JP3135813B2 - Image forming apparatus and method of manufacturing the same - Google Patents

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 method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as a flat type image forming apparatus, a simple matrix liquid crystal display (LCD), a thin film transistor liquid crystal display (TFT / LCD), a plasma display (PDP), a low-speed electron beam fluorescent display (VFD) and the like have been known. 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 using an electron-emitting device. As this electron-emitting device, a surface conduction electron-emitting device is generally known (MI Elins).
on, Radio Eng. Electron Phys
s. , 10, (1965)). This electron-emitting device utilizes the phenomenon that 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 a thin film of a 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.I. G. FIG. Fonstad, IEEE Trans.
ED Conf. , 519 (1975)), carbon thin film (Hisashi Araki et al., Vacuum, 26, 1, 22 (198)
3)) etc. have been reported.

FIG. 5 shows a typical example of a surface conduction electron-emitting device. The structure of this electron-emitting device is the same as that of the above-mentioned M.E. Har
According to twell, 1 is an insulating substrate, 12 is a thin film for forming an electron emitting portion, and 3 is an electron emitting portion. The formation of the electron-emitting-portion-forming thin film (12) is performed by forming an H-shaped metal oxide thin film on the substrate (1) by sputtering. Next, an electron emission portion (3) is formed by an energization process called forming. Forming is a process in which a voltage is applied to both ends of the thin film for forming an electron emission portion (12), and the thin film (12) for forming an electron emission portion is locally broken, deformed, or altered, and an electron having a high electrical resistance is formed. Forming the discharge part (3). In some cases, electrons are emitted from the vicinity of a crack in the thin film (12) for forming an electron emission portion.

On the other hand, the present applicant has proposed a thin film (12) for forming an electron emitting portion, comprising an electron emitting material in which fine particles are dispersed and arranged.
Was developed between a pair of device electrodes to develop a new surface conduction electron-emitting device, and disclosed the technology (US Pat. No. 5,066,883). This electron-emitting device
Since the electron emission position can be controlled more precisely than the above-mentioned conventional one, the electron emission elements can be arranged with higher accuracy. FIG. 6 shows a typical example of this electron-emitting device. FIG.
In the figure, 1 is an insulating substrate, 2 is an element electrode for electrical connection, 12 is a thin film for forming an electron emitting portion made of an electron emitting material in which fine particles are dispersed and arranged, and 3 is an electron emitting portion.

[0007] A large number of the above surface conduction electron-emitting devices are formed on a substrate to produce an electron source substrate. This electron source substrate is combined with a plate having a phosphor and then placed in a vacuum envelope to form an image forming apparatus. In the vacuum envelope, electrons are emitted from the electron source substrate, and the electrons are irradiated on the phosphor of the plate.

The present applicant is studying the fabrication of an electron source substrate using the above-mentioned surface conduction electron-emitting device. FIG. 7 shows an example of the electron source substrate. FIG. 7 shows a part of an electron source substrate including two electron emitting elements in a row direction and two electron emitting elements in a column direction (a total of three electron emitting elements) among a large number of electron emitting elements formed in a matrix direction. It 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 are required, resulting in high cost. Therefore, when manufacturing a large-area image forming apparatus, it is desirable to perform the printing by 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 an electron emitting element is formed on a substrate to manufacture an electron source substrate. In particular, in FIGS. 7 and 8, problems occur in the pattern dimensional accuracy and the alignment accuracy between the element 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 (P ₁ = Q). As shown in FIG. 8B, the two insulating films (6) are displaced. As a result, the length in the column direction of the pair of device electrodes not covered with the insulating film is reduced, and the length in the column direction of the electron emission portion formed between the device electrodes is reduced (P ₁ > P _2). = P ₁ -R _1). As a result, the luminance is reduced or the luminance unevenness occurs. In FIG. 8, Q is the length of the element electrode (2) in the column direction, and P ₁ and P ₂
Is the length in the column direction of the device electrode not covered with the insulating film, R
Reference numeral ₁ denotes the length in the column direction of the device electrode covered by the displacement of the insulating film (6).

