US3827776A - Method of fabricating a gas discharge display device having an alkali metal atomic layer - Google Patents

Method of fabricating a gas discharge display device having an alkali metal atomic layer Download PDF

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Publication number
US3827776A
US3827776A US00262480A US26248072A US3827776A US 3827776 A US3827776 A US 3827776A US 00262480 A US00262480 A US 00262480A US 26248072 A US26248072 A US 26248072A US 3827776 A US3827776 A US 3827776A
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United States
Prior art keywords
alkali metal
dielectric layer
display device
panel
electrodes
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Expired - Lifetime
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US00262480A
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English (en)
Inventor
N Nakayama
M Osawa
K Mizuko
I Takahashi
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Fujitsu Ltd
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Fujitsu Ltd
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Priority claimed from JP4470871A external-priority patent/JPS5214956B1/ja
Priority claimed from JP7286271A external-priority patent/JPS5422068B2/ja
Application filed by Fujitsu Ltd filed Critical Fujitsu Ltd
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Publication of US3827776A publication Critical patent/US3827776A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J11/00—Gas-filled discharge tubes with alternating current induction of the discharge, e.g. alternating current plasma display panels [AC-PDP]; Gas-filled discharge tubes without any main electrode inside the vessel; Gas-filled discharge tubes with at least one main electrode outside the vessel

