JP3619043B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus, and more particularly to a flat image forming apparatus that suppresses discharge of a spacer of a vacuum envelope in which a plurality of electron-emitting devices are arranged.
[0002]
[Prior art]
Since the flat display device is thin and lightweight, it has attracted attention as a replacement for a cathode ray tube display device. In particular, a display device using a combination of an electron-emitting device and a phosphor that emits light when irradiated with an electron beam is expected to have characteristics superior to those of other conventional 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 become widespread in recent years.
[0003]
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.
[0004]
Examples of the surface conduction electron-emitting device include M.I. I. Elinson, Radio Eng. Electron Phys. , 10, 1290, (1965).
[0005]
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 the surface conduction electron-emitting device, in addition to the SnO2 thin film by Erinson et al. Dittmer: “Thin Solid Films”, 9, 317 (1972)], or an In 2 O 3 / SnO 2 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.
[0006]
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.
[0007]
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.
[0008]
An example of the FE type is 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 molecondens cones”, J. Am. Appl. Phys. 47, 5248 (1976).
[0009]
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.
[0010]
Further, as another element configuration of the FE type, there is an example in which an emitter and a gate electrode are arranged on the substrate substantially parallel to the substrate plane, instead of the laminated structure as shown in FIG.
[0011]
Examples of the MIM type include C.I. A. Mead, “Operation of tunnel-emission Devices, J. Appl. Phys., 32, 646 (1961), etc. A typical example of an MIM type device configuration is shown in FIG. In the figure, 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 an upper electrode made of a metal having a thickness of about 80 to 300 angstroms.
[0012]
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.
[0013]
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.
[0014]
For this reason, research for applying cold cathode devices has been actively conducted.
[0015]
For example, the surface conduction electron-emitting device has an advantage that a large number of devices can be formed over a large area because the structure is particularly simple and easy to manufacture among the 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.
[0016]
As for the application of surface conduction electron-emitting devices, for example, image forming apparatuses such as image forming apparatuses and image recording apparatuses, charged beam sources, and the like have been studied.
[0017]
In particular, as an application to an image forming apparatus, for example, as disclosed in US Pat. No. 5,066,883 and Japanese Patent Application Laid-Open No. 2-257551 and Japanese Patent Application Laid-Open No. 4-28137 by the present applicant, surface conduction electron emission. An image forming apparatus using a combination of an element and a phosphor that emits light when irradiated with an electron beam has been studied. An image forming apparatus 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 forming apparatuses. 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 become widespread in recent years.
[0018]
A method for driving a plurality of FE types in a row is disclosed in, for example, USP 4,904,895 by the present applicant. As an example of applying the FE type to an image forming apparatus, 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 Microelectronics Conf. , Nagahama, pp. 6-9 (1991)]
An example in which a large number of MIM types are arranged and applied to an image forming apparatus is disclosed in, for example, Japanese Patent Laid-Open No. 3-55738 by the present applicant.
[0019]
FIG. 21 is a perspective view showing an example of a display panel unit constituting a flat type image forming apparatus, and a part of the panel is cut away to show the internal structure.
[0020]
In the figure, reference numeral 3115 denotes a rear plate, 3116 denotes a side wall, and 3117 denotes 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. It is appropriately set according to the number of display pixels to be performed). The N × M cold cathode elements 3112 are wired by m row-directional wirings 3113 and n column-directional wirings 3114, as shown in FIG. 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, 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 forming apparatus increases, the rear plate 3115 and the face plate due to the pressure difference 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 3117 not only increases the weight of the image forming apparatus, but also causes image distortion and parallax when viewed from an oblique direction.
[0025]
On the other hand, in FIG. 21, a structural support (called a spacer or a rib) 3120 made of a relatively thin glass plate for 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 3117 on which the fluorescent film 3118 is formed is normally maintained at sub millimeters to several millimeters, and the inside of the hermetic container is maintained at a high vacuum as described above. ing.
[0026]
The image forming apparatus using the display panel described above emits electrons from each cold cathode element 3112 when a voltage is applied to each cold cathode element 3112 through the container 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 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.
[0027]
However, the display panel of the conventional image forming apparatus described above has the following problems.
