JP2003260811A - Optical print head, method of making the same, and image forming apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small optical print head having a long operational distance and low crosstalk, a method of making the same, and an image forming apparatus using the optical print head. <P>SOLUTION: There is disclosed the optical print head whereby a predetermined pattern is formed on an image carrier body 11 by projecting a modulated light beam from a light emitting section 2 of a light emitting element array or a modulated light beam passing through a shutter section 2 of a light shutter element array to the image carrier body 11. Ball lenses 10 are arranged on arrangement positions respectively corresponding to the light emitting sections 2 of the light emitting element array or the shutter sections 2 of the light shutter element array. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical printing head, a method of manufacturing the same, and an image forming apparatus using the same, and more particularly to individual elements of a light emitting element array such as an organic EL array or an optical shutter element array. The present invention relates to an optical printing head for arranging a ball lens and condensing a light flux from each element on a photoconductor, a method for manufacturing the same, 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.

In addition to the organic EL array, various proposals have been made to use an LED array or a liquid crystal shutter array as an exposure head for an image forming apparatus. In these cases, the light emitting portion of the LED array or the liquid crystal shutter array is also used. Many proposals use a condensing rod lens array to condense the light flux from the shutter section onto the photosensitive drum.

[0010]

In the above prior art, when an organic EL array or the like is used for an exposure head of a printer such as an electrophotographic system, the light emitting portion of the organic EL array or LED array or the shutter portion of the liquid crystal shutter array is used. When a condensing rod lens array is used to condense the luminous flux of the above on the photosensitive drum, the optical path length becomes long and the size becomes large.
Since the shutter portions are not arranged one-to-one with respect to each shutter portion, periodic light amount unevenness occurs, and further, since the condensing rod lens is sophisticated in terms of manufacturing method, an increase in cost cannot be avoided. Further, when the microlenses are integrated, there is a problem that the material of the microlenses is restricted.

The present invention has been made in view of such problems of the prior art, and an object thereof is to provide a light emitting element array such as an organic EL array, an LED array or an optical shutter element array such as a liquid crystal shutter array. The optical printing head, which is compact and has a long working distance and a small crosstalk, is provided by arranging a ball lens corresponding to each element and condensing the light flux from each element on the image carrier such as a photoconductor. A method and an image forming apparatus using the method.

[0012]

The optical printing head of the present invention that achieves the above-mentioned object is an image carrier for a modulated light beam from a light emitting section of a light emitting element array or a modulated light beam transmitted through a shutter section of an optical shutter element array. In an optical printing head which is projected onto the image carrier to form a predetermined pattern, a ball lens is arranged at an alignment position corresponding to each light emitting portion of the light emitting element array or each shutter portion of the optical shutter element array. It is characterized by

In this case, the ball lens is preferably fixed to the transparent member on the surface of the light emitting element array or the optical shutter element array by a transparent adhesive.

The diameter of the ball lens is preferably equal to or smaller than the arrangement pitch of the light emitting portions of the light emitting element array or the arrangement pitch of the shutter portions of the optical shutter element array.

Further, the refractive index of the ball lens is preferably equal to or higher than the refractive index of the transparent adhesive.

The thickness of the transparent member is preferably less than or equal to the diameter of the ball lens.

Further, it is desirable that a light shielding mask is arranged between the ball lenses.

In this case, the light-shielding mask comprises a light-shielding mask plate provided with holes corresponding to the arrangement of the ball lenses, the light-shielding mask plate is arranged on the exit side of the ball lens, and the ball lens is positioned by the light-shielding mask plate. At least one of the fixing can be performed.

As the light emitting element array, for example, an organic EL array can be used.

In the method of manufacturing the optical printing head of the present invention, the modulated light flux from the light emitting portion of the light emitting element array or the modulated light flux transmitted through the shutter portion of the optical shutter element array is projected on the image bearing member. An optical printing head for forming a predetermined pattern on the optical printing head, wherein ball lenses are arranged at aligned positions corresponding to the light emitting portions of the light emitting element array or the shutter portions of the optical shutter element array. In the method of manufacturing, the ball lens position is arranged on the transparent member on the surface of the light emitting element array or the optical shutter element array at an alignment position corresponding to each light emitting portion of the light emitting element array or each shutter portion of the optical shutter element array. Forming a hole pattern for determining the hole pattern, and dropping a ball lens into the hole pattern A method characterized by aligning the ball lens against the shutter portion each optical unit each or said optical shutter array.

