JP2002352699A - Electron emission element, electron source and image formation device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron emission element capable of preventing discharge breakdown occurring in an electron emission part of the electron emission element due to an overvoltage and improved in reliability of an electron emission characteristic and durability. SOLUTION: This electron emission element comprises a pair of facing element electrodes formed on a substrate, and a first conductive thin film having the electron emission part formed between the element electrodes. The electron emission element is so composed that the first conductive thin film between the element electrodes is divided into at least plural parts, and the plurally divided first conductive thin films are connected to one another by a second conductive film constituting the electron emission part.

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, and more particularly, to a surface-conduction electron-emitting device, an electron source having a plurality of such devices, and a display device using the electron source.

[0002]

2. Description of the Related Art A surface conduction electron-emitting device utilizes a phenomenon in which an electron is emitted by passing a current through a conductive thin film formed on an insulating substrate in parallel with the film surface.

As a typical configuration example of a surface conduction electron-emitting device, as shown in FIG. 15, a metal oxide or the like that connects between a pair of device electrodes 4 and 5 provided on an insulating substrate 1 is used. An example in which the electron emitting portion 8 is formed on the conductive thin film 3 by an energization process called forming in advance. Forming is usually performed by applying a voltage to both ends of the conductive thin film 3 and energizing the conductive thin film 3. The conductive thin film 3 is locally destroyed, deformed or deteriorated to change its structure, and the state of an electrically high resistance state is reduced. This is a process for forming the electron emission section 8. The electron emission is performed from the vicinity of a crack generated in the electron emitting portion 8 by applying a voltage to the conductive thin film 3 on which the electron emitting portion 8 is formed and causing a current to flow.

The above-mentioned surface conduction electron-emitting device has an advantage that it can be formed in a large number over a large area since it has a simple structure and is relatively easy to manufacture. Therefore, various applications for utilizing this feature are being studied. For example, it can be used for an image forming apparatus such as a charged beam source and a display device.

Conventionally, as an example of arranging a large number of surface conduction electron-emitting devices, a surface conduction electron-emitting device is arranged in parallel, and both ends (both device electrodes) of each surface conduction electron-emitting device are wired. (Also referred to as a common wiring). An electron source in which rows connected by a plurality of rows (also referred to as a common wiring) are arranged in a large number of rows (also referred to as a trapezoidal arrangement) (JP-A-64-31332, JP-A-1-2302)
No. 83749, JP-A-1-257552).

[0006]

However, when driving the surface conduction electron-emitting device having the above-described structure, a driving voltage is applied between the device electrodes 4 and 5, but the driving voltage is applied due to external noise or the like. Overvoltage may be applied due to fluctuation of the voltage.

[0007] Due to this overvoltage, excessive electron emission occurs in the electron emitting portion 8, and further, as shown in FIG. 16, a discharge is generated in the conductive thin film 3 and the element is sometimes destroyed.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, that is, to prevent discharge breakdown occurring in an electron-emitting portion of an electron-emitting device due to an overvoltage, to improve the reliability of the electron-emitting characteristics, and to use a larger overvoltage to improve the device. Even when the discharge occurs, the discharge is terminated only at the divided conductive thin film portion, preventing the elements of the other divided regions from being destroyed,
It is to improve the durability of the electron emission characteristics.

It is another object of the present invention to provide an electron source in which a large number of electron-emitting devices are arranged and arranged, even if an overvoltage is applied to each of the electron-emitting devices, to prevent the devices from being destroyed and to stably maintain the electron-emitting devices. And to improve reliability.

A further object of the present invention is to provide a display device using an electron source in which a large number of electron-emitting devices are arrayed.
Even when a large overvoltage is applied to each electron-emitting device and a discharge occurs in the device, the discharge is terminated only in the divided conductive thin film portions, and display defects are minimized, so that there is no luminance unevenness or image unevenness. It is to provide a high quality image.

[0011]

The configuration of the present invention made to achieve the above object is as follows.

An electron-emitting device according to the present invention is an electron-emitting device comprising a pair of opposing device electrodes formed on a base and a first conductive thin film having an electron-emitting portion formed between the device electrodes. The first conductive thin film between the device electrodes is divided into at least a plurality of first conductive thin films, and at least the plurality of first conductive thin films are connected by a second conductive thin film.

An electron emission device according to the present invention comprises a pair of opposed device electrodes formed on a base and a first conductive thin film having an electron emission portion formed between the device electrodes. In the device, the first conductive thin film is divided at least at a position where the electron-emitting portion is formed, and the second conductive film forming the electron-emitting portion is divided from the first conductive thin film. And is formed so as to straddle the bent portion.

The electron-emitting device of the present invention further has the following features: "the second conductive film is made of carbon and a carbon compound"; and "the electron-emitting device is a surface conduction electron-emitting device." Includes ".

Further, an electron source according to the present invention is characterized in that a plurality of the electron-emitting devices according to the present invention are provided on a substrate.

The electron source according to the present invention further has a feature that it has at least one or more element columns in which a plurality of electron-emitting devices are arranged, and that wirings for driving each of the electron-emitting devices are arranged in a matrix. And that "at least one or more element rows in which a plurality of electron-emitting devices are arranged and wiring for driving each electron-emitting element are arranged in a ladder form".

Further, an image forming apparatus according to the present invention includes the electron source according to the present invention, and an image forming member for forming an image by irradiating an electron beam emitted from the electron source.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the present invention relates to an electron-emitting device, in particular, to a surface conduction electron-emitting device, an electron source having a plurality of the electron-emitting devices arranged, and an image forming apparatus using the electron source. The configuration and operation of each invention will be further described below.

FIG. 1 is a plan view showing an example of a surface conduction electron-emitting device according to a preferred embodiment of the present invention, and FIG. 2 is a schematic cross-sectional view taken along the line AA 'in FIG.

As shown in FIG. 1, a surface conduction electron-emitting device according to the present invention comprises a pair of device electrodes 4 and 5 facing each other on a substrate 1.
And a first conductive thin film 3 connected to the device electrode and having an electron emission portion 8 in a part thereof. The first conductive thin film 3 is divided into three parts, 3a, 3b, and 3c. ing.

