JP4810010B2 - Electron emitter - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electron-emitting device, and further relates to an electron source and an image forming apparatus using the electron-emitting device.
[0002]
[Prior art]
Conventionally, two types of electron-emitting devices are known: a thermionic source and a cold cathode electron source. Cold cathode electron sources include a field emission type (hereinafter referred to as FE type), a metal / insulating layer / metal type (hereinafter referred to as MIM type), a surface conduction electron-emitting device, and the like.
[0003]
As an example of the FE type, W.W. P. Dyke & W. W. Dolan, “Field Emission”, Advance in Electron Physics, 8, 89 (1956) or C.I. A. Spindt, “PHYSICAL Properties of thin-film field emissions with molecular denies”, J. Am. Appl. Phys. 47, 5248 (1976), etc. are known.
[0004]
Examples of the MIM type include C.I. A. Mead, “Operation of Tunnel-Emission Devices”, J. Am. Apply. Phys. , 32, 646 (1961), etc. are known.
[0005]
In a recent example, Toshiaki. Kusunoki, “Fluctuation-free electro emission from non-formed metal-insulator-metal (MIM) cathodes Fabricated by current Anodization.” J. et al. Appl. Phys. vol. 32 (1993) p. L1695, Mutsumi suzuki et al., “An MIM-Cathode Array for Cathode Luminescent Displays”, IDW '96, (1996) pp. 199 529 etc. have been studied.
[0006]
Examples of the surface conduction type include those described in Elinson's report (MI Elinson Radio Eng. Electron Phys., 10 (1965)). This surface conduction type electron-emitting device is formed on a substrate. A phenomenon is caused in which electron emission is caused by flowing a current through the small-area thin film in parallel with the film surface. In the surface conduction type device, the SnO described in the above-mentioned Erinson report ₂ Thin film, Au thin film (G. Dittmer. Thin Solid Films, 9, 317 (1972)), In ₂ O _Three / SnO ₂ A thin film (M. Hartwell and C. G. Fonstad, IEEE Trans. ED Conf., 519 (1983)) has been reported.
[0007]
[Problems to be solved by the invention]
Here, in order to apply the electron-emitting device to the image forming apparatus, an emission current that causes the phosphor to emit light with sufficient luminance is required. Further, in order to increase the definition of the display, it is required that the diameter of the electron beam irradiated to the phosphor is small. And it is important that it is easy to manufacture.
[0008]
The conventional MIM type has a structure in which an insulator is disposed between a lower electrode and an upper electrode, and a voltage is applied between both electrodes to extract electrons. The direction of the internal electric field coincides with the direction of the emitted electrons, and the potential distribution on the emission surface is not distorted, so that a small electron beam diameter can be realized, but the electron scattering occurs between the insulating layer and the upper electrode. In general, the efficiency is low.
[0009]
As an example of a conventional FE type, there is a Spindt type electron-emitting device. In the Spindt type, a structure in which a microchip is formed as an emission point and electrons are emitted from the tip is generally used. When the emission current density is increased in order to make the phosphor emit light, the electron emission portion is thermally destroyed. This will limit the life of the FE element. Further, electrons emitted from the tip tend to spread due to the electric field formed by the gate electrode, and there is a disadvantage that the beam diameter cannot be reduced.
[0010]
As an example of preventing the spread of the electron beam, there is an example in which a focusing electrode is disposed above the electron emission portion. In general, the emitted electron beam is focused by the negative potential of the focusing electrode. However, the manufacturing process becomes complicated and the manufacturing cost increases.
[0011]
Further, in the Spindt type, since one point at the tip of the microchip serves as an electron emission point, it is common to increase the electron emission point by using a plurality of electron emission parts in one element to secure a necessary amount of electron emission. . Further, by increasing the electron emission point, the fluctuation of the electron emission amount can be reduced and the stability is improved.
[0012]
However, when there are a plurality of electron emission portions in one element, the diameter of the entire electron beam depends on the position of the outermost electron emission portion and is generally larger than that in the case of one electron emission portion.
[0013]
As a solution to such a problem, there are those disclosed in US Pat. No. 5,528,103 and Japanese Patent Application Laid-Open No. 2000-106112 as examples having a function of bending an electron beam around one element. These have the disadvantage that the area of one element has to be increased in order to effectively control the electron beam, and are insufficient for a high-definition electron beam.
[0014]
On the other hand, if the direction of the electron beam can be deflected independently within one element, an element having a plurality of electron emission portions can be constructed without increasing the electron beam diameter.
[0015]
As a conventional example of such a conventional FE type Spindt type, there is one disclosed in Japanese Patent Application Laid-Open No. 8-315721, which is shown in FIG. In FIG. 15, 131 is a substrate, 132 is a conical cathode, 133 is a cavity, 134 is an insulating layer, and 135 is a gate electrode. The conical cathode is arranged eccentrically. ,
As another example of reducing the electron beam diameter, there is a method that does not form a Spindt type microchip. For example, there are those disclosed in JP-A-8-096703 and JP-A-8-096704. This has the advantage that a flat equipotential surface is formed on the electron emission surface and the spread of the electron beam is reduced because electrons are emitted from the thin film disposed in the hole.
[0016]
In addition, by using a material having a low work function as the electron-emitting substance, electrons can be emitted without forming a microchip, and a low driving voltage can be achieved. There is also an advantage that the manufacturing method is relatively simple.
