Electric lamp and discharge devices – With luminescent solid or liquid material – Vacuum-type tube
Reexamination Certificate
1998-11-23
2003-10-07
Patel, Vip (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
Vacuum-type tube
C313S495000, C313S422000
Reexamination Certificate
active
06630782
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an image display apparatus, and more particularly relates to a thin image display apparatus used for a video camera and the like.
BACKGROUND OF THE INVENTION
Conventionally, cathode ray tubes have been used mainly as image display apparatuses for color televisions, personal computers and the like. However, in recent years, image display apparatuses have been required to be improved for space saving, for portability or for some other demands. In order to satisfy these demands, various types of thin image display apparatuses have been developed and commercialized.
Under these circumstances, various types of thin image display apparatuses have been researched and developed recently. In particular, liquid crystal displays and plasma displays have been developed actively. The liquid crystal displays have been applied to various types of products such as portable personal computers, portable televisions, video cameras, car-navigation systems and the like. In addition to that, the plasma displays have been applied to products such as large-scale displays, for example, 20 inch-displays or 40-inch displays.
However, there are some problems for the displays. A liquid crystal display has a narrow visual angle and a slow response. Regarding a plasma display, high brightness can't be obtained and the consumed electricity is large. A thin image display apparatus called a field emission image display apparatus has attracted considerable attention to solve these problems. The field emission image display apparatus uses field emission, i.e. a phenomenon in which electrons are emitted in a vacuum at room temperature. The field emission image display apparatus is a spontaneous luminescent type, and therefore it is possible to obtain a wide visual angle and high brightness. The spontaneous luminescent type apparatus does not require back lighting, and thus, it consumes less electric power.
An image display apparatus disclosed in Unexamined Published Japanese Patent Application (Tokkai-Hei) No. 2-33839 is known as a flat spontaneous light emission type image display apparatus with high-quality images. This is different from the above-mentioned field emission image display apparatus in the structure but uses a linear hot cathode.
FIG. 9
is a perspective exploded view showing a conventional image display apparatus. The conventional image display apparatus comprises a back electrode
100
, a linear cathode
101
, an electron beam-attracting electrode
102
, a control electrode
103
, a first focusing electrode
104
, a second focusing electrode
105
, a horizontal deflecting electrode
106
, a vertical deflecting electrode
107
, a front glass container
109
a
having a fluorescent layer
108
on the inner surface, and a rear glass container
109
b
. The back electrode
100
, the linear cathode
101
, the electron beam-attracting electrode
102
, the control electrode
103
, the first focusing electrode
104
, the second focusing electrode
105
, the horizontal deflecting electrode
106
and the vertical deflecting electrode
107
are contained between the rear glass container
109
b
and the front glass container
109
a
(the fluorescent layer
108
side), and the space where those components are contained between the glass containers (
109
a
,
109
b
) is maintained under a vacuum.
In the image display apparatus, electron beams are formed in a matrix by the linear cathode
101
and the electron beam-attracting electrode
102
, and focused by using the first focusing electrode
104
and the second focusing electrode
105
. Then, the electron beams are deflected by the horizontal deflecting electrode
106
and the vertical deflecting electrode
107
before being landed on predetermined positions of the fluorescent layer
108
. The control electrode
103
controls the electron beams over time, and adjusts each electron beam independently according to picture signals for displaying pixels.
Respective components for the image display apparatuses in the conventional technique are thin and flat plates. Therefore, an image display apparatus provided by combining these components has a thin body and a flat screen.
In the conventional image display apparatus, however, forming every electrode with accuracy is difficult, since the first and second focusing electrodes (
104
,
105
) functioning to focus electron beams are made of conductive plates provided with slender holes, while the horizontal and vertical deflecting electrodes (
106
,
107
) to deflect the electron beams are made of two interdigital conductive plates.
More specifically, as the first focusing electrode
104
and the second focusing electrode
105
are conductive plates provided with slender holes, waviness or warping may occur in each electrode. The horizontal deflecting electrode
106
and the vertical deflecting electrode
107
are interdigital conductive plates formed by etching plate components. Therefore, waviness or warping may occur in each interdigital conductive plate as well. Moreover, each deflecting electrode is made of two interdigital conductive plates, and thus, relative deflections may occur in the deflecting electrodes for some reason.
Tokkai Hei No. 2-33839 discloses a method for manufacturing a laminated electrode, in which the laminated electrode comprises electrodes comprising separate plural conductive plates, such as the control electrode
103
and the deflecting electrodes
106
,
107
. When the conductive flat plates are etched to have a slit pattern in such a case, the plates are initially etched in a continuous state. These electrode plates are adhered, laminated and fixed while being insulated in a predetermined order. After that, a predetermined part is cut by using laser beams or some other means, if insulation is required in the same surface. The process of the method, however, has some problems as follows. Pattern-etching does not support the growing demand for precision, since it is difficult to treat holes whose diameter is not more than the plate thickness or residual margins. In order to stabilize the surfaces, adhesion margins should be formed with an appropriate pitch on the entire plate surface, but this is another obstacle to precision. The plates cannot be processed to be so thin for keeping surface accuracy and stiffness, but when a thick plate is etched, the configuration at the etched section is varied, which may cause errors in electron lenses. When plates etched in different shapes are adhered and laminated, the balance in the stress is lost, and warping and waviness arise. As a result, a flat surface is difficult to obtain.
When waviness or warping arises in the focusing electrodes and deflecting electrodes composing a conventional image display apparatus, it will do harm for focusing and deflection of electron beams. As a result, appropriate control of the electron beams becomes difficult, and the landing positions of the electron beams will be deviated. In such an image display apparatus, landing an electron beam on a predetermined position of the fluorescent layer
108
is difficult. As a result, problems such as error irradiation may increase, and thus, image quality of the image display apparatus will deteriorate, and an image display apparatus with high resolution cannot be easily obtained.
SUMMARY OF THE INVENTION
In order to solve the above-mentioned problems, this invention is directed to providing an image display apparatus comprising an electrode having a flat surface free from waviness or warping. Such an image display apparatus appropriately controls focusing and deflection of electron beams and prevents problems such as deviation of the electron beam landing positions and error irradiation. The image display apparatus will have excellent images and high resolution.
In order to achieve the above purposes, an image display apparatus of this invention comprises, in a vacuum container whose inside is kept under vacuum, a fluorescent layer, an electron emission source having an electron source, and electrodes for controlling
Imai Kanji
Kurata Takatsugu
Nakatani Toshifumi
Matsushita Electric - Industrial Co., Ltd.
Merchant & Gould P.C.
Patel Vip
Williams Joseph
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