As shown in FIG. 2, in the electron emitting portion 8, a part of the first conductive thin film 3 is broken, deformed or deteriorated.
The second conductive film 2 is formed on the first conductive thin film 3 inside and near the gap, including the portion where the gap is formed. Note that the second conductive film 2 has a shape in which the second conductive film 2 faces each other with a gap portion narrower than the gap formed in the first conductive thin film 3. Electron emission is performed from the vicinity of this gap. The electron emitting portion 8 including the gap and the gap itself are formed by the method of manufacturing the first conductive thin film 3 such as the film thickness, film quality, material, and forming conditions described later, and the second conductive film 2 in the activation step described later. Is formed depending on the carbon or carbon compound constituting Therefore, the electron emission section 8
Are not limited to the positions and shapes shown in FIGS. 1 and 2.

According to the present invention, the first conductive thin film 3 between the device electrodes 4 and 5 is divided into at least a plurality of parts, and at least between the plurality of first conductive thin films 3a to 3c constitutes the electron emitting portion 8. It is characterized by being connected by the second conductive film 2.

The resistance of the first conductive thin film 3 which forms a current path for applying a drive voltage to the electron emission section 8 is increased by dividing the first conductive thin film into 3a, 3b and 3c. By limiting an abnormally large current when a discharge occurs, destruction of the element can be prevented.

By connecting the divided first conductive thin film 3 with the second conductive film 2 constituting the electron emitting portion 8, the first conductive thin film 3 is destroyed by an emergency discharge. Even if the current path is cut off, the driving voltage is supplied from the adjacent first conductive thin film 3, and the driving of the element can be continued.

The shape and the number of divisions of the first conductive thin film 3 are appropriately designed depending on the form to be applied, and the distance between adjacent divided first conductive thin films 3a, 3b, 3c is: It is sufficient that the width is smaller than the first conductive thin film width W, and particularly preferably, the interval is several hundred nm to several tens of μm.

The divided shape of the first conductive thin film 3 may be formed by using a photolithography technique, or after forming an integrated conductive thin film, it may be divided by a laser or the like. Any method can be used as long as the divided shape of the conductive thin film can be obtained.

FIG. 3 is a plan view showing another example of the surface conduction electron-emitting device according to a preferred embodiment of the present invention. As shown in FIG. 3, between the device electrodes 4 and 5, the first conductive thin film 3 is divided at least at the position where the electron emitting portion is formed, and the second conductive film 2 constituting the electron emitting portion is ,
The same effect can be obtained even when the first conductive thin film 3 is formed so as to straddle the divided portion.

As the substrate 1, for example, quartz glass, Na
Glass having a reduced impurity content such as glass, blue plate glass, a laminate obtained by laminating SiO ₂ on a blue plate glass by sputtering or the like, ceramics such as alumina, and a Si substrate, but the present invention is not limited thereto. Not something.

The materials of the opposing device electrodes 4 and 5 are as follows.
A general conductor material is used, for example, Ni, Cr, Au,
Mo, W, Pt, Ti, Al, Cu, metal or an alloy such as Pd, and Pd, Ag, Au, printed conductors composed of RuO _2, metal or metal oxide such as Pd-Ag and glass, etc. , In ₂ O ₃ —SnO _2, etc., and a semiconductor conductor material such as polysilicon.

Element electrode interval L, first conductive thin film width W
Is appropriately designed depending on the application form and the like.

The element electrode interval L is preferably several tens nm to several hundreds μm, and more preferably several μm to several tens μm.
m. The first conductive thin film width W is preferably several μm to several hundred μm in consideration of the resistance value of the electrode and the electron emission characteristics.
It is. The thickness of the device electrodes 4 and 5 is several tens nm to several μm, although it depends on the conductivity of the electrode material used.

As a material constituting the first conductive thin film 3, for example, Pd, Pt, Ag, Au, Ti, In, C
u, Cr, Fe, Zn, Sn, Ta, W, and Pb, _{etc., PdO, SnO 2, In 2} O 3, PbO, oxides such as _{Sb 2 O 3, HfB 2,} ZrB 2, La, B 6 , CeB ₆ , Y
Borides such as B ₄ and GdB ₄ , TiC, ZrC, HfC, T
carbides such as aC, SiC, WC, TiN, ZrN, Hf
Examples include nitrides such as N, semiconductors such as Si and Ge, and carbon.

The thickness of the first conductive thin film 3 is preferably set at 0.1. Several nm to several hundred nm, particularly preferably 1 nm to 50 nm.
nm, and the sheet resistance is 10 ² to 10 ⁷ Ω / □.

As a material for forming the second conductive film 2, carbon and a carbon compound are preferable. Here, the carbon and the carbon compound are graphite (indicating both single crystal and polycrystal) and amorphous carbon (indicating amorphous carbon and a mixture thereof with polycrystalline graphite).

The deposited film thickness of the second conductive film 2 is preferably 50 nm or less, more preferably 30 nm or less.

Next, an example of a method for manufacturing the surface conduction electron-emitting device of the present invention shown in FIGS. 1, 2 and 3 will be described with reference to the manufacturing process diagram of FIG. In addition, the process a shown below
4D correspond to FIGS. 4A to 4D.

Step a: After sufficiently washing the substrate 1 with a detergent, pure water and an organic solvent, depositing an element electrode material by a vacuum evaporation method, a sputtering method, or the like, and then depositing the material on the surface of the substrate 1 by a photolithography technique. Device electrodes 4 and 5 are formed.

Step b: An organic metal solution is applied on the substrate 1 provided with the device electrodes 4 and 5 by an ink-jet method.
An organic metal film is formed. As the organic metal solution, a solution of an organic compound containing the metal of the material of the first conductive thin film as a main element can be used. This organic metal film is heated and baked to form a first conductive thin film 3.

Step c: Laser 6 is applied to first conductive thin film 3
To divide the first conductive thin film 3 into a desired pattern.

Step d: Subsequently, an energization process called forming is performed. When electricity is supplied from a power supply (not shown) between the device electrodes 4 and 5, an electron emitting portion 8 having a changed structure is formed at the portion of the first conductive thin film 3. The portion where the first conductive thin film 3 is locally broken, deformed or deteriorated by this energization treatment and the structure is changed is the electron emitting portion 8.

