferred Embodiment>

FIG. 1

is a schematic plan view showing a display device

100

according to a first preferred embodiment. A display of the display device

100

includes a plurality of pixels PX aligned in a first (here, vertical) direction v and a second (here, horizontal) direction h perpendicular to the first direction v and arranged as a whole in a matrix form in the plan view of the display.

FIG. 1

shows four pixels PX arranged in a matrix of 2×2 as an example. An arrangement interval (hereinafter also briefly referred to as “interval”) between adjacent pixels PX in the first direction v is set in pv, and an interval between adjacent pixels PX in the second direction h is set in ph.

The arrangement interval between adjacent pixels PX is given as an interval (distance) between pixel centers of the adjacent pixels PX. The center of a pixel PX is given as an intersection of lines passing through midpoints of respective dimensions in the first and second directions v and h. Conversely, the center of a subpixel C can be decomposed into components in the first and second directions v and h (i.e., the center in the first and second directions v and h). The same explanation applies to the center of a subpixel C which will be described later. In this case, the center of a pixel PX is also given as, for example, the center of a triangle formed by connecting the centers of the three subpixels C forming a pixel PX arranged in the form of a delta.

Although it is possible to set pv and ph as pv≠ph, the following equation:

pv=ph=p (1)

shall hold in this case for ease of explanation and comparison with the conventional pixels PT and PD.

Each pixel PX is constituted by the three subpixels C arranged in the form of a delta in the plan view of the display. Hereinafter, the three subpixels C arranged in the form of a delta are distinguishably called “first to third subpixels C

1

, C

2

and C

3

” as necessary. The second subpixel C

2

corresponds to the single subpixel C present singly in the second direction h, and the first and third subpixels C

1

and C

3

correspond to the paired subpixels C aligned in the second direction h.

In the display device

100

, the first to third subpixels C

1

to C

3

are formed in the same shape and area, which shall be equal to those of the subpixels C in the conventional pixels PT and PD for ease of explanation. In short, the subpixels C

1

to C

3

are set in the form of rectangular with dimensions of (p/2) and (p/3) in the first and second directions v and h, respectively.

The subpixels C

1

to C

3

are unit regions whose display/non-display of predetermined luminous colors can be controlled in the plan view of the display (or, in a PDP which will be described later, unit regions whose emission/non-emission can be controlled). In contrast, regions whose display/non-display cannot be controlled (or, in the PDP which will be described later, regions that do not emit) are called “non-display (or non-luminous) areas NC”. In the display device

100

, the first to third subpixels C

1

to C

3

are capable of displaying red (R), green (G) and blue (B), respectively, as an example.

In the display device

100

, pixels PX adjacent in the first direction v have the same arrangement of the first to third subpixels C

1

to C

3

, while those adjacent in the second direction h have the single subpixel C

2

and the paired subpixels C

1

and C

3

arranged in reversed positions to each other in the first direction v (in other words, two pixels PX adjacent to each other in the second direction h are rotationally symmetrical about the center between the two pixels PX).

Particularly, in the display device

100

, each of the plurality of pixels PX is set to satisfy the following expressions:

pv

1

=

pv

2

=pv

/2 (2)

pv

3

=0 (3)

ph

1

=ph

2

<ph

/3 (4)

where:

components of the arrangement interval between the first and second subpixels C

1

and C

2

in the first and second directions v and h are indicated by pv

1

and ph

1

, respectively;

components of the arrangement interval between the second and third subpixels C

2

and C

3

in the first and second directions v and h are indicated by pv

2

and ph

2

, respectively; and

a component of the arrangement interval between the third and first subpixels C

3

and C

1

in the first direction v is indicated by pv

3

.

Further, two arbitrary pixels PX adjacent to each other in the second direction h (hereinafter distinguishably called “first and second pixels” ) are set to satisfy the following expressions:

pv

4

=pv

/2(

=p

/2) (5)

pv

5

=

0 (6)

ph

4

>ph

/3 (7)

where:

components of the arrangement interval between the third subpixel C

3

of the first pixel PX and the first subpixel C

1

of the second pixel PX in the first and second directions v and h are indicated by pv

4

and ph

4

, respectively; and

a component of the arrangement interval between the second subpixel C

2

of the first pixel PX and the first subpixel C

1

of the second pixel PX in the first direction v is indicated by pv

5

.

More specifically, in relation to the expressions (4) and (7), the display device

100

is set to satisfy the following expressions:

ph

1

=ph

2

=ph

/6(

<ph

/3) (8)

ph

4

=ph×

⅔(

>ph

/3 ) (9)

As described above, in the display device

100

D having the conventional delta-arrangement pixels PD (FIG.

20

), the subpixels C are arranged in the whole display at an equal interval of (p/3) with respect to the component of the arrangement interval in the second direction h. In contrast, the subpixels C

1

to C

3

in the display device

100

are arranged at unequal intervals with respect to the component of the arrangement interval in the second direction h. Specifically, as is apparent from the expressions (1), (4) and (7), with respect to the component in the second direction h in an arbitrary pixel PX, the interval between the first and second subpixels C

1

and C

2

is equal to that between the second and third subpixels C

2

and C

3

, whereas being smaller than that between the third subpixel C

3

of the arbitrary pixel PX and the first subpixel C

1

of a pixel PX adjacent to the arbitrary pixel PX in the second direction h.

According to the definition in the expressions (1), (8) and (9), the arrangement interval between the first and third subpixels C

1

and C

3

becomes the minimum. At this time, the following are true:

the minimum value of the arrangement interval between the first and third subpixels C

1

and C

3

is 0.33 p;

the minimum value of the arrangement interval between the first and second subpixels C

1

and C

2

is 0.53 p; and

the minimum value of the arrangement interval between the second and third subpixels C

2

and C

3

is 0.53 p.

Since the minimum value of the arrangement interval between the subpixels C is 0.6 p in each conventional pixel PD as described above, the minimum value in the display device

100

is smaller. Therefore, color split is difficult to occur according to the pixels PX.