[0017]
Further, since the electron emission is performed in a planar shape, the electric field is not concentrated, the chip is not broken, and the life is long.
[0018]
Such a structure has an advantage that the electron beam from the electron-emitting device from each minute hole can be made small.
[0019]
However, in the fine hole, the area of the electron emission portion is small, and the amount of electron emission is reduced with only one electron emission portion.
[0020]
The present invention has been made in order to solve the above-described problems of the prior art, and an object thereof is to provide an electron-emitting device that realizes further reduction in the electron beam diameter, and the electron-emitting device. An object is to provide a high-definition electron source and an image forming apparatus with good image quality.
[0028]
A cathode electrode disposed on the surface of the substrate; and a gate electrode stacked on the cathode electrode with an insulating layer interposed therebetween, wherein the partial region of the cathode electrode passes through the insulating layer and the gate electrode. In an electron-emitting device in which a plurality of openings that expose the substrate are provided, and an electron-emitting layer that is electrically connected to the cathode electrode is provided in each of the openings. The shape when the opening is viewed from a direction perpendicular to the surface of the substrate is a ring shape, The plurality of openings are a plurality of openings arranged in a central portion of the electron-emitting device, and a plurality of openings in a peripheral portion arranged so as to surround the plurality of openings in the central portion. The opening in the central part is formed to have the same height side wall, and the opening in the peripheral part is an electron emitted from the electron emission layer in the opening in the peripheral part. In order to change the beam toward the central portion, the side wall on the side opposite to the central portion is formed to be higher than the side wall on the central portion side.
[0031]
The opening When viewed from a direction perpendicular to the surface of the substrate The ring shape Is It is also suitable.
[0032]
A connecting portion for connecting the inner gate electrode and the outer gate electrode of the ring-shaped opening is provided. It is also suitable.
[0039]
DETAILED DESCRIPTION OF THE INVENTION
Exemplary embodiments of the present invention will be described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent. Further, the conditions such as the voltage applied to the cathode, the gate, and the anode electrode, the driving waveform, and the like are not limited to those unless otherwise specified.
[0040]
1 to 4 are schematic views of an electron-emitting device according to an embodiment of the present invention.
[0041]
In FIG. 1, the top view of the element in xy plane is shown. For convenience of explanation, the drawing is hatched for each member. FIG. 2 shows a driving state of the element in FIG. 1, and shows a cross-section AA ′ in FIG. 1 in a perspective view.
[0042]
The electron-emitting device according to the present embodiment is roughly laminated on the substrate 1, the cathode electrode 2 laminated on the substrate 1, the insulating layer 3 laminated on the cathode electrode 2, and the insulating layer 3. The first and second gate electrodes 4 a and 4 b and the electron emission layer 5 are configured.
[0043]
The electron emission layer 5 is formed in a slit-shaped opening having a width of w1 and a length of L1, and is electrically connected to the cathode electrode 2. The opening is a part of the insulating layer 3 and the gate electrodes 4a and 4b removed.
[0044]
Further, a plurality of slit-like openings are formed in the x direction, here three in the x direction, and the slits are provided adjacent to each other by w2.
[0045]
In the present embodiment, the electron emission structure is a structure that has a slit-like opening and an electron emission layer 5 formed in the opening, and emits electrons from the electron emission layer 5. A plurality of the electron-emitting devices are provided.
[0046]
As a deflection emission structure, a second gate 4b is further laminated on the first gate electrode 4a on both sides of the element.
[0047]
That is, in the central region of the plurality of electron emission structures, the side wall that forms the opening and is laminated by at least the insulating layer 3 and the first gate electrode 4a is provided at substantially the same height. In the other regions, the region where the second gate 4b is stacked is a region in which the height of the side wall constituting the opening is partially different.
[0048]
Therefore, in this element, the electron emission portion as the electron emission structure in the central region composed of the opening portion having the same height and the electron emission portion in the periphery (region other than the central region) composed of the opening portion having a different height of the gate electrode. And is composed of.
[0049]
Here, the deflection emission structure is provided independently of the electron emission structure existing in the central region, and the height of the side wall located on the central region side among the side walls of the opening of the deflection emission structure. Is provided lower than the height of the side wall located on the side away from the central region, and has an asymmetric structure.
[0050]
A driving voltage Vg is applied by the power source 6 between the cathode electrode 2 and the gate electrodes 4a and 4b.
[0051]
Reference numeral 7 denotes an anode electrode disposed above the electron-emitting device, and an anode voltage Va is applied by the high-voltage power supply 8. The distance H between the anode electrode and the element is usually determined based on the position of the cathode electrode 2. The anode 7 captures electrons from the electron emission portion.
[0052]
FIG. 3 is a diagram for explaining the relationship between the equipotential surface of the element of FIG. 2 and the electron beam trajectory.
[0053]
Since the equipotential surface almost symmetric with respect to the opening is directly above the electron emission portion in the central region, electrons are emitted vertically toward the z direction, and the spread is symmetrical with respect to the x direction. Become.
