JP2004071434A - Plasma display panel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-definition plasma display panel capable of maintaining brightness almost constant even after a long time of use. <P>SOLUTION: With the plasma display panel 1 provided with two boards 10, 20 set in opposition with a given interval, partition walls 30 partitioning spaces between the boards 10, 20 in the plural number, discharge cells 31 formed by being surrounded with the partition walls 30 and the boards 10, 20, and phosphor layers 35 fitted inside the discharge cells 31, an average particle size of phosphors constituting the phosphor layers 35 is to be 0.01 to 1.0 μm, and an area ratio of the phosphor layers 35 in the discharge cells 31 is to be 10 t0 40 area percent. <P>COPYRIGHT: (C)2004,JPO

Description

【０１３５】
表１から明らかなように、比較例１の輝度劣化率が−９．７％であるのに対して、ＰＤＰ１−１の輝度劣化率は−１．５％、ＰＤＰ１−２の輝度劣化率は−１．１％と、比較例１に対して本発明のＰＤＰの輝度劣化率は低く、２４時間継続して電圧を印加しても、初期パネル輝度とほぼ同程度の輝度を維持することができている。
【０１３６】
これは、以下の理由によると考えられる。
まず、ＰＤＰ１−１では、平均粒径が０．８μｍ又は０．７μｍの蛍光体を使用し、ＰＤＰ１−２では平均粒径が０．４μｍ又は０．３μｍの蛍光体を使用しているのに対して、比較例１では平均粒径が１．８μｍの蛍光体を使用している。放電セル内で発生する紫外線は、蛍光体の表層付近にしか進入しないため、蛍光体を微粒化することにより、蛍光体粒子体積に占める発光に寄与する体積の割合を増加することができる。これにより、同じ電圧を印加したときの、ＰＤＰの輝度を向上することができる。このため、１，０００ｃｄ／ｍ^２の初期パネル輝度を達成するために必要な電圧を、比較例に対してＰＤＰ１−１、ＰＤＰ１−２では低くすることができる。それにより、ＰＤＰ１−１、ＰＤＰ１−２は、比較例１に対して放電セル中で生じるイオン濃度を低減することができ、蛍光体をイオン衝撃から守ることができ、蛍光体の劣化を防止することができる。
【０１３７】
さらに、ＰＤＰ１−１及びＰＤＰ１−２で使用した蛍光体は液相合成法により製造したものである。これに対して比較例１で使用した蛍光体は固相合成法により製造したものである。液相合成法では、上記のように、保護コロイドの添加量や反応液の添加速度等を変化させることによって、粒径を微粒に製造することができ、蛍光体を機械的に粉砕するような工程は含まない。一方、固相合成法では、蛍光体の合成時には、ボールミルで混合する工程がある。このとき、蛍光体は粉砕され、応力が加えられることにより、結晶格子中に格子欠陥が生じる可能性が高い。このため、固相合成法により得た蛍光体は、プラズマ放電時に、イオン衝撃を受けると、劣化しやすい。一方、液相合成法ではそのような応力は一切加えられていないので、結晶格子中に格子欠陥等が生じる可能性は低い。
【０１３８】
以上より、ＰＤＰ１−１、ＰＤＰ１−２は、比較例１に対して、放電維持電圧を低くすることができ、さらにＰＤＰ１−１、ＰＤＰ１−２は、比較例１に対して劣化しにくい蛍光体を使用しているため、表１に示すように、ＰＤＰ１−１及びＰＤＰ１−２の輝度劣化率は、比較例１に対して低くなると考えられる。
【０１３９】
〔実施例２〕
次に、実施例２について説明する。実施例２では、実施例１で製造した蛍光体Ｂ−１、Ｇ−１、Ｒ−１を用いて、放電セル中に占める蛍光体層の体積の割合が異なるＰＤＰを製造し、輝度劣化率について評価した。
まず、ＰＤＰ２−１の製造について説明する。
【０１４０】
１．ＰＤＰ２−１の製造
実施例１の５（１）において、青色蛍光体ペーストＢＰ−１、緑色蛍光体ペーストＧＰ−１、赤色蛍光体ペーストＲＰ−１の量を放電セル３１の容積に対して、焼成後の蛍光体層３５が占める体積の割合が１５％になるように調整した以外は、実施例１の５（１）と同様にしてＰＤＰ２−１を製造した。
【０１４１】
２．ＰＤＰ２−２の製造
実施例１の５（１）において、青色蛍光体ペーストＢＰ−１、緑色蛍光体ペーストＧＰ−１、赤色蛍光体ペーストＲＰ−１の量を、放電セル３１の容積に対して、焼成後の蛍光体層３５が占める体積の割合が３５％になるように調整した以外は、実施例１の５（１）と同様にしてＰＤＰ２−２を製造した。
【０１４２】
〔比較例２〕
（１）蛍光体ペーストの調整
実施例１の５（１）において、青色蛍光体ペーストＢＰ−１、緑色蛍光体ペーストＧＰ−１、赤色蛍光体ペーストＲＰ−１の量を放電セル３１の容積に対して、焼成後の蛍光体層３５が占める体積の割合が６０％になるように調整した以外は、実施例１の５（１）と同様にしてＰＤＰを製造して、比較例２とした。
【０１４３】
〔評価２〕
上記で製造したＰＤＰ２−１、ＰＤＰ２−２と比較例２で製造したＰＤＰについて、評価１と同様に、初期パネル輝度が１，０００ｃｄ／ｍ^２になるような放電維持電圧（周波数３０Ｈｚ）を２４時間連続して印加して、輝度劣化率を評価した。結果を表２に示す。
【表２】

【０１４４】
表２から明らかなように、比較例２の輝度劣化率が−７．８％であるのに対して、ＰＤＰ２−１の輝度劣化率は−１．８％、ＰＤＰ２−２の輝度劣化率は−０．５％と、比較例１に対して本発明のＰＤＰの輝度劣化率は低く、２４時間継続して放電維持電圧を印加しても、初期パネル輝度とほぼ同程度の輝度を維持することができている。
【０１４５】
これは、以下の理由によると考えられる。
まず、比較例２では、放電セル中に蛍光体層が占める割合が６０％と非常に高く、放電空間が４０％となる。これに対して、ＰＤＰ２−１では放電セル中に蛍光体層が占める割合が１５％であり、放電空間は８５％も確保されている。ＰＤＰ１−２では、放電セル中に蛍光体層が占める割合は３５％であり、放電空間は６５％確保されている。比較例２では、使用している蛍光体量は、ＰＤＰ２−１、ＰＤＰ２−２と比べると多くなるが、放電空間が狭くなるため、蛍光体を励起するために十分な紫外線を発生することができず、輝度が低下する。この輝度低下を補うためには、高電圧を印加しなければならない。
【０１４６】
一方、ＰＤＰ２−１、ＰＤＰ２−２では、比較例２に比べると蛍光体付量は少ないが、放電空間が十分に確保されているため、輝度が高く、そのため、初期パネル輝度を達成するための電圧も、比較例２に比べて、小さくすることができる。よって、比較例２に対して、ＰＤＰ２−１、ＰＤＰ２−２では、放電セル中のイオン濃度を低減することができ、これにより、蛍光体がイオン衝撃を受けにくくすることができる。このため、表２に示すように、２４時間連続して電圧を印加しても、輝度劣化を低く抑えることができる。
【０１４７】
〔実施例３〕
次に、実施例３について説明する。実施例３では、実施例１で製造した蛍光体Ｂ−１、Ｇ−１、Ｒ−１を用いて、蛍光体の充填率が異なるＰＤＰを製造し、輝度劣化について評価した。
まず、ＰＤＰ３−１の製造について説明する。
【０１４８】
１．ＰＤＰ３−１の製造
（１）蛍光体ペーストの調整
実施例１の４において、各色発光蛍光体Ｂ−１、Ｇ−１、Ｒ−１の固形分濃度が２５質量％となるようにした以外は、実施例１の４と同様にして各色発光蛍光体ペーストＢＰ−１１、ＧＰ−１１、ＲＰ−１１を調整した。
【０１４９】
（２）ＰＤＰの製造
実施例１の５（１）において、上記で調整した青色蛍光体ペーストＢＰ−１１、緑色蛍光体ペーストＧＰ−１１、赤色蛍光体ペーストＲＰ−１１の量を放電セル３１の容積に対して、焼成後の蛍光体層３５が占める体積の割合が１５％になるように調整した以外は、実施例１の５（１）と同様にしてＰＤＰ３−１を製造した。また、このときの蛍光体充填率は３４．５％であった。
【０１５０】
２．ＰＤＰ３−２の製造
（１）蛍光体ペーストの調整
実施例１の４において、各色発光蛍光体Ｂ−１、Ｇ−１、Ｒ−１の固形分濃度が５０質量％となるようにした以外は、実施例１の４と同様にして各色発光蛍光体ペーストＢＰ−１２、ＧＰ−１２、ＲＰ−１２を調整した。
【０１５１】
（２）ＰＤＰの製造
実施例１の５（１）において、上記で調整した青色蛍光体ペーストＢＰ−１２、緑色蛍光体ペーストＧＰ−１２、赤色蛍光体ペーストＲＰ−１２の量を放電セル３１の容積に対して、焼成後の蛍光体層３５が占める体積の割合が１５％になるように調整した以外は、実施例１の５（１）と同様にしてＰＤＰ３−２を製造した。また、このときの蛍光体充填率は６９．０％であった。
【０１５２】
〔比較例３〕
（１）蛍光体ペーストの調整
実施例１の４において、各色発光蛍光体Ｂ−１、Ｇ−１、Ｒ−１の固形分濃度が７．５質量％となるようにした以外は、実施例１の４と同様にして各色発光蛍光体ペーストＢＰ−１３、ＧＰ−１３、ＲＰ−１３を調整した。
【０１５３】
（２）ＰＤＰの製造
実施例１の５（１）において、上記で調整した青色蛍光体ペーストＢＰ−１３、緑色蛍光体ペーストＧＰ−１３、赤色蛍光体ペーストＲＰ−１３の量を放電セル３１の容積に対して、焼成後の蛍光体層３５が占める体積の割合が５０％になるように調整した以外は、実施例１の５（１）と同様にしてＰＤＰを製造して、比較例３とした。また、このときの蛍光体充填率は１０．４％であった。
【０１５４】
〔評価３〕
上記で製造したＰＤＰ３−１、ＰＤＰ３−２と、比較例３で製造したＰＤＰについて、評価１と同様に、初期パネル輝度が１，０００ｃｄ／ｍ２になるような放電維持電圧（周波数３０Ｈｚ）を２４時間連続して印加して、輝度劣化率を評価した。結果を表３に示す。
【表３】

【０１５５】
表３から明らかなように、比較例３の輝度劣化率が−８．４％であるのに対して、ＰＤＰ３−１では−２．３％、ＰＤＰ３−２では−１．０％と低い値を示し、２４時間継続して電圧を印加しても、初期パネル輝度とほぼ同程度の輝度を維持することができている。
これは、以下の理由によると考えられる。
【０１５６】
まず、比較例３の放電セル中に蛍光体層の占める割合が５０％と高い。このため、比較例３では放電空間が放電セルに対して５０％となっている。一方、ＰＤＰ３−１、ＰＤＰ３−２では１５％であり、放電空間が８５％確保されている。
さらに、比較例３では、蛍光体層が占める割合が高いにも関わらず、ＰＤＰ３−１、ＰＤＰ３−２に比べると蛍光体の充填率が低い。比較例３の蛍光体充填率は１０．４％であり、放電セル中に蛍光体粒子が占める体積の割合を求めると、５．２％になる。一方、ＰＤＰ３−１の蛍光体充填率は、３４．５％であり、放電セル中に蛍光体粒子が占める体積の割合は、５．７５％になる。ＰＤＰ３−２の蛍光体充填率は、６９．０％であり、放電セル中に蛍光体粒子が占める体積の割合は、１０．３５％になる。
【０１５７】
このように、比較例３では、放電セル中に蛍光体粒子が占める体積の割合が少なく、さらに放電空間が小さいため、１，０００ｃｄ／ｍ^２の初期パネル輝度を達成するために必要な印加電圧も高くなる。一方、ＰＤＰ３−１では、放電セル中に蛍光体粒子が占める体積の割合が５．１２％と比較例３と同程度であるが、放電空間の割合が８５％と高い。このため、比較例３に対して、放電維持電圧を低くすることができる。ＰＤＰ３−２では、蛍光体の充填率が高いために、放電空間が８５％であることに加えて、放電セル中に蛍光体粒子が占める体積の割合が、比較例３とＰＤＰ３−１の約２倍となっている。このため、さらに放電維持電圧を低くすることができる。
【０１５８】
このため、放電セル中のイオン濃度を、ＰＤＰ３−１、ＰＤＰ３−２では、比較例３に対して、低くすることができ、蛍光体をイオン衝撃から守り、蛍光体の劣化を防止している。このため、表３に得られるように、輝度劣化率が低く、長時間継続して使用しても輝度をほぼ一定に維持することができる。
【０１５９】
【発明の効果】
本発明によれば、平均粒径が０．０１〜１．０μｍの極微粒な蛍光体を用いて蛍光体層を構成し、さらに、蛍光体層が放電セル中に占める体積の割合を１０〜４０％とすることで、放電空間を拡大し、かつ、紫外線を効率よく受光して発光効率を向上することができる。これにより、高精細化したＰＤＰであっても、輝度向上することができる。このため、従来と同程度の輝度を達成するためには、放電維持時の印加電圧を低くすることができ、蛍光体をイオン衝撃による劣化から守ることができる。したがって、長時間ＰＤＰを使用しても、輝度をほぼ一定に維持することができる。
また、蛍光体層中の蛍光体が占める体積の割合を３０〜８０％にすることによっても、同様の効果を得ることができる。
更に、蛍光体を液相合成法により製造することよって、結晶中の格子欠陥を防ぎ、劣化しにくい蛍光体とすることができる。
【図面の簡単な説明】
【図１】本発明に係るプラズマディスプレイパネルの一例を示した斜視図である。
【図２】図１に示したプラズマディスプレイパネルに設けられた電極の配置を示した概略平面図である。
【図３】本発明に係るプラズマディスプレイパネルに設けられる放電セルの構造の他の例として、格子型のセル構造を示した概略平面図である。
【図４】本発明に係るプラズマディスプレイパネルに設けられる放電セルの構造の他の例として、ハニカム型のセル構造を示した概略平面図である。
【符号の説明】
１　　プラズマディスプレイパネル
１０　前面側基板
１０ａ　画像表示面
２０　背面板側基板、一方の基板
３０、４０、５０　隔壁
３０ａ　隔壁表面
３１、４１、５１　放電セル
３１ａ　一方の基板表面
３５　蛍光体層[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a plasma display panel display device used for image display such as a television receiver, and more particularly, to a plasma display panel device having a phosphor layer which emits light when excited by ultraviolet rays.
[0002]
[Prior art]
2. Description of the Related Art A plasma display panel (hereinafter, abbreviated as PDP) has two glass substrates provided with electrodes and a large number of minute discharge spaces (hereinafter, referred to as cells) formed by partition walls provided between the substrates. ing. A phosphor that emits red (R), green (G), blue (B), or the like is applied to the side surfaces of the partition walls surrounding each cell and the bottom surface of the cell, and a discharge gas containing Xe, Ne, or the like as a main component. Is enclosed. When a voltage is applied between the electrodes to selectively discharge them, ultraviolet rays are generated, and the phosphor is excited to emit light, whereby desired information can be displayed.
[0003]
Generally, the particle size of a phosphor used for a PDP is about 2 to 10 μm, and is mainly manufactured by a solid phase synthesis method. The solid phase synthesis method is a method in which a predetermined amount of a compound containing an element constituting a phosphor matrix and a compound containing an activator element are mixed and fired at a predetermined temperature to obtain a phosphor by a solid-phase reaction.
[0004]
[Problems to be solved by the invention]
In recent years, PDPs have tended to have higher definition, and accordingly, cells have been miniaturized. However, when the cell is miniaturized, the amount of the phosphor that can be applied in the cell decreases, and the amount of the phosphor involved in light emission itself decreases. Further, the discharge space is narrowed by the miniaturization of the cell, and it is not possible to generate ultraviolet rays sufficient to excite the phosphor. For this reason, the brightness decreases. Therefore, the voltage applied to maintain the plasma discharge is increased to increase the amount of generated ultraviolet light, thereby improving the luminance.
