JP2009051200A - Method for manufacturing organic electroluminescence exposure head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small size optical print head focusing the luminous fluxes from the respective elements onto a photosensitive body in sufficient resolution and contrast by reducing crosstalk and the image forming device using the same. <P>SOLUTION: The optical print head forms a predetermined pattern on an image carrier 5 by projecting the modulated luminous fluxes from the light emitting sections 2 of the light emitting element array 1 or the modulated luminous fluxes passing through the shutter sections 2 of the light shutter element array 1 onto the image carrier 5, the optical print head is constituted by arranging microlenses 4 in an aligning positions corresponding to the respective light emitting sections 2 of the light emitting element array 1 or the respective shutter sections 2 of the light shutter element array 1 via a transparent body 3 and a low refractive layer 6 with a lower refractive index than that of the transparent body 3 in turns. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical printing head and an image forming apparatus using the same, and in particular, a ball lens is arranged corresponding to each element of a light emitting element array such as an organic EL array or an optical shutter element array, and each element is arranged. The present invention relates to an optical printing head that collects the luminous flux on a photosensitive member and an image forming apparatus using the same.

  Conventionally, various types using an organic EL array as an exposure head for an image forming apparatus have been proposed. The related items are as follows.

  In Patent Document 1, a condensing rod is used to collectively produce an organic EL array on an insulating substrate such as glass, combine a separate driver IC, and form an image of the light emitting portion of the organic EL array on a photosensitive drum. A lens array is used.

  In Patent Document 2, a one-chip organic EL array having a plurality of rows is used, and an optical system that forms an image of the light emitting portion on a photosensitive drum is unknown. Note that the EL layer of the organic EL array is deposited by vapor deposition.

  In Patent Document 3, a microlens is formed on the upper surface of the substrate by the in-o exchange method, or a microlens is formed by a method using a photoresist on the back surface of the substrate or a replica method, and a resonator structure is provided in alignment with the microlens. An organic EL array is deposited by vapor deposition.

  Patent Document 4 relates to a method for manufacturing an active matrix organic EL display, and forms an organic light emitting layer on a glass substrate having a thin film transistor by an ink jet method.

  In Patent Document 5, a hole injection layer and an organic light emitting layer of an organic EL element are formed by providing a partition wall and applying by an ink jet method.

  In Patent Document 6, a light emitting layer and a TFT layer for controlling the light emission are formed inside a photosensitive drum to constitute a printer.

In addition to organic EL arrays, various proposals have been made to use LED arrays or liquid crystal shutter arrays as exposure heads for image forming apparatuses. In these cases as well, from the light emitting section of the LED array or the shutter section of the liquid crystal shutter array. Many proposals have been made to use a condensing rod lens array or microlens array to collect the light beam on the photosensitive drum.
JP-A-10-55890 JP 11-198433 A JP 2000-77188 A Japanese Patent Laid-Open No. 10-12377 JP 2000-323276 A JP 2001-18441 A JP 2000-353594 A JP 2000-323276 A Japanese Patent Laid-Open No. 10-12377 JP 2000-323276 A

  In the above prior art, when an organic EL array or the like is used for an exposure head of an electrophotographic printer or the like, the light flux from the light emitting portion of the organic EL array, the LED array, or the shutter portion of the liquid crystal shutter array is condensed on the photosensitive drum. When a condensing rod lens array is used, the optical path length becomes long and the size increases, and the condensing rod lens is not arranged one-on-one with respect to each light emitting portion and each shutter portion, so that it is periodic. In addition, unevenness in the amount of light occurs, and 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 one-on-one with respect to each light emitting part and each shutter part. There is a tendency for crosstalk to be incident on pixel positions that do not correspond via the microlens, leading to a decrease in resolution and the like.

  The present invention has been made in view of such problems of the prior art, and the object thereof is to individual elements of a light emitting element array such as an organic EL array and an LED array, or an optical shutter element array such as a liquid crystal shutter array. A small-sized light that reduces the crosstalk of the optical printing head that arranges the microlens and correspondingly concentrates the light flux from each element on the image carrier such as a photoconductor with sufficient resolution and contrast. It is an object to provide a printing head and an image forming apparatus using the same.

