JP2000082424A - Image forming device and spacer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device forming images, having high luminance and no distortion without making the user aware of the presence of a spacer, when electrons emitted from electron emitting elements are irradiated on a phosphor to emit light with high voltage. SOLUTION: In this image forming device a substrate 13 provided with plural electron emitting elements in a structure where is made to face a transparent substrate provided with a light emitting material through a spacer 22. In the spacer 22, the surface of a base material is coated with a semiconductive film as a first layer, and an insulating film containing Cr2O3 as a second layer is coated on it, and furthermore the insulating film as the second layer has a thickness of less 6.9 nm. The semiconductive film as the first layer has a resistivity of 10-7×Va2 to 105 Ωm, when the thickness is 10 nm-1 μm, and Va is the accelerating voltage for the electrons and has a positive resistance temperature coefficient or absolute value of which is less than 1% of the negative resistance temperature coefficient.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly to a flat type image forming apparatus having a spacer between a substrate on which a plurality of electron-emitting devices are arranged and a transparent substrate on which a luminescent material is formed. It is something that can be done.

[0002]

2. Description of the Related Art Conventionally, two types of electron emitting devices, a hot cathode device and a cold cathode device, are known. Among these, among the cold cathode devices, for example, a surface conduction type emission device, a field emission type device (hereinafter referred to as FE type), a metal / insulating layer / metal type emission device (hereinafter referred to as MIM type), and the like are known. I have.

The surface conduction electron-emitting device utilizes a phenomenon in which an electron is emitted by passing a current through a small-area thin film formed on a substrate in parallel with the film surface. As this surface conduction type emission element, Sn by Elinson et al.
O ₂ those using a thin film [MIElinson, Radio Eng.Electro
n Phys., 10,1290, (1965)], Au thin film [GD Mit
ter: “Thin Solid Films”, 9,317 (1972)] and In ₂ O ₃
/ SnO ₂ thin film [M.Hartwell And CGFonsta
d: “IEEE Trans. ED Conf.”, 519 (1975)] and those using carbon thin films [Hisashi Araki et al .: Vacuum, Vol. 26, No. 1,
22 (1983)].

[0004] As a typical example of the device configuration of these surface conduction electron-emitting devices, FIG. 13 is a plan view of the device by M. Hartwell et al. Described above. In FIG. 1, reference numeral 1 denotes a substrate, and 2 denotes a conductive thin film made of a metal oxide formed by sputtering. The conductive thin film 2 is formed in an H-shaped planar shape as shown. The electron emitting portion 3 is formed by subjecting the conductive thin film 2 to an energization process called energization forming.

In the energization forming, a constant DC voltage or a DC voltage which increases at a very slow rate of, for example, about 1 V / min is applied to both ends of the conductive thin film 2 to energize the conductive thin film 2. Is locally destroyed, deformed, or altered to form the electron-emitting portion 3 having a high electrical resistance. Note that a crack is generated in a part of the conductive thin film 2 that has been locally broken, deformed, or altered. When an appropriate voltage is applied to the conductive thin film 2 after the energization forming, electron emission is performed in the electron emission portion 3 near the crack.

An example of the FE type is, for example, WPDyke
& W.W.Dolan, “Field Emission”, Advance in Electron P
hysics, 8, 89 (1956) or CASpindt, “Physic
al Properties of Thin-Film Field Emission cathodes
with molybdenium Cones ", J. Appl. Phys., 47, 5248 (197
6) are known.

[0007] As a typical example of the FE type device configuration, FIG. 14 is a cross-sectional view of the device by CASpindt et al. Described above.
In the figure, 4 is a substrate, 5 is an emitter wiring made of a conductive material, 6 is an emitter cone of molybdenum or the like, 7 is an insulating layer, and 8 is a gate electrode. In the present electron-emitting device, by applying an appropriate voltage between the emitter cone 6 and the gate electrode 8, field emission is caused from the tip of the emitter cone 6, and electrons are emitted toward the high-voltage electrode provided above. Is done.

As another element structure of the FE type, FIG.
In addition to the conical laminating structure shown in FIG. 4, there is also an example in which an emitter and a gate electrode are arranged on a substrate almost in parallel with the substrate plane.

As an example of the MIM type, for example, CAMe
ad, “Operation of Tunnel-Emission Devices, J. Appl.P
hys., 32, 646 (1961) and the like are known. FIG. 15 shows a typical example of the MIM element configuration. The figure is a cross-sectional view, in which 9 is a substrate, 10 is a lower electrode made of metal, 11 is a thin insulating layer having a thickness of about 100 Å, and 12 is a metal layer having a thickness of about 80 to 300 Å. Electrodes. In the MIM type, electrons are emitted from the surface of the upper electrode 12 by applying an appropriate voltage between the upper electrode 12 and the lower electrode 10.

[0010] The above-described various cold cathode devices can obtain electrons at a lower temperature than the hot cathode device, and thus do not require a heater for heating. Therefore, the structure is simpler than that of the hot cathode element, and a fine element can be produced.
Further, even when a large number of elements are arranged on a substrate at a high density, problems such as thermal melting of the substrate hardly occur. In addition, unlike the hot cathode device, which operates by heating the heater, the response speed is slow, and the cold cathode device also has the advantage that the response speed is fast.

With respect to the application of the cold cathode device, there are an image forming apparatus such as an image display device and an image recording device, and a charged beam source.

In particular, as examples in which a cold cathode element is applied to an image display device, US Pat. No. 5,066,833, JP-A-2-257551 and JP-A-4-28137 by the present applicant.
As disclosed in Japanese Patent Application Laid-Open Publication No. H10-115, an image display device using a combination of a surface conduction electron-emitting device and a phosphor that emits light by irradiation with an electron beam has been studied. There is an image display device that emits light by using a combination of a surface conduction electron-emitting device and a phosphor that emits light when irradiated with an electron beam.

A flat panel display device reported by R. Meyer et al. Is known as an example in which many FE types are applied to an image display device [R. Meyer: “Recent Develo”.
pment on Microchips Display at LETI ", Tech.Digest o
f 4th Int.Vacuum Micro Electronics Conf., Nagahama,
pp.6-9 (1991)].

An example in which a number of MIM types are applied to an image display device is disclosed in Japanese Patent Application Laid-Open No. 3-557 by the present applicant.
No. 38 discloses this.

Among them, the surface conduction electron-emitting device has an advantage that a large number of devices can be easily formed in a large area because the structure is simple and the production is easy.

An image display device using a combination of a surface conduction electron-emitting device and a fluorescent material is self-luminous and does not require a backlight and has a wide viewing angle as compared with a liquid crystal display device. Is better.

In the flat-panel image display device, a large number of the above-described electron-emitting devices are arranged on a flat substrate, and a phosphor which emits light by electrons is arranged in opposition to this. The electron-emitting devices are arranged in a two-dimensional matrix on a substrate (referred to as a multi-electron source).
Each element is connected to a row wiring and a column wiring. As an example of the image display method, there is the following simple matrix drive.

In order to emit electrons from an arbitrary row in the matrix, a selection voltage is applied in the row direction, and a signal voltage is applied to the column wiring in synchronization with the selection voltage.

The electrons emitted from the electron-emitting devices in the selected row are accelerated toward the phosphor to excite and emit the phosphor. An image is displayed by sequentially applying a selection voltage in the row direction.

It is necessary to maintain a vacuum between a substrate (rear plate) on which electron-emitting devices are formed in a two-dimensional matrix and a substrate (face plate) on which phosphors and acceleration electrodes are formed. Since atmospheric pressure is applied to the rear plate and the face plate, a substrate having a thickness to support the atmospheric pressure is required as the display device becomes larger. However, this causes an increase in weight, so a structure that keeps the distance between the rear plate and the face plate constant by inserting a support member (spacer) between the rear plate and the face plate and also prevents damage to the rear plate and the face plate is required. Taken.

The spacer is required to have sufficient mechanical strength to support the atmospheric pressure, and must not significantly affect the trajectory of electrons flying between the rear plate and the face plate. The cause that affects the electron orbit is the charging of the spacer. Spacer charging is when part of the electrons emitted from the electron source or secondary electrons reflected on the face plate are incident on the spacer, and secondary electrons are emitted from the spacer. It is considered to be due to adhesion to the surface.

