JP2003291404A - Organic el array exposure head and imaging apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To condense onto an image carrier such as a photoreceptor, a luminous flux from each element by full resolving power and contrast by reducing crosstalks of an organic EL array exposure head. <P>SOLUTION: The organic EL array exposure head has an array of organic EL elements 4 arranged at least in the shape of one array of pixels on a long substrate 6. A diaphragm 12 is set at the light emitting side of the array of organic EL elements 4, which has an optical hole 14 formed for obstructing mixing of light emitted from a light emitting part of the organic EL element adjacent to a collecting position of light emitted from a light emitting part of each organic EL element. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic EL array exposure head and an image forming apparatus using the same, and in particular,
The present invention relates to an organic EL array exposure head capable of preventing crosstalk between pixels and an image forming apparatus using the same.

[0002]

2. Description of the Related Art Conventionally, various proposals have been made for using an organic EL array as an exposure head for an image forming apparatus.
The related items are as follows.

In Japanese Unexamined Patent Publication No. 10-55890, an organic EL array is collectively manufactured on an insulating substrate such as glass,
A separate driver IC is combined and a condensing rod lens array is used to form an image of the light emitting portion of the organic EL array on the photosensitive drum.

In Japanese Patent Laid-Open No. 11-198433,
The one-chip organic EL array having a plurality of rows is used, and the optical system for forming an image of the light emitting portion on the photosensitive drum is unknown. The EL layer of the organic EL array is deposited by vapor deposition.

In Japanese Patent Laid-Open No. 2000-77188, a microlens is formed on the upper surface of the substrate by an in-exchange method,
A microlens is formed on the back surface of the substrate by a method using a photoresist or a replica method, and an organic EL array having a resonator structure is deposited by vapor deposition in alignment with the microlens.

Japanese Unexamined Patent Publication No. 10-12377 relates to a method for manufacturing an active matrix type organic EL display body, in which an organic light emitting layer is formed on a glass substrate having a thin film transistor by an ink jet method.

In Japanese Patent Laid-Open No. 2000-323276,
The hole injecting layer and the organic light emitting layer of the organic EL element are formed by providing partition walls and applying them by an inkjet method.

In Japanese Patent Laid-Open No. 2001-18441, a printer is constructed by forming a light emitting layer and a TFT layer for controlling the light emission inside the photosensitive drum.

[0009]

In the above prior art, when the organic EL array is used in the exposure head of a printer such as an electrophotographic system, the light flux from the light emitting portion of the organic EL array is condensed on the photosensitive drum. When a condensing rod lens array is used for the above, the optical path length becomes long and the size becomes large, and since the condensing rod lens is not arranged one-to-one with respect to each light emitting part, periodic light amount unevenness occurs. Further, the cost of the condensing rod lens is inevitable because of its advanced manufacturing method.

In the case of using a microlens array, each microlens is arranged in a one-to-one correspondence with each light emitting portion, but it is not a microlens corresponding to the light emitting portion but a microlens not corresponding to the adjacent one or the like. Crosstalk is likely to occur at pixel positions that do not correspond to each other, which causes a problem such as a reduction in resolution.

The present invention has been made in view of the above problems of the prior art, and an object thereof is to cross an organic EL array exposure head in which microlenses are arranged corresponding to individual elements of the organic EL array. Reduce talk,
It is an object of the present invention to provide a small-sized exposure head configured to focus the light flux from each element on an image carrier such as a photoconductor with sufficient resolution and contrast, and an image forming apparatus using the same.

[0012]

An organic EL array exposure head of the present invention which achieves the above object, comprises:
An organic EL element that includes an array of at least one row of organic EL elements arranged in a pixel shape, and is adjacent to a light-emission side of the array of the organic EL elements at a light collecting position of light emitted from a light-emitting portion of each organic EL element. The partition wall is provided with an optical hole for blocking the mixture of the light emitted from the light emitting section.

In this case, it is desirable that a positive lens is arranged at each hole position of the partition wall.

Further, it is desirable that the substrate and the partition wall have substantially the same linear expansion coefficient.

Further, the partition wall may be any of those formed by punching holes in a metal plate, those formed by punching holes by resin molding, and the like.

The partition wall and the substrate may be integrally formed.

The height of the exit side surface of the partition wall may be higher or lower than that of the positive lens.

Further, it is desirable that the wall surface of the hole of the partition wall be light reflecting or light absorbing.

The positive lens can be made of resin. In that case, the positive lens may be formed in the hole of the partition wall by an ink jet method or formed by a molding method.

The positive lens may be made of glass.

The positive lens may be a ball lens.

The organic EL element may be one that emits emitted light to the anode side or one that emits emitted light to the cathode side.

Further, the organic EL element may be either a high molecular type or a low molecular type.

The organic EL element is a TF provided on the substrate.
It is desirable that light emission control be performed at T.