On the other hand, the component of the arrangement interval between the single subpixel C

2

and the paired subpixels C

1

and C

3

in the first direction v is (p/2), which is equal to that in the conventional delta-arrangement pixels PD. This allows the display device

100

to achieve high resolution for the number of pixels.

According to the expression (4), the component of the arrangement interval between the first and third subpixels C

1

and C

3

in the second direction h in each pixel PX is smaller than that of the arrangement interval between the paired subpixels C in each conventional pixel PD. Therefore, even if a non-display area NC is provided between the first and third subpixels C

1

and C

3

in each pixel PX of the display device

100

, such non-display area NC is smaller than that present in the corresponding position in each pixel PD (FIG.

20

). According to the aforementioned definition of the shape, area and arrangement of the subpixels, it is possible to prevent such non-display area NC from being formed between the first and third subpixels C

1

and C

3

in each pixel PX as shown in FIG.

1

.

Therefore, when black layers are formed in the non-display areas NC of the display device

100

, part of the black layers present between the first and third subpixels C

1

and C

3

in each pixel PX is smaller than that in the conventional display device

100

D.

Further, according to the expression (7), it is possible to prevent the subpixels C

1

to C

3

of a pixel PX from being in contact with those of an adjacent pixel PX in the second direction h. This allows each non-display area NC to be formed with a pattern extending in the first direction v in the plan view.

Therefore, when the black layers are provided in the non-display areas NC of the display device

100

, the black layers are in the form of belts or stripes (black stripes) extending in the first direction v in the plan view.

Since the non-display areas NC lie scattered in the form of dots due to the arrangement position of the subpixels C and the like in the conventional display device

100

D, the black layers in the non-display areas NC are also provided in the form of dots (which are also called “black dots”). Each black dot is provided between the three subpixels C constituting one pixel PD, which is thus present singly. This appears to cause “graininess” to be readily seen.

On the other hand, since the black layers are formed in stripes in the display device

100

, the display device

100

presents less graininess than the conventional display device

100

D. This may be attributed to the same reason that the conventional display device

100

T having the trio-arrangement pixels PT presents less graininess. In other words, the black layers are formed in stripes (which are also called “black stripes) between pixels PT aligned in the first direction v (i.e., between subpixels C) in accordance with the shape of the non-display areas NC.

Even when a non-display area NC is present between the first and third subpixels C

1

and C

3

in each pixel PX of the display device

100

, a black layer to be provided in such non-display area NC is a dot smaller than that in the conventional display device

100

D. Therefore, even in this case, it is possible to suppress graininess in the display device

100

as compared to the display device

100

D.

FIG. 2

is a table showing subjective evaluation results of color split performed for the display device

100

(specifically, a PDP

101

which will be described later) together with evaluation results performed for the display device

100

D having the conventional delta-arrangement pixels PD and the display device

100

T having the conventional trio-arrangement pixels PT. The evaluations were conducted using the rating scale method, in which the display devices were each given any of marks of

2

,

1

and

0

for three categories, “no color-split”, “normal” and “color-split appears”, respectively. Seven people skilled in images conducted the evaluations while moving in the distance range of 2H to 3H (H is the height of a display (i.e., the dimension in the vertical direction)) which is in the vicinity of one minute angle.

FIG. 2

shows a dramatic improvement in suppressing color split in the pixels PX of the present embodiment as compared to the conventional pixels PD.

FIG. 3

is a table showing subjective evaluation results of graininess performed for the display device

100

(specifically, the PDP

101

which will be described later) together with evaluation results performed for the conventional display devices

100

D and

100

T. Such evaluations were conducted using the rating scale method, in which the display devices were each given any of marks of

2

,

1

and

0

for three categories, “no graininess”, “normal” and “graininess appears”, respectively. Seven people skilled in images conducted the evaluations while moving in the distance range of 2H to 3H (H is the height of the display (i.e., the dimension in the vertical direction)) which is in the vicinity of one minute angle.

FIG. 3

shows a dramatic improvement in suppressing graininess in the pixels PX of the present embodiment as compared to the conventional pixels PD.

Although a display device in which the single subpixel is a green subpixel and the paired subpixels are red and blue subpixels is employed as the display devices

100

and

100

D in the above evaluations, the delta-arrangement pixels PX of the present embodiment achieve improvement in suppressing color split and graininess with the red, green and blue subpixels arranged in any way.

Next, a specific example in the case that the above-described display device

100

is a plasma display panel (PDP) will be described.

FIG. 4

is a schematic plan (or layout) view showing the PDP

101

according to the present embodiment.

FIG. 5

is a schematic plan view showing part of

FIG. 4

enclosed by broken lines in rectangular (specifically, the part including the first subpixel C

1

) together with schematic sectional views taken along the lines I—I and II—II of the plan view. Further, for explanation,

FIGS. 6 and 7

are schematic plan views showing part of components extracted from FIG.

4

. Illustration of phosphor layers

2

and the like is omitted in

FIG. 4

, for example, for preventing complexity of illustration. Such omission will also be made in

FIGS. 6 and 7

which will be described later.

The PDP (or display device)

101

is generally called “three-electrode surface discharge type AC-PDP”, including first and second substrates

11

and

21

, a plurality of first electrodes

12

, a plurality of second electrodes

22

, a dielectric layer

23

, a rib (or barrier rib)

1

, the phosphor layers

2

and a plurality of black layers

24

.

FIG. 6

is a cutaway view of part of the rib

1

.

Specifically, the first and second substrates

11

and

21

are opposed to each other at a predetermined spacing, each being made of a glass substrate, for example. The plurality of first electrodes

12

are formed on a main surface of the first substrate

11

(on the side of the second substrate

21

) and aligned in the second direction h. Particularly, the plurality of first electrodes

12

include a plurality of (stripe or belt) electrodes

120

extending in the first direction v, a plurality of branch electrodes

122

(to be described later) scattered around on the PDP

101

and a plurality of trunk electrodes

121

connecting adjacent ones of the branch electrodes

122

in the first direction v. The branch electrodes

122

are (solid) rectangular, for example, arranged on both sides of the stripe electrodes

120

. The trunk electrodes

121

connect the branch electrodes

122

to one another on the far side of the stripe electrodes

120

. Further description of the three types of electrodes

120

,

121

and

122

will be made later.