Definitions

  • the present invention relates to a display device utilizing gas discharge known as a plasma display panel, and the method for manufacturing the same. More particularly, this invention relates to a novel display device utilizing gas discharge, which is improved so as to discharge with a relatively low firing voltage.
  • the voltage applied to the electrodes is divided into a voltage across the dielectric layers and a voltage acrossthe gas cell medium.
  • the firing voltage V a gas discharge is produced in the gaseous medium.
  • the main factors determining the firing voltage in the plasma display panel are the composition of ionizable gas, and the dielectric layer which covers the electrodes.
  • the composition of ionizable gas and the dielectric layer which covers the electrodes.
  • every possible known means have already been tried and a decrease of the firing voltage by improving the composition of ionizable gas, cannot be anticipated.
  • various improvements have been tried, and a recent device using a low melting temperature glass can operate with a voltage of 250 300 volts.
  • the conventional device using a glass seat requires 300 700 volts for its operation.
  • the main factors determining the firing voltage (V) are (a) the product of the pressure of the gas and the length of the discharge gap and (b) the secondary electron emissivity (y) on the surface of the dielectric layer. And when this secondary electron emissivity ('y) on the surface of the dielectric layer increases, the firing voltage (V,) decreases.
  • the dielectric layer covering the electrodes a material having a high dielectric constant and at the same time a large secondary electron emissivity is recommended as the dielectric layer covering the electrodes.
  • This dielectric layer requires excellent characteristics in its softening temperature, fluidity, mutual diffusion characteristics with the electrode material, its thermal expansion, thermal resistivity, and optical transparency.
  • Some type of low melting temperature glass was used conventionally, because such glass satisfied the above-mentioned characteris tics.
  • the firing voltage of the display device, using such low melting temperature glass could be decreased to about250 300 V.
  • the reason for this decrease of the firing voltage in a device using low melting temperature glass is that the large lead (Pb) component included in such glass presents a relatively high secondary electron emissivity.
  • the alkali component of the low melting temperature glass, used as the dielectric layer is an important factor.
  • the component of alkali metal is increased the thermal expansion coefficient increases. And then the difference in the expansion coefficient between a substrate and a dielectric layer including alkali-metal increases, the mechanical and electrical characteristics of the displaying device deteriorate.
  • the present invention provides a means for forming an element which raises the secondary electron emissivity on the dielectric layer without the abovementioned drawback. That is, a sufficient amount of this element, which raises the secondary electron emissivity, is formed on the surface of the dielectric layer and decreases toward the inside of the dielectric layer. As a result of this, the firing voltage of the displaydevice can be considerably decreased and the drawback, due to the difference in the expansion coefficient between the substrate and the dielectric layer, can be completely overcome.
  • the substrates are first prepared.
  • a group of electrodes are then disposed on the substrates and then the dielectric layers are provided so as to cover the electrodes.
  • This hermetic sealing must be carried out in the air at a temperature of about 400C.
  • the element which raises the secondary electron emissivity for example alkali metal, has a strong chemical activity and reacts with oxygen in the air which results in the deterioration of its secondary electron emissivity. Accordingly, the treatment of a dielectric layer composed of an alkali metal and the assembly of the panel must be carried out in a vacuum or in a non reactive gas. This, of course, complicates the manufacturing process and the cost of the manufacturing equipment becomes high. Further, the'qualities of some kinds of material require that the assembly and the sealing be carried out in the air, which would eliminate the possibility of forming alkali metal layers.
  • one object of the present invention is to provide a display device utilizing gas discharge, which is preferable to the demand of decreasing the firing voltage, and a method for fabricating the same;
  • Another object of the present invention is to provide a display device, utilizing gas discharge, wherein the dielectric material used for covering the electrodes of the display device is improved and the method for fabricating the same.
  • a further object of the present invention is to provide a display device, utilizing gas discharge, which is operable at a firing voltage lower than volts, and a method for fabricating the same.
  • an alkali metal atomic layer for example cesium, having a thickness of less than 100 A is formed on the gas discharge surface of the dielectric layer which covers the electrode.
  • a gas discharge panel is completed in such a manner that the alkali metal layer is exposed to the ionizable gas medium.
  • a further characteristic of the present invention is that a material is used which has very little reactive activity with the alkali metal, which raises the secondary electron emissivity.
  • the alkali metal near the inlet of the vapour rapidly reacts with the dielectric layer and is absorbed near the inlet. Consequently, the amount of the alkali metal which diffuses over the dielectric layer farther from the inlet becomes insufficient and the raising of the secondary electron emissivity can not be anticipated near the exhaust point. It is believed that decreasing the temperature of the treatment will slow the reaction with the dielectric layer.
  • the dielectric layer with materials, such as soda-lime glass, almina, or a silicon compound, which have small activity with the alkali metal.
