JP3010658B2 - Plasma display panel and driving method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a plasma display panel for displaying information and displaying television.

[Conventional technology]

The plasma display panel performs light emission display using gas discharge, and has excellent features such as high non-linearity and high-speed response of discharge characteristics, and furthermore, has a memory property. Attention has been paid to realizing large flat displays. Already, a large number of monochromatic plasma displays using Ne-red-orange emission have been used in laptop computers and the like, and next, colorization is strongly desired. The color light emission of the plasma display generates ultraviolet rays by the discharge gas mixed with Xe, and the red light is emitted by the phosphor applied on the inner surface of the discharge cell.
It can be performed by converting into visible light such as green or blue. In such a color plasma display panel, a so-called surface discharge type structure in which a discharge electrode and a phosphor surface are formed on a substrate facing each other is excellent because the plasma damage of the phosphor becomes a problem.

FIG. 5 shows the structure of a discharge light emitting cell of a typical surface discharge type color plasma display panel. The color plasma display panel has a structure in which a large number of these discharge light emitting cells are arranged vertically and horizontally. A first discharge electrode 52 and a second discharge electrode 53 are formed on a first glass substrate 1 to form a pair of surface discharge electrodes. The dielectric layers 6 cover these discharge electrodes. On the other hand, on the second glass substrate 9, a phosphor layer 8 coated with a phosphor powder is formed. Reference numeral 7 denotes a partition for separating the discharge cell from the adjacent discharge cell and maintaining the distance between the glass substrates. For example, a mixed gas of He and Xe is sealed as a discharge gas, and discharge is performed by applying an AC voltage to the surface discharge electrodes 52 and 53. This discharge generates ultraviolet light and causes the phosphor to emit light. As can be seen from the figure, since the phosphor layer 8 is far from the discharge region between the surface discharge electrodes, the phosphor is less deteriorated.

In the panel having the structure shown in FIG. 5, the discharge electrodes 53 are connected to the orthogonal electrodes 4 provided below the insulating layer 5 and form a matrix with the discharge electrodes 53. In addition to such a matrix configuration, a so-called one-pixel three-electrode configuration is often employed in the surface discharge type. In this method, an orthogonal electrode is formed above or below a surface discharge electrode or on a front glass substrate while being electrically insulated from the surface discharge electrode. Sustain discharge is performed by a pair of surface discharge electrodes extending in parallel, and display writing is performed by orthogonal electrodes.

[Problems to be solved by the invention]

The structure of the discharge light emitting cells of the above-described DC driven surface discharge type color plasma display panel is relatively simple,
Although it is excellent in terms of life, luminous efficiency is insufficient,
It has not yet been put to practical use. Further, in the case of a plasma display panel of a DC drive type, although there is a problem in luminance and life, gradation display can be performed relatively easily by changing the width of a drive pulse. On the other hand, in the AC drive type, the gray scale display cannot be performed by a simple method because of the discharge characteristic in which the discharge is self-stopped regardless of the pulse width.

An object of the present invention is to realize an improvement in luminous efficiency and a gradation display by a simple method without impairing the advantages of the AC-driven surface discharge type color plasma display panel.

[Means for Solving the Problems] The gist of the present invention for solving the above problems is as follows.
It has a discharge gas space, two insulating substrates sandwiching the discharge gas space, and a partition separating the discharge gas space and separating pixels from each other. The surface of one of the insulating substrates is covered with a dielectric layer. In a surface-discharge type plasma display panel having a pair of surface-discharge electrodes formed for a light-emitting display, the surface-discharge electrodes are composed of a plurality of electrode groups divided in a direction perpendicular to a direction opposite to each other. The plasma display panel having the above structure is further applied to the plasma display panel having the above structure, and by applying the address of the write palace in which the pulse width and the voltage are changed in accordance with the display tone, the divided electrode group is formed. By causing only a predetermined number of electrodes to discharge, gray scale display is realized.