When the spacer is positively charged, electrons flying near the spacer are attracted to the spacer, so that a display image is distorted near the spacer. The effect of charging becomes more pronounced as the distance between the rear plate and the face plate increases.

In general, as a means for suppressing charge, a charge is imparted to a charged surface and a small amount of current is applied to remove the charge. A method of applying this concept to a spacer and coating the surface of the spacer with tin oxide is disclosed in
18355. In addition, Japanese Unexamined Patent Publication
No. 49135 discloses a method of coating with a PdO-based glass material.

Also, high luminance is an important factor for an image display device. In order to efficiently emit light from the phosphor formed on the face plate, it is sufficient to irradiate the phosphor with electrons accelerated at a high voltage. To emit light with sufficient efficiency, the height of the spacer is 1 to 8 mm. As a degree, the accelerating electrode voltage may be accelerated to 3 kV or more, preferably 5 kV or more. Therefore, a voltage of several kV or more is applied between the rear plate and the face plate, and a voltage having substantially the same potential is applied to both ends of the spacer. It is required that the material used for the spacer does not discharge when an acceleration voltage is applied.

As a means for improving the surface discharge breakdown voltage, it is effective to cover the surface with a material having a low secondary electron emission rate.
Chromium oxide (TSSudarshan and JDCross: IEEE Tran.EI-1)
1, 32 (1976)), copper oxide (JDCross and TSsudarshan: IE
EE Tran.EI-9146 (1974)) is known.

[0026]

However, when the above oxide semiconductive material such as tin oxide or copper oxide is applied to a spacer of an image display device having a multi-electron source,
In the following points, sufficient performance may not be exhibited. That is, since the oxide semiconductive material has a low specific resistance, the current flowing on the surface of the spacer becomes too large unless it is coated very thinly. If the resistance is low, in an image display device using a high acceleration voltage, heat generation of the spacer portion becomes a problem. In addition, since the resistance value of the oxide semiconductive material changes greatly depending on the atmospheric gas, it is difficult to control the resistance with a very thin thin film, and therefore, it is not possible to reproducibly manufacture a spacer.

That is, although it has been predicted that physical properties that are preferable as the material of the spacer or its surface layer have been predicted, electrons emitted from the multi-electron source are accelerated by a voltage of 3 kV or more, thereby causing the phosphor to emit light. No material suitable as a spacer for an image forming apparatus represented by the formula (1). Therefore, it has been difficult to realize an image forming apparatus that forms an image with high luminance and no distortion by causing the phosphor to emit light at a high voltage.

Accordingly, the present invention overcomes the above various difficulties, and does not make the presence of the spacers sense when irradiating the electrons emitted from the electron-emitting device to cause the phosphor to emit light at a high voltage. Another object of the present invention is to provide an image forming apparatus that forms an image with high luminance and no distortion.

[0029]

An image forming apparatus according to the present invention is directed to an image forming apparatus having a structure in which a substrate on which a plurality of electron-emitting devices are formed and a transparent substrate on which a light emitting material is formed are opposed to each other via a spacer. The spacer has a thickness of 10 nm to 1 μm as a first layer on the surface of the base material, and has a specific resistance of 10 ⁻⁷ × Va ² to 10 ⁵ Ω when the acceleration voltage of electrons is Va.
m, a film having a positive temperature coefficient of resistance or a negative temperature coefficient of resistance having an absolute value of 1% or less;
A Cr ₂ O ₃ layer having a thickness of 6.9 nm or less is formed thereon as a second layer.
An image forming apparatus is a spacer covered with an insulating film containing at least:

A voltage is applied to both ends of the first layer so as to generate a potential difference between both ends of the spacer, and a voltage is applied to the substrate on which the plurality of electron-emitting devices are formed. An accelerating electrode for accelerating the generated electrons is provided, and one end of the spacer is electrically connected to the accelerating electrode. Further, the electron-emitting device is a surface conduction electron-emitting device.

The spacer according to the present invention is coated with a semiconductive film as a first layer on the surface of a flat, cross-shaped, L-shaped, or column-shaped base material. It is characterized by being covered with an insulating film containing Cr ₂ O ₃ as two layers, and the thickness of the insulating film of the second layer is not less than 0.8 nm and not more than 6.9 nm. The insulating film has a resistance value of not less than 10 ⁴ Ωm in volume resistance and is used for a display panel.

[0032]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments according to the present invention will be described.
This will be described in detail with reference to the drawings.

[Display Panel] FIG. 3 is a perspective view of a display panel as an application example of the image display device according to the present invention, and a part of the panel is cut away to show the internal structure. In FIG. 3, reference numeral 13 denotes a substrate on which an electron-emitting portion is mounted, 14 denotes an electron-emitting device having an electron-emitting portion, 15 denotes a wiring in an x-axis row direction applied to the electron-emitting device 14, and 16 denotes a wire applied to the electron-emitting device 14. Reference numeral 17 denotes a rear plate, reference numeral 18 denotes a side plate, and reference numeral 19 denotes a face plate. Reference numerals 17 to 19 form an airtight container for maintaining the inside of the display panel at a vacuum.

When assembling the airtight container, it is necessary to seal the joints of the members in order to maintain sufficient strength and airtightness. For example, frit glass is applied to the joints, and the joints are exposed to air or a nitrogen atmosphere. And 400 to 5 degrees Celsius
Sealing was achieved by firing at 00 ° C. for 10 minutes or more. A method of evacuating the inside of the airtight container to a vacuum will be described later. Further, since the inside of the hermetic container is maintained at a vacuum of about 10 ^-4 Pa, it is used as an anti-atmospheric structure for the purpose of preventing destruction of the hermetic container due to atmospheric pressure or unexpected impact.
A spacer 22 is provided. Reference numeral 20 denotes a phosphor of a light emitting material provided in the face plate 19, and reference numeral 21 denotes a metal back which functions as a high-voltage electrode to attract an electron flow.

[Structure and Manufacturing Method of Display Panel] Next, the structure and manufacturing method of the display panel of the image display device to which the present invention is applied will be described with reference to specific examples. FIG. 1 is a schematic cross-sectional view of the display device centering on the spacer 22. Each number corresponds to FIG. The same parts as those in FIG. 3 are denoted by the same reference numerals, and redundant description will be omitted. In the figure, 13 is a substrate, 14 is a cold cathode electron source, 17 is a rear plate, 18 is a side wall, 19 is a face plate, and an envelope is formed by reference numerals 17 to 19, and the inside of the display panel is evacuated. It forms an airtight container for maintenance.

In the rear plate 17, the wiring 15 in the row direction is formed on the insulating layer 57, and the face plate 19 is formed of a phosphor 20 from the transparent glass substrate, a metal back 21 serving as a high-voltage electrode, and the like. It is composed of Alternatively, the transparent electrode 20 such as ITO and the phosphor 19 may be laminated from the transparent glass substrate. In the present embodiment, a description will be given as the phosphor 20. The spacer 22 includes an insulating base material 24, a first layer 23 a covering the insulating base material 24, and a second layer 23 b above the insulating substrate 24. The lower part is covered, and is adhered and fixed on the wiring 15 in the row direction with a conductive adhesive 26. On the face plate 19 side, the upper part of the spacer 22 is covered with a low-resistance film 25, and is adhered and fixed below the metal back 21 with a conductive adhesive 26.

The spacer 22 is formed on the surface of an insulating base material 24 such as ceramic or glass.
An insulating film 23b of 9 nm or less is formed. The spacer 22 is provided to receive atmospheric pressure by evacuating the inside of the envelope, to withstand atmospheric pressure, and to prevent the envelope from being damaged or deformed. The material of the spacer 22,
The shape, arrangement, and number of arrangements are determined in consideration of the shape of the envelope, the coefficient of thermal expansion, the atmospheric pressure, heat, and the like that the envelope receives. Examples of the shape of the spacer include a flat plate type, a cross shape, an L shape, a columnar shape, and a flat plate type having a hole in an electron beam passage portion.

