Computer graphics processing and selective visual display system – Plural physical display element control system – Display elements arranged in matrix
Reexamination Certificate
1996-08-13
2002-01-15
Luu, Matthew (Department: 2672)
Computer graphics processing and selective visual display system
Plural physical display element control system
Display elements arranged in matrix
Reexamination Certificate
active
06339414
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an electron generating apparatus, an image display apparatus, a driving circuit, and a driving method and, more particularly, to an image display apparatus having a large number of surface-conduction type electron emitters.
Conventionally, two types of devices, namely thermionic and cold cathode devices, are known as electron emitters. Examples of cold cathode devices are field emission type electron emitters (to be referred to as field emitters hereinafter), metal/insulator/metal type electron emitters (to-be referred to as MIM-type electron emitters hereinafter), and surface-conduction type electron emitters.
Known examples of the field emitters are described in W. P. Dyke and W. W. Dolan, “Field Emission”, Advance in Electron Physics, 8, 89 (1956) and C.A. Spindt, “Physical Properties of thin-film field emission cathodes with molybdenum cones”, J. Appl. Phys., 47, 5248 (1976).
FIG. 38
is a sectional view of a device according to C.A. Spindt et al. Referring to
FIG. 38
, reference numeral
3010
denotes a substrate,
3011
, an emitter wiring layer made of a conductive material;
3012
, an emitter cone;
3013
, an insulating layer; and
3014
, a gate electrode. In this device, a proper voltage is applied between the emitter cone
3012
and the gate electrode
3014
to emit electrons from the distal end portion of the emitter cone
3012
.
A known example of the MIM-type electron emitters is described in C. A. Mead, “Operation of Tunnel-Emission Devices”, J. Appl. Phys., 32, 646 (1961).
FIG. 39
is a sectional view of an MIM-type electron emitter. Referring to
FIG. 39
, reference numeral
3020
denotes a substrate;
3021
, a lower electrode made of a metal;
3022
, a thin insulating layer having a thickness of about 100 Å; and
3023
, an upper electrode made of a metal and having a thickness of about 80 to 300 Å. In the MIM type, a voltage is applied between the upper electrode
3023
and the lower electrode
3021
to emit electrons from the surface of the upper electrode
3023
.
A known example of the surface-conduction type electron emitters is described in, e.g., M. I. Elinson, “Radio Eng. Electron Phys., 10, 1290 (1965) and other examples to be described later.
The surface-conduction type electron emitter utilizes the phenomenon that electron emission takes place in a small-area thin film, formed on a substrate, upon flowing a current parallel to the film surface. The surface-conduction type electron emitter includes electron emitters using an Au thin film (G. Dittmer, “Thin Solid Films”, 9, 317 (1972)), an In
2
O
3
/SnO
2
thin film (M. Hartwell and C. G. Fonstad, “IEEE Trans. ED Conf.”, 519 (1975)), a carbon thin film (Hisashi Araki et al., “Vacuum”, vol. 26, No. 1, p. 22 (1983), and the like, in addition to an SnO
2
thin film according to Elinson mentioned above.
FIG. 37
is a plan view of the surface-conduction type electron emitter according to M. Hartwell et al. as a typical example of the structures of these surface-conduction type electron emitters. Referring to
FIG. 37
, reference numeral
3001
denotes a substrate; and
3004
, a conductive thin film made of a metal oxide formed by spattering. This conductive thin film
3004
has an H-shaped pattern, as shown in FIG.
37
. An electron-emitting portion
3005
is formed by performing an energization process (referred to as a energization forming process to be described later) with respect to the conductive thin film
3004
. Referring to
FIG. 37
, an interval L is set to 0.5 to 1 mm, and a width W is set to 0.1 mm. For the sake of illustrative convenience, the electron-emitting portion
3005
is shown in a rectangular shape at the center of the conductive thin film
3004
. However, this does not exactly show the actual position and shape of the electron-emitting portion.
In the above surface-conduction type electron emitters according to M. Hartwell et al., typically the electron-emitting portion
3005
is formed by performing an energization process called the energization forming process for the conductive thin film
3004
before electron emission. According to the energization forming process, energization is performed by applying a constant DC voltage which increases at a very low rate of, e.g., 1 V/min., across the two ends of the conductive film
3004
, so as to partially destroy or deform the conductive film
3004
, thereby forming the electron-emitting portion
3005
with an electrically high resistor. Note that the destroyed or deformed part of the conductive thin film
3004
has a fissure. Upon application of an appropriate voltage to the conductive thin film
3004
after the energization forming process, electron emission is performed near the fissure.
The above surface-conduction type electron emitters are advantageous because they have a simple structure and can be easily manufactured. For this reason, many devices can be formed on a wide area. As disclosed in Japanese Patent Laid-Open No. 64-31332 filed by the present applicant, a method of arranging and driving a lot of devices has been studied.
Regarding applications of surface-conduction type electron emitters to, e.g., image forming apparatuses such as an image display apparatus and an image recording apparatus, charged beam sources and the like have been studied.
As an application to image display apparatuses, in particular, as disclosed in the U.S. Pat. No. 5,066,883 and Japanese Patent Laid-Open No. 2-257551 filed by the present applicant, an image display apparatus using the combination of a surface-conduction type electron emitter and a phosphor which emits light upon irradiation of an electron beam has been studied. This type of image display apparatus is expected to have more excellent characteristic than other conventional image display apparatuses. For example, in comparison with recent popular liquid crystal display apparatuses, the above display apparatus is superior in that it does not require a backlight since it is of a self-emission type and that it has a wide view angle.
The present inventors have experimented on surface-conduction type electron emitters made of various materials, manufactured by various methods, and having various structures as well as the one described above. The present inventors have also studied multi-electron sources each constituted by an array of many surface-conduction type electron emitters, and image display apparatuses using the multi-electron sources.
The present inventors have experimentally manufactured a multi-electron source formed by an electrical wiring method like the one shown in FIG.
40
. In this multi-electron source, a large number of surface-conduction type electron emitters are two-dimensionally arrayed and wired in the form of a matrix, as shown in FIG.
40
.
Referring to
FIG. 40
, reference numeral
1002
denotes a surface-conduction type electron emitter which is schematically shown;
1003
, a row wiring layer; and
1004
, a column wiring layer. In reality, the row and column wiring layers
1003
and
1004
have finite electric resistors. However,
FIG. 40
shows these resistors as wiring resistors
4004
and
4005
. The above wiring method will be referred to as simple matrix wiring.
For the sake of illustrative convenience,
FIG. 40
shows a 6×6 matrix. However, the size of a matrix is not limited to this. For example, in a multi-electron source for an image display apparatus, a sufficient number of emitters for a desired image display operation are arrayed and wired.
In the multi-electron source having the surface-conduction type electron emitters wired in the form of a simple matrix, in order to output desired electron beams, proper electrical signals are applied to the row and column wiring layers
1003
and
1004
. For example, in order to drive the surface-conduction type electron emitters on an arbitrary row in the matrix, a selection voltage Vs is applied to the row wiring layer
1003
on a selected row, and at the same time, a non-selection voltage Vns is applied to each row wiring layer
10
Suzuki Hidetoshi
Todokoro Yasuyuki
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Luu Matthew
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