Electric lamp and discharge devices – Discharge devices having a multipointed or serrated edge...
Reexamination Certificate
2000-09-25
2003-10-21
Patel, Ashok (Department: 2879)
Electric lamp and discharge devices
Discharge devices having a multipointed or serrated edge...
C313S336000, C313S310000, C313S495000
Reexamination Certificate
active
06635979
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an electron emitting device for emitting electrons using an appropriate material (for example, diamond particles) as an electron emitting source (emitter), a method for producing the same, and an image display apparatus including such an electron emitting device, and a method for producing such an image display apparatus. The present invention also relates to a method for driving the electron emitting device.
BACKGROUND ART
Recently, microscopic electron emitting devices have actively been developed as electron emitting sources for thin display devices and as emitters of microscopic vacuum devices capable of a high-speed operation. Conventionally used electron emitting devices are of a “heat releasing type”, which applies a high voltage to a material, such as tungsten, heated to a high temperature. Recently, research and development of “cold cathode type” electron emitting devices which do not need to be heated to a high temperature and thus can emit electrons even at a low voltage have actively been performed.
Cold cathode type electron emitting devices (hereinafter, also referred to as “cold cathode devices”) are required to be driven at a low voltage and a low power consumption and to stably obtain a large amount of current. As such a cold cathode type electron emitting device, a device using diamond for an electron emitting region (emitter) has recently been proposed. Such a device has been proposed utilizing the facts that diamond is a semiconductor material having a wide forbidden band (5.5 eV); has very suitable characteristics for a material for an electron emitting device such as, for example, a high hardness, a high resistance against wearing, a high heat conductivity, and chemical inactivity; and can obtain a negative electron affinity by controlling a surface state to make the energy level of the end of the conduction band lower than the energy level of the vacuum area. Especially, the characteristic of the negative electron affinity means that electrons can easily be emitted by injecting electrons into the conduction band of diamond.
An electron emitting device using diamond is disclosed in, for example, Japanese Laid-Open Publication No. 7-282715. A structure disclosed in the publication is shown as simplified in FIG. 29.
Specifically in the structure shown in FIG. 29, a conductive layer 1112 acting as an electrode is formed on a substrate 1111, and an electron emitting region 1114 formed of diamond particles 1113 is formed on the conductive layer 1112. Each of the diamond particles 1113 has a negative electron affinity as a result of a prescribed treatment. A counter electrode (not shown) is provided so as to face the electron emitting region 1114 formed of the diamond particles 1113. Electrons are emitted from each diamond particle 1113 by supplying the counter electrode with a potential.
In the conventional structure shown in FIG. 29, the electron affinity of a surface of the diamond particles 1113 is negative. Accordingly, the electrons migrating into the diamond particles 1113 from the conductive layer 1112 should be easily emitted from the diamond particles 1113. Therefore, theoretically, electrons can be emitted from the diamond particles 1113 without application of a high voltage to the counter electrode (not shown).
However, in actuality, a high voltage as in a previous structure needs to be applied to the counter electrode in order to cause electrons to emit with the structure shown in FIG. 29.
DISCLOSURE OF THE INVENTION
The present invention made in light of the above-described problem of the conventional art has objectives of providing (1) an electron emitting device capable of stably providing a large amount of current when driven at a low voltage and a method for producing the same, (2) an image display apparatus including such an electron emitting device and a method for producing the same, and (3) a method for driving such an electron emitting device.
An electron emitting device according to the present invention includes at least comprising an electron transporting member; an electron emitting member; and an electric field concentration region formed between the electron transporting member and the electron emitting member.
The electron transporting member may be a conductive layer.
The electric field concentration region may be formed of an insulating layer.
The electron emitting member may be formed of particles.
In one embodiment, the electron transporting member is a conductive layer, the electric field concentration region is formed of an insulating layer formed on the conductive layer, and the electron emitting member is formed of particles provided on the insulating layer.
In one embodiment, the electron emitting device further includes an extraction electrode provided at a prescribed position with respect to the electron emitting member and supplied with a potential for extracting electrons from the electron emitting member.
In one embodiment, a surface of the electron transporting member is roughened so as to have convex and concave portions, and the electron emitting member is provided on the roughened surface of the electron transporting member, with at least the convex portions of the convex and concave portions interposed therebetween.
In one embodiment, the electron emitting device further includes a circuit for causing an electric current to flow in the electron transporting member.
In one embodiment, the electric field concentration region is formed of an insulating layer formed on a surface of the particles forming the electron emitting member, and the particles are provided on the electron transporting member with the insulating layer interposed therebetween.
In another embodiment, the electron transporting member is a conductive layer, and the electric field concentration region is formed of an insulating layer formed on the conductive layer, and the electron emitting member is formed of particles provided so as to be partially buried in the insulating layer.
Preferably, the electric field concentration region has a thickness of 1000 Åor less.
In one embodiment, the electron emitting member is formed of a plurality of particles provided independently, out of contact with one another.
Preferably, the electron emitting member in formed of particles of a material having a negative electron affinity.
The particles may be diamond particles. For example, the diamond particles are artificial diamond particles. Alternatively, the diamond particles are diamond particles synthesized by a vapor phase technique.
Alternatively, the particles are carbon particles partially having a diamond structure.
An outermost surface layer of the diamond particles may have a termination structure bonded with hydrogen.
For example, the diamond particles are formed by being exposed to a hydrogen atmosphere of 600° C. or higher.
The diamond particles may include an impurity.
The impurity may be formed by ion implantation. Preferably, the impurity has a density of 1×10
13
/cm
3
or higher.
The electron transporting member may be a conductive layer formed of a material having a small work function.
An electron emitting device according to another aspect of the invention includes at least comprising an electron injection member; an electron emitting member; and an electron transporting member formed between the electron transporting member and the electron emitting member. The electron transporting member includes an electrically insulating or highly resistive portion when supplied with a prescribed low DC voltage.
Preferably, the electron transporting member includes a portion having an electric resistance of 1 k&OHgr;cm or higher when supplied with such a weak electric field as to make a highest electric field strength in the electron transporting member 1 mV/&mgr;m or less.
The electron emitting member may include a substance having a negative electron affinity.
The electron emitting member may include a substance containing at least carbon or particles thereof. For example, the electron emittin
Deguchi Masahiro
Kitabatake Makoto
Kurokawa Hideo
Shiratori Tetsuya
Matsushita Electric - Industrial Co., Ltd.
Patel Ashok
RatnerPrestia
Zimmerman Glenn
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