  The first optical printing head of the present invention that achieves the above object projects a modulated light beam from a light emitting part of a light emitting element array or a modulated light beam transmitted through a shutter part of an optical shutter element array onto an image carrier. In an optical printing head for forming a predetermined pattern on a carrier, a hemispherical micro-transistor is arranged through a transparent body having a predetermined thickness at an alignment position corresponding to each light emitting section of the light emitting element array or each shutter section of the optical shutter element array. A lens is disposed, and light incident on the hemispherical microlens adjacent to the hemispherical microlens at the corresponding position from the light emitting unit or the shutter unit is totally reflected or refracted by the hemispherical refracting surface. However, the thickness of the transparent body is set so as not to face the image carrier.

The second optical printing head of the present invention projects a modulated light beam from the light emitting part of the light emitting element array or a modulated light beam transmitted through the shutter part of the optical shutter element array onto the image carrier to give a predetermined amount to the image carrier. In the optical printing head for forming a pattern, a hemispherical microlens is arranged through a transparent body having a predetermined thickness at an alignment position corresponding to each light emitting section of the light emitting element array or each shutter section of the optical shutter element array. And at least part of the light incident on the hemispherical microlens adjacent to the hemispherical microlens at the corresponding position from the light emitting unit or the shutter unit is totally reflected by the hemispherical refracting surface. The thickness is set.

  In the first and second optical printing heads, the thickness of the transparent body is set to 50% or less of the arrangement pitch of the light emitting parts of the light emitting element array or the arrangement pitch of the shutter parts of the optical shutter element array. desirable.

  The third optical printing head of the present invention projects a modulated light beam from the light emitting part of the light emitting element array or a modulated light beam transmitted through the shutter part of the optical shutter element array onto the image carrier to give a predetermined amount to the image carrier. In the optical printing head for forming the pattern, the transparent body and the refractive index lower than the refractive index of the transparent body are sequentially arranged at the alignment positions corresponding to the light emitting sections of the light emitting element array or the shutter sections of the optical shutter element array. The microlens is arranged through the low refractive index layer.

  In this case, it is desirable that the low refractive index layer is an air layer, or is made of any one of magnesium fluoride, silica airgel, and fluororesin.

  The above microlenses can be made of glass or plastic.

  Moreover, it is desirable that the above microlens is provided with an antireflection coating.

  In the third optical printing head, the microlens can be composed of a hemispherical lens or a ball lens.

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

  In the present invention, even if light incident on the hemispherical microlens adjacent to the hemispherical microlens at the corresponding position from the light emitting unit or the shutter unit is totally reflected or refracted by the hemispherical refracting surface, the image is held. The thickness of the transparent body is set so as not to face the body, or at least part of the light incident on the hemispherical microlens adjacent to the hemispherical microlens at the corresponding position from the light emitting part or the shutter part is the hemispherical The thickness of the transparent body is set so as to be totally reflected by the refracting surface of the transparent body, or the transparent body and the transparent body in order at the alignment position corresponding to each light emitting section of the light emitting element array or each shutter section of the optical shutter element array. Since the microlens is arranged through a low refractive index layer having a refractive index lower than that of the transparent body, the crosstalk light and stray light can be reduced. It can be. In addition, when a low refractive index layer is interposed, it is possible to increase the distance between the microlens and the light emitting unit or the shutter unit without causing crosstalk, thereby reducing the microlens magnification. Since the energy density on the image carrier is increased and the diameter of the focused spot can be reduced, sufficient resolution and contrast can be obtained.

  Hereinafter, an optical printing head of the present invention and an image forming apparatus using the same will be described based on embodiments.

FIG. 1 is a schematic cross-sectional view showing a configuration of an optical printing head according to a first embodiment of the present invention, and a light emitting portion 2 such as an organic EL or LED or a shutter portion such as a liquid crystal shutter on the surface at a constant period. 2 is arranged to form the light emitting element array 1 or the optical shutter element array 1. In the case of the optical shutter element array 1, the shutter unit 2 itself does not emit light, but the shutter unit 2 becomes a secondary light source by disposing an illumination light source (backlight) in the back. As long as there is no, the light shutter part 2 is also called the light emission part 2, and the light emitting element array 1 and the light shutter element array 1 are also called the light modulation element array 1 together.

  In the present embodiment, a microlens made of a hemispherical lens is arranged on the opposite surface of the transparent body 3 through the transparent body 3 having a protective function at an alignment position corresponding to each light emitting portion 2 of the light modulation element array 1 on a one-to-one basis. 4 is fixedly disposed by bonding. Then, the light flux from each light emitting unit 2 passes through the transparent body 3 and is condensed at a predetermined magnification on the image carrier 5 such as a photosensitive body (in the case of electrophotography) constituting the projection body by the microlens 4. Has been placed.

