KR20080102416A - Plasma display panel and front plate thereof - Google Patents

Abstract

A plasma display panel comprising magnesium oxide film (18) covering electrodes (X,Y) and exposed to discharge gas space (31). The magnesium oxide film (18) contains silicon and calcium as impurities, and the content of impurities in the magnesium oxide film (18) is in the range of 800 to 2050 wt.ppm. By controlling the total amount of silicon and calcium in the film at 800 to 2050 wt.ppm, the discharge starting voltage can be dropped by 20 volts or more.

Description

Plasma display panel and its front panel {PLASMA DISPLAY PANEL AND FRONT PLATE THEREOF}

TECHNICAL FIELD The present invention relates to a plasma display panel having a magnesium oxide film covering an electrode, and more particularly, to an improvement of a magnesium oxide film.

AC type plasma display panels have an insulator covering the electrodes. The insulator is composed of a dielectric layer having a thickness of about 10 to 50 μm and a protective film having a thickness of about 0.5 to 1 μm stacked thereon. The dielectric layer is a layer for charging a sufficient amount of wall charge. The protective film is made of a material having excellent sputter resistance, and prevents deterioration of the dielectric layer due to ion collision during discharge.

In general, the protective film is made of magnesium oxide (MgO: magnesia). Since magnesium oxide is a high γ material, the protective film made of magnesium oxide has a property of easily emitting secondary electrons. The discharge start voltage is lowered by the emission of secondary electrons, and the driving voltage margin is expanded.

As described above, regarding the composition of the protective film that affects the discharge characteristics, a report that a magnesium oxide film containing silicon (Si) at a ratio of 500 to 10,000 ppm is effective for reducing the incidence of display defects called black noise is made in Japanese Patent. It is in the publication 3247632.

In Japanese Unexamined Patent Publication No. 2003-109511, as a means for improving the discharge characteristics, silicon oxide film is contained in a ratio of 500 to 15000 ppm, and other impurities such as potassium (K), calcium (Ca) and iron ( It is proposed to make content of Fe) and chromium (Cr) as small as possible.

On the other hand, Japanese Unexamined Patent Application Publication No. 2005-340206 proposes doping calcium, aluminum (Al) and silicon into a magnesium oxide film. As preferable doping amount, Ca: 100-300ppm, Al: 60-90ppm, Fe: 60-90ppm, Si: 40-100ppm are disclosed.

Patent Document 1: Japanese Patent No. 3247632

Patent Document 2: Japanese Patent Laid-Open No. 2003-109511

Patent Document 3: Japanese Patent Laid-Open No. 2005-340206

<Start of invention>

As a problem related to the driving of the plasma display panel, addressing speed is increased. When faster addressing is possible, more display lines can be scanned than in the developing address period, so that the screen can be made higher in resolution. In addition, instead of increasing the display line, if the sustain period is extended by the time required for the addressing to be shortened, the number of display discharges can be increased to increase the luminance.

The desired cell structure for speeding up the addressing is a structure in which address discharge miss does not occur even if the pulse width of the address pulse is shortened. The address discharge miss occurs when the discharge delay time from the application of the pulse to the start of the discharge is longer than the pulse width of the address pulse. In order to reduce the probability of occurrence of an address discharge miss, a cell in which a discharge start voltage is lower than a phenomenon and which discharge is easy to occur is needed.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a plasma display panel which is useful for improving display quality having cells which are likely to cause discharge.

As a result of examining the relationship between the impurity content (hereinafter sometimes referred to as impurity concentration) of the magnesium oxide film and the discharge characteristic, it is compared with other cases in the case of containing silicon and calcium as impurities and the total of these contents in the range of 800 to 2050 ppm. It turned out that the discharge characteristic is favorable. The present invention is based on this fact.

A plasma display panel which achieves the above object has a magnesium oxide film which covers the electrode and is exposed to the discharge gas space. The magnesium oxide film contains silicon and calcium as impurities, and the content of the impurities in the magnesium oxide film is 800 to 2050 ppm. [Ppm] which is a unit of content in this specification is [weight ppm] in detail.