[0028]
First, there is a possibility that spacer charging is caused by a part of electrons emitted from the vicinity of the spacer 3120 hitting the spacer 3120 or ions ionized by the action of emitted electrons adhere to the spacer. Furthermore, a part of the electrons that have reached the face plate are reflected and scattered, and a part of the electrons may hit the spacer, thereby causing spacer charging. The electrons emitted from the cold cathode element 3112 due to the charging of the spacer are bent in the trajectory, reach a place different from the normal position on the phosphor, and the image near the spacer is distorted and displayed.
[0029]
Second, a high voltage of several hundred volts or higher (that is, a high electric field of 1 kV / mm or more) is applied between the multi-electron beam source and the face plate 3117 in order to accelerate electrons emitted from the cold cathode device 3112. Therefore, there is a concern about creeping discharge on the surface of the spacer 3120. In particular, when the spacer is charged as described above, discharge may be induced.
[0030]
In order to solve this problem, the present applicant has proposed to remove the charge so that a minute current flows through the spacer (Japanese Patent Laid-Open Nos. 8-180821 and 8-250032). In this case, a high resistance thin film is formed on the surface of the insulating spacer so that a minute current flows on the surface of the spacer. The high resistance film used here is tin oxide, or a mixed crystal thin film of tin oxide and indium oxide, an island-shaped metal film, or the like.
[0031]
Further, in the above proposal by the present applicant, there is also a configuration in which a low resistance film is formed at the connection portion in order to electrically connect the spacer coated with the high resistance film to the multi-electron beam source and the face plate. It is disclosed. Further, a configuration is disclosed in which the spacer coated with the high resistance film and the low resistance film is electrically connected and mechanically fixed to the multi electron beam source and the face plate by using conductive frit glass. Yes.
[0032]
[Problems to be solved by the invention]
However, when the spacer having the high resistance film and the low resistance film is used as in the prior art, the electric fields generated on the surface of the high resistance film portion and the low resistance film portion are different from each other. An electric field jump occurs. In such a transition region, when a unique shape such as a protrusion is generated due to a defect in the manufacturing process, electric field concentration is likely to occur, causing discharge.
[0033]
Therefore, the present invention provides an image forming apparatus using a spacer having a high resistance film on the surface and a low resistance film at a connection portion between the multi-electron beam source and the face plate. It is an object of the present invention to provide a spacer structure that suppresses unexpected electric field concentration at the boundary and prevents discharge. It is another object of the present invention to provide a highly reliable image forming apparatus using the above means.
[0034]
[Means for Solving the Problems]
The present invention for solving the above problems forms an image by collision of an electron source having a cold cathode element, an electrode for controlling electrons emitted from the electron source, and electrons emitted from the electron source. In the image forming apparatus having an image forming member, and a spacer disposed between the electron source and the electrode, the spacer has a high resistance film on a surface, and the spacer with respect to the electron source and the electrode The contact portion has a low resistance film, and the high resistance film is electrically connected to the electron source and the electrode through the low resistance film, and the spacer Between the low resistance film and the high resistance film Further, from the low resistance film to the high resistance film From low resistance to high resistance And the resistance value changes continuously boundary An area is provided.
[0035]
That is, in the present invention, by providing a region where the resistance value continuously changes at the boundary between the high resistance film and the low resistance film, the electric field concentration is caused by the convex portion of the low resistance film boundary line generated in the manufacturing process. Has eased.
[0036]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0037]
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. In the figure, reference numeral 1015 denotes a rear plate, 1016 denotes a side wall, and 1017 denotes a face plate. The rear plate 1015, the side wall 1016, and the face plate 1017 form an envelope (airtight container) for maintaining the inside of the display panel in a vacuum. Forming. In addition, a spacer 1020 for supporting atmospheric pressure is provided inside the airtight container. The spacer used in this embodiment is a flat plate.
[0038]
A substrate 1011 is fixed to the rear plate 1015, and n × m cold cathode elements 1012 are formed on the substrate 1011, and m row direction (X direction) wirings 1013 and n columns are formed. Wired by direction (Y direction) wiring 1014.
[0039]
A fluorescent film 1018 is formed on the lower surface of the face plate 1017, and a metal back 1019 made of Al or the like is formed on the surface of the fluorescent film 1018 on the rear plate 1015 side.
