JP2000243232A - Electron emitting element, electron source substrate, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize satisfactory electron emission characteristic and high brightness by comprising a base, a pair of element electrodes formed on the base counterposed with one another, and a conductive thin film connected to the element electrodes and including a clearance portion, and specifying the maximum value of a secondary electron emissivity of the base below a predetermined value. SOLUTION: A surface conducting-type electron emission element is formed by a base 1, the element electrodes 2, 3, a conductive thin film 4 and a clearance portion 5. The base 1 is preferably made of a material having less than 2 for the maximum value of the secondary electron emissivity, when the potential difference is approximately above 300 V. To obtain superior electron emission characteristics, a particulate film formed by particulate is preferably used as the conductive thin film 4. The conductive material such as Ni, Au, PdO, Pd, Pt and the like is preferably formed into a film thickness to provide Rs (sheet resistance) of 102-107/(square) for the resistance value. The film thickness providing this resistance value is approximately within the range of 5-50 nm, and the film thickness of each material has a configuration of particulate film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron-emitting device, an electron source substrate, and an image forming apparatus such as a display device to which the electron-emitting device is applied, and more particularly, to a surface-conduction type electron-emitting device having a novel structure and using the same. The present invention relates to an electron source substrate and an image forming apparatus such as a display device as an application thereof.

[0002]

2. Description of the Related Art Conventionally, two types of electron emitting devices, a thermionic electron source and a cold cathode electron source, are known. The cold cathode electron source includes a field emission type (hereinafter abbreviated as FE type), a metal / insulating layer / metal type (hereinafter abbreviated as MIM type), and a surface conduction type electron emission element.

As an example of the FE type, see [W. P. Dyke &
W. W. Dolan, "Fielddemissio
n ", Advance in Electron Ph
ysics, 8, 89 (1956)] or [C.
A. Spindt, "Physical Proper
ties of thin-film field e
mission cathodes with mol
ybdenium cones ", J. Appl. Ph.
ys. , 47, 5248 (1976)].

As an example of the MIM type, [C. A. Mea
d, “Operation of Tunnel-Em
issue Devices ", J. Apply. P.
hys. 32, 646 (1961)].

As an example of the surface conduction electron-emitting device,
[M. I. Elinson, Radio Eng. El
electronPhys. , 10, 1290, (196
5)].

[0006] The surface conduction electron-emitting device utilizes the phenomenon that electron emission occurs when a current flows in a small-area thin film formed on a substrate in parallel with the film surface. Examples of the surface conduction electron-emitting device include a device using an SnO ₂ thin film by Elinson et al. And a device using an Au thin film [G. Dimmer, Thin Solid Fil
ms, 9,317 (1972)], In 2 O 3 / SnO
₂ Thin film [M. Hartwell and
C. G. FIG. Fonsted, IEEE Trans. ED
Conf. , 519 (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.

As a typical device configuration of these surface conduction electron-emitting devices, the above-mentioned M.D. FIG. 14 shows a device configuration of the Hartwell. In FIG. 1, reference numeral 1 denotes an insulating substrate.
Reference numeral 4 denotes a conductive thin film, which is formed of a metal oxide thin film or the like formed by sputtering in an H-shaped pattern, and a linear electron-emitting portion 5 is formed by an energization process called forming described later. Note that the element electrode interval L in the figure is 0.5 to 1 m.
m and W ′ are set at 0.1 mm.

Conventionally, in these surface conduction electron-emitting devices, before the electron emission, the electron-emitting portion 5 is generally formed by applying a current to the conductive thin film 4 by a process called forming. That is, 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 destroy, deform or alter the conductive thin film, thereby increasing the electrical conductivity. This is to form the electron-emitting portion 5 in a resistance state. In the electron emitting portion 5, a crack is generated in a part of the conductive thin film 4, and electrons are emitted from the vicinity of the crack. The surface conduction type electron-emitting device that has been subjected to the forming treatment is configured to apply a voltage to the above-described conductive thin film 4 and cause a current to flow through the device, thereby causing the above-described electron-emitting portion 5 to emit electrons.

On the other hand, as disclosed in, for example, Japanese Patent Application Laid-Open No. 7-235255, there is a case where a process called an activation process is performed on an element after forming. The activation treatment step is, when a voltage is applied to a pair of opposed device electrodes of the surface conduction electron-emitting device by this process,
This is a step in which a flowing current (hereinafter, referred to as an element current If) and a current emitted in a vacuum (hereinafter, referred to as an emission current Ie) are significantly changed.

[0010] The activation step can be performed by repeatedly applying a pulse voltage to the element in an atmosphere containing an organic substance, as in the forming process. With this process,
From the organic substance present in the atmosphere, carbon or a carbon compound is deposited on at least the electron-emitting portion of the device, and the device current If and the emission current Ie are significantly changed, so that better electron-emitting characteristics can be obtained.

An image forming apparatus can be constructed by using an electron source substrate on which a plurality of electron emitting elements as described above are formed and combining it with an image forming member made of a phosphor or the like.

[0012]

However, with the rapid progress of multimedia with the advancement of information in recent years, higher performance is required for image forming apparatuses such as displays. That is, the screen size of the display device is increased, the power consumption is reduced, the definition is increased, the image quality is increased, and the space is saved.

Therefore, in the above-described electron-emitting device, a highly efficient and stable electron-emitting characteristic can be maintained for a long time so that an image forming apparatus to which the electron-emitting device is applied can stably provide a bright display image. Technology is desired.

Here, the efficiency refers to a current ratio of the emission current Ie to the device current If of the surface conduction electron-emitting device.