  Then, by appropriately selecting the thickness of the transparent body 3 as will be described later, the light ◯ 1 incident on the refractive surface (hemispherical surface) of the microlens 4 corresponding to the light emitting unit 2 is transmitted by the corresponding microlens 4. It is condensed on the image carrier 5. A predetermined line pattern emitted from the light modulation element array 1 can be written on the image carrier 5 by the condensed light flux.

  On the other hand, among the light emitted from the light emitting unit 2 and incident on the adjacent microlens 4, the light ○ 2 close to the microlens 4 corresponding to the light emitting unit 2 is incident on the refractive surface (hemispherical surface) of the adjacent microlens 4. It is incident at an incident angle greater than the critical angle and is totally reflected and does not reach the image carrier 5. Therefore, this light ○ 2 does not become crosstalk light.

  Of the light emitted from the light emitting unit 2 and incident on the adjacent microlens 4, the light ○ 3 incident on the side opposite to the microlens 4 corresponding to the light emitting unit 2 is the refractive surface of the adjacent microlens 4 ( Refracted by the hemispherical surface) and incident on the adjacent microlens 4, so that it does not reach the image carrier 5. Therefore, this light ○ 3 is not crosstalk light.

  By selecting the thickness of the transparent body 3 so as to satisfy such a condition, it is possible to print with less crosstalk between pixels.

  Hereinafter, specific numerical examples of this embodiment will be shown.

Refractive index of the transparent body 3: 1.73
Thickness of the transparent body 3: 20 μm
Microlens 4 shape: hemisphere, diameter 80 μm
Refractive index of the microlens 4: 1.95
Light emitting part 2 pitch: 80 μm
Size of light emitting unit 2: 10 μm square Distance between microlens 4 and image carrier 5: 300 μm
An optical path tracking diagram in such a specific example is shown in FIG. 2, and a light amount distribution diagram thereof is shown in FIG. It is clear from FIGS. 2 and 3 that there is almost no crosstalk in this specific numerical example.

  In this numerical example, if the thickness of the transparent body 3 is too large to be 40 μm or more, crosstalk occurs as shown in FIG. 4 and the resolution and contrast are lowered. Therefore, the thickness of the transparent body 3 is desirably 50% or less, more preferably 30% or less, of the arrangement pitch of the light emitting portions 2.

FIG. 5 is a schematic cross-sectional view showing the configuration of the optical printing head according to the second embodiment of the present invention. In this embodiment, the transparent body 3 provided on the surface of the light modulation element array 1, Light modulation element array 1
An air layer 6 is interposed between the microlenses 4 arranged in alignment with the light emitting units 2.

  With this configuration, the light ○ 1 that is about to enter the refracting surface (convex surface) of the microlens 4 corresponding to the light emitting unit 2 is transmitted through the air layer 6 and is formed on the image carrier 5 by the corresponding microlens 4. Focused. A predetermined line pattern emitted from the light modulation element array 1 can be written on the image carrier 5 by the condensed light flux.

  On the other hand, among the light emitted from the light emitting unit 2 and going to enter the adjacent microlens 4, the light ○ 2 close to the microlens 4 corresponding to the light emitting unit 2 is the refractive surface (convex surface) of the adjacent microlens 4. Is incident at an angle of incidence greater than the critical angle and is totally reflected and does not reach the image carrier 5. Therefore, this light ○ 2 does not become crosstalk light.

  Of the light emitted from the light emitting unit 2 and entering the adjacent microlens 4, the light ○ 3 incident on the side away from the microlens 4 corresponding to the light emitting unit 2 is incident on the air layer 6 at a critical angle. Since it is incident at the above incident angle, it is totally reflected at the boundary with the air layer 6, and therefore does not reach the image carrier 5. Therefore, this light ○ 3 is not crosstalk light.

  Thus, by interposing the air layer 6 having a refractive index lower than that of the transparent body 3 at an appropriate position between the light emitting unit 2 and the microlens 4, it is possible to perform printing with less crosstalk between pixels. In order to provide the air layer 6 between the transparent body 3 and the microlens 4, the outer frame may be fixed so as to provide a gap between the transparent body 3 and the microlens 4, or between the substrates of the liquid crystal cell. A bead or the like similar to a spacer for providing a gap may be interposed between the transparent body 3 and the substrate of the microlens 4.

