JP4179470B2 - Electron-emitting device and method for manufacturing electron-emitting device - Google Patents

Description

  The present invention is used as an electron beam source in various devices using an electron beam, such as a display such as a field emission display (FED) and a backlight, an electron beam irradiation device, a light source, an electronic component manufacturing device, and an electronic circuit component. The present invention relates to an applicable electron-emitting device and a manufacturing method thereof.

  As is well known, the above-described electron-emitting device is operated in a vacuum having a predetermined degree of vacuum, and an emitter is formed by applying a predetermined electric field to an electron-emitting portion (hereinafter referred to as an emitter portion). Electrons are emitted from the part. When this electron-emitting device is applied to an FED, a plurality of electron-emitting devices are two-dimensionally arranged, and a plurality of phosphors are arranged at a predetermined distance from the electron-emitting devices so as to correspond to the plurality of electron-emitting devices. Are arranged respectively. Then, by selectively driving one of the plurality of electron-emitting devices arranged in a two-dimensional array, an electron is emitted from the electron-emitting device at an arbitrary position. By colliding with the phosphor, fluorescence is emitted from the phosphor at an arbitrary position, so that a desired display can be performed.

  Specific examples of this electron-emitting device include the following Patent Documents 1 to 5. In these specific examples, since a fine conductor electrode is used as the emitter portion, fine processing such as etching or forming is required to form the fine conductor electrode, and the manufacturing process is complicated. Become. In addition, a high voltage must be applied for electron emission, and there is a problem that the cost of components such as an IC for high voltage driving increases. As described above, the specific example has a problem that the manufacturing cost of the electron-emitting device and the device to which the electron-emitting device is applied are increased.

  In view of this, an electron-emitting device having an emitter portion made of a dielectric material has been devised and disclosed in, for example, Patent Documents 6 and 7 below. Further, general knowledge regarding electron emission when the dielectric is used as the emitter is disclosed in Non-Patent Documents 1 to 3 below.

The electron-emitting devices disclosed in Patent Documents 6 and 7 (hereinafter simply referred to as “conventional electron-emitting devices”) cover a part of the upper surface of an emitter portion made of a dielectric with a cathode electrode, It is configured by arranging a grounded anode electrode on the lower surface of the emitter section or on the upper surface of the emitter section at a position spaced apart from the cathode electrode. That is, the electron-emitting device is configured such that an exposed portion of the surface of the emitter portion where neither the cathode electrode nor the anode electrode is formed is present near the outer edge portion of the cathode electrode on the upper surface side of the emitter portion. First, as a first step, a voltage is applied between the cathode electrode and the anode electrode so that the cathode electrode has a higher potential, and the emitter portion (particularly, the above-described electric field) is generated by the electric field formed by the applied voltage. (Exposed portion) is set to a predetermined polarization state. Next, as a second stage, a voltage is applied between the cathode electrode and the anode electrode so that the cathode electrode has a lower potential. At this time, primary electrons are emitted from the outer edge portion of the cathode electrode, the polarization of the emitter portion is inverted, and the primary electrons collide with the exposed portion of the emitter portion where the polarization is inverted, thereby causing the emitter Secondary electrons are emitted from the part. The secondary electrons fly in a predetermined direction by a predetermined electric field from the outside, whereby electrons are emitted by the electron-emitting device.
JP-A-1-315333 JP 7-147131 A JP 2000-285801 A Japanese Patent Publication No.46-20944 Japanese Examined Patent Publication No. 44-26125 JP 2004-146365 A Japanese Patent Application Laid-Open No. 2004-172087 Yasuoka, Ishii, "Pulsed electron source using a ferroelectric cathode" Applied Physics Vol.68, No.5, p546-550 (1999) VFPuchkarev, GAMesyats, On the mechanism of emission from theferroelectric ceramic cathode, J. Appl. Phys., Vol. 78, No. 9, 1 November, 1995, p. 5633-5637 H.Riege, Electron emission ferroelectrics-a review, Nucl. Instr. And Meth. A340, p. 80-89 (1994)

  By the way, in the conventional electron-emitting device, when electrons are emitted from the cathode electrode toward the emitter, the electric field lines are concentrated on the surface of the cathode electrode and the electric field strength is increased. Electron emission occurs (Note that the electric field lines concentrate on the surface of the electrode as a conductor as described above, and the electric field strength of the portion where the electric field lines are concentrated increases. The location where this “electric field concentration” occurs is simply referred to as “electric field concentration portion” hereinafter.)

  Here, FIG. 18 schematically shows an example of a conventional electron-emitting device. In this conventional electron-emitting device 200, an upper electrode 204 is formed on the upper surface of the emitter section 202, and a lower electrode 206 is formed on the lower surface. The upper electrode 204 is formed in close contact with the emitter section 202. In this case, the electric field concentration portion is only the outer edge portion of the upper electrode 204 which is a so-called triple junction where the upper electrode 204, the emitter portion 202 and the vacuum intersect.

  However, since the peripheral portion of the upper electrode 204 is in close contact with the emitter portion 202, the electric field concentration portion which is an electron emission location is limited to the outer edge portion constituting the outer periphery of the upper electrode 204. Therefore, since the number of electron emission locations is limited, there is a certain limit because the drive voltage can be increased only to such an extent that dielectric breakdown of the emitter portion 202 does not occur even if the electron emission amount is increased. It was.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an electron-emitting device that can improve the amount of electron emission.

  In order to achieve the above-described object, an electron-emitting device according to the present invention includes an emitter portion made of a dielectric, a first electrode formed on a first surface of the emitter portion and having an opening, A second electrode formed on a second surface of the emitter section, and applying a driving voltage between the first electrode and the second electrode, thereby opening the opening section from the emitter section. The first electrode is disposed such that a surface of the opening facing the first surface and the first surface are spaced apart from each other. In addition, the shape of the opening is characterized in that the lines of electric force concentrate at the inner edge of the opening.

  As described above, the shape of the opening where electric lines of force are concentrated at the inner edge of the opening is, for example, a portion having an acute shape in a side sectional view on the inner wall surface of the opening, or the inner wall surface. This can be realized by attaching a projection or a conductive fine particle approximately equal to or smaller than the thickness of the first electrode in the opening. Further, the opening shape is formed so that the inner wall surface of the opening has a hyperboloid shape (particularly, a hyperboloid shape in which both the upper end and the lower end in a side sectional view of the inner edge portion of the opening have an acute angle). This is also possible. In addition, the shape of the opening in which the lines of electric force concentrate on the inner edge can be realized by various modes other than those described above.

  According to the above configuration of the invention, since the opening in the first electrode is separated from the first surface of the emitter, the first surface and the opening of the first electrode A gap (air gap) is formed between the first surface and the surface facing the first surface. Due to the generation of this gap, the capacitance of a virtual capacitor formed between the surface of the opening of the first electrode facing the first surface and the first surface of the emitter is It is smaller than when there is no gap. Therefore, most of the driving voltage is substantially applied to the gap portion, and the outer edge portion of the first electrode is compared with the configuration of the conventional electron-emitting device having no gap as described above. This increases the electric field strength of the opening.

  Moreover, according to the said structure of this invention, the said opening part in a said 1st electrode is spaced apart from the 1st surface of the said emitter part, The 1st surface of the said emitter part, and the said 1st electrode A gap (gap) is formed between the opening and the surface facing the first surface, and the shape of the opening in the first electrode is a hook shape (flange shape) in a side sectional view. And the shape of the said opening part is formed in the shape where an electric force line concentrates in the inner edge of the said opening part. As a result, in the opening, the triple point serving as the electric field concentration portion is generated at a position different from the inner edge of the opening, and an electric field concentration portion is also generated at the inner edge of the opening. Therefore, the number of electron emission locations can be increased.