1 is an exploded perspective view showing an example of a cell structure of a plasma display panel according to the present invention;

2 is a graph showing the relationship between the sum total of the contents of silicon and calcium and the discharge characteristics;

3 is a graph showing the relationship between calcium content and discharge characteristics.

4 is a graph showing the relationship between the content of silicon and discharge characteristics.

<Best Mode for Carrying Out the Invention>

The present invention can be applied to various plasma display panels having a magnesium oxide film related to discharge. The plasma display panel 1 shown in FIG. 1 is an example.

The plasma display panel 1 includes a front plate 10 and a back plate 20. In the figure, the front plate 10 and the back plate 20 are shown separated from each other for easy understanding of the internal structure, but in reality they abut. The front plate 10 includes a glass substrate 11, a display electrode X as a first electrode, a display electrode Y as a second electrode, a dielectric layer 17 for AC driving, and a magnesium oxide as a protective film for preventing sputtering of the dielectric layer 17. Film 18 is provided. The back plate 20 includes a glass substrate 21, an address electrode A serving as a third electrode, a dielectric layer 22, a plurality of partitions 23, phosphors 27 of red (R), phosphors of green (G) 28, and the like. ) And blue (B) phosphor 29.

In the front plate 10, the display electrodes X and the display electrodes Y are alternately arranged at equal intervals on the inner surface of the glass substrate 11. All electrode gaps in this arrangement are surface discharge gaps, and adjacent display electrodes X and display electrodes Y constitute electrode pairs for surface discharge. Each of these display electrodes is composed of a transparent conductive film 13 patterned in a thick band shape and a metal film (bus conductor) 15 patterned in a thin band shape. In addition, as another example of the display electrode array, there is a form in which an independently controllable electrode pair is associated with each row of the matrix display. The dielectric layer 17 covering the display electrode X and the display electrode Y is a low-melting-point glass layer having a thickness of about 30 μm spreading over the entire screen. Details of the magnesium oxide film 18 will be described later.

In the back plate 20, the address electrodes A are arranged at the same pitch as the cell arrangement pitch, and intersect with the display electrode X and the display electrode Y. These address electrodes A and the display electrode Y of the front plate 10 constitute an electrode matrix for cell selection by address discharge. The partition 29 is disposed in the electrode gap of the address electrode array. The partition 29 divides the discharge gas space for each column of the matrix display, and a column space 31 corresponding to each column is formed. The phosphor layers 27, 28, and 29 are disposed to cover the surface of the dielectric layer 22 and the side surfaces of the partition walls 23, and are excited and emitted by ultraviolet rays emitted by the discharge gas.

In the plasma display panel 1 having the above-described configuration, the front panel 10 and the back plate 20 are bonded to each other, and the peripheral portions of the front plate 10 and the back plate 20 are joined by a sealing material. And the step of evacuating the gas remaining in the internal space formed by the bonding, and the process of filling the discharge gas into the internal space cleaned by the exhaust.

In manufacturing the front plate 10, the magnesium oxide film 18 is formed by a vacuum deposition method. Vacuum deposition is industrially well-suited and suitable for mass production. Vacuum vapor deposition here includes vapor deposition which uses ion plating together.

Hereinafter, the impurity concentration of the magnesium oxide film 18 according to the features of the present invention will be described.

As samples for evaluating the discharge characteristics, a plurality of plasma display panels (hereinafter referred to as characteristic samples) having the same configuration except that the impurity concentrations of the magnesium oxide film 18 were different were manufactured. Prior to the formation of each magnesium oxide film 18 of these characteristic samples, a powder in which silicon oxide and calcium oxide were added to a high purity magnesium oxide powder of at least 99.95% was sintered into pellets. In this way, a plurality of vapor deposition materials having different amounts of oxides were prepared. Using these vapor deposition materials, a magnesium oxide film having a thickness of about 800 nm was formed by a reactive electron beam vapor deposition method.

The range of film formation conditions is as follows.

