JPH08250046A - Image forming device and manufacture thereof - Google Patents

Abstract

PURPOSE: To make the length of an electron emitting part constant to prevent decrease of brightness and its nonuniformity of an image, by forming both end parts in a row direction of a pair of element electrodes arranged on an electron source substrate so as to be covered with an insulating film. CONSTITUTION: On the surface of an insulating substrate 1, a surface conduction electron emitting element formed of an element electrode 2 provided with an electron emitting part is arranged, to obtain an electron source of an image forming device. Here is formed an insulating film 6 so as to cover both end parts in a row direction Y of a pair of element electrodes. A length in the row direction of a pair of these element electrodes is formed preferably longer than a length in a row direction of a pair of the element electrodes not covered with the insulating film by 60μm or more. Row direction wiring 6 connected to an element electrode 2, line direction wiring 8 and the insulating film 6 are preferably formed by a screen method, thus to enable a pattern position deviation to reduce to a minium limit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus using a surface conduction electron-emitting device and a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventional flat panel image forming apparatuses include simple matrix liquid crystal display (LCD), thin film transistor liquid crystal display (TFT / LCD), plasma display (PDP), low-speed electron beam fluorescent display (VFD) and the like. There is.

As one of the light emitting methods in these image forming apparatuses, there is a method of causing a phosphor to emit light by using an electron emitting element. A surface conduction electron-emitting device is generally known as this electron-emitting device (MI Elins).
on, Radio Eng. Electron Phy
s. , 10, (1965)). This electron-emitting device utilizes a phenomenon in which electrons are emitted when a current is applied to a small-area thin film formed on a substrate in a direction parallel to the film surface.

As the thin film of the surface conduction electron-emitting device,
SnO ₂ thin film (MI Elinson, Radio)
Eng. Electron Phys. , 10, (19
65)), Au thin film (G. Dittmer, Thin.
Solid Films, 9, 317 (1972)),
In ₂ O ₃ / SnO ₂ thin film (M. Hartwell an
d C. G. Fonstad, IEEE Trans.
ED Conf. , 519 (1975)), carbon thin film (Hiroshi Araki et al., Vacuum, 26, 1, 22 (198).
3)) etc. have been reported.

A typical example of the surface conduction electron-emitting device is shown in FIG. The structure of this electron-emitting device is as described in M. Har
According to Twell, 1 is an insulating substrate, 12 is an electron emitting portion forming thin film, and 3 is an electron emitting portion. The electron emission portion forming thin film (12) is formed by forming an H-shaped metal oxide thin film on the substrate (1) by sputtering. Next, the electron emission portion (3) is formed by an energization process called forming. The forming means that a voltage is applied to both ends of the thin film (12) for forming an electron emitting portion to locally destroy, deform, and change the thin film (12) for forming an electron emitting portion, and an electron having a high electrical resistance is formed. Forming the emitting portion (3). In addition, the electrons may be emitted from the vicinity of the cracks in the thin film (12) for forming the electron emitting portion.

On the other hand, the applicant of the present invention has found that a thin film (12) for forming an electron emitting portion, which is made of an electron emitting material in which fine particles are dispersed and arranged.
By arranging between a pair of device electrodes, a new surface conduction electron-emitting device was developed, and this was technically disclosed (USP 5,066,883). This electron-emitting device is
Since the electron emission position can be controlled more precisely than the conventional one, the electron emitting devices can be arranged with higher accuracy. A typical example of this electron-emitting device is shown in FIG. Figure 6
In the above, 1 is an insulating substrate, 2 is an element electrode for electrical connection, 12 is an electron emitting portion forming thin film made of an electron emitting material in which fine particles are dispersed and arranged, and 3 is an electron emitting portion.

A large number of the surface conduction electron-emitting devices described above are formed on a substrate to produce an electron source substrate. The electron source substrate is combined with a plate having a phosphor and then placed in a vacuum envelope to form an image forming device. In the vacuum envelope, electrons are emitted from the electron source substrate and the electrons irradiate the phosphor of the plate.