  Hereinafter, specific numerical examples of this embodiment will be shown.

Refractive index of the transparent body 3: 1.73
Transparent body 3 thickness: 50 μm
Air layer 6 thickness: 5 μm
Microlens 4 shape: hemisphere, diameter 80 μm
Refractive index of the microlens 4: 1.52
Light emitting part 2 pitch: 80 μm
Size of light emitting unit 2: 10 μm square Distance between microlens 4 and image carrier 5: 300 μm
FIG. 6 shows an optical path tracking diagram in such a specific example, and FIG. 7 shows a light amount distribution diagram thereof. It is clear from FIGS. 6 and 7 that there is almost no crosstalk in this specific numerical example.

  As a comparative example, FIG. 8 shows an optical path tracking diagram in the case where an adhesive having a refractive index of 1.52 is used instead of an air layer of a low refractive index layer. In this case, crosstalk has occurred.

  In this embodiment, crosstalk does not occur even if the thickness of the transparent body 3 is made thicker than in the first embodiment. Therefore, the magnification of the image on the image carrier 5 of the light emitting unit 2 by the microlens 4 can be lowered, and the light collecting performance is improved. Further, the refractive index of the microlens 4 can be lowered, and a plastic lens can be used as the microlens 4.

  The same effect can be obtained by using a low refractive index layer such as silica airgel (refractive index: 1.03) instead of the air layer 6.

In addition, when a substance having a refractive index of around 1.3 such as magnesium fluoride (MgF _2, refractive index: 1.38) or fluororesin (refractive index: 1.34) is used instead of the air layer 6, it is low. Although the effect of total reflection of the crosstalk light by the refractive index layer is reduced, light having a large angle is totally reflected, so that there is an effect of reducing stray light.

  FIG. 9 is a schematic cross-sectional view showing the configuration of the optical printing head according to the third embodiment of the present invention. In this embodiment, a glass ball lens 7 is used for each light emission of the light modulation element array 1. The light beams from the light emitting section 2 are condensed on the image carrier 5 at a predetermined magnification by the ball lens 7 at the corresponding position. Then, a fluororesin coat layer 8 having a refractive index of 1.34 is provided on the surface of the transparent body 3 as a low refractive index layer having a function of totally reflecting the crosstalk light, and the ball lens 7 is formed on the transparent adhesive 9. Is fixed by bonding. The refractive index of the transparent body 3 is 1.52, and the refractive index of the glass of the ball lens 7 is 1.78. As shown in FIG. 9, the light incident on the ball lens 7 in front of the light emitting unit 2 is condensed on the image carrier 5, and the light emitted from the light emitting unit 2 at a large angle is at the interface of the fluororesin coating layer 8. It is totally reflected and does not enter the ball lens 7 and does not reach the image carrier 5. Therefore, stray light is reduced and printing quality is improved.

  Here, the ball lens 7 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 surrounding refractive index, and the radius.

  FIG. 10 shows a hemispherical microlens 4 on both surfaces of a transparent substrate 11 as a microlens 10 for condensing the light beam from the air layer 6 and the light emitting unit 2 on the image carrier 5 to totally reflect the crosstalk light. An example is shown in which an ink jet method or the like prepared by aligning the front and back sides is used. An air layer 6 is formed between the transparent body 3 and the transparent substrate 11 via a spacer 12. The crosstalk and stray light reducing effects are apparent from the above-described embodiments.

  In any of the above embodiments, the surface of the microlenses 4, 7, and 10 may be provided with an antireflection coating or an antistatic coating.

  Here, an example of an organic EL array that can be used as the light modulation element array 1 will be described.

  As shown in the plan view of FIG. 11, the organic EL array 20 in this example is an array in which two rows of arrays 31 and 31 ′ are arranged in parallel so that the pixels are staggered. Reference numeral 31 ′ includes a large number of pixels 32 arranged in a straight line. Each pixel 32 has the same configuration, and includes an organic EL light emitting unit 22 and a TFT 33 that controls light emission of the organic EL light emitting unit 22.