[0054]
On the other hand, in the peripheral electron emission portion, the equipotential surface is also asymmetric due to the asymmetry of the height of the gate electrode. As a result, the electron trajectory is bent. It is the trajectory on the side where the second gate electrode 4b is laminated, that is, the periphery of the element, that is affected. Therefore, the spread of the electron emission portion in the peripheral portion is asymmetric with respect to the x direction. By providing an appropriate asymmetry, the spread of the electron emission portion in the peripheral portion as shown in FIG. 3 can be exactly overlapped with the spread in the central region.
[0055]
In the electron-emitting device of this embodiment, the opening is made fine and the electron-emitting layer 5 is configured to be substantially flat, so that there is relatively little distortion between the electron-emitting layer 5 and the anode electrode 7. Since a flat electric field is formed, the spread of the electron beam is relatively small.
[0056]
Further, by selecting a material having a low work function as the material of the electron emission layer 5, the element driving voltage can be lowered.
[0057]
Furthermore, there are three electron emission portions, and the amount of electron emission can be increased as compared with one electron emission portion, and fluctuations in electron emission are reduced.
[0058]
Furthermore, the electron emission position of the electron emission part in the central region and the electron emission part in the peripheral part can be brought close to each other, and the spread of the beam diameter can be suppressed even if there are a plurality of electron emission parts.
[0059]
FIG. 4 is a diagram for explaining an example of a method for manufacturing the electron-emitting device of the present embodiment shown in FIG.
[0060]
Hereinafter, an example of a method for manufacturing the electron-emitting device of the present embodiment will be described with reference to FIG.
[0061]
As shown in FIG. 4 (a), the surface is sufficiently cleaned beforehand, and quartz glass, glass with reduced impurity content such as Na, blue plate glass, silicon substrate or the like is sputtered to form SiO. ₂ 1 is used as the substrate 1, and the cathode electrode 2 is stacked on the substrate 1.
[0062]
The cathode electrode 2 generally has conductivity, and is formed by a general vacuum film forming technique such as a vapor deposition method or a sputtering method, or a photolithography technique. The material of the cathode electrode 2 is, for example, a metal or alloy material such as Be, Mg, Ti, Zr, Hf, V, Nb, Ta, Mo, W, Al, Cu, Ni, Cr, Au, Pt, Pd, or TiC. , ZrC, HfC, TaC, SiC, WC and other carbides, HfB ₂ , ZrB ₂ , LaB ₆ , CeB ₆ , YB _Four , GdB _Four Boron such as TiN, nitrides such as TiN, ZrN, and HfN, semiconductors such as Si and Ge, organic polymer materials, amorphous carbon, graphite, diamond-like carbon, carbon in which diamond is dispersed, and carbon compounds are appropriately selected. . The thickness of the cathode electrode 2 is set in the range of several tens of nm to several mm, and is preferably selected in the range of several hundreds of nm to several μm.
[0063]
Next, the insulating layer 3 and the first gate electrode 4 a are deposited following the cathode electrode 2.
[0064]
The insulating layer 3 is formed by a general vacuum film forming method such as a sputtering method, a CVD method, or a vacuum evaporation method, and the thickness is set in the range of several nm to several μm, preferably from several tens of nm. It is selected from the range of several hundred nm. Desirable material is SiO ₂ , SiN, Al ₂ O _Three A material having a high withstand voltage that can withstand a high electric field, such as CaF, is desirable.
[0065]
The first gate electrode 4a has conductivity like the cathode electrode 2, and is formed by a general vacuum film forming technique such as a vapor deposition method or a sputtering method, or a photolithography technique. The material of the first gate electrode 4a is, for example, a metal or alloy such as Be, Mg, Ti, Zr, Hf, V, Nb, Ta, Mo, W, Al, Cu, Ni, Cr, Au, Pt, or Pd. Materials, carbides such as TiC, ZrC, HfC, TaC, SiC, WC, HfB ₂ , ZrB ₂ , LaB ₆ , CeB ₆ , YB _Four , GdB _Four It is appropriately selected from borides such as TiN, nitrides such as ZrN and HfN, semiconductors such as Si and Ge, and organic polymer materials.
[0066]
Next, as shown in FIG. 4B, a second gate electrode 4b is partially fabricated.
[0067]
Note that the second gate electrode 4b may be made of the same material or a different material as the first gate electrode 4a, and may be formed by the same method or a different method.
[0068]
Next, as shown in FIG. 4C, a mask pattern 41 is formed by photolithography.
[0069]
Further, an opening is formed as shown in FIG. The opening is a part of the insulating layer 3, the first gate electrode 4 a, and the second gate electrode 4 b that is partially removed from the cathode electrode 2. However, this etching process may be stopped on the cathode electrode 2 or a part of the cathode electrode 2 may be etched.
[0070]
However, it must be avoided that the cathode electrode 2 itself reflects the step shape of FIG.
[0071]
Therefore, it is necessary to select an etching method according to the material of each layer of the cathode electrode 2, the insulating layer 3, and the gate electrode 4, respectively.
[0072]
Next, as shown in FIG. 4E, the electron emission layer 5 is deposited on the entire surface.
[0073]
The electron emission layer 5 is formed by a general film forming technique such as vapor deposition, sputtering, or plasma CVD. The material of the electron emission layer 5 is preferably selected from a material having a low work function. For example, it is appropriately selected from amorphous carbon, graphite, diamond-like carbon, carbon in which diamond is dispersed, and a carbon compound. A diamond thin film or diamond-like carbon having a lower work function is preferable. The film thickness of the electron emission layer 5 is set in the range of several nm to several hundred nm, and is preferably selected in the range of several nm to several tens of nm.