FIG. 5 shows an example of the voltage waveform of the forming.

The voltage waveform is particularly preferably a pulse waveform.
There are a case where a voltage pulse with a constant pulse peak value is applied continuously (FIG. 5A) and a case where a voltage pulse is applied while increasing the pulse peak value (FIG. 5B).

First, the case where the pulse peak value is a constant voltage will be described. T1 and T2 in FIG. 5A are the pulse width and pulse interval of the voltage waveform, for example, T1 is 1 μsec to 10 msec, T2 is 10 μsec to 100 msec,
The peak value (peak voltage at the time of forming) is appropriately selected according to the form of the surface conduction electron-emitting device described above, and an appropriate vacuum degree, for example, a vacuum atmosphere of about 1 × 10 ⁻⁴ to 1 × 10 ⁻⁶ Pa. Below, apply for several seconds to tens of minutes. Note that the voltage waveform to be applied is not limited to the illustrated triangular wave, and a desired waveform such as a rectangular wave can be used. Further, the present invention is not limited to the illustrated unipolar voltage, and an alternating-current waveform of both electrodes may be used.

Next, a case where a voltage pulse is applied while increasing the pulse peak value will be described. T1 and T2 in FIG. 5B are the same as in FIG. 4A, and the peak value (the peak voltage at the time of forming) is increased by, for example, about 0.1 V steps, and is the same as the description of FIG. Under a suitable vacuum atmosphere.

Note that, during the pulse interval T2, a voltage that does not locally destroy, deform, or alter the first conductive thin film 3 (see FIGS. 1, 2, and 3), for example, a voltage of about 0.1 V To measure the element current to determine the resistance value, for example, 1M
Forming is terminated when the resistance exceeds ohms.

Further, an activation step is performed.

The activation step refers to a process of repeating the application of a pulse with the pulse peak value being a constant voltage, as in the description of the forming step, and introducing an organic gas into a vacuum atmosphere, for example, 1 ×. By maintaining carbon at about 10 ^-4 to 1 × 10 ^-6 Pa and depositing carbon and a carbon compound from an organic substance on the forming part and forming a second conductive film, the state of the device current and emission current can be reduced. This is a process that can be significantly improved.

FIG. 6 shows the divided first conductive thin film 3.
The shape in which the second conductive film has developed in the adjacent portions of a and 3b is schematically shown in an enlarged manner. First, as shown in FIG. 6A, the second conductive film 2 is deposited on the forming crack, and further the deposition of the second conductive film 2 proceeds from both ends of the forming portion as the activation process proceeds. The adjacent portions are connected to form an electron emission portion including the second conductive film 2 having the gap 7.

This activation step is preferably performed while, for example, measuring the device current and the emission current, and is completed when the emission current is saturated. In addition, the pulse peak value in the activation step is preferably a peak value of a driving voltage applied when driving the element.

The basic characteristics of the thus obtained surface conduction electron-emitting device of the present invention will be described below.

FIG. 7 is a schematic block diagram showing an example of a measurement evaluation system for measuring the electron emission characteristics of the surface conduction electron-emitting device. First, this measurement evaluation system will be described.

In FIG. 7, the same reference numerals as those in FIG. 1 denote the same members. Reference numeral 71 denotes a power supply for applying a device voltage Vf to the device; 70, an ammeter for measuring a device current If flowing through the first conductive thin film 3 between the device electrodes 4 and 5;
Is an anode electrode for capturing the emission current Ie emitted from the electron emission section 8, 73 is a high voltage power supply for applying a voltage to the anode electrode 74, and 72 is a measurement of the emission current Ie emitted from the electron emission section 8. , A vacuum device 75, and an exhaust pump 76.

The surface conduction electron-emitting device and the anode electrode 74 are installed in a vacuum device 75.
Is equipped with necessary equipment such as a vacuum gauge (not shown),
Measurement and evaluation of the surface conduction electron-emitting device can be performed under a desired vacuum.

The exhaust pump 76 is composed of a normal high vacuum system such as a turbo pump and a rotary pump, and an ultrahigh vacuum system such as an ion pump.
Further, the entire vacuum device 75 and the substrate 1 of the surface conduction electron-emitting device can be heated to about 200 to 300 ° C. by a heater. Note that this measurement evaluation system includes a display panel as described later (see 201 in FIG. 10).
By assembling the display panel and the inside thereof as the vacuum device 75 and the inside thereof in the assembling step, the present invention can be applied to the measurement evaluation and processing in the above-described forming step and activation step.

The basic characteristics of the surface conduction electron-emitting device described below are as follows: the voltage of the anode electrode 74 of the above-mentioned measurement and evaluation system is 1 kV to 10 kV, and the distance H between the anode electrode 74 and the surface conduction electron-emitting device is 2 mm to 8 mm. Usually, measurement is performed.

First, the emission current Ie and the device current If,
FIG. 8 (solid line in FIG. 8) shows a typical example of the relationship between element voltages Vf.
Shown in In FIG. 8, the emission current Ie is the device current I
Since it is significantly smaller than f, it is shown in arbitrary units.

As is apparent from FIG. 8, the surface conduction electron-emitting device has the following three characteristic characteristics with respect to the emission current Ie.

First, when a device voltage Vf higher than a certain voltage (referred to as a threshold voltage: Vth in FIG. 8) is applied to the surface conduction electron-emitting device, the emission current Ie sharply increases. Below the threshold voltage Vth, the emission current Ie is hardly detected. That is, it is a nonlinear element having a clear threshold voltage Vth with respect to the emission current Ie.

Second, since the emission current Ie has a characteristic (referred to as MI characteristic) that monotonically increases with respect to the device voltage Vf, the emission current Ie can be controlled by the device voltage Vf.

Third, the emission charge captured by the anode electrode 74 (see FIG. 7) depends on the time during which the device voltage Vf is applied. That is, the amount of charge captured by the anode electrode 74 can be controlled by the time during which the device voltage Vf is applied.

Because of the above-described characteristic characteristics of the surface conduction electron-emitting device of the present invention, even in an electron source or an image forming apparatus in which a plurality of devices are arranged, the amount of emitted electrons can be easily reduced in accordance with an input signal. It can be controlled and can be applied to various fields.