[0005]
By the way, in the conventional solid phase synthesis method, a phosphor having a desired particle size is manufactured by repeatedly performing a solid phase reaction and a pulverizing step. However, in the pulverizing step, stress is applied to the phosphor particles, and there is a possibility that a lattice defect occurs in the crystal lattice. As described above, when the applied voltage at the time of plasma discharge is increased, the ion concentration generated in the discharge space increases, and the phosphor is easily exposed to ion bombardment. When the phosphor is subjected to ion bombardment, crystallinity is reduced and luminous efficiency is reduced (this is referred to as deterioration of the phosphor). Phosphors having lattice defects in the crystal lattice are more likely to be degraded than those without lattice defects. For this reason, conventionally, when plasma discharge is continued, there has been a problem that the phosphor deteriorates with time, and accordingly, the luminance also decreases.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a high-definition plasma panel display that can prevent deterioration of a phosphor and thereby maintain luminance substantially constant even when used for a long time.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention according to claim 1 includes two substrates disposed to face each other at a predetermined interval, a partition provided between the substrates and dividing a space between the substrates into a plurality of partitions, In a plasma display panel including a discharge cell formed by being surrounded by the partition wall and the substrate, and a phosphor layer provided inside the discharge cell, an average particle diameter of a phosphor constituting the phosphor layer Is 0.01 to 1.0 μm, and a ratio of a volume occupied by the phosphor layer in the discharge cells is 10 to 40% by volume.
[0007]
Here, the average particle diameter of the phosphor is obtained by measuring the average particle diameter of 300 phosphor particles in the phosphor layer using an electron microscope (for example, S-900, manufactured by Hitachi, Ltd.). Value. In addition, when the phosphor particles are so-called normal crystals having a cubic or octahedral shape, the particle size refers to the length of the edge of the phosphor particles. In the case where the phosphor particles are not normal crystals, for example, when the phosphor particles are spherical, rod-shaped, or tabular particles, the diameter refers to a sphere equivalent to the volume of the phosphor particles.
[0008]
According to the first aspect of the present invention, since the ratio of the phosphor layer in the discharge cell is 10 to 40% by volume, the ratio of the discharge space in the discharge cell is 90 to 60% by volume. For this reason, even if the discharge cells are miniaturized, a discharge space is ensured, so that ultraviolet rays sufficient to excite the phosphor can be generated. Therefore, it is not necessary to increase the discharge sustaining voltage in order to secure luminance.
[0009]
In the prior art, the phosphor layer was formed using a phosphor having an average particle diameter of 2 to 10 μm, whereas in the present invention, an extremely fine phosphor having an average particle diameter of 0.01 to 1.0 μm was used. From the phosphor layer. Usually, ultraviolet rays generated in the discharge cells during discharge enter only near the surface of the phosphor, for example, only about 100 nm. For this reason, for example, in the case of a 2 μm phosphor, the volume of the portion contributing to light emission is only about 18% of the volume of the phosphor particles. Therefore, by making the phosphor finer as in the present invention, the ratio of the volume of the phosphor particles that contributes to light emission can be increased. As a result, it is possible to more efficiently receive ultraviolet rays and improve the emission intensity as compared with the related art.
[0010]
As described above, even in a high-definition PDP in which the discharge cells are miniaturized, the luminance can be improved as compared with the related art. Conversely, in order to achieve the same level of brightness as in the prior art, the voltage applied to maintain the plasma discharge can be reduced. Therefore, the concentration of ions generated in the discharge cell during plasma discharge can be reduced, and the phosphor can be prevented from being deteriorated by being exposed to ion bombardment. As a result, even if the PDP is used continuously for a long time, the luminance can be maintained substantially constant.
[0011]
According to a second aspect of the present invention, in the plasma display panel according to the first aspect, a ratio of a volume of the phosphor layer in the discharge cell is 10 to 30% by volume.
[0012]
According to the second aspect of the present invention, since the ratio of the volume of the phosphor layer in the discharge cell is 10 to 30%, the ratio of the discharge space during plasma discharge can be as high as 90 to 70%. As a result, ultraviolet light for exciting the phosphor can be more sufficiently generated, and the luminance can be further improved. This makes it possible to further reduce the voltage required to achieve the same level of luminance as in the past. Therefore, the deterioration of the phosphor can be prevented, and the luminance can be maintained substantially constant even when the PDP is used for a long time.
[0013]
According to a third aspect of the present invention, in the plasma display panel according to the first or second aspect, the surface of the partition wall facing the inside of the discharge cell and the surface of one of the substrates are covered with a phosphor layer. When the phosphor layer can be used, the amount of the phosphor constituting the phosphor layer is 20 g / m per unit area of the phosphor layer coverable surface. ² Above, 100 g / m ² A plasma display panel characterized by the following.
[0014]
According to the third aspect of the present invention, the fine particle phosphor having an average particle diameter of 0.01 to 1.0 μm is 20 g / m 2 per unit area of the phosphor-coverable surface. ² Above, 100 g / m ² By using in the following range, the ratio of the volume occupied by the phosphor layer in the discharge cell can be set to 10 to 40% by volume.
[0015]
According to a fourth aspect of the present invention, there are provided two substrates which are arranged to face each other at a predetermined interval, a partition provided between the substrates to partition a space between the substrates into a plurality, and the partition and the substrate surround the partition. In a plasma display panel including a discharge cell formed as described above and a phosphor layer provided inside the discharge cell, the phosphor constituting the phosphor layer has an average particle size of 0.01 to 1.0 μm. Wherein the ratio of the volume occupied by the phosphor in the phosphor layer is 30 to 80% by volume.
[0016]
According to the fourth aspect of the present invention, since the phosphor layer is formed using the phosphor having an average particle diameter of 0.01 to 1.0 μm, the phosphor is efficiently filled in the phosphor layer. be able to. On the other hand, conventionally, a phosphor having an average particle size of 2 to 10 μm has been used. Therefore, when a phosphor layer is filled with a phosphor, a large gap is generated, and if the particle size varies, an irregular shape is formed. There was a possibility that a gap might occur. For this reason, it is difficult to make the ratio of the volume occupied by the phosphor in the phosphor layer 30 to 80% by volume, and in order to secure a necessary phosphor amount, the phosphor layer in the discharge cell occupies. It was necessary to increase the volume ratio. However, in the present invention, the phosphor layer can be efficiently filled with the fine particle phosphor, so that the ratio of the volume of the phosphor layer occupying in the discharge cells can be reduced, and the discharge space can be reduced as compared with the conventional case. Can be widened. Therefore, luminance can be improved.
