Electron-emitting device, electron source, and image display apparatus, and method for manufacturing the same

A base body includes a first part and a second part. The second part has a lower thermal conductivity than the first part and is arranged adjacently to the first part. A first conductive film is formed on the first part and a second conductive film is formed on the second part. At least part of a gap is located above a boundary between the first part and the second part.

CROSS REFERENCE TO RELATED APPLICATIONS

This Application is a National Stage filing under 35 U.S.C. §371 of International Application No. PCT/JP2007/063528, filed Jun. 29, 2007, and claims priority to Japanese Patent Application No. 2006-202140, filed Jul. 25, 2006, each of which is incorporated by reference herein in its entirety, as if set forth fully herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electron-emitting device and an electron source using the same and an image display apparatus using the same. Moreover, the present invention relates to an information reproducing apparatus such as a television receiver that receives a broadcast signal of a television broadcast and displays and reproduces image information, character information, and voice information, which are included in the received broadcast signal.

2. Description of the Related Art

A conventional process for manufacturing a surface conduction electron-emitting device is schematically shown with reference toFIG. 17. First, a pair of auxiliary electrodes2,3are formed on a substrate1(FIG. 17A). Next, the pair of auxiliary electrodes2,3are connected to each other by a conductive film4(FIG. 17B). Then, a voltage is applied between the pair of auxiliary electrodes2,3to form a first gap7in a portion of the conductive film4(FIG. 17C). This processing is called “current passing forming”. The “current passing forming” processing is a process of passing a current through the conductive film4to form the first gap7in the portion of the conductive film4by joule heat developed by the current. A pair of electrodes4a,4bopposite to each other across the first gap7are formed by the processing of “current passing forming”. Then, the pair of electrodes4a,4bare subjected to processing called “activation”. The “activation” processing is processing such that a voltage is applied between the pair of auxiliary electrodes2,3in an atmosphere of gas containing carbon. With this processing, a conductive carbon film21a,21bcan be formed on the substrate1in the first gap7and the electrodes4a,4bnear the first gap7(FIG. 17D). An electron-emitting device is formed by the foregoing processing.

FIG. 16Ais a plan view to schematically show an electron-emitting device subjected to the foregoing “activation” processing.FIG. 16Bis a schematic cross-sectional view along a line B-B′ inFIG. 16A, which is basically equivalent toFIG. 17D. InFIG. 16AandFIG. 16B, parts denoted by the same reference numbers as shown inFIG. 17denote the same parts as shown inFIG. 17. When electrons are emitted from the electron-emitting device, an electric potential applied to one auxiliary electrode2or3is made higher than an electric potential applied to the other auxiliary electrode3or2. When the voltage is applied between the auxiliary electrode2and the auxiliary electrode3in this manner, a strong electric field is developed in a second gap8. As a result, it is thought that electrons tunnel from many points (a plurality of electron-emitting parts) in a portion that forms the end edge of the carbon film21aor21bconnected to the auxiliary electrode3or2on the lower electric potential side and forms the outer edge of the second gap8, and that at least some of the electrons are emitted.

In the below-listed patent documents 1 to 6 there is disclosed a technology for controlling the shape of the foregoing auxiliary electrodes2,3and the shape of the conductive film4to control the position of the gap.

An image display apparatus can be constructed by arranging a substrate having an electron source constructed of a plurality of electron-emitting devices of this kind opposite to a substrate having a fluorescent film formed of a fluorescent substance or the like and by keeping the interior of the two substrates in a vacuum.

SUMMARY OF THE INVENTION

In modern image display apparatuses, it is required that a displayed image be stably displayed for a long time. For this reason, in an image display apparatus having an electron source constructed of a plurality of electron-emitting devices, it is required that the respective electron-emitting devices can keep excellent characteristics for a long time.

Moreover, as described above, it is thought that electrons tunnel from many points that form a part of the end edge of one carbon film21aor21band construct the outer edge of the gap8. For example, when the electron-emitting device is driven with the electric potential of the first auxiliary electrode2made higher than the electric potential of the second auxiliary electrode3, the second carbon film21bconnected to the second auxiliary electrode3via the second electrode4bcorresponds to an emitter. As a result, it can be thought that many electron-emitting parts exist in a portion that is the end edge of the second carbon film21band forms the outer edge of the second gap8. In other words, it can be thought that many electron-emitting parts are arranged in the end edge of the carbon film21aor21bconnected to the auxiliary electrode3or2having the lower electric potential applied thereto. For this reason, the electron-emitting parts, which are arranged at the edge of the carbon film21aor21bconnected to the auxiliary electrode3or2having a lower electric potential applied thereto, have current passed therethrough, thereby being brought into high temperature. When the electron-emitting parts are brought into excessively high temperature, the carbon film gradually disappears. As a result, it can be thought that there are cases where these electron-emitting devices may deteriorate in the quantity of emission of the electrons over time. On the other hand, it can be thought that there are cases where carbon film21aor21bconnected to the auxiliary electrode3or2having the higher electric potential applied thereto may adsorb gas or the like remaining in the atmosphere and, as a result, may vary in the electron emission characteristics.

For these reasons, in the electron source constructed of many electron-emitting devices, there are cases where there is deterioration in the quantity of emission of the electrons and variations in the electron emission characteristics, which can be thought to be caused by the disappearance of the carbon film and by the adsorption of the remaining gas. Moreover, in the image display apparatus using the electron-emitting device, there are cases where there is deterioration in brightness and variations in brightness, which can be thought to be caused by the variations in the electron emission characteristics. Hence, it is difficult to produce an excellent display image with high definition over a long period of use of the apparatus.

So, in view of the above problems, one object of the present invention is to provide an electron-emitting device having electron emission characteristics having stability for a long time. At the same time, another object of the present invention is to provide a method for manufacturing an electron-emitting device having electron emission characteristics having stability for a long time with ease and excellent controllability. Moreover, still another object of the present invention is to provide an electron source having electron emission characteristics having stability for a long time and a method for manufacturing the same. At the same time, still another object of the present invention is to provide an image display apparatus having a long life and a method for manufacturing the same.

So, the present invention has been made to solve the foregoing problems. The present invention is an electron-emitting device which includes a first conductive film and a second conductive film that are arranged on a base body with a gap between them and in which an electric potential of the second conductive film is made higher than an electric potential of the first conductive film to emit an electron, and the electron-emitting device is characterized in that: the base body includes a first part and a second part; the second part has a lower thermal conductivity than the first part and is arranged adjacently to the first part; the first conductive film is formed on the first part and the second conductive film is formed on the second part; and at least part of the gap is located above a boundary between the first part and the second part.

Further, the present invention is an electron-emitting device which includes a first conductive film and a second conductive film that are arranged separately from each other on a base body and in which an electric potential of the second conductive film is made higher than an electric potential of the first conductive film to emit an electron, and the electron-emitting device is characterized in that: the base body includes a first part and a second part; the second part has a lower thermal conductivity than the first part and is arranged adjacently to the first part; the first conductive film is formed on the first part and the second conductive film is formed on the second part; and at least part of a boundary between the first part and the second part is located between the first conductive film and the second conductive film.

The present invention is characterized also by an electron source including a plurality of electron-emitting devices of the present invention described above and by an image display apparatus including the foregoing electron source and a light-emitting substance.

The present invention is characterized also by an information reproducing apparatus including at least a receiver that outputs at least one of image information, character information, and voice information, which are included in a received broadcast signal, and the foregoing image display apparatus connected to the receiver.

The present invention is a method for manufacturing an electron-emitting device, and the method includes at least a first step for preparing a base body having a first electrode and a second electrode arranged separately from the first electrode and a second step for applying a pulse voltage between the first electrode and the second electrode a plurality of times in an atmosphere containing gas containing carbon, and is characterized in that: the base body includes a first part and a second part; that the second part has a lower thermal conductivity than the first part and is arranged adjacently to the first part; the first electrode and the second electrode are formed on the base body in such a way that a boundary between the first part and the second part is located between the first electrode and the second electrode; and the waveform of the pulse voltage includes a waveform that makes an electric potential of the first electrode higher than the electric potential of the second electrode and a waveform that makes the electric potential of the second electrode higher than the electric potential of the first electrode.