  As described above, according to the above configuration of the present invention, a higher electric field strength can be obtained at the electric field concentration portion, more electric field concentration portions can be provided, and higher electric field concentration can be easily generated. it can. Therefore, it is possible to provide an electron-emitting device that can improve the amount of electron emission.

  Here, in the electron-emitting device of the present invention, in particular, as a first stage, by applying a driving voltage such that the first electrode has a lower potential than the emitter portion, Electrons are emitted (supplied) toward the emitter section, that is, electrons are accumulated on the emitter section (the emitter section is charged), and as a second stage, the first electrode is higher than the emitter section. It is preferable to perform an operation in which electrons accumulated on the emitter section are emitted by applying a driving voltage that becomes a potential. Such an operation can be performed as follows, for example.

  As the drive voltage applied between the first electrode and the second electrode, for example, a voltage applied in a pulse or alternating manner with respect to a predetermined reference potential (for example, 0 V) is used.

  First, in the first stage, a driving voltage that causes the first electrode to be lower than the reference potential and the second electrode to be higher than the reference potential is applied between the first electrode and the second electrode. Applied between. Then, due to the electric field generated by this driving voltage, the polarization direction of the emitter portion is changed to a direction in which positive charges appear on the first surface of the emitter portion, and electric field concentration occurs in the above-described electric field concentration portion. Electrons are supplied from the electrodes to the emitter section. As a result, electrons are accumulated in the portion corresponding to the opening in the first electrode on the first surface of the emitter portion by being attracted by the positive charges appearing on the surface of the portion. That is, a portion of the first surface of the emitter portion corresponding to the opening in the first electrode is charged. At this time, the first electrode functions as an electron supply source.

  Next, in the second stage, the drive voltage changes rapidly, and the drive voltage that causes the first electrode to be higher than the reference potential and the second electrode to be lower than the reference potential is Applied between the first electrode and the second electrode. Then, the polarization direction of the emitter section is reversed by the electric field generated by the driving voltage, and negative charges appear on the first surface of the emitter section. Thus, in the first stage, electrons attached to the portion corresponding to the opening of the first electrode in the first surface of the emitter portion receive electrostatic repulsion due to polarization reversal, so that Flying from the first surface, the flying electrons are emitted to the outside through the opening.

  According to such an operation, since the charge amount of the emitter section in the first stage is relatively easy to control, a stable electron emission amount can be obtained with high controllability.

  In addition, the opening portion of the first electrode that is separated from the first surface of the emitter section functions as a gate electrode or a focus electron lens for electrons emitted from the first surface of the emitter section. Therefore, the straightness of emitted electrons can be improved.

  In the above configuration, if a plurality of openings are formed in the first electrode, the electron emission from one electron-emitting device can be evenly suppressed in the region occupied by the first electrode. Can be a thing.

  The electron-emitting device according to the present invention includes the same emitter as described above, a first electrode, and a second electrode, and is driven between the first electrode and the second electrode. The device is configured to emit electrons when a voltage is applied, and has a shape having a longitudinal direction in a side sectional view, and the longitudinal direction is the first surface on the first surface of the emitter section. The first electrode is constituted by an aggregate of a plurality of conductive particles arranged along one surface, and the opening is constituted by outer edges of the plurality of conductive particles. It is characterized by.

  According to this configuration, the first electrode has conductive particles having a longitudinal direction in a side sectional view on the first surface of the emitter portion, and the longitudinal direction is on the first surface. A plurality of the openings are arranged so as to extend along the opening, and the opening is constituted by outer edges of the plurality of conductive particles. Therefore, the gap (gap) between the emitter part and the opening part of the first electrode as described above, and the saddle shape in the opening part of the first electrode can be easily realized.

  Here, examples of the conductive particles having the longitudinal direction in the sectional side view constituting the first electrode include, for example, scaly, disc-like, coil spring-like, hollow cylindrical particles, and a sectional side view. In addition, particles having various shapes such as rod-shaped, needle-shaped, hemispherical, oval, and semi-elliptical particles can be employed.

  Note that a plurality of conductive particles are arranged on the first surface of the emitter portion so that the longitudinal direction is along the first surface. At this time, the longitudinal direction is not necessarily the emitter portion. It is not necessary to be completely parallel to the first surface of the conductive particles. In general, the conductive particles are in a state of being “sleeped” to the extent that the gap and the ridge shape having the above-described effects are formed. What is necessary is just to be arrange | positioned on the 1st surface. For example, the angle formed between the longitudinal direction of the conductive particles in a side sectional view and the first surface of the emitter section may be approximately 30 degrees or less.

  In the electron-emitting device according to the present invention, the emitter is made of a polycrystal, and the first electrode is a collection of primary particles of the conductive particles and / or the primary particles 2. A plurality of secondary particles are formed on the first surface of the emitter section, and the length of the primary particles or secondary particles in the longitudinal direction in a side cross-sectional view is that of the polycrystalline body. It is preferable to be configured to be longer than the average grain size of the crystal grains.

  Here, in the case of a polycrystal, a recess is likely to occur at a crystal grain boundary. Therefore, if this concave portion is used, the above-described soot shape is likely to occur simply by arranging a plurality of primary particles or secondary particles of the conductive particles on the first surface of the emitter section. .

  In the electron-emitting device according to the present invention, it is preferable that the first electrode is made of graphite. The graphite powder is a conductive particle having a shape having a relatively sharp end, such as a scale shape or a scale shape. In other words, it has a shape having a longitudinal direction in a side sectional view. Therefore, if the first electrode is formed using this graphite powder, the gap (gap) between the emitter part and the opening of the first electrode as described above, It is possible to easily realize the shape of the ridge in the opening and the shape of the inner edge of the opening where the lines of electric force concentrate at the inner edge of the opening.

  In the electron-emitting device according to the present invention, it is preferable that the first electrode further includes conductive fine particles. Here, it is more preferable that the fine particles are exposed on the surface of the first electrode. As a result, the fine particles are present like protrusions on the surface of the first electrode, so that the fine particles can be an electric field concentration portion due to the effect of the protrusion shape, thereby further increasing the number of electron emission locations. Can do. More preferably, the fine particles are also attached to the first surface of the emitter portion corresponding to the opening. Thus, a minute float electrode made of the fine particles is provided on the emitter portion made of a dielectric. This float electrode is suitable for accumulating a large amount of electrons emitted from the first electrode to the emitter, and can further increase the amount of electrons emitted from the electron-emitting device. If the float electrode is composed of the fine particles, for example, when the first electrode is formed on the first surface of the emitter section, the material is formed on the first surface together with the material constituting the first electrode. The float electrode can be provided on the first surface of the emitter section by a simple process such as coating.

  In the electron-emitting device according to the present invention, it is preferable that the fine particles are made of silver. Thereby, the first electrode containing conductive fine particles can be realized easily and inexpensively. In particular, when graphite is used as the first electrode, and in the process of forming the first electrode, a heating step in an atmosphere containing oxygen gas is included, the heating step surrounds the silver fine particles. Graphite is oxidized and eroded. Thereby, the shape of the outer edge portion of the first electrode tends to have a sharp end portion or an opening portion by a through hole inside the electrode. Therefore, the electric field concentration portion can be further increased, and a more suitable electrode shape can be obtained.

