JP3624111B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus provided with an inner spacer in order to support atmospheric pressure applied to the outer envelope of the apparatus from the inside of the outer envelope.
[0002]
[Prior art]
Conventionally, two types of electron-emitting devices, a hot cathode device and a cold cathode device, are known. Among these, as the cold cathode device, for example, a surface conduction electron-emitting device, a field emission device (hereinafter referred to as FE type), a metal / insulating layer / metal-type emitting device (hereinafter referred to as MIM type), and the like are known. ing.
[0003]
Examples of surface conduction electron-emitting devices include M.I. I. Elinson, Radio Eng. Electron Phys. , 10, 1290, (1965) and other examples described later.
[0004]
The surface conduction electron-emitting device utilizes a phenomenon in which electron emission occurs when a current flows in parallel to a film surface of a small-area thin film formed on a substrate. As this surface conduction electron-emitting device, Sn by Erinson et al.O ₂ In addition to thin film, Au thin film [G. Dittmer: “Thin SolidFilms”, 9, 317 (1972)],In ₂ O ₃ / SnO ₂ By thin film [M. Hartwell and C.H. G. Fonstad: “IEEE Trans. ED Conf.”, 519 (1975)], carbon thin film [Hisa Araki et al .: Vacuum, Vol. 26, No. 1, 22 (1983)] and the like have been reported.
[0005]
As a typical example of the device configuration of these surface conduction electron-emitting devices, the above-described M.P. FIG. 3 shows a plan view of a device by Hartwell et al. In the figure, reference numeral 3001 denotes a substrate, and 3004 denotes a conductive thin film made of a metal oxide formed by sputtering. The conductive thin film 3004 is formed in an H-shaped planar shape as shown. By applying an energization process called energization forming to be described later to the conductive thin film 3004, an electron emission portion 3005 is formed. The interval L in the drawing is set to 0.5 to 1 [mm], and W is set to 0.1 [mm]. For convenience of illustration, the electron emission portion 3005 is shown as a rectangular shape in the center of the conductive thin film 3004. However, this is a schematic shape and faithfully represents the actual position and shape of the electron emission portion. I don't mean.
[0006]
M.M. In the above-described surface conduction electron-emitting devices such as the device by Hartwell et al., It is common to form the electron-emitting portion 3005 by applying an energization process called energization forming to the conductive thin film 3004 before emitting electrons. Met. That is, the energization forming means that the conductive thin film 3004 is energized by applying a constant DC voltage or a DC voltage boosted at a very slow rate of, for example, about 1 V / min to both ends of the conductive thin film 3004. Is locally destroyed, deformed, or altered to form an electron emitting portion 3005 in an electrically high resistance state. Note that a crack occurs in a part of the conductive thin film 3004 that is locally broken, deformed, or altered. When an appropriate voltage is applied to the conductive thin film 3004 after the energization forming, electrons are emitted in the vicinity of the crack.
[0007]
An example of the FE type is, for example, W.W. P. Dyke & W. W. Dolan, “Field emission”, Advance in ElectroPhysics, 8, 89 (1956), or C.I. A. Spindt, “Physical properties of thin-film field emissions with molecondens cones”, J. Am. Appl. Phys. 47, 5248 (1976).
[0008]
As a typical example of the element configuration of the FE type, the above-described C.I. A. A cross-sectional view of the element according to Spindt et al. Is shown. In this figure, 3010 is a substrate, 3011 is an emitter wiring made of a conductive material, 3012 is an emitter cone, 3013 is an insulating layer, and 3014 is a gate electrode. This element causes field emission from the tip of the emitter cone 3012 by applying an appropriate voltage between the emitter cone 3012 and the gate electrode 3014.
[0009]
As another element configuration of the FE type, there is an example in which an emitter and a gate electrode are arranged on a substrate substantially parallel to the substrate plane, instead of the laminated structure as shown in FIG.
[0010]
Examples of the MIM type include C.I. A. Mead, “Operation of tunnel-emission Devices”, J. Am. Appl. Phys. , 32, 646 (1961) and the like are known. A typical example of the MIM type element configuration is shown in FIG. This figure is a sectional view, in which 3020 is a substrate, 3021 is a lower electrode made of metal, 3022 is a thin insulating layer having a thickness of about 100 angstroms, and 3023 is made of a metal having a thickness of about 80 to 300 angstroms. Electrode.
[0011]
In the MIM type, an appropriate voltage is applied between the upper electrode 3023 and the lower electrode 3021 to cause electron emission from the surface of the upper electrode 3023.
[0012]
Since the above-described cold cathode device can obtain electron emission at a lower temperature than a hot cathode device, a heater for heating is not required. Therefore, the structure is simpler than that of the hot cathode device, and a fine device can be produced. Further, even if a large number of elements are arranged on the substrate at a high density, problems such as thermal melting of the substrate hardly occur. Further, unlike the case where the hot cathode element operates by heating of the heater, the response speed is slow. In the case of the cold cathode element, there is also an advantage that the response speed is fast.
[0013]
For this reason, research for applying cold cathode devices has been actively conducted.
[0014]
For example, a surface conduction electron-emitting device has an advantage that a large number of devices can be formed over a large area because it is particularly simple in structure and easy to manufacture among cold cathode devices. Therefore, for example, as disclosed in Japanese Patent Application Laid-Open No. 64-31332 by the present applicant, a method for arranging and driving a large number of elements has been studied.
[0015]
As for applications of surface conduction electron-emitting devices, for example, image forming apparatuses such as image display apparatuses and image recording apparatuses, charged beam sources, and the like have been studied.
[0016]
In particular, as an application to an image display device, for example, as disclosed in USP 5,066,883, Japanese Patent Application Laid-Open No. 2-257551 and Japanese Patent Application Laid-Open No. 4-28137 by the present applicant, An image display device using a combination of an emission element and a phosphor that emits light when irradiated with an electron beam has been studied. An image display device using a combination of a surface conduction electron-emitting device and a phosphor is expected to have characteristics superior to those of other conventional image display devices. For example, it can be said that it is superior in that it does not require a backlight and has a wide viewing angle as compared with a liquid crystal display device that has been widespread in recent years.
[0017]
A method for driving a plurality of FE types in a row is disclosed, for example, in USP 4,904,895 by the present applicant. As an example of applying the FE type to an image display device, for example, R.I. A flat panel display device reported by Meyer et al. Is known. [R. Meyer: “Recent Development on Microtips Display at LETI”, Tech. Digest of 4th Int. Vacuum Microele-tronics Conf. , Nagahama, pp. 6-9 (1991)]
An example in which a large number of MIM types are arranged and applied to an image display device is disclosed in, for example, Japanese Patent Application Laid-Open No. 3-55738 by the present applicant.
[0018]
Among the image forming apparatuses using the electron-emitting devices as described above, a flat-type display device with a small depth is attracting attention as a replacement for a CRT type display device because it is space-saving and lightweight.
[0019]
FIG. 23 is a perspective view showing an example of a display panel portion constituting a flat type image display device, and a part of the panel is cut away to show the internal structure.
[0020]
In the figure, 3115 is a rear plate, 3116 is a side wall, and 3117 is a face plate. The rear plate 3115, the side wall 3116 and the face plate 3117 provide an envelope (airtight container) for maintaining the inside of the display panel in a vacuum. Forming.
[0021]
A substrate 3111 is fixed to the rear plate 3115, and n × m cold cathode elements 3112 are formed on the substrate 3111. (N and m are positive integers of 2 or more and are appropriately set according to the target number of display pixels.) Further, the n × m cold cathode elements 3112 include m as shown in FIG. Wiring is performed by one row direction wiring 3113 and n number of column direction wirings 3114. A portion constituted by the substrate 3111, the cold cathode element 3112, the row direction wiring 3113, and the column direction wiring 3114 is referred to as a multi-electron beam source. In addition, an insulating layer (not shown) is formed between both the wirings in the row direction wiring 3113 and the column direction wiring 3114 so that electrical insulation is maintained.
[0022]
A phosphor film 3118 made of phosphor is formed on the lower surface of the face plate 3117, and phosphors (not shown) of three primary colors of red (R), green (G), and blue (B) are separately applied. Yes. Further, a black body (not shown) is provided between the color phosphors forming the fluorescent film 3118, and a metal back 3119 made of Al or the like is formed on the surface of the fluorescent film 3118 on the rear plate 3115 side. ing.
[0023]
Dx1 to Dxm and Dy1 to Dyn and Hv are electrical connection terminals having an airtight structure provided to electrically connect the display panel and an electric circuit (not shown). Dx1 to Dxm are electrically connected to the row direction wiring 3113 of the multi electron beam source, Dy1 to Dyn are electrically connected to the column direction wiring 3114 of the multi electron beam source, and Hv is electrically connected to the metal back 3119.