According to the present invention, excellent electron emission characteristics can be maintained for a long time. As a result, it is possible to provide an image display apparatus and an information display/reproduction apparatus capable of displaying a high-quality display image having little variation in brightness.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, an electron-emitting device and a method for manufacturing the same of the present invention will be described, but materials and values to be shown below are only examples. The materials and values to be shown below can be variously modified in such a way as to be suitable for applications if the modified materials and values are within a range that achieves the object of the present invention and produces the effect of the present invention.

Various preferred embodiments of the electron-emitting device of the present invention will be described below.

First Embodiment

First, the fundamental construction of a first embodiment of the most typical embodiment of the electron-emitting device of the present invention will be described with reference toFIGS. 13A to 13C.FIG. 13Ais a schematic plan view to show a typical construction in this embodiment.FIGS. 13B and 13Care schematic cross-sectional views along a line B-B′ and a line C-C′ inFIG. 13A.

In the embodiment shown inFIGS. 13A to 13Cis shown an embodiment in which a base body100is constructed of a substantially insulating substrate1, a first part5, and a second part6. The second part6has lower thermal conductivity than the first part5.

A first auxiliary electrode2and a second auxiliary electrode3are arranged on the base body100with a gap L1between them. The first auxiliary electrode2has a first conductive film30aconnected thereto and the second auxiliary electrode3has a second conductive film30bconnected thereto. Here, the auxiliary electrodes2,3are used for supplying the conductive films30a,30bwith an electric potential and hence can be omitted.

The first conductive film30ais opposite to the second conductive film30bacross a gap8. In other words, the first conductive film30aand the second conductive film30bare arranged separately from each other. For this reason, the gap8is located between the first auxiliary electrode2and the second auxiliary electrode3. Hence, at least part of the first conductive film30ais formed on the first part5and at least part of the second conductive film30bis formed on the second part6.

The gap8is located above the boundary between the first part5and the second part6. That is, the boundary of the first part5and the second part6is arranged between the first conductive film30aand the second conductive film30b(directly below the gap8). The width L2of the gap8is practically set to 1 nm to 10 nm so as to make a driving voltage 30 V or less in consideration of driver's cost and to prevent electric discharge from being developed by unexpected fluctuations in voltage at the time of drive.

Here, inFIG. 13, the first conductive film30aand the second conductive film30bare shown as two films that are completely separated from each other. However, the gap8has an extremely narrow width, as described above, so the integration of the gap8, the first conductive film30a, and the second conductive film30bcan be expressed as “a conductive film having a gap”. For this reason, the electron-emitting device of the present invention can be called an electron-emitting device that emits electrons when a voltage is applied across one end and the other end edge of the conductive film having a gap at the time of drive.

Moreover, there are also cases where the first conductive film30aand the second conductive film30bare connected to each other in an extremely small area. The extremely small area can be allowed because the area has high resistance and hence produces only a limited effect on the electron emission characteristics. An embodiment in which the first conductive film30aand the second conductive film30bare connected to each other in a part in this manner can be also expressed as “a conductive film having a gap”.

InFIG. 13Ais shown an example in which the gap8is formed in a straight shape. The gap8is preferably formed in the straight shape but is not limited to the straight shape. The gap8may be formed in a specified shape such as a shape bent at specified intervals, a circular arc shape, or a shape of a combination of a circular arc and a straight line.

Here, the gap8is constructed in such a way that the end edge (outer edge) of the first conductive film30ais opposite to the end edge (outer edge) of the second conductive film30b.

When this electron-emitting device is driven (emits electrons), a higher electric potential is applied to the second auxiliary electrode3than to the first auxiliary electrode2. It is thought that this electron-emitting device has many electron-emitting parts in a portion which is a portion of the end edge of the first conductive film30aand constructs the outer edge of the gap8. It is thought that the first conductive film30aconnected to the first auxiliary electrode2corresponds to an emitter. That is, it is thought that many electron-emitting parts exist in the portion which is the portion of the end edge of the first conductive film30aand constructs the outer edge of the gap8.

The gap8can be formed also by subjecting the conductive film to various kinds of high-definition working processes of nano scale such as an FIB (focused ion beam). For this reason, the gap8of the electron-emitting device of the present invention is not limited to a gap formed by “current passing forming” processing or “activation” processing which will be described later.

In this regard, inFIGS. 13A to 13Cis shown the embodiment in which the base body100is constructed of the substrate1, and the first part5and the second part6that are formed on the substrate1separately. However, the first part5and the second part6may be formed as parts of the substrate1.

However, as described above, the second part6is lower in thermal conductivity than the first part5. Moreover, a third part that is different in thermal conductivity from the first part5and the second part6may be arranged in an area where the auxiliary electrodes2,3and the conductive films30a,30bare not arranged on the substrate1. Such an area is, for example, an area except for an area under the first auxiliary electrode2and the second auxiliary electrode3or an area except for an area between the first auxiliary electrode2and the second auxiliary electrode3.

The employment of this construction can suppress deterioration with elapse of time in the electron emission characteristics. This reason is not clear but it can be thought that the existence of the first part2having high thermal conductivity under the first conductive film30acorresponding to the emitter can suppress a temperature increase in the first conductive film30awhen the electron-emitting device is driven. With this, while the electron-emitting device is driven, the quantum mechanical tunnel phenomenon of the electron from the first conductive film30acan be stably developed. Moreover, it is thought that since the second part6having lower thermal conductivity exists directly under the second conductive film30bnear the gap8, when the electron-emitting device is driven, the temperature of the second conductive film30bcan be kept high by the collisions of electrons tunneling from the first conductive film30a. This can prevent the remaining gas from being adsorbed by the surface of the second conductive film30band hence can suppress a secular change in the surface of the second conductive film30b. For this reason, in the electron-emitting device of the present invention, it is thought that when the electron-emitting device is driven, the electron emission characteristics can be made stable and the life of electron emission current Ie (or brightness) is elongated and a driving state is stabilized.

To produce the foregoing effect, at least a part of the gap8needs to be located above the boundary between the first part5and the second part6. That is, the boundary between the first part5and the second part6needs to be located in the gap8. Of course, as shown inFIG. 13A, it is preferable that the boundary between the first part5and the second part6is surely located between the first conductive film30aand the second conductive film30bin an X-Y plane. However, an embodiment in which a part of the gap8deviates from the boundary between the first part5and the second part6is not excluded, if the part is within a range capable of producing the effect of the present invention.

For this reason, practically, it is preferably that the boundary between the first part5and the second part6is located inside the gap8in an area of 80% or more of the area (gap8) between the first conductive film30aand the second conductive film30bin the X-Y plane of the electron-emitting device. In other words, practically, it is preferable that the boundary between the first part5and the second part6exists in a cross section of 80% or more of many cross sections (X-Z plane) of the electron-emitting device passing the gap8between the first and second conductive films30aand30b. Alternatively, in still other words, it is preferable that the area of 80% or more of the area (gap8) between the first conductive film30aand the second conductive area30bin the X-Y plane of the electron-emitting device is separated by the boundary between the first part5and the second part6.

In this regard, the embodiment has been shown here in which the first part5is in direct contact with the first conductive film30aand in which the second part6is in direct contact with the second conductive film30b. However, another layer may be arranged between the first part5and the first conductive film30aand between the second part6and the second conductive film30b, if this construction can produce the same effect of the present invention. Further, the first part5and the second part6are not necessarily homogeneous across their entire extensions, if this construction can produce the same effect of the present invention.

A conductive material such as metal and semiconductor can be used as the material of the conductive films30a,30b. For example, metal such as Pd, Ni, Cr, Au, Ag, Mo, W, Pt, Ti, Al, and Cu, or alloys of these metals or carbon can be used. In particular, because the conductive film30a,30bcan be formed by the “activation” processing, which will be described later, it is preferable that the conductive film30a,30bare carbon films.

It is preferable that the conductive film30a,30bare formed in such a way as to have a sheet resistance Rs of 102Ω/ or more and 107Ω/ or less. Specifically, a film thickness showing the foregoing resistance is preferably 5 nm or more and 100 nm or less. Here, the sheet resistance value Rs is a value appearing when it is assumed that the resistance R of a film, which has a thickness of t, a width of w, and a length of 1, measured in the longitudinal direction of the film is equal to Rs (1/w), and if resistivity is assumed to be ρ, Rs=ρ/t. Further, the width W′ of the conductive films30a,30bis preferably set narrower than the width W of the auxiliary electrodes2,3(seeFIG. 13A). By setting the width W wider than the width W′, variations in distance between the auxiliary electrodes2,3and the respective electron-emitting parts can be reduced. Although the value of width W′ is not limited to a particular value, the value is preferably within a practical range of 10 μm or more to 500 μm or less.