The insulating substrate 24 is preferably made of a material having substantially the same thermal expansion characteristics as the rear plate 17 on which the electron-emitting devices are formed and the face plate 19 on which the phosphor is formed. Alternatively, the insulating base material 24 may have high elasticity and easily absorb thermal deformation. Since it is necessary to support the atmospheric pressure applied to the face plate 19 and the rear plate 17, mechanical strength such as glass and ceramics is high,
Materials with high heat resistance are suitable. When glass is used as the material of the face plate 19 and the rear plate 17, the spacer 22 is used to reduce the thermal stress during the process of manufacturing the display device.
It is desirable that the insulating base material 24 be the same as these materials as much as possible or a material having a similar thermal expansion coefficient.

[Spacer in Display Panel] As a result of studying a method for preventing the spacer 22 from being charged, the present inventors have found that a thin oxide film is formed on the first conductive film to remove the charged charge. Has been found to be effective. In particular, the secondary electron emission efficiency of Cr ₂ O ₃ etc. is small,
A configuration in which an insulating film is coated with a thickness of 69 angstroms or less is extremely effective. FIG. 2 is a schematic view showing the structure of a spacer, in which a first layer 23a having semiconductivity and a second layer 23b which is an oxide insulating layer are formed on an insulating substrate 24.
Are formed.

The semiconductive first layer 23a removes the electric charges charged on the surface of the spacer 22, so that the spacer 22 is not largely charged. The second layer 23b is made of a material having a low secondary electron emission efficiency to suppress the charge.

The resistance value of the first layer 23a is set to a value at which a sufficient current flows through the spacer 22 to quickly remove charges without charging the surface of the spacer 22. Therefore, the resistance value suitable for the spacer 22 is set by the charge amount. The amount of charge depends on the emission current from the electron source and the secondary electron emission rate on the surface of the spacer 22.
_{Since 2} O ₃ is a material having a low secondary electron emission rate, it is not necessary to flow a large current. It is considered that if the sheet resistance of the first layer 23a is 10 ¹² Ω / □ or less, it is possible to cope with most use conditions, but if the sheet resistance is 10 ¹¹ Ω / □ or less, it is satisfactory. On the other hand, the lower limit of the resistance value is limited by the power consumption in the spacer 22, and the power consumption of the entire image display apparatus does not increase excessively. Therefore, the resistance of the spacer 22 must be selected so as not to greatly affect the heat generation of the entire apparatus. .

The first layer 23a used for the spacer 22 is preferably a semiconductive material rather than a metal film having a small specific resistance. The reason is that when a material having a low specific resistance is used, the thickness of the antistatic film must be extremely thin in order to set the sheet resistance Rs to a desired value. Although it differs depending on the surface energy of the thin film material, the adhesion to the substrate, and the substrate temperature, generally, a thin film smaller than 10 nm has an island shape, has an unstable resistance, and has poor film reproducibility. Therefore, the specific resistance value is larger than the metal conductor,
Semi-conductive materials in a smaller range than insulators are preferred.

When the temperature coefficient of resistance of the spacer 22 is positive, the resistance value increases as the temperature increases, so that heat generation in the spacer 22 is suppressed. Conversely, if the temperature coefficient of resistance is negative, the resistance value decreases due to the temperature rise due to the power consumed on the spacer surface, and further heat is generated, the temperature continues to rise, causing an excessive current to flow, so-called thermal runaway. However, in a situation where the calorific value, that is, the power consumption and the heat radiation are balanced, the thermal runaway does not occur. Therefore, if the absolute value of the temperature coefficient of resistance (TCR) is small, it is difficult to cause thermal runaway.

The temperature coefficient of resistance (TCR) of the spacer 22 is
Under conditions using a thin film of about -1%, 1 cm
^TwoPower consumption per unit exceeds 0.1 W
As a result, the current flowing through the spacer 22 continues to increase, causing a thermal runaway condition.
It was confirmed in the experiment that it was in a state. This is of course
Voltage applied between the spacer shape and the spacer,
It depends on the temperature coefficient of resistance of the barrier film.
Power consumption is 1cm ^TwoSea not to exceed 0.1W per
The value of the resistance Rs is 10 × Va^TwoΩ or more. That is,
The sheet resistance Rs of the first layer formed on the spacer 22 is 1
0 × Va^Two-10 ¹¹Should be set to the range of Ω.
No.

The thickness t of the first layer 23a is 10 as described above.
nm or more is desirable. On the other hand, when the film thickness t exceeds 1 μm, the film stress increases, and the risk of film peeling increases.
Productivity is poor because the deposition time is long. Therefore, the film thickness is 10 nm to 1 μm, more preferably 20 nm to 500 μm.
nm is desirable.

The specific resistance ρ is the product of the sheet resistance Rs and the film thickness t.
Yes, the sheet resistance Rs and the film thickness t described above are preferable.
From the range, the specific resistance ρ of the antistatic film is 10^-7× Va^TwoΩm ~
10 ^FiveΩm is desirable. Further sheet resistance and film
To achieve a more preferred range of thickness, ρ is (2 ×
10^-7) × Va^TwoΩm ~ 5 × 10^FourΩm is preferable.
Acceleration voltage V of electrons on the display of the image display device
a is 100V or more, which is a high-speed
Sufficient when using electronic phosphors for flat displays
A voltage of 3 kV or more is required to obtain a high luminance. Va
= 1 kV, the specific resistance of the antistatic film is 0.1.
1Ωm-10^FiveΩm is a preferable range.

As a material of the first layer 23a, any material can be used as long as its resistance can be adjusted to a preferable range for the above-described spacer and the material is stable, and an oxide, a nitride, or the like can be used. Among them, a complex of a transition metal and the ceramic, (cermet), Cr-SiO, Cr- SiO 2, Cr-Al 2
O ₃ , In ₂ O ₃ —Al ₂ O _3, or a composite of a transition metal and a high-resistance nitride (such as aluminum nitride, boron nitride, or silicon nitride); Cr—Al—N; Ti—Al—N; Al-
N, Cr-BN, Cr-Si-N, etc. are preferable materials whose resistance value is easily adjusted and whose resistance value is stable during the image forming apparatus manufacturing process.

Further, by providing the second layer 23b of the oxide on the surface of the first layer 23a, the surface oxidation of the first layer 23a is suppressed in the image forming apparatus manufacturing process, and higher resistance value stability can be obtained. Further, the image forming apparatus manufacturing process conditions to be applied simultaneously can be selected from a wider range.

The resistance value of the entire spacer 22 is substantially equal to that of the first layer 2.
3a. In order to prevent disturbance in the trajectory of the electrons emitted from the electron source, the face plate 1
It is necessary that the potential distribution between the rear plate 9 and the rear plate 17 is uniform, that is, the resistance value of the spacer 22 is substantially uniform at all places. When the potential distribution is disturbed, the electrons that should reach the phosphor near the spacer 22 are bent, and the electrons hit the adjacent phosphor, thereby disturbing the image. Cr,
The nitride films of Ti and Ta are stable, and are effective in ensuring uniformity of the resistance value and preventing image disturbance.

The material used for the second layer 23b is preferably a material having a low secondary electron emission rate. Cr ₂ O ₃ has a low secondary electron emission efficiency and is a material suitable for use in the second layer 23b. According to our measurements, the secondary electron emission efficiency of these materials is at most 1. at an incident angle of 0 °.
Do not exceed 8 °.

However, these materials have a volume resistance of 10 ^8.
It is an insulator having a resistance value of Ωcm or more, and it is difficult to release electric charges, and thus cannot be used alone. However, by using it as the second layer of the two-layer structure of the present invention, the characteristics can be maximized.

Although Cr ₂ O ₃ used for the second layer 23b has a small secondary electron emission coefficient, the charge accumulated when charged is combined with the opposite-polarity charge in the first layer so that the charge is moderate. Be summed up. The charge in the second layer moves due to the potential gradient caused by diffusion or charging, but the mobility of these materials, which are insulators, is much slower than that of a good conductor, so if the film thickness is too thick, the charge can be quickly removed. It becomes difficult. If the second layer 23b is thin, charge transfer by the tunnel effect can be expected, so the thickness of the second layer needs to be 10 nm or less.