On the other hand, the plurality of second electrodes

22

are formed on a main surface of the second substrate

21

(on the side of the first substrate

11

) and aligned in the first direction v. The second electrodes

22

each include a metal auxiliary electrode (also referred to as “bus electrode”)

221

and a plurality of transparent electrodes

222

connected to the metal auxiliary electrode

221

, projecting in the first direction v.

The plurality of transparent electrodes

222

alternately project in different directions (e.g., up and down directions in

FIG. 7

) with respect to the metal auxiliary electrode

221

. The transparent electrodes

222

of adjacent ones of the second electrodes

22

are opposed so as to form a discharge gap DG therebetween. Although

FIG. 5

illustrates the case that the transparent electrodes

222

and the metal auxiliary electrode

221

are provided in this order on the second substrate

21

, the electrodes

221

and

222

may be arranged in the reversed order or may be connected by their edges. The second and first electrodes

22

and

12

intersect grade-separately.

In the PDP

101

, where the second substrate

21

serves as a display surface or screen, the second electrodes

22

include the transparent electrodes

222

in order to lead out visible light effectively. The second electrodes

22

further include the metal auxiliary electrodes

221

of low impedance in order to supply the transparent electrodes

222

with current from a circuit part. Further description of the transparent electrodes

222

will be made later.

The dielectric layer

23

is formed on the second substrate

21

to cover the second electrodes

22

. Although detailed illustration is omitted, the dielectric layer

23

may include a cathode film made of MgO, for example, as a surface layer on the side of the first substrate

11

, i.e., as a portion exposed to discharge spaces DS which will be described later.

Provided in a space between the first and second substrates

11

and

21

is the (single) rib

1

in contact with the first electrodes

12

and the dielectric layer

23

. The rib

1

(

FIG. 6

) includes a plurality of portions formed on the metal auxiliary electrodes

221

extending in the second direction h in the plan view and a plurality of portions extending in the first direction v for connecting the plurality of portions extending in the second direction h to one another. The rib

1

is formed in meshes, each of which is rectangular in the plan view, for dividing the space between the first and second substrates

11

and

21

into a plurality of discharge spaces DS (in the form of rectangular in the plan view in this case). Each of the discharge spaces DS forms a discharge cell (i.e., the rib

1

surrounds the plurality of discharge spaces DS). Particularly, the plurality of discharge spaces DS each correspond to a subpixel C in the aforementioned display device

100

(

FIG. 1

) in the plan view. Discharge spaces DS corresponding to the first to third subpixels C

1

to C

3

are hereinafter referred to as “first to third discharge spaces DS

1

, DS

2

and DS

3

”.

The space between the first and second substrates

11

and

21

contains a plurality of spaces corresponding to the non-display areas (or non-luminous areas) NC (

FIG. 1

) other than the first to third discharge spaces DS

1

to DS

3

. These spaces corresponding to the non-display areas NC correspond to spaces between adjacent pixels PX in the second direction h and extend in the first direction v. Particularly, the first to third discharge spaces DS

1

to DS

3

are adjacent to one another with the rib

1

interposed therebetween without (spaces corresponding to) non-display areas NC interposed between the first to third discharge spaces DS

1

to DS

3

, i.e., between the first to third subpixels C

1

to C

3

. In the PDP

101

, the spaces corresponding to the non-display areas NC extending in the first direction v are divided into a plurality of spaces by the aforementioned plurality of portions of the rib

1

extending in the second direction h. The rib

1

serves to divide the discharge spaces DS

1

to DS

3

as well as to serve as a support for supporting the PDP

101

so as not to be broken by the atmospheric pressure.

The aforementioned plurality of branch electrodes

122

are opposed to the first and third discharge spaces DS

1

and DS

3

. The stripe electrodes

120

are each provided to be opposed to (i.e., in the plan view, to be hidden by) the portions of the rib

1

extending in the first direction v for dividing the first and third discharge spaces DS

1

and DS

3

. Accordingly, the first electrodes

12

are each opposed to any one of the first to third discharge spaces DS

1

to DS

3

.

Further, the aforementioned transparent electrodes

222

(therefore, the second electrodes

22

) are provided in such a manner that the discharge gaps DG are opposed to the first to third discharge spaces DS

1

to DS

3

, respectively. The discharge gaps DG opposed to the first to third discharge spaces DS

1

to DS

3

are hereinafter referred to as “first to third discharge gaps DG

1

, DG

2

and DG

3

”, respectively. The second discharge gap DG

2

is opposed to the stripe electrodes

120

of the first electrodes

12

with the second discharge space DS

2

interposed therebetween, while the discharge gaps DG

1

and DG

3

are opposed to the branch electrodes

122

of the first electrodes

12

with the first and third discharge spaces DS

1

and DS

3

interposed therebetween.

Further, the phosphor layers

2

are provided in the discharge spaces DS. Specifically, the phosphor layers

2

are each formed on the first substrate

11

and on side faces of the rib

1

to cover the first electrodes

12

in discharge spaces DS. In the PDP

101

, the phosphor layers

2

for emitting red (R), green (G) and blue (B) are provided in the first to third discharge spaces DS

1

to DS

3

, respectively.

Provided on the main surface of the second substrate

21

are the black layers

24

formed in the non-display areas NC in the plan view. Although

FIG. 4

shows the case that the black layers

24

are provided at a slight spacing from portions of the rib

1

forming the border between the non-display areas NC and the subpixels C

1

to C

3

, the black layers

24

may be provided to be in contact with or to overlap the portions of the rib

1

forming the above-described border.

The space between the first and second substrates

11

and

21

, more specifically, the discharge spaces DS and the space corresponding to the non-display areas NC, are filled with a discharge gas such as a gas mixture of Ne+Xe or that of He+Xe under a pressure not higher than the atmospheric pressure. The discharge gas is filled after air is exhausted from the space between the first and second substrates

11

and

21

.

