JP2000243220A - Electron source substrate and image forming apparatus using the same - Google Patents

Abstract

(57) [Problem] To prevent deterioration of an electron source substrate due to heat or the like and maintain a good image for a long time in an image forming apparatus. SOLUTION: In an electron source substrate in which a large number of electron-emitting devices composed of a pair of device electrodes formed on a substrate via a surface coat layer and a conductive thin film having an electron-emitting portion are arranged, the electron-emitting substrate is included in the surface coat layer. The amount of water to be used is 50 ppm or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an electron source substrate using an electron-emitting device and an image forming apparatus using the electron source substrate.

[0002]

2. Description of the Related Art Conventionally, as an image forming apparatus using an electron-emitting device, an electron source substrate on which a large number of cold cathode electron-emitting devices are formed and an anode substrate provided with a transparent electrode and a phosphor are opposed in parallel to each other. 2. Description of the Related Art A flat-type electron beam display panel that has been exhausted is known. In such an image forming apparatus, the one using a field emission type electron emitting element is, for example,
[I. Brodie, "Advanced Techn
ology: flat cold-cathode C
RTs ", Information Display,
1/89, 17 (1989)]. Further, a device using a surface conduction electron-emitting device is described in, for example, U.S. Pat. S. P. No. 5,066,883 and the like.

A flat type electron beam display panel is a cathode ray tube (cathode ray tu) widely used at present.
be: CRT) It is possible to reduce the weight and increase the screen size as compared with a display device, and to use other flat display panels such as a flat display panel using a liquid crystal, a plasma display, and an electroluminescent display. It is possible to provide a higher-luminance, higher-quality image as compared with. In particular, the surface-conduction electron-emitting device has a simple structure and is easy to manufacture, and does not go through a complicated manufacturing process utilizing photolithography technology like a field-emission electron-emitting device.
There is an advantage that an electron source substrate having a large number of elements arranged and formed over a large area can be manufactured. FIG. 8 and FIG.
This shows an example of an electron source substrate using a surface conduction electron-emitting device disclosed in Japanese Patent No. 42636. FIG. 8 shows a plan view of a part of the electron source. Here, 7 is an upper wiring, 6 is a lower wiring, 81 is a surface conduction electron-emitting device, and 8 is an interlayer insulating layer. FIG. 9 is a perspective view of the surface conduction electron-emitting device 81 shown in FIG. In FIG. 9, 91 is a substrate, 2 and 3 are device electrodes, 4 is a conductive thin film having an electron emitting portion, 5 is an electron emitting portion, and the device electrodes 2 and 3 are connected to a lower wiring 6 and an upper wiring 7, respectively. The lower wiring 6 and the upper wiring 7 are electrically insulated by the interlayer insulating layer 8. Here, a predetermined voltage is sequentially applied to the upper wiring 7 and the lower wiring 6 arranged in a matrix as a scanning signal and an information signal, respectively, so that a predetermined electron-emitting device located at the intersection of the matrix is selectively driven. it can.

[0004] Such an electron source substrate arranged in a matrix can be manufactured by using a relatively simple photolithography technique. However, when a larger substrate is formed, it is preferable to use a printing technique. In particular, as for the upper wiring to which a scanning signal is applied, as the number of elements connected to one line increases, the amount of current flowing through the wiring increases, and a voltage drop occurs due to wiring resistance. Is preferably as small as possible. Japanese Patent Application Laid-Open No. 08-180797 discloses a manufacturing method in which wirings and interlayer insulating layers are formed by a screen printing method. Regarding other members, for example,
Japanese Patent Application Laid-Open No. 9-17333 discloses a manufacturing method in which element electrodes are formed by an offset printing method or the like, and a method of forming a conductive thin film by an inkjet method is disclosed in JP-A-09-69334. It has been disclosed. By using these printing techniques, a large-area electron source substrate can be easily manufactured.

Next, a surface conduction electron-emitting device will be described. The surface conduction electron-emitting device utilizes a phenomenon in which an electron is emitted by passing a current through a small-area conductive thin film formed on a substrate in parallel with the film surface. As the surface conduction electron-emitting device, a device using a SnO ₂ thin film [M. I. Elinson, Radio En
g. Electrophys. , 10, 1290,
(1965)], an Au thin film [G. Ditmm
er, Thin Solid Films, 9, 31
7 (1972)], based on an In ₂ O ₃ / SnO ₂ thin film [M. Hartwell and C.M. G. FIG. Fons
ted, IEEE Trans. ED Conf. , 5
19 (1975)], and those using a carbon thin film [Hisashi Araki et al .: Vacuum, Vol. 26, No. 1, p. 22 (1983)] and the like have been reported, for example, Japanese Patent Application Laid-Open No. 02-56822.
Discloses a surface conduction electron-emitting device using a film of fine metal particles such as palladium oxide.

In manufacturing a surface conduction electron-emitting device, it is general that the electron-emitting portion 5 is formed on the conductive thin film 4 by an energization process called forming. Forming means applying a DC voltage or a very slowly increasing voltage, for example, about 1 V / min, to both ends of the conductive thin film 4 and energizing the conductive thin film 4 to locally break, deform or alter the conductive thin film 4 and form a crack. Processing. Then, after the forming process is performed, a voltage is applied to the conductive thin film 4 and a current is caused to flow through the element, thereby emitting electrons from the vicinity of the crack. At this time, a portion from which electrons are emitted is referred to as an electron emitting portion 5.