[0017]
Further, in the present invention, the phosphor layer is composed of extremely fine phosphor having an average particle diameter of 0.01 to 1.0 μm. As described above, since the ultraviolet rays generated in the discharge cells usually enter only near the surface of the phosphor particles, the phosphor is atomized to efficiently receive the ultraviolet rays and improve the emission amount. Can be.
[0018]
As described above, even in a high-definition PDP, it is possible to reduce the applied voltage necessary to achieve the same level of brightness as in the past. Your body is less susceptible to ion bombardment. Therefore, even if the PDP is used continuously for a long time, the luminance can be maintained substantially constant.
[0019]
According to a fifth aspect of the present invention, in the plasma display panel according to the fourth aspect, a ratio of a volume occupied by the phosphor in the phosphor layer is 40 to 80% by volume.
[0020]
According to the fifth aspect of the present invention, since the phosphor occupies 40 to 80% by volume in the phosphor layer, the phosphor layer is more efficiently filled with the phosphor. Therefore, the discharge space can be kept wider, and the luminance can be improved. As a result, the voltage required to maintain the discharge can be reduced, the phosphor is less likely to be exposed to ion bombardment, and luminance degradation due to long-term use of the PDP can be prevented.
[0021]
According to a sixth aspect of the present invention, in the plasma display panel according to any one of the first to fifth aspects, the phosphor is manufactured by a liquid phase synthesis method in which a phosphor raw material is reacted in a liquid phase. It is characterized by the following.
[0022]
According to the sixth aspect of the present invention, unlike the conventional solid phase synthesis method in which a solid-phase reaction is performed, a phosphor is produced by a liquid phase synthesis method in which a phosphor material is reacted in a liquid phase. Is performed between element ions constituting the phosphor. Therefore, a stoichiometrically high-purity phosphor can be easily obtained, and the luminous efficiency and the yield can be increased.
[0023]
Further, in the conventional solid phase synthesis method, since the phosphor is produced by repeatedly performing the solid-phase reaction and the pulverizing step, the particle size of the obtained phosphor is relatively large and is about 2 to 10 μm. On the other hand, in the liquid phase synthesis method, since the reaction is performed in the liquid phase as described above, the average particle size, particle shape, particle size distribution, emission characteristics, and the like of the phosphor can be more precisely controlled. Can be obtained with a narrow particle size distribution. For this reason, it is possible to increase the ratio of the volume of the phosphor particles that contributes to light emission, efficiently receive ultraviolet rays, and increase the luminous efficiency of the phosphor.
[0024]
Furthermore, in the liquid phase synthesis method, a phosphor having a small particle size and a narrow particle size distribution can be obtained, so that the phosphor can be efficiently filled in the phosphor layer. On the other hand, since the phosphor obtained by the solid phase synthesis method is pulverized in the pulverization step as described above, it is highly likely to be polyhedral, and the particle size distribution is wide. For this reason, even if a phosphor layer is formed, gaps of irregular shapes may be generated in the layer, and the phosphor cannot be efficiently filled. For this reason, even if the same amount (mass) of the phosphor is used, the ratio of the volume occupied by the phosphor layer in the discharge cell can be reduced by using the phosphor produced by the liquid phase synthesis method. . Thereby, the discharge space can be enlarged, and the luminance can be improved.
[0025]
Further, in the solid-phase synthesis method, when stress is applied to the phosphor in the pulverizing step, there is a possibility that lattice defects may occur in the crystal lattice of the phosphor. Lattice defects in the phosphor absorb the ultraviolet wavelength (147 nm) generated in the cell by the plasma discharge and hinder excitation of the emission center. For this reason, there is a possibility that the brightness may be reduced. However, as described above, in the liquid phase synthesis method, since there is no pulverizing step or the like and there is no possibility of generating lattice defects, a phosphor having high luminous efficiency can be obtained.
[0026]
Further, as described above, if there is a lattice defect in the crystal lattice of the phosphor, the crystallinity tends to be reduced starting from the lattice defect when subjected to ion bombardment, and the crystal is more likely to be degraded than a phosphor having no lattice defect. . That is, even with the same applied voltage, the phosphor manufactured by the solid phase synthesis method is easily deteriorated, and the phosphor manufactured by the liquid phase synthesis method is hardly deteriorated.
[0027]
As described above, by using a phosphor manufactured by the liquid phase synthesis method, the luminance is improved and the phosphor is hardly deteriorated. Therefore, even if the PDP is used for a long time, the deterioration of the phosphor can be surely prevented. .
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a plasma display panel according to the present invention will be described in detail with reference to the drawings.
A plasma display panel (PDP) of the present invention includes two substrates on which electrodes are provided, and a large number of minute discharge spaces (hereinafter, referred to as discharge cells) defined by partition walls provided between the substrates. I have. A phosphor layer is provided inside the discharge cell. The PDP generates a plasma discharge in the discharge cell, thereby causing the phosphor to emit visible light. Then, the visible light is transmitted through a substrate disposed on the display side to display various information on a display screen. In the present invention, the phosphor constituting the phosphor layer has an average particle size of 0.01 to 1.0 μm, and the ratio of the phosphor layer in the discharge cells is 10 to 40% by volume.
[0029]
First, a configuration example of a PDP according to the present invention will be described with reference to FIGS.
PDPs can be roughly classified into a DC type that applies a DC voltage and an AC type that applies an AC voltage, depending on the structure and operation mode of the electrodes. Although the PDP of the present invention may be of any type, FIG. 1 shows an AC type PDP 1.
[0030]
One of the two substrates 10 and 20 shown in FIG. 1 is a front plate 10 arranged on the display side, and the other is a rear plate 20 arranged on the back side. The front plate 10 and the rear plate 20 are opposed to each other at a predetermined interval by a partition 30 provided between the substrates 10 and 20.
[0031]
First, the configuration of the front plate 10 will be described.
The front plate 10 can be formed from a material that transmits visible light, such as soda lime glass. As shown in FIG. 1, an electrode 11, a dielectric layer 12, a protective layer, and the like are provided on a surface of the front plate 10 facing the rear plate 20.
[0032]
The electrodes 11 provided on the front plate 10 include a pair of scanning electrodes 11a and sustaining electrodes 11b, and each of the electrodes 11a and 11b is formed in a strip shape. Scan electrode 11a and sustain electrode 11b are provided with a predetermined discharge gap. Plasma discharge for causing the phosphor to emit light is performed by surface discharge between the scan electrode 11a and the sustain electrode 11b.
[0033]
As shown in FIG. 2, the electrodes 11 are provided so as to continuously traverse from the end 10c to the end 10d of the front plate 10, and are regularly arranged at predetermined intervals. Each of the electrodes 11 is connected to a panel drive circuit 15 and can apply a voltage to a desired electrode 11.
[0034]
As shown in FIG. 1, a dielectric layer 12 is provided so as to cover the entire surface of front plate 10 on which these electrodes 11 are arranged. The dielectric layer 12 is made of a dielectric material, and is generally often made of a lead-based low-melting glass. In addition, the dielectric layer 12 may be formed of bismuth-based low-melting glass or a laminate of lead-based low-melting glass and bismuth-based low-melting glass.
[0035]
The surface of the dielectric layer 12 is entirely covered by the protective layer 13. The protective layer 13 is preferably a thin layer made of magnesium oxide (MgO).
[0036]
Next, the configuration of the rear plate 20 will be described.
The back plate 20 is formed to have substantially the same size as the front plate 10, and can be made of soda lime glass or the like, similarly to the front plate 10. A plurality of data electrodes 21, a dielectric layer 22, partition walls 30, and the like are provided on a surface of the back plate 20 facing the front plate 10.
[0037]
The data electrodes 21 are formed in a band shape similarly to the electrodes 11, and are provided at predetermined intervals. The partition 30 is provided on both sides of the data electrode 21. As shown in FIG. 2, the data electrode 21 is divided at a central portion 24 of the back plate 20, and each is connected to the panel drive circuits 25a and 25b. By the panel drive circuit 25, a voltage can be applied to a desired electrode 21.
[0038]
As shown in FIG. 1, the entire surface of the back plate 20 on which the data electrodes 21 are arranged is covered with a dielectric layer 22. Like the dielectric layer 12, the dielectric layer 22 can be made of lead-based low-melting glass, bismuth-based low-melting glass, or a laminate of lead-based low-melting glass and bismuth-based low-melting glass. In addition, these dielectric materials have TiO ₂ It is preferable to mix the particles so that they also function as a visible light reflecting layer. When the dielectric layer 22 also functions as a visible light reflecting layer in this way, even if light is emitted from the phosphor layer 35 to the back plate 20 side, it is reflected to the front plate 10 side and transmitted through the front plate 10. More light to be emitted, and the luminance can be improved.
[0039]
A partition 30 is provided on the upper surface of the dielectric layer 22 so as to protrude from the rear plate 20 to the front plate 10. The partition 30 divides a space between the substrates 10 and 20 into a plurality of predetermined shapes, and forms the discharge cells 31 as described above. The partition 30 is formed from a dielectric material such as a glass material.
[0040]
The discharge cell 31 is a discharge space surrounded by the partition wall 30 and the substrates 10 and 20 as described above, and the side surface 30a of the partition wall 30 facing the inside of the discharge cell 31 and the bottom surface 31a of the discharge cell have red ( The phosphor layers 35 emitting light of any of R), green (G), and blue (B) are regularly provided in the order of R, G, and B. A discharge gas mainly composed of a rare gas is sealed in the discharge cell 31. As the discharge gas, it is particularly preferable to use a mixed gas in which Ne is used as a main discharge gas and Xe which generates ultraviolet rays by discharge is mixed with the main discharge gas. The pressure at which the mixed gas is charged is not particularly limited, but is preferably, for example, about 66.7 mPa.
[0041]
The discharge cell 31 shown in FIG. 1 is of a so-called stripe type, in which partition walls 30 are provided on both sides of the data electrode 21 and formed in parallel grooves by the partition walls 30.
Here, the arrangement of the discharge cells 31 and the electrodes 11 and 21 will be described.
As shown in FIG. 2, the electrodes 11 and the data electrodes 21 are orthogonal to each other in a plan view and are in a matrix. In one discharge cell 31, a number of intersections between the electrode 11 and the data electrode 21 are provided. Discharge can be selectively performed at the intersection of the electrode 11 and the data electrode 21, thereby enabling desired information to be displayed. Hereinafter, the space of a cell obtained by dividing the volume of one cell by the number of intersections of the electrodes in the cell is referred to as a minimum light emitting unit. In the PDP 1, one pixel is formed by three minimum light emission units of R, G, and B adjacent to each other.
[0042]
The cell structure of the PDP according to the present invention is not limited to the above-described stripe type, but is, for example, a lattice type in which partition walls 40 are provided in a grid form to form a substantially rectangular discharge cell 41 as shown in FIG. May be. In this case, at least one intersection of one set of electrodes provided on the front plate side and data electrodes provided on the back plate side is provided inside one discharge cell 41.