Next, the arrangement of the surface conduction electron-emitting devices in the electron source of the present invention will be described.

The arrangement of the surface conduction electron-emitting devices in the electron source according to the present invention is not limited to the ladder arrangement as described in the section of the prior art, or to the arrangement of n Y-direction wirings on m X-direction wirings. An arrangement method in which directional wiring is provided via an interlayer insulating layer, and an X-directional wiring and a Y-directional wiring are connected to a pair of device electrodes of a surface conduction electron-emitting device, respectively. This is hereinafter referred to as a simple matrix arrangement. First, the simple matrix arrangement will be described in detail.

According to the above-described basic characteristics of the surface conduction electron-emitting device, when the applied device voltage Vf exceeds the threshold voltage Vth, the electron is expressed by the peak value and the pulse width of the applied pulse voltage. The amount of release can be controlled. On the other hand, below the threshold voltage Vth, almost no electrons are emitted. Therefore, even when a large number of surface conduction electron-emitting devices are arranged, it becomes possible to apply a pulse-like voltage controlled in accordance with an input signal with only a simple matrix wiring and to select individual devices to be driven independently. .

The simple matrix arrangement is based on the above principle, and the structure of an electron source having a simple matrix arrangement, which is an example of the electron source of the present invention, will be further described with reference to FIG.

In FIG. 9, the substrate 1 is a glass plate or the like as described above, and the number and shape of the surface conduction electron-emitting devices 104 arranged on the substrate 1 are appropriately set according to the application. It is.

Each of the m X-direction wirings 102 has external terminals DX1, DX2,.
A conductive metal formed by a vacuum deposition method, a printing method, a sputtering method, or the like is provided thereon. In addition, the materials,
The film thickness and the wiring width are set.

Each of the n Y-directional wirings 103 has external terminals DY1, DY2,... DYn, and is formed in the same manner as the X-directional wiring 102.

These m X-directional wires 102 and n Y wires
An interlayer insulating layer (not shown) is provided between the direction wirings 103, and is electrically separated to form a matrix wiring. Note that both m and n are positive integers.

The interlayer insulating layer (not shown) is, for example, SiO ₂ formed by a vacuum deposition method, a printing method, a sputtering method, or the like, and has a desired shape on the entire surface or a part of the substrate 1 on which the X-directional wiring 102 is formed. In particular, the film thickness, material, and manufacturing method are appropriately set so as to withstand the potential difference at the intersection of the X-direction wiring 102 and the Y-direction wiring 103. Further, the X-direction wiring 102 and the Y-direction wiring 103 are led out as external terminals.

Further, the device electrodes (not shown) facing the surface conduction electron-emitting device 104 are provided with m X-direction wirings 102.
And n Y-directional wirings 103, vacuum deposition method, printing method,
Connection 1 made of conductive metal or the like formed by sputtering or the like
05 are electrically connected.

Here, the m X-directional wirings 102, the n Y-directional wirings 103, the connection 105, and the opposing device electrodes may have the same or some of the constituent elements, even if they are the same. Further, they may be different from each other, and are appropriately selected from the above-described materials of the device electrodes and the like. The wires to these device electrodes may be collectively referred to as device electrodes when the material is the same as the device electrodes. The surface conduction electron-emitting device 104 may be formed on either the substrate 1 or an interlayer insulating layer (not shown).

As will be described later in detail, a scanning signal is applied to the X-direction wiring 102 in order to scan a row of the surface conduction electron-emitting devices 104 arranged in the X-direction in accordance with an input signal. A scanning signal applying unit (not shown) is electrically connected.

On the other hand, a modulation signal (not shown) for applying a modulation signal is applied to the Y-direction wiring 103 in order to modulate each of the rows of the surface conduction electron-emitting devices 104 arranged in the Y direction according to an input signal. The signal applying means is electrically connected. The drive voltage applied to each surface conduction electron-emitting device 104 is supplied as a difference voltage between a scanning signal and a modulation signal applied to the surface conduction electron-emitting device.

Next, an example of the image forming apparatus of the present invention using the electron source of the present invention having the above-described simple matrix arrangement will be described with reference to FIGS. FIG. 10 is a basic configuration diagram of the display panel 201, and FIG.
FIG. 12 shows the display panel 20 of FIG.
1 is a block diagram showing an example of a drive circuit for performing television display according to a television signal of the NTSC system or the like.

In FIG. 10, reference numeral 1 denotes a substrate of an electron source on which the surface conduction electron-emitting device of the present invention is arranged as described above, 111 denotes a rear plate to which the substrate 1 is fixed, and 116 denotes an image on the inner surface of a glass substrate 113. A face plate on which a fluorescent film 114 and a metal back 115, etc., which are forming members, is formed, and 112 is a support frame. Rear plate 1
11, the support frame 112 and the face plate 116 are sealed by applying frit glass or the like to these joints and baking them in the air or in a nitrogen atmosphere at 400 ° C. to 500 ° C. for 10 minutes or more. The container 118 is constituted.

In FIG. 10, reference numerals 102 and 103 denote a pair of device electrodes 4 and 5 of the surface conduction electron-emitting device 104 (FIG. 1).
And X-direction wiring and Y-direction wiring connected to external terminals Dx1 to Dxm and Dy1 to Dy, respectively.
yn.

The envelope 118 includes the face plate 116, the support frame 112, and the rear plate 111, as described above. However, the rear plate 111 is provided mainly for the purpose of reinforcing the strength of the substrate 1. If the substrate 1 itself has sufficient strength, the rear plate 1
11 is unnecessary, and the support frame 112 may be directly sealed to the substrate 1, and the envelope 118 may be configured by the face plate 116, the support frame 112, and the substrate 1. Further, by further providing a support (not shown) called a spacer between the face plate 116 and the rear plate 111, the envelope 118 having sufficient strength against atmospheric pressure can be obtained.