Further, for example, Japanese Patent Application Laid-Open No. 07-235255
As disclosed in Japanese Patent Application Laid-Open Publication No. H10-209, a process called an activation process is performed on an element that has completed forming, so that better electron emission can be obtained. The activation step can be performed by repeatedly applying a pulse voltage to the device in an atmosphere containing an organic substance gas, similarly to the forming treatment, and carbon or a carbon compound is removed from the organic substance present in the atmosphere on the element. And the device current If and the emission current Ie are significantly increased.

A surface conduction electron-emitting device manufactured through such a process has sufficient electron emission characteristics as an electron source applicable to an image forming apparatus such as a flat panel display.

Accordingly, as described above, a large-area image forming apparatus, for example, a large-screen flat panel display is manufactured by manufacturing a large-area electron source substrate composed of surface conduction electron-emitting devices by using the printing technique. Can be realized.

[0010]

However, when an electron-emitting device having a sufficient amount of electron emission, a sufficient life, and stability is formed on a large-area electron source substrate, there are the following problems. In order to manufacture a large-area electron source substrate at low cost, it is necessary to reduce the cost of the members to be used, and soda-lime glass generally called blue plate glass is preferably used as the base. However, in a surface conduction electron-emitting device, since the electron-emitting portion is formed in contact with the surface of the substrate, heat and an electric field generated when the device is driven are transmitted to the surface of the soda-lime glass, and thermal deformation or deformation of the substrate is caused. The migration of sodium ions and the precipitation of sodium metal and sodium compounds are likely to occur. Deformation of the substrate in the vicinity of the element causes a change in the element structure, and precipitation of sodium changes not only the structure but also the electrical properties, which causes fluctuation and deterioration of the electron emission characteristics. Therefore, Japanese Patent Application Laid-Open No. 01-27
As disclosed in Japanese Patent No. 9538, it is desirable to form a surface coat layer on the surface of a soda lime glass with a material containing silicon dioxide as a main component, and to form an element thereon.

However, this surface coat layer has a different water content depending on the material and the manufacturing method, and is not only molecular water but also an OH group incorporated in the form of a silanol group (≡Si—OH). If they are contained in a large amount, they are released to the outside of the substrate due to heat during driving or the like. In the surface conduction electron-emitting device, since the electron-emitting portion is formed in contact with the substrate surface, the emitted water may deteriorate the characteristics of the electron-emitting device.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, that is, the problem that the electron emission characteristics are degraded due to the release of water from the surface coat layer of the substrate. It is an object of the present invention to provide an image forming apparatus capable of preventing deterioration due to the above-mentioned factors and maintaining a good image for a long time.

[0013]

In order to achieve the above object, an electron source substrate according to the present invention has a pair of device electrodes and an electron emitting portion formed on a substrate made of glass or the like via a surface coat layer. An electron source substrate on which a large number of electron-emitting devices composed of a conductive thin film are arranged, wherein the amount of water contained in a surface coat layer is 50 ppm or less. However, in the present specification, the water includes not only molecular water but also structural water such as absorbed water, occluded water, and OH groups taken in the form of silanol groups.

Here, if the amount of water contained in the surface coat layer exceeds 50 ppm, water released to the outside of the substrate due to heat or the like generated during the activation processing or driving described later may affect the electron emission characteristics of the device. The effect is not negligible.

In the present invention, the electron-emitting device comprises a conductive thin film formed by heating and baking a material for forming a conductive thin film provided on the surface coat layer so as to connect between the pair of device electrodes, and thereafter, It can be created by providing an electron emission part by energization forming processing described in detail,
By an activation process described later, carbon and / or a carbon compound may be deposited on the element such as in the vicinity of the electron emission portion.

Further, in the electron source substrate of the present invention, it is desirable that the electron-emitting device is a surface conduction electron-emitting device.

In the electron source substrate of the present invention, usually, a plurality of electron-emitting devices in which device electrodes at both ends of each device are connected to metal wiring are arranged, and are configured to emit electrons according to an input signal. You. In this case, a plurality of rows of electron-emitting devices are arranged in parallel, and a modulation means for modulating an input signal is provided to emit electrons from any electron-emitting device on the substrate. It is possible to do. More specifically, a pair of element electrodes of the electron-emitting device is connected to the X-direction metal wiring and the Y-direction metal wiring at each intersection of the m X-direction metal wirings and the n Y-direction metal wirings electrically insulated from each other. Direction metal wiring,
It is configured such that the electron-emitting devices are arranged in a matrix.

Further, an image forming apparatus of the present invention is an image forming apparatus comprising the above-mentioned first electron source substrate of the present invention.

As described above, the present invention provides an electron source substrate provided with a surface coat layer having a low water content in order to prevent deterioration of the electron-emitting device due to the release of water from the surface coat layer of the substrate. An embodiment of the present invention, which relates to an image forming apparatus used, will be described in detail below.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram (plan view) showing an example of the electron source substrate of the present invention, and shows only a part of the electron source substrate. FIG. 2A is an enlarged bird's-eye view of one electron-emitting device of the electron source substrate shown in FIG. FIG.
FIG. 2B is a cross-sectional view taken along the line AA ′ in FIG.

1 and 2, 1 is a substrate, 2 and 3 are device electrodes, 4 is a conductive thin film, 5 is an electron emitting portion, 6
And 7 are wirings connected to the device electrodes 2 and 3, respectively, 8 is an interlayer insulating layer for electrically insulating the wirings 6 and 7, and 9 is a surface coat layer. The wirings 6 and 7 may be referred to as a Y-directional wiring and an X-directional wiring, respectively, in view of the coordinates in FIG. 1, and may be referred to as a lower wiring and an upper wiring, respectively, depending on the positional relationship with the insulating layer 8.