Next, a method of driving the PDP

101

will be described. The PDP

101

is operable similarly to a PDP corresponding to the display device

100

D having the conventional pixels PD.

Specifically, emission/non-emission of discharge cells or subpixels C in the PDP

101

is controlled in a minimum time unit called “sub-field”. The sub-field is further divided into three periods, i.e., “reset period”, “writing period” and “sustain discharge period”.

In the reset period, a discharge history in a previous sub-field is reset. Specifically, wall charges stored on the dielectric layer

23

opposite to the second electrodes

22

in the previous sub-field are reset.

In the writing period, wall charges are provided only for the discharge cell(s) in which sustain discharge needs to be created in a subsequent sustain discharge period. Specifically, the plurality of second electrodes

22

are alternately selected in sequence. This selection is performed by applying a negative pulse voltage to a target one of the plurality of second electrodes

22

to be selected. With the timing of applying the pulse voltage to the target of the second electrodes

22

, a positive pulse voltage based on image data is applied to each of the first electrodes

12

, thereby causing “writing discharge” between the first and second electrodes in the desired discharge cell(s). With this writing discharge, positive wall charges are stored on the dielectric layer

23

opposite to the second electrodes

22

.

In the sustain discharge period, even numbered ones and odd numbered ones of the plurality of second electrodes

22

are alternately applied with a pulse-like voltage from outside. When a composite voltage of the voltage applied from outside and the voltage resulting from the wall charges stored in the previous writing period exceeds a firing voltage, discharge (sustain discharge) is caused. The phosphor layer

2

converts ultraviolet rays generated by the discharge into visible light, so that the discharge cell or subpixel C emits in a luminous color corresponding to the phosphor layer

2

.

As described above, the stripe electrodes

120

of the first electrodes

12

are opposed to the second discharge spaces DS

2

while being opposed to (i.e., hidden by) the portions of the rib

1

dividing the first and third discharge spaces DS

1

and DS

3

. This allows an electric field of a sufficient intensity for causing discharge to be applied to the second discharge spaces DS

2

while preventing such electric field from being applied to the first and third discharge spaces DS

1

and DS

3

(i.e., false discharge is suppressed). On the other hand, the branch electrodes

122

can be supplied with voltage through the trunk electrodes

121

, and an electric field of a sufficient intensity for causing discharge can be applied to the first and third discharge spaces DS

1

and DS

3

through the branch electrodes

122

.

As has been described, various driving methods applicable to the PDP having the conventional delta-arrangement pixels PD can be applied to the PDP

101

without modification. Therefore, the PDP

101

also enjoys the advantages that are obtainable by the aforementioned W electrode common address driving method, the current distributing method and the like.

Particularly, since the arrangement of the subpixels C in the above display device

100

is embodied in the PDP

101

, color split is difficult to occur in the PDP

101

, as a matter of course. Further, the PDP

101

presents less graininess because of the black layers

24

provided in the non-display areas NC.

Further, the black layers

24

can suppress reflection of outer light to improve the contrast ratio in a bright room. In the PDP

101

, light emitted from the discharge cells are not shielded as the black layers

24

are provided in the non-display areas NC. In short, the contrast ratio can be improved without degrading the luminous efficiency.

<Second Preferred Embodiment>

In place of the aforementioned first electrodes

12

, first electrodes

12

B

1

,

12

B

2

and

12

B

3

shown in schematic plan views of

FIGS. 8

to

10

may be employed in the PDP

101

. These first electrodes

12

B

1

,

12

B

2

and

12

B

3

each have a structure in which the branch electrodes

122

are replaced by branch electrodes

1221

,

1222

and

1223

, respectively, in the first electrodes

12

.

Specifically, the branch electrodes

1221

each have a hollow or O-shaped plane pattern formed by hollowing out the branch electrodes

122

. The branch electrodes

1222

each have a T-shaped plane pattern with the head of T placed toward a corresponding one of the stripe electrodes

120

and an end of the leg of T connected to a corresponding one of the trunk electrodes

121

. The branch electrode

1223

each have a U-shaped plane pattern with the bottom of U placed toward a corresponding one of the stripe electrodes

120

and an opening end of U connected to a corresponding one of the trunk electrodes

121

.

The branch electrodes

1221

,

1222

and

1223

are reduced in size as compared to the aforementioned (solid) rectangular branch electrodes

122

, which allows the electrostatic capacity between the first electrodes to be reduced. This achieves reduced reactive power in the writing period.

At least two types of electrodes among the branch electrodes

122

,

1221

,

1222

and

1223

may be used in combination.

<Third Preferred Embodiment>

FIG. 11

is a schematic plan view showing part of components of a PDP (or display device)

101

C according to a third preferred embodiment.

The PDP

101

C includes first electrodes (or first and second stripe (or belt) electrodes)

12

C in place of the first electrodes

12

in the aforementioned PDP

101

(FIG.

4

), while other components are basically similar to those of the PDP

101

.

The first electrodes

12

C of the PDP

101

C are each in the form of stripe or belt extending in the first direction v and opposed to any one of the discharge spaces DS

1

to DS

3

(

FIG. 6

) aligned in the first direction v. In this case, the first electrodes (or first stripe electrodes)

12

C opposed to second discharge spaces DS

2

aligned in the first direction v are opposed to (i.e., in the plan view, are hidden by) portions of the rib

1

dividing the first and third discharge spaces DS

1

and DS

3

similarly to the aforementioned stripe electrodes

120

. Further, the first electrodes (or second stripe electrodes)

12

C opposed to first discharge spaces DS

1

aligned in the first direction v are opposed to (i.e., are hidden by) portions of the rib

1

defining the second discharge spaces DS

2

. Similarly, the first electrodes (or second stripe electrodes)

12

C opposed to third discharge spaces DS

3

aligned in the first direction v are opposed to (i.e., are hidden by) the portions of the rib

1

defining the second discharge spaces DS

2

. At this time, the first electrodes

12

C are aligned in the second direction h with the same component of the arrangement interval between subpixels C in the second direction h.