[0024]
Further, the inside of the hermetic container is maintained at a vacuum of about 10 to the sixth power of Torr, and as the display area of the image display device increases, the rear plate 3115 and the face plate due to a difference in atmospheric pressure between the inside and outside of the hermetic container. A means for preventing the deformation or destruction of 3117 is required. The method of increasing the thickness of the rear plate 3115 and the face plate 3116 not only increases the weight of the image display device, but also causes image distortion and parallax when viewed from an oblique direction. On the other hand, in FIG. 24, a structural support (called a spacer or a rib) 3120 made of a relatively thin glass plate and supporting atmospheric pressure is provided. In this way, the space between the substrate 3111 on which the multi-beam electron source is formed and the face plate 3116 on which the fluorescent film 3118 is formed is normally maintained at a submillimeter to several millimeters, and the inside of the hermetic container is maintained at a high vacuum as described above. ing.
[0025]
In the image display device using the display panel described above, when a voltage is applied to each cold cathode element 3112 through the external terminals Dx1 to Dxm and Dy1 to Dyn, electrons are emitted from each cold cathode element 3112. At the same time, a high voltage of several hundred [V] to several [kV] is applied to the metal back 3119 through the container outer terminal Hv to accelerate the emitted electrons and collide with the inner surface of the face plate 3117. As a result, the phosphors of the respective colors forming the fluorescent film 3118 are excited to emit light, and an image is displayed.
[0026]
The electron beam apparatus of the image forming apparatus described above has an envelope, an electron source, and an electron irradiation member for maintaining a vacuum atmosphere in the apparatus, and further, an atmospheric pressure applied to the envelope is supplied from the inside of the envelope. A spacer for supporting is arranged in the envelope.
[0027]
In particular, in the image forming apparatus such as the display apparatus described above, in order to realize a large area of the image display apparatus and a thinning of the apparatus, it is indispensable to arrange a spacer inside the envelope.
[0028]
[Problems to be solved by the invention]
However, when the spacer is arranged in the image forming apparatus, there is a problem that the irradiation position of the electron beam on the electron irradiation surface is deviated from the design position. In this case, for example, it means a deviation from the design value of the irradiation position of the electron beam or the light emission shape on the phosphor surface. In particular, when an image forming member provided with RGB phosphors for color images is used sometimes, a decrease in luminance or color shift may be observed along with the irradiation position of the electron beam. This phenomenon occurs particularly in the vicinity of the electron source, the image forming member, and spacers arranged in the vicinity thereof.
[0029]
The cause of this phenomenon is as follows.
[0030]
When electrons emitted from the electron source are irradiated on the irradiation member, a phenomenon occurs in which a part of the electrons is reflected by the irradiation member and ions are emitted from the irradiation member by the electron irradiation. The emitted electrons and ions cause charging of the insulating member when an insulating member is present in the vicinity. There are adhesion of radiated electrons and ions to an insulator, and charging due to generation of secondary electrons by rushing of the radiated electrons into the insulator.
[0031]
As the charging of the insulator proceeds, the surrounding electric field changes, and is then emitted from the electron source to cause a shift in the electron trajectory. As a result, there are problems such that electrons are not incident on the phosphor to emit light and other phosphors emit light.
[0032]
Not only the insulator disposed in the image display area, but also the insulator portion in the vicinity of the image display area is charged, causing a shift of the electron trajectory.
[0033]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to prevent a positional deviation of an electron beam that occurs in an irradiation member of an electron source in the entire area and prevent a decrease in luminance and a color deviation in an image forming apparatus.
[0034]
[Means for Solving the Problems]
Electron emitterHaveElectron sourceWas placedElectron source areaRear plate withAnd to irradiate the electrons emitted from the electron source,Accelerating voltage for accelerating electrons emitted from the electron-emitting device, which are arranged opposite to the electron source in a vacuum atmosphere.Irradiation member region where electron irradiation member to which is applied is arrangedHaveFace plateAnd saidRear plateAnd saidFace platePlaced betweenAn envelope including a support frame, and a plurality of the envelopes disposed inside the envelopeIn an image forming apparatus having a spacer,Of the plurality of spacers, if the distance between the rear plate and the face plate is d, the electron source region and the adjacent region in the range of 2d from the outer periphery of the electron source region, or the irradiation member region and the The spacers disposed in the adjacent region within the range of 2d from the outer periphery of the irradiation member region are conductive, and the spacers disposed in the region other than the region are insulative.
[0035]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0036]
FIG. 1 is a perspective view of a display panel provided in the image forming apparatus of the present invention, and a part of the panel is cut away to show the internal structure.
[0037]
In the figure, 1015 is a rear plate, 1016 is a side wall, 1017 is a face plate, and 1015 to 1017 form an airtight container for maintaining the inside of the display panel in a vacuum. When assembling an airtight container, it is necessary to seal the joints of each member in order to maintain sufficient strength and airtightness. For example, frit glass is applied to the joints, and in the air or in a nitrogen atmosphere, Celsius. Sealing was achieved by baking at 400 to 500 degrees for 10 minutes or more. A method for evacuating the inside of the hermetic container will be described later. In addition, since the inside of the airtight container is maintained in a vacuum of about 10 to the sixth power [Torr], for the purpose of preventing destruction of the airtight container due to atmospheric pressure or unexpected impact, as an atmospheric pressure resistant structure, A spacer 1020 is provided.
[0038]
Next, an electron-emitting device substrate that can be used in the image forming apparatus of the present invention will be described. The electron source substrate used in the image forming apparatus of the present invention is formed by arranging a plurality of cold cathode elements on the substrate.
[0039]
The cold cathode element arrangement method includes a ladder arrangement in which cold cathode elements are arranged in parallel and both ends of each element are connected by wiring (hereinafter referred to as a ladder arrangement electron source substrate), A simple matrix arrangement (hereinafter referred to as a matrix-type arrangement electron source substrate) in which a pair of element electrodes are connected to each other in the X-direction wiring and the Y-direction wiring is exemplified. An image forming apparatus having a ladder-type arrangement electron source substrate requires a control electrode (grid electrode) that is an electrode for controlling the flight of electrons from the electron-emitting device.
[0040]
A substrate 1011 is fixed to the rear plate 1015, and n × m cold cathode elements 1012 are formed on the substrate. (N and m are positive integers of 2 or more, and are appropriately set according to the target number of display pixels. For example, in a display device for display of high-definition television, n = 3000, m. It is desirable to set a number equal to or greater than 1000.) The n × m cold cathode elements are simply matrix-wired by m row-direction wirings 1013 and n column-direction wirings 1014. The part constituted by 1011 to 1014 is called a multi-electron beam source.
[0041]
The multi-electron beam source used in the image display apparatus of the present invention is not limited in the material, shape, or manufacturing method of the cold cathode element as long as the cold cathode element is an electron source having a simple matrix wiring or ladder arrangement.
[0042]
Therefore, for example, a cold cathode device such as a surface conduction electron-emitting device, FE type, or MIM type can be used.
[0043]
Next, the structure of a multi-electron beam source in which surface conduction electron-emitting devices as cold cathode devices are arranged on a substrate and wired in a simple matrix will be described.
[0044]
FIG. 2 is a plan view of the multi-electron beam source used in the display panel of FIG. On the substrate 1011, surface conduction electron-emitting devices are arranged, and these devices are wired in a simple matrix by row direction wirings 1013 and column direction wirings 1014. An insulating layer (not shown) is formed between the electrodes at a portion where the row direction wiring 1013 and the column direction wiring 1014 intersect, and electrical insulation is maintained.
[0045]
A cross section taken along the line BB 'of FIG. 2 is shown in FIG.
[0046]
The multi-electron source having such a structure has a row-direction wiring 1013, a column-direction wiring 1014, an interelectrode insulating layer (not shown), an element electrode of a surface conduction electron-emitting device, and a conductive thin film in advance on a substrate. After the formation, it was manufactured by supplying power to each element via the row direction wiring 1013 and the column direction wiring 1014 and performing energization forming processing (described later) and energization activation processing (described later).
[0047]
In the present embodiment, the multi-electron beam source substrate 1011 is fixed to the rear plate 1015 of the hermetic container. However, if the multi-electron beam source substrate 1011 has sufficient strength, the hermetic container The multi-electron beam source substrate 1011 itself may be used as the rear plate.
[0048]
A fluorescent film 1018 is formed on the lower surface of the face plate 1017. Since this embodiment is a color display device, the phosphor film 1018 is coated with phosphors of three primary colors red, green and blue used in the field of CRT. For example, as shown in FIG. 4A, the phosphors of the respective colors are separately applied in stripes, and a black conductor 1010 is provided between the stripes of the phosphors. The purpose of providing the black conductor 1010 is to prevent the display color from being shifted even if there is a slight shift in the irradiation position of the electron beam, or to prevent the reflection of external light and lower the display cost last. For example, preventing the phosphor film from being charged up by an electron beam. For the black conductor 1010, graphite is used as a main component, but other materials may be used as long as they are suitable for the above purpose.