As the base 1, for example, blue plate glass, N
glass with reduced impurity content such as a, quartz glass,
Ceramics such as alumina are used, but soda lime glass, which is generally called blue plate glass, is preferably used because it is inexpensive. Since the soda lime glass substrate contains sodium, the substrate can be formed using a float method that can be mass-produced. For example, a large-sized substrate having a diagonal width of 1 m or more can be produced at low cost. The surface coat layer 9 is a coating layer that has a role of preventing diffusion of sodium from the substrate 1 to the electron-emitting device and a role of making it difficult to transmit heat generated when a current flows to the electron-emitting device to the substrate 1. In order to satisfy the above role, the surface coat layer 9
A coating layer containing silica as a main component can be preferably used. Here, silica means SiO ₂ , Si
O, and mixtures thereof. Among them, SiO ₂
Or a layer composed of phosphorus-doped silica glass (PGS) containing several wt% of phosphorus in these layers is more preferably used. When these coating layers are formed to a thickness of 500 nm or more, diffusion of sodium is effectively stopped. Further, the water content in this surface coat layer is 50 ppm or less.

The term "water content" as used herein means not only adsorbed water molecules but also silanol groups (S) which terminate the outermost surface of the surface coat layer 9 and are incorporated in the surface coat layer.
i-OH) and OH groups. Here, the water content is a water molecule (H ₂ O) relative to the total composition of the surface coat layer.
And the weight ratio of OH groups.

Materials for the opposing device electrodes 2 and 3 include:
It is preferable to have a stable conductivity even after the subsequent heat treatment step. For example, a metal thin film mainly composed of a noble metal such as Au, Pt, Pd or an alloy thereof is used.

It is preferable that the film thickness of the device electrodes 2 and 3 is about several tens of nm, because it has sufficient conductivity and the step coverage of the conductive thin film 4 is good.

When the noble metal thin film is formed on the surface coat layer 9, sufficient adhesion strength may not be obtained. At this time, a base metal material such as Ti or Cr may be used as an undercoat to increase the adhesion between the device electrodes 2 and 3 and the surface coat layer 9. As the conductive thin film 4, a fine particle film composed of fine particles is preferably used in order to obtain good electron emission characteristics.

Since the thermal stability of the conductive thin film 4 is an important parameter that governs the lifetime of the electron emission characteristics, it is desirable to use a material having a higher melting point as the material of the conductive thin film 4. However, in general, the higher the melting point of the conductive thin film 4 is, the more difficult it is to carry out energization forming, which will be described later. further,
The resulting electron-emitting portion may have a problem that the applied voltage (threshold voltage) at which electrons can be emitted increases.

Therefore, the material of the conductive thin film 4 is preferably selected from those having a moderately high melting point and capable of forming a good electron emission portion with a relatively low forming power.

Under the above-described conditions, PdO can be easily formed into a thin film by baking an organic palladium compound in the air, has relatively low electric conductivity because of being a semiconductor, has low power for forming, and has a high efficiency in forming an electron emitting portion. Alternatively, thereafter, it can be easily reduced to metal palladium, so that the film resistance can be reduced. For example, it can be used as a material suitable for the conductive thin film 4.

The film thickness is set in consideration of the step coverage of the device electrodes 2 and 3, the resistance value between the device electrodes 2 and 3, the forming conditions described later, and the like. A fine particle film of several nm to several tens nm composed of fine particles of several nm is preferably used.

The electron emitting portion 5 is a high resistance portion such as a crack formed on a part of the conductive thin film 4 and has conductive fine particles having a particle size of several nm to several tens nm, that is, inside the crack. In some cases, PdO or PdO has a large number of fine particles of Pd metal generated by reduction of PdO, and depends on the manufacturing method such as the thickness of the conductive thin film 4 and the energization processing conditions described later.

Further, the conductive fine particles are formed of a conductive thin film 4.
Are the same as some or all of the elements of the material constituting.

Further, a part of the electron emitting portion 5 and furthermore, the conductive thin film 4 near the electron emitting portion 5 has carbon and / or a carbon compound through an activation step described later. With respect to the role of the carbon and / or carbon compound, it is presumed that the material constituting the electron-emitting portion 5 controls the electron-emitting characteristics.

The wirings 6 and 7 are for supplying power to a plurality of electron-emitting devices as shown in FIG.

The m X-direction wirings 7 are DX1, DX2,
.. DXm, n Y-direction wirings 6 are DY1, DY
, DYn, and the materials, film thicknesses, wiring widths, etc. are designed so that a substantially uniform voltage is supplied to a large number of electron-emitting devices. These m X-direction wirings 7
An interlayer insulating layer 8 is provided between the n-directional wirings 6 and n and electrically separated to form a matrix wiring (m and n are both positive integers).

The wirings 6 and 7 are preferably made of a metal having stable conductivity even after a heat treatment step, similarly to the device electrodes 2 and 3, but in particular, a printing method which can be formed on a large-area substrate at low cost is applied. What can be done is desirable. The metal paste obtained by patterning the metal paste by screen printing and heat-treating is suitable for forming large-area, low-resistance wiring with a thickness of several microns or more. Ag, Cu, A that can be obtained at low cost
u, that is, A obtained by heat-treating
g, Cu, and Au are preferably used. Further, a mixture of these metal pastes, or an Ag paste containing Pd, for example, may be used.

The shape, material, film thickness, and manufacturing method of the interlayer insulating layer 8 can be appropriately set so as to withstand the potential difference at the intersection of the wiring 6 and the wiring 7. Usually, a thick glass layer obtained by printing a glass paste is used.

