JP3625620B2 - Plasma display panel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a surface-discharge type plasma display panel (PDP: Plasma Display Panel).
[0002]
The surface discharge type PDP is commercialized as a color display device for a television or a computer system. Although the screen size has reached 42 inches, a larger screen is desired in the market.
[0003]
[Prior art]
A PDP is a flat type display device comprising a pair of substrates provided with components such as electrodes, as is well known, and a surface discharge type PDP is a pair of main electrodes serving as an anode and a cathode in a discharge for ensuring luminance. Are PDPs arranged in parallel on the same substrate to generate a surface discharge along the substrate surface. A structure in which the main electrodes are shared by adjacent lines is also known, but basically, the main electrodes are arranged in pairs for each line, and the total number is 2n (n is the number of lines). In the surface discharge type PDP, the phosphor layer for color display is provided on the other substrate opposite to the substrate on which the main electrode is provided, thereby reducing deterioration of the phosphor layer due to ion bombardment during discharge. it can. Those in which the phosphor layer is disposed on the back side substrate are referred to as “reflection type”, and conversely, those in which the phosphor layer is disposed on the front side substrate are referred to as “transmission type”. A reflection type in which the front side surface of the phosphor layer is a light emitting surface is advantageous in increasing the brightness.
[0004]
In the reflective surface discharge PDP, the main electrode is disposed on the front substrate. In order to avoid shielding the display light, the main electrode needs to be a transparent electrode. However, the conductivity of transparent conductive materials such as ITO and Nesa is insufficient for practical use. Therefore, in the surface discharge type PDP, a laminated body of a transparent conductive film and a metal film supplementing conductivity is provided as a main electrode.
[0005]
FIG. 5 is a plan view showing the structure of the main electrode pair of the conventional surface discharge type PDP 90.
In the PDP 90, a pair of strip-like main electrodes Xj and Yj are arranged for each line of the matrix display. Each of these main electrodes Xj and Yj includes a transparent conductive film 410 and a metal film 420 having a smaller width. The transparent conductive film 410 and the metal film 420 are in the form of a straight strip inside the screen region E1 in which cells are arranged vertically and horizontally. In order to reduce the amount of light shielding as much as possible, the metal film 420 is overlapped on the transparent conductive film 410 so as to approach the edge opposite to the gap (surface discharge gap) g between the transparent conductive films 410. In addition, the metal film 420 of each main electrode Xj, Yj is distributed to the left and right to be connected to an external drive circuit and extends from the screen region E1 to the vicinity of the edge of the substrate, and is connected to the wiring outside the screen region E1. Patterned into a suitable shape (such as a folded band).
[0006]
Conventionally, the width w of the metal film 420 is constant within the range of the screen region E1. The distance d2 between the metal films 420 and the dimension d1 of the surface discharge gap g were also constant.
[0007]
[Problems to be solved by the invention]
By the way, in the PDP, as the screen becomes larger, the influence of the voltage drop due to the resistance of the electrode becomes serious. That is, a decrease in discharge intensity (luminance) due to a decrease in voltage applied to the cell (voltage drop) becomes significant.
[0008]
In order to reduce the voltage drop, the metal film 420 may be thickened to reduce the resistance. However, when the width of the metal film 420 is increased, the “aperture ratio” that is the ratio of the non-light-shielding portion of the cell is decreased and the light emission efficiency is lowered, so that the width cannot be extremely increased.
[0009]
An object of the present invention is to reduce voltage drop as much as possible while ensuring uniformity of the cell aperture ratio.
[0010]
[Means for Solving the Problems]
In the PDP according to the first aspect of the present invention, a pair of band-like electrodes are arranged for each matrix display line on the inner surface of the front side substrate in the pair of substrates sandwiching the discharge space. The width of the metal film of one electrode of each line gradually decreases from one end to the other end in the line direction in the screen region, and conversely the metal of the other electrode The width of the film is gradually increased, and the distance between the metal films of the pair of electrodes is constant regardless of the position in the line direction.
[0011]
3. The PDP according to claim 2, wherein edges of the transparent conductive film and the metal film constituting each main electrode on the side far from the surface discharge gap are substantially parallel, and the metal film is a surface discharge gap. The transparent conductive film is superimposed on the side far from the side.
[0012]
In the PDP according to the third aspect of the present invention, the interval between the transparent conductive films of the pair of electrodes is made non-uniform in the line direction by changing the width of at least one transparent conductive film in units of cells in each line. ing.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a block diagram of a plasma display device 100 according to the present invention.
The plasma display device 100 includes an AC drive type PDP 1 which is a matrix type color display device and a drive unit 80 for selectively lighting cells constituting a screen (screen), and is a wall-mounted television receiver. Used as a computer system monitor.