[0040]
FIG. 2 is a schematic diagram of the AA ′ cross section of FIG. FIG. 3 is a schematic view of the spacer 1020 as seen from the direction of the flat plate surface, and the apparatus configuration in the vicinity thereof is also shown. The numbers in FIG. 2 and FIG. 3 correspond to those in FIG.
[0041]
In FIG. 2, a spacer 1020 forms a high-resistance film 11 on the surface of a thin plate-like insulating member 1, and is provided inside the face plate 1017 (metal back 1019) and on the surface of the substrate 1011 (row-directional wiring 1013). It consists of the member which formed the low resistance film | membrane 21 into the contact part 3 of the spacer which faced, and the side part 5 which contact | connects the contact surface 3. As shown in FIG. The thin plate-like spacers 1020 are arranged along the row direction (X direction) and are fixed on the row direction wirings 1013 of the substrate 1011 via the bonding material 1041. The high resistance film 11 is electrically connected to the row direction wiring 1013 via the low resistance film 22 and the bonding material 1041 on the substrate 1011 side, and is metal-backed by pressure contact via the low resistance film 22 on the face plate 1017 side. 1019 is electrically connected.
[0042]
In FIG. 3, a boundary film 31 whose resistance value changes continuously (or stepwise) is provided in the boundary region between the high resistance film 11 and the low resistance film 21.
[0043]
Suitable methods for forming the boundary film 31 include vacuum film formation such as sputtering or ion implantation using a movable mask, application by ink jet or printing, diffusion by heat treatment, and the like.
[0044]
The sheet resistance value of the boundary film 31 matches the sheet resistance value of the high resistance film 11 on the side in contact with the high resistance film 11, and the sheet resistance value of the low resistance film 21 on the side in contact with the low resistance film 21. The width W of the region formed by the boundary film 31 is approximately 50 μm or less.
[0045]
FIG. 4 is a diagram illustrating a case where a protrusion is generated on the low resistance film boundary line in the manufacturing process. In the figure, reference numeral 22 denotes a convex portion in the boundary region of the low resistance film 21, and its shape is represented by a height h and a width w.
[0046]
The degree of electric field concentration when such a convex shape occurs is shown in FIG. Here, the case where there is no convex portion 22 is set to 1. In FIG. 5, when the ratio of the height h to the width w of the convex shape is 1 or less, the electric field concentration does not increase rapidly even if the height ratio increases, and is about 3 times at the maximum. On the other hand, since the ratio of the height h to the convex width w exceeds 2, the electric field concentration increases rapidly as the height ratio increases. Therefore, it is preferable to control the spacer fabrication / assembly process so that the height-to-width ratio (h / w) is 2 or less even when the convex portion 22 is generated in the boundary region of the low resistance film 21.
[0047]
Further, in the embodiment of the present invention shown in FIGS. 1 and 2, a boundary film 31 whose resistance value changes continuously (or stepwise) is provided in the boundary region between the high resistance film 11 and the low resistance film 21. However, it is a further preferable condition to control the spacer fabrication / assembly process so that the convex portion 22 of the low resistance film 21 does not extend beyond the boundary film 31 to the region of the high resistance film 11. Thereby, the electric field concentration in the convex part 22 is further eased.
[0048]
The region width s of the boundary film 31 depends on how high the convex portion 22 having the height h is generated, which depends on the spacer manufacturing process. However, in the case of using vacuum film formation by a mask method, film formation by a printing method, or the like, a normal process can sufficiently suppress the height of the convex portion 22 to 10 μm to 20 μm. Therefore, the region width s of the boundary film 31 is preferably larger than about 10 μm.
[0049]
On the other hand, as will be described later, a part of the low resistance film 21 and the boundary film 31 affects the electron trajectory emitted from the electron-emitting device in the vicinity of the spacer and changes the arrival point to the face plate. The tolerance for the change of the arrival point depends on the resolution of the image to be formed, but is about 10 μm to 100 μm. For example, in a 60-inch diagonal (16: 9 aspect ratio) image forming apparatus, when high-quality display (1000 or more scanning lines) is performed, the width of one scanning line is about 800 μm, but about 5% is reached. The tolerance for the change is 40 μm. From the above, the region width s of the boundary film 31 is preferably about 100 μm or less.