Accordingly, an object of the present invention is to make the length of the electron-emitting portion between the pair of element electrodes constant even when a positional shift occurs during the formation of the insulating film on the electron source substrate, so that the brightness of the image does not decrease. An object of the present invention is to provide an image forming apparatus with less luminance unevenness. Another object of the present invention is to provide a large-screen image forming apparatus at low cost by manufacturing an electron source substrate by a printing method.

[0012]

SUMMARY OF THE INVENTION According to the present invention, a plurality of surface conduction electron-emitting devices are provided with a plurality of row wirings formed on a substrate and substantially insulated from the plurality of row wirings. One of a pair of device electrodes of the surface conduction electron-emitting device is electrically connected to the row-direction wire, and the other device electrode is connected to the column-direction wire formed in the vertical direction. In the electron source substrate electrically connected to the direction wiring,
The present invention relates to an electron source substrate, wherein an insulating film formed in a band shape under the row wiring for insulation is formed so as to cover both ends of the pair of element electrodes in the column direction. Further, the present invention relates to an image forming apparatus including the above-mentioned electron source substrate and a face plate provided with a phosphor layer facing the electron source substrate. Further, the present invention relates to a method of manufacturing an image forming apparatus provided with the above-mentioned electron source substrate, wherein the wiring and the insulating film on the electron source substrate are formed by a printing method. .

Hereinafter, the present invention will be described in detail.

FIG. 1 shows a plan view of the electron source substrate of the present invention (in the figure, the X-axis direction is a row direction and the Y-axis direction is a column direction). FIG. 1 shows that two or more electron-emitting devices formed in rows and columns on an insulating substrate (1) are arranged in a row direction.
2 shows a part of an electron source substrate including two element electrodes in a column direction (three in total in a matrix). FIG. 2 is a sectional view taken along 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 of a pair of device electrodes in the column direction. 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. Pattern misalignment in printing method is at most ±
Since it is about 30 μm, it is preferable that the length is 60 μm or more. By setting the length of the device electrode in this manner, as shown in FIG. 2B, even if a displacement (R ₂ ) occurs during the formation of the insulating film, the column of the device electrode not covered with the insulating film The length (P ₂ ) in the direction is constant (P ₂ = P ₁ ). Therefore, when the electron-emitting-portion-forming thin film (12) is formed entirely between the pair of device electrodes not covered with the insulating film (FIG. 1).
Reference), the length of the electron-emitting portion (3) formed on the thin film (12) is also constant irrespective of the displacement of the insulating film, so that a decrease in luminance is suppressed and luminance unevenness is reduced.

The upper limit of the above-mentioned length of the element electrode is smaller than the length of the pixel pitch (see FIG. 4), and is actually about 50 μm shorter than the pixel pitch due to the printing resolution.

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

The thickness of the electron-emitting-portion-forming thin film (12) formed between the pair of device electrodes is suitably several tens to several thousand angstroms.

The connection electrode (4) and the column wiring (5) are connected to the device electrode (2), respectively. The thickness of these connection electrodes and column direction wirings is suitably several μm to several tens μm. The length of the connection electrode in the row direction is suitably several tens to several hundreds μm, and the length of the connection electrode in the column direction is suitably several hundred μm. The appropriate length of the column wiring in the row direction is 100 to 300 μm. The length of the column 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 with the column wiring (5). An appropriate thickness of the 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 suitably 200 to 600 μm.

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

As a material of the substrate, an insulating material is used, for example, quartz glass, glass with a reduced content of impurities such as Na, blue plate glass, SiO 2 by sputtering or the like.
Blue-sheet glass laminated with ₂ , ceramics such as alumina, and the like.

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

The material of the device electrode, the connection electrode, the row direction wiring and the column direction wiring 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 alloys thereof;
_{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 an 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 such as _{6 · CeB 6 · YB 4 ·} GdB 4, TiC · Z
Carbides such as rC / HfC / TaC / SiC / WC, Ti
Nitrides such as N / ZrN / HfN, semiconductors such as Si / Ge, carbon, and the like.