[0049]
In addition, the method of separately applying the phosphors of the three primary colors is not limited to the stripe arrangement shown in FIG. 4A. For example, the delta arrangement shown in FIG. It may be an array.
[0050]
Note that when a monochrome display panel is formed, a monochromatic phosphor material may be used for the phosphor film 1018, and a black conductive material is not necessarily used.
[0051]
Further, a metal back 1019 known in the field of CRT is provided on the surface of the fluorescent film 1018 on the rear plate side. The purpose of providing the metal back 1019 is to improve the light utilization rate by specularly reflecting a part of the light emitted from the fluorescent film 1018, to protect the fluorescent film 1018 from the collision of negative ions, and the electron beam acceleration voltage. For example, to act as an electrode for applying a voltage, or to act as a conductive path for excited electrons in the fluorescent film 1018. The metal back 1019 was formed by forming a fluorescent film 1018 on the face plate substrate 1017, smoothing the surface of the fluorescent film, and then vacuum-depositing Al thereon. Note that when a low-voltage phosphor material is used for the fluorescent film 1018, the metal back 1019 is not used.
[0052]
Further, for the purpose of applying an acceleration voltage or improving the conductivity of the fluorescent film, a transparent electrode made of, for example, ITO may be provided between the face plate substrate 1017 and the fluorescent film 1018.
[0053]
The spacer disposed in the image display area will be described. FIG. 5 is a schematic cross-sectional view of an enlarged portion of the AA ′ spacer 1020 in FIG. 1, and the numbers of the respective parts correspond to those in FIG. The spacer 1020A forms a high-resistance film 11 for preventing charging on the surface of the insulating member 1, and the inside of the face plate 1017 (metal back 1019 and the like) and the surface of the substrate 1011 (row-direction wiring 1013 or column direction). It consists of a member having a low resistance film 21 formed on the contact surface 3 of the spacer facing the wiring 1014) and the side surface portion 5 in contact with the spacer, and has a necessary number of intervals to achieve the above object. And is fixed to the inside of the face plate and the surface of the substrate 1011 with a bonding material 1041. The high resistance film is formed on at least the surface of the insulating member 1 exposed in the vacuum in the hermetic container, and the low resistance film 21 on the spacer 1020A and the bonding material 1041 are interposed therebetween. Then, they are electrically connected to the inside of the face plate 1017 (metal back 1019 and the like) and the surface of the substrate 1011 (row direction wiring 1013 or column direction wiring 1014). In the embodiment described here, the spacer 1020 has a thin plate shape, is arranged in parallel to the row direction wiring 1013, and is electrically connected to the row direction wiring 1013.
[0054]
The spacer 1020 has an insulating property to withstand a high voltage applied between the row direction wiring 1013 and the column direction wiring 1014 on the substrate 1011 and the metal back 1019 on the inner surface of the face plate 1017, and the spacer 1020 It is necessary to have conductivity sufficient to prevent the surface from being charged.
[0055]
Examples of the insulating member 1 of the spacer 1020 include quartz glass, glass with a reduced impurity content such as Na, ceramic member such as soda lime glass, and alumina. The insulating member 1 preferably has a thermal expansion coefficient close to that of the member forming the hermetic container and the substrate 1011.
[0056]
The high resistance film 11 constituting the spacer 1020 has a current obtained by dividing the acceleration voltage Va applied to the high potential side face plate 1017 (metal back 1019 or the like) by the resistance value Rs of the high resistance film 21 as an antistatic film. Will be washed away. Therefore, the resistance value Rs of the spacer is set in a desirable range from antistatic and power consumption. From the viewpoint of preventing charging, the surface resistance R / □ is preferably 10 12 Ω or less. In order to obtain a sufficient antistatic effect, 10 11 Ω or less is more preferable. The lower limit of the surface resistance depends on the spacer shape and the voltage applied between the spacers, but is preferably 10 5 Ω or more.
[0057]
The thickness t of the antistatic film formed on the insulating material is preferably in the range of 10 nm to 1 μm. Although it varies depending on the surface energy of the material, adhesion to the substrate, and substrate temperature, a thin film of 10 nm or less is generally formed in an island shape, and its resistance is unstable and reproducibility is poor. On the other hand, when the film thickness t is 1 μm or more, the film stress increases, the risk of film peeling increases, and the film formation time increases, resulting in poor productivity. Therefore, the film thickness is desirably 50 to 500 nm. The surface resistance R / □ is ρ / t, and the specific resistance ρ of the antistatic film is preferably 0.1 [Ωcm] to 10 8 [Ωcm] from the preferable range of R □ and t described above. . Furthermore, in order to realize a more preferable range of surface resistance and film thickness, ρ is preferably set to 10 2 to 10 6 Ωcm.
[0058]
As described above, the temperature of the spacer rises when a current flows through the antistatic film formed thereon or when the entire display generates heat during operation. When the resistance temperature coefficient of the antistatic film is a large negative value, the resistance value decreases when the temperature rises, the current flowing through the spacer increases, and the temperature rises further. The current continues to increase until it exceeds the power supply limit. The value of the resistance temperature coefficient at which such a current runaway occurs is empirically a negative value and the absolute value is 1% or more. That is, the resistance temperature coefficient of the antistatic film is desirably less than −1%.
[0059]
As a material of the high resistance film 11 having antistatic properties, for example, a metal oxide can be used. Among metal oxides, chromium, nickel, and copper oxides are preferable materials. The reason for this is considered that these oxides have a relatively low secondary electron emission efficiency and are difficult to be charged even when electrons emitted from the cold cathode element 1012 hit the spacer 1020. Besides metal oxides, carbon is a preferable material because it has a low secondary electron emission efficiency. In particular, since amorphous carbon has high resistance, it is easy to control the spacer resistance to a desired value.
[0060]
As another material of the high resistance film 11 having antistatic properties, the nitride of aluminum and transition metal alloy can control the resistance value in a wide range from a good conductor to an insulator by adjusting the composition of the transition metal. It is a suitable material. Furthermore, it is a stable material with little change in resistance value in the manufacturing process of the display device described later. In addition, the temperature coefficient of resistance is less than -1%, and it is a material that is practically easy to use. Examples of the transition metal element include Ti, Cr, Ta and the like.
[0061]
The alloy nitride film is formed on the insulating member by thin film forming means such as sputtering, reactive sputtering in a nitrogen gas atmosphere, electron beam vapor deposition, ion plating, or ion assist vapor deposition. The metal oxide film can also be produced by a similar thin film formation method, but in this case, oxygen gas is used instead of nitrogen gas. In addition, a metal oxide film can be formed by a CVD method or an alkoxide coating method. The carbon film is produced by vapor deposition, sputtering, CVD, or plasma CVD. In particular, when producing amorphous carbon, the atmosphere during film formation should contain hydrogen or be used as a film formation gas. Use hydrocarbon gas.
[0062]
The low resistance film 21 constituting the spacer 1020A is for electrically connecting the high resistance film 11 to the face plate 1017 (metal back 1019 and the like) on the high potential side and the substrate 1011 (wirings 1013 and 1014 and the like) on the low potential side. In the following, the name of an intermediate electrode layer (intermediate layer) is also used. The intermediate electrode layer (intermediate layer) can have a plurality of functions listed below.
[0063]
The high resistance film 11 is electrically connected to the face plate 1017 and the substrate 1011.
[0064]
As already described, the high resistance film 11 is provided for the purpose of preventing charging on the surface of the spacer 1020. However, the high resistance film 11 is formed by using the face plate 1017 (metal back 1019 or the like) and the substrate 1011 (wiring 1013). 1014) directly or via the contact member 1041, a large contact resistance is generated at the interface of the connection portion, and there is a possibility that the charge generated on the spacer surface cannot be quickly removed. In order to avoid this, a low-resistance intermediate layer is provided on the contact surface 3 or the side surface portion 5 of the spacer 1020 that contacts the face plate 1017, the substrate 1011, and the contact material 1041.
[0065]
Electrons emitted from the cold cathode element 1012 form an electron trajectory according to a potential distribution formed between the face plate 1017 and the substrate 1011. In order to prevent disturbance of the electron trajectory in the vicinity of the spacer 1020, it is necessary to control the potential distribution of the high resistance film 11 over the entire region. When the high resistance film 11 is connected to the face plate 1017 (metal back 1019, etc.) and the substrate 1011 (wirings 1013, 1014, etc.) directly or via the contact material 1041, the connection state is caused due to the contact resistance at the interface of the connection portion. May occur, and the potential distribution of the high resistance film 11 may deviate from a desired value. In order to avoid this, a low resistance intermediate layer is provided in the entire length region of the spacer end portion (contact surface 3 or side surface portion 5) where the spacer 1020 contacts the face plate 1017 and the substrate 1011. By applying a potential, the potential of the entire high resistance film 11 can be controlled.