Although it differs depending on the material and the film forming method, in many cases, experimental results have been obtained in which the effect of preventing static charge is reduced when the film thickness is set to 0.8 nm or less. On the other hand, as described above, it is preferable that the film thickness be as small as possible in order to release the charges accumulated in the second layer 23b to the first layer. Therefore, in consideration of the above, the thickness of the second layer 23b containing Cr ₂ O ₃ is more preferably in the range of 0.8 nm to 6.9 nm, though it depends on the material.

The first layer 23a can be formed on an insulating substrate by a thin film forming means such as a sputtering method, a reactive sputtering method, an electron beam evaporation method, an ion plating method, an ion assist evaporation method, and a CVD method. . Also, the second layer 2
3b can be formed by a reactive sputtering method, an ion assisted vapor deposition method, a CVD method, an ion beam sputtering method, or the like. For example, in the case of reactive sputtering, the formation can be performed by sputtering a graphite target in a nitrogen atmosphere or a mixed atmosphere of argon and nitrogen.

[Configuration and Manufacturing Method of Display Panel of Image Display Device] Next, the configuration and manufacturing method of the display panel of the image display device to which the present invention is applied will be described with reference to specific examples.

FIG. 3 is a perspective view of the display panel used in this embodiment as described above, and a part of the panel is cut away to show the internal structure.

A substrate 13 is fixed to the rear plate 17, and N × M cold cathode elements 14 are formed on the substrate. Here, 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 displaying high-definition television, it is desirable to set N = 3000 and M = 1000 or more. The N × M cold cathode elements are arranged in a simple matrix by M row-directional wirings 15 and N column-directional wirings 16. The portion constituted by the substrate 13, the row direction wiring 15, and the column direction wiring 16 is called a multi-electron beam source.

The multi-electron beam source used in the image display apparatus according to the present invention is not limited as long as the cold cathode device is a simple matrix-wired electron source. Therefore, for example, a cold cathode device such as a surface conduction type emission device, an FE type, or an MIM type can be used. Further, the electron source can be formed directly on the rear plate.

Next, the structure of a multi-electron beam source in which surface conduction electron-emitting devices (described later) are arranged on a substrate as a cold cathode device 14 and arranged in a simple matrix will be described.

FIG. 4 is a plan view of the multi-electron beam source used for the display panel of FIG. On the substrate 13, surface conduction electron-emitting devices similar to a multi-electron beam source having an electron-emitting device shown in FIG. 5 described later are arranged, and these devices are simply formed by row-direction wiring electrodes 15 and column-direction wiring electrodes 16. They are wired in a matrix. An insulating layer (not shown) is formed between the row direction wiring electrodes 15 and the column direction wiring electrodes 16 at the intersections of the electrodes to maintain electrical insulation.

FIG. 5 is a sectional view taken along the line BB ′ of FIG.
(B).

The multi-electron beam source having such a structure includes a row-direction wiring electrode 15, a column-direction wiring electrode 16, an interelectrode insulating layer (not shown), and a device electrode of a surface conduction electron-emitting device. After forming the conductive thin film and the conductive thin film, power is supplied to each element through the row-direction wiring electrodes 15 and the column-direction wiring electrodes 16 to perform an energization forming process (described later) and an energization activation process (described below).

In this embodiment, the substrate 13 of the multi-electron beam source is fixed to the rear plate 17 of the airtight container. However, if the substrate 13 of the multi-electron beam source has a sufficient strength, Alternatively, the substrate 13 of the multi-electron beam source may be used as the rear plate 17 of the airtight container.

On the lower surface of the face plate 19,
A fluorescent film 20 is formed. Since the present embodiment is a color display device, the fluorescent film 20 has three primary colors of red, green, and blue used in the field of CRT using an electron beam similar to the electron beam of the cold cathode electron emission device. The body is painted separately. The phosphor of each color is, for example, as shown in FIG.
The black conductor 20a is provided between the stripes of the phosphor as shown in FIG. The purpose of providing the black conductor 20a is to prevent the display color from being shifted even if the electron beam irradiation position is slightly shifted, and to prevent the reflection of external light to prevent the display contrast from lowering. Things. When the black body 20a is made conductive, it is possible to prevent the fluorescent film from being charged up by the electron beam. Although graphite is used as a main component for the black conductor 20a, any other material may be used as long as it is suitable for the above purpose.

The method of applying the phosphors of the three primary colors is not limited to the stripe arrangement shown in FIG. 6A, but may be, for example, a delta arrangement as shown in FIG. Other arrangements may be used.

When a monochrome display panel is manufactured, a monochromatic phosphor material may be used for the phosphor film 20b, and a black conductive material may not necessarily be used.

On the surface of the fluorescent film 20 on the rear plate 17 side, a metal back 21 known in the field of CRT cathode ray tubes is provided. The purpose of providing the metal back 21 is to improve the light utilization rate by mirror-reflecting a part of the light emitted from the fluorescent film 20, to protect the fluorescent film 20 from the collision of negative ions, and to increase the electron beam acceleration voltage. To act as an electrode for applying an electric field, or to act as a conductive path for the excited electrons of the fluorescent film 20. Metal back 2
1 is that after forming the fluorescent film 20 on the face plate substrate 19, the surface of the fluorescent film 20 is smoothed, and
Was formed by a vacuum deposition method. The fluorescent film 20
When a low-voltage phosphor material is used, the metal back 21 is not used.

Although not used in the present embodiment, for the purpose of applying an acceleration voltage and improving the conductivity of the fluorescent film, a transparent material made of, for example, ITO is provided between the face plate substrate 19 and the fluorescent film 20. Electrodes may be provided.

As shown in FIG. 1, a spacer 22 is formed by forming a semiconductive film 23a on the surface of an insulating base material 24, and inside the face plate 19 (such as the metal back 21) and the surface of the substrate 13 (row). The low resistance film 25 is formed on the contact surface and the side surface of the spacer 22 facing the direction wiring 15 or the column direction wiring 16). They are arranged at necessary intervals, and are fixed to the inside of the face plate and the surface of the substrate 13 by the bonding material 26. Also, the semiconductive film 23a
Is formed on at least the surface of the insulating member 24 that is exposed to vacuum in the hermetic container, and is formed via the low-resistance film 25 and the conductive bonding material 26 on the spacer 22. Inside of the face plate 19 (metal back 21
Etc.) and the surface of the substrate 13 (row direction wiring 15 or column direction wiring 16). The shape of the spacer 22 in the embodiment described here is a thin plate, is arranged in parallel with the row direction wiring 15, and is electrically connected to the row direction wiring 15.

The low resistance film 25 constituting the spacer 22 is
Provided for electrically connecting the insulating film 23b or the semiconductive film 23a to the face plate 19 (metal back 21 and the like) on the high potential side and the substrate 17 (wirings 15 and 16 etc.) on the low potential side. In the following, the name of an intermediate electrode layer (intermediate electrode) is also used for the low-resistance film 25.
The intermediate electrode layer (intermediate layer) has a plurality of functions listed below.

(1) The semiconductive film 23a is electrically connected to the face plate 19 and the substrate 13.

As described above, the semiconductive film 23a is provided for the purpose of preventing electrification on the surface of the spacer 22, but the semiconductive film 23a is
9 (metal back 21 etc.) and substrate 13 (wiring 15, 1
6) directly or via the joining material 26,
There is a possibility that a large contact resistance is generated at the interface of the connection portion, and the charge generated on the surface of the spacer 22 cannot be quickly removed. In order to avoid this, a low-resistance intermediate electrode 25 is provided on the contact surface or side surface of the spacer 22 that comes into contact with the face plate 19, the substrate 13, and the contact member 26.

(2) The potential distribution of the semiconductive film 23a is made uniform.

Electrons emitted from the cold cathode element 14 form electron orbits according to the potential distribution formed between the face plate 19 and the substrate 13. In order not to disturb the electron orbit near the spacer 22, the semiconductive film 2
It is necessary to control the potential distribution of 3a over the entire area.
When the semiconductive film 23a is connected to the face plate 19 (such as the metal back 21) and the substrate 13 (such as the wirings 15 and 16) directly or via the contact member 26, the connection is made due to the contact resistance at the interface of the connection portion. The state unevenness occurs, and the semiconductive film 2
3 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 (contact surface or side surface) where the spacer 22 contacts the face plate 19 and the substrate 13, and a desired potential is applied to the intermediate layer. By applying the voltage, the potential of the entire semiconductive film 23 can be controlled.