[0074]
If the electric field required for emitting electrons from these electron emission layers 5 can be made as low as possible, the drive voltage can be reduced. ~ 5x10 ^Five If it is V / m or less, the drive voltage can be reduced to about several tens of volts, which is preferable.
[0075]
Next, as shown in FIG. 4F, the mask pattern 41 is peeled off to complete the element as shown in FIG.
[0076]
The difference in height of the gate electrode 4b is set in the range of several tens of nanometers to several tens of micrometers, preferably about several hundreds of nanometers, and the asymmetry condition is selected according to the beam diameter.
[0077]
In this case, the beam diameter in the asymmetrical direction, that is, the x direction is reduced.
[0078]
The hole diameter w1 is a factor that greatly depends on the electron emission characteristics of the device, and the characteristics of the material constituting the device, particularly the work function and film thickness of the electron emission layer, the drive voltage of the device, and the electron emission required at that time It is set appropriately depending on the shape of the beam. Usually, w1 is selected from the range of several hundred nm to several tens of μm.
[0079]
The planar shape of the hole is not particularly defined. However, as a preferable configuration for forming asymmetry, a slit shape, a ring shape, or the like is preferable.
[0080]
When the holes are fine or ring-shaped, the interval w2 between the holes is also important, but usually w2 is appropriately selected from the range of several hundred nm to several tens of μm.
[0081]
The length L1 of the hole is a factor that depends on the amount of electron emission, and is appropriately set.
[0082]
Furthermore, after patterning of the cathode electrode 2, the electron emission layer 5 may be formed on the entire surface, and the etching may be stopped on the upper surface of the electron emission layer 5 in the etching step, and a diamond thin film or diamond-like carbon may be used. In some cases, it is selectively deposited at a desired location.
[0083]
Furthermore, the electron-emitting device of this embodiment has a very simple configuration in which lamination is repeated, the manufacturing process is easy, and the electron-emitting device can be manufactured with a high yield.
[0084]
Application examples of the electron-emitting device to which the present invention is applied will be described below.
[0085]
For example, an electron source or an image forming apparatus can be configured by arranging a plurality of electron-emitting devices of this embodiment on a substrate.
[0086]
Various arrangements of the electron-emitting devices are employed. As an example, a plurality of electron-emitting devices are arranged in a matrix in the X and Y directions, and one of the electrodes of the plurality of electron-emitting devices arranged in the same row is commonly connected to the X-direction wiring, and the same column There is a simple matrix arrangement in which the other of the electrodes of the plurality of electron-emitting devices arranged in the Y is connected in common to the wiring in the Y direction.
[0087]
Hereinafter, the simple matrix arrangement will be described in detail.
[0088]
5 and 6, 51 and 61 are electron source substrates, 52 and 62 are X-directional wirings, and 53 and 63 are Y-directional wirings. Reference numerals 54 and 64 denote electron-emitting devices according to the present embodiment.
[0089]
The m X-direction wirings 62 are made of Dx1, Dx2,... Dxm, and can be made of a conductive metal or the like formed using a vacuum deposition method, a printing method, a sputtering method, or the like. The wiring material, film thickness, and width are appropriately designed. The Y-direction wiring 63 includes n wirings Dy1, Dy2,... Dyn, and is formed in the same manner as the X-direction wiring 62. An interlayer insulating layer (not shown) is provided between the m X-direction wirings 62 and the n Y-direction wirings 63 to electrically isolate them (m and n are Both are positive integers).
[0090]
The interlayer insulating layer (not shown) is made of SiO formed by vacuum deposition, printing, sputtering, etc. ₂ Etc. For example, it is formed in a desired shape on the entire surface or a part of the substrate 61 on which the X-direction wiring 62 is formed. The manufacturing method is appropriately set. The X direction wiring 62 and the Y direction wiring 63 are drawn out as external terminals, respectively.
[0091]
The m X-direction wirings 62 constituting the electron-emitting device 64 may also serve as the cathode electrode 2, and the n Y-direction wirings 63 may serve as the gate electrode 4, and the interlayer insulating layer may be the insulating layer 3. There is a case to be able to.
[0092]
The X-direction wiring 62 is connected to scanning signal applying means (not shown) for applying a scanning signal for selecting a row of the electron-emitting devices 64 arranged in the X direction. On the other hand, the Y-direction wiring 63 is connected to modulation signal generating means (not shown) for modulating each column of the electron-emitting devices 64 arranged in the Y direction according to an input signal. The drive voltage applied to each electron-emitting device is supplied as a difference voltage between the scanning signal and the modulation signal applied to the device.
[0093]
In the above configuration, individual elements can be selected and driven independently using a simple matrix wiring. An image forming apparatus configured using such a simple matrix electron source will be described with reference to FIG.
[0094]
FIG. 7 is a schematic diagram illustrating an example of a display panel of the image forming apparatus.
