Electric lamp and discharge devices – With luminescent solid or liquid material – Vacuum-type tube
Reexamination Certificate
1999-01-19
2002-09-17
Patel, Ashok (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
Vacuum-type tube
C313S309000, C313S310000, C313S311000
Reexamination Certificate
active
06452328
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electron emission device used in a so-called field emission type display apparatus, a production method of the electron emission device, and a display apparatus using the electron emission device.
2. Description of the Prior Art
Recently, the development of display devices has been directed to make the devices thinner. To achieve this special attention has been paid to, a so-called field emission type display (hereinafter, referred to as FED).
As shown in
FIG. 1
, in an FED, for one pixel, there are provided a spindt type electron emission device
100
and a fluorescent panel
101
formed opposite to this electron emission device
100
. Such pixels are formed in a matrix to constitute a display.
The portion corresponding to one pixel includes an electron emission device
100
having: a cathode electrode
103
formed on a cathode panel
102
; an insulation layer
104
formed on the cathode electrode
103
; a gate electrode
105
layered on this insulation layer
104
; a hole portion
106
formed through the gate electrode and the insulation layer
104
; and an electron emission emitter
107
formed inside the holde portion
106
. Moreover, this FED includes a fluorescent plane
101
arranged so as to oppose the electron emission device
100
and having a front panel
108
, an anode electrode
109
formed on this front panel
108
, and a fluorescent body
110
. Furthermore, this FED is constituted so that a predetermined voltage is applied to the cathode electrode
103
, the gate electrode
105
, and the anode electrode
109
.
In this FED, the electron emitter
107
is made from material such as W, Mo, and Ni processed approximately into a small conical shape with its tip positioned at a predetermined distance from the gate electrode. This electron emission device
100
emits electrons from the tip of the electron emitter
107
and includes a number of the electron emitters
107
.
In the FED having such a configuration, a predetermined electric field is generated between the cathode electrode
103
and the gate electrode
105
. This causes electrons to be emitted from the tip of the electron emitter
107
. The electrons emitted strike the fluorescent body
110
formed on the anode electrode
109
. This excites the fluorescent body
110
to emit light. The FED controls the quantity of the electrons emitted from the electron emitter
107
for each pixel to display a desired image.
More specifically, in the FED, the hole portion
106
has an opening dimension of about 1 micrometer or less; and the electron emitter
107
has a height of 1 micrometer or less and the base of electron emitter
107
has a curvature radius in the order of several tens of nm. Moreover, in the FED, one pixel has several tens to several thousands of electron emitters
107
. For example, in a display of XGA class in which the number of pixels is 1024×768× (RGB), it is necessary to provide 100 to 100000 millions of electron emitters
107
.
A voltage of several tens of volts is applied from the cathode electrode
103
to the gate electrode
105
, so as to generate an electric field in the order of 10
7
V/cm between the gate electrode
105
and the tip of the of the electron emitters
107
. Moreover, a voltage on the order of 200 to 5000 V is applied to the anode electrode
109
, so that electrons emitted from the electron emitter
107
strike the fluorescent plane
101
.
However, the FED described above having the electron emitters
107
of the spindt type has problems as follows.
First of all, the spindt type electron emitter
107
is formed on a microscopic scale, requiring a submicron accuracy. Accordingly, it is necessary to employ a process and apparatus identical to those for producing an integrated circuit (IC) to form the FED. However, for example, when preparing a display having a screen of 17-inch size in a diagonal direction, the apparatus size becomes too large, significantly increasing the costs. Besides, if the display is to have a large size, the production yield is remarkably lowered because the electron emitters
107
need be formed uniformly over the entire cathode panel surface.
Secondly, the electron emitter
107
is made from a material such as W, Mo, and Ni, and an electric field in the order of 10
7
V/cm is required between the cathode electrode
103
and the gate electrode
105
. In order to satisfy these parameters while maintaining the small voltage applied, the interval between the gate electrode
105
and the electron emitter
107
must be a submicron or less. However, it is quite difficult to form a submicron interval without short-circuiting the gate electrode
105
and the cathode electrode
103
. Thus, the production yield is significantly lowered.
Thirdly, the material W, Mo, or Ni constituting the electron emitters
107
, for example, is eroded by the collision of ions generated from a residual gas and from the fluorescent body
110
and is rapidly deteriorated. Thus, in the FED having this spindt type electron emitter
107
, the vacuum degree of the portion containing the electron emitter
107
must be reduced. More specifically, it is necessary to maintain a vacuum 10 times lower than the vacuum degree of an ordinary cathode ray tube
10
″ to 10−7 Torr. In order to reach such a low vacuum, it is necessary to greatly increase the mechanical strength of the display, preventing reduction in the apparatus size including the thickness and weight.
In contrast to this spindt type electron emitters
107
, a there has been suggested an electron emission device including an electron emitter of conductive fine particle type. An electron emission device including this conductive fine particle type electron emitter is disclosed, for example, in PCT/GB96/01858 [1] and WO 97/06549 [2], wherein conductive fine particles are contained in a dielectric layer, i.e., the conductive fine particles are covered with a dielectric layer so as to be arranged via the dielectric layer onto a conductive layer.
This conductive fine particle type electron emitter generates an electric field when a voltage is applied to the conductive layer. This electric field causes the conductive fine particles to emit electrons. In this case, the electron emitter can be formed easier than the aforementioned spindt type and is appropriate for a large-screen flat display that can be produced with a reasonable production cost.
Moreover, U.S. Pat. No. 5,608,283 [3] discloses an electron emission device including a conductive fine particle type electron emitter wherein conductive fine particles are provided on a high-resistance pillar formed on a conductive layer and on the conductive layer via a bonding layer.
This electron emitter also generates an electric field so that the conductive fine particles arranged on the bonding layer, and the like, emit electrons. In this case also, the electron emitter can be produced easier than the aforementioned spindt type and is appropriate for a large-screen flat display that can be produced at a reasonable cost.
On the other hand, in the electron emission device disclosed in Documents [1] and [2], it is necessary to accurately define the thickness of the dielectric layer between the conductive fine particles and the conductive layer as well as the thickness of the dielectric layer covering the conductive fine particles. More specifically, each of these thickness values should be on the order of {fraction (1/10)} to {fraction (1/100)} of the conductive fine particle diameter, i.e., several hundreds Angstroms.
However, it is quite difficult to control the thickness of the dielectric layer on the order of several hundreds of Angstroms. In this electron emission device, if it is impossible to control the thickness of this dielectric layer with a high accuracy, it is impossible to selectively emit electrons, thereby preventing use of the device as a display for displaying an image. That is, such an electron emission device ha
Iida Koichi
Saito Ichiro
Takahashi Tokiko
Kananen Ronald P.
Patel Ashok
Rader & Fishman & Grauer, PLLC
Sony Corporation
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