[0050]
Next, the configuration and manufacturing method of the display panel of the image forming apparatus to which the present invention is applied will be described with specific examples.
[0051]
FIG. 1 is a perspective view of a display panel used in the embodiment, and a part of the panel is cut away to show the internal structure.
[0052]
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. Sealing was achieved by baking at 400 to 500 degrees for 10 minutes or more. A method of 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.
[0053]
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 intended. For example, in a display device intended for display of a high-definition television, it is desirable to set N = 3000 and M = 1000 or more. The N × M cold cathode elements are simply matrix-wired by M row-directional wirings 1013 and N column-directional wirings 1014. The part constituted by 1011 to 1014 is called a multi-electron beam source.
[0054]
The multi-electron beam source used in the image forming 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.
[0055]
Next, the structure of a multi-electron beam source in which surface conduction electron-emitting devices (described later) are arranged as a cold cathode device on a substrate and wired in a simple matrix will be described.
[0056]
FIG. 6 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 similar to those shown in FIG. 102 described later are arranged, 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.
[0057]
FIG. 7 shows a cross section taken along the line BB ′ of FIG.
[0058]
Note that the multi-electron source having such a structure has a row-direction wiring electrode 1013, a column-direction wiring electrode 1014, an inter-electrode insulating layer (not shown), and element electrodes of a surface-conduction electron-emitting device and conductivity on a substrate in advance. After the thin film was formed, each element was supplied through the row direction wiring electrode 1013 and the column direction wiring electrode 1014 to perform energization forming processing (described later) and energization activation processing (described later).
[0059]
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.
[0060]
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.
[0061]
For example, as shown in FIG. 8A, 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, and to prevent the reflection of external light and prevent a decrease in display contrast. This is to prevent the fluorescent 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.
[0062]
In addition, the method of separately applying the phosphors of the three primary colors is not limited to the stripe arrangement shown in FIG. 8A, and for example, a delta arrangement as shown in FIG. It may be an array. For example, as shown in FIG. 9, the black conductors 1010 are provided not only between the stripe-shaped phosphors but also in the orthogonal stripe directions, and are separately arranged so as to separate the pixels in both directions of the matrix. It may be.
[0063]
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.
[0064]
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 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.
[0065]
Although not used in this embodiment, a transparent electrode made of, for example, ITO is provided between the face plate substrate 1017 and the fluorescent film 1018 for the purpose of applying an acceleration voltage and improving the conductivity of the fluorescent film. May be.
[0066]
In the embodiment of the present invention, the fluorescent film 1018 having the arrangement shown in FIG. 9 is used, and the respective color phosphors are arranged so as to extend in the column direction (Y direction). The spacer 1020 was arranged in parallel to the rear of the row (X direction) in a region corresponding to the black conductor 1010 via a metal back 1019 (described later).
[0067]
Note that when performing the above-described sealing, each color phosphor disposed on the face plate 1017 must correspond to each element 1012 disposed on the substrate 1011. Therefore, the rear plate 1015, the face plate 1017 and the spacer 1020 were sufficiently aligned.
[0068]
FIG. 2 is a schematic cross-sectional view taken along the line AA ′ of FIG. 1, and the numbers of the respective parts correspond to those of FIG. The spacer 1020 forms a high-resistance film 11 for the purpose of 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 by 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 airtight container, and the high resistance film is interposed through the low resistance film 21 on the spacer 1020 and the bonding material 1041. 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.
[0069]
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.
[0070]
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.
[0071]
A current obtained by dividing the acceleration voltage Va applied to the face plate 1017 (metal back 1019 or the like) on the high potential side by the resistance value Rs of the high resistance film 11 flows through the high resistance film 11 constituting the spacer 1020. Therefore, the resistance value Rs of the spacer is set in a desirable range from antistatic and power consumption. Surface resistance R / □ is 10 from the viewpoint of antistatic ¹² It is preferable that it is below Ω / □. 10 to obtain sufficient antistatic effect ¹¹ More preferably less than Ω / □. The lower limit of the surface resistance depends on the spacer shape and the voltage applied between the spacers. ⁵ It is preferable that it is Ω / □ or more.