  The electron-emitting device having the above-described configuration can be manufactured by the following manufacturing method.

  That is, preparing a paste in which conductive particles having a longitudinal direction in a side sectional view are dispersed in a dispersion medium, forming a film made of the paste on the first surface of the emitter section, The first electrode is formed by heating the film.

  Thereby, after the above-described film formation (by adjusting the viscosity and blending ratio of the paste as appropriate), until the heating to the film is completed, due to the effects of the self-weight of the conductive particles, the surface energy, etc. The conductive particles can be in a “sleeping” state, and have a gap (gap) between the emitter portion and the opening of the first electrode, or a saddle shape of the opening in the first electrode. The preferred electron-emitting device can be easily manufactured.

  In the above production method, it is preferable that conductive fine particles are dispersed in the dispersion medium when the paste is prepared. As a result, it is possible to easily manufacture an electron-emitting device having more electric field concentration portions and an improved electron emission amount as described above.

  As described above, according to the electron-emitting device of the present invention, high electric field concentration can be easily generated, and more electric field concentration portions can be provided. Therefore, it is possible to provide an electron-emitting device that can improve the amount of electron emission.

  Hereinafter, preferred embodiments of an electron-emitting device according to the present invention will be described with reference to the drawings.

  First, the electron emission device according to the present embodiment is an electron beam of various devices using an electron beam, such as a display, an electron beam irradiation device, a light source, an alternative use of an LED, an electronic component manufacturing device, and an electronic circuit component. Can be applied to the source.

  The electron beam in the electron beam irradiation apparatus has high energy and excellent absorption performance as compared with the ultraviolet light in the currently widely used ultraviolet irradiation apparatus. As application examples, in semiconductor devices, there are uses for solidifying insulating films when stacking wafers, uses for curing printing inks uniformly when printing is dried, and uses for sterilizing medical devices in packages. .

  The use as a light source is for high luminance and high efficiency specifications, for example, a light source use of a projector in which an ultra-high pressure mercury lamp or the like is used. When the electron-emitting device according to this embodiment is applied to a light source, it has features of downsizing, long life, high-speed lighting, and reduction of environmental load due to mercury-free.

  Alternative uses of LEDs include surface light source applications such as indoor lighting, automotive lamps, and traffic lights, and chip light sources, traffic lights, and backlights for small liquid crystal displays for mobile phones.

  Applications of the electronic component manufacturing apparatus include an electron beam source for a film forming apparatus such as an electron beam vapor deposition apparatus, an electron source for plasma generation (for activation of gas, etc.) in a plasma CVD apparatus, an electron source for gas decomposition application, etc. . In addition, there are vacuum microdevice applications such as terahertz drive high-speed switching elements and large current output elements. In addition, it is also preferably used as a light emitting device for exposing a photosensitive drum by a combination with printer parts, that is, a phosphor, and an electron source for charging a dielectric.

  As electronic circuit components, a large current output and a high amplification factor are possible, and therefore there are applications to digital elements such as switches, relays, and diodes, and analog elements such as operational amplifiers.

  First, the electron-emitting device according to the first embodiment will be described with reference to FIGS.

  FIG. 1 is an enlarged side sectional view of a part of the electron-emitting device 10A of the present embodiment. As shown in FIG. 1, the electron-emitting device 10 </ b> A is formed on a plate-like emitter portion 12 made of a dielectric and an upper surface 12 a that is a first surface of the emitter portion 12, and an opening portion 20. And the lower electrode 16 as the second electrode formed on the lower surface 12b which is the second surface of the emitter section 12. The upper electrode 14 and the lower electrode 16 are connected to a pulse generation source 18 that applies a drive voltage Va between the upper electrode 14 and the lower electrode 16.

  The electron-emitting device 10A accumulates the electrons supplied from the upper electrode 14 on the upper surface 12a corresponding to the opening 20, and then accumulates the electrons accumulated on the upper surface 12a through the opening 20. It is configured to discharge to the outside.

  In FIG. 1, a part of the electron-emitting device 10A corresponding to a part of the pair of upper electrode 14 and lower electrode 16 is illustrated. The electron-emitting device 10A operates in a predetermined vacuum atmosphere, and the degree of vacuum in the atmosphere (particularly the space above the upper surface 12a of the emitter 12 in FIG. 1) is, for example, 10 2 to 10. -6 Pa is preferred, more preferably 10 -3 to 10 -5 Pa.

  In this embodiment, the emitter section 12 is made of a polycrystalline material made of a dielectric material. The thickness h of the emitter section 12 shown in FIG. 1 is such that when a driving voltage is applied between the upper electrode 14 and the lower electrode 16, polarization inversion occurs in the emitter section 12 and dielectric breakdown does not occur. It is determined by the relationship with the drive voltage so as to obtain the electric field strength. For example, assuming that the dielectric breakdown voltage of the emitter section 12 is 10 kV / mm or more, and if 100 V is applied as the driving voltage, the thickness h of the emitter section 12 should theoretically be 10 μm or more. However, it is preferable to set the thickness h of the emitter portion to about 20 μm in view of the margin so that dielectric breakdown does not occur. The crystal grain size of the dielectric constituting the emitter section 12 is preferably 0.1 μm to 10 μm, more preferably 2 μm to 7 μm. In the example of FIG. 1, the particle size of the dielectric is 3 μm. The crystal grain size of the emitter section 12 can be obtained, for example, as an average diameter when the shape of each particle is approximated to a circle having the same area as the area in plan view.

  In the present embodiment, the lower electrode 16 has a thickness of 20 μm or less, and preferably 5 μm or less.

  In the present embodiment, the upper electrode 14 is formed to have a thickness t of 0.1 μm ≦ t ≦ 20 μm, and has a plurality of openings 20 through which the emitter 12 is exposed to the outside. Further, as described above, since the emitter section 12 is made of a polycrystalline material, the surface of the upper surface of the emitter section 12 has irregularities 22 formed by dielectric crystal grain boundaries. And the opening part 20 of the upper electrode 14 is formed in the part corresponding to the recessed part 24 in the grain boundary of the said dielectric material. In the example of FIG. 1, a case where one opening 20 is formed corresponding to one recess 24 is shown, but one opening 20 may be formed corresponding to a plurality of recesses 24. .

  As shown in FIG. 2, the opening 20 includes an opening 20 a formed by the inner edge of the opening 20 and a peripheral portion 26 that is a portion around the opening 20 a. In the upper electrode 14, a surface 26 a facing the emitter section 12 in the peripheral section 26 of the opening 20 is separated from the emitter section 12. That is, in the upper electrode 14, a gap 28 is formed between the emitter 26 and a surface 26 a facing the emitter 12 in the peripheral portion 26 of the opening 20, and the peripheral portion 26 of the opening 20 in the upper electrode 14 is formed. It has a shape formed into a bowl shape (flange shape). Therefore, in the following description, “the peripheral portion 26 of the opening 20 of the upper electrode 14” is referred to as “the flange portion 26 of the upper electrode 14”. The “surface 26 a of the upper electrode 14 facing the emitter portion 12 in the peripheral portion 26 of the opening 20” is referred to as “the lower surface 26 a of the flange portion 26 of the upper electrode 14”. In FIG. 1 to FIG. 6, the cross section of the convex portion 30 of the unevenness 22 of the grain boundary of the dielectric is typically shown in a semicircular shape, but is not limited to this shape.