That is, it is desirable that the device current If be as small as possible and the emission current Ie be as large as possible.

If high-efficiency electron emission characteristics can be stably controlled over a long period of time, for example, in an image forming apparatus using a phosphor as an image forming member, a low-power and bright high-quality image forming apparatus such as a flat TV can be realized.

In order to increase the emission current Ie, it is effective to increase the acceleration voltage (referred to as Va) for causing electrons emitted from the electron-emitting device to collide with the image forming member.

Generally, Va of several hundred V to several tens of kV is applied with the distance between the electron-emitting device and the image forming member being several mm to several cm.

However, in the conventional electron-emitting device, since a highly insulating glass substrate is used as a base, a portion where no wiring or the like for supplying a voltage to the electron-emitting device or the device is formed. That is, the exposed surface of the substrate was sometimes charged.

The mechanism of this charging is unknown in detail, but it has been found that the higher the Va, the higher the potential of the exposed surface of the substrate. When the potential of the exposed surface of the base increases due to the charging, a discharge may occur from the surface of the base toward the electron-emitting device or the wiring, possibly damaging the device.

Therefore, when driving a device by applying a large Va, the above-mentioned discharge may affect the life of the electron-emitting device, which may cause a deterioration in the quality of an image display device using the electron-emitting device. It was one.

In view of the above problems, an object of the present invention is to provide a surface conduction electron-emitting device which achieves good electron emission characteristics and high luminance for a long time, and an electron source and an image forming apparatus using the same. It is assumed that.

[0023]

Means for Solving the Problems The present invention has been made by intensive studies in order to solve the above-mentioned problems, and has the following configuration.

That is, the electron-emitting device of the present invention comprises:
An electron-emitting device having a pair of opposing element electrodes formed on a base, and a conductive thin film connected to the element electrodes and including a gap, wherein the maximum value of the secondary electron emission efficiency of the base is 2 or less. As the electron-emitting device, a surface conduction electron-emitting device can be preferably used. As the above substrate, a glass substrate can be preferably used. Further, the invention includes an electron source substrate and an image forming apparatus.

An electron source substrate according to the present invention is an electron source substrate which emits electrons in response to an input signal, wherein a plurality of the above-mentioned electron-emitting devices are arranged on a substrate, and preferably, each of the individual electron-emitting devices is provided. A plurality of rows of electron-emitting devices having both ends connected to wirings, and further comprising a modulation means for modulating an input signal. More preferably, the substrate has m X-directional metal wires and n Y wires electrically insulated from each other.
At each intersection with the directional metal wiring, a pair of device electrodes of the electron-emitting device are connected to the X-direction metal wiring and the Y-direction metal wiring, respectively, and the electron-emitting devices are arranged in a matrix. is there.

An image forming apparatus according to the present invention is an apparatus for forming an image based on an input signal, and is characterized by comprising at least an image forming member and the above-mentioned electron source.

According to the surface conduction electron-emitting device of the present invention, since the base is made of a material having a low secondary electron emission efficiency, creeping discharge is hardly generated on the surface thereof.
Even when a high Va is applied, deterioration of the device due to discharge or the like can be suppressed, and as a result, an electron-emitting device that can maintain stable electron-emitting characteristics for a long time can be realized.

Further, according to the image forming apparatus of the present invention, a stable and good image can be formed for a long time.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described. First, the basic configuration of the surface conduction electron-emitting device according to the present invention will be described.

FIGS. 1A and 1B are a plan view and a sectional view, respectively, showing the structure of a basic surface conduction electron-emitting device according to the present invention. The basic configuration of the device according to the present invention will be described with reference to FIG.

In FIG. 1, 1 is a substrate, 2 and 3 are device electrodes, 4 is a conductive thin film, and 5 is a gap. As the substrate 1, a material having a maximum secondary electron emission efficiency of 2 or less can be used. In particular, a glass substrate is relatively inexpensive and easy to handle when forming a vacuum envelope as described later. As described later, when the secondary electron emission efficiency exceeds 2, when a potential difference occurs between the surface of the base and the electron-emitting device, creeping discharge is likely to occur.

The secondary electron emission efficiency referred to here is a value when the potential difference is about 300 V or more.

The material of the opposing device electrodes 2 and 3 may be any material as long as it has conductivity. For example, Ni, Cr, Au, Mo, W, Pt,
Metals or alloys such as Ti, Al, Cu, Pd and Pd;
A printed conductor composed of a metal such as Ag, Au, RuO ₂ , Pd-Ag or a metal oxide and glass; In ₂ O ₃ −
Examples include a transparent conductor such as SnO ₂ and a semiconductor material such as polysilicon.

The element electrode interval L, the element electrode length W, the shape of the conductive thin film 4 and the like are appropriately designed depending on the application form of the element, and for example, in a display device such as a television to be described later, it corresponds to the screen size. In particular, high-definition televisions require a small pixel size and high definition. Therefore, in order to obtain a sufficient luminance even when the size of the electron-emitting device is limited, it is designed so that a sufficient emission current is obtained.

The element electrode interval L is from several tens nm to several hundred μm.
Yes, photolithography technology that is the basis of the method for manufacturing device electrodes, that is, the performance and etching method of the exposure machine,
And the voltage applied between the device electrodes,
Preferably, it is from several μm to several tens μm.

The element electrode length W and the film thickness d of the element electrodes 2 and 3 are appropriately designed in consideration of the resistance of the electrodes, the connection with the XY wiring, and the arrangement of a large number of electron sources.
Usually, the length W of the device electrode is several μm to several hundred μm, and the film thickness d of the device electrodes 2 and 3 is several nm to several μm.