[0014]
The PDP 1 is a surface discharge type PDP in which a pair of sustain electrodes (main electrodes) X and Y are arranged in parallel, and each cell has a three-electrode structure electrode matrix corresponding to the sustain electrodes X and Y and the address electrodes A. Have. In the screen area E1, the sustain electrodes X and Y extend in the line direction (horizontal direction) of the screen, and the address electrode A is a data electrode for selecting cells in units of columns and extends in the column direction (vertical direction). . The sustain electrode X of each line is electrically shared and is connected to the drive unit 86 at one end (left end in the figure) in the line direction. On the other hand, the sustain electrode Y of each line is connected to the drive unit 86 independently from each other on the other end (right end in the figure) in the line direction, and is used as a scan electrode for selecting cells in line units. The address electrode A is a data electrode for selecting cells in units of columns and extends in the column direction (vertical direction).
[0015]
The drive unit 80 includes a controller 81, a frame memory 82, an X driver circuit 86, a Y driver circuit 87, an address driver circuit 88, and a power supply circuit (not shown). Multi-value video data DR, DG, DB indicating the RGB luminance level (gradation level) of each pixel is input to the drive unit 80 together with various synchronization signals. The video data DR, DG, and DB are temporarily stored in the frame memory 82, then converted into subframe data Dsf for each color by the controller 81, and stored in the frame memory 82 again. The subframe data Dsf is a set of binary data indicating whether or not the cells need to be lit in each subframe obtained by dividing one frame for gradation display. The X driver circuit 86 is responsible for voltage application to the sustain electrode X, and the Y driver circuit 87 is responsible for voltage application to the sustain electrode Y. The address driver circuit 88 selectively applies an address voltage to the address electrode A in accordance with the subframe data Dsf transferred from the frame memory 82.
[0016]
FIG. 2 is a perspective view showing the internal structure of the PDP 1 of the present invention.
In the PDP 1, a pair of sustain electrodes X and Y are arranged on the inner surface of the glass substrate 11 on the front side of the pair of substrates sandwiching the discharge space 30 for each line L that is a cell row in the horizontal direction of the screen. Each of the sustain electrodes X and Y includes a transparent conductive film 41 and a metal film 42 for reducing the resistance value, and is covered with a dielectric layer 17 for AC driving. An MgO film 18 is deposited on the surface of the dielectric layer 17. The dielectric layer 17 and the MgO film 18 have translucency. The substrate on which the laminate of the sustain electrodes X and Y, the dielectric layer 17 and the protective film is formed is called a substrate structure. On the inner surface of the glass substrate 21 on the back side, a base layer 22, an address electrode A, an insulating layer 24, a partition wall 29, and three color (R, G, B) phosphor layers 28R, 28G, 28B for color display. Is provided. Each partition wall 29 is linear in plan view. The partition walls 29 divide the discharge space 30 into sub-pixels (unit light emitting regions) in the line direction, and the gap size of the discharge space 30 is defined to a constant value (about 150 μm). The discharge space 30 is filled with a discharge gas in which a small amount of xenon is mixed with neon. The phosphor layers 28R, 28G, and 28B are locally excited by ultraviolet rays generated by discharge and emit visible light of a predetermined color.
[0017]
One pixel of display is composed of three sub-pixels arranged in the line direction. The structure within each subpixel is a cell. Since the arrangement pattern of the barrier ribs 29 is a stripe pattern, the portion corresponding to each column in the discharge space 30 is continuous in the column direction across all the lines. The emission colors of the subpixels in each column are the same.
[0018]
In the PDP 1 having the above structure, predetermined constituent elements are separately provided for the glass substrates 11 and 21 to produce the front and back substrate structures, and both substrate structures are overlapped to seal the periphery of the opposing gap. Manufactured by a series of steps for filling the interior exhaust and discharge gas. In the production of the substrate structure for the front surface, the sustain electrodes X and Y, which are the features of the present invention, form a transparent conductive film 41 by patterning an ITO thin film, and then, for example, have a three-layer structure of chromium-copper-chromium. It is formed by depositing a metal thin film on almost the entire surface of the glass substrate 11 and patterning it by photolithography.
[0019]
FIG. 3 is a plan view showing the structure of the main electrode pair of the present invention.
In the screen region E1, the transparent conductive films 41 of the sustain electrodes X and Y are linear strips having a constant width (for example, 300 μm) and are parallel to each other. The dimension D1 of the surface discharge gap g is constant over the entire length of the line. On the other hand, the width W of the metal film 41 changes along the line direction. In PDP 1, the thickness gradually increases from the power supply side connected to drive unit 80 toward the opposite side. For example, when the screen is 42 inches in size, the line length is about 960 mm, the width W is about 100 μm on the power supply side, and about 150 μm on the opposite side. Each metal film 42 is disposed on the transparent conductive film 41 so as to be close to the edge far from the surface discharge gap g. In each metal film 42, the edge far from the surface discharge gap g is parallel to the transparent conductive film 41, and the edge near the surface discharge gap g is slightly inclined with respect to the line direction. The edges near the surface discharge gap g in the pair of metal films 42 are parallel to each other. That is, the distance D2 between the metal films 42 is constant over the entire length of the line, and the aperture ratio of the cells in the line is uniform.