[0095]
In FIG. 7, 71 is an electron-emitting device, 81 is an electron source substrate on which a plurality of electron-emitting devices are arranged, 91 is a rear plate to which the electron source substrate 81 is fixed, 96 is a fluorescent film 94 and a metal back 95 on the inner surface of a glass substrate 93. And so on. Reference numeral 92 denotes a support frame, and a rear plate 91 and a face plate 96 are connected to the support frame 92 using frit glass or the like.
[0096]
The envelope (panel) 98 includes the face plate 96, the support frame 92, and the rear plate 91 as described above. Since the rear plate 91 is provided mainly for the purpose of reinforcing the strength of the substrate 81, if the substrate 81 itself has sufficient strength, the separate rear plate 91 can be omitted, and the substrate 81 and the rear plate 91 can be omitted. May be an integral member.
[0097]
Frit glass is applied to the bonding surface where the face plate 96, the rear plate 91, and the support frame 92 on which the fluorescent film 94 and the metal back 95 of the support frame 92 are arranged on the inner surface thereof, and the face plate 96 and the support frame 92 are applied. And the rear plate 91 are aligned at a predetermined position, fixed, heated, baked and sealed.
[0098]
Further, the heating means for firing and sealing can employ various means such as lamp heating using an infrared lamp or the like, a hot plate, and the like, but is not limited thereto.
[0099]
In addition, the adhesive material that heat-bonds a plurality of members constituting the envelope is not limited to frit glass, and various adhesive materials can be used as long as the material can form a sufficient vacuum atmosphere after the sealing process. can do.
[0100]
The envelope described above is one embodiment of the present invention, and is not limited, and various types can be employed.
[0101]
As another example, the support frame 92 may be directly sealed on the substrate 81, and the envelope 98 may be configured by the face plate 96, the support frame 92, and the substrate 81. In addition, by installing a support body (not shown) called a spacer between the face plate 96 and the rear plate 91, an envelope 98 having sufficient strength against atmospheric pressure can be configured.
[0102]
FIG. 8 is a schematic diagram showing the fluorescent film 94 formed on the face plate 96. In the case of monochrome, the fluorescent film 94 can be composed of only the phosphor 85. In the case of a color fluorescent film, it can be composed of a black conductive material 86 called a black stripe shown in FIG. 8A or a black matrix shown in FIG. .
[0103]
The purpose of providing the black stripe and the black matrix is to make the mixed colors and the like inconspicuous by making the coloration portions between the phosphors 85 of the three primary color phosphors necessary in the case of color display, The purpose is to suppress a decrease in contrast due to light reflection. As a material for the black stripe, in addition to a commonly used material mainly composed of graphite, a material having electrical conductivity and little light transmission and reflection can be used.
[0104]
As a method of applying the phosphor on the glass substrate 93, a precipitation method, a printing method, or the like can be adopted regardless of monochrome or color. A metal back 95 is usually provided on the inner surface side of the fluorescent film 94. The purpose of providing the metal back is to improve the luminance by specularly reflecting the light emitted from the phosphor toward the inner surface to the face plate 96 side, to act as an electrode for applying an electron beam acceleration voltage, For example, the fluorescent film 94 is protected from damage caused by the collision of negative ions generated in the envelope. The metal back 95 can be manufactured by performing a smoothing process (usually called “filming”) on the inner surface of the fluorescent film after manufacturing the fluorescent film, and then depositing Al using vacuum evaporation or the like.
[0105]
The face plate 96 may be provided with a transparent electrode (not shown) on the outer surface side of the fluorescent film 94 in order to further increase the conductivity of the fluorescent film 94.
[0106]
In the present embodiment, since the electron beam reaches directly above the electron-emitting device 71, the fluorescent film 94 is arranged so as to be positioned immediately above the electron-emitting device 71.
[0107]
Next, the vacuum sealing process for sealing the envelope (panel) subjected to the sealing process will be described.
[0108]
In the vacuum sealing process, the envelope (panel) 98 is heated and held at 80 to 250 ° C., and exhausted through an exhaust pipe (not shown) by an exhaust device such as an ion pump or a sorption pump. After the atmosphere is sufficiently low, the exhaust pipe is heated with a burner to dissolve and sealed. In order to maintain the pressure after the envelope 98 is sealed, a getter process may be performed. This is because the getter disposed at a predetermined position (not shown) in the envelope 98 is heated by heating using resistance heating or high-frequency heating immediately before or after sealing the envelope 98. And a process for forming a deposited film. The getter usually has Ba or the like as a main component, and maintains the atmosphere in the envelope 98 by the adsorption action of the deposited film.
[0109]
The image forming apparatus configured by using the electron source having the simple matrix arrangement manufactured by the above process applies the voltage to each electron-emitting device via the external terminals Dox1 to Doxm, Doy1 to Doyn, thereby generating electrons. Release occurs.
[0110]
A high voltage is applied to the metal back 95 or the transparent electrode (not shown) through the high voltage terminal 97 to accelerate the electron beam.
[0111]
The accelerated electrons collide with the fluorescent film 94, light is emitted, and an image is formed.
[0112]
FIG. 9 is a block diagram showing an example of a drive circuit for performing display in accordance with an NTSC television signal.
[0113]
The scanning circuit 1302 includes M switching elements therein (schematically indicated by S1 to Sm in the drawing). Each switching element selects either the output voltage of the DC voltage source Vx or 0 (V) (ground level), and is electrically connected to the terminals Dox1 to Doxm of the display panel 1301.