  FIG. 12 shows a cross-sectional view including the organic EL light emitting unit 22 of one pixel 32 and the TFT 33, which will be described in the order of production. First, the TFT 33 is formed on the glass substrate 21. Various methods for manufacturing the TFT 33 are known. For example, a silicon oxide film is first deposited on the glass substrate 21, and an amorphous silicon film is further deposited. Next, the amorphous silicon film is crystallized by irradiating it with an excimer laser beam to form a polysilicon film serving as a channel. After patterning the polysilicon film, a gate insulating film is deposited, and a gate electrode made of tantalum nitride is formed. Subsequently, the source / drain portions of the N-channel TFT are formed by phosphorus ion implantation, and the source / drain portions of the P-channel TFT are formed by boron ion implantation. 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. This is sequentially performed to complete the array of TFTs 33 (see, for example, “8th Electronic Display Forum (2001.18)“ polymer organic EL display ”). Here, the metal pixel electrode serves as the cathode 34 of the organic EL light emitting unit 22 and also serves as a reflective layer of the organic EL light emitting unit 22, and is a metal thin film electrode such as 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 unit 22 and having a predetermined height is formed. As disclosed in Patent Document 7, the partition walls 29 can be formed by an arbitrary method such as a photolithography method or a printing method. For example, when using the lithography method, an organic material is applied in accordance with the height of the bank by a predetermined method such as spin coating, spray coating, roll coating, die coating, dip coating, and a resist layer is applied thereon. Then, a mask is applied according to the shape of the partition wall 29, and the resist is exposed and developed to leave the resist according to the shape of the partition wall 29. Finally, the partition wall material is etched to remove the partition wall material other than the mask. Moreover, you may form a bank (convex part) by two or more layers by which the lower layer was comprised by the inorganic substance and the upper layer was comprised by the organic substance. Further, as disclosed in Patent Document 8, the material constituting the partition wall 29 is not particularly limited as long as it has durability against the solvent of the EL material, but it can be converted to Teflon by fluorocarbon gas plasma treatment. For example, an organic material such as an acrylic resin, an epoxy resin, or a photosensitive polyimide is preferable. The laminated partition which made inorganic materials, such as liquid glass, the lower layer may be sufficient. The partition wall 29 is preferably black or opaque by mixing carbon black or the like with the above material.

  Next, immediately before the organic EL light-emitting layer ink composition is applied, the substrate provided with the partition walls 29 is subjected to continuous plasma treatment with oxygen gas and fluorocarbon gas plasma. Thereby, for example, the polyimide surface constituting the partition wall 29 is water repellent and the cathode 34 surface is hydrophilic, and the wettability on the substrate side for finely patterning the ink jet droplets can be controlled. As an apparatus for generating plasma, an apparatus for generating plasma in a vacuum or an apparatus for generating plasma in the atmosphere can be used similarly.

  Next, the ink composition for the light emitting layer is discharged from the head 71 of the ink jet printing apparatus 70 into the hole 35 of the partition wall 29, and patterning is applied 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 system referred to in the present invention is based on a piezo jet system that ejects an ink composition using mechanical energy of a piezoelectric element or the like, and bubbles are generated using the thermal energy of a heater, and the generation of the bubbles Any of the thermal methods for discharging the ink composition may be used (“Fine Imaging and Hard Copy” 1999.1.7 (Corona Co., Ltd.), edited by the Japan Photography Society and the Imaging Society of Japan Joint Publishing Committee). 43). FIG. 13 shows a configuration example of a piezo jet head. The inkjet head 71 includes, for example, a stainless steel nozzle plate 72 and a vibration plate 73, and both are joined via a partition member (reservoir plate) 74. A plurality of ink chambers 75 and liquid reservoirs (not shown) are formed by the partition member 74 between the nozzle plate 72 and the vibration plate 73. The ink chamber 75 and the inside of the liquid reservoir are filled with the ink composition, and the ink chamber 75 and the liquid reservoir communicate with each other through the supply port. Further, the nozzle plate 72 is provided with a nozzle hole 76 for ejecting the ink composition from the ink chamber 75 into a jet. On the other hand, the ink jet head 71 is formed with an ink introduction hole for supplying an ink composition to the liquid reservoir. A piezoelectric element 78 is bonded to the surface of the vibration plate 73 opposite to the surface facing the ink chamber 75 in correspondence with the position of the ink chamber 75. The piezoelectric element 78 is located between the pair of electrodes 79 and bends so that the piezoelectric element 78 protrudes outward when energized. As a result, the volume of the ink chamber 75 increases. Therefore, the ink composition corresponding to the increased volume in the ink chamber 75 flows from the liquid reservoir through the supply port. Next, when energization to 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 that the pressure of the ink composition inside the ink chamber 75 rises, and the ink composition is ejected from the nozzle hole 76 toward the substrate on which the partition wall 29 is provided.