[0043]
Further, the cell structure may be a honeycomb type having partition walls 50 provided in a honeycomb shape as shown in FIG. In the case of a honeycomb-type cell structure, a repetitive structure divided by a partition in a substantially hexagonal shape is defined as one discharge cell 51, and is provided inside one discharge cell 51 on the front plate side similarly to the lattice type. At least one intersection of the set of electrodes and the data electrodes provided on the back plate side is provided.
[0044]
Note that the lattice shape and the honeycomb shape refer to shapes in a plan view when the substrate surface of the back plate is horizontally arranged.
[0045]
Next, the phosphor layer will be described.
As described above, the ratio of the phosphor layer in the discharge cell is 10 to 40%, preferably 10 to 30%, and more preferably 10 to 20%.
[0046]
Here, the ratio of the volume of the phosphor layer in the discharge cell can be determined by directly observing the cross section of the discharge cell using, for example, an electron microscope (S-900, manufactured by Hitachi, Ltd.). .
[0047]
Since the ratio of the phosphor layer in the discharge cells is 10 to 40% by volume, the ratio of the discharge space in the discharge cells can be 90 to 60% by volume. It can generate enough ultraviolet light to excite the body. For this reason, it is not necessary to increase the voltage applied when performing the plasma discharge in order to achieve the same level of brightness as in the related art.
[0048]
As described above, the average particle diameter of the phosphor constituting the phosphor layer of the present invention is 0.01 to 1.0 μm, and more preferably 0.01 to 0.5 μm.
[0049]
Here, the average particle diameter of the phosphor is obtained by measuring the average particle diameter of 300 phosphor particles in the phosphor layer using an electron microscope (for example, S-900, manufactured by Hitachi, Ltd.). Value. In addition, when the phosphor particles are so-called normal crystals having a cubic or octahedral shape, the particle size refers to the length of the edge of the phosphor particles. In the case where the phosphor particles are not normal crystals, for example, when the phosphor particles are spherical, rod-shaped, or tabular particles, the diameter refers to a sphere equivalent to the volume of the phosphor particles.
[0050]
Conventionally, the phosphor layer was formed using a phosphor having an average particle size of 2 to 10 μm, whereas the present invention uses a phosphor of an extremely fine particle having an average particle size of 0.01 to 1.0 μm. Make up the body layer. Usually, ultraviolet rays generated in the discharge cells during discharge enter only near the surface of the phosphor, for example, only about 100 nm. For this reason, for example, in the case of a 2 μm phosphor, the volume of the portion contributing to light emission is only about 18% of the volume of the phosphor particles. Therefore, by reducing the average particle size of the phosphor to 0.01 to 1.0 μm as in the present invention, it is possible to increase the ratio of the volume of the phosphor particles that contributes to light emission. Therefore, even if the volume occupied by the phosphor layer in the discharge cell is the same, the use of the fine particle phosphor allows the ultraviolet rays to be received more efficiently than before, thereby improving the luminous efficiency.
[0051]
As described above, the discharge space is secured and the luminous efficiency of the phosphor can be improved. Therefore, even in a high-definition PDP in which the discharge cells are miniaturized, the luminance can be improved as compared with the related art. For this reason, it is possible to reduce the voltage to be applied in order to achieve the same level of brightness as in the related art. Therefore, the concentration of ions generated in the discharge cell during the plasma discharge can be reduced, and the phosphor can be hardly subjected to ion bombardment. As a result, the deterioration of the phosphor can be prevented, and the luminance can be maintained substantially constant even when the PDP is used continuously for a long time.
[0052]
The proportion of the phosphor in the phosphor layer (hereinafter referred to as the filling rate of the phosphor) is 30% to 80%, and more preferably 40% to 80%.
[0053]
Here, the filling rate can be determined according to the following equation.
Phosphor filling factor (%) = ｛(mass of phosphor occupying in discharge cell (g) / d) / (volume of phosphor layer occupying in discharge cell (cm) ³ )｝ × 100
However, in the above formula, the weight of the phosphor occupying the discharge cells is a value obtained by dividing the change in weight before and after the formation of the phosphor layer by the number of discharge cells, and d is the density of the blended phosphor ( g / cm ³ ).
[0054]
Since the filling rate of the phosphor in the phosphor layer is 30 to 80% by volume, the volume ratio of the phosphor layer in the discharge cells can be reduced as compared with the conventional filling rate of less than 30% by volume. The discharge space can be widened. Therefore, luminance can be improved.
[0055]
Further, it is preferable that the particle size distribution of the phosphor is narrow. Specifically, the coefficient of variation of the particle size distribution is preferably 300% or less, more preferably 100% or less, and most preferably 30% or less.
[0056]
Here, the variation coefficient of the particle size distribution (the size of the particle size distribution) is a value defined by the following equation.
Size of particle size distribution (coefficient of variation) (%)
= (Standard deviation of particle size / average value of particle size) x 100 (1)
[0057]
By using a phosphor having a narrow particle size distribution, the phosphor can be more efficiently filled in the phosphor layer. In the phosphor layer having a high filling rate of the phosphor, the amount of the phosphor contained in a unit volume is large, so that the luminous efficiency of the phosphor layer is improved and the luminance can be improved. Therefore, the discharge sustaining voltage can be reduced as compared with the one having a low filling factor, the deterioration of the phosphor can be prevented, and the luminance can be maintained substantially constant even when the PDP is used for a long time.
[0058]
As described above, it is preferable that the fine particles and the phosphor having a narrow particle size distribution be manufactured by a liquid phase synthesis method instead of a conventional solid phase synthesis method.
The liquid phase synthesis method as referred to in the present invention is a method in which a compound containing an element serving as a raw material of a phosphor is reacted in a liquid phase, and specifically, a solution containing an element constituting the phosphor matrix and an activator This is a method of synthesizing a phosphor precursor by mixing solutions containing elements together, and refers to a reaction method in a liquid phase such as a reaction crystallization method, a coprecipitation method, and a sol-gel method. In the present invention, it is possible to manufacture a phosphor by appropriately selecting these methods.
[0059]
In the liquid phase synthesis method, a phosphor raw material is reacted in a liquid phase, so that the reaction is performed between element ions constituting the phosphor. Therefore, a stoichiometrically high-purity phosphor is easily obtained. On the other hand, in the conventional solid-phase synthesis method, since the reaction is a solid-solid reaction, surplus impurities that do not react and secondary salts generated by the reaction often remain, resulting in a stoichiometrically high-purity phosphor. Difficult to obtain. Therefore, by obtaining a stoichiometrically high-purity phosphor by a liquid phase synthesis method, luminous efficiency and yield can be increased.
[0060]
Further, in the conventional solid phase synthesis method, since the phosphor is produced while repeating the solid phase reaction and the pulverizing step, the particle size of the obtained phosphor is relatively large, about 2 to 10 μm. On the other hand, in the liquid phase synthesis method, since the reaction is performed in the liquid phase as described above, the average particle size, particle shape, particle size distribution, emission characteristics, and the like of the phosphor can be more precisely controlled, and the average particle size can be reduced. Particles having a diameter of 0.01 to 1.0 μm can be obtained with a narrow particle size distribution. Therefore, as described above, the ratio of the volume of the phosphor particles that contributes to light emission can be increased, and the luminous efficiency of the phosphor can be increased.
[0061]
Furthermore, in the liquid phase synthesis method, a phosphor having a small particle size and a narrow particle size distribution can be obtained, so that the phosphor can be efficiently filled in the phosphor layer. On the other hand, since the phosphor obtained by the solid phase synthesis method is pulverized in the pulverization step as described above, it is highly likely to be polyhedral, and the particle size distribution is wide. For this reason, even if a phosphor layer is formed, gaps of irregular shapes may be generated in the layer, and the phosphor cannot be efficiently filled. Therefore, even if the same amount (mass) of the phosphor is used, by using the phosphor produced by the liquid phase synthesis method, the ratio of the volume occupied by the phosphor layer in the discharge cell is reduced, and the discharge is reduced. The space can be enlarged and the brightness can be improved.
[0062]
Further, in the solid phase synthesis method, when stress is applied to the phosphor in the pulverization step, there is a possibility that lattice defects may occur in the crystal lattice of the phosphor. Lattice defects in the phosphor absorb the ultraviolet wavelength (147 nm) generated in the cell by the plasma discharge and hinder excitation of the emission center. For this reason, there is a possibility that the brightness may be reduced. However, as described above, in the liquid phase synthesis method, stress is not applied to the phosphor, and there is no possibility that a lattice defect occurs. Therefore, a phosphor with high luminous efficiency can be obtained.
[0063]
Further, if there is a lattice defect in the crystal lattice of the phosphor, the crystallinity tends to be reduced starting from the lattice defect when subjected to ion bombardment, and the phosphor tends to be deteriorated as compared with a phosphor having no lattice defect. That is, even with the same applied voltage, the phosphor manufactured by the solid phase synthesis method is easily deteriorated, and the phosphor manufactured by the liquid phase synthesis method is hardly deteriorated.
[0064]
As described above, by forming the phosphor layer with the phosphor produced by the liquid phase synthesis method, the luminance can be improved and the discharge sustaining voltage can be reduced. Further, since the phosphor itself is not easily deteriorated, the deterioration of the phosphor can be more reliably prevented by lowering the discharge sustaining voltage. Therefore, even when the PDP is used for a long time, the luminance can be maintained substantially constant.
[0065]
The step of producing a phosphor using a liquid phase synthesis method includes a phosphor precursor forming step of mixing phosphor raw materials to form a phosphor precursor, and a drying step of drying the phosphor precursor. are doing. After the drying step, a firing step is performed if necessary. When manufacturing the phosphor according to the present invention, a phosphor in which the surface of the phosphor precursor particles is coated with a metal is basically obtained by firing a dried phosphor precursor. However, depending on the composition of the phosphor, the reaction conditions, and the like, the phosphor may be obtained from the phosphor precursor in the drying step without firing. In that case, the firing step may be omitted. After the firing step, a cooling step of cooling the obtained fired product, a step of performing a surface treatment of the phosphor, or the like may be performed.
Note that the phosphor precursor is an intermediate compound of the phosphor to be produced, and is a compound that becomes a phosphor by a treatment such as drying and baking as described above.
[0066]
First, the precursor forming step will be described. In the precursor formation step, as described above, any liquid phase synthesis method such as a reaction crystallization method, a coprecipitation method, and a sol-gel method may be applied. For example, (Y, Gd) BO commonly used in PDPs ₃ : Eu ³⁺ (Red light emitting phosphor), BaMgAl ₁₀ O ₁₇ : Eu ²⁺ For the (blue light emitting phosphor), it is particularly preferable to form a phosphor precursor by a reaction crystallization method or a coprecipitation method in the presence of a protective colloid described later. By manufacturing in this manner, a phosphor having finer particles and a narrower particle size distribution and higher emission intensity can be obtained. Also, Zn ₂ SiO ₄ : Mn ²⁺ The (green light emitting phosphor) is preferably formed by a mother nucleus method using a silicon compound such as silica as a mother nucleus of a phosphor precursor. By producing in this manner, fine particles having excellent emission intensity and short afterglow time can be obtained. Hereinafter, the reaction crystallization method, the coprecipitation method, and the mother nucleus method will be described.