The present invention includes an image forming apparatus equipped with the above-described organic EL array exposure head as an exposure head for writing an image on an image carrier.
As an example, at least two or more image forming stations provided with a charging unit, an exposure head, a toner developing unit, and a transfer unit are provided around the image carrier, and a transfer medium passes through each station to form a color image. There is a tandem type color image forming apparatus for performing the above.

In the case of the image forming apparatus for developing with this toner developing means, when the work function of the material of the positive lens is Φ _L , the work function of the material of the partition wall is Φ _B , and the work function of the toner material is Φ _T , It is desirable to simultaneously satisfy the relationship of | Φ _T −Φ _L | ≦ 0.2 eV (1) | Φ _T −Φ _B | ≧ 0.5 eV (2).

In the present invention, the light emitting side of the array of organic EL elements is mixed with the light emitted from the light emitting portions of the organic EL elements adjacent to the condensing position of the light emitted from the light emitting portions of each organic EL element. Since the partition wall provided with an optical hole that blocks the light is disposed, crosstalk between adjacent pixels is reduced, and sufficient resolution and contrast can be obtained.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of an organic EL array exposure head of the present invention and an image forming apparatus using the same will be described below with reference to the drawings.

FIG. 1 is a schematic plan view of an embodiment of an organic EL array exposure head according to the present invention, and FIG. 2 is a sectional view of one pixel of the array along the line AA 'in FIG. Show.

Organic EL array exposure head 1 of this embodiment
Is an array in which two rows of arrays 2 and 2'are arranged in parallel with each other in a staggered pattern, and each array 2, 2'is composed of a large number of light emitting pixels 3 arranged in a straight line, Each pixel 3
Have the same structure, and the organic EL element 4 and the organic EL element 4
And a TFT 5 for controlling the emission of light.

FIG. 2 shows the organic EL element 4 and the TFT of one pixel 3.
5 shows a sectional view including 5 and 5. This organic EL element 4 is an example in which emitted light is emitted from the cathode side.

The organic EL element 4 is one in which electrons and holes are injected from the cathode 10 and the anode 7, respectively, and recombines to emit light, and an electron transporting light emitting layer 9 and a hole injecting layer 8 are laminated. It has a different structure.

There are two types of organic EL elements, one that takes out light from the cathode and the other that takes out light from the anode. Generally, the one that takes out light from the anode, that is, the substrate side (the example described later) is used. It is largely due to manufacturing restrictions.
Since the light is emitted from the substrate side, the substrate is limited to a transparent member such as glass, and the drive circuit is a TFT that can be formed on the glass.

On the other hand, in this embodiment, light is extracted from the cathode side, and the cathode 10 is light transmissive. On the other hand, the anode 7
Has the effect of increasing the amount of radiation to the cathode 10 side by making it not light transmissive but reflective.

This organic EL array exposure head 1 includes a substrate 6 made of glass, silicon or the like, an anode 7 made of ITO or an alloy of magnesium and silver, aluminum or the like, a hole injection layer 8, a light emitting layer 9, ITO or light. The cathode 10, which is a metal electrode thin enough to allow the light to pass through, the adhesive layer 11 made of a transparent resin, and the microlens 1 also serving as a condensing element and a sealing member for preventing the light emitting layer 9 from deteriorating due to contact with moisture.
As shown in FIG. 1, for example, one light emitting pixel 3 including a partition wall 12 disposed between the microlenses 13 and the microlenses 13 is arranged in a two-row array 2 or 2 ′. .

As will be described later, for example, in the case of being used as an exposure head of an electrophotographic color image forming apparatus, the photoconductor is opposed to the microlens 13, and each microlens 13 acts to emit light. Pixel 3
The emitted light from is collected in an array on the photoconductor.

Organic EL array exposure head 1 of this embodiment
As a basic manufacturing method and structure of the organic EL device, an organic EL device including organic EL elements 4 and TFTs 5 arranged in an array on a substrate 6 is used.
The L array and the array of microlenses 13 that collect the emitted light of the organic EL element 4 are manufactured separately, and are optically and mechanically coupled via the adhesive layer 11. . The manufacturing method of the organic EL element 4 may be any known general method, and the films 7, 8, 9, and 10 are formed on the substrate 6 by a vacuum deposition method, a casting method, or the like. Alternatively, it can be formed by an inkjet method as described in JP-A-10-12377. An ultraviolet curable resin is most easily used as the microlenses 13 and the adhesive layer 11, but the present invention is not limited to this as long as it has sufficient transmittance for the emission wavelength and is compatible with the manufacturing process. In particular, since the material of the light emitting layer 9 does not like ultraviolet irradiation, it may be considered that a resin such as thermosetting resin is preferable.