  In the present embodiment, the upper surface 12 a of the emitter section 12, that is, the surface of the convex section 30 (also the inner wall surface of the concave section 24) at the dielectric grain boundary, and the lower surface 26 a of the flange section 26 of the upper electrode 14. The maximum angle θ is 1 ° ≦ θ ≦ 60 °. In addition, the maximum distance d along the vertical direction between the surface of the convex portion 30 (inner wall surface of the concave portion 24) and the lower surface 26a of the flange portion 26 of the upper electrode 14 at the dielectric grain boundary of the emitter portion 12 is 0 μm <d ≦ 10 μm.

  Furthermore, in this embodiment, the upper electrode 14 is comprised from many electroconductive particle 15 (for example, graphite) which has a scale-like shape, as shown in FIG. That is, the upper electrode 14 is arranged in a state in which a large number of conductive particles 15 are “sleeping” such that the longitudinal direction of the conductive particles 15 in a side sectional view is along the first surface 12 a of the emitter portion 12. It is formed by. Specifically, the angle formed between the longitudinal direction of the conductive particle 15 in a side sectional view and the first surface 12a of the emitter 12 (smooth virtual plane obtained by averaging the irregularities 22 due to the crystal grain boundaries) is approximately 30. Each conductive particle 15 is disposed on the first surface 12a so as to be less than or equal to a degree.

  In the present embodiment, the conductive particles 15 have a primary particle size (longest longitudinal length in a side sectional view) larger than the crystal grain size of the dielectric constituting the emitter 12. It is used. In the example of FIG. 1, considering that the crystal grain size of the emitter section 12 is 3 μm, the size of the primary particles of the conductive particles 15 is preferably about 5 μm or more.

  Moreover, the opening part 20 is comprised by the outer edge part 15a of many electroconductive particle 15 by planar view, as shown in FIG. That is, the opening 20 a in the opening 20 is formed by a space surrounded by the outer edge portions 15 a of the plurality of conductive particles 15, and the above-described flange portion 26 is configured by the outer edge portions 15 a of the plurality of conductive particles 15. Yes.

  In addition, a triple junction (formed by contact between the upper electrode 14, the emitter section 12 and the vacuum) at a contact portion between the upper surface of the emitter section 12, the upper electrode 14 and a medium (for example, vacuum) around the electron-emitting device 10 </ b> A. (3 points) 26c is formed. The triple junction 26c is a portion (electric field concentration portion) where electric field lines are concentrated (electric field concentration) when the drive voltage Va is applied between the upper electrode 14 and the lower electrode 16. Here, “concentration of electric field lines” means that the electric field lines are drawn from the lower electrode 16 when the upper electrode 14, the emitter section 12, and the lower electrode 16 are drawn as infinitely long flat plates in a side sectional view. It shall be the place where the lines of electric force generated at equal intervals are concentrated. The state of concentration of electric field lines (electric field concentration) can be easily simulated by numerical analysis using a finite element method. The triple junction 26 c is generated not only at the position corresponding to the opening 20 but also at the outer edge of the outer periphery of the upper electrode 14.

  Furthermore, in the present embodiment, the opening 20 has a shape such that the inner edge 26b of the opening 20 becomes an electric field concentration portion. Specifically, the shape of the opening portion 20 in a side sectional view of the flange portion 26 is sharpened at an acute angle toward the inner edge 26b that is the tip of the flange portion 26 (thickness gradually decreases). It is formed as follows. The upper electrode 14 having the shape of the opening 20 has the conductive particles 15 that are particles having a longitudinal direction in a side sectional view, and the conductive particles 15 in the longitudinal direction in the side sectional view as described above. By arranging in a “sleeping” state so that the direction is along the first surface 12 a of the emitter section 12, it can be formed by a simple method.

  Here, the opening 20 has an average diameter of 0.1 μm or more and 20 μm or less when the shape of the opening 20a is approximated to a circle having the same area as the area of the opening 20a in plan view. Is formed. The reason is as follows.

  As shown in FIG. 2, the upper electrode 14 is formed in a portion of the emitter section 12 where the polarization is inverted or changed in accordance with the drive voltage Va applied between the upper electrode 14 and the lower electrode 16 (see FIG. 1). A portion (first portion) 40 directly below and a portion (second portion) 42 corresponding to a region from the inner edge (inner circumference) of the opening 20 toward the inside of the opening 20, The generation range of the second portion 42 changes depending on the level of the driving voltage Va and the degree of electric field concentration in the portion. And if it is the range of the average diameter (0.1 micrometer or more and 20 micrometers or less) of the opening 20a in this embodiment, while the emission amount of the electron discharge | released by the opening part 20 can fully be earned, it will discharge | release an electron efficiently. Can do. That is, when the average diameter of the opening 20a is less than 0.1 μm, the area of the second portion 42, which is a main region contributing to electron emission by accumulating electrons supplied from the upper electrode 14, is reduced and emitted. The amount of electrons is reduced. On the other hand, when the average diameter of the opening 20a exceeds 20 μm, the ratio (occupancy) of the second portion 42 in the portion exposed from the opening 20 of the emitter portion 12 becomes small, and the electron emission efficiency decreases. .

  Next, the principle of electron emission of the electron emitter 10A will be described with reference to FIGS. In the present embodiment, as shown in FIG. 4, the drive voltage Va applied between the upper electrode 14 and the lower electrode 16 is set to 0 V, and the time T1 as the first stage is The lower electrode 16 is at a lower potential (negative voltage) V2, and the subsequent second time T2 is the upper electrode 14 at a higher potential than the lower electrode 16 (positive voltage) V1. A rectangular wave having a cycle of (T1 + T2) is used.

  In the initial state, the case where the emitter section 12 is polarized in one direction and the negative pole of the dipole faces the upper surface of the emitter section 12 (see FIG. 5A) is assumed.

  First, in the initial state where the reference voltage is applied, as shown in FIG. 5A, since the negative pole of the dipole faces the top surface of the emitter section 12, electrons are placed on the top surface of the emitter section 12. Almost no accumulation has occurred.

  Thereafter, when the negative voltage V2 is applied, the polarization is reversed (see FIG. 5B). By this polarization inversion, electric field concentration occurs at the inner edge 26b and the triple junction 26c, which are the electric field concentration portions, and electron emission (supply) from the electric field concentration portion of the upper electrode 14 toward the upper surface 12a of the emitter portion 12 occurs. For example, electrons are accumulated in a portion of the upper surface 12a exposed from the opening 20 of the upper electrode 14 or a portion near the flange portion 26 of the upper electrode 14 (see FIG. 5C). That is, the upper surface 12a is charged. This charging is possible until a certain saturation state is reached depending on the surface resistance value of the emitter section 12, but the charge amount can be controlled by the application time of the control voltage. Thus, the upper electrode 14 (particularly the electric field concentration portion) functions as an electron supply source to the emitter portion 12 (upper surface 12a).

  After that, once the negative voltage V2 becomes the reference voltage as shown in FIG. 6A, when the positive voltage V1 is further applied, the polarization is reversed again (see FIG. 6B), and due to the Coulomb repulsive force by the negative pole of the dipole. Then, the electrons accumulated in the upper surface 12a are emitted toward the outside through the opening 20a (see FIG. 6C).

  Electron emission is also performed at the outer edge of the upper electrode 14 at the outer peripheral portion without the opening 20 in the same manner as described above.