The fluorescent film 114 is composed of only the phosphor 122 in the case of monochrome, but is composed of the phosphor 1 in the case of color.
The arrangement of black stripes (FIG. 11)
(A)) or black matrix (FIG. 11 (b))
Etc. and a phosphor 122. The purpose of providing the black stripes and the black matrix is to make the color separation and the like inconspicuous by making the painted portions between the phosphors 122 of the three primary colors necessary in the case of color display black, and to reflect external light on the fluorescent film 114. The purpose is to suppress a decrease in contrast. As a material of the black conductive material 121, not only a material mainly containing graphite, which is usually used, but also other materials can be used as long as the material has conductivity and transmits and reflects less light. .

As a method of applying the phosphor 122 to the glass substrate 113, a precipitation method or a printing method is used regardless of monochrome or color.

Further, as shown in FIG.
Usually, a metal back 115 is provided on the inner side of 14. The purpose of the metal back 115 is to use the phosphor 122 (FIG. 1).
0), the light to the inner surface side is reflected to the face plate 116 side to improve the brightness, the light acts as an electrode for applying an electron beam acceleration voltage from the high voltage terminal Hv, and Protection of the phosphor 122 from damage due to collision of negative ions generated in the container 118. The metal back 115 can be manufactured by performing a smoothing process (usually called filming) on the inner surface of the fluorescent film 114 after the fluorescent film 114 is manufactured, and then depositing Al by vacuum evaporation or the like.

The face plate 116 may be provided with a transparent electrode (not shown) on the outer surface side of the fluorescent film 114 in order to further increase the conductivity of the fluorescent film 114.

At the time of performing the above-mentioned sealing, in the case of color, since the phosphors 122 of each color must correspond to the surface conduction electron-emitting devices 104, it is necessary to perform sufficient alignment.

The inside of the envelope 118 is evacuated to a degree of vacuum of about 1 × 10 ⁻⁵ Pa through an exhaust pipe (not shown) and sealed.
In addition, a getter process may be performed immediately before or after sealing the envelope 118. In this method, a getter (not shown) arranged at a predetermined position in the envelope 118 is heated by a heating method such as resistance heating or high-frequency heating.
This is a process for forming a deposition film. The getter is usually composed mainly of Ba or the like.
This is for maintaining a degree of vacuum of 10 ⁻³ to 1 × 10 ⁻⁵ Pa.

The above-described forming and the subsequent manufacturing steps of the surface conduction electron-emitting device are usually performed in the envelope 1
This is performed immediately before or after the sealing of 18, and the contents thereof are as described above.

The display panel 201 described above is, for example, shown in FIG.
Can be driven by a driving circuit as shown in FIG.
In FIG. 12, reference numeral 201 denotes the display panel.
202 is a scanning circuit, 203 is a control circuit, 204 is a shift register, 205 is a line memory, 206 is a synchronization signal separation circuit, 207 is a modulation signal generator, and Vx and Va are DC voltage sources.

As shown in FIG. 12, the display panel 20
1 is connected to an external electric circuit via external terminals Dx1 to Dxm, external terminals Dy1 to Dyn, and a high voltage terminal Hv. Of these, the external terminals Dx1 to Dx1
In xm, surface conduction electron-emitting devices provided in the display panel 201, that is, a group of surface conduction electron-emitting devices arranged in a matrix of m rows and n columns are sequentially arranged in a row (n elements). A scanning signal for driving is applied.

On the other hand, the external terminals Dy1 to Dyn
A modulation signal for controlling an output electron beam of each element in one row selected by the scanning signal is applied. The high voltage terminal Hv is connected to a DC voltage source Va at, for example, 10 kV.
Is supplied. This is an accelerating voltage for applying sufficient energy to the electron beam output from the surface conduction electron-emitting device to excite the phosphor.

The scanning circuit 202 has m switching elements therein (schematically indicated by S1 to Sm in FIG. 12).
Each of the switching elements S1 to Sm selects either the output voltage of the DC voltage source Vx or 0 V (ground level) and is electrically connected to the external terminals Dx1 to Dxm of the display panel 201. Things. Each of the switching elements S1 to Sm includes a control circuit 203
Operates on the basis of the control signal Tscan output by the device, and in fact, it can be easily configured by combining elements having a switching function such as an FET, for example.

In the present embodiment, the DC voltage source Vx has a threshold drive voltage applied to the unscanned surface conduction electron-emitting device based on the characteristics (threshold voltage) of the surface conduction electron-emitting device. It is set to output a constant voltage that is equal to or lower than the value voltage.

The control circuit 203 has a function of coordinating the operation of each unit so that appropriate display is performed based on an image signal input from the outside. A synchronization signal Tsyn sent from a synchronization signal separation circuit 206 described below.
Based on c, each control signal of Tscan, Tsft, and Tmry is generated for each unit.

The synchronizing signal separating circuit 206 is a circuit for separating a synchronizing signal component and a luminance signal component from an NTSC system television signal input from the outside. ) With the circuit,
It can be easily configured. Sync signal separation circuit 206
The sync signal separated by is composed of a vertical sync signal and a horizontal sync signal, as is well known. Here, it is illustrated as Tsync for convenience of explanation. On the other hand, the luminance signal component of the image separated from the television signal is referred to as D for convenience.
This is illustrated as an ATA signal. This DATA signal is input to the shift register 204.

The shift register 204 is for serially / parallel converting the DATA signal input serially in time series for each line of an image, and is based on a control signal Tsft sent from the control circuit 203. Operate. This control signal Tsft is supplied to the shift register 20
4 may be rephrased as the shift clock. Also,
One line of serial / parallel converted image (equivalent to drive data for n elements of surface conduction electron-emitting device)
Are output from the shift register 204 as n parallel signals Id1 to Idn.

The line memory 205 is a storage device for storing data of one line of an image for a required time, and stores the contents of Id1 to Idn as appropriate according to a control signal Tmry sent from the control circuit 203. The stored contents are output as I'd1 to I'dn and input to the modulation signal generator 207.

The modulation signal generator 207 is a signal line for appropriately driving and modulating each of the surface conduction electron-emitting devices in accordance with each of the image data I'd1 to I'dn.
The output signal is applied to the surface conduction electron-emitting devices in the display panel 201 through the external terminals Dy1 to Dyn.