Here, the main roles of the first auxiliary electrode2and the second auxiliary electrode3are to act as terminals for applying a voltage to the conductive films30a,30b, so the first auxiliary electrode2and the second auxiliary electrode3can be omitted if there is another means for applying a voltage to the gap8.

As the substrate1can be used a quartz glass substrate, a blue glass substrate, a glass substrate formed of a glass substrate and silicon oxide (typically SiO2) laminated on the glass substrate, or a glass substrate in which alkali component is reduced.

The first part5and the second part6are constructed of a substantially insulating material. This is because if the first part5and the second part6are substantially conductive substances, a strong electric field cannot be developed in the gap8and hence electrons cannot be emitted in the worst case. Moreover, if the first part5and the second part6have high conductivity, there is a possibility that when unexpected electric discharge occurs at the time of the “activation” processing or at the time of driving the electron-emitting device, a current strong enough to destroy the electron-emitting parts may flow through the gap8. For this reason, it is important that the first part5and the second part6are substantially insulating materials.

Further, it is important that the first part5and the second part6are lower in electric conductivity (typically have higher sheet resistance value or higher resistance value) than the conductive films30a,30b. It is preferable that the resistivity of the material constructing the first part5and the second part6is practically 108Ωm or more. In consideration of a thickness to be described later, it is preferable that the sheet resistance value of the first part5and the second part6is practically 1013Ω/ or more. To realize this sheet resistance value, practically, it is preferable that the first part5and the second part6are formed of material having a specific resistance of 108μm or more.

As the material of the first part5is selected material having higher thermal conductivity than the substrate1and the second part6. Specifically, silicon nitride, alumina, aluminum nitride, tantalum pentoxide, or titanium oxide can be used as the material of the first part5.

It suffices that the second part6is lower in thermal conductivity than the first part5, for example, preferably, the second part6contains silicon oxide (typically, SiO2). In particular, preferably, the second part6is mainly formed of silicon oxide. When the second part6is mainly formed of silicon oxide, practically, the silicon oxide contained by the second part6is 80 wt % or more, preferably, 90 wt % or more.

Further, depending on the material, the thicknesses (thicknesses in a Z direction inFIG. 13) of the first part5and the second part6are preferably 10 nm or more so as to effectively produce the effect of the present invention, more preferably, 100 nm or more. Moreover, the thickness does not have an upper limit from the effect but preferably is 10 μm or less in terms of the stability of the process and the thermal stress of the substrate1.

The gap L1in the direction (X direction) in which the first auxiliary electrode2and the second auxiliary electrode3are opposite to each other and the film thicknesses of the first and second auxiliary electrodes2,3are designed as appropriate according to the applications of the electron-emitting device. For example, when the electron-emitting devices are used for an image display apparatus such as a television set to be described late, the gap L1and the thicknesses are designed according to resolution. In particular, a high-definition television set needs to have high definition, so a pixel size needs to be reduced. For this reason, to produce sufficient brightness in a state where the size of the electron-emitting device is limited, the gap L1and the thicknesses are designed so as to produce a sufficient electron emission current Ie.

The gap L1in the X direction of the first auxiliary electrode2and the second auxiliary electrode3(direction in which the first auxiliary electrode2and the second auxiliary electrode3are opposite to each other) is practically set to 10 nm or more and 100 μm or less, preferably, to 50 nm or more and 5 μm or less. The auxiliary electrodes2,3practically have a thickness of 100 nm or more and 10 μm or less.

As the material of the auxiliary electrodes2,3can be used a conductive material such as metal and semiconductor. For example, metal such as Ni, Cr, Au, Mo, W, Pt, Ti, Al, Cu, and Pd, or alloys of these metals, and metal such as Pd, Ag, Au, RuO2, Pd—Ag or metal oxide of these metals can be used. The conductive films30a,30bare thinner than the auxiliary electrodes2,3, so the auxiliary electrodes2,3have sufficient higher thermal conductivity than the conductive film30a,30b.

Second Embodiment

The fundamental construction of a second embodiment of a modification of the electron-emitting device of the present invention will be described with reference toFIG. 1. The same parts as the parts used inFIG. 13are denoted by the same reference numerals.

This embodiment is an embodiment in which the conductive films30a,30bshown in the first embodiment are constructed of electrodes4a,4band conductive films21a,21b. In this embodiment, a first electrode4aconnects the auxiliary electrode2and the first conductive film21a, and a second electrode4bconnects the auxiliary electrode3to the second conductive film21b. The first electrode4aand the second electrode4bare opposite to each other across a second gap7and a boundary between the first part5and the second part6is located directly under the second gap7. Further, like the first embodiment, the conductive films21a,21bare opposite to each other across the gap8and the boundary between the first part5and the second part6is located directly under the gap8. It is preferable that the conductive films21a,21bare carbon films. Even this embodiment can produce the effect of providing excellent electron emission characteristics for a long time with stability. Further, if the electrodes4a,4bhave higher resistance than the conductive films21a,21b, it is possible to further stabilize the electron emission characteristics.

Third Embodiment

The fundamental construction of a third embodiment of a modification of the electron-emitting device of the present invention will be described with reference toFIG. 3.FIG. 3Ais a schematic plan view andFIG. 3Bis a cross-sectional view along a line B-B′ inFIG. 3A. InFIG. 3, the same parts as the parts described in the first and second embodiments are denoted by the same reference numerals. In this embodiment, the size of L1and the materials and sizes of the respective parts are the same as those described in the first and second embodiments.

The electron-emitting device of this embodiment shown inFIG. 3corresponds to an electron-emitting device such that the direction in which the first conductive film21aand the second conductive film21bin the electron-emitting device described in the second embodiment are opposite to each other is arranged in such a way as to cross (preferably, be substantially vertical to) the surface of the substrate1.

More specifically, the first part5, the second part6, and the second auxiliary electrode3are laminated on the substrate1. Also in this embodiment, the base body100is constructed of the first part5, the second part6, and the substrate1.

For this reason, the second gap8is arranged on the side surface (side surface of the first part5) of a laminated body constructed of the first part5, the second part6, and the second auxiliary electrode3. This embodiment is essentially the same in the other points as the second embodiment shown inFIG. 1. Moreover, even this embodiment shown inFIG. 3can produce the effect of providing excellent electron emission characteristics for a long time with stability.

Further, as shown inFIG. 3C, the end portion of the first auxiliary electrode2can be separated from the end portion of the first part5. This makes it possible to elongate the distance between the first auxiliary electrode2and the first carbon film21a, that is, the distance between the first auxiliary electrode2and the second gap8.

In this regard, in the embodiment shown here, the side surface of the laminated body on which the second gap8is arranged is arranged substantially vertically to the surface of the substrate1.

In the first embodiment, the direction in which the first conductive film30aand the second conductive film30bare opposite to each other is the direction of the plane of the substrate1(X direction).

However, it is preferable from the viewpoint of improving electron emission efficiency (η) that the direction in which the first conductive film21aand the second conductive film21bare opposite to each other is vertical to the surface of the substrate1.

When the electron-emitting device of the present invention is driven, as will be described with reference toFIG. 5, an anode electrode44is arranged apart in the Z direction from the plane of the substrate1.

For this reason, like this embodiment, when the direction in which the first conductive film21aand the second conductive film21bare opposite to each other is directed to the anode electrode44, the electron emission efficiency (η) can be enhanced. In this regard, the electron emission efficiency (η) means a value expressed by electron emission quantity (Ie)/device current (If). Here, the electron emission quantity (Ie) is current flowing into the anode electrode44, and the device current (If) can be specified by current flowing between the first auxiliary electrode2and the second auxiliary electrode3.

However, in this embodiment, the side surface of the laminated body is not limited to a surface vertical to the surface of the substrate1. Effectively, it is preferable that the side surface of the laminated body is set to an angle of 30 degrees or more to 90 degrees or less with respect to the surface of the substrate1.

When the electron-emitting device of the present embodiment is driven, the electric potential of the second auxiliary electrode3is set higher than the electric potential of the first auxiliary electrode2. Hence, the electron-emitting device of the present embodiment is driven, as described in the first embodiment, the first conductive film21aconnected to the first auxiliary electrode2side becomes an electron emitting body (emitter). For this reason, when the second part6directly under the second electrode4bhas a highly insulating property, even if electric discharge is developed, it is possible to suppress damage to the electron emitting part.