[0066]
Electrons emitted from the cold cathode element 1012 form an electron trajectory according to a potential distribution formed between the face plate 1017 and the substrate 1011. With respect to electrons emitted from the cold cathode device in the vicinity of the spacer, restrictions (wiring, change of device position, etc.) associated with the installation of the spacer may occur. In such a case, in order to form an image without distortion or unevenness, it is necessary to control the trajectory of the emitted electrons to irradiate the desired position on the face plate 1017 with electrons. By providing a low resistance intermediate layer on the side surface portion 5 of the face plate 1017 and the substrate 1011 in contact with the surface plate 1017, the potential distribution in the vicinity of the spacer 1020 can have desired characteristics and the trajectory of emitted electrons can be controlled. I can do it.
[0067]
The low resistance film 21 may be selected from a material having a sufficiently low resistance value as compared with the high resistance film 11, and may be a metal such as Ni, Cr, Au, Mo, W, Pt, Ti, Al, Cu, Pd, or the like. Alloys and Pd, Ag, Au, RuO ₂, Printed conductors composed of metals such as Pd-Ag and metal oxides and glass, orIn ₂ O ₃-SnO ₂The material is appropriately selected from a transparent conductor such as polysilicon and a semiconductor material such as polysilicon.
[0068]
The bonding material 1041 needs to have conductivity so that the spacer 1020 is electrically connected to the row direction wiring 1013 and the metal back 1019. That is, a frit glass to which a conductive adhesive, metal particles, or a conductive filler is added is suitable.
[0069]
Dx1 to Dxm and Dy1 to Dyn and Hv are electrical connection terminals having an airtight structure provided for electrically connecting the display panel and an electric circuit (not shown). Dx1 to Dxm are electrically connected to the row-direction wiring 1013 of the multi-electron beam source, Dy1 to Dyn are electrically connected to the column-direction wiring 1014 of the multi-electron beam source, and Hv is electrically connected to the metal back 1019 of the face plate.
[0070]
Further, in order to evacuate the inside of the hermetic container to a vacuum, after assembling the hermetic container, an unillustrated exhaust pipe and a vacuum pump are connected, and the inside of the hermetic container has a degree of vacuum of about 10 to the seventh power [Torr]. Exhaust. Thereafter, the exhaust pipe is sealed. In order to maintain the degree of vacuum in the hermetic container, a getter film (not shown) is formed at a predetermined position in the hermetic container immediately before or after sealing. The getter film is, for example, a film formed by heating and vapor-depositing a getter material mainly composed of Ba by a heater or high-frequency heating, and the inside of the hermetic container is 1 × 10 minus 5 to 1 or 1 by the adsorption action of the getter film. The degree of vacuum is maintained at x10 minus 7 [Torr].
[0071]
In the image display device using the display panel described above, electrons are emitted from each cold cathode element 1012 when a voltage is applied to each cold cathode element 1012 through the external terminals Dx1 to Dxm and Dy1 to Dyn. At the same time, a high voltage of several hundred [V] to several [kV] is applied to the metal back 1019 through the container outer terminal Hv to accelerate the emitted electrons and collide with the inner surface of the face plate 1017. Thereby, the phosphors of the respective colors forming the fluorescent film 1018 are excited to emit light, and an image is displayed.
[0072]
Usually, the voltage applied to 1012 to the surface conduction electron-emitting device of the present invention, which is a cold cathode device, is about 12 to 16 [V], and the distance d between the metal back 1019 and the cold cathode device 1012 is 0.1 [mm]. ] To about 8 [mm], and the voltage between the metal back 1019 and the cold cathode element 1012 is about 0.1 [kV] to about 10 [kV].
[0073]
The basic configuration and manufacturing method of the display panel of the present invention and the outline of the image display device have been described above.
[0074]
Next, the manufacturing method of the multi electron beam source used for the display panel will be described. The multi-electron beam source used in the image display apparatus of the present invention is not limited in the material, shape or manufacturing method of the cold cathode element as long as it is an electron source in which cold cathode elements are wired in a simple matrix. Therefore, for example, a cold cathode device such as a surface conduction electron-emitting device, FE type, or MIM type can be used.
[0075]
However, a surface conduction electron-emitting device is particularly preferable among these cold cathode devices under a situation where a display device having a large display screen and a low price is required. That is, in the FE type, the relative position and shape of the emitter cone and the gate electrode greatly affect the electron emission characteristics, and thus an extremely accurate manufacturing technique is required. This achieves a large area and a reduction in manufacturing cost. This is a disadvantageous factor. Further, in the MIM type, it is necessary to make the insulating layer and the upper electrode thin and uniform, but this is also a disadvantageous factor in achieving a large area and a reduction in manufacturing cost. In that respect, since the surface conduction electron-emitting device is relatively simple to manufacture, it is easy to increase the area and reduce the manufacturing cost. The inventors have also found that among surface conduction electron-emitting devices, those in which the electron-emitting portion or its peripheral portion is formed of a fine particle film are particularly excellent in electron-emitting characteristics and can be easily manufactured. Therefore, it can be said that it is most suitable for use in a multi-electron beam source of a high-luminance and large-screen image display device. Therefore, in the display panel of the above embodiment, a surface conduction electron-emitting device in which the electron emitting portion or its peripheral portion is formed of a fine particle film is used. First, the basic configuration, manufacturing method, and characteristics of a suitable surface conduction electron-emitting device will be described, and then the structure of a multi-electron beam source in which a number of devices are simply matrix-wired will be described.
[0076]
(Suitable device structure and manufacturing method of surface conduction electron-emitting device)
There are two types of typical structures of the surface conduction electron-emitting device in which the electron-emitting portion or its peripheral portion is formed of a fine particle film, a planar type and a vertical type.
[0077]
(Plane type surface conduction electron-emitting device)
First, the device configuration and manufacturing method of a planar surface conduction electron-emitting device will be described.
[0078]
FIG. 6 shows a plan view (a) and a cross-sectional view (b) for explaining the configuration of a planar surface conduction electron-emitting device. In the figure, 1101 is a substrate, 1102 and 1103 are element electrodes, 1104 is a conductive thin film, 1105 is an electron emission portion formed by energization forming treatment, and 1113 is a thin film formed by energization activation treatment.
[0079]
As the substrate 1101, for example, various glass substrates including quartz glass and blue plate glass, various ceramic substrates including alumina, or the above-described various substrates such as SiO ₂ A substrate on which an insulating layer made of a material is stacked can be used.
[0080]
In addition, element electrodes 1102 and 1103 provided on the substrate 1101 so as to face the substrate surface in parallel are formed of a conductive material. For example, metals such as Ni, Cr, Au, Mo, W, Pt, Ti, Cu, Pd, Ag, etc., or alloys of these metals, orIn ₂ O ₃ -SnO ₂ A material may be appropriately selected from metal oxides such as silicon, semiconductors such as polysilicon, and the like. In order to form the electrode, it can be easily formed by using a combination of a film forming technique such as vacuum deposition and a patterning technique such as photolithography and etching, but it can be formed by using other methods (for example, a printing technique). No problem.
[0081]
The shapes of the device electrodes 1102 and 1103 are appropriately designed according to the application purpose of the electron-emitting device. In general, the electrode interval L is usually designed by selecting an appropriate value from the range of several hundreds of angstroms to several hundreds of micrometers, but among them, a number more preferable than several micrometers is preferred for application to a display device. It is in the range of ten micrometers. As for the thickness d of the device electrode, an appropriate value is usually selected from the range of several hundred angstroms to several micrometers.
[0082]
A fine particle film is used for the conductive thin film 1104. The fine particle film described here refers to a film (including an island-like aggregate) containing a large number of fine particles as a constituent element. If the fine particle film is examined microscopically, usually, a structure in which individual fine particles are arranged apart from each other, a structure in which the fine particles are adjacent to each other, or a structure in which the fine particles overlap each other is observed.
[0083]
The particle diameter of the fine particles used for the fine particle film is in the range of several angstroms to several thousand angstroms, and the preferred one is in the range of 10 angstroms to 200 angstroms. The film thickness of the fine particle film is appropriately set in consideration of various conditions as described below. That is, the condition necessary for electrically connecting to the element electrode 1102 or 1103, the condition necessary for satisfactorily performing energization forming described later, and the electric resistance of the particulate film itself to an appropriate value described later. The conditions necessary for Specifically, it is set within the range of several angstroms to several thousand angstroms, and is preferably between 10 angstroms and 500 angstroms.