As described above, the surface conduction electron-emitting device has a distinct threshold voltage for electron emission, and electron emission occurs only when a voltage exceeding the threshold voltage is applied. For voltages exceeding the threshold voltage,
The emission current also changes according to the change in the voltage applied to the surface conduction electron-emitting device. By changing the material, configuration, and manufacturing method of the surface conduction electron-emitting device, the value of the threshold voltage and the degree of change of the emission current with respect to the applied voltage may be changed. I can say the thing.

That is, when a pulse-like voltage is applied to the surface conduction electron-emitting device, electron emission does not occur even if a voltage lower than the threshold voltage is applied, but a voltage exceeding the threshold voltage is applied. In this case, electron emission occurs. At that time, first, it is possible to control the intensity of the output electron beam by changing the peak value of the voltage pulse. Second, by changing the width of the voltage pulse, it is possible to control the total amount of charges of the output electron beam.

Accordingly, as a method of modulating the surface conduction electron-emitting device according to an input signal, there are a voltage modulation method and a pulse width modulation method. In the case of performing the voltage modulation method, the modulation signal generator 207 generates a voltage pulse having a fixed length, and uses a voltage modulation circuit capable of appropriately modulating the pulse peak value according to input data. In the case of performing the pulse width modulation method, the modulation signal generator 207 generates a voltage pulse having a constant peak value, but a pulse width modulation method circuit capable of appropriately modulating the pulse width according to input data. Used.

The shift register 204 and the line memory 20
Reference numeral 5 may be a digital signal type or an analog signal type, as long as it can perform serial / parallel conversion and storage of an image signal at a predetermined speed.

When the digital signal type is used, it is necessary to convert the output signal DATA of the synchronization signal separation circuit 206 into a digital signal. This can be achieved by providing an A / D converter at the output of the synchronization signal separation circuit 206.

In connection with this, the line memory 20
Depending on whether the output signal of 5 is a digital signal or an analog signal,
The circuit provided in modulation signal generator 207 is slightly different.

That is, in the case of a voltage modulation method using a digital signal, a well-known D / A conversion circuit may be used as the modulation signal generator 207, and an amplification circuit or the like may be added as necessary. Further, in the case of a pulse width modulation method using a digital signal, the modulation signal generator 207 includes, for example, a high-speed oscillator, a counter (counter) for counting the number of waves output from the oscillator, an output value of the counter, and an output value of the memory. It can be easily configured by using a circuit in which comparators for comparison are combined. Further, if necessary, an amplifier may be added for amplifying the voltage of the pulse-width-modulated signal output from the comparator to the drive voltage of the surface-conduction electron-emitting device.

On the other hand, in the case of a voltage modulation system using an analog signal, an amplification circuit using a well-known operational amplifier or the like may be used as the modulation signal generator 207, and a level shift circuit or the like may be added as necessary. You may. In the case of a pulse width modulation method using an analog signal, for example, a well-known voltage-controlled oscillation circuit (VCO) may be used, and a voltage is amplified to a drive voltage of a surface conduction electron-emitting device as necessary. May be added.

The image forming apparatus of the present invention having the display panel 201 and the driving circuit as described above has the external terminals Dx1 to Dx1.
By applying a voltage from Dxm and Dy1 to Dyn, electrons can be emitted from an arbitrary electron-emitting device 104, and a high voltage is applied to the metal back 115 or a transparent electrode (not shown) through the high voltage terminal Hv. A television display can be performed according to an NTSC television signal by exciting and emitting light generated by accelerating the beam and colliding the accelerated electron beam with the fluorescent film 114.

The configuration described above is a schematic configuration necessary for obtaining the image forming apparatus of the present invention used for display and the like. For example, detailed parts such as materials of each member are limited to those described above. Instead, it is appropriately selected so as to be suitable for the use of the image forming apparatus. Although the NTSC system has been described as an example of the input signal, the image forming apparatus of the present invention is not limited to this, and may employ another system such as a PAL or SECAM system. For example, a high-definition TV system such as a MUSE system may be used.

Next, an example of a trapezoidal arrangement of electron sources and an image forming apparatus of the present invention using the same will be described with reference to FIGS.
4 will be described.

In FIG. 13, reference numeral 1 denotes a substrate; 104, a surface conduction electron-emitting device; and 304, common wirings for connecting the surface conduction electron-emitting devices 104, each having ten external terminals D1 to D10. are doing.

The surface conduction electron-emitting device 104 is
A plurality is arranged in parallel on the top. This is called an element row. These element rows are arranged in a plurality of rows to constitute an electron source.

By applying an appropriate drive voltage between the common wiring 304 of each element row (for example, the common wiring 304 of the external terminals D1 and D2), each element row can be driven independently. That is, a voltage exceeding the threshold voltage may be applied to an element row where electron beams are to be emitted, and a voltage lower than the threshold voltage may be applied to an element row where electron beams are not desired to be emitted. Such a drive voltage is applied to the common lines D2 to D9 located between the element rows, and the common lines 304 adjacent to each other, that is, the external terminals D adjacent to each other.
2 and D3, D4 and D5, D6 and D7, and D8 and D9 can be formed as a single common wiring.

FIG. 14 is a diagram showing the structure of a display panel 301 provided with the above-described trapezoidal arrangement of electron sources.

In FIG. 14, reference numeral 302 denotes a grid electrode,
Reference numeral 303 denotes an opening through which electrons pass, D1 to Dm denote external terminals for applying a voltage to each surface conduction electron-emitting device, and G1 to Gn denote terminals connected to the grid electrode 302. Further, the common wiring 304 between each element row is formed on the substrate 1 as an integral same wiring.

In FIG. 14, the same reference numerals as those in FIG. 10 denote the same members, and the major difference between the display panel 201 using the electron sources in the simple matrix arrangement shown in FIG. The point is that a grid electrode 302 is provided between the electrodes 116.

The grid electrode 302 is provided between the substrate 1 and the face plate 116 as described above. The grid electrode 302 is capable of modulating an electron beam emitted from the surface conduction electron-emitting device 104. The grid electrode 302 applies the electron beam to a stripe-shaped electrode provided orthogonally to the ladder-shaped element rows. In order to pass
A circular opening 303 is provided one by one corresponding to each surface conduction electron-emitting device 104.