In the configuration shown in FIG. 1, that is, in a matrix arrangement, a scanning signal (not shown) for applying a scanning signal for selecting a row of electron-emitting devices arranged in the X direction is applied to the X-direction wiring 7. Means are connected, and the Y-direction wiring 6
Is connected to a modulation signal generating means (not shown) for modulating each column of the electron-emitting devices arranged in the Y direction according to an input signal.

The driving voltage applied to each electron-emitting device is:
It is supplied as a difference voltage between the scanning signal and the modulation signal applied to the element, and individual elements can be selected using a simple matrix wiring and can be independently driven.

On the other hand, in addition to the above, each of a large number of electron-emitting devices arranged in parallel is connected at both ends, and a large number of rows of electron-emitting devices are arranged. There is a ladder-like arrangement in which electrons from the electron-emitting devices are controlled and driven by a control electrode arranged above, but the present invention is not particularly limited by these arrangements.

Now, various methods are conceivable as a method of manufacturing the electron source substrate of the present invention, one example of which is shown in FIG. Hereinafter, a method for manufacturing an electron source substrate according to the present invention will be described in order with reference to FIGS. 1) After sufficiently washing the glass substrate 1 with a detergent, pure water and an organic solvent, the water content is 50 ppm by a sputtering method or the like.
The following surface coat layer 9 is formed (FIG. 3A). At this time, quartz glass (SiO ₂ ) having a low water content is used as a target material used for sputtering. In particular, those having a water content of 10 ppm or less are preferable. For example, the classification of quartz glass (Asakura Shoten: Glass Handbook, 1005)
Type I and Type IV on page) can be used. I
The mold is an electrofused glass, and the mold IV is a composition obtained by synthesizing SiCl ₄ gas in oxygen plasma. The method of forming the surface coat layer 9 is not limited to the sputtering method as long as the above-mentioned water content is satisfied.
It may be formed by an organometallic coating material such as an electron beam evaporation method and a CVD method. Further, the surface coat layer 9 having a high water content may be subjected to a heating step at 400 ° C. or more in a vacuum to reduce water contained in the surface coat layer 9.

2) Subsequently, after the device electrode material is deposited on the substrate 1 on which the surface coat layer 9 is formed by a vacuum evaporation method, a sputtering method or the like, the device electrodes 2 and 3 are formed by photolithography (FIG. 3). (B)). The device electrodes 2
The formation of No. 3 can also be formed by applying an organometallic paste and firing after using a printing technique such as offset printing.

3) On the substrate 1 on which the device electrodes 2 and 3 are formed,
A conductive paste pattern is formed by a screen printing method, and the conductive paste pattern is baked to form a lower wiring 6 made of metal (FIG. 3C).

4) Further, an interlayer insulating layer 8 is formed at a desired position on the lower wiring 6, that is, at a position crossing the upper wiring 7 to be formed in a subsequent step (FIG. 3D). The interlayer insulating layer 8 can also be formed by forming a glass paste pattern by a screen printing method and firing the glass paste pattern. When it is desired to increase the film thickness in order to impart sufficient insulation to the interlayer insulating layer 8, the above printing and firing can be repeated a desired number of times.

5) Subsequently, the upper wiring 7 is formed so as to cross on the interlayer insulating layer 8 formed on the lower wiring 6 (FIG. 4A). Similarly to the lower wiring 6, the upper wiring 7 can be formed by forming a pattern of a conductive paste and firing the pattern of the conductive paste.

6) Device electrode 2 provided on base 1
A film made of an organometallic compound is formed by applying and drying a solution of an organometallic compound between the substrate and the device electrode 3. Thereafter, the organometallic compound film is subjected to a heating and baking treatment,
The conductive thin film 4 is formed by patterning by lift-off, etching, or the like (FIG. 4B). Here,
Although the description has been given by using the method of applying the organic metal solution, the present invention is not limited thereto, and the conductive thin film 4 may be formed by a vacuum deposition method, a sputtering method,
It may be formed by a CVD method, a dispersion coating method, a dipping method, a spinner method, an inkjet method, or the like.

7) Subsequently, when an energization process called forming is performed between the device electrodes 2 and 3, that is, between the wirings 6 and 7 by applying a pulse-like voltage or a rising voltage from a power supply (not shown), the conductivity is increased. An electron emitting portion 5 having a changed structure is formed at the portion of the conductive thin film 4 (FIG. 4C). The portion where the conductive thin film 4 is locally broken, deformed or deteriorated by the energization treatment and the crack structure is formed is referred to as an electron emitting portion 5.

In the forming process, there are a case where a pulse having a constant pulse peak value is applied and a case where a voltage pulse is applied while increasing the pulse peak value. First, FIG. 5A shows a voltage waveform when a pulse having a pulse crest value of a constant voltage is applied.

In FIG. 5A, T1 and T2 are the pulse width and pulse interval of the voltage waveform, respectively, and T1 is 1 μsec.
c to 10 msec, T2 is 10 μsec to 100 msec
As c, the peak value of the triangular wave (peak voltage at the time of forming) is appropriately selected.

Next, FIG. 5B shows a voltage waveform when a voltage pulse is applied while increasing the pulse peak value.

In FIG. 5B, T1 and T2 are the pulse width and pulse interval of the voltage waveform, respectively, and T1 is 1 μs
c to 10 msec, T2 is 10 μsec to 100 msec
c, the peak value of the triangular wave (peak voltage at the time of forming) is increased by, for example, about 0.1 V steps.

In the forming process, a pulse voltage of, for example, about 0.1 V is inserted between the forming pulses so that the conductive thin film 2 is not locally broken or deformed, and the element current is measured. The process ends when the current decreases below a predetermined value.