(3) The trajectory of the emitted electrons is controlled.

Electrons emitted from the cold cathode element 14 form electron orbits in accordance with a potential distribution formed between the face plate 19 and the substrate 13. Regarding the electrons emitted from the cold cathode device 14 near the spacer 22, the spacer 22
Restrictions (wiring, change of element position, etc.)
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 a desired position on the face plate 19 with the electrons. By providing a low-resistance intermediate layer 25 on the side surface of the surface in contact with the face plate 19 and the substrate 13, the potential distribution near the spacer 22 can have desired characteristics and the trajectory of emitted electrons can be controlled. I can do it.

The low-resistance film 25 serving as an intermediate electrode is made of a semiconductive material.
Select a material having a resistance value sufficiently lower than that of the film 23a.
Ni, Cr, Au, Mo, W, Pt, Ti,
Metals or alloys such as Al, Cu, Pd, and Pd,
Ag, Au, RuO_Two, Pd-Ag and other metals and metal oxidation
Printed conductor composed of a product and glass, or In _Two
O_Three-SnO_TwoEtc., transparent conductors and semi-conductors such as polysilicon
It is appropriately selected from body materials and the like.

The bonding material 26 is formed such that the spacer 22 is formed in the row direction wiring 1.
5 and the metal back 21 so as to be electrically connected to each other.
It is necessary to have conductivity. That is, frit glass to which a conductive adhesive, metal particles, or a conductive filler is added is preferable.

Further, Dx1 to Dxm and Dx1 shown in FIG.
y1 to Dyn and Hv are electric connection terminals of an airtight structure provided for electrically connecting the display panel to an electric circuit (not shown). Dx1 to Dxm are electrically connected to the row wiring 15 of the multi-electron beam source, Dy1 to Dyn are electrically connected to the column wiring 16 of the multi-electron beam source, and the acceleration voltage Hv is electrically connected to the metal back 21 of the face plate.

Further, in order to evacuate the inside of the hermetic container, after assembling the hermetic container, an exhaust pipe (not shown) and an exhaust pump are connected, and the inside of the hermetic container is evacuated to a degree of vacuum of about 10 ^-5 Pa. . Thereafter, the exhaust pipe is sealed, but a getter film (not shown) is formed at a predetermined position in the airtight container immediately before or after the sealing in order to maintain the degree of vacuum in the airtight container. The getter film is, for example, a film formed by heating and depositing a getter material containing Ba as a main component by a heater or high-frequency heating, and the inside of the airtight container is 1 × 10 ⁻³ or less due to the adsorption action of the getter film. 1 × 10
The vacuum is maintained at ^-5 Pa.

In the image display apparatus using the display panel described above, when a voltage is applied to each of the cold cathode devices 14 through the external terminals Dx1 to Dxm and Dy1 to Dyn,
Electrons are emitted from each cold cathode device 14. At the same time, a high voltage of several kV is applied to the metal back 21 through the external terminal Hv to accelerate the emitted electrons and collide with the inner surface of the face plate 19. As a result, the phosphors of each color forming the fluorescent film 20 are excited and emit light, and an image is displayed.

Usually, the voltage applied to the surface conduction electron-emitting device 14 of the present invention, which is a cold cathode device, is about 12 to 16 [V].
The distance d between the metal back 21 and the cold cathode device 14 is 1 mm.
And the voltage between the metal back 21 and the cold cathode element 14 is about 3 kV to about 15 kV.

The basic configuration and manufacturing method of the display panel according to the embodiment of the present invention and the outline of the image display device have been described above.

[Configuration and Manufacturing Method of Multi-Electron Beam Source] Next, a manufacturing method of the multi-electron beam source used for the display panel of the above embodiment will be described. The material, shape, and manufacturing method of the cold cathode device are not limited as long as the multi-electron beam source used in the image display device related to the image display device of the present invention is an electron source in which the cold cathode devices 14 are arranged in a simple matrix. Therefore, for example, a cold cathode device such as a surface conduction electron-emitting device, an FE type, or an MIM type can be used.

However, in a situation where a display device having a large display screen and an inexpensive display device is required, a surface conduction electron-emitting device is particularly preferable among these cold cathode devices. That is, in the FE type, since the relative position and shape of the emitter cone and the gate electrode greatly affect the electron emission characteristics, extremely high-precision manufacturing technology is required, but this achieves a large area and a reduction in manufacturing cost. Is a disadvantageous factor. In the case of the MIM type, it is necessary to make the thicknesses of the insulating layer and the upper electrode thin and uniform, which is also a disadvantageous factor in achieving a large area and a reduction in manufacturing cost.
On the other hand, since the surface conduction electron-emitting device has a relatively simple manufacturing method, it is easy to increase the area and reduce the manufacturing cost.

The present inventors have found that among the surface conduction electron-emitting devices, those in which the electron-emitting portion or its peripheral portion is formed of a fine particle film have particularly excellent electron-emitting characteristics and can be easily manufactured. Have found. Therefore, it can be said that it is most suitable for use in a multi-electron beam source of a high-luminance, 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 was used. Therefore, the basic configuration, manufacturing method and characteristics of a suitable surface conduction electron-emitting device will be described first, and then the structure of a multi-electron beam source in which many devices are arranged in a simple matrix will be described.

(Suitable Device Configuration and Manufacturing Method of Surface Conduction Electron Emission Device) Typical configurations of a surface conduction electron emission device in which an electron emission portion or its peripheral portion is formed from a fine particle film include a planar type and a vertical type. There are two types.

(Planar Surface Conduction Electron Emitting Element) First, the element configuration and manufacturing method of a flat surface conduction electron emitting element will be described. FIG. 5 is a plan view for explaining the configuration of a planar surface conduction electron-emitting device (a).
And a sectional view (b). In the figure, 13 is a substrate, 27 and 28 are device electrodes, 29 is a conductive thin film, 30 is an electron emitting portion formed by an energization forming process, and 31 is a thin film formed by an energization activation process.

As the substrate 13, for example, various glass substrates such as quartz glass and blue plate glass, various ceramics substrates such as alumina, or an insulating layer made of, for example, SiO ₂ is formed on the various substrates described above. A laminated substrate or the like can be used.

The device electrode 27 and the device electrode 28 provided on the substrate 13 in parallel with the substrate surface are formed of a conductive material. For example, Ni,
Cr, Au, Mo, W, Pt, Ti, Cu, Pd, Ag
And other metals, or alloys of these metals,
Alternatively, a material may be appropriately selected from metal oxides such as In ₂ O ₃ —SnO ₂ , semiconductors such as polysilicon, and the like. An electrode can be easily formed by using a combination of a film forming technique such as vacuum evaporation and a patterning technique such as photolithography and etching. However, the electrode can be formed by other methods (for example, printing technique). I can't wait.

The shapes of the device electrodes 27 and 28 are appropriately designed according to the application purpose of the electron-emitting device. Generally, the electrode spacing L is usually designed by selecting an appropriate value from the range of several hundreds of angstroms to several hundreds of micrometers. 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.

A fine particle film is used for the conductive thin film 29. The fine particle film described here refers to a film including a large number of fine particles as constituent elements (including an island-shaped aggregate). When the fine particle film is examined microscopically, usually, a structure in which the individual fine particles are spaced 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.

The particle size of the fine particles used in the fine particle film is in the range of several Angstroms to several thousand Angstroms, and preferably in the range of 10 Angstroms to 200 Angstroms. Further, the thickness of the fine particle film is appropriately set in consideration of various conditions described below. That is, the device electrode 27
Or conditions necessary for good electrical connection with 28, conditions necessary for performing energization forming satisfactorily described below, conditions necessary for setting the electrical resistance of the fine particle film itself to an appropriate value described below, And so on. Specifically, it is set in the range of several Angstroms to several thousand Angstroms, but the range is preferably between 10 Angstroms and 500 Angstroms.

Materials that can be used to form the fine particle film include, for example, Pd, Pt, Ru, Ag,
Au, Ti, In, Cu, Cr, Fe, Zn, Sn, T
a, W, Pb, and other metals, PdO, S
Oxides such as nO ₂ , In ₂ O ₃ , PbO, Sb ₂ O ₃ , HfB ₂ , ZrB ₂ , LaB ₆ , Ce
Borides such as B ₆ , YB ₄ , GdB ₄ , etc., TiC, ZrC, HfC, TaC, SiC, WC,
And other carbides, TiN, ZrN, Hf
Nitrides such as N, etc., semiconductors such as Si, Ge, etc., carbon, and the like are listed, and are appropriately selected from these.