  In the present embodiment, as shown in FIG. 7, in electrical operation, a capacitor C <b> 1 by the emitter section 12 and an aggregate of a plurality of capacitors Ca by the gaps 28 are disposed between the upper electrode 14 and the lower electrode 16. The shape is formed. That is, the plurality of capacitors Ca by each gap 28 is configured as one capacitor C2 connected in parallel with each other, and in terms of equivalent circuit, the capacitor C1 by the emitter 12 is connected in series to the capacitor C2 by the aggregate. It becomes.

  Actually, the capacitor C1 by the emitter section 12 is not directly connected in series to the capacitor C2 by the aggregate, but is connected in series according to the number of openings 20 formed in the upper electrode 14, the total formation area, or the like. The capacitor component changes.

  Here, as shown in FIG. 8, for example, assuming that 25% of the capacitor C1 by the emitter section 12 is connected in series with the capacitor C2 by the aggregate, the capacity calculation is performed. First, since the gap 28 is vacuum, the relative dielectric constant is 1. The maximum interval d of the gaps 28 is 0.1 μm, the area S of one gap 28 is S = 1 μm × 1 μm, and the number of the gaps 28 is 10,000. Further, when the relative dielectric constant of the emitter section 12 is 2000, the thickness of the emitter section 12 is 20 μm, and the opposing area of the upper electrode 14 and the lower electrode 16 is 200 μm × 200 μm, the capacitance value of the capacitor C2 by the aggregate is 0.885 pF, The capacitance value of the capacitor C1 by the emitter section 12 is 35.4 pF. When the portion connected in series with the capacitor C2 due to the aggregate in the capacitor C1 due to the emitter section 12 is 25% of the total, the capacitance value of the portion connected in series (the capacitance value of the capacitor C2 due to the aggregate) (Capacitance value including) is 0.805 pF, and the remaining capacitance value is 26.6 pF.

  Since these serially connected portions and the remaining portions are connected in parallel, the overall capacitance value is 27.5 pF. This capacitance value is 78% of the capacitance value 35.4 pF of the capacitor C1 by the emitter section 12. That is, the overall capacitance value is smaller than the capacitance value of the capacitor C1 by the emitter section 12.

  As described above, the aggregate of the capacitors Ca by the plurality of gaps 28 has a relatively small capacitance value of the capacitor Ca by the gaps 28, and most of the applied voltage Va is obtained from the divided voltage with the capacitor C1 by the emitter section 12. Is applied to the gap 28, and in each gap 28, high output of electron emission is realized.

  Further, since the capacitor C2 formed by the aggregate has a structure connected in series to the capacitor C1 formed by the emitter section 12, the entire capacitance value is smaller than the capacitance value of the capacitor C1 formed by the emitter section 12. From this, it is possible to obtain preferable characteristics that electron emission is high output and overall power consumption is small.

  As described in detail above, in the electron-emitting device 10A according to the present embodiment, the triple junction 26c may be generated at a location different from the inner edge 26b of the upper electrode by forming the collar portion 26 on the upper electrode 14. Further, the opening 20 has a shape such that the inner edge 26b of the opening 20 becomes an electric field concentration portion. Therefore, the number of electric field concentration portions can be greatly increased as compared with the case without the flange portion 26. In particular, the flange portion 26 of the present embodiment is formed to be sharpened at an acute angle toward the inner edge 26b which is the tip of the flange portion 26, so that the shape of the inner edge 26b is a right angle or an obtuse angle. Also, it is possible to increase the degree of electric field concentration and increase the amount of accumulated electrons on the upper surface 12a of the emitter section 12.

  Further, on the upper surface 12a of the emitter portion 12, the maximum angle θ between the surface of the convex portion 30 (inner wall surface of the concave portion 24) at the dielectric grain boundary and the lower surface 26a of the flange portion 26 of the upper electrode 14 is 1 ° ≦ θ ≦ 60 °, and in the vertical direction between the surface of the convex portion 30 (inner wall surface of the concave portion 24) and the lower surface 26a of the flange portion 26 of the upper electrode 14 at the dielectric grain boundary of the emitter portion 12. Since the maximum distance d along the line is 0 μm <d ≦ 10 μm, the degree of electric field concentration in the gap 28 can be increased by these configurations, and the amount of accumulated electrons on the upper surface 12a of the emitter section 12 can be increased. It becomes possible to increase.

  Further, by forming the flange portion 26 described above, a gap 28 is formed between the lower surface 26 a of the upper electrode 14 facing the emitter portion 12 in the flange portion 26 of the opening 20 and the emitter portion 12. Due to the influence of the capacitance of the virtual capacitor at, most of the drive voltage Va is substantially applied to the gap 28, and the electric field at the opening 20 becomes stronger. Therefore, it is possible to reduce the absolute value of the drive voltage Va necessary for obtaining the same electric field strength at the opening 20.

  Further, since the collar portion 26 of the upper electrode 14 functions as a gate electrode (control electrode) such as a focus electron lens, the straightness of emitted electrons can be improved. This is advantageous in reducing crosstalk when a large number of electron-emitting devices 10A are arranged, for example, as an electron source of a display.

  In particular, in this embodiment, at least the upper surface 12a of the emitter section 12 is provided with irregularities 22 due to dielectric grain boundaries, and the upper electrode 14 has openings 20 at portions corresponding to the concave sections 24 in the dielectric grain boundaries. Since it was formed, the collar part 26 of the upper electrode 14 can be easily realized.

  In addition, since the plurality of openings 20 are formed in the upper electrode 14, electrons are emitted from each opening 20 and the outer edge of the outer periphery of the upper electrode 14. This makes it easier to control the electron emission and increases the electron emission efficiency.

  Thus, in the electron-emitting device 10A according to the present embodiment, high electric field concentration can be easily generated, more electron emission portions can be increased, and electric field strength can be increased. Therefore, it is possible to improve the amount of electron emission and increase the efficiency of electron emission, and it is possible to provide an electron-emitting device with low voltage driving and low power consumption and its application product.

  Next, a display 100 configured using the electron-emitting device 10A according to the present embodiment will be described with reference to FIG.

  In the display 100, as shown in FIG. 9, a transparent plate 130 made of, for example, glass or acrylic is disposed above the upper electrode 14, and transparent, for example, is formed on the back surface (the surface facing the upper electrode 14) of the transparent plate 130. A collector electrode 132 composed of electrodes is disposed, and a phosphor 134 is applied to the collector electrode 132. A bias voltage source 136 (collector voltage Vc) is connected to the collector electrode 132 through a resistor. In addition, the electron-emitting device 10A is naturally disposed in the vacuum space. The degree of vacuum in the atmosphere is preferably 10 @ 2 to 10 @ -6 Pa, more preferably 10 @ -3 to 10 @ -5 Pa.

  The reason for selecting such a range is that, in a low vacuum, (1) since there are many gas molecules in the space, it is easy to generate plasma, and if too much plasma is generated, a large amount of positive ions are generated in the upper electrode 14. And (2) the emission electrons collide with gas molecules before reaching the collector electrode 132, and the phosphor 134 is sufficiently excited by electrons sufficiently accelerated by the collector voltage Vc. This is because there is a risk that it will not be performed.

  On the other hand, in high vacuum, electrons are likely to be emitted from the point where the electric field concentrates, but there is a problem that the structure support and the vacuum seal portion become large, which is disadvantageous for miniaturization.

  Next, an electron-emitting device 10B according to a second embodiment will be described with reference to FIG.