Moreover, the structure of the base body100shown in this embodiment can be applied to the structure of the base body100of the first embodiment. That is, in this case, the first electrode4aand the first conductive film21ashown inFIG. 3are replaced by the first conductive film30aand the second electrode4band the second conductive film21bare replaced by the second conductive film30b.

Next, a method for manufacturing an electron-emitting device of the present invention will be described.

By taking the electron-emitting device of the second embodiment as an example, one embodiment of the manufacturing method of the present invention will be specifically described below with reference toFIG. 2. The manufacturing method of the present invention can be performed, for example, by the following processes 1 to 5.

The substrate1is sufficiently cleaned, and the first part5and the second part6are formed on the substrate1by the use of a photolithography technology (including resist coating, exposing, developing, and etching). Then, material for forming the second part6is deposited by a vacuum evaporation method, a sputtering method, or a CVD method. Then, the material is lifted off by the use of a separating agent to prepare the base body100having the first part5and the second part6formed thereon (FIG. 2A).

At this time, it is preferable that the surface of the second part6and the surface of the first part5(that is, the surface of the base body100) are formed in a nearly flat plane. However, if the film thickness of the conductive film4to be formed in a process 3 to be described later is not specially changed, the surfaces may be formed in a slightly uneven plane.

Further, here, an embodiment has been shown in which the first part5and the second part6are formed on the substrate1. However, one or both of the first part5and the second part6may be formed on a portion of the substrate1. Still further, as for the materials and sizes of the first part5, the second part6, and the substrate1, it suffices to suitably apply the materials and sizes described in the foregoing embodiments to them.

Next, material for forming the auxiliary electrodes2,3is deposited by the vacuum evaporation method, the sputtering method, or the like. Then, the material is patterned by the use of the photolithography or the like to form the first auxiliary electrode2and the second auxiliary electrode3on the base body100(FIG. 2B).

At this time, the first auxiliary electrode2and the second auxiliary electrode3are formed in such a way that the boundary between the first part5and the second part6is located between the first auxiliary electrode2and the second auxiliary electrode3. As for the material, the film thickness, the gap L1, and the width W of the auxiliary electrodes2,3, it suffices to apply the materials and the values described in the foregoing embodiments to them as appropriate. Here, in the present invention, the auxiliary electrodes2,3can be also omitted.

Subsequently, the conductive film4for connecting the first auxiliary electrode2and the second auxiliary electrode3, which are formed on the base body100, is formed (FIG. 2C). By this process 3, the conductive film4is formed across the first part5and the second part6.

As a method for manufacturing the conductive film4can be employed the following method: for example, first, an organic metal solution is applied and dried to form an organic metal film; then, the organic metal film is heated and baked to form a metal compound film such as a metal film or a metal oxide film; and then, the metal compound film is patterned by lifting-off or etching to produce the conductive film4.

As the material of the conductive film4can be conductive material such as metal or semiconductor. For example, metal such as Ni, Cr, Au, Mo, W, Pt, Ti, Al, Cu, or Pd, or metal compound (alloy or metal oxide) of them.

A method for coating an organic metal solution has been described here, but the method for forming the conductive film4is not limited to this method. The conductive film4can be also formed by a publicly known method, for example, the vacuum evaporation method, the sputtering method, the CVD method, a diffusion coating method, a dipping method, a spinner method, or an ink jet method.

When the “current passing forming” processing is performed in the next process, the conductive film4is formed so as to have a sheet resistance Rs of 102Ω/ or more and 107Ω/ or less. Here, the sheet resistance Rs is a value appearing when it is assumed that the resistance R of a film, which has a thickness of t, a width of w, and a length of l, measured in the longitudinal direction of the film is equal to Rs (l/w), and if resistivity is assumed to be ρ, Rs=ρ/t. The film thickness showing the foregoing resistance value is practically 5 nm or more and 50 nm or less. Further, the width W′ of the conductive film4(seeFIG. 1) is set narrower than the widths W of the auxiliary electrodes2,3. The process 3 can be also replaced in order by the process 2.

Subsequently, the first gap7is formed in the conductive film4. A patterning method using an EB lithography method can be employed as a method for forming the gap7. Further, a FIB (Focused Ion Beam) is directed on a portion where the gap7of the conductive film4is desired to be formed to form the gap7at a predetermined portion of the conductive film4(portion located above the boundary between first part5and the second part6). In other words, the boundary between first part5and the second part6can be located directly under the gap7(the boundary between first part5and the second part6can be exposed in the gap7). Further, in still other words, the boundary between the first part5and the second part6can be located between the first electrode4aand the second electrode4bthat are arranged separately from each other.

Of course, the gap7can be also formed in a portion of the conductive film4by passing current through the conductive film4by the publicly known “current passing forming” processing. The current can be passed through the conductive film4, specifically, by applying a voltage between the first auxiliary electrode2and the second auxiliary electrode3. When the first auxiliary electrode2and the second auxiliary electrode3are not used, “the current passing forming” processing can be performed by applying a voltage across both ends of the conductive film4.

However, there are cases where it is difficult to control the position of the gap7by “the current passing forming” processing. For this reason, when the gap7is formed by “the current passing forming” processing, it is preferable to make a portion of the conductive film4where the first gap7is desired to be formed have high resistance and then to perform “the current passing forming” processing.

By this process, the first electrode4aand the second electrode4bare arranged opposite to each other in the X direction across the first gap7(FIG. 2D). That is, the first electrode4aand the second electrode4bare arranged separately from each other on the base body100. Here, there are also cases where the first electrode4aand the second electrode4bare connected to each other by a small portion.

The base body100subjected to the foregoing processes 1 to 3 is put in a vacuum unit shown inFIG. 5and the vacuum unit is evacuated to a vacuum. And then processing after the process 4 is performed.

In this regard, a measurement evaluation unit shown inFIG. 5has the vacuum unit (vacuum chamber) and the vacuum unit is provided with devices necessary for the vacuum unit such as an exhaust pump and a vacuum meter (not shown). In the interior of the vacuum unit, various kinds of measurements and evaluations can be performed under a desired vacuum.

Further, when this measurement evaluation unit is provided with a gas introduction unit (not shown), gas containing carbon that is used in the “activation” processing to be described later can be introduced into the vacuum unit at a desired pressure. Still further, the entire vacuum unit and the base body100arranged in the vacuum unit can be heated by a heater (not shown).

The “current passing forming” processing can be performed by repeatedly applying a pulse voltage, in which a pulse crest value is a constant voltage, across the first auxiliary electrode2and the second auxiliary electrode3. Further, the “current passing forming” processing can be performed also by repeatedly applying a pulse voltage while gradually increasing its pulse crest value. An example of a pulse shape when the pulse crest value is constant is shown inFIG. 6A. InFIG. 6A, reference numerals T1and T2denote a pulse width and a pulse interval (quiescent time) of a voltage waveform. T1can be set to a range from 1 μsec to 10 msec, and T2can be set to a range from 10 μsec to 100 msec. A triangular waveform or a rectangular waveform can be used as the shape of the pulse voltage to be applied.

Next, an example of a pulse shape in which a pulse voltage is applied while increasing the pulse crest value is shown inFIG. 6B. InFIG. 6B, reference numerals T1and T2denote a pulse width and a pulse interval (quiescent time) of the voltage waveform. T1can be set to a range from 1 μsec to 10 msec, and T2can be set to a range from 10 μsec to 100 msec. A triangular waveform or a rectangular waveform can be used as the shape of the pulse voltage to be applied. The crest value of the applied pulse voltage is increased, for example, by a step of about 0.1 V.

In the example described above, a pulse voltage having a triangular waveform is applied across the first auxiliary electrode2and the second auxiliary electrode3. However, the shape of the pulse voltage to be applied across the first auxiliary electrode2and the second auxiliary electrode3is not limited to the triangular waveform but a desired waveform such as a rectangular waveform may be used. Further, the pulse crest value, the pulse width, and the pulse interval are not limited to the foregoing values, but suitable values can be selected in accordance with the resistance value of the electron-emitting device or the like so as to form the first gap7in a good shape.

Next, the conductive films4a,4bare subjected to the “activation” processing (FIG. 2E).