In this case, the hole pattern may also be used as a light shielding means.

The present invention includes an image forming apparatus equipped with the above-described optical printing head as an exposure head for writing an image on an image carrier, one of which is, for example, an image carrier. At least two image forming stations each having a charging unit, an exposure head, a developing unit, and a transfer unit are provided around the image forming apparatus, and the transfer medium passes through each station to form a color image by a tandem system. There is.

In the present invention, since the ball lenses are arranged at the aligned positions corresponding to the light emitting portions of the light emitting element array or the shutter portions of the optical shutter element array, when the conventional condensing rod lens is used. The periodic unevenness in the amount of light does not occur. Further, the optical printing head can be downsized and a sufficient working distance can be secured.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an optical printing head of the present invention, a method of manufacturing the same, and an image forming apparatus using the same will be described based on Examples.

FIG. 1 is a schematic cross-sectional view showing the basic structure of an optical printing head according to the present invention. The surface of the transparent layer 3 or a light emitting portion 2 such as an organic EL or LED on the transparent layer 3 or at regular intervals is used. A shutter unit 2 such as a liquid crystal shutter is arranged to configure the light emitting element array 1 or the optical shutter element array 1. In the case of the optical shutter element array 1,
Although the shutter section 2 itself does not emit light, by disposing an illumination light source (backlight) behind it, the shutter section 2 becomes a secondary light source. Therefore, in the following description, the optical shutter section 2 also emits light unless otherwise specified. The light emitting element array 1 and the optical shutter element array 1 will be collectively referred to as a light modulating element array 1.

According to the present invention, the ball lenses 10 having the same shape and characteristics are arranged in one-to-one correspondence with the light emitting portions 2 of the light modulation element array 1 in the same positional relationship. In the case of FIG. 1, the light emitting portion 2 of the transparent layer 3 that constitutes the light modulation element array 1
The ball lenses 10 are arranged so as to be in contact with the surface on the opposite side to the position of 1 so that the centers of the ball lenses 10 are aligned with the centers of the light emitting portions 2. Then, the light flux from each light emitting unit 2 passes through the transparent layer 3 and is focused by the ball lens 10 on the image carrier 11 such as a photoconductor (in the case of electrophotography) that constitutes the projection target at a predetermined magnification. The ball lens 10
Are arranged.

Here, the ball lens 10 is a single positive lens made of a transparent sphere and has a focal length determined by the refractive index of the transparent body, the refractive index of the surroundings, and the radius.

With such a structure, the diameter of the ball lens 10, the distance from the light emitting portion 2 to the ball lens 10 (the thickness of the transparent layer 3 in the case of FIG. 1), the transparent layer 3 and the ball lens 10 By selecting the refractive index and the like between the light emitting portions 2 of the light modulation element array 1 so as to be projected onto the image carrier 11 while ensuring a one-to-one resolution, from the surface on the exit side of the ball lens 10. The distance (working distance) WD to the image carrier 11 can be secured.

FIG. 2 is a cross-sectional view in the case where a transparent adhesive is used to fix the ball lens 10 on the surface of the transparent layer 3 opposite to the light emitting portion 2, and each light emission of the light modulation element array 1 is shown. The ball lens 10 is fixed by the transparent adhesive layer 4 on the surface of the transparent layer 3 at the aligned position corresponding to the portion 2 one to one. In the case of FIG. 2, the diameter of each ball lens 10 and the light emitting portion 2
Since the arrangement pitch p is selected to be the same, the relative positioning of each light emitting portion 2 and each ball lens 10 is performed by the outer shape of the ball lens 10 by the contact between the ball lenses 10. As a matter of course, the diameter of the ball lens 10 must be equal to or smaller than the arrangement pitch p of the light emitting portions 2.