[0067]
The reaction crystallization method is a method of synthesizing a phosphor precursor by mixing a solution containing an element serving as a raw material of a phosphor by utilizing a crystallization phenomenon. The crystallization phenomenon means that the solid phase precipitates out of the liquid phase when the physical or chemical environment changes due to cooling, evaporation, pH adjustment, concentration, etc., or when the state of the mixed system changes due to a chemical reaction. The phenomenon that comes.
The method for producing a phosphor precursor by the reaction crystallization method in the present invention means a production method by physical or chemical operation that can cause the above-mentioned crystallization phenomenon.
[0068]
As a solvent for applying the reaction crystallization method, any solvent may be used as long as the reaction raw materials are dissolved, but water is preferable from the viewpoint of easy control of the degree of supersaturation. When a plurality of reaction raw materials are used, the order of adding the raw materials may be simultaneous or different, and an appropriate sequence can be appropriately assembled depending on the activity.
[0069]
The co-precipitation method refers to a method of synthesizing a phosphor precursor by mixing a solution or dispersion containing an element serving as a raw material of a phosphor by using a co-precipitation phenomenon, and further adding a precipitant. . The coprecipitation phenomenon refers to a phenomenon in which, when a precipitate is generated from a solution, ions having sufficient solubility in the situation and not supposed to precipitate are accompanied by the precipitation.
[0070]
The mother nucleus method is a method in which a compound containing at least one element constituting a phosphor is used as a mother nucleus, and other elements constituting the phosphor are deposited around the mother nucleus to synthesize a phosphor precursor. Say.
[0071]
As mentioned above, Zn ₂ SiO ₄ : Mn ²⁺ When obtaining a green phosphor composed of a silicate phosphor such as described above, it is preferable to form a precursor by a mother nucleus method. In such a case, a silicon compound such as silica is used as a mother nucleus of the phosphor precursor, and a solution containing a metal element such as Zn or Mn that can constitute a green phosphor by firing is mixed with the mother compound. It is preferable to add a solution containing a precipitant as needed. At this time, as the silica, fumed silica, wet silica, colloidal silica and the like can be preferably used.
[0072]
When synthesizing a precursor by a liquid phase synthesis method, including the above-mentioned reaction crystallization method, coprecipitation method and mother nucleus method, depending on the type of phosphor, the reaction temperature, the addition speed and the addition position, the stirring conditions, It is preferable to adjust various physical property values such as pH. Ultrasonic waves may be applied when dispersing the mother nucleus of the phosphor precursor in the solution or during the reaction. It is also preferable to add a protective colloid or a surfactant for controlling the average particle size. Concentration and / or aging of the liquid as needed after the addition of the raw materials is also a preferred embodiment.
[0073]
The particle size and aggregation state of the phosphor precursor particles are controlled by controlling the amount or rate of the protective colloid to be added, the stirring conditions, and the like, and setting the dispersion state of the mother nucleus of the phosphor precursor in the solution to a preferable state. And the average particle diameter of the fired phosphor can be adjusted to a desired size. In addition, when silica is used as a mother nucleus of a phosphor precursor and a phosphor precursor is formed by a coprecipitation method, colloidal silica whose dispersion state, particle size, and the like are appropriately adjusted to a desired state is used. This also makes it possible to make the average particle size of the fired phosphor to a desired size.
As described above, by controlling the average particle diameter of the phosphor, the number and surface area of the phosphor contained per unit mass of the phosphor can be controlled.
[0074]
As the protective colloid used for controlling the particle size, various polymer compounds can be used regardless of whether they are natural or artificial, and among them, proteins are particularly preferable. At that time, the average molecular weight of the protective colloid is preferably 10,000 or more, more preferably 10,000 or more and 300,000 or less, particularly preferably 10,000 or more and 30,000 or less.
[0075]
Examples of the protein include gelatin, a water-soluble protein, and a water-soluble glycoprotein. Specifically, there are albumin, ovalbumin, casein, soy protein, synthetic protein, protein synthesized by genetic engineering, and the like. Among them, gelatin can be particularly preferably used.
[0076]
Examples of gelatin include lime-treated gelatin and acid-treated gelatin, and these may be used in combination. Further, hydrolysates of these gelatins and enzymatic degradation products of these gelatins may be used.
[0077]
Further, the protective colloid does not need to have a single composition, and various kinds of binders may be mixed. Specifically, for example, a graft polymer of the above gelatin and another polymer can be used.
[0078]
The protective colloid can be added to one or more of the raw material solutions. It may be added to all of the raw material solutions. By forming the phosphor precursor in the presence of the protective colloid, the phosphor precursors can be prevented from aggregating with each other, and the phosphor precursor can be made sufficiently small. This makes it possible to improve various characteristics of the phosphor, such as making the phosphor after firing finer, having a narrower particle size distribution, and improving light emission characteristics. When the reaction is performed in the presence of a protective colloid, it is necessary to sufficiently control the particle size distribution of the phosphor precursor and eliminate impurities such as secondary salts.
[0079]
After synthesizing the phosphor precursor in the phosphor precursor formation step, the phosphor precursor is collected, if necessary, by a method such as filtration, evaporation to dryness, or centrifugation, and then, preferably, washing is performed.
Further, it is preferable to remove impurities such as secondary salts from the phosphor precursor by passing through a desalting step prior to the drying step and the baking step.
As the desalting step, various membrane separation methods, coagulation sedimentation methods, electrodialysis methods, methods using ion-exchange resins, Nudel washing methods, and the like can be applied.
[0080]
By performing the desalting step, the electric conductivity after the desalting of the precursor is preferably in the range of 0.01 to 20 mS / cm, more preferably 0.01 to 10 mS / cm, and particularly preferably 0 to 10 mS / cm. 0.01 to 5 mS / cm.
When the electric conductivity is less than 0.01 mS / cm, the productivity is reduced. On the other hand, if it exceeds 20 mS / cm, since the by-salts and impurities cannot be sufficiently removed, the particles become coarse and the particle size distribution becomes wide, and the light emission intensity deteriorates.
Although any method can be used for measuring the electric conductivity, a commercially available electric conductivity measuring device may be used.
[0081]
In the present invention, a drying step is performed after washing or after a desalting step. The method for drying the phosphor precursor is not particularly limited, and any method such as vacuum drying, flash drying, fluidized-bed drying, and spray drying can be used.
[0082]
Although the drying temperature is not limited, it is preferably a temperature around the temperature at which the solvent used evaporates or more, and specifically, preferably in the range of 50 to 300 ° C. When the drying temperature is high, firing may be performed simultaneously with drying, and the phosphor may be obtained without performing the firing step described below.
[0083]
In the firing step, any method may be used, and the firing temperature and time may be appropriately adjusted. For example, a desired phosphor can be obtained by filling a phosphor precursor into an alumina boat and firing at a predetermined temperature in a predetermined gas atmosphere. As a gas atmosphere, conditions such as an inert gas, a reducing atmosphere, an oxidizing atmosphere, or a sulfide atmosphere may be appropriately selected according to a phosphor to be manufactured.
[0084]
As an example of preferable firing conditions, firing is performed at 600 ° C. to 1800 ° C. for an appropriate time in various atmospheres. In addition, in order to remove organic substances, it is also effective to perform baking at about 800 ° C. in the air, and then perform baking under different baking conditions.
[0085]
As the firing device (firing container), any device currently known can be used. For example, a box furnace, a crucible furnace, a cylindrical tube type, a boat type, a rotary kiln and the like are preferably used. As the atmosphere, an oxidizing, reducing, or inert gas can be used in accordance with the composition of the precursor.
[0086]
During firing, a sintering inhibitor may be added as necessary. When a sintering inhibitor is added, it may be added as a slurry at the time of forming the phosphor precursor, or a powdered material may be mixed with the dried precursor and fired.
The sintering inhibitor is not particularly limited, and is appropriately selected depending on the type of the phosphor and the firing conditions. For example, when firing at 800 ° C. or less depending on the firing temperature range of the phosphor, TiO 2 is used. ₂ Metal oxide such as SiO. ₂ However, firing at 1700 ° C or lower requires Al ₂ O ₃ Are each preferably used.
Further, after the firing, a reduction treatment or an oxidation treatment may be performed as necessary.
[0087]
After the firing step, various steps such as a cooling step, a surface treatment step, and a dispersion step may be performed, or classification may be performed.
[0088]
In the cooling step, a process of cooling the fired product obtained in the firing step is performed. At this time, the fired product can be cooled while being filled in the firing device.
Although the cooling treatment is not particularly limited, it can be appropriately selected from known cooling methods. For example, a method of lowering the temperature by leaving it alone or a method of forcibly lowering the temperature while controlling the temperature using a cooler can be used. Any one may be used.
[0089]
The phosphor produced by the present invention can be subjected to surface treatment such as adsorption and coating for various purposes. The point at which the surface treatment is performed depends on the purpose, and the effect becomes more remarkable when appropriately selected. For example, when preparing a phosphor paste as described below, it is preferable to perform a surface treatment to improve the dispersibility of the phosphor.
[0090]
Next, a method of forming a phosphor layer using the phosphor obtained above will be described.
In forming the phosphor layer, the phosphor is dispersed in a mixture of a binder, a solvent, a dispersant, and the like, and a phosphor paste adjusted to an appropriate viscosity is applied or filled in the discharge cell, and then fired, and the side wall of the partition is fired. And forming a phosphor layer on the bottom surface. The content of the phosphor in the phosphor paste is preferably in the range of 30% by mass to 60% by mass.
[0091]
By changing the ratio between the phosphor and the non-volatile component in the phosphor paste, the filling rate of the phosphor in the phosphor layer can be controlled. Here, the non-volatile components are other components obtained by removing the phosphor and the solvent from the phosphor paste.
[0092]
In order to improve the dispersibility of the phosphor in the paste, it is preferable to perform a surface treatment such as attaching or coating an oxide or a fluoride on the surface of the phosphor. Such oxides include, for example, magnesium oxide (MgO), aluminum oxide (Al ₂ O ₃ ), Silicon oxide (SiO ₂ ), Indium oxide (InO) ₃ ), Zinc oxide (ZnO), yttrium oxide (Y ₂ O ₃ ). Among them, SiO ₂ Is known as a negatively charged oxide, while ZnO, Al ₂ O ₃ , Y ₂ O ₃ Are known as positively charged oxides, and it is particularly effective to attach or coat these oxides.
[0093]
Hereinafter, a binder, a solvent, a dispersant, and the like mixed with the phosphor will be described.
Binders suitable for dispersing the phosphor well include ethyl cellulose and polyethylene oxide (polymer of ethylene oxide), and particularly, an ethoxy group (-OC ₂ H ₅ ) Is preferably used. Further, a photosensitive resin can be used as the binder. The content of the binder is preferably in the range of 0.15% by mass to 10% by mass. In order to adjust the shape of the phosphor paste applied between the partition walls, the content of the binder is preferably set to a relatively large value as long as the paste viscosity does not become too high.
[0094]
As the solvent, a mixture of an organic solvent having a hydroxyl group (OH group) is preferably used. Specific examples of the organic solvent include terpineol (C ₁₀ H ₁₈ O), butyl carbitol acetate, pentanediol (2,2,4-trimethylpentanediol monoisobutyrate), dipentene (Dipentene, also known as Limonen), butyl carbitol and the like. A mixed solvent obtained by mixing these organic solvents is excellent in solubility for dissolving the above-mentioned binder, and good in dispersibility of the phosphor paste. As such a mixed solvent, for example, a 1: 1 mixed solution of terpioneol and pentadiol is exemplified.