The present applicant is studying the production of an electron source substrate using the above surface conduction electron-emitting device. An example of this electron source substrate is shown in FIG. FIG. 7 shows a part of an electron source substrate including two electron-emitting devices in the row direction and two in the column direction (a total of three matrixes) out of a large number of electron-emitting devices formed in the matrix direction. Is.

As a method of manufacturing such an electron source substrate, there are a photolithography method, a printing method and the like. The photolithographic method has good patterning accuracy. But 4
In the case of manufacturing an image display device having a large area of 0 inch or more, a large-sized film forming device and an exposure device are required, and a large amount of process materials to be used are also required, resulting in an increase in cost. Therefore, when manufacturing an image forming apparatus having a large area, it is preferable to use a printing method in terms of cost.

[0010]

However, the printing method has a problem that the pattern dimensional accuracy and the alignment accuracy are low when the electron-emitting device is formed on the substrate to manufacture the electron source substrate. Particularly, in FIGS. 7 and 8, problems occur in the pattern dimensional accuracy and the alignment accuracy of the device electrode (2) and the insulating film (6). That is, as shown in FIG. 8A, the two insulating films (6) should be formed so that the element electrode (2) is located at the center thereof (at this time, P ₁ = Q). , The two insulating films (6) are displaced as shown in FIG. 8 (b). As a result, the length in the column direction of the pair of device electrodes not covered with the insulating film becomes shorter, and the length in the column direction of the electron emitting portion formed between the device electrodes becomes shorter (P ₁ > P _2). = P ₁ -R _1). Due to this, the brightness is lowered or the brightness becomes uneven. In FIG. 8, Q is the length of the element electrode (2) in the column direction, P ₁ and P ₂
Is the length in the column direction of the device electrode not covered by the insulating film, R
Reference numeral ₁ denotes the length in the column direction of the device electrode covered by the positional deviation of the insulating film (6).

Therefore, an object of the present invention is to make the length of the electron emitting portion between the pair of device electrodes constant even if the position shift occurs during the formation of the insulating film of the electron source substrate, so that the brightness of the image does not decrease. Moreover, it is an object of the present invention to provide an image forming apparatus with less uneven brightness. Another object is to provide an electron source substrate by a printing method and provide a large-screen image forming apparatus at low cost.

[0012]

The present inventor has completed the present invention as a result of various studies in order to achieve the above object. That is, the present invention provides an image forming apparatus including an electron source substrate on which surface conduction electron-emitting devices are arranged,
The present invention relates to an image forming apparatus, wherein an insulating film is formed so as to cover both ends of a pair of element electrodes in the column direction. The present invention also relates to a method for manufacturing the image forming apparatus, in which the wiring and the insulating film on the electron source substrate are formed by screen printing.

The present invention will be described in detail below.

FIG. 1 is a plan view of the electron source substrate of the present invention (in the figure, the X-axis direction is the row direction and the Y-axis direction is the column direction). This FIG. 1 shows that two of the electron-emitting devices formed in the matrix direction on the insulating substrate (1) are arranged in the row direction.
3 shows a part of an electron source substrate including two element electrodes in the column direction (three in matrix). Further, FIG. 2 shows a sectional view taken along the line AA of FIG.

The present invention is characterized in that an insulating film is formed on such an electron source substrate so as to cover both ends in the column direction of the pair of device electrodes. That is, FIG.
In (a), the length (Q) of the device electrode (2) is determined by the length in the column direction of the device electrode not covered with the insulating film, that is, the distance (P ₁ ) between the pair of insulating films (6). The feature is that it is long. The positional deviation of the pattern in the printing method is at most ±
Since it is about 30 μm, it is desirable that it is longer than 60 μm. By setting the lengths of the element electrodes in this way, as shown in FIG. 2B, a row of element electrodes that is not covered with the insulating film even if a positional deviation (R ₂ ) occurs when the insulating film is formed. The length in the direction (P ₂ ) is constant (P ₂ = P ₁ ). Therefore, when the thin film (12) for forming the electron emission portion is formed between the pair of device electrodes not covered with the insulating film (see FIG. 1).
Since the length of the electron emitting portion (3) formed in this thin film (12) is constant regardless of the positional deviation of the insulating film, the decrease in brightness is suppressed and the uneven brightness is also reduced.