After forming the light emitting layer 36 in the hole 35, the hole injection layer ink composition is applied to the light emitting layer 3 in the hole 35.
6 is discharged from the head 71 of the ink jet printing apparatus 70, and patterning is applied on the light emitting layer 36 of each pixel. After coating, the solvent is removed and heat treatment is performed to form the hole injection layer 37.

  The order of the light emitting layer 36 and the hole injection layer 37 may be reversed. It is desirable to arrange a layer that is 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 can be formed by a known spin coating method, dip method or vapor deposition method instead of forming the ink composition by applying the ink composition by the ink jet method as described above. .

  As materials used for the light emitting layer 36 and materials used for the hole injection layer 37, various known materials can be used, for example, in Patent Document 9, Patent Document 10 and the like, and details thereof are omitted.

  A light emitting layer 36 and a hole injection layer 37 are formed in order in the holes 35 of the partition wall 29, and then a transparent electrode 38 serving as an anode of an organic EL is deposited on the entire surface of the substrate by a vacuum evaporation method. The transparent electrode 38 is connected to the top. As the material of the transparent electrode 38, there are a tin oxide film, an ITO film, a composite oxide film of indium oxide and zinc oxide, etc. In addition to the vacuum deposition method, a photolithography method, a sputtering method, a pyrosol method, etc. can be adopted. .

  In this way, the organic EL array 20 that can be used as the light modulation element array 1 is manufactured.

  Now, the optical printing head 101 with reduced crosstalk according to the present invention as described above (this embodiment uses the organic EL array 20 of FIGS. 11 and 12 as the light modulation element array 1 and has the configuration of FIG. As shown in the side view of FIG. 14, each organic EL light emitting unit 22 (with the same arrangement pattern as the pixel arrangement on the surface S separated from the optical printing head 101 by the working distance WD is shown. (Corresponding to the light emitting section 2 of the light modulation element array 1). Therefore, the surface S is relatively moved in the direction orthogonal to the longitudinal direction of the optical printing head 101, and the light emission of each organic EL light emitting unit 22 of the optical printing head 101 is controlled by the TFT 33. A predetermined pattern can be recorded on S.

Therefore, in the present invention, the optical printing head 101 using the organic EL array as described above is used, for example, as an exposure head of an electrophotographic color image forming apparatus. FIG. 15 shows a tandem system in which four similar optical printing heads 101K, 101C, 101M, and 101Y of the present invention are arranged at the exposure positions of corresponding four photosensitive drums 41K, 41C, 41M, and 41Y, respectively. 1 is a front view illustrating a schematic configuration of an example of the color image forming apparatus of FIG. As shown in FIG. 15, this image forming apparatus is tensioned by a driving roller 51, a driven roller 52, and a tension roller 53, and is intermediately transferred by being circulated in the direction indicated by the arrow (counterclockwise). Photosensitive members 41K, 41C, 41M, and 41Y each having a photosensitive layer are disposed on the outer peripheral surface as four image carriers that are provided with a belt 50 and are disposed at a predetermined interval with respect to the intermediate transfer belt 50. “K”, “C”, “M”, and “Y” added after the symbols mean black, cyan, magenta, and yellow, respectively, and indicate that the photoconductors are for black, cyan, magenta, and yellow, respectively. The same applies to other members. The photoconductors 41K, 41C, 41M, and 41Y are driven to rotate in the direction indicated by the arrow (clockwise) in synchronization with the driving of the intermediate transfer belt 50, but around each photoconductor 41 (K, C, M, Y). Are respectively charging means (corona charger) 42 (K, C, M, Y) for uniformly charging the outer peripheral surface of the photoconductor 41 (K, C, M, Y) and this charging means 42 (K, An organic EL array as described above according to the present invention that sequentially scans the outer peripheral surface uniformly charged by C, M, Y) in synchronization with the rotation of the photosensitive member 41 (K, C, M, Y). Toner used as a developer is applied to the electrostatic latent image formed by the optical printing head 101 (K, C, M, Y) used and the optical printing head 101 (K, C, M, Y). The developing device 44 (K, C, M, Y) that makes a visible image (toner image) and the developing device 44 (K, C, M, Y) A primary transfer roller 45 (K, C, M, Y) as transfer means for sequentially transferring the imaged toner image to the intermediate transfer belt 50 as a primary transfer target, and a photoreceptor 41 (K, C, And a cleaning device 46 (K, C, M, Y) as a cleaning means for removing the toner remaining on the surface of M, Y).