Such shape and arrangement of the first electrodes

12

C allow an electric field. of a sufficient intensity for causing discharge to be applied to discharge spaces DS to which the first electrodes

12

C are opposed while preventing such electric field from being applied to discharge spaces DS to which the first electrodes

12

C are not opposed (i.e., false discharge is suppressed).

In the aforementioned PDP

101

, the branch electrode

122

each need to be aligned accurately with each discharge space DS. In contrast, the first electrodes

12

C are opposed to the first to third discharge spaces DS

1

to DS

3

, which eliminates the need of separately using the branch electrodes

122

and the like. Thus, there is no need to align branch electrodes in the first direction v, which enables simplification of manufacturing processes.

<Fourth Preferred Embodiment>

FIG. 12

is a schematic plan view showing part of components of a PDP (or display device)

101

D according to a fourth preferred embodiment.

The PDP

101

D includes a plurality of ribs

1

D in place of the rib

1

in the aforementioned PDP

101

(FIG.

4

), while other components are basically similar to those of the PDP

101

. Although the ribs

1

D appear to be present above the second electrodes

22

(on this side of the sheet of drawing) in

FIG. 12

for ease of explanation, components of the PDP

101

D are similar to those of the PDP

101

(

FIG. 5

) in arrangement position (arrangement order). Such illustration will also be made in

FIGS. 13

to

18

which will be described later.

The plurality of ribs

1

D of the PDP

101

D each have a structure in which the portions of the rib

1

dividing the non-display areas NC extending in the second direction h are removed from the rib

1

. In other words, the plurality of ribs

1

D divide the plurality of first to third discharge spaces DS

1

to DS

3

similarly to the rib

1

, whereas not being connected to one another in the second direction h.

Accordingly, the spaces corresponding to the non-display areas NC extend entirely in the first direction v. Therefore, the plurality of ribs

1

D achieves higher exhaust conductance in the exhausting step to be performed before filling the discharge gas than the mesh-like rib

1

spread around entirely. Since the plurality of first to third discharge spaces DS

1

to DS

3

are also divided by the plurality of ribs

1

D, creation of discharge in the first to third discharge spaces DS

1

to DS

3

is not affected even when the plurality of ribs

1

D are not connected to one another.

The plurality of ribs

1

D may be applied to the aforementioned PDP

101

C or may be changed in shape in the plan view like a plurality of ribs

1

E which will be described later.

<Fifth Preferred Embodiment>

In the above-described PDP

101

and the like, the first electrodes

12

are opposed to the rib

1

so as to suppress false discharge in subpixels C other than desired ones. However, when the rib

1

overlaps the first electrodes

12

to a great extent, capacitive coupling may increase, causing reactive power to be increased. Thus, a PDP capable of reducing such reactive power will be described in this fifth preferred embodiment.

FIG. 13

is a schematic plan view showing part of components of a PDP (or display device)

101

E according to the fifth preferred embodiment.

The PDP

101

E includes the plurality of ribs

1

E in place of the plurality of ribs

1

D in the aforementioned PDP

101

D (FIG.

12

), while other components are basically similar to those of the PDPs

101

and

101

D.

The ribs

1

E each have a diamond-like mesh structure in the plan view, for dividing the plurality of first to third discharge spaces DS

1

to DS

3

. The ribs

1

E are each formed in such a manner that the discharge spaces DS, i.e., subpixels C have the same size in the plan view with a diamond shape longer in the first direction v. The first to third discharge spaces DS

1

to DS

3

are adjacent to one another with the ribs

1

E interposed therebetween in each pixel PX without (the spaces corresponding to) non-display areas NC interposed between the first to third discharge spaces DS

1

to DS

3

, i.e., the first to third subpixels C

1

to C

3

.

Further, the ribs

1

E are provided such that portions corresponding to tops

1

Et of the diamond shape are opposed to the plurality of first electrodes

12

in the plan view. More specifically, the ribs

1

E are each provided such that three tops

1

Et of two diamond-like meshes dividing the first and third discharge spaces DS

1

and DS

3

aligned in the second direction h are opposed to the first electrodes

12

, respectively.

In this case, two of the three tops

1

Et on the both sides aligned in the second direction h form corner portions (projecting corner portions in the plan view)

1

Ec of the peripheries of the ribs

1

E. The corner portions

1

Ec of the ribs

1

E are each set to form an angle greater than 90° in the plan view.

As described above, the plurality of ribs

1

E are opposed to the first electrodes

12

at the corner portions

1

Et of the diamond-like meshes. This allows capacitive coupling to be reduced as compared to the aforementioned ribs

1

D, resulting in a reduction in reactive power.

Further, with the ribs

1

E, it is possible to increase an alignment margin in the second direction h. For instance, when an alignment displacement occurs in the second direction h between the rib

1

and the first electrodes

12

in the PDP

101

(FIG.

6

), the first electrodes

12

are exposed in the plan view into the first or third discharge space DS

1

or DS

3

with a large exposed area although the alignment displacement is small. In contrast, if such alignment displacement occurs in the PDP

101

E, the first electrodes

12

are similarly exposed into the first or third discharge space DS

1

or DS

3

. However, the exposed area is small. In short, the PDP

101

E is less likely to cause false writing than the PDP

101

when the same displacement occurs, allowing the alignment margin in the second direction h to be increased.

Ribs are generally formed by firing (or burning) a paste material. Thus, tensile forces resulting from thermal contraction may be generated in a firing process, which may cause the ribs to be deformed at the firing. For instance, in the above-described rib

1

(FIG.

6

), resultant vectors of tensile forces exerted on connected portions (or intersecting portions) of parts extending in the first and second directions v and h are directed to one direction. The rib

1

is pulled in the direction, and consequently, may be cracked. Further, the above-described ribs

1

D (

FIG. 12

) have corner portions on their peripheries. The corner portions each form an angle of 90°, so that resultant vectors of tensile forces exerted on the corner portions are strongly directed to the inside of the corner portions (i.e., to the inside of the ribs

1

D). Therefore, the ribs

1

D may be greatly deformed at the firing.