8) Next, an activation process is performed on the element for which the forming has been completed, if desired. The activation process is performed by applying a pulse voltage in the same manner as the above-described forming process in an atmosphere containing an organic substance. Is obtained by introducing In the case where a vacuum envelope is formed using an electron source substrate as in an image forming apparatus described later, the activation process can be performed by introducing an organic substance into the vacuum envelope.

Organic substances suitable for the activation treatment include alkanes, alkenes, aliphatic hydrocarbons of alkynes, aromatic hydrocarbons, alcohols, aldehydes, ketones, amines, nitriles, phenols, carboxylic acids. And organic acids such as sulfonic acid. Specific examples thereof include compositions of saturated hydrocarbons represented by C _n H _{2n + 2} such as methane, ethane, and propane, and compositions of C _n H _2n such as ethylene and propylene. Unsaturated hydrocarbon represented by the formula, benzene, toluene, methanol, ethanol, formaldehyde, acetaldehyde, acetone, methyl ethyl ketone, methylamine, ethylamine, phenol, benzonitrile,
Acetonitrile, formic acid, acetic acid, propionic acid and the like can be used.

By this treatment, carbon or a carbon compound is deposited on the device from organic substances existing in the atmosphere,
The element current If and the emission current Ie change remarkably. The end of the activation step is determined based on the device currents If and / or
Alternatively, the measurement is appropriately performed while measuring the emission current Ie. The pulse width, pulse interval, pulse crest value, and the like are set as appropriate.

Carbon and carbon compounds include, for example, graphite (including so-called HOPG, PG, and GC.
OPG is a crystal structure of almost perfect graphite, PG is a crystal having a crystal grain of about 20 nm and a slightly disordered crystal structure, GC
Indicates that the crystal grain is about 2 nm and the disorder of the crystal structure is further increased. ), Amorphous carbon (refers to amorphous carbon and a mixture of amorphous carbon and the microcrystals of graphite).

9) The electron source substrate thus manufactured is preferably subjected to a stabilization step. This step is a step of exhausting a residue of the organic substance introduced during the activation treatment. The pressure in the vacuum vessel is preferably 1 to 3 × 10 ⁻⁷ Torr or less, and more preferably 1 × 10 ⁻⁸ Torr or less.
It is preferable to use a vacuum exhaust device that does not use oil so that the oil generated from the device does not affect the characteristics of the element. Specifically, a vacuum exhaust device such as a sorption pump or an ion pump can be used. Further, when the inside of the vacuum vessel is evacuated, it is preferable that the entire vacuum vessel is heated so that the organic substance molecules adsorbed on the inner wall of the vacuum vessel and the electron source substrate are easily evacuated. The heating condition at this time is desirably 80-250 ° C., preferably 150 ° C. or more, and it is desirable that the heating be performed for as long as possible. However, the heating condition is not particularly limited to this condition. This is performed under conditions appropriately selected according to various conditions.

The atmosphere at the time of driving after performing the stabilization step is preferably the same as the atmosphere at the end of the stabilization treatment, but is not limited to this. If the organic substance is sufficiently removed, Even if the pressure itself increases somewhat, it is possible to maintain sufficiently stable characteristics.

By adopting such a vacuum atmosphere, the deposition of new carbon or carbon compound can be suppressed.
As a result, the element current If and the emission current Ie are stabilized.

The above is the manufacturing process of the electron source substrate in the present invention. An example in which an image forming apparatus is configured by using the electron source substrate will be described below with reference to FIGS. FIG.
Is a basic configuration diagram of the image forming apparatus, and FIG. 7 is a fluorescent film.

In FIG. 6, reference numeral 61 denotes an electron source substrate on which a plurality of electron-emitting devices are arranged; 62, a rear plate on which the electron source substrate 61 is fixed; 67, a fluorescent film 65 on the inner surface of a glass substrate 64;
And a face plate on which a metal back 66 and the like are formed, and 63 is a support frame. The rear plate 62, the support frame 63, and the face plate 67 are coated with frit glass, and are heated at 400 to 500 ° C. in air or nitrogen at 400 to 500 ° C.
By baking for 0 minutes or more, sealing is performed to form the envelope 69.

The envelope 69 is composed of the face plate 67, the support frame 63, and the rear plate 62 as described above. However, since the rear plate 62 is provided mainly for the purpose of reinforcing the strength of the substrate 61, If the 61 itself has a sufficient strength, the separate rear plate 62 is unnecessary, and the substrate 6
1, a support frame 63 is directly sealed, and a face plate 67,
The envelope 69 may be constituted by the support frame 63 and the substrate 61.

On the other hand, by installing a support (not shown) called a spacer between the face plate 67 and the rear plate 62, an envelope 69 having sufficient strength against the atmospheric pressure may be formed. it can.

FIG. 7 shows a fluorescent film. The fluorescent film 65 is made of only a phosphor in the case of monochrome, but is made of a black conductive material 71 called a black stripe or a black matrix depending on the arrangement of the phosphor and a phosphor 72 in the case of a color fluorescent film. . The purpose of providing the black stripes and the black matrix is to make the mixed portions of the three primary color phosphors necessary for the color display between the respective phosphors 72 black so that color mixing and the like are inconspicuous. In suppressing a decrease in contrast due to reflection of external light. The material of the black conductive material 71 in the black stripe or the like is not limited to a material mainly containing graphite, which is commonly used, as long as it is conductive and has little light transmission and reflection. is not.