As the conductive thin film 4, it is preferable to use a fine particle film composed of fine particles in order to obtain good electron emission characteristics. The film thickness is appropriately set in consideration of the step coverage for the device electrodes 2 and 3, the resistance value between the device electrodes 2 and 3, a forming condition described later, and the like.

Examples of materials satisfying the above conditions include Ni,
It is preferable to use a conductive material such as Au, PdO, Pd, and Pt formed with a film thickness having an Rs (sheet resistance) of 10 ² to 10 ⁷ / □. Note that Rs is a resistance R measured in the length direction of a thin film having a thickness t, a width w, and a length l, and a value that appears when R = Rs (l / w).
If the resistivity is ρ, then Rs = ρ / t. The film thickness showing the above resistance value is in the range of about 5 nm to 50 nm,
Within this thickness range, the thin film of each material has the form of a fine particle film.

The fine particle film described here is a film in which a plurality of fine particles are aggregated, and has a fine structure in a state in which the fine particles are individually dispersed and arranged, or in a state in which the fine particles are adjacent to each other or overlapped (some fine particles are formed). To form an island-like structure as a whole).

The particle size of the fine particles is in the range of several hundred pm to several hundred nm, preferably in the range of 1 nm to 20 nm.

Now, among the materials exemplified above, Pd
O can be easily formed into a thin film by baking an organic Pd compound in the air, has relatively low electric conductivity because of being a semiconductor, has a wide process margin of film thickness for obtaining the resistance value Rs in the above range, and has a gap portion. It is a suitable material because it can be easily reduced to metal Pd later, so that the film resistance can be reduced. However, the effects of the present invention are not limited to PdO, and are not limited to the materials exemplified above.

The gap portion 5 is a high resistance portion such as a crack formed in a part of the conductive thin film 4, and is formed by a deposit mainly composed of carbon through an activation step described later. , A structure having a narrower gap. When a voltage is applied to the gap 5, electrons are emitted, a part of which is emitted as an element current If, and a part is emitted into a vacuum, which becomes an emission current Ie.

Various methods are conceivable as a method of manufacturing the electron-emitting device having the gap 5, and an example is shown in FIG.

The manufacturing method will be described below in order with reference to FIGS. 1) After sufficiently washing the base 1 with a detergent, pure water and an organic solvent, an element electrode material is deposited by a vacuum evaporation method, a sputtering method or the like, and then the element electrodes 2 and 3 are formed by a photolithography technique (FIG. 2 ( a)).

2) An organic metal solution is applied between the element electrode 2 and the element electrode 3 provided on the base 1 and dried to form an organic metal film. The organic metal solution is a solution of an organic metal compound containing a metal such as Pd, Ni, Au, or Pt as a main element. Thereafter, the organic metal film is heated and baked, and is patterned by lift-off, etching, or the like to form a conductive thin film 4 (FIG. 2).
(B)). Here, the method of applying the organic metal solution has been described, but the method of forming the conductive thin film 4 is not limited to this, and the vacuum deposition method, the sputtering method, the CVD method, the dispersion coating method, the dipping method, the spinner method And may be formed by an inkjet method or the like.

3) Subsequently, an energizing process called forming is performed by applying a pulsed voltage or a rising voltage between the element electrodes 2 and 3 using a power supply (not shown).
A gap portion 5 having a changed structure is formed at a portion of the conductive thin film 4 (FIG. 2C). By this energization treatment, the conductive thin film 4
Electrons are emitted from the vicinity of the gap 5 formed in the substrate.

The electrical processing after the forming processing is performed in the measurement and evaluation apparatus shown in FIG. The measurement evaluation device will be described below. FIG. 3 is a schematic configuration diagram of a measurement evaluation device for measuring the electron emission characteristics of the device having the configuration shown in FIG. In FIG. 3, reference numeral 1 denotes a base, 2 and 3 denote device electrodes, 4 denotes a conductive thin film, and 5 denotes a gap. Reference numeral 31 denotes a power supply for applying a device voltage Vf to the device, reference numeral 30 denotes an ammeter for measuring a device current If flowing through the conductive thin film 4 between the device electrodes 2 and 3, and reference numeral 34 denotes emission from an electron emission portion of the device. An anode electrode 33 for capturing the emission current Ie
Is a high-voltage power supply for applying a voltage to the anode electrode 34,
Reference numeral 32 denotes an ammeter for measuring an emission current Ie emitted from the electron emission portion of the device.

In measuring the device current If and the emission current Ie of the electron-emitting device, the device electrodes 2 and 3 are connected to a power source 31 and an ammeter 30, and a power source 3 is provided above the electron-emitting device.
An anode electrode 34 connecting the 3 and the ammeter 32 is arranged. Further, the electron-emitting device and the anode electrode 34 are installed in a vacuum device, and the vacuum device is provided with equipment necessary for a vacuum device such as an exhaust pump (not shown) and a vacuum gauge. Can be measured and evaluated. The exhaust pump includes a high-vacuum system such as a magnetic levitation turbo pump and a dry pump that does not use oil, and an ultra-high vacuum system including an ion pump. The entire vacuum device and the electron-emitting device can be heated by a heater (not shown).

The voltage of the anode electrode is set to 5 kV to 10 kV.
kV, the distance H between the anode electrode and the electron-emitting device is 2 mm
It was measured in a range of ８8 mm.

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. 4A shows a voltage waveform in a case where a pulse having a pulse peak value of a constant voltage is applied.