As described above, the conductive thin film 29 is formed of a fine particle film. The sheet resistance of the conductive thin film 29 is set to be in the range of 10 ³ to 10 ⁷ [ohm / sq]. did.

Since it is desirable that the conductive thin film 29 and the device electrodes 27 and 28 are electrically connected well, a structure is adopted in which a part of the conductive thin film 29 and each of the device electrodes 27 and 28 overlap each other.
5 and 7, in the example shown in FIG. 5 and FIG. 7, the substrate 13, the device electrodes 27 and 28, and the conductive thin film 29 are stacked in this order. The electrodes may be stacked in this order.

The electron emitting section 30 is formed of a conductive thin film 29.
Is a crack-like portion formed in a part of the conductive thin film 29, and has a higher electrical resistance than the surrounding conductive thin film 29.
The cracks are formed by performing a later-described energization forming process on the conductive thin film 29. In the crack,
In some cases, fine particles having a particle size of several angstroms to several hundred angstroms are arranged. Since it is difficult to accurately and accurately show the actual position and shape of the electron-emitting portion, they are schematically shown in FIG.

The thin film 31 is a thin film made of carbon or a carbon compound, and covers the electron emitting portion 30 and its vicinity. After the energization forming process, the thin film 31
It is formed by performing an energization activation process described later.

The thin film 31 is made of any one of single-crystal graphite, polycrystalline graphite, and amorphous carbon, or a mixture thereof, and has a thickness of 500 [Å] or less, but 300 [Å] or less. Is more preferred.

The basic structure of the preferred device has been described above. In the embodiment, the following device was used.

That is, blue glass was used for the substrate 13 and Ni thin films were used for the device electrodes 27 and 28. The thickness d of the device electrode was 1000 [angstrom], and the electrode interval L was 2 [micrometer].

Pd or P as the main material of the fine particle film
Using dO, the thickness of the fine particle film was about 100 [angstrom], and the width W was 100 [micrometer].

Next, a method of manufacturing a preferred flat surface-conduction type electron-emitting device will be described.

FIGS. 7A to 7D are cross-sectional views for explaining a manufacturing process of the surface conduction electron-emitting device. The notation of each member is the same as that in FIG.

(1) First, as shown in FIG. 7A, device electrodes 27 and 28 are formed on a substrate 13.

Before forming, the substrate 1
After sufficiently cleaning 3 with a detergent, pure water and an organic solvent, the material of the device electrode is deposited. As a deposition method, for example, a vacuum film forming technique such as an evaporation method or a sputtering method may be used. After that, the deposited electrode material is patterned using photolithography and etching technology,
A pair of device electrodes (27 and 28) shown in FIG.

(2) Next, a conductive thin film 29 is formed as shown in FIG.

In forming the conductive thin film 29,
First, an organic metal solution is applied to the substrate (a), dried, heated and baked to form a fine particle film, and then patterned into a predetermined shape by photolithography and etching. Here, the organic metal solution refers to the conductive thin film 29.
This is a solution of an organometallic compound containing, as a main element, a material of fine particles used for the above. Specifically, in this embodiment, Pd is used as a main element. In this embodiment, the dipping method is used as the coating method, but other methods such as a spinner method and a spray method may be used.

The conductive thin film 29 made of a fine particle film
As a film forming method, there may be used, for example, a vacuum evaporation method, a sputtering method, or a chemical vapor deposition method other than the method of applying the organometallic solution used in the present embodiment.

(3) Next, as shown in FIG. 7C, an appropriate voltage is applied between the element electrodes 27 and 28 from the forming power source 32 to perform the energization forming process, and To form

The energization forming treatment is to energize the conductive thin film 29 made of a fine particle film, to appropriately break, deform, or alter a part of the conductive thin film 29 to change into a structure suitable for emitting electrons. This is the process that causes In a portion of the conductive thin film made of the fine particle film that has been changed to a structure suitable for emitting electrons (that is, the electron emitting portion 30), an appropriate crack is formed in the thin film. Note that the electrical resistance measured between the device electrodes 27 and 28 is significantly increased after the formation, as compared to before the electron emission portion 30 is formed.

FIG. 8 shows an example of an appropriate voltage waveform applied from the forming power supply 32 in order to explain the energization method in more detail. When forming a conductive thin film made of a fine particle film, a pulsed voltage is preferable,
In the case of the present embodiment, as shown in FIG.
Was applied continuously at a pulse interval T2.
At that time, the peak value Vpf of the triangular wave pulse was sequentially increased. A monitor pulse Pm for monitoring the state of formation of the electron-emitting portion 30 was inserted between triangular-wave pulses at appropriate intervals, and the current flowing at that time was measured by an ammeter 33.

In this embodiment, for example, 10 ⁻³ T
In a vacuum atmosphere of about orr, for example, the pulse width T1 is 1 millisecond, and the pulse interval T2 is 10 milliseconds.
The peak value Vpf was increased by 0.1 [V] per pulse. Then, the monitor pulse Pm was inserted once every five 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 electric resistance between the device electrodes 27 and 28 becomes 1 × 10 ⁶ Ω, that is, when the current measured by the ammeter 33 when the monitor pulse is applied becomes 1 × 10 ⁻⁷ A or less, The process was completed by energization related to the forming process.

The above method is a preferable method for the surface conduction electron-emitting device of the present embodiment. For example, the design of the surface conduction electron-emitting device such as the material and thickness of the fine particle film or the element electrode interval L is changed. In such a case, it is desirable to appropriately change the energization conditions accordingly.

(4) Next, as shown in FIG.
An appropriate voltage is applied from the activation power supply 34 between the device electrodes 27 and 28, and the activation process is performed to improve the electron emission characteristics.

The energization activation process is a process in which energization is performed under appropriate conditions to the electron-emitting portion 30 formed by the energization forming process, and carbon or a carbon compound is deposited in the vicinity thereof. In FIG. 7D,
A deposit made of carbon or a carbon compound is schematically shown as the member 31. Note that by performing the energization activation process, the emission current at the same applied voltage can be typically increased by 100 times or more as compared with before the energization activation process.

Specifically, by periodically applying a voltage pulse in a vacuum atmosphere in the range of 10 ^-1 to 10 ^-4 Pa, carbon or carbon originating from an organic compound existing in the vacuum atmosphere is obtained. The carbon compound is deposited. Sediment 3
Reference numeral 1 denotes one of single-crystal graphite, polycrystalline graphite, and amorphous carbon, or a mixture thereof, and has a film thickness of 500 Å or less, more preferably 300 Å or less.

In order to explain the energizing method in more detail, FIG. 9A shows an example of an appropriate voltage waveform applied from the activation power supply 34. In the present embodiment, the energization activation process is performed by periodically applying a rectangular wave having a constant voltage. Specifically, the voltage Vac of the rectangular wave is 14 [V], and the pulse width T3 is 1 [mm]. Second] and the pulse interval T4 is 10 [milliseconds]. Note that the above-described energization conditions are preferable conditions for the surface conduction electron-emitting device of the present embodiment, and when the design of the surface conduction electron-emitting device is changed, it is desirable to appropriately change the conditions accordingly.

Reference numeral 35 shown in FIG. 7D denotes an anode electrode for capturing an emission current Ie emitted from the surface conduction electron-emitting device.
7 is connected. When the activation process is performed after the substrate 13 is incorporated in the display panel, the phosphor screen of the display panel is used as the anode electrode 35. While a voltage is applied from the activation power supply 34, the emission current Ie is measured by the ammeter 37 to monitor the progress of the energization activation process, and control the operation of the activation power supply 34. FIG. 9B shows an example of the emission current Ie measured by the ammeter 37.
When the pulse voltage is started to be applied from the activation power supply 34, the emission current Ie increases with time, but eventually saturates and hardly increases. As described above, when the emission current Ie is substantially saturated, the application of the voltage from the activation power supply 34 is stopped, and the energization activation process ends.