The method of applying the fluorescent substance 72 to the glass substrate 64 is not limited to monochrome or color, but a precipitation method, a printing method, or the like is used. A metal back 66 is usually provided on the inner surface side of the fluorescent film 65. The purpose of metal back is
Improving the brightness by mirror-reflecting the light toward the inner surface side of the light emitted from the phosphor 72 toward the face plate 67, acting as an electrode for applying an electron beam accelerating voltage, This is to protect the phosphor 72 from damage caused by the collision of the generated negative ions. After the fluorescent film 65 is formed, the metal back 66 is subjected to a smoothing process (usually called filming) on the inner surface of the fluorescent film 65.
And then depositing Al using vacuum evaporation or the like.

The face plate 67 is further provided with a fluorescent film 6.
A transparent electrode (not shown) may be provided on the outer surface side of the fluorescent film 65 in order to increase the conductivity of the phosphor 5.

When the above-mentioned sealing is performed, in the case of color, the phosphors of each color must correspond to the electron-emitting devices, so that it is necessary to perform sufficient alignment.

The envelope 69 is connected to an exhaust pipe (not shown) to
After the degree of vacuum is set to about × 10 ⁻⁷ Torr, sealing is performed. In addition, getter processing may be performed to maintain the degree of vacuum after sealing the envelope 69. This is because the getter disposed at a predetermined position (not shown) in the envelope 69 is heated by a heating method such as resistance heating or high-frequency heating immediately before or after the envelope 69 is sealed. ,
This is a process for forming a deposition film. The getter is usually composed mainly of Ba or the like.
A vacuum degree of × 10 ^-5 or 1 × 10 ^-7 Torr is maintained.

In the image display device of the present invention completed as described above, a voltage is applied to each electron-emitting device through external terminals Dox1 to Doxm, Doy1 to Doyn, thereby emitting electrons. An image is displayed by applying a high voltage of several kV or more to the metal back 66 or a transparent electrode (not shown), accelerating the electron beam, colliding the electron beam with the fluorescent film 65, exciting and emitting light.

The configuration described above is a schematic configuration necessary for manufacturing a suitable image forming apparatus used for display and the like. For example, detailed portions such as materials of each member are limited to those described above. Instead, it is appropriately selected so as to be suitable for the purpose of the image apparatus.

[0071]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to specific examples, but the present invention is not limited to these examples, and each element within a range in which the object of the present invention is achieved. This also includes those in which substitutions or design changes have been made.

[Embodiment 1] The basic structure of an electron source substrate according to this embodiment is the same as that shown in FIGS. The method for manufacturing the electron source substrate according to the present embodiment is shown in FIGS. Hereinafter, a basic configuration and a manufacturing method of the electron source substrate and the image forming apparatus according to the present embodiment will be described with reference to FIGS. 1, 2, 3, and 4. FIG. Although FIGS. 3 and 4 show the manufacturing process in the vicinity of one electron-emitting device in an enlarged manner for the sake of simplicity, the present embodiment is an example of an electron source substrate in which a large number of electron-emitting devices are arranged in a simple matrix.

Step-a A 1.0 μm-thick SiO ₂ film as a surface coat layer 9 was sputtered on a cleaned blue plate glass substrate 1 using quartz glass (water content of 10 ppm or less) produced by an electrofusion method as a target. After applying and baking a resist material on the substrate formed by the method, a resist pattern having a desired opening was formed. In addition, as a result of analyzing the water content of the surface coat layer 9 by infrared spectrophotometry, the water content (the content of H ₂ O and OH groups) was 50 ppm or less.

Step-b Next, a 5 nm-thick T
i, Pt having a thickness of 50 nm was sequentially deposited. Thereafter, the pattern of the device electrodes 2 and 3 is formed of photoresist, the Pt / Ti deposited layer other than the pattern of the device electrodes 2 and 3 is removed by dry etching, and finally the photoresist pattern is removed. A few were formed.

Step-c The pattern of the lower wiring 6 is formed on the substrate 1 on which the surface coat layer 9 and the device electrodes 2 and 3 are formed by screen printing.
Formed using a paste, dried and fired at 500 ° C.
The lower wiring 6 having a desired shape made of Ag was formed.

Step-d Next, a pattern of the interlayer insulating layer 8 is formed by screen printing using a glass paste.
Was fired. In order to obtain a sufficient insulating property, printing, drying and baking of the glass paste were repeated again to form the interlayer insulating layer 8 of glass having a desired shape.

Step-e The pattern of the upper wiring 7 is formed by screen printing using an Ag paste so as to intersect with the lower wiring 6 at the portion where the interlayer insulating layer 8 is formed, dried, and fired at 500 ° C. Then, the upper wiring 7 of a desired shape made of Ag was formed. Through the above steps, a substrate in which the element electrodes 2 and 3 were connected in a matrix by the wirings 6 and 7 was formed.

Step-f Next, a conductive thin film 4 was formed so as to extend between the gaps between the device electrodes 2 and 3. The formation of the conductive thin film 4 was performed by applying an organic palladium solution to a desired position by an inkjet method and performing a heating and baking treatment at 350 ° C. for 30 minutes. The conductive thin film 4 thus obtained was composed of fine particles containing PdO as a main component, and had a thickness of about 10 nm.

Through the above steps, the surface coat layer 9, the lower wiring 6, the interlayer insulating layer 8, the upper wiring 7, the element electrodes 2,
3 and a conductive thin film 4 were formed to produce an electron source substrate.

Hereinafter, an example in which an image forming apparatus is configured using the electron source substrate of this embodiment will be described with reference to FIGS. After fixing the electron source substrate 61 manufactured as described above on the rear plate 62, a face plate 67 (a fluorescent film 65 and a metal back 66 are formed on the inner surface of the glass substrate 64) 5 mm above the electron source substrate 61. Is disposed via the support frame 63, and the face plate 6
7. A frit glass was applied to the joint between the support frame 63 and the rear plate 62, and was baked at 400 ° C. in the air for 10 minutes to seal. Also, the electron source substrate 6 on the rear plate 62
1 was also fixed with frit glass.