The upper limit of the above-mentioned length of the element electrode is less than the length of the pixel pitch (see FIG. 4), and in actuality, it is shorter than the pixel pitch by about 50 μm because of the printing resolution.

In FIG. 1, the electrode interval between the pair of device electrodes (2) is preferably several μm to several hundred μm, and the thickness of the device electrodes (2) is several hundred to several thousand angstroms. The lengths in the row direction and the column direction of the device electrodes are each preferably several hundreds to 1000 μm.

The electron emitting portion forming thin film (12) formed between the pair of device electrodes preferably has a thickness of several tens to several thousands angstroms.

The connection electrode (4) and the column-direction wiring (5) are connected to the device electrode (2), respectively. The thickness of these connection electrodes and the wiring in the column direction is suitably several μm to several tens of μm. The length of the connection electrodes in the row direction is suitably several tens to several hundreds of μm, and the length of the connection electrodes in the column direction is suitably several hundreds μm. The length of the column-direction wiring in the row direction is preferably 100 to 300 μm, and the length of the column-direction wiring in the column direction is based on the design and is formed according to the length of the substrate in the column direction.

The insulating film (6) is formed in a strip shape and is installed so as to intersect the column-direction wiring (5). A suitable thickness of this insulating film is 30 to 50 μm. The length of the insulating film in the row direction is based on the design, and is formed according to the length of the substrate in the row direction. The length of the insulating film in the column direction is preferably 200 to 600 μm.

A row-direction wiring (8) is provided over the strip-shaped insulating film (6). The row-direction wiring (8) is connected to the connection electrode (4) through the contact hole (7). A suitable thickness of the wiring in the row direction is 40 to 60 μm. The length in the row direction of the row-direction wiring is formed according to the length in the row direction of the substrate based on the design, and the length in the column direction of the row-direction wiring is preferably 100 to 500 μm.

An insulating material is used as the material of the substrate. For example, quartz glass, glass with a reduced content of impurities such as Na, soda-lime glass, and SiO by a sputtering method or the like.
Examples include soda-lime glass laminated with ₂ , ceramics such as alumina.

As a material for the insulating film, a general glass paste can be used.

The material of the device electrodes, connection electrodes, row-direction wirings and column-direction wirings is not limited as long as it has conductivity. For example, Ni, Cr, Au, Mo, W, Pt.
Metals such as Ti / Al / Cu / Pd or their alloys,
_{Pd · Ag · Au · RuO 2} · Pd-Ag or the like of the metal or metal oxide and printed conductor composed of a glasses, semiconductor materials such as polysilicon, a transparent conductive material such as In ₂ O ₃ -SnO _2, etc. Is mentioned.

Examples of the material of the thin film for forming the electron emitting portion include Pt, Ru, Ag, Au, Ti, In, Cu, and C.
r ・ Fe ・ Zn ・ Sn ・ Ta ・ W ・ Pb ・ Ag-Mg ・
Ni-Cu or the like _{metal, PdO · SnO 2 · In 2} O 3 · P
oxides such as _{bO · Sb 2 O 3, HfB} 2 · ZrB 2 · LaB
Borides of ₆・ CeB ₆・ YB ₄・ GdB _4, etc., TiC ・ Z
Carbide such as rC / HfC / TaC / SiC / WC, Ti
Examples thereof include nitrides such as N / ZrN / HfN, semiconductors such as Si / Ge, and carbon.

The thin film for forming the electron emitting portion is a fine particle film of the above material. A fine particle film is an aggregate of a plurality of fine particles in a film form, and its fine structure has a state in which the fine particles are individually dispersed and arranged, and the fine particles are adjacent to each other or overlap each other (including island shape). It has the structure of.