The “activation” processing is performed, for example, by introducing gas containing carbon into the vacuum unit shown inFIG. 5and by applying a bipolar pulse voltage as shown inFIG. 7AandFIG. 7Bacross the auxiliary electrodes2,3a plurality of times in an atmosphere containing the gas containing carbon. That is, the bipolar pulse voltage is applied across the first electrode4aand the second electrode4bthe plurality of times in the atmosphere containing the gas containing carbon.

By this processing, a carbon film (a first carbon film21aand a second carbon film21b) can be formed on the base body100by the gas containing carbon existing in the atmosphere. Specifically, the carbon film21a,21bare deposited on the base body100between the first electrode4aand the second electrode4band the first electrode4aand the second electrode4bnear the base body100. That is, the first carbon film21aand the second carbon film21barranged separately from the first carbon film21aare formed on the base body100.

When the foregoing method is employed, the second gap8can be located above the boundary between the first part5and the second part6, although the reason is not known in detail. In other words, the boundary between the first part5and the second part6can be located in the gap8. Alternatively, in still other words, the boundary between the first part5and the second part6can be located between the first carbon film21aand the second carbon film21b.

As the gas containing carbon can be used, for example, an organic substance gas. Examples of the organic substance include a class of aliphatic hydrocarbon of alkane, alkene, and alkyne, a class of aromatic hydrocarbon, a class of alcohol, a class of aldehyde, a class of ketone, a class of amine, and a class of organic acid such as phenolic acid, carboxylic acid, and sulfonic acid. Specifically, saturated hydrocarbon expressed by a composition formula of CnH2n+2such as methane, ethane, and propane, and unsaturated hydrocarbon expressed by a composition formula of CnH2nsuch as ethylene, propylene can be used. Further, benzene, toluene, methanol, ethanol, formaldehyde, acetaldehyde, acetone, methyl ethyl ketone, methyl amine, ethyl amine, phenol, formic acid, acetic acid, propionic acid can be also used. In particular, trinitryl is preferably used.

The waveform of the bipolar pulse voltage to be applied during the “activation” processing is a waveform in which the relationship between the electric potential of the auxiliary electrode2or the first electrode4aand the electric potential of the auxiliary electrode3or the second electrode4bis reversed at predetermined timings or at predetermined periods (seeFIG. 7A,7B). It is preferable that the relationship of the electric potential is alternately reversed, but the present invention is not limited to the alternately reversed waveform.

The application of the bipolar pulse voltage can be realized, for example, in the following manner. That is, a pulse voltage for making the electric potential of the auxiliary electrode2or the first electrode4ahigher than the electric potential of the auxiliary electrode3or the second electrode4bis applied. Then, a pulse voltage for making the electric potential of the auxiliary electrode2or the first electrode4alower than the electric potential of the auxiliary electrode3or the second electrode4bis applied. It is preferable that this operation is repeatedly performed. Here, it can be freely set which of the electric potential of the auxiliary electrode2or the first electrode4aand the electric potential of the auxiliary electrode3or the second electrode4bis first made a higher electric potential.

It is preferable that a maximum voltage value (absolute value) to be applied is selected as appropriate within a range of from 10 V to 25 V.

InFIG. 7A, reference numeral T1denotes the pulse width of a pulse voltage to be applied and T2denotes a pulse interval. In this example is shown a case where the absolute values of positive and negative voltage values are equal to each other, but there are also cases where the absolute values of positive and negative voltage values are different from each other. Further, inFIG. 7B, reference numeral T1denotes the pulse width of a pulse voltage of a positive voltage value and T1′ denotes the pulse width of a pulse voltage of a negative voltage value. Reference numeral T2denotes a pulse interval. In this example is shown a case where T1>T1′ and where the absolute values of positive and negative voltage values are equal to each other, but there are also cases where the absolute values of positive and negative voltage values are different from each other. It is preferable that the “activation” processing is finished after an increase in the device current (If) becomes gentle.

Further, even if which of waveforms shown inFIG. 7is used, the “activation” processing is performed until an increase in the device current (If) becomes gentle, whereby the gap8can be formed above the boundary between the first part5and the second part6as shown inFIG. 2E.

The electron-emitting device shown inFIG. 1can be formed by the foregoing processes 1 to 5.

When the electron-emitting device of the embodiment shown inFIG. 13is formed, the foregoing process 4 is not performed. The gap L1between the first auxiliary electrode2and the second auxiliary electrode3in the process 3 is set to 50 nm or more and 5 μm or less and then the “activation” processing described in the process 5 is performed. With this, the carbon films30a,30bcan be formed and the gap8can be formed above the boundary between the first part5and the second part6(the boundary between the first part5and the second part6is formed in the gap8).

The manufactured electron-emitting device is preferably subjected to “stabilizing” processing that is heating processing in a vacuum before the electron-emitting device is driven (before an electron beam is directed upon a light-emitting substance when the electron-emitting device is applied to the image display apparatus).

It is preferable that extra carbon and organic substance attached to the surface or other portion of the base body100by the foregoing “activation” processing are removed by the “stabilizing” processing.

Specifically, the extra carbon and the organic substance are exhausted in the vacuum unit. It is desirable to remove the organic substance in the vacuum unit as much as possible. Preferably, the partial pressure of the organic substance is reduced to 1×10−8Pa or less. Further, the total pressure of the atmosphere in the vacuum chamber including other gas except for the organic substance is preferably reduced to 3×10−6Pa or less.

It is preferable that the atmosphere when the “stabilizing” processing is finished is kept also when the electron-emitting device is driven after the “stabilizing” processing is performed, but the atmosphere when the electron-emitting device is driven after the “stabilizing” processing is performed is not limited to this atmosphere. If the organic substance is sufficiently removed, even if the pressure itself is slightly increased, sufficiently stable characteristics can be kept. The electron-emitting device of the present invention can be formed in the foregoing processes.

Further, the electron-emitting device of the embodiment shown inFIG. 3Bcan be formed, for example, in the following manner. One example will be described with reference toFIG. 4.

First, a material layer constructing the first part5and a material layer constructing the second part6are laminated in this order on the substrate1described in the foregoing process 1. These material layers can be deposited on the substrate1by the vacuum evaporation method, the sputtering method, or the CVD method. Next, a material layer constructing the second auxiliary electrode3is deposited on the material layer constructing the second part6by the vacuum evaporation method, the sputtering method, or the CVD method (seeFIG. 4A).

Then, a laminated body having a stepped shape is formed on a portion of the surface of the substrate1by publicly known patterning method such as a photolithography technology (FIG. 4B).

Next, the first auxiliary electrode2is formed on the substrate1(FIG. 4C).

Subsequently, the conductive film4is formed by the same process 3 described above so as to cover the side surface of the laminated body and to connect the first auxiliary electrode2and the second auxiliary electrode3(FIG. 4D).

Then, the same processing as in the processes 4 and 5 described above is performed (FIGS. 4E,4F).

In this manner, the electron-emitting device of the embodiment shown inFIG. 3Bcan be formed. Moreover, the embodiment shown inFIG. 3Cis different from the embodiment shown inFIG. 3Bonly in that the end portion of the second auxiliary electrode3is shifted in position, so the embodiment shown inFIG. 3Ccan be formed by performing the patterning process in addition to the foregoing forming method.

In this regard, the method for manufacturing the electron-emitting device of the foregoing embodiment shown here is only one example. It is not intended to limit the electron-emitting devices of the foregoing first and second embodiments to the electron-emitting device manufactured by these manufacturing methods.

Next, the fundamental characteristics of the foregoing electron-emitting device of the present invention will be described with reference toFIG. 8. A typical example of the relationship between the electron emission current Ie and the device current If of the electron-emitting device of the present invention and a device voltage Vf to be applied across the auxiliary electrodes2,3is shown inFIG. 8, the electron emission current Ie and the device current If being measured by the measurement evaluation unit shown inFIG. 5.

Here, the electron emission current Ie is extremely smaller than the device current If, and they are shown by respective arbitrary units. As is clear fromFIG. 8, the electron-emitting device of the present invention has three properties relating to the electron emission current Ie.

First, when a device voltage of a specified voltage or more (which is called threshold voltage; Vth inFIG. 8) is applied to the electron-emitting device of the present invention, the electron emission current Ie is rapidly increased, whereas the device voltage is the threshold or less, the electron emission current Ie is hardly detected. That is, the electron-emitting device of the present invention is a non-linear device having a definite threshold voltage Vth to the electron emission current Ie.