[0084]
Examples of materials that can be used to form the fine particle film include Pd, Pt, Ru, Ag, Au, Ti, In, Cu, Cr, Fe, Zn, Sn, Ta, W, and Pb. Starting metals, PdO, SnO ₂ ,In ₂ O ₃, PbO,Sb ₂ O ₃ , And other oxides, and HfB ₂, ZrB ₂ , LaB ₆ , CeB ₆ , YB ₄ , GdB ₄ , Borides such as TiC, ZrC, HfC, TaC, SiC, WC, etc., nitrides such as TiN, ZrN, HfN, etc., Si, Ge, etc. And the like, carbon, and the like, which are appropriately selected from these.
[0085]
As described above, the conductive thin film 1104 is formed of a fine particle film, and the sheet resistance value is set to fall within the range of 10 3 to 10 7 [Ohm / sq].
[0086]
Note that it is desirable that the conductive thin film 1104 and the element electrodes 1102 and 1103 be electrically connected to each other, and thus a structure in which a part of the conductive thin film 1104 and the element electrodes 1102 and 1103 overlap each other is employed. In the example of FIG. 6, the layers are stacked from the bottom in the order of the substrate, the device electrode, and the conductive thin film. However, in some cases, the substrate, the conductive thin film, and the device electrode are stacked in this order. No problem.
[0087]
In addition, the electron emission portion 1105 is a crack-like portion formed in a part of the conductive thin film 1104, and has an electrical property higher than that of the surrounding conductive thin film. The crack is formed by performing an energization forming process to be described later on the conductive thin film 1104. There are cases where fine particles having a particle diameter of several angstroms to several hundred angstroms are arranged in the crack. In addition, since it is difficult to accurately and accurately illustrate the actual position and shape of the electron-emitting portion, it is schematically shown in FIG.
[0088]
The thin film 1113 is a thin film made of carbon or a carbon compound, and covers the electron emission portion 1105 and the vicinity thereof. The thin film 1113 is formed by performing an energization activation process described later after the energization forming process.
[0089]
The thin film 1113 is one of single crystal graphite, polycrystalline graphite, and amorphous carbon, or a mixture thereof. The film thickness is 500 [angstroms] or less, but is preferably 300 [angstroms] or less. preferable. In addition, since it is difficult to accurately illustrate the position and shape of the actual thin film 1113, it is schematically shown in FIG. In addition, in the plan view (a), an element from which a part of the thin film 1113 is removed is shown.
[0090]
The basic configuration of the preferred element has been described above. In the examples, the following elements were used.
[0091]
That is, blue plate glass was used for the substrate 1101, and Ni thin films were used for the device electrodes 1102 and 1103. The thickness d of the device electrode was 1000 [angstrom], and the electrode interval L was 2 [micrometer].
[0092]
Pd or PdO was used as a main material of the fine particle film, the thickness of the fine particle film was about 100 [angstrom], and the width W was 100 [micrometer].
[0093]
Next, a preferred method for manufacturing a planar surface conduction electron-emitting device will be described.
[0094]
7A to 7D are cross-sectional views for explaining the manufacturing process of the surface conduction electron-emitting device, and the notations of the respective members are the same as those in FIG.
[0095]
1) First, as shown in FIG. 7A, device electrodes 1102 and 1103 are formed on a substrate 1101.
[0096]
In the formation, the substrate 1101 is sufficiently cleaned in advance using a detergent, pure water, and an organic solvent, and then the element electrode material is deposited. (For example, a vacuum film forming technique such as a vapor deposition method or a sputtering method may be used as a deposition method.) Thereafter, the deposited electrode material is patterned using a photolithography / etching technique, and (a) is formed. The pair of element electrodes (1102 and 1103) shown are formed.
[0097]
2) Next, a conductive thin film 1104 is formed as shown in FIG.
[0098]
In forming the film, first, an organic metal solution is applied to the substrate (a), dried, heated and fired to form a fine particle film, and then patterned into a predetermined shape by photolithography and etching. Here, the organometallic solution is a solution of an organometallic compound whose main element is a fine particle material used for the conductive thin film. (Specifically, Pd was used as the main element in this example. Also, in this example, the dipping method was used as the coating method, but other methods such as spinner method and spray method may be used.)
In addition, as a method for forming a conductive thin film made of a fine particle film, for example, a vacuum evaporation method, a sputtering method, a chemical vapor deposition method, or the like other than the method by application of an organometallic solution used in this embodiment is used. Sometimes used.
[0099]
3) Next, as shown in FIG. 5C, an appropriate voltage is applied between the forming power supply 1110 between the device electrodes 1102 and 1103, and energization forming processing is performed to form the electron emission portion 1105.
[0100]
The energization forming process is a process in which a conductive thin film 1104 made of a fine particle film is energized, and a part thereof is appropriately destroyed, deformed, or altered, and changed into a structure suitable for electron emission. That is. In a portion of the conductive thin film made of the fine particle film that has been changed to a structure suitable for electron emission (that is, the electron emission portion 1105), an appropriate crack is formed in the thin film. Note that the electrical resistance measured between the device electrodes 1102 and 1103 significantly increases after the formation, compared to before the electron emission portion 1105 is formed.
[0101]
In order to describe the energization method in more detail, FIG. 8 shows an example of an appropriate voltage waveform applied from the forming power supply 1110. When forming a conductive thin film made of a fine particle film, a pulsed voltage is preferable. In this embodiment, a triangular wave pulse having a pulse width T1 is continuously applied at a pulse interval T2 as shown in FIG. Applied. At that time, the peak value Vpf of the triangular wave pulse was boosted sequentially. Further, a monitor pulse Pm for monitoring the formation state of the electron emission portion 1105 was inserted between the triangular wave pulses at an appropriate interval, and the current flowing at that time was measured by an ammeter 1111.
[0102]
In the embodiment, for example, in a vacuum atmosphere of about 10 to the fifth power [torr], for example, the pulse width T1 is set to 1 [millisecond], the pulse interval T2 is set to 10 [milliseconds], and the peak value Vpf is set for each pulse. The voltage was increased by 0.1 [V]. The monitor pulse Pm was inserted at a rate of once every time 5 pulses of the triangular wave were applied. The monitor pulse voltage Vpm was set to 0.1 [V] so as not to adversely affect the forming process. Then, when the electrical resistance between the element electrodes 1102 and 1103 becomes 1 × 10 6 [Ohm], that is, when the monitor pulse is applied, the current measured by the ammeter 1111 is 1 × 10 minus 7 [A At the following stage, the energization related to the forming process was terminated.
[0103]
The above method is a preferred method for the surface conduction electron-emitting device of the present embodiment. For example, when the design of the surface conduction electron-emitting device such as the material and film thickness of the fine particle film or the device electrode interval L is changed. Therefore, it is desirable to change the energization conditions accordingly.
[0104]
4) Next, as shown in FIG. 7D, an appropriate voltage is applied between the activation power supply 1112 between the device electrodes 1102 and 1103, and the energization activation process is performed to improve the electron emission characteristics. Do.
[0105]
The energization activation process is a process of energizing the electron emission portion 1105 formed by the energization forming process under appropriate conditions and depositing carbon or a carbon compound in the vicinity thereof. (In the figure, a deposit made of carbon or a carbon compound is schematically shown as the member 1113.) Note that, by conducting the energization activation process, the emission current at the same applied voltage is typically compared to before the conducting. Specifically, it can be increased 100 times or more.
[0106]
Specifically, by applying a voltage pulse periodically in a vacuum atmosphere within a range of 10 minus 4 to 10 minus 5 [torr], an organic compound existing in the vacuum atmosphere originates. Deposit carbon or carbon compounds. The deposit 1113 is one of single crystal graphite, polycrystalline graphite, and amorphous carbon, or a mixture thereof, and has a film thickness of 500 [angstrom] or less, more preferably 300 [angstrom] or less.
[0107]
In order to describe the energization method in more detail, FIG. 9A shows an example of an appropriate voltage waveform applied from the activation power supply 1112. In this embodiment, the energization activation process is performed by periodically applying a rectangular wave having a constant voltage. Specifically, the rectangular wave voltage Vac is 14 [V] and the pulse width T3 is 1 [mm]. Second] and the pulse interval T4 was 10 [milliseconds]. The energization conditions described above are preferable conditions for the surface conduction electron-emitting device of this example. When the design of the surface conduction electron-emitting device is changed, it is desirable to change the conditions accordingly. .
[0108]
Reference numeral 1114 shown in FIG. 7D denotes an anode electrode for capturing the emission current Ie emitted from the surface conduction electron-emitting device, to which a DC high voltage power source 1115 and an ammeter 1116 are connected. (When the activation process is performed after the substrate 1101 is incorporated in the display panel, the phosphor screen of the display panel is used as the anode electrode 1114.) While the voltage is applied from the activation power supply 1112, the current is applied. The emission current Ie is measured by the total 1116 to monitor the progress of the energization activation process, and the operation of the activation power supply 1112 is controlled.