[0072]
The thickness t of the high resistance film 11 formed on the insulating member 1 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, generally a thin film of 10 nm or less is 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. From the preferable range of R / □ and t described above, the specific resistance ρ of the high resistance film 11 is 0.1 [Ωcm] to 10 8 [Ωcm]. preferable. 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.
[0073]
As described above, the temperature of the spacer rises when a current flows through the high resistance film 11 formed thereon or when the entire display generates heat during operation. When the temperature coefficient of resistance of the high resistance film 11 is a large negative value, the resistance value decreases when the temperature rises, the current flowing through the spacer increases, and the temperature rises. 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 temperature coefficient of resistance of the high resistance film 11 is desirably less than −1%.
[0074]
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.
[0075]
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.
[0076]
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.
[0077]
The low resistance film 21 constituting the spacer 1020 electrically connects the high resistance film 11 to the high potential side face plate 1017 (metal back 1019 and the like) and the low potential side substrate 1011 (wirings 1013 and 1014 and the like). 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.
[0078]
(1) The high resistance film 11 is electrically connected to the face plate 1017 and the substrate 1011.
[0079]
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, etc.) directly or via the contact member 1041, or a large contact resistance is generated at the interface of the connection portion, and there is a possibility that charges 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.
[0080]
(2) The potential distribution of the high resistance film 11 is made uniform.
[0081]
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.
[0082]
(3) Control the orbit of emitted electrons.
[0083]
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.
[0084]
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. Appropriately from alloys, printed conductors composed of metals such as Pd, Ag, Au, RuO2, Pd-Ag, metal oxides and glass, transparent conductors such as In2O3-SnO2, and semiconductor materials such as polysilicon Selected.
[0085]
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.
[0086]
Dx1 to Dxm, 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 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.
[0087]
Further, in order to evacuate the inside of the hermetic container, after assembling the hermetic container, an exhaust pipe (not shown) and a vacuum pump are connected, and the inside of the hermetic container is ^-7 Exhaust to a vacuum level of about Torr. 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. A 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 an airtight container is 1 × 10 6 by the adsorption action of the getter film. ^-5 Or 1 × 10 ^-7 The Torr vacuum is maintained.
[0088]
In the image forming apparatus using the display panel described above, when a voltage is applied to each cold cathode element 1012 through the external terminals Dx1 to Dxm and Dy1 to Dyn, electrons are emitted from each cold cathode element 1012. 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.
[0089]
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].
[0090]
The basic configuration and manufacturing method of the display panel of the embodiment of the present invention and the outline of the image forming apparatus have been described above. Next, a method for manufacturing a multi-electron beam source used for the display panel of the embodiment will be described. The multi-electron beam source used in the image forming 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.
[0091]
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 an image forming apparatus having a high luminance and a large screen. 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.
[0092]
First, the basic structure, 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.
[0093]
(Suitable device structure and manufacturing method of surface conduction electron-emitting device)
As a typical configuration of a surface conduction electron-emitting device in which an electron emitting portion or a peripheral portion thereof is formed from a fine particle film, there are two types, a planar type and a vertical type.
[0094]
(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. FIG. 10 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.
[0095]
As the substrate 1101, for example, various glass substrates including quartz glass and blue plate glass, various ceramic substrates including alumina, or a substrate obtained by laminating an insulating layer made of, for example, SiO2 on the various substrates described above, Etc. can be used.
[0096]
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, and Ag, alloys of these metals, metal oxides including In2O3-SnO2, and polysilicon A material may be appropriately selected and used from semiconductors such as. In order to form an 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. However, the electrode can be formed using other methods (for example, a printing technique). No problem.
[0097]
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.
[0098]
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.
[0099]
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.
[0100]
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. Metals, oxides including PdO, SnO2, In2O3, PbO, Sb2O3, borides such as HfB2, ZrB2, LaB6, CeB6, YB4, GdB4, TiC, ZrC, HfC , TaC, SiC, WC, and other carbides, TiN, ZrN, HfN, and other nitrides, Si, Ge, and other semiconductors, carbon, etc. Selected.
