Electric lamp or space discharge component or device manufacturi – Process – With testing or adjusting
Reexamination Certificate
2000-02-23
2002-06-25
Ramsey, Kenneth J. (Department: 2879)
Electric lamp or space discharge component or device manufacturi
Process
With testing or adjusting
C445S006000, C445S024000
Reexamination Certificate
active
06409563
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an electron-emitting device manufacturing method and apparatus, driving method, and adjusting method thereof.
BACKGROUND OF THE INVENTION
Conventionally, electron-emitting devices are mainly classified into two types of devices: thermionic and cold cathode electron-emitting devices. Known examples of the cold cathode electron-emitting devices are field emission type electron-emitting devices (to be referred to as FE type electron-emitting devices hereinafter), metal/insulator/metal type electron-emitting devices (to be referred to as MIM type electron-emitting devices hereinafter), and surface-conduction type of electron-emitting devices (to be referred to as SCE type electron-emitting devices hereinafter.
Known examples of the FE type electron-emitting devices are disclosed 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).
A known example of the MIM type electron-emitting devices is disclosed in C. A. Mead, “Operation of Tunnel-Emission Devices”, J. Appl. Phys., 32,646 (1961).
A known example of the SCE type electron-emitting devices is disclosed in, e.g., M. I. Elinson, Radio Eng. Electron Phys., 10, 1290 (1965).
The SCE type 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 SCE type electron-emitting device includes electron-emitting devices using an SnO
2
thin film according to Elinson mentioned above [M. I. Elinson, Radio Eng. Electron Phys., 10, 1290, (1965)], 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.
The FE, MIM, and SCE type electron-emitting devices have an advantage that many devices can be arranged on a substrate. Various image display apparatuses using these devices have been proposed.
It is known that characteristic changes in actual driving can be suppressed by applying a voltage higher than a voltage applied in the actual driving in the manufacturing process of the SCE type electron-emitting device.
An image display apparatus formed using the electron-emitting devices must maintain brightness and contrast suitable for image display over a long term.
To realize this, the electron-emitting device must emit a predetermined electron amount or more in an expected term, while suppressing a decrease in electron amount emitted by the electron-emitting device.
However, the conventional electron-emitting device gradually decreases the electron emission amount along with long-term driving at a constant driving voltage.
In any type of electron-emitting device described above, the field strength near the electron-emitting portion is high during the actual driving. Changes over time near the electron-emitting portion arising from a high field strength is considered to decrease the electron emission amount.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an electron-emitting device manufacturing method and driving method capable of suppressing changes over time in characteristics of an electron-emitting device and, more particularly, to provide an electron-emitting device manufacturing method and driving method capable of suppressing a decrease over time and unstableness in the electron emission amount from the electron-emitting device.
An electron-emitting device manufacturing method according to the present invention has the following steps.
That is, there is provided a method of manufacturing an electron-emitting device which has at least two electrodes and emits electrons by applying a voltage between the two electrodes, comprising:
the voltage application step of applying a voltage V
1
between the two electrodes, the voltage V
1
being a voltage having a relationship with a maximum voltage value V
2
applied to the electron-emitting device as a normal driving voltage after the voltage application step, so as to satisfy
giving a current I flowing upon application of a voltage V when the voltage V falling within a voltage range causing electron emission upon application of the voltage between the two electrodes is applied between the two electrodes:
I=f
(
V
) (1)
and letting f′(V) be a differential coefficient of f(V) at the voltage V,
a first condition:
f
(
V
1
)
/{V
1
·f′
(
V
1
)−2
f
(
V
1
)}
>f
(
V
2
)
/{V
2
·f′
(
V
2
)−2
f
(
V
2
)} (2)
wherein the voltage application step satisfies a second condition, upon completion of the voltage application step,
wherein the second condition is defined by letting Xn-
1
be a value of a right side, i.e., f(V
2
)/{V
2
·f′(V
2
)−2f(V
2
)} of the inequality (2) upon a first application of the pulse-like voltage V
2
when the voltage V
2
is applied as pulses successively twice between the two electrodes upon completion of the voltage application step, and Xn be a value of the right side, i.e., f(V
2
)/{V
2
·f′(V
2
)−2f(V
2
)} of the inequality (2) upon a second application of the pulse-like voltage V
2
,
wherein Xn-
1
and Xn satisfy:
(
Xn
-
1
−Xn
)
/Xn
-
1
≦0.02 (A)
The second condition is that Xn-
1
and Xn satisfy:
(
Xn
-
1
−Xn
)
/Xn
-
1
≦0.01 (B)
The electron-emitting device manufactured through the voltage application step hardly changes its characteristics upon long-time application of the maximum voltage value V
2
applied in actually driving the electron-emitting device (normally using it). The current I flowing upon application of the voltage V when the voltage V falling within a voltage range causing electron emission upon application of the voltage between the two electrodes is applied between the two electrodes is a current emitted upon application of the voltage V or a current flowing between the two electrodes. For example, in an FE or SCE type electron-emitting device, the current I is an emitted current or a current flowing between a pair of electrodes.
In an MIM type electron-emitting device, the current I is an emitted current or a current (diode current) flowing between two electrodes sandwiching an insulating layer. The differential coefficient f′(Vn) of f(Vn) at a given voltage Vn can be obtained as follows. An emission current (or a current flowing between two electrodes) In upon application of the voltage Vn, and an emission current (or a current flowing between the two electrodes) In
2
upon application of a voltage Vn
2
lower by a small amount dVn than the voltage Vn immediately after or immediately before application of the voltage Vn are obtained, and (In−In
2
) is divided by dVn. That is, f(V)/{V·f′(V)−2f(V)} can be calculated as In/{Vn·(In−In
2
)/dVn−2In}.
Especially, the second condition is more preferably a condition that the change rate of Xn, i.e., (Xn-
1
−Xn)/Xn-
1
is 1% or less.
The voltage V
1
can be applied by various methods. The magnitude of the voltage V
1
is not necessarily constant as long as the voltage V
1
satisfies the condition of the inequality (2). The voltage V
1
is preferably applied as a pulse-like voltage.
To satisfy the second condition by the voltage application step, a voltage is applied under the same conditions as those adopted in applying the present invention, between two electrodes identical to two electrodes constituting at least part of an electron-emitting device to which the present invention is applied. Xn-
1
and Xn are measured for the electron-emitting device obtained in this step, thereby attaining conditions under which Xn-
1
and Xn satisfy the inequality (A), and more preferably the inequality (B). For example,
Hamamoto Yasuhiro
Tamura Miki
Yamamoto Keisuke
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