[0109]
FIG. 9B shows an example of the emission current Ie measured by the ammeter 1116. When a pulse voltage starts to be applied from the activation power supply 1112, the emission current Ie increases with time, but eventually saturates and hardly increases. As described above, when the emission current Ie is almost saturated, the voltage application from the activation power supply 1112 is stopped, and the energization activation process is ended.
[0110]
The energization conditions described above are preferable conditions for the surface conduction electron-emitting device of this example. When the design of the surface conduction electron-emitting device is changed, it is desirable to change the conditions accordingly. .
[0111]
As described above, the planar surface conduction electron-emitting device shown in FIG.
[0112]
(Vertical surface conduction electron-emitting devices)
Next, another typical configuration of the surface conduction electron-emitting device in which the electron emission portion or its periphery is formed of a fine particle film, that is, the configuration of a vertical surface conduction electron-emitting device will be described.
[0113]
FIG. 10 is a schematic cross-sectional view for explaining the basic structure of a vertical type, in which 1201 is a substrate, 1202 and 1203 are element electrodes, 1206 is a step forming member, and 1204 is a conductive film using a fine particle film. 1205 is an electron emission portion formed by energization forming treatment, and 1213 is a thin film formed by energization activation treatment.
[0114]
The vertical type is different from the planar type described above in that one of the element electrodes (1202) is provided on the step forming member 1206, and the conductive thin film 1204 covers the side surface of the step forming member 1206. There is in point. 6 is set as the step height Ls of the step forming member 1206 in the vertical type. For the substrate 1201, the device electrodes 1202 and 1203, and the conductive thin film 1204 using a fine particle film, the materials listed in the description of the planar type can be used similarly. Further, the step forming member 1206 includes, for example, Si.O ₂An electrically insulating material such as
[0115]
Next, a method for manufacturing a vertical surface conduction electron-emitting device will be described. 11A to 11F are cross-sectional views for explaining the manufacturing process, and the notation of each member is the same as in FIG.
[0116]
1) First, as shown in FIG. 11A, an element electrode 1203 is formed on a substrate 1201.
[0117]
2) Next, as shown in FIG. 2B, an insulating layer for forming a step forming member is laminated. The insulating layer is, for example, SiO ₂ May be laminated by sputtering, but other film forming methods such as vacuum deposition and printing may be used.
[0118]
3) Next, as shown in FIG. 3C, the device electrode 1202 is formed on the insulating layer.
[0119]
4) Next, as shown in FIG. 4D, a part of the insulating layer is removed by using, for example, an etching method to expose the device electrode 1203.
[0120]
5) Next, as shown in FIG. 5E, a conductive thin film 1204 using a fine particle film is formed. For the formation, as in the case of the planar type, for example, a film forming technique such as a coating method may be used.
[0121]
6) Next, as in the case of the planar type, an energization forming process is performed to form an electron emission portion. (The same process as the planar energization forming process described with reference to FIG. 7C may be performed.)
7) Next, as in the case of the planar type, an energization activation process is performed to deposit carbon or a carbon compound in the vicinity of the electron emission portion. (The same process as the planar energization activation process described with reference to FIG. 7D may be performed.)
As described above, the vertical surface conduction electron-emitting device shown in FIG.
[0122]
(Characteristics of surface conduction electron-emitting devices used in display devices)
The device configuration and manufacturing method of the planar and vertical surface conduction electron-emitting devices have been described above. Next, the characteristics of the devices used in the display device will be described.
[0123]
FIG. 12 shows typical examples of (emission current Ie) vs. (element applied voltage Vf) characteristics and (element current If) vs. (element applied voltage Vf) characteristics of the elements used in the display device. The emission current Ie is remarkably smaller than the device current If and is difficult to show on the same scale, and these characteristics are changed by changing design parameters such as the size and shape of the device. Therefore, the two graphs are shown in arbitrary units.
[0124]
The element used in the display device has the following three characteristics with respect to the emission current Ie.
[0125]
First, when a voltage greater than a certain voltage (referred to as a threshold voltage Vth) is applied to the device, the emission current Ie increases rapidly. On the other hand, at a voltage lower than the threshold voltage Vth, the emission current Ie hardly Not detected.
[0126]
That is, it is a nonlinear element having a clear threshold voltage Vth with respect to the emission current Ie.
[0127]
Second, since the emission current Ie changes depending on the voltage Vf applied to the device, the magnitude of the emission current Ie can be controlled by the voltage Vf.
[0128]
Third, since the response speed of the current Ie emitted from the element is high with respect to the voltage Vf applied to the element, the amount of electrons emitted from the element can be controlled by the length of time for which the voltage Vf is applied.
[0129]
Because of the above characteristics, the surface conduction electron-emitting device could be suitably used for a display device. For example, in a display device in which a large number of elements are provided corresponding to the pixels of the display screen, display can be performed by sequentially scanning the display screen by using the first characteristic. That is, a voltage equal to or higher than the threshold voltage Vth is appropriately applied to the driven element according to the desired light emission luminance, and a voltage lower than the threshold voltage Vth is applied to the non-selected element. By sequentially switching the elements to be driven, it is possible to display by sequentially scanning the display screen.
[0130]
Further, by using the second characteristic or the third characteristic, the light emission luminance can be controlled, so that gradation display can be performed.
[0131]
(Structure of multi-electron beam source with simple matrix wiring of many elements)
Next, the structure of a multi-electron beam source in which the above-described surface conduction electron-emitting devices are arranged on a substrate and wired in a simple matrix will be described.
[0132]
FIG. 2 is a plan view of the multi-electron beam source used in the display panel of FIG. A surface conduction electron-emitting device similar to that shown in FIG. 1 is arranged on the substrate, and these devices are wired in a simple matrix by row-direction wiring electrodes 1013 and column-direction wiring electrodes 1014. An insulating layer (not shown) is formed between the electrodes at the intersecting portions of the row direction wiring electrodes 1013 and the column direction wiring electrodes 1014 so that electrical insulation is maintained.
[0133]
A cross section taken along the line BB 'of FIG. 2 is shown in FIG.
[0134]
In addition, the multi-electron source having such a structure has a row-direction wiring electrode 1013, a column-direction wiring electrode 1014, an interelectrode insulating layer (not shown), and element electrodes of the surface conduction electron-emitting device and conductivity on the substrate in advance. After the thin film was formed, each element was supplied with power through the row direction wiring electrode 1013 and the column direction wiring electrode 1014 to perform energization forming processing and energization activation processing.
[0135]
(Drive circuit configuration and drive method)
FIG. 13 is a block diagram showing a schematic configuration of a drive circuit for performing television display based on NTSC television signals. In the figure, a display panel 1701 corresponds to the display panel described above, and is manufactured and operated as described above. Further, the scanning circuit 1702 scans the display line, and the control circuit 1703 generates a signal and the like input to the scanning circuit. The shift register 1704 shifts the data for each line, and the line memory 1705 inputs the data for one line from the shift register 1704 to the modulation signal generator 1707. A synchronization signal separation circuit 1706 separates the synchronization signal from the NTSC signal.
[0136]
Hereinafter, functions of each part of the apparatus of FIG. 13 will be described in detail.
[0137]
First, the display panel 1701 is connected to an external electric circuit via terminals Dx1 to Dxm, terminals Dy1 to Dyn, and a high voltage terminal Hv. Among these, terminals Dx1 to Dxm sequentially drive a multi-electron beam source provided in the display panel 1701, that is, cold cathode devices arranged in a matrix of m rows and n columns, one row (n elements) at a time. Then, a scanning signal for applying is applied. On the other hand, a modulation signal for controlling output electron beams of n elements for one row selected by the scanning signal is applied to the terminals Dy1 to Dyn. The high voltage terminal Hv is supplied with a DC voltage of, for example, 5 [kV] from the DC voltage source Va, which is sufficient to excite the phosphor with the electron beam output from the multi-electron beam source. This is the acceleration voltage for applying energy.
[0138]
Next, the scanning circuit 1702 will be described. The circuit includes m switching elements (schematically shown by S1 to Sm in the drawing), and each switching element has an output voltage of a DC voltage source Vx or 0 [V] ( One of the ground levels is selected and electrically connected to the terminals Dx1 to Dxm of the display panel 1701. Each of the switching elements S1 to Sm operates based on the control signal Tscan output from the control circuit 1703. In practice, however, it can be easily configured by combining switching elements such as FETs. . The DC voltage source Vx outputs a constant voltage so that the drive voltage applied to the element not scanned based on the characteristics of the electron-emitting element illustrated in FIG. 118 is equal to or lower than the electron-emitting threshold voltage Vth voltage. It is set to do.
