Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Reexamination Certificate
2001-03-09
2003-06-17
Philogene, Haissa (Department: 2821)
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
C313S497000
Reexamination Certificate
active
06580223
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to a flat-type display such as a cold cathode field emission display.
As an image display device that can be substituted for a currently mainstream cathode ray tube (CRT), flat-screen (flat-panel) displays are studied in various ways. Such flat-panel displays include a liquid crystal display (LCD), an electroluminescence display (ELD) and a plasma display (PDP). There has been also proposed a cold cathode field emission display capable of emitting electrons into a vacuum from a solid without relying on thermal excitation, a so-called a field emission display (FED), and it attracts attention from the viewpoint of the brightness of a display screen and low power consumption.
FIG. 82
shows a typical constitution of the cold cathode field emission display (to be sometimes abbreviated as “display” hereinafter), and
FIG. 83
shows a schematic exploded view of some portions of a first panel
10
and a second panel
20
. In this display, the first panel (cathode panel)
10
and the second panel (anode panel)
20
are arranged to face each other and bonded to each other in their circumferential portions through a frame (not shown), so that a closed space between these two panels
10
and
20
constitutes a vacuum space. The first panel
10
has cold cathode field emission devices (to be sometimes referred to as “field emission device” hereinafter) as electron-emitting elements.
FIG. 82
shows, as one example, so-called Spindt-type field emission devices each of which has electron-emitting portion
16
constituted of a conical electron emission electrode
16
A. The Spindt-type field emission device comprises a stripe-shaped cathode electrode
12
formed on a support member
11
, an insulating layer
13
, a stripe-shaped gate electrode
14
formed on the insulating layer
13
, and the conical electron emission electrode
16
A formed in an opening portion
15
formed in the gate electrode
14
and the insulating layer
13
. Generally, a predetermined number of such electron emission electrodes
16
A having a predetermined arrangement are formed to correspond to one of phosphor layers
22
to be described later. A relatively negative voltage (scanning signal) is applied to the electron emission electrode
16
A from a cathode-electrode driving circuit
34
through the cathode electrode
12
, and a relatively positive voltage (video signal) is applied to the gate electrode
14
from a gate-electrode driving circuit
31
. Depending upon an electric field generated by the application of these voltages, electrons are emitted from the top end of the electron emission electrode
16
A on the basis of a quantum tunnel effect. The electron emission device shall not be limited to the above Spindt-type field emission device, and field emission devices of other types such as edge-type, flat-type, etc., are used in some cases.
The second panel
20
comprises a plurality of phosphor layers
22
(phosphor layers
22
R,
22
G and
22
B) formed on a substrate
21
made, for example, of glass, the phosphor layers
22
having the form of a matrix or a stripe, a black matrix
23
filled between one phosphor layer
22
and another phosphor layer
22
, and an anode electrode
24
formed on the entire surface of the phosphor layers
22
and the black matrix
23
. A positive voltage higher than the positive voltage applied to the gate electrode
14
is applied to the anode electrode
24
from an anode-electrode driving circuit
37
, and the anode electrode
24
works to guide electrons emitted to the vacuum space from the electron emission electrode
16
A toward the phosphor layer
22
. Further, the anode electrode
24
also works to protect the phosphor particles constituting the phosphor layer
22
from sputtering by particles such as ions and works to reflect light emitted by the phosphor layers
22
on the basis of electron excitation to the side of the substrate
21
to improve the brightness of a display screen observed from an outside of the substrate
21
. The anode electrode
24
is made, for example, of a thin aluminum film.
Generally, the cathode electrode
12
and the gate electrode
14
are formed in the form of a stripe each in directions in which the projection images of these two electrodes
12
and
14
cross each other at right angles, and generally, a plurality of the field emission devices are arranged in an overlap region of the projection images of these two electrodes
12
and
14
(the overlap region corresponding to a region for one pixel in a monochromatic display or a region for one sub-pixel of three sub-pixels constituting one pixel in a color display). Further, such overlap regions are arranged in an effective field (region which works as an actual display screen) of the first panel
10
in the form of a two-dimensional matrix. Each pixel is constituted of a group of a predetermined number of the field emission devices arranged in the overlap region of the cathode electrode
12
and the gate electrode
14
on the first panel side and the phosphor layer
22
which is on the second panel side and faces the group of these field emission devices. The above pixels are arranged in the effective field, for example, on the order of several hundred thousands to several millions.
The first panel
10
and the second panel
20
are approximately 0.1 mm to 1 mm apart from each other. A high voltage (for example, 5 kV) is applied to the anode electrode
24
of the second panel
20
. In this display, discharges sometimes take place between the gate electrode
14
formed in the first panel
10
and the anode electrode
24
formed in the second panel
20
and may impair the quality of displayed images to a great extent. The occurrence of discharges in the vacuum is considered to have the following mechanism. First, electrons or ions emitted from the electron emission electrode
16
A under an intense electric field work as a trigger, the temperature of the anode electrode
24
locally increases due to the supply of energy to the anode electrode
24
from the anode-electrode driving circuit
37
, an occluded gas inside the anode electrode
24
is released or a material constituting the anode electrode
24
is evaporated, and such releasing or evaporation grows to be large-scale discharges (for example, spark discharges).
For displaying an image on the display, a positive voltage V
G-SL
(for example, 160 volts) is applied to a gate electrode (to be referred to as “selected gate electrode” hereinafter) constituting a pixel that is to emit lit. On the other hand, a voltage V
G-NSL
(for example, 0 volt) is applied to a gate electrode (to be referred to as “non-selected gate electrode” hereinafter) constituting a pixel that is not to emit light. Further, a voltage V
C-SL
(for example, a voltage of at least 0 volt but less than 30 volts depending upon brightness) is applied to a cathode electrode (to be referred to as “selected cathode electrode” hereinafter) constituting the pixel that is to emit light. On the other hand, a voltage V
C-NSL
(for example, 30 volts) is applied to a cathode electrode (to be referred to as “non-selected cathode electrode” hereinafter) constituting the pixel that is not to emit light. Therefore, in a pixel that emits light in the highest brightness, there is a voltage difference of 160 volts between the cathode electrode
12
and the anode electrode
14
, and in a darkest pixel, there is a voltage difference of 130 volts between the cathode electrode
12
and the gate electrode
14
.
FIG. 84A
schematically shows the above state. A voltage to be applied to the gate electrode
14
is shown as “V
g
”, and a voltage to be applied to the cathode electrode
12
is shown as “V
C
”. The voltage in the anode electrode
24
is maintained at 5 kV.
FIG. 85A
shows potentials of the selected gate electrode and the selected cathode electrode in the above state. In
FIGS. 85A
,
85
B and
86
, a blank triangle shows one example of potential of a cathode electrode, a blank circle, a solid circle and a b
Iida Koichi
Konishi Morikazu
A Minh D
Kananen, Esq. Ronald P.
Philogene Haissa
Radar Fishman & Grauer PLLC
Sony Corporation
LandOfFree
Flat-type display does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Flat-type display, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Flat-type display will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3117211