Explaining one example of the method of manufacturing the organic EL array, the TFT 5 is first manufactured on the substrate 6. Although various methods of manufacturing the TFT 5 are known. For example, a silicon oxide film is first deposited on the substrate 6, and then an amorphous silicon film is further deposited. Next, the amorphous silicon film is irradiated with excimer laser light to be crystallized to form a polysilicon film to be a channel. After patterning this polysilicon film, a gate insulating film is deposited and a gate electrode made of tantalum nitride is further formed. continue,
The source / drain portion of the N-channel TFT is formed by ion implantation of phosphorus, and the source / drain portion of the P-channel TFT is formed by ion implantation of boron. After activating the ion-implanted impurities, depositing a first interlayer insulating film,
The opening of the first contact hole, the formation of the source line, the deposition of the second interlayer insulating film, the opening of the second contact hole, and the formation of the metal pixel electrode are sequentially performed to complete the array of TFTs 5 (for example, 8th electronic display).・ Forum (20
See 01.4.18) “Polymer type organic EL display”. ). Here, the metal pixel electrode is the organic EL element 4
Which also serves as the reflection layer of the organic EL element 4 and is formed of a metal thin film electrode of Mg, Ag, Al, Li or the like.

Then, the ink composition for the hole injection layer is discharged from the head of the ink jet type printing apparatus,
Patterning application is performed on the anode 7 of each pixel. After application
The solvent is removed and heat treatment is performed to form the hole injection layer 8.

Here, the ink jet method referred to in the present invention is a piezo jet method in which the mechanical energy of a piezoelectric element or the like is used to eject an ink composition, and the thermal energy of a heater is used to generate bubbles, and the bubbles are generated. Any of the thermal methods for ejecting the ink composition based on the generation of the ink (Fine Imaging and Hard Copy), ed.
Published 9.1.7 (Corona Inc.) p. 43). Figure 3
An example of the structure of a piezo jet type head is shown in FIG. The inkjet head 21 includes, for example, a stainless nozzle plate 22 and a vibration plate 23, both of which are joined via a partition member (reservoir plate) 24.
A plurality of ink chambers 25 and a liquid pool (not shown) are formed by the partition member 24 between the nozzle plate 22 and the vibration plate 23. The interiors of the ink chamber 25 and the liquid pool are filled with the ink composition, and the ink chamber 25 and the liquid pool communicate with each other through the supply port. Further, the nozzle plate 22 is provided with nozzle holes 26 for ejecting the ink composition from the ink chamber 25 in a jet shape. On the other hand, the ink jet head 21 is provided with an ink introduction hole for supplying the ink composition to the liquid pool. A piezoelectric element 28 is bonded to the surface of the vibrating plate 23 opposite to the surface facing the ink chamber 25 so as to correspond to the position of the ink chamber 25. The piezoelectric element 28 is located between the pair of electrodes 29, and when energized, the piezoelectric element 28 bends so as to project outward. This allows the ink chamber 25
Increases the volume of. Therefore, the ink composition corresponding to the increased volume flows into the ink chamber 25 from the liquid reservoir through the supply port. Next, when the energization of the piezoelectric element 28 is released, both the piezoelectric element 28 and the diaphragm 23 return to their original shapes. As a result, the space 25 also returns to the original volume, so that the pressure of the ink composition inside the ink chamber 25 rises and the nozzle hole 26
The ink composition is ejected toward the substrate provided with the partition walls 9.

After forming the hole injection layer 8 on the anode 7, the ink composition for the light emitting layer is discharged from the head of the ink jet printing apparatus, and the hole injection layer 8 of each pixel is subjected to patterning coating. After coating, the solvent is removed and heat treatment is performed to form the light emitting layer 9.

The order of the hole injection layer 8 and the light emitting layer 9 may be reversed. It is desirable to dispose a layer more resistant to moisture on the surface side (the side farther from the substrate 6).

The hole injection layer 8 and the light emitting layer 9 are formed by a known spin coating method, dipping method or vapor deposition method instead of being formed by applying the ink composition by the ink jet method as described above. You can also In particular, the inkjet method is suitable when the organic EL material is a polymer organic EL material, and the vapor deposition method is suitable when the organic EL material is a low molecular weight organic EL material.

Regarding the materials used for the light emitting layer 9 and the hole injection layer 8, high molecular weight organic EL materials are described in, for example, JP-A-10-12377, low molecular weight organic E.
As the L material, various materials known in, for example, JP-A No. 11-138899 can be used, and details thereof will be omitted.

After the hole injection layer 8 and the light emitting layer 9 are sequentially formed on the anode 7 of each pixel, a transparent electrode to be the cathode 10 of the organic EL element 4 is deposited on the entire surface of the substrate 6 by the vacuum deposition method. . The material of this transparent electrode is tin oxide film, IT
There are an O film, a complex oxide film of indium oxide and zinc oxide, and the like, and besides the vacuum deposition method, a photolithography method, a sputtering method, a pyrosol method, or the like can be adopted.