The refractive index of the transparent adhesive layer 4 supporting the ball lens 10 on the light emitting portion 2 side with respect to the light modulation element array 1 is not particularly limited, but may be equal to or lower than the refractive index of the ball lens 10. desirable. When such a refractive index relationship is selected, the spherical surface on the incident side of the ball lens 10 also acts as a refracting surface having a positive refractive power, so that the ball lens 10 can be brought closer to the light emitting section 2 (when the focal length becomes shorter, The object distance becomes shorter to obtain the same working distance WD.). Then, the NA (numerical aperture) of the light beam incident on the ball lens 10 becomes large, and the light beam emitted from the specific light emitting portion 2 enters not the corresponding ball lens 10 but the adjacent ball lens 10 to an uncorresponding pixel position. The resulting crosstalk is less, and an optical printing head with high resolution can be obtained.

The thickness of the transparent layer 3 which defines the distance between the light emitting portion 2 and the ball lens 10 is not particularly limited, but is preferably equal to or smaller than the diameter of the ball lens 10. That is, the NA of the light beam incident on the ball lens 10
The larger is, the less crosstalk the light flux emitted from the specific light emitting section 2 enters into the pixel position not corresponding through the ball lens 10 adjacent to the light beam corresponding to the light beam. Therefore, the thickness of the transparent layer 3 is reduced. The thinner the better, the smaller the diameter of the ball lens 10 is.

By the way, the ball lenses 10 are aligned in a one-to-one correspondence with the light emitting portions 2 of the light modulation element array 1.
For positioning, the diameter of each ball lens 10 and the arrangement pitch p of the light emitting portions 2 may be selected to be the same as in the case of FIG. 2, and the outer shape of the ball lens 10 may be used as a positioning reference. As shown in the cross-sectional view in FIG. 3A and the plan view seen from the bottom in FIG. 3A in FIG. 3B, between the transparent lens 3 for fixing the ball lens 10 and the ball lens 10,
It is also possible to drop the ball lens 10 so that the holes 6 for aligning the light emitting portions 2 are provided with the spacers 5 provided at the same pitch as the arrangement pitch p of the light emitting portions 2. As such a hole 6, a circular hole 6 having a diameter determined by the diameter of the ball lens 10 and the thickness of the spacer 5 is used, but the shape of the hole 6 may be a square other than a circle, a regular hexagon, or the like. It is desirable that such spacers 5 be formed by a photolithography method using a photoresist or the like. The ball lens 10 dropped into the hole 6 of the spacer 5 may be fixed with a transparent adhesive as shown in FIG. 2, or may be mechanically fixed as described later. Good.

FIG. 4 shows another embodiment. 4A is a cross-sectional view, and FIG. 3B is a plan view seen from the bottom of FIG. 3A. This embodiment is an embodiment in which a light shielding mask plate for shielding crosstalk light is provided between the ball lenses 10 and arranged in a one-to-one correspondence with each light emitting section 2 of the light modulation element array 1. Further, a light-shielding mask plate in which holes 8 through which a part of the ball lens 10 (a part of the spherical surface on the exit side in the case) enters and are exposed between the ball lenses 10 are provided at the same pitch as the arrangement pitch p of the light emitting units 2 7 is mounted on the ball lenses 10 arranged in an array, and a crosstalk in which a light beam emitted from a specific light emitting unit 2 is incident on an uncorresponding pixel position not through the corresponding ball lens 10 but through the adjacent ball lens 10. The light shielding mask plate 7 shields and absorbs light. Therefore, crosstalk is reduced, and an optical printing head with high resolution can be obtained. It is desirable that the holes 8 of the light shielding mask plate 7 are circular.

In this embodiment, the light shielding mask plate 7 is
Although it may be arranged between the incident side spherical surface of the ball lens 10 and the transparent layer 3, as shown in FIG. 4, in the case where the light shielding mask plate 7 is arranged on the emergent side spherical surface of the ball lens 10. As the light shielding mask plate 7, one having relatively high mechanical rigidity is used, and the light shielding mask plate 7 is used as the light modulation element array 1.
By applying a mechanical force that presses against, the light-shielding mask plate 7 can have both the positioning and fixing functions of the ball lens 10.