  Here, each optical printing head 101 (K, C, M, Y) is separated from the surface of the corresponding photosensitive member 41 (K, C, M, Y) by the working distance WD, and each optical printing head 101 is moved. The (K, C, M, Y) array direction is set along the bus of the photosensitive drum 41 (K, C, M, Y). The emission energy peak wavelength of each optical printing head 101 (K, C, M, Y) and the sensitivity peak wavelength of the photoconductor 41 (K, C, M, Y) are set to substantially coincide with each other. .

  The developing device 44 (K, C, M, Y) uses, for example, a non-magnetic one-component toner as a developer. The film thickness of the developed developer is regulated by a regulation blade, and the potential of the photoreceptor 41 (K, C, M, Y) is adjusted by bringing the developing roller into contact with or pushing the photoreceptor 41 (K, C, M, Y). The toner image is developed by attaching a developer according to the level.

  The black, cyan, magenta, and yellow toner images formed by the four-color single-color toner image forming station are intermediated by the primary transfer bias applied to the primary transfer roller 45 (K, C, M, Y). The toner image, which is sequentially primary transferred onto the transfer belt 50 and sequentially superposed on the intermediate transfer belt 50 to become a full color, is secondarily transferred to a recording medium P such as paper by a secondary transfer roller 66, and serves as a fixing unit. The toner is fixed on the recording medium P by passing through the fixing roller pair 61, and is discharged onto a paper discharge tray 68 formed in the upper part of the apparatus by a paper discharge roller pair 62.

  In FIG. 15, reference numeral 63 denotes a paper feed cassette in which a large number of recording media P are stacked and held, 64 denotes a pickup roller for feeding the recording media P one by one from the paper feed cassette 63, and 65 denotes a secondary transfer roller. A pair of gate rollers for defining the supply timing of the recording medium P to the secondary transfer portion 66, a secondary transfer roller 66 as a secondary transfer means for forming a secondary transfer portion with the intermediate transfer belt 50, 67 Is a cleaning blade as a cleaning means for removing the toner remaining on the surface of the intermediate transfer belt 50 after the secondary transfer.

  The optical printing head of the present invention and the image forming apparatus using the same have been described based on the embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made.

As is apparent from the above description, according to the optical printing head of the present invention and the image forming apparatus using the same, the light is incident on the hemispherical microlens adjacent to the hemispherical microlens at the corresponding position from the light emitting unit or the shutter unit. The thickness of the transparent body is set so that the reflected light is totally reflected by the hemispherical refracting surface or is not refracted toward the image carrier, or the hemisphere at the corresponding position from the light emitting part or the shutter part. The thickness of the transparent body is set so that at least part of the light incident on the hemispherical microlens adjacent to the cylindrical microlens is totally reflected by the hemispherical refractive surface, or the light emitting part of the light emitting element array At each of the alignment positions corresponding to each of the shutter portions of the optical shutter element array, the transparent body and a low refractive index layer having a refractive index lower than the refractive index of the transparent body are sequentially provided. Since Rorenzu is arranged, it can be reduced crosstalk light, stray light. In addition, when a low refractive index layer is interposed, it is possible to increase the distance between the microlens and the light emitting unit or the shutter unit without causing crosstalk, thereby reducing the microlens magnification. Since the energy density on the image carrier is increased and the diameter of the focused spot can be reduced, sufficient resolution and contrast can be obtained.

1 is a schematic cross-sectional view showing a configuration of an optical printing head according to a first embodiment of the present invention. It is an optical path tracking figure in the specific numerical example of a 1st Example. It is a light quantity distribution figure in the example of a concrete numerical value of the 1st example. It is an optical path tracking figure of the comparative example with respect to a 1st Example. It is typical sectional drawing which shows the structure of the optical printing head of the 2nd Example of this invention. It is an optical path tracking figure in the specific numerical example of a 2nd Example. It is a light quantity distribution figure in the example of a concrete numerical value of the 2nd example. It is an optical path tracking figure of the comparative example with respect to a 2nd Example. It is typical sectional drawing which shows the structure of the optical printing head of the 3rd Example of this invention. It is typical sectional drawing which shows the structure of the optical printing head of another Example of this invention. It is a top view of an example of the organic electroluminescent array which can be used as a light modulation element array in this invention. It is sectional drawing of 1 pixel of the array of FIG. It is a figure which shows the structural example of the head of a piezo jet system in an inkjet system. It is a side view which shows the mode of condensing of the optical printing head of this invention. 1 is a front view showing an overall schematic configuration of an example of a tandem color image forming apparatus in which an optical printing head according to the present invention is arranged.

