Display device with plate-like control electrodes

Details Display device with plate-like control electrodes Display device with plate-like control electrodes

2003-01-08

2004-11-23

Patel, Ashok (Department: 2879)

Electric lamp and discharge devices

With luminescent solid or liquid material

Vacuum-type tube

C313S495000, C313S496000, C313S309000, C313S310000, C313S351000, C313S293000

Reexamination Certificate

active

06822388

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a display device which utilizes emission of electrons into vacuum, and more particularly to a display device which enhances stable display characteristics by mounting cathode lines which have electron sources and control electrodes which control an electron pulling quantity (electron emission quantity) from the electron sources with high accuracy.
A color cathode ray tube has been popularly used conventionally as a display device which exhibits excellent properties such as high luminance and high definition. However, along with a demand for high image quality in recent information processing apparatuses and television broadcasting, a demand for a planar display (panel display) which is light-weighted and requires a small-space while ensuring properties such as high luminance and high definition is increasing.
As a typical example of such a planar display, a liquid crystal display device, a plasma display device and the like have been commercialized. Further, as the planar display device which can realize the high luminance, various types of panel-type display devices including a display device which makes use of emission of electrons from an electron source into vacuum (hereinafter, referred to as an electron emission type display device or a field emission type display device), an organic EL display which is characterized by its low power consumption and the like are expected to be commercialized soon.
Among such panel-type display devices, as the field emission type display device, a display device having an electron emission structure which is proposed by C. A. Spindt et al., a display device having a metal-insulator-metal (MIM) type electron emission structure, a display device having an electron emission structure which makes use of an electron emission phenomenon based on a quantum theory tunneling effect (also referred to as a surface conductive type electron source), a display device which makes use of an electron emission phenomenon possessed by a diamond film, a graphite film or a carbon nanotube and the like have been known.
The field emission type display device includes a back panel which forms cathode lines having field emission type electron sources and control electrodes on an inner surface thereof and a front panel which forms anodes and phosphors materials on an inner surface thereof which faces the back panel in an opposed manner, wherein the display device is constituted by laminating both panels while inserting a sealing frame between inner peripheries of both panels and by evacuating the inside thereof. Further, to hold a distance between the back panel and the front panel at a given value, distance holding members are provided between the back panel and the front panel.
FIG. 17
is a plan view of a back panel for explaining the schematic constitution of a field emission type display device. Here,
FIG. 17
is constituted of a schematic view as viewed from a front panel side. With respect to the constitution which is explained in conjunction with the drawing, a technique which is relevant to fixing of control electrodes is the constitution which the applicant of the present invention has conceived in the process of reviewing the present invention and hence, the technique does not constitute a known technique. The back panel includes a plurality of cathode lines
2
having electron sources and a plurality of control electrodes
4
on a back substrate
1
which is preferably be made of glass, alumina or the like. A large number of cathode lines
2
extend in one direction and are arranged in parallel in another direction which crosses one direction on the back substrate
1
. The cathode lines
2
are patterned by printing a conductive paste including silver or the like and cathode-line lead lines
20
are pulled to the outside of a sealing frame
9
from end portions of the cathode lines
2
.
The control electrodes
4
shown in
FIG. 17
are constituted of plate members which are manufactured as separate members. The control electrodes
4
are arranged above and close to the cathode lines
2
having the electron sources. A large number of control electrode
4
extend in the above-mentioned another direction and are arranged in parallel in the above-mentioned one direction. The control electrodes are explained as plate-like control electrodes
4
hereinafter. These plate-like control electrodes
4
are fixed to the back substrate
1
at fixing portions provided outside a display region AR using a pressing members
6
which are formed of an insulator such as a glass material. In the vicinity of the fixing portions, leads (plate-like control electrode leads)
50
are connected to the plate-like control electrodes
4
and are pulled out to the outside of the sealing frame
9
. Pixels are formed on respective crossing portions between the cathode lines (electron sources provided to the cathode lines)
2
and the control electrodes
4
. Here, the sealing frame
9
may be provided with a function of the pressing member
6
.
An emission quantity (including ON and OFF) of electrons from the electron sources provided to the cathode lines
2
is controlled based on a potential difference between the cathode lines
2
and the control electrodes
4
. On the other hand, the front panel not shown in the drawing includes anodes and phosphors on a front substrate which is made of a light-transmitting material such as glass. The phosphors are formed corresponding to the pixels formed at the crossing portions between the cathode lines
2
and the plate-like control electrodes
4
.
The inside of the display device sealed by the sealing frame
9
is evacuated to a vacuum of 10
−5
-10
−7
Torr, for example. Each crossing portion between the control electrode
4
and the cathode line
2
includes electron passing holes not shown in the drawing and these electron passing holes allow the electrons emitted from the electron source of the cathode line
2
to pass therethrough toward the anode side. The above-mentioned electron source is, for example, constituted of carbon nanotubes (CNT), diamond-like carbon (DLC) or other field emission cathode.
On the back substrate
1
on which the cathode lines
2
are formed, it is necessary to mount the plate-like control electrodes
4
at a given distance over the whole area of the display region AR with respect to the cathode lines
2
.
FIG. 18
is a plan view for explaining the shape of the plate-like control electrodes
4
as parts before mounting them on the back substrate
1
. The structure of the plate-like control electrodes
4
shown in
FIG. 18
, the manufacturing method and the mounting method of the plate-like control electrodes
4
, and the detailed structure of the plate-like control electrodes
4
are conceived by the applicant of the present application in the stage of reviewing the present invention and hence, they do not constitute known techniques. The plate-like control electrodes
4
are formed usually such that an aluminum-based or an iron-based thin plate is formed into a large number of stripe-shaped thin plates and a large number of electron passing holes are formed in these stripe-like thin plates by etching using a photolithography technique.
The plate-like control electrodes
4
which constitute parts are in a state that they are held by a frame
40
. At the time of mounting the plate-like control electrodes
4
to the back substrate
1
, the plate-like control electrodes
4
are positioned on the cathode lines
2
formed on the back substrate
1
together with the frame
40
, and the outside of the display region AR is fixed by the pressing member
6
(FIG.
17
). Thereafter, the frame
40
is cut and removed.
As explained in conjunction with
FIG. 18
, the plate-like control electrodes
4
are formed of thin plates formed by etching having a small thickness (approximately 0.05 mm) and hence, there exists a portion where a mechanical strength is sharply changed (a stress concentration portion to which a force is applied from outside) in the v

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