[0114]
The switching elements S1 to Sm operate based on a control signal Tscan output from the control circuit 1303, and can be configured by combining switching elements such as FETs.
[0115]
The DC voltage source Vx is set based on the characteristics of the electron-emitting device.
[0116]
The control circuit 1303 has a function of matching the operation of each unit so that appropriate display is performed based on an image signal input from the outside. The control circuit 1303 generates Tscan, Tsft, and Tmry control signals for each unit based on the synchronization signal Tsync sent from the synchronization signal separation circuit 1306.
[0117]
The synchronization signal separation circuit 1306 is a circuit for separating a synchronization signal component and a luminance signal component from an NTSC television signal input from the outside, and can be configured using a general frequency separation (filter) circuit or the like. The synchronization signal separated by the synchronization signal separation circuit 1306 includes a vertical synchronization signal and a horizontal synchronization signal, but is illustrated here as a Tsync signal for convenience of explanation. The luminance signal component of the image separated from the television signal is expressed as a DATA signal for convenience. The DATA signal is input to the shift register 1304.
[0118]
The shift register 1304 is for serial / parallel conversion of the DATA signal input serially in time series for each line of the image, and operates based on the control signal Tsft sent from the control circuit 1303. (That is, it can be said that the control signal Tsft is a shift clock of the shift register 1304). Data for one line (corresponding to driving data for N electron-emitting devices) subjected to serial / parallel conversion is output from the shift register 1304 as N parallel signals Id1 to Idn.
[0119]
The line memory 1305 is a storage device for storing data for one line of image for a necessary time, and appropriately stores the contents of Id1 to Idn according to the control signal Tmry sent from the control circuit 1303. The stored contents are output as Id′1 to Id′n and input to the modulation signal generator 1307.
[0120]
The modulation signal generator 1307 is a signal source for appropriately driving and modulating each of the electron-emitting devices according to the present embodiment in accordance with each of the image data Id′1 to Id′n. The voltage is applied to the electron-emitting devices of this embodiment in the display panel 1301 through Doy1 to Doyn.
[0121]
When a pulsed voltage is applied to the device, for example, electron emission does not occur even when a voltage equal to or lower than the electron emission threshold is applied, but when a voltage equal to or higher than the electron emission threshold is applied, an electron beam is output. At that time, the intensity of the output electron beam can be controlled by changing the pulse peak value Vm. Further, it is possible to control the total amount of charges of the output electron beam by changing the pulse width Pw.
[0122]
Therefore, a voltage modulation method, a pulse width modulation method, or the like can be adopted as a method for modulating the electron-emitting device according to the input signal. When implementing the voltage modulation method, a voltage modulation method circuit is used as the modulation signal generator 1307, which generates a voltage pulse of a certain length and appropriately modulates the peak value of the pulse according to the input data. be able to.
[0123]
When implementing the pulse width modulation method, the modulation signal generator 1307 generates a voltage pulse having a constant peak value and modulates the width of the voltage pulse as appropriate according to the input data. A circuit can be used.
[0124]
The shift register 1304 and the line memory 1305 can be digital signal type or analog signal type. This is because the serial / parallel conversion and storage of the image signal may be performed at a predetermined speed.
[0125]
When the digital signal system is used, it is necessary to convert the output signal DATA of the synchronization signal separation circuit 1306 into a digital signal. For this purpose, an A / D converter may be provided at the output unit 1306. In this connection, the circuit used in the modulation signal generator 1307 is slightly different depending on whether the output signal of the line memory 1305 is a digital signal or an analog signal. That is, in the case of a voltage modulation method using a digital signal, for example, a D / A conversion circuit is used as the modulation signal generator 1307, and an amplifier circuit or the like is added as necessary.
[0126]
In the case of the pulse width modulation system, the modulation signal generator 1307 includes, for example, a high-speed oscillator and a counter that counts the wave number output from the oscillator, and a comparator that compares the output value of the counter with the output value of the memory. A circuit combining (comparators) is used. If necessary, an amplifier for amplifying the pulse width-modulated modulation signal output from the comparator up to the driving voltage of the electron-emitting device of this embodiment can be added.
[0127]
In the case of a voltage modulation method using an analog signal, for example, an amplifier circuit using an operational amplifier or the like can be adopted as the modulation signal generator 1307, and a level shift circuit or the like can be added if necessary. In the case of the pulse width modulation method, for example, a voltage-controlled oscillation circuit (VCO) can be adopted, and an amplifier for amplifying the voltage up to the driving voltage of the electron-emitting device of this embodiment can be added as necessary. it can.
[0128]
The configuration of the image forming apparatus described here is an example of an image forming apparatus to which the present invention can be applied, and various modifications can be made based on the technical idea of the present invention. As for the input signal, the NTSC system is mentioned, but the input signal is not limited to this, and other than this, the PAL, SECAM system, and the like, the TV signal (for example, the MUSE system including a number of scanning lines) is included. High-definition TV) can also be adopted.
[0129]
Further, in addition to a display device, the image forming device can be used as an optical printer configured using a photosensitive drum or the like.
[0130]
【Example】
Hereinafter, embodiments of the present invention will be described in detail.
[0131]
[Example 1]
An example of an electron-emitting device and a method for manufacturing the same according to Embodiment 1 of the present invention will be described with reference to FIGS.
