Electric lamp and discharge devices – With luminescent solid or liquid material – Vacuum-type tube
Reexamination Certificate
1998-04-23
2001-09-11
Patel, Nimeshkumar D. (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
Vacuum-type tube
C313S496000, C313S497000
Reexamination Certificate
active
06288485
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electron apparatus associated with electron emission and, more particularly, to an image forming apparatus for forming an image by electrons.
2. Description of the Related Art
Conventionally, two types of devices, namely hot and cold cathode devices, are known as electron-emitting devices. Known examples of the cold cathode devices are surface-conduction emission (SCE) type electron-emitting devices, field emission type electron-emitting devices (to be referred to as FE type electron-emitting devices hereinafter), and metal/insulator/metal type electron-emitting devices (to be referred to as MIM type electron-emitting devices hereinafter).
A known example of the surface-conduction emission type electron-emitting devices is described in, e.g., M. I. Elinson, “Radio Eng. Electron Phys., 10, 1290 (1965) and other examples will be described later.
The surface-conduction emission type electron-emitting device utilizes the phenomenon that electrons are emitted from a small-area thin film formed on a substrate by flowing a current parallel through the film surface. The surface-conduction emission type electron-emitting device includes electron-emitting devices 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. 17
is a plan view showing the device proposed by M. Hartwell et al. described above as a typical example of the device structures of these surface-conduction emission type electron-emitting devices. Referring to
FIG. 17
, numeral
3001
denotes a substrate; and
3004
, a conductive thin film made of a metal oxide formed by sputtering. This conductive thin film
3004
has an H-shaped pattern, as shown in FIG.
17
. An electron-emitting portion
3005
is formed by performing electrification processing (referred to as forming processing to be described later) with respect to the conductive thin film
3004
. An interval L in
FIG. 17
is set to 0.5 to 1 mm, and a width W is set to 0.1 mm. The electron-emitting portion
3005
is shown in a rectangular shape at the center of the conductive thin film
3004
for the sake of illustrative convenience. However, this does not exactly show the actual position and shape of the electron-emitting portion
3005
.
In the above surface-conduction emission type electron-emitting devices by M. Hartwell et al. and the like, typically the electron-emitting portion
3005
is formed by performing electrification processing called forming processing for the conductive thin film
3004
before electron emission. That is, the forming processing is to form an electron-emitting portion by electrification. For example, a constant DC voltage or a DC voltage which increases at a very low rate of, e.g., 1 V/min is applied across the two ends of the conductive thin film
3004
to partially destroy or deform the conductive thin film
3004
, thereby forming the electron-emitting portion
3005
with an electrically high resistance. 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 forming processing, electrons are emitted near the fissure.
Known examples of the FE type electron-emitting devices 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 molybdenium cones”, J. Appl. Phys., 47, 5248 (1976).
FIG. 18
is a cross-sectional view showing the device proposed by C. A. Spindt et al. described above as a typical example of the FE type device structure. Referring to
FIG. 18
, 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 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
. As another FE type device structure, there is an example in which an emitter and a gate electrode are arranged on a substrate to be almost parallel to the surface of the substrate, in addition to the multilayered structure of FIG.
18
.
A known example of the MIM type electron-emitting devices is described in C. A. Mead, “Operation of Tunnel-Emission Devices”, J. Appl. Phys., 32,646 (1961).
FIG. 19
shows a typical example of the MIM type device structure.
FIG. 19
is a cross-sectional view of the MIM type electron-emitting device. Numeral
3020
denotes a substrate;
3021
, a lower electrode made of a metal;
3022
, a thin insulating layer having a thickness of about 100 A; and
3023
, an upper electrode made of a metal and having a thickness of about 80 to 300 A. In the MIM type electron-emitting device, an appropriate voltage is applied between the upper electrode
3023
and the lower electrode
3021
to emit electrons from the surface of the upper electrode
3023
.
Since the above-described cold cathode devices can emit electrons at a temperature lower than that for hot cathode devices, they do not require any heater. The cold cathode device therefore has a structure simpler than that of the hot cathode device and can be micropatterned. Even if a large number of devices are arranged on a substrate at a high density, problems such as heat fusion of the substrate hardly arise. In addition, the response speed of the cold cathode device is high, while the response speed of the hot cathode device is low because it operates upon heating by a heater. For this reason, applications of the cold cathode devices have enthusiastically been studied.
Of cold cathode devices, the above surface-conduction emission type electron-emitting devices 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 emission type electron-emitting devices to, e.g., image forming apparatuses such as an image display apparatus and an image recording apparatus, electron-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 Nos. 2-257551 and 4-28137 filed by the present applicant, an image display apparatus using the combination of an surface-conduction emission type electron-emitting device and a fluorescent substance which emits light upon reception of an electron beam has been studied. This type of image display apparatus using the combination of the surface-conduction emission type electron-emitting device and the fluorescent substance is expected to have more excellent characteristics 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 because it is of a self-emission type and that it has a wide view angle.
A method of driving a plurality of FE type electron-emitting devices arranged side by side is disclosed in, e.g., U.S. Pat. No. 4,904,895 filed by the present applicant. As a known example of an application of FE type electron-emitting devices to an image display apparatus is a flat display apparatus reported by R. Meyer et al. [R. Meyer: “Recent Development on Microtips Display at LETI”, Tech. Digest of 4th Int. Vacuum Microelectronics Conf., Nagahama, pp. 6-9 (1991)].
An example of an application of a larger number of MIM
Mitsutake Hideaki
Takegami Tsuyoshi
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Patel Nimeshkumar D.
Santiago Mariceli
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