[0139]
The control circuit 1703 has a function of matching the operations of the respective units so that appropriate display is performed based on an image signal input from the outside. Based on a synchronization signal Tsync sent from a synchronization signal separation circuit 1706 described below, Tscan, Tsft, and Tmry control signals are generated for each unit. The synchronization signal separation circuit 1706 is a circuit for separating the synchronization signal component and the luminance signal component from the NTSC system television signal input from the outside. As is well known, a frequency separation (filter) circuit is used. Can be easily configured. The synchronization signal separated by the synchronization signal separation circuit 1706 is composed of a vertical synchronization signal and a horizontal synchronization signal as is well known, but is shown here as a Tsync signal for convenience of explanation. On the other hand, the luminance signal component of the image separated from the television signal is represented as a DATA signal for convenience, and this signal is input to the shift register 1704.
[0140]
The shift register 1704 is for serial / parallel conversion of the DATA signal serially input in time series for each line of the image, and operates based on the control signal Tsft sent from the control circuit 1703. . In other words, the control signal Tsft can be rephrased as a shift clock of the shift register 1704. Data for one line (corresponding to driving data for n electron-emitting devices) subjected to serial / parallel conversion is output from the shift register 1704 as n signals Id1 to Idn.
[0141]
The line memory 1705 is a storage device for storing data for one line of an image for a necessary time, and appropriately stores the contents of Id1 to Idn according to a control signal Tmry sent from the control circuit 1703. The stored contents are output as I′d1 to I′dn and input to the modulation signal generator 1707.
[0142]
The modulation signal generator 1707 is a signal source for appropriately driving and modulating each of the electron-emitting devices 1015 in accordance with each of the image data I′d1 to I′dn, and the output signals thereof are terminals Doy1 to Doyn. And applied to the electron-emitting device 1015 in the display panel 1701.
[0143]
As described with reference to FIG. 12, the surface conduction electron-emitting device according to the present invention has the following basic characteristics with respect to the emission current Ie. That is, there is a clear threshold voltage Vth (8 [V] in the case of a surface conduction electron-emitting device of an example described later) for electron emission, and electron emission occurs only when a voltage higher than the threshold Vth is applied. Further, for a voltage equal to or higher than the electron emission threshold, the emission current Ie also changes according to the voltage change as shown in the graph of FIG. For this reason, when a pulsed voltage is applied to the element, for example, no electron emission occurs even when a voltage equal to or lower than the electron emission threshold Vth is applied. An electron beam is output from the conduction electron-emitting device. 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.
[0144]
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 in accordance with the input signal. When implementing the voltage modulation method, a voltage modulation method circuit is used as the modulation signal generator 1707, 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. Further, when implementing the pulse width modulation method, the modulation signal generator 1707 generates a pulse pulse having a constant peak value, and appropriately modulates the width of the voltage pulse according to the input data. A circuit of the type can be used.
[0145]
The shift register 1704 and the line memory 1705 can be either a digital signal type or an analog signal type. That is, it is only necessary to perform serial / parallel conversion and storage of the image signal at a predetermined speed.
[0146]
When the digital signal system is used, it is necessary to convert the output signal DATA of the synchronization signal separation circuit 1706 into a digital signal. For this purpose, an A / D converter may be provided at the output portion of the synchronization signal separation circuit 1706. . In this connection, the circuit used for the modulation signal generator is slightly different depending on whether the output signal of the line memory 115 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 1707, and an amplifier circuit or the like is added as necessary. In the case of the pulse width modulation method, a modulation signal generator 1707 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 to the driving voltage of the electron-emitting device can be added.
[0147]
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 1707, and a shift level 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 (VOC) can be adopted, and an amplifier for amplifying the voltage up to the driving voltage of the electron-emitting device can be added as necessary.
[0148]
In the image display apparatus to which the present invention can be applied, electron emission is generated by applying a voltage to each electron-emitting device via the external terminals Dox1 to Doxm and Doy1 to Doyn. A high voltage is applied to the metal back 1019 or transparent electrode (not shown) via the high voltage terminal Hv to accelerate the electron beam. The accelerated electrons collide with the fluorescent film 1018, and light is emitted to form an image.
[0149]
The configuration of the image display 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 idea of the present invention. The NTSC system is used as the input signal. However, the input signal is not limited to this, and other than the PAL and SECAM systems, the TV signal (high quality TV including the MUSE system) composed of a larger number of scanning lines than these. Can also be adopted.
[0150]
In the image display device of the present invention, a spacer for atmospheric pressure resistance is arranged in the display panel. As many spacers as necessary are arranged in the image display area and outside the area as needed.
[0151]
FIG. 14 is a cross-sectional view taken along the line AA ′ of the image forming apparatus of FIG. 1, and shows potential regulating portions of the spacer A (1020A), the spacer B (1020B), the spacer C (1020C), the face plate, and the rear plate.
[0152]
Therefore, the spacers A, B, and C arranged in the panel will be described.
[0153]
The spacer A in the image display region is provided with conductivity to withstand a high voltage applied between the metal back 1019 of the face plate 107 and the rear plate substrate 1011 and to prevent the surface of the spacer 1020 from being charged. To do.
[0154]
On the other hand, the spacer C outside the image area has a higher resistance than the spacer in the image area. In the region not affected by charging, it is not necessary to relax charging, and an insulating spacer C is used to suppress leakage current.
[0155]
In addition, the spacer B arranged outside the image display area in the range affected by charging imparts conductivity to the surface of the spacer. If the distance between the face plate 1017 and the rear plate substrate 1011 is d, it is easily affected by charging in the range of the distance 2d outside the image display area. Therefore, a conductive spacer for preventing charging is disposed. To do.
[0156]
In that case, the potential is regulated in a range where the spacers having conductivity are arranged. The potential regulating portion 2000 of the face plate 1017 has the same potential as the ITO thin film on the surface, metal back, and the like. In the rear plate substrate 1011, the potential of the row direction wiring 1013, the potential of the column direction wiring, or the potential of the column direction wiring 1013 is regulated by the row direction wiring 1013, the column direction wiring 1014, or another independent wiring.
[0157]
Next, the range 2d that defines the potential will be described with reference to FIG.
[0158]
A potential difference applied to the metal back 1019 or the ITO thin film and the rear plate substrate 1011 is Va, and an interval is d. A part of the electrons emitted from the electron source is reflected by the phosphor, or a cation is emitted from the phosphor, and is irradiated to the nearby spacer, phosphor, and electron source substrate. When the electrons reflected by the phosphor have an energy of Va (e is the charge possessed by the electrons), the region that scatters to the periphery after reflection is in the range of 2d from the reflection position of the phosphor. In that range, charging occurs when the irradiated member is insulating.
[0159]
A high resistance film was applied to the member arranged in that region to prevent charging.
[0160]
However, since the influence of charging is small outside 2d, an insulating spacer C was used to suppress unnecessary leakage current.
[0161]
【Example】
[Example]
FIG. 16 shows an image forming apparatus of the present invention.Examples ofFIG. 17 is a diagram schematically showing a cross section (AA ′) viewed from the image forming apparatus Y direction shown in FIG. 16. 16 and 17, an electron source (E13) in which a plurality of surface conduction electron-emitting devices (E12) are arranged on a matrix is fixed to the rear plate (E11). In the electron source (E13), a face plate (E17) as an image forming member in which a fluorescent film (E15) and a metal back (E16) as an acceleration electrode are formed on the inner surface of a glass substrate (E14) is made of an insulating material. A high voltage is applied between the electron source (E13) and the metal back (E16) by a power source (not shown). The rear plate (E11), the support frame (E18), and the face plate (E17) constitute an envelope.
[0162]
As shown in FIG. 15, the distance between the metal back (E16) and the electron source (E13) is d, and the range in which the electrons emitted from the electron source are incident on the face plate is A. A configuration in which the spacer A (E19A) arranged in the range of A, the spacer B (E19B) arranged in the range from the outline to 2d outside, and the spacer C (E19C) arranged further outside will be described.
[0163]
The spacers (E19A, E19B) are imparted with conductivity on the surface to suppress charging. As a conductive film (E111) on the surface, SiO ₂ Was deposited by evaporation to a thickness of about 1000 mm. The size of the surface resistance is 1.0 × 10¹⁰(Ω / □).
[0164]
Further, a potential regulating film made of a metal film is formed on the surface of the electron source (E13) in a predetermined range (E112) of a portion excluding each electron-emitting device (E12) and a wiring electrically connecting them. The range is the potential regulating portion. In the present example, a Pt sputtered film was formed by depositing 2000 mm. This potential regulating film may be formed only in the electron source proximity region (the outer periphery of the electron source).
[0165]
Further, a film such as an ITO film (E110) and a metal back (E16) is formed outside the region where the image of the face plate (E17) is displayed, and the potential is regulated. In this example, ITO (E110) was used for potential regulation.