[0095]
In order to improve the dispersion stability of the phosphor in the phosphor paste, it is preferable to add a surfactant as a dispersant. The content of the surfactant in the phosphor paste is preferably 0.05% by mass to 0.3% by mass from the viewpoint of effectively improving the dispersion stability or effectively eliminating the electricity described below.
[0096]
As specific examples of the surfactant, (a) an anionic surfactant, (b) a cationic surfactant, and (c) a nonionic surfactant can be used. There is something.
(A) Examples of the anionic surfactant include fatty acid salts, alkyl sulfates, ester salts, alkyl benzene sulfonates, alkyl sulfosuccinates, and naphthalene sulfonate polycarboxylic acid polymers.
(B) Examples of the cationic surfactant include an alkylamine salt, a quaternary ammonium salt, an alkyl betaine, and an amine oxide.
(C) Examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene derivative, sorbitan fatty acid ester, glycerin fatty acid ester, and polyoxyethylene alkylamine.
[0097]
Further, it is preferable to add a charge removing substance to the phosphor paste. The above-mentioned surfactants also generally have a charge eliminating action for preventing charging of the phosphor paste, and many of them correspond to charge eliminating substances. However, since the static elimination action differs depending on the type of the phosphor, the binder, and the solvent, it is preferable to conduct a test on various types of surfactants and select a surfactant having a good result.
[0098]
Examples of the charge removing substance include fine particles made of a conductive material in addition to the surfactant. As the conductive fine particles, fine carbon powders such as carbon black, fine graphite powders, fine powders of metals such as Al, Fe, Mg, Si, Cu, Sn and Ag, and fine powders of these metal oxides Is mentioned. The amount of such conductive fine particles to be added is preferably in the range of 0.05 to 1.0% by mass based on the phosphor paste.
[0099]
By adding a charge removing substance to the phosphor paste, the phosphor paste is charged, for example, to the swelling of the phosphor layer at the break of the data electrode in the center of the panel, or to the amount or groove of the phosphor paste applied in the cell. It is possible to prevent a phosphor layer from being formed poorly, such as a slight variation in the adhesion state of the phosphor, and to form a uniform phosphor layer for each cell.
[0100]
When a surfactant or carbon fine powder is used as the charge removing substance as described above, the charge removing substance is also evaporated or burned off in the phosphor baking step of removing the solvent and the binder contained in the phosphor paste. Therefore, the charge removing substance does not remain in the phosphor layer after firing. Therefore, there is no possibility that driving (light emitting operation) of the PDP will be affected by the residual charge removing substance remaining in the phosphor layer.
[0101]
Viscosity of phosphor paste mixed with above (shear rate 100 sec at 25 ° C.) ^-1 Is preferably adjusted to 2 Pa · s or less, and more preferably 0.01 Pa · s to 0.5 Pa · s.
[0102]
When dispersing the phosphor in the various mixtures, for example, a medium medium such as a high-speed stirring impeller type disperser, a colloid mill, a roller mill, a ball mill, a vibration ball mill, an attritor mill, a planetary ball mill, and a sand mill are moved in the apparatus. One that can be atomized by both collision and shearing force, or a dry disperser such as a cutter mill, a hammer mill, and a jet mill, an ultrasonic disperser, a high-pressure homogenizer, and the like can be used.
[0103]
In addition, at the time of preparing the phosphor paste, from the viewpoint of preventing deterioration of various properties such as the luminance of the phosphor, the dispersion treatment is performed while controlling the temperature of the dispersion from the start to the end so as not to exceed 70 ° C. The dispersion treatment is more preferably performed while controlling the temperature not to exceed 50 ° C.
[0104]
When applying or filling the phosphor paste adjusted as described above to the discharge cells, various methods such as a screen printing method, a photoresist film method, and an inkjet method can be used.
[0105]
In particular, the ink-jet method is preferable because the phosphor paste can be easily and accurately and uniformly applied at low cost between the partition walls with high accuracy even when the pitch of the partition walls is narrow and the discharge cells are finely formed. In the present invention, fine phosphors manufactured by a liquid phase synthesis method of 1.0 μm or less are used, so even if the inkjet method is applied, nozzle clogging, ejection failure, and phosphor precipitation are suppressed. Thus, a thin phosphor layer can be accurately and uniformly formed.
[0106]
After the phosphor paste is applied or filled, organic components and the like are removed by drying or baking to form a phosphor layer attached to the side wall of the partition or the bottom of the discharge cell. At this time, when the partition wall side and the discharge cell bottom surface that can be covered with the phosphor layer are the phosphor layer coverable surface, the amount of the phosphor adhering to the partition wall side and the discharge cell bottom surface (the amount of the phosphor) is determined by the phosphor layer. 20 g / m2 per unit area of coatable surface ² Above, 100 g / m ² The following is preferred.
[0107]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples 1 to 3, but the present invention is not limited thereto.
[0108]
[Example 1]
In Example 1, a PDP was manufactured in which the ratio of the phosphor layer in the discharge cells was 30% using phosphors having different average particle diameters, and the particle diameter of the phosphor and the luminance degradation were evaluated.
First, the manufacture of the phosphor will be described.
[0109]
1. Blue light emitting phosphor (BaMgAl ₁₀ O ₁₇ : Eu ²⁺ ) Manufacturing
(1) Production of blue light-emitting phosphor B-1 (average particle size 0.8 μm)
First, 9 g of gelatin (average molecular weight of about 10,000) was dissolved in 300 g of pure water to prepare solution A. At the same time, 1.76 g of barium nitrate, 1.92 g of magnesium nitrate hexahydrate, 28.13 g of aluminum nitrate nonahydrate and 0.33 g of europium nitrate hexahydrate are dissolved in 136.48 g of pure water, and the solution B is dissolved. It was adjusted. Further, 23.33 g of aqueous ammonia (28%) was mixed with 124.07 g of pure water to prepare a liquid C.
[0110]
Next, while stirring the solution A, the solution B and the solution C were simultaneously added to the surface of the solution A by a double jet at an addition rate of 5 cc / min using a roller pump.
After the completion of the addition of the liquids B and C, the solid-liquid separation was performed by suction filtration, and the solids were sufficiently washed with pure water. Next, drying was performed at 100 ° C. for 12 hours to obtain a dried precursor.
[0111]
The obtained dried precursor was baked at 600 ° C. for 1 hour in the air to remove residual organic substances such as gelatin from the precursor. Thereafter, the mixture was calcined at 1600 ° C. for 3 hours in a reducing atmosphere of 95% nitrogen and 5% hydrogen to obtain a blue light emitting phosphor B-1 having an average particle diameter of 0.8 μm.
[0112]
(2) Production of blue light-emitting phosphor B-2 (average particle size: 0.4 μm)
First, a solution A was prepared by dissolving 15 g of gelatin (average molecular weight: about 10,000) in 300 g of pure water. At the same time, 3.55 g of barium nitrate, 3.85 g of magnesium nitrate hexahydrate, 56.27 g of aluminum nitrate nonahydrate and 0.67 g of europium nitrate hexahydrate were dissolved in 122.97 g of pure water, and the solution B was dissolved. It was adjusted. Further, 46.67 g of aqueous ammonia (28%) was mixed with 98.15 g of pure water to prepare a liquid C.
[0113]
Next, while stirring the solution A, the solution B and the solution C were simultaneously added to the surface of the solution A by a double jet at an addition rate of 10 cc / min using a roller pump.
After the addition of the liquids B and C, solid-liquid separation, washing, drying, baking, etc. were performed in the same manner as in the above (1) to produce a blue light emitting phosphor B-2 having an average particle diameter of 0.4 μm. .
[0114]
2. Green light-emitting phosphor (Zn ₂ SiO ₄ : Mn ²⁺ )Manufacturing of
(1) Production of green light-emitting phosphor G-1 (average particle size 0.7 μm)
First, silicon dioxide (Aerosil 130 manufactured by Nippon Aerosil Co., Ltd., BET specific surface area 130 m ² / G) 4.51 g was mixed with 297.95 g of pure water to prepare solution A. At the same time, a solution B was prepared by dissolving 42.39 g of zinc nitrate hexahydrate and 2.15 g of manganese nitrate hexahydrate in 126.84 g of pure water. Then, 21.90 g of aqueous ammonia (28%) was mixed with 125.67 g of pure water to prepare a liquid C.
[0115]
Next, while stirring the solution A, the solution B and the solution C were simultaneously added to the surface of the solution A by a double jet at an addition rate of 10 cc / min using a roller pump. After the completion of the addition of the liquids B and C, the solid-liquid separation was performed by suction filtration, and the solids were sufficiently washed with pure water. Next, drying was performed at 100 ° C. for 12 hours to obtain a dried precursor.
The obtained precursor was fired at 1200 ° C. for 3 hours in an atmosphere of 100% nitrogen to obtain a green light-emitting phosphor G-1 having an average particle diameter of 0.7 μm.
[0116]
(2) Production of green light-emitting phosphor G-2 (average particle size: 0.4 μm)
In the above (1), the average particle diameter is the same as in the above (1) except that a mixture of 15.02 g of colloidal silica (KLEBOSOL30R25, 30 wt%, manufactured by Clariant) in 287.38 g of pure water is used as the liquid A. Produced a green light-emitting phosphor G-2 having a thickness of 0.4 μm.
[0117]
3. Red light-emitting phosphor ((Y, Gd) BO ₃ : Eu ³⁺ ) Production of R-1
(1) Red light-emitting phosphor (average particle size 0.7 μm)
First, a solution A was prepared by dissolving 9 g of gelatin (average molecular weight 10,000) in 300 g of pure water. At the same time, 13.8 g of yttrium nitrate hexahydrate, 9.20 g of gadolinium nitrate and 1.30 g of europium nitrate hexahydrate were dissolved in pure water to prepare 150 ml of solution B. Further, boric acid (H ₃ BO ₃ 3.) 3.60 g was dissolved in pure water to prepare 150 ml of solution C.
[0118]
Next, while stirring the solution A, the solution B and the solution C were simultaneously added to the surface of the solution A by a double jet at an addition rate of 10 cc / min using a roller pump. After the completion of the addition of the liquids B and C, the solid-liquid separation was performed by suction filtration, and the solids were sufficiently washed with pure water. Next, drying was performed at 100 ° C. for 12 hours to obtain a dried precursor.
The obtained precursor was fired at 1400 ° C. for 3 hours in the air to obtain a red light emitting phosphor R-1 having an average particle diameter of 0.4 μm.
[0119]
(2) Production of red phosphor R-2 (average particle size 0.3 μm)
First, a solution A was prepared by dissolving 15 g of gelatin (average molecular weight: about 10,000) in 300 g of pure water. 26.76 g of yttrium nitrate hexahydrate, 18.40 g of gadolinium nitrate and 2.60 g of europium nitrate hexahydrate were dissolved in pure water to prepare 150 ml of solution B. Further, 150 ml of solution C was prepared by dissolving 7.20 g of boric acid in pure water.
[0120]
Next, while stirring the solution A, the solution B and the solution C were simultaneously added to the surface of the solution A by a double jet at an addition rate of 30 cc / min using a roller pump.