Explanation of symbols

1. Light modulation element array (light emitting element array, optical shutter element array)
2. Light emitting part (shutter part)
DESCRIPTION OF SYMBOLS 3 ... Transparent body 4 ... Micro lens 5 ... Image carrier 6 ... Air layer 7 ... Ball lens 8 ... Fluorine resin coat layer 9 ... Transparent adhesive 10 ... Micro lens 11 ... Transparent substrate 12 ... Spacer 20 ... Organic EL array 21 ... Glass substrate 22 ... Organic EL light emitting part 23 ... Transparent member 24 ... Transparent adhesive (ultraviolet curing type, thermosetting type)
25 ... Light-shielding 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) ... Photoconductor drum 42 (K, C, M, Y) ... Charging means (corona charging) vessel)
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 discharge roller pair 63 ... paper feed cassette 64 ... pickup roller 65 ... gate roller pair 66 ... secondary transfer roller 67 ... cleaning blade 68 ... paper discharge tray 70 ... ink jet System printing device 71 ... head 72 ... nozzle plate 73 ... vibrating plate 74 ... partitioning member (reservoir plate)
75 ... Ink chamber 76 ... Nozzle hole 78 ... Piezoelectric element 79 ... Electrode 101 (K, C, M, Y) ... Optical printing head S using organic EL array ... Surface P ... Recording medium

Claims (11)

In the optical printing head for forming a predetermined pattern on the image carrier by projecting the modulated light beam from the light emitting part of the light emitting element array or the modulated light beam transmitted through the shutter part of the optical shutter element array onto the image carrier. A hemispherical microlens is arranged through a transparent body having a predetermined thickness at an alignment position corresponding to each light emitting part of the element array or each shutter part of the optical shutter element array, and corresponds to the light emitting part or the shutter part. The thickness of the transparent body so that light incident on the hemispherical microlens adjacent to the hemispherical microlens at the position is totally reflected or refracted by the hemispherical refracting surface and does not go to the image carrier. An optical printing head characterized in that is set. In the optical printing head for forming a predetermined pattern on the image carrier by projecting the modulated light beam from the light emitting part of the light emitting element array or the modulated light beam transmitted through the shutter part of the optical shutter element array onto the image carrier. A hemispherical microlens is arranged through a transparent body having a predetermined thickness at an alignment position corresponding to each light emitting part of the element array or each shutter part of the optical shutter element array, and corresponds to the light emitting part or the shutter part. The thickness of the transparent body is set so that at least part of the light incident on the hemispherical microlens adjacent to the hemispherical microlens at the position is totally reflected by the hemispherical refracting surface. Light printing head. The thickness of the transparent body is set to 50% or less of the arrangement pitch of the light emitting parts of the light emitting element array or the arrangement pitch of the shutter parts of the optical shutter element array. Light printing head. In the optical printing head for forming a predetermined pattern on the image carrier by projecting the modulated light beam from the light emitting part of the light emitting element array or the modulated light beam transmitted through the shutter part of the optical shutter element array onto the image carrier. Microlenses are arranged in order through the transparent body and the low refractive index layer having a refractive index lower than the refractive index of the transparent body at the alignment position corresponding to each light emitting section of the element array or each shutter section of the optical shutter element array. An optical printing head characterized by being made. 5. The optical printing head according to claim 4, wherein the low refractive index layer is an air layer. 5. The optical printing head according to claim 4, wherein the low refractive index layer is made of any one of magnesium fluoride, silica airgel, and fluororesin. The optical printing head according to any one of claims 1 to 6, wherein the microlens is made of glass or plastic. 8. The optical printing head according to claim 1, wherein the microlens is provided with an antireflection coating. 9. The optical printing head according to claim 4, wherein the microlens is a hemispherical lens or a ball lens. 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. The image forming apparatus is provided with at least two image forming stations in which a charging unit, an exposure head, a developing unit, and a transfer unit are arranged around an image carrier, and a transfer medium passes through each station, thereby forming a color image. The image forming apparatus according to claim 10, wherein the image forming apparatus is a tandem type color image forming apparatus.

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