[Action]

As described above, the luminous efficiency was improved by dividing a generally used surface discharge electrode into small pieces. The cause of this is not clear, but may be due to multiple effects. One is an effect due to the fact that the width of the surface discharge electrodes arranged in parallel to each other becomes narrower. A pair of surface-discharge electrodes with a constant gap between the surface-discharge electrodes and a variable electrode width was fabricated, and the luminous efficiency by surface-discharge was measured using a 200 torr He-Xe (2%) mixed gas as the discharge gas. As a result, the electrode width was reduced and the luminous efficiency was increased.
This is considered to be due to the following reasons. An electric field is effectively applied to the discharge space at the beginning of the discharge caused by voltage application, and Xe is excited at a high rate.However, as the discharge progresses, the number of ions and electrons increases and the space charge density increases. Then, the electric field in the discharge space becomes weaker. Furthermore, electric charges in the discharge space are further weakened because charges opposite to the polarity of the electrodes are accumulated as wall charges on the surface of the dielectric layer on each electrode. For this reason, the energy of the electrons becomes small, and Xe cannot be efficiently excited. Although the discharge current flows, the luminous efficiency is significantly reduced. When the electrode width is narrow, the charged particles are diffused because the region having a high space charge density is narrow, and the decrease in the Xe excitation efficiency accompanying the progress of the discharge is considered to be reduced. When the electrode width is reduced, the luminous efficiency is improved, but the discharge current is also reduced, so that the luminous brightness itself is reduced. For this reason, the use of a plurality of thin electrodes of the present invention can prevent a decrease in light emission luminance. Also,
In addition to this, it is considered that a mechanism for positively improving the excitation efficiency is working by using a plurality of electrode groups.

FIG. 4 shows a simplified cross section of one cell of the plasma display panel of the present invention divided into two electrodes. On the first glass substrate 1, two surface discharge electrodes A1, A2 and B1, B2 are formed. The electrodes A1 and A2 are connected inside or outside the panel and have the same potential. The same applies to the electrodes B1 and B2. Fig. 4 shows the structure of the A electrode with the B electrode (general term for the electrodes B1 and B2).
The figure shows a state after a voltage is applied to the electrodes (general term of the electrodes A1 and A2) with a negative polarity, and firstly after an initial state in which a discharge occurs between the electrodes A1 and B1. Many charged particles are generated in the discharge space between the electrodes A1 and B1, and positive wall charges are formed on the electrode A1, and negative wall charges are formed on the electrode B1. In this state, Xe cannot be effectively excited, but the wall charges on the outer electrodes A2 and B2 are small, and the space charge in the outer space between the electrodes A1 and B1 is also low density. is there. Therefore, it is considered that the electric field is effectively applied to the charged particles in the central portion by the contribution of the electrodes A2 and B2, and it is possible to efficiently excite Xe.

As can be understood from the above description, when the applied voltage is low or the applied pulse width is short, discharging is performed only by the electrodes A1 and B1, and the applied voltage is increased, but by increasing the pulse width, the electrodes A2 and Discharge also occurs in B2. By setting the voltage and pulse width of the sustain pulse to appropriate levels, the A1, B1 electrode discharge state and the A1, A2, B1, B2 electrode discharge state can be maintained, and gradation display is easily realized. You. By increasing the number of electrode divisions by this method, the number of display gradations can be increased. However, from the operating margin, about five adjustments with four divided electrodes are practical.

〔Example〕

An embodiment of the present invention will be described with reference to FIG. FIG. 1 is an exploded structural view of a discharge light emitting cell for one pixel of a color plasma display panel. Al on the first glass substrate 1
After arranging the orthogonal electrodes 4 made of a film,
A glass layer having a thickness of μm was formed. The divided first surface discharge electrode 2 and the divided second surface discharge electrode 3 are formed thereon. The surface discharge electrodes 3 are connected to the orthogonal electrodes 4 by through holes formed in the insulating layer 5. The divided first surface discharge electrodes 2 are also electrically connected to each other at a portion where the later-described partition overlaps. A dielectric layer 6 composed of a 5 μm thick Al ₂ O ₃ curtain and a 2 μm thick MgO film is formed to cover these surface discharge electrodes. As the other substrate, a second glass substrate 9 on which the phosphor layer 8 was formed was used. (Y, Gd) BO ₃ : Eu for red and green
Zn ₂ SiO ₄ : Mn and BaMgAl ₁₄ O ₂₃ : Eu for blue color are separately applied to each pixel. A partition 7 for partitioning pixels is formed between these two substrates. The partition wall 7 can be manufactured by a thick film method using a dielectric paste. In this embodiment, a glass plate having a thickness of 0.13 mm is etched and used as a center sheet. After assembling the panel with such a structure and exhausting it, discharge gas of He-Xe (2%) for 200 torr.
r Enclosed to form a color plasma display panel.
Here, the inner size of the partition is 0.6 mm x 0.6 mm and the height is 0.13 mm
It is. The surface discharge electrode is made of an Al film having a thickness of 0.3 μm, and is divided into three. The width of one divided electrode was 50 μm, and the space between the divided electrodes was also 50 μm. The gap between the edges of the innermost electrodes a1 and b1 is 0.1 mm. As a result of applying a 25 kHz AC voltage to this panel, a luminance of 150 cd / m ² was obtained with a white luminous efficiency of 0.5 lm / w. Although the surface discharge emission luminance electrode in a conventional structure in which the width 0.25mm not break were similar and about 150 cd / m ^2, luminous efficiency was as low as 0.3lm / w, the effect of the present invention has been confirmed Was.