In the structure shown in FIG. 3, a spacer having a light blocking property may be used so that the spacer 5 also serves as a light blocking means.

Next, one embodiment of an optical printing head using the organic EL array according to the present invention will be described based on its manufacturing method.

As shown in the sectional view of FIG. 5 (a), an organic EL array in which organic EL light emitting portions 22 are formed at a constant pitch on a glass substrate 21 on which TFTs are formed by a method using an inkjet method described later. Twenty created. In addition,
In FIG. 5, reference numeral 29 is a partition wall (bank) around the organic EL light emitting unit 22.

Then, on the organic EL array 20,
It was covered with a transparent member 23 having a function of protecting the organic EL light emitting section 22.

After that, a black resist made of a photosensitive resin having a light-shielding property is applied to the transparent member 23, and a hole is formed at a position corresponding to the organic EL light emitting portion 22 to form a light-shielding pattern layer 25.
Was formed.

Next, as shown in FIG. 5B, the ultraviolet curing or thermosetting transparent adhesive 24 is discharged from the head 71 of the ink jet type printing apparatus 70,
It was dropped into the holes of the light shielding pattern layer 25.

Then, as shown in FIG. 6, the glass ball lenses 10 were laid out and aligned so as to enter the holes of the light shielding pattern layer 25. In this state, the transparent adhesive 24 between the transparent member 23 and the ball lens 10 was cured by UV irradiation or heat treatment from the entire surface.

In this way, the optical printing head using the organic EL array as shown in FIG. 6 was completed.

The dimensions, refractive index, etc. of each member in this example are as follows.

Dimension of organic EL light-emitting portion 22: pitch of 20 μm square organic EL light-emitting portion 22, arrangement: staggered arrangement of two lines with a pitch of 80 μm, pixel pitch on photoconductor is 40 μm, transparent member 23 thickness: 20 μm, transparent member Refractive index of 23: 1.52 Thickness of light shielding pattern layer 25: 2.5 μm Hole diameter of light shielding pattern layer 25: 40 μm Transparent adhesive 24: UV curable resin, refractive index 1.52 Diameter of ball lens 10: slightly less than 80 μm Refractive index of ball lens 10: 1.69 (glass: SF
8) W from the ball lens 10 to the image carrier (photoconductor) 11
D: 300 μm Imaging magnification: Approximately 4 times FIG. 7 shows an optical path tracing diagram of this embodiment, and FIG. 8 shows a light amount distribution diagram.

Next, a method for manufacturing the organic EL array 20 used in the above embodiment will be briefly described.

As shown in the plan view of FIG. 9, the organic EL array 20 comprises two arrays 31 and 31 ′ arranged in parallel so that the pixels are arranged in a staggered pattern. , 31 ′ are composed of a large number of pixels 32 arranged in a straight line, and the configuration of each pixel 32 is the same.
2 and the TFT 3 for controlling light emission of the organic EL light emitting section 22
3 and 3.

In FIG. 10, the organic EL light emitting portion 22 of one pixel 32 is shown.
A cross-sectional view including the TFT 33 and the TFT 33 is shown, which will be described in the order of manufacturing. First, the TFT 33 is formed on the glass substrate 21. Although various methods for manufacturing the TFT 33 are known. For example, a silicon oxide film is first deposited on the glass substrate 21, and then an amorphous silicon film is deposited. next,
This 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. Subsequently, 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, the first interlayer insulating film is deposited, the first contact hole is opened, the source line is formed, the second interlayer insulating film is deposited, the second contact hole is opened, and the metal pixel electrode is formed. Do it sequentially,
An array of TFTs 33 is completed (see, for example, "Polymer type organic EL display" in 8th Electronic Display Forum (2001.4.18)). Here, this metal pixel electrode serves as the cathode 34 of the organic EL light emitting portion 22 and also serves as the reflective layer of the organic EL light emitting portion 22, and is a metal thin film electrode of Mg, Ag, Al, Li or the like. It is formed.