  The electron-emitting device 10B according to the second embodiment has substantially the same configuration as the electron-emitting device 10A according to the first embodiment described above, but the conductive particles 15 constituting the upper electrode 14 are: Not only the primary particles 15 a but also the secondary particles 15 b exist on the upper surface 12 a of the emitter section 12. The length of the secondary particles 15b in the longitudinal direction in a side sectional view is larger than the crystal grain size of the polycrystalline body constituting the emitter section 12.

  The electron-emitting device 10B according to the second embodiment also has the same operations and effects as the electron-emitting device 10A according to the first embodiment described above.

  Further, an electron-emitting device 10C according to the third embodiment will be described with reference to FIG.

  The electron-emitting device 10C according to the second embodiment has substantially the same configuration as the electron-emitting devices 10A and 10B according to the first to second embodiments described above, but the upper electrode 14 has the above configuration. In addition to the similar conductive particles 15, the conductive particles 15 are composed of conductive fine particles 19. The conductive fine particles 19 are preferably substantially equal to or smaller than the thickness of the primary particles of the conductive particles 15 (width in the direction orthogonal to the longitudinal direction in a side sectional view). For example, when the thickness of the conductive particles 15 is about 2 μm, the average particle size of the conductive fine particles 19 is preferably 1 μm or less, more preferably 0.5 μm or less. Thereby, the conduction | electrical_connection between each electroconductive particle 15 in the same upper electrode 14 can be ensured easily.

  Here, as shown in FIG. 11, the conductive fine particles 19 are preferably exposed on the surface of the upper electrode 14, particularly at the flange 26. As a result, the conductive fine particles 19 are present like projections on the surface of the upper electrode 14, and the conductive fine particles 19 can also be an electric field concentration portion due to the effect of the protrusion shape. The number of electron supply locations for the upper surface 12a can be further increased. Further, it is more preferable that the conductive fine particles 19 are also attached to the upper surface 12 a of the emitter portion 12 corresponding to the opening 20. As a result, the minute float electrode made of the conductive fine particles 19 is provided on the emitter section 12 made of a dielectric. This float electrode is suitable for accumulating a large amount of electrons emitted from the upper electrode 14 to the emitter section 12, and can further increase the amount of electrons emitted from the electron-emitting device. If the float electrode is composed of the conductive fine particles 19, for example, the conductive particles 15 and the conductive fine particles 19 are mixed when the upper electrode 14 is formed on the upper surface 12 a of the emitter portion 12, as will be described later. The float electrode can be provided on the upper surface 12a of the emitter section 12 by a simple process such as coating on the upper surface 12a of the emitter section 12.

  Further, when a carbon-based material (for example, graphite) is used as the conductive particles 15 and silver is used as the conductive fine particles 19, when heat treatment is performed during the formation of the upper electrode 14, In addition, since the graphite and the like around the silver fine particles are eroded by oxidation, the shape of the outer edge portion of the upper electrode 14 tends to have a sharp end portion or an opening portion by a through hole inside the electrode. . Thereby, an electric field concentration part can increase further, and it becomes possible to obtain a more suitable electrode shape.

  Here, a method for manufacturing the electron-emitting device of the present invention having the above-described configuration will be described with examples.

  As the dielectric constituting the emitter section 12, a dielectric having a relatively high relative dielectric constant, for example, 1000 or more can be used. In addition to barium titanate, such dielectrics include lead zirconate, lead magnesium niobate, lead nickel niobate, lead zinc niobate, lead manganese niobate, lead magnesium tantalate, lead nickel tantalate, antimony Ceramics containing lead stannate, lead titanate, lead magnesium tungstate, lead cobalt niobate, etc., or any combination thereof, those containing 50% by weight or more of these compounds as the main component, On the other hand, oxides such as lanthanum, calcium, strontium, molybdenum, tungsten, barium, niobium, zinc, nickel, manganese, etc., or any combination thereof, or those appropriately added with other compounds, etc. Can do.

  For example, in a two-component system nPMN-mPT of lead magnesium niobate (PMN) and lead titanate (PT) (where n and m are mole ratios), increasing the PMN mole ratio decreases the Curie point. Thus, the relative dielectric constant at room temperature can be increased.

  In particular, when n = 0.85 to 1.0 and m = 1.0−n, the relative dielectric constant is preferably 3000 or more. For example, when n = 0.91 and m = 0.09, a room temperature relative permittivity of 15000 is obtained, and when n = 0.95 and m = 0.05, a room temperature relative permittivity of 20000 is obtained.

  Next, in the three-component system of lead magnesium niobate (PMN), lead titanate (PT), and lead zirconate (PZ), besides increasing the mole ratio of PMN, tetragonal and pseudocubic or tetragonal crystals And a composition in the vicinity of a morphotropic phase boundary (MPB) of rhombohedral crystals are preferable for increasing the relative dielectric constant. For example, the relative dielectric constant is 5500 when PMN: PT: PZ = 0.375: 0.375: 0.25, and the relative dielectric constant is 4500 when PMN: PT: PZ = 0.5: 0.375: 0.125. Is particularly preferred. Furthermore, it is preferable to improve the dielectric constant by mixing a metal such as platinum into these dielectrics within a range in which insulation can be ensured. In this case, for example, 20% by weight of platinum may be mixed in the dielectric.

  Further, as described above, a piezoelectric / electrostrictive layer, an antiferroelectric layer, or the like can be used for the emitter section 12. However, when a piezoelectric / electrostrictive layer is used as the emitter section 12, the piezoelectric / electrostrictive layer is used. For example, lead zirconate, lead magnesium niobate, lead nickel niobate, lead zinc niobate, lead manganese niobate, lead magnesium tantalate, lead nickel tantalate, lead antimony stannate, lead titanate, titanate Ceramics containing barium, lead magnesium tungstate, lead cobalt niobate, etc., or any combination thereof may be mentioned.

  It goes without saying that the main component may contain 50% by weight or more of these compounds. Among the ceramics, a ceramic containing lead zirconate is most frequently used as a constituent material of the piezoelectric / electrostrictive layer constituting the emitter section 12.

  Further, when the piezoelectric / electrostrictive layer is composed of ceramics, the ceramics may further include oxides such as lanthanum, calcium, strontium, molybdenum, tungsten, barium, niobium, zinc, nickel, manganese, or any of these. A combination of the above or other compounds as appropriate may be used. Further, a ceramic obtained by adding SiO2, CeO2, Pb5Ge3O11 or any combination thereof to the ceramic may be used. Specifically, a material obtained by adding 0.2 wt% of SiO2 or 0.1 wt% of CeO2 or 1 to 2 wt% of Pb5Ge3 O11 to a PT-PZ-PMN piezoelectric material is preferable.

  For example, it is preferable to use ceramics containing as a main component a component composed of lead magnesium niobate, lead zirconate and lead titanate, and further containing lanthanum or strontium.

  The piezoelectric / electrostrictive layer may be dense or porous, and in the case of being porous, the porosity is preferably 40% or less.

  When an antiferroelectric layer is used as the emitter section 12, the antiferroelectric layer is mainly composed of lead zirconate, a component composed of lead zirconate and lead stannate, Furthermore, what added lanthanum oxide to lead zirconate, and what added lead zirconate and lead niobate to the component which consists of lead zirconate and lead stannate are desirable.

  The antiferroelectric layer may be porous, and in the case of being porous, the porosity is preferably 30% or less.