[0166]
In addition, the spacer C arrange | positioned in the area | region where electric potential is not defined used the insulating member.
[0167]
In this embodiment, d is 5 mm. That is, the potential-defined region B is a range of about 10 mm outward from the image display region in each of the X direction and the Y direction. At the time of image display, 6 kV was applied between the face plate (E17) and the rear plate (E11). The voltage for driving the element was 15V.
[0168]
Electrons emitted from the electron-emitting device (E12) are reflected by the face plate (E17) and enter the spacers A and B. On the spacer surface, incident electrons cause secondary electron emission and charging occurs. However, a minute current flows through the conductive films on the surfaces of the spacers A and B through the potential-regulated films of the face plate (E17) and the rear plate (E11), so that charging can be alleviated.
[0169]
In addition, since charging that occurs in the spacers A and B when the element is driven does not occur in the spacer C, the material can be made insulative and leakage current can be suppressed.
[0170]
As a result, the electrons emitted from the electron source are minimized by the effects of charging, the electron trajectory is stable, a good image with no displacement of the light emission position is formed, and leakage occurs with spacers that are not affected by charging. It has become possible to reduce power consumption by suppressing current.
[0171]
In this embodiment, the surface resistances of the spacers A and B are set to be the same, but different resistance values may be used. In particular, the power consumption can be further suppressed by making the spacer B have a higher resistance than A.
[0172]
[Reference example]
BookReference exampleThen, although a spacer is arrange | positioned in an image display area, it demonstrates by the structure by which a spacer is not arrange | positioned in the periphery vicinity of a display area. Spacers are arranged at remote locations outside the display area.
[0173]
FIG. 18 shows an image forming apparatus according to the present invention.Reference exampleFIG. 19 is a diagram schematically showing a cross section (AA ′) viewed from the image forming apparatus Y direction shown in FIG. 18. In FIG. 19, an electron source (E23) in which a plurality of surface conduction electron-emitting devices (E22) are arranged on a matrix is fixed to the rear plate (E21). In the electron source (E23), a face plate (E27) as an image forming member in which a fluorescent film (E25) and a metal back (E26) as an acceleration electrode are formed on the inner surface of a glass substrate (E24) is made of an insulating material. A high voltage is applied between the electron source (E23) and the metal back (E26) by a power source (not shown). The rear plate (E21), the support frame (E28), and the face plate (E27) constitute an envelope.
[0174]
A range in which electrons emitted from the electron source are incident on the face plate is A. A configuration in which the spacer A (E29A) arranged in the range of A and the spacer C (E29C) arranged outside thereof will be described.
[0175]
The spacer disposed in this region is provided with a conductive film (E111) on the surface to impart conductivity and suppress charging. Si on the surfaceO ₂ Was deposited by evaporation to a thickness of about 1000 mm. The size of the surface resistance is 1.0 × 10¹⁰(Ω / □).
[0176]
On the other hand, the spacer arrange | positioned out of the image display area used the insulating member.
[0177]
In this embodiment, d is 5 mm. At the time of image display, 6 kV was applied between the face plate and the rear plate. The voltage for driving the element was 15V.
[0178]
In the image display area, when charging occurs on the surface of the spacer during image display, a minute current flows through the spacer surface through the potential-regulated films of the face plate and the rear plate, and the charging can be relaxed. Outside the image region, the leakage current can be suppressed by insulating the spacer.
[0179]
【The invention's effect】
According to the present invention described above, it is possible to provide an image forming apparatus with low leakage current and low power consumption while suppressing the image quality deterioration due to the charging of the spacers in the image area while forming a good image.
[Brief description of the drawings]
FIG. 1 is a perspective view of a display panel provided in an image forming apparatus of the present invention.
2 is a plan view of a multi-electron beam source used in the display panel of FIG.
3 is a cross-sectional view of the multi-electron beam source of FIG. 2 along BB ′.
FIG. 4 is a layout diagram of phosphors.
[Fig. 5] Enlarged view of spacer
FIG. 6 is a plan view and a cross-sectional view of a planar surface conduction electron-emitting device.
FIG. 7 is a manufacturing process diagram of a planar surface conduction electron-emitting device.
FIG. 8 is a waveform diagram of the forming voltage.
FIG. 9 is a waveform diagram of an output voltage from a power supply for activation processing.
FIG. 10 is a sectional view of a vertical surface conduction electron-emitting device.
FIG. 11 is a manufacturing process diagram of a vertical surface conduction electron-emitting device.
FIG. 12 is a graph showing typical characteristics of the surface conduction electron-emitting device used in the examples.
FIG. 13 shows a driving circuit for performing television display.
14 is a diagram of the image forming apparatus of FIG.A-A 'Sectional view along
FIG. 15 is an enlarged cross-sectional view in the vicinity of an electron-emitting device for explaining a range defining a potential
FIG. 16ExamplePerspective view
17 is the same as FIG.ExampleSectional view along AA '
FIG. 18Reference examplePerspective view
19 is the same as FIG.Reference exampleSectional view along AA '
FIG. 20 is a plan view of a conventional surface conduction electron-emitting device.
FIG. 21 is a sectional view of a conventional field emission device.
FIG. 22 is a sectional view of a conventional metal / insulating layer / metal-type electron-emitting device.
FIG. 23 is a perspective view of a conventional flat display panel.
[Explanation of symbols]
1 Insulating material
3 Contact surface
5 Sides
11 High resistance film
21 Low resistance film
22 Convex
31 Boundary membrane
1010 Black conductor
1011 substrate
1012 Cold cathode device
1013 Row direction wiring
1014 Wiring in column direction
1015 Rear plate
1016 side wall
1017 Face plate
1018 Fluorescent film
1019 Metal back
1020 Spacer
1101 substrate
1102, 1103 Device electrode
1104 Conductive thin film
1105 Electron emission unit
1110 Power supply for forming
1111 Ammeter
1112 Power supply for activation
1113 Thin film formed by energization activation process
1114 Anode electrode
1115 DC high voltage power supply
1116 Ammeter
1201 substrate
1202, 1203 Device electrode
1204 conductive thin film
1205 electron emitter
1206 Step forming member
1213 Thin film formed by energization activation treatment
1701 Display panel
1702 Scanning circuit
1703 Control circuit
1704 Shift register
1705 line memory
1706 Sync signal separation circuit
1707 Modulation signal generator
3001 Substrate
3004 Conductive thin film
3005 Electron emitter
3010 substrate
3011 Emitter wiring
3012 Emitter cone
3013 Insulating layer
3014 Gate electrode
3020 substrate
3021 Lower electrode
3022 Insulating layer
3023 Upper electrode
3111 substrate
3112 Cold cathode element
3113 Row direction wiring
3114 Column wiring
3115 Rear plate
3116 side wall
3117 face plate
3118 phosphor film
3119 metal back
3120 Spacer

Claims (6)

A rear plate having an electron source region where the electron source is arranged to have an electron-emitting device, in order to irradiate the electrons emitted from the electron source, disposed opposite in a vacuum atmosphere to the electron source, the electron-emitting devices A face plate having an irradiation member region in which an electron irradiation member to which an acceleration voltage for accelerating electrons emitted from the electron beam is applied is disposed, and a support frame disposed between the rear plate and the face plate. In an image forming apparatus having an envelope provided, and a plurality of spacers arranged inside the envelope ,
Of the plurality of spacers, if the distance between the rear plate and the face plate is d, the electron source region and the adjacent region in the range of 2d from the outer periphery of the electron source region, or the irradiation member region and the An image forming apparatus , wherein a spacer disposed in an adjacent region within a range of 2d from the outer periphery of the irradiation member region is conductive, and a spacer disposed in a region other than the region is insulative . It said adjacent region of the outer circumference in the range of 2d of the irradiated member region, the image forming apparatus according to claim 1, wherein Tei Rukoto defined in the potential of the electron irradiation member. Flanking region ranging from the outer periphery 2d of the electron source region, the image forming apparatus according to claim 1, wherein the Ru Tei defined in the potential of the electron source. Flanking region ranging from the outer periphery 2d of the electron source region, the image forming apparatus according to claim 1, wherein that you have specified in the potential of the wiring for driving the electron source. Flanking region ranging from the outer periphery 2d of the electron source region, the image forming apparatus according to claim 1, Rukoto wherein is defined at zero potential by another wire other than the wiring for driving the electron source. The spacer disposed in the adjacent region in which the surface resistance of the spacer in the irradiation member region or the electron source region is in the range of 2d from the outer periphery of the irradiation member region or in the adjacent region in the range of 2d from the outer periphery of the electron source region The image forming apparatus according to claim 1 , wherein the image forming apparatus has a surface resistance lower than that of the image forming apparatus.

Images