In FIG. 4 (a), T1 and T2 are the pulse width and pulse interval of the voltage waveform, and T1 is 1 second to 1 second.
0 msec, T2 is set to 10 μsec to 100 msec, and the peak value of the triangular wave (peak voltage at the time of forming) is appropriately selected.

Next, FIG. 4B shows a voltage waveform when a voltage pulse is applied while increasing the pulse peak value. In FIG. 4B, T1 and T2 are the pulse width and pulse interval of the voltage waveform, and T1 is 1 sec to 10 ms.
ec and T2 are set to 10 μsec to 100 msec, and the peak value (peak voltage at the time of forming) of the triangular wave is increased by, for example, about 0.1 V steps.

The forming process is terminated when the conductive thin film 2 is locally destroyed during the forming pulse.
A voltage that does not deform, for example, a pulse voltage of about 0.1 V is inserted, and the element current is measured to obtain a resistance value.
When the resistance was 1 MΩ or more, the forming was terminated.

When forming the gap described above, the forming process is performed by applying a triangular wave pulse between the electrodes of the device, but the waveform applied between the electrodes of the device is not limited to the triangular wave. A desired waveform such as a rectangular wave may be used, and the peak value, pulse width, pulse interval, and the like are not limited to the above-described values. Select an appropriate value according to.

4) Next, an activation process is performed on the element for which the forming has been completed. The activation process is performed in an atmosphere containing an organic substance. This atmosphere uses an organic substance remaining in the atmosphere when the inside of the vacuum vessel is evacuated using, for example, an oil diffusion pump or a rotary pump. In addition, it can be obtained by introducing an appropriate organic substance into a vacuum once sufficiently evacuated by an ion pump or the like. The preferable pressure of the organic substance at this time differs depending on the above-described application form, the shape of the vacuum vessel, the type of the organic substance, and the like, and is appropriately set according to the case.

Suitable organic substances include alkanes, alkenes, aliphatic hydrocarbons of alkynes, aromatic hydrocarbons, alcohols, aldehydes, ketones, amines, nitriles, phenols, carboxylic acids, sulfonic acids and the like. Organic acids and the like, specifically, methane, ethane, propane such as saturated hydrocarbon represented by C _n H _{2n +2} , ethylene, propylene represented by a composition formula such as C _n H _2n Unsaturated hydrocarbons, 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 is deposited on the element from the organic substance existing in the atmosphere, and the element current If and the emission current Ie change remarkably.

The termination of the activation step is appropriately determined while measuring the device current If and / or the emission current Ie. The pulse width, pulse interval, pulse crest value, and the like can be set as appropriate.

5) The electron-emitting device thus manufactured is preferably subjected to a stabilization step. This step is a step of exhausting the organic substance in the vacuum container. The pressure in the vacuum vessel is preferably 1 to 3 × 10 ⁻⁷ Torr or less, and more preferably 1 to 3 × 10 ⁻⁷ Torr.
It is particularly preferably at most 10 × 10 ⁻⁸ Torr. When the inside of the vacuum vessel is evacuated, it is preferable to heat the entire vacuum vessel so that the organic substance molecules adsorbed on the inner wall of the vacuum vessel and the electron-emitting device can be easily evacuated. The heating conditions at this time are 80 to
It is desirable to carry out the treatment at 350 ° C., preferably 200 ° C. or more for as long as possible. However, the condition is not particularly limited, and the treatment is carried out under conditions appropriately selected according to various conditions such as the size and shape of the vacuum vessel and the configuration of the electron-emitting device. .

It is preferable that the atmosphere at the time of driving after the stabilization process is performed is the same as the atmosphere at the end of the stabilization process, but the present invention is not limited to this. 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 basic characteristics of the electron-emitting device manufactured by the above-described manufacturing method to which the present invention can be applied will be described with reference to FIGS. FIG. 5 shows a typical example of the emission current Ie, the device current If, and the device voltage Vf measured by the measurement evaluation device shown in FIG. In addition, FIG.
Since the emission current Ie is significantly smaller than the device current If, the emission current Ie is shown in an arbitrary unit, and each is a linear scale. As is clear from FIG. 5, the electron-emitting device has three properties with respect to the emission current Ie.

First, when an element voltage higher than a certain voltage (called a threshold voltage, Vth in FIG. 5) is applied to the present element, the emission current Ie sharply increases, while the threshold voltage Vt
Below h, the emission current Ie is hardly detected. That is, a clear threshold voltage Vth with respect to the emission current Ie
Is a non-linear element having

Second, since the emission current Ie depends on the device voltage Vf, the emission current Ie can be controlled by the device voltage Vf.

Third, the amount of charge discharged by the anode electrode 34 depends on the time during which the device voltage Vf is applied. That is, the amount of charge captured by the anode electrode 34 can be controlled by the time during which the device voltage Vf is applied.

When the characteristics of the surface conduction electron-emitting device described above are used, the electron emission characteristics can be easily controlled according to the input signal. Further, since the electron-emitting device according to the present invention has stable and high-luminance electron emission characteristics for a long time, application to various fields can be expected.

An application example of the electron-emitting device to which the present invention can be applied will be described below. By arranging a plurality of surface conduction electron-emitting devices according to the present invention on a substrate, for example, an electron source or an image forming apparatus can be configured.