After the addition of the liquids B and C, solid-liquid separation, washing, drying, baking and the like were performed in the same manner as in the above (1) to produce a red light emitting phosphor R-2 having an average particle diameter of 0.3 μm.
[0121]
4. Adjustment of phosphor paste
Phosphor pastes were prepared using the light-emitting phosphors B-1, B-2, G-1, G-2, R-1, and R-2 produced in the above 1 respectively.
At the time of the adjustment, the solid concentration of each of the phosphors B-1, B-2, G-1, G-2, R-1, and R-2 was set to 40% by mass, and ethyl cellulose and polio were used. Each was mixed with a 1: 1 mixture of xylene alkyl ether, terpineol and pentadiol. Each of the obtained mixtures was used as a phosphor paste BP-1, BP-2, GP-1, GP-2, RP-1, or RP-2 to be applied to a PDP cell described later.
[0122]
5. Manufacture of PDP
(1) Production of PDP1-1
Using the blue light-emitting phosphor paste BP-1, green light-emitting phosphor paste GP-1, and red light-emitting phosphor paste RP-1 prepared above, a 42-inch PDP shown in FIG. 1 was manufactured as follows.
[0123]
First, scan electrodes 11a and sustain electrodes 11b were formed on a glass substrate serving as front plate 10 by an inkjet method using a nozzle having a diameter of 50 μm. At this time, while keeping the distance between the nozzle tip and the front plate at 1 mm, the nozzle tip scans a predetermined position on the front plate 10 while discharging the electrode material ink to form a scanning electrode 11a having an electrode width of 60 μm. The sustain electrodes 11b were respectively formed.
Next, a low-melting glass is printed on the front plate 10 via the electrodes 11 and is fired at 500 to 600 ° C. to form a dielectric layer 12. The protective film 13 was formed by vapor deposition.
[0124]
On the other hand, a data electrode 21 was formed on a glass substrate serving as a back plate 20. Similarly to the above, a data electrode 21 having a width of 60 μm was formed using a nozzle having a diameter of 50 μm while maintaining a distance of 1 mm from the back plate 20 and scanning a predetermined position. Next, stripe-shaped barrier ribs 30 were formed using low-melting glass so as to be located on both sides of the data electrode. The interval (pitch) between the partitions 30 was 0.36 mm, and the height of the partitions 30 was 0.15 mm.
[0125]
Furthermore, the phosphor pastes BP-1, GP-1, RP-, RP-, which emit light of each color adjusted in the above 2, are provided on the bottom surface 31a facing the inside of the cell 31 partitioned by the partition wall 30 and the side surface 30a of the partition wall 30. 1 was applied to adjacent cells one by one in a regular order. At this time, the amount of the phosphor paste was adjusted and applied so that the ratio of the volume of the fired phosphor layer to the volume of the cell 31 was 30%.
[0126]
Then, the front plate 10 on which the electrodes 11, 21 and the like are arranged and the rear plate 20 are aligned so that their respective electrode arrangement surfaces face each other, and the gap is kept about 1 mm by the partition wall 30. The periphery is sealed with seal glass. A gas mixture of xenon (Xe), which generates ultraviolet rays by discharge, and neon (Ne), a main discharge gas, was sealed between the substrates 10 and 20, and hermetically sealed. The mixing volume ratio of xenon and neon was 1: 9, and the filling pressure was 66.7 mPa. Thereafter, aging was performed to obtain PDP1-1.
[0127]
(2) Production of PDP1-2
In the above 5 (1), except that the blue light-emitting phosphor paste BP-2, the green light-emitting phosphor paste GP-2, and the red light-emitting phosphor paste RP-2 were used, PDP1-2 was used in the same manner as PDP1-1. Manufactured.
[0128]
[Comparative Example 1]
For comparison with the above PDP1-1 and PDP1-2, a phosphor was produced by a solid phase synthesis method, and a PDP was produced using this phosphor.
First, a method of manufacturing the phosphor of each color will be described.
[0129]
1. Manufacture of phosphor
(1) Blue light-emitting phosphor (BaMgAl ₁₀ O ₁₇ : Eu ²⁺ ) Production of B-3
As a raw material, barium carbonate (BaCO ₃ ), Magnesium carbonate (MgCO ₃ ), Aluminum oxide (α-Al ₂ O ₃ ) Are mixed at a molar ratio of 1: 1: 5 to prepare a mixture. Next, a predetermined amount of europium oxide (Eu) was added to the mixture. ₂ O ₃ ) Is added. Then, an appropriate amount of flux (AlF ₂ , BaCl ₂ ), And calcined at 1600 ° C. for 3 hours in a reducing atmosphere of 95% nitrogen and 5% hydrogen to obtain a phosphor. The obtained phosphor was classified, and one having an average particle size of 1.8 μm was designated as a blue light emitting phosphor G-3.
[0130]
(2) Green emitting phosphor (ZnSiO ₄ : Mn) Production of G-3
As raw materials, zinc oxide (ZnO), silicon dioxide (SiO ₂ ) Are mixed at a molar ratio of 2: 1 to prepare a mixture. Next, a predetermined amount of manganese oxide (Mn) was added to this mixture. ₂ O ₃ ) Was added and mixed in a ball mill, and then fired at 1,200 ° C. for 3 hours in an atmosphere of 10% nitrogen to obtain a phosphor. The obtained phosphor was classified, and the one having an average particle size of 1.8 μm was defined as a green light-emitting phosphor G-3.
[0131]
(3) Red light-emitting phosphor ((Y, Gd) BO ₃ : Eu ³⁺ ) Production of R-3
Yttrium oxide (Y ₂ O ₃ ) And gadolinium oxide (Gd ₂ O ₃ ) And boric acid (H ₃ BO ₃ ) Was blended so that the atomic ratio of Y, Gd, and B was 0.60: 0.40: 1.0 to prepare a mixture. Next, a predetermined amount of europium oxide (Eu) was added to the mixture. ₂ O ₃ ) Is added. The mixture was mixed with an appropriate amount of flux in a ball mill, and fired at 1400 ° C. for 3 hours in an air atmosphere to obtain a phosphor. The obtained phosphor was classified, and one having an average particle size of 1.8 μm was designated as a red light-emitting phosphor R-3.
[0132]
2. Adjustment of phosphor paste
Except that the phosphors B-3, G-3, and R-3 obtained above were used, the respective color light-emitting phosphor pastes BP-3, GP-3, and RP-3 were adjusted in the same manner as in Example 1-2. did.
[0133]
3. Manufacture of PDP
In 5 (1) of Example 1, except that the blue light emitting phosphor paste BP-3, the green light emitting phosphor paste GP-3, and the red light emitting phosphor paste RP-3 were used, the same as 5 in Example 1 was used. PDP was manufactured. The amount of the phosphor paste used was adjusted such that the ratio of the volume occupied by the phosphor layer after firing to the volume of the discharge cells was 30%.
[0134]
[Evaluation 1]
Regarding the PDP1-1 and PDP1-2 manufactured as described above and the PDP manufactured in Comparative Example 1, first, the initial panel luminance was 1,000 cd / m. ² The discharge sustaining voltage (frequency 30 Hz) was continuously applied for 24 hours. Thereafter, the panel luminance after applying the voltage for 24 hours was measured, and the luminance deterioration rate was obtained according to the following equation. Table 1 shows the results.
Brightness deterioration rate = (Brightness after applying voltage for 24 hours-1,000 cd / m ² ) / 1,000 cd / m ² × 100
[Table 1]

[0135]
As is clear from Table 1, the luminance degradation rate of Comparative Example 1 is -9.7%, whereas the luminance degradation rate of PDP1-1 is -1.5%, and the luminance degradation rate of PDP1-2 is As compared with Comparative Example 1, the luminance degradation rate of the PDP of the present invention was lower than that of Comparative Example 1, and it was possible to maintain almost the same luminance as the initial panel luminance even when a voltage was continuously applied for 24 hours. is made of.
[0136]
This is considered for the following reason.
First, PDP1-1 uses a phosphor having an average particle size of 0.8 μm or 0.7 μm, and PDP1-2 uses a phosphor having an average particle size of 0.4 μm or 0.3 μm. On the other hand, in Comparative Example 1, a phosphor having an average particle size of 1.8 μm is used. Since the ultraviolet rays generated in the discharge cells enter only near the surface layer of the phosphor, the ratio of the volume of the phosphor particles that contributes to light emission to the volume of the phosphor particles can be increased by atomizing the phosphor. Thereby, the brightness of the PDP when the same voltage is applied can be improved. For this reason, 1,000 cd / m ² The voltage required to achieve the initial panel luminance of PDP1-1 and PDP1-2 can be lower than that of the comparative example. Thereby, PDP1-1 and PDP1-2 can reduce the ion concentration generated in the discharge cell as compared with Comparative Example 1, protect the phosphor from ion bombardment, and prevent the phosphor from deteriorating. be able to.
[0137]
Further, the phosphors used in PDP1-1 and PDP1-2 are those manufactured by a liquid phase synthesis method. On the other hand, the phosphor used in Comparative Example 1 was manufactured by a solid phase synthesis method. In the liquid phase synthesis method, as described above, by changing the addition amount of the protective colloid, the addition speed of the reaction solution, and the like, it is possible to produce a fine particle diameter, and to mechanically pulverize the phosphor. Does not include steps. On the other hand, in the solid phase synthesis method, there is a step of mixing with a ball mill during the synthesis of the phosphor. At this time, the phosphor is crushed and stress is applied, so that there is a high possibility that a lattice defect occurs in the crystal lattice. For this reason, the phosphor obtained by the solid phase synthesis method is liable to be degraded when subjected to ion bombardment during plasma discharge. On the other hand, in the liquid phase synthesis method, since such stress is not applied at all, the possibility that lattice defects or the like are generated in the crystal lattice is low.
[0138]
As described above, PDP1-1 and PDP1-2 can lower the discharge sustaining voltage compared to Comparative Example 1, and PDP1-1 and PDP1-2 are phosphors that are less likely to deteriorate than Comparative Example 1. As shown in Table 1, the luminance degradation rate of PDP1-1 and PDP1-2 is considered to be lower than that of Comparative Example 1.
[0139]
[Example 2]
Next, a second embodiment will be described. In the second embodiment, a PDP having a different volume ratio of the phosphor layer in the discharge cells is manufactured using the phosphors B-1, G-1, and R-1 manufactured in the first embodiment. Was evaluated.
First, the production of PDP 2-1 will be described.
[0140]
1. Production of PDP2-1
In 5 (1) of Example 1, the amount of the blue phosphor paste BP-1, the green phosphor paste GP-1, and the red phosphor paste RP-1 was determined based on the volume of the discharge cell 31 and the fired phosphor. PDP2-1 was manufactured in the same manner as in 5 (1) of Example 1, except that the ratio of the volume occupied by the layer 35 was adjusted to 15%.
[0141]
2. Production of PDP2-2
In 5 (1) of Example 1, the amounts of the blue phosphor paste BP-1, the green phosphor paste GP-1, and the red phosphor paste RP-1 were determined by comparing the volumes of the discharge cells 31 with the baked fluorescence. PDP2-2 was manufactured in the same manner as 5 (1) of Example 1, except that the volume ratio occupied by the body layer 35 was adjusted to 35%.