The fluorescent film 65 is composed of only a phosphor in the case of monochrome, but in this embodiment, the phosphor is formed in a stripe shape, a black stripe is formed first, and each color phosphor is applied to the gap. Then, a fluorescent film 65 was manufactured. As the material for the black stripe, a material mainly containing graphite, which is generally used, was used. A slurry method was used to apply the phosphor to the glass substrate 64.

A metal back 66 is usually provided on the inner side of the fluorescent film 65. The metal back 66 was manufactured by performing a smoothing process (usually called filming) on the inner surface of the fluorescent film 65 after the fluorescent film 65 was manufactured, and then performing vacuum deposition of Al. In order to further enhance the conductivity of the fluorescent film 65, a fluorescent film 65
In some cases, a transparent electrode (not shown) may be provided on the outer surface side, but in this embodiment, the metal back 66 alone provided sufficient conductivity, and was omitted.

At the time of performing the above-mentioned sealing, in the case of color, since the phosphors of each color and the electron-emitting devices must correspond to each other, sufficient alignment was performed.

The atmosphere in the glass container completed as described above is evacuated by a vacuum pump through an exhaust pipe (not shown), and after reaching a sufficient degree of vacuum, external terminals Dox1 to Doxm and Doy1 to Doyn. A voltage was applied to the device electrodes 2 and 3 through the process to form the conductive thin film 4. The voltage waveform of the forming process is the same as that shown in FIG. In this embodiment, T1 is 1 msec,
T2 was set to 10 msec and performed under a vacuum atmosphere of about 1 × 10 ⁻⁵ Torr.

Next, after exhausting was continued until the pressure in the panel reached the level of 10 ^-8 Torr, organic substances were introduced into the panel from the exhaust pipe of the panel so that the total pressure became 1 × 10 ^-6 Torr. Introduced and maintained. Outer container terminal Dox1 to Do
A pulse voltage having a peak value of 15 V was applied between the device electrodes 2 and 3 through xm and Doy1 to Doyn to perform an activation process. In this manner, the forming and activation processes were performed to form the electron emission portions 5.

Next, the gas was evacuated to a pressure of about 10 ^-6 Torr, and an exhaust pipe (not shown) was heated by a gas burner to be welded to seal the envelope. Finally, in order to maintain the pressure after sealing, getter processing was performed by a high-frequency heating method.

In the image display device of the present embodiment completed as described above, each of the electron-emitting devices has a terminal Dox outside the container.
1 to Doxm and Doy1 to Doyn, respectively, apply a scanning signal and a modulation signal from signal generation means (not shown) to emit electrons, thereby causing the high voltage terminal 6
Through 8, a high voltage of 5 kV or more was applied to a metal back 66 or a transparent electrode (not shown) to accelerate the electron beam, collide with the fluorescent film 65, and excite and emit light to display an image.

The image display device of this example was able to display a good image stably over a long period of time at a luminance (about 150 fL) sufficiently satisfactory as a television.

[Embodiment 2] The basic configuration of an electron source substrate according to the present embodiment is the same as that of Embodiment 1. Step-a A 1.0 μm-thick SiO ₂ film was formed as a surface coat layer 9 on a cleaned blue glass substrate 1 by a sputtering method using quartz glass (water content: 100 ppm) produced by a flame melting method as a target. After the substrate was heated in a vacuum to perform a dehydration treatment, a resist material was applied and baked, and then a resist pattern having a desired opening was formed.
In addition, as a result of analyzing the water content of the surface coat layer 9 by infrared spectrophotometry, the water content was 50 ppm or less.

Step-b Next, a 5 nm-thick T
i, Pt having a thickness of 50 nm was sequentially deposited. Thereafter, the pattern of the device electrodes 2 and 3 is formed of photoresist, the Pt / Ti deposited layer other than the pattern of the device electrodes 2 and 3 is removed by dry etching, and finally the photoresist pattern is removed. A few were formed.

Step-c The pattern of the lower wiring 6 was formed on the substrate 1 on which the surface coat layer 9 and the device electrodes 2 and 3 were formed by screen printing.
Formed using a paste, dried and fired at 500 ° C.
The lower wiring 6 having a desired shape made of Ag was formed.

Step-d Next, a pattern of the interlayer insulating layer 8 is formed by screen printing using a glass paste.
Was fired. In order to obtain a sufficient insulating property, printing, drying and baking of the glass paste were repeated again to form the interlayer insulating layer 8 of glass having a desired shape.

Step-e The pattern of the upper wiring 7 is formed by screen printing using an Ag paste so as to intersect with the lower wiring 6 at the portion where the interlayer insulating layer 8 is formed, dried, and fired at 500 ° C. Then, the upper wiring 7 of a desired shape made of Ag was formed.

Through the above steps, a substrate having the device electrodes 2 and 3 connected in a matrix by the wirings 6 and 7 was formed.

Step-f Next, a conductive thin film 4 was formed so as to extend between the gaps between the device electrodes 2 and 3. The formation of the conductive thin film 4 was performed by applying an organic palladium solution to a desired position by an inkjet method and performing a heating and baking treatment at 350 ° C. for 30 minutes.

The conductive thin film 4 thus obtained was composed of fine particles containing PdO as a main component, and had a thickness of about 10 nm. Through the above steps, the surface coat layer 9, the lower wiring 6, the interlayer insulating layer 8, the upper wiring 7, the element electrodes 2, 3, and the conductive thin film 4 were formed on the base 1, and an electron source substrate was manufactured.