Secondly, since the electron emission current Ie depends on the device voltage Vf, the electron emission current Ie can be controlled by the device voltage Vf.

Thirdly, the emitted electric charges captured by the anode electrode44depend on the time during which the device voltage Vf is applied to the electron-emitting device. In other words, the quantity of electric charges captured by the anode electrode44can be controlled by the time during which the device voltage Vf is applied to the electron-emitting device.

The electron emission characteristics can be easily controlled according to an input signal by the use of the foregoing characteristics of to the electron-emitting device.

Next, the application of the electron-emitting device of the present invention shown in the first and second embodiments will be described below.

An electron source and an image display apparatus such as a flat panel type television set can be constructed by arraying a plurality of electron-emitting devices of the present invention on the substrate.

A pattern of arraying the electron-emitting devices on the substrate includes, for example, a matrix type array. In this pattern of array, the foregoing first auxiliary electrode2is electrically connected to one of m lines of X-direction wiring arrayed on the substrate, whereas the foregoing second auxiliary electrode3is electrically connected to one of n lines of Y-direction wiring arrayed on the substrate. Here, both of m and n are positive integers.

Next, the construction of an electron source substrate of this matrix type array will be described with reference toFIG. 9.

The m lines of X-direction wiring72include Dx1, Dx2, . . . , and Dxm and are formed on the insulating substrate71by the vacuum evaporation method, a printing method, or the sputtering method. The m lines of X-direction wiring72are formed of conductive material such as metal. The n lines of Y-direction wiring73include Dy1, Dy2, . . . , and Dyn and can be formed by the same method and of the same material as the X-direction wiring72. An insulating layer (not shown) is arranged between (at the intersections of) the m lines of X-direction wiring72and the n lines of Y-direction wiring73. The insulating layer can be formed by the vacuum evaporation method, the printing method, or the sputtering method.

Further, scanning signal application means (not shown) for applying a scanning signal is electrically connected to the X-direction wiring72, whereas modulation signal production means (not shown) for applying a modulation signal for modulating an electron emitted from the selected electron-emitting device74in synchronization with the scanning signal is electrically connected to the Y-direction wiring73. The driving voltage Vf to be applied to each electron-emitting device is supplied as a difference voltage between the scanning signal and the modulation signal that are to be applied to the electron-emitting device.

Next, one example of an electron source and an image display apparatus that use the electron source substrate of the matrix type array described above will be described with reference toFIG. 10andFIG. 11.FIG. 10is a fundamental construction diagram of an enclosure (display panel)88constructing an image display apparatus, andFIG. 11is a schematic diagram to show the construction of a luminescent film.

InFIG. 10, a plurality of electron-emitting devices74of the present invention are arrayed in the shape of a matrix on the electron source substrate (rear plate)71. A face plate86is a plate such that a luminescent film84and a conductive film85are formed on the inner surface of a transparent substrate83such as glass. A support frame82is arranged between the face plate86and the rear plate71. The rear plate71, the support frame82, and the face plate86are joined to each other by applying an adhesive such as frit glass or indium to the joins of them. The enclosure (display panel)88is constructed of this joined structural body. Here, the foregoing conductive film85is a member corresponding to the anode44described with reference toFIG. 5.

The enclosure88can be constructed of the face plate86, the support frame82, and the rear plate71. Further, the enclosure88having sufficient strength against the atmospheric pressure can be constructed by placing a support body (not shown) called a spacer between the face plate86and the rear plate71.

FIGS. 11A and 11Bare specific construction examples of the luminescent film84shown inFIG. 10. In the case of constructing a monochrome image display apparatus, the luminescent film84is consisted of only a monochromatic fluorescent substance92. In the case of constructing a color image display apparatus, the luminescent film84includes at least fluorescent substances92of three primary colors of red, green, and blue, and light absorption members91arranged between the respective colors. A black member can be preferably used as the light absorption member91.FIG. 11Ashows a pattern in which the light absorption members91are arranged in the shape of stripes.FIG. 11Bshows a pattern in which the light absorption members91are arranged in the shape of a matrix. Generally, the pattern shown inFIG. 11Ais called “black stripes” and the pattern shown inFIG. 11Bis called “black matrix”. The object of arranging the light absorption members91is to prevent color mixture in color separation portions, which are located between the respective fluorescent substances92of three primary colors required in the case of color display, from standing out and to prevent the luminescent film84from reflecting external light to decrease contrast. As for the material of the light absorption member91, not only material having graphite as a main component, which is usually often used, but also any material that hardly transmits and reflects light can be used. Further, the material of the light absorption member91may be conductive material or insulating material.

Further, a conductive film85called “metal back” or the like is disposed on the inner surface side (the electron-emitting device74side) of the luminescent film84. One object of disposing the conductive film85is to surface reflect light, which is to be directed to the electron-emitting device74from the fluorescent substance92, to the face plate86to enhance brightness. Further, another object of disposing the conductive film85is to make the conductive film85act as an anode for applying an electron beam acceleration voltage and to prevent negative ions generated in the enclosure88from colliding with the fluorescent substance to cause damage to the fluorescent substance.

It is preferable that the conductive film85is formed of an aluminum film. The conductive film85can be manufactured in the following manner: the luminescent film84is manufactured; then, processing of smoothing the surface of the luminescent film84is performed (this processing is usually referred to as “filming” processing); and then aluminum Al is deposited by the vacuum evaporation method or the like.

The face plate86may have a transparent electrode (not shown), which is made of ITO or the like, formed between the luminescent film84and the transparent substrate83so as to further enhance the conduction of the luminescent film84.

The respective electron-emitting devices74in the enclosure88are connected to the X-direction wiring72and the Y-direction wiring73, as shown inFIG. 9. For this reason, by applying a voltage to the respective electron-emitting devices74through the terminals Dox1to Doxm, Doy1to Doyn, which are connected to the electron-emitting devices74, it is possible to emit electrons from the desired electron-emitting devices74. At this time, a voltage that is 5 kV or more and 30 kV or less, preferably, 10 kV or more and 25 kV or less is applied to the conductive film85through a high-voltage terminal87. Here, the gap between the face plate86and the substrate71is set to 1 mm to 5 mm, preferably, not smaller than 1 mm and not larger than 3 mm. In this manner, the electrons emitted from the selected electron-emitting devices pass through the metal back85and collide with the luminescent film84to excite the fluorescent substance92to emit light, thereby displaying an image.

In this regard, in the foregoing construction, the detailed contents such as material and size of the respective parts are not limited to the contents described above but may be modified as appropriate according to the object.

Further, an information display/reproducing apparatus can be constructed by the use of the enclosure (display panel)88of the present invention described with reference toFIG. 10.

Specifically, the information display/reproducing apparatus includes a receiving unit and a tuner for tuning a received signal and outputs a signal included in a tuned signal to the display panel88to display or reproduce the signal on a screen. The receiving unit can receive a broadcast signal such as television broadcast signal. The signal included in the tuned signal designates at least one of image information, character information, and voice information. Here, it can be said that the “screen” corresponds to the luminescent film84in the display panel88shown inFIG. 10. With this construction, the information display/reproducing apparatus such as a television set can be constructed. Of course, when the broadcast signal is encoded, the information display/reproducing apparatus of the present invention can include also a decoder. Further, a voice signal is outputted to voice reproduction means such as a speaker provided separately and is reproduced in synchronization with the image information and the character information displayed on the display panel88.

Furthermore, a method for outputting image information and character information to the display panel88to display and/or reproduce the information on the screen can be performed, for example, in the following manner. First, image signals corresponding to the respective pixels of the display panel88are produced from the received image information and character information. Then, the produced image signals are inputted to a drive circuit C12of a display panel C11. Then, a voltage to be applied to the respective electron-emitting devices in the display panel88is controlled by the drive circuit C12based on the image signals inputted to the drive circuit C12to display an image.