[0142]
[Comparative Example 2]
(1) Adjustment of phosphor paste
In 5 (1) of Example 1, the amount of the blue phosphor paste BP-1, the green phosphor paste GP-1, and the red phosphor paste RP-1 was determined based on the volume of the discharge cell 31 and the fired phosphor. A PDP was manufactured in the same manner as in 5 (1) of Example 1 except that the volume ratio occupied by the layer 35 was adjusted to 60%, and Comparative Example 2 was obtained.
[0143]
[Evaluation 2]
Regarding the PDPs 2-1 and 2-2 manufactured in the above and the PDP manufactured in the comparative example 2, the initial panel luminance was 1,000 cd / m. ² The discharge sustaining voltage (frequency 30 Hz) was continuously applied for 24 hours to evaluate the luminance deterioration rate. Table 2 shows the results.
[Table 2]

[0144]
As is clear from Table 2, the luminance degradation rate of Comparative Example 2 is -7.8%, whereas the luminance degradation rate of PDP2-1 is -1.8%, and the luminance degradation rate of PDP2-2 is As compared with Comparative Example 1, the luminance degradation rate of the PDP of the present invention is lower than that of Comparative Example 1, and the luminance is almost the same as the initial panel luminance even when the sustaining voltage is continuously applied for 24 hours. I can do it.
[0145]
This is considered for the following reason.
First, in Comparative Example 2, the ratio of the phosphor layer in the discharge cells is very high at 60%, and the discharge space is 40%. On the other hand, in the PDP2-1, the ratio of the phosphor layer in the discharge cells is 15%, and the discharge space is as high as 85%. In PDP1-2, the ratio of the phosphor layer in the discharge cells is 35%, and the discharge space is 65%. In Comparative Example 2, although the amount of the phosphor used is larger than that of PDP2-1 and PDP2-2, the discharge space is narrower, so that sufficient ultraviolet light to excite the phosphor may be generated. No, the brightness decreases. To compensate for this decrease in luminance, a high voltage must be applied.
[0146]
On the other hand, in PDP2-1 and PDP2-2, although the amount of the phosphor applied is smaller than that in Comparative Example 2, the discharge space is sufficiently ensured, so that the luminance is high. The voltage can also be made lower than in Comparative Example 2. Therefore, as compared with Comparative Example 2, in PDP2-1 and PDP2-2, the ion concentration in the discharge cells can be reduced, and the phosphor can be less susceptible to ion bombardment. For this reason, as shown in Table 2, even if a voltage is continuously applied for 24 hours, luminance degradation can be suppressed to a low level.
[0147]
[Example 3]
Next, a third embodiment will be described. In Example 3, PDPs having different filling ratios of the phosphors were manufactured using the phosphors B-1, G-1, and R-1 manufactured in Example 1, and the luminance degradation was evaluated.
First, the manufacture of PDP 3-1 will be described.
[0148]
1. Production of PDP3-1
(1) Adjustment of phosphor paste
In Example 1-4, each color light-emitting fluorescent material was prepared in the same manner as in Example 1-4, except that the solid content concentration of each color light-emitting phosphor B-1, G-1, and R-1 was 25% by mass. Body paste BP-11, GP-11 and RP-11 were prepared.
[0149]
(2) Production of PDP
In 5 (1) of Example 1, the amounts of the blue phosphor paste BP-11, the green phosphor paste GP-11, and the red phosphor paste RP-11 adjusted above were fired with respect to the volume of the discharge cell 31. PDP3-1 was manufactured in the same manner as 5 (1) of Example 1, except that the volume ratio occupied by the phosphor layer 35 later was adjusted to 15%. At this time, the filling rate of the phosphor was 34.5%.
[0150]
2. Production of PDP3-2
(1) Adjustment of phosphor paste
In Example 4-4, each color emission fluorescent material was prepared in the same manner as in Example 1-4, except that the solid concentration of each color light-emitting phosphor B-1, G-1, and R-1 was 50% by mass. Body paste BP-12, GP-12 and RP-12 were prepared.
[0151]
(2) Production of PDP
In 5 (1) of Example 1, the amounts of the blue phosphor paste BP-12, green phosphor paste GP-12, and red phosphor paste RP-12 adjusted as described above were fired with respect to the volume of the discharge cell 31. PDP3-2 was manufactured in the same manner as 5 (1) of Example 1, except that the volume ratio occupied by the phosphor layer 35 later was adjusted to 15%. At this time, the filling factor of the phosphor was 69.0%.
[0152]
[Comparative Example 3]
(1) Adjustment of phosphor paste
In Example 1, 4 each color was changed in the same manner as in Example 1, 4 except that the solid content concentration of each color light emitting phosphor B-1, G-1, and R-1 was 7.5 mass%. The light emitting phosphor pastes BP-13, GP-13, and RP-13 were prepared.
[0153]
(2) Production of PDP
In 5 (1) of Example 1, the amounts of the blue phosphor paste BP-13, green phosphor paste GP-13, and red phosphor paste RP-13 adjusted as described above were fired with respect to the volume of the discharge cell 31. A PDP was manufactured in the same manner as 5 (1) of Example 1 except that the volume ratio occupied by the phosphor layer 35 was adjusted to 50%, and Comparative Example 3 was obtained. At this time, the filling factor of the phosphor was 10.4%.
[0154]
[Evaluation 3]
As for the PDPs 3-1 and 3-2 manufactured in the above and the PDP manufactured in the comparative example 3, the discharge sustaining voltage (frequency 30 Hz) was set to 24 so that the initial panel luminance became 1,000 cd / m2, as in the evaluation 1. The voltage was continuously applied for a period of time to evaluate the luminance deterioration rate. Table 3 shows the results.
[Table 3]

[0155]
As is clear from Table 3, the luminance degradation rate of Comparative Example 3 is -8.4%, whereas the PDP3-1 has a low value of -2.3% and the PDP3-2 has a low value of -1.0%. This indicates that even if a voltage is continuously applied for 24 hours, the luminance is almost the same as the initial panel luminance.
This is considered for the following reason.
[0156]
First, the ratio of the phosphor layer in the discharge cell of Comparative Example 3 is as high as 50%. Therefore, in Comparative Example 3, the discharge space is 50% of the discharge cells. On the other hand, it is 15% in PDP3-1 and PDP3-2, and 85% of the discharge space is secured.
Furthermore, in Comparative Example 3, the filling rate of the phosphor is lower than that of PDP3-1 and PDP3-2, although the ratio of the phosphor layer is high. The phosphor filling rate of Comparative Example 3 is 10.4%, and the ratio of the volume occupied by the phosphor particles in the discharge cell is 5.2%. On the other hand, the phosphor filling rate of PDP 3-1 is 34.5%, and the ratio of the volume occupied by the phosphor particles in the discharge cells is 5.75%. The phosphor filling rate of PDP3-2 is 69.0%, and the ratio of the volume occupied by the phosphor particles in the discharge cells is 10.35%.
[0157]
As described above, in Comparative Example 3, the ratio of the volume occupied by the phosphor particles in the discharge cell is small, and the discharge space is small, so that 1,000 cd / m 2 is obtained. ² The applied voltage required to achieve the initial panel luminance of the above also increases. On the other hand, in PDP3-1, the ratio of the volume occupied by the phosphor particles in the discharge cells is 5.12%, which is almost the same as that of Comparative Example 3, but the ratio of the discharge space is as high as 85%. For this reason, the discharge sustaining voltage can be lower than in Comparative Example 3. In PDP3-2, since the filling rate of the phosphor is high, the discharge space is 85%, and the ratio of the volume occupied by the phosphor particles in the discharge cells is about the same as that of Comparative Example 3 and PDP3-1. Doubled. Therefore, the discharge sustaining voltage can be further reduced.
[0158]
For this reason, the ion concentration in the discharge cells can be made lower in PDP3-1 and PDP3-2 than in Comparative Example 3, protecting the phosphor from ion bombardment and preventing the phosphor from deteriorating. . Therefore, as shown in Table 3, the luminance degradation rate is low, and the luminance can be maintained substantially constant even when used continuously for a long time.
[0159]
【The invention's effect】
According to the present invention, the phosphor layer is formed using an extremely fine phosphor having an average particle size of 0.01 to 1.0 μm, and the ratio of the volume occupied by the phosphor layer in the discharge cell is 10 to 10 μm. By setting it to 40%, the discharge space can be enlarged, and the luminous efficiency can be improved by efficiently receiving ultraviolet rays. As a result, the brightness can be improved even for a PDP with a high definition. For this reason, in order to achieve the same level of brightness as in the related art, it is possible to lower the applied voltage during the sustaining of the discharge, and to protect the phosphor from deterioration due to ion bombardment. Therefore, even if the PDP is used for a long time, the luminance can be maintained substantially constant.
The same effect can be obtained by setting the ratio of the volume occupied by the phosphor in the phosphor layer to 30 to 80%.
Furthermore, by manufacturing the phosphor by a liquid phase synthesis method, it is possible to prevent lattice defects in the crystal and to make the phosphor less likely to deteriorate.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an example of a plasma display panel according to the present invention.
FIG. 2 is a schematic plan view showing an arrangement of electrodes provided on the plasma display panel shown in FIG.
FIG. 3 is a schematic plan view showing a lattice type cell structure as another example of the structure of the discharge cells provided in the plasma display panel according to the present invention.
FIG. 4 is a schematic plan view showing a honeycomb cell structure as another example of the structure of the discharge cells provided in the plasma display panel according to the present invention.
[Explanation of symbols]
1 Plasma display panel
10 Front side board
10a Image display surface
20 Back plate side substrate, one substrate
30, 40, 50 Partition wall
30a Partition wall surface
31, 41, 51 discharge cells
31a One substrate surface
35 phosphor layer

Claims (6)

Two substrates disposed facing each other at a predetermined interval, a partition provided between the substrates to partition a space between the substrates into a plurality, a discharge cell formed by being surrounded by the partition and the substrate, In a plasma display panel comprising a phosphor layer provided inside the discharge cell,
The average particle size of the phosphor constituting the phosphor layer is 0.01 to 1.0 μm, and the ratio of the volume of the phosphor layer in the discharge cells is 10 to 40% by volume. Plasma display panel. The plasma display panel according to claim 1,
The plasma display panel according to claim 1, wherein a volume ratio of the phosphor layer in the discharge cell is 10 to 30% by volume. The plasma display panel according to claim 1 or 2,
When the partition wall surface facing the inside of the discharge cell and one of the substrate surfaces and a phosphor layer coatable surface that can be coated with a phosphor layer,
A plasma display panel, wherein the amount of the phosphor constituting the phosphor layer is 20 g / m ² or more and 100 g / m ² or less per unit area of the phosphor layer coverable surface. Two substrates disposed facing each other at a predetermined interval, a partition provided between the substrates to partition a space between the substrates into a plurality, a discharge cell formed by being surrounded by the partition and the substrate, In a plasma display panel comprising a phosphor layer provided inside the discharge cell,
The phosphor constituting the phosphor layer has an average particle size of 0.01 to 1.0 μm, and a ratio of a volume occupied by the phosphor in the phosphor layer is 30 to 80% by volume. Plasma display panel. The plasma display panel according to claim 4,
The volume ratio of the phosphor in the phosphor layer is 40 to 80% by volume. The plasma display panel according to any one of claims 1 to 5,
A plasma display panel, wherein the phosphor is manufactured by a liquid phase synthesis method in which a phosphor material is reacted in a liquid phase.

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