Next, a partition wall (bank) 29 having a hole 35 corresponding to the organic EL light emitting portion 22 and having a predetermined height is formed. The partition 29 can be formed by an arbitrary method such as a photolithography method or a printing method, as disclosed in JP-A-2000-353594. For example, when the lithography method is used, an organic material is applied according to the height of the bank by a predetermined method such as spin coating, spray coating, roll coating, die coating, or dip coating, and a resist layer is applied thereon. And the partition wall 29
A mask is applied according to the shape, and the resist is exposed and developed to leave the resist adapted to the shape of the partition 29.
Finally, the partition wall material is etched to remove the partition wall material other than the mask. Further, the bank (convex portion) may be formed by two or more layers in which the lower layer is an inorganic material and the upper layer is an organic material. Further, as disclosed in Japanese Patent Laid-Open No. 2000-323276, the material forming the partition wall 29 is not particularly limited as long as it has durability against the solvent of the EL material, but it is treated with fluorocarbon gas plasma treatment to obtain Teflon ( Organic materials such as acrylic resins, epoxy resins, and photosensitive polyimides are preferable because they can be registered trademarks). It may be a laminated partition wall having an inorganic material such as liquid glass as a lower layer. Further, the partition wall 29 is preferably made black or opaque by mixing carbon black or the like into the above material.

Then, immediately before applying the ink composition for the light emitting layer of the organic EL, the substrate provided with the partition walls 29 is subjected to continuous plasma treatment of oxygen gas and fluorocarbon gas plasma. As a result, for example, the surface of the polyimide forming the partition walls 29 is made water-repellent and the surface of the cathode 34 is made hydrophilic, so that the wettability on the substrate side for finely patterning the inkjet droplets can be controlled. As an apparatus for generating plasma, an apparatus for generating plasma in vacuum or an apparatus for generating plasma in the atmosphere can be used as well.

Next, the ink composition for the light emitting layer is discharged from the head 71 of the ink jet type printing apparatus 70 into the hole 35 of the partition wall 29, and pattern coating is performed on the cathode 34 of each pixel. After coating, the solvent is removed and heat treatment is performed to form the light emitting layer 36.

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 expel an ink composition, and the thermal energy of a heater is used to generate air bubbles. Any of the thermal methods of ejecting the ink composition based on the generation may be used ("Fine Imaging and Hard Copy", 1999.
Issued 1.7 (Corona Inc.) p. 43). In Figure 11,
A configuration example of a piezo jet type head is shown. The inkjet head 71 includes, for example, a stainless nozzle plate 72 and a vibrating plate 73, which are joined together via a partition member (reservoir plate) 74. A partition member 74 is provided between the nozzle plate 72 and the vibration plate 73.
This forms a plurality of ink chambers 75 and a liquid pool (not shown). The interiors of the ink chamber 75 and the liquid pool are filled with the ink composition, and the ink chamber 75 and the liquid pool communicate with each other through the supply port. Furthermore, the nozzle plate 7
No. 2 is provided with a nozzle hole 76 for ejecting the ink composition from the ink chamber 75 in a jet shape. On the other hand, the ink jet head 71 is provided with an ink introduction hole for supplying the ink composition to the liquid pool. Further, on the surface of the vibrating plate 73 opposite to the surface facing the ink chamber 75, the piezoelectric element 7 is made to correspond to the position of the ink chamber 75.
8 are joined. This piezoelectric element 78 has a pair of electrodes 7.
The piezoelectric element 78 is located between 9 and bends so that the piezoelectric element 78 projects outward when energized. This increases the volume of the ink chamber 75. Therefore, the ink composition corresponding to the increased volume flows into the ink chamber 75 from the liquid reservoir through the supply port. Next, when the energization of the piezoelectric element 78 is released, both the piezoelectric element 78 and the diaphragm 73 return to their original shapes.
As a result, the space 75 also returns to its original volume, so the ink chamber 75
The pressure of the ink composition inside rises, and the ink composition is ejected from the nozzle holes 76 toward the substrate provided with the partition walls 29.