The shape and arrangement position of the grid electrode 302
It is not always necessary that the openings 303 are formed as shown in FIG. 14, and a large number of openings 303 may be provided in a mesh shape.
4 may be provided around or in the vicinity.

The external terminals D1 to Dm and G1 to Gn are connected to a drive circuit (not shown). A modulation signal for one line of an image is applied to the column of the grid electrode 302 in synchronization with the sequential driving (scanning) of the element rows one by one, so that each electron beam is applied to the fluorescent film 114. The irradiation can be controlled and the image can be displayed line by line.

As described above, the image forming apparatus of the present invention
It can be obtained by using any of the electron sources of the present invention in a simple matrix arrangement or a trapezoidal arrangement, and is suitable not only for the above-described television broadcast display device, but also as a video conference system and a display device such as a computer. A device is obtained. Further, it can be used as an exposure device of an optical printer including a photosensitive drum and the like.

[0117]

The present invention will be further described with reference to the following examples.

Example 1 The surface conduction electron-emitting device shown in FIGS. 1 and 2 was produced as the surface conduction electron-emitting device of this example.

The manufacturing method of this embodiment will be described with reference to FIG. The following steps a to d correspond to (a) to (d) in FIG.

Step a: A blue plate substrate was used as the substrate 1, and this was sufficiently washed with an organic solvent, and then device electrodes 4 and 5 made of Pt were formed. At this time, the element electrode interval L is 10 μm.
m and device electrodes 4 and 5 having a width of 300 μm.

Step b: Substrate 1 provided with device electrodes 4 and 5
Then, droplets of a solution having an organometallic compound are applied to the conductive thin film region by an ink-jet method to form an organometallic thin film, which is then baked in a clean oven at 300 ° C. for 10 minutes in the air to perform palladium oxide ( A fine particle film (first conductive thin film 3) composed of PdO) fine particles (average particle diameter: 60 °) was formed. The thickness of the fine particle film is 0.02 μm,
The sheet resistance was 2 × 10 ⁴ Ω / □.

Step c: The first conductive thin film 3 is irradiated with a laser beam 6 (the laser trimming device main body is not shown) to cut and divide the first conductive thin film 3 into a desired pattern.

Step d: The substrate 1 on which the device electrodes 4 and 5 and the first conductive thin film 3 are formed is set in the vacuum apparatus 75 of the measurement and evaluation system shown in FIG. ,
The inside of the vacuum device 75 was set to a degree of vacuum of about 10 ⁻⁴ Pa. Thereafter, a voltage was applied between the device electrodes 4 and 5 by the power supply 71 for applying the device voltage Vf, and the electron emitting portion 8 was formed by performing a forming process. The voltage waveform shown in FIG. 5A was used for the forming process.

In this embodiment, T1 in FIG.
sec, T2 is 10 msec, the peak value of the triangular wave (peak voltage at the time of forming) is 10 V, and about 60 s.
The forming process was performed during ec.

Subsequently, benzonitrile was introduced into a vacuum atmosphere and the degree of vacuum was maintained at about 1 × 10 ⁻⁴ Pa,
The activation process was performed at a peak voltage of V. At this time, about 30m
When the device current If was saturated at “in”, the activation process was terminated.

The measurement of the electron emission characteristics of the plurality of devices of this example manufactured as described above was performed using the above-described measurement evaluation system. The measurement conditions were as follows: the distance H between the anode electrode 74 and the device was 5 mm, and the potential of the anode electrode 74 was 1 k.
V, the device voltage Vf was 14 V, and the degree of vacuum in the vacuum device 75 at the time of measuring the electron emission characteristics was 1 × 10 ⁻⁴ Pa.

As a result, the device of this embodiment has a device voltage of 1
Even when an instantaneous overvoltage exceeding 4 V by several volts was applied to the device, no discharge breakdown of the device occurred.

[Embodiment 2] In this embodiment, a number of surface conduction electron-emitting devices as shown in FIGS. 1 and 2 are arranged in a simple matrix and an electron source as shown in FIG. 9 is used. An example in which an image forming apparatus as shown in FIG. 10 is manufactured will be described.

In the production of the electron source, each pattern of the device electrodes 4 and 5 and the divided first conductive thin film 3 described in the first embodiment is expanded to simultaneously manufacture a large number of surface conduction electron-emitting devices. At the same time, the X-directional wiring (also referred to as lower wiring) 102 and the Y-directional wiring (also referred to as upper wiring) 103 connected to the element electrode 4 and the element electrode 5, respectively, were formed via an insulating layer.

An example in which an image forming apparatus is formed using an unformed electron source substrate manufactured as described above will be described with reference to FIGS.

First, after fixing the substrate 1 of the unformed electron source to the rear plate 111, the face plate 116 (the fluorescent film 114 serving as an image forming member on the inner surface of the glass substrate 113) is placed 5 mm above the substrate 1. The support frame 112 is formed by forming a metal back 115.
, The face plate 116, the support frame 11
2. Frit glass was applied to the joint portion of the rear plate 111, and was baked at 400 ° C. to 500 ° C. in the air for 10 minutes or more to seal (see FIG. 10). The fixing of the substrate 1 to the rear plate 111 was also performed using frit glass.

The fluorescent film 114 serving as an image forming member
Is composed of only a phosphor in the case of monochrome, but in this embodiment, the phosphor is in a stripe shape (see FIG. 11A).
And a black stripe is first formed with the black conductive material 121, and the phosphors 1 of each color are formed in the gaps by a slurry method.
22 was applied to form a fluorescent film 114. Black conductive material 1
For 21, a material mainly containing graphite, which is commonly used, was used.

Further, a metal back 115 was provided on the inner surface side of the fluorescent film 114. The metal back 115 is the fluorescent film 1
After the fabrication of 14, the inner surface of the fluorescent film 114 is subjected to a smoothing process (usually called filming), and
1 was produced by vacuum evaporation.

In the face plate 116, a transparent electrode may be provided on the outer surface side of the fluorescent film 114 in order to further increase the conductivity of the fluorescent film 114. It is omitted because it has the property.

When the above-mentioned sealing is performed, in the case of color, the phosphors 122 of each color and the electron-emitting devices 104 must correspond to each other.