  Further, when strontium tantalate bistrontate (SrBi2Ta2O9) is used for the emitter section 12, it is preferable that the polarization reversal fatigue is small. Such a material with small polarization reversal fatigue is a layered ferroelectric compound and is represented by the general formula (BiO2) 2+ (Am-1BmO3m + 1) 2-. Here, the ions of metal A are Ca2 +, Sr2 +, Ba2 +, Pb2 +, Bi3 +, La3 +, and the like, and the ions of metal B are Ti4 +, Ta5 +, Nb5 +, and the like. Furthermore, it is possible to make semiconductors by adding additives to barium titanate, lead zirconate, and PZT piezoelectric ceramics. In this case, the electric field concentration can be performed in the vicinity of the interface with the upper electrode 14 that contributes to electron emission by providing an uneven electric field distribution in the emitter section 12.

  In addition, the sintering temperature can be lowered by mixing the piezoelectric / electrostrictive / antiferroelectric ceramics with a glass component such as lead borosilicate glass and other low melting point compounds (such as bismuth oxide).

  In the case of being composed of piezoelectric / electrostrictive / antiferroelectric ceramics, the shape thereof is a sheet-like molded body, a sheet-like laminated body, or a laminate or adhesion of these to another supporting substrate. Also good.

  In addition, by using a lead-free material for the emitter section 12 and making the emitter section 12 a material having a high melting point or transpiration temperature, it becomes difficult to be damaged by collision of electrons or ions.

  As a method for forming the emitter section 12, various thick film forming methods such as a screen printing method, a dipping method, a coating method, an electrophoresis method, an aerosol deposition method, an ion beam method, a sputtering method, a vacuum evaporation method, Various thin film forming methods such as ion plating, chemical vapor deposition (CVD), and plating can be used. In particular, it is preferable to employ a method in which a powdered piezoelectric / electrostrictive material is formed as the emitter section 12 and impregnated with glass or sol particles having a low melting point. This technique enables film formation at a low temperature of 700 ° C. or 600 ° C. or lower.

  As the conductive particles 15 constituting the upper electrode 14 of the present embodiment, scale-like powders such as scale-like graphite powder and metal powder, and needle-like or rod-like powders such as carbon nanotubes are preferably used. As a method for forming the upper electrode 14, a paste is prepared by dispersing the above scaly powder in an organic solvent (binder) such as ethyl cellulose (using a dispersant if necessary), and using this paste. A method of forming a thick film of the paste on the upper surface of the emitter section 12 by spin coating, screen printing, dipping, spray coating, or the like, and heat-treating the paste formed with the thick film can be used. When forming a thick film, when the paste viscosity is about 100,000 to 200,000 cp suitable for the above thick film formation, the film thickness after printing is preferably about 1 μm to 25 μm, more preferably about 3 to 15 μm. . If the film thickness is too thick, the size of the opening 20 becomes too small. Conversely, if the film thickness is too thin, conduction in one upper electrode 14 cannot be ensured. Then, after forming a thick film with a thickness in the above range, a heat treatment is performed so that the formed film on the emitter portion 12 to be the upper electrode 14 becomes only the electrode material together with the decomposition of the binder, and a plurality of The openings 20 are formed, and as a result, a plurality of openings 20 and flanges 26 are formed in the upper electrode 14 as shown in FIG. 1 and the like without performing any special patterning process such as a masking process. Is done. Here, the atmosphere during firing is preferably an inert gas atmosphere such as nitrogen (especially when a carbon-based material is used), but if the blending ratio of the conductive particles 15 in the paste is appropriately adjusted. It is also possible in the air or other oxygen atmosphere (including under reduced pressure).

  When forming the upper electrode 14, as described above, the conductive fine particles 19 are also preferably added. As the conductive fine particles 19, carbon-based fine particles such as spheroidized graphite powder and carbon black can be used in addition to metal fine particles. When the conductive fine particles 19 are added, metal fine particles classified to a predetermined particle diameter can be used, and those that can finally become conductive fine particles by firing can be used. For example, resinate or the like may be used.

  When a carbon-based material is used as the conductive particles 15 (particularly in the air or other oxygen atmosphere), the temperature when the upper electrode 14 is heat-treated is preferably 500 degrees or less, and the conductive fine particles 19 are added. In this case, it is necessary to select a temperature at which the conductive fine particles 19 do not aggregate or grow beyond a predetermined particle size.

  On the other hand, the lower electrode 16 is made of a conductive material such as metal, and is made of platinum, molybdenum, tungsten, or the like. Also, a conductor having resistance to a high-temperature oxidizing atmosphere, such as a simple metal, an alloy, a mixture of insulating ceramics and a simple metal, a mixture of insulating ceramics and an alloy, etc., preferably platinum, iridium, It is composed of a high melting point noble metal such as palladium, rhodium or molybdenum, an alloy containing silver-palladium, silver-platinum or platinum-palladium as a main component, or a cermet material of platinum and a ceramic material. More preferably, it is made of a material mainly composed of platinum or a platinum-based alloy. Further, the lower electrode 16 may be made of carbon or graphite material. In addition, about 5-30 volume% is suitable for the ratio of the ceramic material added in electrode material. Of course, you may make it use the material similar to the upper electrode mentioned above. And when forming the lower electrode 16 with the above-mentioned metal or carbonaceous material, the said thick film formation method is used suitably.

  The electron-emitting devices 10 </ b> A to 10 </ b> C can be integrated with each other by performing heat treatment (firing treatment) each time the emitter section 12, the upper electrode 14, and the lower electrode 16 are formed. In addition, when the upper electrode 14 and the lower electrode 16 are baked, adhesion with the emitter section 12 can be improved by using glass, synthetic resin, or the like (as a binder) if necessary. The temperature related to the baking treatment for integrating the emitter section 12 and the lower electrode 16 may be in the range of 500 to 1400 ° C., preferably in the range of 1000 to 1400 ° C. Further, when the film-shaped emitter section 12 is heat-treated, it is preferable to perform a baking process while controlling the atmosphere together with the evaporation source of the emitter section 12 so that the composition of the emitter section 12 does not become unstable at high temperatures.

  A method may be employed in which the emitter portion 12 is covered with an appropriate member and fired so that the surface of the emitter portion 12 is not directly exposed to the firing atmosphere.

  Next, a preferred embodiment of the method for manufacturing the electron-emitting device according to the present invention, particularly the method for forming the upper electrode 14 will be described.

  In the present embodiment, scale-like graphite particles are used as the conductive particles 15 and silver fine particles are added as the conductive fine particles 19.

  When the upper electrode 14 is formed, the scaly graphite powder particles and the binder are mixed (using a dispersant if necessary), and Ag resinate or Ag ink is further added thereto to obtain a paste. Then, this paste is applied onto the dielectric material to be the emitter section 12 and heat-treated.

  The ratio of graphite to binder is preferably in the range of graphite: binder = 1: 2 to 2: 1. The binder is preferably a synthetic resin that decomposes at 400 ° C. or lower. The compounding ratio of the silver fine particles is a volume ratio of graphite and silver, and the range of graphite: silver = 5: 5 to 9.5: 0.5 is applicable, and 7: 3 to 9: 1 is preferable. In the case of using Ag ink, the particle diameter of silver fine particles dispersed in the ink is preferably 1 μm or less, and more preferably 0.5 μm or less. When the particle diameter of the silver fine particles is larger than the above range, pretreatment such as pulverization and pulverization is performed.