After the light emitting layer 36 is formed in the hole 35, the ink composition for the hole injection layer is discharged from the head 71 of the ink jet printing apparatus 70 onto the light emitting layer 36 in the hole 35, and then on the light emitting layer 36 of each pixel. Then, patterning is applied.
After coating, the solvent is removed and heat treatment is performed to form the hole injection layer 37.

The light emitting layer 36 and the hole injection layer 37 described above are used.
The order of may be reversed. It is desirable to dispose a layer more resistant to moisture on the surface side (the side farther from the substrate 21).

Further, the light emitting layer 36 and the hole injection layer 37 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

Regarding the material used for the light emitting layer 36 and the material used for the hole injection layer 37, see, for example, JP-A-10-.
Various publicly known ones such as No. 12377 and Japanese Patent Laid-Open No. 2000-323276 can be used, and the details are omitted.

After forming the light emitting layer 36 and the hole injection layer 37 in the hole 35 of the partition 29 in order, a transparent electrode 38 serving as an anode of the organic EL is deposited on the entire surface of the substrate by a vacuum deposition method to form the hole. The transparent electrode 38 is connected to the injection layer 37. Examples of the material of the transparent electrode 38 include a tin oxide film, an ITO film, a composite oxide film of indium oxide and zinc oxide, and a photolithography method, a sputtering method, a pyrosol method or the like can be adopted in addition to the vacuum deposition method. .

In this way, the organic EL array 20 used in the examples of FIGS. 5 to 8 is manufactured.

The partition wall 29 is made thicker and the hole 35 is made deeper to form the organic EL light emitting part 22 at the bottom of the hole 35, and a transparent material having a protective function is formed on the organic EL light emitting part 22. A transparent adhesive may be filled, and the ball lens 10 may be dropped into the upper portion of the hole 35 and aligned and fixed to the light emitting portion 22. In this case, the transparent member 23 can be omitted.

Now, the optical printing head 101 of one embodiment of the present invention as described above, as shown in the side view in FIG. 12, is on the surface S separated from the optical printing head 101 by the working distance WD, The luminous flux emitted from each organic EL light emitting section 22 is condensed in the same arrangement pattern as the pixel arrangement. Therefore, the surface S is relatively moved in the direction orthogonal to the longitudinal direction of the optical printing head 101, and each organic E of the optical printing head 101 is moved.
A predetermined pattern can be recorded on the surface S by controlling the light emission of the L light emitting unit 22 by the TFT 33.

Therefore, in the present invention, the optical printing head 10 using the organic EL array according to the present invention as described above.
1 is used for an exposure head of an electrophotographic color image forming apparatus, for example. FIG. 13 shows a similar 4 of the present invention.
Individual optical printing heads 101K, 101C, 101M, 10
4 similar photosensitive drums 41K, 41 corresponding to 1Y
FIG. 3 is a front view showing the overall schematic configuration of an example of a tandem type color image forming apparatus arranged at exposure positions C, 41M, and 41Y, respectively. As shown in FIG. 13, this image forming apparatus is tensioned by a driving roller 51, a driven roller 52, and a tension roller 53 to be stretched, and is circulatively driven in an arrow direction (counterclockwise direction) in the drawing. Photoconductors 41K, 41C, 41M, and 41Y each having a belt 50 and having photosensitive layers on the outer peripheral surface as four image carriers disposed at predetermined intervals with respect to the intermediate transfer belt 50 are disposed. 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. Photoconductor 41
K, 41C, 41M, and 41Y are rotationally driven in the direction of the arrow (clockwise direction) shown in synchronism with the driving of the intermediate transfer belt 50, but around each photoconductor 41 (K, C, M, Y), Charging means (corona charger) 42 (K, C,) for uniformly charging the outer peripheral surface of the photoconductor 41 (K, C, M, Y), respectively.
M, Y) and the outer peripheral surface uniformly charged by the charging means 42 (K, C, M, Y), the photoconductor 41 (K, C,
Optical printing head 10 using the above-described organic EL array of the present invention which sequentially performs line scanning in synchronization with the rotation of M, Y).
1 (K, C, M, Y) and this optical printing head 101
A developing device 44 (K, C, M, Y) that applies toner as a developer to the electrostatic latent image formed by (K, C, M, Y) to form a visible image (toner image); This developing device 44 (K,
C, M, Y) primary transfer roller 45 (K, C, M, Y) as a transfer unit that sequentially transfers the toner image developed by C, M, Y) to the intermediate transfer belt 50 that is a primary transfer target, and a photosensitive member after the transfer. It has a cleaning device 46 (K, C, M, Y) as a cleaning means for removing the toner remaining on the surface of the body 41 (K, C, M, Y).

