Electric lamp and discharge devices – With luminescent solid or liquid material – Vacuum-type tube
Reexamination Certificate
2000-02-18
2003-08-05
O'Shea, Sandra (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
Vacuum-type tube
C313S495000, C313S493000, C313S497000
Reexamination Certificate
active
06603255
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image display unit for forming an image, and particularly relates to an image display unit having a voltage introducing terminal for applying a voltage to an anode electrode.
2. Related Background Art
In a conventional image display unit for displaying a dynamic image, etc., a CRT excellent in color reproducibility, responsive speed of an image, price, etc. has been widely used particularly as a color image display unit.
In contrast to this, the CRT has a defect in that the CRT is deep in depth with respect to a display area. Therefore, there is also conventionally a request for the image display unit of a planar type. In recent years, the image display unit of a planar type using a liquid crystal has spread instead of the CRT, but is not of a self light emission type. Therefore, problems exist in that the planar type image display unit must have a back light and field of view depends on angle, etc. Accordingly, the development of a display unit of the planar type and the self light emission type has been desired.
A color plasma display begins to be recently commercialized as such a planar type image display unit of self light emission. However, the principle of light emission in the color plasma display differs from that in the conventional CRT. Therefore, in the present situation, the color plasma display is slightly inferior to the CRT with respect to the contrast of an image, goodness of coloring, etc.
However, in the case of an image display unit using an electron beam similar to the CRT, it can be expected that an image quality equivalent to that in the CRT is obtained. Therefore, the planar type image display unit using the electron beam is researched and developed in many cases.
In these many planar type image display units using the electron beam, plural electron emitting devices of hot cathode and cold cathode types are arranged as a generating source of electrons (hereinafter, simply called an electron source) so that a deflecting space of the electron beam required in the CRT is reduced and the display unit is made thin and flat.
With respect to image display, these planar type image display units use the same principle as the CRT in which an electron emitted from the above electron source is accelerated by a high voltage and is irradiated to a phosphor. Accordingly, it is expected that an image quality similar to that in the CRT is obtained.
For example, Japanese Patent Application Laid-Open No. 4-163833 discloses a planar type image display unit using an electron beam and including a linear hot cathode and a complicated electrode constructional body within a vacuum container.
In these planar type image display units using the electron beam, for example, there is a case in which one portion of the electron beam incident to the phosphor is scattered and collides with an inner wall of the vacuum container, and a secondary electron is emitted and a charge is increased in this emitting portion. In this case, an internal electric potential distribution is distorted and an orbit of the electron beam becomes unstable. Further, an electric discharge is caused within the display unit so that there is a fear that the display unit is deteriorated and broken.
There is a method for forming a charging preventing film in the inner wall of the vacuum container as a method for preventing such an increase in charge. For example, Japanese Patent Application Laid-Open No. 4-163833 discloses a construction in which a conductive layer constructed by a conductive material of high impedance is arranged on a side face of the inner wall of a glass container of the image display unit.
In the image display unit using the electron beam, a high voltage for accelerating electrons is applied between the electron source and the phosphor.
Therefore, when the vacuum container of the image display unit is constructed by glass including Na such as a blue plate glass, etc., Na ions are moved by the above electric field and an electrolytic current is caused.
The vacuum container using glass is formed by joining plural members by frit glass. However, when Na ions flow into the frit glass by the above electrolytic current, PbO included in the frit glass is reduced and Pb is deposited. Accordingly, there is a fear that a crack is caused in the frit glass and no vacuum within the container can be held.
In contrast to this, there is a method in which an electrode is arranged in a suitable position of an outer wall of the vacuum container and an electrolytic current is absorbed into this electrode so that no electrolytic current flows into the frit glass.
For example, Japanese Patent Application Laid-Open No. 4-94038 shows a construction in which a conductive film of low resistance is arranged in a peripheral portion of a face plate and is set to a ground electric potential and no electrolytic current flows into the frit glass. U.S. Pat. No. 5,357,165 discloses a construction in which a band-shaped electrode for forming the gradient of an electric potential by flowing a current is arranged in a side wall of the vacuum container.
In contrast to this, in the planar type image display unit utilizing the above electron beam described in Japanese Patent Application Laid-Open No. 4-163833, the deflecting space of the electron beam required in the conventional CRT is greatly reduced by using plural linear hot cathodes. However, the complicated electrode constructional body such as a horizontal deflecting electrode, a vertical deflecting electrode, etc. for deflecting the electron beam to plural pixels (phosphor) is included within the container. Therefore, it cannot be avoided that the display unit has a certain thickness (about several ten mm). However, in recent years, for example, the development of a display unit of a super thinner type similar to that of a liquid crystal display is also required in the planar type image display unit utilizing the electron beam as a portable information terminal device, etc.
The present applicant already made many proposals with respect to a surface conduction electron emitting device and a planar type image display unit using this surface conduction electron emitting device to achieve the planar type image display unit of a super thin type utilizing the electron beam. For example, such proposals are described in Japanese Patent Application Laid-Open No. 7-235255.
This electron emitting device is simple in construction and many electron emitting devices can be integrated and formed in a large area. Therefore, one electron emitting device can be also formed with respect to one pixel (phosphor), land it is possible to remove the deflecting space of the electron beam required in the planar type image display unit utilizing the electron beam described in the above Japanese Patent Application Laid-Open No. 4-163833, or the normal CRT. Therefore, the electron emitting device can be used in a very thin planar type image display unit.
Further, a planar type image display unit of a super thin type using a field emitter type electron emitting device (hereinafter, called an FE type device) as the electron source is described in Japanese Patent Application Laid-Open No. 5-114372.
The planar type image display unit of a super thin type capable of relatively stably introducing a high voltage is shown by an introducing structure of the high voltage in the above-mentioned conventional display unit (FIG.
11
). In accordance with
FIG. 11
, a face plate
2
is formed oppositely to a rear plate
1
, and a low voltage electrode
12
for a wiring electrode for scanning and a wiring electrode for applying a signal voltage is formed in the electron emitting device in the rear plate
1
. A phosphor, each layer of a metal back and a phosphor pull-out electrode
6
are formed in the face plate
2
. A bar-shaped electrode
9
and an elastic body
28
connected to the bar-shaped electrode
9
from a side of the rear plate
1
are sequentially connected to this phosphor pull-out electrode
6
. The bar-shaped electro
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
O'Shea Sandra
Ton Anabel
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