[0132]
(Process 1)
First, as shown in FIG. 4 (a), quartz was used for the substrate 1, and after sufficient cleaning, Al having a thickness of 800 nm was formed as the cathode electrode 2 by sputtering.
[0133]
Next, SiO layer having a thickness of 600 nm is formed as the insulating layer 3. ₂ Then, Ta having a thickness of 100 nm was deposited in this order as the gate electrode 4a.
[0134]
(Process 2)
Further, as shown in FIG. 4B, Ta having a thickness of 400 nm was partially formed as a gate electrode 4b through a mask pattern.
[0135]
(Process 3)
Next, as shown in FIG. 4C, a positive photoresist (AZ1500 / manufactured by Clariant) spin coating and photomask pattern were exposed and developed by photolithography to form a mask pattern 41.
[0136]
(Process 4)
4D, using the mask pattern 41 as a mask, the Ta gate electrodes 4a and 4b and the insulating layer 3 are CF. _Four Each gas was dry-etched and stopped at the cathode electrode 2 to form an opening having a width w1 of 1 μm, an interval w2 between adjacent elements of 5 μm, and a width L1 of 100 μm.
[0137]
(Process 5)
Subsequently, as shown in FIG. 4E, a diamond-like carbon electron emission layer 5 was deposited to a thickness of about 100 nm on the entire surface by plasma CVD. Reaction gas is CH _Four Gas was used.
[0138]
(Step 6)
As shown in FIG. 4F, the mask pattern 41 was completely removed, and the electron-emitting device of Example 1 was completed.
[0139]
The electron-emitting device manufactured as described above was arranged with H = 2 mm as shown in FIG. Va = 10 kV and Vg = 15V.
[0140]
Here, as Comparative Example 1, a symmetric element formed by only the first gate electrode without stacking the second gate electrode 4b was manufactured and simultaneously driven.
[0141]
Here, an electrode coated with a phosphor was used as the anode electrode 7, and the size of the electron beam was observed. The electron beam size referred to here is a size up to a region of 10% of the peak luminance in the emitted phosphor.
[0142]
As a result, the amount of electron emission was almost the same in both the comparative example and the example. The beam diameter was (x, y) = (180 μm, 220 μm) in Comparative Example 1, and (120 μm, 220 μm) in this example, and the beam diameter was reduced in the x direction.
[0143]
[Example 2]
FIG. 10 shows a second embodiment of the present invention. The present embodiment is a modification of the first embodiment, and the element in FIG. 10 is a plan view.
[0144]
In this embodiment, the slits are w1 = 1 μm, w2 = 5 μm, L1 = 30 μm, and seven slits are arranged in the x direction and two in the y direction, one in the periphery, and the second gate electrode 4b is arranged. It is formed surrounding the slit. In this embodiment, asymmetry is also formed in the y direction.
[0145]
As a result, the beam diameter was (x, y) = (180 μm, 180 μm), and the beam diameter was reduced in the y direction, resulting in a substantially circular beam.
[0146]
[Example 3]
A third embodiment of the present invention is shown in FIGS. FIG. 11 is a plan view.
[0147]
In this embodiment, the slits of Embodiment 1 are circular, and 5 × 5 electron-emitting portions having a ring-like shape are arranged in one element.
[0148]
As one electron-emitting device, 3 × 3 electron-emitting portions are arranged in the center, and 16 electron-emitting portions are arranged in the peripheral portion so as to surround it.
[0149]
FIG. 12 shows a plan view of a typical electron-emitting device of this example. 12A is a plan view of the central element 111 shown in FIG. 11, and FIG. 12B is a plan view of the peripheral element 112 shown in FIG.
[0150]
Both are configured with a ring hole width w1 and an inner diameter w3.
[0151]
The element in the center is a connection portion formed in a part of the ring, and the gate electrode 4a inside the ring and the gate electrode 4a outside the ring are connected. The connecting portion may have the same configuration as that in the ring or may have a different configuration. The connection direction may be one or more.
Further, the connecting portion may be connected to the lower portion of the cathode electrode 2 and the interlayer insulating layer (not shown) through a contact hole that penetrates the insulating layer 3 and the cathode electrode 2. In this case, it is not necessary to arrange the connection part in a part of the ring.
[0152]
Further, the second gate electrode 4b is not stacked on the element 111 in the central portion.
[0153]
The peripheral element 112 has a connection portion in the same manner as the central element 111, but the connection portion is formed over the entire surface in the direction toward the central portion.
[0154]
A second gate electrode 4b is stacked on the peripheral element 112 on the side facing the peripheral part.
[0155]
A schematic diagram of the electron trajectory in this example is shown in FIG. 13A is a cross-sectional view and an electron trajectory diagram of the element 111 in the central portion, and FIG. 13B is a cross-sectional view and an electron trajectory diagram of the element 112 in the peripheral portion.
[0156]
Since the central element has a symmetric structure, electrons are emitted in the z direction, and the beam spread is symmetric in the x direction.
[0157]
On the other hand, due to the asymmetry of the peripheral elements, the electron trajectory is bent and the beam spread becomes asymmetric. Further, the direction differs depending on the place where the element is arranged, but all are arranged so that the electron beam is directed toward the center.