Here, each optical printing head 101 (K, C,
M, Y) are, as shown in FIG.
The ball lenses 10 are arranged in a one-to-one correspondence and fixed, and the corresponding photoconductors 41 (K, C, M,
Y) apart from the surface by the working distance WD so that the array direction of each optical printing head 101 (K, C, M, Y) is along the generatrix of the photoconductor drum 41 (K, C, M, Y). Is installed. Then, each optical printing head 101 (K, C, M, Y)
Emission peak wavelength and the photoconductor 41 (K, C,
The sensitivity peak wavelengths of M, Y) are set to substantially match.

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. 13, reference numeral 63 is a paper feed cassette in which 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 secondary roller. A pair of gate rollers that define the timing of supplying the recording medium P to the secondary transfer portion of the next transfer roller 66, and 66 is a secondary transfer unit that forms a secondary transfer portion with the intermediate transfer belt 50. The rollers 67 are cleaning blades as a cleaning unit that removes the toner remaining on the surface of the intermediate transfer belt 50 after the secondary transfer.

The optical printing head of the present invention, the method of manufacturing the same, 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 are possible. is there. For example, at the time of fabrication, the ball lenses are fixed in a two-dimensional array on a sheet substrate of an organic EL array having a large rectangular two-dimensional array, and then cut into a line for mass production. At this time, by forming the hole pattern (FIG. 3) two-dimensionally, the ball lens can be positioned and aligned at one time. Instead of using the hole pattern, it is also possible to apply an adhesive in a spot corresponding to the light emitting portion or the like by an ink jet method or the like and fix the ball lens with the adhesive.

[0066]

As is apparent from the above description, according to the optical printing head, the method of manufacturing the same, and the image forming apparatus using the same of the present invention, each of the light emitting portions of the light emitting element array or the shutter of the optical shutter element array is provided. Since the ball lenses are arranged at the alignment positions corresponding to the respective parts, the periodic unevenness in the amount of light that occurs when the conventional condensing rod lens is used does not occur. Further, the optical printing head can be downsized and a sufficient working distance can be secured.

As described above, the optical printing head of the present invention has little unevenness in exposure as an exposure head for an electrophotographic printer, has a simple structure, does not require a separate optical system, and is inexpensive. Can be provided to.

The ball lens can be fixed by the transparent adhesive, and the incident surface of the ball lens can also function as a convex lens by selecting the relationship of the refractive index. Further, by using the hole pattern for the positioning, the positioning can be accurately and easily performed.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a basic configuration of an optical printing head according to the present invention.

FIG. 2 is a cross-sectional view when a transparent adhesive is used to fix the ball lens.

3A and 3B are a sectional view and a plan view in the case of interposing a spacer having a hole pattern for positioning the ball lens.

4A and 4B are a cross-sectional view and a plan view of an embodiment in which a light-shielding mask plate that shields crosstalk light is provided.

FIG. 5 is a diagram for explaining a manufacturing method of an example of the optical printing head using the organic EL array according to the present invention.

6 is a sectional view of an optical printing head using the organic EL array obtained by the manufacturing method of FIG.

FIG. 7 is an optical path tracing diagram of the optical printing head of the embodiment of FIGS.

8 is a light quantity distribution diagram of the optical printing head of the embodiment of FIGS.

FIG. 9 is a plan view of an organic EL array used in the examples of FIGS.

10 is a cross-sectional view of one pixel of the array of FIG.

FIG. 11 is a diagram showing a configuration example of a piezo jet type head in an inkjet type.

FIG. 12 is a side view showing how light is condensed by the optical printing head of the embodiment shown in FIGS.