The above-mentioned energization conditions are preferable conditions for the surface conduction electron-emitting device of the present embodiment, and when the design of the surface conduction electron-emitting device is changed, the conditions should be changed accordingly. desirable.

As described above, the planar surface conduction electron-emitting device shown in FIG. 5B was manufactured.

(Vertical Type Surface Conduction Emission Element) Next, another typical structure of a surface conduction type emission element in which an electron emission portion or its periphery is formed of a fine particle film, that is, a vertical type surface conduction emission device. The configuration of the element will be described.

FIG. 10 is a schematic sectional view for explaining the basic structure of the vertical type. In the figure, 38 is a substrate, 39 and 40 are device electrodes, 43 is an insulating step forming member, and 41 is an insulating step forming member. A conductive thin film using a fine particle film, 42 is an electron emitting portion formed by an energization forming process, and 44 is a thin film formed by an energization activation process.

The difference between the vertical type and the flat type described above is that one element electrode 39 is provided on the step forming member 43, and the conductive thin film 41 covers the side surface of the step forming member 43. On the point. Therefore, the element electrode interval L in the planar type shown in FIG. 4 is set as the step height Ls of the step forming member 43 in the vertical type. In addition, the substrate 3
8, the element electrodes 39 and 40, and the conductive thin film 41 using the fine particle film, the materials listed in the description of the flat type can be similarly used. The step forming member 43 is made of an electrically insulating material such as SiO ₂ .

Next, a method for manufacturing a vertical surface conduction electron-emitting device will be described. FIGS. 11A to 11E are cross-sectional views for explaining a manufacturing process.
Same as 0.

(1) First, as shown in FIG.
An element electrode 40 is formed on a substrate 38.

(2) Next, as shown in FIG. 13B, an insulating layer for forming a step forming member is laminated. The insulating layer may be formed by stacking, for example, SiO ₂ by a sputtering method, but another film forming method such as a vacuum evaporation method or a printing method may be used.

(3) Next, as shown in FIG. 13C, an element electrode 39 is formed on the insulating layer.

(4) Next, as shown in FIG. 14D, a part of the insulating layer is removed by using, for example, an etching method.
The device electrode 40 is exposed.

(5) Next, as shown in FIG. 17E, a conductive thin film 41 using a fine particle film is formed. For the formation, as in the case of the flat type, a film forming technique such as a coating method may be used.

(6) Next, as in the case of the flat type,
An energization forming process is performed to form an electron emission portion.
The energization forming process may be the same as the planar energization forming process described with reference to FIG.

(7) Next, as in the case of the flat type,
An energization activation process is performed to deposit carbon or a carbon compound near the electron emission portion. This energization activation process is shown in FIG.
What is necessary is just to perform the same process as the planar type energization activation process described using (d).

As described above, the vertical surface conduction electron-emitting device shown in FIG. 10 was manufactured.

(Characteristics of Surface Conduction Emission Device Used in Display Device) The element configuration and manufacturing method of the planar and vertical surface conduction electron-emitting devices have been described above. Next, the characteristics of the device used in the display device will be described. Is described.

FIG. 12 shows typical examples of (emission current Ie) versus (device applied voltage Vf) characteristics and (device current If) versus (device applied voltage Vf) characteristics of the devices used in the display device. . Note that the emission current Ie is significantly smaller than the device current If, and it is difficult to draw the same current on the same scale.
Since these characteristics are changed by changing design parameters such as the size and shape of the element, the two graphs are shown in arbitrary units.

The element used in the display device has the following three characteristics with respect to the emission current Ie.

First, when a voltage higher than a certain voltage (referred to as a threshold voltage Vth as shown) or more is applied to the element, the emission current Ie sharply increases. On the other hand, the threshold voltage Vth At a voltage lower than the above, the emission current Ie is hardly detected.

That is, the device is a nonlinear device having a clear threshold voltage Vth with respect to the emission current Ie.

Secondly, since the emission current Ie changes depending on the voltage Vf applied to the element, the emission current Ie varies with the voltage Vf.
You can control the size of e.

Third, since the response speed of the current Ie emitted from the device is faster than the voltage Vf applied to the device, the amount of charge of the electrons emitted from the device depends on the length of time during which the voltage Vf is applied. Can control.

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 pixels of a display screen, if the first characteristic is used, display can be performed by sequentially scanning the display screen. That is,
The driving element has a threshold voltage V according to a desired light emission luminance.
A voltage higher than th is appropriately applied, and a voltage lower than the threshold voltage Vth is applied to the non-selected elements. By sequentially switching the elements to be driven, the display screen can be sequentially scanned and displayed.

Further, by using the second characteristic or the third characteristic, the light emission luminance can be controlled, so that gradation display can be performed.

[0143]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

Example 1 In this example, first, a plurality of unformed surface conduction electron sources 14 were formed on a substrate 13. As the substrate 13, a blue sheet glass whose surface was cleaned was used, and the surface conduction electron-emitting device shown in FIG.
60 × 720 pieces were formed in a matrix.

The element electrodes 27 and 28 are Pt sputtered films, and the X-direction wiring 15 and the Y-direction wiring 16 are Ag wirings formed by a screen printing method. The conductive thin film 26 is made of P
It is a PdO fine particle film obtained by firing a d-amine complex solution.

The fluorescent film 20 serving as an image forming member
As shown in FIG. 6A, a stripe shape in which each color phosphor extends in the Y direction is adopted, and the black body 20a is provided not only between the color phosphors but also in the X direction so that pixels in the Y direction are provided. The shape used was such that the space was separated and a portion for installing the spacer 22 was added. First, the black body (conductor) 20
a was formed, and phosphors of each color were applied to the gaps to form a phosphor film 20. Black stripe (black body 20a)
As a material for the above, a material containing graphite as a main component, which is commonly used, was used. A slurry method was used to apply the phosphor to the face plate 19.

The inner side (electron source side) of the fluorescent film 20
Is formed by performing a smoothing process (usually called filming) on the inner surface of the fluorescent film 20 after the formation of the fluorescent film 20, and then performing vacuum deposition of Al. The face plate 19 may be provided with a transparent electrode on the outer surface side (between the glass substrate and the fluorescent film) of the fluorescent film 20 in order to further increase the conductivity of the fluorescent film 20, but in this embodiment, only the metal back is provided. Was omitted because sufficient conductivity was obtained.

In FIG. 2, the spacer 22 has been cleaned.
Insulating substrate 24 made of soda lime glass (height 3.
8mm, plate thickness 200μm, length 20mm)
Al _TwoO_ThreeCermet film 23a is formed by vacuum film forming method
Then, a film was formed. Cr-Al used in this example_TwoO_ThreeSirmi
The cut film is deposited in an argon atmosphere using a sputtering device.
Cr and Al_TwoO_ThreeTarget simultaneously.
And a film was formed.

At the time of this film formation, argon was added to the film formation chamber at 0.7.
The composition was adjusted by introducing Pa and changing the power applied to each target. Note that the value of the specific resistance indicates a value after a heat treatment at 500 ° C. for one hour to be described later.

After forming this sample as a first layer, an insulating film 23b was formed thereon as a second layer 23b while the film forming apparatus was kept in a vacuum. In this embodiment, the insulating film 23b is used.
As for the material, Cr ₂ O ₃ was selected. This was formed as follows. First, after forming a Cr-Al ₂ O ₃ cermet film of the first layer, as it is without being taken out of the vacuum chamber, forming a film of the second layer.

As the target, a sintered body of Cr ₂ O ₃ was used. Argon and oxygen were respectively applied to the film forming chamber at a partial pressure of 0.4.
Pa and 0.1 Pa were introduced. The power applied to the target was 3.8 W / cm ² , and the deposition time was 1 minute, whereby a chromium oxide layer having a thickness of about 2 nm was obtained. After this,
By performing the above-described heat treatment at 500 ° C. for one hour, the fabrication of the spacer 22 was completed. The film forming conditions of each sample, sample name and material name, their thickness, and specific resistance are shown below.