The thin film for forming the electron emitting portion is composed of a fine particle film of the above-mentioned material. A fine particle film is a film in which a plurality of fine particles are aggregated in a film shape. The fine structure is such that the fine particles are adjacent to each other or overlap with each other (including an island shape) in addition to the state in which the fine particles are individually dispersed and arranged. It has the structure of

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

Next, a method of manufacturing an electron source substrate according to the present invention will be described.
This will be described with reference to FIGS. FIG. 4 shows a case where a total of nine surface conduction electron-emitting device units are arranged in three rows and three columns.

Step (I): A conductive thin film made of the conductive material used for the device electrode is formed on the surface of the well-cleaned substrate (1). This substrate is finely processed by a photolithographic method to form a pattern of an element electrode (2) as shown in FIG. At this time, the insulating film (6)
The pattern size is designed in consideration of the positional deviation at the time of forming (step (III)). That is, the pattern dimensions are designed so that the insulating film covers both ends of the pair of element electrodes in the column direction. At this time, it is desirable that the length of the pair of element electrodes in the column direction is designed to be 60 μm or more longer than the length of the pair of element 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-directional wiring is applied on the substrate of the above-mentioned step (I) by a screen printing method, and then baked. As shown in (II), a pattern of the connection electrode (4) and the column wiring (5) is formed.

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

Step (IV): A conductive paste made of the conductive material used for row-directional wiring is printed on the insulating film by a screen printing method, and then baked, as shown in FIG. As shown, a row wiring (8) is formed. The row wiring (8) is formed so as to be able to conduct electricity to the connection electrode (4) through the contact hole (7).

Step (V): A thin film for forming an electron emission portion made of the above-mentioned material is formed on the entire surface of the substrate formed in step (IV). Next, as shown in FIG. 4 (V), the electron-emitting portion forming thin film is patterned by photolithography to form an electron-emitting portion (3).
At this time, it is desirable that the thin film for forming an electron-emitting portion is formed entirely between the pair of device electrodes. As described above, the electron source substrate of the present invention is manufactured.

Further, the electron source substrate manufactured as described above has a face plate disposed thereon, and is set in a vacuum envelope. FIG. 3 shows B of the electron source substrate of FIG.
FIG. 2B shows a cross-sectional view taken along line B and a cross-sectional view of a face plate combined with the upper portion of the electron source substrate. The face plate has a phosphor layer (10) and a metal back layer (11) laminated on a surface of a glass substrate (9).

In this vacuum envelope, a voltage is applied between the device electrodes (2) through the row-direction wiring (8) and the column-direction wiring (5) that can supply current to the connection electrodes, and the upper metal back layer ( A voltage is applied to 11) using 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 irradiate the fluorescent layer (10) through the metal back layer (11) to generate fluorescent light, thereby forming an image. As described above, the electron source substrate of the present invention is applied as a light emitting element or a flat display device in an image forming apparatus.

[0036]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be further described below with reference to the embodiments shown in FIGS. 3 and 4. However, the present invention is not limited to these embodiments.

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

Step (II): Ag paste ink is applied on the substrate of the above step (I) by a screen printing method, and as shown in FIG. 4 (II), the connection electrode (4) and the column-directional wiring (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 in accordance with the pattern dimensions designed in the step (I), and then baked to obtain a pattern of the strip-shaped insulating film (6). (Fig. 4 (III))
Was formed. A contact hole (7) was opened in the insulating film (6) so as to communicate with the connection electrode (4). The thickness of the insulating film (6) was 15 μm, and the length in the column direction was 400 μm. The positional deviation of the insulating film (6) in the column direction with respect to the designed pattern dimension was 20 μm.

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

Step (V): By applying and baking an organic metal solution, a thin film for forming an electron emitting portion composed of Pd fine particles having a thickness of about 200 Å is formed on the entire surface of the substrate formed in the step (IV). did. Next, the thin film was patterned by a photolithographic method as shown in FIG. 4 (V), and an electron emitting portion (3) was formed thereon. At this time, the thin film for forming an electron emission portion was formed entirely between the pair of device electrodes.

According to the above steps, ten column-directional wirings (5) and ten row-directional wirings (8) are formed.
An electron source substrate of the present invention in which 00 surface conduction electron-emitting devices were arranged in a matrix was manufactured. At this time, the device was manufactured such that the pitch of the element array was 600 μm for both the matrix. In the electron source substrate, the position of the insulating film (6) was displaced in the step (III), but the length of the electron emission portion (3) was not changed (200 μm as designed).