  • the alkali metal vapour can easily diffuse homogeneously all over the small gap of the sealed panel, repeating the collision and the re-evaporation with the surface of the dielectric layer, and can form the layer having the secondary electron emissivity.
  • a still further feature of the present invention is that it is proposed to form a second dielectric layer from material which has small activity with the element forming the secondary electron emission layer on the dielectric layer.
  • the vapour of alkali metal is introduced into the gap between the second dielectric layers.
  • a surface having a uniform secondary electron emissivity can be obtained even in a panel having a large area.
  • the plasma display panel will have a uniform firing voltage.
  • An additional characteristic of this method is the low melting temperature of glass, which has easy workability and can be used as the material of the first dielectric layer.
  • An important feature in the method of fabricating the plasma display device of the present invention is that the fluid which includes the alkali metal element is introduced into the small gap between the dielectric layers of the panel, the mounting of which is completed by sealing. At this juncture, inlet and exhaust tubes can then be utilized for the purposes of introduction and the exhaustion of the discharge gas.
  • the alkali metal is insulated from the atmosphere and a better surface treatment for raising the secondary electron emissivity can be achieved.
  • the alkali metal distributes itself with high density onto the surface of the dielectric layer and the density of the alkali metal decreases toward the interior of the dielectric layer. Consequently, the effect due to the increase of the heat expansion coefficient, based on the high density of the alkali metal, can be decreased.
  • FIGS. 1 and 1A are partial cross-sectional views of two embodiments of a display device, utilizing gas discharge, of the present invention
  • FIG. 2 is a schematic diagram explaining the method of manufacturing the display device of the present invention.
  • FIGS. 3 and 4 are graphic presentations showing the distribution of the firing voltage of the display device of the present invention.
  • a pair of glass substrates, 1 and 2 provide respectively groups of column electrodes 3 and row electrodes 4 on the inside of their surfaces.
  • the plurality of parallel electrodes 3 and 4 are composed of gold or oxide tin and are transversally positioned relative to each other.
  • Dielectric layers 5 and 6 are provided on the-surfaces of the above-mentioned electrodes.
  • Dielectric layers 5 and 6 are composed of almina or silicon compound and the thickness of said dielectric layers are limited to 0.1 20p.
  • alkali metal atomic layers 7 and 8 particularly cesium atomic layers less than 100 A, are disposed.
  • a gaseous medium 9 is composed between the above-mentioned alkali metal atomic layers 7 and 8.
  • almina, silicon dioxide or silicon nitride are preferably used as the material of dielectric layers 5 and 6.
  • the reason for this is understood on the assumption that alkali metal atomic layers 7 and 8 are disposed on dielectric layers 5 and 6.
  • the display device utilizing gas discharge with the dielectric layer including only almina clearly requires a firing voltage higher than that of the usual display device with a dielectric layer of low melting temperature glass.
  • the firing voltage of said dielectric layer decreases to about V, which is a wonderful value.
  • the alkali metal atom layer can be disposed on the surface of the dielectric layer even after assembling the display device. Many other materials could be considered for the insulating material.
  • the above-mentioned almina, silicon dioxide or silicon nitride are the most preferable materials because they satisfy all the demands of manufacturing technology, expansion coefficient, thermal flow properties and dielectric constant; can withstand voltage etc., and fits to the alkali metals.
  • the dielectric layers 5 and 6 it is preferable to make the dielectric layers 5 and 6 thin, so as to decrease the unuseful voltage participated thereon.
  • the dielectric layers 5 and 6 become less than 0.lp., there is a possibility of producing a dielectric breakdown.
  • the thickness of the dielectric layers 5 and 6 exceed 20p, the firing voltage increases, the construction of the surface of the dielectric layer becomes complex and the manufacturing tech nology becomes difficult. Accordingly, it is preferable to limit the thickness of the dielectric layers to a value between 0.1 20p" Alkali metal atomic layers 7 and 8 should not decrease the surface resistance of the dielectric layers 5 and 6.
  • the wall surface exposed to gaseous medium 9 should have a high insulation resistance whether alkali metal atomic layers 7 and 8 exist or not.
  • the thickness of the above-mentioned alkali metal atomic layers 7 and 8 are maintained at less than 100 A.
  • a high secondary electron emissivity is, therefore, obtained on the wall surface, thus maintaining the surface resistance of the wall surface in the best condition. This is due to the fact that, when the alkali atomic layers are maintained at less than 100 A, a discontinuous condition appears on the layer and they become non conductive to the surface direction.
  • second dielectric layers, 5a and 6a are formed on the dielectric layers 5 and 6 when layers 5 and 6 are composed of low melting temperature glass.
  • the second dielectric layers, 5a and 6a are composed of a material, such as almina or silica, which have a low reactivity with the alkali metal.
  • These second dielectric layers are coated with the above-mentioned alkali metal layers having a homogeneous and high secondary emissivity over 'a wide range.
  • the next explanation will concern a preferable method for manufacturing the display device utilizing gas discharge.