As a result of producing and evaluating a color display panel in which the method of dividing the surface discharge electrode is variously changed, the width of the divided electrode is preferably about 10 μm to 150 μm. At 10 μm or less, a sharp increase in the discharge start voltage was observed, and at an electrode width exceeding 150 μm, the effect of improving the efficiency was small. The space between the divided electrodes is preferably 20 μm or more. If it is smaller than this, the effect of improving efficiency is small. The width of each divided electrode or space need not be the same. The effect of such high efficiency is the same in the case of a surface discharge type having a three-electrode configuration for one pixel.

Next, an embodiment driven by gradation display will be described. The panels used are those shown in FIG. The drive voltage waveform shown in FIG. 2 was applied between the surface discharge electrodes. An erase pulse and a write pulse having a narrow width of about 1 μs are inserted between alternating sustain pulses applied continuously at a constant period. The write pulse is not applied when not lit,
Three pulse widths are selected according to the gradation data of the lighting display. In this embodiment, the pulse width is 1.3 μs and 1.9 μ, respectively.
s and 3 μs. In the longest pulse width, the electrodes a1 to a3, b1
Discharge occurs at all divided electrodes from b3 to b3, but discharge occurs only at electrodes a1 and b1 at the shortest pulse width, and discharge occurs only at electrodes a1 and b1 at the second pulse width. This state continues even during discharge. As a result, display of four gradations including the non-lighting state can be performed.

Further, by modulating the voltage of the write pulse as shown in FIG. 3, similar gradation display could be performed.

〔The invention's effect〕

The AC-driven surface discharge type plasma display panel of the present invention can improve the luminous efficiency without increasing the cost only by slightly changing the shape of the surface discharge electrodes. Further, in the AC drive type, gray scale display can be realized only by a complicated driving method, but in the present invention, gray scale display can be performed by simple modulation of a write pulse.

[Brief description of the drawings]

FIG. 1 is a view showing a structure of a plasma display panel having divided surface discharge electrodes according to the present invention. Second
FIG. 3 is a diagram showing a drive voltage waveform for performing gradation display. FIG. 4 is a diagram for explaining the operation of the present invention. FIG. 5 is a structural view of a conventional surface discharge type plasma display panel. DESCRIPTION OF SYMBOLS 1 ... 1st glass substrate, 2 ... Divided 1st surface discharge electrode, 3 ... Divided 2nd surface discharge electrode, 4 ... Orthogonal electrode, 5 ... Insulating layer, 6 ... Dielectric Body layer, 7 ... partition wall, 8
... phosphor layer, 9 ... second glass substrate, 52 ... first surface discharge electrode, 53 ... second surface discharge electrode.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H01J 11/00-11/02 G09G 3/28

Claims (2)

(57) [Claims] A discharge gas space, two insulating substrates sandwiching the discharge gas space, and a partition separating the discharge gas space and separating pixels from each other; In a surface-discharge type plasma display panel in which a pair of surface-discharge electrodes covered with a dielectric layer are formed, the surface-discharge electrodes are each divided in a direction perpendicular to the opposite direction, and the divided individual electrodes are identical. A plasma display panel comprising a plurality of electrode groups arranged on a substrate surface, wherein individual electrodes constituting the electrode groups are electrically connected to each other for each electrode group. 2. A memory drive system in which a constant sustain pulse is applied to a surface discharge electrode of a plasma display panel according to claim 1 and is addressed by a write pulse. Controls the pulse width and voltage of a writing pulse applied to a surface discharge electrode composed of a pair of electrodes electrically connected to each other for each electrode group. A method for driving a plasma display panel, comprising: causing only a predetermined number of electrodes to discharge.