In the microlens array in which the partition walls 12 are arranged between the microlenses 13 on the organic EL array thus manufactured, each microlens 13 corresponds to each organic EL element 4 in a one-to-one correspondence. In the aligned state, they are optically and mechanically coupled by the adhesive layer 11.

In the structure shown in FIG. 2, since the emitted light is emitted to the cathode 10 side, that is, the side opposite to the substrate 6,
The substrate 6 may be opaque, and the driving circuit does not need to be the TFT 5. A configuration in which the organic EL element 4 is laminated on a drive circuit formed by a general silicon process is also possible.

Now, the partition wall 12 will be described. When a voltage is applied between the cathode 10 and the anode 7 by controlling the TFT 5, the light emitting layer 9 emits light. The emitted light is isotropically emitted from the light emitting layer 9 in all directions, but if the anode 7 is non-light transmissive, it passes through the cathode 10 and is mainly transmitted through the cathode 10.
Is emitted above. A component having a small angle with respect to the normal line of the light emitting layer 9 reaches the microlens 13 as it is, is emitted directly through the microlens 13, and is condensed at a predetermined position. On the other hand, a component having a large angle with respect to the normal line of the light emitting layer 9 is the microlens 1
Heading for the partition 12 between the three. When the partition wall 12 is formed of, for example, a metal plate having holes 14 for holding a large number of microlenses 13 arranged in an array, the holes 14 of the partition wall 12 are used.
Since the wall surface of is a light-reflecting property, it is reflected once or is multiple-reflected between the wall surfaces of the holes 14 of the partition wall 12, reaches the microlens 13 and is emitted, and at least a part thereof is The light directly condensed through the microlens 13 is condensed near the condensing position. Therefore, in this case, a component having a large angle with respect to the normal line of the light emitting layer 9 is also used as light that is condensed in an array, so that the efficiency is high, the power is low, and the life is long (the biggest problem in the organic EL). .) Exposure head.

When the partition wall 12 is made of a light-absorbing material such as black resin or a resin in which carbon powder is dispersed, a component having a large angle with respect to the normal line of the light emitting layer 9 is formed on the wall surface of the hole 14. Since it is absorbed, the component having the large angle can be more surely eliminated.

In both cases where the partition wall 12 is light-reflective or light-absorbing, compared with the case where the partition wall 12 is not provided, overlapping with light emitted from an adjacent pixel adjacent to the photoconductor occurs (crosstalk occurs. ) The effect that the degree is significantly reduced is high.

In the above-described structure in which the emitted light is emitted from the cathode 10 side of the organic EL element 4 of FIG. 2, a sealing member (microlens 13) separates the organic EL element 4 from the outside.
Since it can be made thin, the amount of light extracted from the organic EL element 4 can be improved. In addition, the organic EL element 4
The distance between the light emitting portion and the microlens 13 or the partition wall 12 can be shortened, and crosstalk between pixels can be prevented more easily.

The partition wall 12 may be made of a metal plate having a large number of holes 14 formed in an array as described above, or a resin plate having a large number of holes 14 formed in an array by molding. However, in any case, it is desirable to use a substrate whose coefficient of linear expansion is substantially equal to that of the substrate 6. Then, even if the temperature changes, the light emitting point of the organic EL element 4 and the microlens 13 in the partition 12 do not shift, and the temperature stability of the condensing point array of the exposure head 1 becomes high. In addition, when the partition wall 12 is manufactured by resin molding, there is an advantage that the manufacturing is easy, and the cost and the weight are low.

In the above description, the organic EL array and the microlens array in which the partition walls 12 are arranged between the lenses are manufactured separately and bonded by the adhesive layer 11. However, the partition walls 12 are integrated with the substrate 6. You may comprise. For example, holes 14 having a certain depth for arranging the pixels 3 are formed in an array on the surface of the substrate 6, and the function of the partition 12 is provided between the holes 14, and the TFTs 5 and the organic EL elements are provided at the bottoms of the holes 14. 4 (anode 7, hole injection layer 8, light emitting layer 9 and cathode 10) are stacked to form an organic E
The microlens 13 is arranged on the L element 4. In this case, whether the substrate 6 itself is light-reflecting or light-absorbing,
When the substrate 6 is made of a transparent material such as glass, the substrate 6
For example, a light reflecting film or a light absorbing film may be applied so that the inner surface of the hole 14 formed on the surface becomes light reflecting or light absorbing. As described above, when the partition wall 12 is formed integrally with the substrate 6, there is an advantage that the positional accuracy of the light emitting portion of the organic EL element 4, the microlens 13, and the partition wall 12 is improved.