[0101]
As described above, the conductive thin film 1104 is formed of a fine particle film. ³ Ω / □ to 10 ⁷ It was set to be included in the range of Ω / □.
[0102]
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 have a structure in which a part of each other overlaps. In the example of FIG. 102, 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.
[0103]
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 emission portion, it is schematically shown in FIG.
[0104]
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.
[0105]
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.
[0106]
Although the preferred element substrate structure has been described above, the following elements were used in the examples.
[0107]
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].
[0108]
Pd or PdO was used as the 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].
[0109]
Next, a preferred method for manufacturing a planar surface conduction electron-emitting device will be described.
[0110]
11A to 11D 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.
[0111]
1) First, device electrodes 1102 and 1103 are formed on a substrate 1101 as shown in FIG.
[0112]
In the formation, the substrate 1101 is sufficiently washed with a detergent, pure water, and an organic solvent in advance, and then a device electrode material is deposited (as a deposition method, for example, a vacuum film formation method such as an evaporation method or a sputtering method). Technology can be used.) Thereafter, the deposited electrode material is patterned using a photolithography / etching technique to form a pair of element electrodes (1102 and 1103) shown in FIG.
[0113]
2) Next, a conductive thin film 1104 is formed as shown in FIG.
[0114]
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, in this embodiment, Pd is used as the main element. In the example, the dipping method is used as the coating method, but other methods such as a spinner method and a spray method may be used.
[0115]
In addition, as a method for forming a conductive thin film made of a fine particle film, for example, a vacuum vapor deposition 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.
[0116]
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.
[0117]
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.
[0118]
In order to describe the energization method in more detail, FIG. 12 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.
[0119]
In the embodiment, for example, 10 ^-5 In a vacuum atmosphere of about Torr, for example, the pulse width T1 was set to 1 [millisecond], the pulse interval T2 was set to 10 [millisecond], and the peak value Vpf was increased by 0.1 [V] for each pulse. 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 ^-7 When the temperature became A or less, the energization related to the forming process was terminated.
[0120]
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.
[0121]
4) Next, as shown in FIG. 11 (d), an appropriate voltage is applied between the activation power supply 1112 between the device electrodes 1102 and 1103, and an energization activation process is performed to improve the electron emission characteristics. Do.
[0122]
The energization activation process is a process of energizing the electron emission portion 1105 formed by the energization forming process under appropriate conditions to deposit carbon or a carbon compound in the vicinity thereof (in the figure, carbon Or the deposit which consists of a carbon compound was typically shown as the member 1113.) By performing the energization activation process, it is possible to increase the emission current at the same applied voltage typically 100 times or more compared to before the energization activation process.
[0123]
Specifically, 10 ^-4 10 ^-5 By periodically applying a voltage pulse in a vacuum atmosphere within the range of Torr, carbon or a carbon compound originating from an organic compound present in the vacuum atmosphere is deposited. 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.
[0124]
In order to explain the energization method in more detail, FIG. 13A 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. .
[0125]
1114 shown in FIG. 11 (d) is 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 (note that the substrate is a substrate). When the activation process is performed after 1101 is incorporated in the display panel, the phosphor screen of the display panel is used as the anode electrode 1114). While a voltage is applied from the activation power supply 1112, the emission current Ie is measured by the ammeter 1116 to monitor the progress of the energization activation process, and the operation of the activation power supply 1112 is controlled. An example of the emission current Ie measured by the ammeter 1116 is shown in FIG. 13B. When a pulse voltage starts to be applied from the activation power supply 1112, the emission current Ie increases with time, but eventually becomes saturated. And almost no increase. 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.
[0126]
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. .
[0127]
As described above, the planar surface conduction electron-emitting device shown in FIG.
[0128]
(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.
[0129]
FIG. 14 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.
[0130]
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. Therefore, the element electrode interval L in the planar type in FIG. 10 is set as the step height Ls of the step forming member 1206 in the vertical type. Note that for the substrate 1201, the device electrodes 1202 and 1203, and the conductive thin film 1204 using the fine particle film, the materials listed in the description of the planar type can be used similarly. The step forming member 1206 is made of an electrically insulating material such as SiO2.
[0131]
Next, a method for manufacturing a vertical surface conduction electron-emitting device will be described. 15A to 15F are cross-sectional views for explaining the manufacturing process, and the notation of each member is the same as in FIG.