Next, as shown in FIG. 3, the above-mentioned electron source substrate was combined with the face plate facing the face plate at an interval of 5 mm, and set in a vacuum envelope. The glass substrate (9) of the face plate was made of blue plate glass. The phosphor layer (10) was formed by mixing a phosphor with a photosensitive resin to form a slurry, applying the slurry to a glass substrate (9), drying the slurry, and then performing patterning by photolithography. The formation of the metal back layer (11) is performed by using the phosphor layer (1).
After performing a filming process on the surface of 0), an Al thin film having a thickness of about 300 Å was formed by vacuum evaporation, and then fired to burn off the film layer, thereby forming a film.

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

As for the face plate, the phosphor (2
The same thing as in Example 1 was used except that 2) was separately applied by R, G and B colors.

Example 3 An electron source substrate was manufactured in the same manner as in Example 1 except for the following. The length of the element electrode (2) in the column direction is 500 μm,
The length in the row direction was 250 μm. At this time, the pattern dimension of the pair of device electrodes (2) in the column direction is set so that the length in the column direction of the pair of device electrodes not covered with the insulating film is 440 μm on the completed electron source substrate. A pattern in which a region of 30 μm from each end overlaps with the insulating film (6) was designed. That is, in this pattern, in the completed electron source substrate, the length of the pair of device electrodes in the column direction is longer than the length of the pair of device electrodes not covered with the insulating film by 60 μm.

The size of the substrate (1) is 40 cm square, the pitch of the element array of the electron-emitting devices is set to 840 μm, and 350 surface conduction electron-emitting units are arranged in the matrix direction (total of 12,500 matrixes). ) Placed.

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

Regarding the face plate, the phosphor (2
The same thing as in Example 1 was used except that 2) was separately applied by R, G and B colors.

(Evaluation Method and Evaluation Results) A predetermined voltage was applied to the column wiring (5) and the row wiring (8) of the electron source substrate of each of the above embodiments. 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 wiring (5) and the row wiring (8) was increased 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 emitted to form an image. In each of the electron source substrates of Examples 1 to 3, the image was uniform, and no reduction in the luminance of the image and no uneven luminance occurred.

[0051]

As is apparent from the above description, according to the present invention, even if a position shift occurs during the formation of the insulating film on the electron source substrate, the pair of device electrodes not covered by the insulating film in the column direction is not covered by the insulating film. 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 luminance and luminance unevenness. Further, since the electron source substrate is manufactured by a printing method, a large-screen image forming apparatus can be manufactured at low cost.

[Brief description of the drawings]

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

FIG. 2A is a cross-sectional view taken along line AA in FIG. 1, and FIG. 2B is a cross-sectional view taken along line AA in FIG. 1 when a positional shift occurs during 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.

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

FIG. 6A is a plan view of a conventional surface conduction electron-emitting device, and FIG. 6B is a cross-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 when a positional shift occurs during the formation of the insulating film.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Element electrode 3 Electron emission part 4 Connection electrode 5 Column wiring 6 Insulating film 7 Contact hole 8 Row wiring 9 Glass substrate 10 Phosphor layer 11 Metal back layer 12 Thin film for electron emission part formation

Claims (4)

(57) [Claims] 1. A plurality of row-direction wirings formed on a substrate and a plurality of columns formed in a substantially vertical direction and electrically insulated from the plurality of row-direction wirings. One of a pair of device electrodes of the surface conduction electron-emitting device is electrically connected to the row direction wiring,
In the electron source substrate in which one of the remaining element electrodes is electrically connected to the column-directional wiring, an insulating film formed in a strip shape under the row-directional wiring for insulation is formed of a column of the pair of element electrodes. An electron source substrate formed so as to cover both ends in the direction. 2. An image forming apparatus comprising: the electron source substrate according to claim 1; and a face plate provided with a phosphor layer facing the electron source substrate. 3. A method for manufacturing an image forming apparatus comprising the electron source substrate according to claim 1, wherein the wiring and the insulating film on the electron source substrate are formed by a printing method. Manufacturing method. 4. The method according to claim 3, wherein the printing method is a screen printing method.