[0158]
In this example, when w1 was 1 μm, w3 was 5 μm, and the inter-element spacing was 10 μm, the beam diameter was 190 μm × 190 μm.
[0159]
[Example 4]
FIG. 14 shows a fourth embodiment of the present invention.
[0160]
The present embodiment is a modification in which the same electron-emitting devices as those of the third embodiment are arranged in a circle in one device.
[0161]
In this example, the circularity of the beam was improved as compared with Example 3. On the other hand, since the number of electron-emitting devices is small, the variation rate is slightly increased.
[0162]
[Example 5]
An image forming apparatus was manufactured using the electron-emitting devices of Examples 1 to 4. As an example, a case where the element of Example 1 is used will be described. FIG. 7 is a configuration diagram of an image forming apparatus manufactured using the element of Example 1.
[0163]
The element of Example 1 was arranged in a 100 × 100 MTX shape. The elements were arranged at a pitch of 150 μm in width and 250 μm in length. A phosphor was disposed at a position 2 mm above the element. A voltage of 10 kV was applied to the phosphor. The drive voltage was Vg = 15V. As a result, a high-definition image forming apparatus can be formed.
[0164]
【The invention's effect】
As described above, according to the present invention, it is possible to provide an electron-emitting device that realizes a further reduction in the electron beam diameter, that is easy to manufacture, and that can stably emit electrons at a low voltage with high efficiency. Is possible.
[0165]
In addition, when the electron-emitting device according to the present invention is used, it is possible to realize an electron source and an image forming apparatus with good image quality, high definition, and excellent performance.
[Brief description of the drawings]
FIG. 1 is a plan view showing a configuration of an electron-emitting device according to an embodiment of the present invention.
FIG. 2 is a perspective view showing an electron-emitting device according to an embodiment of the present invention.
FIG. 3 is a diagram showing an electron trajectory of the electron-emitting device according to the embodiment of the present invention.
FIG. 4 is a diagram showing an example of a method for manufacturing an electron-emitting device according to an embodiment of the present invention.
FIG. 5 is a diagram showing an example of an electron source according to an embodiment of the present invention.
FIG. 6 is a schematic configuration diagram showing an electron source having a simple matrix arrangement according to an embodiment of the present invention.
FIG. 7 is a schematic configuration diagram showing an image forming apparatus using an electron source having a simple matrix arrangement according to an embodiment of the present invention.
FIG. 8 is a view showing a fluorescent film in the image forming apparatus according to the embodiment of the present invention.
FIG. 9 is a block diagram illustrating a drive circuit of the image forming apparatus according to the embodiment of the present invention.
FIG. 10 is a diagram showing Example 2 of the present invention.
FIG. 11 is a plan view showing Embodiment 3 of the present invention.
FIG. 12 is a diagram of an element for explaining Example 3 of the invention.
FIG. 13 is a diagram showing an electron trajectory of Example 3 of the present invention.
FIG. 14 is a diagram showing a fourth embodiment of the present invention.
FIG. 15 is a diagram schematically showing a conventional electron-emitting device.
[Explanation of symbols]
1 Substrate
2 Cathode electrode
3 Insulation layer
4a, 4b Gate electrode
5 Electron emission layer
6 Drive power supply
7 Anode electrode
8 High voltage power supply
41 Mask pattern
54, 64, 71 Electron-emitting devices
61, 81 Electron source substrate
62 X-direction wiring
63 Y-direction wiring
85 phosphor
86 Black conductive material
91 Rear plate
92 Support frame
93 Glass substrate
94 Fluorescent membrane
95 metal back
96 face plate
98 Envelope
111 Electron emission part in the center
112 Peripheral electron emission part

Claims (5)

A cathode electrode disposed on the surface of the substrate;
A gate electrode stacked on the cathode electrode through an insulating layer,
A plurality of openings are provided through the insulating layer and the gate electrode to expose a partial region of the cathode electrode, and an electron emission layer electrically connected to the cathode electrode is provided in each opening. In the obtained electron-emitting device,
The shape when the opening is viewed from a direction perpendicular to the surface of the substrate is a ring shape,
The plurality of openings are a plurality of openings arranged in a central portion of the electron-emitting device, and a plurality of openings in a peripheral portion arranged so as to surround the plurality of openings in the central portion. Consists of
The central opening is formed to have side walls of the same height,
The opening in the peripheral part is opposite to the central part rather than the side wall on the central part side in order to deflect the electron beam emitted from the electron emitting layer in the opening in the peripheral part toward the central part. An electric-emitting device, wherein the side wall on the side is formed to be higher.   2. The electron-emitting device according to claim 1, wherein the gate electrode on the side opposite to the central portion is thicker than the gate electrode on the central portion side of the opening in the peripheral portion. The plurality of openings in the central portion are arranged in a matrix,
3. The electron-emitting device according to claim 1, wherein the plurality of openings in the peripheral portion are arranged in a square shape so as to surround four sides of the plurality of openings in the central portion. The plurality of openings in the central portion are arranged in a circle,
3. The electron-emitting device according to claim 1, wherein the plurality of openings in the peripheral portion are concentrically arranged with respect to the plurality of openings in the central portion. An electron-emitting device according to any one of claims 1 to 4, characterized in that the connection portion for connecting the gate electrode of the outside and the gate electrode inside of the ring-shaped opening is provided.

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