Electric lamp and discharge devices – With luminescent solid or liquid material – Vacuum-type tube
Reexamination Certificate
2002-10-04
2004-03-02
Patel, Vip (Department: 2879)
Electric lamp and discharge devices
With luminescent solid or liquid material
Vacuum-type tube
C313S292000, C313S422000, C313S258000, C445S024000
Reexamination Certificate
active
06700321
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image forming apparatus having a multi-electron source and fluorescent substances, and method of manufacturing the image forming apparatus.
2. Description of the Related Art
Flat display apparatuses are thin and lightweight. Attention is therefore being given to them as apparatuses replacing CRT type display apparatuses. A display apparatus using a combination of an electron-emitting device and a fluorescent substance which emits light upon reception of an electron beam, in particular, is expected to have better characteristics than display apparatuses based on other conventional schemes. 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.
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 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 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 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. 15
is a plan view showing the device by M. Hartwell et al. described above as a typical example of the device structures of these surface-conduction emission type emitting devices. Referring to
FIG. 15
, reference 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.
15
. 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. 15
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.
In the above surface-conduction emission type 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. In the forming processing, 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 molybdenum cones”, J. Appl. Phys., 47, 5248 (1976).
FIG. 16
is a sectional view showing the device by C. A. Spindt et al. described above as a typical example of the FE type device structure. Referring to
FIG. 16
, reference numeral
3010
denotes a substrate;
3011
, emitter wiring 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 multi-layered structure of FIG.
16
.
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. 17
shows a typical example of the MIM type device structure.
FIG. 17
is a sectional view of the MIM type electron-emitting device. Referring to
FIG. 17
, 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 angstrom; and
3023
, an upper electrode made of a metal and having a thickness of about 80 to 300 angstrom. 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 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 emitting devices to, e.g., image forming apparatuses such as an image display apparatus and an image recording apparatus, a multi-electron source, 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 a surface-conduction emission type 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 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 metho
Fushimi Masahiro
Kuroda Kazuo
Mitsutake Hideaki
Ohguri Noriaki
Ohsato Yoichi
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Patel Vip
Williams Joseph
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