The heat treatment is preferably performed at 450 ° C. or less, more preferably about 400 ° C. so that the silver fine particles do not become coarser than the above range. In addition, since the graphite particles are eroded because the oxidation of carbon is promoted in the presence of silver particles, the atmosphere during heating and firing is slightly more in the atmosphere containing oxygen than in the nitrogen atmosphere. It is possible to increase the amount of graphite.
(Example 1)

  Scale-like graphite powder (trade name “SP20” manufactured by Nippon Graphite Industries Co., Ltd. (average particle size 15 μm, thickness of about 2 μm)) 10 parts by weight, dispersant (Disperbyk-108 manufactured by Big Chemie, Germany) 1 part by weight, A mixture of ethyl cellulose and 2-ethylhexanol at a ratio of 25:75) 25 parts by weight were mixed in a three-roll mill. In addition, when the graphite powder is agglomerated, it is necessary to crush using a homogenizer etc. as a pretreatment.

  Next, Ag resinate (trade name XE109-4 manufactured by NAMICS Co., Ltd.) is added to the above mixture so that the volume ratio of graphite and silver is 9: 1, and the mixture is mixed in a three-roll mill, and the paste is added. Obtained.

And by diluting this paste with terpineol, the viscosity was adjusted to about 100,000 to 200,000 cp, and 15 μm was applied on the dielectric by screen printing. Then, after raising the temperature to 400 ° C. in 15 minutes in a heating furnace, heating in an air atmosphere (atmospheric pressure) for about 2 hours at 400 ° C., and gradually cooling in the furnace, on the dielectric, The electrode was formed with such a thickness that the scale-like graphite layer was about several layers. When this electrode was observed with an electron microscope, formation of an opening of about several to 10 μm was confirmed.
(Example 2)

  Except for using scaly graphite powder (trade name “KS25” (average particle size 25 μm, thickness of about 2 μm) manufactured by TIMCAL) and Ag ink, the same as Example 1 above. Ag ink is an ink in which fine particles of silver are dispersed in a dispersion medium, and 5 parts by weight of a product name “NPS-J” (average particle diameter of about 7 nm) manufactured by Harima Kasei Co., Ltd., polyvinyl butyral (Sekisui) Chemicals Co., Ltd. ESREC B BL-S) 10 parts by weight and 10 parts by weight of terpineol were mixed, and the compounding ratio was the same as in Example 1. Also in this Example 2, the formation of an opening of about several to 10 μm was confirmed, as in Example 1 above.

  It should be noted that the electron-emitting device according to the present invention is not limited to the above-described embodiment, and it goes without saying that various configurations can be adopted as long as the essential part of the present invention is not changed.

  For example, the shape of the opening 20 that becomes the electric field concentration portion at the inner edge may be various shapes as shown in FIGS. 12 to 15 in addition to the shapes described in the above embodiments. .

  In addition, as shown in FIG. 15, the floating electrode 50 may be present in a portion corresponding to the opening 20 in the upper surface 12 a of the emitter 12.

  Furthermore, in the manufacturing method of the above-described embodiment, the opening 20 of the upper electrode 14 is formed simply by forming a thick film by controlling the viscosity, blending ratio, and film thickness of the paste without using special masking or the like. However, as shown in FIG. 17, it may be formed using masking or the like so that the holes 32 having a specific shape are formed. In this case, when viewed microscopically, the hole 32 has an irregular shape due to the influence of the shape of the conductive particles 15, and an effect of increasing the number of electron supply points to the emitter section 12 can be achieved. .

It is sectional drawing which abbreviate | omits and shows the electron emission element which concerns on 1st Embodiment. It is sectional drawing which expands and shows the principal part of the said electron-emitting element. It is a top view which shows an example of the shape of the opening part formed in the upper electrode. It is a figure which shows the voltage waveform of the drive voltage applied to the said electron emitting element. It is explanatory drawing which shows the mode of operation | movement of the said electron emission element. It is explanatory drawing which shows the mode of operation | movement of the said electron emission element. It is an equivalent circuit diagram for demonstrating the influence which the electric field between an upper electrode and a lower electrode receives by gap formation between an upper electrode and an emitter part. It is an equivalent circuit diagram for demonstrating the influence which the electric field between an upper electrode and a lower electrode receives by gap formation between an upper electrode and an emitter part. It is a block diagram which shows the outline of the display to which the said electron emission element is applied. It is sectional drawing which abbreviate | omits and shows the electron emission element which concerns on 2nd Embodiment. It is sectional drawing which abbreviate | omits and shows the electron emission element which concerns on 3rd Embodiment. It is a figure which shows the modification of the cross-sectional shape of the collar part of the upper electrode in the electron emission element which concerns on the 1st-3rd embodiment. It is a figure which shows the further another modification of the cross-sectional shape of the collar part of an upper electrode. It is a figure which shows the further another modification of the cross-sectional shape of the collar part of an upper electrode. It is a figure which shows the further another modification of the cross-sectional shape of the collar part of an upper electrode. It is a figure which shows the modification which provided the float electrode in the electron emission element which concerns on the 1st-3rd embodiment. It is a figure which shows the modification of the opening part shape in the electron emission element which concerns on the 1st-3rd embodiment. It is sectional drawing which abbreviate | omits and shows the conventional electron emission element partially.

Explanation of symbols

10A, 10B, 10C ... Electron-emitting devices, 12 ... Emitter, 12a ... Upper surface, 14 ... Upper electrode, 15 ... Conductive particle, 16 ... Lower electrode, 19 ... Conductive fine particle, 20 ... Opening part, 26 ... Gutter part 26b ... inner edge 28 ... gap 100 ... display

Claims (8)

An emitter portion made of a dielectric, a first electrode formed on the first surface of the emitter portion and having an opening, and a second electrode formed on the second surface of the emitter portion; And an electron-emitting device configured to emit electrons from the emitter through the opening by applying a driving voltage between the first electrode and the second electrode. And
An aggregate of a plurality of conductive particles having a longitudinal direction in a side sectional view and arranged on the first surface of the emitter portion so that the longitudinal direction is along the first surface The first electrode is configured by
The electron-emitting device, wherein the opening is configured by an outer edge of a plurality of the conductive particles. The electron-emitting device according to claim 1 ,
The emitter portion is made of a polycrystalline body,
The first electrode is formed by arranging a plurality of primary particles of the conductive particles and / or secondary particles in which the primary particles are collected on the first surface of the emitter part,
An electron-emitting device, wherein a length in a longitudinal direction of the primary particles or secondary particles in a side sectional view is longer than an average particle diameter of crystal grains of the polycrystal. The electron-emitting device according to claim 1 or 2 ,
The electron-emitting device, wherein the first electrode is made of graphite. The electron-emitting device according to any one of claims 1 to 3 ,
The first electrode further includes conductive fine particles. The electron-emitting device according to claim 4 .
The electron-emitting device according to claim 1, wherein the fine particles are also attached to the first surface of the emitter portion corresponding to the opening. The electron-emitting device according to claim 4 or 5 ,
An electron-emitting device, wherein the fine particles are made of silver. An emitter portion made of a dielectric, a first electrode formed on the first surface of the emitter portion and having an opening, and a second electrode formed on the second surface of the emitter portion. And an electron-emitting device configured to emit electrons from the emitter through the opening by applying a driving voltage between the first electrode and the second electrode. An electron-emitting device manufacturing method for
Preparing a paste in which conductive particles having a longitudinal direction in a side sectional view are dispersed in a dispersion medium;
Forming a film of the paste on the first surface of the emitter section;
The method of manufacturing an electron-emitting device, wherein the first electrode is formed by heating the film. In the manufacturing method of the electron-emitting device according to claim 7 ,
A method for manufacturing an electron-emitting device, wherein when preparing the paste, conductive fine particles are dispersed in the dispersion medium.

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