Further, the microlens 1 provided on the partition wall 12
Although various kinds of materials may be used for the ink jet printer 3, as shown in FIG. 4, an ink jet type printing apparatus is provided with a transparent ink composition for a microlens, for example, a UV curable resin monomer, in a hole 14 provided in the partition wall 12. 20 heads 21
It can be formed by discharging it from the substrate, performing patterning coating, curing after coating, and forming a convex microlens that bulges convexly on the upper surface of the hole 14. In this case, the radius of curvature of the convex surface of the microlens 13, that is, the focal length, is the ejection amount of the ink composition, the diameter of the hole 14, the surface tension of the transparent ink composition for microlenses, and the water repellency of the inner surface of the hole 14. Although it depends on the degree and the amount of shrinkage when the ink composition is cured, there are advantages that the lens surface precision is high and a microlens array can be easily manufactured without a mold. The member 15 arranged at the bottom of the hole 14 in FIG. 4 is a backing member and is removed after the ink composition is cured. However, when the partition wall 12 is formed integrally with the substrate 6, the member 15 is the substrate 6, and the TFT 5 and the organic EL element 4 disposed there.

Further, the microlenses 13 formed in the holes 14 of the partition wall 12 can be made of glass or transparent resin by a molding method (replica method). in this case,
The stability of the shape of the microlens 13 is high, and the degree of freedom of the shape is high.

Further, as the microlens 13, FIG.
A ball (spherical) lens 13 ′ made of glass or resin as shown in FIG. 5A or a hemispherical lens 13 ″ as shown in FIG. 5B may be used.
It may be dropped into the hole 14 and fixed with the adhesive 16.

By the way, regarding the height relationship between the lens surface of the microlens 13 arranged in the hole 14 of the partition wall 12 and the upper surface of the partition wall 12, as shown in FIGS. 2, 4 and 5 (a),
There are cases where the lens surface of the microlens 13 is made higher than the upper surface of the partition wall 12, and cases where the partition wall 12 is made higher than the lens surface of the microlens 13 as shown in FIG. 5B. In the latter case, the partition wall 12 serves as a protective member and can protect the microlens 13 from scratches and damages. In the former case, the microlens 13 can be easily manufactured by the inkjet method as shown in FIG.

Next, FIG. 6 shows an embodiment in which emitted light is emitted from the anode side of the organic EL element 4. Similar to FIG. 2, FIG. 6 is a cross-sectional view of one pixel of the array along the line AA ′ in FIG.

In this organic EL array exposure head 1, an organic EL element 4 is formed on a transparent substrate 6 such as glass, and an anode 7 made of a substantially transparent material such as ITO is formed in the same manner as in FIG.
The hole injection layer 8, the light emitting layer 9, the cathode 10 which is an electrode made of ITO, an alloy of magnesium and silver, aluminum or the like.
And the sealing member 18 for preventing the light emitting layer 9 from deteriorating due to exposure to moisture by the adhesive layer 17 is bonded thereon to produce an organic EL array.

The method for manufacturing the organic EL element 4 may be any known general method as in the case of FIG.
The films 8, 9, and 10 are formed on the substrate 6 by a vacuum deposition method, a casting method, or the like. Alternatively, Japanese Patent Laid-Open No. 10-1237
It can also be formed by an inkjet method as described in No. 7 and the like.

In this structure of the organic EL array thus manufactured, the microlens array in which the partition walls 12 are arranged between the microlenses 13 is provided on the substrate 6 side, as in the case of FIG. 13 is brought into an alignment state in which the organic EL elements 4 are in a one-to-one correspondence with each organic EL element 4 and is optically and mechanically coupled by the adhesive layer 11.

In the structure shown in FIG. 6, since the emitted light is emitted to the anode 7 side, that is, the substrate 6 side, the substrate 6 must be transparent, so that the driving circuit is the TFT 5
Need to be used.

Also in this structure, when a voltage is applied between the cathode 10 and the anode 7 by controlling the TFT 5, the light emitting layer 9 emits light. The emitted light is isotropically emitted from the light emitting layer 9 in all directions, but if the cathode 10 is non-light transmissive, it passes through the anode 7 and the substrate 6 and is mainly emitted downward in FIG. . A component having a small angle with respect to the normal line of the light emitting layer 9 reaches the microlens 13 as it is, is emitted directly through the microlens 13, and is condensed at a predetermined position. On the other hand, the component having a large angle with respect to the normal line of the light emitting layer 9 is the partition wall 12 between the microlenses 13.
Head to. When the hole 14 of the partition wall 12 is light reflective,
After single reflection or multiple reflection between the wall surfaces of the hole 14, the micro lens 13 is emitted and emitted, and at least a part thereof is in the vicinity of the condensing position of the light condensed directly through the micro lens 13. Focus on. Therefore, in this case, a component having a large angle with respect to the normal line of the light emitting layer 9 is also used as light that is condensed in an array, so that the efficiency is high, the power is low, and the life is long (the biggest problem in the organic EL). .) Exposure head. When the partition 12 is light-absorbing, the component having a large angle with respect to the normal line of the light emitting layer 9 is absorbed by the partition 12, and thus the component having a large angle can be more surely eliminated. Therefore, in any case, as compared with the case without the partition wall 12,
It is possible to obtain an effect of significantly reducing the degree of overlapping (crosstalk) with the light emitted from the adjacent pixel on the photoconductor.