[0132]
1) First, as shown in FIG. 15A, an element electrode 1203 is formed on a substrate 1201.
[0133]
2) Next, as shown in FIG. 2B, an insulating layer for forming a step forming member is laminated. The insulating layer may be formed by, for example, laminating SiO2 by a sputtering method, but other film forming methods such as a vacuum deposition method and a printing method may be used.
[0134]
3) Next, as shown in FIG. 3C, the device electrode 1202 is formed on the insulating layer.
[0135]
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.
[0136]
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, a film forming technique such as a coating method may be used.
[0137]
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. 11C may be performed). .)
[0138]
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 planar energization activation process described with reference to FIG. 11D). The same processing may be performed.)
[0139]
As described above, the vertical surface conduction electron-emitting device shown in FIG. 15F was manufactured.
[0140]
(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.
[0141]
FIG. 16 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.
[0142]
The element used in the display device has the following three characteristics with respect to the emission current Ie.
[0143]
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 is almost not increased. Not detected.
[0144]
That is, the emission current Ie is a non-linear element having a clear threshold voltage Vth.
[0145]
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.
[0146]
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.
[0147]
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, if the first characteristic is used, it is possible to perform display by sequentially scanning the display screen. 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.
[0148]
Further, by using the second characteristic or the third characteristic, the light emission luminance can be controlled, so that gradation display can be performed.
[0149]
(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.
[0150]
FIG. 6 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 similar to those shown in FIG. 10 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.
[0151]
FIG. 7 is a cross-sectional view taken along the line BB ′ of FIG.
[0152]
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, the device was manufactured by supplying power to each element through the row direction wiring 1013 and the column direction wiring 1014 and performing energization forming processing and energization activation processing.
[0153]
(Drive circuit and drive method)
FIG. 17 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.
[0154]
Hereinafter, functions of each part of the apparatus of FIG. 17 will be described in detail.
[0155]
First, the display panel 1701 is connected to an external electric circuit through 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.
[0156]
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 emission element illustrated in FIG. 108 is equal to or lower than the electron emission threshold voltage Vth voltage. It is set to do.
[0157]
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, control signals Tscan, Tsft, and Tmry 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.
[0158]
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.
[0159]
The line memory 1705 is a storage device for storing data for one image line for a necessary time, and appropriately stores the contents of Id1 to Idn according to the 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.
[0160]
The modulation signal generator 1707 is a signal source for appropriately driving and modulating each of the electron-emitting devices 1015 according to each of the image data I′d1 to I′dn, and the output signals thereof are terminals Dy1 to Dyn. And applied to the electron-emitting device 1015 in the display panel 1701.
[0161]
As described with reference to FIG. 16, 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 for electron emission (8 [V] in the case of a surface conduction electron-emitting device of an embodiment described later), and electron emission occurs only when a voltage equal to or higher than the threshold Vth is applied. For a voltage equal to or higher than the electron emission threshold Vth, the emission current Ie also changes according to the voltage change as shown in the graph of FIG. Therefore, when a pulse voltage is applied to the device, for example, no electron emission occurs even when a voltage equal to or lower than the electron emission threshold Vth is applied. However, when a voltage equal to or higher than the electron emission threshold Vth is applied, the surface 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.
[0162]
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.
[0163]
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.
[0164]
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 system, the 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.
[0165]
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 (VCO) can be adopted, and an amplifier for amplifying the voltage up to the driving voltage of the electron-emitting device can be added if necessary.
[0166]
In the image forming apparatus to which the present invention can be applied, it is possible to emit electrons by applying a voltage to each electron-emitting device via the container external terminals Dx1 to Dxm and Dy1 to Dyn. 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.
[0167]
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 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, SECAM system, etc., a TV signal composed of a larger number of scanning lines (high-definition TV including the MUSE system) system. Can also be adopted.
[0168]
As described above, the embodiments of the present invention have been described. However, the present invention is not limited to this, and the electron source has a plurality of cold cathode element rows in which a plurality of cold cathode elements arranged in parallel are connected at both ends ( A ladder that controls electrons from the cold cathode device by a control electrode (also called a grid) arranged above the cold cathode device along a direction (called a column direction) orthogonal to the wiring. It may be an electron source for the arrangement.