FIG. 12is a block diagram of a television set according to the present invention. A receiving circuit C20of a receiver includes a tuner, a decoder, and the like, and receives a television signal such as satellite broadcast and terrestrial waves, data broadcast through a network, and the like, and outputs decoded image data to an IF unit (interface unit) C30. The I/F unit C30converts image data to a display format of the display apparatus and outputs the image data to a display panel C11. An image display apparatus C10includes the display panel C11, a drive circuit C12, and a control circuit C13. The control circuit C13subjects the inputted image data to image processing of correction processing or the like suitable for the display panel and outputs the image data and various control signals to the drive circuit C12. The drive circuit C12outputs a driving signal to the wiring (see Dox1to Doxm, Doy1to Doyn inFIG. 10) of the display panel C11based on the inputted image data, whereby a television image is displayed. The receiving circuit C20and the I/F unit C30may be housed as a set top box (STB) in a box separate from the image display apparatus10or may be housed in the same box as the image display apparatus10.

Further, the interface unit C30can be constructed so as to be connected to an image recording device and an image output device such as a printer, a digital video camera, a digital camera, a hard disk drive (HDD), and a digital video disk (DVD). With this construction, an image recorded in the image recording device can be also displayed on the display panel C11. Moreover, an information reproducing apparatus (or television set) that can process the image displayed on the display panel C11, if necessary, and can output the image to the image output device can be also constructed.

The construction of the information reproducing apparatus described above is only one example and can be variously modified based on the technology philosophy of the present invention. Moreover, when the information reproducing apparatus of the present invention is connected to a teleconference system and a computer system, various information reproducing apparatuses can be constructed.

Hereinafter, the present invention will be described in more detail by examples.

In this example will be shown an example in which the electron-emitting device described in the first embodiment was manufactured. The construction of the electron-emitting device of this example is the same as that inFIG. 1. The fundamental construction of an electron-emitting device of this example and a method for manufacturing the electron-emitting device will be described below with reference toFIG. 1andFIG. 2.

First, a photoresist layer having an opening corresponding to the pattern of a second part6was formed on a cleaned quartz substrate1. Then, the depressed portion of a pattern corresponding to the second part6was formed on the surface of the substrate1by a dry etching method. Five substrates1were prepared in this manner.

Then, Si3N4was deposited in the depressed portion corresponding to the second part6of each of the substrates1. Si3N4was formed by a plasma CVD method. In this example, a first part5was formed of quartz.

At the same time, a quartz substrate to be used for measuring resistivity and thermal conductivity was prepared and the foregoing material was deposited on this quartz substrate in the same way as the foregoing method, and then the resistivity and thermal conductivity of the materials were measured. The measurement results were as follows.

The resistivity of Si3N4at room temperature was 1×1013Ωm and the thermal conductivity of Si3N4at room temperature was 25 W/m·k. The resistivity and thermal conductivity of the quartz substrate1were 1×1014Ωm or more and 1.4 W/m·k.

The foregoing material was deposited in such a way that the surfaces of the second part6and the first part5were made nearly flat.

Next, the photoresist pattern was dissolved by an organic solvent to lift off the film deposited on the photoresist to produce a base body100in which the second part6and the first part5were arranged adjacently to each other (FIG. 2A).

Further, a substrate having the first part5and the second part6not formed thereon (that is, only quartz substrate1) was prepared as a Comparative example 1. Still further, a substrate1in which Si3N4was deposited on the surface of a quartz substrate1without being patterned (in this case, the second part6was formed on the whole surface of the base body) was also prepared as a Comparative example 1′.

Next, the auxiliary electrodes2,3were formed of Ti and Pt on each of the base bodies100of this example and the comparative examples, the Pt being formed on the Ti. The gap L1was set to 20 μm.

Here, the boundary between the first part5and the second part6was formed nearly in the center between the auxiliary electrodes2,3. The widths W (seeFIG. 1) of the auxiliary electrodes2,3were set to 500 respectively (FIG. 2B).

Subsequently, while the respective base bodies100subjected to the process-a and the process-b were rotated, they were coated with an organic palladium compound solution and then were heated and baked. The conductive films4, each of which had Pd as a main element, were formed in this manner. Subsequently, the conductive films4were patterned, thereby being formed in such a way as to connect the first auxiliary electrodes2and the second auxiliary electrodes3(FIG. 2C). The formed conductive films4had a sheet resistance Rs of 1×104Ω/ and had a thickness of 10 nm.

Next, the respective base bodies100subjected to the foregoing processes from the process—a to the process-c were put in the vacuum chamber. Then, a FIB was continuously directed upon the boundary between the first part5and the second part6to form a first gap7in the conductive film4, whereby electrodes4a,4bwere formed (FIG. 2D).

Subsequently, “activation” processing was performed. Specifically, trinitryl was introduced into the vacuum unit. Then, a pulse voltage of the waveform shown inFIG. 7Awas applied across the auxiliary electrodes2,3under following conditions: a maximum voltage was ±20V; T1was 1 msec; and T2was 10 msec. After the “activation” processing was started and it was recognized that the device current If started to increase gently, applying the pulse voltage was stopped to finish the “activation” processing. As a result, the carbon films21a,21bwere formed (FIG. 2E). The boundary between the first part5and the second part6was located in and along the gap8between the first carbon film21aand the second carbon film21b. The electron-emitting device was formed in the processes described above.

In this manner, the respective base bodies100having the second part6formed of Si3N4and the respective base bodies100formed as the Comparative example 1 and the Comparative example 1′ were subjected to the same processes of the process-b to the process-e. Further, ten electron-emitting devices were formed on each of the base bodies100by the same method.

Further, in this example, the resistivity of each of the materials used for the second part6was 108Ωm or more, so an electric discharge causing large damage was not developed during the “activation” processing.

Next, the respective electron-emitting devices were subjected to the “stabilization” processing. Specifically, the vacuum unit and the electron-emitting devices were heated by a heater and the vacuum unit was kept evacuated with the temperature held at about 250° C. Heating the vacuum unit by the heater was stopped after 20 hours and then the vacuum unit was returned to room temperature, whereby pressure in the vacuum unit reached about 1×10−8Pa.

Subsequently, the electron emission current Ie and the brightness of each electron-emitting device were measured by the measurement unit shown inFIG. 5.

The distance H between the anode electrode44and the electron-emitting device was made 4 mm and an electric potential 1 kV was placed to the anode electrode44by a high-voltage power source43. In this state, a rectangular pulse voltage having a crest value of 17 V was applied between the auxiliary electrodes2,3by the use of the power source41so as to make the electric potential of the first auxiliary electrode2lower than the electric potential of the second auxiliary electrode3. Then, the device current If and the electron emission current Ie of the electron-emitting device of this example and those of the Comparative example 1 were measured by an ampere meter40and an ampere meter42.

A stable electron emission current Ie could not be measured for the electron-emitting device of the Comparative example 1′. It is thought that this is because the “activation” processing was used for the manufacturing process whereas silicon oxide was not used directly below the gap8for the electron-emitting device of the Comparative example 1′. That is, it is estimated that because the electron-emitting device of the Comparative example 1′ could not be subjected to the sufficient “activation” processing, a stable electron emission current Ie could not be measured.

Table 1 shows a comparison of electron emission current, electron emission efficiency, and drive time that passed until the electron emission current decreased one-half between the electron-emitting device of this Example 1 and the electron-emitting device of the Comparative example 1 with reference to the values of the electron-emitting device of the Comparative example 1. As shown in Table 1, the electron-emitting device according to the present invention could keep excellent electron emission characteristics for a long time. In this regard, when the characteristics of the electron-emitting device of this Example 1 were evaluated in the same way with the electric potential of the first auxiliary electrode2made higher than the electric potential of the second auxiliary electrode3, all of the electron emission current, the electron emission efficiency, and the drive time that passed until the electron emission current decreased one-half decreased.

In this example will be shown an example in which the electron-emitting device described in the second embodiment was manufactured. The fundamental construction of the electron-emitting device according to this example is the same as shown inFIG. 3B. A method for manufacturing an electron-emitting device of this example will be described below with reference toFIG. 3andFIG. 4.

First, five cleaned quartz substrate1were prepared. Then, Si3N4was deposited as material for forming the first part5on each of the substrates1. Si3N4was formed by the plasma CVD method. At the same time, the foregoing material was deposited also on another substrate to be used for measuring resistivity and thermal conductivity, and then the resistivity and thermal conductivity of the materials were measured. The measurement values were the same as those of the Example 1. Then, silicon oxide (SiO2) was deposited as material for forming the second part6on all of the substrates1by the plasma CVD method. At the same time, SiO2was deposited also on a substrate to be used for measuring resistivity and thermal conductivity, and then the resistivity and thermal conductivity of the materials were measured. The measurement values were the same as those of the Comparative example 1.