In contrast, the ribs

1

E, being formed in diamond-like meshes, allows resultant vectors of tensile forces generated at intersecting portions

1

Ek at the firing to be reduced to zero. The ribs

1

E can thus be prevented from being cracked due to the above-described tensile forces. Further, the corner portions

1

Ec of the ribs

1

E each form an angle greater than 90°, so that the resultant vectors of tensile forces exerted on the corner portions

1

Ec are relaxed as compared to the ribs

1

D (having corner portions of 90°). The ribs

1

E can thus be prevented from being deformed due to firing.

<Sixth Preferred Embodiment>

As described above, the ribs

1

E of the PDP

101

E (FIG.

13

), being formed in diamond-like meshes, can be prevented from being cracked and deformed due to firing. However, the subpixels C are of diamond shape longer in the first direction v in accordance with the plane pattern of the ribs

1

E, so that resolution in the first direction v in the PDP

101

E is lower than that in the PDP

101

(

FIG. 4

) and the PDP

101

D (FIG.

12

). Therefore, description will be made in this preferred embodiment on a PDP capable of achieving resolution of the same level as that of the PDPs

101

and

101

D while preventing ribs from being cracked and deformed due to firing.

FIG. 14

is a schematic plan view showing part of components of a PDP (or display device)

101

F according to the sixth preferred embodiment.

The PDP

101

F includes a plurality of ribs

1

F in place of the plurality of ribs

1

D in the aforementioned PDP

101

D (FIG.

12

), while other components are basically similar to those of the PDPs

101

and

101

D.

The ribs IF each have a hexagonal mesh structure in the plan view, for dividing the plurality of first to third discharge spaces DS

1

to DS

3

. The ribs

1

F are each formed in such a manner that the discharge spaces DS, i.e., subpixels C are of hexagonal shape having the same size in the plan view. The first to third discharge spaces DS

1

to DS

3

are adjacent to one another with the ribs

1

F interposed therebetween in each pixel PX, without (the spaces corresponding to) non-display areas NC interposed between the first to third discharge spaces DS

1

to DS

3

, i.e., the first to third subpixels C

1

to C

3

.

Further, portions of each rib

1

F forming a pair of opposed sides of the hexagon extend in the first direction v. Such portions, of two hexagonal meshes, extending in the first direction v for dividing the first and third discharge spaces DS

1

and DS

3

are opposed to the first electrodes

12

similarly to the ribs

1

D. Particularly, the above-described portions of the ribs

1

F extending in the first direction v have substantially the same length as the corresponding portions of the ribs

1

D.

Those of corner portions

1

Fc of hexagonal meshes which are opposed to the first electrodes

12

are corner portions

1

Fc of the peripheries of the ribs

1

F (i.e., projecting corner portions in the plan view in this case). The corner portions

1

Fc of the ribs

1

F are each set to form an angle greater than 90° in the plan view.

The ribs

1

F, being formed in hexagonal meshes, achieve higher resolution in the first direction v than the ribs

1

E formed in diamond-like meshes. Further, the above-described portions of the ribs

1

F extending in the first direction v are set to have substantially the same length as the corresponding portions of the ribs

1

D, so that the PDP

101

F achieves resolution in the first direction v of substantially the same level as that of the PDPs

101

and

101

D.

Further, the ribs

1

F formed in hexagonal meshes allows resultant vectors of tensile forces generated at intersecting portions

1

Fk of the ribs

1

F when firing (a paste material for) the ribs to be reduced as compared to that exerted on the intersecting portions or connected portions of the ribs

1

D (in the form of T). In other words, although strong tensile forces are exerted in one direction at the intersecting portions of the ribs

1

D, such tensile forces can be suppressed by the ribs formed in hexagonal meshes. Therefore, it is possible to prevent the plurality of ribs

1

F from being cracked due to the above-described tensile forces.

Further, since the corner portions

1

Fc of the ribs

1

F each form an angle greater than 90°, so that the resultant vectors of tensile forces exerted on the corner portions

1

Fc are relaxed as compared to the ribs

1

D (having corner portions of 90°), for example. The ribs

1

F can thus be prevented from being deformed due to firing.

As has been described, the PDP

101

F is capable of achieving resolution of the same level as that of the PDPs

101

and

101

D while preventing ribs

1

F from being cracked and deformed due to firing.

<Seventh Preferred Embodiment>

FIG. 15

is a schematic view showing part of components of a PDP (or display device)

101

G according to a seventh preferred embodiment.

The PDP

101

G includes a plurality of ribs

1

G in place of the plurality of ribs

1

D in the aforementioned PDP

101

D (FIG.

12

), while other components are basically similar to those of the PDPs

101

and

101

D.

The plurality of ribs

1

G have a structure in which portions of the plurality of ribs

1

D defining the second discharge spaces DS

2

are extended in the second direction h. Specifically, each rib

1

G is formed in such a manner that the second discharge space DS

2

becomes larger, more particularly, larger in the second direction h, than the first and third discharge spaces DS

1

and DS

3

in the plan view. Therefore, the second subpixel C

2

is larger than the first and third subpixels C

1

and C

3

in the PDP

101

G.

In each pixel PX of the PDP

101

G, the second subpixel C

2

in the second direction h is set to have a dimension which is substantially the same as that from an end of the first subpixel C

1

in the second direction h (the end on the opposite side of the third subpixel C

3

) to an end of the third subpixel C

3

in the second direction h (the end on the opposite side of the first subpixel C

1

). Therefore, portions of the ribs

1

G extending in the first direction v for forming the second discharge space DS

2

and those of the ribs

1

G extending in the first direction v for forming the first discharge space DS

1

are substantially on a straight line. Similarly, the portions forming the second discharge space DS

2

and those of the ribs

1

G forming the third discharge space DS

3

are substantially on a straight line. Thus, a forming process of the ribs

1

G having such configuration is simplified as compared to the ribs

1

D (FIG.

12

), for example.

Further, in the PDP

101

G, the first to third subpixels C

1

to C

3

are set to emit in red (R), blue (B) and green (G), respectively.