The structure of FIG. 6 has a feature that the material selection and the manufacturing method are easy because it emits the emitted light to the anode 7 side of the transparent substrate 6 as in the conventional organic EL element. The microlens 13 and the partition 12 through the transparent substrate 6.
Since the emitted light is incident on the organic EL element 4, the distance between the light emitting portion of the organic EL element 4 and the microlens 13 or the partition wall 12 tends to be long, the amount of light extracted from the organic EL element 4 is reduced, and crosstalk between pixels may occur. It tends to increase.
To alleviate these problems, it is necessary to use a sufficiently thin substrate 6 or to grind the substrate 6 to reduce the thickness after the organic EL array is manufactured. Currently, a substrate having a thickness of about 0.3 mm can be used,
Further, a technique of making the thickness as thin as about 0.1 mm by polishing is becoming generally available. If the handling during the polishing process or the mechanical strength after becoming a product is insufficient, this can be avoided by leaving a portion having a frame-like thickness on the substrate 6.

In the case of the structure in which the emitted light is emitted to the anode 7 side in FIG. 6, the partition wall 12 and the microlens 13 can be applied in the same manner as in FIG.

The organic EL array exposure head 1 in which the partition walls are provided between the microlenses to reduce the crosstalk according to the present invention as described above is shown in the side view of FIG. The light flux emitted from each organic EL light-emitting section 4 is condensed on the surface S, which is separated by a predetermined distance L from, in the same arrangement pattern as the arrangement of the pixels 3 of the organic EL array exposure head 1. Therefore, the surface S is relatively moved in the direction orthogonal to the longitudinal direction of the organic EL array exposure head 1, and each organic E of the organic EL array exposure head 1 is moved.
By controlling the light emission of the L element 4 by the TFT 5, the surface S
A predetermined pattern can be recorded on it.

Therefore, in the present invention, the organic EL array exposure head 1 of the present invention as described above is used as an exposure head of an electrophotographic color image forming apparatus, for example. FIG. 8 is a tandem in which four similar organic EL array exposure heads 1K, 1C, 1M, and 1Y of the present invention are arranged at the exposure positions of four corresponding photosensitive drums 41K, 41C, 41M, and 41Y, respectively. FIG. 1 is a front view showing an overall schematic configuration of an example of a color image forming apparatus of a system. Figure 8
As shown in FIG. 5, this image forming apparatus is tensioned by a driving roller 51, a driven roller 52, and a tension roller 53 and stretched, and is circulated and driven in the direction of the arrow (counterclockwise direction) in the drawing. And four photoconductors 41K, 41 having a photoconductive layer on the outer peripheral surface as four image carriers disposed at a predetermined interval with respect to the intermediate transfer belt 50.
C, 41M and 41Y are arranged. K, C, M, and Y added after the symbols mean black, cyan, magenta, and yellow, respectively, and indicate that they are photoconductors for black, cyan, magenta, and yellow, respectively. The same applies to other members. The photoconductors 41K, 41C, 41M, and 41Y are rotationally driven in the arrow direction (clockwise direction) in the figure in synchronization with the driving of the intermediate transfer belt 50.
Around the periphery of M, Y, the photoconductor 41 (K, C,
Charging means (corona charger) 42 (K, C, M, Y) for uniformly charging the outer peripheral surface of (M, Y), and this charging means 42
The outer peripheral surface uniformly charged by (K, C, M, Y) is sequentially line-scanned in synchronization with the rotation of the photoconductor 41 (K, C, M, Y). Toner as a developer is applied to the electrostatic latent image formed by the EL array exposure head 1 (K, C, M, Y) and the organic EL array exposure head 1 (K, C, M, Y). A developing device 44 (K, C, M, Y) that forms a visible image (toner image), and an intermediate transfer that is a primary transfer target of the toner image developed by the developing device 44 (K, C, M, Y) A primary transfer roller 45 (K, C, M, Y) as a transfer means for sequentially transferring to the belt 50,
A cleaning device 46 (K, C, M, Y) as a cleaning unit that removes the toner remaining on the surface of the photoconductor 41 (K, C, M, Y) after being transferred.