The above structure constitutes one surface conduction electron-emitting device unit (wiring unit including one surface conduction electron-emitting device), and a large number of these units are provided in a matrix on the substrate (1). An electron source substrate is formed.

Next, a method of manufacturing the electron source substrate of the present invention will be described.
This will be described with reference to (I) to (V) of FIG. FIG. 4 shows a case where a total of 9 surface conduction electron-emitting device units are arranged in 3 rows and 3 columns.

Step (I): A conductive thin film made of the above-mentioned conductive material used for the device electrode is formed on the surface of the substrate (1) which has been thoroughly washed. This substrate is finely processed by photolithography to form a pattern of device electrodes (2) as shown in FIG. 4 (I). At this time, the insulating film (6)
The pattern dimension is designed in consideration of the positional deviation at the time of forming (step (III)). That is, the pattern dimension is designed such that the insulating film covers both ends of the pair of device electrodes in the column direction. At this time, it is desirable that the length of the pair of device electrodes in the column direction is designed to be 60 μm or more longer than the length of the pair of device electrodes not covered with the insulating film in the column direction.

Step (II): A conductive paste made of the above-mentioned conductive material used for the connection electrodes and the column-direction wiring is applied on the substrate of the above step (I) by a screen printing method, and then fired to form the conductive paste shown in FIG. As shown in (II), a pattern of connection electrodes (4) and column-direction wirings (5) is formed.

Step (III): An insulating paste (for example, glass paste) is applied by a screen printing method according to the pattern size designed in the step (I), and then baked to form a pattern of a band-shaped insulating film (6). (Fig. 4
(III)) is formed. A contact hole (7) is opened in this insulating film (6) so as to communicate with the connection electrode (4).

Step (IV): On the above-mentioned insulating film, a conductive paste made of the above-mentioned conductive material used for the row wiring is printed by a screen printing method, followed by firing, and as shown in FIG. 4 (IV). The row wiring (8) is formed as shown. The row-direction wiring (8) is formed so that the connection electrode (4) can be energized through the contact hole (7).

Step (V): An electron emitting portion forming thin film made of the above material is formed on the entire surface of the substrate formed in the step (IV). Next, as shown in FIG. 4 (V), the thin film for forming the electron emitting portion is patterned by the photolithography method, and the electron emitting portion (3) is formed thereon.
At this time, it is desirable that the electron emission part forming thin film is formed over the entire space between the pair of device electrodes. The electron source substrate of the present invention is manufactured as described above.

Further, the electron source substrate manufactured in this manner has a face plate arranged on the top thereof and is installed in a vacuum envelope. FIG. 3 shows B of the electron source substrate of FIG.
The -B line sectional view and the sectional view of the face plate combined with the upper part of this electron source substrate are shown. The face plate has a phosphor layer (10) and a metal back layer (11) laminated on the surface of a glass substrate (9).

In this vacuum envelope, a voltage is applied between the element electrodes (2) through the row-direction wirings (8) and the column-direction wirings (5) capable of energizing the connection electrodes, and the upper metal back layer ( A voltage is applied to 11) with this as a positive potential. By this operation, electrons are emitted from the electron emitting portion (3) between the pair of device electrodes (2). The emitted electrons pass through the metal back layer (11) and are applied to the fluorescent layer (10) to generate fluorescence, and an image is formed. As described above, the electron source substrate of the present invention is applied as a light emitting element or a flat panel display in an image forming apparatus.

[0036]

EXAMPLES The present invention will now be further described by way of examples with reference to FIGS. 3 and 4, but the present invention is not limited thereto.