For the arrangement of the elements on the substrate, for example,
A large number of electron-emitting devices are arranged in parallel, and both ends of each element are connected by wiring. A large number of electron-emitting device rows are arranged (referred to as a row direction). ), A control electrode (called a grid) installed in the space above the electron source to control and drive the electrons (called a ladder type), and n There is an array configuration in which the Y-directional wiring is disposed via an interlayer insulating layer, and the X-directional wiring and the Y-directional wiring are connected to a pair of device electrodes of the surface conduction electron-emitting device, respectively. Hereinafter, this is referred to as a simple matrix arrangement.

Next, the simple matrix arrangement will be described in detail. According to the characteristics of the above-mentioned three basic characteristics of the surface conduction electron-emitting device according to the present invention, the electrons emitted from the surface conduction electron-emitting device are above the threshold voltage.
It can be controlled by the peak value and the width of the pulse voltage applied between the opposing element electrodes. On the other hand, when the voltage is equal to or lower than the threshold voltage, it is hardly emitted. According to this characteristic, even when a large number of electron-emitting devices are arranged, if the pulse-like voltage is appropriately applied to each of the devices, a surface conduction electron-emitting device is selected in accordance with an input signal. The amount of electron emission can be controlled.

Hereinafter, the configuration of the electron source substrate formed based on this principle will be described with reference to FIG. Wiring 62, 6
Reference numeral 3 is for supplying power to a plurality of electron-emitting devices. DX lines DX1, DX2,... DX
DY1, DY2,... DYn
The material, the film thickness, the wiring width, and the like are designed so that substantially equal voltages are supplied to a large number of electron-emitting devices. An interlayer insulating layer 64 is provided between the m X-directional wirings 63 and the n Y-directional wirings 62 and electrically separated to form a matrix wiring (m, n).
Are both positive integers).

The shape, material, film thickness, and manufacturing method of the interlayer insulating layer 64 can be appropriately set so as to withstand the potential difference at the intersection of the wiring 62 and the wiring 63. However, like the wiring, a material that can be formed by a printing method is preferable. A thick glass layer obtained by printing a glass paste is used.

In the configuration shown in FIG. 6, that is, in the configuration of the matrix arrangement, a scanning signal (not shown) for applying a scanning signal for selecting a row of the electron-emitting devices arranged in the X direction is applied to the X-directional wiring 63. The Y-direction wiring 62 is connected to a modulation signal generating means (not shown) for modulating each column of the electron-emitting devices arranged in the Y-direction in accordance with 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 device are controlled and driven by a control electrode arranged above,
The present invention is not particularly limited by these arrangements.

Next, an image forming apparatus for display and the like using the electron source substrate manufactured as described above will be described with reference to FIGS. FIG. 7 is a basic configuration diagram of the image forming apparatus, and FIG. 8 is a fluorescent film.

In FIG. 7, reference numeral 71 denotes an electron source substrate on which a plurality of electron-emitting devices are arranged; 72, a rear plate on which the electron source substrate 71 is fixed; 77, a fluorescent film 75 on the inner surface of a glass substrate 74;
And a face plate on which a metal back 76 and the like are formed, and 73 is a support frame. The rear plate 72, the support frame 73, and the face plate 77 are sealed by applying a frit glass or the like and heating and firing in air or nitrogen to form an envelope 79. Here, it is preferable that the frit glass be used in accordance with the coefficient of thermal expansion of the substrate because peeling, deformation, cracking, and the like of the substrate hardly occur.

The envelope 79 includes the face plate 77, the support frame 73, and the rear plate 72 as described above. However, since the rear plate 72 is provided mainly for the purpose of reinforcing the strength of the substrate 71, If the substrate itself has sufficient strength, the separate rear plate 72 is unnecessary, and
1, a support frame 73 is directly sealed, and a face plate 77,
The envelope 79 may be constituted by the support frame 73 and the substrate 71.

On the other hand, by providing a support (not shown) called a spacer between the face plate 77 and the rear plate 72, an envelope 79 having sufficient strength against atmospheric pressure can be formed. .

FIG. 8 shows a fluorescent film. The fluorescent film 75 is composed of only a phosphor in the case of a monochrome, but is composed of a black conductive material 81 called a black stripe or a black matrix and a phosphor 82 depending on the arrangement of the phosphor 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 between the phosphors 82 of the three primary color phosphors necessary for the color display black so that the color mixture and the like become inconspicuous. In suppressing a decrease in contrast due to reflection of external light. As a material of the black conductive material 81 such as a black stripe, not only a material mainly containing graphite, which is often used, but also a conductive material,
The material is not limited to this as long as the material transmits and reflects less light.

The method of applying the phosphor on the glass substrate 74 is not limited to monochrome or color, but a precipitation method, a printing method, or the like is used.

A metal back 76 is usually provided on the inner side of the fluorescent film 75. The purpose of the metal back 76 is
Improving the brightness by mirror-reflecting the light toward the inner surface side of the light emitted from the phosphor 82 toward the face plate 77 side, acting as an electrode for applying an electron beam accelerating voltage, This is to protect the phosphor 82 from damage caused by the collision of the generated negative ions. After the fluorescent film 75 is formed, the metal back 76 is subjected to a smoothing treatment of the inner surface of the fluorescent film 75 (usually called filming).
And then depositing Al using vacuum evaporation or the like.

The face plate 77 further includes a fluorescent film 7.
A transparent electrode (not shown) may be provided on the outer surface side of the fluorescent film 75 in order to increase the conductivity of the fluorescent film 75.