[0020]
Here, assuming that the minimum value of the width W of the metal film 42 is the conventional width w, the plane area of the metal film 42 is increased by the amount by which the width W gradually increases, and the entire sustain electrodes X and Y are increased. Resistance will decrease. Further, since the width W of the metal film 42 of the sustain electrode Y increases as the distance from the power supply side increases, the transition from the counter discharge with the address electrode A to the surface discharge with the sustain electrode X in the addressing is from the power supply side. A distant cell occurs in the same manner as a cell close to the power supply side, and addressing reliability is increased.
[0021]
FIG. 4 is a view showing a modification of the main electrode pair structure.
In the example of FIG. 4, the sustain electrodes Xb and Yb have a substantially linear strip-shaped transparent conductive film 41b in which the edge on the side close to the surface discharge gap g ′ is patterned stepwise so that the width changes in cell units, It consists of a metal film 42b patterned so as to become gradually thinner from the power supply side to the opposite side. Since the width D1i (i is a cell number) of the surface discharge gap g ′ is slightly different for each cell, the discharge start timing is slightly shifted between cells when a plurality of cells are turned on, and the temporal concentration of the discharge current is alleviated. The Voltage drop is reduced by reducing the peak value of the discharge current. Note that it is only necessary that the discharge start timing is appropriately non-uniform, and the width D1i of the surface discharge gap g ′ in all the cells does not have to be different from each other.
[0022]
In the case of the structure shown in FIG. 4, a stepped pulse whose peak value increases stepwise is effective as a sustain pulse that is alternately applied to the sustain electrodes Xb and Yb in order to generate a surface discharge. In a cell where discharge is likely to occur, discharge occurs when the peak value is small. When the discharge occurs, the effective voltage decreases due to charging of the wall charges, and therefore no discharge occurs even if the peak value increases thereafter. Even in a cell in which no discharge has occurred, discharge occurs at the stage where the peak value has increased. That is, by using stepped pulses, even if the discharge start condition is intentionally non-uniform in order to reduce voltage drop, surface discharge can be reliably generated in all cells.
[0023]
According to the above-described embodiment, the width W of the metal films 42 and 42b is changed so that the edges near the surface discharge gaps g and g ′ in the metal films 42 and 42b are inclined with respect to the line direction. Therefore, the shape of the opening part of each cell becomes substantially equal. The width W can be changed while keeping the distance between the metal films constant by making the edges close to the surface discharge gaps g and g 'parallel to each other and making the edges on the far side oblique. In that case, the shape of the opening of the cell is greatly different between the end and the center of the line.
[0024]
【The invention's effect】
According to the first to third aspects of the invention, voltage drop can be reduced while ensuring the uniformity of the cell aperture ratio.
[Brief description of the drawings]
FIG. 1 is a block diagram of a plasma display device according to the present invention.
FIG. 2 is a perspective view showing an internal structure of a PDP according to the present invention.
FIG. 3 is a plan view showing the structure of the main electrode pair of the present invention.
FIG. 4 is a view showing a modification of the main electrode pair structure.
FIG. 5 is a plan view showing a structure of a main electrode pair of a conventional surface discharge type PDP.
[Explanation of symbols]
1 PDP (matrix display device)
11 Glass substrate (front side substrate)
30 Discharge space 41, 41b Transparent conductive film 42, 42b Metal film D1 Distance between transparent conductive films D2 Distance between metal films g, g 'Surface discharge gap L Line W Width X, Y Sustain electrode (main electrode)

Claims (3)

On the inner surface of the front substrate in the pair of substrates sandwiching the discharge space, a pair of strip electrodes are arranged for each matrix display line, and each electrode is a plasma display panel composed of a transparent conductive film and a metal film,
Within the screen region, the width of the metal film of one electrode of each line gradually decreases from one end to the other in the line direction, and conversely the width of the metal film of the other electrode gradually increases. The plasma display panel is characterized in that the distance between the metal films of the pair of electrodes is constant regardless of the position in the line direction. Edges on the side far from the surface discharge gap in the transparent conductive film and the metal film that constitute each main electrode are substantially parallel, and the metal film is moved to the side far from the surface discharge gap and the transparent conductive film The plasma display panel according to claim 1, wherein the plasma display panel is overlapped with the film. The distance between the transparent conductive films of the pair of electrodes is made nonuniform in the line direction by changing the width of at least one transparent conductive film in each line in each line. Plasma display panel.

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