The atmosphere in the envelope 118 completed as described above is exhausted by a vacuum pump through an exhaust pipe (not shown), and after reaching a sufficient degree of vacuum, the external terminals Dx1 to Dxm
A voltage was applied between the device electrodes 4 and 5 of each of the surface conduction electron-emitting devices 104 through Dy1 to Dyn, and a forming process was performed in the same manner as in Example 1 to produce the electron-emitting portion 8.

Subsequently, benzonitrile was introduced into a vacuum atmosphere, and the degree of vacuum was maintained at about 1 × 10 ⁻⁴ Pa, and 15
The activation process was performed at a peak voltage of V. At this time, about 30m
When the device current If was saturated at “in”, the activation process was terminated.

After that, the envelope 1 is passed through an exhaust pipe (not shown).
The 18 and ^{1.3 × 10 -4.5 Pa (10 -6.5} Torr) vacuum degree of about, welded by heat exhaust pipe with a gas burner, was sealed in the envelope 118. Finally, gettering was performed by a high-frequency heating method to maintain the degree of vacuum after sealing. The getter contained Ba as a main component.

The display panel 201 constructed using the electron sources arranged in a simple matrix as described above (see FIG. 10).
In the above, the scanning signal and the modulation signal are applied to the respective surface conduction electron-emitting devices 104 by signal generating means (not shown) through the external terminals Dx1 to Dxm and Dy1 to Dyn, thereby emitting electrons, and the high voltage terminal Hv. A high voltage of several kV or more was applied to the metal back 115 to accelerate the electron beam, collide with the fluorescent film 114, and excite and emit light to display an image.

As a result, the electron source manufactured in this embodiment is
Even when an overvoltage equal to or higher than the drive voltage is applied to the element by applying a surge noise or the like from outside the drive circuit, discharge breakdown does not occur, no defective pixels are generated, and high-quality image display can be maintained.

In the present image forming apparatus, in particular, since the display panel 201 according to the present invention can be easily made thin, the depth of the display device can be reduced. In addition, since it is easy to enlarge the screen, the brightness is high, and the viewing angle characteristics are excellent, it is possible to display a realistic and powerful image with good visibility, and discharge breakdown of elements that cause pixel defects And a highly reliable image forming apparatus can be realized.

[0142]

As described above, according to the present invention, the following effects can be obtained.

1) It is possible to prevent discharge breakdown occurring in the electron-emitting portion of the electron-emitting device due to an overvoltage, and to improve the reliability of the electron-emitting characteristics.

2) Even if a discharge occurs in the electron-emitting portion of the electron-emitting device due to a larger overvoltage, only a part of the divided conductive thin film is discharged and the driving voltage is supplied from another conductive thin film. As a result, the durability of the electron emission characteristics can be improved.

3) In an electron source in which a large number of electron-emitting devices are arrayed and an image forming apparatus using the electron source, it is possible to prevent the occurrence of pixel defects in a display image even when an overvoltage is applied.

[Brief description of the drawings]

FIG. 1 is a schematic view showing components of a basic electron-emitting device according to the present invention.

FIG. 2 is a sectional view taken along line A-A 'of FIG.

FIG. 3 is another schematic diagram showing a component of a basic electron-emitting device according to the present invention.

FIG. 4 is a diagram illustrating an example of a method for manufacturing a basic component of an electron-emitting device according to the present invention.

FIG. 5 is a diagram showing an example of a voltage waveform used for forming and activating according to the present invention.

FIG. 6 is a schematic view showing a state in which a second conductive thin film according to the present invention is formed.

FIG. 7 is a diagram showing an evaluation system for measuring the electron emission characteristics of the electron-emitting device according to the present invention.

FIG. 8 is a diagram showing voltage Vf characteristics of an emission current Ie and an element current If according to the present invention.

FIG. 9 is a diagram showing a configuration of an electron source having a simple matrix arrangement according to the present invention.

FIG. 10 is a basic configuration diagram of an image forming apparatus according to the present invention.

FIG. 11 is a diagram illustrating an example of a fluorescent film of the image forming apparatus according to the present invention.

FIG. 12 is a block diagram illustrating an example of a drive circuit of the image forming apparatus according to the present invention.

FIG. 13 is a view showing a configuration of a trapezoidal-shaped electron source according to the present invention.

FIG. 14 is a basic configuration diagram of an image forming apparatus using a trapezoidal-shaped electron source according to the present invention.

FIG. 15 is a schematic view showing a configuration part of a conventional electron-emitting device.

FIG. 16 is a schematic view showing discharge breakdown occurring in a conventional electron-emitting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 The 2nd electroconductive film which comprises an electron emission part 3 1st electroconductive thin film 4, 5 Device electrode 6 Laser light 7 Gap 8 Electron emission part

Claims (8)

[Claims] An electron-emitting device comprising a pair of opposing device electrodes formed on a base and a first conductive thin film having an electron-emitting portion formed between the device electrodes. The first conductive thin film is divided into at least a plurality of first conductive thin films, and the plurality of first conductive thin films are connected by a second conductive film constituting an electron emission portion. element. 2. An electron-emitting device comprising: a pair of opposing element electrodes formed on a base; and a first conductive thin film having an electron-emitting portion formed between the element electrodes. The conductive thin film is divided at least at the position where the electron-emitting portion is formed, and the second conductive film constituting the electron-emitting portion is formed across the divided portion of the first conductive thin film. An electron-emitting device, comprising: 3. The electron-emitting device according to claim 1, wherein the second conductive film is made of carbon and a carbon compound. 4. The electron-emitting device according to claim 1, wherein said electron-emitting device is a surface conduction electron-emitting device. 5. An electron source comprising a plurality of the electron-emitting devices according to claim 1 provided on a substrate. 6. The device according to claim 5, wherein the device has at least one device row in which a plurality of electron-emitting devices are arranged, and wirings for driving each of the electron-emitting devices are arranged in a matrix. Electron source. 7. The device according to claim 5, wherein the device has at least one element array in which a plurality of electron-emitting devices are arranged, and wirings for driving each electron-emitting device are arranged in a ladder shape. Electron source. 8. An image forming apparatus comprising: the electron source according to claim 4; and an image forming member that forms an image by irradiating an electron beam emitted from the electron source. .