Here, each organic EL array exposure head 1
(K, C, M, Y) are each organic EL as shown in FIG.
The microlens 13 having a predetermined focal length is formed by an inkjet method in the hole 14 of the partition wall 12 at a position corresponding to the light emitting portion of the element 4.
A predetermined distance L from the surface of (K, C, M, Y),
The organic EL array exposure head 1 (K, C, M, Y) is installed so that the array direction is along the generatrix of the photoconductor drum 41 (K, C, M, Y). Then, the emission energy peak wavelength of each organic EL array exposure head 1 (K, C, M, Y) and the sensitivity peak wavelength of the photoconductor 41 (K, C, M, Y) are set to substantially match. There is.

The developing device 44 (K, C, M, Y) uses, for example, a non-magnetic one-component toner as a developer,
The one-component developer is conveyed to the developing roller by, for example, a supply roller, the film thickness of the developer adhered to the surface of the developing roller is regulated by a regulating blade, and the developing roller is moved to the photoconductor 41 (K,
C, M, Y) to contact or press the photoconductor 41
The toner is developed as a toner image by attaching a developer according to the potential level of (K, C, M, Y).

The black, cyan, magenta, and yellow toner images formed by the four-color monochromatic toner image forming stations are transferred to the primary transfer rollers 45 (K, C, M, and
The primary transfer bias applied to Y) sequentially primary-transfers the toner images onto the intermediate transfer belt 50, and the toner images in full color are sequentially superposed on the intermediate transfer belt 50. The image is secondarily transferred onto the recording medium P, is fixed on the recording medium P by passing through the fixing roller pair 61 which is a fixing portion, and is discharged onto the paper discharge tray 68 formed on the upper part of the apparatus by the paper discharge roller pair 62.

In FIG. 8, 63 is a large number of recording media P.
Are stacked and held, 64 is a pickup roller for feeding the recording media P one by one from the paper feed cassette 63, and 65 is a timing of supplying the recording media P to the secondary transfer portion of the secondary transfer roller 66. Gate roller pair that defines
Reference numeral 66 denotes a secondary transfer roller as a secondary transfer unit that forms a secondary transfer portion with the intermediate transfer belt 50, and 67 denotes cleaning for removing toner remaining on the surface of the intermediate transfer belt 50 after the secondary transfer. It is a cleaning blade as a means.

When the organic EL array exposure head 1 of the present invention is used as the exposure head of such an electrophotographic image forming apparatus, the toner of the developer is microlenses 13.
It adheres to the lens surface of and becomes dirty, which causes image deterioration such as uneven exposure. Therefore, the work function Φ of the material used for the microlens 13 of the organic EL array exposure head 1
It is desirable to select _L , the work function Φ _B of the material of the partition wall 12, and the work function Φ _T of the material of the toner so that they simultaneously satisfy the following relationships.

| Φ _T −Φ _L | ≦ 0.2 eV (1) | Φ _T −Φ _B | ≧ 0.5 eV (2) When a combination of materials that satisfies the above conditions is used Since the toner that stains the organic EL array exposure head 1 adheres exclusively to the partition walls 12 around the microlens 13 and does not adhere to the lens surface, it is possible to prevent the lens surface of the microlens 13 from being soiled with toner.

The organic EL array exposure head of the present invention and the image forming apparatus using the same have been described above based on the embodiments, but the present invention is not limited to these embodiments and various modifications can be made.

[0075]

As is apparent from the above description, according to the organic EL array exposure head of the present invention and the image forming apparatus using the same, the light emitting portion of each organic EL element is provided on the light emitting side of the array of organic EL elements. Since a partition provided with an optical hole for blocking the mixing of the light emitted from the light emitting portion of the organic EL element adjacent to the light collecting position of the light emitted from the It is possible to obtain a sufficient resolution and contrast.

[Brief description of drawings]

FIG. 1 is an organic EL array exposure head according to the present invention.
It is a schematic plan view of an example.

FIG. 2 is a cross-sectional view of one pixel of an example in which emitted light is emitted from the cathode side of an organic EL element.

FIG. 3 is a diagram showing a configuration example of a piezo jet type head in an inkjet type.

FIG. 4 is a diagram for explaining how to form a microlens in the hole of the partition wall by an inkjet method.

FIG. 5 is a diagram for explaining that a ball lens and a hemispherical lens are dropped into holes in a partition wall to form microlenses.

FIG. 6 is a cross-sectional view of one pixel of an example in which emitted light is emitted from the anode side of an organic EL element.

FIG. 7 is a side view showing how light is condensed by the organic EL array exposure head according to the present invention.

FIG. 8 is a front view showing the overall schematic configuration of an example of a tandem type color image forming apparatus in which the organic EL array exposure head of the present invention is arranged.