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 79 is connected to an exhaust pipe (not shown) to
After the degree of vacuum is set to about × 10 ⁻⁷ Torr, sealing is performed. Further, a getter process may be performed in order to maintain the degree of vacuum after sealing the envelope 79. This is because the getter disposed at a predetermined position (not shown) in the envelope 79 is heated by a heating method such as resistance heating or high-frequency heating immediately before or after sealing the envelope 79. ,
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 according to the present invention completed as described above, each electron-emitting device is provided with an outer terminal Dox.
1 to Doxm and Doy1 to Doyn, a voltage is applied to emit electrons, and the high voltage terminal 78
Through, metal back 76 or transparent electrode (not shown)
A high voltage of several kV or more is applied to accelerate the electron beam, collide with the fluorescent film 75, and excite and emit light to display an image.

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 device.

[0087]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples. (Embodiment 1) The basic structure of a surface conduction electron-emitting device according to this embodiment is the same as the plan view and cross-sectional view of FIGS.

The method for manufacturing the surface conduction electron-emitting device according to this embodiment is basically the same as that shown in FIG. Hereinafter, a basic configuration and a manufacturing method of the element according to the present embodiment will be described with reference to FIGS.

Hereinafter, the manufacturing method will be described in order with reference to FIGS. Step-a First, a cleaned V ₂ O ₅ —P ₂ O ₅ —Cs ₂ O glass (secondary electron emission efficiency δmax = 1.6, Vmax = 3
50V) A pattern to be a gap L between the device electrodes 2 and 3 and a desired device electrode is formed on the substrate 1 by a photoresist (RD).
-2000N-41 manufactured by Hitachi Chemical Co., Ltd.), and 5 nm thick Ti and 100 nm thick Ni were sequentially deposited by electron beam evaporation. The photoresist pattern was dissolved in an organic solvent, and the Ni / Ti deposited film was lifted off to form device electrodes 2 and 3 having a device electrode interval L of 3 μm and a device electrode width W of 300 μm.

Step-b: A Cr film having a thickness of 100 nm is deposited by vacuum evaporation, patterned so as to have an opening corresponding to the shape of the conductive thin film 4 described later, and then an organic palladium compound solution (ccp4230 Okuno Pharmaceutical Co., Ltd.) Co., Ltd.) was spin-coated with a spinner and baked at 300 ° C. for 12 minutes. The conductive thin film 4 formed of fine particles of Pd as the main element thus formed had a thickness of 10 nm and a sheet resistance Rs of 2 × 10 ⁴ Ω / □. Note that the fine particle film described here is a film in which a plurality of fine particles are aggregated as described above.

Step-c The Cr film and the baked conductive thin film 4 were etched with an acid etchant to form a conductive thin film 4 having a desired pattern. Through the above steps, the device electrodes 2 and 2
3 and a conductive thin film 4 were formed.

Step-d Next, the substrate 1 was set in the measurement / evaluation apparatus shown in FIG. 3, evacuated by a vacuum pump, and after reaching a degree of vacuum of 1 × 10 ⁻⁸ Torr, an element voltage Vf was applied to the element. A voltage was applied between the device electrodes 2 and 3 by a power supply 31 for application, and a forming process was performed. The voltage waveform of the forming process is that shown in FIG.

In FIG. 4B, T1 and T2 are the pulse width and pulse interval of the voltage waveform. In this embodiment, T1 is 1 m.
sec, T2 was set to 10 msec, and the peak value of the rectangular wave was stepped up in steps of 0.1 V to perform a forming process. During the forming process, a resistance measuring pulse was simultaneously inserted between the forming pulses at a voltage of 0.1 V to measure the resistance. The forming process was terminated when the value measured by the resistance measurement pulse became about 1 MΩ or more, and at the same time, the application of the voltage to the element was terminated.

Step-e Subsequently, in order to perform the activation step, benzonitrile was introduced into the vacuum apparatus through a slow leak valve.
0 × 10 ⁻⁶ Torr was maintained. Next, the element subjected to the forming treatment was activated at a peak value of 14 V with the waveform shown in FIG. That is, a pulse voltage was applied between the device electrodes while measuring the device current If in the measurement and evaluation device. Since the If value was substantially saturated in about 30 minutes, the energization was stopped, the slow leak valve was closed, and the activation process was terminated.

Step-f Subsequently, a stabilizing step was performed. While the vacuum device and the electron-emitting device were heated by the heater and maintained at about 250 ° C., the evacuation of the vacuum device was continued. After 20 hours, stopped heating by the heater, the pressure in the vacuum chamber was returned to room temperature was reached about 5 × 10 ^{-1 0} Torr.

Subsequently, the electron emission characteristics were measured.
The distance H between the anode electrode 34 and the electron-emitting device is 4 mm
10 kV to the anode electrode 34 by the high voltage power supply 33.
Was applied. In this state, a rectangular pulse voltage having a peak value of 14 V is applied between the device electrodes 2 and 3 using the power supply 31, and the current of the device of the present example and the device of the comparative example are measured by the ammeter 30 and the ammeter 32. Current If and emission current I
e were measured respectively.

During the measurement, when the potential of the exposed surface of the substrate 1 was measured with a surface voltmeter, a potential rise of 300 V or more was observed in several minutes.

The electron emission characteristics of the device of this example are as follows: device current If = 4.0 mA, emission current Ie = 25.3 μA, electron emission efficiency η (= Ie / If) = 0.63%. Although driving was continued, discharge did not occur in particular, and good characteristics were maintained.

Comparative Example 1 In this comparative example, quartz glass (secondary electron emission efficiency δmax = 2.1, Vm
ax = 400 V) Except for using the substrate, the configuration is the same as that of Example 1, and the electron-emitting device is manufactured by the same manufacturing method. The electron emission characteristics of the device of this comparative example were measured in the same manner as in Example 1.