(Sample A) First layer: Cr—Al ₂ O ₃ , 200 nm, 1.2 × 10 ⁵ Ωcm Second layer: Cr ₂ O ₃ , 2 nm (after the frit sealing step) Input power: 3.8 W / cm ² during deposition gas introduced Ar: 0.4Pa O _2: 0.1Pa deposition time 2 minutes the spacer 22 has its to ensure electrical connection between the X-direction wiring 15 and the metal back 21 A low resistance electrode 25 made of Al was provided at the connection part. The electrode 25 is connected to the face plate 19 from the X-direction wiring by 150
μm, 1 from metal back to rear plate 17
The four surfaces of the spacer 22 were completely covered within the range of 00 μm.

Thereafter, a face plate 19 was disposed 3.8 mm above the electron source 14 via a support frame 18 on the side wall, and the joint between the rear plate 17, the face plate 19, the support frame 18 and the spacer 22 was fixed. The spacers 22 were fixed on the X-directional wiring 15 at equal intervals. The spacer 22 uses a conductive frit glass 26 containing silica spheres coated with Au on a black body 20a (line width 300 μm) on the face plate 19 side, so that conduction between the semiconductive film 23a and the face plate 19 is achieved. Secured. In a region where the metal back 21 and the spacer 22 are in contact with each other, a part of the metal back 21 is removed. The joint between the rear plate 17 and the support frame 18 was sealed by applying frit glass (not shown) and firing at 420 ° C. for 10 minutes or more in the atmosphere.

After completion as described above, the air was exhausted by a vacuum pump through an exhaust pipe, and after reaching a sufficiently low pressure,
A voltage is applied between the device electrodes 27 and 28 of the electron-emitting device 14 through the outer terminals Dx1 to Dxm and Dy1 to Dyn,
The electron emission portion 30 was formed by applying a current to the conductive thin film 29 (forming process). The forming process was performed by applying a voltage having a waveform shown in FIG.

Then, acetone was passed through the exhaust pipe to 0.133.
The pressure activation was carried out by introducing a vacuum vessel to a pressure of Pa and periodically applying voltage pulses to terminals Dx1 to Dxm and Dy1 to Dyn outside the vessel to deposit carbon or a carbon compound. . The energization was activated by applying a waveform as shown in FIG.

Next, while heating the whole container to 200 ° C., 1
After evacuating for 0 hour, the exhaust pipe was welded and sealed by heating the exhaust pipe with a gas burner at a pressure of about 10 ^-4 Pa.

Finally, in order to maintain the pressure after sealing,
Getter processing was performed.

In the image forming apparatus completed as described above, the external terminals Dx1 to Dx
m and Dy1 to Dyn, the scanning signal and the modulation signal of the image signal are applied from a signal generating means (not shown) to emit electrons, and the metal back 21 is emitted by applying a high voltage through a high voltage terminal Hv. The electron beam is accelerated so that electrons collide with the fluorescent film 20 and the phosphor 2
An image corresponding to the image signal was displayed by exciting and emitting 0b. The applied voltage Va to the high voltage terminal Hv is 1 to 5
kV, the applied voltage Vf between the device electrodes 27 and 28 is 14 V
And At this time, for the sample A of the spacer, there was no or very little beam shift near the spacer under the above-mentioned driving conditions, and the beam was in a range where there was no problem as a television image. The resistance temperature coefficient of the first layer Cr-Al ₂ O ₃ cermet film is -0.33 from -0.3, never to thermal runaway in the driving conditions.

[0159]

As described above, according to the present invention,
When forming spacers used in an image forming apparatus,
C on a semiconductive film having an appropriate resistance value
r_TwoO _ThreeInsulation with low secondary electron emission rate containing at least
A conductive material to a thickness of 6.9 nm or less.
More effects could be obtained.

In the image forming apparatus using this, the disturbance of the beam potential near the spacer is suppressed, and a clear image display without displacement between the position where the beam collides with the phosphor and the phosphor which should emit light is realized. It is possible.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view near a spacer of an image display device according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view of a spacer used in the present invention.

FIG. 3 is a perspective view of the image display device according to the embodiment of the present invention, in which a part of a display panel is cut away.

FIG. 4 is a plan view of a substrate of the multi-electron beam source used in the present embodiment.

FIGS. 5A and 5B are a plan view and a cross-sectional view, respectively, of a planar surface-conduction emission type electron-emitting device used in Examples.

FIG. 6 is a plan view illustrating a phosphor array of a face plate of the display panel.

FIG. 7 is a cross-sectional view showing a manufacturing process of the planar type surface conduction electron-emitting device.

FIG. 8 is an applied voltage waveform in the energization forming process.

FIG. 9 shows an applied voltage waveform (a) and a change (b) in the emission current Ie in the activation process.

FIG. 10 is a sectional view of a vertical surface conduction electron-emitting device used in an example.

FIG. 11 is a cross-sectional view showing a manufacturing process of the vertical type surface conduction electron-emitting device.

FIG. 12 is a graph showing typical characteristics of a surface conduction electron-emitting device used in an example.

FIG. 13 is an example of a conventionally known surface conduction electron-emitting device.

FIG. 14 is an example of a conventionally known FE element.

FIG. 15 is an example of a conventionally known MIM element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Conductive thin film 3 Electron emission part 4 Substrate 5 Emitter wiring 6 Emitter cone 7 Insulating layer 8 Gate electrode 9 Substrate 10 Lower electrode 11 Insulating layer 12 Upper electrode 13 Substrate 14 Cold cathode element 15 Row direction wiring 16 Column direction wiring 17 Rear plate 18 Side wall 19 Face plate 20 Fluorescent film 21 Metal back 22 Spacer 23 Conductive film 23a First layer (undercoat layer) 23b Second layer (cap layer) 24 Insulating substrate 25 Intermediate layer electrode 26 Conductive frit 27, 28 Device electrode 29 Conductive thin film 30 Electron emission portion 31 Thin film formed by current activation process 32 Forming power supply 33 Ammeter 34 Activation power supply 35 Anode electrode 36 DC high voltage power supply 37 Ammeter 38 Substrate 39 device electrode 40 device electrode 41 conductive thin film 42 electron emission part 43 Thin film formed by the difference forming member 44 energization activation

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masahiro Fushimi 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 5C032 AA01 BB16 CC10 CD06 5C036 EF01 EF06 EG02 EG50 EH06

Claims (9)

[Claims] 1. An image forming apparatus having a structure in which a substrate on which a plurality of electron-emitting devices are formed and a transparent substrate on which a light emitting material is formed are opposed to each other with a spacer interposed therebetween, wherein the spacer is a first layer on the surface of the base material. Covered with a semiconductive film, further covered with an insulating film containing Cr ₂ O ₃ as a second layer, and the thickness of the second layer insulating film is 0.8.
an image forming apparatus having a thickness of at least 6.9 nm. 2. The image forming apparatus according to claim 1, wherein a resistance value of the insulating film of the second layer covering the spacer is at least 10 ⁴ Ωm in volume resistance. Semiconductive film of claim 3 wherein said first layer is a film thickness of 10 nm to 1 m, a specific resistance of 10 ^-7 × Va ² ~10 ⁵ Ωm when the electron acceleration voltage was set to Va, 2. The image forming apparatus according to claim 1, wherein a positive or absolute value is a negative temperature coefficient of resistance of 1% or less. 4. The image forming apparatus according to claim 1, wherein a voltage is applied to both ends of the semiconductive film of the first layer so as to generate a potential difference between both ends of the spacer. 5. A driving wire for the electron-emitting device is provided on a substrate on which the plurality of electron-emitting devices are formed, and one end of the spacer is electrically connected to the driving wire. 2. The image forming apparatus according to 1. 6. The image forming apparatus according to claim 1, wherein an acceleration electrode for accelerating the electrons emitted to the transparent substrate is provided, and one end of the spacer is electrically connected to the acceleration electrode. . 7. The image forming apparatus according to claim 1, wherein said electron-emitting device is a surface conduction electron-emitting device. 8. A flat or cross-shaped, L-shaped, cylindrical substrate surface is coated with a semiconductive film as a first layer,
A spacer, which is covered with an insulating film containing Cr ₂ O ₃ as a second layer, and the thickness of the insulating film of the second layer is not less than 0.8 nm and not more than 6.9 nm. 9. The spacer according to claim 8, wherein the insulating film of the second layer has a volume resistance of 10 ⁴ Ωm or more in volume and is used for a display panel.