Electric lamp or space discharge component or device manufacturi – Process – With start up – flashing or aging
Reexamination Certificate
2001-09-18
2003-09-30
Luebke, Renee (Department: 2879)
Electric lamp or space discharge component or device manufacturi
Process
With start up, flashing or aging
Reexamination Certificate
active
06626718
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an apparatus for manufacturing an electron source, a method for manufacturing an electron source, and a method for manufacturing an image-forming apparatus. More particularly, the invention concerns a planar image-forming apparatus.
2. Description of the Related Art
The operation of a surface conduction electron-emitting element is based on a phenomenon wherein electron emission occurs when a current flows through a thin, small film formed on a substrate, parallel with the film surface. The present applicant has made many suggestions regarding surface conduction electron-emitting elements having novel structures, and the applications thereof. The basic structure and manufacturing methods of surface conduction electron-emitting elements are disclosed, for example, in Japanese Patent Laid-Open Nos. 7-235255 and 8-171849.
A typical surface conduction electron-emitting element includes a pair of element electrodes opposed to each other on a substrate, and a conductive thin film which is connected to the pair of element electrodes and which is provided with an electron-emitting section. A crack is made in a part of the conductive thin film. A film containing at least one of carbon and a carbon compound as a principal constituent is formed at the edge of the crack.
By placing a plurality of such electron-emitting elements on a substrate and by joining the individual electron-emitting elements by wiring, an electron source provided with a plurality of surface conduction electron-emitting elements is manufactured. By combining the electron source and a phosphor layer, a display panel of an image-forming apparatuses manufactured.
Examples of conventional methods for manufacturing such a panel using the electron source will be described below.
In a first manufacturing method, first, an electron source substrate is fabricated, in which a plurality of elements formed on a substrate is joined by wiring, each element including a conductive film and a pair of element electrodes connected to the conductive film. The entire electron source substrate is placed in a vacuum chamber. After the vacuum chamber is evacuated, a crack is formed in the conductive film of each element using an external terminal. A gas containing an organic substance is introduced into the vacuum chamber, and a voltage is applied again through the external terminal to each element in an atmosphere containing the organic substance so that carbon or a carbon compound is deposited in the vicinity of the crack.
In a second manufacturing method, first, an electron source substrate is fabricated in which a plurality of elements formed on a substrate is joined by wiring, each element including a conductive film and a pair of element electrodes connected to the conductive film. Next, the electron source substrate and a substrate provided with a phosphor layer are joined to each other with a supporting frame therebetween to produce a panel of an image-forming apparatus. Next, a voltage is applied to the conductive film of each element through an external terminal to form a crack in the conductive film. A gas containing an organic substance is introduced into the panel space via an exhaust pipe of the panel and a voltage is applied again through the external terminal to each element in an atmosphere containing the organic substance so that carbon or a carbon compound is deposited in the vicinity of the crack.
In the first manufacturing method described above, in particular, as the size of the electron source substrate increases, a larger vacuum chamber and a high vacuum exhauster are required. In the second manufacturing method, it takes a long time to evacuate the panel space of the image-forming apparatus and to introduce the gas containing the organic substance into the panel space.
Moreover, in the manufacturing methods described above, an activation gas is consumed in the activation process in order to deposit the carbon or the carbon compound on the conductive films including electron-emitting sections Therefore, when the relationship between the consumption of the activation gas during activation and the flow of the activation gas in the panel or chamber is inappropriate, the activation gas partial pressure in the panel decreases over time during the activation process. If the pressure of the activation gas changes in the activation process, the characteristics of the electron-emitting elements after activation become irregular. Specifically, since the activation rate and the electron emission efficiency depend on the pressure of the activation gas, the luminance of the panel is irregular.
FIG. 13
is a graph illustrating the relationship between the activation gas partial pressure and the electron emission efficiency. The activation gas partial pressure in the horizontal axis is shown on a logarithmic scale. The measurements performed by the present inventors show that, if the activation gas partial pressure becomes 0.8 times the original partial pressure, the electron emission efficiency becomes 1.1 times the original efficiency. Therefore, the electron emission efficiency varies depending on the sequence of activation. As a result, variations in luminance exceed several percent, and the product does not exhibit satisfactory performance.
On the other hand, if the flow of the activation gas is too large, the range of partial pressure distribution in the vacuum chamber increases and the difference between the partial pressure in the vicinity of the gas inlet and the partial pressure in the vicinity of the gas outlet increases, resulting in irregular luminance, the same problem encountered when the activation gas partial pressure changes over time.
SUMMARY OF THE INVENTION
The objects of the present invention are to provide an apparatus for manufacturing an electron source having a superior electron emission characteristic and luminance uniformity at an improved manufacturing rate, with improved mass productivity, to provide a method for manufacturing the electron source, and to provide an image-forming apparatus using the electron source.
In one aspect of the present invention, in a method for manufacturing an electron source including an electron-emitting element having a first electrode, a second electrode, and a carbon film disposed between the first electrode and the second electrode, the-electron-emitting element being placed on a front surface of a substrate, the method includes the steps of covering a partial front surface or the entire front surface of the substrate provided with the first electrode and the second electrode by a container; introducing a gas composed of a carbon compound into the container via a gas inlet of the container; and forming the carbon film by applying a voltage between the first electrode and the second electrode, wherein the relationship 1/(4/C
x
−1/C
z
)≧S
out
≧4S
act
−C
in
is satisfied, where C
in
is the conductance from the gas inlet to the position of the substrate nearest to the gas inlet, C
x
is the conductance from the position of the substrate nearest to the gas inlet to the position of the substrate nearest to a gas outlet for evacuating the container, S
out
is the effective exhaust rate of an exhaust unit connected to the gas outlet, S
act
is the consumption rate of the gas consumed by applying the voltage to the electron-emitting element, and C
z
is the conductance from the substrate to the gas outlet.
In the method for manufacturing the electron source, preferably, the electron source includes a plurality of electron-emitting elements, and the relationship 1/(4/C
x
−1/C
z
)≧S
out
≧4·n·S
act1
−C
in
is satisfied, where S
act1
is the consumption rate of the gas for each element, and n is the number of elements simultaneously subjected to the step of forming the carbon film.
In the method for manufacturing the electron source, preferably, the electron source includes a plurality of electron-emitting elements, a plurality of X-direction lines for common
Figueroa Felix O.
Luebke Renee
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