  • the groups of electrodes 3 and 4 are first formed by using a well-known method, for example, a vacuum evaporating coating of gold or screen printing method. Then the dielectric layers 5 and 6, composed of silicon compound or almina, are provided, except for the portions connected to its terminals, by using a sputtering means. After that the substrates l and 2 are disposed face to face with a gap of about 300p. therebetween, and the peripheral portion of the substrates is sealed with the low melting temperature glass. Next, tip tubes 11 and 12, which are connected to the above-mentioned air gap, are provided for forming the alkali metal atomic layers as shown in FIG. 2. Tip tubes 11 and 12 are connected to two corner portions on panel 10.
  • Tip tube 11 is connected, via valves V, and V respectively, to an exhaust device 13 and a gas supply device 14.
  • Tip tube 12 is connected to a vessel 15 reserving, for example, cesium (Cs).
  • Cs cesium
  • the display device utilizing gas discharge, which is fabricated by the above-mentioned method operates at a voltage lower than 100 V.
  • a voltage lower than 100 V For example, we fabricated the panel by substrates disposed almina layer having the thickness of about 3n, for covering the electrodes, preheated to C while exhausting, heated the cesium vessel to C, carried out the abovementioned process for 5 hours, and obtained the cesium atomic layers having a thickness less than 100 A on the almina layers.
  • This completed display device could discharge at a firing voltage of 80 V i 10 V over all portions which the the cells at crossing points between the column and row electrodes included in a display area of about 10 cm X 10 cm, and no inconvenience was found in its memory function. This reason is that the alkali metal atomic layer, particularly the cesium atomic layer, of the present invention is diffused homogeneously over all the dielectric layer, and enhances the secondary electron emissivity of the surface.
  • the secondary electron emission layer are formed by introducing the liquid which includes the alkali metal element.
  • Alkali for example, makes a liquid compound which is not reactive to the dielectric layer at ordinary temperature; can be introduced to the gap which is composed between the dielectric layers of the panel after mounting; is reberated by the heat treatment; and allows formation of the secondary electron emission layers on the surfaces of the dielectric layers.
  • a solution of alkali-metal alcoholate in alcohol is introduced into the panel, then the solvent is removed out of the panel and a homogeneous layer of al coholate is formed on the surfaces.
  • homogeneous secondary electron emission layers of alkali metal can be obtained. When this occurs the by-product of the heat decomposition is exhausted as a hydrocarbon.
  • alkali metal is used as a substance forming the secondary electron emission layers.
  • the other material such as alkali earth metal and lead (Pb), can also be used as the substance forming the secondary electron emission layers.
  • the method for fabricating the plasma display device of the present invention comprises the process of forming a layer having a high secondary electron emissivity on the dielectric layer. This 7 is done by introducing the fluid, in liquid including alkali metal into the panel after assembling. We will now compare the distribution of the firing voltage of a panel having dielectric layer composed of low melting temperature glass with that of almina.
  • FIG. 3 is a diagram showing the distribution of the equi-firing voltage curves when the above-mentioned process is performed directly on the dielectric layer composed of low melting temperature glass.
  • the inlet of the alkali metal is shown as A and the exhaust is shown as B.
  • FIG. 3 shows that the firing voltage decreases by forming the secondary electron emission layer of the present invention. That is, when the secondary electron emission layer is not formed, a firing voltage greater than 150 V is required all over the panel surface. When the secondary electron emission layer exists, the firing voltage can be decreased, to less than 100 V, near the cesium gas inlets.
  • the phenomena shown in FIG. 3 is applicable to a panel having a relatively small area. However, in a large area panel having the dielectric layer of low melting temperature glass which easily absorbs the cesium, it is very difficult to homogeneously decrease the firing voltage all over the surface. Then, as mentioned above, the second dielectric layers are provided, as shown in FIG. 1A.
  • FIG. 4 shows the distribution of the equi-firing voltage in the case of providing the second dielectric layer.
  • the decrease of the firing voltage is realized homogeneously at 80 90 V all over the surface, as shown in FIG. 4.
  • the portion having a variation of the firing voltage is limited to that near the outlet,
  • the firing voltage can be decreased by 50 60% by forming the secondary electron emission layers. Further a homogeneous decrease of the firing voltage can be realized all over a large area surface by providing the second dielectric layer on the surface of the first.
  • the present invention relates to a display device, utilizing gas discharge, whose firing voltage can be surprisingly decreased, and the method for fabricating the same.
  • a firing voltage lower than 100 V can at low cost of device be used as the driving circuit through an integrated circuit. It, therefore, develops the field of application of this kind of display device.
  • Application of the methods used is not limited to above-mentioned device. Rather they can be applied to any display device in which groups of gas discharge electrodes are disposed in a condition insulated from the ionizable gas medium.
  • a method for fabricating a display device utilizing gas discharge comprising the steps of:
  • a pair of insulating substrates at least one of which providing a group of electrodes on an inside surface; coating a dielectric substance on said group of electrodes; forming a panel by positioning said pair of insulating substrates in spaced parallel relation having inside surfaces opposite each other with a gap therebetween; forming an hermetic seal at a periphery of said panel;
  • a method for fabricating a display device utilizing gas discharge comprising the steps of:

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Gas-Filled Discharge Tubes (AREA)
US00262480A 1971-06-21 1972-06-14 Method of fabricating a gas discharge display device having an alkali metal atomic layer Expired - Lifetime US3827776A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP4470871A JPS5214956B1 (enrdf_load_stackoverflow) 1971-06-21 1971-06-21
JP7286271A JPS5422068B2 (enrdf_load_stackoverflow) 1971-09-18 1971-09-18

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FR (1) FR2143245B1 (enrdf_load_stackoverflow)
GB (1) GB1390105A (enrdf_load_stackoverflow)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3932920A (en) * 1972-10-02 1976-01-20 Owens-Illinois, Inc. Method of manufacturing a multiple gaseous discharge display/memory panel having improved voltage characteristics
US4198585A (en) * 1975-11-19 1980-04-15 Fujitsu Limited Gas discharge panel
US4235001A (en) * 1975-09-17 1980-11-25 Haruhiro Matino Gas display panel fabrication method
US4731560A (en) * 1970-08-06 1988-03-15 Owens-Illinois Television Products, Inc. Multiple gaseous discharge display/memory panel having improved operating life
US5938494A (en) * 1996-11-20 1999-08-17 Fujitsu Limited Method for producing a plasma display panel
US6051928A (en) * 1996-12-31 2000-04-18 Samsung Display Devices Co., Ltd. Plasma display device with ferroelectric dielectric layer
US20020190926A1 (en) * 2001-06-19 2002-12-19 Hiroshi Kajiyama Plasma display panel
CN104850001A (zh) * 2014-02-14 2015-08-19 精工爱普生株式会社 原子室及制造方法、量子干涉装置、振荡器、设备和移动体

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3716742A (en) * 1970-03-03 1973-02-13 Fujitsu Ltd Display device utilization gas discharge

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3716742A (en) * 1970-03-03 1973-02-13 Fujitsu Ltd Display device utilization gas discharge

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4731560A (en) * 1970-08-06 1988-03-15 Owens-Illinois Television Products, Inc. Multiple gaseous discharge display/memory panel having improved operating life
US3932920A (en) * 1972-10-02 1976-01-20 Owens-Illinois, Inc. Method of manufacturing a multiple gaseous discharge display/memory panel having improved voltage characteristics
US4235001A (en) * 1975-09-17 1980-11-25 Haruhiro Matino Gas display panel fabrication method
US4198585A (en) * 1975-11-19 1980-04-15 Fujitsu Limited Gas discharge panel
US5938494A (en) * 1996-11-20 1999-08-17 Fujitsu Limited Method for producing a plasma display panel
US6051928A (en) * 1996-12-31 2000-04-18 Samsung Display Devices Co., Ltd. Plasma display device with ferroelectric dielectric layer
US20020190926A1 (en) * 2001-06-19 2002-12-19 Hiroshi Kajiyama Plasma display panel
US6816134B2 (en) * 2001-06-19 2004-11-09 Hitachi, Ltd. Plasma display panel
CN104850001A (zh) * 2014-02-14 2015-08-19 精工爱普生株式会社 原子室及制造方法、量子干涉装置、振荡器、设备和移动体
US20150244382A1 (en) * 2014-02-14 2015-08-27 Seiko Epson Corporation Atomic cell, manufacturing method for atomic cell, quantum interference device, atomic oscillator, electronic apparatus, and moving object
US9673830B2 (en) * 2014-02-14 2017-06-06 Seiko Epson Corporation Atomic cell, manufacturing method for atomic cell, quantum interference device, atomic oscillator, electronic apparatus, and moving object
CN104850001B (zh) * 2014-02-14 2018-11-27 精工爱普生株式会社 原子室及制造方法、量子干涉装置、振荡器、设备和移动体

Also Published As

Publication number Publication date
GB1390105A (en) 1975-04-09
FR2143245A1 (enrdf_load_stackoverflow) 1973-02-02
DE2230373A1 (enrdf_load_stackoverflow) 1972-12-28
DE2230373B2 (de) 1975-07-17
FR2143245B1 (enrdf_load_stackoverflow) 1977-12-23

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