The distance H between the anode 34 and the electron-emitting device was 4 mm, and the anode 3
4 was given a potential of 10 kV. In this state, a rectangular pulse voltage having a peak value of 14 V is applied between the element electrodes 2 and 3 using the power supply 31, and the ammeter 30 and the ammeter 32
The device current If and the emission current Ie of the device of this example and the device of the comparative example were measured.

During the measurement, when the potential of the exposed surface of the substrate 1 was measured with a surface voltmeter, a potential rise of 300 V or more was observed in several minutes.

The electron emission characteristics of the device of this example were as follows: device current If = 4.0 mA, emission current Ie = 24.0 μA, and electron emission efficiency η (= Ie / If) = 0.60%. Several minutes after the start of driving, discharge occurred, and the device characteristics were greatly deteriorated.

Embodiment 2 This embodiment is an example of an image forming apparatus in which a large number of surface conduction electron-emitting devices are arranged in a simple matrix. FIG. 10 shows a part of the electron source substrate. FIG. 11 is a cross-sectional view taken along the line AA ′ in the figure. However, FIG. 10, FIG.
The same symbol in 1 indicates the same item. Here, 1 is a substrate, 63 is an X-direction wiring (also referred to as an upper wiring) corresponding to DXm in FIG. 6, 62 is a Y-direction wiring (also referred to as a lower wiring) corresponding to DYn in FIG. , 3 are device electrodes, 5 is a gap, and 64 is an interlayer insulating layer.

Next, the manufacturing method will be described specifically with reference to FIGS. Step-a Cleaned V ₂ O ₅ —P ₂ O ₅ —Cs ₂ O glass (secondary electron emission efficiency δmax = 1.6, Vmax = 350 V)
Ti having a thickness of 5 nm and Pt having a thickness of 50 nm are sequentially deposited on the substrate 1 by a sputtering method. Then, the device electrodes 2,
3 is formed of photoresist, and Pt other than the pattern of the device electrodes 2 and 3 is formed by dry etching.
The / Ti deposited layer is removed, and finally the photoresist pattern is removed to form device electrodes 2 and 3 (FIG. 12A).

Step-b On the substrate 1 on which the device electrodes 2 and 3 have been formed, a pattern of the wiring 62 is formed by using an Ag paste by screen printing, dried, baked at 500 ° C., and made of a desired Ag material. A wiring 62 having a shape is formed (FIG. 12B).

Step-c Next, a pattern of the interlayer insulating layer 64 is formed by screen printing using a glass paste.
Baking. In order to obtain sufficient insulating properties, printing, drying, and firing of the glass paste are repeated again to form an interlayer insulating layer 64 of a desired shape made of glass (FIG. 12C).

Step-d The pattern of the upper wiring 63 is formed by screen printing using an Ag paste so as to intersect with the lower wiring 62 at the portion where the interlayer insulating layer 64 is formed.
Baking is performed at 0 ° C. to form an upper wiring 63 having a desired shape made of Ag (FIG. 13A). Through the above steps, a substrate in which the element electrodes 2 and 3 are connected in a matrix by the wirings 62 and 63 can be formed.

Step-e Next, the conductive thin film 4 is formed so as to extend between the gaps between the device electrodes 2 and 3. The conductive thin film 4 is formed 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. Thus, it is composed of fine particles mainly composed of PdO, and has a film thickness of about 1
A conductive thin film 4 having a thickness of 0 nm is obtained (FIG. 13B). Through the above steps a to e, the lower wiring 62, the interlayer insulating layer 64, the upper wiring 63, the device electrodes 2, 3 and the conductive thin film 4 are formed on the base 1.
Was formed to produce an electron source substrate.

Hereinafter, using the electron source substrate of this embodiment,
An example in which the image forming apparatus is configured will be described with reference to FIGS. After fixing the electron source substrate 71 manufactured as described above on the rear plate 72, the electron source substrate 71
A face plate 77 (formed by forming a fluorescent film 75 and a metal back 76 on the inner surface of a glass substrate 74) is disposed above a support frame 73, and the face plate 77
7. A frit glass was applied to the joint between the support frame 73 and the rear plate 72, and was baked at 400 ° C. for 30 minutes in the air to seal.

The fluorescent film 75 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. The fluorescent film 75 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 onto the glass substrate 74.

Further, a metal back 76 is usually provided on the inner surface side of the fluorescent film 75. The metal back is the fluorescent film 75
After the fabrication, the inner surface of the fluorescent film 75 was subjected to a smoothing treatment (usually called filming), and then the Al film was fabricated by vacuum evaporation.

The face plate 77 is further provided with a fluorescent film 7.
In some cases, a transparent electrode (not shown) is provided on the outer surface of the fluorescent film 75 in order to increase the conductivity of electricity 5 and the like. However, in this embodiment, a sufficient conductivity was obtained only with the metal back. Omitted.

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

The atmosphere in the glass container completed as described above is exhausted 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 shown in FIG.
Is the same as

In this embodiment, T1 is 1 msec, and T2 is 1
The process was performed at 0 msec in a vacuum atmosphere of about 1 × 10 ⁻⁵ Torr.

Thereafter, the entire glass container was heated at 200 ° C. for 2 hours while evacuating with a vacuum pump. At this time, the conductive thin film 4 containing PdO as a main component was thermally reduced to become a film containing Pd as a main component.

Next, the exhaust was continued until the pressure in the panel reached the level of 10 ^-8 Torr, and then the organic substance was injected 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 gap 5 was formed by performing the forming and the activation processing (FIG. 13C).

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, gettering was performed by a high-frequency heating method.