According to the PDP

101

G, the phosphor layers

2

(

FIG. 5

) are provided in the second discharge spaces DS

2

by a larger area than in the first and third discharge spaces DS

1

and DS

3

resulting from a difference in area between the discharge spaces DS

1

, DS

2

and DS

3

. When the transparent electrodes

222

have the same size, (surface) discharge is caused to the same extent, so that the luminous efficiency is improved as the area to which the phosphor layers

2

are applied becomes larger. In other words, the luminous efficiency of the second subpixel C

2

can be improved as compared to that of the first and third subpixels C

1

and C

3

. Consequently, this allows the second subpixel C

2

to have higher luminance.

The effect of improvement in luminous efficiency is obtainable when the large second subpixel C

2

emits in either luminous color, and becomes remarkable when the second subpixel C

2

is set to be the blue subpixel as in the PDP

101

G. This is generally attributed to that a phosphor for emitting blue has lower luminance than those for emitting other luminous colors with the same power being applied. Such improvement in luminous efficiency of blue in the PDP

101

G allows a color temperature when displaying white to be improved as compared to the PDPs

101

and

101

D, for example.

The first to third subpixels C

1

to C

3

of the PDP

101

G, although not being of a uniform size, satisfy the above-described expressions (1) through (7), and further, (8) and (9), similarly to the display device

100

. Therefore, the PDP

101

G achieves the same effects as those in the display device

100

and the PDP

101

.

The form of the ribs

1

G may be applied to the aforementioned single rib

1

(FIG.

6

), which thereby brings about the same effects. According to the plurality of ribs

1

G, the effect of improving exhaust conductance is also obtainable at the same time,

<Eighth Preferred Embodiment>

FIG. 16

is a schematic view showing part of components of a PDP (or display device)

101

H according to an eighth preferred embodiment.

The PDP

101

H includes a plurality of first and second electrodes

12

H and

22

H in place of the plurality of first and second electrodes

12

and

22

in the aforementioned PDP

101

G (FIG.

15

), while other components are basically similar to those of the PDP

101

D.

The second electrodes

22

H of the PDP

101

H each have a structure in which the transparent electrodes

222

of the aforementioned second electrodes

22

opposed to the second discharge spaces DS

2

are made longer than the transparent electrodes

222

opposed to the first and third discharge spaces DS

1

and DS

3

. In other words, portions of each second electrode

22

H in the PDP

101

H forming the second discharge gap DG

2

are larger than those forming the first and third discharge gaps DG

1

and DG

3

.

Therefore, larger power can be applied to the second discharge space DS

2

than the first and third discharge spaces DS

1

and DS

3

with the same voltage being applied, so that luminance of the second subpixel C

2

can be improved as compared to, for example, the PDPs

101

and

101

D, and further, the PDP

101

G. Since the phosphor layers

2

for emitting blue are provided in the second discharge spaces DS

2

in the PDP

101

H similarly in the PDP

101

G, a color temperature when displaying white can be improved as compared to those in, for example, the PDPs

101

and

101

D, and further, the PDP

101

G.

Although the first electrodes

12

H of the PDP

101

H each include the stripe electrodes

120

, the trunk electrodes

121

and the branch electrodes

122

similarly to the aforementioned first electrodes

12

, the trunk electrodes

121

of the first electrodes

12

H are provided in the non-display areas NC in the plan view. With such change in arrangement position of the trunk electrodes

121

, the branch electrodes

122

of the first electrodes

12

H extend longer in the second direction h than those of the first electrodes

12

and are connected to the trunk electrodes

121

. The stripe electrodes

120

of the first electrodes

12

H are provided similarly to those of the first electrodes

12

.

Since the first electrodes

12

H are provided as described above, it is possible to locate the first electrodes

12

H (specifically, the trunk electrodes

121

) away from the large transparent electrodes

222

opposed to the second discharge spaces DS

2

as compared to the structure to which the first electrodes

12

are applied. It is therefore possible to reduce an electric field intensity between the large transparent electrodes

222

and the first electrodes

12

H, thereby suppressing false discharge.

Further, the branch electrodes

122

of the first electrodes

12

H are more difficult to be opposed to the second discharge spaces DS

2

as compared to the case of using the first electrodes

12

even if alignment displacement occurs to some extent between the first electrodes

12

H and the ribs

1

G in the second direction h. In short, the first electrodes

12

H achieve an increased alignment margin in the second direction h.

<Ninth Preferred Embodiment>

FIG. 17

is a schematic view showing a PDP (or display device)

101

I according to a ninth preferred embodiment, and

FIG. 18

is a schematic plan view showing part of the components extracted from FIG.

17

.

The PDP

101

I includes sa rib

1

I, a plurality of first electrodes

12

I and black layers

24

I in place of the rib

1

, the plurality of first electrodes

12

and the black layers

24

, respectively, in the aforementioned PDP

101

(FIG.

4

), while other components are basically similar to those of the PDP

101

.

Unlike the aforementioned PDP

101

or the like, the discharge spaces DS in the PDP

101

I do not correspond to subpixels C. The subpixels C in the PDP

101

I are formed by combination of the discharges spaces DS and the black layers

24

I.

Specifically, the rib

1

I of the PDP

101

I divides the space between the first and second substrates

11

and

21

into the plurality of the first to third discharge spaces DS

1

to DS

3

arranged in the form of a delta in the plan view.

In the PDP

101

I, the first to third discharge spaces DS

1

to DS

3

are hexagonal of the same size in the plan view. The first to third discharge spaces DS

1

to DS

3

are adjacent to one another with the rib

1

I interposed therebetween without (a space corresponding to) non-display areas NC interposed therebetween. In short, the rib

1

I divides the space between the first and second substrates

11

and

21

into hexagonal meshes. Further, one pair of opposed sides of each hexagon of the rib

1

I extends in the first direction v.

As shown in

FIG. 18

, the component of the arrangement interval between the first to third discharge spaces DS

1

, DS

2

and DS

3

in the second direction h is set in ph/

3

(=p/3), while components of the arrangement intervals between the second discharge space DS

2

and the first and third discharge spaces DS

1

and DS

3

in the first direction v are set in pv/2 (=p/2).