Thereafter, an image forming apparatus was constructed using the electron source substrate of the present embodiment in the same manner as in the first embodiment. Even in the image display apparatus of the present embodiment, the luminance (approximately 150 fL ), A good image could be stably displayed for a long time.

Comparative Example 1 In this comparative example, the same steps as in Example 2 were performed except that the surface coat layer was not dehydrated by heating in vacuum.

Steps a to e A SiO ₂ film having a thickness of 1.0 μm was formed as a surface coat layer 9 on a cleaned blue glass substrate 1 using quartz glass (water content: 100 ppm) produced by a flame melting method as a target. Example 2 using a substrate formed by the sputtering method
By carrying out the same steps as above, the lower wiring 6, the interlayer insulating layer 8, the upper wiring 7, the device electrodes 2, 3 and the conductive thin film 4 were formed on the base 1, and an electron source substrate was manufactured. As a result of analyzing the water content of the surface coat layer 9 by infrared spectrophotometry, the water content was 100 ppm. Further, similarly to Examples 1 and 2, after sealing was performed, forming and activation treatments were performed to form gaps 5.

Thereafter, as in Embodiments 1 and 2, an image forming apparatus was constructed using the electron source substrate of this embodiment. In the image display apparatus of this comparative example, it was sufficient to display an image for a long time. No good electron source characteristics were obtained, and the brightness gradually decreased.

[0101]

As described above, according to the present invention, by maintaining the water content of the surface coat layer used for improving the electron emission characteristics to 50 ppm or less, a good image can be maintained for a long time. The resulting large-screen flat image forming apparatus, for example, a color flat television can be realized.

[Brief description of the drawings]

FIG. 1 is a plan view showing one example of an electron source substrate of the present invention.

FIG. 2 is a bird's-eye view near the electron-emitting device of the electron source substrate of the present invention.

FIG. 3 is a cross-sectional view of the electron source substrate of the present invention in the vicinity of an electron-emitting device.

FIG. 4 is a diagram for explaining a basic method for manufacturing an electron source substrate according to the present invention.

FIG. 5 is a diagram showing an example of a voltage waveform in a forming process according to the present invention.

FIG. 6 is a diagram illustrating a basic configuration of an image forming apparatus according to the present invention.

FIG. 7 is a diagram illustrating a fluorescent film used in the image forming apparatus of FIG. 6;

FIG. 8 is a plan view showing a configuration of a conventional electron source substrate.

FIG. 9 is a bird's-eye view showing a configuration of a conventional electron source substrate.

[Explanation of symbols]

1: substrate, 2, 3: element electrode, 4: conductive thin film, 5: electron emitting portion, 6, 7: wiring, 8: interlayer insulating layer, 9: surface coat layer, 61: electron source substrate, 62: rear Plate, 6
3: outer frame, 64: face plate substrate, 65: fluorescent film, 66: metal back, 67: face plate, 6
8: high voltage terminal, 69: vacuum envelope, 71: black conductor,
72: phosphor, 81: electron-emitting device, 91: substrate.

Continuing on the front page (72) Inventor Gakugaku Masafumi 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Masaaki Shibata 3-30-2, Shimomaruko, Ota-ku, Tokyo Canon Inc. F term (reference) 4G059 AA08 CA01 CB01 5C031 DD09 DD17 5C036 EE01 EE19 EF01 EF06 EF09 EG12 EH04 EH06

Claims (11)

[Claims] 1. An electron source substrate comprising: a plurality of electron-emitting devices each comprising a pair of device electrodes formed on a substrate via a surface coat layer and a conductive thin film having an electron-emitting portion; The amount of water contained in the coat layer is 50ppm
An electron source substrate comprising: 2. The method according to claim 1, wherein the electron-emitting device is formed by heating and baking a material for forming a conductive thin film provided on the surface coat layer so as to connect the pair of device electrodes. 2. The device according to claim 1, wherein said electron-emitting portion is provided by an energization forming process.
An electron source substrate as described in the above. 3. The electron source substrate according to claim 1, wherein carbon and / or a carbon compound is further deposited on the electron-emitting device. 4. The electron source substrate according to claim 1, wherein said substrate is a glass substrate. 5. The surface coating layer according to claim 1, wherein the surface coating layer is provided on the substrate with quartz glass melted by electro-fusion or quartz glass synthesized by mixing SiCl ₄ gas in plasma. An electron source substrate according to any one of the above. 6. The method according to claim 1, wherein the surface coat layer is formed at 400 ° C. in a vacuum.
The electron source substrate according to any one of claims 1 to 5, wherein the substrate is heated as described above. 7. The electron source substrate according to claim 1, wherein said electron-emitting device is a surface conduction electron-emitting device. 8. The electron according to claim 1, wherein device electrodes at both ends of each of said electron-emitting devices are connected to a metal wiring, and electrons are emitted according to an input signal. Source substrate. 9. The device according to claim 8, comprising a plurality of rows of electron-emitting devices in which a plurality of said electron-emitting devices are arranged in parallel, and further comprising a modulating means for modulating the input signal. Electron source substrate. 10. A pair of device electrodes of the electron-emitting device are connected to the X-direction metal wiring and the X-direction metal wiring at each intersection of the m X-direction metal wirings and the n Y-direction metal wirings electrically insulated from each other. The electron source substrate according to claim 9, wherein the electron-emitting devices are connected to a Y-direction metal wiring and the electron-emitting devices are arranged in a matrix. 11. A device for forming an image based on an input signal, wherein the device comprises at least an image forming member and the electron source substrate according to any one of claims 1 to 10. Forming equipment.