In the image display device of the present invention completed as described above, each of the electron-emitting devices has an external terminal Dox1.
A scanning signal and a modulation signal are applied from a signal generating means (not shown) through Doxm, Doy1 to Doyn, respectively, to emit electrons, and a metal back 76 or a transparent electrode (not shown) through a high voltage terminal 78.
, A high voltage of 10 kV was applied to accelerate the electron beam, collided with the fluorescent film 75, and excited and emitted light to display an image.

The image display device of this example was able to stably display a good image with sufficient luminance for a long time as a television.

[0122]

As described above, according to the present invention, since a material having a secondary electron emission coefficient as small as 2 or less is used as a substrate, even if a high Va is applied, there is no influence of discharge or the like, and a stable An electron-emitting device capable of extracting an electron-emitting current for a long time can be provided.

Further, in an electron source substrate that emits electrons in response to an input signal, a plurality of electron-emitting devices of the present invention are arranged on the substrate to constitute an electron source. Has a plurality of rows of electron-emitting devices whose both ends are connected to a wiring, and further has a modulation method for modulating an input signal, or m substrates electrically insulated from each other on a substrate. At each intersection of the X-direction wiring and the n Y-direction wirings, a pair of device electrodes of the electron-emitting device are connected to the X-direction metal wiring and the Y-direction metal wiring, respectively.
By using an electron source substrate in which the electron-emitting devices are arranged in a matrix, it is possible to provide an electron source in which each electron-emitting device can maintain good electron-emitting characteristics for a long time.

In the image forming apparatus of the present invention,
An image forming apparatus comprising an image forming member and the electron source substrate of the present invention, and forms an image based on an input signal, so that the stability of electron emission characteristics and the life can be improved. For example, an image forming apparatus using a phosphor as an image forming member In, a high-quality image forming apparatus can be realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a basic surface conduction electron-emitting device according to the present invention.

FIG. 2 is a view for explaining a basic method of manufacturing a surface conduction electron-emitting device according to the present invention.

FIG. 3 is a diagram of a measurement and evaluation apparatus used for evaluating characteristics of the surface conduction electron-emitting device according to the present invention.

FIG. 4 is a diagram showing an example of a voltage waveform in a forming process according to the present invention.

FIG. 5 is a diagram showing a typical example of the relationship among the emission current, the device current, and the device voltage of the surface conduction electron-emitting device according to the present invention.

FIG. 6 is a diagram showing a configuration of an electron source substrate according to the present invention.

FIG. 7 is a diagram illustrating a basic configuration of an image forming apparatus according to the present invention.

FIG. 8 is a diagram illustrating a fluorescent film used in the image forming apparatus of FIG. 7;

FIG. 9 shows an activation pulse shape suitable for the present invention.

FIG. 10 is a diagram illustrating a part of a configuration of an electron source according to a second embodiment of the present invention.

11 is a sectional view taken along the line AA 'of FIG.

FIG. 12 is a diagram for explaining a manufacturing process of the electron source according to the second embodiment of the present invention.

FIG. 13 is a view illustrating a manufacturing process of the electron source according to the second embodiment of the present invention.

FIG. 14 is a diagram showing a configuration of a conventional surface conduction electron-emitting device.

[Explanation of symbols]

1: Base, 2, 3: element electrode, 4: conductive thin film, 5: gap, 30: ammeter for measuring element current If flowing through conductive thin film between element electrodes 2, 3; 31: electron A power supply for applying an element voltage Vf to the emission element; an ammeter for measuring an emission current Ie emitted from an electron emission portion of the element; a high-voltage power supply for applying a voltage to an anode electrode; 34: anode electrode, 62: Y direction wiring, 63: X direction wiring, 64: interlayer insulating layer, 71: electron source substrate, 72: rear plate, 73: support frame, 74: face plate glass substrate, 75: fluorescent light Film: 76: metal back, 77: face plate, 78: high voltage terminal, 79: envelope, 81: black conductive material, 82: phosphor.

Continuing on the front page (72) Inventor Kazuya Miyazaki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Tomoko Maruyama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. F term (reference) 5C036 EE01 EE09 EF01 EF06 EF09 EG02 EG12 EH21

Claims (7)

[Claims] An electron-emitting device comprising: a base; a pair of opposing element electrodes formed on the base; and a conductive thin film connected to the element electrode and including a gap. An electron-emitting device having a maximum secondary electron emission efficiency of 2 or less. 2. The electron-emitting device according to claim 1, wherein the electron-emitting device is a surface conduction electron-emitting device. 3. The electron-emitting device according to claim 1, wherein the substrate is a glass substrate. 4. An electron source substrate for emitting electrons according to an input signal, wherein a plurality of the electron-emitting devices according to claim 1 are arranged on a substrate. Source board. 5. The method according to claim 1, further comprising: arranging a plurality of the electron-emitting devices in parallel, having a plurality of rows of the electron-emitting devices each having both ends connected to a metal wiring, and further comprising a means for modulating the input signal. The electron source substrate according to claim 4, wherein 6. A pair of element electrodes of said electron-emitting device are connected to said X-direction metal wiring and said X-direction metal wiring at respective intersections of m X-direction metal wirings and n Y-direction metal wirings electrically insulated from each other. 6. The electron source substrate according to claim 5, wherein the electron emission devices are connected to a Y-direction metal wiring, and the electron-emitting devices are arranged in a matrix. 7. An apparatus for forming an image based on an input signal, wherein the apparatus comprises at least an image forming member and the electron source substrate according to any one of claims 4 to 6. Forming equipment.