Example 1 Step (I): A substrate (1) made of soda lime glass was prepared,
Washed well. A metal thin film was formed on the surface of this substrate (1) by a sputter deposition method. Then, a device electrode (2) was formed by a photolithographic etching method as shown in FIG. The device electrode (2) is composed of a Ti thin film having a thickness of 50 nm and a Ni thin film having a thickness of 1000 nm. The distance between the pair of device electrodes is 2 μm, and the length of the device electrodes in the column direction is 26 μm.
The length was 0 μm and the length in the row direction was 300 μm. At this time, as a pattern dimension, on the completed electron source substrate, the length in the column direction of the pair of device electrodes not covered with the insulating film is 200.
A pattern was designed such that regions of 30 μm from both ends of the pair of device electrodes (2) in the column direction overlap with the insulating film (6) so as to be μm. That is, in this pattern, the length in the column direction of the pair of device electrodes in the completed electron source substrate shape is 60 μm longer than the length in the column direction of the pair of device electrodes not covered with the insulating film.

Step (II): Ag paste ink is applied on the substrate of the step (I) by screen printing, and as shown in FIG. 4 (II), the connection electrodes (4) and the column-direction wirings (5) are formed. A pattern was formed. It was then fired.

Step (III): A paste containing glass as a main component is applied by a screen printing method according to the pattern dimension designed in the step (I), and then baked to form a pattern () of a strip-shaped insulating film (6). (Fig. 4 (III))
Was formed. A contact hole (7) was opened in this insulating film (6) so as to reach the connection electrode (4). The insulating film (6) had a thickness of 15 μm and a length in the column direction of 400 μm. The positional deviation of the insulating film (6) in the column direction from the designed pattern dimension was 20 μm.

Step (IV): Ag paste is printed on the surface of the insulating film (6) by a screen printing method,
Then, firing was performed to form row wirings (8) as shown in FIG. The row-direction wiring (8) was made to be able to conduct electricity to the connection electrode (4) through the contact hole (7). The row-direction wiring (8) has a thickness of 20 μm,
The length in the column direction was 300 μm.

Step (V): An electron emitting portion forming thin film made of Pd particles having a thickness of about 200 angstroms is formed on the entire surface of the substrate formed in step (IV) by applying and baking an organometallic solution. did. Next, the thin film was patterned by photolithography as shown in FIG. 4 (V), and an electron emitting portion (3) was formed on the thin film. At this time, the electron emission portion forming thin film was formed over the entire area between the pair of device electrodes.

By the above process, 10 column-direction wirings (5) and 10 row-direction wirings (8) are formed, respectively.
An electron source substrate of the present invention was prepared in which 00 surface conduction electron-emitting device units were arranged in a matrix. At this time, the pitch of the element array was made to be 600 μm for both the matrix. In this electron source substrate, the position of the insulating film (6) was displaced in the step (III), but the length of the electron emitting portion (3) was not changed (200 μm as designed).

Next, as shown in FIG. 3, the above-mentioned electron source substrate was assembled so as to face the face plate at intervals of 5 mm, and was installed in a vacuum envelope. The glass substrate (9) of the face plate was made of soda lime glass. The phosphor layer (10) was formed by mixing a photosensitive resin with a phosphor to form a slurry, coating the slurry on the glass substrate (9), drying the slurry, and then patterning the slurry by photolithography. The metal back layer (11) is formed by using the phosphor layer (1
After the filming treatment was performed on the surface of (0), an Al thin film having a thickness of about 300 angstrom was formed by vacuum vapor deposition, and then the film was burned to burn off the film layer.

Example 2 The substrate (1) was 40 cm square (the length of one side was 40 c).
m squares), and 350 surface conduction electron-emitting device units are arranged in the matrix direction (a total of 122500 matrixes).
An electron source substrate similar to that of Example 1 was prepared except that the number of the above was set. This electron source substrate was combined with a face plate in the same manner as in Example 1 and placed in a vacuum envelope.

For the face plate, the phosphor (2
The same one as in Example 1 was used except that 2) was separately painted in each color of R, G and B.