Further, Ti and Pt were deposited in this order in a thickness of 5 nm and in a thickness of 45 nm as materials for forming the auxiliary electrode3on the second part6(seeFIG. 4A).

Thereafter, the substrate was coated with photoresist while it was spun and then was exposed to a mask pattern and was developed. Then, the substrate was subjected to dry etching, whereby a laminated body constructed of the first part5and the second part6and the second auxiliary electrode3arranged on the laminated body were formed (seeFIG. 4B).

Next, the substrate had the photoresist removed and then was again coated with photoresist while it was spun, and then was exposed to a mask pattern and then developed, whereby the photoresist having an opening corresponding to the pattern of the first auxiliary electrode2was formed. Subsequently, Ti and Pt were further deposited in sequence in a thickness of 5 nm and in a thickness of 45 nm in the opening. Then, the photoresist was lifted off to form the first auxiliary electrode2(seeFIG. 4C).

The widths W of the auxiliary electrode3and the auxiliary electrode2were made 500 μm, respectively. The film thickness of the second part6was made 50 nm and the film thickness of the first part5was made 500 nm.

Further, there was prepared also a substrate1having the second part6not formed thereon and having only a SiO2layer (first part) formed between the surface of the substrate1and the second auxiliary electrode3(Comparative example 2). Still further, there was prepared also a substrate1having the first part5not formed thereon and having only a Si3N4layer (second part) formed between the surface of the substrate1and the first auxiliary electrode2(Comparative example 2′).

As for the subsequent processes, the substrates were subjected to the same processes as the process-c to process-f in the Example 1, whereby the electron-emitting devices were formed. Just as with the Example 1, also in this example, ten electron-emitting devices were formed on each of the substrates.

Further, also in this example, the resistivity of the foregoing material used for forming the second part6was 108Ωm or more and hence large electric discharge was not developed during the “activation” processing.

Subsequently, the electron emission currents Ie and the brightness of the respective electron-emitting devices were measured by the use of the measurement unit shown inFIG. 5.

The distance H between the anode electrode44and the electron-emitting device was made 4 mm and an electric potential of 1 kV was applied to the anode electrode44by a high-voltage power source43. In this state, a rectangular pulse voltage having a crest value of 17 V was applied between the auxiliary electrodes2,3by the use of the power source41. Then, the device current If and the electron emission current Ie of the electron-emitting device of this example and those of the comparative examples were measured by the ampere meter40and the ampere meter42.

A stable electron emission current Ie could not be measured for the electron-emitting device of the Comparative example 2′. It is thought that this is because the “activation” processing was used for the manufacturing process whereas silicon oxide was not used directly below the gap8for the electron-emitting device of the Comparative example 2′. That is, it is estimated that because the electron-emitting device of the Comparative example 2′ could not be subjected to the sufficient “activation” processing, a stable electron emission current Ie could not be measured.

Table 2 shows a comparison of electron emission current, electron emission efficiency, and drive time that passed until the electron emission current decreased one-half between the electron-emitting device of this Example 2 and the electron-emitting device of the Comparative example 2 with reference to the values of the electron-emitting device of the Comparative example 2. As shown in Table 2, the electron-emitting device according to the present invention could keep excellent electron emission characteristics for a long time. In this regard, when the characteristics of the electron-emitting device of this Example 2 were evaluated in the same way with the electric potential of the first auxiliary electrode2made higher than the electric potential of the second auxiliary electrode3, all of the electron emission current, the electron emission efficiency, and the drive time that passed until the electron emission current decreased one-half decreased.

This example is an example in which many electron-emitting devices formed by the same method as the method for manufacturing an electron-emitting device in the Example 1 were arranged in the shape of a matrix on a substrate to form an electron source. Further, this example is also an example in which an image display apparatus shown inFIG. 10was manufactured by the use of this electron source. A process for manufacturing an image display apparatus formed in this example will be described.

A silicon oxide film was formed on a glass substrate71. A photoresist was formed on the silicon oxide film in correspondence with the pattern of the first part5. Then, a depressed portion corresponding to the second part6was formed by the dry etching method. Then, Si3N4was deposited as material of the second part6by the plasma CVD method in such a way as to make the surface of second part6nearly flush with the surface of the silicon oxide film. Then, the photoresist was dissolved by an organic solution to lift off the deposited film, whereby a substrate71having the second part6and the first part5arranged adjacently to each other was produced. Here, in this example, the first part5was formed of the silicon oxide.

(Process for Forming Auxiliary Electrode)

Next, many auxiliary electrodes2,3were formed on the substrate71(FIG. 14). Specifically, a laminated film of titanium Ti and platinum Pt was formed in a thickness of 40 nm and was patterned by a photolithography method to form the many auxiliary electrodes2,3. In this example, the boundary between the first part5and the second part6was arranged in the center between the auxiliary electrodes2,3. Further, the gap L1between the auxiliary electrodes2,3was made 10 μm and the length W of the gap L1was made 200 μm.

Next, as shown inFIG. 15A, Y-direction wiring73having silver as a main component were formed in such a way as to be connected to the auxiliary electrodes3. This Y-direction wiring73function as wiring having a modulation signal applied thereto.

Next, as shown inFIG. 15B, to insulate X-direction wiring72to be formed in the next process from the Y-direction wiring73, insulating layers75formed of silicon oxide were arranged. The insulating layers75were arranged under the X-direction wiring72to be described later in such a way as to cover the previously formed Y-direction wiring73. Contact holes were formed in portions of the insulating layers75in such a way that the X-direction wiring72could be electrically connected to the auxiliary electrodes2.

As shown inFIG. 15C, X-direction wiring72having silver as a main component were formed on the previously formed insulating layers75. The X-direction wiring72cross the Y-direction wiring73across the insulating layers75and were connected to the auxiliary electrodes2at the contact holes of the insulating layers75. This X-direction wiring72function as wiring having a scanning signal applied thereto. The substrate71having matrix wiring was formed in this manner.

Conductive films4were formed between the auxiliary electrodes2and the auxiliary electrodes3on the substrate71having the matrix wiring formed thereon by an ink jet method (FIG. 15D). In this example, an organic palladium complex solution was used as ink used for the ink jet method. This organic palladium complex solution was applied in such a way as to connect the auxiliary electrodes2and the auxiliary electrodes3. Then, this substrate71was heated and baked in the air to produce the conductive films4made of palladium oxide (PdO).

Thereafter, just as with the Example 1, the gaps7were formed in the respective conductive films4and then the substrate71was subjected to the “activation” processing. In the “activation” processing, the waveform of voltage to be applied to each unit was the same as shown in the method for manufacturing an electron-emitting device of the Example 1.

By the foregoing processes, the substrate71having the electron source (the plurality of electron-emitting devices) of this example was formed.

Next, as shown inFIG. 10, a face place86in which a luminescent film84and a metal back85were laminated on the inner surface of a glass substrate83was arranged 2 mm above the substrate71via a support frame82.

Then, the join of the face plate86and the support frame82and the join of the support frame82and the substrate71were joined by heating and cooling indium (In) of metal having a low melting point. Further, this joining process was performed in a vacuum chamber, so joining and sealing were performed at the same time without using an exhaust pipe.

In this example, the luminescent film84of an image forming member was a fluorescent substance formed in the shape of stripes so as to produce a color display (seeFIG. 11A). First, black stripes91were formed at desired intervals. Subsequently, respective fluorescent substances92were applied between the black stripes91by a slurry method to produce the luminescent film84. Material having graphite as a main component was used as the material of the black stripes91, the graphite being usually used as the material.

Further, a metal back85made of aluminum was formed on the inner surface side (electron-emitting device side) of the luminescent film84. The metal back85was manufactured by vacuum evaporating aluminum Al on the inner surface side of the luminescent film84.

Desired electron-emitting devices were selected through the X-direction wiring and the Y-direction wiring of the image display apparatus completed in this manner and a pulse voltage of 14 V was applied to them. At the same time, a voltage of 10 kV was applied to the metal back85through a high-voltage terminal Hv. In this manner, a bright excellent image having little unevenness in brightness and also having little variation in brightness could be displayed for a long time.

The embodiments and examples described above are only examples of the present invention. It is not intended that various modifications of the materials and sizes described above are excluded from the present invention.

This application claims the benefit of Japanese Patent Application No. 2006-202140, filed Jul. 25, 2006, which is hereby incorporated by reference herein in its entirety.