FIG. 13 is a front view showing the overall schematic configuration of an example of a tandem type color image forming apparatus in which the optical printing head of the present invention is arranged.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Light modulation element array (light emitting element array, optical shutter element array) 2 ... Light emitting portion (shutter portion) 3 ... Transparent layer 10 ... Ball lens 11 ... Image carrier 4 ... Transparent adhesive layer 5 ... Spacer 6 ... Hole 7 ... Light-shielding mask plate 8 ... Hole 20 ... Organic EL array 21 ... Glass substrate 22 ... Organic EL light-emitting part 23 ... Transparent member 24 ... Transparent adhesive (UV curing type, thermosetting type) 25 ... Shading pattern layer 29 ... Partition (bank) ) 31, 31 '... Array 32 ... Pixel 33 ... TFT 34 ... Cathode 35 ... Hole 36 ... Light emitting layer 37 ... Hole injection layer 38 ... Transparent 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 ... Followed 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 70 Inkjet printing device 71 ... Head 72 ... Nozzle plate 73 ... Vibration plate 74 ... Partition member (reservoir plate) 75 ... Ink chamber 76 ... Nozzle hole 78 ... Piezoelectric element 79 ... Electrode 101 (K, C, M, Y) ... Optical printing head S ... Surface P ... recording medium using organic EL array

Claims (12)

[Claims] 1. An optical printing method for projecting a modulated light beam from a light emitting section of a light emitting element array or a modulated light beam transmitted through a shutter section of an optical shutter element array onto an image carrier to form a predetermined pattern on the image carrier. In the head, a ball lens is arranged at an alignment position corresponding to each light emitting portion of the light emitting element array or each shutter portion of the optical shutter element array. 2. The optical printing head according to claim 1, wherein the ball lens is fixed to a transparent member on the surface of the light emitting element array or the optical shutter element array with a transparent adhesive. 3. The light according to claim 1, wherein a diameter of the ball lens is equal to or smaller than an arrangement pitch of light emitting portions of the light emitting element array or an arrangement pitch of shutter portions of the optical shutter element array. Printing head. 4. The optical printing head according to claim 2, wherein a refractive index of the ball lens is equal to or higher than a refractive index of the transparent adhesive. 5. The optical printing head according to claim 2, wherein the thickness of the transparent member is less than or equal to the diameter of the ball lens. 6. The optical printing head according to claim 1, further comprising a light shielding mask arranged between the ball lenses. 7. The light-shielding mask comprises a light-shielding mask plate provided with holes corresponding to the arrangement of the ball lenses, the light-shielding mask plate is disposed on an exit side of the ball lens, and the light-shielding mask plate allows the ball lenses to be arranged. 7. The optical printing head according to claim 6, wherein at least one of positioning and fixing is performed. 8. The optical printing head according to claim 1, wherein the light emitting element array is an organic EL array. 9. An optical printing method for projecting a modulated light beam from a light emitting portion of a light emitting element array or a modulated light beam transmitted through a shutter portion of an optical shutter element array onto an image carrier to form a predetermined pattern on the image carrier. A method for producing an optical printing head, comprising a head and a ball lens arranged at an alignment position corresponding to each light emitting portion of the light emitting element array or each shutter portion of the optical shutter element array, wherein the light emitting element array or On the transparent member on the surface of the optical shutter element array, a hole pattern for determining the position of the ball lens is formed at an alignment position corresponding to each light emitting portion of the light emitting element array or each shutter portion of the optical shutter element array, A ball lens is dropped into the hole pattern so that each light emitting portion of the light emitting element array or the optical shutter. A method of manufacturing an optical printing head, characterized in that a ball lens is aligned with each shutter portion of the element array. 10. The method of manufacturing an optical printing head according to claim 9, wherein the hole pattern also serves as a light shielding means. 11. An image forming apparatus comprising the optical printing head according to claim 1 as an exposure head for writing an image on an image carrier. 12. The image forming apparatus is provided with at least two image forming stations having a charging unit, an exposure head, a developing unit, and a transfer unit around the image carrier, and a transfer medium passes through each station. 12. The image forming apparatus according to claim 11, wherein the image forming apparatus is a tandem type color image forming apparatus that forms a color image.