Example 3 An electron source substrate was manufactured in the same manner as in Example 1 except for the following description. The length in the column direction of the device electrode (2) is 500 μm,
The length in the row direction was 250 μm. As a pattern dimension at this time, on the completed electron source substrate, the pair of device electrodes (2) are arranged in the column direction such that the length of the pair of device electrodes not covered with the insulating film in the column direction is 440 μm. A pattern was designed in which regions of 30 μm from both ends overlap the insulating film (6). That is, in this pattern, the length in the column direction of the pair of device electrodes in the completed electron source substrate shape is 60 μm longer than the length in the column direction of the pair of device electrodes not covered with the insulating film.

Further, the substrate (1) was set to a size of 40 cm square, the element array pitch of the electron-emitting devices was set to 840 μm, and 350 surface-conduction electron-emitting device units were arranged in the matrix direction (a total of 122500 matrix) ) I placed it.

The above electron source substrate was combined with a face plate in the same manner as in Example 1 and placed in a vacuum envelope.

Regarding the face plate, the phosphor (2
The same one as in Example 1 was used except that 2) was separately painted in each color of R, G and B.

(Evaluation Method and Evaluation Results) A predetermined voltage was applied to the column-direction wiring (5) and the row-direction wiring (8) of the electron source substrate of each of the above-mentioned examples. Then, using the metal back layer (11) of the face plate as an anode electrode,
An electron extraction voltage of 3 kV was applied to this. When the voltage applied to the column-direction wiring (5) and the row-direction wiring (8) was raised to 14 V, electrons were emitted from the electron emitting portion (3). The amount of emitted electrons was adjusted by the applied voltage, and the phosphor layer (10) was arbitrarily made to emit light to form an image. The image was uniform on any of the electron source substrates of Examples 1 to 3, and there was no decrease in image brightness or uneven brightness.

[0051]

As is apparent from the above description, according to the present invention, even if a positional deviation occurs during the formation of the insulating film on the electron source substrate, the pair of device electrodes not covered with the insulating film are arranged in the column direction. Since the length is constant and the length of the electron emitting portion formed between the device electrodes is also constant, it is possible to suppress a decrease in brightness and uneven brightness. Furthermore, since the electron source substrate is manufactured by the printing method, a large-screen image forming apparatus can be manufactured at low cost.

[Brief description of drawings]

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

2A is a cross-sectional view taken along the line AA in FIG. 1, and FIG. 2B is a cross-sectional view taken along the line AA in FIG. 1 in the case where misalignment occurs during the formation of an insulating film.

3A is a cross-sectional view of a face plate combined with an upper portion of an electron source substrate, and FIG. 3B is a cross-sectional view taken along line BB in FIG.

FIG. 4 is a plan view showing a manufacturing process of the electron source substrate of the present invention.

5A is a plan view of a conventional surface conduction electron-emitting device, and FIG. 5B is a cross-sectional view taken along the line CC in FIG. 5A.

FIG. 6A is a plan view of a conventional surface conduction electron-emitting device, and FIG. 6B is a sectional view taken along line DD in FIG.

FIG. 7 is a plan view of a conventional electron source substrate including the surface conduction electron-emitting device of FIG.

8A is a cross-sectional view taken along the line FF in FIG. 7, and FIG. 8B is a cross-sectional view taken along the line FF in FIG. 7 in the case where misalignment occurs during formation of an insulating film.

[Explanation of symbols]

 1 Substrate 2 Element Electrode 3 Electron Emission Section 4 Connection Electrode 5 Column Direction Wiring 6 Insulation Film 7 Contact Hole 8 Row Direction Wiring 9 Glass Substrate 10 Phosphor Layer 11 Metal Back Layer 12 Thin Film for Electron Emission Section Formation

Claims (3)

[Claims] 1. In an image forming apparatus including an electron source substrate on which surface conduction electron-emitting devices are arranged, an insulating film is formed so as to cover both ends of a pair of device electrodes in the column direction. A characteristic image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the length in the column direction of the pair of element electrodes is 60 μm or more longer than the length in the column direction of the pair of element electrodes not covered with the insulating film. 3. The method of manufacturing an image forming apparatus according to claim 1, wherein the wiring and the insulating film on the electron source substrate are formed by a screen printing method.