Electric lamp and discharge devices: systems – Plural power supplies – Plural cathode and/or anode load device
Reexamination Certificate
2002-01-16
2003-03-25
Wong, Don (Department: 2821)
Electric lamp and discharge devices: systems
Plural power supplies
Plural cathode and/or anode load device
C315S169400, C313S495000
Reexamination Certificate
active
06538391
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an image display and a method of manufacturing the same, and particularly to a technology effective for application to a display apparatus which has thin-film electron emitters having an electrode-insulator-electrode structure to emit electrons into vacuum.
The thin-film electron emitters are electron-emitter elements each using hot electrons produced by applying a high electric field to an insulator.
As a typical example, an MIM (Metal-Insulator-Metal) electron emitter comprising a thin film having a three-layer structure of a top electrode-insulating layer-base electrode will be explained.
FIG. 14
is a diagram for describing the principle of operation of an MIM electron emitter illustrated as a typical example of a thin-film electron emitter.
A driving voltage is applied between a top electrode
11
and a base electrode
13
to set an electric field within a tunneling insulator 12 to 1 MV/cm to 10MV/cm and over. Thus, electrons placed in the neighborhood of the Fermi level in the base electrode
13
are transmitted through a barrier by tunneling phenomena. Thereafter, they are injected into the conduction bands of the tunneling insulator
12
and top electrode
11
, thereby resulting in hot electrons.
Some of these hot electrons are subjected to scattering under interaction with a solid in the tunneling insulator
12
and the top electrode
11
, thus leading to the loss of energy.
As a result, hot electrons having various energies exist when they have reached an interface between the top electrode
11
and vacuum
10
.
Of these hot electrons, ones having energy larger than the work function &phgr; of the top electrode
11
are emitted into the vacuum
10
, and ones other than the above ones flow into the top electrode
11
.
Assuming that a current based on the electrons flowing from the base electrode
13
to the top electrode
11
, is called a diode current (Id), and a current based on the electrons emitted into the vacuum
10
is called an emission current (Ie), an electron emission efficiency (Ie/Id) ranges from about 1/10
3
to about 1/10
5
.
Incidentally, the MIM thin-film electron emitter has been described in, for example, Japanese Patent Application Laid-Open No. Hei 9-320456.
Now, the top electrode
11
and the base electrode
13
are provided in plural form and these plural top electrodes
11
and base electrodes
13
are formed orthogonal to one another to thereby form thin-film electron emitters in matrix form. Consequently, electron beams can be produced from arbitrary locations and hence they can be used as electron emitters for a display apparatus.
Namely, a display apparatus can be constructed wherein thin-film electron-emitter elements are placed at every pixel, and electrons emitted therefrom are accelerated in vacuo and thereafter applied to each of phosphors to thereby allow the applied phosphor to emit light, whereby a desired image is displayed thereon.
The thin-film electron emitters have excellent features as electron-emitter elements for the display apparatus in that they are capable of implementing a high-resolution display apparatus because the emitted electron beams are excellent in directionality, and they are easy to handle because they are insusceptible to the influence of their surface contamination, for example.
In the display apparatus using the conventional thin-film electron emitters, when one of a large number of thin-film electron-emitter elements (electron emission regions) placed in matrix form was short-circuited due to a failure in manufacture thereof or other reasons, no electrons were emitted from all the thin-film electron-emitter elements on a row or/and a column to which such a thin-film electron-emitter element was connected, thus causing no light emission. Namely, a “point defect” of one thin-film electron-emitter element has caused a “line defect”.
The above-described point will be explained below.
FIG. 15
is a diagram showing a schematic configuration of a conventional thin-film electron-emitter matrix.
Thin-film electron-emitter elements
301
are respectively formed at points where row electrodes (base electrodes)
310
and column electrodes (top electrodes)
311
intersect respectively.
Incidentally, while the thin-film electron-emitter matrix is illustrated with 3 rows and 3 columns in
FIG. 15
, the thin-film electron-emitter elements
301
are actually placed by the number of pixels constituting a display apparatus, or the number of sub-pixels in the case of a color display apparatus.
Now, the respective thin-film electron-emitter elements
301
are directly connected to the row electrodes
310
and the column electrodes
311
respectively.
Therefore, when, for example, a thin-film electron-emitter element
301
placed at an intersection (R
2
, C
2
) of a row electrode
310
of R
2
and a column electrode
311
of C
2
is short-circuited due to a failure in manufacture thereof or the like, the row electrode
310
of R
2
and the column electrode
311
of C
2
are short-circuited. Hence even if an attempt were made to apply a suitable voltage to both electrodes from a row electrode driving circuit
41
or a column electrode driving circuit
42
, the voltage would not be applied thereto.
Therefore, all the thin-film electron-emitter elements
301
on the row electrode of R
2
, or/and all the thin-film electron-emitter elements
301
on the column electrode
311
of C
2
are not operated, thus causing a “line defect”.
Even if elements equivalent to about {fraction (1/10000)} of the total number of pixels have “point defects” in a matrix-type display apparatus such as a liquid-crystal display apparatus or the like, no problem occurs from a practical standpoint and they can be used in most cases.
Namely, about 100 “point defects” can be allowed in the case of a display apparatus configured in 480×640×3 dots, for example.
However, one having a “line defect” such as non-light emission of all elements on one line cannot be used as a display apparatus.
Thus, the display apparatus using the conventional thin-film electron emitters was accompanied by a problem that the “point defects”produced the “line defect”, thereby reducing production yields.
SUMMARY OF THE INVENTION
The present invention has been made to solve the problem of the prior art. An object of the present invention is to provide a technology capable of enhancing production yields in an image display.
The above, other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.
Summaries of typical one of the inventions disclosed in the present application will be described in brief as follows:
There is provided an image display which comprises a display device including a first plate which has a plurality of electron-emitter elements each having a structure comprised of a base electrode, an insulating layer and a top electrode stacked on one another in this order, the electron-emitter element emitting electrons from the surface of the top electrode when a voltage of positive polarity is applied to the top electrode; a plurality of first electrodes for respectively applying driving voltages to the base electrodes of the electron-emitter elements lying in a row (or column) direction, of the plurality of electron-emitter elements; and a plurality of second electrodes for respectively applying driving voltages to the top electrodes of the electron-emitter elements lying in the column (or row) direction, of the plurality of electron-emitter elements, a frame component, and a second plate having phosphors, whereby a space surrounded by the first plate, the frame component and the second plate is brought to vacuum, wherein at least one the electron-emitter element includes its corresponding base electrode and top electrode at least one of which is connected to the first electrode or second electrode through a resistor element.
Namely, the present invention is characterized in that a resistor is inserted bet
Kusunoki Toshiaki
Sagawa Masakazu
Suzuki Mutsumi
Alemu Ephrem
Hitachi LTD
Wong Don
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