[Explanation of symbols]

1 ... Organic EL array exposure head 1 (K, C, M, Y) ... Organic EL array exposure head 2, 2 '... array 3 ... Emitting pixel 4 ... Organic EL element 5 ... TFT 6 ... Glass substrate 7 ... Anode 8 ... Hole injection layer 9 ... Light emitting layer 10 ... Cathode 11 ... Adhesive layer 12 ... Partition 13 ... Micro lens 13 '... ball lens 13 "... hemispherical lens 14 ... hole 15 ... Backing member 16 ... Adhesive 17 ... Adhesive layer 18 ... Sealing member 20 ... Inkjet printing device 21 ... Head 22 ... Nozzle plate 23 ... diaphragm 24 ... Partition member (reservoir plate) 25 ... Ink chamber 26 ... Nozzle hole 28 ... Piezoelectric element 29 ... Electrode 41 (K, C, M, Y) ... Photosensitive drum 42 (K, C, M, Y) ... Charging means (corona charger) 44 (K, C, M, Y) ... Developing device 45 (K, C, M, Y) ... Primary transfer roller 46 (K, C, M, Y) ... Cleaning device 50 ... Intermediate transfer belt 51 ... Drive roller 52 ... Driven roller 53 ... Tension roller 61 ... Fixing roller pair 62 ... Paper ejection roller pair 63 ... Paper feed cassette 64 ... Pickup roller 65 ... Gate roller pair 66 ... Secondary transfer roller 67 ... Cleaning blade 68 ... Paper ejection tray S ... side P ... recording medium

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05B 33/14 F term (reference) 2C162 AE28 AE47 FA04 FA16 FA50 FA70 2H076 AB47 AB51 AB53 EA01 3K007 BB06 DB03 FA00

Claims (23)

[Claims] 1. An array of organic EL elements arranged in a pixel form in at least one column is provided on a long substrate, and a light emitting portion of each organic EL element is provided on a light emitting side of the array of the organic EL elements. An organic EL array exposure head, characterized in that a partition wall provided with an optical hole for blocking mixing of light emitted from a light emitting portion of an organic EL element adjacent to a condensing position of the emitted light is arranged. . 2. The organic EL array exposure head according to claim 1, wherein a positive lens is arranged at each hole position of the partition wall. 3. The organic EL array exposure head according to claim 1, wherein the substrate and the partition wall have substantially the same linear expansion coefficient. 4. The organic EL array exposure head according to claim 1, wherein the partition wall is formed by forming a hole in a metal plate. 5. The organic EL array exposure head according to claim 1, wherein the partition wall is formed by forming a hole by resin molding. 6. The organic EL array exposure head according to claim 1, wherein the partition wall and the substrate are integrally formed. 7. The organic EL device according to claim 2, wherein the height of the exit side surface of the partition wall is higher than that of the positive lens.
Array exposure head. 8. The organic EL device according to claim 2, wherein the height of the exit side surface of the partition wall is lower than that of the positive lens.
Array exposure head. 9. The organic EL array exposure head according to claim 1, wherein a wall surface of the hole of the partition wall is light reflective. 10. The organic EL array exposure head according to claim 1, wherein a wall surface of the hole of the partition wall is light absorbing. 11. The organic EL array exposure head according to claim 2, wherein the positive lens is made of resin. 12. The organic EL array exposure head according to claim 11, wherein the positive lens is formed in the hole of the partition wall by an inkjet method. 13. The organic EL array exposure head according to claim 11, wherein the positive lens is formed in the hole of the partition wall by a molding method. 14. The organic EL array exposure head according to claim 2, wherein the positive lens is made of glass. 15. The organic EL array exposure head according to claim 2, wherein the positive lens is a ball lens. 16. The organic EL device according to claim 1, wherein the organic EL device emits emitted light to the anode side.
The organic EL array exposure head according to any one of 1. 17. The organic EL device according to claim 1, wherein the organic EL device emits emitted light to the cathode side.
The organic EL array exposure head according to any one of 1. 18. The organic EL array exposure head according to claim 1, wherein the organic EL element is a polymer type. 19. The organic EL array exposure head according to claim 1, wherein the organic EL element is of a low molecular type. 20. The organic EL array exposure head according to claim 1, wherein the organic EL element is controlled in light emission by a TFT provided on the substrate. 21. An image forming apparatus comprising the organic EL array exposure head according to claim 1 as an exposure head for writing an image on an image carrier. 22. The image forming apparatus is provided with at least two image forming stations around which an image carrier is provided with a charging unit, an exposure head, a toner developing unit, and a transfer unit, and a transfer medium passes through each station. By
22. The image forming apparatus according to claim 21, wherein the image forming apparatus is a tandem type color image forming apparatus that forms a color image. 23. When the work function of the material of the positive lens is Φ _L , the work function of the material of the partition wall is Φ _B , and the work function of the material of the toner is Φ _T , | Φ _T −Φ _L | ≦ 0 23. The image forming apparatus according to claim 22, wherein the relationship of .2 eV (1) | Φ _T -Φ _B | ≧ 0.5 eV (2) is satisfied at the same time.