[0169]
In addition, according to the idea of the present invention, the image forming apparatus is not limited to an image forming apparatus suitable for display. An image forming apparatus can also be used. At this time, by appropriately selecting the above-mentioned m row-directional wirings and n column-directional wirings, the present invention can be applied not only to a linear light-emitting source but also to a two-dimensional light-emitting source. In this case, the image forming member is not limited to a material that directly emits light, such as a phosphor used in the following examples, and a member that forms a latent image by charging with electrons can also be used.
[0170]
【The invention's effect】
According to the present invention described above, in the image forming apparatus using the spacer having the high resistance film on the surface and having the low resistance film at the connection portion between the multi electron beam source and the face plate, the high resistance film and the low resistance film are provided. Since the spacer that suppresses unexpected electric field concentration at the boundary portion of the resistance film and prevents the occurrence of discharge is used, a highly reliable image forming apparatus can be provided.
[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 cross-sectional view taken along line AA ′ of the display panel of FIG.
FIG. 3 is a schematic view of a spacer viewed from the direction of a flat plate surface.
FIG. 4 is a diagram showing a case where a convex portion is generated on the low resistance film boundary line in the manufacturing process.
FIG. 5 is a diagram showing the degree of electric field concentration when a convex shape occurs
6 is a plan view of a multi-electron beam source used in the display panel of FIG.
7 is a cross-sectional view of the multi-electron beam source of FIG. 6 along BB ′.
FIG. 8 is a layout diagram of a phosphor.
FIG. 9 is another layout diagram of the phosphor.
FIG. 10 is a plan view and a cross-sectional view of a planar surface conduction electron-emitting device.
FIG. 11 is a manufacturing process diagram of a planar surface conduction electron-emitting device.
FIG. 12 is a waveform diagram of the forming voltage.
FIG. 13 is a waveform diagram for explaining activation processing;
FIG. 14 is a sectional view of a vertical surface conduction electron-emitting device.
FIG. 15 is a manufacturing process diagram of a vertical surface conduction electron-emitting device;
FIG. 16 is a graph showing the characteristics of an electron-emitting device
FIG. 17 is a block diagram of a driving circuit for performing television display.
FIG. 18 is a plan view of a conventional surface conduction electron-emitting device.
FIG. 19 is a cross-sectional view of a field emission type electron-emitting device.
FIG. 20 is a cross-sectional view of an MIM type electron-emitting device.
FIG. 21 is a perspective view showing an example of a display panel unit constituting a flat type image forming apparatus.
[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 emission part
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 (7)

An electron source having a cold cathode element, an electrode for controlling electrons emitted from the electron source, an image forming member for forming an image by collision of electrons emitted from the electron source, and the electron source and the electrode In an image forming apparatus having a spacer disposed therebetween,
The spacer has a high resistance film on the surface, and has a low resistance film at a contact portion of the spacer with the electron source and the electrode, and the high resistance film passes through the low resistance film and the electron source and the electrode. Electrically connected to the electrode,
Characterized between the said high-resistance film and the low-resistance film of the spacer, said to the high resistance film of a low-resistance film, that resistance to the high resistance from a low resistance has a continuously changing boundary region An image forming apparatus. The low resistance film, the image forming apparatus according to claim 1, characterized in that it does not have a protrusion beyond the boundary region is reached to the high-resistance film side. The low resistance film, the image forming apparatus according to claim 2, wherein the no protrusion of the height to the high resistance film side more than twice the width thereof. The width of the boundary region, the image forming apparatus according to claim 1, wherein a is 100μm or less 10μm or more. The image forming apparatus according to claim 1, wherein a plurality of the cold cathode elements are connected by wiring, and electrical connection of the spacer to the electron source is made by the wiring. 6. The image forming apparatus according to claim 5 , wherein the wiring to which the plurality of cold cathode elements are connected is a matrix wiring including a plurality of row direction wirings and a plurality of column direction wirings. The image forming apparatus according to claim 1, wherein the high resistance film has a surface resistance value of 10 ⁵ Ω / □ or more and 10 ¹² Ω / □ or less.

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