The plurality of first electrodes

12

I of the PDP

101

I are basically similar to the plurality of first electrodes

12

C (FIG.

11

). In other words, the first electrodes

12

I are each in the form of stripe extending in the first direction v opposed to any one of the discharge spaces DS

1

to DS

3

aligned in the first direction v. In this case, the first electrodes

12

I opposed to the second discharge spaces DS

2

aligned in the first direction v are opposed to (i.e., in the plan view, is hidden by) the portions of the rib

1

I dividing the first and third discharge spaces DS

1

and DS

3

. Similarly, the first electrodes

12

I opposed to the first discharge spaces DS

1

aligned in the first direction v are opposed to the portions of the rib

1

I dividing the second discharge spaces DS

2

and the third discharge spaces DS

3

adjacent in the second direction h, while the first electrodes

12

I opposed to the third discharge spaces DS

3

aligned in the first direction v are opposed to the portions of the rib

1

I dividing the second discharge spaces DS

2

and the first discharge spaces DS

1

adjacent in the second direction h. The first electrodes

12

I are aligned in the second direction h with the same component of the arrangement interval between the discharge spaces DS in the second direction h.

The transparent electrodes

222

of the second electrodes

22

of the PDP

101

I are provided in such a manner that the first to third discharge gaps DG

1

to DG

3

are opposed to the first to third discharge spaces DS

1

to DS

3

similarly to the PDP

101

, whereas a component of the arrangement interval of the transparent electrodes

222

in the second direction h is different from that in the PDP

101

due to the difference in arrangement of the first to third discharge spaces DS

1

to DS

3

.

The black layers

24

I of the PDP

101

I are provided on the second substrate

21

similarly to the black layers

24

. Particularly, as shown in

FIG. 17

, the black layers

24

I are so provided as to cover part of the first to third discharge spaces DS

1

to DS

3

in the plan view (i.e., so as to reduce the size of the discharge spaces DS

1

to DS

3

). That is, the black layers

24

I limit the position, shape and size of an opening through which visible light generated in the discharge spaces DS is led out. In other words, the black layers

24

I convert part of the plane pattern of the discharge spaces DS into non-display areas NC whose display/non-display cannot be controlled. Thereby formed are the subpixels C

1

to C

3

which are unit regions whose display/non-display of predetermined luminous colors can be controlled in the plan view of the display.

Specifically, the black layers

24

I are so provided as to cover both edge portions of the second discharge space DS

2

in the second direction h in each pixel PX in the plan view, thereby forming the second subpixel C

2

. Further, the black layers

24

I are so provided as to cover an edge portion of the first discharge space DS

1

far from the third discharge space DS

3

in the second direction h in each pixel PX in the plan view, thereby forming the first subpixel C

1

. Furthermore, the black layers

24

I are so provided as to cover an edge portion of the third discharge space DS

3

far from the first discharge space DS

1

in the second direction h in each pixel PX in the plan view, thereby forming the third subpixel C

3

.

The PDP

101

I, being provided with the black layers

24

I such that the subpixels C

1

to C

3

satisfy the expressions (1) to (7), and further, (8) and (9), achieves the same effects as those in the display device

100

and the PDP

101

. Conversely, when the PDP

101

I is not provided with the black layers

24

I (FIG.

18

), color split easily occurs similarly to the conventional delta-arrangement pixels PD (FIG.

20

). Further, the black layers

24

I achieve an improved contrast ratio in a bright room. It is possible to suppress graininess in the PDP

101

I as well by forming the black layers

24

I in stripes extending in the first direction v as a whole, as shown in FIG.

17

.

Further, according to the arrangement of the black layers

24

I, the first to third subpixels C

1

to C

3

can easily be formed from the first to third discharge spaces DS

1

to DS

3

.

The black layers

24

I may be provided in such a manner that the second subpixel C

2

becomes larger similarly to the PDP

101

G (FIG.

15

).

According to the configuration of the PDP

101

I from which the black layers

24

I are removed (FIG.

18

), the subpixels C

1

to C

3

are larger because of the absence of the non-display areas NC, so that a PDP of high luminance can be obtained. In such PDP, a side face of the rib

1

I is smaller than its bottom face in area, which allows visible light to be easily led out, resulting in high luminous efficiency.

In view of this point, visible light generated in the discharge spaces DS is shielded by the black layers

24

I, so that the PDP

101

I might have lower luminance and luminous efficiency than the PDP not provided with the black layers

24

I. However, the black layers

24

I, provided at edge portions of the discharge spaces DS emitting relatively feeble light, do not remarkably reduce luminance and luminous efficiency. Further, it is possible to suppress reduction in luminance and luminous efficiency by applying a material of high reflectance such as titanium oxide or aluminum oxide onto the black layers

24

I (on the first substrate

11

side) so as be opposed to the discharge spaces DS. In short, visible light generated in the discharge spaces DS, after being reflected by the material of high reflectance and further by the rib

1

I and the like, can be led out as display light.

<Variant>

The black layers

24

and

24

I may be of colors other than black and may include a layer of such dark colors that desired light shielding and low reflectivity are obtainable.

Although the PDPs have been described as specific examples of the display device

100

(

FIG. 1

) in the above description, the display device

100

may also be embodied by liquid crystal displays (LCDs), field emission displays (FEDs) and the like.

While the invention has been shown and described in detail, the foregoing description is in all aspects illustrative and not restrictive. It is therefore understood that numerous modifications and variations can be devised without departing from the scope of the invention.

Number	Name	Date	Kind
5801794	Lehureau et al.	Sep 1998	A
6064424	van Berkel et al.	May 2000	A
6072272	Rumbaugh	Jun 2000	A

Number	Date	Country
2000-298451	Oct 2000	JP
2000-357463	Dec 2000	JP
2001-135242	May 2001	JP

Display device

Information

Patent Number

Date Filed

Date Issued

Inventors

Original Assignees

Examiners

Agents

CPC

US Classifications

Field of Search

US

International Classifications

Abstract

Description

Claims

Priority Claims (1)

US Referenced Citations (3)

Foreign Referenced Citations (3)