Deposition pressure: 0.005 to 0.15 kPa

Substrate temperature: 100-300 degreeC

Reaction gas: Oxygen

The drive circuit was connected to the produced characteristic sample, and the test which displays the test pattern was done. The test pattern is a monochromatic stripe pattern with a sufficiently wide line spacing that emits 1/3 of the cells of the selected display line. The drive sequence includes addressing and sustain following it. In addressing, an address pulse is applied between the display electrode Y of the cell to emit light and the electrode of the address electrode Y, thereby causing an address discharge for forming wall charges. In the sustain, a sustain pulse is applied between the display electrodes X of all the cells and the electrodes of the display electrodes Y. The sustain pulse generates display discharges only in cells in which wall charges are correctly formed in addressing. If no address discharge miss occurs, the test pattern is correctly displayed in the sustain.

In the test, the peak value of the address pulse was gradually raised, and the peak value at which all cells to emit light emitted light was recorded as the discharge start voltage of the address discharge. The same test was done multiple times about each characteristic sample, and the average value of these results was made into the measured value.

After the test, each characteristic sample was decomposed and a small piece having a size of 10 mm x 10 mm was cut out from the central portion of the front plate as a sample for evaluating impurity concentration (hereinafter referred to as concentration sample).

The impurity concentration of the magnesium oxide film 18 of the concentration sample was measured by a secondary ion mass spectrometer.

The test and measurement resulted in the results shown in FIG. 2. The horizontal axis of the graph of FIG. 2 corresponds to the sum (concentration total amount) of the concentrations of silicon and calcium as impurities, and the vertical axis corresponds to the difference between the discharge start voltage and the comparative example. The comparative example here is a plasma display panel having a magnesium oxide film to which impurities formed by using a vapor deposition material made of the above high purity magnesium oxide powder are not added.

In Fig. 2, for example, the discharge start voltage when the total amount of impurities is 800 ppm is about 23 volts lower than that of the comparative example. 2 shows that by controlling the total amount of impurities to 800 to 2050 ppm, a remarkable improvement effect of the discharge characteristics such that the discharge start voltage is lowered by 20 volts or more is obtained.

3 shows the relationship between the concentration and the discharge start voltage when the silicon concentration is 490 ppm and the calcium concentration is changed in the range of 10 to 1000 ppm. The discharge start voltage is about 10 volts lower when the calcium concentration is 10 ppm or more when the calcium concentration is 10 ppm or more. In FIG. 3, it is understood that addition of an amount of calcium or more is required in order to improve discharge characteristics.

Fig. 4 shows the relationship between the concentration and the discharge start voltage when the calcium concentration is 500 ppm and the silicon concentration is changed in the range of about 250 to 1100 ppm. From FIG. 4, it can be seen that by controlling the silicon concentration to 400 to 1050 ppm, a remarkable improvement effect of the discharge characteristics such that the discharge start voltage is lowered by 20 volts or more is obtained. When the silicon concentration is 400 ppm or less and 1050 ppm or more, a sufficient improvement effect is not obtained.

In the above embodiment, the configuration of the plasma display panel 1 can be appropriately changed within the scope of the present invention. The thickness of the magnesium oxide film 18 is 500 nm or more, for example, 500-1000 nm. The dielectric layer 17 is not limited to calcined glass, and may be a vapor phase growth film. Instead of the partition 23, a partition of a mesh pattern can be employed.

This invention contributes to the improvement of the performance of a plasma display panel.

Claims (5)

A plasma display panel having a magnesium oxide film covering an electrode and exposed to a discharge gas space, And said magnesium oxide film contains silicon and calcium as impurities and has an impurity content of 800 to 2050 ppm. The method of claim 1, A plasma display panel having a calcium content of 400 to 1000 ppm in the magnesium oxide film. The method of claim 1, A plasma display panel, wherein the content of silicon in the magnesium oxide film is 400 to 1050 ppm. The method of claim 1, And said magnesium oxide film is a vacuum deposition film. As the front panel of the plasma display panel, A glass substrate, an electrode arranged on the glass substrate, a dielectric layer covering the electrode, and a magnesium oxide film laminated on the dielectric layer, The magnesium oxide film contains silicon and calcium, the silicon content is 400-1050ppm, and the calcium content is 400-1000ppm.

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